83
83
texts
eye 83
favorite 0
comment 0
In this paper we are interested in the problem of convergence of the eigenvalues and eigenfunctions of the Laplacian with Went zell-Robin boundary condition to the eigenvalues and eigenfunctions of the Laplacien with Dirichlet boundary condition when the Robin parameter tends to infinity. We show in particular that the convergence of eigenfunctions is better than the usual internal convergence in and boundary convergence in
Topics: Laplacien, Went Zell-Robin Boundary Conditions
41
41
texts
eye 41
favorite 0
comment 0
In this paper we are interested in the problem of convergence of the eigenvalues and eigenfunctions of the Laplacian with Went zell-Robin boundary condition to the eigenvalues and eigenfunctions of the Laplacien with Dirichlet boundary condition when the Robin parameter tends to infinity. We show in particular that the convergence of eigenfunctions is better than the usual internal convergence in
Topics: Laplacien, Went Zell-Robin Boundary Conditions
It is known that the Green function of a boundary value problem is a meromorphic function of a spectral parameter. When the boundary conditions contain integro differential terms, then the meromorphism of the Greens function of such a problem can also be proved. In this case, it is possible to write out the structure of the residue at the singular points of the Greens function of the boundary value problem with integro differential perturbations. An analysis of the structure of the residue...
Topics: boundary conditions, Green's function Operator, strongly regular boundary conditions, Riesz basis,...
The stability problem is a fundamental issue in the design of any distributed systems like local area networks, multiprocessor systems, distribution computation and multidimensional queuing systems. In Mathematics stability theory addresses the stability solutions of differential, integral and other equations, and trajectories of dynamical systems under small perturbations of initial conditions. Differential equations describe many mathematical models of a great interest in Economics, Control...
Topics: Applied Mathematics, supper stability, boundary conditions, Intial conditions
150
150
May 6, 2010
05/10
by
Huang, S.-S.; Milligan, J. E.; Stecher, T. P
texts
eye 150
favorite 0
comment 0
Expected boundary conditions of b-stars
Topics: B STARS, BOUNDARY CONDITIONS, MAGNETIC PROPERTIES, B STAR, BOUNDARY
"Upright is modified version of knuckle. It is one of the most critical components in an automotive. Upright is the part that is connected with suspension arms, the hub brake caliper mounting and also the steering tie rod in formula vehicle. For Formula vehicle the goal is to design a light weight, yet sufficiently strong upright. All the loads reacted by the wheels are transmitted to the chassis through the ‘A' arms indirectly from the upright. Generally the nature of the loads is...
Topics: Mechanical Engineering, Upright, Solid Work, ANSYS, Meshing, Boundary conditions
5
5.0
Sep 2, 2020
09/20
by
A.M. Akhtyamov, I.Yu. Trooshin
texts
eye 5
favorite 0
comment 0
This work is dedicated to the solution of direct and inverse spectral problems for Sturm-Liouville differential operators on star-shaped graphs with n+ 1 edges; n edges are finite, and one edge is infinite. Eigenvalues visible at infinity, eigenvalues invisible at infinity and resonances of this spectral problem are found. It is shown that the problem of determining n unknown coefficients of boundary conditions by n eigenvalues visible at infinity and (or) resonances has n! solutions. If the...
Topics: eigenvalues, graph, inverse problems, Kirchhoff boundary conditions, Jost solution
362
362
Jun 12, 2011
06/11
by
NON
texts
eye 362
favorite 0
comment 0
This report lists NASA patent abstracts recently announced in the NASA STI Database.
Topics: CLOCKS, BOUNDARY CONDITIONS, ACCURACY, FINITE ELEMENT METHOD, SYSTEMATIC ERRORS
110
110
Mar 4, 2015
03/15
by
Innovative Research Publications
texts
eye 110
favorite 0
comment 0
Air circulation study is most important part for any building; so that engineers can optimize thermal comfort for buildings. A computer lab located in university building of Jaipur city is used in this study. Main aim of this study is to optimize computer lab for two types of conditions, first is only internal fans are in operational condition and second condition is effect of room window opening and closing. Thermal comfort parameters are used for analysis. Model equations are also generated...
