George Papageorgiou; Keith Glover; Rick Hyde
The H\\u000a ? loop-shaping design procedure (referred to hereafter as LSDP) was used to design fixed gain controllers for the HIRM. It\\u000a was found that a single fixed gain controller designed for the linearisation ini3005, performed adequately over the whole\\u000a flight envelope of the HIRM. As scheduling would most probably be required for a real fighter aircraft with a much
Optimum mask and source patterns to print a given shape
Alan E. Rosenbluth; Scott J. Bukofsky; Michael S. Hibbs; Kafai Lai; Antoinette F. Molless; Rama N. Singh; Alfred K. Wong
2001-01-01
New degrees of freedom can be optimized in mask shapes when the source is also adjustable, because required image symmetries can be provided by the source rather than the collected wavefront. The optimized mask will often consist of novel sets of shapes that are quite different in layout from the target IC patterns. This implies that the optimization algorithm should
Optimum Mask and Source Patterns to Print a Given Shape
Alan E. Rosenbiutha; Scott Bukofsky; Michael Hibbs; Kafai Lai; Antoinette Molless; Rama N. Singh
2001-01-01
ABSTRACT New degrees of freedom can be optimized in mask shapes when the source is also adjustable, because required image symmetries can be provided by the source rather than the collected wavefront. The optimized mask will often consist of novel sets of shapes that are quite different in layout from the target IC patterns. This implies that the optimization algorithm
Optimum mask and source patterns to print a given shape
NASA Astrophysics Data System (ADS)
Rosenbluth, Alan E.; Bukofsky, Scott J.; Hibbs, Michael S.; Lai, Kafai; Molless, Antoinette F.; Singh, Rama N.; Wong, Alfred K. K.
2001-09-01
New degrees of freedom can be optimized in mask shapes when the source is also adjustable, because required image symmetries can be provided by the source rather than the collected wavefront. The optimized mask will often consist of novel sets of shapes that are quite different in layout from the target IC patterns. This implies that the optimization algorithm should have good global convergence properties, since the target patterns may not be a suitable starting solution. We have developed an algorithm that can optimize mask and source without using a starting design. Examples are shown where the process window obtained is between 2 and 6 times larger than that achieved with standard RET methods. The optimized masks require phase shift, but no trim mask is used. Thus far we have only optimized 2D patterns over small fields (periodicities of approximately 1 micrometer or less). We also discuss mask optimization with fixed source, source optimization with fixed mask, and the re-targeting of designs in different mask regions to provide a common exposure level.
Beyond singular values and loop shapes
NASA Technical Reports Server (NTRS)
Stein, G.
1985-01-01
The status of singular value loop-shaping as a design paradigm for multivariable feedback systems is reviewed. It shows that this paradigm is an effective design tool whenever the problem specifications are spacially round. The tool can be arbitrarily conservative, however, when they are not. This happens because singular value conditions for robust performance are not tight (necessary and sufficient) and can severely overstate actual requirements. An alternate paradign is discussed which overcomes these limitations. The alternative includes a more general problem formulation, a new matrix function mu, and tight conditions for both robust stability and robust performance. The state of the art currently permits analysis of feedback systems within this new paradigm. Synthesis remains a subject of research.
Feedback Loops Shape Cellular Signals in Space and Time
NSDL National Science Digital Library
Onn Brandman (University of California-San Francisco and Howard Hughes Medical Institute; Department of Cellular and Molecular Pharmacology)
2008-10-17
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.
Measuring Shape-Dependent Looping Probability of DNA
Le, Tung T.; Kim, Harold D.
2013-01-01
Recently, several studies have shown that short doubled-stranded DNA (dsDNA) loops more readily than the wormlike chain model predicts. In most of these experiments, the intrinsic bendedness of dsDNA, which in theory can dramatically influence looping dynamics, was either avoided or unaccounted for. To investigate the effect of the shape of dsDNA on looping dynamics, we characterized the shapes of several synthetic dsDNA molecules of equal length but different sequences using gel electrophoresis. We then measured their looping rates using a FRET (Förster resonance energy transfer)-based assay and extracted the looping probability density known as the J factor (jM). We also used, for comparison, several dinucleotide angular parameter sets derived from the observed electrophoretic mobility to compute the jM predicted by the wormlike chain model. Although we found a strong correlation between curvature and jM, the measured jM was higher than most dinucleotide model predictions. This result suggests that it is difficult to reconcile the looping probability with the observed gel mobility within the wormlike chain model and underscores the importance of determining the intrinsic shape of dsDNA for proper theoretical analysis. PMID:23663850
NASA Astrophysics Data System (ADS)
Jeon, W. H.; Kim, N.; Lee, J. Y.
2014-12-01
This study aims to evaluate the influence of open loop ground source heat pump systems operation on hydrological conditions of aquifer. Test bed is located in Chuncheon, Korea. The step drawdown test was conducted in five stages for 300 minutes. The variation of groundwater levels by open loop ground source heat pump systems operation was estimated using Visual MODFLOW. Transmissivity ranged from 2.02×10-4 to 9.36×10-4, and storage coefficient ranged from 0.00067 to 0.021. The amount of optimum bleeding was calculated to be 240 m3/day. When bleeding will be 50, 90, 240 and 450 m3/day for 5 years, groundwater levels may decrease 1.84, 3.31, 8.89 and 17.0 m, respectively. If the amount of bleeding is 50 m3/day, the influence of bleeding will not reach the boundary regions of the Soyang River after 5 years. Regarding the open loop ground source heat pump system installed at the test bed, the amount of optimum bleeding in accordance with the stand are proposed by the government is 90 m3/day, which is 20% of the 450 m3/day circulation quantity of the system. However, if continuous bleeding of more than 90 m3/day occurs, then the radius of influence is expected to reach the boundary regions of the Soyang River after 5 years. These results indicate that amount of optimum bleeding differ in each open loop ground soured heat pump system. Therefore, the debate for the amount of optimum bleeding in open loop ground source heat pump systems is demanded. This work is supported by the Energy Efficiency and Resources of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy (No.20123040110010).
Spectrum shape compression and pedestal elimination employing a Sagnac loop
NASA Astrophysics Data System (ADS)
Jintao, Tao; Hongjun, Liu; Cunxiao, Gao; Wei, Zhao; Yishan, Wang; Guofu, Chen
2009-01-01
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.
Resonantly damped oscillations of elliptically shaped stratified emerging coronal loops
NASA Astrophysics Data System (ADS)
Karami, K.; Amiri, S.; Bahari, K.; Ebrahimi, Z.
2013-09-01
The effects of both elliptical shape and stage of emergence of the coronal loop on the resonant absorption of standing kink oscillations are studied. To do so, a typical coronal loop is modeled as a zero-beta longitudinally stratified cylindrical magnetic flux tube. We developed the connection formulae for the resonant absorption of standing transversal oscillations of a coronal loop with an elliptical shape, at various stages of its emergence. Using the connection formulae, the dispersion relation is derived and solved numerically to obtain the frequencies and damping rates of the fundamental and first-overtone kink modes. Our numerical results show that both the elliptical shape and stage of emergence of the loop alter the frequencies and damping rates of the tube as well as the ratio of frequencies of the fundamental and its first-overtone modes. However, the ratio of the oscillation frequency to the damping rate is not affected by the tube shape and stage of its emergence and also is independent of the density stratification parameter.
Resonantly damped oscillations of elliptically shaped stratified emerging coronal loops
Karami, K; Bahari, K; Ebrahimi, Z
2013-01-01
The effects of both elliptical shape and stage of emergence of the coronal loop on the resonant absorption of standing kink oscillations are studied. To do so, a typical coronal loop is modeled as a zero-beta longitudinally stratified cylindrical magnetic flux tube. We developed the connection formulae for the resonant absorption of standing transversal oscillations of a coronal loop with an elliptical shape, at various stages of its emergence. Using the connection formulae, the dispersion relation is derived and solved numerically to obtain the frequencies and damping rates of the fundamental and first-overtone kink modes. Our numerical results show that both the elliptical shape and stage of emergence of the loop alter the frequencies and damping rates of the tube as well as the ratio of frequencies of the fundamental and its first-overtone modes. However, the ratio of the oscillation frequency to the damping rate is not affected by the tube shape and stage of its emergence and also is independent of the de...
{alpha}-Shaped DNA loops induced by MutS
Jia Yanxia [National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China); State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071 (China); Shenyang Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110015 (China); Graduate School, Chinese Academy of Sciences, Beijing (China); Bi Lijun; Li Feng; Chen Yuanyuan [National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China); Zhang Chenggang [Shenyang Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110015 (China); Zhang Xianen [State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071 (China)], E-mail: Zhangxe@sun5.ibp.ac.cn
2008-08-08
DNA mismatch repair (MMR) is critical for the maintenance of genomic stability. MMR is initiated by recognition of DNA mismatches by the protein, MutS, which subsequently recruits downstream repair factors. To better understand the mechanism by which MutS identifies and specifically binds mismatched basepairs embedded in random DNA sequences, we monitored the interaction between MutS and DNA substrates using atomic force microscopy (AFM). An {alpha}-shaped DNA loop formed by the interaction between MutS and DNA, which was independent of whether or not a mismatch was present in the DNA substrate. These data indicate that MutS associates with DNA non-specifically and forms an {alpha}-loop interaction with the DNA substrate. In this conformation, MutS is able to scan two arms of DNA simultaneously for each MutS dimer formed.
Why Are Some Hysteresis Loops Shaped Like a Butterfly? Bojana Drincic a
Tan, Xiaobo
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
NASA Astrophysics Data System (ADS)
Luo, Quantian; Tong, Liyong
2007-10-01
This paper presents a segment based sequential least squares algorithm with optimum energy control for tracking the dynamic shapes of piezoelectric smart structures. In this algorithm, integration of the square difference between the desired and achieved dynamic shapes over a time period is employed as an error function. The total electrical energy consumption of all actuators is used as the other control target. Two control schemes are studied: (a) minimization of the square error over a time period with energy constraint and (b) minimization of control energy with specified square error constraint. The Lagrange multiplier technique is used to consider the constraint, in which the properties of the characteristic matrix and polynomials of the Lagrange multiplier are analysed. Based on the present analysis, a simple and efficient algorithm is proposed; the relationship between permissible energy constraint and achievable minimum square error is investigated. Numerical results are presented for tracking twisting shape variations of a smart plate. Optimum energy control for reducing conflicting effects of the applied actuation voltages is also discussed.
On the optimum shape of thin adhesive strips for various peeling directions
: computational shape optimization, adhesive tapes, cohesive zone models, peeling angle, gecko adhesion 1. The anisotropic attachment and detachment behavior of the microstructures underneath gecko toes, for instance, has
Practical Loop-Shaping Design of Feedback Control Systems
NASA Technical Reports Server (NTRS)
Kopasakis, George
2010-01-01
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.
NASA Astrophysics Data System (ADS)
Ozen, Murat; Guler, Murat
2014-02-01
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.
Role of measurement voltage on hysteresis loop shape in Piezoresponse Force Microscopy
Kim, Yunseok [ORNL; Yang, J.-C. [University of California, Berkeley; Chu, Ying Hao [National Chiao Tung University, Hsinchu, Taiwan; Yu, Pu [University of California, Berkeley; Lu, X. [Xidian University, China; Jesse, Stephen [ORNL; Kalinin, Sergei V [ORNL
2012-01-01
The dependence of on-field and off-field hysteresis loop shape in Piezoresponse Force Microscopy (PFM) on driving voltage, Vac, is explored. A nontrivial dependence of hysteresis loop parameters on measurement conditions is observed. The strategies to distinguish between paraelectric and ferroelectric states with small coercive bias and separate reversible hysteretic and non-hysteretic behaviors are suggested. Generally, measurement of loop evolution with Vac is a necessary step to establish the veracity of PFM hysteresis measurements.
Precise open-loop control of MEMS deformable mirror shape Thomas Bifano a,c
Precise open-loop control of MEMS deformable mirror shape Thomas Bifano a,c , Jason Stewart b error. Keywords: MEMS, adaptive optics, open-loop control, deformable mirror 1. INTRODUCTION In some correspondingly more and faster actuators. DMs made using microelectromechanical systems (MEMS) technology have
Green Communications by Demand Shaping and User-in-the-Loop Tariff-based Control
Yanikomeroglu, Halim
Green Communications by Demand Shaping and User-in-the-Loop Tariff-based Control Rainer Schoenen1 at a fast pace. Flat rates or almost flat utility tariffs have spoiled users and established high user of overprovisioning. New tariffs are required that are tailored to the major QoS classes and help to shape demand
Domain Nucleation and Hysteresis Loop Shape in Piezoresponse Force Spectroscopy
Morozovska, A. N. [National Academy of Science of Ukraine, Kiev, Ukraine; Eliseev, E. A. [National Academy of Science of Ukraine, Kiev, Ukraine; Kalinin, Sergei V [ORNL
2006-01-01
Electromechanical hysteresis loop measurements in piezoresponse force microscopy (PFM) [piezoresponse force spectroscopy (PFS)] have emerged as a powerful technique for probing ferroelectric switching behavior on the nanoscale. Interpretation of PFS data requires the relationship between the domain parameters and PFM signal to be established. Here, the authors analyze the switching process using modified point charge model. The charge parameters are selected to reproduce tip-induced surface potential and tip radius of curvature. The relationship between geometric parameters of semiellipsoidal domain and PFM signal is derived using linear Green's function theory. The role of domain nucleation on hysteresis loop is established.
Loop shaping issues in hard disk drive servo system design
Alessandro Beghi; Roberto Oboe; Paolo Capretta; Francesco Chrappan Soldavini
2001-01-01
In this paper, the design of hard disk drive (HDD) servo systems based on state-space techniques is considered. In particular, we analyze the performances of discrete-time controllers obtained by means of LQG optimal control theory. The key control design issue we address is related to the need of achieving sufficiently high close-loop bandwidth while granting adequate disturbance rejection in the
Interpolating gain-scheduled H? loop shaping design for high speed ball screw feed drives.
Dong, Liang; Tang, WenCheng; Bao, DaFei
2015-03-01
This paper presents a method to design servo controllers for flexible ball screw drives with time-varying dynamics, which are mainly due to the time-varying table position and the workpiece mass. A gain-scheduled H? loop shaping controller is designed to achieve high tracking performance against the dynamic variations. H? loop shaping design procedure incorporates open loop shaping by a set of compensators to obtain performance/robust stability tradeoffs. The interpolating gain-scheduled controller is obtained by interpolating the state space model of the linear time-invariant (LTI) controllers estimated for fixed values of the scheduling parameters and a linear least squares problem can be solved. The proposed controller has been compared with P/PI with velocity and acceleration feedforward and adaptive backstepping sliding mode control experimentally. The experimental results indicate that the tracking performance has been improved and the robustness for time-varying dynamics has been achieved with the proposed scheme. PMID:25592980
Elena Grassi; Kostas Tsakalis
2000-01-01
A frequency loop-shaping technique for tuning proportional-integral-derivative controllers is applied to temperature control of a three-zone industrial diffusion furnace used in semiconductor manufacturing. In this tuning method the controller parameters are tuned so as to minimize the difference between the actual and a target loop transfer function, in an L? sense. The problem is formulated in the frequency domain as
NASA Astrophysics Data System (ADS)
Wei, Tao; Mu, Shengjing; Nakano, Aiichiro; Shing, Katherine
2009-05-01
Atomistic simulation of protein adsorption on a solid surface in aqueous environment is computationally demanding, therefore the determination of preferred protein orientations on the solid surface usually serves as an initial step in simulation studies. We have developed a hybrid multi-loop genetic-algorithm/simplex/spatial-grid method to search for low adsorption-energy orientations of a protein molecule on a solid surface. In this method, the surface and the protein molecule are treated as rigid bodies, whereas the bulk fluid is represented by spatial grids. For each grid point, an effective interaction region in the surface is defined by a cutoff distance, and the possible interaction energy between an atom at the grid point and the surface is calculated and recorded in a database. In searching for the optimum position and orientation, the protein molecule is translated and rotated as a rigid body with the configuration obtained from a previous Molecular Dynamic simulation. The orientation-dependent protein-surface interaction energy is obtained using the generated database of grid energies. The hybrid search procedure consists of two interlinked loops. In the first loop A, a genetic algorithm (GA) is applied to identify promising regions for the global energy minimum and a local optimizer with the derivative-free Nelder-Mead simplex method is used to search for the lowest-energy orientation within the identified regions. In the second loop B, a new population for GA is generated and competitive solution from loop A is improved. Switching between the two loops is adaptively controlled by the use of similarity analysis. We test the method for lysozyme adsorption on a hydrophobic hydrogen-terminated silicon (110) surface in implicit water (i.e., a continuum distance-dependent dielectric constant). The results show that the hybrid search method has faster convergence and better solution accuracy compared with the conventional genetic algorithm.
Loop shaping H? design applied to the steam generator level control in EDF nuclear power plants
P. Ambos; G. Duc; C. M. Falinower
1996-01-01
The objective of this paper is to design a controller for a pressurized water reactor steam generator using model based control techniques. The loop-shaping design procedure of McFarlane and Glover (1992) is used together with the gap metric of Vinnicombe (1992), the latter allowing one to a priori insure the robust stability of several linearized models. Namely the gap metric
Loop-shaping Design with Constant Magnitude Loci in Control Education*
Regruto, Diego
Loop-shaping Design with Constant Magnitude Loci in Control Education* V. CERONE, M. CANALE and D constant magnitude loci of the sensitivity function along with the well-assessed constant magnitude loci of the constant magnitude loci MT of j T j3 j (also referred to as the Hall chart, [2]) and constant magnitude
Inequalities for Wilson loops, cusp singularities, area law and shape of a drum
P. V. Pobylitsa
2007-02-15
Inequalities are derived for Wilson loops generalizing the well-known Bachas inequality for rectangular contours. The inequalities are compatible with the area law for large contours. The Polyakov cusp anomalous dimension of Wilson lines (playing an important role in QCD applications to hard processes) has a convex angular dependence. This convexity is crucial for the consistency of the inequalities with renormalization. Some parallel properties can be found in the string theory. The Kac-Ray cusp term from the "shape of a drum" problem has the same angular convexity property and plays the role of the cusp anomalous dimension in the effective string model for Wilson loops studied by Luescher, Symanzik and Weisz (LSW). Using heuristic arguments based on the LSW model, one can find an interesting connection between the inequalities for Wilson loops and inequalities for determinants of two-dimensional Laplacians with Dirichlet boundary conditions on the closed contours associated with Wilson loops.
Inequalities for Wilson loops, cusp singularities, area law and shape of a drum
Pobylitsa, P V
2007-01-01
Inequalities are derived for Wilson loops generalizing the well-known Bachas inequality for rectangular contours. The inequalities are compatible with the area law for large contours. The Polyakov cusp anomalous dimension of Wilson lines (playing an important role in QCD applications to hard processes) has a convex angular dependence. This convexity is crucial for the consistency of the inequalities with renormalization. Some parallel properties can be found in the string theory. The Kac-Ray cusp term from the "shape of a drum" problem has the same angular convexity property and plays the role of the cusp anomalous dimension in the effective string model for Wilson loops studied by Luescher, Symanzik and Weisz (LSW). Using heuristic arguments based on the LSW model, one can find an interesting connection between the inequalities for Wilson loops and inequalities for determinants of two-dimensional Laplacians with Dirichlet boundary conditions on the closed contours associated with Wilson loops.
Segmented shape memory alloy actuators using hysteresis loop control
NASA Astrophysics Data System (ADS)
Selden, Brian; Cho, Kyujin; Asada, H. Harry
2006-04-01
A new approach to the design and control of shape memory alloy (SMA) actuators is presented. SMA wires are divided into many segments and their thermal states are controlled individually as a group of finite state machines. Instead of driving a current to the entire SMA wire and controlling the wire length based on the analog strain-temperature characteristics, the new method controls the binary state (hot or cold) of individual segments and thereby the total displacement is proportional to the length of the heated segments, i.e. austenite phase. Although the thermomechanical properties of SMA are highly nonlinear and uncertain with a prominent hysteresis, segmented binary control is robust and stable, providing characteristics similar to a stepping motor. However, the heating and cooling of each segment to its bi-stable states entail longer time and larger energy for transition. In this paper, an efficient method for improving the speed of response and power consumption is developed by exploiting the inherent hysteresis of SMA. Instead of keeping the extreme temperatures continuously, the temperatures return to intermediate 'hold' temperatures closer to room temperature but sufficient to keep constant phase. Coordination of the multitude of segments having independent thermal states allows for faster response with little latency time even for thick SMA wires. Based on stress dependent thermomechanical characteristics, the hold temperature satisfying a given stress margin is obtained. The new control method is implemented using the Peltier effect thermoelectric devices for selective segment-by-segment heating and cooling. Experiments demonstrate the effectiveness of the proposed method.
Looped star polymers show conformational transition from spherical to flat toroidal shapes.
Reiss, Pascal; Fritsche, Miriam; Heermann, Dieter W
2011-11-01
Inspired by the topological organization of the circular Escherichia coli chromosome, which is compacted by separate domains, we study a polymer architecture consisting of a central ring to which either looped or linear side chains are grafted. A shape change from a spherical to a toroidal organization takes place as soon as the inner ring becomes large enough for the attached arms to fit within its circumference. Building up a torus, the system flattens, depending on the effective bending rigidity of the chain induced by entropic repulsion of the attached loops and, to a lesser extent, linear arms. Our results suggest that the natural formation of a toroidal structure with a decreased amount of writhe induced by a specific underlying topology could be one driving force, among others, that nature exploits to ensure proper packaging of the genetic material within a rod-shaped, bacterial envelope. PMID:22181447
Shaping of Looped Miniaturized Chalcogenide Fiber Sensing Heads for Mid-Infrared Sensing
Houizot, Patrick; Anne, Marie-Laure; Boussard-Plédel, Catherine; Loréal, Olivier; Tariel, Hugues; Lucas, Jacques; Bureau, Bruno
2014-01-01
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
NASA Technical Reports Server (NTRS)
Fox, S. R.; Smetana, F. O.
1980-01-01
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.
NASA Technical Reports Server (NTRS)
Fox, S. R.; Smetana, F. O.
1980-01-01
The listings, user's instructions, sample inputs, and sample outputs of two computer programs which are especially useful in obtaining an approximate solution of the viscous flow over an arbitrary nonlifting three dimensional body are provided. The first program performs a potential flow solution by a well known panel method and readjusts this initial solution to account for the effects of the boundary layer displacement thickness, a nonuniform but unidirectional onset flow field, and the presence of air intakes and exhausts. The second program is effectually a geometry package which allows the user to change or refine the shape of a body to satisfy particular needs without a significant amount of human intervention. An effort to reduce the cruise drag of light aircraft through an analytical study of the contributions to the drag arising from the engine cowl shape and the foward fuselage area and also that resulting from the cooling air mass flowing through intake and exhaust sites on the nacelle is presented. The programs may be effectively used to determine the appropriate body modifications or flow port locations to reduce the cruise drag as well as to provide sufficient air flow for cooling the engine.
Chunling Du; Shuzhi Sam Ge; F. L. Lewis; Jingliang Zhang
2007-01-01
This paper focuses on compensation for external vibration effect on the positioning accuracy of hard disk drives. A feedforward controller is designed to attenuate the effect with the aid of a sensor to detect external vibrations. Loop shaping in frequency domain and H? method in state space are used to design the feedforward controller. The application results in a 1.8-inch
NASA Astrophysics Data System (ADS)
Piccirillo, V.; Tusset, A. M.; Balthazar, J. M.; Bernardini, D.; Rega, G.
2014-12-01
The dynamical response of systems with shape memory alloy (SMA) presents a different behavior due to their nonlinear characteristic. SMA nonlinear response is associated with adaptive dissipation related to their hysteretic behavior. This paper discusses the nonlinear responses of shape-memory non-ideal oscillators, based on a thermomechanical consistent model with four state variables. Two cases are investigating, namely, the case when SMA presents a large hysteresis loop and another one with less hysteresis. Computer simulations are carried out via a numerical approach showing qualitative results concerned with regular and non-regular motions.
A novel device allowing for movement and trapping of particles within loop-shaped channels
NASA Astrophysics Data System (ADS)
Hahn, P.; Dual, J.
2012-05-01
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.
Tao Wei; Shengjing Mu; Aiichiro Nakano; Katherine Shing
2009-01-01
Atomistic simulation of protein adsorption on a solid surface in aqueous environment is computationally demanding, therefore the determination of preferred protein orientations on the solid surface usually serves as an initial step in simulation studies. We have developed a hybrid multi-loop genetic-algorithm\\/simplex\\/spatial-grid method to search for low adsorption-energy orientations of a protein molecule on a solid surface. In this method,
Son, Byung-Chul; Kim, Deog-Ryeong
2015-01-01
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
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
NASA Technical Reports Server (NTRS)
Connolly, Joseph W.; Kopasakis, George
2010-01-01
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.
Asymmetrically shaped hysteresis loop in exchange-biased FeNi/FeMn film
NASA Astrophysics Data System (ADS)
Gnatchenko, S. L.; Merenkov, D. N.; Bludov, A. N.; Pishko, V. V.; Shakhayeva, Yu. A.; Baran, M.; Szymczak, R.; Novosad, V. A.
2006-12-01
The magnetization reversal of the bilayer polycrystalline FeNi(50 Å)/FeMn(50 Å) film sputtered in a magnetic field has been studied by magnetic and magneto-optical techniques. The external magnetic fields were applied along the easy or hard magnetization axis of the ferromagnetic permalloy layer. The asymmetry of hysteresis loop has been found. Appreciable asymmetry and the exchange bias were observed only in the field applied along the easy axis. The specific features of magnetization reversal were explained within the phenomenological model that involves high-order exchange anisotropy and misalignment of the easy axes of the antiferromagnetic and ferromagnetic layers. It has been shown that the film can exist in one of three equilibrium magnetic states in the field applied along the easy axis. The transitions between these states occur as first-order phase transitions. The observed hysteresis loop asymmetry is related to the existence of the metastable state.
Asymmetrically shaped hysteresis loop in exchange-biased FeNi\\/FeMn film
S. L. Gnatchenko; D. N. Merenkov; A. N. Bludov; V. V. Pishko; Yu. A. Shakhayeva; M. Baran; R. Szymczak; V. A. Novosad
2006-01-01
The magnetization reversal of the bilayer polycrystalline FeNi(50Å)\\/FeMn(50Å) film sputtered in a magnetic field has been studied by magnetic and magneto-optical techniques. The external magnetic fields were applied along the easy or hard magnetization axis of the ferromagnetic permalloy layer. The asymmetry of hysteresis loop has been found. Appreciable asymmetry and the exchange bias were observed only in the field
Kotur, Marija; Weinacht, Thomas; Pearson, Brett J; Matsika, Spiridoula
2009-04-01
We demonstrate the use of shaped ultrafast laser pulses in the deep ultraviolet to control the ring opening isomerization of 1,3-cyclohexadiene to form 1,3,5-hexatriene. The experiments are performed with a gas phase sample and the isomerization yield is probed with dissociative ionization driven by a time-delayed, intense infrared laser pulse. Differences in the electronic structure of the ions for the two isomers, as shown by ab initio calculations, result in very different fragmentation products following strong-field ionization. We find that a shaped pulse yields a approximately 37% increase in the isomerization over an unshaped laser pulse. PMID:19355736
NSDL National Science Digital Library
Ms. Fletcher
2007-10-23
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 ...
Optimum and near-optimum blade configurations for high speed wind turbines
D. E. Cromack; P. L. Lefebvre
1977-01-01
Presented are the results of a parametric study showing comparisons for high speed windmill rotors of 2, 3, and 4 blades and of aerodynamically optimum, near optimum, and constant chord zero-twist blade shapes. Near optimum blades consisting of linear-taper and linear-twist represent a significant degree of simplification for manufacture. Results of this study indicate that only a small performance loss
NSDL National Science Digital Library
Miss Stringfield
2008-11-17
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. ...
Michail, Konstantinos; Zolotas, Argyrios C; Goodall, Roger M
2014-01-01
This paper presents a systematic design framework for selecting the sensors in an optimised manner, simultaneously satisfying a set of given complex system control requirements, i.e. optimum and robust performance as well as fault tolerant control for high integrity systems. It is worth noting that optimum sensor selection in control system design is often a non-trivial task. Among all candidate sensor sets, the algorithm explores and separately optimises system performance with all the feasible sensor sets in order to identify fallback options under single or multiple sensor faults. The proposed approach combines modern robust control design, fault tolerant control, multiobjective optimisation and Monte Carlo techniques. Without loss of generality, it's efficacy is tested on an electromagnetic suspension system via appropriate realistic simulations. PMID:24041402
Interactions of Cations with RNA Loop-Loop Complexes
Singh, Abhishek; Sethaphong, Latsavongsakda; Yingling, Yaroslava G.
2011-01-01
RNA loop-loop interactions are essential in many biological processes, including initiation of RNA folding into complex tertiary shapes, promotion of dimerization, and viral replication. In this article, we examine interactions of metal ions with five RNA loop-loop complexes of unique biological significance using explicit-solvent molecular-dynamics simulations. These simulations revealed the presence of solvent-accessible tunnels through the major groove of loop-loop interactions that attract and retain cations. Ion dynamics inside these loop-loop complexes were distinctly different from the dynamics of the counterion cloud surrounding RNA and depend on the number of basepairs between loops, purine sequence symmetry, and presence of unpaired nucleotides. The cationic uptake by kissing loops depends on the number of basepairs between loops. It is interesting that loop-loop complexes with similar functionality showed similarities in cation dynamics despite differences in sequence and loop size. PMID:21806941
Boyer, M. D. [PPPL; Andre, R. [PPPL; Gates, David A. [PPPL; Gerhardt, S. [PPPL; Goumiri, I. R. [Princeton University; Menard, Jon [PPPL
2014-08-01
The high-performance operational goals of NSTX-U will require development of advanced feedback control algorithms, including control of ßN and the safety factor profile. In this work, a novel approach to simultaneously controlling #12;ßN and the value of the safety factor on the magnetic axis, q0, through manipulation of the plasma boundary shape and total beam power, is proposed. Simulations of the proposed scheme show promising results and motivate future experimental implementation and eventual integration into a more complex current profile control scheme planned to include actuation of individual beam powers, density, and loop voltage. As part of this work, a flexible framework for closed loop simulations within the high-fidelity code TRANSP was developed. The framework, used here to identify control-design-oriented models and to tune and test the proposed controller, exploits many of the predictive capabilities of TRANSP and provides a means for performing control calculations based on user-supplied data (controller matrices, target waveforms, etc.). The flexible framework should enable high-fidelity testing of a variety of control algorithms, thereby reducing the amount of expensive experimental time needed to implement new control algorithms on NSTX-U and other devices.
NSDL National Science Digital Library
Ms. Johnson
2008-04-30
Shapes are awesome! Can you Assemble the Square? Play this game and find out! Slide, flip, and rotate the shapes in RoboPacker! Practice your geometry vocabulary and use the Flash Cards for Geometry!! ...
JOINT PERFORMANCE Guide for Optimum
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
FISHER'S GEOMETRIC MODEL WITH A MOVING OPTIMUM
Matuszewski, Sebastian; Hermisson, Joachim; Kopp, Michael
2014-01-01
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
Logic circuit exhibits optimum performance
NASA Technical Reports Server (NTRS)
Husson, C.
1965-01-01
Performance of circuits are compared to determine the optimum circuit configuration for implementation into microelectronic functions. Comparison is made in terms of power drain, propagation time, and component variations with temperature and load.
Optimum balancing for flexible rotor
Fu, Her James
1975-01-01
OPTIMUM BALANCING FOR FLEXIBLE ROTOR A Thesis by Her"Fu Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER QF SCIENCE December 1975 Major Subject: Mechanical... Engineering OPTIMUM BALANCING FOR FLEXIBLE ROTOR A Thesis by Her Fu Approved as to style and content by: , ' '/ / I (. '~. '. . . (''':: '~ 9, ' ', fr')" ? '? , ' (Chairman of Committee) (Head of Department) (Member) (Member) De cemb er 19 75...
Towards optimum demodulation of bandwidth-limited and low SNR square-wave subcarrier signals
NASA Technical Reports Server (NTRS)
Feria, Y.; Hurd, W.
1995-01-01
The optimum phase detector is presented for tracking square-wave subcarriers that have been bandwidth limited to a finite number of harmonics. The phase detector is optimum in the sense that the loop signal-to-noise ratio (SNR) is maximized and, hence, the rms phase tracking error is minimized. The optimum phase detector is easy to implement and achieves substantial improvement. Also presented are the optimum weights to combine the signals demodulated from each of the harmonics. The optimum weighting provides SNR improvement of 0.1 to 0.15 dB when the subcarrier loop SNR is low (15 dB) and the number of harmonics is high (8 to 16).
Optimum Aerodynamic Design using the Navier--Stokes Equations
Pierce, Niles A.
Optimum Aerodynamic Design using the Navier--Stokes Equations A. JAMESON \\Lambda ; N.A. PIERCE y factors such as aerodynamic effi ciency, structural weight, stability and control, and the volume the disciplines. The development of accurate and efficient methods for aerodynamic shape optimization represents
Kim, Jung Hyup; Rothrock, Ling; Laberge, Jason
2014-05-01
This paper provides a case study of Signal Detection Theory (SDT) as applied to a continuous monitoring dual-task environment. Specifically, SDT was used to evaluate the independent contributions of sensitivity and bias to different qualitative gauges used in process control. To assess detection performance in monitoring the gauges, we developed a Time Window-based Human-In-The-Loop (TWHITL) simulation bed. Through this test bed, we were able to generate a display similar to those monitored by console operators in oil and gas refinery plants. By using SDT and TWHITL, we evaluated the sensitivity, operator bias, and response time of flow, level, pressure, and temperature gauge shapes developed by Abnormal Situation Management(®) (ASM(®)) Consortium (www.asmconsortium.org). Our findings suggest that display density influences the effectiveness of participants in detecting abnormal shapes. Furthermore, results suggest that some shapes elicit better detection performance than others. PMID:24079651
Optimum designs for superpressure balloons
NASA Astrophysics Data System (ADS)
Smith, M. S.; Rainwater, E. L.
