NASA Astrophysics Data System (ADS)
Blanco-Pillado, Jose J.; Olum, Ken D.; Shlaer, Benjamin
2015-09-01
We analyze the shapes of cosmic string loops found in large-scale simulations of an expanding-universe string network. The simulation does not include gravitational backreaction, but we model that process by smoothing the loop using Lorentzian convolution. We find that loops at formation consist of generally straight segments separated by kinks. We do not see cusps or any cusplike structure at the scale of the entire loop, although we do see very small regions of string that move with large Lorentz boosts. However, smoothing of the string almost always introduces two cusps on each loop. The smoothing process does not lead to any significant fragmentation of loops that were in non-self-intersecting trajectories before smoothing.
Optimum shape of a blunt forebody in hypersonic flow
NASA Technical Reports Server (NTRS)
Maestrello, L.; Ting, L.
1989-01-01
The optimum shape of a blunt forebody attached to a symmetric wedge or cone is determined. The length of the forebody, its semi-thickness or base radius, the nose radius and the radius of the fillet joining the forebody to the wedge or cone are specified. The optimum shape is composed of simple curves. Thus experimental models can be built readily to investigate the utilization of aerodynamic heating for boundary layer control. The optimum shape based on the modified Newtonian theory can also serve as the preliminary shape for the numerical solution of the optimum shape using the governing equations for a compressible inviscid or viscous flow.
Optimum pulse shapes for stimulated Raman adiabatic passage
G. S. Vasilev; A. Kuhn; N. V. Vitanov
2009-06-10
Stimulated Raman adiabatic passage (STIRAP), driven with pulses of optimum shape and delay has the potential of reaching fidelities high enough to make it suitable for fault-tolerant quantum information processing. The optimum pulse shapes are obtained upon reduction of STIRAP to effective two-state systems. We use the Dykhne-Davis-Pechukas (DDP) method to minimize nonadiabatic transitions and to maximize the fidelity of STIRAP. This results in a particular relation between the pulse shapes of the two fields driving the Raman process. The DDP-optimized version of STIRAP maintains its robustness against variations in the pulse intensities and durations, the single-photon detuning and possible losses from the intermediate state.
Optimum shape design of rotating shaft by ESO method
Yong-Han Kim; Andy Tan; Bo-Suk Yang; Won-Cheol Kim; Byeong-Keun Choi; Young-Su An
2007-01-01
Evolutionary structural optimization (ESO) method is based on a simple idea that the optimal structure can be produced by\\u000a gradually removing the ineffectively used material from the design domain. ESO seems to have some attractive features in engineering\\u000a aspects: simple and fast. In this paper, ESO is applied to optimize shaft shape for the rotating machinery by introducing\\u000a variable size
Optimum Shape Design Using Automatic Differentiation in Reverse Mode
NASA Technical Reports Server (NTRS)
Hafez, M.; Mohammadi, B.; Pironneau, O.
1996-01-01
This paper shows how to use automatic differentiation in reverse mode as a powerful tool in optimization procedures. It is also shown that for aerodynamic applications the gradients have to be as accurate as possible. In particular, the effect of having the exact gradient of he first or second order spatial discretization schemes is presented. We show that the loss of precision in the gradient affects not only the convergence, but also the final shape. Both two and three dimensional configurations of transonic and supersonic flows have been investigated. These cases involve up to several thousand control parameters.
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.
Linking shape dynamics and loop quantum gravity
NASA Astrophysics Data System (ADS)
Smolin, Lee
2014-08-01
Shape dynamics is a reformulation of general relativity, locally equivalent to Einstein's theory, in which the refoliation invariance of the older theory is traded for local scale invariance. Shape dynamics is here derived in a formulation related to the Ashtekar variables by beginning with a modification of the Plebanski action. The constraints of shape dynamics and their algebra are reproduced in terms of these new variables.
Structured Robust Loop shaping control for HIMAT System Using PSO
NASA Astrophysics Data System (ADS)
Kaitwanidvilai, Somyot; Jangwanitlert, Anuwat; Parnichkun, Manukid
2009-01-01
Robust loop shaping control is a feasible method for designing a robust controller; however, the controller designed by this method is complicated and difficult to implement practically. To overcome this problem, in this paper, a new design technique of a fixed-structure robust loop shaping controller for a highly maneuverable airplane, HIMAT, is proposed. The performance and robust stability conditions of the designed system satisfying H? loop shaping control are formulated as the objective function in the optimization problem. Particle Swarm Optimization (PSO) technique is adopted to solve this problem and to achieve the control parameters of the proposed controller. Simulation results demonstrate that the proposed approach is numerically efficient and leads to performance comparable to that of the other method.
Open-loop shape control for continuous microelectromechanical system
Bifano, Thomas
Open-loop shape control for continuous microelectromechanical system deformable mirror Alioune of a microelectromechanical system deform- able mirror (DM) using an approach that combines sparse calibration algorithm of the microelectromechanical system (MEMS) DM with a continuous facesheet (Fig. 1) is complicated
Quantitative Evaluation of Closed-Loop-Shaped Cardiomyocyte Network by Using Ring-Shaped Electrode
NASA Astrophysics Data System (ADS)
Nomura, Fumimasa; Kaneko, Tomoyuki; Hamada, Tomoyo; Hattori, Akihiro; Yasuda, Kenji
2012-06-01
Re-entry of excitation in the heart is one of the abnormal phenomena that causes lethal arrhythmia and is thought to be induced by the looped structure of the excitation conduction pathway. To evaluate the geometrical pattern dependence of electrophysiological results, we fabricated three models of cardiomyocyte networks and compared their beating frequencies (BFs), amplitudes of a depolarization peak, and field potential durations (FPDs). The set of different closed-loop-shaped network models from 3 to 8 mm in length showed the same BFs, amplitudes, and FPDs independent of their loop lengths, whereas the BFs and FPDs of 60 µm small clusters, and the FPDs of the 2 mm open-line-shaped network model were different from those of a closed-loop-shaped network model. These results indicate that the mm order larger size of clusters might create lower BFs, and the closed-loop-shaped model may generate longer FPDs. They also suggest the importance of spatial arrangement control of the cardoimyocyte community for reproducible measurement of electrophysiological properties of cardiomyocytes, especially control of the closed-loop formation, which might change the waveforms of FPDs depending on the difference in the geometry and conduction pathway of the cell network.
Feedback Control Systems Loop Shaping Design with Practical Considerations
NASA Technical Reports Server (NTRS)
Kopsakis, George
2007-01-01
This paper describes loop shaping control design in feedback control systems, primarily from a practical stand point that considers design specifications. Classical feedback control design theory, for linear systems where the plant transfer function is known, has been around for a long time. But it s still a challenge of how to translate the theory into practical and methodical design techniques that simultaneously satisfy a variety of performance requirements such as transient response, stability, and disturbance attenuation while taking into account the capabilities of the plant and its actuation system. This paper briefly addresses some relevant theory, first in layman s terms, so that it becomes easily understood and then it embarks into a practical and systematic design approach incorporating loop shaping design coupled with lead-lag control compensation design. The emphasis is in generating simple but rather powerful design techniques that will allow even designers with a layman s knowledge in controls to develop effective feedback control designs.
NASA Astrophysics Data System (ADS)
Bhanja, Dipankar; Kundu, Balaram
2012-01-01
A constructal T-shaped fin with temperature dependent thermal conductivity of fin the material exposed to both convective and radiative environments is analyzed by Adomian decomposition method. This method provides a closed form of analytical solution for analyzing the temperature distribution, performance and optimum design. A comparative study has been executed among the present and published works. Unlike the published work, dependent parameters on the performance and optimization analysis are highlighted.
Orientation and shape control of a weight optimum free-free beam in a circular orbit
NASA Technical Reports Server (NTRS)
Bainum, Peter M.; Satyanarayana, K.
1991-01-01
In this study, the vibration and orientation control of large space structures using the linear quadratic regulator technique is investigated. Emphasis is placed on the control of both a class of optimally designed structures and uniform structures meeting the mission requirements using a long free-free beam in orbit as an example. The open loop and closed loop dynamics are compared and the transient responses are obtained to determine the effectiveness of the control system design.
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)
Ramakrishnan, C. V.; Singh, Nidur; Sehgal, D. K.
2007-05-01
In this paper an efficient GA based Three Phase Topology Optimization algorithm which is an improvement over the Two-Phase Method developed by the team at IIT Delhi is presented. The Solid Isotropic Material with Penalization approach is outlined and Sequential Linear Programming method with move limits is utilized for solving the compliance minimization and volume minimization problems with volume and displacement constraints respectively. The need for parametric studies with various penalty factors and initial starting constraints are emphasized. The availability of accurate constraint derivatives with minimal effort is a boon but as in any NLP problem with a large number of variables, the global nature of the optimum is somewhat suspect in SIMP based method. A detailed comparison of the performances of the two phase and three phase methods and the SIMP method is presented for problems of different size and general conclusions are drawn.
Synthesis and optimum luminescence of doughnut-shape undoped and doped CaMoO4.
Lv, Li; Liu, Xiaoqing; Xu, Cong; Wang, Xiaojing
2014-05-01
In this work, we report the size and shape-controlled synthesis of CaMoO4 nanocrystals with an aim of investigate their structural, electronic, and luminescent properties. The samples were carefully characterized by X-ray diffraction, transmission electron microscopy, Fourier transformed infrared spectroscopy, UV-vis diffuse reflectance spectroscopy, and luminescence spectroscopy. It is found that when MoO4(2-) and Ca2+ were mixed at relatively low temperature (in ice salt bath), the reaction produces a uniform population of microparticles with an interesting "doughnut" shapes. Due to the low temperature, the process of crystal nucleus is slow enough to for separated growth. The intensity of the absorption band for CaMoO4 nanocrystals was greatly enhanced with the decrease reaction temperature. The as-prepared CaMoO4 doughnut phosphors reveal a broad emission with a maximum at 500 nm, which exhibit blue-green emission. We also study the luminescent property for Eu(3+)-doped CaMoO4. As for the Eu(3+)-doped samples (initial Ca2+:Eu3+ molar ratio 20:1), it is shown that Eu3+ was substituted at Ca2+ sites in the CaMoO4 host lattice, which favors energy transition between Eu3+ ions and molybdate groups that caused the decrease of strength of the peak in emission spectra. PMID:24734581
Topological Shape Optimum Design of Structures via X-FEM and Level Set Method
NASA Astrophysics Data System (ADS)
Lee, Dong-Kyu; Starossek, Uwe; Shin, Soo-Mi
In this study, a structural topological shape optimization design via the X-FEM and zero level sets is presented. Displacement fields of two-phase topology optimization problems are defined by a weak discontinuity with bisected supports. In order for X-FEM to appropriately be associated with a classical topology optimization algorithm with density design parameters, the design parameters are transformed into control parameters in X-FEM. Then, all elements including enriched elements near material interfaces, which are searched by the control parameters, contain signed distance functions or level set functions at each node. The nodal signed distance functions are bilinearly interpolated, and then, Gauss point signed distance functions determine material properties at Gauss points, i.e. almost complete voids (0.001) or solids (1). Up-wind scheme is used to update the level set functions including zero level set functions, which describe moving material interfaces, followed by shape sensitivity of optimization problems via level set functions. Numerical applications verify the present method produces superior design solutions like smooth material interfaces through considering both mechanically X-FEM and geometrically level set method in comparisons with jagged optimal density distribution results of classical topology optimization.
Precise open-loop control of MEMS deformable mirror shape Thomas Bifano a,c
Bifano, Thomas
Precise open-loop control of MEMS deformable mirror shape Thomas Bifano a,c , Jason Stewart b. The algorithm is based upon an analytical elastic model of the mirror membrane and an empirical error. Keywords: MEMS, adaptive optics, open-loop control, deformable mirror 1. INTRODUCTION In some
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
Messenger RNA fluctuations and regulatory RNAs shape the dynamics of a negative feedback loop
Tlusty, Tsvi
Messenger RNA fluctuations and regulatory RNAs shape the dynamics of a negative feedback loop María may appear damped in the population average. In this paper we investigate the role of RNA stochastic takes into account the RNA stochastic dynamics. We find that messenger RNA random fluctuations can
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 Schoenen1,2 , Gurhan Bulu1,3 , Amir Mirtaheri1 , Halim Yanikomeroglu1 1 Department of Systems and Computer Engineering, Carleton University, Canada 2 Communication Networks (ComNets), Faculty 6, RWTH Aachen University, Germany
3D shape reconstruction of loop objects in X-ray protein crystallography.
Strutz, Tilo
2011-01-01
Knowledge of the shape of crystals can benefit data collection in X-ray crystallography. A preliminary step is the determination of the loop object, i.e., the shape of the loop holding the crystal. Based on the standard set-up of experimental X-ray stations for protein crystallography, the paper reviews a reconstruction method merely requiring 2D object contours and presents a dedicated novel algorithm. Properties of the object surface (e.g., texture) and depth information do not have to be considered. The complexity of the reconstruction task is significantly reduced by slicing the 3D object into parallel 2D cross-sections. The shape of each cross-section is determined using support lines forming polygons. The slicing technique allows the reconstruction of concave surfaces perpendicular to the direction of projection. In spite of the low computational complexity, the reconstruction method is resilient to noisy object projections caused by imperfections in the image-processing system extracting the contours. The algorithm developed here has been successfully applied to the reconstruction of shapes of loop objects in X-ray crystallography. PMID:20714026
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.
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.
Anisotropy and shape of hysteresis loop of frozen suspensions of iron oxide nanoparticles in water
NASA Astrophysics Data System (ADS)
Boekelheide, Zoe; Gruettner, Cordula; Dennis, Cindi
2014-03-01
Colloidal suspensions of nanoparticles in liquids have many uses in biomedical applications. We studied approximately 50 nm diameter iron oxide particles dispersed in H2O for magnetic nanoparticle hyperthermia cancer treatment. Interactions between nanoparticles have been indicated for increasing the heat output under application of an alternating magnetic field, as in hyperthermia. Interactions vary dynamically with an applied field as the nanoparticles reorient and rearrange within the liquid. Therefore, we studied the samples below the liquid freezing point in a range of magnetic field strengths to literally freeze in the effects of interactions. We found that the shape of the magnetic hysteresis loop is squarer (higher anisotropy) when the sample was cooled in a high field, and less square (lower anisotropy) when the sample was cooled in a low or zero field. The cause is most likely the formation of long chains of nanoparticles up to 500 ?m, which we observe optically. This increase in anisotropy may indicate improved heating ability for these nanoparticles under an alternating magnetic field.
NASA Astrophysics Data System (ADS)
Jirsa, M.; P&; Ust, L.; Dlouhý, D.; Koblischka, M. R.
1997-02-01
The scaling and relaxation behavior around the fishtail minimum is studied in detail in a wide temperature range (3-70 K) on DyBa2Cu3O7-? single crystals exhibiting a pronounced fishtail effect. Magnetic hysteresis loops (MHL's) normalized with respect to the height and position of the fishtail maximum fall on a universal curve which form can be derived from the phenomenological model of a thermally activated flux creep proposed by Perkins et al. [Phys. Rev. B 51, 8513 (1995)]. This universal curve tends at low fields towards zero. At low temperatures, the drop of js at low fields is usually masked by a wide central peak. By subtracting the universal curve from the experimental js(B) data we separate the contribution of the central peak. It has a simple, exponentially decaying field dependence. This implies that the fishtail minimum at low fields might be understood as a result of an overlapping of two contributions originating from separate pinning mechanisms: one active mainly at high fields and dying away with B going to zero and another one (responsible for the central peak of the MHL) vanishing rapidly with increasing field. This concept is also supported by relaxation experiments. These experiments confirm that the shape of MHL's is given by a dynamic equilibrium between the induction, pinning, and relaxation processes.
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
Youm, Woosub; Jung, Jongkyu; Lee, Sungq; Park, Kyihwan
2008-01-01
The voice coil motor nanoscanner has the advantages of large working range, easy control, and low cost compared to the conventional lead zirconate titanate driven nanoscanner. However, it has a small damping problem which causes mechanical vibration. The mechanical vibration reduces the accuracy as well as servobandwidth, which deteoriates the atomic force microscopy (AFM) image of the samples. In order to solve the vibration problem, the loop shaping technique [for vertical (z)] and input prefilter [for lateral (xy)] are applied. Experimental results of the proposed techniques are presented for vertical (z) and lateral (xy) scanner. Finally, the AFM images are provided to investigate its effect. PMID:18248039
Audoly, Basile
2012-01-01
PHYSICAL REVIEW E 86, 026119 (2012) Shape of an elastic loop strongly bent by surface tension a simple and reliable way to measure surface tension. DOI: 10.1103/PhysRevE.86.026119 PACS number(s): 89]. For increasing surface tension, it successively bifurcates to a planar oval shape, to a twisted saddlelike
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.
Tethered towing using open-loop input-shaping and discrete thrust levels
NASA Astrophysics Data System (ADS)
Jasper, Lee; Schaub, Hanspeter
2014-12-01
Asteroid retrieval, satellite servicing, and debris removal concepts often rely on a thrusting vehicle to redirect and steer a passive object. One effective way to tow the object is through a tether. This study employs a discretized tether model attached to six degree-of-freedom end bodies. To reduce the risk of a post-burn collision between the end bodies, discrete thrust input shaping profiles are considered including a Posicast input and a bang-off-bang thrust profile. These input shaping techniques attain desirable collision avoidance performance by inducing a tumbling or gravity gradient motion of the tethered formation. Their performance is compared to an earlier frequency notched thruster profile.
Influence of fourfold anisotropy form on hysteresis loop shape in ferromagnetic nanostructures
Ehrmann, Andrea; Blachowicz, Tomasz
2014-08-15
The dependence of the form of different mathematical depictions of fourfold magnetic anisotropies has been examined, using a simple macro-spin model. Strong differences in longitudinal and transverse hysteresis loops occur due to deviations from the usual phenomenological model, such as using absolute value functions. The proposed possible models can help understanding measurements on sophisticated magnetic nanosystems, like exchange bias layered structures employed in magnetic hard disk heads or magnetic nano-particles, and support the development of solutions with specific magnetization reversal behavior needed in novel magneto-electronic devices.
NASA Astrophysics Data System (ADS)
Mather, Amanda L.; Johnson, Richard L.
2014-10-01
Turbidity behavior in streams is a complex and dynamic function of both source material supply and event-driven transport. While the primary controls on turbidity behavior across time and space are still not fully understood, recent increases in the availability of high temporal resolution, colocated stream turbidity, and discharge data provide an opportunity for more detailed analysis. Here we examine methods to quantitatively characterize event responses by modeling the shape of turbidity-discharge hysteresis loops. A total of 1559 events from 20 gages in the Mid-Atlantic region of the U.S. were modeled using both previously reported models and new models combining elements of existing models. The results suggest that a more general power law-based model, utilizing both a discharge rate of change term and a "supply" term, allows characterization of a wide range of simple and complex events. Additionally, this study explores a decorrelation approach to address the strong correlation frequently observed between the power law model coefficient (a) and exponent (b), with the goal of exposing the underlying behavior of each parameter individually. An examination of seasonal parameter behavior suggests that this approach may facilitate greater physically based interpretation of the power law coefficient. The power law parameter decorrelation strategy and the loop models examined here provide a step toward the larger goal of understanding the physical controls on turbidity-discharge hysteretic behavior.
Messenger RNA Fluctuations and Regulatory RNAs Shape the Dynamics of Negative Feedback Loop
Martínez, María Rodríguez; Tlusty, Tsvi; Pilpel, Yitzhak; Furman, Itay; 10.1103/PhysRevE.81.031924
2010-01-01
Single cell experiments of simple regulatory networks can markedly differ from cell population experiments. Such differences arise from stochastic events in individual cells that are averaged out in cell populations. For instance, while individual cells may show sustained oscillations in the concentrations of some proteins, such oscillations may appear damped in the population average. In this paper we investigate the role of RNA stochastic fluctuations as a leading force to produce a sustained excitatory behavior at the single cell level. Opposed to some previous models, we build a fully stochastic model of a negative feedback loop that explicitly takes into account the RNA stochastic dynamics. We find that messenger RNA random fluctuations can be amplified during translation and produce sustained pulses of protein expression. Motivated by the recent appreciation of the importance of non--coding regulatory RNAs in post--transcription regulation, we also consider the possibility that a regulatory RNA transcri...
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 ...
Messenger RNA fluctuations and regulatory RNAs shape the dynamics of a negative feedback loop
NASA Astrophysics Data System (ADS)
Rodríguez Martínez, María; Soriano, Jordi; Tlusty, Tsvi; Pilpel, Yitzhak; Furman, Itay
2010-03-01
Single-cell experiments of simple regulatory networks can markedly differ from cell population experiments. Such differences arise from stochastic events in individual cells that are averaged out in cell populations. For instance, while individual cells may show sustained oscillations in the concentrations of some proteins, such oscillations may appear damped in the population average. In this paper we investigate the role of RNA stochastic fluctuations as a leading force to produce a sustained excitatory behavior at the single-cell level. As opposed to some previous models, we build a fully stochastic model of a negative feedback loop that explicitly takes into account the RNA stochastic dynamics. We find that messenger RNA random fluctuations can be amplified during translation and produce sustained pulses of protein expression. Motivated by the recent appreciation of the importance of noncoding regulatory RNAs in post-transcription regulation, we also consider the possibility that a regulatory RNA transcript could bind to the messenger RNA and repress translation. Our findings show that the regulatory transcript helps reducing gene expression variability both at the single-cell level and at the cell population level.
Optimum design of ninety degree bends
NASA Technical Reports Server (NTRS)
Modi, Vijay; Cabuk, Hayri; Huan, Jian-Chun; Quadracci, Richard
1992-01-01
An algorithm for the optimum design of an internal flow component to obtain the maximum pressure rise is presented. Maximum pressure rise in a duct with simultaneous turning and diffusion is shown to be related to the control of flow separation on the passage walls. Such a flow is usually associated with downstream conditions that are desirable in turbomachinery and propulsion applications to ensure low loss and stable performance. The algorithm requires the solution of an 'adjoint' problem in addition to the 'direct' equations governing the flow in a body, which in the present analysis are assumed to be the laminar Navier-Stokes equations. The theoretical framework and computational algorithms presented in this study are for the steady Navier-Stokes equations. A procedure is developed for the numerical solution of the adjoint equations. This procedure is coupled with a direct solver in a design iteration loop, that provides a new shape with a higher pressure rise. This procedure is first validated for the design of optimum plane diffusers in two-dimensional flow. The direct Navier-Stokes and the 'adjoint' equations are solved using a finite volume formulation for spatial discretization in an artificial compressibility framework. A simplified version of the above approach is then utilized to design ninety degree diffusing bends. Calculations were carried out for a mean radius ratio at inlet of 2.5 and Reynolds numbers varying from 100 to 500. While at this stage laminar flows is assumed, it is shown that a similar approach can be conceived for turbulent flows.
Optimum propeller wind turbines
Sanderson, R.J.; Archer, R.D.
1983-11-01
The Prandtl-Betz-Theodorsen theory of heavily loaded airscrews has been adapted to the design of propeller windmills which are to be optimized for maximum power coefficient. It is shown that the simpler, light-loading, constant-area wake assumption can generate significantly different ''optimum'' performance and geometry, and that it is therefore not appropriate to the design of propeller wind turbines when operating in their normal range of high-tip-speed-to-wind-speed ratio. Design curves for optimum power coefficient are presented and an example of the design of a typical two-blade optimum rotor is given.
Optimum propeller wind turbines
NASA Astrophysics Data System (ADS)
Sanderson, R. J.; Archer, R. D.
1983-12-01
The Prandtl-Betz-Theodorsen theory of heavily loaded airscrews has been adapted to the design of propeller windmills which are to be optimized for maximum power coefficient. It is shown that the simpler, light-loading, constant-area wake assumption can generate significantly different 'optimum' performance and geometry, and that it is therefore not appropriate to the design of propeller wind turbines when operating in their normal range of high-tip-speed-to-wind-speed ratio. Design curves for optimum power coefficient are presented and an example of the design of a typical two-blade optimum rotor is given.
Optimum Wire Shaping of an Interconnect
Friedman, Eby G.
- Electronic Imaging Systems and to the Microelectronics Design Center, and by grants from Xerox Corporation of Electrical and Computer Engineering University of Rochester Rochester, New York 14627-0231 Abstract the New York State Office of Science, Technology & Academic Research to the Center for Advanced Technology
Optimum Cassegrain baffle systems.
Hales, W L
1992-09-01
Formulas are developed for the precise calculation of optimum stray-light baffles for Cassegrain optical systems, including systems having extreme optical curvatures such as those in infrared missile guidance systems. Minimum diffraction and maximum optical efficiency are the primary considerations. PMID:20733716
NASA Astrophysics Data System (ADS)
Vachirasricirikul, Sitthidet; Ngamroo, Issarachai; Kaitwanidvilai, Somyot
It is well known that the power system controller designed by H? control is complicated, high order and impractical. In power system applications, practical structures such as proportional integral derivative (PID) etc., are widely used, because of their simple structure, less number of tuning parameters and low-order. However, tuning of controller parameters to achieve a good performance and robustness is based on designer's experiences. To overcome this problem, this paper proposes a fixed structure robust H? loop shaping control to design Static Var Compensator (SVC) and Automatic Voltage Regulator (AVR) for robust stabilization of voltage fluctuation in an isolated wind-diesel hybrid power system. The structure of the robust controller of SVC and AVR is specified by a PID controller. In the system modeling, a normalized coprime factorization is applied to represent possible unstructured uncertainties in the power system such as variation of system parameters, generating and loading conditions etc. Based on the H? loop shaping, the performance and robust stability conditions are formulated as the optimization problem. The particle swarm optimization is applied to solve for PID control parameters of SVC and AVR simultaneously. Simulation studies confirm the control effect and robustness of the proposed control.
A discrete chromatin loop in the mouse Tcra-Tcrd locus shapes the TCR? and TCR? repertoires.
Chen, Liang; Carico, Zachary; Shih, Han-Yu; Krangel, Michael S
2015-10-01
The locus encoding the T cell antigen receptor (TCR) ?-chain and ?-chain (Tcra-Tcrd) undergoes recombination of its variable-diversity-joining (V(D)J) segments in CD4(-)CD8(-) double-negative thymocytes and CD4(+)CD8(+) double-positive thymocytes to generate diverse TCR? repertoires and TCR? repertoires, respectively. Here we identified a chromatin-interaction network in the Tcra-Tcrd locus in double-negative thymocytes that was formed by interactions between binding elements for the transcription factor CTCF. Disruption of a discrete chromatin loop encompassing the D, J and constant (C) segments of Tcrd allowed a single V segment to frequently contact and rearrange to D and J segments and dominate the adult TCR? repertoire. Disruption of this loop also narrowed the TCR? repertoire, which, we believe, followed as a consequence of the restricted TCR? repertoire. Hence, a single CTCF-mediated chromatin loop directly regulated TCR? diversity and indirectly regulated TCR? diversity. PMID:26258942
Fastenakels, M.; Campana, H.
1984-09-01
For decades, chemical engineers have used various rules of thumb for selecting the size of pipe in continuousprocess plants. Often these methods result in sizes that are not the correct selection for the operating conditions. This causes the plant to be less efficient to operate or more costly to erect. The optimum size is controlled by one of three modes of selection: the least annual cost (energy external source), the pressure drop available or the velocity allowable (often is two-phase flow)./sup 3/ Pressure drop available applies when a pressure loss may be (or must be) absorbed by the pipe. The optimum size then becomes the smallest and the least expensive that permits the flow to take place with no undesirable side effects. Except for very special cases, this would not be used in conjunction with a pumped or compressed fluid. This mode requires at least an approximation of the length of the pipe and the quantity and nature of the fittings in the system before the selection can be made. It can also apply under some conditions to the suction piping for pumps or compressors, to the lines conducting steam to and from reciprocating pumps and to heating equipment.
Schuldberg, David
2015-10-01
Guastello (2015a) opened the call for articles for this issue with Goldberger (1991) and colleagues' findings of chaotic variability in healthy heart rate, noting, 'the principle of healthy variability has extended to other biomedical and psychological phenomena.' He suggests a dialectical underpinning for optimal variability involving 'a combination of the minimum entropy or free energy principle that pushes in a downward direction, and Ashby's Law of Requisite Variety that pushes in an upward direction.' Each of the papers in this issue addresses optimal variability across a variety of health-related areas. The present article surveys these seven papers in relation to five conceptual questions about optimal variability: (a) Is variability a positive or a negative, and how are positive things related to health? (b) How shall we define and measure variability? (c) What constitutes an optimum, and how do we locate one? (d) What is the relationship between optimum variability and health? Finally, it touches on (e) What are underlying principles and phenomena behind healthy variability, and can they inform our vocabulary for health? The paper concludes by discussing practical approaches to dealing with optimization. PMID:26375940
Boyer, M. D.; Andre, R.; Gates, David A.; Gerhardt, S.; Goumiri, I. R.; Menard, Jon
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.
Gao, Feng; Gulay, Suna P.; Kasprzak, Wojciech; Dinman, Jonathan D.
2013-01-01
The Pea Enation Mosaic Virus (PEMV) 3? translational enhancer, known as the kissing-loop T-shaped structure (kl-TSS), binds to 40S subunits, 60S subunits, and 80S ribosomes, whereas the Turnip crinkle virus (TCV) TSS binds only to 60S subunits and 80S ribosomes. Using electrophoretic mobility gel shift assay (EMSA)-based competition assays, the kl-TSS was found to occupy a different site in the ribosome than the P-site-binding TCV TSS, suggesting that these two TSS employ different mechanisms for enhancing translation. The kl-TSS also engages in a stable, long-distance RNA-RNA kissing-loop interaction with a 12-bp 5?-coding-region hairpin that does not alter the structure of the kl-TSS as revealed by molecular dynamics simulations. Addition of the kl-TSS in trans to a luciferase reporter construct containing either wild-type or mutant 5? and 3? PEMV sequences suppressed translation, suggesting that the kl-TSS is required in cis to function, and both ribosome-binding and RNA interaction activities of the kl-TSS contributed to translational inhibition. Addition of the kl-TSS was more detrimental for translation than an adjacent eIF4E-binding 3? translational enhancer known as the PTE, suggesting that the PTE may support the ribosome-binding function of the kl-TSS. Results of in-line RNA structure probing, ribosome filter binding, and high-throughput selective 2?-hydroxyl acylation analyzed by primer extension (hSHAPE) of rRNAs within bound ribosomes suggest that kl-TSS binding to ribosomes and binding to the 5? hairpin are compatible activities. These results suggest a model whereby posttermination ribosomes/ribosomal subunits bind to the kl-TSS and are delivered to the 5? end of the genome via the associated RNA-RNA interaction, which enhances the rate of translation reinitiation. PMID:23986599
Optimum edge detection filter.
Dickey, F M; Shanmugam, K S
1977-01-01
Edge detection and enhancement are required in a number of important image processing applications. In this paper we consider the problem of optimizing spatial frequency domain filters for detecting a class of edges in images. The filter is optimum in that it produces maximum energy in the vicinity of the location of the edge for a given spatial resolution I and the bandwidth ?. We show that the filter transfer function can be specified in terms of the prolate spheroidal wavefunctions for a given space-bandwidth product I?. Further we show that for values of I? less than 2, the optimal filter represents the Laplacian operator in image space followed by a low pass filter with a cutoff frequency ?. PMID:20168442
NASA Astrophysics Data System (ADS)
Cho, Hee Keun
The thesis describes advanced design techniques for composites associated with stress concentrations, buckling and dynamic behaviors. Due to a common presence of geometric discontinuities such as holes and notches and diverse operating environments, the research focuses on optimizing the design of perforated composites to reduce stress concentrations, increase buckling resistance and enhance their dynamic performance when operating in hygrothermal environments. Total Lagrangian nonlinear static, buckling and hygrothermal dynamic FEA formulation procedures for both 3D solid and laminated composite shell elements are newly established and their accuracies verified. Optimum design is achieved here primarily by synergizing finite element analysis (FEA) with a probabilistic evolutionary genetic algorithm (GA). This approach is well suited for enhancing the response of orthotropic and/or laminated composites which involve many design variables. Recognizing ability of the stiffness in the neighborhood of geometric discontinuities to influence composite performance, fiber directions within both individual finite elements and individual plies are optimized locally utilizing an integrated GA-FEA parallel numerical system. Results demonstrates the current approach is superior to more conventional design techniques such as modifying ply thickness or the stacking sequence of individual rectilinear plies.
OPTIMUM PLASMA STATES FOR NEXT STEP TOKAMAKS
LIN-LIU,YR; STAMBAUGH,RD
2002-11-01
OAK A271 OPTIMUM PLASMA STATES FOR NEXT STEP TOKAMAKS. The dependence of the ideal ballooning {beta} limit on aspect ratio, A, and elongation {kappa} is systematically explored for nearly 100% bootstrap current driven tokamak equilibria in a wide range of the shape parameters (A = 1.2-7.0, {kappa} = 1.5-6.0 with triangularity {delta} = 0.5). The critical {beta}{sub N} is shown to be optimal at {kappa} = 3.0-4.0 for all A studied and increases as A decreases with a dependence close to A{sup -0.5}. The results obtained can be used as a theoretical basis for the choice of optimum aspect ratio and elongation of next step burning plasma tokamaks or tokamak reactors.
Optimum strong-motion array geometry for source inversion - II
Iida, M.
1990-01-01
Optimum strong-motion array geometry for source inversions is determined for each of three types of earthquake faults: strike-slip, dip-slip and offshore subduction thrust. It is found that the complete Green's function is capable of stabilizing the accuracy of an inversion solution obtained using theoretical seismograms, regardless of the differences in array configuration. The optimum strong-motion array for a strike-slip fault is characterized by stations well distributed in azimuth, while the optimum array for a dip-slip event has stations arranged in a grid-shaped form. -from Author
Environmentally constrained optimum economic dispatch
R. S. Kumar; K. C. S. Thampathy
1998-01-01
This paper presents a general formulation of the optimum economic load dispatch problem in a system with thermal plants taking into account the constraints on emission of sulfur dioxide and oxides of nitrogen. The proposed algorithm is useful to determine the optimum mix-ratio of high sulfur content and low sulfur content fuels, to limit the sulfur dioxide (SO2) emission per
Performance characteristics of aerodynamically optimum turbines for wind energy generators
NASA Technical Reports Server (NTRS)
Rohrbach, C.; Worobel, R.