Topics: CFD, Dimensionless numbers, Turbulence models, fan boundary conditions, radiation modeling
In this research article, a model for the transmission dynamics of haemorghagic conjunctivitis disease is presented. The tool of dynamical system is employed in investigating the potency of the spreading of the epidemic. The analysis revealed the likelihood of the epidemic to spread when the the basic reproduction number exceeds one. The model is reformulated as optimal control problem to assess the effectiveness of the proposed control strategy. Maximum Principle was employed to derive the...
Topics: Basic reproduction ratio, Pontryagin’s maximum principle, Lagrangian, Hamiltonain, Boundary...
7
7.0
Jan 29, 2020
01/20
by
@iaset
texts
eye 7
favorite 0
comment 0
In the paper, it is constructed with difference schemes which approximately mixed problem for heat equation and shown their stability. There exist various methods to develop difference schemes which are mainly based on exchanging derivatives with difference schemes
Topics: Difference Schemes, Wave Equation, Approximation, Finite Difference, Stability, Boundary Conditions
746
746
May 31, 2011
05/11
by
Greene, William D.; Boxx, Dayna L
texts
eye 746
favorite 0
comment 0
The subject of cryogenic propellant densification as a potential upgrade to the Space Shuttle is a subject that has been raised on several occasions over the last decade. Due to advancements in densification technology made as a part of and in parallel to the X-33 project, the subject was raised and studied once again in May 2001. Across the Space Shuttle program people from many disciplines converged to discuss issues and perform trade studies to determine whether densified propellants was...
Topics: AIRFOILS, GUSTS, AEROACOUSTICS, BOUNDARY CONDITIONS, DYNAMIC RESPONSE, COMPUTATIONAL GRIDS,...
8
8.0
Feb 12, 2020
02/20
by
@IASET
texts
eye 8
favorite 0
comment 0
In the paper, it is constructed with difference schemes which approximately mixed problem for heat equation and shown their stability. There exist various methods to develop difference schemes which are mainly based on exchanging derivatives with difference schemes
Topics: Difference Schemes, Wave Equation, Approximation, Finite Difference, Stability, Boundary Conditions
190
190
May 23, 2011
05/11
by
Glazman, Roman E
texts
eye 190
favorite 0
comment 0
Employing a recently proposed 'multi-wave interaction' theory, inertial spectra of capillary gravity waves are derived. This case is characterized by a rather high degree of nonlinearity and a complicated dispersion law. The absence of scale invariance makes this and some other problems of wave turbulence (e.g., nonlinear inertia gravity waves) intractable by small-perturbation techniques, even in the weak-turbulence limit. The analytical solution obtained in the present work for an arbitrary...
Topics: CORONAL HOLES, MAGNETOHYDRODYNAMIC FLOW, SOLAR CORONA, BOUNDARY CONDITIONS, MATHEMATICAL MODELS,...
4
4.0
Sep 7, 2020
09/20
by
differential-operator equation, spectral parameter in boundary conditions, eigenvalue, asymptotic formula.
texts
eye 4
favorite 0
comment 0
On eigenvalues of a boundary value problem for a second order elliptic differential-operator equation
Topics: differential-operator equation, spectral parameter in boundary conditions, eigenvalue, asymptotic...
Recent research has revealed a surge in the application of Stochastic Differential Equations (SDEs) in the modeling of infectious diseases. Factors emanating from this surge has been the ability of stochastic differential equations to lay one of the most imperative fundamental differences in the asymptotic dynamics of the deterministic and stochastic epidemic models [1]. These fundamental differences include the convergence of the sample path of stochastic models to the disease-free state and...
Topics: Pontryagin’s Maximum Principle, Lagrangian, Hamiltonain, Boundary conditions, Stochastic...
In this research article, an optimal control model of malaria disease with standard incidence rate is proposed. Maximum Principle was employed to derive the necessary conditions for the existence of optimal control. Stochastic version of the model is derived by introducing a random perturbation in the main parameters of the model equations. Numerical solution of the optimality was derived and computed to investigate the optimum control strategy that would be efficacious to be implemented in...
Topics: Pontryagin’s Maximum Principle, Lagrangian, Hamiltonain, Boundary conditions, Stochastic...
