|A Space-Economic Representation of Transitive Closures in Relational Databases|
A composite object represented as a directed graph (digraph for short) is an important data structure that requires efficient support in CAD/CAM, CASE, office systems, software management, web databases, and document databases. It is cumbersome to handle such objects in relational database systems when they involve ancestor-descendant relationships (or say, recursive relationships). In this paper, we present a new encoding method to label a digraph, which reduces the footprints of all previous strategies. This method is based on a tree labeling method and the concept of branchings that are used in graph theory for finding the shortest connection networks. A branching is a subgraph of a given digraph that is in fact a forest, but covers all the nodes of the graph. On the one hand, the proposed encoding scheme achieves the smallest space requirements among all previously published strategies for recognizing recursive relationships. On the other hand, it leads to a new algorithm for computing transitive closures for DAGs (directed acyclic graph) in O(eŞb) time and O(nŞb) space, where n represents the number of the nodes of a DAG, e the numbers of the edges, and b the DAGs breadth. In addition, this method can be extended to cyclic digraphs and is especially suitable for a relational environment.
A Systematic Methodology for Actuator Augmentation in the Supervisory Control of Discrete Event Systems
Vigyan Chandra, Siddhartha Bhattacharyya, Satya Mohanty
Supervisory control theory of discrete event systems in the Ramade-Wonham paradigm addresses the problem of restricting the system evolution so that it conforms to certain predefined behavior commonly referred to as specifications. This theory states that a sequence of events that cause the plant to violate the specifications is suitably pruned or eliminated. However, in doing so, event traces, partial prefixes of which that actually meet control specification are eliminated as well.
This happens for instance whenever a chain of uncontrollable event extensions render the plant behavior trajectory irrevocably outside the outlined specifications. Such partial conformance can be ensured if the capability of the system is augmented by additional actuators so that in the augmented plant there is a greater degree of control over uncontrollable events. It does not follow trivially where such actuators are to be placed. We propose an algorithm that enables us to identify states of the automaton where the new actuators need to be inserted, thus enlarging the scope of its applicability to system identification purposes as well.
Collaborative Tool and Its Applications
Taiyo MAEDA, Yoshimasa KADOOKA, Yoshio TAGO
The desk side laboratory (DSLab) which makes it possible for users who are in far places geographically to do research and development through internet on their web browsers, has been developed only using commodity products.@It has easy-to-use user interface. It has been shown that DSLab is useful for collaborative research of particle image velocimetry in fluid dynamics, collaborative system development, and e-Learning.@It is emphasized that, when used with digital equipment such as digital microscope, DSLab has a wide range of applications. It is expected that both of time and of travel cost needed in research and development are reduced largely.
Cybernetic Control in a Supply Chain: Wave Propagation and Resonance
Ken Dozier, David Chang
The cybernetic control and management of production can be improved by an understanding of the dynamics of the supply chains for the production organizations. This paper describes an attempt to better understand the dynamics of a linear supply chain through the application of the normal mode analysis technique of physics. A model is considered in which an organizations response to a perturbation from the steady state is affected by the inertia which the company naturally exhibits. This inertia determines how rapidly an organization can respond to deviations from the steady state of its own inventories and those of the two organizations immediately preceding and following it in the chain. The model equations describe the oscillatory phenomena of the naturally occurring normal modes in the chain, in which waves of deviations from the steady state situation travel forward and backwards through the chain. It would be expected that the most effective cybernetic control occurs when resonant interventions cause either amplification or damping of the deviations from the steady state.
Frequency Adaptive Control Technique for Periodic Runout and Wobble Cancellation in Optical Disk Drives
Yee-Pien Yang, Jieng-Jang Liu
Periodic disturbance occurs in various applications on the control of the rotational mechanical systems. For optical disk drives, the spirally shaped tracks are usually not perfectly circular and the assembly of the disk and spindle motor is unavoidably eccentric. The resulting periodic disturbance is, therefore, synchronous with the disk rotation, and becomes particularly noticeable for the track following and focusing servo system. This paper applies a novel adaptive controller, namely Frequency Adaptive Control Technique (FACT), for rejecting the periodic runout and wobble effects in the optical disk drive with dual actuators. The control objective is to attenuate adaptively the specific frequency contents of periodic disturbances without amplifying its rest harmonics. FACT is implemented in a plug-in manner and provides a suitable framework for periodic disturbance rejection in the cases where the fundamental frequencies of the disturbance are alterable. It is shown that the convergence property of parameters in the proposed adaptive algorithm is exponentially stable. It is applicable to both the spindle modes of constant linear velocity (CLV) and constant angular velocity (CAV) for various operation speeds. The experiments showed that the proposed FACT has successful improvement on the tracking and focusing performance of the CD-ROM, and is extended to various compact disk drives.
