Rapid prototyping, Current-voltage characteristics, and Feedback (Psychology)

Using a photovoltaic (PV) emulator (PVE) simplifies the testing of the PV generation system. However, conventional controllers used for PVEs suffer from oscillating output voltage, requiring a high number of iterations, or being too complex to be implemented. This paper proposes a controller based on a resistance feedback control strategy that produces a stable and fast converging operating point for the PVE. The resistance feedback control strategy requires a new type of PV model, which is the current–resistance (I–R) PV model. This model is computed using a binary search method at a fast convergence rate. It is combined with a closed-loop buck converter using a proportional-integral controller to form the resistance feedback control strategy. The PVE's controller is implemented into dSPACE ds1104 hardware platform for experimental validation. The acquired experimental results show that the proposed PVE is able to follow the current–voltage characteristic of the PV module accurately. In addition, the PVE's efficiency is more than 90% under maximum power point operation. The transient response of the proposed PVE is similar to the PV panel during irradiance changes. [ABSTRACT FROM AUTHOR]

Systems engineering, Rapid prototyping, Defense industries, Manufacturing processes, and Likelihood ratio tests

In 2007, John Young, then-Under Secretary of Defense for Acquisition, Technology and Logistics, mandated the use of "competitive prototyping" strategies in defense acquisition. Further, Department of Defense Instruction 5000.02 includes considerations for prototyping in the acquisition strategy. A 2017 memorandum circulated by Young lists five prototyping benefits, which are expected to "reduce technical risk, validate designs, validate cost estimates, evaluate manufacturing processes, and refine requirements." However, a process to assess whether, and to what extent, a prototype will be or has been successful in achieving these benefits is not currently in use by the Department of Defense. Because cost increases and schedule extension downsides are inherent in prototyping, such an assessment is critical. This research proposes an approach for assessing the likelihood of achieving expected prototyping benefits based on identifying the factors yielding these benefits as well as their relative weights. [ABSTRACT FROM AUTHOR]

Information resources management, Rapid prototyping, Industrial surveys, Computer software developers, Systems design, Organization, Contingency theory (Management), Management science, Systems development, Empirical research, Prototypes, and Computer systems

Many proposed contingencies regarding the conditions when the use of prototyping will lead to successful system development appear in the literature. Using an industry survey, this exploratory study empirically investigates the effect of certain contingencies on system success. Overall, results indicate that five variables, when combined with prototyping, affect system success (as indicated by user satisfaction): innovativeness of the project, impact of the system on the organization, user participation, number of users, and developer experience with prototyping. These results provide some insight into the proper uses of prototyping to improve system success. The results also indicate that several of the current contingencies, if followed, do not ensure high levels of system success. [ABSTRACT FROM AUTHOR]

Target costing, Prototypes, Product design, Rapid prototyping, and Suppliers

Prototyping allows firms to evaluate the technical feasibility of alternative product designs and to better estimate their costs. We study a collaborative prototyping scenario in which a manufacturer involves a supplier in the prototyping process by letting the supplier make detailed design choices for critical components and provide prototypes for testing. While the supplier can obtain private information about the costs, the manufacturer uses target costing to gain control over the design choice. We show that involving the supplier in the prototyping process has an important influence on the manufacturer's optimal decisions. The collaboration results in information asymmetry, which makes parallel prototyping less attractive and potentially reverses the optimal testing sequence under sequential prototyping: It may be optimal to test designs in increasing order of attractiveness to avoid that the supplier does not release technically and economically feasible prototypes for strategic reasons. We also find that the classical target costing approaches (cost‐ and market‐based) need to be adjusted in the presence of alternative designs: Due to the strategic behavior of suppliers, it is not always optimal to provide identical target costs for designs with similar cost and performance estimates, nor to provide different target costs for dissimilar designs. Furthermore, the timing is important: While committing upfront to carefully chosen target costs reduces the supplier's strategic behavior, in some circumstances, the manufacturer can take advantage of this behavior by remaining flexible and specifying the second prototype's target costs later. [ABSTRACT FROM AUTHOR]

Rapid prototyping, Search algorithms, Dielectric-loaded antennas, Three-dimensional printing, and Permittivity

