On the design of a high-performance adaptive router for CC-NUMA multiprocessors

Copyright © 2003 IEEEThis work presents the design and evaluation of an adaptive packet router aimed at supporting CC-NUMA traffic. We exploit a simple and efficient packet injection mechanism to avoid deadlock, which leads to a fully adaptive routing by employing only three virtual channels. In addition, we selectively use output buffers for implementing the most utilized virtual paths in order to reduce head-of-line blocking. The careful implementation of these features has resulted in a good trade off between network performance and hardware cost. The outcome of this research is a High-Performance Adaptive Router (HPAR), which adequately balances the needs of parallel applications: minimal network latency at low loads and high throughput at heavy loads. The paper includes an evaluation process in which HPAR is compared with other adaptive routers using FIFO input buffering, with or without additional virtual channels to reduce head-of-line blocking. This evaluation contemplates both the VLSI costs of each router and their performance under synthetic and real application workloads. To make the comparison fair, all the routers use the same efficient deadlock avoidance mechanism. In all the experiments, HPAR exhibited the best response among all the routers tested. The throughput gains ranged from 10 percent to 40 percent in respect to its most direct rival, which employs more hardware resources. Other results shown that HPAR achieves up to 83 percent of its theoretical maximum throughput under random traffic and up to 70 percent when running real applications. Moreover, the observed packet latencies were comparable to those exhibited by simpler routers. Therefore, HPAR can be considered as a suitable candidate to implement packet interchange in next generations of CC-NUMA multiprocessors.Valentín Puente, José-Ángel Gregorio, Ramón Beivide, and Cruz Iz

Distance-hereditary embeddings of circulant graphs

©2003 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.In this paper we present a distance-hereditary decomposition of optimal chordal rings of 2k2 nodes into a set of rings of 2k nodes, where k is the diameter. All the rings belonging to this set have the same length and their diameter corresponds to the diameter of the chordal ring in which they are embedded. The members of this embedded set of rings are non-disjoint and preserve the minimal routing of the original circulant graph. Besides its practical consequences, our research allows the presentation of these optimal circulant graphs as a particular evolution of the traditional ring topology.Carmen Martinez, Beivide Beivide, Jaime Gutierrez, [Maria] Cruz Iz

An Assessment of Vegetation Variables in the Reclamation Area of the Ex-gold Mining at Ratatotok, Southeast Minahasa

The reclamation area of the ex gold-mining PT. Newmont Minahasa Raya (PT. NMR) will be used as a botanic gardens. This study aims to assess the reclamation program\u27s success based on a variable vegetation of the ex gold-mining area of PT. NMR for the basis of the next management. Observations of vegetation on each unit of area was done by nested sampling system, where plots were placed along a perpendicular transect in a contour line. Vegetation variables were recorded among other: species name, individual number, plot numbers, coordinates, temperature, humidity, canopy cover, and land cover. The effect of vegetation on both of two variable regions, revegetation area and non-revegetation area, was tested using discriminant analysis. The results showed that the vegetation composition of the ex gold mining area of PT. NMR was still dominated by introduction species i.e. gamal (Gliricidia sepium), mahoni (Swietenia macrophylla), and lamtoro (Leucaena leucocephala). The diversity of understorey vegetation was middle category. The vegetation structure of the revegetation area was still in its infancy and has not yet reached climax conditions. However, revegetation efforts PT. NMR has succeeded in restoring the composition and structure of vegetation resembling to vegetation conditions in secondary forests. For supporting the ecosystem stability and promoting development programs of botanic gardens, were the enrichment of native vegetation and endangered species is needed

The case of chaotic routing revisited

This paper presents a new evaluation of the Chaos router, a cut-through non-minimal adaptive router, which was reported to reach 95% of its theoretical throughput limit, at the time where most router proposals only reached 60 to 80%. We will revisit the Chaos router design, provide a new vision of its strengths and relate them to the state-of-the-art in adaptive router design. In particular, our analysis has identified a parameter of the router design that was not emphasized in the network evaluation presented by their authors, but that is the key to its outstanding performance. This parameter is the channel operation mode. By using the links in half-duplex mode, it allows adjacent network nodes to allocate their bandwidth to one or the other direction in response to the traffic needs. This channel operation mode reduces base latency and increases network throughput compared to full duplex mode for most synthetic traffic patterns.Cruz Izu, Ramon Beivide and Jose Angel Gregori

Desain Vegetasi Bernilai Konservasi Dan Ekonomi Pada Kawasan Penyangga Sistem Tata Air DAS Bolango (Designing of Vegetation Which Conservation and Economic Values in the Buffer Area of Water System at the Bolango Watershed)

