Evalutionary algorithms for ship hull skinning approximation

Traditionally, the design process of a hull involves simulation using clay models. This must be done cautiously, accurately and efficiently in order to sustain the performance of ship. Presently, the current technology of Computer Aided Design, Manufacturing, Engineering and Computational Fluid Dynamic has enabled a 3D design and simulation of a hull be done at a lower cost and within a shorter period of time. Besides that, automated design tools allow the transformation of offset data in designing the hull be done automatically. One of the most common methods in constructing a hull from the offset data is the skinning method. Generally, the skinning method comprised of skinning interpolation and skinning approximation. Skinning interpolation constructs the surface perfectly but improper selection of parameterization methods may cause bumps, wiggles, or uneven surfaces on the generated surface. On the other hand, using the skinning surface approximation would mean that the surface can only be constructed closer to data points. Thus, the error between the generated surface and the data points must be minimized to increase the accuracy. Therefore, this study aims to solve the error minimization problem in order to produce a smoother and fairer surface by proposing Non Uniform Rational B-Spline surface using various evolutionary optimization algorithms, namely, Gravitational Search Algorithm, Particle Swarm Optimization and Genetic Algorithm. The proposed methods involve four procedures: extraction of offset data from line drawing plan; generation of control points; optimization of a surface; and validations of hull surfaces. Validation is done by analyzing the surface curvature and errors between the generated surface and the given data points. The experiments were implemented on both ship hull and free form models. The findings from the experiments are compared with interpolated skinning surface and conventional skinning surface approximation. The results show that the optimized skinning surfaces using the proposed methods yield a smaller error, less control points generation and feasible surfaces while maintaining the shape of the hull

Optimized NURBS Curve Based G-Code Part Program for CNC Systems

Indiana University-Purdue University Indianapolis (IUPUI)Computer Numerical Control (CNC) is widely used in many industries that needs high speed machining of the parts with high precision, accuracy and good surface finish. In order to avail this the generation of the CNC part program size will be immensely big and leads to an inefficient process, which increases the delivery time and cost of products. This work presents the automation of high-accuracy CNC tool trajectory planning from CAD to G-code generation through optimal NURBs surface approximation. The proposed optimization method finds the minimum number of NURBS control points for a given admissible theoretical cord error between the desired and manufactured surfaces. The result is a compact part program that is less sensitive to data starvation than circular and spline interpolations with potential better surface finish. The proposed approach is demonstrated with the tool path generation of an involute gear profile and a topologically optimized structure is developed using this approach and then finally it is 3D printed

Representation Of Rational Bézier Quadratics Using Genetic Algorithm, Differential Evolution And Particle Swarm Optimization

Data representation is a challenging problem in areas such as font reconstruction, medical image and scanned images. Direct mathematical techniques usually give smallest errors but sometime take a much longer time to compute. Alternatively, artificial intelligence techniques are widely used for optimization problem with shorter computation time. Besides, the usage of artificial technique for data representation is getting popular lately. Thus, this thesis is dedicated for the representation of curves and surfaces. Three soft computing techniques namely Genetic Algorithm (GA), Differential Evolution (DE) and Particle Swarm Optimization (PSO) are utilized for the desired manipulation of curves and surfaces. These techniques have been used to optimize control points and weights in the description of spline functions used. Preprocessing components such as corner detection and chord length parameterization are also explained in this thesis. For each proposed soft computing technique, parameter tuning is done as an essential study. The sum of squares error (SSE) is used as an objective function. Therefore, this is also a minimization problem where the best values for control points and weights are found when SSE value is minimized. Rational Bézier quadratics have been utilized for the representation of curves. Reconstruction of surfaces is achieved by extending the rational Bézier quadratics to their rational Bézier bi-quadratic counterpart. Our proposed curve and surface methods with additional help from soft computing techniques have been utilized to vectorize the 2D and 3D shapes and objects

PELATIHAN SOFTWARE RHINOCEROS DAN MAXSURF UNTUK MENINGKATKAN KOMPETENSI DESAIN 3D PENGRAJIN KAPAL TRADISIONAL DI PESISIR PEKALONGAN

