Simultaneous distribution of AC and DC power
Polese, Luigi Gentile
2015-09-15
A system and method for the transport and distribution of both AC (alternating current) power and DC (direct current) power over wiring infrastructure normally used for distributing AC power only, for example, residential and/or commercial buildings' electrical wires is disclosed and taught. The system and method permits the combining of AC and DC power sources and the simultaneous distribution of the resulting power over the same wiring. At the utilization site a complementary device permits the separation of the DC power from the AC power and their reconstruction, for use in conventional AC-only and DC-only devices.
AC distribution system for TFTR pulsed loads
International Nuclear Information System (INIS)
Carroll, R.F.; Ramakrishnan, S.; Lemmon, G.N.; Moo, W.I.
1977-01-01
This paper outlines the AC distribution system associated with the Tokamak Fusion Test Reactor and discusses the significant areas related to design, protection, and equipment selection, particularly where there is a departure from normal utility and industrial applications
SNS AC Power Distribution and Reliability of AC Power Supply
Holik, Paul S
2005-01-01
The SNS Project has 45MW of installed power. A design description under the Construction Design and Maintenance (CDM) with regard to regulations (OSHA, NFPA, NEC), reliability issues and maintenance of the AC power distribution system are herewith presented. The SNS Project has 45MW of installed power. The Accelerator Systems are Front End (FE)and LINAC KLYSTRON Building (LK), Central Helium Liquefier (CHL), High Energy Beam Transport (HEBT), Accumulator Ring and Ring to Target Beam Transport (RTBT) Support Buildings have 30MW installed power. FELK has 16MW installed, majority of which is klystron and magnet power supply system. CHL, supporting the super conducting portion of the accelerator has 7MW installed power and the RING Systems (HEBT, RING and RTBT) have also 7MW installed power.*
Regularization and error assignment to unfolded distributions
Zech, Gunter
2011-01-01
The commonly used approach to present unfolded data only in graphical formwith the diagonal error depending on the regularization strength is unsatisfac-tory. It does not permit the adjustment of parameters of theories, the exclusionof theories that are admitted by the observed data and does not allow the com-bination of data from different experiments. We propose fixing the regulariza-tion strength by a p-value criterion, indicating the experimental uncertaintiesindependent of the regularization and publishing the unfolded data in additionwithout regularization. These considerations are illustrated with three differentunfolding and smoothing approaches applied to a toy example.
Multi-phase AC/AC step-down converter for distribution systems
Aeloiza, Eddy C.; Burgos, Rolando P.
2017-10-25
A step-down AC/AC converter for use in an electric distribution system includes at least one chopper circuit for each one of a plurality of phases of the AC power, each chopper circuit including a four-quadrant switch coupled in series between primary and secondary sides of the chopper circuit and a current-bidirectional two-quadrant switch coupled between the secondary side of the chopper circuit and a common node. Each current-bidirectional two-quadrant switch is oriented in the same direction, with respect to the secondary side of the corresponding chopper circuit and the common node. The converter further includes a control circuit configured to pulse-width-modulate control inputs of the switches, to convert a first multiphase AC voltage at the primary sides of the chopper circuits to a second multiphase AC voltage at the secondary sides of the chopper circuits, the second multiphase AC voltage being lower in voltage than the first multiphase AC voltage.
Distributed cooperative control of AC microgrids
Bidram, Ali
In this dissertation, the comprehensive secondary control of electric power microgrids is of concern. Microgrid technical challenges are mainly realized through the hierarchical control structure, including primary, secondary, and tertiary control levels. Primary control level is locally implemented at each distributed generator (DG), while the secondary and tertiary control levels are conventionally implemented through a centralized control structure. The centralized structure requires a central controller which increases the reliability concerns by posing the single point of failure. In this dissertation, the distributed control structure using the distributed cooperative control of multi-agent systems is exploited to increase the secondary control reliability. The secondary control objectives are microgrid voltage and frequency, and distributed generators (DGs) active and reactive powers. Fully distributed control protocols are implemented through distributed communication networks. In the distributed control structure, each DG only requires its own information and the information of its neighbors on the communication network. The distributed structure obviates the requirements for a central controller and complex communication network which, in turn, improves the system reliability. Since the DG dynamics are nonlinear and non-identical, input-output feedback linearization is used to transform the nonlinear dynamics of DGs to linear dynamics. Proposed control frameworks cover the control of microgrids containing inverter-based DGs. Typical microgrid test systems are used to verify the effectiveness of the proposed control protocols.
Distributed AC power flow method for AC and AC-DC hybrid ...
African Journals Online (AJOL)
... on voltage level and R/X ratio in the formulation itself. DPFM is applied on a 10 bus, low voltage, microgrid system giving a better voltage profile.. Keywords: Microgrid (MG), Distributed Energy Resources (DER), Particle Swarm Optimization (OPF), Time varying inertia weight (TVIW), Distributed power flow method (DPFM) ...
Droop-free Distributed Control for AC Microgrids
DEFF Research Database (Denmark)
Nasirian, Vahidreza; Shafiee, Qobad; Guerrero, Josep M.
2016-01-01
A cooperative distributed secondary/primary control paradigm for AC microgrids is proposed. This solution replaces the centralized secondary control and the primary-level droop mechanism of each inverter with three separate regulators: voltage, reactive power, and active power regulators. A sparse...... guidelines are provided. Steady-state performance analysis shows that the proposed controller can accurately handle the global voltage regulation and proportional load sharing. An AC microgrid prototype is set up, where the controller performance, plug-and-play capability, and resiliency to the failure...
Regularized multivariate regression models with skew-t error distributions
Chen, Lianfu; Pourahmadi, Mohsen; Maadooliat, Mehdi
2014-01-01
We consider regularization of the parameters in multivariate linear regression models with the errors having a multivariate skew-t distribution. An iterative penalized likelihood procedure is proposed for constructing sparse estimators of both
Reduction of Nambu-Poisson Manifolds by Regular Distributions
Das, Apurba
2018-03-01
The version of Marsden-Ratiu reduction theorem for Nambu-Poisson manifolds by a regular distribution has been studied by Ibáñez et al. In this paper we show that the reduction is always ensured unless the distribution is zero. Next we extend the more general Falceto-Zambon Poisson reduction theorem for Nambu-Poisson manifolds. Finally, we define gauge transformations of Nambu-Poisson structures and show that these transformations commute with the reduction procedure.
Regularized κ-distributions with non-diverging moments
Scherer, K.; Fichtner, H.; Lazar, M.
2017-12-01
For various plasma applications the so-called (non-relativistic) κ-distribution is widely used to reproduce and interpret the suprathermal particle populations exhibiting a power-law distribution in velocity or energy. Despite its reputation the standard κ-distribution as a concept is still disputable, mainly due to the velocity moments M l which make a macroscopic characterization possible, but whose existence is restricted only to low orders l definition of the κ-distribution itself is conditioned by the existence of the moment of order l = 2 (i.e., kinetic temperature) satisfied only for κ > 3/2 . In order to resolve these critical limitations we introduce the regularized κ-distribution with non-diverging moments. For the evaluation of all velocity moments a general analytical expression is provided enabling a significant step towards a macroscopic (fluid-like) description of space plasmas, and, in general, any system of κ-distributed particles.
Regular distributive efficiency and the distributive liberal social contract.
Jean Mercier Ythier
2009-01-01
We consider abstract social systems of private property, made of n individuals endowed with non-paternalistic interdependent preferences, who interact through exchanges on competitive markets and Pareto-efficient lumpsum transfers. The transfers follow from a distributive liberal social contract defined as a redistribution of initial endowments such that the resulting market equilibrium allocation is, both, Pareto-efficient relative to individual interdependent preferences, and unanimously we...
Combined operation of AC and DC distribution system with distributed generation units
International Nuclear Information System (INIS)
Noroozian, R.; Abedi, M.; Gharehpetian, G.
2010-01-01
This paper presents a DC distribution system which has been supplied by external AC systems as well as local DG units in order to demonstrate an overall solution to power quality issue. In this paper, the proposed operation method is demonstrated by simulation of power transfer between external AC systems, DG units, AC and DC loads. The power flow control in DC distribution system has been achieved by network converters and DG converters. Also, the mathematical model of the network, DG and load converters are obtained by using the average technique, which allows converter systems accurately simulated and control strategies for this converters is achieved. A suitable control strategy for network converters has been proposed that involves DC voltage droop regulator and novel instantaneous power regulation scheme. Also, a novel control technique has been proposed for DG converters. In this paper, a novel control system based on stationary and synchronously rotating reference frame has been proposed for load converters for supplying AC loads connected to the DC bus by balanced voltages. The several case studies have been studied based on proposed methods. The simulation results show that DC distribution systems including DG units can improve the power quality at the point of common coupling (PCC) in the power distribution system or industrial power system. (authors)
Research on key technology of planning and design for AC/DC hybrid distribution network
Shen, Yu; Wu, Guilian; Zheng, Huan; Deng, Junpeng; Shi, Pengjia
2018-04-01
With the increasing demand of DC generation and DC load, the development of DC technology, AC and DC distribution network integrating will become an important form of future distribution network. In this paper, the key technology of planning and design for AC/DC hybrid distribution network is proposed, including the selection of AC and DC voltage series, the design of typical grid structure and the comprehensive evaluation method of planning scheme. The research results provide some ideas and directions for the future development of AC/DC hybrid distribution network.
Regularized multivariate regression models with skew-t error distributions
Chen, Lianfu
2014-06-01
We consider regularization of the parameters in multivariate linear regression models with the errors having a multivariate skew-t distribution. An iterative penalized likelihood procedure is proposed for constructing sparse estimators of both the regression coefficient and inverse scale matrices simultaneously. The sparsity is introduced through penalizing the negative log-likelihood by adding L1-penalties on the entries of the two matrices. Taking advantage of the hierarchical representation of skew-t distributions, and using the expectation conditional maximization (ECM) algorithm, we reduce the problem to penalized normal likelihood and develop a procedure to minimize the ensuing objective function. Using a simulation study the performance of the method is assessed, and the methodology is illustrated using a real data set with a 24-dimensional response vector. © 2014 Elsevier B.V.
Spine labeling in MRI via regularized distribution matching.
Hojjat, Seyed-Parsa; Ayed, Ismail; Garvin, Gregory J; Punithakumar, Kumaradevan
2017-11-01
This study investigates an efficient (nearly real-time) two-stage spine labeling algorithm that removes the need for an external training while being applicable to different types of MRI data and acquisition protocols. Based solely on the image being labeled (i.e., we do not use training data), the first stage aims at detecting potential vertebra candidates following the optimization of a functional containing two terms: (i) a distribution-matching term that encodes contextual information about the vertebrae via a density model learned from a very simple user input, which amounts to a point (mouse click) on a predefined vertebra; and (ii) a regularization constraint, which penalizes isolated candidates in the solution. The second stage removes false positives and identifies all vertebrae and discs by optimizing a geometric constraint, which embeds generic anatomical information on the interconnections between neighboring structures. Based on generic knowledge, our geometric constraint does not require external training. We performed quantitative evaluations of the algorithm over a data set of 90 mid-sagittal MRI images of the lumbar spine acquired from 45 different subjects. To assess the flexibility of the algorithm, we used both T1- and T2-weighted images for each subject. A total of 990 structures were automatically detected/labeled and compared to ground-truth annotations by an expert. On the T2-weighted data, we obtained an accuracy of 91.6% for the vertebrae and 89.2% for the discs. On the T1-weighted data, we obtained an accuracy of 90.7% for the vertebrae and 88.1% for the discs. Our algorithm removes the need for external training while being applicable to different types of MRI data and acquisition protocols. Based on the current testing data, a subject-specific model density and generic anatomical information, our method can achieve competitive performances when applied to T1- and T2-weighted MRI images.
Distributed Control for Autonomous Operation of a Three-Port AC/DC/DS Hybrid Microgrid
DEFF Research Database (Denmark)
Wang, Peng; Jin, Chi; Zhu, Dexuan
2015-01-01
This paper presents a distributed control scheme for reliable autonomous operation of a hybrid three-port ac/dc/distributed storage (ds) microgrid by means of power sharing in individual network, power exchange between ac and dc networks, and power management among three networks. The proposed...... distributed control scheme includes: 1) a fully decentralized control, which is achieved by local power sharing (LPS) in individual ac or dc network, global power sharing (GPS) throughout ac/dc networks, and storage power sharing (SPS) among distributed storages. Upon fully decentralized control, each power...... module can operate independently without communication links. This would benefit for riding through communication malfunction in multilayer supervision control system; 2) a multilevel power exchange control for scheduling LPS, GPS, and SPS has been developed to reduce unnecessary power exchange between...
International Nuclear Information System (INIS)
Olson, Gordon L.
2008-01-01
In binary stochastic media in two- and three-dimensions consisting of randomly placed impenetrable disks or spheres, the chord lengths in the background material between disks and spheres closely follow exponential distributions if the disks and spheres occupy less than 10% of the medium. This work demonstrates that for regular spatial structures of disks and spheres, the tails of the chord length distributions (CLDs) follow power laws rather than exponentials. In dilute media, when the disks and spheres are widely spaced, the slope of the power law seems to be independent of the details of the structure. When approaching a close-packed arrangement, the exact placement of the spheres can make a significant difference. When regular structures are perturbed by small random displacements, the CLDs become power laws with steeper slopes. An example CLD from a quasi-random distribution of spheres in clusters shows a modified exponential distribution
Energy Technology Data Exchange (ETDEWEB)
Olson, Gordon L. [Computer and Computational Sciences Division (CCS-2), Los Alamos National Laboratory, 5 Foxglove Circle, Madison, WI 53717 (United States)], E-mail: olson99@tds.net
2008-11-15
In binary stochastic media in two- and three-dimensions consisting of randomly placed impenetrable disks or spheres, the chord lengths in the background material between disks and spheres closely follow exponential distributions if the disks and spheres occupy less than 10% of the medium. This work demonstrates that for regular spatial structures of disks and spheres, the tails of the chord length distributions (CLDs) follow power laws rather than exponentials. In dilute media, when the disks and spheres are widely spaced, the slope of the power law seems to be independent of the details of the structure. When approaching a close-packed arrangement, the exact placement of the spheres can make a significant difference. When regular structures are perturbed by small random displacements, the CLDs become power laws with steeper slopes. An example CLD from a quasi-random distribution of spheres in clusters shows a modified exponential distribution.
n value and Jc distribution dependence of AC transport current losses in HTS conductors
International Nuclear Information System (INIS)
Ogawa, Jun; Sawai, Yusuke; Nakayama, Haruki; Tsukamoto, Osami; Miyagi, Daisuke
2004-01-01
Compared with LTS materials, HTS materials have some peculiarities affecting AC loss characteristics of the conductors. We measured the AC transport current losses in YBCO thin film coated conductors and a Bi2223/Ag sheathed tape. Comparing the measured data with analytical calculations, the dependence of the AC transport current losses on the n value and critical current density distributions are studied. It is shown that, considering the n values and J c distributions, the peculiarities in the HTS materials can be taken into consideration and the transport current losses in HTS conductors can be calculated by the same analytical method used for LTS
Study of Power Flow Algorithm of AC/DC Distribution System including VSC-MTDC
Directory of Open Access Journals (Sweden)
Haifeng Liang
2015-08-01
Full Text Available In recent years, distributed generation and a large number of sensitive AC and DC loads have been connected to distribution networks, which introduce a series of challenges to distribution network operators (DNOs. In addition, the advantages of DC distribution networks, such as the energy conservation and emission reduction, mean that the voltage source converter based multi-terminal direct current (VSC-MTDC for AC/DC distribution systems demonstrates a great potential, hence drawing growing research interest. In this paper, considering losses of the reactor, the filter and the converter, a mathematical model of VSC-HVDC for the load flow analysis is derived. An AC/DC distribution network architecture has been built, based on which the differences in modified equations of the VSC-MTDC-based network under different control modes are analyzed. In addition, corresponding interface functions under five control modes are provided, and a back/forward iterative algorithm which is applied to power flow calculation of the AC/DC distribution system including VSC-MTDC is proposed. Finally, by calculating the power flow of the modified IEEE14 AC/DC distribution network, the efficiency and validity of the model and algorithm are evaluated. With various distributed generations connected to the network at appropriate locations, power flow results show that network losses and utilization of transmission networks are effectively reduced.
Lim, Yeerang; Lee, Wonsuk; Bang, Hyochoong; Lee, Hosung
2017-04-01
A thrust distribution approach is proposed in this paper for a variable thrust solid propulsion system with an attitude control system (ACS) that uses a reduced number of nozzles for a three-axis attitude maneuver. Although a conventional variable thrust solid propulsion system needs six ACS nozzles, this paper proposes a thrust system with four ACS nozzles to reduce the complexity and mass of the system. The performance of the new system was analyzed with numerical simulations, and the results show that the performance of the system with four ACS nozzles was similar to the original system while the mass of the whole system was simultaneously reduced. Moreover, a feasibility analysis was performed to determine whether a thrust system with three ACS nozzles is possible.
Distributed energy resources in grid interactive AC microgrids
DEFF Research Database (Denmark)
Wang, Xiongfei; Guerrero, Josep; Chen, Zhe
2010-01-01
Increased penetration of distributed energy resources (DER) and large-scale deployment of renewable energy sources are challenging the entire architecture of traditional power system. Microgrid, featuring higher flexibility and reliability, becomes an attractive candidate for the configuration...
A Sufficient Condition on Convex Relaxation of AC Optimal Power Flow in Distribution Networks
DEFF Research Database (Denmark)
Huang, Shaojun; Wu, Qiuwei; Wang, Jianhui
2016-01-01
This paper proposes a sufficient condition for the convex relaxation of AC Optimal Power Flow (OPF) in radial distribution networks as a second order cone program (SOCP) to be exact. The condition requires that the allowed reverse power flow is only reactive or active, or none. Under the proposed...... solution of the SOCP can be converted to an optimal solution of the original AC OPF. The efficacy of the convex relaxation to solve the AC OPF is demonstrated by case studies of an optimal multi-period planning problem of electric vehicles (EVs) in distribution networks....... sufficient condition, the feasible sub-injection region (power injections of nodes excluding the root node) of the AC OPF is convex. The exactness of the convex relaxation under the proposed condition is proved through constructing a group of monotonic series with limits, which ensures that the optimal...
International Nuclear Information System (INIS)
Motozawa, Masaaki; Ito, Takahiro; Iwamoto, Kaoru; Kawashima, Hideki; Ando, Hirotomo; Senda, Tetsuya; Tsuji, Yoshiyuki; Kawaguchi, Yasuo
2013-01-01
Highlights: • Flow over the regularly distributed triangular ribs was investigated. • Simultaneous measurement of flow resistance and velocity profile was performed. • Flow resistance was measured directly and velocity profile was measured by LDV. • Flow resistance was estimated by the information of the velocity field. • Estimated flow resistance has good agreement with the measured flow resistance. -- Abstract: The relationship between the flow resistance of a turbulent flow over triangular ribs regularly distributed on a wall surface and the velocity distribution around the ribs was investigated experimentally. A concentric cylinder device composed of an inner test cylinder and an outer cylinder was employed to measure the flow resistance using the torque of the shaft of the inner cylinder and the velocity distribution of the flow around a rib by laser Doppler velocimetry (LDV) simultaneously. We prepared four inner test cylinders having 4, 8, 12 and 16 triangular ribs on the surface with the same interval between them. Each rib had an isosceles right triangle V-shape and a height of 2 mm. To investigate the relationship between flow resistance and velocity distribution, we estimated the frictional drag and pressure drag acting on the surface of the ribs separately using the velocity distribution. Therefore, we could also estimate the total flow resistance using the velocity distribution. As a result of the experiment, the flow resistance and the attachment point downstream of the rib were shown to depend on the distance between ribs. Moreover, the flow resistance estimated using the velocity distribution had good agreement with the flow resistance measured using the torque of the inner cylinder
Equalization Algorithm for Distributed Energy Storage Systems in Islanded AC Microgrids
DEFF Research Database (Denmark)
Aldana, Nelson Leonardo Diaz; Hernández, Adriana Carolina Luna; Quintero, Juan Carlos Vasquez
2015-01-01
This paper presents a centralized strategy for equalizing the state of charge of distributed energy storage systems in an islanded ac microgrid. The strategy is based on a simple algorithm denoted as equalization algorithm, which modifies the charge or discharge ratio on the time, for distributed...
Droop-free Team-oriented Control for AC Distribution Systems
DEFF Research Database (Denmark)
Nasirian, Vahidreza; Shafiee, Qobad; Guerrero, Josep M.
2015-01-01
Droop control is conventionally used for load sharing in AC distribution systems. Despite decentralized nature of the droop technique, it requires centralized secondary control to provide voltage and frequency regulation across the system. Distributed control, as an alternative to the centralized...
Distribution of AC loss in a HTS magnet for SMES with different operating conditions
Energy Technology Data Exchange (ETDEWEB)
Xu, Y., E-mail: xuyinghust@163.com [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, R and D Center of Applied Superconductivity, Huazhong University of Science and Technology, Wuhan 430074 (China); Tang, Y.; Ren, L.; Jiao, F. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, R and D Center of Applied Superconductivity, Huazhong University of Science and Technology, Wuhan 430074 (China); Song, M.; Cao, K.; Wang, D. [Yunnan Electric Power Research Institute, Kunming City 650217 (China); Wang, L.; Dong, H. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, R and D Center of Applied Superconductivity, Huazhong University of Science and Technology, Wuhan 430074 (China)
2013-11-15
Highlights: •We present a model to calculate the distribution of AC loss for a storage magnet. •Comparative analysis of AC loss with different operating conditions has done. •The nonuniform distribution factor “d” is proposed to estimate the inhomogeneity of a storage magnet. •The model predicts the loss distribution and crucial areas which are suffering from the high AC loss. This is significant for the conduction-cooled structure design. -- Abstract: The AC loss induced in superconducting tape may affect the performance of a superconducting device applied to power system, such as transformer, cable, motor and even Superconducting Magnetic Energy Storage (SMES). The operating condition of SMES is changeable due to the need of compensation to the active or reactive power according to the demand of a power grid. In this paper, it is investigated that the distribution of AC loss for a storage magnet on different operating conditions, which is based on finite element method (FEM) and measured properties of BSCCO/Ag tapes. This analytical method can be used to optimize the SMES magnet.
DEFF Research Database (Denmark)
Li, Chendan; Coelho, Ernane Antônio Alves; Dragicevic, Tomislav
2017-01-01
In this paper, a multiagent-based distributed control algorithm has been proposed to achieve state of charge (SoC) balance of distributed energy storage (DES) units in an ac microgrid. The proposal uses frequency scheduling instead of adaptive droop gain to regulate the active power. Each DES unit...
Ma, Qian; Xia, Houping; Xu, Qiang; Zhao, Lei
2018-05-01
A new method combining Tikhonov regularization and kernel matrix optimization by multi-wavelength incidence is proposed for retrieving particle size distribution (PSD) in an independent model with improved accuracy and stability. In comparison to individual regularization or multi-wavelength least squares, the proposed method exhibited better anti-noise capability, higher accuracy and stability. While standard regularization typically makes use of the unit matrix, it is not universal for different PSDs, particularly for Junge distributions. Thus, a suitable regularization matrix was chosen by numerical simulation, with the second-order differential matrix found to be appropriate for most PSD types.
Regularities of the vertical distribution of uranium-molybdenum mineralization
International Nuclear Information System (INIS)
Konstantinov, V.M.; Kazantsev, V.V.; Protasov, V.N.
1980-01-01
The geological structure of one of ore fields of the uranium-molybdenum formation pertaining to the northern framing of a large volcano-tectonic depression is studied. The main uranium deposits are related to necks formed by neck facies of brown liparites. Three zones are singled out within the limits of the ore field. In the upper one there are small ore bodies with a low uranium content represented by phenolite-chlorite, pitchblende 3-coffinite 3-jordizite and calcinite-sulphide associations, in the middle one - the main ore bodies formed by pitchblende 1-chlorite, molybdenite 2 (jordizite)-pitchblende 2-hydromica, coffinite 2-pyrite associations; in the lower one-thin veinlets formed by coffinite-molybdenite 1-chlorite, brannerite-pyrite and pitchblende 1-chlorite associations. Dimensions of the ore deposits depend on the neck sizes: in small necks the middle zone and, rarely, the lower one are of the industrial interest; in the large ones - the upper middle and, probably, lower ones. The regularities found can be extended to other deposits of the uranium-molybdenum formation [ru
Reconfigurable DC Links for Restructuring Existing Medium Voltage AC Distribution Grids
Shekhar, A.; Ramirez Elizondo, L.M.; Feng, Xianyong; Kontos, E.; Bauer, P.
2018-01-01
While the scientific community recognizes the benefits of DC power transfer, the distribution network operators point out the practical and economic constraints in refurbishing the existing AC network at a medium-voltage level. Some apprehensions like reliability, cost of ownership, and safety in
Three-Phase AC Optimal Power Flow Based Distribution Locational Marginal Price: Preprint
Energy Technology Data Exchange (ETDEWEB)
Yang, Rui; Zhang, Yingchen
2017-05-17
Designing market mechanisms for electricity distribution systems has been a hot topic due to the increased presence of smart loads and distributed energy resources (DERs) in distribution systems. The distribution locational marginal pricing (DLMP) methodology is one of the real-time pricing methods to enable such market mechanisms and provide economic incentives to active market participants. Determining the DLMP is challenging due to high power losses, the voltage volatility, and the phase imbalance in distribution systems. Existing DC Optimal Power Flow (OPF) approaches are unable to model power losses and the reactive power, while single-phase AC OPF methods cannot capture the phase imbalance. To address these challenges, in this paper, a three-phase AC OPF based approach is developed to define and calculate DLMP accurately. The DLMP is modeled as the marginal cost to serve an incremental unit of demand at a specific phase at a certain bus, and is calculated using the Lagrange multipliers in the three-phase AC OPF formulation. Extensive case studies have been conducted to understand the impact of system losses and the phase imbalance on DLMPs as well as the potential benefits of flexible resources.
AC losses in a type II superconductor strip with inhomogeneous critical current distribution
International Nuclear Information System (INIS)
Tsukamoto, Osami
2005-01-01
Analytical formulae derived by Brandt and Indenbom (1993 Phys. Rev. B 48 12893-906) and Norris (1970 J. Phys. D: Appl. Phys. 3 489-507) are often used to calculate the magnetization and AC transport current losses in HTS strip conductors, respectively. In these formulae, homogeneous distribution of critical sheet current density σ c in the strip is assumed. However, it is considered that σ c distributions are inhomogeneous in actual HTS strips and that the inhomogeneous σ c distributions cause deviations of the measured AC loss data of actual HTS strips from those formulae. A semi-analytical method to calculate AC transport current and magnetization losses is derived for a type II superconductor strip with inhomogeneous distribution of σ c in the direction of the strip width. The method is derived modifying the analysis of Brandt et al. The validity of the semi-analytical method is shown by comparing the results calculated by this method with those calculated by the Norris and Brandt formulae and by a different method of our previous work and also with experimental data. Moreover, it is shown that the deviation of the measured data from the Norris and Brandt models can be estimated by assuming proper σ c distributions
Regularization and asymptotic expansion of certain distributions defined by divergent series
Directory of Open Access Journals (Sweden)
Ricardo Estrada
1995-01-01
Full Text Available The regularization of the distribution ∑n=−∞∞δ(x−pn. which gives a regularized value to the divergent series ∑n=−∞∞φ(pn is obtained in several spaces of test functions. The asymptotic expansion as ϵ→0+of series of the type ∑n=0∞φ(ϵ pn is also obtained.
A Multi-Functional Fully Distributed Control Framework for AC Microgrids
DEFF Research Database (Denmark)
Shafiee, Qobad; Nasirian, Vahidreza; Quintero, Juan Carlos Vasquez
2018-01-01
This paper proposes a fully distributed control methodology for secondary control of AC microgrids. The control framework includes three modules: voltage regulator, reactive power regulator, and active power/frequency regulator. The voltage regulator module maintains the average voltage of the mi......This paper proposes a fully distributed control methodology for secondary control of AC microgrids. The control framework includes three modules: voltage regulator, reactive power regulator, and active power/frequency regulator. The voltage regulator module maintains the average voltage...... of the microgrid distribution line at the rated value. The reactive power regulator compares the local normalized reactive power of an inverter with its neighbors’ powers on a communication graph and, accordingly, fine-tunes Q-V droop coefficients to mitigate any reactive power mismatch. Collectively, these two....../reactive power sharing. An AC microgrid is prototyped to experimentally validate the proposed control methodology against the load change, plug-and-play operation, and communication constraints such as delay, packet loss, and limited bandwidth....
DEFF Research Database (Denmark)
Chaudhary, Sanjay; Guerrero, Josep M.; Teodorescu, Remus
2015-01-01
The development of distributed generation system and electric vehicles is bound to strain the distribution network. A typical radial distribution feeder suffers from the voltage fluctuation and feeder overload in the presence of a large amount of variable renewable generation. This paper presents...... a concept of enhancing the power handling capacity of distribution networks using dc grid interconnections. Control of both the active and reactive power exchange between the ac feeder and the interconnecting power converter has been proposed for the voltage regulation at the ac feeder terminal. Besides......, the dc grid interconnection also allows the introduction of a common storage system which can be shared by the connected ac feeders, and the dc grid connection to other renewable energy resources. The increased power handling capacity and improved voltage profile of the ac distribution feeder using...
DEFF Research Database (Denmark)
Mikosch, Thomas Valentin; Rackauskas, Alfredas
2010-01-01
In this paper, we deal with the asymptotic distribution of the maximum increment of a random walk with a regularly varying jump size distribution. This problem is motivated by a long-standing problem on change point detection for epidemic alternatives. It turns out that the limit distribution...... of the maximum increment of the random walk is one of the classical extreme value distributions, the Fréchet distribution. We prove the results in the general framework of point processes and for jump sizes taking values in a separable Banach space...
Control of Power Converters in AC Microgrids
DEFF Research Database (Denmark)
Rocabert, Joan; Luna, Alvaro; Blaabjerg, Frede
2012-01-01
The enabling of ac microgrids in distribution networks allows delivering distributed power and providing grid support services during regular operation of the grid, as well as powering isolated islands in case of faults and contingencies, thus increasing the performance and reliability of the ele......The enabling of ac microgrids in distribution networks allows delivering distributed power and providing grid support services during regular operation of the grid, as well as powering isolated islands in case of faults and contingencies, thus increasing the performance and reliability...
Stored Energy Balance for Distributed PV-Based Active Generators in an AC Microgrid
DEFF Research Database (Denmark)
Aldana, Nelson Leonardo Diaz; Wu, Dan; Dragicevic, Tomislav
2015-01-01
In this paper, a decentralized strategy based on fuzzy logic is proposed for balancing the state of charge of the energy storage units for distributed PV-based active generators. The proposed method, weights the action of conventional droop control loops for privileging the charge of the energy...... expandable and can be applied to a several number of power generators interconnected in a microgrid. Frequency and voltage bus signaling is used in order to coordinate the control operation mode between units. Simulation results in a low-voltage, three-phase, islanded AC microgrid show the feasibility...... of the proposed method and its applicability even for several active generators....
International Nuclear Information System (INIS)
Kang Zili.
1989-01-01
Based on summing up Guangxi geotectonic features and evolutionary regularities, this paper discusses the occurrence features, formation conditions and time-space distribution regularities of various U-rich strata during the development of geosyncline, platform and diwa stages, Especially, during diwa stage all those U-rich strata might be reworked to a certain degree and resulted in the mobilization of uranium, then enriching to form polygenetic composite uranium ore deposits with stratabound features. This study will be helpful for prospecting in the region
Maier, K H; Grawe, H; Kluge, H
1981-01-01
The g-factor measurements of the ground state and an isomeric level in /sup 217/Ac using the DPAD method with alpha -decay are described. The results of gamma -ray g-factor measurements for the isomer and a tentative decay scheme produced by alpha - gamma and gamma - gamma coincidence experiments are also presented. An analysis of the alpha - particle angular distributions suggests that nuclear deformation affects the observed anisotropy. (13 refs).
A Communication-Less Distributed Voltage Control Strategy for a Multi-Bus AC Islanded Microgrid
DEFF Research Database (Denmark)
Wang, Yanbo; Tan, Yongdong; Chen, Zhe
2014-01-01
This paper presents a communication-less distributed voltage control strategy for a multi-bus AC islanded microgrid. First, a Kalman Filter-based network voltage estimator is proposed to obtain voltage responses without communication links in the presence of load disturbances. Then, a voltage...... and reliability is improved for islanded microgrids due to communication-less operation. The simulations and experimental results are presented to validate the proposed distributed voltage control strategy....... optimal controller using MPC (Model Predictive Control) are developed to implement voltage optimal control. The contributions of this paper are demonstrated: (1) The proposed voltage estimator can dynamically obtain network voltage responses just through local voltage and current associated with each DG...
DEFF Research Database (Denmark)
Li, Chendan; Savaghebi, Mehdi; Guerrero, Josep M.
2016-01-01
on the power rating of the power converters. With various primary source for the distributed generator (DG), factors that are closely related to the operation cost, such as fuel cost of the generators and losses should be taken into account in order to improve the efficiency of the whole system. In this paper......, a multiagent-based distributed method is proposed to minimize the operation cost in AC microgrids. In the microgrid, each DG is acting as an agent which regulates the power individually using a novel power regulation method based on frequency scheduling. An optimal power command is obtained through carefully...... designed consensus algorithm by using sparse communication links only among neighbouring agents. Experimental results for different cases verified that the proposed control strategy can effectively reduce the operation cost....
Quasi-regular impurity distribution driven by charge-density wave
International Nuclear Information System (INIS)
Baldea, I.; Badescu, M.
1991-09-01
The displacive motion of the impurity distribution immersed into the one-dimensional system has recently been studied in detail as one kind of quasi-regularity driven by CDW. As a further investigation of this problem we develop here a microscopical model for a different kind of quasi-regular impurity distribution driven by CDW, consisting of the modulation in the probability of occupied sites. The dependence on impurity concentration and temperature of relevant CDW quantities is obtained. Data reported in the quasi-1D materials NbSe 3 and Ta 2 NiSe 7 (particularly, thermal hysteresis effects at CDW transition) are interpreted in the framework of the present model. Possible similarities to other physical systems are also suggested. (author). 38 refs, 7 figs
Some regularity of the grain size distribution in nuclear fuel with controllable structure
International Nuclear Information System (INIS)
Loktev, Igor
2008-01-01
It is known, the fission gas release from ceramic nuclear fuel depends from average size of grains. To increase grain size they use additives which activate sintering of pellets. However, grain size distribution influences on fission gas release also. Fuel with different structures, but with the same average size of grains has different fission gas release. Other structure elements, which influence operational behavior of fuel, are pores and inclusions. Earlier, in Kyoto, questions of distribution of grain size for fuel with 'natural' structure were discussed. Some regularity of grain size distribution of fuel with controllable structure and high average size of grains are considered in the report. Influence of inclusions and pores on an error of the automated definition of parameters of structure is shown. The criterion, which describe of behavior of fuel with specific grain size distribution, is offered
Directory of Open Access Journals (Sweden)
Chendan Li
2016-09-01
Full Text Available Recently, microgrids are attracting increasing research interest as promising technologies to integrate renewable energy resources into the distribution system. Although many works have been done on droop control applied to microgrids, they mainly focus on achieving proportional power sharing based on the power rating of the power converters. With various primary source for the distributed generator (DG, factors that are closely related to the operation cost, such as fuel cost of the generators and losses should be taken into account in order to improve the efficiency of the whole system. In this paper, a multiagent-based distributed method is proposed to minimize the operation cost in AC microgrids. In the microgrid, each DG is acting as an agent which regulates the power individually using a novel power regulation method based on frequency scheduling. An optimal power command is obtained through carefully designed consensus algorithm by using sparse communication links only among neighbouring agents. Experimental results for different cases verified that the proposed control strategy can effectively reduce the operation cost.
Directory of Open Access Journals (Sweden)
Zhuoya Zhao
2016-07-01
Full Text Available Crystal (Cry proteins derived from Bacillus thuringiensis (Bt have been widely used in transgenic crops due to their toxicity against insect pests. However, the distribution and metabolism of these toxins in insect tissues and organs have remained obscure because the target insects do not ingest much toxin. In this study, several Cry1Ac-resistant strains of Helicoverpa armigera, fed artificial diets containing high doses of Cry1Ac toxin, were used to investigate the distribution and metabolism of Cry1Ac in their bodies. Cry1Ac was only detected in larvae, not in pupae or adults. Also, Cry1Ac passed through the midgut into other tissues, such as the hemolymph and fat body, but did not reach the larval integument. Metabolic tests revealed that Cry1Ac degraded most rapidly in the fat body, followed by the hemolymph, peritrophic membrane and its contents. The toxin was metabolized slowly in the midgut, but was degraded in all locations within 48 h. These findings will improve understanding of the functional mechanism of Bt toxins in target insects and the biotransfer and the bioaccumulation of Bt toxins in arthropod food webs in the Bt crop ecosystem.
Research on stress distribution regularity of cement sheaths of radial well based on ABAQUS
Shi, Jihui; Cheng, Yuanfang; Li, Xiaolong; Xiao, Wen; Li, Menglai
2017-12-01
To ensure desirable outcome of hydraulic fracturing based on ultra-short radius radial systems, it is required to investigate the stress distribution regularity and stability of the cement sheath. On the basis of the theoretical model of the cement sheath stress distribution, a reservoir mechanical model was built using the finite element software, ABAQUS, according to the physical property of a certain oil reservoir of the Shengli oilfield. The stress distribution of the casing-cement-sheath-formation system under the practical condition was simulated, based on which analyses were conducted from multiple points of view. Results show that the stress on the internal interface of the cement sheath exceeds that on the external interface, and fluctuates with higher amplitudes, which means that the internal interface is the most failure-prone. The unevenness of the cement sheath stress distribution grows with the increasing horizontal principal stress ratio, and so does the variation magnitude. This indicates that higher horizontal principal stress ratios are unfavourable for the structural stability of the cement sheath. Both the wellbore quantity of the URRS and the physical property of the material can affect the cement sheath distribution. It is suggested to optimize the quantity of the radial wellbore and use cement with a lower elastic modulus and higher Poisson’s ratio. At last, the impact level of the above factor was analysed, with the help of the grey correlation analysis.
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Zeyan Lv
2018-04-01
Full Text Available This paper proposes a distributed coordination control for multiple bidirectional power converters (BPCs in a hybrid AC/DC microgrid with consideration of state-of-charge (SOC of storages. The researched hybrid AC/DC microgrid is composed of both AC and DC subgrids connected by multiple parallel BPCs. In the literature, the storages of a hybrid microgrid are considered to allocate in only the AC subgrid or DC subgrid, which reduces the reliability of the whole system, especially during the islanded mode. Besides, the SOC management has not been considered in BPCs’ operating strategy. This paper considers a hybrid microgrid topology which has energy storages in both AC side and DC side. This ensures the reliability while increasing the complexity of the control strategy at the same time. Further, a distributed coordination control method for multiple BPCs based on SOC was proposed to enhance the reliability of hybrid microgrid. Finally, the performance of the proposed control methods was verified by real-time hardware-in-loop (HIL tests.
International Nuclear Information System (INIS)
Soussaline, F.; Bidaut, L.; Raynaud, C.; Le Coq, G.
1983-06-01
An analytical solution to the SPECT reconstruction problem, where the actual attenuation effect can be included, was developped using a regularizing iterative method (RIM). The potential of this approach in quantitative brain studies when using a tracer for cerebrovascular disorders is now under evaluation. Mathematical simulations for a distributed activity in the brain surrounded by the skull and physical phantom studies were performed, using a rotating camera based SPECT system, allowing the calibration of the system and the evaluation of the adapted method to be used. On the simulation studies, the contrast obtained along a profile, was less than 5%, the standard deviation 8% and the quantitative accuracy 13%, for a uniform emission distribution of mean = 100 per pixel and a double attenuation coefficient of μ = 0.115 cm -1 and 0.5 cm -1 . Clinical data obtained after injection of 123 I (AMPI) were reconstructed using the RIM without and with cerebrovascular diseases or lesion defects. Contour finding techniques were used for the delineation of the brain and the skull, and measured attenuation coefficients were assumed within these two regions. Using volumes of interest, selected on homogeneous regions on an hemisphere and reported symetrically, the statistical uncertainty for 300 K events in the tomogram was found to be 12%, the index of symetry was of 4% for normal distribution. These results suggest that quantitative SPECT reconstruction for brain distribution is feasible, and that combined with an adapted tracer and an adequate model physiopathological parameters could be extracted
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M. P. Sulzer
2004-01-01
Full Text Available We report the observation and analysis of ionization flashes associated with the decay of meteoroids (so-called head echos detected by the Arecibo 430 MHz radar during regular ionospheric observations in the spring and autumn equinoxes. These two periods allow pointing well-above and nearly-into the ecliptic plane at dawn when the event rate maximizes. The observation of many thousands of events allows a statistical interpretation of the results, which show that there is a strong tendency for the observed meteoroids to come from the apex as has been previously reported (Chau and Woodman, 2004. The velocity distributions agree with Janches et al. (2003a when they are directly comparable, but the azimuth scan used in these observations allows a new perspective. We have constructed a simple statistical model which takes meteor velocities as input and gives radar line of sight velocities as output. The intent is to explain the fastest part of the velocity distribution. Since the speeds interpreted from the measurements are distributed fairly narrowly about nearly 60 km s-1, double the speed of the earth in its orbit, is consistent with the interpretation that many of the meteoroids seen by the Arecibo radar are moving in orbits about the sun with similar parameters as the earth, but in the retrograde direction. However, it is the directional information obtained from the beam-swinging radar experiment and the speed that together provide the evidence for this interpretation. Some aspects of the measured velocity distributions suggest that this is not a complete description even for the fast part of the distribution, and it certainly says nothing about the slow part first described in Janches et al. (2003a. Furthermore, we cannot conclude anything about the entire dust population since there are probably selection effects that restrict the observations to a subset of the population.
DEFF Research Database (Denmark)
Mikosch, Thomas Valentin; Moser, Martin
2013-01-01
We investigate the maximum increment of a random walk with heavy-tailed jump size distribution. Here heavy-tailedness is understood as regular variation of the finite-dimensional distributions. The jump sizes constitute a strictly stationary sequence. Using a continuous mapping argument acting...... on the point processes of the normalized jump sizes, we prove that the maximum increment of the random walk converges in distribution to a Fréchet distributed random variable....
Fu, Qiang; Su, Zhixin; Cheng, Yuqiang; Wang, Zhaofei; Li, Shiyu; Wang, Heng'an; Sun, Jianhe; Yan, Yaxian
In order to investigate the diverse characteristics of clustered, regularly interspaced short palindromic repeat (CRISPR) arrays and the distribution of virulence factor genes in avian Escherichia coli, 80 E. coli isolates obtained from chickens with avian pathogenic E. coli (APEC) or avian fecal commensal E. coli (AFEC) were identified. Using the multiplex polymerase chain reaction (PCR), five genes were subjected to phylogenetic typing and examined for CRISPR arrays to study genetic relatedness among the strains. The strains were further analyzed for CRISPR loci and virulence factor genes to determine a possible association between their CRISPR elements and their potential virulence. The strains were divided into five phylogenetic groups: A, B1, B2, D and E. It was confirmed that two types of CRISPR arrays, CRISPR1 and CRISPR2, which contain up to 246 distinct spacers, were amplified in most of the strains. Further classification of the isolates was achieved by sorting them into nine CRISPR clusters based on their spacer profiles, which indicates a candidate typing method for E. coli. Several significant differences in invasion-associated gene distribution were found between the APEC isolates and the AFEC isolates. Our results identified the distribution of 11 virulence genes and CRISPR diversity in 80 strains. It was demonstrated that, with the exception of iucD and aslA, there was no sharp demarcation in the gene distribution between the pathogenic (APEC) and commensal (AFEC) strains, while the total number of indicated CRISPR spacers may have a positive correlation with the potential pathogenicity of the E. coli isolates. Copyright © 2016. Published by Elsevier Masson SAS.
Variations and Regularities in the Hemispheric Distributions in Sunspot Groups of Various Classes
Gao, Peng-Xin
2018-05-01
The present study investigates the variations and regularities in the distributions in sunspot groups (SGs) of various classes in the northern and southern hemispheres from Solar Cycles (SCs) 12 to 23. Here, we use the separation scheme that was introduced by Gao, Li, and Li ( Solar Phys. 292, 124, 2017), which is based on A/U ( A is the corrected area of the SG, and U is the corrected umbral area of the SG), in order to separate SGs into simple SGs (A/U ≤ 4.5) and complex SGs (A/U > 6.2). The time series of Greenwich photoheliographic results from 1875 to 1976 (corresponding to complete SCs 12 - 20) and Debrecen photoheliographic data during the period 1974 - 2015 (corresponding to complete SCs 21 - 23) are used to show the distributions of simple and complex SGs in the northern and southern hemispheres. The main results we obtain are reported as follows: i) the larger of the maximum annual simple SG numbers in the two hemispheres and the larger of the maximum annual complex SG numbers in the two hemispheres occur in different hemispheres during SCs 12, 14, 18, and 19; ii) the relative changing trends of two curves - cumulative SG numbers in the northern and southern hemispheres - for simple SGs are different from those for complex SGs during SCs 12, 14, 18, and 21; and iii) there are discrepancies between the dominant hemispheres of simple and complex SGs for SCs 12, 14, 18, and 21.
DEFF Research Database (Denmark)
Han, Renke; Meng, Lexuan; Ferrari-Trecate, Giancarlo
2017-01-01
This paper offers a highly flexible and reliable control strategy to achieve voltage bounded regulation and accurate reactive power sharing coordinately in AC Micro-Grids. A containment and consensus-based distributed coordination controller is proposed, by which each output voltage magnitude can...... be bounded within a reasonable range and the accurate reactive power sharing among distributed generators can be also achieved. Combined with the two proposed controllers and electrical part of the AC Micro-Grid, a small signal model is fully developed to analyze the sensitivity of different control...... parameters. The effectiveness of the proposed controller in case of load variation, communication failure, plug-and-play capability are verified by the experimental setup as an islanded Micro-Grid....
International Nuclear Information System (INIS)
Lee, Chung ho; Xu, Fan; Jung, Cheolsoo
2014-01-01
Highlights: • TFB can enhance the rate performance of high voltage capacitors. • TFB can suppress to increase the discharge slope to improve the cell performance. • TFB decreases the charge transfer resistance of an AC cell. • TFB affects the distribution of the electrolyte components near the microporous AC. - Abstract: This paper presents a method to enhance the rate performance of high voltage capacitors using an electrolyte additive, 1,3,5-trifluorobenzene (TFB). With increasing discharge rate, the capacity of the activated carbon (AC)/lithium (Li) cell decreases with increasing the slope of the discharge curve and its potential drop at 4.6 V. By adding TFB, the discharge slope improves to increase the rate performance of the cell, and EIS showed that the charge transfer resistance (Rc) of the AC cell decreases. These results suggest that TFB affects the distribution of the electrolyte components near the microporous AC and improves the rate performance of the AC cell
An estimator-based distributed voltage-predictive control strategy for ac islanded microgrids
DEFF Research Database (Denmark)
Wang, Yanbo; Chen, Zhe; Wang, Xiongfei
2015-01-01
This paper presents an estimator-based voltage predictive control strategy for AC islanded microgrids, which is able to perform voltage control without any communication facilities. The proposed control strategy is composed of a network voltage estimator and a voltage predictive controller for each...... and has a good capability to reject uncertain perturbations of islanded microgrids....
Energy Distribution of a Regular Black Hole Solution in Einstein-Nonlinear Electrodynamics
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I. Radinschi
2015-01-01
Full Text Available A study about the energy momentum of a new four-dimensional spherically symmetric, static and charged, regular black hole solution developed in the context of general relativity coupled to nonlinear electrodynamics is presented. Asymptotically, this new black hole solution behaves as the Reissner-Nordström solution only for the particular value μ=4, where μ is a positive integer parameter appearing in the mass function of the solution. The calculations are performed by use of the Einstein, Landau-Lifshitz, Weinberg, and Møller energy momentum complexes. In all the aforementioned prescriptions, the expressions for the energy of the gravitating system considered depend on the mass M of the black hole, its charge q, a positive integer α, and the radial coordinate r. In all these pseudotensorial prescriptions, the momenta are found to vanish, while the Landau-Lifshitz and Weinberg prescriptions give the same result for the energy distribution. In addition, the limiting behavior of the energy for the cases r→∞, r→0, and q=0 is studied. The special case μ=4 and α=3 is also examined. We conclude that the Einstein and Møller energy momentum complexes can be considered as the most reliable tools for the study of the energy momentum localization of a gravitating system.
Some regularities in the distribution of kenophytes in the Polish Carpathians and their foreland
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Zając Maria
2015-03-01
Full Text Available The Polish Carpathians and their northern foreland are a rewarding object for the kenophyte distribution research. The study, using the cartogram method, showed that the number of kenophyte species decreases with increasing altitude. Only few kenophytes were found in the lower forest zone. This regularity concerns also the species that reach higher altitudes in the mountains of their native lands. A number of species migrated into the Carpathians through rivers and streams. River valleys generate many open habitats, which are easily colonized by kenophytes due to the lack of competition. In the Carpathians, towns used to be founded in the mountain valleys and this was also a favouring factor of kenophyte propagation. The arrangement of mountain ranges in the Polish Carpathians, including their foreland, hindered the migration of some species and allowed to discover the possible migration routes into the area covered by research. Tracing these migration routes was possible only for those species that have not occupied the whole available area yet. Additionally, the study indicated the most dangerous invasive species in the Polish Carpathians and their foreland.
Active Distribution Grid Management based on Robust AC Optimal Power Flow
DEFF Research Database (Denmark)
Soares, Tiago; Bessa, Richard J.; Pinson, Pierre
2017-01-01
Further integration of distributed renewable energy sources in distribution systems requires a paradigm change in grid management by the distribution system operators (DSO). DSOs are currently moving to an operational planning approach based on activating flexibility from distributed energy resou...
Reali, Florencia; Griffiths, Thomas L.
