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1

Optimum Building Shapes for Energy Conservation  

ERIC Educational Resources Information Center

An approach to optimum building shape design is summarized that is based on local climate and is especially important for heat control in lower cost construction with temperature-responsive thermal characteristics. The study was supported by Istanbul Technical University. For journal availability see HE 508 931. (Author/LBH)

Berkoz, Esher Balkan

1977-01-01

2

Optimum shape of a blunt forebody in hypersonic flow  

NASA Technical Reports Server (NTRS)

The optimum shape of a blunt forebody attached to a symmetric wedge or cone is determined. The length of the forebody, its semi-thickness or base radius, the nose radius and the radius of the fillet joining the forebody to the wedge or cone are specified. The optimum shape is composed of simple curves. Thus experimental models can be built readily to investigate the utilization of aerodynamic heating for boundary layer control. The optimum shape based on the modified Newtonian theory can also serve as the preliminary shape for the numerical solution of the optimum shape using the governing equations for a compressible inviscid or viscous flow.

Maestrello, L.; Ting, L.

1989-01-01

3

Optimum blank shape design by sensitivity analysis  

Microsoft Academic Search

A method of blank shape design based on sensitivity analysis for the non-circular deep drawing process has been proposed. By assuming the final deformation shape to be a drawn cup with a uniform trimming allowance at the flange, the corresponding initial blank which gives the final shape after deformation has been found. With the aid of a well-known dynamic explicit

Hyunbo Shim; Kichan Son; Kwanghee Kim

2000-01-01

4

Hydromechanics of swimming propulsion. Part 2. Some optimum shape problems  

Microsoft Academic Search

The optimum shape problems considered in this part are for those profiles of a two-dimensional flexible plate in time-harmonic motion that will minimize the energy loss under the condition of fixed thrust and possibly also under other isoperimetric constraints. First, the optimum movement of a rigid plate is completely determined; it is necessary first to reduce the original singular form

T. Yao-Tsu Wu

1971-01-01

5

Optimization aided loop shaping for motion systems  

Microsoft Academic Search

An approach is proposed which improves the quality and speed of manual loop shaping. Loop shaping is an iterative and creative controller design procedure where the control engineer uses frequency response function (FRF) data of the plant to shape the open loop response such that it satisfies stability, performance and robustness specifications. The advantage compared to automated controller design methods

Dennis Bruijnen; R. van de Molengraft; M. Steinbuch

2006-01-01

6

Loop Quantization of Shape Dynamics  

NASA Astrophysics Data System (ADS)

Loop Quantum Gravity (LQG) is a promising approach to quantum gravity, in particular because it is based on a rigorous quantization of the kinematics of gravity. A difficult and still open problem in the LQG program is the construction of the physical Hilbert space for pure quantum gravity. This is due to the complicated nature of the Hamilton constraints. The Shape Dynamics description of General Relativity (GR) replaces the Hamilton constraints with spatial Weyl constraints, so the problem of finding the physical Hilbert space reduces to the problem of quantizing the Weyl constraints. Unfortunately, it turns out that a loop quantization of Weyl constraints is far from trivial despite their intuitive physical interpretation. A tentative quantization proposal and interpretation proposal is given in this contribution.

Koslowski, Tim A.

2015-01-01

7

Loop Quantization of Shape Dynamics  

E-print Network

Loop Quantum Gravity (LQG) is a promising approach to quantum gravity, in particular because it is based on a rigorous quantization of the kinematics of gravity. A difficult and still open problem in the LQG program is the construction of the physical Hilbert space for pure quantum gravity. This is due to the complicated nature of the Hamilton constraints. The Shape Dynamics description of General Relativity (GR) replaces the Hamilton constraints with spatial Weyl constraints, so the problem of finding the physical Hilbert space reduces to the problem of quantizing the Weyl constraints. Unfortunately, it turns out that a loop quantization of Weyl constraints is far from trivial despite their intuitive physical interpretation. A tentative quantization proposal and interpretation proposal is given in this contribution.

Tim Koslowski

2013-02-28

8

AIAA 2003-3875 OPTIMUM SHAPE DESIGN FOR  

E-print Network

- chinery blades and cooling fans operate in unsteady flow and are constantly subjected to unsteady loads the two methods. Introduction The majority of work in Aerodynamic Shape Op- timization (ASO) has been in which the flow is inherently unsteady but periodic. Helicopter rotors in forward flight, turboma

Jameson, Antony

9

Beyond singular values and loop shapes  

NASA Technical Reports Server (NTRS)

The status of singular value loop-shaping as a design paradigm for multivariable feedback systems is reviewed. It shows that this paradigm is an effective design tool whenever the problem specifications are spacially round. The tool can be arbitrarily conservative, however, when they are not. This happens because singular value conditions for robust performance are not tight (necessary and sufficient) and can severely overstate actual requirements. An alternate paradign is discussed which overcomes these limitations. The alternative includes a more general problem formulation, a new matrix function mu, and tight conditions for both robust stability and robust performance. The state of the art currently permits analysis of feedback systems within this new paradigm. Synthesis remains a subject of research.

Stein, G.

1985-01-01

10

Optimum topology and shape design of prestressed concrete bridge girders using a genetic algorithm  

Microsoft Academic Search

The purpose of this study is to optimize the topology and shape of prestressed concrete bridge girders. An optimum design\\u000a approach that uses a genetic algorithm (GA) for this purpose is presented. The cost of girders is the optimum design criterion.\\u000a The design variables are the cross-sectional dimensions of the prefabricated prestressed beams, the cross-sectional area of\\u000a the prestressing steel

Zekeriya Ayd?n; Yusuf Ayvaz

2010-01-01

11

Pattern drilling exploration: Optimum pattern types and hole spacings when searching for elliptical shaped targets  

USGS Publications Warehouse

In this study the selection of the optimum type of drilling pattern to be used when exploring for elliptical shaped targets is examined. The rhombic pattern is optimal when the targets are known to have a preferred orientation. Situations can also be found where a rectangular pattern is as efficient as the rhombic pattern. A triangular or square drilling pattern should be used when the orientations of the targets are unknown. The way in which the optimum hole spacing varies as a function of (1) the cost of drilling, (2) the value of the targets, (3) the shape of the targets, (4) the target occurrence probabilities was determined for several examples. Bayes' rule was used to show how target occurrence probabilities can be revised within a multistage pattern drilling scheme. ?? 1979 Plenum Publishing Corporation.

Drew, L.J.

1979-01-01

12

A study of the optimum field emitter shape for vacuum electronics applications  

NASA Astrophysics Data System (ADS)

A summary of a study on optimum field emitter models is introduced in this paper. Ten models of field emitter are presented and the electric field on the top of these field emitters in the given structure of triode are calculated using EMAS software. It is seen that sharp pyramid-on-post is the best shape of field emitter due to high field enhancement, reasonable mechanical stability and thermal contact, low capacitance and high transconductance.

Wang, Bao Ping; Tong, Linsu

1996-03-01

13

Measuring Shape-Dependent Looping Probability of DNA  

PubMed Central

Recently, several studies have shown that short doubled-stranded DNA (dsDNA) loops more readily than the wormlike chain model predicts. In most of these experiments, the intrinsic bendedness of dsDNA, which in theory can dramatically influence looping dynamics, was either avoided or unaccounted for. To investigate the effect of the shape of dsDNA on looping dynamics, we characterized the shapes of several synthetic dsDNA molecules of equal length but different sequences using gel electrophoresis. We then measured their looping rates using a FRET (Förster resonance energy transfer)-based assay and extracted the looping probability density known as the J factor (jM). We also used, for comparison, several dinucleotide angular parameter sets derived from the observed electrophoretic mobility to compute the jM predicted by the wormlike chain model. Although we found a strong correlation between curvature and jM, the measured jM was higher than most dinucleotide model predictions. This result suggests that it is difficult to reconcile the looping probability with the observed gel mobility within the wormlike chain model and underscores the importance of determining the intrinsic shape of dsDNA for proper theoretical analysis. PMID:23663850

Le, Tung T.; Kim, Harold D.

2013-01-01

14

Optimum shape control of flexible beams by piezo-electric actuators  

NASA Technical Reports Server (NTRS)

The utilization of piezoelectric actuators in controlling the static deformation and shape of flexible beams is examined. An optimum design procedure is presented to enable the selection of the optimal location, thickness and excitation voltage of the piezoelectric actuators in a way that would minimize the deflection of the beam to which these actuators are bonded. Numerical examples are presented to illustrate the application of the developed optimization procedure in minimizing structural deformation of beams using ceramic and polymeric piezoelectric actuators bonded to the beams with a typical bonding agent. The obtained results emphasize the importance of the devised rational produce in designing beam-actuator systems with minimal elastic distortions.

Baz, A.; Poh, S.

1987-01-01

15

Optimum mirror shapes and supports for light weight mirrors subjected to self-weight  

NASA Technical Reports Server (NTRS)

A parametric design study of light weight mirror shapes with various support conditions was performed utilizing the finite element program NASTRAN. Improvements in the mirror performance were made based on the following design criteria: (1) minimization of the optical surface wavefront variations, (2) minimization of the self-weight directly related to cost of manufacturing, and (3) optimal location of support points. A preprocessor to automatically generate a finite element model for each mirror geometry was developed in order to obtain the structural deformations systematically. Additionally, a postprocessor, which prepares an input data file for FRINGE (an optical computer code) was developed for generating the optical deflections that lead to the surface wavefront variations. Procedures and modeling techniques to achieve the optimum (the lightest and stiffest mirror shape due to self-weight) are addressed.

Cho, Myung K.; Richard, Ralph M.; Vukobratovich, Daniel

1989-01-01

16

Quantitative Evaluation of Closed-Loop-Shaped Cardiomyocyte Network by Using Ring-Shaped Electrode  

NASA Astrophysics Data System (ADS)

Re-entry of excitation in the heart is one of the abnormal phenomena that causes lethal arrhythmia and is thought to be induced by the looped structure of the excitation conduction pathway. To evaluate the geometrical pattern dependence of electrophysiological results, we fabricated three models of cardiomyocyte networks and compared their beating frequencies (BFs), amplitudes of a depolarization peak, and field potential durations (FPDs). The set of different closed-loop-shaped network models from 3 to 8 mm in length showed the same BFs, amplitudes, and FPDs independent of their loop lengths, whereas the BFs and FPDs of 60 µm small clusters, and the FPDs of the 2 mm open-line-shaped network model were different from those of a closed-loop-shaped network model. These results indicate that the mm order larger size of clusters might create lower BFs, and the closed-loop-shaped model may generate longer FPDs. They also suggest the importance of spatial arrangement control of the cardoimyocyte community for reproducible measurement of electrophysiological properties of cardiomyocytes, especially control of the closed-loop formation, which might change the waveforms of FPDs depending on the difference in the geometry and conduction pathway of the cell network.

Nomura, Fumimasa; Kaneko, Tomoyuki; Hamada, Tomoyo; Hattori, Akihiro; Yasuda, Kenji

2012-06-01

17

Feedback Control Systems Loop Shaping Design with Practical Considerations  

NASA Technical Reports Server (NTRS)

This paper describes loop shaping control design in feedback control systems, primarily from a practical stand point that considers design specifications. Classical feedback control design theory, for linear systems where the plant transfer function is known, has been around for a long time. But it s still a challenge of how to translate the theory into practical and methodical design techniques that simultaneously satisfy a variety of performance requirements such as transient response, stability, and disturbance attenuation while taking into account the capabilities of the plant and its actuation system. This paper briefly addresses some relevant theory, first in layman s terms, so that it becomes easily understood and then it embarks into a practical and systematic design approach incorporating loop shaping design coupled with lead-lag control compensation design. The emphasis is in generating simple but rather powerful design techniques that will allow even designers with a layman s knowledge in controls to develop effective feedback control designs.

Kopsakis, George

2007-01-01

18

Wall shape optimization for a thermosyphon loop featuring corrugated pipes  

NASA Astrophysics Data System (ADS)

In the present paper we address the problem of optimal wall-shape design of a single phase laminar thermosyphon loop. The model takes the buoyancy forces into account via the Boussinesq approximation. We focus our study on showing the effects of wall shape on the flow and on the temperature inside the thermosyphon. To this extend we determine the dependency of the flow rate and the increase in temperature, on the geometrical characteristics of the loop. The geometry considered is a set of axially symmetric corrugated pipes described by a set of parameters; namely the pipe inner radius, the period of the corrugation, the amplitude of the corrugation, and the ratio of expansion and contraction regions of a period of the pipe. The governing equations are solved using the Finite Element Method, in combination with an adaptive mesh refinement technique in order to capture the effects of wall shape. We characterize the effects of the amplitude and of the ratio of expansion and contraction. In particular we show that for a given fixed amplitude it is possible to find an optimal ratio of expansion and contraction that minimizes the temperature inside the thermosyphon. The results show that by adequately choosing the design parameters, the performance of the thermosyphon loop can be improved.

Rosen Esquivel, Patricio I.; ten Thije Boonkkamp, Jan H. M.; Dam, Jacques A. M.; Mattheij, Robert M. M.

2012-06-01

19

{alpha}-Shaped DNA loops induced by MutS  

SciTech Connect

DNA mismatch repair (MMR) is critical for the maintenance of genomic stability. MMR is initiated by recognition of DNA mismatches by the protein, MutS, which subsequently recruits downstream repair factors. To better understand the mechanism by which MutS identifies and specifically binds mismatched basepairs embedded in random DNA sequences, we monitored the interaction between MutS and DNA substrates using atomic force microscopy (AFM). An {alpha}-shaped DNA loop formed by the interaction between MutS and DNA, which was independent of whether or not a mismatch was present in the DNA substrate. These data indicate that MutS associates with DNA non-specifically and forms an {alpha}-loop interaction with the DNA substrate. In this conformation, MutS is able to scan two arms of DNA simultaneously for each MutS dimer formed.

Jia Yanxia [National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China); State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071 (China); Shenyang Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110015 (China); Graduate School, Chinese Academy of Sciences, Beijing (China); Bi Lijun; Li Feng; Chen Yuanyuan [National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China); Zhang Chenggang [Shenyang Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110015 (China); Zhang Xianen [State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071 (China)], E-mail: Zhangxe@sun5.ibp.ac.cn

2008-08-08

20

Why Are Some Hysteresis Loops Shaped Like a Butterfly? Bojana Drincic a  

E-print Network

Why Are Some Hysteresis Loops Shaped Like a Butterfly? Bojana Drinci´c a , Xiaobo Tan b , Dennis S The contribution of this paper is a framework for relating butterfly-shaped hysteresis maps to simple (single, a unimodal mapping is used to transform simple loops to butterfly loops. For the practically important class

Tan, Xiaobo

21

Orientation and shape control of a weight optimum free-free beam in a circular orbit  

NASA Technical Reports Server (NTRS)

In this study, the vibration and orientation control of large space structures using the linear quadratic regulator technique is investigated. Emphasis is placed on the control of both a class of optimally designed structures and uniform structures meeting the mission requirements using a long free-free beam in orbit as an example. The open loop and closed loop dynamics are compared and the transient responses are obtained to determine the effectiveness of the control system design.

Bainum, Peter M.; Satyanarayana, K.

1991-01-01

22

Practical Loop-Shaping Design of Feedback Control Systems  

NASA Technical Reports Server (NTRS)

An improved methodology for designing feedback control systems has been developed based on systematically shaping the loop gain of the system to meet performance requirements such as stability margins, disturbance attenuation, and transient response, while taking into account the actuation system limitations such as actuation rates and range. Loop-shaping for controls design is not new, but past techniques do not directly address how to systematically design the controller to maximize its performance. As a result, classical feedback control systems are designed predominantly using ad hoc control design approaches such as proportional integral derivative (PID), normally satisfied when a workable solution is achieved, without a good understanding of how to maximize the effectiveness of the control design in terms of competing performance requirements, in relation to the limitations of the plant design. The conception of this improved methodology was motivated by challenges in designing control systems of the types needed for supersonic propulsion. But the methodology is generally applicable to any classical control-system design where the transfer function of the plant is known or can be evaluated. In the case of a supersonic aerospace vehicle, a major challenge is to design the system to attenuate anticipated external and internal disturbances, using such actuators as fuel injectors and valves, bypass doors, and ramps, all of which are subject to limitations in actuator response, rates, and ranges. Also, for supersonic vehicles, with long slim type of structures, coupling between the engine and the structural dynamics can produce undesirable effects that could adversely affect vehicle stability and ride quality. In order to design distributed controls that can suppress these potential adverse effects, within the full capabilities of the actuation system, it is important to employ a systematic control design methodology such as this that can maximize the effectiveness of the control design in a methodical and quantifiable way. The emphasis is in generating simple but rather powerful design techniques that will allow even designers with a layman s knowledge in controls to develop effective feedback control designs. Unlike conventional ad hoc methodologies of feedback control design, in this approach actuator rates are incorporated into the design right from the start: The relation between actuator speeds and the desired control bandwidth of the system is established explicitly. The technique developed is demonstrated via design examples in a step-by-step tutorial way. Given the actuation system rates and range limits together with design specifications in terms of stability margins, disturbance rejection, and transient response, the procedure involves designing the feedback loop gain to meet the requirements and maximizing the control system effectiveness, without exceeding the actuation system limits and saturating the controller. Then knowing the plant transfer function, the procedure involves designing the controller so that the controller transfer function together with the plant transfer function equate to the designed loop gain. The technique also shows what the limitations of the controller design are and how to trade competing design requirements such as stability margins and disturbance rejection. Finally, the technique is contrasted against other more familiar control design techniques, like PID control, to show its advantages.

Kopasakis, George

2010-01-01

23

Optimum Structural Topology and Shape Design using Three Phase Hybrid GA and Artificial Density Method  

NASA Astrophysics Data System (ADS)

In this paper an efficient GA based Three Phase Topology Optimization algorithm which is an improvement over the Two-Phase Method developed by the team at IIT Delhi is presented. The Solid Isotropic Material with Penalization approach is outlined and Sequential Linear Programming method with move limits is utilized for solving the compliance minimization and volume minimization problems with volume and displacement constraints respectively. The need for parametric studies with various penalty factors and initial starting constraints are emphasized. The availability of accurate constraint derivatives with minimal effort is a boon but as in any NLP problem with a large number of variables, the global nature of the optimum is somewhat suspect in SIMP based method. A detailed comparison of the performances of the two phase and three phase methods and the SIMP method is presented for problems of different size and general conclusions are drawn.

Ramakrishnan, C. V.; Singh, Nidur; Sehgal, D. K.

2007-05-01

24

Optimum Shape Design for Unsteady Flows with Time-Accurate Continuous and Discrete Adjoint Methods  

E-print Network

rotors and turbomachinery blades operate in unsteady flows and are constantly subjected to unsteady loads an inverse design at Mach 0.6. Aerodynamic shape optimization of rotor airfoils in an unsteady viscous flow­Lomax turbulence model. A response-surface methodology was then employed to optimize the rotor blade. The objective

Jameson, Antony

25

Role of measurement voltage on hysteresis loop shape in Piezoresponse Force Microscopy  

SciTech Connect

The dependence of on-field and off-field hysteresis loop shape in Piezoresponse Force Microscopy (PFM) on driving voltage, Vac, is explored. A nontrivial dependence of hysteresis loop parameters on measurement conditions is observed. The strategies to distinguish between paraelectric and ferroelectric states with small coercive bias and separate reversible hysteretic and non-hysteretic behaviors are suggested. Generally, measurement of loop evolution with Vac is a necessary step to establish the veracity of PFM hysteresis measurements.

Kim, Yunseok [ORNL; Yang, J.-C. [University of California, Berkeley; Chu, Ying Hao [National Chiao Tung University, Hsinchu, Taiwan; Yu, Pu [University of California, Berkeley; Lu, X. [Xidian University, China; Jesse, Stephen [ORNL; Kalinin, Sergei V [ORNL

2012-01-01

26

The optimum shape for a rigid rotating shell enclosing an isotropic spherical planetary mass  

NASA Technical Reports Server (NTRS)

Analysis of the Dyson Sphere, an extremely advanced civilization's hypothetical construct entirely surrounding a star, shows that new stress inward to the star increases to maxima at the poles if the sphere is rotating. This is because the centrifugal force in the rotating frame of reference vanishes at zero rotational radius, which occurs at the poles. There is less of the centrifugal force at high latitudes than low to offset the star's gravity. A form is derived for a thin, rigid, rotating shell, surrounding a large pointlike mass and/or charge, which will experience the least possible net stress at every point upon it - a shape on which every point not on the shell's equator is as near as possible to being in orbit. In orbit, whose plane passes through the primary body's center of mass or of charge, F(grav), or Fg, is exactly opposite in direction to F(centrif), or Fc, and is equal in amount. At all points not on the equator, Fc will not entirely offset Fg, because of Fg's vector decomposition. However, both forces are always constrained to be equal in absolute amount everywhere on the shell, equator included. The derived shape, given by the figure of revolution around the x-axis of x = square root (y-1-72), will prove useful in large-scale space construction. Also, various engineering problems are discussed.

Covington, Tatiana

1991-01-01

27

Assessment of optimum threshold and particle shape parameter for the image analysis of aggregate size distribution of concrete sections  

NASA Astrophysics Data System (ADS)

Aggregate gradation is one of the key design parameters affecting the workability and strength properties of concrete mixtures. Estimating aggregate gradation from hardened concrete samples can offer valuable insights into the quality of mixtures in terms of the degree of segregation and the amount of deviation from the specified gradation limits. In this study, a methodology is introduced to determine the particle size distribution of aggregates from 2D cross sectional images of concrete samples. The samples used in the study were fabricated from six mix designs by varying the aggregate gradation, aggregate source and maximum aggregate size with five replicates of each design combination. Each sample was cut into three pieces using a diamond saw and then scanned to obtain the cross sectional images using a desktop flatbed scanner. An algorithm is proposed to determine the optimum threshold for the image analysis of the cross sections. A procedure was also suggested to determine a suitable particle shape parameter to be used in the analysis of aggregate size distribution within each cross section. Results of analyses indicated that the optimum threshold hence the pixel distribution functions may be different even for the cross sections of an identical concrete sample. Besides, the maximum ferret diameter is the most suitable shape parameter to estimate the size distribution of aggregates when computed based on the diagonal sieve opening. The outcome of this study can be of practical value for the practitioners to evaluate concrete in terms of the degree of segregation and the bounds of mixture's gradation achieved during manufacturing.

Ozen, Murat; Guler, Murat

2014-02-01

28

Vascularization with grids of channels: multiple scales, loops and body shapes  

NASA Astrophysics Data System (ADS)

Grid-shaped and tree-shaped flow architectures are being generated for use in vascularized materials with multiple functionality (self-healing, self-cooling, etc), based on the principle of the constructal law of evolutionary increase of flow access through the generation of better flowing configurations (designs). Here we investigate systematically the advantages of endowing the complex flow architecture with more freedom to morph. Four ways to increase design freedom are explored: multi-scale grids (one, two, three and four diameter sizes), multi-shape loops (square, triangular, hexagonal, rhombic), multi-shape bodies (hexagonal, square, rhombic) and vascularization with grids versus trees. We show that significant gains in global flow access are achieved as the number of optimized channel diameters increases. The most promising combinations of body and loop shapes are hexagonal bodies with triangular loops and square bodies with square loops. The tree-shaped architecture outperforms the grid, but it is recommendable only for stressed bodies in which the most likely location of the cracks is known ahead of time. The effect of body size on the global performance of vascularized multi-scale and multi-shape materials is documented. Diminishing returns and increasing robustness set in as the complexity of the optimized flow architectures increases.

Wang, K.-M.; Lorente, S.; Bejan, A.

2007-08-01

29

Interpolating gain-scheduled H? loop shaping design for high speed ball screw feed drives.  

PubMed

This paper presents a method to design servo controllers for flexible ball screw drives with time-varying dynamics, which are mainly due to the time-varying table position and the workpiece mass. A gain-scheduled H? loop shaping controller is designed to achieve high tracking performance against the dynamic variations. H? loop shaping design procedure incorporates open loop shaping by a set of compensators to obtain performance/robust stability tradeoffs. The interpolating gain-scheduled controller is obtained by interpolating the state space model of the linear time-invariant (LTI) controllers estimated for fixed values of the scheduling parameters and a linear least squares problem can be solved. The proposed controller has been compared with P/PI with velocity and acceleration feedforward and adaptive backstepping sliding mode control experimentally. The experimental results indicate that the tracking performance has been improved and the robustness for time-varying dynamics has been achieved with the proposed scheme. PMID:25592980

Dong, Liang; Tang, WenCheng; Bao, DaFei

2015-03-01

30

A combined application of H? loop shaping and ?-synthesis to control high-speed flywheels  

Microsoft Academic Search

The development of robust controllers for high-speed flywheel rotors supported on active magnetic bearings (AMBs) has been extensively studied over the past decade. Such flywheels can be used as energy momentum wheels (EMWs) onboard spacecraft, and pose a challenging control problem due to their high flexibility, nontrivial parametric uncertainty, and rotor-speed dependence. A combined H? loop shaping and ?-synthesis approach

Alexander Lanzon; Panagiotis Tsiotras

2005-01-01

31

Loop-shaping Design with Constant Magnitude Loci in Control Education*  

E-print Network

Loop-shaping Design with Constant Magnitude Loci in Control Education* V. CERONE, M. CANALE and D constant magnitude loci of the sensitivity function along with the well-assessed constant magnitude loci of the constant magnitude loci MT of j T j3 j (also referred to as the Hall chart, [2]) and constant magnitude

Regruto, Diego

32

Shaping Power System Inter-area Oscillations through Control Loops of Grid Integrated Wind Farms  

E-print Network

Shaping Power System Inter-area Oscillations through Control Loops of Grid Integrated Wind Farms the inter-area oscillation spectrum of a large wind-integrated power system. The power system is modeled using a contin- uum representation of the electro-mechanical swing dynamics with the wind power entering

Gayme, Dennice

33

Hindcasts and forecasts of Loop Current and eddies in the Gulf of Mexico using local ensemble transform Kalman filter and optimum-interpolation assimilation schemes  

NASA Astrophysics Data System (ADS)

The Local Ensemble Transform Kalman Filter (LETKF) is applied to the parallelized version of the Princeton Ocean Model to estimate the states of Loop Current and eddies in the Gulf of Mexico from April/20 to July/21, 2010 when detailed in situ current measurements were available. Tests are conducted to explore the sensitivity of the LETKF estimates to different parameters, and to systematic additions of different observational datasets which include satellite sea surface height anomaly (SSHA), satellite sea surface temperature (SST), and moored ADCP's. The results are compared against observations to assess model skills, and also against estimates based on a simpler optimum interpolation (OI) assimilation scheme. With appropriate values of parameters and observational errors, LETKF provides improved estimates of Loop Current and eddy. In particular, the Loop Current in the late spring to summer of 2010 underwent a shedding-reattachment-shedding process. It is shown that such a nonlinear behavior is more accurately captured by LETKF, but not by OI, due to the former's time-evolving error covariance. Finally, the accuracies of 8-week forecasts initialized from the OI and LETKF analyses and forced by reanalysis winds are compared. This period is particularly challenging to forecast because, instead of a more easily simulated westward propagation at approximately the first-mode baroclinic Rossby wave speed, the newly-shed eddy propagated very slowly, stalled, and finally decayed in the eastern Gulf. Both OI and LETKF beat persistence, but the LETKF significantly improves the eddy's position and strength throughout the 8-week forecast.

Xu, F.-H.; Oey, L.-Y.; Miyazawa, Y.; Hamilton, P.

2013-09-01

34

IMC-PID design based on model matching approach and closed-loop shaping.  

PubMed

Motivated by the limitations of the conventional internal model control (IMC), this communication addresses the design of IMC-based PID in terms of the robust performance of the control system. The IMC controller form is obtained by solving an H-infinity problem based on the model matching approach, and the parameters are determined by closed-loop shaping. The shaping of the closed-loop transfer function is considered both for the set-point tracking and for the load disturbance rejection. The design procedure is formulated as a multi-objective optimization problem which is solved by a specific optimization algorithm. A nice feature of this design method is that it permits a clear tradeoff between robustness and performance. Simulation examples show that the proposed method is effective and has a wide applicability. PMID:24280534

Jin, Qi B; Liu, Q

2014-03-01

35

Shaping of Looped Miniaturized Chalcogenide Fiber Sensing Heads for Mid-Infrared Sensing  

PubMed Central

Chalcogenide glass fibers are promising photonic tools to develop Fiber Evanescent Wave Spectroscopy (FEWS) optical sensors working in the mid-infrared region. Numerous pioneering works have already been carried out showing their efficiency, especially for bio-medical applications. Nevertheless, this technology remains confined to academic studies at the laboratory scale because chalcogenide glass fibers are difficult to shape to produce reliable, sensitive and compact sensors. In this paper, a new method for designing and fabricating a compact and robust sensing head with a selenide glass fiber is described. Compact looped sensing heads with diameter equal to 2 mm were thus shaped. This represents an outstanding achievement considering the brittleness of such uncoated fibers. FEWS experiments were implemented using alcoholic solutions as target samples showing that the sensitivity is higher than with the routinely used classical fiber. It is also shown that the best compromise in term of sensitivity is to fabricate a sensing head including two full loops. From a mechanical point of view, the breaking loads of the loop shaped head are also much higher than with classical fiber. Finally, this achievement paves the way for the use of mid-infrared technology during in situ and even in vivo medical operations. Indeed, is is now possible to slide a chalcogenide glass fiber in the operating channel of a standard 2.8 mm diameter catheter. PMID:25264953

Houizot, Patrick; Anne, Marie-Laure; Boussard-Plédel, Catherine; Loréal, Olivier; Tariel, Hugues; Lucas, Jacques; Bureau, Bruno

2014-01-01

36

Shaping of looped miniaturized chalcogenide fiber sensing heads for mid-infrared sensing.  

PubMed

Chalcogenide glass fibers are promising photonic tools to develop Fiber Evanescent Wave Spectroscopy (FEWS) optical sensors working in the mid-infrared region. Numerous pioneering works have already been carried out showing their efficiency, especially for bio-medical applications. Nevertheless, this technology remains confined to academic studies at the laboratory scale because chalcogenide glass fibers are difficult to shape to produce reliable, sensitive and compact sensors. In this paper, a new method for designing and fabricating a compact and robust sensing head with a selenide glass fiber is described. Compact looped sensing heads with diameter equal to 2 mm were thus shaped. This represents an outstanding achievement considering the brittleness of such uncoated fibers. FEWS experiments were implemented using alcoholic solutions as target samples showing that the sensitivity is higher than with the routinely used classical fiber. It is also shown that the best compromise in term of sensitivity is to fabricate a sensing head including two full loops. From a mechanical point of view, the breaking loads of the loop shaped head are also much higher than with classical fiber. Finally, this achievement paves the way for the use of mid-infrared technology during in situ and even in vivo medical operations. Indeed, is is now possible to slide a chalcogenide glass fiber in the operating channel of a standard 2.8 mm diameter catheter. PMID:25264953

Houizot, Patrick; Anne, Marie-Laure; Boussard-Plédel, Catherine; Loréal, Olivier; Tariel, Hugues; Lucas, Jacques; Bureau, Bruno

2014-01-01

37

FREQ: A computational package for multivariable system loop-shaping procedures  

NASA Technical Reports Server (NTRS)

Many approaches in the field of linear, multivariable time-invariant systems analysis and controller synthesis employ loop-sharing procedures wherein design parameters are chosen to shape frequency-response singular value plots of selected transfer matrices. A software package, FREQ, is documented for computing within on unified framework many of the most used multivariable transfer matrices for both continuous and discrete systems. The matrices are evaluated at user-selected frequency-response values, and singular values against frequency. Example computations are presented to demonstrate the use of the FREQ code.

Giesy, Daniel P.; Armstrong, Ernest S.

1989-01-01

38

Optimum Shape Design for Unsteady Three-Dimensional Viscous Flows Using a Nonlinear Frequency-Domain Method  

E-print Network

and turbomachinery blades operate in unsteady flow and are constantly subjected to unsteady loads. Therefore, optimal multiplier !r = reduced frequency I. Introduction THE majority of work in aerodynamic shape optimization has on both structured and unstructured grids. Unlike fixed-wing aircraft, helicopter rotors

Jameson, Antony

39

Closed-loop control of a shape memory alloy actuation system for variable area fan nozzle  

NASA Astrophysics Data System (ADS)

Shape Memory Alloys have been used in a wide variety of actuation applications. A bundled shape memory alloy cable actuator, capable of providing large force and displacement has been developed by United Technologies Corporation (patents pending) for actuating a Variable Area fan Nozzle (VAN). The ability to control fan nozzle exit area is an enabling technology for the next generation turbofan engines. Performance benefits for VAN engines are estimated to be up to 9% in Thrust Specific Fuel Consumption (TSFC) compared to traditional fixed geometry designs. The advantage of SMA actuated VAN design is light weight and low complexity compared to conventionally actuated designs. To achieve the maximum efficiency from a VAN engine, the nozzle exit area has to be continuously varied for a certain period of time during climb, since the optimum nozzle exit area is a function of several flight variables (flight Mach number, altitude etc). Hence, the actuator had to be controlled to provide the time varying desired nozzle area. A new control algorithm was developed for this purpose, which produced the desired flap area by metering the resistive heating of the SMA actuator. Since no active cooling was used, reducing overshoot was a significant challenge of the controller. A full scale, 2 flap model of the VAN system was built, which was capable of simulating a 20% nozzle area variation, and tested under full scale aerodynamic load in NASA Langley Jet Exit Test facility. The controller met all the requirements of the actuation system and was able to drive the flap position to the desired position with less than 2% overshoot in step input tests. The controller is based on a adaptive algorithm formulation with logical switches that reduces its overshoot error. Although the effectiveness of the controller was demonstrated in full scale model tests, no theoretical results as to its stability and robustness has been derived. Stability of the controller will have to be investigated for the next stage of technology readiness.

Barooah, Prabir; Rey, Nancy

2002-07-01

40

A novel device allowing for movement and trapping of particles within loop-shaped channels  

NASA Astrophysics Data System (ADS)

Resonant excitation of a fluid cavity inside ultrasonic particle manipulation devices leads to standing waves inside the fluid. Acoustic radiation forces, caused by the nonlinear interaction between the time harmonic pressure field and a particle can be used to manipulate particles towards the nodal or anti-nodal planes of the acoustic pressure field. This allows the contactless handling of cells, bacteria or other particles, suggesting a wide range of applications in life science and medical engineering. Most ultrasonic manipulation devices described in the literature utilize reflections at fluid-structure interfaces which create the standing wave. At a given frequency, the nodal planes are fixed since their locations are governed by the geometry of the device. This reduces the suitability of the method for applications that require contactless particle transport over long distances or towards arbitrary positions. In order to overcome the described shortcoming, several methods have been proposed. In this work we introduce a new approach, leveraging circumferential resonances within a loop-shaped fluid waveguide in order to gain full one-dimensional control over the location of nodal planes. Limitations regarding the device geometry and the enclosure materials are discussed and it is described how the position or the velocity of nodal planes can be controlled via amplitude modulation applied on two transducers. Preliminary experimental results illustrate potential applications but they also reveal problems related to the current device design.

Hahn, P.; Dual, J.

2012-05-01

41

Loop-shaping H INFINITY -control of a 2DOF piezoelectric-stack actuated platform for nanoscale positioning  

Microsoft Academic Search

Piezoelectric-stack actuated platforms are utilized in many nanopositioning applications. Their performance is limited by their low-frequency resonance due to the mechanical construction as well as piezoelectric nonlinear effects. We propose a hybrid control scheme comprising a loop-shaping Hinfin controller and an inversion-based feedforward control scheme, capable of delivering accurate nanopositioning performance at relatively high speeds, upto 40 Hz. It is

Sumeet S. Aphale; Antoine Ferreira; S. O. Reza Moheimani

2009-01-01

42

Radicular Pain due to Subsidence of the Nitinol Shape Memory Loop for Stabilization after Lumbar Decompressive Laminectomy  

PubMed Central

A number of dynamic stabilization systems have been used to overcome the problems associated with spinal fusion with rigid fixation recently and the demand for an ideal dynamic stabilization system is greater for younger patients with multisegment disc degeneration. Nitinol, a shape memory alloy of nickel and titanium, is flexible at low temperatures and regains its original shape when heated, and the Nitinol shape memory loop (SML) implant has been used as a posterior tension band mostly in decompressive laminectomy cases because the Nitinol implant has various characteristics such as high elasticity and a tensile force, flexibility, and biological compatibility. The reported short-term outcomes of the application of SMLs as posterior column supporters in cervical and lumbar decompressive laminectomies seem to be positive, and complications are minimal except for the rare occurrence of pullout and fracture of the SML. However, there was no report of neurological complications related to neural compression in spite of the use of the loop of SML in the epidural space. The authors report a case of delayed development of radiating pain caused by subsidence of the SML resulting epidural compression. PMID:25674347

Kim, Deog-ryeong

2015-01-01

43

Radicular Pain due to Subsidence of the Nitinol Shape Memory Loop for Stabilization after Lumbar Decompressive Laminectomy.  

PubMed

A number of dynamic stabilization systems have been used to overcome the problems associated with spinal fusion with rigid fixation recently and the demand for an ideal dynamic stabilization system is greater for younger patients with multisegment disc degeneration. Nitinol, a shape memory alloy of nickel and titanium, is flexible at low temperatures and regains its original shape when heated, and the Nitinol shape memory loop (SML) implant has been used as a posterior tension band mostly in decompressive laminectomy cases because the Nitinol implant has various characteristics such as high elasticity and a tensile force, flexibility, and biological compatibility. The reported short-term outcomes of the application of SMLs as posterior column supporters in cervical and lumbar decompressive laminectomies seem to be positive, and complications are minimal except for the rare occurrence of pullout and fracture of the SML. However, there was no report of neurological complications related to neural compression in spite of the use of the loop of SML in the epidural space. The authors report a case of delayed development of radiating pain caused by subsidence of the SML resulting epidural compression. PMID:25674347

Son, Byung-Chul; Kim, Deog-Ryeong

2015-01-01

44

Loop Shaping Control Design for a Supersonic Propulsion System Model Using Quantitative Feedback Theory (QFT) Specifications and Bounds  

NASA Technical Reports Server (NTRS)

This paper covers the propulsion system component modeling and controls development of an integrated mixed compression inlet and turbojet engine that will be used for an overall vehicle Aero-Propulso-Servo-Elastic (APSE) model. Using previously created nonlinear component-level propulsion system models, a linear integrated propulsion system model and loop shaping control design have been developed. The design includes both inlet normal shock position control and jet engine rotor speed control for a potential supersonic commercial transport. A preliminary investigation of the impacts of the aero-elastic effects on the incoming flow field to the propulsion system are discussed, however, the focus here is on developing a methodology for the propulsion controls design that prevents unstart in the inlet and minimizes the thrust oscillation experienced by the vehicle. Quantitative Feedback Theory (QFT) specifications and bounds, and aspects of classical loop shaping are used in the control design process. Model uncertainty is incorporated in the design to address possible error in the system identification mapping of the nonlinear component models into the integrated linear model.

Connolly, Joseph W.; Kopasakis, George

2010-01-01

45

Tethered towing using open-loop input-shaping and discrete thrust levels  

NASA Astrophysics Data System (ADS)

Asteroid retrieval, satellite servicing, and debris removal concepts often rely on a thrusting vehicle to redirect and steer a passive object. One effective way to tow the object is through a tether. This study employs a discretized tether model attached to six degree-of-freedom end bodies. To reduce the risk of a post-burn collision between the end bodies, discrete thrust input shaping profiles are considered including a Posicast input and a bang-off-bang thrust profile. These input shaping techniques attain desirable collision avoidance performance by inducing a tumbling or gravity gradient motion of the tethered formation. Their performance is compared to an earlier frequency notched thruster profile.

Jasper, Lee; Schaub, Hanspeter

2014-12-01

46

Influence of fourfold anisotropy form on hysteresis loop shape in ferromagnetic nanostructures  

SciTech Connect

The dependence of the form of different mathematical depictions of fourfold magnetic anisotropies has been examined, using a simple macro-spin model. Strong differences in longitudinal and transverse hysteresis loops occur due to deviations from the usual phenomenological model, such as using absolute value functions. The proposed possible models can help understanding measurements on sophisticated magnetic nanosystems, like exchange bias layered structures employed in magnetic hard disk heads or magnetic nano-particles, and support the development of solutions with specific magnetization reversal behavior needed in novel magneto-electronic devices.

Ehrmann, Andrea [Niederrhein University of Applied Sciences, Faculty of Textile and Clothing Technology, 41065 Mönchengladbach (Germany); Blachowicz, Tomasz [Silesian University of Technology, Institute of Physics, Center for Science and Education, 44-100 Gliwice (Poland)

2014-08-15

47

Shapes  

NSDL National Science Digital Library

Welcome! Let\\'s explore the world of shapes. At Kids Online Resources (OLR) Learning is Fun, click on Shapes and see what types of everyday items are made of different simple shapes. Here is a game to play using shapes in patterns.Crack hacker's cafe If you want to make shapes into 3D forms, go to this site 2D to 3D morphing : flat 2D shapes rise up to make 3D forms and follow the directions. You may need a parent to ...

Ms. Fletcher

2007-10-23

48

Closed-loop decoder adaptation shapes neural plasticity for skillful neuroprosthetic control.  

PubMed

Neuroplasticity may play a critical role in developing robust, naturally controlled neuroprostheses. This learning, however, is sensitive to system changes such as the neural activity used for control. The ultimate utility of neuroplasticity in real-world neuroprostheses is thus unclear. Adaptive decoding methods hold promise for improving neuroprosthetic performance in nonstationary systems. Here, we explore the use of decoder adaptation to shape neuroplasticity in two scenarios relevant for real-world neuroprostheses: nonstationary recordings of neural activity and changes in control context. Nonhuman primates learned to control a cursor to perform a reaching task using semistationary neural activity in two contexts: with and without simultaneous arm movements. Decoder adaptation was used to improve initial performance and compensate for changes in neural recordings. We show that beneficial neuroplasticity can occur alongside decoder adaptation, yielding performance improvements, skill retention, and resistance to interference from native motor networks. These results highlight the utility of neuroplasticity for real-world neuroprostheses. PMID:24945777

Orsborn, Amy L; Moorman, Helene G; Overduin, Simon A; Shanechi, Maryam M; Dimitrov, Dragan F; Carmena, Jose M

2014-06-18

49

Optimum Flapping Wing Motions of Dragonfly  

NASA Astrophysics Data System (ADS)

We studied the optimum flapping wing motions of a dragonfly (Anax parthenope julius) from hovering to cruising flight at various speeds, using a 3D Navier-Stokes code coupled with an optimization algorithm. The minimum necessary power curve and optimum flapping wing motions for the various flight velocities were determined using the optimization algorithm. The minimum power curve shows the typical U-shape. The optimum flapping wing motions were evaluated by comparison with experimental data. Examining the flow patterns showed that the large-scale flow separation around the wings is suppressed at these optimum conditions, except for very low flight speeds including hovering.

Kamisawa, Yuichi; Isogai, Koji

50

Optimised sensor selection for control and fault tolerance of electromagnetic suspension systems: a robust loop shaping approach.  

PubMed

This paper presents a systematic design framework for selecting the sensors in an optimised manner, simultaneously satisfying a set of given complex system control requirements, i.e. optimum and robust performance as well as fault tolerant control for high integrity systems. It is worth noting that optimum sensor selection in control system design is often a non-trivial task. Among all candidate sensor sets, the algorithm explores and separately optimises system performance with all the feasible sensor sets in order to identify fallback options under single or multiple sensor faults. The proposed approach combines modern robust control design, fault tolerant control, multiobjective optimisation and Monte Carlo techniques. Without loss of generality, it's efficacy is tested on an electromagnetic suspension system via appropriate realistic simulations. PMID:24041402

Michail, Konstantinos; Zolotas, Argyrios C; Goodall, Roger M

2014-01-01

51

Shapes, Shapes, Shapes!  

NSDL National Science Digital Library

Let\\'s practice identifying our shapes! Look at all the choices and find the one that can Match that Shape. Help Pauly! Drag and drop to Match the Shapes! Listen closely to what color we should Paint the Shapes. ...

Miss Stringfield

2008-11-17

52

The Kissing-Loop T-Shaped Structure Translational Enhancer of Pea Enation Mosaic Virus Can Bind Simultaneously to Ribosomes and a 5? Proximal Hairpin  

PubMed Central

The Pea Enation Mosaic Virus (PEMV) 3? translational enhancer, known as the kissing-loop T-shaped structure (kl-TSS), binds to 40S subunits, 60S subunits, and 80S ribosomes, whereas the Turnip crinkle virus (TCV) TSS binds only to 60S subunits and 80S ribosomes. Using electrophoretic mobility gel shift assay (EMSA)-based competition assays, the kl-TSS was found to occupy a different site in the ribosome than the P-site-binding TCV TSS, suggesting that these two TSS employ different mechanisms for enhancing translation. The kl-TSS also engages in a stable, long-distance RNA-RNA kissing-loop interaction with a 12-bp 5?-coding-region hairpin that does not alter the structure of the kl-TSS as revealed by molecular dynamics simulations. Addition of the kl-TSS in trans to a luciferase reporter construct containing either wild-type or mutant 5? and 3? PEMV sequences suppressed translation, suggesting that the kl-TSS is required in cis to function, and both ribosome-binding and RNA interaction activities of the kl-TSS contributed to translational inhibition. Addition of the kl-TSS was more detrimental for translation than an adjacent eIF4E-binding 3? translational enhancer known as the PTE, suggesting that the PTE may support the ribosome-binding function of the kl-TSS. Results of in-line RNA structure probing, ribosome filter binding, and high-throughput selective 2?-hydroxyl acylation analyzed by primer extension (hSHAPE) of rRNAs within bound ribosomes suggest that kl-TSS binding to ribosomes and binding to the 5? hairpin are compatible activities. These results suggest a model whereby posttermination ribosomes/ribosomal subunits bind to the kl-TSS and are delivered to the 5? end of the genome via the associated RNA-RNA interaction, which enhances the rate of translation reinitiation. PMID:23986599

Gao, Feng; Gulay, Suna P.; Kasprzak, Wojciech; Dinman, Jonathan D.

2013-01-01

53

Optimum FIR array filters  

NASA Astrophysics Data System (ADS)

An optimum finite impulse response (FIR) filter bank is derived that recovers a desired signal from an array of sensors in the presence of random sensor noise and one or more coherent interfering noise sources. The required filter order is determined by the relative delays between the signal and coherent noise at each sensor, and is independent of the time duration of either the signal or coherent noise. Usually, the presence of only three sensors is sufficient to be able to eliminate the effect of coherent noise sources provided the filter order M is sufficiently large.

