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1

Color Error Diffusion with GeneralizedColor Error Diffusion with Generalized Optimum Noise ShapingOptimum Noise Shaping  

E-print Network

linear distortion filtering before error diffusion · Optimize error filter h(m) for noise shaping Subject1 Color Error Diffusion with GeneralizedColor Error Diffusion with Generalized Optimum Noise;2 Optimum color noise shapingOptimum color noise shaping · Vector color error diffusion halftone model ­ We

Evans, Brian L.

2

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

3

Optimum Pulse Shape Design for UWB Systems with Timing Jitter  

NASA Astrophysics Data System (ADS)

This paper proposes a novel technique in designing the optimum pulse shape for ultra wideband (UWB) systems under the presence of timing jitter. In the UWB systems, pulse transmission power and timing jitter tolerance are crucial keys to communications success. While there is a strong desire to maximize both of them, one must be traded off against the other. In the literature, much effort has been devoted to separately optimize each of them without considering the drawback to the other. In this paper, both factors are jointly considered. The proposed pulse attains the adequate power to survive the noise floor and at the same time provides good resistance to the timing jitter. The proposed pulse also meets the power spectral mask restriction as prescribed by the Federal Communications Commission (FCC) for indoor UWB systems. Simulation results confirm the advantages of the proposed pulse over other previously known UWB pulses. Parameters of the proposed optimization algorithm are also investigated in this paper.

Lee, Wilaiporn; Kunaruttanapruk, Suwich; Jitapunkul, Somchai

4

The digital phase-locked loop as a near-optimum FM demodulator.  

NASA Technical Reports Server (NTRS)

This paper presents an approach to the optimum digital demodulation of a continuous-time FM signal using stochastic estimation theory. The primary result is a digital phase-locked loop realization possessing performance characteristics that approach those of the analog counterpart. Some practical considerations are presented and simulation results for a first-order message model are presented.

Kelly, C. N.; Gupta, S. C.

1972-01-01

5

Feedback Loops Shape Cellular Signals in Space and Time  

NSDL National Science Digital Library

This article discusses the study of feedback loops in biological systems. Positive and negative feedback loops are common regulatory elements in biological signaling systems. We discuss core feedback motifs that have distinct roles in shaping signaling responses in space and time. We also discuss approaches to experimentally investigate feedback loops in signaling systems.

Onn Brandman (University of California-San Francisco and Howard Hughes Medical Institute;Department of Cellular and Molecular Pharmacology); Tobias Meyer (Stanford University Medical Center;Department of Chemical and Systems Biology)

2008-10-17

6

Size influence on shape of handwritten characters loops.  

PubMed

In the practice of forensic handwriting experts, the size of the writing on a questioned document may be different from that of known samples. In this study, the hypothesis of shape invariance of handwritten closed loops across size increasing was tested. A Fourier methodology was applied to 2325 small letters (591 a loops, 547 d loops, 596 o loops and 591 q loops) and 692 enlarged letters (162 a loops, 173 d loops, 173 o loops and 184 q loops), in a population of 13 writers who were asked to write letters in their usual size and about three times larger. Most of the writers presented similar modifications when increasing the size of the loops; they produced enlarged loops significantly more round and less slanted towards the right or the left. Furthermore, a discrimination was demonstrated between the writers on the basis of the enlarged loops, with a correct classification rate superior to 90%, whatever the letter (a, d, o or q). A classification of the enlarged loops in their corresponding writer was then possible. On the contrary, when comparing the enlarged loops to the small ones, almost one half of the enlarged loops were allocated to a wrong writer. Shape invariance was thus not supported for this particular application. Consequently, when comparing documents with a different writing size, differences in loops shape should be interpreted cautiously because they may be due to a different writer, but they may also be due to an enlargement of the loops. Therefore, reference material of similar writing size to that of the questioned writing should be requested for the comparison of handwritten loops. PMID:17207594

Marquis, R; Taroni, F; Bozza, S; Schmittbuhl, M

2007-10-01

7

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

8

Spectrum shape compression and pedestal elimination employing a Sagnac loop  

NASA Astrophysics Data System (ADS)

We report on the experimental demonstration of a spectrum shaping filter, which is formed by inserting a fiber polarization controller (PC) in to a Sagnac loop. Pedestal free and narrow spectrum with line width at 1.4-1.7 nm is obtained, which is advantageous for further power amplification and effective frequency doubling.

Jintao, Tao; Hongjun, Liu; Cunxiao, Gao; Wei, Zhao; Yishan, Wang; Guofu, Chen

2009-01-01

9

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

10

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

11

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

12

Loop shaping design for tracking performance in machine axes.  

PubMed

A modern interpretation of classical loop shaping control design methods is presented in the context of tracking control for linear motor stages. Target applications include noncontacting machines such as laser cutters and markers, water jet cutters, and adhesive applicators. The methods are directly applicable to the common PID controller and are pertinent to many electromechanical servo actuators other than linear motors. In addition to explicit design techniques a PID tuning algorithm stressing the importance of tracking is described. While the theory behind these techniques is not new, the analysis of their application to modern systems is unique in the research literature. The techniques and results should be important to control practitioners optimizing PID controller designs for tracking and in comparing results from classical designs to modern techniques. The methods stress high-gain controller design and interpret what this means for PID. Nothing in the methods presented precludes the addition of feedforward control methods for added improvements in tracking. Laboratory results from a linear motor stage demonstrate that with large open-loop gain very good tracking performance can be achieved. The resultant tracking errors compare very favorably to results from similar motions on similar systems that utilize much more complicated controllers. PMID:16480110

Schinstock, Dale E; Wei, Zhouhong; Yang, Tao

2006-01-01

13

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

14

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

15

Nonsmooth Structured Control Design with Application to PID Loop-Shaping of a Process  

E-print Network

Nonsmooth Structured Control Design with Application to PID Loop-Shaping of a Process Pierre for descent and optimality. In the experimental part we apply our technique to H loop-shaping PID controllers for MIMO systems and demonstrate its use for PID control of a chemical process. Keywords: Nonsmooth

Noll, Dominikus

16

AUTOMATIC LOOP SHAPING IN QFT BY USING A COMPLEX FRACTIONAL ORDER  

E-print Network

AUTOMATIC LOOP SHAPING IN QFT BY USING A COMPLEX FRACTIONAL ORDER TERMS CONTROLLER Joaqu´in Cervera by using a minimum set of parameters. A fractional controller, based on complex fractional order poles of a fractional compensator, which give singular properties to automatically shape the open loop gain function

López, Joaquín Cervera

17

Optimum nanoparticles for electrocatalytic oxygen reduction: the size, shape and new design.  

PubMed

The electrocatalytic oxygen reduction reaction (ORR) on nanoparticles has attracted much attention in recent years for its significance in fuel cell applications. Here by combining density functional theory (DFT) calculations with the periodic continuum solvation model based on modified-Poisson-Boltzmann (CM-MPB) electrostatics, we analyzed the ORR activity on a set of differently sized Pt nanoparticles in order to identify the optimum particles for a better designed catalyst. We show that Pt nanoparticles of ?2 nm size have the highest ORR mass activity, which is attributed to the variation of the effective reaction sites on the exposed {111} facet at the electrochemical conditions. We propose a type of a new nanocatalyst for the electrocatalytic oxygen reduction based on the knowledge from large-scale first principles simulations on Pt nanoparticles. The new catalyst has inert metal Au as the frame for the Pt nanoparticle and exposed Pt{111} sites are the active site for oxygen reduction. Such an architecture can not only prevent the initial O corrosion at the edge sites but also significantly improve the activity. The theoretical work provides a promising new direction for the rational design of a stable and active ORR catalyst via nano-structure engineering. PMID:24077215

Wei, Guang-Feng; Liu, Zhi-Pan

2013-11-14

18

Possible Cross-Section for a Coronal Loop of Given Shape?  

NASA Astrophysics Data System (ADS)

We aim to answer the question about the cross-section of a planar coronal loop with a prescribed shape. We restrict the analysis to coronal loops embedded in a planar potential magnetic field. Then we carry out the analysis in the leading-order approximation with respect to the small parameter ? equal to the ratio of the characteristic size of the loop cross-section to the loop length. We show that, in this approximation, the loop cross-section can be prescribed arbitrarily at one of its footpoints. Then the loop cross-section at any other point is obtained by stretching or compressing the prescribed loop cross-section in the direction that is perpendicular to the loop axis and in the plane of the loop. The variation of the coefficient of stretching or compression along the loop can be chosen arbitrarily. In particular, it follows from this result that we can consider a planar loop of arbitrary shape and assume that its cross-section is circular everywhere and has a constant radius.

Ruderman, M. S.

2015-02-01

19

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

20

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

21

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. However, in many situations, it may not be possible to site a wind farm at the location with the most desirable frequency response. Here, we show that one can design a wind farm controller to shape

Gayme, Dennice

22

Multivariable robust controller design of ACLS using loop-shaping approach  

NASA Astrophysics Data System (ADS)

In this paper a multivariable robust controller design approach of the ACLS is accomplished by using robust loop-shaping techniques. In order to avoid the inefficient way of choosing the weight functions by trial-and-error method, the structured genetic algorithm (SGA) approach is introduced, which is capable of simultaneously searching the orders and coefficients of the pre- and post-compensator for weight matrices. According to this approach, engineers can achieve an ideal loop-shape which lies in an appropriate region relating to the desired performance specifications. The effectiveness of this approach is illustrated by the longitudinal equations of a carrier-based aircraft's motion design example.

Dong, Chaoyang; Cui, Haihua; Wang, Qing

2008-10-01

23

H Loop shaping control for PLL-based mechanical resonance tracking in NEMS resonant mass sensors  

E-print Network

H Loop shaping control for PLL-based mechanical resonance tracking in NEMS resonant mass sensors--A simple dynamic detection of the resonance frequency shift in NEMS resonant mass sensors is described the resonant oscillations. The sensor is driven directly by the VCO's output for which the control signal

Boyer, Edmond

24

Understanding missile autopilot design using the H? loop shaping design procedure  

Microsoft Academic Search

This paper presents different controller topologies for a missile autopilot. The controllers are based on a loop shaping design procedure due to McFarlane and Glover. The nature of the controllers obtained is discussed and a novel procedure for the selection of weights is given

Thomas J. Urban; Pete Iwaskiw; Pablo A. Iglesias

1999-01-01

25

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-Pldel, Catherine; Loral, Olivier; Tariel, Hugues; Lucas, Jacques; Bureau, Bruno

2014-01-01

26

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-Pldel, Catherine; Loral, Olivier; Tariel, Hugues; Lucas, Jacques; Bureau, Bruno

2014-01-01

27

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

28

A study of optimum cowl shapes and flow port locations for minimum drag with effective engine cooling, volume 1  

NASA Technical Reports Server (NTRS)

The contributions to the cruise drag of light aircraft arising from the shape of the engine cowl and the forward fuselage area and also that resulting from the cooling air mass flow through intake and exhaust sites on the nacelle were analyzed. The methods employed for the calculation of the potential flow about an arbitrary three dimensional body are described with modifications to include the effects of boundary layer displacement thickness, a nonuniform onset flow field (such as that due to a rotating propeller), and the presence of air intakes and exhausts. A simple, reliable, largely automated scheme to better define or change the shape of a body is also presented. A technique was developed which can yield physically acceptable skin friction and pressure drag coefficients for isolated light aircraft bodies. For test cases on a blunt nose Cessna 182 fuselage, the technique predicted drag reductions as much as 28.5% by body recontouring and proper placements and sizing of the cooling air intakes and exhausts.

Fox, S. R.; Smetana, F. O.

1980-01-01

29

Photonic multi-shape UWB pulse generation using a semiconductor optical amplifier-based nonlinear optical loop mirror  

NASA Astrophysics Data System (ADS)

We propose and demonstrate a scheme to implement photonic multi-shape ultra-wideband (UWB) signal generation using a semiconductor optical amplifier (SOA) based nonlinear optical loop mirror (NOLM). By employing the cross phase modulation (XPM) effect, cross gain modulation (XGM), or both, multi-shape UWB waveforms are generated including monocycle, doublet, triplet, and quadruplet pulses. Both the shapes and polarities of the generated pulses are flexible to adjust, which may be very useful in UWB pulse shape modulation and pulse polarity modulation.

Luo, Bo-Wen; Dong, Jian-Ji; Yu, Yuan; Yang, Ting; Zhang, Xin-Liang

2013-02-01

30

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

31

Study of the three-dimensional shape and dynamics of coronal loops observed by Hinode/EIS  

E-print Network

We study plasma flows along selected coronal loops in NOAA Active Region 10926, observed on 3 December 2006 with Hinode's EUV Imaging Spectrograph (EIS). From the shape of the loops traced on intensity images and the Doppler shifts measured along their length we compute their three-dimensional (3D) shape and plasma flow velocity using a simple geometrical model. This calculation was performed for loops visible in the Fe VIII 185 Ang., Fe X 184 Ang., Fe XII 195 Ang., Fe XIII 202 Ang., and Fe XV 284 Ang. spectral lines. In most cases the flow is unidirectional from one footpoint to the other but there are also cases of draining motions from the top of the loops to their footpoints. Our results indicate that the same loop may show different flow patterns when observed in different spectral lines, suggesting a dynamically complex rather than a monolithic structure. We have also carried out magnetic extrapolations in the linear force-free field approximation using SOHO/MDI magnetograms, aiming toward a first-order...

Syntelis, P; Georgoulis, M K; Alissandrakis, C E; Tsinganos, K

2012-01-01

32

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

33

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

34

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

35

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

Microsoft Academic Search

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

Prabir Barooah; Nancy Rey

2002-01-01

36

Precise open-loop control of MEMS deformable mirror shape Thomas Bifano a,c  

E-print Network

error. Keywords: MEMS, adaptive optics, open-loop control, deformable mirror 1. INTRODUCTION In some that counteracts the effects of aberrations. In its simplest form, such an adaptive optics controller consists of a wavefront sensor, a deformable mirror (DM), and a real-time control system that links the two, imposing

37

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

38

Loop shaped dicarboxylate-bridged dimolybdenum(II) bisphosphine compounds--a rational synthesis.  

PubMed

The reaction of the tetrametallic molecular loop [(CH3CN)6Mo2(OOC-C4H6-COO)]2[BF4]4 (1) (1 equiv.) with 2 equiv. of bis(diphenylphosphino)amine (dppa), 1,2-bis(diphenylphosphino)ethane (dppe) and bis(diphenylphosphino)methane (dppm) in propionitrile leads to the formation of the still tetrametallic complexes [(CH3CH2CN)4(X)Mo2(OOC-C4H6-COO)]2[BF4]4 (X = dppa (2), dppe (3), dppm (4)), also displaying a loop structure. All three complexes are characterized by NMR spectroscopy ((1)H, (11)B, (13)C{(1)H}, (19)F, (31)P{(1)H}), IR spectroscopy, elemental analysis, TG-MS measurements and UV-vis spectroscopy, compounds 2 and 3 additionally by X-ray single crystal diffraction. PMID:25187997

Hhne, Dominik; Herdtweck, Eberhardt; Pthig, Alexander; Khn, Fritz E

2014-11-01

39

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 Mnchengladbach (Germany); Blachowicz, Tomasz [Silesian University of Technology, Institute of Physics, Center for Science and Education, 44-100 Gliwice (Poland)

2014-08-15

40

Loop-closure events during protein folding: Rationalizing the shape of Phi-value distributions  

E-print Network

In the past years, the folding kinetics of many small single-domain proteins has been characterized by mutational Phi-value analysis. In this article, a simple, essentially parameter-free model is introduced which derives folding routes from native structures by minimizing the entropic loop-closure cost during folding. The model predicts characteristic folding sequences of structural elements such as helices and beta-strand pairings. Based on few simple rules, the kinetic impact of these structural elements is estimated from the routes and compared to average experimental Phi-values for the helices and strands of 15 small, well-characterized proteins. The comparison leads on average to a correlation coefficient of 0.62 for all proteins with polarized Phi-value distributions, and 0.74 if distributions with negative average Phi-values are excluded. The diffuse Phi-value distributions of the remaining proteins are reproduced correctly. The model shows that Phi-value distributions, averaged over secondary structural elements, can often be traced back to entropic loop-closure events, but also indicates energetic preferences in the case of a few proteins governed by parallel folding processes.

Thomas R. Weikl

2005-02-15

41

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

42

Quantitative characterization of stream turbidity-discharge behavior using event loop shape modeling and power law parameter decorrelation  

NASA Astrophysics Data System (ADS)

behavior in streams is a complex and dynamic function of both source material supply and event-driven transport. While the primary controls on turbidity behavior across time and space are still not fully understood, recent increases in the availability of high temporal resolution, colocated stream turbidity, and discharge data provide an opportunity for more detailed analysis. Here we examine methods to quantitatively characterize event responses by modeling the shape of turbidity-discharge hysteresis loops. A total of 1559 events from 20 gages in the Mid-Atlantic region of the U.S. were modeled using both previously reported models and new models combining elements of existing models. The results suggest that a more general power law-based model, utilizing both a discharge rate of change term and a "supply" term, allows characterization of a wide range of simple and complex events. Additionally, this study explores a decorrelation approach to address the strong correlation frequently observed between the power law model coefficient (a) and exponent (b), with the goal of exposing the underlying behavior of each parameter individually. An examination of seasonal parameter behavior suggests that this approach may facilitate greater physically based interpretation of the power law coefficient. The power law parameter decorrelation strategy and the loop models examined here provide a step toward the larger goal of understanding the physical controls on turbidity-discharge hysteretic behavior.

Mather, Amanda L.; Johnson, Richard L.

2014-10-01

43

Messenger RNA fluctuations and regulatory RNAs shape the dynamics of a negative feedback loop  

NASA Astrophysics Data System (ADS)

Single-cell experiments of simple regulatory networks can markedly differ from cell population experiments. Such differences arise from stochastic events in individual cells that are averaged out in cell populations. For instance, while individual cells may show sustained oscillations in the concentrations of some proteins, such oscillations may appear damped in the population average. In this paper we investigate the role of RNA stochastic fluctuations as a leading force to produce a sustained excitatory behavior at the single-cell level. As opposed to some previous models, we build a fully stochastic model of a negative feedback loop that explicitly takes into account the RNA stochastic dynamics. We find that messenger RNA random fluctuations can be amplified during translation and produce sustained pulses of protein expression. Motivated by the recent appreciation of the importance of noncoding regulatory RNAs in post-transcription regulation, we also consider the possibility that a regulatory RNA transcript could bind to the messenger RNA and repress translation. Our findings show that the regulatory transcript helps reducing gene expression variability both at the single-cell level and at the cell population level.

Rodrguez Martnez, Mara; Soriano, Jordi; Tlusty, Tsvi; Pilpel, Yitzhak; Furman, Itay

2010-03-01

44

[Carcinoma of the hypopharynx: reconstruction of the pharyngo-esophageal tract after circular pharyngectomy by the transplantation of a U-shaped jejunal loop to the neck].  

PubMed

Reconstruction of the oro- and hypopharynx has specific difficulties duo to their wide diameters. Thirteen patients underwent reconstruction with a free U-shaped jejunal transplant, after circular pharyngo-laryngectomy for hypopharyngeal cancer invading the oropharynx. This transplant included a side-to-side anastomosis between the two limbs of the jejunal loop and allowed reconstruction of the upper digestive tract after wide carcinologic resection of the pharynx. The U-shaped jejunal transplant facilitated the upper anastomosis, especially the upper part where the resection involved the oropharynx. It formed a reservoir behind the tongue and avoided nasal reflux. Best indication are large resections involving the oropharynx. PMID:10793764

Filippetti, M; Graziano, F; Santoro, E; Marzetti, F; Germain, M A; Julieron, N

1999-01-01

45

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. ...

Stringfield, Miss

2008-11-17

46

Robust Voltage Stabilization in an Isolated Wind-Diesel Power System using PSO based-Fixed Structure H? Loop Shaping Control  

NASA Astrophysics Data System (ADS)

It is well known that the power system controller designed by H? control is complicated, high order and impractical. In power system applications, practical structures such as proportional integral derivative (PID) etc., are widely used, because of their simple structure, less number of tuning parameters and low-order. However, tuning of controller parameters to achieve a good performance and robustness is based on designer's experiences. To overcome this problem, this paper proposes a fixed structure robust H? loop shaping control to design Static Var Compensator (SVC) and Automatic Voltage Regulator (AVR) for robust stabilization of voltage fluctuation in an isolated wind-diesel hybrid power system. The structure of the robust controller of SVC and AVR is specified by a PID controller. In the system modeling, a normalized coprime factorization is applied to represent possible unstructured uncertainties in the power system such as variation of system parameters, generating and loading conditions etc. Based on the H? loop shaping, the performance and robust stability conditions are formulated as the optimization problem. The particle swarm optimization is applied to solve for PID control parameters of SVC and AVR simultaneously. Simulation studies confirm the control effect and robustness of the proposed control.

Vachirasricirikul, Sitthidet; Ngamroo, Issarachai; Kaitwanidvilai, Somyot

47

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

48

Optimum transonic wind tunnel  

NASA Technical Reports Server (NTRS)

The optimum facility to complement existing high Reynolds number transonic wind tunnels is discussed. It is proposed that the facility be cryogenic, have a total pressure of five atmospheres or less, and have a test section on the order of 4- to 5-meters square. The large size is to accommodate complicated models such as those used in propulsion testing. It is suggested that magnetic suspension and wall interference minimization and correction procedures be used. Simplicity of initial design is stressed as a means of providing for future growth opportunities.

Barnwell, R. W.; Edwards, C. L. W.; Kilgore, R. A.; Dress, D. A.

1986-01-01

49

JOINT PERFORMANCE Guide for Optimum  

E-print Network

July 2012 JOINT PERFORMANCE Guide for Optimum of Concrete Pavements #12; #12;Guide for Optimum Joint Performance of Concrete Pavements i Technical Report Documentation Page 1. Report No. 2. Report Date Guide for Optimum Joint Performance of Concrete Pavements July 2012 6. Performing

50

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

51

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

52

Environmentally constrained optimum economic dispatch  

Microsoft Academic Search

This paper presents a general formulation of the optimum economic load dispatch problem in a system with thermal plants taking into account the constraints on emission of sulfur dioxide and oxides of nitrogen. The proposed algorithm is useful to determine the optimum mix-ratio of high sulfur content and low sulfur content fuels, to limit the sulfur dioxide (SO2) emission per

R. S. Kumar; K. C. S. Thampathy

1998-01-01

53

Loop shaping of structural dynamics  

E-print Network

behavior of a magnetorheological damper is developed using a neural network. Finally, an example of an application of the linear viscous damping device is given by means of a widely used benchmark problem. It is shown that design of dynamic characteristics...

Kim, Byeong Hwa

1999-01-01

54

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

55

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

56

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

57

Optimum placement of piezoelectric ceramic modules for vibration suppression of highly constrained structures  

NASA Astrophysics Data System (ADS)

The vibration suppression efficiency of so-called shunted piezoelectric systems is decisively influenced by the number, shape, dimensions and position of the piezoelectric ceramic elements integrated into the structure. This paper presents a procedure based on evolutionary algorithms for optimum placement of piezoelectric ceramic modules on highly constrained lightweight structures. The optimization loop includes the CAD software CATIA V5, the FE package ANSYS and DynOPS, a proprietary software tool able to connect the Evolving Object library with any simulation software that can be started in batch mode. A user-defined piezoelectric shell element is integrated into ANSYS 9.0. The generalized electromechanical coupling coefficient is used as the optimization objective. Position, dimensions, orientation, embedding location in the composite lay-up and wiring of customized patches are determined for optimum vibration suppression under consideration of operational and manufacturing constraints, such as added mass, maximum strain and requirements on the control circuit. A rear wing of a racing car is investigated as the test object for complex, highly constrained geometries.

Belloli, Alberto; Ermanni, Paolo

2007-10-01

58

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  

NASA Astrophysics Data System (ADS)

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 & 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 ?), 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.

2009-12-01

59

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

60

Optimum performance of hovering rotors  

NASA Technical Reports Server (NTRS)

A theory for the optimum performance of a rotor hovering out of ground effect is developed. The performance problem is formulated using general momentum theory for an infinitely bladed rotor, and the effect of a finite number of blades is estimated. The analysis takes advantage of the fact that a simple relation exists between the radial distributions of static pressure and angular velocity in the ultimate wake, far downstream of the rotor, since the radial velocity vanishes there. This relation permits the establishment of an optimum performance criterion in terms of the ultimate wake velocities by introducing a small local perturbation of the rotational velocity and requiring the resulting ratio of thrust and power changes to be independent of the radial location of the perturbation. This analysis fully accounts for the changes in static pressure distribution and axial velocity distribution throughout the wake as the result of the local perturbation of the rotational velocity component.

Wu, J. C.; Goorjian, P. M.

1972-01-01

61

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

62

Preliminary Studies on the Optimum Shape of Dental Bridges  

Microsoft Academic Search

Several pre-existing anterior and posterior dental bridge models using Finite elements and the new ceramic material In-Ceram have been developed. The mechanical behaviour of these models has been compared with optimised profiles obtained from a newly developed evolutionary algorithm known as Evolutionary Structural Optimisation (ESO).The results show that the mechanical behaviour of the bridges was mainly restricted by the properties

KAAREL PROOS; GRANT STEVEN; MIKE SWAIN; JIM IRONSIDE

2001-01-01

63

Optimum shapes for lightweighted mirrors. [of astronomical telescopes  

NASA Technical Reports Server (NTRS)

Two types of monolithic lightweight mirrors with arched backs, the center-supported single arch and the ring-supported double arch, are discussed. It is shown that, assuming a maximum permissible rms tolerance of 6 x 10 to the -6th in, the single arch mirror weighs about 50 percent of an equivalent solid mirror up to a diameter of 24 in. The single arch is relatively simple to construct and uses a simple center support. Where a better figure is required, or for larger sizes, the double arch is superior in performance to the single arch. The weight of the double arch will vary from about 50 to under 40 percent of an equivalent conventional mirror as the diameter is increased from 20 to 144 in. Further weight reduction for the double arch is possible through the reduction of the size of the support.

Vukobratovich, D.; Iraninejad, B.; Richard, R. M.; Hansen, Q. M.; Melugin, R.

1982-01-01

64

Optimum gradient of mountain paths.  

PubMed

By combining the experiment results of R. Margaria (Atti Accad. Naz. Lincei Memorie 7: 299-368, 1938), regarding the metabolic cost of gradient locomotion, together with recent insights on gait biomechanics, a prediction about the most economical gradient of mountain paths (approximately 25%) is obtained and interpreted. The pendulum-like mechanism of walking produces a waste of mechanical work against gravity within the gradient range of up to 15% (the overall efficiency is dominated by the low transmission efficiency), whereas for steeper values only the muscular efficiency is responsible for the (slight) metabolic change (per meter of vertical displacement) with respect to gradient. The speeds at the optimum gradient turned out to be approximately 0.65 m/s (+0.16 m/s vertical) and 1.50 m/s (-0.36 m/s vertical), for uphill and downhill walking, respectively, and the ascensional energy expenditure was 0.4 and 2.0 ml O2.kg body mass-1.vertical m-1 climbed or descended. When the metabolic power becomes a burden, as in high-altitude mountaineering, the optimum gradient should be reduced. A sample of real mountain path gradients, experimentally measured, mimics the obtained predictions. PMID:8594031

Minetti, A E

1995-11-01

65

Shapes of interacting RNA complexes.  

PubMed

Shapes of interacting RNA complexes are studied using a filtration via their topological genus. A shape of an RNA complex is obtained by (iteratively) collapsing stacks and eliminating hairpin loops. This shape projection preserves the topological core of the RNA complex, and for fixed topological genus there are only finitely many such shapes. Our main result is a new bijection that relates the shapes of RNA complexes with shapes of RNA structures. This allows for computing the shape polynomial of RNA complexes via the shape polynomial of RNA structures. We furthermore present a linear time uniform sampling algorithm for shapes of RNA complexes of fixed topological genus. PMID:25075750

Fu, Benjamin M M; Reidys, Christian M

2014-09-01

66

Neoclassical formulations of optimum population theory  

E-print Network

) August 1971 73 ABSTRACT Neoclassical Formulations of Optimum Population Theory. (August 1971) Glenn Anthony Davis, B. A, , Texas A&tl University Directed by: Dr. Alfred Chalk This thesis commences with a discussion of the origin of the optimum... of the theory of optimum population, as well as its modern formulation. ACKNOWLEDGENENTS I wish to thank Dr. Alfred Chalk for his help and editorial comments in the final preparation of this manuscript. I wish to express my sincere appreciation to Dr. I. 0...

Davis, Glenn Anthony

1971-01-01

67

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

68

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

69

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

70

Approach of Non-optimum Analysis on Information Systems Security  

Microsoft Academic Search

A kind of theory surrounding with sub-optimum information system, the systematical non-optimum analysis method, has been presented, and thereby the practice courses and results of mankind are classified by their natures into three categories: optimum, sub-optimum and non-optimum, and also, the way of seeking out the maximum sub-optimum has been found out. It is considered that the non-optimum system information

Libo Hou; Ping He

2009-01-01

71

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! ...

Popwell, Ms.

