Non Adiabatic Centrifugal Compressor Gas Dynamic Performance Definition
Soldatova, Kristina
2014-01-01
Most centrifugal compressors operate in conditions with negligible heat transfer (adiabatic compression). Their plant tests conditions are similar or close to adiabatic conditions. Test regulations establish measures to diminish influence of a heat transfer “compressor body – atmospheric air” to an exit temperature. Therefore a temperature rise in a compressor is used to calculate a work input coefficient and efficiency. Unlike it high pressure centrifugal compressors of gas turbines and supe...
International Nuclear Information System (INIS)
This report examines the concept and the main characteristics of the torroidal magnet in a tokamak with a strong magnetic field and combined adiabatic compression of the plasma pinch for an experiment to achieve the parameter Q = 1
Study on Efficiency Improvement of Hermetic Rotary Compressors
Matsushima, Masatoshi; Nomura, Tomohiro; Nishimura, Nobuya; Iyota, Hiroyuki; Inaba, Koichi
This research was conducted in order to better identify the torque loss of a hermetic rotary compressor for one revolution, and to directly obtain the actual shaft power of the compressor. A testing compressor and a gas cycle type simplified calorimeter were developed for direct measurement of the compressor torque. A strain gauge was stuck on the shaft between a compressor and a motor. Thus, the compressor torque could be measured directly by the strain gauge and data were transmitted to out of the compressor's vessel through a slip ring. Rotational speed of the compressor was measured by using a gap sensor also. From these measurement results, actual shaft power was calculated experimentally. On the other hand, effective compressive torque for compressing refrigerant gas was predicted theoretically. From both experimental and theoretical results, torque loss of the compressor was determined as the difference of the compressor torque from the effective compressive torque. Consequently, a loss of over-compression could be revealed from the torque loss experimentally. Furthermore, overall adiabatic efficiencies of compressors obtained by the actual shaft power were 1.1∼3.5% higher than former overall adiabatic efficiencies obtained by the motor output.
Axisymmetric Toroidal Equilibrium with Sheared Toroidal Flows
Institute of Scientific and Technical Information of China (English)
石秉仁
2002-01-01
Problem of the axisymmetric toroidal equilibrium with pure sheared toroidal flow is involved. For standard tokamak equilibrium, general approximate solutions are analytically pursued for arbitrary current profile and non-circular cross-section. Equilibrium properties including the flow-induced density asymmetry are analyzed.
Raybould, T. A.; Fedotov, V. A.; Papasimakis, N.; Kuprov, I.; Youngs, I. J.; Chen, W. T.; Tsai, D. P.; Zheludev, N. I.
2016-07-01
We demonstrate that the induced toroidal dipole, represented by currents flowing on the surface of a torus, makes a distinct and indispensable contribution to circular dichroism. We show that toroidal circular dichroism supplements the well-known mechanism involving electric dipole and magnetic dipole transitions. We illustrate this with rigorous analysis of the experimentally measured polarization-sensitive transmission spectra of an artificial metamaterial, constructed from elements of toroidal symmetry. We argue that toroidal circular dichroism will be found in large biomolecules with elements of toroidal symmetry and should be taken into account in the interpretation of circular dichroism spectra of organics.
PECULIARITIES OF THE IDEALIZED CYCLES OF VAPOR COMPRESSOR REFRIGERATING MACHINES
Вассерман, А. А.; Лавренченко, Г. К.; Слынько, А. Г.
2014-01-01
Efficiency of the idealized cycles of vapor compressor refrigerating machines with adiabatic or isothermal compression of refrigerantwas investigated. To these cycles concern cycles with adiabatic compression of steam without regeneration (S-cycle) and with limiting regeneration (SR-cycle), and also with isothermal compression and limiting regeneration (T-cycle). Three characteristics of cycles are compared: refrigerating coefficient of performance e, specific-volume cooling capacity qv and t...
Energy Technology Data Exchange (ETDEWEB)
James E. Fisher; Cliff B. Davis; Walter L. Weaver
2005-06-01
A compressor model has been implemented in the RELAP5-3D© code. The model is similar to that of the existing pump model, and performs the same function on a gas as the pump performs on a single-phase or two-phase fluid. The compressor component consists of an inlet junction and a control volume, and optionally, an outlet junction. This feature permits cascading compressor components in series. The equations describing the physics of the compressor are derived from first principles. These equations are used to obtain the head, the torque, and the energy dissipation. Compressor performance is specified using a map, specific to the design of the machine, in terms of the ratio of outlet-to-inlet total (or stagnation) pressure and adiabatic efficiency as functions of rotational velocity and flow rate. The input quantities are specified in terms of dimensionless variables, which are corrected to stagnation density and stagnation sound speed. A small correction was formulated for the input of efficiency to account for the error introduced by assumption of constant density when integrating the momentum equation. Comparison of the results of steady-state operation of the compressor model to those of the MIT design calculation showed excellent agreement for both pressure ratio and power.
Hedberg V
On the 15th of June 2001 the EB approved a new conceptual design for the toroid shield. In the old design, shown in the left part of the figure above, the moderator part of the shielding (JTV) was situated both in the warm and cold areas of the forward toroid. It consisted both of rings of polyethylene and hundreds of blocks of polyethylene (or an epoxy resin) inside the toroid vacuum vessel. In the new design, shown to the right in the figure above, only the rings remain inside the toroid. To compensate for the loss of moderator in the toroid, the copper plug (JTT) has been reduced in radius so that a layer of borated polyethylene can be placed around it (see figure below). The new design gives significant cost-savings and is easier to produce in the tight time schedule of the forward toroid. Since the amount of copper is reduced the weight that has to be carried by the toroid is also reduced. Outgassing into the toroid vacuum was a potential problem in the old design and this is now avoided. The main ...
2002-01-01
Because of its exceptional size, it was not feasible to assemble and test the Barrel Toroid - made of eight coils - as an integrated toroid on the surface, prior to its final installation underground in LHC interaction point 1. It was therefore decided to test these eight coils individually in a dedicated test facility.
Induced toroid structures and toroid polarizabilities
International Nuclear Information System (INIS)
The frequency-dependent toroid dipole polarizability γ(ω) of a (nonrelativistic, spinless) hydrogen-like atom in its ground state is calculated analytically in terms of two Gauss hypergeometric functions. The static result reads simply γ(ω=0)=(23/60)α2Z-4a05 (α - fine structure constant, Z - nucleus charge number, a0 - Bohr radius). Comparing the present evaluations for H-like atoms with previous ones for pions, one sees that the role of the induced toroid moments (as against that of the usual electric ones) increases considerably when passing from atomic to particle physics
Core compressor exit stage study. 1: Aerodynamic and mechanical design
Burdsall, E. A.; Canal, E., Jr.; Lyons, K. A.
1979-01-01
The effect of aspect ratio on the performance of core compressor exit stages was demonstrated using two three stage, highly loaded, core compressors. Aspect ratio was identified as having a strong influence on compressors endwall loss. Both compressors simulated the last three stages of an advanced eight stage core compressor and were designed with the same 0.915 hub/tip ratio, 4.30 kg/sec (9.47 1bm/sec) inlet corrected flow, and 167 m/sec (547 ft/sec) corrected mean wheel speed. The first compressor had an aspect ratio of 0.81 and an overall pressure ratio of 1.357 at a design adiabatic efficiency of 88.3% with an average diffusion factor or 0.529. The aspect ratio of the second compressor was 1.22 with an overall pressure ratio of 1.324 at a design adiabatic efficiency of 88.7% with an average diffusion factor of 0.491.
Energy Technology Data Exchange (ETDEWEB)
Roberts, II, William Byron; Lawlor, Shawn P.; Breidenthal, Robert E.
2016-04-12
A supersonic compressor including a rotor to deliver a gas at supersonic conditions to a diffuser. The diffuser includes a plurality of aerodynamic ducts that have converging and diverging portions, for deceleration of gas to subsonic conditions and then for expansion of subsonic gas, to change kinetic energy of the gas to static pressure. The aerodynamic ducts include vortex generating structures for controlling boundary layer, and structures for changing the effective contraction ratio to enable starting even when the aerodynamic ducts are designed for high pressure ratios, and structures for boundary layer control. In an embodiment, aerodynamic ducts are provided having an aspect ratio of in excess of two to one, when viewed in cross-section orthogonal to flow direction at an entrance to the aerodynamic duct.
Axisymmetric Toroidal Equilibrium with Sheared Toroidal Flows
Institute of Scientific and Technical Information of China (English)
SHIBingren
2002-01-01
Since the early 1960' s, the developments of the tokamak research make plasma flows a reality in many devices where neutral beam injections were used as heating in general and refueling in particular. Compared to the static axi-symmetric toroidal equilibrium that
Similarity and cascade flow characteristics of a highly loaded helium compressor
International Nuclear Information System (INIS)
Highlights: • The deviation of different similarity criteria is analyzed theoretically. • Flow difference between helium and air compressor cascades is analyzed numerically. • The analysis of calculated results validates the theoretical derivation. • Flow characteristics of highly loaded helium compressor blade profile are computed. - Abstract: Helium compressor is a major component of the Power Conversion Unit (PCU) used in a High Temperature Gas Cooled Reactor (HTGR). Because the high cost of closed cycle test and leakage problem of helium gas, air could be used as working fluid instead of helium in compressor performance tests. However, the properties of Helium are largely different from those of air, e.g. the adiabatic exponent of Helium is 1.6, while the adiabatic exponent itself is a criterion of similarity between the two compressors. The characteristics of compressor will be different due to the effect of the adiabatic exponent of working fluid, especially for highly loaded compressor working at higher inlet Mach number. In this paper, a theoretical study on the similarity between air compressor and a highly loaded helium compressor is carried out and the deviation of similarity is analyzed. Numerical simulations are then used to confirm the theoretical analysis. The results indicate that the similarity deviation could not be neglected for highly loaded compressor cascade, which means the experience and experimental results of those conventional air compressor cannot be applied directly to the design of highly loaded helium compressor. The flow characteristics of a highly loaded helium compressor at different Reynolds numbers, attack angles, Mach numbers and cascade geometries are then investigated
Similarity and cascade flow characteristics of a highly loaded helium compressor
Energy Technology Data Exchange (ETDEWEB)
Jiang, Bin, E-mail: jiangbin_hrbeu@163.com [College of Power & Energy Engineering of Harbin Engineering University, Harbin 150001 (China); Chen, Zhongliang [College of Power & Energy Engineering of Harbin Engineering University, Harbin 150001 (China); Chen, Hang [AVIG Shenyang Engine Design and Research Institute, Shenyang 110015 (China); Zhang, Hai; Zheng, Qun [College of Power & Energy Engineering of Harbin Engineering University, Harbin 150001 (China)
2015-05-15
Highlights: • The deviation of different similarity criteria is analyzed theoretically. • Flow difference between helium and air compressor cascades is analyzed numerically. • The analysis of calculated results validates the theoretical derivation. • Flow characteristics of highly loaded helium compressor blade profile are computed. - Abstract: Helium compressor is a major component of the Power Conversion Unit (PCU) used in a High Temperature Gas Cooled Reactor (HTGR). Because the high cost of closed cycle test and leakage problem of helium gas, air could be used as working fluid instead of helium in compressor performance tests. However, the properties of Helium are largely different from those of air, e.g. the adiabatic exponent of Helium is 1.6, while the adiabatic exponent itself is a criterion of similarity between the two compressors. The characteristics of compressor will be different due to the effect of the adiabatic exponent of working fluid, especially for highly loaded compressor working at higher inlet Mach number. In this paper, a theoretical study on the similarity between air compressor and a highly loaded helium compressor is carried out and the deviation of similarity is analyzed. Numerical simulations are then used to confirm the theoretical analysis. The results indicate that the similarity deviation could not be neglected for highly loaded compressor cascade, which means the experience and experimental results of those conventional air compressor cannot be applied directly to the design of highly loaded helium compressor. The flow characteristics of a highly loaded helium compressor at different Reynolds numbers, attack angles, Mach numbers and cascade geometries are then investigated.
Invisibility cloaks for toroids.
You, Yu; Kattawar, George W; Yang, Ping
2009-04-13
The material properties of toroidal invisibility cloaks are derived based on the coordinate transformation method. The permittivity and permeability tensors for toroidal cloaks are substantially different from those for spherical cloaks, but quite similar to those for 2D cylindrical cloaks because a singularity is involved at the inner boundary in both the cases. The cloaking effect is confirmed by the electric field distribution in the vicinity of toroidal cloaks simulated from the generalized discrete-dipole approximation (DDA) method. This study extends the concept of electromagnetic cloaking of arbitrarily-shaped objects to a complex geometry. PMID:19365485
Centrifugal reciprocating compressor
High, W. H.
1980-01-01
Efficient compressor uses centrifugal force to compress gas. System incorporates two coupled dc motors, each driving separate centrifugal reciprocating-compressor assembly. Motors are synchronized to accelerate and decelerate alternately.
Adiabatic turbocompound diesel engine
Energy Technology Data Exchange (ETDEWEB)
Kamo, R.; Bryzik, W.
1984-02-01
The research and development of an adiabatic turbocompound engine have shown that the concept is feasible. The ability to meet the performance and sociability goals of the future power plants has been demonstrated. Low brake specific fuel consumption, low smoke and particulates, better NO /SUB x/ -BSFC trade-off, excellent multifuel capability, white smoke suppression, and potentially lower maintenance and greater reliability and durability are some of the attributes. The absence of the water cooling system adds to its attractiveness because of lower installed weight, cost, and reduction in parasitic losses. The operating environment of an adiabatic engine is shown as the basis for analysis and designing of adiabatic components. The types of material which can satisfy the needs of an adiabatic engine are presented. These materials include high temperature metals, high performance ceramics, and glass ceramics. The use of a turbocompound system to utilize the increased exhaust energy of an adiabatic engine is covered. A minimum fuel consumption of 0.285 lb/bhp-hr was achieved at 200 psi BMEP. Although the technical feasibility and viability of an adiabatic engine was demonstrated, the adiabatic diesel engine has problems which must be solved before it becomes a commercially viable product. These problem areas where more work is required are discussed.
Quantum adiabatic machine learning
Pudenz, Kristen L
2011-01-01
We develop an approach to machine learning and anomaly detection via quantum adiabatic evolution. In the training phase we identify an optimal set of weak classifiers, to form a single strong classifier. In the testing phase we adiabatically evolve one or more strong classifiers on a superposition of inputs in order to find certain anomalous elements in the classification space. Both the training and testing phases are executed via quantum adiabatic evolution. We apply and illustrate this approach in detail to the problem of software verification and validation.
Impact of Turbocharger Non-Adiabatic Operation on Engine Volumetric Efficiency and Turbo Lag
Directory of Open Access Journals (Sweden)
S. Shaaban
2012-01-01
Full Text Available Turbocharger performance significantly affects the thermodynamic properties of the working fluid at engine boundaries and hence engine performance. Heat transfer takes place under all circumstances during turbocharger operation. This heat transfer affects the power produced by the turbine, the power consumed by the compressor, and the engine volumetric efficiency. Therefore, non-adiabatic turbocharger performance can restrict the engine charging process and hence engine performance. The present research work investigates the effect of turbocharger non-adiabatic performance on the engine charging process and turbo lag. Two passenger car turbochargers are experimentally and theoretically investigated. The effect of turbine casing insulation is also explored. The present investigation shows that thermal energy is transferred to the compressor under all circumstances. At high rotational speeds, thermal energy is first transferred to the compressor and latter from the compressor to the ambient. Therefore, the compressor appears to be “adiabatic” at high rotational speeds despite the complex heat transfer processes inside the compressor. A tangible effect of turbocharger non-adiabatic performance on the charging process is identified at turbocharger part load operation. The turbine power is the most affected operating parameter, followed by the engine volumetric efficiency. Insulating the turbine is recommended for reducing the turbine size and the turbo lag.
Drift in toroidal configurations
Evangelidis, E. A.
1990-12-01
This paper considers possible mechanisms involved in amplifying the drift velocity of plasma particles, under conditions of toroidal geometry. It is shown that particles constrained to move on an axisymmetric circular spheroidal surface, develop a sinusoidal motion with a characteristic frequency which depends on the energy of the particles, the value of the isoflux surface, and the value of the general momentum. It is also shown that the incorporation of the effects of toroidal geometry in the Lorentz equation produces a nonambipolar charge-dependent particle flux amplified by a factor 2(q/epsilon) squared.
Oreshkov, Ognyan
2010-01-01
We propose a theory of adiabaticity in quantum Markovian dynamics based on a structural decomposition of the Hilbert space induced by the asymptotic behavior of the Lindblad semigroup. A central idea of our approach is that the natural generalization of the concept of eigenspace of the Hamiltonian in the case of Markovian dynamics is a noiseless subsystem with a minimal noisy cofactor. Unlike previous attempts to define adiabaticity for open systems, our approach deals exclusively with physical entities and provides a simple, intuitive picture at the underlying Hilbert-space level, linking the notion of adiabaticity to the theory of noiseless subsystems. As an application of our theory, we propose a framework for decoherence-assisted computation in noiseless codes under general Markovian noise. We also formulate a dissipation-driven approach to holonomic computation based on adiabatic dragging of subsystems that is generally not achievable by non-dissipative means.
Compressors selection and sizing
Brown, Royce N
2005-01-01
This practical reference provides in-depth information required to understand and properly estimate compressor capabilities and to select the proper designs. Engineers and students will gain a thorough understanding of compression principles, equipment, applications, selection, sizing, installation, and maintenance. The many examples clearly illustrate key aspects to help readers understand the ""real world"" of compressor technology.Compressors: Selection and Sizing, third edition is completely updated with new API standards. Additions requested by readers include a new section on di
Gravity Independent Compressor Project
National Aeronautics and Space Administration — We propose to develop and demonstrate a small, gravity independent, vapor compression refrigeration system using a linear motor compressor which effectively...
Barstad, Bjørn Ove
2010-01-01
The compressor recycle system is the main focus of this thesis. When the mass flow through a compressor becomes too low, the compressor can plunge into surge. Surge is a term that is used for axisymmetric oscillation through a compressor and is highly unwanted. The recycle system feeds compressed gas back to the intake when the mass flow becomes too low, and thereby act as a safety system.A mathematical model of the recycle system is extended and simulated in SIMULINK. The mathematical model ...
Elongated toroid fusion device
International Nuclear Information System (INIS)
A device for achieving ignition of a plasma with ohmic heating is described comprising: means for defining a toroidal plasma chamber,a and confining gas therein, and means including electrically conductive coils for generating plasma within the chamber and for confining and shaping such plasma substantially into and filling a predetermined single region of the chamber without an axisymmetric internal separatix and ohmically heating the confined plasma to ignition. The predetermined region is toroidal with a major axis defining an axial direction parallel thereto and a transaxial direction perpendicular to the axis and having an axial cross section with an elongation, k, greater than 4, where k is the ratio of the maximum axial dimension of the cross section to the maximum transaxial dimension of the cross section
Adiabatic Liquid Piston Compressed Air Energy Storage
DEFF Research Database (Denmark)
Petersen, Tage; Elmegaard, Brian; Pedersen, Allan Schrøder
This project investigates the potential of a Compressed Air Energy Storage system (CAES system). CAES systems are used to store mechanical energy in the form of compressed air. The systems use electricity to drive the compressor at times of low electricity demand with the purpose of converting...... the mechanical energy into electricity at times of high electricity demand. Two such systems are currently in operation; one in Germany (Huntorf) and one in the USA (Macintosh, Alabama). In both cases, an underground cavern is used as a pressure vessel for the storage of the compressed air. Both systems...... a turbine when discharging. In this case, the liquid works effectively as a piston compressing the gas in the vessel, hence the name “Adiabatic Liquid Piston Compressed Air Energy Storage” (ALP-CAES). The compression ratio of the gas in the vessel (ratio between maximum and minimum pressure) is relatively...
Bidirectional grating compressors
Wang, Cheng; Li, Zhaoyang; Li, Shuai; Liu, Yanqi; Leng, Yuxin; Li, Ruxin
2016-07-01
A bidirectional grating compressor for chirped pulse amplifiers is presented. It compresses a laser beam simultaneously in two opposite directions. The pulse compressor is shown to promote chirped pulse amplifiers' output energy without grating damages. To verify the practicability, an experiment is carried out. In addition, a crosscorrelation instrument is designed and set up to test the time synchronization between these two femtosecond pulses.
Operating experiences and test results of six cold helium compressors
Brown, D. P.; Gibbs, R. J.; Schlafke, A. P.; Sondericker, J. H.; Wu, K. C.
Three small and three large cold helium centrifugal compressors have been operated at Brookhaven National Laboratory between 1981 and 1986. The three small cold compressors have been installed on a 1000 W refrigerator for testing a string of superconducting magnets and for R and D purposes. The three large units are components of the BNL 24.8 KW refrigerator to be used to provide cooling for the RHIC project. These compressors are used either to circulate a large amount of supercritical helium through a group of magnets or to pump on the helium bath to reduce temperature in the system. One small circulating compressor tested employs tilting-pad gas bearings and is driven by a DC motor. The two small cold vacuum pumps tested use oil bearings and are driven by oil turbines. The three large oil-bearing cold compressors are driven by DC motors through a gear box. A unique feature of the large vacuum pump is the combination of two pumps with a total of four stages on the same shaft. The adiabatic efficiencies are found to be 57% for the large vacuum pumps and close to 50% for the large circulating compressor. Good overall reliability has been experienced.
Study of blade aspect ratio on a compressor front stage aerodynamic and mechanical design report
Burger, G. D.; Lee, D.; Snow, D. W.
1979-01-01
A single stage compressor was designed with the intent of demonstrating that, for a tip speed and hub-tip ratio typical of an advanced core compressor front stage, the use of low aspect ratio can permit high levels of blade loading to be achieved at an acceptable level of efficiency. The design pressure ratio is 1.8 at an adiabatic efficiency of 88.5 percent. Both rotor and stator have multiple-circular-arc airfoil sections. Variable IGV and stator vanes permit low speed matching adjustments. The design incorporates an inlet duct representative of an engine transition duct between fan and high pressure compressor.
Thermodynamic Analysis of the Diabatic Efficiency of Turbines and Compressors
Energy Technology Data Exchange (ETDEWEB)
Park, Kyoung Kuhn [Kookmin Univ., Seoul (Korea, Republic of)
2016-03-15
Thermodynamic analysis is conducted on the first-order approximation model for turbines and compressors. It is shown that the adiabatic efficiency could be greater than unity, depending on the entropic mean temperature, entropy generation, thermal reservoir temperature, and heat transfer. Therefore, adiabatic efficiency applied to a diabatic control volume results in an error overestimating its performance. To resolve this overestimation, it is suggested that a reversible diabatic process be referred to as an ideal process to evaluate diabatic efficiency . The diabatic efficiency suggested in this work is proven to always be less than unity and it is smaller than the exergy efficiency in most cases. The diabatic efficiency could be used as a more general definition of efficiency, which would include adiabatic efficiency.
A Rotating Bose-Einstein Condensation in a Toroidal Trap
Institute of Scientific and Technical Information of China (English)
文渝川; 张鹏鸣; 李师杰
2011-01-01
We have studied the ground state configurations of a rotating Bose-Einstein condensation in a toroidal trap as the radius of the central Ganssian potentiaJ expands adiabatically. Firstly, we observe that the vortices are devoured successively into the central hole of the condensate to form a giant vortex as the radius of the trap expands. When all the pre-existing vortices are absorbed, the angular momentum of the system still increase as the radius of the ganssian potential enlarges. When increasing the interaction strength, we find that more singly quantized vortices are squeezed into the condensate, but the giant vortex does not change.
On the Toroidal Leibniz Algebras
Institute of Scientific and Technical Information of China (English)
Dong LIU; Lei LIN
2008-01-01
Toroidal Leibniz algebras are the universal central extensions of the iterated loop algebras gOC[t±11 ,...,t±v1] in the category of Leibniz algebras. In this paper, some properties and representations of toroidal Leibniz algebras are studied. Some general theories of central extensions of Leibniz algebras are also obtained.
Cooled spool piston compressor
Morris, Brian G. (Inventor)
1993-01-01
A hydraulically powered gas compressor receives low pressure gas and outputs a high pressure gas. The housing of the compressor defines a cylinder with a center chamber having a cross-sectional area less than the cross-sectional area of a left end chamber and a right end chamber, and a spool-type piston assembly is movable within the cylinder and includes a left end closure, a right end closure, and a center body that are in sealing engagement with the respective cylinder walls as the piston reciprocates. First and second annual compression chambers are provided between the piston enclosures and center housing portion of the compressor, thereby minimizing the spacing between the core gas and a cooled surface of the compressor. Restricted flow passageways are provided in the piston closure members and a path is provided in the central body of the piston assembly, such that hydraulic fluid flows through the piston assembly to cool the piston assembly during its operation. The compressor of the present invention may be easily adapted for a particular application, and is capable of generating high gas pressures while maintaining both the compressed gas and the compressor components within acceptable temperature limits.
Nonresonance adiabatic photon trap
Popov, S S; Burdakov, A V; Ushkova, M Yu
2016-01-01
Concept of high efficiency photon storage based on adiabatic confinement between concave mirrors is presented and experimentally investigated. The approach is insensitive to typical for Fabri-Perot cells requirements on quality of accumulated radiation, tolerance of resonator elements and their stability. Experiments have been carried out with the trap, which consists from opposed concave cylindrical mirrors and conjugated with them spherical mirrors. In result, high efficiency for accumulation of radiation with large angular spread and spectrum width has been confirmed. As radiation source a commercial fiber laser has been used.
Compressor map prediction tool
Ravi, Arjun; Sznajder, Lukasz; Bennett, Ian
2015-08-01
Shell Global Solutions uses an in-house developed system for remote condition monitoring of centrifugal compressors. It requires field process data collected during operation to calculate and assess the machine's performance. Performance is assessed by comparing live results of polytropic head and efficiency versus design compressor curves provided by the Manufacturer. Typically, these design curves are given for specific suction conditions. The further these conditions on site deviate from those prescribed at design, the less accurate the health assessment of the compressor becomes. To address this specified problem, a compressor map prediction tool is proposed. The original performance curves of polytropic head against volumetric flow for varying rotational speeds are used as an input to define a range of Mach numbers within which the non-dimensional invariant performance curve of head and volume flow coefficient is generated. The new performance curves of polytropic head vs. flow for desired set of inlet conditions are then back calculated using the invariant non-dimensional curve. Within the range of Mach numbers calculated from design data, the proposed methodology can predict polytropic head curves at a new set of inlet conditions within an estimated 3% accuracy. The presented methodology does not require knowledge of detailed impeller geometry such as throat areas, blade number, blade angles, thicknesses nor other aspects of the aerodynamic design - diffusion levels, flow angles, etc. The only required mechanical design feature is the first impeller tip diameter. Described method makes centrifugal compressor surveillance activities more accurate, enabling precise problem isolation affecting machine's performance.
Directory of Open Access Journals (Sweden)
J. D. Biamonte
2011-06-01
Full Text Available In his famous 1981 talk, Feynman proposed that unlike classical computers, which would presumably experience an exponential slowdown when simulating quantum phenomena, a universal quantum simulator would not. An ideal quantum simulator would be controllable, and built using existing technology. In some cases, moving away from gate-model-based implementations of quantum computing may offer a more feasible solution for particular experimental implementations. Here we consider an adiabatic quantum simulator which simulates the ground state properties of sparse Hamiltonians consisting of one- and two-local interaction terms, using sparse Hamiltonians with at most three-local interactions. Properties of such Hamiltonians can be well approximated with Hamiltonians containing only two-local terms. The register holding the simulated ground state is brought adiabatically into interaction with a probe qubit, followed by a single diabatic gate operation on the probe which then undergoes free evolution until measured. This allows one to recover e.g. the ground state energy of the Hamiltonian being simulated. Given a ground state, this scheme can be used to verify the QMA-complete problem LOCAL HAMILTONIAN, and is therefore likely more powerful than classical computing.
Equivalent Linkages of Compressor Mechanisms
Bukac, Hubert
2014-01-01
Frequently, the dynamics of a compressor’s mechanism can be simplified and better understood by analyzing compressor’s equivalent linkage. Although the equivalent linkage of a reciprocating piston compressor is well known, the equivalent linkages of other types of compressors are not. For example, it is not well understood that the equivalent linkage of a rolling piston compressor is also the same slider-crank mechanism as the one of a reciprocating piston compressor. The difference between r...
Electrochemical Hydrogen Compressor
Energy Technology Data Exchange (ETDEWEB)
Lipp, Ludwig [FuelCell Energy, Inc., Torrington, CT (United States)
2016-01-21
Conventional compressors have not been able to meet DOE targets for hydrogen refueling stations. They suffer from high capital cost, poor reliability and pose a risk of fuel contamination from lubricant oils. This project has significantly advanced the development of solid state hydrogen compressor technology for multiple applications. The project has achieved all of its major objectives. It has demonstrated capability of Electrochemical Hydrogen Compression (EHC) technology to potentially meet the DOE targets for small compressors for refueling sites. It has quantified EHC cell performance and durability, including single stage hydrogen compression from near-atmospheric pressure to 12,800 psi and operation of EHC for more than 22,000 hours. Capital cost of EHC was reduced by 60%, enabling a path to meeting the DOE cost targets for hydrogen compression, storage and delivery ($2.00-2.15/gge by 2020).
Toroidal Multipole Confinement Experiment
International Nuclear Information System (INIS)
Confinement of plasma is studied in the General Atomic toroidal octopole machine. The magnetic field is produced by four current carrying rings supported inside a contoured conductor. The rings are energized by a transformer core linking the machine. The major radius of the machine is 63.5 cm with an aspect ratio of 5. The magnetic field on the minor axis is zero and increases to 3500 G at the wall between the rings. After crowbarring, the field decays in 6 msec to its half value. The MHD stability calculation has been carried out and the stability is assured up to the plasma pressure of 1016 eV cm-3. Hydrogen plasmas from either a coaxial gun or a pinch gun with ion energies of 50 to 200 eV and with densities of 1014 cm-3 are successfully injected through a port located at the outer conductor wall. After the injection, plasma spreads azimuthally, filling the machine. Electric probes, magnetic probes, and calorimetric probes have been used extensively. Optical spectrometers and particle detectors are also used. The initial plasma density of 1013 cm-'3 decays with a time constant of 700 μsec. The electron temperature decays more quickly in about 100 μsec. No electric or magnetic fluctuations have been observed on any of the probes. Since no provision is made to avoid the plasma loss to the ring supports which penetrate the plasma region, the decay of ion temperature may be attributed to the support loss. (author)
Hyperbolically Shaped Centrifugal Compressor
Institute of Scientific and Technical Information of China (English)
Romuald Puzyrewski; Pawel Flaszy(n)ski
2003-01-01
Starting from the classical centrifugal compressor, cone shaped in meridional cross section, two modifications are considered on the basis of results from 2D and 3D flow models. The first modification is the change of the meridional cross section to hyperbolically shaped channel. The second modification, proposed on the basis of 2D axisymmetric solution, concerns the shape of blading. On the strength of this solution the blades are formed as 3D shaped blades, coinciding with the recent tendency in 3D designs. Two aims were considered for the change of meridional compressor shape. The first was to remove the separation zone which appears as the flow tums from axial to radial direction. The second aim is to uniformize the flow at exit of impeller. These two goals were considered within the frame of 2D axisymmetric model. Replacing the cone shaped compressor by a hyperbolically shaped one, the separation at the corner was removed. The disc and shroud shape of the compressor was chosen in the way which satisfies the condition of most uniform flow at the compressor exit. The uniformity of exit flow from the rotor can be considered as the factor which influences the performance of the diffuser following the rotor. In the 2D model a family of stream surfaces of S1 type is given in order to find S2 surfaces which may be identified with the midblade surfaces of compressor blading. A computation of 3D type has been performed in order to establish the relations between 2D and 3D models in the calculation of flow parameters. In the presented example the 2D model appears as the inverse model which leads to 3D shape of blading whereas the 3D model has been used for the direct solution. In the presented example the confrontation of two models, 2D and 3D, leads to a better understanding of the application of these models to the design procedure.
Energy Technology Data Exchange (ETDEWEB)
Galkowski, A. [Institute of Atomic Energy, Otwock-Swierk (Poland)
1994-12-31
Non-linear ideal MHD equilibria in axisymmetric system with flows are examined, both in 1st and 2nd ellipticity regions. Evidence of the bifurcation of solutions is provided and numerical solutions of several problems in a tokamak geometry are given, exhibiting bifurcation phenomena. Relaxation of plasma in the presence of zero-order flows is studied in a realistic toroidal geometry. The field aligned flow allows equilibria with finite pressure gradient but with homogeneous temperature distribution. Numerical calculations have been performed for the 1st and 2nd ellipticity regimes of the extended Grad-Shafranov-Schlueter equation. Numerical technique, alternative to the well-known Grad`s ADM methods has been proposed to deal with slow adiabatic evolution of toroidal plasma with flows. The equilibrium problem with prescribed adiabatic constraints may be solved by simultaneous calculations of flux surface geometry and original profile functions. (author). 178 refs, 37 figs, 5 tabs.
Geometry of the Adiabatic Theorem
Lobo, Augusto Cesar; Ribeiro, Rafael Antunes; Ribeiro, Clyffe de Assis; Dieguez, Pedro Ruas
2012-01-01
We present a simple and pedagogical derivation of the quantum adiabatic theorem for two-level systems (a single qubit) based on geometrical structures of quantum mechanics developed by Anandan and Aharonov, among others. We have chosen to use only the minimum geometric structure needed for the understanding of the adiabatic theorem for this case.…
Eijk, A.; Lier, L.J. van
2010-01-01
The increasing demand for economic plant operation has led to a critical discussion of the equipment as to selection, design, maintenance and automation. The well-known advantages of the reciprocating compressor such as high efficiency under many different operating conditions, comparatively easy re
Compressor health monitoring toolkit
Energy Technology Data Exchange (ETDEWEB)
Harrell, John Jr.; Harris, Ralph E.; Smalley, Anthony J. [Southwest Research Institute (United States)
2002-04-01
Techniques for monitoring large engines and compressors are described under the following headings: lube oil analysis with particle counting; bearing temperature prediction; crankshaft web deflection measurement; crankshaft bending stress prediction; direct crankshaft strain measurement; shaft torque measurements; and operational deflection shape. (UK)
Impact of Turbocharger Non-Adiabatic Operation on Engine Volumetric Efficiency and Turbo Lag
Shaaban, S; Seume, J.
2012-01-01
Turbocharger performance significantly affects the thermodynamic properties of the working fluid at engine boundaries and hence engine performance. Heat transfer takes place under all circumstances during turbocharger operation. This heat transfer affects the power produced by the turbine, the power consumed by the compressor, and the engine volumetric efficiency. Therefore, non-adiabatic turbocharger performance can restrict the engine charging process and hence engine performance. The prese...
Heavy ion toroidal collective accelerator
International Nuclear Information System (INIS)
Experiments on HIPAC at Maxwell Laboratories have shown that almost all of the confined electrons are trapped and do not go around the torus. A toroidal electric field produces a negligible toroidal electron current. An ion accelerator where electrons are magnetically contained and their space charge contains ions is considered. A toroidal electric field of suitable magnitude can be applied so that it accelerates all of the ions but does not accelerate most of the electrons. This is possible if the magnetic moment of electrons μsub(e) > μsub(i)/Z, where μsub(i) is the ion magnetic moment and Z is the charge of the ion. Ions would be contained by the electron space-charge electric field E, for energies up to ZeER/2 approximately 100 GeV where Z = 60, E = 107 V/cm and the major radius of the torus is R = 3.3 metres. (author)
RF breakdown by toroidal helicons
Indian Academy of Sciences (India)
S K P Tripathi; D Bora; M Mishra
2001-04-01
Bounded whistlers are well-known for their efﬁcient plasma production capabilities in thin cylindrical tubes. In this paper we shall present their radio frequency (RF) breakdown and discharge sustaining capabilities in toroidal systems. Pulsed RF power in the electronmagnetohydrodynamic (EMHD) frequency regime is fed to the neutral background medium. After the breakdown stage, discharge is sustained by toroidal bounded whistlers. In these pulsed experiments the behaviour of the time evolution of the discharge could be studied in four distinct phases of RF breakdown, steady state attainment, decay and afterglow. In the steady state average electron density of ≈ 1012 per cc and average electron temperature of ≈ 20 eV are obtained at 10-3 mbar of argon ﬁlling pressure. Experimental results on toroidal mode structure, background effects and time evolution of the electron distribution function will be presented and their implications in understanding the breakdown mechanism are discussed.
Numerical design optimization of compressor blade based on ADOP
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
An aerodynamic design optimization platform (ADOP) has been developed. The numerical optimization method is based on genetic algorithm (GA), Pareto ranking and fitness sharing technique. The platform was used for design optimization of the stator of an advanced transonic stage to seek high adiabatic efficiency. The compressor stage efficiency is increased by 0.502% at optimal point and the stall margin is enlarged by nearly 1.0% at design rotating speed. The flow fields of the transonic stage were simulated with FINE/Turbo software package. The optimization result indicates that the optimization platform is effective in 3D numerical design optimization problems.
Hybrid winding concept for toroids
DEFF Research Database (Denmark)
Schneider, Henrik; Andersen, Thomas; Knott, Arnold;
2013-01-01
This paper proposes a hybrid winding concept for toroids using the traces in a printed circuit board to make connection to bended copper foil cutouts. In a final product a number of strips with a certain thickness would be held by a former and the whole assembly could be placed by pick...... and placement machinery. This opens up the possibility for both an automated manufacturing process and an automated production process of toroidal magnetics such as power inductors, filtering inductors, air core inductors, transformers etc. Both the proposed hybrid and the common wire wound winding...
The complex and unique ATLAS Toroid family
2002-01-01
Big parts for the toroid magnets that will be used in the ATLAS experiment have been continuously arriving at CERN since March. These structures will create the largest superconducting toroid magnet ever.
Performance in Centrifugal Compressors
Directory of Open Access Journals (Sweden)
K. Sato
1999-01-01
Full Text Available A 3-D unsteady thin-layer Navier-Stokes code has been used to calculate the flow through a centrifugal compressor stage. The validation of the code for steady flows in centrifugal compressors was conducted for the Krain’s impeller with a vaneless diffuser as a test case and the numerical results were compared with the experimental results. The predicted flow field and performance agreed well with the experimental data. An unsteady stage solution was then conducted with this impeller followed by a generic low-solidity vaned-diffuser to examine the unsteady effects on the impeller performance. The computational results showed a stabilising effect of the blade row interaction.
Performance analysis of adiabatic engine
Energy Technology Data Exchange (ETDEWEB)
Sudhakar, V.
1984-01-01
As the development of the adiabatic diesel engine continues with a goal of 65% reduction in net in-cylinder heat transfer over a cooled engine, several uncooled engines with intermediate levels of reduced heat transfer were studied. Some aspects and results of the adiabatic diesel engine cycle simulation are discussed. Performance test data and simulation results are compared for a conventionally cooled and uncooled Cummins NH-450 turbocompound engines. Exhaust emissions were also measured and compared.
Intrinsic rotation of toroidally confined magnetohydrodynamics
Morales, Jorge; Bos, Wouter; Schneider, Kai; Montgomery, David
2012-01-01
The spatiotemporal self-organization of viscoresistive magnetohydrodynamics (MHD) in a toroidal geometry is studied. Curl-free toroidal magnetic and electric fields are imposed. It is observed in our simulations that a flow is generated, which evolves from dominantly poloidal to toroidal when the Lundquist numbers are increased. It is shown that this toroidal organization of the flow is consistent with the tendency of the velocity field to align with the magnetic field. Up-down asymmetry of t...
Gas path diagnostics for compressors
Salamat, Reza
2012-01-01
The use and application of compressors cannot be overemphasized in the aeronautical and oil & gas industries. Yet research works in sufficient depth has not been conducted previously to analyze their actual behaviour under degraded or even new conditions in operation. For the purpose of degradation modeling and simulation, a compressor model was set up using thermodynamic equations and affinity laws representing the characteristics of a clean compressor. HYSYS was used for degradation mode...
ATLAS End Cap toroid in upstanding position
2005-01-01
End Cap toroid The ATLAS End Cap toroid weights 240-ton and is 12-m diameter high. The parts of this vacuum vessel had to be integrated and tested so that End Cap Toroid has no leaks. After that it could be cooled down to 80 K.
Extremely high Q-factor toroidal metamaterials
Basharin, Alexey A; Volsky, Nikita; Kafesaki, Maria; Economou, Eleftherios N; Ustinov, Alexey V
2016-01-01
We demonstrate that, owing to the unique topology of the toroidal dipolar mode, its electric/magnetic field can be spatially confined within subwavelength, externally accessible regions of the metamolecules, which makes the toroidal planar metamaterials a viable platform for high Q-factor resonators due to interfering toroidal and other dipolar modes in metamolecules.
Technology of toroidal plasma devices
International Nuclear Information System (INIS)
After research into many different magnetic confinement systems, there is now general agreement that the most favorable ones for future fusion reactors are all based on toroidal geometry, as distinct from having open ends like mirror machines. For this reason plasma physics research, even when not aimed directly at the fusion problems, has in recent years increasingly concentrated on toroidal systems. One reason is that by using their good confinement properties the experimenter has available a range of high temperature plasma parameters in quasisteady (or even steady) state conditions not otherwise available on Earth. Despite the wide variety of both geometrical possibilities and sizes, ranging from table-top experiments with plasmas a few centimetres across to near reactor scale ones like JET with plasmas several metres across, toroidal systems have many common features, both in their physical principles and of experimental design: the purpose of this paper is to highlight those common features, using some specific examples for illustration, and emphasizing some of the more practical aspects. It will also try to point out important differences between two of the main classes of toroidal systems
Lowering the first ATLAS toroid
Maximilien Brice
2004-01-01
The ATLAS detector on the LHC at CERN will consist of eight toroid magnets, the first of which was lowered into the cavern in these images on 26 October 2004. The coils are supported on platforms where they will be attached to form a giant torus. The platforms will hold about 300 tonnes of ATLAS' muon chambers and will envelop the inner detectors.
Toroidal solutions in Horava Gravity
Ghodsi, Ahmad
2009-01-01
Recently a new four-dimensional non relativistic renormalizable theory of gravity was proposed by Horava. This gravity reduces to Einstein gravity at large distances. In this paper by using the new action for gravity we present different toroidal solutions to the equations of motion. Our solutions describe the near horizon geometry with slow rotating parameter.
Performance Measurement of Revolving Vane Compressor
Tan, Kok Ming; Choo, Wei Chong; Chee, Michael; Law, Ken; Iswan, Ismail; Ooi, Kim Tiow
2014-01-01
Over the years, rotary compressors have gained popularity and widely used in household and automotive air-conditioning applications because of the compact nature and silent characteristics. By engaging a revolutionary concept to elevate the rotary compressor efficiency, a novel compressor mechanism, named the Revolving Vane compressor is invented. The prototype R134a compressor was designed, fabricated, instrumented and tested. Compressor tests were conducted for varying suction pressures, su...
Intrinsic rotation of toroidally confined magnetohydrodynamics.
Morales, Jorge A; Bos, Wouter J T; Schneider, Kai; Montgomery, David C
2012-10-26
The spatiotemporal self-organization of viscoresistive magnetohydrodynamics in a toroidal geometry is studied. Curl-free toroidal magnetic and electric fields are imposed. It is observed in our simulations that a flow is generated, which evolves from dominantly poloidal to toroidal when the Lundquist numbers are increased. It is shown that this toroidal organization of the flow is consistent with the tendency of the velocity field to align with the magnetic field. Up-down asymmetry of the geometry causes the generation of a nonzero toroidal angular momentum. PMID:23215195
Design and Simulation of Toroidal Twister Model
Institute of Scientific and Technical Information of China (English)
TIAN Huifang; LIN Xizhen; ZENG Qinqin
2006-01-01
Toroidal composite vessel winded with fiber is a new kind of structural pressure vessels, which not only has high structure efficiency of compound materials pressure vessel, good security and so on, but also has special shape and the property of utilizing toroidal space, and the prospect of the application of toroidal composite vessel winded with fiber is extremely broad. By introducing parameters establishment of toroidal vessel and elaborating the principle of filament winding for toroidal vessel, the design model of filament winding machine for toroidal vessel has been introduced, and the design model has been dynamically simulated by the software of ADAMS, which will give more referrence for the design of real toroidal vessel twister.
Directory of Open Access Journals (Sweden)
Gulyaev P. V.
2016-05-01
Full Text Available The article is devoted to the development of a compressor type ozonator. It describes the design of a high-productivity compressor ozone generator, which can be used for industrial decontamination of mixed feeds, water, milk, and in the system of presowing treatment of seeds. This construction allows generating ozone with high concentration to 5 g/m3 at high feed air or oxygen from the compressor station (up to 2000 l/min. The article describes the design of the basic elements of tubular ozone generator, examines the factors influencing the productivity of the ozonator. The proposed mathematical model allows calculating the productivity of the ozonator when considering multiple influencing factors. These factors take into account: the parameters of supply voltage, such as the magnitude and frequency of the supply voltage; the configuration and geometrical parameters of electrodes such as, the area of the electrodes, the configuration of the surface of the electrodes and distance between electrodes; parameters dielectric barrier; and the transported gas parameters such as volume, temperature, pressure and composition. Special attention is paid to the design of the electrodes made of woven wire mesh with mesh sizes from 1.5×1.5 to 2.0×2.0 mm. It is noted, that such electrodes allow obtaining the maximum productivity of an ozonator, and they do not lead to overheating of the dielectric barrier, and do not output down the generator. In the same way, the article presents the results of the mathematical modeling of ozone generator productivity while changing various factors
Centrifugal-reciprocating compressor
Higa, W. H. (Inventor)
1984-01-01
A centrifugal compressor is described which includes at least one pair of cylinders arranged in coaxial alignment and supported for angular displacement about a common axis of rotation normally disecting a common longitudinal axis of symmetry for the cylinders. The cylinders are characterized by ported closures located at the mutually remote ends thereof through which the cylinders are charged and discharged, and a pair of piston heads seated within the cylinders and supported for floating displacement in compressive strokes in response to unidirectional angular displacement imparted to the cylinders.
Practical experience with unstable compressors
Malanoski, S. B.
1980-01-01
Using analytical mathematical modeling techniques for the system components, an attempt is made to gauge the destabilizing effects in a number of compressor designs. In particular the overhung (or cantilevered) compressor designs and the straddle-mounted (or simply supported) compressor designs are examined. Recommendations are made, based on experiences with stable and unstable compressors, which can be used as guides in future designs. High and low pressure compressors which operate well above their fundamental rotor-bearing lateral natural frequencies can suffer from destructive subsynchronous vibration. Usually the elements in the system design which contribute to this vibration, other than the shafting and the bearings, are the seals (both gas labyrinth and oil breakdown bushings) and the aerodynamic components.
QRFXFreeze: Queryable Compressor for RFX.
Senthilkumar, Radha; Nandagopal, Gomathi; Ronald, Daphne
2015-01-01
The verbose nature of XML has been mulled over again and again and many compression techniques for XML data have been excogitated over the years. Some of the techniques incorporate support for querying the XML database in its compressed format while others have to be decompressed before they can be queried. XML compression in which querying is directly supported instantaneously with no compromise over time is forced to compromise over space. In this paper, we propose the compressor, QRFXFreeze, which not only reduces the space of storage but also supports efficient querying. The compressor does this without decompressing the compressed XML file. The compressor supports all kinds of XML documents along with insert, update, and delete operations. The forte of QRFXFreeze is that the textual data are semantically compressed and are indexed to reduce the querying time. Experimental results show that the proposed compressor performs much better than other well-known compressors. PMID:26065027
Prospects for toroidal fusion reactors
International Nuclear Information System (INIS)
Work on the International Thermonuclear Experimental Reactor (ITER) tokamak has refined understanding of the realities of a deuterium-tritium (D-T) burning magnetic fusion reactor. An ITER-like tokamak reactor using ITER costs and performance would lead to a cost of electricity (COE) of about 130 mills/kWh. Advanced tokamak physics to be tested in the Toroidal Physics Experiment (TPX), coupled with moderate components in engineering, technology, and unit costs, should lead to a COE comparable with best existing fission systems around 60 mills/kWh. However, a larger unit size, ∼2000 MW(e), is favored for the fusion system. Alternative toroidal configurations to the conventional tokamak, such as the stellarator, reversed-field pinch, and field-reversed configuration, offer some potential advantage, but are less well developed, and have their own challenges
Classification of symmetric toroidal orbifolds
Energy Technology Data Exchange (ETDEWEB)
Fischer, Maximilian; Ratz, Michael; Torrado, Jesus [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Vaudrevange, Patrick K.S. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2012-09-15
We provide a complete classification of six-dimensional symmetric toroidal orbifolds which yield N{>=}1 supersymmetry in 4D for the heterotic string. Our strategy is based on a classification of crystallographic space groups in six dimensions. We find in total 520 inequivalent toroidal orbifolds, 162 of them with Abelian point groups such as Z{sub 3}, Z{sub 4}, Z{sub 6}-I etc. and 358 with non-Abelian point groups such as S{sub 3}, D{sub 4}, A{sub 4} etc. We also briefly explore the properties of some orbifolds with Abelian point groups and N=1, i.e. specify the Hodge numbers and comment on the possible mechanisms (local or non-local) of gauge symmetry breaking.
