scholarly journals Ship optimization using the preferences of the designer

Author(s):  
А.И. Гайкович

В статье рассматривается подход к решению задачи оптимизации характеристик корабля на ранних стадиях проектирования. Задача оптимизационного проектирования формулируется как многокритериальная. Дается краткий обзор подходов к решению задач математического программирования такого класса. Рассматривается такой метод многокритериальной оптимизации, широко используемый в экономических задачах, как оптимизация по Парето. Для решения задач, связанных с созданием технических систем, характерно большое количество частных критериев эффективности, выраженных, как правило, нелинейными функциями, а иногда описанными алгоритмическими процедурами. Следовательно, поверхность эффективных точек Парето, на которой ищется наилучший вариант проекта, представляет собой сложный геометрический объект в n- мерном пространстве частных критериев. Выбор наилучшего решения предлагается путем использования предпочтения проектанта, сформулированными в виде функции ценности. Функция ценности также является сложной поверхностью в n-мерном критериальном пространстве. Аналитическое решение, дающее координаты точек касания этих поверхностей, представляет сложную математическую проблему. В статье предлагается численный метод решения задачи оптимизации по Парето для сложной технической системы, каковой является корабль. The article considers an approach to solving the problem of optimizing the ship's characteristics at the early stages of design. The optimization design problem is formulated as a multi-criteria one. A brief overview of approaches to solving mathematical programming problems of this class is given. We consider such a method of multi-criteria optimization, widely used in economic problems, as Pareto optimization. To solve problems related to the creation of technical systems, a large number of specific performance criteria are characteristic, expressed, as a rule, by nonlinear functions, and sometimes described by algorithmic procedures. Consequently, the surface of effective Pareto points, on which the best variant of the project is sought, is a complex geometric object in the n-dimensional space of partial criteria. The choice of the best solution is proposed by using the preferences of the designer, formulated in the form of a value function. The value function is also a complex surface in the n-dimensional criterion space. The analytical solution that gives the coordinates of the points of contact of these surfaces is a complex mathematical problem. The paper proposes a numerical method for solving the Pareto optimization problem for a complex technical system, such as a ship.

2015 ◽  
Vol 61 (1) ◽  
pp. 181-193 ◽  
Author(s):  
Tzanko Donchev ◽  
Ammara Nosheen

Abstract Optimal control system described by differential inclusion with continuous and one sided Perron right-hand side in a finite dimensional space is studied in the paper. We prove that the value function is the unique solution of a proximal Hamilton-Jacobi inequalities.


2021 ◽  
pp. 168-178
Author(s):  
Hainan Yan ◽  
Yiting Zhang ◽  
Sheng Liu ◽  
Ka Ming Cheung ◽  
Guohua Ji

AbstractIn China's hot summer and cold winter areas, the façade design of buildings needs to respond to a variety of performance objectives. This study focuses on the optimization of daylight and solar radiation of building façade of office buildings in Nanjing and proposes a simple and efficient method. The method mainly includes a random sampling of design models, simplified operation of daylight performance criteria and selection of optimal solution. The results show that the building façade can improve the indoor lighting uniformity and reduce the indoor illumination level compared with the unshaded reference building. Besides, the amount of solar radiation received by office buildings in summer and winter becomes more balanced with the building façade. The optimization design method of building façade proposed in this study can be of guiding significance for office buildings in Nanjing.


Author(s):  
Norlenda Mohd Noor ◽  
Hanifah Sulaiman ◽  
Zuraida Alwadood ◽  
Suhaila Abd Halim ◽  
Nurul Filzah Syamimi Wahid ◽  
...  

<p>Mathematics is one of the basic and core subject for engineering students. Learning mathematics helps in developing problem solving skills as the subject requires critical thinking. However, many students perceive mathematics as a difficult subject and eventually get poor result for the subject. In the institution under study, there were increases in failure rate for the subject for the past few semesters. Based on a preliminary study, it was found that 55 percent of engineering student claimed that they encountered difficulties in visualizing functions in 3-dimensional space, which is the main content for engineering calculus subject. This fact is very unsatisfactory as engineering students are expected to possess strong mathematical problem solving skills. In light of this, the objective of this research is to develop an interactive teaching and learning tools, so as to assist students in visualizing 3-dimensional space functions. The tool is intended to be used in teaching and learning process in classrooms and it is expected that the students’ understanding in the subject could be improved.</p>


2005 ◽  
Vol 23 ◽  
pp. 1-40 ◽  
Author(s):  
N. Roy ◽  
G. Gordon ◽  
S. Thrun

Standard value function approaches to finding policies for Partially Observable Markov Decision Processes (POMDPs) are generally considered to be intractable for large models. The intractability of these algorithms is to a large extent a consequence of computing an exact, optimal policy over the entire belief space. However, in real-world POMDP problems, computing the optimal policy for the full belief space is often unnecessary for good control even for problems with complicated policy classes. The beliefs experienced by the controller often lie near a structured, low-dimensional subspace embedded in the high-dimensional belief space. Finding a good approximation to the optimal value function for only this subspace can be much easier than computing the full value function. We introduce a new method for solving large-scale POMDPs by reducing the dimensionality of the belief space. We use Exponential family Principal Components Analysis (Collins, Dasgupta & Schapire, 2002) to represent sparse, high-dimensional belief spaces using small sets of learned features of the belief state. We then plan only in terms of the low-dimensional belief features. By planning in this low-dimensional space, we can find policies for POMDP models that are orders of magnitude larger than models that can be handled by conventional techniques. We demonstrate the use of this algorithm on a synthetic problem and on mobile robot navigation tasks.


Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 254
Author(s):  
Chunfeng Zhang ◽  
Siguang An ◽  
Wei Wang ◽  
Dehui Lin

A moving meshing algorithm with mesh adaptive size function was proposed in this paper with regard to the modeling speed and solution accuracy of electromagnetic equipment in the optimization design process. In the proposed method, a mesh size function that considers curvature, feature size, and distance gradient restrictions is constructed, which can obtain high quality meshes and avoid excessive iteration; when the finite element mesh domain is deformed, only the mesh nodes close to the moving boundary are allowed to move, and the theory of force-balance is used combined with the second-order boundary projection algorithm to perform iterative optimization of the mesh node positions. The proposed method has the advantages of keeping the original mesh structure and minimum mesh deformation as well as speed up the convergence, save time in the finite element meshing, and ensure the quality of the generated mesh. Then, the proposed method was applied to a 37 kw motor for electromagnetic analysis, and the results obtained proved the accuracy of the algorithm; finally, the effectiveness of the mesh movement algorithm in three-dimensional space was tested by moving the sphere inside the cylinder.


1966 ◽  
Vol 25 ◽  
pp. 373
Author(s):  
Y. Kozai

The motion of an artificial satellite around the Moon is much more complicated than that around the Earth, since the shape of the Moon is a triaxial ellipsoid and the effect of the Earth on the motion is very important even for a very close satellite.The differential equations of motion of the satellite are written in canonical form of three degrees of freedom with time depending Hamiltonian. By eliminating short-periodic terms depending on the mean longitude of the satellite and by assuming that the Earth is moving on the lunar equator, however, the equations are reduced to those of two degrees of freedom with an energy integral.Since the mean motion of the Earth around the Moon is more rapid than the secular motion of the argument of pericentre of the satellite by a factor of one order, the terms depending on the longitude of the Earth can be eliminated, and the degree of freedom is reduced to one.Then the motion can be discussed by drawing equi-energy curves in two-dimensional space. According to these figures satellites with high inclination have large possibilities of falling down to the lunar surface even if the initial eccentricities are very small.The principal properties of the motion are not changed even if plausible values ofJ3andJ4of the Moon are included.This paper has been published in Publ. astr. Soc.Japan15, 301, 1963.


Author(s):  
R. A. Crowther

The reconstruction of a three-dimensional image of a specimen from a set of electron micrographs reduces, under certain assumptions about the imaging process in the microscope, to the mathematical problem of reconstructing a density distribution from a set of its plane projections.In the absence of noise we can formulate a purely geometrical criterion, which, for a general object, fixes the resolution attainable from a given finite number of views in terms of the size of the object. For simplicity we take the ideal case of projections collected by a series of m equally spaced tilts about a single axis.


Author(s):  
A. Tanaka ◽  
M. Yamaguchi ◽  
T. Hirano

The plasma polymerization replica method and its apparatus have been devised by Tanaka (1-3). We have published several reports on its application: surface replicas of biological and inorganic specimens, replicas of freeze-fractured tissues and metal-extraction replicas with immunocytochemical markers.The apparatus for plasma polymerization consists of a high voltage power supply, a vacuum chamber containing a hydrocarbon gas (naphthalene, methane, ethylene), and electrodes of an anode disk and a cathode of the specimen base. The surface replication by plasma polymerization in negative glow phase on the cathode was carried out by gassing at 0.05-0.1 Torr and glow discharging at 1.5-3 kV D.C. Ionized hydrocarbon molecules diffused into complex surface configurations and deposited as a three-dimensionally polymerized film of 1050 nm in thickness.The resulting film on the complex surface had uniform thickness and showed no granular texture. Since the film was chemically inert, resistant to heat and mecanically strong, it could be treated with almost any organic or inorganic solvents.


Author(s):  
David A. Agard ◽  
Yasushi Hiraoka ◽  
John W. Sedat

In an effort to understand the complex relationship between structure and biological function within the nucleus, we have embarked on a program to examine the three-dimensional structure and organization of Drosophila melanogaster embryonic chromosomes. Our overall goal is to determine how DNA and proteins are organized into complex and highly dynamic structures (chromosomes) and how these chromosomes are arranged in three dimensional space within the cell nucleus. Futher, we hope to be able to correlate structual data with such fundamental biological properties as stage in the mitotic cell cycle, developmental state and transcription at specific gene loci.Towards this end, we have been developing methodologies for the three-dimensional analysis of non-crystalline biological specimens using optical and electron microscopy. We feel that the combination of these two complementary techniques allows an unprecedented look at the structural organization of cellular components ranging in size from 100A to 100 microns.


Author(s):  
K. Urban ◽  
Z. Zhang ◽  
M. Wollgarten ◽  
D. Gratias

Recently dislocations have been observed by electron microscopy in the icosahedral quasicrystalline (IQ) phase of Al65Cu20Fe15. These dislocations exhibit diffraction contrast similar to that known for dislocations in conventional crystals. The contrast becomes extinct for certain diffraction vectors g. In the following the basis of electron diffraction contrast of dislocations in the IQ phase is described. Taking account of the six-dimensional nature of the Burgers vector a “strong” and a “weak” extinction condition are found.Dislocations in quasicrystals canot be described on the basis of simple shear or insertion of a lattice plane only. In order to achieve a complete characterization of these dislocations it is advantageous to make use of the one to one correspondence of the lattice geometry in our three-dimensional space (R3) and that in the six-dimensional reference space (R6) where full periodicity is recovered . Therefore the contrast extinction condition has to be written as gpbp + gobo = 0 (1). The diffraction vector g and the Burgers vector b decompose into two vectors gp, bp and go, bo in, respectively, the physical and the orthogonal three-dimensional sub-spaces of R6.


Sign in / Sign up

Export Citation Format

Share Document