A fault-tolerant and congestion-aware architecture for wireless networks-on-chip

Wireless Networks - The combination of traditional wired links for regular transmissions and express wireless paths for long distance communications is a promising solution to prevent multi-hop...     

Development and Simulation of Sulfur‐doped Graphene Supported Platinum with Exemplary Stability and Activity Towards Oxygen Reduction

Sulfur‐doped graphene (SG) is prepared by a thermal shock/quench anneal process and investigated as a unique Pt nanoparticle support (Pt/SG) for the oxygen reduction reaction (ORR). Particularly, SG is found to induce highly favorable catalyst‐support interactions, resulting in excellent half‐cell based ORR activity of 139 mA mg_Pt ^?1 at 0.9 V vs RHE, significant improvements over commercial Pt/C (121 mA mg_Pt ^?1) and Pt‐graphene (Pt/G, 101 mA mg_Pt ^?1). Pt/SG also demonstrates unprecedented stability, maintaining 87% of its electrochemically active surface area following accelerated degradation testing. Furthermore, a majority of ORR activity is maintained, providing 108 mA mg_Pt ^?1, a remarkable 171% improvement over Pt/C (39.8 mA mg_Pt ^?1) and an 89% improvement over Pt/G (57.0 mA mg_Pt ^?1). Computational simulations highlight that the interactions between Pt and graphene are enhanced significantly by sulfur doping, leading to a tethering effect that can explain the outstanding electrochemical stability. Furthermore, sulfur dopants result in a downshift of the platinum d‐band center, explaining the excellent ORR activity and rendering SG as a new and highly promising class of catalyst supports for electrochemical energy technologies such as fuel cells.     

Personal identification using feature and score level fusion of palm- and fingerprints

The ever increasing demand of security has resulted in wide use of Biometric systems. Despite overcoming the traditional verification problems, the unimodal systems suffer from various challenges like intra class variation, noise in the sensor data etc, affecting the system performance. These problems are effectively handled by multimodal systems. In this paper, we present multimodal approach for palm- and fingerprints by feature level and score level fusions (sum and product rules). The proposed multi-modal systems are tested on a developed database consisting of 440 palm- and fingerprints each of 55 individuals. In feature level fusion, directional energy-based feature vectors of palm- and fingerprint identifiers are combined to form joint feature vector that is subsequently used to identify the individual using a distance classifier. In score level fusion, the matching scores of individual classifiers are fused by sum and product rules. Receiver operating characteristics curves are formed for unimodal and multimodal systems. Equal Error Rate (EER) of 0.538% for feature level fusion shows best performance compared to score level fusion of 0.6141 and 0.5482% of sum and product rules, respectively. Multimodal systems, however, significantly outperform unimodal palm- and fingerprints identifiers with EER of 2.822 and 2.553%, respectively.     

Thermoelectric Effect Spectroscopy and Photoluminescence of High-Resistivity CdTe:In

Thermoelectric effect spectroscopy and photoluminescence techniques were used to study the defect levels in samples from three crystals of CdTe:In grown by the vertical gradient freeze method. The main goal of the investigation was to study defects, which strongly trap charge carriers or act as recombination centers in order to eliminate them from the technological process. The main difference among detecting and non-detecting samples was the absence of electron traps with a very high capture cross-section and energy 0.6 eV to 0.7 eV, which act as lifetime killers even at low concentrations. Recently published ab initio calculations show a complex of Te antisite and Cd vacancy within this energy range.     

A Zero-Pole Reposition Based, 0.95-mW, 68-dB,Linear-in-dB,Constant-Bandwidth Variable Gain Amplifier

A variable-gain amplifier with very low power consumption and wide tuning range is presented. The operational principle of this unique structure is discussed, its most important formulas are derived and its outstanding performance is verified by simulation in TSMC 0.18-μm N-well CMOS fabrication process. Owing to the novel zero-pole repositioning technique, the proposed circuit demonstrates very high frequency bandwidth of 79 MHz while drawing only 0.52 mA from 1.8 V power supply. The interesting results such as a very small core area of about 0.0025 mm² as well as a wide linear-in-dB and constant-bandwidth tuning range of 68.2 dB along with a very low power consumption of 0.95 mW are achieved utilizing standard CMOS technology. The stability of the proposed VGA is verified through transient sinusoidal response analysis. Full process, voltage and temperature (PVT) variation analysis of the circuit is also investigated through Monte Carlo and corner case analysis in order to approve the robustness of the structure. Monte Carlo simulations show standard deviation values of 4.6 dB and 78.3 MHz in gain and gain-bandwidth product, respectively. These results show that our zero-pole repositioning method would lend itself well for use in low-power and high-frequency applications, especially in high-speed automatic gain control amplifiers.     