2004-01-01
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.
Malanushenko, A.; Longcope, D. W.; McKenzie, D. E. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States)
2009-12-20
Nonlinear force-free fields are the most general case of force-free fields, but the hardest to model as well. There are numerous methods of computing such fields by extrapolating vector magnetograms from the photosphere, but very few attempts have so far made quantitative use of coronal morphology. We present a method to make such quantitative use of X-ray and EUV images of coronal loops. Each individual loop is fit to a field line of a linear force-free field, allowing the estimation of the field line's twist, three-dimensional geometry, and the field strength along it. We assess the validity of such a reconstruction since the actual corona is probably not a linear force-free field, and that the superposition of linear force-free fields is generally not itself a force-free field. To do so, we perform a series of tests on nonlinear force-free fields, described in Low and Lou. For model loops we project field lines onto the photosphere. We compare several results of the method with the original field, in particular the three-dimensional loop shapes, local twist (coronal alpha), distribution of twist in the model photosphere, and strength of the magnetic field. We find that (1) for these trial fields, the method reconstructs twist with a mean absolute deviation of at most 15% of the range of photospheric twist, (2) heights of the loops are reconstructed with a mean absolute deviation of at most 5% of the range of trial heights, and (3) the magnitude of non-potential contribution to a photospheric field is reconstructed with a mean absolute deviation of at most 10% of the maximal value.
Optimum shapes for lightweighted mirrors. [of astronomical telescopes
NASA Technical Reports Server (NTRS)
Vukobratovich, D.; Iraninejad, B.; Richard, R. M.; Hansen, Q. M.; Melugin, R.
1982-01-01
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.
B. Bruegmann
1993-12-02
The loop representation plays an important role in canonical quantum gravity because loop variables allow a natural treatment of the constraints. In these lectures we give an elementary introduction to (i) the relevant history of loops in knot theory and gauge theory, (ii) the loop representation of Maxwell theory, and (iii) the loop representation of canonical quantum gravity. (Based on lectures given at the 117. Heraeus Seminar, Bad Honnef, Sept. 1993)
Optimum reentry trajectories of a lifting vehicle
NASA Technical Reports Server (NTRS)
Chern, J. S.; Vinh, N. X.
1980-01-01
Research results are presented of an investigation of the optimum maneuvers of advanced shuttle type spacecraft during reentry. The equations are formulated by means of modified Chapman variables resulting in a general set of equations for flight analysis which are exact for reentry and for flight in a vacuum. Four planar flight typical optimum manuevers are investigated. For three-dimensional flight the optimum trajectory for maximum cross range is discussed in detail. Techniques for calculating reentry footprints are presented.
Optimum blank design in sheet metal forming by the deformation path iteration method
S. H. Park; J. W. Yoon; D. Y. Yang; Y. H. Kim
1999-01-01
Optimum blank design methods have been introduced by many researchers to reduce development cost and time in the sheet metal-forming process. Direct inverse design method such as Ideal Forming (Chang and Richmond, Int J Mech Sci 1992; 34(7) and (8): 575–91 and 617–33) [7,8] for optimum blank shape could play an important role to give a basic idea to designer
Concepts for generating optimum vertical flight profiles
NASA Technical Reports Server (NTRS)
Sorensen, J. A.
1979-01-01
Algorithms for generating optimum vertical profiles are derived and examined. These algorithms form the basis for the design of onboard flight management concepts. The variations in the optimum vertical profiles (resulting from these concepts) due to variations in wind, takeoff weight, and range-to-destination are presented. Further considerations for mechanizing two different onboard methods of computing near-optimum flight profiles are then outlined. Finally, the results are summarized, and recommendations are made for further work. Technical details of optimum trajectory design, steering requirements for following these trajectories, and off-line computer programs for testing the concepts are included.
The optimum hypersonic wind tunnel
NASA Technical Reports Server (NTRS)
Trimmer, L. L.; Cary, A., Jr.; Voisinet, R. L. P.
1986-01-01
The capabilities of existing hypersonic wind tunnels in the U.S. are assessed to form a basis for recommendations for a new, costly facility which would provide data for modeling the hypervelocity aerodynamics envisioned for the new generation of aerospace vehicles now undergoing early studies. Attention is given to the regimes, both entry and aerodynamic, which the new vehicles will encounter, and the shortcomings of data generated for the Orbiter before flight are discussed. The features of foreign-gas, impulse, aeroballistic range, arc-heated and combustion-heated facilities are examined, noting that in any hypersonic wind tunnel the flow must be preheated to prevent liquefaction upon expansion in the test channel. The limitations of the existing facilities and the identification of the regimes which must be studied lead to a description of the characteristics of an optimum hypersonic wind tunnel, including the operations and productivity, the instrumentation, the nozzle design and the flow quality. Three different design approaches are described, each costing at least $100 million to achieve workability.
Optimum hypersonic airfoil with power law shock waves
Wagner, B.A.
1990-01-01
In the present paper the flow field over a class of two-dimensional lifting surfaces is examined from the viewpoint of inviscid, hypersonic small-disturbance theory (HSDT). It is well known that a flow field in which the shock shape S(x) is similar to the body shape F(x) is only possible for F(x) = x{sup k} and the freestream Mach number M{sub {infinity}} = {infinity}. This self-similar flow has been studied for several decades as it represents one of the few existing exact solutions of the equations of HSDT. Detailed discussions are found for example in papers by Cole, Mirels, Chernyi and Gersten and Nicolai but they are limited to convex body shapes, that is, k {le} 1. The only study of concave body shapes was attempted by Sullivan where only special cases were considered. The method used here shows that similarity also exists for concave shapes and a complete solution of the flow field for any k > 2/3 is given. The effect of varying k on C{sub L}{sup 3/2}/C{sub D} is then determined and an optimum shape is found. Furthermore, a wider class of lifting surfaces is constructed using the streamlines of the basic flow field and analysed with respect to the effect on C{sub L}{sup 3/2}/C{sub D}. 9 refs., 3 figs.
Bayesian Optimum Planning for Accelerated Life Tests
Yao Zhang; William Q. Meeker
This paper describes a Bayesian method for optimum accelerated life test planning with one accelerating variable, when the acceleration model is linear in the parame- ters, based on censored data from a log-location-scale distribution. We use a Bayesian criterion based on estimation precision of a distribution quantile at a specified use condition and use this criterion to find optimum test
Efficient aerodynamic shape optimization in MDO context
Antonio Fazzolari; Nicolas R. Gauger; Joel Brezillon
2007-01-01
Multidisciplinary analysis is necessary to reach physically meaningful optimum designs. For aero-structural shape optimization this means coupling two disciplines—aerodynamics and structural mechanics. In this paper, the sensitivity evaluation for aerodynamic shape optimization is considered, while taking into account the static aeroelastic effects introduced by the variations in the aerodynamic forces, which are associated with changes in the aerodynamic shape. Due
EFP05 -OPTIPOLYGEN Optimum integration of
EFP05 - OPTIPOLYGEN Optimum integration of polygeneration in the food industry FORCE Technology..........................................................................12 4.6 WP 6 - Training materials for polygeneration the potential of utilising and im- plementing polygeneration technologies in the food and drink industry. Due
Optimum Polarization for Foliage Camouflaged Target Discrimination
Sarabandi, Kamal
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
Neoclassical formulations of optimum population theory
Davis, Glenn Anthony
1971-01-01
NEOCLASSICAL FORMULATIONS OF OPTIMUM POPULATION THEORY A Thesis by GLENN ANTHONY DAVIS Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE August 1971... Major Subject: Economics NEOCLASSICAL FORMULATIONS OF OPTIMUM POPULATION THEORY A Thesis by GLENN ANTHONY DAVIS Approved as to style and content by: ( rrman Committee) (Head of the Department) (Member) (Member) (Member) (Member) (Member...
NSDL National Science Digital Library
Ms. Popwell
2010-09-22
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! ...
Guinski, Rodrigo 1980-
2012-11-30
This work consists of a set of eight vector graphics animations exploring phasing loops, intended to be displayed on televisions and monitors, for home use or exhibition in art galleries as Generative Cinema installations. ...
Kabal, Peter
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
Optimum bending factor of intraocular lenses in pseudophakic eyes with high myopia
E. R. Villegas; L. Carretero; A. Fimia
1997-01-01
In this paper the range of optimum lens shapes for theoretical pseudophakic eyes with high myopia is given as a function of intraocular lens (IOL) power using physiological and optical design criteria.Wave-front aberration in the plane of the exit pupil in pseudophakic eyes with high myopia is studied. Taking into account the defocus and spherical aberration coefficients, we have used
Optimum Electron Distributions for Space Charge Dominated Beams in Photoinjectors
Limborg-Deprey, C.; Bolton, P.R.; /SLAC
2006-06-15
The optimum photo-electron distribution from the cathode of an RF photoinjector producing a space charge dominated beam is a uniform distribution contained in an ellipsoid. For such a bunch distribution, the space charge forces are linear and the emittance growth induced by those forces is totally reversible and consequently can be compensated. With the appropriate tuning of the emittance compensation optics, the emittance, at the end of photoinjector beamline, for an ellipsoidal laser pulse, would only have two contributions, the cathode emittance and the RF emittance. For the peak currents of 50A and 100 A required from the SBand and L-Band RF gun photoinjectors discussed here, the RF emittance contribution is negligible. If such an ellipsoidal photo-electron distribution were available, the emittance at the end of the beamline could be reduced to the cathode emittance. Its value would be reduced by more than 40% from that obtained using cylindrical shape laser pulses. This potentially dramatic improvement warrants review of the challenges associated with the production of ellipsoidal photo-electrons. We assume the photo-electrons emission time to be short enough that the ellipsoidal electron pulse shape will come directly from the laser pulse. We shift the challenge to ellipsoidal laser pulse shaping. To expose limiting technical issues, we consider the generation of ellipsoidal laser pulse shape in terms of three different concepts.
Optimum Coherent Phase and Frequency Demodulation of a Class of Modulating Spectra
A. J. Viterbi; C. R. Cahn
1964-01-01
The optimum phase-locked loop demodulator is obtained for a carrier, phase modulated by a stationary Gaussian modulating process whose spectrum is proportional to 1\\/1 + (f\\/B)2n where n is any positive integer. Results are obtained also when the carrier is frequency modulated by the process for the limiting cases n = 1 and as n approaches infinity. It is shown
Bryce Canyon's Navajo Loop Trail
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...
Optimum reentry trajectories of a lifting vehicle
NASA Technical Reports Server (NTRS)
Chern, J. S.; Vinh, N. X.
1978-01-01
The optimum maneuver of a space shuttle vehicle reentering a spherical, stationary, and locally exponential atmosphere was investigated. The use of Chapman's modified variables and a rescaled lift-drag polar leads to the formulation of a set of dimensionless equations of motion for flight analysis. The resulting equations are exact in the sense that they are also valid for flight in the vacuum. For planar flight several typical optimum maneuvers are investigated at different altitude ranges, low, moderate and very high. For three-dimensional flight, the procedure to solve the optimum trajectory for maximum cross range is discussed. Finally, using the equilibrium glide condition the maximum cross ranges for entry from circular speed, for several values of E*, and the footprint for E* = 1.5 are computed in this reduced problem.
Optimum spectral bands for land cover discrimination
NASA Astrophysics Data System (ADS)
Tamilarasan, V.; Sharma, S. K.; Nagabhushana, S. R.
An experiment was undertaken to select the optimum spectral bands for the discrimination of land use/cover for proposed Indian Remote Sensing Satellite. A feature selection method was used for the discrimination analysis on the multiband data collected by Bendix 11-channel Modular Multiband Scanner over Tirupati test site of Chittoor district, Andhra Pradesh, South India. Of the various combinations of bands analysed, the optimum combination of four bands was defined as that one which provided the greatest divergence distances to discriminate the specific land covers in the test sites. On the basis of the above studies the optimum bands so chosen are 0.49-0.54 ?m, 0.62-0.66 ?m, 0.66-0.70 ?m and 0.77-0.86 ?m.
Optimum Suction Distribution for Transition Control
NASA Technical Reports Server (NTRS)
Balakumar, P.; Hall, P.
1996-01-01
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.
Optimum Detection of Frequency-Hopped Signals
NASA Technical Reports Server (NTRS)
Cheng, Unjeng; Levitt, Barry; Polydoros, Andreas; Simon, Marvin K.
1992-01-01
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.
Optimum working curve for diesel engines
Souza, E.G. de; Catarina, A.S.
1999-06-01
The optimum working curve (OWC) provides the optimum torque-speed relation required for the design of a tractor gear selection indicator. Three methods for the determination of the OWC curve for diesel engines were tested. One method, called the model-plus-test, uses a quadratic equation and it was obtained analytically. The last two are linear approximations and they provide good accuracy. They have two advantages over the analytical method: the expressions are simple and they do not require additional engine tests.
Warne, Larry Kevin; Lucero, Larry Martin; Langston, William L.; Salazar, Robert Austin; Coleman, Phillip Dale; Basilio, Lorena I.; Bacon, Larry Donald
2012-05-01
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.
Design of optimum supercontinuum spectrum generation in a dispersion decreasing fiber
NASA Astrophysics Data System (ADS)
Xu, Yong-zhao; Ye, Hai; Li, Hong-tao; Ling, Dong-xiong
2015-05-01
In this paper, the optimum supercontinuum (SC) spectrum generation in a dispersion decreasing fiber is presented. Three normalized parameters for the pump pulse and SC fiber are introduced. It is found that the shape of an SC spectrum is uniquely specified by the input soliton order, the normalized dispersion slope and the normalized effective fiber length. For a pumping condition with a given input soliton order and a given normalized dispersion slope, by optimizing the normalized effective fiber length, the residual spectral peak in the SC spectrum can be suppressed effectively, and a broad SC spectrum with optimum spectral flatness can be obtained.
Common Core: Teaching Optimum Topic Exploration (TOTE)
ERIC Educational Resources Information Center
Karge, Belinda Dunnick; Moore, Roxane Kushner
2015-01-01
The Common Core has become a household term and yet many educators do not understand what it means. This article explains the historical perspectives of the Common Core and gives guidance to teachers in application of Teaching Optimum Topic Exploration (TOTE) necessary for full implementation of the Common Core State Standards. An effective…
DEVELOPMENT OF OPTIMUM DESIGN CONFIGURATION AND
on the following six RD&D program areas: · Residential and Commercial Building End-Use Energy Efficiency · Industrial/Agricultural/Water End-Use Energy Efficiency · Renewable Energy Technologies · EnvironmentallyDEVELOPMENT OF OPTIMUM DESIGN CONFIGURATION AND PERFORMANCE FOR VERTICAL AXIS WIND TURBINE Prepared
On the optimum sizing of cooling towers
M. S Söylemez
2001-01-01
The optimum heat and mass transfer area at which minimum cost exists throughout the technical life of forced draft counter-current cooling towers is studied in the present work. Original formulae are developed and presented for the best thermoeconomical performance as a design point.
Optimum systems for satellite fire detection
Tiziana Beltramonte; Maurizio di Bisceglie; Carmela Galdi
2010-01-01
Significant improvements on the detection of thermal anomalies in multispectral satellite data can be obtained when both the false alarm rate and the probability of detection are known. A desirable, optimum system should have constant false alarm rate and maximum probability of detection. While proper hypotheses can be done on the background statistical distribution, on target for constant false alarm
The Patient's Responsibility for Optimum Healthcare
Douglas P. Olsen
2000-01-01
Although clinicians have an obligation to act in patients' best interests, patients frequently choose to act in ways that adversely affect health. Consequently, clinicians are often left questioning where the responsibility for optimum care lies. The criteria for determining responsibility (the Jonas criteria) are as follows: causality, control and foresight. Two types of choices lead to health problems - lifestyle
Optimum Design of Coal Gasification Plants
Pohani, B. P.; Ray, H. P.; Wen, H.
1982-01-01
by using a combination of radiant/convective waste heat boiler or by direct water quench before processing of the raw gas. The selection of an optimum heat recovery system is a function of the product slate, overall economics, and the technical risks...
Transponder Power Minimization Utilizing Optimum Channelizer Gains
John J. Knab
2012-01-01
Today, the Wideband Global SATCOM (WGS) system employs a new concept of adjusting the transponder power gain of individual links. A simple optimum method is derived for selecting these individual channel gains to minimize the amount of transponder power utilized. This new method directly solves a set of simple nonlinear equations and does not utilize any search algorithms or matrix
Finite-time optimum refrigeration cycles
Mohand A. Ait-Alia
1995-01-01
A class of conceptual optimum refrigeration cycles is considered with a fixed overall heat conductance and a specified refrigerant operating temperature range to bound the optimization problems. These cycles deal with maximum refrigeration power, maximum refrigeration load, and maximum heat rejection load for the case of a heat pump. The resulting one degree of freedom problems are solved with a
Optimum Probability Estimation from Empirical Distributions.
ERIC Educational Resources Information Center
Fuhr, Norbert; Huther, Hubert
1989-01-01
Discusses the interdependencies between parameter estimation and properties of probabilistic models, such as dependency assumptions, binary vs. nonbinary features, and estimation sample selection. An optimum estimation for binary features applicable to information retrieval is defined, a method for computing this estimation using empirical data is…
Optimum probability estimation from empirical distributions
Norbert Fuhr; Hubert Hüther
1989-01-01
Probability estimation is important for the application of probabilistic models as well as for any evaluation in IR. We discuss the interdependencies between parameter estimation and certain properties of probabilistic models: dependence assumptions, binary vs. non- binary features, estimation sample selection. Then we define an optimum estimate for binary features which can be applied to various typical estimation problems in
Concerning Optimum Frequencies for Space Vehicle Communication
S. Perlman; L. Kelley; W. Russell; W. Stuart
1959-01-01
Optimum frequencies for the varied needs of space vehicle communication can best be determined from the estimated system performance. Each of the contributing equipment and propagation factors over the range of the radio frequency spectrum affects the minimum tolerable signal-to-noise power ratio at the receiver. Over the range of the radio frequency spectrum, the behavior of the individual building blocks,
Optimum Watermark Detection in Color Images
Elisa Sayrol; Josep Vidal; Silvia Cabanillas; Sonia Santamaria
1999-01-01
This work concentrates on the problem of watermarking embedding and optimum detection in color images through the use of spread spectrum techniques, both in spa ce (Direct Sequence Spread Spectrum or DSSS) and frequency (Frequency Hopping). It is applied to RGB and opponent color component representations. Perceptive information is considered in both color systems. Some tests are performed in order
Transverse kink oscillations of expanding coronal loops
Ballai, Istvan
2012-01-01
We investigate the nature of transverse kink oscillations of loops expanding through the solar corona and how can oscillations be used to diagnose the plasma parameters and the magnetic field. In particular, we aim to analyse how the temporal dependence of the loop length (here modelling the expansion) will affect the P1 /P2 period ratio of transverse loop oscillations. Due to the uncertainty of the loop's shape through its expansion, we discuss separately the case of the loop that maintains its initial semi-circular shape and the case of the loop that from a semi-circular shape evolve into an elliptical shape loop. The equations that describe the oscillations in expanding flux tube are complicated due to the spatial and temporal dependence of coefficients. Using the WKB approximation we find approximative values for periods and their evolution, as well as the period ratio. For small values of time (near the start of the expansion) we can employ a regular perturbation method to find approximative relations fo...
Optimum annular focusing by a phase plate
Arrizón, Victor; Aguirre-Olivas, Dilia; Mellado-Villaseñor, Gabriel
2015-01-01
Conventional light focusing, i. e. concentration of an extended optical field within a small area around a point, is a frequently used process in Optics. An important extension to conventional focusing is the generation of the annular focal field of an optical beam. We discuss a simple optical setup that achieves this kind of focusing employing a phase plate as unique optical component. We first establish the class of beams that being transmitted through the phase plate can be focused into an annular field with topological charge of arbitrary integer order q. Then, for each beam in this class we determine the plate transmittance that generates the focal field with the maximum possible peak intensity. In particular, we discuss and implement experimentally the optimum annular focusing of a Gaussian beam. The attributes of optimum annular focal fields, namely the high peak intensity, intensity gradient and narrow annular section, are advantageous for different applications of such structured fields.
Optimum routing of a sailing wind farm
Masaru Tsujimoto; Takashi Uehiro; Hiroshi Esaki; Takeshi Kinoshita; Ken Takagi; Susumu Tanaka; Hiroshi Yamaguchi; Hideo Okamura; Masuho Satou; Yoshimasa Minami
2009-01-01
To acquire the wind energy of the oceans, a sailing wind farm has been proposed. The wind farm considered is composed of a\\u000a semisubmersible floating structure, 11 windmills, four sails, six thrusters, and storage for hydrogen. To maximize the acquired\\u000a energy, an effective algorithm to search for optimum routes was developed. The algorithm is based on the fact that beam
Optimum resource use in synfuels development
C. D. Livengood; K. E. Wilzbach
1981-01-01
In this paper the question of optimum coal-resource use is examined. One conclusion is that electricity, substituted for oil or gas, is in some areas the most resource-efficient synfuel. The move toward the all-electric home, which has been the historical trend, should be encouraged. The development and commercialization of advanced, high-efficiency power plants will enhance the advantages of such increased
Optimum plane diffusers in laminar flow
Hayri Cabuk; Vijay Modi
1992-01-01
The paper considers an optimum design of an internal flow component such as a diffuser in laminar flow. The problem of determining the profile of a plane diffuser of given upstream width and length that provides the maximum static pressure rise is solved for 2D incompressible laminar flow governed by the steady-state Navier-Stokes equations. A set of 'adjoint' equations is
NSDL National Science Digital Library
Meghan Hauptli
2012-06-11
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.
Maximizing Combustion Efficiency Through Selection of Optimum CO Control Levels
McGowan, G. F.; Ketchum, R. L.
1985-01-01
guidelines for maintaining maximum boiler efficiency. This paper will present an analytical technique for establishing an optimum value of CO to minimize thermal losses in the combustion process. The optimum value is established by finding that value...
NASA Technical Reports Server (NTRS)
Ott, Eric A.
2005-01-01
Scoping of shape changing airfoil concepts including both aerodynamic analysis and materials-related technology assessment effort was performed. Three general categories of potential components were considered-fan blades, booster and compressor blades, and stator airfoils. Based on perceived contributions to improving engine efficiency, the fan blade was chosen as the primary application for a more detailed assessment. A high-level aerodynamic assessment using a GE90-90B Block 4 engine cycle and fan blade geometry indicates that blade camber changes of approximately +/-4deg would be sufficient to result in fan efficiency improvements nearing 1 percent. Constraints related to flight safety and failed mode operation suggest that use of the baseline blade shape with actuation to the optimum cruise condition during a portion of the cycle would be likely required. Application of these conditions to the QAT fan blade and engine cycle was estimated to result in an overall fan efficiency gain of 0.4 percent.
PID controller auto-tuning based on process step response and damping optimum criterion.
Pavkovi?, Danijel; Polak, Siniša; Zorc, Davor
2014-01-01
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
Optimum structural design with static aeroelastic constraints
NASA Technical Reports Server (NTRS)
Bowman, Keith B; Grandhi, Ramana V.; Eastep, F. E.
1989-01-01
The static aeroelastic performance characteristics, divergence velocity, control effectiveness and lift effectiveness are considered in obtaining an optimum weight structure. A typical swept wing structure is used with upper and lower skins, spar and rib thicknesses, and spar cap and vertical post cross-sectional areas as the design parameters. Incompressible aerodynamic strip theory is used to derive the constraint formulations, and aerodynamic load matrices. A Sequential Unconstrained Minimization Technique (SUMT) algorithm is used to optimize the wing structure to meet the desired performance constraints.
NSDL National Science Digital Library
Mr. Shane Carter
2006-10-23
Get a better understanding of the importance of our basic geometric shapes. While going through the activity below see if you can create the following shapes: A triangle, square, parallelogram, trapezoid, rectangle, kite, diamond. Having fun with quadrilaterals Now that you can create basic shapes see if you can create more difficult shapes on the geoboard. Geoboard Activity See if you can use the geoboard to create 3-D shapes ...
Caravelli, Francesco
2010-01-01
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...
Preisach modeling of piezoceramic and shape memory alloy hysteresis
Declan Hughes; John T. Wen
1995-01-01
Smart materials such as piezoceramics and shape memory alloys (SMAs) exhibit significant hysteresis and in order to estimate the effect on open and closed loop control a suitable model is needed. One promising candidate is the Preisach independent domain hysteresis model that is characterized by the congruent minor loop and wiping out properties. Comparable minor loop and decaying oscillation test
Leaping of a flexible loop on water
NASA Astrophysics Data System (ADS)
Kim, Ho-Young; Yang, Eun Jin; Lee, Min-Hee; Shin, Bongsu
2008-11-01
Small aquatic arthropods, such as water striders and fishing spiders, are able to leap on water to a height several times their body length. We study a simple model using a floating flexible loop to provide fundamental understanding and mimicking principle of the leaping on water. Motion of a loop, initially bent into an ellipse from equilibrium circular shape using a thin thread, is visualized with a high speed camera upon cutting the thread with a laser. We find that the loop may merely oscillate while afloat, penetrate into the water, or soar into air depending on the hydrophobicity, the bending stiffness, the weight and the degree of initial deflection of the loop. We also construct a scaling law for the leaping height by balancing the initial elastic bending energy with the loop's translational and vibrational energy and a loss imparted to the water in the forms of interfacial, kinetic and viscous energy.
NASA Astrophysics Data System (ADS)
Caruthers, J. W.
1982-10-01
This study provides an overview of Soviet work in the subject of optimum signal discrimination techniques. Its purpose is to aid U.S. scientists in becoming more familiar with an extensive signal processing effort of which they undoubtedly have had little prior awareness. It provides general substantive comment and bibliographic resource materials. If this work is successful in accomplishing its goal, it will serve as an example of reverse technology transfer. The Soviets have, for several decades, taken a more rigorous statistical approach to the study of oceanic processes and the theory of detection signals in the ocean environment than has the United States. The Soviets view this environmental as non-Gaussian, nonstationary, and nonwhite, and do not avoid the complications this presents to the formulation of the theory of optimum signal detection and estimation. There appears to be poor U.S. access to this work. The United States would probably benefit from selected uses of Soviet theory and algorithm developments in this topic. Soviet development of optimum signal detection and estimation techniques is broadly based, covering various aspects of radar, sonar, and communications. They have an extensive program in the development of optimum space-time processing (OSTP) and have extended the theory further than has the U.S. Their effort is based on the Karhunen-Loeve expansion extended to nonstationary space-time signals and noise.
Chiral properties of topological-state loops
NASA Astrophysics Data System (ADS)
Gruji?, Marko M.; Tadi?, Milan Ž.; Peeters, François M.
2015-06-01
The angular momentum quantization of chiral gapless modes confined to a circularly shaped interface between two different topological phases is investigated. By examining several different setups, we show analytically that the angular momentum of the topological modes exhibits a highly chiral behavior, and can be coupled to spin and/or valley degrees of freedom, reflecting the nature of the interface states. A simple general one-dimensional model, valid for arbitrarily shaped loops, is shown to predict the corresponding energies and the magnetic moments. These loops can be viewed as building blocks for artificial magnets with tunable and highly diverse properties.
The optimum dimensions of radiative spines
NASA Astrophysics Data System (ADS)
Razani, A.; Zohoor, H.
Radiative pin fins (spines) are important in conjunction with heat rejection systems for space applications. In the design of radiators for space applications, spines possessing minimum mass are of great interest. In this study a conducting-radiating spine with an arbitrary profile is considered. The profile is assumed to be a function of the temperature in the spines by introducing a free parameter. With this choice of profile, the nonlinear heat transfer equation for the conducting-radiating spine can be integrated analytically. Using this method, a nonlinear integral equation for the temperature of the spine is obtained. This equation can be conveniently solved numerically to find the optimum dimensions of the spine.
Optimum runway orientation relative to crosswinds
NASA Technical Reports Server (NTRS)
Falls, L. W.; Brown, S. C.
1972-01-01
Specific magnitudes of crosswinds may exist that could be constraints to the success of an aircraft mission such as the landing of the proposed space shuttle. A method is required to determine the orientation or azimuth of the proposed runway which will minimize the probability of certain critical crosswinds. Two procedures for obtaining the optimum runway orientation relative to minimizing a specified crosswind speed are described and illustrated with examples. The empirical procedure requires only hand calculations on an ordinary wind rose. The theoretical method utilizes wind statistics computed after the bivariate normal elliptical distribution is applied to a data sample of component winds. This method requires only the assumption that the wind components are bivariate normally distributed. This assumption seems to be reasonable. Studies are currently in progress for testing wind components for bivariate normality for various stations. The close agreement between the theoretical and empirical results for the example chosen substantiates the bivariate normal assumption.
On the optimality of the MAP estimation loop for carrier phase tracking BPSK and QPSK signals
NASA Technical Reports Server (NTRS)
Simon, M. K.
1979-01-01
Starting with MAP estimation theory as a basis for optimally estimating carrier phase of BPSK and QPSK modulations, it is shown in this paper that the closed loop phase trackers, which are motivated by this approach, are indeed closed loop optimum in the minimum mean-square phase tracking jitter sense. The corresponding squaring loss performance of these so-called MAP estimation loops is compared with that of more practical implementations wherein the hyperbolic tangent nonlinearity is approximated by simpler functions.
Optimum multistage genomic selection in dairy cattle.
Börner, V; Teuscher, F; Reinsch, N
2012-04-01
The availability of different single nucleotide polymorphism (SNP) chips and the development of imputation algorithms allow for multistage dairy cattle breeding schemes applying various genomic selection strategies. These SNP genotypes yield genomically estimated breeding values (GEBV) with different accuracies at different costs. Thus, the optimum allocation of investments to different selection paths and strategies to maximize the genetic gain per year (?G(a)) and its sensitivity to changes in cost and accuracies of GEBV is of great interest. This is even more relevant under the constraints of limited financial resources. With deterministic methods, optimum multistage breeding plans maximizing ?G(a) were identified in which selection could take place on GEBV derived from high-density (GEBV(HD)) and low-density (GEBV(LD)) SNP genotypes. To account for the uncertainty of cost and accuracies of GEBV, these parameters were varied in a semi-continuous manner. Overall breeding costs were limited to the crucial expenses of a traditional breeding program with 50 progeny-tested young bulls per year. Results clearly show that, in an optimal selection strategy, selection on GEBV(LD) is predominantly used for the identification of future bull dams but the main part of ?G(a) is still generated from selection of sires. The low selection intensity in the path dam to sire induced a higher sensitivity of ?G(a) to changes in cost and accuracies of GEBV(LD) compared with the same changes of GEBV(HD). On the contrary, the genetic gain generated from selection of males was only affected by changes in accuracies of GEBV(HD) but almost unaffected by any changes in cost. Thus, changes in cost and accuracies of GEBV(LD) put the most pressure on the breeding scheme structure to maintain a high ?G(a). Furthermore, genomic selection of bull dams produced by far the majority of breeding cost but the lowest genetic gain. PMID:22459855
NSDL National Science Digital Library
The Shodor Education Foundation, Inc.
2007-12-12
This interactive applet operates in one of two modes: auto draw and create shape mode, allowing the user to explore the area and perimeter of non-standard shapes. Immediate feedback is given on answers entered.
NSDL National Science Digital Library
2013-01-21
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.
2010-01-01
Background Systems biology research and applications require creation, validation, extensive usage of mathematical models and visualization of simulation results by end-users. Our goal is to develop novel method for visualization of simulation results and implement it in simulation software package equipped with the sophisticated mathematical and computational techniques for model development, verification and parameter fitting. Results We present mathematical simulation workbench DBSolve Optimum which is significantly improved and extended successor of well known simulation software DBSolve5. Concept of "dynamic visualization" of simulation results has been developed and implemented in DBSolve Optimum. In framework of the concept graphical objects representing metabolite concentrations and reactions change their volume and shape in accordance to simulation results. This technique is applied to visualize both kinetic response of the model and dependence of its steady state on parameter. The use of the dynamic visualization is illustrated with kinetic model of the Krebs cycle. Conclusion DBSolve Optimum is a user friendly simulation software package that enables to simplify the construction, verification, analysis and visualization of kinetic models. Dynamic visualization tool implemented in the software allows user to animate simulation results and, thereby, present them in more comprehensible mode. DBSolve Optimum and built-in dynamic visualization module is free for both academic and commercial use. It can be downloaded directly from http://www.insysbio.ru. PMID:20698988
New floating floor design with optimum isolator location
NASA Astrophysics Data System (ADS)
Hui, C. K.; Ng, C. F.
2007-06-01
In this paper, a new design concept of an isolated honeycomb floor with a special arrangement of isolators is proposed to improve the vibration isolation performance of conventional lightweight cement floor panels in the frequency range of 120-600 Hz. The symmetric bending resonance frequencies and mode shapes of a honeycomb floor panel were identified by a shaker test. The effects on vibration isolation of isolator position and acoustic insulation were then investigated using experimental modal analysis. The analysis suggests that four design features ensure the optimum vibration isolation performance of a square floating honeycomb floor: the floor panel should be small, stiff, and lightweight; the isolators must be placed at the nodal points of the symmetric bending modes of the floor panel; the vibration must be transmitted via the center point of the floor panel; and acoustic insulation material should be installed inside the cavity. The proposed floating floor design achieved a vibration reduction of 20-30 dB in the frequency range of 120-600 Hz. In addition, the proposed floor was found to have a 20 dB lower vibration level at the first bending resonance frequency than the conventional design with isolators that are placed at the edges.
Light driven motor using shape memory alloy
Hideki Okamura
2010-01-01
A light-driven motor driven by a single source of light is demonstrated for the first time. The system utilizes a NiTi shape memory alloy (SMA) wire initially trained straight shape. The SMA wire was formed in a loop and put around two wheels. The wire undergoes change in the radius of curvature as it rotates, and when light is irradiated
An integrated optimum design approach for high speed prop rotors
NASA Technical Reports Server (NTRS)
Chattopadhyay, Aditi; Mccarthy, Thomas R.