1975-01-01
This paper presents a brief discussion of the aerodynamic methodology for wind energy generator turbines, an approach to the design of aerodynamically optimum wind turbines covering a broad range of design parameters, some insight on the effect on performance of nonoptimum blade shapes which may represent lower fabrication costs, the annual wind turbine energy for a family of optimum wind turbines, and areas of needed research. On the basis of the investigation, it is concluded that optimum wind turbines show high performance over a wide range of design velocity ratios; that structural requirements impose constraints on blade geometry; that variable pitch wind turbines provide excellent power regulation and that annual energy output is insensitive to design rpm and solidity of optimum wind turbines.
Su, J. T. [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Science, Beijing 100012 (China); Shen, Y. D.; Liu, Y. [National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, Kunming 650011 (China)
2012-07-20
We present extreme-ultraviolet multi-wavelength observations with the SDO/AIA instruments of quasi-periodic pulsations (QPPs) propagating along a cusp-shaped loop formed after an M2.2 flare on the Sun. Our motivation is to detect whether there were slow-mode magnetoacoustic waves propagating along its protruding flux tube. To this end, with fast Fourier transform we extract the short (<3 minutes) and long (>3 minutes) period components of the QPPs from time-space diagrams of the tube slices. We find that velocity differences did exist among the short/long-period components of different wavelengths, but only one event in the long-period ones showed they were greater than the measurement errors (e.g., 65 km s{sup -1}), which were 330 km s{sup -1} detected in 171 A, 590 km s{sup -1} in 211 A, and 180 km s{sup -1} in 304 A. The intensity modulation in all wavelengths is found to be very large, e.g., {approx}60% of the emission trend for an event in the 171 A passband, which would be an order of magnitude higher than the perturbation of the plasma density in the slow-mode magnetoacoustic waves. Moreover, only the QPPs with upward velocities of 50-300 km s{sup -1} are found in the tube, and the downward ones of several tens of kilometers are never unambiguously detected. Therefore, most of the QPP events under study were likely the episodic outflows along the tube, and the one with a supersonic speed of 590 km s{sup -1} may be a kink wave.
Loop shaping of structural dynamics
Kim, Byeong Hwa
1999-01-01
Dynamic response of a stature can be characterized by mass, stiffness, and damping. Design of a conventional structure is primarily based on stiffness characteristics because damping is assumed to be negligible. Although stiffness-based design...
NASA Astrophysics Data System (ADS)
Belloli, Alberto; Ermanni, Paolo
2007-10-01
The vibration suppression efficiency of so-called shunted piezoelectric systems is decisively influenced by the number, shape, dimensions and position of the piezoelectric ceramic elements integrated into the structure. This paper presents a procedure based on evolutionary algorithms for optimum placement of piezoelectric ceramic modules on highly constrained lightweight structures. The optimization loop includes the CAD software CATIA V5, the FE package ANSYS and DynOPS, a proprietary software tool able to connect the Evolving Object library with any simulation software that can be started in batch mode. A user-defined piezoelectric shell element is integrated into ANSYS 9.0. The generalized electromechanical coupling coefficient is used as the optimization objective. Position, dimensions, orientation, embedding location in the composite lay-up and wiring of customized patches are determined for optimum vibration suppression under consideration of operational and manufacturing constraints, such as added mass, maximum strain and requirements on the control circuit. A rear wing of a racing car is investigated as the test object for complex, highly constrained geometries.
Optimum coal charge crushing level
Filonenko, Yu.Ya.; Sobolev, S.Ya.; Razagonov, V.A.; Muravkov, P.G.; Blokhin, V.S.
1984-01-01
When the optimum minimum coal charge crushing level is attained, an increase in the bulk density and a decrease in crushing costs are achieved. As applied to the conditions of the Novolipetsk Metallurgical Association in particular, a decrease in the extent of charge crushing of 1% facilitates an increase in the bulk density of 0.35-0.52%. The optimum minimum crushing level must be selected from the condition for obtaining coke which most fully meets blast-furnace production requirements. Industrial investigations were carried out at the Novolipetsk Metallurgical Association; an optimum coal charge crushing level (differential crushing scheme) for batteries No. 1-4 and 5-8 was selected on the basis of these investigations.
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 FREQUENCY OF CALIBRATION MONITORING
The paper develops an algorithm by which to compute the optimal frequency of calibration monitoring to minimize the total cost of analyzing a set of samples and the required calibration standards. Optimum calibration monitoring is needed because of the high cost and calibration d...
JOINT PERFORMANCE Guide for Optimum
Organization Code 7. Author(s) 8. Performing Organization Report No. Peter Taylor, Robert Otto Rasmussen, Helga Guide for Optimum JULY 2012 Authors Peter Taylor, National Concrete Pavement Technology Center, Iowa State University Robert Otto Rasmussen, The Transtec Group, Inc. Helga Torres, The Transtec Group, Inc
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.
Solar panel installation configurations for optimum system performance
NASA Astrophysics Data System (ADS)
Jha, A. R.
2010-08-01
The main object of this paper is to identify solar panel installation configurations to achieve optimum system performance irrespective of installation surface configurations. It is important to mention that the panel installation requirements are strictly dependent on the roof configurations, Northern and Southern hemispherical locations, and the latitudes of the installation locations. Panel installation schemes for flat roof, inclined roof, inverted V-shape roof and other roof configurations are briefly discussed. Potential tracking concepts, tracking algorithms, and controllers are identified.
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.
AIAA 2003-3875 OPTIMUM SHAPE DESIGN FOR
Jameson, Antony
- chinery blades and cooling fans operate in unsteady flow and are constantly subjected to unsteady loads- feting, poor gust and acoustic response, and dynamic stall. As yet there have been few efforts
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)
Closed-loop control of intense-laser fragmentation of S{sub 8}
Wells, E.; Betsch, K. J.; Conover, C. W. S.; DeWitt, Merrick J.; Pinkham, D.; Jones, R. R.
2005-12-15
A liquid-crystal-based, laser-pulse shaper has been used in combination with an adaptive genetic feedback algorithm to investigate closed-loop control of intense laser fragmentation of S{sub 8} molecules. We observe that the yield ratios S{sub N}{sup +}:S{sub M}{sup +}, for the production of specific charged fragments S{sub N}{sup +} and S{sub M}{sup +}, can be enhanced by >300% relative to those observed using transform-limited 150-fs laser pulses. We have explored the effectiveness of time- and frequency-domain pulse parametrizations while shaping either (i) only the spectral-phase distribution or (ii) the spectral-phase and amplitude distributions of the light. We find that pulse complexity, requiring control beyond simple manipulation of the peak pulse intensity and duration, is critical for optimizing the yield ratios for most species. The ''optimum'' pulse shapes obtained using different pulse parametrizations show significant differences while yielding similar signal enhancements. In some cases, comparison of the different optimum pulse shapes appears to be a useful method for identifying pulse traits that are, or are not, important for manipulating a particular yield ratio. The importance of specific traits in the optimum pulse shapes is also explored numerically using principal control analysis. We conclude that closed-loop control can be effective for optimizing highly nonlinear strong-field processes. However, in general, intensity variations in a focused laser beam severely limit one's ability to associate the optimization results with specific dynamical mechanisms that bear primary responsibility for the control.
Swarms: Optimum aggregations of spacecraft
NASA Technical Reports Server (NTRS)
Mayer, H. L.
1980-01-01
Swarms are aggregations of spacecraft or elements of a space system which are cooperative in function, but physically isolated or only loosely connected. For some missions the swarm configuration may be optimum compared to a group of completely independent spacecraft or a complex rigidly integrated spacecraft or space platform. General features of swarms are induced by considering an ensemble of 26 swarms, examples ranging from Earth centered swarms for commercial application to swarms for exploring minor planets. A concept for a low altitude swarm as a substitute for a space platform is proposed and a preliminary design studied. The salient design feature is the web of tethers holding the 30 km swarm in a rigid two dimensional array in the orbital plane. A mathematical discussion and tutorial in tether technology and in some aspects of the distribution of services (mass, energy, and information to swarm elements) are included.
Chemical Looping Technology: Oxygen Carrier Characteristics.
Luo, Siwei; Zeng, Liang; Fan, Liang-Shih
2015-07-24
Chemical looping processes are characterized as promising carbonaceous fuel conversion technologies with the advantages of manageable CO2 capture and high energy conversion efficiency. Depending on the chemical looping reaction products generated, chemical looping technologies generally can be grouped into two types: chemical looping full oxidation (CLFO) and chemical looping partial oxidation (CLPO). In CLFO, carbonaceous fuels are fully oxidized to CO2 and H2O, as typically represented by chemical looping combustion with electricity as the primary product. In CLPO, however, carbonaceous fuels are partially oxidized, as typically represented by chemical looping gasification with syngas or hydrogen as the primary product. Both CLFO and CLPO share similar operational features; however, the optimum process configurations and the specific oxygen carriers used between them can vary significantly. Progress in both CLFO and CLPO is reviewed and analyzed with specific focus on oxygen carrier developments that characterize these technologies. PMID:25898071
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.
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.
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.
Aero-optimum hovering kinematics.
Nabawy, Mostafa R A; Crowther, William J
2015-08-01
Hovering flight for flapping wing vehicles requires rapid and relatively complex reciprocating movement of a wing relative to a stationary surrounding fluid. This note develops a compact analytical aero-kinematic model that can be used for optimization of flapping wing kinematics against aerodynamic criteria of effectiveness (maximum lift) and efficiency (minimum power for a given amount of lift). It can also be used to make predictions of required flapping frequency for a given geometry and basic aerodynamic parameters. The kinematic treatment is based on a consolidation of an existing formulation that allows explicit derivation of flapping velocity for complex motions whereas the aerodynamic model is based on existing quasi-steady analysis. The combined aero-kinematic model provides novel explicit analytical expressions for both lift and power of a hovering wing in a compact form that enables exploration of a rich kinematic design space. Good agreement is found between model predictions of flapping frequency and observed results for a number of insects and optimal hovering kinematics identified using the model are consistent with results from studies using higher order computational models. For efficient flight, the flapping angle should vary using a triangular profile in time leading to a constant velocity flapping motion, whereas for maximum effectiveness the shape of variation should be sinusoidal. For both cases the wing pitching motion should be rectangular such that pitch change at stroke reversal is as rapid as possible. PMID:26248884
Scale effect and optimum relations for sea surface planning
NASA Technical Reports Server (NTRS)
Sedov, L.
1947-01-01
From the general dimensional and mechanical similarity theory it follows that a condition of steady motion of a given shape\\bottom with constant speed on the surface of water is determined by four nondimensional parameters. By considering the various systems of independent parameters which are applied in theory and practice and special tests, there is determined their mutual relations and their suitability as planning characteristics. In studying the scale effect on the basis of the Prnndtl formula for the friction coefficient for a turbulent condition the order of magnitude is given of the error in applying the model data to full scale in the case of a single-step bottom For a bottom of complicated shape it is shown how from the test data of the hydrodynamic characteristics for one speed with various loads, or one load with various speeds, there may be obtained by simple computation with good approximation the hydrodynamic characteristics for a different speed or for a different load. (These considerations may be of use in solving certain problems on the stability of planning.) This permits extrapolating the curve of resistance against speed for large speeds inaccessible in the tank tests or for other loads which were not tested. The data obtained by computation are in good agreement with the test results. Problems regarding the optimum trim angle or the optimum width in the case of planning of a flat plate are considered from the point of view of the minimum resistance for a given load on the water and planning speeds. Formulas and graphs are given for the optimum value of the planning coefficient and the corresponding values of the trim angle and width of the flat plate.
Optimum Design of High-Speed Prop-Rotors
NASA Technical Reports Server (NTRS)
Chattopadhyay, Aditi; McCarthy, Thomas Robert
1993-01-01
An integrated multidisciplinary optimization procedure is developed for application to rotary wing aircraft design. The necessary disciplines such as dynamics, aerodynamics, aeroelasticity, and structures are coupled within a closed-loop optimization process. The procedure developed is applied to address two different problems. The first problem considers the optimization of a helicopter rotor blade and the second problem addresses the optimum design of a high-speed tilting proprotor. In the helicopter blade problem, the objective is to reduce the critical vibratory shear forces and moments at the blade root, without degrading rotor aerodynamic performance and aeroelastic stability. In the case of the high-speed proprotor, the goal is to maximize the propulsive efficiency in high-speed cruise without deteriorating the aeroelastic stability in cruise and the aerodynamic performance in hover. The problems studied involve multiple design objectives; therefore, the optimization problems are formulated using multiobjective design procedures. A comprehensive helicopter analysis code is used for the rotary wing aerodynamic, dynamic and aeroelastic stability analyses and an algorithm developed specifically for these purposes is used for the structural analysis. A nonlinear programming technique coupled with an approximate analysis procedure is used to perform the optimization. The optimum blade designs obtained in each case are compared to corresponding reference designs.
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 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.
Runge-Kutta formulas of optimum stability
Sierra, Hector Gonzales
1969-01-01
stability definition (H-Stability), optimum stability will be obtained by fourth-order Runge-Kutta formuj as with parameters, R ? 0, (i = 1, . . . , 4-). 1 Optimum stab i. lity for the second stability defini- tion is given by Runge-Kutta formulas... with oarameters R. ? 0 andb~. -0, (k= 2 . . . 4 In par ticular, a formula due to Runge f ormula satisfying this criteri a wnen 0 & a&, a)( 1 iv ACKNOVLEDGEIIENTS I would like to exyress my sincere appreciation to: Dr. H. A. Luther for his guidance...
Method for Determining Optimum Injector Inlet Geometry
NASA Technical Reports Server (NTRS)
Trinh, Huu P. (Inventor); Myers, W. Neill (Inventor)
2015-01-01
A method for determining the optimum inlet geometry of a liquid rocket engine swirl injector includes obtaining a throttleable level phase value, volume flow rate, chamber pressure, liquid propellant density, inlet injector pressure, desired target spray angle and desired target optimum delta pressure value between an inlet and a chamber for a plurality of engine stages. The method calculates the tangential inlet area for each throttleable stage. The method also uses correlation between the tangential inlet areas and delta pressure values to calculate the spring displacement and variable inlet geometry of a liquid rocket engine swirl injector.
Optimum viewing distance for target acquisition
NASA Astrophysics Data System (ADS)
Holst, Gerald C.
2015-05-01
Human visual system (HVS) "resolution" (a.k.a. visual acuity) varies with illumination level, target characteristics, and target contrast. For signage, computer displays, cell phones, and TVs a viewing distance and display size are selected. Then the number of display pixels is chosen such that each pixel subtends 1 min-1. Resolution of low contrast targets is quite different. It is best described by Barten's contrast sensitivity function. Target acquisition models predict maximum range when the display pixel subtends 3.3 min-1. The optimum viewing distance is nearly independent of magnification. Noise increases the optimum viewing distance.
An optimum balance weight search algorithm
Austrow, J.C. )
1994-07-01
A mathematical description for an optimum balance weight search algorithm for single-plane multipoint balance is presented. The algorithm uses influence coefficients, either measured or known beforehand, and measured complex vibration data to determine an optimum balance correction weight. The solution minimizes the maximum residual vibration. The algorithm allows user-defined balance weights to be analyzed and evaluated. A test case is presented showing actual results and comparison with a least-squares solution algorithm. An efficient multiplane influence coefficient calculation scheme is also presented.
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 structured adsorbents for gas separation processes
Fateme Rezaei; Paul Webley
2009-01-01
Recent developments in separation technology by adsorption have included the development of new structured adsorbents which offer some attractive characteristics compared to a typical packed bed. These improved features include lower energy consumption, higher throughput and superior recovery and purity of product. However, the exact combination of structural, geometric parameters which yields optimum performance is unknown. This study formulates a
Investigation of optimum wavelengths for oximetry
NASA Astrophysics Data System (ADS)
Huong, Audrey K. C.; Stockford, Ian M.; Crowe, John A.; Morgan, Stephen P.
2009-07-01
An evaluation of the optimum choice of wavelengths, when using the 'Modified Lambert-Beer law' to estimate blood oxygen saturation, that minimises the mean error across a range of oxygen saturation values is presented. The stability of this approach and its susceptibility to noise are also considered.
Optimum Output Waveforms in PWM Inverters
Giuseppe S. Buja
1980-01-01
A general method is considered for optimizing the output waveform of pulsewidth-modulated (PWM) inverters, whatever load may be supplied. It consists of the minimization of a cost function of operation of the load fed by the inverter. The mathematical tools and the numerical techniques to calculate the optimum switching patterns in the space of PWM inputs are derived using the
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...
DESIGN GUIDELINES FOR AN OPTIMUM SCRUBBER SYSTEM
The report gives results of a review of the performance and operating experience of existing utility scrubber systems and the state-of-the-art in design of scrubber components. It also gives guidelines for the design of the optimum wet scrubber system, based on this review. The U...
Guinski, Rodrigo 1980-
2012-11-30
, Carol LaFayette Committee Members, Jeff Morris Philip Galanter Head of Department, Tim McLaughlin December 2012 Major Subject: Visualization Copyright 2012 Rodrigo Stromberg Guinski ii ABSTRACT This work consists of a set... ......................................................................................................... 1 ARTISTIC INTENT AND MOTIVATION .................................................................. 3 BACKGROUND .......................................................................................................... 9 Loops...
Formation of loops in DNA under tension
NASA Astrophysics Data System (ADS)
Sankararaman, Sumithra; Marko, John F.
2005-02-01
We study the formation of loops along a DNA molecule under applied tension, as might occur in single-DNA micromanipulation experiments with proteins which are able to simultaneously bind two DNA sites. We consider the case of “bare” DNA in the loop, which forms a “teardrop” shape, and the case where a single DNA-bending protein produces a “kink” in the middle of the loop; the presence of a right-angle kink in the loop reduces its bending energy by a factor of 3. Using the bending energy plus an estimate of the free energies associated with fluctuations and the elasticity of the extended nonlooped DNA, we obtain a probability distribution for loops as a function of loop size and force. Force strongly suppresses formation of all loops, but suppresses large loops more severely than small ones. This quenching effect of force is reduced in the presence of a kink in the loop. We also calculate the speed at which length is absorbed into loops between arbitrary positions along the DNA (i.e., for non-sequence-specific loop forming proteins). The speed of retraction of the molecule decays as a stretched exponential function of the force with characteristic force scales depending on the geometry of the loops.
Shape Representations and Evolution Schemes
Marc Schoenauer
1996-01-01
The choice of a representation i.e. the definitionof the search space, is of vital importancein all Evolutionary Optimization processes. Inthe context of Topological Optimum Design inStructural Mechanics, this paper investigates possiblerepresentations for evolutionary shape design.The goal is the identification of a shape inIRn(n = 2 or n = 3) having optimal mechanicalproperties. Evolutionary Computation has beendemonstrated a valuable tool for
Optimum design and performance of Costas receivers containing soft bandpass limiters
NASA Technical Reports Server (NTRS)
Lindsey, W. C.; Simon, M. K.
1977-01-01
This paper investigates several key questions concerning the mechanization and design of a Costas receiver for reconstruction of a carrier from a suppressed carrier signal. For baseband NRZ encoded data symbols and a soft bandpass limiter preceding the loop, several design issues which are considered herein and which affect acquisition and tracking performance are: (1) The choice of an IF bandwidth. (2) The optimum choice of the Costas arm filter bandwidths as well as the spectral roll-off characteristics. (3) The optimum choice of loop bandwidth to data rate ratio for a given signal-to-noise ratio. (4) The signal suppression factor and the combined limiter-squaring loss. (5) The variations in loop bandwidth and damping with signal level. (6) The choice of the limiter transfer characteristic. (7) Performance degradation due to the presence of a limiter. Various new results in system design are presented and typical numerical results are given and graphically demonstrated in SNR regions of practical interest. The theory is applicable to the design of carrier reconstruction loops required in the implementation of spread spectrum communication receivers.
An approach to optimum subsonic inlet design
NASA Technical Reports Server (NTRS)
Luidens, R. W.; Stockman, N. O.; Diedrich, J. H.
1978-01-01
Inlet operating requirements are compared with estimated inlet separation characteristics to identify the most critical inlet operating condition. This critical condition is taken to be the design point and is defined by the values of inlet mass flow, free-stream velocity and inlet angle of attack. Optimum flow distributions on the inlet surface were determined to be a high, flat top Mach number distribution on the inlet lip to turn the flow quickly into the inlet and a flat bottom skin-friction distribution on the diffuser wall to diffuse the flow rapidly and efficiently to the velocity required at the fan face. These optimum distributions are then modified to achieve other desirable flow characteristics. Example applications are given.
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 bolted joints for hybrid composite materials
Je Hoon Oh; Young Goo Kim; Dai Gil Lee
1997-01-01
The optimum bolted joints for hybrid composite materials composed of glass-epoxy and carbon-epoxy under tensile loading were investigated. The design parameters considered for the bolted joints were ply angle, stacking sequence, the ratio of glass-epoxy to carbon-epoxy, the outer diameters of washers and the clamping pressure. As bearing failure was desirable for bolted joints, the geometry of the bolted joint
Griffith, Jack D.
2013-01-01
In the 1960s, I developed methods for directly visualizing DNA and DNA-protein complexes using an electron microscope. This made it possible to examine the shape of DNA and to visualize proteins as they fold and loop DNA. Early applications included the first visualization of true nucleosomes and linkers and the demonstration that repeating tracts of adenines can cause a curvature in DNA. The binding of DNA repair proteins, including p53 and BRCA2, has been visualized at three- and four-way junctions in DNA. The trombone model of DNA replication was directly verified, and the looping of DNA at telomeres was discovered. PMID:24005675
Griffith, Jack D
2013-10-11
In the 1960s, I developed methods for directly visualizing DNA and DNA-protein complexes using an electron microscope. This made it possible to examine the shape of DNA and to visualize proteins as they fold and loop DNA. Early applications included the first visualization of true nucleosomes and linkers and the demonstration that repeating tracts of adenines can cause a curvature in DNA. The binding of DNA repair proteins, including p53 and BRCA2, has been visualized at three- and four-way junctions in DNA. The trombone model of DNA replication was directly verified, and the looping of DNA at telomeres was discovered. PMID:24005675
Optimum folding pathways of proteins: their determination and properties.
Güner, U?ur; Arkun, Yaman; Erman, Burak
2006-04-01
We develop a dynamic optimization technique for determining optimum folding pathways of proteins starting from different initial configurations. A coarse-grained Go model is used. Forces acting on each bead are (i) the friction force, (ii) forces from bond length constraints, (iii) excluded volume constraints, and (iv) attractive forces between residue pairs that are in contact in the native state. An objective function is defined as the total attractive energy between nonbonded residues, which are neighbors in the native state. The objective function is minimized over all feasible paths, satisfying bond length and excluded volume constraints. The optimization problem is nonconvex and contains a large number of constraints. An augmented Lagrangian method with a penalty barrier function was used to solve the problem. The method is applied to a 36-residue protein, chicken villin headpiece. Sequences of events during folding of the protein are determined for various pathways and analyzed. The relative time scales are compared and scaled according to experimentally measured events. Formation times of the helices, turn, and the loop agree with experimental data. We obtain the overall folding time of the protein in the range of 600 ns-1.2 micros that is smaller than the experimental result of 4-5 micros, showing that the optimal folding times that we obtain may be possible lower bounds. Time dependent variables during folding and energies associated with short- and long-range interactions between secondary structures are analyzed in modal space using Karhunen-Loeve expansion. PMID:16613481
NASA Astrophysics Data System (ADS)
Kontarinis, Dimitrios A.; Howe, Robert D.
1995-12-01
Among the mechanical parameters that are important for dexterous manipulation, shape is useful for both object recognition and control purposes. To investigate the role of shape information in telemanipulation we have created a tactile shape display. This prototype consists of a regular 6 X 4 array of pin elements or `tactors' which rest against the operator's finger tip. Shape memory alloy wires raise individual tactors to approximate the desired surface shape on the skin. We have implemented a feedforward control law and air- cooling that improves the bandwidth of the otherwise slow SMA wires. The hysteretic and nonlinear nature of the SMA actuators has also led us to implement a closed loop controller with position feedback using an optical emitter-receiver pair. The resulting performance of the SMA actuators has a -3 dB bandwidth point between 6 and 7 Hz. We have interfaced the display with a capacitive tactile array sensor and we are able to convey simple shapes from a remote environment through the display. The results of simple tactile feature localization experiments show the ability of the shape relay system to convey shape information.
Sensitivity of optimum solutions to problem parameters
NASA Technical Reports Server (NTRS)
Sobieszczanski-Sobieski, J.; Barthelemy, J. F.; Ryan, K. M.
1981-01-01
Derivation of the sensitivity equations that yield the sensitivity derivatives directly, which avoids the costly and inaccurate perturb-and-reoptimize approach, is discussed and solvability of the equations is examined. The equations apply to optimum solutions obtained by direct search methods as well as those generated by procedures of the sequential unconstrained minimization technique class. Applications are discussed for the use of the sensitivity derivatives in extrapolation of the optimal objective function and design variable values for incremented parameters, optimization with multiple objectives, and decomposition of large optimization problems.
Maintaining an optimum haemocatheter exit site.
Wittich, E
2001-01-01
As a result of crusty growths over some haemocatheter exit sites, it was decided to explore why these crusty scabs occur and how they could be eradicated. It is concluded that a haemocatheter exit site requires a dressing, which will maintain an optimum environment, and avoid contamination from Staphylococcus aureus. Inadine (Johnson & Johnson) a povidine iodine product, applied before the final dressing of Tielle (Johnson & Johnson Medical), a hydropolymer adhesive dressing creates an ideal environment for healing. The haemocatheter exit site can also be inspected at each dialysis session, but can in fact be left insitu for seven days. PMID:11868754
Optimum full-scale subsonic wind tunnel
NASA Technical Reports Server (NTRS)
Mort, K. W.; Soderman, P. T.; Meyn, Larry A.
1986-01-01
The needs and reasons for performing full-scale subsonic research have been studied. Full-scale wind-tunnel requirements are described; recommended size, airspeed, acoustic capabilities, and flow quality are developed; and data-acquisition systems, productivity, automation, and some cost elements are discussed. It is proposed that the optimum full-scale, subsonic wind tunnel be large enough to accommodate aerodynamic and acoustic investigations on most advanced aircraft, which exhibit complex engine/lifting-surface flow-field interactions, including advanced rotorcraft.
Balanced Boolean Functions with Optimum Algebraic Immunity and High Nonlinearity
International Association for Cryptologic Research (IACR)
Balanced Boolean Functions with Optimum Algebraic Immunity and High Nonlinearity Xiangyong Zeng of balanced Boolean functions with optimum algebraic immunity are proposed. The cryptographical properties proposed an infinite class of balanced functions with optimum algebraic immunity as well as a high
Determining the optimum nanofluid for enhanced oil recovery
Determining the optimum nanofluid for enhanced oil recovery Presented by Katie Aurand katherine and size for EOR applications Determining the optimum nanofluid for enhanced oil recovery Presented = particle modification and testing 3 Determining the optimum nanofluid for enhanced oil recovery Presented
Optimum spacing design of grillage systems using a genetic algorithm
M. P. Saka; A. Daloglu; F. Malhas
2000-01-01
In this study a genetic algorithm based method is developed for the optimum design of grillage systems. The algorithm not only selects the optimum sections for the grillage elements from a set of standard universal beam sections, but also finds the optimum spacing required for the grillage system. Deflection limitations and allowable stress constraints are considered in the formulation of
Optimum Size of Nanorods for Heating Application
Seshadri, Gowrishankar; Mehra, Anurag
2013-01-01
Magnetic nanoparticles (MNP's) have become increasingly important in heating applications such as hyperthermia treatment of cancer due to their ability to release heat when a remote external alternating magnetic field is applied. It has been shown that the heating capability of such particles varies significantly with the size of particles used. In this paper, we theoretically evaluate the heating capability of rod-shaped MNP's and identify conditions under which these particles display highest efficiency. For optimally sized monodisperse particles, the power generated by rod-shaped particles is found to be equal to that generated by spherical particles. However, for particles which have a dispersion in size, rod-shaped particles are found to be more effective in heating as a result of the greater spread in the power density distribution curve. Additionally, for rod-shaped particles, a dispersion in the radius of the particle contributes more to the reduction in loss power when compared to a dispersion in the...
Observations of loops and prominences
NASA Technical Reports Server (NTRS)
Strong, Keith T.
1994-01-01
We review recent observations by the Yohkoh-SXT (Soft X-ray Telescope) in collaboration with other spacecraft and ground-based observatories of coronal loops and prominences. These new results point to problems that SoHO will be able to address. With a unique combination of rapid-cadence digital imaging (greater than or equal to 32 s full-disk and greater than or equal to 2 s partial-frame images), high spatial resolution (greater than or equal to 2.5 arcsec pixels), high sensitivity (EM less than or equal to 10(exp 42) cm(exp -3)), a low-scatter mirror, and large dynamic range, SXT can observe a vast range of targets on the Sun. Over the first 21 months of Yohkoh operations SXT has taken over one million images of the corona and so is building up an invaluable long-term database on the large-scale corona and loop geometry. The most striking thing about the SXT images is the range of loop sizes and shapes. The active regions are a bright tangle of magnetic field lines, surrounded by a network of large-scale quiet-Sun loops stretching over distances in excess of 105 km. The cross-section of most loops seems to be constant. Loops displaying significant Gamma's are the exception, not the rule, implying the presence of widespread currents in the corona. All magnetic structures show changes. Time scales range from seconds to months. The question of how these structures are formed, become filled with hot plasma, and are maintained is still open. While we see the propagation of brightenings along the length of active-region loops and in X-ray jets with velocities of several hundred km/s, much higher velocities are seen in the quiet Sun. In XBP flares, for example, velocities of over 1000 km/s are common. Active-region loops seem to be in constant motion, moving slowly outward, carrying plasma with them. During flares, loops often produce localized brightenings at the base and later at the apex of the loop. Quiescent filaments and prominences have been observed regularly. Their coronal manifestation seems to be an extended arcade of loops overlying the filament. Reliable alignment of the ground-based data with the X-ray images make it possible to make a detailed intercomparison of the hot and cold plasma structures over extended periods. Hence we are able to follow the long-term evolution of these structures and see how they become destabilized and erupt.
Optimum interface properties for metal matrix composites
NASA Technical Reports Server (NTRS)
Ghosn, Louis J.; Lerch, Bradley A.
1989-01-01
Due to the thermal expansion coefficient mismatch (CTE) between the fiber and the matrix, high residual sresses exist in metal matrix composite systems upon cool down from processing temperature to room temperature. An interface material can be placed between the fiber and the matrix to reduce the high tensile residual stresses in the matrix. A computer program was written to minimize the residual stress in the matrix subject to the interface material properties. The decision variables are the interface modulus, thickness and thermal expansion coefficient. The properties of the interface material are optimized such that the average distortion energy in the matrix and the interface is minimized. As a result, the only active variable is the thermal expansion coefficient. The optimum modulus of the interface is always the minimum allowable value and the interface thickness is always the maximum allowable value, independent of the fiber/matrix system. The optimum interface thermal expansion coefficient is always between the values of the fiber and the matrix. Using this analysis, a survey of materials was conducted for use as fiber coatings in some specific composite systems.
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.
HNS aluminum linear shaped charge (ALSC) performance study
1980-01-01
A study was performed to determine the HNS conversion process which yields the best material for use in manufacturing aluminum linear shaped charges (ALSC). Destructive testing was performed in two phases. Phase I established optimum standoff for each lot of material, and Phase II evaluated performance under varied temperature conditions. Both optimum standoff and performance were determined by measuring ALSC
Shape of optimal active flagella
Eloy, Christophe
2013-01-01
Many eukaryotic cells use the active waving motion of flexible flagella to self-propel in viscous fluids. However, the criteria governing the selection of particular flagellar waveforms among all possible shapes has proved elusive so far. To address this question, we derive computationally the optimal shape of an internally-forced periodic planar flagellum deforming as a travelling wave. The optimum is here defined as the shape leading to a given swimming speed with minimum energetic cost. To calculate the energetic cost though, we consider the irreversible internal power expanded by the molecular motors forcing the flagellum, only a portion of which ending up dissipated in the fluid. This optimisation approach allows us to derive a family of shapes depending on a single dimensionless number quantifying the relative importance of elastic to viscous effects: the Sperm number. The computed optimal shapes are found to agree with the waveforms observed on spermatozoon of marine organisms, thus suggesting that the...
ERIC Educational Resources Information Center
Jefimenko, Oleg
1974-01-01
Discusses the design of a modified loop-the-loop apparatus in which a water stream is used to illustrate centripetal forces and phenomena of high-velocity hydrodynamics. Included are some procedures of carrying out lecture demonstrations. (CC)
Optimization of the axial power shape in pressurized water reactors
Melik, M. A.
1981-01-01
Analytical and numerical methods have been applied to find the optimum axial power profile in a PWR with respect to uranium utilization. The preferred shape was found to have a large central region of uniform power density, ...
Elevated CO2 and warming effects on CH4 uptake in a semiarid grassland below optimum soil moisture
Technology Transfer Automated Retrieval System (TEKTRAN)
Semiarid rangelands are a significant global sink for methane (CH4), but this sink strength may be altered by climate change. The uptake of CH4 is sensitive to soil moisture showing a hump-shaped relationship with a distinct optimum soil moisture level. Both CO2 and temperature affect soil moistur...
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.
Optimum conditions for microbial carbonate precipitation.