Williamson, Darrell; Musumeci, Phillip C.; Teo, Kok Lay

1988-08-01

54

The optimum spanning catenary cable  

NASA Astrophysics Data System (ADS)

A heavy cable spans two points in space. There exists an optimum cable length such that the maximum tension is minimized. If the two end points are at the same level, the optimum length is 1.258 times the distance between the ends. The optimum lengths for end points of different heights are also found.

Wang, C. Y.

2015-03-01

55

Optimum performance and potential flow field of hovering rotors  

NASA Technical Reports Server (NTRS)

Rotor and propeller performance and induced potential flowfields were studied on the basis of a rotating actuator disk concept, with special emphasis on rotors hovering out of ground effect. A new theory for the optimum performance of rotors hovering OGE is developed and presented. An extended theory for the optimum performance of rotors and propellers in axial motion is also presented. Numerical results are presented for the optimum distributions of blade-bound circulation together with axial inflow and ultimate wake velocities for the hovering rotor over the range of thrust coefficient of interest in rotorcraft applications. Shapes of the stream tubes and of the velocities in the slipstream are obtained, using available methods, for optimum and off-optimum circulation distributions for rotors hovering in and out of ground effect. A number of explicit formulae useful in computing rotor and propeller induced flows are presented for stream functions and velocities due to distributions of circular vortices over axi-symmetric surfaces.

Wu, J. C.; Sigman, R. K.

1975-01-01

56

OPTIMUM PLASMA STATES FOR NEXT STEP TOKAMAKS  

SciTech Connect

OAK A271 OPTIMUM PLASMA STATES FOR NEXT STEP TOKAMAKS. The dependence of the ideal ballooning {beta} limit on aspect ratio, A, and elongation {kappa} is systematically explored for nearly 100% bootstrap current driven tokamak equilibria in a wide range of the shape parameters (A = 1.2-7.0, {kappa} = 1.5-6.0 with triangularity {delta} = 0.5). The critical {beta}{sub N} is shown to be optimal at {kappa} = 3.0-4.0 for all A studied and increases as A decreases with a dependence close to A{sup -0.5}. The results obtained can be used as a theoretical basis for the choice of optimum aspect ratio and elongation of next step burning plasma tokamaks or tokamak reactors.

LIN-LIU,YR; STAMBAUGH,RD

2002-11-01

57

Optimum strong-motion array geometry for source inversion - II  

USGS Publications Warehouse

Optimum strong-motion array geometry for source inversions is determined for each of three types of earthquake faults: strike-slip, dip-slip and offshore subduction thrust. It is found that the complete Green's function is capable of stabilizing the accuracy of an inversion solution obtained using theoretical seismograms, regardless of the differences in array configuration. The optimum strong-motion array for a strike-slip fault is characterized by stations well distributed in azimuth, while the optimum array for a dip-slip event has stations arranged in a grid-shaped form. -from Author

Iida, M.

1990-01-01

58

Loop shaping of structural dynamics  

E-print Network

Matrix. 31 10 Structure in Laboratory. 11 Impact Hammer. 12 Impact Force for 1 Floor: (a) Time History; (b) FFT. 36 39 39 13 Accelerometer. 40 14 Unfiltered Acceleration Time Histories for the 1" Floor Impact: (a) 1 Floor; (b) 2" Floor; (c) 3... histories of the measured input force and output accelerations. Noise within the collected data is removed by a wavelet de-noising technique. Unit pulse responses are obtained using both Fourier fast transform (FFT) and inverse Fourier fast transform...

Kim, Byeong Hwa

1999-01-01

59

EXTREME-ULTRAVIOLET MULTI-WAVELENGTH OBSERVATIONS OF QUASI-PERIODIC PULSATIONS IN A SOLAR POST-FLARE CUSP-SHAPE LOOP WITH SDO/AIA  

SciTech Connect

We present extreme-ultraviolet multi-wavelength observations with the SDO/AIA instruments of quasi-periodic pulsations (QPPs) propagating along a cusp-shaped loop formed after an M2.2 flare on the Sun. Our motivation is to detect whether there were slow-mode magnetoacoustic waves propagating along its protruding flux tube. To this end, with fast Fourier transform we extract the short (<3 minutes) and long (>3 minutes) period components of the QPPs from time-space diagrams of the tube slices. We find that velocity differences did exist among the short/long-period components of different wavelengths, but only one event in the long-period ones showed they were greater than the measurement errors (e.g., 65 km s{sup -1}), which were 330 km s{sup -1} detected in 171 A, 590 km s{sup -1} in 211 A, and 180 km s{sup -1} in 304 A. The intensity modulation in all wavelengths is found to be very large, e.g., {approx}60% of the emission trend for an event in the 171 A passband, which would be an order of magnitude higher than the perturbation of the plasma density in the slow-mode magnetoacoustic waves. Moreover, only the QPPs with upward velocities of 50-300 km s{sup -1} are found in the tube, and the downward ones of several tens of kilometers are never unambiguously detected. Therefore, most of the QPP events under study were likely the episodic outflows along the tube, and the one with a supersonic speed of 590 km s{sup -1} may be a kink wave.

Su, J. T. [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Science, Beijing 100012 (China); Shen, Y. D.; Liu, Y. [National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, Kunming 650011 (China)

2012-07-20

60

FISHER'S GEOMETRIC MODEL WITH A MOVING OPTIMUM  

PubMed Central

Fisher's geometric model has been widely used to study the effects of pleiotropy and organismic complexity on phenotypic adaptation. Here, we study a version of Fisher's model in which a population adapts to a gradually moving optimum. Key parameters are the rate of environmental change, the dimensionality of phenotype space, and the patterns of mutational and selectional correlations. We focus on the distribution of adaptive substitutions, that is, the multivariate distribution of the phenotypic effects of fixed beneficial mutations. Our main results are based on an “adaptive-walk approximation,” which is checked against individual-based simulations. We find that (1) the distribution of adaptive substitutions is strongly affected by the ecological dynamics and largely depends on a single composite parameter ?, which scales the rate of environmental change by the “adaptive potential” of the population; (2) the distribution of adaptive substitution reflects the shape of the fitness landscape if the environment changes slowly, whereas it mirrors the distribution of new mutations if the environment changes fast; (3) in contrast to classical models of adaptation assuming a constant optimum, with a moving optimum, more complex organisms evolve via larger adaptive steps. PMID:24898080

Matuszewski, Sebastian; Hermisson, Joachim; Kopp, Michael

2014-01-01

61

Using Signal Detection Theory and Time Window-based Human-In-The-Loop simulation as a tool for assessing the effectiveness of different qualitative shapes in continuous monitoring tasks.  

PubMed

This paper provides a case study of Signal Detection Theory (SDT) as applied to a continuous monitoring dual-task environment. Specifically, SDT was used to evaluate the independent contributions of sensitivity and bias to different qualitative gauges used in process control. To assess detection performance in monitoring the gauges, we developed a Time Window-based Human-In-The-Loop (TWHITL) simulation bed. Through this test bed, we were able to generate a display similar to those monitored by console operators in oil and gas refinery plants. By using SDT and TWHITL, we evaluated the sensitivity, operator bias, and response time of flow, level, pressure, and temperature gauge shapes developed by Abnormal Situation Management(®) (ASM(®)) Consortium (www.asmconsortium.org). Our findings suggest that display density influences the effectiveness of participants in detecting abnormal shapes. Furthermore, results suggest that some shapes elicit better detection performance than others. PMID:24079651

Kim, Jung Hyup; Rothrock, Ling; Laberge, Jason

2014-05-01

62

Performance characteristics of aerodynamically optimum turbines for wind energy generators  

NASA Technical Reports Server (NTRS)

This paper presents a brief discussion of the aerodynamic methodology for wind energy generator turbines, an approach to the design of aerodynamically optimum wind turbines covering a broad range of design parameters, some insight on the effect on performance of nonoptimum blade shapes which may represent lower fabrication costs, the annual wind turbine energy for a family of optimum wind turbines, and areas of needed research. On the basis of the investigation, it is concluded that optimum wind turbines show high performance over a wide range of design velocity ratios; that structural requirements impose constraints on blade geometry; that variable pitch wind turbines provide excellent power regulation and that annual energy output is insensitive to design rpm and solidity of optimum wind turbines.

Rohrbach, C.; Worobel, R.

1975-01-01

63

Optimum size of nanorods for heating application  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles (MNP's) have become increasingly important in heating applications such as hyperthermia treatment of cancer due to their ability to release heat when a remote external alternating magnetic field is applied. It has been shown that the heating capability of such particles varies significantly with the size of particles used. In this paper, we theoretically evaluate the heating capability of rod-shaped MNP's and identify conditions under which these particles display highest efficiency. For optimally sized monodisperse particles, the power generated by rod-shaped particles is found to be equal to that generated by spherical particles. However, for particles which are not mono dispersed, rod-shaped particles are found to be more effective in heating as a result of the greater spread in the power density distribution curve. Additionally, for rod-shaped particles, a dispersion in the radius of the particle contributes more to the reduction in loss power when compared to a dispersion in the length. We further identify the optimum size, i.e the radius and length of nanorods, given a bi-variate log-normal distribution of particle size in two dimensions.

Seshadri, G.; Thaokar, Rochish; Mehra, Anurag

2014-08-01

64

Towards optimum demodulation of bandwidth-limited and low SNR square-wave subcarrier signals  

NASA Technical Reports Server (NTRS)

The optimum phase detector is presented for tracking square-wave subcarriers that have been bandwidth limited to a finite number of harmonics. The phase detector is optimum in the sense that the loop signal-to-noise ratio (SNR) is maximized and, hence, the rms phase tracking error is minimized. The optimum phase detector is easy to implement and achieves substantial improvement. Also presented are the optimum weights to combine the signals demodulated from each of the harmonics. The optimum weighting provides SNR improvement of 0.1 to 0.15 dB when the subcarrier loop SNR is low (15 dB) and the number of harmonics is high (8 to 16).

Feria, Y.; Hurd, W.

1995-01-01

65

Determination of optimum plan forms for control surfaces  

NASA Technical Reports Server (NTRS)

Solutions found for a range of airfoil plan forms indicate that, regardless of the characteristics of the tail surface, the chord of the rudder or of the elevator should be very nearly constant over its span. The optimum ailerons are also of a characteristic shape, varying little with the plan form of the wing.

Jones, Robert T; Cohen, Doris

1942-01-01

66

RECONSTRUCTING THE LOCAL TWIST OF CORONAL MAGNETIC FIELDS AND THE THREE-DIMENSIONAL SHAPE OF THE FIELD LINES FROM CORONAL LOOPS IN EXTREME-ULTRAVIOLET AND X-RAY IMAGES  

SciTech Connect

Nonlinear force-free fields are the most general case of force-free fields, but the hardest to model as well. There are numerous methods of computing such fields by extrapolating vector magnetograms from the photosphere, but very few attempts have so far made quantitative use of coronal morphology. We present a method to make such quantitative use of X-ray and EUV images of coronal loops. Each individual loop is fit to a field line of a linear force-free field, allowing the estimation of the field line's twist, three-dimensional geometry, and the field strength along it. We assess the validity of such a reconstruction since the actual corona is probably not a linear force-free field, and that the superposition of linear force-free fields is generally not itself a force-free field. To do so, we perform a series of tests on nonlinear force-free fields, described in Low and Lou. For model loops we project field lines onto the photosphere. We compare several results of the method with the original field, in particular the three-dimensional loop shapes, local twist (coronal alpha), distribution of twist in the model photosphere, and strength of the magnetic field. We find that (1) for these trial fields, the method reconstructs twist with a mean absolute deviation of at most 15% of the range of photospheric twist, (2) heights of the loops are reconstructed with a mean absolute deviation of at most 5% of the range of trial heights, and (3) the magnitude of non-potential contribution to a photospheric field is reconstructed with a mean absolute deviation of at most 10% of the maximal value.

Malanushenko, A.; Longcope, D. W.; McKenzie, D. E. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States)

2009-12-20

67

Different Conceptualizations of Optimum Development  

Microsoft Academic Search

This article discusses different conceptualizations of optimum development in adulthood. The existential perspective of Rollo May is compared to the self-actualization theory of Abraham Maslow and to transpersonal psychology. The paradigms and value assumptions underlying the different theories of personality are explicated, and social constructionism is used as an organizing frame of reference. The principal argument is that in addition

Angela Pfaffenberger

2007-01-01

68

The optimum quantity of debt  

Microsoft Academic Search

We find that the welfare gains to being at the optimum quantity of debt rather than the current US level are small, and, therefore, concerns regarding the high level of debt in the US economy may be misplaced. This finding is based on a model of a large number of infinitely lived households whose saving behavior is influenced by precautionary

S. Rao Aiyagari; Ellen R. McGrattan

1998-01-01

69

Optimum designs for superpressure balloons  

NASA Astrophysics Data System (ADS)

The elastica shape is now well known to be the best basic shape for superpressure balloon design. This shape, also known as the pumpkin, or natural shape for balloons, has been well understood since the early 1900s when it was applied to the determination of the shape of descending parachutes. The elastica shape was also investigated in the 1950s when high strength films were used to produce superpressure cylinder balloons. The need for uniform stress distribution in shells of early superpressure balloons led to a long period of the development of spherical superpressure balloons. Not until the late 1970s was the elastica shape revisited for the purpose of the producing superpressure balloons. This paper will review various development efforts in the field of superpressure design and will elaborate on the current state-of-the-art with suggestions for future developments.

Smith, M. S.; Rainwater, E. L.

2004-01-01

70

Rolling Loop Scan: An Approach Featuring Ring-Closing Metathesis for Generating Libraries of Peptides with Molecular Shapes Mimicking Bioactive Conformations or Local Folding of Peptides and Proteins.  

PubMed

Libraries of loop-containing peptides (such as the one shown schematically) can be prepared from bis-N-alkylated peptides by ring-closing metathesis. In a general solid-phase procedure the peptides are accessible by site-specific N-alkylation. Since the amino acid side chains are not involved in cyclization, they remain available for interaction with, for example, a receptor. PMID:10649324

Reichwein; Wels; Kruijtzer; Versluis; Liskamp

1999-12-16

71

Reconstructing the Local Twist of Coronal Magnetic Fields and the Three-Dimensional Shape of the Field Lines from Coronal Loops in EUV and X-Ray Images  

E-print Network

Non-linear force-free fields are the most general case of force-free fields, but the hardest to model as well. There are numerous methods of computing such fields by extrapolating vector magnetograms from the photosphere, but very few attempts have so far made quantitative use of coronal morphology. We present a method to make such quantitative use of X-Ray and EUV images of coronal loops. Each individual loop is fit to a field line of a linear force-free field, allowing the estimation of the field line's twist, three-dimensional geometry and the field strength along it. We assess the validity of such a reconstruction since the actual corona is probably not a linear force-free field and that the superposition of linear force-free fields is generally not itself a force-free field. To do so, we perform a series of tests on non-linear force-free fields, described in Low & Lou (1990). For model loops we project field lines onto the photosphere. We compare several results of the method with the original field,...

Malanushenko, A; McKenzie, D E

2009-01-01

72

Closed-loop control of intense-laser fragmentation of S{sub 8}  

SciTech Connect

A liquid-crystal-based, laser-pulse shaper has been used in combination with an adaptive genetic feedback algorithm to investigate closed-loop control of intense laser fragmentation of S{sub 8} molecules. We observe that the yield ratios S{sub N}{sup +}:S{sub M}{sup +}, for the production of specific charged fragments S{sub N}{sup +} and S{sub M}{sup +}, can be enhanced by >300% relative to those observed using transform-limited 150-fs laser pulses. We have explored the effectiveness of time- and frequency-domain pulse parametrizations while shaping either (i) only the spectral-phase distribution or (ii) the spectral-phase and amplitude distributions of the light. We find that pulse complexity, requiring control beyond simple manipulation of the peak pulse intensity and duration, is critical for optimizing the yield ratios for most species. The ''optimum'' pulse shapes obtained using different pulse parametrizations show significant differences while yielding similar signal enhancements. In some cases, comparison of the different optimum pulse shapes appears to be a useful method for identifying pulse traits that are, or are not, important for manipulating a particular yield ratio. The importance of specific traits in the optimum pulse shapes is also explored numerically using principal control analysis. We conclude that closed-loop control can be effective for optimizing highly nonlinear strong-field processes. However, in general, intensity variations in a focused laser beam severely limit one's ability to associate the optimization results with specific dynamical mechanisms that bear primary responsibility for the control.

Wells, E. [Department of Physics, University of Virginia, Charlottesville, Virginia 22904-4714 (United States); Department of Physics, Augustana College, Sioux Falls, South Dakota 57197 (United States); Betsch, K. J. [Department of Physics, Augustana College, Sioux Falls, South Dakota 57197 (United States); Conover, C. W. S. [Department of Physics and Astronomy, Colby College, Waterville, Maine 04901 (United States); DeWitt, Merrick J. [Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904-4319 (United States); Pinkham, D.; Jones, R. R. [Department of Physics, University of Virginia, Charlottesville, Virginia 22904-4714 (United States)

2005-12-15

73

Swarms: Optimum aggregations of spacecraft  

NASA Technical Reports Server (NTRS)

Swarms are aggregations of spacecraft or elements of a space system which are cooperative in function, but physically isolated or only loosely connected. For some missions the swarm configuration may be optimum compared to a group of completely independent spacecraft or a complex rigidly integrated spacecraft or space platform. General features of swarms are induced by considering an ensemble of 26 swarms, examples ranging from Earth centered swarms for commercial application to swarms for exploring minor planets. A concept for a low altitude swarm as a substitute for a space platform is proposed and a preliminary design studied. The salient design feature is the web of tethers holding the 30 km swarm in a rigid two dimensional array in the orbital plane. A mathematical discussion and tutorial in tether technology and in some aspects of the distribution of services (mass, energy, and information to swarm elements) are included.

Mayer, H. L.

1980-01-01

74

DNA looping.  

PubMed Central

DNA-looping mechanisms are part of networks that regulate all aspects of DNA metabolism, including transcription, replication, and recombination. DNA looping is involved in regulation of transcriptional initiation in prokaryotic operons, including ara, gal, lac, and deo, and in phage systems. Similarly, in eukaryotic organisms, the effects of enhancers appear to be mediated at least in part by loop formation, and examples of DNA looping by hormone receptor proteins and developmental regulatory proteins have been found. In addition, instances of looped structures have been found in replication and in recombination in both prokaryotes and eukaryotes. DNA loop formation may have different functions in different cellular contexts; in some cases, the loop itself is requisite for regulation, while in others the increase in the effective local concentration of protein may account for the effects observed. The ability of DNA to form loops is affected by the distance between binding sites; by the DNA sequence, which determines deformability and bendability; and by the presence of other proteins that exert an influence on the conformation of a particular sequence. Alteration of the stability of DNA loops and/or protein-DNA binding by extra- or intracellular signals provides responsivity to changing metabolic or environmental conditions. The fundamental property of site-specific protein binding to DNA can be combined with protein-protein and protein-ligand interaction to generate a broad range of physiological states. PMID:1579106

Matthews, K S

1992-01-01

75

Optimum reentry trajectories of a lifting vehicle  

NASA Technical Reports Server (NTRS)

Research results are presented of an investigation of the optimum maneuvers of advanced shuttle type spacecraft during reentry. The equations are formulated by means of modified Chapman variables resulting in a general set of equations for flight analysis which are exact for reentry and for flight in a vacuum. Four planar flight typical optimum manuevers are investigated. For three-dimensional flight the optimum trajectory for maximum cross range is discussed in detail. Techniques for calculating reentry footprints are presented.

Chern, J. S.; Vinh, N. X.

1980-01-01

76

Concepts for generating optimum vertical flight profiles  

NASA Technical Reports Server (NTRS)

Algorithms for generating optimum vertical profiles are derived and examined. These algorithms form the basis for the design of onboard flight management concepts. The variations in the optimum vertical profiles (resulting from these concepts) due to variations in wind, takeoff weight, and range-to-destination are presented. Further considerations for mechanizing two different onboard methods of computing near-optimum flight profiles are then outlined. Finally, the results are summarized, and recommendations are made for further work. Technical details of optimum trajectory design, steering requirements for following these trajectories, and off-line computer programs for testing the concepts are included.

Sorensen, J. A.

1979-01-01

77

Optimum hypersonic airfoil with power law shock waves  

SciTech Connect

In the present paper the flow field over a class of two-dimensional lifting surfaces is examined from the viewpoint of inviscid, hypersonic small-disturbance theory (HSDT). It is well known that a flow field in which the shock shape S(x) is similar to the body shape F(x) is only possible for F(x) = x{sup k} and the freestream Mach number M{sub {infinity}} = {infinity}. This self-similar flow has been studied for several decades as it represents one of the few existing exact solutions of the equations of HSDT. Detailed discussions are found for example in papers by Cole, Mirels, Chernyi and Gersten and Nicolai but they are limited to convex body shapes, that is, k {le} 1. The only study of concave body shapes was attempted by Sullivan where only special cases were considered. The method used here shows that similarity also exists for concave shapes and a complete solution of the flow field for any k > 2/3 is given. The effect of varying k on C{sub L}{sup 3/2}/C{sub D} is then determined and an optimum shape is found. Furthermore, a wider class of lifting surfaces is constructed using the streamlines of the basic flow field and analysed with respect to the effect on C{sub L}{sup 3/2}/C{sub D}. 9 refs., 3 figs.

Wagner, B.A.

1990-01-01

78

Optimum insulation thickness for refrigeration applications  

Microsoft Academic Search

A thermoeconomic optimization analysis is presented yielding a simple algebraic formula for estimating optimum insulation thickness for refrigeration applications. The effects of design parameters on the optimum insulation thickness are investigated for three test cities using an interactive computer code written in Fortran 77. The equivalent full load hours method is used to estimate the energy requirements.

M. S Söylemez; M Ünsal

1999-01-01

79

Optimum Reset of Ship's Inertial Navigation System  

Microsoft Academic Search

Optimum linear filter and control theory is applied to the practical problem of supplementing an inertial navigation system with discrete reference information. The information takes the form of position obtained from Loran C or Decca, for example, and occasional azimuth fixes obtained from star sightings. In particular, optimum use of this information is discussed for the Ship's Inertial Navigation System

B. E. Bona; Robert J. Smay

1966-01-01

80

Optimum signal format for pulse compression radar  

Microsoft Academic Search

The design of a pulse compression radar is discussed in terms of a receiver with normalized output defined by an ambiguity function. An optimum narrowing of the ambiguity function along the time axis yields enhanced range accuracy and resolution. Optimal autocorrelation functions having the shortest duration for the allowable sidelobe level are found using Dolph-Chebyshev polynomials, leading to optimum sidelobe

M. C. Chandra Mouly; R. C. Pande

1981-01-01

81

DEVELOPMENT OF OPTIMUM DESIGN CONFIGURATION AND  

E-print Network

DEVELOPMENT OF OPTIMUM DESIGN CONFIGURATION AND PERFORMANCE FOR VERTICAL AXIS WIND TURBINE Prepared DESIGN CONFIGURATION AND PERFORMANCE FOR VERTICAL AXIS WIND TURBINE EISG AWARDEE Mechanical and Aerospace://www.energy.ca.gov/research/index.html. #12;Page 1 Development Of Optimum Design Configuration And Performance For Vertical Axis Wind Turbine

82

Field pattern of two identical nonstaggered parallel circular loop antennas  

Microsoft Academic Search

The theoretical analysis for the field pattern of two identical coaxial circular loops is presented and the field patterns with two loops of different spacings are plotted. The realization of a fan-shaped beam for scanning purposes is discussed.

T. Bhattacharyya; K. Bandyopadhyay

1973-01-01

83

Topological defects and the optimum size of DNA condensates.  

PubMed Central

Under a wide variety of conditions, the addition of condensing agents to dilute solutions of random-coil DNA gives rise to highly compact particles that are toroidal in shape. The size of these condensates is remarkably constant and is largely independent of DNA molecular weight and basepair sequence, and of the nature of condensing agent (e.g., multivalent cation, polymers, or added cosolvent). We show how this optimum size is determined by the interactions between topological defects, which unavoidably strain the circumferentially wound DNA strands in the torus. PMID:9675173

Park, S Y; Harries, D; Gelbart, W M

1998-01-01

84

Optimum structure of Whipple shield against hypervelocity impact  

NASA Astrophysics Data System (ADS)

Hypervelocity impact of a spherical aluminum projectile onto two spaced aluminum plates (Whipple shield) was simulated to estimate an optimum structure. The Smooth Particle Hydrodynamics (SPH) code which has a unique migration scheme from a rectangular coordinate to an axisymmetic coordinate was used. The ratio of the front plate thickness to sphere diameter varied from 0.06 to 0.48. The impact velocities considered here were 6.7 km/s. This is the procedure we explored. To guarantee the early stage simulation, the shapes of debris clouds were first compared with the previous experimental pictures, indicating a good agreement. Next, the debris cloud expansion angle was predicted and it shows a maximum value of 23 degree for thickness ratio of front bumper to sphere diameter of 0.23. A critical sphere diameter causing failure of rear wall was also examined while keeping the total thickness of two plates constant. There exists an optimum thickness ratio of front bumper to rear wall, which is identified as a function of the size combination of the impacting body, front and rear plates. The debris cloud expansion-correlated-optimum thickness ratio study provides a good insight on the hypervelocity impact onto spaced target system.

Lee, M.

2014-05-01

85

Shape Savvy  

NSDL National Science Digital Library

Help your students identify these different shapes! Learn your shapes with Big Bird s Shapes and then Make Designs with Shapes to create objects! You better know your colors to Paint the Shapes correctly! ...

Ms. Popwell

2010-09-22

86

Neoclassical formulations of optimum population theory  

E-print Network

NEOCLASSICAL FORMULATIONS OF OPTIMUM POPULATION THEORY A Thesis by GLENN ANTHONY DAVIS Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE August 1971... Major Subject: Economics NEOCLASSICAL FORMULATIONS OF OPTIMUM POPULATION THEORY A Thesis by GLENN ANTHONY DAVIS Approved as to style and content by: ( rrman Committee) (Head of the Department) (Member) (Member) (Member) (Member) (Member...

Davis, Glenn Anthony

1971-01-01

87

Optimum Tapped Delay Line for Digital Signals  

Microsoft Academic Search

The problem of finding the optimum tapped delay line (TDL) gain settings for a digital communications receiver with a detection process involving a single threshold level (zero volts) is examined. Based on a minimax criterion which seeks to maximize the eye opening-to-rms noise ratio, an optimum set of tap gains is found with the aid of a geometric construction inn-dimensional

A. Guida

1973-01-01

88

Computational Complexity of Optimum Multiuser Detection  

Microsoft Academic Search

Optimum centralized demodulation of the independent data streams transmitted simultaneously by several users through a Code\\u000a Division Multiple-Access channel is considered. Each user sends an arbitrary assigned signal waveform, which is linearly modulated\\u000a by symbols drawn from a finite alphabet. If the users are asynchronous, the optimum multiuser detector can be implemented\\u000a by a Viterbi algorithm whose time-complexity is linear

Sergio Verdú

1989-01-01

89

Optimum Design of High-Speed Prop-Rotors  

NASA Technical Reports Server (NTRS)

An integrated multidisciplinary optimization procedure is developed for application to rotary wing aircraft design. The necessary disciplines such as dynamics, aerodynamics, aeroelasticity, and structures are coupled within a closed-loop optimization process. The procedure developed is applied to address two different problems. The first problem considers the optimization of a helicopter rotor blade and the second problem addresses the optimum design of a high-speed tilting proprotor. In the helicopter blade problem, the objective is to reduce the critical vibratory shear forces and moments at the blade root, without degrading rotor aerodynamic performance and aeroelastic stability. In the case of the high-speed proprotor, the goal is to maximize the propulsive efficiency in high-speed cruise without deteriorating the aeroelastic stability in cruise and the aerodynamic performance in hover. The problems studied involve multiple design objectives; therefore, the optimization problems are formulated using multiobjective design procedures. A comprehensive helicopter analysis code is used for the rotary wing aerodynamic, dynamic and aeroelastic stability analyses and an algorithm developed specifically for these purposes is used for the structural analysis. A nonlinear programming technique coupled with an approximate analysis procedure is used to perform the optimization. The optimum blade designs obtained in each case are compared to corresponding reference designs.

Chattopadhyay, Aditi; McCarthy, Thomas Robert

1993-01-01

90

Loop-to-loop coupling.  

SciTech Connect

This report estimates inductively-coupled energy to a low-impedance load in a loop-to-loop arrangement. Both analytical models and full-wave numerical simulations are used and the resulting fields, coupled powers and energies are compared. The energies are simply estimated from the coupled powers through approximations to the energy theorem. The transmitter loop is taken to be either a circular geometry or a rectangular-loop (stripline-type) geometry that was used in an experimental setup. Simple magnetic field models are constructed and used to estimate the mutual inductance to the receiving loop, which is taken to be circular with one or several turns. Circuit elements are estimated and used to determine the coupled current and power (an equivalent antenna picture is also given). These results are compared to an electromagnetic simulation of the transmitter geometry. Simple approximate relations are also given to estimate coupled energy from the power. The effect of additional loads in the form of attached leads, forming transmission lines, are considered. The results are summarized in a set of susceptibility-type curves. Finally, we also consider drives to the cables themselves and the resulting common-to-differential mode currents in the load.

Warne, Larry Kevin; Lucero, Larry Martin; Langston, William L.; Salazar, Robert Austin; Coleman, Phillip Dale; Basilio, Lorena I.; Bacon, Larry Donald

2012-05-01

91

Bryce Canyon's Navajo Loop Trail  

USGS Multimedia Gallery

Views along the Navajo Loop Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandston...

92

Optimum Finite Impulse Response (FIR) Low-Pass Filtering of Market Data  

Microsoft Academic Search

The goal of this contribution is to compare 9 cases of FIR (Finite Impulse Response) type filters, by using approximation theory based norms for the following output parameters: delay and correlation between input and output, and ``smoothness'' of the output derivative. It was found that the most commonly used rectangular shape of impulse response is in general not an optimum

A. Dyka; M. Kazmierczak

2005-01-01

93

Efficient, Nearly Optimum Addressing Schemes Based on Partitioning the Constellation into the Union of Blocks  

E-print Network

Efficient, Nearly Optimum Addressing Schemes Based on Partitioning the Constellation into the Union. Each of the source symbols is represented by one of these points. This is called a signal constellation. In selecting the boundary of a constellation (shaping region), the objective is to minimize the average energy

Kabal, Peter

94

Study of optimum methods of optical communication  

NASA Technical Reports Server (NTRS)

Optimum methods of optical communication accounting for the effects of the turbulent atmosphere and quantum mechanics, both by the semi-classical method and the full-fledged quantum theoretical model are described. A concerted effort to apply the techniques of communication theory to the novel problems of optical communication by a careful study of realistic models and their statistical descriptions, the finding of appropriate optimum structures and the calculation of their performance and, insofar as possible, comparing them to conventional and other suboptimal systems are discussed. In this unified way the bounds on performance and the structure of optimum communication systems for transmission of information, imaging, tracking, and estimation can be determined for optical channels.

Harger, R. O.

1972-01-01

95

Optimum Suction Distribution for Transition Control  

NASA Technical Reports Server (NTRS)

The optimum suction distribution which gives the longest laminar region for a given total suction is computed. The goal here is to provide the designer with a method to find the best suction distribution subject to some overall constraint applied to the suction. We formulate the problem using the Lagrangian multiplier method with constraints. The resulting non-linear system of equations is solved using the Newton-Raphson technique. The computations are performed for a Blasius boundary layer on a flat-plate and crossflow cases. For the Blasius boundary layer, the optimum suction distribution peaks upstream of the maximum growth rate region and remains flat in the middle before it decreases to zero at the end of the transition point. For the stationary and travelling crossflow instability, the optimum suction peaks upstream of the maximum growth rate region and decreases gradually to zero.

Balakumar, P.; Hall, P.

1996-01-01

96

Method for Determining Optimum Injector Inlet Geometry  

NASA Technical Reports Server (NTRS)

A method for determining the optimum inlet geometry of a liquid rocket engine swirl injector includes obtaining a throttleable level phase value, volume flow rate, chamber pressure, liquid propellant density, inlet injector pressure, desired target spray angle and desired target optimum delta pressure value between an inlet and a chamber for a plurality of engine stages. The method calculates the tangential inlet area for each throttleable stage. The method also uses correlation between the tangential inlet areas and delta pressure values to calculate the spring displacement and variable inlet geometry of a liquid rocket engine swirl injector.

Trinh, Huu P. (Inventor); Myers, W. Neill (Inventor)

2015-01-01

97

Loop Algorithm  

NASA Astrophysics Data System (ADS)

The loop algorithm for the world-line quantum Monte Carlo method on quantum lattice models is presented. After introducing the path integral representation that maps a quantum model to a classical one, we describe the continuous imaginary time limit, cluster algorithm, and the rejection free scheme, which are the major improvements on the quantum Monte Carlo technique during the last decades. By means of the loop algorithm, one can simulate various unfrustrated quantum lattice models of millions of sites at extremely low temperatures with absolute accuracy, being free from the critical and fine-mesh slowing down and the Suzuki-Trotter discretization error. We also discuss some technical aspects of the algorithm such as effective implementation and parallelization.

Todo, Synge

98

Loop Diuretics  

Microsoft Academic Search

Loop diuretics such as furosemide, piretanide, and bumetanide bind reversibly to the Na+2Cl-K+ carrier. This transporter is responsible for the uptake of Cl- into the thick ascending limb segment. As a consequence, these compounds reduce or abolish NaCl reab-sorption in this nephron segment and lead to a decreased interstitial hypertonicity and thus to a reduced water absorption. Apart from these

R. Greger; P. Wangemann

1987-01-01

99

Protein folding and loop closure: Some bioinformatics challenges  

NASA Astrophysics Data System (ADS)

Protein loop closure is a fundamental concept in protein design and structure prediction. In this paper, we show how loops play a role in shaping a protein into its native three-dimensional structure. Hence, an understanding of the protein movement at a molecular biology level is essential prior to developing practical solutions for closing loops.

Lau, N.; Oxley, A.; Nayan, M. Y.

2012-09-01

100

Transverse kink oscillations of expanding coronal loops  

E-print Network

We investigate the nature of transverse kink oscillations of loops expanding through the solar corona and how can oscillations be used to diagnose the plasma parameters and the magnetic field. In particular, we aim to analyse how the temporal dependence of the loop length (here modelling the expansion) will affect the P1 /P2 period ratio of transverse loop oscillations. Due to the uncertainty of the loop's shape through its expansion, we discuss separately the case of the loop that maintains its initial semi-circular shape and the case of the loop that from a semi-circular shape evolve into an elliptical shape loop. The equations that describe the oscillations in expanding flux tube are complicated due to the spatial and temporal dependence of coefficients. Using the WKB approximation we find approximative values for periods and their evolution, as well as the period ratio. For small values of time (near the start of the expansion) we can employ a regular perturbation method to find approximative relations fo...

Ballai, Istvan

2012-01-01

101

Optimum Transit Operations during the Emergency Evacuations  

Microsoft Academic Search

16. Abstract: The objective of this project is to provide Coast Transit Authority in Gulfport, MS an optimum transit schedule and passenger pick up routes during an emergency evacuation. This final report summarizes the methodologies, findings, and conclusions for the study objectives. The location-routing problem (LRP) with uncertain demands has been explored to develop an optimal evacuation plan for transit-dependent

Rui SONG; Shiwei HE; Li ZHANG

2009-01-01

102

The Optimum Thermal Environment for Naked Babies  

Microsoft Academic Search

The optimum thermal environment in which to nurse a baby naked in an incubator has been defined from a knowledge of the magnitude of the factors affecting thermal balance.Such a neutral environment allows body temperature to remain normal while oxygen consumption and evaporative water loss are both at a minimum.

E. N. Hey; G. Katz

1970-01-01

103

Minimum engine size for optimum automobile acceleration  

Microsoft Academic Search

The theoretical minimum for engine power rating required to accelerate a vehicle of mass {ital M} to velocity {ital V} in time {ital T} is shown to result from acceleration at constant maximum power. Because actual conditions do not allow infinite starting acceleration, the power per unit mass to provide optimum feasible acceleration with minimum engine power rating is given

Carsten M. Haaland

1992-01-01

104

OVERALL RECONSTRUCTION OPTIMUM DESIGN METHOD AND APPLICATIONS  

Microsoft Academic Search

An introduction to the significance and the difficulties of overall optimization considering technological, economical, social and environmental criteria of design problems for engineering products and projects is given. The necessity and possibility of introducing the overall reconstruction optimum design method, in theory and practice, using the reconstruction analysis (RA) system model, which has logical relations with these problems, is given.

GUANGFU SHU

2000-01-01

105

Optimum scintillator thickness for beta dosimetry  

Microsoft Academic Search

Beta particle counting by plastic scintillation counter is a convenient method of determining the beta dose rate from the natural radioactivity in soils, as required for example in the process of luminescence dating of sediments or sherds. Data is presented to establish the optimum thickness of plastic scintillator for such beta dosimetry, found to be about 6 mm.

R. B. Galloway

1994-01-01

106

Optimum Design of Coal Gasification Plants  

E-print Network

This paper deals with the optimum design of heat recovery systems using the Texaco Coal Gasification Process (TCGP). TCGP uses an entrained type gasifier and produces hot gases at approximately 2500oF with high heat flux. This heat is removed...

Pohani, B. P.; Ray, H. P.; Wen, H.

1982-01-01

107

Optimum ethane recovery in conventional turboexpander process  

Microsoft Academic Search

Ethane recovery in a conventional turboexpander process is optimized considering different demethanizer pressures and different feeds: a lean gas and a rich one. The design variables are varied, while meeting process constraints, in order to find the optimum conditions achieving the maximum profit. The analysis covers the whole process including the refrigeration part, and the entire typical demethanizer pressure range.

R. Chebbi; N. S. Al-Amoodi; N. M. Abdel Jabbar; G. A. Husseini; K. A. Al Mazroui

2010-01-01

108

Many Ways to Loop DNA  

PubMed Central

In the 1960s, I developed methods for directly visualizing DNA and DNA-protein complexes using an electron microscope. This made it possible to examine the shape of DNA and to visualize proteins as they fold and loop DNA. Early applications included the first visualization of true nucleosomes and linkers and the demonstration that repeating tracts of adenines can cause a curvature in DNA. The binding of DNA repair proteins, including p53 and BRCA2, has been visualized at three- and four-way junctions in DNA. The trombone model of DNA replication was directly verified, and the looping of DNA at telomeres was discovered. PMID:24005675

Griffith, Jack D.

2013-01-01

109

Shape Cutter  

NSDL National Science Digital Library

"With this tool, you can explore how to decompose shapes and recompose them to make other shapes. You can draw and cut shapes and also use slides, turns, and flips to move pieces around" from NCTM Illuminations.

Illuminations National Council of Teachers of Mathematics

2010-03-04

110

Shape Explorer  

NSDL National Science Digital Library

Learn the relationship between perimeter and area. A random shape will be automatically generated. Calculate the area and perimeter of this shape. Shape Explorer is one of the Interactivate assessment explorers.

111

Shape Hunt  

NSDL National Science Digital Library

Students will go on a shape hunt in the classroom or designated area. During the shape hunt, students will draw pictures of the shapes they find and the object that it is found by, in order to show the position of the shape. After the shape hunt, students will use Timed-Pair-Share to explain to peers what shapes they found and their relative positions.

Meghan Hauptli

2012-06-11

112

Water Stream "Loop-the-Loop"  

ERIC Educational Resources Information Center

Discusses the design of a modified loop-the-loop apparatus in which a water stream is used to illustrate centripetal forces and phenomena of high-velocity hydrodynamics. Included are some procedures of carrying out lecture demonstrations. (CC)

Jefimenko, Oleg

1974-01-01

113

Shape Up  

NSDL National Science Digital Library

Get a better understanding of the importance of our basic geometric shapes. While going through the activity below see if you can create the following shapes: A triangle, square, parallelogram, trapezoid, rectangle, kite, diamond. Having fun with quadrilaterals Now that you can create basic shapes see if you can create more difficult shapes on the geoboard. Geoboard Activity See if you can use the geoboard to create 3-D shapes ...

Mr. Shane Carter

2006-10-23

114

Shape Changing Airfoil  

NASA Technical Reports Server (NTRS)

Scoping of shape changing airfoil concepts including both aerodynamic analysis and materials-related technology assessment effort was performed. Three general categories of potential components were considered-fan blades, booster and compressor blades, and stator airfoils. Based on perceived contributions to improving engine efficiency, the fan blade was chosen as the primary application for a more detailed assessment. A high-level aerodynamic assessment using a GE90-90B Block 4 engine cycle and fan blade geometry indicates that blade camber changes of approximately +/-4deg would be sufficient to result in fan efficiency improvements nearing 1 percent. Constraints related to flight safety and failed mode operation suggest that use of the baseline blade shape with actuation to the optimum cruise condition during a portion of the cycle would be likely required. Application of these conditions to the QAT fan blade and engine cycle was estimated to result in an overall fan efficiency gain of 0.4 percent.

Ott, Eric A.

2005-01-01

115

Optimum damping locations for structural vibration control  

NASA Technical Reports Server (NTRS)

A technique for determining the optimum damper locations and damping rates for a flexible structure has been developed. Using a nonlinear-mathematical-programming algorithm, a diagonal damping matrix is determined such that specified modes have a prescribed modal damping ratio. The design objective is to minimize the total damping effort while constraining the modal damping ratio to be equal or greater than the prescribed amount. Additional constraints require the diagonal elements of the damping matrix to be positive which guarantees that all modes of the damped system will be stable. Results are shown for a uniform free-free beam.

Horner, G. C.

1982-01-01

116

Runge-Kutta formulas of optimum stability  

E-print Network

RUNGE-KUTTA FOK'IULAS OF OPTIMUM STABILITY A Thesis by HECTOR GONZALES SIERRA Submitted. to the Graduate College of Texas ASM University in partial fulfillment of the requirement for tno degree of MASTER OF SCIENCE May 196$ Major Subject... Mathematics RUNGE ? KUTTA 1'OR1'IULAS OP OPTI11U1, STABILITY A Thesis by RECTOR GONZALES SIERRA Approved as to style and content by: (Chairman of Committee 1ead of Departmen member Nay 1$6a ABSTRACT RAGE-KUTTA PORKJLAS OP OPTIKJN STAl3ILI1Y. (Nay I...

Sierra, Hector Gonzales

1969-01-01

117

Characterization of NIa Protease from Turnip Mosaic Potyvirus Exhibiting a Low-Temperature Optimum Catalytic Activity  

Microsoft Academic Search

Nuclear inclusion protein a (NIa) protease of turnip mosaic potyvirus is responsible for the processing of the viral polyprotein into functional proteins. The NIa protease was found to exhibit its optimum catalytic activity at approximately 15° and a bell-shaped pH-dependent activity profile with a maximum at approximately pH 8.5. Kinetic studies showed that bothKmandVmaxvalues were lower at 12 than at

Do-Hyung Kim; Duk Chul Hwang; Byoung Heon Kang; Jisun Lew; Kwan Yong Choi

1996-01-01

118

PID controller auto-tuning based on process step response and damping optimum criterion.  

PubMed

This paper presents a novel method of PID controller tuning suitable for higher-order aperiodic processes and aimed at step response-based auto-tuning applications. The PID controller tuning is based on the identification of so-called n-th order lag (PTn) process model and application of damping optimum criterion, thus facilitating straightforward algebraic rules for the adjustment of both the closed-loop response speed and damping. The PTn model identification is based on the process step response, wherein the PTn model parameters are evaluated in a novel manner from the process step response equivalent dead-time and lag time constant. The effectiveness of the proposed PTn model parameter estimation procedure and the related damping optimum-based PID controller auto-tuning have been verified by means of extensive computer simulations. PMID:24035643

Pavkovi?, Danijel; Polak, Siniša; Zorc, Davor

2014-01-01

119

Optimization of the axial power shape in pressurized water reactors  

E-print Network

Analytical and numerical methods have been applied to find the optimum axial power profile in a PWR with respect to uranium utilization. The preferred shape was found to have a large central region of uniform power density, ...

Melik, M. A.

1981-01-01

120

Leaf Shape  

NSDL National Science Digital Library

This illustrated guide is designed to help students recognize and learn the different types of leaf shapes. The single Web page, which can be easily printed for use at field sites, shows five leaf shapes.

121

Shape Builder  

NSDL National Science Digital Library

This activity operates in one of two modes: auto draw and create shape mode, allowing you to explore relationships between area and perimeter. Shape Builder is one of the Interactivate assessment explorers.

122

Shape Up!  

NSDL National Science Digital Library

In this lesson students will compare two and three dimensional shapes (circle, square, triangle, rectangle, cone, cylinder, sphere, cube) by differentiating them according to attributes. Students explain attributes of shapes by exploring real world objects.

2013-01-21

123

Stable Shapes  

NSDL National Science Digital Library

In this activity (located on page 9 of PDF), learners compare the stability of a triangle- and square-shaped structure. Learners use straws and paper clips to construct the shapes and then press down on the tops to see which shape collapses. Learners are then encouraged to build stronger shapes, perhaps by using diagonal cross-pieces as triangular bases. Use this activity to introduce compression force and structural stability.

2012-03-22

124

Demonstration of Automatically-Generated Adjoint Code for Use in Aerodynamic Shape Optimization  

NASA Technical Reports Server (NTRS)

Gradient-based optimization requires accurate derivatives of the objective function and constraints. These gradients may have previously been obtained by manual differentiation of analysis codes, symbolic manipulators, finite-difference approximations, or existing automatic differentiation (AD) tools such as ADIFOR (Automatic Differentiation in FORTRAN). Each of these methods has certain deficiencies, particularly when applied to complex, coupled analyses with many design variables. Recently, a new AD tool called ADJIFOR (Automatic Adjoint Generation in FORTRAN), based upon ADIFOR, was developed and demonstrated. Whereas ADIFOR implements forward-mode (direct) differentiation throughout an analysis program to obtain exact derivatives via the chain rule of calculus, ADJIFOR implements the reverse-mode counterpart of the chain rule to obtain exact adjoint form derivatives from FORTRAN code. Automatically-generated adjoint versions of the widely-used CFL3D computational fluid dynamics (CFD) code and an algebraic wing grid generation code were obtained with just a few hours processing time using the ADJIFOR tool. The codes were verified for accuracy and were shown to compute the exact gradient of the wing lift-to-drag ratio, with respect to any number of shape parameters, in about the time required for 7 to 20 function evaluations. The codes have now been executed on various computers with typical memory and disk space for problems with up to 129 x 65 x 33 grid points, and for hundreds to thousands of independent variables. These adjoint codes are now used in a gradient-based aerodynamic shape optimization problem for a swept, tapered wing. For each design iteration, the optimization package constructs an approximate, linear optimization problem, based upon the current objective function, constraints, and gradient values. The optimizer subroutines are called within a design loop employing the approximate linear problem until an optimum shape is found, the design loop limit is reached, or no further design improvement is possible due to active design variable bounds and/or constraints. The resulting shape parameters are then used by the grid generation code to define a new wing surface and computational grid. The lift-to-drag ratio and its gradient are computed for the new design by the automatically-generated adjoint codes. Several optimization iterations may be required to find an optimum wing shape. Results from two sample cases will be discussed. The reader should note that this work primarily represents a demonstration of use of automatically- generated adjoint code within an aerodynamic shape optimization. As such, little significance is placed upon the actual optimization results, relative to the method for obtaining the results.

