On multistage interconnection networks with small clock cycles

In packet switching using multistage interconnection networks (MIN's), it is generally assumed that the packet movements successively propagate from the last stage to the first stage in one network cycle. Ding and Bhuyan (1994), however, have shown that the network performance can be significantly improved if the packet movements are confined within each pair of adjacent stages using small clock cycles. In this short note, we present a model for estimating the performance of multibuffered MIN's employing the approach. Using the model, the relative effectiveness of the approach is identified compared to the traditional design     

A study on the machining of compressor rotors using formed tools

In this paper it was suggested the machining method that can improve machining accuracy and reduce the machining time applying the formed tools based on the rotor shape feature to finishing machining for efficient machining of asymmetric rotors. For machining the complicated asymmetric rotor profile, machining area is divided and formed tools are manufactured based on the rotor feature., and the efficient machining method of screw motor was proposed using the formed tools and four axis machining devices. With the suggested machining method, machining time could be reduced compared to the general end mill machining method, and the machining errors of the proposed method could be within the allowable tolerance of the product so as to carry out the precise machining.     

Interference Mitigation Using Uplink Power Control for Two-Tier Femtocell Networks

This paper proposes two interference mitigation strategies that adjust the maximum transmit power of femtocell users to suppress the cross-tier interference at a macrocell base station (BS). The open-loop and the closed-loop control suppress the cross-tier interference less than a fixed threshold and an adaptive threshold based on the noise and interference (NI) level at the macrocell BS, respectively. Simulation results show that both schemes effectively compensate the uplink throughput degradation of the macrocell BS due to the cross-tier interference and that the closed-loop control provides better femtocell throughput than the open-loop control at a minimal cost of macrocell throughput.     

Fabrication of Ordered Nanostructured Arrays Using Poly(dimethylsiloxane) Replica Molds Based on Three‐Dimensional Colloidal Crystals

Hexagonally arrayed structures of colloidal crystals with uniform surface are a good candidate for master molds to be used in soft lithography. Here, the fabrication of periodically arrayed nanostructures using poly(dimethylsiloxane) (PDMS) molds based on three‐dimensionally (3D) ordered colloidal crystals is reported. A robust, high‐quality 3D colloidal‐crystal master molds is prepared using the colloidal suspension containing a water‐soluble polymer. The surface patterns of the 3D colloidal crystals can then be transferred onto a polymer film via soft lithography, by means of the replication of the surface pattern with PDMS. Various hexagonally arrayed nanostructure patterns can be fabricated, including close‐packed and non‐close‐packed 2D arrays and honeycomb structures by the structural modification of the 3D colloidal‐crystal templates. The replicated hexagonally arrayed structures can also be used as templates for producing colloidal crystals with 2D superlattices.     

Load balancing and its performance evaluation for layer 3 and IEEE 802.21 frameworks in PMIPv6‐based wireless networks

Mobile IP (MIP) requires mobile nodes (MNs) to register with the home agents (HAs) whenever the MNs change their point of attachment (PoA: access point (AP) or base station (BS)) in different subnets. Thus, such registrations cause excessive signaling overhead and long service delay. To solve this problem, proxy mobile IPv6 (PMIPv6) has been proposed by the IETF NETLMM working group. In PMIPv6, a new entity called mobile access gateway (MAG) performs the mobility‐related signaling with the local mobility anchor (LMA) on behalf of the MN and establishes a tunnel with the LMA. However, a number of MNs must be associated with an MAG, which means that the MAG can be easily overloaded. Therefore, in this paper, we propose a load balancing mechanism among the MAGs in the PMIPv6 network. The PMIPv6 handover signaling procedure is extended to support the proposed load balancing mechanism. We also discuss using IEEE 802.21 Media Independent Handover (MIH) protocol for load balancing to determine the load status at the candidate PoAs, in addition to the load status at the candidate MAGs. To evaluate the performance, we analyze the average waiting time in the queue at the MAG. Through simulations and numerical analysis, we show that the proposed load balancing mechanism can produce less queueing delay at the MAG and a higher data transmission rate at the PoA than when a load balancing operation is not performed in the PMIPv6 network. Copyright © 2009 John Wiley & Sons, Ltd.     

The characteristics of carbon nanotube‐reinforced poly(phenylene sulfide) nanocomposites

Multiwall carbon nanotube reinforced poly (phenylene sulfide) (PPS) nanocomposites were successfully fabricated through melt compounding. Structural, electrical, thermal, rheological, and mechanical properties of the nanocomposites were systematically studied as a function of carbon nanotube (CNT) fraction. Electrical conductivity of the polymer was dramatically enhanced at low loading level of the nanotubes; the electrical percolation threshold lay between 1 and 2 wt % of the CNTs. Rheological properties of the PPS nanocomposites also showed a sudden change with the CNT fraction; the percolation threshold was in the range of 0–0.5 wt % of CNTs. The difference in electrical and rheological percolation threshold was mainly due to the different requirements needed in the carbon nanotube network in different stages. The crystallization and melting behavior of CNT‐filled PPS nanocomposites were studied with differential scanning calorimetry; no new crystalline form of PPS was observed in the nanocomposites, but the crystallization rate was reduced. The thermal and mechanical properties of the nanocomposites were also investigated, and both of them showed significant increase with CNT fraction. For 5 wt % of CNT‐filled PPS composite, the onset of degradation temperature increased by about 13.5°C, the modulus increased by about 33%, and tensile strength increased by about 172%. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Reliable Wavelength-Division-Multiplexed Passive Optical Network Using Novel Protection Scheme

A novel, reliable wavelength-division-multiplexed passive optical network (WDM-PON) with self-protection capability is proposed. By utilizing the routing characteristics of N x N arrayed waveguide grating, the proposed architecture can provide automatic protection against any fiber cut between central office and optical network unit (ONU). Compared with the conventional schemes, this scheme adopts colorless ONUs, thus leading to a decrease in the costs of operation, administration, and maintenance, as well as the production cost. Without the performance degradation, the proposed WDM-PON scheme can offer a reliable network service. In the experiment, the protection performance was demonstrated in the carrier-distributed 1.25-Gb/s WDM transmission over 20-km single-mode fiber.     

Toward distinguishing woodsmoke and diesel exhaust in ambient particulate matter

Particulate matter (PM) from biomass burning and diesel exhaust has distinct X-ray spectroscopic, carbon specific signatures, which can be employed for source apportionment. Characterization of the functional groups of a wide selection of PM samples (woodsmoke, diesel soot, urban air PM) was carried out using the soft X-ray spectroscopy capabilities at the synchrotron radiation sources in Berkeley (ALS) and Brookhaven (NSLS). The spectra reveal that diesel exhaust particulate (DEP) matter is made up from a semigraphitic solid core and soluble organic matter, predominantly with carboxylic functional groups. Woodsmoke PM has no or a less prevalent, graphitic signature, instead it contains carbon-hydroxyl groups. Using these features to apportion the carbonaceous PM in ambient samples we estimate that the relative contribution of DEP to ambient PM in an urban area such as Lexington, KY and St. Louis, MO is 7% and 13.5%, respectively. These values are comparable to dispersion modeling data from nonurban and urban areas in California, and with elemental carbon measurements in urban locations such as Boston, MA, Rochester, NY, and Washington, DC.     

Influences of added surfactants on the water solubility and antibacterial activity of rosemary extract

Food Science and Biotechnology - Rosemary extract (RE) has significant antioxidant and antibacterial properties; however, the application of RE to areas with an aqueous solution is limited due to...     

Structural decomposition of technological domain using patent co-classification and classification hierarchy

Scientometrics - This paper proposes a new method for decomposing a technological domain (TD). Specifically, the method identifies sub-TDs at the different levels of technological hierarchy within...