Fixed Control Points Research Articles

An improved radial basis function for marine vehicle hull form representation and optimization

The marine vehicle is one of the most important platforms in oceanic research and development. During the evolution of marine vehicle design, hull optimization is a key topic consisting of various steps such as hull deformation analysis, optimization algorithm selection and hydrodynamic performance evaluation. For hull deformation analysis, radial based function interpolation technique is usually applied with Wendland’s ψ3,1 function, which requires a great number of fixed points. To improve the optimization effect, this paper proposes a novel radial basis function for better support radius condition. According to the support radius condition, the effect of different deformation functions acting on hull form is studied. To verify the effectiveness of the improved radial basis function in marine vehicle hull optimization, a Series 60 hull is taken as the initial hull, and the Rankine source method is utilized as the solver to calculate the wave resistance coefficient. The Non-dominated Sorting Genetic Algorithm (NSGA) is applied to determine the optimal hull form at given speeds. By comparing the optimization results, the benefits and drawbacks of the improved radial basis function are analyzed. The results show that the number of fixed control points can be reduced by applying the improved radial basis function. When different deformation functions are acting on the marine vehicle hull, the improved radial basis function makes the gradient transition smoother. In the process of hull optimization, the wave resistance coefficient obtained by utilizing the improved function to deform the hull is smaller than that of using Wendland’s ψ3,1 function under different support radii.

Exploring and exploiting ant colony optimization algorithm for vertical highway alignment development

AbstractThe vertical alignment optimization is about developing a minimum cost curvilinear vertical profile of constrained grade sections and appropriate non‐overlapping vertical curves passing through fixed control points with elevation constraints. Variations in ground profile and discreteness in unit cutting and filling costs make it a non‐convex, noisy, constrained optimization problem with many local minima. Further, the gradient related constraints and vertical curvature are non‐linear. This paper presents an innovative exploring and exploiting ant colony optimization (E&E‐ACO) algorithm with an appropriate point sampling, vertical curve fitting strategies, and an intuitive feasible region identification approach for solving the vertical alignment optimization problem. The E&E‐ACO algorithm extensively explores the feasible search space to generate a set of potential solutions and effectively exploit the space around the potential solutions for developing the optimized vertical alignment. The efficacy of the proposed method is demonstrated using two case studies. In one case study, the optimized solution by the proposed method had a marginally better objective function value and about three times lesser computational time than the solution by the mesh adaptive direct search method. The optimized alignment satisfied the elevation constraints of fixed control points and imitated the manually designed real‐world vertical alignment. The linearly varying exploration and exploitation parameters had better convergence rate than the other tested variations. Further, the proposed method at the end of 1000 iterations yielded about six times better result than the traditional ACO algorithm.

Linear reduced order method for design-space dimensionality reduction and flow-field learning in hull form optimization

In the earlier stage of hull form optimization design, a series of design variables is usually needed to control the hull shape, so as to find optimal hull forms with better performance. In the surrogate-based hydrodynamic performance optimization for ships, with the increase of the dimensionality of design space, the number of new sample hulls to construct surrogate model needs to be larger, which will bring a large amount of calculation. Through reduced order method, the dimensionality of the optimization design space can be reduced while keeping the deformation range of the original design space to a great extent, for instance, using the linear combination of a smaller number of bases to represent the deformation range. In addition, in the later stage of hull form optimization design, flow field results of the new sample hulls can be fully utilized to do the dimensionality reduction multi-physics field learning. In this paper, the principle of the Proper Orthogonal Decomposition method is used and briefly introduced, the steps of dimensionality reduction of the design space are shown then, and some important problems for the design-space dimensionality reduction in the specific field of hull form optimization, such as retainability of fixed control points, irrelevance of the relative order of data to dimensionality reduction results, and decision of the new design space range after dimensionality reduction, are deep analyzed. Furthermore, taking the resistance optimization of the modified Wigley ship as an example, the specific application and error analysis of the dimensionality reduction method for design-space dimensionality reduction in the earlier stage of hull form optimization and the multi-physics field learning in the later stage of hull form optimization are given, and the applicability and reliability of the method are demonstrated by analyzing the influence of mode order and sample number on reconstruction effect of the hull shape or flow field, and the prediction effect of flow field for not-in-the-database new hull form in detail. Results show that the linear dimensionality reduction method can reduce samples needed for optimization, thus reduce the amount of calculation for the surrogate-based hull form optimization, and be used for quick prediction of multi-physics fields of any new form in the design space. Furthermore, it can not only be applied to the sensitivity analysis or a Pareto frontier selection in comprehensive performance optimization of hull form based on CFD, but also be implemented in the real-time forecast of the flow field and influence analysis of the ship performance when adjusting the hull form (or hull appendages).