A prototyping method for dielectrically loaded antennas is presented. Dielectric loading has been used with horn antennas, feeds, and lenses. Dielectrics have also been used for coating antennas submerged in water and biological matter and have led to improvements in bandwidth and efficiency as well as antenna miniaturisation. The authors present a new technique to produce variable dielectrics with permittivity from 6 to 28 using two commonly available powders, titanium dioxide (used in foods) and magnesium silicate (used in talcum powder). An example spherical helical ball antenna is used to demonstrate the process. In this antenna, the mixed powders were encased in a 3D printed shell that achieved a reduction in diameter of the spherical antenna by a factor of 1.85. The technique aids rapid prototyping and optimisation using search algorithms. [ABSTRACT FROM AUTHOR]

Rapid prototyping, Artificial neural networks, Induction machinery, Induction motors, Neural networks (Neurobiology), and Kalman filtering

This paper presents a discrete-time neural inverse optimal control for induction motors, which is implemented on a rapid control prototyping (RCP) system using a C2000 Microcontroller-Simulink platform. Such controller addresses the solution of three issues: system identification, trajectory tracking, and state estimation, which are solved independently. The neural controller is based on a recurrent high order neural network (RHONN), which is trained with an extended Kalman filter. The RHONN is an identifier to obtain an accurate motor model, which is robust to external disturbances and parameter variations. The inverse optimal controller is used to force the system to track a desired trajectory and to reject undesired disturbances. Moreover, the controller is based on a neural model and does not need the a-priori knowledge of motor parameters. A supertwisting observer is implemented to estimate the rotor magnetic fluxes. The hub of the RCP system is a TMS320f28069M MCU, which is an embedded combination of a 32-bit C28x DSP core and a real-time control accelerator. This Microcontroller is fully programmable from the Simulink environment. Simulation and experimental results illustrate the performance of the proposed controller and the RCP system, and a comparison with a control algorithm without the neural identifier is also included. [ABSTRACT FROM AUTHOR]

Relationship marketing, Marketing research, Customer relations, Customer loyalty, Database marketing, and Commercial products

As relationship marketing research evolved, a number of key constructs emerged. Some scholars have argued that these constructs are not conceptually or empirically distinct. We investigate this phenomenon based on the premise that sustained research effort towards studying conceptually overlapping/redundant constructs, while treating them as independent, can hamper the development of the field. We use prototyping, a method adopted from psychology, to examine consumers’ views of these constructs, and then identify relationship contexts where constructs are distinct or redundant. [ABSTRACT FROM AUTHOR]

Rapid prototyping, Management information systems, Decision support systems, Prototypes, and Production engineering

A new method is proposed for selecting the most appropriate rapid prototyping process according to user's specific requirements by using the expert system and fuzzy synthetic evaluation. The selection process is divided into two stages. First, it is necessary to generate feasible alternatives, which are executed under the expert system environment. Second, given those feasible alternatives, the fuzzy synthetic evaluation approach is employed to produce a ranking order of the alternatives and to finalize the most suirapid prototyping system. One distinctive characteristic of this method is that quantitative as well as qualitative measures are employed, providing more accurate results. The decision system developed based on the proposed method is composed of four modules: a database to store the specifications of various rapid prototyping processes; a knowledge-based expert system for determining the feasible alternatives; a fuzzy synthetic evaluation model to select the most suitable rapid prototyping process; and a user interface and an expert interface to interact with the system. The fuzzy synthetic evaluation approach used in the system is illustrated in detail by a numerical example. Furthermore, a Java-enabled solution, together with web techniques, is employed for developing such a networked decision support system. Finally, two examples of rapid prototyping process selection are designed to demonstrate the application of the system. The system has been implemented and can run at a rapid prototyping and manufacturing networked service platform that the authors have developed. [ABSTRACT FROM AUTHOR]

Application software, Rapid prototyping, Computer software, Computer-aided design, Manufacturing processes, and Interpolation

A direct-slicing approach might improve the accuracy and quality of small, complex parts produced with rapid prototyping technology. An application software based on direct slicing for rapid prototyping was used on the foundation of PowerSHAPE models. Lines, conic arcs and cubic bezier curves were adopted as the basic elements describing the direct-slicing contours. Moreover, a scheme to carry out subdivided software development was proposed. A picture (PIC) format file was selected as an interface for the slicing data, and a macro-AutoSection software, which collects the direct-slicing contour data of arbitrary complex computer-aided design models and provides power to produce the direct-slicing PIC files, was developed. On the above basis, an application software called PDSlice based on direct-slicing data processing was developed for the commercial selective laser sintering machine HRPS-III, which was made at the Huazhong University of Science and Technology (HUST), P. R. China. The major input and output interfaces as well as the PIC model reconstruction method of the PDSlice are described. Furthermore, a batch of direct-slicing polymer parts were successfully fabricated with the selective laser sintering machine. The application example shows that the accuracy and surface finish of three-dimensional complex curvature surface parts fabricated with the application software system based on a direct-slicing format were better than the application software system based on a stereolithography (STL) format. [ABSTRACT FROM AUTHOR]

