Relevant bibliographies by topics / Computation of adjoints

Contents

  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
  6. Reports

Academic literature on the topic 'Computation of adjoints'

Author: Grafiati
Published: 4 June 2021
Last updated: 2 February 2022

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Computation of adjoints.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Journal articles on the topic "Computation of adjoints"

1

Larour, Eric, Jean Utke, Anton Bovin, Mathieu Morlighem, and Gilberto Perez. "An approach to computing discrete adjoints for MPI-parallelized models applied to Ice Sheet System Model 4.11." Geoscientific Model Development 9, no. 11 (November 1, 2016): 3907–18. http://dx.doi.org/10.5194/gmd-9-3907-2016.

Full text
Abstract:
Abstract. Within the framework of sea-level rise projections, there is a strong need for hindcast validation of the evolution of polar ice sheets in a way that tightly matches observational records (from radar, gravity, and altimetry observations mainly). However, the computational requirements for making hindcast reconstructions possible are severe and rely mainly on the evaluation of the adjoint state of transient ice-flow models. Here, we look at the computation of adjoints in the context of the NASA/JPL/UCI Ice Sheet System Model (ISSM), written in C++ and designed for parallel execution with MPI. We present the adaptations required in the way the software is designed and written, but also generic adaptations in the tools facilitating the adjoint computations. We concentrate on the use of operator overloading coupled with the AdjoinableMPI library to achieve the adjoint computation of the ISSM. We present a comprehensive approach to (1) carry out type changing through the ISSM, hence facilitating operator overloading, (2) bind to external solvers such as MUMPS and GSL-LU, and (3) handle MPI-based parallelism to scale the capability. We demonstrate the success of the approach by computing sensitivities of hindcast metrics such as the misfit to observed records of surface altimetry on the northeastern Greenland Ice Stream, or the misfit to observed records of surface velocities on Upernavik Glacier, central West Greenland. We also provide metrics for the scalability of the approach, and the expected performance. This approach has the potential to enable a new generation of hindcast-validated projections that make full use of the wealth of datasets currently being collected, or already collected, in Greenland and Antarctica.
APA, Harvard, Vancouver, ISO, and other styles
2

Hascoët, L., J. Utke, and U. Naumann. "Cheaper Adjoints by Reversing Address Computations." Scientific Programming 16, no. 1 (2008): 81–92. http://dx.doi.org/10.1155/2008/375243.

Full text
Abstract:
The reverse mode of automatic differentiation is widely used in science and engineering. A severe bottleneck for the performance of the reverse mode, however, is the necessity to recover certain intermediate values of the program in reverse order. Among these values are computed addresses, which traditionally are recovered through forward recomputation and storage in memory. We propose an alternative approach for recovery that uses inverse computation based on dependency information. Address storage constitutes a significant portion of the overall storage requirements. An example illustrates substantial gains that the proposed approach yields, and we show use cases in practical applications.
APA, Harvard, Vancouver, ISO, and other styles
3

BISCHOF, CHRISTIAN H., H. MARTIN BÜCKER, and PO-TING WU. "TIME-PARALLEL COMPUTATION OF PSEUDO-ADJOINTS FOR A LEAPFROG SCHEME." International Journal of High Speed Computing 12, no. 01 (June 2004): 1–27. http://dx.doi.org/10.1142/s0129053304000219.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Kohn, Kathlén, and Kristian Ranestad. "Projective Geometry of Wachspress Coordinates." Foundations of Computational Mathematics 20, no. 5 (November 11, 2019): 1135–73. http://dx.doi.org/10.1007/s10208-019-09441-z.

Full text
Abstract:
Abstract We show that there is a unique hypersurface of minimal degree passing through the non-faces of a polytope which is defined by a simple hyperplane arrangement. This generalizes the construction of the adjoint curve of a polygon by Wachspress (A rational finite element basis, Academic Press, New York, 1975). The defining polynomial of our adjoint hypersurface is the adjoint polynomial introduced by Warren (Adv Comput Math 6:97–108, 1996). This is a key ingredient for the definition of Wachspress coordinates, which are barycentric coordinates on an arbitrary convex polytope. The adjoint polynomial also appears both in algebraic statistics, when studying the moments of uniform probability distributions on polytopes, and in intersection theory, when computing Segre classes of monomial schemes. We describe the Wachspress map, the rational map defined by the Wachspress coordinates, and the Wachspress variety, the image of this map. The inverse of the Wachspress map is the projection from the linear span of the image of the adjoint hypersurface. To relate adjoints of polytopes to classical adjoints of divisors in algebraic geometry, we study irreducible hypersurfaces that have the same degree and multiplicity along the non-faces of a polytope as its defining hyperplane arrangement. We list all finitely many combinatorial types of polytopes in dimensions two and three for which such irreducible hypersurfaces exist. In the case of polygons, the general such curves are elliptic. In the three-dimensional case, the general such surfaces are either K3 or elliptic.
APA, Harvard, Vancouver, ISO, and other styles
5

Cacuci, Dan Gabriel. "First-Order Comprehensive Adjoint Method for Computing Operator-Valued Response Sensitivities to Imprecisely Known Parameters, Internal Interfaces and Boundaries of Coupled Nonlinear Systems: II. Application to a Nuclear Reactor Heat Removal Benchmark." Journal of Nuclear Engineering 1, no. 1 (September 9, 2020): 18–45. http://dx.doi.org/10.3390/jne1010003.