Okwadha, George D O; Li, Jin
2010-11-01
The type of bacteria, bacterial cell concentration, initial urea concentration, reaction temperature, the initial Ca(2+) concentration, ionic strength, and the pH of the media are some factors that control the activity of the urease enzyme, and may have a significant impact on microbial carbonate precipitation (MCP). Factorial experiments were designed based on these factors to determine the optimum conditions that take into consideration economic advantage while at the same time giving quality results. Sporosarcina pasteurii strain ATCC 11859 was used at constant temperature (25°C) and ionic strength with varying amounts of urea, Ca(2+), and bacterial cell concentration. The results indicate that the rate of ureolysis (k(urea)) increases with bacterial cell concentration, and the bacterial cell concentration had a greater influence on k(urea) than initial urea concentration. At 25 mM Ca(2+) concentration, increasing bacterial cell concentration from 10(6) to 10(8)cells mL?¹ increased the CaCO(3) precipitated and CO(2) sequestrated by over 30%. However, when the Ca(2+) concentration was increased 10-fold to 250 mM Ca(2+), the amount of CaCO(3) precipitated and CO(2) sequestrated increased by over 100% irrespective of initial urea concentration. Consequently, the optimum conditions for MCP under our experimental conditions were 666 mM urea and 250 mM Ca(2+) at 2.3×10? cells mL?¹ bacterial cell concentration. However, a greater CaCO(3) deposition is achievable with higher concentrations of urea, Ca(2+), and bacterial cells so long as the respective quantities are within their economic advantage. X-ray Diffraction, Scanning Electron Microscopy and Energy Dispersive X-ray analyzes confirmed that the precipitate formed was CaCO(3) and composed of predominantly calcite crystals with little vaterite crystals. PMID:20947128
Rigged Configurations and Cylindric Loop Schur Functions
Thomas Lam; Pavlo Pylyavskyy; Reiho Sakamoto
2014-10-16
Rigged configurations are known to provide action-angle variables for remarkable discrete dynamical systems known as box-ball systems. We conjecture an explicit piecewise-linear formula to obtain the shapes of a rigged configuration from a tensor product of one-row crystals. We introduce cylindric loop Schur functions and show that they are invariants of the geometric R-matrix. Our piecewise-linear formula is obtained as the tropicalization of ratios of cylindric loop Schur functions. We prove our conjecture for the first shape of a rigged configuration, thus giving a piecewise-linear formula for the lengths of the solitons of a box-ball system.
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 ...
Demonstration of Automatically-Generated Adjoint Code for Use in Aerodynamic Shape Optimization
NASA Technical Reports Server (NTRS)
Green, Lawrence; Carle, Alan; Fagan, Mike
1999-01-01
Gradient-based optimization requires accurate derivatives of the objective function and constraints. These gradients may have previously been obtained by manual differentiation of analysis codes, symbolic manipulators, finite-difference approximations, or existing automatic differentiation (AD) tools such as ADIFOR (Automatic Differentiation in FORTRAN). Each of these methods has certain deficiencies, particularly when applied to complex, coupled analyses with many design variables. Recently, a new AD tool called ADJIFOR (Automatic Adjoint Generation in FORTRAN), based upon ADIFOR, was developed and demonstrated. Whereas ADIFOR implements forward-mode (direct) differentiation throughout an analysis program to obtain exact derivatives via the chain rule of calculus, ADJIFOR implements the reverse-mode counterpart of the chain rule to obtain exact adjoint form derivatives from FORTRAN code. Automatically-generated adjoint versions of the widely-used CFL3D computational fluid dynamics (CFD) code and an algebraic wing grid generation code were obtained with just a few hours processing time using the ADJIFOR tool. The codes were verified for accuracy and were shown to compute the exact gradient of the wing lift-to-drag ratio, with respect to any number of shape parameters, in about the time required for 7 to 20 function evaluations. The codes have now been executed on various computers with typical memory and disk space for problems with up to 129 x 65 x 33 grid points, and for hundreds to thousands of independent variables. These adjoint codes are now used in a gradient-based aerodynamic shape optimization problem for a swept, tapered wing. For each design iteration, the optimization package constructs an approximate, linear optimization problem, based upon the current objective function, constraints, and gradient values. The optimizer subroutines are called within a design loop employing the approximate linear problem until an optimum shape is found, the design loop limit is reached, or no further design improvement is possible due to active design variable bounds and/or constraints. The resulting shape parameters are then used by the grid generation code to define a new wing surface and computational grid. The lift-to-drag ratio and its gradient are computed for the new design by the automatically-generated adjoint codes. Several optimization iterations may be required to find an optimum wing shape. Results from two sample cases will be discussed. The reader should note that this work primarily represents a demonstration of use of automatically- generated adjoint code within an aerodynamic shape optimization. As such, little significance is placed upon the actual optimization results, relative to the method for obtaining the results.
Constricted hysteresis loops in Fe and Ni single crystals
NASA Astrophysics Data System (ADS)
Takahashi, Seiki; Kobayashi, Satoru; Shishido, Toetsu
2010-11-01
Magnetic hysteresis loops reflect the variety of magnetic domain structures and have been considered to have normal rectangular or leaf-like shapes in standard ferromagnets such as Fe and Ni metals. We report on observations of constricted hysteresis loops in Fe and Ni single crystals with very low defect densities. The constricted loops were observed below T=150 K and in a medium temperature range from 150 to 430 K in Fe and Ni single crystals, respectively. These constricted loops disappear by weak plastic deformation for both single crystals. The origin of constricted hysteresis loops was explained by eddy current effects under less domain wall pinning due to dislocations.
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
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.
ERIC Educational Resources Information Center
Bellis, Marilyn
1999-01-01
Explores looping, which involves one teacher staying with the same group of children for more than one year. Recognizes that, with today's changing demographics, looping can be a way to foster a family-like classroom atmosphere. Discusses advantages and disadvantages to looping. Includes a chart of looping opportunities and considerations;…
Optimum production conditions for different high-quality marine algae
Tawfiq S. Abu-Rezq; Lamya Al-Musallam; Jaber Al-Shimmari; Peter Dias
1999-01-01
The possibility of improving the growth rate of different high-quality marine algae was studied. Optimum culture conditions relative to salinities, temperatures and pH levels were defined for three species of Nannochloropsis, Tetraselmis and Isochrysis. In Nannochloropsis, the optimum production ranges were as follows: 20–40‰, 19–21 °C, without using CO2. The optimum conditions for Tetraselmis were: 20–35‰, 19–21 °C, without using
Optimum Algorithms for a Model of Direct Chaining
Vitter, Jeffrey Scott; Chen, Wen-Chin
1985-05-01
algorithms in this class. We give strong evidence in favor of the conjecture hy showing that VICH is optimum under fairly general conditions. Key words, analysis of algorithms, searching, information retrieval, hashing, coalesced hashing, data structures... searches. In some applications, the preferred class of hashing methods is determined by the special nature and requirements of the application. The task is then to find the optimum algorithm within that class. This paper is concerned with optimum algorithms...
Optimum folding pathways for growing protein chains
NASA Astrophysics Data System (ADS)
Senturk, Serife; Baday, Sefer; Arkun, Yaman; Erman, Burak
2007-12-01
The folding of a protein is studied as it grows residue by residue from the N-terminus and enters an environment that stabilizes the folded state. This mode of folding of a growing chain is different from refolding where the full chain folds from a disordered initial configuration to the native state. We propose a sequential dynamic optimization method that computes the evolution of optimum folding pathways as amino acid residues are added to the peptide chain one by one. The dynamic optimization formulation is deterministic and uses Newton's equations of motion and a Go-type potential that establishes the native contacts and excluded volume effects. The method predicts the optimal energy-minimizing path among all the alternative feasible pathways. As two examples, the folding of the chicken villin headpiece, a 36-residue protein, and chymotrypsin inhibitor 2 (CI2), a 64-residue protein, are studied. Results on the villin headpiece show significant differences from the refolding of the same chain studied previously. Results on CI2 mostly agree with the results of refolding experiments and computational work.
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
The optimum bowel preparation for flexible sigmoidoscopy.
Drew, P J; Hughes, M; Hodson, R; Farouk, R; Lee, P W; Wedgwood, K R; Monson, J R; Duthie, G S
1997-08-01
With the proposed introduction of a flexible sigmoidoscopic screening programme for colorectal cancer, patient compliance is of paramount importance. Therefore, the bowel preparation providing optimum cleansing of the bowel with the least associated discomfort and inconvenience for the patient must be found. Patients were randomized to receive either Picolax the evening before the examination or self-administered Fleet enemas prior to the investigation. The endoscopist and nurse practitioner who collected data on a standard questionnaire were blinded to the preparation used. Bowel preparation was graded by the endoscopist as: excellent, good, adequate or poor. One hundred and two consecutive patients were randomized: 56 to the Fleet enema group and 46 to the Picolax group. Self-administered Fleet enemas provided a significantly superior bowel preparation with 52 (93%) being judged adequate or better, as opposed to 34 (74%) in the Picolax group. In addition, Fleet enemas were associated with significantly fewer adverse associated symptoms: 11 (20%) vs 24 (52%). Patients reported to be willing to receive Fleet enemas again in 53 (95%) vs 37 (80%) for the Picolax group. The self-administered Fleet enema is superior to Picolax in terms of bowel preparation for flexible sigmoidoscopy and the incidence of associated adverse symptoms. PMID:9315059
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.
Lorentz self-forces on curved current loops
Garren, D.A.; Chen, J. )
1994-10-01
A derivation is presented for the Lorentz self-force arising from the interaction of a slender current loop of arbitrary shape with its own magnetic field. The self-force on any loop segment depends explicitly on the global shape of the remainder of the loop. Calculations of the self-force are presented for various model loops. For loops having small to moderate noncircularity, it is shown that the self-force on a segment with local major ([ital R]) and minor ([ital a]) radii is approximately that for an axisymmetric torus having uniform [ital R] and [ital a]. These properties of the self-force critically influence the equilibrium and dynamics of thin current loops in solar and astrophysical plasmas.
Ganther, Jr., Kenneth R. (Olathe, KS); Snapp, Lowell D. (Independence, MO)
2002-09-10
A flux locked loop for providing an electrical feedback signal, the flux locked loop employing radio-frequency components and technology to extend the flux modulation frequency and tracking loop bandwidth. The flux locked loop of the present invention has particularly useful application in read-out electronics for DC SQUID magnetic measurement systems, in which case the electrical signal output by the flux locked loop represents an unknown magnetic flux applied to the DC SQUID.
Amit Sever; Pedro Vieira; Tianheng Wang
2011-08-07
We extend the Operator Product Expansion for Null Polygon Wilson loops to the Mason-Skinner-Caron-Huot super loop, dual to non MHV gluon amplitudes. We explain how the known tree level amplitudes can be promoted into an infinite amount of data at any loop order in the OPE picture. As an application, we re-derive all one loop NMHV six gluon amplitudes by promoting their tree level expressions. We also present some new all loops predictions for these amplitudes.
OPTIMUM DUCT DESIGN FOR VARIABLE AIR VOLUME SYSTEMS
OPTIMUM DUCT DESIGN FOR VARIABLE AIR VOLUME SYSTEMS By TAECHEOL KIM Master of Science Oklahoma.2. Problem Definition ................................................................. 36 2.2.1. Initial
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.
NSDL National Science Digital Library
This illustrated guide is designed to help students recognize and learn the different types of leaf shapes. The single Web page, which can be easily printed for use at field sites, shows five leaf shapes.
NASA Technical Reports Server (NTRS)
Busemann, A.; Vinh, N. X.; Culp, R. D.
1974-01-01
The general solution for the optimum three-dimensional aerodynamic control of a lifting vehicle entering a planetary atmosphere is developed. A set of dimensionless variables, modified Chapman variables, is introduced. The resulting exact equations of motion, referred to as Chapman's exact equations, have the advantage that they are completely free of the physical characteristics of the vehicle. Furthermore, a completely general lift-drag relationship is used in the derivation. The results obtained apply to any type of vehicle of arbitrary weight, dimensions and shape, having an arbitrary drag polar, and entering any planetary atmosphere. The aerodynamic controls chosen are the lift coefficient and the bank angle. General optimum control laws for these controls are developed. Several earlier particular solutions are shown to be special cases of this general result. Results are valid for both free and constrained terminal position.
NSDL National Science Digital Library
2012-03-22
In this activity (located on page 9 of PDF), learners compare the stability of a triangle- and square-shaped structure. Learners use straws and paper clips to construct the shapes and then press down on the tops to see which shape collapses. Learners are then encouraged to build stronger shapes, perhaps by using diagonal cross-pieces as triangular bases. Use this activity to introduce compression force and structural stability.
Robert Osada; Thomas A. Funkhouser; Bernard Chazelle; David P. Dobkin
2002-01-01
Measuring the similarity between 3D shapes is a fundamental problem, with applications in computer graphics, computer vision, molecular biology, and a variety of other fields. A challenging aspect of this problem is to find a suitable shape signature that can be constructed and compared quickly, while still discriminating between similar and dissimilar shapes.In this paper, we propose and analyze a
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.
Implementation of optimum solar electricity generating system
NASA Astrophysics Data System (ADS)
Singh, Balbir Singh Mahinder; Sivapalan, Subarna; Najib, Nurul Syafiqah Mohd; Menon, Pradeep; Karim, Samsul Ariffin A.
2014-10-01
Under the 10th Malaysian Plan, the government is expecting the renewable energy to contribute approximately 5.5% to the total electricity generation by the year 2015, which amounts to 98MW. One of the initiatives to ensure that the target is achievable was to establish the Sustainable Energy Development Authority of Malaysia. SEDA is given the authority to administer and manage the implementation of the feed-in tariff (FiT) mechanism which is mandated under the Renewable Energy Act 2011. The move to establish SEDA is commendable and the FiT seems to be attractive but there is a need to create awareness on the implementation of the solar electricity generating system (SEGS). In Malaysia, harnessing technologies related to solar energy resources have great potential for implementation. However, the main issue that plagues the implementation of SEGS is the intermittent nature of this source of energy. The availability of sunlight is during the day time, and there is a need for electrical energy storage system, so that there is electricity available during the night time as well. The meteorological condition such as clouds, haze and pollution affects the SEGS as well. The PV based SEGS is seems to be promising electricity generating system that can contribute towards achieving the 5.5% target and will be able to minimize the negative effects of utilizing fossil fuels for electricity generation on the environment. Malaysia is committed to Kyoto Protocol, which emphasizes on fighting global warming by achieving stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. In this paper, the technical aspects of the implementation of optimum SEGS is discussed, especially pertaining to the positioning of the PV panels.
COMMERCIAL FEASIBILITY OF AN OPTIMUM RESIDENTIAL OIL BURNER HEAD
The report gives results of a study of the feasibility of commercializing optimum oil burner head technology developed earlier for EPA. The study included: selecting the best commercial method for fabricating optimum heads; determining that prototype simulated-production heads co...
Two Optimum Secret Sharing Schemes Revisited Zhengjun Cao Olivier Markowitch
Markowitch, Olivier
Two Optimum Secret Sharing Schemes Revisited Zhengjun Cao Olivier Markowitch Department of Computer, caoamss@gmail.com Abstract In 2006, Obana et al proposed two optimum secret shar- ing schemes secure efficient because they only extend the secret to an array of two elements. The new scheme for a single se
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.
Designing for Optimum Use of Plasma Coatings
NASA Astrophysics Data System (ADS)
Sangam, Mohan; Nikitich, John
1985-09-01
Plasma coatinhs are primarily designed to protect materials from wear, heat corrosion (with sealer), and abrasion. Over the past few years, efforts to develop plasma sprayed coatings have been extensive. Because the properties of coatings vary considerably from those of conventional wrought and cast materials, coatings can be successful only if they are properly chosen, controlled, and tested. This paper shows how the judicious selection of plasma coatings is based on knowledge of coating characteristics, advantages, and limitations and on field experience. Strict control of the powder, the process, and the end product is essential. The best coating results depend on the composition, microstructure, shape, and size distribution of the initial powders. The plasma parameters and spraying techniques also contribute significantly to the quality of the coatings.
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.
Transgressive loop group extensions
Konrad Waldorf
2015-04-27
A central extension of the loop group of a Lie group is called transgressive, if it corresponds under transgression to a degree four class in the cohomology of the classifying space of the Lie group. Transgressive loop group extensions are those that can be explored by finite-dimensional, higher-categorical geometry over the Lie group. We show how transgressive central extensions can be characterized in a loop-group theoretical way, in terms of loop fusion and thin homotopy equivariance.
NSDL National Science Digital Library
Stan Ward
2012-07-31
In this hands-on lesson, students will become Shape Detectives as they identify the two-dimensional shapes, such as triangles, squares and rectangles, needed to build three-dimensional figures including rectangular prisms, square pyramids and cubes. The students will gain an understanding of how two-dimensional shapes are joined together to form three-dimensional figures as well as creating an edible example!
ERIC Educational Resources Information Center
Forsten, Char; Grant, Jim; Richardson, Irv
Looping is an instructional design whereby students progress to the next grade level with the same teacher(s) for two or more years. This book was designed to help teachers and administrators explore, implement, and evaluate looping programs. The book is divided into four parts. Part 1, "Exploring Looping Configurations," identifies the primary…
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.
Optimum fuel injection`s nozzle design and maximum allowable delay to initiate combustion
Laghai, A.; Nabavi, S.H.; Servati, H.B.; Syed, F.
1996-09-01
The problem of fuel economy as well as reducing emissions ideally leads to the complete combustion problem. In the authors` view it has at least 4 complementary dimensions as the following: (1) fuel additives -- to enhance the engine operation and reduce hazardous emissions, this is the field of chemical engineers; (2) IR laser initiated combustion -- by using the heat effects of Laser as well as the infrared absorption, and choosing the frequency of Laser around the resonance of the air-fuel mixture, the authors can initiate a very turbulent fast burning with super high initial temperature, which is a step toward perfect combustion; (3) particle beam -- high energy particles such as UV-laser and hot electron beams can break the unwanted chemical bonds, the research for construction of commercial electron guns is under progress; (4) optimum atomizer and allowable delay time -- this kind of optimization improves combustion too. In this approach, as a sample calculation, the authors choose an optimum pneumatic nozzle design with the shape that follows the optimum size distribution, the Nukiyama-Tanasawa distribution with q = 2. Then using the relation between average size and the nozzle diameters, they determine the diameter of the nozzle as well as air velocity. Nucleation and formation of big droplets have detrimental effects on perfect combustion. In order to minimize the nucleation, the authors determine an upper limit for allowable delay, between injection and initiation of the combustion (by IR Laser).
A comparative approach to closed-loop computation.
Roth, E; Sponberg, S; Cowan, N J
2014-04-01
Neural computation is inescapably closed-loop: the nervous system processes sensory signals to shape motor output, and motor output consequently shapes sensory input. Technological advances have enabled neuroscientists to close, open, and alter feedback loops in a wide range of experimental preparations. The experimental capability of manipulating the topology-that is, how information can flow between subsystems-provides new opportunities to understand the mechanisms and computations underlying behavior. These experiments encompass a spectrum of approaches from fully open-loop, restrained preparations to the fully closed-loop character of free behavior. Control theory and system identification provide a clear computational framework for relating these experimental approaches. We describe recent progress and new directions for translating experiments at one level in this spectrum to predictions at another level. Operating across this spectrum can reveal new understanding of how low-level neural mechanisms relate to high-level function during closed-loop behavior. PMID:24709601
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.
Equilibrium Models of Coronal Loops That Involve Curvature and Buoyancy
NASA Astrophysics Data System (ADS)
Hindman, Bradley W.; Jain, Rekha
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.
THE IMPORTANCE OF GEOMETRIC EFFECTS IN CORONAL LOOP MODELS
Mikic, Zoran; Lionello, Roberto; Linker, Jon A. [Predictive Science, Inc., San Diego, CA 92121 (United States); Mok, Yung [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Winebarger, Amy R. [NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States)
2013-08-20
We systematically investigate the effects of geometrical assumptions in one-dimensional (1D) models of coronal loops. Many investigations of coronal loops have been based on restrictive assumptions, including symmetry in the loop shape and heating profile, and a uniform cross-sectional area. Starting with a solution for a symmetric uniform-area loop with uniform heating, we gradually relax these restrictive assumptions to consider the effects of nonuniform area, nonuniform heating, a nonsymmetric loop shape, and nonsymmetric heating, to show that the character of the solutions can change in important ways. We find that loops with nonuniform cross-sectional area are more likely to experience thermal nonequilibrium, and that they produce significantly enhanced coronal emission, compared with their uniform-area counterparts. We identify a process of incomplete condensation in loops experiencing thermal nonequilibrium during which the coronal parts of loops never fully cool to chromospheric temperatures. These solutions are characterized by persistent siphon flows. Their properties agree with observations (Lionello et al.) and may not suffer from the drawbacks that led Klimchuk et al. to conclude that thermal nonequilibrium is not consistent with observations. We show that our 1D results are qualitatively similar to those seen in a three-dimensional model of an active region. Our results suggest that thermal nonequilibrium may play an important role in the behavior of coronal loops, and that its dismissal by Klimchuk et al., whose model suffered from some of the restrictive assumptions we described, may have been premature.
Piezoactuator Design Considering the Optimum Placement of FGM Piezoelectric Material
Paulino, Glaucio H.
Piezoactuator Design Considering the Optimum Placement of FGM Piezoelectric Material Ronny C has been explored in piezoelectric materials to improve properties and to increase the lifetime of piezoelectric actuators. Elastic, piezoelectric, and dielectric properties are graded along the thickness
50 CFR 648.20 - Maximum optimum yield (OYs).
Code of Federal Regulations, 2010 CFR
2010-10-01
...ADMINISTRATION, DEPARTMENT OF COMMERCE FISHERIES OF THE NORTHEASTERN UNITED STATES Management Measures for the Atlantic Mackerel, Squid, and Butterfish Fisheries § 648.20 Maximum optimum yield (OYs). The OYs specified pursuant to § 648.21...
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.
Paddy stems cutting energy and suggested blade optimum parameters.
Reza, Tabatabaee Koloor
2007-12-15
A pendulum type impact shear test apparatus was designed and constructed to measure the energy required for cutting paddy stem. Experiments were carried out to determine the optimum values of blade bevel angle, oblique angle, tilt angle and blade cutting velocity for cutting paddy stem of Sepidrood variety. The results show that blade bevel angle of 28 degrees, oblique angle of 30 degrees, tilt angle of 35 degrees and blade velocity of 2.24 m sec(-1) are optimum. PMID:19093524
Performance of optimum stacking filters in suppressing uncorrelated noise
R. E. WHITE
1977-01-01
Optimum stacking filters based on estimates of trace signal-to-uncorrelated noise ratios are assessed and compared in performance with conventional straight stacking. It is shown that for the trace durations and signal bandwidths normally encountered in seismic reflection data the errors in estimating signal\\/noise ratios largely counteract the theoretical advantages of the optimum filter. The more specific the filter (e.g. the
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
NSDL National Science Digital Library
2011-08-20
In this activity, learners get a closer look at the shape of a drop of water and a drop of oil. Learners first drip water onto wax paper and examine the shape of separate drops from a side view. Learners then drip oil onto wax paper to examine what shape each drop has and whether oil drops are like water drops or different. Finally learners drip colored water drops and oil drops onto wax paper together, mix oil and water in a container, and observe how the two fluids behave when they are in contact.
Optimum Shape Design for Unsteady Flows with Time-Accurate Continuous and Discrete Adjoint Methods
Jameson, Antony
rotors and turbomachinery blades operate in unsteady flows and are constantly subjected to unsteady loads rotors and turbomachinery and to alleviate the unsteady effects that contribute to flutter, buffeting and turbomachinery blades. The following are a selected number of papers on this topic. Ghayour and Baysal [16
NON-LINEAR FREQUENCY DOMAIN BASED OPTIMUM SHAPE DESIGN FOR UNSTEADY
Jameson, Antony
blades and cooling fans operate in unsteady flow and are constantly subjected to unsteady loads the unsteady effects that contribute to flutter, buffeting, poor gust and acoustic response, and dynamic stall
A method for optimum heating and cooling boiler components of a complex shape
NASA Astrophysics Data System (ADS)
Duda, Piotr; Rz?sa, Dariusz
2015-06-01
A numerical method for determining a transient fluid temperature is presented. The method is formulated to minimizethe total time of heating and cooling operation based on the assumption that maximum tensile and compressivetotal stresses in a solid can not exceed the allowable value during the entire process. The method can be used for any construction element of a simple or complicated geometry. In this method, material properties of solids can be assumed as constant or temperature dependent. The method will be implemented for the heating operationof an outlet header. This construction element is mounted in supercritical power plants. The outlet header is installed in the 460 MW power unit and it is designed for the working pressure of p w = 26.5 MPa and the steam working temperature of T w = 554°C. The results obtained from the proposed method will be compared with the calculations according to TRD 301 - German boiler code
HNS aluminum linear shaped charge (ALSC) performance study
Campos, C.A.
1980-07-01
A study was performed to determine the HNS conversion process which yields the best material for use in manufacturing aluminum linear shaped charges (ALSC). Destructive testing was performed in two phases. Phase I established optimum standoff for each lot of material, and Phase II evaluated performance under varied temperature conditions. Both optimum standoff and performance were determined by measuring ALSC depth of penetration into an aluminum witness plate. Detonation velocity was also measured.
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
This activity gives students practice drawing straight lines with a ruler and looking for and categorizing shapes, for example, by the number of sides in polygons. The Teachers' Notes page includes suggestions for implementation, discussion questions and ideas for extension.
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).
Tyler Helmuth
2014-10-12
Loop-weighted walk with parameter $\\lambda\\geq 0$ is a non-Markovian model of random walks that is related to the loop $O(N)$ model of statistical mechanics. A walk receives weight $\\lambda^{k}$ if it contains $k$ loops; whether this is a reward or punishment for containing loops depends on the value of $\\lambda$. A challenging feature of loop-weighted walk is that it is not purely repulsive, meaning the weight of the future of a walk may either increase or decrease if the past is forgotten. Repulsion is typically an essential property for lace expansion arguments. This article circumvents the lack of repulsion and proves, via the lace expansion, that for any $\\lambda\\geq 0$ loop-weighted walk is diffusive in high dimensions.
Coulomb Explosion Imaging with Shaped Pulses
NASA Astrophysics Data System (ADS)
Wang, Z.; Chen, G. Y.; Minker, G.; Iacangelo, S.; Hill, W. T., III
2008-05-01
Pulse shaping has wide application from coherent control of chemical reactions to quantum computing. We have built a system capable of creating and characterizing optimized pulse shapes with large bandwidths -- > 25 nm. Phase and amplitude shaping are controlled with a liquid crystal spatial light modulator (SLM) while a combination of spectral interferometry techniques -- FROG, SPIDER, and SEA TADPOLE -- are exploited to reconstruct the temporal and spectral phase along with the amplitude of the electric field. Optimized shapes are generated via closed-loop feedback, enabled by a Genetic Algorithm (GA). This poster outlines the application of the GA in combination with Coulomb explosion imaging of small molecular systems.
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!!! ...
Wilson Loops @ 3-Loops in Special Kinematics
Heslop, Paul
2011-01-01
We obtain a compact expression for the octagon MHV amplitude / Wilson loop at 3 loops in planar $\\cN$=4 SYM and in special 2d kinematics in terms of 7 unfixed coefficients. We do this by making use of the cyclic and parity symmetry of the amplitude/Wilson loop and its behaviour in the soft/collinear limits as well as in the leading term in the expansion away from this limit. We also make a natural and quite general assumption about the functional form of the result, namely that it should consist of weight 6 polylogarithms whose symbol consists of basic cross-ratios only (and not functions thereof). We also describe the uplift of this result to 10 points.
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.
A multiobjective shape optimization study for a subsonic submerged inlet
NASA Astrophysics Data System (ADS)
Taskinoglu, Ezgi S.
The purpose of the present work is to summarize the findings of a multiobjective shape optimization study conducted for a subsonic submerged air vehicle inlet. The objective functions of the optimization problem are distortion and swirl indices defined by the distribution of flow parameters over the exit cross-section of the inlet. The geometry alteration is performed by placing a protrusion in the shape of a fin on the baseline inlet surface. Thus, the design variables of the optimization problem are chosen to be the geometrical parameters defining the fin protrusion; namely fin height, length and incidence angle. The Trade Off (also known as epsilon-constraint) method is employed for finding the Pareto optimal set formed by the nondominated solutions of the feasible design space. Since the flow domain solution is required for every step along the line search, an automated optimization loop is constructed by integrating the optimizer with a surface modeler, a mesh generator and a flow solver through which the flow parameters over the compressor face are computed. In addition, the trade study for fin protrusion, the analyses and the comparison of the baseline and Pareto optimal solutions are presented and observations concerning grid resolution and convergence behaviour are discussed. The results display an irregular and discontinuous Pareto optimal set. Optimum inlet designs are scattered in two regions from which one representative inlet design is chosen and analyzed. As a result, it is concluded that an inlet designer has two options within the framework of this optimization study: an inlet design with high swirl but low distortion or an inlet design with low swirl but higher distortion.
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.
Optimum quantum dot size for highly efficient fluorescence bioimaging
NASA Astrophysics Data System (ADS)
Martínez Maestro, Laura; Jacinto, Carlos; Rocha, Uéslen; Carmen Iglesias-de la Cruz, M.; Sanz-Rodriguez, Francisco; Juarranz, Angeles; García Solé, José; Jaque, Daniel
2012-01-01
Semiconductor quantum dots of few nanometers have demonstrated a great potential for bioimaging. The size determines the emitted color, but it is also expected to play an important role in the image brightness. In this work, the size dependence of the fluorescence quantum yield of the highly thermal sensitive CdTe quantum dots has been systematically investigated by thermal lens spectroscopy. It has been found that an optimum quantum yield is reached for 3.8-nm quantum dots. The presence of this optimum size has been corroborated in both one-photon excited fluorescence experiments and two-photon fluorescence microscopy of dot-incubated cancer cells. Combination of quantum yield and fluorescence decay time measurements supports that the existence of this optimum size emerges from the interplay between the frequency-dependent radiative emission rate and the size-dependent coupling strength between bulk excitons and surface trapping states.
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.
Optimum detection for extracting maximum information from symmetric qubit sets
NASA Astrophysics Data System (ADS)
Mizuno, Jun; Fujiwara, Mikio; Akiba, Makoto; Kawanishi, Tetsuya; Barnett, Stephen M.; Sasaki, Masahide
2002-01-01
We demonstrate a class of optimum detection strategies for extracting the maximum information from sets of equiprobable real symmetric qubit states of a single photon. These optimum strategies have been predicted by Sasaki et al. [Phys. Rev. A 59, 3325 (1999)]. The peculiar aspect is that the detections with at least three outputs suffice for optimum extraction of information regardless of the number of signal elements. The cases of ternary (or trine), quinary, and septenary polarization signals are studied where a standard von Neumann detection (a projection onto a binary orthogonal basis) fails to access the maximum information. Our experiments demonstrate that it is possible with present technologies to attain about 96% of the theoretical limit.
NSDL National Science Digital Library
2012-05-09
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.
Fréchet derivative for light-like Wilson Loops
I. Cherednikov; T. Mertens
2014-11-28
We address the equations of motion for the light-like QCD Wilson exponentials defined in the generalized loop space. We attribute an important class of the infinitesimal shape variations of the rectangular light-like Wilson loops to the Fr\\'echet derivative associated to a diffeomorphism in loop space what enables the derivation of the law of the classically conformal-invariant shape variations. We show explicitly that the Fr\\'echet derivative coincides (at least in the leading perturbative or- der) with the area differential operator introduced in the previous works. We discuss interesting implications of this result which will allow one to relate the rapidity evolution and ultra-violet evolution of phenomenologically important quantum correlation functions (such as 3-dimensional parton distribution functions) and geometrical properties of the light-like cusped Wilson loops.
Optimum bandgap of several III-V heterojunction solar cells
NASA Technical Reports Server (NTRS)
Sutherland, J. E.; Hauser, J. R.
1979-01-01
Results of computer analysis of AlAs/Ga(1-x)As n-on-p heterojunction solar cells are presented with particular consideration given to interface recombination effects. It is found that, for an AlAs window layer, GaAs appears to be the optimum semiconductor for the active layer. Furthermore, even if the interface recombination is neglected, GaAs comes so close to being the optimum III-V active layer material that the additional effort required to incorporate a few percent of InAs into the active layer appears to be much greater than any expected efficiency increase.
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.
Chen Integrals, Generalized Loops and Loop Calculus
J. N. Tavares
1993-05-29
We use Chen iterated line integrals to construct a topological algebra ${\\cal A}_p$ of separating functions on the {\\it Group of Loops} ${\\bf L}{\\cal M}_p$. ${\\cal A}_p$ has an Hopf algebra structure which allows the construction of a group structure on its spectrum. We call this topological group, the group of generalized loops $\\widetilde {{\\bf L}{\\cal M}_p}$. Then we develope a {\\it Loop Calculus}, based on the {\\it Endpoint} and {\\it Area Derivative Operators}, providing a rigorous mathematical treatment of early heuristic ideas of Gambini, Trias and also Mandelstam, Makeenko and Migdal. Finally we define a natural action of the "pointed" diffeomorphism group $Diff_p({\\cal M})$ on $ \\widetilde {{\\bf L}{\\cal M}_p}$, and consider a {\\it Variational Derivative} which allows the construction of homotopy invariants. This formalism is useful to construct a mathematical theory of {\\it Loop Representation} of Gauge Theories and Quantum Gravity. Figures available by request.
NASA Astrophysics Data System (ADS)
Schmelz, J. T.
2002-10-01
A controversy over the temperature distribution of coronal loops has arisen recently because different investigators using different techniques have obtained very different answers. Analysis of Solar and Heliospheric Observatory (SOHO) Extreme ultraviolet Imaging Telescope (EIT) and Transition Region and Coronal Explorer (TRACE) data using narrowband ratios to obtain temperature maps has produced several key publications that suggest that coronal loops may be isothermal. On the other hand, our analysis of the SOHO Coronal Diagnostics Spectrometer (CDS) spectral line data taken on 1998 April 20 for several pixels along a relatively isolated coronal loop on the southwest limb of the solar disk is clearly inconsistent with isothermal plasma along either the line of sight or the length of the loop. We have constructed a differential emission measure (DEM) distribution for each pixel; these distributions, taken together, suggested that the DEM-weighted temperature increases from the footpoints to the loop top. We convolved these DEM curves with the three different EIT coronal response functions. This gives us the intensity (in units of DN s-1) of what EIT would ``see'' in the 171, 195, and 284 Å passbands if it were observing the CDS loop. We take a ratio of these values (171 Å/195 Å and 195 Å/284 Å), and use the regular EIT software to calculate a temperature at each pixel for each ratio. EIT ``sees'' a loop with an almost uniform temperature, but the derived temperatures are different for the different ratios. These uniform-temperature loops arise even though the actual temperature input is multithermal both along the line of sight and along the length of the loop. We suspect that these apparent uniform-temperature loops may be an unfortunate by-product of the simplistic filter-ratio method that is used for both EIT and TRACE temperature analysis. Our results indicate that narrow-passband EUV observations must be used in conjunction with other diagnostics to draw quantitative conclusions about the properties of coronal plasma.
