Rapid Prototype Development Approach for Genetic Programming

Genetic Programming (GP) is an important approach to deal with complex problem analysis and modeling, and has been applied in a wide range of areas. The development of GP involves various aspects, including design of genetic operators, evolutionary controls and implementations of heuristic strategy, evaluations and other mechanisms. When designing genetic operators, it is necessary to consider the possible limitations of encoding methods of individuals. And when selecting evolutionary control strategies, it is also necessary to balance search efficiency and diversity based on representation characteristics as well as the problem itself. More importantly, all of these matters, among others, have to be implemented through tedious coding work. Therefore, GP development is both complex and time-consuming. To overcome some of these difficulties that hinder the enhancement of GP development efficiency, we explore the feasibility of mutual assistance among GP variants, and then propose a rapid GP prototyping development method based on πGrammatical Evolution (πGE). It is demonstrated through regression analysis experiments that not only is this method beneficial for the GP developers to get rid of some tedious implementations, but also enables them to concentrate on the essence of the referred problem, such as individual representation, decoding means and evaluation. Additionally, it provides new insights into the roles of individual delineations in phenotypes and semantic research of individuals.

Development of a welding system for 3D steel rapid prototyping process

Metal device rapid prototyping with welding is one of the research interests at present. A controlled inertial droplet transfer MAG welding (CIDTMAGW) process was developed for the 3D steel device rapid prototyping with metal deposition. In this process, by using a special designed wire feeder, a controlled inertia is imposed on the droplet formed on the wire tip and combines with the arc force to make it detached. Thus, according to the requirements of rapid prototyping, the arc heat and the droplet detaching force can be separately controlled to attain a stable and satisfactory metal deposition process. A CIDTMAGW system and a testing manipulator for the 3D steel device rapid prototyping are presented. The required software is completed as well. The experiments proved that the geometric formation of the rapid prototyping device with welding deposition is well agreed the data of the device CAD modeling. The surface of the deposited device is comparatively smooth.

Effects of processing parameters on figuration during the GMAW rapid prototyping process

As a deposition technology, gas metal arc welding （GMAW） has shown new promise for rapid prototyping of metallic parts. During the process of metal forming using the arc of GMA W, low heat input and stable droplet transition are critical to high quality figuration. The effects of various processing parameters on figuration quality were studied in the experiment of GMA W rapid prototyping using the wire of ERSO-6 , including welding voltage, wire feeding rate, welding speed and so on. The optimal parameters for ERSO-6 are obtained. Simultaneously, it is verified that the rapid prototyping parts with favorable structures and quality can be achieved under the conditions of low heat input and stable droplet transition.

On-line detection system of weld-based rapid prototyping process based on structured light

In order to realize the closed-loop control for rapid prototyping process based on gas metal arc welding, the geometric parameters of weld beads should be detected. In this study, a vision sensor system consisting of a linear laser projector and a CCD camera was designed to collect images of weld beads. Then, an image processing approach which combines with a Gaassian filter and an improved gravity method was used to extract the centerline of a light stripe based on VC ＋＋. Feature points of the centerline were identical directly by means of an image fusion algorithm. Experimental results show that image fusion is an effective approach to measure the width and height of the weld bead with high accuracy. This method can identify beads effectively in multi-pass welding and avoid designing different modes to suit all kinds of shapes.

Finite element analysis of temperature field during multi-layer multi-pass weld-based rapid prototyping

During weld-bused rapid prototyping, the component experiences complex thermal process. In this paper, the temperature field evolution, thermal cycle characteristics, and temperature gradients of multi-layer multi-puss weld-based rapid prototyping are investigated using three-dimensional finite element models presented. The single-puss weld-bused rapid prototyping experiment is carried out. Thermal cycles calculated agree with experimental measurements. Furthermore, simulated results indicate that there exist the pre-heating effect of the fore layer and the post-heating effect of the rear layer in the multi-layer multi-pass weld-based rapid prototyping. In the first layer, the heat accumulates obviously. After the first layer, the dimension increase of the high temperature region behind the molten pool is not obvious. The heat diffusion condition in the first layer is the best, the heat diffusion condition in the second layer is the worst, and the heat diffusion conditions in the higher layers improve gradually.