1995-01-01
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.
NATURAL CONVECTION INPILE LOOP
Sparrell
1957-01-01
A small, natural-convection, NaK-cooled in-pile loop is described. The ; loop has a 3-in. diameter and is 7-ft long. The loop is designed for testing ; small fuel pins at highpower densities. Temperature control in the loop is ; achieved by controlling the coolant flow rate. (T.F.H.);
Mingsheng Ying; Yuan Feng
2007-01-04
Loop is a powerful program construct in classical computation, but its power is still not exploited fully in quantum computation. The exploitation of such power definitely requires a deep understanding of the mechanism of quantum loop programs. In this paper, we introduce a general scheme of quantum loops and describe its computational process. The notions of termination and almost termination are proposed for quantum loops, and the function computed by a quantum loop is defined. To show their expressive power, quantum loops are applied in describing quantum walks. Necessary and sufficient conditions for termination and almost termination of a general quantum loop on any mixed input state are presented. A quantum loop is said to be (almost) terminating if it (almost) terminates on any input state. We show that a quantum loop is almost terminating if and only if it is uniformly almost terminating. It is observed that a small disturbance either on the unitary transformation in the loop body or on the measurement in the loop guard can make any quantum loop (almost) terminating. Moreover, a representation of the function computed by a quantum loop is given in terms of finite summations of matrices. To illustrate the notions and results obtained in this paper, two simplest classes of quantum loop programs, one qubit quantum loops, and two qubit quantum loops defined by controlled gates, are carefully examined.
Global optimum protein threading with gapped alignment and empirical pair score functions.
Lathrop, R H; Smith, T F
1996-02-01
We describe a branch-and-bound search algorithm for finding the exact global optimum gapped sequence-structure alignment ("threading") between a protein sequence and a protein core or structural model, using an arbitrary amino acid pair score function (e.g. contact potentials, knowledge-based potentials, potentials of mean force, etc.). The search method imposes minimal conditions on how structural environments are defined or the form of the score function, and allows arbitrary sequence-specific functions for scoring loops and active site residues. Consequently the search method can be used with many different score functions and threading methodologies; this paper illustrates five from the literature. On a desktop workstation running LISP, we have found the global optimum protein sequence-structure alignment in NP-hard search spaces as large as 9.6 x 10(31), at rates ranging as high as 6.8 x 10(28) equivalent threadings per second (most of which are pruned before they ever are examined explicitly). Continuing the procedure past the global optimum enumerates successive candidate threadings in monotonically increasing score order. We give efficient algorithms for search space size, uniform random sampling, segment placement probabilities, mean, standard deviation and partition function. The method should prove useful for structure prediction, as well as for critical evaluation of new pair score functions. PMID:8568903
The preprocessed doacross loop
NASA Technical Reports Server (NTRS)
Saltz, Joel H.; Mirchandaney, Ravi
1990-01-01
Dependencies between loop iterations cannot always be characterized during program compilation. Doacross loops typically make use of a-priori knowledge of inter-iteration dependencies to carry out required synchronizations. A type of doacross loop is proposed that allows the scheduling of iterations of a loop among processors without advance knowledge of inter-iteration dependencies. The method proposed for loop iterations requires that parallelizable preprocessing and postprocessing steps be carried out during program execution.
MBG holograms under the optimum conditions
NASA Astrophysics Data System (ADS)
Zhao, Jian-ming; Li, Min-qian; Pan, Jin-fang; Wang, Junmin; Sun, Meng-jia
1996-12-01
A systematic investigation is carried out on the optimization of diffraction efficiency (DE) of only methylene blue sensitized gelatin (MBG) holograms. The influence of the following factors on DE are studied: the concentration of methylene blue (Cm), the concentration of ammonium dichromate solution (Ca), swelling temperature (Ts), exposure (E) and the relative humidity of air (RH). This study shows that under the condition of Cm-0.009%; Ca- 5%; Ts within 35 - 45 degree(s)C; E-150 mJ/cm2; RH within 45 - 65%, an optimum DE of over 80%, even 90% can be achieved in MBG holograms. In our experiments we find that a moderate DE(35%) is obtained without dichromate solution in post- processing. In order to know the role which the condition of bathing the plate in a dichromate solution plays and the photo-chemical mechanism of forming the interference pattern in the films, the X-ray spectra are made, the Cr3+ ligands are not found; this means that the quantity of Cr3+ ligands is too small to measure, even if its is existing in the processed film. These results can not be interpreted with the normal photo-chemical mechanism of forming the holograms.
Optimum coding techniques for MST radars
NASA Technical Reports Server (NTRS)
Sulzer, M. P.; Woodman, R. F.
1986-01-01
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.
Optimum deposition conditions of ultrasmooth silver nanolayers
2014-01-01
Reduction of surface plasmon-polariton losses due to their scattering on metal surface roughness still remains a challenge in the fabrication of plasmonic devices for nanooptics. To achieve smooth silver films, we study the dependence of surface roughness on the evaporation temperature in a physical vapor deposition process. At the deposition temperature range 90 to 500 K, the mismatch of thermal expansion coefficients of Ag, Ge wetting layer, and sapphire substrate does not deteriorate the metal surface. To avoid ice crystal formation on substrates, the working temperature of the whole physical vapor deposition process should exceed that of the sublimation at the evaporation pressure range. At optimum room temperature, the root-mean-square (RMS) surface roughness was successfully reduced to 0.2 nm for a 10-nm Ag layer on sapphire substrate with a 1-nm germanium wetting interlayer. Silver layers of 10- and 30-nm thickness were examined using an atomic force microscope (AFM), X-ray reflectometry (XRR), and two-dimensional X-ray diffraction (XRD2). PACS 63.22.Np Layered systems; 68. Surfaces and interfaces; thin films and nanosystems (structure and nonelectronic properties); 81.07.-b Nanoscale materials and structures: fabrication and characterization PMID:24685115
Optimum deposition conditions of ultrasmooth silver nanolayers
NASA Astrophysics Data System (ADS)
Stefaniuk, Tomasz; Wróbel, Piotr; Górecka, Ewa; Szoplik, Tomasz
2014-03-01
Reduction of surface plasmon-polariton losses due to their scattering on metal surface roughness still remains a challenge in the fabrication of plasmonic devices for nanooptics. To achieve smooth silver films, we study the dependence of surface roughness on the evaporation temperature in a physical vapor deposition process. At the deposition temperature range 90 to 500 K, the mismatch of thermal expansion coefficients of Ag, Ge wetting layer, and sapphire substrate does not deteriorate the metal surface. To avoid ice crystal formation on substrates, the working temperature of the whole physical vapor deposition process should exceed that of the sublimation at the evaporation pressure range. At optimum room temperature, the root-mean-square (RMS) surface roughness was successfully reduced to 0.2 nm for a 10-nm Ag layer on sapphire substrate with a 1-nm germanium wetting interlayer. Silver layers of 10- and 30-nm thickness were examined using an atomic force microscope (AFM), X-ray reflectometry (XRR), and two-dimensional X-ray diffraction (XRD2).
Optimum flight paths of turbojet aircraft
NASA Technical Reports Server (NTRS)
Miele, Angelo
1955-01-01
The climb of turbojet aircraft is analyzed and discussed including the accelerations. Three particular flight performances are examined: minimum time of climb, climb with minimum fuel consumption, and steepest climb. The theoretical results obtained from a previous study are put in a form that is suitable for application on the following simplifying assumptions: the Mach number is considered an independent variable instead of the velocity; the variations of the airplane mass due to fuel consumption are disregarded; the airplane polar is assumed to be parabolic; the path curvatures and the squares of the path angles are disregarded in the projection of the equation of motion on the normal to the path; lastly, an ideal turbojet with performance independent of the velocity is involved. The optimum Mach number for each flight condition is obtained from the solution of a sixth order equation in which the coefficients are functions of two fundamental parameters: the ratio of minimum drag in level flight to the thrust and the Mach number which represents the flight at constant altitude and maximum lift-drag ratio.
Sandstone Formation on the Navajo Loop Trail
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...
Hoodoo on the Navajo Loop Trail
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...
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...
Chaotic Flow Regimes in a Convection Loop
M. Gorman; P. J. Widmann; K. A. Robbins
1984-01-01
In our experiments on a loop of fluid heated with a constant flux on the bottom half and cooled at a constant temperature on the top half, we have observed three chaotic flow regimes: a globally chaotic regime whose essential features can be described by a one-dimensional cusp-shaped map, a subcritical regime in which the flow can be either chaotic
Noise Considerations for Closed Loop Digital Accelerometers
Elena Gaura; Michael Kraft
This paper investigates the noise shaping properties of a sigma-delta modulator type control system applied to a micromachined accelerometer. Three noise sources are present in such an electromechanical closed loop system: mechanical noise due to Brownian motion, electronic noise introduced by the interface circuit due to thermal noise sources in the electronic devices and quantisation noise due to the analog
Shape optimization of impactor penetrating into concrete or limestone targets
G. Ben-Dor; A. Dubinsky; T. Elperin
2003-01-01
The shape of the normally striking impactor that attains the maximum depth of penetration into a concrete or a limestone semi-infinite target for a given impact velocity is found. It is shown that the optimum shape is close to a blunt (in general case) cone and it is independent on the properties of the material of the target in the
An Optimum Design Index of the Bottle with the Vacuum Insulation Structure
NASA Astrophysics Data System (ADS)
Horiuchi, Takuya; Tanaka, Tatsuya; Imaida, Yutaka; Nakai, Keiji; Utsumi, Koji
2011-08-01
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.
Optimum wavelengths for two color ranging
NASA Technical Reports Server (NTRS)
Degnan, John J.
1993-01-01
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.
Optimum design of uncooled staring infrared camera
NASA Astrophysics Data System (ADS)
Li, Yingwen; Pan, Debin; Liu, Aidong; Geng, Anbing; Li, Yong; He, Jun
2006-02-01
Several models of target acquisition range prediction of the uncooled staring camera and their advantages are proposed in the paper. NVTherm is used to evaluate the modulation transfer function, minimum resolvable temperature difference and target acquisition range. The analysis result shows that the performance of the detector is the key factor to limit the performance of the uncooled staring camera. The target acquisition range of the uncooled infrared camera can be improved by increasing effective focus length (EFL) of optical component, decreasing its F/# or reducing the pixel pitch of the detector. The detection range of 1.09 km can be achieved under the condition of 75 mm EFL and F/0.8. When the EFL changes from 75mm to 150 mm under the condition of F/0.8 and 45?m pixel pitch, the detection range of 2.36 km, recognition range of 0.47 km and identification range of 0.24 km have been gotten. When the pixel pitch is reduced to 35?m, the detection range is 2.59 km. Furthermore, when 2 x 2 microscan is adopted in the camera design, then the pixel pitch will change from 35?m to 17.5?m. Although the infrared camera becomes an optical performance limited system, its performance improves a lot to get the detection range of 2.94 km. The field test shows that the detection range to a 1.7 m x 0.45 m target is 2.2 km under the condition of F/0.8, 150mm EFL and 45 ?m pixel pitch, achieving good matches with the evaluation value of 2.36 km through NVTherm. An optimum uncooled infrared design is achieved using the NVTherm software which shortens the design cycle.
Performance of optimum combining with channel estimation errors
Balkan Kecicioglu; Murat Torlak; Adnan Kavak
2005-01-01
óOptimum combining (OC) is an effective way of suppressing interference in receive antenna diversity systems. In this paper, we examine the effect of channel estimation error on bit error probability (BEP) performance of optimum combining with BPSK modulation. The nal expression is dependent on channel estimation error vari- ance. Therefore, our analysis is independent of any specic estimation scheme. First,
Estimating the Optimum Standard Penalty of Examination Timetables
Tayo Sodeinde; George M. White
Examination scheduling is one of the earliest applications of computer tech- nology to an academic problem. The problem is difficult to formulate and it is usually impossible to obtain optimum solutions, or even to estimate how far from optimum a given solution is. This gave a strong impetus to academic researchers to study the problem, given the promise of a
Optimum optical modulation index of laser transmitters in SCM systems
K. Alameh; R. A. Minasian
1990-01-01
An analysis of the optimum optical modulation index of laser transmitters in SCM systems is presented. Nonlinear distortion arising from overmodulation in a laser-limiter combination is studied. A generalized analysis, based on rectangular signal input power spectral density and broadband transmission, is given for the nonlinear noise spectral density. A computer algorithm is developed to generate the optimum modulation index
Construction of an optimum system design method considering product lifecycle
Kenji Doi; Yoshiyuki Chujo; Masataka Yoshimura; Shinji Nishiwaki; Kazuhiro Izui
2009-01-01
This paper proposes an optimum system design method that especially considers product lifecycles and aims to help designers make effective decisions during the product design phase. By considering and estimating all lifecycle factors of cost and environmental impact in addition to the product performance, this method facilitates development of optimum design solutions that incorporate requirements pertaining to the product's entire
Optimum design of B-series marine propellers
M. M. Gaafary; H. S. El-Kilani; M. M. Moustafa
2011-01-01
The choice of an optimum marine propeller is one of the most important problems in naval architecture. This problem can be handled using the propeller series diagrams or regression polynomials. This paper introduces a procedure to find out the optimum characteristics of B-series marine propellers. The propeller design process is performed as a single objective function subjected to constraints imposed
Optimum Power Control for Fading CDMA with Deterministic Sequences
Ulukus, Sennur
@eng.umd.edu Abstract We characterize the optimum power allocation policy that maximizes the information theoretic sum certain mild conditions on the signature sequences, the optimum power allocation dictates that more than in wireless communication networks unless appropriate resource allocation is applied to exploit the variations
Optimum Income Taxation and Layo Taxes Pierre Cahucy
Boyer, Edmond
Optimum Income Taxation and Layo¤ Taxes¤ Pierre Cahucy CREST-INSEE, Université Paris 1, CEPR, IZA This paper analyzes optimum income taxation in a model with endogenous job destruc- tion that gives rise¤ taxes, Optimal taxation, Job destruction. JEL codes: H21, H32, J38, J65 ¤ We wish to thank, without
Optimum College Admissions, Taxes and Tuitions When Completion Is Uncertain.
ERIC Educational Resources Information Center
Garratt, Rod; Marshall, John M.
1995-01-01
Explores the rationale for college subsidies in most world economies, treating precollege achievement as an insurable risk. Contract theory considers optimum insurance contracts for this risk and views public finance of college education as providing the insurance. The theory yields conditions on optimum taxes and fees. Rationing by…
Optimum Replacement Time for Cotton Pickers in Greece
G. Kitsopanidis; E. Mygdakos; T. Gemtos
2005-01-01
In this paper an attempt has been made to determine the optimum replacement time for cotton pickers under the technical and economic conditions in Greece. For this purpose, five relevant methods have been applied to analyze real data taken by 62 cotton pickers working in Central Greece. Three of the methods consider that the optimum replacement time for cotton pickers
THE OPTIMUM HYDROGEN ION CONCENTRATION FOR THE GROWTH OF PNEUMOCOCCUS
K. G. Dernby; O. T. AVERY
1918-01-01
It is well known that pneumococcus grows best in slightly alkaline medium, but the exact degree of alkalinity, in terms of hydrogen ion concentration, necessary for optimum growth does not appear to have been determined. The work of Clark (1915) and Clark andLubs (1917) makes it probable that the limiting and optimum hydrogen ion con- centrations for the growth of
Optimum polynomial retrieval functions based on the probability ranking principle
Norbert Fuhr
1989-01-01
We show that any approach to developing optimum retrieval functions is based on two kinds of assumptions: first, a certain form of representation for documents and requests, and second, additional simplifying assumptions that predefine the type of the retrieval function. Then we describe an approach for the development of optimum polynomial retrieval functions: request-document pairs (fl, dm) are mapped onto
Optimum rotationally symmetric shells for flywheel rotors
Blake, Henry W. (Oak Ridge, TN)
2000-01-01
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.
Optimum rotationally symmetric shells for flywheel rotors
Blake, H.W.
2000-04-04
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.
Serge Belongie; Jitendra Malik; Jan Puzicha
2001-01-01
We present a novel approach to measuring similar- ity between shapes and exploit it for object recogni- tion. In our framework, the measurement of similar- ity is preceded by (1) solving for correspondences be- tween points on the two shapes, (2) using the correspon- dences to estimate an aligning transform. In order to solve the correspondence problem, we attach a
NSDL National Science Digital Library
WGBH
2001-01-01
This online activity features two simulations demonstrating the comparative strengths of rectangles, arches, and triangles when stress is applied at a point. Simulations offer a simplified version of real life conditions related to the strength and stability of structures. For comparison's sake, each tested shape is of equivalent thickness and has hinged joints. The shapes show load distribution arrows when force is applied. In one simulation, a student selects a shape and initiates a dynamic illustration, providing an explanation of the effect of applying force and demonstrating how the shape can be strengthened. The second simulation shows and explains what results when increasing numbers of elephants are stacked on each of the three shapes. Copyright 2005 Eisenhower National Clearinghouse
Two novel automatic frequency tracking loops
NASA Technical Reports Server (NTRS)
Aguirre, Sergio; Hinedi, Sami
1989-01-01
Two automatic-frequency-control (AFC) loops are introduced and analyzed in detail. The algorithms are generalizations of the well known cross-product AFC loop with improved performance. The first estimator uses running overlapping discrete Fourier transforms to create a discriminator curve proportional to the frequency estimation error, whereas the second one preprocesses the received data and then uses an extended Kalman filter to estimate the input frequency. The algorithms are tested by computer simulations in a highly dynamic environment at low carrier/noise ratio (CNR). The algorithms are suboptimum tracking schemes with a larger frequency-error variance compared to an optimum strategy, but they offer simplicity of mechanization and a CNR with a very low operating threshold.
Optimum aerodynamic design via boundary control
NASA Technical Reports Server (NTRS)
Jameson, Antony
1994-01-01
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.
Brigantic, R T; Roggemann, M C; Welsh, B M; Bauer, K W
1998-02-10
We present the results of research aimed at optimizing adaptive-optics closed-loop bandwidth settings to maximize imaging-system performance. The optimum closed-loop bandwidth settings are determined as a function of target-object light levels and atmospheric seeing conditions. Our work shows that, for bright objects, the optimum closed-loop bandwidth is near the Greenwood frequency. However, for dim objects without the use of a laser beacon the preferred closed-loop bandwidth settings are a small fraction of the Greenwood frequency. In addition, under low light levels selection of the proper closed-loop bandwidth is more critical for achieving maximum performance than it is under high light levels. We also present a strategy for selecting the closed-loop bandwidth to provide robust system performance for different target-object light levels. PMID:18268662
Simulations of gyrosynchrotron microwave emission from an oscillating magnetic loop
NASA Astrophysics Data System (ADS)
Kuznetsov, Alexey; Reznikova, Veronika; Van Doorsselaere, Tom; Antolin, Patrick
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.
Optimizing coherent anti-Stokes Raman scattering by genetic algorithm controlled pulse shaping
NASA Astrophysics Data System (ADS)
Yang, Wenlong; Sokolov, Alexei
2010-10-01
The hybrid coherent anti-Stokes Raman scattering (CARS) has been successful applied to fast chemical sensitive detections. As the development of femto-second pulse shaping techniques, it is of great interest to find the optimum pulse shapes for CARS. The optimum pulse shapes should minimize the non-resonant four wave mixing (NRFWM) background and maximize the CARS signal. A genetic algorithm (GA) is developed to make a heuristic searching for optimized pulse shapes, which give the best signal the background ratio. The GA is shown to be able to rediscover the hybrid CARS scheme and find optimized pulse shapes for customized applications by itself.
Optimum Unambiguous Discrimination of Linearly Independent Pure States
Shengshi Pang; Shengjun Wu
2009-11-30
Given $n$ linearly independent pure states and their prior probabilities, we study the problem of optimum unambiguous discrimination of these states. We derive the properties of the optimum solution and the equations that must be satisfied by the optimum measurement strategy which achieves the maximum average success probability, and also give the detailed steps to obtain the optimum solution and the optimum measurement strategy. The general method and results we obtain are also illustrated both numerically and geometrically. We derive a simple analytical formula of the maximum average success probability of unambiguous discrimination for a given set of pure states, and it can be used to simplify the calculation of the optimum solution in some situations. We also obtain the analytical solution of a generalized equal-probability measurement problem using the equations we introduce. Finally, as another application of our result, we study the optimum unambiguous discrimination problem of three linearly independent pure states in details and obtain analytical solutions for some special cases.
NSDL National Science Digital Library
Illuminations National Council of Teachers of Mathematics
2009-10-26
"Students will balance shapes on the pan balance applet to study equality, essential to understanding algebra. Equivalent relationships will be recognized when the pans balance, demonstrating the properties of equality." (from NCTM's Illuminations)
NSDL National Science Digital Library
2012-01-01
This interactive tool allows a user to create many geometric shapes. Squares, triangles, rhombi, trapezoids and hexagons can be created, colored, enlarged, shrunk, rotated, reflected, sliced, and glued together.
Investigation of earthquake factor for optimum tuned mass dampers
NASA Astrophysics Data System (ADS)
Nigdeli, Sinan Melih; Bekda?, Gebrail
2012-09-01
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.
NSDL National Science Digital Library
This activity gives students an opportunity to explore some of the common 3-D shapes and their names and properties. After discussion and an example, it asks students to count the required number of edges and vertices (corners) to build each of 5 given shapes. The Teachers' Notes page includes suggestions for implementation, discussion questions, ideas for extension and support, and a printable recording sheet (pdf).
NSDL National Science Digital Library
2012-06-26
In this activity (25th on the page) about learning and memory, learners explore a training method that animal trainers employ called "shaping." Working in pairs, learners will attempt to "shape" each other to complete a task through rewarding and reinforcing positive behavior. Learners will earn "treats" for each correct behavior. Use this activity to teach learners how behaviors can be learned and trained and/or how trainers use non-verbal techniques to work with animals.
NSDL National Science Digital Library
Exploratorium
2010-01-01
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.
Equilibrium models of coronal loops that involve curvature and buoyancy
Hindman, Bradley W. [JILA and Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309-0440 (United States); Jain, Rekha, E-mail: hindman@solarz.colorado.edu [School of Mathematics and Statistics, University of Sheffield, Sheffield S3 7RH (United Kingdom)
2013-12-01
We construct magnetostatic models of coronal loops in which the thermodynamics of the loop is fully consistent with the shape and geometry of the loop. This is achieved by treating the loop as a thin, compact, magnetic fibril that is a small departure from a force-free state. The density along the loop is related to the loop's curvature by requiring that the Lorentz force arising from this deviation is balanced by buoyancy. This equilibrium, coupled with hydrostatic balance and the ideal gas law, then connects the temperature of the loop with the curvature of the loop without resorting to a detailed treatment of heating and cooling. We present two example solutions: one with a spatially invariant magnetic Bond number (the dimensionless ratio of buoyancy to Lorentz forces) and the other with a constant radius of the curvature of the loop's axis. We find that the density and temperature profiles are quite sensitive to curvature variations along the loop, even for loops with similar aspect ratios.
Mechanisms of triple-shape polymeric composites due to dual thermal transitions
Mather, Patrick T.
and fiber network) to achieve optimum control of properties. The triple-shape memory behavior demonstrated for crystallizable shape memory polymers (the fiber network) is developed to describe t-SME. The model includes memory polymers (SMPs) are a class of smart polymers that can x a temporary shape and recover
NSDL National Science Digital Library
Miss Lucherini
2007-11-10
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!!! ...
MutS mediates heteroduplex loop formation by a translocation mechanism
Dwayne J. Allen; Alexander Makhov; Michelle Grilley; John Taylor; Randy Thresher; Paul Modrich; Jack D. Griffith
1997-01-01
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, ?-shaped loop structures with the mismatch in most cases located within the DNA loop. Loop formation depends on ATP hydrolysis and loop size increases
M. Oudjene; L. Ben-Ayed; A. Delamézière; J.-L. Batoz
2009-01-01
A response surface methodology (RSM), based on Moving Least-Square (MLS) approximation and adaptive moving region of interest, is presented for shape optimization problem. To avoid a local optimum and to obtain an accurate solution at low cost, an efficient strategy which allows to improve the RSM accuracy in the vicinity of the global optimum is presented. During the progression of
Detection of periodic signal of arbitrary shape with random time delay
K. A. Ansari
1985-01-01
The detection of periodic signals of arbitrary wave shape with random time delay in additive white Gaussian noise, is a problem of practical significance in radar and communication applications. In this thesis, the analysis and design of optimum and suboptimum receivers for detecting signals as described above has been carried out. The design of optimum (in minimum probability of error,
Controller architectures for optimum performance in practical active acoustic metamaterials
Boyer, Edmond
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
Optimum testing of multiple hypotheses in quantum detection theory
NASA Technical Reports Server (NTRS)
Yuen, H. P.; Kennedy, R. S.; Lax, M.
1975-01-01
The problem of specifying the optimum quantum detector in multiple hypotheses testing is considered for application to optical communications. The quantum digital detection problem is formulated as a linear programming problem on an infinite-dimensional space. A necessary and sufficient condition is derived by the application of a general duality theorem specifying the optimum detector in terms of a set of linear operator equations and inequalities. Existence of the optimum quantum detector is also established. The optimality of commuting detection operators is discussed in some examples. The structure and performance of the optimal receiver are derived for the quantum detection of narrow-band coherent orthogonal and simplex signals. It is shown that modal photon counting is asymptotically optimum in the limit of a large signaling alphabet and that the capacity goes to infinity in the absence of a bandwidth limitation.
Optimum Algorithms for a Model of Direct Chaining
Vitter, Jeffrey Scott; Chen, Wen-Chin
1985-05-01
Direct chaining is a popular and efficient class of hashing algorithms. In this paper we study optimum algorithms among direct chaining methods, under the restrictions that the records in the hash table are not moved after ...
Mean Intensity of Sound in an Auditorium and Optimum Reverberation
Samuel Lifshitz
1926-01-01
The optimum time of reverberation was determined experimentally for the piano, the violin, the violoncello, for bass and soprano voices and human speech in a room of 260 m3. The experimental determinations (1.08-1.14 sec.) give the mean value of 1.11 sec. An earlier investigation in a smaller hall of 126 m3 gave a mean optimum time of Top=1.06 sec. It
Optimum Combining in Digital Mobile Radio with Cochannel Interference
JACK H. WINTERS
1984-01-01
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
Optimum simple step-stress accelerated life tests with censoring
D. S. Bai; M. S. Kim; S. H. Lee
1989-01-01
The authors present the optimum simple time-step and failure-step stress accelerated life tests for the case where a prespecified censoring time is involved. An exponential life distribution with a mean that is a log-linear function of stress, and a cumulative exposure model are assumed. The authors obtain the optimum test plans to minimize the asymptotic variance of the maximum-likelihood estimator
Optimum filters for narrow-band frequency modulation.
NASA Technical Reports Server (NTRS)
Shelton, R. D.
1972-01-01
The results of a computer search for the optimum type of bandpass filter for low-index angle-modulated signals are reported. The bandpass filters are discussed in terms of their low-pass prototypes. Only filter functions with constant numerators are considered. The pole locations for the optimum filters of several cases are shown in a table. The results are fairly independent of modulation index and bandwidth.
Optimum lifting body shapes in hypersonic flow at high angles of attack
V. N. Golubkin; V. V. Negoda
1995-01-01
A variational procedure for the determination of lifting body configurations having a maximum lift-to-drag ratio Kmax in hypersonic flight at high angles of attack a, is proposed. It is based on an analytical solution to the problem for three-dimensional hypersonic flow over small aspect ratio wings using thin shock-layer theory. This reduces the variational problem of finding Kmax, and the
OPTIMUM SHAPE DESIGN FOR UNSTEADY THREE-DIMENSIONAL VISCOUS FLOWS USING
Jameson, Antony
to compute the flow through a 23 blade row compressor. The overwhelming majority of the computational time in forward flight, turbomachinery blades and cooling fans operate in unsteady flow and are constantly estimates for the computational cost of a multistage compressor and turbine calculation based
NSDL National Science Digital Library
Catherine Jordan
2012-01-01
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.
Carlo Rovelli
1997-01-01
The problem of finding the quantum theory of the gravitational field, and\\u000athus understanding what is quantum spacetime, is still open. One of the most\\u000aactive of the current approaches is loop quantum gravity. Loop quantum gravity\\u000ais a mathematically well-defined, non-perturbative and background independent\\u000aquantization of general relativity, with its conventional matter couplings. The\\u000aresearch in loop quantum gravity
NSDL National Science Digital Library
2003-01-01
This interactive Java applet allows users to explore perimeter and area and the relationship between them. The activity gives irregular shapes or rectangles on a grid, and then the user enters the perimeter and area of the figure. An optional scoring feature allows users to keep track of the number correct.
Observational Evidence for Loop-Loop Interaction
NASA Astrophysics Data System (ADS)
Guiping, W.; Guangli, H.; Yuhua, T.; Aoao, X.
2004-01-01
Through analysis of the data including the hard x-ray(BASTE) microwave(NoRP) and magnetogram(MDI from SOHO) as well as the images of soft x-ray(YHKOH) and EIT(SOHO) on Apr. 151998 solar flare in the active region 8203(N30W12) we found: (1) there are similar quasi period oscillation in the profile of hard x-ray flux (25-5050-100keV) and microwave flux(1GHz) with duration of 85+/-25s every peak includes two sub-peak structures; (2) in the preheat phase of the flare active magnetic field changes apparently and a s-pole spot emerges ; (3) several EIT and soft x-ray loops exist and turn into bright . All of these may suggest that loop-loop interaction indeed exist. Through reconnection the electrons may be accelerated and the hard x-ray and microwave emission take place.
NSDL National Science Digital Library
Mr. Hoskins
2005-11-21
We will be learning the names and properties (# of sides, vertices, parallel sides, etc.) of several different geometric shapes. By now, everybody should know how many sides a square has and be able to recognize a circle. But, do you know how many vertices a parallelogram has, or how many sides to a rhombus? After completing the following exercies, you should be able to answer those questions and many ...
Optimum irradiance distribution of concentrated sunlight for photovoltaic energy conversion
NASA Astrophysics Data System (ADS)
Benítez, Pablo; Mohedano, Rubén
1999-04-01
The irradiance distribution on a concentration photovoltaic cell that produces maximum conversion efficiency has been found with the tools of Variational Calculus. The analysis is two dimensional and can be applied to a comb-like double busbar solar cell illuminated by a line-focus concentrator. The optimum distribution is, in general, nonuniform, and depends on the internal parameters of the solar cell: the higher the contribution of the grid to the global cell series resistance, the lower the uniformity of the optimum irradiance distribution. In practical cases, the efficiency for uniform illumination is close to that of the optimum, but in the latter the irradiance close to the busbar may be noticeable higher than the average.
Determining the Optimum Number of Increments in Composite Sampling
Hathaway, John E.; Schaalje, G Bruce; Gilbert, Richard O.; Pulsipher, Brent A.; Matzke, Brett D.
2008-09-30
Composite sampling can be more cost effective than simple random sampling. This paper considers how to determine the optimum number of increments to use in composite sampling. Composite sampling can be more cost effective than simple random sampling. This paper considers how to determine the optimum number of increments to use in composite sampling. Composite sampling terminology and theory are outlined and a method is developed which accounts for different sources of variation in compositing and data analysis. This method is used to define and understand the process of determining the optimum number of increments that should be used in forming a composite. The blending variance is shown to have a smaller range of possible values than previously reported when estimating the number of increments in a composite sample. Accounting for differing levels of the blending variance significantly affects the estimated number of increments.
Digital Parallel Processor Array for Optimum Path Planning
NASA Technical Reports Server (NTRS)
Kremeny, Sabrina E. (Inventor); Fossum, Eric R. (Inventor); Nixon, Robert H. (Inventor)
1996-01-01
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.
Tool Geometry for Friction Stir Welding—Optimum Shoulder Diameter
NASA Astrophysics Data System (ADS)
Mehta, M.; Arora, A.; de, A.; Debroy, T.
2011-09-01
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.
Closed-loop operation with alternative dewatering technology
Halliday, W.S.; Bray, R.P.; Youens, J.W.
1993-03-01
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.
Joselevich, Ernesto
Photoconductive CdSe Nanowire Arrays, Serpentines, and Loops Formed by Electrodeposition on Self-density straight arrays, as well as in the shape of serpentines and loops. These nanowires exhibit significant aligned arrays of hundreds of CdSe nanowires, serpentines, and loops. We show that the nanowire Cd
Hydrofoils: optimum lift-off speed for sailboats.
Baker, R M
1968-12-13
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
Optimum control forces for multibody systems with intermittent motion
NASA Technical Reports Server (NTRS)
Ider, Sitki Kemal; Amirouche, F. M. L.
1989-01-01
The objective is to address the continuity of motion when a dynamical system is suddenly subjected to constraint conditions. Motion discontinuity due to the initial constraint violation is avoided by prior control forces that adjust the motion and yield velocity and acceleration consistent at the point of application of the constraint. The optimum control forces are determined for a specified control interval. The method proposed provides an optimum adjustment of the system's motion and assures that the stresses developed at the system components are kept within acceptable limits. The procedures developed will be illustrated making use of inequality constraints applied to obstacle avoidance problems in robotics.
Optimum multisensor data fusion for image change detection
Ze-Sun Jain; Yawgeng A. Chau
1995-01-01
Optimum multisensor data fusion is addressed for image change\\u000d\\u000adetection based on the optimum likelihood ratio test for the statistical\\u000d\\u000adependence of the luminance signals in additive Gaussian noise. It is\\u000d\\u000ademonstrated that the information to be transmitted from the sensors to\\u000d\\u000athe fusion center is the maximum likelihood estimates of the correlation\\u000d\\u000acoefficients between pairs of consecutive image frames.
Self-Stabilizing Storage Loops for Magnetic-Bubble Memories
NASA Technical Reports Server (NTRS)
Nelson, Gary L.
