Feasible Architecture Research Articles

Petastar: a petabit photonic packet switch

This paper presents a new petabit photonic packet switch architecture, called PetaStar. Using a new multidimensional photonic multiplexing scheme that includes space, time, wavelength, and subcarrier domains, PetaStar is based on a three-stage Clos-network photonic switch fabric to provide scalable large-dimension switch interconnections with nanosecond reconfiguration speed. Packet buffering is implemented electronically at the input and output port controllers, allowing the central photonic switch fabric to transport high-speed optical signals without electrical-to-optical conversion. Optical time-division multiplexing technology further scales port speed beyond electronic speed up to 160 Gb/s to minimize the fiber connections. To solve output port contention and internal blocking in the three-stage Clos-network switch, we present a new matching scheme, called c-MAC, a concurrent matching algorithm for Clos-network switches. It is highly distributed such that the input-output matching and routing-path finding are concurrently performed by scheduling modules. One feasible architecture for the c-MAC scheme, where a crosspoint switch is used to provide the interconnections between the arbitration modules, is also proposed. With the c-MAC scheme, and an internal speedup of 1.5, PetaStar with a switch size of 6400 /spl times/ 6400 and total capacity of 1.024 petabit/s can be achieved at a throughput close to 100% under various traffic conditions.

Terminology Tools: State of the Art and Practical Lessons

As controlled medical terminologies evolve from simple code-name-hierarchy arrangements, into rich, knowledge-based ontologies of medical concepts, increased demands are placed on both the developers and users of the terminologies. In response, researchers have begun developing tools to address their needs. The aims of this article are to review previous work done to develop these tools and then to describe work done at Columbia University and New York Presbyterian Hospital (NYPH). Researchers working with the Systematized Nomenclature of Medicine (SNOMED), the Unified Medical Language System (UMLS), and NYPH's Medical Entities Dictionary (MED) have created a wide variety of terminology browsers, editors and servers to facilitate creation, maintenance and use of these terminologies. Although much work has been done, no generally available tools have yet emerged. Consensus on requirement for tool functions, especially terminology servers is emerging. Tools at NYPH have been used successfully to support the integration of clinical applications and the merger of health care institutions. Significant advancement has occurred over the past fifteen years in the development of sophisticated controlled terminologies and the tools to support them. The tool set at NYPH provides a case study to demonstrate one feasible architecture.

Architectures and Performance of Optical Packet Switching over WDM

Packet switching over wavelength division multiplexing (WDM) channels is considered with the aim to investigate algorithms for wavelength assignment and to define feasible switch architectures, in the presence of connectionless or connection-oriented transfer modes. In particular, as regards the connection-oriented scenario, mapping of virtual connections onto wavelengths operated by network nodes is considered and procedures are proposed to achieve statistical multiplexing efficiency by dynamic wavelength re-assignment. Switch architectures to support dynamic wavelength encoding and the related performance evaluation are presented and discussed in the paper, evidencing the benefits of packet switching over WDM.

Multihop wireless IEEE 802.11 LANs: A prototype implementation

In this paper, we present a prototype for a new architecture, MCN (Multihop Cellular Network) implemented over a wireless LAN platform. MCN preserves the virtue of traditional single-hop cellular networks where the service infrastructure is constructed by many BSs (Base Stations) but it also adds the flexibility of ad hoc networks where wireless transfer through mobile stations in multiple hops is allowed. MCN can reduce the number of required BSs or improve the throughput performance. In the prototype of MCN, a bridging protocol, BMBP (Base-driven Multihop Bridging Protocol) runs between mobile stations and access points to enable multihop routing and roaming. Demonstration show that MCN is a feasible architecture for wireless LANs.

Traffic control through in-service monitoring for QoS improvement in ATM networks

Asynchronous transfer mode (ATM) networks are expected to support multimedia communications with diverse traffic characteristics, these traffic are statistically multiplexed to efficiently utilize the network bandwidth. However, the high bandwidth utilization may deteriorate traffic-dependent quality of service (QoS). To accommodate QoS requirements while still maintaining high bandwidth utilization, it is necessary to prioritize user's service requirements through effective resource management. This article presents a traffic control approach through in-service monitoring, which employs dynamic buffer allocation to allow complete buffer sharing by all service classes as well as improves QoS of delay-sensitive traffic using the so-called Earliest Expected Due-time First scheduling. The simulation results demonstrate that diverse multimedia traffic achieves satisfactory performance using our scheme. A feasible implementation architecture is also addressed.

