Boeing (United States)

A constrained least mean-squares algorithm has been derived which is capable of adjusting an array of sensors in real time to respond to a signal coming from a desired direction while discriminating against noises coming from other directions. Analysis and computer simulations confirm that the algorithm is able to iteratively adapt variable weights on the taps of the sensor array to minimize noise power in the array output. A set of linear equality constraints on the weights maintains a chosen frequency characteristic for the array in the direction of interest. The array problem would be a classical constrained least-mean-squares problem except that the signal and noise statistics are assumed unknown a priori. A geometrical presentation shows that the algorithm is able to maintain the constraints and prevent the accumulation of quantization errors in a digital implementation.

Past evidence suggests that a large-scale orderly pattern may exist in the noiseproducing region of a jet. Using several methods to visualize the flow of round subsonic jets, we watched the evolution of orderly flow with advancing Reynolds number. As the Reynolds number increases from order 10 2 to 10 3 , the instability of the jet evolves from a sinusoid to a helix, and finally to a train of axisymmetric waves. At a Reynolds number around 10 4 , the boundary layer of the jet is thin, and two kinds of axisymmetric structure can be discerned: surface ripples on the jet column, thoroughly studied by previous workers, and a more tenuous train of large-scale vortex puffs. The surface ripples scale on the boundary-layer thickness and shorten as the Reynolds number increases toward 10 5 . The structure of the puffs, by contrast, remains much the same: they form at an average Strouhal number of about 0·3 based on frequency, exit speed, and diameter. To isolate the large-scale pattern at Reynolds numbers around 10 5 , we destroyed the surface ripples by tripping the boundary layer inside the nozzle. We imposed a periodic surging of controllable frequency and amplitude at the jet exit, and studied the response downstream by hot-wire anemometry and schlieren photography. The forcing generates a fundamental wave, whose phase velocity accords with the linear theory of temporally growing instabilities. The fundamental grows in amplitude downstream until non-linearity generates a harmonic. The harmonic retards the growth of the fundamental, and the two attain saturation intensities roughly independent of forcing amplitude. The saturation amplitude depends on the Strouhal number of the imposed surging and reaches a maximum at a Strouhal number of 0·30. A root-mean-square sinusoidal surging only 2% of the mean exit speed brings the preferred mode to saturation four diameters downstream from the nozzle, at which point the entrained volume flow has increased 32% over the unforced case. When forced at a Strouhal number of 0·60, the jet seems to act as a compound amplifier, forming a violent 0·30 subharmonic and suffering a large increase of spreading angle. We conclude with the conjecture that the preferred mode having a Strouhal number of 0·30 is in some sense the most dispersive wave on a jet column, the wave least capable of generating a harmonic, and therefore the wave most capable of reaching a large amplitude before saturating.

Abstract. The Model for Ozone and Related chemical Tracers, version 4 (MOZART-4) is an offline global chemical transport model particularly suited for studies of the troposphere. The updates of the model from its previous version MOZART-2 are described, including an expansion of the chemical mechanism to include more detailed hydrocarbon chemistry and bulk aerosols. Online calculations of a number of processes, such as dry deposition, emissions of isoprene and monoterpenes and photolysis frequencies, are now included. Results from an eight-year simulation (2000–2007) are presented and evaluated. The MOZART-4 source code and standard input files are available for download from the NCAR Community Data Portal (http://cdp.ucar.edu).

Detached-eddy simulation (DES) was first proposed in 1997 and first used in 1999, so its full history can be surveyed. A DES community has formed, with adepts and critics, as well as new branches. The initial motivation of high–Reynolds number, massively separated flows remains, for which DES is convincingly more capable presently than either unsteady Reynolds-averaged Navier-Stokes (RANS) or large-eddy simulation (LES). This review discusses compelling examples, noting the visual and quantitative success of DES. Its principal weakness is its response to ambiguous grids, in which the wall-parallel grid spacing is of the order of the boundary-layer thickness. In some situations, DES on a given grid is then less accurate than RANS on the same grid or DES on a coarser grid. Partial remedies have been found, yet dealing with thickening boundary layers and shallow separation bubbles is a central challenge. The nonmonotonic response of DES to grid refinement is disturbing to most observers, as is the absence of a theoretical order of accuracy. These issues also affect LES in any nontrivial flow. This review also covers the numerical needs of DES, gridding practices, coupling with different RANS models, derivative uses such as wall modeling in LES, and extensions such as zonal DES and delayed DES.

