A versatile window function for linear ion drift memristor model – A new approach

The memristor is a nano-scaled resistive switching device which is widely investigated in analog and digital applications. We report here our success in formulating a new window function as applicable to linear ion drift model. Accordingly, this paper identifies the demerits of other existing window functions and the requirement of a versatile window function to mimic the current-voltage characteristics of a physical memristor device. The proposed new window function overcomes the demerits of existing window functions such as boundary effect, boundary lock (with respect to frequency of operation), and the scalability. The main significance of proposed model is to facilitate the nonlinearity in linear ion drift memristor model that produces the pinched hysteresis loop (a signature of a memristor) for any typical applied voltage within the frequency range (0.05 ≤ f < 2 Hz). The validation of which has been verified in a memristor based op-amp circuitry. It exhibits a high gain compared to other existing models and produces low power dissipation compared to CMOS based op-amp.     

Model-driven engineering of Manufacturing Automation Software Projects – A SysML-based approach

This paper comprises a SysML-based approach to support the model-driven engineering (MDE) of Manufacturing Automation Software Projects (MASP). The Systems Modeling Language (SysML) is adapted to define the SysML-AT (SysML for automation), a specialized language profile that covers (non-)functional requirements, corresponding software applications and properties of proprietary hardware components. Furthermore, SysML-AT supports an automated software generation for run-time environments conforming to IEC 61131-3. A prototypical tool support was realized for adapted SysML Parametric Diagrams (PD) inside an industrial automation software development tool. Coupling the model editor and online data from the provided run-time environment enables direct debugging inside the model. The approach was evaluated by several case studies and additional usability experiments. With the latter, the suitability of the MDE approach for future users was proven.     

Robustness Validation – A physics of failure based approach to qualification

Product reliability is crucial to the success of a company. Product qualification today is based on standards that follow a stress-test driven approach, meaning pre-defined stress tests with pre-defined stress conditions. However, reliability requirements have increased, while at the same time both designs of semiconductor components and usage of these components in the applications have increasingly been pushed to the limits. This development raises the question, how far the standard procedures are still suitable for reliability assessment. Robustness Validation is an approach to a failure-mechanism-driven qualification that was primarily initiated by the automotive industry but has a much wider range of applicability. The paper will give an introduction to the basic ideas of Robustness Validation. Some limitations including statistical aspects will also be discussed.     

A new approach to the design and analysis of peer‐to‐peer mobile networks

This paper introduces a new model and methodological approach for dealing with the probabilistic nature of mobile networks based on the theory of random graphs. Probabilistic dependence between the random links prevents the direct application of the theory of random graphs to communication networks. The new model, termed Random Network Model, generalizes conventional random graph models to allow for the inclusion of link dependencies in a mobile network. The new Random Network Model is obtained through the superposition of Kolmogorov complexity and random graph theory, making in this way random graph theory applicable to mobile networks. To the best of the authors' knowledge, it is the first application of random graphs to the field of mobile networks and a first general modeling framework for dealing with adhoc network mobility. The application of this methodology makes it possible to derive results with proven properties. The theory is demonstrated by addressing the issue of the establishment of a connected virtual backbone among mobile clusterheads in a peertopeer mobile wireless network. Using the Random Network Model, we show that it is possible to construct a randomized distributed algorithm which provides connectivity with high probability, requiring exponentially fewer connections (peertopeer logical links) per clusterhead than the number of connections needed for an algorithm with a worst case deterministic guarantee.     

A data-driven approach to diagnostics of repetitive processes in the distribution domain – Applications to gearbox diagnostics in industrial robots and rotating machines

This paper presents a data-driven approach to diagnostics of systems that operate in a repetitive manner. Considering that data batches collected from a repetitive operation will be similar unless in the presence of an abnormality, a condition change is inferred by comparing the monitored data against an available nominal batch. The method proposed considers the comparison of data in the distribution domain, which reveals information of the data amplitude. This is achieved with the use of kernel density estimates and the Kullback–Leibler distance. To decrease sensitivity to disturbances while increasing sensitivity to faults, the use of a weighting vector is suggested which is chosen based on a labeled dataset. The framework is simple to implement and can be used without process interruption, in a batch manner. The approach is demonstrated with successful experimental and simulation applications to wear diagnostics in an industrial robot gearbox and for diagnostics of gear faults in a rotating machine.     

Understanding and predicting the motivators of mobile music acceptance – A multi-stage MRA-artificial neural network approach

The adoption level of digital music is still at its formative stage although the adoption renders advantageous to consumers. Therefore, the study develops a model to predict on the motivation leading to consumer’s intention to adopt mobile music services by extending Perceived Cost (PC), Perceived Credibility (PCr), Social Influence (SI), and Personal Innovativeness (INNO) with Technology Acceptance Model (TAM). 160 Respondents were tested using a multi-stage Multiple Regression Analysis (MRA) and Artificial Neural Network (ANN) approach. A non-linear non-compensatory Multi Layer Perceptron (MLP) ANN with feed-forward back-propagation algorithm and ten cross-validation neural networks was deployed in order to capture the motivators of mobile music adoption. All predictor variables were found to have relevance to the output neuron based on the non-zero synaptic weights connected to the hidden neurons. The RMSE values indicated that the ANN models were able to predict the motivators with very high accuracy. The ANN models have out-performed the MRA models as they are able to capture the non-linear relationships between the predictor and criterion variables. While the study found that TAM is a significant predictor, the insignificance linear relationships of PCr and INNO requires further investigation. The music industry can use the findings from this study beneficially to the development of mobile music adoption.     

