Modular System Design Research Articles

Integrated planning for product module selection and assembly line design/reconfiguration

To take full advantage of product modularity, modular product design and assembly system design/sreconfiguration have to be simultaneously addressed. The emerging reconfigurable production and flexible assembly techniques have made such an integrated approach possible. As such, this paper proposes an integrated approach to product module selection and assembly line design/reconfiguration problems. It further suggests that quality loss functions be used in a generic sense to quantify non-comparable and possibly conflicting performance criteria involved in the integrated problem. The complexity of the problem precludes the use of commercial software for solving meaningful sized problems in polynomial time. A genetic algorithm is therefore developed to provide quick solutions. An example problem is solved to illustrate the application of the proposed approach. Based on 72 randomly generated test problems, ANOVA analysis is further carried out to investigate the effects of genetic algorithm parameters. The convergence behaviour of the search processes is also examined by solving large problems with different numbers of operations and product modules.

Compositional modeling and refinement for hierarchical hybrid systems

In this paper, we develop a theory of modular design and refinement of hierarchical hybrid systems. In particular, we present compositional trace-based semantics for the language C haron that allows modular specification of interacting hybrid systems. For hierarchical description of the system architecture, C haron supports building complex agents via the operations of instantiation, hiding, and parallel composition. For hierarchical description of the behavior of atomic components, C haron supports building complex modes via the operations of instantiation, scoping, and encapsulation. We develop an observational trace semantics for agents as well as for modes, and define a notion of refinement for both, based on trace inclusion. We show this semantics to be compositional with respect to the constructs in the language.

Knowledge-intensive collaborative design modeling and support: Part I: Review, distributed models and framework

Contemporary design problems embody significant levels of complexity, which make it unlikely that a single designer can work alone on a complex design problem. Knowledge-intensive collaboration has emerged as a promising discipline for dealing with the modeling and decision-making processes in distributed design systems. In this paper, we first review previous work and current research status of knowledge-intensive collaborative design. Then, we develop knowledge-intensive distributed design models and a framework for collaborative design modeling and decision support. Based on the component-based modeling/design approach, a unified design-with-modules scheme is proposed to model the distributed network-centric design processes, and a web-based knowledge-intensive distributed module modeling and evaluation framework (KS-DMME) is developed. The KS-DMME framework intends to link distributed, heterogeneous knowledge-based design models and tools and assist designers in evaluating design alternatives, visualizing trade-offs, finding optimal solutions, and making decisions on the web. It also enables designers to build integrated design models using both the local and distributed resources and cooperate by exchanging services. Built on it, the client (browser)/knowledge server architecture allows product design models to be published and connected over the WWW to form an integrated intelligent models/modules network. Finally, as an illustration, a simple design problem model for modular micro-robotic systems design is built upon the KS-DMME framework.

Self-Assembly of Model DNA-Binding Peptide Amphiphiles

Peptide amphiphiles combine the specific functionality of proteins with the engineering convenience of synthetic amphiphiles. These molecules covalently link a peptide headgroup, typically from an active fragment of a larger protein, to a hydrophobic alkyl tail. Our research is aimed at forming and characterizing covalently stabilized, self-assembled, peptide-amphiphile aggregates that can be used as a platform for the examination and modular design and construction of systems with engineering biological activity. We have studied the self-assembly properties of a model DNA-binding amphiphile, having a GCN4 peptide as the headgroup and containing a polymerizable methacrylic group in the tail region, using a combination of small-angle X-ray scattering, small-angle neutron scattering, and cryo- transmission electron microscopy. Our results reveal a variety of morphologies in this system. The peptide amphiphiles assembled in aqueous solution to helical ribbons and tubules. These structures transformed into lamella upon DNA binding. In contrast with common surfactants, the specific interaction between the headgroups seems to play an important role in determining the microstructure. The geometry of the self-assembled aggregate can be controlled by means of adding a cosurfactant. For example, the addition of SDS induced the formation of spherical micelles.