Green, Lawrence; Carle, Alan; Fagan, Mike

1999-01-01

125

Shape Detective  

NSDL National Science Digital Library

The students will identify and describe shapes (squares, circles, triangles, rectangles, and hexagons). The students will also be able to correctly name shapes regardless of their orientations or overall size by becoming detectives and going in a "hunt" to find the needed shapes.

carissa curran

2012-06-11

126

Same Shapes  

NSDL National Science Digital Library

This problem challenges and extends students' spatial awareness with 2D shapes. The students are given three different irregular shapes. The goal is to divide each of them into two parts that are exactly the same shape and size. The Teachers' Notes page offers rationale, suggestions for implementation with a link to Happy Halving (cataloged seperately), discussion questions, and ideas for extension and support.

127

Optimum design of geodesically stiffened composite plates  

NASA Technical Reports Server (NTRS)

With the goal of tailorability in mind, the in-plane stiffness characteristics of a particular grid stiffened plate configuration under axial and shear loads have been studied. The contribution of the skin to the stiffener network and the resultant skin/rib interaction is analyzed. For the given plate geometry and loads, it is shown that an optimum configuration does exist. To achieve optimally designed practical plate configurations, buckling constraints need to be included in the design. Due to the complex geometry and loading of the plates, a simplified local buckling analysis of isolated stiffeners and triangular skin elements between the stiffeners is considered. Development of a stiffener buckling analysis represent stiffeners as shear deformable plate elements is presented.

Guerdal, Zafer; Phillips, John L.

1988-01-01

128

Optimum multistage genomic selection in dairy cattle.  

PubMed

The availability of different single nucleotide polymorphism (SNP) chips and the development of imputation algorithms allow for multistage dairy cattle breeding schemes applying various genomic selection strategies. These SNP genotypes yield genomically estimated breeding values (GEBV) with different accuracies at different costs. Thus, the optimum allocation of investments to different selection paths and strategies to maximize the genetic gain per year (?G(a)) and its sensitivity to changes in cost and accuracies of GEBV is of great interest. This is even more relevant under the constraints of limited financial resources. With deterministic methods, optimum multistage breeding plans maximizing ?G(a) were identified in which selection could take place on GEBV derived from high-density (GEBV(HD)) and low-density (GEBV(LD)) SNP genotypes. To account for the uncertainty of cost and accuracies of GEBV, these parameters were varied in a semi-continuous manner. Overall breeding costs were limited to the crucial expenses of a traditional breeding program with 50 progeny-tested young bulls per year. Results clearly show that, in an optimal selection strategy, selection on GEBV(LD) is predominantly used for the identification of future bull dams but the main part of ?G(a) is still generated from selection of sires. The low selection intensity in the path dam to sire induced a higher sensitivity of ?G(a) to changes in cost and accuracies of GEBV(LD) compared with the same changes of GEBV(HD). On the contrary, the genetic gain generated from selection of males was only affected by changes in accuracies of GEBV(HD) but almost unaffected by any changes in cost. Thus, changes in cost and accuracies of GEBV(LD) put the most pressure on the breeding scheme structure to maintain a high ?G(a). Furthermore, genomic selection of bull dams produced by far the majority of breeding cost but the lowest genetic gain. PMID:22459855

Börner, V; Teuscher, F; Reinsch, N

2012-04-01

129

Fast flux locked loop  

DOEpatents

A flux locked loop for providing an electrical feedback signal, the flux locked loop employing radio-frequency components and technology to extend the flux modulation frequency and tracking loop bandwidth. The flux locked loop of the present invention has particularly useful application in read-out electronics for DC SQUID magnetic measurement systems, in which case the electrical signal output by the flux locked loop represents an unknown magnetic flux applied to the DC SQUID.

Ganther, Jr., Kenneth R. (Olathe, KS); Snapp, Lowell D. (Independence, MO)

2002-09-10

130

The preprocessed doacross loop  

NASA Technical Reports Server (NTRS)

Dependencies between loop iterations cannot always be characterized during program compilation. Doacross loops typically make use of a-priori knowledge of inter-iteration dependencies to carry out required synchronizations. A type of doacross loop is proposed that allows the scheduling of iterations of a loop among processors without advance knowledge of inter-iteration dependencies. The method proposed for loop iterations requires that parallelizable preprocessing and postprocessing steps be carried out during program execution.

Saltz, Joel H.; Mirchandaney, Ravi

1990-01-01

131

An integrated optimum design approach for high speed prop rotors  

NASA Technical Reports Server (NTRS)

The objective is to develop an optimization procedure for high-speed and civil tilt-rotors by coupling all of the necessary disciplines within a closed-loop optimization procedure. Both simplified and comprehensive analysis codes are used for the aerodynamic analyses. The structural properties are calculated using in-house developed algorithms for both isotropic and composite box beam sections. There are four major objectives of this study. (1) Aerodynamic optimization: The effects of blade aerodynamic characteristics on cruise and hover performance of prop-rotor aircraft are investigated using the classical blade element momentum approach with corrections for the high lift capability of rotors/propellers. (2) Coupled aerodynamic/structures optimization: A multilevel hybrid optimization technique is developed for the design of prop-rotor aircraft. The design problem is decomposed into a level for improved aerodynamics with continuous design variables and a level with discrete variables to investigate composite tailoring. The aerodynamic analysis is based on that developed in objective 1 and the structural analysis is performed using an in-house code which models a composite box beam. The results are compared to both a reference rotor and the optimum rotor found in the purely aerodynamic formulation. (3) Multipoint optimization: The multilevel optimization procedure of objective 2 is extended to a multipoint design problem. Hover, cruise, and take-off are the three flight conditions simultaneously maximized. (4) Coupled rotor/wing optimization: Using the comprehensive rotary wing code CAMRAD, an optimization procedure is developed for the coupled rotor/wing performance in high speed tilt-rotor aircraft. The developed procedure contains design variables which define the rotor and wing planforms.

Chattopadhyay, Aditi; Mccarthy, Thomas R.

1995-01-01

132

Sandstone Formation on the Navajo Loop Trail  

USGS Multimedia Gallery

Views along the Navajo Loop Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandston...

133

Snow on the Navajo Loop Trail  

USGS Multimedia Gallery

Views along the Navajo Loop Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandston...

134

Hoodoo on the Navajo Loop Trail  

USGS Multimedia Gallery

Views along the Navajo Loop Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandston...

135

Cedars on the Navajo Loop Trail  

USGS Multimedia Gallery

Views along the Navajo Loop Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandston...

136

Optimum structure with homogeneous optimum cellular material for maximum fundamental frequency  

Microsoft Academic Search

Ultra-light cellular materials exhibit high stiffness\\/strength to weight ratios and bring opportunity for multifunctional\\u000a performance. One of their potential applications is to build structure with optimum dynamic performance, which is extremely\\u000a important for some structural parts in vehicle engineering and attracts a great attention. This paper presents a two-scale\\u000a optimization method and aims at finding optimal configurations of macro structures

Bin Niu; Jun Yan; Gengdong Cheng

2009-01-01

137

Shape Detectives  

NSDL National Science Digital Library

In this hands-on lesson, students will become Shape Detectives as they identify the two-dimensional shapes, such as triangles, squares and rectangles, needed to build three-dimensional figures including rectangular prisms, square pyramids and cubes. The students will gain an understanding of how two-dimensional shapes are joined together to form three-dimensional figures as well as creating an edible example!

Stan Ward

2012-07-31

138

Optimum flight paths of turbojet aircraft  

NASA Technical Reports Server (NTRS)

The climb of turbojet aircraft is analyzed and discussed including the accelerations. Three particular flight performances are examined: minimum time of climb, climb with minimum fuel consumption, and steepest climb. The theoretical results obtained from a previous study are put in a form that is suitable for application on the following simplifying assumptions: the Mach number is considered an independent variable instead of the velocity; the variations of the airplane mass due to fuel consumption are disregarded; the airplane polar is assumed to be parabolic; the path curvatures and the squares of the path angles are disregarded in the projection of the equation of motion on the normal to the path; lastly, an ideal turbojet with performance independent of the velocity is involved. The optimum Mach number for each flight condition is obtained from the solution of a sixth order equation in which the coefficients are functions of two fundamental parameters: the ratio of minimum drag in level flight to the thrust and the Mach number which represents the flight at constant altitude and maximum lift-drag ratio.

Miele, Angelo

1955-01-01

139

Designing from minimum to optimum functionality  

NASA Astrophysics Data System (ADS)

This paper discusses a multifaceted strategy to link NASA Minimal Functionality Habitable Element (MFHE) requirements to a compatible growth plan; leading forward to evolutionary, deployable habitats including outpost development stages. The discussion begins by reviewing fundamental geometric features inherent in small scale, vertical and horizontal, pressurized module configuration options to characterize applicability to meet stringent MFHE constraints. A proposed scenario to incorporate a vertical core MFHE concept into an expanded architecture to provide continuity of structural form and a logical path from "minimum" to "optimum" design of a habitable module. The paper describes how habitation and logistics accommodations could be pre-integrated into a common Hab/Log Module that serves both habitation and logistics functions. This is offered as a means to reduce unnecessary redundant development costs and to avoid EVA-intensive on-site adaptation and retrofitting requirements for augmented crew capacity. An evolutionary version of the hard shell Hab/Log design would have an expandable middle section to afford larger living and working accommodations. In conclusion, the paper illustrates that a number of cargo missions referenced for NASA's 4.0.0 Lunar Campaign Scenario could be eliminated altogether to expedite progress and reduce budgets. The plan concludes with a vertical growth geometry that provides versatile and efficient site development opportunities using a combination of hard Hab/Log modules and a hybrid expandable "CLAM" (Crew Lunar Accommodations Module) element.

Bannova, Olga; Bell, Larry

2011-04-01

140

Optimum excitation of “enhanced” central transition populations  

NASA Astrophysics Data System (ADS)

Central transition (CT) sensitivity enhancement schemes that transfer polarization from satellites to the CT through selective saturation or inversion of neighboring satellite transitions have provided a welcome improvement for magic-angle spinning spectra of half-integer quadrupole nuclei. While many researchers have investigated and developed different methods of creating enhanced CT populations, here we investigate the conversion of these enhanced CT populations into observable CT coherence. We show a somewhat unexpected result that a conversion pulse length optimized for maximum sensitivity on equilibrium populations may not be optimum for an enhanced (non-equilibrium) polarization. Furthermore, CT enhancements can be lost if excessive rf field strength is used to convert this enhanced polarization into CT coherence. While a maximally enhanced CT signal is expected when using a perfectly selective CT conversion pulse, we have found that significant sensitivity loss can occur when using surprisingly low rf field strengths, even for sites with relatively large quadrupole coupling constants. We have systematically investigated these issues, and present some general guidelines and expectations when optimizing the conversion of enhanced (non-equilibrium) CT populations into observable CT coherence.

Trease, Nicole M.; Dey, Krishna K.; Grandinetti, Philip J.

2009-10-01

141

Optimum deposition conditions of ultrasmooth silver nanolayers  

PubMed Central

Reduction of surface plasmon-polariton losses due to their scattering on metal surface roughness still remains a challenge in the fabrication of plasmonic devices for nanooptics. To achieve smooth silver films, we study the dependence of surface roughness on the evaporation temperature in a physical vapor deposition process. At the deposition temperature range 90 to 500 K, the mismatch of thermal expansion coefficients of Ag, Ge wetting layer, and sapphire substrate does not deteriorate the metal surface. To avoid ice crystal formation on substrates, the working temperature of the whole physical vapor deposition process should exceed that of the sublimation at the evaporation pressure range. At optimum room temperature, the root-mean-square (RMS) surface roughness was successfully reduced to 0.2 nm for a 10-nm Ag layer on sapphire substrate with a 1-nm germanium wetting interlayer. Silver layers of 10- and 30-nm thickness were examined using an atomic force microscope (AFM), X-ray reflectometry (XRR), and two-dimensional X-ray diffraction (XRD2). PACS 63.22.Np Layered systems; 68. Surfaces and interfaces; thin films and nanosystems (structure and nonelectronic properties); 81.07.-b Nanoscale materials and structures: fabrication and characterization PMID:24685115

2014-01-01

142

Climate Feedback Loops  

NSDL National Science Digital Library

This is the seventh of nine lessons in the 'Visualizing and Understanding the Science of Climate Change' website. This lesson addresses climate feedback loops and how these loops help drive and regulate Earth's unique climate system.

King's Centre for Visualization in Science Researchers

143

Optimum three-dimensional atmospheric entry from the analytical solution of Chapman's exact equations  

NASA Technical Reports Server (NTRS)

The general solution for the optimum three-dimensional aerodynamic control of a lifting vehicle entering a planetary atmosphere is developed. A set of dimensionless variables, modified Chapman variables, is introduced. The resulting exact equations of motion, referred to as Chapman's exact equations, have the advantage that they are completely free of the physical characteristics of the vehicle. Furthermore, a completely general lift-drag relationship is used in the derivation. The results obtained apply to any type of vehicle of arbitrary weight, dimensions and shape, having an arbitrary drag polar, and entering any planetary atmosphere. The aerodynamic controls chosen are the lift coefficient and the bank angle. General optimum control laws for these controls are developed. Several earlier particular solutions are shown to be special cases of this general result. Results are valid for both free and constrained terminal position.

Busemann, A.; Vinh, N. X.; Culp, R. D.

1974-01-01

144

Transgressive loop group extensions  

E-print Network

A central extension of the loop group of a Lie group is called transgressive, if it corresponds under transgression to a degree four class in the cohomology of the classifying space of the Lie group. Transgressive loop group extensions are those that can be explored by finite-dimensional, higher-categorical geometry over the Lie group. We show how transgressive central extensions can be characterized in a loop-group theoretical way, in terms of loop fusion and thin homotopy equivariance.

Konrad Waldorf

2015-02-17

145

Strong Shapes  

NSDL National Science Digital Library

Is a square stronger than a triangle? Use tongue depressors to build simple shapes. Then apply a little weight to them and see what happens! This activity comes with useful tips for building the shapes, like how to drill the wood without cracking it, and what drill works best.

2012-06-26

146

Shapes lab  

NSDL National Science Digital Library

This online activity features two simulations demonstrating the comparative strengths of rectangles, arches, and triangles when stress is applied at a point. Simulations offer a simplified version of real life conditions related to the strength and stability of structures. For comparison's sake, each tested shape is of equivalent thickness and has hinged joints. The shapes show load distribution arrows when force is applied. In one simulation, a student selects a shape and initiates a dynamic illustration, providing an explanation of the effect of applying force and demonstrating how the shape can be strengthened. The second simulation shows and explains what results when increasing numbers of elephants are stacked on each of the three shapes. Copyright 2005 Eisenhower National Clearinghouse

WGBH

2001-01-01

147

Implementation of optimum solar electricity generating system  

NASA Astrophysics Data System (ADS)

Under the 10th Malaysian Plan, the government is expecting the renewable energy to contribute approximately 5.5% to the total electricity generation by the year 2015, which amounts to 98MW. One of the initiatives to ensure that the target is achievable was to establish the Sustainable Energy Development Authority of Malaysia. SEDA is given the authority to administer and manage the implementation of the feed-in tariff (FiT) mechanism which is mandated under the Renewable Energy Act 2011. The move to establish SEDA is commendable and the FiT seems to be attractive but there is a need to create awareness on the implementation of the solar electricity generating system (SEGS). In Malaysia, harnessing technologies related to solar energy resources have great potential for implementation. However, the main issue that plagues the implementation of SEGS is the intermittent nature of this source of energy. The availability of sunlight is during the day time, and there is a need for electrical energy storage system, so that there is electricity available during the night time as well. The meteorological condition such as clouds, haze and pollution affects the SEGS as well. The PV based SEGS is seems to be promising electricity generating system that can contribute towards achieving the 5.5% target and will be able to minimize the negative effects of utilizing fossil fuels for electricity generation on the environment. Malaysia is committed to Kyoto Protocol, which emphasizes on fighting global warming by achieving stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. In this paper, the technical aspects of the implementation of optimum SEGS is discussed, especially pertaining to the positioning of the PV panels.

Singh, Balbir Singh Mahinder; Sivapalan, Subarna; Najib, Nurul Syafiqah Mohd; Menon, Pradeep; Karim, Samsul Ariffin A.

2014-10-01

148

Optimum design of uncooled staring infrared camera  

NASA Astrophysics Data System (ADS)

Several models of target acquisition range prediction of the uncooled staring camera and their advantages are proposed in the paper. NVTherm is used to evaluate the modulation transfer function, minimum resolvable temperature difference and target acquisition range. The analysis result shows that the performance of the detector is the key factor to limit the performance of the uncooled staring camera. The target acquisition range of the uncooled infrared camera can be improved by increasing effective focus length (EFL) of optical component, decreasing its F/# or reducing the pixel pitch of the detector. The detection range of 1.09 km can be achieved under the condition of 75 mm EFL and F/0.8. When the EFL changes from 75mm to 150 mm under the condition of F/0.8 and 45?m pixel pitch, the detection range of 2.36 km, recognition range of 0.47 km and identification range of 0.24 km have been gotten. When the pixel pitch is reduced to 35?m, the detection range is 2.59 km. Furthermore, when 2 x 2 microscan is adopted in the camera design, then the pixel pitch will change from 35?m to 17.5?m. Although the infrared camera becomes an optical performance limited system, its performance improves a lot to get the detection range of 2.94 km. The field test shows that the detection range to a 1.7 m x 0.45 m target is 2.2 km under the condition of F/0.8, 150mm EFL and 45 ?m pixel pitch, achieving good matches with the evaluation value of 2.36 km through NVTherm. An optimum uncooled infrared design is achieved using the NVTherm software which shortens the design cycle.

Li, Yingwen; Pan, Debin; Liu, Aidong; Geng, Anbing; Li, Yong; He, Jun

2006-02-01

149

Two novel automatic frequency tracking loops  

NASA Technical Reports Server (NTRS)

Two automatic-frequency-control (AFC) loops are introduced and analyzed in detail. The algorithms are generalizations of the well known cross-product AFC loop with improved performance. The first estimator uses running overlapping discrete Fourier transforms to create a discriminator curve proportional to the frequency estimation error, whereas the second one preprocesses the received data and then uses an extended Kalman filter to estimate the input frequency. The algorithms are tested by computer simulations in a highly dynamic environment at low carrier/noise ratio (CNR). The algorithms are suboptimum tracking schemes with a larger frequency-error variance compared to an optimum strategy, but they offer simplicity of mechanization and a CNR with a very low operating threshold.

Aguirre, Sergio; Hinedi, Sami

1989-01-01

150

Loop functions in thermal QCD  

E-print Network

We discuss divergences of loop functions in thermal QCD and compute perturbatively the Polyakov loop, the Polyakov loop correlator and the cyclic Wilson loop. We show how these functions get mixed under renormalization.

Antonio Vairo

2014-10-16

151

Standardization and optimum structural design by dynamic programming  

Microsoft Academic Search

The paper is concerned with tools for optimum structural design that can taken into account the industrial production of structural elements. Standardization is considered here as the result of minimizing the cost as a function of both element sizes and numbers of identical elements. The optimum value of the design variables obtained by traditional minimum weight (volume) design is taken

E. Vitiello

1977-01-01

152

50 CFR 648.20 - Maximum optimum yield (OYs).  

Code of Federal Regulations, 2010 CFR

... 2010-10-01 2010-10-01 false Maximum optimum yield (OYs). 648.20 Section 648.20 Wildlife and Fisheries...Squid, and Butterfish Fisheries § 648.20 Maximum optimum yield (OYs). The OYs specified pursuant to § 648.21...

2010-10-01

153

Optimum damper locations for a free-free beam  

NASA Technical Reports Server (NTRS)

Algorithms to optimally locate and design dampers for large space structures were developed. The requirements for distributed sensing and actuation in control of structural systems were determined. Mathematical programming was used to solve for optimum damping rate and location. Actuator dynamics were considered to solve for optimum actuator mass.

Horner, G. C.

1981-01-01

154

Performance Based Measurement of Optimum Moisture for Soil Compaction  

E-print Network

Performance Based Measurement of Optimum Moisture for Soil Compaction Bradley Hansen John L. Nieber for a given soil the output period from the DOT600 could be used to check optimum moisture conditions compaction and moisture content #12;DOT600 Volumetric moisture content Dielectric permittivity Calibrated

Minnesota, University of

155

Balanced Boolean Functions with Optimum Algebraic Immunity and High Nonlinearity  

E-print Network

Balanced Boolean Functions with Optimum Algebraic Immunity and High Nonlinearity Xiangyong Zeng of balanced Boolean functions with optimum algebraic immunity are proposed. The cryptographical properties such as balancedness, high algebraic degree, high algebraic immunity, high nonlinearity and good immunity to fast

156

Optimum porous journal bearing ensuring maximum load capacity  

Microsoft Academic Search

The problem of an infinite journal bearing having an isothermal compressible lubricant and a porous bush and ensuring the\\u000a optimum load capacity is solved. The optimum clearance profiles and bush dimensions and position are found for various properties\\u000a of the bush and lubricant supply conditions.

V. I. Grabovskii

2006-01-01

157

An Optimum Design Index of the Bottle with the Vacuum Insulation Structure  

NASA Astrophysics Data System (ADS)

In this paper, we present an optimum design index of the bottle with a vacuum insulation structure. Thinner wall design is required to produce lighter bottles. When the wall thickness is too thin, the bottles crushed external pressure. Therefore it is necessary to provide the optimum design index of the bottle. We showed the factors that may affect on the deformation of bottles. We though the factors are classified into shape and material of the bottle. The factors in shape are length L, diameter D and thickness t of the bottles. And the factors for material are Young's modulus and yield stress. The influence of each factor the critical deformation of bottles was verified by using FEM simulation. The nonlinear structural analysis LS-DYNA of the analytical software was applied. The analytical model simplified the base of the external cylinder is hollow cylinder model with shell element. Material properties for stainless steel (sus304), commercially pure titanium (Ti) and titanium alloy (Ti-6Al-4V). These each analytical model was loaded an external pressure by time steps. The pressure when the analytical model was transformed then was obtained. The result shows that the bottle's strength has the definite relation from its shape and greatly influences the material rigidity.

Horiuchi, Takuya; Tanaka, Tatsuya; Imaida, Yutaka; Nakai, Keiji; Utsumi, Koji

2011-08-01

158

The circular glide dislocation loop lying in an interface  

NASA Astrophysics Data System (ADS)

THE ELASTIC fields of a circular glide dislocation loop lying in the interface separating two isotropic solids are obtained. It is shown that the interface transmits normal tractions in the form of a Dirac delta function. A unified formulation which permits direct calculation for the energy of a variety of interface dislocation configurations is presented. The energy of a loop segment from which the energy of any shape loop may be obtained through integration is derived. Such integration is carried out for a circular loop and comparisons are made with straight dislocations. The force due to line tension is also given, with certain intricacies pointed out.

Salamon, N. J.

1981-02-01

159

Piezoactuator design considering the optimum placement of FGM piezoelectric material  

NASA Astrophysics Data System (ADS)

Functionally Graded Materials (FGMs) possess continuous variation of material properties and are characterized by spatially varying microstructures. Recently, the FGM concept has been explored in piezoelectric materials to improve properties and to increase the lifetime of piezoelectric actuators. Elastic, piezoelectric, and dielectric properties are graded along the thickness of a piezoceramic FGM. Thus, the gradation of piezoceramic properties can influence the performance of piezoactuators, and an optimum gradation can be sought through optimization techniques. However, the design of these FGM piezoceramics are usually limited to simple shapes. An interesting approach to be investigated is the design of FGM piezoelectric mechanisms which essentially can be defined as a FGM structure with complex topology made of piezoelectric and non-piezoelectric material that must generate output displacement and force at a certain specified point of the domain and direction. This can be achieved by using topology optimization method. Thus, in this work, a topology optimization formulation that allows the simultaneous distribution of void and FGM piezoelectric material (made of piezoelectric and non-piezoelectric material) in the design domain, to achieve certain specified actuation movements, will be presented. The method is implemented based on the SIMP material model where fictitious densities are interpolated in each finite element, providing a continuum material distribution in the domain. The optimization algorithm employed is based on sequential linear programming (SLP) and the finite element method is based on the graded finite element concept where the properties change smoothly inside the element. This approach provides a continuum approximation of material distribution, which is appropriate to model FGMs. Some FGM piezoelectric mechanisms were designed to demonstrate the usefulness of the proposed method. Examples are limited to two-dimensional models, due to FGM manufacturing constraints and the fact that most of the applications for such FGM piezoelectric mechanisms are planar devices. An one-dimensional constraint of the material gradation is imposed to provide more realistic designs.

Carbonari, Ronny C.; Nishiwaki, Shinji; Paulino, Glaucio H.; Nelli Silva, Emílio C.

2007-04-01

160

Shape Sorter  

NSDL National Science Digital Library

In this web-based application from Illuminations students must sort shapes based on the categories of the Venn diagram. Users can choose the categories from a drop down menu. The application includes instructions and exploration steps.

2013-01-01

161

Shape Dynamics  

E-print Network

General Relativity can be reformulated as a geometrodynamical theory, called Shape Dynamics, that is not based on spacetime (in particular refoliation) symmetry but on spatial diffeomorphism and local spatial conformal symmetry. This leads to a constraint algebra that is (unlike General Relativity) a Lie algebra, where all local constraints are linear in momenta and may thus be quantized as vector fields on the geometrodynamic configuration space. The Hamiltonian of Shape Dynamics is complicated but admits simple expressions whenever spatial derivatives are negligible.

Tim Koslowski

2011-08-26

162

Skeleton Shapes  

NSDL National Science Digital Library

This activity gives students an opportunity to explore some of the common 3-D shapes and their names and properties. After discussion and an example, it asks students to count the required number of edges and vertices (corners) to build each of 5 given shapes. The Teachers' Notes page includes suggestions for implementation, discussion questions, ideas for extension and support, and a printable recording sheet (pdf).

163

String Shapes  

NSDL National Science Digital Library

In this activity, learners work together to make polygons (many-sided shapes) with string. Learners sit on the floor and hold onto a piece of string slid between their thumbs and index fingers. Learners explore how many different kinds of triangles and other shapes they can make by changing their hand positions. Use this activity to help learners explore polygons including convex and concave polygons and vertices.

Exploratorium

2010-01-01

164

Equilibrium models of coronal loops that involve curvature and buoyancy  

E-print Network

We construct magnetostatic models of coronal loops in which the thermodynamics of the loop is fully consistent with the shape and geometry of the loop. This is achieved by treating the loop as a thin, compact, magnetic fibril that is a small departure from a force-free state. The density along the loop is related to the loop's curvature by requiring that the Lorentz force arising from this deviation is balanced by buoyancy. This equilibrium, coupled with hydrostatic balance and the ideal gas law, then connects the temperature of the loop with the curvature of the loop without resorting to a detailed treatment of heating and cooling. We present two example solutions: one with a spatially invariant magnetic Bond number (the dimensionless ratio of buoyancy to Lorentz forces) and the other with a constant radius of curvature of the loop's axis. We find that the density and temperature profiles are quite sensitive to curvature variations along the loop, even for loops with similar aspect ratios.

Hindman, Bradley W

2013-01-01

165

THE IMPORTANCE OF GEOMETRIC EFFECTS IN CORONAL LOOP MODELS  

SciTech Connect

We systematically investigate the effects of geometrical assumptions in one-dimensional (1D) models of coronal loops. Many investigations of coronal loops have been based on restrictive assumptions, including symmetry in the loop shape and heating profile, and a uniform cross-sectional area. Starting with a solution for a symmetric uniform-area loop with uniform heating, we gradually relax these restrictive assumptions to consider the effects of nonuniform area, nonuniform heating, a nonsymmetric loop shape, and nonsymmetric heating, to show that the character of the solutions can change in important ways. We find that loops with nonuniform cross-sectional area are more likely to experience thermal nonequilibrium, and that they produce significantly enhanced coronal emission, compared with their uniform-area counterparts. We identify a process of incomplete condensation in loops experiencing thermal nonequilibrium during which the coronal parts of loops never fully cool to chromospheric temperatures. These solutions are characterized by persistent siphon flows. Their properties agree with observations (Lionello et al.) and may not suffer from the drawbacks that led Klimchuk et al. to conclude that thermal nonequilibrium is not consistent with observations. We show that our 1D results are qualitatively similar to those seen in a three-dimensional model of an active region. Our results suggest that thermal nonequilibrium may play an important role in the behavior of coronal loops, and that its dismissal by Klimchuk et al., whose model suffered from some of the restrictive assumptions we described, may have been premature.

Mikic, Zoran; Lionello, Roberto; Linker, Jon A. [Predictive Science, Inc., San Diego, CA 92121 (United States); Mok, Yung [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Winebarger, Amy R. [NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States)

2013-08-20

166

March 23, 2008 ICS102: For Loop 1 The for-loop and Nested loops  

E-print Network

March 23, 2008 ICS102: For Loop 1 The for-loop and Nested loops #12;March 23, 2008 ICS102: For Loop, and exit Statements #12;March 23, 2008 ICS102: For Loop 3 - The for Statement Syntax for (Initializing;March 23, 2008 ICS102: For Loop 4 - The for Statement The for statement is most commonly used to step

Adam, Salah

167

Atlas based kinematic optimum design of the Stewart parallel manipulator  

NASA Astrophysics Data System (ADS)

Optimum design is a key approach to make full use of potential advantages of a parallel manipulator. The optimum design of multi-parameter parallel manipulators(more than three design parameters), such as Stewart manipulator, relies on analysis based and algorithm based optimum design methods, which fall to be accurate or intuitive. To solve this problem and achieve both accurate and intuition, atlas based optimum design of a general Stewart parallel manipulator is established, with rational selection of design parameters. Based on the defined spherical usable workspace(SUW), primary kinematic performance indices of the Stewart manipulator, involving workspace and condition number are introduced and analyzed. Then, corresponding performance atlases are drawn with the established non-dimensional design space, and impact of joint distribution angles on the manipulator performance is analyzed and illustrated. At last, an example on atlas based optimum design of the Stewart manipulator is accomplished to illustrate the optimum design process, considering the end-effector posture. Deduced atlases can be flexibly applied to both quantitative and qualitative analysis to get the desired optimal design for the Stewart manipulator with respect to related performance requirements. Besides, the established optimum design method can be further applied to other multi-parameter parallel manipulators.

Shao, Zhufeng; Tang, Xiaoqiang; Wang, Liping; Sun, Dengfeng

2015-01-01

168

Loop-weighted Walk  

E-print Network

Loop-weighted walk with parameter $\\lambda\\geq 0$ is a non-Markovian model of random walks that is related to the loop $O(N)$ model of statistical mechanics. A walk receives weight $\\lambda^{k}$ if it contains $k$ loops; whether this is a reward or punishment for containing loops depends on the value of $\\lambda$. A challenging feature of loop-weighted walk is that it is not purely repulsive, meaning the weight of the future of a walk may either increase or decrease if the past is forgotten. Repulsion is typically an essential property for lace expansion arguments. This article circumvents the lack of repulsion and proves, via the lace expansion, that for any $\\lambda\\geq 0$ loop-weighted walk is diffusive in high dimensions.

Tyler Helmuth

2014-10-12

169

Resonances of coronal loops  

NASA Technical Reports Server (NTRS)

It is pointed out that any theoretical demonstration that the solar corona can be heated by waves requires a demonstration that the required energies can actually be carried from the convection zone to the corona by waves. In addition, it must be shown that the waves can dissipate their energy into heat in the corona. The present investigation is concerned specifically with the heating of closed magnetic structures in the corona, taking into account coronal loops or active region loops. Attention is given to the MHD Alfven wave. It is shown analytically that coronal active region loops can behave much like interference filters. The coronal part of the loop acts like a resonant cavity for Alfven waves. When the resonances are excited, large energy fluxes can be carried into the loop by Alfven waves which are generated in the solar convection zone. It is estimated that the energy fluxes can power the observed loops.

Hollweg, J. V.

1984-01-01

170

Loop Quantum Gravity  

Microsoft Academic Search

The problem of finding the quantum theory of the gravitational field, and\\u000athus understanding what is quantum spacetime, is still open. One of the most\\u000aactive of the current approaches is loop quantum gravity. Loop quantum gravity\\u000ais a mathematically well-defined, non-perturbative and background independent\\u000aquantization of general relativity, with its conventional matter couplings. The\\u000aresearch in loop quantum gravity

Carlo Rovelli

1997-01-01

171

NON-LINEAR FREQUENCY DOMAIN BASED OPTIMUM SHAPE DESIGN FOR UNSTEADY  

E-print Network

in which the flow is inherently unsteady but periodic. Helicopter rotors in forward flight, turbomachinery the unsteady effects that contribute to flutter, buffeting, poor gust and acoustic response, and dynamic stall of a multistage compressor and turbine calculation based on the parallel execution of 750 processors operating 8

Jameson, Antony

172

OPTIMUM SHAPE DESIGN FOR UNSTEADY THREE-DIMENSIONAL VISCOUS FLOWS USING  

E-print Network

important engineering applications in which the flow is inherently unsteady but periodic. Helicopter rotors and acoustic response, and dynamic stall. As yet there have been few efforts in this direction. One estimates for the computational cost of a multistage compressor and turbine calculation based

Jameson, Antony

173

Optimizing coherent anti-Stokes Raman scattering by genetic algorithm controlled pulse shaping  

NASA Astrophysics Data System (ADS)

The hybrid coherent anti-Stokes Raman scattering (CARS) has been successful applied to fast chemical sensitive detections. As the development of femto-second pulse shaping techniques, it is of great interest to find the optimum pulse shapes for CARS. The optimum pulse shapes should minimize the non-resonant four wave mixing (NRFWM) background and maximize the CARS signal. A genetic algorithm (GA) is developed to make a heuristic searching for optimized pulse shapes, which give the best signal the background ratio. The GA is shown to be able to rediscover the hybrid CARS scheme and find optimized pulse shapes for customized applications by itself.

Yang, Wenlong; Sokolov, Alexei

2010-10-01

174

Shape Up!  

NSDL National Science Digital Library

In this activity (pages 8-9), learners investigate the properties of smart materials, which are materials that respond to things that happen around them. Learners train a piece of smart material (Nitinol) to adopt a particular shape. Learners discover that when the Nitinol wire is heated enough, its atoms can move around enough to "reset" its memory. This makes it possible to train the material to have a particular shape. Safety note: Young learners should have adult supervision. Be very careful with the flame and hot wire.

Catherine Jordan

2012-01-01

175

Modeling the optimum conditions for the formation of defect-free CVD graphene on copper melt  

NASA Astrophysics Data System (ADS)

The nucleation and growth of nuclei of graphene (graphene islets) on the surfaces of copper melts during catalytic CVD, i.e., the catalytic decomposition of a gas-phase carbon support, is considered. It is shown that on a copper melt the optimum combination of conditions for the preservation of islets with almost perfect hexagonal shape and the necessary conditions of the CVD-process are reached at the same time. The average distance between the islets and the dimensionless parameter that determines changes in the shape of islets is calculated. The maximum rate of decomposition of the carbon support at which this parameter simultaneously promotes the growth of defect-free islets and the maximum possible rate of growth of the graphene monolayer is determined.

Alekseev, N. I.

2014-09-01

176

Optimum testing of multiple hypotheses in quantum detection theory  

NASA Technical Reports Server (NTRS)

The problem of specifying the optimum quantum detector in multiple hypotheses testing is considered for application to optical communications. The quantum digital detection problem is formulated as a linear programming problem on an infinite-dimensional space. A necessary and sufficient condition is derived by the application of a general duality theorem specifying the optimum detector in terms of a set of linear operator equations and inequalities. Existence of the optimum quantum detector is also established. The optimality of commuting detection operators is discussed in some examples. The structure and performance of the optimal receiver are derived for the quantum detection of narrow-band coherent orthogonal and simplex signals. It is shown that modal photon counting is asymptotically optimum in the limit of a large signaling alphabet and that the capacity goes to infinity in the absence of a bandwidth limitation.

Yuen, H. P.; Kennedy, R. S.; Lax, M.

1975-01-01

177

Piezoactuator Design Considering the Optimum Placement of FGM Piezoelectric Material  

E-print Network

Piezoactuator Design Considering the Optimum Placement of FGM Piezoelectric Material Ronny C of material properties and are characterized by spatially varying microstructures. Recently, the FGM concept of a piezoceramic FGM. Thus, the gradation of piezoceramic properties can influence the performance

Paulino, Glaucio H.

178

Controller architectures for optimum performance in practical active acoustic metamaterials  

E-print Network

Controller architectures for optimum performance in practical active acoustic metamaterials M in the design and production of acoustic metamaterials with physical qualities not seen in naturally occurring of the research into active acoustic metamaterials remains theoretical, therefore to determine whether

Boyer, Edmond

179

On the optimum polarizations of incoherently reflected waves  

NASA Technical Reports Server (NTRS)

The Stokes scattering operator is noted to be the most useful characterization of incoherent scattering in radar imaging; the polarization that would yield an optimum amount of power received from the scatterer is obtained by assuming a knowledge of the Stokes scattering operator instead of the 2x2 scattering matrix with complex elements. It is thereby possible to find the optimum polarizations for the case in which the scatterers can only be fully characterized by their Stokes scattering operator, and the case in which the scatterer can be fully characterized by the complex 2x2 scattering matrix. It is shown that the optimum polarizations reported in the literature form the solution for a subset of a more general class of problems, so that six optimum polarizations can exist for incoherent scattering.

Van Zyl, Jakob J.; Elachi, Charles; Papas, Charles H.

1987-01-01

180

Optimum Transfer Guide: Electronic Media & Communications Why Study Electronic Media?  

E-print Network

Optimum Transfer Guide: Electronic Media & Communications Why Study Electronic Media? The Electronic Media program is de- signed to train story-tellers proficient in convergent media forms who can professional courses in electronic media, visual communications, digital media production, photography

Gelfond, Michael

181

Mean Intensity of Sound in an Auditorium and Optimum Reverberation  

Microsoft Academic Search

The optimum time of reverberation was determined experimentally for the piano, the violin, the violoncello, for bass and soprano voices and human speech in a room of 260 m3. The experimental determinations (1.08-1.14 sec.) give the mean value of 1.11 sec. An earlier investigation in a smaller hall of 126 m3 gave a mean optimum time of Top=1.06 sec. It

Samuel Lifshitz

1926-01-01

182

Optimum scheduling procedure for cogenerating small power producing facilities  

Microsoft Academic Search

A comprehensive model of a small power-producing facility (SPPF) is discussed to determine its optimum operational schedule under utility energy-spot-pricing policies. The model is particularly well suited for SPPFs with both topping and bottoming cogeneration cycles in that the various thermal energy flows are explicitly modeled along with the electrical energy flows. The optimum scheduling algorithm is based on a

H. B. Puttgen; P. R. MacGregor

1989-01-01

183

Optimum Combining in Digital Mobile Radio with Cochannel Interference  

Microsoft Academic Search

This paper studies optimum signal combining for space diversity reception in cellular mobile radio systems. With optimum combining, the signals received by the antennas are weighted and combined to maximize the output signal-to-interference-plus-noise ratio. Thus, with cochannel interference, space diversity is used not only to combat Rayleigh fading of the desired signal (as with maximal ratio combining) but also to

JACK H. WINTERS

1984-01-01

184

Dynamic shape.  

PubMed

Many useful notions of partial order and/or similarity and relatedness of different geometrical features of smooth shapes that occur in psychologically valid descriptions of shape have no equivalents in the usual geometrical shape theories. This is especially true where similarities are noted between objects of different connectivity: in almost all of the present theories the topological type generates the primary categorization. It is argued that such relations find a logical place only in shape theories that involve morphogenesis. Any object can be embedded uniquely in a morphogenetic sequence if one takes resolution as the parameter of the sequence. A theory of measurement is presented that allows one to define surfaces and (boundary-) curves on multiple levels of resolution. The embedding is essentially unique and is generated via a partial differential equation that governs the evolution. A canonical projection connects any high resolution specimen to lower resolution versions. The bifurcation set of the projection generates natural part boundaries. Singularities of the evolution are completely characterized as emergence, accretion and versification processes (involving topological change) and singularities by which inflections (inflection points for curves, parabolic curves for surfaces) are generated. The latter singularities involve a single process for the generation of inflections and three other processes by which the existing inflection structure may be changed. Relations with existing theories in vogue in robotics and AI, as well as in psychophysics are discussed. PMID:3697408

Koenderink, J J; van Doorn, A J

1986-01-01

185

A multiobjective shape optimization study for a subsonic submerged inlet  

NASA Astrophysics Data System (ADS)

The purpose of the present work is to summarize the findings of a multiobjective shape optimization study conducted for a subsonic submerged air vehicle inlet. The objective functions of the optimization problem are distortion and swirl indices defined by the distribution of flow parameters over the exit cross-section of the inlet. The geometry alteration is performed by placing a protrusion in the shape of a fin on the baseline inlet surface. Thus, the design variables of the optimization problem are chosen to be the geometrical parameters defining the fin protrusion; namely fin height, length and incidence angle. The Trade Off (also known as epsilon-constraint) method is employed for finding the Pareto optimal set formed by the nondominated solutions of the feasible design space. Since the flow domain solution is required for every step along the line search, an automated optimization loop is constructed by integrating the optimizer with a surface modeler, a mesh generator and a flow solver through which the flow parameters over the compressor face are computed. In addition, the trade study for fin protrusion, the analyses and the comparison of the baseline and Pareto optimal solutions are presented and observations concerning grid resolution and convergence behaviour are discussed. The results display an irregular and discontinuous Pareto optimal set. Optimum inlet designs are scattered in two regions from which one representative inlet design is chosen and analyzed. As a result, it is concluded that an inlet designer has two options within the framework of this optimization study: an inlet design with high swirl but low distortion or an inlet design with low swirl but higher distortion.

Taskinoglu, Ezgi S.

186

Gravitons and loops  

Microsoft Academic Search

The recently proposed loop representation is used to quantize linearized general relativity. The Fock space of graviton states and its associated algebra of observables are represented in terms of functionals of loops. The ``reality conditions'' are realized by an inner product that is chiral asymmetric, resulting in a chiral-asymmetric ordering for the Hamiltonian, and, in an asymmetric description of the

Abhay Ashtekar; Carlo Rovelli; Lee Smolin

1991-01-01

187

What Controls DNA Looping?  

PubMed Central

The looping of DNA provides a means of communication between sequentially distant genomic sites that operate in tandem to express, copy, and repair the information encoded in the DNA base sequence. The short loops implicated in the expression of bacterial genes suggest that molecular factors other than the naturally stiff double helix are involved in bringing the interacting sites into close spatial proximity. New computational techniques that take direct account of the three-dimensional structures and fluctuations of protein and DNA allow us to examine the likely means of enhancing such communication. Here, we describe the application of these approaches to the looping of a 92 base-pair DNA segment between the headpieces of the tetrameric Escherichia coli Lac repressor protein. The distortions of the double helix induced by a second protein—the nonspecific nucleoid protein HU—increase the computed likelihood of looping by several orders of magnitude over that of DNA alone. Large-scale deformations of the repressor, sequence-dependent features in the DNA loop, and deformability of the DNA operators also enhance looping, although to lesser degrees. The correspondence between the predicted looping propensities and the ease of looping derived from gene-expression and single-molecule measurements lends credence to the derived structural picture. PMID:25167135

Perez, Pamela J.; Clauvelin, Nicolas; Grosner, Michael A.; Colasanti, Andrew V.; Olson, Wilma K.

2014-01-01

188

Geometric Shapes  

NSDL National Science Digital Library

We will be learning the names and properties (# of sides, vertices, parallel sides, etc.) of several different geometric shapes. By now, everybody should know how many sides a square has and be able to recognize a circle. But, do you know how many vertices a parallelogram has, or how many sides to a rhombus? After completing the following exercies, you should be able to answer those questions and many ...

Mr. Hoskins

2005-11-21

189

Loops, Polytopes and Splines  

E-print Network

We uncover an unexpected connection between the physics of loop integrals and the mathematics of spline functions. One loop integrands are Laplace transforms of splines. This clarifies the geometry of the associated loop integrals, since a $n$-node spline has support on an $n$-vertex polyhedral cone. One-loop integrals are integrals of splines on a hyperbolic slice of the cone, yielding polytopes in $AdS$ space. Splines thus give a geometrical counterpart to the rational function identities at the level of the integrand. Spline technology also allows for a clear, simple, algebraic decomposition of higher point loop integrals in lower dimensional kinematics in terms of lower point integrals - e.g. an hexagon integral in 2d kinematics can be written as a sum of scalar boxes. Higher loops can also be understood directly in terms of splines - they map onto spline convolutions, leading to an intriguing representation in terms of hyperbolic simplices integrated over other hyperbolic simplices. We finish with speculations on the interpretation of one-loop integrals as partition functions, inspired by the use of splines in counting points in polytopes.

Miguel F. Paulos

2013-04-22

190

Large lithium loop experience  

SciTech Connect

An engineering design and operating experience of a large, isothermal, lithium-coolant test loop are presented. This liquid metal coolant loop is called the Experimental Lithium System (ELS) and has operated safely and reliably for over 6500 hours through September 1981. The loop is used for full-scale testing of components for the Fusion Materials Irradiation Test (FMIT) Facility. Main system parameters include coolant temperatures to 430/sup 0/C and flow to 0.038 m/sup 3//s (600 gal/min). Performance of the main pump, vacuum system, and control system is discussed. Unique test capabilities of the ELS are also discussed.

Kolowith, R.; Owen, T.J.; Berg, J.D.; Atwood, J.M.

