Socket Buffer Auto-Sizing for High-Performance Data Transfers

It is often claimed that TCP is not a suitable transport protocol for data intensive Grid applications in high-performance networks. We argue that this is not necessarily the case. Without changing the TCP protocol, congestion control, or implementation, we show that an appropriately tuned TCP bulk transfer can saturate the available bandwidth of a network path. The proposed technique, called SOBAS, is based on automatic socket buffer sizing at the application layer. In non-congested paths, SOBAS limits the socket buffer size based on direct measurements of the received throughput and of the corresponding round-trip time. The key idea is that the send window should be limited, after the transfer has saturated the available bandwidth in the path, so that the transfer does not cause buffer overflows (self-induced losses). A difference with other socket buffer sizing schemes is that SOBAS does not require prior knowledge of the path characteristics, and it can be performed while the transfer is in progress. Experimental results in several high bandwidth-delay product paths show that SOBAS provides consistently a significant throughput increase (20% to 80%) compared to TCP transfers that use the maximum possible socket buffer size. We expect that SOBAS will be mostly useful for applications such as GridFTP in non-congested wide-area networks.     

经济型19"机柜系统的选择

在"911"之后的经济环境条件下,设计工程师和系统集成者们在搭建一个经济型19"机柜系统时,总是要面对一个棘手的任务--如何找出蕴涵的价值.     

Utilization of industrial waste products as adsorbents for the removal of dyes

A number of low cost adsorbents from steel and fertilizer industries wastes have been prepared and investigated for the removal of anionic dyes such as ethyl orange, metanil yellow and acid blue 113 from aqueous solutions. The results indicate that inorganic wastes, i.e. blast furnace dust, sludge and slag from steel plants are not suitable for the removal of organic materials, whereas a carbonaceous adsorbent prepared from carbon slurry of fertilizer industry was found to adsorb 198, 211 and 219mg/g of ethyl orange, metanil yellow and acid blue 113, respectively. The adsorption of dyes on this adsorbent was studied as a function of contact time, concentration, particle size and temperature by batch method. The adsorption isotherm conformed to Langmuir model and the adsorption was found to be exothermic and physical in nature. Kinetic data conforms to Lagergren's equation with good correlation coefficients varying from 0.9998 to 0.9999 indicating that the adsorption is a first-order process. The adsorption data on carbonaceous adsorbent was compared to a standard activated charcoal sample and it was found that the prepared adsorbent is about 80% as efficient as standard activated charcoal and therefore, can be used as low cost alternative ( approximately 100 US dollars per ton) for colour removal from effluents.     

Synthesis and characterization of catalysts produced from paper mill sludge. I. Determination Of NOx removal capability

Characteristics and catalytic properties of a series of carbon-based catalysts (CBCs) produced from paper mill sludge were evaluated. The major processes involved in the production of the catalysts were chemical activation, impregnation, pyrolysis, and post pyrolysis rinsing. The porous structure, catalytic activity and thermostability of the catalysts were tailored during the production stage by introducing hetero-atoms (zinc chloride, and ferric nitrate) in the carbon structure. Characterization of the produced CBCs included determination of the surface area, pore size, and pore size distribution (PSD) from standard N₂-adsorption isotherm data. The extent of graphitization and the presence of metal crystals were identified from X-ray diffraction (XRD). The limit of the catalyst gasification was estimated from thermogravimetric analysis (TGA) conducted in an oxidized environment. The NO_x reduction capability of the produced catalysts was evaluated in the presence of carbon monoxide using a fixed bed reactor. The reaction temperature ranged from 300 to 500°C. It was shown that paper mill sludge is an excellent precursor for the production of CBCs with NO_x removal capability of 66–94%. The catalytic capability of the produced CBCs varied according to the method of production, catalyst surface properties (surface area, pore structure, PSD), metal composition and reaction temperature. The highest NO_x removal capacity was observed for the catalytic reactions carried out at 400°C. The mesoporous catalyst produced with a Zn:Fe molar ratio of 1:0.5 exhibited the maximum NO_x removal catalytic activity of 94%.     

Multiuser-based shadow watermark extraction system

A new watermarking scheme having the ability of sharing secret with multi-users is proposed. It splits the original watermark into two shares and embeds one share into the cover image to increase the security. A polarization procedure is performed to establish a polarity stream from the cover image. The second share and the polarity stream are used to generate a master key and several normal keys. In this system, only the super-user can reveal the genuine watermark directly. Other users possess the normal keys can obtain shadow watermarks merely. By combining the shadow watermarks together, the real watermark can be recovered.     