The role of web-based environmental information in urban planning—the environmental information system for planners

The Environmental Information System for Planners (EISP) is a proof of concept web-based system designed to support decision making within the UK planning framework by making information on environmental issues more widely accessible. It incorporates relevant outputs from the Natural Environment Research Council (NERC) Urban Regeneration and the Environment (URGENT) research programme and from research directly commissioned by the Office of the Deputy Prime Minister (ODPM). It supports three principal planning functions carried out by local authorities: pre-planning enquiries, development control decisions and strategic planning. Eleven environmental science themes are incorporated: Air quality, Shallow undermining, Landslide susceptibility, Groundwater protection, Flood risk, Drainage, Land contamination, Proximity to landfill, Biodiversity, Natural and Man-made heritage. Decision flow diagrams represent detailed analysis of workflow in each theme, taking account of best practice, regulatory responsibilities and planning guidance. Industry-standard web technologies integrate the flows and provide access to the system via secure web pages. Underpinning the system is an environmental geographical information system (GIS) containing up-to-date data, information and models relevant to each theme. The modular system design allows new legislation and local priorities and datasets to be easily incorporated. Web technology delivers information and research data that have hitherto been difficult for the non-specialist to access and have therefore been under-exploited. The study has demonstrated a successful application of the principles of e-Governance in an area where informed decisions commonly require specialist information. The system, if rolled out nationally, offers potential economic benefits and efficiency savings for both planners and developers.

Fluoroscopy-Based 3-D Reconstruction of Femoral Bone Cement: A New Approach for Revision Total Hip Replacement

In revision total hip replacement the removal of the distal femoral bone cement can be a time consuming and risky operation due to the difficulty in determining the three-dimensional (3-D) boundary of the cement. We present a new approach to reconstruct the bone cement volume by using just a small number of calibrated multiplanar X-ray images. The modular system design allows the surgeon to react intraoperatively to problems arising during the individual situation. When encountering problems during conventional cement removal, the system can be used on demand to acquire a few calibrated X-ray images. After a semi-automatic segmentation and 3-D reconstruction of the cement with a deformable model, the system guides the surgeon through a free-hand navigated or robot-assisted cement removal. The experimental evaluation using plastic test implants cemented into anatomic specimen of human femoral bone has shown the potential of this method with a maximal error of 1.2 mm (0.5 mm RMS) for the distal cement based on just 4-5 multiplanar X-ray images. A first test of the complete system, comparing the 3-D-reconstruction with a computed tompgraphy data set, confirmed these results with a mean error about 1 mm.

Modular design and verification of component-based mechatronic systems with online-reconfiguration

The development of complex mechatronic systems requires a careful and ideally verifiable design. In addition, engineers from different disciplines, namely mechanical, electrical and software engineering, have to cooperate. The current technology is to use block diagrams including discrete blocks with statecharts for the design and verification of such systems. This does not adequately support the verification of large systems which improve the system behavior at run-time by means of online reconfiguration of its controllers because the system as whole has to be verified. It also does not support cooperative interdisciplinary work because a white-box view on all blocks involved in the online reconfiguration is required. This paper proposes a rigorous component concept based on the notion of UML component diagrams which enables modular composition and decomposition of complex systems with online reconfiguration given by hierarchical hybrid component specifications. The approach enables compatibility checks between components that are often independently developed (across the different disciplines) and supports compositional model checking based on a rigorously defined semantics.

Towards Web‐enabled design of modular assembly systems

The development of reconfigurable modular production systems is one of the crucial factors for manufacturers to sustain their competitive advantage in areas such as precision assembly. To ensure the effective and cost efficient configuration and successive reconfigurations it is of critical importance to involve all stakeholders in the decision‐making process. The reported research is targeting the development of an integrated Web‐enabled decision‐making environment that supports some of the key assembly system engineering stages from user requirement specification to system implementation. The focus is on the design of assembly workstations based on detailed process requirements with a target of developing highly efficient and cost‐effective solutions. The paper presents an application framework for collaborative distributed design supported by domain ontologies and is illustrated using an industrial case study.