ERIC Educational Resources Information Center
Feher, Elsa; Rice, Karen
1986-01-01
Describes an activity in which young children explore the concepts of light by predicting the shape of shadows. Different configurations of light sources are used and objects are held in different positions. Sample questions to be asked of the children before, during, and after the activities are included. (TW)
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.
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.
Channel shape optimization of electromagnetic pumps
Leboucher, L.; Boissonneau, P. [LEGI, Genoble (France). Inst. de Mecanique de Grenoble] [LEGI, Genoble (France). Inst. de Mecanique de Grenoble; Villani, D. [Framatome direction Novatome, Lyon (France)] [Framatome direction Novatome, Lyon (France)
1995-05-01
Electromagnetic pumps are used for the transportation of liquid metals such as the cooling sodium of fast breeder nuclear reactors. The design of this induction machine is close to that of a tubular linear induction motor. In this paper, channels of variable cross section are used to improve the efficiency of electromagnetic pumps. The optimum channel shape is derived analytically and is then tested with a finite element code. The performances are compared with those of standard pumps.
Introduction to Loop Heat Pipes
NASA Technical Reports Server (NTRS)
Ku, Jentung
2015-01-01
This is the presentation file for the short course Introduction to Loop Heat Pipes, to be conducted at the 2015 Thermal Fluids and Analysis Workshop, August 3-7, 2015, Silver Spring, Maryland. This course will discuss operating principles and performance characteristics of a loop heat pipe. Topics include: 1) pressure profiles in the loop; 2) loop operating temperature; 3) operating temperature control; 4) loop startup; 4) loop shutdown; 5) loop transient behaviors; 6) sizing of loop components and determination of fluid inventory; 7) analytical modeling; 8) examples of flight applications; and 9) recent LHP developments.
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…
Optimum Camera Angle for Optic Flow-Based Centering Response
Sukhatme, Gaurav S.
] [7] [8]. This centering response allows a UAV to fly down the center of an urban canyon for example with a simulated autonomous helicopter in a 3D urban canyon. In this context, we define the optimum camera angle of an autonomous helicopter through urban environments [10], and our investigation therefore incor- porates
Optimum Image Compression Techniques with Data Transform Pyramid
Muhammad Kamran; Shi Feng; Nasir Rahman; Suhail Aftab Qureshi
2006-01-01
Digital circuits are designed and implemented with respect to time and area optimization. Particularly in the field of image processing, data is to be transmitted from source to destination with optimum conditions of quality and transmitting speed. These objectives are achieved in diverse schemes under different circumstances. This paper describes a method to deal with image compression techniques to explain
Optimum Symmetry breaking in CSPs using Group Theory
Rossi, Francesca
Optimum Symmetry breaking in CSPs using Group Theory Iain McDonald ? University of St Andrews, Fife, Scotland, iain@dcs.st-and.ac.uk Abstract. In this abstract I describe new methods of symmetry break- ing that will optimise the way in which symmetries are broken during search. I also present a new multi
The optimum conditions for structures of work hardening elastoplastic materials
Selyugin, S.V. [Tsent Aerogidrodinam. Inst., Zhukovskii (Russian Federation)
1995-12-01
Problems of optimization of truss, beam, and membrane type structures of work hardening elastoplastic materials in static loading are studied. The optimum conditions are obtained and analyzed on the basis of variation principles. It is shown that these conditions determine the equal strength of structures.
An Application of Calculus: Optimum Parabolic Path Problem
ERIC Educational Resources Information Center
Atasever, Merve; Pakdemirli, Mehmet; Yurtsever, Hasan Ali
2009-01-01
A practical and technological application of calculus problem is posed to motivate freshman students or junior high school students. A variable coefficient of friction is used in modelling air friction. The case in which the coefficient of friction is a decreasing function of altitude is considered. The optimum parabolic path for a flying object…
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
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.
Ch. 3 Huffman Coding Two Requirements for Optimum Prefix Codes
Fowler, Mark
in the last bit These three requirements lead to a simple way of building a binary tree describing an optimum by the two smallest probabilities into a parent node 3. Label the parent node w/ the sum of the two children's probabilities · This parent node is now considered to be a "super symbol" (it replaces its two children symbols
Optimum Buffer Size for Dynamic Voltage Ali Manzak1
Kambhampati, Subbarao
on the task load. The DC/DC converter has a sensitivity of V and can provide voltages in the range VminOptimum Buffer Size for Dynamic Voltage Processors Ali Manzak1 and Chaitali Chakrabarti2 1 Suleyman size for a dynamic voltage scaling processor. We determine the minimum required buffer size giving
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
Integrating System Optimum and User Equilibrium in Traffic Assignment via
Yeoh, William
be thought of as one that describes the network at its best operation, in which congestion is minimized when to manage the traffic in order to achieve an optimum social equilibrium. However, it also has applications in the operations of a network: while in a real, congested, urban traffic system the flows observed are more likely
Optimum Combining for Indoor Radio Systems with Multiple Users
J. Winters
1987-01-01
This paper studies the use of optimum combining to increase the capacity of narrow-band in-building radio communication systems with multiple users. We consider systems consisting of a base Station with numerous remotes in a Rayleigh fading environment and study the problem of more users requiring channels than the number of channels available. A system is described that, with multiple antennas
Carbon Nanotube Bundle Interconnect: Performance Evaluation, Optimum Repeater Size and
Ayers, Joseph
]. Table I shows resistivity for the copper wire for different technology nodes [3] [20]. Carbon nanotubeCarbon Nanotube Bundle Interconnect: Performance Evaluation, Optimum Repeater Size and Insertion on carbon nanotube (CNT) interconnect bundle model. For the greater length of the wire, a methodology
Automatic planning concept - An analysis of optimum scheduling
NASA Technical Reports Server (NTRS)
Rebelein, P. R.; Truenbels, P.
1968-01-01
Study considers resource costs, mission constraints, and experiment results as linear functions, insofar as possible, in an effort to develop optimum scheduling by the use of linear programming. It involves a mathematical approach in which a number of constraints are considered operative.
Two universal results for Wilson loops at strong coupling
Hartnoll, Sean A. [DAMTP, Centre for Mathematical Sciences, Cambridge University, Wilberforce Road, Cambridge CB3 OWA (United Kingdom)
2006-09-15
We present results for Wilson loops in strongly coupled gauge theories. The loops may be taken around an arbitrarily shaped contour and in any field theory with a dual IIB geometry of the form MxS{sup 5}. No assumptions about supersymmetry are made. The first result uses D5 branes to show how the loop in any antisymmetric representation is computed in terms of the loop in the fundamental representation. The second result uses D3 branes to observe that each loop defines a rich sequence of operators associated with minimal surfaces in S{sup 5}. The action of these configurations are all computable. Both results have features suggesting a connection with integrability.
Research on the optimum length-diameter ratio of the charge of a multimode warhead
NASA Astrophysics Data System (ADS)
Li, Weibing; Wang, X.; Li, Wenbin; Zheng, Y.
2012-05-01
This paper outlines our research on a multimode warhead in which we adopted center point and annular initiation modes to form multimode penetrators. Using LS-DYNA software, we studied the effect of the configuration parameters, namely the length/diameter ratio of the shaped charge, on the formation parameters, such as the velocity and length/diameter ratio, of multimode penetrators. We found that when the charge length was in the range of 0.9-1.2 times the charge diameter, the same structure of shaped charge can form suitable multimode penetrators. Either an explosively formed penetrator (EFP) or a long stretchy rod-shaped EFP penetrator can be formed. We establish an optimum charge length for penetrator formation of 1.4 times the charge diameter. Simulation results were validated using X-ray imaging experiments and they were in good agreement. The results found that by increasing the charge length from 0.9 to 1.4 times the charge diameter, the penetration depth of the EFP increased by 74.5%, while increasing the charge length from 1.4 to 1.6 times the charge diameter only increased the penetration depth by 1.9%.
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.
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.
NASA Astrophysics Data System (ADS)
Vilar, Jose M. G.; Saiz, Leonor
2006-06-01
DNA looping plays a fundamental role in a wide variety of biological processes, providing the backbone for long range interactions on DNA. Here we develop the first model for DNA looping by an arbitrarily large number of proteins and solve it analytically in the case of identical binding. We uncover a switchlike transition between looped and unlooped phases and identify the key parameters that control this transition. Our results establish the basis for the quantitative understanding of fundamental cellular processes like DNA recombination, gene silencing, and telomere maintenance.
More supersymmetric Wilson loops
Nadav Drukker; Simone Giombi; Riccardo Ricci; Diego Trancanelli
2007-04-18
We present a large new family of Wilson loop operators in N=4 supersymmetric Yang-Mills theory. For an arbitrary curve on the three dimensional sphere one can add certain scalar couplings to the Wilson loop so it preserves at least two supercharges. Some previously known loops, notably the 1/2 BPS circle, belong to this class, but we point out many more special cases which were not known before and could provide further tests of the AdS/CFT correspondence.
Optimum primary and supplementary signals optimizing the seismic data resolution
NASA Astrophysics Data System (ADS)
Tyapkin, Yuriy K.
2001-03-01
Often in practice, when generating seismic waves on a line, even with a wide-band source, numerous natural and technical obstacles cause a low resolution of reflection seismograms. In this case, the economy of the survey should be taken into consideration and rather than ignoring preexisting data, generating additional signal to complement the preexisting data should be tried. This paper describes how this can be done to optimize the resolution of the combined data. The new approach requires a fundamental change in the field technique such that records with different spectral characteristics (RDSC) are now generated from each source-receiver pair. These coincident records share a common reflectivity series, but differ from each other in wavelets and noise. A comprehensive theory for optimum processing (deconvolution) of any available suite of the RDSC is developed. The solution for the problem is a particular case of multichannel Wiener filtering. It can be thought of as two successive procedures. The first is optimum frequency-dependent weighted stacking of the RDSC. The second is single-channel zero-phase Wiener deconvolution filtering of the previous output. This representation enables suggested multichannel filtering to be easily implemented. The effectiveness of the method as well as its advantage over straight summing of the RDSC, followed by single-channel Wiener deconvolution filtering, are corroborated theoretically and demonstrated with field data. Furthermore, a solution is suggested for the problem to evaluate the spectrum of an optimum supplementary signal. The signal contributes to the available set of the RDSC and yields either maximum resolution with limited energy expenses or a certain desired resolution with minimum, but unrestricted energy expenses at the output of the optimum procedure. The optimum distribution of the spectral energy of a primary signal along the frequency axis is a particular case of the above problem with no preexisting data.
Riverbed: a novel user-steered image segmentation method based on optimum boundary tracking.
Miranda, Paulo A V; Falcão, Alexandre Xavier; Spina, Thiago V
2012-06-01
This paper presents an optimum user-steered boundary tracking approach for image segmentation, which simulates the behavior of water flowing through a riverbed. The riverbed approach was devised using the image foresting transform with a never-exploited connectivity function. We analyze its properties in the derived image graphs and discuss its theoretical relation with other popular methods such as live wire and graph cuts. Several experiments show that riverbed can significantly reduce the number of user interactions (anchor points), as compared to live wire for objects with complex shapes. This paper also includes a discussion about how to combine different methods in order to take advantage of their complementary strengths. PMID:22345539
Realizable feed-element patterns and optimum aperture efficiency in multibeam antenna systems
NASA Technical Reports Server (NTRS)
Yngvesson, K. S.; Rahmat-Samii, Y.; Johansson, J. F.; Kim, Y. S.
1988-01-01
The results of an earlier paper by Rahmat-Samii et al. (1981), regarding realizable patterns from feed elements that are part of an array that feeds a reflector antenna, are extended. The earlier paper used a cos exp q theta model for the element radiation pattern, whereas here a parametric study is performed, using a model that assumes a central beam of cos exp q theta shape, with a constant sidelobe level outside the central beam. Realizable q-values are constrained by the maximum directivity based on feed element area. The optimum aperture efficiency (excluding array feed network losses) in an array-reflector system is evaluated as a function of element spacing using this model as well as the model of the earlier paper. Experimental data for tapered slot antenna (TSA) arrays are in agreement with the conclusions based on the model.
Natively Unstructured Loops Differ from Other Loops
Schlessinger, Avner; Liu, Jinfeng; Rost, Burkhard
2007-01-01
Natively unstructured or disordered protein regions may increase the functional complexity of an organism; they are particularly abundant in eukaryotes and often evade structure determination. Many computational methods predict unstructured regions by training on outliers in otherwise well-ordered structures. Here, we introduce an approach that uses a neural network in a very different and novel way. We hypothesize that very long contiguous segments with nonregular secondary structure (NORS regions) differ significantly from regular, well-structured loops, and that a method detecting such features could predict natively unstructured regions. Training our new method, NORSnet, on predicted information rather than on experimental data yielded three major advantages: it removed the overlap between testing and training, it systematically covered entire proteomes, and it explicitly focused on one particular aspect of unstructured regions with a simple structural interpretation, namely that they are loops. Our hypothesis was correct: well-structured and unstructured loops differ so substantially that NORSnet succeeded in their distinction. Benchmarks on previously used and new experimental data of unstructured regions revealed that NORSnet performed very well. Although it was not the best single prediction method, NORSnet was sufficiently accurate to flag unstructured regions in proteins that were previously not annotated. In one application, NORSnet revealed previously undetected unstructured regions in putative targets for structural genomics and may thereby contribute to increasing structural coverage of large eukaryotic families. NORSnet found unstructured regions more often in domain boundaries than expected at random. In another application, we estimated that 50%–70% of all worm proteins observed to have more than seven protein–protein interaction partners have unstructured regions. The comparative analysis between NORSnet and DISOPRED2 suggested that long unstructured loops are a major part of unstructured regions in molecular networks. PMID:17658943
de Oliveira, Leandro C.; da Silva, Viviam M.; Colussi, Francieli; Cabral, Aline D.; de Oliveira Neto, Mario; Squina, Fabio M.; Garcia, Wanius
2015-01-01
Endo-?-1, 4-mannanase from Thermotoga petrophila (TpMan) is a modular hyperthermostable enzyme involved in the degradation of mannan-containing polysaccharides. The degradation of these polysaccharides represents a key step for several industrial applications. Here, as part of a continuing investigation of TpMan, the region corresponding to the GH5 domain (TpManGH5) was characterized as a function of pH and temperature. The results indicated that the enzymatic activity of the TpManGH5 is pH-dependent, with its optimum activity occurring at pH 6. At pH 8, the studies demonstrated that TpManGH5 is a molecule with a nearly spherical tightly packed core displaying negligible flexibility in solution, and with size and shape very similar to crystal structure. However, TpManGH5 experiences an increase in radius of gyration in acidic conditions suggesting expansion of the molecule. Furthermore, at acidic pH values, TpManGH5 showed a less globular shape, probably due to a loop region slightly more expanded and flexible in solution (residues Y88 to A105). In addition, molecular dynamics simulations indicated that conformational changes caused by pH variation did not change the core of the TpManGH5, which means that only the above mentioned loop region presents high degree of fluctuations. The results also suggested that conformational changes of the loop region may facilitate polysaccharide and enzyme interaction. Finally, at pH 6 the results indicated that TpManGH5 is slightly more flexible at 65°C when compared to the same enzyme at 20°C. The biophysical characterization presented here is well correlated with the enzymatic activity and provide new insight into the structural basis for the temperature and pH-dependent activity of the TpManGH5. Also, the data suggest a loop region that provides a starting point for a rational design of biotechnological desired features. PMID:25723179
de Oliveira, Leandro C; da Silva, Viviam M; Colussi, Francieli; Cabral, Aline D; de Oliveira Neto, Mario; Squina, Fabio M; Garcia, Wanius
2015-01-01
Endo-?-1, 4-mannanase from Thermotoga petrophila (TpMan) is a modular hyperthermostable enzyme involved in the degradation of mannan-containing polysaccharides. The degradation of these polysaccharides represents a key step for several industrial applications. Here, as part of a continuing investigation of TpMan, the region corresponding to the GH5 domain (TpManGH5) was characterized as a function of pH and temperature. The results indicated that the enzymatic activity of the TpManGH5 is pH-dependent, with its optimum activity occurring at pH 6. At pH 8, the studies demonstrated that TpManGH5 is a molecule with a nearly spherical tightly packed core displaying negligible flexibility in solution, and with size and shape very similar to crystal structure. However, TpManGH5 experiences an increase in radius of gyration in acidic conditions suggesting expansion of the molecule. Furthermore, at acidic pH values, TpManGH5 showed a less globular shape, probably due to a loop region slightly more expanded and flexible in solution (residues Y88 to A105). In addition, molecular dynamics simulations indicated that conformational changes caused by pH variation did not change the core of the TpManGH5, which means that only the above mentioned loop region presents high degree of fluctuations. The results also suggested that conformational changes of the loop region may facilitate polysaccharide and enzyme interaction. Finally, at pH 6 the results indicated that TpManGH5 is slightly more flexible at 65°C when compared to the same enzyme at 20°C. The biophysical characterization presented here is well correlated with the enzymatic activity and provide new insight into the structural basis for the temperature and pH-dependent activity of the TpManGH5. Also, the data suggest a loop region that provides a starting point for a rational design of biotechnological desired features. PMID:25723179
Holographic Calculations of Euclidean Wilson Loop Correlator in Euclidean anti-de Sitter Space
Sannah Ziama
2015-01-12
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.
Martin Bojowald
2012-12-20
Inhomogeneous space-times in loop quantum cosmology have come under better control with recent advances in effective methods. Even highly inhomogeneous situations, for which multiverse scenarios provide extreme examples, can now be considered at least qualitatively.
NASA Astrophysics Data System (ADS)
Bojowald, Martin
2013-02-01
Inhomogeneous space-times in loop quantum cosmology have come under better control with recent advances in effective methods. Even highly inhomogeneous situations, for which multiverse scenarios provide extreme examples, can now be considered at least qualitatively.
Devised loop-in-loop technique in mitral valve repair.
Tokunaga, Shigehiko; Yasuda, Shota; Masuda, Munetaka
2014-11-01
The loop technique is useful for multiple chordal reconstructions in mitral valve repair. Although it is easy to anchor the loop to the tip of the prolapsed leaflet, take-down of the anchored loop is not easy. The devised loop-in-loop technique makes intraoperative adjustment of the neochordae quick and easy. This article describes a straightforward and reproducible method for secure anchoring and, if necessary, take-down of neochordae using the loop-in-loop technique for mitral valve repair. PMID:24887864
Feasibility study and optimum loading pattern of a multi-ring inflatable intravaginal applicator
Mehta, Keyur J.; Yaparpalvi, Ravindra; Hong, Linda; Mynampati, Dinesh; Tomé, Wolfgang A.; Kalnicki, Shalom
2013-01-01
Purpose A cylinder applicator is the standard treatment device for intravaginal brachytherapy. However, they are limited in their ability to simultaneously spare the organs at risk (OAR), and reduce the hot spot in the vaginal mucosa, while achieving adequate dose conformality. This study aims to compare the dosimetric characteristics of single and multi-channel cylinders, and utilizes volume point dose optimizations to investigate the feasibility and optimum loading method for a multi-ring inflatable intravaginal applicator. Material and methods Studies were designed to: (1) test the feasibility of multi-ring applicators, (2) compare dose distributions between different multi-channel applicators and loading patterns, (3) test non-uniform prescription depths around the multi-ring cylinder. Results Compared to a cylinder with a single central channel, a cylinder with 6 lumina arranged around the periphery, providing the lumina had adequate distance to the cylinder surface, could reduce dose beyond the prescription depth. However, when the number of outer lumina increased from 6 to 12, no further dose reduction could be achieved and the high dose volume close to the surface of the cylinder increased. Moreover, an additional ring, with lumina further away from the surface, provided increased dose shaping capabilities, allowing for individualized dose distributions. Conclusions Dose could be reduced to normal tissue and the inner mucosa, and better conformity was seen to unique anatomical shapes. A modified peripheral loading pattern provided the optimum dose distribution, yielding good conformity, dose sparing at adjacent organs, and dose reduction in the high dose region of the vaginal mucosa. PMID:23878554
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.
NSDL National Science Digital Library
VU Bioengineering RET Program, School of Engineering,
Students begin to focus on the torque associated with a current carrying loop in a magnetic field. They solve example problems as a class and use diagrams to visualize the vector product. In addition, students learn to calculate the energy of this loop in the magnetic field. Through the associated activity, "Get Your Motor Running," students explore a physical model to gain empirical data and compare it to their calculated data. A homework assignment is also provided as a means of student assessment.
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
Bootstrapping null polygon Wilson loops
NASA Astrophysics Data System (ADS)
Gaiotto, Davide; Maldacena, Juan; Sever, Amit; Vieira, Pedro
2011-03-01
We derive the two loop expressions for polygonal Wilson loops by starting from the one loop expressions and applying an operator product expansion. We do this for polygonal Wilson loops in R 1,1 and find a result in agreement with previous computations. We also discuss the spectrum of excitations around flux tube that connects two null Wilson lines.
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
Shape characterization of subdivision surfaces--case studies
Kestutis Karciauskas; Jörg Peters; Ulrich Reif
2004-01-01
For subdivision surfaces, it is important to characterize l ocal shape near flat spots and points where the surface is not twice continuously differentiable. Applying general principles de- rived in (PR0x), this paper characterizes shape near such points for the subdivision schemes devised by Catmull and Clark and by Loop. For generic input data, both schemes fail to converge to
NASA Technical Reports Server (NTRS)
Simon, M. K.; Alem, W. K.
1978-01-01
Unbalanced quadriphase-shift-keying (QPSK) is an attractive means for transmitting two digital data streams which in general have different average powers, data rates, and data formats. Previous analyses of the tracking performance of Costas loop demodulators of unbalanced QPSK have accounted only for the filtering effect produced by the loop's two arm filters on the equivalent additive noise perturbing the loop. When the bandwidth of these filters is selected on the basis of the order of the data rate, as is typical of optimum Costas loop design, the filtering degradations of the data modulations themselves and the cross-modulation noise produced by their multiplication in the loop often cannot be neglected. The purpose of this paper is to incorporate these additional filtering effects into the analysis. Many of the results obtained herein are in the form of closed-form expressions which can easily be evaluated numerically for design and performance prediction purposes.
Tim Koslowski
2013-01-09
Barbour's formulation of Mach's principle requires a theory of gravity to implement local relativity of clocks, local relativity of rods and spatial covariance. It turns out that relativity of clocks and rods are mutually exclusive. General Relativity implements local relativity of clocks and spatial covariance, but not local relativity of rods. It is the purpose of this contribution to show how Shape Dynamics, a theory that is locally equivalent to General Relativity, implements local relativity of rods and spatial covariance and how a BRST formulation, which I call Doubly General Relativity, implements all of Barbour's principles.
Lorce, C. [Departement d'Astrophysique, de Geophysique et d'Oceanographie, Universite de Liege, B5a, Sart-Tilman, B-4000 Liege (Belgium)
2008-08-29
Using a model based on the relativistic mean-field approach, we address the problem of baryon shape. The best option for unravelling a deviation from spherical symmetry being the study of the {gamma}N{delta} transition, we have evaluated its form factors at Q{sup 2} = 0. Our approach shows explicitly a quadrupolar distortion due to the pion cloud and quark angular momentum. Without any fits, we have obtained in the flavor SU(3) limit and up to the 5-quark level a nice agreement with experimental indications.
The optimum design configurations of Savonius wind turbines
Ushiyama, I.; Mino, M.; Nagai, H.
1982-08-01
This paper describes results of a systematic wind tunnel study aimed at development of an optimum configuration of Savonius rotor wind mill. Model tests were conducted in a wind tunnel on a number of Savonius rotor configurations in wind speed of 4 - 12m/s. The variables tested were blade aspect ratio, blade overlap, blade separation gap, profile of the rotor blade cross-section and the effect adding the guide vane. From this study, the power coefficient of the basic Savonius rotor is relatively low value of 0.15-0.20, with optimum blade configuration and guide vane, a maximum value of power coefficient of 0.34 was obtained and the results appears quite encouraging. Moreover, a special study was made of the flow visualization in a water channel to confirm the inference for the air flow patterns round and through the rotor.
An experimental study of an aerodynamically optimum windmill
NASA Astrophysics Data System (ADS)
Ishida, Y.; Toda, N.; Hoshino, H.; Noguchi, M.
1982-08-01
Aerodynamic characteristics of an optimum horizontal axis windmill are described. The windmill, rated at 20 KW at 8 m/s with a two bladed rotor of 14m diameter, is designed so as to vary the geometry of the blade in such a way that the aerodynamic efficiency becomes maximum. The combined blade element momentum theory is used as an analytical tool. To check the design method and get some useful aerodynamic data, a wind tunnel test of a 1/7th scale model (2m diameter) is performed in a low speed tunnel, whose test section is 35.75 sq m. Two models, whose blades have the same optimum chord distribution but have different planforms, are tested. Measurements are made of the efficiency, torque, axial drag force and initial torque for various combinations of the pitch angle and the tip speed ratio. The yaw characteristics of the windmill are also measured.
Optimum detection of an optical image on a photoelectric surface.
NASA Technical Reports Server (NTRS)
Helstrom, C. W.; Wang, L.
1973-01-01
The image-detecting performance of an optimum counting detector is compared with that of a 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 assumed to have a Gaussian spatial distribution. The optimum detector works with the pristine datum (and not with the photoelectric response) which is the spatiotemporal electromagnetic field at the aperture of the observing optical instrument. It is shown that little is to be gained by using details of the illuminance distribution beyond the crude knowledge of its breadth as embodied in a simple counter of emitted photoelectrons. All three detectors exhibit accordingly about the same reliability.
Implementation of an optimum profile guidance system on STOLAND
NASA Technical Reports Server (NTRS)
Flanagan, P. F.
1978-01-01
The implementation on the STOLAND airborne digital computer of an optimum profile guidance system for the augmentor wing jet STOL research aircraft is described. Major tasks were to implement the guidance and control logic to airborne computer software and to integrate the module with the existing STOLAND navigation, display, and autopilot routines. The optimum profile guidance system comprises an algorithm for synthesizing mimimum fuel trajectories for a wide range of starting positions in the terminal area and a control law for flying the aircraft automatically along the trajectory. The avionics software developed is described along with a FORTRAN program that was constructed to reflect the modular nature and algorthms implemented in the avionics software.
Design of helicopter rotor blades for optimum dynamic characteristics
NASA Technical Reports Server (NTRS)
Peters, D. A.; Ko, T.; Korn, A. E.; Rossow, M. P.
1983-01-01
The possibilities and limitations of tailoring blade mass and stiffness distributions to give an optimum blade design in terms of weight, inertia, and dynamic characteristics are discussed. The extent that changes in mass of stiffness distribution can be used to place rotor frequencies at desired locations is determined. Theoretical limits to the amount of frequency shift are established. Realistic constraints on blade properties based on weight, mass, moment of inertia, size, strength, and stability are formulated. The extent that the hub loads can be minimized by proper choice of E1 distribution, and the minimum hub loads which can be approximated by a design for a given set of natural frequencies are determined. Aerodynamic couplings that might affect the optimum blade design, and the relative effectiveness of mass and stiffness distribution on the optimization procedure are investigated.
A methodology for selecting optimum organizations for space communities
NASA Technical Reports Server (NTRS)
Ragusa, J. M.
1978-01-01
This paper suggests that a methodology exists for selecting optimum organizations for future space communities of various sizes and purposes. Results of an exploratory study to identify an optimum hypothetical organizational structure for a large earth-orbiting multidisciplinary research and applications (R&A) Space Base manned by a mixed crew of technologists are presented. Since such a facility does not presently exist, in situ empirical testing was not possible. Study activity was, therefore, concerned with the identification of a desired organizational structural model rather than the empirical testing of it. The principal finding of this research was that a four-level project type 'total matrix' model will optimize the effectiveness of Space Base technologists. An overall conclusion which can be reached from the research is that application of this methodology, or portions of it, may provide planning insights for the formal organizations which will be needed during the Space Industrialization Age.
Parallel operation of NH3 screw compressors - the optimum way
NASA Astrophysics Data System (ADS)
Pijnenburg, B.; Ritmann, J.
2015-08-01
The use of more smaller industrial NH3 screw compressors operating in parallel seems to offer the optimum way when it comes to fulfilling maximum part load efficiency, increased redundancy and other highly requested features in the industrial refrigeration industry today. Parallel operation in an optimum way can be selected to secure continuous operation and can in most applications be configured to ensure lower overall operating economy. New compressors are developed to meet requirements for flexibility in operation and are controlled in an intelligent way. The intelligent control system keeps focus on all external demands, but yet striving to offer always the lowest possible absorbed power, including in future scenarios with connection to smart grid.
Multilevel polarization shift keying: Optimum receiver structure and performance evaluation
Benedetto, S.; Poggiolini, P.T. [Politecnico di Torino (Italy)] [Politecnico di Torino (Italy)
1994-02-01
Multilevel digital coherent optical modulation schemes based on the state of polarization of a fully polarized lightwave are proposed and analyzed. Based on the complete statistical characterization of the Stokes parameters, extracted though appropriate signal processing in the presence of shot and additive gaussian noise, the optimum maximum likelihood receiver operating symbol by symbol is derived. The exact performance in terms of the average symbol error probability is found. Optimum constellations for the case of equipower 4, 8, 16 and 32 signals are found on the basis of the minimization of the error probability for a given average power. Their performance turns out to be promising as compared to other standard modulation techniques. The spectral analysis of polarization modulated signals is presented. A new receiver structure, which solves the problem of the excess penalties incurred in the presence of channel dichroism, is proposed and analyzed. 22 refs.
A new optimum topology switching dc-to-dc converter
NASA Technical Reports Server (NTRS)
Cuk, S.; Middlebrook, R. D.
1977-01-01
A novel switching dc-to-dc converter is presented, which has the same general conversion property (increase or decrease of the input dc voltage) as does the conventional buck-boost converter, and which offers through its new optimum topology higher efficiency, lower output voltage ripple, reduced EMI, smaller size and weight, and excellent dynamic response. One of its most significant advantages is that both input and output current are not pulsating but are continuous (essentially dc with small superimposed switching current ripple), thus resulting in a close approximation to the ideal physically nonrealizable dc-to-dc transformer. The converter retains the simplest possible structure with the minimum number of components which, when interconnected in its optimum topology, yield the maximum performance.
Fine Structures and Overlying Loops of Confined Solar Flares
NASA Astrophysics Data System (ADS)
Yang, Shuhong; Zhang, Jun; Xiang, Yongyuan
2014-10-01
Using the H? observations from the New Vacuum Solar Telescope at the Fuxian Solar Observatory, we focus on the fine structures of three confined flares and the issue why all the three flares are confined instead of eruptive. All the three confined flares take place successively at the same location and have similar morphologies, so can be termed homologous confined flares. In the simultaneous images obtained by the Solar Dynamics Observatory, many large-scale coronal loops above the confined flares are clearly observed in multi-wavelengths. At the pre-flare stage, two dipoles emerge near the negative sunspot, and the dipolar patches are connected by small loops appearing as arch-shaped H? fibrils. There exists a reconnection between the small loops, and thus the H? fibrils change their configuration. The reconnection also occurs between a set of emerging H? fibrils and a set of pre-existing large loops, which are rooted in the negative sunspot, a nearby positive patch, and some remote positive faculae, forming a typical three-legged structure. During the flare processes, the overlying loops, some of which are tracked by activated dark materials, do not break out. These direct observations may illustrate the physical mechanism of confined flares, i.e., magnetic reconnection between the emerging loops and the pre-existing loops triggers flares and the overlying loops prevent the flares from being eruptive.
Identification and Creation of Optimum Habitat Conditions for Livestock
Derek W. Bailey
2005-01-01
Abstract Optimum,habitat condition,is a concept,typically used for wildlife rather than livestock. The definition for optimal,livestock habitat will vary with management objectives. Abiotic factors, such as topography, water availability, and thermal cover, affect animal,performance,and uniformity,of grazing. Livestock usually prefer gentle slopes and avoid traveling long horizontal and vertical distances to water. Shade and nearby water are used for thermoregulation when temperatures
Pressure swing adsorption process: Performance optimum and adsorbent selection
Ravi Kumar
1994-01-01
Simulation results for an adsorptive gas separation process are presented. A feed gas mixture containing 25% methane and 75% hydrogen at a pressure of 20 atm is separated by a four-bed, nine-step pressure swing adsorption process to produce high purity hydrogen. The optimum operating conditions for producing maximum net product are identified. It is shown that improving mass-transfer characteristics of
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
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 Operation of In-Plant Cogeneration Systems
Craw, I. A.; Foster, D.; Reidy, K. D.
1987-01-01
model and a mathematical optimization package can determine the optimum settings for control variables of the power plant and eliminate uncertainties associated with achieving the minimum cost operation. TENSA Services and their parent company... developed over a 20 year period culminating with real time data collection and performance monitoring and real time optimization for a variety of plants, including heat and power cogeneration plants. ICI has found that they have been able to use...
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.
Generating AN Optimum Treatment Plan for External Beam Radiation Therapy.
NASA Astrophysics Data System (ADS)
Kabus, Irwin
1990-01-01
The application of linear programming to the generation of an optimum external beam radiation treatment plan is investigated. MPSX, an IBM linear programming software package was used. All data originated from the CAT scan of an actual patient who was treated for a pancreatic malignant tumor before this study began. An examination of several alternatives for representing the cross section of the patient showed that it was sufficient to use a set of strategically placed points in the vital organs and tumor and a grid of points spaced about one half inch apart for the healthy tissue. Optimum treatment plans were generated from objective functions representing various treatment philosophies. The optimum plans were based on allowing for 216 external radiation beams which accounted for wedges of any size. A beam reduction scheme then reduced the number of beams in the optimum plan to a number of beams small enough for implementation. Regardless of the objective function, the linear programming treatment plan preserved about 95% of the patient's right kidney vs. 59% for the plan the hospital actually administered to the patient. The clinician, on the case, found most of the linear programming treatment plans to be superior to the hospital plan. An investigation was made, using parametric linear programming, concerning any possible benefits derived from generating treatment plans based on objective functions made up of convex combinations of two objective functions, however, this proved to have only limited value. This study also found, through dual variable analysis, that there was no benefit gained from relaxing some of the constraints on the healthy regions of the anatomy. This conclusion was supported by the clinician. Finally several schemes were found that, under certain conditions, can further reduce the number of beams in the final linear programming treatment plan.