2010-09-22

72

Dynamic Aperture-based Solar Loop Segmentation  

NASA Technical Reports Server (NTRS)

A new method to automatically segment arc-like loop structures from intensity images of the Sun's corona is introduced. The method constructively segments credible loop structures by exploiting the Gaussian-like shape of loop cross-sectional intensity profiles. The experimental results show that the method reasonably segments most of the well-defined loops in coronal images. The method is only the second published automated solar loop segmentation method. Its advantage over the other published method is that it operates independently of supplemental time specific data.

Lee, Jon Kwan; Newman, Timothy S.; Gary, G. Allen

2006-01-01

73

Optimum Polarization for Foliage Camouflaged Target Discrimination  

E-print Network

Optimum Polarization for Foliage Camouflaged Target Discrimination Using a Genetic Algorithm camouflaged target detection at low microwave frequencies is investigated, using a powerful foliage and hard. Based on fully polarimetric simulation results of a foliage camouflaged metallic target a polarization

Sarabandi, Kamal

74

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

75

Classical and hyperbolic approximation of hysteresis loops  

NASA Astrophysics Data System (ADS)

Analytical approximation of symmetrical and unsymmetrical hysteresis loops is based on the general description of magnetization consisting of the slow reversible process and more violent irreversible process. The coercivity term in the irreversible component generates symmetrical hysteresis loops, which are used for the approximation of first-order reversal curves and their distribution. Model has been applied to materials with typical S-shaped and rectangular hysteresis loops.

W?odarski, Zdzis?aw

2007-02-01

76

Shape Times Shape  

NSDL National Science Digital Library

This problem helps children become familiar with the idea of a symbol (in this case a shape) representing a number. Students also have an opportunity to see the multiplication properties of one and zero in a challenging puzzle. By studying the twelve multiplication equations which use eleven different colored shapes, students are to determine each shape's unique number value from a list of 0 to 12. The Teachers' Notes page offers rationale, suggestions for implementation, discussion questions, support with down loadable handouts and a link to an extension activity, What's It Worth? (cataloged separately).

2007-08-01

77

Compressible vortex loops: Effect of nozzle geometry  

Microsoft Academic Search

Vortex loops are fundamental building blocks of supersonic free jets. Isolating them allows for an easier study and better understanding of such flows. The present study looks at the behaviour of compressible vortex loops of different shapes, generated due to the diffraction of a shock wave from a shock tube with different exit nozzle geometries. These include a 15mm diameter

H. Zare-Behtash; K. Kontis; N. Gongora-Orozco; K. Takayama

2009-01-01

78

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...

79

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

80

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

81

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

82

Optimum jet mixing in a tubular reactor  

SciTech Connect

The rapid mixing of two miscible fluids is a precursor to promoting fluid-phase reactions. The configuration of a turbulent jet in a crossflow or tee-mixer is the most efficient passive design for rapid mixing. Here the Damkohler number has been defined from available tee-mixer data where the reactions are slow to fast compared with mixing times. For the available data the Damkohler number has been found to be of secondary importance for optimum design. The numerical simulation of jets in a tubular reactor suggests that large jet-to-tube momentum ratios with no backmixing are superior. Moreover, the optimum design of maximum jet entrainment is shown to be synonymous with either a minimum in the relative standard deviation or the skewness. A formula relating the optimum diameter ratio to the jet-to-tube flow ratio has also been derived assuming geometrically similar jet trajectories, and the result correlates both numerical and experimental data.

Forney, L.J.; Nafia, N. [Georgia Inst. of Technology, Atlanta, GA (United States). School of Chemical Engineering] [Georgia Inst. of Technology, Atlanta, GA (United States). School of Chemical Engineering; Vo, H.X. [Dow Corning Corp., Midland, MI (United States)] [Dow Corning Corp., Midland, MI (United States)

1996-11-01

83

The Origin of Postflare Loops  

NASA Astrophysics Data System (ADS)

We apply a tracking technique, previously developed to study motions in the outer corona by Sheeley, Walters, Wang, and Howard, to 195 filtergrams obtained with the Transition Region and Coronal Explorer (TRACE) satellite and obtain height-time maps of the motions in the hot (10-20 MK) plasma clouds above postflare loop systems. These maps indicate the following two main characteristics. (1) Within the plasma cloud, the motions are downward at speeds of approximately 4 km s-1. The cloud itself grows with time, its upper layers being replenished by the arrival and deceleration of fast inflows and its lower layers disappearing when they cool to form the tops of new postflare loops. (2) Early in these events, the inward motions are turbulent, showing a variety of dark elongated features resembling ``tadpoles'' and some bright features. Later, the inflows are visible as dark collapsing loops, changing from initially cusp-shaped features to rounder loops as they move inward. Their speeds initially lie in the range 100-600 km s-1 but decrease to 4 km s-1 in about 3 minutes, corresponding to an average deceleration ~1500 m s-2. Combining these observations with similar observations obtained at reconnection sites in the outer corona by the Large Angle Spectrometric Coronagraph (LASCO), we conclude that postflare loops are the end result of the formation, filling, deceleration, and cooling of magnetic loops produced by the reconnection of field lines blown open in the flare. The formation of collapsing loops occurs in the dark tadpoles; the filling of these initially dark loops occurs via chromospheric evaporation, which also contributes to the deceleration of the loops; and the radiative cooling ultimately resolves the loops into sharply defined structures.

Sheeley, N. R., Jr.; Warren, H. P.; Wang, Y.-M.

2004-12-01

84

Optimum Detection of Frequency-Hopped Signals  

NASA Technical Reports Server (NTRS)

This paper derives and analyzes optimum and near-optimum structures for detecting frequency-hopped (FH) signals with arbitrary modulation in additive white Gaussian noise. The principalmodulation formats considered are M-ary frequency-shift-keying (MFSK) with fast frequency hopping(FFH) wherein a single tone is transmitted per hop, and slow frequency hopping (SFH) with multipleMFSK tones (data symbols) per hop. The SFH detection category has not previously been addressedin the open literature and its analysis is generally more complex than FFH.

Cheng, Unjeng; Levitt, Barry; Polydoros, Andreas; Simon, Marvin K.

1992-01-01

85

Comparative study of decay ratios of disturbance-rejection magnitude optimum method for PI controllers.  

PubMed

One of the key time-domain closed-loop performance requirements is the closed-loop response decay ratio. In this paper, the decay ratios of the disturbance-rejection magnitude optimum (DRMO) tuning method [Vranci? D, Strmcnik S, Kocijan J. Improving disturbance rejection of PI controllers by means of the magnitude optimum method. ISA Trans 2004; 43: 73-84; Vranci? D, Strmcnik S. Achieving optimal disturbance rejection by using the magnitude optimum method. In: Pre-prints of the CSCC'99 conference. 1999. p. 3401-6] are analyzed and compared to decay ratios of two other modern tuning methods, i.e. the Kappa-Tau tuning method (based on time-domain step-response characteristics) [Astrm KJ, Hgglund T. PID controllers: Theory, design, and tuning. 2nd ed. Instrument Society of America; 1995] and the non-convex optimization tuning method (based on frequency response) [Panagopoulos H, Astrm KJ, Hgglund T. Design of PI controllers based on non-convex optimization. Automatica 1998; 34: 585-601; Panagopoulos H, Astrm KJ, Hgglund T. Design of PID controllers based on constrained optimisation. IEE Proc Control Theory Appl 2002; 149 (1): 32-40]. It is shown that the DRMO method results in such a closed-loop response that the decay ratio is within a relatively narrow interval when compared to the other two methods. PMID:17706651

Lumbar, Satja; Vranci?, Damir; Strmcnik, Stanko

2008-01-01

86

Control of variable speed wind energy conversion system using a wind speed sensorless optimum speed MPPT control method  

Microsoft Academic Search

This paper presents a wind speed sensorless maximum power point tracking (MPPT) controller for variable speed wind energy conversion systems (WECS). The proposed controller generates at its output the optimum speed (OS) command for the speed control loop of the vector controlled machine side converter control system without requiring the knowledge of wind speed. The MPPT control of the WECS

J. S. Thongam; P. Bouchard; R. Beguenane; A. F. Okou; A. Merabet

2011-01-01

87

Hidden Loop Recovery for Handwriting Recognition David Doermann  

E-print Network

loop recovery based on contour dependent blob analysis is described. Proceedings of the Eighth] for a detailed explanation). In this case shape analysis is required. In cursive handwriting a loop is formed. Usually the principle component of the loop would be perpendicular to the writing direction. Therefore

Rivlin, Ehud

88

EFP05 -OPTIPOLYGEN Optimum integration of  

E-print Network

EFP05 - OPTIPOLYGEN Optimum integration of polygeneration in the food industry FORCE Technology Udarbejdet for Energistyrelsen under EFP Energieffektivisering J.nr. 33031-0083 #12;List of content 1 energy inputs to create multiple energy outputs. The aim of the project OPTIPOLYGEN is to investigate

89

DESIGN GUIDELINES FOR AN OPTIMUM SCRUBBER SYSTEM  

EPA Science Inventory

The report gives results of a review of the performance and operating experience of existing utility scrubber systems and the state-of-the-art in design of scrubber components. It also gives guidelines for the design of the optimum wet scrubber system, based on this review. The U...

90

Optimum conditions for microbial carbonate precipitation  

Microsoft Academic Search

The type of bacteria, bacterial cell concentration, initial urea concentration, reaction temperature, the initial Ca2+ concentration, ionic strength, and the pH of the media are some factors that control the activity of the urease enzyme, and may have a significant impact on microbial carbonate precipitation (MCP). Factorial experiments were designed based on these factors to determine the optimum conditions that

George D. O. Okwadha; Jin Li

2010-01-01

91

Optimum Fiducials under Weak Perspective Projection  

Microsoft Academic Search

We investigate how a given fixed number of points should be located in space so that the pose of a camera viewing them from unknown locations can be estimated with the greatest accuracy. We show that optimum solutions are ob- tained when the points form concentric complete regular polyhedra. For the case of optimal configurations we pro- vide a worst-case

Alfred M. Bruckstein; Robert J. Holt; Thomas S. Huang; Arun N. Netravali

1999-01-01

92

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

93

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

94

Optimum spectral bands for rock discrimination  

NASA Technical Reports Server (NTRS)

Using stepwise discriminant analysis on spectral reflectance and spectral emissivity data collected by a Multispectral Scanner and Data System, mounted in an NC-130B aircraft and flown at an altitude of approximately 3 km, spectral bands were ranked as to their usefulness in separating specific rock types and rock alteration products in seven geologically diverse Utah sites. The optimum band for rock discrimination included the 1.18 to 1.30 micron interval, and the optimum combination of bands comprised the 1.18 to 1.30, 4.50 to 4.75, 0.46 to 0.50, 1.52 to 1.73, and 2.10 to 2.36 micron intervals. It is concluded that the spectral interval combination was more successful in differentiating geologic materials than either simulated Multispectral Scanner bands or simulated Thematic Mapper bands.

Siegrist, A. W.; Schnetzler, C. C.

1980-01-01

95

Optimum frame synchronization for biorthogonally coded data  

NASA Technical Reports Server (NTRS)

Many recent American unmanned planetary probes have used biorthogonally coded spacecraft-to-earth telemetry links. An examination of the frame-synchronization (sync) techniques employed on these missions revealed that they were not specifically designed for coded data. This led to a consideration of the optimum frame-sync problem for biorthogonally coded data received over the additive white Gaussian noise (AWGN) channel and decoded prior to sync acquisition. A frame-sync algorithm for biorthogonally coded data based on a super-symbol distance rule is proposed, along with a corresponding selection criterion for the sync sequence. It is argued heuristically that this approach is optimum with regard to minimizing the probability of false synchronization.

Levitt, B. K.

1974-01-01

96

Development of an Optimum Flight Control System  

Microsoft Academic Search

This paper presents optimum Autopilot Designs for bank-to-turn CLOS (BTT) guidance. BTT is capable of producing higher lift-to-drag ratio. Linear quadratic optimal technique is used in this paper for the design of the roll and pitch autopilot. Simulation results have demonstrated the improvements in control with the linear quadratic optimal design. Increasingly severe mission requirements and the potential for improved

E. K. Teoh; D. P. Mital; K. S. Ang

1991-01-01

97

Optimum folding pathways of proteins: Their determination and properties  

NASA Astrophysics Data System (ADS)

We develop a dynamic optimization technique for determining optimum folding pathways of proteins starting from different initial configurations. A coarse-grained Go model is used. Forces acting on each bead are (i) the friction force, (ii) forces from bond length constraints, (iii) excluded volume constraints, and (iv) attractive forces between residue pairs that are in contact in the native state. An objective function is defined as the total attractive energy between nonbonded residues, which are neighbors in the native state. The objective function is minimized over all feasible paths, satisfying bond length and excluded volume constraints. The optimization problem is nonconvex and contains a large number of constraints. An augmented Lagrangian method with a penalty barrier function was used to solve the problem. The method is applied to a 36-residue protein, chicken villin headpiece. Sequences of events during folding of the protein are determined for various pathways and analyzed. The relative time scales are compared and scaled according to experimentally measured events. Formation times of the helices, turn, and the loop agree with experimental data. We obtain the overall folding time of the protein in the range of 600ns-1.2?s that is smaller than the experimental result of 4-5?s, showing that the optimal folding times that we obtain may be possible lower bounds. Time dependent variables during folding and energies associated with short- and long-range interactions between secondary structures are analyzed in modal space using Karhunen-Loeve expansion.

Gner, U?ur; Arkun, Yaman; Erman, Burak

2006-04-01

98

Optimum folding pathways of proteins: their determination and properties.  

PubMed

We develop a dynamic optimization technique for determining optimum folding pathways of proteins starting from different initial configurations. A coarse-grained Go model is used. Forces acting on each bead are (i) the friction force, (ii) forces from bond length constraints, (iii) excluded volume constraints, and (iv) attractive forces between residue pairs that are in contact in the native state. An objective function is defined as the total attractive energy between nonbonded residues, which are neighbors in the native state. The objective function is minimized over all feasible paths, satisfying bond length and excluded volume constraints. The optimization problem is nonconvex and contains a large number of constraints. An augmented Lagrangian method with a penalty barrier function was used to solve the problem. The method is applied to a 36-residue protein, chicken villin headpiece. Sequences of events during folding of the protein are determined for various pathways and analyzed. The relative time scales are compared and scaled according to experimentally measured events. Formation times of the helices, turn, and the loop agree with experimental data. We obtain the overall folding time of the protein in the range of 600 ns-1.2 micros that is smaller than the experimental result of 4-5 micros, showing that the optimal folding times that we obtain may be possible lower bounds. Time dependent variables during folding and energies associated with short- and long-range interactions between secondary structures are analyzed in modal space using Karhunen-Loeve expansion. PMID:16613481

Gner, U?ur; Arkun, Yaman; Erman, Burak

2006-04-01

99

Matching technique yields optimum LNA performance  

NASA Astrophysics Data System (ADS)

The present article is concerned with a case in which an optimum noise figure and unconditional stability have been designed into a 2.385-GHz low-noise preamplifier via an unusual method for matching the input with a suspended line. The results obtained with several conventional line-matching techniques were not satisfactory. Attention is given to the minimization of thermal noise, the design procedure, requirements for a high-impedance line, a sampling of four matching networks, the noise figure of the single-line matching network as a function of frequency, and the approaches used to achieve unconditional stability.

Sifri, J. D.

1986-02-01

100

Spinning Loop Black Holes  

E-print Network

In this paper we construct four Kerr-like spacetimes starting from the loop black hole Schwarzschild solutions (LBH) and applying the Newman-Janis transformation. In previous papers the Schwarzschild LBH was obtained replacing the Ashtekar connection with holonomies on a particular graph in a minisuperspace approximation which describes the black hole interior. Starting from this solution, we use a Newman-Janis transformation and we specialize to two different and natural complexifications inspired from the complexifications of the Schwarzschild and Reissner-Nordstrom metrics. We show explicitly that the space-times obtained in this way are singularity free and thus there are no naked singularities. We show that the transformation move, if any, the causality violating regions of the Kerr metric far from r=0. We study the space-time structure with particular attention to the horizons shape. We conclude the paper with a discussion on a regular Reissner-Nordstrom black hole derived from the Schwarzschild LBH and...

Caravelli, Francesco

2010-01-01

101

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

102

Optimum interface properties for metal matrix composites  

NASA Technical Reports Server (NTRS)

Due to the thermal expansion coefficient mismatch (CTE) between the fiber and the matrix, high residual sresses exist in metal matrix composite systems upon cool down from processing temperature to room temperature. An interface material can be placed between the fiber and the matrix to reduce the high tensile residual stresses in the matrix. A computer program was written to minimize the residual stress in the matrix subject to the interface material properties. The decision variables are the interface modulus, thickness and thermal expansion coefficient. The properties of the interface material are optimized such that the average distortion energy in the matrix and the interface is minimized. As a result, the only active variable is the thermal expansion coefficient. The optimum modulus of the interface is always the minimum allowable value and the interface thickness is always the maximum allowable value, independent of the fiber/matrix system. The optimum interface thermal expansion coefficient is always between the values of the fiber and the matrix. Using this analysis, a survey of materials was conducted for use as fiber coatings in some specific composite systems.

Ghosn, Louis J.; Lerch, Bradley A.

1989-01-01

103

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, Sinia; Zorc, Davor

2014-01-01

104

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

105

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

106

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.

107

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.

Curran, Carissa

2012-06-11

108

Constricted hysteresis loops in Fe and Ni single crystals  

NASA Astrophysics Data System (ADS)

Magnetic hysteresis loops reflect the variety of magnetic domain structures and have been considered to have normal rectangular or leaf-like shapes in standard ferromagnets such as Fe and Ni metals. We report on observations of constricted hysteresis loops in Fe and Ni single crystals with very low defect densities. The constricted loops were observed below T=150 K and in a medium temperature range from 150 to 430 K in Fe and Ni single crystals, respectively. These constricted loops disappear by weak plastic deformation for both single crystals. The origin of constricted hysteresis loops was explained by eddy current effects under less domain wall pinning due to dislocations.

Takahashi, Seiki; Kobayashi, Satoru; Shishido, Toetsu

2010-11-01

109

Optimum conditions for microbial carbonate precipitation.  

PubMed

The type of bacteria, bacterial cell concentration, initial urea concentration, reaction temperature, the initial Ca(2+) concentration, ionic strength, and the pH of the media are some factors that control the activity of the urease enzyme, and may have a significant impact on microbial carbonate precipitation (MCP). Factorial experiments were designed based on these factors to determine the optimum conditions that take into consideration economic advantage while at the same time giving quality results. Sporosarcina pasteurii strain ATCC 11859 was used at constant temperature (25C) and ionic strength with varying amounts of urea, Ca(2+), and bacterial cell concentration. The results indicate that the rate of ureolysis (k(urea)) increases with bacterial cell concentration, and the bacterial cell concentration had a greater influence on k(urea) than initial urea concentration. At 25 mM Ca(2+) concentration, increasing bacterial cell concentration from 10(6) to 10(8)cells mL? increased the CaCO(3) precipitated and CO(2) sequestrated by over 30%. However, when the Ca(2+) concentration was increased 10-fold to 250 mM Ca(2+), the amount of CaCO(3) precipitated and CO(2) sequestrated increased by over 100% irrespective of initial urea concentration. Consequently, the optimum conditions for MCP under our experimental conditions were 666 mM urea and 250 mM Ca(2+) at 2.310? cells mL? bacterial cell concentration. However, a greater CaCO(3) deposition is achievable with higher concentrations of urea, Ca(2+), and bacterial cells so long as the respective quantities are within their economic advantage. X-ray Diffraction, Scanning Electron Microscopy and Energy Dispersive X-ray analyzes confirmed that the precipitate formed was CaCO(3) and composed of predominantly calcite crystals with little vaterite crystals. PMID:20947128

Okwadha, George D O; Li, Jin

2010-11-01

110

Elevated CO2 and warming effects on CH4 uptake in a semiarid grassland below optimum soil moisture  

Technology Transfer Automated Retrieval System (TEKTRAN)

Semiarid rangelands are a significant global sink for methane (CH4), but this sink strength may be altered by climate change. The uptake of CH4 is sensitive to soil moisture showing a hump-shaped relationship with a distinct optimum soil moisture level. Both CO2 and temperature affect soil moistur...

111

On the optimum control of the wave equation  

NASA Astrophysics Data System (ADS)

Optimal open-loop and closed-loop controllers for distributed parameter systems are developed in this study. The wave equation representing the dynamics of many flexible systems with distributed mass and stiffness, is derived from the extended Hamilton's principle as an equation of motion. A frequency domain strategy is used to obtain the bang-off-bang time-optimal solution for a rest-to-rest maneuver of a slender uniform rod with one or two control inputs. The time-optimal control profiles for the wave equation are derived in closed form. To corroborate the optimality of the control profile derived for the infinite-dimensional model, a series of time-optimal control problems are solved for the finite-dimensional model, with increasing number of flexible modes. In the limit, the controllers show the convergence of the first and final switch of bang-bang controller of the discretized system to the first and final switch of bang-off-bang controller of the distributed parameter system in addition to the convergence of the maneuver time. The maneuver time of the distributed parameter system is compared to that of an equivalent rigid system and the coincidence of the time-optimal controllers of the distributed parameter and rigidized systems is illustrated for certain maneuvers. This implies that the residual energy of the distributed parameter system when it is subject to the time-optimal control profile for the rigidized system is zero for specific maneuvers. Collocated and noncollocated controller for a distributed parameter system whose dynamics is governed by the wave equation are designed using Lyapunov's direct method and a frequency domain approach, respectively. A time-delay relationship is derived in closed form for the noncollocated case. The gains which correspond to a pair of the closed-loop poles entering the right-half complex plane and the gains which correspond to the closed-loop poles being located at the left extreme of the root-locus for each mode are obtained. The overall optimum gain which minimizes a quadratic cost, in the range of the obtained gains for each mode is determined. The effect of sensor location on the observability of the system is investigated when a boundary control actuation is used. Finally, a design approach that results in optimal passive controllers for flexible structures is proposed. The optimal parameters of the passive controllers are determined by minimizing the Integral of the Time Absolute Error (ITAE), subject to control constraints. Passive input-output transfer functions for the plants are obtained by selecting appropriate outputs. The benchmark floating oscillator and two models of overhead cranes are selected to illustrate the design technique. The suspended cable of the overhead crane is first assumed to be rigid and then, the wave equation is used to represent the dynamics of the cable. The simulation results illustrate the effectiveness of the proposed design technique.

Alli, Hasan

112

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

113

FPSO`s today: What is the optimum concept?  

SciTech Connect

FPSO technology over the past years has rapidly evolved from tanker based units with classical mooring systems to purpose-shaped new built vessels equipped with DP assistance, sophisticated permanent turrets or disconnectable mooring systems. FPSO`s cover today a much wider range of applications than a few years ago, and are contemplated for ever more demanding field developments. Selecting the optimum FPSO concept at the beginning of a project is therefore a new step in the early phases of conceptual engineering. This paper describes the main design parameters of current FPSO projects, and evaluates the significance of their influence on the overall design. Several guidelines and insights are provided to help in selecting and combining together technical options available for specific field development cases. The detailed engineering, execution and operational experience gained on recent projects and actual realizations are largely called upon so that pragmatic considerations and recommendations can be suggested for achieving optimized FPSO configurations in a wide range of applications.

Jeannin, O.

1995-12-01

114

Optimum Construction of Heating Coil for Domestic Induction Cooker  

NASA Astrophysics Data System (ADS)

The design and optimization of the parameters of heating coil is very important for the analytical analysis of high frequency inverter fed induction cooker. Moreover, accurate prediction of high frequency winding loss (i.e., losses due to skin and proximity effects) is necessary as the induction cooker used in power electronics applications. At high frequency current penetration in the induction coil circuit is very difficult for conducting wire due to skin-effect. To eradicate the skin effect heating coil is made up of bundle conductor i.e., litz wire. In this paper inductances and AC resistances of a litz-wire are calculated and optimized by considering the input parameters like wire type, shape, number of strand, number of spiral turn, number of twist per feet of heating coil and operating frequency. A high frequency half bridge series resonant mirror inverter circuit is used in this paper and taking the optimum values of inductance and ac resistance the circuit is simulated through PSPICE simulations. It has been noticed that the results are feasible enough for real implementation.

Sinha, Dola; Bandyopadhyay, Atanu; Sadhu, Pradip Kumar; Pal, Nitai

2010-10-01

115

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

116

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!

Ward, Stan

2012-07-31

117

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 500K, 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 0.2nm 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

118

On Optimum Causal Cognitive Spectrum Reutilization Strategy  

E-print Network

In this paper we study opportunistic transmission strategies for cognitive radios (CR) in which causal noisy observation from a primary user(s) (PU) state is available. PU is assumed to be operating in a slotted manner, according to a two-state Markov model. The objective is to maximize utilization ratio (UR), i.e., relative number of the PU-idle slots that are used by CR, subject to interference ratio (IR), i.e., relative number of the PU-active slots that are used by CR, below a certain level. We introduce an a-posteriori LLR-based cognitive transmission strategy and show that this strategy is optimum in the sense of maximizing UR given a certain maximum allowed IR. Two methods for calculating threshold for this strategy in practical situations are presented. One of them performs well in higher SNRs but might have too large IR at low SNRs and low PU activity levels, and the other is proven to never violate the allowed IR at the price of a reduced UR. In addition, an upper-bound for the UR of any CR strategy...

Haghighi, Kasra; Agrell, Erik

2011-01-01

119

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

120

Optimum folding pathways for growing protein chains  

NASA Astrophysics Data System (ADS)

The folding of a protein is studied as it grows residue by residue from the N-terminus and enters an environment that stabilizes the folded state. This mode of folding of a growing chain is different from refolding where the full chain folds from a disordered initial configuration to the native state. We propose a sequential dynamic optimization method that computes the evolution of optimum folding pathways as amino acid residues are added to the peptide chain one by one. The dynamic optimization formulation is deterministic and uses Newton's equations of motion and a Go-type potential that establishes the native contacts and excluded volume effects. The method predicts the optimal energy-minimizing path among all the alternative feasible pathways. As two examples, the folding of the chicken villin headpiece, a 36-residue protein, and chymotrypsin inhibitor 2 (CI2), a 64-residue protein, are studied. Results on the villin headpiece show significant differences from the refolding of the same chain studied previously. Results on CI2 mostly agree with the results of refolding experiments and computational work.

Senturk, Serife; Baday, Sefer; Arkun, Yaman; Erman, Burak

2007-12-01

121

Optimum coding techniques for MST radars  

NASA Technical Reports Server (NTRS)

The optimum coding technique for MST (mesosphere stratosphere troposphere) radars is that which gives the lowest possible sidelobes in practice and can be implemented without too much computing power. Coding techniques are described in Farley (1985). A technique mentioned briefly there but not fully developed and not in general use is discussed here. This is decoding by means of a filter which is not matched to the transmitted waveform, in order to reduce sidelobes below the level obtained with a matched filter. This is the first part of the technique discussed here; the second part consists of measuring the transmitted waveform and using it as the basis for the decoding filter, thus reducing errors due to imperfections in the transmitter. There are two limitations to this technique. The first is a small loss in signal to noise ratio (SNR), which usually is not significant. The second problem is related to incomplete information received at the lowest ranges. An appendix shows a technique for handling this problem. Finally, it is shown that the use of complementary codes on transmission and nonmatched decoding gives the lowest possible sidelobe level and the minimum loss in SNR due to mismatch.

Sulzer, M. P.; Woodman, R. F.

1986-01-01

122

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...

123

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...

124

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...

125

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...

126

Molecule Shapes  

NSDL National Science Digital Library

Explore molecule shapes by building molecules in 3D! How does molecule shape change with different numbers of bonds and electron pairs? Find out by adding single, double or triple bonds and lone pairs to the central atom. Then, compare the model to real molecules!

Simulations, Phet I.; Moore, Emily; Olson, Jonathan; Lancaster, Kelly; Chamberlain, Julia; Perkins, Kathy

2011-10-10

127

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

128

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

129

Optimum wavelengths for two color ranging  

NASA Technical Reports Server (NTRS)

The range uncertainties associated with the refractive atmosphere can be mitigated by the technique of two color, or dual wavelength, ranging. The precision of the differential time of flight (DTOF) measurement depends on the atmospheric dispersion between the two wavelengths, the received pulsewidths and photoelectron counts, and on the amount of temporal averaging. In general, the transmitted wavelengths are not independently chosen but instead are generated via nonlinear optics techniques (harmonic crystals, Raman scattering, etc.) which also determine their relative pulsewidths. The mean received photoelectrons at each wavelength are calculated via the familiar radar link equation which contains several wavelength dependent parameters. By collecting the various wavelength dependent terms, one can define a wavelength figure of merit for a two color laser ranging system. In this paper, we apply the wavelength figure of merit to the case of an extremely clear atmosphere and draw several conclusions regarding the relative merits of fundamental-second harmonic, fundamental-third harmonic, second-third harmonic, and Raman two color systems. We find that, in spite of the larger dispersion between wavelengths, fundamental-third harmonic systems have the lowest figure of merit due to a combination of poor detector performance at the fundamental and poor atmospheric transmission at the third harmonic. The fundamental-second harmonic systems (approximately 700 nm and 350 nm) have the highest figure of merit, but second-third harmonic systems, using fundamental transmitters near 1000 nm, are a close second. Raman-shifted transmitters appear to offer no advantage over harmonic systems because of the relatively small wavelength separation that can be achieved in light gases such as hydrogen and the lack of good ultrashort pulse transmitters with an optimum fundamental wavelength near 400 nm.