Modeling of welded bead profile for rapid prototyping by robotic MAG welding

As a deposition technology, robotic metal active gas （MAG） welding has shown new promise for rapid prototyping （ RP） of metallic parts. During the process of metal forming using robotic MAG welding, sectional profile of single-puss welded bead is critical to formed accuracy and quality of metal pans. In this paper, the experiments of single-pass welded bead for rapid prototyping using robotic MAG welding were carried out. The effect of some edge detectors on the cross-sectional edge of welded bead was discussed and curve fitting was applied using least square fitting. Consequently, the mathematical model of welded bead profile was developed. The experimental results show that good shape could be obtained under suitable welding parameters. Canny operator is suitable to edge detection of welded bead profile, and the mathematical model of welded bead profile developed is approximately parabola.

A Photo-Modeling Approach to Restituting 3D Model Data from Single 2D Imagery for Rapid Prototyping of Artifact Products

This article first generalizes the basic engineering phases of modern rapid prototyping processes, and then describes the techniques of data capture for data modeling and model making. The article also provides a brief overview of the photogrametric techniques of restitution of 3D objects, and highlights the difficulties and limitations of existing methods. It therefore presents a novel approach to photo-modeling for acquiring 3D model data from single 2D photorealistic images. Implementation of the approach is then described against a effectiveness of photo-modeling practice. background of rapid prototyping processes to demonstrate the

Study on Control of Pneumatic Selecting and Shifting Actuators Using Rapid Control Prototyping

A gearbox in-the-loop control platform using dSPACE real-time system is designed for the study on the control technology of pneumatic selecting and shifting actuators based on rapid control prototyping.The operational principle of such actuators was analyzed using dSPACE hardware and software,resulting in a better knowledge of the logical relationship among solenoid valves,gear positions of cylinders and system input/output.Based on these,a control model was developed under the Matlab/Simulink environment and rapidly improved to meet requirements through experiments.Relevant tests have shown that analysis efficiency on selecting and shifting actuators could be raised and development of control strategy facilitated.

PROTOTYPE SURFACE MICRO- PRECISION IN FUSED DEPOSITION MODELING PROCESS

To aim at prototype parts fabricated with fused deposition modeling （FDM） process, the problems how to improve and enhance their surface micro-precision are studied. The producing mechanism of surface roughness is explained with three aspects concretely including the principle error of rapid prototyping （RP） process, the inherent characteristics of FDM process, and some mi- cro-scratches on the surface of the extruded fiber. Based on the micro-characters of section shape of the FDM prototype, a physical model reflecting the outer shape characters is abstracted. With the physical simplified and deduced, the evaluating equations of surface roughness are acquired. According to the FDM sample parts with special design for experimental measurement, the real surface roughness values of different inclined planes are obtained. And the measuring values of surface roughness are compared with the calculation values. Furthermore, the causes of surface roughness deviation between measuring values and calculation values are respectively analyzed and studied. With the references of analytic conclusions, the measuring values of the experimental part surface are revised, and the revised values nearly accord with the calculation values. Based on the influencing principles of FDM process parameters and special post processing of FDM prototype parts, some concrete measures are proposed to reduce the surface roughness of FDM parts, and the applying effects are better.

3D Flash Display for STL Model in Rapid Prototyping System

A kind of 3D color graphics display system for the STL model is developed by calling the functions from Open GL graphic library through VC++6.0 under the Windows environment in this paper. The STL model is a high quality one that can be quiescent or animated. This system is conducive to find out the disfigurement of the STL model in a rapid prototyping process and to repair it. Therefore, the component quality can be enhanced.

Research on Nanofabrication Technology of Micro-/Nano-Stereo Rapid Prototyping of PCVD

At present, the most common micro/nano-scale fabri ca tion processes include the plane silicon process based on IC technology, stereo silicon process, LIGA, quasi-LIGA based on near ultra violet deep lithography, MEMS, energy beam etching and micro/nano-machining, etc. A common problem for t hese processes is the difficulty to fabricate arbitrary form for 3-dimensional micro/nano-parts, devices or mechanisms. To develop advanced MEMS manufacturin g technology, and to achieve fabrication of true 3-dimensional parts, devices or mechanisms, this paper proposes a nanofabrication technology for rapid proto typing of 3-dimensional parts, using plasma chemical vapor deposition (PCVD). This process can be describes as follows: A laser beam is produced by a low power, quasi molecule laser. It enters the vac uum chamber through a window, and is focused on with the substrate surface. A ga s in the chamber is ionized by the laser beam to produce PCVD on the substrate s urface, and forms a particle of the size of Ф100 nm (its thickness is about 100 nm). When the laser beam moves along X-axis, many particles form a line. Then the laser beam moves one step in Y-axis to form a new line. A plane is complete d by many lines. Then the substrate moves in Z-axis to form new plane. Eventu ally, many planes form a 3-dimensional component. Using available CAD/CAM softw are with this process, rapid prototyping of complex components can be achieved. A nanometer precision linear motor, such as that described in Chinese national p atent (patent No. ZL 98 2 16753.9), can be used to obtain the nanometer precisio n movements in the process. The process does not require mask, can be used for v arious rapid prototyping materials, to obtain high fabrication precision (its sc ale precision is 15 nm), and larger ratio of height to width of micro/nano-stru cture. It can find widespread applications in the fabrication of micro-mechani sm, trimming IC, and fabricating minilens, etc.