TFTR toroidal field coil design
International Nuclear Information System (INIS)
The design of the Tokamak Fusion Test Reactor (TFTR) Toroidal Field (TF) magnetic coils is described. The TF coil is a 44-turn, spiral-wound, two-pancake, water-cooled configuration which, at a coil current of 73.3 kiloamperes, produces a 5.2-Tesla field at a major radius of 2.48 meters. The magnetic coils are installed in titanium cases, which transmit the loads generated in the coils to the adjacent supporting structure. The TFTR utilizes 20 of these coils, positioned radially at 180 intervals, to provide the required toroidal field. Because it is very highly loaded and subject to tight volume constraints within the machine, the coil presents unique design problems. The TF coil requirements are summarized, the coil configuration is described, and the problems highlighted which have been encountered thus far in the coil design effort, together with the development tests which have been undertaken to verify the design
Time-Dependent of Accretion Flow with Toroidal Magnetic Field
Khesali, Alireza
2008-01-01
In the present study time evolution of quasi-spherical polytropic accretion flow with toroidal magnetic field was investigated. The study especially focused the astrophysically important case in which the adiabatic exponent $\\gamma=5/3$. In this scenario, it was assumed that the angular momentum transport is due to viscous turbulence and used $\\alpha$-prescription for kinematic coefficient of viscosity. The equations of accretion flow are solved in a simplified one-dimensional model that neglects the latitudinal dependence of the flow. In order to solve the integrated equations which govern the dynamical behavior of the accretion flow, self-similar solution was used. The solution provides some insight into the dynamics of quasi-spherical accretion flow and avoids many of the strictures of the steady self-similar solution. The effect of the toroidal magnetic field is considered with additional variable $\\beta[=p_{mag}/p_{gas}]$, where $p_{mag}$ and $p_{gas}$ are the magnetic and gas pressure, respectively. The...
Transporting the first ATLAS toroid
Maximilien Brice
2004-01-01
The first coil for the ATLAS toroid magnet is transported from its assembly hall at the CERN Meyrin site to the storage hall above the ATLAS cavern. This involves driving the massive transportation vehicle first through the Meyrin site and then across a main road only metres from the France-Swiss border. Eight magnets in total will be transported in this way before being lowered into the experimental cavern where they will be mounted in a huge ring surrounding the detector.
Adiabatic theory for the bipolaron
Energy Technology Data Exchange (ETDEWEB)
Lakhno, V.D. (Institute of Mathematical Problems of Biology, Russian Academy of Sciences, Pushchino Moscow Region, 142292 (Russian Federation))
1995-02-01
A translation-invariant adiabatic theory is constructed for the bipolaron. It is shown that motions in the bipolaron are divided: the relative electron coordinates describe fast electron oscillations in the induced polarization well and the center of mass coordinates represent slow electron movement followed by polarization. Nonlinear differential bipolaron equations are derived which are asymptotically exact in the adiabatic limit. Particlelike solutions of these equations correspond to the bipolaron bound state. The exact solution yields the value of the ion critical parameter [eta]=0.31 for which the bipolaron state is stable, where [eta]=[epsilon][sub [infinity
Optimizing adiabaticity in quantum mechanics
MacKenzie, R; Renaud-Desjardins, L
2011-01-01
A condition on the Hamiltonian of a time-dependent quantum mechanical system is derived which, if satisfied, implies optimal adiabaticity (defined below). The condition is expressed in terms of the Hamiltonian and in terms of the evolution operator related to it. Since the latter depends in a complicated way on the Hamiltonian, it is not yet clear how the condition can be used to extract useful information about the optimal Hamiltonian. The condition is tested on an exactly-soluble time-dependent problem (a spin in a magnetic field), where perfectly adiabatic evolution can be easily identified.
Magnetic Properties of 3D Printed Toroids
Bollig, Lindsey; Otto, Austin; Hilpisch, Peter; Mowry, Greg; Nelson-Cheeseman, Brittany; Renewable Energy; Alternatives Lab (REAL) Team
Transformers are ubiquitous in electronics today. Although toroidal geometries perform most efficiently, transformers are traditionally made with rectangular cross-sections due to the lower manufacturing costs. Additive manufacturing techniques (3D printing) can easily achieve toroidal geometries by building up a part through a series of 2D layers. To get strong magnetic properties in a 3D printed transformer, a composite filament is used containing Fe dispersed in a polymer matrix. How the resulting 3D printed toroid responds to a magnetic field depends on two structural factors of the printed 2D layers: fill factor (planar density) and fill pattern. In this work, we investigate how the fill factor and fill pattern affect the magnetic properties of 3D printed toroids. The magnetic properties of the printed toroids are measured by a custom circuit that produces a hysteresis loop for each toroid. Toroids with various fill factors and fill patterns are compared to determine how these two factors can affect the magnetic field the toroid can produce. These 3D printed toroids can be used for numerous applications in order to increase the efficiency of transformers by making it possible for manufacturers to make a toroidal geometry.
Elementary examples of adiabatic invariance
Energy Technology Data Exchange (ETDEWEB)
Crawford, F.S. (Physics Department, University of California, Berkeley, CA (USA) Lawrence Berkeley Laboratory, University of California, Berkeley, CA 94720 (USA))
1990-04-01
Simple classical one-dimensional systems subject to adiabatic (gradual) perturbations are examined. The first examples are well known: the adiabatic invariance of the product {ital E}{tau} of energy {ital E} and period {tau} for the simple pendulum and for the simple harmonic oscillator. Next, the adiabatic invariants of the vertical bouncer are found---a ball bouncing elastically from the floor of a rising elevator having slowly varying velocity and acceleration. These examples lead to consideration of adiabatic invariance for one-dimensional systems with potentials of the form {ital V}={ital ax}{sup {ital n}}, with {ital a}={ital a}({ital t}) slowly varying in time. Then, the horizontal bouncer is considered---a mass sliding on a smooth floor, bouncing back and forth between two impenetrable walls, one of which is slowly moving. This example is generalized to a particle in a bound state of a general potential with one slowly moving turning point.'' Finally, circular motion of a charged particle in a magnetic field slowly varying in time under three different configurations is considered: (a) a free particle in a uniform field; (b) a free particle in a nonuniform betatron'' field; and (c) a particle constrained to a circular orbit in a uniform field.
Transitionless driving on adiabatic search algorithm
Energy Technology Data Exchange (ETDEWEB)
Oh, Sangchul, E-mail: soh@qf.org.qa [Qatar Environment and Energy Research Institute, Qatar Foundation, Doha (Qatar); Kais, Sabre, E-mail: kais@purdue.edu [Qatar Environment and Energy Research Institute, Qatar Foundation, Doha (Qatar); Department of Chemistry, Department of Physics and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States)
2014-12-14
We study quantum dynamics of the adiabatic search algorithm with the equivalent two-level system. Its adiabatic and non-adiabatic evolution is studied and visualized as trajectories of Bloch vectors on a Bloch sphere. We find the change in the non-adiabatic transition probability from exponential decay for the short running time to inverse-square decay in asymptotic running time. The scaling of the critical running time is expressed in terms of the Lambert W function. We derive the transitionless driving Hamiltonian for the adiabatic search algorithm, which makes a quantum state follow the adiabatic path. We demonstrate that a uniform transitionless driving Hamiltonian, approximate to the exact time-dependent driving Hamiltonian, can alter the non-adiabatic transition probability from the inverse square decay to the inverse fourth power decay with the running time. This may open up a new but simple way of speeding up adiabatic quantum dynamics.
Compressor performance aerodynamics for the user
Gresh, Theodore
2001-01-01
Compressor Performance is a reference book and CD-ROM for compressor design engineers and compressor maintenance engineers, as well as engineering students. The book covers the full spectrum of information needed for an individual to select, operate, test and maintain axial or centrifugal compressors. It includes basic aerodynamic theory to provide the user with the ""how's"" and ""why's"" of compressor design. Maintenance engineers will especially appreciate the troubleshooting guidelines offered. Includes many example problems and reference data such as gas propert
Empirical Design Considerations for Industrial Centrifugal Compressors
Cheng Xu; Amano, Ryoichi S.
2012-01-01
Computational Fluid Dynamics (CFD) has been extensively used in centrifugal compressor design. CFD provides further optimisation opportunities for the compressor design rather than designing the centrifugal compressor. The experience-based design process still plays an important role for new compressor developments. The wide variety of design subjects represents a very complex design world for centrifugal compressor designers. Therefore, some basic information for centrifugal design is still ...
Characterization of Multiflux Axial Compressors
International Nuclear Information System (INIS)
In the present work the results of analytical models of performance are compared with experimental data acquired in the multi flux axial compressor test facility, built in The Pilcaniyeu Technological Complex for the SIGMA project.We describe the experimental circuit and the data of the dispersion inside the axial compressor obtained using a tracer gas through one of the annular inlets.The attained results can be used to validate the design code for the multi flux axial compressors and SIGMA industrial plant
Beam Transport in Toroidal Magnetic Field
Joshi, N; Meusel, O; Ratzinger, U
2016-01-01
The concept of a storage ring with toroidal magnetic field was presented in the two previous EPAC conferences. Here we report the first results of experiments performed with beam transport in toroidal magnetic fields and details of the injection system. The beam transport experiments were carried out with 30 degree toroidal segments with an axial magnetic field of 0.6T. The multi turn injection system relies on a transverse injection coil together with an electric kicker system.
Digital Waveguide Adiabatic Passage Part 1: Theory
Vaitkus, Jesse A; Greentree, Andrew D
2016-01-01
Spatial adiabatic passage represents a new way to design integrated photonic devices. In conventional adiabatic passage designs require smoothly varying waveguide separations. Here we show modelling of adiabatic passage devices where the waveguide separation is varied digitally. Despite digitisation, our designs show robustness against variations in the input wavelength and refractive index contrast of the waveguides relative to the cladding. This approach to spatial adiabatic passage opens new design strategies and hence the potential for new photonics devices.
Electrochemical Hydrogen Compressor
Energy Technology Data Exchange (ETDEWEB)
David P. Bloomfield; Brian S. MacKenzie
2006-05-01
The Electrochemical Hydrogen Compressor EHC was evaluated against DOE applications for compressing hydrogen at automobile filling stations, in future hydrogen pipelines and as a commercial replacement for conventional diaphragm hydrogen compressors. It was also evaluated as a modular replacement for the compressors used in petrochemical refineries. If the EHC can be made inexpensive, reliable and long lived then it can satisfy all these applications save pipelines where the requirements for platinum catalyst exceeds the annual world production. The research performed did not completely investigate Molybdenum as a hydrogen anode or cathode, it did show that photoetched 316 stainless steel is inadequate for an EHC. It also showed that: molybdenum bipolar plates, photochemical etching processes, and Gortex Teflon seals are too costly for a commercial EHC. The use of carbon paper in combination with a perforated thin metal electrode demonstrated adequate anode support strength, but is suspect in promoting galvanic corrosion. The nature of the corrosion mechanisms are not well understood, but locally high potentials within the unit cell package are probably involved. The program produced a design with an extraordinary high cell pitch, and a very low part count. This is one of the promising aspects of the redesigned EHC. The development and successful demonstration of the hydraulic cathode is also important. The problem of corrosion resistant metal bipolar plates is vital to the development of an inexpensive, commercial PEM fuel cell. Our research suggests that there is more to the corrosion process in fuel cells and electrochemical compressors than simple, steady state, galvanic stability. It is an important area for scientific investigation. The experiments and analysis conducted lead to several recommended future research directions. First, we need a better understanding of the corrosion mechanisms involved. The diagnosis of experimental cells with titration to
Dual capacity reciprocating compressor
Wolfe, Robert W.
1984-01-01
A multi-cylinder compressor 10 particularly useful in connection with northern climate heat pumps and in which different capacities are available in accordance with reversing motor 16 rotation is provided with an eccentric cam 38 on a crank pin 34 under a fraction of the connecting rods, and arranged for rotation upon the crank pin between opposite positions 180.degree. apart so that with cam rotation on the crank pin such that the crank throw is at its normal maximum value all pistons pump at full capacity, and with rotation of the crank shaft in the opposite direction the cam moves to a circumferential position on the crank pin such that the overall crank throw is zero. Pistons 24 whose connecting rods 30 ride on a crank pin 36 without a cam pump their normal rate with either crank rotational direction. Thus a small clearance volume is provided for any piston that moves when in either capacity mode of operation.
Pellet injection and toroidal confinement
International Nuclear Information System (INIS)
The proceedings of a technical committee meeting on pellet injection and toroidal confinement, held in Gut Ising, Federal Republic of Germany, 24-26 October, 1988, are given in this report. Most of the major fusion experiments are using pellet injectors; these were reported at this meeting. Studies of confinement, which is favorably affected, impurity transport, radiative energy losses, and affects on the ion temperature gradient instability were given. Studies of pellet ablation and effects on plasma profiles were presented. Finally, several papers described present and proposed injection guns. Refs, figs and tabs
Toroidal Theory of MHD Instabilities
International Nuclear Information System (INIS)
We continue with the adventures of the Alfven wave and its two magnetosonic companions as they travel in the curved space of magnetic surfaces and field lines (Sec. 2), find themselves trapped in singularities of an unprecedented richness (Sec. 3), decide to get themselves better maps of the landscape to do the required twisting while some of their youthful energy is leaking away (Sec. 4), cause trouble at the edge of a powerful empire (Sec. 5), and finally see the light in a distant future (Sec. 6). Needed on the trip are the evolution equations of both ideal and resistive MHD 'derived' in reference [1], the solutions to the toroidal equilibrium equations discussed in reference [2], the general background on spectral theory of inhomogeneous plasmas presented in reference [3], which is extended in the two directions of toroidal geometry and resistivity in this lecture [4]. This leads to such intricate dynamics that numerical techniques are virtually the only way to proceed. This aspect is further elaborated in reference [5] on numerical techniques
A one kPa centrifugal cold compressor for the 1.8 K helium refrigeration system of LHC
Saji, N; Yoshinaga, S; Itoh, K; Nogaku, T; Bézaguet, Alain-Arthur; Casas-Cubillos, J; Lebrun, P; Tavian, L
1998-01-01
CERN placed an order for a cold compressor prototype (CCP) with IHI for the LHC project. The CCP is supported by the oil-free magnetic bearings, driven by an induction motor. The compressor has the characteristics of high efficiency and wide operation range, thanks to the optimum design for the impeller and diffuser. The result of the performance tests at CERN showed that static heat in-leaks could be controlled at approx. 7.3 W, and an adiabatic efficiency is 75at a nominal flow of 18 g's with suction temperature of 4.4 K and suction pressure of 1 kPa. (4 refs).
Global kink and ballooning modes in high-beta systems and stability of toroidal drift modes
International Nuclear Information System (INIS)
A numerical code (HBT) has been developed which solves for the equilibrium, global stability and high-n stability of plasmas with arbitrary cross-section. Various plasmas are analysed for their stability to these modes in the high-beta limit. Screw-pinch equilibria are stable to high-n ballooning modes up to betas of 18%. The eigenmode equation for drift waves is analysed numerically. The toroidal branch is shown to be destabilized by the non-adiabatic response of trapped and circulating particles. (author)
Design and application of robust rf pulses for toroid cavity NMR spectroscopy
Skinner, Thomas E; Woelk, Klaus; Gershenzon, Naum I; Glaser, Steffen J
2010-01-01
We present robust radio frequency (rf) pulses that tolerate a factor of six inhomogeneity in the B1 field, significantly enhancing the potential of toroid cavity resonators for NMR spectroscopic applications. Both point-to-point (PP) and unitary rotation (UR) pulses were optimized for excitation, inversion, and refocusing using the gradient ascent pulse engineering (GRAPE) algorithm based on optimal control theory. In addition, the optimized parameterization (OP) algorithm applied to the adiabatic BIR-4 UR pulse scheme enabled ultra-short (50 microsec) pulses with acceptable performance compared to standard implementations. OP also discovered a new class of non-adiabatic pulse shapes with improved performance within the BIR-4 framework. However, none of the OP-BIR4 pulses are competitive with the more generally optimized UR pulses. The advantages of the new pulses are demonstrated in simulations and experiments. In particular, the DQF COSY result presented here represents the first implementation of 2D NMR sp...
Fast Dump of the ATLAS Toroids
Dudarev, A; Volpini, Giovanni; Dudarev, Alexey; Kate, Herman Ten
2010-01-01
The toroidal magnet system of the ATLAS Detector at CERN consists of a Barrel Toroid (BT) and two End Cap Toroids (ECT-A and ECT-C). Each toroid is built up from eight racetrack coils wound with an aluminum stabilized NbTi conductor and indirectly cooled by forced flow liquid helium. The three toroids operate in series at 20.5 kA with a total stored energy of 1.5 GJ. In order to verify the reliability and effectiveness of the quench protection system, series of fast dump tests have been performed first of the single toroids and finally of the entire toroidal magnet system. In this paper a model to simulate the fast dump of the ATLAS toroids in single mode operation and in full system configuration is presented. The model is validated through comparison with measured data extracted from the ramp-and-quench runs. The calculated energy dissipation in the various coils is in very good agreement (within 1-2\\%) with the enthalpy changes estimated from the temperature measurements of the different parts of the cold ...
Electrostatics of a Family of Conducting Toroids
Lekner, John
2009-01-01
An exact solution is found for the electrostatic potential of a family of conducting charged toroids. The toroids are characterized by two lengths "a" and "b", with "a" greater than or equal to "2b". They are closed, with no hole in the "doughnut". The results are obtained by considering the potential of two equal charges, displaced from the…
Toroidal Alfven wave stability in ignited tokamaks
Energy Technology Data Exchange (ETDEWEB)
Cheng, C.Z.; Fu, G.Y.; Van Dam, J.W.
1989-01-01
The effects of fusion-product alpha particles on the stability of global-type shear Alfven waves in an ignited tokamak plasma are investigated in toroidal geometry. Finite toroidicity can lead to stabilization of the global Alfven eigenmodes, but it induces a new global shear Alfven eigenmodes, which is strongly destabilized via transit resonance with alpha particles. 8 refs., 2 figs.
Compressor bleed cooling fluid feed system
Donahoo, Eric E; Ross, Christopher W
2014-11-25
A compressor bleed cooling fluid feed system for a turbine engine for directing cooling fluids from a compressor to a turbine airfoil cooling system to supply cooling fluids to one or more airfoils of a rotor assembly is disclosed. The compressor bleed cooling fluid feed system may enable cooling fluids to be exhausted from a compressor exhaust plenum through a downstream compressor bleed collection chamber and into the turbine airfoil cooling system. As such, the suction created in the compressor exhaust plenum mitigates boundary layer growth along the inner surface while providing flow of cooling fluids to the turbine airfoils.
Toroidal Vortices in Resistive Magnetohydrodynamic Equilibria
Montgomery, D C; Li, S; Montgomery, David; Bates, Jason W.; Li, Shuojun
1996-01-01
Resistive steady states in toroidal magnetohydrodynamics (MHD), where Ohm's law must be taken into account, differ considerably from ideal ones. Only for special (and probably unphysical) resistivity profiles can the Lorentz force, in the static force-balance equation, be expressed as the gradient of a scalar and thus cancel the gradient of a scalar pressure. In general, the Lorentz force has a curl directed so as to generate toroidal vorticity. Here, we calculate, for a collisional, highly viscous magnetofluid, the flows that are required for an axisymmetric toroidal steady state, assuming uniform scalar resistivity and viscosity. The flows originate from paired toroidal vortices (in what might be called a ``double smoke ring'' configuration), and are thought likely to be ubiquitous in the interior of toroidally driven magnetofluids of this type. The existence of such vortices is conjectured to characterize magnetofluids beyond the high-viscosity limit in which they are readily calculable.
Toroidal effects on drift wave turbulence
Energy Technology Data Exchange (ETDEWEB)
LeBrun, M.J.; Tajima, T.; Gray, M.G.; Furnish, G.; Horton, W.
1992-09-23
The universal drift instability and other drift instabilities driven by density and temperature gradients in a toroidal system are investigated in both linear and nonlinear regimes via particle simulation. Runs in toroidal and cylindrical geometry show dramatic differences in plasma behavior, primarily due to the toroidicity-induced coupling of rational surfaces through the poloidal mode number m. In the toroidal system studied, the eigenmodes are seen to possess (i) an elongated, nearly global radial extent (ii) a higher growth rate than in the corresponding cylindrical system, (iii) an eigenfrequency nearly constant with radius, (iv) a global temperature relaxation and enhancement of thermal heat conduction. Most importantly, the measured Xi shows an increase with radius and an absolute value on the order of that observed in experiment. On the basis of our observations, we argue that the increase in Xi with radius observed in experiment is caused by the global nature of heat convection in the presence of toroidicity-induced mode coupling.
Development of Toroidal Core Transformers
Energy Technology Data Exchange (ETDEWEB)
Leon, Francisco
2014-05-31
The original objective of this project was to design, build and test a few prototypes of singlephase dry-type distribution transformers of 25 kVA, 2.4 kV primary to 120 V transformers using cores made of a continuous steel strip shaped like a doughnut (toroid). At different points during the development of the project, the scope was enhanced to include the more practical case of a 25 kVA transformer for a 13.8 kV primary system voltage. Later, the scope was further expanded to design and build a 50 kVA unit to transformer voltage from 7.62 kV to 2x120 V. This is a common transformer used by Con Edison of New York and they are willing to test it in the field. The project officially started in September 2009 and ended in May 2014. The progress was reported periodically to DOE in eighteen quarterly reports. A Continuation Application was submitted to DOE in June 2010. In May 2011 we have requested a non-cost extension of the project. In December 2011, the Statement of Project Objectives (SOPO) was updated to reflect the real conditions and situation of the project as of 2011. A second Continuation Application was made and funding was approved in 2013 by DOE and the end date was extended to May 2014.The technical challenges that were overcome in this project include: the development of the technology to pass the impulse tests, derive a model for the thermal performance, produce a sound mechanical design, and estimate the inrush current. However, the greatest challenge that we faced during the development of the project was the complications of procuring the necessary parts and materials to build the transformers. The actual manufacturing process is relatively fast, but getting all parts together is a very lengthy process. The main products of this project are two prototypes of toroidal distribution transformers of 7.62 kV (to be used in a 13.8 kV system) to 2x120 V secondary (standard utilization voltage); one is rated at 25 kVA and the other at 50 kVA. The 25 k
Li, Dafa
2016-05-01
The adiabatic theorem was proposed about 90 years ago and has played an important role in quantum physics. The quantitative adiabatic condition constructed from eigenstates and eigenvalues of a Hamiltonian is a traditional tool to estimate adiabaticity and has proven to be the necessary and sufficient condition for adiabaticity. However, recently the condition has become a controversial subject. In this paper, we list some expressions to estimate the validity of the adiabatic approximation. We show that the quantitative adiabatic condition is invalid for the adiabatic approximation via the Euclidean distance between the adiabatic state and the evolution state. Furthermore, we deduce general necessary and sufficient conditions for the validity of the adiabatic approximation by different definitions.
NCSX Toroidal Field Coil Design
Energy Technology Data Exchange (ETDEWEB)
Kalish, M.; Rushinski, J.; Myatt, L.; Brooks, A.; Dahlgren, F.; Chrzanowski, J.; Reiersen, W.; Freudenberg, K.
2005-10-07
The National Compact Stellarator Experiment (NCSX) is an experimental device whose design and construction is underway at the Department of Energy's Princeton Plasma Physics Laboratory (PPPL). The primary coil systems for the NCSX device consist of the twisted plasma-shaping Modular Coils, the Poloidal Field Coils, and the Toroidal Field (TF) Coils. The TF Coils are D-shaped coils wound from hollow copper conductor, and vacuum impregnated with a glass-epoxy resin system. There are 18 identical, equally spaced TF coils providing 1/R field at the plasma. They operate within a cryostat, and are cooled by LN2, nominally, to 80K. Wedge shaped castings are assembled to the inboard face of these coils, so that inward radial loads are reacted via the nesting of each of the coils against their adjacent partners. This paper outlines the TF Coil design methodology, reviews the analysis results, and summarizes how the design and analysis support the design requirements.
Designing compressor installations for reliability
Energy Technology Data Exchange (ETDEWEB)
Greenfield, S.D.; Howes, B.C.; Robinson, A.; Eckert, W.
2000-07-01
The best approach to the design of a new centrifugal or reciprocating compressor that will ensure reliability, performance and maintenance of the equipment involves the use of analytical tools. One must understand the sources of the potential problems and consequences along with the availability of design services. At that point risk assessment can be performed. The objective is to keep pulsations, vibration levels and dynamic stresses low, so as to minimally impact on the performance and reliability and maintain control over costs. The consideration of forcing functions, natural frequencies, mode shapes and dynamic stiffness is essential, as they apply to rotor dynamics, torsional vibration, piping vibration, skid and foundation vibration. It also applies to the interaction of the piping geometry with pressure pulsations which can produce significant forces and stresses for both reciprocating and centrifugal compressors and lead to a decrease in performance. The authors described the considerations that help determine which analytical tool is best to develop a computer model that can be used to avoid problems. Three cases were introduced to better illustrate the advantages of adequate design modeling and optimization. Each case deals with a different problem: (1) a lateral critical and a structural resonance in a centrifugal compressor installation, (2) a piping failure in a reciprocating compressor installation, and (3) a torsional failure in a reciprocating compressor installation. 1 ref., 2 tabs., 3 figs.
Efficient Vent Unloading of Air Compressors
Muhonen, Alvin J.
1987-01-01
Method for unloading one-and two-stage reciprocating air compressors increases energy efficiency and inhibits deterioration of components. In new unloader configuration, compressor vented to atmosphere on downstream side. Method implemented expeditiously as modification of existing systems.
Empirical Design Considerations for Industrial Centrifugal Compressors
Directory of Open Access Journals (Sweden)
Cheng Xu
2012-01-01
Full Text Available Computational Fluid Dynamics (CFD has been extensively used in centrifugal compressor design. CFD provides further optimisation opportunities for the compressor design rather than designing the centrifugal compressor. The experience-based design process still plays an important role for new compressor developments. The wide variety of design subjects represents a very complex design world for centrifugal compressor designers. Therefore, some basic information for centrifugal design is still very important. The impeller is the key part of the centrifugal stage. Designing a highly efficiency impeller with a wide operation range can ensure overall stage design success. This paper provides some empirical information for designing industrial centrifugal compressors with a focus on the impeller. A ported shroud compressor basic design guideline is also discussed for improving the compressor range.
Positive Displacement Compressor Technology for Refrigeration
Nagatomo, Shigemi
Trends of compressor technologies for refrigerators, freezers and condensing units are presented in this paper. HFC refrigerants such as R134a and R404C are promising candidates as an altemative for R12. Performance of reciprocating and rotary compressors in the operation with R134A is described. In addition, compressor technologies such as efficiency improvement are described in the cases of reciprocating, rotary and scroll compressors.
Investigation Of Compressor Heat Dispersion Model
Shi, Da; Tao, Hong; Yang, Min
2014-01-01
This paper represents a method for calculate the heat dissipation capacity and discharge temperature for rotary compressors. The proposed heat dissipation model is used for calculating heat dissipating capacity of compressor in forced-convection/natural-convection and radiation heat transfer mode. The comparison between calculated result and experimental result for both constant speed compressors and variable speed compressors shows that the average heat dissipating capacity error is below 20...
Meridional Considerations of the Centrifugal Compressor Development
Xu, C.; Amano, R. S.
2012-01-01
Centrifugal compressor developments are interested in using optimization procedures that enable compressor high efficiency and wide operating ranges. Recently, high pressure ratio and efficiency of the centrifugal compressors require impeller design to pay attention to both the blade angle distribution and the meridional profile. The geometry of the blades and the meridional profile are very important contributions of compressor performance and structure reliability. This paper presents some ...
New coatings extend compressor service life
Energy Technology Data Exchange (ETDEWEB)
Chow, R. [Novacor Chemicals, Red Deer, Alberta (Canada); McMordie, B. [Sermatech International, Inc., Limerick, PA (United States); Wiegand, R. [Elliot Company, Jennetta, PA (United States)
1995-10-01
To lengthen production runs, a Canadian ethylene operator experimented with a coating system to protect a critical compressor`s rotor from hydrocarbon-polymerization/fouling. In ethylene manufacturing, compressor fouling is an accepted ``fact of life.`` Past attempts to minimize fouling in the crack-gas compression train were unsuccessful or marginally cost-effective. Applying protective coatings to a critical-service ethylene compressor rotor slowed oiling, thus lengthening the production run time by one year.
40 CFR 63.1012 - Compressor standards.
2010-07-01
... measured during each compliance test. (g) Reciprocating compressor exemption. Any existing reciprocating... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Compressor standards. 63.1012 Section... Emission Standards for Equipment Leaks-Control Level 1 § 63.1012 Compressor standards. (a)...
Small Radial Compressors: Aerodynamic Design and Analysis
K. A. R. Ismail; Rosolen, C. V. A. G.; Benevenuto, F. J.; Lucato, D.
1998-01-01
This paper presents a computational procedure for the analysis of steady one-dimensional centrifugal compressor. The numerical model is based on the conservation principles of mass, momentum and energy, and has been utilized to predict the operational and aerodynamic characteristics of a small centrifugal compressor as well as determining the performance and geometry of compressor blades, both straight and curved.
Small Radial Compressors: Aerodynamic Design and Analysis
Directory of Open Access Journals (Sweden)
K. A. R. Ismail
1998-01-01
Full Text Available This paper presents a computational procedure for the analysis of steady one-dimensional centrifugal compressor. The numerical model is based on the conservation principles of mass, momentum and energy, and has been utilized to predict the operational and aerodynamic characteristics of a small centrifugal compressor as well as determining the performance and geometry of compressor blades, both straight and curved.
On the topology of adiabatic passage
Yatsenko, L P; Jauslin, H R
2002-01-01
We examine the topology of eigenenergy surfaces characterizing the population transfer processes based on adiabatic passage. We show that this topology is the essential feature for the analysis of the population transfers and the prediction of its final result. We reinterpret diverse known processes, such as stimulated Raman adiabatic passage (STIRAP), frequency-chirped adiabatic passage and Stark-chirped rapid adiabatic passage (SCRAP). Moreover, using this picture, we display new related possibilities of transfer. In particular, we show that we can selectively control the level which will be populated in STIRAP process in Lambda or V systems by the choice of the peak amplitudes or the pulse sequence.
Multiple-applications of Accelerated Compact Toroid Injection for MFE
Hwang, David; Horton, Robert; Evans, Russell; Liu, Fei; Zhu, Ben; Hong, Sean; Buchenauer, Dean
2010-11-01
The CTIX experiment has explored the potential applications of launching a fast moving magnetized compact toroid for Magnetic Fusion experiments. These applications include central fueling of a MFE device such as tokamaks, stellarators, etc. At present, the UC Davis CTIX accelerator has achieved densities at mid to upper 10^15 per cc, at speeds reaching over 200 km/sec. In order to meet the parameters of even larger fusion devices, the technology of the accelerator needs to incorporate the latest plasma wall interaction findings. As a result of the next step in CT development, UC Davis will be collaborating with the Fusion Technology group at Sandia National Laboratory in Livermore California. We will be designing new plasmas facing electrodes that can reduce electrode impurities and increase electrode lifetime. In addition to producing high density CTs, we will include the updated conical compression results from our previous installed drift section compressor. In addition of the MFE applications, the ability to enhance the CT density, fields as well as speed can be useful to other fusion areas such as MIF, etc.
Design and optimization of a single stage centrifugal compressor for a solar dish-Brayton system
Wang, Yongsheng; Wang, Kai; Tong, Zhiting; Lin, Feng; Nie, Chaoqun; Engeda, Abraham
2013-10-01
According to the requirements of a solar dish-Brayton system, a centrifugal compressor stage with a minimum total pressure ratio of 5, an adiabatic efficiency above 75% and a surge margin more than 12% needs to be designed. A single stage, which consists of impeller, radial vaned diffuser, 90° crossover and two rows of axial stators, was chosen to satisfy this system. To achieve the stage performance, an impeller with a 6:1 total pressure ratio and an adiabatic efficiency of 90% was designed and its preliminary geometry came from an in-house one-dimensional program. Radial vaned diffuser was applied downstream of the impeller. Two rows of axial stators after 90° crossover were added to guide the flow into axial direction. Since jet-wake flow, shockwave and boundary layer separation coexisted in the impeller-diffuser region, optimization on the radius ratio of radial diffuser vane inlet to impeller exit, diffuser vane inlet blade angle and number of diffuser vanes was carried out at design point. Finally, an optimized centrifugal compressor stage fulfilled the high expectations and presented proper performance. Numerical simulation showed that at design point the stage adiabatic efficiency was 79.93% and the total pressure ratio was 5.6. The surge margin was 15%. The performance map including 80%, 90% and 100% design speed was also presented.
Tokamak with in situ magnetohydrodynamic generation of toroidal magnetic field
Schaffer, Michael J.
1986-01-01
A tokamak apparatus includes an electrically conductive metal pressure vessel for defining a chamber and confining liquid therein. A liner disposed within said chamber defines a toroidal space within the liner and confines gas therein. The metal vessel provides an electrically conductive path linking the toroidal space. Liquid metal is forced outwardly through the chamber outside of the toroidal space to generate electric current in the conductive path and thereby generate a toroidal magnetic field within the toroidal space. Toroidal plasma is developed within the toroidal space about the major axis thereof.
LASL toroidal reversed-field pinch programme
International Nuclear Information System (INIS)
The determination of the absolute energy loss due to radiation from impurities in the LASL toroidal reversed-field pinch experiment ZT-S is reported. The measurements show that over half the energy loss is accounted for by this mechanism. Thomson-scattering electron density measurements indicate only a gradual increase in temperature as the filling pressure is reduced, indicating an increased energy loss at lower pressures. Cylindrical and toroidal simulations of the experiment indicate either that a highly radiative pinch boundary or anomalous transport is needed to match the experimental results. New effects on the equilibrium due to plasma flows induced by the toroidal geometry are predicted by the toroidal simulations. The preliminary results on the low-temperature discharge cleaning of the ZT-S torus are reported. A description of the upgrade of the ZT-S experiment and the objectives, construction and theoretical predictions for the new ZT-40 experiment are given. (author)
Toroidal Horizons in Binary Black Hole Mergers
Bohn, Andy; Teukolsky, Saul A
2016-01-01
We find the first binary black hole event horizon with a toroidal topology. It had been predicted that generically the event horizons of merging black holes should briefly have a toroidal topology, but such a phase has never been seen prior to this work. In all previous binary black hole simulations, in the coordinate slicing used to evolve the black holes, the topology of the event horizon transitions directly from two spheres during the inspiral to a single sphere as the black holes merge. We present a coordinate transformation to a foliation of spacelike hypersurfaces that "cut a hole" through the event horizon surface, resulting in a toroidal event horizon. A torus could potentially provide a mechanism for violating topological censorship. However, these toroidal event horizons satisfy topological censorship by construction, because we can always trivially apply the inverse coordinate transformation to remove the topological feature.
Toroidal horizons in binary black hole mergers
Bohn, Andy; Kidder, Lawrence E.; Teukolsky, Saul A.
2016-09-01
We find the first binary black hole event horizon with a toroidal topology. It has been predicted that generically the event horizons of merging black holes should briefly have a toroidal topology. However, such a phase has never been seen in numerical simulations. Instead, in all previous simulations, the topology of the event horizon transitions directly from two spheres during the inspiral to a single sphere as the black holes merge. We find a coordinate transformation to a foliation of spacelike hypersurfaces that "cut a hole" through the event horizon surface, resulting in a toroidal event horizon, thus reconciling the numerical work with theoretical expectations. The demonstration requires extremely high numerical precision, which is made possible by a new event horizon code described in a companion paper. A torus could potentially provide a mechanism for violating topological censorship. However, these toroidal event horizons satisfy topological censorship by construction, because we can always trivially apply the inverse coordinate transformation to remove the topological feature.
OCLATOR (One Coil Low Aspect Toroidal Reactor)
International Nuclear Information System (INIS)
A new approach to construct a tokamak-type reactor(s) is presented. Basically the return conductors of toroidal field coils are eliminated and the toroidal field coil is replaced by one single large coil, around which there will be placed several tokamaks or other toroidal devices. The elimination of return conductors should, in addition to other advantages, improve the accessibility and maintainability of the tokamaks and offer a possible alternative to the search for special materials to withstand large neutron wall loading, as the frequency of changeover would be increased due to minimum downtime. It also makes it possible to have a low aspect ratio tokamak which should improve the β limit, so that a low toroidal magnetic field strength might be acceptable, meaning that the NbTi superconducting wire could be used. This system is named OCLATOR
Low-n shear Alfven spectra in axisymmetric toroidal plasmas
International Nuclear Information System (INIS)
In toroidal plasmas, the toroidal magnetic field is nonuniform over a magnetic surface and causes coupling of different poloidal harmonics. It is shown both analytically and numerically that the toroidicity not only breaks up the shear Alfven continuous spectrum, but also creates new, discrete, toroidicity-induced shear Alfven eigenmodes with frequencies inside the continuum gaps. Potential applications of the low-n toroidicity-induced shear Alfven eigenmodes on plasma heating and instabilities are addressed. 17 refs., 4 figs
Anomalous transport in toroidal plasmas
International Nuclear Information System (INIS)
When the magnetic moment of particle is conserved, there are three mechanisms which cause anomalous transport. These are: variation of magnetic field strength in flux surface, variation of electrostatic potential in flux surface, and destruction of flux surface. The anomalous transport of different groups of particles resulting from each of these mechanisms is different. This fact can be exploited to determine the cause of transport operative in an experimental situation. This approach can give far more information on the transport than the standard confinement time measurements. To implement this approach, we have developed Monte Carlo codes for toroidal geometries. The equations of motion are developed in a set of non-canonical, practical Boozer co-ordinates by means of Jacobian transformations of the particle drift Hamiltonian equations of motion. Effects of collisions are included by appropriate stochastic changes in the constants of motion. Effects of the loop voltage on particle motions are also included. We plan to apply our method to study two problems: the problem of the hot electron tail observed in edge region of ZT-40, and the energy confinement time in TOKAPOLE II. For the ZT-40 problem three situations will be considered: a single mode in the core, a stochastic region that covers half the minor radius, a stochastic region that covers the entire plasma. A turbulent spectrum of perturbations based on the experimental data of TOKAPOLE II will be developed. This will be used to simulate electron transport resulting from ideal instabilities and resistive instabilities in TOKAPOLE II
Celebrating the Barrel Toroid commissioning
Peter Jenni
ATLAS invited Funding Agency representatives and Laboratory Heads directly related to the funding and construction of the Barrel Toroid for a small ceremony on 13th December 2006 at Point 1, in order to mark the successful first full excitation of the BT (see last eNews). On that date, which was during the December CERN Council week, several of the Funding Agency Heads or their representatives could be present, representing CEA France, INFN Italy, BMBF Germany, Spain, Sweden, Switzerland, Russia, JINR Dubna and CERN. Speeches were delivered by the ATLAS spokesperson Peter Jenni thanking the Funding Partners in the name of the Collaboration, by Magnet Project Leader Herman ten Kate tracing the BT construction history, and by the CERN Director-General Robert Aymar congratulating all those who have contributed to the successful project. Herman ten Kate addressing the delegates. The text of the introductory address by Peter Jenni is reproduced here. "It is a great pleasure for me to welcome you all here...
Plasma Spraying Reclaims Compressor Housings
Leissler, George W.; Yuhas, John S.
1991-01-01
Plasma-spraying process used to build up material in worn and pitted areas. Newly applied material remachined to specified surface contours. Effective technique for addition of metal to out-of-tolerance magnesium-alloy turbine-engine compressor housings.
Meridional Considerations of the Centrifugal Compressor Development
Directory of Open Access Journals (Sweden)
C. Xu
2012-01-01
Full Text Available Centrifugal compressor developments are interested in using optimization procedures that enable compressor high efficiency and wide operating ranges. Recently, high pressure ratio and efficiency of the centrifugal compressors require impeller design to pay attention to both the blade angle distribution and the meridional profile. The geometry of the blades and the meridional profile are very important contributions of compressor performance and structure reliability. This paper presents some recent studies of meridional impacts of the compressor. Studies indicated that the meridional profiles of the impeller impact the overall compressor efficiency and pressure ratio at the same rotational speed. Proper meridional profiles can improve the compressor efficiency and increase the overall pressure ratio at the same blade back curvature.
Pulse compressor with aberration correction
Energy Technology Data Exchange (ETDEWEB)
Mankos, Marian [Electron Optica, Inc., Palo Alto, CA (United States)
2015-11-30
In this SBIR project, Electron Optica, Inc. (EOI) is developing an electron mirror-based pulse compressor attachment to new and retrofitted dynamic transmission electron microscopes (DTEMs) and ultrafast electron diffraction (UED) cameras for improving the temporal resolution of these instruments from the characteristic range of a few picoseconds to a few nanoseconds and beyond, into the sub-100 femtosecond range. The improvement will enable electron microscopes and diffraction cameras to better resolve the dynamics of reactions in the areas of solid state physics, chemistry, and biology. EOI’s pulse compressor technology utilizes the combination of electron mirror optics and a magnetic beam separator to compress the electron pulse. The design exploits the symmetry inherent in reversing the electron trajectory in the mirror in order to compress the temporally broadened beam. This system also simultaneously corrects the chromatic and spherical aberration of the objective lens for improved spatial resolution. This correction will be found valuable as the source size is reduced with laser-triggered point source emitters. With such emitters, it might be possible to significantly reduce the illuminated area and carry out ultrafast diffraction experiments from small regions of the sample, e.g. from individual grains or nanoparticles. During phase I, EOI drafted a set of candidate pulse compressor architectures and evaluated the trade-offs between temporal resolution and electron bunch size to achieve the optimum design for two particular applications with market potential: increasing the temporal and spatial resolution of UEDs, and increasing the temporal and spatial resolution of DTEMs. Specialized software packages that have been developed by MEBS, Ltd. were used to calculate the electron optical properties of the key pulse compressor components: namely, the magnetic prism, the electron mirror, and the electron lenses. In the final step, these results were folded
Cummins/Tacom advanced adiabatic engine
Energy Technology Data Exchange (ETDEWEB)
Kamo, R.; Bryzik, W.
1984-01-01
Cummins Engine Company, Inc. and the U.S. Army have been jointly developing an adiabatic turbocompound engine during the last nine years. Although progress in the early years was slow, recent developments in the field of advanced ceramics have made it possible to make steady progress. It is now possible to reconsider the temperature limitation imposed on current heat engines and its subsequent influence on higher engine efficiency when using an exhaust energy utilization system. This paper presents an adiabatic turbocompound diesel engine concept in which high-performance ceramics are used in its design. The adiabatic turbocompound engine will enable higher operating temperatures, reduced heat loss, and higher exhaust energy recovery, resulting in higher thermal engine efficiency. This paper indicates that the careful selection of ceramics in engine design is essential. Adiabatic engine materials requirements are defined and the possible ceramic materials which will satisfy these requirements are identified. Examples in design considerations of engine components are illustrated. In addition to these important points, the use of ceramic coatings in the design of engine components. The first generation adiabatic engine with ceramic coatings is described. The advanced adiabatic engine with minimum friction features utilizaing ceramics is also presented. The advanced ceramic turbocharger turbine rotor as well as the oilless ceramic bearing design is described. Finally, the current status of the advanced adiabatic engine program culminating in the AA750 V-8 adiabatic engine is presented.
Shortcut to adiabatic gate teleportation
Santos, Alan C.; Silva, Raphael D.; Sarandy, Marcelo S.
2016-01-01
We introduce a shortcut to the adiabatic gate teleportation model of quantum computation. More specifically, we determine fast local counterdiabatic Hamiltonians able to implement teleportation as a universal computational primitive. In this scenario, we provide the counterdiabatic driving for arbitrary n -qubit gates, which allows to achieve universality through a variety of gate sets. Remarkably, our approach maps the superadiabatic Hamiltonian HSA for an arbitrary n -qubit gate teleportation into the implementation of a rotated superadiabatic dynamics of an n -qubit state teleportation. This result is rather general, with the speed of the evolution only dictated by the quantum speed limit. In particular, we analyze the energetic cost for different Hamiltonian interpolations in the context of the energy-time complementarity.
Adiabatic quantum optimization with qudits
Amin, M H S; Smith, Peter
2011-01-01
Most realistic solid state devices considered as qubits are not true two-state systems but multi-level systems. They can approximately be considered as qubits only if the energy separation of the upper energy levels from the lowest two is very large. If this condition is not met, the upper states may affect the evolution and therefore cannot be neglected. Here, we consider devices with double-well potential as basic logical elements, and study the effect of higher energy levels, beyond the lowest two, on adiabatic quantum optimization. We show that the extra levels can be modeled by adding additional (ancilla) qubits coupled to the original (logical) qubits. The presence of these levels is shown to have no effect on the final ground state. We also study their influence on the minimum gap for a set of 8-qubit spin glass instances.
On a Nonlinear Model in Adiabatic Evolutions
Sun, Jie; Lu, Song-Feng
2016-08-01
In this paper, we study a kind of nonlinear model of adiabatic evolution in quantum search problem. As will be seen here, for this problem, there always exists a possibility that this nonlinear model can successfully solve the problem, while the linear model can not. Also in the same setting, when the overlap between the initial state and the final stare is sufficiently large, a simple linear adiabatic evolution can achieve O(1) time efficiency, but infinite time complexity for the nonlinear model of adiabatic evolution is needed. This tells us, it is not always a wise choice to use nonlinear interpolations in adiabatic algorithms. Sometimes, simple linear adiabatic evolutions may be sufficient for using. Supported by the National Natural Science Foundation of China under Grant Nos. 61402188 and 61173050. The first author also gratefully acknowledges the support from the China Postdoctoral Science Foundation under Grant No. 2014M552041
The thermal-flow behavior of the working chamber in an oil-free scroll compressor
Rak, Józef
2013-09-01
The paper presents the full transient, two-dimensional finite volume method numerical calculations of the classical involute scroll compressor geometry. The purpose of the study was to develop and evaluate an adaptable implementation of numerical fluid mechanics and thermodynamics modeling procedure with a mesh deformation. The methodology consisting in the compression chamber geometry preparation, mesh generation and governing equations solving was described. The evaluation was carried by simulating an adiabatic compression process and the results were compared with the theoretical zero-dimensional model and the existing research concerning the scroll chamber computational fluid dynamics modeling. It has been shown that the proposed modeling routine results in good accuracy for the scroll compressors study applications.
Blade Parameterization and Aerodynamic Design Optimization for a 3D Transonic Compressor Rotor
Institute of Scientific and Technical Information of China (English)
Naixing Chen; Hongwu Zhang; Yanji Xu; Weiguang Huang
2007-01-01
The present paper describes an optimization methodology for aerodynamic design of turbomachinery combined with a rapid 3D blade and grid generator (RAPID3DGRID), a N.S. solver, a blade parameterization method (BPM), a gradient-based parameterization-analyzing method (GPAM), a response surface method (RSM) with zooming algorithm and a simple gradient method. By the use of blade parameterization method a transonic compressor rotor can be expressed by a set of polynomials, and then it enables us to transform coordinate-expressed blade data to parameter-expressed and then to reduce the number of parameters. With changing any one of the parameters and by applying grid generator and N.S. solver, we can obtain several groups of samples. Here only ten parameters were considered to search an optimized compressor rotor. As a result of optimization, the adiabatic efficiency was increased by 1.73%.