1987-01-01
Adjacent, sinusoidal loops provide defect-tolerant, self-stabilizing structures. New technology consists of three components providing self-stabilizing structures. First, apertures positioned so bubbles propagate alternately into hexagonally related positions and directly opposed positions; addition of straight barriers by ion milling or implantation of garnet adds transverse stability but leaves longitudinally metastable postions. Second, modification of barrier to sinusoidal shape provides "energy wells" in longitudinal direction at opposed positions and eliminates metastability. Third, positioning and phasing of counterrotating storage loops, provide stable hexagonal support between adjacent loops.
NSDL National Science Digital Library
2012-06-08
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.
Variable structure control of shape memory alloy actuators
D. Grant; V. Hayward
1997-01-01
A shape memory alloy (SMA) actuator consisting of a number of thin NiTi fibers woven in a counter rotating helical pattern around supporting disks is first described. This structure accomplishes a highly efficient transformation between force and displacement overcoming the main mechanical drawback of shape memory alloys, that being limited strain. Time domain open loop experiments were then conducted to
Ghosh, Sayan; Das, Swagatam; Vasilakos, Athanasios V; Suresh, Kaushik
2012-02-01
Differential evolution (DE) is arguably one of the most powerful stochastic real-parameter optimization algorithms of current interest. Since its inception in the mid 1990s, DE has been finding many successful applications in real-world optimization problems from diverse domains of science and engineering. This paper takes a first significant step toward the convergence analysis of a canonical DE (DE/rand/1/bin) algorithm. It first deduces a time-recursive relationship for the probability density function (PDF) of the trial solutions, taking into consideration the DE-type mutation, crossover, and selection mechanisms. Then, by applying the concepts of Lyapunov stability theorems, it shows that as time approaches infinity, the PDF of the trial solutions concentrates narrowly around the global optimum of the objective function, assuming the shape of a Dirac delta distribution. Asymptotic convergence behavior of the population PDF is established by constructing a Lyapunov functional based on the PDF and showing that it monotonically decreases with time. The analysis is applicable to a class of continuous and real-valued objective functions that possesses a unique global optimum (but may have multiple local optima). Theoretical results have been substantiated with relevant computer simulations. PMID:21791412
Optimum Selection of a Composite Product System Using MADM Approach
R. T. Durai Prabhakaran; B. J. C. Babu; V. P. Agrawal
2006-01-01
The paper describes a methodology for evaluation, coding, ranking, and optimum selection of subsystems for composite product used directly by its manufacturers. This method is important from the point view of development of a reliable database, virtual design, customization, developing cutting-edge technology, and meeting the challenges of global competition in composite industry. The 77-attribute electronic coding scheme and the evaluation
Optimum design of short journal bearings by artificial life algorithm
Bo-Suk Yang; Yun-Hi Lee; Byeong-Keun Choi; Hyung-Ja Kim
2001-01-01
This paper presents an enhanced artificial life algorithm for optimum design of short journal bearing. As artificial life organisms have a sensing system, they can find the resource they want and metabolize it. The characteristics of artificial life are emergence and dynamic interaction with the environment. In other words, the micro-interaction with each other in the artificial life's group results
Biomass power cost and optimum plant size in western Canada
Amit Kumar; Jay B. Cameron; Peter C. Flynn
2003-01-01
The power cost and optimum plant size for power plants using three biomass fuels in western Canada were determined. The three fuels are biomass from agricultural residues (grain straw), whole boreal forest, and forest harvest residues from existing lumber and pulp operations (limbs and tops). Forest harvest residues have the smallest economic size, 137 MW, and the highest power cost,
Trends in mechanical fasteners. [considering optimum metric fastener system
NASA Technical Reports Server (NTRS)
Levy, J. B.
1972-01-01
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.
Improved genetic algorithms based optimum path planning for mobile robot
Soh Chin Yun; Veleppa Ganapathy; Lim Ooi Chong
2010-01-01
Improved genetic algorithms incorporate other techniques, methods or algorithms to optimize the performance of genetic algorithm. In this paper, improved genetic algorithms of optimum path planning for mobile robot navigation are proposed. An Obstacle Avoidance Algorithm (OAA) and a Distinguish Algorithm (DA) are introduced to generate the initial population in order to improve the path planning efficiency to select only
Multichannel filtering for optimum noise reduction in microphone arrays
Dinei A. Florêncio; Henrique S. Malvar
2001-01-01
Introduces an optimization criterion for the design of microphone arrays, and derives an optimum filter based on this criterion. The algorithm computes two separate correlation matrices for the signal: one for when only background noise is present, and one for when both noise and signal are present. A filter is then computed based on these matrices, optimizing the proposed weighted
Optimum Transfer Guide: Public Relations Why Study Public Relations?
Gelfond, Michael
Numbering System (TCCNS) aids students in the transfer of general academic courses between Texas public post- ed to the student's academic record. For more information on transfer course equivalenciesOptimum Transfer Guide: Public Relations Why Study Public Relations? The Public Relations
Modeling the Miocene climatic optimum: Ocean circulation N. Herold,1
Müller, Dietmar
Modeling the Miocene climatic optimum: Ocean circulation N. Herold,1 M. Huber,2 R. D. Müller,1) forced with early to middle Miocene ($2014 Ma) topography, bathymetry, vegetation and modern CO2 is weaker in the Miocene due to weaker midlatitude westerlies in the southern hemisphere, caused by lowering
Mercury/Waterfilling: Optimum Power Allocation with Arbitrary Input Constellations
Verdú, Sergio
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
OPTIMUM CONTROL OF OSCILLATION OF WAVE-ENERGY CONVERTERS
J. Falnes
1993-01-01
The power output from wave energy converters (WECs) may be increased by controlling the oscillation in order to approach an optimum interaction between the WEC and the incident wave. Optimally controlled WECs, designed to operate at full capacity a rather large fraction of their lifetime, may improve the economic prospects for wave power significantly. Most of the WECs discussed here,
Optimum pulse filters for radiation detectors and their parameters
L. S. Gorn; M. V. Iovlev; B. I. Khazanov
1972-01-01
ABS>Calculations are given for the parameters of optimum pulse filters ; for radiation detection instruments. These filters guarantee minimum statistical ; measurement error at a given density function of the distribution of useful and ; back-round signals and signal frequency ratio. A equations are derived for the ; coefficient of reduction of the pulse frequency in the zone of filter
Improved global sea surface temperature analyses using optimum interpolation
Richard W. Reynolds; Thomas M. Smith
1994-01-01
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
Optimum stuff threshold modulation schemes for digital data transmission
Suman S. Abeysekera
1994-01-01
The method of `stuff threshold modulation' (STM) is widely used with pulse stuffing in network synchronizers to obtain reduced jitter power at the output of desynchronizers. Of the various STM waveforms that appear in the published literature, none have been selected as an optimum for a given set of synchronizer-desynchronizer operating conditions. This paper formulates the problem of STM waveform
Optimum Power and Rate Allocation for Coded Victoria Kostina
Loyka, Sergey
) system, spatial mul- tiplexing, coded V-BLAST, power/rate allocation, waterfilling, performance analysis], consider rate allocation. Most practical communication systems use coding; uncoded systems are rareOptimum Power and Rate Allocation for Coded V-BLAST Victoria Kostina Department of Electrical
Optimum Treatment Allocation in Clinical Trials Using Heteroscedastic Linear Models
New York at Stoney Brook, State University of
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 treatment to treatment. This paper discusses the optimal treatment allocation scheme in this situ ation
Optimum length of finned pipe for waste heat recovery
M. S. Söylemez
2008-01-01
A thermoeconomic feasibility analysis is presented yielding a simple algebraic optimization formula for estimating the optimum length of a finned pipe that is used for waste heat recovery. A simple economic optimization method is used in the present study by combining it with an integrated overall heat balance method based on fin effectiveness for calculating the maximum savings from a
Optimum displacement for compound image generation in medical ultrasound
M. O'Donnell; S. D. Silverstein
1988-01-01
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
Optimum detection and receiver performance for multistatic radar configurations
D. Baumgarten
1982-01-01
The binary detection problem is investigated for a multistatic radar configuration with one transmitter and N separated receivers, A time-discrete mathematical framework is developed to which the likelihood ratio test can be applied. The optimum multistatic receiver structures are elaborated for the Swerling fluctuation models and can be described as follows: Each wave form is fed into a square envelope
QUADRUPED OPTIMUM GAITS ANALYSIS FOR PLANETARY EXPLORATION Ioannis Kontolatis (1)
Papadopoulos, Evangelos
QUADRUPED OPTIMUM GAITS ANALYSIS FOR PLANETARY EXPLORATION Ioannis Kontolatis (1) , Dimitrios on the performance and gait characteristics of a quadruped robot. This paper presents results obtained using a planar quadruped robot gaits. In addition, an optimization procedure using either MathWorks fmincon
Optimum number of hops in linear multihop wireless networks
Rajan, Dinesh
Optimum number of hops in linear multihop wireless networks Dinesh Rajan Department of Electrical and a total network power constraint. We characterize the optimal number of hops that achieves maximum end-to-end throughput. In one special case, we derive an analytical expression for this optimal number of hops and show
Robust optimum criteria for tuned mass dampers in fuzzy environments
Giuseppe Carlo Marano; Giuseppe Quaranta
2009-01-01
Tuned mass dampers are widely adopted passive strategies for vibrations mitigation, in the past years extensively investigated to improve the offered protection level in any mechanical systems in which they are installed. Although different mechanical and energetic optimum criteria have been proposed in the last decades by assuming involved parameters as deterministically known, nowadays the need persists to explore more
Optimum Onager: The Classical Mechanics of a Classical Siege Engine
ERIC Educational Resources Information Center
Denny, Mark
2009-01-01
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…
NASA Technical Reports Server (NTRS)
Gottschlich, Joseph M.; Richter, Robert
1991-01-01
The concept of a thermal power loop (TPL) to transport thermal power over relatively large distances is presented as an alternative to heat pipes and their derivatives. The TPL is compared to heat pipes, and capillary pumped loops with respect to size, weight, conservation of thermal potential, start-up, and 1-g testing capability. Test results from a proof of feasibility demonstrator at the NASA JPL are discussed. This analysis demonstrates that the development of specific thermal power loops will result in substantial weight and cost savings for many spacecraft.
Kolowith, R.; Owen, T.J.; Berg, J.D.; Atwood, J.M.
1981-10-01
An engineering design and operating experience of a large, isothermal, lithium-coolant test loop are presented. This liquid metal coolant loop is called the Experimental Lithium System (ELS) and has operated safely and reliably for over 6500 hours through September 1981. The loop is used for full-scale testing of components for the Fusion Materials Irradiation Test (FMIT) Facility. Main system parameters include coolant temperatures to 430/sup 0/C and flow to 0.038 m/sup 3//s (600 gal/min). Performance of the main pump, vacuum system, and control system is discussed. Unique test capabilities of the ELS are also discussed.
Jose M. G. Vilar; Leonor Saiz
2006-06-19
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.
Holographic calculations of Euclidean Wilson loop correlator in Euclidean anti-de Sitter space
NASA Astrophysics Data System (ADS)
Ziama, Sannah
2015-04-01
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.
Physical Meaning of the Optimum Measurement Process in Quantum Detection Theory
NASA Technical Reports Server (NTRS)
Osaki, Masao; Kozuka, Haruhisa; Hirota, Osamu
1996-01-01
The optimum measurement processes are represented as the optimum detection operators in the quantum detection theory. The error probability by the optimum detection operators goes beyond the standard quantum limit automatically. However the optimum detection operators are given by pure mathematical descriptions. In order to realize a communication system overcoming the standard quantum limit, we try to give the physical meaning of the optimum detection operators.
NASA Technical Reports Server (NTRS)
Emslie, A. Gordon
1989-01-01
The somewhat questionable concept of an isolated flare loop and the various physical mechanisms believed to be responsible, to some degree, for energy transport within the loop structure is reviewed. Observational evidence suggests a predominant role for high-energy electrons as an energy transport mechanism, and the consequences of such a scenario is explored in some detail, focusing on radiation signatures in the soft X-ray, hard X-ray, and EUV wavebands, as observed by recent satellite observatories. It is found that the predictions of flare loop models are in fact in excellent agreement with these observations, reinforcing both the notion of the loop as a fundamental component of solar flares and the belief that electron acceleration is an integral part of the flare energy release process.
Cosmic string loop microlensing
Chernoff, David F.
Cosmic superstring loops within the galaxy microlens background point sources lying close to the observer-string line of sight. For suitable alignments, multiple paths coexist and the (achromatic) flux enhancement is a ...
Laura Finzi
DNA looping is a ubiquitous regulatorymechanism which can be involved in DNA transcription, ecombination, repair, etc. Here,\\u000a I will focus on protein-mediated DNA looping as a mechanism of tran-scriptional regulation. Indeed, such topological change\\u000a in DNA is known to repress and\\/or activate many prokaryotic and viral genes [1–4] and is believed to mediate interaction between\\u000a promoters and enhancers as well
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
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.
Gianluca Grignani; Joanna L. Karczmarek; Gordon W. Semenoff
2009-06-03
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^3. It occurs for large completely symmetric representation of the SU(N) symmetry group. We speculate that this transition is reflected in the string theory dual as a critical behavior of the D3-brane duals of large representation loops.
NASA Technical Reports Server (NTRS)
Klimchuk, James A.; Karpen, Judy T.; Patsourakos, Spiros
2008-01-01
One of the great mysteries of coronal physics that has come to light in the last few years is the discovery that warn (- 1 INK) coronal loops are much denser than expected for quasi-static equilibrium. Both the excess densities and relatively long lifetimes of the loops can be explained with bundles of unresolved strands that are heated impulsively to very high temperatures. Since neighboring strands are at different stages of cooling, the composite loop bundle is multi-thermal, with the distribution of temperatures depending on the details of the "nanoflare storm." Emission hotter than 2 MK is predicted, but it is not clear that such emission is always observed. We consider two possible explanations for the existence of over-dense warm loops without corresponding hot emission: (1) loops are bundles of nanoflare heated strands, but a significant fraction of the nanoflare energy takes the form of a nonthermal electron beam rather then direct plasma heating; (2) loops are bundles of strands that undergo thermal nonequilibrium that results when steady heating is sufficiently concentrated near the footpoints. We present numerical hydro simulations of both of these possibilities and explore the observational consequences, including the production of hard X-ray emission and absorption by cool material in the corona.
Feng, Xin; Tong, Yiying
2013-08-01
We present a method for computing "choking" loops--a set of surface loops that describe the narrowing of the volumes inside/outside of the surface and extend the notion of surface homology and homotopy loops. The intuition behind their definition is that a choking loop represents the region where an offset of the original surface would get pinched. Our generalized loops naturally include the usual 2g handles/tunnels computed based on the topology of the genus-g surface, but also include loops that identify chokepoints or bottlenecks, i.e., boundaries of small membranes separating the inside or outside volume of the surface into disconnected regions. Our definition is based on persistent homology theory, which gives a measure to topological structures, thus providing resilience to noise and a well-defined way to determine topological feature size. More precisely, the persistence computed here is based on the lower star filtration of the interior or exterior 3D domain with the distance field to the surface being the associated 3D Morse function. PMID:23744260
A high-performance hysteresis loop tracer
NASA Astrophysics Data System (ADS)
Kulik, Tadeusz; Savage, Howard T.; Hernando, Antonio
1993-05-01
A high-performance and inexpensive hysteresis loop tracer has been developed to measure quasistatic (0.02 Hz or less) hysteresis loops of soft ferromagnetic materials. It was applied very successfully to measure straight pieces of amorphous and nanocrystalline ribbons and amorphous wires. Especially high-magnetic-field resolution is required when nanocrystalline ferromagnets and amorphous wires are measured. Nanocrystalline materials exhibit very low coercivity (Hc=0.1-0.5 A/m). The error of Hc measurement using this tracer does not exceed 0.05 A/m even though the amorphous wires have very small cross section (0.008 mm2). The examples of hysteresis loops measured at low (50 A/m) and high magnetic field (14 kA/m) are presented. The apparatus consists of an IBM-compatible computer equipped with 12 bit analog-to-digital and digital-to-analog converters, bipolar power supply, fluxmeter, solenoid and a pickup coil connected to a compensation coil. This equipment is free of 50 Hz noise, a significant problem in the performance of low-frequency loop tracers. The software was developed to enable measurement and immediate display of the M-H hysteresis loop. Previous loops also can be displayed and printed. Calibration of the setup is also possible. In the case of straight samples the measurements are followed by calculation of demagnetization factor Nd(calc.) using the ellipsoidal approximation of the sample shape. It was found that the experimental value of Nd is 30%-40% of the calculated value Nd(calc.) for the ribbons studied. Higher values of Nd correspond to the thicker ribbons where better agreement was obtained.
The Holocene Thermal Optimum in the Barents Sea
NASA Astrophysics Data System (ADS)
Murdmaa, I.; Ivanova, E.; Risebrobakken, B.; Akhrimenko, N.; Yamskova, E.
2005-12-01
AMS 14C-dated oxygen isotope records on planktic and benthic foraminifer in our Core ASV 880 from the eastern branch of the Franz Victoria Trough (Northern Barents Sea) shows the Holocene thermal optimum at 7.8 - 6.9 cal ka BP (Duplessy et al., 2001) manifested by low oxygen isotope values as a result of warming of subsurface to bottom waters related to the increased Atlantic water input. Benthic foraminiferal assemblages during this optimum are enriched in the species indicating rather long ice-free season. We test here a hypothesis that the optimum can also be identified by foraminiferal assemblages in other parts of the sea with present water column structure indicating subsurface Atlantic water. We studied the Holocene benthic and planktic foraminiferal assemblages at several locations within the passage of the Atlantic water in surface and subsurface layers,and tried to identify the timing of assumed optimum by the interpolation between AMS 14C-dates when available, and using a level of polychaetas appearance in the Barents Sea at about 5 cal ka BP. The base of the Holocene layer is legibly distinguished in our cores by pronounced changes in sediment color, grain size, sedimentary structures, and an appearance of numerous foraminiferal tests. These two levels provide us with the tick-points for the age control in undated cores. An increase in abundance of species related to Atlantic-derived water is found at the end of Early Holocene in the south-western branch of the Franz Victoria Trough, whereas any faunal indication of the optimum are absent in other cores. On the contrary, our new oxygen isotope data clearly demonstrate the optimum at some locations. The maximum content of so-called "atlantic" benthic species occurs at different time levels in specific cores, and the same is true for planktic foraminifers generally considered to be related to the Atlantic water in the Barents Sea. Therefore, the above hypothesis is not confirmed by our data. It means that besides the water mass properties foraminifer distribution in the region is strongly controlled by food supply.
Superordinate Shape Classification Using Natural Shape Statistics
ERIC Educational Resources Information Center
Wilder, John; Feldman, Jacob; Singh, Manish
2011-01-01
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…
Superordinate shape classification using natural shape statistics
Wilder, John; Feldman, Jacob; Singh, Manish
2011-01-01
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 class, seeking shape statistics that effectively discriminated the classes. We conducted two experiments in which human subjects were asked to classify novel shapes into the same natural classes. We compared subjects’ classifications to those of a naive Bayesian classifier based on the natural shape statistics, and found good agreement. We conclude that human superordinate shape classifications can be well understood as involving a simple statistical classification of the shape skeleton that has been “tuned” to the natural statistics of shape. PMID:21440250
General solutions of optimum problems in nonstationary flight
NASA Technical Reports Server (NTRS)
Miele, Angelo
1955-01-01
A general method concerning optimum problems in nonstationary flight is developed and discussed. Best flight techniques are determined for the following conditions: climb with minimum time, climb with minimum fuel consumption, steepest climb, descending and gliding flight with maximum time or with maximum distance. Optimum distributions of speed with altitude are derived assuming constant airplane weight and neglecting curvatures and squares of path inclination in the projection of the equation of motion on the normal to the flight path. The results of this paper differ from the well-known results obtained by neglecting accelerations with one exception, namely the case of gliding with maximum range. The paper is concluded with criticisms and remarks concerning the physical nature of the solutions and their usefulness for practical applications.
A Model for Constrained Optimum Water Pricing and Capacity Expansion
NASA Astrophysics Data System (ADS)
Dandy, G. C.; McBean, E. A.; Hutchinson, B. G.
1984-05-01
Previous studies of optimum water pricing and capacity expansion have ignored the political and administrative factors which limit the range of feasible decisions. A general model is presented for identifying the water price horizon so as to maximize the present value of net benefits. Constraints on the range of water price, the rate of price change, and financial cost recovery are included in the model. The model is applied to a hypothetical case study of an urban water supply system. The results indicate that optimum water pricing and capacity expansion policies are likely to achieve some increase in economic benefits when compared with average cost pricing. Administrative and political constraints tend to reduce these benefits but result in more acceptable pricing policies.
Sha, Edwin
be used to reduce the cost of loop bound testing. Loop fusion can also be used to exploit the instruction-level parallelism on the modern high- performance architecture such as VLIW [1, 8]. Loop fusion can enhance the data the instruction-level parallelism and enhance data locality [1, 3, 5, 8]. In [3], Kennedy and McKinley use loop fu
Numerical characterization of dynamic hysteresis loops and losses in soft magnetic materials
E. Cardeffi; Romano Giannetti; Bernardo Tellini
2005-01-01
This paper deals with the characterization of dynamic loops shapes and losses in soft magnetic materials. An experimental and theoretical analysis has been done in order to describe static and dynamic hysteresis on soft ferrite cores. A parallelogram-loop-based hysteresis modeling is described and discussed. The possibility of the model to include vector hysteresis and the related properties are then discussed,
Development and application of optimum sensitivity analysis of structures
NASA Technical Reports Server (NTRS)
Barthelemy, J. F. M.; Hallauer, W. L., Jr.
1984-01-01
The research focused on developing an algorithm applying optimum sensitivity analysis for multilevel optimization. The research efforts have been devoted to assisting NASA Langley's Interdisciplinary Research Office (IRO) in the development of a mature methodology for a multilevel approach to the design of complex (large and multidisciplinary) engineering systems. An effort was undertaken to identify promising multilevel optimization algorithms. In the current reporting period, the computer program generating baseline single level solutions was completed and tested out.
Optimum design of Nd-doped fiber optical amplifiers
T. Rasmussen; A. Bjarklev; O. Lumholt; M. Obro; B. Pedersen; J. H. Povlsen; K. Rottwitt
1992-01-01
The waveguide parameters for a Nd-doped fluoride (Nd:ZBLANP) fiber amplifier have been optimized for small-signal and booster operation using an accurate numerical model. The optimum cutoff wavelength is shown to be 800 nm and the numerical aperture should be made as large as possible. Around 80% booster quantum conversion efficiency can be reached for an input power of 10 dBm
The Population of Small Comets: Optimum Techniques for Detection
NASA Technical Reports Server (NTRS)
Schleicher, D.; AHearn, M.; Stewart, I. A. F.; Randall, C.; Brandt, J.
1999-01-01
The goals of this project were: (1) to present evidence to the scientific community for the importance of the small comet population and (2) to develop techniques for optimum detection in order to characterize the population. The work has been carried out by D. Schleicher (Lowell Observatory), M. A'Hearn and Y. Fernandez (University of Maryland), I.A.F. Stewart, C. Randall, and J. Brandt (University of Colorado).
OPTIMUM DAMPING IN A NON-LINEAR BASE ISOLATION SYSTEM
R. S. Jangid
1996-01-01
Optimum isolation damping for minimum acceleration of a base-isolated structure subjected to earthquake ground excitation is investigated. The stochastic model of theEl-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
OPTIMUM MODAL CHARACTERISTICS FOR MULTISTORY BUILDINGS ISOLATED WITH LRBS
Abdolrahim Jalali; Peyman Narjabadifam
Improving the performance of available base-isolation technologies in conjunction with optimum using of dynamic properties of superstructure such as stiffness, damping and mass has gained lot of interests in the earthquake engineering field. In this study, the effect of superstructure characteristics on performance of multi-story buildings isolated with lead-plug laminated rubber bearings has been investigated. The superstructure characteristics considered at
The Population of Small Comets: Optimum Techniques for Detection
NASA Technical Reports Server (NTRS)
Brandt, John C.
1997-01-01
The goals of this project were: (1) to present evidence to the scientific community for the importance of the small comet population and (2) to develop techniques for optimum detection in order to characterize the population. Our work on techniques has been to develop algorithms for searching images for SCs based on the distinctive properties of comets; (1) motion with respect to background stars; (2) extended source with most light coming from the coma rather than the nucleus; and characteristic spectral signature.
A criterion for optimum adhesion applied to fibre reinforced composites
M. CONNOR; J.-E BIDAUX; J.-A. E MANSON
1997-01-01
The effects of physical adhesion on the mechanical properties of a composite structure are examined in this work. A criterion\\u000a for optimum adhesion between matrix and reinforcing fibres is proposed based on maximizing the wetting tension. It is shown\\u000a that the maximum wetting tension criterion best fulfils two important requirements for a strong interface:(i) the physical\\u000a interactions at the molecular
Optimum filters and their tolerance for nonlinear satellite channels
S. Murakami; Y. Furuya; S. Otani; Y. Tanimoto
1981-01-01
An optimum filtering system is examined for nonlinear one-hop digital satellite channels, where channel spacings are 1.3\\/T (the Intelsat narrow-band model) and 2.3\\/T (a typical wideband model). For each channel model, transmitter and receiver filters are optimized so as to yield minimum bit error rate at 10 dB input back-off for an earth station high-power amplifier and 2 dB for
Optimum protein-excipient interactions using molecular docking simulations
Tarar, Haider
2014-04-01
on the protein. Excipients are inactive ingredients in the drug product that help hold a dose of the active pharmaceutical ingredient (API) together and keep it stable for a long shelf life (Ritter, 2008). Hot spots are aggregation-prone regions on a...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...
Optimum soft-output detection for channels with intersymbol interference
Yunxin Li; Branka Vucetic; Yoichi Sato
1995-01-01
In contrast to the conventional Viterbi algorithm (VA) which generates hard-outputs, an optimum soft-output algorithm (OSA) is derived under the constraint of fixed decision delay for detection of M-ary digital signals in the presence of intersymbol interference and additive white Gaussian noise. The OSA, a new type of the conventional symbol-by-symbol maximum a posteriori probability algorithm, requires only a forward
Optimum combining of residual carrier array signals in correlated noises
NASA Technical Reports Server (NTRS)
Liang, R.; Suen, P. H.; Tan, H. H.
1996-01-01
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.
Optimum Waveforms for Differential Ion Mobility Spectrometry (FAIMS)
Shvartsburg, Alexandre A.; Smith, Richard D.
2009-01-01
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
Optimum Damping in a Non-Linear Base Isolation System
NASA Astrophysics Data System (ADS)
Jangid, R. S.
1996-02-01
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.
Null Zig-Zag Wilson Loops in N=4 SYM
Xie, Zhifeng
2009-01-01
In planar ${\\cal N}=4$ supersymmetric Yang-Mills theory we have studied supersymmetric Wilson loops composed of a large number of light-like segments, i.e., null zig-zags. These contours oscillate around smooth underlying spacelike paths. At one-loop in perturbation theory we have compared the finite part of the expectation value of null zig-zags to the finite part of the expectation value of non-scalar-coupled Wilson loops whose contours are the underlying smooth spacelike paths. In arXiv:0710.1060 [hep-th] it was argued that these quantities are equal for the case of a rectangular Wilson loop. Here we present a modest extension of this result to zig-zags of circular shape and zig-zags following non-parallel, disconnected line segments and show analytically that the one-loop finite part is indeed that given by the smooth spacelike Wilson loop without coupling to scalars which the zig-zag contour approximates. We make some comments regarding the generalization to arbitrary shapes.
NASA Astrophysics Data System (ADS)
Bak, Jun-Gyo; Lee, Sang-Gon; Ka, Eun-Mie
2007-11-01
Three sets of diamagnetic loop (DL), at different locations, are designed to measure diamagnetic flux during a plasma discharge in the KSTAR machine. Each set consists of two concentric poloidal loops, and it is used for the diamagnetic flux measurement with the compensation of a ripple from to the power supply producing a toroidal field and a pick-up signal from the poloidal field due to the misalignment in the installation. One set is installed on inner wall of the vacuum vessel for the flux measurement at the first plasma in the KSTAR machine. It is located at a toroidal angle in the vacuum vessel, and the gap distance between inner and outer loops is 2 cm. An accurate position measurement of the two loops is done by using a laser tracker system after the installation. The in-situ calibration of the loops is done from the toroidal flux measurement. In the measurement, the electric current of less than 100A is applied to the toroidal field coils. In this work, present status of the DL for the initial measurement in the KSTAR machine will be presented.
The gluon beam function at two loops
NASA Astrophysics Data System (ADS)
Gaunt, Jonathan R.; Stahlhofen, Maximilian; Tackmann, Frank J.
2014-08-01
The virtuality-dependent beam function is a universal ingredient in the resummation for observables probing the virtuality of incoming partons, including N -jettiness and beam thrust. We compute the gluon beam function at two-loop order. Together with our previous results for the two-loop quark beam function, this completes the full set of virtuality-dependent beam functions at next-to-next-to-leading order (NNLO). Our results are required to account for all collinear initial-state radiation effects on the N -jettiness event shape through N3LL order. We present numerical results for both the quark and gluon beam functions up to NNLO and N3LL order. Numerically, the NNLO matching corrections are important. They reduce the residual matching scale dependence in the resummed beam function by about a factor of two.
Real-time visual loop-closure detection
Adrien Angeli; Stéphane Doncieux; Jean-arcady Meyer; David Filliat
2008-01-01
In robotic applications of visual simultaneous localization and mapping, loop-closure detection and global localization are two issues that require the capacity to recognize a previously visited place from current camera measurements. We present an online method that makes it possible to detect when an image comes from an already perceived scene using local shape information. Our approach extends the bag
Two Bridges Formation on the Navajo Loop Trail
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...
Plasma shape experiments for an optimized tokamak
Hyatt, A.W.; Osborne, T.H. [General Atomics, San Diego, CA (United States); Lazarus, E.A. [Oak Ridge National Lab., TN (United States)
1994-07-01
In this paper we present results from recent experiments at DIII-D which measured the plasma stability and confinement performance product, {beta}{tau}{sub E}, in one previously studied and three new plasma shapes. One important goal of these experiments was to identify performance vs shape trends which would identify a shape compatible with both high performance and the planned effort to decrease the power flux to the divertor floor using a closed ``slot`` divertor geometry. power flux to the divertor floor using a closed ``slot`` divertor geometry. The closed divertor hardware must be designed for a reduced set of plasma shapes, so care must be taken to choose the shape that optimizes {beta}{tau}{sub E} and divertor performance. The four shapes studied form a matrix of moderate and high elongations ({kappa} {congruent} 1.8 and 2.1) and low and high triangularities ({delta} {congruent} 0.3 and 0.9). All configurations were double-null diverted (DND), held fixed during a shot, with neutral beam heating. The shapes span a range of X-point locations compatible with the envisioned closed divertor. We find that from shape to shape, a shot`s transient normalized performance, {beta}{sub N}H, where {beta}{sub N} {equivalent_to} {beta}/(I{sup p})/aB{sub T} and H {equivalent_to} {tau}{sub E}/{tau}{sub E}{sup ITER-89P}, increases strongly with triangularity, but depends only weakly on elongation. However, the normalized performance during quasi stationary ELMing H-mode, to which these discharges eventually relax, is insensitive to both triangularity and elongation. The moderate elongation, high triangularity DND shape is shown to be near optimum for future studies on DIII-D.
Feng, Xiao-gui; He, Qian-ge; Wang, Jian-chen; Chen, Jing
2014-11-01
In the application of liquid scintillation counting (LSC), the ?/? discrimination is carried out with the function of pulse shape analysis (PSA), which requires the setting of the optimum PSA level. The optimum PSA are usually determined by the generation of cross-over plots, whereby a pair of vials, one containing a pure ? emitter and the other a pure ? emitter, is counted. However, in some cases such as the determination of (237)Np/(233)Pa, a pure ? emitter or a pure ? emitter is not available. Therefore, we have developed a new approach to set the optimum PSA by measuring the sample itself of mixed ?/? emitters. The count rate of the sample in the ?-multi-channel analyzer changes monotonically with the increase of the PSA, and there is always an inflection point which is related to the optimum PSA. By fitting the data near the inflection point with the function y=ax(3)+bx(2)+cx+d, we can obtain the optimum PSA as -b/(3a), which can be used to determine the radioactivity of (237)Np/(233)Pa. The results obtained with this new approach were in good agreement with those obtained by HPGe ? spectrometry that was calibrated with an LSC sample of (237)Np/(233)Pa under a radioactive secular equilibrium. The new approach is promising to be used in simultaneous determination of gross ? and ? emitters, especially in the absence of a pure ? or ? emitter. PMID:24582116
T. W. Brown
2008-05-07
We consider the one-loop two-point function for multi-trace operators in the U(2) sector of \\cN=4 supersymmetric Yang-Mills at finite N. We derive an expression for it in terms of U(N) and S_{n+1} group theory data, where n is the length of the operators. The Clebsch-Gordan operators constructed in 0711.0176, which are diagonal at tree level, only mix at one loop if you can reach the same (n+1)-box Young diagram by adding a single box to each of the n-box Young diagrams of their U(N) representations (which organise their multi-trace structure). Similar results are expected for higher loops and for other sectors of the global symmetry group.
A complete procedure for the design and optimization of arbitrarily shaped integrated lens antennas
R. Sauleau; B. Bares
2006-01-01
This paper proposes a new design methodology of arbitrarily shaped integrated lens antennas (ILAs). First, we describe the design principles and numerical techniques of the optimization iterative loop. The starting lens shape, deduced from a general synthesis method based on geometrical optics principles, is optimized so that the radiation pattern of the ILA complies with an arbitrary amplitude-shaped template. The
Closed loop mechanical ventilation.