Full text
Abstract:
This work illustrates the application of a comprehensive first-order adjoint sensitivity analysis methodology (1st-CASAM) to a heat conduction and convection analytical benchmark problem which simulates heat removal from a nuclear reactor fuel rod. This analytical benchmark problem can be used to verify the accuracy of numerical solutions provided by software modeling heat transport and fluid flow systems. This illustrative heat transport benchmark shows that collocation methods require one adjoint computation for every collocation point while spectral expansion methods require one adjoint computation for each cardinal function appearing in the respective expansion when recursion relations cannot be developed between the corresponding adjoint functions. However, it is also shown that spectral methods are much more efficient when recursion relations provided by orthogonal polynomials make it possible to develop recursion relations for computing the corresponding adjoint functions. When recursion relations cannot be developed for the adjoint functions, the collocation method is probably more efficient than the spectral expansion method, since the sources for the corresponding adjoint systems are just Dirac delta functions (which makes the respective computation equivalent to the computation of a Green’s function), rather than the more elaborated sources involving high-order Fourier basis functions or orthogonal polynomials. For systems involving many independent variables, it is likely that a hybrid combination of spectral expansions in some independent variables and collocation in the remaining independent variables would provide the most efficient computational outcome.
APA, Harvard, Vancouver, ISO, and other styles
6

Capps, S. L., D. K. Henze, A. Hakami, A. G. Russell, and A. Nenes. "ANISORROPIA: the adjoint of the aerosol thermodynamic model ISORROPIA." Atmospheric Chemistry and Physics Discussions 11, no. 8 (August 19, 2011): 23469–511. http://dx.doi.org/10.5194/acpd-11-23469-2011.

Full text
Abstract:
Abstract. We present the development of ANISORROPIA, the discrete adjoint of the ISORROPIA thermodynamic equilibrium model that treats the Na+-SO42−-HSO4−-NH4+-NO3−-Cl−-H2O aerosol system, and we demonstrate its sensitivity analysis capabilities. ANISORROPIA calculates sensitivities of an inorganic species in aerosol or gas phase with respect to the total concentrations of each species present with only a two-fold increase in computational time over the forward model execution. Due to the highly nonlinear and discontinuous solution surface of ISORROPIA, evaluation of the adjoint required a new, complex-variable version of the the model, which determines first-order sensitivities with machine precision and avoids cancellation errors arising from finite difference calculations. The adjoint is verified over an atmospherically relevant range of concentrations, temperature, and relative humidity. We apply ANISORROPIA to recent field campaign results from Atlanta, GA, USA, and Mexico City, Mexico, to characterize the inorganic aerosol sensitivities of these distinct urban air masses. The variability in the relationship between PM2.5 mass and precursor concentrations shown has important implications for air quality and climate. ANISORROPIA enables efficient elucidation of aerosol concentration dependence on aerosol precursor emissions in the context of atmospheric chemical transport model adjoints.
APA, Harvard, Vancouver, ISO, and other styles
7

Ito, Shin-ichi, Takeru Matsuda, and Yuto Miyatake. "Adjoint-based exact Hessian computation." BIT Numerical Mathematics 61, no. 2 (February 17, 2021): 503–22. http://dx.doi.org/10.1007/s10543-020-00833-0.

Full text
Abstract:
AbstractWe consider a scalar function depending on a numerical solution of an initial value problem, and its second-derivative (Hessian) matrix for the initial value. The need to extract the information of the Hessian or to solve a linear system having the Hessian as a coefficient matrix arises in many research fields such as optimization, Bayesian estimation, and uncertainty quantification. From the perspective of memory efficiency, these tasks often employ a Krylov subspace method that does not need to hold the Hessian matrix explicitly and only requires computing the multiplication of the Hessian and a given vector. One of the ways to obtain an approximation of such Hessian-vector multiplication is to integrate the so-called second-order adjoint system numerically. However, the error in the approximation could be significant even if the numerical integration to the second-order adjoint system is sufficiently accurate. This paper presents a novel algorithm that computes the intended Hessian-vector multiplication exactly and efficiently. For this aim, we give a new concise derivation of the second-order adjoint system and show that the intended multiplication can be computed exactly by applying a particular numerical method to the second-order adjoint system. In the discussion, symplectic partitioned Runge–Kutta methods play an essential role.
APA, Harvard, Vancouver, ISO, and other styles
8

Boehm, Christian, Mauricio Hanzich, Josep de la Puente, and Andreas Fichtner. "Wavefield compression for adjoint methods in full-waveform inversion." GEOPHYSICS 81, no. 6 (November 2016): R385—R397. http://dx.doi.org/10.1190/geo2015-0653.1.