Medium-Power Lead-Alloy Reactors: Missions for This Reactor Technology

A multiyear project at the Idaho National Engineering and Environmental Laboratory and the Massachusetts Institute of Technology investigated the potential of medium-power lead-alloy–cooled technology to perform two missions: (1) the production of low-cost electricity and (2) the burning of actinides from light water reactor (LWR) spent fuel. The goal of achieving a high power level to enhance economic performance simultaneously with adoption of passive decay heat removal and modularity capabilities resulted in designs in the range of 600-800 MW(thermal), which we classify as a medium power level compared to the lower [˜100 MW(thermal)] and higher [2800 MW(thermal)] power ratings of other lead-alloy–cooled designs. The plant design that was developed shows promise of achieving all the Generation-IV goals for future nuclear energy systems: sustainable energy generation, low overnight capital cost, a very low likelihood and degree of core damage during any conceivable accident, and a proliferation-resistant fuel cycle. The reactor and fuel cycle designs that evolved to achieve these missions and goals resulted from study of the following key trade-offs: waste reduction versus reactor safety, waste reduction versus cost, and cost versus proliferation resistance. Secondary trade-offs that were also considered were monolithic versus modular design, active versus passive safety systems, forced versus natural circulation, alternative power conversion cycles, and lead versus lead-bismuth coolant.These studies led to a selection of a common modular design with forced convection cooling, passive decay heat removal, and a supercritical CO2 power cycle for all our reactor concepts. However, the concepts adopt different core designs to optimize the achievement of the two missions. For the low-cost electricity production mission, a design approach based on fueling with low enriched uranium operating without costly reprocessing in a once-through cycle was pursued to achieve a long operating cycle length by enhancing in-core breeding. For the actinide-burning mission three design variants were produced: (1) a fertile-free actinide burner, i.e., a single-tier strategy, (2) a minor actinide burner with plutonium burned in the LWR fleet, i.e., a two-tier strategy, and (3) an actinide burner with characteristics balanced to also favor economic electricity production.

Scalable multichannel MRI data acquisition system

A scalable multichannel digital MRI receiver system was designed to achieve high bandwidth echo-planar imaging (EPI) acquisitions for applications such as BOLD-fMRI. The modular system design allows for easy extension to an arbitrary number of channels. A 16-channel receiver was developed and integrated with a General Electric (GE) Signa 3T VH/3 clinical scanner. Receiver performance was evaluated on phantoms and human volunteers using a custom-built 16-element receive-only brain surface coil array. At an output bandwidth of 1 MHz, a 100% acquisition duty cycle was achieved. Overall system noise figure and dynamic range were better than 0.85 dB and 84 dB, respectively. During repetitive EPI scanning on phantoms, the relative temporal standard deviation of the image intensity time-course was below 0.2%. As compared to the product birdcage head coil, 16-channel reception with the custom array yielded a nearly 6-fold SNR gain in the cerebral cortex and a 1.8-fold SNR gain in the center of the brain. The excellent system stability combined with the increased sensitivity and SENSE capabilities of 16-channel coils are expected to significantly benefit and enhance fMRI applications.

Virtual development of the BMW Z4 cooling system

Autumn 2002 saw the launch of the new BMW Z4 roadster, initially in the USA, with the familiar 2.5-l and 3.0-l in-line six-cylinder spark-ignition engines. The cooling system was based on the modular design system used for the current 3 Series, but adapted to match the Z4’s specific requirements. As on the vehicle as a whole, consistent use of simulation techniques played a decisive part in the development of the cooling system.