7R21. Practical Methods for Optimal Control using Nonlinear Programming. - JT Betts (Res and Tech Div, Boeing Co, Seattle WA). SIAM, Philadelphia. 2001. 190 pp. ISBN 0-89871-488-5. $51.00. Reviewed by I Kolmanovsky (Sci Res Lab, MD-2036, Ford Motor Co, 2101 Village Rd, Dearborn MI 48124).System models are routinely developed in engineering and other disciplines for system analysis and simulation. They now find widespread use in industry in all phases of design and development of technological systems. Model-based trajectory optimization and optimal control are among key tools that facilitate finding better ways to operate and control complex engineering systems. They are also becoming essential in the design phase, to determine system parameters which meet stringent performance objectives and constraints. In this regard, this book is quite timely. Its detailed treatment of methods and strategies used to solve such optimal control and trajectory optimization problems (complete with in-depth discussion of implementation, tricks, and “what can go wrong” issues) will be useful to optimization practitioners and insightful to researchers focused on various aspects of optimization. The focus of the book is a family of techniques (often referred to as direct methods) wherein the optimal control problem is converted into a finite-dimensional optimization problem using method of transcription. The finite-dimensional problem can be solved using nonlinear programming techniques. The basic idea of transcription is to treat the values of the state and control variables at discrete-time instants as free variables to which constrained, nonlinear programming optimization can then be applied. The constraints are inherited from the original optimal control problem formulation and are also induced by the discretization/integration of the differential equations governing the system dynamics. Efficient computational strategies can be developed if the nonlinear programming algorithm used in the second stage takes advantage of the structure of the problem (sparsity), which is induced as a result of integrating the dynamics equations in the first phase. The book is very readable. In part, it is due to its theorem-free format while relying instead on a detailed discussion and illustration of how to setup numerical methods and strategies to solve optimal control problems, what can happen, and what can go wrong. Enough detail is given so that the reader also gets a good flavor of the nature of rigorous theoretical results (found in the references provided in the book). The book is organized as follows. The first chapter reviews the main ideas and techniques of nonlinear programming, including unconstrained minimization methods (Newton and quasi-Newton methods) and constrained optimization techniques (such as Sequential Quadratic Programming or SQP). The review is concise and self-contained, providing the reader quick access to the main ideas used in high-performance optimization codes. Practical issues of what can go wrong such as infeasible constraints, discontinuous objective functions, rank-deficient constraints, and constraint redundancy are illustrated with specific examples. Practical remedies to handle these difficulties are discussed. Chapter 2 discusses large scale nonlinear programming problems and, in particular, the case when the Hessian matrix and Jacobian matrix are sparse, that is most of their elements are zero. In this situation, sparse finite differences can be used to approximate first and second derivatives in a computationally efficient fashion. This and the resulting sparse SQP algorithm are described in detail. Chapter 3 reviews several classical numerical methods for solving initial and boundary value problems for ordinary differential equations. It is the central idea of the book that numerical methods for solving (integrating or discretizing) ODEs give rise to nonlinear programming problems which are sparse, and the sparsity properties depend on a particular method used for discretization. Thus after the transcription, it is possible to take advantage of a particular sparse structure (induced by a particular discretization method) in solving the nonlinear programming problem. This is basically the subject of Chapter 4. What can go wrong is discussed including how to recognize the emergence of singular arcs and discontinuous control, as well as consideration of the issues involved in problems with state constraints. Strategies to switch from lower order ODE integration routines (used at the beginning) to higher order routines as well as mesh refinement strategies are detailed. Chapter 5 reports several of the numerical case studies that the author successfully solved in the past using the techniques described in the book. They are examples of realistic trajectory optimization problems, primarily drawn from the aerospace field. They are, respectively: Space shuttle reentry trajectory optimization, minimum time to climb for an aeroplane, low-thrust orbit transfer for a spacecraft, and two burn orbit transfer for a spacecraft, as well as trajectory optimization for an industrial robot and a multibody mechanism. These case studies provide a good illustration of the techniques described in the book and describe additional strategies to deal with particular issues and problem formulations. On a critical side, the book only covers one particular class of techniques for solving optimal control problems. Methods based on dynamic programming (which provide optimal control policy in a feedback form) and methods based on calculated gradients through the solution of adjoint equations are not covered. The latter are discussed, with an argument that the adjoint equation approach may not often be applied to the complex models anyway since they may not admit a readily available symbolic representation adequate for the development of linearized equations. The techniques described in the book are implemented in software called SOCS, commercially available from Boeing. This software is briefly described in the Appendix. A limited version of this software (trial version) or other computational codes for the reader to experiment with would amplify the appeal of this book, but are presently not available. In summary, Practical Methods for Optimal Control using Nonlinear Programming will be useful and is recommended to researchers and engineers in industry and academia whose projects involve solving optimal control/trajectory optimization problems. The book can also be used, as a supplemental text, in graduate-level university courses on optimal control and numerical methods in optimal control. It should also be possible to develop a special topics graduate-level course based on the material in this book, supplemented with theoretical details from the reference literature.