Full text
Abstract:
Adjoint methods are a key ingredient of gradient-based full-waveform inversion schemes. While being conceptually elegant, they face the challenge of massive memory requirements caused by the opposite time directions of forward and adjoint simulations and the necessity to access both wavefields simultaneously for the computation of the sensitivity kernel. To overcome this bottleneck, we have developed lossy compression techniques that significantly reduce the memory requirements with only a small computational overhead. Our approach is tailored to adjoint methods and uses the fact that the computation of a sufficiently accurate sensitivity kernel does not require the fully resolved forward wavefield. The collection of methods comprises reinterpolation with a coarse temporal grid as well as adaptively chosen polynomial degree and floating-point precision to represent spatial snapshots of the forward wavefield on hierarchical grids. Furthermore, the first arrivals of adjoint waves are used to identify “shadow zones” that do not contribute to the sensitivity kernel. Numerical experiments show the high potential of this approach achieving an effective compression factor of three orders of magnitude with only a minor reduction in the rate of convergence. Moreover, it is computationally cheap and straightforward to integrate in finite-element wave propagation codes with possible extensions to finite-difference methods.
APA, Harvard, Vancouver, ISO, and other styles
9

Guerrette, J. J., and D. K. Henze. "Development and application of the WRFPLUS-Chem online chemistry adjoint and WRFDA-Chem assimilation system." Geoscientific Model Development Discussions 8, no. 2 (February 27, 2015): 2313–67. http://dx.doi.org/10.5194/gmdd-8-2313-2015.

Full text
Abstract:
Abstract. Here we present the online meteorology and chemistry adjoint and tangent linear model, WRFPLUS-Chem, which incorporates modules to treat boundary layer mixing, emission, aging, dry deposition, and advection of black carbon aerosol. We also develop land surface and surface layer adjoints to account for coupling between radiation and vertical mixing. Model performance is verified against finite difference derivative approximations. A second order checkpointing scheme is created to reduce computational costs and enable simulations longer than six hours. The adjoint is coupled to WRFDA-Chem, in order to conduct a sensitivity study of anthropogenic and biomass burning sources throughout California during the 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) field campaign. A cost function weighting scheme was devised to increase adjoint sensitivity robustness in future inverse modeling studies. Results of the sensitivity study show that, for this domain and time period, anthropogenic emissions are over predicted, while wildfire emissions are under predicted. We consider the diurnal variation in emission sensitivities to determine at what time sources should be scaled up or down. Also, adjoint sensitivities for two choices of land surface model indicate that emission inversion results would be sensitive to forward model configuration. The tools described here are the first step in conducting four-dimensional variational data assimilation in a coupled meteorology-chemistry model, which will potentially provide new constraints on aerosol precursor emissions and their distributions. Such analyses will be invaluable to assessments of particulate matter health and climate impacts.
APA, Harvard, Vancouver, ISO, and other styles
10

Akbarzadeh, Siamak, Jan Hückelheim, and Jens-Dominik Müller. "Consistent treatment of incompletely converged iterative linear solvers in reverse-mode algorithmic differentiation." Computational Optimization and Applications 77, no. 2 (August 3, 2020): 597–616. http://dx.doi.org/10.1007/s10589-020-00214-x.

Full text
Abstract:
Abstract Algorithmic differentiation (AD) is a widely-used approach to compute derivatives of numerical models. Many numerical models include an iterative process to solve non-linear systems of equations. To improve efficiency and numerical stability, AD is typically not applied to the linear solvers. Instead, the differentiated linear solver call is replaced with hand-produced derivative code that exploits the linearity of the original call. In practice, the iterative linear solvers are often stopped prematurely to recompute the linearisation of the non-linear outer loop. We show that in the reverse-mode of AD, the derivatives obtained with partial convergence become inconsistent with the original and the tangent-linear models, resulting in inaccurate adjoints. We present a correction term that restores consistency between adjoint and tangent-linear gradients if linear systems are only partially converged. We prove the consistency of this correction term and show in numerical experiments that the accuracy of adjoint gradients of an incompressible flow solver applied to an industrial test case is restored when the correction term is used.
APA, Harvard, Vancouver, ISO, and other styles
More sources

Dissertations / Theses on the topic "Computation of adjoints"

1

Walther, Andrea. "Discrete Adjoints: Theoretical Analysis, Efficient Computation, and Applications." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1214221752009-12115.

Full text
Abstract:
The technique of automatic differentiation provides directional derivatives and discrete adjoints with working accuracy. A complete complexity analysis of the basic modes of automatic differentiation is available. Therefore, the research activities are focused now on different aspects of the derivative calculation, as for example the efficient implementation by exploitation of structural information, studies of the theoretical properties of the provided derivatives in the context of optimization problems, and the development and analysis of new mathematical algorithms based on discrete adjoint information. According to this motivation, this habilitation presents an analysis of different checkpointing strategies to reduce the memory requirement of the discrete adjoint computation. Additionally, a new algorithm for computing sparse Hessian matrices is presented including a complexity analysis and a report on practical experiments. Hence, the first two contributions of this thesis are dedicated to an efficient computation of discrete adjoints. The analysis of discrete adjoints with respect to their theoretical properties is another important research topic. The third and fourth contribution of this thesis focus on the relation of discrete adjoint information and continuous adjoint information for optimal control problems. Here, differences resulting from different discretization strategies as well as convergence properties of the discrete adjoints are analyzed comprehensively. In the fifth contribution, checkpointing approaches that are successfully applied for the computation of discrete adjoints, are adapted such that they can be used also for the computation of continuous adjoints. Additionally, the fifth contributions presents a new proof of optimality for the binomial checkpointing that is based on new theoretical results. Discrete adjoint information can be applied for example for the approximation of dense Jacobian matrices. The development and analysis of new mathematical algorithms based on these approximate Jacobians is the topic of the sixth contribution. Is was possible to show global convergence to first-order critical points for a whole class of trust-region methods. Here, the usage of inexact Jacobian matrices allows a considerable reduction of the computational complexity.
APA, Harvard, Vancouver, ISO, and other styles
2

Walther, Andrea. "Discrete Adjoints: Theoretical Analysis, Efficient Computation, and Applications." Doctoral thesis, Technische Universität Dresden, 2007. https://tud.qucosa.de/id/qucosa%3A23715.