916
916
May 29, 2011
05/11
by
Wagner, Herber
texts
eye 916
favorite 0
comment 0
The matter dealt with in the present paper has a direct bearing on the taking-off and alighting of seaplanes. The liquid is assumed as being non-viscous and incompressible, and the acceleration due to gravity is neglected. The following considerations therefore apply the more exactly the smaller the body and the more quickly it moves. In the case of prolonged. and primarily of uniform processors, the arguments hold only in the close neighborhood of the body. The investigations deal first with...
Topics: AEROACOUSTICS, SOUND WAVES, VORTEX SHEDDING, NUMERICAL ANALYSIS, SIMULATION, BOUNDARY CONDITIONS,...
272
272
Jun 1, 2011
06/11
by
Martin, P. B.; McAlister, K. W.; Chandrasekhara, M. S.; Geissler, W
texts
eye 272
favorite 0
comment 0
High density-altitude operations of helicopters with advanced performance and maneuver capabilities have lead to fundamental research on active high-lift system concepts for rotor blades. The requirement for this type of system was to improve the sectional lift-to-drag ratio by alleviating dynamic stall on the retreating blade while simultaneously reducing the transonic drag rise of the advancing blade. Both measured and computational results showed that a Variable Droop Leading Edge (VDLE)...
Topics: REUSABLE LAUNCH VEHICLES, TRAJECTORY PLANNING, BOUNDARY CONDITIONS, ALGORITHMS, FLIGHT PLANS,...
242
242
May 24, 2011
05/11
by
Wong, George S.; Waldrop, Glen S
texts
eye 242
favorite 0
comment 0
The OEPSS video film, along with the OEPSS Databooks, provides a data base of current launch experience that will be useful for design of future expendable and reusable launch systems. The focus is on the launch processing of propulsion systems. A brief 15-minute overview of the OEPSS study results is found at the beginning of the film. The remainder of the film discusses in more detail: current ground operations at the Kennedy Space Center; typical operations issues and problems; critical...
Topics: BOUNDARY CONDITIONS, AEROACOUSTICS, COMPUTATION, SIMULATION, ENCOUNTERS, DISSIPATION, ALGORITHMS,...
For an axially compressed cylinder, early experiments revealed that the experimental load is about 30% below the theoretical load. This paper aims to provide better comparison between experimental and theoretical data for cylinders subjected to axial compression through the appropriate experimental procedure. Ten cylinders (five steel and five aluminum) were made using different joining techniques. Two cylindrical geometric parameters were considered, they are : (i) thinness ratio (i. e.,...
Topics: Buckling, Cylindrical Shell, ABAQUS, Axial Compression, Numerical/Theoretical Prediction &...
686
686
Jun 1, 2011
06/11
by
Sellers, William L., III; Singer, Bart A.; Leavitt, Laurence D
texts
eye 686
favorite 1
comment 0
Aeronautics research has seriously declined partly because of the perception that it is a mature science and only incremental improvements are possible. Recent aeronautics roadmapping activities at NASA Langley paint a different picture of the future. Breakthroughs are still felt to be possible if we expand the current design space of today's vehicles and optimize the airspace and vehicles as a system. The paper describes some of the challenges that the aircraft and airline industry face. These...
Topics: PRESSURE MEASUREMENT, SUBSONIC WIND TUNNELS, BOUNDARY CONDITIONS, COMPUTATIONAL FLUID DYNAMICS,...
In the present study, an unmanned aerial vehicle is designed and analyzed. As per the requirement of lifting a payload of 1.5kg, hexacopter suits the mission profile. Rational design plays an important role in the design process which starts with the weight estimation and the chosen mission profile. A refined method is adopted based on the calculated parameters to achieve the geometry of the hexacopter. Hexacopter is designed using the design software CATIA V5. In addition to that, static...
Topics: Hexacopter, Thrust, Lift, Propeller, Clamp, FEM Analysis, Loads and Boundary Conditions &...
186
186
May 6, 2010
05/10
by
Reinhardt, W. A
texts
eye 186
favorite 0
comment 0
Numerical predictions of nonlinear diffusion with homogeneous recombination and time-varying boundary conditions
Topics: BOUNDARY CONDITIONS, RECOMBINATION, DIFFUSION, HOMOGENEITY, NONLINEARITY, NUMERICAL ANALYSIS,...
