11353497
Collision detection in aspect and scale bounded polyhedra
Let S be a family of n polyhedral objects in d dimensions, with aspect ratio bound CY and scale factor bound (T. Let K,(S) denote the number of object-pairs in S with nonempty intersection, and let &(S) denote the number of pairs whose enclosing balls intersect. We investigate the worst-case behavior of the following ratio: p(S) = Kb(s) n + I&(S). We establish almost-tight asymptotic bounds: p(S) = O(ofilog20), and p(S) = fl(a&). The important conclusion is that the ratio is independent of n, and if S has bounded aspect ratio and scale factor, the number of enclosing ball-pair intersections is about the same as the number of object-pair intersections. Our theorem implies the following two results. First, it lends strong theoretical support to a simple and practical heuristic for collision detection (the bounding box method), used in application domains such as computer graphics and robotics, where the objects typically have constant aspect ratio and scale factor. Second, it yields an output-sensitive algorithm for reporting all intersecting pairs in a set of n convex polyhedra with constant Q and cr. Our algorithm runs in time O(n logd-’ n + K, logdml n), for d = 2,3, where I~,, is the number of intersecting object pairs. This is significantly better than the bounds achieved by the previous algorithms, which make no assumptions about the aspect and scale factors.
7017581
Multi-finger cursor techniques
The mouse cursor acts as a digital proxy for a finger on graphical displays. Our hands, however, have ten fingers and many degrees of freedom that we use to interact with the world. We posit that by creating graphical cursors that reflect more of the hand's physical properties, we can allow for richer and more fluid interaction. We demonstrate this idea with three new cursors that are controlled by the user's fingers using a multi-point touchpad. The first two techniques allow for simultaneous control of several properties of graphical objects, while the third technique makes several enhancements to object selection.
795737
Navigating documents with the virtual scroll ring
We present a technique for scrolling through documents that is simple to implement and requires no special hardware. This is accomplished by simulating a hardware scroll ring--a device that maps circular finger motion into vertical scrolling. The technique performs at least as well as a mouse wheel for medium and long distances, and is preferred by users. It can be particularly useful in portable devices where screen-space and space for peripherals is at a premium.
2239491
Voice as sound: using non-verbal voice input for interactive control
We describe the use of non-verbal features in voice for direct control of interactive applications. Traditional speech recognition interfaces are based on an indirect, conversational model. First the user gives a direction and then the system performs certain operation. Our goal is to achieve more direct, immediate interaction like using a button or joystick by using lower-level features of voice such as pitch and volume. We are developing several prototype interaction techniques based on this idea, such as "control by continuous voice", "rate-based parameter control by pitch," and "discrete parameter control by tonguing." We have implemented several prototype systems, and they suggest that voice-as-sound techniques can enhance traditional voice recognition approach.
6477925
Constructive solid geometry for polyhedral objects
Constructive Solid Geometry (CSG) is a powerful way of describing solid objects for computer graphics and modeling. The surfaces of any primitive object (such as a cube, sphere or cylinder) can be approximated by polygons. Being abile to find the union, intersection or difference of these objects allows more interesting and complicated polygonal objects to be created. The algorithm presented here performs these set operations on objects constructed from convex polygons. These objects must bound a finite volume, but need not be convex. An object that results from one of these operations also contains only convex polygons, and bounds a finite volume; thus, it can be used in later combinations, allowing the generation of quite complicated objects. Our algorithm is robust and is presented in enough detail to be implemented.
6983775
Modeling surfaces of arbitrary topology using manifolds
Manifolds describe complicated objects that are locally $\Re\sp{n}$ by defining a set of overlapping maps from the object to $\Re\sp{n}$. In this thesis we present a general technique for inverting that process: we define a complicated object from a set of overlapping subsets of $\Re\sp{n}$. We first present a constructive definition that describes how to perform such a construction in general. We then apply this construction to the particular problem of defining surfaces of arbitrary topology. The surface is built in two steps: we build a manifold with the correct topology then embed the manifold into $\Re\sp3$ using traditional spline techniques. The surface inherits many of the properties of B-splines: local control, a compact representation, and guaranteed continuity of arbitrary degree. The surface is specified using a polyhedral control mesh instead of a rectangular one; the resulting surface approximates the polyhedral mesh much as a B-spline approximates its rectangular control mesh. Like a B-spline, the surface is a single, continuous object.
27941486
Distributed probabilistic diagnosis of MCMs on large area substrates
This paper addresses the issue of testing MCMs on large-area substrates. The cost of testing each MCM may be as high as 40% of the total manufacturing cost. It is critical that the test process be parallelized in order that multiple MCMs may be tested for the cost of testing one MCM. With this objective in mind, we propose a distributed probabilistic diagnosis algorithm for MCMs on large-area substrates. Our algorithm performs better than the existing diagnosis algorithms and can correctly identify almost all MCMs even when the yield is very low (35%). Further it provides upto an order of magnitude reduction in test application time as opposed to serial MCM probe test.
29935552
Optimal design of checksum-based checkers for fault detection in linear analog circuits
Traditionally, built-in self-test (BIST) techniques have assumed access to only the input and output nodes of the circuit under test (CUT). It has been shown earlier, that checksum-based checkers can be designed to perform on-line fault detection in linear analog circuits using access to certain internal nodes of CUT. In this paper, we address the problem of optimizing the checker circuitry to maximize the detectability of faults in CUT. The above optimization problem is solved as a linear programming problem. The resulting checker can be used to perform both BIST of CUT and on-line error detection as well. Faults in the checker hardware are taken into account during the checker optimization process.
16084483
Why Functional Programming Matters
As software becomes more and more complex, it is more and more important to structure it well. Well-structured software is easy to write and to debug, and provides a collection of modules that can be reused to reduce future programming costs. In this paper we show that two features of functional languages in particular, higher-order functions and lazy evaluation, can contribute significantly to modularity. As examples, we manipulate lists and trees, program several numerical algorithms, and implement the alpha-beta heuristic (an algorithm from Artificial Intelligence used in game-playing programs). We conclude that since modularity is the key to successful programming, functional programming oers important advantages for software development.
40448216
Multiple fault detection using single fault test sets
A simulation study of the 74LS181 4-b ALU (arithmetic logic unit) using 16 complete single stuck-at fault test sets demonstrated significantly higher multiple stuck-at fault coverage than predicted by previous theoretical studies. Analysis of the undetected multiple faults shows the effect of circuit and test set characteristics on fault coverage. A fault masking property, defined as self-masking, is observed for the undetected faults in the simulation study. A heuristic is described for evaluating the multiple fault coverage of single stuck-at fault test sets. A second heuristic generates augmented test sets, providing improved multiple stuck-at fault coverage with a minimal increase in test set development cost. >
14804186
Proving the correctness of reactive systems using sized types
We have designed and implemented a type-based analysis for proving some basic properties of reactive systems. The analysis manipulates rich type expressions that contain information about the sizes of recursively defined data structures. Sized types are useful for detecting deadlocks, nontermination, and other errors in embedded programs. To establish the soundness of the analysis we have developed an appropriate semantic model of sized types.