Degnan, John J.

1993-01-01

130

Optimum rotationally symmetric shells for flywheel rotors  

DOEpatents

A flywheel rim support formed from two shell halves. Each of the shell halves has a disc connected to the central shaft. A first shell element connects to the disc at an interface. A second shell element connects to the first shell element. The second shell element has a plurality of meridional slits. A cylindrical shell element connects to the second shell element. The cylindrical shell element connects to the inner surface of the flywheel rim. A flywheel rim support having a disc connected an outer diameter of a shaft. Two optimally shaped shell elements connect to the optimally shaped disc at an interface. The interface defines a discontinuity in a meridional slope of said support. A cylindrical shell element connects to the two shell elements. The cylindrical shell element has an outer surface for connecting to the inner surface of the flywheel rim. A flywheel rim casing includes an annular shell connected to the central shaft. The annular shell connects to the flywheel rim. A composite shell surrounds the shaft, annular shell and flywheel rim.

Blake, Henry W. (Oak Ridge, TN)

2000-01-01

131

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.

Researchers, King'S C.

132

Spinning Loop Black Holes  

E-print Network

In this paper we construct four Kerr-like spacetimes starting from the loop black hole Schwarzschild solutions (LBH) and applying the Newman-Janis transformation. In previous papers the Schwarzschild LBH was obtained replacing the Ashtekar connection with holonomies on a particular graph in a minisuperspace approximation which describes the black hole interior. Starting from this solution, we use a Newman-Janis transformation and we specialize to two different and natural complexifications inspired from the complexifications of the Schwarzschild and Reissner-Nordstrom metrics. We show explicitly that the space-times obtained in this way are singularity free and thus there are no naked singularities. We show that the transformation move, if any, the causality violating regions of the Kerr metric far from r=0. We study the space-time structure with particular attention to the horizons shape. We conclude the paper with a discussion on a regular Reissner-Nordstrom black hole derived from the Schwarzschild LBH and then applying again the Newmann-Janis transformation.

Francesco Caravelli; Leonardo Modesto

2010-06-01

133

Spinning loop black holes  

NASA Astrophysics Data System (ADS)

In this paper, we construct four Kerr-like spacetimes starting from the loop black hole (LBH) Schwarzschild solutions and applying the Newman-Janis transformation. In previous papers, the Schwarzschild LBH was obtained replacing the Ashtekar connection with holonomies on a particular graph in a minisuperspace approximation which describes the black hole interior. Starting from this solution, we use a Newman-Janis transformation and restrict our study to two different and natural complexifications inspired from the complexifications of the Schwarzschild and Reissner-Nordstrm metrics. We show explicitly that the spacetimes obtained in this way are singularity free and thus there are no naked singularities. We show that the transformation moves, if any, the causality violating regions of the Kerr metric far from r = 0. We study the spacetime structure paying particular attention to the shape of the horizons. We conclude the paper with a discussion on a regular Reissner-Nordstrm black hole derived from the Schwarzschild LBH and then apply again the Newmann-Janis transformation.

Caravelli, Francesco; Modesto, Leonardo

2010-12-01

134

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

135

Optimum detailed design of reinforced concrete frames using genetic algorithms  

Microsoft Academic Search

This article presents the application of the genetic algorithm to the optimum detailed design of reinforced concrete frames based on Indian Standard specifications. The objective function is the total cost of the frame which includes the cost of concrete, formwork and reinforcing steel for individual members of the frame. In order for the optimum design to be directly constructible without

V. Govindaraj; J. V. Ramasamy

2007-01-01

136

On the design of optimum radar waveforms for clutter rejection  

Microsoft Academic Search

The problem to be considered in this paper is that of designing radar signals and receivers that are optimum for detecting a point target masked by a background of clutter returns and thermal noise. The problem of choosing an optimum signal when no constraints are placed on the type of signals allowed is discussed briefly, but the remainder of the

D. DeLong; E. Hofstetter

1967-01-01

137

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

138

Optimum aerodynamic design via boundary control  

NASA Technical Reports Server (NTRS)

These lectures describe the implementation of optimization techniques based on control theory for airfoil and wing design. In previous studies it was shown that control theory could be used to devise an effective optimization procedure for two-dimensional profiles in which the shape is determined by a conformal transformation from a unit circle, and the control is the mapping function. Recently the method has been implemented in an alternative formulation which does not depend on conformal mapping, so that it can more easily be extended to treat general configurations. The method has also been extended to treat the Euler equations, and results are presented for both two and three dimensional cases, including the optimization of a swept wing.

Jameson, Antony

1994-01-01

139

Shapely Lines  

NSDL National Science Digital Library

This activity gives students practice drawing straight lines with a ruler and looking for and categorizing shapes, for example, by the number of sides in polygons. The Teachers' Notes page includes suggestions for implementation, discussion questions and ideas for extension.

2010-06-01

140

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

141

Simulations of gyrosynchrotron microwave emission from an oscillating magnetic loop  

NASA Astrophysics Data System (ADS)

Radio observations of solar flares often reveal various periodic or quasi-periodic oscillations. Most likely, these oscillations are caused by MHD oscillations of flaring loops which modulate the radio emission via variations of the magnetic field and electron concentration. We perform numerical simulations of gyrosynchrotron radiation from a toroidal-shaped magnetic loop containing sausage-mode MHD oscillations. Different parameters of the loop and MHD oscillations and different loop orientations are considered. The simulation results are compared with the observations of the Nobeyama Radioheliograph.

Kuznetsov, Alexey; Reznikova, Veronika; Van Doorsselaere, Tom; Antolin, Patrick

142

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

2014-12-01

143

Shape It Up!!!  

NSDL National Science Digital Library

Today we are going to review the shapes we have been learning! Please practice your knowledge of shapes by doing these three activities: Geometric shapes Another Shape Activity with Balances Make a picture with shapes Have fun with Shapes!!! ...

Lucherini, Miss

2007-11-10

144

Investigation of earthquake factor for optimum tuned mass dampers  

NASA Astrophysics Data System (ADS)

In this study the optimum parameters of tuned mass dampers (TMD) are investigated under earthquake excitations. An optimization strategy was carried out by using the Harmony Search (HS) algorithm. HS is a metaheuristic method which is inspired from the nature of musical performances. In addition to the HS algorithm, the results of the optimization objective are compared with the results of the other documented method and the corresponding results are eliminated. In that case, the best optimum results are obtained. During the optimization, the optimum TMD parameters were searched for single degree of freedom (SDOF) structure models with different periods. The optimization was done for different earthquakes separately and the results were compared.

Nigdeli, Sinan Melih; Bekda?, Gebrail

2012-09-01

145

Super Shapes  

NSDL National Science Digital Library

We\\'ll be working with some different shapes and learning how to use them. Explore the following links to learn some more about what we\\'ll be working on in this unit. Think you already know something? Find out how much you know with this page. Look up information on the Fact Sheet, try it for yourself with the Activity, and test yourself with the Test. Geometric Shapes Do triangles trick you? Here you can practice making them do what you want! Triangles Classifying Triangles What\\'s ...

Miss M.

2007-10-08

146

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.

Jordan, Catherine

2012-01-01

147

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

148

50 CFR 648.20 - Maximum optimum yield (OYs).  

Code of Federal Regulations, 2010 CFR

...Management Measures for the Atlantic Mackerel, Squid, and Butterfish Fisheries 648.20 Maximum optimum yield (OYs...associated with a fishing mortality rate of FMSY . (d) Butterfishthe catch associated with a fishing mortality rate of...

2010-10-01

149

50 CFR 648.20 - Maximum optimum yield (OYs).  

Code of Federal Regulations, 2011 CFR

...Management Measures for the Atlantic Mackerel, Squid, and Butterfish Fisheries 648.20 Maximum optimum yield (OYs...associated with a fishing mortality rate of FMSY . (d) Butterfishthe catch associated with a fishing mortality rate of...

2011-10-01

150

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

151

CELLULOSE SHAPES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Recent high resolution fiber diffraction studies of four forms of crystalline cellulose are reviewed. All have two-fold screw-axis symmetry, There is little difference among the various chain shapes in the crystal environment, except for the O6 position and the hydrogen bonding schemes. The parallel...

152

Designing a 'Near Optimum' Cooling-Water System  

E-print Network

outlet temperature is the "Achilles heel" of this study and the reason why only a "near optimum," rather than a truly optimized, cooling system is attained. T, Exchanger Pip; ng Tower design ----design--- design Typical systam demonstrates thr..., April 26-29, 1981 This example shows why the cooling-tower outlet temperature is the "Achilles heel" of this study. To be rigorous, the fifth heat exchanger should be resized, using the optimum coolant outlet tempera ture calculated...

Crozier, R. A., Jr.

1981-01-01

153

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

154

Optimum detailed design of reinforced concrete frames using genetic algorithms  

NASA Astrophysics Data System (ADS)

This article presents the application of the genetic algorithm to the optimum detailed design of reinforced concrete frames based on Indian Standard specifications. The objective function is the total cost of the frame which includes the cost of concrete, formwork and reinforcing steel for individual members of the frame. In order for the optimum design to be directly constructible without any further modifications, aspects such as available standard reinforcement bar diameters, spacing requirements of reinforcing bars, modular sizes of members, architectural requirements on member sizes and other practical requirements in addition to relevant codal provisions are incorporated into the optimum design model. The produced optimum design satisfies the strength, serviceability, ductility, durability and other constraints related to good design and detailing practice. The detailing of reinforcements in the beam members is carried out as a sub-level optimization problem. This strategy helps to reduce the size of the optimization problem and saves computational time. The proposed method is demonstrated through several example problems and the optimum results obtained are compared with those in the available literature. It is concluded that the proposed optimum design model can be adopted in design offices as it yields rational, reliable, economical, time-saving and practical designs.

Govindaraj, V.; Ramasamy, J. V.

2007-06-01

155

A Geometry-Based Parameterization Method for Shape Design of Elastic Solids  

Microsoft Academic Search

One of the major difficulties in structural shape optimal design is to create a design model by parameterizing a geometric model. Shape design parameterization is more complicated and difficult to handle than sizing design parameterization. First, the optimum shape is highly dependent on the design parameterization selected. An inappropriate design parameterization may result in an impractical design. On the other

Kuang-Hua Chang; Kyung K. Choi

1992-01-01

156

Wilson Loops @ 3-Loops in Special Kinematics  

E-print Network

We obtain a compact expression for the octagon MHV amplitude / Wilson loop at 3 loops in planar N=4 SYM and in special 2d kinematics in terms of 7 unfixed coefficients. We do this by making use of the cyclic and parity symmetry of the amplitude/Wilson loop and its behaviour in the soft/collinear limits as well as in the leading term in the expansion away from this limit. We also make a natural and quite general assumption about the functional form of the result, namely that it should consist of weight 6 polylogarithms whose symbol consists of basic cross-ratios only (and not functions thereof). We also describe the uplift of this result to 10 points.

Paul Heslop; Valentin V. Khoze

2011-09-01

157

Wilson Loops @ 3-Loops in Special Kinematics  

E-print Network

We obtain a compact expression for the octagon MHV amplitude / Wilson loop at 3 loops in planar $\\cN$=4 SYM and in special 2d kinematics in terms of 7 unfixed coefficients. We do this by making use of the cyclic and parity symmetry of the amplitude/Wilson loop and its behaviour in the soft/collinear limits as well as in the leading term in the expansion away from this limit. We also make a natural and quite general assumption about the functional form of the result, namely that it should consist of weight 6 polylogarithms whose symbol consists of basic cross-ratios only (and not functions thereof). We also describe the uplift of this result to 10 points.

Heslop, Paul

2011-01-01

158

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.

159

Improving disturbance rejection of PID controllers by means of the magnitude optimum method.  

PubMed

The magnitude optimum (MO) method provides a relatively fast and non-oscillatory closed-loop tracking response for a large class of process models frequently encountered in the process and chemical industries. However, the deficiency of the method is poor disturbance rejection performance of some processes. In this paper, disturbance rejection performance of the PID controller is improved by applying the "disturbance rejection magnitude optimum" (DRMO) optimisation method, while the tracking performance has been improved by a set-point weighting and set-point filtering PID controller structure. The DRMO tuning method requires numerical optimisation for the calculation of PID controller parameters. The method was applied to two different 2-degrees-of-freedom PID controllers and has been tested on several different representatives of process models and one laboratory set-up. A comparison with some other tuning methods has shown that the proposed tuning method, with a set-point filtering PID controller, is quite efficient in improving disturbance rejection performance, while retaining tracking performance comparable with the original MO method. PMID:19733851

Vranci?, Damir; Strmcnik, Stanko; Kocijan, Jus; de Moura Oliveira, P B

2010-01-01

160

Shape Up.  

E-print Network

)OC TA24S.7 173 1.1217 , 8-1217 , Texas Agricultural Extension Service ? The Texas A&M university system Daniel C. Pfannstlel, Director ? college Station, Texas [Blank Page in Original Bulletin] 8-1217 SHAPE UP Physical fitness, figure..., and Emma S. Gibbons, Instruc tor, Department of Health and Physical Education, The Texas A&M University System. 11 Adapted from a publication developed by the Cooperative Exten sion Service, University of Georgia College of Agriculture, Athens...

Anonymous,

1979-01-01

161

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 proteinthe nonspecific nucleoid protein HUincrease 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

162

What controls DNA looping?  

PubMed

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

163

Falling Loop Model  

NSDL National Science Digital Library

The EJS Falling Loop Model shows a conducting loop falling out of a uniform magnetic field. Users can change the size and orientation of the loop. If Ejs is installed, right-clicking within the plot and selecting Open Ejs Model from the pop-up menu item allows for editing of the model. The Falling Loop model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_em_FallingLoop.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Cox, Anne

2009-09-24

164

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

165

Digital Parallel Processor Array for Optimum Path Planning  

NASA Technical Reports Server (NTRS)

The invention computes the optimum path across a terrain or topology represented by an array of parallel processor cells interconnected between neighboring cells by links extending along different directions to the neighboring cells. Such an array is preferably implemented as a high-speed integrated circuit. The computation of the optimum path is accomplished by, in each cell, receiving stimulus signals from neighboring cells along corresponding directions, determining and storing the identity of a direction along which the first stimulus signal is received, broadcasting a subsequent stimulus signal to the neighboring cells after a predetermined delay time, whereby stimulus signals propagate throughout the array from a starting one of the cells. After propagation of the stimulus signal throughout the array, a master processor traces back from a selected destination cell to the starting cell along an optimum path of the cells in accordance with the identity of the directions stored in each of the cells.

Kremeny, Sabrina E. (Inventor); Fossum, Eric R. (Inventor); Nixon, Robert H. (Inventor)

1996-01-01

166

Tool Geometry for Friction Stir WeldingOptimum 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

167

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

168

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

169

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

170

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.

Moncls, M. A.; Molina-Aldaregua, 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, Technick 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

171

Optimum camera placement considering camera specification for security monitoring  

Microsoft Academic Search

AbstractWe,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

172

Hydrofoils: optimum lift-off speed for sailboats.  

PubMed

For a hydrofoil sailboat there is a unique optimum lift-off speed. Before this speed is reached, if there are no parasitic vertical hydrofoil appendages, the submerged or partially submerged hydrofoils increase drag and degrade performance. As soon as this speed is reached and the hydrofoils are fully and promptly deployed, the performance of a hydrofoil-borne craft is significantly improved. At speeds exceeding optimum lift-off speed, partially submerged hydrofoils impair performance if there is no significant effect of loading on the hydrofoil lift-to-drag ratio. PMID:17756335

Baker, R M

1968-12-13

173

Optimum profiles for asymmetrical longitudinal fins in annular ducts  

SciTech Connect

In the present work the geometry of annular ducts with asymmetrical longitudinal fins is optimized in order to enhance the heat transfer under laminar coolant flow conditions. The heat transferred is also maximized for a given amount of material or hydraulic resistance. Polynomial profiles are assigned to the two lateral fin surfaces. Velocity and temperature distributions on the annular duct cross section are determined with the help of a finite-element model. A global heat transfer coefficient and an equivalent Nusselt number are then calculated. Lastly, optimum asymmetrical fins obtained by means of a genetic algorithm are shown for different situations and their performance is compared with those of optimum symmetrical fins.

Fabbri, G.

2000-04-01

174

Conservation of closed loops.  

PubMed

The closed loop hypothesis of Berezovsky and Trifonov implicates the closure of loops of length 25-35 through hydrophobic interactions at the 'locks' as a key event in protein folding. The hypothesis is supported by published analyses of nine major superfolds. Here, we have generated multiple sequence alignments for the nine superfolds with PDB codes lthb, 1ilb, 256b, 2rhe, 1aps, 2stv, 4fxn (2fox), lubq and 7tim and have analysed the degree of conservation at the loop ends. Seventy percent of these loop ends are found to be well conserved and the peak in the distribution of distances between these well conserved regions lies at around 25 residues; both observations are consistent with the Berezovsky and Trifonov's hypothesis. PMID:17459747

Yew, Boon K; Chintapalli, Sree V; Upton, Graham G C; Reynolds, Christopher A

2007-10-01

175

Faraday Loop Model  

NSDL National Science Digital Library

The EJS Faraday Loop Model shows a conducting loop in a time-dependent constant magnetic field. The model is initially incomplete and students must complete the model by adding the appropriate equations. If Ejs is installed, right-clicking within the plot and selecting Open Ejs Model from the pop-up menu item allows for editing of the model. The Faraday Loop model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_em_FaradayLoop.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Cox, Anne

2009-06-26

176

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,

177

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

178

Closed-Loop Systems  

NSDL National Science Digital Library

Teachers' Domain presents this interactive lesson on closed-loop systems, which includes an animation that describes the typical components of a closed-loop system (error detector, controller, actuator, and measurement device), and describes the input and output signals for each component. The interactive lesson includes three sections: introduction, system overview, and adjustment scenarios. The activity includes 18 screens with reading materials as well as a supplemental background essay, discussion questions, and standards alignment from Teachers' Domain.

2010-10-11

179

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

180

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.

181

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

182

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

183

Digital methods of the optimum processing of radar signals  

Microsoft Academic Search

In book questions of use\\/application of digital computers for optimum processing of radar signals are examined. Primary attention is given to the detection of signals from the targets, hidden by interferences, and to the determination of the target coordinates. Is described the work of the simplest diagrams of working\\/treatment, their operating principle, and also work of some nodes of digital

S. V. Samsonenko

1985-01-01

184

Optimum Income Taxation and Layo Taxes Pierre Cahucy  

E-print Network

Optimum Income Taxation and Layo¤ Taxes¤ Pierre Cahucy CREST-INSEE, Université Paris 1, CEPR, IZA to unemployment. It is shown that optimal tax schemes comprise both payroll and layo¤ taxes when the state provides public unemployment insurance and aims at redistributing income. The optimal layo¤ tax is equal

Boyer, Edmond

185

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

186

Measuring the Aerosol Characteristics of the Optimum Insecticide Spray  

Microsoft Academic Search

Spray characteristics were investigated to determine the optimum aerosol spray for insecticides while considering volatile organic carbon (VOC) reduction. Our ultimate goal is to improve the efficiency of killing insects while using less aerosol spray, which contains chemicals, oil, and dimethyl ether (DME). The chemical content of the aerosol is greatly reduced in the attachment region 1-2 m from the

Yuji Ikeda; Atsushi Nishiyama; Seung Mo Kim; Yoshihiro Horibe; Shigeki Takaki

187

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...

188

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

189

Neural Networks Arbitration for Optimum DCT Image Compression  

Microsoft Academic Search

Image compression using Discrete Cosine Transform (DCT) is one of the simplest commonly used compression methods. The quality of compressed images, however, is marginally reduced at higher compression ratios due to the lossy nature of DCT compression, thus, the need for finding an optimum DCT compression ratio. An ideal image compression system must yield high quality compressed images with good

Adnan Khashman; Kamil Dimililer

2007-01-01

190

Finding Globally Optimum Solutions in Antenna Optimization Problems  

E-print Network

as the optimization variables. This is particularly useful in designing on-chip smart antennas, where thousands in designing smart antennas. Description of the Problem Let us consider the problem in Figure 1, where a dipoleFinding Globally Optimum Solutions in Antenna Optimization Problems Aydin Babakhani*, Javad Lavaei

Hajimiri, Ali

191

Optimum Treatment Allocation for Dualobjective Clinical Trials with Binary Outcomes  

E-print Network

Optimum Treatment Allocation for Dual­objective Clinical Trials with Binary Outcomes Wei Zhu, Weng One common problem in many randomized clinical trials is how to assign patients to several treatment, although in reality, there are usually several objectives in a clinical trial. In this paper, optimal

New York at Stoney Brook, State University of

192

Optimum Treatment Allocation in Clinical Trials Using Heteroscedastic Linear Models  

E-print Network

Optimum Treatment Allocation in Clinical Trials Using Heteroscedastic Linear Models Wei Zhu, Weng In clinical trials comparing several treatments, it is often the case that the response variance varies from and Donev, 1992; Fe­ dorov, 1972; Kiefer, 1974, 1985; Silvey, 1980) to design a randomized clinical trial

New York at Stoney Brook, State University of

193

Large and small scale sensitivity analysis of optimum estimation algorithms  

Microsoft Academic Search

This paper presents the derivation and evaluation of algorithms for error analysis, large and small scale sensitivity of optimum filtering and fixed interval smoothing solutions to linear estimation problems. Model errors as well as ignorance of plant and measurement noise covariance matrices are considered. Results are presented for a simple scalar problem and for the problem of state estimation in

R. Griffin; A. Sage

1968-01-01

194

Optimum Design of Disease-modifying Trials on Alzheimer's Disease  

Microsoft Academic Search

Randomized start and withdrawal designs have been recently proposed to test the disease-modifying agents on Alzheimer's disease (AD). This article provides methods to determine the optimum parameters for these designs. A general linear mixed effects model is proposed. This model employs a piecewise linear growth pattern for those in the delayed treatment or early withdrawal arm, and incorporates a potential

Chengjie Xiong; Jingqin Luo; Feng Gao; Ling Chen; Yan Yan

2012-01-01

195

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.

196

OPTIMUM ACTUATOR SELECTION WITH A GENETIC ALGORITHM FOR AIRCRAFT CONTROL  

E-print Network

OPTIMUM ACTUATOR SELECTION WITH A GENETIC ALGORITHM FOR AIRCRAFT CONTROL JAMES L. ROGERS NASA Langley Research Center ABSTRACT: The placement of actuators on a wing determines the control axes, while minimizing the coupling. For example, the desired actuators produce a pure roll moment

Coello, Carlos A. Coello

197

Optimum Wireless Powering of Sensors Embedded in Concrete  

Microsoft Academic Search

The optimization of wireless powering of sensors embedded in concrete is studied here. Our analytical results focus on calculating the transmission loss and propagation loss of RF waves penetrating into concrete at different humidity conditions. Specifically, this analysis leads to the identification of an optimum frequency range within 2080 MHz that is validated through antenna coupling full-wave EM simulations. Also,

Shan Jiang; Stavros V. Georgakopoulos

2012-01-01

198

Optimum power transmission of wireless sensors embedded in concrete  

Microsoft Academic Search

We present the feasibility and optimization of wireless powering of sensors embedded in concrete that relies on a plane wave propagation model. Transmission loss and propagation loss of RF wave penetrating into concrete at different humidity conditions are calculated for various frequencies. An optimum frequency range within 20-80 MHz is identified for the wireless power transmission and is validated through

Shan Jiang; Stavros V. Georgakopoulos

2010-01-01

199

Optimum displacement for compound image generation in medical ultrasound  

Microsoft Academic Search

Incoherent averaging of measurements made at different look directions can be used to reduce speckle noise in medical ultrasound images. An analytic expression for the correlation between two measurements made at different spatial positions is derived. Using this expression, the optimum aperture displacement for efficient incoherent averaging (i.e. compounding) is computed and found to equal approximately one-half the aperture length

M. O'Donnell; S. D. Silverstein

1988-01-01

200

Selection of Wavelengths for Optimum Precision in Simultaneous Spectrophotometric Determinations.  

ERIC Educational Resources Information Center

Although many textbooks include a description of simultaneous determinations employing absorption spectrophotometry and treat the mathematics necessary for analytical quantitations, treatment of analytical wavelength selection has been mostly qualitative. Therefore, a general method for selecting wavelengths for optimum precision in simultaneous

DiTusa, Michael R.; Schilt, Alfred A.

1985-01-01

201

OPTIMUM UPDATE STEP FOR MOTION-COMPENSATED LIFTED WAVELET CODING  

E-print Network

methods have been compared to compute backward motion fields for the update step [5], and some authors (eOPTIMUM UPDATE STEP FOR MOTION-COMPENSATED LIFTED WAVELET CODING (Invited Paper) Bernd Girod, the update step typically reverses the motion vectors from the prediction step. Where motion compensation

Girod, Bernd

202

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

203

Optimum properties of working fluids for solar powered heat pumps  

Microsoft Academic Search

In this study, the effect of the thermodynamic properties of the working fluid on the performance of a solar powered heat pump has been analyzed. The system consists of a vapor compression cooling or heating cycle combined with a Rankine power cycle. Values of the input fluid properties which result in optimum efficiencies have been determined for upper temperatures of

L. I. Stiel; R. A. Allen; K. P. Murphy

1975-01-01

204

Optimum Fuel Cell Utilization with Multilevel Inverters Burak Ozpineci1  

E-print Network

Optimum Fuel Cell Utilization with Multilevel Inverters Burak Ozpineci1 1 Oak Ridge National. This inevitable decrease, which is caused by internal losses, reduces the utilization factor of the fuel cells at low loads. Additionally, the converters fed by these fuel cells have to be derated to accommodate

Tolbert, Leon M.

205

Optimum mesh grading for finite-difference method  

Microsoft Academic Search

The coarseness error of the finite-difference (FD) method is studied analyzing a typical planar waveguide and a rectangular coaxial geometry. Results for equidistant and graded mesh are compared in terms of accuracy and numerical efforts. Because of the field singularities involved a graded mesh proves to be superior compared to the equidistant case. A grading strategy with optimum efficiency is

W. Heinrich; K. Beilenhoff; P. Mezzanotte; L. Roselli

1996-01-01

206

Economically Optimum Irrigation Patternsfor Grain Sorghum Production: Texas High Plains  

E-print Network

to be applied during specified periods of the production process, a stochastic open-loop feedback control policy was built into a grain sorghum growth simulation model. The control policy operated under the basis of constant revision of the expectations...

Zavaleta, L. R.; Lacewell, R. D.; Taylor, C. R.

207

Research on the optimum length-diameter ratio of the charge of a multimode warhead  

NASA Astrophysics Data System (ADS)

This paper outlines our research on a multimode warhead in which we adopted center point and annular initiation modes to form multimode penetrators. Using LS-DYNA software, we studied the effect of the configuration parameters, namely the length/diameter ratio of the shaped charge, on the formation parameters, such as the velocity and length/diameter ratio, of multimode penetrators. We found that when the charge length was in the range of 0.9-1.2 times the charge diameter, the same structure of shaped charge can form suitable multimode penetrators. Either an explosively formed penetrator (EFP) or a long stretchy rod-shaped EFP penetrator can be formed. We establish an optimum charge length for penetrator formation of 1.4 times the charge diameter. Simulation results were validated using X-ray imaging experiments and they were in good agreement. The results found that by increasing the charge length from 0.9 to 1.4 times the charge diameter, the penetration depth of the EFP increased by 74.5%, while increasing the charge length from 1.4 to 1.6 times the charge diameter only increased the penetration depth by 1.9%.

Li, Weibing; Wang, X.; Li, Wenbin; Zheng, Y.

2012-05-01

208

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

209

An Extended Nonlinear-Based Method for Optimum Cutting Pattern Generation of Membrane Structures  

NASA Astrophysics Data System (ADS)

The cutting pattern for membrane structures obtained by using the geodesic line method or flattening technique does not allow the actual stresses in the structures to be specified. As a result, the occurrence of surface wrinkles may form under service loading. In this paper, a method for determining an optimum cutting pattern which accounts for the designed stresses of the membrane structures is presented. Using the displacements of the 3-D surface as the key variables, the method proposed utilizes a nonlinear analysis technique based upon the second Piola-Kirchhoff stress tensor, Green strain tensor and Saint Venant-Kirchhoff hyperelastic material. The genetic algorithm is also adopted to solve the optimization problem. To verify the validation of the existing method, a cone shape membrane structure was analyzed. By using the proposed method, the deviation of the actual membrane stresses from the assumed design stresses could be reduced.

Punurai, W.; Tongpool, W.; Saardwong, W.