1981-10-01

191

Multiprotein DNA Looping  

NASA Astrophysics Data System (ADS)

DNA looping plays a fundamental role in a wide variety of biological processes, providing the backbone for long range interactions on DNA. Here we develop the first model for DNA looping by an arbitrarily large number of proteins and solve it analytically in the case of identical binding. We uncover a switchlike transition between looped and unlooped phases and identify the key parameters that control this transition. Our results establish the basis for the quantitative understanding of fundamental cellular processes like DNA recombination, gene silencing, and telomere maintenance.

Vilar, Jose M. G.; Saiz, Leonor

2006-06-01

192

Multiprotein DNA looping  

E-print Network

DNA looping plays a fundamental role in a wide variety of biological processes, providing the backbone for long range interactions on DNA. Here we develop the first model for DNA looping by an arbitrarily large number of proteins and solve it analytically in the case of identical binding. We uncover a switch-like transition between looped and unlooped phases and identify the key parameters that control this transition. Our results establish the basis for the quantitative understanding of fundamental cellular processes like DNA recombination, gene silencing, and telomere maintenance.

Jose M. G. Vilar; Leonor Saiz

2006-06-19

193

Closed-loop operation with alternative dewatering technology  

SciTech Connect

The introduction of dewatering devices for closed-loop drilling-fluid circulating systems and reserve pits is derived from technology that has been used in the industrial- and sanitary-waste treatment industries for years. This paper describes an overview of the need for closed-loop systems and provides the optimum design layout, including the fit of a dewatering device, for a drilling location. The introduction of a nonconventional dewatering device, called a screw press/thickener, is reviewed. A case history describing use of this technology in a southern Louisiana inland-marsh-area well is analyzed for the technical and economic viability of operating in a closed-loop mode. Results from this effort include a viable alternative to hauling off waste fluids from drilling sites and the realization that use of this technology can be justified economically.

Halliday, W.S.; Bray, R.P.; Youens, J.W.

1993-03-01

194

Photoconductive CdSe Nanowire Arrays, Serpentines, and Loops Formed by Electrodeposition on Self-Organized Carbon Nanotubes  

E-print Network

Photoconductive CdSe Nanowire Arrays, Serpentines, and Loops Formed by Electrodeposition on Self-density straight arrays, as well as in the shape of serpentines and loops. These nanowires exhibit significant aligned arrays of hundreds of CdSe nanowires, serpentines, and loops. We show that the nanowire Cd

Joselevich, Ernesto

195

Shape Dynamics  

E-print Network

Barbour's formulation of Mach's principle requires a theory of gravity to implement local relativity of clocks, local relativity of rods and spatial covariance. It turns out that relativity of clocks and rods are mutually exclusive. General Relativity implements local relativity of clocks and spatial covariance, but not local relativity of rods. It is the purpose of this contribution to show how Shape Dynamics, a theory that is locally equivalent to General Relativity, implements local relativity of rods and spatial covariance and how a BRST formulation, which I call Doubly General Relativity, implements all of Barbour's principles.

Tim Koslowski

2013-01-09

196

Gummy Shapes  

NSDL National Science Digital Library

In this activity, learners use chemistry to “self-assemble” gummy shapes. Learners discover that self-assembly is a process by which molecules and cells form themselves into functional structures. Learners also learn that self-assembly is used to make nanocapsules that can deliver medication to diseased parts of the body, bypassing healthy parts. This activity is a fun way to talk about the connections between science and cooking, since the gummy capsules produced in this activity are also used in molecular gastronomy.

Sciencenter

2012-01-01

197

Tool Geometry for Friction Stir Welding—Optimum Shoulder Diameter  

NASA Astrophysics Data System (ADS)

The most important geometric parameter in the friction stir welding (FSW) tool design is the shoulder diameter, which is currently estimated by trial and error. Here, we report a combined experimental and theoretical investigation on the influence of shoulder diameter on thermal cycles, peak temperatures, power requirements, and torque during FSW of AA7075-T6. An optimum tool shoulder diameter is identified using a three-dimensional, heat transfer and materials flow model. First, the predictive capability of the model is tested by comparing the computed values of peak temperature, spindle power, and torque requirements for various shoulder diameters against the corresponding experimental data. The change in the values of these variables with shoulder diameter is correctly predicted by the model. The model is then used to identify the optimum tool shoulder diameter that facilitates maximal use of the supplied torque in overcoming interfacial sticking. The tool with optimum shoulder diameter is shown to result in acceptable yield strength (YS) and ductility.

Mehta, M.; Arora, A.; de, A.; Debroy, T.

2011-09-01

198

Deltar beyond one loop  

Microsoft Academic Search

We study the effect of two-loop contributions on the radiative corrections to the muon lifetime in the standard electroweak model. O(alphaalphas) contributions are fully included. We also incorporate all dominant O(alpha2) corrections and identify those logarithms which can be resummed. We present an explicit expression for Deltar which fully exploits our present knowledge of contributions beyond one loop. The phenomenological

Francis Halzen; Bernd A. Kniehl

1991-01-01

199

Hot giant loop holography  

SciTech Connect

We argue that there is a phase transition in the expectation value of the Polyakov loop operator in the large N limit of the high temperature deconfined phase of N=4 Yang-Mills theory on a spatial S{sup 3}. It occurs for the large completely symmetric representation of the SU(N) symmetry group. We speculate that this transition is reflected in the D-branes which are the string theory duals of giant loops.

Grignani, Gianluca [Dipartimento di Fisica, Universita di Perugia, INFN Sezione di Perugia, Via A. Pascoli, 06123 Perugia (Italy); Karczmarek, Joanna L.; Semenoff, Gordon W. [Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1 (Canada)

2010-07-15

200

Thrown for a Loop  

NSDL National Science Digital Library

Students begin to focus on the torque associated with a current carrying loop in a magnetic field. They solve example problems as a class and use diagrams to visualize the vector product. In addition, students learn to calculate the energy of this loop in the magnetic field. Through the associated activity, "Get Your Motor Running," students explore a physical model to gain empirical data and compare it to their calculated data. A homework assignment is also provided as a means of student assessment.

VU Bioengineering RET Program, School of Engineering,

201

Optimum camera placement considering camera specification for security monitoring  

Microsoft Academic Search

Abstract—We,present,an optimum,camera,placement,algo- rithm. We,are motivated,by,the fact that the installation of security cameras,is increasing rapidly. From the system cost point of view, it is desirable to observe all the area of interest by the smallest number,of cameras. We propose,a method,for deciding optimum,camera,placement,automatically,considering,camera specification such as visual distance, visual angle, and resolution. Moreover, to reduce the number of cameras, we divide the

Kenichi Yabuta; Hitoshi Kitazawa

2008-01-01

202

Optimum high temperature strength of two-dimensional nanocomposites  

SciTech Connect

High-temperature nanoindentation was used to reveal nano-layer size effects on the hardness of two-dimensional metallic nanocomposites. We report the existence of a critical layer thickness at which strength achieves optimal thermal stability. Transmission electron microscopy and theoretical bicrystal calculations show that this optimum arises due to a transition from thermally activated glide within the layers to dislocation transmission across the layers. We demonstrate experimentally that the atomic-scale properties of the interfaces profoundly affect this critical transition. The strong implications are that interfaces can be tuned to achieve an optimum in high temperature strength in layered nanocomposite structures.

Monclús, M. A.; Molina-Aldareguía, J. M., E-mail: jon.molina@imdea.org [IMDEA Materials Institute, C/Eric Kandel 2, 28906 Getafe, Madrid (Spain); Zheng, S. J.; Mayeur, J. R.; Beyerlein, I. J.; Mara, N. A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Polcar, T. [Czech Technical University in Prague, Technická 2, Prague 6 (Czech Republic); Llorca, J. [IMDEA Materials Institute, C/Eric Kandel 2, 28906 Getafe, Madrid (Spain); Department of Materials Science, Polytechnic University of Madrid, E. T. S. de Ingenieros de Caminos, 28040 Madrid (Spain)

2013-11-01

203

The Cinderella Loop Project  

NASA Astrophysics Data System (ADS)

The solar loop observed off the northeast limb on 1999 Nov 6 (a.k.a. the Cinderella Loop) is one of the few examples of a loop on the limb observed with all three of the following imaging instruments: TRACE, EIT on SOHO, and SXT on Yohkoh. In this project we investigate the differences that result when examining the Cinderella Loop with one instrument compared with another. For example, what are the loop temperature and emission measure differences that result from the increased special resolution between the two EUV imagers? More specifically, TRACE and EIT have almost identical temperature responses to coronal plasma. Do the observations taken with the higher-resolution TRACE instrument (with 0.5 arcsec pixels) produce statistically different results than those observations taken with the lower-resolution EIT instrument (with 2.6 arcsec pixels)? In addition, the special resolution of EIT and SXT is similar, but the temperature responses of the two instruments are quite different. Are the two instruments even seeing the same loop strands? If they are, what are the temperatures and emission measures that result from the analysis of the two data sets? How do these results change after background subtraction? This presentation will answer these questions. Solar physics research at the University of Memphis is supported by NASA grants NAG5-9783 and NAG5-12096.

Schmelz, J.; Beene, J.; Buchanan, J.; Coyle, T.; Douglass, J.; Nasraoui, K.; O'Connor, J.; Roames, J.; Scott, M.

204

Explaining Warm Coronal Loops  

NASA Technical Reports Server (NTRS)

One of the great mysteries of coronal physics that has come to light in the last few years is the discovery that warn (- 1 INK) coronal loops are much denser than expected for quasi-static equilibrium. Both the excess densities and relatively long lifetimes of the loops can be explained with bundles of unresolved strands that are heated impulsively to very high temperatures. Since neighboring strands are at different stages of cooling, the composite loop bundle is multi-thermal, with the distribution of temperatures depending on the details of the "nanoflare storm." Emission hotter than 2 MK is predicted, but it is not clear that such emission is always observed. We consider two possible explanations for the existence of over-dense warm loops without corresponding hot emission: (1) loops are bundles of nanoflare heated strands, but a significant fraction of the nanoflare energy takes the form of a nonthermal electron beam rather then direct plasma heating; (2) loops are bundles of strands that undergo thermal nonequilibrium that results when steady heating is sufficiently concentrated near the footpoints. We present numerical hydro simulations of both of these possibilities and explore the observational consequences, including the production of hard X-ray emission and absorption by cool material in the corona.

Klimchuk, James A.; Karpen, Judy T.; Patsourakos, Spiros

2008-01-01

205

Holographic Calculations of Euclidean Wilson Loop Correlator in Euclidean anti-de Sitter Space  

E-print Network

The correlation functions of two or more Euclidean Wilson loops of various shapes in Euclidean anti-de Sitter space are computed by considering the minimal area surfaces connecting the loops. The surfaces are parametrized by Riemann theta functions associated with genus three hyperelliptic Riemann surfaces. In the case of two loops, the distance $L$ by which they are separated can be adjusted by continuously varying a specific branch point of the auxiliary Riemann surface. When $L$ is much larger than the characteristic size of the loops, then the loops are approximately regarded as local operators and their correlator as the correlator of two local operators. Similarly, when a loop is very small compared to the size of another loop, the small loop is considered as a local operator corresponding to a light supergravity mode.

Sannah Ziama

2015-01-12

206

Holographic Calculations of Euclidean Wilson Loop Correlator in Euclidean anti-de Sitter Space  

E-print Network

The correlation functions of two or more Euclidean Wilson loops of various shapes in Euclidean anti-de Sitter space are computed by considering the minimal area surfaces connecting the loops. The surfaces are parametrized by Riemann theta functions associated with genus three hyperelliptic Riemann surfaces. In the case of two loops, the distance $L$ by which they are separated can be adjusted by continuously varying a specific branch point of the auxiliary Riemann surface. When $L$ is much larger than the characteristic size of the loops, then the loops are approximately regarded as local operators and their correlator as the correlator of two local operators. Similarly, when a loop is very small compared to the size of another loop, the small loop is considered as a local operator corresponding to a light supergravity mode.

Ziama, Sannah

2015-01-01

207

Prediction of wave shape effects in time-dependent fatigue  

Microsoft Academic Search

The frequency-modified fatigue equations (FMFE) and strain range partitioning (SRP) are examined. In FFME, fatigue damage is intriduced through plastic strain range and frequency of cycle, while wave shape is neglected. In SRP, damage is partitioned among inelastic strain vs life curves for four wave shapes involving balanced and unbalanced loops of ''plasticity'' and ''creep''. The frequency approach is reexamined

1976-01-01

208

Conformational Changes in a Hyperthermostable Glycoside Hydrolase: Enzymatic Activity Is a Consequence of the Loop Dynamics and Protonation Balance  

PubMed Central

Endo-?-1, 4-mannanase from Thermotoga petrophila (TpMan) is a modular hyperthermostable enzyme involved in the degradation of mannan-containing polysaccharides. The degradation of these polysaccharides represents a key step for several industrial applications. Here, as part of a continuing investigation of TpMan, the region corresponding to the GH5 domain (TpManGH5) was characterized as a function of pH and temperature. The results indicated that the enzymatic activity of the TpManGH5 is pH-dependent, with its optimum activity occurring at pH 6. At pH 8, the studies demonstrated that TpManGH5 is a molecule with a nearly spherical tightly packed core displaying negligible flexibility in solution, and with size and shape very similar to crystal structure. However, TpManGH5 experiences an increase in radius of gyration in acidic conditions suggesting expansion of the molecule. Furthermore, at acidic pH values, TpManGH5 showed a less globular shape, probably due to a loop region slightly more expanded and flexible in solution (residues Y88 to A105). In addition, molecular dynamics simulations indicated that conformational changes caused by pH variation did not change the core of the TpManGH5, which means that only the above mentioned loop region presents high degree of fluctuations. The results also suggested that conformational changes of the loop region may facilitate polysaccharide and enzyme interaction. Finally, at pH 6 the results indicated that TpManGH5 is slightly more flexible at 65°C when compared to the same enzyme at 20°C. The biophysical characterization presented here is well correlated with the enzymatic activity and provide new insight into the structural basis for the temperature and pH-dependent activity of the TpManGH5. Also, the data suggest a loop region that provides a starting point for a rational design of biotechnological desired features. PMID:25723179

de Oliveira, Leandro C.; da Silva, Viviam M.; Colussi, Francieli; Cabral, Aline D.; de Oliveira Neto, Mario; Squina, Fabio M.; Garcia, Wanius

2015-01-01

209

Conformational changes in a hyperthermostable glycoside hydrolase: enzymatic activity is a consequence of the loop dynamics and protonation balance.  

PubMed

Endo-?-1, 4-mannanase from Thermotoga petrophila (TpMan) is a modular hyperthermostable enzyme involved in the degradation of mannan-containing polysaccharides. The degradation of these polysaccharides represents a key step for several industrial applications. Here, as part of a continuing investigation of TpMan, the region corresponding to the GH5 domain (TpManGH5) was characterized as a function of pH and temperature. The results indicated that the enzymatic activity of the TpManGH5 is pH-dependent, with its optimum activity occurring at pH 6. At pH 8, the studies demonstrated that TpManGH5 is a molecule with a nearly spherical tightly packed core displaying negligible flexibility in solution, and with size and shape very similar to crystal structure. However, TpManGH5 experiences an increase in radius of gyration in acidic conditions suggesting expansion of the molecule. Furthermore, at acidic pH values, TpManGH5 showed a less globular shape, probably due to a loop region slightly more expanded and flexible in solution (residues Y88 to A105). In addition, molecular dynamics simulations indicated that conformational changes caused by pH variation did not change the core of the TpManGH5, which means that only the above mentioned loop region presents high degree of fluctuations. The results also suggested that conformational changes of the loop region may facilitate polysaccharide and enzyme interaction. Finally, at pH 6 the results indicated that TpManGH5 is slightly more flexible at 65°C when compared to the same enzyme at 20°C. The biophysical characterization presented here is well correlated with the enzymatic activity and provide new insight into the structural basis for the temperature and pH-dependent activity of the TpManGH5. Also, the data suggest a loop region that provides a starting point for a rational design of biotechnological desired features. PMID:25723179

de Oliveira, Leandro C; da Silva, Viviam M; Colussi, Francieli; Cabral, Aline D; de Oliveira Neto, Mario; Squina, Fabio M; Garcia, Wanius

2015-01-01

210

H? loop shaping design for nano-positioning  

Microsoft Academic Search

This article presents the identification and control of a nano-positioning device. The device consists of two stages, which enable two-dimensional positioning. Each stage is actuated by piezo-electric stacks and its motion is sensed by a linear variable differential transformer (LVDT). A 2 × 2 transfer function has been identified to describe the device. In this paper the main limitations to

Abu Sebastian; Srinivasa Salapaka

2003-01-01

211

TRANSACTIONS ON INFORMATION THEORY 245 Optimum Range Resolution of  

E-print Network

in distinguisltmg between different possible target con- figurations. Radar reception systems which perform optimum to provide extra penalties for wrong guesses about the number of targets present. Such a system is capable of simultaneously deciding the number of targets present, their spatial positions (ranges) and their relative

Pratt, Vaughan

212

OPTIMUM PROTEIN LEVELS REQUIRED BY HONEY BEES (HYMENOPTERA, APIDAE)  

E-print Network

Newly emerged honey bees, Apis mellifera L., fed diet containing sucrose plus 23 `% protein from a yeast-whey !%, protein. Wheast (produced by fermentation of cottage cheese whey by yeast) contains 57 % proteinOPTIMUM PROTEIN LEVELS REQUIRED BY HONEY BEES (HYMENOPTERA, APIDAE) TO INITIATE AND MAINTAIN BROOD

Paris-Sud XI, Université de

213

Economic Optimum N Rates for Fertilizing Winter Wheat and Corn  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fertilizer nitrogen (N) costs have increased 100% in the last 4 yrs in the Central Great Plains region (CGPR) of the USA. With that increase in fertilizer cost the region has experienced reduced dryland crop yields due to drought. The question that arises: “is how does optimum fertilizer N rate chan...

214

Optimum Probe Parameters for Entangling Probe in Quantum Key Distribution  

Microsoft Academic Search

For the four-state protocol of quantum key distribution, optimum sets of probe parameters are calculated for the most general unitary probe in which each individual transmitted photon is made to interact with the probe so that the signal and the probe are left in an entangled state, and projective measurement by the probe, made subsequent to projective measurement by the

Howard E. Brandt

2003-01-01

215

The Sequential Generation of $D$Optimum Experimental Designs  

Microsoft Academic Search

It is possible to obtain convergence to a $D$-optimum measure, as defined by Kiefer and Wolfowitz, by successively adding points to a given initial experimental design. The points added correspond to points of maximum variance of the usual least squares estimate of the response mean for the particular regression model at each stage. A new bound is given for the

Henry P. Wynn

1970-01-01

216

Optimum Image Thresholding via Class Uncertainty and Region Homogeneity  

Microsoft Academic Search

Abstract?hresholding is a popular image segmentation method that converts a gray-level image into a binary image. The selection of optimum thresholds has remained a challenge over decades. Besides being a segmentation tool on its own, often it is also a step in many advanced image segmentation techniques in spaces other than the image space. Most of the thresholding methods reported

Punam K. Saha; Jayaram K. Udupa

2001-01-01

217

Optimum Design for Optical Antenna of Space Laser Communication System  

Microsoft Academic Search

A new aspheric surface pre-collimation lenses system for the optical antenna of space laser communication has been optimum designed by optical design software CODE-V. Meanwhile, a Cassegrain antenna with aspheric surface has been designed. By the use of Visual C++, an optical system design software has been set up to analyze optical antenna for the space laser communication system, and

Huajun Yang; Yu Hu; Chenghong Li; Kang Xie; Jin Fu; Hu Wei

2006-01-01

218

Optimum Design of Aerospace Structural Components Using Neural Networks  

NASA Technical Reports Server (NTRS)

The application of artificial neural networks to capture structural design expertise is demonstrated. The principal advantage of a trained neural network is that it requires a trivial computational effort to produce an acceptable new design. For the class of problems addressed, the development of a conventional expert system would be extremely difficult. In the present effort, a structural optimization code with multiple nonlinear programming algorithms and an artificial neural network code NETS were used. A set of optimum designs for a ring and two aircraft wings for static and dynamic constraints were generated using the optimization codes. The optimum design data were processed to obtain input and output pairs, which were used to develop a trained artificial neural network using the code NETS. Optimum designs for new design conditions were predicted using the trained network. Neural net prediction of optimum designs was found to be satisfactory for the majority of the output design parameters. However, results from the present study indicate that caution must be exercised to ensure that all design variables are within selected error bounds.

Berke, L.; Patnaik, S. N.; Murthy, P. L. N.

1993-01-01

219

OPTIMUM ECONOMIC YIELD OF AN INTERNATIONALLY UTILIZED COMMON PROPERTY RESOURCEl  

E-print Network

OPTIMUM ECONOMIC YIELD OF AN INTERNATIONALLY UTILIZED COMMON PROPERTY RESOURCEl LEE G. ANOERSON2 possibility curves is used to describe the open·access equilibrium yield, local maximum economic yields, and a true international maximum economic yield. Finally a complete description of the conditions necessary

220

Searching for an optimum solution to the Bangladesh arsenic crisis  

Microsoft Academic Search

Searching for an optimum solution to the Bangladesh arsenic crisis: Thirty years ago Bangladesh experienced very high levels of infant and child mortality, much of it due to water-borne disease in deltaic conditions where surface water was highly polluted. In what appeared to be one of the great public health achievements, 95% of the population were converted to drinking bacteria-free

Bruce K. Caldwell; John C. Caldwell; S. N. Mitra; Wayne Smith

2003-01-01

221

Optimum Onager: The Classical Mechanics of a Classical Siege Engine  

ERIC Educational Resources Information Center

The onager is a throwing weapon of classical antiquity, familiar to both the ancient Greeks and Romans. Here we analyze the dynamics of onager operation and derive the optimum angle for launching a projectile to its maximum range. There is plenty of scope for further considerations about increasing onager range, and so by thinking about how this…

Denny, Mark

2009-01-01

222

4 Optimum Reception in Additive White Gaussian Noise (AWGN)  

E-print Network

151 4 Optimum Reception in Additive White Gaussian Noise (AWGN) In this chapter, we derive representation of the noise n(t), 0 t T, an infinite number of basis functions are required. But fortunately, only the noise components that lie in the signal space spanned by fk(t), 1 k N, are relevant

Pulfrey, David L.

223

Optimum conditions for composites fiber coating by chemical vapor infiltration  

Microsoft Academic Search

A combined analytical and numerical method is employed to optimize process conditions for composites fiber coating by chemical vapor infiltration. For a first-order deposition reaction, the optimum pressure yielding the maximum deposition rate at a preform center is obtained in closed form and is found to depend only on the activation energy of the deposition reaction, the characteristic pore size,

Stewart K. Griffiths; R. H. Nilson

1998-01-01

224

Optimum position for wells producing at constant wellbore pressure  

SciTech Connect

This paper deals with the determination of the optimum position of several wells, producing at constant different wellbore pressures from a two-dimensional closed-boundary reservoirs, to maximize the cumulative production or the total flow rate. To achieve this objective they authors use an improved version of the analytical solution recently proposed by Rodriguez and Cinco-Ley and an optimization algorithm based on a quasi-Newton procedure with line search. At each iteration the algorithm approximates the negative of the objective function by a cuadratic relation derived from a Taylor series. The improvement of rodriguez and Cinco`s solution is attained in four ways. First, an approximation is obtained, which works better at earlier times (before the boundary dominated period starts) than the previous solution. Second, the infinite sums that are present in the solution are expressed in a condensed form, which is relevant for reducing the computer time when the optimization algorithm is used. Third, the solution is modified to take into account the possibility of having wells starting to produce at different times. This point allows them to deal with the problem of getting the optimum position for an infill drilling program. Last, the solution is extended to include the possibility of changing the value of wellbore pressure or being able to stimulate any of the wells at any time. When the wells are producing at different wellbore pressures it is found that the optimum position is a function of time, otherwise the optimum position is fixed.

Camacho-Velazquez, R.; Rodriguez de la Garza, F. [Univ. Nacional Autonoma de Mexico, Mexico City (Mexico); Galindo-Nava, A. [Inst. Mexicanos del Petroleo, Mexico City (Mexico); [Univ. Nacional de Mexico, Mexico City (Mexico); Prats, M.

1994-12-31

225

February 2005 Determining Optimum Nitrogen Application Rates for Corn  

E-print Network

1 February 2005 Determining Optimum Nitrogen Application Rates for Corn Larry Bundy, Todd Andraski factor affecting the efficiency of N use by corn. It is impera- tive that N application rate recommendations accu- rately predict the amount of N needed to obtain profitable corn yields and minimize N losses

Balser, Teri C.

226

Optimum Treatment Allocation for Dualobjective Clinical Trials with Binary Outcomes  

E-print Network

One common problem in many randomized clinical trials is how to assign patients to several treatment­ tients to various treatment groups in a randomized controlled clinical trial where the primary outcomeOptimum Treatment Allocation for Dual­objective Clinical Trials with Binary Outcomes Wei Zhu, Weng

New York at Stoney Brook, State University of

227

Mercury/Waterfilling: Optimum Power Allocation with Arbitrary Input Constellations  

E-print Network

Mercury/Waterfilling: Optimum Power Allocation with Arbitrary Input Constellations Angel Lozano signalling constellations such as m-PSK or m-QAM are used in lieu of the ideal Gaussian signals. This paper information over parallel channels with arbitrary input constellations. I. INTRODUCTION A problem often

Verdú, Sergio

228

Improved global sea surface temperature analyses using optimum interpolation  

Microsoft Academic Search

The new NOAA operational global sea surface temperature (SST) analysis is described. The analyses use 7 days of in situ (ship and buoy) and satellite SST. These analyses are produced weekly and daily using optimum interpolation (OI) on a 1[degrees] grid. The OI technique requires the specification of data and analysis error statistics. These statistics are derived and show that

Richard W. Reynolds; Thomas M. Smith

1994-01-01

229

Optimum profit model considering production, quality and sale problem  

Microsoft Academic Search

Chen and Liu [‘Procurement Strategies in the Presence of the Spot Market-an Analytical Framework’, Production Planning and Control, 18, 297–309] presented the optimum profit model between the producers and the purchasers for the supply chain system with a pure procurement policy. However, their model with a simple manufacturing cost did not consider the used cost of the customer. In this

Chung-Ho Chen; Chih-Lun Lu

2010-01-01

230

Linear superconducting OGMS system: optimum configuration and performance  

Microsoft Academic Search

The linear superconducting OGMS system is described in terms of an analytical theory, computer simulation and particle stream analysis. The magnetic fields, force densities and equations of particle motion are established to yield the particle trajectories and deflections. These are obtained analytically and numerically, and their examination provides the optimum configuration of the system and the criterion for separation independent

R. Gerber; M. H. Watmough

1989-01-01

231

Optimum Camera Angle for Optic Flow-Based Centering Response  

E-print Network

a camera angle of less than 90 is beneficial. In this paper we present both empirical and analytical of an autonomous helicopter through urban environments [10], and our investigation therefore incor- porates with a simulated autonomous helicopter in a 3D urban canyon. In this context, we define the optimum camera angle

Sukhatme, Gaurav S.

232

Optimum design of Trombe wall system in mediterranean region  

Microsoft Academic Search

Thermal, environment and economic impact of Trombe wall system for residential building in Mediterranean region will be studied in this paper. Moreover, optimum size of this system will be determined by using Life Cycle Cost (LCC) criterion. This will lead to develop an approach for designing the most economic residential building in Mediterranean region.Hour-by-hour energy computer simulations were run with

Samar Jaber; Salman Ajib

2011-01-01

233

Trends in mechanical fasteners. [considering optimum metric fastener system  

NASA Technical Reports Server (NTRS)

Some of the specialty fasteners which are enjoying increasing usage are: thread rolling screws, self drilling and tapping screws, locking screws, tamperproof fasteners, and flanged bolts and nuts. The development of an optimum metric fastener system is recommended for future fastener manufacturing.

Levy, J. B.

1972-01-01

234

Optimum Allocation of Computing Resources in Networked Sensing and Control  

E-print Network

optimum ways of allocating limited com- puting resources for estimation and control of a number of linear and dynamics of the plants. When considering resource allocation for estimation of the plants, we derive the impact of both limited computing and communication resources on estimation and control. I. INTRODUCTION

Murray, Richard M.

235

Robust optimum criteria for tuned mass dampers in fuzzy environments  

Microsoft Academic Search

Tuned mass dampers are widely adopted passive strategies for vibrations mitigation, in the past years extensively investigated to improve the offered protection level in any mechanical systems in which they are installed. Although different mechanical and energetic optimum criteria have been proposed in the last decades by assuming involved parameters as deterministically known, nowadays the need persists to explore more

Giuseppe Carlo Marano; Giuseppe Quaranta

2009-01-01

236

Optimum pattern derivative synthesis in randomly perturbed linear array  

Microsoft Academic Search

The concept of pattern derivative is introduced in an optimal sense in a randomly perturbed linear array with equispaced isotropic elements. The effects of the random variations of weights and element positions on the expectations of the first-order derivative of array space-frequency and power responses are analyzed and employed in optimum weight solutions. Without loss of generality, it is assumed

Byong Kun Chang; Nasir Ahmed

1990-01-01

237

An Application of Calculus: Optimum Parabolic Path Problem  

ERIC Educational Resources Information Center

A practical and technological application of calculus problem is posed to motivate freshman students or junior high school students. A variable coefficient of friction is used in modelling air friction. The case in which the coefficient of friction is a decreasing function of altitude is considered. The optimum parabolic path for a flying object…

Atasever, Merve; Pakdemirli, Mehmet; Yurtsever, Hasan Ali

2009-01-01

238

All-fiber arbitrary and precise pulse spectral shaping  

NASA Astrophysics Data System (ADS)

A fiber-loop-based electro-optic (EO) modulation system is proposed and demonstrated to realize both broadband and high-resolution spectral shaping of laser pulses through direct phase modulation. With this fiber-loop EO modulator, arbitrary spectral shape can be carved and the modulation precision is up to 0.004?nm. The laser spectral bandwidth can be steadily broadened from several MHz to several nanometers through tuning the pulse cycle times and the programmable driving signal. One representative shaped spectrum is presented with a <0.01?nm mismatch to the simulated results, which is used to effectively pre-compensate the pulse spectral distortion during amplification.

Wang, Shiwei; Zheng, Wanguo; Zhao, Lei; Zhu, Qihua; Xu, Jianqiu; Tang, Yulong

2015-04-01

239

Shape Classification Using a Flexible Graph Kernel  

NASA Astrophysics Data System (ADS)

The medial axis being an homotopic transformation, the skeleton of a 2D shape corresponds to a planar graph having one face for each hole of the shape and one node for each junction or extremity of the branches. This graph is non simple since it can be composed of loops and multiple-edges. Within the shape comparison framework, such a graph is usually transformed into a simpler structure such as a tree or a simple graph hereby loosing major information about the shape. In this paper, we propose a graph kernel combining a kernel between bags of trails and a kernel between faces. The trails are defined within the original complex graph and the kernel between trails is enforced by an edition process. The kernel between bags of faces allows to put an emphasis on the holes of the shapes and hence on their genre. The resulting graph kernel is positive semi-definite on the graph domain.

Dupé, François-Xavier; Brun, Luc

240

Improvement of lightweight floating ceiling design with optimum stiffener and isolator locations  

NASA Astrophysics Data System (ADS)

In this paper, a new design concept of a lightweight floating ceiling with a special arrangement of stiffener beams and isolators is proposed to enhance vibration isolation performance. The key design parameters of resonant frequency of bending and mode shape factor on vibration transmission are determined with some simple formulae. Structural vibrations and noise radiation are evaluated with finite element models (FEM) for various designs. The optimum ceiling designs are applied in a studio, and field measurements with reliable frequency range of 30-400 Hz are conducted to confirm the theoretical results. The analyses ascertain that four design features ensure the optimum vibration isolation performance: the stiffener beams must be installed at the nodal line of fundamental bending resonance of the plate; smaller panels should be applied instead of a large panel covering the whole area of the ceiling, and joints should be free; the isolators should be placed at the nodal point of the bending mode of the plate; and the fundamental bending resonance frequency must not match the modal critical frequency. The proposed stiffened wooden panel design achieved a noise and vibration reduction of 20 dB in the frequency range of 40-100 Hz, and was better than the performance of a concrete floating floor.

Hui, C. K.; Ng, C. F.

2009-11-01

241

Optimum electrostatic force control for fabricating a hybrid UV-curable aspheric lens  

NASA Astrophysics Data System (ADS)

The purpose of this paper is to use a hybrid structure and the electrostatic force to fabricate aspheric lenses with high optical transmittance (95% at 405 nm). The hybrid structure is composed of Norland Optical Adhesive 63 (NOA63) (refractive index: 1.5802 at 405 nm) and BK-7 glass (refractive index: 1.5302). OSLO (Optics Software for Layout and Optimization) and CFD (Computational Fluid Dynamics) software packages were used to simulate the electric field gradient between the top and bottom electrodes and to produce the optimum bottom electrode design. Different electrode designs were also tested in order to optimize the morphology of the lens profile. The resulting lens profiles have clear apertures of approximately 0.92 mm with maximum shape errors of less than 0.18% and the spot size of the fabricated aspheric lenses can be controlled to approximately 0.504 µm. This technology can be used as a generic approach to fabricate lenses for applications in various micro-optical systems. Partially based on the following paper, orally presented at IEEE NEMS 2010 conference: Hung K-Y, Chang L-W, Tseng F-G and Hang N T M 2010 Optimum electrostatic-force control for fabricating a hybrid UV-curable aspheric lens 5th IEEE Int. Conf. on Nano/Micro Engineered and Molecular Systems (Xiamen, China, 20-23 January 2010).

Hung, Kuo-Yung; Chang, Liang-Wei; Tseng, Fan-Gang; Chiou, Jin-Chern; Chiu, Yi

2010-07-01

242

Fine Structures and Overlying Loops of Confined Solar Flares  

NASA Astrophysics Data System (ADS)

Using the H? observations from the New Vacuum Solar Telescope at the Fuxian Solar Observatory, we focus on the fine structures of three confined flares and the issue why all the three flares are confined instead of eruptive. All the three confined flares take place successively at the same location and have similar morphologies, so can be termed homologous confined flares. In the simultaneous images obtained by the Solar Dynamics Observatory, many large-scale coronal loops above the confined flares are clearly observed in multi-wavelengths. At the pre-flare stage, two dipoles emerge near the negative sunspot, and the dipolar patches are connected by small loops appearing as arch-shaped H? fibrils. There exists a reconnection between the small loops, and thus the H? fibrils change their configuration. The reconnection also occurs between a set of emerging H? fibrils and a set of pre-existing large loops, which are rooted in the negative sunspot, a nearby positive patch, and some remote positive faculae, forming a typical three-legged structure. During the flare processes, the overlying loops, some of which are tracked by activated dark materials, do not break out. These direct observations may illustrate the physical mechanism of confined flares, i.e., magnetic reconnection between the emerging loops and the pre-existing loops triggers flares and the overlying loops prevent the flares from being eruptive.

Yang, Shuhong; Zhang, Jun; Xiang, Yongyuan

2014-10-01

243

The Cinderella loop project  

NASA Astrophysics Data System (ADS)

The solar loop that formed off the northeast limb of the Sun on 1999 November 6 (a.k.a. the Cinderella loop) is one of the few examples of a loop on the limb observed with all three of the following imaging instruments: the Transition Region and Coronal Explorer (TRACE), the SOHO Extreme-ultraviolet Imaging Telescope (EIT), and the Yohkoh Soft X-ray Telescope (SXT). In this project we investigate the temperature differences that result when examining the Cinderella loop with one instrument compared with another. For example, what temperature differences result from the increased spatial resolution between the two EUV imagers? More specifically, given that TRACE and EIT have almost identical temperature response to coronal plasma, does the different spatial resolution of TRACE (with 0.5? pixels) and EIT (with 2.6? pixels) produce statistically different results? We find that the answer is no, and that our results do not change after background subtraction. In addition, the spatial resolution of EIT and SXT is similar, but the temperature responses of the two instruments are quite different. The two instruments do not seem to be viewing the same loop strands, and the plasma temperature differences are significant.

Schmelz, J. T.; Beene, J.; Coyle, T.; Douglass, J.; Nasraoui, K.; O'Connor, J.; Roames, J.; Scott, M.

2006-01-01

244

Tracking performance of unbalanced QPSK demodulators. I - Biphase Costas loop with passive arm filters  

NASA Technical Reports Server (NTRS)

Unbalanced quadriphase-shift-keying (QPSK) is an attractive means for transmitting two digital data streams which in general have different average powers, data rates, and data formats. Previous analyses of the tracking performance of Costas loop demodulators of unbalanced QPSK have accounted only for the filtering effect produced by the loop's two arm filters on the equivalent additive noise perturbing the loop. When the bandwidth of these filters is selected on the basis of the order of the data rate, as is typical of optimum Costas loop design, the filtering degradations of the data modulations themselves and the cross-modulation noise produced by their multiplication in the loop often cannot be neglected. The purpose of this paper is to incorporate these additional filtering effects into the analysis. Many of the results obtained herein are in the form of closed-form expressions which can easily be evaluated numerically for design and performance prediction purposes.

Simon, M. K.; Alem, W. K.

1978-01-01

245

Superordinate Shape Classification Using Natural Shape Statistics  

ERIC Educational Resources Information Center

This paper investigates the classification of shapes into broad natural categories such as "animal" or "leaf". We asked whether such coarse classifications can be achieved by a simple statistical classification of the shape skeleton. We surveyed databases of natural shapes, extracting shape skeletons and tabulating their parameters within each…

Wilder, John; Feldman, Jacob; Singh, Manish

2011-01-01

246

Geometric Parameterization and Multiobjective Shape Optimization of Convective Periodic Channels  

Microsoft Academic Search

In this article we describe a general procedure for the geometric parameterization and multiobjective shape optimization of periodic wavy channels, representative of the repeating module of an ample variety of heat exchangers. The two objectives considered are the maximization of heat transfer rate and the minimization of friction factor. Since there is no single optimum to be found, we use

E. Nobile; F. Pinto; G. Rizzetto

2006-01-01

247

Shape Comparison Using Perturbing Shape Registration  

PubMed Central

Shape registration is often involved in computing statistical differences between groups of shapes, which is a key aspect of morphometric study. The results of shape difference are found to be sensitive to registration, i.e., different registration methods lead to varied results. This raises the question of how to improve the reliability of registration procedures. This paper proposes a perturbation scheme, which perturbs registrations by feeding them with different resampled shape groups, and then aggregates the resulting shape differences. Experiments are conducted using three typical registration algorithms on both synthetic and biomedical shapes, where more reliable inter-group shape differences are found under the proposed scheme. PMID:20386618

Jiang, Yifeng; Edmiston, Erin; Wang, Fei; Blumberg, Hilary P.; Staib, Lawrence H.; Papademetris, Xenophon

2010-01-01

248

Physical Meaning of the Optimum Measurement Process in Quantum Detection Theory  

NASA Technical Reports Server (NTRS)

The optimum measurement processes are represented as the optimum detection operators in the quantum detection theory. The error probability by the optimum detection operators goes beyond the standard quantum limit automatically. However the optimum detection operators are given by pure mathematical descriptions. In order to realize a communication system overcoming the standard quantum limit, we try to give the physical meaning of the optimum detection operators.

Osaki, Masao; Kozuka, Haruhisa; Hirota, Osamu

1996-01-01

249

Closed Loop Welding Controller for Manufacturing Process  

NASA Astrophysics Data System (ADS)

The aim of this paper is to investigate on the closed loop welding controller of a rapid manufacturing Shaped Metal Deposition (SMD) process. SMD was developed and patented by Rolls-Royce in order to produce mechanical parts directly from a CAD model. A simplified SMD plant has been set up in order to investigate the welding dynamics and parameters and to develop a SMD automatic controller. On the basis of the experience acquired, some basic control laws have been developed, and a closed loop controller has been implemented. This controller permits to find and to maintain the process stability condition, so that the final process results totally automatic. The control is performed adjusting the welding conditions on the basis of arc voltage information obtained from the welding machine during the deposition. The experimental results reported confirm the validity of the proposed strategy.

Bonaccorso, F.; Bruno, C.; Cantelli, L.; Longo, D.; Muscato, G.; Rapisarda, S.

2011-12-01

250

The Anderson Current Loop  

NASA Technical Reports Server (NTRS)

Four-wire-probe concept applied to electrical-resistance transducers. Anderson current loop is excitation-and-signal-conditioning circuit suitable for use with strain gauges, resistance thermometers, and other electrical-resistance transducers mounted in harsh environments. Used as alternative to Wheatstone bridge. Simplifies signal-conditioning problem, enabling precise measurement of small changes in resistance of transducer. Eliminates some uncertainties in Wheatstone-bridge resistance-change measurements in flight research. Current loop configuration makes effects of lead-wire and contact resistances insignificantly small. Also provides output voltage that varies linearly with change in gauge resistance, and does so at double sensitivity of Wheatstone bridge.

Anderson, Karl F.

1994-01-01

251

Loop Quantum Gravity  

E-print Network

This article presents an "in-a-nutshell" yet self-contained introductory review on loop quantum gravity (LQG) -- a background-independent, nonperturbative approach to a consistent quantum theory of gravity. Instead of rigorous and systematic derivations, it aims to provide a general picture of LQG, placing emphasis on the fundamental ideas and their significance. The canonical formulation of LQG, as the central topic of the article, is presented in a logically orderly fashion with moderate details, while the spin foam theory, black hole thermodynamics, and loop quantum cosmology are covered briefly. Current directions and open issues are also summarized.

Dah-Wei Chiou

2014-12-14

252

Measuring the self-attraction and rigidity of fibers from their loops, with application to  

E-print Network

Measuring the self-attraction and rigidity of fibers from their loops, with application to sickle of sickle hemoglobin fibers. We calculate the attraction in the stem that stabilises the loop shape fluctuations. Our estimate of the lateral inter-fiber attraction for sickle hemoglobin fibers is in the range 9

Turner, Matthew

253

EXPERIMENTS AND INELASTIC ANALYSIS OF THE LOOP TACK TEST FOR PRESSURE-SENSITIVE ADHESIVES  

Microsoft Academic Search

The loop tack test is studied experimentally and numerically using a model system. The ends of a steel strip are clamped together, giving a teardrop shape, and the loop is pushed downward onto an acrylic foam tape and then pulled upward off the tape. In the finite element analysis, the strip is represented by beam elements and a bilinear elastic–plastic

Youngjin Woo; Raymond H. Plaut; David A. Dillard; Stacy L. Coulthard

2004-01-01

254

Tumbling flow in loop-scavenged two-stroke engines  

Microsoft Academic Search

A multidimensional calculation procedure is used to investigate the flow in loop-scavenged two-stroke engine with curved cylinder heads. Five different cylinder heads are considered. The curvature of cylinder head increases from case 1 to case 4. In case 5 the head curvature is further increased, but it is shaped in the radially outer region. Calculations reveal that a tumbling vortex

Yeng-Yung Tsui; Hong-Ping Cheng

1995-01-01

255

Two Bridges Formation on the Navajo Loop Trail  

USGS Multimedia Gallery

Views along the Navajo Loop Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandston...

256

Design of helicopter rotor blades for optimum dynamic characteristics  

NASA Technical Reports Server (NTRS)

The possibilities and limitations of tailoring blade mass and stiffness distributions to give an optimum blade design in terms of weight, inertia, and dynamic characteristics are discussed. The extent that changes in mass of stiffness distribution can be used to place rotor frequencies at desired locations is determined. Theoretical limits to the amount of frequency shift are established. Realistic constraints on blade properties based on weight, mass, moment of inertia, size, strength, and stability are formulated. The extent that the hub loads can be minimized by proper choice of E1 distribution, and the minimum hub loads which can be approximated by a design for a given set of natural frequencies are determined. Aerodynamic couplings that might affect the optimum blade design, and the relative effectiveness of mass and stiffness distribution on the optimization procedure are investigated.

Peters, D. A.; Ko, T.; Korn, A. E.; Rossow, M. P.

1983-01-01

257

Design of helicopter rotor blades for optimum dynamic characteristics  

NASA Technical Reports Server (NTRS)

The possibilities and the limitations of tailoring blade mass and stiffness distributions to give an optimum blade design in terms of weight, inertia, and dynamic characteristics are investigated. Changes in mass or stiffness distribution used to place rotor frequencies at desired locations are determined. Theoretical limits to the amount of frequency shift are established. Realistic constraints on blade properties based on weight, mass moment of inertia size, strength, and stability are formulated. The extent hub loads can be minimized by proper choice of EL distribution is determined. Configurations that are simple enough to yield clear, fundamental insights into the structural mechanisms but which are sufficiently complex to result in a realistic result for an optimum rotor blade are emphasized.

Peters, D. A.; Ko, T.; Korn, A. E.; Rossow, M. P.

1982-01-01

258

General solutions of optimum problems in nonstationary flight  

NASA Technical Reports Server (NTRS)

A general method concerning optimum problems in nonstationary flight is developed and discussed. Best flight techniques are determined for the following conditions: climb with minimum time, climb with minimum fuel consumption, steepest climb, descending and gliding flight with maximum time or with maximum distance. Optimum distributions of speed with altitude are derived assuming constant airplane weight and neglecting curvatures and squares of path inclination in the projection of the equation of motion on the normal to the flight path. The results of this paper differ from the well-known results obtained by neglecting accelerations with one exception, namely the case of gliding with maximum range. The paper is concluded with criticisms and remarks concerning the physical nature of the solutions and their usefulness for practical applications.

Miele, Angelo

1955-01-01

259

Implementation of an optimum profile guidance system on STOLAND  

NASA Technical Reports Server (NTRS)

The implementation on the STOLAND airborne digital computer of an optimum profile guidance system for the augmentor wing jet STOL research aircraft is described. Major tasks were to implement the guidance and control logic to airborne computer software and to integrate the module with the existing STOLAND navigation, display, and autopilot routines. The optimum profile guidance system comprises an algorithm for synthesizing mimimum fuel trajectories for a wide range of starting positions in the terminal area and a control law for flying the aircraft automatically along the trajectory. The avionics software developed is described along with a FORTRAN program that was constructed to reflect the modular nature and algorthms implemented in the avionics software.

Flanagan, P. F.

1978-01-01

260

Closing the Loop Sampler.  

ERIC Educational Resources Information Center

Closing the Loop (CTL) is a science curriculum designed to introduce students to integrated waste management through awareness. This document presents five lesson plans focusing on developing an understanding of natural resources, solid wastes, conservation, and the life of landfills. Contents include: (1) "What Are Natural Resources?"; (2)…

California Integrated Waste Management Board, Sacramento.