Optical force on toroidal nanostructures: toroidal dipole versus renormalized electric dipole
Zhang, Xu-Lin; Lin, Zhifang; Sun, Hong-Bo; Chan, C T
2015-01-01
We study the optical forces acting on toroidal nanostructures. A great enhancement of optical force is unambiguously identified as originating from the toroidal dipole resonance based on the source-representation, where the distribution of the induced charges and currents is characterized by the three families of electric, magnetic, and toroidal multipoles. On the other hand, the resonant optical force can also be completely attributed to an electric dipole resonance in the alternative field-representation, where the electromagnetic fields in the source-free region are expressed by two sets of electric and magnetic multipole fields based on symmetry. The confusion is resolved by conceptually introducing the irreducible electric dipole, toroidal dipole, and renormalized electric dipole. We demonstrate that the optical force is a powerful tool to identify toroidal response even when its scattering intensity is dwarfed by the conventional electric and magnetic multipoles.
Beede, William L.; Kottas, Harry
1948-01-01
The production-model 333-A-23 turbojet-engine compressor with a 17-blade impeller was operated at ambient and 0 F inlet temperatures and at inlet pressures of 14 and 5 inches mercury absolute for equivalent impeller speeds from 6000 to 12,750 rpm. The results of this investigation are compared with those of the 533-A-21 compressor. At the design equivalent speed of 11,750 rpm the maximum pressure ratio was 4.39. This occurred at the surge point at which the equivalent weight flow was 80.8 pounds per second, ana the adiabatic temperature-rise efficiency was 0.757. The maximum flow at the design equivalent speed was 88.0 pounds per second. The maximum adiabatic temperature-rise efficiency of 0.799 was obtained at an equivalent speed of 10,000 rpm, and equivalent weight flow of 62.9 pounds per second, and a pressure ratio of 3.20. At the maximum equivalent speed investigated (12,750 rpm), a peak pressure ratio of 4.90 was attained at an equivalent weight flow of 85.4 pounds per second and an efficiency of 0.680.
Partial evolution based local adiabatic quantum search
Institute of Scientific and Technical Information of China (English)
Sun Jie; Lu Song-Feng; Liu Fang; Yang Li-Ping
2012-01-01
Recently,Zhang and Lu provided a quantum search algorithm based on partial adiabatic evolution,which beats the time bound of local adiabatic search when the number of marked items in the unsorted database is larger than one.Later,they found that the above two adiabatic search algorithms had the same time complexity when there is only one marked item in the database.In the present paper,following the idea of Roland and Cerf [Roland J and Cerf N J 2002Phys.Rev.A 65 042308],if within the small symmetric evolution interval defined by Zhang et al.,a local adiabatic evolution is performed instead of the original “global” one,this “new” algorithm exhibits slightly better performance,although they are progressively equivalent with M increasing.In addition,the proof of the optimality for this partial evolution based local adiabatic search when M =1 is also presented.Two other special cases of the adiabatic algorithm obtained by appropriately tuning the evolution interval of partial adiabatic evolution based quantum search,which are found to have the same phenomenon above,are also discussed.
ORNL Levitated Toroidal Multipole Program
International Nuclear Information System (INIS)
We are studying confinement of gun-injected and microwave-produced plasmas in a levitated toroidal quadrupole in which internal hoop supports are not present to limit plasma confinement. Electromagnetic levitation is made possible by reducing the 60 Hz skin depth in the copper walls with liquid nitrogen cooling. The cooling also increases the magnetic field lifetime so that an e-folding time of 17 ms was measured after crowbarring. Computations indicate that in a properly designed, larger device, an e-folding time of 100 ms can be reached. Washer-gun hydrogen plasmas and Bostick-type lithium gun plasmas were injected into the levitated quadrupole with typical parameters: B ≥ 3 kG, Te ≈ 3 eV, ni ≈ 109 cm-3, and 1 i i ≈ 1010 cm-3, Te ≈ 30 eV, and τ/τBohm ≈ 30. Density fluctuations (Δn/n) in the region of good field curvature were less than 0.05 and in the region of bad curvature 0.10-0.25. With the removal of the magnetic well (by removing the inner hoop), τ/τBohm and ni each dropped a factor of 4 and Δn/n became greater than 0.25. Recent experiments using 200 W at λ = 3 cm have produced plasmas with higher densities (n > 1011 cm-3 assuming Te ≈ 100 eV), higher temperatures (Te ≈ 100 eV) and longer lifetimes (τ ≈ 80 μs ≈ 40 τBohm) than in the λ = 12 cm experiments. Detailed probe measurements of density and temperature are consistent with models for plasma behaviour based on computed magnetic field plots. Probe data show clear evidence of the changes in heating zones during the variation of the sinusoidal magnetic field and a large obstacle intercepting all flux lines effectively prevents the formation of the plasma. We are also studying a levitated helical hexapole, whose advantages over the quadrupole are a better ratio of connection length to radius of bad curvature and more confinement volume. (author)
Digital Waveguide Adiabatic Passage Part 2: Experiment
Ng, Vincent; Chaboyer, Zachary J; Nguyen, Thach; Dawes, Judith M; Withford, Michael J; Greentree, Andrew D; Steel, M J
2016-01-01
Using a femtosecond laser writing technique, we fabricate and characterise three-waveguide digital adiabatic passage devices, with the central waveguide digitised into five discrete waveguidelets. Strongly asymmetric behaviour was observed, devices operated with high fidelity in the counter-intuitive scheme while strongly suppressing transmission in the intuitive. The low differential loss of the digital adiabatic passage designs potentially offers additional functionality for adiabatic passage based devices. These devices operate with a high contrast ($>\\!90\\%$) over a 60~nm bandwidth, centered at $\\sim 823$~nm.
Diffusion models for Knudsen compressors
Aoki, Kazuo; Degond, Pierre; Takata, Shigeru; Yoshida, Hiroaki
2007-01-01
A rarefied gas in a long straight pipe with a periodic structure consisting of alternately arranged narrow and wide pipes and with periodic temperature distribution, which is known as the Knudsen compressor (or pump), is considered. Under the assumption that the pipe is much thinner than the period, a diffusion model that describes the pressure distribution and mass flux of the gas in each pipe element is derived, together with the connection conditions at the junctions of the narrow and wide...
Modelling fluid flow in a reciprocating compressor
Tuhovcak, Jan; Hejčík, Jiří; Jícha, Miroslav
2015-05-01
Efficiency of reciprocating compressor is strongly dependent on the valves characteristics, which affects the flow through the suction and discharge line. Understanding the phenomenon inside the compressor is necessary step in development process. Commercial CFD tools offer wide capabilities to simulate the flow inside the reciprocating compressor, however they are too complicated in terms of computational time and mesh creation. Several parameters describing compressor could be therefore examined without the CFD analysis, such is valve characteristic, flow through the cycle and heat transfer. The aim of this paper is to show a numerical tool for reciprocating compressor based on the energy balance through the cycle, which provides valve characteristics, flow through the cycle and heat losses from the cylinder. Spring-damping-mass model was used for the valve description. Boundary conditions were extracted from the performance test of 4-cylinder semihermetic compressor and numerical tool validation was performed with indicated p-V diagram comparison.
Modelling fluid flow in a reciprocating compressor
Directory of Open Access Journals (Sweden)
Tuhovcak Jan
2015-01-01
Full Text Available Efficiency of reciprocating compressor is strongly dependent on the valves characteristics, which affects the flow through the suction and discharge line. Understanding the phenomenon inside the compressor is necessary step in development process. Commercial CFD tools offer wide capabilities to simulate the flow inside the reciprocating compressor, however they are too complicated in terms of computational time and mesh creation. Several parameters describing compressor could be therefore examined without the CFD analysis, such is valve characteristic, flow through the cycle and heat transfer. The aim of this paper is to show a numerical tool for reciprocating compressor based on the energy balance through the cycle, which provides valve characteristics, flow through the cycle and heat losses from the cylinder. Spring-damping-mass model was used for the valve description. Boundary conditions were extracted from the performance test of 4-cylinder semihermetic compressor and numerical tool validation was performed with indicated p-V diagram comparison.
Linear Motor Free Piston Compressor
Bloomfield, David P.
1995-02-01
A Linear Motor Free Piston Compressor (LMFPC), a free piston pressure recovery system for fuel cell powerplants was developed. The LMFPC consists of a reciprocating compressor and a reciprocating expander which are separated by a piston. In the past energy efficient turbochargers have been used for pressure large (over 50 kW) fuel cell powerplants by recovering pressure energy from the powerplant exhaust. A free piston compressor allows pressurizing 3 - 5 kW sized fuel cell powerplants. The motivation for pressurizing PEM fuel cell powerplants is to improve fuel cell performance. Pressurization of direct methanol fuel cells will be required if PEM membranes are to be used Direct methanol oxidation anode catalysts require high temperatures to operate at reasonable power densities. The elevated temperatures above 80 C will cause high water loss from conventional PEM membranes unless pressurization is employed. Because pressurization is an energy intensive process, recovery of the pressure energy is required to permit high efficiency in fuel cell powerplants. A complete LMFPC which can pressurize a 3 kW fuel cell stack was built. This unit is one of several that were constructed during the course of the program.
Numerical simulation of radial compressor stage
Luňáček O.; Syka T.
2013-01-01
Article describes numerical simulations of air flow in radial compressor stage in NUMECA CFD software. In simulations geometry variants with and without seals are used. During tasks evaluating was observed seals influence on flow field and performance parameters of compressor stage. Also is described CFDresults comparison with results from design software based on experimental measurements and monitoring of influence of seals construction on compressor stage efficiency.
Rotary Compressor With The Stationary Crankshaft
Dreiman, Nelik
2014-01-01
A parts of the contemporary rotary compressors are supported as by revolving crankshaft (rotor, roller, etc.), so by the housing (stator, pump, suction accumulator, etc.). Such dual supporting structure complicates assembly of a compressor due to the necessity of precision axial and radial positioning of the pump parts, motor rotor and stator. Developed novel rotary compressor provides a unitary assembly, in which a rotor of the driver -external rotor electric motor, is integrated with concen...
A Classification Scheme For Toroidal Molecules
Berger, J; Berger, Jorge; Avron, Joseph E.
1995-01-01
We construct a class of periodic tilings of the plane, which corresponds to toroidal arrangements of trivalent atoms, with pentagonal, hexagonal and heptagonal rings. Each tiling is characterized by a set of four integers and determines a toroidal molecule. The tiling rules are motivated by geometric considerations and the tiling patterns are rich enough to describe a wide class of toroidal carbon molecules, with a broad range of shapes and numbers of atoms. The molecular dimensions are simply related to the integers that determine the tiling. The configurational energy and the delocalisation energy of several molecules obtained in this way were computed for Tersoff and H\\"uckel models. The results indicate that many of these molecules are not strained, and may be expected to be stable. We studied the influence of size on the H\\"{u}ckel spectrum: it bears both similarities and differences as compared with the case of tubules.
Ferroic nature of magnetic toroidal order.
Zimmermann, Anne S; Meier, Dennis; Fiebig, Manfred
2014-09-05
Electric dipoles and ferroelectricity violate spatial inversion symmetry, and magnetic dipoles and ferromagnetism break time-inversion symmetry. Breaking both symmetries favours magnetoelectric charge-spin coupling effects of enormous interest, such as multiferroics, skyrmions, polar superconductors, topological insulators or dynamic phenomena such as electromagnons. Extending the rationale, a novel type of ferroic order violating space- and time-inversion symmetry with a single order parameter should exist. This existence is fundamental and the inherent magnetoelectric coupling is technologically interesting. A uniform alignment of magnetic vortices, called ferrotoroidicity, was proposed to represent this state. Here we demonstrate that the magnetic vortex pattern identified in LiCoPO4 exhibits the indispensable hallmark of such a ferroic state, namely hysteretic poling of ferrotoroidic domains in the conjugate toroidal field, along with a distinction of toroidal from non-toroidal poling effects. This consolidates ferrotoroidicity as fourth form of ferroic order.
Packing of charged chains on toroidal geometries
Yao, Zhenwei; de la Cruz, Monica Olvera
2013-01-01
We study a strongly adsorbed flexible polyelectrolyte chain on tori. In this generalized Thomson problem, the patterns of the adsorbed chain are analyzed in the space of the toroidal coordinates and in terms of the orientation of each chain segment. Various patterns are found, including double spirals, disclination-like structures, Janus tori, and uniform wrappings, arising from the long-range electrostatic interaction and the toroidal geometry. Their broken mirror symmetry is quantitatively characterized by introducing an order parameter, an integral of the torsion. The uniform packing, which breaks the mirror symmetry the least, has the lowest value of the order parameter. In addition, it is found that the electrostatic energy of confined chains on tori conforms to a power law regardless of the screening effect in some typical cases studied. Furthermore, we study random walks on tori that generate chain configurations in the large screening limit or at large thermal fluctuation; some features associated with the toroidal geometry are discussed.
Thermoelectric Effects under Adiabatic Conditions
Directory of Open Access Journals (Sweden)
George Levy
2013-10-01
Full Text Available This paper investigates not fully explained voltage offsets observed by several researchers during the measurement of the Seebeck coefficient of high Z materials. These offsets, traditionally attributed to faulty laboratory procedures, have proven to have an irreducible component that cannot be fully eliminated in spite of careful laboratory procedures. In fact, these offsets are commonly observed and routinely subtracted out of commercially available Seebeck measurement systems. This paper offers a possible explanation based on the spontaneous formation of an adiabatic temperature gradient in the presence of a force field. The diffusion-diffusion heat transport mechanism is formulated and applied to predict two new thermoelectric effects. The first is the existence of a temperature gradient across a potential barrier in a semiconductor and the second is the Onsager reciprocal of the first, that is, the presence of a measureable voltage that arises across a junction when the temperature gradient is forced to zero by a thermal clamp. Suggested future research includes strategies for utilizing the new thermoelectric effects.
Research on Metal Hydride Compressor System
Institute of Scientific and Technical Information of China (English)
无
1999-01-01
Ti-Zr series Laves phase hydrogen storage alloys with good hydrogen storage properties, such as large hydrogen capacity, rapid hydriding and dehydriding rate, high compression ratio, gentle plateau, small hysteresis, easily being activated and long cyclic stability etc. for metal hydride compressor have been investigated. In addition, a hydride compressor with special characteristics, namely, advanced filling method, good heat transfer effect and reasonable structural design etc. has also been constructed. A hydride compressor cryogenic system has been assembled coupling the compressor with a J-T micro-throttling refrigeration device and its cooling capacity can reach 0.4 W at 25 K.
Aspirated Compressors for High Altitude Engines Project
National Aeronautics and Space Administration — Aurora Flight Sciences proposes to incorporate aspirated compressor technology into a high altitude, long endurance (HALE) concept engine. Aspiration has been...
Anomalous transport equations in toroidal plasmas
International Nuclear Information System (INIS)
Reduced transport equations for a toroidal plasma with fluctuations are derived. These equations include the effects of both anomalous and standard neoclassical transport, and allow clarification of the structure of convective fluxes caused by electrostatic and magnetic fluctuations. Special attention is paid to the combined effects of fluctuations and toroidicity on the transport. The formulation retains the effects of a magnetic field inhomogeneity on the anomalous transport. It is shown that phase space diffusion caused by the gradient in the equilibrium magnetic field appears as a pinch flux in the real space
Models for large superconducting toroidal magnet systems
International Nuclear Information System (INIS)
Prior to the design of large GJ toroidal magnet systems it is appropriate to procure small scale models, which can simulate their pertinent properties and allow to investigate their relevant phenomena. The important feature of the model is to show under which circumstances the system performance can be extrapolated to large magnets. Based on parameters such as the maximum magnetic field and the current density, the maximum tolerable magneto-mechanical stresses, a simple method of designing model magnets is presented. It is shown how pertinent design parameters are changed when the toroidal dimensions are altered. In addition some conductor cost estimations are given based on reactor power output and wall loading
Toroidal Horizons in Binary Black Hole Mergers
Bohn, Andy; Kidder, Lawrence E.; Teukolsky, Saul A.
2016-01-01
We find the first binary black hole event horizon with a toroidal topology. It had been predicted that generically the event horizons of merging black holes should briefly have a toroidal topology, but such a phase has never been seen prior to this work. In all previous binary black hole simulations, in the coordinate slicing used to evolve the black holes, the topology of the event horizon transitions directly from two spheres during the inspiral to a single sphere as the black holes merge. ...
Toroidal Precession as a Geometric Phase
Energy Technology Data Exchange (ETDEWEB)
J.W. Burby and H. Qin
2012-09-26
Toroidal precession is commonly understood as the orbit-averaged toroidal drift of guiding centers in axisymmetric and quasisymmetric configurations. We give a new, more natural description of precession as a geometric phase effect. In particular, we show that the precession angle arises as the holonomy of a guiding center's poloidal trajectory relative to a principal connection. The fact that this description is physically appropriate is borne out with new, manifestly coordinate-independent expressions for the precession angle that apply to all types of orbits in tokamaks and quasisymmetric stellarators alike. We then describe how these expressions may be fruitfully employed in numerical calculations of precession.
Some properties of toroidal isodynamic magnetostatic equilibria
Energy Technology Data Exchange (ETDEWEB)
Aly, J.-J. [AIM, Unite Mixte de Recherche CEA, CNRS, Universite Paris VII, UMR no 7158, Centre d' Etudes de Saclay, F-91191 Gif sur Yvette Cedex (France)
2011-09-15
We establish some general properties of a 3D isodynamic magnetostatic equilibrium admitting a family of nested toroidal flux surfaces. In particular, we use the virial theorem to prove a simple relation between the total pressure (magnetic + thermal) and the magnetic pressure on each flux surface, and we derive some useful consequences of the latter. We also show the constancy on each rational surface of two integrals along magnetic lines. As a simple application of our results, we show the nonexistence of an equilibrium with vanishing toroidal current, and of an equilibrium with closed lines.
Adiabatic hydrodynamics: The eightfold way to dissipation
Haehl, Felix M; Rangamani, Mukund
2015-01-01
We provide a complete solution to hydrodynamic transport at all orders in the gradient expansion compatible with the second law constraint. The key new ingredient we introduce is the notion of adiabaticity, which allows us to take hydrodynamics off-shell. Adiabatic fluids are such that off-shell dynamics of the fluid compensates for entropy production. The space of adiabatic fluids is quite rich, and admits a decomposition into seven distinct classes. Together with the dissipative class this establishes the eightfold way of hydrodynamic transport. Furthermore, recent results guarantee that dissipative terms beyond leading order in the gradient expansion are agnostic of the second law. While this completes a transport taxonomy, we go on to argue for a new symmetry principle, an Abelian gauge invariance that guarantees adiabaticity in hydrodynamics. We suggest that this symmetry is the macroscopic manifestation of the microscopic KMS invariance. We demonstrate its utility by explicitly constructing effective ac...
Adiabatic Invariance of Oscillons/I-balls
Kawasaki, Masahiro; Takeda, Naoyuki
2015-01-01
Real scalar fields are known to fragment into spatially localized and long-lived solitons called oscillons or $I$-balls. We prove the adiabatic invariance of the oscillons/$I$-balls for a potential that allows periodic motion even in the presence of non-negligible spatial gradient energy. We show that such potential is uniquely determined to be the quadratic one with a logarithmic correction, for which the oscillons/$I$-balls are absolutely stable. For slightly different forms of the scalar potential dominated by the quadratic one, the oscillons/$I$-balls are only quasi-stable, because the adiabatic charge is only approximately conserved. We check the conservation of the adiabatic charge of the $I$-balls in numerical simulation by slowly varying the coefficient of logarithmic corrections. This unambiguously shows that the longevity of oscillons/$I$-balls is due to the adiabatic invariance.
Adiabatic Quantum Search in Open Systems
Wild, Dominik S.; Gopalakrishnan, Sarang; Knap, Michael; Yao, Norman Y.; Lukin, Mikhail D.
2016-10-01
Adiabatic quantum algorithms represent a promising approach to universal quantum computation. In isolated systems, a key limitation to such algorithms is the presence of avoided level crossings, where gaps become extremely small. In open quantum systems, the fundamental robustness of adiabatic algorithms remains unresolved. Here, we study the dynamics near an avoided level crossing associated with the adiabatic quantum search algorithm, when the system is coupled to a generic environment. At zero temperature, we find that the algorithm remains scalable provided the noise spectral density of the environment decays sufficiently fast at low frequencies. By contrast, higher order scattering processes render the algorithm inefficient at any finite temperature regardless of the spectral density, implying that no quantum speedup can be achieved. Extensions and implications for other adiabatic quantum algorithms will be discussed.
Twenty Years of Compressor Innovation at NTU, Singapore
Ooi, Kim Tiow
2014-01-01
In this paper, innovations in refrigeration compressors and their mechanisms which were conceptualised (and some of these were commercialised) at Nanyang Technological University in Singapore over the past twenty years are discussed and presented. These innovations include piezo compressor [1-3], sliding cam compressor [4], rotaprocating compressor [5], revolving vane compressor and its variants [6-14], revolving vane expander [15] and cross-vane mechanism for expander-compressor unit [16]. T...
The effect of sheared toroidal rotation on pressure driven magnetic islands in toroidal plasmas
Hegna, C. C.
2016-05-01
The impact of sheared toroidal rotation on the evolution of pressure driven magnetic islands in tokamak plasmas is investigated using a resistive magnetohydrodynamics model augmented by a neoclassical Ohm's law. Particular attention is paid to the asymptotic matching data as the Mercier indices are altered in the presence of sheared flow. Analysis of the nonlinear island Grad-Shafranov equation shows that sheared flows tend to amplify the stabilizing pressure/curvature contribution to pressure driven islands in toroidal tokamaks relative to the island bootstrap current contribution. As such, sheared toroidal rotation tends to reduce saturated magnetic island widths.
Adiabatic Approximation, Semiclassical Scattering, and Unidirectional Invisibility
Mostafazadeh, Ali
2014-01-01
arXiv:1401.4315v3 [quant-ph] 27 Feb 2014 Adiabatic Approximation, Semiclassical Scattering, and Unidirectional Invisibility Ali Mostafazadeh∗ Department of Mathematics, Ko¸c University, 34450 Sarıyer, Istanbul, Turkey Abstract The transfer matrix of a possibly complex and energy-dependent scattering potential can be identified with the S-matrix of a two-level time-dependent non-Hermitian Hamiltonian H( ). We show that the application of the adiabatic approximation ...
Adiabatic description of nonspherical quantum dot models
Energy Technology Data Exchange (ETDEWEB)
Gusev, A. A., E-mail: gooseff@jinr.ru; Chuluunbaatar, O.; Vinitsky, S. I. [Joint Institute for Nuclear Research (Russian Federation); Dvoyan, K. G.; Kazaryan, E. M.; Sarkisyan, H. A. [Russian-Armenian (Slavonic) University (Armenia); Derbov, V. L.; Klombotskaya, A. S.; Serov, V. V. [Saratov State University (Russian Federation)
2012-10-15
Within the effective mass approximation an adiabatic description of spheroidal and dumbbell quantum dot models in the regime of strong dimensional quantization is presented using the expansion of the wave function in appropriate sets of single-parameter basis functions. The comparison is given and the peculiarities are considered for spectral and optical characteristics of the models with axially symmetric confining potentials depending on their geometric size, making use of the complete sets of exact and adiabatic quantum numbers in appropriate analytic approximations.
Adiabatic Connection for Strictly-Correlated Electrons
Liu, Zhenfei; Burke, Kieron
2009-01-01
Modern density functional theory (DFT) calculations employ the Kohn-Sham (KS) system of non-interacting electrons as a reference, with all complications buried in the exchange-correlation energy (Exc). The adiabatic connection formula gives an exact expression for Exc. We consider DFT calculations that instead employ a reference of strictly-correlated electrons. We define a "decorrelation energy" that relates this reference to the real system, and derive the corresponding adiabatic connection...
On adiabatic invariant in generalized Galileon theories
Ema, Yohei; Jinno, Ryusuke; Mukaida, Kyohei; Nakayama,Kazunori
2015-01-01
We consider background dynamics of generalized Galileon theories in the context of inflation, where gravity and inflaton are non-minimally coupled to each other. In the inflaton oscillation regime, the Hubble parameter and energy density oscillate violently in many cases, in contrast to the Einstein gravity with minimally coupled inflaton. However, we find that there is an adiabatic invariant in the inflaton oscillation regime in any generalized Galileon theory. This adiabatic invariant is us...
Electromagnetic toroidal excitations in matter and free space.
Papasimakis, N; Fedotov, V A; Savinov, V; Raybould, T A; Zheludev, N I
2016-03-01
The toroidal dipole is a localized electromagnetic excitation, distinct from the magnetic and electric dipoles. While the electric dipole can be understood as a pair of opposite charges and the magnetic dipole as a current loop, the toroidal dipole corresponds to currents flowing on the surface of a torus. Toroidal dipoles provide physically significant contributions to the basic characteristics of matter including absorption, dispersion and optical activity. Toroidal excitations also exist in free space as spatially and temporally localized electromagnetic pulses propagating at the speed of light and interacting with matter. We review recent experimental observations of resonant toroidal dipole excitations in metamaterials and the discovery of anapoles, non-radiating charge-current configurations involving toroidal dipoles. While certain fundamental and practical aspects of toroidal electrodynamics remain open for the moment, we envision that exploitation of toroidal excitations can have important implications for the fields of photonics, sensing, energy and information. PMID:26906961
Hierarchical theory of quantum adiabatic evolution
Zhang, Qi; Gong, Jiangbin; Wu, Biao
2014-12-01
Quantum adiabatic evolution is a dynamical evolution of a quantum system under slow external driving. According to the quantum adiabatic theorem, no transitions occur between nondegenerate instantaneous energy eigenstates in such a dynamical evolution. However, this is true only when the driving rate is infinitesimally small. For a small nonzero driving rate, there are generally small transition probabilities between the energy eigenstates. We develop a classical mechanics framework to address the small deviations from the quantum adiabatic theorem order by order. A hierarchy of Hamiltonians is constructed iteratively with the zeroth-order Hamiltonian being determined by the original system Hamiltonian. The kth-order deviations are governed by a kth-order Hamiltonian, which depends on the time derivatives of the adiabatic parameters up to the kth-order. Two simple examples, the Landau-Zener model and a spin-1/2 particle in a rotating magnetic field, are used to illustrate our hierarchical theory. Our analysis also exposes a deep, previously unknown connection between classical adiabatic theory and quantum adiabatic theory.
On the stabilization of toroidal pinches by finite larmor radius effects and toroidal magnetic field
International Nuclear Information System (INIS)
The radial eigenvalue problem for internal modes in a large aspect ratio toriodal pinch has been solved. A particularly stable regime for a weak but nonzero toroidal magnetic field has been found. (31 refs.)
ATLAS: Full power for the toroid magnet
2006-01-01
The 9th of November was a memorable day for ATLAS. Just before midnight, the gigantic Barrel toroid magnet reached its nominal field of 4 teslas in the coil windings, with an electrical current of 21000 amperes (21 kA) passing through the eight superconducting coils (as seen on the graph). This achievement was obtained after several weeks of commissioning. The ATLAS Barrel Toroid was first cooled down for about six weeks in July-August to -269Â°C (4.8 K) and then powered up step-by-step in successive test sessions to 21 kA. This is 0.5 kA above the current required to produce the nominal magnetic field. Afterwards, the current was safely switched off and the stored magnetic energy of 1.1 gigajoules was dissipated in the cold mass, raising its temperature to a safe -218Â°C (55 K). 'We can now say that the ATLAS Barrel Toroid is ready for physics,' said Herman ten Kate, project leader for the ATLAS magnet system. The ATLAS barrel toroid magnet is the result of a close collaboration between the magnet la...
Reduced Magnetohydrodynamic Equations in Toroidal Geometry
Institute of Scientific and Technical Information of China (English)
REN Shen-Ming; YU Guo-Yang
2001-01-01
By applying a new assumption of density, I.e. R2 p = const, the continuity equation is satisfied to the order ofe2`+with e being the inverse aspect ratio. In the case of large aspect ratio, a set of reduced magnetohydrodynamicequations in toroidal geometry are obtained. The new assumption about the density is supported by experimentalobservation to some extent.
Chiral Anomaly in Toroidal Carbon Nanotubes
Sasaki, K.
2001-01-01
It is pointed out that the chiral anomaly in 1+1 dimensions should be observed in toroidal carbon nanotubes on a planar geometry with varying magnetic field. We show that the chiral anomaly is closely connected with the persistent current in a one-dimensional metallic ring.
Celebration for the ATLAS Barrel Toroid magnet
2007-01-01
Representatives from Funding Agencies and Barrel Toroid Magnet Laboratories during the ceremony. From left to right: Jean Zinn-Justin (Head of DAPNIA/CEA/Saclay), CERN Director-General Robert Aymar, and Roberto Petronzio (President INFN).Allan Clark (DPNC University Geneva) and Enrique Fernandez (IFAE Barcelona) were among the guests visiting the ATLAS cavern. The barrel toroid is visible in the background. A celebration took place at Point 1 on 13 December to toast the recent powering-up of the ATLAS barrel toroid magnet to full field (Bulletin No. 47-48/06). About 70 guests were invited to attend, mainly composed of representatives from funding partners and key members of the laboratory management teams of the barrel toroid magnet, representing CEA France, INFN Italy, BMBF Germany, Spain, Sweden, Switzerland, Russia, JINR Dubna and CERN. An introductory speech by ATLAS spokesperson Peter Jenni the scene for evening. This was followed by the ATLAS magnet system project leader Herman Ten Kate's account of the...
ATLAS Barrel Toroid magnet reached nominal field
2006-01-01
Â OnÂ 9 November the barrel toroid magnet reached its nominal field of 4 teslas, with an electrical current of 21 000 amperes (21 kA) passing through the eight superconducting coils as shown on this graph
An Integrated Programming and Development Environment for Adiabatic Quantum Optimization
Humble, Travis S.; McCaskey, Alex J.; Bennink, Ryan S.; Billings, Jay J.; D'Azevedo, Ed F.; Sullivan, Blair D.; Klymko, Christine F.; Seddiqi, Hadayat
2013-01-01
Adiabatic quantum computing is a promising route to the computational power afforded by quantum information processing. The recent availability of adiabatic hardware has raised challenging questions about how to evaluate adiabatic quantum optimization programs. Processor behavior depends on multiple steps to synthesize an adiabatic quantum program, which are each highly tunable. We present an integrated programming and development environment for adiabatic quantum optimization called JADE tha...
High frequency dynamics in centrifugal compressors
Twerda, A.; Meulendijks, D.; Smeulers, J.P.M.; Handel, R. van den; Lier, L.J. van
2008-01-01
Problems with centrifugal compressors relating to high frequency, i.e. Blade passing frequency (BPF) are increasing. Pulsations and vibrations generated in centrifugal compressors can lead to nuisance, due to strong tonal noise, and even breakdown. In several cases the root cause of a failure or a n
Dynamical model for the toroidal sporadic meteors
Energy Technology Data Exchange (ETDEWEB)
Pokorný, Petr; Vokrouhlický, David [Institute of Astronomy, Charles University, V Holešovičkách 2, CZ-18000 Prague 8 (Czech Republic); Nesvorný, David [Department of Space Studies, Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302 (United States); Campbell-Brown, Margaret; Brown, Peter, E-mail: petr.pokorny@volny.cz, E-mail: vokrouhl@cesnet.cz, E-mail: davidn@boulder.swri.edu, E-mail: margaret.campbell@uwo.ca, E-mail: pbrown@uwo.ca [Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7 (Canada)
2014-07-01
More than a decade of radar operations by the Canadian Meteor Orbit Radar have allowed both young and moderately old streams to be distinguished from the dispersed sporadic background component. The latter has been categorized according to broad radiant regions visible to Earth-based observers into three broad classes: the helion and anti-helion source, the north and south apex sources, and the north and south toroidal sources (and a related arc structure). The first two are populated mainly by dust released from Jupiter-family comets and new comets. Proper modeling of the toroidal sources has not to date been accomplished. Here, we develop a steady-state model for the toroidal source of the sporadic meteoroid complex, compare our model with the available radar measurements, and investigate a contribution of dust particles from our model to the whole population of sporadic meteoroids. We find that the long-term stable part of the toroidal particles is mainly fed by dust released by Halley type (long period) comets (HTCs). Our synthetic model reproduces most of the observed features of the toroidal particles, including the most troublesome low-eccentricity component, which is due to a combination of two effects: particles' ability to decouple from Jupiter and circularize by the Poynting-Robertson effect, and large collision probability for orbits similar to that of the Earth. Our calibrated model also allows us to estimate the total mass of the HTC-released dust in space and check the flux necessary to maintain the cloud in a steady state.
Scroll Compressor Oil Pump Analysis
Branch, S.
2015-08-01
Scroll compressors utilize three journal bearings to absorb gas, friction and inertial loads exerted on the crankshaft. To function properly, these bearings must be lubricated with a certain amount of oil. The focus of this paper will be to discuss how computational fluid dynamics can be used to predict oil flow out of a single-stage oil pump. The effects of speed and lubricant viscosity on pump output will also be presented. The comparisons will look at mass flow rates, differences in pressure, and torque at various speeds and dynamic viscosities. The computational fluid dynamic analysis results will be compared with actual lab testing where a crankshaft bench tester was built.
Applications of numerical optimization techniques to design of axial compressor blades
Institute of Scientific and Technical Information of China (English)
Choon-Man Jang; Kwang-Yong Kim
2007-01-01
This paper describes the shape optimization of NASA rotor 37 and rotor and stator blades in a single-stage transonic axial compressor.Shape optimization of the blades operating at the design flow condition has been performed using the response surface method and three-dimensional Navier-Stokes analysis.Thin-layer approximation is introduced to the Navier-Stokes equations,and an explicit Runge-Kutta scheme is used to solve the governing equations.The three design variables,blade sweep,lean and skew,are introduced to optimize the three-dimensional stacking line of the blades.The objective function of the shape optimization is an adiabatic efficiency.Throughout the optimization of rotor and stator blades, optimal blade shape can be obtained.It is noted the increase of adiabatic efficiency by optimization of the blade shape with the stacking line in the single-stage transonic axial compressor is more effective in a rotor blade rather than a stator blade because of the large deformation of blade shape in the stator blade.
Assessment of total efficiency in adiabatic engines
Mitianiec, W.
2016-09-01
The paper presents influence of ceramic coating in all surfaces of the combustion chamber of SI four-stroke engine on working parameters mainly on heat balance and total efficiency. Three cases of engine were considered: standard without ceramic coating, fully adiabatic combustion chamber and engine with different thickness of ceramic coating. Consideration of adiabatic or semi-adiabatic engine was connected with mathematical modelling of heat transfer from the cylinder gas to the cooling medium. This model takes into account changeable convection coefficient based on the experimental formulas of Woschni, heat conductivity of multi-layer walls and also small effect of radiation in SI engines. The simulation model was elaborated with full heat transfer to the cooling medium and unsteady gas flow in the engine intake and exhaust systems. The computer program taking into account 0D model of engine processes in the cylinder and 1D model of gas flow was elaborated for determination of many basic engine thermodynamic parameters for Suzuki DR-Z400S 400 cc SI engine. The paper presents calculation results of influence of the ceramic coating thickness on indicated pressure, specific fuel consumption, cooling and exhaust heat losses. Next it were presented comparisons of effective power, heat losses in the cooling and exhaust systems, total efficiency in function of engine rotational speed and also comparison of temperature inside the cylinder for standard, semi-adiabatic and full adiabatic engine. On the basis of the achieved results it was found higher total efficiency of adiabatic engines at 2500 rpm from 27% for standard engine to 37% for full adiabatic engine.
Axial flow positive displacement worm compressor
Murrow, Kurt David (Inventor); Giffin, Rollin George (Inventor); Fakunle, Oladapo (Inventor)
2010-01-01
An axial flow positive displacement compressor has an inlet axially spaced apart and upstream from an outlet. Inner and outer bodies have offset inner and outer axes extend from the inlet to the outlet through first and second sections of a compressor assembly in serial downstream flow relationship. At least one of the bodies is rotatable about its axis. The inner and outer bodies have intermeshed inner and outer helical blades wound about the inner and outer axes respectively. The inner and outer helical blades extend radially outwardly and inwardly respectively. The helical blades have first and second twist slopes in the first and second sections respectively. The first twist slopes are less than the second twist slopes. An engine including the compressor has in downstream serial flow relationship from the compressor a combustor and a high pressure turbine drivingly connected to the compressor by a high pressure shaft.
Centrifugal compressor design for electrically assisted boost
Y Yang, M.; Martinez-Botas, R. F.; Zhuge, W. L.; Qureshi, U.; Richards, B.
2013-12-01
Electrically assisted boost is a prominent method to solve the issues of transient lag in turbocharger and remains an optimized operation condition for a compressor due to decoupling from turbine. Usually a centrifugal compressor for gasoline engine boosting is operated at high rotational speed which is beyond the ability of an electric motor in market. In this paper a centrifugal compressor with rotational speed as 120k RPM and pressure ratio as 2.0 is specially developed for electrically assisted boost. A centrifugal compressor including the impeller, vaneless diffuser and the volute is designed by meanline method followed by 3D detailed design. Then CFD method is employed to predict as well as analyse the performance of the design compressor. The results show that the pressure ratio and efficiency at design point is 2.07 and 78% specifically.
Refrigeration system having standing wave compressor
Lucas, Timothy S.
1992-01-01
A compression-evaporation refrigeration system, wherein gaseous compression of the refrigerant is provided by a standing wave compressor. The standing wave compressor is modified so as to provide a separate subcooling system for the refrigerant, so that efficiency losses due to flashing are reduced. Subcooling occurs when heat exchange is provided between the refrigerant and a heat pumping surface, which is exposed to the standing acoustic wave within the standing wave compressor. A variable capacity and variable discharge pressure for the standing wave compressor is provided. A control circuit simultaneously varies the capacity and discharge pressure in response to changing operating conditions, thereby maintaining the minimum discharge pressure needed for condensation to occur at any time. Thus, the power consumption of the standing wave compressor is reduced and system efficiency is improved.
Centrifugal compressor design for electrically assisted boost
International Nuclear Information System (INIS)
Electrically assisted boost is a prominent method to solve the issues of transient lag in turbocharger and remains an optimized operation condition for a compressor due to decoupling from turbine. Usually a centrifugal compressor for gasoline engine boosting is operated at high rotational speed which is beyond the ability of an electric motor in market. In this paper a centrifugal compressor with rotational speed as 120k RPM and pressure ratio as 2.0 is specially developed for electrically assisted boost. A centrifugal compressor including the impeller, vaneless diffuser and the volute is designed by meanline method followed by 3D detailed design. Then CFD method is employed to predict as well as analyse the performance of the design compressor. The results show that the pressure ratio and efficiency at design point is 2.07 and 78% specifically
On criterion of modal adiabaticity
Institute of Scientific and Technical Information of China (English)
WANG; Ning(
2001-01-01
［1］Pierce, A. D., Extension of the method of normal modes to sound propagation in an almost-stratified medium, J. Acoust.Soc. Am., 1965, 37: 19－27.［2］Wang, D. Z. , Shang, E. C., Underwater Acoustics (in Chinese), Beijing: Science Press, 1981.［3］Zhang Renhe, Li Fenghua, Beam-displacement rya-mode theory of sound propagation in shallow water, Science in China, Ser.A, 1999, 42(7): 739－749.［4］Zhou Jixun, Zhang Xuezhen, Rogers P., Resonance interaction of sound waves with internal solitons in coastal zone, J.Acoust. Soc. Am., 1991, 90: 2042－2054.［5］Shang, E. C., Wang, Y. Y., The impact of mesoscale oceanic structure on global-scale acoustic propagation, in Theoretical and Computational Acoustics (ed. Ding Lee et al. ), Singapore: World Scientific Publishing Co. , 1996, 409－431.［6］Milder, D. M., Ray and wave invariants for SOFAR channel propagation, J. Acoust. Soc. Am., 1969, 46: 1259－1263.［7］Nag l, A., Milder, D. M., Adiabatic mode theory of underwater sound propagation in a range-dependent environment, J.Acoust. Soc. Am., 1978, 63: 739－749.［8］Brekhovskikh, L. M., Waves in Layered Media, 2nd ed., New York: Academic Press Inc., 1973.［9］Brekhovskikh, L. M., Lysanov, Yu., Fundamental of Ocean Acoustics, Ch. 7, Sec. 7.2, Berlin: Springer-Verlag, 1982.［10］Evans, R. B., A coupled mode solution for acoustic propagation in a wave-guide with stepwise depth variations of a penerable bottom, J. Acoust. Soc. A.m., 1983, 74: 188－195.［11］Jensen, F. B., Kuperman, W. A., Porter, M. B. et al., Computational Ocean Acoustics, New York: Springer-Verlag,1992.［12］Wang Ning, Inverse scattering problem for the coupled second order ODE, Journal of The Physical Society of Japan, 1995, 64(12): 4907－4915.
Development of compact toroids injector for direct plasma controls
International Nuclear Information System (INIS)
The application of the compact toroids injector for direct plasma controls has been investigated. The compact toroids injection can fuel particles directly into the core of the plasma and modify the plasma profiles at the desired locations. The acceleration tests of the compact toroids have been conducted at Himeji Institute of Technology. The tests showed that the hydrogen compact toroid was accelerated up to 80km/s and the plasma density of the compact toroid was compressed to 1.2 x 1021m-3. (orig.)
Toroidal momentum transport in a tokamak caused by symmetry breaking parallel derivatives
Sung, Tobias; Casson, Francis; Fable, Emilino; Grosshauser, Stefan R; Hornsby, William; Migliano, Piereluigi; Peeters, Arthur G
2013-01-01
A new mechanism for toroidal momentum transport in a tokamak is investigated using the gyro-kinetic model. First, an analytic model is developed through the use of the ballooning transform. The terms that generate the momentum transport are then connected with the poloidal derivative of the ballooning envelope, which are one order smaller in the normalised Larmor radius, compared with the derivative of the eikonal. The mechanism, therefore, does not introduce an inhomogeneity in the radial direction, in contrast with the effect of profile shearing. Numerical simulations of the linear ion temperature gradient mode with adiabatic electrons, retaining the finite rho* effects in the ExB velocity, the drift, and the gyro-average, are presented. The momentum flux is found to be linear in the normalised Larmor radius (\\rho*) but is, nevertheless, generating a sizeable counter-current rotation. The total momentum flux scales linear with the aspect ratio of the considered magnetic surface, and increases with increasin...
Klein-Gordon equations for toroidal hydromagnetic waves in an axi-symmetric field
Directory of Open Access Journals (Sweden)
J. F. McKenzie
2010-03-01
Full Text Available In this paper we develop the hydromagnetic wave equations for toroidal Alfvén waves in a background axi-symmetric magnetic field. In the case where spatial variations are directed along the ambient magnetic field direction, the equations can be cast in a Klein-Gordon form in which the adiabatic-geometric amplitude factor of the perturbations varies as √ρL^{5}sin^{5}θ along a magnetic field line (where θ is colatitude and L the L-shell number and the cut-off frequency, associated with the Klein-Gordon form, displays an astonishing variation with distance along a field line (see Eqs. 35 and 37 of the text, in the case of a dipole magnetic field. We compute the eigenvalues and eigenfunctions for the Earth's dipole field which are relevant to geomagnetic pulsations.
Adiabatic cooling of a single trapped ion
Poulsen, Gregers
2012-01-01
We present experimental results on adiabatic cooling of a single 40Ca+ ion in a linear radiofrequency trap. After a period of laser cooling, the secular frequency along the rf-field-free axis is adiabatically lowered by nearly a factor of eight from 583 kHz to 75 kHz. For an ion originally Doppler laser cooled to a temperature of 0.65 +/- 0.03 mK, a temperature of 87 +/- 7 \\mu K is measured after the adiabatic expansion. Applying the same adiabatic cooling procedure to a single sideband cooled ion in the ground state (P0 = 0.978 +/- 0.002) resulted in a final ground state occupation of 0.947 +/- 0.005. Both results are in excellent agreement with an essentially fully adiabatic behavior. The results have a wide range of perspectives within such diverse fields as ion based quantum information science, high resolution molecular ion spectroscopy and ion chemistry at ultra-low temperatures.
Toroidal dipole excitations in metamolecules formed by interacting plasmonic nanorods
Watson, Derek W; Ruostekoski, Janne; Fedotov, Vassili A; Zheludev, Nikolay I
2015-01-01
We show how the elusive toroidal dipole moment appears as a radiative excitation eigenmode in a metamolecule resonator that is formed by pairs of plasmonic nanorods. We analyze one such nanorod configuration - a toroidal metamolecule. We find that the radiative interactions in the toroidal metamolecule can be qualitatively represented by a theoretical model based on an electric point dipole arrangement. Both a finite-size rod model and the point dipole approximation demonstrate how the toroidal dipole moment is subradiant and difficult to excite by incident light. By means of breaking the geometric symmetry of the metamolecule, the toroidal mode can be excited by linearly polarized light and we provide simple optimization protocols for maximizing the toroidal dipole mode excitation. This opens up possibilities for simplified control and driving of metamaterial arrays consisting of toroidal dipole unit-cell resonators.
30 CFR 57.13010 - Reciprocating-type air compressors.
2010-07-01
... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Reciprocating-type air compressors. 57.13010... Air and Boilers § 57.13010 Reciprocating-type air compressors. (a) Reciprocating-type air compressors... than 25 percent. (b) However, this standard does not apply to reciprocating-type air compressors...
33 CFR 154.826 - Vapor compressors and blowers.
2010-07-01
... system acceptable to the Commandant (CG-522). (b) If a reciprocating or screw-type compressor handles... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Vapor compressors and blowers....826 Vapor compressors and blowers. (a) Each inlet and outlet to a compressor or blower which...
30 CFR 56.13010 - Reciprocating-type air compressors.
2010-07-01
... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Reciprocating-type air compressors. 56.13010... and Boilers § 56.13010 Reciprocating-type air compressors. (a) Reciprocating-type air compressors... than 25 percent. (b) However, this standard does not apply to reciprocating-type air compressors...
Experimental study on the adiabatic shear bands
International Nuclear Information System (INIS)
Four martensitic steels (Z50CDV5 steel, 28CND8 steel, 35NCDV16 steel and 4340 steel) with different hardness between 190 and 600 Hsub(B) (Brinell hardness), have been studied by means of dynamic compressive tests on split Hopkinson pressure bar. Microscopic observations show that the fracture are associated to the development of adiabatic shear bands (except 4340 steel with 190 Hsub(B) hardness). By means of tests for which the deformation is stopped at predetermined levels, the measurement of shear and hardness inside the band and the matrix indicates the chronology of this phenomenon: first the localization of shear, followed by the formation of adiabatic shear band and ultimatly crack initiation and propagation. These results correlated with few simulations by finite elements have permitted to suggest two mecanisms of deformation leading to the formation of adiabatic shear bands in this specific test
Adiabatic Quantum Computing for Random Satisfiability Problems
Hogg, T
2003-01-01
The discrete formulation of adiabatic quantum computing is compared with other search methods, classical and quantum, for random satisfiability (SAT) problems. With the number of steps growing only as the cube of the number of variables, the adiabatic method gives solution probabilities close to one for problem sizes feasible to evaluate. However, for these sizes the minimum energy gaps are fairly large, so may not reflect asymptotic behavior where costs are dominated by tiny gaps. Moreover, the resulting search costs are much higher than other methods, but can be reduced by using fewer steps. Variants of the quantum algorithm that do not match the adiabatic limit give lower costs, on average, and slower growth than the conventional GSAT heuristic method.
Energy efficiency of adiabatic superconductor logic
Takeuchi, Naoki; Yamanashi, Yuki; Yoshikawa, Nobuyuki
2015-01-01
Adiabatic superconductor logic (ASL), including adiabatic quantum-flux-parametron (AQFP) logic, exhibits high energy efficiency because its bit energy can be decreased below the thermal energy through adiabatic switching operations. In the present paper, we present the general scaling laws of ASL and compare the energy efficiency of ASL with those of other energy-efficient logics. Also, we discuss the minimum energy-delay product (EDP) of ASL at finite temperature. Our study shows that there is a maximum temperature at which the EDP can reach the quantum limit given by ħ/2, which is dependent on the superconductor material and the Josephson junction quality, and that it is reasonable to operate ASL at cryogenic temperatures in order to achieve an EDP that approaches ħ/2.