Conversion of Rapid Prototyping Models into Metallic Tools by Ceramic Moulding—an Indirect Rapid Tooling Process

A process to convert models made by rapid prototypi ng techniques like SL (stereolitography) and LOM (laminated object manufacturing) or by conventional techniques (silicones, resins, wax, etc.) into metallic mould s or tools has been developed. The main purpose of this technique is to rapidly obtain the first prototypes of parts, for plastics injection, forging or any oth er manufacturing process using the tools produced by casting a metal into a cera mic mould. Briefly, it can be said that the ceramic moulds are produced by mixing in variab le proportions, depending on the type of ceramics employed, strength and roughne ss desired, a ceramic mixture composed by alumina and/or zirconium silicates bon ded with silica coming from a liquid binder, based on ethyl silicate. A catalyst is added to the slurry in order to produce a sol-gel reaction. The liquid slur ry is poured into the box containing the mould to be reproduced. After a short p eriod of time, controlled by the amount of gelling agent, the ceramic mixture ac quires a rubber consistency. The pattern is removed from the ceramic mould, whic h is fired to stop the gelation reaction. After this stabilization the ceramic m ould is sintered at high temperatures in order to generate an inert mould wi th the desired strength in which almost all metallic alloys can be cast. The effect of ceramic materials (shape, granulometric distribution, chemical com position, etc.), processing parameters (proportion binder/ceramic/catalyst, sint ering conditions, etc.) and casting conditions (mould pre-heating temperature a nd pouring temperature) were studied in order to obtain metallic moulds or tools with tailored properties (high dimensional accuracy, low roughness and high mec hanical strength).

Development of a Wireless Environmental Data Acquisition Prototype Adopting Agile Practices: An Experience Report

The traditional software development model commonly named “waterfall” is unable to cope with the increasing functionality and complexity of modern embedded systems. In addition, it is unable to support the ability for businesses to quickly respond to new market opportunities due to changing requirements. As a response, the software development community developed the Agile Methodologies (e.g., extreme Programming, Scrum) which were also adopted by the Embedded System community. However, failures and bad experiences in applying Agile Methodologies to the development of embedded systems have not been reported in the literature. Therefore, this paper contributes a detailed account of our first-time experiences adopting an agile approach in the prototype development of a wireless environment data acquisition system in an academic environment. We successfully applied a subset of the extreme Programming (XP) methodology to our software development using the Python programming language, an experience that demonstrated its benefits in shaping the design of the software and also increasing productivity. We used an incremental development approach for the hardware components and adopted a “cumulative testing” approach. For the overall development process management, however, we concluded that the Promise/Commitment-Based Project Management (PB-PM/CBPM) was better suited. We discovered that software and hardware components of embedded systems are best developed in parallel or near-parallel. We learned that software components that pass automated tests may not survive in the tests against the hardware. Throughout this rapid prototyping effort, factors like team size and our availability as graduate students were major obstacles to fully apply the XP methodology.

Accuracy of Rapid Prototyping Biomodels Plotted by Three Dimensional Printing Technique:Ex Vivo Study

The rapid prototyping biomodels manufacturing is a recent technology with great importance in oral and maxillofacial surgery. It provides a better surgical planning, decrease of anesthesia time and great functional and esthetic results. The aim of this experimental study was to evaluate the accuracy of rapid prototyping biomodels built by three-dimensional printing (3DP) technique, since this is one of the least expensive methods available. Linear measurements of standardized bone defects and anatomic distances were compared using a digital caliper of high precision in nine dry mandibles (gold standard) and their respective biomodels. The Bland-Altman test was used for statistical analysis (5% level of significance). The results showed strong concordance between the dry mandibles and their respective biomodels, with discrepancies smaller than 2 mmin most cases (97.4%). We can conclude that the biomodels built by 3DP technique can be used for surgical planning in Dentistry.

