22724577
Performance characterization of forwarding strategies in personal communication networks
The paper presents a framework for modeling and evaluating the performance of forwarding strategies in a personal communication services (PCS) mobile network. A forwarding strategy in the PCS network can be implemented by two mechanisms: a forwarding operation which follows a chain of databases to locate a mobile user, and a resetting operation which updates the databases in the chain so that the current location of a mobile user can be known directly without having to follow a chain of databases. We consider the PCS network as a server whose function is to provide services to the mobile user for "updating the location of the user as the user moves across a database boundary" and "locating the mobile user". We use a Markov chain to describe the behavior of the mobile user and analyze the best time when forwarding and resetting should be performed in order to optimize the service rate of the PCS network. We demonstrate the applicability of our approach with hexagonal coverage models for the PCS network and provide a physical interpretation of the result.
34408109
Modeling GIS Data Using OMEGA
31930663
Minimization of resource consumption for multidatabase query optimization
Due to the autonomy of individual databases, a multidatabase system (MDBS) has no control over the task execution within each database system. This complicates the issue of query optimization in a MDBS. Past researchers tackled this problem mainly by regenerating the cost model of each participating database systems. However a completely autonomous participating database system does nor own the information (data) as well as the mechanism (software) for converting data of one database to another to resolve the data type conflict problems that can occur in any MDBS environment. In addition, unpredictable factors that can drastically deviate the accuracy of a regenerated cost model (in the past research) come into play at unknown time. This confines the processing of an intersite operation (such as a join over two relations of different databases) to the MDBS only. The participating database systems will not be able to share the workload of the MDBS under this circumstance. Hence, minimizing the consumption of system resources of the MDBS is an urgent problem. The authors propose three scheduling algorithms that are used in the MDBS to reduce the processing cost of a multidatabase query. A major difference between the strategies and the past methods is that ours do not require the knowledge of the cost models of the participating databases.
2862791
A data delivery strategy in ubiquitous computing systems
Browsing Web pages through wireless devices will become more and more popular in the near future. However, accessing a large chunk of Web data incurs a great amount of access latency while a mobile user migrates across cells. This paper investigates this problem and proposes an effective way of delivering such data to a mobile user in a ubiquitous computing system. Our data delivery (/spl Dscr//sup 2/) strategy is based on the dynamic programming skill needed to pre-assign the user-requested data on the possible cells to be visited in order to reduce the access latency. We first design an encoding method for the cells and then derive the properties of the encoding scheme. These properties are then used in our algorithm to deliver the data. Finally, experiments are conducted to demonstrate the feasibility and efficiency of the proposed method.
18796888
Design and Performance Evaluation of Broadcast Algorithms for Time-Constrained Data Retrieval
We refer "time-constrained services" to those requests that have to be replied to within a certain client-expected time duration. If the answer cannot reach the client within this expected time, the value of the information may seriously degrade or even become useless. On-demand channels may not be able to handle all time-constrained services without degrading the performance. How to handle these services in broadcast channels becomes crucial to balance the load of wireless systems. In this paper, we study this problem and find the minimum number of broadcast channels required for such a task. Also, we propose solutions for this problem when the available channels are insufficient. Our performance result reveals that only a moderate number of channels is required to promote these time-constrained services
20308502
Object signatures for supporting efficient navigation in object-oriented databases
Most methods that have been proposed to improve query processing in object-oriented databases are designed for the aggregation hierarchy. Although the structure of the generalization hierarchy is similar to the aggregation hierarchy, techniques developed for the aggregation hierarchy cannot fully use the characteristics of the generalization hierarchy to improve performance. We devise a new object signature for the generalization hierarchy. The object signature consists of two parts: a reference signature and a structure signature. The former can be used to eliminate objects that do not match the nested predicates specified in the query, and the latter can be used to eliminate objects that do not belong to the target classes. We propose some processing methods using the object signatures for queries that involve generalization hierarchies. In addition, we define cost models of the object signature and then compare the performance of the traditional query processing method with the object signature method. The results show that using the object signatures can effectively reduce the number of disk accesses in a query.
