Edge-skeletons in arrangements with applications

An edge-skeleton in an arrangementA(H) of a finite set of planes inE ³ is a connected collection of edges inA(H). We give a method that constructs a skeleton inO(n logn) time per edge. This method implies new and more efficient algorithms for a number of structures in computational geometry including order-k power diagrams inE ² and space cutting trees inE ³.We also give a novel method for handling special cases which has the potential to substantially decrease the amount of effort needed to implement geometric algorithms.     

Flexible biomedical microdevices with double-sided electrode arrangements for neural applications

Micromachined devices with substrate-integrated electrodes are the key components in implantable microsystems for recording of neural signals or electrical stimulation of nerves. So far, electrodes have been located on only one side of the microsystems. In this paper, a technology has been developed to fabricate multichannel microelectrodes that are located on the top side and the back side of a flexible device. The process technology for polyimide-based devices is described. Prototypes of implantable microdevices with double-sided electrodes, called flexible nerve plates, have been fabricated. Results are discussed on scanning electron microscopy, cross-sections, and first electrochemical characterizations of the electrodes.     

A note on searching line arrangements and applications

We study the problem of searching for a vertex with a desired property in the arrangement of a set of lines in the plane. We show that this problem can be solved efficiently by modifying (and simplifying) two slope selection algorithms without using parametric search. We apply this result to a points approximation problem and obtain an optimal solution for it without using parametric search. Since this line arrangement searching problem is quite natural, our result may find other applications as well.     

Computing with planar toppling domino arrangements

A method for implementing Boolean logic functions using arrangements of toppling dominoes is described. Logic functions are implemented using only lines of dominoes and fork junctions. Using a dual-rail representation for Boolean values, any desired combinational function can be implemented. Circuits constructed using this method have no timing or order constraints on their inputs and require no out-of-plane bridges for passing one line of dominoes over another. Since they are built using toppling dominoes, circuits can be used only once.     

Parallel algorithms for arrangements

We give the first efficient parallel algorithms for solving the arrangement problem. We give a deterministic algorithm for the CREW PRAM which runs in nearly optimal bounds ofO (logn log^* n) time andn ²/logn processors. We generalize this to obtain anO (logn log^* n)-time algorithm usingn ^d /logn processors for solving the problem ind dimensions. We also give a randomized algorithm for the EREW PRAM that constructs an arrangement ofn lines on-line, in which each insertion is done in optimalO (logn) time usingn/logn processors. Our algorithms develop new parallel data structures and new methods for traversing an arrangement.This work was supported by the National Science Foundation, under Grants CCR-8657562 and CCR-8858799, NSF/DARPA under Grant CCR-8907960, and Digital Equipment Corporation. A preliminary version of this paper appeared at the Second Annual ACM Symposium on Parallel Algorithms and Architectures [3].     

Minimean optimal key arrangements in hash tables

For an open-addressing hash functionh and a setA ofn keys, letCh(A) be the expected retrieval cost when the keys are arranged to minimize the expected retrieval cost in a full table. It is shown that, asymptotically for largen, whenh satisfies a certain doubly dispersive property, as is the case for double hashing,C _h (A)=0(1) with probability 1 – 0(1) for a randomA.This research was supported in part by the National Science Foundation under Grant DCR-8308109.     

Preliminary arrangements of arguments in lazy evaluation

This paper describes a new implementation technique calledpreliminary arrangements of arguments for lazy functional languages. Unlike conventional lazy evaluators, the evaluator with preliminary arrangements partly processes every argument before calling functions. It works in a lazy way with less memory cells than conventional methods. The practical importance of this technique is demonstrated by some benchmark results.     

Organizational arrangements for MIS units

Decisions on organizational arrangements for MIS units comprise location in the organization, rank of responsible executive, organization of MIS implementators, degree of centralization, the user interface, the study group, the steering committee, the data base administrator, the corporate computer staff, and external assistance. Based on a wide-ranging survey of papers in the field of MIS, the authors have formulated guidelines which derive from the impact of organizational decisions on the success or failure or MIS and MIS projects.     