2009-01-01
The regularization of linguistic structures by learners has played a key role in arguments for strong innate constraints on language acquisition, and has important implications for language evolution. However, relating the inductive biases of learners to regularization behavior in laboratory tasks can be challenging without a formal model. In this…
Bearingless AC Homopolar Machine Design and Control for Distributed Flywheel Energy Storage
Severson, Eric Loren
The increasing ownership of electric vehicles, in-home solar and wind generation, and wider penetration of renewable energies onto the power grid has created a need for grid-based energy storage to provide energy-neutral services. These services include frequency regulation, which requires short response-times, high power ramping capabilities, and several charge cycles over the course of one day; and diurnal load-/generation-following services to offset the inherent mismatch between renewable generation and the power grid's load profile, which requires low self-discharge so that a reasonable efficiency is obtained over a 24 hour storage interval. To realize the maximum benefits of energy storage, the technology should be modular and have minimum geographic constraints, so that it is easily scalable according to local demands. Furthermore, the technology must be economically viable to participate in the energy markets. There is currently no storage technology that is able to simultaneously meet all of these needs. This dissertation focuses on developing a new energy storage device based on flywheel technology to meet these needs. It is shown that the bearingless ac homopolar machine can be used to overcome key obstacles in flywheel technology, namely: unacceptable self-discharge and overall system cost and complexity. Bearingless machines combine the functionality of a magnetic bearing and a motor/generator into a single electromechanical device. Design of these machines is particularly challenging due to cross-coupling effects and trade-offs between motor and magnetic bearing capabilities. The bearingless ac homopolar machine adds to these design challenges due to its 3D flux paths requiring computationally expensive 3D finite element analysis. At the time this dissertation was started, bearingless ac homopolar machines were a highly immature technology. This dissertation advances the state-of-the-art of these machines through research contributions in the areas of
DEFF Research Database (Denmark)
Li, Chendan; Firoozabadi, Mehdi Savaghebi; Quintero, Juan Carlos Vasquez
2015-01-01
sharing based on the power rating. With various types of distributed generator (DG) units in the system, factors that closely related to the operation cost, such as fuel cost and efficiencies of the generator should be taken into account in order to improve the efficiency of the whole system....... In this paper, a multiagent based distributed method is proposed to minimize operation cost of the AC microgrid. Each DG is acting as an agent which regulates the power individually using proposed frequency scheduling method. Optimal power command is obtained through carefully designed consensus algorithm...... with only light communication between neighboring agents. Case studies verified that the proposed control strategy can effectively reduce the operation cost....
International Nuclear Information System (INIS)
Favale, Nicolas O.; Sterin Speziale, Norma B.; Fernandez Tome, Maria C.
2007-01-01
Lamin A/C is the most studied nucleoskeletal constituent. Lamin A/C expression indicates cell differentiation and is also a structural component of nuclear speckles, which are involved in gene expression regulation. Hypertonicity has been reported to induce renal epithelial cell differentiation and expression of TonEBP (NFAT5), a transcriptional activator of hypertonicity-induced gene transcription. In this paper, we investigate the effect of hypertonicity on lamin A/C expression in MDCK cells and the involvement of TonEBP. Hypertonicity increased lamin A/C expression and its distribution to nucleoplasm with speckled pattern. Microscopy showed codistribution of TonEBP and lamin A/C in nucleoplasmic speckles, and immunoprecipitation demonstrated their interaction. TonEBP silencing caused lamin A/C redistribution from nucleoplasmic speckles to the nuclear rim, followed by lamin decrease, thus showing that hypertonicity induces lamin A/C speckles through a TonEBP-dependent mechanism. We suggest that lamin A/C speckles could serve TonEBP as scaffold thus favoring its role in hypertonicity
Directory of Open Access Journals (Sweden)
Tamrazyan Ashot Georgievich
2012-10-01
Full Text Available Accurate and adequate description of external influences and of the bearing capacity of the structural material requires the employment of the probability theory methods. In this regard, the characteristic that describes the probability of failure-free operation is required. The characteristic of reliability means that the maximum stress caused by the action of the load will not exceed the bearing capacity. In this paper, the author presents a solution to the problem of calculation of structures, namely, the identification of reliability of pre-set design parameters, in particular, cross-sectional dimensions. If the load distribution pattern is available, employment of the regularities of distributed functions make it possible to find the pattern of distribution of maximum stresses over the structure. Similarly, we can proceed to the design of structures of pre-set rigidity, reliability and stability in the case of regular load distribution. We consider the element of design (a monolithic concrete slab, maximum stress S which depends linearly on load q. Within a pre-set period of time, the probability will not exceed the values according to the Poisson law. The analysis demonstrates that the variability of the bearing capacity produces a stronger effect on relative sizes of cross sections of a slab than the variability of loads. It is therefore particularly important to reduce the coefficient of variation of the load capacity. One of the methods contemplates the truncation of the bearing capacity distribution by pre-culling the construction material.
Design of coolant distribution system (CDS) for ITER PF AC/DC converter
Energy Technology Data Exchange (ETDEWEB)
Guo, Bin [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Song, Zhiquan, E-mail: zhquansong@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Fu, Peng; Xu, Xuesong; Li, Chuan [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Wang, Min; Dong, Lin [China International Nuclear Fusion Energy Program Execution Center, Beijing 100862 (China)
2016-10-15
Highlights: • System process and arrangement has been proposed to meet the multiple requirements from the converter system. • Thermal hydraulic analysis model has been developed to size and predict the system operation behavior. • Prototype test has been performed to validate the proposed design methodology. - Abstract: The Poloidal Field (PF) converter unit, playing an essential role in the plasma shape and position control in vertical and horizontal direction, which is an important part of ITER power supply system. As an important subsystem of the converter unit, the coolant distribution system has the function to distribute the cooling water from ITER component cooling water system (CCWS) to its main components at the required flow rate, pressure and temperature. This paper presents the thermal hydraulic design of coolant distribution system for the ITER PF converter unit. Different operational requirements of the PF converter unit regarding flow rate, temperature and pressure have been analyzed to design the system process and arrangement. A thermal-hydraulic analysis model has been built to size the system and predict the flow rate and temperature distribution of the system under the normal operation. Based on the system thermal-hydraulic analysis results, the system pressure profile has been plotted to evaluate the pressure behavior along each client flow path. A CDS prototype for the ITER PF converter has been constructed and some experiments have been performed on it. A good agreement of the flow distribution and temperature behavior between the simulated and test results validate the proposed design methodology.
Prot, Olivier; SantolíK, OndřEj; Trotignon, Jean-Gabriel; Deferaudy, Hervé
2006-06-01
An entropy regularization algorithm (ERA) has been developed to compute the wave-energy density from electromagnetic field measurements. It is based on the wave distribution function (WDF) concept. To assess its suitability and efficiency, the algorithm is applied to experimental data that has already been analyzed using other inversion techniques. The FREJA satellite data that is used consists of six spectral matrices corresponding to six time-frequency points of an ELF hiss-event spectrogram. The WDF analysis is performed on these six points and the results are compared with those obtained previously. A statistical stability analysis confirms the stability of the solutions. The WDF computation is fast and without any prespecified parameters. The regularization parameter has been chosen in accordance with the Morozov's discrepancy principle. The Generalized Cross Validation and L-curve criterions are then tentatively used to provide a fully data-driven method. However, these criterions fail to determine a suitable value of the regularization parameter. Although the entropy regularization leads to solutions that agree fairly well with those already published, some differences are observed, and these are discussed in detail. The main advantage of the ERA is to return the WDF that exhibits the largest entropy and to avoid the use of a priori models, which sometimes seem to be more accurate but without any justification.
AC/DC Smart Control And Power Sharing of DC Distribution Systems
2012-02-10
ISRCS 2011, Boise, Idaho, USA, Pages 89-84, IEEE Xplore DOI 10.1109/ISRCS.2011.6016095, Aug 9-11, 2011. 8. A. Mohamed, M. Elshaer and O. A...Manooth, “A Survey of Systems to Integrate Distributed Energy Resources and Energy Storage on the Utility Grid,” in IEEE 2008 Energy 2030 Conf., 2008...Georgia, USA. [2] H. Puttgen, P. MacGregor, F. Lambert, “Distributed Generation: Semantic Hype or the Dawn of a New Era,” IEEE Power and Energy
DEFF Research Database (Denmark)
Nielsen, Jimmi; Jacobsen, Torben
2010-01-01
the primary current distribution to the DC current distribution restricted to the Three-Phase-Boundary (TPB) zone introduces an error in the determination of the reaction resistance, Rreac = Z(freq. → 0) − Z(freq. → ∞). The error is estimated for different width of the effective TPB zone and a rule of thumb...... regarding its significance is provided. The associated characteristic impedance spectrum shape change is simulated and its origin discussed. Furthermore, the characteristic shape of impedance spectra of thin electroceramic film electrodes with lateral ohmic resistance is studied as a function...
Comparative analysis of AC DC Microgrids for the Saudi Arabian distribution system
Qaseem, A.; Babar, M.; Danish Maqbool, S.; Al-Ammar, E.A.
2012-01-01
A Microgrid is a devised grouping of loads, generation sources and energy storage interfaced through fast response power electronics to form a small scale power network. The paper discusses the complexities that could be faced by the existing Saudi Arabian Grid when Distributed Generation Resources
DEFF Research Database (Denmark)
Missov, Trifon I.; Schöley, Jonas
to this criterion admissible distributions are, for example, the gamma, the beta, the truncated normal, the log-logistic and the Weibull, while distributions like the log-normal and the inverse Gaussian do not satisfy this condition. In this article we show that models with admissible frailty distributions...... and a Gompertz baseline provide a better fit to adult human mortality data than the corresponding models with non-admissible frailty distributions. We implement estimation procedures for mixture models with a Gompertz baseline and frailty that follows a gamma, truncated normal, log-normal, or inverse Gaussian...
International Nuclear Information System (INIS)
Bumba, V.; Hejna, L.
1988-01-01
From the comparison of several modes of time development of the latitudinal distribution of solar magnetic fields, obtained by different authors using different basic observational material and different methods, the following results were obtained: At high solar latitudes (|φ|> or ∼ 40deg) all distributions agree irrespective of the method of construction. In zones of activity around the solar equator, there is a qualitatively good but quantitatively poor agreement of the integrated, directly observed fields (from Mt. Wilson Observatory) and of the highly integrated fields derived from Hα synoptic charts. The mode of field distribution at high latitudes, more uniform and unipolar, is probably different from the field distribution at low latitudes where the more concentrated leading polarity occupies practically the same area as the less concentrated following polarity fields, if they are highly integrated. The large difference between Makarov's distribution and other modes of distribution seems to be natural if we take the method of construction into account, and very probably represents its close relationship with the smaller magnetic field elements connected with newer activity, while the other types of distribution demonstrate larger-scale, redistributed, older fields. The areas covered by the positive and negative polarities on the whole Sun during the investigated one and a half solar cycles (No 20 and 21) are practically equal. (author). 5 figs., 10 refs
Distributed control of hybrid AC microgrids with dynamic active and reactive power capacity tuning
DEFF Research Database (Denmark)
Nutkani, Inam Ullah; Loh, Poh Chiang; Blaabjerg, Frede
2012-01-01
Microgrids comprise of emerging generation technologies such as fuel cell, solar PV, wind turbine generator, storage and loads. They can, in principle, operate at different voltages and frequencies. Tying them either to the mains grid or among themselves would certainly require some interlinking...... power converters, whose control should preferably be done autonomously without demanding communication links. This paper proposes distributed control for power management between two Microgrids interlinked through inverters. The control scheme aims to reduce the reactive power loading stress on DERs...... and also allows active power transfer from overloaded grid to under- loaded grid. The performance of proposed control has been verified in simulation and through a scaled-down experimental system....
Adaptive Curtailment Plan with Energy Storage for AC/DC Combined Distribution Systems
Directory of Open Access Journals (Sweden)
Seungmin Jung
2016-08-01
Full Text Available For developing a large-scale combined system with a number of distributed resources, an appropriate compensation strategy based on the system components and changeable condition must be configured to handle the characteristics of the internal systems. Since renewable sources generate various fluctuations, the compensation plans for the storage device connected along with the sources should be supported by a precise expectation method. A cooperative strategy involving the sharing of the DC section with environmentally sensitive generators, like photovoltaic system (PVs or waves, demands appropriate ESS compensation solutions, owing to its complexity. An active power-control algorithm with voltage-expectation based on the DC power flow is introduced in this paper and is applied in the designed case studies performed on the electromagnetic transient simulation. DC based multi-generation system is composed by applying tidal generator and super capacitor. To utilize wind energy, an offshore wind–wave generation system was utilized in the verification process.
Distributivity of the algebra of regular open subsets of .beta. R / R
Czech Academy of Sciences Publication Activity Database
Balcar, Bohuslav; Hrušák, M.
2005-01-01
Roč. 149, č. 1 (2005), s. 1-7 ISSN 0166-8641 R&D Projects: GA ČR(CZ) GA201/03/0933; GA ČR(CZ) GA201/02/0857 Institutional research plan: CEZ:AV0Z10190503 Keywords : distributivity of Boolean algebras * cardinal invariants of the continuum * Čech-Stone compactification Subject RIV: BA - General Mathematics Impact factor: 0.297, year: 2005
General regularities of Sr 90 distribution in system soil-plant under natural conditions
International Nuclear Information System (INIS)
Gudeliene, I.; Marchiulioniene, D.; Petroshius, R.
2006-01-01
Sr 90 distribution in system 'soil - underground part of plant - aboveground part of plant' was investigated. It was determined that Sr 90 activity concentration in underground and aboveground part of plants and in mosses was not dependent on its activity concentration in soil. There was direct dependence of Sr 90 activity concentration in aboveground on underground parts of plants. Sr 90 transfer factor from soil to underground part of plants and mosses was directly dependent on this radionuclide activity concentration in them. (authors)
Study of regularities of distributing powdered dietetic additives in coarse dispersed foodstuffs
Directory of Open Access Journals (Sweden)
M. Pogozhikh
2017-12-01
Full Text Available An important intervention in the composition of food products is enrichment of food with micronutrients. In this regard, the authors investigated how the additive with the corresponding trace element will be distributed in the food product, and in this case, in minced meat, in order to meet the human needs for microelements.Micronutrient deficiencies have a significant impact on the nutritional status and health of the population in well developed and developing countries. These deficiencies cause a delay in the growth of children, various diseases, mortality, brain damage, reduced cognitive capacity and the ability of people of all ages. The global scale of micronutrient deficiencies in dietary intakes, in particular the lack of trace elements, has led to the development of powdered dietary supplements containing essential elements that enrich the coarse-type food products to increase their nutritional value. The dietary supplement should provide the daily requirement of trace elements in the human body; therefore, it should be added to the product in a normalized amount and evenly distributed in the product.Two nuclear magnetic resonance (NMR and electron paramagnetic resonance (EPR analysis were performed to determine the distribution of the additive in food products. The analysis was carried out in two stages respectively: study of molecules mobility by measuring the spin-spin relaxation time (Т2 and spin-lattice relaxation (Т1 on a pulsed NMR spectrometer; establishment of a connection between the exponent of the amplitude of the sample A0 and its mass. Based on the data obtained, as a result of the measurement, a curve is constructed for the dependence of the amplitude of the echo signal from the value (time interval between the probing pulses. The spin label used in this work is one of the first variants of a paramagnetic probe-an easily accessible transition metal ion Mn2+. According to the constructed graphs and tomograms from the
International Nuclear Information System (INIS)
Zhang Weiqian; Huang Kaiping; Cheng Guangqing
2012-01-01
In the 504 hydrotherm type mineral deposit, Mo, Hg, Ni, Re, Te, Se element (Mo, Hg are industrial mineral deposit and Ni, Re, Te, Se are scarce element) reach the industrial integrated utilization request, the scarce element widely distributed in acid orebody (upper ore zone) and alkali orebody (lower ore zone). Based on composite samples of uranium ore in the analysis, through computer processing, the linear regression and R-factor analysis, Reveals the relationship between uranium and other elements. They haven't correlation among the U, Hg, Mo. The relation- ship among the Ni, Re, Te, Se is germane. Using this correlation, deep in the deposit and surrounding exploration provides the basis for deep. (authors)
Directory of Open Access Journals (Sweden)
V. G. Margaryan
2017-12-01
Full Text Available The regularities of the space-temporal distribution of the radiation balance of the underlying surface for the conditions of the mountainous territory of the Republic of Armenia were discussed and analyzed.
DEFF Research Database (Denmark)
Peyghami, Saeed; Mokhtari, Hossein; Loh, Poh Chiang
2018-01-01
In an ac microgrid, a common frequency exists for coordinating active power sharing among droop-controlled sources. A common frequency is absent in a dc microgrid, leaving only the dc source voltages for coordinating active power sharing. That causes sharing error and poorer voltage regulation in...
DEFF Research Database (Denmark)
Ebersbach, Gitte; Ringgaard, Simon; Møller-Jensen, Jakob
2006-01-01
with each other in a bacterial two-hybrid assay but do not interact with FtsZ, eight other essential cell division proteins or MreB actin. Based on these observations, we propose a simple model for how oscillating ParA filaments can mediate regular cellular distribution of plasmids. The model functions...
Directory of Open Access Journals (Sweden)
Toralf eNeuling
2012-09-01
Full Text Available Transcranial direct current stimulation (tDCS has been applied in numerous scientiﬁc studies over the past decade. However, the possibility to apply tDCS in therapy of neuropsychiatric disorders is still debated. While transcranial magnetic stimulation (TMS has been approved for treatment of major depression in the United States by the Food and Drug Administration (FDA, tDCS is not as widely accepted. One of the criticisms against tDCS is the lack of spatial speciﬁcity. Focality is limited by the electrode size (35 cm2 are commonly used and the bipolar arrangement. However, a current ﬂow through the head directly from anode to cathode is an outdated view. Finite element (FE models have recently been used to predict the exact current ﬂow during tDCS. These simulations have demonstrated that the current ﬂow depends on tissue shape and conductivity. Toface the challenge to predict the location, magnitude and direction of the current ﬂow induced by tDCS and transcranial alternating current stimulation (tACS, we used a reﬁned realistic FE modeling approach. With respect to the literature on clinical tDCS and tACS, we analyzed two common setups for the location of the stimulation electrodes which target the frontal lobe and the occipital lobe, respectively. We compared lateral and medial electrode conﬁguration with regard to theirusability. We were able to demonstrate that the lateral conﬁgurations yielded more focused stimulation areas as well as higher current intensities in the target areas. The high resolution of our simulation allows one to combine the modeled current ﬂow with the knowledge of neuronal orientation to predict the consequences of tDCS and tACS. Our results not only oﬀer a basis for a deeper understanding of the stimulation sites currently in use for clinical applications but also oﬀer a better interpretation of observed eﬀects.
Takahashi, Go; Akashi, Haruaki
AC atmospheric pressure multi-filament dielectric barrier discharge in oxygen has been simulated using two dimensional fluid model. In the discharge, three kinds of streamers have been obtained. They are primary streamers, small scale streamers and secondary streamers. The primary streamers are main streamers in the discharge and the small scale streamers are formed after the ceasing of the primary streamers. And the secondary streamers are formed on the trace of the primary streamers. In these streamers, the primary and the small scale streamers are very effective to generate O(3P) oxygen atoms which are precursor of ozone. And the ozone is generated mainly in the vicinity of the dielectrics. In high gas temperature region, ozone generation decreases in general. However, increase of the O(3P) oxygen atom density in high gas temperature region compensates decrease of ozone generation rate coefficient. As a result, amount of ozone generation has not changed. But if the effect of gas temperature was neglected, amount of ozone generation increases 10%.
Aruna, S. A.; Zhang, P.; Lin, F. Y.; Ding, S. Y.; Yao, X. X.
2000-04-01
Within the framework of the thermally activated process of the flux line or flux line bundles, and by time integration of the 1D equation of motion of the circulating current density icons/Journals/Common/vecJ" ALT="vecJ" ALIGN="TOP"/> (icons/Journals/Common/rho" ALT="rho" ALIGN="TOP"/> ,t ), which is suitable for thin superconducting films (R >>d ,icons/Journals/Common/le" ALT="le" ALIGN="TOP"/> icons/Journals/Common/lambda" ALT="lambda" ALIGN="TOP"/> ), we present numerical calculations of the current profiles, magnetization hysteresis loops and ac susceptibility icons/Journals/Common/chi" ALT="chi" ALIGN="TOP"/> n = icons/Journals/Common/chi" ALT="chi" ALIGN="TOP"/> ´n +iicons/Journals/Common/chi" ALT="chi" ALIGN="TOP"/> ´´n for n = 1, 3 and 5 of a thin disc immersed in an axial time-dependent external magnetic field Ba (t ) = Bdc +Bac cos(2icons/Journals/Common/pi" ALT="pi" ALIGN="TOP"/> icons/Journals/Common/nu" ALT="nu" ALIGN="TOP"/> t ). Our calculated results are compared with those of the critical state model (CSM) and found to prove the approximate validity of the CSM below the irreversibility field. The differences between our computed results and those of the CSM are also discussed.
Energy Technology Data Exchange (ETDEWEB)
Weiss, Roland [Siemens AG, Erlangen (Germany); Boeke, Ulrich [Philips Group Innovation-Research, Eindhoven (Netherlands); Maurer, Wilhelm [Infineon Technologies AG, Neubiberg (Germany); Zeltner, Stefan [Fraunhofer-Inst. fuer Integrierte Systeme und Bauelementetechnologie (IISB), Erlangen (Germany)
2012-07-01
The joint undertaking ''Direct Current Components and Grid'' (DCC+G) takes on the strategic challenge to reduce energy consumption and thus the reduction of CO{sub 2} emission caused by commercially used buildings through research in the fields of Direct Current distribution at a voltage level of {+-} 380 V. The major energy consumers in commercially used buildings, ready for the ''net-zero-energy'' goal of the European Union, are heat pumps for heating, ventilation systems, air conditioning units, cooling units (HVAC), lighting systems and information technology. All these components and subsystems have in common, that the most efficient versions would benefit from a direct current supply. Additionally the local producers of electric energy like photovoltaic systems usually generate DC-current. A Direct Current distribution grid within buildings would avoid the repeating conversion from DC and AC an vice versa and therefore reduce conversion losses. Important components of a direct current distribution grid are central, smart, high efficient, bidirectional rectifiers replacing the large number of small, less efficient rectifiers used today. Such large central rectifiers units could additionally be used to actively improve the power quality of the smart local AC distribution grid. One major part of the described activities is to show energy savings of about 5 % of electrical energy with a 2-phase direct current distribution grid using a voltage level of {+-} 380 V. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Yuan Weijia; Campbell, A M; Hong, Z; Ainslie, M D; Coombs, T A, E-mail: wy215@cam.ac.u [Electronic, Power and Energy Conversion Group, Electrical Engineering Division, Engineering Department, University of Cambridge, Cambridge CB3 0FA (United Kingdom)
2010-08-15
A model is presented for calculating the AC losses, magnetic field/current density distribution and critical currents of a circular superconducting pancake coil. The assumption is that the magnetic flux lines will lie parallel to the wide faces of tapes in the unpenetrated area of the coil. Instead of using an infinitely long stack to approximate the circular coil, this paper gives an exact circular coil model using elliptic integrals. A new efficient numerical method is introduced to yield more accurate and fast computation. The computation results are in good agreement with the assumptions. For a small value of the coil radius, there is an asymmetry along the coil radius direction. As the coil radius increases, this asymmetry will gradually decrease, and the AC losses and penetration depth will increase, but the critical current will decrease. We find that if the internal radius is equal to the winding thickness, the infinitely long stack approximation overestimates the loss by 10% and even if the internal radius is reduced to zero, the error is still only 60%. The infinitely long stack approximation is therefore adequate for most practical purposes. In addition, the comparison result shows that the infinitely long stack approximation saves computation time significantly.
International Nuclear Information System (INIS)
Rijssel, Jos van; Kuipers, Bonny W.M.; Erné, Ben H.
2014-01-01
A numerical inversion method known from the analysis of light scattering by colloidal dispersions is now applied to magnetization curves of ferrofluids. The distribution of magnetic particle sizes or dipole moments is determined without assuming that the distribution is unimodal or of a particular shape. The inversion method enforces positive number densities via a non-negative least squares procedure. It is tested successfully on experimental and simulated data for ferrofluid samples with known multimodal size distributions. The created computer program MINORIM is made available on the web. - Highlights: • A method from light scattering is applied to analyze ferrofluid magnetization curves. • A magnetic size distribution is obtained without prior assumption of its shape. • The method is tested successfully on ferrofluids with a known size distribution. • The practical limits of the method are explored with simulated data including noise. • This method is implemented in the program MINORIM, freely available online
Energy Technology Data Exchange (ETDEWEB)
Prabakar, Kumaraguru [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Ainsworth, Nathan [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Pratt, Annabelle [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Baggu, Murali M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Hariri, Ali [Formerly NREL
2017-10-06
Power hardware-in-the-loop (PHIL) simulation, where actual hardware under text is coupled with a real-time digital model in closed loop, is a powerful tool for analyzing new methods of control for emerging distributed power systems. However, without careful design and compensation of the interface between the simulated and actual systems, PHIL simulations may exhibit instability and modeling inaccuracies. This paper addresses issues that arise in the PHIL simulation of a hardware battery inverter interfaced with a simulated distribution feeder. Both the stability and accuracy issues are modeled and characterized, and a methodology for design of PHIL interface compensation to ensure stability and accuracy is presented. The stability and accuracy of the resulting compensated PHIL simulation is then shown by experiment.
DEFF Research Database (Denmark)
Hansen, Lars Kai; Rasmussen, Carl Edward; Svarer, C.
1994-01-01
Regularization, e.g., in the form of weight decay, is important for training and optimization of neural network architectures. In this work the authors provide a tool based on asymptotic sampling theory, for iterative estimation of weight decay parameters. The basic idea is to do a gradient desce...
Study on ac losses of HTS coil carrying ac transport current
International Nuclear Information System (INIS)
Dai Taozhen; Tang Yuejin; Li Jingdong; Zhou Yusheng; Cheng Shijie; Pan Yuan
2005-01-01
Ac loss has an important influence on the thermal performances of HTS coil. It is necessary to quantify ac loss to ascertain its impact on coil stability and for sizing the coil refrigeration system. In this paper, we analyzed in detail the ac loss components, hysteresis loss, eddy loss and flux flow loss in the pancake HTS coil carrying ac transport current by finite element method. We also investigated the distribution of the ac losses in the coil to study the effects of magnetic field distribution on ac losses
de Jong, Peter W; Hemerik, Lia; Gort, Gerrit; van Alphen, Jacques J M
2011-01-01
Females of the larval parasitoid of Drosophila, Asobara citri, from sub-Saharan Africa, defend patches with hosts by fighting and chasing conspecific females upon encounter. Females of the closely related, palearctic species Asobara tabida do not defend patches and often search simultaneously in the same patch. The effect of patch defence by A. citri females on their distribution in a multi-patch environment was investigated, and their distributions were compared with those of A. tabida. For both species 20 females were released from two release-points in replicate experiments. Females of A. citri quickly reached a regular distribution across 16 patches, with a small variance/mean ratio per patch. Conversely, A. tabida females initially showed a clumped distribution, and after gradual dispersion, a more Poisson-like distribution across patches resulted (variance/mean ratio was closer to 1 and higher than for A. citri). The dispersion of A. tabida was most probably an effect of exploitation: these parasitoids increasingly made shorter visits to already exploited patches. We briefly discuss hypotheses on the adaptive significance of patch defence behaviour or its absence in the light of differences in the natural history of both parasitoid species, notably the spatial distribution of their hosts.
Ji, Mei; Li, Qiang; Ji, Hua; Lou, Hongxiang
2014-01-01
This study aims to investigate the change trend of resveratrol contents in different tissues of Vitis amurensis Rupr. during the different seasons in a year. A rapid and sensitive method using high-performance liquid chromatography coupled with diode array detection and tandem mass spectrometry was developed. Resveratrol is mainly distributed in the rhizomes and roots of grape plants. It is also found in leaves and vines, but to a lesser extent. Resveratrol contents are augmented gradually in rhizomes and roots from January to September, and then decrease until January of the following year. During grape ripening, grape skins are also an available source of resveratrol. In conclusion, V. amurensis is a rich source of resveratrol. The distribution of resveratrol in V. amurensis reported in this study can contribute to the future application of resveratrol. Copyright © 2013 Elsevier Ltd. All rights reserved.
Swanson, C.; Jandovitz, P.; Cohen, S. A.
2018-02-01
We measured Electron Energy Distribution Functions (EEDFs) from below 200 eV to over 8 keV and spanning five orders-of-magnitude in intensity, produced in a low-power, RF-heated, tandem mirror discharge in the PFRC-II apparatus. The EEDF was obtained from the x-ray energy distribution function (XEDF) using a novel Poisson-regularized spectrum inversion algorithm applied to pulse-height spectra that included both Bremsstrahlung and line emissions. The XEDF was measured using a specially calibrated Amptek Silicon Drift Detector (SDD) pulse-height system with 125 eV FWHM at 5.9 keV. The algorithm is found to out-perform current leading x-ray inversion algorithms when the error due to counting statistics is high.
An ac initiation system is described which uses three ac transmission signals interlocked for safety by frequency, phase, and power discrimination...The ac initiation system is pre-armed by the application of two ac signals have the proper phases, and activates a load when an ac power signal of the proper frequency and power level is applied. (Author)
Directory of Open Access Journals (Sweden)
Roberts Mike D
2010-11-01
Full Text Available Abstract Background This study's purpose investigated the impact of different macronutrient distributions and varying caloric intakes along with regular exercise for metabolic and physiological changes related to weight loss. Methods One hundred forty-one sedentary, obese women (38.7 ± 8.0 yrs, 163.3 ± 6.9 cm, 93.2 ± 16.5 kg, 35.0 ± 6.2 kg•m-2, 44.8 ± 4.2% fat were randomized to either no diet + no exercise control group (CON a no diet + exercise control (ND, or one of four diet + exercise groups (high-energy diet [HED], very low carbohydrate, high protein diet [VLCHP], low carbohydrate, moderate protein diet [LCMP] and high carbohydrate, low protein [HCLP] in addition to beginning a 3x•week-1 supervised resistance training program. After 0, 1, 10 and 14 weeks, all participants completed testing sessions which included anthropometric, body composition, energy expenditure, fasting blood samples, aerobic and muscular fitness assessments. Data were analyzed using repeated measures ANOVA with an alpha of 0.05 with LSD post-hoc analysis when appropriate. Results All dieting groups exhibited adequate compliance to their prescribed diet regimen as energy and macronutrient amounts and distributions were close to prescribed amounts. Those groups that followed a diet and exercise program reported significantly greater anthropometric (waist circumference and body mass and body composition via DXA (fat mass and % fat changes. Caloric restriction initially reduced energy expenditure, but successfully returned to baseline values after 10 weeks of dieting and exercising. Significant fitness improvements (aerobic capacity and maximal strength occurred in all exercising groups. No significant changes occurred in lipid panel constituents, but serum insulin and HOMA-IR values decreased in the VLCHP group. Significant reductions in serum leptin occurred in all caloric restriction + exercise groups after 14 weeks, which were unchanged in other non
Crisanto-Neto, J. C.; da Luz, M. G. E.; Raposo, E. P.; Viswanathan, G. M.
2016-09-01
In practice, the Lévy α-stable distribution is usually expressed in terms of the Fourier integral of its characteristic function. Indeed, known closed form expressions are relatively scarce given the huge parameters space: 0\\lt α ≤slant 2 ({{L\\'{e}vy}} {{index}}), -1≤slant β ≤slant 1 ({{skewness}}),σ \\gt 0 ({{scale}}), and -∞ \\lt μ \\lt ∞ ({{shift}}). Hence, systematic efforts have been made towards the development of proper methods for analytically solving the mentioned integral. As a further contribution in this direction, here we propose a new way to tackle the problem. We consider an approach in which one first solves the Fourier integral through a formal (thus not necessarily convergent) series representation. Then, one uses (if necessary) a pertinent sum-regularization procedure to the resulting divergent series, so as to obtain an exact formula for the distribution, which is amenable to direct numerical calculations. As a concrete study, we address the centered, symmetric, unshifted and unscaled distribution (β =0, μ =0, σ =1), with α ={α }M=2/M, M=1,2,3\\ldots . Conceivably, the present protocol could be applied to other sets of parameter values.
Energy Technology Data Exchange (ETDEWEB)
Hipp, Katharina, E-mail: katharina.hipp@bio.uni-stuttgart.de [University of Stuttgart, Institute of Biomaterials and biomolecular Systems, Department of Molecular Biology and Plant Virology, Pfaffenwaldring 57, 70550 Stuttgart (Germany); Rau, Peter; Schäfer, Benjamin [University of Stuttgart, Institute of Biomaterials and biomolecular Systems, Department of Molecular Biology and Plant Virology, Pfaffenwaldring 57, 70550 Stuttgart (Germany); Pfannstiel, Jens [University of Hohenheim, Mass Spectrometry Core Facility, August-von-Hartmann-Straße 3, 70599 Stuttgart (Germany); Jeske, Holger [University of Stuttgart, Institute of Biomaterials and biomolecular Systems, Department of Molecular Biology and Plant Virology, Pfaffenwaldring 57, 70550 Stuttgart (Germany)
2016-11-15
Plant infecting geminiviruses encode a small (A)C4 protein within the open reading frame of the replication-initiator protein. In African cassava mosaic virus, two in-frame start codons may be used for the translation of a longer and a shorter AC4 variant. Both were fused to green fluorescent protein or glutathione-S-transferase genes and expressed in fission yeast. The longer variant accumulated in discrete spots in the cytoplasm, whereas the shorter variant localized to the plasma membrane. A similar expression pattern was found in plants. A myristoylation motif may promote a targeting of the shorter variant to the plasma membrane. Mass spectrometry analysis of the yeast-expressed shorter variant detected the corresponding myristoylation. The biological relevance of the second start codon was confirmed using mutated infectious clones. Whereas mutating the first start codon had no effect on the infectivity in Nicotiana benthamiana plants, the second start codon proved to be essential. -- Highlights: •The ACMV AC4 may be translated from one or the other in-frame start codon. •Both AC4 variants are translated in fission yeast. •The long AC4 protein localizes to the cytoplasm, the short to the plasma membrane. •The short variant is myristoylated in yeast and may promote membrane localization. •Only the shorter AC4 variant has an impact on viral infections in plants.
International Nuclear Information System (INIS)
Hipp, Katharina; Rau, Peter; Schäfer, Benjamin; Pfannstiel, Jens; Jeske, Holger
2016-01-01
Plant infecting geminiviruses encode a small (A)C4 protein within the open reading frame of the replication-initiator protein. In African cassava mosaic virus, two in-frame start codons may be used for the translation of a longer and a shorter AC4 variant. Both were fused to green fluorescent protein or glutathione-S-transferase genes and expressed in fission yeast. The longer variant accumulated in discrete spots in the cytoplasm, whereas the shorter variant localized to the plasma membrane. A similar expression pattern was found in plants. A myristoylation motif may promote a targeting of the shorter variant to the plasma membrane. Mass spectrometry analysis of the yeast-expressed shorter variant detected the corresponding myristoylation. The biological relevance of the second start codon was confirmed using mutated infectious clones. Whereas mutating the first start codon had no effect on the infectivity in Nicotiana benthamiana plants, the second start codon proved to be essential. -- Highlights: •The ACMV AC4 may be translated from one or the other in-frame start codon. •Both AC4 variants are translated in fission yeast. •The long AC4 protein localizes to the cytoplasm, the short to the plasma membrane. •The short variant is myristoylated in yeast and may promote membrane localization. •Only the shorter AC4 variant has an impact on viral infections in plants.
General inverse problems for regular variation
DEFF Research Database (Denmark)
Damek, Ewa; Mikosch, Thomas Valentin; Rosinski, Jan
2014-01-01
Regular variation of distributional tails is known to be preserved by various linear transformations of some random structures. An inverse problem for regular variation aims at understanding whether the regular variation of a transformed random object is caused by regular variation of components ...
Directory of Open Access Journals (Sweden)
Timofei K. Zlobin
2012-01-01
Full Text Available The catastrophic Simushir earthquake occurred on 15 November 2006 in the Kuril-Okhotsk region in the Middle Kuril Islands which is a transition zone between the Eurasian continent and the Pacific Ocean. It was followed by numerous strong earthquakes. It is established that the catastrophic earthquake was prepared on a site characterized by increased relative effective pressures which is located at the border of the low-pressure area (Figure 1.Based on data from GlobalCMT (Harvard, earthquake focal mechanisms were reconstructed, and tectonic stresses, the seismotectonic setting and the earthquakes distribution pattern were studied for analysis of the field of stresses in the region before to the Simushir earthquake (Figures 2 and 3; Table 1.Five areas of various types of movement were determined. Three of them are stretched along the Kuril Islands. It is established that seismodislocations in earthquake focal areas are regularly distributed. In each of the determined areas, displacements of a specific type (shear or reverse shear are concentrated and give evidence of the alteration and change of zones characterized by horizontal stretching and compression.The presence of the horizontal stretching and compression zones can be explained by a model of subduction (Figure 4. Detailed studies of the state of stresses of the Kuril region confirm such zones (Figure 5. Recent GeodynamicsThe established specific features of tectonic stresses before the catastrophic Simushir earthquake of 15 November 2006 contribute to studies of earthquake forecasting problems. The state of stresses and the geodynamic conditions suggesting occurrence of new earthquakes can be assessed from the data on the distribution of horizontal compression, stretching and shear areas of the Earth’s crust and the upper mantle in the Kuril region.
UNFOLDED REGULAR AND SEMI-REGULAR POLYHEDRA
Directory of Open Access Journals (Sweden)
IONIŢĂ Elena
2015-06-01
Full Text Available This paper proposes a presentation unfolding regular and semi-regular polyhedra. Regular polyhedra are convex polyhedra whose faces are regular and equal polygons, with the same number of sides, and whose polyhedral angles are also regular and equal. Semi-regular polyhedra are convex polyhedra with regular polygon faces, several types and equal solid angles of the same type. A net of a polyhedron is a collection of edges in the plane which are the unfolded edges of the solid. Modeling and unfolding Platonic and Arhimediene polyhedra will be using 3dsMAX program. This paper is intended as an example of descriptive geometry applications.
Jung, D. H.; Moon, I. K.; Jeong, Y. H.
2001-01-01
A new ac calorimeter, utilizing the Peltier effect of a thermocouple junction as an ac power source, is described. This Peltier ac calorimeter allows to measure the absolute value of heat capacity of small solid samples with sub-milligrams of mass. The calorimeter can also be used as a dynamic one with a dynamic range of several decades at low frequencies.
This patent describes a low offset AC correlator avoids DC offset and low frequency noise by frequency operating the correlation signal so that low...noise, low level AC amplification can be substituted for DC amplification. Subsequently, the high level AC signal is demodulated to a DC level. (Author)
The AC photovoltaic module is here!
Strong, Steven J.; Wohlgemuth, John H.; Wills, Robert H.
1997-02-01
This paper describes the design, development, and performance results of a large-area photovoltaic module whose electrical output is ac power suitable for direct connection to the utility grid. The large-area ac PV module features a dedicated, integrally mounted, high-efficiency dc-to-ac power inverter with a nominal output of 250 watts (STC) at 120 Vac, 60 H, that is fully compatible with utility power. The module's output is connected directly to the building's conventional ac distribution system without need for any dc wiring, string combiners, dc ground-fault protection or additional power-conditioning equipment. With its advantages, the ac photovoltaic module promises to become a universal building block for use in all utility-interactive PV systems. This paper discusses AC Module design aspects and utility interface issues (including islanding).
Directory of Open Access Journals (Sweden)
Rusalin Lucian R. Păun
2008-05-01
Full Text Available This paper propose a new control technique forsingle – phase AC – AC converters used for a on-line UPSwith a good dynamic response, a reduced-partscomponents, a good output characteristic, a good powerfactorcorrection(PFC. This converter no needs anisolation transformer. A power factor correction rectifierand an inverter with the proposed control scheme has beendesigned and simulated using Caspoc2007, validating theconcept.
Operation of AC Adapters Visualized Using Light-Emitting Diodes
Regester, Jeffrey
2016-01-01
A bridge rectifier is a diamond-shaped configuration of diodes that serves to convert alternating current(AC) into direct current (DC). In our world of AC outlets and DC electronics, they are ubiquitous. Of course, most bridge rectifiers are built with regular diodes, not the light-emitting variety, because LEDs have a number of disadvantages. For…
Coordinate-invariant regularization
International Nuclear Information System (INIS)
Halpern, M.B.
1987-01-01
A general phase-space framework for coordinate-invariant regularization is given. The development is geometric, with all regularization contained in regularized DeWitt Superstructures on field deformations. Parallel development of invariant coordinate-space regularization is obtained by regularized functional integration of the momenta. As representative examples of the general formulation, the regularized general non-linear sigma model and regularized quantum gravity are discussed. copyright 1987 Academic Press, Inc
Cooperative Frequency Control for Autonomous AC Microgrids
DEFF Research Database (Denmark)
Shafiee, Qobad; Quintero, Juan Carlos Vasquez; Guerrero, Josep M.
2015-01-01
Distributed secondary control strategies have been recently studied for frequency regulation in droop-based AC Microgrids. Unlike centralized secondary control, the distributed one might fail to provide frequency synchronization and proportional active power sharing simultaneously, due to having...... not require measuring the system frequency as compared to the other presented methods. An ac Microgrid with four sources is used to verify the performance of the proposed control methodology....
Adaptive regularization of noisy linear inverse problems
DEFF Research Database (Denmark)
Hansen, Lars Kai; Madsen, Kristoffer Hougaard; Lehn-Schiøler, Tue
2006-01-01
In the Bayesian modeling framework there is a close relation between regularization and the prior distribution over parameters. For prior distributions in the exponential family, we show that the optimal hyper-parameter, i.e., the optimal strength of regularization, satisfies a simple relation: T......: The expectation of the regularization function, i.e., takes the same value in the posterior and prior distribution. We present three examples: two simulations, and application in fMRI neuroimaging....
Several fluidic tuned AC Amplifiers were designed and tested. Interstage tuning and feedback designs are considered. Good results were obtained...corresponding Q’s as high as 12. Element designs and test results of one, two, and three stage amplifiers are presented. AC Modulated Carrier Systems
International Nuclear Information System (INIS)
Law, H.
1987-01-01
An ac power supply system includes a rectifier fed by a normal ac supply, and an inverter connected to the rectifier by a dc link, the inverter being effective to invert the dc output of the receiver at a required frequency to provide an ac output. A dc backup power supply of lower voltage than the normal dc output of the rectifier is connected across the dc link such that the ac output of the rectifier is derived from the backup supply if the voltage of the output of the inverter falls below that of the backup supply. The dc backup power may be derived from a backup ac supply. Use in pumping coolant in nuclear reactor is envisaged. (author)
Dolphin, Andrew
2005-07-01
The uncertainties in the photometric zero points create a fundamental limit to the accuracy of photometry. The current state of the ACS calibration is surprisingly poor, with zero point uncertainties of 0.03 magnitudes. The reason for this is that the ACS calibrations are based primarily on semi-emprical synthetic zero points and observations of fields too crowded for accurate ground-based photometry. I propose to remedy this problem by obtaining ACS images of the omega Cen standard field with all nine broadband ACS/WFC filters. This will permit the direct determination of the ACS zero points by comparison with excellent ground-based photometry, and should reduce their uncertainties to less than 0.01 magnitudes. A second benefit is that it will facilitate the comparison of the WFPC2 and ACS photometric systems, which will be important as WFPC2 is phased out and ACS becomes HST's primary imager. Finally, three of the filters will be repeated from my Cycle 12 observations, allowing for a measurement of any change in sensitivity.
African Journals Online (AJOL)
USER
2010-08-16
Aug 16, 2010 ... biosynthesis pathway and plays an important role in insect growth and .... Construction and propagation of recombined AcMNPV. The recombined ... infected by virus increased with incubation time (Figure. 3). The growth of ...
electron- emission (multipactor) region, and (3) the low-frequency region. The breakdown mechanism in each of these regions is explained. An extensive bibliography on AC breakdown in gases is included.
is shown that the maximum ac efficiency is equal to approximately 70% of the corresponding dc value. An illustrative example, including a proposed design for a rather unconventional transformer, is appended. (Author)
Fluid queues and regular variation
Boxma, O.J.
1996-01-01
This paper considers a fluid queueing system, fed by N independent sources that alternate between silence and activity periods. We assume that the distribution of the activity periods of one or more sources is a regularly varying function of index ¿. We show that its fat tail gives rise to an even
Fluid queues and regular variation
O.J. Boxma (Onno)
1996-01-01
textabstractThis paper considers a fluid queueing system, fed by $N$ independent sources that alternate between silence and activity periods. We assume that the distribution of the activity periods of one or more sources is a regularly varying function of index $zeta$. We show that its fat tail
van Dam, Edwin R.; Koolen, Jack H.; Tanaka, Hajime
2016-01-01
This is a survey of distance-regular graphs. We present an introduction to distance-regular graphs for the reader who is unfamiliar with the subject, and then give an overview of some developments in the area of distance-regular graphs since the monograph 'BCN'[Brouwer, A.E., Cohen, A.M., Neumaier,
Nijholt, Antinus
1980-01-01
Culik II and Cogen introduced the class of LR-regular grammars, an extension of the LR(k) grammars. In this paper we consider an analogous extension of the LL(k) grammars called the LL-regular grammars. The relation of this class of grammars to other classes of grammars will be shown. Any LL-regular
Regular Expression Pocket Reference
Stubblebine, Tony
2007-01-01
This handy little book offers programmers a complete overview of the syntax and semantics of regular expressions that are at the heart of every text-processing application. Ideal as a quick reference, Regular Expression Pocket Reference covers the regular expression APIs for Perl 5.8, Ruby (including some upcoming 1.9 features), Java, PHP, .NET and C#, Python, vi, JavaScript, and the PCRE regular expression libraries. This concise and easy-to-use reference puts a very powerful tool for manipulating text and data right at your fingertips. Composed of a mixture of symbols and text, regular exp
International Nuclear Information System (INIS)
King, D.S.; Cox, A.N.; Hodson, S.W.
1975-01-01
Calculations indicate that AC Andromedae is population I rather than population II. A mass and radius for this star are calculated using a new set of opacities for the Kippenhahn Ia mixture. It is concluded that the mass is too high for an ordinary RR Lyrae star. (BJG)
Energy Technology Data Exchange (ETDEWEB)
Ciovati, G [Jefferson Lab (United States)
2014-07-01
This contribution provides a brief introduction to AC/RF superconductivity, with an emphasis on application to accelerators. The topics covered include the surface impedance of normal conductors and superconductors, the residual resistance, the field dependence of the surface resistance, and the superheating field.
Energy Technology Data Exchange (ETDEWEB)
Ciovati, Gianluigi [JLAB
2015-02-01
This contribution provides a brief introduction to AC/RF superconductivity, with an emphasis on application to accelerators. The topics covered include the surface impedance of normal conductors and superconductors, the residual resistance, the field dependence of the surface resistance, and the superheating field.
Regularization by External Variables
DEFF Research Database (Denmark)
Bossolini, Elena; Edwards, R.; Glendinning, P. A.
2016-01-01
Regularization was a big topic at the 2016 CRM Intensive Research Program on Advances in Nonsmooth Dynamics. There are many open questions concerning well known kinds of regularization (e.g., by smoothing or hysteresis). Here, we propose a framework for an alternative and important kind of regula......Regularization was a big topic at the 2016 CRM Intensive Research Program on Advances in Nonsmooth Dynamics. There are many open questions concerning well known kinds of regularization (e.g., by smoothing or hysteresis). Here, we propose a framework for an alternative and important kind...
Goyvaerts, Jan
2009-01-01
This cookbook provides more than 100 recipes to help you crunch data and manipulate text with regular expressions. Every programmer can find uses for regular expressions, but their power doesn't come worry-free. Even seasoned users often suffer from poor performance, false positives, false negatives, or perplexing bugs. Regular Expressions Cookbook offers step-by-step instructions for some of the most common tasks involving this tool, with recipes for C#, Java, JavaScript, Perl, PHP, Python, Ruby, and VB.NET. With this book, you will: Understand the basics of regular expressions through a
Gawryszewska, Iwona; Malinowska, Katarzyna; Kuch, Alicja; Chrobak-Chmiel, Dorota; Trokenheim, Lucja Laniewska-; Hryniewicz, Waleria; Sadowy, Ewa
2017-03-01
Enterococcus faecalis represents an important factor of hospital-associated infections (HAIs). The knowledge on its evolution from a commensal to an opportunistic pathogen is still limited; thus, we performed a study to characterise distribution of factors that may contribute to this adaptation. Using a collection obtained from various settings (hospitalised patients, community carriers, animals, fresh food, sewage, water), we investigated differences in antimicrobial susceptibility, distribution of antimicrobial resistance genes, virulence-associated determinants and phenotypes, and CRISPR loci in the context of the clonal relatedness of isolates. Bayesian Analysis of Population Structure revealed the presence of three major groups; two subgroups comprised almost exclusively HAI isolates, belonging to previously proposed enterococcal high-risk clonal complexes (HiRECCs) 6 and 28. Isolates of these two subgroups were significantly enriched in antimicrobial resistance genes, presumably produced a polysaccharide capsule and often carried the aggregation substance asa1; distribution of other virulence-associated genes, such as esp and cyl, formation of a biofilm and gelatinase production were more variable. Moreover, both subgroups showed a low prevalence of CRISPR-Cas 1 and 3 and presence of small CRISPR2 variants. Our study confirms the importance of HiRECCs in the population of E. faecalis and their confinement to the hospital settings. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Regularities of Multifractal Measures
Indian Academy of Sciences (India)
First, we prove the decomposition theorem for the regularities of multifractal Hausdorff measure and packing measure in R R d . This decomposition theorem enables us to split a set into regular and irregular parts, so that we can analyze each separately, and recombine them without affecting density properties. Next, we ...
Stochastic analytic regularization
International Nuclear Information System (INIS)
Alfaro, J.
1984-07-01
Stochastic regularization is reexamined, pointing out a restriction on its use due to a new type of divergence which is not present in the unregulated theory. Furthermore, we introduce a new form of stochastic regularization which permits the use of a minimal subtraction scheme to define the renormalized Green functions. (author)
International Nuclear Information System (INIS)
Pshenin, G.N.; Steklenkov, A.P.; Varushchenko, A.N.
1991-01-01
The analysis of space time distribution of ancient organogenous material is carried out through generalization of practically all available at the present time data on radiocarbon dating of Upper-Pleistocene and Holocene sediments in the Middle Asia. The investigations were performed to study the variability of humidification over the specific territory of the Middle Asia within a determined period of time. Three rather clearly limited vertical height intervals are determined by the results of the isotope dating of wood, coal, peat and mollus samples
Kuznetsov, A. N.; Fedorov, Yu A.; Yaroslavtsev, V. M.