Expansion of an institutional quality control program at a comprehensive cancer center

The defect of process equipments is a major factor that impairs the yields in the mass production of semiconductor wafer fabrication and it is a main supervision means to use high-resolution defect inspection tools to detect and monitor the defect damage. Due to the high investment costs of these inspection tools and the resulting decrease in the throughput, how to improve the sampling rate is an important issue for the associated inspection strategy. This paper proposes a new concept and implementation of virtual inspection (VI) to enhance the detection and monitoring of defect in semiconductor production process. The underlying theory of the VI concept is that the state variables identifications (SVIDs) of process equipments can reflect the process quality effectively and loyally. The approach of VI is to combine the application of the fault detection and classification (FDC), and the defect library and the re-engineering of inspection procedure to reach the full-scope of strategic objective. VI enables the defect monitoring to enter a new era by promoting the monitoring level of defect inspection from the previous lot-sampling basis to the wafer-sampling level, and hence upgrades the sampling strategy from random-sampling to full and right-sampling. In this study, various typical defect cases are utilized to illustrate how to create VI models and verify the reliability of the proposed approach. Furthermore, a feasible architecture of the VI implementation for mass production in semiconductor factory is presented in the paper.

Design of pigment dispersants: Methodology for selection of anchoring groups

The development of pigment dispersants for waterborne or solvent-borne paint systems requires knowledge about anchoring groups, soluble tails, and about an effective and practically feasible architecture to build them together into one molecule.

Synchronous all‐optical code‐division multiple‐access networks

AbstractA feasible architecture is proposed for implementing synchronous all‐optical code‐division multiple‐access (CDMA) networks with full channel tunability. The proposed network uses fastly programmable all‐optical CDMA encoders and decoders which are based on tunable optical delay‐lines and require only a small number of electro‐optic switches. Coding and decoding algorithms for “synchronous” prime‐sequence codes that can be rapidly performed in the optical domain are described. Moreover, a two‐wavelength scheme is presented to effectively solve the problems associated with clock distribution and frame synchronization in large‐scale synchronous CDMA networks. By using the proposed technique, all‐optical CDMA transmitters and receivers can be constructed with integrated optics and can achieve a very high processing speed.

Optical Interconnectivity in a Scalable Data-Parallel System

Scalability. Few would disagree that the future of high-performance computing lies with massively parallel systems(MPS), since there are major physical limitations to the clockrate of a single processor. Massively parallel systems arerequired to be scalable in the sense that their performanceshould be proportional to the number of processors. However,a feasible architecture for a scalable massively parallel systemis still wanting, as true, i.e., unlimited scalability is not onlytheoretically impossible but even in the practical sense cannotbe achieved on a range of more than an order of magnitude inthe number of processors. Whatever a system’s architecture,interconnect, or programming model, something will not scale:the throughput or latency of the interconnect, its cost, orthe synchronization overheads. Since all these componentscontribute to performance in different ways, the issue of scal-ability is a very complex one indeed.So in what sense can one argue for scalability of massivelyparallel systems? There have been quite a few attempts todefine it (see [1]) on the basis of some strong assumptionsregarding the nature of parallel computation. The mostcommon assumption that is being made in such analyses is thatthe processors run some predominantly local processes whichrequire little external communication (it manifests itself in theparameter “communication to computation ratio” assumed tobe small and used in all but a few performance models). Bymigrating these self-contained processes and placing severalof them per processor to balance out computational workacross the system, it is believed that scalability may beachieved without requiring physically unfeasible networkingand/or dramatically different computational models. In reality,however, process concurrency of such kind continues to facevarious fundamental limitations from data mapping to dynamicload balancing to program paradigm issues.Data parallelism. We would like to address a simpler, andin our view more promising, way of doing parallel computing