2010-05-01

210

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

211

Physical mechanisms redirecting cell polarity and cell shape  

PubMed Central

Summary The fission yeast Schizosaccharomyces pombe has a cylindrical rod-shape that is organized and maintained by interactions between the microtubule, cell membrane, and actin cytoskeleton; i.e., microtubules deliver factors to the cell tips that subsequently recruit the actin machinery to direct localized cell growth [1]. Mutations affecting any components in this pathway lead to bent, branched, or round cells [2]. In this context, the cytoskeleton controls cell polarity and thus dictates cell shape. Here, we use soft-lithography techniques to construct microfluidic channels in order to control the shape of cells. We show that by physically forcing wildtype rod-shaped cells to grow bent, they will re-organize their cytoskeleton and re-direct cell polarity to make new ectopic cell tips. In addition, by physically forcing bent or round mutant cells to conform to the wildtype rod-shape, cells will reverse their mutational phenotypes by re-organizing their cytoskeleton to maintain proper wildtype-like microtubule, cell membrane proteins, and actin localizations. Our study provides direct evidence that the cytoskeleton controls cell polarity and cell shape and demonstrates that cell shape also controls the organization of the cytoskeleton, in a feedback loop. We present a model of the feedback loop which explains how fission yeast cells maintain a rod-shape, and how perturbation of specific parameters of the loop can lead to different cell shapes. PMID:19026544

Terenna, Courtney R.; Makushok, Tatyana; Velve-Casquillas, Guilhem; Baigl, Damien; Chen, Yong; Bornens, Michel; Paoletti, Anne; Piel, Matthieu; Tran, Phong T.

2010-01-01

212

A methodology for selecting optimum organizations for space communities  

NASA Technical Reports Server (NTRS)

This paper suggests that a methodology exists for selecting optimum organizations for future space communities of various sizes and purposes. Results of an exploratory study to identify an optimum hypothetical organizational structure for a large earth-orbiting multidisciplinary research and applications (R&A) Space Base manned by a mixed crew of technologists are presented. Since such a facility does not presently exist, in situ empirical testing was not possible. Study activity was, therefore, concerned with the identification of a desired organizational structural model rather than the empirical testing of it. The principal finding of this research was that a four-level project type 'total matrix' model will optimize the effectiveness of Space Base technologists. An overall conclusion which can be reached from the research is that application of this methodology, or portions of it, may provide planning insights for the formal organizations which will be needed during the Space Industrialization Age.

Ragusa, J. M.

1978-01-01

213

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

214

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

215

Optimum shell separation for closed axial cylindrical magnetic shields  

NASA Astrophysics Data System (ADS)

The effect of shell separation on the axial shielding with closed double-shell cylindrical shields is investigated numerically. It is found that the optimum shell separation for practical, equal-thickness shields of the above type is considerably smaller than that for transverse spherical and infinitely long cylindrical shields: in most cases, air gaps equal 5%-10% of the inner shell diameter are wide enough to bring the shielding to 90% of its maximum. This indicates that closely spaced axial shields can be used without much sacrifice in performance. Taking into account the computed optimum shell separation for double-shell shields, one can easily optimize and design a compact and effective multishell shield. Based on the numerical study, an analytical approximation is suggested for the axial shielding with narrowly spaced double-shell cylindrical shields.

Paperno, Eugene; Peliwal, Saee; Romalis, Michael V.; Plotkin, Anton

2005-05-01

216

Operational characteristics of a 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 the flat disk shaped evaporator, 10 mm thick and 30 mm in diameter, for the thermal control of the compact electronic equipments. The loop was made of copper with nickel wick and water as the working fluid. Detailed study was conducted on the start-up reliability

Randeep Singh; Aliakbar Akbarzadeh; Masataka Mochizuki

2008-01-01

217

Wilson-loop instantons  

NASA Technical Reports Server (NTRS)

Wilson-loop symmetry breaking is considered on a space-time of the form M4 x K, where M4 is a four-dimensional space-time and K is an internal space with nontrivial and finite fundamental group. It is shown in a simple model that the different vacua obtained by breaking a non-Abelian gauge group by Wilson loops are separated in the space of gauge potentials by a finite energy barrier. An interpolating gauge configuration is then constructed between these vacua and shown to have minimum energy. Finally some implications of this construction are discussed.

Lee, Kimyeong; Holman, Richard; Kolb, Edward W.

1987-01-01

218

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. Chacn; F. Borondo

2014-09-15

219

The application of vortex theory to the optimum swept propeller  

NASA Technical Reports Server (NTRS)

It is shown that an optimum propeller generating a swept wake must satisfy the Betz condition, at least to a first order. A numerical solution for swept propellers generating a rigid helicoidal wake is formulated and some results are presented. These results indicate that sweep has a significant effect on Goldstein's kappa factor, particularly at high advance ratios typical of those at which advanced turboprops operate.

Mccormick, B. W.

1984-01-01

220

Near-optimum decoding of product codes: block turbo codes  

Microsoft Academic Search

This paper describes an iterative decoding algorithm for any product code built using linear block codes. It is based on soft-input\\/soft-output decoders for decoding the component codes so that near-optimum performance is obtained at each iteration. This soft-input\\/soft-output decoder is a Chase decoder which delivers soft outputs instead of binary decisions. The soft output of the decoder is an estimation

Ramesh Mahendra Pyndiah

1998-01-01

221

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

222

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...

223

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

224

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

225

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

226

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

227

Development of agri-pellet production cost and optimum size.  

PubMed

Minimum production cost and optimum plant size were determined for pellet plants using agricultural biomass residue from wheat, barley and oats. Three scenarios involving minimum, average and maximum yields of straw were considered for developing a techno-economic model. The life cycle cost of producing pellets in Western Canada was estimated. The economically optimum size of production plant for the three yield scenarios in tonne year(-1) were 70,000, 150,000 and 150,000, respectively. The corresponding costs of production per tonne are $170.89, $129.42 and $122.17, respectively. However, the cost of pellets does not change much for capacities over 70,000 tonne year(-1) for both the average and maximum yields. The optimum size is same for both average and maximum yield cases. Sensitivity analyses have showed that the total cost of pellet production is most sensitive to field cost followed by transportation cost. Currently, the cost of energy from agri-pellets is higher than that of energy from natural gas. PMID:20189801

Sultana, Arifa; Kumar, Amit; Harfield, Don

2010-07-01

228

Optimum Waveforms for Differential Ion Mobility Spectrometry (FAIMS)  

PubMed Central

Differential mobility spectrometry or field asymmetric waveform ion mobility spectrometry (FAIMS) is a new tool for separation and identification of gas-phase ions, particularly in conjunction with mass-spectrometry. In FAIMS, ions are filtered by the difference between mobilities in gases (K) at high and low electric field intensity (E) using asymmetric waveforms. An infinite number of possible waveform profiles make maximizing the performance within engineering constraints a major issue for FAIMS technology refinement. Earlier optimizations assumed the non-constant component of mobility to scale as E2, producing the same result for all ions. Here we show that the optimum profiles are defined by the full series expansion of K(E) that includes terms beyond the 1st that is proportional to E2. For many ion/gas pairs, the first two terms have different signs, and the optimum profiles at sufficiently high E in FAIMS may differ substantially from those previously reported, improving the resolving power by up to 2.2 times. This situation arises for some ions in all FAIMS systems, but becomes more common in recent miniaturized devices that employ higher E. With realistic K(E) dependences, the maximum waveform amplitude is not necessarily optimum and reducing it by up to ?20 30% is beneficial in some cases. The present findings are particularly relevant to targeted analyses where separation depends on the difference between K(E) functions for specific ions. PMID:18585054

Shvartsburg, Alexandre A.; Smith, Richard D.

2009-01-01

229

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

230

Optimum Aerodynamic Design using the NavierStokes Equations  

E-print Network

differential equations of the flow, with the boundary shape acting as the control. The Frechet derivative of pressure distribution that will provide the desired aerodynamic performance. This motivates the introduction of inverse problems in which the shape corresponding to a specified pressure distribution

Jameson, Antony

231

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

232

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.

233

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

234

A Generalized Theory of DNA Looping and Cyclization  

NASA Astrophysics Data System (ADS)

We have developed a semi-analytic method for calculating the Stockmayer Jacobson J-factor for protein mediated DNA loops. The formation of DNA loops on the order of a few persistence lengths is a key component in many biological regulatory functions. The binding of LacI protein within the Lac Operon of E.coli serves as the canonical example for loop regulated transcription. We use a non-linear rod model to determine the equilibrium shape of the inter-operator DNA loop under prescribed binding constraints while taking sequence-dependent curvature and elasticity into account. Then we construct a Hamiltonian that describes thermal fluctuations about the open and looped equilibrium states, yielding the entropic and enthalpic costs of loop formation. Our work demonstrates that even for short sequences of the order one persistence length, entropic terms contribute substantially to the J factor. We also show that entropic considerations are able to determine the most favorable binding topology. The J factor can be used to compare the relative loop lifetimes of various DNA sequences, making it a useful tool in sequence design. A corollary of this work is the computation of an effective torsional persistence length, which demonstrates how torsion bending coupling in a constrained geometry affects the conversion of writhe to twist.

Wilson, David; Lillian, Todd; Perkins, Noel; Tkachenko, Alexei; Meiners, Jens-Christian

2010-03-01

235

[U-shaped free jejunum transplant].  

PubMed

Reconstruction of the oro and hypopharynx has specific difficulties due to their wide diameters. Seven patients underwent reconstruction with a free U-shaped jejunal transplant, after circular pharyngolaryngectomy for hypopharyngeal cancer invading the oropharynx. This transplant included a side-to-side anastomosis between the two limbs of the jejunal loop. This transplant allowed reconstruction of the upper digestive tract after wide carcinologic resection of the pharynx. The U-shaped jejunal transplant facilitated the upper anastomosis, especially at the upper part where the resection involved the oropharynx. It formed a reservoir behind the tongue, and avoided nasal reflux. The best indications are large resections involving the oropharynx. PMID:9951097

Germain, M A; Julieron, M; Trotoux, J; Filippetti, M; Santoro, E; Marzetti, F

1998-01-01

236

Sink strength calculations of dislocations and loops using OKMC  

NASA Astrophysics Data System (ADS)

We calculate the sink strength of dislocations and toroidal absorbers using Object Kinetic Monte Carlo and compare with the theoretical expressions. We get good agreement for dislocations and loop-shaped absorbers of 3D migrating defects, provided that the volume fraction is low, and fair agreements for dislocations with 1D migrating defects. The master curve for the 3D to 1D transition is well reproduced with loop-shaped absorbers and fairly well with dislocations. We conclude that, on the one hand, the master curve is correct for a wide range of sinks and that, on the other, OKMC techniques inherently take correctly into account the strengths of sinks of any shape, provided that an effective way of appropriately inserting the sinks to be studied can be found.

Jansson, V.; Malerba, L.; De Backer, A.; Becquart, C. S.; Domain, C.

2013-11-01

237

COLD TEST LOOP INTEGRATED TEST LOOP RESULTS  

SciTech Connect

A testing facility (Cold Test Loop) was constructed and operated to demonstrate the efficacy of the Accelerated Waste Retrieval (AWR) Project's planned sluicing approach to the remediation of Silos 1 and 2 at the Fernald Environmental Management Project near Cincinnati, Ohio. The two silos contain almost 10,000 tons of radium-bearing low-level waste, which consists primarily of solids of raffinates from processing performed on ores from the Democratic Republic of Congo (commonly referred to as ''Belgium Congo ores'') for the recovery of uranium. These silos are 80 ft in diameter, 36 ft high to the center of the dome, and 26.75 ft to the top of the vertical side walls. The test facility contained two test systems, each designed for a specific purpose. The first system, the Integrated Test Loop (ITL), a near-full-scale plant including the actual equipment to be installed at the Fernald Site, was designed to demonstrate the sluicing operation and confirm the selection of a slurry pump, the optimal sluicing nozzle operation, and the preliminary design material balance. The second system, the Component Test Loop (CTL), was designed to evaluate many of the key individual components of the waste retrieval system over an extended run. The major results of the initial testing performed during July and August 2002 confirmed that the AWR approach to sluicing was feasible. The ITL testing confirmed the following: (1) The selected slurry pump (Hazleton 3-20 type SHW) performed well and is suitable for AWR application. However, the pump's motor should be upgraded to a 200-hp model and be driven by a 150-hp variable-frequency drive (VFD). A 200-hp VFD is not much more expensive and would allow the pump to operate at full speed. (2) The best nozzle performance was achieved by using 15/16-in. nozzles operated alternately. This configuration appeared to most effectively mine the surrogate. (3) The Solartron densitometer, which was tested as an alternative mass flow measurement device, did not operate effectively. Consequently, it is not suitable for application to the AWR process. (4) Initially, the spray ring (operated at approximately 2300 psi) and the nozzles provided by the pump vendor did not perform acceptably. The nozzles were replaced with a more robust model, and the performance was then acceptable. (5) The average solids concentration achieved in the slurry before Bentogrout addition was approximately 16% by weight. The solids concentration of the slurry after Bentogrout addition ranged from 26% to approximately 40%. The slurry pump and ITL system performed well at every concentration. No line plugging or other problems were noted. The results of the CTL runs and later ITL testing are summarized in an appendix to this report.

Abraham, TJ

2003-10-22

238

[Hyperspectral optimum wavelengths and Fisher discrimination analysis to distinguish different concentrations of aflatoxin on corn kernel surface].  

PubMed

Aflatoxin is a toxic metabolite widely existing in corn. In the present paper, the feasibility of detecting aflatoxin on corn kernel surface by hyperspectral imaging technology was verified. The corn called pioneer with the same shape is provided by Toxicology and Mycotoxin Research Unit. With methanol configuration, four different concentrations of aflatoxin solutions were prepared and dripped on every 30 corn kernels. Also other clean 30 kernels without aflatoxin dripped were prepared to be the control samples. Among the 150 kernel samples, 103 training samples and 47 validation samples were prepared randomly. Firstly, hyperspectral image in the range of 400 to 1 000 nm was collected. For eliminating the deviations in original spectrum, standard normal variate transformation (SNV) was adopted as pretreatment method. And then several optimum wavelengths were selected by the principle of minimum misdiagnosis rate. After that the selected optimum wavelengths were taken as the input of the Fisher discrimination analysis to discriminate the different concentrations of aflatoxin on the corn. Finally, the discrimination model based on four optimum wavelengths (812.42, 873.00, 900.36 and 965.00 nm) was built and the accuracy of the model was tested. Results indicate that the classification accuracy of calibration and validation set was 87.4% and 80.9% respectively. This method provides basis for designing the corresponding portable instrument and distinguishing aflatoxin produced by naturally metabolism in corn. PMID:25269286

Chu, Xuan; Wang, Wei; Zhang, Lu-Da; Guo, Lang-Hua; Feldner, Peggy; Heitschmidt, Gerald

2014-07-01

239

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

240

Designing optimum completely positive maps for quantum teleportation  

NASA Astrophysics Data System (ADS)

We study a general teleportation scheme with an arbitrary state of the pair of particles (2 and 3) shared by Alice and Bob, and arbitrary measurements on the input particle 1 and one of the members (2) of the pair on Alice's side. We find an efficient iterative algorithm for identifying optimum operations on Bob's side. In particular, we find that simple unitary transformations on his side are not always optimal even if particles 2 and 3 are perfectly entangled. We describe the most interesting protocols in the language of extremal completely positive maps.

?eh?ek, J.; Hradil, Z.; Fiurek, J.; Brukner, ?.

2001-12-01

241

Determination of optimum electrolyte composition for molten carbonate fuel cells  

SciTech Connect

The objective of this study is to determine the optimum electrolyte composition for molten carbonate fuel cells. To accomplish this, the contractor will provide: (1) Comprehensive reports of on-going efforts to optimize carbonate composition. (2) A list of characteristics affected by electrolyte composition variations (e.g. ionic conductivity, vapor pressure, melting range, gas solubility, exchange current densities on NiO, corrosion and cathode dissolution effects). (3) Assessment of the overall effects that these characteristics have on state-of-the-art cell voltage and lifetime.

Yuh, C.Y.; Pigeaud, A.

1987-01-01

242

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 âdownstreamâ 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

243

1. Dynamics of the Loop Current Experiment  

E-print Network

in Loop Current Eddies Ekman and Franklin Kathleen A. Donohue1, Robert Leben2 Goals: Increase dynamical understanding of Loop Current, eddy-shedding mechanisms periphery precede Loop Current Eddy formaYon. Upper-layer Loop Current flows

Rhode Island, University of

244

On Loops in Inflation  

E-print Network

We study loop corrections to correlation functions of inflationary perturbations. Previous calculations have found that the two-point function can have a logarithmic running of the form log(k/mu), where k is the wavenumber of the perturbation, and mu is the renormalization scale. We highlight that this result would have profound consequences for both eternal inflation and the predictivity of standard inflation. We find a different result. We consider two sets of theories: one where the inflaton has a large cubic self-interaction and one where the inflaton interacts gravitationally with N massless spectator scalar fields. We find that there is a logarithmic running but of the form log(H/mu), where H is the Hubble constant during inflation. We find this result in three independent ways: by performing the calculation with a sharp cutoff in frequency-momentum space, in dimensional regularization and by the simple procedure of making the loop integral dimensionless. For the simplest of our theories we explicitly renormalize the correlation function proving that the divergencies can be reabsorbed and that the correlation function for super-horizon modes does not depend on time (once the tadpole terms have been properly taken into account). We prove the time-independence of the super-horizon correlation function in several additional ways: by doing the calculation of the correlation function at finite time using both the regularizations and by developing a formalism which expresses loop corrections directly in terms of renormalized quantities at each time. We find this last formalism particularly helpful to develop intuition which we then use to generalize our results to higher loops and different interactions.

Leonardo Senatore; Matias Zaldarriaga

2009-12-14

245

Loop transverse colostomy  

Microsoft Academic Search

All large-bowel stomas (198) performed between 1970 and 1980 in a community hospital were reviewed. Twenty-nine stomas were\\u000a loop transverse colostomies. There were five deaths, a complication rate related to the stoma of 28 per cent, and only 18\\u000a patients ever achieved colostomy closure. Our conclusions are as follows: (1) transverse colostomy is a holdover from the\\u000a past; (2) temporary

Martin J. Winkler; Peter A. Volpe

1982-01-01

246

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

247

Verification of Loop Diagnostics  

NASA Technical Reports Server (NTRS)

Many different techniques have been used to characterize the plasma in the solar corona: density-sensitive spectral line ratios are used to infer the density, the evolution of coronal structures in different passbands is used to infer the temperature evolution, and the simultaneous intensities measured in multiple passbands are used to determine the emission measure. All these analysis techniques assume that the intensity of the structures can be isolated through background subtraction. In this paper, we use simulated observations from a 3D hydrodynamic simulation of a coronal active region to verify these diagnostics. The density and temperature from the simulation are used to generate images in several passbands and spectral lines. We identify loop structures in the simulated images and calculate the loop background. We then determine the density, temperature and emission measure distribution as a function of time from the observations and compare with the true temperature and density of the loop. We find that the overall characteristics of the temperature, density, and emission measure are recovered by the analysis methods, but the details of the true temperature and density are not. For instance, the emission measure curves calculated from the simulated observations are much broader than the true emission measure distribution, though the average temperature evolution is similar. These differences are due, in part, to inadequate background subtraction, but also indicate a limitation of the analysis methods.

Winebarger, A.; Lionello, R.; Mok, Y.; Linker, J.; Mikic, Z.

2014-01-01

248

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

249

Integrable Wilson loops  

NASA Astrophysics Data System (ADS)

The generalized quark-antiquark potential of supersymmetric Yang-Mills theory on calculates the potential between a pair of heavy charged particles separated by an arbitrary angle on and also an angle in flavor space. It can be calculated by a Wilson loop following a prescribed path and couplings, or after a conformal transformation, by a cusped Wilson loop in flat space, hence also generalizing the usual concept of the cusp anomalous dimension. In this is calculated by an infinite open string. I present here an open spin-chain model which calculates the spectrum of excitations of such open strings. In the dual gauge theory these are cusped Wilson loops with extra operator insertions at the cusp. The boundaries of the spin-chain introduce a non-trivial reflection phase and break the bulk symmetry down to a single copy of . The dependence on the two angles is captured by the two embeddings of this algebra into , i.e., by a global rotation. The exact answer to this problem is conjectured to be given by solutions to a set of twisted boundary thermodynamic Bethe ansatz integral equations. In particular the generalized quark-antiquark potential or cusp anomalous dimension is recovered by calculating the ground state energy of the minimal length spin-chain, with no sites. It gets contributions only from virtual particles reflecting off the boundaries. I reproduce from this calculation some known weak coupling perturtbative results.

Drukker, Nadav

2013-10-01

250

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

251

Carbon sequestration, optimum forest rotation and their environmental impact  

SciTech Connect

Due to their large biomass forests assume an important role in the global carbon cycle by moderating the greenhouse effect of atmospheric pollution. The Kyoto Protocol recognises this contribution by allocating carbon credits to countries which are able to create new forest areas. Sequestrated carbon provides an environmental benefit thus must be taken into account in cost-benefit analysis of afforestation projects. Furthermore, like timber output carbon credits are now tradable assets in the carbon exchange. By using British data, this paper looks at the issue of identifying optimum felling age by considering carbon sequestration benefits simultaneously with timber yields. The results of this analysis show that the inclusion of carbon benefits prolongs the optimum cutting age by requiring trees to stand longer in order to soak up more CO{sub 2}. Consequently this finding must be considered in any carbon accounting calculations. - Highlights: Black-Right-Pointing-Pointer Carbon sequestration in forestry is an environmental benefit. Black-Right-Pointing-Pointer It moderates the problem of global warming. Black-Right-Pointing-Pointer It prolongs the gestation period in harvesting. Black-Right-Pointing-Pointer This paper uses British data in less favoured districts for growing Sitka spruce species.

Kula, Erhun, E-mail: erhun.kula@bahcesehir.edu.tr [Department of Economics, Bahcesehir University, Besiktas, Istanbul (Turkey); Gunalay, Yavuz, E-mail: yavuz.gunalay@bahcesehir.edu.tr [Department of Business Studies, Bahcesehir University, Besiktas, Istanbul (Turkey)

2012-11-15

252

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

253

Optimum usage of prilocaine-lidocaine cream in premature ejaculation.  

PubMed

Premature ejaculation is a common male sexual disorder in which orgasm and ejaculation occur before the desired moment. The primary therapeutic approach to premature ejaculation has been behavioural and pharmacotherapy. In this study, we evaluated the efficacy and optimum usage of lidocaine-prilocaine cream 5% in preventing premature ejaculation. Forty patients were examined in the study group and randomized into four groups, each comprising 10 patients. Patients in group 1 applied lidocaine-prilocaine cream 5% for 20 min, the patients in group 2 applied it for 30 min, and the patients in group 3 applied the cream for 45 min before sexual contact, with all patients covering the penis with a condom. Patients in the fourth group applied a base cream as placebo. In group 1, the pre-ejaculation period increased to 6.71 +/- 2.54 min without any adverse effects. In group 2, although the pre-ejaculation period increased in four patients up to 8.70 +/- 1.70 min, six patients in this group and all patients in group 3 had erection loss because of numbness. In the placebo group, there was no change in their pre-ejaculation period. Therefore, lidocaine-prilocaine cream 5% is effective in premature ejaculation and 20 min of application time before sexual contact is the optimum period. PMID:12472618

Atikeler, M K; Gecit, I; Senol, F A

2002-12-01

254

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

255

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

256

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

257

Plasticity of 150-Loop in Influenza Neuraminidase Explored by Hamiltonian Replica Exchange Molecular Dynamics Simulations  

PubMed Central

Neuraminidase (NA) of influenza is a key target for antiviral inhibitors, and the 150-cavity in group-1 NA provides new insight in treating this disease. However, NA of 2009 pandemic influenza (09N1) was found lacking this cavity in a crystal structure. To address the issue of flexibility of the 150-loop, Hamiltonian replica exchange molecular dynamics simulations were performed on different groups of NAs. Free energy landscape calculated based on the volume of 150-cavity indicates that 09N1 prefers open forms of 150-loop. The turn A (residues 147150) of the 150-loop is discovered as the most dynamical motif which induces the inter-conversion of this loop among different conformations. In the turn A, the backbone dynamic of residue 149 is highly related with the shape of 150-loop, thus can function as a marker for the conformation of 150-loop. As a contrast, the closed conformation of 150-loop is more energetically favorable in N2, one of group-2 NAs. The D147-H150 salt bridge is found having no correlation with the conformation of 150-loop. Instead the intimate salt bridge interaction between the 150 and 430 loops in N2 variant contributes the stabilizing factor for the closed form of 150-loop. The clustering analysis elaborates the structural plasticity of the loop. This enhanced sampling simulation provides more information in further structural-based drug discovery on influenza virus. PMID:23593372

Han, Nanyu; Mu, Yuguang

2013-01-01

258

Shapes and Shaping of Planetary Nebulae  

Microsoft Academic Search

We review the state of observational and theoretical studies of the shaping of planetary nebulae (PNe) and protoplanetary nebulae (pPNe). In the past decade, high-resolution studies of PNe have revealed a bewildering array of morphologies with elaborate symmetries. Recent imaging studies of pPNe exhibit an even richer array of shapes. The variety of shapes, sometimes multiaxial symmetries, carefully arranged systems

Bruce Balick; Adam Frank

2002-01-01

259

Development of a fuel-powered compact SMA (Shape Memory Alloy) actuator system  

E-print Network

frequencies of smart materials [12]. .................9 Figure 7. Hysteresis loop in shape memory alloy. ...........................................................12 Figure 8. Brass connector for SMA actuator.../heat exchanger.....................................................128 Figure 91. Micro-tube heat exchanger. ..........................................................................129 Figure 92. Brass gear pump...

Jun, Hyoung Yoll

2005-02-17

260

Closed-loop and strangulating intestinal obstruction: CT signs.  

PubMed

In 19 patients with closed-loop intestinal obstruction, including 16 patients with strangulating obstruction, the findings at examination with computed tomography (CT) were retrospectively correlated with the surgical and pathologic findings and evaluated by two radiologists. Signs of closed-loop obstruction, present in 15 patients, were associated with the configuration of the incarcerated loop of small bowel, abnormalities detected at the site of obstruction, or both. These abnormalities were the following: a U-shaped, distended, fluid-filled bowel loop; the whirl sign; the beak sign; a triangular loop; two adjacent collapsed loops of bowel at the site of obstruction; or all of these. CT signs of strangulation, seen in 10 of the 16 patients with ischemic or infarcted bowel, were associated with the appearance of the bowel wall (thickening, high attenuation, and the target sign), abnormalities in the attached mesentery, or both. In mechanical obstruction of the small bowel, detection of ischemic changes in the bowel wall or mesentery with CT indicates strangulation. Absence of CT findings of ischemia or infarction does not rule out strangulation. PMID:1438761

Balthazar, E J; Birnbaum, B A; Megibow, A J; Gordon, R B; Whelan, C A; Hulnick, D H

1992-12-01

261

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

262

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

263

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

264

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

265

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

266

Constraint-Based Local Search for Constrained Optimum Paths Problems  

NASA Astrophysics Data System (ADS)

Constrained Optimum Path (COP) problems arise in many real-life applications and are ubiquitous in communication networks. They have been traditionally approached by dedicated algorithms, which are often hard to extend with side constraints and to apply widely. This paper proposes a constraint-based local search (CBLS) framework for COP applications, bringing the compositionality, reuse, and extensibility at the core of CBLS and CP systems. The modeling contribution is the ability to express compositional models for various COP applications at a high level of abstraction, while cleanly separating the model and the search procedure. The main technical contribution is a connected neighborhood based on rooted spanning trees to find high-quality solutions to COP problems. The framework, implemented in COMET, is applied to Resource Constrained Shortest Path (RCSP) problems (with and without side constraints) and to the edge-disjoint paths problem (EDP). Computational results show the potential significance of the approach.

Pham, Quang Dung; Deville, Yves; van Hentenryck, Pascal

267

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

268

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

269

Self-Similar Evaporation of a Rigidly-Rotating Cosmic String Loop  

E-print Network

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.

Malcolm Anderson

2005-05-31

270

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

271

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

272

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

273

The double loop mattress suture.  

