Comment on ‘Discussion on Barkhausen and Nyquist stability criteria’

This comment is related to the recently published article entitled “On ‘Discussion on Barkhausen and Nyquist stability criteria’, Analog Integrated circuits and signal processing, Vol. 70, pp. 443–449, 2012. In this article the authors considered one of the possible four alternatives of the Wien-bridge oscillator that was previously considered in the article entitled “Discussion on Barkhausen and Nyquist stability criteria”, Analog Integrated Circuits and Signal Processing, Vol. 62, pp. 327–332, 2010, which depicts the failure of Barkhausen criterion concerning the determination of the condition of oscillation startup of sinusoidal oscillation. In the above mentioned articles the operational amplifier used is assumed ideal. In this comment it will be shown that the Wien-bridge oscillator circuit used in the above mentioned articles can behave as a sinusoidal oscillator only at relatively high frequencies when the operational amplifier can be considered non-ideal. At relatively low frequencies; when the operational amplifier can be considered ideal, the same circuit behaves as a relaxation oscillator with a square wave output rather than a sinusoidal output.     

Using Automated Negotiation for Grid Services

The popularity of grid services has widened their application to numerous domains and increased the utilization of computational resources. In order to create more incentives for the resources owners to lease their resources and prevent users from wasting the resources, the introduction of a market-oriented grid is inevitable. However, the issues for the negotiation between service provider and consumer over the supply and demand of resources can be complex, with highly interdependent issues. In this research, a simulated automated negotiation mechanism including a co-evolutionary mechanism and a modified game theory approach is proposed, to assist them in reaching an agreement over the conflicting issues. In the proposed architecture, the co-evolution process is able to reduce the multiple dimensional search space into a two-dimension search space and identify the appropriate negotiation strategies for the negotiating agents to form a payoff matrix which can be used for the game theory related stage of their interaction. The multiple stage negotiation process is introduced to improve the negotiation result. In this paper, an application which requires a large amount of computational resources to process the data generated from mobile devises is used to demonstrate that the proposed system is able to resolve the conflicts and obtain a valid solution.     

Improving throughput of long-hop TCP connections in IP over OPS networks

Optical Packet Switching (OPS) can provide the ever-increasing bandwidth required for Internet traffic and new applications for future networks. However, optical packet loss is the major problem for an OPS network. Moreover, by increasing the number of hops between a pair of ingress–egress switches in an OPS network, optical Packet Loss Rate (PLR) between this pair is increased. Therefore, due to a higher PLR for long-hop TCP connections, the throughput of these connections may be much lower than the short-hop TCP connections. To overcome this problem, it is proposed in this paper to use the retransmission idea in the optical domain not only to increase TCP throughput but also to improve the throughput of multi-hop TCP connections, and also to have a loss-free OPS network. Under retransmission in the optical domain, a copy of the transmitted traffic is kept in the electronic buffers of ingress switches and retransmitted in the optical domain whenever required. Note that the TCP layer has its own retransmission at the client packet level as well. By retransmission of lost packets in the optical domain, TCP would be unaware of the lost client packets, and therefore, TCP would not reduce its sending rate. In this paper, TCP throughput is studied in a bufferless slotted OPS network and the effectiveness of the proposed mechanism is evaluated.

Large-signal analysis of CMOS analogue functional elements using Fourier-series approximations

This paper discusses the large signal performance of CMOS analogue-functional elements. Fourier-series approximations are obtained for the transfer functions of the basic building blocks such as the linear CMOS transconductance element and the CMOS full-wave rectifier. Using these Fourier-series approximations, simple closed-form analytical expressions are obtained for the amplitudes of the harmonics at the output of a basic building block excited by a sinusoidal input signal. The analysis shows that, while the performance of the basic building blocks is near ideal at relatively small input amplitudes, performance degradation increases as the input amplitudes increase. On the other hand, since these expressions ignore the distortion mechanisms resulting from body effect and channel-length modulation, they cannot reliably predict the performance at small input signal levels. It appears, therefore, that body-effect and channel-length modulation must be taken into consideration for small-signal analysis.     

Optimized intrusion detection mechanism using soft computing techniques

Intrusion detection is an important technique in computer and network security. A variety of intrusion detection approaches be present to resolve this severe issue but the main problem is performance. It is important to increase the detection rates and reduce false alarm rates in the area of intrusion detection. Therefore, in this research, an optimized intrusion detection mechanism using soft computing techniques is proposed to overcome performance issues. The KDD-cup dataset is used that is a benchmark for evaluating the security detection mechanisms. The Principal Component Analysis (PCA) is applied to transform the input samples into a new feature space. The selecting of an appropriate number of principal components is a critical problem. So, Genetic Algorithm (GA) is used in the optimum selection of principal components instead of using traditional method. The Support Vector Machine (SVM) is used for classification purpose. The performance of this approach is addresses. Further, a comparative analysis is made with existing approaches. Consequently, this method provides optimal intrusion detection mechanism which is capable to minimize amount of features and maximize the detection rates.     

