Integer Linear Programming-Based Bit-Level Optimization for High-Speed FIR Decimation Filter Architectures

Analog-to-digital converters based on sigma-delta modulation have shown promising performance, with steadily increasing bandwidth. However, associated with the increasing bandwidth is an increasing modulator sampling rate, which becomes costly to decimate in the digital domain. Several architectures exist for the digital decimation filter, and among the more common and efficient are polyphase decomposed finite-length impulse response (FIR) filter structures. In this paper, we consider such filters implemented with partial product generation for the multiplications, and carry-save adders to merge the partial products. The focus is on the efficient pipelined reduction of the partial products, which is done using a bit-level optimization algorithm for the tree design. However, the method is not limited only to filter design, but may also be used in other applications where high-speed reduction of partial products is required. The presentation of the reduction method is carried out through a comparison between the main architectural choices for FIR filters: the direct-form and transposed direct-form structures. For the direct-form structure, usage of symmetry adders for linear-phase filters is investigated, and a new scheme utilizing partial symmetry adders is introduced. The optimization results are complemented with energy dissipation and cell area estimations for a 90 nm CMOS process.     

Performance evaluation of selected Transmission Control Protocol variants over a digital video broadcasting‐second generation broadband satellite multimedia system with QoS

This paper presents an analysis of several Transmission Control Protocol (TCP) variants working over a digital video broadcasting‐second generation (DVB‐S2) satellite link with the support of the Differentiated Services (DiffServ) architecture to provide quality of service (QoS). This analysis is carried out using the NS‐2 simulator tool. Three TCP variants are considered: SACK TCP, Hybla TCP, and CUBIC TCP. These TCP variants are taken as a starting point because they have proven to be the most suitable variants to deal with long delays present in satellite links. The DVB‐S2 link also introduces the challenge of dealing with variable bandwidth, whereas the DiffServ architecture introduces the challenge of dealing with different priorities. In this paper, we propose a DiffServ model that includes a modified queuing mechanism to enhance the goodput of the assured forwarding traffic class. This modified DiffServ model is simulated and tested, considering the interaction of the selected TCP variants. In addition, we present evaluation metrics, significant simulations results, and conclusions about the performance of these TCP variants evaluated over the proposed scenario. As a general conclusion, we show that CUBIC TCP is the TCP variant that shows the best performance in terms of goodput, latency, and friendliness. Copyright © 2012 John Wiley & Sons, Ltd.     

Modeling the user interface

The application of an object-oriented approach to modeling the application and presentation layer of the human-machine interfaces in a telecommunications management network architecture is described. It is argued that a significant simplification in information interchange between human and machine occurs when the machine has a model of the user to which it can conform. Several aspects of user modeling are discussed. The development and implementation of new input devices are also discussed     

Efficient detection of missing tags for passive RFID systems

One of the most interesting radio‐frequency identification applications is the detection of missing tags along with the objects they are attached to. This process must be executed in a fast and efficient way. A monitoring function may need to be periodically executed in order to implement a reliable detection system, therefore raising the need to optimize its performance, in terms of both time and reliability. The contribution of this paper is twofold; on one hand, we provide a protocol taxonomy for the missing‐tag detection problem, which up to our best knowledge is the first of its class, and on the other hand, we propose two novel protocols for a fast detection of the missing tags in a passive radio‐frequency identification system. By increasing the length of the packets exchanged among the reader and the tags, our protocols are able to reduce the time needed to detect the missing tags, by decreasing the number of broadcast messages in the network. Our results show that our proposals outperform the most recent protocols in the literature, obtaining improvements on the execution time going from 25% to 75%. Copyright © 2016 John Wiley & Sons, Ltd.     

An infrastructure for detecting and punishing malicious hosts using mobile agent watermarking

Mobile agents are software entities consisting of code, data, and state that can migrate autonomously from host to host executing their code. In such scenario there are some security issues that must be considered. In particular, this paper deals with the protection of mobile agents against manipulation attacks performed by the host, which is one of the main security issues to solve in mobile agent systems. This paper introduces an infrastructure for mobile agent watermarking (MAW). MAW is a lightweight approach that can efficiently detect manipulation attacks performed by potentially malicious hosts that might seek to subvert the normal agent operation. MAW is the first proposal in the literature that adapts software watermarks to verify the execution integrity of an agent. The second contribution of this paper is a technique to punish a malicious host that performed a manipulation attack by using a trusted third party (TTP) called host revocation authority (HoRA). A proof‐of‐concept has also been developed and we present some performance evaluation results that demonstrate the usability of the proposed mechanisms. Copyright © 2010 John Wiley & Sons, Ltd.     