Experimental investigations and numerical simulation of the electron flow shaped by Grigor’ev-Shesterkin matrix carbon field-emission cells

The results of the investigations of the electron flow in Grigor’ev-Shesterkin field-emission cathode cells intended for use in microwave tubes are presented. It is shown that it is possible to develop electron-optical systems (EOSs) with field-emission cathode matrices for O-type microwave tubes whose beam emittance is similar to the that of the EOSs with grids and hot cathodes.     

Electromigration performance of Through Silicon Via (TSV) – A modeling approach

The electromigration (EM) performance of Through Silicon Via (TSV) in silicon interposer application are studied using Finite Element (FE) modeling. It is found that thermo-mechanical stress is the dominant contribution factor to EM performance in TSV instead of the current density. The predicted failure site is dependent on the process technology, and exhibits asymmetric behavior if different process is used between the top and bottom metallization of a TSV. Modeling is also done for two different coverage patterns of top metallization, namely (i) the metal line covers the via completely, and (ii) the metal line only extends to the centre of the via, covering half of the via. The simulation results of the latter model show the existence of a second EM failure site and worse EM performance is expected. This additional possible EM failure site is further confirmed through dynamic simulation of void growth.     

Interface and interconnection stresses in electronic assemblies – A critical review of analytical solutions

The closed-form solutions for the interfacial stresses in assemblies constituting of two relatively stiff adherends sandwiching a relatively compliant adhesive layer are reviewed. The closed-form solutions are categorised into the “non-free edge solutions” that do not satisfy the nil-shear stress condition at the free edge of the adhesive and the “free edge solutions” that do. Being strength of material solutions, the non-free edge solutions are significantly simpler in form. On the other hand, the solutions tend to grossly underestimate the magnitude of the peeling stress at the free edge. Almost all classical “non-free edge solutions” suffer from two setbacks: (i) assumed σ_a = 0, thus severely underestimating the magnitude of the peeling stress; and (ii) neglected the thickness of the adhesive in their formulation of the x-compliance of assemblies and the evaluation of the effective bending strain on adherends; the former leads to overestimation while the latter leads to gross underestimation of the shear stress (and hence, σ_a(l)). These are demonstrated in a numerical exercise in which two widely followed “non-free edge solutions” and a simplified “free edge solutions” are benchmarked against the finite element analysis.     

A new approach to long‐range dependence in variable bit rate video traffic

Recently it has been observed that variable bit rate (VBR) video traffic displays long‐range dependence, which suggests that traditional Markovian models may not be suitable for performance evaluation of telecommunications networks carrying this traffic. Inspection of the bit rate profile of VBR video traffic suggests that shifting level processes might be more appropriate for this task. In this paper we show that a particular class of these processes matches the autocorrelation and bit rate distribution of real VBR video traffic, including exhibiting long‐range dependent behaviour. This revised version was published online in June 2006 with corrections to the Cover Date.     

Development of a new diindenopyrazine–benzotriazole copolymer for multifunctional application in organic field-effect transistors,polymer solar cells and light-emitting diodes

A new donor–acceptor (D?A) copolymer (PIPY–DTBTA) containing 6,12-dihydro-diindeno[1,2-b;1′,2′-e]pyrazine donor and benzotriazole acceptor was synthesized and characterized for multifunctional applications in organic field-effect transistors (OFETs), polymer solar cells (PSCs) and polymer light-emitting diodes (PLEDs). The polymer exhibits high molecular weights, excellent film-forming ability, a deep HOMO energy level, and good solution processability. Solution-processed thin film OFETs based on this polymer revealed good p-type characteristic with a high hole mobility up to 0.0521 cm² V^?1 s^?1. Bulk-heterojunction PSCs comprising this polymer and PC₆₁BM gave a power conversion efficiency (PCE) of 0.77%. The single-layer PLEDs based on PIPY–DTBTA emitted a yellow–red light with a maximum brightness of 385 cd m^?2 at the turn-on voltage of 6 V.     

Application of ABCD Formalism in Theoretical and Experimental Analysis of Actively Modelocked Fiber Laser

Time domain ABCD matrix formalism is a useful model for analyzing the characteristics of actively modelocked fiber laser.Based on this model and given more consideration on the influences of optical fiber dispersion and optical fiber nonlinearity,the laser characteristic of actively modelocked fiber laser is analyzed,and the comparision of the theoretical analsis results with experimental ones is given.     