Full text
Abstract:
The technique of automatic differentiation provides directional derivatives and discrete adjoints with working accuracy. A complete complexity analysis of the basic modes of automatic differentiation is available. Therefore, the research activities are focused now on different aspects of the derivative calculation, as for example the efficient implementation by exploitation of structural information, studies of the theoretical properties of the provided derivatives in the context of optimization problems, and the development and analysis of new mathematical algorithms based on discrete adjoint information. According to this motivation, this habilitation presents an analysis of different checkpointing strategies to reduce the memory requirement of the discrete adjoint computation. Additionally, a new algorithm for computing sparse Hessian matrices is presented including a complexity analysis and a report on practical experiments. Hence, the first two contributions of this thesis are dedicated to an efficient computation of discrete adjoints. The analysis of discrete adjoints with respect to their theoretical properties is another important research topic. The third and fourth contribution of this thesis focus on the relation of discrete adjoint information and continuous adjoint information for optimal control problems. Here, differences resulting from different discretization strategies as well as convergence properties of the discrete adjoints are analyzed comprehensively. In the fifth contribution, checkpointing approaches that are successfully applied for the computation of discrete adjoints, are adapted such that they can be used also for the computation of continuous adjoints. Additionally, the fifth contributions presents a new proof of optimality for the binomial checkpointing that is based on new theoretical results. Discrete adjoint information can be applied for example for the approximation of dense Jacobian matrices. The development and analysis of new mathematical algorithms based on these approximate Jacobians is the topic of the sixth contribution. Is was possible to show global convergence to first-order critical points for a whole class of trust-region methods. Here, the usage of inexact Jacobian matrices allows a considerable reduction of the computational complexity.
APA, Harvard, Vancouver, ISO, and other styles
3

Amoignon, Olivier. "Adjoint-based aerodynamic shape optimization." Licentiate thesis, Uppsala universitet, Avdelningen för teknisk databehandling, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-86142.

Full text
Abstract:
An adjoint system of the Euler equations of gas dynamics is derived in order to solve aerodynamic shape optimization problems with gradient-based methods. The derivation is based on the fully discrete flow model and involves differentiation and transposition of the system of equations obtained by an unstructured and node-centered finite-volume discretization. Solving the adjoint equations allows an efficient calculation of gradients, also when the subject of optimization is described by hundreds or thousands of design parameters. Such a fine geometry description may cause wavy or otherwise irregular designs during the optimization process. Using the one-to-one mapping defined by a Poisson problem is a known technique that produces smooth design updates while keeping a fine resolution of the geometry. This technique is extended here to combine the smoothing effect with constraints on the geometry, by defining the design updates as solutions of a quadratic programming problem associated with the Poisson problem. These methods are applied to airfoil shape optimization for reduction of the wave drag, that is, the drag caused by gas dynamic effects that occur close to the speed of sound. A second application concerns airfoil design optimization to delay the laminar-to-turbulent transition point in the boundary layer in order to reduce the drag. The latter application has been performed by the author with collaborators, also using gradient-based optimization. Here, the growth of convectively unstable disturbances are modeled by successively solving the Euler equations, the boundary layer equations, and the parabolized stability equations.
APA, Harvard, Vancouver, ISO, and other styles
4

Carmelid, Simon. "Calibrating the Hull-White model using Adjoint Algorithmic Differentiation." Thesis, KTH, Matematisk statistik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-214031.

Full text
Abstract:
This thesis includes a brief introduction to Adjoint Algorithmic Differentiation (AAD), accompanied by numerical examples, step-by-step explanations and runtime comparisons to a finite difference method. In order to show the applicability of AAD in a stochastic setting, it is also applied in the calculation of the arbitrage free price and partial derivatives of a European call option, where the underlying stock has Geometric Brownian motion dynamics. Finally the Hull-White model is calibrated using a set of zero coupon bonds, and a set of swaptions. Using AAD, the partial derivatives of the model are found and used in a Newton-Raphson method in order to find the market's implied volatility. The end result is a Monte Carlo simulated short rate curve and its derivatives with respect to the calibration parameters, i.e. the zero coupon bond and swaption prices.
Denna uppsats innehåller en introduktion till Adjungerad Algoritmisk Differentiering (AAD), tillsammans med numeriska exempel, steg-för-steg beskrivningar samt körtidsjämförelser med en finit differensmetod. För att illustrera applicerbarheten av AAD i ett stokastiskt ramverk, tillämpas metoden i beräkningen av det arbitragefria priset och de partiella derivatorna av en europeisk köp-option, där den underliggande aktien har geometrisk Brownsk dynamik. Slutligen kalibreras Hull-White-modellen genom ett antal nollkupongsobligationer och swap-optioner. Via AAD beräknas de partiella derivatorna för modellen som sedan används i Newton-Raphsons metod för att finna markandens implicita volatilitet. Slutresultatet är en Monte Carlo-simulerad räntekurva och dess derivator med avseende på kalibreringsparametrarna, dvs. nollkupongs- och swap-optionspriserna.
APA, Harvard, Vancouver, ISO, and other styles
5

Davis, Andrew D. (Andrew Donaldson). "Multi-parameter estimation in glacier models with adjoint and algorithmic differentiation." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/72868.

