Moisture diffusion modeling – A critical review

Techniques for enforcing the continuity of solute field in heterogeneous solvent under the conditions of steady temperature-humidity, steady temperature but dynamic humidity, and dynamic temperature are reviewed. The continuity of the wetness technique is justified on the principle of equality of chemical potential. The partial pressure technique is one of the many possible forms of pseudo techniques that can be derived from the wetness technique. The direct concentration technique is fundamentally flaw. The peridynamic technique in its original form is restricted to homogeneous solvent. The saturated concentration of solute in solvents decreases with increasing temperature; the rate of change with temperature differs between solvents and this leads to discontinuity of wetness along the interface of solvents. Continuity of wetness at the interface may be enforced using the intervention technique, the internal source technique, or the explicit finite difference scheme. These three techniques have been mutually validated in a reported study.     

Uncertainty quantification in nanowire growth modeling – A precursor to quality semiconductor nanomanufacturing

Mitigating the uncertainties associated with nanowire growth models have significant ramifications for the quality and reliability of nanomanufacturing of semiconductor nanowires. This research is focused on the development of a sectional-based mechanistic model of nanowire growth and the determination of the level of impacts the model parameters have on the growth of nanowires, characterized in terms of their weight, diameter and length. After testing the model with experimental growth data of silica (Si) nanowire weight, ZnO average diameter and length, it was observed that the direct top impingement growth coefficient (α_im) had the largest influence on the nanowire growth, in comparison to other model parameters → sidewall diffusion growth coefficient (α_sw), maximum allowable growth weight or length (W^(max)) and initial weight or length (W₀). The knowledge of the impact of uncertainty in these parameters on the overall growth of the nanowire can be leveraged on for robust design of the nanofabrication process that will impact on the quality, reliability, yield and cost of nanomanufacturing.     

On advance towards sub-sampling technique in phase locked loops – A review

This paper presents a symmetric review of academic and accomplished research endeavors in the field of Sub-Sampling Phase Locked Loop (SSPLL) design. Adequate emphasis has been given to understand the yearn for development of Sub-Sampling PLLs. Techniques that have emerged over the recent few years in context of better FOM, Jitter and Phase Noise reduction while maintaining extraordinary circuit performance in Sub-Sampling PLLs with CMOS/VLSI technology, have been captured in this paper. Consecutively, the main inspiration of this study is to present an overview of the PLL fundamentals, furtherance from analog to Digital PLL and various noises encountered in the different PLL components, important for the reader to have a better understanding about the design and analysis of Sub-Sampling PLLs.     

Compact failure modeling for devices subject to electrostatic discharge stresses – A review pertinent to CMOS reliability simulation

This paper reviews the physical mechanisms and compact modeling approaches of two physical damages in MOS devices induced by electrostatic discharge (ESD) stresses; namely gate oxide breakdown and thermal failures. Theories underlying the failure mechanism are discussed and compact models that can be used to monitor ESD induced gate oxide breakdown and thermal failure are developed. Related work reported in the literature is discussed, and benchmarking of measurement data versus simulation results are included in support of the modeling work.     

Experimental modeling of hysteresis in stage systems: A Maxwell–Iwan approach

Dynamic links of high-precision stage systems consist of wires and hoses that are used for example to transport electrical current to the actuators and sensors or cooling liquids to the stages. During stage motion, these dynamic links typically express complex hysteretic behavior due to internal friction and viscoelastic properties. As such, dynamic links give rise to unwanted disturbances acting on the high-precision stage systems. This paper presents a simple but accurate physics-based and experimental modeling procedure. The generalized Maxwell model and a modification of the Iwan model are combined in parallel to capture both frequency dependencies by viscoelastic effects and amplitude dependencies by friction-based effects. The modified and physically meaningful Iwan model is shown to be equivalent to the well-known Bouc–Wen model. A so-called normalized dissipation factor is introduced to quickly recognize frequency and/or amplitude dependent behavior using measured data. Using this information, a well-founded choice for an (initial) model structure to be identified can be made. Subsequently, an identification procedure is proposed to estimate values of the model parameters again using the measured data. A simulated experiment is used to show the use of the normalized dissipation factor and validate the identification procedure. Finally, the validity and usefulness of the Maxwell–Iwan modeling approach is demonstrated by experimental results obtained from an industrial wafer stage system.     