Геодезическое обеспечение использования технологии лазерного сканирования для фиксации памятников культурного наследия

Preservation of cultural heritage is associated with their fixation by performing measurements. They are very effective when we use the terrestrial laser scanning method, as a means of obtaining the most complete and reliable information on the geometry of the object at a particular time. However, the method of laser scanning is not so widely represented in the technical literature, for instance, on Totalstation- or theodolite surveys due to the relatively recent introduction in geodetic practice, especially for the purposes of fixing monuments. There are many questions on application of this technology for the above mentioned aim, they focus on ensuring the required regulatory or its accuracy. The authors discuss a geodetic method for ensuring the precision of laser scanning surveys including the design and estimating the fixed control points’ exactness, as well as the tie ones. The influence of angular and linear measurements over the laser positioning accuracy is shown. The technique is demonstrated, including modeling design schemes and their comparison with actual data. The research results are confined to the world-class cultural heritage site of Baalbek temple complex in Lebanon.

Investigation the impact of maximum control point on dose calculation in Eclipse treatment planning system for lung SBRT

Purpose: Choosing an appropriate parameter on the computerized treatment planning systems (TPSs) influences on the accuracy of dose calculation. Several dosimetric parameters have been studied to achieve a more accurate dose and qualitative plan. The purpose of this study was to determine the impact of maximum control point on the dose calculation on Eclipse TPSs for lung Stereotactic Body Radiation Therapy (SBRT) considering the plan quality, the computation time and the treatment file size. Methods: Dose distributions for the 8 lung SBRT plans with varying maximum control point of 64, 166, and 320 were calculated by Eclipse TPSs with flattening filter free (FFF) beam. The treatment dose was prescribed at 85% isodose level of 54 Gy to the planning target volume (PTV). The dosimetric impact can be evaluated from target coverage, conformity index (CI), homogeneity index (HI), and organ at risk (OAR) doses, while the computation time and the file storage space were compared with the recommended number of control point. Results: The use of 64 control points per subfields tended to increase the dose at PTV and OARs comparing with the 166 and 320 control point plans, while the HI and CI values were similar. The average increases of OARs doses including the spinal cord, heart, esophagus and total lung depended on the photon beam energy. The higher average control point (AVG) number leaded to increase the computation time and the file size for both 6X-FFF and 10X-FFF photon beams. The correlations between AVG and plan storaage space were observed in the same ratio as the computation time. Conclusion: Using the minimal number of control point, the quantitative analysis in the PTV and OARs showed no clinically significant variation in dose, therefore choosing an optimal number of fixed control points leaded to balance the plan quality, the computation time and the file size.

RADIATION HYGIENIC MONITORING AND ASSESSMENT OF POPULATION DOSES IN RADIOACTIVELY CONTAMINATED AREAS OF TULA REGION

The goal. The analyses of radiation hygienic monitoring conducted in Tula region territories affected by the Chernobyl NPP accident regarding cesium-137 and strontium- 90 in the local foodstuffs and the analyses of populational annual effective dose. The materials and methods. The survey was conducted in Tula Region since 1997 to 2015. Over that period, more than fifty thousand samples of the main foodstuffs from the post-Chernobyl contaminated area were analyzed. Simultaneously with that, the external gamma - radiation dose rate was measured in the fixed control points. The dynamics of cesium -137 and strontium-90 content in foodstuffs were assessed along with the maximum values of the mean annual effective doses to the population and the contribution of the collective dose from medical exposures into the structure of the annual effective collective dose to the population. The results. The amount of cesium-137 and strontium -90 in the local foodstuffs was identified. The external gamma- radiation dose rate values were found to be stable and not exceeding the natural fluctuations range typical for the middle latitudes of Russia’s European territory. The maximum mean annual effective dose to the population reflects the stable radiation situation and does not exceed the permissible value of 1 mSv. The contribution of the collective dose from medical exposures of the population has been continuously reducing as well as the average individual dose to the population per one medical treatment under the annual increase of the medical treatments quantities. The conclusion. There is no exceedance of the admissible levels of cesium-137 and strontium- 90 content in the local foodstuffs. The mean annual effective dose to the population has decreased which makes it possible to transfer the settlements affected by the Chernobyl NPP accident to normal life style. This is covered by the draft concept of the settlements’ transfer to normal life style.