Shallow Trench Isolation for the 45-nm CMOS Node and Geometry Dependence of STI Stress on CMOS Device Performance

In the present work, a high aspect ratio process (HARP) using a new O₃/TEOS based sub atmospheric chemical vapor deposition process was implemented as STI gapfill in sub-65-nm CMOS. Good gapfill performance up to aspect ratios greater than 10:1 was demonstrated. Since the HARP process does not attack the STI liner as compared to HDP, a variety of different STI liners can be implemented. By comparing HARP with HDP, the geometry dependence of nand p-FET performance due to STI stress is discussed     

A novel methodology to measure the responsiveness of RMTs in reconfigurable manufacturing system

Reconfigurable manufacturing systems are designed to deliver exact functionality and capacity that is needed, when it is needed. The reconfigurable machine tool (RMT) plays a pivotal role in the accomplishment of this objective through their built in modular structure consisting of basic and auxiliary modules along with the open architecture software.     

Indigenous design and development of a micro-pulse lidar for atmospheric studies

A sophisticated micro-pulse lidar (MPL) has been designed and developed for the study of the atmospheric boundary layer (ABL) and clouds. The developed MPL uses a low energy pico-second pulsed Nd:YAG laser at 532 nm. The conventional receiver optic is used along with a photomultiplier tube in single photon detection mode. Stanford Research Systems' multi-channel scalar (MCS) is used with a personal computer for data acquisition. Due to the short laser pulse and a fast MCS, a spatial resolution of 0.75 m has been achieved. The control circuit has been designed to sense telescope cover status (open or closed) to avoid any mistakes in dark count and background data acquisition. The complete control software and Graphical User Interface (GUI) has been developed in Visual Basic. The lidar system has been tested both for its functionality to detect the variation in ABL and cloud height and also for its capability to acquire continuous night-time data without user interaction. In this article the design details and some preliminary results are discussed.     

Tropospheric ozone variability over the Indian coastline and adjacent land and sea

A tropospheric ozone variability study is carried out to investigate the spatial and temporal distribution over the coastline of the Indian peninsula and adjacent land and sea using NASA Langley Tropospheric Ozone Residual data set for the period 1979–2005. A strong seasonal cycle has been observed with large variation (～ 55%) over the upper eastern coast, followed by the upper and lower western coast, compared to the lower eastern coast (～ 33%). A negative gradient in ozone concentration is observed along eastern and western coasts during summer (slope ～ –0.78 and –0.65) and a positive gradient (slope ～ 0.16 and 0.21) during winter. The same is observed over the adjacent land and sea along the coastline with slight variation. This change in gradient can be attributed to the anthropogenic emission of precursor gases that reinforce localized photochemical production of ozone. In addition, topography, transport, seasonality of emission of precursor gases and the solar insolation cycle play a vital role.     

Determination of land surface temperature and its lapse rate in the Satluj River basin using NOAA data

Temperature lapse rate (TLR), an essential parameter for snowmelt runoff analysis, was determined for the Satluj River basin in the Western Himalayas. National Oceanic and Atmospheric Administration/Advanced Very High Resolution Radiometer (NOAA/AVHRR) data sets were used to determine the land surface temperature (LST) of the region using the split‐window algorithm proposed by Coll and Caselles (Journal of Geophysical Research, 1997, 102, pp. 16697–16713). The LST was correlated with the elevation values obtained from a US Geological Survey digital elevation model (USGS‐DEM) of the same area and the trend showed an inverse relationship between LST and elevation. The TLRs for the study area on 2 February, 1 March, 26 March, 16 October, 1 November and 20 November 2004 were in the range 0.6–0.74°C/100 m. The results obtained were compared with lapse rates determined using Moderate Resolution Imaging Spectroradiometer (MODIS) LST maps. TLR determination in the past was based on air temperature data available from meteorological stations that are sparsely located in rugged terrain such as the Himalayas. As these measurements were point data and had been measured manually, they may have led to erroneous results. Satellite data, however, provide continuous and potentially unbiased recording provided an accurate radiometric calibration and atmospheric correction can be achieved. A previous TLR calculation using air temperature from meteorological stations for the western Himalayan region was found to be 0.65°C/100 m. Air temperature and LST from NOAA‐AVHRR and MODIS‐Terra data were found to be in good agreement. This type of study will be useful for snowmelt runoff modelling studies for the Himalayan region.