2177844
Design, performance analysis, and implementation of a super-scalar video-on-demand system
Despite the availability of video-on-demand (VoD) services in a number of cities around the world, large-scale deployment of VoD services in a metropolitan area is still economically impractical. This study presents a novel super-scalar architecture for building very large-scale and efficient VoD systems. The proposed architecture combines the use of static multicast, dynamic multicast, and intelligent client-side caching to vastly reduce server and network resource requirement. Moreover, in sharp contrast to conventional VoD systems where the system cost increases at least linearly with the system scale, the proposed architecture becomes more efficient as the system scales up and can ultimately be scaled up to serve any number of users while still keeping the startup latency short. This paper presents this new architecture, proposes methods to support interactive playback controls without the need for additional server or client resources, and derives an approximate performance model to relate the startup latency with other system parameters. The performance model is validated using simulation and the architecture is evaluated under various system settings. Lastly, a system implementation is presented and benchmarking results obtained to further verify the architecture, the performance model, and the simulation results.
2648996
Determination of the Registration Point for Location Update by Dynamic Programming in PCS
Location management is important to effectively keep track of mobile terminals with reduced signal flows and database queries. Even though dynamic location management strategies are known to show good performance, we in this paper consider the static location management strategy which is easy to implement. A system with single home location register and pointer forwarding is assumed. A mobile terminal is assumed to have memory to store the IDs of visitor location registers (VLRs) each of which has the forwarding pointer to identify its current location. To obtain the registration point which minimizes the database access and signaling cost from the current time to the time of power-off probabilistic dynamic programming formulation is presented. A Selective Pointer Forwarding scheme is proposed which is based on one-step dynamic programming. The proposed location update scheme determines the least cost temporary VLR which point forwards the latest location of the mobile. The computational results show that the proposed scheme outperforms IS-41, pure Pointer Forwarding, and One-step Pointer Forwarding at the expense of small storage and a few computations at the mobile terminals.
7430073
P.L.-Spheres, convex polytopes, and stress
We describe here the notion of generalized stress on simplicial complexes, which serves several purposes: it establishes a link between two proofs of the Lower Bound Theorem for simplicial convex polytopes; elucidates some connections between the algebraic tools and the geometric properties of polytopes; leads to an associated natural generalization of infinitesimal motions; behaves well with respect to bistellar operations in the same way that the face ring of a simplicial complex coordinates well with shelling operations, giving rise to a new proof that p.l.-spheres are Cohen-Macaulay; and is dual to the notion of McMullen's weights on simple polytopes which he used to give a simpler, more geometric proof of theg-theorem.
205046494
Run-time support For parallel functional programming on shared-memory multiprocessors
Abstract The use of functional languages for parallel computing has been proposed for many years. Many functional languages were developed along with the design of new architectures such as data flow and reduction machines. In this article, we present a general model of a run-time system for a parallel functional language called SISAL, to be executed on shared-memory multiprocessors. The implementation of this run-time system is examined on two radically different architectures: a 32-way (symmetrical) VAX Research Multiprocessor M31 and a 4-way Cray X-MP system. To properly evaluate the effectiveness of SISAL on shared-memory multiprocessors, we suggest further research explore an interactive visual control mechanism that dynamically shows run-time behavior.
203663688
Practical Solutions for QoS-Based Resource Allocation
An apparatus and method is disclosed for forming a liquid-tight container having a rectangular cross-section formed from a one-piece, T-shaped blank of paperboard material. The carton preferably includes an access flap and straw element on one side thereof which, when manually lifted, exposes an end of the straw element from which the contents of the carton may be consumed by a user. The apparatus is compact in nature, possessing relatively few transport mechanisms which advance the T-shaped carton blank through a plurality of work stations. A novel method and apparatus for serially applying the straw element and access panel to the carton blank is disclosed, wherein the straw element and a length of polyethylene coated Mylar tape is automatically bonded to the carton blank upon a rotating heat sealing and alignment drum. A conveyor for collating a plural number of the carton blanks about a forming mandrel is also provided, and is positioned transversely to the remainder of the apparatus thereby significantly reducing the overall size of the apparatus. An ultrasonic welder bonds the side seams and end closure panels of the container upon a rotating crossbar mandrel which eliminates any misalignment during the sealing process. A substantially rigid conveyor transport carries a plurality of the carton blanks through pre-form, filler, and end closure work stations, and includes plural anvils for the ultrasonic welding process. An ejector mechanism is additionally provided which ejects the filled carton blanks from the rigid conveyor along a dual direction path, thereby eliminating the possibility of creasing or puncturing the filled and sealed container. The apparatus of the present invention additionally accommodates the production of differing size containers with only minor adjustments.