ABSTRAKKota Pekalongan terletak di pantai utara Jawa Tengah dimana wilayah pesisir utara ini terdapat potensi yang dapat dikembangkan menjadi aset yang berharga bagi bangsa yaitu para pembuat kapal tradisional. Dalam pelaksanaannya, baik tipe ataupun bentuk kapal yang dibangun, berdasarkan pengalaman kapal-kapal yang pernah dibuat sebelumnya, tanpa melalui perhitungan dan penggambaran terlebih dahulu, sehingga dalam beberapa kasus terhadap pesanan kapal yang berbeda bentuknya, maka pengrajin ini akan mengalami kesulitan. Minimnya pengetahuan tentang gambar teknik juga menyebabkan para pengrajin kapal tradisional tidak dapat menggambar lambung kapal mereka. Hal ini menyebabkan perlunya sosialisasi mengenai teknologi perkapalan kepada pengrajin kapal di Kota Pekalongan terutama dibidang rancang bangun (design) dan konstruksi kapal agar terdapat standar baku mengenai konstruksi kapal kayu yang sesuai dengan standar yang ada seperti Biro Klasifikasi Indonesia (BKI). Pelatihan dilakukan dengan metode presentasi, demonstrasi, serta praktik langsung. Untuk mengukur pencapaian maka dilakukan pretest dan posttest yang dilakukan sebelum dan sesudah pelatihan. Hasil kuesioner menunjukkan adanya peningkatan pengetahuan peserta pelatihan desain kapal. Sebelum dilakukan pelatihan, rata-rata pengetahuan peserta sebesar 26% dalam memahami desain kapal dan 33% dalam memahami analisa tahanan kapal, kemudian mengalami peningkatan menjadi rata-rata sebesar 76% untuk pemahaman desain kapal dan 77% untuk analisa tahanan kapal setelah diberi pelatihan. Kata kunci: desain; pengrajin; kapal kayu; karakteristik kapal ABSTRACTThe city of Pekalongan is located on the north coast of Central Java where there is potential for this northern coastal region to be developed into a valuable asset for the nation, namely traditional shipbuilders. In practice, both the type and shape of the ship built, based on the experience of ships that have been made before, without going through calculations and drawings beforehand, so that in some cases orders for ships with different shapes, these craftsmen will experience difficulties. The lack of knowledge about technical drawings also causes traditional shipbuilders to be unable to draw their hulls. This causes the need for socialization regarding shipping technology to ship craftsmen in Pekalongan City, especially in the field of ship design and construction so that there are standard standards regarding wooden ship construction in accordance with existing standards such as the Indonesian Classification Bureau (BKI). The training is carried out using presentation methods, demonstrations, and hands-on practice. To measure achievement, a questionnaire was filled out before and after the training. The results of the questionnaire showed an increase in the knowledge of ship design training participants. Before the training, the average knowledge of the participants was 26% in understanding ship design and 33% in understanding ship resistance analysis, then increased to an average of 76% for understanding ship design and 77% for ship resistance analysis after being given training. Keywords: design; craftsmen; wooden ships; ship characteristic

FITTING A PARAMETRIC MODEL TO A CLOUD OF POINTS VIA OPTIMIZATION METHODS

Computer Aided Design (CAD) is a powerful tool for designing parametric geometry. However, many CAD models of current configurations are constructed in previous generations of CAD systems, which represent the configuration simply as a collection of surfaces instead of as a parametrized solid model. But since many modern analysis techniques take advantage of a parametrization, one often has to re-engineer the configuration into a parametric model. The objective here is to generate an efficient, robust, and accurate method for fitting parametric models to a cloud of points. The process uses a gradient-based optimization technique, which is applied to the whole cloud, without the need to segment or classify the points in the cloud a priori. First, for the points associated with any component, a variant of the Levenberg-Marquardt gradient-based optimization method (ILM) is used to find the set of model parameters that minimizes the least-square errors between the model and the points. The efficiency of the ILM algorithm is greatly improved through the use of analytic geometric sensitivities and sparse matrix techniques. Second, for cases in which one does not know a priori the correspondences between points in the cloud and the geometry model\u27s components, an efficient initialization and classification algorithm is introduced. While this technique works well once the configuration is close enough, it occasionally fails when the initial parametrized configuration is too far from the cloud of points. To circumvent this problem, the objective function is modified, which has yielded good results for all cases tested. This technique is applied to a series of increasingly complex configurations. The final configuration represents a full transport aircraft configuration, with a wing, fuselage, empennage, and engines. Although only applied to aerospace applications, the technique is general enough to be applicable in any domain for which basic parametrized models are available