2018-01-01
The study of pollutants vertical distribution in seabed sediments is of high interest as they conserve the information on the chronology of pollution level in the past. In the present paper, the results of layer by layer study of Cs-137, Am-241, Pb-210 specific activities as well as concentrations of petroleum components, lead and mercury in 48 sediment cores of the Sea of Azov, the Don River and the Kuban River are examined. In most sediment cores, two peaks of Cs-137 and Am-241 are detected. The upper of them was formed due to the Chernobyl accident in 1986 and the other is related to the global nuclear fallout of 1960s. The specific activity of naturally occurring atmospheric Lead-210 decreases exponentially with the sediment core depth. However, it is influenced by fluvial run-off, coastal erosion, Radium-226 and Radon-222 decay. The data on the radionuclides distribution in the seabed sediments is used to date them. According to the results of dating, most of petroleum components, lead and mercury quantities are concentrated in the upper sediment layer formed in the last 50 to 70 years i.e. in the period of the most important anthropogenic pressure.
Increased Ac excision (iae): Arabidopsis thaliana mutations affecting Ac transposition
International Nuclear Information System (INIS)
Jarvis, P.; Belzile, F.; Page, T.; Dean, C.
1997-01-01
The maize transposable element Ac is highly active in the heterologous hosts tobacco and tomato, but shows very much reduced levels of activity in Arabidopsis. A mutagenesis experiment was undertaken with the aim of identifying Arabidopsis host factors responsible for the observed low levels of Ac activity. Seed from a line carrying a single copy of the Ac element inserted into the streptomycin phosphotransferase (SPT) reporter fusion, and which displayed typically low levels of Ac activity, were mutagenized using gamma rays. Nineteen mutants displaying high levels of somatic Ac activity, as judged by their highly variegated phenotypes, were isolated after screening the M2 generation on streptomycin-containing medium. The mutations fall into two complementation groups, iae1 and iae2, are unlinked to the SPT::Ac locus and segregate in a Mendelian fashion. The iae1 mutation is recessive and the iae2 mutation is semi-dominant. The iae1 and iae2 mutants show 550- and 70-fold increases, respectively, in the average number of Ac excision sectors per cotyledon. The IAE1 locus maps to chromosome 2, whereas the SPT::Ac reporter maps to chromosome 3. A molecular study of Ac activity in the iae1 mutant confirmed the very high levels of Ac excision predicted using the phenotypic assay, but revealed only low levels of Ac re-insertion. Analyses of germinal transposition in the iae1 mutant demonstrated an average germinal excision frequency of 3% and a frequency of independent Ac re-insertions following germinal excision of 22%. The iae mutants represents a possible means of improving the efficiency of Ac/Ds transposon tagging systems in Arabidopsis, and will enable the dissection of host involvement in Ac transposition and the mechanisms employed for controlling transposable element activity
Sparse structure regularized ranking
Wang, Jim Jing-Yan; Sun, Yijun; Gao, Xin
2014-01-01
Learning ranking scores is critical for the multimedia database retrieval problem. In this paper, we propose a novel ranking score learning algorithm by exploring the sparse structure and using it to regularize ranking scores. To explore the sparse
Regular expression containment
DEFF Research Database (Denmark)
Henglein, Fritz; Nielsen, Lasse
2011-01-01
We present a new sound and complete axiomatization of regular expression containment. It consists of the conventional axiomatiza- tion of concatenation, alternation, empty set and (the singleton set containing) the empty string as an idempotent semiring, the fixed- point rule E* = 1 + E × E......* for Kleene-star, and a general coin- duction rule as the only additional rule. Our axiomatization gives rise to a natural computational inter- pretation of regular expressions as simple types that represent parse trees, and of containment proofs as coercions. This gives the axiom- atization a Curry......-Howard-style constructive interpretation: Con- tainment proofs do not only certify a language-theoretic contain- ment, but, under our computational interpretation, constructively transform a membership proof of a string in one regular expres- sion into a membership proof of the same string in another regular expression. We...
Supersymmetric dimensional regularization
International Nuclear Information System (INIS)
Siegel, W.; Townsend, P.K.; van Nieuwenhuizen, P.
1980-01-01
There is a simple modification of dimension regularization which preserves supersymmetry: dimensional reduction to real D < 4, followed by analytic continuation to complex D. In terms of component fields, this means fixing the ranges of all indices on the fields (and therefore the numbers of Fermi and Bose components). For superfields, it means continuing in the dimensionality of x-space while fixing the dimensionality of theta-space. This regularization procedure allows the simple manipulation of spinor derivatives in supergraph calculations. The resulting rules are: (1) First do all algebra exactly as in D = 4; (2) Then do the momentum integrals as in ordinary dimensional regularization. This regularization procedure needs extra rules before one can say that it is consistent. Such extra rules needed for superconformal anomalies are discussed. Problems associated with renormalizability and higher order loops are also discussed
Regularized maximum correntropy machine
Wang, Jim Jing-Yan; Wang, Yunji; Jing, Bing-Yi; Gao, Xin
2015-01-01
In this paper we investigate the usage of regularized correntropy framework for learning of classifiers from noisy labels. The class label predictors learned by minimizing transitional loss functions are sensitive to the noisy and outlying labels of training samples, because the transitional loss functions are equally applied to all the samples. To solve this problem, we propose to learn the class label predictors by maximizing the correntropy between the predicted labels and the true labels of the training samples, under the regularized Maximum Correntropy Criteria (MCC) framework. Moreover, we regularize the predictor parameter to control the complexity of the predictor. The learning problem is formulated by an objective function considering the parameter regularization and MCC simultaneously. By optimizing the objective function alternately, we develop a novel predictor learning algorithm. The experiments on two challenging pattern classification tasks show that it significantly outperforms the machines with transitional loss functions.
Regularized maximum correntropy machine
Wang, Jim Jing-Yan
2015-02-12
In this paper we investigate the usage of regularized correntropy framework for learning of classifiers from noisy labels. The class label predictors learned by minimizing transitional loss functions are sensitive to the noisy and outlying labels of training samples, because the transitional loss functions are equally applied to all the samples. To solve this problem, we propose to learn the class label predictors by maximizing the correntropy between the predicted labels and the true labels of the training samples, under the regularized Maximum Correntropy Criteria (MCC) framework. Moreover, we regularize the predictor parameter to control the complexity of the predictor. The learning problem is formulated by an objective function considering the parameter regularization and MCC simultaneously. By optimizing the objective function alternately, we develop a novel predictor learning algorithm. The experiments on two challenging pattern classification tasks show that it significantly outperforms the machines with transitional loss functions.
Accretion onto some well-known regular black holes
International Nuclear Information System (INIS)
Jawad, Abdul; Shahzad, M.U.
2016-01-01
In this work, we discuss the accretion onto static spherically symmetric regular black holes for specific choices of the equation of state parameter. The underlying regular black holes are charged regular black holes using the Fermi-Dirac distribution, logistic distribution, nonlinear electrodynamics, respectively, and Kehagias-Sftesos asymptotically flat regular black holes. We obtain the critical radius, critical speed, and squared sound speed during the accretion process near the regular black holes. We also study the behavior of radial velocity, energy density, and the rate of change of the mass for each of the regular black holes. (orig.)
Accretion onto some well-known regular black holes
Energy Technology Data Exchange (ETDEWEB)
Jawad, Abdul; Shahzad, M.U. [COMSATS Institute of Information Technology, Department of Mathematics, Lahore (Pakistan)
2016-03-15
In this work, we discuss the accretion onto static spherically symmetric regular black holes for specific choices of the equation of state parameter. The underlying regular black holes are charged regular black holes using the Fermi-Dirac distribution, logistic distribution, nonlinear electrodynamics, respectively, and Kehagias-Sftesos asymptotically flat regular black holes. We obtain the critical radius, critical speed, and squared sound speed during the accretion process near the regular black holes. We also study the behavior of radial velocity, energy density, and the rate of change of the mass for each of the regular black holes. (orig.)
Accretion onto some well-known regular black holes
Jawad, Abdul; Shahzad, M. Umair
2016-03-01
In this work, we discuss the accretion onto static spherically symmetric regular black holes for specific choices of the equation of state parameter. The underlying regular black holes are charged regular black holes using the Fermi-Dirac distribution, logistic distribution, nonlinear electrodynamics, respectively, and Kehagias-Sftesos asymptotically flat regular black holes. We obtain the critical radius, critical speed, and squared sound speed during the accretion process near the regular black holes. We also study the behavior of radial velocity, energy density, and the rate of change of the mass for each of the regular black holes.
Schmidt, F.
1980-11-01
The components of a superconducting 110 kV ac cable for power ratings or = 2000 MVA were developed. The cable design is of the semiflexible type, with a rigid cryogenic envelope containing a flexible hollow coaxial cable core. The cable core consists of spirally wound Nb-A1 composite wires electrically insulated by high pressure polyethylene tape wrappings. A 35 m long single phase test cable with full load terminals rated at 110 kV and 10 kA was constructed and successfully tested. The results obtained prove the technical feasibility and capability of this cable design.
International Nuclear Information System (INIS)
Meyerhoff, R.W.
1977-01-01
A noval ac superconducting cable is described. It consists of a composite structure having a superconducting surface along with a high thermally conductive material wherein the superconducting surface has the desired physical properties, geometrical shape and surface finish produced by the steps of depositing a superconducting layer upon a substrate having a predetermined surface finish and shape which conforms to that of the desired superconducting article, depositing a supporting layer of material on the superconducting layer and removing the substrate, the surface of the superconductor being a replica of the substrate surface
International Nuclear Information System (INIS)
Schmidt, F.
1980-01-01
The components of a superconducting 110 kV ac cable for power ratings >= 2000 MVA have been developed. The cable design especially considered was of the semiflexible type, with a rigid cryogenic envelope and flexible hollow coaxial cable cores pulled into the former. The cable core consists of spirally wound Nb-Al composite wires and a HDPE-tape wrapped electrical insulation. A 35 m long single phase test cable with full load terminations for 110 kV and 10 kA was constructed and successfully tested. The results obtained prove the technical feasibility and capability of our cable design. (orig.) [de
Distributed AC power flow method for AC and AC-DC hybrid ...
African Journals Online (AJOL)
DR OKE
presented here that solves the power flow problem node-wise, minimizing losses and .... The process is continued till the nodal mismatch values are negligibly small. .... operation and control; FACTS controllers; deregulation; generations and ...
On the regularized fermionic projector of the vacuum
Finster, Felix
2008-03-01
We construct families of fermionic projectors with spherically symmetric regularization, which satisfy the condition of a distributional MP-product. The method is to analyze regularization tails with a power law or logarithmic scaling in composite expressions in the fermionic projector. The resulting regularizations break the Lorentz symmetry and give rise to a multilayer structure of the fermionic projector near the light cone. Furthermore, we construct regularizations which go beyond the distributional MP-product in that they yield additional distributional contributions supported at the origin. The remaining freedom for the regularization parameters and the consequences for the normalization of the fermionic states are discussed.
On the regularized fermionic projector of the vacuum
International Nuclear Information System (INIS)
Finster, Felix
2008-01-01
We construct families of fermionic projectors with spherically symmetric regularization, which satisfy the condition of a distributional MP-product. The method is to analyze regularization tails with a power law or logarithmic scaling in composite expressions in the fermionic projector. The resulting regularizations break the Lorentz symmetry and give rise to a multilayer structure of the fermionic projector near the light cone. Furthermore, we construct regularizations which go beyond the distributional MP-product in that they yield additional distributional contributions supported at the origin. The remaining freedom for the regularization parameters and the consequences for the normalization of the fermionic states are discussed
Manifold Regularized Reinforcement Learning.
Li, Hongliang; Liu, Derong; Wang, Ding
2018-04-01
This paper introduces a novel manifold regularized reinforcement learning scheme for continuous Markov decision processes. Smooth feature representations for value function approximation can be automatically learned using the unsupervised manifold regularization method. The learned features are data-driven, and can be adapted to the geometry of the state space. Furthermore, the scheme provides a direct basis representation extension for novel samples during policy learning and control. The performance of the proposed scheme is evaluated on two benchmark control tasks, i.e., the inverted pendulum and the energy storage problem. Simulation results illustrate the concepts of the proposed scheme and show that it can obtain excellent performance.
ACS Postflash Characterization
Smith, Linda
2011-10-01
This program will evaluate the in-flight performance of the ACS/WFC post-flash lamp. A series of observations of Omega Cen will be taken using short and long exposures. The short exposures will be post-flashed using pre-determined exposure times to produce backgrounds from 0 to 125 e-. The data will be used to {1} make an empirical study of the effectiveness in preserving counts for faint stars on various post-flash backgrounds; {2} validate that our current mechanisms for formula-based and pixel-based corrections provide good fixes for whatever CTE remains; and {3} probe a fine enough range of backgrounds that users will be able to pick the level that optimizes their science, which will be a straightforward compromise between the noise added and the signal preserved.
Control of grid interactive AC microgrids
DEFF Research Database (Denmark)
Wang, Xiongfei; Guerrero, Josep M.; Chen, Zhe
2010-01-01
Over the last decade, distributed energy resources (DER) technology has undergone a fast development. Increased penetration of DER units and wide spread use of renewable energy sources challenge the entire architecture of traditional power system. Microgrid, characterizing higher flexibility......, microgrid controls and power management strategies are presented. Future trends of microgrid are discussed pointing out how this concept can be a key to achieve a more intelligent and flexible AC grid....
Predicting AC loss in practical superconductors
International Nuclear Information System (INIS)
Goemoery, F; Souc, J; Vojenciak, M; Seiler, E; Klincok, B; Ceballos, J M; Pardo, E; Sanchez, A; Navau, C; Farinon, S; Fabbricatore, P
2006-01-01
Recent progress in the development of methods used to predict AC loss in superconducting conductors is summarized. It is underlined that the loss is just one of the electromagnetic characteristics controlled by the time evolution of magnetic field and current distribution inside the conductor. Powerful methods for the simulation of magnetic flux penetration, like Brandt's method and the method of minimal magnetic energy variation, allow us to model the interaction of the conductor with an external magnetic field or a transport current, or with both of them. The case of a coincident action of AC field and AC transport current is of prime importance for practical applications. Numerical simulation methods allow us to expand the prediction range from simplified shapes like a (infinitely high) slab or (infinitely thin) strip to more realistic forms like strips with finite rectangular or elliptic cross-section. Another substantial feature of these methods is that the real composite structure containing an array of superconducting filaments can be taken into account. Also, the case of a ferromagnetic matrix can be considered, with the simulations showing a dramatic impact on the local field. In all these circumstances, it is possible to indicate how the AC loss can be reduced by a proper architecture of the composite. On the other hand, the multifilamentary arrangement brings about a presence of coupling currents and coupling loss. Simulation of this phenomenon requires 3D formulation with corresponding growth of the problem complexity and computation time
Superconductive AC current limiter
International Nuclear Information System (INIS)
Bekhaled, M.
1987-01-01
This patent describes an AC current limiter for a power transport line including a power supply circuit and feeding a load circuit via an overload circuit-breaker member. The limiter comprises a transformer having a primary winding connected in series between the power supply circuit and the load circuit and at least one secondary winding of superconductor material contained in a cryogenic enclosure and short-circuited on itself. The leakage reactance of the transformer as seen from the primary winding is low, and the resistance of the at least one secondary winding when in the non-superconducting state and as seen from the primary is much greater than the nominal impedance of the transformer. The improvement whereby the at least one secondary winding of the transformer comprises an active winding in association with a set of auxiliary windings. The set of auxiliary windings is constituted by an even number of series-connected auxiliary windings wound in opposite directions, with the total number of turns in one direction being equal to the total number of turns in the opposite direction, and with the thermal capacity of the secondary winding as a whole being sufficiently high to limit the expansion thereof to a value which remains small during the time it takes the circuit-breaking member to operate
Diverse Regular Employees and Non-regular Employment (Japanese)
MORISHIMA Motohiro
2011-01-01
Currently there are high expectations for the introduction of policies related to diverse regular employees. These policies are a response to the problem of disparities between regular and non-regular employees (part-time, temporary, contract and other non-regular employees) and will make it more likely that workers can balance work and their private lives while companies benefit from the advantages of regular employment. In this paper, I look at two issues that underlie this discussion. The ...
Sparse structure regularized ranking
Wang, Jim Jing-Yan
2014-04-17
Learning ranking scores is critical for the multimedia database retrieval problem. In this paper, we propose a novel ranking score learning algorithm by exploring the sparse structure and using it to regularize ranking scores. To explore the sparse structure, we assume that each multimedia object could be represented as a sparse linear combination of all other objects, and combination coefficients are regarded as a similarity measure between objects and used to regularize their ranking scores. Moreover, we propose to learn the sparse combination coefficients and the ranking scores simultaneously. A unified objective function is constructed with regard to both the combination coefficients and the ranking scores, and is optimized by an iterative algorithm. Experiments on two multimedia database retrieval data sets demonstrate the significant improvements of the propose algorithm over state-of-the-art ranking score learning algorithms.
ACS Photometric Zero Point Verification
Dolphin, Andrew
2003-07-01
The uncertainties in the photometric zero points create a fundamental limit to the accuracy of photometry. The current state of the ACS calibration is surprisingly poor, with zero point uncertainties of 0.03 magnitudes in the Johnson filters. The reason for this is that ACS observations of excellent ground-based standard fields, such as the omega Cen field used for WFPC2 calibrations, have not been obtained. Instead, the ACS photometric calibrations are based primarily on semi-emprical synthetic zero points and observations of fields too crowded for accurate ground-based photometry. I propose to remedy this problem by obtaining ACS broadband images of the omega Cen standard field with both the WFC and HRC. This will permit the direct determination of the ACS transformations, and is expected to double the accuracy to which the ACS zero points are known. A second benefit is that it will facilitate the comparison of the WFPC2 and ACS photometric systems, which will be important as WFPC2 is phased out and ACS becomes HST's primary imager.
'Regular' and 'emergency' repair
International Nuclear Information System (INIS)
Luchnik, N.V.
1975-01-01
Experiments on the combined action of radiation and a DNA inhibitor using Crepis roots and on split-dose irradiation of human lymphocytes lead to the conclusion that there are two types of repair. The 'regular' repair takes place twice in each mitotic cycle and ensures the maintenance of genetic stability. The 'emergency' repair is induced at all stages of the mitotic cycle by high levels of injury. (author)
Regularization of divergent integrals
Felder, Giovanni; Kazhdan, David
2016-01-01
We study the Hadamard finite part of divergent integrals of differential forms with singularities on submanifolds. We give formulae for the dependence of the finite part on the choice of regularization and express them in terms of a suitable local residue map. The cases where the submanifold is a complex hypersurface in a complex manifold and where it is a boundary component of a manifold with boundary, arising in string perturbation theory, are treated in more detail.
Regularizing portfolio optimization
International Nuclear Information System (INIS)
Still, Susanne; Kondor, Imre
2010-01-01
The optimization of large portfolios displays an inherent instability due to estimation error. This poses a fundamental problem, because solutions that are not stable under sample fluctuations may look optimal for a given sample, but are, in effect, very far from optimal with respect to the average risk. In this paper, we approach the problem from the point of view of statistical learning theory. The occurrence of the instability is intimately related to over-fitting, which can be avoided using known regularization methods. We show how regularized portfolio optimization with the expected shortfall as a risk measure is related to support vector regression. The budget constraint dictates a modification. We present the resulting optimization problem and discuss the solution. The L2 norm of the weight vector is used as a regularizer, which corresponds to a diversification 'pressure'. This means that diversification, besides counteracting downward fluctuations in some assets by upward fluctuations in others, is also crucial because it improves the stability of the solution. The approach we provide here allows for the simultaneous treatment of optimization and diversification in one framework that enables the investor to trade off between the two, depending on the size of the available dataset.
Regularizing portfolio optimization
Still, Susanne; Kondor, Imre
2010-07-01
The optimization of large portfolios displays an inherent instability due to estimation error. This poses a fundamental problem, because solutions that are not stable under sample fluctuations may look optimal for a given sample, but are, in effect, very far from optimal with respect to the average risk. In this paper, we approach the problem from the point of view of statistical learning theory. The occurrence of the instability is intimately related to over-fitting, which can be avoided using known regularization methods. We show how regularized portfolio optimization with the expected shortfall as a risk measure is related to support vector regression. The budget constraint dictates a modification. We present the resulting optimization problem and discuss the solution. The L2 norm of the weight vector is used as a regularizer, which corresponds to a diversification 'pressure'. This means that diversification, besides counteracting downward fluctuations in some assets by upward fluctuations in others, is also crucial because it improves the stability of the solution. The approach we provide here allows for the simultaneous treatment of optimization and diversification in one framework that enables the investor to trade off between the two, depending on the size of the available dataset.
Introduction to AC machine design
Lipo, Thomas A
2018-01-01
AC electrical machine design is a key skill set for developing competitive electric motors and generators for applications in industry, aerospace, and defense. This book presents a thorough treatment of AC machine design, starting from basic electromagnetic principles and continuing through the various design aspects of an induction machine. Introduction to AC Machine Design includes one chapter each on the design of permanent magnet machines, synchronous machines, and thermal design. It also offers a basic treatment of the use of finite elements to compute the magnetic field within a machine without interfering with the initial comprehension of the core subject matter. Based on the author's notes, as well as after years of classroom instruction, Introduction to AC Machine Design: * Brings to light more advanced principles of machine design--not just the basic principles of AC and DC machine behavior * Introduces electrical machine design to neophytes while also being a resource for experienced designers * ...
Two-Gyro Pointing Stability of HST measured with ACS
Koekemoer, Anton M.; Kozhurina-Platais, Vera; Riess, Adam; Sirianni, Marco; Biretta, John; Pavlovsky
2005-06-01
We present the results of the pointing stability tests for HST, as measured with the ACS/ HRC during the Two-Gyro test program conducted in February 2005. We measure the shifts of 185 exposures of the globular clusters NGC6341 and Omega Centauri, obtained over a total of 13 orbits, and compare the measured pointings to those that were commanded in the observing program. We find in all cases that the measured shifts and rotations have the same level of accuracy as those that were commanded in three-gyro mode. Specifically, the pointing offsets during an orbit relative to the first exposure can be characterized with distributions having a dispersion of 2.3 milliarcseconds for shifts and 0.00097 degrees for rotations, thus less than 0.1 HRC pixels, and agree extremely well with similar values measured for comparable exposures obtained in three-gyro mode. In addition, we successfully processed these two-gyro test data through the MultiDrizzle software which is used in the HST pipeline to perform automated registration, cosmic ray rejection and image combination for multiple exposure sequences, and we find excellent agreement with similar exposures obtained in three-gyro mode. In summary, we find no significant difference between the quality of HST pointing as measured from these two-gyro test data, relative to the nominal behavior of HST in regular three-gyro operations.
Regular Single Valued Neutrosophic Hypergraphs
Directory of Open Access Journals (Sweden)
Muhammad Aslam Malik
2016-12-01
Full Text Available In this paper, we define the regular and totally regular single valued neutrosophic hypergraphs, and discuss the order and size along with properties of regular and totally regular single valued neutrosophic hypergraphs. We also extend work on completeness of single valued neutrosophic hypergraphs.
The geometry of continuum regularization
International Nuclear Information System (INIS)
Halpern, M.B.
1987-03-01
This lecture is primarily an introduction to coordinate-invariant regularization, a recent advance in the continuum regularization program. In this context, the program is seen as fundamentally geometric, with all regularization contained in regularized DeWitt superstructures on field deformations
DC injection into low voltage AC networks
Energy Technology Data Exchange (ETDEWEB)
NONE
2005-07-01
This report summarises the results of a study investigating the impact of levels of injected DC current injections on a low voltage AC distribution network systems in order to recommend acceptable limits of DC from microgeneration. Relevant literature is reviewed, and the impact of DC levels in distribution transformers, transformer modelling, and instrumental transformers are discussed. The impact of DC in residual current devices (RCD) and in domestic electricity watt hour meters is examined along with DC enhanced corrosion, corrosion failure, and the measurement of DC current injection. Sources of DC injection outlined include DC from computer power supplies, network faults, geomagnetic phenomena, lighting circuits/dimmers, and embedded generators.
Development of a hardware-based AC microgrid for AC stability assessment
Swanson, Robert R.
As more power electronic-based devices enable the development of high-bandwidth AC microgrids, the topic of microgrid power distribution stability has become of increased interest. Recently, researchers have proposed a relatively straightforward method to assess the stability of AC systems based upon the time-constants of sources, the net bus capacitance, and the rate limits of sources. In this research, a focus has been to develop a hardware test system to evaluate AC system stability. As a first step, a time domain model of a two converter microgrid was established in which a three phase inverter acts as a power source and an active rectifier serves as an adjustable constant power AC load. The constant power load can be utilized to create rapid power flow transients to the generating system. As a second step, the inverter and active rectifier were designed using a Smart Power Module IGBT for switching and an embedded microcontroller as a processor for algorithm implementation. The inverter and active rectifier were designed to operate simultaneously using a synchronization signal to ensure each respective local controller operates in a common reference frame. Finally, the physical system was created and initial testing performed to validate the hardware functionality as a variable amplitude and variable frequency AC system.
Multiple graph regularized protein domain ranking
Wang, Jim Jing-Yan
2012-11-19
Background: Protein domain ranking is a fundamental task in structural biology. Most protein domain ranking methods rely on the pairwise comparison of protein domains while neglecting the global manifold structure of the protein domain database. Recently, graph regularized ranking that exploits the global structure of the graph defined by the pairwise similarities has been proposed. However, the existing graph regularized ranking methods are very sensitive to the choice of the graph model and parameters, and this remains a difficult problem for most of the protein domain ranking methods.Results: To tackle this problem, we have developed the Multiple Graph regularized Ranking algorithm, MultiG-Rank. Instead of using a single graph to regularize the ranking scores, MultiG-Rank approximates the intrinsic manifold of protein domain distribution by combining multiple initial graphs for the regularization. Graph weights are learned with ranking scores jointly and automatically, by alternately minimizing an objective function in an iterative algorithm. Experimental results on a subset of the ASTRAL SCOP protein domain database demonstrate that MultiG-Rank achieves a better ranking performance than single graph regularized ranking methods and pairwise similarity based ranking methods.Conclusion: The problem of graph model and parameter selection in graph regularized protein domain ranking can be solved effectively by combining multiple graphs. This aspect of generalization introduces a new frontier in applying multiple graphs to solving protein domain ranking applications. 2012 Wang et al; licensee BioMed Central Ltd.
Multiple graph regularized protein domain ranking
Wang, Jim Jing-Yan; Bensmail, Halima; Gao, Xin
2012-01-01
Background: Protein domain ranking is a fundamental task in structural biology. Most protein domain ranking methods rely on the pairwise comparison of protein domains while neglecting the global manifold structure of the protein domain database. Recently, graph regularized ranking that exploits the global structure of the graph defined by the pairwise similarities has been proposed. However, the existing graph regularized ranking methods are very sensitive to the choice of the graph model and parameters, and this remains a difficult problem for most of the protein domain ranking methods.Results: To tackle this problem, we have developed the Multiple Graph regularized Ranking algorithm, MultiG-Rank. Instead of using a single graph to regularize the ranking scores, MultiG-Rank approximates the intrinsic manifold of protein domain distribution by combining multiple initial graphs for the regularization. Graph weights are learned with ranking scores jointly and automatically, by alternately minimizing an objective function in an iterative algorithm. Experimental results on a subset of the ASTRAL SCOP protein domain database demonstrate that MultiG-Rank achieves a better ranking performance than single graph regularized ranking methods and pairwise similarity based ranking methods.Conclusion: The problem of graph model and parameter selection in graph regularized protein domain ranking can be solved effectively by combining multiple graphs. This aspect of generalization introduces a new frontier in applying multiple graphs to solving protein domain ranking applications. 2012 Wang et al; licensee BioMed Central Ltd.
Multiple graph regularized protein domain ranking.
Wang, Jim Jing-Yan; Bensmail, Halima; Gao, Xin
2012-11-19
Protein domain ranking is a fundamental task in structural biology. Most protein domain ranking methods rely on the pairwise comparison of protein domains while neglecting the global manifold structure of the protein domain database. Recently, graph regularized ranking that exploits the global structure of the graph defined by the pairwise similarities has been proposed. However, the existing graph regularized ranking methods are very sensitive to the choice of the graph model and parameters, and this remains a difficult problem for most of the protein domain ranking methods. To tackle this problem, we have developed the Multiple Graph regularized Ranking algorithm, MultiG-Rank. Instead of using a single graph to regularize the ranking scores, MultiG-Rank approximates the intrinsic manifold of protein domain distribution by combining multiple initial graphs for the regularization. Graph weights are learned with ranking scores jointly and automatically, by alternately minimizing an objective function in an iterative algorithm. Experimental results on a subset of the ASTRAL SCOP protein domain database demonstrate that MultiG-Rank achieves a better ranking performance than single graph regularized ranking methods and pairwise similarity based ranking methods. The problem of graph model and parameter selection in graph regularized protein domain ranking can be solved effectively by combining multiple graphs. This aspect of generalization introduces a new frontier in applying multiple graphs to solving protein domain ranking applications.
Multiple graph regularized protein domain ranking
Directory of Open Access Journals (Sweden)
Wang Jim
2012-11-01
Full Text Available Abstract Background Protein domain ranking is a fundamental task in structural biology. Most protein domain ranking methods rely on the pairwise comparison of protein domains while neglecting the global manifold structure of the protein domain database. Recently, graph regularized ranking that exploits the global structure of the graph defined by the pairwise similarities has been proposed. However, the existing graph regularized ranking methods are very sensitive to the choice of the graph model and parameters, and this remains a difficult problem for most of the protein domain ranking methods. Results To tackle this problem, we have developed the Multiple Graph regularized Ranking algorithm, MultiG-Rank. Instead of using a single graph to regularize the ranking scores, MultiG-Rank approximates the intrinsic manifold of protein domain distribution by combining multiple initial graphs for the regularization. Graph weights are learned with ranking scores jointly and automatically, by alternately minimizing an objective function in an iterative algorithm. Experimental results on a subset of the ASTRAL SCOP protein domain database demonstrate that MultiG-Rank achieves a better ranking performance than single graph regularized ranking methods and pairwise similarity based ranking methods. Conclusion The problem of graph model and parameter selection in graph regularized protein domain ranking can be solved effectively by combining multiple graphs. This aspect of generalization introduces a new frontier in applying multiple graphs to solving protein domain ranking applications.
Directory of Open Access Journals (Sweden)
Tobío, J. M.
1970-07-01
Full Text Available This is a very specific subject in the field of architectural acoustics, namely, insulation'. Emphasis is placed on the theoretical foundations of this phenomenon, and the most simple formula are developed to calculate easily the transmission losses of a material or the constructional insulating arrangements. The practical aspect of insulation can be considered by means of several graphs and charts, without the use of mathematics, and utilising common materials, that will not substantially increase the cost of the project. Finally this papers offers a critical discussion of building codes, and their reference to the acoustical insulation of dwellings, and data is included on the new regulations of the Madrid Municipality.Se trata un tema muy concreto de la Acústica Arquitectónica, el aislamiento, haciendo hincapié en los fundamentos teóricos del fenómeno y estableciendo las fórmulas más sencillas que permiten calcular fácilmente las pérdidas de transmisión de un material o disposición constructiva aislante. Varias gráficas y abacos permiten abordar, sin ningún tratamiento matemático, el problema práctico del aislamiento, aprovechando los materiales comunes y sin ocasionar gastos que graven sustancialmente el importe del proyecto. Por último, se hace un estudio crítico de las normas y su incidencia en los problemas del aislamiento de viviendas, incluyendo datos referentes a la nueva Ordenanza del Ayuntamiento de Madrid.
Annotation of Regular Polysemy
DEFF Research Database (Denmark)
Martinez Alonso, Hector
Regular polysemy has received a lot of attention from the theory of lexical semantics and from computational linguistics. However, there is no consensus on how to represent the sense of underspecified examples at the token level, namely when annotating or disambiguating senses of metonymic words...... and metonymic. We have conducted an analysis in English, Danish and Spanish. Later on, we have tried to replicate the human judgments by means of unsupervised and semi-supervised sense prediction. The automatic sense-prediction systems have been unable to find empiric evidence for the underspecified sense, even...
Regularity of Minimal Surfaces
Dierkes, Ulrich; Tromba, Anthony J; Kuster, Albrecht
2010-01-01
"Regularity of Minimal Surfaces" begins with a survey of minimal surfaces with free boundaries. Following this, the basic results concerning the boundary behaviour of minimal surfaces and H-surfaces with fixed or free boundaries are studied. In particular, the asymptotic expansions at interior and boundary branch points are derived, leading to general Gauss-Bonnet formulas. Furthermore, gradient estimates and asymptotic expansions for minimal surfaces with only piecewise smooth boundaries are obtained. One of the main features of free boundary value problems for minimal surfaces is t
Regularities of radiation heredity
International Nuclear Information System (INIS)
Skakov, M.K.; Melikhov, V.D.
2001-01-01
One analyzed regularities of radiation heredity in metals and alloys. One made conclusion about thermodynamically irreversible changes in structure of materials under irradiation. One offers possible ways of heredity transmittance of radiation effects at high-temperature transformations in the materials. Phenomenon of radiation heredity may be turned to practical use to control structure of liquid metal and, respectively, structure of ingot via preliminary radiation treatment of charge. Concentration microheterogeneities in material defect structure induced by preliminary irradiation represent the genetic factor of radiation heredity [ru
Annotation of regular polysemy and underspecification
DEFF Research Database (Denmark)
Martínez Alonso, Héctor; Pedersen, Bolette Sandford; Bel, Núria
2013-01-01
We present the result of an annotation task on regular polysemy for a series of seman- tic classes or dot types in English, Dan- ish and Spanish. This article describes the annotation process, the results in terms of inter-encoder agreement, and the sense distributions obtained with two methods...
Accreting fluids onto regular black holes via Hamiltonian approach
Energy Technology Data Exchange (ETDEWEB)
Jawad, Abdul [COMSATS Institute of Information Technology, Department of Mathematics, Lahore (Pakistan); Shahzad, M.U. [COMSATS Institute of Information Technology, Department of Mathematics, Lahore (Pakistan); University of Central Punjab, CAMS, UCP Business School, Lahore (Pakistan)
2017-08-15
We investigate the accretion of test fluids onto regular black holes such as Kehagias-Sfetsos black holes and regular black holes with Dagum distribution function. We analyze the accretion process when different test fluids are falling onto these regular black holes. The accreting fluid is being classified through the equation of state according to the features of regular black holes. The behavior of fluid flow and the existence of sonic points is being checked for these regular black holes. It is noted that the three-velocity depends on critical points and the equation of state parameter on phase space. (orig.)
Improved Design Methods for Robust Single- and Three-Phase ac-dc-ac Power Converters
DEFF Research Database (Denmark)
Qin, Zian
. The approaches for improving their performance, in terms of the voltage stress, efficiency, power density, cost, loss distribution, and temperature, will be studied. The structure of the thesis is as follows, Chapter 1 presents the introduction and motivation of the whole project as well as the background...... becomes a emerging challenge. Accordingly, installation of sustainable power generators like wind turbines and solar panels has experienced a large increase during the last decades. Meanwhile, power electronics converters, as interfaces in electrical system, are delivering approximately 80 % electricity...... back-to-back, and meanwhile improve the harmonics, control flexibility, and thermal distribution between the switches. Afterwards, active power decoupling methods for single-phase inverters or rectifiers that are similar to the single-phase ac-dc-ac converter, are studied in Chapter 4...
Effective field theory dimensional regularization
International Nuclear Information System (INIS)
Lehmann, Dirk; Prezeau, Gary
2002-01-01
A Lorentz-covariant regularization scheme for effective field theories with an arbitrary number of propagating heavy and light particles is given. This regularization scheme leaves the low-energy analytic structure of Greens functions intact and preserves all the symmetries of the underlying Lagrangian. The power divergences of regularized loop integrals are controlled by the low-energy kinematic variables. Simple diagrammatic rules are derived for the regularization of arbitrary one-loop graphs and the generalization to higher loops is discussed
Effective field theory dimensional regularization
Lehmann, Dirk; Prézeau, Gary
2002-01-01
A Lorentz-covariant regularization scheme for effective field theories with an arbitrary number of propagating heavy and light particles is given. This regularization scheme leaves the low-energy analytic structure of Greens functions intact and preserves all the symmetries of the underlying Lagrangian. The power divergences of regularized loop integrals are controlled by the low-energy kinematic variables. Simple diagrammatic rules are derived for the regularization of arbitrary one-loop graphs and the generalization to higher loops is discussed.
2010-12-07
... FARM CREDIT SYSTEM INSURANCE CORPORATION Regular Meeting AGENCY: Farm Credit System Insurance Corporation Board. ACTION: Regular meeting. SUMMARY: Notice is hereby given of the regular meeting of the Farm Credit System Insurance Corporation Board (Board). Date and Time: The meeting of the Board will be held...
Directory of Open Access Journals (Sweden)
Vinod Kumar Singh
2016-09-01
Full Text Available Genome-wide experimental studies in Saccharomyces cerevisiae reveal that autonomous replicating sequence (ARS requires an essential consensus sequence (ACS for replication activity. Computational studies identified thousands of ACS like patterns in the genome. However, only a few hundreds of these sites act as replicating sites and the rest are considered as dormant or evolving sites. In a bid to understand the sequence makeup of replication sites, a content and context-based analysis was performed on a set of replicating ACS sequences that binds to origin-recognition complex (ORC denoted as ORC-ACS and non-replicating ACS sequences (nrACS, that are not bound by ORC. In this study, DNA properties such as base composition, correlation, sequence dependent thermodynamic and DNA structural profiles, and their positions have been considered for characterizing ORC-ACS and nrACS. Analysis reveals that ORC-ACS depict marked differences in nucleotide composition and context features in its vicinity compared to nrACS. Interestingly, an A-rich motif was also discovered in ORC-ACS sequences within its nucleosome-free region. Profound changes in the conformational features, such as DNA helical twist, inclination angle and stacking energy between ORC-ACS and nrACS were observed. Distribution of ACS motifs in the non-coding segments points to the locations of ORC-ACS which are found far away from the adjacent gene start position compared to nrACS thereby enabling an accessible environment for ORC-proteins. Our attempt is novel in considering the contextual view of ACS and its flanking region along with nucleosome positioning in the S. cerevisiae genome and may be useful for any computational prediction scheme.
Protection of AC and DC Microgrids
DEFF Research Database (Denmark)
Beheshtaein, Siavash; Savaghebi, Mehdi; Quintero, Juan Carlos Vasquez
2015-01-01
and DC microgrids, and then investigates the existing and promising solutions for the corresponding challenges. To the authors’ knowledge, three parts of smart grids are required to be developed to facilitate implementation of protection scheme in microgrids. The main requirements and open issues......In future, distributed energy resources (RESs) will be utilized at consumption points. As a consequence, power flow and fault current would be bidirectional and topologydependent; and hence the conventional protection strategies would be inefficient. This paper categorizes the main challenges in AC...
Autonomous Operation of Hybrid Microgrid With AC and DC Subgrids
DEFF Research Database (Denmark)
Chiang Loh, Poh; Li, Ding; Kang Chai, Yi
2013-01-01
sources distributed throughout the two types of subgrids, which is certainly tougher than previous efforts developed for only ac or dc microgrid. This wider scope of control has not yet been investigated, and would certainly rely on the coordinated operation of dc sources, ac sources, and interlinking...... converters. Suitable control and normalization schemes are now developed for controlling them with the overall hybrid microgrid performance already verified in simulation and experiment.......This paper investigates on power-sharing issues of an autonomous hybrid microgrid. Unlike existing microgrids which are purely ac, the hybrid microgrid studied here comprises dc and ac subgrids interconnected by power electronic interfaces. The main challenge here is to manage power flows among all...
Extreme values, regular variation and point processes
Resnick, Sidney I
1987-01-01
Extremes Values, Regular Variation and Point Processes is a readable and efficient account of the fundamental mathematical and stochastic process techniques needed to study the behavior of extreme values of phenomena based on independent and identically distributed random variables and vectors It presents a coherent treatment of the distributional and sample path fundamental properties of extremes and records It emphasizes the core primacy of three topics necessary for understanding extremes the analytical theory of regularly varying functions; the probabilistic theory of point processes and random measures; and the link to asymptotic distribution approximations provided by the theory of weak convergence of probability measures in metric spaces The book is self-contained and requires an introductory measure-theoretic course in probability as a prerequisite Almost all sections have an extensive list of exercises which extend developments in the text, offer alternate approaches, test mastery and provide for enj...
Selection of regularization parameter for l1-regularized damage detection
Hou, Rongrong; Xia, Yong; Bao, Yuequan; Zhou, Xiaoqing
2018-06-01
The l1 regularization technique has been developed for structural health monitoring and damage detection through employing the sparsity condition of structural damage. The regularization parameter, which controls the trade-off between data fidelity and solution size of the regularization problem, exerts a crucial effect on the solution. However, the l1 regularization problem has no closed-form solution, and the regularization parameter is usually selected by experience. This study proposes two strategies of selecting the regularization parameter for the l1-regularized damage detection problem. The first method utilizes the residual and solution norms of the optimization problem and ensures that they are both small. The other method is based on the discrepancy principle, which requires that the variance of the discrepancy between the calculated and measured responses is close to the variance of the measurement noise. The two methods are applied to a cantilever beam and a three-story frame. A range of the regularization parameter, rather than one single value, can be determined. When the regularization parameter in this range is selected, the damage can be accurately identified even for multiple damage scenarios. This range also indicates the sensitivity degree of the damage identification problem to the regularization parameter.
Ensemble manifold regularization.
Geng, Bo; Tao, Dacheng; Xu, Chao; Yang, Linjun; Hua, Xian-Sheng
2012-06-01
We propose an automatic approximation of the intrinsic manifold for general semi-supervised learning (SSL) problems. Unfortunately, it is not trivial to define an optimization function to obtain optimal hyperparameters. Usually, cross validation is applied, but it does not necessarily scale up. Other problems derive from the suboptimality incurred by discrete grid search and the overfitting. Therefore, we develop an ensemble manifold regularization (EMR) framework to approximate the intrinsic manifold by combining several initial guesses. Algorithmically, we designed EMR carefully so it 1) learns both the composite manifold and the semi-supervised learner jointly, 2) is fully automatic for learning the intrinsic manifold hyperparameters implicitly, 3) is conditionally optimal for intrinsic manifold approximation under a mild and reasonable assumption, and 4) is scalable for a large number of candidate manifold hyperparameters, from both time and space perspectives. Furthermore, we prove the convergence property of EMR to the deterministic matrix at rate root-n. Extensive experiments over both synthetic and real data sets demonstrate the effectiveness of the proposed framework.
dc Arc Fault Effect on Hybrid ac/dc Microgrid
Fatima, Zahra
The advent of distributed energy resources (DER) and reliability and stability problems of the conventional grid system has given rise to the wide spread deployment of microgrids. Microgrids provide many advantages by incorporating renewable energy sources and increasing the reliability of the grid by isolating from the main grid in case of an outage. AC microgrids have been installed all over the world, but dc microgrids have been gaining interest due to the advantages they provide over ac microgrids. However the entire power network backbone is still ac and dc microgrids require expensive converters to connect to the ac power network. As a result hybrid ac/dc microgrids are gaining more attention as it combines the advantages of both ac and dc microgrids such as direct integration of ac and dc systems with minimum number of conversions which increases the efficiency by reducing energy losses. Although dc electric systems offer many advantages such as no synchronization and no reactive power, successful implementation of dc systems requires appropriate protection strategies. One unique protection challenge brought by the dc systems is dc arc faults. A dc arc fault is generated when there is a gap in the conductor due to insulation degradation and current is used to bridge the gap, resulting in an arc with very high temperature. Such a fault if it goes undetected and is not extinguished can cause damage to the entire system and cause fires. The purpose of the research is to study the effect of the dc arc fault at different locations in the hybrid ac/dc microgrid and provide insight on the reliability of the grid components when it is impacted by arc faults at various locations in the grid. The impact of dc arc fault at different locations on the performance of the PV array, wind generation, and constant power loads (CPL) interfaced with dc/dc converters is studied. MATLAB/Simulink is used to model the hybrid ac/dc microgrid and arc fault.
Hopping models and ac universality
DEFF Research Database (Denmark)
Dyre, Jeppe; Schrøder, Thomas
2002-01-01
Some general relations for hopping models are established. We proceed to discuss the universality of the ac conductivity which arises in the extreme disorder limit of the random barrier model. It is shown that the relevant dimension entering into the diffusion cluster approximation (DCA) is the h......Some general relations for hopping models are established. We proceed to discuss the universality of the ac conductivity which arises in the extreme disorder limit of the random barrier model. It is shown that the relevant dimension entering into the diffusion cluster approximation (DCA......) is the harmonic (fracton) dimension of the diffusion cluster. The temperature scaling of the dimensionless frequency entering into the DCA is discussed. Finally, some open problems regarding ac universality are listed....
Autographa californica multiple nucleopolyhedrovirus ac53 plays a role in nucleocapsid assembly
International Nuclear Information System (INIS)
Liu Chao; Li Zhaofei; Wu Wenbi; Li Lingling; Yuan Meijin; Pan Lijing; Yang Kai; Pang Yi
2008-01-01
Autographa californica multiple nucleopolyhedrovirus (AcMNPV) orf53 (ac53) is a highly conserved gene existing in all sequenced Lepidoptera and Hymenoptera baculoviruses, but its function remains unknown. To investigate its role in the baculovirus life cycle, an ac53 deletion virus (vAc ac53KO-PH-GFP ) was generated through homologous recombination in Escherichia coli. Fluorescence and light microscopy and titration analysis revealed that vAc ac53KO-PH-GFP could not produce infectious budded virus in infected Sf9 cells. Real-time PCR demonstrated that the ac53 deletion did not affect the levels of viral DNA replication. Electron microscopy showed that many lucent tubular shells devoid of the nucleoprotein core are present in the virogenic stroma and ring zone, indicating that the ac53 knockout affected nucleocapsid assembly. With a recombinant virus expressing an Ac53-GFP fusion protein, we observed that Ac53 was distributed within the cytoplasm and nucleus at 24 h post-infection, but afterwards accumulated predominantly near the nucleus-cytoplasm boundary. These data demonstrate that ac53 is involved in nucleocapsid assembly and is an essential gene for virus production
Effective one-dimensionality of universal ac hopping conduction in the extreme disorder limit
DEFF Research Database (Denmark)
Dyre, Jeppe; Schrøder, Thomas
1996-01-01
A phenomenological picture of ac hopping in the symmetric hopping model (regular lattice, equal site energies, random energy barriers) is proposed according to which conduction in the extreme disorder limit is dominated by essentially one-dimensional "percolation paths." Modeling a percolation path...... as strictly one dimensional with a sharp jump rate cutoff leads to an expression for the universal ac conductivity that fits computer simulations in two and three dimensions better than the effective medium approximation....
International Nuclear Information System (INIS)
Boutami, R.; Borge, M.J.G.; Mach, H.; Kurcewicz, W.; Fraile, L.M.; Gulda, K.; Aas, A.J.; Garcia-Raffi, L.M.; Lovhoiden, G.; Martinez, T.; Rubio, B.; Tain, J.L.; Tengblad, O.
2008-01-01
The low-energy structure of 231 Ac has been investigated by means of γ ray spectroscopy following the β - decay of 231 Ra. Multipolarities of 28 transitions have been established by measuring conversion electrons with a MINI-ORANGE electron spectrometer. The decay scheme of 231 Ra → 231 Ac has been constructed for the first time. The Advanced Time Delayed βγγ(t) method has been used to measure the half-lives of five levels. The moderately fast B(E1) transition rates derived suggest that the octupole effects, albeit weak, are still present in this exotic nucleus
The Hubble Legacy Archive ACS grism data
Kümmel, M.; Rosati, P.; Fosbury, R.; Haase, J.; Hook, R. N.; Kuntschner, H.; Lombardi, M.; Micol, A.; Nilsson, K. K.; Stoehr, F.; Walsh, J. R.
2011-06-01
A public release of slitless spectra, obtained with ACS/WFC and the G800L grism, is presented. Spectra were automatically extracted in a uniform way from 153 archival fields (or "associations") distributed across the two Galactic caps, covering all observations to 2008. The ACS G800L grism provides a wavelength range of 0.55-1.00 μm, with a dispersion of 40 Å/pixel and a resolution of ~80 Å for point-like sources. The ACS G800L images and matched direct images were reduced with an automatic pipeline that handles all steps from archive retrieval, alignment and astrometric calibration, direct image combination, catalogue generation, spectral extraction and collection of metadata. The large number of extracted spectra (73,581) demanded automatic methods for quality control and an automated classification algorithm was trained on the visual inspection of several thousand spectra. The final sample of quality controlled spectra includes 47 919 datasets (65% of the total number of extracted spectra) for 32 149 unique objects, with a median iAB-band magnitude of 23.7, reaching 26.5 AB for the faintest objects. Each released dataset contains science-ready 1D and 2D spectra, as well as multi-band image cutouts of corresponding sources and a useful preview page summarising the direct and slitless data, astrometric and photometric parameters. This release is part of the continuing effort to enhance the content of the Hubble Legacy Archive (HLA) with highly processed data products which significantly facilitate the scientific exploitation of the Hubble data. In order to characterize the slitless spectra, emission-line flux and equivalent width sensitivity of the ACS data were compared with public ground-based spectra in the GOODS-South field. An example list of emission line galaxies with two or more identified lines is also included, covering the redshift range 0.2 - 4.6. Almost all redshift determinations outside of the GOODS fields are new. The scope of science projects
Adaptive Regularization of Neural Classifiers
DEFF Research Database (Denmark)
Andersen, Lars Nonboe; Larsen, Jan; Hansen, Lars Kai
1997-01-01
We present a regularization scheme which iteratively adapts the regularization parameters by minimizing the validation error. It is suggested to use the adaptive regularization scheme in conjunction with optimal brain damage pruning to optimize the architecture and to avoid overfitting. Furthermo......, we propose an improved neural classification architecture eliminating an inherent redundancy in the widely used SoftMax classification network. Numerical results demonstrate the viability of the method...
Sobota, A.; Kanters, J.H.M.; Manders, F.; Veldhuizen, van E.M.; Haverlag, M.