261

Closing the Assessment Loop  

ERIC Educational Resources Information Center

Accreditors, speakers at assessment conferences, and campus leaders all decry the fact that too few faculty are closing the loop--that is, studying assessment findings to see what improvements might be suggested and taking the appropriate steps to make them. This is difficult enough with locally developed measures; adding the need to interpret…

Banta, Trudy W.; Blaich, Charles

2011-01-01

262

Temporal Resolution [Loop Search  

E-print Network

perform the following steps. 1. Transform A into SNF, giving a set of clauses AS. 2. Perform step Logic [TEMPORAL RESOLUTION: LOOP SEARCH] ­ p.2/24 #12;Merged SNF To apply the temporal resolution rule, it is often convenient to combine one or more step clauses. Consequently, a variant on SNF called merged-SNF

Fisher, Michael

263

Loop heat pipes  

Microsoft Academic Search

Loop heat pipes (LHPs) are two-phase heat-transfer devices with capillary pumping of a working fluid. They possess all the main advantages of conventional heat pipes, but owing to the original design and special properties of the capillary structure are capable of transferring heat efficiency for distances up to several meters at any orientation in the gravity field, or to several

Yu. F. Maydanik

2005-01-01

264

NETL - Chemical Looping Reactor  

ScienceCinema

NETL's Chemical Looping Reactor unit is a high-temperature integrated CLC process with extensive instrumentation to improve computational simulations. A non-reacting test unit is also used to study solids flow at ambient temperature. The CLR unit circulates approximately 1,000 pounds per hour at temperatures around 1,800 degrees Fahrenheit.

None

2014-06-26

265

NETL - Chemical Looping Reactor  

SciTech Connect

NETL's Chemical Looping Reactor unit is a high-temperature integrated CLC process with extensive instrumentation to improve computational simulations. A non-reacting test unit is also used to study solids flow at ambient temperature. The CLR unit circulates approximately 1,000 pounds per hour at temperatures around 1,800 degrees Fahrenheit.

None

2013-07-24

266

A criterion for optimum adhesion applied to fibre reinforced composites  

Microsoft Academic Search

The effects of physical adhesion on the mechanical properties of a composite structure are examined in this work. A criterion\\u000a for optimum adhesion between matrix and reinforcing fibres is proposed based on maximizing the wetting tension. It is shown\\u000a that the maximum wetting tension criterion best fulfils two important requirements for a strong interface:(i) the physical\\u000a interactions at the molecular

M. CONNOR; J.-E BIDAUX; J.-A. E MANSON

1997-01-01

267

Optimum Probe Parameters for Entangling Probe in Quantum Key Distribution  

Microsoft Academic Search

For the four-state protocol of quantum key distribution, optimum sets of\\u000aprobe parameters are calculated for the most general unitary probe in which\\u000aeach individual transmitted photon is made to interact with the probe so that\\u000athe signal and the probe are left in an entangled state, and projective\\u000ameasurement by the probe, made subsequent to projective measurement by the

Howard E. Brandt

2003-01-01

268

Sand deserts during glacial maximum and climatic optimum  

Microsoft Academic Search

THE past 20,000 yr have witnessed tremendous climatic changes, a glacial maximum at about 18,000 yr BP and a climatic optimum centred on about 6,000 yr BP, both of which mark extreme situations for the Quaternary. This paper attempts to show that active sand dunes were extensive 18,000 yr ago. Conversely, it seems that sand dunes were generally dormant 6,000

Michael Sarnthein

1978-01-01

269

Pressure swing adsorption process: Performance optimum and adsorbent selection  

Microsoft Academic Search

Simulation results for an adsorptive gas separation process are presented. A feed gas mixture containing 25% methane and 75% hydrogen at a pressure of 20 atm is separated by a four-bed, nine-step pressure swing adsorption process to produce high purity hydrogen. The optimum operating conditions for producing maximum net product are identified. It is shown that improving mass-transfer characteristics of

Ravi Kumar

1994-01-01

270

Optimum operation of improved wave-power converter  

Microsoft Academic Search

An improved version of the previously proposed resonance-tuned absorber of ocean-wave power is presented. The absorber utilises a machine to control its movement in an optimum way relative to the time evolvement of the incident wave. As a result, the improved absorber becomes theoretically as efficient in non-harmonic waves as the resonance-tuned absorber is in harmonic waves. Assuming waves and

K. Budal; J. Falnes

1977-01-01

271

Identification of airfoil characteristics for optimum wind turbine performance / b  

E-print Network

and optimum segment power output, various values of drag were included in the analysis. During the optimization process the maximum segment power value is determined for a given value of the lift coefficient and the effect of drag is assessed after... required to acheive maximum segment power output. It is therefore necessary to determine this lift deficiency effect on turbine performance. This will allow for better airfoil design or selection, since the effect on turbine performance for various...

Miller, Leonard Scott

1983-01-01

272

Towards AC-induced optimum control of dynamical localization  

E-print Network

It is shown that optimum control of dynamical localization (quantum suppression of classical diffusion) in the context of ultracold atoms in periodically shaken optical lattices subjected to time-periodic forces having equidistant zeros depends on the \\textit{impulse} transmitted by the external force over half-period rather than on the force amplitude. This result provides a useful principle for optimally controlling dynamical localization in general periodic systems, which is capable of experimental realization.

F. Revuelta; R. Chacón; F. Borondo

2014-09-15

273

The Population of Small Comets: Optimum Techniques for Detection  

NASA Technical Reports Server (NTRS)

The goals of this project were: (1) to present evidence to the scientific community for the importance of the small comet population and (2) to develop techniques for optimum detection in order to characterize the population. The work has been carried out by D. Schleicher (Lowell Observatory), M. A'Hearn and Y. Fernandez (University of Maryland), I.A.F. Stewart, C. Randall, and J. Brandt (University of Colorado).

Schleicher, D.; AHearn, M.; Stewart, I. A. F.; Randall, C.; Brandt, J.

1999-01-01

274

On the optimum conditions in an isenthalpic liquefaction process  

Microsoft Academic Search

Summary  Two criteria for optimum conditions in isenthalpic liquefaction processes are discussed. The first criterion treated is that\\u000a of maximum yield of liquid per unit of gas compressed. This well-known criterion leads to conditions corresponding to the\\u000a inversion curve. The second criterion discussed is that of maximum yield per unit of energy expended. This criterion is evaluated\\u000a and it is shown

A. Wegener Sleeswijk

1957-01-01

275

Optimum protein-excipient interactions using molecular docking simulations  

E-print Network

Summer 2013 – Spring 2014 | 69 Optimum protein-excipient interactions using molecular docking simulations Haider Sulaiman Tarar THE PROBLEM Protein drugs have a tendency to aggregate, which adversely affects their shelf life and delivery... as a stable drug formulation. Of the top 100 drugs by U.S. sales in the fourth quarter of 2012, 28 were protein drugs or other biologics (source: IMS Health, http://www.imshealth.com). More than 100 genuine, and similar numbers of modified...

Tarar, Haider

2014-04-01

276

Optimum Design of Steel Frames via Harmony Search Algorithm  

Microsoft Academic Search

A harmony search algorithm is presented for optimum design of planar and space steel frames in this chapter. Harmony search\\u000a (HS) is a meta-heuristic search method. It bases on the analogy between natural musical performance process and searching\\u000a the solutions to optimization problems. The design algorithm aims to obtain minimum weight frames by selecting a standard\\u000a set of steel sections.

S. O. Degertekin

277

Optimum design of steel frames using harmony search algorithm  

Microsoft Academic Search

In this article, harmony search algorithm was developed for optimum design of steel frames. Harmony search is a meta-heuristic\\u000a search method that has been developed recently. It bases on the analogy between the performance process of natural music and\\u000a searching for solutions to optimization problems. The objective of the design algorithm is to obtain minimum weight frames\\u000a by selecting suitable

S. O. Degertekin

2008-01-01

278

Automated optimum design of wing structures. Deterministic and probabilistic approaches  

NASA Technical Reports Server (NTRS)

The automated optimum design of airplane wing structures subjected to multiple behavior constraints is described. The structural mass of the wing is considered the objective function. The maximum stress, wing tip deflection, root angle of attack, and flutter velocity during the pull up maneuver (static load), the natural frequencies of the wing structure, and the stresses induced in the wing structure due to landing and gust loads are suitably constrained. Both deterministic and probabilistic approaches are used for finding the stresses induced in the airplane wing structure due to landing and gust loads. A wing design is represented by a uniform beam with a cross section in the form of a hollow symmetric double wedge. The airfoil thickness and chord length are the design variables, and a graphical procedure is used to find the optimum solutions. A supersonic wing design is represented by finite elements. The thicknesses of the skin and the web and the cross sectional areas of the flanges are the design variables, and nonlinear programming techniques are used to find the optimum solution.

Rao, S. S.

1982-01-01

279

Optimum combining of residual carrier array signals in correlated noises  

NASA Technical Reports Server (NTRS)

An array feed combining system for the recovery of signal-to-noise ratio (SNR) loss due to antenna reflector deformation has been implemented and is currently being evaluated on the Jet Propulsion Laboratory 34-m DSS-13 antenna. The current signal-combining system operates under the assumption that the white Gaussian noise processes in the received signals from different array elements are mutually uncorrelated. However, experimental data at DSS 13 indicate that these noise processes are indeed mutually correlated. The objective of this work is to develop a signal-combining system optimized to account for the mutual correlations between these noise processes. The set of optimum combining weight coefficients that maximizes the combined signal SNR in the correlated noises environment is determined. These optimum weights depend on unknown signal and noise covariance parameters. A maximum-likelihood approach is developed to estimate these unknown parameters to obtain estimates of the optimum weight coefficients based on residual carrier signal samples. The actual combined signal SNR using the estimated weight coefficients is derived and shown to converge to the maximum achievable SNR as the number of signal samples increases. These results are also verified by simulation. A numerical example shows a significant improvement in SNR performance can be obtained, especially when the amount of correlation increases.

Liang, R.; Suen, P. H.; Tan, H. H.

1996-01-01

280

Optimum Damping in a Non-Linear Base Isolation System  

NASA Astrophysics Data System (ADS)

Optimum isolation damping for minimum acceleration of a base-isolated structure subjected to earthquake ground excitation is investigated. The stochastic model of the El-Centro1940 earthquake, which preserves the non-stationary evolution of amplitude and frequency content of ground motion, is used as an earthquake excitation. The base isolated structure consists of a linear flexible shear type multi-storey building supported on a base isolation system. The resilient-friction base isolator (R-FBI) is considered as an isolation system. The non-stationary stochastic response of the system is obtained by the time dependent equivalent linearization technique as the force-deformation of the R-FBI system is non-linear. The optimum damping of the R-FBI system is obtained under important parametric variations; i.e., the coefficient of friction of the R-FBI system, the period and damping of the superstructure; the effective period of base isolation. The criterion selected for optimality is the minimization of the top floor root mean square (r.m.s.) acceleration. It is shown that the above parameters have significant effects on optimum isolation damping.

Jangid, R. S.

1996-02-01

281

Optimum Combining of Residual Carrier Array Signals in Correlated Noises  

NASA Technical Reports Server (NTRS)

An array feed combining system for the recovery of signal-to-noise ratio (SNR) loss due to antenna reflector deformation has been implemented and is currently being evaluated on the Jet Propulsion Laboratory 34-m DSS-13 antenna. The current signal-combining system operates under the assumption that the white Gaussian noise processes in the received signals from different array elements are mutually uncorrelated. However, experimental data at DSS 13 indicate that these noise processes are indeed mutually correlated. The objective of this work is to develop a signal-combining system optimized to account for the mutual correlations between these noise processes. The set of optimum combining weight coefficients that maximizes the combined signal SNR in the correlated noises environment is determined. These optimum weights depend on unknown signal and noise covariance parameters. A maximum-likelihood approach is developed to estimate these unknown parameters to obtain estimates of the optimum weight coefficients based on residual carrier signal samples. The actual combined signal SNR using the estimated weight coefficients is derived and shown to converge to the maximum achievable SNR as the number of signal samples increases. These results are also verified by simulation. A numerical example shows a significant improvement in SNR performance can be obtained, especially when the amount of correlation increases.

Tan, H. H.; Liang, R.; Suen, P.-H.

1996-01-01

282

Optimum design of structures subject to general periodic loads  

NASA Technical Reports Server (NTRS)

A simplified version of Icerman's problem regarding the design of structures subject to a single harmonic load is discussed. The nature of the restrictive conditions that must be placed on the design space in order to ensure an analytic optimum are discussed in detail. Icerman's problem is then extended to include multiple forcing functions with different driving frequencies. And the conditions that now must be placed upon the design space to ensure an analytic optimum are again discussed. An important finding is that all solutions to the optimality condition (analytic stationary design) are local optima, but the global optimum may well be non-analytic. The more general problem of distributing the fixed mass of a linear elastic structure subject to general periodic loads in order to minimize some measure of the steady state deflection is also considered. This response is explicitly expressed in terms of Green's functional and the abstract operators defining the structure. The optimality criterion is derived by differentiating the response with respect to the design parameters. The theory is applicable to finite element as well as distributed parameter models.

Reiss, Robert; Qian, B.

1989-01-01

283

Shapes and Geometry  

NSDL National Science Digital Library

Today we will learn more about shapes. We will also have a chance to create new shapes out of the shapes we receive! First, click on Sorting. Sort the different shapes by size, color, or shape. You will have to decide which way the shapes are being sorted each time. Sort shapes five times. Next, create some Quadrilaterals. This Quadrilateral can move as you click the vertex with the mouse and move it. ...

Ms. Holmgren

2006-10-27

284

SHAPES and PATTERNS  

NSDL National Science Digital Library

Students will be working with extending a pattern, making shapes and comparing shapes! MATH IS FUN and lets have some fun with patterns! Click to begin: Making Patterns Now that we have worked with patterns, lets work on our shapes. The world is made up of shapes everywhere! Click to begin:Comparing Shapes to the Real World You have now seen that the world is full of shapes, lets make some shapes of ...

Ms. Simpson

2007-10-29

285

Design of packed bed reactors: guides to catalyst shape, size, and loading selection  

Microsoft Academic Search

The engineering design of packed bed based unit operations is very much influenced by the structure of the packing matrix, which in turn is governed by the shape, dimensions and the loading of the constituent particles. For, say, reactor applications, optimum design of catalyst pellet in terms of shape configuration, internal pores and available surface area can promote catalytic activity

S Afandizadeh; E. A Foumeny

2001-01-01

286

Constellation Shaping for Bit-Interleaved Coded APSK Dr. Matthew C. Valenti, Xingyu Xiang  

E-print Network

Constellation Shaping for Bit-Interleaved Coded APSK Dr. Matthew C. Valenti, Xingyu Xiang Lane in our paper APSK (Amplitude phase-shift keying) Included in DVB-S2 (second generation of the Digital shaping (nonuniform APSK modulation) Capacity Analysis Optimum parameters modulation) Simulation

Valenti, Matthew C.

287

Optimum rocket propulsion for energy-limited transfer  

NASA Technical Reports Server (NTRS)

In order to effect large-scale return of extraterrestrial resources to Earth orbit, it is desirable to optimize the propulsion system to maximize the mass of payload returned per unit energy expended. This optimization problem is different from the conventional rocket propulsion optimization. A rocket propulsion system consists of an energy source plus reaction mass. In a conventional chemical rocket, the energy source and the reaction mass are the same. For the transportation system required, however, the best system performance is achieved if the reaction mass used is from a locally available source. In general, the energy source and the reaction mass will be separate. One such rocket system is the nuclear thermal rocket, in which the energy source is a reactor and the reaction mass a fluid which is heated by the reactor and exhausted. Another energy-limited rocket system is the hydrogen/oxygen rocket where H2/O2 fuel is produced by electrolysis of water using a solar array or a nuclear reactor. The problem is to choose the optimum specific impulse (or equivalently exhaust velocity) to minimize the amount of energy required to produce a given mission delta-v in the payload. The somewhat surprising result is that the optimum specific impulse is not the maximum possible value, but is proportional to the mission delta-v. In general terms, at the beginning of the mission it is optimum to use a very low specific impulse and expend a lot of reaction mass, since this is the most energy efficient way to transfer momentum. However, as the mission progresses, it becomes important to minimize the amount of reaction mass expelled, since energy is wasted moving the reaction mass. Thus, the optimum specific impulse will increase with the mission delta-v. Optimum I(sub sp) is derived for maximum payload return per energy expended for both the case of fixed and variable I(sub sp) engines. Sample missions analyzed include return of water payloads from the moons of Mars and of Saturn.

Zuppero, Anthony; Landis, Geoffrey A.

1991-01-01

288

Loop Heat Pipes and Capillary Pumped Loops: An Applications Perspective  

NASA Technical Reports Server (NTRS)

Capillary pumped loops (CPLS) and loop heat pipes (LHPS) are versatile two-phase heat transfer devices which have recently gained increasing acceptance in space applications. Both systems work based on the same principles and have very similar designs. Nevertheless, some differences exist in the construction of the evaporator and the hydro-accumulator, and these differences lead to very distinct operating characteristics for each loop. This paper presents comparisons of the two loops from an applications perspective, and addresses their impact on spacecraft design, integration, and test. Some technical challenges and issues for both loops are also addressed.

Butler, Dan; Ku, Jentung; Swanson, Theodore; Obenschain, Arthur F. (Technical Monitor)

2001-01-01

289

Calibration of circular loop antennas  

Microsoft Academic Search

The calibration of a measuring loop antenna means assigning an antenna factor K for each frequency in the entire measurement band. Such a loop antenna factor can be found either by calculating the impedances of the loop, or by using a well-defined standard magnetic field of a transmitting antenna. For both methods, it is necessary to obtain an accurate relation

Aydin Aykan

1998-01-01

290

Scanning Polyhedra with DO Loops  

Microsoft Academic Search

Supercompilers perform complex program transformations which often result in new loop bounds. This paper shows that, under the usual assumptions in automatic parallelization, most transformations on loop nests can be expressed as affine transformations on integer sets de ned by polyhedra and that the new loop bounds can be computed with algorithms using Fourier's pairwise elimination method although it is

Corinne Ancourt; François Irigoin

1991-01-01

291

Colors and Shapes  

NSDL National Science Digital Library

How do you name things by color and shape? Lets learn about shapes and colors! 1. Watch this Color Video 2. Play this Color Game 3. Complete this Color Page 4. Watch this Shape Video 5. Watch this Shape Video2 6. Play this Shape Game 7. ...

Ms.Campbell

2012-04-04

292

Optimum Design of High Speed Prop-Rotors  

NASA Technical Reports Server (NTRS)

The objective of this research is to develop optimization procedures to provide design trends in high speed prop-rotors. The necessary disciplinary couplings are all considered within a closed loop optimization process. The procedures involve the consideration of blade aeroelastic, aerodynamic performance, structural and dynamic design requirements. Further, since the design involves consideration of several different objectives, multiobjective function formulation techniques are developed.

Chattopadhyay, Aditi

1992-01-01

293

The Cinderella Loop Project  

NASA Astrophysics Data System (ADS)

On 1999 Nov 6 at 02:30 UT, a solar loop (dubbed Cinderella) on the northeast limb was simultaneously observed by TRACE, EIT on SOHO, and SXT on Yohkoh. This project investigates differences among the data sets from the three instruments. For example, EIT and TRACE have nearly identical temperature responses, but does the high resolution TRACE imager (0.5 arcsec pixels) produce results that match those from the lower resolution EIT imager (2.6 arcsec pixels)? Furthermore, EIT and SXT have similar spatial resolutions, but their temperature responses are much farther apart. Do these two instruments observe the same structures within the loop, and if so, how do their temperature and emissions measures compare? What are the effects of background subtraction on all three data sets? This presentation will address these questions. Solar physics research at the University of Memphis is supported by NASA grants NAG5-9783 and NAG5-12096.

O'Connor, J.; Coyle, T.; Douglass, J.; Schmelz, J. T.

2004-05-01

294

Getting Your Loops Straight  

NSDL National Science Digital Library

This article introduces a special issue on the study of biochemical signaling pathways. Complicated biochemical signaling pathways regulate the function of living cells. Such regulatory networks often have â??downstreamâ? components that provide input to components that act earlier in a pathway, creating feedback loops. These feedback loops have the potential to greatly alter the properties of a pathway and how it responds to stimuli. To fully understand these regulatory systems and exploit their vast potential as targets of therapeutic strategies, we need quantitative information on the flow of signals through a pathway and on the timing and location of signaling events within cells. The papers assembled in this special issue and in the companion issue of Science Signaling highlight recent progress in tackling these challenges.

L. Bryan Ray (AAAS; )

2008-10-17

295

Screening actuator locations for static shape control  

NASA Technical Reports Server (NTRS)

Correction of shape distortion due to zero-mean normally distributed errors in structural sizes which are random variables is examined. A bound on the maximum improvement in the expected value of the root-mean-square shape error is obtained. The shape correction associated with the optimal actuators is also characterized. An actuator effectiveness index is developed and shown to be helpful in screening actuator locations in the structure. The results are specialized to a simple form for truss structures composed of nominally identical members. The bound and effectiveness index are tested on a 55-m radiometer antenna truss structure. It is found that previously obtained results for optimum actuators had a performance close to the bound obtained here. Furthermore, the actuators associated with the optimum design are shown to have high effectiveness indices. Since only a small fraction of truss elements tend to have high effectiveness indices, the proposed screening procedure can greatly reduce the number of truss members that need to be considered as actuator sites.

Haftka, Raphael T.

1990-01-01

296

Chemical Looping Combustion Kinetics  

SciTech Connect

One of the most promising methods of capturing CO{sub 2} emitted by coal-fired power plants for subsequent sequestration is chemical looping combustion (CLC). A powdered metal oxide such as NiO transfers oxygen directly to a fuel in a fuel reactor at high temperatures with no air present. Heat, water, and CO{sub 2} are released, and after H{sub 2}O condensation the CO{sub 2} (undiluted by N{sub 2}) is ready for sequestration, whereas the nickel metal is ready for reoxidation in the air reactor. In principle, these processes can be repeated endlessly with the original nickel metal/nickel oxide participating in a loop that admits fuel and rejects ash, heat, and water. Our project accumulated kinetic rate data at high temperatures and elevated pressures for the metal oxide reduction step and for the metal reoxidation step. These data will be used in computational modeling of CLC on the laboratory scale and presumably later on the plant scale. The oxygen carrier on which the research at Utah is focused is CuO/Cu{sub 2}O rather than nickel oxide because the copper system lends itself to use with solid fuels in an alternative to CLC called 'chemical looping with oxygen uncoupling' (CLOU).

Edward Eyring; Gabor Konya

2009-03-31

297

Cosmic string loop microlensing  

NASA Astrophysics Data System (ADS)

Cosmic superstring loops within the galaxy microlens background point sources lying close to the observer-string line of sight. For suitable alignments, multiple paths coexist and the (achromatic) flux enhancement is a factor of two. We explore this unique type of lensing by numerically solving for geodesics that extend from source to observer as they pass near an oscillating string. We characterize the duration of the flux doubling and the scale of the image splitting. We probe and confirm the existence of a variety of fundamental effects predicted from previous analyses of the static infinite straight string: the deficit angle, the Kaiser-Stebbins effect, and the scale of the impact parameter required to produce microlensing. Our quantitative results for dynamical loops vary by O(1) factors with respect to estimates based on infinite straight strings for a given impact parameter. A number of new features are identified in the computed microlensing solutions. Our results suggest that optical microlensing can offer a new and potentially powerful methodology for searches for superstring loop relics of the inflationary era.

Bloomfield, Jolyon K.; Chernoff, David F.

2014-06-01

298

Loops of Jupiter  

NASA Astrophysics Data System (ADS)

Professor Antoni Opolski was actively interested in astronomy after his retirement in 1983. He especially liked to study the works of the famous astronomer Copernicus getting inspiration for his own work. Opolski started his work on planetary loops in 2011 continuing it to the end of 2012 . During this period calculations, drawings, tables, and basic descriptions of all the planets of the Solar System were created with the use of a piece of paper and a pencil only. In 2011 Antoni Opolski asked us to help him in editing the manuscript and preparing it for publication. We have been honored having the opportunity to work on articles on planetary loops with Antoni Opolski in his house for several months. In the middle of 2012 the detailed material on Jupiter was ready. However, professor Opolski improved the article by smoothing the text and preparing new, better drawings. Finally the article ''Loops of Jupiter'', written by the 99- year old astronomer, was published in the year of his 100th birthday.

Opolski, Antoni

2014-12-01

299

Optimum Thread Rolling Process That Improves SCC Resistance  

SciTech Connect

Accelerated testing in environments aggressive for the specific material have shown that fastener threads that are rolled after strengthening heat treatments have improved resistance to SCC initiation. For example, intergranular SCC was produced in one day when machined (cut) threads of high strength steel (ASTM A193 B-7 and A354 Grade 8) were exposed to an aggressive aqueous environment containing 8 weight % boiling ammonium nitrate and stressed to about 40% of the steel's yield strength (120 ksi, 827 MPa). In similar testing conditions, fasteners that had threads rolled before heat-treatment (quench and temper) had similar susceptibility to SCC. However, threads rolled after strengthening, exhibited no SCC after a week of exposure, even when stressed to 100% of the B-7 alloy yield strength. Similarly, intergranular SCC was produced in less than one day when machined (cut) threads of nickel-base alloys (X-750 and aged 625) were exposed to an aggressive 750 F doped steam environment (containing 100 ppm of chloride, fluoride, sulfate, nitrate and a controlled hydrogen overpressure) and stressed to about 80% of the alloy yield strength (117 ksi, 807 MPa). In similar testing conditions, threads rolled after strengthening exhibited no SCC after 50 days of exposure. This beneficial effect of the optimum thread rolling process (i.e., threads rolled after strengthening) is due to the retention of large residual compressive stresses in the thread roots (notches) which mitigate the applied notch tensile stresses resulting from joint design pre-loads. use of these material specific aggressive environments can provide an accelerated test to verify that threads were produced by the optimum thread rolling process. These tests could support fastener acceptance criteria or failure analysis of fasteners with unknown or uncertain manufacturing processes. The optimum process effects may not always be detected by more conventional methods (e.g., metallography or hardness testing).

A.R. Kephart

2001-10-29

300

Initial stages of misfit stress relaxation by rectangular prismatic dislocation loops in composite nanostructures  

NASA Astrophysics Data System (ADS)

Theoretical models are proposed for describing the initial stages of misfit stress relaxation in bulk and hollow core-shell nanoparticles and nanowires, and in planar bi- and trinanolayers through generation of rectangular prismatic dislocation loops at the inner and outer interfaces. We obtain the changes in the total energy of the system due to the appearance of dislocation loops and calculate the critical conditions of their formation. We also determine the most profitable shape of the loops and the preferred places of their generation. Finally, we choose the nanostructures which are the most stable against dislocation loop generation.

Gutkin, M. Yu; Smirnov, A. M.

2014-10-01

301

Some results on optimum allocation for sampling on two occasions  

E-print Network

are exact for any sample size, (c) unbiased variance estimators can be obtained. However, it may be slightly less efficient than the regression esti- ms. tcr Des Raj investigated the optimum percent to be matched by mini- mizing the variance subject... to fixed cost, assuming the cost per matohed unit is the same as the cost per unmatched unit (i. e. , d 1) and m + u n (i. e. , R n). Des Raj has shown that the loss in efficiency of the difference estimator over the regression estimator is very small...

Shimizugawa, Hisako

1966-01-01

302

Optimum value of original events on the PEPT technique  

SciTech Connect

Do Positron emission particle tracking (PEPT) has been used to track the motion of a single radioactively labeled tracer particle within a bed of similar particles. In this paper, the effect of the original event fraction on the results precise in two experiments has been reviewed. Results showed that the algorithm can no longer distinguish some corrupt trajectories, in addition to; further iteration reduces the statistical significance of the sample without improving its quality. Results show that the optimum value of trajectories depends on the type of experiment.

Sadremomtaz, Alireza; Taherparvar, Payvand [University of Guilan, P.O. Box 3489, Rasht, Guilan (Iran, Islamic Republic of)

2011-12-26

303

Modeling and optimum time performance for concurrent processing  

NASA Technical Reports Server (NTRS)

The development of a new graph theoretic model for describing the relation between a decomposed algorithm and its execution in a data flow environment is presented. Called ATAMM, the model consists of a set of Petri net marked graphs useful for representing decision-free algorithms having large-grained, computationally complex primitive operations. Performance time measures which determine computing speed and throughput capacity are defined, and the ATAMM model is used to develop lower bounds for these times. A concurrent processing operating strategy for achieving optimum time performance is presented and illustrated by example.

Mielke, Roland R.; Stoughton, John W.; Som, Sukhamoy

1988-01-01

304

Design optimum frac jobs using virtual intelligence techniques  

NASA Astrophysics Data System (ADS)

Designing optimal frac jobs is a complex and time-consuming process. It usually involves the use of a two- or three-dimensional computer model. For the computer models to perform as intended, a wealth of input data is required. The input data includes wellbore configuration and reservoir characteristics such as porosity, permeability, stress and thickness profiles of the pay layers as well as the overburden layers. Among other essential information required for the design process is fracturing fluid type and volume, proppant type and volume, injection rate, proppant concentration and frac job schedule. Some of the parameters such as fluid and proppant types have discrete possible choices. Other parameters such as fluid and proppant volume, on the other hand, assume values from within a range of minimum and maximum values. A potential frac design for a particular pay zone is a combination of all of these parameters. Finding the optimum combination is not a trivial process. It usually requires an experienced engineer and a considerable amount of time to tune the parameters in order to achieve desirable outcome. This paper introduces a new methodology that integrates two virtual intelligence techniques, namely, artificial neural networks and genetic algorithms to automate and simplify the optimum frac job design process. This methodology requires little input from the engineer beyond the reservoir characterizations and wellbore configuration. The software tool that has been developed based on this methodology uses the reservoir characteristics and an optimization criteria indicated by the engineer, for example a certain propped frac length, and provides the detail of the optimum frac design that will result in the specified criteria. An ensemble of neural networks is trained to mimic the two- or three-dimensional frac simulator. Once successfully trained, these networks are capable of providing instantaneous results in response to any set of input parameters. These networks will be used as the fitness function for a genetic algorithm routine that will search for the best combination of the design parameters for the frac job. The genetic algorithm will search through the entire solution space and identify the optimal combination of parameters to be used in the design process. Considering the complexity of this task this methodology converges relatively fast, providing the engineer with several near-optimum scenarios for the frac job design. These scenarios, which can be achieved in just a minute or two, can be valuable initial points for the engineer to start his/her design job and save him/her hours of runs on the simulator.

Mohaghegh, Shahab; Popa, Andrei; Ameri, Sam

2000-10-01

305

Coupled dual loop absorption heat pump  

DOEpatents

A coupled dual loop absorption system which utilizes two separate complete loops. Each individual loop operates at three temperatures and two pressures. This low temperature loop absorber and condenser are thermally coupled to the high temperature loop evaporator, and the high temperature loop condenser and absorber are thermally coupled to the low temperature generator.

Sarkisian, Paul H. (Watertown, MA); Reimann, Robert C. (Lafayette, NY); Biermann, Wendell J. (Fayetteville, NY)

1985-01-01

306

Optimum quantisers for a Gaussian input probability density and for the magnitude-error distortion measure  

NASA Technical Reports Server (NTRS)

The parameters of non-uniform and uniform quantizers up to ten bits of quantization, optimum for a Gaussian input probability and for the magnitude-error distortion criterion are computed. Optimum quantizers must be understood as quantizers with minimum distortion. The numerical method used for the optimization converges relatively rapidly. The comparison between optimum non-uniform quantizers and optimum uniform quantizers is made.

Demaret, J. C.

1975-01-01

307

Optimum Aerodynamic Design Using the Navier–Stokes Equations  

Microsoft Academic Search

:   This paper describes the formulation of optimization techniques based on control theory for aerodynamic shape design in viscous\\u000a compressible flow, modeled by the Navier–Stokes equations. It extends previous work on optimization for inviscid flow. The\\u000a theory is applied to a system defined by the partial differential equations of the flow, with the boundary shape acting as\\u000a the control. The

A. Jameson; L. Martinelli; N. A. Pierce

1998-01-01

308

On the Role of Intrinsic and Extrinsic Forces in Early Cardiac S-looping  

PubMed Central

Background Looping is a crucial phase during heart development when the initially straight heart tube is transformed into a shape that more closely resembles the mature heart. Although the genetic and biochemical pathways of cardiac looping are well-studied, the biophysical mechanisms that actually effect the looping process remain poorly understood. Using a combined experimental (chick embryo) and computational (finite element modeling) approach, we study the forces driving early s-looping when the primitive ventricle moves to its definitive position inferior to the common atrium. Results New results from our study indicate that the primitive heart has no intrinsic ability to form an s-loop and that extrinsic forces are necessary to effect early s-looping. They support previous studies that established an important role for cervical flexure in causing early cardiac s-looping. Our results also show that forces applied by the splanchnopleure cannot be ignored during early s-looping and shed light on the role of cardiac jelly. Using available experimental data and computer modeling, we successfully developed and tested a hypothesis for the force mechanisms driving s-loop formation. Conclusions Forces external to the primitive heart tube are necessary in the later stages of cardiac looping. Experimental and model results support our proposed hypothesis for forces driving early s-looping. PMID:23553909

Ramasubramanian, Ashok; Chu-LaGraff, Quynh B.; Buma, Takashi; Chico, Kevin T.; Carnes, Meagan E.; Burnett, Kyra R.; Bradner, Sarah A.; Gordon, Shaun S.

2014-01-01

309

Optimum dietary protein requirement of Malaysian mahseer (Tor tambroides) fingerling.  

PubMed

The optimum dietary protein requirement of the Malaysian mahseer (Tor tambroides) fingerlings was determined in this study. In this completely randomized designed experiment, formulated diets of five levels of dietary protein (30, 35, 40, 45 and 50%) were tested on the T. tambroides fingerlings (initial body weight of 5.85 +/- 0.40 g), reared in aquarium fitted with a biofiltering system. The fingerlings were fed twice daily at 5% of biomass. The fingerling body weight and total length was taken at every two weeks. Mortality was recorded daily. The dietary protein had significant effects on the body weight gain and Specific Growth Rate (SGR) of the fingerlings. The body weight gain and SGR of fingerlings fed with the diet with the dietary protein level of 40% was significantly higher (p<0.05) than that of 30, 35 and 50%. The feed conversion ratio of the 40% dietary protein was the significantly lowest at 2.19 +/- 0.163. The dietary protein level of 40% was the most optimum for T. tambroides fingerlings. PMID:21870647

Misieng, Josephine Dorin; Kamarudin, Mohd Salleh; Musa, Mazlinda

2011-02-01

310

Investigation of Various Essential Factors for Optimum Infrared Thermography  

PubMed Central

ABSTRACT We investigated various essential factors for optimum infrared thermography for cattle clinics. The effect of various factors on the detection of surface temperature was investigated in an experimental room with a fixed ambient temperature using a square positioned on a wall. Various factors of animal objects were examined using cattle to determine the relationships among presence of hair, body surface temperature, surface temperature of the eyeball, the highest temperature of the eye circle, rectum temperature and ambient temperature. Also, the surface temperature of the flank at different time points after eating was examined. The best conditions of thermography for cattle clinics were determined and were as follows: (1) The distance between a thermal camera and an object should be fixed, and the camera should be set within a 45-degree angle with respect to the objects using the optimum focal length. (2) Factors that affect the camera temperature, such as extreme cold or heat, direct sunshine, high humidity and wind, should be avoided. (3) For the comparison of thermographs, imaging should be performed under identical conditions. If this is not achievable, hairless parts should be used. PMID:23759714

OKADA, Keiji; TAKEMURA, Kei; SATO, Shigeru

2013-01-01

311

Optimized conical shaped charge design using the SCAP (Shaped Charge Analysis Program) code  

SciTech Connect

The Shaped Charge Analysis Program (SCAP) is used to analytically model and optimize the design of Conical Shaped Charges (CSC). A variety of existing CSCs are initially modeled with the SCAP code and the predicted jet tip velocities, jet penetrations, and optimum standoffs are compared to previously published experimental results. The CSCs vary in size from 0.69 inch (1.75 cm) to 9.125 inch (23.18 cm) conical liner inside diameter. Two liner materials (copper and steel) and several explosives (Octol, Comp B, PBX-9501) are included in the CSCs modeled. The target material was mild steel. A parametric study was conducted using the SCAP code to obtain the optimum design for a 3.86 inch (9.8 cm) CSC. The variables optimized in this study included the CSC apex angle, conical liner thickness, explosive height, optimum standoff, tamper/confinement thickness, and explosive width. The non-dimensionalized jet penetration to diameter ratio versus the above parameters are graphically presented. 12 refs., 10 figs., 7 tabs.

Vigil, M.G.

1988-09-01

312

Beam shaping for holographic techniques  

NASA Astrophysics Data System (ADS)

Uniform intensity of laser radiation is very important in holographic and interferometry technologies, therefore transformation of typical Gaussian distribution of a TEM00 laser to flat-top (top hat) is an actual technical task, it is solved by applying beam shaping optics. Holography and interferometry have specific requirements to a uniform laser beam, most important of them are flatness of phase front and extended depth of field. There are different refractive and diffractive beam shaping approaches used in laser industrial and scientific applications, but only few of them are capable to fulfil the optimum conditions for beam quality demanding holography and interferometry. We suggest applying refractive field mapping beam shapers piShaper, which operational principle presumes almost lossless transformation of Gaussian to flat-top beam with flatness of output wavefront, conserving of beam consistency, providing collimated low divergent output beam, high transmittance, extended depth of field, negligible wave aberration, and achromatic design provides capability to work with several lasers with different wavelengths simultaneously. This approach is used in SLM-based technologies of Computer Generated Holography, Dot-Matrix mastering of security holograms, holographic data storage, holographic projection, lithography, interferometric recording of Volume Bragg Gratings. High optical quality of resulting flat-top beam allows applying additional optical components to vary beam size and shape, thus adapting an optical system to requirements of a particular application. This paper will describe design basics of refractive beam shapers and optical layouts of their applying in holographic systems. Examples of real implementations and experimental results will be presented as well.

Laskin, Alexander; Laskin, Vadim; Ostrun, Aleksei

2014-09-01

313

The Gulf Loop Current  

NSDL National Science Digital Library

Students conduct experiments and explore wind driven currents, determining patterns of current flow in a body of water. They participate in a relay where they blow a Styrofoam peanut or cotton ball across the classroom floor. They explore the motion of Styrofoam pieces that are floating in a clear pie pan of water simulating the Gulf Loop, and compare their pie pan model with a map of the currents. Students will map the trip of several different types of beach debris as it travels to the Texas coast.

Pam Stryker

2010-01-01

314

Capillary Pumped Loop Modeler  

NASA Technical Reports Server (NTRS)

Capillary Pumped Loop (CPL) Modeler computer program is amalgamation of software that mathematically models performance of CPL system and its environment. Two-phase heat-transport device capable of transferring heat loads efficiently over large distance with little temperature differential. Utilizes surface-tension forces established in fine-pore capillary wick to circulate working fluid, requiring no external pumpling power. Predicts steady-state or quasi-steady behavior of CPL embedded in spacecraft or other thermal environment. Also predicts location of liquid/vapor interface in each condenser. Written in VAX/VMS FORTAN 77.

Ku, Jentung; Itkin, Elliot; Schweickart, Russell B.; Ottenstein, Laura

1990-01-01

315

Closing the loop.  

PubMed

Closed-loop algorithms can be found in every aspect of everyday modern life. Automation and control are used constantly to provide safety and to improve quality of life. Closed-loop systems and algorithms can be found in home appliances, automobiles, aviation and more. Can one imagine nowadays driving a car without ABS, cruise control or even anti-sliding control? Similar principles of automation and control can be used in the management of diabetes mellitus (DM). The idea of an algorithmic/technological way to control glycaemia is not new and has been researched for more than four decades. However, recent improvements in both glucose-sensing technology and insulin delivery together with advanced control and systems engineering made this dream of an artificial pancreas possible. The artificial pancreas may be the next big step in the treatment of DM since the use of insulin analogues. An artificial pancreas can be described as internal or external devices that use continuous glucose measurements to automatically manage exogenous insulin delivery with or without other hormones in an attempt to restore glucose regulation in individuals with DM using a control algorithm. This device as described can be internal or external; can use different types of control algorithms with bi-hormonal or uni-hormonal design; and can utilise different ways to administer them. The different designs and implementations have transitioned recently from in silico simulations to clinical evaluation stage with practical applications in mind. This may mark the beginning of a new era in diabetes management with the introduction of semi-closed-loop systems that can prevent or minimise nocturnal hypoglycaemia, to hybrid systems that will manage blood glucose (BG) levels with minimal user intervention to finally fully automated systems that will take the user out of the loop. More and more clinical trials will be needed for the artificial pancreas to become a reality but initial encouraging results are proof that we are on the right track. We attempted to select recent publications that will present these current achievements in the quest for the artificial pancreas and that will inspire others to continue to progress this field of research. PMID:21323809

Dassau, E; Atlas, E; Phillip, M

2011-02-01

316

Two loop divergences studied with one loop constrained differential renormalization  

NASA Astrophysics Data System (ADS)

In the context of differential renormalization, using constrained differential renormalization rules at one-loop, we show how to obtain concrete results in two-loop calculations without making use of Ward identities. In order to do that, we obtain a list of integrals with overlapping divergences compatible with CDR that can be applied to various two-loop background field calculations. As an example, we obtain the two-loop coefficient of the beta function of QED, SuperQED and Yang-Mills theory.

Seijas, Cesar

2007-08-01

317

Self-similar evaporation of a rigidly rotating cosmic string loop  

NASA Astrophysics Data System (ADS)

The gravitational back-reaction on a certain type of rigidly rotating cosmic string loop, first discovered by Allen, Casper and Ottewill, is studied at the level of the weak-field approximation. The near-field metric perturbations are calculated and used to construct the self-acceleration vector of the loop. Although the acceleration vector is divergent at the two kink points on the loop, its net effect on the trajectory over a single oscillation period turns out to be finite. The net back-reaction on the loop over a single period is calculated using a method due to Quashnock and Spergel, and is shown to induce a uniform shrinkage of the loop while preserving its original shape. The loop therefore evolves by self-similar evaporation.

Anderson, Malcolm

2005-07-01

318

Wilson loops as precursors  

SciTech Connect

There is substantial evidence that string theory on AdS{sub 5}xS{sub 5} is a holographic theory in which the number of degrees of freedom scales as the area of the boundary in Planck units. Precisely how the theory can describe bulk physics using only surface degrees of freedom is not well understood. A particularly paradoxical situation involves an event deep in the interior of the bulk space. The event must be recorded in the (Schroedinger picture) state vector of the boundary theory long before a signal, such as a gravitational wave, can propagate from the event to the boundary. In a previous paper with Polchinski, we argued that the ''precursor'' operators which carry information stored in the wave during the time when it vanishes in a neighborhood of the boundary are necessarily non-local. In this paper we argue that the precursors cannot be products of local gauge invariant operators such as the energy momentum tensor. In fact gauge theories have a class of intrinsically non-local operators which cannot be built from local gauge invariant objects. These are the Wilson loops. We show that the precursors can be identified with Wilson loops whose spatial size is dictated by the UV-IR connection. (c) 2000 The American Physical Society.

Susskind, Leonard [Department of Physics, Stanford University, Stanford, California 94305-4060 (United States)] [Department of Physics, Stanford University, Stanford, California 94305-4060 (United States); Toumbas, Nicolaos [Department of Physics, Stanford University, Stanford, California 94305-4060 (United States)] [Department of Physics, Stanford University, Stanford, California 94305-4060 (United States)

2000-02-15

319

Wilson Loops as Precursors  

E-print Network

There is substantial evidence that string theory on AdS_5 x S_5 is a holographic theory in which the number of degrees of freedom scales as the area of the boundary in Planck units. Precisely how the theory can describe bulk physics using only surface degrees of freedom is not well understood. A particularly paradoxical situation involves an event deep in the interior of the bulk space. The event must be recorded in the (Schroedinger Picture) state vector of the boundary theory long before a signal, such as a gravitational wave, can propagate from the event to the boundary. In a previous paper with Polchinski, we argued that the "precursor" operators which carry information stored in the wave during the time when it vanishes in a neighborhood of the boundary are necessarily non-local. In this paper we argue that the precursors cannot be products of local gauge invariant operators such as the energy momentum tensor. In fact gauge theories have a class of intrinsically non-local operators which cannot be built from local gauge invariant objects. These are the Wilson loops. We show that the precursors can be identified with Wilson loops whose spatial size is dictated by the UV-IR connection.

Leonard Susskind; Nicolaos Toumbas

2000-03-17

320

Ekpyrotic loop quantum cosmology  

SciTech Connect

We consider the ekpyrotic paradigm in the context of loop quantum cosmology. In loop quantum cosmology the classical big-bang singularity is resolved due to quantum gravity effects, and so the contracting ekpyrotic branch of the universe and its later expanding phase are connected by a smooth bounce. Thus, it is possible to explicitly determine the evolution of scalar perturbations, from the contracting ekpyrotic phase through the bounce and to the post-bounce expanding epoch. The possibilities of having either one or two scalar fields have been suggested for the ekpyrotic universe, and both cases will be considered here. In the case of a single scalar field, the constant mode of the curvature perturbations after the bounce is found to have a blue spectrum. On the other hand, for the two scalar field ekpyrotic model where scale-invariant entropy perturbations source additional terms in the curvature perturbations, the power spectrum in the post-bounce expanding cosmology is shown to be nearly scale-invariant and so agrees with observations.

Wilson-Ewing, Edward, E-mail: wilson-ewing@phys.lsu.edu [Department of Astronomy and Physics, Louisiana State University, Baton Rouge, 70803 (United States)

2013-08-01

321

Accelerating the loop expansion  

SciTech Connect

This thesis introduces a new non-perturbative technique into quantum field theory. To illustrate the method, I analyze the much-studied phi/sup 4/ theory in two dimensions. As a prelude, I first show that the Hartree approximation is easy to obtain from the calculation of the one-loop effective potential by a simple modification of the propagator that does not affect the perturbative renormalization procedure. A further modification then susggests itself, which has the same nice property, and which automatically yields a convex effective potential. I then show that both of these modifications extend naturally to higher orders in the derivative expansion of the effective action and to higher orders in the loop-expansion. The net effect is to re-sum the perturbation series for the effective action as a systematic ''accelerated'' non-perturbative expansion. Each term in the accelerated expansion corresponds to an infinite number of terms in the original series. Each term can be computed explicitly, albeit numerically. Many numerical graphs of the various approximations to the first two terms in the derivative expansion are given. I discuss the reliability of the results and the problem of spontaneous symmetry-breaking, as well as some potential applications to more interesting field theories. 40 refs.

Ingermanson, R.