使用済み燃料横型サイロ貯蔵施設の基本設計

横型サイロ貯蔵施設は, 米国で実用化された軽水炉の使用済み燃料乾式貯蔵システムであり, 我が国の使用済み燃料中間貯蔵施設の候補概念の一つであることから, 経済性向上, 日本の安全審査指針・技術基準, 貯蔵燃料の仕様, 耐震条件等との適合性を考慮して, 我が国向けの横型サイロ貯蔵施設の開発を進めてきた． 横型サイロ貯蔵施設の設計に当たっては, 日本の条件に適合させるため, 除熱性向上, 遮へい性能向上, 耐震性向上および貯蔵密度向上の改良を行った．また, キャニスタ内伝熱流動実験を実施し, キャニスタ内のヘリウムの自然対流が使用済み燃料の除熱に寄与し, また, キャニスタ内圧を高めることで効果が促進されることを確認した．この結果より, キャニスタにはヘリウムを充填し, 加圧することとし, 設計に反映した． 米国での実績に加え, 本研究の成果により横型サイロ貯蔵方式の使用済み燃料貯蔵施設の日本での適合性を確認できた．

Research on flexible transfer line schematic design using hierarchical process planning

This paper proposes an approach to a bidding-based flexible transfer line (FTL) schematic design system. The architecture of the flexible transfer line schematic design system (FTLSDS) is established. The system consists of four processes: part feature modeling, process planning, FTL facility layout and FTL evaluation. For FTL schematic design, a five-level process planning strategy named the hierarchical process planning method is proposed. This method includes the selection of the manufacturing feature machining operation, part set-up planning, feature sequencing, operation sequencing and process plan generating. The major decision relies on set-up planning. The framework of the machine modular design system to support machine requirement design for FTL is implemented. In the process of evaluation, quality, flexibility, reliability, machine load, and cost are taken into account.

Design, Specification, Installation, and Maintenance of Modular Bridge Expansion Joint Systems

Data regarding service performance and durability of modular bridge expansion joint systems were gathered through a comprehensive literature review, survey of transportation agencies, and field observations. Typical service life and desired service life targets are discussed. Maximum movement and rotation demands are given with respect to three axes. Performance and durability problems include problems that can be traced to poor design and/or installation, wear and tear of elastomeric parts, and fastener loosening and fatigue cracking of the metal parts. Fatigue cracking has been addressed in previous research. Guidance on design, detailing, specifications, installation, and maintenance is discussed, which should reduce the problems in the first group. Problems with the elastomeric parts and fasteners are best addressed through performance tests on the modular bridge joint systems as a system. Two system performance tests, an opening movement/vibration test, and a seal push-out test are suggested for the prequalification of specific modular bridge expansion joint systems.

Development of modular electrical systems

Modular systems provide the ability to achieve product variety through the combination and standardization of components. A methodology that combines system modeling, integration analysis, and optimization techniques for development of modular systems is presented. The approach optimizes integration and interactions of system elements and creates functional and physical modules for the electrical system. The Hatley/Pirbhai methodology (1987) is used for modeling functional requirements of a system. The model defines system interfaces (interactions) to support its functions. Once the interactions among functions are identified, an incidence matrix of the interfaces is developed. A clustering algorithm is developed to identify clusters in the incidence matrix, group the functions, and create modules. A Hatley/Pirbhai architecture model is developed to represent modular system design. A detailed discussion on the importance of system modeling in design of modular systems and on the constraints that limit development of modular vehicle systems is also presented. The approach presented is systematic and can be used to support product development and decision-making in engineering design.