GENII-LIN: a Multipurpose Health Physics Code Built on GENII-1.485
Marco Sumini, Francesco Teodori
The aim of the GENII-LIN project was to develop an open source multipurpose health physics code running on Linux platform, for calculating radiation dose and risk from radionuclides released to the environment. The general features of the GENII-LIN system include
 capabilities for calculating radiation dose both for acute and chronic releases, with options for annual dose, committed dose and accumulated dose
 capabilities for evaluating exposure pathways including direct exposure via water (swimming, boating, fishing), soil (buried and surface sources) and air (semi-infinite cloud and finite cloud model), inhalation pathways and ingestion pathways.
The release scenarios considered are:
- acute release to air, from ground level or elevated sources, or to water;
- chronic release to air, from ground level or elevated sources, or to water;
- initial contamination of soil or surfaces.
Keywords: radiation protection, Linux, health physics, risk analysis.
Integrated Control Strategies Supporting Autonomous Functionalities in Mobile Robots
Brandon Sights, H.R. Everett, Estrellina Pacis, Greg Kogut, Michael Thompson
High-level intelligence allows a mobile robot to create and interpret complex world models, but without a precise control system, the accuracy of the world model and the robots ability to interact with its surroundings are greatly diminished. This problem is amplified when the environment is hostile, such as in a battlefield situation where an error in movement or a slow response may lead to destruction of the robot. As the presence of robots on the battlefield continues to escalate and the trend toward relieving the human of the low-level control burden advances, the ability to combine the functionalities of several critical control systems on a single platform becomes imperative.
|Issues in Component-Based Development: Towards Specification with ADLs|
Rafael González, Miguel Torres
Software development has been coupled with time and cost problems through history. This has motivated the search for flexible, trustworthy and time and cost-efficient development. In order to achieve this, software reuse appears fundamental and component-based development, the way towards reuse. This paper discusses the present state of component-based development and some of its critical issues for success, such as: the existence of adequate repositories, component integration within a software architecture and an adequate specification. This paper suggests ADLs (Architecture Description Languages) as a possible means for this specification.
Jupiter: Peer-to-Peer Networking Platform over Heterogeneous Networks
Norihiro Ishikawa, Takeshi Kato, Hiromitsu Sumino, Johan Hjelm, Shingo Murakami
Peer-to-peer has entered the public limelight over the last few years. Several research projects are underway on peer-to-peer technologies, but no definitive conclusion is currently available. Compared with traditional Internet technologies, peer-to-peer has the potential to realize highly scalable, extensible, and efficient distributed applications. This is because its basic functions realize resource discovery, resource sharing, and load balancing in a highly distributed manner. An easy prediction is the emergence of an environment in which many sensors, people, and many different kinds of objects exist, move, and communicate with one another. Peer-to-peer is one of the most important and suitable technologies for such networking since it supports discovery mechanisms, simple one-to-one communication between devices, free and extensible distribution of resources, and distributed search to handle the enormous number of resources. The purpose of this study is to explore a universal peer-to-peer network architecture that will allow various devices to communicate with one another across various networks. We have been designing architecture and protocols for realizing peer-to-peer networking among various devices. We are currently designing APIs that are available for various peer-to-peer applications and are implementing a prototype called Jupiter as a peer-to-peer networking platform over heterogeneous networks.