PubMed

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

274

Optimum Absorber Parameters for Tuned Liquid Column Dampers  

Microsoft Academic Search

Tuned liquid column dampers (TLCDs) are a class of tuned liquid dampers that impart indirect damping to the primary structure through oscillations of the liquid column in a U-shaped container. The energy dissipation in the water column results from the passage of the liquid through an orifice with inherent head-loss characteristics. The overall damping in a TLCD depends on the

Swaroop K. Yalla; Ahsan Kareem

2000-01-01

275

Optimum Aerodynamic Design Using CFD and Control Theory  

E-print Network

, with control by the boundary as a free surface. The Frechet derivative of the cost function is determined via problem as a search for the shape that will generate the desired pressure distribution. This approach recognizes that the designer usually has an idea of the the kind of pressure distribution that will lead

Jameson, Antony

276

Structural Optimization of Non-Nucleotide Loop Replacements for Duplex and Triplex DNAs  

PubMed Central

Described are studies systematically exploring structural effects in he use of ethylene glycol (EG) oligomers as non-nucleotide replacements for nucleotide loops in duplex and triplex DNAs. The new structurally optimized loop replacements are more stabilizing in duplexes and triplexes than previously described EG-based linkers. A series of compounds ranging in length from tris(ethylene glycol) to octakis(ethylene glycol) are derivatized as monodimethoxytrityl ethers on one end and phosphoramidites on the other, to enable their incorporation into DNA strands by automated methods. These linker molecules span lengths ranging from 13 to 31 in extended conformation. They are incorporated into a series of duplex-forming and triplex-forming sequences, and the stabilities of the corresponding helixes are measured by thermal denaturation. In the duplex series, results show that the optimum linker is the one derived from heptakis(ethylene glycol), which is longer than most previous loop replacements studied. This affords a helix with greater thermal stability than one with a natural T4 loop. In the triplex series, the loop replacements were examined in four separate situations, in which the loop lies in the 5? or 3? orientation and the central purine target strand is short or extends beyond the loop. Results show that in all cases the loop derived from octakis(ethylene glycol) (EG8) gives the greatest stability. In the cases where the target strand is short, the EG8-linked probe strands bind with affinities in some cases greater than those with a natural pentanucleotide (T5) loop. For the cases where the target strand extends beyond the linker, the EG8-linked strands are much lower in the 5? loop orientation than in the 3? loop orientation. It is found that extension by one additional nucleotide in one of the bonding domains in the EG-linked series can result in considerably greater stabilities with long target strands. Overall, the data show that optimum loop replacements are longer than would be expected from simple distance analysis. The results are discussed in relation to expected lengths and geometries for double and triple helixes. The findings will be usefull in the design of synthetically modified nucleic acids for use as diagnostic probes, as biochemical tools, and as potential therapeutic agents. PMID:20871801

Rumney, Squire; Kool, Eric T.

2009-01-01

277

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 24.23C and 23.50 to 25.97m, 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 25.70C and 23.50 to 29.44m, 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, 22.73C to 24.23C, and 23.5m to 26.0m, 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

278

On the optimum distance for signal-energy mapping in extensive air shower arrays  

E-print Network

In high energy cosmic rays surface arrays, the primary energy is currently determined from the value of the lateral distribution function (LDF) at a fixed optimum distance ropt from the shower core. The value of ropt is mainly related to the geometry of the array and is, therefore, considered as fixed independently of the shower energy or direction. Here, we demonstrate that the dependence of ropt on energy and zenith angle is not negligible. As a consequence, this method may not reconstruct properly the shape of the spectrum and might change the position of spectral features like the ankle. This result applies for pure surface array experiments but not to hybrid experiments, like the Pierre Auger Observatory, where hybrid events are used to calibrate the reconstructed energy of surface events. Additionally, events with saturated stations must be either properly corrected or eliminated altogether from the analysis when applying the ropt method. We show that calculating a specific ropt on a shower-to-shower ba...

Ros, G; Del Peral, L; D'Olivo, J C; Arqueros, F; Rodriguez-Frias, M D

2009-01-01

279

Loop-the-Loop: Bringing Theory into Practice  

ERIC Educational Resources Information Center

During the Thai high-school physics teacher training programme, we used an aluminum loop-the-loop system built by the Institute for the Promotion of Teaching Science and Technology (IPST) to demonstrate a circular motion and investigate the concept of the conservation of mechanical energy. There were 27 high-school teachers from three provinces,

Suwonjandee, N.; Asavapibhop, B.

2012-01-01

280

Isolated roux loop pancreaticojejunostomy vs single loop pancreaticojejunostomy after pancreaticoduodenectomy  

Microsoft Academic Search

BackgroundPancreatic anastomotic leaks are a major cause of morbidity and mortality following pancreaticoduodenectomy, and no single technique of reconstruction has shown to be superior. The aimof this study was to review the experience of single loop versus isolated Roux loop pancreaticojejunostomy in a series of patients undergoing pancreatic head resection.

Lileswar Kaman; Sudip Sanyal; Arunanshu Behera; Rajinder Singh; Rabindra Nath Katariya

2008-01-01

281

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

282

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.

2012-09-06

283

Pulse thermal loop  

NASA Technical Reports Server (NTRS)

A pulse thermal loop heat transfer system includes a means to use pressure rises in a pair of evaporators to circulate a heat transfer fluid. The system includes one or more valves that iteratively, alternately couple the outlets the evaporators to the condenser. While flow proceeds from one of the evaporators to the condenser, heating creates a pressure rise in the other evaporator, which has its outlet blocked to prevent fluid from exiting the other evaporator. When the flow path is reconfigured to allow flow from the other evaporator to the condenser, the pressure in the other evaporator is used to circulate a pulse of fluid through the system. The reconfiguring of the flow path, by actuating or otherwise changing the configuration of the one or more valves, may be triggered when a predetermined pressure difference between the evaporators is reached.

Weislogel, Mark M. (Inventor)

2002-01-01

284

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 Zrich, Zrich (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

285

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

286

Dynamic PID loop control  

E-print Network

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; Theilacker, J; Soyars, W; Martinez, A; Bossert, R; DeGraff, B; Darve, C

2012-01-01

287

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.

288

Polarization beam shaping.  

PubMed

Spatial engineering of polarization is proposed as a novel method of beam shaping. It is shown that a flat-top-shaped focus can be obtained in the far field by changing the polarization in the pupil plane in a spatially inhomogeneous manner. Experiments have been carried out to verify the validity of this method in one dimension. By comparison with traditional beam shaping methods, polarization beam shaping yields the smallest flat-top focus while maintaining high efficiency. PMID:18026561

Hao, Bing; Leger, James

2007-11-20

289

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.

OMSI

2004-01-01

290

The Princeton Shape Benchmark  

Microsoft Academic Search

In recent years, many shape representations and geomet- ric algorithms have been proposed for matching 3D shapes. Usually, each algorithm is tested on a different (small) database of 3D models, and thus no direct comparison is available for competing methods. In this paper, we describe the Princeton Shape Bench- mark (PSB), a publicly available database of polygonal models collected from

Philip Shilane; Patrick Min; Michael M. Kazhdan; Thomas A. Funkhouser

2004-01-01

291

Shape Memory Polymer Research  

Microsoft Academic Search

The past several years have witnessed significant advances in the field of shape memory polymers (SMPs) with the elucidation of new compositions for property tuning, the discovery of new mechanisms for shape fixing and recovery, and the initiation of phenomenological modeling. We critically review research findings on new shape memory polymers along these lines, emphasizing exciting progress in the areas

Patrick T. Mather; Xiaofan Luo; Ingrid A. Rousseau

2009-01-01

292

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

293

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 Zat

1995-01-01

294

Holography from loop quantum gravity  

E-print Network

We show that holography arises naturally in the context of spherically symmetric loop quantum gravity. The result is not dependent on detailed assumptions about the dynamics of the theory being considered. It ties strongly the amount of information contained in a region of space to the tight mathematical underpinnings of loop quantum geometry, at least in this particular context.

Rodolfo Gambini; Jorge Pullin

2007-08-02

295

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

296

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

297

Optimum Conditions for Artificial Fruiting Body Formation of Cordyceps cardinalis  

PubMed Central

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

2010-01-01

298

Optimum bile acid treatment for rapid gall stone dissolution.  

PubMed Central

To determine the optimum bile acid regimen for rapid gall stone dissolution, 48 gall stone patients were divided into four groups of 12 according to stone diameter and were randomly allocated to receive one of four treatment regimens: bedtime or mealtime chenodeoxycholic acid (CDCA, 12 mg/kg/day) and bedtime or mealtime ursodeoxycholic acid (UDCA, 12 mg/kg/day). An additional 10 patients treated with a combination of CDCA plus UDCA (each 6 mg/kg/day) at bedtime were matched with the 10 patients on bedtime CDCA and the 10 on bedtime UDCA. The gall stone dissolution rates at six and 12 months were determined by standardised oral cholecystography and expressed as the percentage reduction in the gall stone volume after treatment. The gall stone dissolution rate at six months was higher for UDCA than CDCA treatment (median 78% v 48%, p less than 0.01), and for bedtime than mealtime administration (69% v 39%, p less than 0.02). Both differences were greater for stones less than 8 mm diameter. The dissolution rate was faster for combination therapy than for CDCA alone at both six (82% v 36%, p less than 0.05) and 12 months (100% v 54%, p less than 0.05), but was not different from UDCA alone. We conclude that bile acid treatment should be confined to patients with small gall stones and that bedtime administration of combined UDCA and CDCA is likely to provide the most effective and safe combination. PMID:1568660

Jazrawi, R P; Pigozzi, M G; Galatola, G; Lanzini, A; Northfield, T C

1992-01-01

299

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

300

Optimum frequency for subsurface-imaging synthetic-aperture radar  

SciTech Connect

A subsurface-imaging synthetic-aperture radar (SISAR) has potential for application in areas as diverse as non-proliferation programs for nuclear weapons to environmental monitoring. However, most conventional synthetic-aperture radars operate at higher microwave frequencies which do not significantly penetrate below the soil surface. This study attempts to provide a basis for determining optimum frequencies and frequency ranges which will allow synthetic-aperture imaging of buried targets. Since the radar return from a buried object must compete with the return from surface clutter, the signal-to-clutter ratio is an appropriate measure of performance for a SISAR. A parameter-based modeling approach is used to model the complex dielectric constant of the soil from measured data obtained from the literature. Theoretical random-surface scattering models, based on statistical solutions to Maxwell`s equations, are used to model the clutter. These models are combined to estimate the signal-to-clutter ratio for canonical targets buried in several soil configurations. Initial results indicate that the HF spectrum (3--30 MHz), although it could be used to detect certain targets under some conditions, has limited practical value for use with SISAR, while the upper vhf through uhf spectrum ({approximately}100 MHz--1 GHz) shows the most promise for a general purpose SISAR system. Recommendations are included for additional research.

Brock, B.C.; Patitz, W.E.

1993-05-01

301

Optimum frequency for subsurface-imaging synthetic-aperture radar  

SciTech Connect

A subsurface-imaging synthetic-aperture radar (SISAR) has potential for application in areas as diverse as non-proliferation programs for nuclear weapons to environmental monitoring. However, most conventional synthetic-aperture radars operate at higher microwave frequencies which do not significantly penetrate below the soil surface. This study attempts to provide a basis for determining optimum frequencies and frequency ranges which will allow synthetic-aperture imaging of buried targets. Since the radar return from a buried object must compete with the return from surface clutter, the signal-to-clutter ratio is an appropriate measure of performance for a SISAR. A parameter-based modeling approach is used to model the complex dielectric constant of the soil from measured data obtained from the literature. Theoretical random-surface scattering models, based on statistical solutions to Maxwell's equations, are used to model the clutter. These models are combined to estimate the signal-to-clutter ratio for canonical targets buried in several soil configurations. Initial results indicate that the HF spectrum (3--30 MHz), although it could be used to detect certain targets under some conditions, has limited practical value for use with SISAR, while the upper vhf through uhf spectrum ([approximately]100 MHz--1 GHz) shows the most promise for a general purpose SISAR system. Recommendations are included for additional research.

Brock, B.C.; Patitz, W.E.

1993-05-01

302

Conventional electromagnetic acoustic transducer development for optimum Lamb wave modes.  

PubMed

Lamb waves are normally utilized for inspecting thin metal sheets. Wheel type probes using piezoelectric oscillators have generally been used as the sensors for Lamb waves. Recently, the electromagnetic acoustic transducer (EMAT) has been developed and is beginning to be used as a Lamb wave detector. We have developed a useful type of transducer for Lamb waves. The new EMAT consists of a meander coil with a narrow distance of 2.5 mm and has a symmetrical structure in the vertical direction for both surface sides. The new EMAT can generate Lamb waves with variable wavelengths corresponding to the frequency range from approximately 300 kHz to 2.5 MHz and multiple modes, and can also generate selected symmetrical and anti-symmetrical mode Lamb waves. It is demonstrated that the optimum Lamb wave mode could be produced by the appropriate positioning of the EMATs and controlling the phase (same or inversed) of the electrical signal driving the device. The described EMAT can be used to examine steel (or other material) sheets of different thickness. It is also shown that the S0 (0.3 MHz) mode Lamb wave is the most effective for the deepest (up to 6 mm) penetration. PMID:12159989

Murayama, Riichi; Mizutani, Koichi

2002-05-01

303

Optimum Parameters for Freeze-Drying Decellularized Arterial Scaffolds  

PubMed Central

Decellularized arterial scaffolds have achieved success in advancing toward clinical use as vascular grafts. However, concerns remain regarding long-term preservation and sterilization of these scaffolds. Freeze drying offers a means of overcoming these concerns. In this study, we investigated the effects of various freeze-drying protocols on decellularized porcine carotid arteries and consequently, determined the optimum parameters to fabricate a stable, preserved scaffold with unaltered mechanical properties. Freeze drying by constant slow cooling to two final temperatures ((Tf), ?10C and ?40C) versus instant freezing was investigated by histological examination and mechanical testing. Slow cooling to Tf= ?10C produced a stiffer and less distensible response than the non freeze-dried scaffolds and resulted in disruption to the collagen fibers. The mechanical response of Tf= ?40C scaffolds demonstrated disruption to the elastin network, which was confirmed with histology. Snap freezing scaffolds in liquid nitrogen and freeze drying to Tf= ?40C with a precooled shelf at ?60C produced scaffolds with unaltered mechanical properties and a histology resembling non-freeze-dried scaffolds. The results of this study demonstrate the importance of optimizing the nucleation and ice crystal growth/size to ensure homogenous drying, preventing extracellular matrix disruption and subsequent inferior mechanical properties. This new manufacturing protocol creates the means for the preservation and sterilization of decellularized arterial scaffolds while simultaneously maintaining the mechanical properties of the tissue. PMID:23614758

Sheridan, William S.; Duffy, Garry P.

2013-01-01

304

Loop-bed combustion apparatus  

DOEpatents

The present invention is directed to a combustion apparatus in the configuration of a oblong annulus defining a closed loop. Particulate coal together with a sulfur sorbent such as sulfur or dolomite is introduced into the closed loop, ignited, and propelled at a high rate of speed around the loop. Flue gas is withdrawn from a location in the closed loop in close proximity to an area in the loop where centrifugal force imposed upon the larger particulate material maintains these particulates at a location spaced from the flue gas outlet. Only flue gas and smaller particulates resulting from the combustion and innerparticle grinding are discharged from the combustor. This structural arrangement provides increased combustion efficiency due to the essentially complete combustion of the coal particulates as well as increased sulfur absorption due to the innerparticle grinding of the sorbent which provides greater particle surface area.

Shang, Jer-Yu (Fairfax, VA); Mei, Joseph S. (Morgantown, WV); Slagle, Frank D. (Kingwood, WV); Notestein, John E. (Morgantown, WV)

1984-01-01

305

Jordan Loops Using Prover9/Mace4 to understand Jordan Loops  

E-print Network

Jordan Loops Using Prover9/Mace4 to understand Jordan Loops Kyle Pula June 22nd, 2007 Kyle Pula Using Prover9/Mace4 to understand Jordan Loops #12;Jordan Loops Jordan Loops A loop is a set with binary) and x · e = e · x = x A Jordan loop is a commutative loop satisfying x2 y · x = x2 · yx (1) Kyle Pula

Veroff, Robert

306

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

307

Numerical simulation of mold shapes 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

308

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

309

Helicoids, wrinkles, and loops in twisted ribbons.  

PubMed

We investigate the instabilities of a flat elastic ribbon subject to twist under tension and develop an integrated phase diagram of the observed shapes and transitions. We find that the primary buckling mode switches from being localized longitudinally along the length of the ribbon to transverse above a triple point characterized by a crossover tension that scales with ribbon elasticity and aspect ratio. Far from threshold, the longitudinally buckled ribbon evolves continuously into a self-creased helicoid with focusing of the curvature along the triangular edges. Further twist causes an anomalous transition to loops compared with rods due to the self-rigidity induced by the creases. When the ribbon is twisted under high tension, transverse wrinkles are observed due to the development of compressive stresses with higher harmonics for greater width-to-length ratios. Our results can be used to develop functional structures using a wide range of elastic materials and length scales. PMID:24206494

Chopin, Julien; Kudrolli, Arshad

2013-10-25

310

MHD phenomena with AC loop voltages in RFP plasmas  

NASA Astrophysics Data System (ADS)

The plasma's MHD response is an important aspect of experiments with applied AC loop voltages. For example, when oscillating-field current drive (OFCD), a type of helicity injection entailing phased AC poloidal and toroidal loop voltages, is applied to RFPs in the MST device with an empirically optimum phase of ?/8 between the two voltages, there is a decrease in magnetic-fluctuation amplitudes. By contrast, for ?/2, which is the phase of maximum helicity injection, additional bursts of magnetic fluctuations are induced, which internal measurements suggest are a linear MHD tearing response to the applied fields. Meanwhile, the AC loop voltages can entrain the normally quasiperiodic background sawtooth cycle in the RFP, triggering these discrete relaxation events to occur only at characteristic times within the OFCD cycle. This effect may involve criteria on the core safety factor and is investigated by equilibrium reconstructions of experiments in which AC fields of different frequencies and amplitudes are applied with a new programmable power supply. Finally, using internal probes, we plan to study the radial penetration of broadband AC fields from the switching of the solid-state programmable supply for possible effects on relaxation and current-profile control.

McCollam, K. J.; Almagri, A. F.; Holly, D. J.; Sarff, J. S.; Stone, D. R.; Triana, J. C.

2011-11-01

311

General shape optimization capability  

NASA Technical Reports Server (NTRS)

A method is described for calculating shape sensitivities, within MSC/NASTRAN, in a simple manner without resort to external programs. The method uses natural design variables to define the shape changes in a given structure. Once the shape sensitivities are obtained, the shape optimization process is carried out in a manner similar to property optimization processes. The capability of this method is illustrated by two examples: the shape optimization of a cantilever beam with holes, loaded by a point load at the free end (with the shape of the holes and the thickness of the beam selected as the design variables), and the shape optimization of a connecting rod subjected to several different loading and boundary conditions.

Chargin, Mladen K.; Raasch, Ingo; Bruns, Rudolf; Deuermeyer, Dawson

1991-01-01

312

Towards Analytic (g - 2)? at Four Loops  

NASA Astrophysics Data System (ADS)

In this contribution we present recent four-loop results for the muon anomalous magnetic moment based on analytic methods. In particular, fermionic corrections involving two or more closed electron loops or at least one tau lepton loop are discussed.

Steinhauser, Matthias

2014-12-01

313

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

314

Jet Shapes and Jet Algorithms in SCET  

E-print Network

Jet shapes are weighted sums over the four-momenta of the constituents of a jet and reveal details of its internal structure, potentially allowing discrimination of its partonic origin. In this work we make predictions for quark and gluon jet shape distributions in N-jet final states in e+e- collisions, defined with a cone or recombination algorithm, where we measure some jet shape observable on a subset of these jets. Using the framework of Soft-Collinear Effective Theory, we prove a factorization theorem for jet shape distributions and demonstrate the consistent renormalization-group running of the functions in the factorization theorem for any number of measured and unmeasured jets, any number of quark and gluon jets, and any angular size R of the jets, as long as R is much smaller than the angular separation between jets. We calculate the jet and soft functions for angularity jet shapes \\tau_a to one-loop order (O(alpha_s)) and resum a subset of the large logarithms of \\tau_a needed for next-to-leading logarithmic (NLL) accuracy for both cone and kT-type jets. We compare our predictions for the resummed \\tau_a distribution of a quark or a gluon jet produced in a 3-jet final state in e+e- annihilation to the output of a Monte Carlo event generator and find that the dependence on a and R is very similar.

Stephen D. Ellis; Andrew Hornig; Christopher Lee; Christopher K. Vermilion; Jonathan R. Walsh

2010-11-15

315

Experimental validation of optimum input polarization states for Mueller matrix determination with a dual photoelastic modulator polarimeter.  

PubMed

Dual photoelastic modulator polarimeters can measure light polarization, which is often described as a Stokes vector. By evaluating changes in polarization when light interacts with a sample, the sample Mueller matrix also can be derived, completely describing its interaction with polarized light. The choice of which and how many input Stokes vectors to use for sample investigation is under the experimenter's control. Previous work has predicted that sets of input Stokes vectors forming the vertices of platonic solids on the Poincar sphere allow for the most robust Mueller matrix determination. Further, when errors specific to the dual photoelastic modulator polarimeter are considered, simulations revealed that one specific shape and orientation of Stokes vectors (cube on the Poincar sphere with vertices away from principal sphere axes) allows for the most robust Mueller matrix determination. Here we experimentally validate the optimum input Stokes vectors for dual photoelastic modulator Mueller polarimetry, toward developing a robust polarimetric platform of increasing relevance to biophotonics. PMID:24322235

Gribble, Adam; Layden, David; Vitkin, I Alex

2013-12-15

316

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

317

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, Emlio C. N.

2006-03-01

318

Optimum Anthropometric Criteria for Ideal Body Composition Related Fitness  

PubMed Central

Objectives The three aims of this study were to establish equations for ideal body composition related fitness to be used by adults willing to gain optimum body composition related fitness; to predict the possible symmetrical major muscle circumference, and to compute the ideal body fat percentage (BFP) with ideal body weight (IBW) based on the body mass index (BMI). Methods Twenty-four athletes were intentionally selected, with heights of 166190 cm and aged 2042 years, according to a judging committee that used modified International Fitness Federation criteria for the Mr. Fitness competition super body category. Common anthropometric and body composition measurements were taken for the following independent variables: body height, upper limb length, lower limb length, thigh length, arm length, shoulder width, forearm length, shank length, and wrist girth; and for the following dependent variables: circumferences of shoulder, thigh, waist, hip, chest, biceps, forearm, shank, and neck. Skin fold thickness was measured at three sites by a Harpenden caliper to calculate BFP. Results The findings indicate that there was a predictive correlation between major independent variables and body circumferences. The mean range used to find out the ideal BFP percentage which was 5.66.7 %. The BMI equation used to find the IBW was H2 23.77 2 SE. Stepwise multiple regressions were also used to derive predictive equations. The most predictive independent variables were wrist girth and height. Conclusion It is suggested that the above equations, the ideal BFP percentage and the IBW be used as criteria in training sessions to achieve ideal body composition related fitness. PMID:21509084

Kilani, Hashem; Abu-Eisheh, Asem

2010-01-01

319

Coronal loop seismology using multiple transverse loop oscillation harmonics  

NASA Astrophysics Data System (ADS)

TRACE observations (23/11/1998 06:35:57-06:48:43UT) in the 171 bandpass of an active region are studied. Coronal loop oscillations are observed after a violent disruption of the equilibrium. The oscillation properties are studied to give seismological estimates of physical quantities, such as the density scale height. A loop segment is traced during the oscillation, and the resulting time series is analysed for periodicities. In the loop segment displacement, two periods are found: 435.64.5 s and 242.76.4 s, consistent with the periods of the fundamental and 2nd harmonic fast kink oscillation. The small uncertainties allow us to estimate the density scale height in the loop to be 109 Mm, which is about double the estimated hydrostatical value of 50 Mm. The eigenfunction is used to do spatial coronal seismology, but that method does not give any conclusive results.

Van Doorsselaere, T.; Nakariakov, V. M.; Verwichte, E.

2008-05-01

320

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

321

Loop-deformed Poincar algebra  

NASA Astrophysics Data System (ADS)

In this letter we present evidence suggesting that loop quantum gravity leads to deformation of the local Poincar 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 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.

Mielczarek, Jakub

2014-11-01

322

Loop-deformed Poincar 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

323

Formation of current sheets and sigmoidal structure by the kink instability of a magnetic loop  

E-print Network

We study dynamical consequences of the kink instability of a twisted coronal flux rope, using the force-free coronal loop model by Titov & D\\'emoulin (1999) as the initial condition in ideal-MHD simulations. When a critical value of the twist is exceeded, the long-wavelength ($m=1$) kink mode develops. Analogous to the well-known cylindrical approximation, a helical current sheet is then formed at the interface with the surrounding medium. In contrast to the cylindrical case, upward-kinking loops form a second, vertical current sheet below the loop apex at the position of the hyperbolic flux tube (generalized X line) in the model. The current density is steepened in both sheets and eventually exceeds the current density in the loop (although the kink perturbation starts to saturate in our simulations without leading to a global eruption). The projection of the field lines that pass through the vertical current sheet shows an S shape whose sense agrees with the typical sense of transient sigmoidal (forward or reverse S-shaped) structures that brighten in soft X rays prior to coronal eruptions. The upward-kinked loop has the opposite S shape, leading to the conclusion that such sigmoids do not generally show the erupting loops themselves but indicate the formation of the vertical current sheet below them that is the central element of the standard flare model.

B. Kliem; V. S. Titov; T. Toeroek

2003-11-09

324

Design, fabrication and delivery of an improved single Elastic Loop Mobility System (ELMS)  

NASA Technical Reports Server (NTRS)

Several significant design improvements have been incorporated into the second-generation full-scale ELMS unit. A major improved design accomplishment was the increase of the load carrying capacity of elastic loops without severe weight or stress penalties. Redesign of the loop form and size, plus selection of a more advanced titanium alloy, resulted in performance characteristics representing a marked improvement over the first-generation unit. Another important design improvement was the shaping of the loop's footprint into a favorable form for uniform pressure distribution. Other improvements are associated with a more efficient drive torque transmission from the internal drive drums to the elastic loop which are expected to reduce the internal losses of the drive system. The new ELMS unit will be capable of being integrated, on a modularized basis, with a multi-loop articulated ELMS test vehicle as the next logical step in the development of the mobility concept.

Trautwein, W.

1972-01-01

325

Loop Quantum Gravity Phenomenology: Linking Loops to Observational Physics  

E-print Network

Research during the last decade demonstrates that effects originating on the Planck scale are currently being tested in multiple observational contexts. In this review we discuss quantum gravity phenomenological models and their possible links to loop quantum gravity. Particle frameworks, including kinematic models, broken and deformed Poincar\\'e symmetry, non-commutative geometry, relative locality and generalized uncertainty principle, and field theory frameworks, including Lorentz violating operators in effective field theory and non-commutative field theory, are discussed. The arguments relating loop quantum gravity to models with modified dispersion relations are reviewed, as well as, arguments supporting the preservation of local Lorentz invariance. The phenomenology related to loop quantum cosmology is briefly reviewed, with a focus on possible effects that might be tested in the near future. As the discussion makes clear, there remains much interesting work to do in establishing the connection between the fundamental theory of loop quantum gravity and these specific phenomenological models, in determining observational consequences of the characteristic aspects of loop quantum gravity, and in further refining current observations. Open problems related to these developments are highlighted. characteristic aspects of loop quantum gravity, and in further refining current observations. Open problems related to these developments are highlighted.

Florian Girelli; Franz Hinterleitner; Seth A. Major

2012-10-04

326

Noncontact guide system for traveling elastic steel plates: vibration control performance for different guideway shapes  

NASA Astrophysics Data System (ADS)

We have developed a noncontact guide system for a high-speed traveling elastic steel plate in which electromagnetic forces are applied by actuators at the edges of the plate to control its position. Recently, we have been examining a noncontact guide system, in which one of the loops of a belt-shaped thin steel plate is supported by a pulley, and another loop is guided without contact using electromagnets. It was confirmed experimentally that the loop shape of the thin steel plate changes with increasing traveling speed when no control is carried out. In this study, a basic examination of the technique for forming a guideway using electromagnets, in which the change in the uncontrolled loop shape is considered, was carried out. By comparing the results for guideways with several different shapes, the effect of the guideway shape on the vibration suppression performance of the steel plate was discussed experimentally. As a result, it was confirmed that the vibration suppression performance of the steel plate can be improved by adjusting the shape of the noncontact guide system that uses electromagnets to conform with that of the loop of the uncontrolled steel plate.

Kumagai, Hiroaki; Oshinoya, Yasuo; Ishibashi, Kazuhisa; Kasuya, Hirakazu

2007-12-01

327

Shaped charge perforating device  

SciTech Connect

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 for transferring detonation waves to the shaped charge units and for retaining the shaped charge units within the mounting locations; and means for aligning the tubular carrier within the tubular housing member so as to align the shaped charge units with the spaced recesses along the housing member, the alignment means further comprising an elongated slot in the housing member; and biasing means affixed to the carrier member for engagement within the slot.

Ayers, D.B.

1986-04-22

328

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

329

Shape-Memory Polymers  

Microsoft Academic Search

Material scientists predict a prominent role in the future for self-repairing and intelligent materials. Throughout the last few years, this concept has found growing interest as a result of the rise of a new class of polymers. These so- called shape-memory polymers by far surpass well-known metallic shape- memory alloys in their shape-memory properties. As a consequence of the relatively

Andreas Lendlein; Steffen Kelch

2002-01-01

330

A Multi-band VCO PLL with the Continuously Maintained Optimum VCO  

E-print Network

.-H. Kwon, K.-C. Choi and W.-Y. Choi A new architecture for a multi-band VCO PLL is presented which can1 A Multi-band VCO PLL with the Continuously Maintained Optimum VCO Control Voltage Y.-S. Park, D continuously maintain the optimum VCO sub-band and the VCO control voltage even with severe supply voltage

Choi, Woo-Young

331

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

332

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.