Prototypes, Rapid prototyping, Computer integrated manufacturing systems, Industrial engineering, Mathematical models, Production planning, Computer-aided process planning, New product development, Concurrent engineering, Programming languages, C (Computer program language), Job analysis, and Manufacturing process automation

This paper presents a generative process planning system for parts produced by the rapid prototyping process (i.e. fused deposition modelling-FDM). The proposed process planning involves optimal selection of orientating the model with a proper support structure and then provides an intelligent slicing methodology, such as direct or adaptive, to minimise the built up time, keeping the geometry and cusp height errors in control. Pre- and post-slicing processes have been used to minimise the sliced data error. The Computer Aided Process Planning (CAPP) model has been arranged into five modules: orientation, support structure generation, slicing, path planning and Numerical Control (NC) program generation, and model build up. The CAPP model has been implemented in C language having a unique methodology consisting of 42 simplified steps. The CAPP model has been tested for several examples and shows satisfactory results. [ABSTRACT FROM AUTHOR]

Rapid prototyping, Computer-aided design, Prototypes, Finite element method, CAD/CAM systems, and Lithography

Rapid prototyping (RP) is an emerging, non-traditional fabrication method and has been recognized as a valid tool to shorten the lead-time from design to manufacture effectively. Most of the current RP systems adopt the triangular meshes of stereolithoraphy (STL) as a standard format for data input. Thus, the construction of triangular meshes directly affects the quality of RP parts and their subsequent processes. Traditionally, STL data are output from 3D CAD models built using commercial 3D CAD/CAM software packages. This study, however, differs from the traditional way in that it generates the STL data directly from scanned 3D data points, thus preventing various problems associated with 3D CAD modelling from a large quantity of data points. Specific tasks involved in this study include: (1) development of the methodology to convert massive data points into numerous, connected triangular meshes, (2) determination of unit normal vector for each triangular mesh facet, (3) output of triangular meshes with normal vectors in STL format, and (4) slicing of triangular-mesh model into a series of 2D sections. [ABSTRACT FROM AUTHOR]

Prototypes, Rapid prototyping, Industrial efficiency, Manufacturing processes, Industrial productivity, Industrial management, and Layer structure (Solids)

The geometric description used to represent solid objects significantly affects the accuracy and quality of the final parts produced with rapid prototyping (RP) technology. This paper discusses the alternative method of adaptive direct slicing for RP. Direct slicing generates precise contours for each layer from the solid model and avoids an intermediate representation. Adaptive slicing modifies the layer thickness to take into account the curvature of the surface of the solid model in the vertical direction, to alleviate the staircase effect, and to decrease the number of layers. Thereby, adaptive direct slicing potentially enables part fabrication with higher accuracy and production efficiency. This paper presents a new, practical approach to adaptive direct slicing based on the area deviation ratio. The slicing strategy and algorithm are also described. The corresponding procedure was implemented and tested on Windows 95/98 and NT 4.0 with AutoCAD R14. [ABSTRACT FROM AUTHOR]

Rapid prototyping, Paraffin wax, Centrifugal casting, Tensile strength, and Grain size

Centrifugal casting is a technology used for manufacturing hybrid rocket paraffin grains. This technology helps avoiding voids formation inside the solid paraffin as it cools. Voids are formed because of air bubbles being entrapped while pouring and because the liquid wax shrinks by 17–19% upon cooling. In this work, the centrifugal casting process for the manufacturing of paraffin cylinders was prototyped at two different scales considering critical casting issues. The effects of process parameters (rotational speed, melt temperature, and flow rate) on the tensile properties of the manufactured grains were analyzed. The results of the optimization conducted at the lower scale (2.5 kg) were up scaled to manufacture 25 kg grains. The resulting mechanical properties complied with the design specifications, and they were better than those characterized from the gravity cast wax. A numerical model of growth and dissolution of bubbles during the process was then developed to predict the quality of the castings. The numerical results showed how increasing the mold rotational speed up to 1800 rpm reduced the removal time. However, compared to grains solidification time, the predicted removal times were much shorter, proving the advantage of centrifugal casting in counteracting voids formation. [ABSTRACT FROM AUTHOR]