Manufacturing Engineering

Plasma etch is a complex semiconductor manufacturing process in which material is removed from the surface of a silicon wafer using a gas in plasma form. As the process etch rate cannot be measured easily during or after processing, virtual metrology is employed to predict the etch rate instantly using ancillary process variables. Virtual metrology is the prediction of metrology variables using other easily accessible variables and mathematical models. This paper investigates the use of Gaussian process regression as a virtual metrology modelling technique for plasma etch data.

The effect of Fe, Cu, Zr, and Ti substitution on magnetic properties of SmCo 1 : 7 magnets at temperatures up to 500 degreesC were studied. As-milled amorphous Sm(Co,Fe,Cu,Ti-Zr)(7) magnets crystallized in the TbCu7-type structure after annealing at 750 degreesC for 2 h. A room-temperature intrinsic coercivity of around 2.5 T is obtained for compositions SmCo6.4 Zr-0.2 Ti-0.4 and SmCo6.4Fe0.1Zr0.1Ti0.4. The high coercivity of the ball-milled SmCo7-xTix magnets is attributed to the strong pinning of the walls of the "interaction domains" by the network of grain boundaries between the nanocrystalline grains. The virgin curve of the ball-milled samples is suggestive of strong domain wall pinning.

Sporting shoes, in particular those for
running, must fulfill two requirements: on one hand they
must assure the maximum utilization of the biomechanical
energy, while on the other hand they must protect the athlete
from functional overload pathologies due to isolated trauma
or by repeated microtraumas over time. To satisfy these
conditions, materials or devices must able not only to reduce
the maximum values of the impact strength, but also absorb
the micro-vibrations. The damping cannot be excessive
because it negatively affects the athletic performance;
therefore there is the need to reach a compromise between
two opposite demands; this can be achieved using smart
fluids able to modify in real time the damping coefficient
according to needs. Thereby to design a running shoe with an
active damping system based on magnetorheological (MR)
fluids it is necessary first of all to know the viscoelastic and
damping properties of the fluid. We have studied the
characteristics of the MR fluid made in our laboratory, with
a reference comparison with commercial MR fluids. We have
chosen to prepare the fluid ourselves because in this way we
have been able to determine the influence of each element of
the MR fluid. These preliminary results seem to show
promise for MR fluids for this kind of application; for the
future the target is improve their properties and develop an
efficient prototype for preindustrial application.

Simulation modelling has been identified as one of the most powerful techniques available for the analysis and design of complex manufacturing systems. A number of manufacturing simulators have been designed in an effort to make it easier to use the simulation approach in the manufacturing environment. This paper will attempt to describe and evaluate the
characteristics of some of the available manufacturing simulators as well as possible ways to alleviate some of the inherent disadvantages. This paper will also report on the preliminary design philosophy and specifications of a manufacturing simulation program generator (FACSIM) presently under
development.

In this paper we intend to recreate an interactive 3D virtual version of the real environment of a mobile robot and to ensure a bi- directional interaction with all the components of this workplace. This IVW ( interactive virtual world), automatically built using VRML combined with Java, is actualized on line with 3D models of the objects present in the real workplace. Internet interaction between any remote operator and the IVW is ensured by a Java based virtual interface and may be used, as well to teleoperate the robot. The presented approach is applied to PIONEER 2 and LABMATE mobile robots. Copyright © 2002 IFAC

This paper introduces and describes a mechanism for manufacturing robotic arm like human arm and its control method. At first a mechanical design of this robot that is inspired by a demonstration of the exact dimensions of its fingers is presented here. Especially, we assume a virtual steering system for the motion of fingers to grasp and retain its normal state. Secondly an explanation of the mechanism of its proper functioning based on slider, spring and string combination that enables the joints of the finger to move and lock in desired position is described. Of course, it is also possible for the joints to unlock themselves by a reverse mechanism. The detailed design and properties of the robotic arm are described in this paper. Keywords: Robotic arm, Human arm, Finger, Grasp.

Modular and Reconfigurable Robots (MRR) are a breed of industrial robots designed for today’s flexible and versatile production facilities. MRRs can be assembled in various ways to achieve numerous distinct Kinematic configurations (KC). In MRRs, the problem of finding the most suitable KC for a specific task from a predefined set of modules is called Task-based Configuration Optimization (TBCO). To assess a KC in TBCO, a solution to the Inverse Kinematics (IK) problem is required.

In this paper, a TBCO algorithm based on Genetic Algorithms (GA) is proposed that utilizes a multi-solution IK solver. By solving for multiple solutions of the IK, the possibility of preferring a sub-optimal KC over an optimal configuration is decreased. Moreover, in the proposed TBCO algorithm a priority based GA Selection operator is used to ensure reaching the right solution in case of more than one optimization criteria.