2010-01-01
Our aim was to examine the starting behaviour of mid-pressure argon discharges in pin-pin (point-to-point) geometry, typically used in HID lamps. We focused our work on AC ignition of 300 and 700 mbar Ar discharges in Philips 70W standard burners. Frequency was varied between 200 kHz and 1 MHz. In
Frequency-dependent tACS modulation of BOLD signal during rhythmic visual stimulation.
Chai, Yuhui; Sheng, Jingwei; Bandettini, Peter A; Gao, Jia-Hong
2018-05-01
Transcranial alternating current stimulation (tACS) has emerged as a promising tool for modulating cortical oscillations. In previous electroencephalogram (EEG) studies, tACS has been found to modulate brain oscillatory activity in a frequency-specific manner. However, the spatial distribution and hemodynamic response for this modulation remains poorly understood. Functional magnetic resonance imaging (fMRI) has the advantage of measuring neuronal activity in regions not only below the tACS electrodes but also across the whole brain with high spatial resolution. Here, we measured fMRI signal while applying tACS to modulate rhythmic visual activity. During fMRI acquisition, tACS at different frequencies (4, 8, 16, and 32 Hz) was applied along with visual flicker stimulation at 8 and 16 Hz. We analyzed the blood-oxygen-level-dependent (BOLD) signal difference between tACS-ON vs tACS-OFF, and different frequency combinations (e.g., 4 Hz tACS, 8 Hz flicker vs 8 Hz tACS, 8 Hz flicker). We observed significant tACS modulation effects on BOLD responses when the tACS frequency matched the visual flicker frequency or the second harmonic frequency. The main effects were predominantly seen in regions that were activated by the visual task and targeted by the tACS current distribution. These findings bridge different scientific domains of tACS research and demonstrate that fMRI could localize the tACS effect on stimulus-induced brain rhythms, which could lead to a new approach for understanding the high-level cognitive process shaped by the ongoing oscillatory signal. © 2018 Wiley Periodicals, Inc.
Lifescience Database Archive (English)
Full Text Available in 5-4 OS=Homo sap... 33 1.1 sp|Q9DBY1|SYVN1_MOUSE E3 ubiquitin-protein ligase synoviolin OS=... 33 1.4 sp|Q...86TM6|SYVN1_HUMAN E3 ubiquitin-protein ligase synoviolin OS=... 33 1.4 sp|O55188|DMP1_MOUSE Dentin matrix ac
2010-09-02
... FARM CREDIT SYSTEM INSURANCE CORPORATION Regular Meeting AGENCY: Farm Credit System Insurance Corporation Board. SUMMARY: Notice is hereby given of the regular meeting of the Farm Credit System Insurance Corporation Board (Board). DATE AND TIME: The meeting of the Board will be held at the offices of the Farm...
Online co-regularized algorithms
Ruijter, T. de; Tsivtsivadze, E.; Heskes, T.
2012-01-01
We propose an online co-regularized learning algorithm for classification and regression tasks. We demonstrate that by sequentially co-regularizing prediction functions on unlabeled data points, our algorithm provides improved performance in comparison to supervised methods on several UCI benchmarks
Team-oriented Adaptive Droop Control for Autonomous AC Microgrids
DEFF Research Database (Denmark)
Shafiee, Qobad; Nasirian, Vahidreza; Guerrero, Josep M.
2014-01-01
This paper proposes a distributed control strategy for voltage and reactive power regulation in ac Microgrids. First, the control module introduces a voltage regulator that maintains the average voltage of the system on the rated value, keeping all bus voltages within an acceptable range. Dynamic...
Higher order total variation regularization for EIT reconstruction.
Gong, Bo; Schullcke, Benjamin; Krueger-Ziolek, Sabine; Zhang, Fan; Mueller-Lisse, Ullrich; Moeller, Knut
2018-01-08
Electrical impedance tomography (EIT) attempts to reveal the conductivity distribution of a domain based on the electrical boundary condition. This is an ill-posed inverse problem; its solution is very unstable. Total variation (TV) regularization is one of the techniques commonly employed to stabilize reconstructions. However, it is well known that TV regularization induces staircase effects, which are not realistic in clinical applications. To reduce such artifacts, modified TV regularization terms considering a higher order differential operator were developed in several previous studies. One of them is called total generalized variation (TGV) regularization. TGV regularization has been successively applied in image processing in a regular grid context. In this study, we adapted TGV regularization to the finite element model (FEM) framework for EIT reconstruction. Reconstructions using simulation and clinical data were performed. First results indicate that, in comparison to TV regularization, TGV regularization promotes more realistic images. Graphical abstract Reconstructed conductivity changes located on selected vertical lines. For each of the reconstructed images as well as the ground truth image, conductivity changes located along the selected left and right vertical lines are plotted. In these plots, the notation GT in the legend stands for ground truth, TV stands for total variation method, and TGV stands for total generalized variation method. Reconstructed conductivity distributions from the GREIT algorithm are also demonstrated.
Transition towards DC micro grids: From an AC to a hybrid AC and DC energy infrastructure
Directory of Open Access Journals (Sweden)
Evi Ploumpidou
2017-12-01
Full Text Available Our electricity is predominantly powered by alternating current (AC, ever since the War of Currents ended in the favor of Nicola Tesla at the end of the 19th century. However, lots of the appliances we use, such as electronics and lights with light-emitting diode (LED technology, work internally on direct current (DC and it is projected that the number of these appliances will increase in the near future. Another contributor to the increase in DC consumption is the ongoing electrification of mobility (Electric Vehicles (EVs. At the same time, photovoltaics (PV generate DC voltages, while the most common storage technologies also use DC. In order to integrate all these appliances and technologies to the existing AC grid, there is a need for converters which introduce power losses. By distributing DC power to DC devices instead of converting it to AC first, it is possible to avoid substantial energy losses that occur every time electricity is converted. This situation initiated the concept for the implementation of the DC-Flexhouse project. A prototype DC installation will be developed and tested in one of the buildings of the developing living lab area called the District of Tomorrow (De Wijk van Morgen which is located in Heerlen, the Netherlands. A neighborhood cooperative (Vrieheide cooperatie is also part of the consortium in order to address the aspect of social acceptance. Although DC seems to be a promising solution for a more sustainable energy system, the business case is still debatable due to both technology- and market-related challenges. The current energy infrastructure is predominantly based on AC, manufacturers produce devices based on AC standards and people are using many AC products across a long life span. This Smart Energy Buildings & Cities (SEB&C PDEng project is a contribution to the DC-Flexhouse project. The aim is to analyze the challenges in the transition to DC micro grids, assess the market potential of DC
Aperture measurements with AC dipole
Fuster Martinez, Nuria; Dilly, Joschua Werner; Nevay, Laurence James; Bruce, Roderik; Tomas Garcia, Rogelio; Redaelli, Stefano; Persson, Tobias Hakan Bjorn; CERN. Geneva. ATS Department
2018-01-01
During the MDs performed on the 15th of September and 29th of November 2017, we measured the LHC global aperture at injection with a new AC dipole method as well as using the Transverse Damper (ADT) blow-up method used during the 2017 LHC commissioning for benchmarking. In this note, the MD procedure is presented as well as the analysis of the comparison between the two methods. The possible beneﬁts of the new method are discussed.
Programmable Power Supply for AC Switching Magnet of Proton Accelerator
Jeong, Seong-Hun; Kang Heung Sik; Lee, Chi-Hwan; Lee, Hong-Gi; Park, Ki-Hyeon; Ryu, Chun-Kil; Sik Han, Hong; Suck Suh, Hyung
2005-01-01
The 100-MeV PEFP proton linac has two proton beam extraction lines for user' experiment. Each extraction line has 5 beamlines and has 5 Hz operating frequency. An AC switching magnet is used to distribute the proton beam to the 5 beamlines, An AC switching magnet is powered by PWM-controlled bipolar switching-mode converters. This converter is designed to operate at ±350A, 5 Hz programmable step output. The power supply is employed IGBT module and has controlled by a DSP (Digital Signal Process). This paper describes the design and test results of the power supply.
Continuum-regularized quantum gravity
International Nuclear Information System (INIS)
Chan Huesum; Halpern, M.B.
1987-01-01
The recent continuum regularization of d-dimensional Euclidean gravity is generalized to arbitrary power-law measure and studied in some detail as a representative example of coordinate-invariant regularization. The weak-coupling expansion of the theory illustrates a generic geometrization of regularized Schwinger-Dyson rules, generalizing previous rules in flat space and flat superspace. The rules are applied in a non-trivial explicit check of Einstein invariance at one loop: the cosmological counterterm is computed and its contribution is included in a verification that the graviton mass is zero. (orig.)
MD 349: Impedance Localization with AC-dipole
Biancacci, Nicolo; Metral, Elias; Salvant, Benoit; Papotti, Giulia; Persson, Tobias Hakan Bjorn; Tomas Garcia, Rogelio; CERN. Geneva. ATS Department
2016-01-01
The purpose of this MD is to measure the distribution of the transverse impedance of the LHC by observing the phase advance variation with intensity between the machine BPMs. Four injected bunches with different intensities are excited with an AC dipole and the turn by turn data is acquired from the BPM system. Through post-processing analysis the phase variation along the machine is depicted and, from this information, first conclusions of the impedance distribution can be drawn.
John R. Jones
1985-01-01
Quaking aspen is the most widely distributed native North American tree species (Little 1971, Sargent 1890). It grows in a great diversity of regions, environments, and communities (Harshberger 1911). Only one deciduous tree species in the world, the closely related Eurasian aspen (Populus tremula), has a wider range (Weigle and Frothingham 1911)....
AC Application of HTS Conductors in Highly Dynamic Electric Motors
International Nuclear Information System (INIS)
Oswald, B; Best, K-J; Setzer, M; Duffner, E; Soell, M; Gawalek, W; Kovalev, L K
2006-01-01
Based on recent investigations we design highly dynamic electric motors up to 400 kW and linear motors up to 120 kN linear force using HTS bulk material and HTS tapes. The introduction of HTS tapes into AC applications in electric motors needs fundamental studies on double pancake coils under transversal magnetic fields. First theoretical and experimental results on AC field distributions in double-pancake-coils and corresponding AC losses will be presented. Based on these results the simulation of the motor performance confirms extremely high power density and efficiency of both types of electric motors. Improved characteristics of rare earth permanent magnets used in our motors at low temperatures give an additional technological benefit
New regular black hole solutions
International Nuclear Information System (INIS)
Lemos, Jose P. S.; Zanchin, Vilson T.
2011-01-01
In the present work we consider general relativity coupled to Maxwell's electromagnetism and charged matter. Under the assumption of spherical symmetry, there is a particular class of solutions that correspond to regular charged black holes whose interior region is de Sitter, the exterior region is Reissner-Nordstroem and there is a charged thin-layer in-between the two. The main physical and geometrical properties of such charged regular black holes are analyzed.
Regular variation on measure chains
Czech Academy of Sciences Publication Activity Database
Řehák, Pavel; Vitovec, J.
2010-01-01
Roč. 72, č. 1 (2010), s. 439-448 ISSN 0362-546X R&D Projects: GA AV ČR KJB100190701 Institutional research plan: CEZ:AV0Z10190503 Keywords : regularly varying function * regularly varying sequence * measure chain * time scale * embedding theorem * representation theorem * second order dynamic equation * asymptotic properties Subject RIV: BA - General Mathematics Impact factor: 1.279, year: 2010 http://www.sciencedirect.com/science/article/pii/S0362546X09008475
Manifold Regularized Correlation Object Tracking
Hu, Hongwei; Ma, Bo; Shen, Jianbing; Shao, Ling
2017-01-01
In this paper, we propose a manifold regularized correlation tracking method with augmented samples. To make better use of the unlabeled data and the manifold structure of the sample space, a manifold regularization-based correlation filter is introduced, which aims to assign similar labels to neighbor samples. Meanwhile, the regression model is learned by exploiting the block-circulant structure of matrices resulting from the augmented translated samples over multiple base samples cropped fr...
On geodesics in low regularity
Sämann, Clemens; Steinbauer, Roland
2018-02-01
We consider geodesics in both Riemannian and Lorentzian manifolds with metrics of low regularity. We discuss existence of extremal curves for continuous metrics and present several old and new examples that highlight their subtle interrelation with solutions of the geodesic equations. Then we turn to the initial value problem for geodesics for locally Lipschitz continuous metrics and generalize recent results on existence, regularity and uniqueness of solutions in the sense of Filippov.
Condition Number Regularized Covariance Estimation.
Won, Joong-Ho; Lim, Johan; Kim, Seung-Jean; Rajaratnam, Bala
2013-06-01
Estimation of high-dimensional covariance matrices is known to be a difficult problem, has many applications, and is of current interest to the larger statistics community. In many applications including so-called the "large p small n " setting, the estimate of the covariance matrix is required to be not only invertible, but also well-conditioned. Although many regularization schemes attempt to do this, none of them address the ill-conditioning problem directly. In this paper, we propose a maximum likelihood approach, with the direct goal of obtaining a well-conditioned estimator. No sparsity assumption on either the covariance matrix or its inverse are are imposed, thus making our procedure more widely applicable. We demonstrate that the proposed regularization scheme is computationally efficient, yields a type of Steinian shrinkage estimator, and has a natural Bayesian interpretation. We investigate the theoretical properties of the regularized covariance estimator comprehensively, including its regularization path, and proceed to develop an approach that adaptively determines the level of regularization that is required. Finally, we demonstrate the performance of the regularized estimator in decision-theoretic comparisons and in the financial portfolio optimization setting. The proposed approach has desirable properties, and can serve as a competitive procedure, especially when the sample size is small and when a well-conditioned estimator is required.
Condition Number Regularized Covariance Estimation*
Won, Joong-Ho; Lim, Johan; Kim, Seung-Jean; Rajaratnam, Bala
2012-01-01
Estimation of high-dimensional covariance matrices is known to be a difficult problem, has many applications, and is of current interest to the larger statistics community. In many applications including so-called the “large p small n” setting, the estimate of the covariance matrix is required to be not only invertible, but also well-conditioned. Although many regularization schemes attempt to do this, none of them address the ill-conditioning problem directly. In this paper, we propose a maximum likelihood approach, with the direct goal of obtaining a well-conditioned estimator. No sparsity assumption on either the covariance matrix or its inverse are are imposed, thus making our procedure more widely applicable. We demonstrate that the proposed regularization scheme is computationally efficient, yields a type of Steinian shrinkage estimator, and has a natural Bayesian interpretation. We investigate the theoretical properties of the regularized covariance estimator comprehensively, including its regularization path, and proceed to develop an approach that adaptively determines the level of regularization that is required. Finally, we demonstrate the performance of the regularized estimator in decision-theoretic comparisons and in the financial portfolio optimization setting. The proposed approach has desirable properties, and can serve as a competitive procedure, especially when the sample size is small and when a well-conditioned estimator is required. PMID:23730197
Geometric continuum regularization of quantum field theory
International Nuclear Information System (INIS)
Halpern, M.B.
1989-01-01
An overview of the continuum regularization program is given. The program is traced from its roots in stochastic quantization, with emphasis on the examples of regularized gauge theory, the regularized general nonlinear sigma model and regularized quantum gravity. In its coordinate-invariant form, the regularization is seen as entirely geometric: only the supermetric on field deformations is regularized, and the prescription provides universal nonperturbative invariant continuum regularization across all quantum field theory. 54 refs
Performance of AC/graphite capacitors at high weight ratios of AC/graphite
Energy Technology Data Exchange (ETDEWEB)
Wang, Hongyu [IM and T Ltd., Advanced Research Center, Saga University, 1341 Yoga-machi, Saga 840-0047 (Japan); Yoshio, Masaki [Advanced Research Center, Department of Applied Chemistry, Saga University, 1341 Yoga-machi, Saga 840-0047 (Japan)
2008-03-01
The effect of negative to positive electrode materials' weight ratio on the electrochemical performance of both activated carbon (AC)/AC and AC/graphite capacitors has been investigated, especially in the terms of capacity and cycle-ability. The limited capacity charge mode has been proposed to improve the cycle performance of AC/graphite capacitors at high weight ratios of AC/graphite. (author)
A Characterization of Strong Regularity of Interval Matrices
Czech Academy of Sciences Publication Activity Database
Rohn, Jiří
2010-01-01
Roč. 20, - (2010), s. 717-722 E-ISSN 1081-3810 R&D Projects: GA ČR GA201/09/1957; GA ČR GC201/08/J020 Institutional research plan: CEZ:AV0Z10300504 Keywords : interval matrix * strong regularity * spectral radius * matrix inequality * solvability Subject RIV: BA - General Mathematics Impact factor: 0.808, year: 2010 http://www.math.technion.ac.il/iic/ ela / ela -articles/articles/vol20_pp717-722.pdf
Laplacian manifold regularization method for fluorescence molecular tomography
He, Xuelei; Wang, Xiaodong; Yi, Huangjian; Chen, Yanrong; Zhang, Xu; Yu, Jingjing; He, Xiaowei
2017-04-01
Sparse regularization methods have been widely used in fluorescence molecular tomography (FMT) for stable three-dimensional reconstruction. Generally, ℓ1-regularization-based methods allow for utilizing the sparsity nature of the target distribution. However, in addition to sparsity, the spatial structure information should be exploited as well. A joint ℓ1 and Laplacian manifold regularization model is proposed to improve the reconstruction performance, and two algorithms (with and without Barzilai-Borwein strategy) are presented to solve the regularization model. Numerical studies and in vivo experiment demonstrate that the proposed Gradient projection-resolved Laplacian manifold regularization method for the joint model performed better than the comparative algorithm for ℓ1 minimization method in both spatial aggregation and location accuracy.
DEFF Research Database (Denmark)
Klumpner, Christian; Blaabjerg, Frede
2004-01-01
independent producers/consumers to connect to multiple distribution grids in order to optimise the electricity price, as this will vary during the day from one power distribution company to another one. It will be needed to have a load that can smoothly adjust the power consumed from each power grid in order......Normally, a power converter has one supply port to connect to the power grid and one or multiple output ports to connect to AC loads that require variable voltage and variable frequency. As the trend on the energy market is towards deregulation, new converter topologies are needed to allow...... to minimize the overall energy cost or in case of special applications, to improve the system redundancy. Also, having a generator that can simultaneously feed fractions of its power into multiple grids which are not coupled (different voltage, frequency, displacement angle) and continuously adjust...
Metric regularity and subdifferential calculus
International Nuclear Information System (INIS)
Ioffe, A D
2000-01-01
The theory of metric regularity is an extension of two classical results: the Lyusternik tangent space theorem and the Graves surjection theorem. Developments in non-smooth analysis in the 1980s and 1990s paved the way for a number of far-reaching extensions of these results. It was also well understood that the phenomena behind the results are of metric origin, not connected with any linear structure. At the same time it became clear that some basic hypotheses of the subdifferential calculus are closely connected with the metric regularity of certain set-valued maps. The survey is devoted to the metric theory of metric regularity and its connection with subdifferential calculus in Banach spaces
Manifold Regularized Correlation Object Tracking.
Hu, Hongwei; Ma, Bo; Shen, Jianbing; Shao, Ling
2018-05-01
In this paper, we propose a manifold regularized correlation tracking method with augmented samples. To make better use of the unlabeled data and the manifold structure of the sample space, a manifold regularization-based correlation filter is introduced, which aims to assign similar labels to neighbor samples. Meanwhile, the regression model is learned by exploiting the block-circulant structure of matrices resulting from the augmented translated samples over multiple base samples cropped from both target and nontarget regions. Thus, the final classifier in our method is trained with positive, negative, and unlabeled base samples, which is a semisupervised learning framework. A block optimization strategy is further introduced to learn a manifold regularization-based correlation filter for efficient online tracking. Experiments on two public tracking data sets demonstrate the superior performance of our tracker compared with the state-of-the-art tracking approaches.
Dimensional regularization in configuration space
International Nuclear Information System (INIS)
Bollini, C.G.; Giambiagi, J.J.
1995-09-01
Dimensional regularization is introduced in configuration space by Fourier transforming in D-dimensions the perturbative momentum space Green functions. For this transformation, Bochner theorem is used, no extra parameters, such as those of Feynman or Bogoliubov-Shirkov are needed for convolutions. The regularized causal functions in x-space have ν-dependent moderated singularities at the origin. They can be multiplied together and Fourier transformed (Bochner) without divergence problems. The usual ultraviolet divergences appear as poles of the resultant functions of ν. Several example are discussed. (author). 9 refs
Regular algebra and finite machines
Conway, John Horton
2012-01-01
World-famous mathematician John H. Conway based this classic text on a 1966 course he taught at Cambridge University. Geared toward graduate students of mathematics, it will also prove a valuable guide to researchers and professional mathematicians.His topics cover Moore's theory of experiments, Kleene's theory of regular events and expressions, Kleene algebras, the differential calculus of events, factors and the factor matrix, and the theory of operators. Additional subjects include event classes and operator classes, some regulator algebras, context-free languages, communicative regular alg
Matrix regularization of 4-manifolds
Trzetrzelewski, M.
2012-01-01
We consider products of two 2-manifolds such as S^2 x S^2, embedded in Euclidean space and show that the corresponding 4-volume preserving diffeomorphism algebra can be approximated by a tensor product SU(N)xSU(N) i.e. functions on a manifold are approximated by the Kronecker product of two SU(N) matrices. A regularization of the 4-sphere is also performed by constructing N^2 x N^2 matrix representations of the 4-algebra (and as a byproduct of the 3-algebra which makes the regularization of S...
AC Losses and Their Thermal Effect in High Temperature Superconducting Machines
DEFF Research Database (Denmark)
Song, Xiaowei (Andy); Mijatovic, Nenad; Zou, Shengnan
2015-01-01
In transient operations or fault conditions, high temperature superconducting (HTS) machines suffer AC losses which have an influence on the thermal stability of superconducting windings. In this paper, a method to calculate AC losses and their thermal effect in HTS machines is presented....... The method consists of three sub-models that are coupled only in one direction. The magnetic field distribution is first solved in a machine model, assuming a uniform current distribution in HTS windings. The magnetic fields on the boundaries are then used as inputs for an AC loss model which has...
AC Losses and Their Thermal Effect in High-Temperature Superconducting Machines
DEFF Research Database (Denmark)
Song, Xiaowei (Andy); Mijatovic, Nenad; Zou, Shengnan
2016-01-01
In transient operations or fault conditions, hightemperature superconducting (HTS) machines suffer ac losses, which have an influence on the thermal stability of superconducting windings. In this paper, a method to calculate ac losses and their thermal effect in HTS machines is presented....... The method consists of three submodels that are coupled only in one direction. The magnetic field distribution is first solved in a machine model, assuming a uniform current distribution in HTS windings. The magnetic fields on the boundaries are then used as inputs for an ac loss model that has a homogeneous...
Likelihood ratio decisions in memory: three implied regularities.
Glanzer, Murray; Hilford, Andrew; Maloney, Laurence T
2009-06-01
We analyze four general signal detection models for recognition memory that differ in their distributional assumptions. Our analyses show that a basic assumption of signal detection theory, the likelihood ratio decision axis, implies three regularities in recognition memory: (1) the mirror effect, (2) the variance effect, and (3) the z-ROC length effect. For each model, we present the equations that produce the three regularities and show, in computed examples, how they do so. We then show that the regularities appear in data from a range of recognition studies. The analyses and data in our study support the following generalization: Individuals make efficient recognition decisions on the basis of likelihood ratios.
Distribution functions of magnetic nanoparticles determined by a numerical inversion method
International Nuclear Information System (INIS)
Bender, P; Balceris, C; Ludwig, F; Posth, O; Bogart, L K; Szczerba, W; Castro, A; Nilsson, L; Costo, R; Gavilán, H; González-Alonso, D; Pedro, I de; Barquín, L Fernández; Johansson, C
2017-01-01
In the present study, we applied a regularized inversion method to extract the particle size, magnetic moment and relaxation-time distribution of magnetic nanoparticles from small-angle x-ray scattering (SAXS), DC magnetization (DCM) and AC susceptibility (ACS) measurements. For the measurements the particles were colloidally dispersed in water. At first approximation the particles could be assumed to be spherically shaped and homogeneously magnetized single-domain particles. As model functions for the inversion, we used the particle form factor of a sphere (SAXS), the Langevin function (DCM) and the Debye model (ACS). The extracted distributions exhibited features/peaks that could be distinctly attributed to the individually dispersed and non-interacting nanoparticles. Further analysis of these peaks enabled, in combination with a prior characterization of the particle ensemble by electron microscopy and dynamic light scattering, a detailed structural and magnetic characterization of the particles. Additionally, all three extracted distributions featured peaks, which indicated deviations of the scattering (SAXS), magnetization (DCM) or relaxation (ACS) behavior from the one expected for individually dispersed, homogeneously magnetized nanoparticles. These deviations could be mainly attributed to partial agglomeration (SAXS, DCM, ACS), uncorrelated surface spins (DCM) and/or intra-well relaxation processes (ACS). The main advantage of the numerical inversion method is that no ad hoc assumptions regarding the line shape of the extracted distribution functions are required, which enabled the detection of these contributions. We highlighted this by comparing the results with the results obtained by standard model fits, where the functional form of the distributions was a priori assumed to be log-normal shaped. (paper)
Regularization of Nonmonotone Variational Inequalities
International Nuclear Information System (INIS)
Konnov, Igor V.; Ali, M.S.S.; Mazurkevich, E.O.
2006-01-01
In this paper we extend the Tikhonov-Browder regularization scheme from monotone to rather a general class of nonmonotone multivalued variational inequalities. We show that their convergence conditions hold for some classes of perfectly and nonperfectly competitive economic equilibrium problems
Lattice regularized chiral perturbation theory
International Nuclear Information System (INIS)
Borasoy, Bugra; Lewis, Randy; Ouimet, Pierre-Philippe A.
2004-01-01
Chiral perturbation theory can be defined and regularized on a spacetime lattice. A few motivations are discussed here, and an explicit lattice Lagrangian is reviewed. A particular aspect of the connection between lattice chiral perturbation theory and lattice QCD is explored through a study of the Wess-Zumino-Witten term
2011-01-20
... Meeting SUMMARY: Notice is hereby given of the regular meeting of the Farm Credit System Insurance Corporation Board (Board). Date and Time: The meeting of the Board will be held at the offices of the Farm... meeting of the Board will be open to the [[Page 3630
Forcing absoluteness and regularity properties
Ikegami, D.
2010-01-01
For a large natural class of forcing notions, we prove general equivalence theorems between forcing absoluteness statements, regularity properties, and transcendence properties over L and the core model K. We use our results to answer open questions from set theory of the reals.
Globals of Completely Regular Monoids
Institute of Scientific and Technical Information of China (English)
Wu Qian-qian; Gan Ai-ping; Du Xian-kun
2015-01-01
An element of a semigroup S is called irreducible if it cannot be expressed as a product of two elements in S both distinct from itself. In this paper we show that the class C of all completely regular monoids with irreducible identity elements satisfies the strong isomorphism property and so it is globally determined.
Empirical laws, regularity and necessity
Koningsveld, H.
1973-01-01
In this book I have tried to develop an analysis of the concept of an empirical law, an analysis that differs in many ways from the alternative analyse's found in contemporary literature dealing with the subject.
1 am referring especially to two well-known views, viz. the regularity and
Interval matrices: Regularity generates singularity
Czech Academy of Sciences Publication Activity Database
Rohn, Jiří; Shary, S.P.
2018-01-01
Roč. 540, 1 March (2018), s. 149-159 ISSN 0024-3795 Institutional support: RVO:67985807 Keywords : interval matrix * regularity * singularity * P-matrix * absolute value equation * diagonally singilarizable matrix Subject RIV: BA - General Mathematics Impact factor: 0.973, year: 2016
Regularization in Matrix Relevance Learning
Schneider, Petra; Bunte, Kerstin; Stiekema, Han; Hammer, Barbara; Villmann, Thomas; Biehl, Michael
A In this paper, we present a regularization technique to extend recently proposed matrix learning schemes in learning vector quantization (LVQ). These learning algorithms extend the concept of adaptive distance measures in LVQ to the use of relevance matrices. In general, metric learning can
Universality of ac conduction in disordered solids
DEFF Research Database (Denmark)
Dyre, Jeppe; Schrøder, Thomas
2000-01-01
The striking similarity of ac conduction in quite different disordered solids is discussed in terms of experimental results, modeling, and computer simulations. After giving an overview of experiment, a macroscopic and a microscopic model are reviewed. For both models the normalized ac conductivity...... as a function of a suitably scaled frequency becomes independent of details of the disorder in the extreme disorder limit, i.e., when the local randomly varying mobilities cover many orders of magnitude. The two universal ac conductivities are similar, but not identical; both are examples of unusual non......-power-law universalities. It is argued that ac universality reflects an underlying percolation determining dc as well as ac conductivity in the extreme disorder limit. Three analytical approximations to the universal ac conductivities are presented and compared to computer simulations. Finally, model predictions...
Convergence and fluctuations of Regularized Tyler estimators
Kammoun, Abla; Couillet, Romain; Pascal, Frederic; Alouini, Mohamed-Slim
2015-01-01
This article studies the behavior of regularized Tyler estimators (RTEs) of scatter matrices. The key advantages of these estimators are twofold. First, they guarantee by construction a good conditioning of the estimate and second, being a derivative of robust Tyler estimators, they inherit their robustness properties, notably their resilience to the presence of outliers. Nevertheless, one major problem that poses the use of RTEs in practice is represented by the question of setting the regularization parameter p. While a high value of p is likely to push all the eigenvalues away from zero, it comes at the cost of a larger bias with respect to the population covariance matrix. A deep understanding of the statistics of RTEs is essential to come up with appropriate choices for the regularization parameter. This is not an easy task and might be out of reach, unless one considers asymptotic regimes wherein the number of observations n and/or their size N increase together. First asymptotic results have recently been obtained under the assumption that N and n are large and commensurable. Interestingly, no results concerning the regime of n going to infinity with N fixed exist, even though the investigation of this assumption has usually predated the analysis of the most difficult N and n large case. This motivates our work. In particular, we prove in the present paper that the RTEs converge to a deterministic matrix when n → ∞ with N fixed, which is expressed as a function of the theoretical covariance matrix. We also derive the fluctuations of the RTEs around this deterministic matrix and establish that these fluctuations converge in distribution to a multivariate Gaussian distribution with zero mean and a covariance depending on the population covariance and the parameter.
Convergence and fluctuations of Regularized Tyler estimators
Kammoun, Abla
2015-10-26
This article studies the behavior of regularized Tyler estimators (RTEs) of scatter matrices. The key advantages of these estimators are twofold. First, they guarantee by construction a good conditioning of the estimate and second, being a derivative of robust Tyler estimators, they inherit their robustness properties, notably their resilience to the presence of outliers. Nevertheless, one major problem that poses the use of RTEs in practice is represented by the question of setting the regularization parameter p. While a high value of p is likely to push all the eigenvalues away from zero, it comes at the cost of a larger bias with respect to the population covariance matrix. A deep understanding of the statistics of RTEs is essential to come up with appropriate choices for the regularization parameter. This is not an easy task and might be out of reach, unless one considers asymptotic regimes wherein the number of observations n and/or their size N increase together. First asymptotic results have recently been obtained under the assumption that N and n are large and commensurable. Interestingly, no results concerning the regime of n going to infinity with N fixed exist, even though the investigation of this assumption has usually predated the analysis of the most difficult N and n large case. This motivates our work. In particular, we prove in the present paper that the RTEs converge to a deterministic matrix when n → ∞ with N fixed, which is expressed as a function of the theoretical covariance matrix. We also derive the fluctuations of the RTEs around this deterministic matrix and establish that these fluctuations converge in distribution to a multivariate Gaussian distribution with zero mean and a covariance depending on the population covariance and the parameter.
RHIC spin flipper AC dipole controller
Energy Technology Data Exchange (ETDEWEB)
Oddo, P.; Bai, M.; Dawson, C.; Gassner, D.; Harvey, M.; Hayes, T.; Mernick, K.; Minty, M.; Roser, T.; Severino, F.; Smith, K.
2011-03-28
The RHIC Spin Flipper's five high-Q AC dipoles which are driven by a swept frequency waveform require precise control of phase and amplitude during the sweep. This control is achieved using FPGA based feedback controllers. Multiple feedback loops are used to and dynamically tune the magnets. The current implementation and results will be presented. Work on a new spin flipper for RHIC (Relativistic Heavy Ion Collider) incorporating multiple dynamically tuned high-Q AC-dipoles has been developed for RHIC spin-physics experiments. A spin flipper is needed to cancel systematic errors by reversing the spin direction of the two colliding beams multiple times during a store. The spin flipper system consists of four DC-dipole magnets (spin rotators) and five AC-dipole magnets. Multiple AC-dipoles are needed to localize the driven coherent betatron oscillation inside the spin flipper. Operationally the AC-dipoles form two swept frequency bumps that minimize the effect of the AC-dipole dipoles outside of the spin flipper. Both AC bumps operate at the same frequency, but are phase shifted from each other. The AC-dipoles therefore require precise control over amplitude and phase making the implementation of the AC-dipole controller the central challenge.
International Nuclear Information System (INIS)
Miyagi, D.; Amadutsumi, Y.; Takahashi, N.; Tsukamoto, O.
2007-01-01
AC transport current losses of coated conductors with ferromagnetic substrates are higher than the loss calculated by the Norris equation. In order to reduce the AC transport current loss we propose in this paper a structure of the coated conductor that has wider substrate than the SC (Superconducting) layer. The current distribution and AC loss of the proposed model are analyzed by means of FEM. The AC transport current loss is reduced due to the change of current density distribution near the edge of SC layer, consequent to the high value of magnetic permeability of the ferromagnetic substrate, that is wider than the SC layer
Regular and conformal regular cores for static and rotating solutions
Energy Technology Data Exchange (ETDEWEB)
Azreg-Aïnou, Mustapha
2014-03-07
Using a new metric for generating rotating solutions, we derive in a general fashion the solution of an imperfect fluid and that of its conformal homolog. We discuss the conditions that the stress–energy tensors and invariant scalars be regular. On classical physical grounds, it is stressed that conformal fluids used as cores for static or rotating solutions are exempt from any malicious behavior in that they are finite and defined everywhere.
Regular and conformal regular cores for static and rotating solutions
International Nuclear Information System (INIS)
Azreg-Aïnou, Mustapha
2014-01-01
Using a new metric for generating rotating solutions, we derive in a general fashion the solution of an imperfect fluid and that of its conformal homolog. We discuss the conditions that the stress–energy tensors and invariant scalars be regular. On classical physical grounds, it is stressed that conformal fluids used as cores for static or rotating solutions are exempt from any malicious behavior in that they are finite and defined everywhere.
Multiview Hessian regularization for image annotation.
Liu, Weifeng; Tao, Dacheng
2013-07-01
The rapid development of computer hardware and Internet technology makes large scale data dependent models computationally tractable, and opens a bright avenue for annotating images through innovative machine learning algorithms. Semisupervised learning (SSL) therefore received intensive attention in recent years and was successfully deployed in image annotation. One representative work in SSL is Laplacian regularization (LR), which smoothes the conditional distribution for classification along the manifold encoded in the graph Laplacian, however, it is observed that LR biases the classification function toward a constant function that possibly results in poor generalization. In addition, LR is developed to handle uniformly distributed data (or single-view data), although instances or objects, such as images and videos, are usually represented by multiview features, such as color, shape, and texture. In this paper, we present multiview Hessian regularization (mHR) to address the above two problems in LR-based image annotation. In particular, mHR optimally combines multiple HR, each of which is obtained from a particular view of instances, and steers the classification function that varies linearly along the data manifold. We apply mHR to kernel least squares and support vector machines as two examples for image annotation. Extensive experiments on the PASCAL VOC'07 dataset validate the effectiveness of mHR by comparing it with baseline algorithms, including LR and HR.
Energy functions for regularization algorithms
Delingette, H.; Hebert, M.; Ikeuchi, K.
1991-01-01
Regularization techniques are widely used for inverse problem solving in computer vision such as surface reconstruction, edge detection, or optical flow estimation. Energy functions used for regularization algorithms measure how smooth a curve or surface is, and to render acceptable solutions these energies must verify certain properties such as invariance with Euclidean transformations or invariance with parameterization. The notion of smoothness energy is extended here to the notion of a differential stabilizer, and it is shown that to void the systematic underestimation of undercurvature for planar curve fitting, it is necessary that circles be the curves of maximum smoothness. A set of stabilizers is proposed that meet this condition as well as invariance with rotation and parameterization.
Physical model of dimensional regularization
Energy Technology Data Exchange (ETDEWEB)
Schonfeld, Jonathan F.
2016-12-15
We explicitly construct fractals of dimension 4-ε on which dimensional regularization approximates scalar-field-only quantum-field theory amplitudes. The construction does not require fractals to be Lorentz-invariant in any sense, and we argue that there probably is no Lorentz-invariant fractal of dimension greater than 2. We derive dimensional regularization's power-law screening first for fractals obtained by removing voids from 3-dimensional Euclidean space. The derivation applies techniques from elementary dielectric theory. Surprisingly, fractal geometry by itself does not guarantee the appropriate power-law behavior; boundary conditions at fractal voids also play an important role. We then extend the derivation to 4-dimensional Minkowski space. We comment on generalization to non-scalar fields, and speculate about implications for quantum gravity. (orig.)
Maximum mutual information regularized classification
Wang, Jim Jing-Yan
2014-09-07
In this paper, a novel pattern classification approach is proposed by regularizing the classifier learning to maximize mutual information between the classification response and the true class label. We argue that, with the learned classifier, the uncertainty of the true class label of a data sample should be reduced by knowing its classification response as much as possible. The reduced uncertainty is measured by the mutual information between the classification response and the true class label. To this end, when learning a linear classifier, we propose to maximize the mutual information between classification responses and true class labels of training samples, besides minimizing the classification error and reducing the classifier complexity. An objective function is constructed by modeling mutual information with entropy estimation, and it is optimized by a gradient descend method in an iterative algorithm. Experiments on two real world pattern classification problems show the significant improvements achieved by maximum mutual information regularization.
Maximum mutual information regularized classification
Wang, Jim Jing-Yan; Wang, Yi; Zhao, Shiguang; Gao, Xin
2014-01-01
In this paper, a novel pattern classification approach is proposed by regularizing the classifier learning to maximize mutual information between the classification response and the true class label. We argue that, with the learned classifier, the uncertainty of the true class label of a data sample should be reduced by knowing its classification response as much as possible. The reduced uncertainty is measured by the mutual information between the classification response and the true class label. To this end, when learning a linear classifier, we propose to maximize the mutual information between classification responses and true class labels of training samples, besides minimizing the classification error and reducing the classifier complexity. An objective function is constructed by modeling mutual information with entropy estimation, and it is optimized by a gradient descend method in an iterative algorithm. Experiments on two real world pattern classification problems show the significant improvements achieved by maximum mutual information regularization.
Regularized strings with extrinsic curvature
International Nuclear Information System (INIS)
Ambjoern, J.; Durhuus, B.
1987-07-01
We analyze models of discretized string theories, where the path integral over world sheet variables is regularized by summing over triangulated surfaces. The inclusion of curvature in the action is a necessity for the scaling of the string tension. We discuss the physical properties of models with extrinsic curvature terms in the action and show that the string tension vanishes at the critical point where the bare extrinsic curvature coupling tends to infinity. Similar results are derived for models with intrinsic curvature. (orig.)
Circuit complexity of regular languages
Czech Academy of Sciences Publication Activity Database
Koucký, Michal
2009-01-01
Roč. 45, č. 4 (2009), s. 865-879 ISSN 1432-4350 R&D Projects: GA ČR GP201/07/P276; GA MŠk(CZ) 1M0545 Institutional research plan: CEZ:AV0Z10190503 Keywords : regular languages * circuit complexity * upper and lower bounds Subject RIV: BA - General Mathematics Impact factor: 0.726, year: 2009
Bioinformatics and Astrophysics Cluster (BinAc)
Krüger, Jens; Lutz, Volker; Bartusch, Felix; Dilling, Werner; Gorska, Anna; Schäfer, Christoph; Walter, Thomas
2017-09-01
BinAC provides central high performance computing capacities for bioinformaticians and astrophysicists from the state of Baden-Württemberg. The bwForCluster BinAC is part of the implementation concept for scientific computing for the universities in Baden-Württemberg. Community specific support is offered through the bwHPC-C5 project.
Cosmic Shear With ACS Pure Parallels
Rhodes, Jason
2002-07-01
Small distortions in the shapes of background galaxies by foreground mass provide a powerful method of directly measuring the amount and distribution of dark matter. Several groups have recently detected this weak lensing by large-scale structure, also called cosmic shear. The high resolution and sensitivity of HST/ACS provide a unique opportunity to measure cosmic shear accurately on small scales. Using 260 parallel orbits in Sloan textiti {F775W} we will measure for the first time: beginlistosetlength sep0cm setlengthemsep0cm setlengthopsep0cm em the cosmic shear variance on scales Omega_m^0.5, with signal-to-noise {s/n} 20, and the mass density Omega_m with s/n=4. They will be done at small angular scales where non-linear effects dominate the power spectrum, providing a test of the gravitational instability paradigm for structure formation. Measurements on these scales are not possible from the ground, because of the systematic effects induced by PSF smearing from seeing. Having many independent lines of sight reduces the uncertainty due to cosmic variance, making parallel observations ideal.
Regularized Statistical Analysis of Anatomy
DEFF Research Database (Denmark)
Sjöstrand, Karl
2007-01-01
This thesis presents the application and development of regularized methods for the statistical analysis of anatomical structures. Focus is on structure-function relationships in the human brain, such as the connection between early onset of Alzheimer’s disease and shape changes of the corpus...... and mind. Statistics represents a quintessential part of such investigations as they are preluded by a clinical hypothesis that must be verified based on observed data. The massive amounts of image data produced in each examination pose an important and interesting statistical challenge...... efficient algorithms which make the analysis of large data sets feasible, and gives examples of applications....
Regularization methods in Banach spaces
Schuster, Thomas; Hofmann, Bernd; Kazimierski, Kamil S
2012-01-01
Regularization methods aimed at finding stable approximate solutions are a necessary tool to tackle inverse and ill-posed problems. Usually the mathematical model of an inverse problem consists of an operator equation of the first kind and often the associated forward operator acts between Hilbert spaces. However, for numerous problems the reasons for using a Hilbert space setting seem to be based rather on conventions than on an approprimate and realistic model choice, so often a Banach space setting would be closer to reality. Furthermore, sparsity constraints using general Lp-norms or the B
Academic Training Lecture - Regular Programme
PH Department
2011-01-01
Regular Lecture Programme 9 May 2011 ACT Lectures on Detectors - Inner Tracking Detectors by Pippa Wells (CERN) 10 May 2011 ACT Lectures on Detectors - Calorimeters (2/5) by Philippe Bloch (CERN) 11 May 2011 ACT Lectures on Detectors - Muon systems (3/5) by Kerstin Hoepfner (RWTH Aachen) 12 May 2011 ACT Lectures on Detectors - Particle Identification and Forward Detectors by Peter Krizan (University of Ljubljana and J. Stefan Institute, Ljubljana, Slovenia) 13 May 2011 ACT Lectures on Detectors - Trigger and Data Acquisition (5/5) by Dr. Brian Petersen (CERN) from 11:00 to 12:00 at CERN ( Bldg. 222-R-001 - Filtration Plant )
Supporting Regularized Logistic Regression Privately and Efficiently
Li, Wenfa; Liu, Hongzhe; Yang, Peng; Xie, Wei
2016-01-01
As one of the most popular statistical and machine learning models, logistic regression with regularization has found wide adoption in biomedicine, social sciences, information technology, and so on. These domains often involve data of human subjects that are contingent upon strict privacy regulations. Concerns over data privacy make it increasingly difficult to coordinate and conduct large-scale collaborative studies, which typically rely on cross-institution data sharing and joint analysis. Our work here focuses on safeguarding regularized logistic regression, a widely-used statistical model while at the same time has not been investigated from a data security and privacy perspective. We consider a common use scenario of multi-institution collaborative studies, such as in the form of research consortia or networks as widely seen in genetics, epidemiology, social sciences, etc. To make our privacy-enhancing solution practical, we demonstrate a non-conventional and computationally efficient method leveraging distributing computing and strong cryptography to provide comprehensive protection over individual-level and summary data. Extensive empirical evaluations on several studies validate the privacy guarantee, efficiency and scalability of our proposal. We also discuss the practical implications of our solution for large-scale studies and applications from various disciplines, including genetic and biomedical studies, smart grid, network analysis, etc. PMID:27271738
Supporting Regularized Logistic Regression Privately and Efficiently.
Li, Wenfa; Liu, Hongzhe; Yang, Peng; Xie, Wei
2016-01-01
As one of the most popular statistical and machine learning models, logistic regression with regularization has found wide adoption in biomedicine, social sciences, information technology, and so on. These domains often involve data of human subjects that are contingent upon strict privacy regulations. Concerns over data privacy make it increasingly difficult to coordinate and conduct large-scale collaborative studies, which typically rely on cross-institution data sharing and joint analysis. Our work here focuses on safeguarding regularized logistic regression, a widely-used statistical model while at the same time has not been investigated from a data security and privacy perspective. We consider a common use scenario of multi-institution collaborative studies, such as in the form of research consortia or networks as widely seen in genetics, epidemiology, social sciences, etc. To make our privacy-enhancing solution practical, we demonstrate a non-conventional and computationally efficient method leveraging distributing computing and strong cryptography to provide comprehensive protection over individual-level and summary data. Extensive empirical evaluations on several studies validate the privacy guarantee, efficiency and scalability of our proposal. We also discuss the practical implications of our solution for large-scale studies and applications from various disciplines, including genetic and biomedical studies, smart grid, network analysis, etc.
Supporting Regularized Logistic Regression Privately and Efficiently.
Directory of Open Access Journals (Sweden)
Wenfa Li
Full Text Available As one of the most popular statistical and machine learning models, logistic regression with regularization has found wide adoption in biomedicine, social sciences, information technology, and so on. These domains often involve data of human subjects that are contingent upon strict privacy regulations. Concerns over data privacy make it increasingly difficult to coordinate and conduct large-scale collaborative studies, which typically rely on cross-institution data sharing and joint analysis. Our work here focuses on safeguarding regularized logistic regression, a widely-used statistical model while at the same time has not been investigated from a data security and privacy perspective. We consider a common use scenario of multi-institution collaborative studies, such as in the form of research consortia or networks as widely seen in genetics, epidemiology, social sciences, etc. To make our privacy-enhancing solution practical, we demonstrate a non-conventional and computationally efficient method leveraging distributing computing and strong cryptography to provide comprehensive protection over individual-level and summary data. Extensive empirical evaluations on several studies validate the privacy guarantee, efficiency and scalability of our proposal. We also discuss the practical implications of our solution for large-scale studies and applications from various disciplines, including genetic and biomedical studies, smart grid, network analysis, etc.
Security analysis of interconnected AC/DC systems
DEFF Research Database (Denmark)
Eriksson, Robert
2015-01-01
This paper analyses N-1 security in an interconnected ac/dc transmission system using power transfer distribution factors (PTDFs). In the case of a dc converter outage the power needs to be redistributed among the remaining converter to maintain power balance and operation of the dc grid...... any line or transformer limits. Simulations were performed in a model of the Nordic power system where a dc grid is placed on top. The simulation supports the method as a tool to consider transfer limits in the grid to avoid violate the same and increase the security after a converter outage........ The redistribution of power has a sudden effect on the power-flow in the interconnected ac system. This may cause overloading of lines and transformers resulting in disconnection of equipment, and as a consequence cascading failure. The PTDF is used as a method to analyze and avoid violating limits by in the dc...
Structural characterization of the packings of granular regular polygons.
Wang, Chuncheng; Dong, Kejun; Yu, Aibing
2015-12-01
By using a recently developed method for discrete modeling of nonspherical particles, we simulate the random packings of granular regular polygons with three to 11 edges under gravity. The effects of shape and friction on the packing structures are investigated by various structural parameters, including packing fraction, the radial distribution function, coordination number, Voronoi tessellation, and bond-orientational order. We find that packing fraction is generally higher for geometrically nonfrustrated regular polygons, and can be increased by the increase of edge number and decrease of friction. The changes of packing fraction are linked with those of the microstructures, such as the variations of the translational and orientational orders and local configurations. In particular, the free areas of Voronoi tessellations (which are related to local packing fractions) can be described by log-normal distributions for all polygons. The quantitative analyses establish a clearer picture for the packings of regular polygons.
RES: Regularized Stochastic BFGS Algorithm
Mokhtari, Aryan; Ribeiro, Alejandro
2014-12-01
RES, a regularized stochastic version of the Broyden-Fletcher-Goldfarb-Shanno (BFGS) quasi-Newton method is proposed to solve convex optimization problems with stochastic objectives. The use of stochastic gradient descent algorithms is widespread, but the number of iterations required to approximate optimal arguments can be prohibitive in high dimensional problems. Application of second order methods, on the other hand, is impracticable because computation of objective function Hessian inverses incurs excessive computational cost. BFGS modifies gradient descent by introducing a Hessian approximation matrix computed from finite gradient differences. RES utilizes stochastic gradients in lieu of deterministic gradients for both, the determination of descent directions and the approximation of the objective function's curvature. Since stochastic gradients can be computed at manageable computational cost RES is realizable and retains the convergence rate advantages of its deterministic counterparts. Convergence results show that lower and upper bounds on the Hessian egeinvalues of the sample functions are sufficient to guarantee convergence to optimal arguments. Numerical experiments showcase reductions in convergence time relative to stochastic gradient descent algorithms and non-regularized stochastic versions of BFGS. An application of RES to the implementation of support vector machines is developed.
Regularized Label Relaxation Linear Regression.
Fang, Xiaozhao; Xu, Yong; Li, Xuelong; Lai, Zhihui; Wong, Wai Keung; Fang, Bingwu
2018-04-01
Linear regression (LR) and some of its variants have been widely used for classification problems. Most of these methods assume that during the learning phase, the training samples can be exactly transformed into a strict binary label matrix, which has too little freedom to fit the labels adequately. To address this problem, in this paper, we propose a novel regularized label relaxation LR method, which has the following notable characteristics. First, the proposed method relaxes the strict binary label matrix into a slack variable matrix by introducing a nonnegative label relaxation matrix into LR, which provides more freedom to fit the labels and simultaneously enlarges the margins between different classes as much as possible. Second, the proposed method constructs the class compactness graph based on manifold learning and uses it as the regularization item to avoid the problem of overfitting. The class compactness graph is used to ensure that the samples sharing the same labels can be kept close after they are transformed. Two different algorithms, which are, respectively, based on -norm and -norm loss functions are devised. These two algorithms have compact closed-form solutions in each iteration so that they are easily implemented. Extensive experiments show that these two algorithms outperform the state-of-the-art algorithms in terms of the classification accuracy and running time.