Towards AC-induced optimum control of dynamical localization
F. Revuelta; R. Chacón; F. Borondo
2014-09-15
It is shown that optimum control of dynamical localization (quantum suppression of classical diffusion) in the context of ultracold atoms in periodically shaken optical lattices subjected to time-periodic forces having equidistant zeros depends on the \\textit{impulse} transmitted by the external force over half-period rather than on the force amplitude. This result provides a useful principle for optimally controlling dynamical localization in general periodic systems, which is capable of experimental realization.
Sand deserts during glacial maximum and climatic optimum
Michael Sarnthein
1978-01-01
THE past 20,000 yr have witnessed tremendous climatic changes, a glacial maximum at about 18,000 yr BP and a climatic optimum centred on about 6,000 yr BP, both of which mark extreme situations for the Quaternary. This paper attempts to show that active sand dunes were extensive 18,000 yr ago. Conversely, it seems that sand dunes were generally dormant 6,000
Analysis of spent beam refocusing to achieve optimum collector efficiency
NASA Technical Reports Server (NTRS)
Stankiewicz, N.
1977-01-01
A reasonable criterion for evaluating the effectiveness of spent beam refocusing is the reduction of spent beam turbulence. The rms deviation of particle angles where the angles are calculated from the ratio of radial velocity to axial velocity is one measure of beam turbulence. It is demonstrated that the angular deviation can be reduced by almost half in some magnetic field configurations. Experimental evidence indicates that beam processing of this type is most likely to yield an optimum collector efficiency.
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.
Automated optimum design of wing structures. Deterministic and probabilistic approaches
NASA Technical Reports Server (NTRS)
Rao, S. S.
1982-01-01
The automated optimum design of airplane wing structures subjected to multiple behavior constraints is described. The structural mass of the wing is considered the objective function. The maximum stress, wing tip deflection, root angle of attack, and flutter velocity during the pull up maneuver (static load), the natural frequencies of the wing structure, and the stresses induced in the wing structure due to landing and gust loads are suitably constrained. Both deterministic and probabilistic approaches are used for finding the stresses induced in the airplane wing structure due to landing and gust loads. A wing design is represented by a uniform beam with a cross section in the form of a hollow symmetric double wedge. The airfoil thickness and chord length are the design variables, and a graphical procedure is used to find the optimum solutions. A supersonic wing design is represented by finite elements. The thicknesses of the skin and the web and the cross sectional areas of the flanges are the design variables, and nonlinear programming techniques are used to find the optimum solution.
Optimum design of optical fiber bundles for medical imaging
NASA Astrophysics Data System (ADS)
Arce-Diego, J. L.; Fanjul-Vélez, F.; Ortega-Quijano, N.; Pelayo-Fernández, M. L.; González-García, J.; Zorrilla de la Fuente, P.
2007-06-01
In this work, quality-limiting factors and optimum packing techniques in fiber bundles are studied, and they are applied to the design of imaging endoscopes in order to improve the image quality and achieve an optimum design, so that medical praxis based on these devices can be developed in a more reliable way. Quality-limiting factors in fiber bundles for medical imaging are analised. We find that leaky modes and interference between the optical fibers of the bundle have a close relationship with the length of the endoscope and opto-geometrical parameters of the fiber. They can be reduced using a steady state modes exciter and using a certain value of the distance between cores and the core diameter, respectively, as it will be studied. Optimum packing of the fibers is also very important to maximize the image area. We propose some structures and their efficiency is analised. It will be neccesary to reach an arrangement between core diameter, size of the cladding, and number of rings in the fiber bundle.
Optimum design of structures subject to general periodic loads
NASA Technical Reports Server (NTRS)
Reiss, Robert; Qian, B.
1989-01-01
A simplified version of Icerman's problem regarding the design of structures subject to a single harmonic load is discussed. The nature of the restrictive conditions that must be placed on the design space in order to ensure an analytic optimum are discussed in detail. Icerman's problem is then extended to include multiple forcing functions with different driving frequencies. And the conditions that now must be placed upon the design space to ensure an analytic optimum are again discussed. An important finding is that all solutions to the optimality condition (analytic stationary design) are local optima, but the global optimum may well be non-analytic. The more general problem of distributing the fixed mass of a linear elastic structure subject to general periodic loads in order to minimize some measure of the steady state deflection is also considered. This response is explicitly expressed in terms of Green's functional and the abstract operators defining the structure. The optimality criterion is derived by differentiating the response with respect to the design parameters. The theory is applicable to finite element as well as distributed parameter models.
All-fiber arbitrary and precise pulse spectral shaping
NASA Astrophysics Data System (ADS)
Wang, Shiwei; Zheng, Wanguo; Zhao, Lei; Zhu, Qihua; Xu, Jianqiu; Tang, Yulong
2015-04-01
A fiber-loop-based electro-optic (EO) modulation system is proposed and demonstrated to realize both broadband and high-resolution spectral shaping of laser pulses through direct phase modulation. With this fiber-loop EO modulator, arbitrary spectral shape can be carved and the modulation precision is up to 0.004?nm. The laser spectral bandwidth can be steadily broadened from several MHz to several nanometers through tuning the pulse cycle times and the programmable driving signal. One representative shaped spectrum is presented with a <0.01?nm mismatch to the simulated results, which is used to effectively pre-compensate the pulse spectral distortion during amplification.
Geometric Parameterization and Multiobjective Shape Optimization of Convective Periodic Channels
E. Nobile; F. Pinto; G. Rizzetto
2006-01-01
In this article we describe a general procedure for the geometric parameterization and multiobjective shape optimization of periodic wavy channels, representative of the repeating module of an ample variety of heat exchangers. The two objectives considered are the maximization of heat transfer rate and the minimization of friction factor. Since there is no single optimum to be found, we use
Loop electrosurgical excisional procedure.
Mayeaux, E J; Harper, M B
1993-02-01
Loop electrosurgical excisional procedure, or LEEP, also known as loop diathermy treatment, loop excision of the transformation zone (LETZ), and large loop excision of the transformation zone (LLETZ), is a new technique for outpatient diagnosis and treatment of dysplastic cervical lesions. This procedure produces good specimens for cytologic evaluation, carries a low risk of affecting childbearing ability, and is likely to replace cryotherapy or laser treatment for cervical neoplasias. LEEP uses low-current, high-frequency electrical generators and thin stainless steel or tungsten loops to excise either lesions or the entire transformation zone. Complication rates are comparable to cryotherapy or laser treatment methods and include bleeding, incomplete removal of the lesion, and cervical stenosis. Compared with other methods, the advantages of LEEP include: removal of abnormal tissue in a manner permitting cytologic study, low cost, ease of acquiring necessary skills, and the ability to treat lesions with fewer visits. Patient acceptance of the procedure is high. Widespread use of LEEP by family physicians can be expected. PMID:8426142
From Oligonucleotide Shapes to Genomic SELEX: Novel Biological Regulatory Loops
Larry Gold; David Brown; Yi-Yuan He; Timur Shtatland; Britta S. Singer; Yan Wu
1997-01-01
The SELEX method and oligonucleotide combinatorial chemistry discovery process yields high-affinity\\/high-specificity ligands for virtually any molecular target. Typically, the enormous starting libraries used in the SELEX process contain 1014-1015 sequences. We now ask if the smaller sequences, complexity of extant organisms, and evolutionary history provide useful interactions between oligonucleotides and at least some unexpected targets. That is, do organisms contain
Comparative Magnitude of Cross-Strain Conservation of HIV Variable Loop Neutralization Epitopes
James Swetnam; Evgeny Shmelkov; Susan Zolla-Pazner; Timothy Cardozo; Xia Jin
2010-01-01
Although the sequence variable loops of the human immunodeficiency virus' (HIV-1) surface envelope glycoprotein (gp120) can exhibit good immunogenicity, characterizing conserved (invariant) cross-strain neutralization epitopes within these loops has proven difficult. We recently developed a method to derive sensitive and specific signature motifs for the three-dimensional (3D) shapes of the HIV-1 neutralization epitopes in the third variable (V3) loop of
DNA Brushing Shoulders: Targeted Looping and Scanning of Large DNA Strands.
Azad, Zubair; Roushan, Maedeh; Riehn, Robert
2015-08-12
We present a nanofluidic device for targeted manipulations in the quarternary structure of single DNA molecules. We demonstrate the folding and unfolding of hairpin-shaped regions, similar to chromatin loops. These loops are stable for minutes at nanochannel junctions. We demonstrate continuous scanning of two DNA segments that occupy a common nanovolume. We present a model governing the stability of loop folds and discuss how the system achieves specific DNA configurations without operator intervention. PMID:26156085
A comparison of methods for DPLL loop filter design
NASA Technical Reports Server (NTRS)
Aguirre, S.; Hurd, W. J.; Kumar, R.; Statman, J.
1986-01-01
Four design methodologies for loop filters for a class of digital phase-locked loops (DPLLs) are presented. The first design maps an optimum analog filter into the digital domain; the second approach designs a filter that minimizes in discrete time weighted combination of the variance of the phase error due to noise and the sum square of the deterministic phase error component; the third method uses Kalman filter estimation theory to design a filter composed of a least squares fading memory estimator and a predictor. The last design relies on classical theory, including rules for the design of compensators. Linear analysis is used throughout the article to compare different designs, and includes stability, steady state performance and transient behavior of the loops. Design methodology is not critical when the loop update rate can be made high relative to loop bandwidth, as the performance approaches that of continuous time. For low update rates, however, the miminization method is significantly superior to the other methods.
Statistical study of twist values of transequatorial loops and the relationship with flares
Chen, Jie
Statistical study of twist values of transequatorial loops and the relationship with flares Jie, the twist values of `S'-shape transequatorial loops (TLs) from 1991 to 2001 are calculated, GOES soft X the twist value of the TLs has a weak relation with the flare flux. There is no clear correlation between
Automatic one-loop calculations with Sherpa+OpenLoops
NASA Astrophysics Data System (ADS)
Cascioli, F.; Höche, S.; Krauss, F.; Maierhöfer, P.; Pozzorini, S.; Siegert, F.
2014-06-01
We report on the OpenLoops generator for one-loop matrix elements and its application to four-lepton production in association with up to one jet. The open loops algorithm uses a numerical recursion to construct the numerator of one-loop Feynman diagrams as functions of the loop momentum. In combination with tensor integrals this results in a highly efficient and numerically stable matrix element generator. In order to obtain a fully automated setup for the simulation of next-to-leading order scattering processes we interfaced OpenLoops to the Sherpa Monte Carlo event generator.
NASA Astrophysics Data System (ADS)
Izzo, Dario; Petazzi, Lorenzo
2006-08-01
We present a satellite path planning technique able to make identical spacecraft aquire a given configuration. The technique exploits a behaviour-based approach to achieve an autonomous and distributed control over the relative geometry making use of limited sensorial information. A desired velocity is defined for each satellite as a sum of different contributions coming from generic high level behaviours: forcing the final desired configuration the behaviours are further defined by an inverse dynamic calculation dubbed Equilibrium Shaping. We show how considering only three different kind of behaviours it is possible to acquire a number of interesting formations and we set down the theoretical framework to find the entire set. We find that allowing a limited amount of communication the technique may be used also to form complex lattice structures. Several control feedbacks able to track the desired velocities are introduced and discussed. Our results suggest that sliding mode control is particularly appropriate in connection with the developed technique.
The Gluon Beam Function at Two Loops
Gaunt, Jonathan; Tackmann, Frank J
2014-01-01
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 ISR effects to the N-jettiness event shape through N^3LL order. We present numerical results for both the quark and gluon beam functions up to NNLO and N^3LL 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.
Open loop control on large stroke MEMS deformable mirrors
Alioune Diouf; Thomas G. Bifano; Andrew P. Legendre; Yang Lu; Jason B. Stewart
2010-01-01
Improvements for open-loop control of MEMS deformable mirror for large-amplitude wavefront control are presented. The improvements presented here relate to measurement filtering, characterization methods, and controlling the true, non-differential shape of the mirror. These improvements have led to increased accuracy over a wider variety of deflection profiles including flattening the mirror and Zernike polynomials.
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...
NASA Astrophysics Data System (ADS)
Vandersloot, Kevin
2006-05-01
In this thesis we present a detailed introduction to loop quantum cosmology focusing on the Robertson-Walker cosmologies with constant spatial curvature. The construction of the quantum theory will be presented starting from the classical reduction of the action and will not require prior knowledge of the loop quantum gravity. Particular attention will be paid to the detailed inputs and ambiguities of the quantization and the resulting consequences. We will uncover features of the theory that appear unphysical and propose a new quantization as well as interpretation of the theory that can solve these problems.
Jaume Gomis; Filippo Passerini
2006-12-10
We show that all half-BPS Wilson loop operators in N=4 SYM -- which are labeled by Young tableaus -- have a gravitational dual description in terms of D5-branes or alternatively in terms of D3-branes in AdS_5xS^5. We prove that the insertion of a half-BPS Wilson loop operator in the cal N=4 SYM path integral is achieved by integrating out the degrees of freedom on a configuration of bulk D5-branes or alternatively on a configuration of bulk D3-branes. The bulk D5-brane and D3-brane descriptions are related by bosonization.
Optimum Design of High Speed Prop-Rotors
NASA Technical Reports Server (NTRS)
Chattopadhyay, Aditi
1992-01-01
The objective of this research is to develop optimization procedures to provide design trends in high speed prop-rotors. The necessary disciplinary couplings are all considered within a closed loop optimization process. The procedures involve the consideration of blade aeroelastic, aerodynamic performance, structural and dynamic design requirements. Further, since the design involves consideration of several different objectives, multiobjective function formulation techniques are developed.
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
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.
Focal Plane Array Design For Optimum System Performance
NASA Astrophysics Data System (ADS)
Marshall, Donald E., Jr.
1980-06-01
Analytical expressions have been derived to simplify the design process for integrated focal planes. The focal plane parameters (detector size and CTD integration interval) are computed which peak system performance at a specific spatial frequency (fd). The spatial frequency is selected on the basis of target size and range and on an empirically derived relationship between recognition probability and cycles across the target. It is shown that a rectangular detector should have an angular subtense equal to 0.371/fd and that an ellptical detector should have a maximum dimension equal to 0.427/fd. In the case where a focal plane CTD integrator limits the electronics bandwidth, the optimum integration and sample interval is also 0.371/fd indicating that best performance is at one sample per detector dwell time. If a boxcar function is used in the scan direction for the display, and has a hold interval equal to the integration interval, the optimum integration and sample interval is 0.269/fd or 1.4 samples per dwell for the rectangular detector. The elliptical detector has slightly improved MRT and is slightly larger than the optimum rectangular detector. It has fabrication advantages for focal plane arrays using photovoltaic detectors. Signal aliasing is treated as a random noise source based on the fact that its impact on signal distortion is a function of the arbitrary phase relationship of the signal frequency and the sampling frequency. This model can be used to predict the MRT loss due to aliasing as a function of spatial frequency. At the design frequency (fd) a 5 percent loss in MRT is obtained for a rectangular detector and one sample per detector dwell time.
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
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.
ERIC Educational Resources Information Center
Chapman, Janet
1999-01-01
Recounts a teacher's experiences staying with the same group of children for more than one year (looping) as they progress through kindergarten and first grade. Discusses advantages of more stability and less trauma for the child, and more instructional time and less stress for the teacher. Addresses possible disadvantages of children having…
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.
Chromospheric 'active region loops'
NASA Astrophysics Data System (ADS)
Fang, C.; Martres, M. J.
1986-05-01
Based on 54 maps obtained at the Paris-Meudon Observatory, the emissive features detected in nine active regions (ARs) and observed on the disk at different levels of the chromosphere are studied, and 11 archshaped structures have been detected which may be interpreted as stable loops. The footpoints are located on both sides of an inversion region in the magnetic field, and it is suggested that the magnetic lines of force may have an oblique direction relative to the solar surface. The mean distance between the feet of the arches is about 30,000 km, with arch heights lower in the young AR, higher when it evolves, and scarcely detectable when the Ar is dying. The maximum peaks in the blue wing of the K line are noted at the periphery of the highest H-alpha and K3 intensity values or at the periphery of the AR, and observations of unstable loops during flares suggest a characteristic relationship between the stable loop and the transient flaring loop consisting of the flaring arch having one of its footpoints in common with a closer stable, preexisting arch at the maximum of the flares.
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
SIGMOID-TO-FLUX-ROPE TRANSITION LEADING TO A LOOP-LIKE CORONAL MASS EJECTION
Liu Rui; Liu Chang; Wang Shuo; Deng Na; Wang Haimin, E-mail: rui.liu@njit.ed [Space Weather Research Laboratory, Center for Solar-Terrestrial Research, NJIT, Newark, NJ 07102 (United States)
2010-12-10
Sigmoids are one of the most important precursor structures for solar eruptions. In this Letter, we study a sigmoid eruption on 2010 August 1 with EUV data obtained by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory (SDO). In AIA 94 A (Fe XVIII; 6 MK), topological reconfiguration due to tether-cutting reconnection is unambiguously observed for the first time, i.e., two opposite J-shaped loops reconnect to form a continuous S-shaped loop, whose central portion is dipped and aligned along the magnetic polarity inversion line (PIL), and a compact loop crossing the PIL. A causal relationship between photospheric flows and coronal tether-cutting reconnections is evidenced by the detection of persistent converging flows toward the PIL using line-of-sight magnetograms obtained by the Helioseismic and Magnetic Imager on board SDO. The S-shaped loop remains in quasi-equilibrium in the lower corona for about 50 minutes, with the central dipped portion rising slowly at {approx}10 km s{sup -1}. The speed then increases to {approx}60 km s{sup -1} about 10 minutes prior to the onset of a GOES-class C3.2 flare, as the S-shaped loop speeds up its transformation into an arch-shaped loop, which eventually leads to a loop-like coronal mass ejection. The AIA observations combined with H{alpha} filtergrams as well as hard X-ray imaging and spectroscopy are consistent with most flare loops being formed by reconnection of the stretched legs of less-sheared J-shaped loops that envelopes the rising flux rope, in agreement with the standard tether-cutting scenario.
Optimum Experimental Design for EGDM Modeled Organic Semiconductor Devices
Christoph Karl Felix Weiler; Stefan Körkel
2012-11-06
We apply optimum experimental design (OED) to organic semiconductors modeled by the extended Gaussian disorder model (EGDM) which was developed by Pasveer et al. We present an extended Gummel method to decouple the corresponding system of equations and use automatic differentiation to get derivatives with the required accuracy for OED. We show in two examples, whose parameters are taken from Pasveer et al. and Mensfoort and Coehoorn that the linearized confidence regions of the parameters can be reduced significantly by applying OED resulting in new experiments with a different setup.
Design optimum frac jobs using virtual intelligence techniques
NASA Astrophysics Data System (ADS)
Mohaghegh, Shahab; Popa, Andrei; Ameri, Sam
2000-10-01
Designing optimal frac jobs is a complex and time-consuming process. It usually involves the use of a two- or three-dimensional computer model. For the computer models to perform as intended, a wealth of input data is required. The input data includes wellbore configuration and reservoir characteristics such as porosity, permeability, stress and thickness profiles of the pay layers as well as the overburden layers. Among other essential information required for the design process is fracturing fluid type and volume, proppant type and volume, injection rate, proppant concentration and frac job schedule. Some of the parameters such as fluid and proppant types have discrete possible choices. Other parameters such as fluid and proppant volume, on the other hand, assume values from within a range of minimum and maximum values. A potential frac design for a particular pay zone is a combination of all of these parameters. Finding the optimum combination is not a trivial process. It usually requires an experienced engineer and a considerable amount of time to tune the parameters in order to achieve desirable outcome. This paper introduces a new methodology that integrates two virtual intelligence techniques, namely, artificial neural networks and genetic algorithms to automate and simplify the optimum frac job design process. This methodology requires little input from the engineer beyond the reservoir characterizations and wellbore configuration. The software tool that has been developed based on this methodology uses the reservoir characteristics and an optimization criteria indicated by the engineer, for example a certain propped frac length, and provides the detail of the optimum frac design that will result in the specified criteria. An ensemble of neural networks is trained to mimic the two- or three-dimensional frac simulator. Once successfully trained, these networks are capable of providing instantaneous results in response to any set of input parameters. These networks will be used as the fitness function for a genetic algorithm routine that will search for the best combination of the design parameters for the frac job. The genetic algorithm will search through the entire solution space and identify the optimal combination of parameters to be used in the design process. Considering the complexity of this task this methodology converges relatively fast, providing the engineer with several near-optimum scenarios for the frac job design. These scenarios, which can be achieved in just a minute or two, can be valuable initial points for the engineer to start his/her design job and save him/her hours of runs on the simulator.
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.
Optimum value of original events on the PEPT technique
Sadremomtaz, Alireza; Taherparvar, Payvand
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.
Optimum cruise lift coefficient in initial design of jet aircraft
Martinez-Val, R.; Perez, E. (Madrid, Universidad Politecnica (Spain))
1992-08-01
An attempt is made to develop a more realistic model of the optimum cruise of a jet aircraft by considering the effect of the Mach number on the specific fuel consumption. It is assumed that the specific fuel consumption is influenced by the Mach number in accordance with a potential law, which, along with the constant altitude constraint, allows a simple analytical treatment of the range equation and related expressions. The final results are written in closed form. An application of the results to performance prediction is illustrated. 12 refs.
Optimum discrimination problem and one solution to it
NASA Astrophysics Data System (ADS)
Caulfield, H. John
1998-10-01
Fourier optical pattern recognition has wonderful properties (high speed, space-invariant operation, low power consumption, target location) and one terrible property (It can work perfectly only for the rare, uninteresting case of two linearly separable categories). More powerful discrimination methods lack the other wonderful properties. I show here how to have it both ways at once. By using roughly the Vapnik- Chervonenkis (VC) dimension number of properly trained Fourier filters in parallel and performing pixel-by-pixel thresholding on the output planes, we can assemble a net output plane which achieves provably optimum, predictable discrimination on any sets.
Fiber lasers with loop reflectors
Urquhart, P. )
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.
Use of geostatistics in planning optimum drilling program
Ghose S. (AMAX Coal Industries, Indianapolis, IN (USA))
1989-08-01
Application of geostatistics in the natural resources industry is well established. In a typical process of estimation, the statistically dependent geological data are used to predict the characteristics of a deposit. The estimator used is the best linear unbiased estimator (or BLUE), and a numerical factor of confidence is also provided. The natural inhomogeneity and anisotropy of a deposit are also quantified with preciseness. Drilling is the most reliable way of obtaining data for mining and related industries. However, it is often difficult to decide what is the optimum number of drill holes necessary for evaluation. In this paper, sequential measures of percent variation at 95% confidence level of a geological variable have been used to decipher economically optimum drilling density. A coal reserve model has been used to illustrate the method and findings. Fictitious drilling data were added (within the domain of population characteristics) in stages, to obtain a point of stability, beyond which the gain was significant (diminishing marginal benefit). The final relations are established by graphically projecting and comparing two variables - cost and precision. By mapping the percent variation at each stage, the localized areas of discrepancies can be identified. These are the locations where additional drilling is needed. The system can be controlled if performed at progressive stages and the preciseness toward stability is monitored.
Optimum phase shift for quantitative phase microscopy in volume measurement.
Jafarfard, Mohammad Reza; Tayebi, Behnam; Lee, Seungrag; Bae, Yoon-Sung; Kim, Dug Young
2014-11-01
Volume measurement of a phase object is one of the most distinctive capabilities of quantitative phase microscopy (QPM). However, the accuracy of a measured volume is limited by the different noises of a measurement system and the finite bandpass filter used in the phase extraction algorithm. In this paper, we analyze the inherent errors in volume measurement with QPM and propose the optimum condition that can minimize these errors. We find that phase information of a sample in the frequency domain nonlinearly oscillates as a function of the phase shift corresponding to the sample and its medium, and that the phase information of a sample inside the bandpass filter can be maximized by a proper phase shift. Through numerical simulations and actual experiments, we demonstrate that the error in phase volume measurement can be effectively reduced by the enhancement of the phase signal inside the bandpass region using an optimum amount of phase, which can be controlled by changing either the medium index or the wavelength of illumination. PMID:25401354
[Optimum field observation data for simulating maize leaf area index].
Ma, Xue-Yan; Zhou, Guang-Sheng
2013-06-01
Leaf area index is a key indicator of leaf area change of crop population, and also, an important parameter for studying crop photosynthesis, transpiration, and biomass formation, etc. How to establish an optimum leaf area index (LAI) dynamic model with the minimum field observation data is of great significance for accurately simulating crop growth and yield. Based on the field experiment data of various spring maize varieties from the Jinzhou Agricultural Ecosystem Research Station in Northeast China in 2005-2011, in combination with the universal maize LAI dynamic model, this paper discussed the optimum field observation data for accurately simulating the dynamics of maize LAI. It was suggested that for the accurate simulation of the dynamics of maize LAI, the field observation should be no less than 3 years, with at least 4 times observation during the growth period each year. The proper four observation times during maize growth period were suggested as about 20 d after seedling emergence for the first observation, and monthly thereafter for the other three observations. This study could provide reference for conducting an effective observation on leaf area index and its dynamic modeling. PMID:24066543
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
Optimum take-off angle in the long jump.
Linthorne, Nicholas P; Guzman, Maurice S; Bridgett, Lisa A
2005-07-01
In this study, we found that the optimum take-off angle for a long jumper may be predicted by combining the equation for the range of a projectile in free flight with the measured relations between take-off speed, take-off height and take-off angle for the athlete. The prediction method was evaluated using video measurements of three experienced male long jumpers who performed maximum-effort jumps over a wide range of take-off angles. To produce low take-off angles the athletes used a long and fast run-up, whereas higher take-off angles were produced using a progressively shorter and slower run-up. For all three athletes, the take-off speed decreased and the take-off height increased as the athlete jumped with a higher take-off angle. The calculated optimum take-off angles were in good agreement with the athletes' competition take-off angles. PMID:16195020
Optimum dietary protein requirement of Malaysian mahseer (Tor tambroides) fingerling.
Misieng, Josephine Dorin; Kamarudin, Mohd Salleh; Musa, Mazlinda
2011-02-01
The optimum dietary protein requirement of the Malaysian mahseer (Tor tambroides) fingerlings was determined in this study. In this completely randomized designed experiment, formulated diets of five levels of dietary protein (30, 35, 40, 45 and 50%) were tested on the T. tambroides fingerlings (initial body weight of 5.85 +/- 0.40 g), reared in aquarium fitted with a biofiltering system. The fingerlings were fed twice daily at 5% of biomass. The fingerling body weight and total length was taken at every two weeks. Mortality was recorded daily. The dietary protein had significant effects on the body weight gain and Specific Growth Rate (SGR) of the fingerlings. The body weight gain and SGR of fingerlings fed with the diet with the dietary protein level of 40% was significantly higher (p<0.05) than that of 30, 35 and 50%. The feed conversion ratio of the 40% dietary protein was the significantly lowest at 2.19 +/- 0.163. The dietary protein level of 40% was the most optimum for T. tambroides fingerlings. PMID:21870647
Loop Heat Pipes and Capillary Pumped Loops: An Applications Perspective
NASA Technical Reports Server (NTRS)
Butler, Dan; Ku, Jentung; Swanson, Theodore; Obenschain, Arthur F. (Technical Monitor)
2001-01-01
Capillary pumped loops (CPLS) and loop heat pipes (LHPS) are versatile two-phase heat transfer devices which have recently gained increasing acceptance in space applications. Both systems work based on the same principles and have very similar designs. Nevertheless, some differences exist in the construction of the evaporator and the hydro-accumulator, and these differences lead to very distinct operating characteristics for each loop. This paper presents comparisons of the two loops from an applications perspective, and addresses their impact on spacecraft design, integration, and test. Some technical challenges and issues for both loops are also addressed.
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.
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.
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.
NASA Astrophysics Data System (ADS)
Opolski, Antoni
2014-12-01
Professor Antoni Opolski was actively interested in astronomy after his retirement in 1983. He especially liked to study the works of the famous astronomer Copernicus getting inspiration for his own work. Opolski started his work on planetary loops in 2011 continuing it to the end of 2012 . During this period calculations, drawings, tables, and basic descriptions of all the planets of the Solar System were created with the use of a piece of paper and a pencil only. In 2011 Antoni Opolski asked us to help him in editing the manuscript and preparing it for publication. We have been honored having the opportunity to work on articles on planetary loops with Antoni Opolski in his house for several months. In the middle of 2012 the detailed material on Jupiter was ready. However, professor Opolski improved the article by smoothing the text and preparing new, better drawings. Finally the article ''Loops of Jupiter'', written by the 99- year old astronomer, was published in the year of his 100th birthday.
NASA Astrophysics Data System (ADS)
Drukker, Nadav
2013-10-01
The generalized quark-antiquark potential of supersymmetric Yang-Mills theory on calculates the potential between a pair of heavy charged particles separated by an arbitrary angle on and also an angle in flavor space. It can be calculated by a Wilson loop following a prescribed path and couplings, or after a conformal transformation, by a cusped Wilson loop in flat space, hence also generalizing the usual concept of the cusp anomalous dimension. In this is calculated by an infinite open string. I present here an open spin-chain model which calculates the spectrum of excitations of such open strings. In the dual gauge theory these are cusped Wilson loops with extra operator insertions at the cusp. The boundaries of the spin-chain introduce a non-trivial reflection phase and break the bulk symmetry down to a single copy of . The dependence on the two angles is captured by the two embeddings of this algebra into , i.e., by a global rotation. The exact answer to this problem is conjectured to be given by solutions to a set of twisted boundary thermodynamic Bethe ansatz integral equations. In particular the generalized quark-antiquark potential or cusp anomalous dimension is recovered by calculating the ground state energy of the minimal length spin-chain, with no sites. It gets contributions only from virtual particles reflecting off the boundaries. I reproduce from this calculation some known weak coupling perturtbative results.
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).
Theoretical modelling of miniature loop heat pipe
NASA Astrophysics Data System (ADS)
Singh, Randeep; Akbarzadeh, Aliakbar; Dixon, Chris; Mochizuki, Masataka
2009-12-01
Development in the design and thermal performance of the loop heat pipes (LHPs) demands the corresponding improvement in the theoretical modeling capabilities of these devices. In this paper, mathematical model for assessing the thermal performance of the miniature LHPs (mLHPs) on the basis of the operating temperature and thermal resistance of the loop has been discussed in detail. In order to validate the theoretical model, a mLHP with the flat disk shaped evaporator, 30 mm in diameter and 10 mm thick, was developed and tested with nickel and copper wick structure. By comparison with experimental results, it was found that the theoretical model was able to predict the evaporator temperature and loop thermal resistance very well and within the uncertainties imposed by the underlying assumptions. The mathematical model can be used to validate the design of the mLHP and verify whether the proposed design is consistent with the maximum heat load capacity required for the intended application. In addition to this, the model can assists in understanding and refining the outcomes of the experimental studies.
The two-loop hemisphere soft function
Kelley, Randall; Schwartz, Matthew D; Zhu, Hua Xing
2011-01-01
The hemisphere soft function is calculated to order alpha_s^2. This is the first multi-scale soft function calculated to two loops. The renormalization scale dependence of the result agrees exactly with the prediction from effective field theory. This fixes the unknown coefficients of the singular parts of the two-loop thrust and heavy-jet mass distributions. There are four such coefficients, for 2 event shapes and 2 color structures, which are shown to be in excellent agreement with previous numerical extraction. The asymptotic behavior of the soft function has double logs in the CF CA color structure, which agree with non-global log calculations, but also has sub-leading single logs for both the CF CA and CF TF nf color structures. The general form of the soft function is complicated, does not factorize in a simple way, and disagrees with the Hoang-Kluth ansatz. The exact hemisphere soft function will remove one source of uncertainty on the alpha_s fits from e+e- event shapes.
On the Role of Intrinsic and Extrinsic Forces in Early Cardiac S-looping
Ramasubramanian, Ashok; Chu-LaGraff, Quynh B.; Buma, Takashi; Chico, Kevin T.; Carnes, Meagan E.; Burnett, Kyra R.; Bradner, Sarah A.; Gordon, Shaun S.
2014-01-01
Background Looping is a crucial phase during heart development when the initially straight heart tube is transformed into a shape that more closely resembles the mature heart. Although the genetic and biochemical pathways of cardiac looping are well-studied, the biophysical mechanisms that actually effect the looping process remain poorly understood. Using a combined experimental (chick embryo) and computational (finite element modeling) approach, we study the forces driving early s-looping when the primitive ventricle moves to its definitive position inferior to the common atrium. Results New results from our study indicate that the primitive heart has no intrinsic ability to form an s-loop and that extrinsic forces are necessary to effect early s-looping. They support previous studies that established an important role for cervical flexure in causing early cardiac s-looping. Our results also show that forces applied by the splanchnopleure cannot be ignored during early s-looping and shed light on the role of cardiac jelly. Using available experimental data and computer modeling, we successfully developed and tested a hypothesis for the force mechanisms driving s-loop formation. Conclusions Forces external to the primitive heart tube are necessary in the later stages of cardiac looping. Experimental and model results support our proposed hypothesis for forces driving early s-looping. PMID:23553909
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 and efficient sampling for variational quantum Monte Carlo
Trail, John Robert; 10.1063/1.3488651
2010-01-01
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 wavefunctions, that is to Variational quantum Monte Carlo. Almost all previous implementations employ samples distributed as the physical probability density of the trial wavefunction, and assume the Central Limit Theorem to be valid. In this paper we provide an analysis of random error in estimation and optimisation 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 optimisation. The method is ...