In this paper, an analytical modeling has been carried out to realize the effect of appending a supplementary percussive load to the rotary energy of tunnel boring machine's disc cutters, as a novel technology. In this path, two models have been built by using the theory of plasticity for prediction of the amount of penetration of a disc cutter assumed in form of a V-shaped indenter in rock medium. Since the types of applied loads at two phases (rotary versus percussive) differ, it was obligatory to consider different analytical models for each phase. At first stage of the modeling process, a part of previously constructed model for determination of tool penetration into rock has been used. Then, at the next stage, the depth of penetration resulted from the impacts of a striker on the disc cutter has been modeled by using the kinematic method. The aggregative penetration of the disc by application of rotary-percussive load has been considered as non-algebraic summation of penetrations in two stages. Finally, an illustrative example has been presented to show the application of the models in a real situation. In both models, the friction between penetrating tool and the rock has been taken into account.

Product design engineering is undergoing a transformation from informal and largely experience-based discipline to a science-based domain. Computational intelligence offers models and algorithms that can contribute greatly to design formalization and automation. This paper surveys computational intelligence concepts and approaches applicable to product design engineering. Taxonomy of the surveyed literature is presented according to the generally recognized areas in both product design engineering and computational intelligence. Some research issues that arise from the broad perspective presented in the paper have been signaled but not fully pursued. No survey of such a broad field can be complete, however, the material presented in the paper is a summary of state-of-the-art computational intelligence concepts and approaches in product design engineering.

There are p heterogeneous objects to be assigned to n
competing agents (n > p) each with unit demand. It is
required to design a Groves mechanism for this assignment
problem satisfying weak budget balance, individual
rationality, and minimizing the budget imbalance. This calls
for designing an appropriate rebate function. Our main
result is an impossibility theorem which rules out linear
rebate functions with non-zero efficiency in heterogeneous
object assignment. Motivated by this theorem, we explore
two approaches to get around this impossibility. In the first
approach, we show that linear rebate functions with nonzero
efficiency are possible when the valuations for the
objects have some relationship. In the second approach,
we show that rebate functions with non-zero efficiency are
possible if linearity is relaxed.

Most of today’s environmental policies in Brazil rely on controlling the growth of pollution by “command and control” techniques. During the last two decades, these instruments have been designed to control sources of environmental impacts using industrial zoning, environmental licensing, and emission standards. The present structure of environmental law and policy focuses almost entirely on the activities of manufacturing companies and does not recognize strategies related to pollution prevention and/or cleaner production — such as product life cycle assessment, environmental labeling, environmental management systems, interconnectivity of production process, extended producer responsibility strategy, and environmental certification — as important instruments for auto-regulation. Recognizing that environmental policy must become more focused on “command and covenant” than “command and control”, this article attempts to provide an expanded perspective of environmental policy innovation based on a more holistic approach — Industrial Ecology — as a strategic tool for environmental policy-making process in Brazil.

An Engineering Employers Federation report recently stated that US-owned manufacturers in the UK are gaining a competitive advantage through greater application of lean manufacturing. Brian Swain and Alan Mossman of Rubicon Associates describe an effective lean transformation at Hathaway Roofing in County Durham

One of the main problems in ERP implementation projects is how to align an off-the-shelf software package with the business
processes of the enterprise implementing it. The paper proposes a requirement-driven approach, which benefits from reusing the business process design without being restricted by predefined solutions and criteria. The approach applies an iterative alignment process, which employs an algorithm that matches a model of the enterprise requirements with a model of the ERP system capabilities. The algorithm identifies possible matches between the two models and evaluates the gaps between them despite differences in their completeness and detail level. It provides the enterprise with a set of feasible combinations of requirements that can be satisfied by the ERP system as a basis for making implementation decisions. We use Object-Process Methodology (OPM) to model both the ERP system and the enterprise requirements, and utilize the pair of resulting OPM models as input for the matching algorithm. The alignment algorithm has been tested in an experimental study, whose encouraging results demonstrate the ability of the approach to provide a satisfactory solution to the problem of aligning an ERP software package with an enterprise business model.

(c) 2005 Elsevier B.V. All rights reserved.

Keywords: Enterprise Resource Planning; Requirement-driven; Similarity; Business process design

The effect of the cooling rate on hardness and thermal conductivity in a metallurgical Jominy bar made of AISI 1018 steel, by means of a water end-quenched heat treatment process without diffusion-controlled case depth, is studied with photothermal radiometry (PTR). It is concluded that our two PTR techniques, common-mode rejection demodulation (CMRD) and conventional 50% duty-cycle square-wave frequency scan, are sensitive to low hardness values and gradients, unlike the high values all previous photothermal studies have dealt with to-date. Both PTR methods have yielded an anti-correlation between thermal conductivity and microhardness in this case as in previous cases with heat-treated and diffusion-controlled case depth profiles. It is shown that the cooling rate strongly affects both hardness and thermal conductivity in the Jominy-bar heat-treating process. © EDP Sciences.