1986-07-29

322

The double loop mattress suture  

PubMed Central

An interrupted stitch type with favorable tissue characteristics will reduce local wound complications. We describe a novel high-strength, low-tension repair for the interrupted closure of skin, cartilage, and muscle, the double loop mattress stitch, and compare it experimentally with other interrupted closure methods. The performance of the double loop mattress technique in porcine cartilage and skeletal muscle is compared with the simple, mattress, and loop mattress interrupted sutures in both a novel porcine loading chamber and mechanical model. Wound apposition is assessed by electron microscopy. The performance of the double loop mattress in vivo was confirmed using a series of 805 pediatric laparotomies/laparoscopies. The double loop mattress suture is 3.5 times stronger than the loop mattress in muscle and 1.6 times stronger in cartilage (p ? 0.001). Additionally, the double loop mattress reduces tissue tension by 66% compared with just 53% for the loop mattress (p ? 0.001). Wound gapping is equal, and wound eversion appears significantly improved (p ? 0.001) compared with the loop mattress in vitro. In vivo, the double loop mattress performs as well as the loop mattress and significantly better than the mattress stitch in assessments of wound eversion and dehiscence. There were no episodes of stitch extrusion in our series of patients. The mechanical advantage of its intrinsic pulley arrangement gives the double loop mattress its favorable properties. Wound dehiscence is reduced because this stitch type is stronger and exerts less tension on the tissue than the mattress stitch. We advocate the use of this novel stitch wherever a high-strength, low-tension repair is required. These properties will enhance wound repair, and its application will be useful to surgeons of all disciplines. PMID:24698436

Biddlestone, John; Samuel, Madan; Creagh, Terry; Ahmad, Tariq

2014-01-01

323

Chemical-looping hydrogen generation system: Performance estimation and process selection  

Microsoft Academic Search

To find a suitable metal component in an oxygen carrier particle for a chemical-looping hydrogen generation system (CLH),\\u000a oxygen transfer capacities of metal components were investigated, and Ni was selected as the best metal component. The optimum\\u000a operating conditions to have maximum hydrogen generation rate have been determined based on the chemical-equilibrium composition\\u000a analysis in a water splitting reactor. Moreover,

Ho-Jung Ryu; Gyoung-Tae Jin

2007-01-01

324

Open-loop adaptive filtering for speckle reduction in synthetic aperture radar images  

Microsoft Academic Search

The two-dimensional adaptive correlation enhancer algorithm (2DACE) is an open-loop adaptive filtering technique that can be applied to synthetic aperture radar (SAR) images for the purpose of reducing speckle. This paper includes the development of the 2DACE algorithm and the optimum filter parameters for this specific task. The unique implementation of 2DACE with a data amplitude pre-compression operation was proven

JUDD A. ROHWER; N. Magotra; S. D. Stearns

2000-01-01

325

Number of cosmic string loops  

NASA Astrophysics Data System (ADS)

Using recent simulation results, we provide the mass and speed spectrum of cosmic string loops. This is the quantity of primary interest for many phenomenological signatures of cosmic strings, and it can be accurately predicted using recently acquired detailed knowledge of the loop production function. We emphasize that gravitational smoothing of long strings plays a negligible role in determining the total number of existing loops. We derive a bound on the string tension imposed by recent constraints on the stochastic gravitational wave background from pulsar timing arrays, finding G? ?2.8×10-9. We also provide a derivation of the Boltzmann equation for cosmic string loops in the language of differential forms.

Blanco-Pillado, Jose J.; Olum, Ken D.; Shlaer, Benjamin

2014-01-01

326

[Optimum harvest study of Gentiana crassicaulis in Ludian].  

PubMed

The paper is aimed to study the difference in yield and quality at different harvest time and determine the optimum harvest of planting Gentiana in Ludian traditional harvest period. The authors analyzed the variation in fresh weight, dry weight, dry discount rate, length, diameter, volume and the content of gentiopicroside, loganin acid, alcohol-soluble extract and total ash and made a comprehensive appraisal of yield, appearance quality and intrinsic quality by gray relational distance ideal Comprehensive Evaluation method. The results showed that there is a big difference in yield and quality both 2-year-old and 3-year-old Gentiana harvested in traditional harvest period and the comprehensive evaluation more better when harvested more later. It can be seen, Gentiana harvested the later had a better yield and quality in Ludian traditional harvest period. The harvest of Gentiana can be appropriate delayed depending on the particular circumstances of production. PMID:25272487

Zeng, Yu; Chen, Xing-Fu; Zou, Yuan-Feng; Song, Jiu-Hua; Yang, Wen-Yu; Cheng, Tao

2014-07-01

327

Optimum Transmission Policies for Battery Limited Energy Harvesting Nodes  

E-print Network

Wireless networks with energy harvesting battery powered nodes are quickly emerging as a viable option for future wireless networks with extended lifetime. Equally important to their counterpart in the design of energy harvesting radios are the design principles that this new networking paradigm calls for. In particular, unlike wireless networks considered up to date, the energy replenishment process and the storage constraints of the rechargeable batteries need to be taken into account in designing efficient transmission strategies. In this work, we consider such transmission policies for rechargeable nodes, and identify the optimum solution for two related problems. Specifically, the transmission policy that maximizes the short term throughput, i.e., the amount of data transmitted in a finite time horizon is found. In addition, we show the relation of this optimization problem to another, namely, the minimization of the transmission completion time for a given amount of data, and solve that as well. The tra...

Tutuncuoglu, Kaya

2010-01-01

328

A new approach to optimum design in thermoelectric cooling systems  

NASA Astrophysics Data System (ADS)

A thermoelectric cooling system usually consists of a thermoelectric cooler (TEC) and heat exchangers at the cold side and the hot side. Heat exchangers in TEC systems are designed to minimize their thermal resistance under restrictions such as the size of the system and heat transfer method, because as the thermal resistances of heat exchangers increase, the performance of TEC systems decreases. In the TEC system in which thermal resistance of heat exchangers is minimized, the optimum TEC is analyzed to maximize the coefficient of performance (COP) and the exergetic efficiency in absorbing a given heat load. The effects of the thermal resistance of heat exchangers on the performance of the TEC system and the design parameters of that system are also investigated. To discuss these matters, dimensionless entropy flow equations of the TEC system are introduced, and the COP and the exergetic efficiency are expressed as a function of dimensionless quantities by using these dimensionless equations.

Yamanashi, M.

1996-11-01

329

Optimum periodicity of repeated contractile actions applied in mass transport  

PubMed Central

Dynamically repeated periodic patterns are abundant in natural and artificial systems, such as tides, heart beats, stock prices, and the like. The characteristic repeatability and periodicity are expected to be optimized in effective system-specific functions. In this study, such optimum periodicity is experimentally evaluated in terms of effective mass transport using one-valve and multi-valve systems working in contractile fluid flows. A set of nanoscale gating functions is utilized, operating in nanocomposite networks through which permeates selectively pass under characteristic contractile actions. Optimized contractile periodicity exists for effective energy impartment to flow in a one-valve system. In the sequential contractile actions for a multi-valve system, synchronization with the fluid flow is critical for effective mass transport. This study provides fundamental understanding on the various repeated periodic patterns and dynamic repeatability occurring in nature and mechanical systems, which are useful for broad applications. PMID:25622949

Ahn, Sungsook; Lee, Sang Joon

2015-01-01

330

A Decision Support System for Optimum Use of Fertilizers  

SciTech Connect

The Decision Support System for Agriculture (DSS4Ag) is an expert system being developed by the Site-Specific Technologies for Agriculture (SST4Ag) precision farming research project at the INEEL. DSS4Ag uses state-of-the-art artificial intelligence and computer science technologies to make spatially variable, site-specific, economically optimum decisions on fertilizer use. The DSS4Ag has an open architecture that allows for external input and addition of new requirements and integrates its results with existing agricultural systems’ infrastructures. The DSS4Ag reflects a paradigm shift in the information revolution in agriculture that is precision farming. We depict this information revolution in agriculture as an historic trend in the agricultural decision-making process.

Hoskinson, Reed Louis; Hess, John Richard; Fink, Raymond Keith

1999-07-01

331

A Decision Support System for Optimum Use of Fertilizers  

SciTech Connect

The Decision Support System for Agriculture (DSS4Ag) is an expert system being developed by the Site-Specific Technologies for Agriculture (SST4Ag) precision farming research project at the INEEL. DSS4Ag uses state-of-the-art artificial intelligence and computer science technologies to make spatially variable, site-specific, economically optimum decisions on fertilizer use. The DSS4Ag has an open architecture that allows for external input and addition of new requirements and integrates its results with existing agricultural systems' infrastructures. The DSS4Ag reflects a paradigm shift in the information revolution in agriculture that is precision farming. We depict this information revolution in agriculture as an historic trend in the agricultural decision-making process.

R. L. Hoskinson; J. R. Hess; R. K. Fink

1999-07-01

332

Optimum periodicity of repeated contractile actions applied in mass transport  

NASA Astrophysics Data System (ADS)

Dynamically repeated periodic patterns are abundant in natural and artificial systems, such as tides, heart beats, stock prices, and the like. The characteristic repeatability and periodicity are expected to be optimized in effective system-specific functions. In this study, such optimum periodicity is experimentally evaluated in terms of effective mass transport using one-valve and multi-valve systems working in contractile fluid flows. A set of nanoscale gating functions is utilized, operating in nanocomposite networks through which permeates selectively pass under characteristic contractile actions. Optimized contractile periodicity exists for effective energy impartment to flow in a one-valve system. In the sequential contractile actions for a multi-valve system, synchronization with the fluid flow is critical for effective mass transport. This study provides fundamental understanding on the various repeated periodic patterns and dynamic repeatability occurring in nature and mechanical systems, which are useful for broad applications.

Ahn, Sungsook; Lee, Sang Joon

2015-01-01

333

Simpler Alternative to an Optimum FQPSK-B Viterbi Receiver  

NASA Technical Reports Server (NTRS)

A reduced-complexity alternative to an optimum FQPSK-B Viterbi receiver has been invented. As described, the reduction in complexity is achieved at the cost of only a small reduction in power performance [performance expressed in terms of a bit-energy-to-noise-energy ratio (Eb/N0) for a given bit-error rate (BER)]. The term "FQPSK-B" denotes a baseband-filtered version of Feher quadrature-phase-shift keying, which is a patented, bandwidth-efficient phase-modulation scheme named after its inventor. Heretofore, commercial FQPSK-B receivers have performed symbol-by-symbol detection, in each case using a detection filter (either the proprietary FQPSK-B filter for better BER performance, or a simple integrate-and-dump filter with degraded performance) and a sample-and-hold circuit.

Lee, Dennis; Simon, Marvin; Yan, Tsun-Yee

2003-01-01

334

Generation and evoluation of near-optimum vertical flight profiles  

NASA Technical Reports Server (NTRS)

The overall objectives of this research effort have been to develop and evaluate algorithms and flight management concepts for minimization of fuel or direct operating costs. These concepts are to be used for flight planning or for on-board computation and steering of turbojet transport aircraft in the vertical path. Within this research context, a computer program, called OPTIM, has been developed to use these algorithms to generate near-optimum vertical reference profiles. OPTIM contains control options to examine effects of various flight constraints on cost performance. A companion program, called TRAGEN, was developed to simulate an aircraft flying along a given vertical reference profile. TRAGEN is used to verify OPTIM's output , to examine the effects of parameter value uncertainty (such as prevailing wind), and to compare cost performance of profiles generated by different techniques. This paper describes OPTIM and TRAGEN and presents examples of the programs utility.

Sorensen, J. A.

1983-01-01

335

Optimum detection of tones transmitted by a spacecraft  

NASA Technical Reports Server (NTRS)

The performance of a scheme proposed for automated routine monitoring of deep-space missions is presented. The scheme uses four different tones (sinusoids) transmitted from the spacecraft (S/C) to a ground station with the positive identification of each of them used to indicate different states of the S/C. Performance is measured in terms of detection probability versus false alarm probability with detection signal-to-noise ratio as a parameter. The cases where the phase of the received tone is unknown and where both the phase and frequency of the received tone are unknown are treated separately. The decision rules proposed for detecting the tones are formulated from average-likelihood ratio and maximum-likelihood ratio tests, the former resulting in optimum receiver structures.

Simon, M. K.; Shihabi, M. M.; Moon, T.

1995-01-01

336

Optimum hot water temperature for absorption solar cooling  

SciTech Connect

The hot water temperature that maximizes the overall instantaneous efficiency of a solar cooling facility is determined. A modified characteristic equation model is used and applied to single-effect lithium bromide-water absorption chillers. This model is based on the characteristic temperature difference and serves to empirically calculate the performance of real chillers. This paper provides an explicit equation for the optimum temperature of vapor generation, in terms of only the external temperatures of the chiller. The additional data required are the four performance parameters of the chiller and essentially a modified stagnation temperature from the detailed model of the thermal collector operation. This paper presents and discusses the results for small capacity machines for air conditioning of homes and small buildings. The discussion highlights the influence of the relevant parameters. (author)

Lecuona, A.; Ventas, R.; Venegas, M.; Salgado, R. [Dpto. Ingenieria Termica y de Fluidos, Universidad Carlos III de Madrid, Avda. Universidad 30, 28911 Leganes, Madrid (Spain); Zacarias, A. [ESIME UPA, IPN, Av. de las Granjas 682, Col. Santa Catarina, 02550, D.F. Mexico (Mexico)

2009-10-15

337

Optimum lattice arrangement developed from a rigorous analytical basis  

NASA Technical Reports Server (NTRS)

The spanwise vortex-lattice arrangement is mathematically established by lattice solutions of the slender wing which are shown to be analogous to the chordwise vortex-lattice thin wing solution. Solutions for any number N of panels wing theory lift and induced drag and thin wing theory lift and moment are predicted exactly. As N approaches infinity, the slender wing elliptic spanwise loading and thin wing cotangent chordwise loading are predicted, which proves there is mathematical convergence of the vortex-lattice method to the exact answer. Based on this planform spanwise lattice arrangement, an A-vortex-lattice spanwise system is developed for an arbitrary aspect ratio A. This A-lattice has the optimum characteristic of predicting lift accurately for any value of N.

Deyoung, J.

1976-01-01

338

Optimum Actuator Selection with a Genetic Algorithm for Aircraft Control  

NASA Technical Reports Server (NTRS)

The placement of actuators on a wing determines the control effectiveness of the airplane. One approach to placement maximizes the moments about the pitch, roll, and yaw axes, while minimizing the coupling. For example, the desired actuators produce a pure roll moment without at the same time causing much pitch or yaw. For a typical wing, there is a large set of candidate locations for placing actuators, resulting in a substantially larger number of combinations to examine in order to find an optimum placement satisfying the mission requirements and mission constraints. A genetic algorithm has been developed for finding the best placement for four actuators to produce an uncoupled pitch moment. The genetic algorithm has been extended to find the minimum number of actuators required to provide uncoupled pitch, roll, and yaw control. A simplified, untapered, unswept wing is the model for each application.

Rogers, James L.

2004-01-01

339

Optimum periodicity of repeated contractile actions applied in mass transport.  

PubMed

Dynamically repeated periodic patterns are abundant in natural and artificial systems, such as tides, heart beats, stock prices, and the like. The characteristic repeatability and periodicity are expected to be optimized in effective system-specific functions. In this study, such optimum periodicity is experimentally evaluated in terms of effective mass transport using one-valve and multi-valve systems working in contractile fluid flows. A set of nanoscale gating functions is utilized, operating in nanocomposite networks through which permeates selectively pass under characteristic contractile actions. Optimized contractile periodicity exists for effective energy impartment to flow in a one-valve system. In the sequential contractile actions for a multi-valve system, synchronization with the fluid flow is critical for effective mass transport. This study provides fundamental understanding on the various repeated periodic patterns and dynamic repeatability occurring in nature and mechanical systems, which are useful for broad applications. PMID:25622949

Ahn, Sungsook; Lee, Sang Joon

2015-01-01

340

Incorporating spatial criteria in optimum reserve network selection.  

PubMed Central

Considering the spatial location of sites that are to be selected for inclusion in a protected reserve network may be necessary to facilitate dispersal and long-term persistence of species in the selected sites. This paper presents an integer programming (IP) approach to the reserve network selection problem where spatial considerations based on intersite distances are taken into account when selecting reserve sites. The objective is to reduce the fragmentation of preserved sites and design a compact reserve network. Two IP formulations are developed which minimize the sum of pairwise distances and the maximum intersite distance between all sites in the reserve network, respectively, while representing all species under consideration. This approach is applied to a pond invertebrate dataset consisting of 131 sites containing 256 species in Oxfordshire, UK. The results show that significant reductions in reserve fragmentation can be achieved, compared with spatially unrestricted optimum reserve selection, at the expense of a small loss in reserve efficiency. PMID:12495486

Onal, Hayri; Briers, Robert A

2002-01-01

341

Optimum detection of an optical image on a photoelectric surface  

NASA Technical Reports Server (NTRS)

The detection of an optical image in the presence of uniform background light is based on a likelihood ratio formed of the numbers of photoelectrons emitted from small elements of a photoelectric surface onto which the image is focused. When diffraction is negligible and the surface has unit quantum efficiency, this detector is equipollent with the optimum detector of the image forming light. Its performance is compared with that of the threshold detector and that of a detector basing its decisions on the total number of photoelectrons from a finite area of the image. The illuminance of the image is postulated to have a Gaussian spatial distribution. All three detectors exhibit nearly the same reliability.

Helstrom, C. W.; Wang, L.

1972-01-01

342

The optimum choice of gate width for neutron coincidence counting  

NASA Astrophysics Data System (ADS)

In the measurement field of international nuclear safeguards, passive neutron coincidence counting is used to quantify the spontaneous fission rate of certain special nuclear materials. The shift register autocorrelation analysis method is the most commonly used approach. However, the Feynman-Y technique, which is more commonly applied in reactor noise analysis, provides an alternative means to extract the correlation information from a pulse train. In this work we consider how to select the optimum gate width for each of these two time-correlation analysis techniques. The optimum is considered to be that which gives the lowest fractional precision on the net doublets rate. Our theoretical approach is approximate but is instructional in terms of revealing the key functional dependence. We show that in both cases the same performance figure of merit applies so that common design criteria apply to the neutron detector head. Our prediction is that near optimal results, suitable for most practical applications, can be obtained from both techniques using a common gate width setting. The estimated precision is also comparable in the two cases. The theoretical expressions are tested experimentally using 252Cf spontaneous fission sources measured in two thermal well counters representative of the type in common use by international inspectorates. Fast accidental sampling was the favored method of acquiring the Feynman-Y data. Our experimental study confirmed the basic functional dependences predicted although experimental results when available are preferred. With an appropriate gate setting Feynman-Y analysis provides an alternative to shift register analysis for safeguards applications which is opening up new avenues of data collection and data reduction to explore.

Croft, S.; Henzlova, D.; Favalli, A.; Hauck, D. K.; Santi, P. A.

2014-11-01

343

Shape Dynamics and Effective Field Theory  

E-print Network

Shape Dynamics is a gauge theory based on spatial diffeomorphism- and Weyl-invariance which is locally indistinguishable form classical General Relativity. If taken seriously, it suggests that the spacetime--geometry picture that underlies General Relativity can be replaced by a picture based on spatial conformal geometry. This classically well understood trading of gauge symmetries opens new conceptual avenues in many approaches to quantum gravity. I focus on the general implications for quantum gravity and effective field theory and consider the application of the Shape Dynamics picture in the exact renormalization group approaches to gravity, loop- and polymer- quantization approaches to gravity and low energy effective field theories. I also discuss the interpretation of known results through in the Shape Dynamics picture, in particular holographic renormalization and the problem of time in canonical quantum gravity.

Tim Koslowski

2013-05-07

344

Identification of optimum scopes of environmental factors for snails using spatial analysis techniques in Dongting Lake Region, China  

PubMed Central

Background Owing to the harmfulness and seriousness of Schistosomiasis japonica in China, the control and prevention of S. japonica transmission are imperative. As the unique intermediate host of this disease, Oncomelania hupensis plays an important role in the transmission. It has been reported that the snail population in Qiangliang Lake district, Dongting Lake Region has been naturally declining and is slowly becoming extinct. Considering the changes of environmental factors that may cause this phenomenon, we try to explore the relationship between circumstance elements and snails, and then search for the possible optimum scopes of environmental factors for snails. Methods Moisture content of soil, pH, temperature of soil and elevation were collected by corresponding apparatus in the study sites. The LISA statistic and GWR model were used to analyze the association between factors and mean snail density, and the values in high-high clustered areas and low-low clustered areas were extracted to find out the possible optimum ranges of these elements for snails. Results A total of 8,589 snail specimens were collected from 397 sampling sites in the study field. Besides the mean snail density, three environmental factors including water content, pH and temperature had high spatial autocorrelation. The spatial clustering suggested that the possible optimum scopes of moisture content, pH, temperature of the soil and elevation were 58.70 to 68.93%, 6.80 to 7.80, 22.73 to 24.23°C and 23.50 to 25.97 m, respectively. Moreover, the GWR model showed that the possible optimum ranges of these four factors were 36.58 to 61.08%, 6.541 to 6.89, 24.30 to 25.70°C and 23.50 to 29.44 m, respectively. Conclusion The results indicated the association between snails and environmental factors was not linear but U-shaped. Considering the results of two analysis methods, the possible optimum scopes of moisture content, pH, temperature of the soil and elevation were 58.70% to 68.93%, 6.6 to 7.0, 22.73°C to 24.23°C, and 23.5 m to 26.0 m, respectively. The findings in this research will help in making an effective strategy to control snails and provide a method to analyze other factors. PMID:24886456

2014-01-01

345

Vortex loops and Majoranas  

SciTech Connect

We investigate the role that vortex loops play in characterizing eigenstates of interacting Majoranas. We give some general results and then focus on ladder Hamiltonian examples as a test of further ideas. Two methods yield exact results: (i) A mapping of certain spin Hamiltonians to quartic interactions of Majoranas shows that the spectra of these two examples coincide. (ii) In cases with reflection-symmetric Hamiltonians, we use reflection positivity for Majoranas to characterize vortices in the ground states. Two additional methods suggest wider applicability of these results: (iii) Numerical evidence suggests similar behavior for certain systems without reflection symmetry. (iv) A perturbative analysis also suggests similar behavior without the assumption of reflection symmetry.

Chesi, Stefano [Department of Physics, McGill University, Montreal, Quebec H3A 2T8 (Canada) [Department of Physics, McGill University, Montreal, Quebec H3A 2T8 (Canada); CEMS, RIKEN, Wako, Saitama 351-0198 (Japan); Jaffe, Arthur [Harvard University, Cambridge, Massachusetts 02138 (United States) [Harvard University, Cambridge, Massachusetts 02138 (United States); Department of Physics, University of Basel, Basel (Switzerland); Institute for Theoretical Physics, ETH Zürich, Zürich (Switzerland); Loss, Daniel [CEMS, RIKEN, Wako, Saitama 351-0198 (Japan) [CEMS, RIKEN, Wako, Saitama 351-0198 (Japan); Department of Physics, University of Basel, Basel (Switzerland); Pedrocchi, Fabio L. [Department of Physics, University of Basel, Basel (Switzerland)] [Department of Physics, University of Basel, Basel (Switzerland)

2013-11-15

346

Phase-Locked Loops  

NSDL National Science Digital Library

Phase-locked loops (PLL) are unique feedback control circuits that offer many useful features and benefits in electronic applications. PLLs are available either in integrated circuit (IC) form for general applications or built into larger system IC chips. Today, PLLs are found in virtually all types of electronic equipment from PCs to consumer products like TV sets and cell phones. This module provides an introduction to the PLL and its applications. It begins with an overview of the main components of a PLL and how these components work together. It then describes PLL specifications and a description of the most widely used applications including frequency synthesizers, clock multipliers, clock and data recovery circuits, FM demodulators, and filters.

347

Dynamic PID loop control  

SciTech Connect

The Horizontal Test Stand (HTS) SRF Cavity and Cryomodule 1 (CM1) of eight 9-cell, 1.3GHz SRF cavities are operating at Fermilab. For the cryogenic control system, how to hold liquid level constant in the cryostat by regulation of its Joule-Thompson JT-valve is very important after cryostat cool down to 2.0 K. The 72-cell cryostat liquid level response generally takes a long time delay after regulating its JT-valve; therefore, typical PID control loop should result in some cryostat parameter oscillations. This paper presents a type of PID parameter self-optimal and Time-Delay control method used to reduce cryogenic system parameters oscillation.

Pei, L.; Klebaner, A.; Theilacker, J.; Soyars, W.; Martinez, A.; Bossert, R.; DeGraff, B.; Darve, C.; /Fermilab

2011-06-01

348

Optimum linear array for aperture synthesis imaging based on redundant spacing calibration  

NASA Astrophysics Data System (ADS)

Aperture synthesis imaging has been proved to be attractive in surveillance and detection applications. Such an imaging process is inevitably subject to aberrations introduced by instrument defects and/or turbulent media. Redundant spacing calibration (RSC) technique allows continuous calibration of these errors at any electromagnetic wavelength. However, it is based on specially designed array, in which just enough redundancy is included to permit the successful implementation of RSC. A new design criterion for linear RSC array is described, which introduces coverage efficiency and redundancy efficiency factors, aiming to find the perfect configurations, which have as complete uv-plane coverage as possible while containing required redundancy. Optimum linear arrays for N (number of subapertures) up to 10 are listed based on simulated annealing algorithm. The comparisons with existing linear RSC arrays with equivalent subaperture number are implemented. Results show that the optimized arrays have better performance of both optical transfer function, point spread function, and object reconstruction with reasonable value of the matrix condition number. After that, linear arrays are used to construct two-dimensional (2-D) pseudo-Y-shaped RSC arrays, which give a way to design 2-D RSC arrays without exhaustive searches.

Liu, Li; He, Yuntao; Zhang, Jianguo; Jia, Huayu; Ma, Jun

2014-05-01

349

Sodium loop framework structural analysis  

SciTech Connect

This document provides the structural analysis of the Sodium Loop framework in a drop condition. The drop is similar to the US Department of Transportation non-bulk, performance-oriented packaging (Packaging Group I) drop test. The drop height evaluated for the Sodium Loop framework is 5.9 ft.

Nguyen, P.M.

1995-06-06

350

TRIAL MANUFACTURE OF BISMUTH LOOP  

Microsoft Academic Search

The outline of the structure of a bismuth loop is given. The loop was ; charged with bismuth by pressurizing the sumptank with nitrogen gas. In ; operation, the bismuth was pumped by means of a mechanical pump to III, II, and I ; vessels and a flowmeter. The temperature of bismuth metal was controlled at 550 ; deg C

S. Yajima; Y. Kamemoto; Y. Takahashi

1963-01-01

351

Thermodynamics in Loop Quantum Cosmology  

Microsoft Academic Search

Loop quantum cosmology (LQC) is very powerful to deal with the behavior of early universe. And the effective loop quantum cosmology gives a successful description of the universe in the semiclassical region. We consider the apparent horizon of the Friedmann-Robertson-Walker universe as a thermodynamical system and investigate the thermodynamics of LQC in the semiclassical region. The effective density and effective

Li-Fang Li; Jian-Yang Zhu

2009-01-01

352

Heating of braided coronal loops  

NASA Astrophysics Data System (ADS)

Aims: We investigate the relaxation of braided magnetic loops in order to find out how the type of braiding via footpoint motions affects resultant heating of the loop. Methods: Two magnetic loops, braided in different ways, are used as initial conditions in resistive MHD simulations and their subsequent evolution is studied. Results: The fields both undergo a resistive relaxation in which current sheets form and fragment and the system evolves towards a state of lower energy. In one case this relaxation is very efficient with current sheets filling the volume and homogeneous heating of the loop occurring. In the other case fewer current sheets develop, less magnetic energy is released in the process and a patchy heating of the loop results. The two cases, although very similar in their setup, can be distinguished by the mixing properties of the photospheric driver. The mixing can be measured by the topological entropy of the plasma flow, an observable quantity.

Wilmot-Smith, A. L.; Pontin, D. I.; Yeates, A. R.; Hornig, G.

2011-12-01

353

Loop Heat Pipe Startup Behaviors  

NASA Technical Reports Server (NTRS)

A loop heat pipe must start successfully before it can commence its service. The start-up transient represents one of the most complex phenomena in the loop heat pipe operation. This paper discusses various aspects of loop heat pipe start-up behaviors. Topics include the four start-up scenarios, the initial fluid distribution between the evaporator and reservoir that determines the start-up scenario, factors that affect the fluid distribution between the evaporator and reservoir, difficulties encountered during the low power start-up, and methods to enhance the start-up success. Also addressed are the thermodynamic constraint between the evaporator and reservoir in the loop heat pipe operation, the superheat requirement for nucleate boiling, pressure spike and pressure surge during the start-up transient, and repeated cycles of loop start-up andshutdown under certain conditions.

Ku, Jentung

2014-01-01

354

Optimum conditions for prebiotic evolution in extraterrestrial environments  

NASA Astrophysics Data System (ADS)

The overall goal of the dissertation was to devise synthetic pathways leading to the production of peptides and amino acids from smaller organic precursors. To this end, eight different zeolites were tested in order to determine their catalytic potential in the conversion of amino acids to peptides. The zeolites tested were either synthetic or naturally occurring. Acidic solutions of amino acids were prepared with or without zeolites and their reactivity was monitored over a four-week time interval. The kinetics and feasibility of peptide synthesis from selected amino acid combinations was investigated via the paper chromatography technique. Nine different amino acids were tested. The nature and extent of product were measured at constant time intervals. It was found that two ZSM-5 synthetic zeolites as well as the Fisher Scientific zeolite mix without alumina salts may have a catalytic potential in the conversion of amino acids to peptides. The conversion was verified by matching the paper chromatogram of the experimental product with that of a known peptide. The experimental results demonstrate that the optimum solvent system for paper chromatographic analysis of the zeolite-catalyzed self-assembly of the amino acids L-aspartic acid, L- asparagine, L-histidine, and L-serine is a 50:50 mixture of 1-butanol and acetone by volume. For the amino acids L-alanine, L-glycine, and L-valine, the optimum solvent was found to be a 30:70 mixture of ammonia and propanol by volume. A mathematical model describing the distance traveled (spot position) versus reaction time was constructed for the zeolite-catalyzed conversion of L- leucine and L-tyrosine and was found to approximately follow the function f(t) = 25 ln t. Two case studies for prebiotic synthesis leading to the production of amino acids or peptides in extraterrestrial environments were discussed: one involving Saturn's moon Titan, and the other involving Jupiter's moon Europa. In the Titan study, it was determined that organic synthesis, based on simple precursors, may lead in the Titan environment to the production of biologically important molecules such as amino acids. In the Europa study, three synthetic schemes using hydrogen peroxide, sulfuric acid, and hydrocyanic acid, and leading to the production of larger biologically important molecules such as amino acids were presented. (Abstract shortened by UMI.)

Abbas, Ousama H.

355

Tooth - abnormal shape  

MedlinePLUS

... many different conditions. Specific diseases can affect tooth shape, tooth color, time of appearance, or absence of teeth. ... any medical conditions that may cause abnormal tooth shape? At what age ... spacing)? What other symptoms are also present? Fillings, ...

356

Post the Shapes  

NSDL National Science Digital Library

In this game students use basic transformations (sliding, flipping and turning) to make one or more shapes coincide with a congruent shape on a Cartesian plane. Players are challenged to complete the matching in the fewest possible moves.

2011-01-01

357

Fun with Shapes  

NSDL National Science Digital Library

In this activity, early learners combine pre-cut recognizable shapes and their own abstract ideas to make representational pictures (e.g. houses, trees, shoes). This exploration of shape identification and transformation develops problem-solving skills. Use the provided open-ended questions to help learners communicate the processes they used to select shapes and colors as well as develop and practice a vocabulary of color and shapes.

2012-08-23

358

Changes in lung tumor shape during respiration  

NASA Astrophysics Data System (ADS)

Evidence that some lung tumors change shape during respiration is derived from respiratory gated CT data by statistical shape modeling and image manipulation. Some tumors behave as rigid objects while others show systematic shape changes. Two views of lung motion are presented to allow analysis of the results. In the first, lung motion is viewed as a wave motion in which inertial effects arising from mass are present and in the second it is a quasistatic motion in which the mass of the lung tissues is neglected. In the first scenario, the extremes of tumor compression and expansion are expected to correlate with maximum upward and downward velocity of the tumor, respectively. In the second, they should occur at end exhale and end inhale, respectively. An observed correlation between tumor strain and tumor velocity provides more support for the first view of lung motion and may explain why previous attempts at observing tumor shape changes during respiration have largely failed. The implications for the optimum gating of radiation therapy are discussed.

Kyriakou, E.; McKenzie, D. R.

2012-02-01

359

LacI-DNA-IPTG loops: equilibria among conformations by single-molecule FRET.  

PubMed

The E. coli Lac repressor (LacI) tetramer binds simultaneously to a promoter-proximal DNA binding site (operator) and an auxiliary operator, resulting in a DNA loop, which increases repression efficiency. Induction of the lac operon by allolactose reduces the affinity of LacI for DNA, but induction does not completely prevent looping in vivo. Our previous work on the conformations of LacI loops used a hyperstable model DNA construct, 9C14, that contains a sequence directed bend flanked by operators. Single-molecule fluorescence resonance energy transfer (SM-FRET) on a dual fluorophore-labeled LacI-9C14 loop showed that it adopts a single, stable, high-FRET V-shaped LacI conformation. Ligand-induced changes in loop geometry can affect loop stability, and the current work assesses loop population distributions for LacI-9C14 complexes containing the synthetic inducer IPTG. SM-FRET confirms that the high-FRET LacI-9C14 loop is only partially destabilized by saturating IPTG. LacI titration experiments and FRET fluctuation analysis suggest that the addition of IPTG induces loop conformational dynamics and re-equilibration between loop population distributions that include a mixture of looped states that do not exhibit high-efficiency FRET. The results show that repression by looping even at saturating IPTG should be considered in models for regulation of the operon. We propose that persistent DNA loops near the operator function biologically to accelerate rerepression upon exhaustion of inducer. PMID:23406418

Goodson, Kathy A; Wang, Zifan; Haeusler, Aaron R; Kahn, Jason D; English, Douglas S

2013-04-25

360

Early structure formation from cosmic string loops  

SciTech Connect

We examine the effects of cosmic strings on structure formation and on the ionization history of the universe. While Gaussian perturbations from inflation are known to provide the dominant contribution to the large scale structure of the universe, density perturbations due to strings are highly non-Gaussian and can produce nonlinear structures at very early times. This could lead to early star formation and reionization of the universe. We improve on earlier studies of these effects by accounting for high loop velocities and for the filamentary shape of the resulting halos. We find that for string energy scales G??>10{sup ?7}, the effect of strings on the CMB temperature and polarization power spectra can be significant and is likely to be detectable by the Planck satellite. We mention shortcomings of the standard cosmological model of galaxy formation which may be remedied with the addition of cosmic strings, and comment on other possible observational implications of early structure formation by strings.

Shlaer, Benjamin; Vilenkin, Alexander [Institute of Cosmology, Department of Physics and Astronomy, Tufts University, 212 College Avenue, Medford, MA 02155 (United States); Loeb, Abraham, E-mail: shlaer@cosmos.phy.tufts.edu, E-mail: vilenkin@cosmos.phy.tufts.edu, E-mail: aloeb@cfa.harvard.edu [Institute for Theory and Computation, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA, 02138 (United States)

2012-05-01

361

Shape Optimization of Rubber Bushing Using Differential Evolution Algorithm  

PubMed Central

The objective of this study is to design rubber bushing at desired level of stiffness characteristics in order to achieve the ride quality of the vehicle. A differential evolution algorithm based approach is developed to optimize the rubber bushing through integrating a finite element code running in batch mode to compute the objective function values for each generation. Two case studies were given to illustrate the application of proposed approach. Optimum shape parameters of 2D bushing model were determined by shape optimization using differential evolution algorithm. PMID:25276848

2014-01-01

362

Querying Shapes of Histories  

Microsoft Academic Search

We present a shape definition language, called SDC, for retrieving objects based on shapes contained in the histories associated with these objects. It is a small, yet powerful, language that allows a rich variety of queries about the shapes found in historical time sequences. An interesting feature of SDC is its ability to perform blurry matching. A \\

Rakesh Agrawal; Giuseppe Psaila; Edward L. Wimmers; Mohamed Zaït

1995-01-01

363

Shaped charge perforating device  

Microsoft Academic Search

A shaped charge perforating apparatus is described which consists of: an elongated tubular housing member having recesses spirally spaced therealong; an elongated tubular carrier member having shaped charge mounting locations spirally spaced therealong; a plurality of shaped charge units positioned in the mounting locations of the carrier member; a length of detonator cord helically wound about the tubular carrier member

Ayers

1986-01-01

364

The Hue of Shapes  

ERIC Educational Resources Information Center

This article presents an experimental study on the naturally biased association between shape and color. For each basic geometric shape studied, participants were asked to indicate the color perceived as most closely related to it, choosing from the Natural Color System Hue Circle. Results show that the choices of color for each shape were not…

Albertazzi, Liliana; Da Pos, Osvaldo; Canal, Luisa; Micciolo, Rocco; Malfatti, Michela; Vescovi, Massimo

2013-01-01

365

3D Shapes Video  

NSDL National Science Digital Library

This upbeat music video reviews 3D shapes including the sphere, cylinder, cube, and cone. As each 3D shape is presented, examples of things we see every day that have the same shape are also shown for reinforcement. (Length: 3:18)

Harry Kindergarten

2011-06-17

366

Coronal loops above an active region: Observation versus model  

NASA Astrophysics Data System (ADS)

We conducted a high-resolution numerical simulation of the solar corona above a stable active region. The aim is to test the field line braiding mechanism for a sufficient coronal energy input. We also check the applicability of scaling laws for coronal loop properties like the temperature and density. Our 3D MHD model is driven from below by Hinode observations of the photosphere, in particular a high-cadence time series of line-of-sight magnetograms and horizontal velocities derived from the magnetograms. This driving applies stress to the magnetic field and thereby delivers magnetic energy into the corona, where currents are induced that heat the coronal plasma by Ohmic dissipation. We compute synthetic coronal emission that we directly compare to coronal observations of the same active region taken by Hinode. In the model, coronal loops form at the same places as they are found in coronal observations. Even the shapes of the synthetic loops in 3D space match those found from a stereoscopic reconstruction based on STEREO spacecraft data. Some loops turn out to be slightly over-dense in the model, as expected from observations. This shows that the spatial and temporal distribution of the Ohmic heating produces the structure and dynamics of a coronal loops system close to what is found in observations.

Bourdin, Philippe-A.; Bingert, Sven; Peter, Hardi

2014-12-01

367

Optimum Binary Search Trees on the Hierarchical Memory Model  

E-print Network

The Hierarchical Memory Model (HMM) of computation is similar to the standard Random Access Machine (RAM) model except that the HMM has a non-uniform memory organized in a hierarchy of levels numbered 1 through h. The cost of accessing a memory location increases with the level number, and accesses to memory locations belonging to the same level cost the same. Formally, the cost of a single access to the memory location at address a is given by m(a), where m: N -> N is the memory cost function, and the h distinct values of m model the different levels of the memory hierarchy. We study the problem of constructing and storing a binary search tree (BST) of minimum cost, over a set of keys, with probabilities for successful and unsuccessful searches, on the HMM with an arbitrary number of memory levels, and for the special case h=2. While the problem of constructing optimum binary search trees has been well studied for the standard RAM model, the additional parameter m for the HMM increases the combinatorial comp...

Thite, Shripad

2008-01-01

368

Toward the global optimum in zoom lens design  

NASA Astrophysics Data System (ADS)

After more than a century from the introduction of zoom lenses, the selection of the right zoom lens type for a given specification is still a challenge for the optical designer. In the process of lens design, the optical designer is permanently searching for the best zoom lens structure in order to fulfill the complex balance between weight, cost and optical performance. This is a continuous optimization process and the result is a global optimum. The most important factors influencing zoom lens cost are: the number of spherical and aspherical lenses, the number of moving groups and lenses and finally the group sensitivity to displacement and tilt. Every lens group whether moving or not inside the zoom lens, has a specific complexity and sensitivity behavior dependent on the zoom lens type. It is not obvious which type of zoom lens will optimally satisfy the required specification. This paper describes the selection process exemplary for a zoom lens with a medium focal length range from 28mm to 80mm and a quasi constant f-number (FNO) during zooming. The lens is used mainly for cinematographic applications and must be able to maintain best image position for the entire range of object positions during zooming. Alternative solutions with their advantages and disadvantages are shown, analyzed and evaluated.

Dodoc, Aurelian

2012-10-01

369

Optimum circuit design for the detection of laser photodetachment signals  

NASA Astrophysics Data System (ADS)

Laser photodetachment is a widely used diagnostic technique for the detection of negative ions in low-temperature plasma sources. In one common method electrons, photodetached from the negative ions by an incident laser beam, are collected by a Langmuir probe biased above the local plasma potential. The photodetachment current signal, transmitted through the Langmuir probe feedthrough and interconnecting cables (transmission circuit), is converted into a voltage signal by a detection circuit. The negative ion density and temperature (using the two-pulse technique) are obtained from signal processing. Circuit analysis of the signal acquisition circuit, both transmission and detection parts, is used to obtain the design criteria for the undistorted transmission of the photodetachment signal. The effects of changing the circuit parameters from their optimum values are investigated experimentally in a conventional low-pressure magnetron system. The results show that an inappropriate choice of the circuit parameters can lead to significant distortion of the temporal photodetachment signal, leading to large measurement errors of the negative ion density and temperature.

Bryant, P. M.; Bradley, J. W.

2013-02-01

370

Searching for an optimum solution to the Bangladesh arsenic crisis.  

PubMed

Searching for an optimum solution to the Bangladesh arsenic crisis: Thirty years ago Bangladesh experienced very high levels of infant and child mortality, much of it due to water-borne disease in deltaic conditions where surface water was highly polluted. In what appeared to be one of the great public health achievements, 95% of the population were converted to drinking bacteria-free tubewell water from underground aquifers. Recently, it has been shown that perhaps 20% of this water is arsenic contaminated and alternatives to tubewell water have been sought. This paper reports on two national surveys collaboratively carried out in 2000 by the Health Transition Centre, Australian National University and Mitra and Associates, Dhaka: A census of tubewells and a household survey of tubewell use and arseniosis. The study found that the tubewell revolution has been promoted not only by health considerations but also by the demand for a household water facility and the desire by women to reduce workloads associated with using surface water. Because of this, and because the population had absorbed the message about safe tubewell water, it is argued that the movement away from the use of tubewell water should be as limited as possible, even if this means using safe tubewells which are often found in the neighbourhood. To enable such a move the most urgent need is not changing the source of water but comprehensive national water testing providing essential information to households about which wells are safe and which are not. PMID:12697199

Caldwell, Bruce K; Caldwell, John C; Mitra, S N; Smith, Wayne

2003-05-01

371

Optimum Heart Rate to Minimize Pulsatile External Cardiac Power  

NASA Astrophysics Data System (ADS)

The workload on the left ventricle is composed of steady and pulsatile components. Clinical investigations have confirmed that an abnormal pulsatile load plays an important role in the pathogenesis of left ventricular hypertrophy (LVH) and progression of LVH to congestive heart failure (CHF). The pulsatile load is the result of the complex dynamics of wave propagation and reflection in the compliant arterial vasculature. We hypothesize that aortic waves can be optimized to reduce the left ventricular (LV) pulsatile load. We used an in-vitro experimental approach to investigate our hypothesis. A unique hydraulic model was used for in-vitro experiments. This model has physical and dynamical properties similar to the heart-aorta system. Different compliant models of the artificial aorta were used to test the hypothesis under various aortic rigidities. Our results indicate that: i) there is an optimum heart rate that minimizes LV pulsatile power (this is in agreement with our previous computational study); ii) introducing an extra reflection site at the specific location along the aorta creates constructive wave conditions that reduce the LV pulsatile power.

Pahlevan, Niema; Gharib, Morteza

2011-11-01

372

Fuel optimum low-thrust elliptic transfer using numerical averaging  

NASA Astrophysics Data System (ADS)

Low-thrust electric propulsion is increasingly being used for spacecraft missions primarily due to its high propellant efficiency. As a result, a simple and fast method for low-thrust trajectory optimization is of great value for preliminary mission planning. However, few low-thrust trajectory tools are appropriate for preliminary mission design studies. The method presented in this paper provides quick and accurate solutions for a wide range of transfers by using numerical orbital averaging to improve solution convergence and include orbital perturbations. Thus, preliminary trajectories can be obtained for transfers which involve many revolutions about the primary body. This method considers minimum fuel transfers using first-order averaging to obtain the fuel optimum rates of change of the equinoctial orbital elements in terms of each other and the Lagrange multipliers. Constraints on thrust and power, as well as minimum periapsis, are implemented and the equations are averaged numerically using a Gausian quadrature. The use of numerical averaging allows for more complex orbital perturbations to be added in the future without great difficulty. The effects of zonal gravity harmonics, solar radiation pressure, and thrust limitations due to shadowing are included in this study. The solution to a transfer which minimizes the square of the thrust magnitude is used as a preliminary guess for the minimum fuel problem, thus allowing for faster convergence to a wider range of problems. Results from this model are shown to provide a reduction in propellant mass required over previous minimum fuel solutions.

Tarzi, Zahi; Speyer, Jason; Wirz, Richard

2013-05-01

373

Optimum dimensions of power solenoids for magnetic suspension  

NASA Technical Reports Server (NTRS)

Design optimization of power solenoids for controllable and stabilizable magnetic suspensions with force compensation in a wind tunnel is shown. It is assumed that the model of a levitating body is a sphere of ferromagnetic material with constant magnetic permeability. This sphere, with a radius much smaller than its distance from the solenoid above, is to be maintained in position on the solenoid axis by balance of the vertical electromagnetic force and the force of gravitation. The necessary vertical (axial) force generated by the solenoid is expressed as a function of relevant system dimensions, solenoid design parameters, and physical properties of the body. Three families of curves are obtained which depict the solenoid power for a given force as a function of the solenoid length with either outside radius or inside radius as a variable parameter and as a function of the outside radius with inside radius as a variable parameter. The curves indicate the optimum solenoid length and outside radius, for minimum power, corresponding to a given outside radius and inside radius, respectively.

Kaznacheyev, B. A.

1985-01-01

374

Evolution of the optimum bidirectional (+/- biphasic) wave for defibrillation.  