Wysocki, Marc; Jouvet, Philippe; Jaber, Samir
2014-02-01
Mechanical ventilation is a sophisticated technique with very narrow therapeutic ranges i.e. highly efficient and able to keep alive the most severe patients, but with considerable side effects and unwanted complications if not properly and timely used. Computerized protocols, closed loop systems, decision support, all terms which need to be defined, may help making mechanical ventilation safer and more efficient. The present paper will provide a short overview on technical and engineering considerations regarding closed loop controlled ventilation as well as tangible clinical evidences supporting the previous statement. PMID:23564277
On Modeling Morphogenesis of the Looping Heart Following Mechanical Perturbations
Ramasubramanian, Ashok; Nerurkar, Nandan L.; Achtien, Kate H.; Filas, Benjamin A.; Voronov, Dmitry A.; Taber, Larry A.
2008-01-01
Looping is a crucial early phase during heart development, as the initially straight heart tube (HT) deforms into a curved tube to lay out the basic plan of the mature heart. This paper focuses on the first phase of looping, called c-looping, when the HT bends ventrally and twists dextrally (rightward) to create a c-shaped tube. Previous research has shown that bending is an intrinsic process, while dextral torsion is likely caused by external forces acting on the heart. However, the specific mechanisms that drive and regulate looping are not yet completely understood. Here, we present new experimental data and finite element models to help define these mechanisms for the torsional component of c-looping. First, with regions of growth and contraction specified according to experiments on chick embryos, a three-dimensional model exhibits morphogenetic deformation consistent with observations for normal looping. Next, the model is tested further using experiments in which looping is perturbed by removing structures that exert forces on the heart — a membrane (splanchnopleure, SPL) that presses against the ventral surface of the heart and the left and right primitive atria. In all cases, the model predicts the correct qualitative behavior. Finally, a two-dimensional model of the HT cross section is used to study a feedback mechanism for stress-based regulation of looping. The model is tested using experiments in which the SPL is removed before, during, and after c-looping. In each simulation, the model predicts the correct response. Hence, these models provide new insight into the mechanical mechanisms that drive and regulate cardiac looping. PMID:19045547
Screening actuator locations for static shape control
NASA Technical Reports Server (NTRS)
Haftka, Raphael T.
1990-01-01
Correction of shape distortion due to zero-mean normally distributed errors in structural sizes which are random variables is examined. A bound on the maximum improvement in the expected value of the root-mean-square shape error is obtained. The shape correction associated with the optimal actuators is also characterized. An actuator effectiveness index is developed and shown to be helpful in screening actuator locations in the structure. The results are specialized to a simple form for truss structures composed of nominally identical members. The bound and effectiveness index are tested on a 55-m radiometer antenna truss structure. It is found that previously obtained results for optimum actuators had a performance close to the bound obtained here. Furthermore, the actuators associated with the optimum design are shown to have high effectiveness indices. Since only a small fraction of truss elements tend to have high effectiveness indices, the proposed screening procedure can greatly reduce the number of truss members that need to be considered as actuator sites.
The Role of Entropic Effects on DNA Loop Formation
NASA Astrophysics Data System (ADS)
Wilson, David; Tkachenko, Alexei; Lillian, Todd; Perkins, Noel; Meiners, Jens Christian
2009-03-01
The formation of protein mediated DNA loops often regulates gene expression. Typically, a protein is simultaneously bound to two DNA operator sites. An example is the lactose repressor which binds to the Lac operon of E. coli. We characterize the mechanics of this system by calculating the free energy cost of loop formation. We construct a Hamiltonian that describes the change in DNA bending energy due to linear perturbations about the looped and open states, starting from a non-linear mechanical rod model that determines the shape and bending energy of the inter-operator DNA loop while capturing the intrinsic curvature and sequence-dependent elasticity of the DNA. The crystal structure of the LacI protein provides the boundary conditions for the DNA. We then calculate normal modes of the open and closed loops to account for the thermal fluctuations. The ratio of determinants of the two Hamiltonians yields the partition function, and the enthalphic and entropic cost of looping. This calculation goes beyond standard elastic energy models because it fully accounts for the substantial entropic differences between the two states. It also includes effects of sequence dependent curvature and stiffness and allows anisotropic variations in persistence length. From the free energy we then calculate the J-factor and ratio of loop lifetimes.
A Generalized Theory of DNA Looping and Cyclization
NASA Astrophysics Data System (ADS)
Wilson, David; Lillian, Todd; Perkins, Noel; Tkachenko, Alexei; Meiners, Jens-Christian
2010-03-01
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.
NASA Astrophysics Data System (ADS)
Rovelli, Carlo
1998-04-01
The problem of finding the quantum theory of the gravitational field, and thus understanding what is quantum spacetime, is still open. One of the most active of the current approaches is loop quantum gravity. Loop quantum gravity is a non-perturbative and background independent quantization of general relativity, with its conventional matter couplings. The research in loop quantum gravity forms today a vast area, ranging from mathematical foundations to physical applications. Among the most significative results obtained are: (i) The computation of the physical spectra of geometrical quantities such as area and volume; which yields quantitative predictions on Planck-scale physics. (ii) A derivation of the Bekenstein-Hawking black hole entropy formula. (iii) An intriguing physical picture of the microstructure of quantum physical space, characterized by a polymer-like Planck scale discreteness. This discreteness emerges naturally from the quantum theory and provides a mathematically well-defined realization of Wheeler's intuition of a spacetime ``foam''. Long standing open problems within the approach (lack of a scalar product, overcompleteness of the loop basis, implementation of reality conditions) have been fully solved. The weak part of the approach is the treatment of the dynamics: at present there exist several proposals, which are intensely debated. I will provide an overview of ideas, techniques, results and open problems of this candidate theory of quantum gravity.
NASA Astrophysics Data System (ADS)
Rovelli, Carlo
1998-01-01
The problem of finding the quantum theory of the gravitational field, and thus understanding what is quantum spacetime, is still open. One of the most active of the current approaches is loop quantum gravity. Loop quantum gravity is a mathematically well-defined, non-perturbative and background independent quantization of general relativity, with its conventional matter couplings. Research in loop quantum gravity today forms a vast area, ranging from mathematical foundations to physical applications. Among the most significant results obtained are: (i) The computation of the physical spectra of geometrical quantities such as area and volume, which yields quantitative predictions on Planck-scale physics. (ii) A derivation of the Bekenstein-Hawking black hole entropy formula. (iii) An intriguing physical picture of the microstructure of quantum physical space, characterized by a polymer-like Planck scale discreteness. This discreteness emerges naturally from the quantum theory and provides a mathematically well-defined realization of Wheeler's intuition of a spacetime ``foam''. Long standing open problems within the approach (lack of a scalar product, over-completeness of the loop basis, implementation of reality conditions) have been fully solved. The weak part of the approach is the treatment of the dynamics: at present there exist several proposals, which are intensely debated. Here, I provide a general overview of ideas, techniques, results and open problems of this candidate theory of quantum gravity, and a guide to the relevant literature.
John R. Allen; Ken Kennedy
1984-01-01
Parallel and vector machines are becoming increasingly important to many computation intensive applications. Effectively utilizing such architectures, particularly from sequential languages such as Fortran, has demanded increasingly sophisticated compilers. In general, a compiler needs to significantly reorder a program in order to generate code optimal for a specific architecture.Because DO loops typically control the execution of a number of statements,
NETL - Chemical Looping Reactor
None
2014-06-26
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.
Yu. F. Maydanik
2005-01-01
Loop heat pipes (LHPs) are two-phase heat-transfer devices with capillary pumping of a working fluid. They possess all the main advantages of conventional heat pipes, but owing to the original design and special properties of the capillary structure are capable of transferring heat efficiency for distances up to several meters at any orientation in the gravity field, or to several
ERIC Educational Resources Information Center
California Integrated Waste Management Board, Sacramento.
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)…
NETL - Chemical Looping Reactor
None
2013-07-24
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.
Temporal Resolution [Loop Search
Fisher, Michael
perform the following steps. 1. Transform A into SNF, giving a set of clauses AS. 2. Perform step Logic [TEMPORAL RESOLUTION: LOOP SEARCH] Â 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
Adaptive shaping of femtosecond polarization profiles
NASA Astrophysics Data System (ADS)
Brixner, T.; Damrauer, N. H.; Krampert, G.; Niklaus, P.; Gerber, G.
2003-05-01
We report the experimental implementation of femtosecond polarization pulse shaping within an adaptive learning loop. This technique makes it possible to optimally and automatically generate light fields in which intensity, momentary frequency, and light polarization (i.e., ellipticity and orientation) change as a function of time within a single femtosecond laser pulse. By use of second-harmonic generation as a feedback signal in an evolutionary algorithm, specific phase- and polarization-modulated laser pulses are generated. Material dispersion and time-dependent modulations of the polarization state can be compensated. These experiments demonstrate the feasibility of adaptive quantum control experiments with polarization-shaped femtosecond laser pulses.
An optimum solar wind coupling function for the AL index
NASA Astrophysics Data System (ADS)
McPherron, Robert L.; Hsu, Tung-Shin; Chu, Xiangning
2015-04-01
We define a coupling function as a product of solar wind factors that partially linearizes the relation between it and a magnetic index. We consider functions that are a product of factors of solar wind speed V, density N, transverse magnetic field B?, and interplanetary magnetic field (IMF) clock angle ?c each raised to a different power. The index is the auroral lower (AL index) which monitors the strength of the westward electrojet. Solar wind data 1995-2014 provide hour averages of the factors needed to calculate optimum exponents. Nonlinear inversion determines both the exponents and linear prediction filters of short data segments. The averages of all exponents are taken as optimum exponents and for V, N, B?, and sin(?c/2) are [1.92, 0.10, 0.79, 3.67] with errors in the second decimal. Hourly values from 1966 to 2014 are used next to calculate the optimum function (opn) and the functions VBs (eys), epsilon (eps), and universal coupling function (ucf). A yearlong window is advanced by 27 days calculating linear prediction filters for the four functions. The functions eps, eys, ucf, and opn, respectively, predict 43.7, 61.2, 65.6, and 68.3% of AL variance. The opn function is 2.74% better than ucf with a confidence interval 2.60-2.86%. Coupling strength defined as the sum of filter weights (nT/mV/m) is virtually identical for all functions and varies systematically with the solar cycle being strongest (188 nT/mV/m) at solar minimum and weakest (104) at solar maximum. Saturation of the polar cap potential approaching solar maximum may explain the variation.
NASA Technical Reports Server (NTRS)
Demaret, J. C.
1975-01-01
The parameters of non-uniform and uniform quantizers up to ten bits of quantization, optimum for a Gaussian input probability and for the magnitude-error distortion criterion are computed. Optimum quantizers must be understood as quantizers with minimum distortion. The numerical method used for the optimization converges relatively rapidly. The comparison between optimum non-uniform quantizers and optimum uniform quantizers is made.
Optimum conditions for high-quality 3D reconstruction in confocal scanning microscopy
NASA Astrophysics Data System (ADS)
Kim, Taehoon; Kim, Taejoong; Lee, SeungWoo; Gweon, Dae-Gab; Seo, Jungwoo
2006-02-01
Confocal Scanning Microscopy (CSM) is very useful to reconstruct 3D image of Bio-cells and the objects that have specification shape in higher axial and lateral resolution and widely used as measurement instrument. A 3D reconstruction is used to visualize confocal images and consists of following processes. The First process is to get 3D data by collecting a series of images at regular focus intervals (Optical Sectioning). The Second process is to fit a curve to a series of 3D data points each pixel. The Third process is to search height information that has maximum value from curve-fitting. However, because of various systematic errors (NOISE) occurred when collecting the information of images through Optical Sectioning and large peak deviation occurred from curve-fitting error, high quality 3D reconstruction is not expected. Also, it takes much time to 3d Reconstruction by using many 3D data in order to acquire high quality and much cost to improve signal-to-noise (SNR) using a higher power laser. So, we are going to define SNR, peak deviation and the order of curve-fitting as important factors and simulate the relation between the factors in order to find a optimum condition for high quality 3D reconstruction in Confoal Scanning Microscopy. If we use optimum condition obtained by this simulation, using a suitable SNR and the suitable number of data and the suitable n-th order curve-fitting, small peak deviation is expected and then, 3D reconstruction of little better quality is expected. Also, it is expected to save.
Modeling and optimum time performance for concurrent processing
NASA Technical Reports Server (NTRS)
Mielke, Roland R.; Stoughton, John W.; Som, Sukhamoy
1988-01-01
The development of a new graph theoretic model for describing the relation between a decomposed algorithm and its execution in a data flow environment is presented. Called ATAMM, the model consists of a set of Petri net marked graphs useful for representing decision-free algorithms having large-grained, computationally complex primitive operations. Performance time measures which determine computing speed and throughput capacity are defined, and the ATAMM model is used to develop lower bounds for these times. A concurrent processing operating strategy for achieving optimum time performance is presented and illustrated by example.
Determination of optimum electrolyte composition for molten carbonate fuel cells
Yuh, C.Y.; Pigeaud, A.
1987-01-01
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 state-of-the-art cell voltage and lifetime.
Optimum value of original events on the PEPT technique
Sadremomtaz, Alireza; Taherparvar, Payvand [University of Guilan, P.O. Box 3489, Rasht, Guilan (Iran, Islamic Republic of)
2011-12-26
Do Positron emission particle tracking (PEPT) has been used to track the motion of a single radioactively labeled tracer particle within a bed of similar particles. In this paper, the effect of the original event fraction on the results precise in two experiments has been reviewed. Results showed that the algorithm can no longer distinguish some corrupt trajectories, in addition to; further iteration reduces the statistical significance of the sample without improving its quality. Results show that the optimum value of trajectories depends on the type of experiment.
Smirnov, Alexander V. [Scientific Research Computing Center, Moscow State University, 119992 Moscow (Russian Federation); Smirnov, Vladimir A. [Skobeltsyn Institute of Nuclear Physics of Moscow State University, 119992 Moscow (Russian Federation); Steinhauser, Matthias [Institut fuer Theoretische Teilchenphysik, Karlsruhe Institute of Technology (KIT), D-76128 Karlsruhe (Germany)
2010-03-19
We compute the three-loop corrections to the potential of two heavy quarks. In particular, we consider in this Letter the purely gluonic contribution which provides, in combination with our previous fermion corrections, the complete answer at three loops.
Fiber lasers with loop reflectors
Urquhart, P. (British Telecom Research Laboratories, Martlesham Heath, Ipswich IP5 7RE, U.K. (GB))
1989-09-01
The theory of homogeneously broadened four level fiber lasers, which use fiber loops as distributed reflective elements, is examined. Such cavities can be made entirely from rare earth doped fiber. The amplifying characteristics of doped fiber loops are examined. The threshold pump power and the loop reflectivity necessary to optimize the lasing output power from an oscillator formed from two loops in series are predicted.
Optimum Aerodynamic Design Using the Navier–Stokes Equations
A. Jameson; L. Martinelli; N. A. Pierce
1998-01-01
: This paper describes the formulation of optimization techniques based on control theory for aerodynamic shape design in viscous\\u000a compressible flow, modeled by the Navier–Stokes equations. It extends previous work on optimization for inviscid flow. The\\u000a theory is applied to a system defined by the partial differential equations of the flow, with the boundary shape acting as\\u000a the control. The
Scanning Polyhedra with DO Loops
Corinne Ancourt; François Irigoin
1991-01-01
Supercompilers perform complex program transformations which often result in new loop bounds. This paper shows that, under the usual assumptions in automatic parallelization, most transformations on loop nests can be expressed as affine transformations on integer sets de ned by polyhedra and that the new loop bounds can be computed with algorithms using Fourier's pairwise elimination method although it is
COLD TEST LOOP INTEGRATED TEST LOOP RESULTS
Abraham, TJ
2003-10-22
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.
Optimum array design to maximize Fisher information for bearing estimation.
Tuladhar, Saurav R; Buck, John R
2011-11-01
Source bearing estimation is a common application of linear sensor arrays. The Cramer-Rao bound (CRB) sets a lower bound on the achievable mean square error (MSE) of any unbiased bearing estimate. In the spatially white noise case, the CRB is minimized by placing half of the sensors at each end of the array. However, many realistic ocean environments have a mixture of both white noise and spatially correlated noise. In shallow water environments, the correlated ambient noise can be modeled as cylindrically isotropic. This research designs a fixed aperture linear array to maximize the bearing Fisher information (FI) under these noise conditions. The FI is the inverse of the CRB, so maximizing the FI minimizes the CRB. The elements of the optimum array are located closer to the array ends than uniform spacing, but are not as extreme as in the white noise case. The optimum array results from a trade off between maximizing the array bearing sensitivity and minimizing output noise power variation over the bearing. Depending on the source bearing, the resulting improvement in MSE performance of the optimized array over a uniform array is equivalent to a gain of 2-5 dB in input signal-to-noise ratio. PMID:22087908
Optimum conditions for inducing laccase production in Lentinus crinitus.
Valle, J S; Vandenberghe, L P S; Santana, T T; Almeida, P H; Pereira, A M; Linde, G A; Colauto, N B; Soccol, C R
2014-01-01
Laccases are environmentally friendly alternatives in many important applications such as in bioremediation, biopulping, textile, and the food industry. They have wide substrate specificity, can oxidize a broad range of compounds, and show potential for use in various industrial processes. Therefore, developing methods to increase laccase production is important. In the current study, we aimed to identify optimum conditions for inducing laccase production in the basidiomycete Lentinus crinitus cultivated under varying nitrogen concentrations and in the presence of potential inducers of laccase production, including copper and phenolic compounds. Peak enzymatic activity (11,977 U/L) occurred at higher nitrogen concentrations (2.8 g/L nitrogen). Regardless of the nitrogen concentration, addition of copper increased the laccase activity and decreased mycelial growth, with maximum laccase activity (14,320 U/L) observed at the highest nitrogen concentration combined with 150 mM CuSO4. In addition, ethanol (0.5 or 1.0 mM) and guaiacol (1.5 mM) increased laccase production to 15,000, 14,800, and 14,850 U/L, respectively. Our findings highlighted the optimum conditions for producing L. crinitusderived laccase as potential alternatives to the conventional production and application of the enzyme. PMID:25366749
High permittivity material selection for design of optimum Hk VDMOS
NASA Astrophysics Data System (ADS)
Naugarhiya, Alok; Kondekar, Pravin N.
2015-07-01
In this paper, we have proposed a novel approach for the selection of high permittivity (Hk) material for the optimum design of Hk vertical double diffused MOS (VDMOS). The optimum design parameters under consideration are geometry, doping concentration and breakdown voltage (BV). We have investigated reliability and sensitivity of the Hk VDMOS using BV and figure-of-merit (FOM) analysis, respectively. Further, we have compared results of Hk VDMOS with superjunction (SJ) VDMOS and conventional VDMOS. The observation clarifies that the higher doping concentration can be used in the drift region of Hk n-pillar when comparing with a SJ VDMOS and conventional VDMOS without affecting the BV. Due to this, the area-specific ON-resistance (Ron A) of the Hk VDMOS is less as compared to the SJ VDMOS and conventional VDMOS with the same BV. Using FOM, we can select the Hk material for maximum doping concentration and maximum BV with lowest Ron A for specific design application of Hk VDMOS.
Characteristics of constrained optimum trajectories with specified range
NASA Technical Reports Server (NTRS)
Erzberger, H.; Lee, H.
1978-01-01
Necessary conditions of optimality are derived for trajectories whose structure is limited to climb, steady cruise, and descent segments. The performance function consists of the sum of fuel and time costs, referred to as direct operating cost (DOC). The state variable is range to go and the independent variable is energy. In this formulation a cruise segment always occurs at the optimum cruise energy for sufficiently large range. At short ranges (500 n. mi. and less) a cruise segment may also occur below the optimum cruise energy. The existence of such a cruise segment depends primarily on the fuel flow vs thrust characteristics and on thrust constraints. If thrust is a free control variable along with airspeed, it is shown that such cruise segments will not generally occur. If thrust is constrained to some maximum value in climb and to some minimum in descent, such cruise segments generally will occur. Computer calculations of typical short-range trajectories obtained about a 1% cost penalty for constraining the thrust.
Optimum flywheel sizing for parallel and series hybrid vehicles
Aceves, S.M.; Smith, J.R.
1996-12-20
Flywheels have the possibility of providing high turnaround efficiency and high specific power output. These characteristics are very important for the successful manufacture of parallel and series hybrid vehicles, which have the potential for providing high fuel economy and very low emissions with range and performance comparable to today`s light-duty vehicles. Flywheels have a high specific power output, but relatively low specific energy output. Therefore, it is of importance to determine energy and power requirements for flywheels applied to light-duty vehicles. Vehicle applications that require an energy storage system with high power and low energy are likely to benefit from a flywheel. In this paper, a vehicle simulation code and a flywheel model are applied to the calculation of optimum flywheel energy storage capacity for a parallel and a series hybrid vehicle. A conventional vehicle is also evaluated as a base-case, to provide an indication of the fuel economy gains that can be obtained with flywheel hybrid vehicles. The results of the analysis indicate that the optimum flywheel energy storage capacity is relatively small. This results in a low weight unit that has a significant power output and high efficiency. Emissions generated by the hybrid vehicles are not calculated, but have the potential of being significantly lower than the emissions from the conventional car.
Investigation of various essential factors for optimum infrared thermography.
Okada, Keiji; Takemura, Kei; Sato, Shigeru
2013-10-01
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
NSDL National Science Digital Library
L. Bryan Ray (AAAS; )
2008-10-17
This article introduces a special issue on the study of biochemical signaling pathways. Complicated biochemical signaling pathways regulate the function of living cells. Such regulatory networks often have â??downstreamâ? components that provide input to components that act earlier in a pathway, creating feedback loops. These feedback loops have the potential to greatly alter the properties of a pathway and how it responds to stimuli. To fully understand these regulatory systems and exploit their vast potential as targets of therapeutic strategies, we need quantitative information on the flow of signals through a pathway and on the timing and location of signaling events within cells. The papers assembled in this special issue and in the companion issue of Science Signaling highlight recent progress in tackling these challenges.
Han, Nanyu; Mu, Yuguang
2013-01-01
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 147–150) 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
NASA Astrophysics Data System (ADS)
Bojowald, Martin
2005-12-01
Quantum gravity is expected to be necessary in order to understand situations where classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e., the fact that the backward evolution of a classical space-time inevitably comes to an end after a finite amount of proper time. This presents a breakdown of the classical picture and requires an extended theory for a meaningful description. Since small length scales and high curvatures are involved, quantum effects must play a role. Not only the singularity itself but also the surrounding space-time is then modified. One particular realization is loop quantum cosmology, an application of loop quantum gravity to homogeneous systems, which removes classical singularities. Its implications can be studied at different levels. Main effects are introduced into effective classical equations which allow to avoid interpretational problems of quantum theory. They give rise to new ki! nds of early universe phenomenology with applications to inflation and cyclic models. To resolve classical singularities and to understand the structure of geometry around them, the quantum description is necessary. Classical evolution is then replaced by a difference equation for a wave function which allows to extend space-time beyond classical singularities. One main question is how these homogeneous scenarios are related to full loop quantum gravity, which can be dealt with at the level of distributional symmetric states. Finally, the new structure of space-time arising in loop quantum gravity and its application to cosmology sheds new light on more general issues such as time.
NASA Astrophysics Data System (ADS)
Bojowald, Martin
2008-07-01
Quantum gravity is expected to be necessary in order to understand situations in which classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e., the fact that the backward evolution of a classical spacetime inevitably comes to an end after a finite amount of proper time. This presents a breakdown of the classical picture and requires an extended theory for a meaningful description. Since small length scales and high curvatures are involved, quantum effects must play a role. Not only the singularity itself but also the surrounding spacetime is then modified. One particular theory is loop quantum cosmology, an application of loop quantum gravity to homogeneous systems, which removes classical singularities. Its implications can be studied at different levels. The main effects are introduced into effective classical equations, which allow one to avoid the interpretational problems of quantum theory. They give rise to new kinds of early-universe phenomenology with applications to inflation and cyclic models. To resolve classical singularities and to understand the structure of geometry around them, the quantum description is necessary. Classical evolution is then replaced by a difference equation for a wave function, which allows an extension of quantum spacetime beyond classical singularities. One main question is how these homogeneous scenarios are related to full loop quantum gravity, which can be dealt with at the level of distributional symmetric states. Finally, the new structure of spacetime arising in loop quantum gravity and its application to cosmology sheds light on more general issues, such as the nature of time.
Cosmic string loop microlensing
NASA Astrophysics Data System (ADS)
Bloomfield, Jolyon K.; Chernoff, David F.
2014-06-01
Cosmic superstring loops within the galaxy microlens background point sources lying close to the observer-string line of sight. For suitable alignments, multiple paths coexist and the (achromatic) flux enhancement is a factor of two. We explore this unique type of lensing by numerically solving for geodesics that extend from source to observer as they pass near an oscillating string. We characterize the duration of the flux doubling and the scale of the image splitting. We probe and confirm the existence of a variety of fundamental effects predicted from previous analyses of the static infinite straight string: the deficit angle, the Kaiser-Stebbins effect, and the scale of the impact parameter required to produce microlensing. Our quantitative results for dynamical loops vary by O(1) factors with respect to estimates based on infinite straight strings for a given impact parameter. A number of new features are identified in the computed microlensing solutions. Our results suggest that optical microlensing can offer a new and potentially powerful methodology for searches for superstring loop relics of the inflationary era.
NASA Astrophysics Data System (ADS)
Grignani, G.; Karczmarek, J. L.; Semenoff, G. W.
2013-12-01
We consider the Polyakov loop operator in finite temperature planar N = 4 supersymmetric Yang-Mills theory defined on a spatial S3 and in representations where the number of boxes in the Young Tableau k is large and scales so that kN remains finite in the large N limit. We review the argument that, in the de-confined phase of the gauge theory, and for symmetric representations with row Young tableau, there is a quantum phase transition in the expectation value of the Polyakov loop operator which occurs as the size of the representation is increased beyond a critical value of kN. We also argue that for completely antisymmetric representations with column tableau, there is no such phase transition. The AdS/CFT dual of such large representation loops are thought to be probe D-branes with k units of fundamental string charge dissolved in their world-volumes. Our results for both symmetric and antisymmetric representations are consistent with what is known about these branes on the thermal AdS black hole background.
Chemical Looping Combustion Kinetics
Edward Eyring; Gabor Konya
2009-03-31
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).
Coupled dual loop absorption heat pump
Sarkisian, Paul H. (Watertown, MA); Reimann, Robert C. (Lafayette, NY); Biermann, Wendell J. (Fayetteville, NY)
1985-01-01
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.
Static shape control for adaptive wings
NASA Astrophysics Data System (ADS)
Austin, Fred; Rossi, Michael J.; van Nostrand, William; Knowles, Gareth; Jameson, Antony
1994-09-01
A theoretical method was developed and experimentally validated, to control the static shape of flexible structures by employing internal translational actuators. A finite element model of the structure, without the actuators present, is employed to obtain the multiple-input, multiple-output control-system gain matrices for actuator-load control as well as actuator-displacement control. The method is applied to the quasistatic problem of maintaining an optimum-wing cross section during various transonic-cruise flight conditions to obtain significant reductions in the shock-induced drag. Only small, potentially achievable, adaptive modifications to the profile are required. The adaptive-wing concept employs actuators as truss elements of active ribs to reshape the wing cross section by deforming the structure. Finite element analyses of an adaptive-rib model verify the controlled-structure theory. Experiments on the model were conducted, and arbitrarily selected deformed shapes were accurately achieved.
NASA Astrophysics Data System (ADS)
Ozbulut, Osman E.; Hurlebaus, Stefan
2010-04-01
Base isolation is an effective method of reducing seismic response of bridges during an earthquake. Rubber isolators are one of the most common types of base isolation systems. As an alternative to conventional rubber isolators such as high damping rubber bearing and lead rubber bearing, smart rubber bearing systems with shape memory alloys (SMAs) have been proposed in recent years. As a class of smart materials, shape memory alloys shows excellent re-centering and considerable damping capabilities which can be exploited to obtain an efficient seismic isolation system. This paper explores effectiveness of shape memory alloy/rubber-based isolation systems for protecting bridges against seismic loads by performing a sensitivity analysis. The isolation system considered in this study consists of a laminated rubber bearing which provides lateral flexibility while supplying high vertical load-carrying capacity and an auxiliary device made of multiple loops SMA wires. The SMA device offers additional energy dissipating and re-centering capability. A threespan continuous bridge is modeled with SMA/rubber-based isolation system. Numerical simulations of the bridge are conducted for various historical ground motions that are spectrally matched to a target design spectrum. The normalized yield strength, yield displacement and pre-stress level of the SMA device and ambient temperature are selected as parameters of the sensitivity study. The variation of seismic response of the bridge with considered parameters is assessed. The optimum values of the normalized yield strength and the yield displacement of the SMA device is found to be in the range of 0.20-0.25 and 40-50 mm, respectively. Also, the SMA/rubber-based isolation system is observed to be more effective when the SMA device is pre-stressed. In addition, it is found that ambient temperature considerably affects the performance of the bridge isolated by SMA/rubber-based isolators.
Simpler Alternative to an Optimum FQPSK-B Viterbi Receiver
NASA Technical Reports Server (NTRS)
Lee, Dennis; Simon, Marvin; Yan, Tsun-Yee
2003-01-01
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.
Optimum detection of an optical image on a photoelectric surface
NASA Technical Reports Server (NTRS)
Helstrom, C. W.; Wang, L.
1972-01-01
The detection of an optical image in the presence of uniform background light is based on a likelihood ratio formed of the numbers of photoelectrons emitted from small elements of a photoelectric surface onto which the image is focused. When diffraction is negligible and the surface has unit quantum efficiency, this detector is equipollent with the optimum detector of the image forming light. Its performance is compared with that of the threshold detector and that of a detector basing its decisions on the total number of photoelectrons from a finite area of the image. The illuminance of the image is postulated to have a Gaussian spatial distribution. All three detectors exhibit nearly the same reliability.
Optimum periodicity of repeated contractile actions applied in mass transport
Ahn, Sungsook; Lee, Sang Joon
2015-01-01
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
Optimum design of a nanoscale spin-Seebeck power device
NASA Astrophysics Data System (ADS)
Liao, Tianjun; Lin, Jian; Su, Guozhen; Lin, Bihong; Chen, Jincan
2015-04-01
A theoretical model of a nanoscale spin-Seebeck power device (SSPD) is proposed based on the longitudinal spin-Seebeck effect in bilayers made of a ferromagnetic insulator and a normal metal. Expressions for the power output and thermal efficiency of the SSPD are derived analytically. The performance characteristics of the nanoscale SSPD are analyzed using numerical simulation. The maximum power output density and efficiency are calculated numerically. The effect of the spin Hall angle on the performance characteristics of the SSPD is analyzed. The choice of materials and the structure of the device are discussed. The optimum criteria of some key parameters of the SSPD, such as the power output density, efficiency, thickness of the normal metal, and the load resistance, are given. The results obtained here could provide a theoretical basis for the optimal design and operation of nanoscale SSPDs.
Optimum source conductance for high frequency superconducting quasiparticle receivers
Ke, Qing; Feldman, M.J. (Univ. of Rochester, NY (United States). Dept. of Electrical Engineering)
1993-04-01
The authors have used the quantum theory of mixing for extensive numerical calculations to determine the mixer source conductance G, required to optimize a superconductor-insulator-superconductor (SIS) quasiparticle heterodyne receiver. The optimum G, matches an empirical formula which can be understood by a simple derivation. Previous work indicated that G, should vary inversely with frequency, and this implies that the critical current density of SIS junctions used for mixing should increase as frequency squared, a stringent constraint on the design of submillimeter SIS mixers. On the contrary, they find that G[sub s] is more weakly dependent upon frequency, and they discuss the implications for the design of submillimeter SIS mixers.
Optimum Integrated Heterodyne Photoreceiver for Coherent Lidar Applications
NASA Technical Reports Server (NTRS)
Amzajerdian, Farzin; Pierrottet, Diego; Singh, Upendra; Kavaya, Michael
2005-01-01
Many coherent lidar applications, particularly airborne and space-based applications, impose stringent power and size constraints while requiring high levels of sensitivity. For this reason, optimization of the lidar heterodyne photoreceiver is one of the critical steps in ensuring full utilization of limited resources to achieve the required sensitivity. The analysis of 2-micron heterodyne receivers shows that substantial improvement of the order of 3 dB can be obtained by proper optimization of the receiver key control parameters and elimination of its parasitic capacitances by integrating the detector, its bias circuit, and the preamplifier on a single substrate. This paper describes analytical steps for defining optimum heterodyne receiver design parameters and development of experimental devices operating at 2-micron wavelength.
Optimum detection of tones transmitted by a spacecraft
NASA Technical Reports Server (NTRS)
Simon, M. K.; Shihabi, M. M.; Moon, T.
1995-01-01
The performance of a scheme proposed for automated routine monitoring of deep-space missions is presented. The scheme uses four different tones (sinusoids) transmitted from the spacecraft (S/C) to a ground station with the positive identification of each of them used to indicate different states of the S/C. Performance is measured in terms of detection probability versus false alarm probability with detection signal-to-noise ratio as a parameter. The cases where the phase of the received tone is unknown and where both the phase and frequency of the received tone are unknown are treated separately. The decision rules proposed for detecting the tones are formulated from average-likelihood ratio and maximum-likelihood ratio tests, the former resulting in optimum receiver structures.
A digital phase-locked loop with a fast acquisition time and low phase jitter
B. K. Altay; R. Bozkurt
1989-01-01
A first-order digital phase locked loop (DPLL) is presented. The phase error is accumulated and averaged over a number of cycles of the DPLL output, which in turn determines the number of pulses inserted\\/deleted from a high-frequency clock. The optimum number of cycles of the DPLL output used for averaging are determined for the acquisition and steady-state modes. For fast
Shapes and Shaping of Planetary Nebulae
Bruce Balick; Adam Frank
2002-01-01
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
The optimum choice of gate width for neutron coincidence counting
NASA Astrophysics Data System (ADS)
Croft, S.; Henzlova, D.; Favalli, A.; Hauck, D. K.; Santi, P. A.