Perencanaan pembangunan arboretum di DAS Bolango dengan konsep konservasi dan ekonomi perlu dilakukan karena DAS ini memiliki peranan yang penting dalam kehidupan masyarakat sekitar. Tujuan penelitian ini adalah memberikan rekomendasi tentang komposisi dan struktur vegetasi penyusun hutan pada kawasan arboretum sebagai pemelihara mata air Sungai Bolango. Penelitian dimulai dengan mengidentifikasi sumber mata air, tanah, dan kondisi vegetasi eksisting. Metode wawancara kepada masyarakat setempat dilakukan untuk mendukung data etnobotani. Kajian lahan dilakukan antara lain tata guna, kelas kemampuan, konsep pengelolaan, kesesuaian lahan, dan penentuan vegetasinya. Hasil identifikasi sumber mata air menunjukkan bahwa terdapat 3 lokasi yang potensial dibangun arboretum, yaitu Desa Meranti Kecamatan Tapa Kabupaten Bone Bolango, Desa Dulamayo Selatan Kecamatan Telaga Kabupaten Gorontalo, dan Desa Mongiilo Kecamatan Bolango Ulu Kabupaten Bone Bolango. Berdasarkan data kualitas tanah, ketiga lokasi memiliki media perakaran yang cukup baik untuk tanaman budi daya. Secara umum, semua jenis tanaman budi daya sesuai untuk ditanam di ketiga lokasi arboretum. Perlu dilakukan pembuatan teras dan penerapan pola tanam konservasi yang mengaplikasikan tanaman penutup tanah (cover crop), tanaman budi daya, dan pohon penyusun hutan. Selain itu, perlu pemberian pupuk organik berupa kompos dan pupuk kandang

Program Comprehension: Identifying Learning Trajectories for Novice Programmers

This working group asserts that Program Comprehension (PC) plays a critical part in the writing process. For example, this abstract is written from a basic draft that we have edited and revised until it clearly presents our idea. Similarly, a program is written in an incremental manner, with each step being tested, debugged and extended until the program achieves its goal. Novice programmers should develop their program comprehen- sion as they learn to code, so that they are able to read and reason about code while they are writing it. To foster such competencies our group has identified two main goals: (1) to collect and define learning activities that explicitly cover key components of program comprehension and (2) to define possible learning trajectories that will guide teachers using those learning activities in their CS0/CS1 or K-12 courses. [...

Preparation of Microcrystalline Silicon Based Solar Cells at High i-layer Deposition Rates Using a Gas Jet Technique

ABSTRACT A Gas Jet technique has been used to prepare microcrystalline silicon (µc-Si) thin films at deposition rates as high as 20 Å/s. The films have microcrystal sizes between 80 and 120 Å with a heterogeneous microstructure containing regions with columnar growth and other regions with a more randomly oriented microstructure. These materials have been used as i-layers for nip single-junction solar cells. The high deposition rates allow for fabrication of the required thicker µc-S

On the Selection of Pairing-Friendly Groups

We propose a simple algorithm to select group generators suitable for pairing-based cryptosystems. The selected parameters are shown to favor implementations of the Tate pairing that are at once conceptually simple and efficient, with an observed performance about 2 to 10 times better than previously reported implementations, depending on the embedding degree. Our algorithm has beneficial side effects: various non-pairing operations become faster, and bandwidth may be saved

Detection of Multi-TeV Gamma Rays from Markarian 501 during an Unforeseen Flaring State in 1997 with the Tibet Air Shower Array

In 1997, the BL Lac Object Mrk 501 entered a very active phase and was the brightest source in the sky at TeV energies, showing strong and frequent flaring. Using the data obtained with a high density air shower array that has been operating successfully at Yangbajing in Tibet since 1996, we searched for gamma-ray signals from this source during the period from February through August in 1997. Our observation detected multi-TeV $\gamma$-ray signals at the 3.7-Sigma level during this period. The most rapid increase of the excess counts was observed between April 7 and June 16 and the statistical significance of the excess counts in this period was 4.7-Sigma. Among several observations of flaring TeV gamma-rays from Mrk 501 in 1997, this is the only observation using a conventional air shower array. We present the energy spectrum of gamma-rays which will be worthy to compare with those obtained by imaging atmospheric Cerenkov telescopes.Comment: 9 pages, 7 figures, To appear in Ap

Primary proton spectrum between 200 TeV and 1000 TeV observed with the Tibet burst detector and air shower array

Since 1996, a hybrid experiment consisting of the emulsion chamber and burst detector array and the Tibet-II air-shower array has been operated at Yangbajing (4300 m above sea level, 606 g/cm^2) in Tibet. This experiment can detect air-shower cores, called as burst events, accompanied by air showers in excess of about 100 TeV. We observed about 4300 burst events accompanied by air showers during 690 days of operation and selected 820 proton-induced events with its primary energy above 200 TeV using a neural network method. Using this data set, we obtained the energy spectrum of primary protons in the energy range from 200 to 1000 TeV. The differential energy spectrum obtained in this energy region can be fitted by a power law with the index of -2.97 $\pm$ 0.06, which is steeper than that obtained by direct measurements at lower energies. We also obtained the energy spectrum of helium nuclei at particle energies around 1000 TeV.Comment: 25 pages, 22 figures, Accepted for publication in Phys. Rev.