Internet of Things for the Future of Smart Agriculture: A Comprehensive Survey of Emerging Technologies

This paper presents a comprehensive review of emerging technologies for the internet of things (IoT)-based smart agriculture. We begin by summarizing the existing surveys and describing emergent technologies for the agricultural IoT, such as unmanned aerial vehicles, wireless technologies, open-source IoT platforms, software defined networking (SDN), network function virtualization (NFV) technologies, cloud/fog computing, and middleware platforms. We also provide a classification of IoT applications for smart agriculture into seven categories: including smart monitoring, smart water management, agrochemicals applications, disease management, smart harvesting, supply chain management, and smart agricultural practices. Moreover, we provide a taxonomy and a side-by-side comparison of the state-of-the-art methods toward supply chain management based on the blockchain technology for agricultural IoTs. Furthermore, we present real projects that use most of the aforementioned technologies, which demonstrate their great performance in the field of smart agriculture. Finally, we highlight open research challenges and discuss possible future research directions for agricultural IoTs.      

Integrated analysis and design in stochastic optimization

An integrated analysis and design approach for stochastic optimization of structures is presented. The proposed procedure employs a first order second moment (FOSM) method for evaluating the constraints associated with structural safety.Two variants of the new approach are presented. The idea is to integrate the nested iterative procedures for constraint evaluation and optimum search into one. The new approach is applied to simple design examples. The results are compared to those obtained by classical stochastic optimization using the FOSM method to evaluate the constraints. Both methods are robust to a satisfactory degree and substantially reduce the computational effort.     

Influence of ground and corona currents on dielectric behavior of small air gaps

This paper investigates the influence of grounding on the field distribution and on the dielectric behavior of small rod-plate and rod-rod air gaps. This effect can be attributed to the grounding of one electrode. In the different arrangements with one electrode grounded or with the electrodes symmetrically charged the experimental results of the corona and breakdown are recorded and compared to the simulation results of the field distribution. It is resulted that the grounding influences significantly the electric field distribution, the dc corona and the dc breakdown. The field is less inhomogeneous in grounded rod - plate air gaps and in rod-rod air gaps with symmetrically charged electrodes, and consequently the values of the corona onset and the breakdown voltage are higher. In longer air gaps the corona current influences the field distribution and consequently the dc breakdown. The effect of grounding on the breakdown is weakened when the dc polarity of the voltage is negative, otherwise it is enhanced. In air gaps with lengths > 3 cm (negative dc polarity) or >8 cm (positive dc polarity) it is overlapped by the effect of the corona current. Relations between the field strength, the corona current, the corona onset and the breakdown voltage arise. The principle of action-reaction is valid.     

Authentication schemes for smart mobile devices: threat models,countermeasures, and open research issues

Telecommunication Systems - This paper presents a comprehensive investigation of authentication schemes for smart mobile devices. We start by providing an overview of existing survey articles...     

Comparison of probabilistic and deterministic optimizations using genetic algorithms

This paper describes an application of genetic algorithms to deterministic and probabilistic (reliability-based) optimization of damping augmentation for a truss structure. The probabilistic formulation minimizes the probability of exceeding upper limits on the magnitude of the dynamic response of the structure due to uncertainties in the properties of the damping devices. The corresponding deterministic formulation maximizes a safety margin with respect to these limits. Because this work was done in the context of an experimental comparison of the reliabilities of the resulting designs, antioptimization was used to maximize the contrast between the probabilities of failure of the two designs. This contrast maximization was also performed with a genetic algorithm. The paper describes the genetic algorithm used for the optimization and antioptimization, and a number of modifications to the antioptimization formulation intended to reduce the computational expense to an acceptable level. Optimal designs are obtained for both formulations. The probabilistic design shows a very significant improvement in reliability.     

Large-eddy simulation of a turbulent jet and wake vortex interaction

In this study, temporal large-eddy simulations of the interaction between a turbulent jet flow and a trailing vortex are described. Three cases are analyzed: in the first one, the jet and the vortex axes are sufficiently well separated to not interact immediately, while in the second case, the distance between the jet and the vortex is reduced by half. In the last case the jet blows in the vortex core. In the two first cases, as the jet spreads it is progressively deflected by the continuous input of crossflow momentum. Thus it acquires azimuthal and radial components of velocity, causing the emergence of three-dimensional structures of azimuthal vorticity around it. When the jet and the vortex are superimposed, the turbulent kinetic energy does not increase, the vortex core is very buffeted. Numerical simulation results of the convection-diffusion of a passive scalar show that its distribution (initially in the jet) cannot penetrate inside the vortex core due to its solid rotation. For the cases where the jet is initially outside the vortex and when it is injected in the vortex wake, its value remains very high and cannot get out of the vortex core. This phenomenon confirms the existence of a stabilizing “dispersion buffer”, adjacent to the core, which prevents amplification of the turbulence generated inside the core.