The NLC L-Band Bunch Compressor
International Nuclear Information System (INIS)
The first stage bunch compressor in the NLC injector complex compresses the e+/e- beams from a bunch length of 5 mm rms to 0.5 mm rms at the beam energy of 2 GeV. To obtain this compression ratio, the compressor rf section operates with an rf frequency of 1.4 GHz and a voltage of about 140 MV while a magnetic wiggler is used to generate an R56 = 0.5 m. The bunch compressor is designed to operate with a beam from the damping ring that has a bunch spacing slew of 20ps across the bunch train due to the transient loading in the damping rings. The compressor RF section is required to produce a specific energy profile along the bunch train so that the bunch spacing can be corrected in the compressor bending section. Further, the 1-amp beam heavily loads the compressor linac and beam loading compensation is essential to prevent a phase variation along the bunch train in the downstream linacs. In this paper, we will present simulation results of the beam loading compensation using a ΔT scheme assuming various initial bunch spacing arrangements. We will study the impact of the different compressor energy profiles on the beam energy, energy spread, and bunch length at the IP
Solar concentrator with a toroidal relay module.
Lin, Jhe-Syuan; Liang, Chao-Wen
2015-10-01
III-V multijunction solar cells require solar concentrators with a high concentration ratio to reduce per watt cost and to increase solar energy transforming efficiency. This paper discusses a novel solar concentrator design that features a high concentration ratio, high transfer efficiency, thin profile design, and a high solar acceptance angle. The optical design of the concentrator utilizes a toroidal relay module, which includes both the off-axis relay lens and field lens design in a single concentric toroidal lens shape. The optical design concept of the concentrator is discussed and the simulation results are shown. The given exemplary design has an aspect ratio of 0.24, a high averaged optical concentration ratio 1230×, a maximum efficiency of 76.8%, and the solar acceptance angle of ±0.9°.
Ramsey numbers and adiabatic quantum computing
Gaitan, Frank; Clark, Lane
2011-01-01
The graph-theoretic Ramsey numbers are notoriously difficult to calculate. In fact, for the two-color Ramsey numbers $R(m,n)$ with $m,n\\geq 3$, only nine are currently known. We present a quantum algorithm for the computation of the Ramsey numbers $R(m,n)$. We show how the computation of $R(m,n)$ can be mapped to a combinatorial optimization problem whose solution can be found using adiabatic quantum evolution. We numerically simulate this adiabatic quantum algorithm and show that it correctl...
Staying adiabatic with unknown energy gap
Nehrkorn, J; Ekert, A; Smerzi, A; Fazio, R; Calarco, T
2011-01-01
We introduce an algorithm to perform an optimal adiabatic evolution that operates without an apriori knowledge of the system spectrum. By probing the system gap locally, the algorithm maximizes the evolution speed, thus minimizing the total evolution time. We test the algorithm on the Landau-Zener transition and then apply it on the quantum adiabatic computation of 3-SAT: The result is compatible with an exponential speed-up for up to twenty qubits with respect to classical algorithms. We finally study a possible algorithm improvement by combining it with the quantum Zeno effect.
Complexity of the Quantum Adiabatic Algorithm
Hen, Itay
2013-01-01
The Quantum Adiabatic Algorithm (QAA) has been proposed as a mechanism for efficiently solving optimization problems on a quantum computer. Since adiabatic computation is analog in nature and does not require the design and use of quantum gates, it can be thought of as a simpler and perhaps more profound method for performing quantum computations that might also be easier to implement experimentally. While these features have generated substantial research in QAA, to date there is still a lack of solid evidence that the algorithm can outperform classical optimization algorithms.
Adiabatic Flame Temperature for Combustion of Methane
Directory of Open Access Journals (Sweden)
Rebeca Pupo
2011-01-01
Full Text Available This project calculated the adiabatic flame temperature of a combustion reaction of pure methane and oxygen, assuming that all of the heat liberated by the combustion reaction goes into heating the resulting mixture. Mole fractions of methane to oxygen were computed from 0.05 to 0.95, in increments of 0.05, and then an integral was computed was computed with respect to temperature using the moles of product produced or leftover moles of reactants from the starting mole fraction times the specific heat of each respective gas. The highest adiabatic flame temperature evaluated, occurred at a mole fraction of 0.35.
Advances in the simulation of toroidal gyro Landau fluid model turbulence
Energy Technology Data Exchange (ETDEWEB)
Waltz, R.E. [General Atomics, San Diego, CA (United States); Kerbel, G.D.; Milovich, J. [Lawrence Livermore National Lab., CA (United States); Hammett, G.W. [Princeton Univ., NJ (United States). Plasma Physics Lab.
1994-12-01
The gyro-Landau fluid (GLF) model equations for toroidal geometry have been recently applied to the study ion temperature gradient (ITG) mode turbulence using the 3D nonlinear ballooning mode representation (BMR). The present paper extends this work by treating some unresolved issues conceming ITG turbulence with adiabatic electrons. Although eddies are highly elongated in the radial direction long time radial correlation lengths are short and comparable to poloidal lengths. Although transport at vanishing shear is not particularly large, transport at reverse global shear, is significantly less. Electrostatic transport at moderate shear is not much effected by inclusion of local shear and average favorable curvature. Transport is suppressed when critical E{times}B rotational shear is comparable to the maximum linear growth rate with only a weak dependence on magnetic shear. Self consistent turbulent transport of toroidal momentum can result in a transport bifurcation at suffciently large r/(Rq). However the main thrust of the new formulation in the paper deals with advances in the development of finite beta GLF models with trapped electron and BMR numerical methods for treating the fast parallel field motion of the untrapped electrons.
Antimicrobial Peptides in Toroidal and Cylindrical Pores
Mihajlovic, Maja; Lazaridis, Themis
2010-01-01
Antimicrobial peptides (AMPs) are small, usually cationic peptides, which permeabilize biological membranes. Their mechanism of action is still not well understood. Here we investigate the preference of alamethicin and melittin for pores of different shapes, using molecular dynamics (MD) simulations of the peptides in pre-formed toroidal and cylindrical pores. When an alamethicin hexamer is initially embedded in a cylindrical pore, at the end of the simulation the pore remains cylindrical or ...
Kinetic Damping of Toroidal Alfven Eigenmodes
Energy Technology Data Exchange (ETDEWEB)
G.Y. Fu; H.L. Berk; A. Pletzer
2005-05-03
The damping of Toroidal Alfven Eigenmodes in JET plasmas is investigated by using a reduced kinetic model. Typically no significant damping is found to occur near the center of the plasma due to mode conversion to kinetic Alfven waves. In contrast, continuum damping from resonance near the plasma edge may be significant, and when it is, it gives rise to damping rates that are compatible with the experimental observations.
Toroidal geometry subroutines for MORSE-CG
International Nuclear Information System (INIS)
The equations, coding, and procedures that are required to include a torus in the Combinatorial Geometry subroutines of the MORSE-CG code are described. The derivation and solutions of the quartic equation that describes a torus along with additional subroutines and the modifications to existing subroutines required to carry out the transport of neutrons and gamma rays in toroidal geometry are presented. The input requirements and a sample problem are included
Stellarator approach to toroidal plasma confinement
International Nuclear Information System (INIS)
An overview is presented of the development and current status of the stellarator approach to controlled thermonuclear confinement. Recent experimental, theoretical, and systems developments have made this concept a viable option for the evolution of the toroidal confinement program. Some experimental study of specific problems associated with departure from two-dimensional symmetry must be undertaken before the full advantages and opportunities of steady-state, net-current-free operation can be realized
Commercial concepts for adiabatic compressed air energy storage
Energy Technology Data Exchange (ETDEWEB)
Freund, Sebastian [General Electric Global Research, Garching (Germany); Schainker, Robert [Electric Power Research Institute, Palo Alto, CA (United States); Moreau, Robert [General Electric Oil and Gas, Florence (Italy)
2012-07-01
Adiabatic compressed air energy storage (ACAES) systems offer the potential for efficient large-scale energy storage, almost approaching values typical for pumped hydro. In an ACAES plant, the heat of compression is stored and utilized during the expansion of the air instead of firing natural gas like in commercial CAES. However, no ACAES plants have been commercialized due to challenges with respect to the cost and the heat storage technology. In this study, conducted by EPRI, GE Global Research and GE Oil and Gas, several concepts for ACAES plants are analyzed and their efficiency, complexity and technical risk compared. The components selected for the plants are available either off-the-shelf or near-commercial within a short development time and without the high costs associated with developing a new generation of large custom-made compressors and turbines. The most promising concept for near-term commercialization and low costs turns out to be a two-stage, low-temperature ACAES system. A regenerative (solid) and a recuperative (liquid) thermal storage system have been designed and analyzed for this concept, with the result that the liquid-recuperative system offers a much lower cost and comparable performance. Performance and cost targets for the concepts are 100 MW output per plant for 6 h with a round-trip efficiency above 60% and a capital cost of about $1000/kW. Selections of the turbomachinery for the compression and expansion train from General Electric Oil and Gas are presented for several plant options along with their expansion power range (25..100 MW), round-trip efficiency (66%..70%) and preliminary capital cost estimates (1100..1200 $/kW).
CFD Analysis of Oil Discharge Rate in Rotary Compressor
Deng, Liying; Liang, Shebing; Liu, Qiang; Wu, Jun; Xu, Jia
2012-01-01
Oil discharge rate in rotary compressor has a significant influence on heat transfer performance of condenser and evaporator in air conditioning system. In order to find out the influence which caused by the structure of rotary compressor on the oil discharge rate, the flow field of rotary compressor has been calculated by VOF method and the lubricant distribution in rotary compressor can be obtained. At the same time, Oil discharge rate in rotary compressor at different operating conditions ...
Measurement and Calibration of Centrifugal Compressor Pressure Scanning Instrumentation
Rivas, Jose R; Lou, Fangyuan; Harrison, Herbert "Trey"; Key, Nicole
2015-01-01
The compressor is a key component of a jet engine necessary to compress air for the combustion process. Research to optimize compressor efficiency through the understanding of air flow behavior has led to increased efforts in creating modern compressor test facilities. In collaboration with Honeywell, the High Speed Compressor facility at Zucrow Laboratories has built a centrifugal compressor test cell with instrumentation to measure the temperatures and pressures of the air flow. This facili...
Analysis of reciprocating compressor piston rod failures
Energy Technology Data Exchange (ETDEWEB)
Tripp, H.A.; Drosjack, M.J.
1984-02-01
This report presents the analysis of five piston rod failures which occurred on reciprocating compressors. Calculations are shown for rod stress which includes nominal rod loading sources as well as additional loads due to unusual pressure losses in the compressor valves, flexure of the rods due to misalignment, and manufacturing errors. The additional loads were incorporated on the basis of field measurements. The stress values are used with Baquin's equation to produce fatigue life curves for the rods. Based on the calculations, recommendations for modified rods were made. The calculation procedures are described in a manner which will permit their application to other reciprocating compressors.
Compressor Part I: Measurement and Design Modeling
Directory of Open Access Journals (Sweden)
Thomas W. Bein
1999-01-01
method used to design the 125-ton compressor is first reviewed and some related performance curves are predicted based on a quasi-3D method. In addition to an overall performance measurement, a series of instruments were installed on the compressor to identify where the measured performance differs from the predicted performance. The measurement techniques for providing the diagnostic flow parameters are also described briefly. Part II of this paper provides predictions of flow details in the areas of the compressor where there were differences between the measured and predicted performance.
Improved Regenerative Sorbent-Compressor Refrigerator
Jones, Jack A.
1992-01-01
Conceptual regenerative sorbent-compressor refrigerator attains regeneration efficiency and, therefore, overall power efficiency and performance greater than conventional refrigerators. Includes two fluid loops. In one, CH2FCF3 (R134a) ciculates by physical adsorption and desorption in four activated-charcoal sorption compressors. In other, liquid or gas coolant circulated by pump. Wave of regenerative heating and cooling propagates cyclically like peristatic wave among sorption compressors and associated heat exchangers. Powered by electricity, oil, gas, solar heat, or waste heat. Used as air conditioners, refrigerators, and heat pumps in industrial, home, and automotive applications.
Compressor ported shroud for foil bearing cooling
Elpern, David G.; McCabe, Niall; Gee, Mark
2011-08-02
A compressor ported shroud takes compressed air from the shroud of the compressor before it is completely compressed and delivers it to foil bearings. The compressed air has a lower pressure and temperature than compressed outlet air. The lower temperature of the air means that less air needs to be bled off from the compressor to cool the foil bearings. This increases the overall system efficiency due to the reduced mass flow requirements of the lower temperature air. By taking the air at a lower pressure, less work is lost compressing the bearing cooling air.
THERMODYNAMIC DESIGN OF CENTRIFUGAL COMPRESSOR FOR TURBOCHARGER
Sonawane Shubham*, Sondkar Pratik, Qasim Siddiqui, Phirke Indraneel, Prof. R. P. Kakde
2016-01-01
The purpose of a turbocharger is to increase the power output of an engine by supplying compressed air to the engine intake manifold so that fuel can be burnt efficiently. In this work, thermodynamic design of a high pressure ratio centrifugal compressor, for 75 kW class engines, was carried out. A pressure ratio of 2.8 was considered with a compressor rotational speed of 60,000 RPM. The compressor was designed for vane less diffuser. The impeller designs were obtained using ci...
Aspects of Tokamak toroidal magnet protection
Energy Technology Data Exchange (ETDEWEB)
Green, R.W.; Kazimi, M.S.
1979-07-01
Simple but conservative geometric models are used to estimate the potential for damage to a Tokamak reactor inner wall and blanket due to a toroidal magnet field collapse. The only potential hazard found to exist is due to the MHD pressure rise in a lithium blanket. A survey is made of proposed protection methods for superconducting toroidal magnets. It is found that the two general classifications of protection methods are thermal and electrical. Computer programs were developed which allow the toroidal magnet set to be modeled as a set of circular filaments. A simple thermal model of the conductor was used which allows heat transfer to the magnet structure and which includes the effect of temperature dependent properties. To be effective in large magnets an electrical protection system should remove at least 50% of the stored energy in the protection circuit assuming that all of the superconductor in the circuit quenches when the circuit is activated. A protection system design procedure based on this criterion was developed.
Beede, William L.; Kovach, Karl
1948-01-01
The J33-A-23 compressor with a 34-blade impeller was operated at ambient inlet temperature and an inlet pressure of 14 inches mercury absolute over a range of equivalent impeller speeds from 6000 to 11,750 rpm. Additional runs at equivalent speeds of 7,000, 10,000, and 11,750 rpm and ambient inlet temperature were made at inlet pressures of 5 and 10 inches mercury absolute. The results of this investigation are compared with those of the J33-A-23 compressor with a 17-blade impeller. At the design equivalent speed of 11,750 rpm the 533-A-23 compressor with a 34-blade impeller had a peak pressure ratio of 4.49 at an equivalent weight flow of 82.4 pounds per second and an adiabatic temperature-rise efficiency of 0.740. The maximum equivalent flow at design speed was 91.8 pounds per second. The peak efficiency at design speed (0.757) occurred at an equivalent weight flow of 85.5 pounds per second. The maximum adiabatic temperature- rise efficiency of 0.773 was obtained at an equivalent impeller speed of 10,000 rpm, an equivalent weight flow of 65.8 pounds per second, and a pressure ratio of 3.27. At equivalent impeller speeds of.l0,000 and 11,75O rpm a decrease in inlet pressure resulted in a decrease in maximum equivalent weight flow, peak pressure ratio, and peak adiabatic temperature- rise efficiency.
Semi adiabatic theory of seasonal Markov processes
Energy Technology Data Exchange (ETDEWEB)
Talkner, P. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)
1999-08-01
The dynamics of many natural and technical systems are essentially influenced by a periodic forcing. Analytic solutions of the equations of motion for periodically driven systems are generally not known. Simulations, numerical solutions or in some limiting cases approximate analytic solutions represent the known approaches to study the dynamics of such systems. Besides the regime of weak periodic forces where linear response theory works, the limit of a slow driving force can often be treated analytically using an adiabatic approximation. For this approximation to hold all intrinsic processes must be fast on the time-scale of a period of the external driving force. We developed a perturbation theory for periodically driven Markovian systems that covers the adiabatic regime but also works if the system has a single slow mode that may even be slower than the driving force. We call it the semi adiabatic approximation. Some results of this approximation for a system exhibiting stochastic resonance which usually takes place within the semi adiabatic regime are indicated. (author) 1 fig., 8 refs.
Quantum Pumping and Adiabatic Transport in Nanostructures
Wakker, G.M.M.
2011-01-01
This thesis consists of a theoretical exploration of quantum transport phenomena and quantum dynamics in nanostructures. Specifically, we investigate adiabatic quantum pumping of charge in several novel types of nanostructures involving open quantum dots or graphene. For a bilayer of graphene we fin
Adiabatic transition probability for a tangential crossing
Watanabe, Takuya
2006-01-01
We consider a time-dependent Schrödinger equation whose Hamiltonian is a $2\\times 2$ real symmetric matrix. We study, using an exact WKB method, the adiabatic limit of the transition probability in the case where several complex eigenvalue crossing points accumulate to one real point.
Improving the positive feedback adiabatic logic familiy
Directory of Open Access Journals (Sweden)
J. Fischer
2004-01-01
Full Text Available Positive Feedback Adiabatic Logic (PFAL shows the lowest energy dissipation among adiabatic logic families based on cross-coupled transistors, due to the reduction of both adiabatic and non-adiabatic losses. The dissipation primarily depends on the resistance of the charging path, which consists of a single p-channel MOSFET during the recovery phase. In this paper, a new logic family called Improved PFAL (IPFAL is proposed, where all n- and pchannel devices are swapped so that the charge can be recovered through an n-channel MOSFET. This allows to decrease the resistance of the charging path up to a factor of 2, and it enables a significant reduction of the energy dissipation. Simulations based on a 0.13µm CMOS process confirm the improvements in terms of power consumption over a large frequency range. However, the same simple design rule, which enables in PFAL an additional reduction of the dissipation by optimal transistor sizing, does not apply to IPFAL. Therefore, the influence of several sources of dissipation for a generic IPFAL gate is illustrated and discussed, in order to lower the power consumption and achieve better performance.
Recent adiabaticity results from orbit calculations
International Nuclear Information System (INIS)
There has been much activity recently in an attempt to find a straightforward method of predicting the limits of adiabatic behavior in high-beta magnetic-mirror configurations. The particle-orbit code TIBRO was used to obtain numerical results on nonadiabatic behavior with which the predictions of theoretical expressions can be compared. These results are summarized. (MOW)
Virtual Training of Compressor Control Room Project
National Aeronautics and Space Administration — MYMIC will analyze, design, develop and evaluate the Virtual Control Room Compressor Station (VCoR-CS) training system. VCoR-CS will provide procedural...
Refrigeration system having dual suction port compressor
Energy Technology Data Exchange (ETDEWEB)
Wu, Guolian
2016-01-05
A cooling system for appliances, air conditioners, and other spaces includes a compressor, and a condenser that receives refrigerant from the compressor. The system also includes an evaporator that receives refrigerant from the condenser. Refrigerant received from the condenser flows through an upstream portion of the evaporator. A first portion of the refrigerant flows to the compressor without passing through a downstream portion of the evaporator, and a second portion of the refrigerant from the upstream portion of the condenser flows through the downstream portion of the evaporator after passing through the upstream portion of the evaporator. The second portion of the refrigerant flows to the compressor after passing through the downstream portion of the evaporator. The refrigeration system may be configured to cool an appliance such as a refrigerator and/or freezer, or it may be utilized in air conditioners for buildings, motor vehicles, or other such spaces.
High Speed Compressor for Subcooling Propellants Project
National Aeronautics and Space Administration — Propellant densification systems for LH2 require compression systems that develop significant head. In the past this has required multiple stages of compressors...
Communication: Adiabatic and non-adiabatic electron-nuclear motion: Quantum and classical dynamics
Albert, Julian; Kaiser, Dustin; Engel, Volker
2016-05-01
Using a model for coupled electronic-nuclear motion we investigate the range from negligible to strong non-adiabatic coupling. In the adiabatic case, the quantum dynamics proceeds in a single electronic state, whereas for strong coupling a complete transition between two adiabatic electronic states takes place. It is shown that in all coupling regimes the short-time wave-packet dynamics can be described using ensembles of classical trajectories in the phase space spanned by electronic and nuclear degrees of freedom. We thus provide an example which documents that the quantum concept of non-adiabatic transitions is not necessarily needed if electronic and nuclear motion is treated on the same footing.
Adiabatic and Non-adiabatic quenches in a Spin-1 Bose Einstein Condensate
Boguslawski, Matthew; Hebbe Madhusudhana, Bharath; Anquez, Martin; Robbins, Bryce; Barrios, Maryrose; Hoang, Thai; Chapman, Michael
2016-05-01
A quantum phase transition (QPT) is observed in a wide range of phenomena. We have studied the dynamics of a spin-1 ferromagnetic Bose-Einstein condensate for both adiabatic and non-adiabatic quenches through a QPT. At the quantum critical point (QCP), finite size effects lead to a non-zero gap, which makes an adiabatic quench possible through the QPT. We experimentally demonstrate such a quench, which is forbidden at the mean field level. For faster quenches through the QCP, the vanishing energy gap causes the reaction timescale of the system to diverge, preventing the system from adiabatically following the ground state. We measure the temporal evolution of the spin populations for different quench speeds and determine the exponents characterizing the scaling of the onset of excitations, which are in good agreement with the predictions of Kibble-Zurek mechanism.
Towards Centrifugal Compressor Stages Virtual Testing
Guidotti, Emanuele
2014-01-01
Flow features inside centrifugal compressor stages are very complicated to simulate with numerical tools due to the highly complex geometry and varying gas conditions all across the machine. For this reason, a big effort is currently being made to increase the fidelity of the numerical models during the design and validation phases. Computational Fluid Dynamics (CFD) plays an increasing role in the assessment of the performance prediction of centrifugal compressor stages. Historically, CFD wa...
Aerodynamic instabilities in transonic centrifugal compressor
Buffaz, Nicolas; Trébinjac, Isabelle
2014-01-01
International audience This paper presents the analysis of the instabilities inception in a transonic centrifugal com-pressor for different rotation speeds. The analysis was conducted from experimental results obtained with unsteady pressure sensors implanted in the inducer, vaneless diffuser and vaned diffuser. Beyond the stability limit the compressor enters into a deep surge without any precursor, whatever the speed. The surge process is initiated in the vaned diffuser by a massive boun...
Thermal Equilibrium and Wet Gas Compressor Performance
Aalvik, Marthe
2011-01-01
The wet gas performance model established for this master s thesis is based on results achieved from a single stage, low pressure ratio, centrifugal compressor set up at NTNU. Water droplets are injected to the flow right before the inlet. The GMF varies from 0.9 to 0.65 throughout the experiments preformed. Compressor performance is achieved by simulations in HYSYS with atmospheric inlet conditions. The importance of accurate measurements is evident to achieve the correct performance. A lite...
Preliminary aerothermal design of axial compressors
Piscopo, Giovanni
2013-01-01
This dissertation documents a compressor preliminary design study conducted by the author in fulfilment of his MSc thesis requirements. The compressor is intended for a new development engine within the 20Klbf thrust category, planned to be used on a short-haul aircraft, namely the ERJ-190. A market research suggests that there exists a definite opportunity for a commercially profitable engine within this thrust class. Furthermore, the proposed new engine is projected to out...
Energy Saving Potential in Existing Compressors
Cipollone, Roberto; Vittorini, Diego
2014-01-01
The Compressed Air Sector (CAS) is responsible for a relevant part of energy consumption, accounting for a mean 10% of the world-wide electricity needs. This ensures about the importance of the CAS issue when sustainability, in terms of energy saving and CO2 emissions reduction, is in question. Since the compressors alone account for a mean 15% of the industry overall electricity consumption, it appears vital to pay attention towards machine performances. The paper deals with compressor techn...
The dynamic instability of adiabatic blast waves
Ryu, Dongsu; Vishniac, Ethan T.
1991-01-01
Adiabatic blastwaves, which have a total energy injected from the center E varies as t(sup q) and propagate through a preshock medium with a density rho(sub E) varies as r(sup -omega) are described by a family of similarity solutions. Previous work has shown that adiabatic blastwaves with increasing or constant postshock entropy behind the shock front are susceptible to an oscillatory instability, caused by the difference between the nature of the forces on the two sides of the dense shell behind the shock front. This instability sets in if the dense postshock layer is sufficiently thin. The stability of adiabatic blastwaves with a decreasing postshock entropy is considered. Such blastwaves, if they are decelerating, always have a region behind the shock front which is subject to convection. Some accelerating blastwaves also have such region, depending on the values of q, omega, and gamma where gamma is the adiabatic index. However, since the shock interface stabilizes dynamically induced perturbations, blastwaves become convectively unstable only if the convective zone is localized around the origin or a contact discontinuity far from the shock front. On the other hand, the contact discontinuity of accelerating blastwaves is subject to a strong Rayleigh-Taylor instability. The frequency spectra of the nonradial, normal modes of adiabatic blastwaves have been calculated. The results have been applied to the shocks propagating through supernovae envelopes. It is shown that the metal/He and He/H interfaces are strongly unstable against the Rayleigh-Taylor instability. This instability will induce mixing in supernovae envelopes. In addition the implications of this work for the evolution of planetary nebulae is discussed.
Macroscopic electromagnetic response of metamaterials with toroidal resonances
Savinov, V; Zheludev, N I
2013-01-01
Toroidal dipole, first described by Ia. B. Zeldovich [Sov. Phys. JETP 33, 1184 (1957)], is a distinct electromagnetic excitation that differs both from the electric and the magnetic dipoles. It has a number of intriguing properties: static toroidal nuclear dipole is responsible for parity violation in atomic spectra; interactions between static toroidal dipole and oscillating magnetic dipole are claimed to violate Newton's Third Law while non-stationary charge-current configurations involving toroidal multipoles have been predicted to produce vector potential in the absence of electromagnetic fields. Existence of the toroidal response in metamaterials was recently demonstrated and is now a growing field of research. However, no direct analytical link has yet been established between the transmission and reflection of macroscopic electromagnetic media and toroidal dipole excitations. To address this essential gap in electromagnetic theory we have developed an analytical approach linking microscopic and macrosc...
An overview on research developments of toroidal continuously variable transmissions
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
As environmental protection agencies enact new regulations for automotive fuel economy and emission, the toroidal continuously variable transmissions (CVTs) keep on contribute to the advent of system technologies for better fuel consumption of automobiles with internal combustion engines (ICE). Toroidal CVTs use infinitely adjustable drive ratios instead of stepped gears to achieve optimal performance. Toroidal CVTs are one of the earliest patents to the automotive world but their torque capacities and reliability have limitations in the past. New developments and implementations in the control strategies, and several key technologies have led to development of more robust toroidal CVTs, which enables more extensive automotive application of toroidal CTVs. This paper concerns with the current development, upcoming and progress set in the context of the past development and the traditional problems associated with toroidal CVTs.
Toroid cavity/coil NMR multi-detector
Gerald, II, Rex E.; Meadows, Alexander D.; Gregar, Joseph S.; Rathke, Jerome W.
2007-09-18
An analytical device for rapid, non-invasive nuclear magnetic resonance (NMR) spectroscopy of multiple samples using a single spectrometer is provided. A modified toroid cavity/coil detector (TCD), and methods for conducting the simultaneous acquisition of NMR data for multiple samples including a protocol for testing NMR multi-detectors are provided. One embodiment includes a plurality of LC resonant circuits including spatially separated toroid coil inductors, each toroid coil inductor enveloping its corresponding sample volume, and tuned to resonate at a predefined frequency using a variable capacitor. The toroid coil is formed into a loop, where both ends of the toroid coil are brought into coincidence. Another embodiment includes multiple micro Helmholtz coils arranged on a circular perimeter concentric with a central conductor of the toroid cavity.
Macroscopic electromagnetic response of metamaterials with toroidal resonances
Savinov, V.; Fedotov, V. A.; Zheludev, N. I.
2013-01-01
Toroidal dipole, first described by Ia. B. Zeldovich [Sov. Phys. JETP 33, 1184 (1957)], is a distinct electromagnetic excitation that differs both from the electric and the magnetic dipoles. It has a number of intriguing properties: static toroidal nuclear dipole is responsible for parity violation in atomic spectra; interactions between static toroidal dipole and oscillating magnetic dipole are claimed to violate Newton's Third Law while non-stationary charge-current configurations involving...
Perturbation to Mei symmetry and adiabatic invariants for Hamilton systems
Institute of Scientific and Technical Information of China (English)
Ding Ning; Fang Jian-Hui
2008-01-01
Based on the concept of adiabatic invariant,this paper studies the perturbation to Mei symmetry and adiabatic invariants for Hamilton systems.The exact invaxiants of Mei symmetry for the system without perturbation are given.The perturbation to Mei symmetry is discussed and the adiabatic invariants induced from the perturbation to Mei symmetry of the system are obtained.
Adiabatic Liquid Piston Compressed Air Energy Storage
Petersen, Tage; Elmegaard, Brian; Pedersen, Allan Schrøder
2013-01-01
This project investigates the potential of a Compressed Air Energy Storage system (CAES system). CAES systems are used to store mechanical energy in the form of compressed air. The systems use electricity to drive the compressor at times of low electricity demand with the purpose of converting the mechanical energy into electricity at times of high electricity demand. Two such systems are currently in operation; one in Germany (Huntorf) and one in the USA (Macintosh, Alabama). In both cases, ...
Toroidal plasma enhanced CVD of diamond films
International Nuclear Information System (INIS)
An inductively coupled toroidal plasma source is used as an alternative to microwave plasmas for chemical vapor deposition of diamond films. The source, operating at a frequency of 400 kHz, synthesizes diamond films from a mixture of argon, methane, and hydrogen. The toroidal design has been adapted to create a highly efficient environment for diamond film deposition: high gas temperature and a short distance from the sample to the plasma core. Using a toroidal plasma geometry operating in the medium frequency band allows for efficient (≈90%) coupling of AC line power to the plasma and a scalable path to high-power and large-area operation. In test runs, the source generates a high flux of atomic hydrogen over a large area, which is favorable for diamond film growth. Using a deposition temperature of 900–1050 °C and a source to sample distance of 0.1–2.0 cm, diamond films are deposited onto silicon substrates. The results showed that the deposition rate of the diamond films could be controlled using the sample temperature and source to sample spacing. The results also show the films exhibit good-quality polycrystalline diamond as verified by Raman spectroscopy, x-ray diffraction, and scanning electron microscopy. The scanning electron microscopy and x-ray diffraction results show that the samples exhibit diamond (111) and diamond (022) crystallites. The Raman results show that the sp3 peak has a narrow spectral width (FWHM 12 ± 0.5 cm−1) and that negligible amounts of the sp2 band are present, indicating good-quality diamond films
Directory of Open Access Journals (Sweden)
Živić Marija
2014-01-01
Full Text Available Energy and exergy analysis of a Brayton cycle with an ideal gas is given. The irreversibility of the adiabatic processes in turbine and compressor is taken into account through their isentropic efficiencies. The net work per cycle, the thermal efficiency and the two exergy efficiencies are expressed as functions of the four dimensionless variables: the isentropic efficiencies of turbine and compressor, the pressure ratio, and the temperature ratio. It is shown that the maximal values of the net work per cycle, the thermal and the exergy efficiency are achieved when the isentropic efficiencies and temperature ratio are as high as possible, while the different values of pressure ratio that maximize the net work per cycle, the thermal and the exergy efficiencies exist. These pressure ratios increase with the increase of the temperature ratio and the isentropic efficiency of compressor and turbine. The increase of the turbine isentropic efficiency has a greater impact on the increase of the net work per cycle and the thermal efficiency of a Brayton cycle than the same increase of compressor isentropic efficiency. Finally, two goal functions are proposed for thermodynamic optimization of a Brayton cycle for given values of the temperature ratio and the compressor and turbine isentropic efficiencies. The first maximizes the sum of the net work per cycle and thermal efficiency while the second the net work per cycle and exergy efficiency. In both cases the optimal pressure ratio is closer to the pressure ratio that maximizes the net work per cycle.
3D Printing the ATLAS' barrel toroid
Goncalves, Tiago Barreiro
2016-01-01
The present report summarizes my work as part of the Summer Student Programme 2016 in the CERN IR-ECO-TSP department (International Relations – Education, Communication & Outreach – Teacher and Student Programmes). Particularly, I worked closely with the S’Cool LAB team on a science education project. This project included the 3D designing, 3D printing, and assembling of a model of the ATLAS’ barrel toroid. A detailed description of the project' development is presented and a short manual on how to use 3D printing software and hardware is attached.
Polar interface phonons in ionic toroidal systems.
Nguyen, N D; Evrard, R; Stroscio, Michael A
2016-09-01
We use the dielectric continuum model to obtain the polar (Fuchs-Kliewer like) interface vibration modes of toroids made of ionic materials either embedded in a different material or in vacuum, with applications to nanotoroids specially in mind. We report the frequencies of these modes and describe the electric potential they produce. We establish the quantum-mechanical Hamiltonian appropriate for their interaction with electric charges. This Hamiltonian can be used to describe the effect of this interaction on different types of charged particles either inside or outside the torus. PMID:27357246
Plasma current resonance in asymmetric toroidal systems
Energy Technology Data Exchange (ETDEWEB)
Hazeltine, R. D. [Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712 (United States); Catto, Peter J. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, 167 Albany Street, Cambridge, Massachusetts 02139 (United States)
2015-09-15
The well-known singularity in the magnetic differential equation for plasma current in an asymmetric toroidal confinement system is resolved by including in the pressure tensor corrections stemming from finite Larmor radius. The result provides an estimate of the amplitude of spikes in the parallel current that occur on rational magnetic surfaces. Resolution of the singularity is shown to depend on both the ambipolarity condition—the requirement of zero surface-averaged radial current—and the form of the magnetic differential equation near the rational surface.
Toroidal membrane vesicles in spherical confinement
Bouzar, Lila; Müller, Martin Michael
2015-01-01
We investigate the morphology of a toroidal fluid membrane vesicle confined inside a spherical container. The equilibrium shapes are assembled in a geometrical phase diagram as a function of scaled area and reduced volume of the membrane. For small area the vesicle can adopt its free form. When increasing the area, the membrane cannot avoid contact and touches the confining sphere along a circular contact line, which extends to a zone of contact for higher area. The elastic energies of the equilibrium shapes are compared to those of their confined counterparts of spherical topology to predict under which conditions a topology change is favored energetically.
Toroidal membrane vesicles in spherical confinement
Bouzar, Lila; Menas, Ferhat; Müller, Martin Michael
2015-09-01
We investigate the morphology of a toroidal fluid membrane vesicle confined inside a spherical container. The equilibrium shapes are assembled in a geometrical phase diagram as a function of scaled area and reduced volume of the membrane. For small area the vesicle can adopt its free form. When increasing the area, the membrane cannot avoid contact and touches the confining sphere along a circular contact line, which extends to a zone of contact for higher area. The elastic energies of the equilibrium shapes are compared to those of their confined counterparts of spherical topology to predict under which conditions a topology change is favored energetically.
Polar interface phonons in ionic toroidal systems.
Nguyen, N D; Evrard, R; Stroscio, Michael A
2016-09-01
We use the dielectric continuum model to obtain the polar (Fuchs-Kliewer like) interface vibration modes of toroids made of ionic materials either embedded in a different material or in vacuum, with applications to nanotoroids specially in mind. We report the frequencies of these modes and describe the electric potential they produce. We establish the quantum-mechanical Hamiltonian appropriate for their interaction with electric charges. This Hamiltonian can be used to describe the effect of this interaction on different types of charged particles either inside or outside the torus.
Polar interface phonons in ionic toroidal systems
Nguyen, N. D.; Evrard, R.; Stroscio, Michael A.
2016-09-01
We use the dielectric continuum model to obtain the polar (Fuchs–Kliewer like) interface vibration modes of toroids made of ionic materials either embedded in a different material or in vacuum, with applications to nanotoroids specially in mind. We report the frequencies of these modes and describe the electric potential they produce. We establish the quantum-mechanical Hamiltonian appropriate for their interaction with electric charges. This Hamiltonian can be used to describe the effect of this interaction on different types of charged particles either inside or outside the torus.
Drift waves in general toroidal geometry
International Nuclear Information System (INIS)
A model, based on gyro-kinetic ions and fluid electrons, to study drift waves in low-beta [beta = (kinetic pressure)/(magnetic pressure)] stellarator plasmas is presented. The model equations are written in straight-field-line coordinates and are valid for arbitrary, fully three-dimensional configurations with closed, nested magnetic surfaces. An implicit method, coupled with a subcycling technique for the electrons, is used to solve the time-dependent, along-the-field-line equations. Numerical calculations are carried out for a 3-field-period toroidal heliac. The geometrical effects that enter the model equations are calculated and displayed in physical space using advanced visualization techniques
General Atomic's superconducting toroidal field coil concept
International Nuclear Information System (INIS)
General Atomic's concept for a superconducting toroidal field coil is presented. The concept is generic for large tokamak devices, while a specific design is indicated for a 3.8 meter (major radius) ignition/burn machine. The concept utilizes bath cooled NbTi conductor to generate a peak field of 10 tesla at 4.2 K. The design is simple and straightforward, requires a minimum of developmental effort, and draws extensively upon the perspective of past experience in the design and construction of large superconducting magnets for high energy physics. Thus, the primary emphasis is upon economy, reliability, and expeditious construction scheduling. (author)
Pulsar Wind Nebulae with Thick Toroidal Structure
Chevalier, Roger A.; Reynolds, Stephen P.
2011-01-01
We investigate a class of pulsar wind nebulae that show synchrotron emission from a thick toroidal structure. The best studied such object is the small radio and X-ray nebula around the Vela pulsar, which can be interpreted as the result of interaction of a mildly supersonic inward flow with the recent pulsar wind. Such a flow near the center of a supernova remnant can be produced in a transient phase when the reverse shock reaches the center of the remnant. Other nebulae with a thick toroida...
Adiabatic quantum simulation of quantum chemistry.
Babbush, Ryan; Love, Peter J; Aspuru-Guzik, Alán
2014-10-13
We show how to apply the quantum adiabatic algorithm directly to the quantum computation of molecular properties. We describe a procedure to map electronic structure Hamiltonians to 2-body qubit Hamiltonians with a small set of physically realizable couplings. By combining the Bravyi-Kitaev construction to map fermions to qubits with perturbative gadgets to reduce the Hamiltonian to 2-body, we obtain precision requirements on the coupling strengths and a number of ancilla qubits that scale polynomially in the problem size. Hence our mapping is efficient. The required set of controllable interactions includes only two types of interaction beyond the Ising interactions required to apply the quantum adiabatic algorithm to combinatorial optimization problems. Our mapping may also be of interest to chemists directly as it defines a dictionary from electronic structure to spin Hamiltonians with physical interactions.
Adiabatic state preparation study of methylene
Energy Technology Data Exchange (ETDEWEB)
Veis, Libor, E-mail: libor.veis@jh-inst.cas.cz; Pittner, Jiří, E-mail: jiri.pittner@jh-inst.cas.cz [J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejškova 3, 18223 Prague 8 (Czech Republic)
2014-06-07
Quantum computers attract much attention as they promise to outperform their classical counterparts in solving certain type of problems. One of them with practical applications in quantum chemistry is simulation of complex quantum systems. An essential ingredient of efficient quantum simulation algorithms are initial guesses of the exact wave functions with high enough fidelity. As was proposed in Aspuru-Guzik et al. [Science 309, 1704 (2005)], the exact ground states can in principle be prepared by the adiabatic state preparation method. Here, we apply this approach to preparation of the lowest lying multireference singlet electronic state of methylene and numerically investigate preparation of this state at different molecular geometries. We then propose modifications that lead to speeding up the preparation process. Finally, we decompose the minimal adiabatic state preparation employing the direct mapping in terms of two-qubit interactions.
Adiabatic Quantum Optimization for Associative Memory Recall
Directory of Open Access Journals (Sweden)
Hadayat eSeddiqi
2014-12-01
Full Text Available Hopfield networks are a variant of associative memory that recall patterns stored in the couplings of an Ising model. Stored memories are conventionally accessed as fixed points in the network dynamics that correspond to energetic minima of the spin state. We show that memories stored in a Hopfield network may also be recalled by energy minimization using adiabatic quantum optimization (AQO. Numerical simulations of the underlying quantum dynamics allow us to quantify AQO recall accuracy with respect to the number of stored memories and noise in the input key. We investigate AQO performance with respect to how memories are stored in the Ising model according to different learning rules. Our results demonstrate that AQO recall accuracy varies strongly with learning rule, a behavior that is attributed to differences in energy landscapes. Consequently, learning rules offer a family of methods for programming adiabatic quantum optimization that we expect to be useful for characterizing AQO performance.
Quantum adiabatic evolution with energy degeneracy levels
Zhang, Qi
2016-01-01
A classical-kind phase-space formalism is developed to address the tiny intrinsic dynamical deviation from what is predicted by Wilczek-Zee theorem during quantum adiabatic evolution on degeneracy levels. In this formalism, the Hilbert space and the aggregate of degenerate eigenstates become the classical-kind phase space and a high-dimensional subspace in the phase space, respectively. Compared with the previous analogous study by a different method, the current result is qualitatively different in that the first-order deviation derived here is always perpendicular to the degeneracy subspace. A tripod-scheme Hamiltonian with two degenerate dark states is employed to illustrate the adiabatic deviation with degeneracy levels.
Ramsey numbers and adiabatic quantum computing.
Gaitan, Frank; Clark, Lane
2012-01-01
The graph-theoretic Ramsey numbers are notoriously difficult to calculate. In fact, for the two-color Ramsey numbers R(m,n) with m, n≥3, only nine are currently known. We present a quantum algorithm for the computation of the Ramsey numbers R(m,n). We show how the computation of R(m,n) can be mapped to a combinatorial optimization problem whose solution can be found using adiabatic quantum evolution. We numerically simulate this adiabatic quantum algorithm and show that it correctly determines the Ramsey numbers R(3,3) and R(2,s) for 5≤s≤7. We then discuss the algorithm's experimental implementation, and close by showing that Ramsey number computation belongs to the quantum complexity class quantum Merlin Arthur.
Microwave produced plasma in a Toroidal Device
Singh, A. K.; Edwards, W. F.; Held, E. D.
2010-11-01
A currentless toroidal plasma device exhibits a large range of interesting basic plasma physics phenomena. Such a device is not in equilibrium in a strict magneto hydrodynamic sense. There are many sources of free energy in the form of gradients in plasma density, temperature, the background magnetic field and the curvature of the magnetic field. These free energy sources excite waves and instabilities which have been the focus of studies in several devices in last two decades. A full understanding of these simple plasmas is far from complete. At Utah State University we have recently designed and installed a microwave plasma generation system on a small tokamak borrowed from the University of Saskatchewan, Saskatoon, Canada. Microwaves are generated at 2.45 GHz in a pulsed dc mode using a magnetron from a commercial kitchen microwave oven. The device is equipped with horizontal and vertical magnetic fields and a transformer to impose a toroidal electric field for current drive. Plasmas can be obtained over a wide range of pressure with and without magnetic fields. We present some preliminary measurements of plasma density and potential profiles. Measurements of plasma temperature at different operating conditions are also presented.
Aspects of Tokamak toroidal magnet protection
International Nuclear Information System (INIS)
Simple but conservative geometric models are used to estimate the potential for damage to a Tokamak reactor inner wall and blanket due to a toroidal magnet field collapse. The ofly potential hazard found to exist is due to the MHD pressure rise in a lithium blanket. A survey is made of proposed protection methods for superconducting torgidal magnets. It is found that the two general classificatigls of protectign methods are thermal and electrical. Computer programs were developed which aldow the toroidal magnet set to be modeled as a set of circular filaments. A simple thermal model of the conductor was used which allows heat transfer to the magnet structure and which includes the effect of temperature dependent properties. To be effective in large magnets an electrical protection system should remove at least 50% of the stored energy in the protection circuit assuming that all of the superconductor in the circuit quenches when the circuit is activated. A protection system design procedure based on this criterion was developed
Propulsion using the electron spiral toroid
International Nuclear Information System (INIS)
A new propulsion method is proposed which could potentially reduce propellant needed for space travel by three orders of magnitude. It uses the newly patented electron spiral toroid (EST), which stores energy as magnetic field energy. The EST is a hollow toroid of electrons, all spiraling in parallel paths in a thin outer shell. The electrons satisfy the coupling condition, forming an electron matrix. Stability is assured as long as the coupling condition is satisfied. The EST is held in place with a small external electric field; without an external magnetic field. The EST system is contained in a vacuum chamber. The EST can be thought of as an energetic entity, with electrons at 10,000 electron volts. Propulsion would not use combustion, but would heat propellant through elastic collisions with the EST surface and eject them for thrust. Chemical rocket combustion heats propellant to 4000 deg. C; an EST will potentially heat the propellant 29,000 times as much, reducing propellant needs accordingly. The thrust can be turned ON and OFF. The EST can be recharged as needed
Adiabatic graph-state quantum computation
International Nuclear Information System (INIS)
Measurement-based quantum computation (MBQC) and holonomic quantum computation (HQC) are two very different computational methods. The computation in MBQC is driven by adaptive measurements executed in a particular order on a large entangled state. In contrast in HQC the system starts in the ground subspace of a Hamiltonian which is slowly changed such that a transformation occurs within the subspace. Following the approach of Bacon and Flammia, we show that any MBQC on a graph state with generalized flow (gflow) can be converted into an adiabatically driven holonomic computation, which we call adiabatic graph-state quantum computation (AGQC). We then investigate how properties of AGQC relate to the properties of MBQC, such as computational depth. We identify a trade-off that can be made between the number of adiabatic steps in AGQC and the norm of H-dot as well as the degree of H, in analogy to the trade-off between the number of measurements and classical post-processing seen in MBQC. Finally the effects of performing AGQC with orderings that differ from standard MBQC are investigated. (paper)
Transport and Dynamics in Toroidal Fusion Systems
Energy Technology Data Exchange (ETDEWEB)
Schnack, Dalton D
2006-05-16
This document reports the successful completion of the OFES Theory Milestone for FY2005, namely, Perform parametric studies to better understand the edge physics regimes of laboratory experiments. Simulate at increased resolution (up to 20 toroidal modes), with density evolution, late into the nonlinear phase and compare results from different types of edge modes. Simulate a single case including a study of heat deposition on nearby material walls. The linear stability properties and nonlinear evolution of Edge Localized Modes (ELMs) in tokamak plasmas are investigated through numerical computation. Data from the DIII-D device at General Atomics (http://fusion.gat.com/diii-d/) is used for the magnetohydrodynamic (MHD) equilibria, but edge parameters are varied to reveal important physical effects. The equilibrium with very low magnetic shear produces an unstable spectrum that is somewhat insensitive to dissipation coefficient values. Here, linear growth rates from the non-ideal NIMROD code (http://nimrodteam.org) agree reasonably well with ideal, i.e. non-dissipative, results from the GATO global linear stability code at low toroidal mode number (n) and with ideal results from the ELITE edge linear stability code at moderate to high toroidal mode number. Linear studies with a more realistic sequence of MHD equilibria (based on DIII-D discharge 86166) produce more significant discrepancies between the ideal and non-ideal calculations. The maximum growth rate for the ideal computations occurs at toroidal mode index n=10, whereas growth rates in the non-ideal computations continue to increase with n unless strong anisotropic thermal conduction is included. Recent modeling advances allow drift effects associated with the Hall electric field and gyroviscosity to be considered. A stabilizing effect can be observed in the preliminary results, but while the distortion in mode structure is readily apparent at n=40, the growth rate is only 13% less than the non-ideal MHD
Performance evaluation of high speed compressors for high speed multipliers
Directory of Open Access Journals (Sweden)
Nirlakalla Ravi
2011-01-01
Full Text Available This paper describes high speed compressors for high speed parallel multipliers like Booth Multiplier, Wallace Tree Multiplier in Digital Signal Processing (DSP. This paper presents 4-3, 5-3, 6-3 and 7-3 compressors for high speed multiplication. These compressors reduce vertical critical path more rapidly than conventional compressors. A 5-3 conventional compressor can take four steps to reduce bits from 5 to 3, but the proposed 5-3 takes only 2 steps. These compressors are simulated with H-Spice at a temperature of 25°C at a supply voltage 2.0V using 90nm MOSIS technology. The Power, Delay, Power Delay Product (PDP and Energy Delay Product (EDP of the compressors are calculated to analyze the total propagation delay and energy consumption. All the compressors are designed with half adder and full Adders only.