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
Pressure swing adsorption process: Performance optimum and adsorbent selection
Kumar, R. (Air Products and Chemicals, Inc., Allentown, PA (United States))
1994-06-01
Simulation results for an adsorptive gas separation process are presented. A feed gas mixture containing 25% methane and 75% hydrogen at a pressure of 20 atm is separated by a four-bed, nine-step pressure swing adsorption process to produce high purity hydrogen. The optimum operating conditions for producing maximum net product are identified. It is shown that improving mass-transfer characteristics of the adsorbent is helpful, but only up to a limit, after which it does not help to further reduce the mass-transfer resistance. It is also shown that the best adsorbent cannot be chosen by considering only the selectivity or working capacity. A combination of both of these properties is important. On the other hand, higher saturation capacity improves the performance of the simulated process.
Optimum compositions for thermal insulation of burners and regenerators
Zasypkin, V.I.; Popov, O.N.
1988-07-01
The thermal and mechanical properties of thermal insulation compositions applied by spraying were evaluated to determine the optimum composition for the parameters posed by the burners and regenerators of glass-melting furnaces. The effects of varying spray parameters on these properties were also assessed. Changes were made in the binder density while leaving the amount of filler unaltered. With an increase in binder density there was an increase in the apparent density of the insulation. Kaolin wool with an aluminoborophosphate concentrate binder was tested for thermal conductivity, apparent density, and bending, shear, and compression strength against asbestos with water glass as a binder. For walls of the regenerators and a single-layer heat insulation, insulation made from an asbestos-perlite mixture with water glass was recommended.
Incorporating spatial criteria in optimum reserve network selection.
Onal, Hayri; Briers, Robert A
2002-12-01
Considering the spatial location of sites that are to be selected for inclusion in a protected reserve network may be necessary to facilitate dispersal and long-term persistence of species in the selected sites. This paper presents an integer programming (IP) approach to the reserve network selection problem where spatial considerations based on intersite distances are taken into account when selecting reserve sites. The objective is to reduce the fragmentation of preserved sites and design a compact reserve network. Two IP formulations are developed which minimize the sum of pairwise distances and the maximum intersite distance between all sites in the reserve network, respectively, while representing all species under consideration. This approach is applied to a pond invertebrate dataset consisting of 131 sites containing 256 species in Oxfordshire, UK. The results show that significant reductions in reserve fragmentation can be achieved, compared with spatially unrestricted optimum reserve selection, at the expense of a small loss in reserve efficiency. PMID:12495486
Parametric Study of Water Rocket for Optimum Flight
NASA Astrophysics Data System (ADS)
Ota, Takayuki; Umemura, Akira
Parametric study is conducted to find the optimum condition of water rocket for long flight, provided that the tank volume is prescribed. The parameters considered in the present study are the initial air pressure, water volume fraction, empty rocket mass, launching angle and bottle diameter which significantly affect the flight performance of water rocket. First, we calculate the temporal changes in tank pressure, water and air issue speeds and thrust, on the basis of a simple physical model which has been experimentally validated. Then, this model is incorporated into the equation of motion to calculate the ballistic flight of water rocket with various parameter values. As a result, it is found that PET bottles in the market are one of the most suitable for use as the pressure tank of water rocket.
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 hot water temperature for absorption solar cooling
Lecuona, A.; Ventas, R.; Venegas, M.; Salgado, R.; Zacarias, A.
2009-10-15
The hot water temperature that maximizes the overall instantaneous efficiency of a solar cooling facility is determined. A modified characteristic equation model is used and applied to single-effect lithium bromide-water absorption chillers. This model is based on the characteristic temperature difference and serves to empirically calculate the performance of real chillers. This paper provides an explicit equation for the optimum temperature of vapor generation, in terms of only the external temperatures of the chiller. The additional data required are the four performance parameters of the chiller and essentially a modified stagnation temperature from the detailed model of the thermal collector operation. This paper presents and discusses the results for small capacity machines for air conditioning of homes and small buildings. The discussion highlights the influence of the relevant parameters. (author)
Variational methods in simultaneous optimum interpolation and initialization
NASA Technical Reports Server (NTRS)
Wahba, G.
1982-01-01
The duality between optimum interpolation and variational objective analysis, is reviewed. This duality is used to set up a variational approach to objective analysis which uses prior information concerning the atmospheric spectral energy distribution, in the variational problem. In the wind analysis example, the wind field is partitioned into divergent and nondivergent parts, and a control parameter governing the relative energy in the two parts is estimated from the observational data being analyzed by generalized cross validation, along with a bandwidth parameter. A variational approach to combining objective analysis and initialization in a single step is proposed. In a simple example of this approach, data, forecast, and prior information concerning atmospheric energy distribution is combined into a single variational problem. This problem has (at least) one bandwidth parameter, one partitioning parameter governing the relative energy in fast slow modes, and one parameter governing the relative weight to be given to observational and forecast data.
Optimum survival strategies against zombie infestations - a population dynamics approach
NASA Astrophysics Data System (ADS)
Mota, Bruno
2014-03-01
We model a zombie infestation by three coupled ODEs that jointly describe the time evolution of three populations: regular humans, zombies, and survivors (humans that have survived at least one zombie encounter). This can be generalized to take into account more levels of expertise and/or skill degradation. We compute the fixed points, and stability thereof, that correspond to one of three possible outcomes: human extinction, zombie extermination or, if one allows for a human non-zero birth-rate, co-habitation. We obtain analytically the optimum strategy for humans in terms of the model's parameters (essentially, whether to flee and hide, or fight). Zombies notwithstanding, this can also be seen as a toy model for infections of immune system cells, such as CD4+ T cells in AIDS, and macrophages in tuberculosis, whereby cells are both the target of infection, and mediate the acquired immunity response against the same infection. I thank FAPERJ for financial support.
A Decision Support System for Optimum Use of Fertilizers
Hoskinson, Reed Louis; Hess, John Richard; Fink, Raymond Keith
1999-07-01
The Decision Support System for Agriculture (DSS4Ag) is an expert system being developed by the Site-Specific Technologies for Agriculture (SST4Ag) precision farming research project at the INEEL. DSS4Ag uses state-of-the-art artificial intelligence and computer science technologies to make spatially variable, site-specific, economically optimum decisions on fertilizer use. The DSS4Ag has an open architecture that allows for external input and addition of new requirements and integrates its results with existing agricultural systems’ infrastructures. The DSS4Ag reflects a paradigm shift in the information revolution in agriculture that is precision farming. We depict this information revolution in agriculture as an historic trend in the agricultural decision-making process.
A Decision Support System for Optimum Use of Fertilizers
R. L. Hoskinson; J. R. Hess; R. K. Fink
1999-07-01
The Decision Support System for Agriculture (DSS4Ag) is an expert system being developed by the Site-Specific Technologies for Agriculture (SST4Ag) precision farming research project at the INEEL. DSS4Ag uses state-of-the-art artificial intelligence and computer science technologies to make spatially variable, site-specific, economically optimum decisions on fertilizer use. The DSS4Ag has an open architecture that allows for external input and addition of new requirements and integrates its results with existing agricultural systems' infrastructures. The DSS4Ag reflects a paradigm shift in the information revolution in agriculture that is precision farming. We depict this information revolution in agriculture as an historic trend in the agricultural decision-making process.
Optimum Transmission Policies for Battery Limited Energy Harvesting Nodes
Tutuncuoglu, Kaya
2010-01-01
Wireless networks with energy harvesting battery powered nodes are quickly emerging as a viable option for future wireless networks with extended lifetime. Equally important to their counterpart in the design of energy harvesting radios are the design principles that this new networking paradigm calls for. In particular, unlike wireless networks considered up to date, the energy replenishment process and the storage constraints of the rechargeable batteries need to be taken into account in designing efficient transmission strategies. In this work, we consider such transmission policies for rechargeable nodes, and identify the optimum solution for two related problems. Specifically, the transmission policy that maximizes the short term throughput, i.e., the amount of data transmitted in a finite time horizon is found. In addition, we show the relation of this optimization problem to another, namely, the minimization of the transmission completion time for a given amount of data, and solve that as well. The tra...
Optimum Actuator Selection with a Genetic Algorithm for Aircraft Control
NASA Technical Reports Server (NTRS)
Rogers, James L.
2004-01-01
The placement of actuators on a wing determines the control effectiveness of the airplane. One approach to placement maximizes the moments about the pitch, roll, and yaw axes, while minimizing the coupling. For example, the desired actuators produce a pure roll moment without at the same time causing much pitch or yaw. For a typical wing, there is a large set of candidate locations for placing actuators, resulting in a substantially larger number of combinations to examine in order to find an optimum placement satisfying the mission requirements and mission constraints. A genetic algorithm has been developed for finding the best placement for four actuators to produce an uncoupled pitch moment. The genetic algorithm has been extended to find the minimum number of actuators required to provide uncoupled pitch, roll, and yaw control. A simplified, untapered, unswept wing is the model for each application.
Optimum periodicity of repeated contractile actions applied in mass transport
NASA Astrophysics Data System (ADS)
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.
OPTIMUM DESIGN OF GROYNES FOR STABILIZATION OF LOWLAND RIVERS
NASA Astrophysics Data System (ADS)
Alauddin, Mohammed; Tsujimoto, Tetsuro
Alluvial rivers at low land as in Bangladesh are highly dynamic in nature; where huge landloss due to severe bank erosion at high flood as well as repeated interruptions of navigation system due to rapid sedimentation at low flow are very common. Groynes, revetments etc. are typically used to overcome these problems, but the goals are not achieved as expected. This study investigates the optimum design of a groyne for its effective functioning. A 2D model, RIC-Nays is utilized in this study upon confirmation. The channel and flow parameters are based on conformity to a typical river of Bangladesh. Four orientations and three configurations of groynes are considered here. The performance of groynes is evaluated through three key indices erosion in channel bed (thalweg), deposition in groyne field, and scour near groyne-tip. Computations reveal that a modified groyne functions better over the straight ones through protection of channel bank from erosion and maintenance of navigation channel as well.
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 design of a nanoscale spin-Seebeck power device.
Liao, Tianjun; Lin, Jian; Su, Guozhen; Lin, Bihong; Chen, Jincan
2015-05-01
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. PMID:25865604
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
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.
Optimized conical shaped charge design using the SCAP (Shaped Charge Analysis Program) code
Vigil, M.G.
1988-09-01
The Shaped Charge Analysis Program (SCAP) is used to analytically model and optimize the design of Conical Shaped Charges (CSC). A variety of existing CSCs are initially modeled with the SCAP code and the predicted jet tip velocities, jet penetrations, and optimum standoffs are compared to previously published experimental results. The CSCs vary in size from 0.69 inch (1.75 cm) to 9.125 inch (23.18 cm) conical liner inside diameter. Two liner materials (copper and steel) and several explosives (Octol, Comp B, PBX-9501) are included in the CSCs modeled. The target material was mild steel. A parametric study was conducted using the SCAP code to obtain the optimum design for a 3.86 inch (9.8 cm) CSC. The variables optimized in this study included the CSC apex angle, conical liner thickness, explosive height, optimum standoff, tamper/confinement thickness, and explosive width. The non-dimensionalized jet penetration to diameter ratio versus the above parameters are graphically presented. 12 refs., 10 figs., 7 tabs.
Shape tuning of adaptive structures for MEMS actuator applications
NASA Astrophysics Data System (ADS)
Ma, Zhichun; Lee, Yung-Cheng
2005-05-01
This paper describes a systematic shape tuning procedure of adaptive structures for MEMS actuator applications. Due to fabrication process variations, MEMS devices can have different shapes with varied deflections. Such shape variations should be corrected for specific applications. As a result, it is necessary to establish a shape tuning procedure. Finite element modeling and optimization approach were used to minimize the shape variations. The procedure integrated Python programming, ABAQUS, and optimization algorithm for engineering applications. It used the powerful Python scripts programming, the vast library of ABAQUS functions, and a robust preexisting optimization algorithm, NLPQL, which provides more efficient, flexible, and systematic tools for optimization problems. Optimization was used in the adaptive structural designs and the shape tuning procedure after the assembly. Using this approach, three bimorph, gold-on-polysilicon, samples with different initial shapes were studied for shape tuning. The shape was characterized by maximum tip deflection resulting from thermo-mechanical deformations. The standard deviation of the shape variations was reduced from 1.21 to 0.05 ?m after tuning. This reduction was verified by experimental data. Another case with ten devices was studied to confirm the effectiveness of the procedure. The standard deviation of the deflections was reduced from 0.81 to 0.02 ?m after tuning. These results demonstrated the effectiveness of the optimum procedure for shape tuning. This general-purpose systematic methodology can be applied to adaptive structures for a variety of aerospace applications.
Hutchinson incisors; Abnormal tooth shape; Peg teeth; Mulberry teeth; Conical teeth ... The appearance of normal teeth varies, especially the molars. ... conditions. Specific diseases can affect tooth shape, tooth ...
OPTIMUM HULL SPACING OF A FAMILY OF MULTIHULLS
Stokes, Yvonne
to generated wave amplitude, wave resistance, and total drag. Keywords: multihulls, catamarans, ship waves prescribed patch aft of the vessel), wave resistance, and total drag. This is done over a large range for a simplescaling of osets. That is, they have the same length, draft, and shape, but can have dierent beams
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.
Beam shaping for holographic techniques
NASA Astrophysics Data System (ADS)
Laskin, Alexander; Laskin, Vadim; Ostrun, Aleksei
2014-09-01
Uniform intensity of laser radiation is very important in holographic and interferometry technologies, therefore transformation of typical Gaussian distribution of a TEM00 laser to flat-top (top hat) is an actual technical task, it is solved by applying beam shaping optics. Holography and interferometry have specific requirements to a uniform laser beam, most important of them are flatness of phase front and extended depth of field. There are different refractive and diffractive beam shaping approaches used in laser industrial and scientific applications, but only few of them are capable to fulfil the optimum conditions for beam quality demanding holography and interferometry. We suggest applying refractive field mapping beam shapers piShaper, which operational principle presumes almost lossless transformation of Gaussian to flat-top beam with flatness of output wavefront, conserving of beam consistency, providing collimated low divergent output beam, high transmittance, extended depth of field, negligible wave aberration, and achromatic design provides capability to work with several lasers with different wavelengths simultaneously. This approach is used in SLM-based technologies of Computer Generated Holography, Dot-Matrix mastering of security holograms, holographic data storage, holographic projection, lithography, interferometric recording of Volume Bragg Gratings. High optical quality of resulting flat-top beam allows applying additional optical components to vary beam size and shape, thus adapting an optical system to requirements of a particular application. This paper will describe design basics of refractive beam shapers and optical layouts of their applying in holographic systems. Examples of real implementations and experimental results will be presented as well.
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
Mirror Symmetry And Loop Operators
Benjamin Assel; Jaume Gomis
2015-06-04
Wilson loops in gauge theories pose a fundamental challenge for dualities. Wilson loops are labeled by a representation of the gauge group and should map under duality to loop operators labeled by the same data, yet generically, dual theories have completely different gauge groups. In this paper we resolve this conundrum for three dimensional mirror symmetry. We show that Wilson loops are exchanged under mirror symmetry with Vortex loop operators, whose microscopic definition in terms of a supersymmetric quantum mechanics coupled to the theory encode in a non-trivial way a representation of the original gauge group, despite that the gauge groups of mirror theories can be radically different. Our predictions for the mirror map, which we derive guided by branes in string theory, are confirmed by the computation of the exact expectation value of Wilson and Vortex loop operators on the three-sphere.
Mirror Symmetry And Loop Operators
Assel, Benjamin
2015-01-01
Wilson loops in gauge theories pose a fundamental challenge for dualities. Wilson loops are labeled by a representation of the gauge group and should map under duality to loop operators labeled by the same data, yet generically, dual theories have completely different gauge groups. In this paper we resolve this conundrum for three dimensional mirror symmetry. We show that Wilson loops are exchanged under mirror symmetry with Vortex loop operators, whose microscopic definition in terms of a supersymmetric quantum mechanics coupled to the theory encode in a non-trivial way a representation of the original gauge group, despite that the gauge groups of mirror theories can be radically different. Our predictions for the mirror map, which we derive guided by branes in string theory, are confirmed by the computation of the exact expectation value of Wilson and Vortex loop operators on the three-sphere.
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.
Optimum conditions for prebiotic evolution in extraterrestrial environments
NASA Astrophysics Data System (ADS)
Abbas, Ousama H.
The overall goal of the dissertation was to devise synthetic pathways leading to the production of peptides and amino acids from smaller organic precursors. To this end, eight different zeolites were tested in order to determine their catalytic potential in the conversion of amino acids to peptides. The zeolites tested were either synthetic or naturally occurring. Acidic solutions of amino acids were prepared with or without zeolites and their reactivity was monitored over a four-week time interval. The kinetics and feasibility of peptide synthesis from selected amino acid combinations was investigated via the paper chromatography technique. Nine different amino acids were tested. The nature and extent of product were measured at constant time intervals. It was found that two ZSM-5 synthetic zeolites as well as the Fisher Scientific zeolite mix without alumina salts may have a catalytic potential in the conversion of amino acids to peptides. The conversion was verified by matching the paper chromatogram of the experimental product with that of a known peptide. The experimental results demonstrate that the optimum solvent system for paper chromatographic analysis of the zeolite-catalyzed self-assembly of the amino acids L-aspartic acid, L- asparagine, L-histidine, and L-serine is a 50:50 mixture of 1-butanol and acetone by volume. For the amino acids L-alanine, L-glycine, and L-valine, the optimum solvent was found to be a 30:70 mixture of ammonia and propanol by volume. A mathematical model describing the distance traveled (spot position) versus reaction time was constructed for the zeolite-catalyzed conversion of L- leucine and L-tyrosine and was found to approximately follow the function f(t) = 25 ln t. Two case studies for prebiotic synthesis leading to the production of amino acids or peptides in extraterrestrial environments were discussed: one involving Saturn's moon Titan, and the other involving Jupiter's moon Europa. In the Titan study, it was determined that organic synthesis, based on simple precursors, may lead in the Titan environment to the production of biologically important molecules such as amino acids. In the Europa study, three synthetic schemes using hydrogen peroxide, sulfuric acid, and hydrocyanic acid, and leading to the production of larger biologically important molecules such as amino acids were presented. (Abstract shortened by UMI.)
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.
Ekpyrotic loop quantum cosmology
Wilson-Ewing, Edward, E-mail: wilson-ewing@phys.lsu.edu [Department of Astronomy and Physics, Louisiana State University, Baton Rouge, 70803 (United States)
2013-08-01
We consider the ekpyrotic paradigm in the context of loop quantum cosmology. In loop quantum cosmology the classical big-bang singularity is resolved due to quantum gravity effects, and so the contracting ekpyrotic branch of the universe and its later expanding phase are connected by a smooth bounce. Thus, it is possible to explicitly determine the evolution of scalar perturbations, from the contracting ekpyrotic phase through the bounce and to the post-bounce expanding epoch. The possibilities of having either one or two scalar fields have been suggested for the ekpyrotic universe, and both cases will be considered here. In the case of a single scalar field, the constant mode of the curvature perturbations after the bounce is found to have a blue spectrum. On the other hand, for the two scalar field ekpyrotic model where scale-invariant entropy perturbations source additional terms in the curvature perturbations, the power spectrum in the post-bounce expanding cosmology is shown to be nearly scale-invariant and so agrees with observations.
[Selection of optimum periods for rice estimation using remote sensing data based on GIS].
Huang, Jingfeng; Wang, Renchao; Jiang, Hengxian; Yang, Zhong'en
2002-03-01
The optimum temporal for rice estimation using remote sensing data included the optimum temporal for rice planting area estimation and the optimum temporal for rice yield estimation. Based on GIS, the rice potential planting area was extracted. Therefore, the study area became smaller and the plant species considered decreased. So the optimum temporal for rice planting area estimation were determined through comparing the crop phonological calendars. In order to select the optimum temporal for rice yield estimation using remote sensing data, the relationships between the rice yield and agronomic parameters, the agronomic parameters and spectral variables, the rice yield and spectral variables for different development stages using field experiment data in 1989 and 1990 were studied. The result showed that the key period of rice production was from boot stage to heading stage. At last, the optimum temporal for rice yield estimation using remote sensing data was selected using the rice phenological calendars of 1998. PMID:12132155
Ullrich, Paul
16 4 Davis Bike Loop BIKING TOUR WALKING TOUR N North Entry Hunt Plant & Environmental Sciences Building Smart Purchasing Energy Infrastructure Geothermal Solar Photovoltaic Climate Action Collections
NASA Astrophysics Data System (ADS)
Blanco-Pillado, Jose J.; Olum, Ken D.; Shlaer, Benjamin
2014-01-01
Using recent simulation results, we provide the mass and speed spectrum of cosmic string loops. This is the quantity of primary interest for many phenomenological signatures of cosmic strings, and it can be accurately predicted using recently acquired detailed knowledge of the loop production function. We emphasize that gravitational smoothing of long strings plays a negligible role in determining the total number of existing loops. We derive a bound on the string tension imposed by recent constraints on the stochastic gravitational wave background from pulsar timing arrays, finding G? ?2.8×10-9. We also provide a derivation of the Boltzmann equation for cosmic string loops in the language of differential forms.
Decision algorithm for 3D blood vessel loop based on a route edit distance
NASA Astrophysics Data System (ADS)
Kobayashi, D.; Yokota, H.; Morishita, S.; Hiraoka, K.; Fukasaku, K.; Himeno, R.; Mishima, T.
2009-02-01
This paper reports on a method to distinguish true from false of the loop in the blood vessel graph. Most conventional studies have used a graph to represent 3D blood vessels structure. Blood vessels graph sometimes has a false loop and this exerts a harmful influence to the graph analysis. Conventional study simply cut them but this is not suitable for the graph include real loop. For this reason, we try to distinguish true from false of the loop in the graph. Our method uses the loop inside and the outside main blood vessel shape to distinguish the similar loop. This main blood vessel we called route is long, thick, and not shares to other route as much as possible. Even if a graph includes false loop, this main route will avoid the false connection and detect the same main blood vessel. Our method detects such a main route in each loop branch point and stores it as the outside feature for comparing. Inside feature is measured by converting the inside blood vessels as one route. Each loop is compared by the graph edit distance. Graph edit distance is easily able to deal with the route adding, deleting and replacing. Our method was tested by the cerebral blood vessels image in MRI. Our method tried to detect the arterial cycles of Willis from the graph including false loops. As a result, our method detected it correctly in four data from five.
A new model for E-mode power PHEMT and its optimum loading operation
C. J. Wei; Y. A. Tkachenko; D. Bartle
1999-01-01
Optimum loading for a power E-mode PHEMT is determined by a systematic harmonic load-pull simulation. The simulation uses a modified Angelov-Statz model that can accurately predict DC, small-signal RF, and power performance of the devices. The optimum second harmonic loading is found at open circuit and the optimum third harmonic is at the third quadrant, for a 2 mm device,
Determination of optimum operation cases in electric arc welding machine using neural network
Tahir Çetin Akinci; Hidir Selçuk No?ay; Gökhan Gökmen
2011-01-01
With arc welding machines, welding is only performed at optimum operating points. Determination of optimum operating points\\u000a is important so as for welding machines which will be produced in future to be developed in a manner to operate in such parts.\\u000a In this study, an Artificial Neutral Networks method was used in order to determine the optimum operating points of
Mercury's shape from radio occultations
NASA Astrophysics Data System (ADS)
Perry, M. E.; Kahan, D. S.; Barnouin, O. S.; Ernst, C. M.; Roberts, J. H.; Neumann, G. A.; Mazarico, E.; Hauck, S. A.; Solomon, S. C.; Zuber, M. T.; Smith, D. E.; Phillips, R. J.; Asmar, S. W.; Gaskell, R. W.; Oberst, J.; Preusker, F.
2012-09-01
To support studies of Mercury's internal structure, a MESSENGER mission goal is to measure the shape of the planet. Radio-frequency occultation observations contribute to this objective, particularly in most of the southern hemisphere where there are no altimeter data. We describe the techniques used to derive radius measurements from occultations and report results to date on the long-wavelength shape of Mercury. Before the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission, Mercury's shape was poorly constrained, primarily by Earth-based radar observations at low Mercury latitudes. During MESSENGER's 12-month primary mission, the Mercury Laser Altimeter (MLA) acquired an extensive data set on the topography of Mercury's northern hemisphere [1]. However, most of the southern hemisphere is beyond MLA range because the periapsis of MESSENGER's highly inclined, eccentric orbit is at high northern latitudes. Along with limb measurements and global stereo mosaics, occultation-derived radius measurements are essential for understanding the shape of Mercury's southern hemisphere. As viewed from Earth, the MESSENGER spacecraft passed behind Mercury every twelve hours for most of the primary mission. This geometry caused Mercury to occult the radio frequency (RF) transmissions, and we used an open-loop receiver to record RF power at the ingress and egress of each occultation. Incorporating the effects of diffraction, we extracted the time of occultation and used it to determine the RF path that grazed Mercury's surface. The point on that RF path that is tangent to the surface defines a unique latitude, longitude, and radius. Since the highest point along the RF path provides the occultation edge, the radius measurements are biased high relative to the surrounding terrain. We corrected for this bias by evaluating topography local to the tangent point. Digital-elevation models (DEMs), derived from surface images acquired by MESSENGER's Mercury Dual Imaging System (MDIS), contain the necessary topographic data. We compared northern-hemisphere occultation results to MLA data to verify the analysis approach and quantify uncertainty.
Transverse, Propagating Velocity Perturbations in Solar Coronal Loops
De Moortel, I; Wright, A N; Hood, A W
2015-01-01
This short review paper gives an overview of recently observed transverse, propagating velocity perturbations in coronal loops. These ubiquitous perturbations are observed to undergo strong damping as they propagate. Using 3D numerical simulations of footpoint-driven transverse waves propagating in a coronal plasma with a cylindrical density structure, in combination with analytical modelling, it is demonstrated that the observed velocity perturbations can be understood in terms of coupling of different wave modes in the inhomogeneous boundaries of the loops. Mode coupling in the inhomogeneous boundary layers of the loops leads to the coupling of the transversal (kink) mode to the azimuthal (Alfven) mode, observed as the decay of the transverse kink oscillations. Both the numerical and analytical results show the spatial profile of the damped wave has a Gaussian shape to begin with, before switching to exponential decay at large heights. In addition, recent analysis of CoMP (Coronal Multi-channel Polarimeter)...
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 viscous flow in pressure-swirl atomizers
NASA Astrophysics Data System (ADS)
Amini, Ghobad; Pereira, Aaron; Yun, Sangsig; Li, Xianguo
2013-11-01
Due to their simple configuration and reliable operation, pressure-swirl atomizers are widely used in applications such as combustion, painting, humidification, and sprinkling. The liquid is swirled by entering into the atomizer tangentially and its surface area is increased as discharges in a large spray angle. Understanding the effects of nozzle geometry and inlet flow condition on the discharge coefficient and spray angle is very important in nozzle design. To this end, the flow field inside a pressure-swirl atomizer has been studied theoretically. The main body of the liquid is taken to be moving in circles round the axis. Within the boundary layer, containing transverse and longitudinal velocity components, the retarded liquid is slowed down by viscosity and driven towards the exit orifice by pressure gradient. The swirling motion of liquid creates a low pressure zone near the nozzle axis and leads to the formation of a helical air-core. Through studying the growth of the boundary layer from nozzle entry to the orifice exit, the portions of the outflow exits the orifice from boundary layer current and also from the main body of the swirling liquid are specified. For a given range of pressure drop values, the optimum nozzle geometry and liquid flowrate are predicted. Additionally, the reason of increasing the flow by increasing liquid viscosity or decreasing orifice diameter is explained. A series of experiments and numerical modeling have also been carried out to support the theoretical results.
Assessment of optimum aquatic microcosm design for pollution impact studies
Harte, J.; Levy, D.; Rees, J.; Saegebarth, E.
1981-08-01
A series of experiments was carried out to evaluate optimum design and operating conditions for pelagic lake microcosms and to explore a possible use of such systems for toxicological testing. Criteria selected for microcosm optimization were realism and replicability of identically initiated microcosms. In the assessment studies, a number of different pelagic microcosm configurations were studied, including the size of the microcosm containers, the method of algal surface-growth prevention, and the degree of water mixing and aeration. In addition, the microcosm-lake comparisons were carried out in various seasons of the years to determine the influence of natural seasonal factors on the chemical and biological differences between the lakes and microcosms. In all but the smallest microcosms, surface-growth prevention removed size dependence. Chemical nutrients tracked well except during periods when nutrient inputs to the lake from the surrounding watershed were high. Good tracking of phytoplankton succession patterns was observed only when the physical conditions of the lake matched well with those in the laboratory system. In the decomposition studies, additions of dead organic matter to the lake microcosms were made, and the subsequent response of mineralization activity was measured. Highly replicable and interesting short-term behavior was seen, implying that protocols can be developed for microcosm testing of effects of toxicants on mineralization rates. On the basis of the microcosm assessment and decomposition studies, it was concluded that appropriate applications of pelagic microcosms are limited, and those applications that are most appropriate are delineated.
Selecting sprouts of brassicaceae for optimum phytochemical composition.
Baenas, Nieves; Moreno, Diego A; García-Viguera, Cristina
2012-11-14
Cruciferous foods (Brassicaceae spp.) are rich in nutrients and bioactive compounds. Edible sprouts are becoming popular fresh foods and, therefore, the phytochemical profiling of nine varieties of Brassicaceae (broccoli, kohlrabi, red cabbage, rutabaga, turnip, turnip greens, radish, garden cress, and white mustard) was evaluated for this purpose. The glucosinolates in seeds were significantly higher than in sprouts, and day 8 of germination was considered the optimum for consumption. The sprouts with higher concentrations of glucosinolates in 8-day-old sprouts were white mustard, turnip, and kohlrabi (?815, ?766, and ?653 mg 100 g?¹ FW, respectively). Red cabbage and radish presented great total glucosinolates content (?516 and ?297 mg 100 g?¹ FW, respectively, in 8-day-old sprouts) and also higher total phenolic contents, biomass, and antioxidant capacity. The selection of the best performers in terms of germination quality and phytochemical composition is the key to optimize new fresh foods enriched in health-bioactive compounds. Further research on the bioavailability of the bioactive compounds in Brassica foods will allow backing of recommendations for dietarily effective dosages for nutrition and health. PMID:23061899
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.
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.
Optimum. Delta. P and. Delta. T in heat exchange
Steinmeyer, D. )
1992-04-01
This paper reports that the place to begin any heat exchanger design is by asking about economic leverage. Where can the designer create more savings for his investment in time Frequently, selection of design numbers for heat transfer driving force is one of the most important decision the makes. But this rarely gets recognized. Perhaps the explanation is that driving force losses are hard to see. Part of the reason that the driving force problem is avoided is that it seems incredibly difficult. It is much easier than it seems. Both temperature difference ({Delta}T) and pressure drop ({Delta}P) have economic optima-low points on the total cost curve. Both are relatively easy to calculate, and both calculations are relatively forgiving. The curves are fairly gentle in the region of the optimum. However, they do not forgive: Using liquid rules of thumb for gases, Forgetting that refrigeration can be an extremely costly utility, Forgetting that a waste heat boiler, a feed-effluent exchanger and a reboiler have different criteria.
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 Heart Rate to Minimize Pulsatile External Cardiac Power
NASA Astrophysics Data System (ADS)
Pahlevan, Niema; Gharib, Morteza
2011-11-01
The workload on the left ventricle is composed of steady and pulsatile components. Clinical investigations have confirmed that an abnormal pulsatile load plays an important role in the pathogenesis of left ventricular hypertrophy (LVH) and progression of LVH to congestive heart failure (CHF). The pulsatile load is the result of the complex dynamics of wave propagation and reflection in the compliant arterial vasculature. We hypothesize that aortic waves can be optimized to reduce the left ventricular (LV) pulsatile load. We used an in-vitro experimental approach to investigate our hypothesis. A unique hydraulic model was used for in-vitro experiments. This model has physical and dynamical properties similar to the heart-aorta system. Different compliant models of the artificial aorta were used to test the hypothesis under various aortic rigidities. Our results indicate that: i) there is an optimum heart rate that minimizes LV pulsatile power (this is in agreement with our previous computational study); ii) introducing an extra reflection site at the specific location along the aorta creates constructive wave conditions that reduce the LV pulsatile power.
Determination of optimum annular gap for minimum heat losses
Yu Yiqin; Cao Huiling; Yang Hua; Qui Lin [Hebei Inst. of Tech., Tianjin (China). Dept. of Power Machinery Engineering
1995-12-31
This paper describes an experimental research of natural convective heat transfer in annular cylinders. The major components of the experimental apparatus are a series of annuluses consisting of concentric cylinders, end plates, main heater, associated heaters, cooling water jacket, and surveying instruments. The radius ratios of the annuluses (K) are 3.61, 2.95, 2.37, 1.85, 1.48, 1.21. The height-to-gap ratios (cylinder length divided by annular gap, H) are 10.1, 11.0, 12.6, 15.9, 22.5, 42.0. The angle of tilt annular cylinder from horizontal ({theta}, degree) is 0, 30, 45, 60 and 90 respectively. The temperature differences between inner wall and outer wall of the annulus are 10 to 120. The range of Rayleigh number is 7 {times} 10{sup 3} < Ra < 3 {times} 10{sup 7}. On the basis of analyzing and arranging a great deal of the experimental data and correcting overall heat transfer data for thermal radiation in the annulus, this paper presents the criterion equations Nu = f(Ra, K) for different tilt angles and the optimum annular gaps on different conditions for minimum heat losses. The experimental results are shown higher accuracy after comparing them with other literatures and repeating experiment verifications. They can be used directly in the design and appreciation for insulation properties of chemical industry equipment and oil pipeline.
Optimum dimensions of power solenoids for magnetic suspension
NASA Technical Reports Server (NTRS)
Kaznacheyev, B. A.