A synchronization infrastructure for multicast multimedia at the presentation layer

In order to have computers successfully become consumer electronics products, an infrastructure of multicast multimedia networking presentation architecture that allows low-end computer, e.g., a set-top-box or a diskless networking PC, having isochronous multimedia presentations is urgently required. The paper describes a feasible multicast multimedia presentation network architecture and the corresponding presentation control mechanisms. The network architecture is based on a lower layer multicast communication network, e.g. MBONE, and provides the corresponding management of multicast multimedia presentations which include multimedia resource management, admission management, multicast communication management, and multimedia presentation management. Based on the proposed network architecture, we present the corresponding media transmission methods, presentation control schemes, and synchronization control schemes for multicast multimedia presentations in detail.

Improving optical character recognition accuracy using adaptive image restoration

A technique that can improve the optical character rec- ognition (OCR) accuracy of text images is presented. By using the output from an OCR system and a distorted text image, this tech- nique trains an adaptive restoration filter and then applies the filter to the distorted text that the OCR system could not recognize. The restored text image is then reprocessed by the OCR system, and the restored characters are recognized with a higher accuracy than the distorted text. A series of experiments were performed to deter- mine a feasible adaptive restoration filter architecture, to establish this technique's ability to restore uniformly distorted text, and to demonstrate this technique's ability to improve the OCR accuracy of real world text documents. The results of these experiments show that this technique can improve both pixel and OCR accuracy of distorted text images. © 1996 SPIE and IS&T.

Architecture design for regulating and scheduling user's traffic in ATM networks

The asynchronous transfer mode (ATM) technique provides a standardized and flexible scheme to transport and switch traffic effectively for different services. To provide satisfactory quality of service (QOS) to all users on the network, it is necessary to control the user's traffic so that network resources can be efficiently and fairly utilized by all the users while still meeting the individual QOS requirement. In this paper, we propose to control the user's traffic at two places in the network: at the user-network interface (UNI) by a traffic shaper or a traffic enforcer, and at the network-node interface (NNI) by a traffic regulator and a traffic scheduler. The traffic shaper/enforcer adopted in our work contains a buffer to delay and shape the violating cells that do not comply with some agreed-upon traffic parameters. The traffic regulator regulates cells at each network node to avoid long bursts being formed which may increase the network congestion probability. A traffic scheduler that follows the traffic regulator schedules the cells' departure sequences based on their delay priorites. We have proposed a general, feasible architecture to implement the traffic shaper, regulator, and scheduler, at various places in the network. A key component, the Sequencer chip, which contains 150k CMOS transistors, has been implemented to realize the architecture.

Systems for unified life-cycle mechanical engineering design: Shared-Tool architectures versus distributed tool architectures

A unified life-cycle engineering design (ULCED) system embodying conceptual design, detailed design, redesign, design for manufacturing, and design maintainability forms the basis of a new computer-based design discipline for improving the overall quality of manufactured goods. The objective of such a system is to review, evaluate, and analyze the entire life cycle of a product and to incorporate, in an integrated fashion, life-cycle knowledge within the design process. Individual CAD/CAM/CAE software, developed under various programming environments and operating systems, and on various types of computer hardware, have met with only limited success in achieving total computational integration. At the initial stages of development of such a system exploration of both technologically and economically feasible architectures is of critical importance.

An architecture for hybrid coding of NTSC TV signals

A hardware feasible architecture for DCT/DPCM hybrid coding of color television (TV) signals has been developed. The coding system is based on formatting four horizontal scan lines into blocks of the same subcarrier phase elements. The samples in each block are rearranged and transformed by a FDCT processor. Based on its average energy, a given transform block is compared with its adjacent blocks and the nearest block is selected as its estimate. The difference between the actual and the estimated values of the (DCT) coefficients are then quantized and encoded using nonuniform quantizers and a variable length coder. Furthermore, the maximum number of different wordlengths is assumed to be five. Therefore, five sets of 256-byte encoding ROMs are used to store the quantization tables. To reduce the redundancy in the code words, an adaptive coding scheme is used. The coding scheme is based on setting two threshold levels.