Regularities of radiorace formation in yeasts
International Nuclear Information System (INIS)
Korogodin, V.I.; Bliznik, K.M.; Kapul'tsevich, Yu.G.; Petin, V.G.; Akademiya Meditsinskikh Nauk SSSR, Obninsk. Nauchno-Issledovatel'skij Inst. Meditsinskoj Radiologii)
1977-01-01
Two strains of diploid yeast, namely, Saccharomyces ellipsoides, Megri 139-B, isolated under natural conditions, and Saccharomyces cerevisiae 5a x 3Bα, heterozygous by genes ade 1 and ade 2, were exposed to γ-quanta of Co 60 . The content of cells-saltants forming colonies with changed morphology, that of the nonviable cells, cells that are respiration mutants, and cells-recombinants by gene ade 1 and ade 2, has been determined. A certain regularity has been revealed in the distribution among the colonies of cells of the four types mentioned above: the higher the content of cells of some one of the types, the higher that of the cells having other hereditary changes
Wave dynamics of regular and chaotic rays
International Nuclear Information System (INIS)
McDonald, S.W.
1983-09-01
In order to investigate general relationships between waves and rays in chaotic systems, I study the eigenfunctions and spectrum of a simple model, the two-dimensional Helmholtz equation in a stadium boundary, for which the rays are ergodic. Statistical measurements are performed so that the apparent randomness of the stadium modes can be quantitatively contrasted with the familiar regularities observed for the modes in a circular boundary (with integrable rays). The local spatial autocorrelation of the eigenfunctions is constructed in order to indirectly test theoretical predictions for the nature of the Wigner distribution corresponding to chaotic waves. A portion of the large-eigenvalue spectrum is computed and reported in an appendix; the probability distribution of successive level spacings is analyzed and compared with theoretical predictions. The two principal conclusions are: 1) waves associated with chaotic rays may exhibit randomly situated localized regions of high intensity; 2) the Wigner function for these waves may depart significantly from being uniformly distributed over the surface of constant frequency in the ray phase space
78 FR 49318 - Availability of Draft Advisory Circular (AC) 90-106A and AC 20-167A
2013-08-13
...] Availability of Draft Advisory Circular (AC) 90-106A and AC 20- 167A AGENCY: Federal Aviation Administration... of draft Advisory Circular (AC) 90-106A, Enhanced Flight Vision Systems and draft AC 20- 167A... Federal holidays. FOR FURTHER INFORMATION CONTACT: For technical questions concerning draft AC 90-106A...
The regularized monotonicity method: detecting irregular indefinite inclusions
DEFF Research Database (Denmark)
Garde, Henrik; Staboulis, Stratos
2018-01-01
inclusions, where the conductivity distribution has both more and less conductive parts relative to the background conductivity; one such method is the monotonicity method of Harrach, Seo, and Ullrich. We formulate the method for irregular indefinite inclusions, meaning that we make no regularity assumptions...
On the number of spanning trees in random regular graphs
DEFF Research Database (Denmark)
Greenhill, Catherine; Kwan, Matthew; Wind, David Kofoed
2014-01-01
Let d >= 3 be a fixed integer. We give an asympotic formula for the expected number of spanning trees in a uniformly random d-regular graph with n vertices. (The asymptotics are as n -> infinity, restricted to even n if d is odd.) We also obtain the asymptotic distribution of the number of spanning...
Seligmann, Hervé
2016-07-01
Swinger DNAs are sequences whose homology with known sequences is detected only by assuming systematic exchanges between nucleotides. Nine symmetric (XY, i.e. AC) and fourteen asymmetric (X->Y->Z, i.e. A->C->G) exchanges exist. All swinger DNA previously detected in GenBank follow the AT+CG exchange, while mitochondrial swinger RNAs distribute among different swinger types. Here different alignment criteria detect 87 additional swinger mitochondrial DNAs (86 from insects), including the first swinger gene embedded within a complete genome, corresponding to the mitochondrial 16S rDNA of the stonefly Kamimuria wangi. Other Kamimuria mt genome regions are "regular", stressing unanswered questions on (a) swinger polymerization regulation; (b) swinger 16S rDNA functions; and (c) specificity to rDNA, in particular 16S rDNA. Sharp switches between regular and swinger replication, together with previous observations on swinger transcription, suggest that swinger replication might be due to a switch in polymerization mode of regular polymerases and the possibility of swinger-encoded information, predicted in primordial genes such as rDNA.
Nonlinear AC susceptibility, surface and bulk shielding
van der Beek, C. J.; Indenbom, M. V.; D'Anna, G.; Benoit, W.
1996-02-01
We calculate the nonlinear AC response of a thin superconducting strip in perpendicular field, shielded by an edge current due to the geometrical barrier. A comparison with the results for infinite samples in parallel field, screened by a surface barrier, and with those for screening by a bulk current in the critical state, shows that the AC response due to a barrier has general features that are independent of geometry, and that are significantly different from those for screening by a bulk current in the critical state. By consequence, the nonlinear (global) AC susceptibility can be used to determine the origin of magnetic irreversibility. A comparison with experiments on a Bi 2Sr 2CaCu 2O 8+δ crystal shows that in this material, the low-frequency AC screening at high temperature is mainly due to the screening by an edge current, and that this is the unique source of the nonlinear magnetic response at temperatures above 40 K.
Logistics Reduction: Advanced Clothing System (ACS)
National Aeronautics and Space Administration — The goal of the Advanced Exploration System (AES) Logistics Reduction (LR) project's Advanced Clothing System (ACS) is to use advanced commercial off-the-shelf...
Early function of the Abutilon mosaic virus AC2 gene as a replication brake.
Krenz, Björn; Deuschle, Kathrin; Deigner, Tobias; Unseld, Sigrid; Kepp, Gabi; Wege, Christina; Kleinow, Tatjana; Jeske, Holger
2015-04-01
The C2/AC2 genes of monopartite/bipartite geminiviruses of the genera Begomovirus and Curtovirus encode important pathogenicity factors with multiple functions described so far. A novel function of Abutilon mosaic virus (AbMV) AC2 as a replication brake is described, utilizing transgenic plants with dimeric inserts of DNA B or with a reporter construct to express green fluorescent protein (GFP). Their replicational release upon AbMV superinfection or the individual and combined expression of epitope-tagged AbMV AC1, AC2, and AC3 was studied. In addition, the effects were compared in the presence and in the absence of an unrelated tombusvirus suppressor of silencing (P19). The results show that AC2 suppresses replication reproducibly in all assays and that AC3 counteracts this effect. Examination of the topoisomer distribution of supercoiled DNA, which indicates changes in the viral minichromosome structure, did not support any influence of AC2 on transcriptional gene silencing and DNA methylation. The geminiviral AC2 protein has been detected here for the first time in plants. The experiments revealed an extremely low level of AC2, which was slightly increased if constructs with an intron and a hemagglutinin (HA) tag in addition to P19 expression were used. AbMV AC2 properties are discussed with reference to those of other geminiviruses with respect to charge, modification, and size in order to delimit possible reasons for the different behaviors. The (A)C2 genes encode a key pathogenicity factor of begomoviruses and curtoviruses in the plant virus family Geminiviridae. This factor has been implicated in the resistance breaking observed in agricultural cotton production. AC2 is a multifunctional protein involved in transcriptional control, gene silencing, and regulation of basal biosynthesis. Here, a new function of Abutilon mosaic virus AC2 in replication control is added as a feature of this protein in viral multiplication, providing a novel finding on
From inactive to regular jogger
DEFF Research Database (Denmark)
Lund-Cramer, Pernille; Brinkmann Løite, Vibeke; Bredahl, Thomas Viskum Gjelstrup
study was conducted using individual semi-structured interviews on how a successful long-term behavior change had been achieved. Ten informants were purposely selected from participants in the DANO-RUN research project (7 men, 3 women, average age 41.5). Interviews were performed on the basis of Theory...... of Planned Behavior (TPB) and The Transtheoretical Model (TTM). Coding and analysis of interviews were performed using NVivo 10 software. Results TPB: During the behavior change process, the intention to jogging shifted from a focus on weight loss and improved fitness to both physical health, psychological......Title From inactive to regular jogger - a qualitative study of achieved behavioral change among recreational joggers Authors Pernille Lund-Cramer & Vibeke Brinkmann Løite Purpose Despite extensive knowledge of barriers to physical activity, most interventions promoting physical activity have proven...
Marketingová komunikace AC Sparta Praha
Fanta, Jan
2016-01-01
Title: Marketing communications of AC Sparta Praha Objectives: The main objective of this thesis is to analyze contemporary state of marketing communications with the audience of AC Sparta Praha, identify deficiencies and develop a proposal to improve the marketing communications with fans of this club. Methods: In this thesis have been used methods of case study, analysis of available documents and texts, structured interview with director od marketing, and director of communications and pub...
Iwakuma, M; Funaki, K
2002-01-01
The ac loss properties of two-strand parallel conductors composed of superconducting multifilamentary strands were theoretically investigated. The constituent strands generally need to be insulated and transposed for the sake of uniform current distribution and low ac loss. In case the transposition points deviate from the optimum ones, shielding current is induced according to the interlinkage magnetic flux of the twisted loop enclosed by the insulated strands and the contact resistances at the terminals. It produces an additional ac loss. Supposing a simple situation where a two-strand parallel conductor with one-point transposition is exposed to a uniform ac magnetic field, the basic equations for the magnetic field were proposed and the theoretical expressions of the additional ac losses derived. As a result, the following features were shown. The additional ac loss in the non-saturation case, where the induced shielding current is less than the critical current of a strand, is proportional to the square ...
Tessellating the Sphere with Regular Polygons
Soto-Johnson, Hortensia; Bechthold, Dawn
2004-01-01
Tessellations in the Euclidean plane and regular polygons that tessellate the sphere are reviewed. The regular polygons that can possibly tesellate the sphere are spherical triangles, squares and pentagons.
On the equivalence of different regularization methods
International Nuclear Information System (INIS)
Brzezowski, S.
1985-01-01
The R-circunflex-operation preceded by the regularization procedure is discussed. Some arguments are given, according to which the results may depend on the method of regularization, introduced in order to avoid divergences in perturbation calculations. 10 refs. (author)
The uniqueness of the regularization procedure
International Nuclear Information System (INIS)
Brzezowski, S.
1981-01-01
On the grounds of the BPHZ procedure, the criteria of correct regularization in perturbation calculations of QFT are given, together with the prescription for dividing the regularized formulas into the finite and infinite parts. (author)
DEFF Research Database (Denmark)
Guerrero, Josep M.; Vásquez, Juan V.; Teodorescu, Remus
2009-01-01
DC and AC Microgrids are key elements to integrate renewable and distributed energy resources as well as distributed energy storage systems. In the last years, efforts toward the standardization of these Microgrids have been made. In this sense, this paper present the hierarchical control derived...
Transport AC losses in YBCO coated conductors
Energy Technology Data Exchange (ETDEWEB)
Majoros, M [Ohio State University, Columbus, OH 43210 (United States); Ye, L [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Velichko, A V [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Coombs, T A [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Sumption, M D [Ohio State University, Columbus, OH 43210 (United States); Collings, E W [Ohio State University, Columbus, OH 43210 (United States)
2007-09-15
Transport AC loss measurements have been made on YBCO-coated conductors prepared on two different substrate templates-RABiTS (rolling-assisted biaxially textured substrate) and IBAD (ion-beam-assisted deposition). RABiTS samples show higher losses compared with the theoretical values obtained from the critical state model, with constant critical current density, at currents lower than the critical current. An origin of this extra AC loss was demonstrated experimentally by comparison of the AC loss of two samples with different I-V curves. Despite a difference in I-V curves and in the critical currents, their measured losses, as well as the normalized losses, were practically the same. However, the functional dependence of the losses was affected by the ferromagnetic substrate. An influence of the presence of a ferromagnetic substrate on transport AC losses in YBCO film was calculated numerically by the finite element method. The presence of a ferromagnetic substrate increases transport AC losses in YBCO films depending on its relative magnetic permeability. The two loss contributions-transport AC loss in YBCO films and ferromagnetic loss in the substrate-cannot be considered as mutually independent.
Proportional-Integral-Resonant AC Current Controller
Directory of Open Access Journals (Sweden)
STOJIC, D.
2017-02-01
Full Text Available In this paper an improved stationary-frame AC current controller based on the proportional-integral-resonant control action (PIR is proposed. Namely, the novel two-parameter PIR controller is applied in the stationary-frame AC current control, accompanied by the corresponding parameter-tuning procedure. In this way, the proportional-resonant (PR controller, common in the stationary-frame AC current control, is extended by the integral (I action in order to enable the AC current DC component tracking, and, also, to enable the DC disturbance compensation, caused by the voltage source inverter (VSI nonidealities and by nonlinear loads. The proposed controller parameter-tuning procedure is based on the three-phase back-EMF-type load, which corresponds to a wide range of AC power converter applications, such as AC motor drives, uninterruptible power supplies, and active filters. While the PIR controllers commonly have three parameters, the novel controller has two. Also, the provided parameter-tuning procedure needs only one parameter to be tuned in relation to the load and power converter model parameters, since the second controller parameter is directly derived from the required controller bandwidth value. The dynamic performance of the proposed controller is verified by means of simulation and experimental runs.
Application of Turchin's method of statistical regularization
Zelenyi, Mikhail; Poliakova, Mariia; Nozik, Alexander; Khudyakov, Alexey
2018-04-01
During analysis of experimental data, one usually needs to restore a signal after it has been convoluted with some kind of apparatus function. According to Hadamard's definition this problem is ill-posed and requires regularization to provide sensible results. In this article we describe an implementation of the Turchin's method of statistical regularization based on the Bayesian approach to the regularization strategy.
Regular extensions of some classes of grammars
Nijholt, Antinus
Culik and Cohen introduced the class of LR-regular grammars, an extension of the LR(k) grammars. In this report we consider the analogous extension of the LL(k) grammers, called the LL-regular grammars. The relations of this class of grammars to other classes of grammars are shown. Every LL-regular
The Effect of the Feedback Controller on Superconducting Tokamak AC Losses + AC-CRPP user manual
International Nuclear Information System (INIS)
Schaerz, B.; Bruzzone, P.; Favez, J.Y.; Lister, J.B.; Zapretilina, E.
2001-11-01
Superconducting coils in a Tokamak are subject to AC losses when the field transverse to the coil current varies. A simple model to evaluate the AC losses has been derived and benchmarked against a complete model used in the ITER design procedure. The influence of the feedback control strategy on the AC losses is examined using this model. An improved controller is proposed, based on this study. (author)
The ACS-NUCL Division 50th Anniversary: Introduction
Energy Technology Data Exchange (ETDEWEB)
Hobart, David E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-01-10
The ACS Division of Nuclear Chemistry and Technology was initiated in 1955 as a subdivision of the Division of Industrial and Engineering Chemistry. Probationary divisional status was lifted in 1965. The Division’s first symposium was held in Denver in 1964 and it is fitting that we kicked-off the 50th Anniversary in Denver in the spring of 2015. Listed as a small ACS Division with only about 1,000 members, NUCL’s impact over the past fifty years has been remarkable. National ACS meetings have had many symposia sponsored or cosponsored by NUCL that included Nobel Laureates, U.S. Senators, other high-ranking officials and many students as speakers. The range of subjects has been exceptional as are the various prestigious awards established by the Division. Of major impact has been the past 30 years of the NUCL Nuclear Chemistry Summer Schools to help fill the void of qualified nuclear scientists and technicians. In celebrating the 50th Anniversary we honor the past, celebrate the present and shape the future of the Division and nuclear science and technology. To celebrate this auspicious occasion a commemorative lapel pin has been designed for distribution to NUCL Division members.
AC electric field induced vortex in laminar coflow diffusion flames
Xiong, Yuan; Cha, Min; Chung, Suk-Ho
2014-01-01
Experiments were performed by applying sub-critical high-voltage alternating current (AC) to the nozzle of laminar propane coflow diffusion flames. Light scattering, laser-induced incandescence and laser-induced fluorescence techniques were used to identify the soot zone, and the structures of OH and polycyclic aromatic hydrocarbons (PAHs). Particle image velocimetry was adopted to quantify the velocity field. Under certain AC conditions of applied voltage and frequency, the distribution of PAHs and the flow field near the nozzle exit were drastically altered, leading to the formation of toroidal vortices. Increased residence time and heat recirculation inside the vortex resulted in appreciable formation of PAHs and soot near the nozzle exit. Decreased residence time along the jet axis through flow acceleration by the vortex led to a reduction in the soot volume fraction in the downstream sooting zone. Electromagnetic force generated by AC was proposed as a viable mechanism for the formation of the toroidal vortex. The onset conditions for the vortex formation supported the role of an electromagnetic force acting on charged particles in the flame zone. (C) 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
AC electric field induced vortex in laminar coflow diffusion flames
Xiong, Yuan
2014-09-22
Experiments were performed by applying sub-critical high-voltage alternating current (AC) to the nozzle of laminar propane coflow diffusion flames. Light scattering, laser-induced incandescence and laser-induced fluorescence techniques were used to identify the soot zone, and the structures of OH and polycyclic aromatic hydrocarbons (PAHs). Particle image velocimetry was adopted to quantify the velocity field. Under certain AC conditions of applied voltage and frequency, the distribution of PAHs and the flow field near the nozzle exit were drastically altered, leading to the formation of toroidal vortices. Increased residence time and heat recirculation inside the vortex resulted in appreciable formation of PAHs and soot near the nozzle exit. Decreased residence time along the jet axis through flow acceleration by the vortex led to a reduction in the soot volume fraction in the downstream sooting zone. Electromagnetic force generated by AC was proposed as a viable mechanism for the formation of the toroidal vortex. The onset conditions for the vortex formation supported the role of an electromagnetic force acting on charged particles in the flame zone. (C) 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
Tian, Zhang; Yanfeng, Gong
2017-05-01
In order to solve the contradiction between demand and distribution range of primary energy resource, Ultra High Voltage (UHV) power grids should be developed rapidly to meet development of energy bases and accessing of large-scale renewable energy. This paper reviewed the latest research processes of AC/DC transmission technologies, summarized the characteristics of AC/DC power grids, concluded that China’s power grids certainly enter a new period of large -scale hybrid UHV AC/DC power grids and characteristics of “strong DC and weak AC” becomes increasingly pro minent; possible problems in operation of AC/DC power grids was discussed, and interaction or effect between AC/DC power grids was made an intensive study of; according to above problems in operation of power grids, preliminary scheme is summarized as fo llows: strengthening backbone structures, enhancing AC/DC transmission technologies, promoting protection measures of clean energ y accessing grids, and taking actions to solve stability problems of voltage and frequency etc. It’s valuable for making hybrid UHV AC/DC power grids adapt to operating mode of large power grids, thus guaranteeing security and stability of power system.
Regularities development of entrepreneurial structures in regions
Directory of Open Access Journals (Sweden)
Julia Semenovna Pinkovetskaya
2012-12-01
Full Text Available Consider regularities and tendencies for the three types of entrepreneurial structures — small enterprises, medium enterprises and individual entrepreneurs. The aim of the research was to confirm the possibilities of describing indicators of aggregate entrepreneurial structures with the use of normal law distribution functions. Presented proposed by the author the methodological approach and results of construction of the functions of the density distribution for the main indicators for the various objects: the Russian Federation, regions, as well as aggregates ofentrepreneurial structures, specialized in certain forms ofeconomic activity. All the developed functions, as shown by the logical and statistical analysis, are of high quality and well-approximate the original data. In general, the proposed methodological approach is versatile and can be used in further studies of aggregates of entrepreneurial structures. The received results can be applied in solving a wide range of problems justify the need for personnel and financial resources at the federal, regional and municipal levels, as well as the formation of plans and forecasts of development entrepreneurship and improvement of this sector of the economy.
Current Control of Grid Converters Connected with Series AC Capacitor
DEFF Research Database (Denmark)
Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang
2015-01-01
The series ac capacitor has recently been used with the transformerless grid-connected converters in the distribution power grids. The capacitive characteristic of the resulting series LC filter restricts the use of conventional synchronous integral or stationary resonant current controllers. Thus...... this paper proposes a fourth-order resonant controller in the stationary frame, which guarantees a zero steady-state current tracking error for the grid converters with series LC filter. This method is then implemented in a three-phase experimental system for verification, where the current harmonics below...... the LC filter resonance frequency are effectively eliminated. Experimental results confirm the validity of the proposed current control scheme....
Measurement of AC electrical characteristics of SSC superconducting dipole magnets
International Nuclear Information System (INIS)
Smedley, K.M.; Shafer, R.E.
1992-01-01
Experiments were conducted to measure the AC electrical characteristics of SSC superconducting dipole magnets over the frequency range of 0.1 Hz to 10 kHz. A magnet equivalent circuit representing the magnet DC inductance, eddy current losses, coil-to-ground and turn-to-turn capacitance, was synthesized from the experimental data. This magnet equivalent circuit can be used to predict the current ripple distribution along the superconducting magnet string and can provide dynamic information for the design of the collider current regulation loop
AC Power Local Network with Multiple Power Routers
Directory of Open Access Journals (Sweden)
Ryo Takahashi
2013-12-01
Full Text Available Controlling power flow and achieving appropriate matching between power sources and loads according to the quality of energy is expected to be one of the approaches to reduce wasted energy consumption. A power router, proposed recently, has the capability of realizing circuit switching in a power distribution network. This study focuses on the feasibility of an AC power routing network system composed of multiple power routers. To evaluate the feasibility, we experimentally confirm the circuit switching operation of the parallel and series configurations of the power routers, so that the network system can be designed by the combination of parallel and series configurations.
Measurement of ac electrical characteristics of SSC dipole magnets at Brookhaven
International Nuclear Information System (INIS)
Smedley, K.
1992-04-01
The SSC collider is designed to have circumference of 87 km. The superconducting magnets along the collider ring are grouped into ten sectors. Each sector, a string of average length of 8.7 km,m is powered by one power source located near the center of the sector. Because of the alternating-current (ac) electrical characteristics of the magnets, the power supply ripple currents and transients form a time and space distribution in the magnet string which affects particle motions. Additionally, since the power supply load is a magnet string, the current regulation loop design is highly dependent upon the ac electrical characteristics of the magnets. A means is needed to accurately determine the ac electrical characteristics of the superconducting magnets. The ac characteristics of magnets will be used to predict the ripple distribution of the long string of superconducting magnets. Magnet ac characteristics can also provide necessary information for the regulation loop design. This paper presents a method for measuring the ac characteristics of superconducting magnets. Two collider dipole magnets, one superconducting and one at room temperature, were tested at Brookhaven National Lab
Class of regular bouncing cosmologies
Vasilić, Milovan
2017-06-01
In this paper, I construct a class of everywhere regular geometric sigma models that possess bouncing solutions. Precisely, I show that every bouncing metric can be made a solution of such a model. My previous attempt to do so by employing one scalar field has failed due to the appearance of harmful singularities near the bounce. In this work, I use four scalar fields to construct a class of geometric sigma models which are free of singularities. The models within the class are parametrized by their background geometries. I prove that, whatever background is chosen, the dynamics of its small perturbations is classically stable on the whole time axis. Contrary to what one expects from the structure of the initial Lagrangian, the physics of background fluctuations is found to carry two tensor, two vector, and two scalar degrees of freedom. The graviton mass, which naturally appears in these models, is shown to be several orders of magnitude smaller than its experimental bound. I provide three simple examples to demonstrate how this is done in practice. In particular, I show that graviton mass can be made arbitrarily small.
A method for decreasing transport ac losses in multifilamentary and multistrip superconductors
Energy Technology Data Exchange (ETDEWEB)
Glowacki, B A [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Majoros, M [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom)
2000-07-01
A new method is proposed for decreasing transport ac losses in multifilamentary superconductors by the decoupling of the filaments using a magnetic material in the form of thin layers surrounding the individual filaments. For a superconductor with an elliptical cross section, the magnetic material surrounding the filaments affects the local magnetic field distribution that both reduces the critical current of the filaments and induces the transport ac losses in the magnetic material. Even by taking into account any detrimental influences of the presence of the magnetic material around the filaments, the analysis of the experimental data supported by computer modelling confirmed that for a Bi2223 tape with 100 filaments individually covered by magnetic material, such as iron powder, the transport ac losses should be 65 times lower than for the same multifilamentary conductor without the magnetic coating on the filaments. With an increasing number of filaments, the ac loss decrease would be even larger. (author)
A Dual-Buck–Boost AC/DC Converter for DC Nanogrid With Three Terminal Outputs
DEFF Research Database (Denmark)
Wu, Weimin; Wang, Houqing; Liu, Yuan
2017-01-01
Due to the widely used dc characterized loads and more distributed power generation sources, the dc nanogrid becomes more and more popular, and it is seen as an alternative to the ac grid. For safety considerations, the dc nanogrid should provide reliable grounding for the residential loads...... such as the low-voltage ac power system. There are three typical grounding configurations for a dc nanogrid: the united grounding, the unidirectional grounding, and the virtual isolated grounding. Each grounding configuration has its own specifications to ac/dc converters. In this paper, a dual-buck-boost ac/dc...... converter for use in the united-grounding-configuration-based dc nanogrid with three terminal outputs is proposed. The working principle of this converter is presented in detail through analyzing the equivalent circuits. Experiments are carried out to verify the theoretical analysis....
Autonomous Operation of Hybrid Microgrid with AC and DC Sub-Grids
DEFF Research Database (Denmark)
Loh, Poh Chiang; Blaabjerg, Frede
2011-01-01
the power flow among all the sources distributed throughout the two types of sub-grids, which certainly is tougher than previous efforts developed for only either ac or dc microgrid. This wider scope of control has not yet been investigated, and would certainly rely on the coordinated operation of dc...... sources, ac sources and interlinking converters. Suitable control and normalization schemes are therefore developed for controlling them with results presented for showing the overall performance of the hybrid microgrid.......This paper investigates on the active and reactive power sharing of an autonomous hybrid microgrid. Unlike existing microgrids which are purely ac, the hybrid microgrid studied here comprises dc and ac sub-grids, interconnected by power electronic interfaces. The main challenge here is to manage...
Design and synthesis of 225Ac radioimmunopharmaceuticals
International Nuclear Information System (INIS)
McDevitt, Michael R.; Ma, Dangshe; Simon, Jim; Frank, R. Keith; Scheinberg, David A.
2002-01-01
The alpha-particle-emitting radionuclides 213 Bi, 211 At, 224 Ra are under investigation for the treatment of leukemias, gliomas, and ankylosing spondylitis, respectively. 213 Bi and 211 At were attached to monoclonal antibodies and used as targeted immunotherapeutic agents while unconjugated 224 Ra chloride selectively seeks bone. 225 Ac possesses favorable physical properties for radioimmunotherapy (10 d half-life and 4 net alpha particles), but has a history of unfavorable radiolabeling chemistry and poor metal-chelate stability. We selected functionalized derivatives of DOTA as the most promising to pursue from out of a group of potential 225 Ac chelate compounds. A two-step synthetic process employing either MeO-DOTA-NCS or 2B-DOTA-NCS as the chelating moiety was developed to attach 225 Ac to monoclonal antibodies. This method was tested using several different IgG systems. The chelation reaction yield in the first step was 93±8% radiochemically pure (n=26). The second step yielded 225 Ac-DOTA-IgG constructs that were 95±5% radiochemically pure (n=27) and the mean percent immunoreactivity ranged from 25% to 81%, depending on the antibody used. This process has yielded several potential novel targeted 225 Ac-labeled immunotherapeutic agents that may now be evaluated in appropriate model systems and ultimately in humans
The relationship between synchronization and percolation for regular networks
Li, Zhe; Ren, Tao; Xu, Yanjie; Jin, Jianyu
2018-02-01
Synchronization and percolation are two essential phenomena in complex dynamical networks. They have been studied widely, but previously treated as unrelated. In this paper, the relationship between synchronization and percolation are revealed for regular networks. Firstly, we discovered a bridge between synchronization and percolation by using the eigenvalues of the Laplacian matrix to describe the synchronizability and using the eigenvalues of the adjacency matrix to describe the percolation threshold. Then, we proposed a method to find the relationship for regular networks based on the topology of networks. Particularly, if the degree distribution of the network is subject to delta function, we show that only the eigenvalues of the adjacency matrix need to be calculated. Finally, several examples are provided to demonstrate how to apply our proposed method to discover the relationship between synchronization and percolation for regular networks.
Selecting protein families for environmental features based on manifold regularization.
Jiang, Xingpeng; Xu, Weiwei; Park, E K; Li, Guangrong
2014-06-01
Recently, statistics and machine learning have been developed to identify functional or taxonomic features of environmental features or physiological status. Important proteins (or other functional and taxonomic entities) to environmental features can be potentially used as biosensors. A major challenge is how the distribution of protein and gene functions embodies the adaption of microbial communities across environments and host habitats. In this paper, we propose a novel regularization method for linear regression to adapt the challenge. The approach is inspired by local linear embedding (LLE) and we call it a manifold-constrained regularization for linear regression (McRe). The novel regularization procedure also has potential to be used in solving other linear systems. We demonstrate the efficiency and the performance of the approach in both simulation and real data.
Dynamics of coherent states in regular and chaotic regimes of the non-integrable Dicke model
Lerma-Hernández, S.; Chávez-Carlos, J.; Bastarrachea-Magnani, M. A.; López-del-Carpio, B.; Hirsch, J. G.
2018-04-01
The quantum dynamics of initial coherent states is studied in the Dicke model and correlated with the dynamics, regular or chaotic, of their classical limit. Analytical expressions for the survival probability, i.e. the probability of finding the system in its initial state at time t, are provided in the regular regions of the model. The results for regular regimes are compared with those of the chaotic ones. It is found that initial coherent states in regular regions have a much longer equilibration time than those located in chaotic regions. The properties of the distributions for the initial coherent states in the Hamiltonian eigenbasis are also studied. It is found that for regular states the components with no negligible contribution are organized in sequences of energy levels distributed according to Gaussian functions. In the case of chaotic coherent states, the energy components do not have a simple structure and the number of participating energy levels is larger than in the regular cases.
Directory of Open Access Journals (Sweden)
Hugo Nicasio Rodríguez Espínola
2001-06-01
Full Text Available Determinou-se o efeito de três doses de nutrientes minerais sobre o acúmulo e distribuição da matéria seca da planta de pepino tipo conserva, híbrido Crispina. As plantas foram cultivadas em sacolas plásticas com 4,6kg de substrato composto por uma mistura de 40% de casca de arroz e 60% de solo, no interior de uma estufa de polietileno, na primavera de 1998 e no verão de 1999. Foi empregado um delineamento experimental de blocos casualizados, com três repetições e 15 plantas por parcela. Os tratamentos foram constituídos por três níveis múltiplos de uma dose padrão de nutrientes aplicada para cada planta, contendo N-P-K-Ca e Mg nas quantidades de 0,8-0,12-0,8-0,46-0,086g.pl-1, com 0,33m de solução de micronutrientes e 0,07m de quelato de ferro. Os níveis corresponderam às quantidades de 50%, 100% e 150% da dose padrão, denominados de tratamentos T1, T2 e T3, respectivamente, aplicados semanalmente através da fertirrigação em todas as plantas de uma mesma parcela. Determinou-se a matéria seca dos diferentes órgãos da parte aérea da planta a intervalos semanais. Houve efeito significativo dos tratamentos no acúmulo da matéria seca, nos dois experimentos. A maior fração foi alocada para os frutos, atingindo o valor mais elevado de 0,64 na primavera. Concluiu-se que a distribuição da matéria seca desse material vegetal não é constante, sofrendo interações com as variáveis do ambiente.It was determined the effect of three mineral nutrient levels on dry matter accumulation and distribution of pickling cucumber plants, hybrid Crispina, grown inside a polyethylene greenhouse, in spring 1998 and in summer 1999. Planting was made in bags filled with 4.6kg of a substrate mixture composed by 40% rice husks and 60% soil. A randomized block experimental design was used, with three replications and15 plants per plot. A reference nutrient dose was supplied weekly to each one of the plants, with the following composition
Approaches to building single-stage AC/AC conversion switch-mode audio power amplifiers
DEFF Research Database (Denmark)
Ljusev, Petar; Andersen, Michael Andreas E.
2004-01-01
This paper discusses the possible topologies and promising approaches towards direct single-phase AC-AC conversion of the mains voltage for audio applications. When compared to standard Class-D switching audio power amplifiers with a separate power supply, it is expected that direct conversion...
Design and implementation of co-operative control strategy for hybrid AC/DC microgrids
Mahmud, Rasel
This thesis is mainly divided in two major sections: 1) Modeling and control of AC microgrid, DC microgrid, Hybrid AC/DC microgrid using distributed co-operative control, and 2) Development of a four bus laboratory prototype of an AC microgrid system. At first, a distributed cooperative control (DCC) for a DC microgrid considering the state-of-charge (SoC) of the batteries in a typical plug-in-electric-vehicle (PEV) is developed. In DC microgrids, this methodology is developed to assist the load sharing amongst the distributed generation units (DGs), according to their ratings with improved voltage regulation. Subsequently, a DCC based control algorithm for AC microgrid is also investigated to improve the performance of AC microgrid in terms of power sharing among the DGs, voltage regulation and frequency deviation. The results validate the advantages of the proposed methodology as compared to traditional droop control of AC microgrid. The DCC-based control methodology for AC microgrid and DC microgrid are further expanded to develop a DCC-based power management algorithm for hybrid AC/DC microgrid. The developed algorithm for hybrid microgrid controls the power flow through the interfacing converter (IC) between the AC and DC microgrids. This will facilitate the power sharing between the DGs according to their power ratings. Moreover, it enables the fixed scheduled power delivery at different operating conditions, while maintaining good voltage regulation and improved frequency profile. The second section provides a detailed explanation and step-by-step design and development of an AC/DC microgrid testbed. Controllers for the three-phase inverters are designed and tested on different generation units along with their corresponding inductor-capacitor-inductor (LCL) filters to eliminate the switching frequency harmonics. Electric power distribution line models are developed to form the microgrid network topology. Voltage and current sensors are placed in the proper
ac propulsion system for an electric vehicle
Geppert, S.
1980-01-01
It is pointed out that dc drives will be the logical choice for current production electric vehicles (EV). However, by the mid-80's, there is a good chance that the price and reliability of suitable high-power semiconductors will allow for a competitive ac system. The driving force behind the ac approach is the induction motor, which has specific advantages relative to a dc shunt or series traction motor. These advantages would be an important factor in the case of a vehicle for which low maintenance characteristics are of primary importance. A description of an EV ac propulsion system is provided, taking into account the logic controller, the inverter, the motor, and a two-speed transmission-differential-axle assembly. The main barrier to the employment of the considered propulsion system in EV is not any technical problem, but inverter transistor cost.
Superconducting three element synchronous ac machine
International Nuclear Information System (INIS)
Boyer, L.; Chabrerie, J.P.; Mailfert, A.; Renard, M.
1975-01-01
There is a growing interest in ac superconducting machines. Of several new concepts proposed for these machines in the last years one of the most promising seems to be the ''three elements'' concept which allows the cancellation of the torque acting on the superconducting field winding, thus overcoming some of the major contraints. This concept leads to a device of induction-type generator. A synchronous, three element superconducting ac machine is described, in which a room temperature, dc fed rotating winding is inserted between the superconducting field winding and the ac armature. The steady-state machine theory is developed, the flux linkages are established, and the torque expressions are derived. The condition for zero torque on the field winding, as well as the resulting electrical equations of the machine, are given. The theoretical behavior of the machine is studied, using phasor diagrams and assuming for the superconducting field winding either a constant current or a constant flux condition
International Nuclear Information System (INIS)
Mori, N.; Kobayashi, K.
1996-01-01
A two-dimensional neutron diffusion equation is solved for regular polygonal regions by the finite Fourier transformation, and geometrical bucklings are calculated for regular 3-10 polygonal regions. In the case of the regular triangular region, it is found that a simple and rigorous analytic solution is obtained for the geometrical buckling and the distribution of the neutron current along the outer boundary. (author)
21 CFR 886.4440 - AC-powered magnet.
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered magnet. 886.4440 Section 886.4440 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4440 AC-powered magnet. (a) Identification. An AC-powered magnet is an AC-powered device that generates a magnetic field intended to find and remove...
AC conductivity for a holographic Weyl semimetal
Energy Technology Data Exchange (ETDEWEB)
Grignani, Gianluca; Marini, Andrea; Peña-Benitez, Francisco; Speziali, Stefano [Dipartimento di Fisica e Geologia, Università di Perugia,I.N.F.N. Sezione di Perugia,Via Pascoli, I-06123 Perugia (Italy)
2017-03-23
We study the AC electrical conductivity at zero temperature in a holographic model for a Weyl semimetal. At small frequencies we observe a linear dependence in the frequency. The model shows a quantum phase transition between a topological semimetal (Weyl semimetal phase) with a non vanishing anomalous Hall conductivity and a trivial semimetal. The AC conductivity has an intermediate scaling due to the presence of a quantum critical region in the phase diagram of the system. The phase diagram is reconstructed using the scaling properties of the conductivity. We compare with the experimental data of https://www.doi.org/10.1103/PhysRevB.93.121110 obtaining qualitative agreement.
Mapa acústico parcial de Benetusser
MORILLA CASTELLANOS, EMILIO
2012-01-01
Se establece el mapa de ruido del municipio de Benetússer para evaluar y conocer su exposición al ruido ambiental y así poder dar cumplimiento a la Directiva Europea sobre Gestión y Evaluación de Ruido Ambiental (2002/49/CE) y a la Ley nacional 37/2003 del Ruido. Los mapas estratégicos de ruido nos aportan la información fundamental para diagnosticar la situación acústica y para la gestión del ruido ambiental. Morilla Castellanos, E. (2012). Mapa acústico parcial de Benetusser. http://h...
Preliminary study on AC superconducting machines
International Nuclear Information System (INIS)
Yamamoto, M.; Ishigohka, T.; Shimohka, T.; Mizukami, N.; Yamaguchi, M.
1988-01-01
This paper describes the issues involved in developing AC superconducting machines. In the first phase, as a preliminary experiment, a 4kVa AC superconducting coil which employs 100A class 50/60Hz superconductors is made and tested. And, in the second phase, as an extension of the 4kVa coil, a model superconducting transformer is made and examined. The transformer has a novel quench protection system with an auxiliary coil only in the low voltage side. The behavior of the overcurrent protection system is confirmed
Nuclear structure of {sup 231}Ac
Energy Technology Data Exchange (ETDEWEB)
Boutami, R. [Instituto de Estructura de la Materia, CSIC, Serrano 113 bis, E-28006 Madrid (Spain); Borge, M.J.G. [Instituto de Estructura de la Materia, CSIC, Serrano 113 bis, E-28006 Madrid (Spain)], E-mail: borge@iem.cfmac.csic.es; Mach, H. [Department of Radiation Sciences, ISV, Uppsala University, SE-751 21 Uppsala (Sweden); Kurcewicz, W. [Department of Physics, University of Warsaw, Pl-00 681 Warsaw (Poland); Fraile, L.M. [Departamento Fisica Atomica, Molecular y Nuclear, Facultad CC. Fisicas, Universidad Complutense, E-28040 Madrid (Spain); ISOLDE, PH Department, CERN, CH-1211 Geneva 23 (Switzerland); Gulda, K. [Department of Physics, University of Warsaw, Pl-00 681 Warsaw (Poland); Aas, A.J. [Department of Chemistry, University of Oslo, PO Box 1033, Blindern, N-0315 Oslo (Norway); Garcia-Raffi, L.M. [Instituto de Fisica Corpuscular, CSIC - Universidad de Valencia, Apdo. 22805, E-46071 Valencia (Spain); Lovhoiden, G. [Department of Physics, University of Oslo, PO Box 1048, Blindern, N-0316 Oslo (Norway); Martinez, T.; Rubio, B.; Tain, J.L. [Instituto de Fisica Corpuscular, CSIC - Universidad de Valencia, Apdo. 22805, E-46071 Valencia (Spain); Tengblad, O. [Instituto de Estructura de la Materia, CSIC, Serrano 113 bis, E-28006 Madrid (Spain); ISOLDE, PH Department, CERN, CH-1211 Geneva 23 (Switzerland)
2008-10-15
The low-energy structure of {sup 231}Ac has been investigated by means of {gamma} ray spectroscopy following the {beta}{sup -} decay of {sup 231}Ra. Multipolarities of 28 transitions have been established by measuring conversion electrons with a MINI-ORANGE electron spectrometer. The decay scheme of {sup 231}Ra {yields}{sup 231}Ac has been constructed for the first time. The Advanced Time Delayed {beta}{gamma}{gamma}(t) method has been used to measure the half-lives of five levels. The moderately fast B(E1) transition rates derived suggest that the octupole effects, albeit weak, are still present in this exotic nucleus.
Statistical time lags in ac discharges
International Nuclear Information System (INIS)
Sobota, A; Kanters, J H M; Van Veldhuizen, E M; Haverlag, M; Manders, F
2011-01-01
The paper presents statistical time lags measured for breakdown events in near-atmospheric pressure argon and xenon. Ac voltage at 100, 400 and 800 kHz was used to drive the breakdown processes, and the voltage amplitude slope was varied between 10 and 1280 V ms -1 . The values obtained for the statistical time lags are roughly between 1 and 150 ms. It is shown that the statistical time lags in ac-driven discharges follow the same general trends as the discharges driven by voltage of monotonic slope. In addition, the validity of the Cobine-Easton expression is tested at an alternating voltage form.
Statistical time lags in ac discharges
Energy Technology Data Exchange (ETDEWEB)
Sobota, A; Kanters, J H M; Van Veldhuizen, E M; Haverlag, M [Eindhoven University of Technology, Department of Applied Physics, Postbus 513, 5600MB Eindhoven (Netherlands); Manders, F, E-mail: a.sobota@tue.nl [Philips Lighting, LightLabs, Mathildelaan 1, 5600JM Eindhoven (Netherlands)
2011-04-06
The paper presents statistical time lags measured for breakdown events in near-atmospheric pressure argon and xenon. Ac voltage at 100, 400 and 800 kHz was used to drive the breakdown processes, and the voltage amplitude slope was varied between 10 and 1280 V ms{sup -1}. The values obtained for the statistical time lags are roughly between 1 and 150 ms. It is shown that the statistical time lags in ac-driven discharges follow the same general trends as the discharges driven by voltage of monotonic slope. In addition, the validity of the Cobine-Easton expression is tested at an alternating voltage form.
Geosocial process and its regularities
Vikulina, Marina; Vikulin, Alexander; Dolgaya, Anna
2015-04-01
Natural disasters and social events (wars, revolutions, genocides, epidemics, fires, etc.) accompany each other throughout human civilization, thus reflecting the close relationship of these phenomena that are seemingly of different nature. In order to study this relationship authors compiled and analyzed the list of the 2,400 natural disasters and social phenomena weighted by their magnitude that occurred during the last XXXVI centuries of our history. Statistical analysis was performed separately for each aggregate (natural disasters and social phenomena), and for particular statistically representative types of events. There was 5 + 5 = 10 types. It is shown that the numbers of events in the list are distributed by logarithmic law: the bigger the event, the less likely it happens. For each type of events and each aggregate the existence of periodicities with periods of 280 ± 60 years was established. Statistical analysis of the time intervals between adjacent events for both aggregates showed good agreement with Weibull-Gnedenko distribution with shape parameter less than 1, which is equivalent to the conclusion about the grouping of events at small time intervals. Modeling of statistics of time intervals with Pareto distribution allowed to identify the emergent property for all events in the aggregate. This result allowed the authors to make conclusion about interaction between natural disasters and social phenomena. The list of events compiled by authors and first identified properties of cyclicity, grouping and interaction process reflected by this list is the basis of modeling essentially unified geosocial process at high enough statistical level. Proof of interaction between "lifeless" Nature and Society is fundamental and provided a new approach to forecasting demographic crises with taking into account both natural disasters and social phenomena.
Higher derivative regularization and chiral anomaly
International Nuclear Information System (INIS)
Nagahama, Yoshinori.
1985-02-01
A higher derivative regularization which automatically leads to the consistent chiral anomaly is analyzed in detail. It explicitly breaks all the local gauge symmetry but preserves global chiral symmetry and leads to the chirally symmetric consistent anomaly. This regularization thus clarifies the physics content contained in the consistent anomaly. We also briefly comment on the application of this higher derivative regularization to massless QED. (author)
Regularity effect in prospective memory during aging
Directory of Open Access Journals (Sweden)
Geoffrey Blondelle
2016-10-01
Full Text Available Background: Regularity effect can affect performance in prospective memory (PM, but little is known on the cognitive processes linked to this effect. Moreover, its impacts with regard to aging remain unknown. To our knowledge, this study is the first to examine regularity effect in PM in a lifespan perspective, with a sample of young, intermediate, and older adults. Objective and design: Our study examined the regularity effect in PM in three groups of participants: 28 young adults (18–30, 16 intermediate adults (40–55, and 25 older adults (65–80. The task, adapted from the Virtual Week, was designed to manipulate the regularity of the various activities of daily life that were to be recalled (regular repeated activities vs. irregular non-repeated activities. We examine the role of several cognitive functions including certain dimensions of executive functions (planning, inhibition, shifting, and binding, short-term memory, and retrospective episodic memory to identify those involved in PM, according to regularity and age. Results: A mixed-design ANOVA showed a main effect of task regularity and an interaction between age and regularity: an age-related difference in PM performances was found for irregular activities (older < young, but not for regular activities. All participants recalled more regular activities than irregular ones with no age effect. It appeared that recalling of regular activities only involved planning for both intermediate and older adults, while recalling of irregular ones were linked to planning, inhibition, short-term memory, binding, and retrospective episodic memory. Conclusion: Taken together, our data suggest that planning capacities seem to play a major role in remembering to perform intended actions with advancing age. Furthermore, the age-PM-paradox may be attenuated when the experimental design is adapted by implementing a familiar context through the use of activities of daily living. The clinical
Regularity effect in prospective memory during aging
Blondelle, Geoffrey; Hainselin, Mathieu; Gounden, Yannick; Heurley, Laurent; Voisin, Hélène; Megalakaki, Olga; Bressous, Estelle; Quaglino, Véronique
2016-01-01
Background: Regularity effect can affect performance in prospective memory (PM), but little is known on the cognitive processes linked to this effect. Moreover, its impacts with regard to aging remain unknown. To our knowledge, this study is the first to examine regularity effect in PM in a lifespan perspective, with a sample of young, intermediate, and older adults.Objective and design: Our study examined the regularity effect in PM in three groups of participants: 28 young adults (18–30), 1...
Iterative Regularization with Minimum-Residual Methods
DEFF Research Database (Denmark)
Jensen, Toke Koldborg; Hansen, Per Christian
2007-01-01
subspaces. We provide a combination of theory and numerical examples, and our analysis confirms the experience that MINRES and MR-II can work as general regularization methods. We also demonstrate theoretically and experimentally that the same is not true, in general, for GMRES and RRGMRES their success......We study the regularization properties of iterative minimum-residual methods applied to discrete ill-posed problems. In these methods, the projection onto the underlying Krylov subspace acts as a regularizer, and the emphasis of this work is on the role played by the basis vectors of these Krylov...... as regularization methods is highly problem dependent....
Iterative regularization with minimum-residual methods
DEFF Research Database (Denmark)
Jensen, Toke Koldborg; Hansen, Per Christian
2006-01-01
subspaces. We provide a combination of theory and numerical examples, and our analysis confirms the experience that MINRES and MR-II can work as general regularization methods. We also demonstrate theoretically and experimentally that the same is not true, in general, for GMRES and RRGMRES - their success......We study the regularization properties of iterative minimum-residual methods applied to discrete ill-posed problems. In these methods, the projection onto the underlying Krylov subspace acts as a regularizer, and the emphasis of this work is on the role played by the basis vectors of these Krylov...... as regularization methods is highly problem dependent....
An adaptive regularization parameter choice strategy for multispectral bioluminescence tomography
Energy Technology Data Exchange (ETDEWEB)
Feng Jinchao; Qin Chenghu; Jia Kebin; Han Dong; Liu Kai; Zhu Shouping; Yang Xin; Tian Jie [Medical Image Processing Group, Institute of Automation, Chinese Academy of Sciences, P. O. Box 2728, Beijing 100190 (China); College of Electronic Information and Control Engineering, Beijing University of Technology, Beijing 100124 (China); Medical Image Processing Group, Institute of Automation, Chinese Academy of Sciences, P. O. Box 2728, Beijing 100190 (China); Medical Image Processing Group, Institute of Automation, Chinese Academy of Sciences, P. O. Box 2728, Beijing 100190 (China) and School of Life Sciences and Technology, Xidian University, Xi' an 710071 (China)
2011-11-15
Purpose: Bioluminescence tomography (BLT) provides an effective tool for monitoring physiological and pathological activities in vivo. However, the measured data in bioluminescence imaging are corrupted by noise. Therefore, regularization methods are commonly used to find a regularized solution. Nevertheless, for the quality of the reconstructed bioluminescent source obtained by regularization methods, the choice of the regularization parameters is crucial. To date, the selection of regularization parameters remains challenging. With regards to the above problems, the authors proposed a BLT reconstruction algorithm with an adaptive parameter choice rule. Methods: The proposed reconstruction algorithm uses a diffusion equation for modeling the bioluminescent photon transport. The diffusion equation is solved with a finite element method. Computed tomography (CT) images provide anatomical information regarding the geometry of the small animal and its internal organs. To reduce the ill-posedness of BLT, spectral information and the optimal permissible source region are employed. Then, the relationship between the unknown source distribution and multiview and multispectral boundary measurements is established based on the finite element method and the optimal permissible source region. Since the measured data are noisy, the BLT reconstruction is formulated as l{sub 2} data fidelity and a general regularization term. When choosing the regularization parameters for BLT, an efficient model function approach is proposed, which does not require knowledge of the noise level. This approach only requests the computation of the residual and regularized solution norm. With this knowledge, we construct the model function to approximate the objective function, and the regularization parameter is updated iteratively. Results: First, the micro-CT based mouse phantom was used for simulation verification. Simulation experiments were used to illustrate why multispectral data were used
Regularization of the Coulomb scattering problem
International Nuclear Information System (INIS)
Baryshevskii, V.G.; Feranchuk, I.D.; Kats, P.B.