Metal contact properties of poly3-octylthiophene thin films

Chemically synthesized undoped poly3-octylthiophene (P3OT) was deposited as thin films on conducting glass substrates by drop casting. Doping state of P3OT was obtained by adding FeCl₃ into the original P3OT solution. A qualitative explanation of the electrical contact behavior of the P3OT films was given by a band diagram made from optical absorbance spectra and electrochemical current–voltage curves of the polymeric films. Gold contacts on both undoped and doped P3OT films give an ohmic contact. Silver/P3OT contact shows a rectifying behavior; the forward current is 500 times the reverse current at 0.5 V. Aluminum also forms rectifying contact with the two types of P3OT films, although the experimental rectification ratio is lower than that of the silver. The I–V curves of rectifying contacts were analyzed with Schottky equation and different diode parameters were obtained.     

Influence of size and polarity of residue 31 in porcine pancreatic phospholipase A2 on catalytic properties

Residue 31 of porcine pancreatic phospholipase A₂ (PLA₂) islocated at the entrance to the active site. To study the roleof residue 31 in PLA₂, six mutant enzymes were produced by site-directedmutagenesis, replacing Leu by either Trp, Arg, Ala, Thr, Seror Gly. Direct binding studies indicated a three to six timesgreater affinity of the Trp31 PLA₂ for both monomeric and micellarsubstrate analogs, relative to the wild-type enzyme. The otherfive mutants possess an unchanged affinity for monomers of theproduct analog n-decylphosphocholine and for micelles of thediacyl substrate analog rac-l,2-dioctanoylamino-dideoxy-glycero-3-phosphocholine.The affinities for micelles of the monoacyl product analog n-hexadecylphosphocholinewere decreased 9–20 times for these five mutants. Kineticstudies with monomeric substrates showed that the mutants haveV_max values which range between 15 and 70% relative to the wild-typeenzyme. The V_max values for micelles of the zwitterionic substratel,2-dioctanoyl-sn-glycero-3-phosphocholine were lowered 3–50times. The K_m values for the monomeric substrate and the k_mvalues for the micellar substrate were hardly affected in thecase of five of the six mutants, but were considerably decreasedwhen Trp was present at position 31. The results of these investigationspoint to a versatile role for the residue at position 31: involvementin the binding and orientating of monomeric substrate (analogs),involvement in the binding of the enzyme to micellar substrateanalogs and possibly involvement in shielding the active sitefrom excess water.     

Fast Multi-Hypothesis Motion Compensated Filter for Video Denoising

Multi-Hypothesis motion compensated filter (MHMCF) utilizes a number of hypotheses (temporal predictions) to estimate the current pixel which is corrupted with noise. While showing remarkable denoising results, MHMCF is computationally intensive as full search is employed in the expectation of finding good temporal predictions in the presence of noise. In the frame of MHMCF, a fast denoising algorithm FMHMCF is proposed in this paper. With edge preserved low-pass prefiltering and noise-robust fast multihypothesis search, FMHMCF could find reliable hypotheses while checking very few search locations, so that the denoising process can be dramatically accelerated. Experimental results show that FMHMCF can be 10 to 14 times faster than MHMCF, while achieving the same or even better denoising performance with up to 1.93 dB PSNR (peak-signal-noise-ratio) improvement.     

A Discretized Approach to Air Pollution Monitoring Using UAV-based Sensing

Mobile Networks and Applications - Recently, Unmanned Aerial Vehicles (UAVs) have become a cheap alternative to sense pollution values in a certain area due to their flexibility and ability to...     

DBA algorithm for the support of multi-tiered bandwidth guarantee in Ethernet passive optical networks

Access Networks based on Passive Optical Network (PON) technology can offer transport services to broadband service providers, such as mobile backhauling/fronthauling for Mobile Network Operators and multi-ONU Service Level Agreements for Virtual Network Operators. Besides that, Infrastructure Service Provider (InP) also provides broadband access services to end-users, such as residential subscribers and single or multi-site enterprises. In such a scenario, the InPs support diverse customers in the same PON. This paper proposes a bandwidth slicing mechanism to assure bandwidth isolation for different PON customers who rent part of a PON infrastructure from the InP. We introduce a Dynamic Bandwidth Allocation algorithm for Ethernet PONs called MAB-IPACT, which assures bandwidth on different granularity: conventional customers with a single ONU, multi-ONU customers owning a group of ONUs and providing a single type of service, and multi-ONU customers having diverse types of services. The MAB-IPACT algorithm also prioritizes bandwidth distribution among subgroups of ONUs of the same multi-ONU customer. A subgroup of ONUs is a subset of ONUs that belongs to the same multi-ONU customer, which are employed for the same type of service (e.g., ONUs for business service.). Simulation results show that the proposed mechanism improves the network performance of multi-ONU customers with subgroups of ONUs serving different services.