A new correlation-based transition model has been developed, which is built strictly on local variables. As a result, the transition model is compatible with modern computational fluid dynamics techniques such as unstructured grids and massively parallel execution. The model is based on two transport equations, one for intermittency and one for a transition onset criterion in terms of momentum-thickness Reynolds number. A number of validation papers have been published on the basic formulation of the model. However, until now the full model correlations have not been published. The main goal of the present paper is to publish the full model and release it to the research community so that it can continue to be further validated and possibly extended or improved. Included in this paper are a number of test cases that can be used to validate the implementation of the model in a given computational fluid dynamics code. The authors believe that the current formulation is a significant step forward in engineering transition modeling, as it allows the combination of transition correlations with general-purpose computational fluid dynamics codes. There is a strong potential that the model will allow the first-order effects of transition to be included in everyday industrial computational fluid dynamics simulations.

The authors describe the design and prototyping steps they have taken toward the implementation of a heads-up, see-through, head-mounted display (HUDset). Combined with head position sensing and a real world registration system, this technology allows a computer-produced diagram to be superimposed and stabilized on a specific position on a real-world object. Successful development of the HUDset technology will enable cost reductions and efficiency improvements in many of the human-involved operations in aircraft manufacturing, by eliminating templates, formboard diagrams, and other masking devices.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

We have applied Fourier analysis to our point-scattering theory of x-ray absorption fine structure to invert experimental data formally into a radial structure function with determinable structural parameters of distance from the absorbing atom, number of atoms, and widths of coordination shells. The technique is illustrated with a comparison of evaporated and crystalline Ge. We find that the first and second neighbors in amorphous Ge are at the crystalline distance within the accuracy of measurement (1%).

The W3C Semantic Sensor Network Incubator group (the SSN-XG) produced an OWL 2 ontology to describe sensors and observations — the SSN ontology, available at http://purl.oclc.org/NET/ssnx/ssn. The SSN ontology can describe sensors in terms of capabilities, measurement processes, observations and deployments. This article describes the SSN ontology. It further gives an example and describes the use of the ontology in recent research projects.

The axisymmetric turbulent incompressible and isothermal jet was investigated by use of linearized constant-temperature hot-wire anemometers. It was established that the jet was truly self-preserving some 70 diameters downstream of the nozzle and most of the measurements were made in excess of this distance. The quantities measured include mean velocity, turbulence stresses, intermittency, skewness and flatness factors, correlations, scales, low-frequency spectra and convection velocity. The r.m.s. values of the various velocity fluctuations differ from those measured previously as a result of lack of self-preservation and insufficient frequency range in the instrumentation of the previous investigations. It appears that Taylor's hypothesis is not applicable to this flow, but the use of convection velocity of the appropriate scale for the transformation from temporal to spatial quantities appears appropriate. The energy balance was calculated from the various measured quantities and the result is quite different from the recent measurements of Sami (1967), which were obtained twenty diameters downstream from the nozzle. In light of these measurements some previous hypotheses about the turbulent structure and the transport phenomena are discussed. Some of the quantities were obtained by two or more different methods, and their relative merits and accuracy are assessed.

An adaptive digital filtering algorithm that can compensate for both frequency-selective multipath and interference on constant envelope modulated signals is presented. The method exploits the fact that multipath reception and various interference sources generate incidental amplitude modulation on the received signal. A class of so-called constant modulus performance functions is developed which sense this AM term but are insensitive to the angle modulation. Simple adaptive algorithms for finite-impulse-response (FIR) digital filters are developed which employ a gradient search of the performance function. One of the resulting algorithms is simulated for the example of an FM signal degraded by specular multipath propagation. Substantial improvements in noise power ratio (NPR) are observed (e.g., 25 dB) with moderately rapid convergence time. These results are then extended to include tonal interference on a FM signal and intersymbol interference on a QPSK data signal.

Implementation of backstepping becomes increasingly complex as the order of the system increases. This increasing complexity is mainly driven by the need to compute command derivatives at each step of the design, with the ultimate step requiring derivatives of the same order as the plant. This article addresses a modification that obviates the need to compute analytic derivatives by introducing command filters in the backstepping design. While the concept of the command filter has previously been introduced in the literature, the main contribution of this technical note is the rigorous analysis of the effect of the command filter on closed-loop stability and performance, and a proof of stability based on Tikhonov's theorem. The implementation approach includes a compensated tracking error that retains the standard stability properties of backstepping approaches.

High-resolution vanadium $K$-edge absorption spectra have been recorded for a number of selected vanadium compounds of known chemical structure with use of the synchrotron radiation available at the Stanford Synchrotron Radiation Laboratory (SSRL). The compounds studied include the oxides VO, ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$, ${\mathrm{V}}_{4}$${\mathrm{O}}_{7}$, ${\mathrm{V}}_{2}$${\mathrm{O}}_{4}$, and ${\mathrm{V}}_{2}$${\mathrm{O}}_{5}$; the vanadates ${\mathrm{NH}}_{4}$${\mathrm{VO}}_{3}$, ${\mathrm{CrVO}}_{4}$, and ${\mathrm{Pb}}_{5}$${({\mathrm{VO}}_{4})}_{3}$ Cl; the vanadyl compounds ${\mathrm{VOSO}}_{4}$.${3\mathrm{H}}_{2}$O, vanadyl bis(1-phenyl-1,3-butane) dionate, vanadyl phthalocyanine, and vanadyl tetraphenylporphyrin; the intermetallics VH, ${\mathrm{VB}}_{2}$, VC, VN, VP, and ${\mathrm{VSi}}_{2}$; and ${\mathrm{V}}_{2}$${\mathrm{S}}_{3}$ and a vanadium-bearing mineral, roscoelite. Vanadium in these compounds exhibits a wide range of formal oxidation states (0 to +5) and coordination geometries (octahedral, tetrahedral, square pyramid, etc.) with various ligands. The object of this systematic investigation is to gain further understanding of the details of various absorption features in the vicinity of the $K$ absorption edge of a constituent element in terms of its valence, site symmetry, coordination geometry, ligand type, and bond distances. In particular, the intensity and position of a well-defined pre-edged absorption in some of these compounds have been analyzed semiquantitatively within a molecular-orbital framework and a simple coordination-charge concept.

This paper presents the main objectives and a description of the SU2 suite, including the novel software architecture and open-source software engineering strategy. SU2 is a computational analysis and design package that has been developed to solve multiphysics analysis and optimization tasks using unstructured mesh topologies. Its unique architecture is well suited for extensibility to treat partial-differential-equation-based problems not initially envisioned. The common framework adopted enables the rapid implementation of new physics packages that can be tightly coupled to form a powerful ensemble of analysis tools to address complex problems facing many engineering communities. The framework is demonstrated on a number, solving both the flow and adjoint systems of equations to provide a high-fidelity predictive capability and sensitivity information that can be used for optimal shape design using a gradient-based framework, goal-oriented adaptive mesh refinement, or uncertainty quantification.

Implementation of adaptive backstepping controllers requires analytic calculation of the partial derivatives of certain stabilizing functions. It is well documented that, as the order of a nonlinear system increases, analytic calculation of these derivatives becomes prohibitive. Therefore, in practice, either alternative control approaches are used or the derivatives are neglected in the implementation. Neglecting the derivatives results in the loss of all guarantees proven by Lyapunov methods for the adaptive backstepping approach and may result in instability. This paper presents a new implementation approach for adaptive backstepping control. The main objectives are to facilitate the derivation and implementation of the adaptive backstepping approach, with performance guarantees proven by Lyapunov methods, for applications that were prohibitively difficult using the standard analytic implementation approach. The new approach uses filtering methods to produce certain command signals and their derivatives which eliminates the requirement of analytic differentiation. The approach also introduces filters to generate certain compensating signals necessary to compute compensated tracking errors suitable for adaptive parameter estimation. We present a set of Lemmas and Theorems to analyze the performance both during the initialization and the operating phases. We show that the initialization phase is of finite duration that can be controlled by selection of a design parameter. We also show that all signals within the system are bounded during this short initialization phase. During the operating phase, we show that the command filtered implementation approach has theoretical properties identical to those of the conventional approach. The general approach is presented and analyzed for systems in generalized parameter strict feedback form. Extensions of the approach are presented to demonstrate the application of the method to a land vehicle trajectory following application. Application and effectiveness of the proposed method is shown by simulation results.

We report the results of a Snell's law experiment on a negative index of refraction material in free space from 12.6 to 13.2 GHz. Numerical simulations using Maxwell's equations solvers show good agreement with the experimental results, confirming the existence of negative index of refraction materials. The index of refraction is a function of frequency. At 12.6 GHz we measure and compute the real part of the index of refraction to be -1.05. The measurements and simulations of the electromagnetic field profiles were performed at distances of 14lambda and 28lambda from the sample; the fields were also computed at 100lambda.

Fourier transforms of extended x-ray-absorption fine structure (EXAFS) give structural information in the vicinity of each kind of atom, separately, in a wide variety of gaseous, liquid, and solid systems. A detailed description of the analysis of EXAFS data is presented including details of the Fourier transform of the data and the extraction of structural and other physical parameters from these transforms. Included in this description are the measurement of interatomic distances, coordination numbers, disorder effects (thermal and structural), energy-dependent electron scattering amplitudes, inelastic mean free paths, and phase shifts. EXAFS spectra of Ge, Cu, and Ge${\mathrm{O}}_{2}$ are analyzed in detail. Multiple-scattering effects between atoms are generally found to be small. There are no multiple-scattering effects in the first shell of the Fourier transform. The phase shifts introduced by both the absorbing and surrounding atoms empirically appear to be characteristic of the particular atoms and independent of the surroundings for a given class of material. This is of great practical importance because it indicates that EXAFS can be calibrated by measuring known structures and then used to determine unknown ones.

The development of a wing/body/nacelle/pylon/horizontal-tail configuration for a common research model is presented, with focus on the aerodynamic design of the wing. Here, a contemporary transonic supercritical wing design is developed with aerodynamic characteristics that are well behaved and of high performance for configurations with and without the nacelle/pylon group. The horizontal tail is robustly designed for dive Mach number conditions and is suitably sized for typical stability and control requirements. The fuselage is representative of a wide/body commercial transport aircraft; it includes a wing-body fairing, as well as a scrubbing seal for the horizontal tail. The nacelle is a single-cowl, high by-pass-ratio, flow-through design with an exit area sized to achieve a natural unforced mass-flow-ratio typical of commercial aircraft engines at cruise. The simplicity of this un-bifurcated nacelle geometry will facilitate grid generation efforts of subsequent CFD validation exercises. Detailed aerodynamic performance data has been generated; however, this information is presented in such a manner as to not bias CFD predictions planned for the fourth AIAA CFD Drag Prediction Workshop (June 2009), which incorporates this common research model into its blind test cases. The CFD results presented include wing pressure distributions with and without the nacelle/pylon, ML/D trend lines, and drag-divergence curves; the design point for the wing/body configuration is within 1 % of its max-ML/D. Plans to test the common research model in

andsimplemathematicalfunctionshavingeasilyobservedphysicalfeatures.Thefundamentalparametricgeometry representation method is shown to describe an essentially limitless design space composed entirely of analytically smooth geometries. The class function/shape function methodology is then extended to more general threedimensional applications such as wing, body, ducts, and nacelles. It is shown that a general three-dimensional geometry can be represented by a distribution of fundamental shapes, and that the class function/shape function methodology can be used to describe the fundamental shapes as well as the distributions of the fundamental shapes. Withthisveryrobust,versatile,andsimplemethod, athree-dimensional geometry isdefinedinadesignspacebythe distribution of class functions and the shape functions. This design space geometry is then transformed into the physical space in which the actual geometry definition is obtained. A number of applications of the class function/ shape function transformation method to nacelles, ducts, wings, and bodies are presented to illustrate the versatility of this new methodology. It is shown that relatively few numbers of variables are required to represent arbitrary three-dimensional geometries such as an aircraft wing, nacelle, or body.

TheBoeingBlended-Wing–Body (BWB)airplane concept represents a potentialbreakthrough in subsonic trans-port ef ciency. Work began on this concept via a study to demonstrate feasibility and begin development of this new class of airplane. In this initial study, 800-passengerBWB and conventionalcon guration airplaneswere sized and compared for a 7000-n mile design range. Both airplanes were based on engine and structural (composite) technology for a 2010 entry into service. Results showed remarkable performance improvements of the BWB over the conventional baseline, including a 15 % reduction in takeoff weight and a 27 % reduction in fuel burn per seat mile. Subsequent in-house studies at Boeing have yielded the development of a family of BWB transports ranging from 200 to 600 passengers with a high level of parts commonality and manufacturing ef ciency. Studies have also demonstrated that the BWB is readily adaptable to cruise Mach numbers as high as 0.95. The performance improvement of the latest Boeing BWBs over conventional subsonic transports based on equivalent technologyhas increased beyond the predictions of the early NASA-sponsored studies. I.