2004-01-01
The exact solution of the Schroedinger equation for the Coulomb potential is used within the scope of both stationary and time-dependent scattering theories in order to find the parameters which determine the regularization of the Rutherford cross section when the scattering angle tends to zero but the distance r from the center remains finite. The angular distribution of the particles scattered in the Coulomb field is studied on rather a large but finite distance r from the center. It is shown that the standard asymptotic representation of the wave functions is inapplicable in the case when small scattering angles are considered. The unitary property of the scattering matrix is analyzed and the 'optical' theorem for this case is discussed. The total and transport cross sections for scattering the particle by the Coulomb center proved to be finite values and are calculated in the analytical form. It is shown that the effects under consideration can be important for the observed characteristics of the transport processes in semiconductors which are determined by the electron and hole scattering by the field of charged impurity centers
TRANSIENT LUNAR PHENOMENA: REGULARITY AND REALITY
International Nuclear Information System (INIS)
Crotts, Arlin P. S.
2009-01-01
Transient lunar phenomena (TLPs) have been reported for centuries, but their nature is largely unsettled, and even their existence as a coherent phenomenon is controversial. Nonetheless, TLP data show regularities in the observations; a key question is whether this structure is imposed by processes tied to the lunar surface, or by terrestrial atmospheric or human observer effects. I interrogate an extensive catalog of TLPs to gauge how human factors determine the distribution of TLP reports. The sample is grouped according to variables which should produce differing results if determining factors involve humans, and not reflecting phenomena tied to the lunar surface. Features dependent on human factors can then be excluded. Regardless of how the sample is split, the results are similar: ∼50% of reports originate from near Aristarchus, ∼16% from Plato, ∼6% from recent, major impacts (Copernicus, Kepler, Tycho, and Aristarchus), plus several at Grimaldi. Mare Crisium produces a robust signal in some cases (however, Crisium is too large for a 'feature' as defined). TLP count consistency for these features indicates that ∼80% of these may be real. Some commonly reported sites disappear from the robust averages, including Alphonsus, Ross D, and Gassendi. These reports begin almost exclusively after 1955, when TLPs became widely known and many more (and inexperienced) observers searched for TLPs. In a companion paper, we compare the spatial distribution of robust TLP sites to transient outgassing (seen by Apollo and Lunar Prospector instruments). To a high confidence, robust TLP sites and those of lunar outgassing correlate strongly, further arguing for the reality of TLPs.
Effects of AC Electric Field on Small Laminar Nonpremixed Flames
Xiong, Yuan
2015-04-01
Electric field can be a viable method in controlling various combustion properties. Comparing to traditional actuators, an application of electric field requires very small power consumption. Especially, alternating current (AC) has received attention recently, since it could modulate flames appreciably even for the cases when direct current (DC) has minimal effects. In this study, the effect of AC electric fields on small coflow diffusion flames is focused with applications of various laser diagnostic techniques. Flow characteristics of baseline diffusion flames, which corresponds to stationary small coflow diffusion flames when electric field is not applied, were firstly investigated with a particular focus on the flow field in near-nozzle region with the buoyancy force exerted on fuels due to density differences among fuel, ambient air, and burnt gas. The result showed that the buoyancy force exerted on the fuel as well as on burnt gas significantly distorted the near-nozzle flow-fields. In the fuels with densities heavier than air, recirculation zones were formed very close to the nozzle exit. Nozzle heating effect influenced this near-nozzle flow-field particularly among lighter fuels. Numerical simulations were also conducted and the results showed that a fuel inlet boundary condition with a fully developed velocity profile for cases with long fuel tubes should be specified inside the fuel tube to obtain satisfactory agreement in both the flow and temperature fields with those from experiment. With sub-critical AC applied to the baseline flames, particle image velocimetry (PIV), light scattering, laser-induced incandescence (LII), and laser-induced fluores- cence (LIF) techniques were adopted to identify the flow field and the structures of OH, polycyclic aromatic hydrocarbons (PAHs), soot zone. Under certain AC condi- tions of applied voltage and frequency, the distribution of PAHs and the flow field near the nozzle exit were drastically altered from the
AC loss in superconducting tapes and cables
Oomen, M.P.
2000-01-01
The present study discusses the AC loss in high-temperature superconductors. Superconducting materials with a relatively high critical temperature were discovered in 1986. They are presently developed for use in large-scale power-engineering devices such as power-transmission cables, transformers
Composite Based EHV AC Overhead Transmission Lines
DEFF Research Database (Denmark)
Sørensen, Thomas Kjærsgaard
and analysed with regard to the possibilities, limitations and risks widespread application of composite materials on EHV AC overhead transmission lines may present. To form the basis for evaluation of the useability of composite materials, dierent overhead line projects aimed at reducing the environmental...
Ac-dc converter firing error detection
International Nuclear Information System (INIS)
Gould, O.L.
1996-01-01
Each of the twelve Booster Main Magnet Power Supply modules consist of two three-phase, full-wave rectifier bridges in series to provide a 560 VDC maximum output. The harmonic contents of the twelve-pulse ac-dc converter output are multiples of the 60 Hz ac power input, with a predominant 720 Hz signal greater than 14 dB in magnitude above the closest harmonic components at maximum output. The 720 Hz harmonic is typically greater than 20 dB below the 500 VDC output signal under normal operation. Extracting specific harmonics from the rectifier output signal of a 6, 12, or 24 pulse ac-dc converter allows the detection of SCR firing angle errors or complete misfires. A bandpass filter provides the input signal to a frequency-to-voltage converter. Comparing the output of the frequency-to-voltage converter to a reference voltage level provides an indication of the magnitude of the harmonics in the ac-dc converter output signal
THE ACS NEARBY GALAXY SURVEY TREASURY
International Nuclear Information System (INIS)
Dalcanton, Julianne J.; Williams, Benjamin F.; Rosema, Keith; Gogarten, Stephanie M.; Christensen, Charlotte; Gilbert, Karoline; Hodge, Paul; Seth, Anil C.; Dolphin, Andrew; Holtzman, Jon; Skillman, Evan D.; Weisz, Daniel; Cole, Andrew; Girardi, Leo; Karachentsev, Igor D.; Olsen, Knut; Freeman, Ken; Gallart, Carme; Harris, Jason; De Jong, Roelof S.
2009-01-01
The ACS Nearby Galaxy Survey Treasury (ANGST) is a systematic survey to establish a legacy of uniform multi-color photometry of resolved stars for a volume-limited sample of nearby galaxies (D 4 in luminosity and star formation rate. The survey data consist of images taken with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST), supplemented with archival data and new Wide Field Planetary Camera 2 (WFPC2) imaging taken after the failure of ACS. Survey images include wide field tilings covering the full radial extent of each galaxy, and single deep pointings in uncrowded regions of the most massive galaxies in the volume. The new wide field imaging in ANGST reaches median 50% completenesses of m F475W = 28.0 mag, m F606W = 27.3 mag, and m F814W = 27.3 mag, several magnitudes below the tip of the red giant branch (TRGB). The deep fields reach magnitudes sufficient to fully resolve the structure in the red clump. The resulting photometric catalogs are publicly accessible and contain over 34 million photometric measurements of >14 million stars. In this paper we present the details of the sample selection, imaging, data reduction, and the resulting photometric catalogs, along with an analysis of the photometric uncertainties (systematic and random), for both ACS and WFPC2 imaging. We also present uniformly derived relative distances measured from the apparent magnitude of the TRGB.
Meso Mechanical Analysis of AC Mixture Response
Woldekidan, M.F.; Huurman, M.; Vaccari, E.; Poot, M.
2012-01-01
Ongoing research into performance modeling of Asphalt Concrete (AC) mixtures using meso mechanics approaches is being undertaken at Delft University of Technology (TUD). The approach has already been successfully employed for evaluating the long term performance of porous asphalt concrete. The work
AC relaxation in the iron(8) molecular magnet
Rose, Geordie
2000-11-01
We investigate the low energy magnetic relaxation characteristics of the ``iron eight'' (Fe8) molecular magnet. Each molecule in this material contains a cluster of eight Fe 3+ ions surrounded by organic ligands. The molecules arrange themselves into a regular lattice with triclinic symmetry. At sufficiently low energies, the electronic spins of the Fe3+ ions lock together into a ``quantum rotator'' with spin S = 10. We derive a low energy effective Hamiltonian for this system, valid for temperatures less than Tc ~ 360 mK , where Tc is the temperature at which the Fe8 system crosses over into a ``quantum regime'' where relaxation characteristics become temperature independent. We show that in this regime the dominant environmental coupling is to the environmental spin bath in the molecule. We show how to explicitly calculate these couplings, given crystallographic information about the molecule, and do this for Fe8. We use this information to calculate the linewidth, topological decoherence and orthogonality blocking parameters. All of these quantities are shown to exhibit an isotope effect. We demonstrate that orthogonality blocking in Fe8 is significant and suppresses coherent tunneling. We then use our low energy effective Hamiltonian to calculate the single-molecule relaxation rate in the presence of an external magnetic field with both AC and DC components by solving the Landau-Zener problem in the presence of a nuclear spin bath. Both sawtooth and sinusoidal AC fields are analyzed. This single-molecule relaxation rate is then used as input into a master equation in order to take into account the many-molecule nature of the full system. Our results are then compared to quantum regime relaxation experiments performed on the Fe8 system.
AC magnetic transport on heterogeneous ferromagnetic wires and tubes
International Nuclear Information System (INIS)
Sinnecker, J.P.; Pirota, K.R.; Knobel, M.; Kraus, L.
2002-01-01
The AC current density radial distribution is calculated on heterogeneous composite materials with cylindrical geometry. The composites have an inner core and thin outer shell that can be either from the same material (homogenous material like simple wires) or from different materials with different physical properties. The case in which a non-magnetic inner core is surrounded by a magnetic layer, like electrodeposited wires, is mainly studied. The effect of frequency and applied magnetic field is simulated. The current density distribution as a function of frequency and applied field, as well as the total current over the inner core and outer shells are calculated. The results agree substantially well with the experimentally observed data for simple electrodeposited wires
Study of the AC machines winding having fractional q
Bespalov, V. Y.; Sidorov, A. O.
2018-02-01
The winding schemes with a fractional numbers of slots per pole and phase q have been known and used for a long time. However, in the literature on the low-noise machines design there are not recommended to use. Nevertheless, fractional q windings have been realized in many applications of special AC electrical machines, allowing to improve their performance, including vibroacoustic one. This paper deals with harmonic analysis of windings having integer and fractional q in permanent magnet synchronous motors, a comparison of their characteristics is performed, frequencies of subharmonics are revealed. Optimal winding pitch design is found giving reduce the amplitudes of subharmonics. Distribution factors for subharmonics, fractional and high-order harmonics are calculated, results analysis is represented, allowing for giving recommendations how to calculate distribution factors for different harmonics when q is fractional.
Regularization parameter selection methods for ill-posed Poisson maximum likelihood estimation
International Nuclear Information System (INIS)
Bardsley, Johnathan M; Goldes, John
2009-01-01
In image processing applications, image intensity is often measured via the counting of incident photons emitted by the object of interest. In such cases, image data noise is accurately modeled by a Poisson distribution. This motivates the use of Poisson maximum likelihood estimation for image reconstruction. However, when the underlying model equation is ill-posed, regularization is needed. Regularized Poisson likelihood estimation has been studied extensively by the authors, though a problem of high importance remains: the choice of the regularization parameter. We will present three statistically motivated methods for choosing the regularization parameter, and numerical examples will be presented to illustrate their effectiveness
Manifold regularized multitask feature learning for multimodality disease classification.
Jie, Biao; Zhang, Daoqiang; Cheng, Bo; Shen, Dinggang
2015-02-01
Multimodality based methods have shown great advantages in classification of Alzheimer's disease (AD) and its prodromal stage, that is, mild cognitive impairment (MCI). Recently, multitask feature selection methods are typically used for joint selection of common features across multiple modalities. However, one disadvantage of existing multimodality based methods is that they ignore the useful data distribution information in each modality, which is essential for subsequent classification. Accordingly, in this paper we propose a manifold regularized multitask feature learning method to preserve both the intrinsic relatedness among multiple modalities of data and the data distribution information in each modality. Specifically, we denote the feature learning on each modality as a single task, and use group-sparsity regularizer to capture the intrinsic relatedness among multiple tasks (i.e., modalities) and jointly select the common features from multiple tasks. Furthermore, we introduce a new manifold-based Laplacian regularizer to preserve the data distribution information from each task. Finally, we use the multikernel support vector machine method to fuse multimodality data for eventual classification. Conversely, we also extend our method to the semisupervised setting, where only partial data are labeled. We evaluate our method using the baseline magnetic resonance imaging (MRI), fluorodeoxyglucose positron emission tomography (FDG-PET), and cerebrospinal fluid (CSF) data of subjects from AD neuroimaging initiative database. The experimental results demonstrate that our proposed method can not only achieve improved classification performance, but also help to discover the disease-related brain regions useful for disease diagnosis. © 2014 Wiley Periodicals, Inc.
A regularized stationary mean-field game
Yang, Xianjin
2016-01-01
In the thesis, we discuss the existence and numerical approximations of solutions of a regularized mean-field game with a low-order regularization. In the first part, we prove a priori estimates and use the continuation method to obtain the existence of a solution with a positive density. Finally, we introduce the monotone flow method and solve the system numerically.
A regularized stationary mean-field game
Yang, Xianjin
2016-04-19
In the thesis, we discuss the existence and numerical approximations of solutions of a regularized mean-field game with a low-order regularization. In the first part, we prove a priori estimates and use the continuation method to obtain the existence of a solution with a positive density. Finally, we introduce the monotone flow method and solve the system numerically.
On infinite regular and chiral maps
Arredondo, John A.; Valdez, Camilo Ramírez y Ferrán
2015-01-01
We prove that infinite regular and chiral maps take place on surfaces with at most one end. Moreover, we prove that an infinite regular or chiral map on an orientable surface with genus can only be realized on the Loch Ness monster, that is, the topological surface of infinite genus with one end.
From recreational to regular drug use
DEFF Research Database (Denmark)
Järvinen, Margaretha; Ravn, Signe
2011-01-01
This article analyses the process of going from recreational use to regular and problematic use of illegal drugs. We present a model containing six career contingencies relevant for young people’s progress from recreational to regular drug use: the closing of social networks, changes in forms...
Automating InDesign with Regular Expressions
Kahrel, Peter
2006-01-01
If you need to make automated changes to InDesign documents beyond what basic search and replace can handle, you need regular expressions, and a bit of scripting to make them work. This Short Cut explains both how to write regular expressions, so you can find and replace the right things, and how to use them in InDesign specifically.
Regularization modeling for large-eddy simulation
Geurts, Bernardus J.; Holm, D.D.
2003-01-01
A new modeling approach for large-eddy simulation (LES) is obtained by combining a "regularization principle" with an explicit filter and its inversion. This regularization approach allows a systematic derivation of the implied subgrid model, which resolves the closure problem. The central role of
2010-07-01
... employee under subsection (a) or in excess of the employee's normal working hours or regular working hours... Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR STATEMENTS OF GENERAL POLICY OR... not less than one and one-half times their regular rates of pay. Section 7(e) of the Act defines...
Energy Technology Data Exchange (ETDEWEB)
Dall' Anese, Emiliano; Simonetto, Andrea; Dhople, Sairaj
2016-12-29
This paper focuses on power distribution networks featuring inverter-interfaced distributed energy resources (DERs), and develops feedback controllers that drive the DER output powers to solutions of time-varying AC optimal power flow (OPF) problems. Control synthesis is grounded on primal-dual-type methods for regularized Lagrangian functions, as well as linear approximations of the AC power-flow equations. Convergence and OPF-solution-tracking capabilities are established while acknowledging: i) communication-packet losses, and ii) partial updates of control signals. The latter case is particularly relevant since it enables asynchronous operation of the controllers where DER setpoints are updated at a fast time scale based on local voltage measurements, and information on the network state is utilized if and when available, based on communication constraints. As an application, the paper considers distribution systems with high photovoltaic integration, and demonstrates that the proposed framework provides fast voltage-regulation capabilities, while enabling the near real-time pursuit of solutions of AC OPF problems.
Energy Technology Data Exchange (ETDEWEB)
Dall' Anese, Emiliano; Simonetto, Andrea; Dhople, Sairaj
2016-12-01
This paper focuses on power distribution networks featuring inverter-interfaced distributed energy resources (DERs), and develops feedback controllers that drive the DER output powers to solutions of time-varying AC optimal power flow (OPF) problems. Control synthesis is grounded on primal-dual-type methods for regularized Lagrangian functions, as well as linear approximations of the AC power-flow equations. Convergence and OPF-solution-tracking capabilities are established while acknowledging: i) communication-packet losses, and ii) partial updates of control signals. The latter case is particularly relevant since it enables asynchronous operation of the controllers where DER setpoints are updated at a fast time scale based on local voltage measurements, and information on the network state is utilized if and when available, based on communication constraints. As an application, the paper considers distribution systems with high photovoltaic integration, and demonstrates that the proposed framework provides fast voltage-regulation capabilities, while enabling the near real-time pursuit of solutions of AC OPF problems.
Assay Methods for ACS Activity and ACS Phosphorylation by MAP Kinases In Vitro and In Vivo.
Han, Xiaomin; Li, Guojing; Zhang, Shuqun
2017-01-01
Ethylene, a gaseous phytohormone, has profound effects on plant growth, development, and adaptation to the environment. Ethylene-regulated processes begin with the induction of ethylene biosynthesis. There are two key steps in ethylene biosynthesis. The first is the biosynthesis of 1-aminocyclopropane-1-carboxylic acid (ACC) from S-Adenosyl-Methionine (SAM), a common precursor in many metabolic pathways, which is catalyzed by ACC synthase (ACS). The second is the oxidative cleavage of ACC to form ethylene under the action of ACC oxidase (ACO). ACC biosynthesis is the committing and generally the rate-limiting step in ethylene biosynthesis. As a result, characterizing the cellular ACS activity and understanding its regulation are important. In this chapter, we detail the methods used to measure, (1) the enzymatic activity of both recombinant and native ACS proteins, and (2) the phosphorylation of ACS protein by mitogen-activated protein kinases (MAPKs) in vivo and in vitro.
Abbas, Qamar; Béguin, François
2016-06-01
We demonstrate that an activated carbon (AC)-based electrochemical capacitor implementing aqueous lithium sulfate electrolyte in 7:3 vol:vol water/methanol mixture can operate down to -40 °C with good electrochemical performance. Three-electrode cell investigations show that the faradaic contributions related with hydrogen chemisorption in the negative AC electrode are thermodynamically unfavored at -40 °C, enabling the system to work as a typical electrical double-layer (EDL) capacitor. After prolonged floating of the AC/AC capacitor at 1.6 V and -40°C, the capacitance, equivalent series resistance and efficiency remain constant, demonstrating the absence of ageing related with side redox reactions at this temperature. Interestingly, when temperature is increased back to 24 °C, the redox behavior due to hydrogen storage reappears and the system behaves as a freshly prepared one.
Digital model for harmonic interactions in AC/DC/AC systems
Energy Technology Data Exchange (ETDEWEB)
Guarini, A P; Rangel, R D; Pilotto, L A.S.; Pinto, R J; Passos, Junior, R [Centro de Pesquisas de Energia Eletrica (CEPEL), Rio de Janeiro, RJ (Brazil)
1994-12-31
The main purpose of this paper is to present a model for calculation of HVdc converter harmonics taking into account the influence of the harmonic interactions between the ac systems in dc link transmissions. The ideas and methodologies used in the model development take into account the dc current ripple and ac voltage distortion in the ac systems. The theory of switching functions is applied to contemplate for the frequency conversions between the ac and dc sides, in an iterative process. It is possible then to obtain, even in balanced situations, non-characteristic harmonics that are produced by frequencies originated in the other terminal, which can be significant in a strongly coupled system, such as back-to-back configuration. (author) 9 refs., 3 figs.
Approaches to building single-stage AC/AC conversion switch-mode audio power amplifiers
Energy Technology Data Exchange (ETDEWEB)
Ljusev, P.; Andersen, Michael A.E.
2005-07-01
This paper discusses the possible topologies and promising approaches towards direct single-phase AC-AC conversion of the mains voltage for audio applications. When compared to standard Class-D switching audio power amplifiers with a separate power supply, it is expected that direct conversion will provide better efficiency and higher level of integration, leading to lower component count, volume and cost, but at the expense of a minor performance deterioration. (au)
International Nuclear Information System (INIS)
Alili, Smail; Rugh, Hans Henrik
2008-01-01
We consider a supercritical branching process in time-dependent environment ξ. We assume that the offspring distributions depend regularly (C k or real-analytically) on real parameters λ. We show that the extinction probability q λ (ξ), given the environment ξ 'inherits' this regularity whenever the offspring distributions satisfy a condition of contraction-type. Our proof makes use of the Poincaré metric on the complex unit disc and a real-analytic implicit function theorem
DEFF Research Database (Denmark)
Wu, Dan; Tang, Fen; Dragicevic, Tomislav
2014-01-01
In an islanded AC microgrid with distributed energy storage system (ESS), photovoltaic (PV) generation and loads, a coordinated active power regulation is required to ensure efficient utilization of renewable energy, while keeping the ESS from overcharge and over discharge conditions. In this paper...
An iterative method for Tikhonov regularization with a general linear regularization operator
Hochstenbach, M.E.; Reichel, L.
2010-01-01
Tikhonov regularization is one of the most popular approaches to solve discrete ill-posed problems with error-contaminated data. A regularization operator and a suitable value of a regularization parameter have to be chosen. This paper describes an iterative method, based on Golub-Kahan
Regularization Techniques for Linear Least-Squares Problems
Suliman, Mohamed
2016-04-01
Linear estimation is a fundamental branch of signal processing that deals with estimating the values of parameters from a corrupted measured data. Throughout the years, several optimization criteria have been used to achieve this task. The most astonishing attempt among theses is the linear least-squares. Although this criterion enjoyed a wide popularity in many areas due to its attractive properties, it appeared to suffer from some shortcomings. Alternative optimization criteria, as a result, have been proposed. These new criteria allowed, in one way or another, the incorporation of further prior information to the desired problem. Among theses alternative criteria is the regularized least-squares (RLS). In this thesis, we propose two new algorithms to find the regularization parameter for linear least-squares problems. In the constrained perturbation regularization algorithm (COPRA) for random matrices and COPRA for linear discrete ill-posed problems, an artificial perturbation matrix with a bounded norm is forced into the model matrix. This perturbation is introduced to enhance the singular value structure of the matrix. As a result, the new modified model is expected to provide a better stabilize substantial solution when used to estimate the original signal through minimizing the worst-case residual error function. Unlike many other regularization algorithms that go in search of minimizing the estimated data error, the two new proposed algorithms are developed mainly to select the artifcial perturbation bound and the regularization parameter in a way that approximately minimizes the mean-squared error (MSE) between the original signal and its estimate under various conditions. The first proposed COPRA method is developed mainly to estimate the regularization parameter when the measurement matrix is complex Gaussian, with centered unit variance (standard), and independent and identically distributed (i.i.d.) entries. Furthermore, the second proposed COPRA
Regular graph construction for semi-supervised learning
International Nuclear Information System (INIS)
Vega-Oliveros, Didier A; Berton, Lilian; Eberle, Andre Mantini; Lopes, Alneu de Andrade; Zhao, Liang
2014-01-01
Semi-supervised learning (SSL) stands out for using a small amount of labeled points for data clustering and classification. In this scenario graph-based methods allow the analysis of local and global characteristics of the available data by identifying classes or groups regardless data distribution and representing submanifold in Euclidean space. Most of methods used in literature for SSL classification do not worry about graph construction. However, regular graphs can obtain better classification accuracy compared to traditional methods such as k-nearest neighbor (kNN), since kNN benefits the generation of hubs and it is not appropriate for high-dimensionality data. Nevertheless, methods commonly used for generating regular graphs have high computational cost. We tackle this problem introducing an alternative method for generation of regular graphs with better runtime performance compared to methods usually find in the area. Our technique is based on the preferential selection of vertices according some topological measures, like closeness, generating at the end of the process a regular graph. Experiments using the global and local consistency method for label propagation show that our method provides better or equal classification rate in comparison with kNN
Hierarchical regular small-world networks
International Nuclear Information System (INIS)
Boettcher, Stefan; Goncalves, Bruno; Guclu, Hasan
2008-01-01
Two new networks are introduced that resemble small-world properties. These networks are recursively constructed but retain a fixed, regular degree. They possess a unique one-dimensional lattice backbone overlaid by a hierarchical sequence of long-distance links, mixing real-space and small-world features. Both networks, one 3-regular and the other 4-regular, lead to distinct behaviors, as revealed by renormalization group studies. The 3-regular network is planar, has a diameter growing as √N with system size N, and leads to super-diffusion with an exact, anomalous exponent d w = 1.306..., but possesses only a trivial fixed point T c = 0 for the Ising ferromagnet. In turn, the 4-regular network is non-planar, has a diameter growing as ∼2 √(log 2 N 2 ) , exhibits 'ballistic' diffusion (d w = 1), and a non-trivial ferromagnetic transition, T c > 0. It suggests that the 3-regular network is still quite 'geometric', while the 4-regular network qualifies as a true small world with mean-field properties. As an engineering application we discuss synchronization of processors on these networks. (fast track communication)
Coupling regularizes individual units in noisy populations
International Nuclear Information System (INIS)
Ly Cheng; Ermentrout, G. Bard
2010-01-01
The regularity of a noisy system can modulate in various ways. It is well known that coupling in a population can lower the variability of the entire network; the collective activity is more regular. Here, we show that diffusive (reciprocal) coupling of two simple Ornstein-Uhlenbeck (O-U) processes can regularize the individual, even when it is coupled to a noisier process. In cellular networks, the regularity of individual cells is important when a select few play a significant role. The regularizing effect of coupling surprisingly applies also to general nonlinear noisy oscillators. However, unlike with the O-U process, coupling-induced regularity is robust to different kinds of coupling. With two coupled noisy oscillators, we derive an asymptotic formula assuming weak noise and coupling for the variance of the period (i.e., spike times) that accurately captures this effect. Moreover, we find that reciprocal coupling can regularize the individual period of higher dimensional oscillators such as the Morris-Lecar and Brusselator models, even when coupled to noisier oscillators. Coupling can have a counterintuitive and beneficial effect on noisy systems. These results have implications for the role of connectivity with noisy oscillators and the modulation of variability of individual oscillators.
Faradaic AC Electrokinetic Flow and Particle Traps
Ben, Yuxing; Chang, Hsueh-Chia
2004-11-01
Faradaic reaction at higher voltages can produce co-ion polarization at AC electrodes instead of counter-ion polarization due to capacitive charging from the bulk. The Faradaic co-ion polarization also does not screen the external field and hence can produce large net electro-kinetic flows at frequencies lower than the inverse RC time of the double layer. Due to the opposite polarization of capacitve and Faradaic charging, we can reverse the direction of AC flows on electrodes by changing the voltage and frequency. Particles and bacteria are trapped and then dispersed at stagnation lines, at locations predicted by our theory, by using these two flows sequentially. This technique offers a good way to concentrate and detect bacteria.
AC application of second generation HTS wire
Thieme, C. L. H.; Gagnon, K.; Voccio, J.; Aized, D.; Claassen, J.
2008-02-01
For the production of Second Generation (2G) YBCO High Temperature Superconductor wire American Superconductor uses a wide-strip MOD-YBCO/RABiTSTM process, a low-cost approach for commercial manufacturing. It can be engineered with a high degree of flexibility to manufacture practical 2G conductors with architectures and properties tailored for specific applications and operating conditions. For ac applications conductor and coil design can be geared towards low hysteretic losses. For applications which experience high frequency ac fields, the stabilizer needs to be adjusted for low eddy current losses. For these applications a stainless-steel laminate is used. An example is a Low Pass Filter Inductor which was developed and built in this work.
Aging, Counterfeiting Configuration Control (AC3)
2010-01-31
Systems Intergrated Into AC3 CABS - Common As-Built System PRISM - Process Re-inventing Integration Systems for Manufacturing PDM - Product Data...looks forward to deploying the completed tool at Raytheon in a true production environment, for as much as we like the challenge associated with...performance of DoD systems. DoD systems are particularly susceptible to intrusion of counterfeit parts, especially during surge and extended production
The LHC AC Dipole system: an introduction
Serrano, J; CERN. Geneva. BE Department
2010-01-01
The LHC AC Dipole is an instrument to study properties of the LHC lattice by inducing large transverse displacements in the beam. These displacements are generated by exciting the beam with an oscillating magnetic field at a frequency close to the tune. This paper presents the system requirements and the technical solution chosen to meet them, based of high-power audio amplifiers and a resonant parallel RLC circuit.
Modeling photovoltaic systems for AC appliances
Directory of Open Access Journals (Sweden)
Andreea Maria Neaca
2009-10-01
Full Text Available In this paper is described the development of a model which can simulate the performance of a photovoltaic (PV system under specific meteorological conditions and transforming the DC current into AC current. In this model, the accent stands on the design of a series charge regulator. It is treated also the benefit of creating a circuit, with different methods, that can test the maximum power point trackers (MPPT for different photovoltaic applications.
CTE Corrections for WFPC2 and ACS
Dolphin, Andrew
2003-07-01
The error budget for optical broadband photometry is dominated by three factors: CTE corrections, long-short anomaly corrections, and photometric zero points. Questions about the dependencies of the CTE have largely been resolved, and my CTE corrections have been included in the WFPC2 handbook and tutorial. What remains to be done is the determination of the "final" CTE correction at the end of the WFPC2 mission, which will increase the accuracy of photometry obtained in the final few cycles. The long-short anomaly is still the subject of much debate, as it remains unclear whethere or not this effect is real and, if so, what its size and nature is. Photometric zero points have likewise varied by over 0.05 magnitudes in the literature, and will likely remain unresolved until the long-short anomaly is addressed {given that most calibration exposures are short while most science exposures are long}. It is also becoming apparent that similar issues will affect the accuracy of ACS photometry, and consequently that an ACS CTE study analogous to my WFPC2 work would significantly improve the calibration of ACS. I therefore propose to use archival WFPC2 images of omega Cen and ACS images of 47 Tuc to continue my HST calibration work. I also propose to begin work on "next-generation" CTE corrections, in which corrections are applied to the images based on accurate charge-trapping models rather than to the reduced photometry. This technique will allow for more accurate CTE corrections in certain cases {such as a star above a bright star or on a variable background}, improved PSF-fitting photometry of faint stars, and image restoration for accurate analysis of extended objects.
Real-Time Energy Management System for a Hybrid AC/DC Residential Microgrid
DEFF Research Database (Denmark)
Diaz, Enrique Rodriguez; Palacios-Garcia, Emilio J.; Anvari-Moghaddam, Amjad
2017-01-01
This paper proposes real-time Energy Management System (EMS) for a residential hybrid ac/dc microgrid. The residential microgrid is organized in two different distribution systems. A dc distribution bus which interconnect the renewable energy sources (RES), energy storage systems (ESS...... buildings. This architecture increases the overall efficiency of the distribution by interconnecting the RES and ESS thorough a dc distribution bus, and therefore avoiding unnecessary dc/ac conversion stages. The real-time EMS performs an 24 hours ahead optimization in order to schedule the charge...... setup. The results shown how the operational costs of the system are effectively decreased by 28%, even with non-accurate estimation of the RES generation or building parameters....
Diagrammatic methods in phase-space regularization
International Nuclear Information System (INIS)
Bern, Z.; Halpern, M.B.; California Univ., Berkeley
1987-11-01
Using the scalar prototype and gauge theory as the simplest possible examples, diagrammatic methods are developed for the recently proposed phase-space form of continuum regularization. A number of one-loop and all-order applications are given, including general diagrammatic discussions of the nogrowth theorem and the uniqueness of the phase-space stochastic calculus. The approach also generates an alternate derivation of the equivalence of the large-β phase-space regularization to the more conventional coordinate-space regularization. (orig.)
J-regular rings with injectivities
Shen, Liang
2010-01-01
A ring $R$ is called a J-regular ring if R/J(R) is von Neumann regular, where J(R) is the Jacobson radical of R. It is proved that if R is J-regular, then (i) R is right n-injective if and only if every homomorphism from an $n$-generated small right ideal of $R$ to $R_{R}$ can be extended to one from $R_{R}$ to $R_{R}$; (ii) R is right FP-injective if and only if R is right (J, R)-FP-injective. Some known results are improved.
Direct amplitude detuning measurement with ac dipole
Directory of Open Access Journals (Sweden)
S. White
2013-07-01
Full Text Available In circular machines, nonlinear dynamics can impact parameters such as beam lifetime and could result in limitations on the performance reach of the accelerator. Assessing and understanding these effects in experiments is essential to confirm the accuracy of the magnetic model and improve the machine performance. A direct measurement of the machine nonlinearities can be obtained by characterizing the dependency of the tune as a function of the amplitude of oscillations (usually defined as amplitude detuning. The conventional technique is to excite the beam to large amplitudes with a single kick and derive the tune from turn-by-turn data acquired with beam position monitors. Although this provides a very precise tune measurement it has the significant disadvantage of being destructive. An alternative, nondestructive way of exciting large amplitude oscillations is to use an ac dipole. The perturbation Hamiltonian in the presence of an ac dipole excitation shows a distinct behavior compared to the free oscillations which should be correctly taken into account in the interpretation of experimental data. The use of an ac dipole for direct amplitude detuning measurement requires careful data processing allowing one to observe the natural tune of the machine; the feasibility of such a measurement is demonstrated using experimental data from the Large Hadron Collider. An experimental proof of the theoretical derivations based on measurements performed at injection energy is provided as well as an application of this technique at top energy using a large number of excitations on the same beam.
Flame spread over inclined electrical wires with AC electric fields
Lim, Seung J.; Park, Sun H.; Park, Jeong; Fujita, Osamu; Keel, Sang I.; Chung, Suk-Ho
2017-01-01
Flame spread over polyethylene-insulated electrical wires was studied experimentally with applied alternating current (AC) by varying the inclination angle (θ), applied voltage (VAC), and frequency (fAC). For the baseline case with no electric field
EIT Imaging Regularization Based on Spectral Graph Wavelets.
Gong, Bo; Schullcke, Benjamin; Krueger-Ziolek, Sabine; Vauhkonen, Marko; Wolf, Gerhard; Mueller-Lisse, Ullrich; Moeller, Knut
2017-09-01
The objective of electrical impedance tomographic reconstruction is to identify the distribution of tissue conductivity from electrical boundary conditions. This is an ill-posed inverse problem usually solved under the finite-element method framework. In previous studies, standard sparse regularization was used for difference electrical impedance tomography to achieve a sparse solution. However, regarding elementwise sparsity, standard sparse regularization interferes with the smoothness of conductivity distribution between neighboring elements and is sensitive to noise. As an effect, the reconstructed images are spiky and depict a lack of smoothness. Such unexpected artifacts are not realistic and may lead to misinterpretation in clinical applications. To eliminate such artifacts, we present a novel sparse regularization method that uses spectral graph wavelet transforms. Single-scale or multiscale graph wavelet transforms are employed to introduce local smoothness on different scales into the reconstructed images. The proposed approach relies on viewing finite-element meshes as undirected graphs and applying wavelet transforms derived from spectral graph theory. Reconstruction results from simulations, a phantom experiment, and patient data suggest that our algorithm is more robust to noise and produces more reliable images.
International Nuclear Information System (INIS)
Gromov, K. Ya.; Gorozhankin, V.M.; Malov, L.A.; Fominykh, V.I.; Tsupko-Sitnikov, V.V.; Chumin, V.G.; Jakushev, E.A.; Kudrya, S.A.; Sergienko, V.A.; Malikov, Sh.R.
2004-01-01
Full text: Considerable attention has been given to nuclei with A = 220 - 230 recently. In this region there occurs transition from the spherical to the deformed nuclear shape, which gives rise to some specific features in the nuclear structure. In particular, negative parity levels with low excitation energies have been found in even-even nuclei from this region [1, 2]. One of the nuclei allowing experimental investigation of the above properties is 221 Fr. The nuclide 221 Fr is from the region of isotopes which does not include stable nuclei and thus it cannot be studied in several-nucleon transfer reactions. In addition, the neutron excess in this nucleus makes it impossible to study the nucleus in reactions with heavy ions. Experimental information on the 221 Fr level structure can only be gained from investigation of the 225 Ac (T 1/2 = 10 days) alpha decay or the 221 Rn (T 1/2 = 25 min) beta decay. In the latter case the possibilities of the investigation are restricted by difficulties in making of 221 Rn sources. Therefore, most information on the structure and properties of 221 Fr is derived from investigation of the 225 Ac α -decay [3]. In-depth investigation of ( α - γ )- coincidences at the 225 Ac decay is carried out. Twenty-one new weak γ - rays are found; 18 γ-rays earlier ascribed to the 225 Ac decay are not confirmed. The quantitative analysis of the ( α - γ )- coincidences makes it possible to find the intensity of 221 Fr levels by the decay and multipolarities of five weak γ -transitions. The conversion electron spectrum is investigated in the range of 5 † 24 keV with a high (some 20 eV) energy resolution. A new M1 type 10.6-keV γ-transition is found. The proposed 225 Ac decay scheme includes 31 excited 221 Fr states. Parities are established for 16 of them. Possible spin values are proposed for 221 Fr levels. Properties of excited 221 Fr states are satisfactorily described by the quasiparticle-phonon nuclear model without the
Vinay, K.; Shivakumar, K.; Ravikiran, Y. T.; Revanasiddappa, M.
2018-05-01
The present work is an investigation of ac conduction behaviour and dielectric response of Polyaniline/Ag/Graphene/SrTiO3 (PAGS) composite prepared by in-situ chemical oxidative interfacial polymerization using (NH4)2S2O8 as an oxidising agent at 0-5°C. The structural characterization of the samples was examined using FT-IR and XRD techniques. The ac conductivity and dielectric response of synthesized polymer composites were investigated at room temperature in the frequency range varying from 5 × 101 - 5 × 106 Hz using HIOKI make 3532-50 LCR Hi-tester. The ac conductivity increases with increase in frequency and follows the regular trend, the real dielectric constant (ɛ') and imaginary dielectric constant (ɛ'') decreases with increase in frequency and exhibits almost zero dielectric loss at higher frequencies, which suggests that the composite is a lossless material at frequencies beyond 3Hz.
Generalized regular genus for manifolds with boundary
Directory of Open Access Journals (Sweden)
Paola Cristofori
2003-05-01
Full Text Available We introduce a generalization of the regular genus, a combinatorial invariant of PL manifolds ([10], which is proved to be strictly related, in dimension three, to generalized Heegaard splittings defined in [12].
Geometric regularizations and dual conifold transitions
International Nuclear Information System (INIS)
Landsteiner, Karl; Lazaroiu, Calin I.
2003-01-01
We consider a geometric regularization for the class of conifold transitions relating D-brane systems on noncompact Calabi-Yau spaces to certain flux backgrounds. This regularization respects the SL(2,Z) invariance of the flux superpotential, and allows for computation of the relevant periods through the method of Picard-Fuchs equations. The regularized geometry is a noncompact Calabi-Yau which can be viewed as a monodromic fibration, with the nontrivial monodromy being induced by the regulator. It reduces to the original, non-monodromic background when the regulator is removed. Using this regularization, we discuss the simple case of the local conifold, and show how the relevant field-theoretic information can be extracted in this approach. (author)
Fast and compact regular expression matching
DEFF Research Database (Denmark)
Bille, Philip; Farach-Colton, Martin
2008-01-01
We study 4 problems in string matching, namely, regular expression matching, approximate regular expression matching, string edit distance, and subsequence indexing, on a standard word RAM model of computation that allows logarithmic-sized words to be manipulated in constant time. We show how...... to improve the space and/or remove a dependency on the alphabet size for each problem using either an improved tabulation technique of an existing algorithm or by combining known algorithms in a new way....
Regular-fat dairy and human health
DEFF Research Database (Denmark)
Astrup, Arne; Bradley, Beth H Rice; Brenna, J Thomas
2016-01-01
In recent history, some dietary recommendations have treated dairy fat as an unnecessary source of calories and saturated fat in the human diet. These assumptions, however, have recently been brought into question by current research on regular fat dairy products and human health. In an effort to......, cheese and yogurt, can be important components of an overall healthy dietary pattern. Systematic examination of the effects of dietary patterns that include regular-fat milk, cheese and yogurt on human health is warranted....
Deterministic automata for extended regular expressions
Directory of Open Access Journals (Sweden)
Syzdykov Mirzakhmet
2017-12-01
Full Text Available In this work we present the algorithms to produce deterministic finite automaton (DFA for extended operators in regular expressions like intersection, subtraction and complement. The method like “overriding” of the source NFA(NFA not defined with subset construction rules is used. The past work described only the algorithm for AND-operator (or intersection of regular languages; in this paper the construction for the MINUS-operator (and complement is shown.
Regularities of intermediate adsorption complex relaxation
International Nuclear Information System (INIS)
Manukova, L.A.
1982-01-01
The experimental data, characterizing the regularities of intermediate adsorption complex relaxation in the polycrystalline Mo-N 2 system at 77 K are given. The method of molecular beam has been used in the investigation. The analytical expressions of change regularity in the relaxation process of full and specific rates - of transition from intermediate state into ''non-reversible'', of desorption into the gas phase and accumUlation of the particles in the intermediate state are obtained
Online Manifold Regularization by Dual Ascending Procedure
Sun, Boliang; Li, Guohui; Jia, Li; Zhang, Hui
2013-01-01
We propose a novel online manifold regularization framework based on the notion of duality in constrained optimization. The Fenchel conjugate of hinge functions is a key to transfer manifold regularization from offline to online in this paper. Our algorithms are derived by gradient ascent in the dual function. For practical purpose, we propose two buffering strategies and two sparse approximations to reduce the computational complexity. Detailed experiments verify the utility of our approache...
Importance of Attenuation Correction (AC) for Small Animal PET Imaging
DEFF Research Database (Denmark)
El Ali, Henrik H.; Bodholdt, Rasmus Poul; Jørgensen, Jesper Tranekjær
2012-01-01
was performed. Methods: Ten NMRI nude mice with subcutaneous implantation of human breast cancer cells (MCF-7) were scanned consecutively in small animal PET and CT scanners (MicroPETTM Focus 120 and ImTek’s MicroCATTM II). CT-based AC, PET-based AC and uniform AC methods were compared. Results: The activity...
A new approach to nonlinear constrained Tikhonov regularization
Ito, Kazufumi
2011-09-16
We present a novel approach to nonlinear constrained Tikhonov regularization from the viewpoint of optimization theory. A second-order sufficient optimality condition is suggested as a nonlinearity condition to handle the nonlinearity of the forward operator. The approach is exploited to derive convergence rate results for a priori as well as a posteriori choice rules, e.g., discrepancy principle and balancing principle, for selecting the regularization parameter. The idea is further illustrated on a general class of parameter identification problems, for which (new) source and nonlinearity conditions are derived and the structural property of the nonlinearity term is revealed. A number of examples including identifying distributed parameters in elliptic differential equations are presented. © 2011 IOP Publishing Ltd.
High-resolution seismic data regularization and wavefield separation
Cao, Aimin; Stump, Brian; DeShon, Heather
2018-04-01
We present a new algorithm, non-equispaced fast antileakage Fourier transform (NFALFT), for irregularly sampled seismic data regularization. Synthetic tests from 1-D to 5-D show that the algorithm may efficiently remove leaked energy in the frequency wavenumber domain, and its corresponding regularization process is accurate and fast. Taking advantage of the NFALFT algorithm, we suggest a new method (wavefield separation) for the detection of the Earth's inner core shear wave with irregularly distributed seismic arrays or networks. All interfering seismic phases that propagate along the minor arc are removed from the time window around the PKJKP arrival. The NFALFT algorithm is developed for seismic data, but may also be used for other irregularly sampled temporal or spatial data processing.
Modelling and Control Design of a Dual Buck-Boost AC/DC Converter Used in the DC Nano-Grid
DEFF Research Database (Denmark)
Wu, Weimin; Liu, Yuan; Wang, Houqing
2016-01-01
Due to widely used DC characterized loads and more distributed power generation sources, the DC Nano-grid becomes more and more popular and seen as an alternative to the AC-grid in future. For the safety considerations, the DC Nano-grid should provide reliable grounding for the residential loads...... like the low voltage AC power system. In this paper, a dual Buck-Boost AC/DC converter for use in the united grounding configuration based DC Nano-grid with three terminal outputs is proposed. It will be much easy to construct an efficient DC Nano-grid based on the existing low AC power system by using...
Pixel-based CTE Correction of ACS/WFC: Modifications To The ACS Calibration Pipeline (CALACS)
Smith, Linda J.; Anderson, J.; Armstrong, A.; Avila, R.; Bedin, L.; Chiaberge, M.; Davis, M.; Ferguson, B.; Fruchter, A.; Golimowski, D.; Grogin, N.; Hack, W.; Lim, P. L.; Lucas, R.; Maybhate, A.; McMaster, M.; Ogaz, S.; Suchkov, A.; Ubeda, L.
2012-01-01
The Advanced Camera for Surveys (ACS) was installed on the Hubble Space Telescope (HST) nearly ten years ago. Over the last decade, continuous exposure to the harsh radiation environment has degraded the charge transfer efficiency (CTE) of the CCDs. The worsening CTE impacts the science that can be obtained by altering the photometric, astrometric and morphological characteristics of sources, particularly those farthest from the readout amplifiers. To ameliorate these effects, Anderson & Bedin (2010, PASP, 122, 1035) developed a pixel-based empirical approach to correcting ACS data by characterizing the CTE profiles of trails behind warm pixels in dark exposures. The success of this technique means that it is now possible to correct full-frame ACS/WFC images for CTE degradation in the standard data calibration and reduction pipeline CALACS. Over the past year, the ACS team at STScI has developed, refined and tested the new software. The details of this work are described in separate posters. The new code is more effective at low flux levels (repair ACS electronics) and pixel-based CTE correction. In addition to the standard cosmic ray corrected, flat-fielded and drizzled data products (crj, flt and drz files) there are three new equivalent files (crc, flc and drc) which contain the CTE-corrected data products. The user community will be able to choose whether to use the standard or CTE-corrected products.
HVDC transmission preferred to 750 kV ac
Energy Technology Data Exchange (ETDEWEB)
1965-06-25
It is unlikely that there will be a need in Britain for ac transmission voltages above 400 kV. But with the growing load density in the large conurbations with no possibility of local generation, high voltage dc transmission is likely to be most useful. It was concluded that by 1971 the 400 kV supergrid would be nation-wide and 6,200 circuit miles should be in service. With the expansion to accommodate the large new generating stations, the 400 kV supergrid would become an extremely high power distribution network rather than a transmission system. A higher voltage for transmission is outside the rational limit of speculation for a country the size of Britain.
An improved power control strategy for hybrid AC-DC microgrids
DEFF Research Database (Denmark)
Baharizadeh, Mehdi; Karshenas, Hamid Reza; Guerrero, Josep M.
2018-01-01
This paper presents a new droop-based control strategy for hybrid microgrids (HMG) with improved power sharing. When ac microgrids (AC-MG) and dc microgrids (DC-MG) are present in a distribution grid, there is an opportunity to interconnect them via an interlinking converter (IC) and form a HMG......, the possibility of participation of IC in AC-MG reactive power adds some complexity to a HMG control system. In this paper, a new decentralized control strategy is presented for a HMG which relies on regulating the voltage magnitude of a common bus in each microgrid. In this regard, new droop characteristics...... for sources across both microgrids as well as IC are proposed. The proposed droop characteristics result in better active/reactive power sharing across both microgrids and at the same time results in better voltage regulation. The derivation of new droop characteristics is thoroughly discussed in this paper...
Directory of Open Access Journals (Sweden)
Yang Liu
2008-01-01
Full Text Available Abstract The assembly of single-walled carbon nanotubes (SWCNTs using the AC dielectrophoresis technique is studied theoretically. It is found that the comb electrode bears better position control of SWCNTs compared to the parallel electrode. In the assembly, when some SWCNTs bridge the electrode first, they can greatly alter the local electrical field so as to “screen off” later coming SWCNTs, which contributes to the formation of dispersed SWCNT array. The screening distance scales with the gap width of electrodes and the length of SWCNTs, which provides a way to estimate the assembled density of SWCNTs. The influence of thermal noise on SWCNTs alignment is also analyzed in the simulation. It is shown that the status of the array distribution for SWCNTs is decided by the competition between the thermal noise and the AC electric-field strength. This influence of the thermal noise can be suppressed by using higher AC voltage to assemble the SWCNTs.
Directory of Open Access Journals (Sweden)
Rita de Cássia Félix Alvarez
2007-12-01
regulador de crescimento vegetal reduziu a altura das plantas e o acúmulo de 15N na panícula e promoveu a redistribuição do 15N absorvido e o aumento do 15N acumulado na raiz, colmo+bainha e folhas. A contribuição de 15N absorvido, em cada estádio estudado, para formação da panícula aumentou com o desenvolvimento das plantas, em menor proporção na presença do regulador de crescimento utilizado. O etil-trinexapac influenciou negativamente os componentes do rendimento e a massa de grãos de arroz.The high rice grain yields ensured by sprinkler irrigation have encouraged the use of higher fertilizer doses, mainly the nitrogen fertilizers. However, an improper management of nitrogen fertilization may result in plant lodging. Application of plant regulators may redirect assimilates to grain production while limiting the vegetative growth. This study aimed to: evaluate the influence of the growth regulator Ethyl-trinexapac on plant growth parameters and on 15N accumulation and distribution in the whole plant and plant components, and determine the contribution of nitrogen taken up in different developmental stages in panicle formation, yield components and rice yield. The experiment was carried out under controlled greenhouse conditions. The treatments consisted of application or not of a plant growth regulator (0 and 200 g active ingredient ha-1 of ethyl-trinexapac at four plant development stages (1 - beginning to end of tillering; 2 - end of tillering and flower differentiation; 3 - flower differentiation to flowering; 4 - flowering until physiological maturation. The experimental design was arranged in random blocks, in a 2 x 4 factorial scheme, with three replications. The plants were placed in a group of 48 pots. In a group of 24 pots with nutrient solution containing 15NH4SO4, plants were collected and separated in parts in the beginning of each pre-established plant development stage and at the end of each stage. In a second group (24 pots, pre-labeled plants
Improvements in GRACE Gravity Fields Using Regularization
Save, H.; Bettadpur, S.; Tapley, B. D.