Quench propagation and protection analysis of the ATLAS Toroids
Dudarev, A; ten Kate, H H J; Baynham, D Elwyn; Courthold, M J D; Lesmond, C
2000-01-01
The ATLAS superconducting magnet system consists of the Barrel Toroid, two End Cap Toroids and the Central Solenoid. However, the Toroids of eight coils each are magnetically separate systems to the Central Solenoid. The Toroids are electrically connected in series and energized by a single power supply. The quench protection system is based on the use of relatively small external dump resistances in combination with quench-heaters activated after a quench event detection to initiate the internal dump of stored energy in all the coils. A rather strong quench-back effect due to eddy-currents in the coil casings at the transport current decay is beneficial for the quench protection efficiency in the event of heater failures. The quench behaviour of the ATLAS Toroids was computer simulated for normal operation of the quench protection system and its complete non-operation (failure) mode. (3 refs).
Non-adiabatic effects in near-adiabatic mixed-field orientation and alignment
Maan, Anjali; Ahlawat, Dharamvir Singh; Prasad, Vinod
2016-11-01
We present a theoretical study of the impact of a pair of moderate electric fields tilted an angle with respect to one another on a molecule. As a prototype, we consider a molecule with large rotational constant (with corresponding small rotational period) and moderate dipole moment. Within rigid-rotor approximation, the time-dependent Schrodinger equation is solved using fourth-order Runge-Kutta method. We have analysed that lower rotational states are significantly influenced by variation in pulse durations, the tilt angle between the fields and also on the electric field strengths. We also suggest a control scheme of how the rotational dynamics, orientation and alignment of a molecule can be enhanced by a combination of near-adiabatic pulses in comparision to non-adiabatic or adiabatic pulses.
An aerodynamic design and numerical investigation of transonic centrifugal compressor stage
Yi, Weilin; Ji, Lucheng; Tian, Yong; Shao, Weiwei; Li, Weiwei; Xiao, Yunhan
2011-09-01
In the present paper, the design of a transonic centrifugal compressor stage with the inlet relative Mach number about 1.3 and detailed flow field investigation by three-dimensional CFD are described. Firstly the CFD program was validated by an experimental case. Then the preliminary aerodynamic design of stage completed through in-house one-dimensional code. Three types of impellers and two sets of stages were computed and analyzed. It can be found that the swept shape of leading edge has prominent influence on the performance and can enlarge the flow range. Similarly, the performance of the stage with swept impeller is better than others. The total pressure ratio and adiabatic efficiency of final geometry achieve 7:1 and 80% respectively. The vane diffuser with same airfoils along span increases attack angle at higher span, and the local flow structure and performance is deteriorated.
Perturbing macroscopic magnetohydrodynamic stability for toroidal plasmas
Comer, Kathryn J.
We have introduced a new perturbative technique to rapidly explore the dependence of long wavelength ideal magnetohydrodynamic (MHD) instabilities on equilibrium profiles, shaping properties, and wall parameters. Traditionally, these relations are studied with numerical parameter scans using computationally intensive stability codes. Our perturbative technique first finds the equilibrium and stability using traditional methods. Subsequent small changes in the original equilibrium parameters change the stability. We quickly find the new stability with an expansion of the energy principle, rather than with another run of the stability codes. We first semi-analytically apply the technique to the screw pinch after eliminating compressional Alfven wave effects. The screw pinch results validate the approach, but also indicate that allowable perturbations to equilibria with certain features may be restricted. Next, we extend the approach to toroidal geometry using experimental equilibria and a simple constructed equilibrium, with the ideal MHD stability code GATO. Stability properties are successfully predicted from perturbed toroidal equilibria when only the vacuum beyond the plasma is perturbed (through wall parameter variations), rather than the plasma itself. Small plasma equilibrium perturbations to both experimental and simple equilibria result in very large errors to the predicted stability, and valid results are found only over a narrow range of most perturbations. Despite the large errors produced when changing plasma parameters, the wall perturbations revealed two useful applications of this technique. Because the calculations are non-iterative matrix multiplications, the convergence issues that can disrupt a full MHD stability code are absent. Marginal stability, therefore, is much easier to find with the perturbative technique. Also, the perturbed results can be input as the initial guess for the eigenvalue for a full stability code, and improve subsequent
Coupled Thermodynamic Behavior of New Screw Compressors Rotors Profile
Directory of Open Access Journals (Sweden)
Arístides Rivera Torres
2010-05-01
Full Text Available The article displays an evaluation of the thermodynamic behavior of screw compressor rotors with new profiles, obtained with the help of the Scorpath 2000 software. This allows predicting precisely the operation of the compressor, as well as its thermodynamic evaluation, under equal conditions, with the work of other compressors fitted with rotor profiles of other kinds.
40 CFR 60.482-3a - Standards: Compressors.
2010-07-01
... Administrator. (j) Any existing reciprocating compressor in a process unit which becomes an affected facility... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Standards: Compressors. 60.482-3a..., Reconstruction, or Modification Commenced After November 7, 2006 § 60.482-3a Standards: Compressors. (a)...
40 CFR 60.482-3 - Standards: Compressors.
2010-07-01
... designation, annually, and at other times requested by the Administrator. (j) Any existing reciprocating... Standards: Compressors. (a) Each compressor shall be equipped with a seal system that includes a barrier... paragraphs (h), (i), and (j) of this section. (b) Each compressor seal system as required in paragraph...
Advanced Compressor Designs for High Energy Petawatt Pulse Generation
Energy Technology Data Exchange (ETDEWEB)
Fittinghoff, D N; Wattellier, B; Barty, C P J
2003-09-09
We discuss compressor designs for a proposed multikilojoule, sub-picosecond beamline at the National Ignition Facility. A novel grating configuration reduces the size of the compressor chamber. Optimization of the design leads to a 4.7 x 1.4 x 0.4 m{sup 3} minimum compressor volume.
Cold Climate Heat Pumps Using Tandem Compressors
Energy Technology Data Exchange (ETDEWEB)
Shen, Bo [ORNL; Abdelaziz, Omar [ORNL; Rice, C Keith [ORNL; Baxter, Van D [ORNL
2016-01-01
In cold climate zones, e.g. ASHRAE climate regions IV and V, conventional electric air-source heat pumps (ASHP) do not work well, due to high compressor discharge temperatures, large pressure ratios and inadequate heating capacities at low ambient temperatures. Consequently, significant use of auxiliary strip heating is required to meet the building heating load. We introduce innovative ASHP technologies as part of continuing efforts to eliminate auxiliary strip heat use and maximize heating COP with acceptable cost-effectiveness and reliability. These innovative ASHP were developed using tandem compressors, which are capable of augmenting heating capacity at low temperatures and maintain superior part-load operation efficiency at moderate temperatures. Two options of tandem compressors were studied; the first employs two identical, single-speed compressors, and the second employs two identical, vapor-injection compressors. The investigations were based on system modeling and laboratory evaluation. Both designs have successfully met the performance criteria. Laboratory evaluation showed that the tandem, single-speed compressor ASHP system is able to achieve heating COP = 4.2 at 47 F (8.3 C), COP = 2.9 at 17 F (-8.3 C), and 76% rated capacity and COP = 1.9 at -13 F (-25 C). This yields a HSPF = 11.0 (per AHRI 210/240). The tandem, vapor-injection ASHP is able to reach heating COP = 4.4 at 47 F, COP = 3.1 at 17 F, and 88% rated capacity and COP = 2.0 at -13 F. This yields a HSPF = 12.0. The system modeling and further laboratory evaluation are presented in the paper.
Design and Prototyping of Micro Centrifugal Compressor
Institute of Scientific and Technical Information of China (English)
Shimpei Mizuki; Gaku Minorikawa; Toshiyuki Hirano; Yuichiro Asaga; Naoki Yamaguchi; Yutaka Ohta; Eisuke Outa
2003-01-01
In order to establish the design methodology of ultra micro centrifugal compressor, which is the most important component of ultra micro gas turbine unit, a 10 times of the final target size model was designed, prototyped and tested. The problems to be solved for downsizing were examined and 2-dimensional impeller was chosen as the first model due to its productivity. The conventional 1D prediction method, CFD and the inverse design were attempted. The prototyped compressor was driven by using a turbocharger and the performance characteristics were measured.
Active compressor engine silencer reduces exhaust noise
International Nuclear Information System (INIS)
An active industrial silencer on a compressor engine at a Tenneco Gas station has reduced low-frequency 'rumbling' noise by 8 dB during trials while lowering backpressure about 90$. This 8 dB reduction of the piston firing frequency corresponds to a more than 80% decrease in emitted acoustic power. The silencing unit, installed on one of six engines at the station near Eden, N.Y., continues in operation. Based on the results, the manufacturer is identifying additional compressor sites for further tests. This paper reviews this project
Helicity of a toroidal vortex with swirl
Bannikova, E. Yu.; Kontorovich, V. M.; Poslavsky, S. A.
2016-04-01
Based on the solutions of the Bragg-Hawthorne equation, we discuss the helicity of a thin toroidal vortex in the presence of swirl, orbital motion along the torus directrix. The relation between the helicity and circulations along the small and large linked circumferences (the torus directrix and generatrix) is shown to depend on the azimuthal velocity distribution in the core of the swirling ring vortex. In the case of nonuniform swirl, this relation differs from the well-known Moffat relation, viz., twice the product of such circulations multiplied by the number of linkages. The results can find applications in investigating the vortices in planetary atmospheres and the motions in the vicinity of active galactic nuclei.
Helicity of the toroidal vortex with swirl
Bannikova, Elena Yu; Poslavsky, Sergey A
2016-01-01
On the basis of solutions of the Bragg-Hawthorne equations we discuss the helicity of thin toroidal vortices with the swirl - the orbital motion along the torus diretrix. It is shown that relationship of the helicity with circulations along the small and large linked circles - directrix and generatrix of the torus - depends on distribution of the azimuthal velocity in the core of the swirling vortex ring. In the case of non-homogeneous swirl this relationship differs from the well-known Moffat relationship - the doubled product of such circulations multiplied by the number of links. The results can be applied to vortices in planetary atmospheres and to vortex movements in the vicinity of active galactic nuclei.
Fluid interaction with spinning toroidal tanks
Fester, D. A.; Anderson, J. E.
1977-01-01
An experimental study was conducted to evaluate propellant behavior in spinning torroidal tanks that could be used in a retropropulsion system of an advanced outer-planet Pioneer orbiter. Information on propellant slosh and settling and on ullage orientation and stability was obtained. The effects of axial acceleration, spin rate, spin-rate change, and spacecraft wobble, both singly and in combination, were evaluated using a one-eighth scale transparent tank in one-g and low-g environments. Liquid loadings ranged from 5% to 96% full. The impact of a surface tension acquisition device was assessed by comparison with bare-tank results. The testing simulated the behavior of the fluorine/hydrazine and nitrogen textroxide/monomethylhydrazine propellants. Results are presented that indicate that no major fluid behavior problems would be encountered with any of the four propellants in the toroidal tanks of a spin-stabilized orbiter spacecraft.
The theory of toroidally confined plasmas
White, Roscoe B
2014-01-01
This graduate level textbook develops the theory of magnetically confined plasma, with the aim of bringing the reader to the level of current research in the field of thermonuclear fusion. It begins with the basic concepts of magnetic field description, plasma equilibria and stability, and goes on to derive the equations for guiding center particle motion in an equilibrium field. Topics include linear and nonlinear ideal and resistive modes and particle transport. It is of use to workers in the field of fusion both for its wide-ranging account of tokamak physics and as a kind of handbook or formulary. This edition has been extended in a number of ways. The material on mode-particle interactions has been reformulated and much new information added, including methodology for Monte Carlo implementation of mode destabilization. These results give explicit means of carrying out mode destabilization analysis, in particular for the dangerous fishbone mode. A new chapter on cyclotron motion in toroidal geometry has ...
Epithelial Proliferation on Curved Toroidal Surfaces
Chang, Ya-Wen; Cruz, Ricardo; Fragkopoulos, Alexandros; Marquez, Samantha; Garcia, Andres; Fernandez-Nieves, Alberto
Cellular environment influences a multitude of cellular functions by providing chemical and physical signals that modulate cell behavior, dynamics, development, and eventually survival. In strongly interacting epithelial cells, cells coordinate their behavior to respond to mechanical constraints in 2D. Local differences in tissue tension has also been shown to impact cell reproduction within an epithelial-cell sheet. Much less is known about how cells respond to out-of-plane curvatures. Here, we describe the proliferation of MDCK on toroidal hydrogel substrates, which unlike spheres or planes, have regions of both positive and negative Gaussian curvature. Additionally, the range of curvatures can be controlled by varying the size and aspect ratio of the torus, allowing us to quantify the relation between substrate curvature and cell proliferation.
Nonideal magnetohydrodynamic instabilities and toroidal magnetic confinement
International Nuclear Information System (INIS)
The marked divergence of experimentally observed plasma instability phenomena from the predictions of ideal magnetohydrodynamics led in the early 1960s to the formulations of finite-resistivity stability theory. Beginning in the 1970s, advanced plasma diagnostics have served to establish a detailed correspondence between the predictions of the finite-resistivity theory and experimental plasma behavior - particularly in the case of the resistive kink mode and the tokamak plasma. Nonlinear resistive-kink phenomena have been found to govern the transport of magnetic flux and plasma energy in the reversed-field pinch. The other predicted finite-resistivity instability modes have been more difficult to identify directly and their implications for toroidal magnetic confinement are still unresolved
Nonideal magnetohydrodynamic instabilities and toroidal magnetic confinement
Energy Technology Data Exchange (ETDEWEB)
Furth, H.P.
1985-05-01
The marked divergence of experimentally observed plasma instability phenomena from the predictions of ideal magnetohydrodynamics led in the early 1960s to the formulations of finite-resistivity stability theory. Beginning in the 1970s, advanced plasma diagnostics have served to establish a detailed correspondence between the predictions of the finite-resistivity theory and experimental plasma behavior - particularly in the case of the resistive kink mode and the tokamak plasma. Nonlinear resistive-kink phenomena have been found to govern the transport of magnetic flux and plasma energy in the reversed-field pinch. The other predicted finite-resistivity instability modes have been more difficult to identify directly and their implications for toroidal magnetic confinement are still unresolved.
Damping of toroidal ion temperature gradient modes
Energy Technology Data Exchange (ETDEWEB)
Sugama, H. [National Inst. for Fusion Science, Toki, Gifu (Japan)
1999-04-01
The temporal evolution of linear toroidal ion temperature gradient (ITG) modes is studied based on a kinetic integral equation including an initial condition. It is shown how to evaluate the analytic continuation of the integral kernel as a function of a complex-valued frequency, which is useful for analytical and numerical calculations of the asymptotic damping behavior of the ITG mode. In the presence of the toroidal {nabla}B-curvature drift, the temporal dependence of the density and potential perturbations consists of normal modes and a continuum mode, which correspond to contributions from poles and from an integral along a branch cut, respectively, of the Laplace-transformed potential function of the complex-valued frequency. The normal modes have exponential time dependence with frequencies and growth rates determined by the dispersion relation while the continuum mode, which has a ballooning structure, shows a power law decay {proportional_to} t{sup -2} in the asymptotic limit, where t is the time variable. Therefore, the continuum mode dominantly describes the long-time asymptotic behavior of the density and potential perturbations for the stable system where all normal modes have negative growth rates. By performing proper analytic continuation for the homogeneous version of the kinetic integral equation, dependences of the normal modes` growth rate, real frequency, and eigenfunction on {eta}{sub i} (the ratio of the ion temperature gradient to the density gradient), k{sub {theta}} (the poloidal wavenumber), s (the magnetic shear parameter), and {theta}{sub k} (the ballooning angle corresponding to the minimum radial wavenumber) are numerically obtained for both stable and unstable cases. (author)
Bond selective chemistry beyond the adiabatic approximation
Energy Technology Data Exchange (ETDEWEB)
Butler, L.J. [Univ. of Chicago, IL (United States)
1993-12-01
One of the most important challenges in chemistry is to develop predictive ability for the branching between energetically allowed chemical reaction pathways. Such predictive capability, coupled with a fundamental understanding of the important molecular interactions, is essential to the development and utilization of new fuels and the design of efficient combustion processes. Existing transition state and exact quantum theories successfully predict the branching between available product channels for systems in which each reaction coordinate can be adequately described by different paths along a single adiabatic potential energy surface. In particular, unimolecular dissociation following thermal, infrared multiphoton, or overtone excitation in the ground state yields a branching between energetically allowed product channels which can be successfully predicted by the application of statistical theories, i.e. the weakest bond breaks. (The predictions are particularly good for competing reactions in which when there is no saddle point along the reaction coordinates, as in simple bond fission reactions.) The predicted lack of bond selectivity results from the assumption of rapid internal vibrational energy redistribution and the implicit use of a single adiabatic Born-Oppenheimer potential energy surface for the reaction. However, the adiabatic approximation is not valid for the reaction of a wide variety of energetic materials and organic fuels; coupling between the electronic states of the reacting species play a a key role in determining the selectivity of the chemical reactions induced. The work described below investigated the central role played by coupling between electronic states in polyatomic molecules in determining the selective branching between energetically allowed fragmentation pathways in two key systems.
Adiabatic Regularization for Gauge Field and the Conformal Anomaly
Chu, Chong-Sun
2016-01-01
We construct and provide the adiabatic regularization method for a $U(1)$ gauge field in a conformally flat spacetime by quantizing in the canonical formalism the gauge fixed $U(1)$ theory with mass terms for the gauge fields and the ghost fields. We show that the adiabatic expansion for the mode functions and the adiabatic vacuum can be defined in a similar way using WKB-type solutions as the scalar fields. As an application of the adiabatic method, we compute the trace of the energy momentum tensor and reproduces the known result for the conformal anomaly obtained by the other regularization methods. The availability of the adiabatic expansion scheme for gauge field allows one to study the renormalization of the de-Sitter space maximal superconformal Yang-Mills theory using the adiabatic regularization method.
Accuracy vs run time in adiabatic quantum search
Rezakhani, A T; Lidar, D A
2010-01-01
Adiabatic quantum algorithms are characterized by their run time and accuracy. The relation between the two is essential for quantifying adiabatic algorithmic performance, yet is often poorly understood. We study the dynamics of a continuous time, adiabatic quantum search algorithm, and find rigorous results relating the accuracy and the run time. Proceeding with estimates, we show that under fairly general circumstances the adiabatic algorithmic error exhibits a behavior with two discernible regimes: the error decreases exponentially for short times, then decreases polynomially for longer times. We show that the well known quadratic speedup over classical search is associated only with the exponential error regime. We illustrate the results through examples of evolution paths derived by minimization of the adiabatic error. We also discuss specific strategies for controlling the adiabatic error and run time.
Adiabatic quantum algorithm for search engine ranking
Garnerone, Silvano; Lidar, Daniel A
2011-01-01
We propose an adiabatic quantum algorithm to evaluate the PageRank vector, the most widely used tool in ranking the relative importance of internet pages. We present extensive numerical simulations which provide evidence that this quantum algorithm outputs any component of the PageRank vector-and thus the ranking of the corresponding webpage-in a time which scales polylogarithmically in the number of webpages. This would constitute an exponential speed-up with respect to all known classical algorithms designed to evaluate the PageRank.
On adiabatic perturbations in the ekpyrotic scenario
Linde, A.; Mukhanov, V.; Vikman, A.
2010-02-01
In a recent paper, Khoury and Steinhardt proposed a way to generate adiabatic cosmological perturbations with a nearly flat spectrum in a contracting Universe. To produce these perturbations they used a regime in which the equation of state exponentially rapidly changed during a short time interval. Leaving aside the singularity problem and the difficult question about the possibility to transmit these perturbations from a contracting Universe to the expanding phase, we will show that the methods used in Khoury are inapplicable for the description of the cosmological evolution and of the process of generation of perturbations in this scenario.
On adiabatic perturbations in the ekpyrotic scenario
Linde, A; Vikman, A
2009-01-01
In a recent paper arXiv:0910.2230, Khoury and Steinhardt proposed a way to generate adiabatic cosmological perturbations with a nearly flat spectrum in a contracting Universe. To produce these perturbations they used a regime in which the equation of state exponentially rapidly changed during a short time interval. Leaving aside the singularity problem and the difficult question about the possibility to transmit these perturbations from a contracting Universe to the expanding phase, we will show that the methods used in arXiv:0910.2230 are inapplicable for the description of the cosmological evolution and of the process of generation of perturbations in this scenario.
Adiabatic chaos in the spin orbit problem
Benettin, Giancarlo; Guzzo, Massimiliano; Marini, Valerio
2008-05-01
We provide evidences that the angular momentum of a symmetric rigid body in a spin orbit resonance can perform large scale chaotic motions on time scales which increase polynomially with the inverse of the oblateness of the body. This kind of irregular precession appears as soon as the orbit of the center of mass is non-circular and the angular momentum of the body is far from the principal directions with minimum (maximum) moment of inertia. We also provide a quantitative explanation of these facts by using the theory of adiabatic invariants, and we provide numerical applications to the cases of the 1:1 and 1:2 spin orbit resonances.
Hypergraph Ramsey Numbers and Adiabatic Quantum Algorithm
Qu, Ri; Bao, Yan-ru
2012-01-01
Gaitan and Clark [Phys. Rev. Lett. 108, 010501 (2012)] have recently presented a quantum algorithm for the computation of the Ramsey numbers R(m, n) using adiabatic quantum evolution. We consider that the two-color Ramsey numbers R(m, n; r) for r-uniform hypergraphs can be computed by using the similar ways in [Phys. Rev. Lett. 108, 010501 (2012)]. In this comment, we show how the computation of R(m, n; r) can be mapped to a combinatorial optimization problem whose solution be found using adi...
Generalized Ramsey numbers through adiabatic quantum optimization
Ranjbar, Mani; Macready, William G.; Clark, Lane; Gaitan, Frank
2016-09-01
Ramsey theory is an active research area in combinatorics whose central theme is the emergence of order in large disordered structures, with Ramsey numbers marking the threshold at which this order first appears. For generalized Ramsey numbers r( G, H), the emergent order is characterized by graphs G and H. In this paper we: (i) present a quantum algorithm for computing generalized Ramsey numbers by reformulating the computation as a combinatorial optimization problem which is solved using adiabatic quantum optimization; and (ii) determine the Ramsey numbers r({{T}}m,{{T}}n) for trees of order m,n = 6,7,8, most of which were previously unknown.
Adiabatic fission barriers in superheavy nuclei
Jachimowicz, P.; Kowal, M; Skalski, J.
2016-01-01
Using the microscopic-macroscopic model based on the deformed Woods-Saxon single-particle potential and the Yukawa-plus-exponential macroscopic energy we calculated static fission barriers $B_{f}$ for 1305 heavy and superheavy nuclei $98\\leq Z \\leq 126$, including even - even, odd - even, even - odd and odd - odd systems. For odd and odd-odd nuclei, adiabatic potential energy surfaces were calculated by a minimization over configurations with one blocked neutron or/and proton on a level from ...
Dark Energy and Dark Matter from an additional adiabatic fluid
Dunsby, Peter K. S.; Luongo, Orlando; Reverberi, Lorenzo
2016-01-01
The Dark Sector is described by an additional barotropic fluid which evolves adiabatically during the universe's history and whose adiabatic exponent $\\gamma$ is derived from the standard definitions of specific heats. Although in general $\\gamma$ is a function of the redshift, the Hubble parameter and its derivatives, we find that our assumptions lead necessarily to solutions with $\\gamma = $ constant in a FLRW universe. The adiabatic fluid acts effectively as the sum of two distinct compone...
A quantum search algorithm based on partial adiabatic evolution
Institute of Scientific and Technical Information of China (English)
Zhang Ying-Yu; Hu He-Ping; Lu Song-Feng
2011-01-01
This paper presents and implements a specified partial adiabatic search algorithm on a quantum circuit. It studies the minimum energy gap between the first excited state and the ground state of the system Hamiltonian and it finds that, in the case of M=1, the algorithm has the same performance as the local adiabatic algorithm. However, the algorithm evolves globally only within a small interval, which implies that it keeps the advantages of global adiabatic algorithms without losing the speedup of the local adiabatic search algorithm.
Magnesium Diboride Superconducting Coils for Adiabatic Demagnetization Refrigerators (ADR's) Project
National Aeronautics and Space Administration — For Adiabatic Demagnetization Refrigerators (ADRs) in space applications, it is desirable to have very light weight, small diameter, high current density...
Toroidal Spiral Strings in Higher-dimensional Spacetime
Igata, Takahisa
2010-01-01
We report on our progress in research of separability of the Nambu-Goto equation for test strings with a symmetric configuration in a shape of toroidal spiral in a five-dimensional Kerr-AdS black hole. In particular, for a Hopf loop string which is a special class of the toroidal spirals, we show the complete separation of variables occurs in two cases, Kerr background and Kerr-AdS background with equal angular momenta. We also obtain the dynamical solution for the Hopf loop around a black hole and for the general toroidal spiral in Minkowski background.
Toroidal dipole resonances in the relativistic random phase approximation
Vretenar, D; Ring, P
2002-01-01
The isoscalar toroidal dipole strength distributions in spherical nuclei are calculated in the framework of a fully consistent relativistic random phase approximation, based on effective mean-field Lagrangians with nonlinear meson self-interaction terms. It is suggested that the recently observed "low-lying component of the isoscalar dipole mode" might in fact correspond to the toroidal giant dipole resonance. Although predicted by several theoretical models, the existence of toroidal resonances has not yet been confirmed in experiment. In the present analysis the vortex dynamics of these states is displayed by the corresponding velocity fields.
Kinetic effect of toroidal rotation on the geodesic acoustic mode
Energy Technology Data Exchange (ETDEWEB)
Guo, W., E-mail: wfguo@ipp.ac.cn; Ye, L.; Zhou, D.; Xiao, X. [Institute of Plasma Physics, Chinese Academy of Science, Hefei, Anhui 230031 (China); Wang, S. [Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)
2015-01-15
Kinetic effects of the toroidal rotation on the geodesic acoustic mode are theoretically investigated. It is found that when the toroidal rotation increases, the damping rate increases in the weak rotation regime due to the rotation enhancement of wave-particle interaction, and it decreases in the strong rotation regime due to the reduction of the number of resonant particles. Theoretical results are consistent with the behaviors of the geodesic acoustic mode recently observed in DIII-D and ASDEX-Upgrade. The kinetic damping effect of the rotation on the geodesic acoustic mode may shed light on the regulation of turbulence through the controlling the toroidal rotation.
Performance of a Folded-Strip Toroidally Wound Induction Machine
DEFF Research Database (Denmark)
Jensen, Bogi Bech; Jack, Alan G.; Atkinson, Glynn J.;
2011-01-01
This paper presents the measured experimental results from a four-pole toroidally wound induction machine, where the stator is constructed as a pre-wound foldable strip. It shows that if the machine is axially restricted in length, the toroidally wound induction machine can have substantially...... shorter stator end-windings than conventionally wound induction machines, and hence that a toroidally wound induction machine can have lower losses and a higher efficiency. The paper also presents the employed construction method, which emphasizes manufacturability, and highlights the advantages...
Laser-induced production of large carbon-based toroids
International Nuclear Information System (INIS)
We report on the production of large carbon-based toroids (CBTs) from fullerenes. The process involves two-step laser irradiation of a mixed fullerene target (76% C60, 22% C70). Transmission electron microscopy (TEM) clearly identifies toroidal-shaped structures as well as Q-shaped constructs. The typical diameters of the CBTs are ∼0.2-0.3 μm with tubular diameters of ∼50-100 nm, but toroids as wide as 0.5 μm are observed making them nanostructures on the verge of being microstructures
Compressor Foundation Analysis Tool(COFANTO)
Eijk, A.; Lentzen, S.S.K; Zuada Coelho, B.E.; Galanti, F.M.B.
2012-01-01
Reciprocating compressors are generally supported on a heavy concrete foundation. In spite of the large inertia and stiffness of the foundation, problems can occur due to interaction between the mechanical installation and the foundation. Two types of problems may occur. In the first type, the inter
2010-07-01
... air course or to the surface and equipped with sensors to monitor for heat and for carbon monoxide or smoke. The sensors shall deenergize power to the compressor, activate a visual and audible alarm located... every 31 days, sensors installed to monitor for carbon monoxide shall be calibrated with a...
Knowledge Based Design of Axial Flow Compressor
Directory of Open Access Journals (Sweden)
Dinesh kumar.R
2015-05-01
Full Text Available In the aerospace industry with highly competitive market the time to design and delivery is shortening every day. Pressure on delivering robust product with cost economy is in demand in each development. Even though technology is older, it is new for each customer requirement and highly non-liner to fit one in another place. Gas turbine is considered one of a complex design in the aircraft system. It involves experts to be grouped with designers of various segments to arrive the best output. The time is crucial to achieve a best design and it needs knowledge automation incorporated with CAD/CAE tools. In the present work an innovative idea in the form of Knowledge Based Engineering for axial compressor is proposed, this includes the fundamental design of axial compressor integrated with artificial intelligence in the form of knowledge capturing and programmed with high level language (Visual Basis.Net and embedded into CATIA v5. This KBE frame work eases out the design and modeling of axial compressor design and produces 3D modeling for further flow simulation with fluid dynamic in Ansys-Fluent. Most of the aerospace components are developed through simulation driven product development and in this case it is established for axial compressor.
Positive feedback stabilization of centrifugal compressor surge
Willems, Frank; Heemels, W.P.M.H.; Jager, de Bram; Stoorvogel, Anton A.
2002-01-01
Stable operation of axial and centrifugal compressors is limited towards low mass flows due to the occurrence of surge. The stable operating region can be enlarged by active control. In this study, we use a control valve which is fully closed in the desired operating point and only opens to stabiliz
40 CFR 65.112 - Standards: Compressors.
2010-07-01
... 40 Protection of Environment 15 2010-07-01 2010-07-01 false Standards: Compressors. 65.112 Section 65.112 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED... barrier fluid system and that prevents leakage of process fluid to the atmosphere except as provided...
Measurements of satellite refrigerator compressor power consumption and efficiency
International Nuclear Information System (INIS)
Each of the thirty compressors installed around the ring and at switchyard is an oil-injected, two-stage, Mycom screw compressor, driven by either a 350 hp or 400 hp motor. The reader is referred to TM1198 by John Satti for a detailed description of these compressors and the associated equipment. Since the power consumed by these compressors is a major operating expense for our accelerator, we were interested in measuring the power consumption and efficiency of our compressors. Two compressors were studied in detail - one having a GE 350 hp motor (F0 No. 2) and one a new GE 400 hp high efficiency motor (F0 No. 1). Data were taken for each compressor with the high stage always fully loaded. These data and values calculated from the data are tabulated
Adiabatic cooling of solar wind electrons
Sandbaek, Ornulf; Leer, Egil
1992-01-01
In thermally driven winds emanating from regions in the solar corona with base electron densities of n0 not less than 10 exp 8/cu cm, a substantial fraction of the heat conductive flux from the base is transfered into flow energy by the pressure gradient force. The adiabatic cooling of the electrons causes the electron temperature profile to fall off more rapidly than in heat conduction dominated flows. Alfven waves of solar origin, accelerating the basically thermally driven solar wind, lead to an increased mass flux and enhanced adiabatic cooling. The reduction in electron temperature may be significant also in the subsonic region of the flow and lead to a moderate increase of solar wind mass flux with increasing Alfven wave amplitude. In the solar wind model presented here the Alfven wave energy flux per unit mass is larger than that in models where the temperature in the subsonic flow is not reduced by the wave, and consequently the asymptotic flow speed is higher.
Odessa pumps now certified on Blackmer compressors
Energy Technology Data Exchange (ETDEWEB)
Anon.
2009-09-15
Some quantity of product recovered from wellheads and tank batteries will undoubtedly escape, be vented or flared off into the atmosphere. In order to solve this problem, field operators are considering the use of vapour-recovery units (VRUs) at the wellhead. To date, only 7,000 to 9,000 VRUs have been installed in the oil and natural gas production sector in the United States. Blackmer, a global supplier of reciprocating-compressor technology, is working through Odessa Pumps to promote the use of its HD and NG Series Oil-Free Reciprocating Gas Compressors. Odessa Pumps is a specialist in providing turnkey solutions for many types of pump and compressor applications. Blackmer's non-lubricated designs provide a full distance piece compartment between the cylinder and crankcase. This allows the user maximum control of any vapours that would normally vent into the crankcase uncontrollably on other designs. Blackmer conducted onsite product training at Odessa offices throughout Texas to introduce the key features and benefits that the units can offer in the field. In addition to their environmental advantages in the oilfield for vapour recovery, there is also an economic benefit. Some operators who have installed Blackmer compressors at their wellheads have made back the cost of the unit from the sale of recovered gas and increased oil production in less than 11 days. Blackmer HD and NG Series Reciprocating Gas Compressors are available in either single- or two-stage configurations. They have been designed for maximum performance and reliability under the most severe operating conditions. 1 fig.
International Nuclear Information System (INIS)
Results of experiments on measuring mechanical stresses in a conducting turn of a model of a toroidal tokamak magnet with a strong field and combined adiabatic compression of plasma filament by a photoelastic coating method for pulse magnetic fields up to 10Tl are stated. The photoelastic method is based on that some isotropic transparent materials gain the temporary double refraction property i.e. become anisotropic. A thin layer of an optically active material is coated or glued on the object under investigation. Displacements of corresponding points of the surface of an optically active (photoelastic) layer appear during the surface deformation of the object investigated. Possibility for using photoelastic coating method for diagnostics of the model of the toroidal tokamak magnet with a strong magnetic field and combined adiabatic compression of plasma filament in the range of pulse magnetic fields up to 10Tl is shown. Regimes with fast (t approximately 0.25ms) and slow (t approximately 1.5ms) growths of a magnetic field in the magnet model were investigated
Influence of toroidal rotation on resistive tearing modes in tokamaks
Energy Technology Data Exchange (ETDEWEB)
Wang, S.; Ma, Z. W., E-mail: zwma@zju.edu.cn [Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China)
2015-12-15
Influence of toroidal equilibrium plasma rotation on m/n = 2/1 resistive tearing modes is studied numerically using a 3D toroidal MHD code (CLT). It is found that the toroidal rotation with or without shear can suppress the tearing instability and the Coriolis effect in the toroidal geometry plays a dominant role on the rotation induced stabilization. For a high viscosity plasma (τ{sub R}/τ{sub V} ≫ 1, where τ{sub R} and τ{sub V} represent resistive and viscous diffusion time, respectively), the effect of the rotation shear combined with the viscosity appears to be stabilizing. For a low viscosity plasmas (τ{sub R}/τ{sub V} ≪ 1), the rotation shear shows a destabilizing effect when the rotation is large.
Influence of toroidal rotation on resistive tearing modes in tokamaks
Wang, S.; Ma, Z. W.
2015-12-01
Influence of toroidal equilibrium plasma rotation on m/n = 2/1 resistive tearing modes is studied numerically using a 3D toroidal MHD code (CLT). It is found that the toroidal rotation with or without shear can suppress the tearing instability and the Coriolis effect in the toroidal geometry plays a dominant role on the rotation induced stabilization. For a high viscosity plasma (τR/τV ≫ 1, where τR and τV represent resistive and viscous diffusion time, respectively), the effect of the rotation shear combined with the viscosity appears to be stabilizing. For a low viscosity plasmas (τR/τV ≪ 1), the rotation shear shows a destabilizing effect when the rotation is large.
Toroidicity Dependence of Tokamak Edge Safety Factor and Shear
Institute of Scientific and Technical Information of China (English)
SHIBingren
2002-01-01
In large tokamak device and reactor designs, the relationship between the toroidal current and the edge safety factor is very important because this will determine the eventual device or reactor size according to MHD stability requirements. In many preliminary
Effect of toroidicity during lower hybrid mode conversion
International Nuclear Information System (INIS)
The effect of toroidicity during lower hybrid mode conversion is examined by treating the wave propagation in an inhomogeneous medium as an eigenvalue problem for ω2(m,n),m,n poloidal and toroidal wave numbers. Since the frequency regime near ω2 = ω/sub LH/2 is an accumulation point for the eigenvalue spectrum, the degenerate perturbation technique must be applied. The toroidal eigenmodes are constructed by a zeroth order superposition of monochromatic solutions with different poloidal dependence m, thus they generically exhibit a wide spectrum in k/sub parallel/ for given fixed ω2 even for small inverse aspect ratio epsilon. In case that the average is in the neighborhood of k/sub min/, the minimum wave number for accessibility of the mode conversion regime, it is expected that excitation of toroidal modes rather than geometric optics will determine the wave coupling to the plasma
Numerical solution of quasilinear kinetic diffusion equations in toroidal plasmas
Höök, Lars Josef
2013-01-01
One of the main challenges for the realization of a working fusion power plant is an increased detailed understanding of kinetic phenomena in toroidal plasmas. The tokamak is a toroidal, magnetically confined plasma device and is currently the main line towards a power plant. The spatial and temporal scales in a tokamak plasma are extreme and the only tractable path for quantitative studies is to rely on computer simulations. Present day simulation codes can resolve only some of these scales....
Relation of E1 pygmy and toroidal resonances
Nesterenko, V O; Reinhard, P -G; Kvasil, J
2014-01-01
A possible relation of the low-lying E1 (pygmy resonance) and toroidal strengths is analyzed by using Skyrme-RPA results for the strength functions, transition densities and current fields in $^{208}$Pb. It is shown that the irrotational pygmy motion can appear as a local manifestation of the collective vortical toroidal dipole resonance (TDR) at the nuclear surface. The RPA results are compared to unperturbed (1ph) ones.
Low-aspect-ratio toroidal equilibria of electron clouds
International Nuclear Information System (INIS)
Toroidal electron clouds with a low aspect ratio (as small as 1.3) and lasting for thousands of poloidal rotation periods have been formed in the laboratory. Characteristic toroidal effects like a large inward shift of the minor axis of equipotential contours, elliptical and triangular deformations, etc., have been observed experimentally for the first time. The results of new analytic and numerical investigations of low-aspect-ratio electron cloud equilibria, which reproduce many of the observed features, are also presented
Prediction of Cracking Gas Compressor Performance and Its Application in Process Optimization
Institute of Scientific and Technical Information of China (English)
李绍军; 李凤
2012-01-01
Cracking gas compressor is usually a centrifugal compressor. The information on the performance of a centrifugal compressor under all conditions is not available, which restricts the operation optimization for compressor. To solve this problem, two back propagation (BP) neural networks were introduced to model the performance of a compressor by using the data provided by manufacturer. The input data of the model under other conditions should be corrected according to the similarity theory. The method was used to optimize the system of a cracking gas compressor by embedding the compressor performance model into the ASPEN PLUS model of compressor. The result shows that it is an effective method to optimize the compressor system.
International Nuclear Information System (INIS)
Two older projects associated with very high energy density plasmas, specifically the High Density Field Reversed Configuration and the Liner Plasma Compression Experiment, have been completed. Attention has been turned to compact toroid experiments of more conventional density, and three experiments have been initiated. These include the Coaxial Slow Source Experiment, the Variable Length FRC Experiment, and Variable Angle CthetaP Experiment. In each case, the project was begun in order to provide basic plasma physics information on specific unresolved issues of progammatic importance to the national CT Program
Experimental study of high beta toroidal plasmas
International Nuclear Information System (INIS)
Experiments on the Wisconsin Levitated Toroidal Octupole have produced a wide range of stable high β plasmas with β significantly above single fluid MHD theory predictions. A stable β approx. 8% plasma, twice the fluid limit, is obtained with 5 rho/sub i/ approx. L/sub n/ and tau/sub β/ approx. = 6000 tau/sub Alfven/ = 600 μsec. The enhanced stability is explained with a kinetic treatment that includes the effect of finite ion gyroradius which couples the ballooning mode to an ion drift wave. In a more collisional, large gyroradius (2 rho/sub i/ approx. L/sub n/) regime, a stable β approx. 35% plasma is obtained with a decay time of 1000 Alfven times. Measurement of the equilibrium magnetic field in this regime indicates that the diamagnetic current density is five times smaller than predicted by ideal MHD, probably due to ion gyroviscosity. Particle transport is anomalous and ranges from agreement with the classical diffusion rate at the highest beta, lowest field plasma (B/sub P/ = 200 G), to thirteen times the classical rate in a β=11%, high field plasma (B/sub P/ = 860 G) where the level of enhancement increase with magnetic field. Fluctuations in density, electrostatic potential, and magnetic field have been studied in plasmas with β from 0.1% to 40%
Compact toroid injection into C-2U
Roche, Thomas; Gota, H.; Garate, E.; Asai, T.; Matsumoto, T.; Sekiguchi, J.; Putvinski, S.; Allfrey, I.; Beall, M.; Cordero, M.; Granstedt, E.; Kinley, J.; Morehouse, M.; Sheftman, D.; Valentine, T.; Waggoner, W.; the TAE Team
2015-11-01
Sustainment of an advanced neutral beam-driven FRC for a period in excess of 5 ms is the primary goal of the C-2U machine at Tri Alpha Energy. In addition, a criteria for long-term global sustainment of any magnetically confined fusion reactor is particle refueling. To this end, a magnetized coaxial plasma-gun has been developed. Compact toroids (CT) are to be injected perpendicular to the axial magnetic field of C-2U. To simulate this environment, an experimental test-stand has been constructed. A transverse magnetic field of B ~ 1 kG is established (comparable to the C-2U axial field) and CTs are fired across it. As a minimal requirement, the CT must have energy density greater than that of the magnetic field it is to penetrate, i.e., 1/2 ρv2 >=B2 / 2μ0 . This criteria is easily met and indeed the CTs traverse the test-stand field. A preliminary experiment on C-2U shows the CT also capable of penetrating into FRC plasmas and refueling is observed resulting in a 20 - 30% increase in total particle number per single-pulsed CT injection. Results from test-stand and C-2U experiments will be presented.
Toroidal bubble entrapment under an impacting drop
Thoraval, Marie-Jean; Thoroddsen, Sigurdur T.; Takehara, Kohsei; Etoh, Takeharu Goji
2012-11-01
We use ultra-high-speed imaging and numerical simulations (GERRIS, http://gfs.sf.net) to observe and analyze the formation of up to 14 air tori when a water drop impacts on a thin liquid film of water or other miscible liquids. They form during the early contact between the drop and the pool by the vertical oscillations of the ejecta sheet. They then break in micro-bubble rings by the Rayleigh instability. Their formation is associated with the shedding of an axisymmetric vortex street into the liquid from the free surface. These vorticity structures and their dynamics are made apparent by the dynamics of the micro-bubbles, added seed particles and the difference of refractive index for different liquids in the drop and the pool. More robust entrapments are observed for a thin film of ethanol or methanol. We show that while the non-spherical drop shape is not responsible for the toroidal bubble entrapments, the number of rings is increasing for more oblate drops. Individual bubble entrapments are also observed from azimuthal destabilizations of the neck between the drop and the pool.
Tearing Mode Stability of Evolving Toroidal Equilibria
Pletzer, A.; McCune, D.; Manickam, J.; Jardin, S. C.
2000-10-01
There are a number of toroidal equilibrium (such as JSOLVER, ESC, EFIT, and VMEC) and transport codes (such as TRANSP, BALDUR, and TSC) in our community that utilize differing equilibrium representations. There are also many heating and current drive (LSC and TORRAY), and stability (PEST1-3, GATO, NOVA, MARS, DCON, M3D) codes that require this equilibrium information. In an effort to provide seamless compatibility between the codes that produce and need these equilibria, we have developed two Fortran 90 modules, MEQ and XPLASMA, that serve as common interfaces between these two classes of codes. XPLASMA provides a common equilibrium representation for the heating and current drive applications while MEQ provides common equilibrium and associated metric information needed by MHD stability codes. We illustrate the utility of this approach by presenting results of PEST-3 tearing stability calculations of an NSTX discharge performed on profiles provided by the TRANSP code. Using the MEQ module, the TRANSP equilibrium data are stored in a Fortran 90 derived type and passed to PEST3 as a subroutine argument. All calculations are performed on the fly, as the profiles evolve.
Sawtooth Instability in the Compact Toroidal Hybrid
Herfindal, J. L.; Maurer, D. A.; Hartwell, G. J.; Ennis, D. A.; Knowlton, S. F.
2015-11-01
Sawtooth instabilities have been observed in the Compact Toroidal Hybrid (CTH), a current-carrying stellarator/tokamak hybrid device. The sawtooth instability is driven by ohmic heating of the core plasma until the safety factor drops below unity resulting in the growth of an m = 1 kink-tearing mode. Experiments varying the vacuum rotational transform from 0.02 to 0.13 are being conducted to study sawtooth property dependance on vacuum flux surface structure. The frequency of the sawtooth oscillations increase from 2 kHz to 2.8 kHz solely due the decrease in rise time of the oscillation, the crash time is unchanged. CTH has three two-color SXR cameras, a three-channel 1mm interferometer, and a new bolometer system capable of detecting the signatures of sawtooth instabilities. The new bolometer system consists of two cameras, each containing a pair of diode arrays viewing the plasma directly or through a beryllium filter. Electron temperature measurements are found with the two-color SXR cameras through a ratio of the SXR intensities. Impurity radiation can drastically affect the electron temperature measurement, therefore new filters consisting of aluminum and carbon were selected to avoid problematic line radiation while maximizing the signal for a 100 eV plasma. This work is supported by U.S. Department of Energy Grant No. DE-FG02-00ER54610.
Pseudo-Anosov flows in toroidal manifolds
Barbot, Thierry
2010-01-01
We first prove rigidity results for pseudo-Anosov flows in prototypes of toroidal 3-manifolds: we show that a pseudo-Anosov in a Seifert fibered manifold is up to finite covers topologically conjugate to a geodesic flow. We also show that a pseudo-Anosov flow in a solv manifold is topologically conjugate to a suspension Anosov flow. Then we analyse immersed and embedded incompressible tori in optimal position with respect to a pseudo-Anosov flow. We also study the interaction of a pseudo-Anosov flow with possible Seifert fibered pieces in the torus decomposition: if the fiber is associated to a periodic orbit of the flow, we produce a standard form for the flow in the piece using Birkhoff annuli. Finally we introduce several new classes of examples, some of which are generalized pseudo-Anosov flows which have one prong singularities. The examples show that the results above in Seifert fibered and solvable manifolds do not apply to one prong pseudo-Anosov flows. In addition we also construct a large new class ...
Turbulent Equipartition Theory of Toroidal Momentum Pinch
Energy Technology Data Exchange (ETDEWEB)
T.S. Hahm, P.H. Diamond, O.D. Gurcan, and G. Rewaldt
2008-01-31
The mode-independet part of magnetic curvature driven turbulent convective (TuroCo) pinch of the angular momentum density [Hahm et al., Phys. Plasmas 14,072302 (2007)] which was originally derived from the gyrokinetic equation, can be interpreted in terms of the turbulent equipartition (TEP) theory. It is shown that the previous results can be obtained from the local conservation of "magnetically weighted angular momentum density," nmi U|| R/B2, and its homogenization due to turbulent flows. It is also demonstrated that the magnetic curvature modification of the parallel acceleration in the nonlinear gyrokinetic equation in the laboratory frame, which was shown to be responsible for the TEP part of the TurCo pinch of angular momentum density in the previous work, is closely related to the Coriolis drift coupling to the perturbed electric field. In addition, the origin of the diffusive flux in the rotating frame is highlighted. Finally, it is illustratd that there should be a difference in scalings between the momentum pinch originated from inherently toroidal effects and that coming from other mechanisms which exist in a simpler geometry.