PubMed

Introduction of the asymmetric bidirectional (+/- biphasic) current waveform has made it possible to achieve ventricular defibrillation with less energy and current than are needed with a unidirectional (monophasic) waveform. The symmetrical bidirectional (sinusoidal) waveform was used for the first human-heart defibrillation. Subsequent studies employed the underdamped and overdamped sine waves, then the trapezoidal (monophasic) wave. Studies were then undertaken to investigate the benefit of adding a second identical and inverted wave; little success rewarded these efforts until it was discovered that the second inverted wave needed to be much less in amplitude to lower the threshold for defibrillation. However, there is no physiologic theory that explains the mechanism of action of the bidirectional wave, nor does any theory predict the optimum amplitude and time dimensions for the second inverted wave. The authors analyze the research that shows that the threshold defibrillation energy is lowest when the charge in the second, inverted phase is slightly more than a third of that in the first phase. An ion-flux, spatial-K+ summation hypothesis is presented that shows the effect on myocardial cells of adding the second inverted current pulse. PMID:10690435

Geddes, L A; Havel, W

2000-01-01

375

Optimum contribution selection for conserved populations with historic migration  

PubMed Central

Background In recent decades, local varieties of domesticated animal species have been frequently crossed with economically superior breeds which has resulted in considerable genetic contributions from migrants. Optimum contribution selection by maximizing gene diversity while constraining breeding values of the offspring or vice versa could eventually lead to the extinction of local breeds with historic migration because maximization of gene diversity or breeding values would be achieved by maximization of migrant contributions. Therefore, other objective functions are needed for these breeds. Results Different objective functions and side constraints were compared with respect to their ability to reduce migrant contributions, to increase the genome equivalents originating from native founders, and to conserve gene diversity. Additionally, a new method for monitoring the development of effective size for breeds with incomplete pedigree records was applied. Approaches were compared for Vorderwald cattle, Hinterwald cattle, and Limpurg cattle. Migrant contributions could be substantially decreased for these three breeds, but the potential to increase the native genome equivalents is limited. Conclusions The most promising approach was constraining migrant contributions while maximizing the conditional probability that two alleles randomly chosen from the offspring population are not identical by descent, given that both descend from native founders. PMID:23153196

2012-01-01

376

Generation of optimum pseudorandom signals for respiratory impedance measurements.  

PubMed

Spontaneous breathing may impair the reliability of forced oscillatory impedance estimates at low frequencies, especially when the oscillatory power is distributed among many frequency values. Since the amplitude of the external forcing is limited to avoid non-linearities, it is suggested that the total energy of a composite electrical signal driving the loudspeaker be maximized at a given amplitude by finding the optimum phase relationships of the signal components, and that the low-frequency components increase in energy at the expense of the less disturbed high-frequency region. In healthy children and adults and in obstructed patients, the coherences and the coefficients of variation of the respiratory system impedance (Zrs) at 2 and 3 Hz were studied in the case of three test signals of 2-15 Hz bandwidth. Signals T1 and T2 had a flat power spectrum, whereas the components of T3 decreased sharply between 2 and 5 Hz; T1 was generated by simple random selection of phase angles, while optimization for maximum energy was done for T2 and T3. Optimization alone (T2) increased the reliability of the Zrs estimates at all frequencies, whereas enhancement of the low-frequency power (T3) resulted in a radical improvement of the estimates at 2 and 3 Hz, without loss in reliability at higher frequencies. PMID:2312191

Daróczy, B; Hantos, Z

1990-02-01

377

Optimum cooking conditions for shrimp and Atlantic salmon.  

PubMed

The quality and safety of a cooked food product depends on many variables, including the cooking method and time-temperature combinations employed. The overall heating profile of the food can be useful in predicting the quality changes and microbial inactivation occurring during cooking. Mathematical modeling can be used to attain the complex heating profile of a food product during cooking. Studies were performed to monitor the product heating profile during the baking and boiling of shrimp and the baking and pan-frying of salmon. Product color, texture, moisture content, mass loss, and pressed juice were evaluated during the cooking processes as the products reached the internal temperature recommended by the FDA. Studies were also performed on the inactivation of Salmonella cocktails in shrimp and salmon. To effectively predict inactivation during cooking, the Bigelow, Fermi distribution, and Weibull distribution models were applied to the Salmonella thermal inactivation data. Minimum cooking temperatures necessary to destroy Salmonella in shrimp and salmon were determined. The heating profiles of the 2 products were modeled using the finite difference method. Temperature data directly from the modeled heating profiles were then used in the kinetic modeling of quality change and Salmonella inactivation during cooking. The optimum cooking times for a 3-log reduction of Salmonella and maintaining 95% of quality attributes are 100, 233, 159, 378, 1132, and 399 s for boiling extra jumbo shrimp, baking extra jumbo shrimp, boiling colossal shrimp, baking colossal shrimp, baking Atlantic salmon, and pan frying Atlantic Salmon, respectively. PMID:23387897

Brookmire, Lauren; Mallikarjunan, P; Jahncke, M; Grisso, R

2013-02-01

378

Optimum Conditions for Artificial Fruiting Body Formation of Cordyceps cardinalis.  

PubMed

Stromatal fruiting bodies of Cordyceps cardinalis were successfully produced in cereals. Brown rice, German millet and standard millet produced the longest-length of stromata, followed by Chinese pearl barley, Indian millet, black rice and standard barley. Oatmeal produced the shortest-length of fruiting bodies. Supplementation of pupa and larva to the grains resulted in a slightly enhanced production of fruiting bodies; pupa showing better production than larva. 50~60 g of brown rice and 10~20 g of pupa mixed with 50~60 mL of water in 1,000 mL polypropylene (PP) bottle was found to be optimum for fruiting body production. Liquid inoculation of 15~20 mL per PP bottle produced best fruiting bodies. The optimal temperature for the formation of fruiting bodies was 25?, under conditions of continuous light. Few fruiting bodies were produced under the condition of complete darkness, and the fresh weight was considerable low, compared to that of light condition. PMID:23956641

Kim, Soo-Young; Shrestha, Bhushan; Sung, Gi-Ho; Han, Sang-Kuk; Sung, Jae-Mo

2010-06-01

379

A study on the optimum fast neutron flux for boron neutron capture therapy of deep-seated tumors.  

PubMed

High-energy neutrons, named fast neutrons which have a number of undesirable biological effects on tissue, are a challenging problem in beam designing for Boron Neutron Capture Therapy, BNCT. In spite of this fact, there is not a widely accepted criterion to guide the beam designer to determine the appropriate contribution of fast neutrons in the spectrum. Although a number of researchers have proposed a target value for the ratio of fast neutron flux to epithermal neutron flux, it can be shown that this criterion may not provide the optimum treatment condition. This simulation study deals with the determination of the optimum contribution of fast neutron flux in the beam for BNCT of deep-seated tumors. Since the dose due to these high-energy neutrons damages shallow tissues, delivered dose to skin is considered as a measure for determining the acceptability of the designed beam. To serve this purpose, various beam shaping assemblies that result in different contribution of fast neutron flux are designed. The performances of the neutron beams corresponding to such configurations are assessed in a simulated head phantom. It is shown that the previously used criterion, which suggests a limit value for the contribution of fast neutrons in beam, does not necessarily provide the optimum condition. Accordingly, it is important to specify other complementary limits considering the energy of fast neutrons. By analyzing various neutron spectra, two limits on fast neutron flux are proposed and their validity is investigated. The results show that considering these limits together with the widely accepted IAEA criteria makes it possible to have a more realistic assessment of sufficiency of the designed beam. Satisfying these criteria not only leads to reduction of delivered dose to skin, but also increases the advantage depth in tissue and delivered dose to tumor during the treatment time. The Monte Carlo Code, MCNP-X, is used to perform these simulations. PMID:25479433

Rasouli, Fatemeh S; Masoudi, S Farhad

2015-02-01

380

Wilson loops in minimal surfaces  

SciTech Connect

The AdS/CFT correspondence suggests that the Wilson loop of the large N gauge theory with N = 4 supersymmetry in 4 dimensions is described by a minimal surface in AdS{sub 5} x S{sup 5}. The authors examine various aspects of this proposal, comparing gauge theory expectations with computations of minimal surfaces. There is a distinguished class of loops, which the authors call BPS loops, whose expectation values are free from ultra-violet divergence. They formulate the loop equation for such loops. To the extent that they have checked, the minimal surface in AdS{sub 5} x S{sup 5} gives a solution of the equation. The authors also discuss the zig-zag symmetry of the loop operator. In the N = 4 gauge theory, they expect the zig-zag symmetry to hold when the loop does not couple the scalar fields in the supermultiplet. They will show how this is realized for the minimal surface.

Drukker, Nadav; Gross, David J.; Ooguri, Hirosi

1999-04-27

381

Rogowski Loop design for NSTX  

SciTech Connect

The Rogowski Loop is one of the most basic diagnostics for tokamak operations. On the National Spherical Torus Experiment (NSTX), the plasma current Rogowski Loop had the constraints of the very limited space available on the center stack, 5,000 volt isolation, flexibility requirements as it remained a part of the Center Stack assembly after the first phase of operation, and a +120 C temperature requirement. For the second phase of operation, four Halo Current Rogowski Loops under the Center Stack tiles will be installed having +600 C and limited space requirements. Also as part of the second operational phase, up to ten Rogowski Loops will installed to measure eddy currents in the Passive Plate support structures with +350 C, restricted space, and flexibility requirements. This presentation will provide the details of the material selection, fabrication techniques, testing, and installation results of the Rogowski Loops that were fabricated for the high temperature operational and bakeout requirements, high voltage isolation requirements, and the space and flexibility requirements imposed upon the Rogowski Loops. In the future operational phases of NSTX, additional Rogowski Loops could be anticipated that will measure toroidal plasma currents in the vacuum vessel and in the Passive Plate assemblies.

McCormack, B.; Kaita, R.; Kugel, H.; Hatcher, R.

2000-01-06

382

An Experimental Investigation of Miniature Loop Heat Pipe with Flat Evaporator  

Microsoft Academic Search

This paper specifically addresses the thermal characteristics of the miniature loop heat pipe (mLHP) with flat disk shaped evaporator for the thermal control of the compact electronic devices. The loop was made of stainless steel with sintered nickel wick and ammonia as the working fluid. Detail study was conducted on the start-up reliability of the mLHP and the operating characteristics

Dongxing Gai; Wei Liu; Zhichun Liu; Jinguo Yang

2009-01-01

383

Numerical simulation of mold shape’s influence on NbTi cold-pressing superconducting joint  

NASA Astrophysics Data System (ADS)

The cold-pressing welding methods are employed to fabricate joints between NbTi multi-filamentary conductors, and a series of joints are made with the molds of different shapes for nuclear magnetic resonance (NMR) magnet applications. The Abaqus-Explicit method was used to do a quasi-static analysis of the cold-pressing welding process. In the simulation, we analyzed four molds with different shapes: plate mold, cap mold, square mold, and radial compression. The simulation shows that the deformation of filaments is the most uniform in the case of radial compression and the square mold is the optimum one for decreasing joint resistance.

Zhou, Feng; Cheng, Junsheng; Dai, Yinming; Wang, Qiuliang; Yan, Luguang

2014-03-01

384

Optimum shape of a Kirkpatrick-Baez X-ray reflector supported at discrete points for on-axis performance  

NASA Technical Reports Server (NTRS)

A method is proposed for optimizing the on-axis resolution of a Kirkpatrick-Baez reflecting element. The proposed procedure provides a way to determine the location of each of the 11,200 support points (175 different points plus repeats) by using a computer-assisted structural-optical software package. This automated procedure will make it possible to determine the optical characteristics of an entire telescope module consisting of seventy mirrors.

Cohen, L. M.

1981-01-01

385

Linear optimum trim solution for aircraft with three longitudinal control effectors  

NASA Technical Reports Server (NTRS)

A simple and fast linear optimum method for trimming aircraft with a combination of three longitudinal aerodynamic or propulsive control effectors is developed, with application to preliminary design or in-flight scheduling. A Lagrangian formulation is used to determine the longitudinal load distribution which minimizes trim drag. Trim drag results obtained with the linear optimum method are similar to those obtained with a nonlinear optimum method, and significant trim drag reductions are found using either optimum method, in comparison with results obtained using various ad hoc methods.

Goodrich, Kenneth H.; Sliwa, Steven M.

1987-01-01

386

Digital phase-locked loop  

NASA Technical Reports Server (NTRS)

An digital phase-locked loop is provided for deriving a loop output signal from an accumulator output terminal. A phase detecting exclusive OR gate is fed by the loop digital input and output signals. The output of the phase detector is a bi-level digital signal having a duty cycle indicative of the relative phase of the input and output signals. The accumulator is incremented at a first rate in response to a first output level of the phase detector and at a second rate in response to a second output level of the phase detector.

Cliff, R. A. (inventor)

1975-01-01

387

Loop-deformed Poincaré algebra  

E-print Network

In this essay we present evidence suggesting that loop quantum gravity leads to deformation of the local Poincar\\'e algebra within the limit of high energies. This deformation is a consequence of quantum modification of effective off-shell hypersurface deformation algebra. Surprisingly, the form of deformation suggests that the signature of space-time changes from Lorentzian to Euclidean at large curvatures. We construct particular realization of the loop-deformed Poincar\\'e algebra and find that it can be related to curved momentum space, which indicates the relationship with recently introduced notion of relative locality. The presented findings open a new way of testing loop quantum gravity effects.

Jakub Mielczarek

2013-04-08

388

Closed loop obstruction: pictorial essay.  

PubMed

Closed loop obstruction occurs when a segment of bowel is incarcerated at two contiguous points. The diagnosis is based on multiple transitional zones. The incarcerated loops appear in U or C form or present a radial layout around the location of the obstruction. It's very important to specify the type of obstruction because, in patients with simple bowel obstruction, a conservative approach is often advised. On the other hand, a closed loop obstruction immediately requires a surgical approach because of its high morbidity and the risk of death in case of a late diagnosis. PMID:24290342

Mbengue, A; Ndiaye, A; Soko, T O; Sahnoun, M; Fall, A; Diouf, C T; Régent, D; Diakhaté, I C

2015-02-01

389

Magnetic Reconnection between Small-scale Loops Observed with the New Vacuum Solar Telescope  

NASA Astrophysics Data System (ADS)

Using the high tempo-spatial resolution H? images observed with the New Vacuum Solar Telescope, we report solid observational evidence of magnetic reconnection between two sets of small-scale, anti-parallel loops with an X-shaped topology. The reconnection process contains two steps: a slow step with a duration of more than several tens of minutes, and a rapid step lasting for only about three minutes. During the slow reconnection, two sets of anti-parallel loops gradually reconnect, and new loops are formed and stacked together. During the rapid reconnection, the anti-parallel loops approach each other quickly, and then rapid reconnection takes place, resulting in the disappearance of the former loops. In the meantime, new loops are formed and separate. The region between the approaching loops is brightened, and the thickness and length of this region are determined to be about 420 km and 1.4 Mm, respectively. During the rapid reconnection process, obvious brightenings at the reconnection site and apparent material ejections outward along reconnected loops are observed. These observed signatures are consistent with predictions by reconnection models. We suggest that the successive slow reconnection changes the conditions around the reconnection site and triggers instabilities, thus leading to the rapid approach of the anti-parallel loops and resulting in the rapid reconnection.

Yang, Shuhong; Zhang, Jun; Xiang, Yongyuan

2015-01-01

390

Comprehensive modelling of dynamic hysteresis loops in the rolling and transverse directions for transformer laminations  

NASA Astrophysics Data System (ADS)

Magnetic properties of grain-oriented materials are affected by hysteresis, anisotropy and dynamic effects. The attempts to describe dynamic hysteresis loops are usually limited to the rolling direction (RD). On the other hand, modelling of magnetic properties for the transverse direction (TD) is important for numerical analysis of core-joints and corner regions in transformers. For this direction, hysteresis loops reveal complex shapes particularly for dynamic magnetization conditions. This paper presents a comprehensive approach for modelling of dynamic hysteresis loops in RD and TD. This work uses the magnetic viscosity-based approach, which is able to describe irregular widening of dynamic loops. The loss separation scheme is also considered for both principal directions. Variations of loss components with frequency for both directions are discussed. The computed dynamic loops in RD and TD are in a close agreement with experimental ones.

Baghel, A. P. S.; Gupta, A.; Chwastek, K.; Kulkarni, S. V.

2015-04-01

391

Stability and bifurcation of a soap film spanning an elastic loop  

E-print Network

The Euler--Plateau problem, proposed by \\cite{gm}, concerns a soap film spanning a flexible loop. The shapes of the film and the loop are determined by the interactions between the two components. In the present work, the Euler--Plateau problem is reformulated to yield a boundary-value problem for a vector field that parameterizes both the spanning surface and the bounding loop. Using the first and second variations of the relevant free-energy functional, detailed bifurcation and stability analyses are performed. For spanning surface with energy density $\\sigma$ and a bounding loop with length $2\\pi R$ and bending rigidity $a$, the first bifurcation, during which the spanning surface remains flat but the bounding loop becomes noncircular, occurs at $\\sigma R^3/a=3$, confirming a result obtained previously via an energy comparison. Other bifurcation solution branches, including those emanating from the flat circular solution branch to nonplanar solution branches, are also shown to be unstable.

Yi-chao Chen; Eliot Fried

2013-07-12

392

Picophytoplankton physiology and the microbial loop  

NASA Astrophysics Data System (ADS)

Physiological observations are needed for a better understanding of the complexity of marine ecosystem processes. This information is important for a better model formulation and parameterisation to identify the consequences of, and feedbacks to, global change and to make future projections. Picophytoplankton form the smallest component of the phytoplankton community (˜ 3?m) and show a substantial contribution to phytoplankton biomass in oligotrophic oceans. Here they also have an important function as primary producers in the microbial loop. They include cyanobacteria, represented by Prochlorococcus and Synechococcus, and picoeukaryotes. The aim of this project is to achieve a better representation of picophytoplankton in the global biogeochemical model PlankTOM 10. PlankTOM 10 simplifies the complex ecosystem into 10 conceptual groups also known as plankton functional types (PFTs). These groups of organisms are defined by physiological and biochemical parameters (6 of phytoplankton, 3 of zooplankton and 1 of bacteria). Furthermore, the question will be addressed, whether picophytoplankton are typical K-strategists with low minimum nutrient and high maximum chlorophyll quota relative to carbon, or by having superior nutrient uptake kinetics and light harvesting (high ?Chl). Laboratory experiments showed that the smaller picoprokaryotes respond faster to increasing light intensities than their picoeukaryotic counterpart. Preliminary data show that the initial slope of the photosynthesis vs. irradiance curve (?Chl) of picoprokaryotes is about 1.5 times higher than of picoeukaryotes. This is consistent with their common distribution at the deep chlorophyll maximum. The maximum chlorophyll quota are not significantly different. Temperature experiments confirmed that the maximum growth rates of picophytoplankton at the optimum temperature (0.47 ± 0.17 d-1 for prokaryotes and 1.05 ± 0.47 d-1 for eukaryotes) are significantly lower than of diatoms (1.57 ± 0.73 d-1, Chollet et al. in prep.) and not significantly different from coccolithophores (0.68 ± 0.10 d-1, Buitenhuis et al. 2008), consistent with the characterisation of picophytoplanton as K-strategists. Their optimum temperatures were found to be 22.7 ± 2.0 ° C for prokaryotes and 23.6 ± 3.1 ° C for eukaryotes. Nutrient limitation experiments will be conducted to characterize the nutrient uptake and elemental composition of picophytoplankton. Finally the results of all experiments will then be used to improve the representation of picophytoplankton in PlankTOM10, evaluated against a recently compiled global database of picophytoplankton biomass.

Stawiarski, Beate

2013-04-01

393

Two-channel Costas loop tracking performance for UQPSK signals with arbitrary data formats  

NASA Astrophysics Data System (ADS)

Previous results on the tracking performance of two-channel Costas-type carrier synchronization loops are generalized and corrected, in order that they may be applied to several mixed-format cases. In particular, the mean-square phase jitter performance of these loops with active arm filters, synchronous or asynchronous symbol clocks, and arbitrary data formats on the two channels is examined. It is demonstrated that for each case, selection of the channel gain ratio, as motivated by the MAP estimation theory, does not guarantee optimum loop tracking performance: in some instances, a conventional single-channel Costas loop would outperform the two-channel version with the MAP choice of gain ratio. It is suggested that the gain ratio be chosen to directly minimize the mean-square phase tracking jitter which is equivalent to minimizing the loop's 'squaring loss'. This can, in some cases, improve the performance measure, although in all cases, the two-channel loop will still outperform the single-channel version.

Simon, M. K.

1981-09-01

394

Widespread formation of cherts during the early Eocene climate optimum  

NASA Astrophysics Data System (ADS)

Radiolarian cherts in the Tethyan realm of Jurassic age were recently interpreted as resulting from high biosiliceous productivity along upwelling zones in subequatorial paleolatitudes the locations of which were confirmed by revised paleomagnetic estimates. However, the widespread occurrence of cherts in the Eocene suggests that cherts may not always be reliable proxies of latitude and upwelling zones. In a new survey of the global spatiotemporal distribution of Cenozoic cherts in Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) sediment cores, we found that cherts occur most frequently in the Paleocene and early Eocene, with a peak in occurrences at ~50 Ma that is coincident with the time of highest bottom water temperatures of the early Eocene climatic optimum (EECO) when the global ocean was presumably characterized by reduced upwelling efficiency and biosiliceous productivity. Cherts occur less commonly during the subsequent Eocene global cooling trend. Primary paleoclimatic factors rather than secondary diagenetic processes seem therefore to control chert formation. This timing of peak Eocene chert occurrence, which is supported by detailed stratigraphic correlations, contradicts currently accepted models that involve an initial loading of large amounts of dissolved silica from enhanced weathering and/or volcanism in a supposedly sluggish ocean of the EECO, followed during the subsequent middle Eocene global cooling by more vigorous oceanic circulation and consequent upwelling that made this silica reservoir available for enhanced biosilicification, with the formation of chert as a result of biosilica transformation during diagenesis. Instead, we suggest that basin-basin fractionation by deep-sea circulation could have raised the concentration of EECO dissolved silica especially in the North Atlantic, where an alternative mode of silica burial involving widespread direct precipitation and/or absorption of silica by clay minerals could have been operative in order to maintain balance between silica input and output during the upwelling-deficient conditions of the EECO. Cherts may therefore not always be proxies of biosiliceous productivity associated with latitudinally focused upwelling zones.

Muttoni, G.; Kent, D. V.

2007-12-01

395

Investigating the Optimum Size of DIVA's Dispersed Images  

NASA Astrophysics Data System (ADS)

The DIVA satellite is planned to be launched in 2004. It is primarily an all-sky survey astrometric mission but will also obtain spectrophotometric information for about 13 million stars. Constructional studies foresee a grating system yielding a dispersion of ~=200nm/mm on the focal plane. For reasons of astrometry there will be no cross dispersion resulting in strong overlapping of the first to third spectral orders. The optimum window size of these dispersed images to be cut out from the focal plane's continous data stream was investigated. This size determines the data rate and limiting visual magnitude, thus determining the satellite's overall abilities. The simulations of these spectrophotometric windows were performed with the software tool from Ralf Scholz using stellar spectra with full possible wavelength coverage of 200 to 1200 nm as input. Dispersed noisy images for many spectral types and relevant visual magnitudes from 10 to 14 mag were modeled. S/N studies in both directions (scan and cross-scan direction) were performed using standard photometric tools. Special attention was paid to the overlapping region of the different orders, containing a maximum of stellar information. Requiring a minimum S/N of 5, the suggestion for the final window to be cut out is maximum 7 pixel in scan direction and 80 to 120 effective pixel in the direction of dispersion. This range will be narrowed using results from the routines to extract stellar parameters (neural network, comparison with model spectra, ect.). The corresponding data rates will be in the range of 37 to 55 Kbytes per second.

de Boer, K. S.; Hilker, M.; Kaempf, T.; Reif, K.; Willemsen, P.

396

Optimum place of piezoelectric material in the piezoactuator design  

NASA Astrophysics Data System (ADS)

Piezoelectric actuators offer significant promise in a wide range of applications. The piezoelectric actuators considered in this work essentially consist of a flexible structure actuated by piezoceramics that must generate output displacement and force at a certain specified point of the domain and direction. The flexible structure acts as a mechanical transformer by amplifying and changing the direction of piezoceramics output displacements. The design of these piezoelectric actuators are complex and a systematic design method, such as topology optimization has been successfully applied in the latest years, with appropriate formulation of the optimization problem to obtain optimized designs. However, in these previous design formulations, piezoceramics position are usually kept fixed in the design domain and only the flexible structure is designed by distributing only some non-piezoelectric material (Aluminum, for example). This imposes a constraint in the position of piezoelectric material in the optimization problem limiting the optimality of the solution. Thus, in this work, a formulation that allows the simultaneous search for an optimal topology of a flexible structure as well as the optimal positions of the piezoceramics in the design domain, to achieve certain specified actuation movements, will be presented. This can be achieved by allowing the simultaneous distribution of non-piezoelectric and piezoelectric material in the design domain. The optimization problem is posed as the design of a flexible structure together with optimum positions of piezoelectric material that maximizes output displacements or output forces in a certain specified direction and point of the domain. The method is implemented based on the SIMP material model where fictitious densities are interpolated in each finite element, providing a continuum material distribution in the domain. Presented examples are limited to two-dimensional models, once most of the applications for such piezoelectric actuators are planar devices.

Carbonari, Ronny C.; Nishiwaki, Shinji; Silva, Emílio C. N.

2006-03-01

397

Evolution and dynamics of cusped light-like Wilson loops (Hadron 2013)  

E-print Network

We address a connection between the energy evolution of the polygonal light-like Wilson exponentials and the geometry of the loop space with the gauge invariant Wilson loops of a variety of shapes being the fundamental degrees of freedom. The renormalization properties and the differential area evolution of these Wilson polygons are studied by making use of the universal Schwinger quantum dynamical approach. We discuss the appropriateness of the dynamical differential equations in the loop space to the study of the energy evolution of the collinear and transverse-momentum dependent parton distribution functions.

Frederik F. Van der Veken

2014-05-15

398

Numerical evaluation of loop integrals  

E-print Network

We present a new method for the numerical evaluation of arbitrary loop integrals in dimensional regularization. We first derive Mellin-Barnes integral representations and apply an algorithmic technique, based on the Cauchy theorem, to extract the divergent parts in the epsilon->0 limit. We then perform an epsilon-expansion and evaluate the integral coefficients of the expansion numerically. The method yields stable results in physical kinematic regions avoiding intricate analytic continuations. It can also be applied to evaluate both scalar and tensor integrals without employing reduction methods. We demonstrate our method with specific examples of infrared divergent integrals with many kinematic scales, such as two-loop and three-loop box integrals and tensor integrals of rank six for the one-loop hexagon topology.

Charalampos Anastasiou; Alejandro Daleo

2006-04-17

399

Integrated optical phase locked loop.  

SciTech Connect

A silicon photonics based integrated optical phase locked loop is utilized to synchronize a 10.2 GHz voltage controlled oscillator with a 509 MHz mode locked laser, achieving 32 fs integrated jitter over 300 kHz bandwidth.

Lentine, Anthony L.; Kim, Jungwon (Massachusetts Institute of Technology, Cambridge, MA); Trotter, Douglas Chandler; DeRose, Christopher T.; Kartner, Franz X. (Massachusetts Institute of Technology, Cambridge, MA); Byun, Hyunil (Massachusetts Institute of Technology, Cambridge, MA); Nejadmalayeri, Amir H. (Massachusetts Institute of Technology, Cambridge, MA); Watts, Michael R.; Zortman, William A.

2010-12-01

400

Integrated optical phase locked loop  

Microsoft Academic Search

A silicon photonics based integrated optical phase locked loop is utilized to synchronize a 10.2 GHz voltage controlled oscillator with a 509 MHz mode locked laser, achieving 32 fs integrated jitter over 300 kHz bandwidth.

Anthony L. Lentine; Jungwon Kim; Douglas Chandler Trotter; Christopher T. DeRose; Franz X. Kartner; Hyunil Byun; Amir H. Nejadmalayeri; Michael R. Watts; William A. Zortman

2010-01-01

401

Automatic blocking of nested loops  

NASA Technical Reports Server (NTRS)

Blocked algorithms have much better properties of data locality and therefore can be much more efficient than ordinary algorithms when a memory hierarchy is involved. On the other hand, they are very difficult to write and to tune for particular machines. The reorganization is considered of nested loops through the use of known program transformations in order to create blocked algorithms automatically. The program transformations used are strip mining, loop interchange, and a variant of loop skewing in which invertible linear transformations (with integer coordinates) of the loop indices are allowed. Some problems are solved concerning the optimal application of these transformations. It is shown, in a very general setting, how to choose a nearly optimal set of transformed indices. It is then shown, in one particular but rather frequently occurring situation, how to choose an optimal set of block sizes.

Schreiber, Robert; Dongarra, Jack J.

1990-01-01

402

Bending of the looping heart: differential growth revisited.  

PubMed

In the early embryo, the primitive heart tube (HT) undergoes the morphogenetic process of c-looping as it bends and twists into a c-shaped tube. Despite intensive study for nearly a century, the physical forces that drive looping remain poorly understood. This is especially true for the bending component, which is the focus of this paper. For decades, experimental measurements of mitotic rates had seemingly eliminated differential growth as the cause of HT bending, as it has commonly been thought that the heart grows almost exclusively via hyperplasia before birth and hypertrophy after birth. Recently published data, however, suggests that hypertrophic growth may play a role in looping. To test this idea, we developed finite-element models that include regionally measured changes in myocardial volume over the HT. First, models based on idealized cylindrical geometry were used to simulate the bending process in isolated hearts, which bend without the complicating effects of external loads. With the number of free parameters in the model reduced to the extent possible, stress and strain distributions were compared to those measured in embryonic chick hearts that were isolated and cultured for 24 h. The results show that differential growth alone yields results that agree reasonably well with the trends in our data, but adding active changes in myocardial cell shape provides closer quantitative agreement with stress measurements. Next, the estimated parameters were extrapolated to a model based on realistic 3D geometry reconstructed from images of an actual chick heart. This model yields similar results and captures quite well the basic morphology of the looped heart. Overall, our study suggests that differential hypertrophic growth in the myocardium (MY) is the primary cause of the bending component of c-looping, with other mechanisms possibly playing lesser roles. PMID:24509638

Shi, Yunfei; Yao, Jiang; Xu, Gang; Taber, Larry A

2014-08-01

403

Affective loop experiences: designing for interactional embodiment.  

PubMed

Involving our corporeal bodies in interaction can create strong affective experiences. Systems that both can be influenced by and influence users corporeally exhibit a use quality we name an affective loop experience. In an affective loop experience, (i) emotions are seen as processes, constructed in the interaction, starting from everyday bodily, cognitive or social experiences; (ii) the system responds in ways that pull the user into the interaction, touching upon end users' physical experiences; and (iii) throughout the interaction the user is an active, meaning-making individual choosing how to express themselves-the interpretation responsibility does not lie with the system. We have built several systems that attempt to create affective loop experiences with more or less successful results. For example, eMoto lets users send text messages between mobile phones, but in addition to text, the messages also have colourful and animated shapes in the background chosen through emotion-gestures with a sensor-enabled stylus pen. Affective Diary is a digital diary with which users can scribble their notes, but it also allows for bodily memorabilia to be recorded from body sensors mapping to users' movement and arousal and placed along a timeline. Users can see patterns in their bodily reactions and relate them to various events going on in their lives. The experiences of building and deploying these systems gave us insights into design requirements for addressing affective loop experiences, such as how to design for turn-taking between user and system, how to create for 'open' surfaces in the design that can carry users' own meaning-making processes, how to combine modalities to create for a 'unity' of expression, and the importance of mirroring user experience in familiar ways that touch upon their everyday social and corporeal experiences. But a more important lesson gained from deploying the systems is how emotion processes are co-constructed and experienced inseparable from all other aspects of everyday life. Emotion processes are part of our social ways of being in the world; they dye our dreams, hopes and bodily experiences of the world. If we aim to design for affective interaction experiences, we need to place them into this larger picture. PMID:19884153

Höök, Kristina

2009-12-12

404

Affective loop experiences: designing for interactional embodiment  

PubMed Central

Involving our corporeal bodies in interaction can create strong affective experiences. Systems that both can be influenced by and influence users corporeally exhibit a use quality we name an affective loop experience. In an affective loop experience, (i) emotions are seen as processes, constructed in the interaction, starting from everyday bodily, cognitive or social experiences; (ii) the system responds in ways that pull the user into the interaction, touching upon end users' physical experiences; and (iii) throughout the interaction the user is an active, meaning-making individual choosing how to express themselves—the interpretation responsibility does not lie with the system. We have built several systems that attempt to create affective loop experiences with more or less successful results. For example, eMoto lets users send text messages between mobile phones, but in addition to text, the messages also have colourful and animated shapes in the background chosen through emotion-gestures with a sensor-enabled stylus pen. Affective Diary is a digital diary with which users can scribble their notes, but it also allows for bodily memorabilia to be recorded from body sensors mapping to users' movement and arousal and placed along a timeline. Users can see patterns in their bodily reactions and relate them to various events going on in their lives. The experiences of building and deploying these systems gave us insights into design requirements for addressing affective loop experiences, such as how to design for turn-taking between user and system, how to create for ‘open’ surfaces in the design that can carry users' own meaning-making processes, how to combine modalities to create for a ‘unity’ of expression, and the importance of mirroring user experience in familiar ways that touch upon their everyday social and corporeal experiences. But a more important lesson gained from deploying the systems is how emotion processes are co-constructed and experienced inseparable from all other aspects of everyday life. Emotion processes are part of our social ways of being in the world; they dye our dreams, hopes and bodily experiences of the world. If we aim to design for affective interaction experiences, we need to place them into this larger picture. PMID:19884153

Höök, Kristina

2009-01-01

405

Detection of Oscillating Control Loops  

Microsoft Academic Search

Oscillations in process control loops are a very common problem. Oscillations often indicate a more severe problem than irregular\\u000a variability. The presence of oscillations in a control loop increases the deviations from the setpoint of the process variables,\\u000a thus causing inferior products, larger rejection rates, increased energy consumption and reduced average throughput. There\\u000a are several reasons for oscillations in control

Srinivas Karra; Mohieddine Jelali; M. Nazmul Karim; Alexander Horch

406

Closed loop spray cooling apparatus  

NASA Technical Reports Server (NTRS)

A closed loop apparatus for jet spraying coolant against the back of a radiation target is described. The coolant is circulated through a closed loop with a bubble of inert gas being maintained around the spray. Mesh material is disposed between the bubble and the surface of the liquid coolant which is below the bubble at a predetermined level. In a second arrangement no inert gas is used, the bubble consists of vapor produced when the coolant is sprayed against the target.

Alger, D. L.; Schwab, W. B.; Furman, E. R. (inventors)

1979-01-01

407

Neutrino Factory Mercury Flow Loop  

E-print Network

Neutrino Factory Mercury Flow Loop V. GravesV. Graves C. Caldwell IDS-NF Videoconference March 9, 2010 #12;Flow Loop Review · 1 cm dia nozzle, 20 m/s jet requires 1.57 liter/sec mercury flow (94 2 liter/min 24 9 gpm)mercury flow (94.2 liter/min, 24.9 gpm). · MERIT experiment showed that a pump

McDonald, Kirk

408

Introduction to Loop Quantum Gravity  

E-print Network

The questions I have been asked during the 5th International School on Field Theory and Gravitation, have compelled me to give an account of the premises that I consider important for a beginner's approach to Loop Quantum Gravity. After a description of some general arguments and an introduction to the canonical theory of gravity, I review the background independent approach to quantum gravity, giving only a brief survey of Loop Quantum Gravity.

Simone Mercuri

2010-01-08

409

Brownian Loops and Conformal Fields  

E-print Network

The main topic of these lecture notes is the continuum scaling limit of planar lattice models. One reason why this topic occupies an important place in the theory of probability and mathematical statistical physics is that scaling limits provide the link between statistical mechanics and (Euclidean) field theory. In order to explain the main ideas behind the concept of scaling limit, I will focus on a "toy" model that exhibits the typical behavior of statistical mechanical models at and near the critical point. This model, known as the random walk loop soup, is actually interesting in its own right. It can be described as a Poissonian ensemble of lattice loops, or a lattice gas of loops since it fits within the ideal gas framework of statistical mechanics. After introducing the model and discussing some interesting connections with the discrete Gaussian free field, I will present some results concerning its scaling limit, which leads to a Poissonian ensemble of continuum loops known as the Brownian loop soup. The latter was introduced by Lawler and Werner and is a very interesting object with connections to the Schramm-Loewner Evolution and various models of statistical mechanics. In the second part of the lectures, I will use the Brownian loop soup to construct a family of functions that behave like correlation functions of a conformal field. I will then use these functions and their derivation to introduce the concept of conformal field and to explore the connection between scaling limits and conformal fields.

Federico Camia

2015-01-20

410

Application of digital pulse shaping by least squares method to ultrasonic signals in composites  

NASA Technical Reports Server (NTRS)

For ultrasonic testing in composites, a signal processing tool is identified that can significantly enhance the sharpness of ultrasonic waveforms and provide clearer pictures of the nature of the material flaw. The technique artificially improves the resolution of the system to discrete events by pulse shaping the measured waveform based on the signal from a reference. The optimum pulse shape operator is determined from a least-squares method in the z-domain.

Kishoni, D.

1985-01-01

411

Optimum compression to ventilation ratios in CPR under realistic, practical conditions: a physiological and mathematical analysis  

Microsoft Academic Search

Objective: To develop and evaluate a practical formula for the optimum ratio of compressions to ventilations in cardiopulmonary resuscitation (CPR). The optimum value of a variable is that for which a desired result is maximized. Here the desired result is assumed to be either oxygen delivery to peripheral tissues or a combination of oxygen delivery and waste product removal. Method:

Charles F. Babbs; Karl B. Kern

2002-01-01

412

Some optimum parameters of golay detector of infra-red radiation  

Microsoft Academic Search

The relation for the sensitivity of the pneumatic detector based on the analysis of the thermal, pneumatic and optical parts of the instrument is derived. From this relation the optimum diameter of the flexible mirror and the optimum gas pressure in the detector cell are calculated.

D. Vavrouch; V. BOthER

1963-01-01

413

THE EFFECT OF RECEIVER DIVERSITY COMBINING ON OPTIMUM ENERGY ALLOCATION AND ENERGY EFFICIENCY  

E-print Network

THE EFFECT OF RECEIVER DIVERSITY COMBINING ON OPTIMUM ENERGY ALLOCATION AND ENERGY EFFICIENCY the total energy · Effect of diversity combining techniques on energy efficiency and energy allocation information yr1 = |h|asx + wr1 Scenario Problem Statement · Optimum energy allocation strategy to minimize

Brown III, Donald R.

414

The Effect of Channel State Information on Optimum Energy Allocation and Energy Efficiency  

E-print Network

The Effect of Channel State Information on Optimum Energy Allocation and Energy Efficiency-- This paper considers the problem of how to efficiently allocate transmission energy in a wire- less. The analysis focuses on optimum energy allocation and energy efficiency for two distinctly different scenarios

Brown III, Donald R.

415

Rotation Angle for the Optimum Tracking of One-Axis Trackers  

SciTech Connect

An equation for the rotation angle for optimum tracking of one-axis trackers is derived along with equations giving the relationships between the rotation angle and the surface tilt and azimuth angles. These equations are useful for improved modeling of the solar radiation available to a collector with tracking constraints and for determining the appropriate motor revolutions for optimum tracking.

Marion, W. F.; Dobos, A. P.

2013-07-01

416

A novel optimum operating point tracker of the solar cell power supply system  

Microsoft Academic Search

When the solar array is used as an input power source, the optimum operating point tracker is often employed to exploit more effectively the solar array as an electric power source and to obtain the maximum electric power at all times even when the light intensity and environmental temperature of the solar array are varied. Usually, the optimum operating point

K. Kobayashi; Hirofumi Matsuo; Yutaka Sekine

2004-01-01

417

Relationship between Optimum Temperatures for Growth and Preferred Temperatures for the Young of Four Fish Species  

Microsoft Academic Search

Optimum temperatures for growth and temperature preference were estimated and compared for young striped bass Morone saxatilis, white perch Morone americana, white catfish Ictalurus catus, and spottail shiner Notropis hudsonius to determine how closely behavioral thermoregulation corresponded to optimal growth temperatures. Differences between the final preferenda and the optimum growth temperatures were less than 2 C. The percentage of preferred

Robert L. Kellogg; James J. Gift

1983-01-01

418

Optimum Design of Micro Bare-Tube Heat Exchanger Tomohisa OKU, Nobuhide KASAGI and Yuji SUZUKI  

E-print Network

2313 Optimum Design of Micro Bare-Tube Heat Exchanger Tomohisa OKU, Nobuhide KASAGI and Yuji SUZUKI, optimum design is made for three types of micro bare-tube heat exchangers, i.e., heater core and radiator@thtlab.t.u-tokyo.ac.jp Micro bare-tube heat exchangers can accomplish high performance and compactness with their simple

Tokyo, University of

419

The Determination of an Optimum Size Cylindrical Handle by Use of Electromyography  

Microsoft Academic Search

An experiment was designed using muscle electromyography to determine if an optimum cylindrical handle size exists. The experiment had two phases. One phase was concerned with an experimental task of gripping a cylindrical handle and performing a simple task routine to evaluate the optimum handle size. The other phase was concerned with a fatigue test utilizing the same cylindrical handles.

M. M. AYOUB; P. LO PRESTI

1971-01-01

420

Shape Preserving Spline Interpolation  

NASA Technical Reports Server (NTRS)

A rational spline solution to the problem of shape preserving interpolation is discussed. The rational spline is represented in terms of first derivative values at the knots and provides an alternative to the spline-under-tension. The idea of making the shape control parameters dependent on the first derivative unknowns is then explored. The monotonic or convex shape of the interpolation data can then be preserved automatically through the solution of the resulting non-linear consistency equations of the spline.

Gregory, J. A.

1985-01-01

421

Shape from interreflections  

Microsoft Academic Search

Shape-from-intensity methods assume that points in a scene are only illuminated by the sources of light. This assumption is valid only when the scene consists of a single convex surface. Most scenes consist of concave surfaces where points reflect light among themselves. In the presence of these interreflections, shape-from-intensity methods produce erroneous (pseudo) estimates of shape and reflectance. This article

Shree K. Nayar; Katsushi Ikeuchi; Takeo Kanade

1991-01-01

422

A controlled pump assembly for spacecraft cooling loops  

NASA Astrophysics Data System (ADS)

The role of thermal-control systems is to maintain the temperature of every item onboard a spacecraft within pre-defined temperature limits, throughout all phases of a space mission, with a minimum resource allocation. This includes, in particular, efficient management of the power dissipated onboard. The trend with both applications spacecraft and space vehicles is one of a continuous increase in the services offered to the users. This implies both an increase in the power produced and dissipated onboard, and the provision of a high degree of operational flexibility, including the possibility to change the power load distribution on the spacecraft quickly and safely. Furthermore, many payloads require a high degree of uniformity and stability in terms of their temperature, or the temperature of the environment in which they operate. All of these requirements point to the use of cooling loops, based on either single- or two-phase fluid operation, as the optimum thermal-management system.

de Parolis, M. N.

423

Free loop spaces in topology and  

E-print Network

Free loop spaces in topology and physics Kathryn Hess What is the space of free loops? Enumeration of geodesics Hochschild and cyclic homology Homological conformal field theories Free loop spaces in topology Meeting of the Edinburgh Mathematical Society Glasgow, 14 November 2008 #12;Free loop spaces in topology

Thévenaz, Jacques

424

Fabrication techniques for superconducting readout loops  

NASA Technical Reports Server (NTRS)

Procedures for the fabrication of superconducting readout loops out of niobium on glass substrates were developed. A computer program for an existing fabrication system was developed. Both positive and negative resist procedures for the production of the readout loops were investigated. Methods used to produce satisfactory loops are described and the various parameters affecting the performance of the loops are analyzed.

Payne, J. E.

1982-01-01

425

Filter for third order phase locked loops  

NASA Technical Reports Server (NTRS)

Filters for third-order phase-locked loops are used in receivers to acquire and track carrier signals, particularly signals subject to high doppler-rate changes in frequency. A loop filter with an open-loop transfer function and set of loop constants, setting the damping factor equal to unity are provided.

Crow, R. B.; Tausworthe, R. C. (inventors)

1973-01-01

426

Palynological Investigation of the Holocene Thermal Optimum in New Zealand  

NASA Astrophysics Data System (ADS)

It has long been assumed in New Zealand (NZ) that the Holocene Thermal Optimum (HTO) occurred at the beginning of the Holocene. Nearly 40 years ago, Hendy and Wilson pioneered the use of 18O/16O composition of calcite in NZ speleothems to reconstruct past climate and in so doing showed an HTO occurring earlier in NZ than in comparable Northern Hemisphere records (Hendy & Wilson,1968). More recent work on NZ speleothems (Williams et al., 2005) corroborates the concept of an early HTO dated between ca 11.7 and 10.6 ka, but there is no definitive description of the event as a NZ-wide phenomenon, no intensive dating of it, nor temperature quantification. Moreover, there is no firm conclusion as to whether it is registered consistently between different proxies and across NZ regions. Until recently, attempts to quantify past climate change from NZ pollen data have been hindered by failure to demonstrate robust relationships between modern pollen assemblages and climate due, it is thought, to strong anthropogenic modification of natural vegetation patterns and steep climatic gradients (Norton et al., 1986). However, as deforestation commenced only ca 700 years ago, and is unambiguously detected in pollen records from throughout NZ, an almost unique opportunity exists to develop pollen-climate transfer functions using pre-human pollen-vegetation sources. McGlone and Wilmshurst have assembled an extensive (138-site) `modern' pollen database, based on ca 700 yr BP pre-deforestation pollen assemblages from peat and lake cores. This now provides a basis for more secure pollen-climate reconstruction than hitherto has been possible. Statistical modelling of the environmental determinants of patterns in the pre-deforestation pollen database indicates the strongest relationship (r2 > 0.8) is with Mean Annual Temperature (MAT) and suggests that this parameter can be reliably reconstructed, with error estimates, from Late Quaternary NZ pollen profiles. We use this database to quantify MAT for a selected range of pollen profiles spanning the last glacial-Holocene interval from across the NZ region. We use the resulting MAT profiles to test the "early HTO hypothesis" (that is, a warming at the beginning of, or even just prior to, the Holocene). As well, we examine the amplitude and spatial uniformity of the HTO and its possible cause. References Hendy CH, Wilson AT. 1968. Nature 219, 48-51. Norton DA, McGlone MS, Wigley TML. 1986. NZJBot 24,331-342. Williams PW et al 2005. EPSL 230, 301-317.