2008-12-01
The unconstrained global gravity field models derived from GRACE are susceptible to systematic errors that show up as broad "stripes" aligned in a North-South direction on the global maps of mass flux. These errors are believed to be a consequence of both systematic and random errors in the data that are amplified by the nature of the gravity field inverse problem. These errors impede scientific exploitation of the GRACE data products, and limit the realizable spatial resolution of the GRACE global gravity fields in certain regions. We use regularization techniques to reduce these "stripe" errors in the gravity field products. The regularization criteria are designed such that there is no attenuation of the signal and that the solutions fit the observations as well as an unconstrained solution. We have used a computationally inexpensive method, normally referred to as "L-ribbon", to find the regularization parameter. This paper discusses the characteristics and statistics of a 5-year time-series of regularized gravity field solutions. The solutions show markedly reduced stripes, are of uniformly good quality over time, and leave little or no systematic observation residuals, which is a frequent consequence of signal suppression from regularization. Up to degree 14, the signal in regularized solution shows correlation greater than 0.8 with the un-regularized CSR Release-04 solutions. Signals from large-amplitude and small-spatial extent events - such as the Great Sumatra Andaman Earthquake of 2004 - are visible in the global solutions without using special post-facto error reduction techniques employed previously in the literature. Hydrological signals as small as 5 cm water-layer equivalent in the small river basins, like Indus and Nile for example, are clearly evident, in contrast to noisy estimates from RL04. The residual variability over the oceans relative to a seasonal fit is small except at higher latitudes, and is evident without the need for de-striping or
MATHEMATICAL MODELING OF AC ELECTRIC POINT MOTOR
Directory of Open Access Journals (Sweden)
S. YU. Buryak
2014-03-01
Full Text Available Purpose. In order to ensure reliability, security, and the most important the continuity of the transportation process, it is necessary to develop, implement, and then improve the automated methods of diagnostic mechanisms, devices and rail transport systems. Only systems that operate in real time mode and transmit data on the instantaneous state of the control objects can timely detect any faults and thus provide additional time for their correction by railway employees. Turnouts are one of the most important and responsible components, and therefore require the development and implementation of such diagnostics system.Methodology. Achieving the goal of monitoring and control of railway automation objects in real time is possible only with the use of an automated process of the objects state diagnosing. For this we need to know the diagnostic features of a control object, which determine its state at any given time. The most rational way of remote diagnostics is the shape and current spectrum analysis that flows in the power circuits of railway automatics. Turnouts include electric motors, which are powered by electric circuits, and the shape of the current curve depends on both the condition of the electric motor, and the conditions of the turnout maintenance. Findings. For the research and analysis of AC electric point motor it was developed its mathematical model. The calculation of parameters and interdependencies between the main factors affecting the operation of the asynchronous machine was conducted. The results of the model operation in the form of time dependences of the waveform curves of current on the load on engine shaft were obtained. Originality. During simulation the model of AC electric point motor, which satisfies the conditions of adequacy was built. Practical value. On the basis of the constructed model we can study the AC motor in various mode of operation, record and analyze current curve, as a response to various changes
AC susceptibility enhancement studies in magnetic systems
International Nuclear Information System (INIS)
Mukherjee, S.; Ranganathan, R.; Chakravarti, A.; Sil, S.
2001-01-01
Enhancement of AC susceptibility has been observed for typical ferromagnets (Gd), reentrant spin glasses like (Fe 1.5 Mn 1.5 Si) and canted spin systems (Ce(Fe 0.96 Al 0.04 ) 2 ). The data have been interpreted with the help of a simulation model based on dry friction-like pinning of domain walls for systems having ferromagnetic domain structures. A strong pinning mechanism appears in the reentrant spin glass like and canted spin systems at low temperatures in addition to the intrinsic one in the ferromagnetic phase. The temperature variation of the pinning potential has been given qualitatively for the reentrant spin glass like systems
Flexible AC transmission systems modelling and control
Zhang, Xiao-Ping; Pal, Bikash
2012-01-01
The extended and revised second edition of this successful monograph presents advanced modeling, analysis and control techniques of Flexible AC Transmission Systems (FACTS). The book covers comprehensively a range of power-system control problems: from steady-state voltage and power flow control, to voltage and reactive power control, to voltage stability control, to small signal stability control using FACTS controllers. In the six years since the first edition of the book has been published research on the FACTS has continued to flourish while renewable energy has developed into a mature and
Three-Level AC-DC-AC Z-Source Converter Using Reduced Passive Component Count
DEFF Research Database (Denmark)
Loh, Poh Chiang; Gao, Feng; Tan, Pee-Chin
2009-01-01
This paper presents a three-level ac-dc-ac Z-source converter with output voltage buck-boost capability. The converter is implemented by connecting a low-cost front-end diode rectifier to a neutral-point-clamped inverter through a single X-shaped LC impedance network. The inverter is controlled...... to switch with a three-level output voltage, where the middle neutral potential is uniquely tapped from the star-point of a wye-connected capacitive filter placed before the front-end diode rectifier for input current filtering. Through careful control, the resulting converter can produce the correct volt...
Transcranial Alternating Current Stimulation (tACS Mechanisms and Protocols
Directory of Open Access Journals (Sweden)
Amir V. Tavakoli
2017-09-01
Full Text Available Perception, cognition and consciousness can be modulated as a function of oscillating neural activity, while ongoing neuronal dynamics are influenced by synaptic activity and membrane potential. Consequently, transcranial alternating current stimulation (tACS may be used for neurological intervention. The advantageous features of tACS include the biphasic and sinusoidal tACS currents, the ability to entrain large neuronal populations, and subtle control over somatic effects. Through neuromodulation of phasic, neural activity, tACS is a powerful tool to investigate the neural correlates of cognition. The rapid development in this area requires clarity about best practices. Here we briefly introduce tACS and review the most compelling findings in the literature to provide a starting point for using tACS. We suggest that tACS protocols be based on functional brain mechanisms and appropriate control experiments, including active sham and condition blinding.
Forty Necessary and Sufficient Conditions for Regularity of Interval Matrices: A survey
Czech Academy of Sciences Publication Activity Database
Rohn, Jiří
2009-01-01
Roč. 18, - (2009), s. 500-512 E-ISSN 1081-3810 R&D Projects: GA ČR GA201/09/1957; GA ČR GC201/08/J020 Institutional research plan: CEZ:AV0Z10300504 Keywords : interval matrix * regularity * singularity * necessary and sufficient condition * algorithm Subject RIV: BA - General Mathematics Impact factor: 0.892, year: 2009 http://www.math.technion.ac.il/iic/ ela / ela -articles/articles/vol18_pp500-512.pdf
Regular Expression Matching and Operational Semantics
Directory of Open Access Journals (Sweden)
Asiri Rathnayake
2011-08-01
Full Text Available Many programming languages and tools, ranging from grep to the Java String library, contain regular expression matchers. Rather than first translating a regular expression into a deterministic finite automaton, such implementations typically match the regular expression on the fly. Thus they can be seen as virtual machines interpreting the regular expression much as if it were a program with some non-deterministic constructs such as the Kleene star. We formalize this implementation technique for regular expression matching using operational semantics. Specifically, we derive a series of abstract machines, moving from the abstract definition of matching to increasingly realistic machines. First a continuation is added to the operational semantics to describe what remains to be matched after the current expression. Next, we represent the expression as a data structure using pointers, which enables redundant searches to be eliminated via testing for pointer equality. From there, we arrive both at Thompson's lockstep construction and a machine that performs some operations in parallel, suitable for implementation on a large number of cores, such as a GPU. We formalize the parallel machine using process algebra and report some preliminary experiments with an implementation on a graphics processor using CUDA.
Regularities, Natural Patterns and Laws of Nature
Directory of Open Access Journals (Sweden)
Stathis Psillos
2014-02-01
Full Text Available The goal of this paper is to sketch an empiricist metaphysics of laws of nature. The key idea is that there are regularities without regularity-enforcers. Differently put, there are natural laws without law-makers of a distinct metaphysical kind. This sketch will rely on the concept of a natural pattern and more significantly on the existence of a network of natural patterns in nature. The relation between a regularity and a pattern will be analysed in terms of mereology. Here is the road map. In section 2, I will briefly discuss the relation between empiricism and metaphysics, aiming to show that an empiricist metaphysics is possible. In section 3, I will offer arguments against stronger metaphysical views of laws. Then, in section 4 I will motivate nomic objectivism. In section 5, I will address the question ‘what is a regularity?’ and will develop a novel answer to it, based on the notion of a natural pattern. In section 6, I will raise the question: ‘what is a law of nature?’, the answer to which will be: a law of nature is a regularity that is characterised by the unity of a natural pattern.
Bifurcation theory of ac electric arcing
International Nuclear Information System (INIS)
Christen, Thomas; Peinke, Emanuel
2012-01-01
The performance of alternating current (ac) electric arcing devices is related to arc extinction or its re-ignition at zero crossings of the current (so-called ‘current zero’, CZ). Theoretical investigations thus usually focus on the transient behaviour of arcs near CZ, e.g. by solving the modelling differential equations in the vicinity of CZ. This paper proposes as an alternative approach to investigate global mathematical properties of the underlying periodically driven dynamic system describing the electric circuit containing the arcing device. For instance, the uniqueness of the trivial solution associated with the insulating state indicates the extinction of any arc. The existence of non-trivial attractors (typically a time-periodic state) points to a re-ignition of certain arcs. The performance regions of arcing devices, such as circuit breakers and arc torches, can thus be identified with the regions of absence and existence, respectively, of non-trivial attractors. Most important for applications, the boundary of a performance region in the model parameter space is then associated with the bifurcation of the non-trivial attractors. The concept is illustrated for simple black-box arc models, such as the Mayr and the Cassie model, by calculating for various cases the performance boundaries associated with the bifurcation of ac arcs. (paper)
A nonlinear model for AC induced corrosion
Directory of Open Access Journals (Sweden)
N. Ida
2012-09-01
Full Text Available The modeling of corrosion poses particular difficulties. The understanding of corrosion as an electrochemical process has led to simple capacitive-resistive models that take into account the resistance of the electrolytic cell and the capacitive effect of the surface potential at the interface between conductors and the electrolyte. In some models nonlinear conduction effects have been added to account for more complex observed behavior. While these models are sufficient to describe the behavior in systems with cathodic protection, the behavior in the presence of induced AC currents from power lines and from RF sources cannot be accounted for and are insufficient to describe the effects observed in the field. Field observations have shown that a rectifying effect exists that affects the cathodic protection potential and this effect is responsible for corrosion in the presence of AC currents. The rectifying effects of the metal-corrosion interface are totally missing from current models. This work proposes a nonlinear model based on finite element analysis that takes into account the nonlinear behavior of the metal-oxide interface and promises to improve modeling by including the rectification effects at the interface.
Measuring Gravitational Flexion in ACS Clusters
Goldberg, David
2005-07-01
We propose measurement of the gravitational "Flexion" signal in ACS cluster images. The flexion, or "arciness" of a lensed background galaxy arises from variations in the lensing field. As a result, it is extremely sensitive to small scale perturbations in the field, and thus, to substructure in clusters. Moreover, because flexion represents gravitationally induced asymmetries in the lensed image, it is completely separable from traditional measurements of shear, which focus on the induced ellipticity of the image, and thus, the two signals may be extracted simultaneously. Since typical galaxies are roughly symmetric upon 180 degree rotation, even a small induced flexion can potentially produce a noticeable effect {Goldberg & Bacon, 2005}. We propose the measurement of substructure within approximately 4 clusters with high-quality ACS data, and will further apply a test of a new tomographic technique whereby comparisons of lensed arcs at different redshifts may be used to estimate the background cosmology, and thus place constraints on the equation of state of dark energy.
Fractional Regularization Term for Variational Image Registration
Directory of Open Access Journals (Sweden)
Rafael Verdú-Monedero
2009-01-01
Full Text Available Image registration is a widely used task of image analysis with applications in many fields. Its classical formulation and current improvements are given in the spatial domain. In this paper a regularization term based on fractional order derivatives is formulated. This term is defined and implemented in the frequency domain by translating the energy functional into the frequency domain and obtaining the Euler-Lagrange equations which minimize it. The new regularization term leads to a simple formulation and design, being applicable to higher dimensions by using the corresponding multidimensional Fourier transform. The proposed regularization term allows for a real gradual transition from a diffusion registration to a curvature registration which is best suited to some applications and it is not possible in the spatial domain. Results with 3D actual images show the validity of this approach.
International Nuclear Information System (INIS)
Obregon, Octavio; Quevedo, Hernando; Ryan, Michael P.
2004-01-01
We construct a family of time and angular dependent, regular S-brane solutions which corresponds to a simple analytical continuation of the Zipoy-Voorhees 4-dimensional vacuum spacetime. The solutions are asymptotically flat and turn out to be free of singularities without requiring a twist in space. They can be considered as the simplest non-singular generalization of the singular S0-brane solution. We analyze the properties of a representative of this family of solutions and show that it resembles to some extent the asymptotic properties of the regular Kerr S-brane. The R-symmetry corresponds, however, to the general lorentzian symmetry. Several generalizations of this regular solution are derived which include a charged S-brane and an additional dilatonic field. (author)
Online Manifold Regularization by Dual Ascending Procedure
Directory of Open Access Journals (Sweden)
Boliang Sun
2013-01-01
Full Text Available We propose a novel online manifold regularization framework based on the notion of duality in constrained optimization. The Fenchel conjugate of hinge functions is a key to transfer manifold regularization from offline to online in this paper. Our algorithms are derived by gradient ascent in the dual function. For practical purpose, we propose two buffering strategies and two sparse approximations to reduce the computational complexity. Detailed experiments verify the utility of our approaches. An important conclusion is that our online MR algorithms can handle the settings where the target hypothesis is not fixed but drifts with the sequence of examples. We also recap and draw connections to earlier works. This paper paves a way to the design and analysis of online manifold regularization algorithms.
DEFF Research Database (Denmark)
Borregaard, Michael Krabbe; Hendrichsen, Ditte Katrine; Nachman, Gøsta Støger
2008-01-01
, depending on the nature of intraspecific interactions between them: while the individuals of some species repel each other and partition the available area, others form groups of varying size, determined by the fitness of each group member. The spatial distribution pattern of individuals again strongly......Living organisms are distributed over the entire surface of the planet. The distribution of the individuals of each species is not random; on the contrary, they are strongly dependent on the biology and ecology of the species, and vary over different spatial scale. The structure of whole...... populations reflects the location and fragmentation pattern of the habitat types preferred by the species, and the complex dynamics of migration, colonization, and population growth taking place over the landscape. Within these, individuals are distributed among each other in regular or clumped patterns...
Deletion of the AcMNPV core gene ac109 results in budded virions that are non-infectious
International Nuclear Information System (INIS)
Fang Minggang; Nie, Yingchao; Theilmann, David A.
2009-01-01
Autographa californica multiple nucleopolyhedrovirus (AcMNPV) ac109 is a core gene and its function in the virus life cycle is unknown. To determine its role in the baculovirus life cycle, we used the AcMNPV bacmid system to generate an ac109 deletion virus (vAc 109KO ). Fluorescence and light microscopy showed that transfection of vAc 109KO results in a single-cell infection phenotype. Viral DNA replication is unaffected and the development of occlusion bodies in vAc 109KO -transfected cells evidenced progression to the very late phases of viral infection. Western blot and confocal immunofluorescence analysis showed that AC109 is expressed in the cytoplasm and nucleus throughout infection. In addition, AC109 is a structural protein as it was detected in both budded virus (BV) and occlusion derived virus in both the envelope and nucleocapsid fractions. Titration assays by qPCR and TCID 50 showed that vAc 109KO produced BV but the virions are non-infectious. The vAc 109KO BV were indistinguishable from the BV of repaired and wild type control viruses as determined by negative staining and electron microscopy.
SAR image regularization with fast approximate discrete minimization.
Denis, Loïc; Tupin, Florence; Darbon, Jérôme; Sigelle, Marc
2009-07-01
Synthetic aperture radar (SAR) images, like other coherent imaging modalities, suffer from speckle noise. The presence of this noise makes the automatic interpretation of images a challenging task and noise reduction is often a prerequisite for successful use of classical image processing algorithms. Numerous approaches have been proposed to filter speckle noise. Markov random field (MRF) modelization provides a convenient way to express both data fidelity constraints and desirable properties of the filtered image. In this context, total variation minimization has been extensively used to constrain the oscillations in the regularized image while preserving its edges. Speckle noise follows heavy-tailed distributions, and the MRF formulation leads to a minimization problem involving nonconvex log-likelihood terms. Such a minimization can be performed efficiently by computing minimum cuts on weighted graphs. Due to memory constraints, exact minimization, although theoretically possible, is not achievable on large images required by remote sensing applications. The computational burden of the state-of-the-art algorithm for approximate minimization (namely the alpha -expansion) is too heavy specially when considering joint regularization of several images. We show that a satisfying solution can be reached, in few iterations, by performing a graph-cut-based combinatorial exploration of large trial moves. This algorithm is applied to joint regularization of the amplitude and interferometric phase in urban area SAR images.
Modeling and reliability analysis of three phase z-source AC-AC converter
Directory of Open Access Journals (Sweden)
Prasad Hanuman
2017-12-01
Full Text Available This paper presents the small signal modeling using the state space averaging technique and reliability analysis of a three-phase z-source ac-ac converter. By controlling the shoot-through duty ratio, it can operate in buck-boost mode and maintain desired output voltage during voltage sag and surge condition. It has faster dynamic response and higher efficiency as compared to the traditional voltage regulator. Small signal analysis derives different control transfer functions and this leads to design a suitable controller for a closed loop system during supply voltage variation. The closed loop system of the converter with a PID controller eliminates the transients in output voltage and provides steady state regulated output. The proposed model designed in the RT-LAB and executed in a field programming gate array (FPGA-based real-time digital simulator at a fixedtime step of 10 μs and a constant switching frequency of 10 kHz. The simulator was developed using very high speed integrated circuit hardware description language (VHDL, making it versatile and moveable. Hardware-in-the-loop (HIL simulation results are presented to justify the MATLAB simulation results during supply voltage variation of the three phase z-source ac-ac converter. The reliability analysis has been applied to the converter to find out the failure rate of its different components.
Regular transport dynamics produce chaotic travel times.
Villalobos, Jorge; Muñoz, Víctor; Rogan, José; Zarama, Roberto; Johnson, Neil F; Toledo, Benjamín; Valdivia, Juan Alejandro
2014-06-01
In the hope of making passenger travel times shorter and more reliable, many cities are introducing dedicated bus lanes (e.g., Bogota, London, Miami). Here we show that chaotic travel times are actually a natural consequence of individual bus function, and hence of public transport systems more generally, i.e., chaotic dynamics emerge even when the route is empty and straight, stops and lights are equidistant and regular, and loading times are negligible. More generally, our findings provide a novel example of chaotic dynamics emerging from a single object following Newton's laws of motion in a regularized one-dimensional system.
Regularity of difference equations on Banach spaces
Agarwal, Ravi P; Lizama, Carlos
2014-01-01
This work introduces readers to the topic of maximal regularity for difference equations. The authors systematically present the method of maximal regularity, outlining basic linear difference equations along with relevant results. They address recent advances in the field, as well as basic semigroup and cosine operator theories in the discrete setting. The authors also identify some open problems that readers may wish to take up for further research. This book is intended for graduate students and researchers in the area of difference equations, particularly those with advance knowledge of and interest in functional analysis.
PET regularization by envelope guided conjugate gradients
International Nuclear Information System (INIS)
Kaufman, L.; Neumaier, A.
1996-01-01
The authors propose a new way to iteratively solve large scale ill-posed problems and in particular the image reconstruction problem in positron emission tomography by exploiting the relation between Tikhonov regularization and multiobjective optimization to obtain iteratively approximations to the Tikhonov L-curve and its corner. Monitoring the change of the approximate L-curves allows us to adjust the regularization parameter adaptively during a preconditioned conjugate gradient iteration, so that the desired solution can be reconstructed with a small number of iterations
Matrix regularization of embedded 4-manifolds
International Nuclear Information System (INIS)
Trzetrzelewski, Maciej
2012-01-01
We consider products of two 2-manifolds such as S 2 ×S 2 , embedded in Euclidean space and show that the corresponding 4-volume preserving diffeomorphism algebra can be approximated by a tensor product SU(N)⊗SU(N) i.e. functions on a manifold are approximated by the Kronecker product of two SU(N) matrices. A regularization of the 4-sphere is also performed by constructing N 2 ×N 2 matrix representations of the 4-algebra (and as a byproduct of the 3-algebra which makes the regularization of S 3 also possible).
Schrabback, T.; Erben, T.; Simon, P.; Miralles, J.-M.; Schneider, P.; Heymans, C.; Eifler, T.; Fosbury, R. A. E.; Freudling, W.; Hetterscheidt, M.; Hildebrandt, H.; Pirzkal, N.
2007-06-01
Context: This is the first paper of a series describing our measurement of weak lensing by large-scale structure, also termed “cosmic shear”, using archival observations from the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST). Aims: In this work we present results from a pilot study testing the capabilities of the ACS for cosmic shear measurements with early parallel observations and presenting a re-analysis of HST/ACS data from the GEMS survey and the GOODS observations of the Chandra Deep Field South (CDFS). Methods: We describe the data reduction and, in particular, a new correction scheme for the time-dependent ACS point-spread-function (PSF) based on observations of stellar fields. This is currently the only technique which takes the full time variation of the PSF between individual ACS exposures into account. We estimate that our PSF correction scheme reduces the systematic contribution to the shear correlation functions due to PSF distortions to MUSIC sample, we determine a local single field estimate for the mass power spectrum normalisation σ8, CDFS=0.52+0.11-0.15 (stat) ± 0.07(sys) (68% confidence assuming Gaussian cosmic variance) at a fixed matter density Ω_m=0.3 for a ΛCDM cosmology marginalising over the uncertainty of the Hubble parameter and the redshift distribution. We interpret this exceptionally low estimate to be due to a local under-density of the foreground structures in the CDFS. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archives at the Space Telescope European Coordinating Facility and the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
Endpoint singularities in unintegrated parton distributions
Hautmann, F
2007-01-01
We examine the singular behavior from the endpoint region x -> 1 in parton distributions unintegrated in both longitudinal and transverse momenta. We identify and regularize the singularities by using the subtraction method, and compare this with the cut-off regularization method. The counterterms for the distributions with subtractive regularization are given in coordinate space by compact all-order expressions in terms of eikonal-line operators. We carry out an explicit calculation at one loop for the unintegrated quark distribution. We discuss the relation of the unintegrated parton distributions in subtractive regularization with the ordinary parton distributions.
Formation factor of regular porous pattern in poly-α-methylstyrene film
International Nuclear Information System (INIS)
Yang Ruizhuang; Xu Jiajing; Gao Cong; Ma Shuang; Chen Sufen; Luo Xuan; Fang Yu; Li Bo
2015-01-01
Regular poly-α-methylstyrene (PAMS) porous film with macron-sized cells was prepared by casting the solution in the condition with high humidity. In this paper, the effects of the molecular weight of PAMS, PAMS concentration, humidity, temperature, volatile solvents and the thickness of liquid of solution on formation of regular porous pattern in PAMS film were discussed. The results show that these factors significantly affect the pore size and the pore distribution. The capillary force and Benard-Marangoni convection are main driving forces for the water droplet moving and making pores regular arrangement. (authors)
On a correspondence between regular and non-regular operator monotone functions
DEFF Research Database (Denmark)
Gibilisco, P.; Hansen, Frank; Isola, T.
2009-01-01
We prove the existence of a bijection between the regular and the non-regular operator monotone functions satisfying a certain functional equation. As an application we give a new proof of the operator monotonicity of certain functions related to the Wigner-Yanase-Dyson skew information....
Preference mapping of lemon lime carbonated beverages with regular and diet beverage consumers.
Leksrisompong, P P; Lopetcharat, K; Guthrie, B; Drake, M A
2013-02-01
The drivers of liking of lemon-lime carbonated beverages were investigated with regular and diet beverage consumers. Ten beverages were selected from a category survey of commercial beverages using a D-optimal procedure. Beverages were subjected to consumer testing (n = 101 regular beverage consumers, n = 100 diet beverage consumers). Segmentation of consumers was performed on overall liking scores followed by external preference mapping of selected samples. Diet beverage consumers liked 2 diet beverages more than regular beverage consumers. There were no differences in the overall liking scores between diet and regular beverage consumers for other products except for a sparkling beverage sweetened with juice which was more liked by regular beverage consumers. Three subtle but distinct consumer preference clusters were identified. Two segments had evenly distributed diet and regular beverage consumers but one segment had a greater percentage of regular beverage consumers (P beverage consumers) did not have a large impact on carbonated beverage liking. Instead, mouthfeel attributes were major drivers of liking when these beverages were tested in a blind tasting. Preference mapping of lemon-lime carbonated beverage with diet and regular beverage consumers allowed the determination of drivers of liking of both populations. The understanding of how mouthfeel attributes, aromatics, and basic tastes impact liking or disliking of products was achieved. Preference drivers established in this study provide product developers of carbonated lemon-lime beverages with additional information to develop beverages that may be suitable for different groups of consumers. © 2013 Institute of Food Technologists®
Regularity and irreversibility of weekly travel behavior
Kitamura, R.; van der Hoorn, A.I.J.M.
1987-01-01
Dynamic characteristics of travel behavior are analyzed in this paper using weekly travel diaries from two waves of panel surveys conducted six months apart. An analysis of activity engagement indicates the presence of significant regularity in weekly activity participation between the two waves.
Regular and context-free nominal traces
DEFF Research Database (Denmark)
Degano, Pierpaolo; Ferrari, Gian-Luigi; Mezzetti, Gianluca
2017-01-01
Two kinds of automata are presented, for recognising new classes of regular and context-free nominal languages. We compare their expressive power with analogous proposals in the literature, showing that they express novel classes of languages. Although many properties of classical languages hold ...
Faster 2-regular information-set decoding
Bernstein, D.J.; Lange, T.; Peters, C.P.; Schwabe, P.; Chee, Y.M.
2011-01-01
Fix positive integers B and w. Let C be a linear code over F 2 of length Bw. The 2-regular-decoding problem is to find a nonzero codeword consisting of w length-B blocks, each of which has Hamming weight 0 or 2. This problem appears in attacks on the FSB (fast syndrome-based) hash function and
Complexity in union-free regular languages
Czech Academy of Sciences Publication Activity Database
Jirásková, G.; Masopust, Tomáš
2011-01-01
Roč. 22, č. 7 (2011), s. 1639-1653 ISSN 0129-0541 Institutional research plan: CEZ:AV0Z10190503 Keywords : Union-free regular language * one-cycle-free-path automaton * descriptional complexity Subject RIV: BA - General Mathematics Impact factor: 0.379, year: 2011 http://www.worldscinet.com/ijfcs/22/2207/S0129054111008933.html
Regular Gleason Measures and Generalized Effect Algebras
Dvurečenskij, Anatolij; Janda, Jiří
2015-12-01
We study measures, finitely additive measures, regular measures, and σ-additive measures that can attain even infinite values on the quantum logic of a Hilbert space. We show when particular classes of non-negative measures can be studied in the frame of generalized effect algebras.
Regularization of finite temperature string theories
International Nuclear Information System (INIS)
Leblanc, Y.; Knecht, M.; Wallet, J.C.
1990-01-01
The tachyonic divergences occurring in the free energy of various string theories at finite temperature are eliminated through the use of regularization schemes and analytic continuations. For closed strings, we obtain finite expressions which, however, develop an imaginary part above the Hagedorn temperature, whereas open string theories are still plagued with dilatonic divergences. (orig.)
A Sim(2 invariant dimensional regularization
Directory of Open Access Journals (Sweden)
J. Alfaro
2017-09-01
Full Text Available We introduce a Sim(2 invariant dimensional regularization of loop integrals. Then we can compute the one loop quantum corrections to the photon self energy, electron self energy and vertex in the Electrodynamics sector of the Very Special Relativity Standard Model (VSRSM.
Continuum regularized Yang-Mills theory
International Nuclear Information System (INIS)
Sadun, L.A.
1987-01-01
Using the machinery of stochastic quantization, Z. Bern, M. B. Halpern, C. Taubes and I recently proposed a continuum regularization technique for quantum field theory. This regularization may be implemented by applying a regulator to either the (d + 1)-dimensional Parisi-Wu Langevin equation or, equivalently, to the d-dimensional second order Schwinger-Dyson (SD) equations. This technique is non-perturbative, respects all gauge and Lorentz symmetries, and is consistent with a ghost-free gauge fixing (Zwanziger's). This thesis is a detailed study of this regulator, and of regularized Yang-Mills theory, using both perturbative and non-perturbative techniques. The perturbative analysis comes first. The mechanism of stochastic quantization is reviewed, and a perturbative expansion based on second-order SD equations is developed. A diagrammatic method (SD diagrams) for evaluating terms of this expansion is developed. We apply the continuum regulator to a scalar field theory. Using SD diagrams, we show that all Green functions can be rendered finite to all orders in perturbation theory. Even non-renormalizable theories can be regularized. The continuum regulator is then applied to Yang-Mills theory, in conjunction with Zwanziger's gauge fixing. A perturbative expansion of the regulator is incorporated into the diagrammatic method. It is hoped that the techniques discussed in this thesis will contribute to the construction of a renormalized Yang-Mills theory is 3 and 4 dimensions
Gravitational lensing by a regular black hole
International Nuclear Information System (INIS)
Eiroa, Ernesto F; Sendra, Carlos M
2011-01-01
In this paper, we study a regular Bardeen black hole as a gravitational lens. We find the strong deflection limit for the deflection angle, from which we obtain the positions and magnifications of the relativistic images. As an example, we apply the results to the particular case of the supermassive black hole at the center of our galaxy.
Gravitational lensing by a regular black hole
Energy Technology Data Exchange (ETDEWEB)
Eiroa, Ernesto F; Sendra, Carlos M, E-mail: eiroa@iafe.uba.ar, E-mail: cmsendra@iafe.uba.ar [Instituto de Astronomia y Fisica del Espacio, CC 67, Suc. 28, 1428, Buenos Aires (Argentina)
2011-04-21
In this paper, we study a regular Bardeen black hole as a gravitational lens. We find the strong deflection limit for the deflection angle, from which we obtain the positions and magnifications of the relativistic images. As an example, we apply the results to the particular case of the supermassive black hole at the center of our galaxy.
Analytic stochastic regularization and gange invariance
International Nuclear Information System (INIS)
Abdalla, E.; Gomes, M.; Lima-Santos, A.
1986-05-01
A proof that analytic stochastic regularization breaks gauge invariance is presented. This is done by an explicit one loop calculation of the vaccum polarization tensor in scalar electrodynamics, which turns out not to be transversal. The counterterm structure, Langevin equations and the construction of composite operators in the general framework of stochastic quantization, are also analysed. (Author) [pt
Stabilization, pole placement, and regular implementability
Belur, MN; Trentelman, HL
In this paper, we study control by interconnection of linear differential systems. We give necessary and sufficient conditions for regular implementability of a-given linear, differential system. We formulate the problems of stabilization and pole placement as problems of finding a suitable,
12 CFR 725.3 - Regular membership.
2010-01-01
... UNION ADMINISTRATION CENTRAL LIQUIDITY FACILITY § 725.3 Regular membership. (a) A natural person credit....5(b) of this part, and forwarding with its completed application funds equal to one-half of this... 1, 1979, is not required to forward these funds to the Facility until October 1, 1979. (3...
Supervised scale-regularized linear convolutionary filters
DEFF Research Database (Denmark)
Loog, Marco; Lauze, Francois Bernard
2017-01-01
also be solved relatively efficient. All in all, the idea is to properly control the scale of a trained filter, which we solve by introducing a specific regularization term into the overall objective function. We demonstrate, on an artificial filter learning problem, the capabil- ities of our basic...
On regular riesz operators | Raubenheimer | Quaestiones ...
African Journals Online (AJOL)
The r-asymptotically quasi finite rank operators on Banach lattices are examples of regular Riesz operators. We characterise Riesz elements in a subalgebra of a Banach algebra in terms of Riesz elements in the Banach algebra. This enables us to characterise r-asymptotically quasi finite rank operators in terms of adjoint ...
Regularized Discriminant Analysis: A Large Dimensional Study
Yang, Xiaoke
2018-04-28
In this thesis, we focus on studying the performance of general regularized discriminant analysis (RDA) classifiers. The data used for analysis is assumed to follow Gaussian mixture model with different means and covariances. RDA offers a rich class of regularization options, covering as special cases the regularized linear discriminant analysis (RLDA) and the regularized quadratic discriminant analysis (RQDA) classi ers. We analyze RDA under the double asymptotic regime where the data dimension and the training size both increase in a proportional way. This double asymptotic regime allows for application of fundamental results from random matrix theory. Under the double asymptotic regime and some mild assumptions, we show that the asymptotic classification error converges to a deterministic quantity that only depends on the data statistical parameters and dimensions. This result not only implicates some mathematical relations between the misclassification error and the class statistics, but also can be leveraged to select the optimal parameters that minimize the classification error, thus yielding the optimal classifier. Validation results on the synthetic data show a good accuracy of our theoretical findings. We also construct a general consistent estimator to approximate the true classification error in consideration of the unknown previous statistics. We benchmark the performance of our proposed consistent estimator against classical estimator on synthetic data. The observations demonstrate that the general estimator outperforms others in terms of mean squared error (MSE).
Complexity in union-free regular languages
Czech Academy of Sciences Publication Activity Database
Jirásková, G.; Masopust, Tomáš
2011-01-01
Roč. 22, č. 7 (2011), s. 1639-1653 ISSN 0129-0541 Institutional research plan: CEZ:AV0Z10190503 Keywords : Union-free regular language * one-cycle-free- path automaton * descriptional complexity Subject RIV: BA - General Mathematics Impact factor: 0.379, year: 2011 http://www.worldscinet.com/ijfcs/22/2207/S0129054111008933.html
Bit-coded regular expression parsing
DEFF Research Database (Denmark)
Nielsen, Lasse; Henglein, Fritz
2011-01-01
the DFA-based parsing algorithm due to Dub ´e and Feeley to emit the bits of the bit representation without explicitly materializing the parse tree itself. We furthermore show that Frisch and Cardelli’s greedy regular expression parsing algorithm can be straightforwardly modified to produce bit codings...
Tetravalent one-regular graphs of order 4p2
DEFF Research Database (Denmark)
Feng, Yan-Quan; Kutnar, Klavdija; Marusic, Dragan
2014-01-01
A graph is one-regular if its automorphism group acts regularly on the set of its arcs. In this paper tetravalent one-regular graphs of order 4p2, where p is a prime, are classified.......A graph is one-regular if its automorphism group acts regularly on the set of its arcs. In this paper tetravalent one-regular graphs of order 4p2, where p is a prime, are classified....
AC losses in high Tc superconductors
International Nuclear Information System (INIS)
Campbell, A.M.
1998-01-01
Full text: Although in principle the AC losses in high Tc superconductors can be calculated from the critical current density, a number of complications make this difficult. The Jc is very field dependent, there are intergranular and intragranular critical currents, the material is anisotropic and there is usually a large demagnetising factor. Care must be taken in interpreting electrical measurements since the voltage depends on the position of the contacts. In spite of these complications the simple theory of Norris has proved surprisingly successful and arguments will be presented as to why this is the case. Results on a range of tapes will be compared with theory and numerical methods for predicting losses discussed. Finally a theory for coupling losses will be given for a composite conductor with high resistance barriers round the filaments
Transcranial alternating current stimulation (tACS
Directory of Open Access Journals (Sweden)
Andrea eAntal
2013-06-01
Full Text Available Transcranial alternating current stimulation (tACS seems likely to open a new era of the field of noninvasive electrical stimulation of the human brain by directly interfering with cortical rhythms. It is expected to synchronize (by one single resonance frequency or desynchronize (e.g. by the application of several frequencies cortical oscillations. If applied long enough it may cause neuroplastic effects. In the theta range it may improve cognition when applied in phase. Alpha rhythms could improve motor performance, whereas beta intrusion may deteriorate them. TACS with both alpha and beta frequencies has a high likelihood to induce retinal phosphenes. Gamma intrusion can possibly interfere with attention. Stimulation in the ripple range induces intensity dependent inhibition or excitation in the motor cortex most likely by entrainment of neuronal networks, whereas stimulation in the low kHz range induces excitation by neuronal membrane interference. TACS in the 200 kHz range may have a potential in oncology.
Ac loss measurement of SSC dipole magnets
International Nuclear Information System (INIS)
Delchamps, S.; Hanft, R.; Jaffery, T.; Kinney, W.; Koska, W.; Lamm, M.J.; Mazur, P.O.; Orris, D.; Ozelis, J.P.; Strait, J.; Wake, M.
1992-09-01
AC losses in full length and 1.5 m model SSC collider dipoles were successfully measured by the direct observation of energy flow into and out of magnets during a ramp cycle. The measurement was performed by using two double-integrating type digital volt meters (DVM's) for current and voltage measurement. Measurements were performed for six is m long ASST magnets and five 1.5 m long model magnets, inducting one 40 mm diameter magnet. There were large variations in the eddy current losses. Since these magnets use conductors with slight deviations in their internal structures and processing of the copper surface depending on the manufacturer, it is likely that there are differences in the contact resistance between strands. Correlation between the ramp rate dependence of the,quench current and the eddy current loss was evident
Huang, Zhengxing; Dong, Wei; Duan, Huilong; Liu, Jiquan
2018-05-01
Acute coronary syndrome (ACS), as a common and severe cardiovascular disease, is a leading cause of death and the principal cause of serious long-term disability globally. Clinical risk prediction of ACS is important for early intervention and treatment. Existing ACS risk scoring models are based mainly on a small set of hand-picked risk factors and often dichotomize predictive variables to simplify the score calculation. This study develops a regularized stacked denoising autoencoder (SDAE) model to stratify clinical risks of ACS patients from a large volume of electronic health records (EHR). To capture characteristics of patients at similar risk levels, and preserve the discriminating information across different risk levels, two constraints are added on SDAE to make the reconstructed feature representations contain more risk information of patients, which contribute to a better clinical risk prediction result. We validate our approach on a real clinical dataset consisting of 3464 ACS patient samples. The performance of our approach for predicting ACS risk remains robust and reaches 0.868 and 0.73 in terms of both AUC and accuracy, respectively. The obtained results show that the proposed approach achieves a competitive performance compared to state-of-the-art models in dealing with the clinical risk prediction problem. In addition, our approach can extract informative risk factors of ACS via a reconstructive learning strategy. Some of these extracted risk factors are not only consistent with existing medical domain knowledge, but also contain suggestive hypotheses that could be validated by further investigations in the medical domain.
Ac irreversibility line of bismuth-based high temperature superconductors
Energy Technology Data Exchange (ETDEWEB)
Mehdaoui, A. [Laboratoire de Physique et de Spectroscopie Electronique, URA 1435 Faculte des Sciences, Universite de Haute Alsace 4, rue des Freres Lumiere, 68093 Mulhouse Cedex (France); Beille, J. [Laboratoire Louis Neel, CNRS, BP 166, 38042 Grenoble Cedex 9 (France); Berling, D.; Loegel, B. [Laboratoire de Physique et de Spectroscopie Electronique, URA 1435 Faculte des Sciences, Universite de Haute Alsace 4, rue des Freres Lumiere, 68093 Mulhouse Cedex (France); Noudem, J.G.; Tournier, R. [EPM-MATFORMAG, Laboratoire dElaboration par Procede Magnetique, CNRS, BP 166, 38042 Grenoble Cedex 9 (France)
1997-09-01
We discuss the magnetic properties of lead doped Bi-2223 bulk samples obtained through combined magnetic melt texturing and hot pressing (MMTHP). The ac complex susceptibility measurements are achieved over a broad ac field range (1 Oe{lt}h{sub ac}{lt}100 Oe) and show highly anisotropic properties. The intergranular coupling is improved in the direction perpendicular to the applied stress and magnetic field direction, and an intragranular loss peak is observed for the first time. A comparison is made with other bismuth-based compounds and it is shown that the MMTHP process shifts the ac irreversibility line (ac IL) toward higher fields. It is also shown that all the ac IL{close_quote}s for quasi 2D bismuth-based compounds show a nearly quadratic temperature dependence and deviate therefore strongly from the linear behavior observed in quasi 3D compounds and expected from a critical state model.{copyright} {ital 1997 Materials Research Society.}
Ac irreversibility line of bismuth-based high temperature superconductors
International Nuclear Information System (INIS)
Mehdaoui, A.; Beille, J.; Berling, D.; Loegel, B.; Noudem, J.G.; Tournier, R.
1997-01-01
We discuss the magnetic properties of lead doped Bi-2223 bulk samples obtained through combined magnetic melt texturing and hot pressing (MMTHP). The ac complex susceptibility measurements are achieved over a broad ac field range (1 Oe ac <100 Oe) and show highly anisotropic properties. The intergranular coupling is improved in the direction perpendicular to the applied stress and magnetic field direction, and an intragranular loss peak is observed for the first time. A comparison is made with other bismuth-based compounds and it is shown that the MMTHP process shifts the ac irreversibility line (ac IL) toward higher fields. It is also shown that all the ac IL close-quote s for quasi 2D bismuth-based compounds show a nearly quadratic temperature dependence and deviate therefore strongly from the linear behavior observed in quasi 3D compounds and expected from a critical state model.copyright 1997 Materials Research Society
AC conductivity and dielectric behavior of bulk Furfurylidenemalononitrile
El-Nahass, M. M.; Ali, H. A. M.
2012-06-01
AC conductivity and dielectric behavior for bulk Furfurylidenemalononitrile have been studied over a temperature range (293-333 K) and frequency range (50-5×106 Hz). The frequency dependence of ac conductivity, σac, has been investigated by the universal power law, σac(ω)=Aωs. The variation of the frequency exponent (s) with temperature was analyzed in terms of different conduction mechanisms, and it was found that the correlated barrier hopping (CBH) model is the predominant conduction mechanism. The temperature dependence of σac(ω) showed a linear increase with the increase in temperature at different frequencies. The ac activation energy was determined at different frequencies. Dielectric data were analyzed using complex permittivity and complex electric modulus for bulk Furfurylidenemalononitrile at various temperatures.
Quantification of fetal heart rate regularity using symbolic dynamics
van Leeuwen, P.; Cysarz, D.; Lange, S.; Geue, D.; Groenemeyer, D.
2007-03-01
Fetal heart rate complexity was examined on the basis of RR interval time series obtained in the second and third trimester of pregnancy. In each fetal RR interval time series, short term beat-to-beat heart rate changes were coded in 8bit binary sequences. Redundancies of the 28 different binary patterns were reduced by two different procedures. The complexity of these sequences was quantified using the approximate entropy (ApEn), resulting in discrete ApEn values which were used for classifying the sequences into 17 pattern sets. Also, the sequences were grouped into 20 pattern classes with respect to identity after rotation or inversion of the binary value. There was a specific, nonuniform distribution of the sequences in the pattern sets and this differed from the distribution found in surrogate data. In the course of gestation, the number of sequences increased in seven pattern sets, decreased in four and remained unchanged in six. Sequences that occurred less often over time, both regular and irregular, were characterized by patterns reflecting frequent beat-to-beat reversals in heart rate. They were also predominant in the surrogate data, suggesting that these patterns are associated with stochastic heart beat trains. Sequences that occurred more frequently over time were relatively rare in the surrogate data. Some of these sequences had a high degree of regularity and corresponded to prolonged heart rate accelerations or decelerations which may be associated with directed fetal activity or movement or baroreflex activity. Application of the pattern classes revealed that those sequences with a high degree of irregularity correspond to heart rate patterns resulting from complex physiological activity such as fetal breathing movements. The results suggest that the development of the autonomic nervous system and the emergence of fetal behavioral states lead to increases in not only irregular but also regular heart rate patterns. Using symbolic dynamics to
Magnetic irreversibility in granular superconductors: ac susceptibility study
International Nuclear Information System (INIS)
Perez, F.; Obradors, X.; Fontcuberta, J.; Vallet, M.; Gonzalez-Calbet, J.
1991-01-01
Ac susceptibility measurements of a ceramic weak-coupled superconductor in very low ac fields (2mG, 111Hz) are reported. We present evidence for the observation of the magnetic irreversibility following a ZFC-FC thermal cycling by means of ac susceptibilty measurements. It is shown that this technique also reflect local magnetic field effects in granular superconductors, as previously suggested in microwave surface resistance and I-V characteristics. (orig.)
Statistical regularities in the rank-citation profile of scientists.
Petersen, Alexander M; Stanley, H Eugene; Succi, Sauro
2011-01-01
Recent science of science research shows that scientific impact measures for journals and individual articles have quantifiable regularities across both time and discipline. However, little is known about the scientific impact distribution at the scale of an individual scientist. We analyze the aggregate production and impact using the rank-citation profile c(i)(r) of 200 distinguished professors and 100 assistant professors. For the entire range of paper rank r, we fit each c(i)(r) to a common distribution function. Since two scientists with equivalent Hirsch h-index can have significantly different c(i)(r) profiles, our results demonstrate the utility of the β(i) scaling parameter in conjunction with h(i) for quantifying individual publication impact. We show that the total number of citations C(i) tallied from a scientist's N(i) papers scales as [Formula: see text]. Such statistical regularities in the input-output patterns of scientists can be used as benchmarks for theoretical models of career progress.
AC Own Motion Percentage of Randomly Sampled Cases
Social Security Administration — Longitudinal report detailing the numbers and percentages of Appeals Council (AC) own motion review actions taken on un-appealed favorable hearing level decisions...
AC electric motors control advanced design techniques and applications
Giri, Fouad
2013-01-01
The complexity of AC motor control lies in the multivariable and nonlinear nature of AC machine dynamics. Recent advancements in control theory now make it possible to deal with long-standing problems in AC motors control. This text expertly draws on these developments to apply a wide range of model-based control designmethods to a variety of AC motors. Contributions from over thirty top researchers explain how modern control design methods can be used to achieve tight speed regulation, optimal energetic efficiency, and operation reliability and safety, by considering online state var
Wind-powered asynchronous AC/DC/AC converter system. [for electric power supply regulation
Reitan, D. K.
1973-01-01
Two asynchronous ac/dc/ac systems are modelled that utilize wind power to drive a variable or constant hertz alternator. The first system employs a high power 60-hertz inverter tie to the large backup supply of the power company to either supplement them from wind energy, storage, or from a combination of both at a preset desired current; rectifier and inverter are identical and operate in either mode depending on the silicon control rectifier firing angle. The second system employs the same rectification but from a 60-hertz alternator arrangement; it provides mainly dc output, some sinusoidal 60-hertz from the wind bus and some high harmonic content 60-hertz from an 800-watt inverter.
Stability Analysis for Isolated AC Microgrids Based on PV-Active Generators
DEFF Research Database (Denmark)
Aldana, Nelson Leonardo Diaz; Coelho, Ernane A. A.; Quintero, Juan Carlos Vasquez
2015-01-01
The current trend in isolated microgrids is oriented to distributed renewable energy generators, such as photovoltaic (PV) generators and their corresponding distributed energy storage systems (ESS) as an unit denoted as active generator (PV+ESS). In an isolated microgrid, every distributed...... for all the distributed generators. In particular, ESS’s based on batteries require at least two different mode of charge. As consequence, the topological operation mode of the microgrid is affected by the changes of the operation mode of each distributed generator. Typically, droop control loops are used...... for interconnecting several different distributed generators in parallel to a common bus, whose parameters determine the stability and damping of the microgrid operation. In this paper, a small-signal stability analysis is applied to an isolated AC microgrid composed of (PV+ESS) active generators, regarding three...
Save, H.; Bettadpur, S. V.
2013-12-01
It has been demonstrated before that using Tikhonov regularization produces spherical harmonic solutions from GRACE that have very little residual stripes while capturing all the signal observed by GRACE within the noise level. This paper demonstrates a two-step process and uses Tikhonov regularization to remove the residual stripes in the CSR regularized spherical harmonic coefficients when computing the spatial projections. We discuss methods to produce mass anomaly grids that have no stripe features while satisfying the necessary condition of capturing all observed signal within the GRACE noise level.
Directory of Open Access Journals (Sweden)
Patrick W. Keeley
2014-10-01
Full Text Available Retinal neurons are often arranged as non-random distributions called mosaics, as their somata minimize proximity to neighboring cells of the same type. The horizontal cells serve as an example of such a mosaic, but little is known about the developmental mechanisms that underlie their patterning. To identify genes involved in this process, we have used three different spatial statistics to assess the patterning of the horizontal cell mosaic across a panel of genetically distinct recombinant inbred strains. To avoid the confounding effect cell density, which varies two-fold across these different strains, we computed the real/random regularity ratio, expressing the regularity of a mosaic relative to a randomly distributed simulation of similarly sized cells. To test whether this latter statistic better reflects the variation in biological processes that contribute to horizontal cell spacing, we subsequently compared the genetic linkage for each of these two traits, the regularity index and the real/random regularity ratio, each computed from the distribution of nearest neighbor (NN distances and from the Voronoi domain (VD areas. Finally, we compared each of these analyses with another index of patterning, the packing factor. Variation in the regularity indexes, as well as their real/random regularity ratios, and the packing factor, mapped quantitative trait loci (QTL to the distal ends of Chromosomes 1 and 14. For the NN and VD analyses, we found that the degree of linkage was greater when using the real/random regularity ratio rather than the respective regularity index. Using informatic resources, we narrow the list of prospective genes positioned at these two intervals to a small collection of six genes that warrant further investigation to determine their potential role in shaping the patterning of the horizontal cell mosaic.
Stream Processing Using Grammars and Regular Expressions
DEFF Research Database (Denmark)
Rasmussen, Ulrik Terp
disambiguation. The first algorithm operates in two passes in a semi-streaming fashion, using a constant amount of working memory and an auxiliary tape storage which is written in the first pass and consumed by the second. The second algorithm is a single-pass and optimally streaming algorithm which outputs...... as much of the parse tree as is semantically possible based on the input prefix read so far, and resorts to buffering as many symbols as is required to resolve the next choice. Optimality is obtained by performing a PSPACE-complete pre-analysis on the regular expression. In the second part we present...... Kleenex, a language for expressing high-performance streaming string processing programs as regular grammars with embedded semantic actions, and its compilation to streaming string transducers with worst-case linear-time performance. Its underlying theory is based on transducer decomposition into oracle...