333

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.

334

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

335

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

336

Experimental methods for measuring the optimum amount of dispersant for seven Sumitomo alumina powders  

Microsoft Academic Search

Seven Sumitomo alumina powders of different surface areas and particle size distributions were studied with a view to determining the optimum amount of dispersant (Darvan 821A) required to stabilise aqueous suspensions prepared from the powders. Three different techniques were used; sedimentation, particle sizing and acoustophoresis. Acoustophoresis proved to be the most accurate and quickest way of establishing the optimum amount.

M. Burke; R. Greenwood; K. Kendall

1998-01-01

337

Loop Electrosurgical Excision Procedure (LEEP)  

MedlinePLUS

... that acts like a scalpel (surgical knife). An electric current is passed through the loop, which cuts away ... A procedure in which an instrument works with electric current to destroy tissue. Local Anesthesia: The use of ...

338

Faraday Loop in Changing Field  

NSDL National Science Digital Library

The EJS Faraday Loop Changing Field Model shows the induced emf in a changing external magnetic field. You can control the frequency, magnitude and type of variation in the external field as you would in the laboratory when using a function generator to produce current in a large coil. You can also change the size and orientation of the conducting loop. If Ejs is installed, right-clicking within the plot and selecting Open Ejs Model from the pop-up menu item allows for editing of the model. The Faraday Loop Changing Field model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_em_FaradayLoopChangingField.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models.

Cox, Anne

2011-12-07

339

Loop Electrosurgical Excision Procedure (LEEP)  

MedlinePLUS

... that acts like a scalpel (surgical knife). An electric current is passed through the loop, which cuts ... A procedure in which an instrument works with electric current to destroy tissue. Local Anesthesia: The use ...

340

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

341

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

342

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

343

[Optimum soil water supply range of Malus pumila].  

PubMed

By means of the determination of net photosynthetic rate and transpiration rate of the leaves of seven-year field and two-year spotted Malus pumila (Goldspur) under different soil water contents and illumination and calculation of water use efficiency (WUE), the optimum soil water supply range of Malus pumila was determined. The results showed that because photosynthetic advantageous radiation (PAR) and soil water content (SWC) decided the value of photosynthetic rate and transpiration rate of Goldspur, thus they influenced the value of WUE. The response of WUE to illumination had relations with soil water. When SWC was 10% (50% of field capacity-FC) or so, the maximum of WUE was the highest value among all the soil water treatment and reached about 230 mumolCO2.g-1H2O. When the water supply was adequate (SWC > 15%), the maximum was only 160 mumolCO2.g-1H2O or so, the difference between each SWC level was not obvious and simulated curve fundamentally overlapped, although WUE decreased slowly after reached the maximum. The variation of WUE with SWC had relations with illumination. WUE was the highest while PAR was in the range of 500-1,000 mumol.m-2.s-1). Because the state of soil water decided the values of stomatic resistance (RS) and leaf water potential, RS and psi 1 also had influence on the changes of WUE. When RS and psi 1 were respectively 2.0 s.cm-1 and -3.0 MPa, WUE was the highest, but Pn was relatively low, which was not good to the normal growth and fruitage of trees. From the overall consideration of WUE, Pn and Tr, the scopes of RS and psi 1 were 2-6 s.cm-1 and -2.1 approximately -1.65 MPa, respectively, which not only guaranteed the normal photosynthesis of Goldspur, but also benefited the increase of WUE. The scope of the corresponding SWC was 11%-15%, which was equal to 55%-75% of FC and this scope could be used as theoretical index of field water supply for Goldspur. PMID:14733015

Wang, Keqin

2003-09-01

344

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

345

Dynamical behaviour in coronal loops  

NASA Technical Reports Server (NTRS)

Rapid variability has been found in two active region coronal loops observed by the X-ray Polychromator (XRP) and the Hard X-ray Imaging Spectrometer (HXIS) onboard the Solar Maximum Mission (SMM). There appear to be surprisingly few observations of the short-time scale behavior of hot loops, and the evidence presented herein lends support to the hypothesis that coronal heating may be impulsive and driven by flaring.

Haisch, Bernhard M.

1986-01-01

346

The Structure of Coronal Loops  

NASA Technical Reports Server (NTRS)

It is widely believed that the simple coronal loops observed by XUV imagers, such as EIT, TRACE, or XRT, actually have a complex internal structure consisting of many (perhaps hundreds) of unresolved, interwoven "strands". According to the nanoflare model, photospheric motions tangle the strands, causing them to reconnect and release the energy required to produce the observed loop plasma. Although the strands, themselves, are unresolved by present-generation imagers, there is compelling evidence for their existence and for the nanoflare model from analysis of loop intensities and temporal evolution. A problem with this scenario is that, although reconnection can eliminate some of the strand tangles, it cannot destroy helicity, which should eventually build up to observable scales. we consider, therefore, the injection and evolution of helicity by the nanoflare process and its implications for the observed structure of loops and the large-scale corona. we argue that helicity does survive and build up to observable levels, but on spatial and temporal scales larger than those of coronal loops. we discuss the implications of these results for coronal loops and the corona, in general .

Antiochos, Spiro K.

2009-01-01

347

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

348

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

349

Searching for optimum sulfurous water well sites using surface geophysical methods  

NASA Astrophysics Data System (ADS)

The 'Rio dello Solfo' is a narrow and impervious valley in Bagni di Lusnizza (north-eastern of Italy), known since Roman times, for its sulfurous springs. This study aims to delineate the major mineralized waters pathway in order to exploit the resource. The ultimate aim is to drill one or more wells (up to 200 m depth) and withdraw sulfurous water which has temperature and geochemical characteristics similar to those present in the deep reservoir (about 500 m depth). To help identify an optimum location for an abstraction well at the site, a range of near surface geophysical techniques have been applied. Frequency domain electromagnetic (FDEM) and electrical resistivity tomography (ERT) at high spatial resolution were used for a preliminary mapping of the shallow distribution of resistivity to identify the mineralized water saturation zones. ERT profiles at low resolution (10 m electrode spacing) were acquired to define the main lithological structures and to recognize potential fracture zones and faults through which the sulfurous water may rise. In addition, a Mise-a-la-Masse configuration was used in order to characterize the shape of the conductive body. The methods used showed a high and clear resistivity contrast due to the presence of the sulfurous waters. ERT allowed the definition of the geological structures and morphology of the basement and fracture zones. This permitted the localization of the major flow pathway from 160 m depth to the surface. The mineralized waters probably rise through an intersection of a fault with a contact of different geological formations, reach the near surface and then migrate into debris deposits, mixing with the calcium bicarbonate rich waters. Current work is now attempting to understand the connection of the deep aquifer to the mineralized springs disseminated in the near area, using an integrated geophysical, geochemical and geological study.

Gervasio, I.; Della Vedova, B.; Cassiani, G.; Binley, A.

2011-12-01

350

Shape and area computation of cooperative workspace of dual-arm robot  

Microsoft Academic Search

Dual arm robots are essential to dexterity and broaden greatly the types of activities the robot can achieve. Exact computation of the boundary shape and volume or area of dual arm robot workspace is very important for its optimum design and application. In the paper, a ground experimental system of a dual arm space robot in two-dimension was illustrated, and

Yi Cao; Ke Lu; Qiwu Xie; Xiujuan Li

2009-01-01

351

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

352

Shape memory polymer nanocomposites  

Microsoft Academic Search

The paper describes the fabrication and characterization of composites with a shape memory polymer matrix and SiC nanoparticulate reinforcements. Composites based on a SMP matrix are active materials capable of recovering relatively large mechanical strains due to the application of heat. The composites were synthesized from a commercial shape memory polymer resin system and particulate SiC with an average diameter

Ken Gall; Martin L. Dunn; Yiping Liu; Dudley Finch; Mark Lake; Naseem A. Munshi

2002-01-01

353

Shape Up America  

MedlinePLUS

... Need ideas on incorporating fun into your familys fitness program? Donate to SUA Please consider a donation to Shape Up America! Your tax-deductible contribution helps us develop new initiatives to address the problem of obesity in America. Shape Up Secrets Chef's Cookbook OAAA Weight Management

354

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

355

How College Shapes Lives  

E-print Network

of a Liberal Arts Education ­ Howard Gardner 64 Higher Education and the Opportunity Gap ­ Isabel Sawhill 68How 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

Rohs, Remo

356

Building Big: Shapes Lab  

NSDL National Science Digital Library

Shapes Lab, from the PBS Building Big Series, shows how the shape of a structure affects its strength. Rectangles, arches, and triangles are compared for their distribution of stress and response to forces applied by the visitor. The site also contains information about forces, loads, and building materials.

2007-04-06

357

Improved peak shape fitting in alpha spectra.  

PubMed

Peak overlap is a recurrent issue in alpha-particle spectrometry, not only in routine analyses but also in the high-resolution spectra from which reference values for alpha emission probabilities are derived. In this work, improved peak shape formulae are presented for the deconvolution of alpha-particle spectra. They have been implemented as fit functions in a spreadsheet application and optimum fit parameters were searched with built-in optimisation routines. Deconvolution results are shown for a few challenging spectra with high statistical precision. The algorithm outperforms the best available routines for high-resolution spectrometry, which may facilitate a more reliable determination of alpha emission probabilities in the future. It is also applicable to alpha spectra with inferior energy resolution. PMID:25497323

Pomm, S; Caro Marroyo, B

2015-02-01

358

Aerodynamic Shape Optimization Using Hybridized Differential Evolution  

NASA Technical Reports Server (NTRS)

An aerodynamic shape optimization method that uses an evolutionary algorithm known at Differential Evolution (DE) in conjunction with various hybridization strategies is described. DE is a simple and robust evolutionary strategy that has been proven effective in determining the global optimum for several difficult optimization problems. Various hybridization strategies for DE are explored, including the use of neural networks as well as traditional local search methods. A Navier-Stokes solver is used to evaluate the various intermediate designs and provide inputs to the hybrid DE optimizer. The method is implemented on distributed parallel computers so that new designs can be obtained within reasonable turnaround times. Results are presented for the inverse design of a turbine airfoil from a modern jet engine. (The final paper will include at least one other aerodynamic design application). The capability of the method to search large design spaces and obtain the optimal airfoils in an automatic fashion is demonstrated.

Madavan, Nateri K.

2003-01-01

359

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

360

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

361

Wedding ring shaped excitation coil  

DOEpatents

A high frequency inductively coupled electrodeless lamp includes an excitation coil with an effective electrical length which is less than one half wavelength of a driving frequency applied thereto, preferably much less. The driving frequency may be greater than 100 MHz and is preferably as high as 915 MHz. Preferably, the excitation coil is configured as a non-helical, semi-cylindrical conductive surface having less than one turn, in the general shape of a wedding ring. At high frequencies, the current in the coil forms two loops which are spaced apart and parallel to each other. Configured appropriately, the coil approximates a Helmholtz configuration. The lamp preferably utilizes an bulb encased in a reflective ceramic cup with a pre-formed aperture defined therethrough. The ceramic cup may include structural features to aid in alignment and/or a flanged face to aid in thermal management. The lamp head is preferably an integrated lamp head comprising a metal matrix composite surrounding an insulating ceramic with the excitation integrally formed on the ceramic. A novel solid-state oscillator preferably provides RF power to the lamp. The oscillator is a single active element device capable of providing over 70 watts of power at over 70% efficiency.

MacLennan, Donald A. (Gaithersburg, MD); Tsai, Peter (Olney, MD)

2001-01-01

362

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

363

Optimum Projection Angle for Attaining Maximum Distance in a Soccer Punt Kick  

PubMed Central

To produce the greatest horizontal distance in a punt kick the ball must be projected at an appropriate angle. Here, we investigated the optimum projection angle that maximises the distance attained in a punt kick by a soccer goalkeeper. Two male players performed many maximum-effort kicks using projection angles of between 10 and 90. The kicks were recorded by a video camera at 100 Hz and a 2 D biomechanical analysis was conducted to obtain measures of the projection velocity, projection angle, projection height, ball spin rate, and foot velocity at impact. The players optimum projection angle was calculated by substituting mathematical equations for the relationships between the projection variables into the equations for the aerodynamic flight of a soccer ball. The calculated optimum projection angles were in agreement with the players preferred projection angles (40 and 44). In projectile sports even a small dependence of projection velocity on projection angle is sufficient to produce a substantial shift in the optimum projection angle away from 45. In the punt kicks studied here, the optimum projection angle was close to 45 because the projection velocity of the ball remained almost constant across all projection angles. This result is in contrast to throwing and jumping for maximum distance, where the projection velocity the athlete is able to achieve decreases substantially with increasing projection angle and so the optimum projection angle is well below 45. Key points The optimum projection angle that maximizes the distance of a punt kick by a soccer goalkeeper is about 45. The optimum projection angle is close to 45 because the projection velocity of the ball is almost the same at all projection angles. This result is in contrast to throwing and jumping for maximum distance, where the optimum projection angle is well below 45 because the projection velocity the athlete is able to achieve decreases substantially with increasing projection angle. PMID:24149315

Linthorne, Nicholas P.; Patel, Dipesh S.

2011-01-01

364

The influence of feed/cattle price relationships on the optimum cattle feeding systems and on the optimum location of feeding in Texas  

E-print Network

widely used in all areas of Texas. This is a process in which cattle are 9 Operating capital requirement is the amount of money needed to purchase feed, cattle, medicine, variable labor services, and other variable expenses. 10 The amount of feed...THE INFLUENCE OF FEED/CATTLE PRICE RELATIONSHIPS ON THE OPTIMUM CATTLE FEEDING SYSTEMS AND ON THE OPTIMUM LOCATION OF FEEDING IN TEXAS A Thesis EDDY JOE W~ Submitted to the Graduate College of Texas A&M University in partial fulfillment...

Williams, Eddy Joe

1971-01-01

365

Loop coupled resonator optical waveguides.  

PubMed

We propose a novel coupled resonator optical waveguide (CROW) structure that is made up of a waveguide loop. We theoretically investigate the forbidden band and conduction band conditions in an infinite periodic lattice. We also discuss the reflection- and transmission- spectra, group delay in finite periodic structures. Light has a larger group delay at the band edge in a periodic structure. The flat band pass filter and flat-top group delay can be realized in a non-periodic structure. Scattering matrix method is used to calculate the effects of waveguide loss on the optical characteristics of these structures. We also introduce a tunable coupling loop waveguide to compensate for the fabrication variations since the coupling coefficient of the directional coupler in the loop waveguide is a critical factor in determining the characteristics of a loop CROW. The loop CROW structure is suitable for a wide range of applications such as band pass filters, high Q microcavity, and optical buffers and so on. PMID:25321995

Song, Junfeng; Luo, Lian-Wee; Luo, Xianshu; Zhou, Haifeng; Tu, Xiaoguang; Jia, Lianxi; Fang, Qing; Lo, Guo-Qiang

2014-10-01

366

The 21cm Signature of a Cosmic String Loop  

E-print Network

Cosmic string loops lead to nonlinear baryon overdensities at early times, even before the time which in the standard LCDM model corresponds to the time of reionization. These overdense structures lead to signals in 21cm redshift surveys at large redshifts. In this paper, we calculate the amplitude and shape of the string loop-induced 21cm brightness temperature. We find that a string loop leads to a roughly elliptical region in redshift space with extra 21cm emission. The excess brightness temperature for strings with a tension close to the current upper bound can be as high as 1 degree K for string loops generated at early cosmological times (times comparable to the time of equal matter and radiation) and observed at a redshift of z + 1 = 30. The angular extent of these predicted "bright spots" is of the order 0.1 degree for a value of the string tension equal to the current upper bound. These signals should be detectable in upcoming high redshift 21cm surveys.

Pagano, Michael

2012-01-01

367

The 21 cm signature of a cosmic string loop  

SciTech Connect

Cosmic string loops lead to nonlinear baryon overdensities at early times, even before the time which in the standard LCDM model corresponds to the time of reionization. These overdense structures lead to signals in 21 cm redshift surveys at large redshifts. In this paper, we calculate the amplitude and shape of the string loop-induced 21 cm brightness temperature. We find that a string loop leads to a roughly elliptical region in redshift space with extra 21 cm emission. The excess brightness temperature for strings with a tension close to the current upper bound can be as high as 1deg K for string loops generated at early cosmological times (times comparable to the time of equal matter and radiation) and observed at a redshift of z+1 = 30. The angular extent of these predicted 'bright spots' is x{sup '}. These signals should be detectable in upcoming high redshift 21 cm surveys. We also discuss the application of our results to global monopoles and primordial black holes.

Pagano, Michael; Brandenberger, Robert, E-mail: paganom@physics.mcgill.ca, E-mail: rhb@physics.mcgill.ca [Department of Physics, McGill University, 3600 Rue University, Montral, QC, H3A 2T8 (Canada)

2012-05-01

368

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

369

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

370

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

371

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

372

Duality beyond the first loop  

NASA Astrophysics Data System (ADS)

In this article we give a calculation of the two-loop ?-model corrections to the T-duality map in string theory. We use the effective action approach, and analyze two-loop corrections in a specific subtraction scheme. Focusing on backgrounds which have a single Abelian isometry, we find the explicit form for the O(?') modifications of the lowest order duality transformations. Rather surprisingly, the manifest two-loop duality depends crucially on the torsion field. In contrast with the dilaton and metric fields, which are merely passive spectators, the torsion plays a more active role, because of the anomalous couplings to the gauge fields that arise via dimensional reduction. Our results support the interpretation of T duality as an expansion in the inverse string tension ?', and its order-by-order realization as a manifest symmetry of the full string theory.

Kaloper, Nemanja; Meissner, Krzysztof A.

1997-12-01

373

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

374

Refrigerator with anti-sweat hot liquid loop  

SciTech Connect

A cabinet assembly for a refrigerator having a freezer compartment ontop with two top front corners, a fresh food compartment on the bottom, a mullion partition between the compartments and a hot liquid anti-sweat loop is described comprising; an outer sheet metal shell having a top panel, side panels and a front face, a brace located at each of the two top front corners of the cabinet and having two formed sections at right angles to each other and each section is formed as an inwardly open U-shaped channel having a base, a first leg and a second leg spaced apart and integrally joined to the base, fastening means for rigidly attaching each of the second leg of the corner braces to the flange of the third wall of the front face, and means to secure a portion of the hot liquid anti-sweat loop to the braces.

Woolley, S.J.; Cushing, D.S.; Jenkins, T.E.; Gerdes, K.W.; Sisler, R.R.

1988-04-05

375

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

376

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

377

Loop quantum geometry: a primer  

NASA Astrophysics Data System (ADS)

This is the written version of a lecture given at the ''VI Mexican School of Gravitation and Mathematical Physics'' (Nov 21-27, 2004, Playa del Carmen, Mxico), introducing the basics of Loop Quantum Geometry. The purpose of the written contribution is to provide a Primer version, that is, a first entry into Loop Quantum Gravity and to present at the same time a friendly guide to the existing pedagogical literature on the subject. This account is geared towards graduate students and non-experts interested in learning the basics of the subject.

Corichi, Alejandro

2005-01-01

378

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

379

Loop quantum cosmology: an overview  

NASA Astrophysics Data System (ADS)

A brief overview of loop quantum cosmology of homogeneous isotropic models is presented with emphasis on the origin of and subtleties associated with the resolution of big bang and big crunch singularities. These results bear out the remarkable intuition that John Wheeler had. Discussion is organized at two levels. The the main text provides a birds eye view of the subject that should be accessible to non-experts. Appendices address conceptual and technical issues that are often raised by experts in loop quantum gravity and string theory.

Ashtekar, Abhay

2009-04-01

380

Superresolution laser beam shaping.  

PubMed

The superresolution technique is well known for its ability to compress the central diffractive spot that is smaller than the Airy diffractive spot. In this paper, we extend the superresolution technique for different laser beam shaping. A complete set of superresolution diffractive elements is developed for the flat-top beam shaping, the single-circle beam shaping, and the novel circular Dammann grating. Five phase plates, corresponding to each of its applications, have been made by use of micro-optics technology. Experiments that are presented are in good agreement with the theoretical results. The superresolution technique presented in this paper should be highly interesting for the wide applications of laser beam shaping. PMID:15074420

Jia, Jia; Zhou, Changhe; Sun, Xiaohui; Liu, Liren

2004-04-01

381

WFU Physics Demo Video: Miller Loop-de-Loop  

NSDL National Science Digital Library

This video demonstrates conservation of energy. A ball is released at the higher end of the track. Since energy is conserved, the ball will roll around the loop and off the other, lower end. It is part of a collection of typical lecture demonstration videos put together by the physics department at Wake Forest University.

G. Eric Matthews, Professor

2008-06-23

382

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

383

Frequency Selective Reflectarray Using Crossed-Dipole Elements With Square Loops for Wireless Communication Applications  

Microsoft Academic Search

A new frequency selective reflectarray (FSR) com- prising a crossed-dipole array and a frequency selective surface (FSS) of square loops printed on both sides of a dielectric substrate is presented for wireless communication applications. The reflec- tarray functions as a reflector, and generates the desired reflected beam shape while steering the primary wave source in the desired direction. Moreover, the

Long Li; Qiang Chen; Qiaowei Yuan; Kunio Sawaya; Tamami Maruyama; Tatsuo Furuno; Shinji Uebayashi

2011-01-01

384

A software system for optimum design and trajectory planning of robots  

Microsoft Academic Search

This paper describes an interactive graphic robot-simulation system that has been developed to carry out optimum design and\\u000a to provide a robot-independent off-line motion-planning tool. The system includes model building, optimum design, trajectory\\u000a planning and graphic display, and is capable of detecting collisions. Emphasis is given to graphics facilities (translation,\\u000a scaling, removal of hidden lines, image animation, etc.). The system

H. Ding; D. S. Li; J. X. Chen; Y. L. Xiong

1989-01-01

385

Optimum linear combination strategy for an N-channel polarization-sensitive imaging or vision system  

Microsoft Academic Search

Received April 9, 1997; revised manuscript received September 8, 1997; accepted September 16, 1997 The optimum linear combination channels for an N-receptor polarization-sensitive imaging or vision system are found by using a principal-components analysis. The channels that are derived are optimum in the sense that their information contents are uncorrelated when considered over the ensemble of possible polarization signals. For

J. S. Tyo

1998-01-01

386

Methods of determining the optimum state of maturity for picking greenwrap tomatoes  

E-print Network

L IB R AR Y A&M COLLEGE OF TEXAS METHODS OF DETERMINING THE OPTIMUM STATE OF MATURITY FOR PICKING GREENWRAP TOMATOES A Dissertation By HAROLD BENJAMIN SORENSEN Submitted to the Graduate School of the Agricultural and Mechanical College... of Texas in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY May 1955 Major Subject: Horticulture ii METHODS OF DETERMINING THE OPTIMUM STATE OF MATURITT FOR PICKING GRSENWRAP TOMATOES A Dissertation By HAROLD BENJAMIN...

Sorensen, H. B.

1955-01-01

387

Optimum Binary to Symbol Coding for 6PSK and Bit Error Rate Performance  

Microsoft Academic Search

This paper proposes the optimum binary to symbol coding for 6PSK (senary PSK) that minimizes bit errors. 6PSK is expected to be able to transmit data at a higher information rate than QPSK with lower required Eb\\/N0 compared with 8PSK. In this paper, after discussing general principles of 6PSK, the authors propose the optimum 5 bit to 2 symbol coding

Seiichi NODA; S. Koike

2007-01-01

388

Optimum controller design for a multilevel AC-DC converter system  

Microsoft Academic Search

This paper focuses on the controller design based on symmetrical optimum and extended symmetrical optimum methods for a single-phase AC\\/DC converter system employing AC\\/AC direct converter and inverter with a medium frequency isolating transformer. Design criteria for the control system involve DC voltage control, reactive current control and AC current tracking. Simulation studies verify the designed controller performance for multi-level

Oguz Aydin; Alper Akdag; Philippe Stefanutti; Nicolas Hugo

2005-01-01

389

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

390

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

391

[MRO] Oligocrystalline Shape Memory Alloys  

E-print Network

Copper-based shape memory alloys (SMAs) exhibit excellent shape memory properties in single crystalline form. However, when they are polycrystalline, their shape memory properties are severely compromised by brittle fracture ...

Chen, Ying

392

Loop quantum gravity and observations  

E-print Network

Quantum gravity has long been thought to be completely decoupled from experiments or observations. Although it is true that smoking guns are still missing, there are now serious hopes that quantum gravity phenomena might be tested. We review here some possible ways to observe loop quantum gravity effects either in the framework of cosmology or in astroparticle physics.

A. Barrau; J. Grain

2014-10-07

393

The Origin of Postflare Loops  

Microsoft Academic Search

We apply a tracking technique, previously developed to study motions in the outer corona by Sheeley, Walters, Wang, and Howard, to 195 filtergrams obtained with the Transition Region and Coronal Explorer (TRACE) satellite and obtain height-time maps of the motions in the hot (10-20 MK) plasma clouds above postflare loop systems. These maps indicate the following two main characteristics.

N. R. Sheeley Jr.; H. P. Warren; Y.-M. Wang

2004-01-01

394

Closed Loop Knowledge System (CLKS)  

Microsoft Academic Search

This paper will provide information about the benefits of the closed loop knowledge system (CLKS). CLKS is based on a robust warehouse-based data repository and support tools where data access, storage and predictive data mining exploitation can be obtained from a web interface which will enable better decision support for war fighters. Knowledge engineering and analysis of the data required

S. Head

2008-01-01

395

OUTER LOOP LANDFILL CASE STUDY  

EPA Science Inventory

This presentation will describe the interim data reaulting from a CRADA between USEPA and Waste Management, Inc. at the outer Loop Landfill Bioreactor research project located in Louisville, KY. Recently updated data will be presented covering landfill solids, gas being collecte...

396

Three-loop contributions to hyperfine splitting: Muon loop light-by-light insertion and other closed lepton loops  

NASA Astrophysics Data System (ADS)

The muon and tauon light-by-light scattering contributions to hyperfine splitting in muonium are calculated. These results conclude the calculation of all hard three-loop contributions to hyperfine splitting generated by the graphs with closed fermion loops. We discuss the special role that the lepton anomalous magnetic moments play in these calculations. The full result for all three-loop radiative-recoil corrections to hyperfine splitting generated by the graphs with closed lepton loops is presented.

Eides, Michael I.; Shelyuto, Valery A.

2014-12-01

397

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

398

Impacting infant head shapes.  

PubMed

Infant sleep position impacts the development of head shape. Changes in infant sleep position, specifically the movement toward supine sleep, have led to a redefinition of normal head shape for infants in the United States. Historically, a dolichocephalic (elongated) head shape was the norm. Currently the norm has changed to a more brachycephalic (shorter and broader) shape. Since the American Academy of Pediatrics' Back to Sleep Campaign, the incidence of positional plagiocephaly has increased dramatically with a concurrent rise in the incidence of torticollis. Infants who require newborn intensive care, particularly premature infants, are more prone to positional plagiocephaly and dolichocephaly. Both can be prevented or minimized by proper positioning. The infant with an abnormal head shape requires careful evaluation; treatment varies according to the etiology. Craniosynostosis, a less common but pathological etiology for plagiocephaly, should be considered in the diagnostic process. Successful treatment of positional plagiocephaly and dolichocephaly includes systematic positioning changes to overcome the mechanical forces of repetitive positioning, physical and/or occupational therapy to treat underlying muscle or developmental challenges, and in some cases, molding helmet therapy. PMID:16338671

Hummel, Pat; Fortado, Dana

2005-12-01

399

Magnetic reconnection between small-scale loops observed with the New Vacuum Solar Telescope  

E-print Network

Using the high tempo-spatial resolution H$\\alpha$ images observed with the New Vacuum Solar Telescope, we report the 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 the 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 reconnect gradually, and new loops are formed and stacked together. During the rapid reconnection, the anti-parallel loops approach each other quickly, and then the rapid reconnection takes place, resulting in the disappearance of 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 an...

Yang, Shuhong; Xiang, Yongyuan

2014-01-01

400

Torque-Matched Aerodynamic Shape Optimization of HAWT Rotor  

NASA Astrophysics Data System (ADS)

Schmitz and Blade Element Momentum (BEM) theories are integrated to a gradient based optimization algorithm to optimize the blade shape of a horizontal axis wind turbine (HAWT). The Schmitz theory is used to generate an initial blade design. BEM theory is used to calculate the forces, torque and power extracted by the turbine. The airfoil shape (NREL S809) is kept the same, so that the shape optimization comprises only the chord and the pitch angle distribution. The gradient based optimization of the blade shape is constrained to the torque-rotational speed characteristic of the generator, which is going to be a part of the experimental set-up used to validate the results of the optimization study. Hence, the objective of the optimization is the maximization of the turbines power coefficient Cp while keeping the torque matched to that of the generator. The wind velocities and the rotational speeds are limited to those achievable in the wind tunnel and by the generator, respectively. After finding the optimum blade shape with the maximum Cp within the given range of parameters, the Cp of the turbine is evaluated at wind-speeds deviating from the optimum operating condition. For this purpose, a second optimization algorithm is used to find out the correct rotational speed for a given wind-speed, which is again constrained to the generator's torque rotational speed characteristic. The design and optimization procedures are later validated by high-fidelity numerical simulations. The agreement between the design and the numerical simulations is very satisfactory.

