On design of joint positions for minimum mass 3D frames

An iterative procedure for determining the joint positions and dimensions of cross-sections corresponding to a minimum mass space frame is presented. Stress constraints, displacement constraints and side constraints are taken into account, with the possibility for linking of the design variables, which in addition to the joint positions are the beam dimensions. The frame is assumed to carry consecutively a number of different systems of loads, including temperature loads and weights. The stressed state analysis includes tension, bending, shear and torsion of the beam elements. The optimization iteration includes a sequence of quadratic programming problems with the possibility of move-limits. Only “nearby” constraints (active strategy) are considered, and analytical expressions for the gradients are derived. Illustrative medium scale problems are presented.     

Optimal joint positions and stiffness distribution for minimum mass frames with damping constraints

Optimal design of frames including cross-sectional dimensions (size parameters) and rigid joint positions between beams (configuration parameters) is treated in the paper. The optimal design corresponds to a minimal mass structure with constraints set on damping capacity of free vibration modes. The sensitivity analysis of distinct as well as multiple frequencies is performed analytically using a complex variable sensitivity method. The linking process of size and configuration variables is applied to generate different classes of optimal designs. The numerical algorithm is based on quadratic approximation of the objective function and linear approximation of active constraints. The examples are provided for 2, 12, and 124 beam frames.Presented at WCSMO-2, Zakopane, Poland, May 26–30, 1997     

Optimal seismic design of 3D steel moment frames: different ductility types

Three different types of lateral resisting steel moment frames consisting of ordinary moment frame (OMF), intermediate moment frame (IMF) and special moment frame (SMF) are available for design of 3D frames in literature. In this paper, optimum seismic design of 3D steel moment frames with different types of lateral resisting systems are performed according to the AISC-LRFD design criteria. A comparison is made considering the results of the above mentioned frames of different ductility types. These frames are analyzed by Response Spectrum Analysis (RSA), and optimizations are performed using nine different well-established metaheuristic algorithms. Performances of these algorithms are then compared for introducing the most suitable metaheuristic algorithms for optimal design of the 3D frames.     

Harmony search algorithm for minimum cost design of steel frames with semi-rigid connections and column bases

Harmony search-based algorithm is developed to determine the minimum cost design of steel frames with semi-rigid connections and column bases under displacement, strength and size constraints. Harmony search (HS) is recently developed metaheuristic search algorithm which is based on the analogy between the performance process of natural music and searching for solutions of optimum design problems. The geometric non-linearity of the frame members, the semi-rigid behaviour of the beam-to-column connections and column bases are taken into account in the design algorithm. The results obtained by semi-rigid connection and column base modelling are also compared to one developed by rigid connection modelling. The efficiency of HS algorithm, in comparison with genetic algorithms (GAs), is verified with three benchmark examples. The results indicate that HS could obtain lighter frames and less cost values than those developed using GAs.     

Minimum mass design of elastic frames subjected to multiple load cases

For frames with stress- and displacement constraints subjected to multiple load cases the formulation is given that enables use of the unified optimization approach which combines finite element and linear programming. Sensitivity analysis is shown analytically for Timoshenko beam models with transformations for eccentricities. For a specific case of a portal frame for a crane a study is made of the influence of the given portal columns (boundary conditions), the relations to fully stressed designs, and the influence of slenderness, when displacement constraints are involved.     

Recognition of 3D planar objects in canonical frames

An algorithm for recognizing 3D planar objects by their boundaries is presented. Extreme points on a shape are extracted for constructing canonical frames, under which signatures are then generated for determining the similarity between shapes. The method is efficient and yields a high recognition rate.     

Optimum design of frames

In this paper optimum design of frames is discussed. Specifically, minimum weight design of steel frames in the elastic range of material behaviour is treated. The solution algorithm is designed and programmed for use on micro-computers to suit a design office environment. Stress and slenderness constraints are considered, however displacement constraints may readily be implemented. Three examples are given and the results are discussed.     

Topology optimization for minimum mass design considering local failure constraints and contact boundary conditions

This paper studies the optimum design of a 1×2 mechanical optical switch. First, a novel switch configuration is designed with an included antithermal mechanism. Then, parametric programs are developed to automatically generate the solid model and to analyze thermal behavior of the switch. From the analysis of the initial design, it revealed that the amount of transverse offset between fiber tips failed in satisfying the Bellcore specifications. Finally, an integrated program combining CAD software, genetic algorithms, and finite element software was developed for optimum design of optical switches. With the capability of continuously changing critical design parameters of the switch in the integrated design program, the final optimum design satisfying the design constraints and specifications can be found.     

Dynamic 3D modelling for architectural design

A graphics design system employing 2D input and display devices (such as the pen and tablet and the calligraphic CRT) to input, edit, and view 3D objects representing landscapes and architectural structures in realtime is discussed. Landscape is entered via a procedure that uses an inking algorithm to obtain 2D data defining the site's contours and additional available interactive devices to obtain the contour heights. Extrusion techniques and compound transformations are used to generate volumes from facial elements input via a suite of rubberband algorithms that take advantage of the graphics hardware. Dynamic menus, displayed transformation parameter values and extensive editing features facilitate user interaction. Architectural studies of complex structures built by combining basic architectural units input using extrusion techniques are presented.     

