A survey on developing publish/subscribe middleware over wireless sensor/actuator networks

Publish/subscribe (Pub/Sub) interaction paradigm is receiving more attention in commercial and academic research nowadays. It is an effective interaction scheme for large-scale distributed systems due to its ability of decoupling communicating entities in time, space, and synchronization. The decoupling properties are well-suited for Wireless Sensor Network (WSN) applications because of their special characteristics such as data-centricity, dynamicity, and many-to-many communications. Many studies have been conducted to adapt Pub/Sub communication model to WSN. In this paper, we review the Pub/Sub interaction paradigm in the context of WSN. Moreover, we classify, analyze and synthesize different Pub/Sub based solutions proposed recently for WSN and discuss the open problems and new research directions in this area. Also, we propose a new reference model for pub/sub middleware in wireless sensor and actuator networks. To the best of our knowledge this is the first survey on this specific subject.     

Three‐dimensional remeshed smoothed particle hydrodynamics for the simulation of isotropic turbulence

We present a remeshed particle‐mesh method for the simulation of three‐dimensional compressible turbulent flow. The method is related to the meshfree smoothed particle hydrodynamics method, but the present method introduces a mesh for efficient calculation of the pressure gradient, and laminar and turbulent diffusion. In addition, the mesh is used to remesh (reorganise uniformly) the particles to ensure a regular particle distribution and convergence of the method. The accuracy of the presented methodology is tested for a number of benchmark problems involving two‐ and three‐dimensional Taylor‐Green flow, thin double shear layer, and three‐dimensional isotropic turbulence. Two models were implemented, direct numerical simulations, and Smagorinsky model. Taking advantage of the Lagrangian advection, and the finite difference efficiency, the method is capable of providing quality simulations while maintaining its robustness and versatility.     

Ellipsometric configurations using a phase retarder and a rotating polarizer and analyzer at any speed ratio

In this paper,we propose an ellipsometer using a phase retarder and rotating polarizer and analyzer at a speed ratio 1:N.Different ellipsometric configurations are presented by assuming N = 1,2,and 3.Moreover,two values of the offset angle of the retarder are considered for each ellipsometric configuration.The Mueller formalism is employed to extract the Stokes parameters,from which the intensity received by the detector is obtained.The optical properties of c-Si are calculated using all configurations.A comparison between different configurations is carried out considering the effect of the noise on the results and the uncertainties in the ellipsometric parameters as functions of the uncertainties of the Fourier coefficients.It is found that the alignment of the phase retarder has a crucial impact on the results and the ellipsometric configuration with speed ratio 1:1 is preferred over the other configurations.     

Hybrid fiber-to-the-x and free space optics for high bandwidth access networks

The authors demonstrate an implementation of hybrid fiber-to-the-x (FTTx) and free space optical (FSO) technologies as another alternative solution to bring light-speed performance to the residential users. A simulation experiment was performed with a 20 km single-mode fiber spanning from the Central Office to 1:32 splitter, before the signal propagated through the air to FSO receivers which were individually equipped with an Optical Network Unit (ONU). A downstream performance of the video signal transmitted at 1550 nm wavelength with a bit rate of 1 Gbps was studied under different weather conditions. The results show that for an acceptable bit error rate of 10⁻⁹, 32 ONUs are supportable at a combined FSO: FTTx distance ratio of 20:4.8, 20:2, and 20:1.4 km during clear weather, average and heavy rain, respectively.     

Computational bridge aeroelasticity using turbulence models

Long-span bridges may collapse due to the interaction of turbulent wind flow and structural motion. The investigation of the fluid-structure interaction requires appropriate models for the structure, the wind flow and the coupling between them. Modeling and simulation of the wind flow is still a challenging aspect. The aim of this paper is to show the application of Reynolds Averaged Navier-Stokes (RANS) equations with a turbulence model in the context of bridge aeroelasticity. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

An Untargeted Metabolomics Approach for Correlating Pulse Crop Seed Coat Polyphenol Profiles with Antioxidant Capacity and Iron Chelation Ability

Pulse crop seed coats are a sustainable source of antioxidant polyphenols, but are typically treated as low-value products, partly because some polyphenols reduce iron bioavailability in humans. This study correlates antioxidant/iron chelation capabilities of diverse seed coat types from five major pulse crops (common bean, lentil, pea, chickpea and faba bean) with polyphenol composition using mass spectrometry. Untargeted metabolomics was used to identify key differences and a hierarchical analysis revealed that common beans had the most diverse polyphenol profiles among these pulse crops. The highest antioxidant capacities were found in seed coats of black bean and all tannin lentils, followed by maple pea, however, tannin lentils showed much lower iron chelation among these seed coats. Thus, tannin lentils are more desirable sources as natural antioxidants in food applications, whereas black bean and maple pea are more suitable sources for industrial applications. Regardless of pulse crop, proanthocyanidins were primary contributors to antioxidant capacity, and to a lesser extent, anthocyanins and flavan-3-ols, whereas glycosylated flavonols contributed minimally. Higher iron chelation was primarily attributed to proanthocyanidin composition, and also myricetin 3-O-glucoside in black bean. Seed coats having proanthocyanidins that are primarily prodelphinidins show higher iron chelation compared with those containing procyanidins and/or propelargonidins.     

