Review of ankle inversion sprain simulators in the biomechanics laboratory

Directory of Open Access Journals (Sweden)

Sophia Chui-Wai Ha

2015-10-01

Full Text Available Ankle inversion ligamentous sprain is one of the most common sports injuries. The most direct way is to investigate real injury incidents, but it is unethical and impossible to replicate on test participants. Simulators including tilt platforms, trapdoors, and fulcrum devices were designed to mimic ankle inversion movements in laboratories. Inversion angle was the only element considered in early designs; however, an ankle sprain is composed of inversion and plantarflexion in clinical observations. Inversion velocity is another parameter that increased the reality of simulation. This review summarised the simulators, and aimed to compare and contrast their features and settings.

Inverse optimization of objective function weights for treatment planning using clinical dose-volume histograms

Science.gov (United States)

Babier, Aaron; Boutilier, Justin J.; Sharpe, Michael B.; McNiven, Andrea L.; Chan, Timothy C. Y.

2018-05-01

We developed and evaluated a novel inverse optimization (IO) model to estimate objective function weights from clinical dose-volume histograms (DVHs). These weights were used to solve a treatment planning problem to generate ‘inverse plans’ that had similar DVHs to the original clinical DVHs. Our methodology was applied to 217 clinical head and neck cancer treatment plans that were previously delivered at Princess Margaret Cancer Centre in Canada. Inverse plan DVHs were compared to the clinical DVHs using objective function values, dose-volume differences, and frequency of clinical planning criteria satisfaction. Median differences between the clinical and inverse DVHs were within 1.1 Gy. For most structures, the difference in clinical planning criteria satisfaction between the clinical and inverse plans was at most 1.4%. For structures where the two plans differed by more than 1.4% in planning criteria satisfaction, the difference in average criterion violation was less than 0.5 Gy. Overall, the inverse plans were very similar to the clinical plans. Compared with a previous inverse optimization method from the literature, our new inverse plans typically satisfied the same or more clinical criteria, and had consistently lower fluence heterogeneity. Overall, this paper demonstrates that DVHs, which are essentially summary statistics, provide sufficient information to estimate objective function weights that result in high quality treatment plans. However, as with any summary statistic that compresses three-dimensional dose information, care must be taken to avoid generating plans with undesirable features such as hotspots; our computational results suggest that such undesirable spatial features were uncommon. Our IO-based approach can be integrated into the current clinical planning paradigm to better initialize the planning process and improve planning efficiency. It could also be embedded in a knowledge-based planning or adaptive radiation therapy framework to

Inverse planning anatomy-based dose optimization for HDR-brachytherapy of the prostate using fast simulated annealing algorithm and dedicated objective function

International Nuclear Information System (INIS)

Lessard, Etienne; Pouliot, Jean

2001-01-01

An anatomy-based dose optimization algorithm is developed to automatically and rapidly produce a highly conformal dose coverage of the target volume while minimizing urethra, bladder, and rectal doses in the delivery of an high dose-rate (HDR) brachytherapy boost for the treatment of prostate cancer. The dwell times are optimized using an inverse planning simulated annealing algorithm (IPSA) governed entirely from the anatomy extracted from a CT and by a dedicated objective function (cost function) reflecting clinical prescription and constraints. With this inverse planning approach, the focus is on the physician's prescription and constraint instead of on the technical limitations. Consequently, the physician's control on the treatment is improved. The capacity of this algorithm to represent the physician's prescription is presented for a clinical prostate case. The computation time (CPU) for IPSA optimization is less than 1 min (41 s for 142 915 iterations) for a typical clinical case, allowing fast and practical dose optimization. The achievement of highly conformal dose coverage to the target volume opens the possibility to deliver a higher dose to the prostate without inducing overdosage of urethra and normal tissues surrounding the prostate. Moreover, using the same concept, it will be possible to deliver a boost dose to a delimited tumor volume within the prostate. Finally, this method can be easily extended to other anatomical sites

Action understanding as inverse planning.

Science.gov (United States)

Baker, Chris L; Saxe, Rebecca; Tenenbaum, Joshua B

2009-12-01

Humans are adept at inferring the mental states underlying other agents' actions, such as goals, beliefs, desires, emotions and other thoughts. We propose a computational framework based on Bayesian inverse planning for modeling human action understanding. The framework represents an intuitive theory of intentional agents' behavior based on the principle of rationality: the expectation that agents will plan approximately rationally to achieve their goals, given their beliefs about the world. The mental states that caused an agent's behavior are inferred by inverting this model of rational planning using Bayesian inference, integrating the likelihood of the observed actions with the prior over mental states. This approach formalizes in precise probabilistic terms the essence of previous qualitative approaches to action understanding based on an "intentional stance" [Dennett, D. C. (1987). The intentional stance. Cambridge, MA: MIT Press] or a "teleological stance" [Gergely, G., Nádasdy, Z., Csibra, G., & Biró, S. (1995). Taking the intentional stance at 12 months of age. Cognition, 56, 165-193]. In three psychophysical experiments using animated stimuli of agents moving in simple mazes, we assess how well different inverse planning models based on different goal priors can predict human goal inferences. The results provide quantitative evidence for an approximately rational inference mechanism in human goal inference within our simplified stimulus paradigm, and for the flexible nature of goal representations that human observers can adopt. We discuss the implications of our experimental results for human action understanding in real-world contexts, and suggest how our framework might be extended to capture other kinds of mental state inferences, such as inferences about beliefs, or inferring whether an entity is an intentional agent.

Comparison of forward planning with automated inverse planning for three-dimensional conformal radiotherapy of non-small cell lung cancer without IMRT

International Nuclear Information System (INIS)

Mendes, Ruheena; Lavrenkov, Konstantin; Bedford, James L.; Henrys, Anthony; Ashley, Sue; Brada, Michael

2006-01-01

The forward and inverse treatment plans of 10 patients with lung cancer were compared in terms of PTV coverage, sparing of normal lung and time required to generate a plan. The inverse planning produced as good treatment plans as an experienced dosimetrist with considerable reduction in staff time. When translated to other complex sites, inverse non-IMRT planning may have considerable impact on manpower requirements

Effect of objective function on multi-objective inverse planning of radiation therapy

International Nuclear Information System (INIS)

Li Guoli; Wu Yican; Song Gang; Wang Shifang

2006-01-01

There are two kinds of objective functions in radiotherapy inverse planning: dose distribution-based and Dose-Volume Histogram (DVH)-based functions. The treatment planning in our days is still a trial and error process because the multi-objective problem is solved by transforming it into a single objective problem using a specific set of weights for each object. This work investigates the problem of objective function setting based on Pareto multi-optimization theory, and compares the effect on multi-objective inverse planning of those two kinds of objective functions including calculation time, converge speed, etc. The basis of objective function setting on inverse planning is discussed. (authors)

Inverse planning and optimization: a comparison of solutions

Energy Technology Data Exchange (ETDEWEB)

Ringor, Michael [School of Health Sciences, Purdue University, West Lafayette, IN (United States); Papiez, Lech [Department of Radiation Oncology, Indiana University, Indianapolis, IN (United States)

1998-09-01

The basic problem in radiation therapy treatment planning is to determine an appropriate set of treatment parameters that would induce an effective dose distribution inside a patient. One can approach this task as an inverse problem, or as an optimization problem. In this presentation, we compare both approaches. The inverse problem is presented as a dose reconstruction problem similar to tomography reconstruction. We formulate the optimization problem as linear and quadratic programs. Explicit comparisons are made between the solutions obtained by inversion and those obtained by optimization for the case in which scatter and attenuation are ignored (the NS-NA approximation)

Multi-objective optimization of inverse planning for accurate radiotherapy

International Nuclear Information System (INIS)

Cao Ruifen; Pei Xi; Cheng Mengyun; Li Gui; Hu Liqin; Wu Yican; Jing Jia; Li Guoli

2011-01-01

The multi-objective optimization of inverse planning based on the Pareto solution set, according to the multi-objective character of inverse planning in accurate radiotherapy, was studied in this paper. Firstly, the clinical requirements of a treatment plan were transformed into a multi-objective optimization problem with multiple constraints. Then, the fast and elitist multi-objective Non-dominated Sorting Genetic Algorithm (NSGA-II) was introduced to optimize the problem. A clinical example was tested using this method. The results show that an obtained set of non-dominated solutions were uniformly distributed and the corresponding dose distribution of each solution not only approached the expected dose distribution, but also met the dose-volume constraints. It was indicated that the clinical requirements were better satisfied using the method and the planner could select the optimal treatment plan from the non-dominated solution set. (authors)

Optimization of importance factors in inverse planning

International Nuclear Information System (INIS)

Xing, L.

1999-01-01

Inverse treatment planning starts with a treatment objective and obtains the solution by optimizing an objective function. The clinical objectives are usually multifaceted and potentially incompatible with one another. A set of importance factors is often incorporated in the objective function to parametrize trade-off strategies and to prioritize the dose conformality in different anatomical structures. Whereas the general formalism remains the same, different sets of importance factors characterize plans of obviously different flavour and thus critically determine the final plan. Up to now, the determination of these parameters has been a 'guessing' game based on empirical knowledge because the final dose distribution depends on the parameters in a complex and implicit way. The influence of these parameters is not known until the plan optimization is completed. In order to compromise properly the conflicting requirements of the target and sensitive structures, the parameters are usually adjusted through a trial-and-error process. In this paper, a method to estimate these parameters computationally is proposed and an iterative computer algorithm is described to determine these parameters numerically. The treatment plan selection is done in two steps. First, a set of importance factors are chosen and the corresponding beam parameters (e.g. beam profiles) are optimized under the guidance of a quadratic objective function using an iterative algorithm reported earlier. The 'optimal' plan is then evaluated by an additional scoring function. The importance factors in the objective function are accordingly adjusted to improve the ranking of the plan. For every change in the importance factors, the beam parameters need to be re-optimized. This process continues in an iterative fashion until the scoring function is saturated. The algorithm was applied to two clinical cases and the results demonstrated that it has the potential to improve significantly the existing method of

Inverse planning for x-ray rotation therapy: a general solution of the inverse problem

International Nuclear Information System (INIS)

Oelfke, U.; Bortfeld, T.

1999-01-01

Rotation therapy with photons is currently under investigation for the delivery of intensity modulated radiotherapy (IMRT). An analytical approach for inverse treatment planning of this radiotherapy technique is described. The inverse problem for the delivery of arbitrary 2D dose profiles is first formulated and then solved analytically. In contrast to previously applied strategies for solving the inverse problem, it is shown that the most general solution for the fluence profiles consists of two independent solutions of different parity. A first analytical expression for both fluence profiles is derived. The mathematical derivation includes two different strategies, an elementary expansion of fluence and dose into polynomials and a more practical approach in terms of Fourier transforms. The obtained results are discussed in the context of previous work on this problem. (author)

Implementation of a Monte Carlo based inverse planning model for clinical IMRT with MCNP code

International Nuclear Information System (INIS)

He, Tongming Tony

2003-01-01

Inaccurate dose calculations and limitations of optimization algorithms in inverse planning introduce systematic and convergence errors to treatment plans. This work was to implement a Monte Carlo based inverse planning model for clinical IMRT aiming to minimize the aforementioned errors. The strategy was to precalculate the dose matrices of beamlets in a Monte Carlo based method followed by the optimization of beamlet intensities. The MCNP 4B (Monte Carlo N-Particle version 4B) code was modified to implement selective particle transport and dose tallying in voxels and efficient estimation of statistical uncertainties. The resulting performance gain was over eleven thousand times. Due to concurrent calculation of multiple beamlets of individual ports, hundreds of beamlets in an IMRT plan could be calculated within a practical length of time. A finite-sized point source model provided a simple and accurate modeling of treatment beams. The dose matrix calculations were validated through measurements in phantoms. Agreements were better than 1.5% or 0.2 cm. The beamlet intensities were optimized using a parallel platform based optimization algorithm that was capable of escape from local minima and preventing premature convergence. The Monte Carlo based inverse planning model was applied to clinical cases. The feasibility and capability of Monte Carlo based inverse planning for clinical IMRT was demonstrated. Systematic errors in treatment plans of a commercial inverse planning system were assessed in comparison with the Monte Carlo based calculations. Discrepancies in tumor doses and critical structure doses were up to 12% and 17%, respectively. The clinical importance of Monte Carlo based inverse planning for IMRT was demonstrated

Prostate Dose Escalation by a Innovative Inverse Planning-Driven IMRT

National Research Council Canada - National Science Library

Xing, Lei

2008-01-01

...) Developed a voxel-specific penalty scheme for TRV-based inverse planning; (iv) Established a cine-EPID image retrospective dose reconstruction in IMRT dose delivery for adaptive planning and IMRT dose verification. These works are both timely and important and should lead to widespread impact on prostate cancer management.

Inversion based on computational simulations

International Nuclear Information System (INIS)

Hanson, K.M.; Cunningham, G.S.; Saquib, S.S.

1998-01-01

A standard approach to solving inversion problems that involve many parameters uses gradient-based optimization to find the parameters that best match the data. The authors discuss enabling techniques that facilitate application of this approach to large-scale computational simulations, which are the only way to investigate many complex physical phenomena. Such simulations may not seem to lend themselves to calculation of the gradient with respect to numerous parameters. However, adjoint differentiation allows one to efficiently compute the gradient of an objective function with respect to all the variables of a simulation. When combined with advanced gradient-based optimization algorithms, adjoint differentiation permits one to solve very large problems of optimization or parameter estimation. These techniques will be illustrated through the simulation of the time-dependent diffusion of infrared light through tissue, which has been used to perform optical tomography. The techniques discussed have a wide range of applicability to modeling including the optimization of models to achieve a desired design goal

A general method for closed-loop inverse simulation of helicopter maneuver flight

Directory of Open Access Journals (Sweden)

Wei WU

2017-12-01

Full Text Available Maneuverability is a key factor to determine whether a helicopter could finish certain flight missions successfully or not. Inverse simulation is commonly used to calculate the pilot controls of a helicopter to complete a certain kind of maneuver flight and to assess its maneuverability. A general method for inverse simulation of maneuver flight for helicopters with the flight control system online is developed in this paper. A general mathematical describing function is established to provide mathematical descriptions of different kinds of maneuvers. A comprehensive control solver based on the optimal linear quadratic regulator theory is developed to calculate the pilot controls of different maneuvers. The coupling problem between pilot controls and flight control system outputs is well solved by taking the flight control system model into the control solver. Inverse simulation of three different kinds of maneuvers with different agility requirements defined in the ADS-33E-PRF is implemented based on the developed method for a UH-60 helicopter. The results show that the method developed in this paper can solve the closed-loop inverse simulation problem of helicopter maneuver flight with high reliability as well as efficiency. Keywords: Closed-loop, Flying quality, Helicopters, Inverse simulation, Maneuver flight

Inverse simulation system for evaluating handling qualities during rendezvous and docking

Science.gov (United States)

Zhou, Wanmeng; Wang, Hua; Thomson, Douglas; Tang, Guojin; Zhang, Fan

2017-08-01

The traditional method used for handling qualities assessment of manned space vehicles is too time-consuming to meet the requirements of an increasingly fast design process. In this study, a rendezvous and docking inverse simulation system to assess the handling qualities of spacecraft is proposed using a previously developed model-predictive-control architecture. By considering the fixed discrete force of the thrusters of the system, the inverse model is constructed using the least squares estimation method with a hyper-ellipsoidal restriction, the continuous control outputs of which are subsequently dispersed by pulse width modulation with sensitivity factors introduced. The inputs in every step are deemed constant parameters, and the method could be considered as a general method for solving nominal, redundant, and insufficient inverse problems. The rendezvous and docking inverse simulation is applied to a nine-degrees-of-freedom platform, and a novel handling qualities evaluation scheme is established according to the operation precision and astronauts' workload. Finally, different nominal trajectories are scored by the inverse simulation and an established evaluation scheme. The scores can offer theoretical guidance for astronaut training and more complex operation missions.

Poster - 33: Dosimetry Comparison of Prone Breast Forward and Inverse Treatment planning considering daily setup variations

Energy Technology Data Exchange (ETDEWEB)

Jiang, Runqing; Zhan, Lixin; Osei, Ernest [Grand River Regional Cancer Centre (Canada)

2016-08-15

Introduction: The purpose of this study is to investigate the effects of daily setup variations on prone breast forward field-in-field (FinF) and inverse IMRT treatment planning. Methods: Rando Phantom (Left breast) and Pixy phantom (Right breast) were built and CT scanned in prone position. The treatment planning (TP) is performed in Eclipse TP system. Forward FinF plan and inverse IMRT plan were created to satisfy the CTV coverage and OARs criteria. The daily setup variations were assumed to be 5 mm at left-right, superior-inferior, and anterior-posterior directions. The DVHs of CTV coverage and OARs were compared for both forward FinF plan and inverse IMRT plans due to 5mm setup variation. Results and Discussions: DVHs of CTV coverage had fewer variations for 5m setup variation for forward FinF and inverse IMRT plan for both phantoms. However, for the setup variations in the left-right direction, the DVH of CTV coverage of IMRT plan showed the worst variation due to lateral setup variation for both phantoms. For anterior-posterior variation, the CTV could not get full coverage when the breast chest wall is shallow; however, with the guidance of MV imaging, breast chest wall will be checked during the MV imaging setup. So the setup variations have more effects on inverse IMRT plan, compared to forward FinF plan, especially in the left-right direction. Conclusions: The Forward FinF plan was recommended clinically considering daily setup variation.

A Simulation Tool for the Study of Symmetric Inversions in Bacterial Genomes

Science.gov (United States)

Dias, Ulisses; Dias, Zanoni; Setubal, João C.

We present the tool SIB that simulates genomic inversions in bacterial chromosomes. The tool simulates symmetric inversions but allows the appearance of nonsymmetric inversions by simulating small syntenic blocks frequently observed on bacterial genome comparisons. We evaluate SIB by comparing its results to real genome alignments. We develop measures that allow quantitative comparisons between real pairwise alignments (in terms of dotplots) and simulated ones. These measures allow an evaluation of SIB in terms of dendrograms. We evaluate SIB by comparing its results to whole chromosome alignments and maximum likelihood trees for three bacterial groups (the Pseudomonadaceae family and the Xanthomonas and Shewanella genera). We demonstrate an application of SIB by using it to evaluate the ancestral genome reconstruction tool MGR.

A gEUD-based inverse planning technique for HDR prostate brachytherapy: Feasibility study

Energy Technology Data Exchange (ETDEWEB)

Giantsoudi, D. [Department of Radiological Sciences, University of Texas Health Sciences Center, San Antonio, Texas 78229 (United States); Department of Radiation Oncology, Francis H. Burr Proton Therapy Center, Boston, Massachusetts 02114 (United States); Baltas, D. [Department of Medical Physics and Engineering, Strahlenklinik, Klinikum Offenbach GmbH, 63069 Offenbach (Germany); Nuclear and Particle Physics Section, Physics Department, University of Athens, 15701 Athens (Greece); Karabis, A. [Pi-Medical Ltd., Athens 10676 (Greece); Mavroidis, P. [Department of Radiological Sciences, University of Texas Health Sciences Center, San Antonio, Texas 78299 and Department of Medical Radiation Physics, Karolinska Institutet and Stockholm University, 17176 (Sweden); Zamboglou, N.; Tselis, N. [Strahlenklinik, Klinikum Offenbach GmbH, 63069 Offenbach (Germany); Shi, C. [St. Vincent' s Medical Center, 2800 Main Street, Bridgeport, Connecticut 06606 (United States); Papanikolaou, N. [Department of Radiological Sciences, University of Texas Health Sciences Center, San Antonio, Texas 78299 (United States)

2013-04-15

Purpose: The purpose of this work was to study the feasibility of a new inverse planning technique based on the generalized equivalent uniform dose for image-guided high dose rate (HDR) prostate cancer brachytherapy in comparison to conventional dose-volume based optimization. Methods: The quality of 12 clinical HDR brachytherapy implants for prostate utilizing HIPO (Hybrid Inverse Planning Optimization) is compared with alternative plans, which were produced through inverse planning using the generalized equivalent uniform dose (gEUD). All the common dose-volume indices for the prostate and the organs at risk were considered together with radiobiological measures. The clinical effectiveness of the different dose distributions was investigated by comparing dose volume histogram and gEUD evaluators. Results: Our results demonstrate the feasibility of gEUD-based inverse planning in HDR brachytherapy implants for prostate. A statistically significant decrease in D{sub 10} or/and final gEUD values for the organs at risk (urethra, bladder, and rectum) was found while improving dose homogeneity or dose conformity of the target volume. Conclusions: Following the promising results of gEUD-based optimization in intensity modulated radiation therapy treatment optimization, as reported in the literature, the implementation of a similar model in HDR brachytherapy treatment plan optimization is suggested by this study. The potential of improved sparing of organs at risk was shown for various gEUD-based optimization parameter protocols, which indicates the ability of this method to adapt to the user's preferences.

Evaluation of an artificial intelligence guided inverse planning system: Clinical case study

International Nuclear Information System (INIS)

Yan Hui; Yin Fangfang; Willett, Christopher

2007-01-01

Purpose: An artificial intelligence (AI) guided method for parameter adjustment of inverse planning was implemented on a commercial inverse treatment planning system. For evaluation purpose, four typical clinical cases were tested and the results from both plans achieved by automated and manual methods were compared. Methods and materials: The procedure of parameter adjustment mainly consists of three major loops. Each loop is in charge of modifying parameters of one category, which is carried out by a specially customized fuzzy inference system. A physician prescribed multiple constraints for a selected volume were adopted to account for the tradeoff between prescription dose to the PTV and dose-volume constraints for critical organs. The searching process for an optimal parameter combination began with the first constraint, and proceeds to the next until a plan with acceptable dose was achieved. The initial setup of the plan parameters was the same for each case and was adjusted independently by both manual and automated methods. After the parameters of one category were updated, the intensity maps of all fields were re-optimized and the plan dose was subsequently re-calculated. When final plan arrived, the dose statistics were calculated from both plans and compared. Results: For planned target volume (PTV), the dose for 95% volume is up to 10% higher in plans using the automated method than those using the manual method. For critical organs, an average decrease of the plan dose was achieved. However, the automated method cannot improve the plan dose for some critical organs due to limitations of the inference rules currently employed. For normal tissue, there was no significant difference between plan doses achieved by either automated or manual method. Conclusion: With the application of AI-guided method, the basic parameter adjustment task can be accomplished automatically and a comparable plan dose was achieved in comparison with that achieved by the manual

Evaluation of an artificial intelligence guided inverse planning system: clinical case study.

Science.gov (United States)

Yan, Hui; Yin, Fang-Fang; Willett, Christopher

2007-04-01

An artificial intelligence (AI) guided method for parameter adjustment of inverse planning was implemented on a commercial inverse treatment planning system. For evaluation purpose, four typical clinical cases were tested and the results from both plans achieved by automated and manual methods were compared. The procedure of parameter adjustment mainly consists of three major loops. Each loop is in charge of modifying parameters of one category, which is carried out by a specially customized fuzzy inference system. A physician prescribed multiple constraints for a selected volume were adopted to account for the tradeoff between prescription dose to the PTV and dose-volume constraints for critical organs. The searching process for an optimal parameter combination began with the first constraint, and proceeds to the next until a plan with acceptable dose was achieved. The initial setup of the plan parameters was the same for each case and was adjusted independently by both manual and automated methods. After the parameters of one category were updated, the intensity maps of all fields were re-optimized and the plan dose was subsequently re-calculated. When final plan arrived, the dose statistics were calculated from both plans and compared. For planned target volume (PTV), the dose for 95% volume is up to 10% higher in plans using the automated method than those using the manual method. For critical organs, an average decrease of the plan dose was achieved. However, the automated method cannot improve the plan dose for some critical organs due to limitations of the inference rules currently employed. For normal tissue, there was no significant difference between plan doses achieved by either automated or manual method. With the application of AI-guided method, the basic parameter adjustment task can be accomplished automatically and a comparable plan dose was achieved in comparison with that achieved by the manual method. Future improvements to incorporate case

When does treatment plan optimization require inverse planning?

International Nuclear Information System (INIS)

Sherouse, George W.

1995-01-01

which the most sophisticated techniques of inverse planning represent a cost-effective solution is relatively small, and that surprisingly simple optimization techniques (and correspondingly simple treatment delivery techniques) can reliably produce acceptable results for the majority of routine conformal radiotherapy practice

The influence of air temperature inversions on snowmelt and glacier mass-balance simulations, Ammassalik island, SE Greenland

Energy Technology Data Exchange (ETDEWEB)

Mernild, Sebastian Haugard [Los Alamos National Laboratory; Liston, Glen [COLORADO STATE UNIV.

2009-01-01

In many applications, a realistic description of air temperature inversions is essential for accurate snow and glacier ice melt, and glacier mass-balance simulations. A physically based snow-evolution modeling system (SnowModel) was used to simulate eight years (1998/99 to 2005/06) of snow accumulation and snow and glacier ice ablation from numerous small coastal marginal glaciers on the SW-part of Ammassalik Island in SE Greenland. These glaciers are regularly influenced by inversions and sea breezes associated with the adjacent relatively low temperature and frequently ice-choked fjords and ocean. To account for the influence of these inversions on the spatiotemporal variation of air temperature and snow and glacier melt rates, temperature inversion routines were added to MircoMet, the meteorological distribution sub-model used in SnowModel. The inversions were observed and modeled to occur during 84% of the simulation period. Modeled inversions were defined not to occur during days with strong winds and high precipitation rates due to the potential of inversion break-up. Field observations showed inversions to extend from sea level to approximately 300 m a.s.l., and this inversion level was prescribed in the model simulations. Simulations with and without the inversion routines were compared. The inversion model produced air temperature distributions with warmer lower elevation areas and cooler higher elevation areas than without inversion routines due to the use of cold sea-breeze base temperature data from underneath the inversion. This yielded an up to 2 weeks earlier snowmelt in the lower areas and up to 1 to 3 weeks later snowmelt in the higher elevation areas of the simulation domain. Averaged mean annual modeled surface mass-balance for all glaciers (mainly located above the inversion layer) was -720 {+-} 620 mm w.eq. y{sup -1} for inversion simulations, and -880 {+-} 620 mm w.eq. y{sup -1} without the inversion routines, a difference of 160 mm w.eq. y

MATLAB Simulation of Gradient-Based Neural Network for Online Matrix Inversion

Science.gov (United States)

Zhang, Yunong; Chen, Ke; Ma, Weimu; Li, Xiao-Dong

This paper investigates the simulation of a gradient-based recurrent neural network for online solution of the matrix-inverse problem. Several important techniques are employed as follows to simulate such a neural system. 1) Kronecker product of matrices is introduced to transform a matrix-differential-equation (MDE) to a vector-differential-equation (VDE); i.e., finally, a standard ordinary-differential-equation (ODE) is obtained. 2) MATLAB routine "ode45" is introduced to solve the transformed initial-value ODE problem. 3) In addition to various implementation errors, different kinds of activation functions are simulated to show the characteristics of such a neural network. Simulation results substantiate the theoretical analysis and efficacy of the gradient-based neural network for online constant matrix inversion.

An efficient inverse radiotherapy planning method for VMAT using quadratic programming optimization.

Science.gov (United States)

Hoegele, W; Loeschel, R; Merkle, N; Zygmanski, P

2012-01-01

The purpose of this study is to investigate the feasibility of an inverse planning optimization approach for the Volumetric Modulated Arc Therapy (VMAT) based on quadratic programming and the projection method. The performance of this method is evaluated against a reference commercial planning system (eclipse(TM) for rapidarc(TM)) for clinically relevant cases. The inverse problem is posed in terms of a linear combination of basis functions representing arclet dose contributions and their respective linear coefficients as degrees of freedom. MLC motion is decomposed into basic motion patterns in an intuitive manner leading to a system of equations with a relatively small number of equations and unknowns. These equations are solved using quadratic programming under certain limiting physical conditions for the solution, such as the avoidance of negative dose during optimization and Monitor Unit reduction. The modeling by the projection method assures a unique treatment plan with beneficial properties, such as the explicit relation between organ weightings and the final dose distribution. Clinical cases studied include prostate and spine treatments. The optimized plans are evaluated by comparing isodose lines, DVH profiles for target and normal organs, and Monitor Units to those obtained by the clinical treatment planning system eclipse(TM). The resulting dose distributions for a prostate (with rectum and bladder as organs at risk), and for a spine case (with kidneys, liver, lung and heart as organs at risk) are presented. Overall, the results indicate that similar plan qualities for quadratic programming (QP) and rapidarc(TM) could be achieved at significantly more efficient computational and planning effort using QP. Additionally, results for the quasimodo phantom [Bohsung et al., "IMRT treatment planning: A comparative inter-system and inter-centre planning exercise of the estro quasimodo group," Radiother. Oncol. 76(3), 354-361 (2005)] are presented as an example

Expected treatment dose construction and adaptive inverse planning optimization: Implementation for offline head and neck cancer adaptive radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Yan Di; Liang Jian [Department of Radiation Oncology, Beaumont Health System, Royal Oak, Michigan 48073 (United States)

2013-02-15

Purpose: To construct expected treatment dose for adaptive inverse planning optimization, and evaluate it on head and neck (h and n) cancer adaptive treatment modification. Methods: Adaptive inverse planning engine was developed and integrated in our in-house adaptive treatment control system. The adaptive inverse planning engine includes an expected treatment dose constructed using the daily cone beam (CB) CT images in its objective and constrains. Feasibility of the adaptive inverse planning optimization was evaluated retrospectively using daily CBCT images obtained from the image guided IMRT treatment of 19 h and n cancer patients. Adaptive treatment modification strategies with respect to the time and the number of adaptive inverse planning optimization during the treatment course were evaluated using the cumulative treatment dose in organs of interest constructed using all daily CBCT images. Results: Expected treatment dose was constructed to include both the delivered dose, to date, and the estimated dose for the remaining treatment during the adaptive treatment course. It was used in treatment evaluation, as well as in constructing the objective and constraints for adaptive inverse planning optimization. The optimization engine is feasible to perform planning optimization based on preassigned treatment modification schedule. Compared to the conventional IMRT, the adaptive treatment for h and n cancer illustrated clear dose-volume improvement for all critical normal organs. The dose-volume reductions of right and left parotid glands, spine cord, brain stem and mandible were (17 {+-} 6)%, (14 {+-} 6)%, (11 {+-} 6)%, (12 {+-} 8)%, and (5 {+-} 3)% respectively with the single adaptive modification performed after the second treatment week; (24 {+-} 6)%, (22 {+-} 8)%, (21 {+-} 5)%, (19 {+-} 8)%, and (10 {+-} 6)% with three weekly modifications; and (28 {+-} 5)%, (25 {+-} 9)%, (26 {+-} 5)%, (24 {+-} 8)%, and (15 {+-} 9)% with five weekly modifications. Conclusions

A general method for closed-loop inverse simulation of helicopter maneuver flight

OpenAIRE

Wei WU

2017-01-01

Maneuverability is a key factor to determine whether a helicopter could finish certain flight missions successfully or not. Inverse simulation is commonly used to calculate the pilot controls of a helicopter to complete a certain kind of maneuver flight and to assess its maneuverability. A general method for inverse simulation of maneuver flight for helicopters with the flight control system online is developed in this paper. A general mathematical describing function is established to provid...

Pre-clinical evaluation of an inverse planning module for segmental MLC based IMRT delivery

International Nuclear Information System (INIS)

Georg, Dietmar; Kroupa, Bernhard

2002-01-01

Phantom tests are performed for pre-clinical evaluation of a commercial inverse planning system (HELAX TMS, V 6.0) for segmented multileaf collimator (MLC) intensity modulated radiotherapy (IMRT) delivery. The optimization module has available two optimization algorithms: the target primary feasibility and the weighted feasibility algorithm, only the latter allows the user to specify weights for structures. In the first series, single beam tests are performed to evaluate the outcome of inverse planning in terms of plausibility for the following situations: oblique incidence, presence of inhomogeneities, multiple targets at different depths and multiple targets with different desired doses. Additionally, for these tests a manual plan is made for comparison. In the absence of organs at risk, both the optimization algorithms are found to assign the highest priority to low dose constraints for targets. In the second series, tests resembling clinical relevant configurations (simultaneous boost and concave target with critical organ) are performed with multiple beam arrangements in order to determine the impact of the system's configuration on inverse planning. It is found that the definition of certain segment number and segment size limitations does not largely compromise treatment plans when using multiple beams. On the other hand, these limitations are important for delivery efficiency and dosimetry. For the number of iterations and voxels per volume of interest, standard values in the system's configuration are considered to be sufficient. Additionally, it is demonstrated that precautions must be taken to precisely define treatment goals when using computerized treatment optimization. Similar phantom tests could be used for a direct dosimetric verification of all steps from inverse treatment planning to IMRT delivery. (note)

The Trump tax plan halts inversions but increases treaty shopping

NARCIS (Netherlands)

Lejour, Arjen; Cnossen, Sybren; van 't Riet, Maarten

2017-01-01

Some US multinationals have displayed a willingness to relinquish their American nationality and move their headquarters abroad. Such ‘inversions’ generally aim to avoid and minimise taxes. This column argues that the new Trump tax plan is likely to halt tax inversions by US multinationals. However,

From analytic inversion to contemporary IMRT optimization: radiation therapy planning revisited from a mathematical perspective.

Science.gov (United States)

Censor, Yair; Unkelbach, Jan

2012-04-01

In this paper we look at the development of radiation therapy treatment planning from a mathematical point of view. Historically, planning for Intensity-Modulated Radiation Therapy (IMRT) has been considered as an inverse problem. We discuss first the two fundamental approaches that have been investigated to solve this inverse problem: Continuous analytic inversion techniques on one hand, and fully-discretized algebraic methods on the other hand. In the second part of the paper, we review another fundamental question which has been subject to debate from the beginning of IMRT until the present day: The rotation therapy approach versus fixed angle IMRT. This builds a bridge from historic work on IMRT planning to contemporary research in the context of Intensity-Modulated Arc Therapy (IMAT). Copyright © 2011 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

The use of mixed-integer programming for inverse treatment planning with pre-defined field segments

International Nuclear Information System (INIS)

Bednarz, Greg; Michalski, Darek; Houser, Chris; Huq, M. Saiful; Xiao Ying; Rani, Pramila Anne; Galvin, James M.

2002-01-01

Complex intensity patterns generated by traditional beamlet-based inverse treatment plans are often very difficult to deliver. In the approach presented in this work the intensity maps are controlled by pre-defining field segments to be used for dose optimization. A set of simple rules was used to define a pool of allowable delivery segments and the mixed-integer programming (MIP) method was used to optimize segment weights. The optimization problem was formulated by combining real variables describing segment weights with a set of binary variables, used to enumerate voxels in targets and critical structures. The MIP method was compared to the previously used Cimmino projection algorithm. The field segmentation approach was compared to an inverse planning system with a traditional beamlet-based beam intensity optimization. In four complex cases of oropharyngeal cancer the segmental inverse planning produced treatment plans, which competed with traditional beamlet-based IMRT plans. The mixed-integer programming provided mechanism for imposition of dose-volume constraints and allowed for identification of the optimal solution for feasible problems. Additional advantages of the segmental technique presented here are: simplified dosimetry, quality assurance and treatment delivery. (author)

Treatment planning for multicatheter interstitial brachytherapy of breast cancer – from Paris system to anatomy-based inverse planning

Directory of Open Access Journals (Sweden)

Tibor Major

2017-02-01

Full Text Available In the last decades, treatment planning for multicatheter interstitial breast brachytherapy has evolved considerably from fluoroscopy-based 2D to anatomy-based 3D planning. To plan the right positions of the catheters, ultrasound or computed tomography (CT imaging can be used, but the treatment plan is always based on postimplant CT images. With CT imaging, the 3D target volume can be defined more precisely and delineation of the organs at risk volumes is also possible. Consequently, parameters calculated from dose-volume histogram can be used for quantitative plan evaluation. The catheter reconstruction is also easier and faster on CT images compared to X-ray films. In high dose rate brachytherapy, using a stepping source, a number of forward dose optimization methods (manual, geometrical, on dose points, graphical are available to shape the dose distribution to the target volume, and these influence dose homogeneities to different extent. Currently, inverse optimization algorithms offer new possibilities to improve dose distributions further considering the requirements for dose coverage, dose homogeneity, and dose to organs at risk simultaneously and automatically. In this article, the evolvement of treatment planning for interstitial breast implants is reviewed, different forward optimization methods are discussed, and dose-volume parameters used for quantitative plan evaluation are described. Finally, some questions of the inverse optimization method are investigated and initial experiences of the authors are presented.

Comparison of three IMRT inverse planning techniques that allow for partial esophagus sparing in patients receiving thoracic radiation therapy for lung cancer

International Nuclear Information System (INIS)

Xiao Ying; Werner-Wasik, Maria; Michalski, D.; Houser, C.; Bednarz, G.; Curran, W.; Galvin, James

2004-01-01

The purpose of this study is to compare 3 intensity-modulated radiation therapy (IMRT) inverse treatment planning techniques as applied to locally-advanced lung cancer. This study evaluates whether sufficient radiotherapy (RT) dose is given for durable control of tumors while sparing a portion of the esophagus, and whether large number of segments and monitor units are required. We selected 5 cases of locally-advanced lung cancer with large central tumor, abutting the esophagus. To ensure that no more than half of the esophagus circumference at any level received the specified dose limit, it was divided into disk-like sections and dose limits were imposed on each. Two sets of dose objectives were specified for tumor and other critical structures for standard dose RT and for dose escalation RT. Plans were generated using an aperture-based inverse planning (ABIP) technique with the Cimmino algorithm for optimization. Beamlet-based inverse treatment planning was carried out with a commercial simulated annealing package (CORVUS) and with an in-house system that used the Cimmino projection algorithm (CIMM). For 3 of the 5 cases, results met all of the constraints from the 3 techniques for the 2 sets of dose objectives. The CORVUS system without delivery efficiency consideration required the most segments and monitor units. The CIMM system reduced the number while the ABIP techniques showed a further reduction, although for one of the cases, a solution was not readily obtained using the ABIP technique for dose escalation objectives

Robotic path-finding in inverse treatment planning for stereotactic radiosurgery with continuous dose delivery

Energy Technology Data Exchange (ETDEWEB)

Vandewouw, Marlee M., E-mail: marleev@mie.utoronto.ca; Aleman, Dionne M. [Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario M5S 3G8 (Canada); Jaffray, David A. [Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario M5G 2M9 (Canada)

2016-08-15

Purpose: Continuous dose delivery in radiation therapy treatments has been shown to decrease total treatment time while improving the dose conformity and distribution homogeneity over the conventional step-and-shoot approach. The authors develop an inverse treatment planning method for Gamma Knife® Perfexion™ that continuously delivers dose along a path in the target. Methods: The authors’ method is comprised of two steps: find a path within the target, then solve a mixed integer optimization model to find the optimal collimator configurations and durations along the selected path. Robotic path-finding techniques, specifically, simultaneous localization and mapping (SLAM) using an extended Kalman filter, are used to obtain a path that travels sufficiently close to selected isocentre locations. SLAM is novelly extended to explore a 3D, discrete environment, which is the target discretized into voxels. Further novel extensions are incorporated into the steering mechanism to account for target geometry. Results: The SLAM method was tested on seven clinical cases and compared to clinical, Hamiltonian path continuous delivery, and inverse step-and-shoot treatment plans. The SLAM approach improved dose metrics compared to the clinical plans and Hamiltonian path continuous delivery plans. Beam-on times improved over clinical plans, and had mixed performance compared to Hamiltonian path continuous plans. The SLAM method is also shown to be robust to path selection inaccuracies, isocentre selection, and dose distribution. Conclusions: The SLAM method for continuous delivery provides decreased total treatment time and increased treatment quality compared to both clinical and inverse step-and-shoot plans, and outperforms existing path methods in treatment quality. It also accounts for uncertainty in treatment planning by accommodating inaccuracies.

Robotic path-finding in inverse treatment planning for stereotactic radiosurgery with continuous dose delivery

International Nuclear Information System (INIS)

Vandewouw, Marlee M.; Aleman, Dionne M.; Jaffray, David A.

2016-01-01

Purpose: Continuous dose delivery in radiation therapy treatments has been shown to decrease total treatment time while improving the dose conformity and distribution homogeneity over the conventional step-and-shoot approach. The authors develop an inverse treatment planning method for Gamma Knife® Perfexion™ that continuously delivers dose along a path in the target. Methods: The authors’ method is comprised of two steps: find a path within the target, then solve a mixed integer optimization model to find the optimal collimator configurations and durations along the selected path. Robotic path-finding techniques, specifically, simultaneous localization and mapping (SLAM) using an extended Kalman filter, are used to obtain a path that travels sufficiently close to selected isocentre locations. SLAM is novelly extended to explore a 3D, discrete environment, which is the target discretized into voxels. Further novel extensions are incorporated into the steering mechanism to account for target geometry. Results: The SLAM method was tested on seven clinical cases and compared to clinical, Hamiltonian path continuous delivery, and inverse step-and-shoot treatment plans. The SLAM approach improved dose metrics compared to the clinical plans and Hamiltonian path continuous delivery plans. Beam-on times improved over clinical plans, and had mixed performance compared to Hamiltonian path continuous plans. The SLAM method is also shown to be robust to path selection inaccuracies, isocentre selection, and dose distribution. Conclusions: The SLAM method for continuous delivery provides decreased total treatment time and increased treatment quality compared to both clinical and inverse step-and-shoot plans, and outperforms existing path methods in treatment quality. It also accounts for uncertainty in treatment planning by accommodating inaccuracies.

A comparison of forward planning and optimised inverse planning

International Nuclear Information System (INIS)

Oldham, Mark; Neal, Anthony; Webb, Steve

1995-01-01

A radiotherapy treatment plan optimisation algorithm has been applied to 48 prostate plans and the results compared with those of an experienced human planner. Twelve patients were used in the study, and a 3, 4, 6 and 8 field plan (with standard coplanar beam angles for each plan type) were optimised by both the human planner and the optimisation algorithm. The human planner 'optimised' the plan by conventional forward planning techniques. The optimisation algorithm was based on fast-simulated-annealing. 'Importance factors' assigned to different regions of the patient provide a method for controlling the algorithm, and it was found that the same values gave good results for almost all plans. The plans were compared on the basis of dose statistics and normal-tissue-complication-probability (NTCP) and tumour-control-probability (TCP). The results show that the optimisation algorithm yielded results that were at least as good as the human planner for all plan types, and on the whole slightly better. A study of the beam-weights chosen by the optimisation algorithm and the planner will be presented. The optimisation algorithm showed greater variation, in response to individual patient geometry. For simple (e.g. 3 field) plans it was found to consistently achieve slightly higher TCP and lower NTCP values. For more complicated (e.g. 8 fields) plans the optimisation also achieved slightly better results with generally less numbers of beams. The optimisation time was always ≤5 minutes; a factor of up to 20 times faster than the human planner

Incorporating organ movements in IMRT treatment planning for prostate cancer: Minimizing uncertainties in the inverse planning process

International Nuclear Information System (INIS)

Unkelbach, Jan; Oelfke, Uwe

2005-01-01

We investigate an off-line strategy to incorporate inter fraction organ movements in IMRT treatment planning. Nowadays, imaging modalities located in the treatment room allow for several CT scans of a patient during the course of treatment. These multiple CT scans can be used to estimate a probability distribution of possible patient geometries. This probability distribution can subsequently be used to calculate the expectation value of the delivered dose distribution. In order to incorporate organ movements into the treatment planning process, it was suggested that inverse planning could be based on that probability distribution of patient geometries instead of a single snapshot. However, it was shown that a straightforward optimization of the expectation value of the dose may be insufficient since the expected dose distribution is related to several uncertainties: first, this probability distribution has to be estimated from only a few images. And second, the distribution is only sparsely sampled over the treatment course due to a finite number of fractions. In order to obtain a robust treatment plan these uncertainties should be considered and minimized in the inverse planning process. In the current paper, we calculate a 3D variance distribution in addition to the expectation value of the dose distribution which are simultaniously optimized. The variance is used as a surrogate to quantify the associated risks of a treatment plan. The feasibility of this approach is demonstrated for clinical data of prostate patients. Different scenarios of dose expectation values and corresponding variances are discussed

Incorporating organ movements in inverse planning: assessing dose uncertainties by Bayesian inference

International Nuclear Information System (INIS)

Unkelbach, J; Oelfke, U

2005-01-01

We present a method to calculate dose uncertainties due to inter-fraction organ movements in fractionated radiotherapy, i.e. in addition to the expectation value of the dose distribution a variance distribution is calculated. To calculate the expectation value of the dose distribution in the presence of organ movements, one estimates a probability distribution of possible patient geometries. The respective variance of the expected dose distribution arises for two reasons: first, the patient is irradiated with a finite number of fractions only and second, the probability distribution of patient geometries has to be estimated from a small number of images and is therefore not exactly known. To quantify the total dose variance, we propose a method that is based on the principle of Bayesian inference. The method is of particular interest when organ motion is incorporated in inverse IMRT planning by means of inverse planning performed on a probability distribution of patient geometries. In order to make this a robust approach, it turns out that the dose variance should be considered (and minimized) in the optimization process. As an application of the presented concept of Bayesian inference, we compare three approaches to inverse planning based on probability distributions that account for an increasing degree of uncertainty. The Bayes theorem further provides a concept to interpolate between patient specific data and population-based knowledge on organ motion which is relevant since the number of CT images of a patient is typically small

Using measurable dosimetric quantities to characterize the inter-structural tradeoff in inverse planning

Science.gov (United States)

Liu, Hongcheng; Dong, Peng; Xing, Lei

2017-08-01

Traditional inverse planning relies on the use of weighting factors to balance the conflicting requirements of different structures. Manual trial-and-error determination of weighting factors has long been recognized as a time-consuming part of treatment planning. The purpose of this work is to develop an inverse planning framework that parameterizes the dosimetric tradeoff among the structures with physically meaningful quantities to simplify the search for clinically sensible plans. In this formalism, instead of using weighting factors, the permissible variation range of the prescription dose or dose volume histogram (DVH) of the involved structures are used to characterize the ‘importance’ of the structures. The inverse planning is then formulated into a convex feasibility problem, called the dosimetric variation-controlled model (DVCM), whose goal is to generate plans with dosimetric or DVH variations of the structures consistent with the pre-specified values. For simplicity, the dosimetric variation range for a structure is extracted from a library of previous cases which possess similar anatomy and prescription. A two-phase procedure (TPP) is designed to solve the model. The first phase identifies a physically feasible plan to satisfy the prescribed dosimetric variation, and the second phase automatically improves the plan in case there is room for further improvement. The proposed technique is applied to plan two prostate cases and two head-and-neck cases and the results are compared with those obtained using a conventional CVaR approach and with a moment-based optimization scheme. Our results show that the strategy is able to generate clinically sensible plans with little trial and error. In all cases, the TPP generates a very competitive plan as compared to those obtained using the alternative approaches. Particularly, in the planning of one of the head-and-neck cases, the TPP leads to a non-trivial improvement in the resultant dose distribution�

From capture to simulation: connecting forward and inverse problems in fluids

KAUST Repository

Gregson, James; Ihrke, Ivo; Thuerey, Nils; Heidrich, Wolfgang

2014-01-01

We explore the connection between fluid capture, simulation and proximal methods, a class of algorithms commonly used for inverse problems in image processing and computer vision. Our key finding is that the proximal operator constraining fluid velocities to be divergence-free is directly equivalent to the pressure-projection methods commonly used in incompressible flow solvers. This observation lets us treat the inverse problem of fluid tracking as a constrained flow problem all while working in an efficient, modular framework. In addition it lets us tightly couple fluid simulation into flow tracking, providing a global prior that significantly increases tracking accuracy and temporal coherence as compared to previous techniques. We demonstrate how we can use these improved results for a variety of applications, such as re-simulation, detail enhancement, and domain modification. We furthermore give an outlook of the applications beyond fluid tracking that our proximal operator framework could enable by exploring the connection of deblurring and fluid guiding.

From capture to simulation: connecting forward and inverse problems in fluids

KAUST Repository

Gregson, James

2014-07-27

We explore the connection between fluid capture, simulation and proximal methods, a class of algorithms commonly used for inverse problems in image processing and computer vision. Our key finding is that the proximal operator constraining fluid velocities to be divergence-free is directly equivalent to the pressure-projection methods commonly used in incompressible flow solvers. This observation lets us treat the inverse problem of fluid tracking as a constrained flow problem all while working in an efficient, modular framework. In addition it lets us tightly couple fluid simulation into flow tracking, providing a global prior that significantly increases tracking accuracy and temporal coherence as compared to previous techniques. We demonstrate how we can use these improved results for a variety of applications, such as re-simulation, detail enhancement, and domain modification. We furthermore give an outlook of the applications beyond fluid tracking that our proximal operator framework could enable by exploring the connection of deblurring and fluid guiding.

Improving IMRT delivery efficiency with reweighted L1-minimization for inverse planning

International Nuclear Information System (INIS)

Kim, Hojin; Becker, Stephen; Lee, Rena; Lee, Soonhyouk; Shin, Sukyoung; Candès, Emmanuel; Xing Lei; Li Ruijiang

2013-01-01

Purpose: This study presents an improved technique to further simplify the fluence-map in intensity modulated radiation therapy (IMRT) inverse planning, thereby reducing plan complexity and improving delivery efficiency, while maintaining the plan quality.Methods: First-order total-variation (TV) minimization (min.) based on L1-norm has been proposed to reduce the complexity of fluence-map in IMRT by generating sparse fluence-map variations. However, with stronger dose sparing to the critical structures, the inevitable increase in the fluence-map complexity can lead to inefficient dose delivery. Theoretically, L0-min. is the ideal solution for the sparse signal recovery problem, yet practically intractable due to its nonconvexity of the objective function. As an alternative, the authors use the iteratively reweighted L1-min. technique to incorporate the benefits of the L0-norm into the tractability of L1-min. The weight multiplied to each element is inversely related to the magnitude of the corresponding element, which is iteratively updated by the reweighting process. The proposed penalizing process combined with TV min. further improves sparsity in the fluence-map variations, hence ultimately enhancing the delivery efficiency. To validate the proposed method, this work compares three treatment plans obtained from quadratic min. (generally used in clinic IMRT), conventional TV min., and our proposed reweighted TV min. techniques, implemented by a large-scale L1-solver (template for first-order conic solver), for five patient clinical data. Criteria such as conformation number (CN), modulation index (MI), and estimated treatment time are employed to assess the relationship between the plan quality and delivery efficiency.Results: The proposed method yields simpler fluence-maps than the quadratic and conventional TV based techniques. To attain a given CN and dose sparing to the critical organs for 5 clinical cases, the proposed method reduces the number of segments

Improving IMRT delivery efficiency with reweighted L1-minimization for inverse planning

Energy Technology Data Exchange (ETDEWEB)

Kim, Hojin [Department of Radiation Oncology, Stanford University, Stanford, California 94305-5847 and Department of Electrical Engineering, Stanford University, Stanford, California 94305-9505 (United States); Becker, Stephen [Laboratoire Jacques-Louis Lions, Universite Pierre et Marie Curie, Paris 6, 75005 France (France); Lee, Rena; Lee, Soonhyouk [Department of Radiation Oncology, School of Medicine, Ewha Womans University, Seoul 158-710 (Korea, Republic of); Shin, Sukyoung [Medtronic CV RDN R and D, Santa Rosa, California 95403 (United States); Candes, Emmanuel [Department of Statistics, Stanford University, Stanford, California 94305-4065 (United States); Xing Lei; Li Ruijiang [Department of Radiation Oncology, Stanford University, Stanford, California 94305-5304 (United States)

2013-07-15

Purpose: This study presents an improved technique to further simplify the fluence-map in intensity modulated radiation therapy (IMRT) inverse planning, thereby reducing plan complexity and improving delivery efficiency, while maintaining the plan quality.Methods: First-order total-variation (TV) minimization (min.) based on L1-norm has been proposed to reduce the complexity of fluence-map in IMRT by generating sparse fluence-map variations. However, with stronger dose sparing to the critical structures, the inevitable increase in the fluence-map complexity can lead to inefficient dose delivery. Theoretically, L0-min. is the ideal solution for the sparse signal recovery problem, yet practically intractable due to its nonconvexity of the objective function. As an alternative, the authors use the iteratively reweighted L1-min. technique to incorporate the benefits of the L0-norm into the tractability of L1-min. The weight multiplied to each element is inversely related to the magnitude of the corresponding element, which is iteratively updated by the reweighting process. The proposed penalizing process combined with TV min. further improves sparsity in the fluence-map variations, hence ultimately enhancing the delivery efficiency. To validate the proposed method, this work compares three treatment plans obtained from quadratic min. (generally used in clinic IMRT), conventional TV min., and our proposed reweighted TV min. techniques, implemented by a large-scale L1-solver (template for first-order conic solver), for five patient clinical data. Criteria such as conformation number (CN), modulation index (MI), and estimated treatment time are employed to assess the relationship between the plan quality and delivery efficiency.Results: The proposed method yields simpler fluence-maps than the quadratic and conventional TV based techniques. To attain a given CN and dose sparing to the critical organs for 5 clinical cases, the proposed method reduces the number of segments

Path planning of master-slave manipulator using graphic simulator

International Nuclear Information System (INIS)

Lee, J. Y.; Kim, S. H.; Song, T. K.; Park, B. S.; Yoon, J. S.

2002-01-01

To handle the high level radioactive materials such as spent fuels remotely, the master-slave manipulator is generally used as a remote handling equipment in the hot cell. To analyze the motion and to implement the training system by virtual reality technology, the simulator for M-S manipulator using the computer graphics is developed. The parts are modelled in 3-D graphics, assembled, and kinematics are assigned. The inverse kinematics of the manipulator is defined, and the slave of manipulator is coupled with master by the manipulator's specification. Also, the virtual work cell is implemented in the graphical environment which is the same as the real environment and the path planning method using the function of the collision detection for a manipulator are proposed. This graphic simulator of manipulator can be effectively used in designing of the maintenance processes for the hot cell equipment and enhance the reliability of the spent fuel management

Comparison of treatments of steep and shoot generated by different inverse planning systems

International Nuclear Information System (INIS)

Perez Moreno, J. M.; Zucca Aparicio, D.; Fernandez Leton, P.; Garcia Ruiz-Zorrilla, J.; Minambres Moro, A.

2011-01-01

The problem of IMRT treatments with the technique Steep and Shoot or static is the number of segments and monitor units used in the treatment. These parameters depend largely on the inverse planning system which determines treatment. Are evaluated three commercial planning systems, with each one performing clinical dosimetry for the same series of patients. Dosimetric results are compared, UM calculated and number of segments.