Full text
Abstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Computation for Design and Optimization Program, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 75-77).
The cryosphere is comprised of about 33 million km³ of ice, which corresponds to 70 meters of global mean sea level equivalent [30]. Simulating continental ice masses, such as the Antarctic or Greenland Ice Sheets, requires computational models capturing abrupt changes in ice sheet dynamics, which are still poorly understood. Input parameters, such as basal drag and topography, have large effects on the applied stress and flow fields but whose direct observation is very difficult, if not impossible. Computational methods are designed to aid in the development of ice sheet models, ideally identifying the relative importance of each parameter and formulating inverse methods to infer uncertain parameters and thus constrain ice sheet flow. Efficient computation of the tangent linear and adjoint models give researchers easy access to model derivatives. The adjoint and tangent linear models enable efficient global sensitivity computation and parameter optimization on unknown or uncertain ice sheet properties, information used to identify model properties having large effects on sea-level. The adjoint equations are not always easily obtained analytically and often require discretizing additional PDE's. Algorithmic differentiation (AD) decomposes the model into a composite of elementary operations (+, -, *, /, etc ... ) and a source-to-source transformation generates code for the Jacobian and its transpose for each operations. Derivatives computed using the tangent linear and adjoint models, with code generated by AD, are applied to parameter estimation and sensitivity analysis of simple glacier models. AD is applied to two examples, equations describing changes in borehole temperature over time and instantaneous ice velocities. Borehole model predictions and data are compared to infer paleotemperatures, geothermal heat flux, and physical ice properties. Inversion using adjoint methods and AD increases the control space, allowing inference for all uncertain parameters. The sensitivities of ice velocities to basal friction and basal topography are compared. The basal topography has significantly larger sensitivities, suggesting it plays a larger role in flow dynamics and future work should seek to invert for this parameter.
by Andrew D. Davis.
S.M.
APA, Harvard, Vancouver, ISO, and other styles
6

Schneider, Rene. "Applications of the discrete adjoint method in computational fluid dynamics." Thesis, University of Leeds, 2006. http://etheses.whiterose.ac.uk/1343/.

Full text
Abstract:
The discrete adjoint method allows efficient evaluation of the derivative of a function I(s) with respect to parameters s in situations where I depends on s indirectly, via an intermediate variable w(s), which is computationally expensive to evaluate. In this thesis two applications of this method in the context of computational fluid dynamics are considered. The first is shape optimisation, where the discrete adjoint approach is employed to compute the derivatives with respect to shape parameters for a performance functional depending on the solution of a mathematical flow model which has the form of a discretised system of partial differential equations. In this context particular emphasis is given to efficient solution strategies for the linear systems arising in the discretisation of the flow models. Numerical results for two example problems are presented, demonstrating the utility of the approach. The second application, in adaptive mesh design, allows efficient evaluation of the derivatives of an a posteriori error estimate with respect to the positions of the nodes in a finite element mesh. This novel approach makes additional information available which may be utilised to guide the automatic design of adaptive meshes. Special emphasis is given to problems with anisotropic solution features, for which adaptive anisotropic mesh refinement can deliver significant performance improvements over existing adaptive hrefinement approaches. Two adaptive solution algorithms are presented and compared to existing approaches by applying them to a reaction-diffusion model problem.
APA, Harvard, Vancouver, ISO, and other styles
7

Moret-Gabarro, Laia. "Aeroacoustic investigation and adjoint analysis of subsonic cavity flows." Thesis, Toulouse, INPT, 2009. http://www.theses.fr/2009INPT047H/document.

Full text
Abstract:
Les écoulements instationnaires au-dessus de surfaces discontinues produisent d'important bruit aérodynamique. L'objectif de ce travail de thèse est l'étude aéroacoustique d'écoulement au-dessus de cavités bidimensionnelles rectangulaires, et de trouver des stratégies de réduction du bruit. Des simulations numériques directes des équations bidimensionnelles de Navier-Stokes compressibles ont été réalisées afin d'étudier l'influence des conditions initiales sur le mode d'oscillation de l'écoulement pour des cavités profonde et peu profonde. Les résultats montrent que dans le cas de cavités profondes, l'écoulement oscille selon un régime de couche de cisaillement suivant le second mode de Rossiter, et ce quelle que soit la condition initiale choisie. En revanche, dans le cas de cavités peu profondes, le régime d'oscillation observé peut être en couche de cisaillement ou bien en mode de sillage suivant la condition initiale choisie. Une analyse de sensibilité d'écoulement dans le cas de cavités profondes a été réalisé en utilisant une méthode adjointe. Les équations adjointes ont été forcées par une perturbation localisée sinusoïdale soit de la quantité de mouvement suivant x adjointe (au voisinage de la couche de cisaillement), soit de la densité adjointe (loin de la cavité). Les résultats désignent une région de l'écoulement très sensible à l'ajout de masse, et localisée au voisinage du coin supérieur amont de la cavité. Par conséquent, un actionneur de type soufflage/aspiration placé au bord d'attaque de la cavité agira sur les fluctuations de quantité de mouvement suivant x au voisinage de la couche de cisaillement et sur les fluctuations de pression au loin
The unsteady flow over surface discontinuities produces high aerodynamic noise. The aim of this thesis is to study the aeroacoustics of two-dimensional rectangular cavities and to find strategies for noise reduction. Direct Numerical Simulation of the compressible Navier-Stokes equations is performed to investigate the influence of the initial condition on the oscillation modes in deep and shallow cavities. Results show that the deep cavity oscillates in shear layer regime at the second Rossiter mode regardless of the initial condition. On the other hand different initial conditions lead to a shear layer or wake mode in the shallow cavity case. A sensitivity analysis of the deep cavity is done by the use of adjoint methods. Local sinusoidal perturbations of x-momentum and density are applied to the adjoint equations. The results show a high sensitivity region to mass injection at the upstream corner. Therefore an actuator placed at the leading edge will modify the velocity fluctuations reaching the trailing edge and hence the pressure fluctuations in the far-field
APA, Harvard, Vancouver, ISO, and other styles
8