1985-01-01
Design optimization of power solenoids for controllable and stabilizable magnetic suspensions with force compensation in a wind tunnel is shown. It is assumed that the model of a levitating body is a sphere of ferromagnetic material with constant magnetic permeability. This sphere, with a radius much smaller than its distance from the solenoid above, is to be maintained in position on the solenoid axis by balance of the vertical electromagnetic force and the force of gravitation. The necessary vertical (axial) force generated by the solenoid is expressed as a function of relevant system dimensions, solenoid design parameters, and physical properties of the body. Three families of curves are obtained which depict the solenoid power for a given force as a function of the solenoid length with either outside radius or inside radius as a variable parameter and as a function of the outside radius with inside radius as a variable parameter. The curves indicate the optimum solenoid length and outside radius, for minimum power, corresponding to a given outside radius and inside radius, respectively.
Loop-the-Loop: Bringing Theory into Practice
ERIC Educational Resources Information Center
Suwonjandee, N.; Asavapibhop, B.
2012-01-01
During the Thai high-school physics teacher training programme, we used an aluminum loop-the-loop system built by the Institute for the Promotion of Teaching Science and Technology (IPST) to demonstrate a circular motion and investigate the concept of the conservation of mechanical energy. There were 27 high-school teachers from three provinces,…
Constraining Light Colored Particles with Event Shapes
David E. Kaplan; Matthew D. Schwartz
2008-04-16
Using recently developed techniques for computing event shapes with Soft-Collinear Effective Theory, LEP event shape data is used to derive strong model-independent bounds on new colored particles. In the effective field theory computation, colored particles contribute in loops not only to the running of alpha_s but also to the running of hard, jet and soft functions. Moreover, the differential distribution in the effective theory explicitly probes many energy scales, so event shapes have strong sensitivity to new particle thresholds. Using thrust data from ALEPH and OPAL, colored adjoint fermions (such as a gluino) below 51.0 GeV are ruled out to 95% confidence level. This is nearly an order-of-magnitude improvement over the previous model-independent bound of 6.3 GeV.
Shape Dynamics and Effective Field Theory
NASA Astrophysics Data System (ADS)
Koslowski, Tim A.
2013-05-01
Shape dynamics is a gauge theory based on spatial diffeomorphism- and Weyl-invariance which is locally indistinguishable from classical general relativity. If taken seriously, it suggests that the space-time geometry picture that underlies general relativity can be replaced by a picture based on spatial conformal geometry. This classically well-understood trading of gauge symmetries opens new conceptual avenues in many approaches to quantum gravity. This paper focusses on the general implications for quantum gravity and effective field theory and considers the application of the shape dynamics picture in the exact renormalization group approaches to gravity, loop- and polymer-quantization approaches to gravity and low energy effective field theories. Also, the interpretation of known results is discussed through the shape dynamics picture, particularly holographic renormalization and the problem of time in canonical quantum gravity.
Wilson loops T-dual to Short Strings
M. Kruczenski; A. A. Tseytlin
2013-01-21
We show that closed string solutions in the bulk of AdS space are related by T-duality to solutions representing an open string ending at the boundary of AdS. By combining the limit in which a closed string becomes small with a large boost, we find that the near-flat space short string in the bulk maps to a periodic open string world surface ending on a wavy line at the boundary. This open string solution was previously found by Mikhailov and corresponds to a time-like near BPS Wilson loop differing by small fluctuations from a straight line. A simple relation is found between the shape of the Wilson loop and the shape of the closed string at the moment when it crosses the horizon of the Poincare patch. As a result, the energy and spin of the closed string are encoded in properties of the Wilson loop. This suggests that closed string amplitudes with one of the closed strings falling into the Poincare horizon should be dual to gauge theory correlators involving local operators and a Wilson loop of the T-dual ("momentum") theory.
Black Hole Entropy, Loop Gravity, and Polymer Physics
Eugenio Bianchi
2010-11-25
Loop Gravity provides a microscopic derivation of Black Hole entropy. In this paper, I show that the microstates counted admit a semiclassical description in terms of shapes of a tessellated horizon. The counting of microstates and the computation of the entropy can be done via a mapping to an equivalent statistical mechanical problem: the counting of conformations of a closed polymer chain. This correspondence suggests a number of intriguing relations between the thermodynamics of Black Holes and the physics of polymers.
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.
Chesi, Stefano; CEMS, RIKEN, Wako, Saitama 351-0198 ; Jaffe, Arthur; Department of Physics, University of Basel, Basel; Institute for Theoretical Physics, ETH Zürich, Zürich ; Loss, Daniel; Department of Physics, University of Basel, Basel ; Pedrocchi, Fabio L.
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.
The Projectile Inside the Loop
ERIC Educational Resources Information Center
Varieschi, Gabriele U.
2006-01-01
The loop-the-loop demonstration can be easily adapted to study the kinematics of projectile motion, when the moving body falls inside the apparatus. Video capturing software can be used to reveal peculiar geometrical effects of this simple but educational experiment.
Sodium loop framework structural analysis
Nguyen, P.M.
1995-06-06
This document provides the structural analysis of the Sodium Loop framework in a drop condition. The drop is similar to the US Department of Transportation non-bulk, performance-oriented packaging (Packaging Group I) drop test. The drop height evaluated for the Sodium Loop framework is 5.9 ft.
Loop Heat Pipe for Electronics
Lee, Ho Sung
Loop Heat Pipe for Electronics Dr. HoSung Lee April 15, 2015 #12;Fujitsu Laboratories Ltd. Figure 1 the development of the world's first thin cooling device designed for small, thin electronic devices. Smartphones the world's first loop heat pipe less than 1 millimeter thick that can be added to small, thin electronics
Alexander V. Smirnov; Vladimir A. Smirnov; Matthias Steinhauser
2010-04-12
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 the fermion corrections of Ref. \\cite{Smirnov:2008pn} the complete answer at three loops.
MHD phenomena with AC loop voltages in RFP plasmas
NASA Astrophysics Data System (ADS)
McCollam, K. J.; Almagri, A. F.; Holly, D. J.; Sarff, J. S.; Stone, D. R.; Triana, J. C.
2011-10-01
The plasma's MHD response is an important aspect of experiments with applied AC loop voltages. For example, when oscillating-field current drive (OFCD), a type of helicity injection entailing phased AC poloidal and toroidal loop voltages, is applied to RFPs in the MST device with an empirically optimum phase of ~ ? / 8 between the two voltages, there is a decrease in magnetic-fluctuation amplitudes. By contrast, for ? / 2 , which is the phase of maximum helicity injection, additional bursts of magnetic fluctuations are induced, which internal measurements suggest are a linear MHD tearing response to the applied fields. Meanwhile, the AC loop voltages can entrain the normally quasiperiodic background sawtooth cycle in the RFP, triggering these discrete relaxation events to occur only at characteristic times within the OFCD cycle. This effect may involve criteria on the core safety factor and is investigated by equilibrium reconstructions of experiments in which AC fields of different frequencies and amplitudes are applied with a new programmable power supply. Finally, using internal probes, we plan to study the radial penetration of broadband AC fields from the switching of the solid-state programmable supply for possible effects on relaxation and current-profile control. This work is supported by the US DOE.
Optimum place of piezoelectric material in the piezoactuator design
NASA Astrophysics Data System (ADS)
Carbonari, Ronny C.; Nishiwaki, Shinji; Silva, Emílio C. N.
2006-03-01
Piezoelectric actuators offer significant promise in a wide range of applications. The piezoelectric actuators considered in this work essentially consist of a flexible structure actuated by piezoceramics that must generate output displacement and force at a certain specified point of the domain and direction. The flexible structure acts as a mechanical transformer by amplifying and changing the direction of piezoceramics output displacements. The design of these piezoelectric actuators are complex and a systematic design method, such as topology optimization has been successfully applied in the latest years, with appropriate formulation of the optimization problem to obtain optimized designs. However, in these previous design formulations, piezoceramics position are usually kept fixed in the design domain and only the flexible structure is designed by distributing only some non-piezoelectric material (Aluminum, for example). This imposes a constraint in the position of piezoelectric material in the optimization problem limiting the optimality of the solution. Thus, in this work, a formulation that allows the simultaneous search for an optimal topology of a flexible structure as well as the optimal positions of the piezoceramics in the design domain, to achieve certain specified actuation movements, will be presented. This can be achieved by allowing the simultaneous distribution of non-piezoelectric and piezoelectric material in the design domain. The optimization problem is posed as the design of a flexible structure together with optimum positions of piezoelectric material that maximizes output displacements or output forces in a certain specified direction and point of the domain. The method is implemented based on the SIMP material model where fictitious densities are interpolated in each finite element, providing a continuum material distribution in the domain. Presented examples are limited to two-dimensional models, once most of the applications for such piezoelectric actuators are planar devices.
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.
A theoretical analysis of optimum consumer population and its control.
Jiang, Z; Mao, Z; Wang, H
1994-01-01
Material production is related to population consumption in every society. Consumption also constantly transforms materials, energy, and information. In this sense, consumption provides both impetus for material production and a self-adapting mechanism for population development and control. Population structure variables affecting economic production can be divided according to non-adults, working-age work force and the elderly, social status, and urban-rural structure. The consumptive structures among people of different social status reflect different needs for social and economic development. The theoretical calculation of the consumer population in the national economy demonstrates that the national income in a certain year of a given national economy equals consumption fund plus accumulation fund where consumption fund includes social consumption fund and residential consumption fund. Social consumption fund is spent mostly on public utilities, administrative management, national defense, education, public health and urban construction, as well as on environment management and disaster relief. The residential consumption fund can be divided into basic expenditure such as clothing, food, shelter and transportation, and self-improvement expenditure such as recreation, education, and travel. As a result of economic development, not only the percentage of the expenditure on food will decrease and the percentage of the expenditure on clothing, shelter, transportation, and other daily necessities will increase, but expenses on recreation and education also will grow. Residential consumption is divided into subsistence consumption (Type I consumption) and self-improvement (recreation and education) consumption (Type II consumption) in order to determine consumer population and the degree of urbanization and its impact upon social and economic development. A moderate consumer population model of urban and rural areas was established by using the urban and rural consumption structure elasticity. This model was used in the correlation analysis of the coordinated healthy development of optimum consumer population and the economy. PMID:12288173
Widespread formation of cherts during the early Eocene climate optimum
NASA Astrophysics Data System (ADS)
Muttoni, G.; Kent, D. V.
2007-12-01
Radiolarian cherts in the Tethyan realm of Jurassic age were recently interpreted as resulting from high biosiliceous productivity along upwelling zones in subequatorial paleolatitudes the locations of which were confirmed by revised paleomagnetic estimates. However, the widespread occurrence of cherts in the Eocene suggests that cherts may not always be reliable proxies of latitude and upwelling zones. In a new survey of the global spatiotemporal distribution of Cenozoic cherts in Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) sediment cores, we found that cherts occur most frequently in the Paleocene and early Eocene, with a peak in occurrences at ~50 Ma that is coincident with the time of highest bottom water temperatures of the early Eocene climatic optimum (EECO) when the global ocean was presumably characterized by reduced upwelling efficiency and biosiliceous productivity. Cherts occur less commonly during the subsequent Eocene global cooling trend. Primary paleoclimatic factors rather than secondary diagenetic processes seem therefore to control chert formation. This timing of peak Eocene chert occurrence, which is supported by detailed stratigraphic correlations, contradicts currently accepted models that involve an initial loading of large amounts of dissolved silica from enhanced weathering and/or volcanism in a supposedly sluggish ocean of the EECO, followed during the subsequent middle Eocene global cooling by more vigorous oceanic circulation and consequent upwelling that made this silica reservoir available for enhanced biosilicification, with the formation of chert as a result of biosilica transformation during diagenesis. Instead, we suggest that basin-basin fractionation by deep-sea circulation could have raised the concentration of EECO dissolved silica especially in the North Atlantic, where an alternative mode of silica burial involving widespread direct precipitation and/or absorption of silica by clay minerals could have been operative in order to maintain balance between silica input and output during the upwelling-deficient conditions of the EECO. Cherts may therefore not always be proxies of biosiliceous productivity associated with latitudinally focused upwelling zones.
Arbitrary Dimensional Loop Quantum Cosmology
Xiangdong Zhang
2015-09-23
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. Our model serves as a first example of higher dimensional loop quantum cosmology and offers possibility to investigate quantum gravity effects in higher dimensional cosmology.
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.
Loop Heat Pipe Startup Behaviors
NASA Technical Reports Server (NTRS)
Ku, Jentung
2014-01-01
A loop heat pipe must start successfully before it can commence its service. The start-up transient represents one of the most complex phenomena in the loop heat pipe operation. This paper discusses various aspects of loop heat pipe start-up behaviors. Topics include the four start-up scenarios, the initial fluid distribution between the evaporator and reservoir that determines the start-up scenario, factors that affect the fluid distribution between the evaporator and reservoir, difficulties encountered during the low power start-up, and methods to enhance the start-up success. Also addressed are the thermodynamic constraint between the evaporator and reservoir in the loop heat pipe operation, the superheat requirement for nucleate boiling, pressure spike and pressure surge during the start-up transient, and repeated cycles of loop start-up andshutdown under certain conditions.
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.
A tunneling picture of dual giant Wilson loop
Akitsugu Miwa; Yoske Sumitomo; Kentaroh Yoshida
2008-02-28
We further discuss a rotating dual giant Wilson loop (D3-brane) solution constructed in Lorentzian AdS by Drukker et al. The solution is shown to be composed of a dual giant Wilson loop and a dual giant graviton by minutely examining its shape. This observation suggests that the corresponding gauge-theory operator should be a k-th symmetric Wilson loop with the insertions of dual giant graviton operators. To support the correspondence, the classical action of the solution should be computed and compared with the gauge-theory result. For this purpose we first perform a Wick rotation to the Lorentzian solution by following the tunneling prescription and obtain Euclidean solutions corresponding to a circular or a straight-line Wilson loop. In Euclidean signature boundary terms can be properly considered in the standard manner and the classical action for the Euclidean solutions can be evaluated. The result indeed reproduces the expectation value of the k-th symmetric Wilson loop as well as the power-law behavior of the correlation function of dual giant graviton operators.
Jameson, Antony
and turbomachinery blades operate in unsteady flow and are constantly subjected to unsteady loads. Therefore, optimal and turbomachinery and to alleviate the unsteady effects that contribute to flutter, buffeting, poor gust
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.
THE EFFECT OF RECEIVER DIVERSITY COMBINING ON OPTIMUM ENERGY ALLOCATION AND ENERGY EFFICIENCY
Brown III, Donald R.
THE EFFECT OF RECEIVER DIVERSITY COMBINING ON OPTIMUM ENERGY ALLOCATION AND ENERGY EFFICIENCY the total energy · Effect of diversity combining techniques on energy efficiency and energy allocation information yr1 = |h|asx + wr1 Scenario Problem Statement · Optimum energy allocation strategy to minimize
The Effect of Channel State Information on Optimum Energy Allocation and Energy Efficiency
Brown III, Donald R.
The Effect of Channel State Information on Optimum Energy Allocation and Energy Efficiency-- This paper considers the problem of how to efficiently allocate transmission energy in a wire- less. The analysis focuses on optimum energy allocation and energy efficiency for two distinctly different scenarios
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.
A SEARCH FOR THE OPTIMUM IMAGE DATABASE FOR HANDLING THE ORTHO-TEXTURES IN VRML
Çöltekin, Arzu
A SEARCH FOR THE OPTIMUM IMAGE DATABASE FOR HANDLING THE ORTHO-TEXTURES IN VRML Arzu Çöltekin M the methodology in searching an optimum image-database design suiting the purpose of this work. INTRODUCTION and the viewpoint changes. Therefore the number of the images that are stored, utilized and re-utilized is rather
ELSEVIER Marine Geology 153 (1999) 5775 Holocene Climate Optimum and Last Glacial Maximum in the
Rohling, Eelco
1999-01-01
ELSEVIER Marine Geology 153 (1999) 5775 Holocene Climate Optimum and Last Glacial Maximum surface waters between the Holocene Climate Optimum and the Present, and between the Last Glacial MaximumE oxygen isotope gradient during the Last Glacial Maximum, relative to the Present. This difference
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
Performance Analysis of Adaptive Modulation with Optimum Power Control in Cellular Systems
Chockalingam, A.
on fading channels have been derived in [5]. Adaptive modulation has been shown to yield significant im,and Adaptive Modulation with optimum Po- wer Control (AMPC). In this paper, we derivethe performance of the contribution is our proposal of two objectivefunctions,namely, Maximin-SIR optimum Power Control (MSPC
MAGNETIC RECONNECTION BETWEEN SMALL-SCALE LOOPS OBSERVED WITH THE NEW VACUUM SOLAR TELESCOPE
Yang, Shuhong; Zhang, Jun [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Xiang, Yongyuan, E-mail: shuhongyang@nao.cas.cn [Fuxian Solar Observatory, Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China)
2015-01-01
Using the high tempo-spatial resolution H? images observed with the New Vacuum Solar Telescope, we report solid observational evidence of magnetic reconnection between two sets of small-scale, anti-parallel loops with an X-shaped topology. The reconnection process contains two steps: a slow step with a duration of more than several tens of minutes, and a rapid step lasting for only about three minutes. During the slow reconnection, two sets of anti-parallel loops gradually reconnect, and new loops are formed and stacked together. During the rapid reconnection, the anti-parallel loops approach each other quickly, and then rapid reconnection takes place, resulting in the disappearance of the former loops. In the meantime, new loops are formed and separate. The region between the approaching loops is brightened, and the thickness and length of this region are determined to be about 420 km and 1.4 Mm, respectively. During the rapid reconnection process, obvious brightenings at the reconnection site and apparent material ejections outward along reconnected loops are observed. These observed signatures are consistent with predictions by reconnection models. We suggest that the successive slow reconnection changes the conditions around the reconnection site and triggers instabilities, thus leading to the rapid approach of the anti-parallel loops and resulting in the rapid reconnection.
Generation of rectangular prismatic dislocation loops in shells and cores of composite nanoparticles
NASA Astrophysics Data System (ADS)
Gutkin, M. Yu.; Smirnov, A. M.
2014-04-01
A theoretical model has been proposed for describing the relaxation of misfit stresses in a spherically symmetric composite core-shell nanoparticle due to the generation and expansion of rectangular prismatic dislocation loops at the internal and external interfaces. The critical conditions of the formation of these loops have been calculated for nanoparticles consisting of a relatively massive core and a thin shell. It has been shown that the generation of dislocation loops is possible when the misfit of the lattice parameters of the core and shell of the nanoparticle exceeds a critical value that depends on the nanoparticle radius, the shell thickness, the loop formation position, and the shape of loops. This condition holds for a loop in the shell when the shell thickness either lies in a specific range of small values or (for a larger misfit) is less than a critical value. For the generation of loops in the core, the shell thickness should exceed a critical value. The dislocation loops elongated along the core-shell interface are formed more readily. As the shell thickness increases at a fixed nanoparticle radius, the energetically more favorable generation of a dislocation loop occurs first from the free surface into the bulk of the shell, then from the interface into the shell, and finally from the interface into the core of the nanoparticle.
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.
Optimized input shaping for a single flexible robot link
Wilson, D.G.; Stokes, D.; Starr, G.; Robinett, R.D.
1996-03-01
This paper will discuss the design of an input shaped open-loop control for a single flexible robot link. The authors develop the equations of motion, including the first flexible mode shape and the actuator dynamics. Additional content includes the hardware system identification iterative runs used to update the model. Optimized input shaped commands for the flexible robot link to produce a rest-to-rest, residual vibration-free, 90 degree maneuver are developed. Correlation between both experimental and analytical results of the 90{degree} slew, using two different identification models, are reviewed.
Stability and bifurcation of a soap film spanning an elastic loop
Yi-chao Chen; Eliot Fried
2013-07-12
The Euler--Plateau problem, proposed by \\cite{gm}, concerns a soap film spanning a flexible loop. The shapes of the film and the loop are determined by the interactions between the two components. In the present work, the Euler--Plateau problem is reformulated to yield a boundary-value problem for a vector field that parameterizes both the spanning surface and the bounding loop. Using the first and second variations of the relevant free-energy functional, detailed bifurcation and stability analyses are performed. For spanning surface with energy density $\\sigma$ and a bounding loop with length $2\\pi R$ and bending rigidity $a$, the first bifurcation, during which the spanning surface remains flat but the bounding loop becomes noncircular, occurs at $\\sigma R^3/a=3$, confirming a result obtained previously via an energy comparison. Other bifurcation solution branches, including those emanating from the flat circular solution branch to nonplanar solution branches, are also shown to be unstable.
Design, fabrication and delivery of an improved single Elastic Loop Mobility System (ELMS)
NASA Technical Reports Server (NTRS)
Trautwein, W.
1972-01-01
Several significant design improvements have been incorporated into the second-generation full-scale ELMS unit. A major improved design accomplishment was the increase of the load carrying capacity of elastic loops without severe weight or stress penalties. Redesign of the loop form and size, plus selection of a more advanced titanium alloy, resulted in performance characteristics representing a marked improvement over the first-generation unit. Another important design improvement was the shaping of the loop's footprint into a favorable form for uniform pressure distribution. Other improvements are associated with a more efficient drive torque transmission from the internal drive drums to the elastic loop which are expected to reduce the internal losses of the drive system. The new ELMS unit will be capable of being integrated, on a modularized basis, with a multi-loop articulated ELMS test vehicle as the next logical step in the development of the mobility concept.
NSDL National Science Digital Library
OMSI
2004-01-01
In this activity, early learners combine pre-cut recognizable shapes and their own abstract ideas to make representational pictures (e.g. houses, trees, shoes). This exploration of shape identification and transformation develops problem-solving skills. Use the provided open-ended questions to help learners communicate the processes they used to select shapes and colors as well as develop and practice a vocabulary of color and shapes.
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.
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.
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.
Unimodular loop quantum cosmology
Chiou, D.-W.; Geiller, Marc [Department of Physics, Beijing Normal University, Beijing 100875 (China); APC-Astroparticule et Cosmologie, Universite Paris Diderot Paris 7, Paris (France)
2010-09-15
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.
Closed loop obstruction: pictorial essay.
Mbengue, A; Ndiaye, A; Soko, T O; Sahnoun, M; Fall, A; Diouf, C T; Régent, D; Diakhaté, I C
2015-02-01
Closed loop obstruction occurs when a segment of bowel is incarcerated at two contiguous points. The diagnosis is based on multiple transitional zones. The incarcerated loops appear in U or C form or present a radial layout around the location of the obstruction. It's very important to specify the type of obstruction because, in patients with simple bowel obstruction, a conservative approach is often advised. On the other hand, a closed loop obstruction immediately requires a surgical approach because of its high morbidity and the risk of death in case of a late diagnosis. PMID:24290342
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.
Philip Shilane; Patrick Min; Michael M. Kazhdan; Thomas A. Funkhouser
2004-01-01
In recent years, many shape representations and geomet- ric algorithms have been proposed for matching 3D shapes. Usually, each algorithm is tested on a different (small) database of 3D models, and thus no direct comparison is available for competing methods. In this paper, we describe the Princeton Shape Bench- mark (PSB), a publicly available database of polygonal models collected from
ERIC Educational Resources Information Center
Albertazzi, Liliana; Da Pos, Osvaldo; Canal, Luisa; Micciolo, Rocco; Malfatti, Michela; Vescovi, Massimo
2013-01-01
This article presents an experimental study on the naturally biased association between shape and color. For each basic geometric shape studied, participants were asked to indicate the color perceived as most closely related to it, choosing from the Natural Color System Hue Circle. Results show that the choices of color for each shape were not…
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…
Application of digital pulse shaping by least squares method to ultrasonic signals in composites
NASA Technical Reports Server (NTRS)
Kishoni, D.
1985-01-01
For ultrasonic testing in composites, a signal processing tool is identified that can significantly enhance the sharpness of ultrasonic waveforms and provide clearer pictures of the nature of the material flaw. The technique artificially improves the resolution of the system to discrete events by pulse shaping the measured waveform based on the signal from a reference. The optimum pulse shape operator is determined from a least-squares method in the z-domain.
Affective loop experiences: designing for interactional embodiment
Höök, Kristina
2009-01-01
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
Loop Electrosurgical Excision Procedure (LEEP)
... that acts like a scalpel (surgical knife). An electric current is passed through the loop, which cuts ... A procedure in which an instrument works with electric current to destroy tissue. Local Anesthesia: The use ...
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.
Arbitrary Dimensional Loop Quantum Cosmology
Xiangdong Zhang
2015-06-26
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.
Shape optimization of microlenses.
Paganini, A; Sargheini, S; Hiptmair, R; Hafner, Ch
2015-05-18
Microlenses are highly attractive for optical applications such as super resolution and photonic nanojets, but their design is more demanding than the one of larger lenses because resonance effects play an important role, which forces one to perform a full wave analysis. Although mostly spherical microlenses were studied in the past, they may have various shapes and their optimization is highly demanding, especially, when the shape is described with many parameters. We first outline a very powerful mathematical tool: shape optimization based on shape gradient computations. This procedure may be applied with much less numerical cost than traditional optimizers, especially when the number of parameters describing the shape goes to infinity. In order to demonstrate the concept, we optimize microlenses using shape optimization starting from more or less reasonable elliptical and semi-circular shapes. We show that strong increases of the performance of the lenses may be obtained for any reasonable value of the refraction index. PMID:26074562
General shape optimization capability
NASA Technical Reports Server (NTRS)
Chargin, Mladen K.; Raasch, Ingo; Bruns, Rudolf; Deuermeyer, Dawson
1991-01-01
A method is described for calculating shape sensitivities, within MSC/NASTRAN, in a simple manner without resort to external programs. The method uses natural design variables to define the shape changes in a given structure. Once the shape sensitivities are obtained, the shape optimization process is carried out in a manner similar to property optimization processes. The capability of this method is illustrated by two examples: the shape optimization of a cantilever beam with holes, loaded by a point load at the free end (with the shape of the holes and the thickness of the beam selected as the design variables), and the shape optimization of a connecting rod subjected to several different loading and boundary conditions.
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.
Neutrino Factory Mercury Flow Loop
McDonald, Kirk
Neutrino Factory Mercury Flow Loop V. GravesV. Graves C. Caldwell IDS-NF Videoconference March 9, 2010 #12;Flow Loop Review · 1 cm dia nozzle, 20 m/s jet requires 1.57 liter/sec mercury flow (94 2 liter/min 24 9 gpm)mercury flow (94.2 liter/min, 24.9 gpm). · MERIT experiment showed that a pump
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
Development of Non-Optimum Factors for Launch Vehicle Propellant Tank Bulkhead Weight Estimation
NASA Technical Reports Server (NTRS)
Wu, K. Chauncey; Wallace, Matthew L.; Cerro, Jeffrey A.
2012-01-01
Non-optimum factors are used during aerospace conceptual and preliminary design to account for the increased weights of as-built structures due to future manufacturing and design details. Use of higher-fidelity non-optimum factors in these early stages of vehicle design can result in more accurate predictions of a concept s actual weights and performance. To help achieve this objective, non-optimum factors are calculated for the aluminum-alloy gores that compose the ogive and ellipsoidal bulkheads of the Space Shuttle Super-Lightweight Tank propellant tanks. Minimum values for actual gore skin thicknesses and weld land dimensions are extracted from selected production drawings, and are used to predict reference gore weights. These actual skin thicknesses are also compared to skin thicknesses predicted using classical structural mechanics and tank proof-test pressures. Both coarse and refined weights models are developed for the gores. The coarse model is based on the proof pressure-sized skin thicknesses, and the refined model uses the actual gore skin thicknesses and design detail dimensions. To determine the gore non-optimum factors, these reference weights are then compared to flight hardware weights reported in a mass properties database. When manufacturing tolerance weight estimates are taken into account, the gore non-optimum factors computed using the coarse weights model range from 1.28 to 2.76, with an average non-optimum factor of 1.90. Application of the refined weights model yields non-optimum factors between 1.00 and 1.50, with an average non-optimum factor of 1.14. To demonstrate their use, these calculated non-optimum factors are used to predict heavier, more realistic gore weights for a proposed heavy-lift launch vehicle s propellant tank bulkheads. These results indicate that relatively simple models can be developed to better estimate the actual weights of large structures for future launch vehicles.
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.
The searching method of quasi-optimum group SYNC codes on the subset of PN sequences
NASA Astrophysics Data System (ADS)
Cao, Jie; Xie, Qiu-Cheng
This paper gives a searching method of quasi-optimum group sync codes on a small subset of PN sequences - cut-tail searching method and prefix-suffix searching method. Quasi-optimum group sync codes have been searched out for their lengths N = 32-63 by this method and they have been compared with corresponding optimum group sync codes for their lengths N = 32-54. The total searching time is only several seconds. This method may solve problems of error sync probability, code length, and searching time. Hence it is a good and practical searching method for long code.
Filter for third order phase locked loops
NASA Technical Reports Server (NTRS)
Crow, R. B.; Tausworthe, R. C. (inventors)
1973-01-01
Filters for third-order phase-locked loops are used in receivers to acquire and track carrier signals, particularly signals subject to high doppler-rate changes in frequency. A loop filter with an open-loop transfer function and set of loop constants, setting the damping factor equal to unity are provided.
Loop Leaping with Closures Sebastian Biallas1
Kent, University of
Loop Leaping with Closures Sebastian Biallas1 , J¨org Brauer1,2 , Andy King3,4 and Stefan of Kent, UK Abstract. Loop leaping is the colloquial name given to a form of program analysis in which-up fashion considering one more loop at a time. Loop leaping contrasts with classical approaches to finding
Jordan Loops Using Prover9/Mace4 to understand Jordan Loops
Veroff, Robert
there exist non-associative Jordan loops? Mace9 finds the following: None of order less than 6. Finds models to understand Jordan Loops #12;Jordan Loops Constructions We found constructions giving models of order nJordan Loops Using Prover9/Mace4 to understand Jordan Loops Kyle Pula June 22nd, 2007 Kyle Pula
A Noise-Shaped Switched-Capacitor DC-DC Voltage Regulator A. Rao, W.McIntyre 1
Moon, Un-Ku
reasons to choose capacitive DC/DC conversion over inductive are reduced electro- magnetic induction (EMI in the loop, and its output ripple is frequency shaped by the loop, which also provides the pulse- frequency a magnetic coil, the switched-capacitor system uses an array of switches and capacitors. Some of the primary
Kalman Orbit Optimized Loop Tracking
NASA Technical Reports Server (NTRS)
Young, Lawrence E.; Meehan, Thomas K.
2011-01-01
Under certain conditions of low signal power and/or high noise, there is insufficient signal to noise ratio (SNR) to close tracking loops with individual signals on orbiting Global Navigation Satellite System (GNSS) receivers. In addition, the processing power available from flight computers is not great enough to implement a conventional ultra-tight coupling tracking loop. This work provides a method to track GNSS signals at very low SNR without the penalty of requiring very high processor throughput to calculate the loop parameters. The Kalman Orbit-Optimized Loop (KOOL) tracking approach constitutes a filter with a dynamic model and using the aggregate of information from all tracked GNSS signals to close the tracking loop for each signal. For applications where there is not a good dynamic model, such as very low orbits where atmospheric drag models may not be adequate to achieve the required accuracy, aiding from an IMU (inertial measurement unit) or other sensor will be added. The KOOL approach is based on research JPL has done to allow signal recovery from weak and scintillating signals observed during the use of GPS signals for limb sounding of the Earth s atmosphere. That approach uses the onboard PVT (position, velocity, time) solution to generate predictions for the range, range rate, and acceleration of the low-SNR signal. The low- SNR signal data are captured by a directed open loop. KOOL builds on the previous open loop tracking by including feedback and observable generation from the weak-signal channels so that the MSR receiver will continue to track and provide PVT, range, and Doppler data, even when all channels have low SNR.
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.
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.
Scintillation and BER for optimum sinusoidal Gaussian beams in weak non-Kolmogorov turbulence
NASA Astrophysics Data System (ADS)
Gerçekcio?lu, Hamza; Baykal, Yahya
2014-06-01
The scintillation index and the average bit error rate (BER) are evaluated for the optimum sinusoidal Gaussian beams in weak non-Kolmogorov turbulence. The beam parameters that minimize the scintillation index and the average BER are stated and such beams are denoted as the optimum beams. For the collimated Gaussian, cos- and cosh-Gaussian beams, the scintillations increase as the power law exponent, ? increases. Cos- and cosh-Gaussian beams that have larger absolute displacement parameters are found to exhibit larger scintillations especially at small ?. Larger focal length and larger source size of cos-Gaussian beams induce reduction in the scintillations. When the propagation distance is large, the power law exponent is small and the source size is large, the scintillations of the optimum beams tend to decrease. Small power law exponent and large source size reduce the average BER. The optimum beam is shown to exhibit the smallest average BER for any ?.
Shinji Suzuki; Yonezawa Satoshi
1990-01-01
Equations for the optimum structural design of a cantilevered rectangular wing are presented. The Liapunov method is applied and the targets of the optimization are discussed. The structural optimization is analyzed.
Performance Analysis of V-BLAST with Optimum Power Victoria Kostina, Sergey Loyka
Loyka, Sergey
Performance Analysis of V-BLAST with Optimum Power Allocation Victoria Kostina, Sergey Loyka School-mail: sergey.loyka@ieee.org Abstract--Comprehensive performance analysis of the unordered V-BLAST algorithm
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
Aerodynamic Shape Optimization Using Hybridized Differential Evolution
NASA Technical Reports Server (NTRS)
Madavan, Nateri K.
2003-01-01
An aerodynamic shape optimization method that uses an evolutionary algorithm known at Differential Evolution (DE) in conjunction with various hybridization strategies is described. DE is a simple and robust evolutionary strategy that has been proven effective in determining the global optimum for several difficult optimization problems. Various hybridization strategies for DE are explored, including the use of neural networks as well as traditional local search methods. A Navier-Stokes solver is used to evaluate the various intermediate designs and provide inputs to the hybrid DE optimizer. The method is implemented on distributed parallel computers so that new designs can be obtained within reasonable turnaround times. Results are presented for the inverse design of a turbine airfoil from a modern jet engine. (The final paper will include at least one other aerodynamic design application). The capability of the method to search large design spaces and obtain the optimal airfoils in an automatic fashion is demonstrated.
Improved peak shape fitting in alpha spectra.