WE-AB-209-02: A New Inverse Planning Framework with Principle-Based Modeling of Inter-Structural Dosimetric Tradeoffs

International Nuclear Information System (INIS)

Liu, H; Dong, P; Xing, L

2016-01-01

Purpose: Traditional radiotherapy inverse planning relies on the weighting factors to phenomenologically balance the conflicting criteria for different structures. The resulting manual trial-and-error determination of the weights has long been recognized as the most time-consuming part of treatment planning. The purpose of this work is to develop an inverse planning framework that parameterizes the inter-structural dosimetric tradeoff among with physically more meaningful quantities to simplify the search for a clinically sensible plan. Methods: A permissible dosimetric uncertainty is introduced for each of the structures to balance their conflicting dosimetric requirements. The inverse planning is then formulated as a convex feasibility problem, which aims to generate plans with acceptable dosimetric uncertainties. A sequential procedure (SP) is derived to decompose the model into three submodels to constrain the uncertainty in the planning target volume (PTV), the critical structures, and all other structures to spare, sequentially. The proposed technique is applied to plan a liver case and a head-and-neck case and compared with a conventional approach. Results: Our results show that the strategy is able to generate clinically sensible plans with little trial-and-error. In the case of liver IMRT, the fractional volumes to liver and heart above 20Gy are found to be 22% and 10%, respectively, which are 15.1% and 33.3% lower than that of the counterpart conventional plan while maintaining the same PTV coverage. The planning of the head and neck IMRT show the same level of success, with the DVHs for all organs at risk and PTV very competitive to a counterpart plan. Conclusion: A new inverse planning framework has been established. With physically more meaningful modeling of the inter-structural tradeoff, the technique enables us to substantially reduce the need for trial-and-error adjustment of the model parameters and opens new opportunities of incorporating prior

WE-AB-209-02: A New Inverse Planning Framework with Principle-Based Modeling of Inter-Structural Dosimetric Tradeoffs

Energy Technology Data Exchange (ETDEWEB)

Liu, H; Dong, P; Xing, L [Stanford University School of Medicine, Stanford, CA (United States)

2016-06-15

Purpose: Traditional radiotherapy inverse planning relies on the weighting factors to phenomenologically balance the conflicting criteria for different structures. The resulting manual trial-and-error determination of the weights has long been recognized as the most time-consuming part of treatment planning. The purpose of this work is to develop an inverse planning framework that parameterizes the inter-structural dosimetric tradeoff among with physically more meaningful quantities to simplify the search for a clinically sensible plan. Methods: A permissible dosimetric uncertainty is introduced for each of the structures to balance their conflicting dosimetric requirements. The inverse planning is then formulated as a convex feasibility problem, which aims to generate plans with acceptable dosimetric uncertainties. A sequential procedure (SP) is derived to decompose the model into three submodels to constrain the uncertainty in the planning target volume (PTV), the critical structures, and all other structures to spare, sequentially. The proposed technique is applied to plan a liver case and a head-and-neck case and compared with a conventional approach. Results: Our results show that the strategy is able to generate clinically sensible plans with little trial-and-error. In the case of liver IMRT, the fractional volumes to liver and heart above 20Gy are found to be 22% and 10%, respectively, which are 15.1% and 33.3% lower than that of the counterpart conventional plan while maintaining the same PTV coverage. The planning of the head and neck IMRT show the same level of success, with the DVHs for all organs at risk and PTV very competitive to a counterpart plan. Conclusion: A new inverse planning framework has been established. With physically more meaningful modeling of the inter-structural tradeoff, the technique enables us to substantially reduce the need for trial-and-error adjustment of the model parameters and opens new opportunities of incorporating prior

Communication Systems Simulation Laboratory (CSSL): Simulation Planning Guide

Science.gov (United States)

Schlesinger, Adam

2012-01-01

The simulation process, milestones and inputs are unknowns to first-time users of the CSSL. The Simulation Planning Guide aids in establishing expectations for both NASA and non-NASA facility customers. The potential audience for this guide includes both internal and commercial spaceflight hardware/software developers. It is intended to assist their engineering personnel in simulation planning and execution. Material covered includes a roadmap of the simulation process, roles and responsibilities of facility and user, major milestones, facility capabilities, and inputs required by the facility. Samples of deliverables, facility interfaces, and inputs necessary to define scope, cost, and schedule are included as an appendix to the guide.

Inverse Planned High-Dose-Rate Brachytherapy for Locoregionally Advanced Cervical Cancer: 4-Year Outcomes

Energy Technology Data Exchange (ETDEWEB)

Tinkle, Christopher L.; Weinberg, Vivian [Department of Radiation Oncology, University of California, San Francisco, California (United States); Chen, Lee-May [Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco, California (United States); Littell, Ramey [Gynecologic Oncology, The Permanente Medical Group, San Francisco, California (United States); Cunha, J. Adam M.; Sethi, Rajni A. [Department of Radiation Oncology, University of California, San Francisco, California (United States); Chan, John K. [Gynecologic Oncology, California Pacific Medical Center, San Francisco, California (United States); Hsu, I-Chow, E-mail: ichow.hsu@ucsf.edu [Department of Radiation Oncology, University of California, San Francisco, California (United States)

2015-08-01

Purpose: Evaluate the efficacy and toxicity of image guided brachytherapy using inverse planning simulated annealing (IPSA) high-dose-rate brachytherapy (HDRB) boost for locoregionally advanced cervical cancer. Methods and Materials: From December 2003 through September 2009, 111 patients with primary cervical cancer were treated definitively with IPSA-planned HDRB boost (28 Gy in 4 fractions) after external radiation at our institution. We performed a retrospective review of our experience using image guided brachytherapy. Of the patients, 70% had a tumor size >4 cm, 38% had regional nodal disease, and 15% had clinically evident distant metastasis, including nonregional nodal disease, at the time of diagnosis. Surgical staging involving pelvic lymph node dissection was performed in 15% of patients, and 93% received concurrent cisplatin-based chemotherapy. Toxicities are reported according to the Common Terminology Criteria for Adverse Events version 4.0 guidelines. Results: With a median follow-up time of 42 months (range, 3-84 months), no acute or late toxicities of grade 4 or higher were observed, and grade 3 toxicities (both acute and late) developed in 8 patients (1 constitutional, 1 hematologic, 2 genitourinary, 4 gastrointestinal). The 4-year Kaplan-Meier estimate of late grade 3 toxicity was 8%. Local recurrence developed in 5 patients (4 to 9 months after HDRB), regional recurrence in 3 (6, 16, and 72 months after HDRB), and locoregional recurrence in 1 (4 months after HDR boost). The 4-year estimates of local, locoregional, and distant control of disease were 94.0%, 91.9%, and 69.1%, respectively. The overall and disease-free survival rates at 4 years were 64.3% (95% confidence interval [CI] of 54%-73%) and 61.0% (95% CI, 51%-70%), respectively. Conclusions: Definitive radiation by use of inverse planned HDRB boost for locoregionally advanced cervical cancer is well tolerated and achieves excellent local control of disease. However, overall

hp-HGS strategy for inverse 3D DC resistivity logging measurement simulations

KAUST Repository

Gajda-Zaǵorska, Ewa; Paszý nski, Maciej; Schaefer, Robert; Pardo, David; Calo, Victor M.

2012-01-01

In this paper we present a twin adaptive strategy hp-HGS for solving inverse problems related to 3D DC borehole resistivity measurement simulations. The term “simulation of measurements” is widely used by the geophysical community. A quantity of interest, voltage, is measured at a receiver electrode located in the logging instrument. We use the self-adaptive goal-oriented hp-Finite Element Method (hp-FEM) computer simulations of the process of measurements in deviated wells (when the angle between the borehole and formation layers are < 90 deg). We also employ the hierarchical genetic search (HGS) algorithm to solve the inverse problem. Each individual in the population represents a single configuration of the formation layers. The evaluation of the individual is performed by solving the direct problem by means of the hp-FEM algorithm and by comparison with measured logging curve. We conclude the paper with some discussion on the parallelization of the algorithm.

hp-HGS strategy for inverse 3D DC resistivity logging measurement simulations

KAUST Repository

Gajda-Zaǵorska, Ewa

2012-06-02

In this paper we present a twin adaptive strategy hp-HGS for solving inverse problems related to 3D DC borehole resistivity measurement simulations. The term “simulation of measurements” is widely used by the geophysical community. A quantity of interest, voltage, is measured at a receiver electrode located in the logging instrument. We use the self-adaptive goal-oriented hp-Finite Element Method (hp-FEM) computer simulations of the process of measurements in deviated wells (when the angle between the borehole and formation layers are < 90 deg). We also employ the hierarchical genetic search (HGS) algorithm to solve the inverse problem. Each individual in the population represents a single configuration of the formation layers. The evaluation of the individual is performed by solving the direct problem by means of the hp-FEM algorithm and by comparison with measured logging curve. We conclude the paper with some discussion on the parallelization of the algorithm.

New inverse planning technology for image-guided cervical cancer brachytherapy: Description and evaluation within a clinical frame

International Nuclear Information System (INIS)

Trnkova, Petra; Poetter, Richard; Baltas, Dimos; Karabis, Andreas; Fidarova, Elena; Dimopoulos, Johannes; Georg, Dietmar; Kirisits, Christian

2009-01-01

Purpose: To test the feasibility of a new inverse planning technology based on the Hybrid Inverse treatment Planning and Optimisation (HIPO) algorithm for image-guided cervical cancer brachytherapy in comparison to conventional manual optimisation as applied in recent clinical practice based on long-term intracavitary cervical cancer brachytherapy experience. Materials and methods: The clinically applied treatment plans of 10 tandem/ring (T/R) and 10 cases with additional needles (T/R + N) planned with PLATO v14.3 were included. Standard loading patterns were manually optimised to reach an optimal coverage with 7 Gy per fraction to the High Risk CTV and to fulfil dose constraints for organs at risk. For each of these patients an inverse plan was retrospectively created with Oncentra GYN v0.9.14. Anatomy based automatic source activation was based on the topography of target and organs. The HIPO algorithm included individual gradient and modification restrictions for the T/R and needle dwell times to preserve the spatial high-dose distribution as known from the long-term clinical experience in the standard cervical cancer brachytherapy and with manual planning. Results: HIPO could achieve a better target coverage (V100) for all T/R and 7 T/R + N patients. Changes in the shape of the overdose volume (V200/400) were limited. The D 2cc per fraction for bladder, rectum and sigmoid colon was on average lower by 0.2 Gy, 0.4 Gy, 0.2 Gy, respectively, for T/R patients and 0.6 Gy, 0.3 Gy, 0.3 Gy for T/R + N patients (a decrease from 4.5 to 4 Gy per fraction means a total dose reduction of 5 Gy EQD2 for a 4-fraction schedule). In general the dwell times in the additional needles were lower compared to manual planning. The sparing factors were always better for HIPO plans. Additionally, in 7 T/R and 7 T/R + N patients all three D 0.1cc , D 1cc and D 2cc for vagina wall were lower and a smaller area of vagina was covered by the reference dose in HIPO plans. Overall loading

Incorporating model parameter uncertainty into inverse treatment planning

International Nuclear Information System (INIS)

Lian Jun; Xing Lei

2004-01-01

Radiobiological treatment planning depends not only on the accuracy of the models describing the dose-response relation of different tumors and normal tissues but also on the accuracy of tissue specific radiobiological parameters in these models. Whereas the general formalism remains the same, different sets of model parameters lead to different solutions and thus critically determine the final plan. Here we describe an inverse planning formalism with inclusion of model parameter uncertainties. This is made possible by using a statistical analysis-based frameset developed by our group. In this formalism, the uncertainties of model parameters, such as the parameter a that describes tissue-specific effect in the equivalent uniform dose (EUD) model, are expressed by probability density function and are included in the dose optimization process. We found that the final solution strongly depends on distribution functions of the model parameters. Considering that currently available models for computing biological effects of radiation are simplistic, and the clinical data used to derive the models are sparse and of questionable quality, the proposed technique provides us with an effective tool to minimize the effect caused by the uncertainties in a statistical sense. With the incorporation of the uncertainties, the technique has potential for us to maximally utilize the available radiobiology knowledge for better IMRT treatment

Inverse simulated annealing: Improvements and application to amorphous InSb

OpenAIRE

Los, Jan H.; Gabardi, Silvia; Bernasconi, Marco; Kühne, Thomas D.

2014-01-01

An improved inverse simulated annealing method is presented to determine the structure of complex disordered systems from first principles in agreement with available experimental data or desired predetermined target properties. The effectiveness of this method is demonstrated by revisiting the structure of amorphous InSb. The resulting network is mostly tetrahedral and in excellent agreement with available experimental data.

Functional avoidance of lung in plan optimization with an aperture-based inverse planning system

International Nuclear Information System (INIS)

St-Hilaire, Jason; Lavoie, Caroline; Dagnault, Anne; Beaulieu, Frederic; Morin, Francis; Beaulieu, Luc; Tremblay, Daniel

2011-01-01

Purpose: To implement SPECT-based optimization in an anatomy-based aperture inverse planning system for the functional avoidance of lung in thoracic irradiation. Material and methods: SPECT information has been introduced as a voxel-by-voxel modulation of lung importance factors proportionally to the local perfusion count. Fifteen cases of lung cancer have been retrospectively analyzed by generating angle-optimized non-coplanar plans, comparing a purely anatomical approach and our functional approach. Planning target volume coverage and lung sparing have been compared. Statistical significance was assessed by a Wilcoxon matched pairs test. Results: For similar target coverage, perfusion-weighted volume receiving 10 Gy was reduced by a median of 2.2% (p = 0.022) and mean perfusion-weighted lung dose, by a median of 0.9 Gy (p = 0.001). A separate analysis of patients with localized or non-uniform hypoperfusion could not show which would benefit more from SPECT-based treatment planning. Redirection of dose sometimes created overdosage regions in the target volume. Plans consisted of a similar number of segments and monitor units. Conclusions: Angle optimization and SPECT-based modulation of importance factors allowed for functional avoidance of the lung while preserving target coverage. The technique could be also applied to implement PET-based modulation inside the target volume, leading to a safer dose escalation.

Simulation of atmospheric temperature inversions over greater cairo using the MM5 Meso-Scale atmospheric model

International Nuclear Information System (INIS)

Kandil, H.A.; Elhadidi, B.M.; Kader, A. A.; Moaty, A.A.; Sherif, A.O.

2006-01-01

Air pollution episodes have been recorded in Cairo, during the fall season, since 1999, as a result of specific meteorological conditions combined with large quantity of pollutants created by several ground-based sources. The main reason for the smog-like episodes (black clouds) is adverse weather conditions with low and variable winds, high humidity and strong temperature inversions in the few-hundred meters above the ground. The two important types of temperature inversion affecting the air pollution are surface or ground (radiation) inversion and subsidence (elevated) inversion. The surface temperature inversion is associated with a rapid decrease in the ground surface temperature with the simultaneous existence of warm air in the lower troposphere. The inversion develops at dusk and continues until the surface warms again the following day. Pollutants emitted during the night are caught under this i nversion lid. S ubsidence inversion forms when warm air masses move over colder air masses. The inversion develops with a stagnating high-pressure system (generally associated with fair weather). Under these conditions, the pressure gradient becomes progressively weaker so that winds become light. These light winds greatly reduce the horizontal transport and dispersion of pollutants. At the same time, the subsidence inversion acts as a barrier to the vertical dispersion of the pollutants. In this study, the Penn State/NCAR meso -scale model (MM5) is used to simulate the temperature inversion phenomenon over Greater Cairo region during the fall season of 2004. Accurate computations of the heat transfer at the surface are needed to capture this phenomenon. This can only be achieved by high-resolution simulations in both horizontal and vertical directions. Hence, for accurate simulation of the temperature inversion over Greater Cairo, four nested domains of resolutions of 27 km, 9 km, 3 km and 1 km, respectively, were used in the horizontal planes. Furthermore, 42

Stereotactic intensity-modulated radiation therapy (IMRT) and inverse treatment planning for advanced pleural mesothelioma. Feasibility and initial results

Energy Technology Data Exchange (ETDEWEB)

Muenter, M.W.; Thilmann, C.; Hof, H.; Debus, J. [Clinical Cooperation Unit Radiation Oncology, German Cancer Research Center (dkfz), Heidelberg (Germany); Nill, S.; Hoess, A.; Partridge, M. [Dept. of Medical Physics, German Cancer Research Center (dkfz), Heidelberg (Germany); Haering, P. [Dept. of Central Dosimetry, German Cancer Research Center (dkfz), Heidelberg (Germany); Manegold, C. [Dept. of Medical Oncology/Internal Medicine, Thoraxklinik Heidelberg gGmbH, Heidelberg (Germany); Wannenmacher, M. [Dept. of Clinical Radiology, Univ. of Heidelberg, Heidelberg (Germany)

2003-08-01

Background and Purpose: Complex-shaped malignant pleural mesotheliomas (MPMs) with challenging volumes are extremely difficult to treat by conventional radiotherapy due to tolerance doses of the surrounding normal tissue. In a feasibility study, we evaluated if inversely planned stereotactic intensity-modulated radiation therapy (IMRT) could be applied in the treatment of MPM. Patients and Methods: Eight patients with unresectable lesions were treated after failure of chemotherapy. All patients were positioned using noninvasive patient fixation techniques which can be attached to the applied extracranial stereotactic system. Due to craniocaudal extension of the tumor, it was necessary to develop a special software attached to the inverse planning program KonRad, which can connect two inverse treatment plans and consider the applied dose of the first treatment plan in the area of the matchline of the second treatment plan. Results: Except for one patient, in whom radiotherapy was canceled due to abdominal metastasis, treatment could be completed in all patients and was well tolerated. Median survival after diagnosis was 20 months and after IMRT 6.5 months. Therefore, both the 1-year actuarial overall survival from the start of radiotherapy and the 2-year actuarial overall survival since diagnosis were 28%. IMRT did not result in clinically significant acute side effects. By using the described inverse planning software, over- or underdosage in the region of the field matchline could be prevented. Pure treatment time ranged between 10 and 21 min. Conclusion: This study showed that IMRT is feasible in advanced unresectable MPM. The presented possibilities of stereotactic IMRT in the treatment of MPM will justify the evaluation of IMRT in early-stage pleural mesothelioma combined with chemotherapy in a study protocol, in order to improve the outcome of these patients. Furthermore, dose escalation should be possible by using IMRT. (orig.)

Planning Study Comparison of Real-Time Target Tracking and Four-Dimensional Inverse Planning for Managing Patient Respiratory Motion

International Nuclear Information System (INIS)

Zhang Peng; Hugo, Geoffrey D.; Yan Di

2008-01-01

Purpose: Real-time target tracking (RT-TT) and four-dimensional inverse planning (4D-IP) are two potential methods to manage respiratory target motion. In this study, we evaluated each method using the cumulative dose-volume criteria in lung cancer radiotherapy. Methods and Materials: Respiration-correlated computed tomography scans were acquired for 4 patients. Deformable image registration was applied to generate a displacement mapping for each phase image of the respiration-correlated computed tomography images. First, the dose distribution for the organs of interest obtained from an idealized RT-TT technique was evaluated, assuming perfect knowledge of organ motion and beam tracking. Inverse planning was performed on each phase image separately. The treatment dose to the organs of interest was then accumulated from the optimized plans. Second, 4D-IP was performed using the probability density function of respiratory motion. The beam arrangement, prescription dose, and objectives were consistent in both planning methods. The dose-volume and equivalent uniform dose in the target volume, lung, heart, and spinal cord were used for the evaluation. Results: The cumulative dose in the target was similar for both techniques. The equivalent uniform dose of the lung, heart, and spinal cord was 4.6 ± 2.2, 11 ± 4.4, and 11 ± 6.6 Gy for RT-TT with a 0-mm target margin, 5.2 ± 3.1, 12 ± 5.9, and 12 ± 7.8 Gy for RT-TT with a 2-mm target margin, and 5.3 ± 2.3, 11.9 ± 5.0, and 12 ± 5.6 Gy for 4D-IP, respectively. Conclusion: The results of our study have shown that 4D-IP can achieve plans similar to those achieved by RT-TT. Considering clinical implementation, 4D-IP could be a more reliable and practical method to manage patient respiration-induced motion

A design of inverse Taylor projectiles using material simulation

International Nuclear Information System (INIS)

Tonks, Michael; Harstad, Eric; Maudlin, Paul; Trujillo, Carl

2008-01-01

The classic Taylor cylinder test, in which a right circular cylinder is projected at a rigid anvil, exploits the inertia of the projectile to access strain rates that are difficult to achieve with more traditional uniaxial testing methods. In this work we present our efforts to design inverse Taylor projectiles, in which a tapered projectile becomes a right circular cylinder after impact, from annealed copper and show that the self-correcting geometry leads to a uniform compressive strain in the radial direction. We design projectiles using finite element simulation and optimization that deform as desired in tests with minor deviations in the deformed geometry due to manufacturing error and uncertainty in the initial velocity. The inverse Taylor projectiles designed in this manner provide a simple means of validating constitutive models. This work is a step towards developing a general method of designing Taylor projectiles that provide stress–strain behavior relevant to particular engineering problems

Dose-volume and biological-model based comparison between helical tomotherapy and (inverse-planned) IMAT for prostate tumours

International Nuclear Information System (INIS)

Iori, Mauro; Cattaneo, Giovanni Mauro; Cagni, Elisabetta; Fiorino, Claudio; Borasi, Gianni; Riccardo, Calandrino; Iotti, Cinzia; Fazio, Ferruccio; Nahum, Alan E.

2008-01-01

Background and purpose: Helical tomotherapy (HT) and intensity-modulated arc therapy (IMAT) are two arc-based approaches to the delivery of intensity-modulated radiotherapy (IMRT). Through plan comparisons we have investigated the potential of IMAT, both with constant (conventional or IMAT-C) and variable (non-conventional or IMAT-NC, a theoretical exercise) dose-rate, to serve as an alternative to helical tomotherapy. Materials and methods: Six patients with prostate tumours treated by HT with a moderately hypo-fractionated protocol, involving a simultaneous integrated boost, were re-planned as IMAT treatments. A method for IMAT inverse-planning using a commercial module for static IMRT combined with a multi-leaf collimator (MLC) arc-sequencing was developed. IMAT plans were compared to HT plans in terms of dose statistics and radiobiological indices. Results: Concerning the planning target volume (PTV), the mean doses for all PTVs were similar for HT and IMAT-C plans with minimum dose, target coverage, equivalent uniform dose (EUD) and tumour control probability (TCP) values being generally higher for HT; maximum dose and degree of heterogeneity were instead higher for IMAT-C. In relation to organs at risk, mean doses and normal tissue complication probability (NTCP) values were similar between the two modalities, except for the penile bulb where IMAT was significantly better. Re-normalizing all plans to the same rectal toxicity (NTCP = 5%), the HT modality yielded higher TCP than IMAT-C but there was no significant difference between HT and IMAT-NC. The integral dose with HT was higher than that for IMAT. Conclusions: with regards to the plan analysis, the HT is superior to IMAT-C in terms of target coverage and dose homogeneity within the PTV. Introducing dose-rate variation during arc-rotation, not deliverable with current linac technology, the simulations result in comparable plan indices between (IMAT-NC) and HT

An improved fast and elitist multi-objective genetic algorithm-ANSGA-II for multi-objective optimization of inverse radiotherapy treatment planning

International Nuclear Information System (INIS)

Cao Ruifen; Li Guoli; Song Gang; Zhao Pan; Lin Hui; Wu Aidong; Huang Chenyu; Wu Yican

2007-01-01

Objective: To provide a fast and effective multi-objective optimization algorithm for inverse radiotherapy treatment planning system. Methods: Non-dominated Sorting Genetic Algorithm-NSGA-II is a representative of multi-objective evolutionary optimization algorithms and excels the others. The paper produces ANSGA-II that makes use of advantage of NSGA-II, and uses adaptive crossover and mutation to improve its flexibility; according the character of inverse radiotherapy treatment planning, the paper uses the pre-known knowledge to generate individuals of every generation in the course of optimization, which enhances the convergent speed and improves efficiency. Results: The example of optimizing average dose of a sheet of CT, including PTV, OAR, NT, proves the algorithm could find satisfied solutions in several minutes. Conclusions: The algorithm could provide clinic inverse radiotherapy treatment planning system with selection of optimization algorithms. (authors)

Does inverse-planned intensity-modulated radiation therapy have a role in the treatment of patients with left-sided breast cancer?

International Nuclear Information System (INIS)

Stillie, Alison L.; Chua, Boon; Kron, Tomas; Cramb, Jim; Herschtal, Alan; Hornby, Colin; Sullivan, Kelly

2011-01-01

The purpose of the study was to determine if multi-field inverse-planned intensity-modulated radiation therapy (IMRT) improves on the sparing of organs at risk (heart, lungs and contralateral breast) when compared with field-in-field forward-planned RT (FiF). The planning CT scans of 10 women with left-sided breast cancer previously treated with whole-breast RT on an inclined breast board with both arms supported above the head were retrieved. The whole breast planning target volume (PTV) was defined by clinical mark-up and contoured on all relevant CT slices as were the organs at risk. For each patient, three plans were generated using FiF, five- and nine-field inverse-planned IMRT, all to a total dose of 50 Gy to the whole breast. Mean and maximum doses to the organs at risk and the homogeneity index (HI) of the whole-breast PTV were compared. The mean heart dose for the FiF plans was 2.63 Gy compared with 4.04 Gy for the five-field and 4.30 Gy for the nine-field IMRT plans, with no significant differences in the HI of the whole-breast PTV in all plans. The FiF plans resulted in a mean contralateral breast dose of 0.58 Gy compared with 0.70 and 2.08 Gy for the five- and nine-field IMRT plans, respectively. FiF resulted in a lower mean heart and contralateral breast dose with comparable HI of the whole-breast PTV in comparison with inverse-planned IMRT using five or nine fields.

Four dimensional data assimilation (FDDA) impacts on WRF performance in simulating inversion layer structure and distributions of CMAQ-simulated winter ozone concentrations in Uintah Basin

Science.gov (United States)

Tran, Trang; Tran, Huy; Mansfield, Marc; Lyman, Seth; Crosman, Erik

2018-03-01

Four-dimensional data assimilation (FDDA) was applied in WRF-CMAQ model sensitivity tests to study the impact of observational and analysis nudging on model performance in simulating inversion layers and O3 concentration distributions within the Uintah Basin, Utah, U.S.A. in winter 2013. Observational nudging substantially improved WRF model performance in simulating surface wind fields, correcting a 10 °C warm surface temperature bias, correcting overestimation of the planetary boundary layer height (PBLH) and correcting underestimation of inversion strengths produced by regular WRF model physics without nudging. However, the combined effects of poor performance of WRF meteorological model physical parameterization schemes in simulating low clouds, and warm and moist biases in the temperature and moisture initialization and subsequent simulation fields, likely amplified the overestimation of warm clouds during inversion days when observational nudging was applied, impacting the resulting O3 photochemical formation in the chemistry model. To reduce the impact of a moist bias in the simulations on warm cloud formation, nudging with the analysis water mixing ratio above the planetary boundary layer (PBL) was applied. However, due to poor analysis vertical temperature profiles, applying analysis nudging also increased the errors in the modeled inversion layer vertical structure compared to observational nudging. Combining both observational and analysis nudging methods resulted in unrealistically extreme stratified stability that trapped pollutants at the lowest elevations at the center of the Uintah Basin and yielded the worst WRF performance in simulating inversion layer structure among the four sensitivity tests. The results of this study illustrate the importance of carefully considering the representativeness and quality of the observational and model analysis data sets when applying nudging techniques within stable PBLs, and the need to evaluate model results

Sensitivity study on hydraulic well testing inversion using simulated annealing

International Nuclear Information System (INIS)

Nakao, Shinsuke; Najita, J.; Karasaki, Kenzi

1997-11-01

For environmental remediation, management of nuclear waste disposal, or geothermal reservoir engineering, it is very important to evaluate the permeabilities, spacing, and sizes of the subsurface fractures which control ground water flow. Cluster variable aperture (CVA) simulated annealing has been used as an inversion technique to construct fluid flow models of fractured formations based on transient pressure data from hydraulic tests. A two-dimensional fracture network system is represented as a filled regular lattice of fracture elements. The algorithm iteratively changes an aperture of cluster of fracture elements, which are chosen randomly from a list of discrete apertures, to improve the match to observed pressure transients. The size of the clusters is held constant throughout the iterations. Sensitivity studies using simple fracture models with eight wells show that, in general, it is necessary to conduct interference tests using at least three different wells as pumping well in order to reconstruct the fracture network with a transmissivity contrast of one order of magnitude, particularly when the cluster size is not known a priori. Because hydraulic inversion is inherently non-unique, it is important to utilize additional information. The authors investigated the relationship between the scale of heterogeneity and the optimum cluster size (and its shape) to enhance the reliability and convergence of the inversion. It appears that the cluster size corresponding to about 20--40 % of the practical range of the spatial correlation is optimal. Inversion results of the Raymond test site data are also presented and the practical range of spatial correlation is evaluated to be about 5--10 m from the optimal cluster size in the inversion

Sensitivity study on hydraulic well testing inversion using simulated annealing

Energy Technology Data Exchange (ETDEWEB)

Nakao, Shinsuke; Najita, J.; Karasaki, Kenzi

1997-11-01

For environmental remediation, management of nuclear waste disposal, or geothermal reservoir engineering, it is very important to evaluate the permeabilities, spacing, and sizes of the subsurface fractures which control ground water flow. Cluster variable aperture (CVA) simulated annealing has been used as an inversion technique to construct fluid flow models of fractured formations based on transient pressure data from hydraulic tests. A two-dimensional fracture network system is represented as a filled regular lattice of fracture elements. The algorithm iteratively changes an aperture of cluster of fracture elements, which are chosen randomly from a list of discrete apertures, to improve the match to observed pressure transients. The size of the clusters is held constant throughout the iterations. Sensitivity studies using simple fracture models with eight wells show that, in general, it is necessary to conduct interference tests using at least three different wells as pumping well in order to reconstruct the fracture network with a transmissivity contrast of one order of magnitude, particularly when the cluster size is not known a priori. Because hydraulic inversion is inherently non-unique, it is important to utilize additional information. The authors investigated the relationship between the scale of heterogeneity and the optimum cluster size (and its shape) to enhance the reliability and convergence of the inversion. It appears that the cluster size corresponding to about 20--40 % of the practical range of the spatial correlation is optimal. Inversion results of the Raymond test site data are also presented and the practical range of spatial correlation is evaluated to be about 5--10 m from the optimal cluster size in the inversion.

Improve earthquake hypocenter using adaptive simulated annealing inversion in regional tectonic, volcano tectonic, and geothermal observation

Energy Technology Data Exchange (ETDEWEB)

Ry, Rexha Verdhora, E-mail: rexha.vry@gmail.com [Master Program of Geophysical Engineering, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Jalan Ganesha No.10, Bandung 40132 (Indonesia); Nugraha, Andri Dian, E-mail: nugraha@gf.itb.ac.id [Global Geophysical Research Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Jalan Ganesha No.10, Bandung 40132 (Indonesia)

2015-04-24

Observation of earthquakes is routinely used widely in tectonic activity observation, and also in local scale such as volcano tectonic and geothermal activity observation. It is necessary for determining the location of precise hypocenter which the process involves finding a hypocenter location that has minimum error between the observed and the calculated travel times. When solving this nonlinear inverse problem, simulated annealing inversion method can be applied to such global optimization problems, which the convergence of its solution is independent of the initial model. In this study, we developed own program codeby applying adaptive simulated annealing inversion in Matlab environment. We applied this method to determine earthquake hypocenter using several data cases which are regional tectonic, volcano tectonic, and geothermal field. The travel times were calculated using ray tracing shooting method. We then compared its results with the results using Geiger’s method to analyze its reliability. Our results show hypocenter location has smaller RMS error compared to the Geiger’s result that can be statistically associated with better solution. The hypocenter of earthquakes also well correlated with geological structure in the study area. Werecommend using adaptive simulated annealing inversion to relocate hypocenter location in purpose to get precise and accurate earthquake location.

The incorporation of SPECT functional lung imaging into inverse radiotherapy planning for non-small cell lung cancer

International Nuclear Information System (INIS)

Christian, Judith A.; Partridge, Mike; Nioutsikou, Elena; Cook, Gary; McNair, Helen A.; Cronin, Bernadette; Courbon, Frederic; Bedford, James L.; Brada, Michael

2005-01-01

Background and purpose: Patients with non-small cell lung cancer (NSCLC) often have inhomogeneous lung perfusion. Radiotherapy planning computed tomography (CT) scans have been accurately co-registered with lung perfusion single photon emission computed tomography (SPECT) scans to design radiotherapy treatments which limit dose to healthy 'perfused' lung. Patients and methods: Patients with localised NSCLC had CT and SPECT scans accurately co-registered in the planning system. The SPECT images were used to define a volume of perfused 'functioning' lung (FL). Inverse planning software was used to create 3D-conformal plans, the planning objective being either to minimise the dose to whole lungs (WL) or to minimise the dose to FL. Results: Four plans were created for each of six patients. The mean difference in volume between WL and FL was 1011.7 cm 3 (range 596.2-1581.1 cm 3 ). One patient with bilateral upper lobe perfusion deficits had a 16% reduction in FLV 2 (the percentage volume of functioning lung receiving ≥20 Gy). The remaining patients had inhomogeneous perfusion deficits such that inverse planning was not able to sufficiently optimise beam angles to avoid functioning lung. Conclusion: SPECT perfusion images can be accurately co-registered with radiotherapy planning CT scans and may be helpful in creating treatment plans for patients with large perfusion deficits

From physical dose constraints to equivalent uniform dose constraints in inverse radiotherapy planning

International Nuclear Information System (INIS)

Thieke, Christian; Bortfeld, Thomas; Niemierko, Andrzej; Nill, Simeon

2003-01-01

Optimization algorithms in inverse radiotherapy planning need information about the desired dose distribution. Usually the planner defines physical dose constraints for each structure of the treatment plan, either in form of minimum and maximum doses or as dose-volume constraints. The concept of equivalent uniform dose (EUD) was designed to describe dose distributions with a higher clinical relevance. In this paper, we present a method to consider the EUD as an optimization constraint by using the method of projections onto convex sets (POCS). In each iteration of the optimization loop, for the actual dose distribution of an organ that violates an EUD constraint a new dose distribution is calculated that satisfies the EUD constraint, leading to voxel-based physical dose constraints. The new dose distribution is found by projecting the current one onto the convex set of all dose distributions fulfilling the EUD constraint. The algorithm is easy to integrate into existing inverse planning systems, and it allows the planner to choose between physical and EUD constraints separately for each structure. A clinical case of a head and neck tumor is optimized using three different sets of constraints: physical constraints for all structures, physical constraints for the target and EUD constraints for the organs at risk, and EUD constraints for all structures. The results show that the POCS method converges stable and given EUD constraints are reached closely

Power system restoration: planning and simulation

Energy Technology Data Exchange (ETDEWEB)

Hazarika, D. [Assam Engineering Coll., Dept. of Electrical Engineering, Assam (India); Sinha, A.K. [Inidan Inst. of Technology, Dept. of Electrical Engineering, Kharagpur (India)

2003-03-01

This paper describes a restoration guidance simulator, which allows power system operator/planner to simulate and plan restoration events in an interactive mode. The simulator provides a list of restoration events according to the priority based on some restoration rules and list of priority loads. It also provides in an interactive mode the list of events, which becomes possible as the system grows during restoration. Further, the selected event is validated through a load flow and other analytical tools to show the consequences of implementing the planned event. (Author)

Inverse uncertainty quantification of reactor simulations under the Bayesian framework using surrogate models constructed by polynomial chaos expansion

Energy Technology Data Exchange (ETDEWEB)

Wu, Xu, E-mail: xuwu2@illinois.edu; Kozlowski, Tomasz

2017-03-15

Modeling and simulations are naturally augmented by extensive Uncertainty Quantification (UQ) and sensitivity analysis requirements in the nuclear reactor system design, in which uncertainties must be quantified in order to prove that the investigated design stays within acceptance criteria. Historically, expert judgment has been used to specify the nominal values, probability density functions and upper and lower bounds of the simulation code random input parameters for the forward UQ process. The purpose of this paper is to replace such ad-hoc expert judgment of the statistical properties of input model parameters with inverse UQ process. Inverse UQ seeks statistical descriptions of the model random input parameters that are consistent with the experimental data. Bayesian analysis is used to establish the inverse UQ problems based on experimental data, with systematic and rigorously derived surrogate models based on Polynomial Chaos Expansion (PCE). The methods developed here are demonstrated with the Point Reactor Kinetics Equation (PRKE) coupled with lumped parameter thermal-hydraulics feedback model. Three input parameters, external reactivity, Doppler reactivity coefficient and coolant temperature coefficient are modeled as uncertain input parameters. Their uncertainties are inversely quantified based on synthetic experimental data. Compared with the direct numerical simulation, surrogate model by PC expansion shows high efficiency and accuracy. In addition, inverse UQ with Bayesian analysis can calibrate the random input parameters such that the simulation results are in a better agreement with the experimental data.

Development of a neuro-fuzzy technique for automated parameter optimization of inverse treatment planning

International Nuclear Information System (INIS)

Stieler, Florian; Yan, Hui; Lohr, Frank; Wenz, Frederik; Yin, Fang-Fang

2009-01-01

Parameter optimization in the process of inverse treatment planning for intensity modulated radiation therapy (IMRT) is mainly conducted by human planners in order to create a plan with the desired dose distribution. To automate this tedious process, an artificial intelligence (AI) guided system was developed and examined. The AI system can automatically accomplish the optimization process based on prior knowledge operated by several fuzzy inference systems (FIS). Prior knowledge, which was collected from human planners during their routine trial-and-error process of inverse planning, has first to be 'translated' to a set of 'if-then rules' for driving the FISs. To minimize subjective error which could be costly during this knowledge acquisition process, it is necessary to find a quantitative method to automatically accomplish this task. A well-developed machine learning technique, based on an adaptive neuro fuzzy inference system (ANFIS), was introduced in this study. Based on this approach, prior knowledge of a fuzzy inference system can be quickly collected from observation data (clinically used constraints). The learning capability and the accuracy of such a system were analyzed by generating multiple FIS from data collected from an AI system with known settings and rules. Multiple analyses showed good agreements of FIS and ANFIS according to rules (error of the output values of ANFIS based on the training data from FIS of 7.77 ± 0.02%) and membership functions (3.9%), thus suggesting that the 'behavior' of an FIS can be propagated to another, based on this process. The initial experimental results on a clinical case showed that ANFIS is an effective way to build FIS from practical data, and analysis of ANFIS and FIS with clinical cases showed good planning results provided by ANFIS. OAR volumes encompassed by characteristic percentages of isodoses were reduced by a mean of between 0 and 28%. The study demonstrated a feasible way

Development of a neuro-fuzzy technique for automated parameter optimization of inverse treatment planning

Directory of Open Access Journals (Sweden)

Wenz Frederik

2009-09-01

Full Text Available Abstract Background Parameter optimization in the process of inverse treatment planning for intensity modulated radiation therapy (IMRT is mainly conducted by human planners in order to create a plan with the desired dose distribution. To automate this tedious process, an artificial intelligence (AI guided system was developed and examined. Methods The AI system can automatically accomplish the optimization process based on prior knowledge operated by several fuzzy inference systems (FIS. Prior knowledge, which was collected from human planners during their routine trial-and-error process of inverse planning, has first to be "translated" to a set of "if-then rules" for driving the FISs. To minimize subjective error which could be costly during this knowledge acquisition process, it is necessary to find a quantitative method to automatically accomplish this task. A well-developed machine learning technique, based on an adaptive neuro fuzzy inference system (ANFIS, was introduced in this study. Based on this approach, prior knowledge of a fuzzy inference system can be quickly collected from observation data (clinically used constraints. The learning capability and the accuracy of such a system were analyzed by generating multiple FIS from data collected from an AI system with known settings and rules. Results Multiple analyses showed good agreements of FIS and ANFIS according to rules (error of the output values of ANFIS based on the training data from FIS of 7.77 ± 0.02% and membership functions (3.9%, thus suggesting that the "behavior" of an FIS can be propagated to another, based on this process. The initial experimental results on a clinical case showed that ANFIS is an effective way to build FIS from practical data, and analysis of ANFIS and FIS with clinical cases showed good planning results provided by ANFIS. OAR volumes encompassed by characteristic percentages of isodoses were reduced by a mean of between 0 and 28%. Conclusion The

Inverse treatment planning for intensity modulated radiation therapy: CDVH treatment prescription with integral cost function

International Nuclear Information System (INIS)

Carol, M.P.; Nash, R.; Campbell, R.C.; Huber, R.

1997-01-01

Purpose/Objective: Inverse planning is a required approach when dealing with the complexity of variables present in an intensity modulated plan. However, an inverse planning system is only as useful as it is 1) easy to use and 2) predictable in its result. This is especially the case when the target goals and structure limits specified by the user all cannot be achieved. We have previously developed two interfaces for specifying how such conflicts should be resolved when they occur, that, although allowing a range of results to be obtained, still require 'trial and error' on the part of the user and are case dependent. A new method is explored with goals of allowing the desired results to be specified in an intuitive manner and producing predictable results that are case independent. Materials and Methods: Target goals and structure limits are specified by entering partial volume data: goal/limit, % under/over goal/limit, minimum, maximum. This data is converted to a CDVH curve for each target/structure. During the simulated annealing process used to produce an optimized solution, the actual CDVHs are compared to the desired CDVHs after each iteration and a cost is computed for the difference between the curves. For each curve, the cost is proportional to the difference in area between the desired and actual curves. This cost is controlled by three variables: offset (amount of difference before there is any cost), scale (the range the cost can take) and shape (the shape of the curve for difference versus cost). A range of values were explored for these variables in order to determine if predictable trade-offs would be made automatically by the system. The cost function was tested against a range of cases: a highly irregularly shaped intracranial lesion, a head and neck case with three target volumes with different prescriptions, and a prostate cancer. Results: By varying the values assigned to the control variables, a variety of predictable results could be

Mixed integer programming improves comprehensibility and plan quality in inverse optimization of prostate HDR Brachytherapy

NARCIS (Netherlands)

Gorissen, B.L.; den Hertog, D.; Hoffmann, A.L.

2013-01-01

Current inverse treatment planning methods that optimize both catheter positions and dwell times in prostate HDR brachytherapy use surrogate linear or quadratic objective functions that have no direct interpretation in terms of dose-volume histogram (DVH) criteria, do not result in an optimum or

Development of inverse-planning system for neutron capture therapy

International Nuclear Information System (INIS)

Kumada, Hiroaki; Yamamoto, Kazuyoshi; Maruo, Takeshi

2006-01-01

To lead proper irradiation condition effectively, Japan Atomic Energy Agency (JAEA) is developing an inverse-planning system for neutron capture therapy (NCT-IPS) based on the JAEA computational dosimetry system (JCDS) for BNCT. The leading methodology of an optimum condition in the NCT-IPS has been applied spatial channel theory with adjoint flux solution of Botzman transport. By analyzing the results obtained from the adjoint flux calculations according to the theory, optimum incident point of the beam against the patient can be found, and neutron spectrum of the beam which can generate ideal distribution of neutron flux around tumor region can be determined. The conceptual design of the NCT-IPS was investigated, and prototype of NCT-IPS with JCDS is being developed. (author)

Study on Real-Time Simulation Analysis and Inverse Analysis System for Temperature and Stress of Concrete Dam

Directory of Open Access Journals (Sweden)

Lei Zhang

2015-01-01

Full Text Available In the concrete dam construction, it is very necessary to strengthen the real-time monitoring and scientific management of concrete temperature control. This paper constructs the analysis and inverse analysis system of temperature stress simulation, which is based on various useful data collected in real time in the process of concrete construction. The system can produce automatically data file of temperature and stress calculation and then achieve the remote real-time simulation calculation of temperature stress by using high performance computing techniques, so the inverse analysis can be carried out based on a basis of monitoring data in the database; it fulfills the automatic feedback calculation according to the error requirement and generates the corresponding curve and chart after the automatic processing and analysis of corresponding results. The system realizes the automation and intellectualization of complex data analysis and preparation work in simulation process and complex data adjustment in the inverse analysis process, which can facilitate the real-time tracking simulation and feedback analysis of concrete temperature stress in construction process and enable you to discover problems timely, take measures timely, and adjust construction scheme and can well instruct you how to ensure project quality.

Advanced Simulation and Computing Business Plan

Energy Technology Data Exchange (ETDEWEB)

Rummel, E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2015-07-09

To maintain a credible nuclear weapons program, the National Nuclear Security Administration’s (NNSA’s) Office of Defense Programs (DP) needs to make certain that the capabilities, tools, and expert staff are in place and are able to deliver validated assessments. This requires a complete and robust simulation environment backed by an experimental program to test ASC Program models. This ASC Business Plan document encapsulates a complex set of elements, each of which is essential to the success of the simulation component of the Nuclear Security Enterprise. The ASC Business Plan addresses the hiring, mentoring, and retaining of programmatic technical staff responsible for building the simulation tools of the nuclear security complex. The ASC Business Plan describes how the ASC Program engages with industry partners—partners upon whom the ASC Program relies on for today’s and tomorrow’s high performance architectures. Each piece in this chain is essential to assure policymakers, who must make decisions based on the results of simulations, that they are receiving all the actionable information they need.

Optimal Inversion Parameters for Full Waveform Inversion using OBS Data Set

Science.gov (United States)

Kim, S.; Chung, W.; Shin, S.; Kim, D.; Lee, D.

2017-12-01

In recent years, full Waveform Inversion (FWI) has been the most researched technique in seismic data processing. It uses the residuals between observed and modeled data as an objective function; thereafter, the final subsurface velocity model is generated through a series of iterations meant to minimize the residuals.Research on FWI has expanded from acoustic media to elastic media. In acoustic media, the subsurface property is defined by P-velocity; however, in elastic media, properties are defined by multiple parameters, such as P-velocity, S-velocity, and density. Further, the elastic media can also be defined by Lamé constants, density or impedance PI, SI; consequently, research is being carried out to ascertain the optimal parameters.From results of advanced exploration equipment and Ocean Bottom Seismic (OBS) survey, it is now possible to obtain multi-component seismic data. However, to perform FWI on these data and generate an accurate subsurface model, it is important to determine optimal inversion parameters among (Vp, Vs, ρ), (λ, μ, ρ), and (PI, SI) in elastic media. In this study, staggered grid finite difference method was applied to simulate OBS survey. As in inversion, l2-norm was set as objective function. Further, the accurate computation of gradient direction was performed using the back-propagation technique and its scaling was done using the Pseudo-hessian matrix.In acoustic media, only Vp is used as the inversion parameter. In contrast, various sets of parameters, such as (Vp, Vs, ρ) and (λ, μ, ρ) can be used to define inversion in elastic media. Therefore, it is important to ascertain the parameter that gives the most accurate result for inversion with OBS data set.In this study, we generated Vp and Vs subsurface models by using (λ, μ, ρ) and (Vp, Vs, ρ) as inversion parameters in every iteration, and compared the final two FWI results.This research was supported by the Basic Research Project(17-3312) of the Korea Institute of

Simulating my own or others action plans?--Motor representations, not visual representations are recalled in motor memory.

Directory of Open Access Journals (Sweden)

Christian Seegelke

Full Text Available Action plans are not generated from scratch for each movement, but features of recently generated plans are recalled for subsequent movements. This study investigated whether the observation of an action is sufficient to trigger plan recall processes. Participant dyads performed an object manipulation task in which one participant transported a plunger from an outer platform to a center platform of different heights (first move. Subsequently, either the same (intra-individual task condition or the other participant (inter-individual task condition returned the plunger to the outer platform (return moves. Grasp heights were inversely related to center target height and similar irrespective of direction (first vs. return move and task condition (intra- vs. inter-individual. Moreover, participants' return move grasp heights were highly correlated with their own, but not with their partners' first move grasp heights. Our findings provide evidence that a simulated action plan resembles a plan of how the observer would execute that action (based on a motor representation rather than a plan of the actually observed action (based on a visual representation.

Inverse planning in the age of digital LINACs: station parameter optimized radiation therapy (SPORT)

Science.gov (United States)

Xing, Lei; Li, Ruijiang

2014-03-01

The last few years have seen a number of technical and clinical advances which give rise to a need for innovations in dose optimization and delivery strategies. Technically, a new generation of digital linac has become available which offers features such as programmable motion between station parameters and high dose-rate Flattening Filter Free (FFF) beams. Current inverse planning methods are designed for traditional machines and cannot accommodate these features of new generation linacs without compromising either dose conformality and/or delivery efficiency. Furthermore, SBRT is becoming increasingly important, which elevates the need for more efficient delivery, improved dose distribution. Here we will give an overview of our recent work in SPORT designed to harness the digital linacs and highlight the essential components of SPORT. We will summarize the pros and cons of traditional beamlet-based optimization (BBO) and direct aperture optimization (DAO) and introduce a new type of algorithm, compressed sensing (CS)-based inverse planning, that is capable of automatically removing the redundant segments during optimization and providing a plan with high deliverability in the presence of a large number of station control points (potentially non-coplanar, non-isocentric, and even multi-isocenters). We show that CS-approach takes the interplay between planning and delivery into account and allows us to balance the dose optimality and delivery efficiency in a controlled way and, providing a viable framework to address various unmet demands of the new generation linacs. A few specific implementation strategies of SPORT in the forms of fixed-gantry and rotational arc delivery are also presented.

Inverse planning in the age of digital LINACs: station parameter optimized radiation therapy (SPORT)

International Nuclear Information System (INIS)

Xing, Lei; Li, Ruijiang

2014-01-01

The last few years have seen a number of technical and clinical advances which give rise to a need for innovations in dose optimization and delivery strategies. Technically, a new generation of digital linac has become available which offers features such as programmable motion between station parameters and high dose-rate Flattening Filter Free (FFF) beams. Current inverse planning methods are designed for traditional machines and cannot accommodate these features of new generation linacs without compromising either dose conformality and/or delivery efficiency. Furthermore, SBRT is becoming increasingly important, which elevates the need for more efficient delivery, improved dose distribution. Here we will give an overview of our recent work in SPORT designed to harness the digital linacs and highlight the essential components of SPORT. We will summarize the pros and cons of traditional beamlet-based optimization (BBO) and direct aperture optimization (DAO) and introduce a new type of algorithm, compressed sensing (CS)-based inverse planning, that is capable of automatically removing the redundant segments during optimization and providing a plan with high deliverability in the presence of a large number of station control points (potentially non-coplanar, non-isocentric, and even multi-isocenters). We show that CS-approach takes the interplay between planning and delivery into account and allows us to balance the dose optimality and delivery efficiency in a controlled way and, providing a viable framework to address various unmet demands of the new generation linacs. A few specific implementation strategies of SPORT in the forms of fixed-gantry and rotational arc delivery are also presented.

SU-E-T-628: A Cloud Computing Based Multi-Objective Optimization Method for Inverse Treatment Planning.

Science.gov (United States)

Na, Y; Suh, T; Xing, L

2012-06-01

Multi-objective (MO) plan optimization entails generation of an enormous number of IMRT or VMAT plans constituting the Pareto surface, which presents a computationally challenging task. The purpose of this work is to overcome the hurdle by developing an efficient MO method using emerging cloud computing platform. As a backbone of cloud computing for optimizing inverse treatment planning, Amazon Elastic Compute Cloud with a master node (17.1 GB memory, 2 virtual cores, 420 GB instance storage, 64-bit platform) is used. The master node is able to scale seamlessly a number of working group instances, called workers, based on the user-defined setting account for MO functions in clinical setting. Each worker solved the objective function with an efficient sparse decomposition method. The workers are automatically terminated if there are finished tasks. The optimized plans are archived to the master node to generate the Pareto solution set. Three clinical cases have been planned using the developed MO IMRT and VMAT planning tools to demonstrate the advantages of the proposed method. The target dose coverage and critical structure sparing of plans are comparable obtained using the cloud computing platform are identical to that obtained using desktop PC (Intel Xeon® CPU 2.33GHz, 8GB memory). It is found that the MO planning speeds up the processing of obtaining the Pareto set substantially for both types of plans. The speedup scales approximately linearly with the number of nodes used for computing. With the use of N nodes, the computational time is reduced by the fitting model, 0.2+2.3/N, with r̂2>0.99, on average of the cases making real-time MO planning possible. A cloud computing infrastructure is developed for MO optimization. The algorithm substantially improves the speed of inverse plan optimization. The platform is valuable for both MO planning and future off- or on-line adaptive re-planning. © 2012 American Association of Physicists in Medicine.

Resampling: An optimization method for inverse planning in robotic radiosurgery

International Nuclear Information System (INIS)

Schweikard, Achim; Schlaefer, Alexander; Adler, John R. Jr.

2006-01-01

By design, the range of beam directions in conventional radiosurgery are constrained to an isocentric array. However, the recent introduction of robotic radiosurgery dramatically increases the flexibility of targeting, and as a consequence, beams need be neither coplanar nor isocentric. Such a nonisocentric design permits a large number of distinct beam directions to be used in one single treatment. These major technical differences provide an opportunity to improve upon the well-established principles for treatment planning used with GammaKnife or LINAC radiosurgery. With this objective in mind, our group has developed over the past decade an inverse planning tool for robotic radiosurgery. This system first computes a set of beam directions, and then during an optimization step, weights each individual beam. Optimization begins with a feasibility query, the answer to which is derived through linear programming. This approach offers the advantage of completeness and avoids local optima. Final beam selection is based on heuristics. In this report we present and evaluate a new strategy for utilizing the advantages of linear programming to improve beam selection. Starting from an initial solution, a heuristically determined set of beams is added to the optimization problem, while beams with zero weight are removed. This process is repeated to sample a set of beams much larger compared with typical optimization. Experimental results indicate that the planning approach efficiently finds acceptable plans and that resampling can further improve its efficiency

Salt-induced effects on natural and inverse DPPC lipid membranes: Molecular dynamics simulation.

Science.gov (United States)

Rezaei Sani, Seyed Mojtaba; Akhavan, Mojdeh; Jalili, Seifollah

2018-08-01

Molecular dynamics (MD) simulations of a dipalmitoylphosphatidylcholine (DPPC) bilayer and its neutral inverse-phosphocholine equivalent (DPCPe) were performed to find salt-induced effects on their surface structure and the nature of ion-lipid interactions. We found that the area per lipid is not considerably affected by the inversion, but the deuterium order parameter of carbon atoms in the region of carbonyl carbons changes dramatically. MD simulations indicate that Ca 2+ ions can bind to the surface of both DPPC and DPCPe membranes, but K + ions do not bind to them. In the case of Na + , however, the ions can bind to natural lipids but not to the inverse ones. Also, our results demonstrate that the hydration level of CPe bilayers is substantially lower than PC bilayers and the averaged orientation of water dipoles in the region of CPe headgroups is effectively inverted compared to PC lipids. This might be important in the interaction of the bilayer with its biological environment. Furthermore, it was found for the CPe bilayers that the enhanced peaks of the electrostatic potential profiles shift further away from the bilayer center relative to those of PC bilayers. This behavior makes the penetration of cations into the bilayer more difficult and possibly explains the experimentally observed enhanced release rates of anionic compounds in the CPe membrane. Copyright © 2018 Elsevier B.V. All rights reserved.

Determination of beam intensity in a single step for IMRT inverse planning

International Nuclear Information System (INIS)

Chuang, Keh-Shih; Chen, Tzong-Jer; Kuo, Shan-Chi; Jan, Meei-Ling; Hwang, Ing-Ming; Chen, Sharon; Lin, Ying-Chuan; Wu, Jay

2003-01-01

In intensity modulated radiotherapy (IMRT), targets are treated by multiple beams at different orientations each with spatially-modulated beam intensities. This approach spreads the normal tissue dose to a greater volume and produces a higher dose conformation to the target. In general, inverse planning is used for IMRT treatment planning. The inverse planning requires iterative calculation of dose distribution in order to optimize the intensity profile for each beam and is very computation intensive. In this paper, we propose a single-step method utilizing a figure of merit (FoM) to estimate the beam intensities for IMRT treatment planning. The FoM of a ray is defined as the ratio between the delivered tumour dose and normal tissue dose and is a good index for the dose efficacy of the ray. To maximize the beam utility, it is natural to irradiate the tumour with intensity of each ray proportional to the value of the FoM. The nonuniform beam intensity profiles are then fixed and the weights of the beam are determined iteratively in order to yield a uniform tumour dose. In this study, beams are employed at equispaced angles around the patient. Each beam with its field size that just covers the tumour is divided into a fixed number of beamlets. The FoM is calculated for each beamlet and this value is assigned to be the beam intensity. Various weighting factors are incorporated in the FoM computation to accommodate different clinical considerations. Two clinical datasets are used to test the feasibility of the algorithm. The resultant dose-volume histograms of this method are presented and compared to that of conformal therapy. Preliminary results indicate that this method reduces the critical organ doses at a small expense of uniformity in tumour dose distribution. This method estimates the beam intensity in one single step and the computation time is extremely fast and can be finished in less than one minute using a regular PC

Capability of leaf interdigitation with different inverse planning strategies in Monaco: an investigation of representative tumour sites

International Nuclear Information System (INIS)

Duan, Jinghao; Meng, Xiangjuan; Liu, Tonghai; Yin, Yong

2016-01-01

The aim of this study was to experimentally assess the dosimetric impact of leaf interdigitation using different inverse treatment strategies for representative tumour sites and to identify the situations in which leaf interdigitation can benefit these tumour sites. Sixty previously treated patients (15 nasopharyngeal carcinoma (NPC), 15 multiple brain metastasis (MBM), 15 cervical cancer and 15 prostate cancer) were re-planned for volumetric modulated arc therapy (VMAT), sliding window IMRT (dMLC) and step-and-shoot IMRT (ssIMRT) with and without leaf interdigitation. Various dosimetric variables, such as PTV coverage, OARs sparing, delivery efficiency and planning time, were evaluated for each plan. In addition, a protocol developed by our group was applied to identify the situations in which leaf interdigitation can achieve benefits in clinical practice. Leaf interdigitation produced few benefits in PTV homogeneity for the MBM VMAT plans and NPC ssIMRT plans. For OARs, sparing was equivalent with and without leaf interdigitation. Leaf interdigitation showed an increase in MUs for dMLC plans and a decrease in MUs for ssIMRT plans. Leaf interdigitation resulted in an increase in segments for dMLC plans and a decrease in segments for NPC and MBM ssIMRT plans. For beam on time, leaf interdigitation showed an increase in MBM dMLC, NPC ssIMRT and prostate ssIMRT plans. In addition, leaf interdigitation saved planning time for VMAT and dMLC plans but increased planning time for ssIMRT plans. Leaf interdigitation does not improve plan quality when performing inverse treatment strategies, regardless of whether the target is simple or complex. However, it influences the delivery efficiency and planning time. Based on these observations, our study suggests that leaf interdigitation should be utilized when performing MBM VMAT plans and NPC ssIMRT plans. The online version of this article (doi:10.1186/s13014-016-0655-1) contains supplementary material, which is available to

Enhancing Student’s Understanding in Entrepreneurship Through Business Plan Simulation

Directory of Open Access Journals (Sweden)

Guzairy M.