On Modular Design of Field Robotic Systems

Robots are needed to perform important field tasks such as hazardous material clean-up, nuclear site inspection, and space exploration. Unfortunately their use is not widespread due to their long development times and high costs. To make them practical, a modular design approach is proposed. Prefabricated modules are rapidly assembled to give a low-cost system for a specific task. This paper described the modular design problem for field robots and the application of a hierarchical selection process to solve this problem. Theoretical analysis and an example case study are presented. The theoretical analysis of the modular design problem revealed the large size of the search space. It showed the advantages of approaching the design on various levels. The hierarchical selection process applies physical rules to reduce the search space to a computationally feasible size and a genetic algorithm performs the final search in a greatly reduced space. This process is based on the observation that simple physically based rules can eliminate large sections of the design space to greatly simplify the search. The design process is applied to a duct inspection task. Five candidate robots were developed. Two of these robots are evaluated using detailed physical simulation. It is shown that the more obvious solution is not able to complete the task, while the non-obvious asymmetric design develop by the process is successful.

Mapping UML designs to Java

Tools for the generation of code from model descriptions are valuable in helping developers maintain consistency between a model and its implementation. In this paper, we describe a new method for generating Java implementation code from UML diagrams. Our method accepts UML diagrams specified at a higher-level than current tools, and places fewer constraints on the supported UML constructs, like multiple generalizations and association classes. Unlike current tools, it generates implementation code that shields system implementers from the low-level details of how associations and other UML constructs are mapped to Java. Furthermore, it supports the modular design of systems according to concerns[2, 10] by being able to generate code from a set of related UML diagrams. While our discussion is focused on the special problem of generating Java implementation code, the issues discussed in this paper are applicable more generally to object-oriented implementation languages.

An automated design and assembly of interference-free modular fixture setup

This paper describes an automated modular fixture design system developed using a CAD-based methodology and implemented on a 3-D CAD/CAM software package. The developed automated fixture design (AFD) system automates the fixturing points determination and is integrated on top of the previously developed interactive and semi-automated fixture design systems. The determination of fixturing points is implemented in compliance with the fixturing principles that are formulated as heuristics rules to generate candidate list of points and then select the exact points from the list. Apart from determining the fixturing points automatically, the system is capable of producing cutting tool collision-free fixture design using its machining interference detection sub-module. The machining interference detection is accomplished through the use of cutter swept solid based on cutter swept volume approach. Therefore, using the developed AFD, an interference-free fixture design and assembly can be achieved in the possible shortest design lead-time.

An Integrated Approach to Collision-Free Computer-Aided Modular Fixture Design

This paper describes a CAD-based methodology for developing a modular fixture design system using the Unigraphics (UG) solid modeller, integrated with a modular fixture element database, based on a hole-based IMAO modular fixturing system. A parametric modelling technique has been applied to construct the database. An integrated methodology is introduced in the system in which the functions of interactive, semi-automated and automated fixture design systems are combined collaboratively in a single environment. This provides the flexibility and functionality for making the design process more efficient. The interactive fixture design module helps the designer to select the fixturing faces, points and elements for building a fixture. Semi-automated and automated fixture design modules are built by transforming the designers' experience and knowledge into rules and algorithms to automate the selection of fixturing points and elements, More importantly, the system aims at producing a tool-collision-free fixture design using a machining interference detection submodule based on a cutter swept volume approach.

Towards the design and development of a knowledge-based universal modular jigs and fixtures system

Jigs and fixtures are one of the important aspects of manufacturing. Parts may have different sets of fixturing requirements and call for different design strategies. Although there are numerous possibilities for fixture designs, a few basic configurations are clearly identifiable. Computer aided design (CAD) has done a little in assisting designers to design jigs and fixtures, making decisions of the best design selection, and providing designers with suggestions. The goal of this paper is to develop and document the design parameters and specifications utilized in jigs and fixtures design using universal modular jigs and fixtures design system (UMJFS). This is the first step to develop a knowledge-based Jigs and Fixture design and selection system. This application has the advantages of making the fixture design information completely modular and transparent, providing better match to the working conditions, reducing lead-time, and generally providing a significant enhancement of fixture productivity and economy. UMJFS has different standard and modular elements. This makes jigs and fixtures elements interchangeable and reusable. Designing a UMJFS then becomes a task of selecting and assembling the proper elements together.