Christakopoulos, Faidon. "Sensitivity computation and shape optimisation in aerodynamics using the adjoint methodology and Automatic Differentiation." Thesis, Queen Mary, University of London, 2012. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8379.

Full text
Abstract:
Adjoint based optimisation has until now demonstrated a great promise for optimisation in aerodynamics due to its independence of the number of design variables. This is essential in large industrial applications, where hundreds of parameters might be needed so as to describe the geometry. Although the computational cost of the methodology is smaller than that of stochastic optimisation methods, the implementation and related program maintenance time and effort could be particularly high. The aim of the present is to contribute to the effort of redusing the cost above by examining whether programs using the adjoint methodology for optimisation can be automatically generated and maintained via Automatic Differentiation, while presenting comparable performance to hand derived adjoints. This could lead to accurate adjoint based optimisation codes, which would inherit any change or addition to the relative original Computational Fluid Dynamics code. Such a methodology is presented and all the different steps involved are detailed. It is found that although a considerable initial effort is required for preparation of the source code for differentiation, hand assembly of the sensitivity algorithms and scripting for the automation of the entire process, the target of this research program is achieved and fully automatically generated adjoint codes with comparable performance can be acquired. After applying the methodology to a number of aerodynamic shape optimisation examples, the logic is also extended to higher derivatives, which could also be included in the optimisation process for robust design.
APA, Harvard, Vancouver, ISO, and other styles
9

Thompson, Peter Mark. "Computation of CAD-based design velocities for aerodynamic design optimisation with adjoint CFD data." Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.675476.

Full text
Abstract:
This thesis describes the investigation and development of a novel CAD-based aerodynamic optimisation system, with the aim of allowing gradient-based optimisation of feature-based, parametric models within commercial CAD packages in timescales acceptable for industrial design processes. The process developed is based on linking parametric design velocities (geometric sensitivities computed from the CAD model representing the displacement of a point on the model boundary due to a perturbation of a CAD model parameter) with adjoint surface mesh sensitivities (which represent the derivative of a goal function with respect to surface mesh node position). A CAD-based design velocity computation method has been developed based on projection between discrete representations of perturbed geometries which can be linked to virtually any existing commercial CAD system. A key characteristic of the approach is that it can cope with the discontinuous changes in CAD model topology and face labelling that can occur under even small changes in CAD parameters. Use of the above approach allows computation of parametric sensitivities with respect to aerodynamic coefficients for native CAD parameters within feature-based commercial CAD modelling systems using adjoint data at a computational cost of just one adjoint analysis per objective function and one design velocity field evaluation per parameter. Gradient computation is demonstrated on test cases for an aerofoil model, a turbine blade model and a 3D wing model. Using these computed sensitivities enables the creation of a truly CAD-based aerodynamic optimisation system incorporating adjoint CFD data and using design velocities for computing geometric sensitivities and as input to a mesh deformation step. A prototype implementation of this system is presented and used to optimise a parametric CAD-based aerofoil model. In order to develop the approach further, future work should focus on resolving issues encountered when using design velocities for mesh deformation, extending the approach to more complex test cases, and potentially incorporating parametric effectiveness as a measure of the suitability of a given CAD parameterisation for optimisation purposes.
APA, Harvard, Vancouver, ISO, and other styles
10

Koo, Jamin. "Adjoint sensitivity analysis of the intercontinental impacts of aviation emissions on air quality and health." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/72936.

Full text
Abstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Computation for Design and Optimization Program, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 75-79).
Over 10,000 premature mortalities per year globally are attributed to the exposure to particulate matter caused by aircraft emissions. Unlike previous studies that focus on the regional impacts from the aircraft emissions below 3,000 feet, this thesis studies the impact from emissions at all altitudes and across continents on increasing particulates in a receptor region, thereby increasing exposure. In addition to these intercontinental impacts, the thesis analyzes the temporal variations of sensitivities of the air quality and health, the proportion of the impacts attributable to different emission species, and the background emissions' influence on the impact of aircraft emissions. To quantify the impacts of aircraft emissions at various locations and times, this study uses the adjoint model of GEOS-Chem, a chemical transport model. The adjoint method efficiently computes sensitivities of a few objective functions, such as aggregated PM concentration and human exposure to PM concentration, with respect to many input parameters, i.e. emissions at different locations and times. Whereas emissions below 3,000 feet have mostly local impacts, cruise emissions from North America impair the air quality in Europe and Asia, and European cruise emissions affect Asia. Due to emissions entering Asia, the premature mortalities in Asia were approximately two to three times larger than the global mortalities caused by the Asian emissions. In contrast, North America observed only about one-ninth of the global premature mortalities caused by North American emissions because emissions get carried out of the region. This thesis calculates that most of the premature mortalities occured in Europe and Asia in 2006. Sensitivities to emissions also have seasonal and diurnal cycles. For example, ground level NOx emissions in the evening contribute to 50% more surface PM formation than the same emissions in the morning, and cruise level NOx emissions in early winter cause six times more PM concentration increase than the same emissions in spring. Aircraft NOx emissions cause 78% of PM from aviation emissions, and given the population exposure to PM concentration increase, NOx contributes 90% of the total impact. By showing the second-order sensitivities, this study finds that increases in background emissions of ammonia increase the impact of aircraft emissions on the air quality and increases in background NOx emissions decrease the impact. These results show the effectiveness of the adjoint model for analyzing the longterm sensitivities. Some of the analyses presented are practically only possible with the adjoint method. By regulating emissions at high sensitivities in time and region, calculated by the adjoint model, governments can design effective pollutant reduction policies.
by Jamin Koo.
S.M.
APA, Harvard, Vancouver, ISO, and other styles
More sources