2018-01-01

Full Text Available Business Plan is an important document for entrepreneurs to guide them managing their business. Business Plan also assist the entrepreneur to strategies their business and manage future growth. That is why Malaysian government has foster all Higher Education Provider to set entrepreneurship education as compulsory course. One of the entrepreneurship education learning outcome is the student can write effective business plan. This study focused on enhancing student’s understanding in entrepreneurship through business plan simulation. This study also considers which of the factor that most facilitate the business simulation that help the student to prepare effective business plan. The methodology of this study using quantitative approach with pre-and post-research design. 114 students take part as respondent in the business simulation and answer quantitative survey pre-question and post question. The crucial findings of this study are student characteristic factor after playing the simulation contribute much on facilitate business plan learning. The result has shown that the business plan simulation can enhance undergraduate student in understanding entrepreneurship by preparing effective business plan before opening new startup.

Statistical perspectives on inverse problems

DEFF Research Database (Denmark)

Andersen, Kim Emil

of the interior of an object from electrical boundary measurements. One part of this thesis concerns statistical approaches for solving, possibly non-linear, inverse problems. Thus inverse problems are recasted in a form suitable for statistical inference. In particular, a Bayesian approach for regularisation...... problem is given in terms of probability distributions. Posterior inference is obtained by Markov chain Monte Carlo methods and new, powerful simulation techniques based on e.g. coupled Markov chains and simulated tempering is developed to improve the computational efficiency of the overall simulation......Inverse problems arise in many scientific disciplines and pertain to situations where inference is to be made about a particular phenomenon from indirect measurements. A typical example, arising in diffusion tomography, is the inverse boundary value problem for non-invasive reconstruction...

Comparative behaviour of the Dynamically Penalized Likelihood algorithm in inverse radiation therapy planning

Energy Technology Data Exchange (ETDEWEB)

Llacer, Jorge [EC Engineering Consultants, LLC, Los Gatos, CA (United States)]. E-mail: jllacer@home.com; Solberg, Timothy D. [Department of Radiation Oncology, University of California, Los Angeles, CA (United States)]. E-mail: Solberg@radonc.ucla.edu; Promberger, Claus [BrainLAB AG, Heimstetten (Germany)]. E-mail: promberg@brainlab.com

2001-10-01

This paper presents a description of tests carried out to compare the behaviour of five algorithms in inverse radiation therapy planning: (1) The Dynamically Penalized Likelihood (DPL), an algorithm based on statistical estimation theory; (2) an accelerated version of the same algorithm; (3) a new fast adaptive simulated annealing (ASA) algorithm; (4) a conjugate gradient method; and (5) a Newton gradient method. A three-dimensional mathematical phantom and two clinical cases have been studied in detail. The phantom consisted of a U-shaped tumour with a partially enclosed 'spinal cord'. The clinical examples were a cavernous sinus meningioma and a prostate case. The algorithms have been tested in carefully selected and controlled conditions so as to ensure fairness in the assessment of results. It has been found that all five methods can yield relatively similar optimizations, except when a very demanding optimization is carried out. For the easier cases, the differences are principally in robustness, ease of use and optimization speed. In the more demanding case, there are significant differences in the resulting dose distributions. The accelerated DPL emerges as possibly the algorithm of choice for clinical practice. An appendix describes the differences in behaviour between the new ASA method and the one based on a patent by the Nomos Corporation. (author)

Anatomy-based inverse planning dose optimization in HDR prostate implant: A toxicity study

International Nuclear Information System (INIS)

Mahmoudieh, Alireza; Tremblay, Christine; Beaulieu, Luc; Lachance, Bernard; Harel, Francois; Lessard, Etienne; Pouliot, Jean; Vigneault, Eric

2005-01-01

Background and purpose: The aim of this study is to evaluate the acute and late complications in patients who have received HDR implant boost using inverse planning, and to determine dose volume correlations. Patients and methods: Between September 1999 and October 2002, 44 patients with locally advanced prostate cancer (PSA ≥10 ng/ml, and/or Gleason score ≥7, and/or Stage T2c or higher) were treated with 40-45 Gy external pelvic field followed by 2-3 fraction of inverse-planned HDR implant boost (6-9.5 Gy /fraction). Median follow-up time was 1.7 years with 81.8% of patients who had at least 12 months of follow up (range 8.6-42.5. Acute and late morbidity data were collected and graded according to RTOG criteria. Questionnaires were used to collect prostate related measures of quality of life, and international prostate symptom score (IPSS) before and after treatment. Dose-volume histograms for prostate, urethra, bladder, penis bulb and rectum were analyzed. Results: The median patient age was 64 years. Of these, 32% were in the high risk group, and 61% in the intermediate risk group. 3 patients (7%) had no adverse prognostic factors. A single grade 3 GU acute toxicity was reported but no grade 3-4 acute GI toxicity. No grade 3-4 late GU or GI toxicity was reported. Acute (late) grade 2 urinary and rectal symptoms were reported in 31.8 (11.4%) and 4.6% (4.6%) of patients, respectively. A trend for predicting acute GU toxicity is seen for total HDR dose of more than 18 Gy (OR=3.6, 95%CI=[0.96-13.5], P=0.058). The evolution of toxicity is presented for acute and late GU/GI toxicity. Erectile dysfunction occurs in approximately 27% of patients who were not on hormonal deprivation, but may be taking sildenafil. The IPSS peaked on averaged 6 weeks post-implant and returned to the baseline at a median of 6 months. Conclusions: Inverse-planned HDR brachytherapy is a viable option to deliver higher dose to the prostate as a boost without increasing GU or rectal

Adaptive Core Simulation Employing Discrete Inverse Theory - Part I: Theory

International Nuclear Information System (INIS)

Abdel-Khalik, Hany S.; Turinsky, Paul J.

2005-01-01

Use of adaptive simulation is intended to improve the fidelity and robustness of important core attribute predictions such as core power distribution, thermal margins, and core reactivity. Adaptive simulation utilizes a selected set of past and current reactor measurements of reactor observables, i.e., in-core instrumentation readings, to adapt the simulation in a meaningful way. A meaningful adaption will result in high-fidelity and robust adapted core simulator models. To perform adaption, we propose an inverse theory approach in which the multitudes of input data to core simulators, i.e., reactor physics and thermal-hydraulic data, are to be adjusted to improve agreement with measured observables while keeping core simulator models unadapted. At first glance, devising such adaption for typical core simulators with millions of input and observables data would spawn not only several prohibitive challenges but also numerous disparaging concerns. The challenges include the computational burdens of the sensitivity-type calculations required to construct Jacobian operators for the core simulator models. Also, the computational burdens of the uncertainty-type calculations required to estimate the uncertainty information of core simulator input data present a demanding challenge. The concerns however are mainly related to the reliability of the adjusted input data. The methodologies of adaptive simulation are well established in the literature of data adjustment. We adopt the same general framework for data adjustment; however, we refrain from solving the fundamental adjustment equations in a conventional manner. We demonstrate the use of our so-called Efficient Subspace Methods (ESMs) to overcome the computational and storage burdens associated with the core adaption problem. We illustrate the successful use of ESM-based adaptive techniques for a typical boiling water reactor core simulator adaption problem

Forward versus inverse planning in oropharyngeal cancer: A comparative study using physical and biological indices

Directory of Open Access Journals (Sweden)

T Sundaram

2013-01-01

Full Text Available Context: Possible benefits of inverse planning. Aims: To analyze possible benefits of inverse planning intensity modulated radiation therapy (IMRT over field-in-field 3D conformal radiation therapy (FIF-3DCRT and to evaluate the differences if any, between low (6 Million Volts and high energy (15 Million Volts IMRT plans. Materials and Methods: Ten patients with squamous cell carcinoma of oropharynx, previously treated with 6 MV step and shoot IMRT were studied. V 100 , V 33 , V 66 , mean dose and normal tissue complication probabilities (NTCP were evaluated for parotid glands. Maximum dose and NTCP were the parameters for spinal cord. Statistical Analysis Used: A two-tailed t-test was applied to analyze statistical significance between the different techniques. Results: For combined parotid gland, a reduction of 4.374 Gy, 9.343 Gy and 7.883 Gy were achieved for D 100 , D 66 and D 33 , respectively in 6 MV-IMRT when compared with FIF-3DCRT. Spinal cord sparing was better in 6 MV-IMRT (40.963 ± 2.650, with an average reduction of maximum spinal cord dose by 7.355 Gy from that using the FIF-3DCRT technique. The uncomplicated tumor control probabilities values were higher in IMRT plans thus leading to a possibility of dose escalation. Conclusions: Though low-energy IMRT is the preferred choice for treatment of oropharyngeal cancers, FIF-3DCRT must be given due consideration as a second choice for its well established advantages over traditional conventioan technique.

System Planning With The Hanford Waste Operations Simulator

International Nuclear Information System (INIS)

Crawford, T.W.; Certa, P.J.; Wells, M.N.

2010-01-01

At the U. S. Department of Energy's Hanford Site in southeastern Washington State, 216 million liters (57 million gallons) of nuclear waste is currently stored in aging underground tanks, threatening the Columbia River. The River Protection Project (RPP), a fully integrated system of waste storage, retrieval, treatment, and disposal facilities, is in varying stages of design, construction, operation, and future planning. These facilities face many overlapping technical, regulatory, and financial hurdles to achieve site cleanup and closure. Program execution is ongoing, but completion is currently expected to take approximately 40 more years. Strategic planning for the treatment of Hanford tank waste is by nature a multi-faceted, complex and iterative process. To help manage the planning, a report referred to as the RPP System Plan is prepared to provide a basis for aligning the program scope with the cost and schedule, from upper-tier contracts to individual facility operating plans. The Hanford Tank Waste Operations Simulator (HTWOS), a dynamic flowsheet simulation and mass balance computer model, is used to simulate the current planned RPP mission, evaluate the impacts of changes to the mission, and assist in planning near-term facility operations. Development of additional modeling tools, including an operations research model and a cost model, will further improve long-term planning confidence. The most recent RPP System Plan, Revision 4, was published in September 2009.

Adaptive Core Simulation Employing Discrete Inverse Theory - Part II: Numerical Experiments

International Nuclear Information System (INIS)

Abdel-Khalik, Hany S.; Turinsky, Paul J.

2005-01-01

Use of adaptive simulation is intended to improve the fidelity and robustness of important core attribute predictions such as core power distribution, thermal margins, and core reactivity. Adaptive simulation utilizes a selected set of past and current reactor measurements of reactor observables, i.e., in-core instrumentation readings, to adapt the simulation in a meaningful way. The companion paper, ''Adaptive Core Simulation Employing Discrete Inverse Theory - Part I: Theory,'' describes in detail the theoretical background of the proposed adaptive techniques. This paper, Part II, demonstrates several computational experiments conducted to assess the fidelity and robustness of the proposed techniques. The intent is to check the ability of the adapted core simulator model to predict future core observables that are not included in the adaption or core observables that are recorded at core conditions that differ from those at which adaption is completed. Also, this paper demonstrates successful utilization of an efficient sensitivity analysis approach to calculate the sensitivity information required to perform the adaption for millions of input core parameters. Finally, this paper illustrates a useful application for adaptive simulation - reducing the inconsistencies between two different core simulator code systems, where the multitudes of input data to one code are adjusted to enhance the agreement between both codes for important core attributes, i.e., core reactivity and power distribution. Also demonstrated is the robustness of such an application

Inverse planning of energy-modulated electron beams in radiotherapy

International Nuclear Information System (INIS)

Gentry, John R.; Steeves, Richard; Paliwal, Bhudatt A.

2006-01-01

The use of megavoltage electron beams often poses a clinical challenge in that the planning target volume (PTV) is anterior to other radiosensitive structures and has variable depth. To ensure that skin as well as the deepest extent of the PTV receives the prescribed dose entails prescribing to a point beyond the depth of peak dose for a single electron energy. This causes dose inhomogeneities and heightened potential for tissue fibrosis, scarring, and possible soft tissue necrosis. Use of bolus on the skin improves the entrant dose at the cost of decreasing the therapeutic depth that can be treated. Selection of a higher energy to improve dose homogeneity results in increased dose to structures beyond the PTV, as well as enlargement of the volume receiving heightened dose. Measured electron data from a linear accelerator was used as input to create an inverse planning tool employing energy and intensity modulation using bolus (e-IMRT TM ). Using tools readily available in a radiotherapy department, the applications of energy and intensity modulation on the central axis makes it possible to remove hot spots of 115% or more over the depths clinically encountered. The e-IMRT TM algorithm enables the development of patient-specific dose distributions with user-defined positions of peak dose, range, and reduced dose to points beyond the prescription point

An Interactive Simulation Tool for Production Planning in Bacon Factories

DEFF Research Database (Denmark)

Nielsen, Jens Frederik Dalsgaard; Nielsen, Kirsten Mølgaard

1994-01-01

The paper describes an interactive simulation tool for production planning in bacon factories. The main aim of the tool is to make it possible to combine the production plans of all parts of the factory......The paper describes an interactive simulation tool for production planning in bacon factories. The main aim of the tool is to make it possible to combine the production plans of all parts of the factory...

Dosimetric and QA aspects of Konrad inverse planning system for commissioning intensity-modulated radiation therapy

Directory of Open Access Journals (Sweden)

Deshpande Shrikant

2007-01-01

Full Text Available The intensity-modulated radiation therapy (IMRT planning is performed using the Konrad inverse treatment planning system and the delivery of the treatment by using Siemens Oncor Impression Plus linear accelerator (step and shoot, which has been commissioned recently. The basic beam data required for commissioning the system were generate. The quality assurance of relative and absolute dose distribution was carried out before clinical implementation. The salient features of Konrad planning system, like dependence of grid size on dose volume histogram (DVH, number of intensity levels and step size in sequencer, are studied quantitatively and qualitatively. To verify whether the planned dose [from treatment planning system (TPS] and delivered dose are the same, the absolute dose at a point is determined using CC01 ion chamber and the axial plane dose distribution is carried out using Kodak EDR2 in conjunction with OmniPro IMRT Phantom and OmniPro IMRT software from Scanditronix Wellhofer. To obtain the optimum combination in leaf sequencer module, parameters like number of intensity levels, step size are analyzed. The difference between pixel values of optimum fluence profile and the fluence profile obtained for various combinations of number of intensity levels and step size is compared and plotted. The calculations of the volume of any RT structure in the dose volume histogram are compared using grid sizes 3 mm and 4 mm. The measured and planned dose at a point showed good agreement (< 3% except for a few cases wherein the chamber was placed in a relatively high dose gradient region. The axial plane dose distribution using film dosimetry shows excellent agreement (correlation coefficient> 0.97 in all the cases. In the leaf sequencer module, the combination of number of intensity level 7 with step size of 3 is the optimal solution for obtaining deliverable segments. The RT structure volume calculation is found to be more accurate with grid size of

A Treatment Planning Analysis of Inverse-Planned and Forward-Planned Intensity-Modulated Radiation Therapy in Nasopharyngeal Carcinoma

International Nuclear Information System (INIS)

Poon, Ian M; Xia Ping; Weinberg, Vivien; Sultanem, Khalil; Akazawa, Clayton C.; Akazawa, Pamela C.; Verhey, Lynn; Quivey, Jeanne Marie; Lee, Nancy

2007-01-01

Purpose: To compare dose-volume histograms of target volumes and organs at risk in 57 patients with nasopharyngeal carcinoma (NPC) with inverse- (IP) or forward-planned (FP) intensity-modulated radiation treatment (IMRT). Methods and Materials: The DVHs of 57 patients with NPC with IMRT with or without chemotherapy were reviewed. Thirty-one patients underwent IP IMRT, and 26 patients underwent FP IMRT. Treatment goals were to prescribe a minimum dose of 66-70 Gy for gross tumor volume and 59.4 Gy for planning target volume to greater than 95% of the volume. Multiple selected end points were used to compare dose-volume histograms of the targets, including minimum, mean, and maximum doses; percentage of target volume receiving less than 90% (1-V90%), less than 95% (1-V95%), and greater than 105% (1-V105%). Dose-volume histograms of organs at risk were evaluated with characteristic end points. Results: Both planning methods provided excellent target coverage with no statistically significant differences found, although a trend was suggested in favor of improved target coverage with IP IMRT in patients with T3/T4 NPC (p = 0.10). Overall, IP IMRT statistically decreased the dose to the parotid gland, temporomandibular joint, brain stem, and spinal cord overall, whereas IP led to a dose decrease to the middle/inner ear in only the T1/T2 subgroup. Conclusions: Use of IP and FP IMRT can lead to good target coverage while maintaining critical structures within tolerance. The IP IMRT selectively spared these critical organs to a greater degree and should be considered the standard of treatment in patients with NPC, particularly those with T3/T4. The FP IMRT is an effective second option in centers with limited IP IMRT capacity. As a modification of conformal techniques, the human/departmental resources to incorporate FP-IMRT should be nominal

Convection methodology for fission track annealing: direct and inverse numerical simulations in the multi-exponential case

International Nuclear Information System (INIS)

Miellou, J.C.; Igli, H.; Grivet, M.; Rebetez, M.; Chambaudet, A.

1994-01-01

In minerals, the uranium fission tracks are sensitive to temperature and time. The consequence is that the etchable lengths are reduced. To simulate the phenomenon, at the last International Conference on Nuclear Tracks in solids at Beijing in 1992, we proposed a convection model for fission track annealing based on a reaction situation associated with only one activation energy. Moreover a simple inverse method based on the resolution of an ordinary differential equation was described, making it possible to retrace the thermal history in this mono-exponential situation. The aim of this paper is to consider a more involved class of models including multi-exponentials associated with several activation energies. We shall describe in this framework the modelling of the direct phenomenon and the resolution of the inverse problem. Results of numerical simulations and comparison with the mono-exponential case will be presented. 5 refs. (author)

Acute small bowel toxicity and preoperative chemoradiotherapy for rectal cancer: Investigating dose-volume relationships and role for inverse planning

International Nuclear Information System (INIS)

Tho, Lye Mun; Glegg, Martin; Paterson, Jennifer; Yap, Christina; MacLeod, Alice; McCabe, Marie; McDonald, Alexander C.

2006-01-01

Purpose: The relationship between volume of irradiated small bowel (VSB) and acute toxicity in rectal cancer radiotherapy is poorly quantified, particularly in patients receiving concurrent preoperative chemoradiotherapy. Using treatment planning data, we studied a series of such patients. Methods and Materials: Details of 41 patients with locally advanced rectal cancer were reviewed. All received 45 Gy in 25 fractions over 5 weeks, 3-4 fields three-dimensional conformal radiotherapy with daily 5-fluorouracil and folinic acid during Weeks 1 and 5. Toxicity was assessed prospectively in a weekly clinic. Using computed tomography planning software, the VSB was determined at 5 Gy dose intervals (V 5 , V 1 , etc.). Eight patients with maximal VSB had dosimetry and radiobiological modeling outcomes compared between inverse and conformal three-dimensional planning. Results: VSB correlated strongly with diarrheal severity at every dose level (p 5 and V 15 . Conclusions: A strong dose-volume relationship exists between VSB and acute diarrhea at all dose levels during preoperative chemoradiotherapy. Our constructed model may be useful in predicting toxicity, and this has been derived without the confounding influence of surgical excision on bowel function. Inverse planning can reduce calculated dose to small bowel and late NTCP, and its clinical role warrants further investigation

The dosimetric impact of inversely optimized arc radiotherapy plan modulation for real-time dynamic MLC tracking delivery

International Nuclear Information System (INIS)

Falk, Marianne; Larsson, Tobias; Keall, Paul; Chul Cho, Byung; Aznar, Marianne; Korreman, Stine; Poulsen, Per; Munck af Rosenschoeld, Per

2012-01-01

Purpose: Real-time dynamic multileaf collimator (MLC) tracking for management of intrafraction tumor motion can be challenging for highly modulated beams, as the leaves need to travel far to adjust for target motion perpendicular to the leaf travel direction. The plan modulation can be reduced by using a leaf position constraint (LPC) that reduces the difference in the position of adjacent MLC leaves in the plan. The purpose of this study was to investigate the impact of the LPC on the quality of inversely optimized arc radiotherapy plans and the effect of the MLC motion pattern on the dosimetric accuracy of MLC tracking delivery. Specifically, the possibility of predicting the accuracy of MLC tracking delivery based on the plan modulation was investigated. Methods: Inversely optimized arc radiotherapy plans were created on CT-data of three lung cancer patients. For each case, five plans with a single 358 deg. arc were generated with LPC priorities of 0 (no LPC), 0.25, 0.5, 0.75, and 1 (highest possible LPC), respectively. All the plans had a prescribed dose of 2 Gy x 30, used 6 MV, a maximum dose rate of 600 MU/min and a collimator angle of 45 deg. or 315 deg. To quantify the plan modulation, an average adjacent leaf distance (ALD) was calculated by averaging the mean adjacent leaf distance for each control point. The linear relationship between the plan quality [i.e., the calculated dose distributions and the number of monitor units (MU)] and the LPC was investigated, and the linear regression coefficient as well as a two tailed confidence level of 95% was used in the evaluation. The effect of the plan modulation on the performance of MLC tracking was tested by delivering the plans to a cylindrical diode array phantom moving with sinusoidal motion in the superior-inferior direction with a peak-to-peak displacement of 2 cm and a cycle time of 6 s. The delivery was adjusted to the target motion using MLC tracking, guided in real-time by an infrared optical system

ANALYTICAL AND SIMULATION PLANNING MODEL OF URBAN PASSENGER TRANSPORT

Directory of Open Access Journals (Sweden)

Andrey Borisovich Nikolaev

2017-09-01

Full Text Available The article described the structure of the analytical and simulation models to make informed decisions in the planning of urban passenger transport. Designed UML diagram that describes the relationship of classes of the proposed model. A description of the main agents of the model developed in the simulation AnyLogic. Designed user interface integration with GIS map. Also provides simulation results that allow concluding about her health and the possibility of its use in solving planning problems of urban passenger transport.

A Graphical Interactive Simulation Environment for Production Planning in Bacon Factories

DEFF Research Database (Denmark)

Nielsen, Kirsten Mølgaard; Nielsen, Jens Frederik Dalsgaard

1994-01-01

The paper describes a graphical interactive simulation tool for production planning in bacon factories........The paper describes a graphical interactive simulation tool for production planning in bacon factories.....

Comparison of CT-based 3D treatment planning with simulator planning of pelvic irradiation of primary cervical carcinoma

International Nuclear Information System (INIS)

Knocke, T.H.; Pokrajac, B.; Fellner, C.; Poetter, R.

1999-01-01

In a prospective study on 20 subsequent patients with primary cervical carcinoma in Stages I to III simulator planning of a 4-field box-technique was performed. After defining the planning target volume (PTV) in the 3D planning system the field configuration of the simulator planning was transmitted. The resulting plan was compared to a second one based on the defined PTV and evaluated regarding a possible geographical miss and encompassment of the PTV by the treated volume (ICRU). Volumes of open and shaped portals were calculated for both techniques. Planning by simulation resulted in 1 geographical miss and in 10 more cases the encompassment of the PTV by the treated volume was inadequate. For a PTV of mean 1 729 cm 3 the mean volume defined by simulation was 3 120 cm 3 for the open portals and 2 702 cm 3 for the shaped portals. The volume reduction by blocks was 13,4% (mean). With CT-based 3D treatment planning the volume of the open portals was 3,3% (mean) enlarged to 3 224 cm 3 . The resulting mean volume of the shaped portals was 2 458 ccm. The reduction compared to the open portals was 23,8% (mean). The treated volumes were 244 cm 3 or 9% (mean) smaller compared to simulator planning. The 'treated volume/planning target volume ratio' was decreased from 1.59 to 1.42. (orig.) [de

SU-E-T-14: A Comparative Study Between Forward and Inverse Planning in Gamma Knife Radiosurgery for Acoustic Neuroma Tumours

Energy Technology Data Exchange (ETDEWEB)

Gopishankar, N; Agarwal, Priyanka; Bisht, Raj Kishor; Kale, S S; Rath, G K; Chander, S; Sharma, B S [All India Institute of Medical Sciences, New Delhi (India)

2015-06-15

Purpose: To evaluate forward and inverse planning methods for acoustic neuroma cases treated in Gamma Knife Perfexion. Methods: Five patients with acoustic neuroma tumour abutting brainstem were planned twice in LGP TPS (Version 10.1) using TMR10 algorithm. First plan was entirely based on forward planning (FP) in which each shot was chosen manually. Second plan was generated using inverse planning (IP) for which planning parameters like coverage, selectivity, gradient index (GI) and beam-on time threshold were set. Number of shots in IP was automatically selected by objective function using iterative process. In both planning methods MRI MPRAGE sequence images were used for tumour localization and planning. A planning dose of 12Gy at 50% isodose level was chosen. Results and Discussion: Number of shots used in FP was greater than IP and beam-on time in FP was in average 1.4 times more than IP. One advantage of FP was that the brainstem volume subjected to 6Gy dose (25% isodose) was less in FP than IP. Our results showed use of more number of shots as in FP results in GI less than or equal to 2.55 which is close to its lower limit. Dose homogeneity index (DHI) analysis of FP and IP showed average values of 0.59 and 0.67 respectively. General trend in GK for planning in acoustic neuroma cases is to use small collimator shots to avoid dose to adjacent critical structures. More number of shots and prolonged treatment time causes inconvenience to the patients. Similarly overuse of automatic shot shaping as in IP results in increased scatter dose. A compromise is required in shot selection for these cases. Conclusion: IP method could be used in acoustic neuroma cases to decrease treatment time provided the source sector openings near brainstem are shielded or adjusted appropriately to reduce brainstem dose.

Simulation of inverse Compton scattering and its implications on the scattered linewidth

Science.gov (United States)

Ranjan, N.; Terzić, B.; Krafft, G. A.; Petrillo, V.; Drebot, I.; Serafini, L.

2018-03-01

Rising interest in inverse Compton sources has increased the need for efficient models that properly quantify the behavior of scattered radiation given a set of interaction parameters. The current state-of-the-art simulations rely on Monte Carlo-based methods, which, while properly expressing scattering behavior in high-probability regions of the produced spectra, may not correctly simulate such behavior in low-probability regions (e.g. tails of spectra). Moreover, sampling may take an inordinate amount of time for the desired accuracy to be achieved. In this paper, we present an analytic derivation of the expression describing the scattered radiation linewidth and propose a model to describe the effects of horizontal and vertical emittance on the properties of the scattered radiation. We also present an improved version of the code initially reported in Krafft et al. [Phys. Rev. Accel. Beams 19, 121302 (2016), 10.1103/PhysRevAccelBeams.19.121302], that can perform the same simulations as those present in cain and give accurate results in low-probability regions by integrating over the emissions of the electrons. Finally, we use these codes to carry out simulations that closely verify the behavior predicted by the analytically derived scaling law.

Prototyping and validating requirements of radiation and nuclear emergency plan simulator

Energy Technology Data Exchange (ETDEWEB)

Hamid, AHA., E-mail: amyhamijah@nm.gov.my [Malaysian Nuclear Agency (NM), Bangi, 43000 Kajang, Selangor (Malaysia); Faculty of Computing, Universiti Teknologi Malaysia (UTM), Skudai, 81310 Johor Bahru, Johor (Malaysia); Rozan, MZA.; Ibrahim, R.; Deris, S.; Selamat, A. [Faculty of Computing, Universiti Teknologi Malaysia (UTM), Skudai, 81310 Johor Bahru, Johor (Malaysia)

2015-04-29

Organizational incapability in developing unrealistic, impractical, inadequate and ambiguous mechanisms of radiological and nuclear emergency preparedness and response plan (EPR) causing emergency plan disorder and severe disasters. These situations resulting from 65.6% of poor definition and unidentified roles and duties of the disaster coordinator. Those unexpected conditions brought huge aftermath to the first responders, operators, workers, patients and community at large. Hence, in this report, we discuss prototyping and validating of Malaysia radiation and nuclear emergency preparedness and response plan simulation model (EPRM). A prototyping technique was required to formalize the simulation model requirements. Prototyping as systems requirements validation was carried on to endorse the correctness of the model itself against the stakeholder’s intensions in resolving those organizational incapability. We have made assumptions for the proposed emergency preparedness and response model (EPRM) through the simulation software. Those assumptions provided a twofold of expected mechanisms, planning and handling of the respective emergency plan as well as in bringing off the hazard involved. This model called RANEPF (Radiation and Nuclear Emergency Planning Framework) simulator demonstrated the training emergency response perquisites rather than the intervention principles alone. The demonstrations involved the determination of the casualties’ absorbed dose range screening and the coordination of the capacity planning of the expected trauma triage. Through user-centred design and sociotechnical approach, RANEPF simulator was strategized and simplified, though certainly it is equally complex.

Prototyping and validating requirements of radiation and nuclear emergency plan simulator

Science.gov (United States)

Hamid, AHA.; Rozan, MZA.; Ibrahim, R.; Deris, S.; Selamat, A.

2015-04-01

Organizational incapability in developing unrealistic, impractical, inadequate and ambiguous mechanisms of radiological and nuclear emergency preparedness and response plan (EPR) causing emergency plan disorder and severe disasters. These situations resulting from 65.6% of poor definition and unidentified roles and duties of the disaster coordinator. Those unexpected conditions brought huge aftermath to the first responders, operators, workers, patients and community at large. Hence, in this report, we discuss prototyping and validating of Malaysia radiation and nuclear emergency preparedness and response plan simulation model (EPRM). A prototyping technique was required to formalize the simulation model requirements. Prototyping as systems requirements validation was carried on to endorse the correctness of the model itself against the stakeholder's intensions in resolving those organizational incapability. We have made assumptions for the proposed emergency preparedness and response model (EPRM) through the simulation software. Those assumptions provided a twofold of expected mechanisms, planning and handling of the respective emergency plan as well as in bringing off the hazard involved. This model called RANEPF (Radiation and Nuclear Emergency Planning Framework) simulator demonstrated the training emergency response perquisites rather than the intervention principles alone. The demonstrations involved the determination of the casualties' absorbed dose range screening and the coordination of the capacity planning of the expected trauma triage. Through user-centred design and sociotechnical approach, RANEPF simulator was strategized and simplified, though certainly it is equally complex.

Prototyping and validating requirements of radiation and nuclear emergency plan simulator

International Nuclear Information System (INIS)

Hamid, AHA.; Rozan, MZA.; Ibrahim, R.; Deris, S.; Selamat, A.

2015-01-01

Organizational incapability in developing unrealistic, impractical, inadequate and ambiguous mechanisms of radiological and nuclear emergency preparedness and response plan (EPR) causing emergency plan disorder and severe disasters. These situations resulting from 65.6% of poor definition and unidentified roles and duties of the disaster coordinator. Those unexpected conditions brought huge aftermath to the first responders, operators, workers, patients and community at large. Hence, in this report, we discuss prototyping and validating of Malaysia radiation and nuclear emergency preparedness and response plan simulation model (EPRM). A prototyping technique was required to formalize the simulation model requirements. Prototyping as systems requirements validation was carried on to endorse the correctness of the model itself against the stakeholder’s intensions in resolving those organizational incapability. We have made assumptions for the proposed emergency preparedness and response model (EPRM) through the simulation software. Those assumptions provided a twofold of expected mechanisms, planning and handling of the respective emergency plan as well as in bringing off the hazard involved. This model called RANEPF (Radiation and Nuclear Emergency Planning Framework) simulator demonstrated the training emergency response perquisites rather than the intervention principles alone. The demonstrations involved the determination of the casualties’ absorbed dose range screening and the coordination of the capacity planning of the expected trauma triage. Through user-centred design and sociotechnical approach, RANEPF simulator was strategized and simplified, though certainly it is equally complex

Estimation of Dynamic Friction Process of the Akatani Landslide Based on the Waveform Inversion and Numerical Simulation

Science.gov (United States)

Yamada, M.; Mangeney, A.; Moretti, L.; Matsushi, Y.

2014-12-01

Understanding physical parameters, such as frictional coefficients, velocity change, and dynamic history, is important issue for assessing and managing the risks posed by deep-seated catastrophic landslides. Previously, landslide motion has been inferred qualitatively from topographic changes caused by the event, and occasionally from eyewitness reports. However, these conventional approaches are unable to evaluate source processes and dynamic parameters. In this study, we use broadband seismic recordings to trace the dynamic process of the deep-seated Akatani landslide that occurred on the Kii Peninsula, Japan, which is one of the best recorded large slope failures. Based on the previous results of waveform inversions and precise topographic surveys done before and after the event, we applied numerical simulations using the SHALTOP numerical model (Mangeney et al., 2007). This model describes homogeneous continuous granular flows on a 3D topography based on a depth averaged thin layer approximation. We assume a Coulomb's friction law with a constant friction coefficient, i. e. the friction is independent of the sliding velocity. We varied the friction coefficients in the simulation so that the resulting force acting on the surface agrees with the single force estimated from the seismic waveform inversion. Figure shows the force history of the east-west components after the band-pass filtering between 10-100 seconds. The force history of the simulation with frictional coefficient 0.27 (thin red line) the best agrees with the result of seismic waveform inversion (thick gray line). Although the amplitude is slightly different, phases are coherent for the main three pulses. This is an evidence that the point-source approximation works reasonably well for this particular event. The friction coefficient during the sliding was estimated to be 0.38 based on the seismic waveform inversion performed by the previous study and on the sliding block model (Yamada et al., 2013

pyGIMLi: An open-source library for modelling and inversion in geophysics

Science.gov (United States)

Rücker, Carsten; Günther, Thomas; Wagner, Florian M.

2017-12-01

Many tasks in applied geosciences cannot be solved by single measurements, but require the integration of geophysical, geotechnical and hydrological methods. Numerical simulation techniques are essential both for planning and interpretation, as well as for the process understanding of modern geophysical methods. These trends encourage open, simple, and modern software architectures aiming at a uniform interface for interdisciplinary and flexible modelling and inversion approaches. We present pyGIMLi (Python Library for Inversion and Modelling in Geophysics), an open-source framework that provides tools for modelling and inversion of various geophysical but also hydrological methods. The modelling component supplies discretization management and the numerical basis for finite-element and finite-volume solvers in 1D, 2D and 3D on arbitrarily structured meshes. The generalized inversion framework solves the minimization problem with a Gauss-Newton algorithm for any physical forward operator and provides opportunities for uncertainty and resolution analyses. More general requirements, such as flexible regularization strategies, time-lapse processing and different sorts of coupling individual methods are provided independently of the actual methods used. The usage of pyGIMLi is first demonstrated by solving the steady-state heat equation, followed by a demonstration of more complex capabilities for the combination of different geophysical data sets. A fully coupled hydrogeophysical inversion of electrical resistivity tomography (ERT) data of a simulated tracer experiment is presented that allows to directly reconstruct the underlying hydraulic conductivity distribution of the aquifer. Another example demonstrates the improvement of jointly inverting ERT and ultrasonic data with respect to saturation by a new approach that incorporates petrophysical relations in the inversion. Potential applications of the presented framework are manifold and include time

Simulation based planning of surgical interventions in pediatric cardiology

Science.gov (United States)

Marsden, Alison L.

2013-10-01

Hemodynamics plays an essential role in the progression and treatment of cardiovascular disease. However, while medical imaging provides increasingly detailed anatomical information, clinicians often have limited access to hemodynamic data that may be crucial to patient risk assessment and treatment planning. Computational simulations can now provide detailed hemodynamic data to augment clinical knowledge in both adult and pediatric applications. There is a particular need for simulation tools in pediatric cardiology, due to the wide variation in anatomy and physiology in congenital heart disease patients, necessitating individualized treatment plans. Despite great strides in medical imaging, enabling extraction of flow information from magnetic resonance and ultrasound imaging, simulations offer predictive capabilities that imaging alone cannot provide. Patient specific simulations can be used for in silico testing of new surgical designs, treatment planning, device testing, and patient risk stratification. Furthermore, simulations can be performed at no direct risk to the patient. In this paper, we outline the current state of the art in methods for cardiovascular blood flow simulation and virtual surgery. We then step through pressing challenges in the field, including multiscale modeling, boundary condition selection, optimization, and uncertainty quantification. Finally, we summarize simulation results of two representative examples from pediatric cardiology: single ventricle physiology, and coronary aneurysms caused by Kawasaki disease. These examples illustrate the potential impact of computational modeling tools in the clinical setting.

Fast Simulation of 3-D Surface Flanging and Prediction of the Flanging Lines Based On One-Step Inverse Forming Algorithm

International Nuclear Information System (INIS)

Bao Yidong; Hu Sibo; Lang Zhikui; Hu Ping

2005-01-01

A fast simulation scheme for 3D curved binder flanging and blank shape prediction of sheet metal based on one-step inverse finite element method is proposed, in which the total plasticity theory and proportional loading assumption are used. The scheme can be actually used to simulate 3D flanging with complex curve binder shape, and suitable for simulating any type of flanging model by numerically determining the flanging height and flanging lines. Compared with other methods such as analytic algorithm and blank sheet-cut return method, the prominent advantage of the present scheme is that it can directly predict the location of the 3D flanging lines when simulating the flanging process. Therefore, the prediction time of flanging lines will be obviously decreased. Two typical 3D curve binder flanging including stretch and shrink characters are simulated in the same time by using the present scheme and incremental FE non-inverse algorithm based on incremental plasticity theory, which show the validity and high efficiency of the present scheme

A fast inverse treatment planning strategy facilitating optimized catheter selection in image-guided high-dose-rate interstitial gynecologic brachytherapy.

Science.gov (United States)

Guthier, Christian V; Damato, Antonio L; Hesser, Juergen W; Viswanathan, Akila N; Cormack, Robert A

2017-12-01

Interstitial high-dose rate (HDR) brachytherapy is an important therapeutic strategy for the treatment of locally advanced gynecologic (GYN) cancers. The outcome of this therapy is determined by the quality of dose distribution achieved. This paper focuses on a novel yet simple heuristic for catheter selection for GYN HDR brachytherapy and their comparison against state of the art optimization strategies. The proposed technique is intended to act as a decision-supporting tool to select a favorable needle configuration. The presented heuristic for catheter optimization is based on a shrinkage-type algorithm (SACO). It is compared against state of the art planning in a retrospective study of 20 patients who previously received image-guided interstitial HDR brachytherapy using a Syed Neblett template. From those plans, template orientation and position are estimated via a rigid registration of the template with the actual catheter trajectories. All potential straight trajectories intersecting the contoured clinical target volume (CTV) are considered for catheter optimization. Retrospectively generated plans and clinical plans are compared with respect to dosimetric performance and optimization time. All plans were generated with one single run of the optimizer lasting 0.6-97.4 s. Compared to manual optimization, SACO yields a statistically significant (P ≤ 0.05) improved target coverage while at the same time fulfilling all dosimetric constraints for organs at risk (OARs). Comparing inverse planning strategies, dosimetric evaluation for SACO and "hybrid inverse planning and optimization" (HIPO), as gold standard, shows no statistically significant difference (P > 0.05). However, SACO provides the potential to reduce the number of used catheters without compromising plan quality. The proposed heuristic for needle selection provides fast catheter selection with optimization times suited for intraoperative treatment planning. Compared to manual optimization, the

Empowering stakeholders through simulation in water resources planning

International Nuclear Information System (INIS)

Palmer, R.N.; Keyes, A.M.; Fisher, S.

1993-01-01

During the past two years, researchers at the University of Washington (UW) have had the unique opportunity to facilitate and observe the development of drought planning activities associated with the National Drought Study (NDS) and its Drought Preparedness Studies (DPS) sites as sponsored by the Institute of Water Resources of the US Army Corps of Engineers. Each of the DPS sites is unique, with different study objectives and institutional constraints. However, one uniform requirement of the study is to develop tactical and strategic drought plans that can be successfully implemented within the study region. At the onset of the study, it was recognized that successful implementation is directly related to the active involvement of affected parties and agencies (denoted as stakeholders) and the degree to which they support the plan's conclusions. Their involvement is also necessary because the problems addressed by the DPS's require the experience and knowledge of a variety of water resource interests in order to arrive at effective alternatives. Their support of the plan conclusions enables regional implementation. Several techniques were used to encourage stakeholder participation in the planning process. Individuals representing the stakeholders had a wide range of professional backgrounds. This paper concentrates on one specific approach found useful in encouraging comprehensive and meaningful participation by a wide range of stakeholders; the development of object-oriented simulation models for the water resource systems under study. Simulation models were to develop tactical and strategic drought plans and to ensure the acceptance of the plans by building consensus among the stakeholders. The remainder of this paper describes: how simulation models became a part of the National Drought Study, procedures used to develop the DPS models, and how the model empowered stakeholders

Simulation-based decision support for evaluating operational plans

Directory of Open Access Journals (Sweden)

Johan Schubert

2015-12-01

Full Text Available In this article, we describe simulation-based decision support techniques for evaluation of operational plans within effects-based planning. Using a decision support tool, developers of operational plans are able to evaluate thousands of alternative plans against possible courses of events and decide which of these plans are capable of achieving a desired end state. The objective of this study is to examine the potential of a decision support system that helps operational analysts understand the consequences of numerous alternative plans through simulation and evaluation. Operational plans are described in the effects-based approach to operations concept as a set of actions and effects. For each action, we examine several different alternative ways to perform the action. We use a representation where a plan consists of several actions that should be performed. Each action may be performed in one of several different alternative ways. Together these action alternatives make up all possible plan instances, which are represented as a tree of action alternatives that may be searched for the most effective sequence of alternative actions. As a test case, we use an expeditionary operation with a plan of 43 actions and several alternatives for these actions, as well as a scenario of 40 group actors. Decision support for planners is provided by several methods that analyze the impact of a plan on the 40 actors, e.g., by visualizing time series of plan performance. Detailed decision support for finding the most influential actions of a plan is presented by using sensitivity analysis and regression tree analysis. Finally, a decision maker may use the tool to determine the boundaries of an operation that it must not move beyond without risk of drastic failure. The significant contribution of this study is the presentation of an integrated approach for evaluation of operational plans.

Objective mapping of observed sub-surface mesoscale cold core eddy in the Bay of Bengal by stochastic inverse technique with tomographically simulated travel times

Digital Repository Service at National Institute of Oceanography (India)

Murty, T.V.R.; Rao, M.M.M.; Sadhuram, Y.; Sridevi, B.; Maneesha, K.; SujithKumar, S.; Prasanna, P.L.; Murthy, K.S.R.

of Bengal during south-west monsoon season and explore possibility to reconstruct the acoustic profile of the eddy by Stochastic Inverse Technique. A simulation experiment on forward and inverse problems for observed sound velocity perturbation field has...

a Simulation-As Framework Facilitating Webgis Based Installation Planning

Science.gov (United States)

Zheng, Z.; Chang, Z. Y.; Fei, Y. F.

2017-09-01

Installation Planning is constrained by both natural and social conditions, especially for spatially sparse but functionally connected facilities. Simulation is important for proper deploy in space and configuration in function of facilities to make them a cohesive and supportive system to meet users' operation needs. Based on requirement analysis, we propose a framework to combine GIS and Agent simulation to overcome the shortness in temporal analysis and task simulation of traditional GIS. In this framework, Agent based simulation runs as a service on the server, exposes basic simulation functions, such as scenario configuration, simulation control, and simulation data retrieval to installation planners. At the same time, the simulation service is able to utilize various kinds of geoprocessing services in Agents' process logic to make sophisticated spatial inferences and analysis. This simulation-as-a-service framework has many potential benefits, such as easy-to-use, on-demand, shared understanding, and boosted performances. At the end, we present a preliminary implement of this concept using ArcGIS javascript api 4.0 and ArcGIS for server, showing how trip planning and driving can be carried out by agents.

Development of a residency program in radiation oncology physics: an inverse planning approach.

Science.gov (United States)

Khan, Rao F H; Dunscombe, Peter B

2016-03-08

Over the last two decades, there has been a concerted effort in North America to organize medical physicists' clinical training programs along more structured and formal lines. This effort has been prompted by the Commission on Accreditation of Medical Physics Education Programs (CAMPEP) which has now accredited about 90 residency programs. Initially the accreditation focused on standardized and higher quality clinical physics training; the development of rounded professionals who can function at a high level in a multidisciplinary environment was recognized as a priority of a radiation oncology physics residency only lately. In this report, we identify and discuss the implementation of, and the essential components of, a radiation oncology physics residency designed to produce knowledgeable and effective clinical physicists for today's safety-conscious and collaborative work environment. Our approach is that of inverse planning, by now familiar to all radiation oncology physicists, in which objectives and constraints are identified prior to the design of the program. Our inverse planning objectives not only include those associated with traditional residencies (i.e., clinical physics knowledge and critical clinical skills), but also encompass those other attributes essential for success in a modern radiation therapy clinic. These attributes include formal training in management skills and leadership, teaching and communication skills, and knowledge of error management techniques and patient safety. The constraints in our optimization exercise are associated with the limited duration of a residency and the training resources available. Without compromising the knowledge and skills needed for clinical tasks, we have successfully applied the model to the University of Calgary's two-year residency program. The program requires 3840 hours of overall commitment from the trainee, of which 7%-10% is spent in obtaining formal training in nontechnical "soft skills".

Theory and simulation of an inverse free-electron laser experiment

Science.gov (United States)

Gou, S. K.; Bhattacharjee, A.; Fang, J.-M.; Marshall, T. C.

1997-03-01

An experimental demonstration of the acceleration of electrons using a high-power CO2 laser interacting with a relativistic electron beam moving along a wiggler has been carried out at the Accelerator Test Facility of the Brookhaven National Laboratory [Phys. Rev. Lett. 77, 2690 (1996)]. The data generated by this inverse free-electron-laser (IFEL) experiment are studied by means of theory and simulation. Included in the simulations are such effects as: a low-loss metallic waveguide with a dielectric coating on the walls; multi-mode coupling due to self-consistent interaction between the electrons and the optical wave; space charge; energy spread of the electrons; and arbitrary wiggler-field profile. Two types of wiggler profile are considered: a linear taper of the period, and a step-taper of the period. (The period of the wiggler is ˜3 cm, its magnetic field is ˜1 T, and the wiggler length is 0.47 m.) The energy increment of the electrons (˜1-2%) is analyzed in detail as a function of laser power, wiggler parameters, and the initial beam energy (˜40 MeV). At a laser power level ˜0.5 Gw, the simulation results on energy gain are in reasonable agreement with the experimental results. Preliminary results on the electron energy distribution at the end of the IFEL are presented. Whereas the experiment produces a near-monotone distribution of electron energies with the peak shifted to higher energy, the simulation shows a more structured and non-monotonic distribution at the end of the wiggler. Effects that may help reconcile these differences are considered.

Solving the patient zero inverse problem by using generalized simulated annealing

Science.gov (United States)

Menin, Olavo H.; Bauch, Chris T.

2018-01-01

Identifying patient zero - the initially infected source of a given outbreak - is an important step in epidemiological investigations of both existing and emerging infectious diseases. Here, the use of the Generalized Simulated Annealing algorithm (GSA) to solve the inverse problem of finding the source of an outbreak is studied. The classical disease natural histories susceptible-infected (SI), susceptible-infected-susceptible (SIS), susceptible-infected-recovered (SIR) and susceptible-infected-recovered-susceptible (SIRS) in a regular lattice are addressed. Both the position of patient zero and its time of infection are considered unknown. The algorithm performance with respect to the generalization parameter q˜v and the fraction ρ of infected nodes for whom infection was ascertained is assessed. Numerical experiments show the algorithm is able to retrieve the epidemic source with good accuracy, even when ρ is small, but present no evidence to support that GSA performs better than its classical version. Our results suggest that simulated annealing could be a helpful tool for identifying patient zero in an outbreak where not all cases can be ascertained.

Simulation by the method of inverse cumulative distribution function applied in optimising of foundry plant production

Directory of Open Access Journals (Sweden)

J. Szymszal

2009-01-01

Full Text Available The study discusses application of computer simulation based on the method of inverse cumulative distribution function. The simulationrefers to an elementary static case, which can also be solved by physical experiment, consisting mainly in observations of foundryproduction in a selected foundry plant. For the simulation and forecasting of foundry production quality in selected cast iron grade, arandom number generator of Excel calculation sheet was chosen. Very wide potentials of this type of simulation when applied to theevaluation of foundry production quality were demonstrated, using a number generator of even distribution for generation of a variable ofan arbitrary distribution, especially of a preset empirical distribution, without any need of adjusting to this variable the smooth theoreticaldistributions.

Planning organization and productivity simulation tool for maritime container terminals

Directory of Open Access Journals (Sweden)

B. Beškovnik

2010-09-01

Full Text Available The article describes a proposed planning organization and productivity simulation tool, with a special emphasis on orientations to the optimization of operations in a maritime container terminal. With the application of an adequate model frame for traffic and technical-technologic forecasting, infrastructure and manpower planning and productivity simulation are possible to measure and increase the productivity in the whole subsystem of the maritime container terminal. The emphasis is mainly put on setting up planning organization in order to collect important information and consequently to raise productivity. This is the main task and goal of terminal management that must develop elements and strategies for optimal operational and financial production. An adequate planning structure must use simplified but efficient simulation tools enabling owners and management to take a vast number of adequate financial and operational decisions. Considering all important and very dynamic facts in container and shipping industry, the proposed simulation tool gives a helpful instrument for checking productivity and its time variation and monitoring a competitive position of a certain maritime terminal with the terminals from the same group. Therefore, the management of every maritime container terminal must establish an appropriate internal planning system as a mechanism for strategic decision support relating basically to the assessment of the best development and optimization solutions for the infrastructure and suprastructure of the entire system.

IPIP: A new approach to inverse planning for HDR brachytherapy by directly optimizing dosimetric indices

International Nuclear Information System (INIS)

Siauw, Timmy; Cunha, Adam; Atamtuerk, Alper; Hsu, I-Chow; Pouliot, Jean; Goldberg, Ken

2011-01-01

Purpose: Many planning methods for high dose rate (HDR) brachytherapy require an iterative approach. A set of computational parameters are hypothesized that will give a dose plan that meets dosimetric criteria. A dose plan is computed using these parameters, and if any dosimetric criteria are not met, the process is iterated until a suitable dose plan is found. In this way, the dose distribution is controlled by abstract parameters. The purpose of this study is to develop a new approach for HDR brachytherapy by directly optimizing the dose distribution based on dosimetric criteria. Methods: The authors developed inverse planning by integer program (IPIP), an optimization model for computing HDR brachytherapy dose plans and a fast heuristic for it. They used their heuristic to compute dose plans for 20 anonymized prostate cancer image data sets from patients previously treated at their clinic database. Dosimetry was evaluated and compared to dosimetric criteria. Results: Dose plans computed from IPIP satisfied all given dosimetric criteria for the target and healthy tissue after a single iteration. The average target coverage was 95%. The average computation time for IPIP was 30.1 s on an Intel(R) Core TM 2 Duo CPU 1.67 GHz processor with 3 Gib RAM. Conclusions: IPIP is an HDR brachytherapy planning system that directly incorporates dosimetric criteria. The authors have demonstrated that IPIP has clinically acceptable performance for the prostate cases and dosimetric criteria used in this study, in both dosimetry and runtime. Further study is required to determine if IPIP performs well for a more general group of patients and dosimetric criteria, including other cancer sites such as GYN.

Comparison of step and shoot IMRT treatment plans generated by three inverse treatment planning systems; Comparacion de tratamientos de IMRT estatica generados por tres sistemas de planificacion inversa

Energy Technology Data Exchange (ETDEWEB)

Perez Moreno, J. M.; Zucca Aparicio, D.; Fernandez leton, P.; Garcia Ruiz-Zorrilla, J.; Minambres Moro, A.

2011-07-01

One of the most important issues of intensity modulated radiation therapy (IMRT) treatments using the step-and-shoot technique is the number of segments and monitor units (MU) for treatment delivery. These parameters depend heavily on the inverse optimization module of the treatment planning system (TPS) used. Three commercial treatment planning systems: CMS XiO, iPlan and Prowess Panther have been evaluated. With each of them we have generated a treatment plan for the same group of patients, corresponding to clinical cases. Dosimetric results, MU calculated and number of segments were compared. Prowess treatment planning system generates plans with a number of segments significantly lower than other systems, while MU are less than a half. It implies important reductions in leakage radiation and delivery time. Degradation in the final dose calculation of dose is very small, because it directly optimizes positions of multileaf collimator (MLC). (Author) 13 refs.

Adaptive Planning: Understanding Organizational Workload to Capability/ Capacity through Modeling and Simulation

Science.gov (United States)

Hase, Chris

2010-01-01

In August 2003, the Secretary of Defense (SECDEF) established the Adaptive Planning (AP) initiative [1] with an objective of reducing the time necessary to develop and revise Combatant Commander (COCOM) contingency plans and increase SECDEF plan visibility. In addition to reducing the traditional plan development timeline from twenty-four months to less than twelve months (with a goal of six months)[2], AP increased plan visibility to Department of Defense (DoD) leadership through In-Progress Reviews (IPRs). The IPR process, as well as the increased number of campaign and contingency plans COCOMs had to develop, increased the workload while the number of planners remained fixed. Several efforts from collaborative planning tools to streamlined processes were initiated to compensate for the increased workload enabling COCOMS to better meet shorter planning timelines. This paper examines the Joint Strategic Capabilities Plan (JSCP) directed contingency planning and staffing requirements assigned to a combatant commander staff through the lens of modeling and simulation. The dynamics of developing a COCOM plan are captured with an ExtendSim [3] simulation. The resulting analysis provides a quantifiable means by which to measure a combatant commander staffs workload associated with development and staffing JSCP [4] directed contingency plans with COCOM capability/capacity. Modeling and simulation bring significant opportunities in measuring the sensitivity of key variables in the assessment of workload to capability/capacity analysis. Gaining an understanding of the relationship between plan complexity, number of plans, planning processes, and number of planners with time required for plan development provides valuable information to DoD leadership. Through modeling and simulation AP leadership can gain greater insight in making key decisions on knowing where to best allocate scarce resources in an effort to meet DoD planning objectives.