Graph grammars for evolutionary 3D design

A new interactive evolutionary 3D design system is presented. The representation is based on graph grammars, a fascinating and powerful formalism in which nodes and edges are iteratively rewritten by rules analogous to those of context-free grammars and shape grammars. The nodes of the resulting derived graph are labelled with Euclidean coordinates: therefore the graph fully represents a 3D beam design. Results from user-guided runs are presented, demonstrating the flexibility of the representation. Comparison with results using an alternative graph representation demonstrates that the graph grammar search space is more rich in organised designs. A set of numerical features are defined over designs. They are shown to be effective in distinguishing between the designs produced by the two representations, and between designs labelled by users as good or bad. The features allow the definition of a non-interactive fitness function in terms of proximity to target feature vectors. In non-interactive experiments with this fitness function, the graph grammar representation out-performs the alternative graph representation, and evolution out-performs random search.     

A mixed GA-PSO-based approach for performance-based design optimization of 2D reinforced concrete special moment-resisting frames

A mixed genetic algorithm and particle swarm optimization in conjunction with nonlinear static and dynamic analyses as a smart and simple approach is introduced for performance-based design optimization of two-dimensional (2D) reinforced concrete special moment-resisting frames. The objective function of the problem is considered to be total cost of required steel and concrete in design of the frame. Dimensions and longitudinal reinforcement of the structural elements are considered to be design variables and serviceability, special moment-resisting and performance conditions of the frame are constraints of the problem. First, lower feasible bond of the design variables are obtained via analyzing the frame under service gravity loads. Then, the joint shear constraint has been considered to modify the obtained minimum design variables from the previous step. Based on these constraints, the initial population of the genetic algorithm (GA) is generated and by using the nonlinear static analysis, values of each population are calculated. Then, the particle swarm optimization (PSO) technique is employed to improve keeping percent of the badly fitted populations. This procedure is repeated until the optimum result that satisfies all constraints is obtained. Then, the nonlinear static analysis is replaced with the nonlinear dynamic analysis and optimization problem is solved again between obtained lower and upper bounds, which is considered to be optimum result of optimization solution with nonlinear static analysis. It has been found that by mixing the analyses and considering the hybrid GA-PSO method, the optimum result can be achieved with less computational efforts and lower usage of materials.     

Analysis of 3D face forms for proper sizing and CAD of spectacle frames

Three-dimensional morphological variations in the human face were analysed using digital models of the human face, and the usefulness of such analysis in designing industrial products was demonstrated by validating spectacle frame designs based on an original sizing system developed based on the analysis. A normalized model of the three-dimensional face form was made for each of 56 young adult Japanese males. The morphological distances between subjects were defined, and subjects were divided into four groups based on analysis of the distance matrix. A prototype spectacle frame was designed for the average form of each of the four groups. Tightening force of the prototype frames was adjusted using the materialized average forms with soft material placed at the nasal bridge and side of the head. Four prototype frames as well as a conventional frame were evaluated using sensory evaluation and physical measurement of the pressure and slip in 38 young adult male subjects. For each of the 38 subjects, prototype frames were ranked according to the morphological similarity of the subjects and the average form of the four groups: the frame designed for the average form of the group most similar to the subject was #1, the frame designed for the average form of the next most similar group was #2, and so on. For the groups with smaller or narrower faces, new frame #1 was most preferred and had the best overall fit, smallest slip sensation and largest pressure sensation. The groups with larger or wider faces preferred tighter frames than new frame #1, because they were concerned that the frames might slip, although the frames did not. Most of the subjects habitually wore spectacles, and the reason that groups with larger or wider faces preferred tighter frames was thought to be that they were accustomed to tighter fitting frames.     

Analysis of 3D face forms for proper sizing and CAD of spectacle frames

Three-dimensional morphological variations in the human face were analysed using digital models of the human face, and the usefulness of such analysis in designing industrial products was demonstrated by validating spectacle frame designs based on an original sizing system developed based on the analysis. A normalized model of the three-dimensional face form was made for each of 56 young adult Japanese males. The morphological distances between subjects were defined, and subjects were divided into four groups based on analysis of the distance matrix. A prototype spectacle frame was designed for the average form of each of the four groups. Tightening force of the prototype frames was adjusted using the materialized average forms with soft material placed at the nasal bridge and side of the head. Four prototype frames as well as a conventional frame were evaluated using sensory evaluation and physical measurement of the pressure and slip in 38 young adult male subjects. For each of the 38 subjects, prototype frames were ranked according to the morphological similarity of the subjects and the average form of the four groups: the frame designed for the average form of the group most similar to the subject was #1, the frame designed for the average form of the next most similar group was #2, and so on. For the groups with smaller or narrower faces, new frame #1 was most preferred and had the best overall fit, smallest slip sensation and largest pressure sensation. The groups with larger or wider faces preferred tighter frames than new frame #1, because they were concerned that the frames might slip, although the frames did not. Most of the subjects habitually wore spectacles, and the reason that groups with larger or wider faces preferred tighter frames was thought to be that they were accustomed to tighter fitting frames.     