Newnham, R. M.; McGlone, M. S.; Wilmshurst, J. M.

2005-12-01

427

Optimum synthetic-aperture imaging of extended astronomical objects.  

PubMed

In optical aperture-synthesis imaging of stellar objects, different beam combination strategies are used and proposed. Coaxial Michelson interferometers are very common and a homothetic multiaxial interferometer is recently realized in the Large Binocular Telescope. Laboratory experiments have demonstrated the working principles of two new approaches: densified pupil imaging and wide field-of-view (FOV) coaxial imaging using a staircase-shaped mirror. We develop a common mathematical formulation for direct comparison of the resolution and noise sensitivity of these four telescope configurations for combining beams from multiple apertures for interferometric synthetic aperture, wide-FOV imaging. Singular value decomposition techniques are used to compare the techniques and observe their distinct signal-to-noise ratio behaviors. We conclude that for a certain chosen stellar object, clear differences in performance of the imagers are identifiable. PMID:17361290

van der Avoort, Casper; Pereira, Silvania F; Braat, Joseph J M; den Herder, Jan-Willem

2007-04-01

428

Multilayered vesicles prepared by reverse-phase evaporation: liposome structure and optimum solute entrapment  

SciTech Connect

Liposome structure and solute entrapment in multilayered vesicles (MLVs) prepared by reverse-phase evaporation (REV) were studied. MLV-REV vesicles prepared from ether/water emulsions have high entrapment. Entrapment depends on drug, drug concentration, lipid, lipid concentration, and the container used to prepare the vesicles. By use of 300 /sup +/L of aqueous phase and 100 mg of phosphatidylcholine (PC), vesicles prepared in a test tube 25 mm x 175 mm have higher entrapment than vesicles prepared in a 100-mL round-bottom or pear-shaped flask. By use of a test tube, 100 mg of PC, and 300 ..mu..L of aqueous phase containing sucrose (1-50 mg/mL), >90% sucrose entrapment was obtained. Increasing lipid content to 150 mg of PC decreased entrapment to approx.80%. Neutral PC MLV-REV vesicles have optimum entrapment. Mixing negatively charged lipids or cholesterol (CH) with PC to make MLV-REV vesicles results in decreased entrapment compared to using only PC. Preparing vesicles with the solid lipid dipalmitoylphosphatidylcholine (DPPC) or DPPC/CH mixtures results in 30-40% entrapment when diethyl ether is used to make the MLV-REV emulsion. The high entrapment found for MLV vesicles prepared from water/organic solvent emulsions depends on maintaining a core during the process of liposome formation. A method to calculate the fraction of water residing in the liposomes' core is presented and used to compare multilayered vesicles prepared by different processes. X-ray diffraction data demonstrate that a heterogeneous distribution of lipid may exist in multilayered vesicles prepared by the REV process.

Pidgeon, C.; McNeely, S.; Schmidt, T.; Johnson, J.E.

1987-01-13

429

Optimum design of bridges with superelastic-friction base isolators against near-field earthquakes  

NASA Astrophysics Data System (ADS)

The seismic response of a multi-span continuous bridge isolated with novel superelastic-friction base isolator (S-FBI) is investigated under near-field earthquakes. The isolation system consists of a flat steel-Teflon sliding bearing and a superelastic NiTi shape memory alloy (SMA) device. Sliding bearings limit the maximum seismic forces transmitted to the superstructure to a certain value that is a function of friction coefficient of sliding interface. Superelastic SMA device provides restoring capability to the isolation system together with additional damping characteristics. The key design parameters of an S-FBI system are the natural period of the isolated, yielding displacement of SMA device, and the friction coefficient of the sliding bearings. The goal of this study is to obtain optimal values for each design parameter by performing sensitivity analyses of the isolated bridge. First, a three-span continuous bridge is modeled as a two-degrees-of-freedom with S-FBI system. A neuro-fuzzy model is used to capture rate-dependent nonlinear behavior of SMA device. A time-dependent method which employs wavelets to adjust accelerograms to match a target response spectrum with minimum changes on the other characteristics of ground motions is used to generate ground motions used in the simulations. Then, a set of nonlinear time history analyses of the isolated bridge is performed. The variation of the peak response quantities of the isolated bridge is shown as a function of design parameters. Also, the influence of temperature variations on the effectiveness of S-FBI system is evaluated. The results show that the optimum design of the isolated bridge with S-FBI system can be achieved by a judicious specification of design parameters.

Ozbulut, Osman E.; Hurlebaus, Stefan

2010-04-01

430

Aridification in continental Asia after the Middle Eocene Climatic Optimum (MECO)  

NASA Astrophysics Data System (ADS)

Global climate cooling from greenhouse to icehouse conditions occurred across an enigmatic transitional interval during the Eocene epoch characterized by incipient polar ice-sheet formation as well as short-lived warming events, of which the Middle Eocene Climatic Optimum (MECO) is most noticeable. Understanding this critical period requires high-resolution records that are being gathered in marine basins, but are still lacking in the terrestrial realm. Here, we provide a precisely-dated terrestrial record crossing the MECO time interval from the Xining Basin (NW China). We document a rapid aridification step and the onset of obliquity-dominated climate cyclicity indicated by lithofacies and pollen records dated at 40.0 Ma at the base of magnetochron C18n.2n. This shift is concomitant - within error - with the MECO peak warming in Ocean Drilling Program Site 1258 for which we reassessed the magnetostratigraphic age at 40.0 Ma (also at base of magnetochron C18n.2n). The rapidity of the shift observed in the Xining Basin and the region-wide aridification and monsoonal intensification reported around 40 Ma suggests Asian paleoenvironments were responding to global climate changes associated with the MECO. However, the Xining records show only the permanent shift but not the transient peak warming observed in marine MECO records. We thus relate this permanent aridification to occur during the post-MECO cooling. We propose the mechanisms linking global climate to Asian paleoenvironments may be eustatic fluctuations driving the stepwise retreat of the proto-Paratethys epicontinental sea or simply global cooling reducing moisture supply to the continental interior. In any case, Eocene global climate cooling from greenhouse to icehouse conditions seem to have played a primary role in shaping Asian paleoenvironments.

Bosboom, Roderic E.; Abels, Hemmo A.; Hoorn, Carina; van den Berg, Bas C. J.; Guo, ZhaoJie; Dupont-Nivet, Guillaume

2014-03-01

431

Non-uniform sampling SC circuits based on noise-shaping feedback coding  

Microsoft Academic Search

This paper describes a non-uniform sampling technique based on a noise-shaping control loop to digitally program the frequency response of switched-capacitor circuits. The use of noise-shaping modulation results in a beneficial shaping of the low-frequency sampling energy introduced by non-uniform sampling. The technique is able to provide high programmability range and resolution, while reducing the impact on the allowed signal

José L. Ausín; J. Francisco Duque-carrillo; Guido Torelli; Jorge Sánchez Valverde

2003-01-01

432

Offline loop investigation for handwriting analysis.  

PubMed

Resolution of different types of loops in handwritten script presents a difficult task and is an important step in many classic word recognition systems, writer modeling, and signature verification. When processing a handwritten script, a great deal of ambiguity occurs when strokes overlap, merge, or intersect. This paper presents a novel loop modeling and contour-based handwriting analysis that improves loop investigation. We show excellent results on various loop resolution scenarios, including axial loop understanding and collapsed loop recovery. We demonstrate our approach for loop investigation on several realistic data sets of static binary images and compare with the ground truth of the genuine online signal. PMID:19110488

Steinherz, Tal; Doermann, David; Rivlin, Ehud; Intrator, Nathan

2009-02-01

433

Kalman Orbit Optimized Loop Tracking  

NASA Technical Reports Server (NTRS)

Under certain conditions of low signal power and/or high noise, there is insufficient signal to noise ratio (SNR) to close tracking loops with individual signals on orbiting Global Navigation Satellite System (GNSS) receivers. In addition, the processing power available from flight computers is not great enough to implement a conventional ultra-tight coupling tracking loop. This work provides a method to track GNSS signals at very low SNR without the penalty of requiring very high processor throughput to calculate the loop parameters. The Kalman Orbit-Optimized Loop (KOOL) tracking approach constitutes a filter with a dynamic model and using the aggregate of information from all tracked GNSS signals to close the tracking loop for each signal. For applications where there is not a good dynamic model, such as very low orbits where atmospheric drag models may not be adequate to achieve the required accuracy, aiding from an IMU (inertial measurement unit) or other sensor will be added. The KOOL approach is based on research JPL has done to allow signal recovery from weak and scintillating signals observed during the use of GPS signals for limb sounding of the Earth s atmosphere. That approach uses the onboard PVT (position, velocity, time) solution to generate predictions for the range, range rate, and acceleration of the low-SNR signal. The low- SNR signal data are captured by a directed open loop. KOOL builds on the previous open loop tracking by including feedback and observable generation from the weak-signal channels so that the MSR receiver will continue to track and provide PVT, range, and Doppler data, even when all channels have low SNR.

Young, Lawrence E.; Meehan, Thomas K.

2011-01-01

434

Persistence Barcodes for Shapes  

Microsoft Academic Search

Abstract In this paper, we initiate a study of shape description and classification via theapplication of persistent homology to two tangential constructions on geometric objects. Our techniques co mbine,the differentiating power,of geometry with the classifying power of topology. The homology of our firstconstruction, the tangent complex, can distinguish between topologically identical shapes with different “sharp ” features, such as corners.

Gunnar Carlsson; Afra Zomorodian; Anne D. Collins; Leonidas J. Guibas

2005-01-01

435

Persistence barcodes for shapes  

Microsoft Academic Search

In this paper, we initiate a study of shape description and classification via the application of persistent homology to two tangential constructions on geometric objects. Our techniques combine the differentiating power of geometry with the classifying power of topology. The homology of our first construction, the tangent complex, can distinguish between topologically identical shapes with different \\

Gunnar Carlsson; Afra Zomorodian; Anne D. Collins; Leonidas J. Guibas

2004-01-01

436

Numbers as Shapes  

NSDL National Science Digital Library

In this activity students are asked to relate the numbers 1- 20 to rectangular shapes. Learners use unit squares or cubes to sort numbers by their 'shapes,' either squares, rectangles or sticks (rectangles of unit width). Ideas for implementation, extension and support are included.

437

Shape Memory Alloys  

Microsoft Academic Search

This special issue on shape memory alloys (SMA) is an encore to a special issue on the same topic edited by us six years ago (Smart Mater. Struct.9 (5) October 2000). A total of 19 papers is offered in this issue, organized into the three broad categories of modeling, characterization and applications. In addition to thermally activated shape memory alloys,

Abhijit Bhattacharyya; Dimitris C Lagoudas

2007-01-01

438

Rotating String Shapes  

NSDL National Science Digital Library

In this group activity, learners make multi-sided polygons with string. Learners slide a long piece of string through their fingers to make different kinds of triangles (isosceles, right, equilateral, and scalene) and quadrilaterals, including concave and convex shapes. Learners also draw the shapes from different points of view to explore congruency.

Exploratorium

2010-01-01

439

Pan Balance-Shapes  

NSDL National Science Digital Library

This Java applet allows children to explore a balancing tool and thus build their algebraic thinking about equivalency. By placing shapes on each side of the balance and finding equivalent sets of weights, students discover the weight of each shape in one of six built-in sets or a random set.

2011-01-01

440

How College Shapes Lives  

E-print Network

How College Shapes Lives: Understanding the Issues Trends in Higher Education Series Sandy Baum Charles Kurose Jennifer Ma October 2013 #12;Part 1: Individual and Societal Benefits2 HOW COLLEGE SHAPES LIVES: UNDERSTANDING THE ISSUES © 2013 The College Board. College Board, Advanced Placement Program, SAT

Rohs, Remo

441

Automated Coronal Loop Identification Using Digital Image Processing Techniques  

NASA Technical Reports Server (NTRS)

The results of a master thesis project on a study of computer algorithms for automatic identification of optical-thin, 3-dimensional solar coronal loop centers from extreme ultraviolet and X-ray 2-dimensional images will be presented. These center splines are proxies of associated magnetic field lines. The project is pattern recognition problems in which there are no unique shapes or edges and in which photon and detector noise heavily influence the images. The study explores extraction techniques using: (1) linear feature recognition of local patterns (related to the inertia-tensor concept), (2) parametric space via the Hough transform, and (3) topological adaptive contours (snakes) that constrains curvature and continuity as possible candidates for digital loop detection schemes. We have developed synthesized images for the coronal loops to test the various loop identification algorithms. Since the topology of these solar features is dominated by the magnetic field structure, a first-order magnetic field approximation using multiple dipoles provides a priori information in the identification process. Results from both synthesized and solar images will be presented.

Lee, Jong K.; Gary, G. Allen; Newman, Timothy S.

2003-01-01

442

Fine Structures and Overlying Loops of Confined Solar Flares  

E-print Network

Using the H$\\alpha$ observations from the New Vacuum Solar Telescope at Fuxian Solar Observatory, we focus on the fine structures of three confined flares and the issue why all the three flares are confined instead of eruptive. All the three confined flares take place successively at the same location and have similar morphologies, so can be termed homologous confined flares. In the simultaneous images obtained by the Solar Dynamics Observatory, many large-scale coronal loops above the confined flares are clearly observed in multi-wavelengths. At the pre-flare stage, two dipoles emerge near the negative sunspot, and the dipolar patches are connected by small loops appearing as arch-shaped H$\\alpha$ fibrils. There exists a reconnection between the small loops, and thus the H$\\alpha$ fibrils change their configuration. The reconnection also occurs between a set of emerging H$\\alpha$ fibrils and a set of pre-existing large loops, which are rooted in the negative sunspot, a nearby positive patch, and some remote ...

Yang, Shuhong; Xiang, Yongyuan

2014-01-01

443

Shaped composite liquid marbles.  

PubMed

Shaped "cubic" non-stick droplets are reported. Shaped composite droplets were manufactured via a two-stage process. In the first stage, cubic foamed-polystyrene particles were hydrophilized with cold radiofrequency plasma. Then particles were wetted with water. In the second stage, they were coated with solid, colloidal particles such as lycopodium, Teflon or carbon black. Thus, "liquid marble"-like non-stick shaped droplets were obtained. The shaped "cubic" droplets remained stable when supported by a NaCl water solution. Shaped Janus droplets coated on one side with dielectric Teflon and with semiconductor carbon black on the other side, were prepared. Janus marbles were actuated with an electric field. PMID:24407678

Bormashenko, Edward; Balter, Revital; Aharoni, Hadas; Aurbach, Doron

2014-03-01

444

Pulse shaping system  

DOEpatents

Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses.

Skeldon, Mark D. (Penfield, NY); Letzring, Samuel A. (Jemez Springs, NM)

1999-03-23

445

Pulse shaping system  

DOEpatents

Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses. 8 figs.

Skeldon, M.D.; Letzring, S.A.

1999-03-23

446

Thermodynamics in Loop Quantum Cosmology  

E-print Network

Loop quantum cosmology (LQC) is very powerful to deal with the behavior of early universe. And the effective loop quantum cosmology gives a successful description of the universe in the semiclassical region. We consider the apparent horizon of the Friedmann-Robertson-Walker universe as a thermodynamical system and investigate the thermodynamics of LQC in the semiclassical region. The effective density and effective pressure in the modified Friedmann equation from LQC not only determine the evolution of the universe in LQC scenario but are actually also found to be the thermodynamic quantities. This result comes from the energy definition in cosmology (the Misner-Sharp gravitational energy) and is consistent with thermodynamic laws. We prove that within the framework of loop quantum cosmology, the elementary equation of equilibrium thermodynamics is still valid.

Li-Fang Li; Jian-Yang Zhu

2008-12-18

447

Digital phase-lock loop  

NASA Technical Reports Server (NTRS)

An improved digital phase lock loop incorporates several distinctive features that attain better performance at high loop gain and better phase accuracy. These features include: phase feedback to a number-controlled oscillator in addition to phase rate; analytical tracking of phase (both integer and fractional cycles); an amplitude-insensitive phase extractor; a more accurate method for extracting measured phase; a method for changing loop gain during a track without loss of lock; and a method for avoiding loss of sampled data during computation delay, while maintaining excellent tracking performance. The advantages of using phase and phase-rate feedback are demonstrated by comparing performance with that of rate-only feedback. Extraction of phase by the method of modeling provides accurate phase measurements even when the number-controlled oscillator phase is discontinuously updated.

Thomas, Jr., Jess B. (Inventor)

1991-01-01

448

Development of Non-Optimum Factors for Launch Vehicle Propellant Tank Bulkhead Weight Estimation  

NASA Technical Reports Server (NTRS)

Non-optimum factors are used during aerospace conceptual and preliminary design to account for the increased weights of as-built structures due to future manufacturing and design details. Use of higher-fidelity non-optimum factors in these early stages of vehicle design can result in more accurate predictions of a concept s actual weights and performance. To help achieve this objective, non-optimum factors are calculated for the aluminum-alloy gores that compose the ogive and ellipsoidal bulkheads of the Space Shuttle Super-Lightweight Tank propellant tanks. Minimum values for actual gore skin thicknesses and weld land dimensions are extracted from selected production drawings, and are used to predict reference gore weights. These actual skin thicknesses are also compared to skin thicknesses predicted using classical structural mechanics and tank proof-test pressures. Both coarse and refined weights models are developed for the gores. The coarse model is based on the proof pressure-sized skin thicknesses, and the refined model uses the actual gore skin thicknesses and design detail dimensions. To determine the gore non-optimum factors, these reference weights are then compared to flight hardware weights reported in a mass properties database. When manufacturing tolerance weight estimates are taken into account, the gore non-optimum factors computed using the coarse weights model range from 1.28 to 2.76, with an average non-optimum factor of 1.90. Application of the refined weights model yields non-optimum factors between 1.00 and 1.50, with an average non-optimum factor of 1.14. To demonstrate their use, these calculated non-optimum factors are used to predict heavier, more realistic gore weights for a proposed heavy-lift launch vehicle s propellant tank bulkheads. These results indicate that relatively simple models can be developed to better estimate the actual weights of large structures for future launch vehicles.

Wu, K. Chauncey; Wallace, Matthew L.; Cerro, Jeffrey A.

2012-01-01

449

Automatic loop steering for directional drilling  

SciTech Connect

A closed loop controller design for the steering of directed drilling is proposed in the paper. The paper first describes the development of a causal model of the directed drilling process that consists of two critical components. First a closed form bottom hole assembly (BHA) model is described. The BHA model makes it possible to solve the `inverse` problem on-line in real time. That is, having measured the `shape` of the compliant BHA at any instant, the real time BHA model will be used to determine both the exact location and orientation of the bit in a global reference frame and boundary conditions of the BHA at the rock/bit interface. Those boundary conditions include the instantaneous values of the net forces and moments at the rock/bit interface. Secondly, the paper describes a proposed input-output rock/bit interaction (RBI) model that can be shown to accurately determine the directional tendency of the bit on-line. The model structure is consistent with the models proposed by Ho (1987) and Rafie (1988) in the case when a constant build/drop rate is achieved. The model is shown to mimic field data which was published by Jogi et al (1988). The BHA and RBI models are then combined to yield a continuous differential model of the drilling process. It is assumed that force inputs to the BHA are obtained from continuously variable eccentric stabilizers in the BHA near the bit. A closed loop steering control algorithm is designed around the proposed drilling process model (DPM). Finally, simulations of the controlled DPM and an uncontrolled building BHA are compared to demonstrate the feasibility of the automatic steering controller.

Patten, W.N.; Kuehn, J.L.; Ziaja, M.B. [Univ. of Oklahoma, Norman, OK (United States)

1994-12-31

450

Decentralized control of sound radiation using iterative loop recovery.  

PubMed

A decentralized model-based control strategy is designed to reduce low-frequency sound radiation from periodically stiffened panels. While decentralized control systems tend to be scalable, performance can be limited due to modeling error introduced by the unmodeled interaction between neighboring control units. Since bounds on modeling error are not known in advance, it is difficult to ensure the decentralized control system will be robust without making the controller overly conservative. Therefore an iterative approach is suggested, which utilizes frequency-shaped loop recovery. The approach accounts for modeling error introduced by neighboring control loops, requires no communication between subsystems, and is relatively simple. The control strategy is evaluated numerically using a model of a stiffened aluminum panel that is representative of the sidewall of an aircraft. Simulations demonstrate that the iterative approach can achieve significant reductions in radiated sound power from the stiffened panel without destabilizing neighboring control units. PMID:20968346

Schiller, Noah H; Cabell, Randolph H; Fuller, Chris R

2010-10-01

451

Decentralized Control of Sound Radiation Using Iterative Loop Recovery  

NASA Technical Reports Server (NTRS)

A decentralized model-based control strategy is designed to reduce low-frequency sound radiation from periodically stiffened panels. While decentralized control systems tend to be scalable, performance can be limited due to modeling error introduced by the unmodeled interaction between neighboring control units. Since bounds on modeling error are not known in advance, it is difficult to ensure the decentralized control system will be robust without making the controller overly conservative. Therefore an iterative approach is suggested, which utilizes frequency-shaped loop recovery. The approach accounts for modeling error introduced by neighboring control loops, requires no communication between subsystems, and is relatively simple. The control strategy is evaluated numerically using a model of a stiffened aluminum panel that is representative of the sidewall of an aircraft. Simulations demonstrate that the iterative approach can achieve significant reductions in radiated sound power from the stiffened panel without destabilizing neighboring control units.

Schiller, Noah H.; Cabell, Randolph H.; Fuller, Chris R.

2009-01-01

452

Inferring the in vivo looping properties of DNA  

E-print Network

The free energy of looping DNA by proteins and protein complexes determines to what extent distal DNA sites can affect each other. We inferred its in vivo value through a combined computational-experimental approach for different lengths of the loop and found that, in addition to the intrinsic periodicity of the DNA double helix, the free energy has an oscillatory component with about half the helical period. Moreover, the oscillations have such an amplitude that the effects of regulatory molecules become strongly dependent on their precise DNA positioning and yet easily tunable by their cooperative interactions. These unexpected results can confer to the physical properties of DNA a more prominent role at shaping the properties of gene regulation than previously thought.

Leonor Saiz; J. Miguel Rubi; Jose M. G. Vilar

2005-12-20

453

Loop Variables in Topological Gravity  

E-print Network

We examine the relationship between covariant and canonical (Ashtekar/Rovelli/Smolin) loop variables in the context of BF type topological field theories in 2+1 and 3+1 dimensions, with respective gauge groups SO(2,1) and SO(3,1). The latter model can be considered as the simplest topological gravity theory in 3+1 dimensions. We carry out the canonical quantization of this model in both the connection and loop representations, for the two spatial topologies $T^3$ and $S^2\\times S^1$.

Y. Bi; J. Gegenberg

1993-07-22

454

The exchangeability of shape  

PubMed Central

Background Landmark based geometric morphometrics (GM) allows the quantitative comparison of organismal shapes. When applied to systematics, it is able to score shape changes which often are undetectable by traditional morphological studies and even by classical morphometric approaches. It has thus become a fast and low cost candidate to identify cryptic species. Due to inherent mathematical properties, shape variables derived from one set of coordinates cannot be compared with shape variables derived from another set. Raw coordinates which produce these shape variables could be used for data exchange, however they contain measurement error. The latter may represent a significant obstacle when the objective is to distinguish very similar species. Results We show here that a single user derived dataset produces much less classification error than a multiple one. The question then becomes how to circumvent the lack of exchangeability of shape variables while preserving a single user dataset. A solution to this question could lead to the creation of a relatively fast and inexpensive systematic tool adapted for the recognition of cryptic species. Conclusions To preserve both exchangeability of shape and a single user derived dataset, our suggestion is to create a free access bank of reference images from which one can produce raw coordinates and use them for comparison with external specimens. Thus, we propose an alternative geometric descriptive system that separates 2-D data gathering and analyzes. PMID:20964872

2010-01-01

455

Catchment soil moisture and rainfall characteristics as determinant factors for discharge\\/suspended sediment hysteretic loops in a small headwater catchment in the Spanish pyrenees  

Microsoft Academic Search

The concentration of suspended sediment and discharge generated during flood events are not normally homogenous, and the curve representing sediment concentration vs. discharge through time is often a hysteretic loop. Three types of hysteretic loops were found at Arnás, a Mediterranean headwater catchment in the Central Spanish Pyrenees: clockwise (the most frequent), counter-clockwise and eight-shaped. They are associated with different

M. Seeger; M.-P Errea; S Beguer??a; J. Arnaez; C. Marti; J. M Garc??a-Ruiz

2004-01-01

456

Experimental investigation of penetration performance of shaped charge into concrete targets  

NASA Astrophysics Data System (ADS)

In order to develop a tandem warhead that can effectively destroy concrete targets, this paper explores the penetration performance of shaped charges with different cone angles and liner materials into concrete targets by means of experiments. The penetration process and the destruction mechanism of concrete targets by shaped charges and kinetic energy projectiles are analyzed and compared. Experimental results suggest that both kinetic energetic projectile and shaped charge are capable of destroying concrete targets, but the magnitudes of damage are different. Compared with a kinetic energy projectile, a shaped charge has more significant effect of penetration into the target, and causes very large spalling area. Hence, a shaped charge is quite suitable for first-stage charge of tandem warhead. It is also found that, with the increase of shaped charge liner cone angle, the depth of penetration decreases gradually while the hole diameter becomes larger. Penetration depth with copper liner is larger than of aluminum liner but hole diameter is relatively smaller, and the shaped charge with steel liner is between the above two cases. The shaped charge with a cone angle of 100° can form a jet projectile charge (JPC). With JPC, a hole with optimum depth and diameter on concrete targets can be formed, which guarantees that the second-stage warhead smoothly penetrates into the hole and explodes at the optimum depth to achieve the desired level of destruction in concrete targets.

Wang, Cheng; Ma, Tianbao; Ning, Jianguo

2008-06-01

457

Say It with Shapes  

NSDL National Science Digital Library

In this activity, learners make patterns consisting of words and shapes. Learners get sets of triangles, squares, and rectangles. Each shape contains a word. Learners arrange the shapes into a geometric pattern that repeats or changes in a systematic way on each line. Younger learners can create simple repeating patterns; older ones can explore patterns that grow in different ways. This activity comes with word sets in three levels of difficulty. Available as a web page and a downloadable PDF. Also available in Spanish.

TERC

2012-06-26

458

Shape Up America!  

NSDL National Science Digital Library

This site, maintained by Shape Up America! and Infosector Corporation, offers visitors a great way to keep up on the latest developments in weight management and physical fitness. Surveys, public service announcements, press releases and more are available. First-time visitors can determine their Body Mass Index (BMI), a ratio between weight and height that correlates with body fat. Shape Up America! also has beneficial information for the heath professional. Shape Up America! is a non-profit corporation established by C. Everett Koop, M.D., the former US Surgeon General.

1997-01-01

459

The Shape of Floatation  

NSDL National Science Digital Library

In this activity (on page 2 of the PDF), learners will discover how the shape of an object, not just its weight, determines whether it floats or sinks. After a ball of aluminum foil sinks in a bucket of water, the ball is opened up into a flat sheet that learners will shape into a sided tray or another shape they may come up with, then placed back in the bucket. If it floats, carefully add pennies until it sinks. Relates to the linked video, DragonflyTV GPS: Sailboat Design.

Twin Cities Public Television, Inc.

2006-01-01

460

A new single-loop single-stage low power sigma-delta modulator  

Microsoft Academic Search

This paper presents a new single-loop single-stage second order sigma-delta modulator. The circuit based on switched capacitor components just uses one Op-Amp to realize second order noise shaping. The modulator demonstrated 85 dB DR in 8kHz bandwidth, dissipating 135 ?W from a 2.5 V supply.

Amin Qasem Safarian; Farzad Sahandi; S. Mojtaba Atarodi

2002-01-01

461

A MONTE CARLO SEQUENTIAL ESTIMATION OF POINT PROCESS OPTIMUM FILTERING FOR BRAIN MACHINE INTERFACES  

E-print Network

1 A MONTE CARLO SEQUENTIAL ESTIMATION OF POINT PROCESS OPTIMUM FILTERING FOR BRAIN MACHINE Monte Carlo Sequential Estimation for Point Processes.................................................29 Simulation of Monte Carlo Sequential Estimation on Neural Spike Train Decoding............32 Interpretation

Slatton, Clint

462

Distinguishing mixed quantum states: Minimum-error discrimination versus optimum unambiguous discrimination  

E-print Network

Distinguishing mixed quantum states: Minimum-error discrimination versus optimum unambiguous discrimination Ulrike Herzog1, * and János A. Bergou2 1 Institut für Physik, Humboldt-Universität zu Berlin 2004) We consider two different optimized measurement strategies for the discrimination

463

Optimum Radio Channel Estimation with Periodic Spread Spectrum Signals Adjusted to Amplifier  

Microsoft Academic Search

A system for measuring a multipath channel Impulse response is proposed whlch offers a significantly larger dynamic range as conventlonal systems by using optimized spread spectrum test signals and optimum unbiased estimation in the receiver.

T. Felhauer; P. W. Baier

1992-01-01

464

Shapes and Poetry  

NSDL National Science Digital Library

In this math lesson, learners read the poem "Shapes" from "A Light in the Attic" by Shel Silverstein. Then, learners create their own illustration of the poem. In this lesson, learners explore geometric figures and positional words.

2012-06-26

465

Electrostatically shaped membranes  

NASA Technical Reports Server (NTRS)

Disclosed is a method and apparatus for electrostatically shaping a membrane suitable for use in antennas or the like, comprising an electrically conductive thin membrane where the periphery of said membrane is free to move in at least one direction, a first charge on the electrically conductive thin membrane to electrostatically stiffen the membrane, a second charge which shapes the electrostatically stiffened thin membrane and a restraint for limiting the movement of at least one point of the thin membrane relative to the second charge. Also disclosed is a method and apparatus for adaptively controlling the shape of the thin membrane by sensing the shape of the membrane and selectively controlling the first and second charge to achieve a desired performance characteristic of the membrane.

Silverberg, Larry M. (Inventor)

1994-01-01

466

Shape-Time Photography  

E-print Network

We introduce a new method to describe, in a single image, changes in shape over time. We acquire both range and image information with a stationary stereo camera. From the pictures taken, we display a composite image ...

Freeman, William T.

2002-01-10

467

Interactives: 3D Shapes  

NSDL National Science Digital Library

How much liquid can that glass hold? What are the dimensions of that package that's heading off to a friend overseas? Answers to both of those questions (and many more) can be found in this lovely interactive feature on 3D shapes created by experts at the Annenberg Media group. Visitors to this site will learn about three-dimensional geometric shapes by examining a number of objects through a number of interactive exercises and games. The materials are divided into four sections, which include "3D Shapes", "Surface Area & Volume", and "Platonic Solids". The "Platonic Solids" area is quite a bit of fun, as visitors will get the opportunity to print out foldable shapes such as a tetrahedron. A short fifteen question quiz that tests the materials covered by these various activities rounds out the site.

468

Shaping environmental “justices”   

E-print Network

This thesis investigates the concept of environmental justice (EJ) by tracing its origins, the process of its shaping and reshaping, and its adoption in Taiwan. EJ addresses the phenomenon of disproportionate distribution ...

Huang, Chih-Tung

2010-01-01

469

Laser shaping of cartilage  

NASA Astrophysics Data System (ADS)

The carbon dioxide laser has been used for the first time to change the cartilage's shape. After the laser irradiation the cartilage has the tendency to retain its new form. Different types of laser modified cartilage structures were studied. The inferred physical mechanism for cartilage shaping using the stresses relaxation process is presented. The clinical significance of the results for corrective laser surgery is discussed.

Sobol, Emil N.; Bagratashvili, Victor N.; Omelchenko, Alexander I.; Sviridov, Alexander P.; Helidonis, Emmanuel S.; Kavvalos, George; Christodoulou, P. N.; Naoumidi, I.; Velegrakis, G.; Ovchinnikov, Yuriy M.; Shechter, A.

1994-09-01

470

Optimum torque determination and selection of rotary shouldered drill collar connections  

E-print Network

OPTIMUM TORQUE DETERMINATION AND SELECTION OF ROTARY SHOULDERED DRILL COLLAR CONNECTIONS A Thesis by ROY STONE MARLOW III Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree... of MASTER OF SCIENCE December 1972 Major Subject: Mechanical Engineering OPTIMUM TORQUE DETERMINATION AND SELECTION OF ROTARY SHOULDERED DRILL COLLAR CONNECTIONS A Thesis by ROY STONE IfARLOW III Approved as to style and content by: (Chairman...

Marlow, Roy Stone

1972-01-01

471

Optimum Projection Angle for Attaining Maximum Distance in a Rugby Place Kick  

PubMed Central

This study investigated the effect of projection angle on the distance attained in a rugby place kick. A male rugby player performed 49 maximum-effort kicks using projection angles of between 20 and 50°. The kicks were recorded by a video camera at 50 Hz and a 2 D biomechanical analysis was conducted to obtain measures of the projection velocity and projection angle of the ball. The player’s optimum projection angle was calculated by substituting a mathematical expression for the relationship between projection velocity and projection angle into the equations for the aerodynamic flight of a rugby ball. We found that the player’s calculated optimum projection angle (30.6°, 95% confidence limits ± 1.9°) was in close agreement with his preferred projection angle (mean value 30.8°, 95% confidence limits ± 2.1°). The player’s calculated optimum projection angle was also similar to projection angles previously reported for skilled rugby players. The optimum projection angle in a rugby place kick is considerably less than 45° because the projection velocity that a player can produce decreases substantially as projection angle is increased. Aerodynamic forces and the requirement to clear the crossbar have little effect on the optimum projection angle. Key Points The optimum projection angle in a rugby place kick is about 30°. The optimum projection angle is considerably less than 45° because the projection velocity that a player can produce decreases substantially as projection angle is increased. Aerodynamic forces and the requirement to clear the crossbar have little effect on the optimum projection angle. PMID:24570626

Linthorne, Nicholas P.; Stokes, Thomas G.

2014-01-01

472

Optimum Aeroelastic Design of Resonance Type Flapping Wing for Micro Air Vehicles  

NASA Astrophysics Data System (ADS)

The optimum aeroelastic design method for a resonance-type flapping wing for a Micro Air Vehicle (MAV) is presented. It uses Complex Method and 3D Navier-Stokes code to determine the optimum structural and aerodynamic parameters of a 2 DOF flapping wing system. The method is used to design a dragonfly-type MAV, and numerical simulation shows that the designed flapping wings can generate sufficient lift to sustain the weight and sufficient thrust to overcome the body drag.

Isogai, Koji; Kamisawa, Yuichi; Sato, Hiroyuki

473

Application of a dynamic linear programming model for optimum use of range resources over time  

E-print Network

~ . ~ ~ ~ ~ ? ~ ~ ~ ~ ~ ~ ~ ~ Scope and Importance of Range Resource Use . . . . . . . . e. . . ? " . . Present Status of the Problem, Objectives of the Study 1 2 4 6 11 II. DESCRIPTION OF THE STUDY AREA, Size and Location of the Area, Major Soils and Types of Enterprises...-use concept is not unique to the area of range re- sources Agricultural economists and farmers have long been concerned with the problem of determining the optimum crop combination from an array of possible alternatives. The principles of optimum enterprise...

Sharp, Wayne Winston

1964-01-01

474

Simulations of Gyrosynchrotron Microwave Emission from an Oscillating 3D Magnetic Loop  

E-print Network

Radio observations of solar flares often reveal various periodic or quasi-periodic oscillations. Most likely, these oscillations are caused by magnetohydrodynamic (MHD) oscillations of flaring loops which modulate the emission. Interpretation of the observations requires comparing them with simulations. We simulate the gyrosynchrotron radio emission from a semi-circular (toroidal-shaped) magnetic loop containing sausage-mode MHD oscillations. The aim is to detect the observable signatures specific to the considered MHD mode and to study their dependence on the various source parameters. The MHD waves are simulated using a linear three-dimensional model of a magnetized plasma cylinder; both standing and propagating waves are considered. The curved loop is formed by replicating the MHD solutions along the plasma cylinder and bending the cylinder; this model allows us to study the effect of varying the viewing angle along the loop. The radio emission is simulated using a three-dimensional model and its spatial a...

Kuznetsov, Alexey; Reznikova, Veronika

2015-01-01

475

Universality of fragment shapes  

PubMed Central

The shape of fragments generated by the breakup of solids is central to a wide variety of problems ranging from the geomorphic evolution of boulders to the accumulation of space debris orbiting Earth. Although the statistics of the mass of fragments has been found to show a universal scaling behavior, the comprehensive characterization of fragment shapes still remained a fundamental challenge. We performed a thorough experimental study of the problem fragmenting various types of materials by slowly proceeding weathering and by rapid breakup due to explosion and hammering. We demonstrate that the shape of fragments obeys an astonishing universality having the same generic evolution with the fragment size irrespective of materials details and loading conditions. There exists a cutoff size below which fragments have an isotropic shape, however, as the size increases an exponential convergence is obtained to a unique elongated form. We show that a discrete stochastic model of fragmentation reproduces both the size and shape of fragments tuning only a single parameter which strengthens the general validity of the scaling laws. The dependence of the probability of the crack plan orientation on the linear extension of fragments proved to be essential for the shape selection mechanism. PMID:25772300

Domokos, Gábor; Kun, Ferenc; Sipos, András Árpád; Szabó, Tímea

2015-01-01

476

On Characterizing Particle Shape  

NASA Technical Reports Server (NTRS)

It is well known that particle shape affects flow characteristics of granular materials, as well as a variety of other solids processing issues such as compaction, rheology, filtration and other two-phase flow problems. The impact of shape crosses many diverse and commercially important applications, including pharmaceuticals, civil engineering, metallurgy, health, and food processing. Two applications studied here include the dry solids flow of lunar simulants (e.g. JSC-1, NU-LHT-2M, OB-1), and the flow properties of wet concrete, including final compressive strength. A multi-dimensional generalized, engineering method to quantitatively characterize particle shapes has been developed, applicable to both single particle orientation and multi-particle assemblies. The two-dimension, three dimension inversion problem is also treated, and the application of these methods to DEM model particles will be discussed. In the case of lunar simulants, flow properties of six lunar simulants have been measured, and the impact of particle shape on flowability - as characterized by the shape method developed here -- is discussed, especially in the context of three simulants of similar size range. In the context of concrete processing, concrete construction is a major contributor to greenhouse gas production, of which the major contributor is cement binding loading. Any optimization in concrete rheology and packing that can reduce cement loading and improve strength loading can also reduce currently required construction safety factors. The characterization approach here is also demonstrated for the impact of rock aggregate shape on concrete slump rheology and dry compressive strength.

Ennis, Bryan J.; Rickman, Douglas; Rollins, A. Brent; Ennis, Brandon

2014-01-01

477

Universality of fragment shapes  

NASA Astrophysics Data System (ADS)

The shape of fragments generated by the breakup of solids is central to a wide variety of problems ranging from the geomorphic evolution of boulders to the accumulation of space debris orbiting Earth. Although the statistics of the mass of fragments has been found to show a universal scaling behavior, the comprehensive characterization of fragment shapes still remained a fundamental challenge. We performed a thorough experimental study of the problem fragmenting various types of materials by slowly proceeding weathering and by rapid breakup due to explosion and hammering. We demonstrate that the shape of fragments obeys an astonishing universality having the same generic evolution with the fragment size irrespective of materials details and loading conditions. There exists a cutoff size below which fragments have an isotropic shape, however, as the size increases an exponential convergence is obtained to a unique elongated form. We show that a discrete stochastic model of fragmentation reproduces both the size and shape of fragments tuning only a single parameter which strengthens the general validity of the scaling laws. The dependence of the probability of the crack plan orientation on the linear extension of fragments proved to be essential for the shape selection mechanism.

Domokos, Gábor; Kun, Ferenc; Sipos, András Árpád; Szabó, Tímea

2015-03-01

478

Universality of fragment shapes.  

PubMed

The shape of fragments generated by the breakup of solids is central to a wide variety of problems ranging from the geomorphic evolution of boulders to the accumulation of space debris orbiting Earth. Although the statistics of the mass of fragments has been found to show a universal scaling behavior, the comprehensive characterization of fragment shapes still remained a fundamental challenge. We performed a thorough experimental study of the problem fragmenting various types of materials by slowly proceeding weathering and by rapid breakup due to explosion and hammering. We demonstrate that the shape of fragments obeys an astonishing universality having the same generic evolution with the fragment size irrespective of materials details and loading conditions. There exists a cutoff size below which fragments have an isotropic shape, however, as the size increases an exponential convergence is obtained to a unique elongated form. We show that a discrete stochastic model of fragmentation reproduces both the size and shape of fragments tuning only a single parameter which strengthens the general validity of the scaling laws. The dependence of the probability of the crack plan orientation on the linear extension of fragments proved to be essential for the shape selection mechanism. PMID:25772300

Domokos, Gábor; Kun, Ferenc; Sipos, András Árpád; Szabó, Tímea

2015-01-01

479

Recovery of solitons with nonlinear amplifying loop mirrors  

NASA Astrophysics Data System (ADS)

We study the use of nonlinear amplifying loop mirrors to recover soliton pulses nonadiabatically deformed by losses. We approach this problem as a mapping problem of input pulse to output pulse, for segments of fiber followed by a combination of linear and nonlinear amplification. For a wide range of amplifier spacings, we find numerically that a single optimal input pulse of soliton shape exists for each amplifier spacing, which is well recovered at output. The recovered output pulses contain only \\similar 3% continuous radiation.

Gabitov, Ildar; Holm, Darryl D.; Luce, Benjamin P.; Mattheus, Arnold

1995-12-01

480

Hardware-Based Non-Optimum Factors for Launch Vehicle Structural Design  

NASA Technical Reports Server (NTRS)

During aerospace vehicle conceptual and preliminary design, empirical non-optimum factors are typically applied to predicted structural component weights to account for undefined manufacturing and design details. Non-optimum factors are developed here for 32 aluminum-lithium 2195 orthogrid panels comprising the liquid hydrogen tank barrel of the Space Shuttle External Tank using measured panel weights and manufacturing drawings. Minimum values for skin thickness, axial and circumferential blade stiffener thickness and spacing, and overall panel thickness are used to estimate individual panel weights. Panel non-optimum factors computed using a coarse weights model range from 1.21 to 1.77, and a refined weights model (including weld lands and skin and stiffener transition details) yields non-optimum factors of between 1.02 and 1.54. Acreage panels have an average 1.24 non-optimum factor using the coarse model, and 1.03 with the refined version. The observed consistency of these acreage non-optimum factors suggests that relatively simple models can be used to accurately predict large structural component weights for future launch vehicles.

Wu, K. Chauncey; Cerro, Jeffrey A.

2010-01-01

481

Optimum selection of mechanism type for heavy manipulators based on particle swarm optimization method  

NASA Astrophysics Data System (ADS)

The mechanism type plays a decisive role in the mechanical performance of robotic manipulators. Feasible mechanism types can be obtained by applying appropriate type synthesis theory, but there is still a lack of effective and efficient methods for the optimum selection among different types of mechanism candidates. This paper presents a new strategy for the purpose of optimum mechanism type selection based on the modified particle swarm optimization method. The concept of sub-swarm is introduced to represent the different mechanisms generated by the type synthesis, and a competitive mechanism is employed between the sub-swarms to reassign their population size according to the relative performances of the mechanism candidates to implement the optimization. Combining with a modular modeling approach for fast calculation of the performance index of the potential candidates, the proposed method is applied to determine the optimum mechanism type among the potential candidates for the desired manipulator. The effectiveness and efficiency of the proposed method is demonstrated through a case study on the optimum selection of mechanism type of a heavy manipulator where six feasible candidates are considered with force capability as the specific performance index. The optimization result shows that the fitness of the optimum mechanism type for the considered heavy manipulator can be up to 0.578 5. This research provides the instruction in optimum selection of mechanism types for robotic manipulators.

Zhao, Yong; Chen, Genliang; Wang, Hao; Lin, Zhongqin

2013-07-01

482

Two-loop electroweak corrections to Deltar  

Microsoft Academic Search

The two-loop electroweak bosonic correction to the muon lifetime is computed using methods of asymptotic expansion. Combined with previous calculations this completes the full two-loop correction to Deltar in the Standard Model.

A. Onishchenko; O. Veretin

2003-01-01

483

Detecting and escaping infinite loops using Bolt  

E-print Network

In this thesis we present Bolt, a novel system for escaping infinite loops. If a user suspects that an executing program is stuck in an infinite loop, the user can use the Bolt user interface, which attaches to the running ...

Kling, Michael (Michael W.)

2012-01-01

484

Fragmentation of cosmic-string loops  

NASA Technical Reports Server (NTRS)

The fragmentation of cosmic string loops is discussed, and the results of a simulation of this process are presented. The simulation can evolve any of a large class of loops essentially exactly, including allowing fragments that collide to join together. Such reconnection enhances the production of small fragments, but not drastically. With or without reconnections, the fragmentation process produces a collection of nonself-intersecting loops whose typical length is on the order of the persistence length of the initial loop.

York, Thomas

1989-01-01

485

Circular loop antenna for pattern steerable applications  

Microsoft Academic Search

A circular loop antenna with feed points on the loop is proposed. This antenna is envisaged to be useful for some beam steering applications. An example of this antenna with 8 feed points is analyzed. The eight feed points are placed symmetrically on the loop, which when excited one at a time steer the beam in eight different directions at

P. Deo; A. Mehta; D. Mirshekar-SyahkaI; P. J. Massey; H. Nakano

2009-01-01

486

The eccentrically insulated circular loop antenna  

Microsoft Academic Search

The analysis for the circular loop antenna in a concentric insulating sphere is extended to the case where the loop is eccentrically located in the sphere, that is to say, coaxial with the sphere but not concentric. Both the transmitting and receiving antennas are treated. Parametric studies are used to determine the effect of the electrical size of the loop

L. N. An; Glenn S. Smith

1980-01-01

487

The eccentrically insulated circular loop antenna  

Microsoft Academic Search

In the present paper, the analysis for the circular loop antenna in a concentric insulating sphere is extended to the case where the loop is coaxial but not concentric with the sphere. The discussion covers both transmitting and receiving antennas. Parametric studies are used to determine the effect of the electrical size of the loop and sphere, the eccentricity, and

L. N. An; G. S. Smith

1980-01-01

488

The shunt-driven circular loop antenna  

Microsoft Academic Search

The distribution of current, admittance, and far field of a shunt-driven circular loop antenna are derived and related to those of an equivalent series-driven loop in parallel with a section of transmission line. The effective length of a shunt-loaded receiving antenna is obtained in terms of the corresponding quantity for the series-loaded loop.

R. King

1971-01-01

489