Inverse Flush Air Data System (FADS) for Real Time Simulations

Science.gov (United States)

Madhavanpillai, Jayakumar; Dhoaya, Jayanta; Balakrishnan, Vidya Saraswathi; Narayanan, Remesh; Chacko, Finitha Kallely; Narayanan, Shyam Mohan

2017-12-01

Flush Air Data Sensing System (FADS) forms a mission critical sub system in future reentry vehicles. FADS makes use of surface pressure measurements from the nose cap of the vehicle for deriving the air data parameters of the vehicle such as angle of attack, angle of sideslip, Mach number, etc. These parameters find use in the flight control and guidance systems, and also assist in the overall mission management. The FADS under consideration in this paper makes use of nine pressure ports located in the nose cap of a technology demonstrator vehicle. In flight, the air data parameters are obtained from the FADS estimation algorithm using the pressure data at the nine pressure ports. But, these pressure data will not be available, for testing the FADS package during ground simulation. So, an inverse software to FADS which estimates the pressure data at the pressure ports for a given flight condition is developed. These pressure data at the nine ports will go as input to the FADS package during ground simulation. The software is run to generate the pressure data for the descent phase trajectory of the technology demonstrator. This data is used again to generate the air data parameters from FADS algorithm. The computed results from FADS algorithm match well with the trajectory data.

Theory and Simulation of an Inverse Free Electron Laser Experiment

Science.gov (United States)

Guo, S. K.; Bhattacharjee, A.; Fang, J. M.; Marshall, T. C.

1996-11-01

An experimental demonstration of the acceleration of electrons using a high power CO2 laser in an inverse free electron laser (IFEL) is underway at the Brookhaven National Laboratory. This experiment has generated data, which we are attempting to simulate. Included in our studies are such effects as: a low-loss metallic waveguide with a dielectric coating on the walls; multi-mode coupling due to self-consistent interaction between the electrons and the optical wave; space charge (which is significant at lower laser power); energy-spread of the electrons; arbitrary wiggler field profile; and slippage. Two types of wiggler profile have been considered: a linear taper of the period, and a step-taper of the period (the period is ~ 3cm, the field is ~ 1T, and the wiggler length is 47cm). The energy increment of the electrons ( ~ 1-2%) is analyzed in detail as a function of laser power, wiggler parameters, and the initial beam energy (40MeV). For laser power ~ 0.5GW, the predictions of the simulations are in good accord with experimental results. A matter currently under study is the discrepancy between theory and observations for the electron energy distribution observed at the end of the IFEL. This work is supported by the Department of Energy.

Analysis of RAE-1 inversion

Science.gov (United States)

Hedland, D. A.; Degonia, P. K.

1974-01-01

The RAE-1 spacecraft inversion performed October 31, 1972 is described based upon the in-orbit dynamical data in conjunction with results obtained from previously developed computer simulation models. The computer simulations used are predictive of the satellite dynamics, including boom flexing, and are applicable during boom deployment and retraction, inter-phase coast periods, and post-deployment operations. Attitude data, as well as boom tip data, were analyzed in order to obtain a detailed description of the dynamical behavior of the spacecraft during and after the inversion. Runs were made using the computer model and the results were analyzed and compared with the real time data. Close agreement between the actual recorded spacecraft attitude and the computer simulation results was obtained.

Multidimensional inversion

International Nuclear Information System (INIS)

Desesquelles, P.

1997-01-01

Computer Monte Carlo simulations occupy an increasingly important place between theory and experiment. This paper introduces a global protocol for the comparison of model simulations with experimental results. The correlated distributions of the model parameters are determined using an original recursive inversion procedure. Multivariate analysis techniques are used in order to optimally synthesize the experimental information with a minimum number of variables. This protocol is relevant in all fields if physics dealing with event generators and multi-parametric experiments. (authors)

Internet-based system for simulation-based medical planning for cardiovascular disease.

Science.gov (United States)

Steele, Brooke N; Draney, Mary T; Ku, Joy P; Taylor, Charles A

2003-06-01

Current practice in vascular surgery utilizes only diagnostic and empirical data to plan treatments, which does not enable quantitative a priori prediction of the outcomes of interventions. We have previously described simulation-based medical planning methods to model blood flow in arteries and plan medical treatments based on physiologic models. An important consideration for the design of these patient-specific modeling systems is the accessibility to physicians with modest computational resources. We describe a simulation-based medical planning environment developed for the World Wide Web (WWW) using the Virtual Reality Modeling Language (VRML) and the Java programming language.

Inverse Kinematic Analysis and Evaluation of a Robot for Nondestructive Testing Application

Directory of Open Access Journals (Sweden)

Zongxing Lu

2015-01-01

Full Text Available The robot system has been utilized in the nondestructive testing field in recent years. However, only a few studies have focused on the application of ultrasonic testing for complex work pieces with the robot system. The inverse kinematics problem of the 6-DOF robot should be resolved before the ultrasonic testing task. A new effective solution for curved-surface scanning with a 6-DOF robot system is proposed in this study. A new arm-wrist separateness method is adopted to solve the inverse problem of the robot system. Eight solutions of the joint angles can be acquired with the proposed inverse kinematics method. The shortest distance rule is adopted to optimize the inverse kinematics solutions. The best joint-angle solution is identified. Furthermore, a 3D-application software is developed to simulate ultrasonic trajectory planning for complex-shape work pieces with a 6-DOF robot. Finally, the validity of the scanning method is verified based on the C-scan results of a work piece with a curved surface. The developed robot ultrasonic testing system is validated. The proposed method provides an effective solution to this problem and would greatly benefit the development of industrial nondestructive testing.

Conceptual formulation on four-dimensional inverse planning for intensity modulated radiation therapy

International Nuclear Information System (INIS)

Lee, Louis; Ma Yunzhi; Xing Lei; Ye Yinyu

2009-01-01

Four-dimensional computed tomography (4DCT) offers an extra dimension of 'time' on the three-dimensional patient model with which we can incorporate target motion in radiation treatment (RT) planning and delivery in various ways such as in the concept of internal target volume, in gated treatment or in target tracking. However, for all these methodologies, different phases are essentially considered as non-interconnected independent phases for the purpose of optimization, in other words, the 'time' dimension has yet to be incorporated explicitly in the optimization algorithm and fully exploited. In this note, we have formulated a new 4D inverse planning technique that treats all the phases in the 4DCT as one single entity in the optimization. The optimization is formulated as a quadratic problem for disciplined convex programming that enables the problem to be analyzed and solved efficiently. In the proof-of-principle examples illustrated, we show that the temporal information of the spatial relation of the target and organs at risk could be 'exchanged' amongst different phases so that an appropriate weighting of dose deposition could be allocated to each phase, thus enabling a treatment with a tight target margin and a full duty cycle otherwise not achievable by either of the aforementioned methodologies. Yet there are practical issues to be solved in the 4D RT planning and delivery. The 4D concept in the optimization we have formulated here does provide insight on how the 'time' dimension can be exploited in the 4D optimization process. (note)

A High-Speed Train Operation Plan Inspection Simulation Model

Directory of Open Access Journals (Sweden)

Yang Rui

2018-01-01

Full Text Available We developed a train operation simulation tool to inspect a train operation plan. In applying an improved Petri Net, the train was regarded as a token, and the line and station were regarded as places, respectively, in accordance with the high-speed train operation characteristics and network function. Location change and running information transfer of the high-speed train were realized by customizing a variety of transitions. The model was built based on the concept of component combination, considering the random disturbance in the process of train running. The simulation framework can be generated quickly and the system operation can be completed according to the different test requirements and the required network data. We tested the simulation tool when used for the real-world Wuhan to Guangzhou high-speed line. The results showed that the proposed model can be developed, the simulation results basically coincide with the objective reality, and it can not only test the feasibility of the high-speed train operation plan, but also be used as a support model to develop the simulation platform with more capabilities.

Surgical robot setup simulation with consistent kinematics and haptics for abdominal surgery.

Science.gov (United States)

Hayashibe, Mitsuhiro; Suzuki, Naoki; Hattori, Asaki; Suzuki, Shigeyuki; Konishi, Kozo; Kakeji, Yoshihiro; Hashizume, Makoto

2005-01-01

Preoperative simulation and planning of surgical robot setup should accompany advanced robotic surgery if their advantages are to be further pursued. Feedback from the planning system will plays an essential role in computer-aided robotic surgery in addition to preoperative detailed geometric information from patient CT/MRI images. Surgical robot setup simulation systems for appropriate trocar site placement have been developed especially for abdominal surgery. The motion of the surgical robot can be simulated and rehearsed with kinematic constraints at the trocar site, and the inverse-kinematics of the robot. Results from simulation using clinical patient data verify the effectiveness of the proposed system.

The dose-volume constraint satisfaction problem for inverse treatment planning with field segments

International Nuclear Information System (INIS)

Michalski, Darek; Xiao, Ying; Censor, Yair; Galvin, James M

2004-01-01

The prescribed goals of radiation treatment planning are often expressed in terms of dose-volume constraints. We present a novel formulation of a dose-volume constraint satisfaction search for the discretized radiation therapy model. This approach does not rely on any explicit cost function. Inverse treatment planning uses the aperture-based approach with predefined, according to geometric rules, segmental fields. The solver utilizes the simultaneous version of the cyclic subgradient projection algorithm. This is a deterministic iterative method designed for solving the convex feasibility problems. A prescription is expressed with the set of inequalities imposed on the dose at the voxel resolution. Additional constraint functions control the compliance with selected points of the expected cumulative dose-volume histograms. The performance of this method is tested on prostate and head-and-neck cases. The relationships with other models and algorithms of similar conceptual origin are discussed. The demonstrated advantages of the method are: the equivalence of the algorithmic and prescription parameters, the intuitive setup of free parameters, and the improved speed of the method as compared to similar iterative as well as other techniques. The technique reported here will deliver approximate solutions for inconsistent prescriptions

Plan Validation Using DES and Agent-based Simulation

National Research Council Canada - National Science Library

Wong, Teck H; Ong, Kim S

2008-01-01

.... This thesis explores the possibility of using a multi-agent system (MAS) to generate the aggressor's air strike plans, which could be coupled with a low resolution Discrete Event Simulation (DES...

On the Structure and Adjustment of Inversion-Capped Neutral Atmospheric Boundary-Layer Flows: Large-Eddy Simulation Study

DEFF Research Database (Denmark)

Pedersen, Jesper Grønnegaard; Gryning, Sven-Erik; Kelly, Mark C.

2014-01-01

A range of large-eddy simulations, with differing free atmosphere stratification and zero or slightly positive surface heat flux, is investigated to improve understanding of the neutral and near-neutral, inversion-capped, horizontally homogeneous, barotropic atmospheric boundary layer with emphasis...... on the upper region. We find that an adjustment time of at least 16 h is needed for the simulated flow to reach a quasi-steady state. The boundary layer continues to grow, but at a slow rate that changes little after 8 h of simulation time. A common feature of the neutral simulations is the development...... of a super-geostrophic jet near the top of the boundary layer. The analytical wind-shear models included do not account for such a jet, and the best agreement with simulated wind shear is seen in cases with weak stratification above the boundary layer. Increasing the surface heat flux decreases the magnitude...

The use of discrete-event simulation modelling to improve radiation therapy planning processes.

Science.gov (United States)

Werker, Greg; Sauré, Antoine; French, John; Shechter, Steven

2009-07-01

The planning portion of the radiation therapy treatment process at the British Columbia Cancer Agency is efficient but nevertheless contains room for improvement. The purpose of this study is to show how a discrete-event simulation (DES) model can be used to represent this complex process and to suggest improvements that may reduce the planning time and ultimately reduce overall waiting times. A simulation model of the radiation therapy (RT) planning process was constructed using the Arena simulation software, representing the complexities of the system. Several types of inputs feed into the model; these inputs come from historical data, a staff survey, and interviews with planners. The simulation model was validated against historical data and then used to test various scenarios to identify and quantify potential improvements to the RT planning process. Simulation modelling is an attractive tool for describing complex systems, and can be used to identify improvements to the processes involved. It is possible to use this technique in the area of radiation therapy planning with the intent of reducing process times and subsequent delays for patient treatment. In this particular system, reducing the variability and length of oncologist-related delays contributes most to improving the planning time.

Simulation-based planning for theater air warfare

Science.gov (United States)

Popken, Douglas A.; Cox, Louis A., Jr.

2004-08-01

Planning for Theatre Air Warfare can be represented as a hierarchy of decisions. At the top level, surviving airframes must be assigned to roles (e.g., Air Defense, Counter Air, Close Air Support, and AAF Suppression) in each time period in response to changing enemy air defense capabilities, remaining targets, and roles of opposing aircraft. At the middle level, aircraft are allocated to specific targets to support their assigned roles. At the lowest level, routing and engagement decisions are made for individual missions. The decisions at each level form a set of time-sequenced Courses of Action taken by opposing forces. This paper introduces a set of simulation-based optimization heuristics operating within this planning hierarchy to optimize allocations of aircraft. The algorithms estimate distributions for stochastic outcomes of the pairs of Red/Blue decisions. Rather than using traditional stochastic dynamic programming to determine optimal strategies, we use an innovative combination of heuristics, simulation-optimization, and mathematical programming. Blue decisions are guided by a stochastic hill-climbing search algorithm while Red decisions are found by optimizing over a continuous representation of the decision space. Stochastic outcomes are then provided by fast, Lanchester-type attrition simulations. This paper summarizes preliminary results from top and middle level models.

Two-dimensional probabilistic inversion of plane-wave electromagnetic data: Methodology, model constraints and joint inversion with electrical resistivity data

NARCIS (Netherlands)

Rosas-Carbajal, M.; Linde, N.; Kalscheuer, T.; Vrugt, J.A.

2014-01-01

Probabilistic inversion methods based on Markov chain Monte Carlo (MCMC) simulation are well suited to quantify parameter and model uncertainty of nonlinear inverse problems. Yet, application of such methods to CPU-intensive forward models can be a daunting task, particularly if the parameter space

Seismic signal simulation and study of underground nuclear sources by moment inversion

International Nuclear Information System (INIS)

Crusem, R.

1986-09-01

Some problems of underground nuclear explosions are examined from the seismological point of view. In the first part a model is developed for mean seismic propagation through the lagoon of Mururoa atoll and for calculation of synthetic seismograms (in intermediate fields: 5 to 20 km) by summation of discrete wave numbers. In the second part this ground model is used with a linear inversion method of seismic moments for estimation of elastic source terms equivalent to the nuclear source. Only the isotrope part is investigated solution stability is increased by using spectral smoothing and a minimal phase hypothesis. Some examples of applications are presented: total energy estimation of a nuclear explosion, simulation of mechanical effects induced by an underground explosion [fr

Quantization effects on the inversion mode of a double gate MOS

Science.gov (United States)

Mondol, Kalyan; Hasan, Md. Manzurul; Arafath, Yeasir; Alam, Khairul

We investigate the quantization effects on the gate capacitance and charge distribution of a double gate MOSFET using a self-consistent solution of Poisson and Schrödinger equations of the industry standard simulation package Silvaco. Quantization effects on the gate C-V are simulated by varying the electron and hole effective masses. We notice that the inversion capacitance value decreases as the effective mass goes below 0.1mo and the shape of the C-V curve changes to step like in the inversion. We also notice that the inversion switches from surface inversion to volume inversion for low effective mass, and the quantization effect (step like shape) in C-V and volume inversion in charge profile happen at the same effective mass.

Inverse Interval Matrix: A Survey

Czech Academy of Sciences Publication Activity Database

Rohn, Jiří; Farhadsefat, R.

2011-01-01

Roč. 22, - (2011), s. 704-719 E-ISSN 1081-3810 R&D Projects: GA ČR GA201/09/1957; GA ČR GC201/08/J020 Institutional research plan: CEZ:AV0Z10300504 Keywords : interval matrix * inverse interval matrix * NP-hardness * enclosure * unit midpoint * inverse sign stability * nonnegative invertibility * absolute value equation * algorithm Subject RIV: BA - General Mathematics Impact factor: 0.808, year: 2010 http://www.math.technion.ac.il/iic/ ela / ela -articles/articles/vol22_pp704-719.pdf

Quantization effects on the inversion mode of a double gate MOS

Directory of Open Access Journals (Sweden)

Kalyan Mondol

Full Text Available We investigate the quantization effects on the gate capacitance and charge distribution of a double gate MOSFET using a self-consistent solution of Poisson and Schrödinger equations of the industry standard simulation package Silvaco. Quantization effects on the gate C–V are simulated by varying the electron and hole effective masses. We notice that the inversion capacitance value decreases as the effective mass goes below 0.1mo and the shape of the C–V curve changes to step like in the inversion. We also notice that the inversion switches from surface inversion to volume inversion for low effective mass, and the quantization effect (step like shape in C–V and volume inversion in charge profile happen at the same effective mass. Keywords: Double gate MOSFETs, Quantum effects, Energy quantization, Channel inversion, Charge density

Basic considerations in simulated treatment planning for the Stanford Medical Pion Generator (SMPG)

International Nuclear Information System (INIS)

Pistenma, D.A.; Li, G.C.; Bagshaw, M.A.

1977-01-01

Recent interest in charged heavy particle irradiation is based upon expected improved local tumor control rates because of the greater precision in dose localization and the increased biological effectiveness of the high linear energy transfer ionization of particle beams in their stopping regions (Bragg peaks). A novel 60 beam cylindrical geometry pion spectrometer designed for a hospital-based pion therapy facility has been constructed at Stanford. In conjunction with the development and testing of the SMPG a program of simulated treatment planning is being conducted. This paper presents basic considerations in treatment planning for pions and other charged heavy particles. It also presents the status of simulated treatment planning calculations for the SMPG including a discussion of the principle of irradiation of hypothetical tumor volumes illustrated by examples of simplified treatment plans incorporating tissue density inhomogeneity corrections. Also presented are considerations for realistic simulated treatment planning calculations using computerized tomographic scan cross sections of actual patients and a conceptual plan for an integrated treatment planning and patient treatment system for the SMPG

Forward modeling. Route to electromagnetic inversion

Energy Technology Data Exchange (ETDEWEB)

Groom, R; Walker, P [PetRos EiKon Incorporated, Ontario (Canada)

1996-05-01

Inversion of electromagnetic data is a topical subject in the literature, and much time has been devoted to understanding the convergence properties of various inverse methods. The relative lack of success of electromagnetic inversion techniques is partly attributable to the difficulties in the kernel forward modeling software. These difficulties come in two broad classes: (1) Completeness and robustness, and (2) convergence, execution time and model simplicity. If such problems exist in the forward modeling kernel, it was demonstrated that inversion can fail to generate reasonable results. It was suggested that classical inversion techniques, which are based on minimizing a norm of the error between data and the simulated data, will only be successful when these difficulties in forward modeling kernels are properly dealt with. 4 refs., 5 figs.

Lean Supply Chain Planning: A Performance Evaluation through Simulation

Directory of Open Access Journals (Sweden)

Rossini Matteo

2016-01-01

Full Text Available Nowadays companies look more and more for improving their efficiency to excel in the market. At the same time, the competition has moved from firm level to whole supply chain level. Supply chain are very complex systems and lacks of coordination among their members leads to inefficiency. Supply chain planning task is to improve coordination among supply chain members. Which is the best planning solution to improve efficiency is an open issue. On the other hand, Lean approach is becoming more and more popular among managers. Lean approach is recognize as efficiency engine for production systems, but effects of Lean implementation out of single firm boundaries is not clear. This paper aims at providing a theoretical and practical starting point for Lean implementation in supply chain planning issue. To reach it, a DES simulation model of a three-echelon and multi-product supply chain has been set. Lean management is a very broad topic and this paper focuses on two principles of “pull” and “create the flow”. Kanban system and setup-time and batch-size reductions are implemented in the lean-configured supply chain to apply “pull” and “create the flow” respectively. Lean principles implementations have been analyzed and compared with other supply chain planning policies: EOQ and information sharing (Visibility. Supported by the simulation study, this paper points Lean supply chain planning is a competitive planning policies to increase efficiency.

A SIMULATION-AS-A-SERVICE FRAMEWORK FACILITATING WEBGIS BASED INSTALLATION PLANNING

Directory of Open Access Journals (Sweden)

Z. Zheng

2017-09-01

Full Text Available Installation Planning is constrained by both natural and social conditions, especially for spatially sparse but functionally connected facilities. Simulation is important for proper deploy in space and configuration in function of facilities to make them a cohesive and supportive system to meet users’ operation needs. Based on requirement analysis, we propose a framework to combine GIS and Agent simulation to overcome the shortness in temporal analysis and task simulation of traditional GIS. In this framework, Agent based simulation runs as a service on the server, exposes basic simulation functions, such as scenario configuration, simulation control, and simulation data retrieval to installation planners. At the same time, the simulation service is able to utilize various kinds of geoprocessing services in Agents’ process logic to make sophisticated spatial inferences and analysis. This simulation-as-a-service framework has many potential benefits, such as easy-to-use, on-demand, shared understanding, and boosted performances. At the end, we present a preliminary implement of this concept using ArcGIS javascript api 4.0 and ArcGIS for server, showing how trip planning and driving can be carried out by agents.

Image formation simulation for computer-aided inspection planning of machine vision systems

Science.gov (United States)

Irgenfried, Stephan; Bergmann, Stephan; Mohammadikaji, Mahsa; Beyerer, Jürgen; Dachsbacher, Carsten; Wörn, Heinz

2017-06-01

In this work, a simulation toolset for Computer Aided Inspection Planning (CAIP) of systems for automated optical inspection (AOI) is presented along with a versatile two-robot-setup for verification of simulation and system planning results. The toolset helps to narrow down the large design space of optical inspection systems in interaction with a system expert. The image formation taking place in optical inspection systems is simulated using GPU-based real time graphics and high quality off-line-rendering. The simulation pipeline allows a stepwise optimization of the system, from fast evaluation of surface patch visibility based on real time graphics up to evaluation of image processing results based on off-line global illumination calculation. A focus of this work is on the dependency of simulation quality on measuring, modeling and parameterizing the optical surface properties of the object to be inspected. The applicability to real world problems is demonstrated by taking the example of planning a 3D laser scanner application. Qualitative and quantitative comparison results of synthetic and real images are presented.

Projected change in characteristics of near surface temperature inversions for southeast Australia

Science.gov (United States)

Ji, Fei; Evans, Jason Peter; Di Luca, Alejandro; Jiang, Ningbo; Olson, Roman; Fita, Lluis; Argüeso, Daniel; Chang, Lisa T.-C.; Scorgie, Yvonne; Riley, Matt

2018-05-01

Air pollution has significant impacts on human health. Temperature inversions, especially near surface temperature inversions, can amplify air pollution by preventing convective movements and trapping pollutants close to the ground, thus decreasing air quality and increasing health issues. This effect of temperature inversions implies that trends in their frequency, strength and duration can have important implications for air quality. In this study, we evaluate the ability of three reanalysis-driven high-resolution regional climate model (RCM) simulations to represent near surface inversions at 9 sounding sites in southeast Australia. Then we use outputs of 12 historical and future RCM simulations (each with three time periods: 1990-2009, 2020-2039, and 2060-2079) from the NSW/ACT (New South Wales/Australian Capital Territory) Regional Climate Modelling (NARCliM) project to investigate changes in near surface temperature inversions. The results show that there is a substantial increase in the strength of near surface temperature inversions over southeast Australia which suggests that future inversions may intensify poor air quality events. Near surface inversions and their future changes have clear seasonal and diurnal variations. The largest differences between simulations are associated with the driving GCMs, suggesting that the large-scale circulation plays a dominant role in near surface inversion strengths.

The Paper Airplane Challenge: A Market Economy Simulation. Lesson Plan.

Science.gov (United States)

Owens, Kimberly

This lesson plan features a classroom simulation that helps students understand the characteristics of a market economic system. The lesson plan states a purpose; cites student objectives; suggests a time duration; lists materials needed; and details a step-by-step teaching procedure. The "Paper Airplane Challenge" handout is attached. (BT)

Optimization of Gamma Knife treatment planning via guided evolutionary simulated annealing

International Nuclear Information System (INIS)

Zhang Pengpeng; Dean, David; Metzger, Andrew; Sibata, Claudio

2001-01-01

We present a method for generating optimized Gamma Knife trade mark sign (Elekta, Stockholm, Sweden) radiosurgery treatment plans. This semiautomatic method produces a highly conformal shot packing plan for the irradiation of an intracranial tumor. We simulate optimal treatment planning criteria with a probability function that is linked to every voxel in a volumetric (MR or CT) region of interest. This sigmoidal P + parameter models the requirement of conformality (i.e., tumor ablation and normal tissue sparing). After determination of initial radiosurgery treatment parameters, a guided evolutionary simulated annealing (GESA) algorithm is used to find the optimal size, position, and weight for each shot. The three-dimensional GESA algorithm searches the shot parameter space more thoroughly than is possible during manual shot packing and provides one plan that is suitable to the treatment criteria of the attending neurosurgeon and radiation oncologist. The result is a more conformal plan, which also reduces redundancy, and saves treatment administration time

Thermal measurements and inverse techniques

CERN Document Server

Orlande, Helcio RB; Maillet, Denis; Cotta, Renato M

2011-01-01

With its uncommon presentation of instructional material regarding mathematical modeling, measurements, and solution of inverse problems, Thermal Measurements and Inverse Techniques is a one-stop reference for those dealing with various aspects of heat transfer. Progress in mathematical modeling of complex industrial and environmental systems has enabled numerical simulations of most physical phenomena. In addition, recent advances in thermal instrumentation and heat transfer modeling have improved experimental procedures and indirect measurements for heat transfer research of both natural phe

Inverse Kinematics With Closed Form Solution For Denso Robot Manipulator

OpenAIRE

Ikhsan Eka Prasetia; Trihastuti Agustinah

2015-01-01

In this paper, the forward kinematics and inverse kinematics used on the Denso robot manipulator which has a 6-DOF. The forward kinematics will result in the desired position by end-effector, while inverse kinematics produce angel on each joint. Inverse kinematics problem are very difficult, therefor to obtain the solution of inverse kinematics using closed form solution with geometry approach. The simulation result obtained from forward kinematics and inverse kinematics is determining desire...

Tectonic forward modelling of positive inversion structures

Energy Technology Data Exchange (ETDEWEB)

Brandes, C. [Leibniz Univ. Hannover (Germany). Inst. fuer Geologie; Schmidt, C. [Landesamt fuer Bergbau, Energie und Geologie (LBEG), Hannover (Germany)

2013-08-01

Positive tectonic inversion structures are common features that were recognized in many deformed sedimentary basins (Lowell, 1995). They are characterized by a two phase fault evolution, where initial normal faulting was followed by reverse faulting along the same fault, accompanied by the development of hanging wall deformation. Analysing the evolution of such inversion structures is important for understanding the tectonics of sedimentary basins and the formation of hydrocarbon traps. We used a 2D tectonic forward modelling approach to simulate the stepwise structural evolution of inversion structures in cross-section. The modelling was performed with the software FaultFold Forward v. 6, which is based on trishear kinematics (Zehnder and Allmendinger, 2000). Key aspect of the study was to derive the controlling factors for the geometry of inversion structures. The simulation results show, that the trishear approach is able to reproduce the geometry of tectonic inversion structures in a realistic way. This implies that inversion structures are simply fault-related folds that initiated as extensional fault-propagation folds, which were subsequently transformed into compressional fault-propagation folds when the stress field changed. The hanging wall deformation is a consequence of the decrease in slip towards the tip line of the fault. Trishear angle and propagation-to-slip ratio are the key controlling factors for the geometry of the fault-related deformation. We tested trishear angles in the range of 30 - 60 and propagation-to-slip ratios between 1 and 2 in increments of 0.1. Small trishear angles and low propagation-to-slip ratios produced tight folds, whereas large trishear angles and high propagation-to-slip ratios led to more open folds with concentric shapes. This has a direct effect on the size and geometry of potential hydrocarbon traps. The 2D simulations can be extended to a pseudo 3D approach, where a set of parallel cross-sections is used to describe

Recurrent Neural Network for Computing Outer Inverse.

Science.gov (United States)

Živković, Ivan S; Stanimirović, Predrag S; Wei, Yimin

2016-05-01

Two linear recurrent neural networks for generating outer inverses with prescribed range and null space are defined. Each of the proposed recurrent neural networks is based on the matrix-valued differential equation, a generalization of dynamic equations proposed earlier for the nonsingular matrix inversion, the Moore-Penrose inversion, as well as the Drazin inversion, under the condition of zero initial state. The application of the first approach is conditioned by the properties of the spectrum of a certain matrix; the second approach eliminates this drawback, though at the cost of increasing the number of matrix operations. The cases corresponding to the most common generalized inverses are defined. The conditions that ensure stability of the proposed neural network are presented. Illustrative examples present the results of numerical simulations.

Multiparameter Optimization for Electromagnetic Inversion Problem

Directory of Open Access Journals (Sweden)

M. Elkattan

2017-10-01

Full Text Available Electromagnetic (EM methods have been extensively used in geophysical investigations such as mineral and hydrocarbon exploration as well as in geological mapping and structural studies. In this paper, we developed an inversion methodology for Electromagnetic data to determine physical parameters of a set of horizontal layers. We conducted Forward model using transmission line method. In the inversion part, we solved multi parameter optimization problem where, the parameters are conductivity, dielectric constant, and permeability of each layer. The optimization problem was solved by simulated annealing approach. The inversion methodology was tested using a set of models representing common geological formations.

Inversion of a lateral log using neural networks

International Nuclear Information System (INIS)

Garcia, G.; Whitman, W.W.

1992-01-01

In this paper a technique using neural networks is demonstrated for the inversion of a lateral log. The lateral log is simulated by a finite difference method which in turn is used as an input to a backpropagation neural network. An initial guess earth model is generated from the neural network, which is then input to a Marquardt inversion. The neural network reacts to gross and subtle data features in actual logs and produces a response inferred from the knowledge stored in the network during a training process. The neural network inversion of lateral logs is tested on synthetic and field data. Tests using field data resulted in a final earth model whose simulated lateral is in good agreement with the actual log data

Simulation-optimization model for production planning in the blood supply chain.

Science.gov (United States)

Osorio, Andres F; Brailsford, Sally C; Smith, Honora K; Forero-Matiz, Sonia P; Camacho-Rodríguez, Bernardo A

2017-12-01

Production planning in the blood supply chain is a challenging task. Many complex factors such as uncertain supply and demand, blood group proportions, shelf life constraints and different collection and production methods have to be taken into account, and thus advanced methodologies are required for decision making. This paper presents an integrated simulation-optimization model to support both strategic and operational decisions in production planning. Discrete-event simulation is used to represent the flows through the supply chain, incorporating collection, production, storing and distribution. On the other hand, an integer linear optimization model running over a rolling planning horizon is used to support daily decisions, such as the required number of donors, collection methods and production planning. This approach is evaluated using real data from a blood center in Colombia. The results show that, using the proposed model, key indicators such as shortages, outdated units, donors required and cost are improved.

Testing earthquake source inversion methodologies

KAUST Repository

Page, Morgan T.

2011-01-01

Source Inversion Validation Workshop; Palm Springs, California, 11-12 September 2010; Nowadays earthquake source inversions are routinely performed after large earthquakes and represent a key connection between recorded seismic and geodetic data and the complex rupture process at depth. The resulting earthquake source models quantify the spatiotemporal evolution of ruptures. They are also used to provide a rapid assessment of the severity of an earthquake and to estimate losses. However, because of uncertainties in the data, assumed fault geometry and velocity structure, and chosen rupture parameterization, it is not clear which features of these source models are robust. Improved understanding of the uncertainty and reliability of earthquake source inversions will allow the scientific community to use the robust features of kinematic inversions to more thoroughly investigate the complexity of the rupture process and to better constrain other earthquakerelated computations, such as ground motion simulations and static stress change calculations.

Spin-ice behavior of three-dimensional inverse opal-like magnetic structures: Micromagnetic simulations

Science.gov (United States)

Dubitskiy, I. S.; Syromyatnikov, A. V.; Grigoryeva, N. A.; Mistonov, A. A.; Sapoletova, N. A.; Grigoriev, S. V.

2017-11-01

We perform micromagnetic simulations of the magnetization distribution in inverse opal-like structures (IOLS) made from ferromagnetic materials (nickel and cobalt). It is shown that the unit cell of these complex structures, whose characteristic length is approximately 700 nm, can be divided into a set of structural elements some of which behave like Ising-like objects. A spin-ice behavior of IOLS is observed in a broad range of external magnetic fields. Numerical results describe successfully the experimental hysteresis curves of the magnetization in Ni- and Co-based IOLS. We conclude that ferromagnetic IOLS can be considered as the first realization of three-dimensional artificial spin ice. The problem is discussed of optimal geometrical properties and material characteristics of IOLS for the spin-ice rule fulfillment.

Simulation model for planning metallurgical treatment of large-size billets

International Nuclear Information System (INIS)

Timofeev, M.A.; Echeistova, L.A.; Kuznetsov, V.G.; Semakin, S.V.; Krivonogov, A.B.

1989-01-01

The computerized simulation system ''Ritm'' for planning metallurgical treatment of billets is developed. Three principles, specifying the organization structure of the treatment cycle are formulated as follows: a cycling principle, a priority principle and a principle of group treatment. The ''Ritm'' software consists of three independent operating systems: preparation of source data, simulation, data output

Theoretical study on the inverse modeling of deep body temperature measurement

International Nuclear Information System (INIS)

Huang, Ming; Chen, Wenxi

2012-01-01

We evaluated the theoretical aspects of monitoring the deep body temperature distribution with the inverse modeling method. A two-dimensional model was built based on anatomical structure to simulate the human abdomen. By integrating biophysical and physiological information, the deep body temperature distribution was estimated from cutaneous surface temperature measurements using an inverse quasilinear method. Simulations were conducted with and without the heat effect of blood perfusion in the muscle and skin layers. The results of the simulations showed consistently that the noise characteristics and arrangement of the temperature sensors were the major factors affecting the accuracy of the inverse solution. With temperature sensors of 0.05 °C systematic error and an optimized 16-sensor arrangement, the inverse method could estimate the deep body temperature distribution with an average absolute error of less than 0.20 °C. The results of this theoretical study suggest that it is possible to reconstruct the deep body temperature distribution with the inverse method and that this approach merits further investigation. (paper)

Numerical Simulations of an Inversion Fog Event in the Salt Lake Valley during the MATERHORN-Fog Field Campaign

Science.gov (United States)

Chachere, Catherine N.; Pu, Zhaoxia

2018-01-01

An advanced research version of the Weather Research and Forecasting (WRF) Model is employed to simulate a wintertime inversion fog event in the Salt Lake Valley during the Mountain Terrain Atmospheric Modeling and Observations Program (MATERHORN) field campaign during January 2015. Simulation results are compared to observations obtained from the field program. The sensitivity of numerical simulations to available cloud microphysical (CM), planetary boundary layer (PBL), radiation, and land surface models (LSMs) is evaluated. The influence of differing visibility algorithms and initialization times on simulation results is also examined. Results indicate that the numerical simulations of the fog event are sensitive to the choice of CM, PBL, radiation, and LSM as well as the visibility algorithm and initialization time. Although the majority of experiments accurately captured the synoptic setup environment, errors were found in most experiments within the boundary layer, specifically a 3° warm bias in simulated surface temperatures compared to observations. Accurate representation of surface and boundary layer variables are vital in correctly predicting fog in the numerical model.

Inverse planning of intensity modulated proton therapy

International Nuclear Information System (INIS)

Nill, S.; Oelfke, U.; Bortfeld, T.

2004-01-01

A common requirement of radiation therapy is that treatment planning for different radiation modalities is devised on the basis of the same treatment planning system (TPS). The present study presents a novel multi-modal TPS with separate modules for the dose calculation, the optimization engine and the graphical user interface, which allows to integrate different treatment modalities. For heavy-charged particles, both most promising techniques, the distal edge tracking (DET) and the 3-dimensional scanning (3D) technique can be optimized. As a first application, the quality of optimized intensity-modulated treatment plans for photons (IMXT) and protons (IMPT) was analyzed in one clinical case on the basis of the achieved physical dose distributions. A comparison of the proton plans with the photon plans showed no significant improvement in terms of target volume dose, however there was an improvement in terms of organs at risk as well as a clear reduction of the total integral dose. For the DET technique, it is possible to create a treatment plan with almost the same quality of the 3D technique, however with a clearly reduced number (factor of 5) of beam spots as well as a reduced optimization time. Due to its modular design, the system can be easily expanded to more sophisticated dose-calculation algorithms or to modeling of biological effects. (orig.) [de

Simulations of nuclear reactions for a future HIE-ISOLDE spectrometer

Energy Technology Data Exchange (ETDEWEB)

Tveten, Gry [University of Oslo (Norway); CERN (Switzerland); Cederkall, Joakim [Lund University (Sweden); CERN (Switzerland); Blumenfeld, Yorick [CERN (Switzerland)

2009-07-01

The planned High Intensity and Energy (HIE) upgrade of the radioactive beam facility ISOLDE will enable post-acceleration of radioactive beams up to an energy of about 10 MeV/u, thus opening the door to nuclear reaction studies. In the case of transfer reactions in inverse kinematics a recoil separator is often well suited or even needed to tell recoils and beam apart and to select the exit channel or to do spectroscopic studies. Two different types of spectrometer designs are being considered for HIE-ISOLDE, namely a recoil mass separator or a ray-tracing type of spectrometer. A set of nuclear transfer reactions in inverse kinematics have been simulated using realistic parameters for HIE-ISOLDE. The performance of the two types of spectrometer designs is compared and their scientific possibilities and limitations discussed based on the simulation results. To evaluate the validity of the simulations a data set from PRISMA at LNL is also compared with simulation results and a comparison between simulations and these data will be presented.

A new hybrid-FBP inversion algorithm with inverse distance backprojection weight for CT reconstruction

Energy Technology Data Exchange (ETDEWEB)

Narasimhadhan, A.V.; Rajgopal, Kasi

2011-07-01

This paper presents a new hybrid filtered backprojection (FBP) algorithm for fan-beam and cone-beam scan. The hybrid reconstruction kernel is the sum of the ramp and Hilbert filters. We modify the redundancy weighting function to reduce the inverse square distance weighting in the backprojection to inverse distance weight. The modified weight also eliminates the derivative associated with the Hilbert filter kernel. Thus, the proposed reconstruction algorithm has the advantages of the inverse distance weight in the backprojection. We evaluate the performance of the new algorithm in terms of the magnitude level and uniformity in noise for the fan-beam geometry. The computer simulations show that the spatial resolution is nearly identical to the standard fan-beam ramp filtered algorithm while the noise is spatially uniform and the noise variance is reduced. (orig.)

Treatment planning in radiosurgery: parallel Monte Carlo simulation software

Energy Technology Data Exchange (ETDEWEB)

Scielzo, G [Galliera Hospitals, Genova (Italy). Dept. of Hospital Physics; Grillo Ruggieri, F [Galliera Hospitals, Genova (Italy) Dept. for Radiation Therapy; Modesti, M; Felici, R [Electronic Data System, Rome (Italy); Surridge, M [University of South Hampton (United Kingdom). Parallel Apllication Centre

1995-12-01

The main objective of this research was to evaluate the possibility of direct Monte Carlo simulation for accurate dosimetry with short computation time. We made us of: graphics workstation, linear accelerator, water, PMMA and anthropomorphic phantoms, for validation purposes; ionometric, film and thermo-luminescent techniques, for dosimetry; treatment planning system for comparison. Benchmarking results suggest that short computing times can be obtained with use of the parallel version of EGS4 that was developed. Parallelism was obtained assigning simulation incident photons to separate processors, and the development of a parallel random number generator was necessary. Validation consisted in: phantom irradiation, comparison of predicted and measured values good agreement in PDD and dose profiles. Experiments on anthropomorphic phantoms (with inhomogeneities) were carried out, and these values are being compared with results obtained with the conventional treatment planning system.

Bayesian seismic AVO inversion

Energy Technology Data Exchange (ETDEWEB)

Buland, Arild

2002-07-01

A new linearized AVO inversion technique is developed in a Bayesian framework. The objective is to obtain posterior distributions for P-wave velocity, S-wave velocity and density. Distributions for other elastic parameters can also be assessed, for example acoustic impedance, shear impedance and P-wave to S-wave velocity ratio. The inversion algorithm is based on the convolutional model and a linearized weak contrast approximation of the Zoeppritz equation. The solution is represented by a Gaussian posterior distribution with explicit expressions for the posterior expectation and covariance, hence exact prediction intervals for the inverted parameters can be computed under the specified model. The explicit analytical form of the posterior distribution provides a computationally fast inversion method. Tests on synthetic data show that all inverted parameters were almost perfectly retrieved when the noise approached zero. With realistic noise levels, acoustic impedance was the best determined parameter, while the inversion provided practically no information about the density. The inversion algorithm has also been tested on a real 3-D dataset from the Sleipner Field. The results show good agreement with well logs but the uncertainty is high. The stochastic model includes uncertainties of both the elastic parameters, the wavelet and the seismic and well log data. The posterior distribution is explored by Markov chain Monte Carlo simulation using the Gibbs sampler algorithm. The inversion algorithm has been tested on a seismic line from the Heidrun Field with two wells located on the line. The uncertainty of the estimated wavelet is low. In the Heidrun examples the effect of including uncertainty of the wavelet and the noise level was marginal with respect to the AVO inversion results. We have developed a 3-D linearized AVO inversion method with spatially coupled model parameters where the objective is to obtain posterior distributions for P-wave velocity, S

Evaluation of concave dose distributions created using an inverse planning system

International Nuclear Information System (INIS)

Hunt, Margie A.; Hsiung, C.-Y.; Spirou, Spirodon V.; Chui, C.-S.; Amols, Howard I.; Ling, Clifton C.

2002-01-01

Purpose: To evaluate and develop optimum inverse treatment planning strategies for the treatment of concave targets adjacent to normal tissue structures. Methods and Materials: Optimized dose distributions were designed using an idealized geometry consisting of a cylindrical phantom with a concave kidney-shaped target (PTV) and cylindrical normal tissues (NT) placed 5-13 mm from the target. Targets with radii of curvature from 1 to 2.75 cm were paired with normal tissues with radii between 0.5 and 2.25 cm. The target was constrained to a prescription dose of 100% and minimum and maximum doses of 95% and 105% with relative penalties of 25. Maximum dose constraint parameters for the NT varied from 10% to 70% with penalties from 10 to 1000. Plans were evaluated using the PTV uniformity index (PTV D max /PTV D 95 ) and maximum normal tissue doses (NT D max /PTV D 95 ). Results: In nearly all situations, the achievable PTV uniformity index and the maximum NT dose exceeded the corresponding constraints. This was particularly true for small PTV-NT separations (5-8 mm) or strict NT dose constraints (10%-30%), where the achievable doses differed from the requested by 30% or more. The same constraint parameters applied to different PTV-NT separations yielded different dose distributions. For most geometries, a range of constraints could be identified that would lead to acceptable plans. The optimization results were fairly independent of beam energy and radius of curvature, but improved as the number of beams increased, particularly for small PTV-NT separations or strict dose constraints. Conclusion: Optimized dose distributions are strongly affected by both the constraint parameters and target-normal tissue geometry. Standard site-specific constraint templates can serve as a starting point for optimization, but the final constraints must be determined iteratively for individual patients. A strategy whereby NT constraints and penalties are modified until the highest

Clinical treatment planning for stereotactic radiotherapy, evaluation by Monte Carlo simulation

International Nuclear Information System (INIS)

Kairn, T.; Aland, T.; Kenny, J.; Knight, R.T.; Crowe, S.B.; Langton, C.M.; Franich, R.D.; Johnston, P.N.

2010-01-01

Full text: This study uses re-evaluates the doses delivered by a series of clinical stereotactic radiotherapy treatments, to test the accuracy of treatment planning predictions for very small radiation fields. Stereotactic radiotherapy treatment plans for meningiomas near the petrous temporal bone and the foramen magnum (incorp rating fields smaller than I c m2) were examined using Monte Carlo simulations. Important differences between treatment planning predictions and Monte Carlo calculations of doses delivered to stereotactic radiotherapy patients are apparent. For example, in one case the Monte Carlo calculation shows that the delivery a planned meningioma treatment would spare the patient's critical structures (eyes, brainstem) more effectively than the treatment plan predicted, and therefore suggests that this patient could safely receive an increased dose to their tumour. Monte Carlo simulations can be used to test the dose predictions made by a conventional treatment planning system, for dosimetrically challenging small fields, and can thereby suggest valuable modifications to clinical treatment plans. This research was funded by the Wesley Research Institute, Australia. The authors wish to thank Andrew Fielding and David Schlect for valuable discussions of aspects of this work. The authors are also grateful to Muhammad Kakakhel, for assisting with the design and calibration of our linear accelerator model, and to the stereotactic radiation therapy team at Premion, who designed the treatment plans. Computational resources and services used in this work were provided by the HPC and Research Support Unit, QUT, Brisbane, Australia. (author)

Mesoscale inversion of carbon sources and sinks

International Nuclear Information System (INIS)

Lauvaux, T.

2008-01-01

Inverse methods at large scales are used to infer the spatial variability of carbon sources and sinks over the continents but their uncertainties remain large. Atmospheric concentrations integrate the surface flux variability but atmospheric transport models at low resolution are not able to simulate properly the local atmospheric dynamics at the measurement sites. However, the inverse estimates are more representative of the large spatial heterogeneity of the ecosystems compared to direct flux measurements. Top-down and bottom-up methods that aim at quantifying the carbon exchanges between the surface and the atmosphere correspond to different scales and are not easily comparable. During this phD, a mesoscale inverse system was developed to correct carbon fluxes at 8 km resolution. The high resolution transport model MesoNH was used to simulate accurately the variability of the atmospheric concentrations, which allowed us to reduce the uncertainty of the retrieved fluxes. All the measurements used here were observed during the intensive regional campaign CERES of May and June 2005, during which several instrumented towers measured CO 2 concentrations and fluxes in the South West of France. Airborne measurements allowed us to observe concentrations at high altitude but also CO 2 surface fluxes over large parts of the domain. First, the capacity of the inverse system to correct the CO 2 fluxes was estimated using pseudo-data experiments. The largest fraction of the concentration variability was attributed to regional surface fluxes over an area of about 300 km around the site locations depending on the meteorological conditions. Second, an ensemble of simulations allowed us to define the spatial and temporal structures of the transport errors. Finally, the inverse fluxes at 8 km resolution were compared to direct flux measurements. The inverse system has been validated in space and time and showed an improvement of the first guess fluxes from a vegetation model

Frequency domain, waveform inversion of laboratory crosswell radar data

Science.gov (United States)

Ellefsen, Karl J.; Mazzella, Aldo T.; Horton, Robert J.; McKenna, Jason R.

2010-01-01

A new waveform inversion for crosswell radar is formulated in the frequency-domain for a 2.5D model. The inversion simulates radar waves using the vector Helmholtz equation for electromagnetic waves. The objective function is minimized using a backpropagation method suitable for a 2.5D model. The inversion is tested by processing crosswell radar data collected in a laboratory tank. The estimated model is consistent with the known electromagnetic properties of the tank. The formulation for the 2.5D model can be extended to inversions of acoustic and elastic data.

WE-H-BRC-09: Simulated Errors in Mock Radiotherapy Plans to Quantify the Effectiveness of the Physics Plan Review

International Nuclear Information System (INIS)

Gopan, O; Kalet, A; Smith, W; Hendrickson, K; Kim, M; Young, L; Nyflot, M; Chvetsov, A; Phillips, M; Ford, E

2016-01-01

Purpose: A standard tool for ensuring the quality of radiation therapy treatments is the initial physics plan review. However, little is known about its performance in practice. The goal of this study is to measure the effectiveness of physics plan review by introducing simulated errors into “mock” treatment plans and measuring the performance of plan review by physicists. Methods: We generated six mock treatment plans containing multiple errors. These errors were based on incident learning system data both within the department and internationally (SAFRON). These errors were scored for severity and frequency. Those with the highest scores were included in the simulations (13 errors total). Observer bias was minimized using a multiple co-correlated distractor approach. Eight physicists reviewed these plans for errors, with each physicist reviewing, on average, 3/6 plans. The confidence interval for the proportion of errors detected was computed using the Wilson score interval. Results: Simulated errors were detected in 65% of reviews [51–75%] (95% confidence interval [CI] in brackets). The following error scenarios had the highest detection rates: incorrect isocenter in DRRs/CBCT (91% [73–98%]) and a planned dose different from the prescribed dose (100% [61–100%]). Errors with low detection rates involved incorrect field parameters in record and verify system (38%, [18–61%]) and incorrect isocenter localization in planning system (29% [8–64%]). Though pre-treatment QA failure was reliably identified (100%), less than 20% of participants reported the error that caused the failure. Conclusion: This is one of the first quantitative studies of error detection. Although physics plan review is a key safety measure and can identify some errors with high fidelity, others errors are more challenging to detect. This data will guide future work on standardization and automation. Creating new checks or improving existing ones (i.e., via automation) will help in

WE-H-BRC-09: Simulated Errors in Mock Radiotherapy Plans to Quantify the Effectiveness of the Physics Plan Review

Energy Technology Data Exchange (ETDEWEB)

Gopan, O; Kalet, A; Smith, W; Hendrickson, K; Kim, M; Young, L; Nyflot, M; Chvetsov, A; Phillips, M; Ford, E [University of Washington, Seattle, WA (United States)

2016-06-15

Purpose: A standard tool for ensuring the quality of radiation therapy treatments is the initial physics plan review. However, little is known about its performance in practice. The goal of this study is to measure the effectiveness of physics plan review by introducing simulated errors into “mock” treatment plans and measuring the performance of plan review by physicists. Methods: We generated six mock treatment plans containing multiple errors. These errors were based on incident learning system data both within the department and internationally (SAFRON). These errors were scored for severity and frequency. Those with the highest scores were included in the simulations (13 errors total). Observer bias was minimized using a multiple co-correlated distractor approach. Eight physicists reviewed these plans for errors, with each physicist reviewing, on average, 3/6 plans. The confidence interval for the proportion of errors detected was computed using the Wilson score interval. Results: Simulated errors were detected in 65% of reviews [51–75%] (95% confidence interval [CI] in brackets). The following error scenarios had the highest detection rates: incorrect isocenter in DRRs/CBCT (91% [73–98%]) and a planned dose different from the prescribed dose (100% [61–100%]). Errors with low detection rates involved incorrect field parameters in record and verify system (38%, [18–61%]) and incorrect isocenter localization in planning system (29% [8–64%]). Though pre-treatment QA failure was reliably identified (100%), less than 20% of participants reported the error that caused the failure. Conclusion: This is one of the first quantitative studies of error detection. Although physics plan review is a key safety measure and can identify some errors with high fidelity, others errors are more challenging to detect. This data will guide future work on standardization and automation. Creating new checks or improving existing ones (i.e., via automation) will help in

Comparison of treatments of steep and shoot generated by different inverse planning systems; Comparacion de tratamiento de steep and shoot generados por diferentes sistemas de planificacion inversa

Energy Technology Data Exchange (ETDEWEB)

Perez Moreno, J. M.; Zucca Aparicio, D.; Fernandez Leton, P.; Garcia Ruiz-Zorrilla, J.; Minambres Moro, A.

2011-07-01

The problem of IMRT treatments with the technique Steep and Shoot or static is the number of segments and monitor units used in the treatment. These parameters depend largely on the inverse planning system which determines treatment. Are evaluated three commercial planning systems, with each one performing clinical dosimetry for the same series of patients. Dosimetric results are compared, UM calculated and number of segments.

SU-E-T-175: Clinical Evaluations of Monte Carlo-Based Inverse Treatment Plan Optimization for Intensity Modulated Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Chi, Y; Li, Y; Tian, Z; Gu, X; Jiang, S; Jia, X [UT Southwestern Medical Center, Dallas, TX (United States)

2015-06-15

Purpose: Pencil-beam or superposition-convolution type dose calculation algorithms are routinely used in inverse plan optimization for intensity modulated radiation therapy (IMRT). However, due to their limited accuracy in some challenging cases, e.g. lung, the resulting dose may lose its optimality after being recomputed using an accurate algorithm, e.g. Monte Carlo (MC). It is the objective of this study to evaluate the feasibility and advantages of a new method to include MC in the treatment planning process. Methods: We developed a scheme to iteratively perform MC-based beamlet dose calculations and plan optimization. In the MC stage, a GPU-based dose engine was used and the particle number sampled from a beamlet was proportional to its optimized fluence from the previous step. We tested this scheme in four lung cancer IMRT cases. For each case, the original plan dose, plan dose re-computed by MC, and dose optimized by our scheme were obtained. Clinically relevant dosimetric quantities in these three plans were compared. Results: Although the original plan achieved a satisfactory PDV dose coverage, after re-computing doses using MC method, it was found that the PTV D95% were reduced by 4.60%–6.67%. After re-optimizing these cases with our scheme, the PTV coverage was improved to the same level as in the original plan, while the critical OAR coverages were maintained to clinically acceptable levels. Regarding the computation time, it took on average 144 sec per case using only one GPU card, including both MC-based beamlet dose calculation and treatment plan optimization. Conclusion: The achieved dosimetric gains and high computational efficiency indicate the feasibility and advantages of the proposed MC-based IMRT optimization method. Comprehensive validations in more patient cases are in progress.

Toward Inverse Control of Physics-Based Sound Synthesis

Science.gov (United States)

Pfalz, A.; Berdahl, E.

2017-05-01

Long Short-Term Memory networks (LSTMs) can be trained to realize inverse control of physics-based sound synthesizers. Physics-based sound synthesizers simulate the laws of physics to produce output sound according to input gesture signals. When a user's gestures are measured in real time, she or he can use them to control physics-based sound synthesizers, thereby creating simulated virtual instruments. An intriguing question is how to program a computer to learn to play such physics-based models. This work demonstrates that LSTMs can be trained to accomplish this inverse control task with four physics-based sound synthesizers.

Full-Physics Inverse Learning Machine for Satellite Remote Sensing Retrievals

Science.gov (United States)

Loyola, D. G.

2017-12-01

The satellite remote sensing retrievals are usually ill-posed inverse problems that are typically solved by finding a state vector that minimizes the residual between simulated data and real measurements. The classical inversion methods are very time-consuming as they require iterative calls to complex radiative-transfer forward models to simulate radiances and Jacobians, and subsequent inversion of relatively large matrices. In this work we present a novel and extremely fast algorithm for solving inverse problems called full-physics inverse learning machine (FP-ILM). The FP-ILM algorithm consists of a training phase in which machine learning techniques are used to derive an inversion operator based on synthetic data generated using a radiative transfer model (which expresses the "full-physics" component) and the smart sampling technique, and an operational phase in which the inversion operator is applied to real measurements. FP-ILM has been successfully applied to the retrieval of the SO2 plume height during volcanic eruptions and to the retrieval of ozone profile shapes from UV/VIS satellite sensors. Furthermore, FP-ILM will be used for the near-real-time processing of the upcoming generation of European Sentinel sensors with their unprecedented spectral and spatial resolution and associated large increases in the amount of data.

Inverse problem of Ocean Acoustic Tomography (OAT) - A numerical experiment

Digital Repository Service at National Institute of Oceanography (India)

Murty, T.V.R.; Somayajulu, Y.K.; Mahadevan, R.; Murty, C.S.

Acoustic model simulation experiments related to the forward and inverse aspects of ocean tomography have been taken up with a view to estimate the vertical sound speed field by inverting the travel time data. Two methods of inversion have been...

Multi-institutional comparison of simulated treatment delivery errors in ssIMRT, manually planned VMAT and autoplan-VMAT plans for nasopharyngeal radiotherapy

DEFF Research Database (Denmark)

Pogson, Elise M; Aruguman, Sankar; Hansen, Christian R

2017-01-01

PURPOSE: To quantify the impact of simulated errors for nasopharynx radiotherapy across multiple institutions and planning techniques (auto-plan generated Volumetric Modulated Arc Therapy (ap-VMAT), manually planned VMAT (mp-VMAT) and manually planned step and shoot Intensity Modulated Radiation...... Therapy (mp-ssIMRT)). METHODS: Ten patients were retrospectively planned with VMAT according to three institution's protocols. Within one institution two further treatment plans were generated using differing treatment planning techniques. This resulted in mp-ssIMRT, mp-VMAT, and ap-VMAT plans. Introduced...