''Turbulent Equipartition'' Theory of Toroidal Momentum Pinch
International Nuclear Information System (INIS)
The mode-independent part of magnetic curvature driven turbulent convective (TuroCo) pinch of the angular momentum density (Hahm et al., Phys. Plasmas 14,072302 (2007)) which was originally derived from the gyrokinetic equation, can be interpreted in terms of the turbulent equipartition (TEP) theory. It is shown that the previous results can be obtained from the local conservation of 'magnetically weighted angular momentum density', nmi U#parallel# R/B2, and its homogenization due to turbulent flows. It is also demonstrated that the magnetic curvature modification of the parallel acceleration in the nonlinear gyrokinetic equation in the laboratory frame, which was shown to be responsible for the TEP part of the TurCo pinch of angular momentum density in the previous work, is closely related to the Coriolis drift coupling to the perturbed electric field. In addition, the origin of the diffusive flux in the rotating frame is highlighted. Finally, it is illustrated that there should be a difference in scalings between the momentum pinch originated from inherently toroidal effects and that coming from other mechanisms which exist in a simpler geometry.
3D blob dynamics in toroidal geometry
DEFF Research Database (Denmark)
Nielsen, Anders Henry; Reiser, Dirk
In this paper we study the simple case of the dynamics of a density perturbation localized in the edge region of a medium sized tokamak in a full 3D geometry. The 2D evolution of such a perturbation has been studied in details on the low-field side, where the gradient of the magnetic field always...... dynamics in a full 3D tokamak geometry including the edge and SOL region as well. Previous studies with the ATTEMPT code proved that density blobs appear for typical parameters in the TEXTOR tokamak. The code has been prepared for flux driven simulations with detailed control of the blob initial state....... The DIESEL code is an extension of the ESEL code [1]. It solves a simple interchange model in full 3D tokamak geometry, where the toroidal direction is divided into a number of drift planes. On each drift plane the equations are solved in a domain corresponding to the full 2D cross section of the tokamak...
An important step for the ATLAS toroid magnet
2000-01-01
The ATLAS experiment's prototype toroid coil arrives at CERN from the CEA laboratory in Saclay on 6 October. The world's largest superconducting toroid magnet is under construction for the ATLAS experiment. A nine-metre long fully functional prototype coil was delivered to CERN at the beginning of October and has since been undergoing tests in the West Area. Built mainly by companies in France and Italy under the supervision of engineers from the CEA-Saclay laboratory near Paris and Italy's INFN-LASA, the magnet is a crucial step forward in the construction of the ATLAS superconducting magnet system. Unlike any particle detector that has gone before, the ATLAS detector's magnet system consists of a large toroidal system enclosing a small central solenoid. The barrel part of the toroidal system will use eight toroid coils, each a massive 25 metres in length. These will dwarf the largest toroids in the world when ATLAS was designed, which measure about six metres. So the ATLAS collaboration decided to build a...
Spontaneous toroidal flow generation due to negative effective momentum diffusivity
McMillan, Ben F.
2015-02-01
Spontaneous structure formation, and in particular, zonal flows, is observed in a broad range of natural and engineered systems, often arising dynamically as the saturated state of a linear instability. Flows in tokamaks are known to self-organise on small scales, but large scale toroidal flows also arise even when externally applied torques are zero. This has previously been interpreted as the result of small externally imposed breaking of a symmetry. However, we show that for large enough field line pitch, a robust spontaneous symmetry breaking occurs, leading to the generation of strong toroidal flow structures; parameters are typical of Spherical Tokamak discharges with reversed shear profiles. The short wavelength dynamics are qualitatively similar to the growth of poloidal flow structures, and toroidal flow gradients nonlinearly saturate at levels where the shearing rate is comparable to linear growth rate. On long wavelengths, we measure Prandtl numbers of around zero for these systems, in conjunction with the formation of structured toroidal flows, and we show that this is consistent with a model of momentum transport where fluxes act to reinforce small flow gradients: the effective momentum diffusivity is negative. Toroidal flow structures are largely unaffected by collisional damping, so this may allow toroidal bulk flows of order the ion thermal velocity to be maintained with zero momentum input. This phenomenon also provides a mechanism for the generation of localised meso-scale structures like transport barriers.
Plasmas in particle accelerators: adiabatic theories for bunched beams
International Nuclear Information System (INIS)
Three different formalisms for discussing Vlasov's equation for bunched beam problems with anharmonic space charge forces are outlined. These correspond to the use of a drift kinetic equation averaged over random betatron motions; a fluidkinetic adiabatic regime analogous to the theory of Chew, Goldberger, and Low; and an adiabatic hydrodynamic theory
High Fidelity Adiabatic Quantum Computation via Dynamical Decoupling
Quiroz, Gregory
2012-01-01
We introduce high-order dynamical decoupling strategies for open system adiabatic quantum computation. Our numerical results demonstrate that a judicious choice of high-order dynamical decoupling method, in conjunction with an encoding which allows computation to proceed alongside decoupling, can dramatically enhance the fidelity of adiabatic quantum computation in spite of decoherence.
Quantum adiabatic algorithm for factorization and its experimental implementation.
Peng, Xinhua; Liao, Zeyang; Xu, Nanyang; Qin, Gan; Zhou, Xianyi; Suter, Dieter; Du, Jiangfeng
2008-11-28
We propose an adiabatic quantum algorithm capable of factorizing numbers, using fewer qubits than Shor's algorithm. We implement the algorithm in a NMR quantum information processor and experimentally factorize the number 21. In the range that our classical computer could simulate, the quantum adiabatic algorithm works well, providing evidence that the running time of this algorithm scales polynomially with the problem size. PMID:19113467
Teleportation of an Unknown Atomic State via Adiabatic Passage
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
We propose a scheme for teleporting an unknown atomic state via adiabatic passage. Taking advantage of adiabatic passage, the atom has no probability of being excited and thus the atomic spontaneous emission is suppressed.We also show that the fidelity can reach 1 under certain condition.
Examination of the adiabatic approximation in open systems
International Nuclear Information System (INIS)
We examine the notion of the adiabatic approximation in open systems by applying it to closed systems. Our results shows that the notion is equivalent to the standard adiabatic approximation if the systems are initially in eigenstates, and it leads to a more general expression if the systems are in mixed states
A theoretical and experimental study of a novel refrigerant compressor
Eames, I. W.
A refrigerant compressor concept was envisaged consisting of a small scale centrifugal compressor driven by a high frequency induction motor on a common shaft with an impeller supported in aerodynamic bearings. The combination of state-of-the-art compressor, bearing and motor technologies potentially provides refrigerator designers with improved system performance and better compressor reliability with significant reductions in weight and physical size at reduced capital and running costs. A detailed description of the prototype compressor unit is included. The concept is compared with conventional compressor systems, and key areas of research requiring detailed investigation are identified. The following are described and/or evaluated: (1) the results of a literature survey into performance of centrifugal compressors; (2) the electric motor; (3) an investigation into the design of the drive shaft and bearing assemblies; (4) external and internal sources of machine vibration; (5) the manufacture of the prototype compressor unit; (6) testing of the compressor unit; (7) development problems encountered during testing; and (8) a computer simulation study of the behavior of a refrigeration system incorporating the prototype compressor. Aspects of the manufacture considered include surface finishes, tolerancing, heat treatments, and balancing processes.
Peeters, A G; Angioni, C; Strintzi, D
2007-06-29
In this Letter, the influence of the "Coriolis drift" on small scale instabilities in toroidal plasmas is shown to generate a toroidal momentum pinch velocity. Such a pinch results because the Coriolis drift generates a coupling between the density and temperature perturbations on the one hand and the perturbed parallel flow velocity on the other. A simple fluid model is used to highlight the physics mechanism and gyro-kinetic calculations are performed to accurately assess the magnitude of the pinch. The derived pinch velocity leads to a radial gradient of the toroidal velocity profile even in the absence of a torque on the plasma and is predicted to generate a peaking of the toroidal velocity profile similar to the peaking of the density profile. Finally, the pinch also affects the interpretation of current experiments.
Multiplicity features of adiabatic autothermal reactors
Energy Technology Data Exchange (ETDEWEB)
Lovo, M.; Balakotaiah, V. (Houston Univ., TX (United States). Dept. of Chemical Engineering)
1992-01-01
In this paper singularity theory, large activation energy asymptotic, and numerical methods are used to present a comprehensive study of the steady-state multiplicity features of three classical adiabatic autothermal reactor models: tubular reactor with internal heat exchange, tubular reactor with external heat exchange, and the CSTR with external heat exchange. Specifically, the authors derive the exact uniqueness-multiplicity boundary, determine typical cross-sections of the bifurcation set, and classify the different types of bifurcation diagrams of conversion vs. residence time. Asymptotic (limiting) models are used to determine analytical expressions for the uniqueness boundary and the ignition and extinction points. The analytical results are used to present simple, explicit and accurate expressions defining the boundary of the region of autothermal operation in the physical parameter space.
Conformal Symmetries of Adiabatic Modes in Cosmology
Hinterbichler, Kurt; Khoury, Justin
2012-01-01
We remark on the existence of non-linearly realized conformal symmetries for scalar adiabatic perturbations in cosmology. These conformal symmetries are present for any cosmological background, beyond any slow-roll or quasi-de Sitter approximation. The dilatation transformation shifts the curvature perturbation by a constant, and corresponds to the well-known symmetry under spatial rescaling. We argue that the scalar sector is also invariant under special conformal transformations, which shift the curvature perturbation by a term linear in the spatial coordinates. We discuss whether these conformal symmetries can be extended to include tensor perturbations. Tensor modes introduce their own set of non-linearly realized symmetries. We identify an infinite set of large gauge transformations which maintain the transverse, traceless gauge condition, while shifting the tensor mode non-trivially.
Adiabatic theory for anisotropic cold molecule collisions
International Nuclear Information System (INIS)
We developed an adiabatic theory for cold anisotropic collisions between slow atoms and cold molecules. It enables us to investigate the importance of the couplings between the projection states of the rotational motion of the atom about the molecular axis of the diatom. We tested our theory using the recent results from the Penning ionization reaction experiment 4He(1s2s 3S) + HD(1s2) → 4He(1s2) + HD+(1s) + e− [Lavert-Ofir et al., Nat. Chem. 6, 332 (2014)] and demonstrated that the couplings have strong effect on positions of shape resonances. The theory we derived provides cross sections which are in a very good agreement with the experimental findings
Adiabatic theory for anisotropic cold molecule collisions.
Pawlak, Mariusz; Shagam, Yuval; Narevicius, Edvardas; Moiseyev, Nimrod
2015-08-21
We developed an adiabatic theory for cold anisotropic collisions between slow atoms and cold molecules. It enables us to investigate the importance of the couplings between the projection states of the rotational motion of the atom about the molecular axis of the diatom. We tested our theory using the recent results from the Penning ionization reaction experiment (4)He(1s2s (3)S) + HD(1s(2)) → (4)He(1s(2)) + HD(+)(1s) + e(-) [Lavert-Ofir et al., Nat. Chem. 6, 332 (2014)] and demonstrated that the couplings have strong effect on positions of shape resonances. The theory we derived provides cross sections which are in a very good agreement with the experimental findings. PMID:26298122
Adiabatic theory for anisotropic cold molecule collisions
Energy Technology Data Exchange (ETDEWEB)
Pawlak, Mariusz [Schulich Faculty of Chemistry, Technion–Israel Institute of Technology, Haifa 32000 (Israel); Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Toruń (Poland); Shagam, Yuval; Narevicius, Edvardas [Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100 (Israel); Moiseyev, Nimrod [Schulich Faculty of Chemistry, Technion–Israel Institute of Technology, Haifa 32000 (Israel); Faculty of Physics, Technion–Israel Institute of Technology, Haifa 32000 (Israel)
2015-08-21
We developed an adiabatic theory for cold anisotropic collisions between slow atoms and cold molecules. It enables us to investigate the importance of the couplings between the projection states of the rotational motion of the atom about the molecular axis of the diatom. We tested our theory using the recent results from the Penning ionization reaction experiment {sup 4}He(1s2s {sup 3}S) + HD(1s{sup 2}) → {sup 4}He(1s{sup 2}) + HD{sup +}(1s) + e{sup −} [Lavert-Ofir et al., Nat. Chem. 6, 332 (2014)] and demonstrated that the couplings have strong effect on positions of shape resonances. The theory we derived provides cross sections which are in a very good agreement with the experimental findings.
Number Partitioning via Quantum Adiabatic Computation
Smelyanskiy, Vadim N.; Toussaint, Udo; Clancy, Daniel (Technical Monitor)
2002-01-01
We study both analytically and numerically the complexity of the adiabatic quantum evolution algorithm applied to random instances of combinatorial optimization problems. We use as an example the NP-complete set partition problem and obtain an asymptotic expression for the minimal gap separating the ground and exited states of a system during the execution of the algorithm. We show that for computationally hard problem instances the size of the minimal gap scales exponentially with the problem size. This result is in qualitative agreement with the direct numerical simulation of the algorithm for small instances of the set partition problem. We describe the statistical properties of the optimization problem that are responsible for the exponential behavior of the algorithm.
Parametric Erosion Investigation: Propellant Adiabatic Flame Temperature
Directory of Open Access Journals (Sweden)
P. J. Conroy
2002-01-01
Full Text Available The influence of quasi-independent parameters and their potential influence on erosion in guns have been investigated. Specifically, the effects of flame temperature and the effect of assuming that the Lewis number (ratio of mass-to-heat transport to the surface, Le = 1, has been examined. The adiabatic flame temperature for a propellant was reduced by the addition of a diluent from a high temperature of 3843 K (similar to that of M9 down to 3004 K, which is near the value for M30A1 propellant. Mass fractions of critical species at the surface with and without the assumption of Le = 1 are presented, demonstrating that certain species preferentially reach the surface providing varied conditions for the surface reactions. The results for gun tube bore surface regression qualitatively agree with previous studies and with current experimental data.
An Integrated Development Environment for Adiabatic Quantum Programming
Energy Technology Data Exchange (ETDEWEB)
Humble, Travis S [ORNL; McCaskey, Alex [ORNL; Bennink, Ryan S [ORNL; Billings, Jay Jay [ORNL; D' Azevedo, Eduardo [ORNL; Sullivan, Blair D [ORNL; Klymko, Christine F [ORNL; Seddiqi, Hadayat [ORNL
2014-01-01
Adiabatic quantum computing is a promising route to the computational power afforded by quantum information processing. The recent availability of adiabatic hardware raises the question of how well quantum programs perform. Benchmarking behavior is challenging since the multiple steps to synthesize an adiabatic quantum program are highly tunable. We present an adiabatic quantum programming environment called JADE that provides control over all the steps taken during program development. JADE captures the workflow needed to rigorously benchmark performance while also allowing a variety of problem types, programming techniques, and processor configurations. We have also integrated JADE with a quantum simulation engine that enables program profiling using numerical calculation. The computational engine supports plug-ins for simulation methodologies tailored to various metrics and computing resources. We present the design, integration, and deployment of JADE and discuss its use for benchmarking adiabatic quantum programs.
Adiabatic logic future trend and system level perspective
Teichmann, Philip
2012-01-01
Adiabatic logic is a potential successor for static CMOS circuit design when it comes to ultra-low-power energy consumption. Future development like the evolutionary shrinking of the minimum feature size as well as revolutionary novel transistor concepts will change the gate level savings gained by adiabatic logic. In addition, the impact of worsening degradation effects has to be considered in the design of adiabatic circuits. The impact of the technology trends on the figures of merit of adiabatic logic, energy saving potential and optimum operating frequency, are investigated, as well as degradation related issues. Adiabatic logic benefits from future devices, is not susceptible to Hot Carrier Injection, and shows less impact of Bias Temperature Instability than static CMOS circuits. Major interest also lies on the efficient generation of the applied power-clock signal. This oscillating power supply can be used to save energy in short idle times by disconnecting circuits. An efficient way to generate the p...
How detrimental is decoherence in adiabatic quantum computation?
Albash, Tameem
2015-01-01
Recent experiments with increasingly larger numbers of qubits have sparked renewed interest in adiabatic quantum computation, and in particular quantum annealing. A central question that is repeatedly asked is whether quantum features of the evolution can survive over the long time-scales used for quantum annealing relative to standard measures of the decoherence time. We reconsider the role of decoherence in adiabatic quantum computation and quantum annealing using the adiabatic quantum master equation formalism. We restrict ourselves to the weak-coupling and singular-coupling limits, which correspond to decoherence in the energy eigenbasis and in the computational basis, respectively. We demonstrate that decoherence in the instantaneous energy eigenbasis does not necessarily detrimentally affect adiabatic quantum computation, and in particular that a short single-qubit $T_2$ time need not imply adverse consequences for the success of the quantum adiabatic algorithm. We further demonstrate that boundary canc...
Adiabatic Rearrangement of Hollow PV Towers
Directory of Open Access Journals (Sweden)
Eric A Hendricks
2010-10-01
Full Text Available Diabatic heating from deep moist convection in the hurricane eyewall produces a towering annular structure of elevated potential vorticity (PV. This structure has been referred to as a hollow PV tower. The sign reversal of the radial gradient of PV satisfies the Charney-Stern necessary condition for combined barotropic-baroclinic instability. For thin enough annular structures, small perturbations grow exponentially, extract energy from the mean flow, and lead to hollow tower breakdown, with significant vortex structural and intensity change. The three-dimensional adiabatic rearrangements of two prototypical hurricane-like hollow PV towers (one thick and one thin are examined in an idealized framework. For both hollow towers, dynamic instability causes air parcels with high PV to be mixed into the eye preferentially at lower levels, where unstable PV wave growth rates are the largest. Little or no mixing is found to occur at upper levels. The mixing at lower and middle levels is most rapid for the breakdown of the thin hollow tower, consistent with previous barotropic results. For both hollow towers, this advective rearrangement of PV affects the tropical cyclone structure and intensity in a number of ways. First, the minimum central pressure and maximum azimuthal mean velocity simultaneously decrease, consistent with previous barotropic results. Secondly, isosurfaces of absolute angular momentum preferentially shift inward at low levels, implying an adiabatic mechanism by which hurricane eyewall tilt can form. Thirdly, a PV bridge, similar to that previously found in full-physics hurricane simulations, develops as a result of mixing at the isentropic levels where unstable PV waves grow most rapidly. Finally, the balanced mass field resulting from the PV rearrangement is warmer in the eye between 900 and 700 hPa. The location of this warming is consistent with observed warm anomalies in the eye, indicating that in certain instances the hurricane
Power spectra in the eikonal approximation with adiabatic and non-adiabatic modes
Bernardeau, Francis; Vernizzi, Filippo
2012-01-01
We use the so-called eikonal approximation, recently introduced in the context of cosmological perturbation theory, to compute power spectra for multi-component fluids. We demonstrate that, at any given order in standard perturbation theory, multi-point power spectra do not depend on the large-scale adiabatic modes. Moreover, we employ perturbation theories to decipher how non-adiabatic modes, such as a relative velocity between two different components, damp the small-scale matter power spectrum, a mechanism recently described in the literature. In particular, we do an explicit calculation at 1-loop order of this effect. While the 1-loop result eventually breaks down, we show how the damping effect can be fully captured by the help of the eikonal approximation. A relative velocity not only induces mode damping but also creates large-scale anisotropic modulations of the matter power spectrum amplitude. We illustrate this for the Local Group environment.
Non-adiabatic molecular dynamics with complex quantum trajectories. II. The adiabatic representation
Energy Technology Data Exchange (ETDEWEB)
Zamstein, Noa; Tannor, David J. [Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100 (Israel)
2012-12-14
We present a complex quantum trajectory method for treating non-adiabatic dynamics. Each trajectory evolves classically on a single electronic surface but with complex position and momentum. The equations of motion are derived directly from the time-dependent Schroedinger equation, and the population exchange arises naturally from amplitude-transfer terms. In this paper the equations of motion are derived in the adiabatic representation to complement our work in the diabatic representation [N. Zamstein and D. J. Tannor, J. Chem. Phys. 137, 22A517 (2012)]. We apply our method to two benchmark models introduced by John Tully [J. Chem. Phys. 93, 1061 (1990)], and get very good agreement with converged quantum-mechanical calculations. Specifically, we show that decoherence (spatial separation of wavepackets on different surfaces) is already contained in the equations of motion and does not require ad hoc augmentation.
Non-adiabatic molecular dynamics with complex quantum trajectories. II. The adiabatic representation
International Nuclear Information System (INIS)
We present a complex quantum trajectory method for treating non-adiabatic dynamics. Each trajectory evolves classically on a single electronic surface but with complex position and momentum. The equations of motion are derived directly from the time-dependent Schrödinger equation, and the population exchange arises naturally from amplitude-transfer terms. In this paper the equations of motion are derived in the adiabatic representation to complement our work in the diabatic representation [N. Zamstein and D. J. Tannor, J. Chem. Phys. 137, 22A517 (2012)]. We apply our method to two benchmark models introduced by John Tully [J. Chem. Phys. 93, 1061 (1990)], and get very good agreement with converged quantum-mechanical calculations. Specifically, we show that decoherence (spatial separation of wavepackets on different surfaces) is already contained in the equations of motion and does not require ad hoc augmentation.
Kinetic characteristic for a synchronal rotary compressor
Institute of Scientific and Technical Information of China (English)
Qu Zongchang; Feng Jianmei; Zhou Hui; Yang Hua
2007-01-01
An angular speed, acceleration and tangential leakage of a synchronal rotary compressor in which both bladed rotor and a cylinder are discussed. The calculation formulae of revolving speed of cylinder and relative speed between the cylinder and bladed rotor are deduced detailedly in this paper. The variation of tangential speed and cylinder acceleration with angular position is investigated for a complete cycle. And some key parameters affected the relative speed are found out, viz, the relative speed depends on the radius of the cylinder and rotary speed of the axis, and the ratio of the cylinder to bladed rotor has not too much influence. It is the theoretic basis of designing and optimizing of structure characteristic of a synchronal rotary compressor. Also a computing formula of leakage related with rotary speed is deduced. It could supply
High stability design for new centrifugal compressor
Kanki, H.; Katayama, K.; Morii, S.; Mouri, Y.; Umemura, S.; Ozawa, U.; Oda, T.
1989-01-01
It is essential that high-performance centrifugal compressors be free of subsynchronous vibrations. A new high-performance centrifugal compressor has been developed by applying the latest rotordynamics knowledge and design techniques: (1) To improve the system damping, a specially designed oil film seal was developed. This seal attained a damping ratio three times that of the conventional design. The oil film seal contains a special damper ring in the seal cartridge. (2) To reduce the destabilizing effect of the labyrinth seal, a special swirl canceler (anti-swirl nozzle) was applied to the balance piston seal. (3) To confirm the system damping margin, the dynamic simulation rotor model test and the full load test applied the vibration exciting test in actual load conditions.
Research on Flow Characteristics of Supercritical CO2 Axial Compressor Blades by CFD Analysis
Takagi, Kazuhisa; Muto, Yasushi; Ishizuka, Takao; Kikura, Hiroshige; Aritomi, Masanori
A supercritical CO2 gas turbine of 20MPa is suitable to couple with the Na-cooled fast reactor since Na - CO2 reaction is mild at the outlet temperature of 800K, the cycle thermal efficiency is relatively high and the size of CO2 gas turbine is very compact. In this gas turbine cycle, a compressor operates near the critical point. The property of CO2 and then the behavior of compressible flow near the critical point changes very sharply. So far, such a behavior is not examined sufficiently. Then, it is important to clarify compressible flow near the critical point. In this paper, an aerodynamic design of the axial supercritical CO2 compressor for this system has been carried out based on the existing aerodynamic design method of Cohen1). The cycle design point was selected to achieve the maximum cycle thermal efficiency of 43.8%. For this point, the compressor design conditions were determined. They are a mass flow rate of 2035kg/s, an inlet temperature of 308K, an inlet static pressure of 8.26MPa, an outlet static pressure of 20.6MPa and a rotational speed of 3600rpm. The mean radius was constant through axial direction. The design point was determined so as to keep the diffusion factor and blade stress within the allowable limits. Number of stages and an expected adiabatic efficiency was 14 and 87%, respectively. CFD analyses by FLUENT have been done for this compressor blade. The blade model consists of one set of a guide vane, a rotor blade and a stator blade. The analyses were conducted under the assumption both of the real gas properties and also of the modified ideal gas properties. Using the real gas properties, analysis was conducted for the 14th blade, whose condition is remote from the critical point and the possibility of divergence is very small. Then, the analyses were conducted for the blade whose conditions are nearer to the critical point. Gradually, divergence of calculation was encountered. Convergence was relatively easy for the modified ideal
Surge and stall in centrifugal compressors
Vandenbraembussche, R.
Surge and stall are defined, and experimental and theoretical investigations of surge in compressors, stall in vaned flow passages, and stall in vaneless flow passages are reviewed. Ways to delay surge and stall are outlined. Actions to influence the surge limit during design or to correct for an eventual misprediction often decrease efficiency when the range has to be increased. The main action to avoid surge and stall is a safe design of impeller and diffuser and a correct matching of both components.
Risk Based Maintenance for Compressor Systems
Marquesin De Oliveira, Nathalie
2015-01-01
This thesis reviewed part of the maintenance activities in a compressor system using the risk based maintenance philosophy. The goal was to verify if a contribution could be made to the maintenance plan of the system. The risk based maintenance philosophy is applied according to the recommendations in NORSOK Z-008. A reliability model is proposed to verify the impact of the new maintenance approach and to make better informed decisions in the maintenance management process. The model used...
Analysis and developpment of a Turbivo compressor for MRV applications
Ksayer, Elias Boulawz
2010-01-01
The mechanical vapor recompression is an efficient process to decrease energy consumption of drying processes. In order to use the mechanical vapor recompression (MVR) in residential clothe dryers, the volumetric Turbivo technology is used to design a dry water vapor compressor. The Turbivo volumetric machine is composed mainly of a rotor with one blade, a stator, and a mobile oscillating thrust. The advantages of Turbivo(R) technology are the absence of contact between rotor and stator as well as the oil-free operation. A model of the Turbivo compressor, including kinematic, dynamic, and thermodynamic analysis is presented. The compressor internal tightness is ensured by a surface treatment of the compressor components. Using the model, a water vapor Turbivo compressor of 12m3/h and compression ratio of 5 has been sized and realized. The compressor prototype will be tested on a dedicated test bench to characterize its volumetric and isentropic efficiencies.
Object-oriented Technology for Compressor Simulation
Drummond, C. K.; Follen, G. J.; Cannon, M. R.
1994-01-01
An object-oriented basis for interdisciplinary compressor simulation can, in principle, overcome several barriers associated with the traditional structured (procedural) development approach. This paper presents the results of a research effort with the objective to explore the repercussions on design, analysis, and implementation of a compressor model in an object oriented (OO) language, and to examine the ability of the OO system design to accommodate computational fluid dynamics (CFD) code for compressor performance prediction. Three fundamental results are that: (1) the selection of the object oriented language is not the central issue; enhanced (interdisciplinary) analysis capability derives from a broader focus on object-oriented technology; (2) object-oriented designs will produce more effective and reusable computer programs when the technology is applied to issues involving complex system inter-relationships (more so than when addressing the complex physics of an isolated discipline); and (3) the concept of disposable prototypes is effective for exploratory research programs, but this requires organizations to have a commensurate long-term perspective. This work also suggests that interdisciplinary simulation can be effectively accomplished (over several levels of fidelity) with a mixed language treatment (i.e., FORTRAN-C++), reinforcing the notion the OO technology implementation into simulations is a 'journey' in which the syntax can, by design, continuously evolve.
Numerical simulation of piston leakage over hermetic reciprocating compressors behavior.
Rigola Serrano, Joaquim; Pérez Segarra, Carlos David; Oliva Llena, Asensio
2009-01-01
Instantaneous flow leakage between piston and cylinder is numerically evaluated. Reynolds equation is solved to calculate the pressure leakage distribution through the piston in the compressor. Piston movement inside the cylinder is simulated from kinematic analysis of the connecting rod mechanical system and the respective force balances. An updated version of this model is here presented for different working range compressors and fluid refrigerants compressor chamber pressures distribution...
Visualization of Flow in Scroll Compressor by Radiography
Chikano, Masatsugu; SHIMIZU Hayato; Tsuchiya, Takeshi; Tojo, Kenji
2012-01-01
Saving energy and resources in the air conditioning industry is required in order to protect the global environment. To save resources, miniaturization of the compressor in air conditioners is necessary. This miniaturization will increase the oil circulation rate (OCR) of the compressor because the oil separation space will be reduced. To improve the oil separation efficiency, it is necessary to understand the appearance of the flow of oil and refrigerant in the compressor chamber. This paper...
Performance and Operating Characteristics of a Novel Rotating Spool Compressor
Orosz, Joe; Kemp, Greg; Bradshaw, Craig; Eckhard A. Groll
2012-01-01
The basic mechanism of the novel rotary spool compressor has been described previously by Kemp et al. (2008, 2010). The device combines various aspects of rotary and reciprocating devices currently well understood to achieve high efficiency at a low manufacturing cost. A dimensionless variable, the Zsoro number, is developed which represents the ratio of the geometric configuration of the compressor relative to the potential friction components of the compressor. This number allows for rapid ...
Seal Mechanism of Tip Seal in Scroll Compressor
Fukuta, Mitsuhiro; Ogi, Daisuke; Motozawa, Masaaki; Yanagisawa, Tadashi; Iwanami, Shigeki; Hotta, Tadashi
2014-01-01
Scroll compressors are widely used in room air conditioning cycles, package air conditioning cycles, refrigeration, water heater and automobile air conditioning cycles as well as air compressors, helium compressors and vacuum pump. There are two main leakage paths in a compression chamber formed by a fixed scroll and an orbiting scroll. One is the leakage path through a radial clearance between the wraps of fixed and orbiting scroll. The leakage through the radial clearance is prevented by pr...
Real-time trend monitoring of gas compressor stations
Energy Technology Data Exchange (ETDEWEB)
Van Hardeveld, T. (Nova, an Alberta Corp., AB (Canada))
1991-02-01
The authors' company has developed a machinery health monitoring system (MHealth) for short-term and long-term historical trending and analysis of data from its 40 gas compressor stations. The author discusses the benefits of real-time trending in troubleshooting operations, in preventative maintenance scheduling and cites specific applications in the startup operations of several new gas compressor/centrifugal compressor units.
IC ENGINE SUPERCHARGING AND EXHAUST GAS RECIRCULATION USING JET COMPRESSOR
Adhimoulame Kalaisselvane; Natarajan Alagumurthy; Krishnaraj Palaniradja; G Selvaraj Gunasegarane
2010-01-01
Supercharging is a process which is used to improve the performance of an engine by increasing the specific power output whereas exhaust gas recirculation reduces the NOx produced by engine because of supercharging. In a conventional engine, supercharger functions as a compressor for the forced induction of the charge taking mechanical power from the engine crankshaft. In this study, supercharging is achieved using a jet compressor. In the jet compressor, the exhaust gas is used as the motive...
Centrifugal Compressor Load Sharing with the use of MPC
Overvåg, Thomas Ferstad
2013-01-01
The work presented in this thesis examines the possibilities of having compressors running in an optimal manner which can result in energy savings. This research looks at how a compressor operates and the problems which can occur when connecting several machines, both in series and parallel. It is mainly focused on using Model Predictive Control (MPC), as a setup for controlling each compressor to a fixed operating point on the characteristic with relation to mass flow and pressure. Constrain...
On the Development of an Efficient Regenerative Compressor
Griffini, D.; Salvadori, S.; Carnevale, M.; A. Cappelletti; Ottanelli, L.; Martelli, F.
2015-01-01
Regenerative compressors are attractive machines used in several industrial processes. Their main characteristic is the highly three-dimensional development of the flow. Consequently, usual approach for axial or centrifugal compressors design are not an affordable strategy. The analysis of the rotor/stator coupling is the main issue in the design of regenerative compressors because of the vane-less nature of the stator and the characteristic trajectory of the flow. This paper describes the de...
A Valve Design Methodology For Improved Reciprocating Compressor Performance
Bhakta, Aditya; Dhar, Sandeep; Bahadur, Vaibhav; Angadi, Shruti; Dey, Subhrajit
2012-01-01
The current work directly relates valve dynamics to the compressor energy efficiency. Majority of the previous studies have focused on reducing pressure losses due to valve geometry, towards improved compressor performance. On a complimentary note, analyzing the valve ‘flutter’ leads to a holistic valve development methodology. Traditionally, pressure actuated reed valves have been used in reciprocating hermetic compressors on the suction and discharge ports. A characteristic of these valve ...
Study on the Oil Supply System for Rotary Compressors
Ito, Takahide; Kobayashi, Hiroyuki; Fujitani, Makoto; Murata, Nobuo
Research has been undertaken to clarify the shaft oil pump mechanisms and oil supply network systems for rotary compressors. Numerical expressions were developed for each part of the rotary compressor,(such as drive shaft,oil pump and journal bearing grooves)in order to confirm that the calculated values agree with the experimental results. Finally,a computer program has been developed to evaluate the oil supply system performance under steady conditions for rotary compressors.
Experiments during flow boiling of a R22 drop-in: R422D adiabatic pressure gradients
Energy Technology Data Exchange (ETDEWEB)
Rosato, A.; Mauro, A.W.; Mastrullo, R. [D.E.TE.C., Facolta di Ingegneria, Universita degli Studi di Napoli Federico II, p.le Tecchio 80, 80125 Napoli (Italy); Vanoli, G.P. [Dipartimento di Ingegneria, Universita degli Studi del Sannio, corso Garibaldi 107, Palazzo dell' Aquila Bosco Lucarelli, 82100 Benevento (Italy)
2009-10-15
R22, the HCFC most widely used in refrigeration and air-conditioning systems in the last years, is phasing-out. R422D, a zero ozone-depleting mixture of R125, R134a and R600a (65.1%/31.5%/3.4% by weight, respectively), has been recently proposed as a drop-in substitute. For energy consumption calculations and temperature control, it is of primary importance to estimate operating conditions after substitution. To determine pressure drop in the evaporator and piping line to the compressor, in this paper the experimental adiabatic pressure gradients during flow boiling of R422D are reported for a circular smooth horizontal tube (3.00 mm inner radius) in a range of operating conditions of interest for dry-expansion evaporators. The data are used to establish the best predictive method for calculations and its accuracy: the Moreno-Quiben and Thome method provided the best predictions for the whole database and also for the segregated data in the annular flow regime. Finally, the experimental data have been compared with the adiabatic pressure gradients of both R22 and its much used alternative R407C available in the literature. (author)
Small variable speed hermetic reciprocating compressors for domestic refrigerators
DEFF Research Database (Denmark)
Rasmussen, Bjarne D.
1996-01-01
This paper contains both a theoretical and experimental investigation of some of the fundamental characteristics of a smal variable speed hermetic reciprocating compressor intended for application in domestic refrigeration. The results of a previously published simulation model for variable speed...... compressors are compared with experimental results obtained in a compressor test bench. The influence of speed on compressor performance is discussed with focus on valve modelling and internal thermal phenomena. Further plans for development and validation of the model as well as experimental investigations...
Nam, Donglim; Lee, Poyoung; Lee, Geonho; Kwon, Yunki; Lee, Jinho
2014-01-01
The main roles of the oil in scroll compressor are to lubricate the friction parts, and to reduce the compressor driving power and to improve the durability of the compressor consequently. However, it has another side that could make decrease the efficiency of the heat exchanger and whole air-conditioning system. In the case of compressor, if the oil is charged too much, the compressor driving power will be increased and the compressor overall efficiency will be decreased. Therefore, the init...
Pookongchai Kritsada; Nakornrat Prasit; Sookananta Bongkoj; Buasri Panhathai
2015-01-01
This paper presents method to detect air leakage of an air conditioning compressor using image processing techniques. Quality of air conditioning compressor should not have air leakage. To test an air conditioning compressor leak, air is pumped into a compressor and then submerged into the water tank. If air bubble occurs at surface of the air conditioning compressor, that leakage compressor must be returned for maintenance. In this work a new method to detect leakage and search leakage point...
Physics models in the toroidal transport code PROCTR
Energy Technology Data Exchange (ETDEWEB)
Howe, H.C.
1990-08-01
The physics models that are contained in the toroidal transport code PROCTR are described in detail. Time- and space-dependent models are included for the plasma hydrogenic-ion, helium, and impurity densities, the electron and ion temperatures, the toroidal rotation velocity, and the toroidal current profile. Time- and depth-dependent models for the trapped and mobile hydrogenic particle concentrations in the wall and a time-dependent point model for the number of particles in the limiter are also included. Time-dependent models for neutral particle transport, neutral beam deposition and thermalization, fusion heating, impurity radiation, pellet injection, and the radial electric potential are included and recalculated periodically as the time-dependent models evolve. The plasma solution is obtained either in simple flux coordinates, where the radial shift of each elliptical, toroidal flux surface is included to maintain an approximate pressure equilibrium, or in general three-dimensional torsatron coordinates represented by series of helical harmonics. The detailed coupling of the plasma, scrape-off layer, limiter, and wall models through the neutral transport model makes PROCTR especially suited for modeling of recycling and particle control in toroidal plasmas. The model may also be used in a steady-state profile analysis mode for studying energy and particle balances starting with measured plasma profiles.
Toroidal linear force-free magnetic fields with axial symmetry
Vandas, M.; Romashets, E.
2016-01-01
Aims: Interplanetary magnetic flux ropes are often described as linear force-free fields. To account for their curvature, toroidal configurations must be used. The aim is to find an analytic description of a linear force-free magnetic field of the toroidal geometry in which the cross section of flux ropes can be controlled. Methods: The solution is found as a superposition of fields given by linear force-free cylinders tangential to a generating toroid. The cylindrical field is expressed in a series of terms that are not all cylindrically symmetric. Results: We found the general form of a toroidal linear force-free magnetic field. The field is azimuthally symmetric with respect to the torus axis. It depends on a set of coefficients that enables controlling the flux rope shape (cross section) to some extent. By varying the coefficients, flux ropes with circular and elliptic cross sections were constructed. Numerical comparison suggests that the simple analytic formula for calculating the helicity in toroidal flux ropes of the circular cross section can be used for flux ropes with elliptic cross sections if the minor radius in the formula is set to the geometric mean of the semi-axes of the elliptic cross section.
Physics models in the toroidal transport code PROCTR
International Nuclear Information System (INIS)
The physics models that are contained in the toroidal transport code PROCTR are described in detail. Time- and space-dependent models are included for the plasma hydrogenic-ion, helium, and impurity densities, the electron and ion temperatures, the toroidal rotation velocity, and the toroidal current profile. Time- and depth-dependent models for the trapped and mobile hydrogenic particle concentrations in the wall and a time-dependent point model for the number of particles in the limiter are also included. Time-dependent models for neutral particle transport, neutral beam deposition and thermalization, fusion heating, impurity radiation, pellet injection, and the radial electric potential are included and recalculated periodically as the time-dependent models evolve. The plasma solution is obtained either in simple flux coordinates, where the radial shift of each elliptical, toroidal flux surface is included to maintain an approximate pressure equilibrium, or in general three-dimensional torsatron coordinates represented by series of helical harmonics. The detailed coupling of the plasma, scrape-off layer, limiter, and wall models through the neutral transport model makes PROCTR especially suited for modeling of recycling and particle control in toroidal plasmas. The model may also be used in a steady-state profile analysis mode for studying energy and particle balances starting with measured plasma profiles
Experimental implementation of an adiabatic quantum optimization algorithm
Steffen, M; Hogg, T; Breyta, G; Chuang, I; Steffen, Matthias; Dam, Wim van; Hogg, Tad; Breyta, Greg; Chuang, Isaac
2003-01-01
We report the realization of a nuclear magnetic resonance computer with three quantum bits that simulates an adiabatic quantum optimization algorithm. Adiabatic quantum algorithms offer new insight into how quantum resources can be used to solve hard problems. This experiment uses a particularly well suited three quantum bit molecule and was made possible by introducing a technique that encodes general instances of the given optimization problem into an easily applicable Hamiltonian. Our results indicate an optimal run time of the adiabatic algorithm that agrees well with the prediction of a simple decoherence model.
A note on the geometric phase in adiabatic approximation
Tong, D M; Kwek, L C; Oh, C H
2004-01-01
It is widely held that the Berry phase of a quantum system is the geometric phase in adiabatic approximation. However, Pati and Rajagopal recently claimed that the Berry phase vanishes under strict adiabatic evolution. In this note, we reexamine and address this issue. In particular, we show that the use of the adiabatic theorem does not lead to this inconsistency. We also examine the difference between the Berry phase and the exact geometric phase. Here we find that the Berry phase may differ appreciably from the exact geometric phase if the evolution time is large enough.
Approximability of optimization problems through adiabatic quantum computation
Cruz-Santos, William
2014-01-01
The adiabatic quantum computation (AQC) is based on the adiabatic theorem to approximate solutions of the Schrödinger equation. The design of an AQC algorithm involves the construction of a Hamiltonian that describes the behavior of the quantum system. This Hamiltonian is expressed as a linear interpolation of an initial Hamiltonian whose ground state is easy to compute, and a final Hamiltonian whose ground state corresponds to the solution of a given combinatorial optimization problem. The adiabatic theorem asserts that if the time evolution of a quantum system described by a Hamiltonian is l
Adiabatic Pair Creation in Heavy Ion and Laser Fields
Pickl, P; Pickl, Peter; Duerr, Detlef
2006-01-01
The planned generation of lasers and heavy ion colliders renews the hope to see electron-positron pair creation in strong classical fields (so called spontaneous pair creation). This adiabatic relativistic effect has however not been described in a unified manner. We discuss here the theory of adiabatic pair creation yielding the momentum distribution of scattered pairs in overcritical fields. Our conclusion about the possibility of adiabatic pair creation is much more positive than earlier predictions for laser fields and most importantly gives priority to optical before X-ray lasers.
Constraints on the Adiabatic Temperature Change in Magnetocaloric Materials
DEFF Research Database (Denmark)
Nielsen, Kaspar Kirstein; Bahl, Christian Robert Haffenden; Smith, Anders
2010-01-01
The thermodynamics of the magnetocaloric effect implies constraints on the allowed variation in the adiabatic temperature change for a magnetocaloric material. An inequality for the derivative of the adiabatic temperature change with respect to temperature is derived for both first- and second......-order materials. For materials with a continuous adiabatic temperature change as a function of temperature, this inequality is shown to hold for all temperatures. However, discontinuous materials may violate the inequality. We compare our results with measured results in the literature and discuss...
Adiabatic control of atomic dressed states for transport and sensing
Cooper, N. R.; Rey, A. M.
2015-08-01
We describe forms of adiabatic transport that arise for dressed-state atoms in optical lattices. Focusing on the limit of weak tunnel-coupling between nearest-neighbor lattice sites, we explain how adiabatic variation of optical dressing allows control of atomic motion between lattice sites: allowing adiabatic particle transport in a direction that depends on the internal state, and force measurements via spectroscopic preparation and readout. For uniformly filled bands these systems display topologically quantized particle transport. An implementation of the dressing scheme using optical transitions in alkaline-earth atoms is discussed as well as its favorable features for precise force sensing.
Optical toroidal dipolar response by an asymmetric double-bar metamaterial
Dong, Zheng-Gao; Rho, Junsuk; Li, Jia-Qi; Lu, Changgui; Yin, Xiaobo; Zhang, X; 10.1063/1.4757613
2012-01-01
We demonstrate that the toroidal dipolar response can be realized in the optical regime by designing a feasible nanostructured metamaterial, comprising asymmetric double-bar magnetic resonators assembled into a toroid-like configuration. It is confirmed numerically that an optical toroidal dipolar moment dominates over other moments. This response is characterized by a strong confinement of an E-field component at the toroid center, oriented perpendicular to the H-vortex plane. The resonance-enhanced optical toroidal response can provide an experimental avenue for various interesting optical phenomena associated with the elusive toroidal moment.
On the persistence of adiabatic shear bands
Directory of Open Access Journals (Sweden)
Bassim M.N.
2012-08-01
Full Text Available It is generally agreed that the initiation and development of adiabatic shear bands (ASBs are manifestations of damage in metallic materials subjected to high strain rates and large strains as those due to impact in a Hopkinson Bar system. Models for evolution of these bands have been described in the literature. One question that has not received attention is how persistent these bands are and whether their presence and effect can be reversed or eliminated by using a process of thermal (heat treatment or thermo-mechanical treatment that would relieve the material from the high strain associated with ASBs and their role as precursors to crack initiation and subsequent failure. Since ASBs are more prevalent and more defined in BCC metals including steels, a study was conducted to investigate the best conditions of generating ASBs in a heat treatable steel, followed by determining the best conditions for heat treatment of specimens already damaged by the presence of ASBs in order to relieve the strains due to ASBs and restore the material to an apparent microstructure without the “scars” due to the previous presence of ASBs. It was found that heat treatment achieves the curing from ASBs. This presentation documents the process undertaken to achieve this objective.
Design of the PIXIE Adiabatic Demagnetization Refrigerators
Shirron, Peter J.; Kimball, Mark Oliver; Fixsen, Dale J.; Kogut, Alan J.; Li, Xiaoyi; DiPirro, Michael
2012-01-01
The Primordial Inflation Explorer (PIXIE) is a proposed mission to densely map the polarization of the cosmic microwave background. It will operate in a scanning mode from a sun-synchronous orbit, using low temperature detectors (at 0.1 K) and located inside a teslescope that is cooled to approximately 2.73 K - to match the background temperature. A mechanical cryocooler operating at 4.5 K establishes a low base temperature from which two adiabatic demagnetization refrigerator (ADR) assemblies will cool the telescope and detectors. To achieve continuous scanning capability, the ADRs must operate continuously. Complicating the design are two factors: 1) the need to systematically vary the temperature of various telescope components in order to separate the small polarization signal variations from those that may arise from temperature drifts and changing gradients within the telescope, and 2) the orbital and monthly variations in lunar irradiance into the telescope barrels. These factors require the telescope ADR to reject quasi-continuous heat loads of 2-3 millwatts, while maintaining a peak heat reject rate of less than 12 milliwatts. The detector heat load at 0.1 K is comparatively small at 1-2 microwatts. This paper will describe the 3-stage and 2-stage continuous ADRs that will be used to meet the cooling power and temperature stability requirements of the PIXIE detectors and telescope.
Graph isomorphism and adiabatic quantum computing
Gaitan, Frank; Clark, Lane
2014-03-01
In the Graph Isomorphism (GI) problem two N-vertex graphs G and G' are given and the task is to determine whether there exists a permutation of the vertices of G that preserves adjacency and maps G --> G'. If yes (no), then G and G' are said to be isomorphic (non-isomorphic). The GI problem is an important problem in computer science and is thought to be of comparable difficulty to integer factorization. We present a quantum algorithm that solves arbitrary instances of GI, and which provides a novel approach to determining all automorphisms of a graph. The algorithm converts a GI instance to a combinatorial optimization problem that can be solved using adiabatic quantum evolution. Numerical simulation of the algorithm's quantum dynamics shows that it correctly distinguishes non-isomorphic graphs; recognizes isomorphic graphs; and finds the automorphism group of a graph. We also discuss the algorithm's experimental implementation and show how it can be leveraged to solve arbitrary instances of the NP-Complete Sub-Graph Isomorphism problem.
Adiabatic fission barriers in superheavy nuclei
Jachimowicz, P; Skalski, J
2016-01-01
Using the microscopic-macroscopic model based on the deformed Woods-Saxon single-particle potential and the Yukawa-plus-exponential macroscopic energy we calculated static fission barriers $B_{f}$ for 1305 heavy and superheavy nuclei $98\\leq Z \\leq 126$, including even - even, odd - even, even - odd and odd - odd systems. For odd and odd-odd nuclei, adiabatic potential energy surfaces were calculated by a minimization over configurations with one blocked neutron or/and proton on a level from the 10-th below to the 10-th above the Fermi level. The parameters of the model that have been fixed previously by a fit to masses of even-even heavy nuclei were kept unchanged. A search for saddle points has been performed by the "Imaginary Water Flow" method on a basic five-dimensional deformation grid, including triaxiality. Two auxiliary grids were used for checking the effects of the mass asymmetry and hexadecapole non-axiallity. The ground states were found by energy minimization over configurations and deformations...
Topological States and Adiabatic Pumping in Quasicrystals
Kraus, Yaakov; Lahini, Yoav; Ringel, Zohar; Verbin, Mor; Zilberberg, Oded
2012-02-01
We find a connection between quasicrystals and topological matter, namely that quasicrystals exhibit non-trivial topological phases attributed to dimensions higher than their own [1]. Quasicrystals are materials which are neither ordered nor disordered, i.e. they exhibit only long-range order [2]. This long-range order is usually expressed as a projection from a higher dimensional ordered system. Recently, the unrelated discovery of Topological Insulators [3] defined a new type of materials classified by their topology. We show theoretically and experimentally using photonic lattices, that one-dimensional quasicrystals exhibit topologically-protected boundary states equivalent to the edge states of the two-dimensional Integer Quantum Hall Effect. We harness this property to adiabatically pump light across the quasicrystal, and generalize our results to higher dimensional systems. Hence, quasicrystals offer a new platform for the study of topological phases while their topology may better explain their surface properties.[4pt] [1] Y. E. Kraus, Y. Lahini, Z. Ringel, M. Verbin, and O. Zilberberg, arXiv:1109.5983 (2011).[0pt] [2] C. Janot, Quasicrystals (Clarendon, Oxford, 1994), 2nd ed.[0pt] [3] M. Z. Hasan and C. L. Kane, Rev. Mod. Phys. 82, 3045 (2010).
Axion Haloscopes with Toroidal Geometry at CAPP/IBS
Ko, B R
2016-01-01
The present state of the art axion haloscope employs a cylindrical resonant cavity in a solenoidal field. We, the Center for Axion and Precision Physics Research (CAPP) of the Institute for Basic Science (IBS) in Korea, are also pursuing halo axion discovery using this cylindrical geometry. However, the presence of end caps of cavities increases challenges as we explore higher frequency regions for the axion at above 2 GHz. To overcome these challenges we exploit a toroidal design of cavity and magnetic field. A toroidal geometry offers several advantages, two of which are a larger volume for a given space and greatly reduced fringe fields which interfere with our preamps, in particular the planned quantum-based devices. We introduce the concept of toroidal axion haloscopes and present ongoing research activities and plans at CAPP/IBS.
Toroidal and poloidal momentum transport studies in JET
DEFF Research Database (Denmark)
Tala, T.; Andrew, Y.; Crombe, K.;
2007-01-01
This paper reports on the recent studies of toroidal and poloidal momentum transport in JET. The ratio of the global energy confinement time to the momentum confinement is found to be close to tau(E)/tau(phi) = 1 except for the low density or low collisionality discharges where the ratio is tau...... of toroidal velocity using the Weiland model and GLF23 also confirm that the ratio chi(phi)/chi(i) approximate to 0.4 reproduces the core toroidal velocity profiles well and similar accuracy with the ion temperature profiles. Concerning poloidal velocities on JET, the experimental measurements show...... is the turbulence driven flow through the Reynolds stress. Both CUTIE and TRB turbulence codes show the existence of an anomalous poloidal velocity, being significantly larger than the neo-classical values. And similarly to experiments, the poloidal velocity profiles peak in the vicinity of the ITB and seem...
Dynamics of the Disruption Halo Current Toroidal Asymmetry in NSTX
Energy Technology Data Exchange (ETDEWEB)
S.P. Gerhardt
2012-09-27
This paper describes the dynamics of disruption halo current non-axisymmetries in the lower divertor of the National Spherical Torus Experiment [M. Ono, et al. Nuclear Fusion 40, 557 (2000)]. While. The halo currents typically have a strongly asymmetric structure where they enter the divertor floor, and this asymmetry has been observed to complete up to 7 toroidal revolutions over the duration of the halo current pulse. However, the rotation speed and toroidal extend of the asymmetry can vary significantly during the pulse. The rotation speed, halo current pulse duration, and total number of revolutions tend to be smaller in cases with large halo currents. The halo current pattern is observed to become toroidally symmetric at the end of the halo current pulse. It is proposed that this symmeterization is due to the loss of most or all of the closed field line geometry in the final phase of the vertical displacement event.
Analytical solutions for Tokamak equilibria with reversed toroidal current
Energy Technology Data Exchange (ETDEWEB)
Martins, Caroline G. L.; Roberto, M.; Braga, F. L. [Departamento de Fisica, Instituto Tecnologico de Aeronautica, Sao Jose dos Campos, Sao Paulo 12228-900 (Brazil); Caldas, I. L. [Instituto de Fisica, Universidade de Sao Paulo, 05315-970 Sao Paulo, SP (Brazil)
2011-08-15
In tokamaks, an advanced plasma confinement regime has been investigated with a central hollow electric current with negative density which gives rise to non-nested magnetic surfaces. We present analytical solutions for the magnetohydrodynamic equilibria of this regime in terms of non-orthogonal toroidal polar coordinates. These solutions are obtained for large aspect ratio tokamaks and they are valid for any kind of reversed hollow current density profiles. The zero order solution of the poloidal magnetic flux function describes nested toroidal magnetic surfaces with a magnetic axis displaced due to the toroidal geometry. The first order correction introduces a poloidal field asymmetry and, consequently, magnetic islands arise around the zero order surface with null poloidal magnetic flux gradient. An analytic expression for the magnetic island width is deduced in terms of the equilibrium parameters. We give examples of the equilibrium plasma profiles and islands obtained for a class of current density profile.
Bi-2223 HTS winding in toroidal configuration for SMES coil
Energy Technology Data Exchange (ETDEWEB)
Kondratowicz-Kucewicz, B; Kozak, S; Kozak, J; Wojtasiewicz, G; Majka, M [Electrotechnical Institute in Warsaw (Poland); Janowski, T, E-mail: t.janowski@pollub.p [Lublin University of Technology (Poland)
2010-06-01
Energy can be stored in the magnetic field of a coil. Superconducting Magnetic Energy Storage (SMES) is very promising as a power storage system for load levelling or power stabilizer. However, the strong electromagnetic force caused by high magnetic field and large coil current is a problem in SMES systems. A toroidal configuration would have a much less extensive external magnetic field and electromagnetic forces in winding. The paper describes the design of HTS winding for SMES coil in modular toroid configuration consist of seven Bi-2223 double-pancakes as well as numerical analysis of SMES magnet model using FLUX 3D package. As the results of analysis the paper presents the optimal coil configuration and the parameters such as radius of toroidal magnet, energy stored in magnet and magnetic field distribution.
Toroidal drift waves with an equilibrium velocity field
International Nuclear Information System (INIS)
The author investigated the effect of a radially sheared poloidal velocity field on the toroidal drift wave which is well known to escape magnetic shear damping through toroidal coupling between different poloidal harmonics centered on individual rational surfaces. He endeavored to model the velocity profile according to that observed at the plasma edge during H-mode shots. The resultant wave formed by the interference of different poloidal harmonics now sees an antiwell created by the H-mode type velocity profile in the radial direction (in contrast to a well formed by the diamagnetic frequency in the absence of velocity fields). The wave, therefore, convects energy outward and hence undergoes damping. Outgoing wave boundary condition then introduces a negative imaginary contribution to the global eigenvalue -- once again confirming the stabilizing role of H-mode type velocity profiles. On the other hand, L-mode type velocity profiles have destabilizing action on toroidal drift waves
Vlasov tokamak equilibria with sheared toroidal flow and anisotropic pressure
Energy Technology Data Exchange (ETDEWEB)
Kuiroukidis, Ap, E-mail: kouirouki@astro.auth.gr [Technological Education Institute of Serres, 62124 Serres (Greece); Throumoulopoulos, G. N., E-mail: gthroum@uoi.gr [Department of Physics, University of Ioannina, GR 451 10 Ioannina (Greece); Tasso, H., E-mail: het@ipp.mpg.de [Max-Planck-Institut für Plasmaphysik, D-85748 Garching (Germany)
2015-08-15
By choosing appropriate deformed Maxwellian ion and electron distribution functions depending on the two particle constants of motion, i.e., the energy and toroidal angular momentum, we reduce the Vlasov axisymmetric equilibrium problem for quasineutral plasmas to a transcendental Grad-Shafranov-like equation. This equation is then solved numerically under the Dirichlet boundary condition for an analytically prescribed boundary possessing a lower X-point to construct tokamak equilibria with toroidal sheared ion flow and anisotropic pressure. Depending on the deformation of the distribution functions, these steady states can have toroidal current densities either peaked on the magnetic axis or hollow. These two kinds of equilibria may be regarded as a bifurcation in connection with symmetry properties of the distribution functions on the magnetic axis.
Adiabatic rotation, quantum search, and preparation of superposition states
Siu, M. Stewart
2007-06-01
We introduce the idea of using adiabatic rotation to generate superpositions of a large class of quantum states. For quantum computing this is an interesting alternative to the well-studied “straight line” adiabatic evolution. In ways that complement recent results, we show how to efficiently prepare three types of states: Kitaev’s toric code state, the cluster state of the measurement-based computation model, and the history state used in the adiabatic simulation of a quantum circuit. We also show that the method, when adapted for quantum search, provides quadratic speedup as other optimal methods do with the advantages that the problem Hamiltonian is time independent and that the energy gap above the ground state is strictly nondecreasing with time. Likewise the method can be used for optimization as an alternative to the standard adiabatic algorithm.
Application of adiabatic calorimetry to metal systems. Final report
International Nuclear Information System (INIS)
Research on the application of adiabatic calorimetry to metal systems is described. Investigations into formation of pearlite in steels, ferromagnetic effects, cold working and annealing, solid solution alloys, pure solid metals, and pure liquid metals, are briefly described
Magnesium Diboride Superconducting Coils for Adiabatic Demagnetization Refrigerators (ADR's) Project
National Aeronautics and Space Administration — For Adiabatic Demagnetization Refrigerators(ADR's) for space it is desirable to have very light weight, small diameter, high current density superconducting wires...
AN ADIABATIC APPROACH FOR LOW POWER FULL ADDER DESIGN
Directory of Open Access Journals (Sweden)
Prof. Dinesh Chandra
2011-09-01
Full Text Available Over the past decade, several adiabatic logic styles have been reported. This paper deals with the design of a 1-bit full adder using several adiabatic logic styles, which are derived from static CMOS logic, without a large change. The full adders are designed using 180nm technology parameters provided by predictive technology and simulated using HSPICE. The full adders designed are compared in terms of average power consumption with different values of load capacitance, temperature and input frequency. The different designs of full adder are also compared on the basis of propagation delay exhibit by them. It is found that, full adders designed with adiabatic logic styles tends to consume very low power in comparison to full adder designed with static CMOS logic. Under certain operating conditions, one of adiabatic designs of full adder achieves upto 74% power saving in comparison to the full adder designedwith static CMOS logic.
Development and verification of printed circuit board toroidal transformer model
DEFF Research Database (Denmark)
Pejtersen, Jens; Mønster, Jakob Døllner; Knott, Arnold
2013-01-01
by comparing calculated parameters with 3D finite element simulations and experimental measurement results. The developed transformer model shows good agreement with the simulated and measured results. The model can be used to predict the parameters of printed circuit board toroidal transformer configurations......An analytical model of an air core printed circuit board embedded toroidal transformer configuration is presented. The transformer has been developed for galvanic isolation of very high frequency switch-mode dc-dc power converter applications. The theoretical model is developed and verified...
Experiments with a fully toroidal Extrap Z-pinch
International Nuclear Information System (INIS)
In the Extrap plasma confinement scheme, a Z-pinch is produced along the null of an octupole field generated by currents in external conductors. In the paper, studies of the discharge startup process in a fully toroidal configuration are described. Startup involves first breaking down a toroidal discharge and then driving up the current in order to reach the pinch parameter regime. Current densities of 2x106 A·m-2 have been achieved. The estimated plasma density is 6x1020m-3, and the temperature is about 4 eV. These parameters correspond to pinch conditions. (author)
Toroidal Spiral Strings in Higher-dimensional Spacetime
Igata, Takahisa; Ishihara, Hideki
2010-01-01
We report on our progress in research of separability of the Nambu-Goto equation for test strings with a symmetric configuration in a shape of toroidal spiral in a five-dimensional Kerr-AdS black hole. In particular, for a Hopf loop string which is a special class of the toroidal spirals, we show the complete separation of variables occurs in two cases, Kerr background and Kerr-AdS background with equal angular momenta. We also obtain the dynamical solution for the Hopf loop around a black ho...
Comparative study between toroidal coordinates and the magnetic dipole field
Chávez-Alarcón, Esteban
2012-01-01
There is a similar behaviour between the toroidal coordinates and the dipole magnetic field produced by a circular loop. In this work we evaluate up to what extent the former can be used as a representation of the latter. While the tori in the toroidal coordinates have circular cross sections, those of the circular loop magnetic field are nearly elliptical ovoids, but they are very similar for large aspect ratios.The centres of the latter displace from the axis faster than the former. By making a comparison between tori of similar aspect ratios, we find quantitative criteria to evaluate the accuracy of the approximation.
Induction Motor with Switchable Number of Poles and Toroidal Winding
Directory of Open Access Journals (Sweden)
MUNTEANU, A.
2011-05-01
Full Text Available This paper presents a study of an induction motor provided with toroidal stator winding. The ring-type coils offer a higher versatility in obtaining a different number of pole pairs by means of delta/star and series/parallel connections respectively. As consequence, the developed torque can vary within large limits and the motor can be utilized for applications that require, for example, high load torque values for a short time. The study involves experimental tests and FEM simulation for an induction machine with three configurations of pole pairs. The conclusions attest the superiority of the toroidal winding for certain applications such as electric vehicles or lifting machines.
Reevaluation of the Braginskii viscous force for toroidal plasma
Johnson, Robert W
2009-01-01
The model by Braginskii for the viscous stress tensor is used to determine the shear and gyroviscous forces acting within a toroidally confined plasma. Comparison is made to previous evaluations which contain an inconsistent treatment of the radial derivative and neglect the effect of the pitch angle. A radial gyroviscous force is found to survive the limit of constant density and rigid toroidal rotation of the flux surface, and a radial shear viscous force may develop for sufficient vertical asymmetry to the ion velocity profile.
The Linear Evolution of Tearing Mode in Toroidal Geometry*
Institute of Scientific and Technical Information of China (English)
任慎明; 俞国扬
2001-01-01
A set of linearly-reduced MHD equations in toroidal geometry has been solved numerically in flux coordinate with toroidal coupling. In the case of q ＞ 1 on the magnetic axis.where q is the safety factor, the result shows that an unstable 2/1 tearing mode destabilizes both 1/1 and 3/1 modes. The 1/1 and 3/1 modes contribute local perturbations on the resonant surface of q = 2. And the 2/1 mode also contributes a local perturbation on the resonant surface of q = 3.``
Toroidal vortices as a solution to the dust migration problem
Loren-Aguilar, Pablo
2015-01-01
In an earlier letter, we reported that dust settling in protoplanetary discs may lead to a dynamical dust-gas instability that produces global toroidal vortices. In this letter, we investigate the evolution of a dusty protoplanetary disc with two different dust species (1 mm and 50 cm dust grains), under the presence of the instability. We show how toroidal vortices, triggered by the interaction of mm grains with the gas, stop the radial migration of metre-sized dust, potentially offering a natural and efficient solution to the dust migration problem.
Polygonal silica toroidal microcavity for controlled optical coupling
Kato, Takumi; Tanabe, Takasumi
2012-01-01
We fabricated polygonal silica toroidal microcavities to achieve stable mechanical coupling with an evanescent coupler such as a tapered fiber. The polygonal cavity was fabricated by using a combination of isotropic etching, anisotropic etching and laser reflow. It offers both high and low coupling efficiencies with the cavity mode even when the coupler is in contact with the cavity, which offers the possibility of taking the device outside the laboratory. A numerical simulation showed that an octagonal silica toroidal microcavity had an optical quality factor of 8.8\\times10^6.
Field calculation of D0 toroids and comparison with measurement
Energy Technology Data Exchange (ETDEWEB)
Yamada, R.; Ostiguy, F.; Brzezniak, J.
1992-06-01
The magnetic structure of the D0 detector is described in an earlier report. The two-dimensional code POISSON was used for the initial design of the magnetic structures and the magnetic properties of the D0 toroids. During the construction, the two-dimensional code ANSYS was used to perform more detailed calculations. Full three-dimensional analysis was also performed using the code TOSCA. These new results are reported here and compared with measurements. In this study the magnetic flux in all toroids, CF, EF, and SAMUS is set in the same direction.
Adiabatic instability in coupled dark energy-dark matter models
Bean, Rachel; Flanagan, Eanna E.; Trodden, Mark
2007-01-01
We consider theories in which there exists a nontrivial coupling between the dark matter sector and the sector responsible for the acceleration of the universe. Such theories can possess an adiabatic regime in which the quintessence field always sits at the minimum of its effective potential, which is set by the local dark matter density. We show that if the coupling strength is much larger than gravitational, then the adiabatic regime is always subject to an instability. The instability, whi...
Hybrid adiabatic potentials in the QCD string model
Kalashnikova, Yu S; Kalashnikova, Yu.S.
2003-01-01
The short- and intermediate-distance behaviour of the hybrid adiabatic potentials is calculated in the framework of the QCD string model. The calculations are performed with the inclusion of Coulomb force. Spin-dependent force and the so-called string correction term are treated as perturbation at the leading potential-type regime. Reasonably good agreement with lattice measurements takes place for adiabatic curves excited with magnetic components of field strength correlators.
Adiabatic Quantum Programming: Minor Embedding With Hard Faults
Klymko, Christine; Sullivan, Blair D.; Humble, Travis S.
2012-01-01
Adiabatic quantum programming defines the time-dependent mapping of a quantum algorithm into an underlying hardware or logical fabric. An essential step is embedding problem-specific information into the quantum logical fabric. We present algorithms for embedding arbitrary instances of the adiabatic quantum optimization algorithm into a square lattice of specialized unit cells. These methods extend with fabric growth while scaling linearly in time and quadratically in footprint. We also provi...
Adiabatic CMB perturbations in pre-big bang string cosmology
Enqvist, Kari; Enqvist, Kari; Sloth, Martin S.
2002-01-01
We consider the pre-big bang scenario with a massive axion field which starts to dominate energy density when oscillating in an instanton-induced potential and subsequently reheats the universe as it decays into photons, thus creating adiabatic CMB perturbations. We find that the fluctuations in the axion field can give rise to a nearly flat spectrum of adiabatic perturbations with a spectral tilt $\\Delta n$ in the range $-0.1 \\lesssim \\Delta n \\lesssim 0.3$.
Preparation of Entangled States of Three Particles by Adiabatic Passage
Institute of Scientific and Technical Information of China (English)
郭建友
2002-01-01
We propose a novel technique for the creation of entangled states of three particles, based upon an adiabatic passage induced by a suitably crafted time-dependent external field. We derive the corresponding adiabatic and bare conditions for the preparation of entangled states. We obtain the time evolutions of the energy of the system and the populations involving the initial state and target entangled state.
ENTROPY-VORTEX WAVES IN NON-ADIABATIC FLOWS
Energy Technology Data Exchange (ETDEWEB)
Ibáñez S, Miguel H., E-mail: mhibanez@yahoo.com [Departamento de Ciencias Básicas, Facultad de Ingeniería, Universidad Autónoma del Caribe, Barranquilla (Colombia)
2016-02-20
The Ertel theorem on the vorticity along the flow of adiabatic fluids is generalized for non-adiabatic flows. Several limiting cases are analyzed and the results are applied to flows behind different hydrodynamics fronts, particularly to thermal fronts (heat and cooling fronts). An important conclusion of the present analysis is that vorticity is inherent in the condensation’s (or hot spots) formation by thermal instabilities in plasma flows. Implications for several astrophysical plasmas are outlined.
Dependence of adiabatic population transfer on pulse profile
Indian Academy of Sciences (India)
S Dasgupta; T kushwaha; D Goswami
2006-06-01
Control of population transfer by rapid adiabatic passage has been an established technique wherein the exact amplitude profile of the shaped pulse is considered to be insignificant. We study the effect of ultrafast shaped pulses for two-level systems, by density-matrix approach. However, we find that adiabaticity depends simultaneously on pulse profile as well as the frequency modulation under non-resonant conditions.
Adiabatic invariant value variation under shortwave band subcritical conditions
Svistunov, K. V.; Tinin, M. V.
1985-04-01
The possibility of significant variations of the adiabatic invariant is examined for the propagation of radio waves in an irregular Earth-ionosphere waveguide with a parabolic dependence of permittivity on height. Numerical and analytical results indicate that nonexponential deviations of the adiabatic invariant can occur not only when the characteristic size of horizontal irregularity decreases (e.g., during resonant beam excitation) but also in quasi-critical conditions and for smoothly irregular waveguides.
Fuel efficiency, availability and compressor station configuration
Energy Technology Data Exchange (ETDEWEB)
Lubomirsky, Matt; Kurz, Rainer [Solar Turbines Inc., San Diego, CA (United States); Klimov, Pavel [Intergas Central Asia, Astana (Kazakhstan)
2009-12-19
Compressor stations play a very important role in the success of a gas pipeline design and a careful selection of centrifugal compressors and drivers are key aspects for the success of the project. The state of the art design available today for this equipment provides overall high thermodynamic performance and consequently minimizes installed power requirements and energy usage with significant savings on operating expenses during the economic life of the project For any application of machinery in a pipeline compression station, one of the key questions to answer is the number of units to install to meet the flow requirements of the pipeline. Depending on the load profile of the pipeline, the answers may look different. Other factors to consider include the fact that gas turbines can produce a significant amount of additional power at lower ambient temperatures. So, even for constant load of the pipeline, the relative load of the driver changes. In this paper, a typical transcontinental pipeline with multiple compressor stations is evaluated. The determination of the exact hydraulic behavior of the pipeline is part of the modeling effort. The site ambient conditions, with a significant swing in ambient temperatures are considered. The issue discussed in this paper evolves around the availability that can be achieved with various configurations, based on actually achieved reliability and availability numbers. The other large impact on operating costs, fuel consumption will be discussed. Here, the choice of the number of installed units has a distinct impact on annual fuel consumption, as well as the capacity of the pipeline during various scenarios. (author)
Sound reduction of air compressors using a systematic approach
Moylan, Justin Tharp
The noise emitted by portable electric air compressors can often be a nuisance or potentially hazardous to the operator or others nearby. Therefore, reducing the noise of these air compressors is desired. This research focuses on compressors with a reciprocating piston design as this is the most common type of pump design for portable compressors. An experimental setup was developed to measure the sound and vibration of the air compressors, including testing inside a semi-anechoic chamber. The design of a quiet air compressor was performed in four stages: 1) Teardown and benchmarking of air compressors, 2) Identification and isolation of noise sources, 3) Development of individual means to quiet noise sources, 4) Selection and testing of integrated solutions. The systematic approach and results for each of these stages will be discussed. Two redesigned solutions were developed and measured to be approximately 65% quieter than the previous unmodified compressor. An additional analysis was performed on the solutions selected by the participants involved in the selection process. This analysis involved determining which of the design criteria each participant considered most important when selecting solutions. The results from each participant were then compared to their educational background and experience and correlations were identified. The correlations discovered suggest that educational background and experience may be key determinants for the preference models developed.
Air Compressor Driving with Synchronous Motors at Optimal Parameters
Directory of Open Access Journals (Sweden)
Iuliu Petrica
2010-10-01
Full Text Available In this paper a method of optimal compensation of the reactive load by the synchronous motors, driving the air compressors, used in mining enterprises is presented, taking into account that in this case, the great majority of the equipment (compressors, pumps are generally working a constant load.
Axial and Centrifugal Compressor Mean Line Flow Analysis Method
Veres, Joseph P.
2009-01-01
This paper describes a method to estimate key aerodynamic parameters of single and multistage axial and centrifugal compressors. This mean-line compressor code COMDES provides the capability of sizing single and multistage compressors quickly during the conceptual design process. Based on the compressible fluid flow equations and the Euler equation, the code can estimate rotor inlet and exit blade angles when run in the design mode. The design point rotor efficiency and stator losses are inputs to the code, and are modeled at off design. When run in the off-design analysis mode, it can be used to generate performance maps based on simple models for losses due to rotor incidence and inlet guide vane reset angle. The code can provide an improved understanding of basic aerodynamic parameters such as diffusion factor, loading levels and incidence, when matching multistage compressor blade rows at design and at part-speed operation. Rotor loading levels and relative velocity ratio are correlated to the onset of compressor surge. NASA Stage 37 and the three-stage NASA 74-A axial compressors were analyzed and the results compared to test data. The code has been used to generate the performance map for the NASA 76-B three-stage axial compressor featuring variable geometry. The compressor stages were aerodynamically matched at off-design speeds by adjusting the variable inlet guide vane and variable stator geometry angles to control the rotor diffusion factor and incidence angles.
Compressor Study to Meet Large Civil Tilt Rotor Engine Requirements
Veres, Joseph P.
2009-01-01
A vehicle concept study has been made to meet the requirements of the Large Civil Tilt Rotorcraft vehicle mission. A vehicle concept was determined, and a notional turboshaft engine system study was conducted. The engine study defined requirements for the major engine components, including the compressor. The compressor design-point goal was to deliver a pressure ratio of 31:1 at an inlet weight flow of 28.4 lbm/sec. To perform a conceptual design of two potential compressor configurations to meet the design requirement, a mean-line compressor flow analysis and design code were used. The first configuration is an eight-stage axial compressor. Some challenges of the all-axial compressor are the small blade spans of the rear-block stages being 0.28 in., resulting in the last-stage blade tip clearance-to-span ratio of 2.4 percent. The second configuration is a seven-stage axial compressor, with a centrifugal stage having a 0.28-in. impeller-exit blade span. The compressors conceptual designs helped estimate the flow path dimensions, rotor leading and trailing edge blade angles, flow conditions, and velocity triangles for each stage.
Dual-worm screw compressors; Compresseurs bi-vis
Energy Technology Data Exchange (ETDEWEB)
Baleydier, J.P. [Bitzer France, 69 - Lyon (France)
1997-12-31
Low power worm-screw moto-compressors are used in any king of refrigerating machineries and more and more in air conditioning systems. This paper presents the principle of dual-screw moto-compressors: worm-screw technology, role of oil (lubrication, tightness, cooling), compression, internal pressure, power reduction, lubrication, economizer, operation, model selection and accessories. (J.S.)
DESIGN PARAMETERS OF CENTRIFUGAL COMPRESSOR INDUCER
Directory of Open Access Journals (Sweden)
Saim KOÇAK
1998-03-01
Full Text Available Design characteristics of centrifugal compressor impellers working with compressible fluids are analyzed, and the design parameters of inducer are defined. The effects of incidence, deviation and deflection angles, relative eddy, rotating stall and Mach number are investigated. The relation between minimum relative Mach number of inducer and flow angle is investigated and it is observed that the minimum Mach number occurs for flow angle values between -680 and -520 . In the design, the effect of a 100 difference in flow angle is found to be less than 1 % on minimum relative Mach number.
Energy Technology Data Exchange (ETDEWEB)
Podesta, M; Fredrickson, E D; Gorelenkov, N N; LeBlanc, B P; Heidbrink, W W; Crocker, N A; Kubota, S
2010-08-19
The effects of a sheared toroidal rotation on the dynamics of bursting Toroidicity-induced Alfven eigenmodes are investigated in neutral beam heated plasmas on the National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40 557 (2000)]. The modes have a global character, extending over most of the minor radius. A toroidal rotation shear layer is measured at the location of maximum drive for the modes. Contrary to results from other devices, no clear evidence of increased damping is found. Instead, experiments with simultaneous neutral beam and radio-frequency auxiliary heating show a strong correlation between the dynamics of the modes and the instability drive. It is argued that kinetic effects involving changes in the mode drive and damping mechanisms other than rotation shear, such as continuum damping, are mostly responsible for the bursting dynamics of the modes.
International Nuclear Information System (INIS)
The effects of a sheared toroidal rotation on the dynamics of bursting Toroidicity-induced Alfven eigenmodes are investigated in neutral beam heated plasmas on the National Spherical Torus Experiment (NSTX) (M. Ono et al., Nucl. Fusion 40 557 (2000)). The modes have a global character, extending over most of the minor radius. A toroidal rotation shear layer is measured at the location of maximum drive for the modes. Contrary to results from other devices, no clear evidence of increased damping is found. Instead, experiments with simultaneous neutral beam and radio-frequency auxiliary heating show a strong correlation between the dynamics of the modes and the instability drive. It is argued that kinetic effects involving changes in the mode drive and damping mechanisms other than rotation shear, such as continuum damping, are mostly responsible for the bursting dynamics of the modes.
Controlling the toroidal excitations in metamaterials for high-Q response
Fan, Yuancheng; Fu, Quanhong; Wei, Zeyong; Li, Hongqiang
2016-01-01
The excitation of toroidal multipoles in metamaterials was investigated for high-Q response at a subwavelength scale. In this study, we explored the optimization of toroidal excitations in a planar metamaterial comprised of asymmetric split ring resonators (ASRRs). It was found that the scattering power of toroidal dipole can be remarkably strengthened by adjusting the characteristic parameter of ASRRs: asymmetric factor. Interestingly, the improvement in toroidal excitation accompanies increasing of the Q-factor of the toroidal metamaterial, it is shown that both the scattering power of toroidal dipole and the Q-factor were increased near one order by changing the asymmetric factor of ASRRs. The optimization in excitation of toroidal multipoles provide opportunity to further increase the Q-factor of toroidal metamaterial and boost light-matter interactions at the subwavelength scale for potential applications in low-power nonlinear processing and sensitive photonic applications.
Transport and Dynamics in Toroidal Fusion Systems
Energy Technology Data Exchange (ETDEWEB)
Sovinec, Carl [Univ. of Wisconsin, Madison, WI (United States)
2016-09-07
The study entitled, "Transport and Dynamics in Toroidal Fusion Systems," (TDTFS) applied analytical theory and numerical computation to investigate topics of importance to confining plasma, the fourth state of matter, with magnetic fields. A central focus of the work is how non-thermal components of the ion particle distribution affect the "sawtooth" collective oscillation in the core of the tokamak magnetic configuration. Previous experimental and analytical research had shown and described how the oscillation frequency decreases and amplitude increases, leading to "monster" or "giant" sawteeth, when the non-thermal component is increased by injecting particle beams or by exciting ions with imposed electromagnetic waves. The TDTFS study applied numerical computation to self-consistently simulate the interaction between macroscopic collective plasma dynamics and the non-thermal particles. The modeling used the NIMROD code [Sovinec, Glasser, Gianakon, et al., J. Comput. Phys. 195, 355 (2004)] with the energetic component represented by simulation particles [Kim, Parker, Sovinec, and the NIMROD Team, Comput. Phys. Commun. 164, 448 (2004)]. The computations found decreasing growth rates for the instability that drives the oscillations, but they were ultimately limited from achieving experimentally relevant parameters due to computational practicalities. Nonetheless, this effort provided valuable lessons for integrated simulation of macroscopic plasma dynamics. It also motivated an investigation of the applicability of fluid-based modeling to the ion temperature gradient instability, leading to the journal publication [Schnack, Cheng, Barnes, and Parker, Phys. Plasmas 20, 062106 (2013)]. Apart from the tokamak-specific topics, the TDTFS study also addressed topics in the basic physics of magnetized plasma and in the dynamics of the reversed-field pinch (RFP) configuration. The basic physics work contributed to a study of two-fluid effects on interchange dynamics, where
Numerical Investigation of Flow in a Centrifugal Compressor
Grishin, Yu. A.; Bakulin, V. N.
2015-09-01
With the use of the domestic software suite of computational hydrodynamics Flow Vision based on application of the method of control volumes, numerical simulation of air composition and delivery by a centrifugal compressor employed for supercharging a piston engine has been carried out. The head-flow characteristics of the compressor, as well as the 3D fields of flow velocity and pressure distributions in the elements of the compressor flow passage, including the interblade channels of the impeller, have been obtained for various regimes. In the regimes of diminished air flow rate, surging phenomena are identified, characterized by a return flow. The application of the technique of numerical experiment will make it possible from here on to carry out design optimization of the compressor flow passage profile and thus to improve its basic characteristics — the degree of pressure increase, compressed air flow rate, and the efficiency — as well as to reduce the costs of the development and production of compressors.
Institute of Scientific and Technical Information of China (English)
LUO Shao-Kai
2007-01-01
For a Lagrangian system with the action of small disturbance, the Lie symmetrical perturbation and a new type of non-Noether adiabatic invariant are presented in general infinitesimal transformation groups. On the basis of the invariance of disturbed Lagrangian systems under general infinitesimal transformations, the determining equations of Lie symmetries of the system are constructed. Based on the definition of higher-order adiabatic invariants of a mechanical system, a new type of adiabatic invariant, i.e. generalized Lutzky adiabatic invariants, of a disturbed Lagrangian system are obtained by investigating the perturbation of Lie symmetries for a Lagrangian system with the action of small disturbance. Finally, an example is given to illustrate the application of the method and results.
IC ENGINE SUPERCHARGING AND EXHAUST GAS RECIRCULATION USING JET COMPRESSOR
Directory of Open Access Journals (Sweden)
Adhimoulame Kalaisselvane
2010-01-01
Full Text Available Supercharging is a process which is used to improve the performance of an engine by increasing the specific power output whereas exhaust gas recirculation reduces the NOx produced by engine because of supercharging. In a conventional engine, supercharger functions as a compressor for the forced induction of the charge taking mechanical power from the engine crankshaft. In this study, supercharging is achieved using a jet compressor. In the jet compressor, the exhaust gas is used as the motive stream and the atmospheric air as the propelled stream. When high pressure motive stream from the engine exhaust is expanded in the nozzle, a low pressure is created at the nozzle exit. Due to this low pressure, atmospheric air is sucked into the expansion chamber of the compressor, where it is mixed and pressurized with the motive stream. The pressure of the mixed stream is further increased in the diverging section of the jet compressor. A percentage volume of the pressurized air mixture is then inducted back into the engine as supercharged air and the balance is let out as exhaust. This process not only saves the mechanical power required for supercharging but also dilutes the constituents of the engine exhaust gas thereby reducing the emission and the noise level generated from the engine exhaust. The geometrical design parameters of the jet compressor were obtained by solving the governing equations using the method of constant rate of momentum change. Using the theoretical design parameters of the jet compressor, a computational fluid dinamics analysis using FLUENT software was made to evaluate the performance of the jet compressor for the application of supercharging an IC engine. This evaluation turned out to be an efficient diagnostic tool for determining performance optimization and design of the jet compressor. A jet compressor was also fabricated for the application of supercharging and its performance was studied.
G. Perinic
2001-01-01
Most recent pictures taken during the factory acceptance of the compressor skids at Samifi-Babcock. All pictures show the second stage compressor skid. Picture two was taken during the leak tests and shows all the pockets around flanges and valves.
Dynamical fluctuations in classical adiabatic processes: General description and their implications
Zhang, Qi; Gong, Jiangbin; Oh, C. H.
2010-01-01
Dynamical fluctuations in classical adiabatic processes are not considered by the conventional classical adiabatic theorem. In this work a general result is derived to describe the intrinsic dynamical fluctuations in classical adiabatic processes. Interesting implications of our general result are discussed via two subtopics, namely, an intriguing adiabatic geometric phase in a dynamical model with an adiabatically moving fixed-point solution, and the possible "pollution" to Hannay's angle or...
Homogeneous Construction of the Toroidal Lie Algebra of Type A1
Institute of Scientific and Technical Information of China (English)
Haifeng Lian; Cui Chen; Qinzhu Wen
2007-01-01
In this paper,we consider an analogue of the level two homogeneous construc-tion of the affine Kac-Moody algebra A1(1) by vertex operators.We construct modules for the toroidal Lie algebra and the extended toroidal Lie algebra of type A1.We also prove that the module is completely reducible for the extended toroidal Lie algebra.
Compressor Part II: Volute Flow Predictions
Directory of Open Access Journals (Sweden)
Yu-Tai Lee
1999-01-01
Full Text Available A numerical method that solves the Reynolds-averaged Navier-Stokes equations is used to study an inefficient component of a shipboard air-conditioning HCFC-124 compressor system. This high-loss component of the centrifugal compressor was identified as the volute through a series of measurements given in Part I of the paper. The predictions were made using three grid topologies. The first grid closes the connection between the cutwater and the discharge diffuser. The other two grids connect the cutwater area with the discharge diffuser. Experiments were performed to simulate both the cutwater conditions used in the predictions. Surface pressures along the outer wall and near the inlet of the volute were surveyed for comparisons with the predictions. Good agreements between the predicted results and the measurements validate the calculations. Total pressure distributions and flow stream traces from the prediction results support the loss distribution through the volute. A modified volute configuration is examined numerically for further loss comparison.
Centrifugal compressor design choices for chillers
Energy Technology Data Exchange (ETDEWEB)
Brasz, J.J. [United Technologies Carrier, New York, NY (United States)
1999-07-01
The use of centrifugal compressors in the air conditioning and refrigeration industry is currently limited to large water cooled chillers varying in size from about 0.5 to 6 MW cooling capacity. These systems are primarily used for comfort or process cooling applications. All systems try to chill relatively large amounts of indoor or process water by a few degrees Celsius in a refrigerant evaporator. The heat removed from the chilled water is released together with the heat of compression in a refrigerant condenser to cooling tower water, from where it is discharged to the atmosphere. Different centrifugal compressor design concepts are used by the various chiller manufacturers: single-stage versus multi-stage, vaneless versus vaned diffuser, hermetic versus open-drive motors, shrouded versus open impellers, fixed versus variable diffuser geometry, low- versus high-pressure refrigerant. This variability seems strange for a mature industry like the air conditioning and refrigeration industry. This paper will show that the reason for this variability is the product compromise between the various conflicting system requirements with respect to size, cost, efficiency and refrigerant choice. The different system applications of the chillers (e.g. comfort cooling in a equatorial region versus process cooling in a moderate climate zone) play another major role in selecting an optimal centrifugal compression concept. Some general recommendations will be given for applications where a clear choice can be made. (Author)
High Efficiency Centrifugal Compressor for Rotorcraft Applications
Medic, Gorazd; Sharma, Om P.; Jongwook, Joo; Hardin, Larry W.; McCormick, Duane C.; Cousins, William T.; Lurie, Elizabeth A.; Shabbir, Aamir; Holley, Brian M.; Van Slooten, Paul R.
2014-01-01
The report "High Efficiency Centrifugal Compressor for Rotorcraft Applications" documents the work conducted at UTRC under the NRA Contract NNC08CB03C, with cost share 2/3 NASA, and 1/3 UTRC, that has been extended to 4.5 years. The purpose of this effort was to identify key technical barriers to advancing the state-of-the-art of small centrifugal compressor stages; to delineate the measurements required to provide insight into the flow physics of the technical barriers; to design, fabricate, install, and test a state-of-the-art research compressor that is representative of the rear stage of an axial-centrifugal aero-engine; and to acquire detailed aerodynamic performance and research quality data to clarify flow physics and to establish detailed data sets for future application. The design activity centered on meeting the goal set outlined in the NASA solicitation-the design target was to increase efficiency at higher work factor, while also reducing the maximum diameter of the stage. To fit within the existing Small Engine Components Test Facility at NASA Glenn Research Center (GRC) and to facilitate component re-use, certain key design parameters were fixed by UTRC, including impeller tip diameter, impeller rotational speed, and impeller inlet hub and shroud radii. This report describes the design effort of the High Efficiency Centrifugal Compressor stage (HECC) and delineation of measurements, fabrication of the compressor, and the initial tests that were performed. A new High-Efficiency Centrifugal Compressor stage with a very challenging reduction in radius ratio was successfully designed, fabricated and installed at GRC. The testing was successful, with no mechanical problems and the running clearances were achieved without impeller rubs. Overall, measured pressure ratio of 4.68, work factor of 0.81, and at design exit corrected flow rate of 3 lbm/s met the target requirements. Polytropic efficiency of 85.5 percent and stall margin of 7.5 percent were
Compact-Toroid development: status and technical needs
International Nuclear Information System (INIS)
This document contains the description, goals, status, plans, and strategy for the technical development of a class of magnetic confinement configurations collectively identified as Compact Toroids. This component of the magnetic fusion development program has been characterized by its potential for physical compactness and range of output power
Toroidal, compression, and vortical dipole strengths in 124Sn
Kvasil, J; Repko, A; Kleinig, W; Reinhard, P -G; Iudice, N Lo
2012-01-01
The toroidal, compression and vortical dipole strength functions in semi-magic $^{124}$Sn (and partly in doubly-magic $^{100,132}$Sn) are analyzed within the random-phase-approximation method with the SkT6, SkI3, SLy6, SV-bas, and SkM* Skyrme forces. The isoscalar (T=0), isovector (T=1), and electromagnetic ('elm') channels are considered. Both convection $j_c$ and magnetization $j_m$ nuclear currents are taken into account. The calculations basically confirm the previous results obtained for $^{208}$Pb with the force SLy6. In particular, it is shown that the vortical and toroidal strengths are dominated by $j_c$ in T=0 channel and by $j_m$ in T=1 and 'elm' channels. The compression strength is always determined by $j_c$. It is also shown that the 'elm' strength (relevant for (e,e') reaction) is very similar to T=1 one. The toroidal mode resides in the region of the pygmy resonance. So, perhaps, this region embraces both irrotational (pygmy) and vortical (toroidal) flows.
Plasma Processes : Minimum dissipative relaxed states in toroidal plasmas
Indian Academy of Sciences (India)
R Bhattacharyya; M S Janaki; B Dasgupta
2000-11-01
Relaxation of toroidal discharges is described by the principle of minimum energy dissipation together with the constraint of conserved global helicity. The resulting Euler-Lagrange equation is solved in toroidal coordinates for an axisymmetric torus by expressing the solutions in terms of Chandrasekhar-Kendall (C-K) eigenfunctions analytically continued in the complex domain. The C-K eigenfunctions are obtained as hypergeometric functions that are solutions of scalar Helmholtz equation in toroidal coordinates in the large aspect-ratio approximation. Equilibria are constructed by assuming the current to vanish at the edge of plasma. For the = 0; = 0 ( and are the poloidal and toroidal mode numbers respectively) relaxed states, the magnetic ﬁeld, current, (safety factor) and pressure proﬁles are calculated for a given value of aspect-ratio of the torus and for different values of the eigenvalue 0. The new feature of the present model is that solutions allow for both tokamak as well as RFP-like behaviour with increase in the values of 0, which is related directly to volt-sec in the experiment.
Evidence of Inward Toroidal Momentum Convection in the JET Tokamak
DEFF Research Database (Denmark)
Tala, T.; Zastrow, K.-D.; Ferreira, J.;
2009-01-01
Experiments have been carried out on the Joint European Torus tokamak to determine the diffusive and convective momentum transport. Torque, injected by neutral beams, was modulated to create a periodic perturbation in the toroidal rotation velocity. Novel transport analysis shows the magnitude an...
First ATLAS Barrel Toroid coil casing arrives at CERN
2002-01-01
The first of eight 25-metre long coil casings for the ATLAS experiment's barrel toroid magnet system arrived at CERN on Saturday 2 March by road from Heidelberg. This structure will be part of the largest superconducting toroid magnet ever made. The first coil casing for the toroidal magnets of Atlas arrives at Building 180. This is the start of an enormous three-dimensional jigsaw puzzle. Each of the eight sets of double pancake coils will be housed inside aluminium coil casings, which in turn will be held inside a stainless steel vacuum vessel. A huge construction, the casing that arrived at CERN measures 25 metres in length and 5 metres in width. It weighs 20 tones. And this is just the beginning of the toroid jigsaw: by early April a batch of four double pancake coils, which altogether weighs 65 tones, will arrive from Ansaldo in Italy. The first vacuum vessel will also be arriving from Felguera in Spain this month. It will take about two years for all these 25 m long structures of casings, coils a...
Stability of toroidal magnetic fields in stellar interiors
Ibañez-Mejia, Juan C
2015-01-01
We present 3D MHD simulations of purely toroidal and mixed poloidal-toroidal magnetic field configurations to study the behavior of the Tayler instability. For the first time the simultaneous action of rotation and magnetic diffusion are taken into account and the effects of a poloidal field on the dynamic evolution of unstable toroidal magnetic fields is included. In the absence of diffusion, fast rotation (rotation rate compared to Alfv\\'en frequency) is able to suppress the instability when the rotation and magnetic axes are aligned and when the radial field strength gradient p 1.5, rapid rotation does not suppress the instability but instead introduces a damping factor to the growth rate in agreement with the analytic predictions. For the mixed poloidal-toroidal fields we find an unstable axisymmetric mode, not predicted analytically, right at the stability threshold for the non-axisymmetric modes; it has been argued that an axisymmetric mode is necessary for the closure of the Tayler-Spruit dynamo loop.
Flat-band assembly for toroidal transformer cores
Mclyman, W. T.
1973-01-01
Toroidal transformer cores are often banded together by means of strap. Spot welds secure strap. Proper tension is obtained by use of special fixture in conjunction with winding of wire which is placed temporarily on core; winding is excited by dc current to hold core halves together magnetically during alignment.
An Overview of Plasma Confinement in Toroidal Systems
Dini, Fatemeh; Baghdadi, Reza; Amrollahi, Reza; Khorasani, Sina
2009-01-01
This overview presents a tutorial introduction to the theory of magnetic plasma confinement in toroidal confinement systems with particular emphasis on axisymmetric equilibrium geometries, and tokamaks. The discussion covers three important aspects of plasma physics: Equilibrium, Stability, and Transport. The section on equilibrium will go through an introduction to ideal magnetohydrodynamics, curvilinear system of coordinates, flux coordinates, extensions to axisymmetric equilibrium, Grad-Sh...
ATLAS-Lowering the first Barrel Toroid coil
2004-01-01
Cranes lowered the first of ATLAS's eight Barrel Toroid coils into the cavern. The part is 25 metres long and the cranes had to hold the 100 tonne coil at a sharp angle while it passed through the 18-metre diameter vertical shaft into the cavern. Then they laid the magnet to a horisontal robust platform. Images from Camera 1
ATLAS-Lowering the first Barrel Toroid coil
CERN Audiovisual Unit
2004-01-01
Cranes lowered the first of ATLAS's eight Barrel Toroid coils into the cavern. The part is 25 meters long and the cranes had to hold the 100 tonne coil at a sharp angle while it passed through the 18-meter diameter vertical shaft into the cavern. Then they laid the magnet to a horizontal robust platform. Images from Camera 2
Theoretical studies of non inductive current drive in compact toroids
Farengo, R; Lifschitz, AF; Caputi, KI; Arista, NR; Clemente, RA
2002-01-01
Three non inductive current drive methods that can be applied to compact toroids axe studied. The use of neutral beams to drive current in field reversed configurations and spheromaks is studied using a Monte Carlo code that includes a complete ionization package and follows the exact particle orbit
The Superconducting Toroid for the New International AXion Observatory (IAXO)
Shilon, I; Silva, H; Wagner, U; Kate, H H J ten
2013-01-01
IAXO, the new International AXion Observatory, will feature the most ambitious detector for solar axions to date. Axions are hypothetical particles which were postulated to solve one of the puzzles arising in the standard model of particle physics, namely the strong CP (Charge conjugation and Parity) problem. This detector aims at achieving a sensitivity to the coupling between axions and photons of one order of magnitude beyond the limits of the current detector, the CERN Axion Solar Telescope (CAST). The IAXO detector relies on a high-magnetic field distributed over a very large volume to convert solar axions to detectable X-ray photons. Inspired by the ATLAS barrel and end-cap toroids, a large superconducting toroid is being designed. The toroid comprises eight, one meter wide and twenty one meters long racetrack coils. The assembled toroid is sized 5.2 m in diameter and 25 m in length and its mass is about 250 tons. The useful field in the bores is 2.5 T while the peak magnetic field in the windings is 5....
Preparing an ATLAS toroid magnet end-cap for lowering
Claudia Marcelloni
2007-01-01
One of the two 13-m high toroid magnet end-caps for the ATLAS experiment being transported from the construction hall to the experimental area. The end-cap will be lowered into the ATLAS cavern and attached to an end of the detector.
Theory of the M = 1 Kink Mode in Toroidal Plasma
de Blank, H. J.; Schep, T. J.
1991-01-01
The energy principle of ideal magnetohydrodynamics (MHD) is used to study the ideal MHD stability of the m = 1 internal kink mode in a toroidal plasma. The equilibrium configurations that are considered allow for a broad region where the safety factor q is close to unity. This region may extend to t
Barrel Toroid fully charged to nominal field, and it works!
Herman ten Kate
After a few weeks of testing up to intermediate currents, finally, on Thursday evening November 9, the current in the Barrel Toroid was pushed up to its nominal value of 20500 A and even 500 A beyond this value to prove that we have some margin. It went surprisingly well. Of course, the 8 coils forming the toroid were already tested individually at the surface but still, some surprise may have come from those parts added to the toroid in the cavern for the first time like the 8 cryoring sections linking the coils as well as the valve box at the bottom in sector 13 regulating the helium flow or the current lead cryostat on the top in sector 5. No training quenches, nothing to worry about, and the test was concluded with a fast dump triggered at 00:40 in the very early morning of November 10. (left) The toroid current during the evening and night of November 9. (right) The test crew oscillated between fear and hope while looking at the control panels as the current approached 21kA. Big relief was in the...
Construction and initial operation of the Advanced Toroidal Facility
International Nuclear Information System (INIS)
The Advanced Toroidal Facility (ATF) torsatron was designed on a physics basis for access to the second stability regime and on an engineering basis for independent fabrication of high-accuracy components. The actual construction, assembly, and initial operation of ATF are compared with the characteristics expected during the design of ATF. 31 refs., 19 figs., 2 tabs
A toroidal inductor integrated in a standard CMOS process
DEFF Research Database (Denmark)
Vandi, Luca; Andreani, Pietro; Temporiti, Enrico;
2007-01-01
This paper presents a toroidal inductor integrated in a standard 0.13 um CMOS process. Finite-elements preliminary simulations are provided to prove the validity of the concept. In order to extract fundamental parameters by means of direct calculations, two different and well-known approaches...
Plasma Heating and Losses in Toroidal Multipole Fields
Energy Technology Data Exchange (ETDEWEB)
Armentrout, C. J.; Barter, J. D.; Breun, R. A.; Cavallo, A. J.; Drake, J. R.; Etzweiler,; Greenwood, J. R.
1974-09-01
The heating and loss of plasmas have been studied in three pulsed, toroidal multipole devices: a large levitated octupole, a small supported octupole and a very .small supported quadrupole. Plasmas are produced by gun injection and heated by electron and ion cyclotron resonance heating and ohmic heating. Electron cyclotron heating rates have been measured over a wide range of parameters, and the results are in quantitative agreement with stochastic heating theory. Electron cyclotron resonance heating produces ions with energies larger than predicted by theory. With the addition of a toroidal field, ohmic heating gives densities as high as 10{sup 13}cm{sup -3} in the toroidal quadrupole and 10{sup 12}cm{sup -3} in the small octupole. Plasma losses for n=5 x 10{sup 9}cm{sup -3} plasmas are inferred from Langmuir probe and Fabry-Perot interferometer measurements, and measured with special striped collectors on the wall and rings. The loss to a levitated ring is measured using a modulated light beam telemeter. The confinement is better than Bohm but considerably worse than classical. Low frequency convective cells which are fixed in space are observed. These cells around the ring are diminished when a weak toroidal field is added, and loss collectors show a vastly reduced flux to the rings. Analysis of the spatial density profile shows features of B-independent diffusion. The confinement is sensitive to some kinds of dc field errors, but surprisingly insensitive to perturbations of the ac confining field.
STUDY ON THERMODYNAMIC MODEL OF A COMPRESSOR WITH ARTIFICIAL NEURAL NETWORKS
Institute of Scientific and Technical Information of China (English)
无
1999-01-01
A new compressor thermodynamic model is set up. Artificial neural networks(ANN) which have self-adjusting functions are adopted to calculate volumetric efficiency and electrical efficiency of a compressor. The new compressor model composed of the theoretical model and ANN reaches more precise results than traditional ones. Furthermore, the new compressor model is of better flexibility in a large scale.
Institute of Scientific and Technical Information of China (English)
WANG Xue-bin
2008-01-01
The coexistent phenomenon of deformed and transformed adiabatic shear bands(ASBs) of ductile metal was analyzed using the JOHNSON-COOK model and gradient-dependent plasticity(GDP). The effects of melting point, density, heat capacity and work to heat conversion factor were investigated. Higher work to heat conversion factor, lower density, lower heat capacity and higher melting point lead to wider transformed ASB and higher local plastic shear deformation between deformed and transformed ASBs. Higher work to heat conversion factor, lower density, lower heat capacity and lower melting point cause higher local plastic shear deformation in the deformed ASB. Three reasons for the scatter in experimental data on the ASB width were pointed out and the advantages of the work were discussed. If the transformed ASB width is used to back-calculate the internal length parameter in the GDP, undoubtedly, the parameter will be extremely underestimated.
Failure analysis of a compressor disc of an air craft
International Nuclear Information System (INIS)
Compressor is an essential part of gas turbine engine producing power for both industrial plants and aircrafts. The primary function of the compressor is to supply enough air at high temperature and pressure to satisfy the requirements of the combustion of fuels. The compressor must increase the pressure of the mass of air received from the air inlet duct and then discharge it to the burners in the required quantity and pressure. A secondary function of the compressor, particularly in aircraft application, is to supply bleed air for various purposes for both the engine and aircraft. Compressor blades operate at relatively low temperature but are highly stressed. Compressor balding is made by forging, extrusion or machining. The recommended material for the blades is generally type 403 stainless steel. In a certain report it was reported that compressor disc of an aircraft engine failed after 320 hours service before completing the recommended life of 750 hours. In the present study it was required to find the reason of failure of the disc. Chemical analysis, macro examination, microscopic examinations were carried out along with micro hardness testing on the teeth portion and fractured surface were taken. After the work it was concluded that chemical composition did not match with the recommended composition and also machine marks, porosity were present near the fractured part which increased stress concentration and contributed to failure. Retained austenite were also present at the failed portion which reduces the hardness value and strength causing premature fracture due to fatigue. (author)
Pressure Field Study of the Tevatron Cold Compressors
Klebaner, A. L.; Martinez, A.; Soyars, W. M.; Theilacker, J. C.
2004-06-01
The Fermilab Tevatron cryogenic system utilizes high-speed centrifugal cold compressors, manufactured by Ishikawajima-Harima Heavy Industries Co. Ltd. (IHI), for high-energy operations. The compressor is designed to pump 60 g/sec of 3.6 K saturated helium vapor at a pressure ratio of 2.8, with an off-design range of 40 to 70 g/sec. Operating speeds are between 40,000 and 95,000 rpm, with a speed of 80,000 rpm at the design point. Different heat loads and magnet quench performance of each of the twenty-four satellite refrigerators dictates different process pressure and flow rates of the cold compressors. Reducing the process flow rate can cause the centrifugal cold compressor to stop pumping and subsequently surge. Tests have been conducted at the Cryogenic Test Facility at Fermilab to map the pressure field and appropriate efficiency of the IHI hydrodynamic cold compressor. The information allows tuning of each of the twenty-four Tevatron satellite refrigerators to avoid cold compressor operation near the surge and choke lines. A new impeller has also been tested. The Tevatron cold compressor pressure field and efficiency data with the new impeller are presented in this paper.
Physics on the adiabatically changed Finslerian manifold and cosmology
Lipovka, Anton A
2016-01-01
In present paper we confirm our previous result [4] that Planck constant is adiabatic invariant of electromagnetic field propagating on the adiabatically changed Finslerian manifold. Direct calculation from cosmological parameters gives value h=6x10(-27) (erg s). We also confirm that Planck constant (and hence other fundamental constants which depend on h) is varied on time due to changing of geometry. As an example the variation of the fine structure constant is calculated. Its relative variation ((da/dt)/a) consist 1.0x10(-18) (1/s). We show that on the Finsler manifold characterized by adiabatically changed geometry, classical free electromagnetic field is quantized geometrically, from the properties of the manifold in such manner that adiabatic invariant of field is ET=6x10(-27)=h. Electrodynamic equations on the Finslerian manifold are suggested. It is stressed that quantization naturally appears from these equations and is provoked by adiabatically changed geometry of manifold. We consider in details tw...
Global adiabaticity and non-Gaussianity consistency condition
Romano, Antonio Enea; Sasaki, Misao
2016-01-01
In the context of single-field inflation, the conservation of the curvature perturbation on comoving slices, $R_c$, on super-horizon scales is one of the assumptions necessary to derive the consistency condition between the squeezed limit of the bispectrum and the spectrum of the primordial curvature perturbation. However, the conservation of $R_c$ holds only after the perturbation has reached the adiabatic limit where the constant mode of $R_c$ dominates over the other (usually decaying) mode. In this case, the non-adiabatic pressure perturbation defined in the thermodynamic sense, $\\delta P_{nad}\\equiv\\delta P-c_w^2\\delta\\rho$ where $c_w^2=\\dot P/\\dot\\rho$, usually becomes also negligible on superhorizon scales. Therefore one might think that the adiabatic limit is the same as thermodynamic adiabaticity. This is in fact not true. In other words, thermodynamic adiabaticity is not a sufficient condition for the conservation of $R_c$ on super-horizon scales. In this paper, we consider models that satisfies $\\d...
Interplay between electric and magnetic effect in adiabatic polaritonic systems
Alabastri, Alessandro
2013-01-01
We report on the possibility of realizing adiabatic compression of polaritonic wave on a metallic conical nano-structure through an oscillating electric potential (quasi dynamic regime). By comparing this result with an electromagnetic wave excitation, we were able to relate the classical lighting-rod effect to adiabatic compression. Furthermore, we show that while the magnetic contribution plays a marginal role in the formation of adiabatic compression, it provides a blue shift in the spectral region. In particular, magnetic permeability can be used as a free parameter for tuning the polaritonic resonances. The peculiar form of adiabatic compression is instead dictated by both the source and the metal permittivity. The analysis is performed by starting from a simple electrostatic system to end with the complete electromagnetic one through intermediate situations such as the quasi-electrostatic and quasi-dynamic regimes. Each configuration is defined by a particular set of equations which allows to clearly determine the individual role played by the electric and magnetic contribution in the generation of adiabatic compression. We notice that these findings can be applied for the realization of a THz nano-metric generator. © 2013 Optical Society of America.
Zhao, Yuanyang; Xiao, Jun; Li, Liansheng; Yang, Qichao; Liu, Guangbin; Wang, Le; Tang, Bin
2014-01-01
A method of compressor performance analysis under multiple working conditions is present based on the Time-weighted average (TWA). The main operation parameters can be obtained based the estimate of the working conditions and times of compressors. Then the comprehensive analysis method can be used to get the overall performance of compressor. The performance of a basic centrifugal compressor was simulation by CFD method in this paper. The overall performance of the centrifugal compressor is c...
DESIGN OF 8-4 AND 9-4 COMPRESSORS FORHIGH SPEED MULTIPLICATION
R. Marimuthu; Dhruv Bansal; Balamurugan, S.; P. S. Mallick
2013-01-01
This study presents higher order compressors which can be effectively used for high speed multiplications. The proposed compressors offer less delay and area. But the Energy Delay Product (EDP) is slightly higher than lower order compressors. The performance of 8Ã8, 16Ã16 and 24Ã24 multipliers using the proposed higher order compressors has been compared with the same multipliers using lower order compressors and found that the new structures can be used for high speed multiplications. These ...
Turbine Engine with Differential Gear Driven Fan and Compressor
Suciu, Gabriel L. (Inventor); Pagluica, Gino J. (Inventor); Duong, Loc Quang (Inventor); Portlock, Lawrence E. (Inventor)
2013-01-01
A gas turbine engine provides a differential gear system coupling the turbine to the bypass fan and the compressor. In this manner, the power/speed split between the bypass fan and the compressor can be optimized under all conditions. In the example shown, the turbine drives a sun gear, which drives a planet carrier and a ring gear in a differential manner. One of the planet carrier and the ring gear is coupled to the bypass fan, while the other is coupled to the compressor.
Design Method for Channel Diffusers of Centrifugal Compressors
Directory of Open Access Journals (Sweden)
Mykola Kalinkevych
2013-01-01
Full Text Available The design method for channel diffusers of centrifugal compressors, which is based on the solving of the inverse problem of gas dynamics, is presented in the paper. The concept of the design is to provide high pressure recovery of the diffuser by assuming the preseparation condition of the boundary layer along one of the channel surfaces. The channel diffuser was designed with the use of developed method to replace the vaned diffuser of the centrifugal compressor model stage. The numerical simulation of the diffusers was implemented by means of CFD software. Obtained gas dynamic characteristics of the designed diffuser were compared to the base vaned diffuser of the compressor stage.
Some field experience with subsynchronous vibration of centrifugal compressors
Wang, Xi-Xuan; Gu, Jin-Chu; Shen, Qin-Gen; Hua, Yong-Li; Zhu, Lan-Sheng; Du, Yun-Tian
1989-01-01
A lot of large chemical fertilizer plants producing 1000 ton NH3/day and 1700 ton urea/day were constructed in the 1970's in China. During operation, subsynchronous vibration takes place occasionally in some of the large turbine-compressor sets and has resulted in heavy economic losses. Two cases of subsynchronous vibration are described: Self-excited vibration of the low-pressure (LP) cylinder of one kind of N2-H2 multistage compressor; and Forced subsynchronous vibration of the high-pressure (HP) cylinder of the CO2 compressor.
Plasma Compression by a Magnetic Field in a Toroidal-Type Device
International Nuclear Information System (INIS)
The Tuman device, a racetrack, was built to study the adiabatic compression of a plasma column by an external magnetic field increasing with time, and was designed to carry out two-stage heating of the plasma. Magnetic compression is preceded by ohmic heating of the plasma under conditions analogous to those for the operation of Tokamak. During ohmic heating the longitudinal magnetic field is essentially non-uniform. In the curved toroidal sections the maximum quasi-stationary magnetic field is approximately 40 kOe, and in the straight parts 1 to 2 kOe. The glass discharge chamber, is a magnetic force tube, that is its cross section in the curved sections is 1/20th the cross section in the straight sections. The plasma must fill the force tube, whose dimensions are set by a diaphragm in the middle of the straight section and by the ratio of field intensities in the straight and curved sections. With our column configuration considerably more power can be introduced into the plasma than in a uniform torus. The plasma volume is approximately 15 1 when the plasma column is 250 cm long. Compression must be carried out by increasing the longitudinal magnetic field in the straight sections to 30 kOe. The field build-up time may vary from 30 to 250 μs. The plasma must be compressed in the wide, straight sections to approximately the same cross-section as in the curved sections. Compression reduces the volume of plasma by a factor of 10 to 20. All the tests were carried out with hydrogen at pressures from 1 x 10-3 to 5 x 10-2 Torr. The toroidal discharge was excited by a transformer. The duration of ohmic heating was 300 μs. The current in the plasma did not normally exceed 1 to 2 kA. With a quasi-stationary magnetic field of 1 to 2 kOe in the curved sections, plasma is obtained with a conductivity of (1 to 2) x 1014esu. Measurements of the diamagnetic moment of the plasma and microwave measurements showed that.when the magnetic field in the toroidal sections was
Energy Technology Data Exchange (ETDEWEB)
Han, Song; Yang, Helin [College of Physical Science and Technology, Central China Normal University, Wuhan (China); Cong, Lonqing; Singh, Ranjan [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore (Singapore); Centre for Disruptive Photonic Technologies, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore (Singapore); Gao, Fei [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore (Singapore)
2016-05-15
Toroidal multipoles have recently been explored in various scientific communities, ranging from atomic and molecular physics, electrodynamics, and solid-state physics to biology. Here we experimentally and numerically demonstrate a three-dimensional toroidal metamaterial where two different toroidal dipoles along orthogonal directions have been observed. The chosen toroidal metamaterial also simultaneously supports Fano resonance and the classical analog of electromagnetically induced transparency (EIT) phenomena in the transmission spectra that originate from the electric-toroidal dipole and electric-magnetic dipole destructive interference. The intriguing properties of the toroidal resonances may open up avenues for applications in toroidal moments generator, sensing and slow-light devices. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Retrofitting reciprocating compressors for noise control
International Nuclear Information System (INIS)
The Alberta Energy Resources Conservation Board recently enacted their noise control directive ID 88-1. The effects of this regulation on the operation of an oil and gas facility are discussed, and a specific case history is presented to provide a disciplined strategy for noise attenuation retrofits. An investigation was carried out into sound sources at a reciprocating compressor gas plant, revealing several sound sources: engine exhaust stacks, engine exhaust silencer shells, direct-drive fan cooler inlets, direct drive fan cooler outlets, aerial cooler inlets and aerial cooler outlets. Details are presented of the investigative techniques and order-ranking of sources by decibel level. When controlling engine exhaust noise, silencers or mufflers are the preferred treatment. Choice of type (reactive or absorptive) and specification of acoustical performance of a silencer are discussed. The gas plant achieved noise reductions of 6-13 dB, measured at affected residences, through the use of engine exhaust silencers. 4 figs., 2 tabs
Stabilized Liner Compressor: The Return of Linus
Turchi, Peter; Frese, Sherry; Frese, Michael; Mielke, Charles; Hinrichs, Mark; Nguyen, Doan
2015-11-01
To access the lower cost regime of magneto-inertial fusion at megagauss magnetic field-levels requires the use of dynamic conductors in the form of imploding cylindrical shells, aka, liners. Such liner implosions can compress magnetic flux and plasma to attain fusion conditions, but are subject to Rayleigh-Taylor instabilities, both in the launch and recovery of the liner material and in the final few diameters of implosion. These instabilities were overcome in the Linus program at the Naval Research Laboratory, c. 1979, providing the experimentally-demonstrated basis for repetitive operation and leading to an economical reactor concept at low fusion gain. The recent ARPA-E program for low-cost fusion technology has revived interest in this approach. We shall discuss progress in modeling and design of a Stabilized Liner Compressor (SLC) that extends the earlier work to higher pressures and liner speeds appropriate to potential plasma targets. Sponsored by ARPA-E ALPHA Program.
Integrated polarization rotator/converter by stimulated Raman adiabatic passage.
Xiong, Xiao; Zou, Chang-Ling; Ren, Xi-Feng; Guo, Guang-Can
2013-07-15
We proposed a polarization rotator inspired by stimulated Raman adiabatic passage model from quantum optics, which is composed of a signal waveguide and an ancillary waveguide. The two orthogonal modes in signal waveguide and the oblique mode in ancillary waveguide form a Λ-type three-level system. By controlling the width of signal waveguide and the gap between two waveguides, adiabatic conversion between two orthogonal modes can be realized in the signal waveguide. With such adiabatic passage, polarization conversion is completed within 150 μm length, with the efficiencies over 99% for both conversions between horizontal polarization and vertical polarization. In addition, such a polarization rotator is quite robust against fabrication error, allowing a wide range of tolerances for the rotator geometric parameters. Our work is not only significative to photonic simulations of coherent quantum phenomena with engineered photonic waveguides, but also enlightens the practical applications of these phenomena in optical device designs. PMID:23938558
Semiclassical approximations for adiabatic slow-fast systems
Teufel, Stefan
2012-01-01
In this letter we give a systematic derivation and justification of the semiclassical model for the slow degrees of freedom in adiabatic slow-fast systems first found by Littlejohn and Flynn [5]. The classical Hamiltonian obtains a correction due to the variation of the adiabatic subspaces and the symplectic form is modified by the curvature of the Berry connection. We show that this classical system can be used to approximate quantum mechanical expectations and the time-evolution of operators also in sub-leading order in the combined adiabatic and semiclassical limit. In solid state physics the corresponding semiclassical description of Bloch electrons has led to substantial progress during the recent years, see [1]. Here, as an illustration, we show how to compute the Piezo-current arising from a slow deformation of a crystal in the presence of a constant magnetic field.
Analysis and Simulation of Adiabatic Bend Transitions in Optical Fibers
Institute of Scientific and Technical Information of China (English)
YAO Lei; LOU Shu-Qin; JIAN Shui-Sheng
2009-01-01
A low-loss criterion for bend transitions in optical fibers is proposed. An optical fiber can be tightly bent with low loss to be adiabatic for the fundamental mode, provided that an approximate upper bound on the rate of change of bend curvature for a given bend curvature is satisfied. Two typical adiabatic bend transition paths, the optimum profile and linear profile, are analyzed and studied numerically. A realizable adiabatic transition with an Archimedean spiral profile is introduced for low bend loss in tightly bent optical fibers. Design of the transitions is based on modeling of the propagation and coupling characteristics of the core and cladding modes,which clearly illustrate the physical processes involved.
Adiabatic Quantum Computation is Equivalent to Standard Quantum Computation
Aharonov, D; Kempe, J; Landau, Z; Lloyd, S; Regev, O; Aharonov, Dorit; Dam, Wim van; Kempe, Julia; Landau, Zeph; Lloyd, Seth; Regev, Oded
2004-01-01
Adiabatic quantum computation has recently attracted attention in the physics and computer science communities, but its computational power has been unknown. We settle this question and describe an efficient adiabatic simulation of any given quantum algorithm, which implies that the adiabatic computation model and the conventional quantum circuit model are polynomially equivalent. Our result can be extended to the physically realistic setting of particles arranged on a two-dimensional grid with nearest neighbor interactions. The equivalence between the models provides a new vantage point from which to tackle the central issues in quantum computation, namely designing new quantum algorithms and constructing fault tolerant quantum computers. In particular, by translating the main open questions in quantum algorithms to the language of spectral gaps of sparse matrices, the result makes quantum algorithmic questions accessible to a wider scientific audience, acquainted with mathematical physics, expander theory a...
Adiabaticity and gravity theory independent conservation laws for cosmological perturbations
Romano, Antonio Enea; Sasaki, Misao
2015-01-01
We carefully study the implications of adiabaticity for the behavior of cosmological perturbations. There are essentially three similar but different definitions of non-adiabaticity: one is appropriate for a thermodynamic fluid $\\delta P_{nad}$, another is for a general matter field $\\delta P_{c,nad}$, and the last one is valid only on superhorizon scales. The first two definitions coincide if $c_s^2=c_w^2$ where $c_s$ is the propagation speed of the perturbation, while $c_w^2=\\dot P/\\dot\\rho$. Assuming the adiabaticity in the general sense, $\\delta P_{c,nad}=0$, we derive a relation between the lapse function in the comoving slicing $A_c$ and $\\delta P_{nad}$ valid for arbitrary matter field in any theory of gravity, by using only momentum conservation. The relation implies that as long as $c_s\
Global adiabaticity and non-Gaussianity consistency condition
Romano, Antonio Enea; Mooij, Sander; Sasaki, Misao
2016-10-01
In the context of single-field inflation, the conservation of the curvature perturbation on comoving slices, Rc, on super-horizon scales is one of the assumptions necessary to derive the consistency condition between the squeezed limit of the bispectrum and the spectrum of the primordial curvature perturbation. However, the conservation of Rc holds only after the perturbation has reached the adiabatic limit where the constant mode of Rc dominates over the other (usually decaying) mode. In this case, the non-adiabatic pressure perturbation defined in the thermodynamic sense, δPnad ≡ δP - cw2 δρ where cw2 = P ˙ / ρ ˙ , usually becomes also negligible on superhorizon scales. Therefore one might think that the adiabatic limit is the same as thermodynamic adiabaticity. This is in fact not true. In other words, thermodynamic adiabaticity is not a sufficient condition for the conservation of Rc on super-horizon scales. In this paper, we consider models that satisfy δPnad = 0 on all scales, which we call global adiabaticity (GA), which is guaranteed if cw2 = cs2 , where cs is the phase velocity of the propagation of the perturbation. A known example is the case of ultra-slow-roll (USR) inflation in which cw2 = cs2 = 1. In order to generalize USR we develop a method to find the Lagrangian of GA K-inflation models from the behavior of background quantities as functions of the scale factor. Applying this method we show that there indeed exists a wide class of GA models with cw2 = cs2, which allows Rc to grow on superhorizon scales, and hence violates the non-Gaussianity consistency condition.
Multi-point optimization of recirculation flow type casing treatment in centrifugal compressors
Tun, Min Thaw; Sakaguchi, Daisaku
2016-06-01
High-pressure ratio and wide operating range are highly required for a turbocharger in diesel engines. A recirculation flow type casing treatment is effective for flow range enhancement of centrifugal compressors. Two ring grooves on a suction pipe and a shroud casing wall are connected by means of an annular passage and stable recirculation flow is formed at small flow rates from the downstream groove toward the upstream groove through the annular bypass. The shape of baseline recirculation flow type casing is modified and optimized by using a multi-point optimization code with a metamodel assisted evolutionary algorithm embedding a commercial CFD code CFX from ANSYS. The numerical optimization results give the optimized design of casing with improving adiabatic efficiency in wide operating flow rate range. Sensitivity analysis of design parameters as a function of efficiency has been performed. It is found that the optimized casing design provides optimized recirculation flow rate, in which an increment of entropy rise is minimized at grooves and passages of the rotating impeller.
Quantum Adiabatic Pumping by Modulating Tunnel Phase in Quantum Dots
Taguchi, Masahiko; Nakajima, Satoshi; Kubo, Toshihiro; Tokura, Yasuhiro
2016-08-01
In a mesoscopic system, under zero bias voltage, a finite charge is transferred by quantum adiabatic pumping by adiabatically and periodically changing two or more control parameters. We obtained expressions for the pumped charge for a ring of three quantum dots (QDs) by choosing the magnetic flux penetrating the ring as one of the control parameters. We found that the pumped charge shows a steplike behavior with respect to the variance of the flux. The value of the step heights is not universal but depends on the trajectory of the control parameters. We discuss the physical origin of this behavior on the basis of the Fano resonant condition of the ring.
Adiabatic theory of ionization of atoms by intense laser pulses
International Nuclear Information System (INIS)
As a first step towards the adiabatic theory of ionization of atoms by intense laser pulses, here we consider the simplest one-dimensional zero-range potential model. The asymptotic solution to the time-dependent Schroedinger equation in the adiabatic regime is obtained and the photoelectron spectrum is calculated. The factorization formula for the photoelectron spectrum in the back-rescattering region, first suggested by Morishita et al. [Phys. Rev. Lett. 100, 013903 (2008)] on the basis of ab initio calculations, is derived analytically.
Microstructure evolution mechanism in adiabatic shear band in TA2
Institute of Scientific and Technical Information of China (English)
杨扬; 熊俊; 杨续跃
2004-01-01
The micro structure evolution mechanism in adiabatic shear band in commercial pure titanium (TA2) at high strain rates(γ≈105 - 106/s) were studied. The nanosized recrystallized grains (about 50 nm in diameter) within the center of adiabatic shear band (ASB) were observed by means of transmission electronic microscope (TEM). A Rotational Dynamic Recrystallization (RDR) mechanism can explain the microstructure evolution (i. e. nanosized grains were formed within 5 - 10μs) in ASB. Kinetics calculations indicate that the recrystallized small grains are formed during the deformation and don't undergo significant growth by grain boundary migration after deformation.
Non-adiabatic pumping through interacting quantum dots
Cavaliere, Fabio; Governale, Michele; König, Jürgen
2009-01-01
We study non-adiabatic two-parameter charge and spin pumping through a single-level quantum dot with Coulomb interaction. For the limit of weak tunnel coupling and in the regime of pumping frequencies up to the tunneling rates, $\\Omega \\lesssim \\Gamma/\\hbar$, we perform an exact resummation of contributions of all orders in the pumping frequency. As striking non-adiabatic signatures, we find frequency-dependent phase shifts in the charge and spin currents, which allow for an effective single-...
Nanoscale resolution for fluorescence microscopy via adiabatic passage
Rubio, Juan Luis; Ahufinger, Verònica; Mompart, Jordi
2015-01-01
We propose the use of the subwavelength localization via adiabatic passage technique for fluorescence microscopy with nanoscale resolution in the far field. This technique uses a {\\Lambda}-type medium coherently coupled to two laser pulses: the pump, with a node in its spatial profile, and the Stokes. The population of the {\\Lambda} system is adiabatically transferred from one ground state to the other except at the node position, yielding a narrow population peak. This coherent localization allows fluorescence imaging with nanometer lateral resolution. We derive an analytical expression to asses the resolution and perform a comparison with the coherent population trapping and the stimulated-emission-depletion techniques.
EFRC guidelines for vibrations in reciprocating compressor systems
Eijk, A.
2008-01-01
One of the disadvantages of a reciprocating compressor is that it generates pulsations and vibrations, which, without limitation and proper attention during design, manufacturing, installation and operation, can lead to fatigue failures, inefficiency, capacity limitations and unsafe situations. To j
A computer simulation study of compressor tuning phenomena
Nieter, J. J.; Singh, R.
1984-12-01
Basic thermofluid processes of a positive displacement compressor are strongly dependent upon the acoustic behavior of the manifolds. The tuning process of such a compressor is fairly complex as increases in the mass flow rate may not correspond with higher energy efficiencies. In this paper a computer simulation program is described, which includes the manifold back pressure effect, developed to investigate and explain the tuning phenomena for a single or two-cylinder reciprocating compressor. A symmetric suction manifold system for a two-cylinder refrigeration compressor has been considered as the example case in this tuning study. Results for flow efficiency, energy efficiency, and pressure pulsations at the valve exit are presented in terms of the acoustic natural frequencies of the manifold system. Predicted results compare reasonably well with experimental data. Based on this study, it is possible to choose optimal manifold dimensions which will provide higher efficiencies with lower pressure pulsations.
Compressor-fan unitary structure for air conditioning system
Dreiman, N.
2015-08-01
An extremely compact, therefore space saving unitary structure of short axial length is produced by radial integration of a revolving piston rotary compressor and an impeller of a centrifugal fan. The unitary structure employs single motor to run as the compressor so the airflow fan and eliminates duality of motors, related power supply and control elements. Novel revolving piston rotary compressor which provides possibility for such integration comprises the following: a suction gas delivery system which provides cooling of the motor and supplies refrigerant into the suction chamber under higher pressure (supercharged); a modified discharge system and lubricating oil supply system. Axial passages formed in the stationary crankshaft are used to supply discharge gas to a condenser, to return vaporized cooling agent from the evaporator to the suction cavity of the compressor, to pass a lubricant and to accommodate wiring supplying power to the unitary structure driver -external rotor electric motor.
Vapor Compressor Driven Hybrid Two-Phase Loop Project
National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project will demonstrate a vapor compressor driven hybrid two-phase loop technology. The hybrid two-phase loop...
Coatings for Fuel Cell Propulsion Compressor Bearings Project
National Aeronautics and Space Administration — Fuel cell air handling systems require clean and contaminant-free inlet air, which dictates that oil-free, motorized, compressor/expander systems should be used....
The performance of a linear compressor with triangle flexure bearings
Zhou, Wenjie; Wang, Longyi; Gan, Zhihua; Qiu, L. M.; Pfotenhauer, John
2012-06-01
This paper reports the performance of a self-fabricated moving coil linear compressor at Zhejiang University. The efficiency of this compressor is tested by an RC load method. From experimental results, its resonant frequency is below 30Hz. When combined with a pulse tube cryocooler (PTC) working at 40Hz, the minimum temperature is 49.1K; the cooling power at 80K is 4.5W, with 540W electricity power input. From the RC load experiment, the maximum efficiency of this compressor is only 37% at 21 Hz. Therefore, this compressor has the potential to drive a three stage PTC at liquid helium temperature by running at 25Hz or lower.
Axial flow, multi-stage turbine and compressor models
International Nuclear Information System (INIS)
Design models of multi-stage, axial-flow turbine and compressor are developed for high temperature nuclear reactor power plants with Closed Brayton Cycle for energy conversion. The models are based on a mean-line through-flow analysis for free-vortex flow, account for the profile, secondary, end wall, trailing edge and tip clearance losses in the cascades, and calculate the geometrical parameters of the blade cascades. The effects of the mean-stage work coefficient, flow coefficient and stage reaction on the design and performance of helium turbine and compressor are investigated. The results compare favorably with those reported for 6 stages helium turbine and 20 stages helium compressor. Also presented and discussed are the results of parametric analyses of a 530-MW helium turbine, and a 251-MW helium compressor.
Optimization of refrigeration system with gas-injected scroll compressor
Energy Technology Data Exchange (ETDEWEB)
Wang, Baolong; Shi, Wenxing; Han, Linjun; Li, Xianting [Department of Building Science, Tsinghua University, Beijing 100084 (China)
2009-11-15
Gas refrigerant injection has been proven as an effective method to improve the performance of the scroll compressor and its refrigeration system under high compression ratio working conditions. Much research on the injected scroll compressor and its system has been conducted, but the universal control and design method is still lacking. A model of the refrigeration system with a gas-injected scroll compressor is developed in this paper. With this model, the effects of gas injection on the system and component parameters are investigated. Based on the identified evaporator characteristics and thermodynamic analysis, a set of general principles for the design and operation of the refrigeration or heat pump system with a gas-injected scroll compressor is proposed. (author)
A Novel Aerodynamic Design Method for Centrifugal Compressor Impeller
Directory of Open Access Journals (Sweden)
Mahdi Nili-Ahmadabadi
2014-01-01
Full Text Available This paper describes a new quasi-3D design method for centrifugal compressor impeller. The method links up a novel inverse design algorithm, called Ball-Spine Algorithm (BSA, and a quasi-3D analysis. Euler equation is solved on the impeller meridional plane. The unknown boundaries (hub and shroud of numerical domain are iteratively modified by BSA until a target pressure distribution in flow passage is reached. To validate the quasi-3D analysis code, existing compressor impeller is investigated experimentally. Comparison between the quasi-3D analysis and the experimental results shows good agreement. Also, a full 3D Navier-Stokes code is used to analyze the existing and designed compressor numerically. The results show that the momentum decrease near the shroud wall in the existing compressor is removed by hub-shroud modifications resulting an improvement in performance by 0.6 percent.
A Novel Plasma-Based Compressor Stall Control System Project
National Aeronautics and Space Administration — Modern aircraft gas turbine engines utilize highly loaded airfoils in both the compressor and turbine to maximize performance while minimizing weight, cost, and...
Tailoring Inlet Flow to Enable High Accuracy Compressor Performance Measurements
Brossman, John R.; Smith, Natalie R.; Talalayev, Anton; Key, Nicole L.
2011-12-01
To accomplish the research goals of capturing the effects of blade row interactions on compressor performance, small changes in performance must be measurable. This also requires axi-symmetric flow so that measuring one passage accurately captures the phenomena occurring in all passages. Thus, uniform inlet flow is a necessity. The original front-driven compressor had non-uniform temperature at the inlet. Additional challenges in controlling shaft speed to within tight tolerances were associated with the use of a viscous fluid coupling. Thus, a new electric motor, with variable frequency drive speed control was implemented. To address the issues with the inlet flow, the compressor is now driven from the rear resulting in improved inlet flow uniformity. This paper presents the design choices of the new layout in addition to the preliminary performance data of the compressor and an uncertainty analysis.
Development Of A Centrifugal Hydrogen Pipeline Gas Compressor
Energy Technology Data Exchange (ETDEWEB)
Di Bella, Francis A. [Concepts NREC, White River Junction, VY (United States)
2015-04-16
Concepts NREC (CN) has completed a Department of Energy (DOE) sponsored project to analyze, design, and fabricate a pipeline capacity hydrogen compressor. The pipeline compressor is a critical component in the DOE strategy to provide sufficient quantities of hydrogen to support the expected shift in transportation fuels from liquid and natural gas to hydrogen. The hydrogen would be generated by renewable energy (solar, wind, and perhaps even tidal or ocean), and would be electrolyzed from water. The hydrogen would then be transported to the population centers in the U.S., where fuel-cell vehicles are expected to become popular and necessary to relieve dependency on fossil fuels. The specifications for the required pipeline hydrogen compressor indicates a need for a small package that is efficient, less costly, and more reliable than what is available in the form of a multi-cylinder, reciprocating (positive displacement) compressor for compressing hydrogen in the gas industry.
Adiabatic Compressed Air Energy Storage with packed bed thermal energy storage
International Nuclear Information System (INIS)
Highlights: • The paper presents a thermodynamic analysis of A-CAES using packed bed regenerators. • The packed beds are used to store the compression heat. • A numerical model is developed, validated and used to simulate system operation. • The simulated efficiencies are between 70.5% and 71.1% for continuous operation. • Heat build-up in the beds reduces continuous cycle efficiency slightly. - Abstract: The majority of articles on Adiabatic Compressed Air Energy Storage (A-CAES) so far have focussed on the use of indirect-contact heat exchangers and a thermal fluid in which to store the compression heat. While packed beds have been suggested, a detailed analysis of A-CAES with packed beds is lacking in the available literature. This paper presents such an analysis. We develop a numerical model of an A-CAES system with packed beds and validate it against analytical solutions. Our results suggest that an efficiency in excess of 70% should be achievable, which is higher than many of the previous estimates for A-CAES systems using indirect-contact heat exchangers. We carry out an exergy analysis for a single charge–storage–discharge cycle to see where the main losses are likely to transpire and we find that the main losses occur in the compressors and expanders (accounting for nearly 20% of the work input) rather than in the packed beds. The system is then simulated for continuous cycling and it is found that the build-up of leftover heat from previous cycles in the packed beds results in higher steady state temperature profiles of the packed beds. This leads to a small reduction (<0.5%) in efficiency for continuous operation
Experimental investigation of transitional flow in a toroidal pipe
Kühnen, J; Hof, B; Kuhlmann, H
2015-01-01
The flow instability and further transition to turbulence in a toroidal pipe (torus) with curvature (tube-to-coiling diameter) 0.049 is investigated experimentally. The flow inside the toroidal pipe is driven by a steel sphere fitted to the inner pipe diameter. The sphere is moved with constant azimuthal velocity from outside the torus by a moving magnet. The experiment is designed to investigate curved pipe flow by optical measurement techniques. Using stereoscopic particle image velocimetry, laser Doppler velocimetry and pressure drop measurements, the flow is measured for Reynolds numbers ranging from 1000 to 15000. Time- and space-resolved velocity fields are obtained and analysed. The steady axisymmetric basic flow is strongly influenced by centrifugal effects. On an increase of the Reynolds number we find a sequence of bifurcations. For Re=4075 a supercritical bifurcation to an oscillatory flow is found in which waves travel in the streamwise direction with a phase velocity slightly faster than the mean...
Stabilization of ballooning modes with sheared toroidal rotation
International Nuclear Information System (INIS)
A new code demonstrates the stabilization of MHD ballooning modes by sheared toroidal rotation. A shifted-circle model is used to elucidate the physics, and numerically reconstructed equilibria are used to analyze DIII-D discharges. In the ballooning representation, the modes shift periodically along the field line to the next point of unfavorable curvature. The shift frequency (dΩ/dq, where Ω is the angular toroidal velocity and q is the safety factor) is proportional to the rotation shear and inversely proportional to the magnetic shear. Stability improves with increasing shift frequency and, in the shifted circle model, direct stable access to the second stability regime occurs when this frequency is a fraction of the Alfven frequency, ωA = VA/qR. Shear stabilization is also demonstrated for an equilibrium reconstruction of a DIII-D VH-mode. (author). 9 refs, 3 figs
Cooling of Neutron Stars with Strong Toroidal Magnetic Fields
Page, D; Küker, M; Page, Dany; Geppert, Ulrich; Kueker, Manfred
2007-01-01
We present models of temperature distribution in the crust of a neutron star in the presence of a strong toroidal component superposed to the poloidal component of the magnetic field. The presence of such a toroidal field hinders heat flow toward the surface in a large part of the crust. As a result, the neutron star surface presents two warm regions surrounded by extended cold regions and has a thermal luminosity much lower than in the case the magnetic field is purely poloidal. We apply these models to calculate the thermal evolution of such neutron stars and show that the lowered photon luminosity naturally extends their life-time as detectable thermal X-ray sources.
Low-frequency fluctuations in a pure toroidal magnetized plasma
Indian Academy of Sciences (India)
P K Sharma; R Singh; D Bora
2009-12-01
A magnetized, low- plasma in pure toroidal configuration is formed and extensively studied with ion mass as control parameter. Xenon, krypton and argon plasmas are formed at a fixed toroidal magnetic field of 0.024 T, with a peak density of ∼ 1011 cm-3, ∼ 4 × 1010 cm-3 and ∼ 2 × 1010 cm−3 respectively. The experimental investigation of time-averaged plasma parameter reveals that their profiles remain insensitive to ion mass and suggests that saturated slab equilibrium is obtained. Low-frequency (LF) coherent fluctuations ( < ci) are observed and identified as flute modes. Here ci represents ion cyclotron frequency. Our results indicate that these modes get reduced with ion mass. The frequency of the fluctuating mode decreases with increase in the ion mass. Further, an attempt has been made to discuss the theory of flute modes to understand the relevance of some of our experimental observations.
An Overview of Plasma Confinement in Toroidal Systems
Dini, Fatemeh; Amrollahi, Reza; Khorasani, Sina
2009-01-01
This overview presents a tutorial introduction to the theory of magnetic plasma confinement in toroidal confinement systems with particular emphasis on axisymmetric equilibrium geometries, and tokamaks. The discussion covers three important aspects of plasma physics: Equilibrium, Stability, and Transport. The section on equilibrium will go through an introduction to ideal magnetohydrodynamics, curvilinear system of coordinates, flux coordinates, extensions to axisymmetric equilibrium, Grad-Shafranov Equation (GSE), Green's function formalism, as well as analytical and numerical solutions to GSE. The section on stability will address topics including Lyapunov Stability in nonlinear systems, energy principle, modal analysis, and simplifications for axisymmetric machines. The final section will consider transport in toroidal systems. We present the flux-surface-averaged system of equations describing classical and non-classical transport phenomena. Applications to the small-sized high-aspect-ratio Damavand tokam...
Toroidal AC transformer for beam intensity measurements in CSR
International Nuclear Information System (INIS)
The intensity of a pulsed beam of charged particles in the Cooling Storage Ring Project of Heavy Ion Research Facility in Lanzhou (HIRFL-CSR) will be measured with a toroidal current transformer. By comparing and analyzing the properties of kinds of magnetic cores, a strip wound toroidal core is adopted, which is made of a high-permeability alloy and can measure a pulsed beam with frequency range of 0.2 to 2 MHz. The permeability of Fe-based nanocrystalline alloy varying with frequency is measured and the noises in the circuit are analyzed. By adding a low-noise operational amplifier into the circuit, the current down to 1 μA can be detected
Reevaluation of the Braginskii viscous force for toroidal plasma
Johnson, Robert W.
2011-12-01
The model by Braginskii [1] (Braginskii, S. I. 1965 Transport processes in plasma. In: Review of Plasma Physics, Vol. 1 (ed. M.A. Leontovich). New York, NY: Consultants Bureau, pp. 205-311) for the viscous stress tensor is used to determine the shear and gyroviscous forces acting within a toroidally confined plasma. Comparison is made to a previous evaluation, which contains an inconsistent treatment of the radial derivative and neglects the effect of the pitch angle. Parallel viscosity contributes a radial shear viscous force, which may develop for sufficient vertical asymmetry to the ion velocity profile. An evaluation is performed of this radial viscous force for a tokamak near equilibrium, which indicates qualitative agreement between theory and measurement for impure plasma discharges with strong toroidal flow.
Nonlinear particle simulation of ion cyclotron waves in toroidal geometry
Energy Technology Data Exchange (ETDEWEB)
Kuley, A., E-mail: akuley@uci.edu; Lin, Z. [Department of Physics and Astronomy, University of California Irvine, CA-92697 (United States); Bao, J. [Fusion Simulation Center, Peking University, Beijing (China); Department of Physics and Astronomy, University of California Irvine, CA-92697 (United States); Wei, X. S.; Xiao, Y. [Institute of Fusion Theory and Simulation, Zhejiang University, Hangzhou (China)
2015-12-10
Global particle simulation model has been developed in this work to provide a first-principles tool for studying the nonlinear interactions of radio frequency (RF) waves with plasmas in tokamak. In this model, ions are considered as fully kinetic particles using the Vlasov equation and electrons are treated as guiding centers using the drift kinetic equation with realistic electron-to-ion mass ratio. Boris push scheme for the ion motion has been developed in the toroidal geometry using magnetic coordinates and successfully verified for the ion cyclotron and ion Bernstein waves in global gyrokinetic toroidal code (GTC). The nonlinear simulation capability is applied to study the parametric decay instability of a pump wave into an ion Bernstein wave side band and a low frequency ion cyclotron quasi mode.
ATLAS barrel toroid integration and test area in building 180
Maximilien Brice
2003-01-01
The ATLAS barrel toroid system consists of eight coils, each of axial length 25.3 m, assembled radially and symmetrically around the beam axis. The coils are of a flat racetrack type with two 'double-pancake' windings made of 20.5 kA aluminium-stabilized niobium-titanium superconductor. The barrel toroid is being assembled in building 180 on the Meyrin site. In the first phase of assembly, the coils are packed into their aluminium-alloy casing. These photos show the double-pancake coils from ANSALDO and the coil casings from ALSTOM. In the foreground is the tooling from COSMI used to turn over the coil casings during this first phase. In the right background is the yellow lifting gantry manufactured at JINR-Dubna, Russia which will transport the coil casings to a heating table for prestressing. Two test benches with magnetic mirror are also visible.
Counterformal contacts of full toroidal continuously variable transmission
Institute of Scientific and Technical Information of China (English)
ATTIA Nabil Abdulla; QIN Da-tong
2005-01-01
The point and the line contacts of a toroidal continuously variable transmission (CVT) are studied. The contact shapes between the roller and input and output disks are formulated by using the classical Hertz contact theory. Based on the formulated equations, different system factors affecting the maximum Hertz stress in the elliptical and strip contacts of the full toroidal CVT are explored, which include the properties of the contacting material (Young's modulus), operating condition (pushing load) and geometrical parameters (aspect cavity ratio, aspect roller ratio). The comparative results reveal the relations between the maximum Hertz stress and the speed ratio in the form of graphs. These graphs give useful information for designer to know the maximum Hertz stress during operation in such systems.
Quasars a supermassive rotating toroidal black hole interpretation
Spivey, R J
2000-01-01
A supermassive rotating toroidal black hole (TBH) is proposed as the fundamental structure of quasars and other jet-producing active galactic nuclei. Rotating protogalaxies gather matter from the central gaseous region leading to the birth of massive toroidal stars whose internal nuclear reactions proceed very rapidly. Once the nuclear fuel is spent, gravitational collapse produces a slender ring-shaped TBH remnant. These events are typically the first supernovae of the host galaxies. Given time the TBH mass increases through continued accretion by several orders of magnitude, the event horizon swells whilst the central aperture shrinks. The difference in angular velocities between the accreting matter and the TBH induces a magnetic field that is strongest in the region of the central aperture and innermost ergoregion. Due to the presence of negative energy states when such a gravitational vortex is immersed in an electromagnetic field, circumstances are near ideal for energy extraction via non-thermal radiat...
MINERVA: Ideal MHD stability code for toroidally rotating tokamak plasmas
Aiba, N.; Tokuda, S.; Furukawa, M.; Snyder, P. B.; Chu, M. S.
2009-08-01
A new linear MHD stability code MINERVA is developed for investigating a toroidal rotation effect on the stability of ideal MHD modes in tokamak plasmas. This code solves the Frieman-Rotenberg equation as not only the generalized eigenvalue problem but also the initial value problem. The parallel computing method used in this code realizes the stability analysis of both long and short wavelength MHD modes in short time. The results of some benchmarking tests show the validity of this MINERVA code. The numerical study with MINERVA about the toroidal rotation effect on the edge MHD stability shows that the rotation shear destabilizes the intermediate wavelength modes but stabilizes the short wavelength edge localized MHD modes, though the rotation frequency destabilizes both the long and the short wavelength MHD modes.
Compact toroid development. Resource needs for field reversed configurations
International Nuclear Information System (INIS)
This document contains the goals and technical approach for the five years 1985 to 1990 for the investigation of the properties of a magnetic configuration for plasma confinement identified as the field reversed configuration (FRC). The included material represents the third phase of FRC program planning. The first was reported in DOE/ER-0160: Compact Toroid Development, Status and Technical Needs, February 1983. The second was reported in DOE/ER-0197: Compact Toroid Development, Activity Plans for Field Reversed Configurations, June 1984. This planning identifies the facilities and resources needed to achieve the goals set forth in the first two phases. The information in this document is based on technical recommendations provided by the FRC community
Variable speed hermetic reciprocating compressors for domestic refrigerators
DEFF Research Database (Denmark)
Rasmussen, Bjarne D.
1998-01-01
This article describes the results of a both theoretical and experimental investigation of the performance of variable speed hermetic reciprocating compressors for domestic refrigerators. The investigation was performed as a part of a larger research project with the objective of reducing...... the energy consumption of domestic refrigerators by increasing the efficiency of the refrigeration system. The improvement of the system efficiency was to be obtained by introducing continuous operation and use variable speed compressors for controlling the capacity of the refrigeration system...