A numerical study of the Coriolis effect in centrifugal microfluidics with different channel arrangements

The Coriolis force has been of great interest to control the transversal flow that is critical for mixing or switching fluids in centrifugal microfluidics. Therefore, the variation in the Coriolis effect has been extensively investigated by varying the rotational speeds and the cross-sectional geometry of microchannels. However, the subject of such investigations has been limited to radially positioned microchannels even though channels can lie everywhere on the rotating platform with different arrangements. In this study, we use numerical methods to investigate the Coriolis effect resulting from the angular alignment (AA) and radial displacement (RD) of rotating microchannels. Our analysis focuses on determining the contribution that different channel arrangements have in the deviation of parabolic velocity profiles, which is generally produced by the effective Coriolis force. We found that the flow can deviate even at a low rotational speed, where the Coriolis force is negligible, with an AA of up to 33 % which is a sufficient amount for flow switching. Once the rotational speed reaches to the critical RPM, the flow deviates by an effective Coriolis force, but the deviation systematically varies with AA or RD. As the Coriolis force becomes more dominant with a high rotational speed, the deviation reaches a saturation point, while flow rate is regulated by AA or RD, enabling the flow rate to remain low even at very high RPM, without reducing the deviation. The variation in the Coriolis effect due to the different channel arrangements investigated in this study is believed to provide an essential basis to design and develop centrifugal microfluidic systems.     

Mining frequent arrangements of temporal intervals

The problem of discovering frequent arrangements of temporal intervals is studied. It is assumed that the database consists of sequences of events, where an event occurs during a time-interval. The goal is to mine temporal arrangements of event intervals that appear frequently in the database. The motivation of this work is the observation that in practice most events are not instantaneous but occur over a period of time and different events may occur concurrently. Thus, there are many practical applications that require mining such temporal correlations between intervals including the linguistic analysis of annotated data from American Sign Language as well as network and biological data. Three efficient methods to find frequent arrangements of temporal intervals are described; the first two are tree-based and use breadth and depth first search to mine the set of frequent arrangements, whereas the third one is prefix-based. The above methods apply efficient pruning techniques that include a set of constraints that add user-controlled focus into the mining process. Moreover, based on the extracted patterns a standard method for mining association rules is employed that applies different interestingness measures to evaluate the significance of the discovered patterns and rules. The performance of the proposed algorithms is evaluated and compared with other approaches on real (American Sign Language annotations and network data) and large synthetic datasets.     

On the paging-complexity of periodic arrangements

A simple model of a paging-system is investigated. The importance of the concept of pagination is stressed. The page-reference-strings under consideration stem from paginating simple loops, i.e. periodic sequences of consecutively accessed addresses. These reference strings are called periodic arrangements. The main objectives are: firstly, to prove a locality principle for this type of program structure: Given a pagination, generate as many references as possible to the same page in order to minimize page-traffic! Secondly, to show that this optimizing principle only holds for certain types of paging-algorithms, like Belady's algorithm and FIFO. It does no longer hold for the widely used paging-algorithm LRU, for instance.     

Parasitic motion comparison of 3-PRS parallel mechanism with different limb arrangements

The 3-PRS parallel mechanism (PM) is an important category of lower-mobility parallel mechanisms. Because it can undergo one translational degree of freedom (DOF) and two rotational DOFs, the 3-PRS PM has great potential in practical application and has received extensive attention. Parasitic motion occurring in the constrained DOFs of a 3-PRS PM is a key issue affecting its application. First, the 3-PRS PM is classified into seven subcategories based on the geometrical arrangements of limbs. Then, parasitic motion of each subcategory is discussed in detail and case studies are presented. It is illustrated that the complexity of parasitic motion of the 3-PRS PM is determined by the limb arrangement. The architecture of the 3-PRS PM without parasitic motion is also identified.     

Solving optimization problems with linear-fractional objective functions and additional constraints on arrangements

The paper proposes an exact method to solve an optimization problem on arrangements with a linear-fractional objective function and additional linear constraints. The efficiency of the solution algorithm is analyzed by means of numerical experiments. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 5, pp. 79–85, September–October 2006.     

A note on point location in arrangements of hyperplanes

We give an algorithm for point location in an arrangement of n hyperplanes in E^d with running time poly(d,logn) and space O(n^d). The space improves on the O(n^d+ε) bound of Meiser's algorithm [Inform. and Control 106 (1993) 286] that has a similar running time.     

Use-definition chains with applications

Methods of compile-time program analysis for automatic code optimization usually include control flow analysis, in which possible execution flow paths are modeled, and data flow analysis, in which data relatiohsips are modeled. One representation of data relations in a program, via use-definition chains, is examined in the light of a particular example problem—the global elimination of “useless” computation. Two elimination algorithms which use differently organized use-definition chains are presented and compared for space complexity on two pathologically different families of flow graphs. Algorithms to compute chains of both varieties are also developed.