Research on Containment Relationships between Rapid Prototyping Part and CAD Model

Aiming at the geometrical features of different containment relationships in Rapid Prototyping （RP）, a general method of achieving the RP layer＇s cusp distribution of the positive, negative and mixed tolerance is proposed to meet the part＇s different applications. The procedure is executed by projecting the current and the next section of the CAD model onto a horizontal plane, computing the union and the intersection of the sections to get the outer and the inner boundary, and then blending the boundaries using a rotary vector through a proper inner point in the intersection to achieve the current layer＇s scanning contour. The method can realize the layer＇s cusp distribution of the mixed tolerance with unequal cusp height, expanding the connotation of the mixed tolerance.

Influence of Tomographic Slice Thickness and Field of View Variation on the Reproduction of Thin Bone Structures for Rapid Prototyping Purposes-An in Vitro Study

This study assessed the influence of acquisition parameters of tomographic volumes on the reproduction of thin bone structures for rapid prototyping purposes. Two parameters were investigated: Field of View (FOV) and Slice Thickness (ST). The specimen was comprised of five pairs of 0.6 mm, 1.1 mm, 1.5 mm, 2.0 mm and 2.8 mm thick cortical bone plates. The plates were stuck into utility wax;the first plate of the pair was in vertical position while the second plate was oblique to the first one. Forty-five tomographic images were captured and separated into 3 groups of fifteen images. Each group had a specific FOV: 180 mm;250 mm and 430 mm, respectively. Within each of these three groups, tomographic slice thickness was varied for every five of the fifteen slices. Acquisitions were carried out with STs of 1 mm, 2.5 mm and 5 mm. The Cyclops Medical Station software was used in the voxel-to-voxel analysis of radiologic density, reaching a total of 1350 assessed images. ST and FOV variation influenced the reproduction of thin bone walls, and FOV was shown to be a very important parameter. The larger the acquisition FOV, the more reduction in the number of voxels within the range of reconstruction for cortical bone in all of the bone plates. The visual analysis of the images of very thin bone walls showed that there could be a sharp drop in the radiologic density value in several adjacent voxels, resulting in areas which might not be reproduced in the reconstruction.

Rapid Tooling-Rapid Abrading Process Integratedwith Rapid Prototyping

The paper is to outline a new process for manufacturing rapid graphite electrode. It detailsthe steps in Providing integration with Rapid Prototyping (RP) into rapid electrode abrading Process.The key to this combination is the successful model or patted creating using the RP technology.Significantly reduced lead-time, shortened learns curve, lowered revision changes cost and eliminatedor reduced mold polishing are the consequent results. high quality Electrical Discharge Machining(EDM) electrodes are sometimes difficult to be manufactured rapidly and are very time-consumingby conventional methods, even using Computer Numerical Control (CNC) machines. Abradingprovides a simple way to create etuemely detailed and complex electrode to make molds in toolingmaking industries. Integration with the rapid development of the Rapid Prototyping & Manufacturing(RP&M) technology, the rapid electrode abrading process has been regarded as one of the majorbreakthrough in tooling making technology.

Fabrication,structure and compression performance of Inconel 617 superalloy honeycomb

Inconel 617 metal honeycombs with designed porosity,cell size and cell morphology were fabricated using fused deposition modelling rapid prototype manufacturing.The microstructure and compression properties of Inconel 617 metal honeycomb were studied.The results indicate that Inconel 617 metal honeycomb structure can be fabricated using fused deposition modelling technique,the processes are simple and the size of honeycomb is controllable.The sintered Inconel 617 honeycombs consist of matrix,γ phase,and grain boundary precipitates,Cr7C3 and M23C6 type carbides.The honeycomb microstructure sintered using fine powder particles are denser than that of coarse powder particles.Yield strength and Young’s modulus increase with the relative density of honeycomb increasing.But the influence of the relative density on Young’s modulus is greater than that of yield strength.

Investigating on casting mold (or core) making with coated sand by the selected laser sintering

Using a special coated sand as the material of the selected laser sintering (SLS), the authors test and investigate the strength change of the test samples in terms of different sintering parameters (scanning speed, laser power, sintering thickness, and so on). The characteristics of coated sand hardening by laser beam are analyzed. The sintered mold (or core) for given casting is poured with molten metal.