This paper presents the evaluation of several solid wall boundary conditions when used in the numerical solution of the Boltzmann equation using the finite-difference/finitevolume methods. Five solid wall boundary conditions are considered: (a) adsorption, (b) specular reflection, (c) diffuse reflection, (d) Maxwellian reflection, and (e) adsorptive Maxwellian reflection. The boundary conditions are applied on a two-dimensional discretized velocity space mesh. Methods for applying the same...
Topics: Boltzmann Equation, Non-equilibrium Hypersonic Flows, Wall Boundary Conditions for Boltzmann...
364
364
Jun 1, 2011
06/11
by
Stieglitz, Alber
texts
eye 364
favorite 0
comment 0
Various versions of pendulum masses have been developed abroad within the past few years by means of which resonant vibrations of rotating shafts can be eliminated at a given tuning. They are already successfully employed on radial engines in the form of pendulous counterweights. Compared with the commonly known torsional vibration dampers, the pendulum masses have the advantage of being structurally very simple, requiring no internal damping and being capable of completely eliminating certain...
Topics: THIN WALLED SHELLS, STRESS FUNCTIONS, DIFFERENTIAL EQUATIONS, MODULUS OF ELASTICITY, BOUNDARY...
133
133
Jun 1, 2011
06/11
by
Fucha, D
texts
eye 133
favorite 0
comment 0
Unduly high diving speeds can be effectively controlled by diving brakes but their employment involves at the same time a number of disagreeable features: namely, rotation of zero lift direction, variation of diviving moment, and, the creation of a potent dead air region.
Topics: SPACE-TIME CE/SE METHOD, BOUNDARY CONDITIONS, FLOW EQUATIONS, ADVECTION, SHOCK TUBES
191
191
Jun 3, 2011
06/11
by
Wilson, William C.; Atkinson, Gary M
texts
eye 191
favorite 0
comment 0
We investigate a concept for the construction a mobile Micro Optical ElectroMechanical Systems (MOEMS) based laser ultrasonic instrument to serve as a Micro Autonomous Ultrasonic Instrument (MAUI). The system will consist of a laser ultrasonic instrument fabricated using Micro Electro-Mechanical Systems (MEMS) technology, and a MEMS based walking platform like those developed by Pister et al. at Berkeley. This small system will allow for automated remote Non-Destructive Evaluation (NDE) of...
Topics: BOUNDARY CONDITIONS, BUCKLING, DEFORMATION, LAMINATES, PLATES (STRUCTURAL MEMBERS), NONLINEAR...
The objective of this thesis is to develop a prognostic model of the Northern Canary Current System (NCCS) based on the Princeton Ocean Model with parallel processing capabilities on a cluster of workstations and improved boundary conditions. A one-way coupling with a z-level basin scale model, a North Atlantic version of the Parallel Ocean Program, will also be executed. The development of this model will allow the investigation of coastal processes and the development of numerical models in...
Topics: Submarine topography|zAtlantic Ocean., Sigma Coordinate Model, Parallelization, MPI, Boundary...
In this paper, two-dimensional equation, subject to Dirichlet initial boundary conditions is presented, and a Spline Collocation Method is utilized for solving the problem. Also, Spline provides continuous solution, in contrast to another method, which only provides discrete approximations. It is found that this method is a powerful mathematical tool and can be applied to a large class of linear and nonlinear problems in different fields of science and technology. Numerical results obtained by...
Topics: Spline Collocation Method, Partial Differential Equations, Two Dimensional Hyperbolic Equation...
5
5.0
Sep 2, 2020
09/20
by
M.J. Mardanov, Y.A. Sharifov∗ , R.A. Sardarova, H.N. Aliyev
texts
eye 5
favorite 0
comment 0
The aim of this paper is to investigate the solution of the system of nonlinear impulsive differential equations with three-point and integral boundary conditions. The Green function is constructed and the original problem is reduced to the equivalent integral equations. Sufficient conditions are found for the existence and uniqueness of solutions to the boundary value problems for the system of first order nonlinear impulsive ordinary differential equations with three-point and integral...
Topics: : three-point and integral boundary conditions, existence, uniqueness, fixed point, impulsive...