Performance of Object Classification Using Zernike Moment

Moments have been used in all sorts of object classification systems based on image. There are lots of moments studied by many researchers in the area of object classification and one of the most preference moments is the Zernike moment. In this paper, the performance of object classification using the Zernike moment has been explored. The classifier based on neural networks has been used in this study. The results indicate the best performance in identifying the aggregate is at 91.4% with a ten orders of the Zernike moment. This encouraging result has shown that the Zernike moment is a suitable moment to be used as a feature of object classification systems.     

Web Support System for Business Intelligence in Small and Medium Enterprises

Last decade belongs to business intelligence (BI) because it is one of the few concepts that have actually lived to the expectations. Not only the businesses have adopted it but also have reaped the fruits out of it. But the cost of BI solutions is very high and has restricted small and medium enterprises to use BI solutions. The human resource is also limited and resultantly expensive in this field. This research proposes a web support system for business intelligence which provides automated data mapping and loading from user application to BI framework and also validates it. The system also assists users in getting the outputs in terms of reports and dashboards. The implementation of the proposed framework demonstrates convenience of use and effective cost saving as it does not require any technical expertise. The beauty of this web support system is that all the steps are menu driven and any non-technical user can get hold of it easily.     

Will New Antenna Materials Enable Single Path Multiple Access (SPMA)?

The aim of this paper is to introduce a novel frequency reuse concept especially for macro cellular networks to substantially increase the mobile network capacity, and simultaneously to avoid the implementation of low efficient small cells. Single path multiple access (SPMA) utilizes the characteristics of independent propagation paths for particular geographical location in the coverage area of mobile network. The proposed concept is based on the assumption that new approach will be adopted by the antenna manufacturers for producing advanced antennas by utilizing materials like metamaterials including carbon based nanotechnology, and graphene. In SPMA concept, communication between base station and mobile station happens through only single independent propagation path, and frequency resources can be reused in 5 m  \(\times \)  5 m areas or even more often in 1 m  \(\times \)  1 m areas, but limited by a base station/mobile station antenna requirement. Thus, the capacity of the network will be increased dramatically, and it can be managed in centralized manner at certain macro site locations. In already deployed cellular networks, these macro sites are mostly easily available, and that would help to implement SPMA to enhance the network capacity. Simulation results provided in this paper show the applicability of SPMA technique, by limiting the radiation of signal as single path propagation between base station and mobile station.     

High-performance FIR filter design based on sharing multiplication

Finite impulse response (FIR) filtering can be expressed as multiplications of vectors by scalars. We present high-speed designs for FIR filters based on a computation sharing multiplier which specifically targets computation re-use in vector-scalar products. The performance of the proposed implementation is compared with implementations based on carry-save and Wallace tree multipliers in 0.35-/spl mu/m technology. We show that sharing multiplier scheme improves speed by approximately 52 and 33% with respect to the FIR filter implementations based on the carry-save multiplier and Wallace tree multiplier, respectively. In addition, sharing multiplier scheme has a relatively small power delay product than other multiplier schemes. Using voltage scaling, power consumption of the FIR filter based on computation sharing multiplier can be reduced to 41% of the FIR filter based on the Wallace tree multiplier for the same frequency of operation.     

Bias-temperature instabilities of polysilicon gate HfO/sub 2/ MOSFETs

Bias-temperature instabilities (BTI) of HfO/sub 2/ metal oxide semiconductor field effect transistors (MOSFETs) have been systematically studied for the first time. NMOS positive BTI (PBTI) exhibited a more significant V/sub t/ instability than that of PMOS negative BTI (NBTI), and limited the lifetime of HfO/sub 2/ MOSFETs. Although high-temperature forming gas annealing (HT-FGA) improved the interface quality by passivating the interfacial states with hydrogen, BTI behaviors were not strongly affected by the technique. Charge pumping measurements were extensively used to investigate the nature of the BTI degradation, and it was found that V/sub t/ degradation of NMOS PBTI was primarily caused by charge trapping in bulk HfO/sub 2/ rather than interfacial degradation. Deuterium (D/sub 2/) annealing was found to be an excellent technique to improve BTI immunity as well as to enhance the mobility of HfO/sub 2/ MOSFETs.