Books on the topic "Computation of adjoints"

1

Schmüdgen, Konrad. Unbounded Self-adjoint Operators on Hilbert Space. Dordrecht: Springer Netherlands, 2012.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
2

Anderson, W. Kyle. Aerodynamic design optimization on unstructured grids with a continuous adjoint formulation. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1997.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
3

Numerical computation of sensitivities and the adjoint approach. Hampton, VA: Institute for Computer Applications in Science and Engineering, NASA Langley Research Center, 1997.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
4

Schmüdgen, Konrad. Unbounded Self-adjoint Operators on Hilbert Space. Springer, 2012.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
5

V, Venkatakrishnan, and Langley Research Center, eds. Aerodynamic design optimization on unstructured grids with a continuous adjoint formulation. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1997.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
6

Engeli. Refined Iterative Methods for Computation of the Solution and the Eigenvalues of Self-Adjoint Boundary Value Problems. Springer, 2012.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
7

ENGELI, GINSBURG, and STIEFEL. Refined Iterative Methods for Computation of the Solution and the Eigenvalues of Self-Adjoint Boundary Value Problems. Birkhäuser, 2012.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
8

1934-, Jameson Antony, and Research Institute for Advanced Computer Science (U.S.), eds. Supersonic wing and wing-body shape optimization using an adjoint formulation. [Moffett Field, Calif.]: Research Institute for Advanced Computer Science, NASA Ames Research Center, 1995.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
9

1934-, Jameson Antony, and Research Institute for Advanced Computer Science (U.S.), eds. Supersonic wing and wing-body shape optimization using an adjoint formulation. [Moffett Field, Calif.]: Research Institute for Advanced Computer Science, NASA Ames Research Center, 1995.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
10

1934-, Jameson Antony, and Research Institute for Advanced Computer Science (U.S.), eds. Supersonic wing and wing-body shape optimization using an adjoint formulation. [Moffett Field, Calif.]: Research Institute for Advanced Computer Science, NASA Ames Research Center, 1995.

Find full text
APA, Harvard, Vancouver, ISO, and other styles

Book chapters on the topic "Computation of adjoints"

1

Bockhorn, Arne, Sri Hari Krishna Narayanan, and Andrea Walther. "Checkpointing Approaches for the Computation of Adjoints Covering Resilience Issues." In 2020 Proceedings of the SIAM Workshop on Combinatorial Scientific Computing, 22–31. Philadelphia, PA: Society for Industrial and Applied Mathematics, 2020. http://dx.doi.org/10.1137/1.9781611976229.3.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Akritas, Alkiviadis, and Gennadi Malaschonok. "Computation of the Adjoint Matrix." In Computational Science – ICCS 2006, 486–89. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/11758525_65.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Krawczak, Maciej. "Adjoint Neural Networks." In Studies in Computational Intelligence, 145–66. Heidelberg: Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-00248-4_7.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Mac Lane, Saunders. "The Lambda Calculus and Adjoint Functors." In Logic, Meaning and Computation, 181–84. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-010-0526-5_7.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Giles, Michael B. "Defect and Adjoint Error Correction." In Computational Fluid Dynamics 2000, 28–36. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56535-9_3.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Cornejo, Ma Eugenia, Jesús Medina, and Eloisa Ramírez. "Implication Triples versus Adjoint Triples." In Advances in Computational Intelligence, 453–60. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-21498-1_57.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Beckers, Markus, Viktor Mosenkis, and Uwe Naumann. "Adjoint Mode Computation of Subgradients for McCormick Relaxations." In Lecture Notes in Computational Science and Engineering, 103–13. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-30023-3_10.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Lewis, Robert Michael. "Numerical Computation of Sensitivities and the Adjoint Approach." In Computational Methods for Optimal Design and Control, 285–302. Boston, MA: Birkhäuser Boston, 1998. http://dx.doi.org/10.1007/978-1-4612-1780-0_16.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Sandu, Adrian. "On the Properties of Runge-Kutta Discrete Adjoints." In Computational Science – ICCS 2006, 550–57. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/11758549_76.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

McClarren, Ryan G. "Adjoint-Based Local Sensitivity Analysis." In Uncertainty Quantification and Predictive Computational Science, 129–43. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-99525-0_6.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Conference papers on the topic "Computation of adjoints"

1

Gottschalk, Hanno, Mohamed Saadi, Onur Tanil Doganay, Kathrin Klamroth, and Sebastian Schmitz. "Adjoint Method to Calculate the Shape Gradients of Failure Probabilities for Turbomachinery Components." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-75759.