We present a formula for a stabilizing feedback law under the assumption that a piecewise smooth control-Lyapunov function exists. The resulting feedback is continuous at the origin and smooth everywhere except on a hypersurface of codimension 1. We provide an explicit and "universal" formula. Finally, we mention a general result connecting asymptotic controllability and the existence of control-Lyapunov functions in the sense of nonsmooth optimization.

Defense computing applications are often highly demanding in terms of performance, reliability and security. While hardware has been improving at a rapid rate such that these demands may eventually be met, system software is still an impediment. To address this problem, we make the case for a new system software architecture, based on mobile agents and network (and distributed) computing. In this architecture, soldiers, aircraft, ships, and tanks, are not isolated objects that attach themselves to a network to communicate or obtain computing support only when necessary. Rather, they are an integral part of the network from the start, and rely on the sharing of network resources to meet their communication and computational demands. For robustness, this architecture must take into account that networks and their resources do break down, and that there are inherent security risks when one relies on network communication. We argue that a mobile-agent computing architecture provides the necessary framework for addressing these problems while maintaining a "network as an integrated system" view.

Automated recognition of features from CAD models has been attempted for a wide range of application domains in mechanical engineering. However, the absence of a clear mathematical formalism for the problem has made it di cult to develop a general approach|and thus most of these methods are limited in scope.

The increasing focus on design for manufacturability (DFM) in research in concurrent engineering and engineering design is expanding the scope of traditional design activities in order to identify and eliminate manufacturing problems during the design stage. Manufacturing a product generally involves many different kinds of manufacturing activities, each having different characteristics. A design that is good for one kind of activity may not be good for another; for example, a design that is easy to assemble may not be easy to machine. One obstacle to DFM is the difficulty involved in building a single system that can handle the various manufacturing domains relevant to a design.

While automated recognition of features has been attempted for a wide range of applications, no single existing approach possesses the functionality required to perform manufacturability analysis. In this paper, we present a methodology for taking a CAD model of a part and extracting a set of machinable features that contains the complete set of alternative interpretations of the part as collections of MRSEVs (Material Removal Shape Element Volumes, a STEP-based library of machining features). The approach handles a variety of features including those describing holes, pockets, slots, and chamfering and lleting operations. In addition, the approach considers accessibility constraints for these features, has an worst-case algorithmic time complexity quadratic in the number of solid modeling operations, and modi es features recognized to account for available tooling and produce more realistic volumes for manufacturability analysis.

Manufacturing features and feature-based representations have become an integral part of research on manufacturing systems, largely due to their ability to model correspondences between design information and manufacturing operations. However, several research challenges still must be addressed in order to place feature technologies into a solid scienti c and mathematical framework. One challenge is the issue of alternatives in feature-based planning.

The availability of low-cost computational power is a driving force behind the growing sophistication of CAD software. Tools designed to reduce time-consuming build-test-redesign iterations are essential for increasing engineering quality and productivity. However, automation of the design process poses many di cult computational problems. As more downstream engineering activities are being considered during the design phase, guaranteeing reasonable response times within design systems becomes problematic. Design is an interactive process and speed is a critical factor in systems that enable designers to explore and experiment with alternative ideas during the design phase. Achieving interactivity requires an increasingly sophisticated allocation of computational resources in order to perform realistic design analyses and generate feedback in real time.

Automated recognition of features from CAD models has been attempted for a wide range of application domains. In this paper we address the problem of representing and recognizing a complete class of features in alternative i n terpretations for a given design.

Automating redesign of electro-mechanical artifacts presents many difficult problems to the developers of intelligent CAD systems. To address this need requires we identify new AI technologies for representation and planning and effectively apply them to the manufacturing problem. In this paper, we present the redesign problem and outline some of the critical points; presenting how to bring existing AI research to bear in creating more effective CAD tools.

Smooth integration of computer-aided design (CAD) and manufacturing (CAM) is vital for companies' survival in the present competitive marketplace. One key component in this effort is the representation of product designs in terms of features, elements that are semantically higher-level than the pure geometric elements typically used in CAD and CAM systems.