Interrelationship between structural,optical and transport properties of InP1−xBix: DFT approach

In this paper, the effect of Bi concentrations on the electronic structure, optical and thermoelectric properties was studied, using the density functional theory. The form of the generalized gradient approximation (GGA) proposed by Engel and Vosko (EVGGA) are used for the exchange and correlation potential. From the partial density of states, we find out that increasing the concentration of Bi results in a decrease of band gap of the compound. The PDOS of the InP compound elucidates that the valence bands are mainly comprised of P-p states, while the conduction band is mainly formed by foremost In-s and P-p with small contribution of P-s state while in InP/InB alloys the Bi-p stated strongly contribute in valance bands along with P-p states. From the calculated electronic structure we calculated the frequency dependent dielectric function along with other related optical constant. The transport coefficients are calculated using the semiclassical Boltzmann theory, as a function of temperature assuming a constant relaxation time. The Seebeck coefficient tended to decrease with increasing Bi content, whereas at low temperature figure of merit decreases with increasing the concentration of Bi.     

Numerical simulation of charge collection in two- and three-dimensional silicon diodes—a comparison

The charge collection transient following the strike of a silicon diode junction by an ionizing particle is computed in two and three dimensions for related device structures. The results of the computations are compared, and new physical interpretations of the results are discussed. The results indicate that although two and three dimensional simulations yield qualitatively similar behavior, accurate determination of the magnitude and duration of the current pulse and charge collection require three dimensional simulation. The present study also shows that, even for the simple structure considered, the device structure exerts an influence on the spreading of the disturbance, and this spreading is not, in general, axisymmetric.     

A new era in HVDC?

The authors review the advantages of high-voltage DC transmission, and discuss the benefits that the use of voltage-sourced converters could bring. They start by giving a simple representation of an HVDC interconnection and then discuss the use and benefits of HVDC for bulk power transmission, power transmission via cables, termination between unsynchronised AC systems, parallel AC/DC transmission, and minimising short circuit capacity increases. New power semiconductor devices for HVDC are discussed, in particular, the voltage source converter and its applications in HVDC for rotating machines and reactive power control     

An in-situ numerical–experimental approach for fatigue delamination characterization in microelectronic packages

An in-situ and cost-effective numerical–experimental approach for fatigue characterization of bi-material interfaces in microelectronic packages is presented. In this method using a sample-centered approach, a miniaturized sub-critical bending (MSCB) test setup is designed and fabricated based on the samples that are acquired directly from the production-line. Sub-critical crack growth (SCCG) is captured along the surface between molding compound (MC) and copper lead-frame (LF) in the samples prepared from Thin Quad Flat Package (TQFP). The toughness values such as critical (G_c) and sub-critical strain energy release rate (G_th) are measured. It is shown that crack propagation along the MC/LF interface is highly fatigue sensitive. In addition, fatigue–fracture tests under different isothermal conditions reveal that, the toughness values are higher in lower temperatures. The fractographical study of samples shows that, although some of the molding compound particles are left on the LF surface, the interfacial fracture is the dominant failure mode.     

Theoretical Analysis and Simulation of BJFET Obstructive Characteristics

A new bipolar junction field-effect transistor (BJFET) was described. The theoretical analysis and computer simulation of BJFET obstructive characteristic are achieved. The gate bias voltage affects the BJFET obstructive voltage greatly. The BJFET obstructive characteristic is relevant to structure parameters of channel width W and channel length L. The decrease-bias-voltage operation can weaken the device obstructive characteristic. The forward turn in device forward obstructive region can also affect the BJFET obstructive characteristic. BJFET has a good high temperature obstructive characteristic and can be applying to high temperature status as high voltage switch devices.     

Feasibility and modelling for convergence of optical-wireless network – A review

Now a days, the convergence of wireless and optical network gaining popularity to enhance the data carrying capacity, QoS and to support future multimedia applications. The queue theory plays an important role for analytically evaluating such converged networks. In the everyday state of affairs, queue phenomena are observed in the several situations like the health clinic, railway reservation system, automobile laundry centre, bank cash counter, call centre, etc. Similarly, the phenomenon of congestion is ascertained in the telephone network, computer network, communication systems and the Internet wherever nonstop enhancements need to be created to stay up with the quickly growing demand. The subsistence of these adverse clogging effects has lead toward the improvement of queuing theory-based statistical models. Therefore, these queues based statistical models answering to optimising queries corresponding to the way for assigning resources in converged optical and wireless networks. During this paper, a review on the role of the queuing model in wireless & optical communication is presented that concentrate on the present and future aspects of research.     

Times Square – Marriage of Real-Time and Logical-Time in GALS and Synchronous Languages

In this paper we introduce exact and non-exact real-time waits in the reactive Globally Asynchronous Locally Synchronous (GALS) programming languages and synchronous languages as their subset. The language constructs that allow use of real-time waits are illustrated on the SystemJ GALS language. They allow system designers to explicitly use, at the specification level, not only logical time but also real-time in order to control program execution. We transform the real-time constructs into a logical model of time, and statically bound the amount of delay introduced by these constructs. In addition, the introduced concepts utilize execution platforms that allow finding best and worst reaction time of a GALS or synchronous program.