Algorithms for Geometric Optimization and Enrichment in Industrialized Building Construction

The burgeoning use of industrialized building construction, coupled with advances in digital technologies, is unlocking new opportunities to improve the status quo of construction projects being over-budget, delayed and having undesirable quality. Yet there are still several objective barriers that need to be overcome in order to fully realize the full potential of these innovations. Analysis of literature and examples from industry reveal the following notable barriers: (1) geometric optimization methods need to be developed for the stricter dimensional requirements in industrialized construction, (2) methods are needed to preserve model semantics during the process of generating an updated as-built model, (3) semantic enrichment methods are required for the end-of-life stage of industrialized buildings, and (4) there is a need to develop pragmatic approaches for algorithms to ensure they achieve required computational efficiency. The common thread across these examples is the need for developing algorithms to optimize and enrich geometric models. To date, a comprehensive approach paired with pragmatic solutions remains elusive. This research fills this gap by presenting a new approach for algorithm development along with pragmatic implementations for the industrialized building construction sector. Computational algorithms are effective for driving the design, analysis, and optimization of geometric models. As such, this thesis develops new computational algorithms for design, fabrication and assembly, onsite construction, and end-of-life stages of industrialized buildings. A common theme throughout this work is the development and comparison of varied algorithmic approaches (i.e., exact vs. approximate solutions) to see which is optimal for a given process. This is implemented in the following ways. First, a probabilistic method is used to simulate the accumulation of dimensional tolerances in order to optimize geometric models during design. Second, a series of exact and approximate algorithms are used to optimize the topology of 2D panelized assemblies to minimize material use during fabrication and assembly. Third, a new approach to automatically update geometric models is developed whereby initial model semantics are preserved during the process of generating an as-built model. Finally, a series of algorithms are developed to semantically enrich geometric models to enable industrialized buildings to be disassembled and reused. The developments made in this research form a rational and pragmatic approach to addressing the existing challenges faced in industrialized building construction. Such developments are shown not only to be effective in improving the status quo in the industry (i.e., improving cost, reducing project duration, and improving quality), but also for facilitating continuous innovation in construction. By way of assessing the potential impact of this work, the proposed algorithms can reduce rework risk during fabrication and assembly (65% rework reduction in the case study for the new tolerance simulation algorithm), reduce waste during manufacturing (11% waste reduction in the case study for the new panel unfolding and nesting algorithms), improve accuracy and automation of as-built model generation (model error reduction from 50.4 mm to 5.7 mm in the case study for the new parametric BIM updating algorithms), reduce lifecycle cost for adapting industrialized buildings (15% reduction in capital costs in the computational building configurator) and reducing lifecycle impacts for reusing structural systems from industrialized buildings (between 54% to 95% reduction in average lifecycle impacts for the approach illustrated in Appendix B). From a computational standpoint, the novelty of the algorithms developed in this research can be described as follows. Complex geometric processes can be codified solely on the innate properties of geometry – that is, by parameterizing geometry and using methods such as combinatorial optimization, topology can be optimized and semantics can be automatically enriched for building assemblies. Employing the use of functional discretization (whereby continuous variable domains are converted into discrete variable domains) is shown to be highly effective for complex geometric optimization approaches. Finally, the algorithms encapsulate and balance the benefits posed by both parametric and non-parametric schemas, resulting in the ability to achieve both high representational accuracy and semantically rich information (which has previously not been achieved or demonstrated). In summary, this thesis makes several key improvements to industrialized building construction. One of the key findings is that rather than pre-emptively determining the best suited algorithm for a given process or problem, it is often more pragmatic to derive both an exact and approximate solution and then decide which is optimal to use for a given process. Generally, most tasks related to optimizing or enriching geometric models is best solved using approximate methods. To this end, this research presents a series of key techniques that can be followed to improve the temporal performance of algorithms. The new approach for developing computational algorithms and the pragmatic demonstrations for geometric optimization and enrichment are expected to bring the industry forward and solve many of the current barriers it faces

