The role of local storage in supporting video retrieval services onATM networks

This paper studies a reference network architecture for video information retrieval, based on hierarchical storage of the video segments and asynchronous transfer mode (ATM) transport capability on the long distance network. The storage associated to local switching nodes can be exploited in two complementary ways, either for caching the most requested video programs, and for decoupling the transmission speed on the long distance network from the natural playout speed of the video segments. We show that both approaches lead to a substantial increase of the load carried on the long distance network with a given service requirement. Moreover, we show that a greater efficiency is obtained when a suitable integration of the two approaches is considered     

SVD-Based Techniques for Zero-Padded Block Transmission Over Fading Channels

In this paper, the performance of filter bank transceivers in the presence of a dispersive time-variant channel is investigated. It is well known that filter bank transceivers can be adapted to the channel transfer function to yield intersymbol interference (ISI) cancellation. When the channel is time variant, several problems arise, since the transceiver should be changed whenever the channel evolves. In this paper, we will allow both the transmitter and the receiver to change and satisfy the interference-free condition, under the assumption of a zero-padded block transmission. In this case, the optimum transmitter-receiver pair can be computed by using a singular value decomposition (SVD) of the channel matrix. A fast receiver adaptation based on SVD tracking is presented. Simulation results show that minimum performance loss with respect to the optimum receiver can be achieved for our reduced complexity receiver     

Impact of Stator Winding of a Five-Phase Permanent-Magnet Motor on Postfault Operations

The performance of a five-phase permanent-magnet (PM) motor is analyzed under postfault conditions. Proper current control strategies are adopted so as to guarantee safe drive operation after any fault occurrence. This paper covers three fault types: the open circuit condition of a single phase, the open circuit condition of two nonadjacent phases, and the open circuit condition of two adjacent phases. Two motors with two different windings (with double and single layers, respectively) are compared under each fault type. This paper aims to highlight the difference in the motor performance of motors adopting these two different windings. A further novelty of this paper is that the proper current control strategies are derived analytically, including not only the fundamental harmonic of the flux-density distribution but also the higher harmonics. It is shown that these harmonics cause high torque oscillations. Owing to this analytical approach, the strategy can be applied to a variety of PM motors. In addition, the postfault current waveforms remain sinusoidal, making the current control easier. For each fault type, the results of both simulations and experimental tests are included. A good match between analytical predictions and experimental tests validates the proposed current control strategies.     

Smashing OpenFlow's “atomic” actions: Programmable data plane packet manipulation in hardware

Recently, with new hardware architectures such as Reconfigurable Match Tables and languages such as P4, the Software Defined Networking community has started to bring line‐rate data plane programmability inside switching chipsets. Starting from the original OpenFlow's match/action abstraction, most of the work has so far focused on key improvements in matching flexibility. Conversely, the “action part,” ie, the set of operations (such as encapsulation or header manipulation) performed on packets after the forwarding decision, has received way less attention. Goal of this paper is to move beyond the idea of “atomic,” preimplemented, actions, and rather make them programmable while retaining high speed multi‐Gbps operation. To this purpose, we propose a domain‐specific HW architecture, called Packet Manipulation Processor (PMP), able to efficiently implement such actions. Both a PMP C++ instruction set simulator and a NetFPGA prototype have been developed. The performances of the PMP have been verified with three nontrivial use cases (tunneling, NAT, and ARP reply generation), showing that also in the worst case the throughput is well above 10 Gbps.     

Biomimetic Hydroxyapatite–Drug Nanocrystals as Potential Bone Substitutes with Antitumor Drug Delivery Properties

This Full Paper investigates the adsorption and desorption of the anticancer drugs cis‐diamminedichloroplatinum(II) (CDDP, cisplatin) and the new platinum(II) complex di(ethylenediamineplatinum)medronate (DPM), as well as the clinically relevant bisphosphonate alendronate, towards two biomimetic synthetic HA nanocrystalline materials with either plate‐shaped (HAps) or needle‐shaped (HAns) morphologies and different chemico‐physical properties. The adsorption and desorption kinetics are dependent on the specific properties of the drugs and the morphology of the HA nanoparticles. Adsorption of the platinum complexes occurs with retention of the nitrogen ligands but the chloride ligands of cisplatin are displaced. Despite their opposite charges, the negatively charged alendronate bisphosphonate and the positively charged aquated cisplatin are strongly adsorbed, while the neutral DPM complex shows lower affinity towards the negatively charged apatitic surface. The data suggest that adsorption of the two platinum complexes is driven by electrostatic attractions, while interaction between the alendronate and the HA surface takes place by ligand exchange in which the two phosphonate groups of the drug molecule replace two surface phosphate groups. Significantly, adsorption of positively charged hydrolysis species of cisplatin is more favored on the phosphate‐rich HAns surface while adsorption of negatively charged alendronate is more favored on the calcium‐rich HAps surface. The latter type of short‐range electrostatic interactions also appear to dominate the desorption kinetics; consequently, drug release is greater for neutral DPM than for charged alendronate and aquated cisplatin. Moreover, while the release per unit area of charged species is the same for the two types of HAs, the release of DPM is faster from HAns, which is lower in surface calcium, than for HAps. Overall, this work demonstrates that the properties of HA nanocrystals can be modulated in such a way to produce HA/biomolecule conjugates tailored for specific therapeutic applications.     

Asymptotically Efficient Reduced Complexity Frequency Offset and Channel Estimators for Uplink MIMO-OFDMA Systems

In this paper, we address the joint data-aided estimation of frequency offsets and channel coefficients in uplink multiple-input multiple-output orthogonal frequency-division multiple access (MIMO-OFDMA) systems. As the maximum-likelihood (ML) estimator is impractical in this context, we introduce a family of suboptimal estimators with the aim of exhibiting an attractive tradeoff between performance and complexity. The estimators do not rely on a particular subcarrier assignment scheme and are, thus, valid for a large number of OFDMA systems. As far as complexity is concerned, the computational cost of the proposed estimators is shown to be significantly reduced compared to existing estimators based on ML. As far as performance is concerned, the proposed suboptimal estimators are shown to be asymptotically efficient, i.e., the covariance matrix of the estimation error achieves the Cramer-Rao bound when the total number of subcarriers increases. Simulation results sustain our claims.     

Crosslinking kinetics of SBR composites containing vulcanized ground scraps as filler

The aim of this study was to characterize the cure reaction of styrene–butadiene rubber (SBR) composites containing industrial rubber scraps. Different proportions of SBR ground scraps (SBR-r), varying from 10 to 80 parts per hundred of rubber, were incorporated into a base formulation of identical composition. Crosslink formation and the kinetics of the cure reaction were evaluated through oscillatory disk rheometry, differential scanning calorimetry, and crosslink density. Cure characteristics, such as scorch time and cure time, decreased with increasing SBR-r content. Minimum torque indicated only a small variation in the viscosity with the incorporation of SBR-r. The maximum torque decreased with the addition of scrap rubber, as a consequence of the reduction in virgin rubber content where crosslinks had been formed. Crosslink density values corroborated these findings, presenting a slight decrease with the increase in the SBR-r content. The kinetic study indicated lower enthalpy values for SBR-r composites compared to those of the control sample. The kinetic parameters, such as activation energy and reaction order, indicated a change in the mechanism of reaction, related to the increased complexity of the systems.     

Accelerated aging of elastomeric composites with vulcanized ground scraps

The aim of this work is to study the effect of thermal aging on the mechanical, dynamic‐mechanical, and chemical properties of SBR (styrene‐butadiene rubber) composites filled with SBR industrial rubber scraps. Eight composites with varying proportions (10–80 phr) of the SBR ground scraps (SBR‐r) were prepared and subjected to accelerated aging in an air‐oven. The composites were evaluated, and the results were compared with a control sample (base formulation with 0 phr of SBR‐r), before and after thermal aging. The accelerated aging led to a decrease in the mechanical properties as a result of an increase in the stiffness of the material, related to an increase in the crosslink density. However, these properties were not affected by the addition of rubber scraps up to 50 phr, either before or after aging. The increase in the glass transition temperature of the composites after aging, measured using dynamic mechanical analysis, confirmed the occurrence of a postcrosslinking process. Fourier transform infrared spectroscopy and crosslink density revealed that the aging mechanism was dependent on the SBR‐r content. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

An overview of poly(vinyl alcohol) and poly(vinyl pyrrolidone) in pharmaceutical additive manufacturing

Recently, drug personalization has received noticeable attention. Problems arising from standard generalized drug treatments have aroused over the years, particularly among pediatric and geriatric patients. The growing awareness of the limitations of the “one-size-fits-all” approach has progressively led to a rethinking of the current medicine's development, laying the basis of personalized medicine. Three-dimensional printing is a promising tool for realizing personalized therapeutic solutions fitting specific patient needs. This technology offers the possibility to manufacture drug delivery devices with tailored doses, sizes, and release characteristics. Among additive manufacturing techniques, fused deposition modeling (FDM) is the most studied for oral drug delivery device production due to its high precision and cheapness. By playing with factors such as drug loading method, filament production, and printing parameters, the medication release profile of a drug delivery device produced by 3D printing can be tailored depending on the patient's requirements. This review focuses on the applications of FDM in drug fabrication using poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) as drug-loaded matrices. The authors aim to provide an overview of the current trends in this research field, with special attention to the effect of the printing parameters, tablet shape, and drug distribution and concentration on drug customization and personalized drug release.     

Fibers based on cellulose‐chitin blends

Fibers made of cellulose (CE) and chitin (CH) in different proportion were wet spun from solutions in dimethylacetamide containing 5% LiCl (w/w). Polymer concentration was purposely maintained as low as possible (?2.4% w/w). Moreover, dope temperature was 60°C to have good spinability. Comparison of the elastic modulus (E) of fibers “as spun” at different CE/CH ratio showed a synergy between the components: at CE/CH ? 50/50, E is ?15 GPa with respect to ?9 and ?11 GPa for neat CE and CH fibers, respectively. Application of a pull‐off ratio during the coagulation allows the E value to increase further. These results, as well as the electronic microscopy of fibers section, agree with a complete miscibility of two polymers at the solid state, probably enhanced by the presence of LiCl. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1825–1831, 2002