8985111
AI Planning Versus Manufacturing-Operation Planning: A Case Study
Although AI planning techniques can potentially be useful in several manufacturing domains, this potential remains largely unrealized. In order to adapt AI planning techniques to manufacturing, it is important to develop more realistic and robust ways to address issues important to manufacturing engineers. Furthermore, by investigating such issues, AI researchers may he able to discover principles that are relevant for AI planning in general. As an example, in this paper we describe the techniques for manufacturing-operation planning used in IMACS (Interactive Manufacturability Analysis and Critiquing System), and compare and contrast them with the techniques used in classical AI planning systems. We describe how one of IMACS's planning techniques may be useful for AI planning in general--and as an example, we describe how it helps to explain a puzzling complexity result in AI planning.
12219775
Geometric algorithms for containment analysis of rotational parts
Abstract This paper describes a system and underlying algorithms to perform geometric containment analysis to determine if a newly designed rotational part can be manufactured from a part in an existing database of rotational parts. Only material removal of the database part is considered in order to obtain the newly designed part from the database part. The system uses a three-step algorithm to test for containment. The first step analyzes feasibility of containment using bounding cylinders. If the bounding cylinder of the query part is bigger than the part in the database, then the database part cannot contain the query part and it is eliminated from consideration. The second step analyzes feasibility of containment by ignoring off-axis features. Any part that fails to satisfy containment at this stage is eliminated from consideration. The third step analyzes the remaining parts from the database for feasibility of containment by including the off-axis features. Finally, the system rank-orders all the database parts that can contain the query part based on their volume differences with the query part. The system described in this paper can be used by designers and process planners to find an existing part that can be used as a stock to manufacture a newly designed part. This capability is expected to significantly reduce proliferation of parts, to improve manufacturing responsiveness, and to reduce the cost of new products.
532672
IMACS: A Case Study in Real-World Planning
This article discusses the complexities of real-world planning and how to create planning systems to address them. IMACS (Interactive Manufacturability Analysis and Critiquing System), an automated designer's aid, evaluates machined parts and suggests design modifications to improve their manufacturability, offering advantages over the planning techniques used in classical planning systems.
13998462
Geometric algorithms for computing cutter engagement functions in 2.5D milling operations
Cutter engagement is a measure that describes what portion of the cutter is involved in machining at a given instant of time. During profile milling of complex geometries, cutter engagement varies significantly along the cutter path. Cutter engagement information helps in determining the efficiency of the cutter path and also helps in improving it by adjusting the feed rate. This paper describes geometric algorithms for computing piece-wise continuous closed-form cutter engagement functions for 2.5D milling operations. The results produced by our algorithm are compared with the results obtained by discrete simulations of the cutting process and appear to match very well.
6821018
Concurrent evaluation of machinability during product design
An approach to evaluating the machinability of a part during the design stage, which performs systematic generation and evaluation of machining alternatives, is discussed. The results of the analysis provide feedback to the designer about problems that might arise with the machining and information to the manufacturing engineer about which machining processes and process parameters are most desirable.<<ETX>>
7211906
Manufacturing feature instances: which ones to recognize?
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 scientific and mathematical framework. One challenge is the issue of alternatives in feature-based planning. Even after one has decided upon an abstract set of features to use for representing manufacturing operations, the set of feature instances used to represent a part is by no means unique. For a complex part, many (sometimes infinitely many) different manufacturing operations can potentially be used to manufacture various portions of the part. Some of these feature instances will appear in useful manufacturing plans, and others will not. In order to reduce the number of alternative manufacturing plans that must be examined, we require a systematic means of specifying which feature instances are of interest. This paper addresses the issue of alternatives by introducing the notion of primary feature instances, which we contend are sufficient to generate all manufacturing plans of interest. To substantiate our argument, we describe how various instances in the primary feature set can be used to produce the desired plans. Furthermore, we discuss how this formulation overcomes computational difficulties faced by previous work, and present some complexity results for this approach in the domain of machined parts. “Also with: Nationaf Institute of Standards and Technology, Manufacturing Systems Integration Division Building 220, Room A-127, Gaithersburg, MD 20899. Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advanta$e, the ACM copyright notice and the title of the publication and Its date appear, and notice is given that copying is by permission of the Association of Computing Machinery.To copy otherwise, or to republish, requires a fee and/or specific permission. Solid Modeling ’95, Salt Lake City, Utah USA
1533259
Coordinated transformations for high-level synthesis of high performance microprocessor blocks
High performance microprocessor designs are partially characterized by functional blocks consisting of a large number of operations that are packed into very few cycles (often single-cycle) with little or no resource constraints but tight bounds on the cycle time. Extreme parallelization, conditional and speculative execution of operations is essential to meet the processor performance goals. However, this is a tedious task for which classical high-level synthesis (HLS) formulations are inadequate and thus rarely used. In this paper, we present a new methodology for application of HLS targeted to such microprocessor functional blocks that can potentially speed up the design space exploration for microprocessor designs. Our methodology consists of a coordinated set of source-level and fine-grain parallelizing compiler transformations that targets these behavioral descriptions, specifically loop constructs in them and enables efficient chaining of operations and high-level synthesis of the functional blocks. As a case study in understanding the complexity and challenges in the use of HLS, we walk the reader through the detailed design of an instruction length decoder drawn from the Pentium®-family of processors. The chief contribution of this paper is formulation of a domain-specific methodology for application of high-level synthesis techniques to a domain that rarely, if ever, finds use for it.