This paper presents our initial efforts to develop a systematic approach for assessing the similarity of solid models based on how they will be manufactured. The goal of this work is to develop methods that, given a solid model representing the design of a new product, query a product information database (of solid models, associated manufacturing plans, and related attributes) and identify existing designs with manufacturing plans similar to some reasonable plan for the new design-or useful as a starting point for creation of a new plan for the new design.

This paper describes the development of a process planning module for an integrated product and process design (IPPD) tool which automates the design and manufacture of microwave modules. Specifically, this paper presents a process template that is used to interface with multiobjective optimization techniques to create a planner that can consider alternative designs based on process yields, cost, and manufacturing and purchasing lead times. The integration of the planner and the tradeoff optimization modules provides the designer immediate feedback on cost and productivity through generation and evaluation of alternative designs early in the design stage.

This paper describes the process planning techniques we developed for use in an Integrated Product and Process Design (IPPD) tool for the design and manufacture of microwave transmit/receive modules. Given a collection of data about the design of a microwave module, the IPPD tool uses a combination of AI planning and OR tradeoff analysis to produce a collection of alternative designs and alternative process plans that have Pareto optimal values for manufacturing and purchasing lead time, process yield, cost, and number of suppliers. The IPPD tool provides facilities to enable the user to generate and examine these Pareto optimal alternatives in real time, in order to provide immediate feedback on how to modify the design to improve its cost and productivity.

A This paper describes the process planning techniques we developed for use in an Integrated Product and Process Design (IPPD) tool for the design and manufacture of microwave transmit/receive modules. Given a collection of data about the design of a microwave module, the IPPD tool uses a combination of AI planning and optimization-based tradeoff analysis to produce a collection of alternative designs and alternative process plans that have Pareto optimal values for manufacturing and purchasing lead time, process yield, cost, and number of suppliers. The IPPD tool provides facilities to enable the user to generate and examine these Pareto optimal alternatives in real time, in order to provide immediate feedback on how to modify the design to improve its cost and productivity.

This paper describes a new geometric algorithm to determine the largest feasible cutter size for 2-D milling operations to be performed using a single cutter. First is given a general definition of the problem as the task of covering a target region without interfering with an obstruction region. This definition encompasses the task of milling a general 2-D profile that includes both open and closed edges. Discussed next are three alternative definitions of what it means for a cutter to be feasible, with explanations of which of these definitions is most appropriate for the above problem. Then, a geometric algorithm is presented for finding the maximal cutter for 2-D milling operations, and the algorithm is shown to be correct.

The force-constancy hypothesis states that the user of a force-feedback device maintains a constant penetration force when stroking virtual surfaces in order to perceive their topography. The hypothesis was developed to address a real-world data perceptualization problem where the perception of surface topography was distorted when the surface stiffness was nonuniform. Two experiments were conducted. In Experiment I, we recorded the penetration depths of the probe tip while the user stroked two surfaces with equal height but different stiffness values. We found that the data could be quantitatively modeled by the force-constancy hypothesis when the virtual surfaces were neither too soft nor too hard. In Experiment II, we demonstrated that given two adjacent surfaces, their perceived height difference depended on both the surface stiffness values as well as the relative heights of the surfaces. Specifically, we showed that the higher but softer surface could be perceived to be lower, at the same height, or higher than the other surface, depending on how much higher it was than the other surface. The results were consistent with the predictions of the force-constancy hypothesis. Our findings underscore the importance of understanding the interplay of haptic rendering parameters.

The dynamics of slender filaments or fibers suspended in Stokesian fluids are fundamental to understanding many flows arising in physics, biology and engineering. Such filaments can have aspect ratios of length to radius ranging from a few tens to several thousands. Full discretizations of such 3D flows are very costly. Instead, we employ a non-local slender body theory that yields an integral equation, along the filament centerline, relating the force exerted on the body to the filament velocity. This hydrodynamical description takes into account the effect of the filament on the fluid, and is extended to capture the interaction of multiple filaments as mediated by the intervening fluid. We consider filaments that are inextensible and elastic. Replacing the force in the slender body integral equation by an explicit expression that uses Euler-Bernoulli theory to model bending and tensile forces yields an integral expression for the velocity of the filament centerlines, coupled to auxiliary integro-differential equations for the filament tensions. Based on a regularized version of these slender body equations that is asymptotically equivalent to the original formulation, we construct a numerical method which uses a combination of finite differences, implicit time-stepping to avoid severe stability constraints, and special quadrature methods for nearly singular integrals. We present simulations of single flexible filaments, as well as multiple interacting filaments, evolving in a background shear flow. These simulations show shear induced buckling and relaxation of the filaments, leading to the storage and release of elastic energy. These dynamics are responsible for the development of positive first normal stress differences, commonly associated with visco-elastic fluids that are suspensions of microscopic elastic fibers.