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 model and framework for human–environment interaction

This paper describes our approach for studying and prototyping human–environment interaction (HEI) within a pervasive space applied to ambient assistive living context. The objective of our approach consists in developing and implementing an HEI framework to modelling the human–machine interaction. This framework allows a customization facility for designers, developers and even end-users in defining and processing multimodal interaction. We underline the fact that the design of interaction for users with special needs do not have to be considered as orthogonal to the application but rather as a validation context which is the heart of our research laboratory activities. We have integrated our framework in demonstrator dedicated to people with disabilities to validate the concept. This paper will present the framework, the developed components of our HEI model and the prototype realised. The outcome of this research activity is to provide a multimodal processing framework to favour natural human pervasive environment by decreasing the cognitive workload necessary in a complex environment. Thus, this will contribute to achieve ubiquitous accessible space.     

The dipole–dipole interaction in photonic quantum wires

Numerical simulations are performed on the absorption coefficient in photonic quantum wires in the presence of the dipole–dipole interaction (DDI). The quantum wire is made from the two photonic crystals A and B where A is embedded in B. The probe and pump laser fields are applied to study the absorption process. Nanoparticles are not only interacting with each other via the DDI but also interacting with bound photon states of the wire. It is found that in the absence of the DDI the spectrum has two peaks and two minima. However, in the presence of the DDI the two peaks shift to the left of the zero detuning but the position of the minima does not change. These properties can be used to make new types of optoelectronic 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.     

Cloud service performance evaluation: status,challenges, and opportunities – a survey from the system modeling perspective

With rapid advancement of Cloud computing and networking technologies, a wide spectrum of Cloud services have been developed by various providers and utilized by numerous organizations as indispensable ingredients of their information systems. Cloud service performance has a significant impact on performance of the future information infrastructure. Thorough evaluation on Cloud service performance is crucial and beneficial to both service providers and consumers; thus forming an active research area. Some key technologies for Cloud computing, such as virtualization and the Service-Oriented Architecture (SOA), bring in special challenges to service performance evaluation. A tremendous amount of effort has been put by the research community to address these challenges and exciting progress has been made. Among the work on Cloud performance analysis, evaluation approaches developed with a system modeling perspective play an important role. However, related works have been reported in different sections of the literature; thus lacking a big picture that shows the latest status of this area. The objectives of this article is to present a survey that reflects the state of the art of Cloud service performance evaluation from the system modeling perspective. This articles also examines open issues and challenges to the surveyed evaluation approaches and identifies possible opportunities for future research in this important field.     

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.     

A hand gesture recognition technique for human–computer interaction

We propose an approach to recognize trajectory-based dynamic hand gestures in real time for human–computer interaction (HCI). We also introduce a fast learning mechanism that does not require extensive training data to teach gestures to the system. We use a six-degrees-of-freedom position tracker to collect trajectory data and represent gestures as an ordered sequence of directional movements in 2D. In the learning phase, sample gesture data is filtered and processed to create gesture recognizers, which are basically finite-state machine sequence recognizers. We achieve online gesture recognition by these recognizers without needing to specify gesture start and end positions. The results of the conducted user study show that the proposed method is very promising in terms of gesture detection and recognition performance (73% accuracy) in a stream of motion. Additionally, the assessment of the user attitude survey denotes that the gestural interface is very useful and satisfactory. One of the novel parts of the proposed approach is that it gives users the freedom to create gesture commands according to their preferences for selected tasks. Thus, the presented gesture recognition approach makes the HCI process more intuitive and user specific.     

Amplifying of surface plasmon-polariton in a metal–gain medium–vacuum structure

Propagation of a surface plasmon-polariton in a three-layer system consisting of the half-space filled with a metal, a layer of the gain medium of a finite thickness, and a half-space filled with vacuum is considered. The existence of the optimum thickness of the amplifying layer at which the plasmon is amplified several times stronger than in the case of infinite thickness is demonstrated. In particular, the plasmon loss can be compensated at a lower pumping intensity than in the case of infinite thickness of the gain layer.     

Brain–computer interface: The next frontier of telemedicine in human–computer interaction

The study proposes a novel brain–computer interface scheme for the next frontier of telemedicine in human–computer interaction, where the goal is to improve the interactions between users and computers in telemedicine. The system consists of discriminative area selection, feature extraction and classification. Discriminative area selection is proposed to obtain the optimal discriminative area, which can decrease the time length of event-related area to achieve more efficient computation and higher accuracy. A fuzzy Hopfield neural network is used to classify the features extracted by means of wavelet-fractal approach. Experimental results show that the proposed system is robust and performs better than several previous methods. It is also suggested being suitable for the applications of telemedicine in human–computer interaction.     