Development of a Searchable Database of Cryoablation Simulations for Use in Treatment Planning.

Science.gov (United States)

Boas, F Edward; Srimathveeravalli, Govindarajan; Durack, Jeremy C; Kaye, Elena A; Erinjeri, Joseph P; Ziv, Etay; Maybody, Majid; Yarmohammadi, Hooman; Solomon, Stephen B

2017-05-01

To create and validate a planning tool for multiple-probe cryoablation, using simulations of ice ball size and shape for various ablation probe configurations, ablation times, and types of tissue ablated. Ice ball size and shape was simulated using the Pennes bioheat equation. Five thousand six hundred and seventy different cryoablation procedures were simulated, using 1-6 cryoablation probes and 1-2 cm spacing between probes. The resulting ice ball was measured along three perpendicular axes and recorded in a database. Simulated ice ball sizes were compared to gel experiments (26 measurements) and clinical cryoablation cases (42 measurements). The clinical cryoablation measurements were obtained from a HIPAA-compliant retrospective review of kidney and liver cryoablation procedures between January 2015 and February 2016. Finally, we created a web-based cryoablation planning tool, which uses the cryoablation simulation database to look up the probe spacing and ablation time that produces the desired ice ball shape and dimensions. Average absolute error between the simulated and experimentally measured ice balls was 1 mm in gel experiments and 4 mm in clinical cryoablation cases. The simulations accurately predicted the degree of synergy in multiple-probe ablations. The cryoablation simulation database covers a wide range of ice ball sizes and shapes up to 9.8 cm. Cryoablation simulations accurately predict the ice ball size in multiple-probe ablations. The cryoablation database can be used to plan ablation procedures: given the desired ice ball size and shape, it will find the number and type of probes, probe configuration and spacing, and ablation time required.

Simulation study of HEMT structures with HfO2 cap layer for mitigating inverse piezoelectric effect related device failures

Directory of Open Access Journals (Sweden)

Deepthi Nagulapally

2015-01-01

Full Text Available The Inverse Piezoelectric Effect (IPE is thought to contribute to possible device failure of GaN High Electron Mobility Transistors (HEMTs. Here we focus on a simulation study to probe the possible mitigation of the IPE by reducing the internal electric fields and related elastic energy through the use of high-k materials. Inclusion of a HfO2 “cap layer” above the AlGaN barrier particularly with a partial mesa structure is shown to have potential advantages. Simulations reveal even greater reductions in the internal electric fields by using “field plates” in concert with high-k oxides.

Sci-Fri PM: Radiation Therapy, Planning, Imaging, and Special Techniques - 05: A novel respiratory motion simulation program for VMAT treatment plans: a phantom validation study

Energy Technology Data Exchange (ETDEWEB)

Hubley, Emily; Pierce, Greg; Ploquin, Nicolas [University of Calgary, Tom Baker Cancer Centre, Tom Baker Cancer Centre (Canada)

2016-08-15

Purpose: To develop and validate a computational method to simulate craniocaudal respiratory motion in a VMAT treatment plan. Methods: Three 4DCTs of the QUASAR respiratory motion phantom were acquired with a 2cm water-density spherical tumour embedded in cedar to simulate lung. The phantom was oscillating sinusoidally with an amplitude of 2cm and periods of 3, 4, and 5 seconds. An ITV was contoured and 5mm PTV margin was added. High and a low modulation factor VMAT plans were created for each scan. An in-house program was developed to simulate respiratory motion in the treatment plans by shifting the MLC leaf positions relative to the phantom. Each plan was delivered to the phantom and the dose was measured using Gafchromic film. The measured and calculated plans were compared using an absolute dose gamma analysis (3%/3mm). Results: The average gamma pass rate for the low modulation plan and high modulation plans were 91.1% and 51.4% respectively. The difference between the high and low modulation plans gamma pass rates is likely related to the different sampling frequency of the respiratory curve and the higher MLC leaf speeds in the high modulation plan. A high modulation plan has a slower gantry speed and therefore samples the breathing cycle at a coarser frequency leading to inaccuracies between the measured and planned doses. Conclusion: A simple program, including a novel method for increasing sampling frequency beyond the control point frequency, has been developed to simulate respiratory motion in VMAT plans by shifting the MLC leaf positions.

Sci-Fri PM: Radiation Therapy, Planning, Imaging, and Special Techniques - 05: A novel respiratory motion simulation program for VMAT treatment plans: a phantom validation study

International Nuclear Information System (INIS)

Hubley, Emily; Pierce, Greg; Ploquin, Nicolas

2016-01-01

Purpose: To develop and validate a computational method to simulate craniocaudal respiratory motion in a VMAT treatment plan. Methods: Three 4DCTs of the QUASAR respiratory motion phantom were acquired with a 2cm water-density spherical tumour embedded in cedar to simulate lung. The phantom was oscillating sinusoidally with an amplitude of 2cm and periods of 3, 4, and 5 seconds. An ITV was contoured and 5mm PTV margin was added. High and a low modulation factor VMAT plans were created for each scan. An in-house program was developed to simulate respiratory motion in the treatment plans by shifting the MLC leaf positions relative to the phantom. Each plan was delivered to the phantom and the dose was measured using Gafchromic film. The measured and calculated plans were compared using an absolute dose gamma analysis (3%/3mm). Results: The average gamma pass rate for the low modulation plan and high modulation plans were 91.1% and 51.4% respectively. The difference between the high and low modulation plans gamma pass rates is likely related to the different sampling frequency of the respiratory curve and the higher MLC leaf speeds in the high modulation plan. A high modulation plan has a slower gantry speed and therefore samples the breathing cycle at a coarser frequency leading to inaccuracies between the measured and planned doses. Conclusion: A simple program, including a novel method for increasing sampling frequency beyond the control point frequency, has been developed to simulate respiratory motion in VMAT plans by shifting the MLC leaf positions.

Two-dimensional inversion of MT (magnetotelluric) data; MT ho no nijigen inversion kaiseki

Energy Technology Data Exchange (ETDEWEB)

Ito, S; Okuno, M; Ushijima, K; Mizunaga, H [Kyushu University, Fukuoka (Japan). Faculty of Engineering

1997-05-27

A program has been developed to conduct inversion analysis of two-dimensional model using MT data, accurately. For the developed program, finite element method (FEM) was applied to the section of sequential analysis. A method in which Jacobian matrix is calculated only one first time and is inversely analyzed by fixing this during the repetition, and a method in which Jacobian matrix is corrected at each repetition of inversion analysis, were compared mutually. As a result of the numerical simulation, it was revealed that the Jacobian correction method provided more stable convergence for the simple 2D model, and that the calculation time is almost same as that of the Jacobian fixation method. To confirm the applicability of this program to actually measured data, results obtained from this program were compared with those from the Schlumberger method analysis by using MT data obtained in the Hatchobara geothermal area. Consequently, it was demonstrated that the both are well coincided mutually. 17 refs., 7 figs.

OTRA-Based Multi-Function Inverse Filter Configuration

Directory of Open Access Journals (Sweden)

Abdhesh Kumar Singh

2017-01-01

Full Text Available A new OTRA-based multifunction Inverse filter configuration is presented which is capable of realizing low pass, high pass and band pass filters using only two OTRAs and five to six passive elements. To the best knowledge of the authors, any inverse filter configuration using OTRAs has not been reported in the literature earlier. The effect of the major parasitics of the OTRAs and their effect on the performance filter have been investigated and measured through simulation results and Monte-Carlo analysis. The workability of the proposed circuits has been confirmed by SPICE simulations using CMOS-based-OTRA realizable in 0.18 µm CMOS technology. The proposed circuits are the only ones which provide simultaneously the following features: use of reasonable number of active elements (only 2, realizability of all the three basic filter functions, employment of all virtually grounded resistors and capacitors and tunability of all filter parameters (except gain factor, H_0 for inverse high pass. The centre/cut-off frequency of the various filter circuits lying in the vicinity of 1 MHz have been found to be realizable, which has been verified through SPICE simulation results and have been found to be in good agreement with the theoretical results.

Enhanced Simulated Annealing for Solving Aggregate Production Planning

Directory of Open Access Journals (Sweden)

Mohd Rizam Abu Bakar

2016-01-01

Full Text Available Simulated annealing (SA has been an effective means that can address difficulties related to optimisation problems. SA is now a common discipline for research with several productive applications such as production planning. Due to the fact that aggregate production planning (APP is one of the most considerable problems in production planning, in this paper, we present multiobjective linear programming model for APP and optimised by SA. During the course of optimising for the APP problem, it uncovered that the capability of SA was inadequate and its performance was substandard, particularly for a sizable controlled APP problem with many decision variables and plenty of constraints. Since this algorithm works sequentially then the current state will generate only one in next state that will make the search slower and the drawback is that the search may fall in local minimum which represents the best solution in only part of the solution space. In order to enhance its performance and alleviate the deficiencies in the problem solving, a modified SA (MSA is proposed. We attempt to augment the search space by starting with N+1 solutions, instead of one solution. To analyse and investigate the operations of the MSA with the standard SA and harmony search (HS, the real performance of an industrial company and simulation are made for evaluation. The results show that, compared to SA and HS, MSA offers better quality solutions with regard to convergence and accuracy.

Conventional treatment planning optimization using simulated annealing

International Nuclear Information System (INIS)

Morrill, S.M.; Langer, M.; Lane, R.G.

1995-01-01

Purpose: Simulated annealing (SA) allows for the implementation of realistic biological and clinical cost functions into treatment plan optimization. However, a drawback to the clinical implementation of SA optimization is that large numbers of beams appear in the final solution, some with insignificant weights, preventing the delivery of these optimized plans using conventional (limited to a few coplanar beams) radiation therapy. A preliminary study suggested two promising algorithms for restricting the number of beam weights. The purpose of this investigation was to compare these two algorithms using our current SA algorithm with the aim of producing a algorithm to allow clinically useful radiation therapy treatment planning optimization. Method: Our current SA algorithm, Variable Stepsize Generalized Simulated Annealing (VSGSA) was modified with two algorithms to restrict the number of beam weights in the final solution. The first algorithm selected combinations of a fixed number of beams from the complete solution space at each iterative step of the optimization process. The second reduced the allowed number of beams by a factor of two at periodic steps during the optimization process until only the specified number of beams remained. Results of optimization of beam weights and angles using these algorithms were compared using a standard cadre of abdominal cases. The solution space was defined as a set of 36 custom-shaped open and wedged-filtered fields at 10 deg. increments with a target constant target volume margin of 1.2 cm. For each case a clinically-accepted cost function, minimum tumor dose was maximized subject to a set of normal tissue binary dose-volume constraints. For this study, the optimized plan was restricted to four (4) fields suitable for delivery with conventional therapy equipment. Results: The table gives the mean value of the minimum target dose obtained for each algorithm averaged over 5 different runs and the comparable manual treatment

Inverse Kinematics With Closed Form Solution For Denso Robot Manipulator

Directory of Open Access Journals (Sweden)

Ikhsan Eka Prasetia

2015-03-01

Full Text Available In this paper, the forward kinematics and inverse kinematics used on the Denso robot manipulator which has a 6-DOF. The forward kinematics will result in the desired position by end-effector, while inverse kinematics produce angel on each joint. Inverse kinematics problem are very difficult, therefor to obtain the solution of inverse kinematics using closed form solution with geometry approach. The simulation result obtained from forward kinematics and inverse kinematics is determining desired position by Denso robot manipulator. Forward kinematics produce the desired position by the end-effector. Inverse kinematics produce joint angle, where the inverse kinematics produce eight conditions obtained from closed form solution with geometry approach to reach the desired position by the end-effector.

Particle simulations of nonlinear whistler and Alfven wave instabilities - Amplitude modulation, decay, soliton and inverse cascading

International Nuclear Information System (INIS)

Omura, Yoshiharu; Matsumoto, Hiroshi.

1989-01-01

Past theoretical and numerical studies of the nonlinear evolution of electromagnetic cyclotron waves are reviewed. Such waves are commonly observed in space plasmas such as Alfven waves in the solar wind or VLF whistler mode waves in the magnetosphere. The use of an electromagnetic full-particle code to study an electron cyclotron wave and of an electromagnetic hybrid code to study an ion cyclotron wave is demonstrated. Recent achievements in the simulations of nonlinear revolution of electromagnetic cyclotron waves are discussed. The inverse cascading processes of finite-amplitude whistler and Alfven waves is interpreted in terms of physical elementary processes. 65 refs

Simulation study of HEMT structures with HfO{sub 2} cap layer for mitigating inverse piezoelectric effect related device failures

Energy Technology Data Exchange (ETDEWEB)

Nagulapally, Deepthi; Joshi, Ravi P., E-mail: rjoshi@odu.edu [Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA 23529-0246 (United States); Pradhan, Aswini [Department of Engineering and Center for Materials Research, Norfolk State University, 700 Park Avenue, Norfolk, VA 23504 (United States)

2015-01-15

The Inverse Piezoelectric Effect (IPE) is thought to contribute to possible device failure of GaN High Electron Mobility Transistors (HEMTs). Here we focus on a simulation study to probe the possible mitigation of the IPE by reducing the internal electric fields and related elastic energy through the use of high-k materials. Inclusion of a HfO{sub 2} “cap layer” above the AlGaN barrier particularly with a partial mesa structure is shown to have potential advantages. Simulations reveal even greater reductions in the internal electric fields by using “field plates” in concert with high-k oxides.

Inverse Reliability Task: Artificial Neural Networks and Reliability-Based Optimization Approaches

OpenAIRE

Lehký , David; Slowik , Ondřej; Novák , Drahomír

2014-01-01

Part 7: Genetic Algorithms; International audience; The paper presents two alternative approaches to solve inverse reliability task – to determine the design parameters to achieve desired target reliabilities. The first approach is based on utilization of artificial neural networks and small-sample simulation Latin hypercube sampling. The second approach considers inverse reliability task as reliability-based optimization task using double-loop method and also small-sample simulation. Efficie...

Rapid processing of data based on high-performance algorithms for solving inverse problems and 3D-simulation of the tsunami and earthquakes

Science.gov (United States)

Marinin, I. V.; Kabanikhin, S. I.; Krivorotko, O. I.; Karas, A.; Khidasheli, D. G.

2012-04-01

We consider new techniques and methods for earthquake and tsunami related problems, particularly - inverse problems for the determination of tsunami source parameters, numerical simulation of long wave propagation in soil and water and tsunami risk estimations. In addition, we will touch upon the issue of database management and destruction scenario visualization. New approaches and strategies, as well as mathematical tools and software are to be shown. The long joint investigations by researchers of the Institute of Mathematical Geophysics and Computational Mathematics SB RAS and specialists from WAPMERR and Informap have produced special theoretical approaches, numerical methods, and software tsunami and earthquake modeling (modeling of propagation and run-up of tsunami waves on coastal areas), visualization, risk estimation of tsunami, and earthquakes. Algorithms are developed for the operational definition of the origin and forms of the tsunami source. The system TSS numerically simulates the source of tsunami and/or earthquakes and includes the possibility to solve the direct and the inverse problem. It becomes possible to involve advanced mathematical results to improve models and to increase the resolution of inverse problems. Via TSS one can construct maps of risks, the online scenario of disasters, estimation of potential damage to buildings and roads. One of the main tools for the numerical modeling is the finite volume method (FVM), which allows us to achieve stability with respect to possible input errors, as well as to achieve optimum computing speed. Our approach to the inverse problem of tsunami and earthquake determination is based on recent theoretical results concerning the Dirichlet problem for the wave equation. This problem is intrinsically ill-posed. We use the optimization approach to solve this problem and SVD-analysis to estimate the degree of ill-posedness and to find the quasi-solution. The software system we developed is intended to

Inverse kinematic control of LDUA and TWRMS

International Nuclear Information System (INIS)

Yih, T.C.; Burks, B.L.; Kwon, Dong-Soo

1995-01-01

A general inverse kinematic analysis is formulated particularly for the redundant Light Duty Utility Arm (LDUA) and Tank Waste Retrieval Manipulator System (TWRMS). The developed approach is applicable to the inverse kinematic simulation and control of LDUA, TWRMS, and other general robot manipulators. The 4 x 4 homogeneous Cylindrical coordinates-Bryant angles (C-B) notation is adopted to model LDUA, TWRMS, and any robot composed of R (revolute), P (prismatic), and/or S (spherical) joints

Development of a Searchable Database of Cryoablation Simulations for Use in Treatment Planning

Energy Technology Data Exchange (ETDEWEB)

Boas, F. Edward, E-mail: boasf@mskcc.org; Srimathveeravalli, Govindarajan, E-mail: srimaths@mskcc.org; Durack, Jeremy C., E-mail: durackj@mskcc.org [Memorial Sloan Kettering Cancer Center, Department of Radiology (United States); Kaye, Elena A., E-mail: kayee@mskcc.org [Memorial Sloan Kettering Cancer Center, Department of Medical Physics (United States); Erinjeri, Joseph P., E-mail: erinjerj@mskcc.org; Ziv, Etay, E-mail: zive@mskcc.org; Maybody, Majid, E-mail: maybodym@mskcc.org; Yarmohammadi, Hooman, E-mail: yarmohah@mskcc.org; Solomon, Stephen B., E-mail: solomons@mskcc.org [Memorial Sloan Kettering Cancer Center, Department of Radiology (United States)

2017-05-15

PurposeTo create and validate a planning tool for multiple-probe cryoablation, using simulations of ice ball size and shape for various ablation probe configurations, ablation times, and types of tissue ablated.Materials and MethodsIce ball size and shape was simulated using the Pennes bioheat equation. Five thousand six hundred and seventy different cryoablation procedures were simulated, using 1–6 cryoablation probes and 1–2 cm spacing between probes. The resulting ice ball was measured along three perpendicular axes and recorded in a database. Simulated ice ball sizes were compared to gel experiments (26 measurements) and clinical cryoablation cases (42 measurements). The clinical cryoablation measurements were obtained from a HIPAA-compliant retrospective review of kidney and liver cryoablation procedures between January 2015 and February 2016. Finally, we created a web-based cryoablation planning tool, which uses the cryoablation simulation database to look up the probe spacing and ablation time that produces the desired ice ball shape and dimensions.ResultsAverage absolute error between the simulated and experimentally measured ice balls was 1 mm in gel experiments and 4 mm in clinical cryoablation cases. The simulations accurately predicted the degree of synergy in multiple-probe ablations. The cryoablation simulation database covers a wide range of ice ball sizes and shapes up to 9.8 cm.ConclusionCryoablation simulations accurately predict the ice ball size in multiple-probe ablations. The cryoablation database can be used to plan ablation procedures: given the desired ice ball size and shape, it will find the number and type of probes, probe configuration and spacing, and ablation time required.

Development of a Searchable Database of Cryoablation Simulations for Use in Treatment Planning

International Nuclear Information System (INIS)

Boas, F. Edward; Srimathveeravalli, Govindarajan; Durack, Jeremy C.; Kaye, Elena A.; Erinjeri, Joseph P.; Ziv, Etay; Maybody, Majid; Yarmohammadi, Hooman; Solomon, Stephen B.

2017-01-01

PurposeTo create and validate a planning tool for multiple-probe cryoablation, using simulations of ice ball size and shape for various ablation probe configurations, ablation times, and types of tissue ablated.Materials and MethodsIce ball size and shape was simulated using the Pennes bioheat equation. Five thousand six hundred and seventy different cryoablation procedures were simulated, using 1–6 cryoablation probes and 1–2 cm spacing between probes. The resulting ice ball was measured along three perpendicular axes and recorded in a database. Simulated ice ball sizes were compared to gel experiments (26 measurements) and clinical cryoablation cases (42 measurements). The clinical cryoablation measurements were obtained from a HIPAA-compliant retrospective review of kidney and liver cryoablation procedures between January 2015 and February 2016. Finally, we created a web-based cryoablation planning tool, which uses the cryoablation simulation database to look up the probe spacing and ablation time that produces the desired ice ball shape and dimensions.ResultsAverage absolute error between the simulated and experimentally measured ice balls was 1 mm in gel experiments and 4 mm in clinical cryoablation cases. The simulations accurately predicted the degree of synergy in multiple-probe ablations. The cryoablation simulation database covers a wide range of ice ball sizes and shapes up to 9.8 cm.ConclusionCryoablation simulations accurately predict the ice ball size in multiple-probe ablations. The cryoablation database can be used to plan ablation procedures: given the desired ice ball size and shape, it will find the number and type of probes, probe configuration and spacing, and ablation time required.

New development of integrated CT simulation system for radiation therapy planning

International Nuclear Information System (INIS)

Kushima, Takeyuki; Kono, Michio

1993-01-01

In order to put more accurate radiotherapy into practice, a radiotherapy planning system using CT, which is named CT simulation system, has been developed and introduced at Kobe University Hospital. The CT simulation system consists of a CT scanner, an image processing work-station, and a laser marking system. The target area of radiation is determined on each CT axial image of scout view in the work-station. Three-dimensional treatment planning is feasible on the basis of the two-dimensional tumor information in CT axial images. After setting treatment parameters, the contour of the radiation field on beam's eye view and the iso-center position are calculated by computer. This system makes it possible to choose an appropriate irradiation method and an optimal dose distribution. In the present study we examined the fundamental capability of this system. The laser marking system proved to have a very high degree of accuracy. The outcome of a phantom test raised the strong possibility that this system may be applied clinically. In addition to these basic findings, this paper describes preliminary clinical observations that support the good reproducibility of the radiation field projected with the CT simulator. In conclusion, this system is of high value for radiation therapy planning. (author)

An Interprofessional Approach to Continuing Education With Mass Casualty Simulation: Planning and Execution.

Science.gov (United States)

Saber, Deborah A; Strout, Kelley; Caruso, Lisa Swanson; Ingwell-Spolan, Charlene; Koplovsky, Aiden

2017-10-01

Many natural and man-made disasters require the assistance from teams of health care professionals. Knowing that continuing education about disaster simulation training is essential to nursing students, nurses, and emergency first responders (e.g., emergency medical technicians, firefighters, police officers), a university in the northeastern United States planned and implemented an interprofessional mass casualty incident (MCI) disaster simulation using the Project Management Body of Knowledge (PMBOK) management framework. The school of nursing and University Volunteer Ambulance Corps (UVAC) worked together to simulate a bus crash with disaster victim actors to provide continued education for community first responders and train nursing students on the MCI process. This article explains the simulation activity, planning process, and achieved outcomes. J Contin Educ Nurs. 2017;48(10):447-453. Copyright 2017, SLACK Incorporated.

Improving multiple-point-based a priori models for inverse problems by combining Sequential Simulation with the Frequency Matching Method

DEFF Research Database (Denmark)

Cordua, Knud Skou; Hansen, Thomas Mejer; Lange, Katrine

In order to move beyond simplified covariance based a priori models, which are typically used for inverse problems, more complex multiple-point-based a priori models have to be considered. By means of marginal probability distributions ‘learned’ from a training image, sequential simulation has...... proven to be an efficient way of obtaining multiple realizations that honor the same multiple-point statistics as the training image. The frequency matching method provides an alternative way of formulating multiple-point-based a priori models. In this strategy the pattern frequency distributions (i.......e. marginals) of the training image and a subsurface model are matched in order to obtain a solution with the same multiple-point statistics as the training image. Sequential Gibbs sampling is a simulation strategy that provides an efficient way of applying sequential simulation based algorithms as a priori...

MRI-based treatment plan simulation and adaptation for ion radiotherapy using a classification-based approach

International Nuclear Information System (INIS)

Rank, Christopher M; Tremmel, Christoph; Hünemohr, Nora; Nagel, Armin M; Jäkel, Oliver; Greilich, Steffen

2013-01-01

In order to benefit from the highly conformal irradiation of tumors in ion radiotherapy, sophisticated treatment planning and simulation are required. The purpose of this study was to investigate the potential of MRI for ion radiotherapy treatment plan simulation and adaptation using a classification-based approach. Firstly, a voxelwise tissue classification was applied to derive pseudo CT numbers from MR images using up to 8 contrasts. Appropriate MR sequences and parameters were evaluated in cross-validation studies of three phantoms. Secondly, ion radiotherapy treatment plans were optimized using both MRI-based pseudo CT and reference CT and recalculated on reference CT. Finally, a target shift was simulated and a treatment plan adapted to the shift was optimized on a pseudo CT and compared to reference CT optimizations without plan adaptation. The derivation of pseudo CT values led to mean absolute errors in the range of 81 - 95 HU. Most significant deviations appeared at borders between air and different tissue classes and originated from partial volume effects. Simulations of ion radiotherapy treatment plans using pseudo CT for optimization revealed only small underdosages in distal regions of a target volume with deviations of the mean dose of PTV between 1.4 - 3.1% compared to reference CT optimizations. A plan adapted to the target volume shift and optimized on the pseudo CT exhibited a comparable target dose coverage as a non-adapted plan optimized on a reference CT. We were able to show that a MRI-based derivation of pseudo CT values using a purely statistical classification approach is feasible although no physical relationship exists. Large errors appeared at compact bone classes and came from an imperfect distinction of bones and other tissue types in MRI. In simulations of treatment plans, it was demonstrated that these deviations are comparable to uncertainties of a target volume shift of 2 mm in two directions indicating that especially

Investigation into the factors that influence inverse bulging effect during sheet hydro-mechanical deep drawing

Directory of Open Access Journals (Sweden)

Lang Lihui

2015-01-01

Full Text Available The factors that influence inverse bulging effect during sheet hydro-mechanical deep drawing are especially researched in this paper. According to the different inverse bulging process, two modes can be singled: the initial inverse bulging (IIB and the local inverse bulging (LIB. IIB includes two parameters: inverse bulging height ratio (HIb/t and inverse bulging pressure ratio (PIb/t. LIB is influenced by IIB and has a direct relationship with liquid chamber pressure in the forming process. The optimal inverse bulging parameters of hemispherical bottom cylindrical part and flat bottom cylindrical part are obtained by numerical simulation. Process parameters including the clearance between the punch and the blank holder and the blank holder entrance radius that have a large influence on inverse bulging effect are optimized, so as to make inverse bulging effect behave better in hydroforming process. Finally, the accuracy of the numerical simulation results was verified by experiments.

Identification of polymorphic inversions from genotypes

Directory of Open Access Journals (Sweden)

Cáceres Alejandro

2012-02-01

Full Text Available Abstract Background Polymorphic inversions are a source of genetic variability with a direct impact on recombination frequencies. Given the difficulty of their experimental study, computational methods have been developed to infer their existence in a large number of individuals using genome-wide data of nucleotide variation. Methods based on haplotype tagging of known inversions attempt to classify individuals as having a normal or inverted allele. Other methods that measure differences between linkage disequilibrium attempt to identify regions with inversions but unable to classify subjects accurately, an essential requirement for association studies. Results We present a novel method to both identify polymorphic inversions from genome-wide genotype data and classify individuals as containing a normal or inverted allele. Our method, a generalization of a published method for haplotype data 1, utilizes linkage between groups of SNPs to partition a set of individuals into normal and inverted subpopulations. We employ a sliding window scan to identify regions likely to have an inversion, and accumulation of evidence from neighboring SNPs is used to accurately determine the inversion status of each subject. Further, our approach detects inversions directly from genotype data, thus increasing its usability to current genome-wide association studies (GWAS. Conclusions We demonstrate the accuracy of our method to detect inversions and classify individuals on principled-simulated genotypes, produced by the evolution of an inversion event within a coalescent model 2. We applied our method to real genotype data from HapMap Phase III to characterize the inversion status of two known inversions within the regions 17q21 and 8p23 across 1184 individuals. Finally, we scan the full genomes of the European Origin (CEU and Yoruba (YRI HapMap samples. We find population-based evidence for 9 out of 15 well-established autosomic inversions, and for 52 regions

Inverse-FEM Characterization of a Brain Tissue Phantom to Simulate Compression and Indentation Caracterización de tejido cerebral artificial utilizando Inverse-FEM para simular indentación y comprensión

Directory of Open Access Journals (Sweden)

Elizabeth Mesa-Múnera

2012-12-01

Full Text Available The realistic simulation of tool-tissue interactions is necessary for the development of surgical simulators and one of the key element for it realism is accurate bio-mechanical tissue models. In this paper, we determined the mechanical properties of soft tissue by minimizing the difference between experimental measurements and the analytical or simulated solution of the deformation. Then, we selected the best model parameters that fit the experimental data to simulate a bonded compression and a needle indentation with a flat-tip. We show that the inverse FEM allows accurate material property estimation. We also validated our results using multiple tool-tissue interactions over the same specimen.Una simulación realista de la interacción tejido-herramienta es necesaria para desarrollar simuldores quirúrgicos, y la presición en modelos biomecánicos de tejidos es determinante para cumplir tal fin. Los trabajos previos han caracterizado las propiedades de tejidos blandos; sin embargo, ha faltado una validación apropiada de los resultados. En este trabajo se determinaron las propiedades mecánicas de un tejido blando minimizando la diferencia entre las mediciones experimentales y la solución analítica o simulada del problema. Luego, fueron seleccionados los parámetros que mejor se ajustaron a los datos experimentales para simular una compresión con fricción y la indentación de una aguja con punta plana. Se concluye que el inverse-FEM permite la precisa estimación de las propiedades del material. Además, estos resultados fueron validados con varias interacciones tejido-herramienta sobre el mismo espécimen.

A framework for inverse planning of beam-on times for 3D small animal radiotherapy using interactive multi-objective optimisation

International Nuclear Information System (INIS)

Balvert, Marleen; Den Hertog, Dick; Van Hoof, Stefan J; Granton, Patrick V; Trani, Daniela; Hoffmann, Aswin L; Verhaegen, Frank

2015-01-01

Advances in precision small animal radiotherapy hardware enable the delivery of increasingly complicated dose distributions on the millimeter scale. Manual creation and evaluation of treatment plans becomes difficult or even infeasible with an increasing number of degrees of freedom for dose delivery and available image data. The goal of this work is to develop an optimisation model that determines beam-on times for a given beam configuration, and to assess the feasibility and benefits of an automated treatment planning system for small animal radiotherapy.The developed model determines a Pareto optimal solution using operator-defined weights for a multiple-objective treatment planning problem. An interactive approach allows the planner to navigate towards, and to select the Pareto optimal treatment plan that yields the most preferred trade-off of the conflicting objectives. This model was evaluated using four small animal cases based on cone-beam computed tomography images. Resulting treatment plan quality was compared to the quality of manually optimised treatment plans using dose-volume histograms and metrics.Results show that the developed framework is well capable of optimising beam-on times for 3D dose distributions and offers several advantages over manual treatment plan optimisation. For all cases but the simple flank tumour case, a similar amount of time was needed for manual and automated beam-on time optimisation. In this time frame, manual optimisation generates a single treatment plan, while the inverse planning system yields a set of Pareto optimal solutions which provides quantitative insight on the sensitivity of conflicting objectives. Treatment planning automation decreases the dependence on operator experience and allows for the use of class solutions for similar treatment scenarios. This can shorten the time required for treatment planning and therefore increase animal throughput. In addition, this can improve treatment standardisation and

Optimal Acceleration-Velocity-Bounded Trajectory Planning in Dynamic Crowd Simulation

Directory of Open Access Journals (Sweden)

Fu Yue-wen

2014-01-01

Full Text Available Creating complex and realistic crowd behaviors, such as pedestrian navigation behavior with dynamic obstacles, is a difficult and time consuming task. In this paper, we study one special type of crowd which is composed of urgent individuals, normal individuals, and normal groups. We use three steps to construct the crowd simulation in dynamic environment. The first one is that the urgent individuals move forward along a given path around dynamic obstacles and other crowd members. An optimal acceleration-velocity-bounded trajectory planning method is utilized to model their behaviors, which ensures that the durations of the generated trajectories are minimal and the urgent individuals are collision-free with dynamic obstacles (e.g., dynamic vehicles. In the second step, a pushing model is adopted to simulate the interactions between urgent members and normal ones, which ensures that the computational cost of the optimal trajectory planning is acceptable. The third step is obligated to imitate the interactions among normal members using collision avoidance behavior and flocking behavior. Various simulation results demonstrate that these three steps give realistic crowd phenomenon just like the real world.

Improving Inversions of the Overlap Operator

International Nuclear Information System (INIS)

Krieg, S.; Cundy, N.; Eshof, J. van den; Frommer, A.; Lippert, Th.; Schaefer, K.

2005-01-01

We present relaxation and preconditioning techniques which accelerate the inversion of the overlap operator by a factor of four on small lattices, with larger gains as the lattice size increases. These improvements can be used in both propagator calculations and dynamical simulations

Patient dose simulation in X-ray CT using a radiation treatment-planning system

International Nuclear Information System (INIS)

Nakae, Yasuo; Oda, Masahiko; Minamoto, Takahiro

2003-01-01

Medical irradiation dosage has been increasing with the development of new radiological equipment and new techniques like interventional radiology. It is fair to say that patient dose has been increased as a result of the development of multi-slice CT. A number of studies on the irradiation dose of CT have been reported, and the computed tomography dose index (CTDI) is now used as a general means of determining CT dose. However, patient dose distribution in the body varies with the patient's constitution, bowel gas in the body, and conditions of exposure. In this study, patient dose was analyzed from the viewpoint of dose distribution, using a radiation treatment-planning computer. Percent depth dose (PDD) and the off-center ratio (OCR) of the CT beam are needed to calculate dose distribution by the planning computer. Therefore, X-ray CT data were measured with various apparatuses, and beam data were sent to the planning computer. Measurement and simulation doses in the elliptical phantom (Mix-Dp: water equivalent material) were collated, and the CT irradiation dose was determined for patient dose simulation. The rotational radiation treatment technique was used to obtain the patient dose distribution of CT, and patient dose was evaluated through simulation of the dose distribution. CT images of the thorax were sent to the planning computer and simulated. The result was that the patient dose distribution of the thorax was obtained for CT examination. (author)

Characterization of a Method for Inverse Heat Conduction Using Real and Simulated Thermocouple Data

Science.gov (United States)

Pizzo, Michelle E.; Glass, David E.

2017-01-01

It is often impractical to instrument the external surface of high-speed vehicles due to the aerothermodynamic heating. Temperatures can instead be measured internal to the structure using embedded thermocouples, and direct and inverse methods can then be used to estimate temperature and heat flux on the external surface. Two thermocouples embedded at different depths are required to solve direct and inverse problems, and filtering schemes are used to reduce noise in the measured data. Accuracy in the estimated surface temperature and heat flux is dependent on several factors. Factors include the thermocouple location through the thickness of a material, the sensitivity of the surface solution to the error in the specified location of the embedded thermocouples, and the sensitivity to the error in thermocouple data. The effect of these factors on solution accuracy is studied using the methodology discussed in the work of Pizzo, et. al.1 A numerical study is performed to determine if there is an optimal depth at which to embed one thermocouple through the thickness of a material assuming that a second thermocouple is installed on the back face. Solution accuracy will be discussed for a range of embedded thermocouple depths. Moreover, the sensitivity of the surface solution to (a) the error in the specified location of the embedded thermocouple and to (b) the error in the thermocouple data are quantified using numerical simulation, and the results are discussed.

The Source Inversion Validation (SIV) Initiative: A Collaborative Study on Uncertainty Quantification in Earthquake Source Inversions

Science.gov (United States)

Mai, P. M.; Schorlemmer, D.; Page, M.

2012-04-01

Earthquake source inversions image the spatio-temporal rupture evolution on one or more fault planes using seismic and/or geodetic data. Such studies are critically important for earthquake seismology in general, and for advancing seismic hazard analysis in particular, as they reveal earthquake source complexity and help (i) to investigate earthquake mechanics; (ii) to develop spontaneous dynamic rupture models; (iii) to build models for generating rupture realizations for ground-motion simulations. In applications (i - iii), the underlying finite-fault source models are regarded as "data" (input information), but their uncertainties are essentially unknown. After all, source models are obtained from solving an inherently ill-posed inverse problem to which many a priori assumptions and uncertain observations are applied. The Source Inversion Validation (SIV) project is a collaborative effort to better understand the variability between rupture models for a single earthquake (as manifested in the finite-source rupture model database) and to develop robust uncertainty quantification for earthquake source inversions. The SIV project highlights the need to develop a long-standing and rigorous testing platform to examine the current state-of-the-art in earthquake source inversion, and to develop and test novel source inversion approaches. We will review the current status of the SIV project, and report the findings and conclusions of the recent workshops. We will briefly discuss several source-inversion methods, how they treat uncertainties in data, and assess the posterior model uncertainty. Case studies include initial forward-modeling tests on Green's function calculations, and inversion results for synthetic data from spontaneous dynamic crack-like strike-slip earthquake on steeply dipping fault, embedded in a layered crustal velocity-density structure.

A Neural Network Combined Inverse Controller for a Two-Rear-Wheel Independently Driven Electric Vehicle

Directory of Open Access Journals (Sweden)

Duo Zhang

2014-07-01

Full Text Available Vehicle active safety control is attracting ever increasing attention in the attempt to improve the stability and the maneuverability of electric vehicles. In this paper, a neural network combined inverse (NNCI controller is proposed, incorporating the merits of left-inversion and right-inversion. As the left-inversion soft-sensor can estimate the sideslip angle, while the right-inversion is utilized to decouple control. Then, the proposed NNCI controller not only linearizes and decouples the original nonlinear system, but also directly obtains immeasurable state feedback in constructing the right-inversion. Hence, the proposed controller is very practical in engineering applications. The proposed system is co-simulated based on the vehicle simulation package CarSim in connection with Matlab/Simulink. The results verify the effectiveness of the proposed control strategy.

Simulation of 3D-treatment plans in head and neck tumors aided by matching of digitally reconstructed radiographs (DRR) and on-line distortion corrected simulator images

International Nuclear Information System (INIS)

Lohr, Frank; Schramm, Oliver; Schraube, Peter; Sroka-Perez, Gabriele; Seeber, Steffen; Schlepple, Gerd; Schlegel, Wolfgang; Wannenmacher, Michael

1997-01-01

Background and purpose: Simulation of 3D-treatment plans for head and neck malignancy is difficult due to complex anatomy. Therefore, CT-simulation and stereotactic techniques are becoming more common in the treatment preparation, overcoming the need for simulation. However, if simulation is still performed, it is an important step in the treatment preparation/execution chain, since simulation errors, if not detected immediately, can compromise the success of treatment. A recently developed PC-based system for on-line image matching and comparison of digitally reconstructed radiographs (DRR) and distortion corrected simulator monitor images that enables instant correction of field placement errors during the simulation process was evaluated. The range of field placement errors with noncomputer aided simulation is reported. Materials and methods: For 14 patients either a primary 3D-treatment plan or a 3D-boost plan after initial treatment with opposing laterals for head and neck malignancy with a coplanar or non-coplanar two- or three-field technique was simulated. After determining the robustness of the matching process and the accuracy of field placement error detection with phantom measurements, DRRs were generated from the treatment planning CT-dataset of each patient and were interactively matched with on-line simulator images that had undergone correction for geometrical distortion, using a landmark algorithm. Translational field placement errors in all three planes as well as in-plane rotational errors were studied and were corrected immediately. Results: The interactive matching process is very robust with a tolerance of <2 mm when suitable anatomical landmarks are chosen. The accuracy for detection of translational errors in phantom measurements was <1 mm and for in-plane rotational errors the accuracy had a maximum of only 1.5 deg.. For patient simulation, the mean absolute distance of the planned versus simulated isocenter was 6.4 ± 3.9 mm. The in

Inverse kinematic-based robot control

Science.gov (United States)

Wolovich, W. A.; Flueckiger, K. F.

1987-01-01

A fundamental problem which must be resolved in virtually all non-trivial robotic operations is the well-known inverse kinematic question. More specifically, most of the tasks which robots are called upon to perform are specified in Cartesian (x,y,z) space, such as simple tracking along one or more straight line paths or following a specified surfacer with compliant force sensors and/or visual feedback. In all cases, control is actually implemented through coordinated motion of the various links which comprise the manipulator; i.e., in link space. As a consequence, the control computer of every sophisticated anthropomorphic robot must contain provisions for solving the inverse kinematic problem which, in the case of simple, non-redundant position control, involves the determination of the first three link angles, theta sub 1, theta sub 2, and theta sub 3, which produce a desired wrist origin position P sub xw, P sub yw, and P sub zw at the end of link 3 relative to some fixed base frame. Researchers outline a new inverse kinematic solution and demonstrate its potential via some recent computer simulations. They also compare it to current inverse kinematic methods and outline some of the remaining problems which will be addressed in order to render it fully operational. Also discussed are a number of practical consequences of this technique beyond its obvious use in solving the inverse kinematic question.

Strategic planning for skills and simulation labs in colleges of nursing.

Science.gov (United States)

Gantt, Laura T

2010-01-01

While simulation laboratories for clinical nursing education are predicted to grow, budget cuts may threaten these programs. One of the ways to develop a new lab, as well as to keep an existing one on track, is to develop and regularly update a strategic plan. The process of planning not only helps keep the lab faculty and staff apprised of the challenges to be faced, but it also helps to keep senior level management engaged by reason of the need for their input and approval of the plan. The strategic planning documents drafted by those who supervised the development of the new building and Concepts Integration Labs (CILs) helped guide and orient faculty and other personnel hired to implement the plan and fulfill the vision. As the CILs strategic plan was formalized, the draft plans, including the SWOT analysis, were reviewed to provide historical perspective, stimulate discussion, and to make sure old or potential mistakes were not repeated.

Monte-Carlo simulation of a high-resolution inverse geometry spectrometer on the SNS. Long Wavelength Target Station

International Nuclear Information System (INIS)

Bordallo, H.N.; Herwig, K.W.

2001-01-01

Using the Monte-Carlo simulation program McStas, we present the design principles of the proposed high-resolution inverse geometry spectrometer on the SNS-Long Wavelength Target Station (LWTS). The LWTS will provide the high flux of long wavelength neutrons at the requisite pulse rate required by the spectrometer design. The resolution of this spectrometer lies between that routinely achieved by spin echo techniques and the design goal of the high power target station backscattering spectrometer. Covering this niche in energy resolution will allow systematic studies over the large dynamic range required by many disciplines, such as protein dynamics. (author)

Creating virtual humans for simulation-based training and planning

Energy Technology Data Exchange (ETDEWEB)

Stansfield, S.; Sobel, A.

1998-05-12

Sandia National Laboratories has developed a distributed, high fidelity simulation system for training and planning small team Operations. The system provides an immersive environment populated by virtual objects and humans capable of displaying complex behaviors. The work has focused on developing the behaviors required to carry out complex tasks and decision making under stress. Central to this work are techniques for creating behaviors for virtual humans and for dynamically assigning behaviors to CGF to allow scenarios without fixed outcomes. Two prototype systems have been developed that illustrate these capabilities: MediSim, a trainer for battlefield medics and VRaptor, a system for planning, rehearsing and training assault operations.

Atmospheric inverse modeling via sparse reconstruction

Science.gov (United States)

Hase, Nils; Miller, Scot M.; Maaß, Peter; Notholt, Justus; Palm, Mathias; Warneke, Thorsten

2017-10-01

Many applications in atmospheric science involve ill-posed inverse problems. A crucial component of many inverse problems is the proper formulation of a priori knowledge about the unknown parameters. In most cases, this knowledge is expressed as a Gaussian prior. This formulation often performs well at capturing smoothed, large-scale processes but is often ill equipped to capture localized structures like large point sources or localized hot spots. Over the last decade, scientists from a diverse array of applied mathematics and engineering fields have developed sparse reconstruction techniques to identify localized structures. In this study, we present a new regularization approach for ill-posed inverse problems in atmospheric science. It is based on Tikhonov regularization with sparsity constraint and allows bounds on the parameters. We enforce sparsity using a dictionary representation system. We analyze its performance in an atmospheric inverse modeling scenario by estimating anthropogenic US methane (CH4) emissions from simulated atmospheric measurements. Different measures indicate that our sparse reconstruction approach is better able to capture large point sources or localized hot spots than other methods commonly used in atmospheric inversions. It captures the overall signal equally well but adds details on the grid scale. This feature can be of value for any inverse problem with point or spatially discrete sources. We show an example for source estimation of synthetic methane emissions from the Barnett shale formation.

Mantle conductivity obtained by 3-D inversion of magnetic satellite data

DEFF Research Database (Denmark)

Kuvshinov, A.; Olsen, Nils

distributed geomagnetic observatories. Due to the high computational load of a 3-D inversion (requiring thousands of forward calculations), a comprehensive numerical framework is developed to increase the efficiency of the inversion.In particular, we take an advantage of specific features of the IE approach...... and perform the most consuming-time part of the IE forward simulations (the calculation of electric and magnetic tensor Green’s functions) only once. Approximate calculation of the data sensitivities also gives essential speed up of the inversion. We validate our inversion scheme using synthetic induction...

Algorithm for planning a double-jaw orthognathic surgery using a computer-aided surgical simulation (CASS) protocol. Part 1: planning sequence

Science.gov (United States)

Xia, J. J.; Gateno, J.; Teichgraeber, J. F.; Yuan, P.; Chen, K.-C.; Li, J.; Zhang, X.; Tang, Z.; Alfi, D. M.

2015-01-01

The success of craniomaxillofacial (CMF) surgery depends not only on the surgical techniques, but also on an accurate surgical plan. The adoption of computer-aided surgical simulation (CASS) has created a paradigm shift in surgical planning. However, planning an orthognathic operation using CASS differs fundamentally from planning using traditional methods. With this in mind, the Surgical Planning Laboratory of Houston Methodist Research Institute has developed a CASS protocol designed specifically for orthognathic surgery. The purpose of this article is to present an algorithm using virtual tools for planning a double-jaw orthognathic operation. This paper will serve as an operation manual for surgeons wanting to incorporate CASS into their clinical practice. PMID:26573562

Influence of seeing effects on cloud model inversions

Czech Academy of Sciences Publication Activity Database

Tziotziou, K.; Heinzel, Petr; Tsiropoula, G.

2007-01-01

Roč. 472, č. 1 (2007), s. 287-292 ISSN 0004-6361 Institutional research plan: CEZ:AV0Z10030501 Keywords : cloud model * inversions * seeing effects Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.259, year: 2007

Nonlinear problems in fluid dynamics and inverse scattering: Nonlinear waves and inverse scattering

Science.gov (United States)

Ablowitz, Mark J.

1994-12-01

Research investigations involving the fundamental understanding and applications of nonlinear wave motion and related studies of inverse scattering and numerical computation have been carried out and a number of significant results have been obtained. A class of nonlinear wave equations which can be solved by the inverse scattering transform (IST) have been studied, including the Kadaomtsev-Petviashvili (KP) equation, the Davey-Stewartson equation, and the 2+1 Toda system. The solutions obtained by IST correspond to the Cauchy initial value problem with decaying initial data. We have also solved two important systems via the IST method: a 'Volterra' system in 2+1 dimensions and a new one dimensional nonlinear equation which we refer to as the Toda differential-delay equation. Research in computational chaos in moderate to long time numerical simulations continues.

An R Package for a General Class of Inverse Gaussian Distributions

Directory of Open Access Journals (Sweden)

Victor Leiva

2007-03-01

Full Text Available The inverse Gaussian distribution is a positively skewed probability model that has received great attention in the last 20 years. Recently, a family that generalizes this model called inverse Gaussian type distributions has been developed. The new R package named ig has been designed to analyze data from inverse Gaussian type distributions. This package contains basic probabilistic functions, lifetime indicators and a random number generator from this model. Also, parameter estimates and diagnostics analysis can be obtained using likelihood methods by means of this package. In addition, goodness-of-fit methods are implemented in order to detect the suitability of the model to the data. The capabilities and features of the ig package are illustrated using simulated and real data sets. Furthermore, some new results related to the inverse Gaussian type distribution are also obtained. Moreover, a simulation study is conducted for evaluating the estimation method implemented in the ig package.

Laterally constrained inversion for CSAMT data interpretation

Science.gov (United States)

Wang, Ruo; Yin, Changchun; Wang, Miaoyue; Di, Qingyun

2015-10-01

Laterally constrained inversion (LCI) has been successfully applied to the inversion of dc resistivity, TEM and airborne EM data. However, it hasn't been yet applied to the interpretation of controlled-source audio-frequency magnetotelluric (CSAMT) data. In this paper, we apply the LCI method for CSAMT data inversion by preconditioning the Jacobian matrix. We apply a weighting matrix to Jacobian to balance the sensitivity of model parameters, so that the resolution with respect to different model parameters becomes more uniform. Numerical experiments confirm that this can improve the convergence of the inversion. We first invert a synthetic dataset with and without noise to investigate the effect of LCI applications to CSAMT data, for the noise free data, the results show that the LCI method can recover the true model better compared to the traditional single-station inversion; and for the noisy data, the true model is recovered even with a noise level of 8%, indicating that LCI inversions are to some extent noise insensitive. Then, we re-invert two CSAMT datasets collected respectively in a watershed and a coal mine area in Northern China and compare our results with those from previous inversions. The comparison with the previous inversion in a coal mine shows that LCI method delivers smoother layer interfaces that well correlate to seismic data, while comparison with a global searching algorithm of simulated annealing (SA) in a watershed shows that though both methods deliver very similar good results, however, LCI algorithm presented in this paper runs much faster. The inversion results for the coal mine CSAMT survey show that a conductive water-bearing zone that was not revealed by the previous inversions has been identified by the LCI. This further demonstrates that the method presented in this paper works for CSAMT data inversion.

Refraction traveltime tomography with irregular topography using the unwrapped phase inversion

KAUST Repository

Choi, Yun Seok

2013-01-01

Traveltime tomography has long served as a stable and efficient tool for velocity estimation, especially for the near surface. It, however, suffers from some of limitations associated with ray tracing and high-frequency traveltime in velocity inversion zones and ray shadow regions. We develop a tomographic approach based on traveltime solutions obtained by tracking the phase (instantaneous traveltime) of the wavefield solution of the Helmholtz wave equation. Since the instantaneous-traveltime does not suffer from phase wrapping, the inversion algorithm using the instantaneous-traveltime has the potential to generate robust inversion results. With a high damping factor, the instantaneous-traveltime inversion provides refraction tomography similar results, but from a single frequency. Despite the Helmholtz-based solver implementation, the tomographic inversion handles irrgular topography. The numerical examples show that our inversion algorithm generates a convergent smooth velocity model, which looks very much like a tomographic result. Next, we plan to apply the instantaneous-traveltime inversion algorithm to real seismic data acquired from the near surface with irregular topography.

3D stochastic inversion and joint inversion of potential fields for multi scale parameters

Science.gov (United States)

Shamsipour, Pejman

In this thesis we present the development of new techniques for the interpretation of potential field (gravity and magnetic data), which are the most widespread economic geophysical methods used for oil and mineral exploration. These new techniques help to address the long-standing issue with the interpretation of potential fields, namely the intrinsic non-uniqueness inversion of these types of data. The thesis takes the form of three papers (four including Appendix), which have been published, or soon to be published, in respected international journals. The purpose of the thesis is to introduce new methods based on 3D stochastical approaches for: 1) Inversion of potential field data (magnetic), 2) Multiscale Inversion using surface and borehole data and 3) Joint inversion of geophysical potential field data. We first present a stochastic inversion method based on a geostatistical approach to recover 3D susceptibility models from magnetic data. The aim of applying geostatistics is to provide quantitative descriptions of natural variables distributed in space or in time and space. We evaluate the uncertainty on the parameter model by using geostatistical unconditional simulations. The realizations are post-conditioned by cokriging to observation data. In order to avoid the natural tendency of the estimated structure to lay near the surface, depth weighting is included in the cokriging system. Then, we introduce algorithm for multiscale inversion, the presented algorithm has the capability of inverting data on multiple supports. The method involves four main steps: i. upscaling of borehole parameters (It could be density or susceptibility) to block parameters, ii. selection of block to use as constraints based on a threshold on kriging variance, iii. inversion of observation data with selected block densities as constraints, and iv. downscaling of inverted parameters to small prisms. Two modes of application are presented: estimation and simulation. Finally, a novel

CMOS/SOS RAM transient radiation upset and ''inversion'' effect investigation

International Nuclear Information System (INIS)

Nikiforov, A.Y.; Poljakov, I.V.

1996-01-01

The Complementary Metal-Oxide-Semiconductor/Silicon-on-Sapphire Random Access Memory (CMOS/SOS RAM) transient upset and inversion effect were investigated with pulsed laser, pulsed voltage generator and low-intensity light simulators. It was found that the inversion of information occurs due to memory cell photocurrents simultaneously with the power supply voltage drop transfer to memory cells outputs

Modeling, simulation, and optimal initiation planning for needle insertion into the liver.

Science.gov (United States)

Sharifi Sedeh, R; Ahmadian, M T; Janabi-Sharifi, F

2010-04-01

Needle insertion simulation and planning systems (SPSs) will play an important role in diminishing inappropriate insertions into soft tissues and resultant complications. Difficulties in SPS development are due in large part to the computational requirements of the extensive calculations in finite element (FE) models of tissue. For clinical feasibility, the computational speed of SPSs must be improved. At the same time, a realistic model of tissue properties that reflects large and velocity-dependent deformations must be employed. The purpose of this study is to address the aforementioned difficulties by presenting a cost-effective SPS platform for needle insertions into the liver. The study was constrained to planar (2D) cases, but can be extended to 3D insertions. To accommodate large and velocity-dependent deformations, a hyperviscoelastic model was devised to produce an FE model of liver tissue. Material constants were identified by a genetic algorithm applied to the experimental results of unconfined compressions of bovine liver. The approach for SPS involves B-spline interpolations of sample data generated from the FE model of liver. Two interpolation-based models are introduced to approximate puncture times and to approximate the coordinates of FE model nodes interacting with the needle tip as a function of the needle initiation pose; the latter was also a function of postpuncture time. A real-time simulation framework is provided, and its computational benefit is highlighted by comparing its performance with the FE method. A planning algorithm for optimal needle initiation was designed, and its effectiveness was evaluated by analyzing its accuracy in reaching a random set of targets at different resolutions of sampled data using the FE model. The proposed simulation framework can easily surpass haptic rates (>500 Hz), even with a high pose resolution level ( approximately 30). The computational time required to update the coordinates of the node at the

High effective inverse dynamics modelling for dual-arm robot

Science.gov (United States)

Shen, Haoyu; Liu, Yanli; Wu, Hongtao

2018-05-01

To deal with the problem of inverse dynamics modelling for dual arm robot, a recursive inverse dynamics modelling method based on decoupled natural orthogonal complement is presented. In this model, the concepts and methods of Decoupled Natural Orthogonal Complement matrices are used to eliminate the constraint forces in the Newton-Euler kinematic equations, and the screws is used to express the kinematic and dynamics variables. On this basis, the paper has developed a special simulation program with symbol software of Mathematica and conducted a simulation research on the a dual-arm robot. Simulation results show that the proposed method based on decoupled natural orthogonal complement can save an enormous amount of CPU time that was spent in computing compared with the recursive Newton-Euler kinematic equations and the results is correct and reasonable, which can verify the reliability and efficiency of the method.

Treatment planning for a small animal using Monte Carlo simulation

International Nuclear Information System (INIS)

Chow, James C. L.; Leung, Michael K. K.

2007-01-01

The development of a small animal model for radiotherapy research requires a complete setup of customized imaging equipment, irradiators, and planning software that matches the sizes of the subjects. The purpose of this study is to develop and demonstrate the use of a flexible in-house research environment for treatment planning on small animals. The software package, called DOSCTP, provides a user-friendly platform for DICOM computed tomography-based Monte Carlo dose calculation using the EGSnrcMP-based DOSXYZnrc code. Validation of the treatment planning was performed by comparing the dose distributions for simple photon beam geometries calculated through the Pinnacle3 treatment planning system and measurements. A treatment plan for a mouse based on a CT image set by a 360-deg photon arc is demonstrated. It is shown that it is possible to create 3D conformal treatment plans for small animals with consideration of inhomogeneities using small photon beam field sizes in the diameter range of 0.5-5 cm, with conformal dose covering the target volume while sparing the surrounding critical tissue. It is also found that Monte Carlo simulation is suitable to carry out treatment planning dose calculation for small animal anatomy with voxel size about one order of magnitude smaller than that of the human

Ultrasonic simulation - Imagine3D and SimScan: Tools to solve the inverse problem for complex turbine components

International Nuclear Information System (INIS)

Mair, H.D.; Ciorau, P.; Owen, D.; Hazelton, T.; Dunning, G.

