Considering the internet of things (IoT), end nodes such as wireless sensor network, RFID and embedded systems are used in many applications. These end nodes are known as resource-constrained devices in the IoT network. These devices have limitations such as computing and communication power, memory capacity and power. Key pre-distribution schemes (KPSs) have been introduced as a lightweight solution to key distribution in these devices. Key pre-distribution is a special type of key agreement that aims to select keys called session keys in order to establish secure communication between devices. One of these design types is the using of combinatorial designs in key pre-distribution, which is a deterministic scheme in key pre-distribution and has been considered in recent years. In this paper, by introducing a key pre-distribution scheme of this type, we stated that the model introduced in the two benchmarks of KPSs comparability had full connectivity and scalability among the designs introduced in recent years. Also, in recent years, among the combinatorial design-based key pre-distribution schemes, in order to increase resiliency as another criterion for comparing KPSs, attempts were made to include changes in combinatorial designs or they combine them with random key pre-distribution schemes and hybrid schemes were introduced that would significantly reduce the design connectivity. In this paper, using theoretical analysis and maintaining full connectivity, we showed that the strength of the proposed design was better than the similar designs while maintaining higher scalability.
Electrochemical impedance spectroscopy (EIS), anodic polarization and scanning electron microscopy techniques were used to investigate the damage mechanism in the transpassive potential region of AISI ... 相似文献
In this article, we study a linear array of bowtie nanoantennas placed between two metallic strips that can work from 800 to 1420 nm (600 nm linewidth), with an electric field enhancement factor close to 20. We study the dynamical change of the position of the electric field enhancement amongst different elements in the array and, at the same time, the effects of dispersion on the scalability of the array elements. A systematic analysis and methodology to produce an array that can operate over a large bandwidth whilst maintaining the electric field enhancement without significant variation is provided. 相似文献
The early twentieth-century invention of the airplane brought on a cultural euphoria that influenced the works and writings of urbanists, architects, artists, and science-fiction writers during the 1920s and 1930s. Le Corbusier's urban design for Rio de Janeiro—which he sketched, so he claimed, from an airplane—offers a visual basis to study how the aesthetic experience of flight was translated spatially, visually, and politically into his design of the future city. The polemics informing Le Corbusier's aerial "discovery" of South American geography revealed that there was a new empowerment in the act of looking from above, and that the spatial characteristics of his subsequent design interventions evoked that empowerment. 相似文献
We compare the use of price-based policies or taxes, and quantity-based policies or quotas, for controlling emissions in a dynamic setup when the regulator faces two sources of uncertainty: (i) market-related uncertainty; and (ii) ecological uncertainty. We assume that the regulator is a rational Bayesian learner and the regulator and firms have asymmetric information. In our model the structure of Bayesian learning is general. Our results suggest that the expected level of emissions is the same under taxes and quotas. However, the comparison of the total benefits related to these policies suggests that taxes dominate quotas, that is, they provide a higher social welfare. Even though taxes have some benefits over quotas, neither learning nor ecological uncertainty affect the choice of policy, i.e., the only factor having such an impact is uncertainty in the instantaneous net emissions benefits (market-related uncertainty). Besides, the more volatile is this uncertainty, the more benefits of taxes over quotas. Ecological uncertainty leads to a difference between the emissions rule under the informed and the rational learning assumptions. However, the direction of this difference depends on the beliefs bias with regard to ecological uncertainty. We also find that a change in the regulator’s beliefs toward more optimistic views will increase the emissions. 相似文献
Microsystem Technologies - In this paper, free vibration analysis of a double viscoelastic nano-composite plate system reinforced by functionally graded single-walled carbon nanotubes (FG-SWCNT)... 相似文献
Understanding the flow fields at the micro-scale is key to developing methods of successfully mixing fluids for micro-scale applications. This paper investigates flow characteristics and mixing efficiency of three different geometries in micro-channels. The geometries of these channels were rectangular with a dimension of; 300 μm wide, 100 μm deep and 50 mm long. In first channel there was no obstacle and in the second channel there were rectangular blocks of dimension 300 μm long and 150 μm wide are placed in the flow fields with every 300 μm distance attaching along the channel wall. In the third geometry, there were 100 μm wide fins with 150° angle which were placed at a distance of 500 μm apart from each other attached with the wall along the 50 mm channel. Fluent software of Computational Fluid Dynamics (CFD) was used to investigate the flow characteristics within these microfluidic model for three different geometries. A species 2D model was created for three geometries and simulations were run in order to investigate the mixing behaviour of two different fluid with viscosity of water (1 mPa s). Models were only built to investigate the effect of geometry, therefore only one fluid with similar viscosity was used in these models. Velocity vector plots were used in the CFD analysis to visualise the fluid flow path. Mass fractions of fluid were used to analyse the mixing efficiency. Two different colours for water were used to simulate the effect of two different fluids. The results showed that the mixing behaviour strongly depended on the channel geometry when other parameters such as fluid inlet velocity, viscosity and pressure of fluids were kept constant. In two geometries lateral pressure and swirling vortexes were developed which provided better mixing results. Creation of swirling vortexes increased diffusion gradients which enhanced diffusive mixing. 相似文献
The characterization of an optical sensor membrane is described for simultaneous determination of sulfite and sulfide ions based on the immobilization of crystal violet on a triacetylcellulose membrane. The absorbance of the membranes decreased by increasing sulfite and sulfide concentration. The partial least squares (PLS-1) calibration model based on spectrophotometric measurement for simultaneous determination of sulfite and sulfide ions was applied. This method is based on the difference between the rate of the reaction of sulfide and sulfite with membranes in pH 7.0 buffer solution and at 25 °C. The experimental calibration matrix for partial least squares (PLS-1) calibration was designed with 18 samples. The cross-validation method was used for selecting the number of factors. The results showed that simultaneous determination could be performed in the range of 200–2000 μg mL−1 (2.5–25 mmol L−1) and 80–900 μg mL−1 (2.5–28.125 mmol L−1) for sulfite and sulfide, respectively. The sensor can readily be regenerated with water and the color is fully reversible. The sensor was successfully applied to the simultaneous determination of sulfide and sulfite in water samples. 相似文献
ABSTRACT Water is one of the top priority item s i relief activities but the appropriateness and effectiveness of this activity may be questioned. Water and sanitation (WS) are inseparable and together they play major roles in the transmission of the pathogen of diarrhoeal disease. Thousands of people die or suffer from WS-related diseases during postdisaster periods. Here we present WS-related experiences gained after Bangladesh's 1991 cyclone and the views of participants in a regional and a national (local) workshop on this matter held in Bangladesh. About 63 per cent of the water purifying tablets (WPTs) distributed after the 1991 cyclone were found to have lost potency Relief personnel lack basic knowledge about WS practices and the management of WS provision. Participants in the two workshops documented serious problems i this field at both regional and national levels. Major issues for research may include: an appropriate environmental preparedness plan; appropriate waste disposal technologies; appropriate water treatment methods; self- help activities during vulnerable periods; and health education related to WS in disaster situations. 相似文献