Simulation of realistic linac motion improves the accuracy of a Monte Carlo based VMAT plan QA system

PurposeTo investigate the use of a software-based pre-treatment QA system for VMAT, which incorporates realistic linac motion during delivery. MethodsA beam model was produced using the GATE platform for GEANT4 Monte Carlo dose calculations. Initially validated against static measurements, the model was then integrated with a VMAT delivery emulator, which reads plan files and generates a set of dynamic delivery instructions analogous to the linac control system. Monte Carlo simulations were compared to measurements on dosimetric phantoms for prostate and head and neck VMAT plans. Comparisons were made between calculations using fixed control points, and simulations of continuous motion utilising the emulator. For routine use, the model was incorporated into an automated pre-treatment QA system. ResultsThe model showed better agreement with measurements when incorporating linac motion: mean gamma pass (Γ<1) over 5 prostate plans was 100.0% at 3%/3mm and 97.4% at 2%/2mm when compared to measurement. For the head and neck plans, delivered to the anatomical phantom, gamma passes were 99.4% at 4%/4mm and 94.94% at 3%/3mm. For example simulations within patient CT data, gamma passes were observed which are within our centre’s tolerance for pre-treatment QA. ConclusionsThrough comparison to phantom measurements, it was found that the incorporation of a realistic linac motion improves the accuracy of the model compared to the simulation of fixed control points. The ability to accurately calculate dose as a second check of the planning system, and determine realistic delivery characteristics, may allow for the reduction of machine-based pre-treatment plan QA for VMAT.

Adaptive data fitting by the progressive-iterative approximation

In this paper, we develop the adaptive data fitting algorithms by virtue of the local property of the Progressive-iterative approximation (abbr. PIA), which generates the fitting curve (patch) by adjusting the control points of a blending curve (patch) iteratively. In the adaptive data fitting algorithms, the control points are classified into two classes, namely, active and fixed control points, and only the active control points need to be adjusted in each iteration, thus saving computation greatly. Lots of examples and experimental data are presented to demonstrate the efficiency of the adaptive data fitting algorithm. Since the PIA method can be made parallel easily, the adaptive data fitting algorithm developed in this paper has important applications in parallel large scale data fitting.

Analysis and Synthesis of Plasma Stabilization Systems in Tokamaks

The central problem to be investigated in this paper is plasma control in the toroidal magnetic chamber. It is well known that plasma as an object of control is a mobile non-stable dynamic system with extremely high values of physical parameters, temperature as high as millions centigrade, first of all. This fact rises very high the requirement for electromagnetic capture system control accuracy. The special attention is paid to the stabilization of the plasma to chamber walls gap in some fixed control points. Mathematical methods of stabilizing control design based on modem optimization theory are proposed.

Beach Erosion of Futtsu-Misaki Cuspate Spit Separating Tokyo Bay and Uraga Channel

Beach changes around Futtsu-misaki cuspate spit located at the mouth of Tokyo Bay and protruding west are investigated through the comparison of aerial photographs. It is found that shoreline has been eroded in recent years mainly due to lack of sand supply from the southern coast caused by the obstruction of continuous littoral transport by Shitazu fishery harbor. At the tip of the spit the seawall was destroyed and a concave shoreline was formed due to erosion as the shoreline became stable under the condition of two fixed control points at Dai-ichikaiho island and the tip of the seawall. Sand eroded from the tip of the spit was found to be carried to the north coast of the spit by wave action.

TREATMENT OF CHRONIC PAIN WITH ACUPUNCTURE

We performed 979 acupuncture treatments in 261 patients with chronic pain. A substantial number of patients stated that they had relief immediately following a series of four acupuncture treatments. It did not matter whether the needles were placed in the traditional meridian locations or in arbitrary fixed control points. Four weeks following treatment, 65% of the patients reported little or no reduction in the intensity of their pain, 17% reported a 50% reduction, and 18% at least a 75% reduction. ( JAMA 232:1133-1135, 1975)

Treatment of Chronic Pain With Acupuncture

We performed 979 acupuncture treatments in 261 patients with chronic pain. A substantial number of patients stated that they had relief immediately following a series of four acupuncture treatments. It did not matter whether the needles were placed in the traditional meridian locations of in arbitrary fixed control points. Four weeks following treatment, 65% of the patients reported little or no reduction in the intensity of their pain, 17% reported a 50% reduction, and 18% at least a 75% reduction.

The theory and application of external condition equations in trilateral adjustment

Abstract This article introduces a method of adjusting a trilateration net for the purpose of inducing an exact closure in azimuth, latitude, and longitude at fixed control points by the method of least squares.