An Enhanced Cooperative Communication Scheme for Physical Uplink Shared Channel in NB-IoT

Wireless Personal Communications - Smart Home is one of the most established applications of the Internet of Things. Almost every equipment we use in our daily life—appliances, electric...     

A novel ±0.5 V,high current drive,and rail to rail current operational amplifier

A current operational amplifier (COA) with very high current drive capability is presented in this paper. The principle of operation of this unique structure is discussed, its most important formulas are derived and its outstanding performance is verified by HSPICE simulation in TSMC 0.18 μm CMOS, BSIM3, and Level49 technology. Owing to the elaborately arranged components, the proposed circuit demonstrates very high frequency bandwidth, extremely high CMRR, high output impedance, and true rail to rail output voltage swing range while operating at very low power supply of ±0.5 V. The interesting results such as current drive capability of ±1 mA, high output impedance of 5 GΩ, wide gain bandwidth of 220 MHz, extremely high output voltage swing of ±0.45 V, which interestingly provides the highest yet reported output voltage compliance for current mode building blocks implemented by regular CMOS technology, low static power consumption of 159 μW, and very high CMRR of 155 dB is achieved utilizing standard CMOS technology. Full process, voltage, and temperature variation analysis of the circuit is also investigated in order to approve the well robustness of the structure. The transient stepwise and sinusoidal response analysis is also done to verify the proposed COA stability.     

Analysis of leaky bucket mechanism based on burstiness characterization

In high-speed networks, a congestion control strategy has to manage bandwidth allocation based on the characteristics of input traffic sources. Accordingly, the definition of traffic characterization becomes significant in all aspects concerning network performance. In this paper, the burstiness characterization of a traffic stream is based on a virtual queue principle. We study the leaky bucket mechanism as a regulator element that controls input traffic before access to a newwork, as well as inside a network. To protect an input traffic stream, we investigate the optimal parameter settings of a leaky bucket. In addition, we analyse the worst case performance, and obtain upper bounds on loss probability and packet delay. We also determine the characteristics of an output stream in the worst case. Such performance bounds reveal the effectiveness of a leaky bucket, and provide enough information for the QOS satisfaction of the network users.     

Performance evaluation of OFDM and single‐carrier systems using frequency domain equalization and phase modulation

In this paper, we study the performance of the continuous phase modulation (CPM)‐based orthogonal frequency division multiplexing (CPM‐OFDM) system. Also, we propose a CPM‐based single‐carrier frequency domain equalization (CPM‐SC‐FDE) structure for broadband wireless communication systems. The proposed structure combines the advantages of the low complexity of SC‐FDE, in addition to exploiting the channel frequency diversity and the power efficiency of CPM. Both the CPM‐OFDM system and the proposed system are implemented with FDE to avoid the complexity of the equalization. Two types of frequency domain equalizers are considered and compared for performance evaluation of both systems; the zero forcing (ZF) equalizer and the minimum mean square error (MMSE) equalizer. Simulation experiments are performed for a variety of multipath fading channels. Simulation results show that the performance of the CPM‐based systems with multipath fading is better than their performance with single path fading. The performance over a multipath channel is at least 5 and 12 dB better than the performance over a single path channel, for the CPM‐OFDM system and the proposed CPM‐SC‐FDE system, respectively. The results also show that, when CPM is utilized in SC‐FDE systems, they can outperform CPM‐OFDM systems by about 5 dB. Copyright © 2010 John Wiley & Sons, Ltd.     

The effect of heat treatments on the properties of Ti/Pt heating elements for gas sensor applications

Ti/Pt as heating element for gas sensor applications was fabricated on silicon (Si) wafer substrate. The fabricated device was subjected to heat treatment at different prescribed time periods for thermal stability. The energy dispersion spectroscopy (EDS) results of the device indicated that there were no Ti traces on the Pt surface after heat treatment at 450 °C for 3 and 4 h in an argon (Ar) atmosphere. A maximum temperature coefficient of resistance (TCR) with a value of 2.88×10^?3 K^?1 was obtained for the device with 3 h heat treatment.