2000-01-01

Two ultrasonic simulation packages: Imagine 3D and SIMSCAN have specifically been developed to solve the inverse problem for blade root and rotor steeple of low-pressure turbine. The software was integrated with the 3D drawing of the inspected parts, and with the dimensions of linear phased-array probes. SIMSCAN simulates the inspection scenario in both optional conditions: defect location and probe movement/refracted angle range. The results are displayed into Imagine 3-D, with a variety of options: rendering, display 1:1, grid, generated UT beam. The results are very useful for procedure developer, training and to optimize the phased-array probe inspection sequence. A spreadsheet is generated to correlate the defect coordinates with UT data (probe position, skew and refracted angle, UT path, and probe movement). The simulation models were validated during experimental work with phased-array systems. The accuracy in probe position is ±1 mm, and the refracted/skew angle is within ±0.5 deg. . Representative examples of phased array focal laws/probe movement for a specific defect location, are also included

Estimating tectonic history through basin simulation-enhanced seismic inversion: Geoinformatics for sedimentary basins

Science.gov (United States)

Tandon, K.; Tuncay, K.; Hubbard, K.; Comer, J.; Ortoleva, P.

2004-01-01

A data assimilation approach is demonstrated whereby seismic inversion is both automated and enhanced using a comprehensive numerical sedimentary basin simulator to study the physics and chemistry of sedimentary basin processes in response to geothermal gradient in much greater detail than previously attempted. The approach not only reduces costs by integrating the basin analysis and seismic inversion activities to understand the sedimentary basin evolution with respect to geodynamic parameters-but the technique also has the potential for serving as a geoinfomatics platform for understanding various physical and chemical processes operating at different scales within a sedimentary basin. Tectonic history has a first-order effect on the physical and chemical processes that govern the evolution of sedimentary basins. We demonstrate how such tectonic parameters may be estimated by minimizing the difference between observed seismic reflection data and synthetic ones constructed from the output of a reaction, transport, mechanical (RTM) basin model. We demonstrate the method by reconstructing the geothermal gradient. As thermal history strongly affects the rate of RTM processes operating in a sedimentary basin, variations in geothermal gradient history alter the present-day fluid pressure, effective stress, porosity, fracture statistics and hydrocarbon distribution. All these properties, in turn, affect the mechanical wave velocity and sediment density profiles for a sedimentary basin. The present-day state of the sedimentary basin is imaged by reflection seismology data to a high degree of resolution, but it does not give any indication of the processes that contributed to the evolution of the basin or causes for heterogeneities within the basin that are being imaged. Using texture and fluid properties predicted by our Basin RTM simulator, we generate synthetic seismograms. Linear correlation using power spectra as an error measure and an efficient quadratic

Ultrafast magnetic vortex core switching driven by the topological inverse Faraday effect.

Science.gov (United States)

Taguchi, Katsuhisa; Ohe, Jun-ichiro; Tatara, Gen

2012-09-21

We present a theoretical discovery of an unconventional mechanism of inverse Faraday effect which acts selectively on topological magnetic structures. The effect, topological inverse Faraday effect, is induced by the spin Berry's phase of the magnetic structure when a circularly polarized light is applied. Thus a spin-orbit interaction is not necessary unlike that in the conventional inverse Faraday effect. We demonstrate by numerical simulation that topological inverse Faraday effect realizes ultrafast switching of a magnetic vortex within a switching time of 150 ps without magnetic field.

Structural level set inversion for microwave breast screening

International Nuclear Information System (INIS)

Irishina, Natalia; Álvarez, Diego; Dorn, Oliver; Moscoso, Miguel

2010-01-01

We present a new inversion strategy for the early detection of breast cancer from microwave data which is based on a new multiphase level set technique. This novel structural inversion method uses a modification of the color level set technique adapted to the specific situation of structural breast imaging taking into account the high complexity of the breast tissue. We only use data of a few microwave frequencies for detecting the tumors hidden in this complex structure. Three level set functions are employed for describing four different types of breast tissue, where each of these four regions is allowed to have a complicated topology and to have an interior structure which needs to be estimated from the data simultaneously with the region interfaces. The algorithm consists of several stages of increasing complexity. In each stage more details about the anatomical structure of the breast interior is incorporated into the inversion model. The synthetic breast models which are used for creating simulated data are based on real MRI images of the breast and are therefore quite realistic. Our results demonstrate the potential and feasibility of the proposed level set technique for detecting, locating and characterizing a small tumor in its early stage of development embedded in such a realistic breast model. Both the data acquisition simulation and the inversion are carried out in 2D

CT-Based Brachytherapy Treatment Planning using Monte Carlo Simulation Aided by an Interface Software

Directory of Open Access Journals (Sweden)

Vahid Moslemi

2011-03-01

Full Text Available Introduction: In brachytherapy, radioactive sources are placed close to the tumor, therefore, small changes in their positions can cause large changes in the dose distribution. This emphasizes the need for computerized treatment planning. The usual method for treatment planning of cervix brachytherapy uses conventional radiographs in the Manchester system. Nowadays, because of their advantages in locating the source positions and the surrounding tissues, CT and MRI images are replacing conventional radiographs. In this study, we used CT images in Monte Carlo based dose calculation for brachytherapy treatment planning, using an interface software to create the geometry file required in the MCNP code. The aim of using the interface software is to facilitate and speed up the geometry set-up for simulations based on the patient’s anatomy. This paper examines the feasibility of this method in cervix brachytherapy and assesses its accuracy and speed. Material and Methods: For dosimetric measurements regarding the treatment plan, a pelvic phantom was made from polyethylene in which the treatment applicators could be placed. For simulations using CT images, the phantom was scanned at 120 kVp. Using an interface software written in MATLAB, the CT images were converted into MCNP input file and the simulation was then performed. Results: Using the interface software, preparation time for the simulations of the applicator and surrounding structures was approximately 3 minutes; the corresponding time needed in the conventional MCNP geometry entry being approximately 1 hour. The discrepancy in the simulated and measured doses to point A was 1.7% of the prescribed dose.  The corresponding dose differences between the two methods in rectum and bladder were 3.0% and 3.7% of the prescribed dose, respectively. Comparing the results of simulation using the interface software with those of simulation using the standard MCNP geometry entry showed a less than 1

Seismic stochastic inversion identify river channel sand body

Science.gov (United States)

He, Z.

2015-12-01

The technology of seismic inversion is regarded as one of the most important part of geophysics. By using the technology of seismic inversion and the theory of stochastic simulation, the concept of seismic stochastic inversion is proposed.Seismic stochastic inversion can play an significant role in the identifying river channel sand body. Accurate sand body description is a crucial parameter to measure oilfield development and oilfield stimulation during the middle and later periods. Besides, rational well spacing density is an essential condition for efficient production. Based on the geological knowledge of a certain oilfield, in line with the use of seismic stochastic inversion, the river channel sand body in the work area is identified. In this paper, firstly, the single river channel body from the composite river channel body is subdivided. Secondly, the distribution of river channel body is ascertained in order to ascertain the direction of rivers. Morever, the superimposed relationship among the sand body is analyzed, especially among the inter-well sand body. The last but not at the least, via the analysis of inversion results of first vacuating the wells and continuous infilling later, it is meeted the most needs well spacing density that can obtain the optimal inversion result. It would serve effective guidance for oilfield stimulation.

Enhancement of the Number of Fast Electrons Generated in a Laser Inverse Cone Interaction

International Nuclear Information System (INIS)

Yan-Ling, Ji; Gang, Jiang; Wei-Dong, Wu; Ji-Cheng, Zhang; Yong-Jian, Tang

2010-01-01

Enhancement of the energy-conversion efficiency from laser to target electrons is demonstrated by two-dimensional particle-in-cell simulations in a laser-inverse cone interaction. When an intense short-pulse laser illuminates the inverse cone target, the electrons at the cone end are accelerated by the ponderomotive force. Then these electrons are guided and confined to transport along the inverse cone walls by the induced electromagnetic fields. A device consisting of inverse hollow-cone and multihole array plasma is proposed in order to increase the energy-conversion efficiency from laser to electrons. Particle-in-cell simulations present that the multiholes transpiercing the cone end help to enhance the number of fast electrons and the maximum electron energy significantly. (physics of gases, plasmas, and electric discharges)

On the inverse transfer of (non-)helical magnetic energy in a decaying magnetohydrodynamic turbulence

Science.gov (United States)

Park, Kiwan

2017-12-01

In our conventional understanding, large-scale magnetic fields are thought to originate from an inverse cascade in the presence of magnetic helicity, differential rotation or a magneto-rotational instability. However, as recent simulations have given strong indications that an inverse cascade (transfer) may occur even in the absence of magnetic helicity, the physical origin of this inverse cascade is still not fully understood. We here present two simulations of freely decaying helical and non-helical magnetohydrodynamic (MHD) turbulence. We verified the inverse transfer of helical and non-helical magnetic fields in both cases, but we found the underlying physical principles to be fundamentally different. In the former case, the helical magnetic component leads to an inverse cascade of magnetic energy. We derived a semi-analytic formula for the evolution of large-scale magnetic field using α coefficient and compared it with the simulation data. But in the latter case, the α effect, including other conventional dynamo theories, is not suitable to describe the inverse transfer of non-helical magnetic energy. To obtain a better understanding of the physics at work here, we introduced a 'field structure model' based on the magnetic induction equation in the presence of inhomogeneities. This model illustrates how the curl of the electromotive force leads to the build up of a large-scale magnetic field without the requirement of magnetic helicity. And we applied a quasi-normal approximation to the inverse transfer of magnetic energy.

Inverse problem of solar oscillations

International Nuclear Information System (INIS)

Sekii, T.; Shibahashi, H.

1987-01-01

The authors present some preliminary results of numerical simulation to infer the sound velocity distribution in the solar interior from the oscillation data of the Sun as the inverse problem. They analyze the acoustic potential itself by taking account of some factors other than the sound velocity, and infer the sound velocity distribution in the deep interior of the Sun

Proportional Derivative Control with Inverse Dead-Zone for Pendulum Systems

Directory of Open Access Journals (Sweden)

José de Jesús Rubio

2013-01-01

Full Text Available A proportional derivative controller with inverse dead-zone is proposed for the control of pendulum systems. The proposed method has the characteristic that the inverse dead-zone is cancelled with the pendulum dead-zone. Asymptotic stability of the proposed technique is guaranteed by the Lyapunov analysis. Simulations of two pendulum systems show the effectiveness of the proposed technique.

Loading pattern calculated by inverse optimization vs traditional dosimetry systems of intracavitary brachytherapy of cervical cancer: a dosimetric study

International Nuclear Information System (INIS)

Jamema, S.V.; Deshpande, D.D.; Kirisits, C.; Trnkova, P.; Poetter, R.; Mahantshetty, U.; Shrivastava, S.K.; Dinshaw, K.A.

2008-01-01

In the recent past, inverse planning algorithms were introduced for intracavitary brachytherapy planning (ICBT) for cervical cancer. The loading pattern of these algorithms in comparison with traditional systems may not be similar. The purpose of this study was to objectively compare the loading patterns of traditional systems with the inverse optimization. Based on the outcome of the comparison, an attempt was made to obtain a loading pattern that takes into account the experience made with the inverse optimization

Analysis of the variability in ground-motion synthesis and inversion

Science.gov (United States)

Spudich, Paul A.; Cirella, Antonella; Scognamiglio, Laura; Tinti, Elisa

2017-12-07

In almost all past inversions of large-earthquake ground motions for rupture behavior, the goal of the inversion is to find the “best fitting” rupture model that predicts ground motions which optimize some function of the difference between predicted and observed ground motions. This type of inversion was pioneered in the linear-inverse sense by Olson and Apsel (1982), who minimized the square of the difference between observed and simulated motions (“least squares”) while simultaneously minimizing the rupture-model norm (by setting the null-space component of the rupture model to zero), and has been extended in many ways, one of which is the use of nonlinear inversion schemes such as simulated annealing algorithms that optimize some other misfit function. For example, the simulated annealing algorithm of Piatanesi and others (2007) finds the rupture model that minimizes a “cost” function which combines a least-squares and a waveform-correlation measure of misfit.All such inversions that look for a unique “best” model have at least three problems. (1) They have removed the null-space component of the rupture model—that is, an infinite family of rupture models that all fit the data equally well have been narrowed down to a single model. Some property of interest in the rupture model might have been discarded in this winnowing process. (2) Smoothing constraints are commonly used to yield a unique “best” model, in which case spatially rough rupture models will have been discarded, even if they provide a good fit to the data. (3) No estimate of confidence in the resulting rupture models can be given because the effects of unknown errors in the Green’s functions (“theory errors”) have not been assessed. In inversion for rupture behavior, these theory errors are generally larger than the data errors caused by ground noise and instrumental limitations, and so overfitting of the data is probably ubiquitous for such inversions.Recently, attention

Point sources and multipoles in inverse scattering theory

CERN Document Server

Potthast, Roland

2001-01-01

Over the last twenty years, the growing availability of computing power has had an enormous impact on the classical fields of direct and inverse scattering. The study of inverse scattering, in particular, has developed rapidly with the ability to perform computational simulations of scattering processes and led to remarkable advances in a range of applications, from medical imaging and radar to remote sensing and seismic exploration. Point Sources and Multipoles in Inverse Scattering Theory provides a survey of recent developments in inverse acoustic and electromagnetic scattering theory. Focusing on methods developed over the last six years by Colton, Kirsch, and the author, this treatment uses point sources combined with several far-reaching techniques to obtain qualitative reconstruction methods. The author addresses questions of uniqueness, stability, and reconstructions for both two-and three-dimensional problems.With interest in extracting information about an object through scattered waves at an all-ti...

A hybrid simulation approach for integrating safety behavior into construction planning: An earthmoving case study.

Science.gov (United States)

Goh, Yang Miang; Askar Ali, Mohamed Jawad

2016-08-01

One of the key challenges in improving construction safety and health is the management of safety behavior. From a system point of view, workers work unsafely due to system level issues such as poor safety culture, excessive production pressure, inadequate allocation of resources and time and lack of training. These systemic issues should be eradicated or minimized during planning. However, there is a lack of detailed planning tools to help managers assess the impact of their upstream decisions on worker safety behavior. Even though simulation had been used in construction planning, the review conducted in this study showed that construction safety management research had not been exploiting the potential of simulation techniques. Thus, a hybrid simulation framework is proposed to facilitate integration of safety management considerations into construction activity simulation. The hybrid framework consists of discrete event simulation (DES) as the core, but heterogeneous, interactive and intelligent (able to make decisions) agents replace traditional entities and resources. In addition, some of the cognitive processes and physiological aspects of agents are captured using system dynamics (SD) approach. The combination of DES, agent-based simulation (ABS) and SD allows a more "natural" representation of the complex dynamics in construction activities. The proposed hybrid framework was demonstrated using a hypothetical case study. In addition, due to the lack of application of factorial experiment approach in safety management simulation, the case study demonstrated sensitivity analysis and factorial experiment to guide future research. Copyright © 2015 Elsevier Ltd. All rights reserved.

Data and modelling requirements for CO2 inversions using high-frequency data

International Nuclear Information System (INIS)

Law, R.M.; Rayner, P.J.; Steele, L.P.; Enting, I.G.

2003-01-01

We explore the future possibilities for CO 2 source estimation from atmospheric concentration data by performing synthetic data experiments. Synthetic data are used to test seasonal CO 2 inversions using high-frequency data. Monthly CO 2 sources over the Australian region are calculated for inversions with data at 4-hourly frequency and averaged over 1 d, 2.5 d, 5 d, 12.17 d and 1 month. The inversion quality, as determined by bias and uncertainty, is degraded when averaging over longer periods. This shows the value of the strong but relatively short-lived signals present in high-frequency records that are removed in averaged and particularly filtered records. Sensitivity tests are performed in which the synthetic data are 'corrupted' to simulate systematic measurement errors such as intercalibration differences or to simulate transport modelling errors. The inversion is also used to estimate the effect of calibration offsets between sites. We find that at short data-averaging periods the inversion is reasonably robust to measurement-type errors. For transport-type errors, the best results are achieved for synoptic (2-5 d) timescales. Overall the tests indicate that improved source estimates should be possible by incorporating continuous measurements into CO 2 inversions

An Inverse Free-Electron-Laser accelerator

International Nuclear Information System (INIS)

Fisher, A.S.; Gallardo, J.C.; van Steenbergen, A.; Ulc, S.; Woodle, M.; Sandweiss, J.; Fang, Jyan-Min

1993-01-01

Recent work at BNL on electron acceleration using the Inverse Free-Electron Laser (IFEL) has considered a low-energy, high-gradient, multi-stage linear accelerator. Experiments are planned at BNL's Accelerator Test Facility using its 50-MeV linac and 100-GW CO 2 laser. We have built and tested a fast-excitation wiggler magnet with constant field, tapered period, and overall length of 47 cm. Vanadium-Permendur ferromagnetic laminations are stacked in alternation with copper, eddy-current-induced, field reflectors to achieve a 1.4-T peak field with a 4-mm gap and a typical period of 3 cm. The laser beam will pass through the wiggler in a low-loss, dielectric-coated stainless-steel, rectangular waveguide. The attenuation and transverse mode has been measured in waveguide sections of various lengths, with and without the dielectric. Results of 1-D and 3-D IFEL simulations, including wiggler errors, will be presented for several cases: the initial, single-module experiment with ΔE = 39 MeV, a four-module design giving ΔE = 100 MeV in a total length of 2 m, and an eight-module IFEL with ΔE = 210 MeV

Dose/volume–response relations for rectal morbidity using planned and simulated motion-inclusive dose distributions

International Nuclear Information System (INIS)

Thor, Maria; Apte, Aditya; Deasy, Joseph O.; Karlsdóttir, Àsa; Moiseenko, Vitali; Liu, Mitchell; Muren, Ludvig Paul

2013-01-01

Background and purpose: Many dose-limiting normal tissues in radiotherapy (RT) display considerable internal motion between fractions over a course of treatment, potentially reducing the appropriateness of using planned dose distributions to predict morbidity. Accounting explicitly for rectal motion could improve the predictive power of modelling rectal morbidity. To test this, we simulated the effect of motion in two cohorts. Materials and methods: The included patients (232 and 159 cases) received RT for prostate cancer to 70 and 74 Gy. Motion-inclusive dose distributions were introduced as simulations of random or systematic motion to the planned dose distributions. Six rectal morbidity endpoints were analysed. A probit model using the QUANTEC recommended parameters was also applied to the cohorts. Results: The differences in associations using the planned over the motion-inclusive dose distributions were modest. Statistically significant associations were obtained with four of the endpoints, mainly at high doses (55–70 Gy), using both the planned and the motion-inclusive dose distributions, primarily when simulating random motion. The strongest associations were observed for GI toxicity and rectal bleeding (Rs = 0.12–0.21; Rs = 0.11–0.20). Applying the probit model, significant associations were found for tenesmus and rectal bleeding (Rs = 0.13, p = 0.02). Conclusion: Equally strong associations with rectal morbidity were observed at high doses (>55 Gy), for the planned and the simulated dose distributions including in particular random rectal motion. Future studies should explore patient-specific descriptions of rectal motion to achieve improved predictive power

SeisFlows-Flexible waveform inversion software

Science.gov (United States)

Modrak, Ryan T.; Borisov, Dmitry; Lefebvre, Matthieu; Tromp, Jeroen

2018-06-01

SeisFlows is an open source Python package that provides a customizable waveform inversion workflow and framework for research in oil and gas exploration, earthquake tomography, medical imaging, and other areas. New methods can be rapidly prototyped in SeisFlows by inheriting from default inversion or migration classes, and code can be tested on 2D examples before application to more expensive 3D problems. Wave simulations must be performed using an external software package such as SPECFEM3D. The ability to interface with external solvers lends flexibility, and the choice of SPECFEM3D as a default option provides optional GPU acceleration and other useful capabilities. Through support for massively parallel solvers and interfaces for high-performance computing (HPC) systems, inversions with thousands of seismic traces and billions of model parameters can be performed. So far, SeisFlows has run on clusters managed by the Department of Defense, Chevron Corp., Total S.A., Princeton University, and the University of Alaska, Fairbanks.

Effect of inversion layer at iron pyrite surface on photovoltaic device

Science.gov (United States)

Uchiyama, Shunsuke; Ishikawa, Yasuaki; Uraoka, Yukiharu

2018-03-01

Iron pyrite has great potential as a thin-film solar cell material because it has high optical absorption, low cost, and is earth-abundant. However, previously reported iron pyrite solar cells showed poor photovoltaic characteristics. Here, we have numerically simulated its photovoltaic characteristics and band structures by utilizing a two-dimensional (2D) device simulator, ATLAS, to evaluate the effects of an inversion layer at the surface and a high density of deep donor defect states in the bulk. We found that previous device structures did not consider the inversion layer at the surface region of iron pyrite, which made it difficult to obtain the conversion efficiency. Therefore, we remodeled the device structure and suggested that removing the inversion layer and reducing the density of deep donor defect states would lead to a high conversion efficiency of iron pyrite solar cells.

Statistical Inversion of Absolute Permeability in Single-phase Darcy Flow

KAUST Repository

Strauss, Thilo; Fan, Xiaolin; Sun, Shuyu; Khan, Taufiquar

2015-01-01

In this paper, we formulate the permeability inverse problem in the Bayesian framework using total variation (TV) and fp (0 < p δ 2) regularization prior. We use the Markov Chain Monte Carlo (MCMC) method for sampling the posterior distribution to solve the ill-posed inverse problem. We present simulations to estimate the distribution for each pixel for the image reconstruction of the absolute permeability.

Statistical Inversion of Absolute Permeability in Single-phase Darcy Flow

KAUST Repository

Strauss, Thilo

2015-06-01

In this paper, we formulate the permeability inverse problem in the Bayesian framework using total variation (TV) and fp (0 < p δ 2) regularization prior. We use the Markov Chain Monte Carlo (MCMC) method for sampling the posterior distribution to solve the ill-posed inverse problem. We present simulations to estimate the distribution for each pixel for the image reconstruction of the absolute permeability.

Simulation-based power calculations for planning a two-stage individual participant data meta-analysis.

Science.gov (United States)

Ensor, Joie; Burke, Danielle L; Snell, Kym I E; Hemming, Karla; Riley, Richard D

2018-05-18

Researchers and funders should consider the statistical power of planned Individual Participant Data (IPD) meta-analysis projects, as they are often time-consuming and costly. We propose simulation-based power calculations utilising a two-stage framework, and illustrate the approach for a planned IPD meta-analysis of randomised trials with continuous outcomes where the aim is to identify treatment-covariate interactions. The simulation approach has four steps: (i) specify an underlying (data generating) statistical model for trials in the IPD meta-analysis; (ii) use readily available information (e.g. from publications) and prior knowledge (e.g. number of studies promising IPD) to specify model parameter values (e.g. control group mean, intervention effect, treatment-covariate interaction); (iii) simulate an IPD meta-analysis dataset of a particular size from the model, and apply a two-stage IPD meta-analysis to obtain the summary estimate of interest (e.g. interaction effect) and its associated p-value; (iv) repeat the previous step (e.g. thousands of times), then estimate the power to detect a genuine effect by the proportion of summary estimates with a significant p-value. In a planned IPD meta-analysis of lifestyle interventions to reduce weight gain in pregnancy, 14 trials (1183 patients) promised their IPD to examine a treatment-BMI interaction (i.e. whether baseline BMI modifies intervention effect on weight gain). Using our simulation-based approach, a two-stage IPD meta-analysis has meta-analysis was appropriate. Pre-specified adjustment for prognostic factors would increase power further. Incorrect dichotomisation of BMI would reduce power by over 20%, similar to immediately throwing away IPD from ten trials. Simulation-based power calculations could inform the planning and funding of IPD projects, and should be used routinely.

Refractive index inversion based on Mueller matrix method

Science.gov (United States)

Fan, Huaxi; Wu, Wenyuan; Huang, Yanhua; Li, Zhaozhao

2016-03-01

Based on Stokes vector and Jones vector, the correlation between Mueller matrix elements and refractive index was studied with the result simplified, and through Mueller matrix way, the expression of refractive index inversion was deduced. The Mueller matrix elements, under different incident angle, are simulated through the expression of specular reflection so as to analyze the influence of the angle of incidence and refractive index on it, which is verified through the measure of the Mueller matrix elements of polished metal surface. Research shows that, under the condition of specular reflection, the result of Mueller matrix inversion is consistent with the experiment and can be used as an index of refraction of inversion method, and it provides a new way for target detection and recognition technology.

Virtual environment simulation as a tool to support evacuation planning

International Nuclear Information System (INIS)

Mol, Antonio C.; Grecco, Claudio H.S.; Santos, Isaac J.A.L.; Carvalho, Paulo V.R.; Jorge, Carlos A.F.; Sales, Douglas S.; Couto, Pedro M.; Botelho, Felipe M.; Bastos, Felipe R.

2007-01-01

This work is a preliminary study of the use of a free game-engine as a tool to build and to navigate in virtual environments, with a good degree of realism, for virtual simulations of evacuation from building and risk zones. To achieve this goal, some adjustments in the game engine have been implemented. A real building with four floors, consisting of some rooms with furniture and people, has been virtually implemented. Simulations of simple different evacuation scenarios have been performed, measuring the total time spent in each case. The measured times have been compared with their corresponding real evacuation times, measured in the real building. The first results have demonstrated that the virtual environment building with the free game engine is capable to reproduce the real situation with a satisfactory level. However, it is important to emphasize that such virtual simulations serve only as an aid in the planning of real evacuation simulations, and as such must never substitute the later. (author)

Training-Image Based Geostatistical Inversion Using a Spatial Generative Adversarial Neural Network

Science.gov (United States)

Laloy, Eric; Hérault, Romain; Jacques, Diederik; Linde, Niklas

2018-01-01

Probabilistic inversion within a multiple-point statistics framework is often computationally prohibitive for high-dimensional problems. To partly address this, we introduce and evaluate a new training-image based inversion approach for complex geologic media. Our approach relies on a deep neural network of the generative adversarial network (GAN) type. After training using a training image (TI), our proposed spatial GAN (SGAN) can quickly generate 2-D and 3-D unconditional realizations. A key characteristic of our SGAN is that it defines a (very) low-dimensional parameterization, thereby allowing for efficient probabilistic inversion using state-of-the-art Markov chain Monte Carlo (MCMC) methods. In addition, available direct conditioning data can be incorporated within the inversion. Several 2-D and 3-D categorical TIs are first used to analyze the performance of our SGAN for unconditional geostatistical simulation. Training our deep network can take several hours. After training, realizations containing a few millions of pixels/voxels can be produced in a matter of seconds. This makes it especially useful for simulating many thousands of realizations (e.g., for MCMC inversion) as the relative cost of the training per realization diminishes with the considered number of realizations. Synthetic inversion case studies involving 2-D steady state flow and 3-D transient hydraulic tomography with and without direct conditioning data are used to illustrate the effectiveness of our proposed SGAN-based inversion. For the 2-D case, the inversion rapidly explores the posterior model distribution. For the 3-D case, the inversion recovers model realizations that fit the data close to the target level and visually resemble the true model well.

Learning of spatial relationships between observed and imitated actions allows invariant inverse computation in the frontal mirror neuron system.

Science.gov (United States)

Oh, Hyuk; Gentili, Rodolphe J; Reggia, James A; Contreras-Vidal, José L

2011-01-01

It has been suggested that the human mirror neuron system can facilitate learning by imitation through coupling of observation and action execution. During imitation of observed actions, the functional relationship between and within the inferior frontal cortex, the posterior parietal cortex, and the superior temporal sulcus can be modeled within the internal model framework. The proposed biologically plausible mirror neuron system model extends currently available models by explicitly modeling the intraparietal sulcus and the superior parietal lobule in implementing the function of a frame of reference transformation during imitation. Moreover, the model posits the ventral premotor cortex as performing an inverse computation. The simulations reveal that: i) the transformation system can learn and represent the changes in extrinsic to intrinsic coordinates when an imitator observes a demonstrator; ii) the inverse model of the imitator's frontal mirror neuron system can be trained to provide the motor plans for the imitated actions.

Comparison of DVH parameters and loading patterns of standard loading, manual and inverse optimization for intracavitary brachytherapy on a subset of tandem/ovoid cases

International Nuclear Information System (INIS)

Jamema, Swamidas V.; Kirisits, Christian; Mahantshetty, Umesh; Trnkova, Petra; Deshpande, Deepak D.; Shrivastava, Shyam K.; Poetter, Richard

2010-01-01

Purpose: Comparison of inverse planning with the standard clinical plan and with the manually optimized plan based on dose-volume parameters and loading patterns. Materials and methods: Twenty-eight patients who underwent MRI based HDR brachytherapy for cervix cancer were selected for this study. Three plans were calculated for each patient: (1) standard loading, (2) manual optimized, and (3) inverse optimized. Dosimetric outcomes from these plans were compared based on dose-volume parameters. The ratio of Total Reference Air Kerma of ovoid to tandem (TRAK O/T ) was used to compare the loading patterns. Results: The volume of HR CTV ranged from 9-68 cc with a mean of 41(±16.2)cc. Mean V100 for standard, manual optimized and inverse plans was found to be not significant (p = 0.35, 0.38, 0.4). Dose to bladder (7.8 ± 1.6 Gy) and sigmoid (5.6 ± 1.4 Gy) was high for standard plans; Manual optimization reduced the dose to bladder (7.1 ± 1.7 Gy p = 0.006) and sigmoid (4.5 ± 1.0 Gy p = 0.005) without compromising the HR CTV coverage. The inverse plan resulted in a significant reduction to bladder dose (6.5 ± 1.4 Gy, p = 0.002). TRAK was found to be 0.49(±0.02), 0.44(±0.04) and 0.40(±0.04)cGy m -2 for the standard loading, manual optimized and inverse plans, respectively. It was observed that TRAK O/T was 0.82(±0.05), 1.7(±1.04) and 1.41(±0.93) for standard loading, manual optimized and inverse plans, respectively, while this ratio was 1 for the traditional loading pattern. Conclusions: Inverse planning offers good sparing of critical structures without compromising the target coverage. The average loading pattern of the whole patient cohort deviates from the standard Fletcher loading pattern.

Comparison of DVH parameters and loading patterns of standard loading, manual and inverse optimization for intracavitary brachytherapy on a subset of tandem/ovoid cases.

Science.gov (United States)

Jamema, Swamidas V; Kirisits, Christian; Mahantshetty, Umesh; Trnkova, Petra; Deshpande, Deepak D; Shrivastava, Shyam K; Pötter, Richard

2010-12-01

Comparison of inverse planning with the standard clinical plan and with the manually optimized plan based on dose-volume parameters and loading patterns. Twenty-eight patients who underwent MRI based HDR brachytherapy for cervix cancer were selected for this study. Three plans were calculated for each patient: (1) standard loading, (2) manual optimized, and (3) inverse optimized. Dosimetric outcomes from these plans were compared based on dose-volume parameters. The ratio of Total Reference Air Kerma of ovoid to tandem (TRAK(O/T)) was used to compare the loading patterns. The volume of HR CTV ranged from 9-68 cc with a mean of 41(±16.2) cc. Mean V100 for standard, manual optimized and inverse plans was found to be not significant (p=0.35, 0.38, 0.4). Dose to bladder (7.8±1.6 Gy) and sigmoid (5.6±1.4 Gy) was high for standard plans; Manual optimization reduced the dose to bladder (7.1±1.7 Gy p=0.006) and sigmoid (4.5±1.0 Gy p=0.005) without compromising the HR CTV coverage. The inverse plan resulted in a significant reduction to bladder dose (6.5±1.4 Gy, p=0.002). TRAK was found to be 0.49(±0.02), 0.44(±0.04) and 0.40(±0.04) cGy m(-2) for the standard loading, manual optimized and inverse plans, respectively. It was observed that TRAK(O/T) was 0.82(±0.05), 1.7(±1.04) and 1.41(±0.93) for standard loading, manual optimized and inverse plans, respectively, while this ratio was 1 for the traditional loading pattern. Inverse planning offers good sparing of critical structures without compromising the target coverage. The average loading pattern of the whole patient cohort deviates from the standard Fletcher loading pattern. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

The role of the umbrella inversion mode in proton diffusion

Science.gov (United States)

Hassanali, Ali A.; Giberti, Federico; Sosso, Gabriele C.; Parrinello, Michele

2014-04-01

Here, using ab initio molecular dynamics (AIMD) simulations, we elucidate the role of the umbrella inversion mode of the hydronium in proton transfer (PT) in liquid water. The hydrophobic face of the hydronium oxygen experiences asymmetries in the solvent potential along the inversion coordinate and this has a rather drastic effect on the barrier for proton transfer. This behavior is coupled to the fluctuations of voids or cavities in the vicinity of the hydronium in the water network. The peculiar inversion mode can either trap or release the proton from different parts of the water network.

Inverse photoemission

International Nuclear Information System (INIS)

Namatame, Hirofumi; Taniguchi, Masaki

1994-01-01

Photoelectron spectroscopy is regarded as the most powerful means since it can measure almost perfectly the occupied electron state. On the other hand, inverse photoelectron spectroscopy is the technique for measuring unoccupied electron state by using the inverse process of photoelectron spectroscopy, and in principle, the similar experiment to photoelectron spectroscopy becomes feasible. The development of the experimental technology for inverse photoelectron spectroscopy has been carried out energetically by many research groups so far. At present, the heightening of resolution of inverse photoelectron spectroscopy, the development of inverse photoelectron spectroscope in which light energy is variable and so on are carried out. But the inverse photoelectron spectroscope for vacuum ultraviolet region is not on the market. In this report, the principle of inverse photoelectron spectroscopy and the present state of the spectroscope are described, and the direction of the development hereafter is groped. As the experimental equipment, electron guns, light detectors and so on are explained. As the examples of the experiment, the inverse photoelectron spectroscopy of semimagnetic semiconductors and resonance inverse photoelectron spectroscopy are reported. (K.I.)

An inverse optimal control problem in the electrical discharge ...

Indian Academy of Sciences (India)

Marin Gostimirovic

2018-05-10

May 10, 2018 ... Keywords. EDM process; discharge energy; heat source parameters; inverse problem; optimization. 1. Introduction .... ation, thermal modeling of the EDM process would become ..... simulation of die-sinking EDM. CIRP Ann.

Three-dimensional inverse modelling of damped elastic wave propagation in the Fourier domain

Science.gov (United States)

Petrov, Petr V.; Newman, Gregory A.

2014-09-01

3-D full waveform inversion (FWI) of seismic wavefields is routinely implemented with explicit time-stepping simulators. A clear advantage of explicit time stepping is the avoidance of solving large-scale implicit linear systems that arise with frequency domain formulations. However, FWI using explicit time stepping may require a very fine time step and (as a consequence) significant computational resources and run times. If the computational challenges of wavefield simulation can be effectively handled, an FWI scheme implemented within the frequency domain utilizing only a few frequencies, offers a cost effective alternative to FWI in the time domain. We have therefore implemented a 3-D FWI scheme for elastic wave propagation in the Fourier domain. To overcome the computational bottleneck in wavefield simulation, we have exploited an efficient Krylov iterative solver for the elastic wave equations approximated with second and fourth order finite differences. The solver does not exploit multilevel preconditioning for wavefield simulation, but is coupled efficiently to the inversion iteration workflow to reduce computational cost. The workflow is best described as a series of sequential inversion experiments, where in the case of seismic reflection acquisition geometries, the data has been laddered such that we first image highly damped data, followed by data where damping is systemically reduced. The key to our modelling approach is its ability to take advantage of solver efficiency when the elastic wavefields are damped. As the inversion experiment progresses, damping is significantly reduced, effectively simulating non-damped wavefields in the Fourier domain. While the cost of the forward simulation increases as damping is reduced, this is counterbalanced by the cost of the outer inversion iteration, which is reduced because of a better starting model obtained from the larger damped wavefield used in the previous inversion experiment. For cross-well data, it is

Robust inverse-consistent affine CT-MR registration in MRI-assisted and MRI-alone prostate radiation therapy.

Science.gov (United States)

Rivest-Hénault, David; Dowson, Nicholas; Greer, Peter B; Fripp, Jurgen; Dowling, Jason A

2015-07-01

CT-MR registration is a critical component of many radiation oncology protocols. In prostate external beam radiation therapy, it allows the propagation of MR-derived contours to reference CT images at the planning stage, and it enables dose mapping during dosimetry studies. The use of carefully registered CT-MR atlases allows the estimation of patient specific electron density maps from MRI scans, enabling MRI-alone radiation therapy planning and treatment adaptation. In all cases, the precision and accuracy achieved by registration influences the quality of the entire process. Most current registration algorithms do not robustly generalize and lack inverse-consistency, increasing the risk of human error and acting as a source of bias in studies where information is propagated in a particular direction, e.g. CT to MR or vice versa. In MRI-based treatment planning where both CT and MR scans serve as spatial references, inverse-consistency is critical, if under-acknowledged. A robust, inverse-consistent, rigid/affine registration algorithm that is well suited to CT-MR alignment in prostate radiation therapy is presented. The presented method is based on a robust block-matching optimization process that utilises a half-way space definition to maintain inverse-consistency. Inverse-consistency substantially reduces the influence of the order of input images, simplifying analysis, and increasing robustness. An open source implementation is available online at http://aehrc.github.io/Mirorr/. Experimental results on a challenging 35 CT-MR pelvis dataset demonstrate that the proposed method is more accurate than other popular registration packages and is at least as accurate as the state of the art, while being more robust and having an order of magnitude higher inverse-consistency than competing approaches. The presented results demonstrate that the proposed registration algorithm is readily applicable to prostate radiation therapy planning. Copyright © 2015. Published by

Automated IMRT planning with regional optimization using planning scripts.

Science.gov (United States)

Xhaferllari, Ilma; Wong, Eugene; Bzdusek, Karl; Lock, Michael; Chen, Jeff

2013-01-07

Intensity-modulated radiation therapy (IMRT) has become a standard technique in radiation therapy for treating different types of cancers. Various class solutions have been developed for simple cases (e.g., localized prostate, whole breast) to generate IMRT plans efficiently. However, for more complex cases (e.g., head and neck, pelvic nodes), it can be time-consuming for a planner to generate optimized IMRT plans. To generate optimal plans in these more complex cases which generally have multiple target volumes and organs at risk, it is often required to have additional IMRT optimization structures such as dose limiting ring structures, adjust beam geometry, select inverse planning objectives and associated weights, and additional IMRT objectives to reduce cold and hot spots in the dose distribution. These parameters are generally manually adjusted with a repeated trial and error approach during the optimization process. To improve IMRT planning efficiency in these more complex cases, an iterative method that incorporates some of these adjustment processes automatically in a planning script is designed, implemented, and validated. In particular, regional optimization has been implemented in an iterative way to reduce various hot or cold spots during the optimization process that begins with defining and automatic segmentation of hot and cold spots, introducing new objectives and their relative weights into inverse planning, and turn this into an iterative process with termination criteria. The method has been applied to three clinical sites: prostate with pelvic nodes, head and neck, and anal canal cancers, and has shown to reduce IMRT planning time significantly for clinical applications with improved plan quality. The IMRT planning scripts have been used for more than 500 clinical cases.

A Novel Inversion Method of Manufacturing Flaws in the Packaging of Conformal Load-Bearing Antenna Structure

Directory of Open Access Journals (Sweden)

P. Li

2015-01-01

Full Text Available Composite material is widely used in the conformal load-bearing antenna structure (CLAS, and the manufacturing flaws in the packaging process of the CLAS will lead to the degradation of its wave-transparent property. For this problem, a novel inverse method of the flaw’s dimension by antenna-radome system’s far field data has been proposed. Two steps are included in the inversion: the first one is the inversion from the far filed data to the transmission coefficient of the CLAS’s radome; the second one is the inversion from the transmission coefficient to the flaw’s dimension. The inversion also has a good potential for the separable multilayer composite material radome. A 12.5 GHz CLAS with microstrip antenna array is used in the simulation, which indicates the effectiveness of the novel inversion method. Finally, the error analysis of the inversion method is presented by numerical simulation; the results is that the inversed error could be less than 10%, if the measurement error of far field data is less than 0.45 dB in amplitude and ±5° in phase.

Estimating surface acoustic impedance with the inverse method.

Science.gov (United States)

Piechowicz, Janusz

2011-01-01

Sound field parameters are predicted with numerical methods in sound control systems, in acoustic designs of building and in sound field simulations. Those methods define the acoustic properties of surfaces, such as sound absorption coefficients or acoustic impedance, to determine boundary conditions. Several in situ measurement techniques were developed; one of them uses 2 microphones to measure direct and reflected sound over a planar test surface. Another approach is used in the inverse boundary elements method, in which estimating acoustic impedance of a surface is expressed as an inverse boundary problem. The boundary values can be found from multipoint sound pressure measurements in the interior of a room. This method can be applied to arbitrarily-shaped surfaces. This investigation is part of a research programme on using inverse methods in industrial room acoustics.

Magnetic field sensor based on asymmetric inverse Wiedemann effect

Czech Academy of Sciences Publication Activity Database

Kraus, Luděk; Malátek, M.; Dvořák, M.

2008-01-01

Roč. 142, č. 2 (2008), s. 468-473 ISSN 0924-4247 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnetic field sensor * inverse Wiedemann effect * off-diagonal magnetoimpedance * amorphous ribbon Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.724, year: 2008

COMPENSATED INVERSE PID CONTROLLER FOR ACTIVE VIBRATION CONTROL WITH PIEZOELECTRIC PATCHES: MODELING, SIMULATION AND IMPLEMENTATION

Directory of Open Access Journals (Sweden)

Asan Gani

2010-09-01

Full Text Available Active vibration control of the first three modes of a vibrating cantilever beam using collocated piezoelectric sensor and actuator is examined in this paper. To achieve this, a model based on Euler-Bernoulli beam equation is adopted and extended to the case of three bonded piezoelectric patches that act as sensor, actuator and exciter respectively. A compensated inverse PID controller has been designed and developed to damp first three modes of vibration. Controllers have been designed for each mode and these are later combined in parallel to damp any of the three modes. Individual controller gives better reduction in sensor output for the second and third modes while the combined controller performs better for the first mode. Simulation studies are carried out using MATLAB. These results are compared and verified experimentally and the real-time implementation is carried out with xPC-target toolbox in MATLAB

Inverse load calculation procedure for offshore wind turbines and application to a 5-MW wind turbine support structure: Inverse load calculation procedure for offshore wind turbines

Energy Technology Data Exchange (ETDEWEB)

Pahn, T. [Pahn Ingenieure, Am Seegraben 17b 03051 Cottbus Germany; Rolfes, R. [Institut f?r Statik und Dynamik, Leibniz Universit?t Hannover, Appelstra?e 9A 30167 Hannover Germany; Jonkman, J. [National Renewable Energy Laboratory, 15013 Denver West Parkway Golden Colorado 80401 USA

2017-02-20

A significant number of wind turbines installed today have reached their designed service life of 20 years, and the number will rise continuously. Most of these turbines promise a more economical performance if they operate for more than 20 years. To assess a continued operation, we have to analyze the load-bearing capacity of the support structure with respect to site-specific conditions. Such an analysis requires the comparison of the loads used for the design of the support structure with the actual loads experienced. This publication presents the application of a so-called inverse load calculation to a 5-MW wind turbine support structure. The inverse load calculation determines external loads derived from a mechanical description of the support structure and from measured structural responses. Using numerical simulations with the software fast, we investigated the influence of wind-turbine-specific effects such as the wind turbine control or the dynamic interaction between the loads and the support structure to the presented inverse load calculation procedure. fast is used to study the inverse calculation of simultaneously acting wind and wave loads, which has not been carried out until now. Furthermore, the application of the inverse load calculation procedure to a real 5-MW wind turbine support structure is demonstrated. In terms of this practical application, setting up the mechanical system for the support structure using measurement data is discussed. The paper presents results for defined load cases and assesses the accuracy of the inversely derived dynamic loads for both the simulations and the practical application.

Inverse Design of a SOI T-junction Polarization Beamsplitter

Science.gov (United States)

Ye, Zi; Qiu, Jifang; Meng, Chong; Zheng, Li; Dong, Zhenli; Wu, Jian

2017-06-01

A SOI T-junction polarization beamsplitter with an ultra-compact footprint of 2.8×2.8μm2 is designed based on the method of inverse design. Simulated results show that the conversion efficiencies for TE and TM lights are 73.34% (simulated insertion loss of 2dB) and 80.4% (simulated insertion loss of 1.7dB) at 1550nm, respectively; the simulated extinction ratios for TE and TM lights are 19.3dB and 13.99dB at 1558nm, respectively.

Automated Planning of Tangential Breast Intensity-Modulated Radiotherapy Using Heuristic Optimization

International Nuclear Information System (INIS)

Purdie, Thomas G.; Dinniwell, Robert E.; Letourneau, Daniel; Hill, Christine; Sharpe, Michael B.

2011-01-01

Purpose: To present an automated technique for two-field tangential breast intensity-modulated radiotherapy (IMRT) treatment planning. Method and Materials: A total of 158 planned patients with Stage 0, I, and II breast cancer treated using whole-breast IMRT were retrospectively replanned using automated treatment planning tools. The tools developed are integrated into the existing clinical treatment planning system (Pinnacle 3 ) and are designed to perform the manual volume delineation, beam placement, and IMRT treatment planning steps carried out by the treatment planning radiation therapist. The automated algorithm, using only the radio-opaque markers placed at CT simulation as inputs, optimizes the tangential beam parameters to geometrically minimize the amount of lung and heart treated while covering the whole-breast volume. The IMRT parameters are optimized according to the automatically delineated whole-breast volume. Results: The mean time to generate a complete treatment plan was 6 min, 50 s ± 1 min 12 s. For the automated plans, 157 of 158 plans (99%) were deemed clinically acceptable, and 138 of 158 plans (87%) were deemed clinically improved or equal to the corresponding clinical plan when reviewed in a randomized, double-blinded study by one experienced breast radiation oncologist. In addition, overall the automated plans were dosimetrically equivalent to the clinical plans when scored for target coverage and lung and heart doses. Conclusion: We have developed robust and efficient automated tools for fully inversed planned tangential breast IMRT planning that can be readily integrated into clinical practice. The tools produce clinically acceptable plans using only the common anatomic landmarks from the CT simulation process as an input. We anticipate the tools will improve patient access to high-quality IMRT treatment by simplifying the planning process and will reduce the effort and cost of incorporating more advanced planning into clinical practice.

Photon energy-modulated radiotherapy: Monte Carlo simulation and treatment planning study

Energy Technology Data Exchange (ETDEWEB)

Park, Jong Min; Kim, Jung-in; Heon Choi, Chang; Chie, Eui Kyu; Kim, Il Han; Ye, Sung-Joon [Interdiciplinary Program in Radiation Applied Life Science, Seoul National University, Seoul, 110-744, Korea and Department of Radiation Oncology, Seoul National University Hospital, Seoul, 110-744 (Korea, Republic of); Interdiciplinary Program in Radiation Applied Life Science, Seoul National University, Seoul, 110-744 (Korea, Republic of); Department of Radiation Oncology, Seoul National University Hospital, Seoul, 110-744 (Korea, Republic of); Interdiciplinary Program in Radiation Applied Life Science, Seoul National University, Seoul, 110-744 (Korea, Republic of) and Department of Radiation Oncology, Seoul National University Hospital, Seoul, 110-744 (Korea, Republic of); Interdiciplinary Program in Radiation Applied Life Science, Seoul National University, Seoul, 110-744 (Korea, Republic of); Department of Radiation Oncology, Seoul National University Hospital, Seoul, 110-744 (Korea, Republic of) and Department of Intelligent Convergence Systems, Seoul National University, Seoul, 151-742 (Korea, Republic of)

2012-03-15

Purpose: To demonstrate the feasibility of photon energy-modulated radiotherapy during beam-on time. Methods: A cylindrical device made of aluminum was conceptually proposed as an energy modulator. The frame of the device was connected with 20 tubes through which mercury could be injected or drained to adjust the thickness of mercury along the beam axis. In Monte Carlo (MC) simulations, a flattening filter of 6 or 10 MV linac was replaced with the device. The thickness of mercury inside the device varied from 0 to 40 mm at the field sizes of 5 x 5 cm{sup 2} (FS5), 10 x 10 cm{sup 2} (FS10), and 20 x 20 cm{sup 2} (FS20). At least 5 billion histories were followed for each simulation to create phase space files at 100 cm source to surface distance (SSD). In-water beam data were acquired by additional MC simulations using the above phase space files. A treatment planning system (TPS) was commissioned to generate a virtual machine using the MC-generated beam data. Intensity modulated radiation therapy (IMRT) plans for six clinical cases were generated using conventional 6 MV, 6 MV flattening filter free, and energy-modulated photon beams of the virtual machine. Results: As increasing the thickness of mercury, Percentage depth doses (PDD) of modulated 6 and 10 MV after the depth of dose maximum were continuously increased. The amount of PDD increase at the depth of 10 and 20 cm for modulated 6 MV was 4.8% and 5.2% at FS5, 3.9% and 5.0% at FS10 and 3.2%-4.9% at FS20 as increasing the thickness of mercury from 0 to 20 mm. The same for modulated 10 MV was 4.5% and 5.0% at FS5, 3.8% and 4.7% at FS10 and 4.1% and 4.8% at FS20 as increasing the thickness of mercury from 0 to 25 mm. The outputs of modulated 6 MV with 20 mm mercury and of modulated 10 MV with 25 mm mercury were reduced into 30%, and 56% of conventional linac, respectively. The energy-modulated IMRT plans had less integral doses than 6 MV IMRT or 6 MV flattening filter free plans for tumors located in the

A Bayesian optimal design for degradation tests based on the inverse Gaussian process

Energy Technology Data Exchange (ETDEWEB)

Peng, Weiwen; Liu, Yu; Li, Yan Feng; Zhu, Shun Peng; Huang, Hong Zhong [University of Electronic Science and Technology of China, Chengdu (China)

2014-10-15

The inverse Gaussian process is recently introduced as an attractive and flexible stochastic process for degradation modeling. This process has been demonstrated as a valuable complement for models that are developed on the basis of the Wiener and gamma processes. We investigate the optimal design of the degradation tests on the basis of the inverse Gaussian process. In addition to an optimal design with pre-estimated planning values of model parameters, we also address the issue of uncertainty in the planning values by using the Bayesian method. An average pre-posterior variance of reliability is used as the optimization criterion. A trade-off between sample size and number of degradation observations is investigated in the degradation test planning. The effects of priors on the optimal designs and on the value of prior information are also investigated and quantified. The degradation test planning of a GaAs Laser device is performed to demonstrate the proposed method.

RFDR with Adiabatic Inversion Pulses: Application to Internuclear Distance Measurements

International Nuclear Information System (INIS)

Leppert, Joerg; Ohlenschlaeger, Oliver; Goerlach, Matthias; Ramachandran, Ramadurai

2004-01-01

In the context of the structural characterisation of biomolecular systems via MAS solid state NMR, the potential utility of homonuclear dipolar recoupling with adiabatic inversion pulses has been assessed via numerical simulations and experimental measurements. The results obtained suggest that it is possible to obtain reliable estimates of internuclear distances via an analysis of the initial cross-peak intensity buildup curves generated from two-dimensional adiabatic inversion pulse driven longitudinal magnetisation exchange experiments

A Simulation for Managing Complexity in Sales and Operations Planning Decisions

Science.gov (United States)

DuHadway, Scott; Dreyfus, David

2017-01-01

Within the classroom it is often difficult to convey the complexities and intricacies that go into making sales and operations planning decisions. This article describes an in-class simulation that allows students to gain hands-on experience with the complexities in making forecasting, inventory, and supplier selection decisions as part of the…

77 FR 31026 - Use of Computer Simulation of the United States Blood Supply in Support of Planning for Emergency...

Science.gov (United States)

2012-05-24

...] Use of Computer Simulation of the United States Blood Supply in Support of Planning for Emergency... entitled: ``Use of Computer Simulation of the United States Blood Supply in Support of Planning for... and panel discussions with experts from academia, regulated industry, government, and other...

Metamodel-based inverse method for parameter identification: elastic-plastic damage model

Science.gov (United States)

Huang, Changwu; El Hami, Abdelkhalak; Radi, Bouchaïb

2017-04-01

This article proposed a metamodel-based inverse method for material parameter identification and applies it to elastic-plastic damage model parameter identification. An elastic-plastic damage model is presented and implemented in numerical simulation. The metamodel-based inverse method is proposed in order to overcome the disadvantage in computational cost of the inverse method. In the metamodel-based inverse method, a Kriging metamodel is constructed based on the experimental design in order to model the relationship between material parameters and the objective function values in the inverse problem, and then the optimization procedure is executed by the use of a metamodel. The applications of the presented material model and proposed parameter identification method in the standard A 2017-T4 tensile test prove that the presented elastic-plastic damage model is adequate to describe the material's mechanical behaviour and that the proposed metamodel-based inverse method not only enhances the efficiency of parameter identification but also gives reliable results.

Calculation of the inverse data space via sparse inversion

KAUST Repository

Saragiotis, Christos

2011-01-01

The inverse data space provides a natural separation of primaries and surface-related multiples, as the surface multiples map onto the area around the origin while the primaries map elsewhere. However, the calculation of the inverse data is far from trivial as theory requires infinite time and offset recording. Furthermore regularization issues arise during inversion. We perform the inversion by minimizing the least-squares norm of the misfit function by constraining the $ell_1$ norm of the solution, being the inverse data space. In this way a sparse inversion approach is obtained. We show results on field data with an application to surface multiple removal.

Planning of development strategy for establishment of advanced simulation of nuclear system

International Nuclear Information System (INIS)

Chung, Bubdong; Ko, Wonil; Kwon Junhyun

2013-12-01

In this product, the long term development plan in each technical area has been prosed with the plan of coupled code system. The consolidated code system for safety analysis has been proposing for future needs. The computing hardware needed for te advanced simulation is also proposing. The best approach for future safety analysis simulation capabilities may be a dual-path program. i. e. the development programs for an integrated analysis tool and multi-scale/multi-physic analysis tools, where the former aims at reducing uncertainty and the latter at enhancing accuracy. Integrated analysis tool with risk informed safety margin quantification It requires a significant extension of the phenomenological and geometric capabilities of existing reactor safety analysis software, capable of detailed simulations that reduce the uncertainties. Multi-scale, multi-physics analysis tools. Simplifications of complex phenomenological models and dependencies have been made in current safety analyses to accommodate computer hardware limitations. With the advent of modern computer hardware, these limitations may be removed to permit greater accuracy in representation of physical behavior of materials in design basis and beyond design basis conditions, and hence more accurate assessment of the true safety margins based on first principle methodology. The proposals can be utilized to develop the advanced simulation project and formulation of organization and establishment of high performance computing system in KAERI

Computer-Assisted Orthognathic Surgery for Patients with Cleft Lip/Palate: From Traditional Planning to Three-Dimensional Surgical Simulation.