2014-11-01
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.
Energy levels and far-infrared spectra of oval-shaped nanorings
Gutiérrez, W.; García, L. F.; Mikhailov, I. D. [Escuela de Física, Universidad Industrial de Santander, A. A. 678, Bucaramanga (Colombia)
2014-05-15
The evolution of the Aharonov-Bohm oscillation of low-lying states and far infrared spectrum associated to variation of the path curvature for electron motion along nanorings with centerlines in a form of a set of Cassini ovals, whose shape is changed continuously from a single elongated loop to two separated loops is theoretically investigated.
Optimum Structural and Manufacturing Design of a Braided Hollow Composite Part
NASA Astrophysics Data System (ADS)
Ghiasi, Hossein; Lessard, Larry; Pasini, Damiano; Thouin, Maxime
2010-04-01
Simultaneous material consolidation and shaping, as performed in manufacturing of composite materials, causes a strong interconnection between structural and manufacturing parameters which makes the design process complicated. In this paper, the design of a carbon fiber bicycle stem is examined through the application of a multi-objective optimization method to illustrate the interconnection between structural and manufacturing objectives. To demonstrate the proposed method, a test case dealing with the design of composite part with complex geometry, small size and hollow structure is described. Bladder-assisted Resin Transfer Molding is chosen as the manufacturing method. A finite element model of the stem is created to evaluate the objectives of the structural design, while a simplified 2D model is used to simulate the flow inside the preform during the injection process. Both models are formulated to take into account the variation of fiber orientation, thickness and fiber volume fraction as a function of braid diameters, injection pressure and bladder pressure. Finally, a multiobjective optimization method, called Normalized Normal Constraint Method, is used to find a set of solutions that simultaneously optimizes weight, filling time and strength. The solution to the problem is a set of optimum designs which represent the Pareto frontier of the problem. Pareto frontier helps to gain insight into the trade-off among objectives, whose presence and importance is confirmed by the numerical results presented in this paper.
OPTIMUM ACTUATOR SELECTION WITH A GENETIC ALGORITHM FOR AIRCRAFT CONTROL
Coello, Carlos A. Coello
of aerodynamically morphing the shape of the wing as needed. The cost and complexity of such a vehicle is obviously Langley Research Center ABSTRACT: The placement of actuators on a wing determines the control without at the same time causing much pitch or yaw. For a typical wing, there is a large set of candidate
Two loop divergences studied with one loop constrained differential renormalization
Seijas, Cesar [Departamento de Fi sica de Parti culas, Universidade de Santiago de Compostela, E-15706 Santiago de Compostela (Spain)]. E-mail: cesar@fpaxp1.usc.es
2007-08-15
In the context of differential renormalization, using constrained differential renormalization rules at one-loop, we show how to obtain concrete results in two-loop calculations without making use of Ward identities. In order to do that, we obtain a list of integrals with overlapping divergences compatible with CDR that can be applied to various two-loop background field calculations. As an example, we obtain the two-loop coefficient of the beta function of QED, SuperQED and Yang-Mills theory.
NSDL National Science Digital Library
Pam Stryker
2010-01-01
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.
Optical parametric loop mirror
NASA Astrophysics Data System (ADS)
Mori, K.; Morioka, T.; Saruwatari, M.
1995-06-01
A novel configuration for four-wave mixing (FWM) is proposed that offers the remarkable feature of inherently separating the FWM wave from the input pump and signal waves and suppressing their background amplified stimulated emission without optical filtering. In the proposed configuration, an optical parametric loop mirror, two counterpropagating FWM waves generated in a Sagnac interferometer interfere with a relative phase difference that is introduced deliberately. FWM frequency-conversion experiments in a polarization-maintaining fiber achieved more than 35 dB of input-wave suppression against the FWM wave.
Dassau, E; Atlas, E; Phillip, M
2011-02-01
Closed-loop algorithms can be found in every aspect of everyday modern life. Automation and control are used constantly to provide safety and to improve quality of life. Closed-loop systems and algorithms can be found in home appliances, automobiles, aviation and more. Can one imagine nowadays driving a car without ABS, cruise control or even anti-sliding control? Similar principles of automation and control can be used in the management of diabetes mellitus (DM). The idea of an algorithmic/technological way to control glycaemia is not new and has been researched for more than four decades. However, recent improvements in both glucose-sensing technology and insulin delivery together with advanced control and systems engineering made this dream of an artificial pancreas possible. The artificial pancreas may be the next big step in the treatment of DM since the use of insulin analogues. An artificial pancreas can be described as internal or external devices that use continuous glucose measurements to automatically manage exogenous insulin delivery with or without other hormones in an attempt to restore glucose regulation in individuals with DM using a control algorithm. This device as described can be internal or external; can use different types of control algorithms with bi-hormonal or uni-hormonal design; and can utilise different ways to administer them. The different designs and implementations have transitioned recently from in silico simulations to clinical evaluation stage with practical applications in mind. This may mark the beginning of a new era in diabetes management with the introduction of semi-closed-loop systems that can prevent or minimise nocturnal hypoglycaemia, to hybrid systems that will manage blood glucose (BG) levels with minimal user intervention to finally fully automated systems that will take the user out of the loop. More and more clinical trials will be needed for the artificial pancreas to become a reality but initial encouraging results are proof that we are on the right track. We attempted to select recent publications that will present these current achievements in the quest for the artificial pancreas and that will inspire others to continue to progress this field of research. PMID:21323809
The double loop mattress suture
Biddlestone, John; Samuel, Madan; Creagh, Terry; Ahmad, Tariq
2014-01-01
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
Unplugging of Prolene IOL Loops
Fridbert Jonasson; John M. S. McConnell
1987-01-01
From end 1981 until early 1984, 415 Severin-type lenses were implanted in our two centres. In 10 instances i.e. 2.4%, we experienced unplugging of the anterior 12 o’clock positioned loop, apparently a result of the loop being held with the insertions forceps during insertion. The unplugging of the loop possibly affected the visual outcome in one instance.
Shape Optimization of Rubber Bushing Using Differential Evolution Algorithm
2014-01-01
The objective of this study is to design rubber bushing at desired level of stiffness characteristics in order to achieve the ride quality of the vehicle. A differential evolution algorithm based approach is developed to optimize the rubber bushing through integrating a finite element code running in batch mode to compute the objective function values for each generation. Two case studies were given to illustrate the application of proposed approach. Optimum shape parameters of 2D bushing model were determined by shape optimization using differential evolution algorithm. PMID:25276848
Adaptive optimisation of a generalised phase contrast beam shaping system
Kenny, F.; Choi, F.S.; Glückstad, J.; Booth, M.J.
2015-01-01
The generalised phase contrast (GPC) method provides versatile and efficient light shaping for a range of applications. We have implemented a generalised phase contrast system that used two passes on a single spatial light modulator (SLM). Both the pupil phase distribution and the phase contrast filter were generated by the SLM. This provided extra flexibility and control over the parameters of the system including the phase step magnitude, shape, radius and position of the filter. A feedback method for the on-line optimisation of these properties was also developed. Using feedback from images of the generated light field, it was possible to dynamically adjust the phase filter parameters to provide optimum contrast.
Accelerating the loop expansion
Ingermanson, R.
1986-07-29
This thesis introduces a new non-perturbative technique into quantum field theory. To illustrate the method, I analyze the much-studied phi/sup 4/ theory in two dimensions. As a prelude, I first show that the Hartree approximation is easy to obtain from the calculation of the one-loop effective potential by a simple modification of the propagator that does not affect the perturbative renormalization procedure. A further modification then susggests itself, which has the same nice property, and which automatically yields a convex effective potential. I then show that both of these modifications extend naturally to higher orders in the derivative expansion of the effective action and to higher orders in the loop-expansion. The net effect is to re-sum the perturbation series for the effective action as a systematic ''accelerated'' non-perturbative expansion. Each term in the accelerated expansion corresponds to an infinite number of terms in the original series. Each term can be computed explicitly, albeit numerically. Many numerical graphs of the various approximations to the first two terms in the derivative expansion are given. I discuss the reliability of the results and the problem of spontaneous symmetry-breaking, as well as some potential applications to more interesting field theories. 40 refs.
NASA Astrophysics Data System (ADS)
Coutsias, Evangelos A.; Seok, Chaok; Wester, Michael J.; Dill, Ken A.
The problem of tripeptide loop closure is formulated in terms of the angles {?i} 3i=1 describing the orientation of each peptide unit about the virtual axis joining the C? atoms. Imposing the constraint that at the junction of two such units the bond angle between the bonds C??N and C??C is fixed at some prescribed value ? results in a system of three bivariate polynomials in ui ? tan ?i/2 of degree 2 in each variable. The system is analyzed for the existence of common solutions by making use of resultants, determinants of matrices composed of the coefficients of two (or more) polynomials, whose vanishing is a necessary and sufficient condition for the polynomials to have a common root. Two resultants are compared: the classical Sylvester resultant and the Dixon resultant. It is shown that when two of the variables are eliminated in favor of the third, a polynomial of degree 16 results. To each one of its real roots, there is a corresponding common zero of the system. To each such zero, there corresponds a consistent conformation of the chain. The Sylvester method can find these zeros among the eigenvalues of a 24 × 24 matrix. For the Dixon approach, after removing extraneous factors, an optimally sized eigenvalue problem of size 16 × 16 results. Finally, the easy extension to the more general problem of triaxial loop closure is presented and an algorithm for implementing the method on arbitrary chains is given.
A study on the optimum fast neutron flux for boron neutron capture therapy of deep-seated tumors.
Rasouli, Fatemeh S; Masoudi, S Farhad
2015-02-01
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
Changes in lung tumor shape during respiration
NASA Astrophysics Data System (ADS)
Kyriakou, E.; McKenzie, D. R.
2012-02-01
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.
Loop-the-Loop: An Easy Experiment, A Challenging Explanation
B. Asavapibhop; N. Suwonjandee
2010-01-01
A loop-the-loop built by the Institute for the Promotion of Teaching Science and Technology (IPST) was used in Thai high school teachers training program to demonstrate a circular motion and investigate the concept of the conservation of mechanical energy. We took videos using high speed camera to record the motions of a spherical steel ball moving down the aluminum inclined
Optimum material design of minimum structural compliance under seepage constraint
Shengli Xu; Gengdong Cheng
2010-01-01
In filtration and chemical engineering industry the load carrying capacity and seepage performances are very important for\\u000a a successful filter design. We study a two-scale structural design optimization problem to minimize structural compliance\\u000a under given seepage flow rate and material porosity constraints. Structural size, shape and topology are given because of\\u000a other functional requirements. Structural material used is macro homogeneous
Optimum design of a gearbox for low vibration
NASA Technical Reports Server (NTRS)
Inoue, Katsumi; Townsend, Dennis P.; Coy, John J.
1992-01-01
A computer program was developed for designing a low vibration gearbox. The code is based on a finite element shell analysis, a modal analysis, and a structural optimization method. In the finite element analysis, a triangular shell element with 18 degrees-of-freedom is used. In the optimization method, the overall vibration energy of the gearbox is used as the objective function and is minimized at the exciting frequency by varying the finite element thickness. Modal analysis is used to derive the sensitivity of the vibration energy with respect to the design variable. The sensitivity is representative of both eigenvalues and eigenvectors. The optimum value is computed by the gradient projection method and a unidimensional search procedure under the constraint condition of constant weight. The computer code is applied to a design problem derived from an experimental gearbox in use at the NASA Lewis Research Center. The top plate and two side plates of the gearbox are redesigned and the contribution of each surface to the total vibration is determined. Results show that optimization of the top plate alone is effective in reducing total gearbox vibration.
OPTIMUM INTEGRAL DESIGN FOR MAXIMIZING THE FIELD IN SHORT MAGNETS.
GUPTA,R.
2004-10-03
An Optimum Integral Design is introduced for cosine(n{theta}) coils where the entire end-to-end length of the coil generates field with the dilution from ends practically eliminated. The benefits of such a design are particularly significant in short magnets where the overall coil length is comparable to or a few times the coil diameter. The integral field strength is further enhanced since the design allows a larger number of turns than in typical magnet coils. In this concept, the ends and body harmonics are optimized together to create an integral cosine(n{theta}) azimuthal current distribution. The concept was initially developed for wire/cable wound magnets where the bend radius of turns in the ends can be small. However, the benefit of this general approach can be applied to cable magnets as well. The magnetic design of a corrector dipole for the AGS helical magnet, which was recently built and tested, is presented as one of several examples. The other examples include a few sub-compact designs: a dipole with coil length less than a coil diameter, a quadrupole with coil length less than a coil radius, etc. Apart from generating a large integral field for the given length, the computed integral field harmonics in these designs are only a few parts in 10,000 at 2/3, of the coil radius.
Optimum and efficient sampling for variational quantum Monte Carlo.
Trail, J R; Maezono, Ryo
2010-11-01
Quantum mechanics for many-body systems may be reduced to the evaluation of integrals in 3N dimensions using Monte Carlo, providing the Quantum Monte Carlo ab initio methods. Here we limit ourselves to expectation values for trial wave functions, that is to variational quantum Monte Carlo. Almost all previous implementations employ samples distributed as the physical probability density of the trial wave function, and assume the central limit theorem to be valid. In this paper we provide an analysis of random error in estimation and optimization that leads naturally to new sampling strategies with improved computational and statistical properties. A rigorous lower limit to the random error is derived, and an efficient sampling strategy presented that significantly increases computational efficiency. In addition the infinite variance heavy tailed random errors of optimum parameters in conventional methods are replaced with a Normal random error, strengthening the theoretical basis of optimization. The method is applied to a number of first row systems and compared with previously published results. PMID:21054019
Optimum Conditions for Artificial Fruiting Body Formation of Cordyceps cardinalis
Kim, Soo-Young; Shrestha, Bhushan; Sung, Gi-Ho; Han, Sang-Kuk
2010-01-01
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
Optimum frequency for subsurface-imaging synthetic-aperture radar
Brock, B.C.; Patitz, W.E.
1993-05-01
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.
NSDL National Science Digital Library
2011-01-01
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.
Assessing catchment connectivity using hysteretic loops
NASA Astrophysics Data System (ADS)
Keesstra, Saskia; Masselink, Rens; Goni, Mikel; Campo, Miguel Angel; Gimenez, Rafael; Casali, Javier; Seeger, Manuel
2015-04-01
Sediment connectivity is a concept which can explain the origin, pathways and sinks of sediments within landscapes. This information is valuable for land managers to be able to take appropriate action at the correct place. Hysteresis between sediment and water discharge can give important information about the sources , pathways and conditions of sediment that arrives at the outlet of a catchment. "Hysteresis" happens when the sediment concentration associated with a certain flow rate is different depending on the direction in which the analysis is performed -towards the increase or towards the diminution of the flow. This phenomenon to some extent reflects the way in which the runoff generation processes are conjugated with those of the production and transport of sediments, hence the usefulness of hysteresis as a diagnostic hydrological parameter. However, the complexity of the phenomena and factors which determine hysteresis make its interpretation uncertain or, at the very least, problematic. Many types of hysteretic loops have been described as well as the cause for the shape of the loop, mainly describing the origin of the sediments. In this study, several measures to objectively classify hysteretic loops in an automated way were developed. These were consecutively used to classify several hundreds of loops from several agricultural catchments in Northern Spain. The data set for this study comes from four experimental watersheds in Navarre (Spain), owned and maintained by the Government of Navarre. These experimental watersheds have been monitored and studied since 1996 (La Tejería and Latxaga) and 2001 (Oskotz "principal", Op, and Oskotz "woodland", Ow). La Tejería and Latxaga watersheds, located in the Central Western part of Navarre, are roughly similar to each other regarding size (approximately 200 ha), geology (marls and sandstones), soils (fine texture topsoil), climate (humid sub Mediterranean) and land use (80-90% cultivated with winter grain crops). On the other hand, Op (ca.1,700 ha) is covered with forest and pasture (cattle-breeding); while Ow (ca. 500 ha), a sub-watershed of the Op, is almost completely covered with forest. The predominant climate in Op/Ow is sub-Atlantic. Furthermore, antecedent conditions and event characteristics were analysed. The loops were compared quantitatively and qualitatively between catchments for similar events and within the catchments for events with different characteristics.
Patrick T. Mather; Xiaofan Luo; Ingrid A. Rousseau
2009-01-01
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
ERIC Educational Resources Information Center
Markson, Lori; Diesendruck, Gil; Bloom, Paul
2008-01-01
When children learn the name of a novel object, they tend to extend that name to other objects similar in shape--a phenomenon referred to as the shape bias. Does the shape bias stem from learned associations between names and categories of objects, or does it derive from more general properties of children's understanding of language and the…
NASA Technical Reports Server (NTRS)
Weislogel, Mark M. (Inventor)
2002-01-01
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.
Chesi, Stefano [Department of Physics, McGill University, Montreal, Quebec H3A 2T8 (Canada) [Department of Physics, McGill University, Montreal, Quebec H3A 2T8 (Canada); CEMS, RIKEN, Wako, Saitama 351-0198 (Japan); Jaffe, Arthur [Harvard University, Cambridge, Massachusetts 02138 (United States) [Harvard University, Cambridge, Massachusetts 02138 (United States); Department of Physics, University of Basel, Basel (Switzerland); Institute for Theoretical Physics, ETH Zürich, Zürich (Switzerland); Loss, Daniel [CEMS, RIKEN, Wako, Saitama 351-0198 (Japan) [CEMS, RIKEN, Wako, Saitama 351-0198 (Japan); Department of Physics, University of Basel, Basel (Switzerland); Pedrocchi, Fabio L. [Department of Physics, University of Basel, Basel (Switzerland)] [Department of Physics, University of Basel, Basel (Switzerland)
2013-11-15
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.
Pei, L.; Klebaner, A.; Theilacker, J.; Soyars, W.; Martinez, A.; Bossert, R.; DeGraff, B.; Darve, C.; /Fermilab
2011-06-01
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.
Thermodynamics in Loop Quantum Cosmology
Li-Fang Li; Jian-Yang Zhu
2009-01-01
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
Light-Cone Wilson Loops and the String\\/Gauge Correspondence
Yuri Makeenko
2003-01-01
We investigate a Pi-shape Wilson loop in N=4 super Yang-Mills theory, which lies partially at the light-cone, and consider an associated open superstring in AdS5 × S5. We discuss how this Wilson loop determines the anomalous dimensions of conformal operators with large Lorentz spin and present an explicit calculation in perturbation theory to order lambda. We find the minimal surface
Shang, Jer-Yu (Fairfax, VA); Mei, Joseph S. (Morgantown, WV); Slagle, Frank D. (Kingwood, WV); Notestein, John E. (Morgantown, WV)
1984-01-01
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.
Early structure formation from cosmic string loops
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
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.
Coronal loops above an active region: Observation versus model
NASA Astrophysics Data System (ADS)
Bourdin, Philippe-A.; Bingert, Sven; Peter, Hardi
2014-12-01
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.
VLA observations of postflare loops at 20 centimeter wavelength
NASA Technical Reports Server (NTRS)
Velusamy, T.; Kundu, M. R.
1981-01-01
From observations with the VLA on May 19, 1979, the first spatially resolved observations of 20 cm radio emission originating from postflare loop systems are presented. The 20 cm burst was associated with an H alpha flare and a soft X-ray burst, and most of the intense radio emission occurred at the end of the H alpha flare and in the decay phase of the X-ray burst. The 20 cm 'snapshot' maps of the burst source obtained with a resolution of 12 arcsec x 24 arcsec show that the radio emission occurred in structures that are similar in size and shape to the systems of loops observed in X-rays. This postflare radio emission is considered to be similar to the H alpha and X-ray emissions originating in postflare loops. The radio observations of postflare loops have the unique advantage that they offer an important means of determining the average magnetic field strength in these loops. Interpreting the radio emission in this particular event as thermal gyroradiation or as nonthermal synchrotron radiation, the magnetic field strength is estimated to lie in the range of approximately 120-170 gauss.
VLA observations of postflare loops at 20 centimeter wavelength
Velusamy, T.; Kundu, M.R.
1981-01-15
From observations with the VLA on 1979 May 19, we present the first spatially resolved observations of 20 cm radio emission originating from postflare loop systems. The 20 cm burst was associated with an Ha flare and a soft X-ray burst, and most of the intense radio emission occurred at the end of the Ha flare and in the decay phase of the X-ray burst. The 20 cm ''snapshot'' maps of the burst source obtained with a resolution of 12''--24'' show that the radio emission occurred in structures that are similar in size and shape to the systems of loops observed in X-rays. We consider that this postflare radio emission is similar to the Ha and X-ray emissions originating in postflare loops. The radio observations of postflare loops have the unique advantage that they offer an important means of determining the average magnetic field strength in these loops. Interpreting the radio emission in this particular event as thermal gyroradiation or as nonthermal synchrotron radiation, we estimate that the magnetic field strength lies in the range approx.120--170 gauss.
Optimum Thickness of MnBi Films for Magnetooptical Memory.
Esho, S; Noguchi, S; Ono, Y; Nagao, M
1974-04-01
Magnetic behavior of thermomagnetically written domains in MnBi films (400 A to 1200 A thick) has been studied. The written domains were circular in shape but became deformed and irregular with increasing film thickness. The circular domains of 1.5 microm in diameter were stable only in the films thinner than 700 A for writing and erasing processes. The stability of written domains can be explained by introducing measured wall coercivity values into a domain theory. The film wall coercivity was varied from 250 Oe to 800 Oe in inverse proportion to the film thickness. PMID:20126080
Optimum dose of radiotherapy for chemodectomas of the middle ear
Kim, J.A.; Elkon, D.; Lim, M.L.; Constable, W.C.
1980-07-01
Forty patients with chemodectomas of the middle ear were seen at the University of Virginia Hospital from 1932 to 1978. Surgery, post-operative radiotherapy or radiotherapy alone were the treatment modalities employed depending on the extent of the disease. These have been reviewed with regard to the clinical presentation and results of treatment with long term follow-up of 1 to 30 years. An attempt was made to determine the optimum dose of radiotherapy based on our data and reported cases in the literature. The majority of patients complaining of tinnitus, otalgia and pulsation obtained significant if not complete relief of symptoms. Cranial nerve defects, however, ofter persisted after therapy. Tumor was considered to be controlled if there was no increase in its size or progression of symptoms. Tumor control was obtained in eight of 10 early patients but only in two of seven more patients with advanced disease with total resection. Control rate with post-operative radiotherapy after subtotal resection was 85%. Radiotherapy alone was used for inoperable or recurrent tumors and control was obtained in 88% of them. In addition to our data, the radiation dose used in over 200 patients reported in the literature was analyzed. There was only a 2% recurrence rate in patients who received 4000 rad/4 weeks or higher. Twenty-two percent of patients treated with less than 4000 rad developed recurrence. The tendency is to use a lower dose of postoperative treatment and a higher dose for gross inoperable tumors. 4000 rad/4 weeks seems to be adequate for control of postoperative residual disease and no more than 5000 rad/5 weeks are required even for advanced inoperable cases. By keeping the dose below 5000 rad/5 weeks, the incidence of complications such as brain necrosis is greatly decreased.
Optimum Anthropometric Criteria for Ideal Body Composition Related Fitness
Kilani, Hashem; Abu-Eisheh, Asem
2010-01-01
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 166–190 cm and aged 20–42 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 5.6–6.7 %. 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
NASA Astrophysics Data System (ADS)
Sheiko, Sergei; Zhou, Jing; White, Sarah; Ashby, Valerie
2012-02-01
An ``Achilles' heel'' of shape memory materials is that shape transformations triggered by an external stimulus are usually irreversible. Here we present a new concept of reversible transitions between two well-defined shapes by controlling hierarchic crystallization of a dual-network elastomer. The reversibility was demonstrated for different types of shape transformations including rod bending, winding of a helical coil, and widening an aperture. The distinct feature of the reversible shape alterations is that both counter-shapes are infinitely stable at a temperature of exploitation. Shape reversibility is highly desirable property in many practical applications such as non-surgical removal of a previously inserted catheter and handfree wrapping up of an earlier unraveled solar sail on a space shuttle.
Rotation Angle for the Optimum Tracking of One-Axis Trackers
Marion, W. F.; Dobos, A. P.
2013-07-01
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.
B. T. F. CHUNG; J. R. IYER
1993-01-01
An integral approach is extended to determine the optimum dimensions for rectangular longitudinal fins and cylindrical pin fins by incorporating transverse heat conduction. The effects of variable heat transfer coefficient and heat transfer from the fin tip are also taken into account. The mathematical expression for optimum dimension ration thus obtained is found to be as simple as that of
Simplified optimum sizing and cost analysis for compact heat exchanger in VHTR
E. S. Kim; C. H. Oh; S. Sherman
2008-01-01
In this study, the optimum size of the compact heat exchanger has been developed based on its weight and pumping power for the reference design of 600MWt very high temperature gas-cooled reactor (VHTR) system. Alloy 617 was selected as a construction material. The optimum size and a number of configurations for the reference design of the VHTR with an intermediate
A Specific Genetic Algorithm for Optimum Path Planning in Intelligent Transportation System
Qing Li; Guangjun Liu; Wei Zhang; Cailu Zhao; Yixin Yin; Zhiliang Wang
2006-01-01
A specific genetic algorithm is proposed in this paper for optimum path planning. Operations such as encoding, crossover and mutation are tailored to fit optimum path planning. Simulation results show that the specific genetic algorithm has advantages such as rapid calculation speed and high probability of optimal solution. It is a new approach for solving shortest path problems in practical
Katsuya Ishikawa; Ikuo Nakamura
1989-01-01
To obtain the best performance and optimum geometries for a wide range of diffuser geometries, experiments have been performed on many conical diffusers having uniform inlet flow outside the thin inlet boundary layer and free discharge using air flow. Performance data for diffusers are represented comprehensively in a pressure recovery coefficient and effectiveness chart including optimum geometry lines. A comparison
Y. Q. Zhao
2003-01-01
This paper aims to examine the correlations between floc physical properties, such as size, density, structure (in terms of fractal dimension) and optimum dosage in an alum sludge conditioning with organic polymer and also dewatering using an air pressure plate apparatus. Initially, optimum dosage was evaluated by a modified specific resistance to filtration (SRF). Thereafter, floc size, density and structure
Optimum Fuel Loads in Migratory Birds: Distinguishing Between Time and Energy Minimization
Anders Hedenström; Thomas Alerstam
1997-01-01
By combining the potential flight range of fuel with different migration policies, the optimum departure fuel load for migratory birds can be calculated. We evaluate the optimum departure fuel loads associated with minimization of three different currencies: (1) overall time of migration, (2) energy cost of transport and (3) total energy coast of migration. Predicted departure loads are highest for
Charles F. Babbs; Karl B. Kern
2002-01-01
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:
OPTIMUM SEED PLANTING SIZE AND MESH SIZE OF BOTTOMLESS MESH ENCLOSURES FOR CULTURING THE NORTHERN
Florida, University of
OPTIMUM SEED PLANTING SIZE AND MESH SIZE OF BOTTOMLESS MESH ENCLOSURES FOR CULTURING THE NORTHERN The University of Georgia, Athens, Georgia Marine Extension Bulletin No. 25, July 2002 QUAHOG #12;i Optimum seed, Mercenaria mercenaria, seed of different sizes planted under various mesh sizes of bottomless-mesh enclosures
C. van der Tol; A. G. C. A. Meesters; A. J. Dolman; M. J. Waterloo
2008-01-01
This paper presents a model to predict optimum vegetation characteristics in water stressed conditions. Starting point is the principle of homeostasis of water flow through the soil-vegetation-atmosphere continuum. Combining this with a biochemical model for photosynthesis, a relationship between photosynthetic capacity, stomatal regulation, and hydraulic properties of the vegetation is derived. Optimum photosynthetic capacity and internal carbon dioxide concentration are
A novel optimum operating point tracker of the solar cell power supply system
K. Kobayashi; Hirofumi Matsuo; Yutaka Sekine
2004-01-01
When the solar array is used as an input power source, the optimum operating point tracker is often employed to exploit more effectively the solar array as an electric power source and to obtain the maximum electric power at all times even when the light intensity and environmental temperature of the solar array are varied. Usually, the optimum operating point
Optimum shell separation for closed axial cylindrical magnetic shields Eugene Papernoa
Paperno, Eugene
Optimum shell separation for closed axial cylindrical magnetic shields Eugene Papernoa Department 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
Voltage Stability Analysis With Optimum Size and Location Based Synchronous Machine DG
Pota, Himanshu Roy
Voltage Stability Analysis With Optimum Size and Location Based Synchronous Machine DG Adnan Anwar feeder has been considered to determine the optimum size and location of a synchronous machine based DG.pota@adfa.edu.au. At present, most distributed generation installations employ induction and synchronous machines [7]. Before
An optimum channel-routing algorithm for polycell layouts of integrated circuits
B. W. Kernighan; D. G. Schweikert; G. Persky
1973-01-01
This paper presents an algorithm for finding optimum routings for interconnection paths in a channel between two parallel rows of circuit cells. The algorithm, although based on branch and bound, has provided optimum routings for circuits with 50 to 60 nets in a minute or two of computing.
Optimum control of N-input K-output matrix converters
P. Tenti; L. Malesani; L. Rossetto
1992-01-01
Significant developments of the general optimum control theory presented in a previous paper by the authors (1988) are discussed for the specific case of multiphase matrix converters. Results hold, regardless of system configuration, input and output voltage waveforms, and loads. Applications to the most practical converter structures are illustrated, and implementation criteria of the optimum control method are derived. Simulated
Abdelmalek BOUHADJERA
An ultrasonic apparatus based on a mode conversion technique is described. It involves the measurement of the velocity of both compressional and shear waves in prism shaped specimens with only one transducer. The shear waves are generated through mode conversion at the interface between water and the specimen under test. The optimum coupling of the transducer and the special arrangement
The Coupling of Shape Dynamics to Matter
Henrique Gomes
2011-12-02
Shape Dynamics (SD) is a theory dynamically equivalent to vacuum General Relativity (GR), which has a different set of symmetries. It trades refoliation invariance, present in GR, for local 3-dimensional conformal invariance. This contribution to the Loops 11 conference addresses one of the more urgent questions regarding the equivalence: is it possible to incorporate normal matter in the new framework? The answer is yes, in certain regimes. We present general criteria for coupling and apply it to a few examples.The outcome presents bounds and conditions on scalar densities (such as the Higgs potential and the cosmological constant) not present in GR.
NASA Technical Reports Server (NTRS)
Aung, M.
1992-01-01
Computer simulated noise performance of the symbol synchronizer loop (SSL) in the Block 5 receiver is compared with the theoretical noise performance. Good agreement is seen at the higher loop SNR's (SNR(sub L)'s), with gradual degradation as the SNR(sub L) is decreased. For the different cases simulated, cycle slipping is observed (within the simulation time of 10(exp 4) seconds) at SNR(sub L)'s below different thresholds, ranging from 6 to 8.5 dB, comparable to that of a classical phase-locked loop. An important point, however, is that to achieve the desired loop SNR above the seemingly low threshold to avoid cycle slipping, a large data-to-loop-noise power ratio, P(sub D)/(N(sub 0)B(sub L)), is necessary (at least 13 dB larger than the desired SNR(sub L) in the optimum case and larger otherwise). This is due to the large squaring loss (greater than or equal to 13 dB) inherent in the SSL. For the special case of symbol rates approximately equaling the loop update rate, a more accurate equivalent model accounting for an extra loop update period delay (characteristic of the SSL phase detector design) is derived. This model results in a more accurate estimation of the noise-equivalent bandwidth of the loop.
McCormack, B.; Kaita, R.; Kugel, H.; Hatcher, R.
2000-01-06
The Rogowski Loop is one of the most basic diagnostics for tokamak operations. On the National Spherical Torus Experiment (NSTX), the plasma current Rogowski Loop had the constraints of the very limited space available on the center stack, 5,000 volt isolation, flexibility requirements as it remained a part of the Center Stack assembly after the first phase of operation, and a +120 C temperature requirement. For the second phase of operation, four Halo Current Rogowski Loops under the Center Stack tiles will be installed having +600 C and limited space requirements. Also as part of the second operational phase, up to ten Rogowski Loops will installed to measure eddy currents in the Passive Plate support structures with +350 C, restricted space, and flexibility requirements. This presentation will provide the details of the material selection, fabrication techniques, testing, and installation results of the Rogowski Loops that were fabricated for the high temperature operational and bakeout requirements, high voltage isolation requirements, and the space and flexibility requirements imposed upon the Rogowski Loops. In the future operational phases of NSTX, additional Rogowski Loops could be anticipated that will measure toroidal plasma currents in the vacuum vessel and in the Passive Plate assemblies.
Picophytoplankton physiology and the microbial loop
NASA Astrophysics Data System (ADS)
Stawiarski, Beate
2013-04-01
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.
Aridification in continental Asia after the Middle Eocene Climatic Optimum (MECO)
NASA Astrophysics Data System (ADS)
Bosboom, Roderic E.; Abels, Hemmo A.; Hoorn, Carina; van den Berg, Bas C. J.; Guo, ZhaoJie; Dupont-Nivet, Guillaume
2014-03-01
Global climate cooling from greenhouse to icehouse conditions occurred across an enigmatic transitional interval during the Eocene epoch characterized by incipient polar ice-sheet formation as well as short-lived warming events, of which the Middle Eocene Climatic Optimum (MECO) is most noticeable. Understanding this critical period requires high-resolution records that are being gathered in marine basins, but are still lacking in the terrestrial realm. Here, we provide a precisely-dated terrestrial record crossing the MECO time interval from the Xining Basin (NW China). We document a rapid aridification step and the onset of obliquity-dominated climate cyclicity indicated by lithofacies and pollen records dated at 40.0 Ma at the base of magnetochron C18n.2n. This shift is concomitant - within error - with the MECO peak warming in Ocean Drilling Program Site 1258 for which we reassessed the magnetostratigraphic age at 40.0 Ma (also at base of magnetochron C18n.2n). The rapidity of the shift observed in the Xining Basin and the region-wide aridification and monsoonal intensification reported around 40 Ma suggests Asian paleoenvironments were responding to global climate changes associated with the MECO. However, the Xining records show only the permanent shift but not the transient peak warming observed in marine MECO records. We thus relate this permanent aridification to occur during the post-MECO cooling. We propose the mechanisms linking global climate to Asian paleoenvironments may be eustatic fluctuations driving the stepwise retreat of the proto-Paratethys epicontinental sea or simply global cooling reducing moisture supply to the continental interior. In any case, Eocene global climate cooling from greenhouse to icehouse conditions seem to have played a primary role in shaping Asian paleoenvironments.