118731
A theoretical study of optimization techniques used in registration area based location management: models and online algorithms
We describe a study of optimization techniques which have been proposed in the literature for registration area based location management from the perspective of optimal on-line algorithms. We show that most of these optimization techniques such as forwarding pointers and overlapped registration areas can be modeled using metrical task systems. Some of these models are simple while others are somewhat intricate. These representations directly imply the applicability of existing results on metrical task systems to algorithm design for location management. However, this also means that general lower bounds known for online metrical task systems carry over to our formulations of location management. We also discuss some restricted models in which much better (and simpler) algorithms are possible.
16692732
Versioned Hypermedia can improve software document management
This research was supported by the U. S. Department of Defense and by NSF CAREER award CCR-9734102. The Software Concordance project is addressing the software document management problem by providing a fine-grained version control model for software documents and their relationships using hypermedia versioning. A set of tools needed to maintain, visualize and analyze software documents is being constructed. This short paper presents research issues, initial results and a scheme for using hypermedia versioning and time stamps to automate detection of possible semantic non-conformance among software artifacts.
2982914
Network topology exploration of mesh-based coarse-grain reconfigurable architectures
Several coarse-grain reconfigurable architectures proposed recently consist of a large number of processing elements (PEs) connected in a mesh-like network topology. We study the effects of three aspects of network topology exploration on the performance of applications on these architectures: (a) changing the interconnection between PEs; (b) changing the way the network topology is traversed while mapping operations to the PEs; and (c) changing the communication delays on the interconnects between PEs. We propose network topology traversal strategies that first schedule PEs that are spatially close and that have more interconnections among them. We use an interconnect aware list scheduling heuristic as a vehicle to perform the network topology exploration experiments on a set of designs derived from DSP applications. Our experimental results show that a spiral traversal strategy, coupled with a two neighbor interconnect topology leads to good performance for the DSP benchmarks considered. Our prototype framework thus provides an exploration environment for system architects to explore and tune coarse-grain reconfigurable architectures for particular application domains.
1499493
Bandwidth-Optimal Complete Exchange on Wormhole-Routed 2D/3D Torus Networks: A Diagonal-Propagation Approach
All-to-all personalized communication, or complete exchange, is at the heart of numerous applications in parallel computing. Several complete exchange algorithms have been proposed in the literature for wormhole meshes. However, these algorithms, when applied to tori, cannot take advantage of wrap-around interconnections to implement complete exchange with reduced latency. In this paper, a new diagonal-propagation approach is proposed to develop a set of complete exchange algorithms for 2D and 3D tori. This approach exploits the symmetric interconnections of tori and allows to develop a communication schedule consisting of several contention-free phases. These algorithms are indirect in nature and they use message combining to reduce the number of phases (message start-ups). It is shown that these algorithms effectively use the bisection bandwidth of a torus which is twice that for an equal sized mesh, to achieve complete exchange in time which is almost half of the best known complete exchange time on an equal sized mesh. The effectiveness of these algorithms is verified through simulation studies for varying system and technological parameters. It is also demonstrated that synchronous implementations of these algorithms (by introducing barriers between phases) lead to reduced latency for complete exchange with large messages, while the asynchronous ones are better for smaller messages.