Directory of Open Access Journals (Sweden)

Daniel Lonic

Full Text Available Although conventional two-dimensional (2D methods for orthognathic surgery planning are still popular, the use of three-dimensional (3D simulation is steadily increasing. In facial asymmetry cases such as in cleft lip/palate patients, the additional information can dramatically improve planning accuracy and outcome. The purpose of this study is to investigate which parameters are changed most frequently in transferring a traditional 2D plan to 3D simulation, and what planning parameters can be better adjusted by this method.This prospective study enrolled 30 consecutive patients with cleft lip and/or cleft palate (mean age 18.6±2.9 years, range 15 to 32 years. All patients received two-jaw single-splint orthognathic surgery. 2D orthodontic surgery plans were transferred into a 3D setting. Severe bony collisions in the ramus area after 2D plan transfer were noted. The position of the maxillo-mandibular complex was evaluated and eventually adjusted. Position changes of roll, midline, pitch, yaw, genioplasty and their frequency within the patient group were recorded as an alternation of the initial 2D plan. Patients were divided in groups of no change from the original 2D plan and changes in one, two, three and four of the aforementioned parameters as well as subgroups of unilateral, bilateral cleft lip/palate and isolated cleft palate cases. Postoperative OQLQ scores were obtained for 20 patients who finished orthodontic treatment.83.3% of 2D plans were modified, mostly concerning yaw (63.3% and midline (36.7% adjustments. Yaw adjustments had the highest mean values in total and in all subgroups. Severe bony collisions as a result of 2D planning were seen in 46.7% of patients. Possible asymmetry was regularly foreseen and corrected in the 3D simulation.Based on our findings, 3D simulation renders important information for accurate planning in complex cleft lip/palate cases involving facial asymmetry that is regularly missed in conventional 2D

Computer-Assisted Orthognathic Surgery for Patients with Cleft Lip/Palate: From Traditional Planning to Three-Dimensional Surgical Simulation

Science.gov (United States)

Lonic, Daniel; Pai, Betty Chien-Jung; Yamaguchi, Kazuaki; Chortrakarnkij, Peerasak; Lin, Hsiu-Hsia; Lo, Lun-Jou

2016-01-01

Background Although conventional two-dimensional (2D) methods for orthognathic surgery planning are still popular, the use of three-dimensional (3D) simulation is steadily increasing. In facial asymmetry cases such as in cleft lip/palate patients, the additional information can dramatically improve planning accuracy and outcome. The purpose of this study is to investigate which parameters are changed most frequently in transferring a traditional 2D plan to 3D simulation, and what planning parameters can be better adjusted by this method. Patients and Methods This prospective study enrolled 30 consecutive patients with cleft lip and/or cleft palate (mean age 18.6±2.9 years, range 15 to 32 years). All patients received two-jaw single-splint orthognathic surgery. 2D orthodontic surgery plans were transferred into a 3D setting. Severe bony collisions in the ramus area after 2D plan transfer were noted. The position of the maxillo-mandibular complex was evaluated and eventually adjusted. Position changes of roll, midline, pitch, yaw, genioplasty and their frequency within the patient group were recorded as an alternation of the initial 2D plan. Patients were divided in groups of no change from the original 2D plan and changes in one, two, three and four of the aforementioned parameters as well as subgroups of unilateral, bilateral cleft lip/palate and isolated cleft palate cases. Postoperative OQLQ scores were obtained for 20 patients who finished orthodontic treatment. Results 83.3% of 2D plans were modified, mostly concerning yaw (63.3%) and midline (36.7%) adjustments. Yaw adjustments had the highest mean values in total and in all subgroups. Severe bony collisions as a result of 2D planning were seen in 46.7% of patients. Possible asymmetry was regularly foreseen and corrected in the 3D simulation. Conclusion Based on our findings, 3D simulation renders important information for accurate planning in complex cleft lip/palate cases involving facial asymmetry that is

Renal Tumor Cryoablation Planning. The Efficiency of Simulation on Reconstructed 3D CT Scan

Directory of Open Access Journals (Sweden)

Ciprian Valerian LUCAN

2010-12-01

Full Text Available Introduction & Objective: Nephron-sparing surgical techniques risks are related to tumor relationships with adjacent anatomic structures. Complexity of the renal anatomy drives the interest to develop tools for 3D reconstruction and surgery simulation. The aim of the article was to assess the simulation on reconstructed 3D CT scan used for planning the cryoablation. Material & Method: A prospective randomized study was performed between Jan. 2007 and July 2009 on 27 patients who underwent retroperitoneoscopic T1a renal tumors cryoablation (RC. All patients were assessed preoperatively by CT scan, also used for 3D volume rendering. In the Gr.A, the patients underwent surgery planning by simulation on 3D CT scan. In the Gr.B., patients underwent standard RC. The two groups were compared in terms of surgical time, bleeding, postoperative drainage, analgesics requirement, hospital stay, time to socio-professional reintegration. Results: Fourteen patients underwent preoperative cryoablation planning (Gr.A and 13 patients underwent standard CR (Gr.B. All parameters analyzed were shorter in the Gr.A. On multivariate logistic regression, only shortens of the surgical time (138.79±5.51 min. in Gr.A. vs. 140.92±5.54 min in Gr.B. and bleeding (164.29±60.22 mL in Gr.A. vs. 215.38±100.80 mL in Gr.B. achieved statistical significance (p<0.05. The number of cryoneedles assessed by simulation had a 92.52% accuracy when compared with those effectively used. Conclusions: Simulation of the cryoablation using reconstructed 3D CT scan improves the surgical results. The application used for simulation was able to accurately assess the number of cryoneedles required for tumor ablation, their direction and approach.

Constructing inverse probability weights for continuous exposures: a comparison of methods.

Science.gov (United States)

Naimi, Ashley I; Moodie, Erica E M; Auger, Nathalie; Kaufman, Jay S

2014-03-01

Inverse probability-weighted marginal structural models with binary exposures are common in epidemiology. Constructing inverse probability weights for a continuous exposure can be complicated by the presence of outliers, and the need to identify a parametric form for the exposure and account for nonconstant exposure variance. We explored the performance of various methods to construct inverse probability weights for continuous exposures using Monte Carlo simulation. We generated two continuous exposures and binary outcomes using data sampled from a large empirical cohort. The first exposure followed a normal distribution with homoscedastic variance. The second exposure followed a contaminated Poisson distribution, with heteroscedastic variance equal to the conditional mean. We assessed six methods to construct inverse probability weights using: a normal distribution, a normal distribution with heteroscedastic variance, a truncated normal distribution with heteroscedastic variance, a gamma distribution, a t distribution (1, 3, and 5 degrees of freedom), and a quantile binning approach (based on 10, 15, and 20 exposure categories). We estimated the marginal odds ratio for a single-unit increase in each simulated exposure in a regression model weighted by the inverse probability weights constructed using each approach, and then computed the bias and mean squared error for each method. For the homoscedastic exposure, the standard normal, gamma, and quantile binning approaches performed best. For the heteroscedastic exposure, the quantile binning, gamma, and heteroscedastic normal approaches performed best. Our results suggest that the quantile binning approach is a simple and versatile way to construct inverse probability weights for continuous exposures.

Learning of Spatial Relationships between Observed and Imitated Actions allows Invariant Inverse Computation in the Frontal Mirror Neuron System

Science.gov (United States)

Oh, Hyuk; Gentili, Rodolphe J.; Reggia, James A.; Contreras-Vidal, José L.

2014-01-01

It has been suggested that the human mirror neuron system can facilitate learning by imitation through coupling of observation and action execution. During imitation of observed actions, the functional relationship between and within the inferior frontal cortex, the posterior parietal cortex, and the superior temporal sulcus can be modeled within the internal model framework. The proposed biologically plausible mirror neuron system model extends currently available models by explicitly modeling the intraparietal sulcus and the superior parietal lobule in implementing the function of a frame of reference transformation during imitation. Moreover, the model posits the ventral premotor cortex as performing an inverse computation. The simulations reveal that: i) the transformation system can learn and represent the changes in extrinsic to intrinsic coordinates when an imitator observes a demonstrator; ii) the inverse model of the imitator’s frontal mirror neuron system can be trained to provide the motor plans for the imitated actions. PMID:22255261

Fast simulated annealing inversion of surface waves on pavement using phase-velocity spectra

Science.gov (United States)

Ryden, N.; Park, C.B.

2006-01-01

The conventional inversion of surface waves depends on modal identification of measured dispersion curves, which can be ambiguous. It is possible to avoid mode-number identification and extraction by inverting the complete phase-velocity spectrum obtained from a multichannel record. We use the fast simulated annealing (FSA) global search algorithm to minimize the difference between the measured phase-velocity spectrum and that calculated from a theoretical layer model, including the field setup geometry. Results show that this algorithm can help one avoid getting trapped in local minima while searching for the best-matching layer model. The entire procedure is demonstrated on synthetic and field data for asphalt pavement. The viscoelastic properties of the top asphalt layer are taken into account, and the inverted asphalt stiffness as a function of frequency compares well with laboratory tests on core samples. The thickness and shear-wave velocity of the deeper embedded layers are resolved within 10% deviation from those values measured separately during pavement construction. The proposed method may be equally applicable to normal soil site investigation and in the field of ultrasonic testing of materials. ?? 2006 Society of Exploration Geophysicists.

Research on Joint Parameter Inversion for an Integrated Underground Displacement 3D Measuring Sensor

Directory of Open Access Journals (Sweden)

Nanying Shentu

2015-04-01

Full Text Available Underground displacement monitoring is a key means to monitor and evaluate geological disasters and geotechnical projects. There exist few practical instruments able to monitor subsurface horizontal and vertical displacements simultaneously due to monitoring invisibility and complexity. A novel underground displacement 3D measuring sensor had been proposed in our previous studies, and great efforts have been taken in the basic theoretical research of underground displacement sensing and measuring characteristics by virtue of modeling, simulation and experiments. This paper presents an innovative underground displacement joint inversion method by mixing a specific forward modeling approach with an approximate optimization inversion procedure. It can realize a joint inversion of underground horizontal displacement and vertical displacement for the proposed 3D sensor. Comparative studies have been conducted between the measured and inversed parameters of underground horizontal and vertical displacements under a variety of experimental and inverse conditions. The results showed that when experimentally measured horizontal displacements and vertical displacements are both varied within 0 ~ 30 mm, horizontal displacement and vertical displacement inversion discrepancies are generally less than 3 mm and 1 mm, respectively, under three kinds of simulated underground displacement monitoring circumstances. This implies that our proposed underground displacement joint inversion method is robust and efficient to predict the measuring values of underground horizontal and vertical displacements for the proposed sensor.

SU-E-T-213: Comparison of Treatment Efficiency of Gamma Knife SRS Plans for Brain Metastases with Different Planning Methods

Energy Technology Data Exchange (ETDEWEB)

Feng, Y [East Carolina Univ, Greenville, NC (United States); Huang, Z [East Carolina University, Greenville, NC (United States); Lo, S [Case Western Reserve University, Cleveland, OH (United States); Mayr, N; Yuh, W [University of Washington, Seattle, WA (United States)

2015-06-15

Purpose: To improve Gamma Knife SRS treatment efficiency for brain metastases and compare the differences of treatment time and radiobiological effects between two different planning methods of automatic filling and manual placement of shots with inverse planning. Methods: T1-weighted MRI images with gadolinium contrast from five patients with a single brain metastatic-lesion were used in this retrospective study. Among them, two were from primary breast cancer, two from primary melanoma cancer and one from primary prostate cancer. For each patient, two plans were generated in Leksell GammaPlan10.1.1 for radiosurgical treatment with a Leksell GammaKnife Perfexion machine: one with automatic filling, automatic sector configuration and inverse optimization (Method1); and the other with manual placement of shots, manual setup of collimator sizes, manual setup of sector blocking and inverse optimization (Method2). Dosimetric quality of the plans was evaluated with parameters of Coverage, Selectivity, Gradient-Index and DVH. Beam-on Time, Number-of-Shots and Tumor Control Probability(TCP) were compared for the two plans while keeping their dosimetric quality very similar. Relative reduction of Beam-on Time and Number-of-Shots were calculated as the ratios among the two plans and used for quantitative analysis. Results: With very similar dosimetric and radiobiological plan quality, plans created with Method 2 had significantly reduced treatment time. Relative reduction of Beam-on Time ranged from 20% to 51 % (median:29%,p=0.001), and reduction of Number-of-Shots ranged from 5% to 67% (median:40%,p=0.0002), respectively. Time of plan creation for Method1 and Method2 was similar, approximately 20 minutes, excluding the time for tumor delineation. TCP calculated for the tumors from differential DVHs did not show significant difference between the two plans (p=0.35). Conclusion: The method of manual setup combined with inverse optimization in LGP for treatment of brain

SU-E-T-213: Comparison of Treatment Efficiency of Gamma Knife SRS Plans for Brain Metastases with Different Planning Methods

International Nuclear Information System (INIS)

Feng, Y; Huang, Z; Lo, S; Mayr, N; Yuh, W

2015-01-01

Purpose: To improve Gamma Knife SRS treatment efficiency for brain metastases and compare the differences of treatment time and radiobiological effects between two different planning methods of automatic filling and manual placement of shots with inverse planning. Methods: T1-weighted MRI images with gadolinium contrast from five patients with a single brain metastatic-lesion were used in this retrospective study. Among them, two were from primary breast cancer, two from primary melanoma cancer and one from primary prostate cancer. For each patient, two plans were generated in Leksell GammaPlan10.1.1 for radiosurgical treatment with a Leksell GammaKnife Perfexion machine: one with automatic filling, automatic sector configuration and inverse optimization (Method1); and the other with manual placement of shots, manual setup of collimator sizes, manual setup of sector blocking and inverse optimization (Method2). Dosimetric quality of the plans was evaluated with parameters of Coverage, Selectivity, Gradient-Index and DVH. Beam-on Time, Number-of-Shots and Tumor Control Probability(TCP) were compared for the two plans while keeping their dosimetric quality very similar. Relative reduction of Beam-on Time and Number-of-Shots were calculated as the ratios among the two plans and used for quantitative analysis. Results: With very similar dosimetric and radiobiological plan quality, plans created with Method 2 had significantly reduced treatment time. Relative reduction of Beam-on Time ranged from 20% to 51 % (median:29%,p=0.001), and reduction of Number-of-Shots ranged from 5% to 67% (median:40%,p=0.0002), respectively. Time of plan creation for Method1 and Method2 was similar, approximately 20 minutes, excluding the time for tumor delineation. TCP calculated for the tumors from differential DVHs did not show significant difference between the two plans (p=0.35). Conclusion: The method of manual setup combined with inverse optimization in LGP for treatment of brain

PDCI Wide-Area Damping Control: PSLF Simulations of the 2016 Open and Closed Loop Test Plan

Energy Technology Data Exchange (ETDEWEB)

Wilches Bernal, Felipe [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pierre, Brian Joseph [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Elliott, Ryan Thomas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Schoenwald, David A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Byrne, Raymond H. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Neely, Jason C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Trudnowski, Daniel J. [Montana Tech of the Univ. of Montana, Butte, MT (United States); Donnelly, Matthew K. [Montana Tech of the Univ. of Montana, Butte, MT (United States)

2017-03-01

To demonstrate and validate the performance of the wide-are a damping control system, the project plans to conduct closed-loop tests on the PDCI in summer/fall 2016. A test plan details the open and closed loop tests to be conducted on the P DCI using the wide-area damping control system. To ensure the appropriate level of preparedness, simulations were performed in order to predict and evaluate any possible unsafe operations before hardware experiments are attempted. This report contains the result s from these simulations using the power system dynamics software PSLF (Power System Load Flow, trademark of GE). The simulations use the WECC (Western Electricity Coordinating Council) 2016 light summer and heavy summer base cases.

Inverse Modeling of Emissions and their Time Profiles

Czech Academy of Sciences Publication Activity Database

Resler, Jaroslav; Eben, Kryštof; Juruš, Pavel; Liczki, Jitka

2010-01-01

Roč. 1, č. 4 (2010), s. 288-295 ISSN 1309-1042 R&D Projects: GA MŽP SP/1A4/107/07 Grant - others:COST(XE) ES0602 Institutional research plan: CEZ:AV0Z10300504 Keywords : 4DVar * inverse modeling * diurnal time profile of emission * CMAQ adjoint * satellite observations Subject RIV: DG - Athmosphere Sciences, Meteorology

Simulation of textile manufacturing processes for planning, scheduling, and quality control purposes

Science.gov (United States)

Cropper, A. E.; Wang, Z.

1995-08-01

Simulation, as a management information tool, has been applied to engineering manufacture and assembly operations. The application of the principles to textile manufacturing (fiber to fabric) is discussed. The particular problems and solutions in applying the simulation software package to the yarn production processes are discussed with an indication of how the software achieves the production schedule. The system appears to have application in planning, scheduling, and quality assurance. The latter being a result of the traceability possibilities through a process involving mixing and splitting of material.

Geant4 simulation of ion chambers response to 60Co spectrum of LNMRI/IRD Shepherd 81-14D Radiator

Science.gov (United States)

Queiroz Filho, P. P.; Da Silva, C. N. M.

2018-03-01

The National Ionizing Radiation Metrology Laboratory of the Radioprotection and Dosimetry Institute (LNMRI / IRD) has recently acquired a Shepherd 81-14D Radiator. In this work we simulate, using Geant4, the behavior with the inverse square law radiation for 3 models of PTW spherical chambers used in radioprotection, a relevant information to planning the measurements. We did the corrections for the attenuation and scattering in the air for each distance, where we used the 60Co spectrum simulated previously.

Production Planning with Respect to Uncertainties. Simulator Based Production Planning of Average Sized Combined Heat and Power Production Plants; Produktionsplanering under osaekerhet. Simulatorbaserad produktionsplanering av medelstora kraftvaermeanlaeggningar

Energy Technology Data Exchange (ETDEWEB)

Haeggstaahl, Daniel [Maelardalen Univ., Vaesteraas (Sweden); Dotzauer, Erik [AB Fortum, Stockholm (Sweden)

2004-12-01

Production planning in Combined Heat and Power (CHP) systems is considered. The focus is on development and use of mathematical models and methods. Different aspects on production planning are discussed, including weather and load predictions. Questions relevant on the different planning horizons are illuminated. The main purpose with short-term (one week) planning is to decide when to start and stop the production units, and to decide how to use the heat storage. The main conclusion from the outline of pros and cons of commercial planning software are that several are using Mixed Integer Programming (MIP). In that sense they are similar. Building a production planning model means that the planning problem is formulated as a mathematical optimization problem. The accuracy of the input data determines the practical detail level of the model. Two alternatives to the methods used in today's commercial programs are proposed: stochastic optimization and simulator-based optimization. The basic concepts of mathematical optimization are outlined. A simulator-based model for short-term planning is developed. The purpose is to minimize the production costs, depending on the heat demand in the district heating system, prices of electricity and fuels, emission taxes and fees, etc. The problem is simplified by not including any time-linking conditions. The process model is developed in IPSEpro, a heat and mass-balance software from SimTech Simulation Technology. TOMLAB, an optimization toolbox in MATLAB, is used as optimizer. Three different solvers are applied: glcFast, glcCluster and SNOPT. The link between TOMLAB and IPSEpro is accomplished using the Microsoft COM technology. MATLAB is the automation client and contains the control of IPSEpro and TOMLAB. The simulator-based model is applied to the CHP plant in Eskilstuna. Two days are chosen and analyzed. The optimized production is compared to the measured. A sensitivity analysis on how variations in outdoor

On dynamically consistent Jacobian inverse for non-holonomic robotic systems

Directory of Open Access Journals (Sweden)

Ratajczak Joanna

2017-12-01

Full Text Available This paper presents the dynamically consistent Jacobian inverse for non-holonomic robotic system, and its application to solving the motion planning problem. The system’s kinematics are represented by a driftless control system, and defined in terms of its input-output map in accordance with the endogenous configuration space approach. The dynamically consistent Jacobian inverse (DCJI has been introduced by means of a Riemannian metric in the endogenous configuration space, exploiting the reduced inertia matrix of the system’s dynamics. The consistency condition is formulated as the commutativity property of a diagram of maps. Singular configurations of DCJI are studied, and shown to coincide with the kinematic singularities. A parametric form of DCJI is derived, and used for solving example motion planning problems for the trident snake mobile robot. Some advantages in performance of DCJI in comparison to the Jacobian pseudoinverse are discovered.

Planning intensive care unit design using computer simulation modeling: optimizing integration of clinical, operational, and architectural requirements.

Science.gov (United States)

OʼHara, Susan

2014-01-01

Nurses have increasingly been regarded as critical members of the planning team as architects recognize their knowledge and value. But the nurses' role as knowledge experts can be expanded to leading efforts to integrate the clinical, operational, and architectural expertise through simulation modeling. Simulation modeling allows for the optimal merge of multifactorial data to understand the current state of the intensive care unit and predict future states. Nurses can champion the simulation modeling process and reap the benefits of a cost-effective way to test new designs, processes, staffing models, and future programming trends prior to implementation. Simulation modeling is an evidence-based planning approach, a standard, for integrating the sciences with real client data, to offer solutions for improving patient care.

NACP Regional: Original Observation Data and Biosphere and Inverse Model Outputs

Data.gov (United States)

National Aeronautics and Space Administration — This data set contains the originally-submitted observation measurement data, terrestrial biosphere model output data, and inverse model simulations that various...

NACP Regional: Original Observation Data and Biosphere and Inverse Model Outputs

Data.gov (United States)

National Aeronautics and Space Administration — ABSTRACT: This data set contains the originally-submitted observation measurement data, terrestrial biosphere model output data, and inverse model simulations that...

Comparison Between 2-D and 3-D Stiffness Matrix Model Simulation of Sasw Inversion for Pavement Structure

Directory of Open Access Journals (Sweden)

Sri Atmaja P. Rosidi

2007-01-01

Full Text Available The Spectral Analysis of Surface Wave (SASW method is a non-destructive in situ seismic technique used to assess and evaluate the material stiffness (dynamic elastic modulus and thickness of pavement layers at low strains. These values can be used analytically to calculate load capacities in order to predict the performance of pavement system. The SASW method is based on the dispersion phenomena of Rayleigh waves in layered media. In order to get the actual shear wave velocities, 2-D and 3-D models are used in the simulation of the inversion process for best fitting between theoretical and empirical dispersion curves. The objective of this study is to simulate and compare the 2-D and 3-D model of SASW analysis in the construction of the theoretical dispersion curve for pavement structure evaluation. The result showed that the dispersion curve from the 3-D model was similar with the dispersion curve of the actual pavement profile compared to the 2-D model. The wave velocity profiles also showed that the 3-D model used in the SASW analysis is able to detect all the distinct layers of flexible pavement units.

Building Performance Simulation tools for planning of energy efficiency retrofits

DEFF Research Database (Denmark)

Mondrup, Thomas Fænø; Karlshøj, Jan; Vestergaard, Flemming

2014-01-01

Designing energy efficiency retrofits for existing buildings will bring environmental, economic, social, and health benefits. However, selecting specific retrofit strategies is complex and requires careful planning. In this study, we describe a methodology for adopting Building Performance...... to energy efficiency retrofits in social housing. To generate energy savings, we focus on optimizing the building envelope. We evaluate alternative building envelope actions using procedural solar radiation and daylight simulations. In addition, we identify the digital information flow and the information...... Simulation (BPS) tools as energy and environmentally conscious decision-making aids. The methodology has been developed to screen buildings for potential improvements and to support the development of retrofit strategies. We present a case study of a Danish renovation project, implementing BPS approaches...

Use of the Inverse Approach for the Manufacture and Decoration of Food Cans

International Nuclear Information System (INIS)

Duffett, G.A.; Forgas, A.; Neamtu, L.; Naceur, H.; Batoz, J.L.; Guo, Y.Q.

2005-01-01

Innovation is a key objective in the metal packaging industry in order to produce new concepts, designs, shapes and printing. Simulation technology now allows both the can design as well as the manufacturing process to be carefully analysed before any physical prototypes or dies have been manufactured. These simulations are traditionally carried out using incremental simulation methodologies. However, much information may also be attained by using the inverse approach: the initial blank format for the can body as well as its lid may be optimised much faster, the actual decoration of the can may be evaluated and even calculated when deformation printing techniques are utilised. This paper presents some of the technical details relating to the inverse approach employed in Stampack to carry out simulations important for the manufacture of food cans that are shown via industrial

Value of epicardial potential maps in localizing pre-excitation sites for radiofrequency ablation. A simulation study

Science.gov (United States)

Hren, Rok

1998-06-01

Using computer simulations, we systematically investigated the limitations of an inverse solution that employs the potential distribution on the epicardial surface as an equivalent source model in localizing pre-excitation sites in Wolff-Parkinson-White syndrome. A model of the human ventricular myocardium that features an anatomically accurate geometry, an intramural rotating anisotropy and a computational implementation of the excitation process based on electrotonic interactions among cells, was used to simulate body surface potential maps (BSPMs) for 35 pre-excitation sites positioned along the atrioventricular ring. Two individualized torso models were used to account for variations in torso boundaries. Epicardial potential maps (EPMs) were computed using the L-curve inverse solution. The measure for accuracy of the localization was the distance between a position of the minimum in the inverse EPMs and the actual site of pre-excitation in the ventricular model. When the volume conductor properties and lead positions of the torso were precisely known and the measurement noise was added to the simulated BSPMs, the minimum in the inverse EPMs was at 12 ms after the onset on average within cm of the pre-excitation site. When the standard torso model was used to localize the sites of onset of the pre-excitation sequence initiated in individualized male and female torso models, the mean distance between the minimum and the pre-excitation site was cm for the male torso and cm for the female torso. The findings of our study indicate that a location of the minimum in EPMs computed using the inverse solution can offer non-invasive means for pre-interventional planning of the ablative treatment.

Efficient Underwater RSS Value to Distance Inversion Using the Lambert Function

Directory of Open Access Journals (Sweden)

Majid Hosseini

2014-01-01

Full Text Available There are many applications for using wireless sensor networks (WSN in ocean science; however, identifying the exact location of a sensor by itself (localization is still a challenging problem, where global positioning system (GPS devices are not applicable underwater. Precise distance measurement between two sensors is a tool of localization and received signal strength (RSS, reflecting transmission loss (TL phenomena, is widely used in terrestrial WSNs for that matter. Underwater acoustic sensor networks have not been used (UASN, due to the complexity of the TL function. In this paper, we addressed these problems by expressing underwater TL via the Lambert W function, for accurate distance inversion by the Halley method, and compared this to Newton-Raphson inversion. Mathematical proof, MATLAB simulation, and real device implementation demonstrate the accuracy and efficiency of the proposed equation in distance calculation, with fewer iterations, computation stability for short and long distances, and remarkably short processing time. Then, the sensitivities of Lambert W function and Newton-Raphson inversion to alteration in TL were examined. The simulation results showed that Lambert W function is more stable to errors than Newton-Raphson inversion. Finally, with a likelihood method, it was shown that RSS is a practical tool for distance measurement in UASN.

Inverse estimation for the unknown frost geometry on the external wall of a forced-convection pipe

International Nuclear Information System (INIS)

Chen, W.-L.; Yang, Y.-C.

2009-01-01

In this study, a conjugate gradient method based inverse algorithm is applied to estimate the unknown frost-layer boundary profile on the external wall of a pipe system using temperature measurements. It is assumed that no prior information is available on the functional form of the unknown profile; hence the procedure is classified as the function estimation in inverse calculation. The temperature data obtained from the direct problem are used to simulate the temperature measurements. The accuracy of the inverse analysis is examined by using simulated exact and inexact temperature measurements. Results show that an excellent estimation on boundary profile can be obtained for the test case considered in this study.

PULSim: User-Based Adaptable Simulation Tool for Railway Planning and Operations

Directory of Open Access Journals (Sweden)

Yong Cui

2018-01-01

Full Text Available Simulation methods are widely used in the field of railway planning and operations. Currently, several commercial software tools are available that not only provide functionality for railway simulation but also enable further evaluation and optimisation of the network for scheduling, dispatching, and capacity research. However, the various tools are all lacking with respect to the standards they utilise as well as their published interfaces. For an end-user, the basic mechanism and the assumptions built into a simulation tool are unknown, which means that the true potential of these software tools is limited. One of the most critical issues is the lack of the ability of users to define a sophisticated workflow, integrated in several rounds of simulation with adjustable parameters and settings. This paper develops and describes a user-based, customisable platform. As the preconditions of the platform, the design aspects for modelling the components of a railway system and building the workflow of railway simulation are elaborated in detail. Based on the model and the workflow, an integrated simulation platform with open interfaces is developed. Users and researchers gain the ability to rapidly develop their own algorithms, supported by the tailored simulation process in a flexible manner. The productivity of using simulation tools for further evaluation and optimisation will be significantly improved through the user-adaptable open interfaces.

FCFPYRO simulation of the first year FCF hot operation plan

International Nuclear Information System (INIS)

Liaw, J.R.; Li, S.X.; Benedict, R.W.

1996-01-01

A simulation study has been successfully completed according to the first year FCF operational plan for the treatment of EBR-II spent fuels. Material flow by nuclides for each processing step and radioactive decays during the process are considered. The FCFPYRO code package is a very useful tool to provide step-by-step information essential to the analysis of operational strategy, process chemistry, heat removal, criticality safety, and radiological health issues in FCF

Comparison of inverse Laplace and numerical inversion methods for obtaining z-depth profiles of diffraction data

International Nuclear Information System (INIS)

Xiaojing Zhu; Predecki, P.; Ballard, B.

1995-01-01

Two different inversion methods, the inverse Laplace method and the linear constrained numerical method, for retrieving the z-profiles of diffraction data from experimentally obtained i-profiles were compared using tests with a known function as the original z-profile. Two different real data situations were simulated to determine the effects of specimen thickness and missing τ-profile data at small τ-values on the retrieved z-profiles. The results indicate that although both methods are able to retrieve the z-profiles in the bulk specimens satisfactorily, the numerical method can be used for thin film samples as well. Missing τ-profile data at small τ values causes error in the retrieved z-profiles with both methods, particularly when the trend of the τ-profile at small τ is significantly changed because of the missing data. 6 refs., 3 figs

Three-Dimensional Liver Surgery Simulation: Computer-Assisted Surgical Planning with Three-Dimensional Simulation Software and Three-Dimensional Printing.

Science.gov (United States)

Oshiro, Yukio; Ohkohchi, Nobuhiro

2017-06-01

To perform accurate hepatectomy without injury, it is necessary to understand the anatomical relationship among the branches of Glisson's sheath, hepatic veins, and tumor. In Japan, three-dimensional (3D) preoperative simulation for liver surgery is becoming increasingly common, and liver 3D modeling and 3D hepatectomy simulation by 3D analysis software for liver surgery have been covered by universal healthcare insurance since 2012. Herein, we review the history of virtual hepatectomy using computer-assisted surgery (CAS) and our research to date, and we discuss the future prospects of CAS. We have used the SYNAPSE VINCENT medical imaging system (Fujifilm Medical, Tokyo, Japan) for 3D visualization and virtual resection of the liver since 2010. We developed a novel fusion imaging technique combining 3D computed tomography (CT) with magnetic resonance imaging (MRI). The fusion image enables us to easily visualize anatomic relationships among the hepatic arteries, portal veins, bile duct, and tumor in the hepatic hilum. In 2013, we developed an original software, called Liversim, which enables real-time deformation of the liver using physical simulation, and a randomized control trial has recently been conducted to evaluate the use of Liversim and SYNAPSE VINCENT for preoperative simulation and planning. Furthermore, we developed a novel hollow 3D-printed liver model whose surface is covered with frames. This model is useful for safe liver resection, has better visibility, and the production cost is reduced to one-third of a previous model. Preoperative simulation and navigation with CAS in liver resection are expected to help planning and conducting a surgery and surgical education. Thus, a novel CAS system will contribute to not only the performance of reliable hepatectomy but also to surgical education.

Chemical Source Inversion using Assimilated Constituent Observations in an Idealized Two-dimensional System

Science.gov (United States)

Tangborn, Andrew; Cooper, Robert; Pawson, Steven; Sun, Zhibin

2009-01-01

We present a source inversion technique for chemical constituents that uses assimilated constituent observations rather than directly using the observations. The method is tested with a simple model problem, which is a two-dimensional Fourier-Galerkin transport model combined with a Kalman filter for data assimilation. Inversion is carried out using a Green's function method and observations are simulated from a true state with added Gaussian noise. The forecast state uses the same spectral spectral model, but differs by an unbiased Gaussian model error, and emissions models with constant errors. The numerical experiments employ both simulated in situ and satellite observation networks. Source inversion was carried out by either direct use of synthetically generated observations with added noise, or by first assimilating the observations and using the analyses to extract observations. We have conducted 20 identical twin experiments for each set of source and observation configurations, and find that in the limiting cases of a very few localized observations, or an extremely large observation network there is little advantage to carrying out assimilation first. However, in intermediate observation densities, there decreases in source inversion error standard deviation using the Kalman filter algorithm followed by Green's function inversion by 50% to 95%.

Simulation in Pre-departure Training for Residents Planning Clinical Work in a Low-Income Country

Directory of Open Access Journals (Sweden)

Kevin R. Schwartz

2015-12-01

Full Text Available Introduction: Increasingly, pediatric and emergency medicine (EM residents are pursuing clinical rotations in low-income countries. Optimal pre-departure preparation for such rotations has not yet been established. High-fidelity simulation represents a potentially effective modality for such preparation. This study was designed to assess whether a pre-departure high-fidelity medical simulation curriculum is effective in helping to prepare residents for clinical rotations in a low-income country. Methods: 43 pediatric and EM residents planning clinical rotations in Liberia, West Africa, participated in a simulation-based curriculum focused on severe pediatric malaria and malnutrition and were then assessed by survey at three time points: pre-simulation, post-simulation, and after returning from work abroad. Results: Prior to simulation, 1/43 (2% participants reported they were comfortable with the diagnosis and management of severe malnutrition; this increased to 30/42 (71% after simulation and 24/31 (77% after working abroad. Prior to simulation, 1/43 (2% of residents reported comfort with the diagnosis and management of severe malaria; this increased to 26/42 (62% after simulation and 28/31 (90% after working abroad; 36/42 (86% of residents agreed that a simulation-based global health curriculum is more useful than a didactic curriculum alone, and 41/42 (98% felt a simulator-based curriculum should be offered to all residents planning a clinical trip to a low-income country. Conclusion: High-fidelity simulation is effective in increasing residents’ self-rated comfort in management of pediatric malaria and malnutrition and a majority of participating residents feel it should be included as a component of pre-departure training for all residents rotating clinically to low-income countries.

Solving complex maintenance planning optimization problems using stochastic simulation and multi-criteria fuzzy decision making

International Nuclear Information System (INIS)

Tahvili, Sahar; Österberg, Jonas; Silvestrov, Sergei; Biteus, Jonas

2014-01-01

One of the most important factors in the operations of many cooperations today is to maximize profit and one important tool to that effect is the optimization of maintenance activities. Maintenance activities is at the largest level divided into two major areas, corrective maintenance (CM) and preventive maintenance (PM). When optimizing maintenance activities, by a maintenance plan or policy, we seek to find the best activities to perform at each point in time, be it PM or CM. We explore the use of stochastic simulation, genetic algorithms and other tools for solving complex maintenance planning optimization problems in terms of a suggested framework model based on discrete event simulation

Solving complex maintenance planning optimization problems using stochastic simulation and multi-criteria fuzzy decision making

Energy Technology Data Exchange (ETDEWEB)

Tahvili, Sahar [Mälardalen University (Sweden); Österberg, Jonas; Silvestrov, Sergei [Division of Applied Mathematics, Mälardalen University (Sweden); Biteus, Jonas [Scania CV (Sweden)

2014-12-10

One of the most important factors in the operations of many cooperations today is to maximize profit and one important tool to that effect is the optimization of maintenance activities. Maintenance activities is at the largest level divided into two major areas, corrective maintenance (CM) and preventive maintenance (PM). When optimizing maintenance activities, by a maintenance plan or policy, we seek to find the best activities to perform at each point in time, be it PM or CM. We explore the use of stochastic simulation, genetic algorithms and other tools for solving complex maintenance planning optimization problems in terms of a suggested framework model based on discrete event simulation.

Planning Irreversible Electroporation in the Porcine Kidney: Are Numerical Simulations Reliable for Predicting Empiric Ablation Outcomes?

International Nuclear Information System (INIS)

Wimmer, Thomas; Srimathveeravalli, Govindarajan; Gutta, Narendra; Ezell, Paula C.; Monette, Sebastien; Maybody, Majid; Erinjery, Joseph P.; Durack, Jeremy C.; Coleman, Jonathan A.; Solomon, Stephen B.

2015-01-01

PurposeNumerical simulations are used for treatment planning in clinical applications of irreversible electroporation (IRE) to determine ablation size and shape. To assess the reliability of simulations for treatment planning, we compared simulation results with empiric outcomes of renal IRE using computed tomography (CT) and histology in an animal model.MethodsThe ablation size and shape for six different IRE parameter sets (70–90 pulses, 2,000–2,700 V, 70–100 µs) for monopolar and bipolar electrodes was simulated using a numerical model. Employing these treatment parameters, 35 CT-guided IRE ablations were created in both kidneys of six pigs and followed up with CT immediately and after 24 h. Histopathology was analyzed from postablation day 1.ResultsAblation zones on CT measured 81 ± 18 % (day 0, p ≤ 0.05) and 115 ± 18 % (day 1, p ≤ 0.09) of the simulated size for monopolar electrodes, and 190 ± 33 % (day 0, p ≤ 0.001) and 234 ± 12 % (day 1, p ≤ 0.0001) for bipolar electrodes. Histopathology indicated smaller ablation zones than simulated (71 ± 41 %, p ≤ 0.047) and measured on CT (47 ± 16 %, p ≤ 0.005) with complete ablation of kidney parenchyma within the central zone and incomplete ablation in the periphery.ConclusionBoth numerical simulations for planning renal IRE and CT measurements may overestimate the size of ablation compared to histology, and ablation effects may be incomplete in the periphery

Fusion Simulation Program Execution Plan

International Nuclear Information System (INIS)

Brooks, Jeffrey

2011-01-01

The overall science goal of the FSP is to develop predictive simulation capability for magnetically confined fusion plasmas at an unprecedented level of integration and fidelity. This will directly support and enable effective U.S. participation in research related to the International Thermonuclear Experimental Reactor (ITER) and the overall mission of delivering practical fusion energy. The FSP will address a rich set of scientific issues together with experimental programs, producing validated integrated physics results. This is very well aligned with the mission of the ITER Organization to coordinate with its members the integrated modeling and control of fusion plasmas, including benchmarking and validation activities. [1]. Initial FSP research will focus on two critical areas: 1) the plasma edge and 2) whole device modeling including disruption avoidance. The first of these problems involves the narrow plasma boundary layer and its complex interactions with the plasma core and the surrounding material wall. The second requires development of a computationally tractable, but comprehensive model that describes all equilibrium and dynamic processes at a sufficient level of detail to provide useful prediction of the temporal evolution of fusion plasma experiments. The initial driver for the whole device model (WDM) will be prediction and avoidance of discharge-terminating disruptions, especially at high performance, which are a critical impediment to successful operation of machines like ITER. If disruptions prove unable to be avoided, their associated dynamics and effects will be addressed in the next phase of the FSP. The FSP plan targets the needed modeling capabilities by developing Integrated Science Applications (ISAs) specific to their needs. The Pedestal-Boundary model will include boundary magnetic topology, cross-field transport of multi-species plasmas, parallel plasma transport, neutral transport, atomic physics and interactions with the plasma wall

Automated treatment planning for a dedicated multi-source intracranial radiosurgery treatment unit using projected gradient and grassfire algorithms

Energy Technology Data Exchange (ETDEWEB)

Ghobadi, Kimia; Ghaffari, Hamid R.; Aleman, Dionne M.; Jaffray, David A.; Ruschin, Mark [Department of Mechanical and Industrial Engineering, University of Toronto, 5 King' s College Road, Toronto, Ontario M5S 3G8 (Canada); Department of Radiation Oncology, University of Toronto, Radiation Medicine Program, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada)

2012-06-15

Purpose: The purpose of this work is to develop a framework to the inverse problem for radiosurgery treatment planning on the Gamma Knife{sup Registered-Sign} Perfexion Trade-Mark-Sign (PFX) for intracranial targets. Methods: The approach taken in the present study consists of two parts. First, a hybrid grassfire and sphere-packing algorithm is used to obtain shot positions (isocenters) based on the geometry of the target to be treated. For the selected isocenters, a sector duration optimization (SDO) model is used to optimize the duration of radiation delivery from each collimator size from each individual source bank. The SDO model is solved using a projected gradient algorithm. This approach has been retrospectively tested on seven manually planned clinical cases (comprising 11 lesions) including acoustic neuromas and brain metastases. Results: In terms of conformity and organ-at-risk (OAR) sparing, the quality of plans achieved with the inverse planning approach were, on average, improved compared to the manually generated plans. The mean difference in conformity index between inverse and forward plans was -0.12 (range: -0.27 to +0.03) and +0.08 (range: 0.00-0.17) for classic and Paddick definitions, respectively, favoring the inverse plans. The mean difference in volume receiving the prescribed dose (V{sub 100}) between forward and inverse plans was 0.2% (range: -2.4% to +2.0%). After plan renormalization for equivalent coverage (i.e., V{sub 100}), the mean difference in dose to 1 mm{sup 3} of brainstem between forward and inverse plans was -0.24 Gy (range: -2.40 to +2.02 Gy) favoring the inverse plans. Beam-on time varied with the number of isocenters but for the most optimal plans was on average 33 min longer than manual plans (range: -17 to +91 min) when normalized to a calibration dose rate of 3.5 Gy/min. In terms of algorithm performance, the isocenter selection for all the presented plans was performed in less than 3 s, while the SDO was performed in an

Automated treatment planning for a dedicated multi-source intracranial radiosurgery treatment unit using projected gradient and grassfire algorithms.

Science.gov (United States)

Ghobadi, Kimia; Ghaffari, Hamid R; Aleman, Dionne M; Jaffray, David A; Ruschin, Mark

2012-06-01

The purpose of this work is to develop a framework to the inverse problem for radiosurgery treatment planning on the Gamma Knife(®) Perfexion™ (PFX) for intracranial targets. The approach taken in the present study consists of two parts. First, a hybrid grassfire and sphere-packing algorithm is used to obtain shot positions (isocenters) based on the geometry of the target to be treated. For the selected isocenters, a sector duration optimization (SDO) model is used to optimize the duration of radiation delivery from each collimator size from each individual source bank. The SDO model is solved using a projected gradient algorithm. This approach has been retrospectively tested on seven manually planned clinical cases (comprising 11 lesions) including acoustic neuromas and brain metastases. In terms of conformity and organ-at-risk (OAR) sparing, the quality of plans achieved with the inverse planning approach were, on average, improved compared to the manually generated plans. The mean difference in conformity index between inverse and forward plans was -0.12 (range: -0.27 to +0.03) and +0.08 (range: 0.00-0.17) for classic and Paddick definitions, respectively, favoring the inverse plans. The mean difference in volume receiving the prescribed dose (V(100)) between forward and inverse plans was 0.2% (range: -2.4% to +2.0%). After plan renormalization for equivalent coverage (i.e., V(100)), the mean difference in dose to 1 mm(3) of brainstem between forward and inverse plans was -0.24 Gy (range: -2.40 to +2.02 Gy) favoring the inverse plans. Beam-on time varied with the number of isocenters but for the most optimal plans was on average 33 min longer than manual plans (range: -17 to +91 min) when normalized to a calibration dose rate of 3.5 Gy/min. In terms of algorithm performance, the isocenter selection for all the presented plans was performed in less than 3 s, while the SDO was performed in an average of 215 min. PFX inverse planning can be performed using

Automated treatment planning for a dedicated multi-source intracranial radiosurgery treatment unit using projected gradient and grassfire algorithms

International Nuclear Information System (INIS)

Ghobadi, Kimia; Ghaffari, Hamid R.; Aleman, Dionne M.; Jaffray, David A.; Ruschin, Mark

2012-01-01

Purpose: The purpose of this work is to develop a framework to the inverse problem for radiosurgery treatment planning on the Gamma Knife ® Perfexion™ (PFX) for intracranial targets. Methods: The approach taken in the present study consists of two parts. First, a hybrid grassfire and sphere-packing algorithm is used to obtain shot positions (isocenters) based on the geometry of the target to be treated. For the selected isocenters, a sector duration optimization (SDO) model is used to optimize the duration of radiation delivery from each collimator size from each individual source bank. The SDO model is solved using a projected gradient algorithm. This approach has been retrospectively tested on seven manually planned clinical cases (comprising 11 lesions) including acoustic neuromas and brain metastases. Results: In terms of conformity and organ-at-risk (OAR) sparing, the quality of plans achieved with the inverse planning approach were, on average, improved compared to the manually generated plans. The mean difference in conformity index between inverse and forward plans was −0.12 (range: −0.27 to +0.03) and +0.08 (range: 0.00–0.17) for classic and Paddick definitions, respectively, favoring the inverse plans. The mean difference in volume receiving the prescribed dose (V 100 ) between forward and inverse plans was 0.2% (range: −2.4% to +2.0%). After plan renormalization for equivalent coverage (i.e., V 100 ), the mean difference in dose to 1 mm 3 of brainstem between forward and inverse plans was −0.24 Gy (range: −2.40 to +2.02 Gy) favoring the inverse plans. Beam-on time varied with the number of isocenters but for the most optimal plans was on average 33 min longer than manual plans (range: −17 to +91 min) when normalized to a calibration dose rate of 3.5 Gy/min. In terms of algorithm performance, the isocenter selection for all the presented plans was performed in less than 3 s, while the SDO was performed in an average of 215 min

Investigation of inversion polymorphisms in the human genome using principal components analysis.

Science.gov (United States)

Ma, Jianzhong; Amos, Christopher I

2012-01-01

Despite the significant advances made over the last few years in mapping inversions with the advent of paired-end sequencing approaches, our understanding of the prevalence and spectrum of inversions in the human genome has lagged behind other types of structural variants, mainly due to the lack of a cost-efficient method applicable to large-scale samples. We propose a novel method based on principal components analysis (PCA) to characterize inversion polymorphisms using high-density SNP genotype data. Our method applies to non-recurrent inversions for which recombination between the inverted and non-inverted segments in inversion heterozygotes is suppressed due to the loss of unbalanced gametes. Inside such an inversion region, an effect similar to population substructure is thus created: two distinct "populations" of inversion homozygotes of different orientations and their 1:1 admixture, namely the inversion heterozygotes. This kind of substructure can be readily detected by performing PCA locally in the inversion regions. Using simulations, we demonstrated that the proposed method can be used to detect and genotype inversion polymorphisms using unphased genotype data. We applied our method to the phase III HapMap data and inferred the inversion genotypes of known inversion polymorphisms at 8p23.1 and 17q21.31. These inversion genotypes were validated by comparing with literature results and by checking Mendelian consistency using the family data whenever available. Based on the PCA-approach, we also performed a preliminary genome-wide scan for inversions using the HapMap data, which resulted in 2040 candidate inversions, 169 of which overlapped with previously reported inversions. Our method can be readily applied to the abundant SNP data, and is expected to play an important role in developing human genome maps of inversions and exploring associations between inversions and susceptibility of diseases.

Multi-resolution inversion algorithm for the attenuated radon transform

KAUST Repository

Barbano, Paolo Emilio

2011-09-01

We present a FAST implementation of the Inverse Attenuated Radon Transform which incorporates accurate collimator response, as well as artifact rejection due to statistical noise and data corruption. This new reconstruction procedure is performed by combining a memory-efficient implementation of the analytical inversion formula (AIF [1], [2]) with a wavelet-based version of a recently discovered regularization technique [3]. The paper introduces all the main aspects of the new AIF, as well numerical experiments on real and simulated data. Those display a substantial improvement in reconstruction quality when compared to linear or iterative algorithms. © 2011 IEEE.

Planning of overhead contact lines and simulation of the pantograph running; Oberleitungsplanung und Simulation des Stromabnehmerlaufes

Energy Technology Data Exchange (ETDEWEB)

Hofbauer, Gerhard [ALPINE-ENERGIE Oesterreich GmbH, Linz (Austria); Hofbauer, Werner

2009-07-01

Using the software FLTG all planning steps for overhead contact lines can be carried out based on the parameters of the contact line type and the line data. Contact line supports and individual spans are presented graphically. The geometric interaction of pantograph and contact line can be simulated taking into account the pantograph type, its sway and the wind action. Thus, the suitability of a line for the interoperability of the transEuropean rail system can be demonstrated. (orig.)

Angle-domain inverse scattering migration/inversion in isotropic media

Science.gov (United States)

Li, Wuqun; Mao, Weijian; Li, Xuelei; Ouyang, Wei; Liang, Quan

2018-07-01

The classical seismic asymptotic inversion can be transformed into a problem of inversion of generalized Radon transform (GRT). In such methods, the combined parameters are linearly attached to the scattered wave-field by Born approximation and recovered by applying an inverse GRT operator to the scattered wave-field data. Typical GRT-style true-amplitude inversion procedure contains an amplitude compensation process after the weighted migration via dividing an illumination associated matrix whose elements are integrals of scattering angles. It is intuitional to some extent that performs the generalized linear inversion and the inversion of GRT together by this process for direct inversion. However, it is imprecise to carry out such operation when the illumination at the image point is limited, which easily leads to the inaccuracy and instability of the matrix. This paper formulates the GRT true-amplitude inversion framework in an angle-domain version, which naturally degrades the external integral term related to the illumination in the conventional case. We solve the linearized integral equation for combined parameters of different fixed scattering angle values. With this step, we obtain high-quality angle-domain common-image gathers (CIGs) in the migration loop which provide correct amplitude-versus-angle (AVA) behavior and reasonable illumination range for subsurface image points. Then we deal with the over-determined problem to solve each parameter in the combination by a standard optimization operation. The angle-domain GRT inversion method keeps away from calculating the inaccurate and unstable illumination matrix. Compared with the conventional method, the angle-domain method can obtain more accurate amplitude information and wider amplitude-preserved range. Several model tests demonstrate the effectiveness and practicability.

Recurrent Neural Network Approach Based on the Integral Representation of the Drazin Inverse.

Science.gov (United States)

Stanimirović, Predrag S; Živković, Ivan S; Wei, Yimin

2015-10-01

In this letter, we present the dynamical equation and corresponding artificial recurrent neural network for computing the Drazin inverse for arbitrary square real matrix, without any restriction on its eigenvalues. Conditions that ensure the stability of the defined recurrent neural network as well as its convergence toward the Drazin inverse are considered. Several illustrative examples present the results of computer simulations.

Towards Simulation of Custom Industrial Robots

OpenAIRE

Marcu, Cosmin; Robotin, Radu

2008-01-01

In order to create a simulator for custom industrial robots, it is very important to know the forward and inverse kinematics equations of the robot structure, the controller output data and the limitations of the robot mechanical components. In this paper we presented the steps for building a simulation program for a custom industrial robot. The first step was the robot modeling where we obtained the forward and inverse kinematics equations used as motion laws both for the simulated and for t...

Eliminating Inconsistencies in Simulation and Treatment Planning Orders in Radiation Therapy

International Nuclear Information System (INIS)

Santanam, Lakshmi; Brame, Ryan S.; Lindsey, Andrew; Dewees, Todd; Danieley, Jon; Labrash, Jason; Parikh, Parag; Bradley, Jeffrey; Zoberi, Imran; Michalski, Jeff; Mutic, Sasa

2013-01-01

Purpose: To identify deficiencies with simulation and treatment planning orders and to develop corrective measures to improve safety and quality. Methods and Materials: At Washington University, the DMAIIC formalism is used for process management, whereby the process is understood as comprising Define, Measure, Analyze, Improve, Implement, and Control activities. Two complementary tools were used to provide quantitative assessments: failure modes and effects analysis and reported event data. The events were classified by the user according to severity. The event rates (ie, number of events divided by the number of opportunities to generate an event) related to simulation and treatment plan orders were determined. Results: We analyzed event data from the period 2008-2009 to design an intelligent SIMulation and treatment PLanning Electronic (SIMPLE) order system. Before implementation of SIMPLE, event rates of 0.16 (420 of 2558) for a group of physicians that were subsequently used as a pilot group and 0.13 (787 of 6023) for all physicians were obtained. An interdisciplinary group evaluated and decided to replace the Microsoft Word-based form with a Web-based order system. This order system has mandatory fields and context-sensitive logic, an ability to create templates, and enables an automated process for communication of orders through an enterprise management system. After the implementation of the SIMPLE order, the event rate decreased to 0.09 (96 of 1001) for the pilot group and to 0.06 (145 of 2140) for all physicians (P<.0001). The average time to complete the SIMPLE form was 3 minutes, as compared with 7 minutes for the Word-based form. The number of severe events decreased from 10.7% (45 of 420) and 12.1% (96 of 787) to 6.2% (6 of 96) and 10.3% (15 of 145) for the pilot group and all physicians, respectively. Conclusions: There was a dramatic reduction in the total and the number of potentially severe events through use of the SIMPLE system. In addition

Combined Log Inventory and Process Simulation Models for the Planning and Control of Sawmill Operations

Science.gov (United States)

Guillermo A. Mendoza; Roger J. Meimban; Philip A. Araman; William G. Luppold

1991-01-01

A log inventory model and a real-time hardwood process simulation model were developed and combined into an integrated production planning and control system for hardwood sawmills. The log inventory model was designed to monitor and periodically update the status of the logs in the log yard. The process simulation model was designed to estimate various sawmill...

Protocol for quality control of scanners used in the simulation of radiotherapy treatment planning

International Nuclear Information System (INIS)

Yanes, Yaima; Alfonso, Rodolfo; Silvestre, Ileana

2009-01-01

Computed Tomography (CT) has become the tool fundamental imaging of modern radiation therapy, to locate targets and critical organs and dose planning. Tomographs used for these purposes require strict assurance program quality, which differs in many aspects of monitoring required for diagnostic use only with intention. The aim of this work has been the design and validation of a quality control protocol applicable to any TAC used for simulation, radiotherapy planning. (author)

Reconstructing the Hopfield network as an inverse Ising problem

International Nuclear Information System (INIS)

Huang Haiping

2010-01-01

We test four fast mean-field-type algorithms on Hopfield networks as an inverse Ising problem. The equilibrium behavior of Hopfield networks is simulated through Glauber dynamics. In the low-temperature regime, the simulated annealing technique is adopted. Although performances of these network reconstruction algorithms on the simulated network of spiking neurons are extensively studied recently, the analysis of Hopfield networks is lacking so far. For the Hopfield network, we found that, in the retrieval phase favored when the network wants to memory one of stored patterns, all the reconstruction algorithms fail to extract interactions within a desired accuracy, and the same failure occurs in the spin-glass phase where spurious minima show up, while in the paramagnetic phase, albeit unfavored during the retrieval dynamics, the algorithms work well to reconstruct the network itself. This implies that, as an inverse problem, the paramagnetic phase is conversely useful for reconstructing the network while the retrieval phase loses all the information about interactions in the network except for the case where only one pattern is stored. The performances of algorithms are studied with respect to the system size, memory load, and temperature; sample-to-sample fluctuations are also considered.

Geant4 simulation of ion chambers response to {sup 60}Co spectrum of LNMRI/IRD Shepherd 81-14D Radiator

Energy Technology Data Exchange (ETDEWEB)

Queiroz Filho, P.P.; Silva, C.N.M. da, E-mail: queiroz@ird.gov.br [Instituto de Radioproteção e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

2017-07-01

The National Ionizing Radiation Metrology Laboratory of the Radioprotection and Dosimetry Institute (LNMRI / IRD) has recently acquired a Shepherd 81-14D Radiator. In this work we simulate, using Geant4, the behavior with the inverse square law radiation of the distance for 3 models of PTW spherical chambers used in radioprotection, a relevant information to planning the measurements. We did the corrections for the attenuation and scattering in the air for each distance, where we used the {sup 60}Co spectrum simulated previously. (author)

Toward reduced transport errors in a high resolution urban CO2 inversion system

Directory of Open Access Journals (Sweden)

Aijun Deng

2017-05-01

Full Text Available We present a high-resolution atmospheric inversion system combining a Lagrangian Particle Dispersion Model (LPDM and the Weather Research and Forecasting model (WRF, and test the impact of assimilating meteorological observation on transport accuracy. A Four Dimensional Data Assimilation (FDDA technique continuously assimilates meteorological observations from various observing systems into the transport modeling system, and is coupled to the high resolution CO2 emission product Hestia to simulate the atmospheric mole fractions of CO2. For the Indianapolis Flux Experiment (INFLUX project, we evaluated the impact of assimilating different meteorological observation systems on the linearized adjoint solutions and the CO2 inverse fluxes estimated using observed CO2 mole fractions from 11 out of 12 communications towers over Indianapolis for the Sep.-Nov. 2013 period. While assimilating WMO surface measurements improved the simulated wind speed and direction, their impact on the planetary boundary layer (PBL was limited. Simulated PBL wind statistics improved significantly when assimilating upper-air observations from the commercial airline program Aircraft Communications Addressing and Reporting System (ACARS and continuous ground-based Doppler lidar wind observations. Wind direction mean absolute error (MAE decreased from 26 to 14 degrees and the wind speed MAE decreased from 2.0 to 1.2 m s–1, while the bias remains small in all configurations (< 6 degrees and 0.2 m s–1. Wind speed MAE and ME are larger in daytime than in nighttime. PBL depth MAE is reduced by ~10%, with little bias reduction. The inverse results indicate that the spatial distribution of CO2 inverse fluxes were affected by the model performance while the overall flux estimates changed little across WRF simulations when aggregated over the entire domain. Our results show that PBL wind observations are a potent tool for increasing the precision of urban meteorological reanalyses

Spin Polarization Inversion at Benzene-Absorbed Fe4N Surface

KAUST Repository

Zhang, Qian; Mi, Wenbo; Wang, Xiaocha; Wang, Xuhui

2015-01-01

We report a first-principle study on electronic structure and simulation of the spin-polarized scanning tunneling microscopy graphic of a benzene/Fe4N interface. Fe4N is a compound ferromagnet suitable for many spintronic applications. We found that, depending on the particular termination schemes and interface configurations, the spin polarization on the benzene surface shows a rich variety of properties ranging from cosine-type oscillation to polarization inversion. Spin-polarization inversion above benzene is resulting from the hybridizations between C pz and the out-of-plane d orbitals of Fe atom.

Inverse kinematics of a dual linear actuator pitch/roll heliostat

Science.gov (United States)

Freeman, Joshua; Shankar, Balakrishnan; Sundaram, Ganesh

2017-06-01

This work presents a simple, computationally efficient inverse kinematics solution for a pitch/roll heliostat using two linear actuators. The heliostat design and kinematics have been developed, modeled and tested using computer simulation software. A physical heliostat prototype was fabricated to validate the theoretical computations and data. Pitch/roll heliostats have numerous advantages including reduced cost potential and reduced space requirements, with a primary disadvantage being the significantly more complicated kinematics, which are solved here. Novel methods are applied to simplify the inverse kinematics problem which could be applied to other similar problems.

Spin Polarization Inversion at Benzene-Absorbed Fe4N Surface

KAUST Repository

Zhang, Qian

2015-05-27

We report a first-principle study on electronic structure and simulation of the spin-polarized scanning tunneling microscopy graphic of a benzene/Fe4N interface. Fe4N is a compound ferromagnet suitable for many spintronic applications. We found that, depending on the particular termination schemes and interface configurations, the spin polarization on the benzene surface shows a rich variety of properties ranging from cosine-type oscillation to polarization inversion. Spin-polarization inversion above benzene is resulting from the hybridizations between C pz and the out-of-plane d orbitals of Fe atom.

The Study on the Alteration of Simulated HLLW Glass in Aqueous Media by Inverse Gas Chromatography

International Nuclear Information System (INIS)

Zhang, Zhentao; Gan, Xueying; Yuan, Wenyi; Wang, Lei; Xing, Haiqing; Balard, Henri

2008-01-01

There exist webs of fissures inside the glass block accessible to underground water and theses fissures will influence the alteration of the glass significantly. It is very necessary to study the fissure surface properties of the glass under deep geological conditions. The alteration tests were conducted using the simulated high level radioactive glass powder immersed in Beishan (candidate disposal site) underground water with S/V ratio of 8000 m -1 at 150 deg. C and 90 deg. C for different periods. After immersion, the glass powder was filtered and dried at 120 deg. C for 3 hours. The surface properties of the dried glass powder were evaluated by inverse chromatography. The results showed that the specific surface area of the glass increases abruptly at the beginning of immersion and then increase slowly afterwards. At higher immersion temperature, the secondary phase is condensing crystals; at the lower immersion temperature, the secondary phases were loosely 'islands' with cracks or fissures. (authors)

Kinematic simulation and analysis of robot based on MATLAB

Science.gov (United States)

Liao, Shuhua; Li, Jiong

2018-03-01

The history of industrial automation is characterized by quick update technology, however, without a doubt, the industrial robot is a kind of special equipment. With the help of MATLAB matrix and drawing capacity in the MATLAB environment each link coordinate system set up by using the d-h parameters method and equation of motion of the structure. Robotics, Toolbox programming Toolbox and GUIDE to the joint application is the analysis of inverse kinematics and path planning and simulation, preliminary solve the problem of college students the car mechanical arm positioning theory, so as to achieve the aim of reservation.

Generalization of the Rabi population inversion dynamics in the sub-one-cycle pulse limit

International Nuclear Information System (INIS)

Doslic, N.

2006-01-01

We consider the population inversion in a two-level system generated by a sub-one-cycle pulse excitation. Specifically, we explore the effect that the time derivative of the pulse envelope has on the Rabi dynamics. Our analysis is based on a combination of analytical, perturbative, and nonperturbative treatments and is complemented by numerical simulations. We find a shortening of the Rabi inversion period and show that complete inversion is unobtainable under resonant, ultrashort pulse conditions. The impact of nonresonant and carrier-envelope phase-dependent effects on the dynamics of two-level and multilevel systems is studied numerically, and conditions for complete population inversion are derived

Final Report: Improved Site Characterization And Storage Prediction Through Stochastic Inversion Of Time-Lapse Geophysical And Geochemical Data

Energy Technology Data Exchange (ETDEWEB)

Ramirez, A; Mcnab, W; Hao, Y; White, D; Johnson, J

2011-04-14

During the last months of this project, our project activities have concentrated on four areas: (1) performing a stochastic inversion of pattern 16 seismic data to deduce reservoir bulk/shear moduli and density; the need for this inversion was not anticipated in the original scope of work, (2) performing a stochastic inversion of pattern 16 seismic data to deduce reservoir porosity and permeability, (3) complete the software needed to perform geochemical inversions and (4) use the software to perform stochastic inversion of aqueous chemistry data to deduce mineral volume fractions. This report builds on work described in progress reports previously submitted (Ramirez et al., 2009, 2010, 2011 - reports fulfilled the requirements of deliverables D1-D4) and fulfills deliverable D5: Field-based single-pattern simulations work product. The main challenge with our stochastic inversion approach is its large computational expense, even for single reservoir patterns. We dedicated a significant level of effort to improve computational efficiency but inversions involving multiple patterns were still intractable by project's end. As a result, we were unable to fulfill Deliverable D6: Field-based multi-pattern simulations work product.

Three-dimensional inversion of multisource array electromagnetic data

Science.gov (United States)

Tartaras, Efthimios

Three-dimensional (3-D) inversion is increasingly important for the correct interpretation of geophysical data sets in complex environments. To this effect, several approximate solutions have been developed that allow the construction of relatively fast inversion schemes. One such method that is fast and provides satisfactory accuracy is the quasi-linear (QL) approximation. It has, however, the drawback that it is source-dependent and, therefore, impractical in situations where multiple transmitters in different positions are employed. I have, therefore, developed a localized form of the QL approximation that is source-independent. This so-called localized quasi-linear (LQL) approximation can have a scalar, a diagonal, or a full tensor form. Numerical examples of its comparison with the full integral equation solution, the Born approximation, and the original QL approximation are given. The objective behind developing this approximation is to use it in a fast 3-D inversion scheme appropriate for multisource array data such as those collected in airborne surveys, cross-well logging, and other similar geophysical applications. I have developed such an inversion scheme using the scalar and diagonal LQL approximation. It reduces the original nonlinear inverse electromagnetic (EM) problem to three linear inverse problems. The first of these problems is solved using a weighted regularized linear conjugate gradient method, whereas the last two are solved in the least squares sense. The algorithm I developed provides the option of obtaining either smooth or focused inversion images. I have applied the 3-D LQL inversion to synthetic 3-D EM data that simulate a helicopter-borne survey over different earth models. The results demonstrate the stability and efficiency of the method and show that the LQL approximation can be a practical solution to the problem of 3-D inversion of multisource array frequency-domain EM data. I have also applied the method to helicopter-borne EM

Treatment planning for laser-accelerated very-high energy electrons

International Nuclear Information System (INIS)

Fuchs, T; Szymanowski, H; Oelfke, U; Glinec, Y; Rechatin, C; Faure, J; Malka, V

2009-01-01

In recent experiments, quasi-monoenergetic and well-collimated very-high energy electron (VHEE) beams were obtained by laser-plasma accelerators. We investigate their potential use for radiation therapy. Monte Carlo simulations are used to study the influence of the experimental characteristics such as beam energy, energy spread and initial angular distribution on the dose distributions. It is found that magnetic focusing of the electron beam improves the lateral penumbra. The dosimetric properties of the laser-accelerated VHEE beams are implemented in our inverse treatment planning system for intensity-modulated treatments. The influence of the beam characteristics on the quality of a prostate treatment plan is evaluated. In comparison to a clinically approved 6 MV IMRT photon plan, a better target coverage is achieved. The quality of the sparing of organs at risk is found to be dependent on the depth. The bladder and rectum are better protected due to the sharp lateral penumbra at low depths, whereas the femoral heads receive a larger dose because of the large scattering amplitude at larger depths.

Multi-period multi-objective electricity generation expansion planning problem with Monte-Carlo simulation

Energy Technology Data Exchange (ETDEWEB)

Tekiner, Hatice [Industrial Engineering, College of Engineering and Natural Sciences, Istanbul Sehir University, 2 Ahmet Bayman Rd, Istanbul (Turkey); Coit, David W. [Department of Industrial and Systems Engineering, Rutgers University, 96 Frelinghuysen Rd., Piscataway, NJ (United States); Felder, Frank A. [Edward J. Bloustein School of Planning and Public Policy, Rutgers University, Piscataway, NJ (United States)

2010-12-15

A new approach to the electricity generation expansion problem is proposed to minimize simultaneously multiple objectives, such as cost and air emissions, including CO{sub 2} and NO{sub x}, over a long term planning horizon. In this problem, system expansion decisions are made to select the type of power generation, such as coal, nuclear, wind, etc., where the new generation asset should be located, and at which time period expansion should take place. We are able to find a Pareto front for the multi-objective generation expansion planning problem that explicitly considers availability of the system components over the planning horizon and operational dispatching decisions. Monte-Carlo simulation is used to generate numerous scenarios based on the component availabilities and anticipated demand for energy. The problem is then formulated as a mixed integer linear program, and optimal solutions are found based on the simulated scenarios with a combined objective function considering the multiple problem objectives. The different objectives are combined using dimensionless weights and a Pareto front can be determined by varying these weights. The mathematical model is demonstrated on an example problem with interesting results indicating how expansion decisions vary depending on whether minimizing cost or minimizing greenhouse gas emissions or pollutants is given higher priority. (author)

Preoperative surgical planning and simulation of complex cranial base tumors in virtual reality

Institute of Scientific and Technical Information of China (English)

YI Zhi-qiang; LI Liang; MO Da-peng; ZHANG Jia-yong; ZHANG Yang; BAO Sheng-de

2008-01-01

@@ The extremely complex anatomic relationships among bone,tumor,blood vessels and cranial nerves remains a big challenge for cranial base tumor surgery.Therefore.a good understanding of the patient specific anatomy and a preoperative planning are helpful and crocial for the neurosurgeons.Three dimensional (3-D) visualization of various imaging techniques have been widely explored to enhance the comprehension of volumetric data for surgical planning.1 We used the Destroscope Virtual Reality (VR) System (Singapore,Volume Interaction Pte Ltd,software:RadioDexterTM 1.0) to optimize preoperative plan in the complex cranial base tumors.This system uses patient-specific,coregistered,fused radiology data sets that may be viewed stereoscopically and can be manipulated in a virtual reality environment.This article describes our experience with the Destroscope VR system in preoperative surgical planning and simulation for 5 patients with complex cranial base tumors and evaluates the clinical usefulness of this system.

A bi-level integrated generation-transmission planning model incorporating the impacts of demand response by operation simulation

International Nuclear Information System (INIS)

Zhang, Ning; Hu, Zhaoguang; Springer, Cecilia; Li, Yanning; Shen, Bo

2016-01-01

Highlights: • We put forward a novel bi-level integrated power system planning model. • Generation expansion planning and transmission expansion planning are combined. • The effects of two sorts of demand response in reducing peak load are considered. • Operation simulation is conducted to reflect the actual effects of demand response. • The interactions between the two levels can guarantee a reasonably optimal result. - Abstract: If all the resources in power supply side, transmission part, and power demand side are considered together, the optimal expansion scheme from the perspective of the whole system can be achieved. In this paper, generation expansion planning and transmission expansion planning are combined into one model. Moreover, the effects of demand response in reducing peak load are taken into account in the planning model, which can cut back the generation expansion capacity and transmission expansion capacity. Existing approaches to considering demand response for planning tend to overestimate the impacts of demand response on peak load reduction. These approaches usually focus on power reduction at the moment of peak load without considering the situations in which load demand at another moment may unexpectedly become the new peak load due to demand response. These situations are analyzed in this paper. Accordingly, a novel approach to incorporating demand response in a planning model is proposed. A modified unit commitment model with demand response is utilized. The planning model is thereby a bi-level model with interactions between generation-transmission expansion planning and operation simulation to reflect the actual effects of demand response and find the reasonably optimal planning result.

The Traverse Planning Process for the Drats 2010 Analog Field Simulations

Science.gov (United States)

Horz, Friedrich; Gruener, John; Lofgren, Gary; Skinner, James A., Jr.; Graf, Jodi; Seibert, Marc

2011-01-01

Traverse planning concentrates on optimizing the science return within the overall objectives of planetary surface missions or their analog field simulations. Such simulations were conducted in the San Francisco Volcanic Field, northern Arizona, from Aug. 26 to Sept 17, 2010 and involved some 200 individuals in the field, with some 40 geoscientists composing the science team. The purpose of these Desert Research and Technology Studies (DRATS) is to exercise and evaluate developmental hardware, software and operational concepts in a mission-like, fully-integrated, setting under the direction of an onsite Mobile Mission Control Center(MMCC). DRATS 2010 focused on the simultaneous operation of 2 rovers, a historic first. Each vehicle was manned by an astronaut-commander and an experienced field geologist. Having 2 rovers and crews in the field mandated substantially more complex science and mission control operations compared to the single rover DRATS tests of 2008 and 2009, or the Apollo lunar missions. For instance, the science support function was distributed over 2 "back rooms", one for each rover, with both "tactical" teams operating independently and simultaneously during the actual traverses. Synthesis and integration of the daily findings and forward planning for the next day(s) was accomplished overnight by yet another "strategic" science team.

Spatial Variability in Column CO2 Inferred from High Resolution GEOS-5 Global Model Simulations: Implications for Remote Sensing and Inversions

Science.gov (United States)

Ott, L.; Putman, B.; Collatz, J.; Gregg, W.

2012-01-01

Column CO2 observations from current and future remote sensing missions represent a major advancement in our understanding of the carbon cycle and are expected to help constrain source and sink distributions. However, data assimilation and inversion methods are challenged by the difference in scale of models and observations. OCO-2 footprints represent an area of several square kilometers while NASA s future ASCENDS lidar mission is likely to have an even smaller footprint. In contrast, the resolution of models used in global inversions are typically hundreds of kilometers wide and often cover areas that include combinations of land, ocean and coastal areas and areas of significant topographic, land cover, and population density variations. To improve understanding of scales of atmospheric CO2 variability and representativeness of satellite observations, we will present results from a global, 10-km simulation of meteorology and atmospheric CO2 distributions performed using NASA s GEOS-5 general circulation model. This resolution, typical of mesoscale atmospheric models, represents an order of magnitude increase in resolution over typical global simulations of atmospheric composition allowing new insight into small scale CO2 variations across a wide range of surface flux and meteorological conditions. The simulation includes high resolution flux datasets provided by NASA s Carbon Monitoring System Flux Pilot Project at half degree resolution that have been down-scaled to 10-km using remote sensing datasets. Probability distribution functions are calculated over larger areas more typical of global models (100-400 km) to characterize subgrid-scale variability in these models. Particular emphasis is placed on coastal regions and regions containing megacities and fires to evaluate the ability of coarse resolution models to represent these small scale features. Additionally, model output are sampled using averaging kernels characteristic of OCO-2 and ASCENDS measurement

Forward planning

International Nuclear Information System (INIS)

Fontenla, D.P.

2008-01-01

By definition, forward planning is a process where input consists of conditions on beam configurations and parameters and output consists of dose distributions on target and critical structures, in contrast to inverse planning, where the opposite is true. For forward planning IMRT, criteria are as follows: (i) Plans created as an extension of standard 3D conformational planning; (ii) No significant increase in the complexity of the treatment planning or treatment delivery process; (3) Treatment verification using standard QA procedures; and process consists of the following steps: (i) Create a standard 3D conformational treatment plan; (ii) Copy one of the existing beams; (iii) Create control points: design new beam segments, blocking high dose areas; (iv) Repeat for all beams; (v) Re-compute dose; and (vi) Adjust control points weights to achieve desired dose distribution. A detailed exposition, with many clinical examples, is given for the breast, lung, and brain (P.A.)

Generalizable open source urban water portfolio simulation framework demonstrated using a multi-objective risk-based planning benchmark problem.

Science.gov (United States)

Trindade, B. C.; Reed, P. M.

2017-12-01

The growing access and reduced cost for computing power in recent years has promoted rapid development and application of multi-objective water supply portfolio planning. As this trend continues there is a pressing need for flexible risk-based simulation frameworks and improved algorithm benchmarking for emerging classes of water supply planning and management problems. This work contributes the Water Utilities Management and Planning (WUMP) model: a generalizable and open source simulation framework designed to capture how water utilities can minimize operational and financial risks by regionally coordinating planning and management choices, i.e. making more efficient and coordinated use of restrictions, water transfers and financial hedging combined with possible construction of new infrastructure. We introduce the WUMP simulation framework as part of a new multi-objective benchmark problem for planning and management of regionally integrated water utility companies. In this problem, a group of fictitious water utilities seek to balance the use of the mentioned reliability driven actions (e.g., restrictions, water transfers and infrastructure pathways) and their inherent financial risks. Several traits of this problem make it ideal for a benchmark problem, namely the presence of (1) strong non-linearities and discontinuities in the Pareto front caused by the step-wise nature of the decision making formulation and by the abrupt addition of storage through infrastructure construction, (2) noise due to the stochastic nature of the streamflows and water demands, and (3) non-separability resulting from the cooperative formulation of the problem, in which decisions made by stakeholder may substantially impact others. Both the open source WUMP simulation framework and its demonstration in a challenging benchmarking example hold value for promoting broader advances in urban water supply portfolio planning for regions confronting change.

Inverse Theory for Petroleum Reservoir Characterization and History Matching

Science.gov (United States)

Oliver, Dean S.; Reynolds, Albert C.; Liu, Ning

This book is a guide to the use of inverse theory for estimation and conditional simulation of flow and transport parameters in porous media. It describes the theory and practice of estimating properties of underground petroleum reservoirs from measurements of flow in wells, and it explains how to characterize the uncertainty in such estimates. Early chapters present the reader with the necessary background in inverse theory, probability and spatial statistics. The book demonstrates how to calculate sensitivity coefficients and the linearized relationship between models and production data. It also shows how to develop iterative methods for generating estimates and conditional realizations. The text is written for researchers and graduates in petroleum engineering and groundwater hydrology and can be used as a textbook for advanced courses on inverse theory in petroleum engineering. It includes many worked examples to demonstrate the methodologies and a selection of exercises.

A Robust Inversion Algorithm for Surface Leaf and Soil Temperatures Using the Vegetation Clumping Index

Directory of Open Access Journals (Sweden)

Zunjian Bian

2017-07-01

Full Text Available The inversion of land surface component temperatures is an essential source of information for mapping heat fluxes and the angular normalization of thermal infrared (TIR observations. Leaf and soil temperatures can be retrieved using multiple-view-angle TIR observations. In a satellite-scale pixel, the clumping effect of vegetation is usually present, but it is not completely considered during the inversion process. Therefore, we introduced a simple inversion procedure that uses gap frequency with a clumping index (GCI for leaf and soil temperatures over both crop and forest canopies. Simulated datasets corresponding to turbid vegetation, regularly planted crops and randomly distributed forest were generated using a radiosity model and were used to test the proposed inversion algorithm. The results indicated that the GCI algorithm performed well for both crop and forest canopies, with root mean squared errors of less than 1.0 °C against simulated values. The proposed inversion algorithm was also validated using measured datasets over orchard, maize and wheat canopies. Similar results were achieved, demonstrating that using the clumping index can improve inversion results. In all evaluations, we recommend using the GCI algorithm as a foundation for future satellite-based applications due to its straightforward form and robust performance for both crop and forest canopies using the vegetation clumping index.

Displacement Parameter Inversion for a Novel Electromagnetic Underground Displacement Sensor

Directory of Open Access Journals (Sweden)

Nanying Shentu

2014-05-01

Full Text Available Underground displacement monitoring is an effective method to explore deep into rock and soil masses for execution of subsurface displacement measurements. It is not only an important means of geological hazards prediction and forecasting, but also a forefront, hot and sophisticated subject in current geological disaster monitoring. In previous research, the authors had designed a novel electromagnetic underground horizontal displacement sensor (called the H-type sensor by combining basic electromagnetic induction principles with modern sensing techniques and established a mutual voltage measurement theoretical model called the Equation-based Equivalent Loop Approach (EELA. Based on that work, this paper presents an underground displacement inversion approach named “EELA forward modeling-approximate inversion method”. Combining the EELA forward simulation approach with the approximate optimization inversion theory, it can deduce the underground horizontal displacement through parameter inversion of the H-type sensor. Comprehensive and comparative studies have been conducted between the experimentally measured and theoretically inversed values of horizontal displacement under counterpart conditions. The results show when the measured horizontal displacements are in the 0–100 mm range, the horizontal displacement inversion discrepancy is generally tested to be less than 3 mm under varied tilt angles and initial axial distances conditions, which indicates that our proposed parameter inversion method can predict underground horizontal displacement measurements effectively and robustly for the H-type sensor and the technique is applicable for practical geo-engineering applications.

A new optimization method using a compressed sensing inspired solver for real-time LDR-brachytherapy treatment planning

International Nuclear Information System (INIS)

Guthier, C; Aschenbrenner, K P; Buergy, D; Ehmann, M; Wenz, F; Hesser, J W

2015-01-01

This work discusses a novel strategy for inverse planning in low dose rate brachytherapy. It applies the idea of compressed sensing to the problem of inverse treatment planning and a new solver for this formulation is developed. An inverse planning algorithm was developed incorporating brachytherapy dose calculation methods as recommended by AAPM TG-43. For optimization of the functional a new variant of a matching pursuit type solver is presented. The results are compared with current state-of-the-art inverse treatment planning algorithms by means of real prostate cancer patient data. The novel strategy outperforms the best state-of-the-art methods in speed, while achieving comparable quality. It is able to find solutions with comparable values for the objective function and it achieves these results within a few microseconds, being up to 542 times faster than competing state-of-the-art strategies, allowing real-time treatment planning. The sparse solution of inverse brachytherapy planning achieved with methods from compressed sensing is a new paradigm for optimization in medical physics. Through the sparsity of required needles and seeds identified by this method, the cost of intervention may be reduced. (paper)

A new optimization method using a compressed sensing inspired solver for real-time LDR-brachytherapy treatment planning

Science.gov (United States)

Guthier, C.; Aschenbrenner, K. P.; Buergy, D.; Ehmann, M.; Wenz, F.; Hesser, J. W.

2015-03-01

This work discusses a novel strategy for inverse planning in low dose rate brachytherapy. It applies the idea of compressed sensing to the problem of inverse treatment planning and a new solver for this formulation is developed. An inverse planning algorithm was developed incorporating brachytherapy dose calculation methods as recommended by AAPM TG-43. For optimization of the functional a new variant of a matching pursuit type solver is presented. The results are compared with current state-of-the-art inverse treatment planning algorithms by means of real prostate cancer patient data. The novel strategy outperforms the best state-of-the-art methods in speed, while achieving comparable quality. It is able to find solutions with comparable values for the objective function and it achieves these results within a few microseconds, being up to 542 times faster than competing state-of-the-art strategies, allowing real-time treatment planning. The sparse solution of inverse brachytherapy planning achieved with methods from compressed sensing is a new paradigm for optimization in medical physics. Through the sparsity of required needles and seeds identified by this method, the cost of intervention may be reduced.

Inversions

Science.gov (United States)

Brown, Malcolm

2009-01-01

Inversions are fascinating phenomena. They are reversals of the normal or expected order. They occur across a wide variety of contexts. What do inversions have to do with learning spaces? The author suggests that they are a useful metaphor for the process that is unfolding in higher education with respect to education. On the basis of…

Inverse thermal analysis method to study solidification in cast iron

DEFF Research Database (Denmark)

Dioszegi, Atilla; Hattel, Jesper

2004-01-01

Solidification modelling of cast metals is widely used to predict final properties in cast components. Accurate models necessitate good knowledge of the solidification behaviour. The present study includes a re-examination of the Fourier thermal analysis method. This involves an inverse numerical...... solution of a 1-dimensional heat transfer problem connected to solidification of cast alloys. In the analysis, the relation between the thermal state and the fraction solid of the metal is evaluated by a numerical method. This method contains an iteration algorithm controlled by an under relaxation term...... inverse thermal analysis was tested on both experimental and simulated data....

Magneto-optical extinction trend inversion in ferrofluids

Energy Technology Data Exchange (ETDEWEB)

Shulyma, S.I., E-mail: kiw_88@mail.ru; Tanygin, B.M., E-mail: b.m.tanygin@gmail.com; Kovalenko, V.F.; Petrychuk, M.V.

2016-10-15

Effects of pulse magnetic field on the optical transmission properties of thin ferrofluid (FF) layers were experimentally investigated. It was observed that, under an influence of an external uniform magnetic field, pulses applied to the samples surfaces in normal direction decrease the optical transmission with further returning it to its original state, even before the end of the field pulse. The dependencies of the observed effects on the magnetic pulse magnitude and the samples thickness were investigated. The experimental results are explained using FF columnar aggregates growth and lateral coalescence under influence of a magnetic field, leading to a light scattering type Rayleigh-to-Mie transition. Further evolution of this process comes to a geometrical optics scale and respective macroscopic observable opaque FF columnar aggregates emergence. These changes of optical transmission are non-monotonic during the magnetic field pulse duration with minimal value in the case of Mie scattering, which is known as a magneto-optical extinction trend inversion. The residual inversion was detected after the external magnetic field pulse falling edge. Using molecular dynamics simulation, we showed that a homogeneous external magnetic field is enough for the formation of columnar aggregates and their fusion. The results clarify the known Li theory (Li et al., 2004, 2007), implying an inhomogeneous field as a required prerequisite for the magneto-optical extinction trend inversion phenomenon. - Highlights: • Ferrofluid columnar aggregates have been observed in a homogeneous magnetic field. • Magneto-optical extinction trend inversion is related to the Mie light scattering. • Crucial role of columnar aggregates growth and lateral coalescence has been revealed. • Residual extinction trend inversion was observed after the field switch off.

Magneto-optical extinction trend inversion in ferrofluids

International Nuclear Information System (INIS)

Shulyma, S.I.; Tanygin, B.M.; Kovalenko, V.F.; Petrychuk, M.V.

2016-01-01

Effects of pulse magnetic field on the optical transmission properties of thin ferrofluid (FF) layers were experimentally investigated. It was observed that, under an influence of an external uniform magnetic field, pulses applied to the samples surfaces in normal direction decrease the optical transmission with further returning it to its original state, even before the end of the field pulse. The dependencies of the observed effects on the magnetic pulse magnitude and the samples thickness were investigated. The experimental results are explained using FF columnar aggregates growth and lateral coalescence under influence of a magnetic field, leading to a light scattering type Rayleigh-to-Mie transition. Further evolution of this process comes to a geometrical optics scale and respective macroscopic observable opaque FF columnar aggregates emergence. These changes of optical transmission are non-monotonic during the magnetic field pulse duration with minimal value in the case of Mie scattering, which is known as a magneto-optical extinction trend inversion. The residual inversion was detected after the external magnetic field pulse falling edge. Using molecular dynamics simulation, we showed that a homogeneous external magnetic field is enough for the formation of columnar aggregates and their fusion. The results clarify the known Li theory (Li et al., 2004, 2007), implying an inhomogeneous field as a required prerequisite for the magneto-optical extinction trend inversion phenomenon. - Highlights: • Ferrofluid columnar aggregates have been observed in a homogeneous magnetic field. • Magneto-optical extinction trend inversion is related to the Mie light scattering. • Crucial role of columnar aggregates growth and lateral coalescence has been revealed. • Residual extinction trend inversion was observed after the field switch off.

How inverse solver technologies can support die face development and process planning in the automotive industry

Science.gov (United States)

Huhn, Stefan; Peeling, Derek; Burkart, Maximilian

2017-10-01

With the availability of die face design tools and incremental solver technologies to provide detailed forming feasibility results in a timely fashion, the use of inverse solver technologies and resulting process improvements during the product development process of stamped parts often is underestimated. This paper presents some applications of inverse technologies that are currently used in the automotive industry to streamline the product development process and greatly increase the quality of a developed process and the resulting product. The first focus is on the so-called target strain technology. Application examples will show how inverse forming analysis can be applied to support the process engineer during the development of a die face geometry for Class `A' panels. The drawing process is greatly affected by the die face design and the process designer has to ensure that the resulting drawn panel will meet specific requirements regarding surface quality and a minimum strain distribution to ensure dent resistance. The target strain technology provides almost immediate feedback to the process engineer during the die face design process if a specific change of the die face design will help to achieve these specific requirements or will be counterproductive. The paper will further show how an optimization of the material flow can be achieved through the use of a newly developed technology called Sculptured Die Face (SDF). The die face generation in SDF is more suited to be used in optimization loops than any other conventional die face design technology based on cross section design. A second focus in this paper is on the use of inverse solver technologies for secondary forming operations. The paper will show how the application of inverse technology can be used to accurately and quickly develop trim lines on simple as well as on complex support geometries.

Estimation of physical properties of laminated composites via the method of inverse vibration problem

Energy Technology Data Exchange (ETDEWEB)

Balci, Murat [Dept. of Mechanical Engineering, Bayburt University, Bayburt (Turkmenistan); Gundogdu, Omer [Dept. of Mechanical Engineering, Ataturk University, Erzurum (Turkmenistan)

2017-01-15

In this study, estimation of some physical properties of a laminated composite plate was conducted via the inverse vibration problem. Laminated composite plate was modelled and simulated to obtain vibration responses for different length-to-thickness ratio in ANSYS. Furthermore, a numerical finite element model was developed for the laminated composite utilizing the Kirchhoff plate theory and programmed in MATLAB for simulations. Optimizing the difference between these two vibration responses, inverse vibration problem was solved to obtain some of the physical properties of the laminated composite using genetic algorithms. The estimated parameters are compared with the theoretical results, and a very good correspondence was observed.

Estimation of physical properties of laminated composites via the method of inverse vibration problem

International Nuclear Information System (INIS)

Balci, Murat; Gundogdu, Omer

2017-01-01

In this study, estimation of some physical properties of a laminated composite plate was conducted via the inverse vibration problem. Laminated composite plate was modelled and simulated to obtain vibration responses for different length-to-thickness ratio in ANSYS. Furthermore, a numerical finite element model was developed for the laminated composite utilizing the Kirchhoff plate theory and programmed in MATLAB for simulations. Optimizing the difference between these two vibration responses, inverse vibration problem was solved to obtain some of the physical properties of the laminated composite using genetic algorithms. The estimated parameters are compared with the theoretical results, and a very good correspondence was observed

Inverse kinetics equations for on line measurement of reactivity using personal computer

International Nuclear Information System (INIS)

Ratemi, Wajdi; El Gadamsi, Walied; Beleid, Abdul Kariem

1993-01-01

Computer with their astonishing speed of calculations along with their easy connection to real systems, are very appropriate for digital measurements of real system variables. In the nuclear industry, such computer application will produce compact control rooms of real power plants, where information and results display can be obtained through push button concept. In our study, we use two personal computers for the purpose of simulation and measurement. One of them is used as a digital simulator to a real reactor, where we effectively simulate the reactor power through a cross talk network. The computed power is passed at certain chosen sampling time to the other computer. The purpose of the other computer is to use the inverse kinetics equations to calculate the reactivity parameter based on the received power and then it performs on line display of the power curve and the reactivity curve using color graphics. In this study, we use the one group version of the inverse kinetics algorithm which can easily be extended to larger group version. The language of programming used in Turbo BASIC, which is very comparable, in terms of efficiency, to FORTRAN language, besides its effective graphics routines. With the use of the extended version of the Inverse Kinetics algorithm, we can effectively apply this techniques of measurement for the purpose of on line display of the reactivity of the Tajoura Research Reactor. (author)

Inverse modelling of European CH4 emissions during 2006-2012 using different inverse models and reassessed atmospheric observations

Science.gov (United States)

Bergamaschi, Peter; Karstens, Ute; Manning, Alistair J.; Saunois, Marielle; Tsuruta, Aki; Berchet, Antoine; Vermeulen, Alexander T.; Arnold, Tim; Janssens-Maenhout, Greet; Hammer, Samuel; Levin, Ingeborg; Schmidt, Martina; Ramonet, Michel; Lopez, Morgan; Lavric, Jost; Aalto, Tuula; Chen, Huilin; Feist, Dietrich G.; Gerbig, Christoph; Haszpra, László; Hermansen, Ove; Manca, Giovanni; Moncrieff, John; Meinhardt, Frank; Necki, Jaroslaw; Galkowski, Michal; O'Doherty, Simon; Paramonova, Nina; Scheeren, Hubertus A.; Steinbacher, Martin; Dlugokencky, Ed

2018-01-01

We present inverse modelling (top down) estimates of European methane (CH4) emissions for 2006-2012 based on a new quality-controlled and harmonised in situ data set from 18 European atmospheric monitoring stations. We applied an ensemble of seven inverse models and performed four inversion experiments, investigating the impact of different sets of stations and the use of a priori information on emissions. The inverse models infer total CH4 emissions of 26.8 (20.2-29.7) Tg CH4 yr-1 (mean, 10th and 90th percentiles from all inversions) for the EU-28 for 2006-2012 from the four inversion experiments. For comparison, total anthropogenic CH4 emissions reported to UNFCCC (bottom up, based on statistical data and emissions factors) amount to only 21.3 Tg CH4 yr-1 (2006) to 18.8 Tg CH4 yr-1 (2012). A potential explanation for the higher range of top-down estimates compared to bottom-up inventories could be the contribution from natural sources, such as peatlands, wetlands, and wet soils. Based on seven different wetland inventories from the Wetland and Wetland CH4 Inter-comparison of Models Project (WETCHIMP), total wetland emissions of 4.3 (2.3-8.2) Tg CH4 yr-1 from the EU-28 are estimated. The hypothesis of significant natural emissions is supported by the finding that several inverse models yield significant seasonal cycles of derived CH4 emissions with maxima in summer, while anthropogenic CH4 emissions are assumed to have much lower seasonal variability. Taking into account the wetland emissions from the WETCHIMP ensemble, the top-down estimates are broadly consistent with the sum of anthropogenic and natural bottom-up inventories. However, the contribution of natural sources and their regional distribution remain rather uncertain. Furthermore, we investigate potential biases in the inverse models by comparison with regular aircraft profiles at four European sites and with vertical profiles obtained during the Infrastructure for Measurement of the European Carbon

Preoperative planning with three-dimensional reconstruction of patient's anatomy, rapid prototyping and simulation for endoscopic mitral valve repair.

Science.gov (United States)

Sardari Nia, Peyman; Heuts, Samuel; Daemen, Jean; Luyten, Peter; Vainer, Jindrich; Hoorntje, Jan; Cheriex, Emile; Maessen, Jos

2017-02-01

Mitral valve repair performed by an experienced surgeon is superior to mitral valve replacement for degenerative mitral valve disease; however, many surgeons are still deterred from adapting this procedure because of a steep learning curve. Simulation-based training and planning could improve the surgical performance and reduce the learning curve. The aim of this study was to develop a patient-specific simulation for mitral valve repair and provide a proof of concept of personalized medicine in a patient prospectively planned for mitral valve surgery. A 65-year old male with severe symptomatic mitral valve regurgitation was referred to our mitral valve heart team. On the basis of three-dimensional (3D) transoesophageal echocardiography and computed tomography, 3D reconstructions of the patient's anatomy were constructed. By navigating through these reconstructions, the repair options and surgical access were chosen (minimally invasive repair). Using rapid prototyping and negative mould fabrication, we developed a process to cast a patient-specific mitral valve silicone replica for preoperative repair in a high-fidelity simulator. Mitral valve and negative mould were printed in systole to capture the pathology when the valve closes. A patient-specific mitral valve silicone replica was casted and mounted in the simulator. All repair techniques could be performed in the simulator to choose the best repair strategy. As the valve was printed in systole, no special testing other than adjusting the coaptation area was required. Subsequently, the patient was operated, mitral valve pathology was validated and repair was successfully done as in the simulation. The patient-specific simulation and planning could be applied for surgical training, starting the (minimally invasive) mitral valve repair programme, planning of complex cases and the evaluation of new interventional techniques. The personalized medicine could be a possible pathway towards enhancing reproducibility

An inverse problem approach to pattern recognition in industry

Directory of Open Access Journals (Sweden)

Ali Sever

2015-01-01

Full Text Available Many works have shown strong connections between learning and regularization techniques for ill-posed inverse problems. A careful analysis shows that a rigorous connection between learning and regularization for inverse problem is not straightforward. In this study, pattern recognition will be viewed as an ill-posed inverse problem and applications of methods from the theory of inverse problems to pattern recognition are studied. A new learning algorithm derived from a well-known regularization model is generated and applied to the task of reconstruction of an inhomogeneous object as pattern recognition. Particularly, it is demonstrated that pattern recognition can be reformulated in terms of inverse problems defined by a Riesz-type kernel. This reformulation can be employed to design a learning algorithm based on a numerical solution of a system of linear equations. Finally, numerical experiments have been carried out with synthetic experimental data considering a reasonable level of noise. Good recoveries have been achieved with this methodology, and the results of these simulations are compatible with the existing methods. The comparison results show that the Regularization-based learning algorithm (RBA obtains a promising performance on the majority of the test problems. In prospects, this method can be used for the creation of automated systems for diagnostics, testing, and control in various fields of scientific and applied research, as well as in industry.

Prostate Dose Escalation by a Innovative Inverse Planning-Driven IMRT

Science.gov (United States)

2008-11-01

sessions for the parotid gland, optic track, and the temporal lobe when they were in extreme proximity with the PTV. The comparisons of the dose...gross target volume; L = left; OC = optic chiasm; ON = optic nerve; PARO = parotid gland; pCT = planning computed tomography; PTV = planning target...chiasm/nerves, optic lens, left parotid , larynx and spinal cord. The mandible and right parotid were not used because these structures significantly

Multiple estimation channel decoupling and optimization method based on inverse system

Science.gov (United States)

Wu, Peng; Mu, Rongjun; Zhang, Xin; Deng, Yanpeng

2018-03-01

This paper addressed the intelligent autonomous navigation request of intelligent deformation missile, based on the intelligent deformation missile dynamics and kinematics modeling, navigation subsystem solution method and error modeling, and then focuses on the corresponding data fusion and decision fusion technology, decouples the sensitive channel of the filter input through the inverse system of design dynamics to reduce the influence of sudden change of the measurement information on the filter input. Then carrying out a series of simulation experiments, which verified the feasibility of the inverse system decoupling algorithm effectiveness.

SDG multiple fault diagnosis by real-time inverse inference

International Nuclear Information System (INIS)

Zhang Zhaoqian; Wu Chongguang; Zhang Beike; Xia Tao; Li Anfeng

2005-01-01

In the past 20 years, one of the qualitative simulation technologies, signed directed graph (SDG) has been widely applied in the field of chemical fault diagnosis. However, the assumption of single fault origin was usually used by many former researchers. As a result, this will lead to the problem of combinatorial explosion and has limited SDG to the realistic application on the real process. This is mainly because that most of the former researchers used forward inference engine in the commercial expert system software to carry out the inverse diagnosis inference on the SDG model which violates the internal principle of diagnosis mechanism. In this paper, we present a new SDG multiple faults diagnosis method by real-time inverse inference. This is a method of multiple faults diagnosis from the genuine significance and the inference engine use inverse mechanism. At last, we give an example of 65t/h furnace diagnosis system to demonstrate its applicability and efficiency

SDG multiple fault diagnosis by real-time inverse inference

Energy Technology Data Exchange (ETDEWEB)

Zhang Zhaoqian; Wu Chongguang; Zhang Beike; Xia Tao; Li Anfeng

2005-02-01

In the past 20 years, one of the qualitative simulation technologies, signed directed graph (SDG) has been widely applied in the field of chemical fault diagnosis. However, the assumption of single fault origin was usually used by many former researchers. As a result, this will lead to the problem of combinatorial explosion and has limited SDG to the realistic application on the real process. This is mainly because that most of the former researchers used forward inference engine in the commercial expert system software to carry out the inverse diagnosis inference on the SDG model which violates the internal principle of diagnosis mechanism. In this paper, we present a new SDG multiple faults diagnosis method by real-time inverse inference. This is a method of multiple faults diagnosis from the genuine significance and the inference engine use inverse mechanism. At last, we give an example of 65t/h furnace diagnosis system to demonstrate its applicability and efficiency.

MULTI-LINE STOKES INVERSION FOR PROMINENCE MAGNETIC-FIELD DIAGNOSTICS

International Nuclear Information System (INIS)

Casini, R.; Lopez Ariste, A.; Paletou, F.; Leger, L.

2009-01-01

We present test results on the simultaneous inversion of the Stokes profiles of the He I lines at 587.6 nm (D 3 ) and 1083.0 nm in prominences (90 deg. scattering). We created data sets of synthetic Stokes profiles for the case of quiescent prominences (B -3 of the peak intensity for the polarimetric sensitivity of the simulated observations. In this work, we focus on the error analysis for the inference of the magnetic field vector, under the usual assumption that the prominence can be assimilated to a slab of finite optical thickness with uniform magnetic and thermodynamic properties. We find that the simultaneous inversion of the two lines significantly reduces the errors on the inference of the magnetic field vector, with respect to the case of single-line inversion. These results provide a solid justification for current and future instrumental efforts with multi-line capabilities for the observations of solar prominences and filaments.

INVERSION OF FULL ACOUSTIC WAVEFIELD IN LOCAL HELIOSEISMOLOGY: A STUDY WITH SYNTHETIC DATA

International Nuclear Information System (INIS)

Cobden, L. J.; Warner, M. R.; Tong, C. H.

2011-01-01

We present the first results from the inversion of full acoustic wavefield in the helioseismic context. In contrast to time-distance helioseismology, which involves analyzing the travel times of seismic waves propagating into the solar interior, wavefield tomography models both the travel times and amplitude variations present in the entire seismic record. Unlike the use of ray-based, Fresnel-zone, Born, or Rytov approximations in previous time-distance studies, this method does not require any simplifications to be made to the sensitivity kernel in the inversion. In this study, the acoustic wavefield is simulated for all iterations in the inversion. The sensitivity kernel is therefore updated while lateral variations in sound-speed structure in the model emerge during the course of the inversion. Our results demonstrate that the amplitude-based inversion approach is capable of resolving sound-speed structures defined by relatively sharp vertical and horizontal boundaries. This study therefore provides the foundation for a new type of subsurface imaging in local helioseismology that is based on the inversion of the entire seismic wavefield.

The attitude inversion method of geostationary satellites based on unscented particle filter

Science.gov (United States)

Du, Xiaoping; Wang, Yang; Hu, Heng; Gou, Ruixin; Liu, Hao

2018-04-01

The attitude information of geostationary satellites is difficult to be obtained since they are presented in non-resolved images on the ground observation equipment in space object surveillance. In this paper, an attitude inversion method for geostationary satellite based on Unscented Particle Filter (UPF) and ground photometric data is presented. The inversion algorithm based on UPF is proposed aiming at the strong non-linear feature in the photometric data inversion for satellite attitude, which combines the advantage of Unscented Kalman Filter (UKF) and Particle Filter (PF). This update method improves the particle selection based on the idea of UKF to redesign the importance density function. Moreover, it uses the RMS-UKF to partially correct the prediction covariance matrix, which improves the applicability of the attitude inversion method in view of UKF and the particle degradation and dilution of the attitude inversion method based on PF. This paper describes the main principles and steps of algorithm in detail, correctness, accuracy, stability and applicability of the method are verified by simulation experiment and scaling experiment in the end. The results show that the proposed method can effectively solve the problem of particle degradation and depletion in the attitude inversion method on account of PF, and the problem that UKF is not suitable for the strong non-linear attitude inversion. However, the inversion accuracy is obviously superior to UKF and PF, in addition, in the case of the inversion with large attitude error that can inverse the attitude with small particles and high precision.

Prediction, analysis and solution of flow inversion phenomenon in a typical MTR reactor with upward core cooling

International Nuclear Information System (INIS)

El-Morshedy, Salah El-Din

2010-01-01

Research reactors of power greater than 20 MW are usually designed to be cooled with upward coolant flow direction inside the reactor core. This is mainly to prevent flow inversion problems following a pump coast down. However, in some designs and under certain operating conditions, flow inversion phenomenon is predicted. In the present work, the best-estimate Material Testing Reactors Thermal-Hydraulic Analysis program (MTRTHA) is used to simulate a typical MTR reactor behavior with upward cooling under a hypothetical case of loss of off-site power. The flow inversion phenomenon is predicted under certain decay heat and/or pool temperature values below the design values. The reactor simulation under loss of off-site power is performed for two cases namely; two-flap valves open and one flap-valve fails to open. The model results for the flow inversion phenomenon prediction is analyzed and a solution of the problem is suggested. (orig.)

Model-based inversion for the characterization of crack-like defects detected by ultrasound in a cladded component; Etude d'une methode d'inversion basee sur la simulation pour la caracterisation de fissures detectees par ultrasons dans un composant revetu

Energy Technology Data Exchange (ETDEWEB)

Haiat, G

2004-03-01

This work deals with the inversion of ultrasonic data. The industrial context of the study in the non destructive evaluation of the internal walls of French reactor pressure vessels. Those inspections aim at detecting and characterizing cracks. Ultrasonic data correspond to echographic responses obtained with a transducer acting in pulse echo mode. Cracks are detected by crack tip diffraction effect. The analysis of measured data can become difficult because of the presence of a cladding, which surface is irregular. Moreover, its constituting material differs from the one of the reactor vessel. A model-based inverse method uses simulation of propagation and of diffraction of ultrasound taking into account the irregular properties of the cladding surface, as well as the heterogeneous nature of the component. The method developed was implemented and tested on a set of representative cases. Its performances were evaluated by the analysis of experimental results. The precision obtained in the laboratory on experimental cases treated is conform with industrial expectations motivating this study. (author)

Test plan for Fauske and Associates to perform tube propagation experiments with simulated Hanford tank wastes

International Nuclear Information System (INIS)

Carlson, C.D.; Babad, H.

1996-05-01

This test plan, prepared at Pacific Northwest National Laboratory for Westinghouse Hanford Company, provides guidance for performing tube propagation experiments on simulated Hanford tank wastes and on actual tank waste samples. Simulant compositions are defined and an experimental logic tree is provided for Fauske and Associates (FAI) to perform the experiments. From this guidance, methods and equipment for small-scale tube propagation experiments to be performed at the Hanford Site on actual tank samples will be developed. Propagation behavior of wastes will directly support the safety analysis (SARR) for the organic tanks. Tube propagation may be the definitive tool for determining the relative reactivity of the wastes contained in the Hanford tanks. FAI have performed tube propagation studies previously on simple two- and three-component surrogate mixtures. The simulant defined in this test plan more closely represents actual tank composition. Data will be used to support preparation of criteria for determining the relative safety of the organic bearing wastes

Development of highly-ordered, ferroelectric inverse opal films using sol gel infiltration

Science.gov (United States)

Matsuura, N.; Yang, S.; Sun, P.; Ruda, H. E.

2005-07-01

Highly-ordered, ferroelectric, Pb-doped Ba0.7Sr0.3TiO3, inverse opal films were fabricated by spin-coating a sol gel precursor into a polystyrene artificial opal template followed by heat treatment. Thin films of the ferroelectric were independently studied and were shown to exhibit good dielectric properties and high refractive indices. The excellent quality of the final inverse opal film using this spin-coating infiltration method was confirmed by scanning electron microscopy images and the good correspondence between optical reflection data and theoretical simulations. Using this method, the structural and material parameters of the final ferroelectric inverse opal film were easily adjusted by template heating and through repeated infiltrations, without changes in the initial template or precursor. Also, crack-free inverse opal thin films were fabricated over areas comparable to that of the initial crack-free polystyrene template (˜100 by 100 μm2).

Prostate Dose Escalation by Innovative Inverse Planning-Driven IMRT

National Research Council Canada - National Science Library

Xing, Lei

2005-01-01

.... Because of the tacit ignorance of intra-structural tradeoff, the IMRT plans generated by these systems for prostate treatment are, at best, sub-optimal and our endeavor of providing the best possible...

Estimation of biological parameters of marine organisms using linear and nonlinear acoustic scattering model-based inversion methods.

Science.gov (United States)

Chu, Dezhang; Lawson, Gareth L; Wiebe, Peter H

2016-05-01

The linear inversion commonly used in fisheries and zooplankton acoustics assumes a constant inversion kernel and ignores the uncertainties associated with the shape and behavior of the scattering targets, as well as other relevant animal parameters. Here, errors of the linear inversion due to uncertainty associated with the inversion kernel are quantified. A scattering model-based nonlinear inversion method is presented that takes into account the nonlinearity of the inverse problem and is able to estimate simultaneously animal abundance and the parameters associated with the scattering model inherent to the kernel. It uses sophisticated scattering models to estimate first, the abundance, and second, the relevant shape and behavioral parameters of the target organisms. Numerical simulations demonstrate that the abundance, size, and behavior (tilt angle) parameters of marine animals (fish or zooplankton) can be accurately inferred from the inversion by using multi-frequency acoustic data. The influence of the singularity and uncertainty in the inversion kernel on the inversion results can be mitigated by examining the singular values for linear inverse problems and employing a non-linear inversion involving a scattering model-based kernel.

Asian Rhinoplasty: Preoperative Simulation and Planning Using Adobe Photoshop.

Science.gov (United States)

Kiranantawat, Kidakorn; Nguyen, Anh H

2015-11-01

A rhinoplasty in Asians differs from a rhinoplasty performed in patients of other ethnicities. Surgeons should understand the concept of Asian beauty, the nasal anatomy of Asians, and common problems encountered while operating on the Asian nose. With this understanding, surgeons can set appropriate goals, choose proper operative procedures, and provide an outcome that satisfies patients. In this article the authors define the concept of an Asian rhinoplasty-a paradigm shift from the traditional on-top augmentation rhinoplasty to a structurally integrated augmentation rhinoplasty-and provide a step-by-step procedure for the use of Adobe Photoshop as a preoperative program to simulate the expected surgical outcome for patients and to develop a preoperative plan for surgeons.

Inversion of convergent-beam electron diffraction patterns

International Nuclear Information System (INIS)

Bird, D.M.; Saunders, M.

1992-01-01

The problem of recovering the structure factors that contribute to a zone-axis convergent-beam diffraction pattern is discussed. It is shown that an automated matching procedure that minimizes the sum-of-squares difference between experimental and simulated patterns is effective whether one is refining accurate structure factors in a known crystal or attempting ab initio structure determination. The details of the minimization method are analysed and it is shown that a quasi-Newton method that uses analytically derived gradients is particulary effective when several structure factors are varied. The inversion method for ab initio structure determination is tested on the [110] axis of GaP, using simulated patterns as ideal 'experimental' data. (orig.)

Inverse type II seesaw mechanism and its signature at the LHC and ILC

Energy Technology Data Exchange (ETDEWEB)

Freitas, F.F.; Pires, C.A. de S, E-mail: cpires@fisica.ufpb.br; Rodrigues da Silva, P.S.

2017-06-10

The advent of the LHC, and the proposal of building future colliders as the ILC, both programmed to explore new physics at the TeV scale, justify the recent interest in collider phenomenology of seesaw mechanisms whose signatures lie on TeV scale or less. The most popular TeV scale seesaw mechanisms are the inverse seesaw ones. There are three types of inverse seesaw mechanisms, but only that one implemented in an arrangement involving six non-standard heavy neutrinos has received attention. In this paper we develop an inverse seesaw mechanism based on Higgs triplet model and simulate its collider phenomenology by producing doubly charged Higgses at the LHC and ILC and analyzing their subsequent decays in pair of leptons. We find that although the new scalars decouple from the standard ones, signals of these scalars may be detected in the current run of the LHC or in the future ILC. Our simulations probe the model in the region of parameter space that generates the correct neutrino masses and mixing for both normal and inverted hierarchy cases.

Retrieving rupture history using waveform inversions in time sequence

Science.gov (United States)

Yi, L.; Xu, C.; Zhang, X.

2017-12-01

The rupture history of large earthquakes is generally regenerated using the waveform inversion through utilizing seismological waveform records. In the waveform inversion, based on the superposition principle, the rupture process is linearly parameterized. After discretizing the fault plane into sub-faults, the local source time function of each sub-fault is usually parameterized using the multi-time window method, e.g., mutual overlapped triangular functions. Then the forward waveform of each sub-fault is synthesized through convoluting the source time function with its Green function. According to the superposition principle, these forward waveforms generated from the fault plane are summarized in the recorded waveforms after aligning the arrival times. Then the slip history is retrieved using the waveform inversion method after the superposing of all forward waveforms for each correspond seismological waveform records. Apart from the isolation of these forward waveforms generated from each sub-fault, we also realize that these waveforms are gradually and sequentially superimposed in the recorded waveforms. Thus we proposed a idea that the rupture model is possibly detachable in sequent rupture times. According to the constrained waveform length method emphasized in our previous work, the length of inverted waveforms used in the waveform inversion is objectively constrained by the rupture velocity and rise time. And one essential prior condition is the predetermined fault plane that limits the duration of rupture time, which means the waveform inversion is restricted in a pre-set rupture duration time. Therefore, we proposed a strategy to inverse the rupture process sequentially using the progressively shift rupture times as the rupture front expanding in the fault plane. And we have designed a simulation inversion to test the feasibility of the method. Our test result shows the prospect of this idea that requiring furthermore investigation.

DEFINED CONTRIBUTION PLANS, DEFINED BENEFIT PLANS, AND THE ACCUMULATION OF RETIREMENT WEALTH

Science.gov (United States)

Poterba, James; Rauh, Joshua; Venti, Steven; Wise, David

2010-01-01

The private pension structure in the United States, once dominated by defined benefit (DB) plans, is currently divided between defined contribution (DC) and DB plans. Wealth accumulation in DC plans depends on the participant's contribution behavior and on financial market returns, while accumulation in DB plans is sensitive to a participant's labor market experience and to plan parameters. This paper simulates the distribution of retirement wealth under representative DB and DC plans. It uses data from the Health and Retirement Study (HRS) to explore how asset returns, earnings histories, and retirement plan characteristics contribute to the variation in retirement wealth outcomes. We simulate DC plan accumulation by randomly assigning individuals a share of wages that they and their employer contribute to the plan. We consider several possible asset allocation strategies, with asset returns drawn from the historical return distribution. Our DB plan simulations draw earnings histories from the HRS, and randomly assign each individual a pension plan drawn from a sample of large private and public defined benefit plans. The simulations yield distributions of both DC and DB wealth at retirement. Average retirement wealth accruals under current DC plans exceed average accruals under private sector DB plans, although DC plans are also more likely to generate very low retirement wealth outcomes. The comparison of current DC plans with more generous public sector DB plans is less definitive, because public sector DB plans are more generous on average than their private sector counterparts. PMID:21057597