Describing chaotic attractors: Regular and perpetual points
Dudkowski, Dawid; Prasad, Awadhesh; Kapitaniak, Tomasz
2018-03-01
We study the concepts of regular and perpetual points for describing the behavior of chaotic attractors in dynamical systems. The idea of these points, which have been recently introduced to theoretical investigations, is thoroughly discussed and extended into new types of models. We analyze the correlation between regular and perpetual points, as well as their relation with phase space, showing the potential usefulness of both types of points in the qualitative description of co-existing states. The ability of perpetual points in finding attractors is indicated, along with its potential cause. The location of chaotic trajectories and sets of considered points is investigated and the study on the stability of systems is shown. The statistical analysis of the observing desired states is performed. We focus on various types of dynamical systems, i.e., chaotic flows with self-excited and hidden attractors, forced mechanical models, and semiconductor superlattices, exhibiting the universality of appearance of the observed patterns and relations.
Chaos regularization of quantum tunneling rates
International Nuclear Information System (INIS)
Pecora, Louis M.; Wu Dongho; Lee, Hoshik; Antonsen, Thomas; Lee, Ming-Jer; Ott, Edward
2011-01-01
Quantum tunneling rates through a barrier separating two-dimensional, symmetric, double-well potentials are shown to depend on the classical dynamics of the billiard trajectories in each well and, hence, on the shape of the wells. For shapes that lead to regular (integrable) classical dynamics the tunneling rates fluctuate greatly with eigenenergies of the states sometimes by over two orders of magnitude. Contrarily, shapes that lead to completely chaotic trajectories lead to tunneling rates whose fluctuations are greatly reduced, a phenomenon we call regularization of tunneling rates. We show that a random-plane-wave theory of tunneling accounts for the mean tunneling rates and the small fluctuation variances for the chaotic systems.
Least square regularized regression in sum space.
Xu, Yong-Li; Chen, Di-Rong; Li, Han-Xiong; Liu, Lu
2013-04-01
This paper proposes a least square regularized regression algorithm in sum space of reproducing kernel Hilbert spaces (RKHSs) for nonflat function approximation, and obtains the solution of the algorithm by solving a system of linear equations. This algorithm can approximate the low- and high-frequency component of the target function with large and small scale kernels, respectively. The convergence and learning rate are analyzed. We measure the complexity of the sum space by its covering number and demonstrate that the covering number can be bounded by the product of the covering numbers of basic RKHSs. For sum space of RKHSs with Gaussian kernels, by choosing appropriate parameters, we tradeoff the sample error and regularization error, and obtain a polynomial learning rate, which is better than that in any single RKHS. The utility of this method is illustrated with two simulated data sets and five real-life databases.
Contour Propagation With Riemannian Elasticity Regularization
DEFF Research Database (Denmark)
Bjerre, Troels; Hansen, Mads Fogtmann; Sapru, W.
2011-01-01
Purpose/Objective(s): Adaptive techniques allow for correction of spatial changes during the time course of the fractionated radiotherapy. Spatial changes include tumor shrinkage and weight loss, causing tissue deformation and residual positional errors even after translational and rotational image...... the planning CT onto the rescans and correcting to reflect actual anatomical changes. For deformable registration, a free-form, multi-level, B-spline deformation model with Riemannian elasticity, penalizing non-rigid local deformations, and volumetric changes, was used. Regularization parameters was defined...... on the original delineation and tissue deformation in the time course between scans form a better starting point than rigid propagation. There was no significant difference of locally and globally defined regularization. The method used in the present study suggests that deformed contours need to be reviewed...
Thin accretion disk around regular black hole
Directory of Open Access Journals (Sweden)
QIU Tianqi
2014-08-01
Full Text Available The Penrose′s cosmic censorship conjecture says that naked singularities do not exist in nature.So,it seems reasonable to further conjecture that not even a singularity exists in nature.In this paper,a regular black hole without singularity is studied in detail,especially on its thin accretion disk,energy flux,radiation temperature and accretion efficiency.It is found that the interaction of regular black hole is stronger than that of the Schwarzschild black hole. Furthermore,the thin accretion will be more efficiency to lost energy while the mass of black hole decreased. These particular properties may be used to distinguish between black holes.
Convex nonnegative matrix factorization with manifold regularization.
Hu, Wenjun; Choi, Kup-Sze; Wang, Peiliang; Jiang, Yunliang; Wang, Shitong
2015-03-01
Nonnegative Matrix Factorization (NMF) has been extensively applied in many areas, including computer vision, pattern recognition, text mining, and signal processing. However, nonnegative entries are usually required for the data matrix in NMF, which limits its application. Besides, while the basis and encoding vectors obtained by NMF can represent the original data in low dimension, the representations do not always reflect the intrinsic geometric structure embedded in the data. Motivated by manifold learning and Convex NMF (CNMF), we propose a novel matrix factorization method called Graph Regularized and Convex Nonnegative Matrix Factorization (GCNMF) by introducing a graph regularized term into CNMF. The proposed matrix factorization technique not only inherits the intrinsic low-dimensional manifold structure, but also allows the processing of mixed-sign data matrix. Clustering experiments on nonnegative and mixed-sign real-world data sets are conducted to demonstrate the effectiveness of the proposed method. Copyright © 2014 Elsevier Ltd. All rights reserved.
A short proof of increased parabolic regularity
Directory of Open Access Journals (Sweden)
Stephen Pankavich
2015-08-01
Full Text Available We present a short proof of the increased regularity obtained by solutions to uniformly parabolic partial differential equations. Though this setting is fairly introductory, our new method of proof, which uses a priori estimates and an inductive method, can be extended to prove analogous results for problems with time-dependent coefficients, advection-diffusion or reaction diffusion equations, and nonlinear PDEs even when other tools, such as semigroup methods or the use of explicit fundamental solutions, are unavailable.
Regular black hole in three dimensions
Myung, Yun Soo; Yoon, Myungseok
2008-01-01
We find a new black hole in three dimensional anti-de Sitter space by introducing an anisotropic perfect fluid inspired by the noncommutative black hole. This is a regular black hole with two horizons. We compare thermodynamics of this black hole with that of non-rotating BTZ black hole. The first-law of thermodynamics is not compatible with the Bekenstein-Hawking entropy.
Sparse regularization for force identification using dictionaries
Qiao, Baijie; Zhang, Xingwu; Wang, Chenxi; Zhang, Hang; Chen, Xuefeng
2016-04-01
The classical function expansion method based on minimizing l2-norm of the response residual employs various basis functions to represent the unknown force. Its difficulty lies in determining the optimum number of basis functions. Considering the sparsity of force in the time domain or in other basis space, we develop a general sparse regularization method based on minimizing l1-norm of the coefficient vector of basis functions. The number of basis functions is adaptively determined by minimizing the number of nonzero components in the coefficient vector during the sparse regularization process. First, according to the profile of the unknown force, the dictionary composed of basis functions is determined. Second, a sparsity convex optimization model for force identification is constructed. Third, given the transfer function and the operational response, Sparse reconstruction by separable approximation (SpaRSA) is developed to solve the sparse regularization problem of force identification. Finally, experiments including identification of impact and harmonic forces are conducted on a cantilever thin plate structure to illustrate the effectiveness and applicability of SpaRSA. Besides the Dirac dictionary, other three sparse dictionaries including Db6 wavelets, Sym4 wavelets and cubic B-spline functions can also accurately identify both the single and double impact forces from highly noisy responses in a sparse representation frame. The discrete cosine functions can also successfully reconstruct the harmonic forces including the sinusoidal, square and triangular forces. Conversely, the traditional Tikhonov regularization method with the L-curve criterion fails to identify both the impact and harmonic forces in these cases.
Analytic stochastic regularization and gauge theories
International Nuclear Information System (INIS)
Abdalla, E.; Gomes, M.; Lima-Santos, A.
1987-04-01
We prove that analytic stochatic regularization braks gauge invariance. This is done by an explicit one loop calculation of the two three and four point vertex functions of the gluon field in scalar chromodynamics, which turns out not to be geuge invariant. We analyse the counter term structure, Langevin equations and the construction of composite operators in the general framework of stochastic quantization. (author) [pt
Preconditioners for regularized saddle point matrices
Czech Academy of Sciences Publication Activity Database
Axelsson, Owe
2011-01-01
Roč. 19, č. 2 (2011), s. 91-112 ISSN 1570-2820 Institutional research plan: CEZ:AV0Z30860518 Keywords : saddle point matrices * preconditioning * regularization * eigenvalue clustering Subject RIV: BA - General Mathematics Impact factor: 0.533, year: 2011 http://www.degruyter.com/view/j/jnma.2011.19.issue-2/jnum.2011.005/jnum.2011.005. xml
Analytic stochastic regularization: gauge and supersymmetry theories
International Nuclear Information System (INIS)
Abdalla, M.C.B.
1988-01-01
Analytic stochastic regularization for gauge and supersymmetric theories is considered. Gauge invariance in spinor and scalar QCD is verified to brak fown by an explicit one loop computation of the two, theree and four point vertex function of the gluon field. As a result, non gauge invariant counterterms must be added. However, in the supersymmetric multiplets there is a cancellation rendering the counterterms gauge invariant. The calculation is considered at one loop order. (author) [pt
Regularized forecasting of chaotic dynamical systems
International Nuclear Information System (INIS)
Bollt, Erik M.
2017-01-01
While local models of dynamical systems have been highly successful in terms of using extensive data sets observing even a chaotic dynamical system to produce useful forecasts, there is a typical problem as follows. Specifically, with k-near neighbors, kNN method, local observations occur due to recurrences in a chaotic system, and this allows for local models to be built by regression to low dimensional polynomial approximations of the underlying system estimating a Taylor series. This has been a popular approach, particularly in context of scalar data observations which have been represented by time-delay embedding methods. However such local models can generally allow for spatial discontinuities of forecasts when considered globally, meaning jumps in predictions because the collected near neighbors vary from point to point. The source of these discontinuities is generally that the set of near neighbors varies discontinuously with respect to the position of the sample point, and so therefore does the model built from the near neighbors. It is possible to utilize local information inferred from near neighbors as usual but at the same time to impose a degree of regularity on a global scale. We present here a new global perspective extending the general local modeling concept. In so doing, then we proceed to show how this perspective allows us to impose prior presumed regularity into the model, by involving the Tikhonov regularity theory, since this classic perspective of optimization in ill-posed problems naturally balances fitting an objective with some prior assumed form of the result, such as continuity or derivative regularity for example. This all reduces to matrix manipulations which we demonstrate on a simple data set, with the implication that it may find much broader context.
Minimal length uncertainty relation and ultraviolet regularization
Kempf, Achim; Mangano, Gianpiero
1997-06-01
Studies in string theory and quantum gravity suggest the existence of a finite lower limit Δx0 to the possible resolution of distances, at the latest on the scale of the Planck length of 10-35 m. Within the framework of the Euclidean path integral we explicitly show ultraviolet regularization in field theory through this short distance structure. Both rotation and translation invariance can be preserved. An example is studied in detail.
Ac conductivity and dielectric properties of bulk tin phthalocyanine dichloride (SnPcCl 2)
El-Nahass, M. M.; Farid, A. M.; Abd El-Rahman, K. F.; Ali, H. A. M.
2008-07-01
The ac conductivity, σac( ω), has been measured for bulk tin phthalocyanine dichloride (SnPcCl 2) in the form of compressed pellet with evaporated ohmic Au electrodes in a temperature range 303-403 K. Ac conductivity, σac( ω), is found to vary as ωs in the frequency range 42 Hz-5×10 6 Hz. At low range of frequency, s<1 and it decreases with the increase in temperature indicating a dominant hopping process. At high range of frequency, s is found to be equal to ≈1.09 and is temperature independent. The dielectric constant, ε1, and dialectic loss, ε2, have been determined for bulk SnPcCl 2. Both ε1 and ε2 decrease with the increase in frequency and increase with the increase in temperature. The Cole-Cole types have been used to determine some parameters such as; the macroscopic relaxation time ( τo), the molecular relaxation time ( τ), the activation energy for relaxation ( Eo) and the distribution parameter ( α). The temperature dependence of τ is expressed by a thermally activated process with the activation energy of 0.299 eV.
Regularity and chaos in cavity QED
International Nuclear Information System (INIS)
Bastarrachea-Magnani, Miguel Angel; López-del-Carpio, Baldemar; Chávez-Carlos, Jorge; Lerma-Hernández, Sergio; Hirsch, Jorge G
2017-01-01
The interaction of a quantized electromagnetic field in a cavity with a set of two-level atoms inside it can be described with algebraic Hamiltonians of increasing complexity, from the Rabi to the Dicke models. Their algebraic character allows, through the use of coherent states, a semiclassical description in phase space, where the non-integrable Dicke model has regions associated with regular and chaotic motion. The appearance of classical chaos can be quantified calculating the largest Lyapunov exponent over the whole available phase space for a given energy. In the quantum regime, employing efficient diagonalization techniques, we are able to perform a detailed quantitative study of the regular and chaotic regions, where the quantum participation ratio (P R ) of coherent states on the eigenenergy basis plays a role equivalent to the Lyapunov exponent. It is noted that, in the thermodynamic limit, dividing the participation ratio by the number of atoms leads to a positive value in chaotic regions, while it tends to zero in the regular ones. (paper)
Solution path for manifold regularized semisupervised classification.
Wang, Gang; Wang, Fei; Chen, Tao; Yeung, Dit-Yan; Lochovsky, Frederick H
2012-04-01
Traditional learning algorithms use only labeled data for training. However, labeled examples are often difficult or time consuming to obtain since they require substantial human labeling efforts. On the other hand, unlabeled data are often relatively easy to collect. Semisupervised learning addresses this problem by using large quantities of unlabeled data with labeled data to build better learning algorithms. In this paper, we use the manifold regularization approach to formulate the semisupervised learning problem where a regularization framework which balances a tradeoff between loss and penalty is established. We investigate different implementations of the loss function and identify the methods which have the least computational expense. The regularization hyperparameter, which determines the balance between loss and penalty, is crucial to model selection. Accordingly, we derive an algorithm that can fit the entire path of solutions for every value of the hyperparameter. Its computational complexity after preprocessing is quadratic only in the number of labeled examples rather than the total number of labeled and unlabeled examples.
Regularizations: different recipes for identical situations
International Nuclear Information System (INIS)
Gambin, E.; Lobo, C.O.; Battistel, O.A.
2004-03-01
We present a discussion where the choice of the regularization procedure and the routing for the internal lines momenta are put at the same level of arbitrariness in the analysis of Ward identities involving simple and well-known problems in QFT. They are the complex self-interacting scalar field and two simple models where the SVV and AVV process are pertinent. We show that, in all these problems, the conditions to symmetry relations preservation are put in terms of the same combination of divergent Feynman integrals, which are evaluated in the context of a very general calculational strategy, concerning the manipulations and calculations involving divergences. Within the adopted strategy, all the arbitrariness intrinsic to the problem are still maintained in the final results and, consequently, a perfect map can be obtained with the corresponding results of the traditional regularization techniques. We show that, when we require an universal interpretation for the arbitrariness involved, in order to get consistency with all stated physical constraints, a strong condition is imposed for regularizations which automatically eliminates the ambiguities associated to the routing of the internal lines momenta of loops. The conclusion is clean and sound: the association between ambiguities and unavoidable symmetry violations in Ward identities cannot be maintained if an unique recipe is required for identical situations in the evaluation of divergent physical amplitudes. (author)
Mutation Glu82Lys in lamin A/C gene is associated with cardiomyopathy and conduction defect
International Nuclear Information System (INIS)
Wang Hu; Wang Jizheng; Zheng Weiyue; Wang Xiaojian; Wang Shuxia; Song Lei; Zou Yubao; Yao Yan; Hui Rutai
2006-01-01
Dilated cardiomyopathy is a form of heart muscle disease characterized by impaired systolic function and ventricular dilation. The mutations in lamin A/C gene have been linked to dilated cardiomyopathy. We screened genetic mutations in a large Chinese family of 50 members including members with dilated cardiomyopathy and found a Glu82Lys substitution mutation in the rod domain of the lamin A/C protein in eight family members, three of them have been diagnosed as dilated cardiomyopathy, one presented with heart dilation. The pathogenic mechanism of lamin A/C gene defect is poorly understood. Glu82Lys mutated lamin A/C and wild type protein was transfected into HEK293 cells. The mutated protein was not properly localized at the inner nuclear membrane and the emerin protein, which interacts with lamin A/C, was also aberrantly distributed. The nuclear membrane structure was disrupted and heterochromatin was aggregated aberrantly in the nucleus of the HEK293 cells stably transfected with mutated lamin A/C gene as determined by transmission electron microscopy
Energy Technology Data Exchange (ETDEWEB)
Hong, Z; Jiang, Y; Pei, R; Coombs, T A [Electronic, Power and Energy Conversion Group, Engineering Department, University of Cambridge, CB2 1PZ (United Kingdom); Ye, L [Department of Electrical Power Engineering, CAU, P. O. Box 210, Beijing 100083 (China); Campbell, A M [Interdisciplinary Research Centre in Superconductivity, University of Cambridge, CB3 0HE (United Kingdom)], E-mail: Zh223@cam.ac.uk
2008-02-15
In order to utilize HTS conductors in AC electrical devices, it is very important to be able to understand the characteristics of HTS materials in the AC electromagnetic conditions and give an accurate estimate of the AC loss. A numerical method is proposed in this paper to estimate the AC loss in superconducting conductors including MgB{sub 2} wires and YBCO coated conductors. This method is based on solving a set of partial differential equations in which the magnetic field is used as the state variable to get the current and electric field distributions in the cross sections of the conductors and hence the AC loss can be calculated. This method is used to model a single-element and a multi-element MgB{sub 2} wires. The results demonstrate that the multi-element MgB{sub 2} wire has a lower AC loss than a single-element one when carrying the same current. The model is also used to simulate YBCO coated conductors by simplifying the superconducting thin tape into a one-dimensional region where the thickness of the coated conductor can be ignored. The results show a good agreement with the measurement.
Parekh, Ankit
Sparsity has become the basis of some important signal processing methods over the last ten years. Many signal processing problems (e.g., denoising, deconvolution, non-linear component analysis) can be expressed as inverse problems. Sparsity is invoked through the formulation of an inverse problem with suitably designed regularization terms. The regularization terms alone encode sparsity into the problem formulation. Often, the ℓ1 norm is used to induce sparsity, so much so that ℓ1 regularization is considered to be `modern least-squares'. The use of ℓ1 norm, as a sparsity-inducing regularizer, leads to a convex optimization problem, which has several benefits: the absence of extraneous local minima, well developed theory of globally convergent algorithms, even for large-scale problems. Convex regularization via the ℓ1 norm, however, tends to under-estimate the non-zero values of sparse signals. In order to estimate the non-zero values more accurately, non-convex regularization is often favored over convex regularization. However, non-convex regularization generally leads to non-convex optimization, which suffers from numerous issues: convergence may be guaranteed to only a stationary point, problem specific parameters may be difficult to set, and the solution is sensitive to the initialization of the algorithm. The first part of this thesis is aimed toward combining the benefits of non-convex regularization and convex optimization to estimate sparse signals more effectively. To this end, we propose to use parameterized non-convex regularizers with designated non-convexity and provide a range for the non-convex parameter so as to ensure that the objective function is strictly convex. By ensuring convexity of the objective function (sum of data-fidelity and non-convex regularizer), we can make use of a wide variety of convex optimization algorithms to obtain the unique global minimum reliably. The second part of this thesis proposes a non-linear signal
Sparsity regularization for parameter identification problems
International Nuclear Information System (INIS)
Jin, Bangti; Maass, Peter
2012-01-01
The investigation of regularization schemes with sparsity promoting penalty terms has been one of the dominant topics in the field of inverse problems over the last years, and Tikhonov functionals with ℓ p -penalty terms for 1 ⩽ p ⩽ 2 have been studied extensively. The first investigations focused on regularization properties of the minimizers of such functionals with linear operators and on iteration schemes for approximating the minimizers. These results were quickly transferred to nonlinear operator equations, including nonsmooth operators and more general function space settings. The latest results on regularization properties additionally assume a sparse representation of the true solution as well as generalized source conditions, which yield some surprising and optimal convergence rates. The regularization theory with ℓ p sparsity constraints is relatively complete in this setting; see the first part of this review. In contrast, the development of efficient numerical schemes for approximating minimizers of Tikhonov functionals with sparsity constraints for nonlinear operators is still ongoing. The basic iterated soft shrinkage approach has been extended in several directions and semi-smooth Newton methods are becoming applicable in this field. In particular, the extension to more general non-convex, non-differentiable functionals by variational principles leads to a variety of generalized iteration schemes. We focus on such iteration schemes in the second part of this review. A major part of this survey is devoted to applying sparsity constrained regularization techniques to parameter identification problems for partial differential equations, which we regard as the prototypical setting for nonlinear inverse problems. Parameter identification problems exhibit different levels of complexity and we aim at characterizing a hierarchy of such problems. The operator defining these inverse problems is the parameter-to-state mapping. We first summarize some
Ac and dc motor flooding times
International Nuclear Information System (INIS)
Crowley, D.A.; Hinton, J.H.
1988-01-01
Reactor safety studies, such as the emergency cooling system (ECS) limits analyses and the probabilistic risk assessment, require that the flood-out times be calculated for the ac and dc motors at the -40 foot level. New calculations are needed because dams of an improved design have been installed between the pump room and motor room, and because updated leak rate calculations have shown that the maximum possible leak rate is larger than that which had been previously calculated. The methodology for calculating the motor flood-out times has also been improved. A computer program has been written to calculate flood-out times for various leak rates and sump pump operabilities. For ECS limits analyses, the worst case dc motor flood-out times are 161 and 297 seconds in LKC and P-areas, respectively. These times are for a 135,468 gpm leak that first flows to the motor room and all of the sump pumps are off
Improving Power Quality in AC Supply Grids
Directory of Open Access Journals (Sweden)
Piotr Fabijański
2015-12-01
Full Text Available This paper describes a digital and actual model of the UPQC (Unified Power Quality Conditioner integrated system for power quality improvement. The UPQC’s design and its connection to an AC supply grid, 1-phase and 3-phase alike, provide effective compensation of unwanted interferences in the waveforms of load supply voltages and non-linear load currents. This article presents an overview of topologies and control strategies. The study of the UPQC confirmed its positive impact on the power quality. The electricity parameters were significantly improved. Total harmonic distortion in supply voltage THDu decreased six-fold to 1.89%, and total harmonic distortion in load current THDi decreased more than ten-fold to 2.38% for a non-linear load (uncontrolled bridge rectifier with load L. Additionally, symmetrisation of supply voltages and reactive power compensation Q of linear load was obtained. The UPQC integrated system for power quality improvement can be used wherever high-quality and PN-EN 50160 standard – compliant electricity is required.
Neurinoma central do nervo acústico
Directory of Open Access Journals (Sweden)
Paulo Pinto Pupo
1950-03-01
Full Text Available O autor apresenta o caso de uma paciente com 45 anos, com hipertensão arterial, queixando-se de tonturas e surdez progressiva à esquerda que, ao exame neurológico, apresentava síndrome protuberancial, com hemi-anestesia táctil e dolorosa à direita respeitando a face, hemiparesia direita, ataxia de tipo sensitivo nos membros da direita, paralisia facial de tipo periférico, hipoacusia, paresia de motor ocular externo à esquerda, síndrome vertiginosa e nistagmo horizontal ao olhar para a direita. À necrópsia foi encontrado um tumor na hemicalota protuberancial esquerda e foco malácico adjacente, secundário a distúrbio circulatório. O tumor, intimamente dependente das raízes intraprotuberanciais do nervo acústico, se apresentava com as características histológicas dos neurinomas. Além dessas particularidades, a lesão do feixe central da calota e conseqüente degeneração "hipertrófica" da oliva bulbar constituem outro aspecto de grande interêsse dêste caso.
Introduction of hvdc transmission into a predominantly ac network
Energy Technology Data Exchange (ETDEWEB)
Casson, W; Last, F H; Huddart, K W
1966-02-01
Methods for reinforcing the supply network, including systems employing dc links, without introducing a new primary network are briefly described. The arrangement for dc links is outlined and the application to an existing ac system is considered. The economics of ac and dc for reinforcement schemes are briefly mentioned.
Low ac loss geometries in YBCO coated conductors
International Nuclear Information System (INIS)
Duckworth, R.C.; List, F.A.; Paranthaman, M.P.; Rupich, M.W.; Zhang, W.; Xie, Y.Y.; Selvamanickam, V.
2007-01-01
Reduction of ac losses in applied ac fields can be accomplished through either the creation of filaments and bridging in YBCO coated conductors or by an assembly of narrow width YBCO tapes. The ac losses for each of these geometries were measured at 77 K in perpendicular ac fields up to 100 mT. Despite physical isolation of the filaments, coupling losses were still present in the samples when compared to the expected hysteretic loss. In addition to filamentary conductors the assembly of stacked YBCO conductor provides an alternative method of ac loss reduction. When compared to a 4-mm wide YBCO coated conductor with a critical current of 60 A, the ac loss in a stack of 2-mm wide YBCO coated conductors with a similar total critical current was reduced. While the reduction in ac loss in a 2-mm wide stack coincided with the reduction in the engineering current density of the conductor, further reduction of ac loss was obtained through the splicing of the 2-mm wide tapes with low resistance solders
Low ac loss geometries in YBCO coated conductors
Energy Technology Data Exchange (ETDEWEB)
Duckworth, R.C. [Oak Ridge National Laboratory, One Bethel Valley Road, P.O. Box 2008, MS-6305, Oak Ridge, TN 37831-6305 (United States)], E-mail: duckworthrc@ornl.gov; List, F.A.; Paranthaman, M.P. [Oak Ridge National Laboratory, One Bethel Valley Road, P.O. Box 2008, MS-6305, Oak Ridge, TN 37831-6305 (United States); Rupich, M.W.; Zhang, W. [American Superconductor, Two Technology Drive, Westborough, MA 01581 (United States); Xie, Y.Y.; Selvamanickam, V. [SuperPower, 450 Duane Ave, Schenectady, NY 12304 (United States)
2007-10-01
Reduction of ac losses in applied ac fields can be accomplished through either the creation of filaments and bridging in YBCO coated conductors or by an assembly of narrow width YBCO tapes. The ac losses for each of these geometries were measured at 77 K in perpendicular ac fields up to 100 mT. Despite physical isolation of the filaments, coupling losses were still present in the samples when compared to the expected hysteretic loss. In addition to filamentary conductors the assembly of stacked YBCO conductor provides an alternative method of ac loss reduction. When compared to a 4-mm wide YBCO coated conductor with a critical current of 60 A, the ac loss in a stack of 2-mm wide YBCO coated conductors with a similar total critical current was reduced. While the reduction in ac loss in a 2-mm wide stack coincided with the reduction in the engineering current density of the conductor, further reduction of ac loss was obtained through the splicing of the 2-mm wide tapes with low resistance solders.
Flexible AC transmission systems: the state of the art
Energy Technology Data Exchange (ETDEWEB)
Edris, Abdel-Aty [Electric Power Research Inst., Palo Alto, CA (United States). Electric Systems Division
1994-12-31
Flexible AC transmission systems (FACTS) is a concept promoting the use of power electronic controllers to enhance the controllability and usable capacity of AC transmission. This paper presents the state of the art of FACTS and the status of the current projects for the application of the FACTS controllers in transmission systems. (author) 8 refs., 8 figs.
Ammonia treated Mo/AC catalysts for CO hydrogenation with ...
Indian Academy of Sciences (India)
SHARIF F ZAMAN
the influence of acid treated AC as a support with K-Ni-. Mo active ... K-Ni-Mo/AC catalyst was more selective to oxygenates. (>40% ... mineral impurities (K, Si, Sn and Fe) <1%. ...... edge technical support with thanks Science and Technology.
ELECTRONIC SYSTEM FOR EXPERIMENTATION IN AC ELECTROGRAVIMETRY I: TECHNIQUE FUNDAMENTALS
Directory of Open Access Journals (Sweden)
Róbinson Torres
Full Text Available Basic fundamentals of AC electrogravimetry are introduced. Their main requirements and characteristics are detailed to establish the design of an electronic system that allows the appropriate extraction of data needed to determine the electrogravimetric transfer function (EGTF and electrochemical impedance (EI, in an experimental set-up for the AC electrogravimetry technique.
7 CFR 1737.31 - Area Coverage Survey (ACS).
2010-01-01
... an ACS are provided in RUS Telecommunications Engineering and Construction Manual section 205. (e... Studies-Area Coverage Survey and Loan Design § 1737.31 Area Coverage Survey (ACS). (a) The Area Coverage... the borrower's records contain sufficient information as to subscriber development to enable cost...
21 CFR 880.5500 - AC-powered patient lift.
2010-04-01
...) MEDICAL DEVICES GENERAL HOSPITAL AND PERSONAL USE DEVICES General Hospital and Personal Use Therapeutic Devices § 880.5500 AC-powered patient lift. (a) Identification. An AC-powered lift is an electrically powered device either fixed or mobile, used to lift and transport patients in the horizontal or other...
Effect of temperature on the AC impedance of protein
Indian Academy of Sciences (India)
The depression parameter reveals the electrical equivalent circuit for the biopolymers. The AC electrical conductivity in the biopolymers follows the universal power law. From this, it is observed that the AC conductivity is frequency dependent and the biopolymer papain obeys large polaron tunnelling model, gum acacia and ...
Effect of temperature on the AC impedance of protein and ...
Indian Academy of Sciences (India)
2016-08-26
Aug 26, 2016 ... The depression parameter reveals the electrical equivalent circuit for the biopolymers. The AC electrical conductivity in the biopolymers follows the universal power law. From this, it is observed that the AC conductivity is frequency dependent and the biopolymer papain obeys large polaron tunnelling model ...
Learning Sparse Visual Representations with Leaky Capped Norm Regularizers
Wangni, Jianqiao; Lin, Dahua
2017-01-01
Sparsity inducing regularization is an important part for learning over-complete visual representations. Despite the popularity of $\\ell_1$ regularization, in this paper, we investigate the usage of non-convex regularizations in this problem. Our contribution consists of three parts. First, we propose the leaky capped norm regularization (LCNR), which allows model weights below a certain threshold to be regularized more strongly as opposed to those above, therefore imposes strong sparsity and...
Temporal regularity of the environment drives time perception
van Rijn, H; Rhodes, D; Di Luca, M
2016-01-01
It’s reasonable to assume that a regularly paced sequence should be perceived as regular, but here we show that perceived regularity depends on the context in which the sequence is embedded. We presented one group of participants with perceptually regularly paced sequences, and another group of participants with mostly irregularly paced sequences (75% irregular, 25% regular). The timing of the final stimulus in each sequence could be var- ied. In one experiment, we asked whether the last stim...
Adapting AC Lines to DC Grids for Large-Scale Renewable Power Transmission
Directory of Open Access Journals (Sweden)
D. Marene Larruskain
2014-10-01
Full Text Available All over the world, governments of different countries are nowadays promoting the use of clean energies in order to achieve sustainable energy systems. In this scenario, since the installed capacity is continuously increasing, renewable sources can play an important role. Notwithstanding that, some important problems may appear when connecting these sources to the grid, being the overload of distribution lines one of the most relevant. In fact, renewable generation is usually connected to the nearest AC grid, although this HV system may not have been designed considering distributed generation. In the particular case of large wind farms, the electrical grid has to transmit all the power generated by wind energy and, as a consequence, the AC system may get overloaded. It is therefore necessary to determine the impact of wind power transmission so that appropriate measures can be taken. Not only are these measures influenced by the amount of power transmitted, but also by the quality of the transmitted power, due to the output voltage fluctuation caused by the highly variable nature of wind. When designing a power grid, although AC systems are usually the most economical solution because of its highly proven technology, HVDC may arise in some cases (e.g. offshore wind farms as an interesting alternative, offering some added values such as lower losses and better controllability. This way, HVDC technology can solve most of the aforementioned problems and has a good potential for future use. Additionally, the fast development of power electronics based on new and powerful semiconductor devices allow the spread of innovative technologies, such as VSC-HVDC, which can be applied to create DC grids. This paper focuses on the main aspects involved in adapting the existing overhead AC lines to DC grids, with the objective of improving the transmission of distributed renewable energy to the centers of consumption.
Mao, Jie; Sun, Xing; Cheng, Jian-Hua; Shi, Yong-Jie; Wang, Xin-Zheng; Qin, Jun-Jie; Sang, Zhi-Hong; He, Kun; Xia, Qing
2016-09-01
A 52-week feeding study in cynomolgus macaques was carried out to evaluate the safety of Bt rice Huahui 1 (HH1), a transgenic rice line expressing Cry1Ab/1Ac protein. Monkeys were fed a diet with 20% or 60% HH1 rice, 20% or 60% parental rice (Minghui 63, MH63), normal diet, normal diet spiked with purified recombinant Cry1Ab/1Ac fusion protein or bovine serum albumin (BSA) respectively. During the feeding trail, clinical observations were conducted daily, and multiple parameters, including body weight, body temperature, electrocardiogram, hematology, blood biochemistry, serum metabolome and gut microbiome were examined at regular intervals. Upon sacrifice, the organs were weighted, and the macroscopic, microscopic and electron microscopic examinations were performed. The results show no adverse or toxic effects of Bt rice HH1 or Cry1Ab/1Ac fusion protein on monkeys. Therefore, the present 52-week primate feeding study suggests that the transgenic rice containing Cry 1Ab/1Ac is equivalent to its parental rice line MH63. Copyright © 2016 Elsevier Ltd. All rights reserved.
Andrade, Marco Aurélio Brizzotti; Pérez, Nicolás; Adamowski, Julio Cezar
2015-01-01
A levitação acústica pode ser uma ferramenta valiosa para auxiliar estudantes de graduação a aprender conceitos básicos de física, tais como movimento harmônico simples, ondas acústicas estacionárias, e energia potencial. Neste artigo, apresentamos o princípio de funcionamento de um levitador acústico e explicamos como aplicar as equações básicas da acústica para determinar a força de radiação acústica que atua numa esfera em uma onda estacionária. Acoustic levitation can be a valuable too...
Characterisation of AC1: a naturally decaffeinated coffee
Directory of Open Access Journals (Sweden)
Luciana Benjamim Benatti
2012-01-01
Full Text Available We compared the biochemical characteristics of the beans of a naturally decaffeinated Arabica coffee (AC1 discovered in 2004 with those of the widely grown Brazilian Arabica cultivar "Mundo Novo" (MN. Although we observed differences during fruit development, the contents of amino acids, organic acids, chlorogenic acids, soluble sugars and trigonelline were similar in the ripe fruits of AC1 and MN. AC1 beans accumulated theobromine, and caffeine was almost entirely absent. Tests on the supply of [2-14C] adenine and enzymatic analysis of theobromine synthase and caffeine synthase in the endosperm of AC1 confirmed that, as in the leaves, caffeine synthesis is blocked during the methylation of theobromine to caffeine. The quality of the final coffee beverage obtained from AC1 was similar to that of MN.
Estimation of the Thurstonian model for the 2-AC protocol
DEFF Research Database (Denmark)
Christensen, Rune Haubo Bojesen; Lee, Hye-Seong; Brockhoff, Per B.
2012-01-01
. This relationship makes it possible to extract estimates and standard errors of δ and τ from general statistical software, and furthermore, it makes it possible to combine standard regression modelling with the Thurstonian model for the 2-AC protocol. A model for replicated 2-AC data is proposed using cumulative......The 2-AC protocol is a 2-AFC protocol with a “no-difference” option and is technically identical to the paired preference test with a “no-preference” option. The Thurstonian model for the 2-AC protocol is parameterized by δ and a decision parameter τ, the estimates of which can be obtained...... by fairly simple well-known methods. In this paper we describe how standard errors of the parameters can be obtained and how exact power computations can be performed. We also show how the Thurstonian model for the 2-AC protocol is closely related to a statistical model known as a cumulative probit model...
Successful enrichment of the ubiquitous freshwater acI Actinobacteria.
Garcia, Sarahi L; McMahon, Katherine D; Grossart, Hans-Peter; Warnecke, Falk
2014-02-01
Actinobacteria of the acI lineage are often the numerically dominant bacterial phylum in surface freshwaters, where they can account for > 50% of total bacteria. Despite their abundance, there are no described isolates. In an effort to obtain enrichment of these ubiquitous freshwater Actinobacteria, diluted freshwater samples from Lake Grosse Fuchskuhle, Germany, were incubated in 96-well culture plates. With this method, a successful enrichment containing high abundances of a member of the lineage acI was established. Phylogenetic classification showed that the acI Actinobacteria of the enrichment belonged to the acI-B2 tribe, which seems to prefer acidic lakes. This enrichment grows to low cell densities and thus the oligotrophic nature of acI-B2 was confirmed. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.
Directory of Open Access Journals (Sweden)
Dustin Kai Yan Lau
2014-03-01
Full Text Available Background Unlike alphabetic languages, Chinese uses a logographic script. However, the pronunciation of many character’s phonetic radical has the same pronunciation as the character as a whole. These are considered regular characters and can be read through a lexical non-semantic route (Weekes & Chen, 1999. Pseudocharacters are another way to study this non-semantic route. A pseudocharacter is the combination of existing semantic and phonetic radicals in their legal positions resulting in a non-existing character (Ho, Chan, Chung, Lee, & Tsang, 2007. Pseudocharacters can be pronounced by direct derivation from the sound of its phonetic radical. Conversely, if the pronunciation of a character does not follow that of the phonetic radical, it is considered as irregular and can only be correctly read through the lexical-semantic route. The aim of the current investigation was to examine reading aloud in normal adults. We hypothesized that the regularity effect, previously described for alphabetical scripts and acquired dyslexic patients of Chinese (Weekes & Chen, 1999; Wu, Liu, Sun, Chromik, & Zhang, 2014, would also be present in normal adult Chinese readers. Method Participants. Thirty (50% female native Hong Kong Cantonese speakers with a mean age of 19.6 years and a mean education of 12.9 years. Stimuli. Sixty regular-, 60 irregular-, and 60 pseudo-characters (with at least 75% of name agreement in Chinese were matched by initial phoneme, number of strokes and family size. Additionally, regular- and irregular-characters were matched by frequency (low and consistency. Procedure. Each participant was asked to read aloud the stimuli presented on a laptop using the DMDX software. The order of stimuli presentation was randomized. Data analysis. ANOVAs were carried out by participants and items with RTs and errors as dependent variables and type of stimuli (regular-, irregular- and pseudo-character as repeated measures (F1 or between subject
Insulation coordination workstation for AC and DC substations
International Nuclear Information System (INIS)
Booth, R.R.; Hileman, A.R.
1990-01-01
The Insulation Coordination Workstation was designed to aid the substation design engineer in the insulation coordination process. The workstation utilizes state of the art computer technology to present a set of tools necessary for substation insulation coordination, and to support the decision making process for all aspects of insulation coordination. The workstation is currently being developed for personal computers supporting OS/2 Presentation Manager. Modern Computer-Aided Software Engineering (CASE) technology was utilized to create an easily expandable framework which currently consists of four modules, each accessing a central application database. The heart of the workstation is a library of user-friendly application programs for the calculation of important voltage stresses used for the evaluation of insulation coordination. The Oneline Diagram is a graphic interface for data entry into the EPRI distributed EMTP program, which allows the creation of complex systems on the CRT screen using simple mouse clicks and keyboard entries. Station shielding is graphically represented in the Geographic Viewport using a three-dimensional substation model, and the interactive plotting package allows plotting of EPRI EMTP output results on the CRT screen, printer, or pen plotter. The Insulation Coordination Workstation was designed by Advanced Systems Technology (AST), a division of ABB Power Systems, Inc., and sponsored by the Electric Power Research Institute under RP 2323-5, AC/DC Insulation Coordination Workstation
Diffusion cooling of electrons in an A.C. field
International Nuclear Information System (INIS)
Robson, R.E.
1997-01-01
Boundaries affect the measured values of transport coefficients in all drift tube experiments, to a greater or lesser extent, and nowhere is this more apparent than in the experiment first devised by Cavalleri (1969) and subsequently adapted by Crompton and coworkers in the 1970s. The phenomenon of 'diffusion cooling' is particularly striking and arises essentially from a penetration of the 'boundary layer' (of thickness of the order of the mean free path for energy exchange) throughout a significant portion of the gas chamber. Although this is something of an obstacle to extracting the classical diffusion coefficient from experimental data, it is of great interest in its own right from a theoretical point of view, and the Crompton et al. experiments motivated several theoretical treatments which successfully explained diffusion cooling, albeit for zero applied field and on the basis of the 'two-term' spherical harmonic representation of the velocity distribution function. The present paper puts these theories in the context of the modern, generalised eigenvalue theory, which may be used as a basis for describing all swarm experiments. In addition, the earlier zero-field studies are generalised to the extent that an a.c. heating field is included, as was the case for the original Cavalleri experimental set-up. This field is found to enhance diffusion cooling effects for a simple model elastic collisional cross sections, by pumping electrons into the energy regime preferred for loss to the walls. 32 refs
Cosmic Shear With ACS Pure Parallels. Targeted Portion.
Rhodes, Jason
2002-07-01
Small distortions in the shapes of background galaxies by foreground mass provide a powerful method of directly measuring the amount and distribution of dark matter. Several groups have recently detected this weak lensing by large-scale structure, also called cosmic shear. The high resolution and sensitivity of HST/ACS provide a unique opportunity to measure cosmic shear accurately on small scales. Using 260 parallel orbits in Sloan i {F775W} we will measure for the first time: the cosmic shear variance on scales Omega_m^0.5, with signal-to-noise {s/n} 20, and the mass density Omega_m with s/n=4. They will be done at small angular scales where non-linear effects dominate the power spectrum, providing a test of the gravitational instability paradigm for structure formation. Measurements on these scales are not possible from the ground, because of the systematic effects induced by PSF smearing from seeing. Having many independent lines of sight reduces the uncertainty due to cosmic variance, making parallel observations ideal.
Efficient relaxations for joint chance constrained AC optimal power flow
Energy Technology Data Exchange (ETDEWEB)
Baker, Kyri; Toomey, Bridget
2017-07-01
Evolving power systems with increasing levels of stochasticity call for a need to solve optimal power flow problems with large quantities of random variables. Weather forecasts, electricity prices, and shifting load patterns introduce higher levels of uncertainty and can yield optimization problems that are difficult to solve in an efficient manner. Solution methods for single chance constraints in optimal power flow problems have been considered in the literature, ensuring single constraints are satisfied with a prescribed probability; however, joint chance constraints, ensuring multiple constraints are simultaneously satisfied, have predominantly been solved via scenario-based approaches or by utilizing Boole's inequality as an upper bound. In this paper, joint chance constraints are used to solve an AC optimal power flow problem while preventing overvoltages in distribution grids under high penetrations of photovoltaic systems. A tighter version of Boole's inequality is derived and used to provide a new upper bound on the joint chance constraint, and simulation results are shown demonstrating the benefit of the proposed upper bound. The new framework allows for a less conservative and more computationally efficient solution to considering joint chance constraints, specifically regarding preventing overvoltages.
Behrooz, Ali; Zhou, Hao-Min; Eftekhar, Ali A.; Adibi, Ali
2011-02-01
Depth-resolved localization and quantification of fluorescence distribution in tissue, called Fluorescence Molecular Tomography (FMT), is highly ill-conditioned as depth information should be extracted from limited number of surface measurements. Inverse solvers resort to regularization algorithms that penalize Euclidean norm of the solution to overcome ill-posedness. While these regularization algorithms offer good accuracy, their smoothing effects result in continuous distributions which lack high-frequency edge-type features of the actual fluorescence distribution and hence limit the resolution offered by FMT. We propose an algorithm that penalizes the total variation (TV) norm of the solution to preserve sharp transitions and high-frequency components in the reconstructed fluorescence map while overcoming ill-posedness. The hybrid algorithm is composed of two levels: 1) An Algebraic Reconstruction Technique (ART), performed on FMT data for fast recovery of a smooth solution that serves as an initial guess for the iterative TV regularization, 2) A time marching TV regularization algorithm, inspired by the Rudin-Osher-Fatemi TV image restoration, performed on the initial guess to further enhance the resolution and accuracy of the reconstruction. The performance of the proposed method in resolving fluorescent tubes inserted in a liquid tissue phantom imaged by a non-contact CW trans-illumination FMT system is studied and compared to conventional regularization schemes. It is observed that the proposed method performs better in resolving fluorescence inclusions at higher depths.
Magnesium Aminoclay-Fe3O4 (MgAC-Fe3O4 Hybrid Composites for Harvesting of Mixed Microalgae
Directory of Open Access Journals (Sweden)
Bohwa Kim
2018-05-01
Full Text Available In this paper, we describe the synthesis of magnesium aminoclay-iron oxide (MgAC-Fe3O4 hybrid composites for microalgae-harvesting application. MgAC-templated Fe3O4 nanoparticles (NPs were synthesized in different ratios of MgAC and Fe3O4 NPs. The uniform distribution of Fe3O4 NPs in the MgAC matrix was confirmed by transmission electron microscopy (TEM. According to obtained X-ray diffraction (XRD patterns, increased MgAC loading leads to decreased intensity of the composites’ (311 plane of Fe3O4 NPs. For harvesting of Chlorella sp. KR-1, Scenedesmus obliquus and mixed microalgae (Chlorella sp. KR-1/ Scenedesmus obliquus, the optimal pH was 4.0. At higher pHs, the microalgae-harvesting efficiencies fell. Sample #1, which had the highest MgAC concentration, showed the most stability: the harvesting efficiencies for Chlorella sp. KR-1, Scenedesmus obliquus, and mixed microalgae were reduced only to ~50% at pH = 10.0. The electrostatic interaction between MgAC and the Fe3O4 NPs in the hybrid samples by microalgae, as confirmed by zeta potential measurements, were attributed to the harvesting mechanisms. Moreover, the zeta potentials of the MgAC-Fe3O4 hybrid composites were reduced as pH was increased, thus diminishing the microalgae-harvesting efficiencies.
The use of regularization in inferential measurements
International Nuclear Information System (INIS)
Hines, J. Wesley; Gribok, Andrei V.; Attieh, Ibrahim; Uhrig, Robert E.
1999-01-01
Inferential sensing is the prediction of a plant variable through the use of correlated plant variables. A correct prediction of the variable can be used to monitor sensors for drift or other failures making periodic instrument calibrations unnecessary. This move from periodic to condition based maintenance can reduce costs and increase the reliability of the instrument. Having accurate, reliable measurements is important for signals that may impact safety or profitability. This paper investigates how collinearity adversely affects inferential sensing by making the results inconsistent and unrepeatable; and presents regularization as a potential solution (author) (ml)
Regularization ambiguities in loop quantum gravity
International Nuclear Information System (INIS)
Perez, Alejandro
2006-01-01
One of the main achievements of loop quantum gravity is the consistent quantization of the analog of the Wheeler-DeWitt equation which is free of ultraviolet divergences. However, ambiguities associated to the intermediate regularization procedure lead to an apparently infinite set of possible theories. The absence of an UV problem--the existence of well-behaved regularization of the constraints--is intimately linked with the ambiguities arising in the quantum theory. Among these ambiguities is the one associated to the SU(2) unitary representation used in the diffeomorphism covariant 'point-splitting' regularization of the nonlinear functionals of the connection. This ambiguity is labeled by a half-integer m and, here, it is referred to as the m ambiguity. The aim of this paper is to investigate the important implications of this ambiguity. We first study 2+1 gravity (and more generally BF theory) quantized in the canonical formulation of loop quantum gravity. Only when the regularization of the quantum constraints is performed in terms of the fundamental representation of the gauge group does one obtain the usual topological quantum field theory as a result. In all other cases unphysical local degrees of freedom arise at the level of the regulated theory that conspire against the existence of the continuum limit. This shows that there is a clear-cut choice in the quantization of the constraints in 2+1 loop quantum gravity. We then analyze the effects of the ambiguity in 3+1 gravity exhibiting the existence of spurious solutions for higher representation quantizations of the Hamiltonian constraint. Although the analysis is not complete in 3+1 dimensions - due to the difficulties associated to the definition of the physical inner product - it provides evidence supporting the definitions quantum dynamics of loop quantum gravity in terms of the fundamental representation of the gauge group as the only consistent possibilities. If the gauge group is SO(3) we find
Effort variation regularization in sound field reproduction
DEFF Research Database (Denmark)
Stefanakis, Nick; Jacobsen, Finn; Sarris, Ioannis
2010-01-01
In this paper, active control is used in order to reproduce a given sound field in an extended spatial region. A method is proposed which minimizes the reproduction error at a number of control positions with the reproduction sources holding a certain relation within their complex strengths......), and adaptive wave field synthesis (AWFS), both under free-field conditions and in reverberant rooms. It is shown that effort variation regularization overcomes the problems associated with small spaces and with a low ratio of direct to reverberant energy, improving thus the reproduction accuracy...
New regularities in mass spectra of hadrons
International Nuclear Information System (INIS)
Kajdalov, A.B.
1989-01-01
The properties of bosonic and baryonic Regge trajectories for hadrons composed of light quarks are considered. Experimental data agree with an existence of daughter trajectories consistent with string models. It is pointed out that the parity doubling for baryonic trajectories, observed experimentally, is not understood in the existing quark models. Mass spectrum of bosons and baryons indicates to an approximate supersymmetry in the mass region M>1 GeV. These regularities indicates to a high degree of symmetry for the dynamics in the confinement region. 8 refs.; 5 figs
Total-variation regularization with bound constraints
International Nuclear Information System (INIS)
Chartrand, Rick; Wohlberg, Brendt
2009-01-01
We present a new algorithm for bound-constrained total-variation (TV) regularization that in comparison with its predecessors is simple, fast, and flexible. We use a splitting approach to decouple TV minimization from enforcing the constraints. Consequently, existing TV solvers can be employed with minimal alteration. This also makes the approach straightforward to generalize to any situation where TV can be applied. We consider deblurring of images with Gaussian or salt-and-pepper noise, as well as Abel inversion of radiographs with Poisson noise. We incorporate previous iterative reweighting algorithms to solve the TV portion.
Bayesian regularization of diffusion tensor images
DEFF Research Database (Denmark)
Frandsen, Jesper; Hobolth, Asger; Østergaard, Leif
2007-01-01
Diffusion tensor imaging (DTI) is a powerful tool in the study of the course of nerve fibre bundles in the human brain. Using DTI, the local fibre orientation in each image voxel can be described by a diffusion tensor which is constructed from local measurements of diffusion coefficients along...... several directions. The measured diffusion coefficients and thereby the diffusion tensors are subject to noise, leading to possibly flawed representations of the three dimensional fibre bundles. In this paper we develop a Bayesian procedure for regularizing the diffusion tensor field, fully utilizing...