Pidgeon, C.; McNeely, S.; Schmidt, T.; Johnson, J.E.
1987-01-13
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.
Optimum design of bridges with superelastic-friction base isolators against near-field earthquakes
NASA Astrophysics Data System (ADS)
Ozbulut, Osman E.; Hurlebaus, Stefan
2010-04-01
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.
Loop-deformed Poincaré algebra
Jakub Mielczarek
2013-04-08
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.
Unimodular loop quantum cosmology
NASA Astrophysics Data System (ADS)
Chiou, Dah-Wei; Geiller, Marc
2010-09-01
Unimodular gravity is based on a modification of the usual Einstein-Hilbert action that allows one to recover general relativity with a dynamical cosmological constant. It also has the interesting property of providing, as the momentum conjugate to the cosmological constant, an emergent clock variable. In this paper we investigate the cosmological reduction of unimodular gravity, and its quantization within the framework of flat homogeneous and isotropic loop quantum cosmology. It is shown that the unimodular clock can be used to construct the physical state space, and that the fundamental features of the previous models featuring scalar field clocks are reproduced. In particular, the classical singularity is replaced by a quantum bounce, which takes place in the same condition as obtained previously. We also find that requirement of semiclassicality demands the expectation value of the cosmological constant to be small (in Planck units). The relation to spin foam models is also studied, and we show that the use of the unimodular time variable leads to a unique vertex expansion.
Two Loop QCD Vertices and Three Loop MOM $?$ functions
K. G. Chetyrkin; T. Seidensticker
2000-08-29
We present numerical results for the two loop QCD corrections to the ghost gluon vertex, the quark gluon vertex, and the triple gluon vertex in the massless limit at the symmetric point. We restrict ourselves to the tensor structures existing in the tree level. The corrections are used to examine different coupling constant definitions in momentum subtraction schemes and the corresponding three-loop $\\beta$ functions.
Bending of the looping heart: differential growth revisited.
Shi, Yunfei; Yao, Jiang; Xu, Gang; Taber, Larry A
2014-08-01
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
NASA Astrophysics Data System (ADS)
Kallus, Yoav
2014-03-01
The question of which convex shapes leave the most empty space in their densest packing is the subject of Reinhardt's conjecture in two dimensions and Ulam's conjecture in three dimensions. Such conjectures about pessimal packing shapes have proven notoriously difficult to make progress on. I show that the regular heptagon is a local pessimum among all convex shapes, and that the 3D ball is a local pessimum among origin-symmetric shapes. Any shape sufficiently close in the space of shapes to these local pessima can be packed at a greater efficiency than they. In two dimensions and in dimensions above three, the ball is not a local pessimum, so the situation in 3D is unusual and intriguing. I will discuss what conditions conspire to make the 3D ball a local pessimum and whether we can prove that it is also a global pessimum.
Shaped charge perforating device
Ayers, D.B.
1986-04-22
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.
Ultrafast optical pulse shaping
NASA Astrophysics Data System (ADS)
Agostinelli, J. A.
1980-03-01
A passive pulse shaping system and two active pulse shaping systems are constructed and tested experimentally. Each system is analyzed and the analytical and experimental results are compared. For the active systems, the ultimate risetimes are calculated for the particular active devices which are utilized. A fairly comprehensive review of the entire field of ultrafast pulse shaping is undertaken. The passive system incorporates a pair of diffraction gratings and various filtering operations. It produces pulses of arbitrary temporal intensity profile from short (mode locked Nd:YAG) input pulses. The shape resolution in the output pulse is of the order of the input pulsewidth. The shaped output pulse is shown to be linearly frequency modulated. With the largest gratings available commercially, total pulse lengths of about 2 ns appear to be possible. The active pulse shaping systems include linear electro-optic (Pockels cell) and nonlinear electro-optic (Kerr cell) modulators, each driven by light activated semiconductor switch circuitry.
Affective loop experiences: designing for interactional embodiment.
Höök, Kristina
2009-12-12
Involving our corporeal bodies in interaction can create strong affective experiences. Systems that both can be influenced by and influence users corporeally exhibit a use quality we name an affective loop experience. In an affective loop experience, (i) emotions are seen as processes, constructed in the interaction, starting from everyday bodily, cognitive or social experiences; (ii) the system responds in ways that pull the user into the interaction, touching upon end users' physical experiences; and (iii) throughout the interaction the user is an active, meaning-making individual choosing how to express themselves-the interpretation responsibility does not lie with the system. We have built several systems that attempt to create affective loop experiences with more or less successful results. For example, eMoto lets users send text messages between mobile phones, but in addition to text, the messages also have colourful and animated shapes in the background chosen through emotion-gestures with a sensor-enabled stylus pen. Affective Diary is a digital diary with which users can scribble their notes, but it also allows for bodily memorabilia to be recorded from body sensors mapping to users' movement and arousal and placed along a timeline. Users can see patterns in their bodily reactions and relate them to various events going on in their lives. The experiences of building and deploying these systems gave us insights into design requirements for addressing affective loop experiences, such as how to design for turn-taking between user and system, how to create for 'open' surfaces in the design that can carry users' own meaning-making processes, how to combine modalities to create for a 'unity' of expression, and the importance of mirroring user experience in familiar ways that touch upon their everyday social and corporeal experiences. But a more important lesson gained from deploying the systems is how emotion processes are co-constructed and experienced inseparable from all other aspects of everyday life. Emotion processes are part of our social ways of being in the world; they dye our dreams, hopes and bodily experiences of the world. If we aim to design for affective interaction experiences, we need to place them into this larger picture. PMID:19884153
Mcphee, W.A.
1983-06-14
A shaped charge unit is claimed for well perforating having a outer shell with an internal cavity formed therein. An explosive charge material conforms in exterior shape with the inside surface of the cavity and is retained in place by a conical liner of nonexplosive material. The interior shape of the cavity is such that an increased amount of explosive material is provided in a circumferential channel located proximate to the periphery of the base of the conical liner.
Andreas Lendlein; Steffen Kelch
2002-01-01
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
Keynote lecture: shape interrogation
Nicholas M. Patrikalakis
2003-01-01
Shape interrogation is the process of extraction of informationfrom a geometric model. It is a fundamental component of CAD\\/CAMsystems. In this lecture, we focus on shape interrogation ofgeometric models bounded by free-form or sculptured surfaces. Suchsurfaces are widely used in the bodies of ships, automobiles,aircraft, propeller and turbine blades, and various consumerdevices. Our basic thesis is that shape interrogation problems
S. Büttgenbach; S. Bütefisch; M. Leester-Schädel; A. Wogersien
2001-01-01
Since shape memory alloys have been recognized to be a smart material, actuator elements based on the shape memory effect\\u000a have been increasingly used in various fields of application. This paper reports on the design and fabrication of several\\u000a silicon microactuators driven by shape memory elements, namely mechanical microgrippers, microvalves and artificial muscle\\u000a actuators. The actuators were designed as compliant
Arbitrary Dimensional Loop Quantum Cosmology
Zhang, Xiangdong
2015-01-01
Loop quantum cosmology(LQC) is the symmetric model of loop quantum gravity. In this paper, we generalize the structure of loop quantum cosmology to the theories with arbitrary spacetime dimensions. The isotropic and homogenous cosmological model in n+1 dimensions is quantized by the loop quantization method. Interestingly, we find that the underlying quantum theories are divided into two qualitatively different sectors according to spacetime dimensions. The effective Hamiltonian and modified dynamical equations of n+1 dimensional LQC are obtained. Moreover, our results indicate that the classical big bang singularity is resolved in arbitrary spacetime dimensions by a quantum bounce. We also briefly discuss the similarities and differences between the n+1 dimensional model and the 3+1 dimensional one.
Automatic blocking of nested loops
NASA Technical Reports Server (NTRS)
Schreiber, Robert; Dongarra, Jack J.
1990-01-01
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.
N. Nakazawa
1995-08-22
We apply stochastic quantization method to matrix models for the second quantization of loops in both discretized and continuum levels. The fictitious time evolution described by the Langevin equation is interpreted as the time evolution in a field theory of loops. The corresponding Fokker-Planck hamiltonian defines a non-critical string field theory. We study both orientable and non-orientable interactions of loops in terms of matrix models and take the continuum limit for one-matrix case. As a consequence, we show the equivalence of stochastic quantization of matrix models in loop space to the transfer-matrix formalism in dynamical triangulation of random surfaces. We also clarifies the origin of Virasoro algebra in this context.
Arbitrary Dimensional Loop Quantum Cosmology
Xiangdong Zhang
2015-06-18
Loop quantum cosmology(LQC) is the symmetric model of loop quantum gravity. In this paper, we generalize the structure of loop quantum cosmology to the theories with arbitrary spacetime dimensions. The isotropic and homogenous cosmological model in n+1 dimensions is quantized by the loop quantization method. Interestingly, we find that the underlying quantum theories are divided into two qualitatively different sectors according to spacetime dimensions. The effective Hamiltonian and modified dynamical equations of n+1 dimensional LQC are obtained. Moreover, our results indicate that the classical big bang singularity is resolved in arbitrary spacetime dimensions by a quantum bounce. We also briefly discuss the similarities and differences between the n+1 dimensional model and the 3+1 dimensional one.
Induction loop detector systems crosstalk
Bhagat, Victor
1994-01-01
traffic control systems are necessary to obtain maximum possible efficiency from our freeway systems. A major component of freeway management systems is the induction loop detector. This research effort evaluated the methods by which crosstalk could...
M. J. G. Veltman; G.'t Hooft
1979-01-01
The completely general one-loop scalar one-, two-, three- and four-point functions\\u000aare studied. Also an integral occurring in connection with soft bremsstrahlung is considered.\\u000aFormulas in terms of Spence functions are given. An expansion for Spence\\u000afunctions with complex argument is presented. The whole forms a basis for the calculation\\u000aof one-loop radiative corrections in the general case, including unstable
G.'t Hooft; M. Veltman
1979-01-01
The completely general one-loop scalar one-, two-, three- and four-point functions are studied. Also an integral occurring in connection with soft bremsstrahlung is considered. Formulas in terms of Spence functions are given. An expansion for Spence functions with complex argument is presented. The whole forms a basis for the calculation of one-loop radiative corrections in the general case, including unstable
Introduction to Loop Quantum Gravity
Simone Mercuri
2010-01-08
The questions I have been asked during the 5th International School on Field Theory and Gravitation, have compelled me to give an account of the premises that I consider important for a beginner's approach to Loop Quantum Gravity. After a description of some general arguments and an introduction to the canonical theory of gravity, I review the background independent approach to quantum gravity, giving only a brief survey of Loop Quantum Gravity.
Kalibjian, R.; Chong, Y.P.; Prono, D.S.; Cavagnolo, H.R.
1984-06-01
The ATA provides an electron beam pulse of 70-ns duration at a 1-Hz rate. Our present optical diagnostics technique involve the imaging of the visible light generated by the beam incident onto the plant of a thin sheet of material. It has already been demonstrated that the light generated has a sufficiently fast temporal reponse in performing beam diagnostics. Notwithstanding possible beam emittance degradation due to scattering in the thin sheet, the observation of beam spatial profiles with relatively high efficiencies has provided data complementary to that obtained from beam wall current monitors and from various x-ray probes and other electrical probes. The optical image sensor consists of a gated, intensified television system. The gate pulse of the image intensifier can be appropriately delayed to give frames that are time-positioned from the head to the tail of the beam with a minimum gate time of 5-ns. The spatial correlation of the time frames from pulse to pulse is very good for a stable electron beam; however, when instabilities do occur, it is difficult to properly assess the spatial composition of the head and the tail of the beam on a pulse-to-pulse basis. Multiple gating within a pulse duration becomes desirable but cannot be performed because the recycle time (20-ms) of the TV system is much longer than the beam pulse. For this reason we have developed an optical-loop framing technique that will allow the recording of two frames within one pulse duration with our present gated/intensified TV system.
High temperature loop heat pipes
Anderson, W.G.; Bland, J.J. [Thermacore, Inc., Lancaster, PA (United States); Fershtater, Y.; Goncharov, K.A.; Nikitkin, M. [TAIS, Inc., Moscow (Russian Federation); Juhasz, A. [NASA Lewis Research Center, Cleveland, OH (United States)
1995-12-31
Advantages of loop heat pipes over conventional heat pipes include self-priming during start-up, improved tolerance for noncondensible gas, and ability for ground testing in any orientation. The applications for high temperature, alkali-metal working fluid loop heat pipes include space radiators, and bimodal systems. A high temperature loop heat pipe was fabricated and tested at 850 K, using cesium as the working fluid. Previous loop heat pipes were tested with ambient temperature working fluids at temperatures below about 450 K. The loop heat pipe had a titanium envelope, and a titanium aluminide wick. The maximum cesium loop heat pipe power was only about 600 watts, which was lower the predicted 1,000 W power. The power limitation may be due to a wettability problem with the cesium not completely wetting the titanium aluminide wick. This would reduce the pumping capability of the wick, and the maximum power that the heat pipe could carry. This problem could be solved by using a refractory metal powder wick, since the alkali metals are known to wet refractory metal wicks.
Optimum Projection Angle for Attaining Maximum Distance in a Soccer Punt Kick
Linthorne, Nicholas P.; Patel, Dipesh S.
2011-01-01
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 player’s 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 player’s 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
Experimental investigation of penetration performance of shaped charge into concrete targets
NASA Astrophysics Data System (ADS)
Wang, Cheng; Ma, Tianbao; Ning, Jianguo
2008-06-01
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.
Research and recommendation of optimum group synchronization codes for N = 7-32
NASA Astrophysics Data System (ADS)
Lei, Zhongkui; Xie, Qiucheng; Cao, Jie
The present work has been prompted by the perception that some of the codes in the IRIG Telemetry Standards are of equivocal optimality, that the application conditions for optimum codes were not fully expounded, and that a need has been created for greater transmission capacity in PCM communications where optimum codes are of length greater than 30. A set of edited tables is accordingly provided for Optimum Group Synchronization Codes of length N = 7-32. The optimality of the codes is conditional, and changes with error tolerance.
Free loop spaces in topology and
Thévenaz, Jacques
Free loop spaces in topology and physics Kathryn Hess What is the space of free loops? Enumeration of geodesics Hochschild and cyclic homology Homological conformal field theories Free loop spaces in topology Meeting of the Edinburgh Mathematical Society Glasgow, 14 November 2008 #12;Free loop spaces in topology
Global stabilization of a thermal convection loop
Dejan M. Boskovic; Miroslav Krstic
2000-01-01
A nonlinear feedback control law that achieves global asymptotic stabilization of a 2D thermal convection loop is presented. The loop consists of a viscous Newtonian fluid contained in between two concentric cylinders standing in a vertical plane. The lower half of the loop is heated while the upper half is cooled. Stability analysis of the thermal convection loop shows that
Lower 48's only superport: LOOP
1984-01-01
Historical aspects, constraints, and the operation of Louisiana's Offshore Oil Port (LOOP) are discussed. The facility is described as well as onshore storage and handling facilities and pipelines servicing LOOP. Similarities between LOOP and the Trans Alaska Pipeline System (TAPS) are described. TAPS and LOOP were the US petroleum industry's two biggest projects in the 1970's.
Shape memory polymer nanocomposites
Ken Gall; Martin L. Dunn; Yiping Liu; Dudley Finch; Mark Lake; Naseem A. Munshi
2002-01-01
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
Abhijit Bhattacharyya; Dimitris C Lagoudas
2007-01-01
This special issue on shape memory alloys (SMA) is an encore to a special issue on the same topic edited by us six years ago (Smart Mater. Struct.9 (5) October 2000). A total of 19 papers is offered in this issue, organized into the three broad categories of modeling, characterization and applications. In addition to thermally activated shape memory alloys,
W. A. Lorenz; Yann Ponty; Peter Clote
2008-01-01
RNA shapes, introduced by Giegerich et al. (17), pro- vide a useful classiflcation of the branching complexity for RNA secondary structures. In this paper, we derive an exact value for the asymptotic number of RNA shapes, by relying on an elegant relation between non-ambiguous, context-free grammars and gen- erating functions. Our results provide a theoretical upper bound on the length
NSDL National Science Digital Library
2012-08-23
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.
Exploration trees and conformal loop ensembles
Scott Sheffield
2006-11-23
We construct and study the conformal loop ensembles CLE(kappa), defined for all kappa between 8/3 and 8, using branching variants of SLE(kappa) called exploration trees. The conformal loop ensembles are random collections of countably many loops in a planar domain that are characterized by certain conformal invariance and Markov properties. We conjecture that they are the scaling limits of various random loop models from statistical physics, including the O(n) loop models.
The 21 cm signature of a cosmic string loop
Pagano, Michael; Brandenberger, Robert, E-mail: paganom@physics.mcgill.ca, E-mail: rhb@physics.mcgill.ca [Department of Physics, McGill University, 3600 Rue University, Montréal, QC, H3A 2T8 (Canada)
2012-05-01
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.
A MONTE CARLO SEQUENTIAL ESTIMATION OF POINT PROCESS OPTIMUM FILTERING FOR BRAIN MACHINE INTERFACES
Slatton, Clint
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
Optimum wall impedance for spinning modes - A correlation with mode cut-off ratio
E. J. Rice
1978-01-01
A correlating equation relating the optimum acoustic impedance for the wall lining of a circular duct to the acoustic mode cut-off ratio is presented and compared to exact calculations. The optimum impedance was correlated with cut-off ratio because the cut-off ratio appears to be the fundamental parameter governing the propagation of sound in the duct. Modes with similar cut-off ratios
Marshall, Kelly Lynn
2001-01-01
TIMED APPLICATION OF AMMONIUM NITRATE FOR OPTIMUM YIELD OF UNIFORM SWEETPOTATO (/pomoea beta/as ) TUBEROUS ROOTS A Thesis by KELLY LYNN MARSHALL Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE May 2001 Major Subject Plant Breeding TIMED APPLICATION OF AMMONIUM NITRATE FOR OPTIMUM YIELD OF UNIFORM SWEETPOTATO (IPOMOEA BATATAS) TUBEROUS ROOTS A Thesis By KELLY LYNN MARSHALL Submitted to Texas...
Loyka, Sergey
IEEE TRANSACTIONS ON COMMUNICATIONS, VOL. 59, NO. 3, MARCH 2011 877 Optimum Power and Rate. Compact, closed-form expressions for the optimum allocations and corresponding system performance are given. The uniform power allocation is shown to be near optimum in the low outage regime in combination
NASA Astrophysics Data System (ADS)
Peng, Huabei; Song, Fan; Wang, Shanling; Zhang, Chengyan; Wen, Yuhua
2015-05-01
To clarify the role of carbon in improving the shape memory effect of Fe–Mn–Si-based shape memory alloys by thermomechanical treatments, we investigated the effect of optimum thermomechanical treatments on shape memory effect and microstructures of Fe–14Mn–5Si–8Cr–4Ni and Fe–14Mn–5Si–8Cr–4Ni–0.12C alloys. The Cr23C6 particles in optimum thermomechanical-treated Fe–14Mn–5S–8Cr–4Ni–0.12C more effectively prevented collisions between stress-induced ? martensite bands than the residual ?? martensite in optimum thermomechanical-treated Fe–14Mn–5Si–8Cr–4Ni. This result is attributed to the thinner width of stress-induced ? martensite bands in optimum thermomechanical-treated Fe–14Mn–5S–8Cr–4Ni–0.12C compared to optimum thermomechanical-treated Fe–14Mn–5Si–8Cr–4Ni. In addition, the Cr23C6 particles formed at more sites and provided more obstacles as compared with the residual ?? martensite. Accordingly, the recovery strain of Fe–14Mn–5Si–8Cr–4Ni–0.12C was higher than that of Fe–14Mn–5Si–8Cr–4Ni. It is concluded that carbon addition is beneficial to further improving the shape memory effect of Fe–Mn–Si-based shape memory alloys by thermomechanical treatments.
Approximately global optimization for robust alignment of generalized shapes.
Li, Hongsheng; Shen, Tian; Huang, Xiaolei
2011-06-01
In this paper, we introduce a novel method to solve shape alignment problems. We use gray-scale "images" to represent source shapes, and propose a novel two-component Gaussian Mixture (GM) distance map representation for target shapes. This asymmetric representation is a flexible image-based representation which is able to represent different kinds of shape data, including continuous contours, unstructured sparse point sets, edge maps, and even gray-scale gradient maps. Using this representation, a new energy function based on a novel two-component Gaussian Mixture distance model is proposed. The new energy function was empirically evaluated to be a more robust shape dissimilarity metric that can be computed efficiently. Such high efficiency is essential for global optimization methods. We adopt and modify one of them, the Particle Swarm Optimization (PSO), to effectively estimate the global optimum of the new energy function. Differently from the original PSO, several new strategies were employed to make the optimization more robust and prevent it from converging prematurely. The overall performance of the proposed framework as well as the properties of each algorithmic component were evaluated and compared with those of some state-of-the-art methods. Extensive experiments and comparison performed on generalized 2D and 3D shape data demonstrate the robustness and effectiveness of the method. PMID:20820077
Inferring the in vivo looping properties of DNA
Leonor Saiz; J. Miguel Rubi; Jose M. G. Vilar
2005-12-20
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.
Huey-Ru Chuang; Wen-Tzu Chen
1997-01-01
In this paper, numerical simulation of the influence of the human body on the antenna radiation characteristics, such as input impedance, current distribution, radiation pattern, and directive gain, of a circular loop with arbitrary orientation relative to the human body is presented. A 3-D realistically shaped man model (175-cm height) with homogenous muscle phantom is constructed. Coupled integral equations (CIE),
Fast and Incremental Method for Loop-Closure Detection Using Bags of Visual Words
Adrien Angeli; David Filliat; Stéphane Doncieux; Jean-arcady Meyer
2008-01-01
In robotic applications of visual simultaneous lo- calization and mapping techniques, loop-closure detection and global localization are two issues that require the capacity to recognize a previously visited place from current camera measurements. We present an online method that makes it possible to detect when an image comes from an already perceived scene using local shape and color information. Our
Open-loop control of a MEMS deformable mirror for large-amplitude wavefront control
Open-loop control of a MEMS deformable mirror for large-amplitude wavefront control Jason B for predicting control voltages that will generate a prescribed surface shape on a MEMS deformable mirror.4460, 000.2170. 1. INTRODUCTION The use of microelectromechanical systems (MEMS) de- formable mirrors (DMs
Wide-band matched amplifier design using dual loop feedback and two common emitter transistor stages
THOMAS J. APRILLE
1976-01-01
This paper gives practical synthesis procedures for the design of shaped gain, wide-band, matched, dual loop feedback amplifiers that use a cascade of two common emitter transistor stages. These procedures are unique in that loading effects of the feedback networks are fully taken into account. A comparison example is constructed that shows this technique to be more than a viable
Hyperbolically shaped centrifugal compressor
NASA Astrophysics Data System (ADS)
Puzyrewski, Romuald; Flaszy?ski, Pawel
2003-08-01
Starting from the classical centrifugal compressor, cone shaped in meridional cross section, two modifications are considered on the basis of results from 2D and 3D flow models. The first modification is the change of the meridional cross section to hyperbolically shaped channel. The second modification, proposed on the basis of 2D axisymmetric solution, concerns the shape of blading. On the strength of this solution the blades are formed as 3D shaped blades, coinciding with the recent tendency in 3D designs. Two aims were considered for the change of meridional compressor shape. The first was to remove the separation zone which appears as the flow turns from axial to radial direction. The second aim is to uniformize the flow at exit of impeller. These two goals were considered within the frame of 2D axisymmetric model. Replacing the cone shaped compressor by a hyperbolically shaped one, the separation at the corner was removed. The disc and shroud shape of the compressor was chosen in the way which satisfies the condition of most uniform flow at the compressor exit. The uniformity of exit flow from the rotor can be considered as the factor which influences the performance of the diffuser following the rotor. In the 2D model a family of stream surfaces of S 1 type is given in order to find S 2 surfaces which may be identified with the midblade surfaces of compressor blading. A computation of 3D type has been performed in order to establish the relations between 2D and 3D models in the calculation of flow parameters. In the presented example the 2D model appears as the inverse model which leads to 3D shape of blading whereas the 3D model has been used for the direct solution. In the presented example the confrontation of two models, 2D and 3D, leads to a better understanding of the application of these models to the design procedure.
Hardware-Based Non-Optimum Factors for Launch Vehicle Structural Design
NASA Technical Reports Server (NTRS)
Wu, K. Chauncey; Cerro, Jeffrey A.
2010-01-01
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.
NSDL National Science Digital Library
Twin Cities Public Television, Inc.
2006-01-01
In this activity (on page 2 of the PDF), learners will discover how the shape of an object, not just its weight, determines whether it floats or sinks. After a ball of aluminum foil sinks in a bucket of water, the ball is opened up into a flat sheet that learners will shape into a sided tray or another shape they may come up with, then placed back in the bucket. If it floats, carefully add pennies until it sinks. Relates to the linked video, DragonflyTV GPS: Sailboat Design.
NASA Astrophysics Data System (ADS)
Kasdin, N. Jeremy; Vanderbei, Robert J.; Belikov, Ruslan
2007-04-01
At Princeton we have been studying shaped pupil coronagraphs for high contrast imaging and planet finding. These will find applications in both ground and space imaging. In this article we summarize the design procedure for shaped pupils and review the various families of designs we have found. We describe the manufacturing processes we have used to make free standing shaped pupil masks and review our most recent laboratory results with and without wavefront control. We also discuss the factors limiting high contrast in the laboratory and our plans for mitigating them. To cite this article: N.J. Kasdin et al., C. R. Physique 8 (2007).
NASA Technical Reports Server (NTRS)
Thomas, Jr., Jess B. (Inventor)
1991-01-01
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.
NSDL National Science Digital Library
National Council of Teachers of Mathematics
2008-01-01
In this math lesson, learners read the poem "Shapes" from "A Light in the Attic" by Shel Silverstein. Then, learners create their own illustration of the poem. In this lesson, learners explore geometric figures and positional words.
Electrostatically shaped membranes
NASA Technical Reports Server (NTRS)
Silverberg, Larry M. (Inventor)
1994-01-01
Disclosed is a method and apparatus for electrostatically shaping a membrane suitable for use in antennas or the like, comprising an electrically conductive thin membrane where the periphery of said membrane is free to move in at least one direction, a first charge on the electrically conductive thin membrane to electrostatically stiffen the membrane, a second charge which shapes the electrostatically stiffened thin membrane and a restraint for limiting the movement of at least one point of the thin membrane relative to the second charge. Also disclosed is a method and apparatus for adaptively controlling the shape of the thin membrane by sensing the shape of the membrane and selectively controlling the first and second charge to achieve a desired performance characteristic of the membrane.
Freeman, William T.
2002-01-10
We introduce a new method to describe, in a single image, changes in shape over time. We acquire both range and image information with a stationary stereo camera. From the pictures taken, we display a composite image ...
NSDL National Science Digital Library
How much liquid can that glass hold? What are the dimensions of that package that's heading off to a friend overseas? Answers to both of those questions (and many more) can be found in this lovely interactive feature on 3D shapes created by experts at the Annenberg Media group. Visitors to this site will learn about three-dimensional geometric shapes by examining a number of objects through a number of interactive exercises and games. The materials are divided into four sections, which include "3D Shapes", "Surface Area & Volume", and "Platonic Solids". The "Platonic Solids" area is quite a bit of fun, as visitors will get the opportunity to print out foldable shapes such as a tetrahedron. A short fifteen question quiz that tests the materials covered by these various activities rounds out the site.
Millennial-scale vegetation dynamics in an estuary at the onset of the Miocene Climate Optimum
Kern, Andrea; Harzhauser, Mathias; Mandic, Oleg; Roetzel, Reinhard; ?ori?, Stjepan; Bruch, Angela A.; Zuschin, Martin
2010-01-01
Pollen analyses have been proven to possess the possibility to decipher rapid vegetational and climate shifts in Neogene sedimentary records. Herein, a c. 21-kyr-long transgression–regression cycle from the Lower Austrian locality Stetten is analysed in detail to evaluate climatic benchmarks for the early phase of the Middle Miocene Climate Optimum and to estimate the pace of environmental change. Based on the Coexistence Approach, a very clear signal of seasonality can be reconstructed. A warm and wet summer season with c. 204–236 mm precipitation during the wettest month was opposed by a rather dry winter season with precipitation of c. 9–24 mm during the driest month. The mean annual temperature ranged between 15.7 and 20.8 °C, with about 9.6–13.3 °C during the cold season and 24.7–27.9 °C during the warmest month. In contrast, today’s climate of this area, with an annual temperature of 9.8 °C and 660 mm rainfall, is characterized by the winter season (mean temperature: ?1.4 °C, mean precipitation: 39 mm) and a summer mean temperature of 19.9 °C (mean precipitation: 84 mm). Different modes of environmental shifts shaped the composition of the vegetation. Within few millennia, marshes and salt marshes with abundant Cyperaceae rapidly graded into Taxodiaceae swamps. This quick but gradual process was interrupted by swift marine ingressions which took place on a decadal to centennial scale. The transgression is accompanied by blooms of dinoflagellates and of the green alga Prasinophyta and an increase in Abies and Picea. Afterwards, the retreat of the sea and the progradation of estuarine and wetland settings were a gradual progress again. Despite a clear sedimentological cyclicity, which is related to the 21-kyr precessional forcing, the climate data show little variation. This missing pattern might be due to the buffering of the precessional-related climate signal by the subtropical vegetation. Another explanation could be the method-inherent broad range of climate-parameter estimates that could cover small scale climatic changes. PMID:22021937
Study of one-dimensional electron hopping and its effects on ESR line shape
Tang, Jau [Argonne National Lab., IL (United States); Dikshit, S.N. [Univ. of Chicago, IL (United States). Dept. of Chemistry; Norris, J.R. [Argonne National Lab., IL (United States)]|[Univ. of Chicago, IL (United States). Dept. of Chemistry
1997-08-01
Random hopping processes between discrete sites along a finite open chain or around a closed finite loop are examined. Closed form formulae are prescribed for the dependence of the ESR (electron spin resonance) line shape on the chain length and hopping rate. Significant differences between the closed loop and open chain are demonstrated. Deviation at short time from the results of diffusion in a continuum is presented.
Czajka, Alina
2015-01-01
The effective actions of gauge bosons, fermions and scalars, which are obtained within the hard-loop approximation, are shown to have unique forms for a whole class of gauge theories including QED, scalar QED, super QED, pure Yang-Mills, QCD, super Yang-Mills. The universality occurs irrespective of a field content of each theory and of variety of specific interactions. Consequently, the long-wavelength or semiclassical features of plasma systems governed by these theories such as collective excitations are almost identical. An origin of the universality, which holds within the limits of applicability of the hard-loop approach, is discussed.
Alina Czajka; Stanislaw Mrowczynski
2015-05-29
The effective actions of gauge bosons, fermions and scalars, which are obtained within the hard-loop approximation, are shown to have unique forms for a whole class of gauge theories including QED, scalar QED, super QED, pure Yang-Mills, QCD, super Yang-Mills. The universality occurs irrespective of a field content of each theory and of variety of specific interactions. Consequently, the long-wavelength or semiclassical features of plasma systems governed by these theories such as collective excitations are almost identical. An origin of the universality, which holds within the limits of applicability of the hard-loop approach, is discussed.
NASA Astrophysics Data System (ADS)
Tatartchenko, Vitali A.
Crystals of specified shape and size (shaped crystals) with controlled defect and impurity structure have to be grown for the successful development of modern engineering. Since the 1950s many hundreds of papers and patents concerned with shaped growth have been published. In this chapter, we do not try to enumerate the successful applications of shaped growth to different materials but rather to carry out a fundamental physical and mathematical analysis of shaping as well as the peculiarities of shaped crystal structures. Four main techniques, based on which the lateral surface can be shaped without contact with the container walls, are analyzed: the Czochralski technique (CZT), the Verneuil technique (VT), the floating zone technique (FZT), and technique of pulling from shaper (TPS). Modifications of these techniques are analyzed as well. In all these techniques the shape of the melt meniscus is controlled by surface tension forces, i.e., capillary forces, and here they are classified as capillary shaping techniques (CST). We look for conditions under which the crystal growth process in each CST is dynamically stable. Only in this case are all perturbations attenuated and a crystal of constant cross section grown without any special regulation. The dynamic stability theory of the crystal growth process for all CST is developed on the basis of Lyapunov's dynamic stability theory. Lyapunov's equations for the crystal growth processes follow from fundamental laws. The results of the theory allow the choice of stable regimes for crystal growth by all CST as well as special designs of shapers in TPS. SCG experiments by CZT, VT, and FZT are discussed but the main consideration is given to TPS. Shapers not only allow crystal of very complicated cross section to be grown but provide a special distribution of impurities. A history of TPS is provided later in the chapter, because it can only be described after explanation of the fundamental principles of shaping. Some shaped crystals, especially sapphire and silicon, have specified structures. The crystal growth of these materials, and some metals, including crystal growth in space, is discussed.
Shape Stylized Face Caricatures
Nguyen Kim Hai Le; Why Yong Peng; Golam Ashraf
2011-01-01
\\u000a Facial caricatures exaggerate key features to emphasize unique structural and personality traits. It is quite a challenge\\u000a to retain the identity of the original person despite the exaggerations. We find that primitive shapes are well known for\\u000a representing certain personality traits, in art and psychology literature. Unfortunately, current automated caricature generation\\u000a techniques ignore the role of primitive shapes in stylization.