Al-Abadi, Ali; Ertun, zgr; Beyer, Florian; Delgado, Antonio

2014-12-01

401

A Shape Memory Polymer with Improved Shape Recovery  

Microsoft Academic Search

Thermally actuated shape memory polymers (SMPs) interest, both academically and industrially, due to their ability to memorize a permanent shape that is set during processing and a temporary shape that is later programmed by manipulation above a critical temperature, either Tg or Tm. However, the thermal triggering process for SMPs is usually retarded compared to that of shape memory alloys,

Changdeng Liu; Patrick T. Mather

2005-01-01

402

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

403

I Spy Shapes  

NSDL National Science Digital Library

The learner will ask yes-no questions to identify a secret shape (similar to Twenty Questions). Build understanding of shapes and logic skills with this game for all ages. The Leader secretly picks an object that everyone can see. The object should have a geometric shape, such as an equilateral triangle or sphere. The Leader announces: I see a [sphere]. The other players take turns asking yes-or-no questions to identify the object. They can ask about its color, position, or usebut they cant ask if it is a specific item in the room. When everyone has had at least two turns, each player may take a turn saying what the object could be and why. Available as a web page and downloadable pdf.

Terc

2010-01-01

404

Optimum design of capacitance sensor array for imaging the solids distribution of fluidized bed  

SciTech Connect

Fluidized beds are widely used in many industries. Fluidized bed combustion technique is rapidly developed and used to coal-fired power stations in order to improve the combustion efficiency and properties. Measuring the solids distributions of fluidized beds in furnaces are directly related to their working conditions and combustion efficiency, and furthermore are the basis of controlling the beds in the optimum run. Electrical capacitance tomography (ECT) systems recommended in this paper are non-intrusive and inexpensive being developed suitable for imaging density distributions in process pipelines, fluidization processes and so on. Considering that three-dimensional images are required in fluidization processes, several level electrodes are selected as the ECT systems' sensor array, which can provide 3D images by piling up many 2D sectional images. The aim of this paper is to select optimal structure parameters of the sensor array so as to reduce the influence between levels and to improve the properties of the images by use of the numerical tool of finite element method (FEM) and physical phantoms. First, a brief introduction of ECT systems was made and a sensor structure used for visualizing the fuel distributions in fluidized bed combustion was presented. And then, the orthogonal experimental design technique was carried out and a set of optimum sensor structure parameter was given by using fidelity of reconstructed image, spatial image error (SIE), as the optimum objective function. Finally, a comparison was made between two reconstructed images by the optimum structure and a non-optimum structure respectively, the results showed that the image by the non-optimum structure was with errors in gray-level and the SIE = 0 of the image by the optimum structure.

Xu, H.; Yan, H.; Wang, S.

1999-07-01

405

Elucidation of ultrafast photophysics with optical pulse shaping  

NASA Astrophysics Data System (ADS)

Optical pulse shaping is an incisive tool of laser spectroscopy that allows the experimentalist extensive flexibility to manipulate the electric field of an excitation laser pulse. In this thesis, four applications of optical pulse shaping are examined. In Chapter 2, a partially non-collinear implementation of two-dimensional electronic spectroscopy is demonstrated for the first time on rubidium vapor. The use of a pulse shaper in this context is advantageous as it significantly reduces the complexity of the experimental apparatus. Unfortunately, non-ideal pulse shaping due to pixelation effects in some pulse-shaping devices leads to spurious pulse generation when the spatial masks become highly modulated. To model the effects on recovered 2D spectra, the optical Bloch model is numerically propagated with an explicit inclusion of the electric field modified by pixelation effects. Finally, steps necessary to minimize distortions are outlined. Chapter 3 describes a series of experiments designed to study the mechanism of multiple exciton generation in semiconductor quantum dots through open and closed loop coherent control schemes. The data collected with open loop control methods indicate that the initially formed exciton relaxes on an ultrafast time scale (<20 fs) revealing the reason for a lack of controllability in adaptive, closed-loop optimizations. Chapter 4 of this thesis examines the process of singlet fission in tetracene thin films employing coherent control and ultrafast pulse shaping. Singlet fission is a promising avenue to achieving highly efficient third generation photovoltaic devices, and in this work, closed-loop control suggests that low-frequency nuclear motions play a mechanistic role in tetracene singlet fission. Finally, Chapter 5 examines a specific class of pulse shaping, sinusoidal spectral phase modulation, which is widely employed in the coherent control community as a route toward an intuitive probe into molecular dynamics. This work seeks to build a bridge between the fields of nonlinear spectroscopy and coherent control by describing the light-matter interactions characteristic of this type of pulse shaping using the tools of time-dependent perturbation theory. This description allows experimentalists to predict and test theories of coherent control simply and with little ambiguity, furthering the usefulness of coherent control as a spectroscopic tool.

Grumstrup, Erik Martin

406

Identify Current in a Magnetic Loop  

NSDL National Science Digital Library

A cross-section of a circular wire loop carrying an unknown current is shown in the animation. The user can add magnetic field lines, drag the center of the loop to reposition it, drag the top or bottom of the loop to change its size, and add a compass.

Wolfgang Christian

407

Rotation scheduling: a loop pipelining algorithm  

Microsoft Academic Search

We consider the resource-constrained scheduling of loops with interiteration dependencies. A loop is modeled as a data flow graph (DFG) , where edges are labeled with the number of iterations between dependencies. We design a novel and flexible technique, called rotation scheduling, for scheduling cyclic DFG's using loop pipelining. The rotation technique re- peatedly transforms a schedule to a more

Liang-Fang Chao; Andrea S. LaPaugh; Edwin Hsing-Mean Sha

1993-01-01

408

Some Aspects of Closed Control Loop Design  

Microsoft Academic Search

The paper describes a training course on the application of controllers in the closed control loops, where PID (Proportional-Integral- Derivative) instruction is most often used for control of continuous processes. An introduction to closed loop control technology is also provided. The basic structure of a closed control loop is explained. It enables to understand the interaction between the controlled system

Olga Ruban; Juhan Laugis

409

From Inductance Loops to Vehicle Trajectories  

E-print Network

from Phase 1 From Inductance Loops to Vehicle Trajectories ­ p.10/19 #12;Aerial View http://www.enm.bris.ac.uk/staff/rew/kml/m42_ivd_loops.kml From Inductance Loops to Vehicle Trajectories ­ p.11/19 #12;Layout of instrumented

Bertini, Robert L.

410

SP100 liquid metal test loop design  

Microsoft Academic Search

The SP-100 Power System Qualification (PSO) program validates the technology readiness of the SP-100 Generic Flight System (GFS). As part of the PSQ, the GFS reactor, heat transport and power generation systems are being validated, by test, in high temperature liquid metal test loops. The liquid metal test loop program consists of two test loops. The first, a natural circulation

T. Ted Fallas; Gordon B. Kruger; Frank R. Wiltshire; Grant C. Jensen; Harold Clay; Hugh A. Upton; Robert E. Gamble; Christian Kjaer-Olsen; Keith Lee

1992-01-01

411

Shapes and Angles  

NSDL National Science Digital Library

In this activity (page 7 of PDF), learners will identify the general two-dimensional geometric shape of the uppermost cross section of an impact crater. They will also draw connections between the general two-dimensional geometric shape of an impact crater and the projectile's angle of impact. There are two versions of this activity: Challenge, where students construct a launcher and create their own craters; and Non-Challenge where students analyze pictures of craters. The Moon Math: Craters! guide follows a 5E approach, applying concepts of geometry, modeling, data analysis to the NASA lunar spacecraft mission, LCROSS.

NASA

2012-05-08

412

Shapes of d Orbitals  

NSDL National Science Digital Library

Shapes of d Orbitals shows the d orbitals in an axis set. Running the mouse over an orbital reveals the "name" of that orbital. This is good practice for helping students link the name of an orbital to the orientation.Shapes of d Orbitals has a link to D Orbitals in an Octahedral Ligand Field. Here the user may click on the name of any one of the d orbitals to obtain a larger 3-dimensional image. The images are rotatable and scalable. Orbital phase is shown by the different colors.

413

The shape of Eros  

NASA Technical Reports Server (NTRS)

Monte Carlo simulations are presently used to optimize estimation, ascertain associated errors, and guide bias-correction procedures, for the Eros polar silhouette convex hull that has been estimated from radar echo spectra. This hull is trapezoidal; this nonaxisymmetric shape may account for odd harmonics in Eros' echo spectral signature as a function of rotation phase. Additional constraints have been obtained for the figure of Eros through the inversion of the optical lightcurve to estimate the asteroid's two-dimensional average of the three-dimensional shape. This 'mean cross-section' and the polar silhouette exhibit similar elongations.

Ostro, S. J.; Rosema, K. D.; Jurgens, R. F.

1990-01-01

414

Single anterior tooth replacement by a cast lingual loop connector - a conservative approach.  

PubMed

One of the most challenging and complex treatment modality is replacement of single anterior tooth. This can be overcome by different treatment options such as implant-supported restorations as well as conventional porcelain-fused-to-metal and resin-bonded fixed partial dentures. Drifting of teeth into the edentulous area may reduce the available pontic space; whereas a diastema existing before an extraction may result in excessive mesiodistal dimension to the pontic space. Loop connector fixed partial denture (FPD) may be the simplest and best solution to maintain the diastema and provide optimum restoration of aesthetics. This article describes the procedure for the fabrication of a loop connector FPD to restore an excessively wide anterior edentulous space in a patient with existing spacing between the maxillary anterior teeth. PMID:25386535

Dandekeri, Shilpa Sudesh; Dandekeri, Savita

2014-09-01

415

Loop-mediated isothermal amplification (LAMP) method for detection of genetically modified maize T25  

PubMed Central

The loop-mediated isothermal amplification (LAMP) assay indicates a potential and valuable means for genetically modified organism (GMO) detection especially for its rapidity, simplicity, and low cost. We developed and evaluated the specificity and sensitivity of the LAMP method for rapid detection of the genetically modified (GM) maize T25. A set of six specific primers was successfully designed to recognize six distinct sequences on the target gene, including a pair of inner primers, a pair of outer primers, and a pair of loop primers. The optimum reaction temperature and time were verified to be 65C and 45 min, respectively. The detection limit of this LAMP assay was 5 g kg?1 GMO component. Comparative experiments showed that the LAMP assay was a simple, rapid, accurate, and specific method for detecting the GM maize T25. PMID:24804053

Xu, Junyi; Zheng, Qiuyue; Yu, Ling; Liu, Ran; Zhao, Xin; Wang, Gang; Wang, Qinghua; Cao, Jijuan

2013-01-01

416

Computer program CORDET. [computerized simulation of digital phase-lock loop for Omega navigation receiver  

NASA Technical Reports Server (NTRS)

A FORTRAN 4 computer program provides convenient simulation of an all-digital phase-lock loop (DPLL). The DPLL forms the heart of the Omega navigation receiver prototype. Through the DPLL, the phase of the 10.2 KHz Omega signal is estimated when the true signal phase is contaminated with noise. This investigation has provided a convenient means of evaluating loop performance in a variety of noise environments, and has proved to be a useful tool for evaluating design changes. The goals of the simulation are to: (1) analyze the circuit on a bit-by-bit level in order to evaluate the overall design; (2) see easily the effects of proposed design changes prior to actual breadboarding; and (3) determine the optimum integration time for the DPLL in an environment typical of general aviation conditions.

Palkovic, R. A.

1974-01-01

417

Single Anterior Tooth Replacement by a Cast Lingual Loop Connector - A Conservative Approach  

PubMed Central

One of the most challenging and complex treatment modality is replacement of single anterior tooth. This can be overcome by different treatment options such as implant-supported restorations as well as conventional porcelain-fused-to-metal and resin-bonded fixed partial dentures. Drifting of teeth into the edentulous area may reduce the available pontic space; whereas a diastema existing before an extraction may result in excessive mesiodistal dimension to the pontic space. Loop connector fixed partial denture (FPD) may be the simplest and best solution to maintain the diastema and provide optimum restoration of aesthetics. This article describes the procedure for the fabrication of a loop connector FPD to restore an excessively wide anterior edentulous space in a patient with existing spacing between the maxillary anterior teeth. PMID:25386535

Dandekeri, Savita

2014-01-01

418

Polymeric triple-shape materials  

PubMed Central

Shape-memory polymers represent a promising class of materials that can move from one shape to another in response to a stimulus such as heat. Thus far, these systems are dual-shape materials. Here, we report a triple-shape polymer able to change from a first shape (A) to a second shape (B) and from there to a third shape (C). Shapes B and C are recalled by subsequent temperature increases. Whereas shapes A and B are fixed by physical cross-links, shape C is defined by covalent cross-links established during network formation. The triple-shape effect is a general concept that requires the application of a two-step programming process to suitable polymers and can be realized for various polymer networks whose molecular structure allows formation of at least two separated domains providing pronounced physical cross-links. These domains can act as the switches, which are used in the two-step programming process for temporarily fixing shapes A and B. It is demonstrated that different combinations of shapes A and B for a polymer network in a given shape C can be obtained by adjusting specific parameters of the programming process. Dual-shape materials have already found various applications. However, as later discussed and illustrated by two examples, the ability to induce two shape changes that are not limited to be unidirectional rather than one could potentially offer unique opportunities, such as in medical devices or fasteners. PMID:17116879

Bellin, I.; Kelch, S.; Langer, R.; Lendlein, A.

2006-01-01

419

Shape memory alloy thaw sensors  

DOEpatents

A sensor permanently indicates that it has been exposed to temperatures exceeding a critical temperature for a predetermined time period. An element of the sensor made from shape memory alloy changes shape when exposed, even temporarily, to temperatures above the Austenitic temperature of the shape memory alloy. The shape change of the SMA element causes the sensor to change between two readily distinguishable states.

Shahinpoor, Mohsen (Albuquerque, NM); Martinez, David R. (Albuquerque, NM)

1998-01-01

420

Developmental Differences in Shape Processing  

ERIC Educational Resources Information Center

Considerable evidence indicates that shape similarity plays a major role in object recognition, identification and categorization. However, little is known about shape processing and its development. Across four experiments, we addressed two related questions. First, what makes objects similar in shape? Second, how does the processing of shape

Sera, Maria D.; Gordon Millett, Katherine

2011-01-01

421

An Analytic Result for the Two-Loop Hexagon Wilson Loop in N = 4 SYM  

E-print Network

In the planar N=4 supersymmetric Yang-Mills theory, the conformal symmetry constrains multi-loop n-edged Wilson loops to be basically given in terms of the one-loop n-edged Wilson loop, augmented, for n greater than 6, by a function of conformally invariant cross ratios. We identify a class of kinematics for which the Wilson loop exhibits exact Regge factorisation and which leave invariant the analytic form of the multi-loop n-edged Wilson loop. In those kinematics, the analytic result for the Wilson loop is the same as in general kinematics, although the computation is remarkably simplified with respect to general kinematics. Using the simplest of those kinematics, we have performed the first analytic computation of the two-loop six-edged Wilson loop in general kinematics.

Vittorio Del Duca; Claude Duhr; Vladimir A. Smirnov

2009-11-27

422

Microgyroscope with closed loop output  

NASA Technical Reports Server (NTRS)

A micro-gyroscope (10) having closed loop operation by a control voltage (V.sub.TY), that is demodulated by an output signal of the sense electrodes (S1, S2), providing Coriolis torque rebalance to prevent displacement of the micro-gyroscope (10) on the output axis (y-axis). The present invention provides wide-band, closed-loop operation for a micro-gyroscope (10) and allows the drive frequency to be closely tuned to a high Q sense axis resonance. A differential sense signal (S1-S2) is compensated and fed back by differentially changing the voltage on the drive electrodes to rebalance Coriolis torque. The feedback signal is demodulated in phase with the drive axis signal (K.sub..omega..crclbar..sub.x) to produce a measure of the Coriolis force.

Challoner, A. Dorian (Inventor); Gutierrez, Roman C. (Inventor); Tang, Tony K. (Inventor); Cargille, Donald R. (Inventor)

2002-01-01

423

A portable anaerobic microbioreactor reveals optimum growth conditions for the methanogen Methanosaeta concilii.  

PubMed

Conventional studies of the optimum growth conditions for methanogens (methane-producing, obligate anaerobic archaea) are typically conducted with serum bottles or bioreactors. The use of microfluidics to culture methanogens allows direct microscopic observations of the time-integrated response of growth. Here, we developed a microbioreactor (microBR) with approximately 1-microl microchannels to study some optimum growth conditions for the methanogen Methanosaeta concilii. The microBR is contained in an anaerobic chamber specifically designed to place it directly onto an inverted light microscope stage while maintaining a N2-CO2 environment. The methanogen was cultured for months inside microchannels of different widths. Channel width was manipulated to create various fluid velocities, allowing the direct study of the behavior and responses of M. concilii to various shear stresses and revealing an optimum shear level of approximately 20 to 35 microPa. Gradients in a single microchannel were then used to find an optimum pH level of 7.6 and an optimum total NH4-N concentration of less than 1,100 mg/liter (<47 mg/liter as free NH3-N) for M. concilii under conditions of the previously determined ideal shear stress and pH and at a temperature of 35 degrees C. PMID:17220251

Steinhaus, Benjamin; Garcia, Marcelo L; Shen, Amy Q; Angenent, Largus T

2007-03-01

424

Exploring the optimum conditions for maximizing the microbial growth of Candida intermedia by response surface methodology.  

PubMed

Exploring optimum and cost-efficient medium composition for microbial growth of Candida intermedia Y-1981 yeast culture growing on whey was studied by applying a multistep response surface methodology. In the first step, Plackett-Burman (PB) design was utilized to determine the most significant fermentation medium factors on microbial growth. The medium temperature, sodium chloride and lactose concentrations were determined as the most important factors. Subsequently, the optimum combinations of the selected factors were explored by steepest ascent (SA) and central composite design (CCD). The optimum values for lactose and sodium chloride concentrations and medium temperature were found to be 18.4g/L, 0.161g/L, and 32.4C, respectively. Experiments carried out at the optimum conditions revealed a maximum specific growth rate of 0.090 1/hr; 42% of total lactose removal was achieved in 24h of fermentation time. The obtained results were finally verified with batch reactor experiments carried out under the optimum conditions evaluated. PMID:24117150

Ynten, Vahap; Akta?, Nahit

2014-01-01

425

Loop Virasoro Lie conformal algebra  

SciTech Connect

The Lie conformal algebra of loop Virasoro algebra, denoted by CW, is introduced in this paper. Explicitly, CW is a Lie conformal algebra with C[?]-basis (L{sub i} | i?Z) and ?-brackets [L{sub i}?{sub ?}?L{sub j}] = (???2?)L{sub i+j}. Then conformal derivations of CW are determined. Finally, rank one conformal modules and Z-graded free intermediate series modules over CW are classified.

Wu, Henan, E-mail: wuhenanby@163.com; Chen, Qiufan; Yue, Xiaoqing [Department of Mathematics, Tongji University, Shanghai 200092 (China)] [Department of Mathematics, Tongji University, Shanghai 200092 (China)

2014-01-15

426

Shaped Offset QPSK Capacity  

E-print Network

In this work we compute the capacities and the pragmatic capacities of military-standard shaped-offset quadrature phase-shift keying (SOQPSK-MIL) and aeronautical telemetry SOQPSK (SOQPSK-TG). In the pragmatic approach, SOQPSK is treated as a...

Sahin, Cenk

2012-08-31

427

3D Shape Match  

NSDL National Science Digital Library

This interactive Flash applet provides a Concentration-type game (called pelmanism in the UK) in which students must discern the properties of three-dimensional solids and their colors in order to match them in pairs. Spheres, cones, prisms and other standard 3-D shapes are hidden face down on cards. Time and number of trials needed to solve are recorded.

Bunker, Dan

2011-01-01

428

Volume and Shapes  

NSDL National Science Digital Library

This one and a half minute video shows a classroom of students working on an activity that utilizes linking cubes to demonstrate the relationship between three-dimensional shapes and their volume. Included with the video is a background essay on volume and discussion questions.

2006-01-01

429

The Shapes of Physics  

ERIC Educational Resources Information Center

I have used many ploys to start a course in introductory physics, but one of the more interesting ones was to spend 20 minutes describing some of the curves and shapes that we would encounter in our year together. The students saw parabolas, catenaries, hyperbolas, cycloids, circles, ellipses, and helices, and were shown examples, either live or

Greenslade, Thomas B., Jr.

2013-01-01

430

Shape anisotropy and Voids  

E-print Network

Numerical simulations on a 2-dimensional model system showed that voids are induced primarily due to shape anisotropy in binary mixtures of interacting disks. The results of such a simple model account for the key features seen in a variety of flux experiments using liposomes and biological membranes.

Gauri R. Pradhan; Sagar A. Pandit; Anil D. Gangal; V. Sitaramam

2000-02-10

431

Shape Memory Alloy Actuator  

NASA Technical Reports Server (NTRS)

The present invention discloses and teaches a unique, remote optically controlled micro actuator particularly suitable for aerospace vehicle applications wherein hot gas, or in the alternative optical energy, is employed as the medium by which shape memory alloy elements are activated. In gas turbine powered aircraft the source of the hot gas may be the turbine engine compressor or turbine sections.

Baumbick, Robert J. (Inventor)

2000-01-01

432

Shape Memory Alloy Actuator  

NASA Technical Reports Server (NTRS)

The present invention discloses and teaches a unique, remote optically controlled micro actuator particularly suitable for aerospace vehicle applications wherein hot gas, or in the alternative optical energy, is employed as the medium by which shape memory alloy elements are activated. In gas turbine powered aircraft the source of the hot gas may be the turbine engine compressor or turbine sections.

Baumbick, Robert J. (Inventor)

2002-01-01

433

Size and Shape  

NSDL National Science Digital Library

Size and shape are important in astrobiology. In this activity and slideshow, students observe the importance of relative size and morphology in identifying microscopic structures when viewed with the scanning electron microscope. This activity is part of an astrobiology guide called the "Fingerprints of Life" which contains background information for students, worksheets, extension activities, suggested assessments, and alignment to standards.

434

What Shape Is It?  

NSDL National Science Digital Library

In this activity, learners determine the shape of an unseen object by bouncing a ball off the object. Learners analyze how the ball hits the object (the angle at which it strikes the surface) to figure out the path it will take. Use this activity to explain how physicists study subatomic particles (e.g. electrons, protons, neutrons).

Kansas, University O.

2006-01-01

435

Geometric Shapes in Architecture  

NSDL National Science Digital Library

A unit designed to improve students' understanding and appreciation of basic geometric shapes used in architecture. It describes various plane geometric figures and discusses in detail the properties of several of these figures. Perimeters and areas of polygons and circles are computed.

Fox, Lauretta J.

2007-02-22

436

Shaping Adolescent Gambling Behavior.  

ERIC Educational Resources Information Center

Surveyed the incidence of casino gambling by adolescents. Results indicated that 64 percent of the students at one Atlantic City high school had gambled at the casinos. The dangers of shaping compulsive gambling behavior through societal acceptance of legalized gambling are discussed. (Author/BL)

Arcuri, Alan F.; And Others

1985-01-01

437

The Shape Song  

NSDL National Science Digital Library

This video features a sing-along song about shapes. The first half of this song is for preschoolers: circle, triangle, rectangle, square. The second half is for primary grade students: oval, diamond, heart, crescent, rhombus, trapezoid, pentagon, hexagon, heptagon, and octagon.

Grancie48

2011-06-17

438

Alpha shapes applied to molecular shape characterization exhibit novel properties compared to established shape descriptors  

PubMed Central

Despite considerable efforts, description of molecular shape is still largely an unresolved problem. Given the importance of molecular shape in the description of spatial interactions in crystals or ligand-target complexes, this is not a satisfying state. In the current work, we propose a novel application of alpha shapes to the description of the shapes of small molecules. Alpha shapes are parameterized generalizations of the convex hull. For a specific value of ?, the alpha shape is the geometric dual of the space-filling model of a molecule, with the parameter ? allowing description of shape in varying degrees of detail. To date, alpha shapes have been used to find macromolecular cavities and to estimate molecular surface areas and volumes. We developed a novel methodology for computing molecular shape characteristics from the alpha shape. In this work, we show that alpha-shape descriptors reveal aspects of molecular shape that are complementary to other shape descriptors, and that accord well with chemists intuition about shape. While our implementation of alpha-shape descriptors is not computationally trivial, we suggest that the additional shape characteristics they provide can be used to improve and complement shape-analysis methods in domains such as crystallography and ligand-target interactions. In this communication, we present a unique methodology for computing molecular shape characteristics from the alpha shape. We first describe details of the alpha-shape calculation, an outline of validation experiments performed, and a discussion of the advantages and challenges we found while implementing this approach. The results show that, relative to known shape calculations, this method provides a high degree of shape resolution with even small changes in atomic coordinates. PMID:19775113

Wilson, J. Anthony; Bender, Andreas; Kaya, Taner; Clemons, Paul A.

2011-01-01

439

High frequency, high temperature specific core loss and dynamic B-H hysteresis loop characteristics of soft magnetic alloys  

NASA Technical Reports Server (NTRS)

Limited experimental data exists for the specific core loss and dynamic B-H loop for soft magnetic materials for the combined conditions of high frequency and high temperature. This experimental study investigates the specific core loss and dynamic B-H loop characteristics of Supermalloy and Metglas 2605SC over the frequency range of 1 to 50 kHz and temperature range of 23 to 300 C under sinusoidal voltage excitation. The experimental setup used to conduct the investigation is described. The effects of the maximum magnetic flux density, frequency, and temperature on the specific core loss and on the size and shape of the B-H loops are examined.

Wieserman, W. R.; Schwarze, G. E.; Niedra, J. M.

1990-01-01

440

High frequency, high temperature specific core loss and dynamic B-H hysteresis loop characteristics of soft magnetic alloys  

NASA Technical Reports Server (NTRS)

Limited experimental data exists for the specific core loss and dynamic B-H loops for soft magnetic materials for the combined conditions of high frequency and high temperature. This experimental study investigates the specific core loss and dynamic B-H loop characteristics of Supermalloy and Metglas 2605SC over the frequency range of 1 to 50 kHz and temperature range of 23 to 300 C under sinusoidal voltage excitation. The experimental setup used to conduct the investigation is described. The effects of the maximum magnetic flux density, frequency, and temperature on the specific core loss and on the size and shape of the B-H loops are examined.

Wieserman, W. R.; Schwarze, G. E.; Niedra, J. M.

1990-01-01

441

Loop-synchronous polarization scrambling technique for simulating polarization effects using recirculating fiber loops  

Microsoft Academic Search

A loop-synchronous polarization-scrambling technique has been proposed for the purpose of simulating polarization effects in straight-line systems using recirculating loops. This technique uses a fast polarization controller within a fiber loop. The polarization controller changes its transmission matrix after each round trip of the optical signal circulating through the loop; thus, the periodic polarization transform of the loop is avoided.

Q. Yu; L.-S. Yan; S. Lee; Y. Xie; A. E. Willner

2003-01-01

442

The loop-tree duality at work  

E-print Network

We review the recent developments of the loop-tree duality method, focussing our discussion on analysing the singular behaviour of the loop integrand of the dual representation of one-loop integrals and scattering amplitudes. We show that within the loop-tree duality method there is a partial cancellation of singularities at the integrand level among the different components of the corresponding dual representation. The remaining threshold and infrared singularities are restricted to a finite region of the loop momentum space, which is of the size of the external momenta and can be mapped to the phase-space of real corrections to cancel the soft and collinear divergences.

Sebastian Buchta; Grigorios Chachamis; Ioannis Malamos; Isabella Bierenbaum; Petros Draggiotis; German Rodrigo

2014-07-22

443

Improvement of the Optimum pH of Aspergillus niger Xylanase towards an Alkaline pH by Site-Directed Mutagenesis.  

PubMed

In an attempt to shift the optimal pH of the xylanase B (XynB) from Aspergillus niger towards alkalinity, target mutation sites were selected by alignment between Aspergillus niger xylanase B and other xylanases that have alkalophilic pH optima that highlight charged residues in the eight-residues-longer loop in the alkalophilic xylanase. Multiple engineered XynB mutants were created by site-directed mutagenesis with substitutions Q164K and Q164K+D117N. The variant XynB-117 had the highest optimum pH (at 5.5), which corresponded to a basic 0.5 pH unit shift when compared with the wild-type enzyme. However, the optimal pH of the XynB- 164 mutation was not changed, similar to the wild type. These results suggest that the residues at positions 164 and 117 in the eight-residues-longer loop and the cleft's edge are important in determining the pH optima of XynB from Aspergillus niger. PMID:25152057

Li, Fei; Xie, Jingcong; Zhang, Xuesong; Zhao, Linguo

2015-01-28

444

Closing the ring: a fourth extracellular loop in chemokine receptors.  

PubMed

Chemokine receptors are heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCR) that play fundamental roles in many physiological and pathological processes. Typically, these receptors form a seven-transmembrane helix bundle, which is stabilized by a disulfide bond bridging the top of the third transmembrane segment (TM3) and the second extracellular loop (ECL2). Resolution of the three-dimensional structures of the chemokine receptors CXCR1, CXCR4, and CCR5 revealed the existence of a second disulfide bridge that links the N terminus of the receptor to the top of the seventh transmembrane segment (TM7), thereby closing the receptor into a ring. An important consequence of this second disulfide bond is the formation of an additional extracellular loop, which shapes the entrance of the ligand-binding pocket and adds rigidity to the overall surface of the receptor. Here, we discuss the features of these "pseudo-loops," the structural requirements for their formation, and the effects they may have on receptor function. PMID:25185155

Szpakowska, Martyna; Perez Bercoff, Danielle; Chevign, Andy

2014-09-01

445

Shape design sensitivity analysis and optimization of three dimensional elastic solids using geometric modeling and automatic regridding. Ph.D. Thesis  

NASA Technical Reports Server (NTRS)

An automatic regridding method and a three dimensional shape design parameterization technique were constructed and integrated into a unified theory of shape design sensitivity analysis. An algorithm was developed for general shape design sensitivity analysis of three dimensional eleastic solids. Numerical implementation of this shape design sensitivity analysis method was carried out using the finite element code ANSYS. The unified theory of shape design sensitivity analysis uses the material derivative of continuum mechanics with a design velocity field that represents shape change effects over the structural design. Automatic regridding methods were developed by generating a domain velocity field with boundary displacement method. Shape design parameterization for three dimensional surface design problems was illustrated using a Bezier surface with boundary perturbations that depend linearly on the perturbation of design parameters. A linearization method of optimization, LINRM, was used to obtain optimum shapes. Three examples from different engineering disciplines were investigated to demonstrate the accuracy and versatility of this shape design sensitivity analysis method.

Yao, Tse-Min; Choi, Kyung K.

1987-01-01

446

Sequence alignments in the neighborhood of the optimum with general application to dynamic programming  

PubMed Central

When applying dynamic programming techniques to obtain optimal sequence alignments, a set of weights must be assigned to mismatches, insertion/deletions, etc. These weights are not predetermined, although efforts are being made to deduce biologically meaningful values from data. In addition, there are sometimes unknown constraints on the sequences that cause the true alignment to disagree with the optimum (computer) solution. To assist in overcoming these difficulties, an algorithm has been developed to produce all alignments within a specified distance of the optimum. The distance can be chosen after the optimum is computed, and the algorithm can be repeated at will. Earlier algorithms to solve this problem were very complex and not practical for any case involving sequences with significant time or storage requirements. The algorithm presented here overcomes these difficulties and has application to general, discrete dynamic programming problems. PMID:16593315

Waterman, Michael S.

1983-01-01

447

Optimum antireflection coating for Antireflection-coated Metal-Oxide-Semiconductor /AMOS/ solar cells  

NASA Technical Reports Server (NTRS)

Consideration is given to the design of a single-layer optimum antireflection coating for AMOS (antireflection-coated metal-oxide-semiconductor) solar cells to match the entire sunlight spectrum. The energy conversion efficiency is maximized by maximizing the open-circuit voltage and the short-circuit current. The former is maximized by oxidation techniques and the latter is maximized by the light-coupling into the solar cell. With reference to the effective index of refraction as obtained by ellipsometry, examples of optimum antireflection coatings for 60-A Au-GaAs solar cells are presented.

Yeh, Y. C. M.; Ernest, F. P.; Stirn, R. J.

1977-01-01

448

Application of Modified Least Squares Method to a Space Curve Generating Mechanism for Optimum Synthesis  

NASA Astrophysics Data System (ADS)

Synthesis of mechanisms for generation of space curve is a challenging task for designers of the mechanical systems. Least squares method (LSM) has been extensively used for optimization of both planar and spatial mechanisms. Modified least squares method is applied for optimum synthesis of a slotted link mechanism with flexibly attached slider for space curve generation to show the scope of the modified method for optimum design. An example problem is included to illustrate the application of the method. Results are compared with conventional LSM.

Baishya, N. J.; Sharma, D.; Dixit, U. S.

2014-11-01

449

Magnetic damping forces in figure-eight-shaped null-flux coil suspension systems  

Microsoft Academic Search

This paper discusses magnetic damping forces in figure-eight-shaped null-flux coil suspension systems, focusing on the Holloman Maglev rocket system. The paper also discusses simulating the damping plate, which is attached to the superconducting magnet by two short-circuited loop coils interacting with the figure-eight-shaped null-flux coils in the guideway. Closed-form formulas for the magnetic damping coefficient as functions of heave-and-sway displacements

Jianliang He; H. Coffey

1997-01-01

450

Shaping up for action  

PubMed Central

The Malpighian tubule is the main organ for excretion and osmoregulation in most insects. During a short period of embryonic development the tubules of Drosophila are shaped, undergo differentiation and become precisely positioned in the body cavity, so they become fully functional at the time of larval hatching a few hours later. In this review I explore three developmental events on the path to physiological maturation. First, I examine the molecular and cellular mechanisms that generate organ shape, focusing on the process of cell intercalation that drives tubule elongation, the roles of the cytoskeleton, the extracellular matrix and how intercalation is coordinated at the tissue level. Second, I look at the genetic networks that control the physiological differentiation of tubule cells and consider how distinctive physiological domains in the tubule are patterned. Finally, I explore how the organ is positioned within the body cavity and consider the relationship between organ position and function. PMID:23445869

Denholm, Barry

2013-01-01

451

Equilibrium shape of Si  

Microsoft Academic Search

Small voids are formed in Si by MeV He implantation and annealing. We measure the equilibrium shape of these voids and hence extract the surface energy curve gamma(theta) for Si. gamma(111) is the global minimum, with gamma(100)~=1.1gamma(111) and all other cusps on the surface being relatively small. The experimental gamma(theta) is compared with theoretical predictions and earlier experiments. Step energies

D. J. Eaglesham; A. E. White; L. C. Feldman; N. Moriya; D. C. Jacobson

1993-01-01

452

Building with Solid Shapes  

NSDL National Science Digital Library

This problem helps children begin to understand the various properties of common geometric solid shapes. It also promotes naming, discussion and experimentation concerning their features, and requires them to justify their ideas. It asks students to judge the stability of nine configurations made from six common solids. The Teachers' Notes page includes suggestions for implementation, discussion questions, ideas for extension and support, and printable sheets.

453

Imaging by shape  

NASA Astrophysics Data System (ADS)

Quantitative phase imaging generates the refractive and thickness structure of transparent samples in transmission light microscopy. It is a method that utilises the fact that a phase distribution in one plane has visible outcomes on the intensity of the wave as it propagates. This paper shows equivalent shape imaging results appear possible for through-focal stacks in reflection microscope imaging. Comparison is made to the transmission formulation and images to show the appropriateness of the results.

Allman, Brendan E.; Gregson, Gavin P.; Nugent, Keith A.

2006-05-01

454

Shape memory alloy actuator  

DOEpatents

An actuator for cycling between first and second positions includes a first shaped memory alloy (SMA) leg, a second SMA leg. At least one heating/cooling device is thermally connected to at least one of the legs, each heating/cooling device capable of simultaneously heating one leg while cooling the other leg. The heating/cooling devices can include thermoelectric and/or thermoionic elements.

Varma, Venugopal K. (Knoxville, TN)

2001-01-01

455

Oriented active shape models  

NASA Astrophysics Data System (ADS)

Active Shape Models (ASM) are widely employed for recognizing anatomic structures and for delineating them in medical images. In this paper, we present a novel strategy called Oriented Active Shape Models (OASM) in an attempt to overcome the following three major limitations of ASM: (1) poor delineation accuracy, (2) the requirement of a large number of landmarks, (3) the problem of sensitivity to search range to recognize the object boundary. OASM effectively combines the rich statistical shape information embodied in ASM with the boundary orientedness property and the globally optimal delineation capability of the live wire methodology of boundary segmentation. The latter allow live wire to effectively separate an object boundary from other non object boundaries with similar properties that come very close in the image domain. Our approach leads us to a 2-level dynamic programming method, wherein the first level corresponds to boundary recognition and the second level corresponds to boundary delineation. Our experiments in segmenting breast, liver, bones of the foot, and cervical vertebrae of the spine in MR and CT images indicate the following: (1) The accuracy of segmentation via OASM is considerably better than that of ASM. (2) The number of landmarks can be reduced by a factor of 3 in OASM over that in ASM. (3) OASM becomes largely independent of search range. All three benefits of OASM ensue mainly from the severe constraints brought in by the boundary-orientedness property of live wire and the globally optimal solution of dynamic programming.

Liu, Jiamin; Udupa, Jayaram K.

2006-03-01

456

Plasma condensation in coronal loops  

NASA Astrophysics Data System (ADS)

Aims:Using temporal series data from the Coronal Diagnostic Spectrometer (CDS) on SOHO, we seek to investigate plasma condensation through the use of spectroscopic analysis. Methods: Using a space-time (X-T) type plot we show, for a number of transition region (TR) and coronal lines, the variation of intensity (radiant flux) with time in an off-limb loop system. Noting a number of pixels where the intensity shows a sharp jump in value for the TR lines and a corresponding sharp decrease for the coronal lines, we investigate further and plot the intensity and velocity for these pixels as a function of time. Using standard Fourier techniques, together with a pre-whitening method, we measure all statistically significant frequencies present in the time series so created. Results: We find that, for the cooler lines of He I 584 and O V 629 , there are sharp increases in intensity, accompanied by large blueshifted velocities. In the case of O V there is a substantial rebound to redshifted velocities when the strong brightening fades. The sharp increase in intensity and blueshifted velocity in the cooler lines is accompanied by a corresponding decrease in the intensity of the coronal lines (Mg X 624 , Fe XVI 360 , Si XII 520 ), but with no corresponding change in their velocity values implying an evacuation of plasma. From the Fourier analysis, evidence is found for possible 1st and 2nd harmonics in the He I and O V lines, indicative of standing waves in loops. Conclusions: We conclude that what we are seeing is the first spectroscopic evidence of plasma condensation taking place in coronal loops. A movie is only available in electronic form at http://www.aanda.org

O'Shea, E.; Banerjee, D.; Doyle, J. G.

2007-11-01

457

MutS mediates heteroduplex loop formation by a translocation mechanism.  

PubMed Central

Interaction of Escherichia coli MutS and MutL with heteroduplex DNA has been visualized by electron microscopy. In a reaction dependent on ATP hydrolysis, complexes between a MutS dimer and a DNA heteroduplex are converted to protein-stabilized, alpha-shaped loop structures with the mismatch in most cases located within the DNA loop. Loop formation depends on ATP hydrolysis and loop size increases linearly with time at a rate of 370 base pairs/min in phosphate buffer and about 10,000 base pairs/min in the HEPES buffer used for repair assay. These observations suggest a translocation mechanism in which a MutS dimer bound to a mismatch subsequently leaves this site by ATP-dependent tracking or unidimensional movement that is in most cases bidirectional from the mispair. In view of the bidirectional capability of the methyl-directed pathway, this reaction may play a role in determination of heteroduplex orientation. The rate of MutS-mediated DNA loop growth is enhanced by MutL, and when both proteins are present, both are found at the base of alpha-loop structures, and both can remain associated with excision intermediates produced in later stages of the reaction. PMID:9250691

Allen, D J; Makhov, A; Grilley, M; Taylor, J; Thresher, R; Modrich, P; Griffith, J D

1997-01-01

458

Using Waits, Loops and Switches  

NSDL National Science Digital Library

Students are given a difficult challenge that requires they integrate what they have learned so far in the unit about wait blocks, loops and switches. They incorporate these tools into their programming of the LEGO® MINDSTORMS® NXT robots to perform different tasks depending on input from a sound sensor and two touch sensors. This activity helps students understand how similar logic is implemented for other every day device operations via computer programs. A PowerPoint® presentation, pre/post quizzes and worksheet are provided.

GK-12 Program, Computational Neurobiology Center,

459

OPTIMUM MACROBENTHIC SAMPLING PROTOCOL FOR DETECTING POLLUTION IMPACTS IN THE SOUTHERN CALIFORNIA BIGHT  

EPA Science Inventory

The optimum macrobenthic sampling protocol sampling unit, sieve mesh size, and sample size (n)] was determined for detecting ecologically important pollution impacts in the Southern California Bight, U.S.A. Cost, in laboratory processing time, was determined for samples obtained ...

460

VARIABILITY IN OBSERVED AND SENSOR BASED ESTIMATED OPTIMUM N RATES IN CORN  

Technology Transfer Automated Retrieval System (TEKTRAN)

Recent research showed that active sensors such as Crop Circle can be used to estimate in-season N requirements in corn. The objective of this research was to identify the sources of variability in the observed and estimated economic optimum N rates (EONR) using Crop Circle. Field experiments were c...

461

Within-field variability in optimum nitrogen rate for corn linked to soil moisture variability  

Technology Transfer Automated Retrieval System (TEKTRAN)

Understanding the interaction between yield response to N and other growth-limiting factors is essential to improving spatially dependent N fertilizer applications. Our objective was to evaluate the impact of soil water content variability on the economic optimum N rate (EONR) for corn (Zea mays L.)...

462

Variability in Observed and Sensor Based Estimated Optimum N Rates in Corn  

Technology Transfer Automated Retrieval System (TEKTRAN)

Recent research showed that active sensors such as Crop Circle can be used to estimate in-season N requirements for corn. The objective of this research was to identify sources of variability in the observed and Crop Circle-estimated optimum N rates. Field experiments were conducted at two locations...

463

Weather radar polarimetry: path integrated differential phase shift optimum polarization and the elliptical EF-basis  

Microsoft Academic Search

Polarimetric pulsed Doppler radar measurements of meteorological targets yield mean backscattering properties of hydrometeors in the considered range cells and provide information on propagation effects along the radar ray of propagation. In this paper, two aspects of choosing an optimum polarimetric measurement basis are examined. First, the polarization dependence of path integrated differential phase shift is studied starting from the

V. Ziegler; E. Lneburg; A. Schroth

1995-01-01

464

Engine performance and optimum injection timing for 4-cylinder direct injection hydrogen fueled engine  

Microsoft Academic Search

This paper presents the engine performance and optimum injection timing for 4-cylinder direct injection hydrogen fueled engine. The 4-cylinder direct injection hydrogen engine model was developed utilizing the GT-Power commercial software. This model employed one dimensional gas dynamics to represent the flow and heat transfer in the components of engine model. Sequential pulse injectors are adopted to inject hydrogen gas

M. M. Rahman; Mohammed Kamil; Rosli A. Bakar

2011-01-01

465

Optimum Filter Design for a Single-Phase Solid-State UPS System  

Microsoft Academic Search

A systematic design procedure for the output filter of a singlephase uninterruptible power supply (UPS) system is developed. The basic specifications for the UPS system are first established. Four different output filter configurations are then analyzed and compared for sinusoidal pulsewidth and single-pulse modulated inverter output (i.e., filter input) voltage. On the basis of the above comparison, ``optimum'' filters are

S. B. Dewan; P. D. Ziogas

1979-01-01

466

OPTIMUM N:P RATIOS AND COEXISTENCE OF PLANKTONIC ALGAE (JOURNAL VERSION)  

EPA Science Inventory

The optimum atomic ratio of N to P, the ratio at which one nutrient limitation changes over the other, was determined in seven species of freshwater planktonic algae. The ratio varied over a wide range among species; the average for these species was 17. If the cellular nutrient ...

467

Optimum feed temperatures for seawater reverse osmosis plant operation in an MSF\\/SWRO hybrid plant  

Microsoft Academic Search

In this study it is shown that there is a relatively low optimum feed water temperature to a SWRO plant to maximise the lifetime production of a typical B10 permeator. This is based on the calculation methods outlined in the Dupont Permasep Manuals. The results tend to indicate that, in the case of these particular membranes and in typical Middle

Z. K. Al-Bahri; W. T. Hanbury; T. Hodgkiess

2001-01-01

468

Design of recursive digital filters with optimum magnitude and attenuation poles on the unit circle  

Microsoft Academic Search

A class of infinite impulse response (IIR) digital filters with optimum magnitude in the Chebyshev sense, arbitrary attenuation in the passband and stopband, all zeros on the unit circle, and different order numerator and denominator is discussed. Several properties of low-pass filters of this type are described, such as the effect of an extra ripple in the passband and the

H. Martinez; T. Parks

1978-01-01

469

ALIMENTATION Contribution to the definition of an optimum level of energy restriction  

E-print Network

ALIMENTATION FEEDING Contribution to the definition of an optimum level of energy restriction), the daily crude protein supply being similar. During lactation, all the sows were fed the same 15 p. 100 protein diet. Results recorded until 7 reproductive cycles concerned a total of 360 litters per diet

Paris-Sud XI, Université de

470

Optimum aperture size and operating temperature of a solar cavity-receiver  

Microsoft Academic Search

For solar cavity-receivers operating at high temperatures, the optimum aperture size results from a compromise between maximizing radiation capture and minimizing radiation losses. When the absorbed solar energy is utilized as high temperature process heat, the energy conversion efficiency can be represented as the product of the energy absorption efficiency and the Carnot efficiency. The authors describe a simple, semiempirical

A. Steinfeld; M. Schubnell

1993-01-01

471

Thermodynamic length, time, speed, and optimum path to minimize entropy production  

Microsoft Academic Search

In addition to the Riemannian metricization of the thermodynamic state space, local relaxation times offer a natural time scale, too. Generalizing existing proposals, we relate {\\\\it thermodynamic} time scale to the standard kinetic coefficients of irreversible thermodynamics. Criteria for minimum entropy production in slow, slightly irreversible processes are discussed. Euler-Lagrange equations are derived for optimum thermodynamic control for fixed clock-time

L. Disi; K. Kulacsy; B. Lukcs; A. Rcz

1996-01-01

472

Determination of the Optimum Directional Angles of Ultrasonic Oscillation in Testing Seamless Thick-Wall Pipes  

Microsoft Academic Search

A method is proposed for determining the optimum angles at which ultrasonic waves must be directed in the pipe body for the purpose of testing the pipe quality by means of the ultrasonic test method that employs shear waves propagating in the pipe wall along a zigzag trajectory perpendicularly to the generatrix.

V. I. Uvarov; A. S. Sedykhov; S. S. Taroyants

2001-01-01

473

Spoken emotion recognition through optimum-path forest classification using glottal features  

Microsoft Academic Search

A new method for the recognition of spoken emotions is presented based on features of the glottal airflow signal. Its effectiveness is tested on the new optimum path classifier (OPF) as well as on six other previously established classification methods that included the Gaussian mixture model (GMM), support vector machine (SVM), artificial neural networks multi layer perceptron (ANN-MLP), k-nearest

Alexander I. Iliev; Michael S. Scordilis; Joo P. Papa; Alexandre X. Falco

2010-01-01

474

Buried Object Detection Method Using Optimum Frequency Range in Extremely Shallow Underground  

NASA Astrophysics Data System (ADS)

We propose a new detection method for buried objects using the optimum frequency response range of the corresponding vibration velocity. Flat speakers and a scanning laser Doppler vibrometer (SLDV) are used for noncontact acoustic imaging in the extremely shallow underground. The exploration depth depends on the sound pressure, but it is usually less than 10 cm. Styrofoam, wood (silver fir), and acrylic boards of the same size, different size styrofoam boards, a hollow toy duck, a hollow plastic container, a plastic container filled with sand, a hollow steel can and an unglazed pot are used as buried objects which are buried in sand to about 2 cm depth. The imaging procedure of buried objects using the optimum frequency range is given below. First, the standardized difference from the average vibration velocity is calculated for all scan points. Next, using this result, underground images are made using a constant frequency width to search for the frequency response range of the buried object. After choosing an approximate frequency response range, the difference between the average vibration velocity for all points and that for several points that showed a clear response is calculated for the final confirmation of the optimum frequency range. Using this optimum frequency range, we can obtain the clearest image of the buried object. From the experimental results, we confirmed the effectiveness of our proposed method. In particular, a clear image of the buried object was obtained when the SLDV image was unclear.

Sugimoto, Tsuneyoshi; Abe, Touma

2011-07-01

475

Genetic algorithm based system identification and PID tuning for optimum adaptive control  

Microsoft Academic Search

In this paper the genetic algorithm optimization technique, is successfully applied in system identification and PID tuning for optimum adaptive control. In the proposed approach, two independent genetic algorithms were used sequentially. The first one is used for system model identification and the second one for PID controller tuning. Once the plant model was identified the parameters found are used

Dionisio S. Pereira; Joo O. P. Pinto

2005-01-01

476

The search for optimum condenser cooling water flow rate in a thermal power plant  

Microsoft Academic Search

Heat losses from the thermal power plant cycle are due mainly to heat rejection through the condenser. Operating the condenser at optimum circulation water flowrate is essentially important to ensure maximum efficiency and minimum operating cost of the plant. In this study, computer program codes were developed in Microsoft Excel macros for simulation of a thermal plant at various circulation

A. N. Anozie; O. J. Odejobi

2011-01-01

477

ACTIVE HAIR-BUNDLE MOTILITY HARNESSES NOISE TO OPERATE NEAR AN OPTIMUM OF MECHANOSENSITIVITY  

E-print Network

ACTIVE HAIR-BUNDLE MOTILITY HARNESSES NOISE TO OPERATE NEAR AN OPTIMUM OF MECHANOSENSITIVITY P sensitivity and frequency selectivity. In the bullfrog's sacculus, a hair cell can mobilize active oscillatory movements of its hair bundle to amplify its response to faint stimuli. Hair-bundle oscillations can result

Jülicher, Frank

478

Active hair-bundle motility harnesses noise to operate near an optimum of mechanosensitivity  

E-print Network

Active hair-bundle motility harnesses noise to operate near an optimum of mechanosensitivity Bjo of an oscillatory instability, a Hopf bifurcation. In the bullfrog's sacculus, a hair cell can display spontaneous oscillations of its mechanosensory hair bundle. The behavior of an oscillatory hair bundle resembles

Jülicher, Frank

479

Optimum and maximum temperatures of sockeye salmon (Oncorhynchus nerka) populations hatched at different temperatures  

E-print Network

ARTICLE Optimum and maximum temperatures of sockeye salmon (Oncorhynchus nerka) populations hatched: Temperature tolerance and heart rates were compared among nine sockeye salmon (Oncorhynchus nerka (Walbaum variance is adaptive, or a constraint, or both. Key words: sockeye salmon, Oncorhynchus nerka, critical

Hinch, Scott G.

480

Optimum Design and Development of an XY Flexure Micromanipulator for Micro Scale Positioning  

E-print Network

a parallel compliant mechanism actuated with three two-axis thermo-mechanical micro-actuators [2Optimum Design and Development of an XY Flexure Micromanipulator for Micro Scale Positioning procedures of a new decoupled XY micromanipulator for micro scale positioning applications. The manipulator

Li, Yangmin

481

Controlled therapeutic trial to determine the optimum dose of antacids in duodenal ulcer  

Microsoft Academic Search

Antacids are widely used in the management of duodenal ulcer but the optimum dose of antacid required for ulcer healing has not been determined. We therefore studied 107 patients with endoscopically diagnosed duodenal ulcer who were allotted at random to one of the following treatment groups; placebo (group P) and antacid (groups A, B and C). A liquid antacid (Aludrox

N Kumar; J C Vij; A Karol; B S Anand

1984-01-01

482

Iteration Bound Analysis and Throughput Optimum Architecture of SHA-256 (384,512) for  

E-print Network

. The hash algorithm forms the basis of many popular crypto- graphic protocols and it is therefore importantIteration Bound Analysis and Throughput Optimum Architecture of SHA-256 (384,512) for Hardware iteration bound analysis on the SHA2 family of hash algorithms. Using this technique, we are able to both

Verbauwhede, Ingrid

483

Novel direct and self-regulating approaches to determine optimum growing multi-experts network structure  

Microsoft Academic Search

This work presents two novel approaches to determine optimum growing multi-experts network (GMN) structure. The first method called direct method deals with expertise domain and levels in connection with local experts. The growing neural gas (GNG) algorithm is used to cluster the local experts. The concept of error distribution is used to apportion error among the local experts. After reaching

Chu Kiong Loo; Mandava Rajeswari; M. V. C. Rao

2004-01-01

484

Optimum arrangement for the neutron dose rate of an iron-polyethylene shielding system  

SciTech Connect

Integral shielding experiments using iron-polyethylene slab shields were carried out to determine an optimum arrangement for the neutron dose rate. The total thickness of the iron slabs was fixed at 32 cm, while several thicknesses of polyethylene slabs were employed as a parameter. Some measured data were analyzed by the Mone Carlo code MORSE-CG with the splitting technique.

Ueki, K.; Namito, Y.

1987-05-01

485

Position Analysis of a Pico-Satellite for Optimum Solar Illumination  

NASA Astrophysics Data System (ADS)

This study characterizes the attitude of a satellite in order to obtain the optimum solar illumination on the face of a solar panel. While taking into consideration times of eclipse, a curve for the area exposed to the sun is derived.

Ramirez, F. M.

2014-06-01

486

TWO-LEVEL OPTIMUM DESIGN OF REINFORCED CONCRETE FRAMES WITH INTEGER VARIABLES  

Microsoft Academic Search

In this paper, a highly nonlinear optimum design problem of reinforced concrete frames is treated in two levels corresponding to global constraints and local constraints respectively, with iterations in each level. In the first level, the most flexible structure among those satisfying the global constraints such as displacement constraints, size constraints, etc., is sought under the most unfavourable horizontal loads.

SUN HUANCHUN; CAO ZHENG

1985-01-01

487

Optimum Conditions for Terrestrial Vegetation and Associated Vegetation Feedbacks to the Climate System  

Microsoft Academic Search

Terrestrial vegetation plays an important role in moderating the energy- and water fluxes at the land surface, thereby affecting climate. One of the fundamental features of terrestrial vegetation is its ability to adapt to its climatic environment, thereby maximizing its capacity to perform photosynthesis. Here I apply this concept of optimum adaptation to the parameterization of vegetation in a coupled

A. Kleidon

2004-01-01

488

OPTIMUM UTILIZATION OF GROUND WATER IN KOBO VALLEY, EASTERN AMHARA, ETHIOPIA  

E-print Network

OPTIMUM UTILIZATION OF GROUND WATER IN KOBO VALLEY, EASTERN AMHARA, ETHIOPIA A Thesis Presented and the yield of cereals in the rainy periods. Irrigation from ground water could enable farmers to cultivate more than once a year. Since pumping has an effect on the ground water resources availability

Walter, M.Todd

489

DESIGN OF OPTIMUM CROSS-SECTIONS FOR LOAD-CARRYING MEMBERS USING MULTI-OBJECTIVE  

E-print Network

the capacity, a compressive load carrying strut should have a radius of gyration as large as possibleDESIGN OF OPTIMUM CROSS-SECTIONS FOR LOAD-CARRYING MEMBERS USING MULTI-OBJECTIVE EVOLUTIONARY the induced undesired stresses, a power transmit- ting shaft or a load carrying beam should have its related

Coello, Carlos A. Coello

490

Optimum Source Design for Detection of Heterogeneities in Diffuse Optical Imaging  

E-print Network

analysis by first deriving the discrete source-to-detector map based on the finite-element formulation, Birsen Yazicia, and Kiwoon Kwona aDepartment of Electrical, Computer, and Systems Engineering, Rensselaer detection, diffuse optical tomography, optimum source design 1. INTRODUCTION Diffuse optical imaging

Yazici, Birsen

491

OPTIMUM ALWCATION FOR ESTIMATING AGE COMPOSITION USING AGE-LENGTH KEY  

E-print Network

for a relatively large size, less costly length sample. The second stage involves a stratified random sampling optimum allocation method for age-length keys (ALK) was developed by applying Kimura's Vartot, an error index ofestimated age composition. The method is applied to Pacific cod, sablefish, and walleye pollock

492

An extension of tuning relations after symmetrical optimum method for PI and PID controllers  

Microsoft Academic Search

The paper presents relations for PI and PID controller tuning based on a generalization of the relations after symmetrical optimum (SO) method, introduced by Kessler (Regelungstechnik, 6 (1958), 395400 and 432436), for a class of systems specific to the field of electrical drives. The tuning relations, based on a method developed by Preitl and Precup (Transactions on AC and CS

Stefan Preitl; Radu-Emil Precup

1999-01-01

493

Testing of highly loaded horizontal axis wind turbines designed for optimum performance  

Microsoft Academic Search

The realization of a wind turbine as a source of clean, non-polluting and renewable energy may depend on the optimum design of turbine blades that can operate efficiently under extreme variations in wind conditions. In this paper we provide results of an experimental investigation to examine the effectiveness of a highly loaded theory for the design of a horizontal axis

N. A Ahmed; R. D Archer

2002-01-01

494

A linear quadratic Gaussian with loop transfer recovery proximity operations autopilot for spacecraft. M.S. Thesis - MIT  

NASA Technical Reports Server (NTRS)

An automatic control scheme for spacecraft proximity operations is presented. The controller is capable of holding the vehicle at a prescribed location relative to a target, or maneuvering it to a different relative position using straight line-of-sight translations. The autopilot uses a feedforward loop to initiate and terminate maneuvers, and for operations at nonequilibrium set-po