The privacy paradox – Investigating discrepancies between expressed privacy concerns and actual online behavior – A systematic literature review

Also known as the privacy paradox, recent research on online behavior has revealed discrepancies between user attitude and their actual behavior. More specifically: While users claim to be very concerned about their privacy, they nevertheless undertake very little to protect their personal data. This systematic literature review explores the different theories on the phenomenon known as the privacy paradox.Drawing on a sample of 32 full papers that explore 35 theories in total, we determined that a user’s decision-making process as it pertains to the willingness to divulge privacy information is generally driven by two considerations: (1) risk-benefit evaluation and (2) risk assessment deemed be none or negligible. By classifying in accordance with these two considerations, we have compiled a comprehensive model using all the variables mentioned in the discussed papers. The overall findings of the systematic literature review will investigate the nature of decision-making (rational vs. irrational) and the context in which the privacy paradox takes place, with a special focus on mobile computing. Furthermore, possible solutions and research limitation issues will be discussed.     

The More,the Better–Recent Advances in Construction of 2D Multi-Heterostructures

The past few years have witnessed significant development in the controlled growth of 2D heterostructures. Among those kinds of heterostructures, vertical and lateral ones have drawn the most attention. Vertical heterostructures can be created in the mode of layer by layer. The layer number and sequence in the vertical orientation can be modulated and thus leading to customized properties. However, the fabrication of lateral heterostructures has been met with challenges. The most concerning issue is related to the consistency at the atomic scale when two layers are stitched in a lateral direction. Adhering to the concept of epitaxial growth, chemical vapor deposition (CVD) has exerted significant impact in forming 2D lateral heterostructures. In this review, recent academic breakthroughs involving controlled growth of multi-heterostructures by CVD are present. The CVD technique in terms of growth parameters, choice of catalysts, and mechanism is fully emphasized, offering guidelines for shaping novel 2D heterostructures. Several novel multi-heterostructures attained by the CVD method are exhibited. Further, the properties and devices are described to demonstrate the unique features of multi-heterostructures. The great advances in precisely constructing multi-heterostructure are expected to push forward the way for 2D materials to industrialization and commercialization.     

Recent progress in epitaxial growth of III–V quantum-dot lasers on silicon substrate

In the past few decades, numerous high-performance silicon (Si) photonic devices have been demonstrated. Si, as a photonic platform, has received renewed interest in recent years. Efficient Si-based III–V quantum-dot (QDs) lasers have long been a goal for semiconductor scientists because of the incomparable optical properties of III–V compounds. Although the material dissimilarity between III–V material and Si hindered the development of monolithic integrations for over 30 years, considerable breakthroughs happened in the 2000s. In this paper, we review recent progress in the epitaxial growth of various III–V QD lasers on both offcut Si substrate and on-axis Si (001) substrate. In addition, the fundamental challenges in monolithic growth will be explained together with the superior characteristics of QDs.     

A new worm propagation threat in BitTorrent: modeling and analysis

Peer-to-peer (P2P) networking technology has gained popularity as an efficient mechanism for users to obtain free services without the need for centralized servers. Protecting these networks from intruders and attackers is a real challenge. One of the constant threats on P2P networks is the propagation of active worms. Recent events show that active worms can spread automatically and flood the Internet in a very short period of time. Therefore, P2P systems can be a potential vehicle for active worms to achieve fast worm propagation in the Internet. Nowadays, BitTorrent is becoming more and more popular, mainly due its fair load distribution mechanism. Unfortunately, BitTorrent is particularly vulnerable to topology aware active worms. In this paper we analyze the impact of a new worm propagation threat on BitTorrent. We identify the BitTorrent vulnerabilities it exploits, the characteristics that accelerate and decelerate its propagation, and develop a mathematical model of their propagation. We also provide numerical analysis results. This will help the design of efficient detection and containment systems.     

Isolated large π systems in pyrene–fluorene derivatives for intramolecular through-space interaction in organic semiconductors

In order to give an insight of the special spectra of isolated π systems, a series of pyrene–fluorene derivatives, with conjugated or non-conjugated pyrene groups, were systematically studied. Besides absorption of non-conjugated pyrene itself and main conjugation chain, all the pyrene-non-conjugated large conjugated materials show a characteristic sharp absorption peak at ～352 nm. Through systematical investigation, this special absorption peak was attributed to the intramolecular through-space interaction between the two isolated large π systems. Such interaction could also be defined as π – π hyperconjugation. And from quantum calculation, this intramolecular interaction does shorten the length of single bond. Through systematical research, the condition of this intramolecular through-space interaction is proved to be that the non-conjugated pyrene must have projection on fluorene plane. And then this effect is applied to explain the improved injection ability of the materials by bringing out one simple hopping model.