Non-Gaussian features from the inverse volume corrections in loop quantum cosmology
NASA Astrophysics Data System (ADS)
Li, Li-Fang; Cai, Rong-Gen; Guo, Zong-Kuan; Hu, Bin
2012-08-01
In this paper we study the non-Gaussian features of the primordial fluctuations in loop quantum cosmology with the inverse volume corrections. The detailed analysis is performed in the single field slow-roll inflationary models. However, our results reflect the universal characteristics of bispectrum in loop quantum cosmology. The main corrections to the scalar bispectrum come from two aspects: one is the modifications to the standard Bunch-Davies vacuum, and the other is the corrections to the background dependent variables, such as slow-roll parameters. Our calculations show that the loop quantum corrections make fNL of the inflationary models increase 0.1%. Moreover, we find that two new shapes of non-Gaussian signal arise, which we name F1 and F2. The former gives a unique loop quantum feature, which is less correlated with the local, equilateral, and single types, while the latter is highly correlated with the local one.
On Characterizing Particle Shape
NASA Technical Reports Server (NTRS)
Ennis, Bryan J.; Rickman, Douglas; Rollins, A. Brent; Ennis, Brandon
2014-01-01
It is well known that particle shape affects flow characteristics of granular materials, as well as a variety of other solids processing issues such as compaction, rheology, filtration and other two-phase flow problems. The impact of shape crosses many diverse and commercially important applications, including pharmaceuticals, civil engineering, metallurgy, health, and food processing. Two applications studied here include the dry solids flow of lunar simulants (e.g. JSC-1, NU-LHT-2M, OB-1), and the flow properties of wet concrete, including final compressive strength. A multi-dimensional generalized, engineering method to quantitatively characterize particle shapes has been developed, applicable to both single particle orientation and multi-particle assemblies. The two-dimension, three dimension inversion problem is also treated, and the application of these methods to DEM model particles will be discussed. In the case of lunar simulants, flow properties of six lunar simulants have been measured, and the impact of particle shape on flowability - as characterized by the shape method developed here -- is discussed, especially in the context of three simulants of similar size range. In the context of concrete processing, concrete construction is a major contributor to greenhouse gas production, of which the major contributor is cement binding loading. Any optimization in concrete rheology and packing that can reduce cement loading and improve strength loading can also reduce currently required construction safety factors. The characterization approach here is also demonstrated for the impact of rock aggregate shape on concrete slump rheology and dry compressive strength.
Looping of anisotropic, short double-stranded DNA
NASA Astrophysics Data System (ADS)
Kim, Harold; Le, Tung
2013-03-01
Bending of double-stranded DNA (dsDNA) is associated with fundamental biological processes such as genome packaging and gene regulation, and therefore studying sequence-dependent dsDNA bending is a key to understanding biological impact of DNA sequence beyond the genetic code. Average mechanical behavior of long dsDNA is well described by the wormlike chain model, but sequence-dependent anisotropic bendability and bendedness of dsDNA can in principle lead to abnormally high looping probability at short length scales. Here, we measured the looping probability density (J factor) and kinetics of dsDNA as a function of length and curvature using single-molecule FRET (Förster Resonance Energy Transfer). For theoretical comparison, we calculated the J-factor using a discrete dinucleotide chain model, and also simulated it by Monte Carlo methods. We provide evidences that even when the intrinsic shape of dsDNA is accounted for, the wormlike chain model fails to describe looping dynamics of dsDNA below 200-bp length scale. Bending of double-stranded DNA (dsDNA) is associated with fundamental biological processes such as genome packaging and gene regulation, and therefore studying sequence-dependent dsDNA bending is a key to understanding biological impact of DNA sequence beyond the genetic code. Average mechanical behavior of long dsDNA is well described by the wormlike chain model, but sequence-dependent anisotropic bendability and bendedness of dsDNA can in principle lead to abnormally high looping probability at short length scales. Here, we measured the looping probability density (J factor) and kinetics of dsDNA as a function of length and curvature using single-molecule FRET (Förster Resonance Energy Transfer). For theoretical comparison, we calculated the J-factor using a discrete dinucleotide chain model, and also simulated it by Monte Carlo methods. We provide evidences that even when the intrinsic shape of dsDNA is accounted for, the wormlike chain model fails to describe looping dynamics of dsDNA below 200-bp length scale. Georgia Tech FIRE program
[MRO] Oligocrystalline Shape Memory Alloys
Chen, Ying
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 ...
Recovery of solitons with nonlinear amplifying loop mirrors
NASA Astrophysics Data System (ADS)
Gabitov, Ildar; Holm, Darryl D.; Luce, Benjamin P.; Mattheus, Arnold
1995-12-01
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.
Shape memory polymer medical device
Maitland, Duncan (Pleasant Hill, CA); Benett, William J. (Livermore, CA); Bearinger, Jane P. (Livermore, CA); Wilson, Thomas S. (San Leandro, CA); Small, IV, Ward (Livermore, CA); Schumann, Daniel L. (Concord, CA); Jensen, Wayne A. (Livermore, CA); Ortega, Jason M. (Pacifica, CA); Marion, III, John E. (Livermore, CA); Loge, Jeffrey M. (Stockton, CA)
2010-06-29
A system for removing matter from a conduit. The system includes the steps of passing a transport vehicle and a shape memory polymer material through the conduit, transmitting energy to the shape memory polymer material for moving the shape memory polymer material from a first shape to a second and different shape, and withdrawing the transport vehicle and the shape memory polymer material through the conduit carrying the matter.
Parts Orienting with Shape Uncertainty
Srinivas Akella; Matthew T. Mason
1998-01-01
Abstract Parts manufactured,to tolerances have shape variations. Most work in robotic manipulation,assumes,that part shape does not vary. Orienting devices such as bowl feeders frequently fail due to variations in part shape. In this paper we develop techniques to orient parts with shape uncertainty. We present a shape uncertainty model and describe the nondeterminism,in parts orienting that arises from shape uncertainty.
Microcatheter Looping to Facilitate Aneurysm Selection in Coil Embolization of Paraclinoid Aneurysms
Cho, Young Dae; Rhim, Jong Kook; Park, Jeong Jin; Jeon, Jin Sue; Yoo, Roh-Eul; Kim, Jeong Eun; Cho, Won-Sang; Han, Moon Hee
2015-01-01
Objective Described herein is a microcatheter looping technique to facilitate aneurysm selection in paraclinoid aneurysms, which remains to be technically challenging due to the inherent complexity of regional anatomy. Materials and Methods This retrospective study was approved by our Institutional Review Board, and informed consent was waived. Microcatheter looping method was employed in 59 patients with paraclinoid aneurysms between January 2012 and December 2013. In the described technique, construction of a microcatheter loop, which is steam-shaped or pre-shaped, based on the direction of aneurysms, is mandatory. The looped tip of microcatheter was advanced into distal internal carotid artery and positioned atop the target aneurysm. By steering the loop (via inner microguidewire) into the dome of aneurysm and easing tension on the microcatheter, the aneurysm was selected. Clinical and morphologic outcomes were assessed with emphasis on technical aspects of the treatment. Results Through this looping technique, a total of 59 paraclinoid aneurysms were successfully treated. After aneurysm selection as described, single microcatheter technique (n = 25) was most commonly used to facilitate coiling, followed by balloon protection (n = 21), stent protection (n = 7), multiple microcatheters (n = 3), and stent/balloon combination (n = 3). Satisfactory aneurysmal occlusion was achieved through coil embolization in 44 lesions (74.6%). During follow-up of 53 patients (mean interval, 10.9 ± 5.9 months), only one instance (1.9%) of major recanalization was observed. There were no complications related to microcatheter looping. Conclusion This microcatheter looping method facilitates safe and effective positioning of microcatheter into domes of paraclinoid aneurysms during coil embolization when other traditional microcatheter selection methods otherwise fail. PMID:26175591
Loop quantum gravity and observations
A. Barrau; J. Grain
2014-10-07
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.
Quaternion-Loop Quantum Gravity
M. D. Maia; S. S. e Almeida Silva; F. S. Carvalho
2009-09-24
It is shown that the Riemannian curvature of the 3-dimensional hypersurfaces in space-time, described by the Wilson loop integral, can be represented by a quaternion quantum operator induced by the SU(2) gauge potential, thus providing a justification for quaternion quantum gravity at the Tev energy scale.
On the saddle loop bifurcation
Freddy Dumortier; Robert Roussarie
It is shown that the set of C? (generic) saddle loop bifurcations has a unique modulus of stability ? ?]0, 1[?]1, ?[ for (C0, Cr)-equivalence, with 1?r??. We mean for an equivalence (x,?) ? (h(x,?), ?(?)) with h continuous and ? of class Cr. The modulus ? is the ratio of hyperbolicity at the saddle point of the connection. Already
Emphysema surgery – loop ligation approach
Hui-Ping Liu; Chau-Hsiung Chang; PyngJing Lin; Ka-Shun Cheng; Yi-Chen Wu; Yun-Hen Liu
1999-01-01
Objectives: To demonstrate the efficacy of using thoracoscopic endoloop ligation of bullae in patients with bullous emphysema. Methods: From 1992 to 1997, 93 advanced age (mean age, 66 years) and oxygen dependency patients underwent thoracoscopic procedure using endoloop ligation for treatment of bullous emphysema. Clinical data were collected from chart review. Thoracoscopic loop ligation of bulla was carried out under
Parallel MATLAB: Parallel For Loops
Crawford, T. Daniel
Parallel MATLAB: Parallel For Loops John Burkardt (FSU) Gene Cliff (AOE/ICAM - ecliff Research Computing ICAM: Interdisciplinary Center for Applied Mathematics 1 / 69 #12;MATLAB Parallel Example ODE SWEEP Example FMINCON Example Conclusion 2 / 69 #12;INTRO: Parallel MATLAB Parallel MATLAB
Automorphisms in loop quantum gravity
Benjamin Bahr; Thomas Thiemann
2009-01-01
We investigate a certain distributional extension of the group of spatial diffeomorphisms in loop quantum gravity. This extension, which is given by the automorphisms \\\\mathcal {A}{\\\\it ut}(\\\\mathcal {P}) of the path groupoid \\\\mathcal {P}, was proposed by Velhinho and is inspired by category theory. These automorphisms have much larger orbits than piecewise analytic diffeomorphisms. In particular, we will show that
Closed loop solar collector system
1981-01-01
A closed loop solar collector system includes a linear concentrating parabolic reflector, a linear vaporizer tube horizontally aligned along the focal line of the parabolic reflector, and a fluid metering assembly attached to the input end of the vaporizer tube for precisely metering a quantity of a vaporizable heat transfer fluid from a supply tank to the vaporizer tube. Solar
Nucleosome Repositioning via Loop Formation
I. M. Kulicand; H. Schiessel
2003-01-01
Active (catalyzed) and passive (intrinsic) nucleosome repositioning is known to be a crucial event during the transcriptional activation of certain eukaryotic genes. Here we consider theoretically the intrinsic mechanism and study in detail the energetics and dynamics of DNA-loop-mediated nucleosome repositioning, as previously proposed by earlier works. The surprising outcome of the present study is the inherent nonlocality of nucleosome
NASA Technical Reports Server (NTRS)
Palkovic, R. A.
1974-01-01
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.
An automatic frequency control loop using overlapping DFTs (Discrete Fourier Transforms)
NASA Technical Reports Server (NTRS)
Aguirre, S.
1988-01-01
An automatic frequency control (AFC) loop is introduced and analyzed in detail. The new scheme is a generalization of the well known Cross Product AFC loop that uses running overlapping discrete Fourier transforms (DFTs) to create a discriminator curve. Linear analysis is included and supported with computer simulations. The algorithm is tested in a low carrier to noise ratio (CNR) dynamic environment, and the probability of loss of lock is estimated via computer simulations. The algorithm discussed is a suboptimum tracking scheme with a larger frequency error variance compared to an optimum strategy, but offers simplicity of implementation and a very low operating threshold CNR. This technique can be applied during the carrier acquisition and re-acquisition process in the Advanced Receiver.
Elucidation of ultrafast photophysics with optical pulse shaping
NASA Astrophysics Data System (ADS)
Grumstrup, Erik Martin
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.
Yönten, Vahap; Akta?, Nahit
2014-01-01
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 18.4 g/L, 0.161 g/L, and 32.4°C, 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 24 h of fermentation time. The obtained results were finally verified with batch reactor experiments carried out under the optimum conditions evaluated. PMID:24117150
Guex, Kenny; Degache, Francis; Gremion, Gérald; Millet, Grégoire P
2013-01-01
The eccentric contraction mode was proposed to be the primary stimulus for optimum angle (angle at which peak torque occurs) shift. However, the training range of motion (or muscle excursion range) could be a stimulus as important. The aim of this study was to assess the influence of the training range of motion stimulus on the hamstring optimum length. It was hypothesised that performing a single set of concentric contractions beyond optimal length (seated at 80° of hip flexion) would lead to an immediate shift of the optimum angle to longer muscle length while performing it below (supine at 0° of hip flexion) would not provide any shift. Eleven male participants were assessed on an isokinetic dynamometer. In both positions, the test consisted of 30 consecutive knee flexions at 4.19 rad · s?¹. The optimum angle was significantly shifted by ?15° in the direction of longer muscle length after the contractions at 80° of hip flexion, while a non-significant shift of 3° was found at 0°. The hamstring fatigability was not influenced by the hip position. It was concluded that the training range of motion seems to be a relevant stimulus for shifting the optimum angle to longer muscle length. Moreover, fatigue appears as a mechanism partly responsible for the observed shift. PMID:23631731
Preliminary estimation of the realistic optimum temperature for vegetation growth in China.
Cui, Yaoping
2013-07-01
The estimation of optimum temperature of vegetation growth is very useful for a wide range of applications such as agriculture and climate change studies. Thermal conditions substantially affect vegetation growth. In this study, the normalized difference vegetation index (NDVI) and daily temperature data set from 1982 to 2006 for China were used to examine optimum temperature of vegetation growth. Based on a simple analysis of ecological amplitude and Shelford's law of tolerance, a scientific framework for calculating the optimum temperature was constructed. The optimum temperature range and referenced optimum temperature (ROT) of terrestrial vegetation were obtained and explored over different eco-geographical regions of China. The results showed that the relationship between NDVI and air temperature was significant over almost all of China, indicating that terrestrial vegetation growth was closely related to thermal conditions. ROTs were different in various regions. The lowest ROT, about 7.0 °C, occurred in the Qinghai-Tibet Plateau, while the highest ROT, more than 22.0 °C, occurred in the middle and lower reaches of the Yangtze River and the Southern China region. PMID:23722421
NASA Astrophysics Data System (ADS)
Javidi, Bahram; Fazlollahi, Amir; Willett, Peter; Réfrégier, Philippe
1995-07-01
The design of an optimum receiver for pattern recognition is based on multiple-alternative hypothesis testing with unknown parameters for detecting and locating a noisy target or a noise-free target in scene noise that is spatially nonoverlapping with this target. The optimum receiver designed for a noise-free target has the interesting property of detecting, without error, a noise-free target that has unknown illumination by using operations that are independent of the scene-noise statistics. We investigate the performance of the optimum receiver designed for nonoverlapping target and scene noise in terms of rotation and scale sensitivity of the input targets and discrimination against similar objects. Because it is not possible in practical systems to have a completely noise-free target, we examine how the performance of the optimum receiver designed for a noise-free target is affected when there is some overlapping noise on the target. The application of the optimum receiver to binary character recognition is described. Computer simulation results are provided.
Kinematical Uniqueness of Loop Quantum Gravity
Fleischhack, Christian
2015-01-01
We review uniqueness results for the kinematical part of loop quantum gravity. After sketching the general loop formalism, the holonomy-flux and the Weyl algebras are introduced. In both cases, then, diffeomorphism invariant representations are described.
Video looping of human cyclic motion
Choi, Hye Mee
2004-09-30
In this thesis, a system called Video Looping is developed to analyze human cyclic motions. Video Looping allows users to extract human cyclic motion from a given video sequence. This system analyzes similarities from a large amount of live footage...
Kinematical Uniqueness of Loop Quantum Gravity
Christian Fleischhack
2015-05-17
We review uniqueness results for the kinematical part of loop quantum gravity. After sketching the general loop formalism, the holonomy-flux and the Weyl algebras are introduced. In both cases, then, diffeomorphism invariant representations are described.
Video looping of human cyclic motion
Choi, Hye Mee
2004-09-30
In this thesis, a system called Video Looping is developed to analyze human cyclic motions. Video Looping allows users to extract human cyclic motion from a given video sequence. This system analyzes similarities from a large amount of live footage...
A Shape Memory Polymer with Improved Shape Recovery
Changdeng Liu; Patrick T. Mather
2005-01-01
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,
Shape Aftereffects Reflect Shape Constancy Operations: Appearance Matters
ERIC Educational Resources Information Center
Storrs, Katherine R.; Arnold, Derek H.
2013-01-01
One of the oldest known visual aftereffects is the shape aftereffect, wherein looking at a particular shape can make subsequent shapes seem distorted in the opposite direction. After viewing a narrow ellipse, for example, a perfect circle can look like a broad ellipse. It is thought that shape aftereffects are determined by the dimensions of…
NASA Astrophysics Data System (ADS)
Forte, Peter; Greenhill, Darrel
1996-09-01
In this paper we define a property applied to contours and 2D shapes we call `shape equivalence', or more strictly, `virtual shape equivalence'. The intuitive idea is that two contours or 2D shapes are `virtually equivalent' (at a given scale of resolution) if they can possibly give rise to identical area sampled images (at the given scale) with respect to a given sampling regime. The word `virtual' is used because the relationship is not a true equivalence relation--in particular it is not strictly transitive. The idea is similar to the psychological notion of `just noticeable difference' (JND). Two stimuli are within a JND threshold if a subject cannot perceptually distinguish them, even though they may in fact be different. Similarly our notion of virtual equivalence of contours corresponds to there being no noticeable difference between them with respect to a certain class of sampling regimes at a particular scale of resolution. The usefulness of the concept is that it can be used to built a formal theory of shape and contour simplification (at various scales) to assist object recognition.
Robust impedance shaping telemanipulation
Colgate, J.E. [Northwestern Univ., Evanston, IL (United States). Dept. of Mechanical Engineering] [Northwestern Univ., Evanston, IL (United States). Dept. of Mechanical Engineering
1993-08-01
When a human operator performs a task via a bilateral manipulator, the feel of the task is embodied in the mechanical impedance of the manipulator. Traditionally, a bilateral manipulator is designed for transparency; i.e., so that the impedance reflected through the manipulator closely approximates that of the task. Impedance shaping bilateral control, introduced here, differs in that it treats the bilateral manipulator as a means of constructively altering the impedance of a task. This concept is particularly valuable if the characteristic dimensions (e.g., force, length, time) of the task impedance are very different from those of the human limb. It is shown that a general form of impedance shaping control consists of a conventional power-scaling bilateral controller augmented with a real-time interactive task simulation (i.e., a virtual environment). An approach to impedance shaping based on kinematic similarity between tasks of different scale is introduced and illustrated with an example. It is shown that an important consideration in impedance shaping controller design is robustness; i.e., guaranteeing the stability of the operator/manipulator/task system. A general condition for the robustness of a bilateral manipulator is derived. This condition is based on the structured singular value ({mu}). An example of robust impedance shaping bilateral control is presented and discussed.
NASA Astrophysics Data System (ADS)
Durak, Nurcan; Nasraoui, Olfa; Schmelz, Joan
2010-07-01
Arch-shaped coronal loops that are isolated from the background are typically acquired manually from massive online image databases to be used in solar coronal research. The manual search for special coronal loops is not only subject to human mistakes but is also time consuming and tedious. In this study, we propose a completely automated image-retrieval system that identifies coronal-loop regions located outside of the solar disk from 17.1 nm EIT images. To achieve this aim, we first apply image-preprocessing techniques to bring out loop structures from their background and to reduce the effect of undesired patterns. Then we extract principal contours from the solar image regions. The geometrical attributes of the extracted principal contours reveal the existence of loops in a given region. Our completely automated decision-making procedure gives promising results in separating the regions with loops from the regions without loops. Based on our loop-detection procedure, we have developed an automated image-retrieval tool that is capable of retrieving images containing loops from a collection of solar images.
Fragmentation of cosmic-string loops
NASA Technical Reports Server (NTRS)
York, Thomas
1989-01-01
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.
Cyclic Shape Invariant Potentials
Sukhatme, U P; Khare, A
1998-01-01
We formulate and study the set of coupled nonlinear differential equations which define a series of shape invariant potentials which repeats after a cycle of $p$ iterations. These cyclic shape invariant potentials enlarge the limited reservoir of known analytically solvable quantum mechanical eigenvalue problems. At large values of $x$, cyclic superpotentials are found to have a linear harmonic oscillator behavior with superposed oscillations consisting of several systematically varying frequencies. At the origin, cyclic superpotentials vanish when the period $p$ is odd, but diverge for $p$ even. The eigenvalue spectrum consists of $p$ infinite sets of equally spaced energy levels, shifted with respect to each other by arbitrary energies spacings $\\omega_k$ can be identified with the periodic points generatedby the logistic map $z_{k+1}=r z_k (1 - z_k)$. Increasing the value of $r$ and following the bifurcation route to chaos corresponds to studying cyclic shape invariant potentials as the period $p$ takes va...
DICKEY,FRED M.; WEICHMAN,LOUIS S.; SHAGAM,RICHARD N.
2000-03-16
Industrial, military, medical, and research and development applications of lasers frequently require a beam with a specified irradiance distribution in some plane. A common requirement is a laser profile that is uniform over some cross-section. Such applications include laser/material processing, laser material interaction studies, fiber injection systems, optical data image processing, lithography, medical applications, and military applications. Laser beam shaping techniques can be divided into three areas: apertured beams, field mappers, and multi-aperture beam integrators. An uncertainty relation exists for laser beam shaping that puts constraints on system design. In this paper the authors review the basics of laser beam shaping and present applications and limitations of various techniques.
NSDL National Science Digital Library
TERC
2010-01-01
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 use—but they can’t 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.
NASA Technical Reports Server (NTRS)
Wieserman, W. R.; Schwarze, G. E.; Niedra, J. M.
1990-01-01
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.
NASA Technical Reports Server (NTRS)
Wieserman, W. R.; Schwarze, G. E.; Niedra, J. M.
1990-01-01
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. [Univ. of Pittsburgh, Johnstown, PA (United States); Schwarze, G.E. [National Aeronautics and Space Administration, Cleveland, OH (United States). Lewis Research Center; Niedra, J.M. [Sverdrup Technology, Inc., Brook Park, OH (United States). Lewis Research Center Group
1994-09-01
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 Metglass 2605SC over the frequency range of 1-50 kHz and temperature range of 23-300 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.
NASA Astrophysics Data System (ADS)
Wieserman, W. R.; Schwarze, G. E.; Niedra, J. M.
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.
Loop Fusion for Data Locality and Parallelism
Sharad Singhai; Kathryn McKinley
1996-01-01
Modern processors use memory hierarchy of several levels. Achieving high performance mandates the effective use of the cache locality. Compiler trans- formations can relieve the programmer from hand- optimizing for the specific machine architectures. Loop fusion is a reordering transformation that merges multiple loops into a single loop. It can in- crease data locality thereby exploiting better cache locality; it
Faulted dislocation loops in quenched aluminium
J. W. Edington; R. E. Smallman
1965-01-01
Dislocation loops containing stacking faults have been observed in quenched aluminium using the electron microscope. It is found that lowering the quenching rate relaxes the stringent purity conditions governing the retention of faulted loops, such that a high proportion of the loops in oil-quenched aluminium (99·97 % purity) contain faults. The results are discussed in terms of the influence of
Rotation scheduling: a loop pipelining algorithm
Liang-Fang Chao; Andrea S. LaPaugh; Edwin Hsing-Mean Sha
1993-01-01
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
Noise analysis of phase-locked loops
Amit Mehrotra
2000-01-01
This work addresses the problem of noise analysis of phase locked loops (PLLs). The problem is formulated as a stochastic differential equation and is solved in presence of circuit white noise sources yielding the spectrum of the PLL output. Specifically, the effect of loop filter characteristics, phase-frequency detector and phase noise of the open loop voltage controlled oscillator (VCO) on
Identify Current in a Magnetic Loop
NSDL National Science Digital Library
Wolfgang Christian
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.
New Identities In Universal Osborn Loops
Temitope Gbolahan Jaiyeola; John Olusola Adeniran
2009-05-13
A question associated with the 2005 open problem of Michael Kinyon (Is every Osborn loop universal?), is answered. Two nice identities that characterize universal (left and right universal) Osborn loops are established. Numerous new identities are established for universal (left and right universal) Osborn loops like CC-loops, VD-loops and universal weak inverse property loops. Particularly, Moufang loops are discovered to obey the new identity $[y(x^{-1}u)\\cdot u^{-1}](xu)=[y(xu)\\cdot u^{-1}](x^{-1}u)$ surprisingly. For the first time, new loop properties that are weaker forms of well known loop properties like inverse property, power associativity and diassociativity are introduced and studied in universal (left and right universal) Osborn loops. Some of them are found to be necessary and sufficient conditions for a universal Osborn to be 3 power associative. For instance, four of them are found to be new necessary and sufficient conditions for a CC-loop to be power associative. A conjugacy closed loop is shown to be diassociative if and only if it is power associative and has a weak form of diassociativity.
Henrique Gomes
2011-08-24
This thesis consists of two parts, connected by one central theme: the dynamics of the "shape of space". The first part of the thesis concerns the construction of a theory of gravity dynamically equivalent to general relativity (GR) in 3+1 form (ADM). What is special about this theory is that it does not possess foliation invariance, as does ADM. It replaces that "symmetry" by another: local conformal invariance. In so doing it more accurately reflects a theory of the "shape of space", giving us reason to call it \\emph{shape dynamics} (SD). In the first part we will try to present some of the highlights of results so far, and indicate what we can and cannot do with shape dynamics. Because this is a young, rapidly moving field, we have necessarily left out some interesting new results which are not yet in print and were developed alongside the writing of the thesis. The second part of the thesis will develop a gauge theory for "shape of space"--theories. To be more precise, if one admits that the physically relevant observables are given by shape, our descriptions of Nature carry a lot of redundancy, namely absolute local size and absolute spatial position. This redundancy is related to the action of the infinite-dimensional conformal and diffeomorphism groups on the geometry of space. We will show that the action of these groups can be put into a language of infinite-dimensional gauge theory, taking place in the configuration space of 3+1 gravity. In this context gauge connections acquire new and interesting meanings, and can be used as "relational tools".
NASA Astrophysics Data System (ADS)
Gomes, Henrique
2011-08-01
This thesis consists of two parts, connected by one central theme: the dynamics of the "shape of space". The first part of the thesis concerns the construction of a theory of gravity dynamically equivalent to general relativity (GR) in 3+1 form (ADM). What is special about this theory is that it does not possess foliation invariance, as does ADM. It replaces that "symmetry" by another: local conformal invariance. In so doing it more accurately reflects a theory of the "shape of space", giving us reason to call it emph{shape dynamics} (SD). In the first part we will try to present some of the highlights of results so far, and indicate what we can and cannot do with shape dynamics. Because this is a young, rapidly moving field, we have necessarily left out some interesting new results which are not yet in print and were developed alongside the writing of the thesis. The second part of the thesis will develop a gauge theory for "shape of space"-theories. To be more precise, if one admits that the physically relevant observables are given by shape, our descriptions of Nature carry a lot of redundancy, namely absolute local size and absolute spatial position. This redundancy is related to the action of the infinite-dimensional conformal and diffeomorphism groups on the geometry of space. We will show that the action of these groups can be put into a language of infinite-dimensional gauge theory, taking place in the configuration space of 3+1 gravity. In this context gauge connections acquire new and interesting meanings, and can be used as "relational tools".
Johansson, Karl Henrik
4/9/2008 1 Closing the Loop over Wireless Networks:Closing the Loop over Wireless Networks Johansson, Pan Gun Park, Emmanuel Witrant Closing the Loop over Wireless Networks:Closing the Loop over Wireless Networks: Fundamentals and Applications Karl H. Johansson Electrical Engineering, Royal Institute
Closed Loop Recycling of PreservativeClosed Loop Recycling of Preservative Treated WoodTreated Wood
Closed Loop Recycling of PreservativeClosed Loop Recycling of Preservative Treated WoodTreated WoodDisposal problem Recycling potentialRecycling potential ValueValue--added productsadded products Closed loop recyclingClosed loop recycling #12;Major Current Disposal OptionsMajor Current Disposal Options Incineration
Morgan, Stephen Eric
1989-01-01
. . Determining ideal friction for v~s~=300in ~ oz. Best friction value is f=ggin ~ oz. . ideal friction versus v~? for t~? ? 5 seconds. Ideal friction versus maximum integral of torque. Open loop control with command angle = 5 and t =5 seconds. Open loop.... is the maximum hub rotation for the i' mode shape, and the remaining elements of q. are the xi's to be used with the Galerkin formulation to determine the physical deformations of the structure for the sx" mode shape. It is important to note that the physical...
Ghoudjehbaklou, H.; Puttgen, H.B.
1988-01-01
This paper outlines an optimum spot price determination procedure in the general context of the Public Utility Regulatory Policies Act, PURPA, provisions. PURPA stipulates that local utilities must offer to purchase all available excess electric energy from Qualifying Facilities, QF, at fair market prices. As a direct consequence of these PURPA regulations, a growing number of owners are installing power producing facilities and optimize their operational schedules to minimize their utility related costs or, in some cases, actually maximize their revenues from energy sales to the local utility. In turn, the utility strives to use spot prices which maximize its revenues from any given Small Power Producing Facility, SPPF, a schedule while respecting the general regulatory and contractual framework. the proposed optimum spot price determination procedure fully models the SPPF operation, it enforces the contractual and regulatory restrictions, and it ensures the uniqueness of the optimum SPPF schedule.
NASA Astrophysics Data System (ADS)
Liu, Dong; Dong, Feng
2008-10-01
Electromagnetic Tomography (EMT) is a non-contacting method for acquiring information of conductivity in physiological area. The interest conductivity range is from 0.1s/m to 2s/m. Electromagnetic Tomography model of sensor is set up in COMSOL and the relation between conductivity and measurement is analyzed and presented. The paper puts forward two evaluating standards for optimum design of sensors involving calculated sensitivity on conductivity and signal /carrier ratio (SCR). Simulation on sensing field reflects the linear relation between conductivity and in-phase or real parts of detective voltages, and simulation on sensors' configuration including sensor location and coils' diameter render the object of sensor optimum design become more valid Simulative data are analyzed elaborately and rationally and finally the author provides the reference range for EMT sensors' configuration. The optimum design of sensor array could acquire significant information of the object field and consequently is beneficial to the further image reconstruction of EMT.
Optimum Number of Display Colors and their Chromaticity Regionsfor LED Traffic Information Board
NASA Astrophysics Data System (ADS)
Nakajima, Santaro; Tsuri, Shinsuke; Nakashima, Yoshio; Takamatsu, Mamoru
Traffic information boards have a vital role in promoting safe and efficient road traffic, by providing the drivers with relevant traffic information on a real-time basis. To achieve good visibility and eye-catching quality, we must know the optimum number of display colors and their chromaticity regions so that the road users can correctly recognize displayed information in a short time. We attempted to determine an optimum number of display colors based on the categorical color (basic perceived color) technique, as well as to define the chromaticity regions for display colors so that a given color is most effectively discriminated from the others. The results showed that the optimum number of display colors is ten, and categorization of the so-defined ten display colors on the chromaticity diagram is extremely useful in designing a traffic information board.
Computer programs for generation and evaluation of near-optimum vertical flight profiles
NASA Technical Reports Server (NTRS)
Sorensen, J. A.; Waters, M. H.; Patmore, L. C.
1983-01-01
Two extensive computer programs were developed. The first, called OPTIM, generates a reference near-optimum vertical profile, and it contains control options so that the effects of various flight constraints on cost performance can be examined. The second, called TRAGEN, is used to simulate an aircraft flying along an optimum or any other vertical reference profile. TRAGEN is used to verify OPTIM's output, examine the effects of uncertainty in the values of parameters (such as prevailing wind) which govern the optimum profile, or compare the cost performance of profiles generated by different techniques. A general description of these programs, the efforts to add special features to them, and sample results of their usage are presented.
On the optimum fields and bounds for heat and mass transport in two turbulent flows
NASA Astrophysics Data System (ADS)
Vitanov, Nikolay
2011-12-01
The optimum theory of turbulence is one of the few tools for obtaining analytical results for transport of heat, mass or momentum by turbulent flows. This is achieved by asymptotic theory which is valid for large values of the characteristic numbers of the investigated fluid system. For small and intermediate values of the Reynolds, Rayleigh or Taylor numbers we have to solve numerically the Euler-Lagrange equations of the corresponding variational problems. Below we discuss numerical results from the application of the Howard-Busse method of the optimum theory of turbulence to two problems: convective heat transport in non-rotating and rotating fluid layer and mass transport in pipe flow. We obtain profiles of the optimum fields and discuss the evolution of the thickness of the boundary layers as well as present our first results about the lower bound on the mass transport in a pipe flow.
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.
NSDL National Science Digital Library
NASA
2012-05-08
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.
NSDL National Science Digital Library
2010-01-01
In this activity, students practice placing big and small shapes into Venn diagrams depending on the rules of the diagram. Students can either specify these rules or have the applet assign the rules so they can try to figure them out by placing shapes in the diagram. This activity allows students to explore Venn diagrams and the terms associated with set theory. This activity includes supplemental materials, including background information about the topics covered, a description of how to use the application, and exploration questions for use with the java applet.
Polymeric triple-shape materials
Bellin, I.; Kelch, S.; Langer, R.; Lendlein, A.
2006-01-01
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