Development of an Optimization Framework for the Design of High Speed Planing Craft

High speed planing craft play key roles in supporting several critical maritime activities, e.g., coastal surveillance, reconnaissance, life-saving operations, passenger and high value cargo transport. Despite their significant use, formal optimization frameworks have rarely been proposed to deal with their design challenges. In this thesis, an optimization framework for the preliminary design of high speed planing craft is presented. Several case studies of single- and multi-objective formulations of high speed planing craft design problem are solved using state-of-the-art optimization algorithms. The notion of scenario-based design optimization and innovization, i.e. a means to uncover design relations are also discussed. A modular, extensible design optimization framework that allows the analysis tools to be extended or replaced with the desired level of complexity or with the state-of-the-art analysis tools is proposed in this thesis. A validated 3D mathematical model of high speed planing craft hull form has been identified in this thesis. The use of global parametric transformation that preserves surface fairness and allows for the presence of curve discontinuities is incorporated. A suite of three state-of-the-art optimization algorithms, namely NSGA-II, IDEA and SA-EA is incorporated within the framework. The performances of the algorithms are compared using the case studies. Solutions to single-objective minimization of calm water resistance, resistance in a seaway and multi-objective formulations considering minimization of total resistance, vertical impact acceleration and steady turning diameter have been presented. The capability of the framework to capture design trade-offs is illustrated. The case studies are extended to provide for scenario-based design optimization in order to demonstrate the capability of the framework to solve optimization problems based on the ship's operational profile and operating conditions. A concept of innovization, which allows for the automatic discovery of design rules governing optimum hull forms, is introduced. The relationship gathered through the process of innovization is applied as a cheap pseudo-performance indicator within an optimization formulation, where the results compare favourably with the empirical estimate obtained from experimental data. Such extensions are new contributions to the ship design discipline, in which opens up the possibility of the development of optimum design rules for any particular ship class

Advances on Mechanics, Design Engineering and Manufacturing III

This open access book gathers contributions presented at the International Joint Conference on Mechanics, Design Engineering and Advanced Manufacturing (JCM 2020), held as a web conference on June 2–4, 2020. It reports on cutting-edge topics in product design and manufacturing, such as industrial methods for integrated product and process design; innovative design; and computer-aided design. Further topics covered include virtual simulation and reverse engineering; additive manufacturing; product manufacturing; engineering methods in medicine and education; representation techniques; and nautical, aeronautics and aerospace design and modeling. The book is organized into four main parts, reflecting the focus and primary themes of the conference. The contributions presented here not only provide researchers, engineers and experts in a range of industrial engineering subfields with extensive information to support their daily work; they are also intended to stimulate new research directions, advanced applications of the methods discussed and future interdisciplinary collaborations

Advances on Mechanics, Design Engineering and Manufacturing III

This open access book gathers contributions presented at the International Joint Conference on Mechanics, Design Engineering and Advanced Manufacturing (JCM 2020), held as a web conference on June 2–4, 2020. It reports on cutting-edge topics in product design and manufacturing, such as industrial methods for integrated product and process design; innovative design; and computer-aided design. Further topics covered include virtual simulation and reverse engineering; additive manufacturing; product manufacturing; engineering methods in medicine and education; representation techniques; and nautical, aeronautics and aerospace design and modeling. The book is organized into four main parts, reflecting the focus and primary themes of the conference. The contributions presented here not only provide researchers, engineers and experts in a range of industrial engineering subfields with extensive information to support their daily work; they are also intended to stimulate new research directions, advanced applications of the methods discussed and future interdisciplinary collaborations

Assessing the suitability of ship design for human factors issues associated with evacuation and normal operations

Evaluating ship layout for human factors (HF) issues using simulation software such as maritimeEXODUS can be a long and complex process. The analysis requires the identification of relevant evaluation scenarios; encompassing evacuation and normal operations; the development of appropriate measures which can be used to gauge the performance of crew and vessel and finally; the interpretation of considerable simulation data. In this paper we present a systematic and transparent methodology for assessing the HF performance of ship design which is both discriminating and diagnostic. The methodology is demonstrated using two variants of a hypothetical naval ship