Off-Axis Gaussian Beams with Random Displacement in Atmospheric Turbulence
Yahya Baykal, Halil Eyyuboglu, Yusuf Yenice
Our recent work in which we study the propagation of the
general Hermite-sinusoidal-Gaussian laser beams in wireless
broadband access telecommunication systems is elaborated in
this paper to cover the special case of an off-axis Gaussian
beam. We mainly investigate the propagation characteristics in
atmospheric turbulence of an off-axis Gaussian beam
possessing Gaussian distributed random displacement
parameters. Our interest is to search for different types of laser
beams that will improve the performance of a wireless
broadband access system when atmospheric turbulence is
considered. Our formulation is based on the basic solution of
the second order mutual coherence function evaluated at the
receiver plane. For fixed turbulence strength, the coherence
length calculated at the receiver plane is found to decrease as
the variance of the random displacement is increased. It is
shown that as the turbulence becomes stronger, coherence
lengths due to off-axis Gaussian beams tend to approach the
same value, irrespective of the variance of the random
displacement. As expected, the beam spreading is found to be
pronounced for larger variance of displacement parameter.
Average intensity profiles when atmospheric turbulence is
present are plotted for different values of the variance of the
random displacement parameter of the off-axis Gaussian beam.
Privacy-Preserving Discovery of Multivariate Linear Relationship
Ningning Wu, Jing Zhang, Li Ning
The fast development of network and database techniques makes the data collecting and storing much easy and convenient. With more data being collected and available, there come the increasing requirements and huge opportunities for cooperative computation, where data are distributed across sites, and each site holds a portion of the data and wishes to collaborate to detect globally valid multivariate linear relationship.
This paper considers the privacy-preserving cooperative linear system of equations (PPC-LSE) problem in a large, heterogeneous, distributed database scenario, in which two parties would like to conduct cooperative computation from their private database while keeping their own data secret. The paper proposes a privacy-preserving algorithm to discover multivariate linear relationship based on factor analysis. Compared with other PPC_LSE algorithms, the proposed algorithm not only significantly reduces the communication cost, but also avoids the random
Recursion Of Binary Space As A Foundation Of Repeatable Programs
Every computation, including recursion, is based on natural philosophy. Our world may be expressed in terms of a binary logical space that contains functions that act simultaneously as objects and processes (operands and operators). This paper presents an outline of the results of research about that space and suggests routes for further inquiry. Binary logical space is generated sequentially from an origin in a standard coordinate system. At least one method exists to show that each of the resulting 16 functions repeats itself by repeatedly forward-feeding outputs of a function operating over two others as new operands of the original function until the original function appears as an output, thus behaving as an apparent homeostatic automaton. As any space of any dimension is composed of one or more of these functions, so the space is recursive, as well. Semantics gives meaning to recursive structures, computer programs and fundamental constituents of our universe being two examples. Such thoughts open inquiry into larger philosophical issues as free will and determinism.
Rogue AP Detection in the Wireless LAN for Large Scale Deployment
Sang-Eon Kim, Byung-Soo Chang, Sang Hong Lee, Dae Young Kim
The wireless LAN standard, also known as WiFi, has begun to use commercial purposes. This paper describes access network architecture of wireless LAN for large scale deployment to
provide public service. A metro Ethernet and digital subscriber line access network can be used for wireless LAN with access point. In this network architecture, access point plays interface between wireless node and network infrastructure. It is important to maintain access point without any failure and problems to public users. This paper proposes definition of
rogue access point and classifies based on functional problem to access the Internet. After that, rogue access point detection scheme is described based on classification over the wireless LAN. The rogue access point detector can greatly improve the network availability to network service provider of wireless LAN.
Collision Avoidance of Moving Obstacles for Underwater Robots
KWON KYOUNG YOUB, Cho Jeongmok, Kwon Sung-Ha, Joh Joongseon
A fuzzy logic for autonomous navigation of
underwater robot is proposed in this paper. The
VFF(Virtual Force Field) algorithm, which is widely used in the field of mobile robot, is modified for application to the autonomous navigation of underwater robot. This Modified Virtual Force Field(MVFF) algorithm using the
fuzzy logic can be used in either track keeping or obstacle avoidance. Fuzzy logics are devised to handle various situations which can be faced during autonomous navigation of underwater robot. A graphic simulator based on OpenGL for an autonomous navigation has been developed. The good performance of the proposed MVFF algorithm is verified through computer simulations on an underwater robot.