Full text
Abstract:
In the optimization of turbomachinery components, shape sensitivities for fluid dynamical objective functions have been used for a long time. As peak stress is not a differential functional of the shape, such highly efficient procedures so far have been missing for objective functionals that stem from mechanical integrity. This changes, if deterministic lifing criteria are replaced by probabilistic criteria, which have been introduced recently to the field of low cycle fatigue (LCF). Here we present a finite element (FEA) based first discretize, then adjoin approach to the calculation of shape gradients (sensitivities) for the failure probability with regard to probabilistic LCF and apply it to simple and complex geometries, as e.g. a blisk geometry. We review the computation of failure probabilities with a FEA postprocessor and sketch the computation of the relevant quantities for the adjoint method. We demonstrate high accuracy and computational efficiency of the adjoint method compared to finite difference schemes. We discuss implementation details for rotating components with cyclic boundary conditions. Finally, we shortly comment on future development steps and on potential applications in multi criteria optimization.
APA, Harvard, Vancouver, ISO, and other styles
2

Nguyen, Tuyan V., Anirudh Devgan, and Ognen J. Nastov. "Adjoint transient sensitivity computation in piecewise linear simulation." In the 35th annual conference. New York, New York, USA: ACM Press, 1998. http://dx.doi.org/10.1145/277044.277177.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Huang, Jianzhe. "Real-Time Simulation of Unmanned Rotorcraft With Ground Effect Through Adjoint Theorem." In ASME 2019 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/detc2019-98313.

Full text
Abstract:
Abstract Unmamned rotorcraft requires automatic control system to adjust transient flight behaviors properly, and real-time computation of aerodynamic forces is also in demand. Finite-state inflow model is one of the most efficient models which can fulfill such a requirement. When a rotorcraft is flying close to ground, a strong downwash impinges on the ground surface and reflected airstream influences the flow field of the main rotor. Such a physical phenomenon makes the aerodynamic computations complex, and previous studies have solved such a problem by simulation ground effect with a ground rotor. But it still requires numerical integration to compute the flow field of main rotor downstream, and the computational efficiency degrades evidently. In this paper, adjoint theorem is proposed to calculate induced velocity in the rotor wake with closed form equations. The hover and forward flight conditions will be examined for different moment of inertia of blade and forward flight speeds.
APA, Harvard, Vancouver, ISO, and other styles
4

Duraisamy, Karthikeyan, Juan Alonso, and Praveen Chandrashekar. "Goal Oriented Uncertainty Propagation using Stochastic Adjoints." In 20th AIAA Computational Fluid Dynamics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2011. http://dx.doi.org/10.2514/6.2011-3412.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Ganapati, Vidya, Laura Waller, and Eli Yablonovitch. "Adjoint Method for Phase Retrieval." In Computational Optical Sensing and Imaging. Washington, D.C.: OSA, 2014. http://dx.doi.org/10.1364/cosi.2014.cw4c.2.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Awotunde, Abeeb Adebowale, and Roland N. Horne. "An Improved Adjoint Sensitivity Computation for Multiphase Flow Using Wavelets." In SPE Annual Technical Conference and Exhibition. Society of Petroleum Engineers, 2010. http://dx.doi.org/10.2118/133866-ms.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Statz, Christoph, Marco Mutze, Sebastian Hegler, and Dirk Plettemeier. "Hybrid CPU-GPU computation of adjoint derivatives in time domain." In 2013 Computational Electromagnetics Workshop (CEM'13). IEEE, 2013. http://dx.doi.org/10.1109/cem.2013.6617123.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Albertin, Uwe. "An improved gradient computation for adjoint wave‐equation reflection tomography." In SEG Technical Program Expanded Abstracts 2011. Society of Exploration Geophysicists, 2011. http://dx.doi.org/10.1190/1.3628034.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Ikeda, Tomoya, Shin-ichi Ito, Hiromichi Nagao, Takahiro Katagiri, Toru Nagai, and Masao Ogino. "Optimizing Forward Computation in Adjoint Method via Multi-level Blocking." In HPC Asia 2018: International Conference on High Performance Computing in Asia-Pacific Region. New York, NY, USA: ACM, 2018. http://dx.doi.org/10.1145/3149457.3149458.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Lapointe, Caelan, Jason D. Christopher, Nicholas T. Wimer, Torrey R. Hayden, Gregory B. Rieker, and Peter E. Hamlington. "Optimization for Internal Turbulent Compressible Flows Using Adjoints." In 23rd AIAA Computational Fluid Dynamics Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2017. http://dx.doi.org/10.2514/6.2017-4115.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Reports on the topic "Computation of adjoints"

1

Abhyankar, Shrirang, Mihai Anitescu, Emil Constantinescu, and Hong Zhang. Efficient Adjoint Computation of Hybrid Systems of Differential Algebraic Equations with Applications in Power Systems. Office of Scientific and Technical Information (OSTI), March 2016. http://dx.doi.org/10.2172/1245175.

Full text
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the extended bibliographies on the topic 'Computation of adjoints' for particular source types:
Journal articles Dissertations / Theses
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography