Maximum Data Collection Rate in Rechargeable Wireless Sensor Networks with Multiple Sinks

In rechargeable wireless sensor networks, a sensor cannot be always benefi cial to conserve energy when a network can harvest excessive energy from the environment due to its energy replenished continually and limited energy storage capacity. Therefore, surplus energy of a node can be utilized for strengthening packet delivery efficiency and improving data collection rate. In this work, we propose an algorithm to compute an upper data generation rate that maximizes it as an optimization problem for a network with multiple sinks, which is formulated as a linear programming problem. Subsequently, a dual problem by introducing Lagrange multipliers is constructed, and subgradient algorithms are used to solve it in a distributed manner. The resulting algorithms are guaranteed to converge to an optimal data generation rate, which are illustrated by an example in which an optimum data generation rate is computed for a network of randomly distributed nodes. Through extensive simulation and experiments, we demonstrate our algorithm is efficient to maximize data collection rate in rechargeable wireless sensor networks.

Efficient direction-independent fog harvesting using a corona discharge device with a multi-electrode structure

Efflcient collection of water from fog can effectively alleviate the problem of water shortages in foggy but water-scarce areas,such as deserts,islands and so on.Unlike inefflcient fog meshes,corona discharge can charge water droplets and further enhance the water-collecting effect.This study proposes a novel multi-electrode collecting structure that can achieve efflcient and direction-independent water collection from fog.The multi-electrode structure consists of three parts:a charging electrode,an intercepting electrode and a ground electrode.Four types of watercollecting structures are compared experimentally,and the collection rates from a traditional fog mesh,a wire-mesh electrode with fog coming from a high-voltage electrode,a wire-mesh electrode with fog coming from a ground electrode and a multi-electrode structure are 2–3 g h^(-1),100–120 g h^(-1),60–80 g h^(-1)and 200–220 g h^(-1),respectively.The collection rate of the multielectrode structure is 100–150 times that of a traditional fog mesh and 2–4 times that of a wiremesh electrode.These results demonstrate the superiority of the multi-electrode structure in fog collection.In addition,the motion equation of charged droplets in an electric fleld is also derived,and the optimization strategy of electrode spacing is also discussed.This structure can be applied not only to fog collection,but also to air puriflcation,factory waste gas treatment and other flelds.

Experimental study on the sampling efficiency of the whirl type separation sand sampler in a wind tunnel

A performance test was conducted in a wind tunnel by changing the principal configuration parameters of a sampler such as the diameter of the container, inlet width and cone height. The results show that the average sand collection rate is from 80% to 90% when any one of the configuration parameter levels is changed. However, the variation of a parameter level results in different ef-fects on the sand collection rate for each soil sample within a certain size range of sand grains. The results show that for various sand grain sized soil sample at each wind speed, the sand collection rate decreases when the diameter of the container changes from 50 mm to 40 mm, the sand collection rate increases by about 2%-3% when the inlet width changes from 10 mm to 8 mm, and the sand collection rate increases by about 3%-4% when cone height is altered from 100 mm to 125 mm. The average sand collection rate is enhanced by 2%-4% for the soil sample of different sized sand grains when the diameter of the container is 50 mm, the inlet width is 8 mm, and cone height is 125 mm.

Experiment and optimal design of a collection device for a residual plastic film baler

It is imperative to carry out research on residual plastic film collection technology to solve the serious problem of farmland pollution.The residual plastic film baler was designed as a package for film strip collection,cleaning and baling.The collection device is a core component of the baler.Response surface analysis was used in this study to optimize the structure and working parameters for improving the collection efficiency of residual film and the impurity of film package.The results show that the factors affecting the collection rate of residual film and the impurity of the film package are the speed ratio(k)between the trash removal roller and eccentric collection mechanism,the number(z)and the mounting angle(θ)of spring teeth in the same revolution plane.For the collection rate,the importance of the three factors are in the order,k>z>θ.Meanwhile,for the impurity,the importance of three factors are in the order,z>k>θ.When the speed ratio,the mounting angle and the number of spring teeth was set at 1.6°,45°,and 8°,respectively,the collection rate of residual film was 88.9%and the impurity of residual film package was 14.2%for the baler.