Pommé, S; Caro Marroyo, B
2015-02-01
Peak overlap is a recurrent issue in alpha-particle spectrometry, not only in routine analyses but also in the high-resolution spectra from which reference values for alpha emission probabilities are derived. In this work, improved peak shape formulae are presented for the deconvolution of alpha-particle spectra. They have been implemented as fit functions in a spreadsheet application and optimum fit parameters were searched with built-in optimisation routines. Deconvolution results are shown for a few challenging spectra with high statistical precision. The algorithm outperforms the best available routines for high-resolution spectrometry, which may facilitate a more reliable determination of alpha emission probabilities in the future. It is also applicable to alpha spectra with inferior energy resolution. PMID:25497323
Automated Coronal Loop Identification Using Digital Image Processing Techniques
NASA Technical Reports Server (NTRS)
Lee, Jong K.; Gary, G. Allen; Newman, Timothy S.
2003-01-01
The results of a master thesis project on a study of computer algorithms for automatic identification of optical-thin, 3-dimensional solar coronal loop centers from extreme ultraviolet and X-ray 2-dimensional images will be presented. These center splines are proxies of associated magnetic field lines. The project is pattern recognition problems in which there are no unique shapes or edges and in which photon and detector noise heavily influence the images. The study explores extraction techniques using: (1) linear feature recognition of local patterns (related to the inertia-tensor concept), (2) parametric space via the Hough transform, and (3) topological adaptive contours (snakes) that constrains curvature and continuity as possible candidates for digital loop detection schemes. We have developed synthesized images for the coronal loops to test the various loop identification algorithms. Since the topology of these solar features is dominated by the magnetic field structure, a first-order magnetic field approximation using multiple dipoles provides a priori information in the identification process. Results from both synthesized and solar images will be presented.
Optimum Projection Angle for Attaining Maximum Distance in a Rugby Place Kick
Linthorne, Nicholas P.; Stokes, Thomas G.
2014-01-01
This study investigated the effect of projection angle on the distance attained in a rugby place kick. A male rugby player performed 49 maximum-effort kicks using projection angles of between 20 and 50°. The kicks were recorded by a video camera at 50 Hz and a 2 D biomechanical analysis was conducted to obtain measures of the projection velocity and projection angle of the ball. The player’s optimum projection angle was calculated by substituting a mathematical expression for the relationship between projection velocity and projection angle into the equations for the aerodynamic flight of a rugby ball. We found that the player’s calculated optimum projection angle (30.6°, 95% confidence limits ± 1.9°) was in close agreement with his preferred projection angle (mean value 30.8°, 95% confidence limits ± 2.1°). The player’s calculated optimum projection angle was also similar to projection angles previously reported for skilled rugby players. The optimum projection angle in a rugby place kick is considerably less than 45° because the projection velocity that a player can produce decreases substantially as projection angle is increased. Aerodynamic forces and the requirement to clear the crossbar have little effect on the optimum projection angle. Key Points The optimum projection angle in a rugby place kick is about 30°. The optimum projection angle is considerably less than 45° because the projection velocity that a player can produce decreases substantially as projection angle is increased. Aerodynamic forces and the requirement to clear the crossbar have little effect on the optimum projection angle. PMID:24570626
Iterative construction of optimum signature sequence sets in synchronous CDMA systems
Sennur Ulukus; Roy D. Yates
2001-01-01
Recently, optimum signature sequence sets that maximize the capacity of single cell synchronousCDMA systems have been identified. Optimum signature sequences minimize theTotal Squared Correlation (TSC); they form a set of orthogonal sequences, if the number ofusers is less than or equal to the processing gain, and a set of WBE sequences, otherwise.We present an algorithm where users update their transmitter
Creating the feedback loop: closed-loop neurostimulation.
Hebb, Adam O; Zhang, Jun Jason; Mahoor, Mohammad H; Tsiokos, Christos; Matlack, Charles; Chizeck, Howard Jay; Pouratian, Nader
2014-01-01
Current DBS therapy delivers a train of electrical pulses at set stimulation parameters. This open-loop design is effective for movement disorders, but therapy may be further optimized by a closed loop design. The technology to record biosignals has outpaced our understanding of their relationship to the clinical state of the whole person. Neuronal oscillations may represent or facilitate the cooperative functioning of brain ensembles, and may provide critical information to customize neuromodulation therapy. This review addresses advances to date, not of the technology per se, but of the strategies to apply neuronal signals to trigger or modulate stimulation systems. PMID:24262909
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.
NASA Astrophysics Data System (ADS)
Zhao, Yong; Chen, Genliang; Wang, Hao; Lin, Zhongqin
2013-07-01
The mechanism type plays a decisive role in the mechanical performance of robotic manipulators. Feasible mechanism types can be obtained by applying appropriate type synthesis theory, but there is still a lack of effective and efficient methods for the optimum selection among different types of mechanism candidates. This paper presents a new strategy for the purpose of optimum mechanism type selection based on the modified particle swarm optimization method. The concept of sub-swarm is introduced to represent the different mechanisms generated by the type synthesis, and a competitive mechanism is employed between the sub-swarms to reassign their population size according to the relative performances of the mechanism candidates to implement the optimization. Combining with a modular modeling approach for fast calculation of the performance index of the potential candidates, the proposed method is applied to determine the optimum mechanism type among the potential candidates for the desired manipulator. The effectiveness and efficiency of the proposed method is demonstrated through a case study on the optimum selection of mechanism type of a heavy manipulator where six feasible candidates are considered with force capability as the specific performance index. The optimization result shows that the fitness of the optimum mechanism type for the considered heavy manipulator can be up to 0.578 5. This research provides the instruction in optimum selection of mechanism types for robotic manipulators.
Griffiths, S.K.; Nilson, R.H.
1996-06-01
A second-order perturbation solution describing the radial transport of a reactive species and concurrent deposition on wafer surfaces is derived for use in optimizing CVD process conditions. The result is applicable to a variety of deposition reactions and accounts for both diffusive and advective transport, as well as both ordinary and Knudsen diffusion. Based on the first-order approximation, the deposition rate is maximized subject to a constraint on the radial uniformity of the deposition rate. For a fixed reactant mole fraction, the optimum pressure and optimum temperature are obtained using the method of Lagrange multipliers. This yields a weak one-sided maximum; deposition rates fall as pressures are reduced but remain nearly constant at all pressures above the optimum value. The deposition rate is also maximized subject to dual constraints on the uniformity and particle nucleation rate. In this case, the optimum pressure, optimum temperature and optimum reactant fraction are similarly obtained, and the resulting maximum deposition rate is well defined. These results are also applicable to CVI processes used in composites manufacturing.
Towards the optimum gas-assisted liquid atomizer configuration
NASA Astrophysics Data System (ADS)
Ganan-Calvo, Alfonso M.
2002-11-01
Although this has been an ancient subject of Fluid Mechanics with a vast literature on it, in this work we present a thoroughout experimental analysis of simple axisymmetric co-flowing gas-assisted liquid atomizers. In this work we have made a systematic search for significant and reproducible "excellent" or "optimal" configurations which minimize both the main droplet size, the droplet size dispersity, and the energy budget necessary to achieve, in particular, 85 percent liquid mass atomization in sizes below a certain given goal (in particular, respirable -micrometric- droplet sizes) for a given liquid flow rate. We have experimentally explored and analyzed the effect of (i) the relative size of the three main geometrical parameters (v.g. the main exit orifice diameter, the liquid feeding tube external diameter, and the distance between the plane of the exit orifice and the plane of the tube mouth), and (ii) the absolute dimensions of the atomizer. To tackle this phenomenal goal, here we propose a systematic approach to sweep the geometrical parameter space, which obviously must consider the physics of (i) the initial interaction and momentum transfer between liquid and gas as well as the gas "shaping" force on the liquid stream, (ii) the gas jet configuration at the orifice exit as well as the different developing regions of the liquid bulk breakup, and (iii) the droplet size distribution development up to the final "relaxed" state. Along the search through the landscaping of the geometrical parameter space, we have consistently found a family of simple "excellent" axisymmetric configurations (that could be proved "optimal" for manufacturing -with no "small features"-, and in microfluidics) previously unexplored, where the spray droplet size can be very significantly smaller, in some cases more than one order of magnitude smaller than "classical" well established "best" configurations, for the same liquid flow rate and energy budget. In particular, we show the universal scaling laws which characterize this family and how these laws asymptotically and consistently reproduce the scaling laws of other atomization classical schemes like the simple plain-jet circular orifice atomizer.
Decentralized Control of Sound Radiation Using Iterative Loop Recovery
NASA Technical Reports Server (NTRS)
Schiller, Noah H.; Cabell, Randolph H.; Fuller, Chris R.
2009-01-01
A decentralized model-based control strategy is designed to reduce low-frequency sound radiation from periodically stiffened panels. While decentralized control systems tend to be scalable, performance can be limited due to modeling error introduced by the unmodeled interaction between neighboring control units. Since bounds on modeling error are not known in advance, it is difficult to ensure the decentralized control system will be robust without making the controller overly conservative. Therefore an iterative approach is suggested, which utilizes frequency-shaped loop recovery. The approach accounts for modeling error introduced by neighboring control loops, requires no communication between subsystems, and is relatively simple. The control strategy is evaluated numerically using a model of a stiffened aluminum panel that is representative of the sidewall of an aircraft. Simulations demonstrate that the iterative approach can achieve significant reductions in radiated sound power from the stiffened panel without destabilizing neighboring control units.
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.
Thermodynamics in Loop Quantum Cosmology
Li-Fang Li; Jian-Yang Zhu
2008-12-18
Loop quantum cosmology (LQC) is very powerful to deal with the behavior of early universe. And the effective loop quantum cosmology gives a successful description of the universe in the semiclassical region. We consider the apparent horizon of the Friedmann-Robertson-Walker universe as a thermodynamical system and investigate the thermodynamics of LQC in the semiclassical region. The effective density and effective pressure in the modified Friedmann equation from LQC not only determine the evolution of the universe in LQC scenario but are actually also found to be the thermodynamic quantities. This result comes from the energy definition in cosmology (the Misner-Sharp gravitational energy) and is consistent with thermodynamic laws. We prove that within the framework of loop quantum cosmology, the elementary equation of equilibrium thermodynamics is still valid.
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.
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
Observing the Reconnection Region in A Transequatorial Loop , Tongjiang Wang2
legs approached each other, plasma flew at 6 km s-1 into a local area where a cusp-shaped flare loop, a clear signature of chromospheric evaporation was seen during the decay phase, i.e., the cusp--Sun: flares--Sun: Corona 1. Introduction Magnetic energy is the only viable energy source to power
ERIC Educational Resources Information Center
Alterovitz, Gil
2004-01-01
This research analyzed both engineering and nontechnical issues involved in the use of Induction Loop Amplification (ILA) devices in auditoriums or large gathering places for hard-of-hearing individuals. A variety of parameters need to be taken into account to determine an optimal shape/configuration for the ILA device. In many cases, an optimal…
NSDL National Science Digital Library
2011-05-19
In this activity students ask yes-or-no questions to identify an object based on its geometric shape. Players can not ask if it is a specific object. The activity helps students to develop logic and reasoning skills as well as recognition of shapes.
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,
NSDL National Science Digital Library
2011-01-01
This Java applet allows children to explore a balancing tool and thus build their algebraic thinking about equivalency. By placing shapes on each side of the balance and finding equivalent sets of weights, students discover the weight of each shape in one of six built-in sets or a random set.
Shape Matching Michael Kazhdan
Kazhdan, Michael
Shape Matching Michael Kazhdan (600.357 / 600.457) #12;Overview · Intro · General Approach · General Approach · Minimum SSD Descriptor #12;Shape Matching General approach: Define a function Retrieval · Return the closest matches Best Match 3D Query Database Models Sorted Models D(Q,Mi) Q M1 M2 Mn
Loop Quantum Cosmology: An Overview
Abhay Ashtekar
2008-11-30
A brief overview of loop quantum cosmology of homogeneous isotropic models is presented with emphasis on the origin of and subtleties associated with the resolution of big bang and big crunch singularities. These results bear out the remarkable intuition that John Wheeler had. Discussion is organized at two levels. The the main text provides a bird's eye view of the subject that should be accessible to non-experts. Appendices address conceptual and technical issues that are often raised by experts in loop quantum gravity and string theory.
Loop Quantum Cosmology: An Overview
Ashtekar, Abhay
2008-01-01
A brief overview of loop quantum cosmology of homogeneous isotropic models is presented with emphasis on the origin of and subtleties associated with the resolution of big bang and big crunch singularities. These results bear out the remarkable intuition that John Wheeler had. Discussion is organized at two levels. The the main text provides a bird's eye view of the subject that should be accessible to non-experts. Appendices address conceptual and technical issues that are often raised by experts in loop quantum gravity and string theory.
Perturbations in loop quantum cosmology
Ivan Agullo; Abhay Ashtekar; William Nelson
2012-04-05
The era of precision cosmology has allowed us to accurately determine many important cosmological parameters, in particular via the CMB. Confronting Loop Quantum Cosmology with these observations provides us with a powerful test of the theory. For this to be possible we need a detailed understanding of the generation and evolution of inhomogeneous perturbations during the early, Quantum Gravity, phase of the universe. Here we describe how Loop Quantum Cosmology provides a completion of the inflationary paradigm, that is consistent with the observed power spectra of the CMB.
Loop Variables in Topological Gravity
Y. Bi; J. Gegenberg
1993-07-22
We examine the relationship between covariant and canonical (Ashtekar/Rovelli/Smolin) loop variables in the context of BF type topological field theories in 2+1 and 3+1 dimensions, with respective gauge groups SO(2,1) and SO(3,1). The latter model can be considered as the simplest topological gravity theory in 3+1 dimensions. We carry out the canonical quantization of this model in both the connection and loop representations, for the two spatial topologies $T^3$ and $S^2\\times S^1$.
Skeldon, M.D.; Letzring, S.A.
1999-03-23
Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses. 8 figs.
Skeldon, Mark D. (Penfield, NY); Letzring, Samuel A. (Jemez Springs, NM)
1999-03-23
Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses.
Simulations of Gyrosynchrotron Microwave Emission from an Oscillating 3D Magnetic Loop
Kuznetsov, Alexey; Reznikova, Veronika
2015-01-01
Radio observations of solar flares often reveal various periodic or quasi-periodic oscillations. Most likely, these oscillations are caused by magnetohydrodynamic (MHD) oscillations of flaring loops which modulate the emission. Interpretation of the observations requires comparing them with simulations. We simulate the gyrosynchrotron radio emission from a semi-circular (toroidal-shaped) magnetic loop containing sausage-mode MHD oscillations. The aim is to detect the observable signatures specific to the considered MHD mode and to study their dependence on the various source parameters. The MHD waves are simulated using a linear three-dimensional model of a magnetized plasma cylinder; both standing and propagating waves are considered. The curved loop is formed by replicating the MHD solutions along the plasma cylinder and bending the cylinder; this model allows us to study the effect of varying the viewing angle along the loop. The radio emission is simulated using a three-dimensional model and its spatial a...
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
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.
Effect of the Potential Shape on the Stochastic Resonance Processes
NASA Astrophysics Data System (ADS)
Kenmoé, G. Djuidjé; Ngouongo, Y. J. Wadop; Kofané, T. C.
2015-07-01
The stochastic resonance (SR) induced by periodic signal and white noises in a periodic nonsinusoidal potential is investigated. This phenomenon is studied as a function of the friction coefficient as well as the shape of the potential. It is done through an investigation of the hysteresis loop area which is equivalent to the input energy lost by the system to the environment per period of the external force. SR is evident in some range of the shape parameter of the potential, but cannot be observed in the other range. Specially, variation of the shape potential affects significantly and not trivially the heigh of the potential barrier in the Kramers rate as well as the occurrence of SR. The finding results show crucial dependence of the temperature of occurrence of SR on the shape of the potential. It is noted that the maximum of the input energy generally decreases when the friction coefficient is increased.
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.
OUTER LOOP LANDFILL CASE STUDY
This presentation will describe the interim data reaulting from a CRADA between USEPA and Waste Management, Inc. at the outer Loop Landfill Bioreactor research project located in Louisville, KY. Recently updated data will be presented covering landfill solids, gas being collecte...
Instantons and BPS Wilson loops
Massimo Bianchi; Michael B. Green; Stefano Kovacs
2001-07-04
The one-instanton contribution to a circular BPS Wilson loop in N=4 SU(2) Yang--Mills theory is evaluated in semiclassical approximation. This article amplifies part of a talk given by MBG at the Strings 2001 conference, Mumbai, India (January 5-10, 2001). The results are preliminary and a more complete exposition will be contained in a forthcoming paper.
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.
Plasma heating in coronal loops
NASA Astrophysics Data System (ADS)
Luhmann, J. G.; Broussard, R. M.
1980-02-01
In the lower corona, where plasma is constrained to flow in the direction of the local magnetic field, a loop field geometry connecting regions of opposite polarity will force plasma originating at the two foot points of the arch-like flux tube to interact. If the tube has a cross section that increases with distance from a foot point, the plasma evaporating at the foot point can be accelerated along the field in the same fashion as the solar wind is accelerated along open diverging flux tubes. If this acceleration occurs symmetrically with respect to the apex of the loop, Coulomb collisions between the ions of the resulting two streams from the opposite foot point convert this direct energy to thermal energy. Since the flux tube converges at both ends and the Coulomb collisions cause pitch angle scattering as well as thermalization, the heated plasma accumulates. The loop is destroyed when the pressure of the trapped plasma becomes greater than the confining pressure. The feasibility of this model of coronal loops is assessed using an example observed with the X-ray telescope on Skylab.
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
Bazin-Lopez, Naiara; Valdivia, Leonardo E; Wilson, Stephen W; Gestri, Gaia
2015-06-01
Vertebrate eye formation is a multistep process requiring coordinated inductive interactions between neural and non-neural ectoderm and underlying mesendoderm. The induction and shaping of the eyes involves an elaborate cellular choreography characterized by precise changes in cell shape coupled with complex cellular and epithelial movements. Consequently, the forming eye is an excellent model to study the cellular mechanisms underlying complex tissue morphogenesis. Using examples largely drawn from recent studies of optic vesicle formation in zebrafish and in cultured embryonic stem cells, in this short review, we highlight some recent advances in our understanding of the events that shape the vertebrate eye. PMID:25748250
NSDL National Science Digital Library
2013-12-04
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.
NSDL National Science Digital Library
1997-01-01
This site, maintained by Shape Up America! and Infosector Corporation, offers visitors a great way to keep up on the latest developments in weight management and physical fitness. Surveys, public service announcements, press releases and more are available. First-time visitors can determine their Body Mass Index (BMI), a ratio between weight and height that correlates with body fat. Shape Up America! also has beneficial information for the heath professional. Shape Up America! is a non-profit corporation established by C. Everett Koop, M.D., the former US Surgeon General.
NSDL National Science Digital Library
TERC
2012-06-26
In this activity, learners make patterns consisting of words and shapes. Learners get sets of triangles, squares, and rectangles. Each shape contains a word. Learners arrange the shapes into a geometric pattern that repeats or changes in a systematic way on each line. Younger learners can create simple repeating patterns; older ones can explore patterns that grow in different ways. This activity comes with word sets in three levels of difficulty. Available as a web page and a downloadable PDF. Also available in Spanish.
Optimum Dynamic Characteristics of Stockbridge Dampers for Dead-End Spans
NASA Astrophysics Data System (ADS)
Markiewicz, M.
1995-11-01
Stockbridge dampers are commonly used to protect conductors of overhead transmission lines from aeolian vibrations. Standard Stockbridge dampers are designed so that their mechanical impedance matches as closely as possible the optimum damper impedance determined for the cable to be protected. Since the optimum impedance is evaluated assuming that the cable is clamped at its extremity, the optimally tuned standard dampers will work efficiently only when they are mounted near suspension clamps. In some spans, however, conductors are connected to the tower by means of special tension equipment which may influence the efficiency of the mounted standard damper. The present analysis shows that the optimum damper impedance required for such spans (called dead-end spans) differs significantly from the optimum impedance of the standard damper. The reason for this is the dynamic interaction between the tension insulator assembly and the damper itself. This interaction cannot be neglected for vibration frequencies which are close to the resonance frequencies of the tension insulator assembly. This paper presents a method and computational model for the evaluation of the optimum dynamic characteristics of Stockbridge dampers to be mounted near tension insulator assemblies. It also shows how the efficiency of a standard damper used in such spans may be improved by its proper location on a cable.
Steinhaus, Benjamin; Garcia, Marcelo L.; Shen, Amy Q.; Angenent, Largus T.
2007-01-01
Conventional studies of the optimum growth conditions for methanogens (methane-producing, obligate anaerobic archaea) are typically conducted with serum bottles or bioreactors. The use of microfluidics to culture methanogens allows direct microscopic observations of the time-integrated response of growth. Here, we developed a microbioreactor (?BR) with ?1-?l microchannels to study some optimum growth conditions for the methanogen Methanosaeta concilii. The ?BR is contained in an anaerobic chamber specifically designed to place it directly onto an inverted light microscope stage while maintaining a N2-CO2 environment. The methanogen was cultured for months inside microchannels of different widths. Channel width was manipulated to create various fluid velocities, allowing the direct study of the behavior and responses of M. concilii to various shear stresses and revealing an optimum shear level of ?20 to 35 ?Pa. Gradients in a single microchannel were then used to find an optimum pH level of 7.6 and an optimum total NH4-N concentration of less than 1,100 mg/liter (<47 mg/liter as free NH3-N) for M. concilii under conditions of the previously determined ideal shear stress and pH and at a temperature of 35°C. PMID:17220251
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.
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...
Detecting and escaping infinite loops using Bolt
Kling, Michael (Michael W.)
2012-01-01
In this thesis we present Bolt, a novel system for escaping infinite loops. If a user suspects that an executing program is stuck in an infinite loop, the user can use the Bolt user interface, which attaches to the running ...
Speculative parallelization of partially parallel loops
Dang, Francis Hoai Dinh
2009-05-15
Current parallelizing compilers cannot identify a significant fraction of parallelizable loops because they have complex or statically insufficiently defined access patterns. In our previous work, we have speculatively executed a loop as a doall...
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.
Single anterior tooth replacement by a cast lingual loop connector - a conservative approach.
Dandekeri, Shilpa Sudesh; Dandekeri, Savita
2014-09-01
One of the most challenging and complex treatment modality is replacement of single anterior tooth. This can be overcome by different treatment options such as implant-supported restorations as well as conventional porcelain-fused-to-metal and resin-bonded fixed partial dentures. Drifting of teeth into the edentulous area may reduce the available pontic space; whereas a diastema existing before an extraction may result in excessive mesiodistal dimension to the pontic space. Loop connector fixed partial denture (FPD) may be the simplest and best solution to maintain the diastema and provide optimum restoration of aesthetics. This article describes the procedure for the fabrication of a loop connector FPD to restore an excessively wide anterior edentulous space in a patient with existing spacing between the maxillary anterior teeth. PMID:25386535
Cox, Zachary L; Lenihan, Daniel J
2014-08-01
Loop diuretics are a cornerstone of symptom management for nearly all patients with heart failure. Diuretic resistance is a clinical problem with similar presentation despite diverse and multiple etiologies. Although the exact incidence is not known, diuretic resistance occurs frequently and can increase the length of hospitalization. Despite the prevalence of loop diuretic prescription in heart failure and frequency of diuretic resistance, current heart failure guidelines provide nonspecific guidance on strategies to restore diuretic efficacy. Providers are left with many questions regarding the optimum diuretic titration strategy in the setting of diuretic resistance. In light of these highly prevalent uncertainties, we present a case vignette-structured literature review of the mechanisms of diuretic resistance and recommend therapeutic strategies based on the resistance etiology to improve diuretic response in acute decompensated heart failure. PMID:24879974
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.
Xu, Junyi; Zheng, Qiuyue; Yu, Ling; Liu, Ran; Zhao, Xin; Wang, Gang; Wang, Qinghua; Cao, Jijuan
2013-11-01
The loop-mediated isothermal amplification (LAMP) assay indicates a potential and valuable means for genetically modified organism (GMO) detection especially for its rapidity, simplicity, and low cost. We developed and evaluated the specificity and sensitivity of the LAMP method for rapid detection of the genetically modified (GM) maize T25. A set of six specific primers was successfully designed to recognize six distinct sequences on the target gene, including a pair of inner primers, a pair of outer primers, and a pair of loop primers. The optimum reaction temperature and time were verified to be 65°C and 45 min, respectively. The detection limit of this LAMP assay was 5 g kg(-1) GMO component. Comparative experiments showed that the LAMP assay was a simple, rapid, accurate, and specific method for detecting the GM maize T25. PMID:24804053
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.
LOOP APPROACHES TO GAUGE FIELD THEORIES
R. Loll
1993-01-01
Basic mathematical and physical concepts in loop- and path-dependent formulations of Yang-MiIls theory are reviewed and set into correspondence. We point out some prob- lems peculiar to these non-local approaches, in particular those associated with defining structure on various kinds of loop spaces. The issues of classical loop equations, differen- tial operators, lattice gauge theory, loop algebras, and canonical quantization
Loop approaches to gauge field theories
R. Loll
1992-01-01
Basic mathematical and physical concepts in loop- and path-dependent formulations of Yang-Mills theory are reviewed and set into correspondence. We point out some problems peculiar to these non-local approaches, in particular those associated with defining structure on various kinds of loop spaces. The issues of classical loop equations, differential operators, lattice gauge theory, loop algebras, and canonical quantization are discussed
NASA Astrophysics Data System (ADS)
Zhou, Jing; Li, Qiaoxi; Turner, Sara; Brosnan, Sarah; Tippets, Cary; Carrillo, Jan-Michael; Nykypnachuk, Dmytro; Gang, Oleg; Dobrynin, Andrey; Lopez, Rene; Ashby, Valerie; Sheiko, Sergei
2014-03-01
Reversible shape memory has been achieved on various shapes, e.g. hairpin, origami, coil, robotic gripper and flow rate control device, allowing for multiple switching between encoded shapes without applying any external force. Also, the reversible photonic structure molded in dielectric elastomers has been designed. Maximum reversibility can be achieved by tuning the crosslinking density and the degree of crystallinity of semi-crystalline elastomers. Different crystallization protocols including isothermal and cooling crystallization have been applied to develop a universal picture integrating different shape memory (SM) behaviors: conventional one-way SM, two-way reversible SM, and one-way reversible SM. Acknowledge financial support from the NSF DMR-1122483, DMR- 1004576, and DMR-1206957.
Shaping environmental “justices”
Huang, Chih-Tung
2010-01-01
This thesis investigates the concept of environmental justice (EJ) by tracing its origins, the process of its shaping and reshaping, and its adoption in Taiwan. EJ addresses the phenomenon of disproportionate distribution ...
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.
Connectivity Shapes Martin Isenburg
Lehmann, Daniel
) has the body of a sphere, but the soul of an animal. The embedding in (c) reveals the geometric soul of the cow's connectivity. Connectivity shapes are closest in spirit to the embedding tech- niques used
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.
NASA Astrophysics Data System (ADS)
Li, Xin; Ma, Jing; Yu, Siyuan; Tan, Liying; Shen, Tao
2013-02-01
Channel capacity is widely investigated for free space optical links to approach high-speed data-rate communication. Instead of traditional equiprobable binary symbol input distribution, an optimum input distribution is proposed with respect to channel capacity by maximizing mutual information for intersatellite optical communications in the presence of random pointing jitter. It is shown that the optimum input distribution varies with the variance of pointing jitter ? and laser beam divergence angle w0 and the normalized intensity threshold IT. For traditional normalized intensity threshold IT=0.5, the optimum input distribution ranges from about p(x=0)=0.52 for weak pointing jitter to about p(x=0)=0.24 for strong pointing jitter given the same laser beam divergence angle. The results obtained in this paper will be useful for intersatellite optical communication system design.
Minimum-Weight Sandwich Structure Optimum Design Subjected to Torsional Loading
NASA Astrophysics Data System (ADS)
Li, Xiang; Li, Gangyan; Wang, Chun H.; You, Min
2012-04-01
As one of the most valued structural engineering innovations developed by the composites industry, sandwich structures are now used extensively in automotive, aerospace and civil infrastructure due to the main advantage of lightweight. This paper develops a minimum weight optimization method for sandwich structure subjected to torsion load. The design process are identified for a sandwich structure required to meet the design constraint of torsion stiffness. The optimum solutions show that at optimum design the core weight accounts for 66.7% of the whole sandwich structure. To illustrate the newly developed optimum design solutions, numerical examples are presented for sandwich structures made of either isotropic face skins or orthotropic composite face skins. Agreement between the theoretical analysis and the examples results is good.
Optimum Design of Composite Sandwich Structures Subjected to Combined Torsion and Bending Loads
NASA Astrophysics Data System (ADS)
Li, Xiang; Li, Gangyan; Wang, Chun H.; You, Min
2012-06-01
This research is motivated by the increase use of composite sandwich structures in a wide range of industries such as automotive, aerospace and civil infrastructure. To maximise stiffness at minimum weight, the paper develops a minimum weight optimization method for sandwich structure under combined torsion and bending loads. We first extend the minimum-weight design of sandwich structures under bending load to the case of torsional deformation and then present optimum solutions for the combined requirements of both bending and torsional stiffness. Three design cases are identified for a sandwich structure required to meet multiple design constraints of torsion and bending stiffness. The optimum solutions for all three cases are derived. To illustrate the newly developed optimum design solutions, numerical examples are presented for sandwich structures made of either isotropic face skins or orthotropic composite face skins.
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.
NASA Technical Reports Server (NTRS)
Butler, R.; Williams, F. W.
1992-01-01
A computer program for obtaining the optimum (least mass) dimensions of the kind of prismatic assemblies of laminated, composite plates which occur in advanced aerospace construction is described. Rigorous buckling analysis (derived from exact member theory) and a tailored design procedure are used to produce designs which satisfy buckling and material strength constraints and configurational requirements. Analysis is two to three orders of magnitude quicker than FEM, keeps track of all the governing modes of failure and is efficiently adapted to give sensitivities and to maintain feasibility. Tailoring encourages convergence in fewer sizing cycles than competing programs and permits start designs which are a long way from feasible and/or optimum. Comparisons with its predecessor, PASCO, show that the program is more likely to produce an optimum, will do so more quickly in some cases, and remains accurate for a wider range of problems.
NASA Astrophysics Data System (ADS)
van der Tol, C.; Meesters, A. G. C. A.; Dolman, A. J.; Waterloo, M. J.
2008-03-01
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 calculated using the assumption that growth is maximized. This optimality hypothesis is applied for three scenarios which are increasingly realistic. Optimum parameters reflect a strategy to deal with two tradeoffs: the trade-off between fast growth and avoidance of drought and between a high photosynthetic capacity and avoidance of high respiration losses. The theory predicts general boundary conditions for growth but does not consider effects of competition between species, fires, pest, and diseases or other limitations that occur locally. In a companion paper the theory is evaluated using a data set collected in sub-Mediterranean vegetation.
Design and construct optimum dosimeter to detect airborne radon and thoron gas: Experimental study
NASA Astrophysics Data System (ADS)
Ismail, Asaad H.; Jaafar, Mohamad S.
2011-02-01
Aim of this work is to design and select optimum dimension of a radon and thoron dosimeter within the measure optimum value of the calibration factor, using CR-39 Nuclear Track Detectors (NTDs). The results show that the best dimension to detect and measure real values of airborne radon and thoron concentrations is 6 cm and 7 cm for diameter and height, respectively. Calibration factors (K) for radon and thoron at this dimension were 2.68 ± 0.03 cm and 0.83 ± 0.01 cm, respectively, and these factors relatively depend on the detector efficiency. Therefore, the efficiency of CR-39NTDs to register alpha particles and their effects on the calibration factor estimated. It is found that the calibration factor increased exponentially with detector efficiency. Moreover, detector efficiency was equal to 80.3 ± 1.23% at the optimum dosimeter.
[Optimal permeability of aquaporins: a question of shape?].
Gravelle, Simon; Joly, Laurent; Detcheverry, François; Ybert, Christophe; Cottin-Bizonne, Cécile; Bocquet, Lydéric
2015-02-01
Aquaporins are transmembrane proteins, ubiquitous in the human body. Inserted into the cell membranes, they play an important role in filtration, absorption and secretion of fluids. However, the excellent compromise between selectivity and permeability of aquaporins remains elusive. In this review, we focus on the hourglass shape of aquaporins, and we investigate its influence on water permeability, using numerical calculations and a simple theoretical model. We show that there is an optimum opening angle that maximizes the hydrodynamic permeability, and whose value is close to the angles observed in aquaporins. PMID:25744264
Torque-Matched Aerodynamic Shape Optimization of HAWT Rotor
NASA Astrophysics Data System (ADS)
Al-Abadi, Ali; Ertunç, Özgür; Beyer, Florian; Delgado, Antonio
2014-12-01
Schmitz and Blade Element Momentum (BEM) theories are integrated to a gradient based optimization algorithm to optimize the blade shape of a horizontal axis wind turbine (HAWT). The Schmitz theory is used to generate an initial blade design. BEM theory is used to calculate the forces, torque and power extracted by the turbine. The airfoil shape (NREL S809) is kept the same, so that the shape optimization comprises only the chord and the pitch angle distribution. The gradient based optimization of the blade shape is constrained to the torque-rotational speed characteristic of the generator, which is going to be a part of the experimental set-up used to validate the results of the optimization study. Hence, the objective of the optimization is the maximization of the turbines power coefficient Cp while keeping the torque matched to that of the generator. The wind velocities and the rotational speeds are limited to those achievable in the wind tunnel and by the generator, respectively. After finding the optimum blade shape with the maximum Cp within the given range of parameters, the Cp of the turbine is evaluated at wind-speeds deviating from the optimum operating condition. For this purpose, a second optimization algorithm is used to find out the correct rotational speed for a given wind-speed, which is again constrained to the generator's torque rotational speed characteristic. The design and optimization procedures are later validated by high-fidelity numerical simulations. The agreement between the design and the numerical simulations is very satisfactory.
Lists and Loops 1 Help in Python
Verschelde, Jan
Lists and Loops 1 Help in Python browse Python docs and interactive help 2 Lists in Python defining lists lists as queues and stacks inserting and removing membership and ordering lists 3 Loops in Python 2013 1 / 34 #12;Lists and Loops 1 Help in Python browse Python docs and interactive help 2 Lists