Estimation of displacements from two 3D frames obtained from stereo

A method for estimating 3D displacements from two stereo frames is presented. It is based on the hypothesize-and-verify paradigm used to match 3D line segments between the two frames. In order to reduce the complexity of the method, an assumption is made that objects are rigid. The formulate a set of complete rigidity constraints for 3D line segments and integrate the uncertainty of measurements in this formation. The hypothesize-and-verify stages of the method use an extended Kalman filter to produce estimates of the displacements and of their uncertainty. The algorithm is shown to work on indoor and natural scenes. It is also shown to be easily extended to the case in which several mobile objects are present. The method is quite robust, fast, and has been thoroughly tested on hundreds of real stereo frames     

3D model alignment based on minimum projection area

3D model alignment is an important step for applications such as 3D model retrieval and 3D model recognition. In this paper, we propose a novel Minimum Projection Area-based (MPA) alignment method for pose normalization. Our method finds three principal axes to align a model: the first principal axis gives the minimum projection area when we perform an orthographic projection of the model in the direction parallel to this axis, the second axis is perpendicular to the first axis and gives the minimum projection area, and the third axis is the cross product of the first two axes. We devise an optimization method based on Particle Swarm Optimization to efficiently find the axis with minimum projection area. For application in retrieval, we further perform axis ordering and orientation in order to align similar models in similar poses. We have tested MPA on several standard databases which include rigid/non-rigid and open/watertight models. Experimental results demonstrate that MPA has a good performance in finding alignment axes which are parallel to the ideal canonical coordinate frame of models and aligning similar models in similar poses under different conditions such as model variations, noise, and initial poses. In addition, it achieves a better 3D model retrieval performance than several commonly used approaches such as CPCA, NPCA, and PCA.     

Damage-reduction-based structural optimum design for seismic RC frames

The development of structural seismic design is briefly reviewed with an emphasis on different conceptual approaches and their success in practical engineering applications. The concept of damage-reduction-based seismic design is proposed, in which the whole structural system is either physically or functionally designed as two parts, the main-function part and the damage-reduction part. The main-function part satisfies the serviceability requirements of the structural system. The damage-reduction part is composed of several damage-reduction elements, which work under hazard loads to ensure the safety of the main-function part, and further maintain the serviceability of the structural system by specific damage-reduction techniques or even by failure of damage-reduction elements. The formulation of damage-reduction-based optimum design for seismic structures is presented and some related issues are addressed, including a simplified approach to reliability analysis, the evaluation of the structural loss expectation, and the modified enumeration method. Numerical examples of RC frames are examined. The results show that several measures of structural seismic performance, including the life-cycle cost, severe earthquake action, and the story-drift reliability index of the weakest story, can be improved by damage-reduction-based design compared with conventional design.     

Physical design for 3D system on package

The SoC paradigm is a system integration approach that integrates large numbers of transistors as well as various mixed-signal active and passive components onto a single chip. This realization-led to the 3D system-in-package (SiP) approach, alternatively called 3D ICs or 3D stacked die/package. Designers can take SiP a step further by embedding both active and passive components, but passive-component embedding is bulky and requires thick-film discrete components. Thick-film component embedding distinguishes SiP from system on package (SoP), an emerging 3D system integration concept that involves embedding both active and passive components. SoP, however, incorporates ultrathin films at microscale to embed the passive components, and the package rather than the board is the system. SoP overcomes both the computing and integration limitations of SoC, SiP, multichip modules (MCMs), and traditional system packaging by having global wiring as well as RF, digital, and optical component integration in the package instead of on the chip. Moreover, 3D SoP addresses the wire delay problem by enabling the replacement of long, slow global interconnects with short, fast vertical routes.     

Visualizing 3D configuration spaces for mechanical design

We describe configuration space visualization methods for mechanical design. The research challenge is to relate the configuration space geometry to the mechanical function of the parts. Our research addresses the fundamental design task of contact analysis. Contacts are the physical primitives that make mechanical systems out of collections of parts. Systems perform functions by transforming motions via part contacts. The shapes of the interacting parts impose constraints on their motions that largely determine the system function. Contact analysis involves deriving and analyzing these constraints. Designers use contact analysis to ensure correct function and to optimize performance. We illustrate contact analysis on the film advance of a movie camera     

A system for desktop conceptual 3D design

In the traditional design process for a 3D environment, people usually depict a rough prototype to verify their ideas, and iteratively modify its configuration until they are satisfied with the general layout. In this activity, one of the main operations is the rearrangement of single and composite parts of a scene. With current desktop virtual reality (VR) systems, the selection and manipulation of arbitrary objects in 3D is still difficult. In this work, we present new and efficient techniques that allow even novice users to perform meaningful rearrangement tasks with traditional input devices. The results of our work show that the presented techniques can be mastered quickly and enable users to perform complex tasks on composite objects. Moreover, the system is easy to learn, supports creativity, and is fun to use.