Performance Analysis of Amplify-and-Forward Relay Systems with Interference-Limited Destination in Various Rician Fading Channels

In this paper, we investigate the performance of a dual-hop fixed-gain amplify-and-forward relay system in the presence of co-channel interference at the destination node. Different fading scenarios for the desired user and interferers’ channels are assumed in this study. We consider the Rician/Nakagami- \(m\) , the Rician/Rician, and the Nakagami- \(m\) /Rician fading environments. In our analysis, we derive accurate approximations for the outage probability and symbol error probability (SEP) of the considered scenarios. The generic independent non-identically distributed (i.n.d.) case of interferers’ channels is considered for the Rician/Nakagami- \(m\) scenario; whereas, the independent identically distributed (i.i.d.) case is studied for the Rician/Rician and the Nakagami- \(m\) /Rician environments. Furthermore, to get more insights on the considered systems, high signal-to-noise ratio (SNR) asymptotic analysis of the outage probability and SEP is derived for special cases of the considered fading scenarios. Monte-Carlo simulations and numerical examples are presented in order to validate the analytical and asymptotic results and to illustrate the effect of interference and other system parameters on the system performance. Results show that the different fading models of interferers’ channels have the same diversity order and that the interference degrades the system performance by only reducing the coding gain. Furthermore, findings show that the case where the fading parameter of the desired user first hop channel is better than that of the second hop gives better performance compared to the vise versa case, especially, at low SNR values; whereas, both cases almost behave the same at high SNR values where the performance of the system is dominated by the interference affecting the worst link. Finally, results show the big gap in system performance due to approximating the Rician fading distribution with the Nakagami- \(m\) distribution which is an indication on the inaccuracy of making such approximations in systems like the considered.     

Design and modeling of high-resolution multibit log-domain \Delta \Sigma modulators

Log-domain Delta-Sigma ( $\Delta \Sigma$ ) modulators are attractive for implementing analog-to-digital (A/D) converters (ADCs) targeting low-power low-voltage applications. Previously reported log-domain $\Delta \Sigma$ modulators were limited to 1-bit quantization and, hence, could not benefit from the advantages associated with multibit quantization (namely, reduced in-band quantization noise, and increased modulator stability). Unlike classical $\Delta \Sigma$ modulators, directly extending a log-domain $\Delta \Sigma$ modulator with a 1-bit quantizer to a log-domain $\Delta \Sigma$ modulator with a multibit quantizer is challenging, in terms of CMOS circuit implementation. Additionally, the realization of log-domain $\Delta \Sigma$ modulators targeting high-resolution applications necessitates minimization of distortion and noise in the log-domain loop-filter. This paper discusses the challenges of multibit quantization and digital-to-analog (D/A) conversion in the log-domain, and presents a novel multibit log-domain $\Delta \Sigma$ modulator, practical for CMOS implementation. SIMULINK models of log-domain $\Delta \Sigma$ modulator circuits are proposed, and the effects of various circuit non-idealities are investigated, including the effects of log-domain compression–expansion mismatch. Furthermore, this paper proposes novel low-distortion log-domain analog blocks suitable for high-resolution analog-to-digital (A/D) conversion applications. Circuit simulation results of a proposed third-order 3-bit class AB log-domain $\Delta \Sigma$ loop-filter demonstrate 10.4-bit signal-to-noise-and-distortion-ratio (SNDR) over a 10 kHz bandwidth with a $0.84\,V_{pp}$ differential signal input, while operating from a 0.8 V supply and consuming a total power of $35.5\,\upmu \hbox {W}.$      

Social acceptance of location-based mobile government services for emergency management

Location-based services deployed by governments can be used to assist people manage emergencies via their mobile handsets. Research delineating the acceptance of public services in the domain of emergency management has been scantly investigated in information systems. The main aim of this study is to assess the viability of location-based mobile emergency services by: (i) exploring the issues related to location-based services and their nationwide utilisation for emergency management; (ii) investigating the attitudinal and behavioural implications of the services; and (iii) examining the social acceptance or rejection of the services and identify the determinants of this acceptance or rejection. The results reveal that both attitude and perceived usefulness demonstrate a good prediction power of behavioural intention. Although perceived ease of use was found not to be a predictor of attitude, the results affirm its influence on perceived usefulness. The results also demonstrate the role of trust as the most influential determinant of individual perception of the usefulness of the services. Further, the results indicate that only the collection of personal location information, as a perceived privacy concern, had a significant negative impact on trust. Implications and future research are also discussed.