245
245
Jun 3, 2011
06/11
by
Harman, R.; Thienel, J.; Oshman, Yaako
texts
eye 245
favorite 0
comment 0
This paper documents the testing and development of magnetometer-based gyroless attitude and rate estimation algorithms for the Far Ultraviolet Spectroscopic Explorer (FUSE). The results of two approaches are presented, one relies on a kinematic model for propagation, a method used in aircraft tracking, and the other is a pseudolinear Kalman filter that utilizes Euler's equations in the propagation of the estimated rate. Both algorithms are tested using flight data collected over a few months...
Topics: LEADING EDGES, STAGNATION FLOW, MULTIGRID METHODS, INVISCID FLOW, FLOW EQUATIONS, BOUNDARY...
543
543
Jul 23, 2010
07/10
by
Kovach, L. S.; Zdankiewicz, E. M
texts
eye 543
favorite 0
comment 0
Vapor compression distillation technology for phase change recovery of potable water from wastewater has evolved as a technically mature approach for use aboard the Space Station. A program to parametrically test an advanced preprototype Vapor Compression Distillation Subsystem (VCDS) was completed during 1985 and 1986. In parallel with parametric testing, a hardware improvement program was initiated to test the feasibility of incorporating several key improvements into the advanced...
Topics: BARS, BOUNDARY CONDITIONS, BOUNDARY VALUE PROBLEMS, MATHEMATICAL MODELS, PROBLEM SOLVING,...
272
272
Jun 13, 2011
06/11
by
Lindstrom, Gary; Mehlitz, Peter C.; Visser, Wille
texts
eye 272
favorite 0
comment 0
The Real Time Specification for Java (RTSJ) is an augmentation of Java for real time applications of various degrees of hardness. The central features of RTSJ are real time threads; user defined schedulers; asynchronous events, handlers, and control transfers; a priority inheritance based default scheduler; non-heap memory areas such as immortal and scoped, and non-heap real time threads whose execution is not impeded by garbage collection. The Robust Software Systems group at NASA Ames...
Topics: SPACE-TIME FUNCTIONS, FINITE DIFFERENCE THEORY, ELECTROMAGNETIC RADIATION, COSMOLOGY, BOUNDARY...
2,762
2.8K
May 29, 2011
05/11
by
Orloff, Richar
texts
eye 2,762
favorite 3
comment 0
The purpose of this work is to provide researchers, students, and space enthusiasts with a comprehensive reference for facts about Project Apollo, America's effort to put humans in the Moon. Research for this work started in 1988, when the author discovered that, despite the number of excellent books that focused on the drama of events that highlighted Apollo, there were none that focused on the drama of the numbers. This book is separated into two parts. The first part contains narratives for...
Topics: LIQUID SURFACES, SEAPLANES, AMPHIBIOUS AIRCRAFT, WATER LANDING, AIRCRAFT LANDING, SLIDING, BOUNDARY...
In structural engineering, a finite element model is often used to estimate its dynamic or static behavior, and in conjunction with measured data, to monitor the health of a structure. This research is focusing on the use of experimental data for the improvement of a finite element model such that it accurately represents the structure, and in the localization of artificial damage in the model. The method of Artificial Boundary Conditions in model update and damage identification is used. To...
Topics: artificial boundary conditions, finite element model, model update, damage identification, natural...
236
236
Jun 2, 2011
06/11
by
Choi, Sung R.; Gyekenyesi, John P
texts
eye 236
favorite 0
comment 0
Mechanical testing for Pyroceram (trademark) 9606 glass-ceramic fabricated by Corning was conducted to determine mechanical properties of the material including slow crack growth.Valid testing was not achieved in tension, compression, and shear testing due to inappropriate test specimen configurations provided and primarily due to the existence of fortified layer( in tension).
Topics: BOUNDARY CONDITIONS, DIRECT NUMERICAL SIMULATION, GALERKIN METHOD, DECOMPOSITION, PERFECTLY MATCHED...
297
297
Jun 2, 2011
06/11
by
McClure, Megan S.; Johnson, Jeffrey L
texts
eye 297
favorite 0
comment 0
Tilt rotors are a new breed of subsonic aircraft developed for both military and civil aviation. The current production of the military V-22 Osprey and the launch decision of the BA-609 civil tilt rotor will certainly enhance the U.S. military and economic competitive status in the international aviation arena. In addition, civil tilt rotors have the potential to increase air transportation throughput in congested airports by off-loading busy runways. To support the U.S. civil tilt-rotor...
Topics: BOUNDARY CONDITIONS, CRYOGENIC COOLING, HEAT TRANSFER, STROUHAL NUMBER, STEADY FLOW, ENTHALPY,...
245
245
Jun 1, 2011
06/11
by
Encke, W
texts
eye 245
favorite 0
comment 0
A selection of measurements obtained on experimental impellers for axial blowers will be reported. In addition to characteristic curves plotted for low and for high peripheral velocities, proportions and blade sections for six different blower models and remarks on the design of blowers will be presented.
Topics: CONICAL FLOW, SUPERSONIC FLOW, AIRCRAFT DESIGN, DIFFERENTIAL EQUATIONS, MACH CONES, GAS FLOW,...
500
500
May 30, 2011
05/11
by
Sullins, Alan D.; Daryabeigi, Kamra
texts
eye 500
favorite 0
comment 0
The effective thermal conductivity of high-porosity open cell nickel foam samples was measured over a wide range of temperatures and pressures using a standard steady-state technique. The samples, measuring 23.8 mm, 18.7 mm, and 13.6 mm in thickness, were constructed with layers of 1.7 mm thick foam with a porosity of 0.968. Tests were conducted with the specimens subjected to temperature differences of 100 to 1000 K across the thickness and at environmental pressures of 10(exp -4) to 750 mm...
Topics: BOUNDARY CONDITIONS, COMPUTATION, POROSITY, SIMULATION, MATHEMATICAL MODELS, AERODYNAMICS,...
396
396
Jun 13, 2011
06/11
by
Davis, Brian A
texts
eye 396
favorite 0
comment 0
Previous work at NASA Langley Research Center (LaRC) involved fabrication and testing of composite beams with embedded, pre-strained shape memory alloy (SMA) ribbons. That study also provided comparison of experimental results with numerical predictions from a research code making use of a new thermoelastic model for shape memory alloy hybrid composite (SMAHC) structures. The previous work showed qualitative validation of the numerical model. However, deficiencies in the experimental-numerical...
Topics: COMPUTATIONAL FLUID DYNAMICS, CONVERGENCE, BOUNDARY CONDITIONS, LAPLACE EQUATION, ALGORITHMS,...
1,283
1.3K
Aug 1, 2010
08/10
by
Taranik, James V.; Hsu, Liang C.; Spatz, David M.; Chenevey, Michael J
texts
eye 1,283
favorite 0
comment 0
The following subject areas are covered: (1) genetic, spectral, and LANDSAT Thematic Mapper imagery relationship between desert varnish and tertiary volcanic host rocks, southern Nevada; (2) reconnaissance geologic mapping of the Kane Springs Wash Volcanic Center, Lincoln County, Nevada, using multispectral thermal infrared imagery; (3) interregional comparisons of desert varnish; and (4) airborne scanner (GERIS) imagery of the Kane Springs Wash Volcanic Center, Lincoln County, Nevada.
Topics: ACOUSTICS, FREQUENCY RANGES, TIME, BOUNDARY CONDITIONS, DUCTS, REFLECTANCE, SOUND WAVES, WALLS,...
Proceedings of a Second Symposium on Large Scale Digital Calculating Machinery, Jointly Sponsored by the Navy Department Bureaur of Ordnance and Harvard University at the Computation Laboratory, September 13-16, 1949. Includes: Program of the Symposium, Members of the Symposium, Opening Addresses, Recent Developments in Computing Machinery, Banquet, Numerical Methods, computational Problems in Physics, Aeronautics and Applied Mechanics, The Economic and Social Sciences, Discussion and...
Topics: computing, computation, harvard, matrix, cambridge, machine, equations, method, values,...
227
227
May 30, 2011
05/11
by
Ku, Jentung; Ottenstein, Laura; Rogers, Paul; Cheung, Kwo
texts
eye 227
favorite 0
comment 0
This paper presents test results of an experimental study of low power operation in a loop heat pipe. The main objective was to demonstrate how changes in the vapor void fraction inside the evaporator core would affect the loop behavior, The fluid inventory and the relative tilt between the evaporator and the compensation chamber were varied so as to create different vapor void fractions in the evaporator core. The effect on the loop start-up, operating temperature, and capillary limit was...
Topics: ALGORITHMS, NAVIER-STOKES EQUATION, UNSTRUCTURED GRIDS (MATHEMATICS), UPWIND SCHEMES (MATHEMATICS),...
299
299
May 22, 2011
05/11
by
NON
texts
eye 299
favorite 0
comment 0
Gimballed scanning devices or instruments are the subject of this invention. Scanning is an important aspect of space science. To achieve a scan pattern some means must be provided which impart to the payload an oscillatory motion. Various forms of machines have been employed for controllably conferring on scanning instruments predetermined scan patterns. They include control moment gyroscopes, reaction wheels, torque motors, reaction control systems, and the like. But rotating unbalanced mass...
Topics: CAVITATION FLOW, COMPUTATIONAL FLUID DYNAMICS, IMPELLERS, TURBINE PUMPS, BOUNDARY CONDITIONS,...
Single point incremental forming (SPIF) has a great contribution in industrial practice, because the desired parts such as the small-batch production and prototype products can be manufactured just by changing the punch tools and supports. The sheet is formed into desired part using punch tools by producing local plastic deformations at the contact locations based on designed tool paths. This research work is aimed to investigate the formability of SPIF process over the numerical simulations in...
Topics: Single Point Incremental Forming, Finite Element Model, Thinning Location, Base Plate Configuration...
240
240
Jun 2, 2011
06/11
by
Netzer, Hagai; George, Steven B., et al; Kaspi, Shai; Behar, Ehud; Brandt, W. N.; Chelouche, Doron; George, Ian M.; Crenshaw, D. Michael; Gabel, Jack R.; Hamann, Frederick W.
texts
eye 240
favorite 0
comment 0
We present a detailed analysis of the 900 ks spectrum of NGC3783 obtained by Chandra in 2000-2001 (Kaspi et al. 2002). We split the data in various ways to look for time dependent and luminosity dependent spectral variations. This analysis, the measured equivalent widths of a large number of X-ray lines, and our photoionization calculations, lead us to the following conclusions: 1) NGC 3783 fluctuated in luminosity, by a factor N 1.5, during individual 170 ks observations. The fluctuations were...
Topics: BOUNDARY CONDITIONS, PLANE WAVES, CONSERVATION LAWS, WAVE PROPAGATION, REFLECTION, HYPERBOLIC...
328
328
May 31, 2011
05/11
by
NON
texts
eye 328
favorite 0
comment 0
Tensegritoy, inspired by the tensegrity concepts of R. Buckminster Fuller, is an erector set like toy designed to give students an understanding of structural stability. It is used by children, architects, engineers, and teachers. The manufacturer, Tensegrity Systems Corporation, also offers a collapsible point of purchase display which incorporates technology developed for space station trusses described in ''NASA Tech Briefs.'' The tech brief described deployable trusses that can be collapsed...
Topics: COMPUTATIONAL FLUID DYNAMICS, BOUNDARY CONDITIONS, SUPERSONIC INLETS, SUPERSONIC FLOW, UNSTEADY...
21
21
texts
eye 21
favorite 0
comment 0
Abstract — Stochastic advection diffusion equation (SADE) with multiplicative stochastic input is a practical mathematical model for different physical phenomena. In this paper, SADE will be studied using two spectral stochastic techniques. The first is the Wiener chaos expansion (WCE) technique and the second is the Wiener-Hermite expansion with perturbation (WHEP) technique. These techniques convert the SADE into a system of deterministic partial differential equation (DPDE) that can be...
Topics: Advection diffusion equation, Multiplicative random input, Wiener-Hermite expansion, Wiener-Chaos...
131
131
Jul 23, 2010
07/10
by
Kandil, Osama A
texts
eye 131
favorite 0
comment 0
The steady full-potential equation is written in the form of Poisson's equation, and the solution for the velocity field is expressed in terms of an integral equation. The integral solution consists of two surface integrals and one volume integral. The solution is obtained through successive iteration cycles. Each cycle of iteration consists of two sub-cycles, an inner cycle for wake relaxation and an out cycle for the strength of the source distribution integrals representing the flow...
Topics: BOUNDARY VALUE PROBLEMS, DECOMPOSITION, DOMAINS, INTERFACES, BOUNDARY CONDITIONS, NUMERICAL...
