Evaluation of the spray generated by a greenhouse spraying robot

 In this study, characterization of an automatic greenhouse spraying system containing a full cone spray nozzle is presented.  Spray flow rate of the nozzle as a function of incoming pressure to the nozzle, together with distribution of mean drop size, two components of drop velocity and uniformity of the generated spray are given in this study.  Based on the results obtained, mean droplet size at the centreline of the spray is much smaller than dose in the outer side of the full cone spray.  Uniformity of the generated spray by a given nozzle should be examined before application, especially if the nozzle is not new.  The average generated drop size by the examined nozzle is less than 60 μm which is suitable for the insecticide or fungicide applications.   Keywords: spray, nozzle, full-cone nozzle, insecticide, uniformit

Robust Privacy-Utility Tradeoffs Under Differential Privacy and Hamming Distortion

A privacy-utility tradeoff is developed for an arbitrary set of finite-alphabet source distributions. Privacy is quantified using differential privacy (DP), and utility is quantified using expected Hamming distortion maximized over the set of distributions. The family of source distribution sets (source sets) is categorized into three classes, based on different levels of prior knowledge they capture. For source sets whose convex hull includes the uniform distribution, symmetric DP mechanisms are optimal. For source sets whose probability values have a fixed monotonic ordering, asymmetric DP mechanisms are optimal. For all other source sets, general upper and lower bounds on the optimal privacy leakage are developed and necessary and sufficient conditions for tightness are established. Differentially private leakage is an upper bound on mutual information leakage: the two criteria are compared analytically and numerically to illustrate the effect of adopting a stronger privacy criterion

Robust Privacy-Utility Tradeoffs Under Differential Privacy and Hamming Distortion

A privacy-utility tradeoff is developed for an arbitrary set of finite-alphabet source distributions. Privacy is quantified using differential privacy (DP), and utility is quantified using expected Hamming distortion maximized over the set of distributions. The family of source distribution sets (source sets) is categorized into three classes, based on different levels of prior knowledge they capture. For source sets whose convex hull includes the uniform distribution, symmetric DP mechanisms are optimal. For source sets whose probability values have a fixed monotonic ordering, asymmetric DP mechanisms are optimal. For all other source sets, general upper and lower bounds on the optimal privacy leakage are developed and necessary and sufficient conditions for tightness are established. Differentially private leakage is an upper bound on mutual information leakage: the two criteria are compared analytically and numerically to illustrate the effect of adopting a stronger privacy criterion

Influence of tillage depth, penetration angle and forward speed on the soil/thin-blade interaction force

In this study, an experimental investigation regarding the influence of three independent variables including tillage depth (10, 15, 20 cm), angle of attack (60, 75, 90 degrees) and forward speed (0.5, 1, 1.35, 1.7 m/s) on draft force of a thin blade is presented.  Chisel plow in this research was constructed in two furrows with a blade width of 3 cm and a maximum depth of 25 cm (the distance between two blades was 1 m).  Some changes were made in the chassis of the chisel plow in order to obtain different attack angle of the blade.  The experimental work was then complemented with a new theoretical model for predicting the blade force using dimensional analysis method.  The final expression for estimating the pull resistance is as a function of several soil engineering properties (soil bulk density, soil adhesion and cohesion coefficients), blade parameters (blade width and blade rake angle) and operational conditions (tillage depth and forward speed).  Finally constants of the model were computed based on obtained experimental data.  The proposed model properly estimated the draft force of a thin blade.  Results obtained in this study indicate the stronger influence of tillage depth on the pulling force of a thin soil-working blade compared to the penetration angle and forward velocity.  The average error for the vertical blade with depth of 20, 15 and 10 cm were obtained equal to 4.5%, 4% and 1.5%, respectively.   Keywords: tillage, thin blade, chisel plow, interaction force, dimensional analysi

Influence of different tempering period and vacuum conditions on the rice grain breakage in a thin layer dryer

Drying and milling of the paddy are known as the most important process influencing the rice grain breakage. Therefore in this study, influence of tempering period and the reduced atmospheric pressure (vacuum) on the crack formation of two rice varieties (Nemat and Pajouhesh) during the tempering stage is presented. Four different level of drying temperature (40, 50, 60 and 70°C) were used in this study. After drying, paddies have been transferred to a vacuum chamber ranging from 0.4 at to 1 atm (ambient pressure). Based on the results obtained in this study, crack formation in rice grains increases with increasing drying time and drying temperature. In contrast, a reduced pressure during the relaxation stage significantly reduced the rice grain breakage. During the relaxation period in the vacuum chamber, heat transfer within the rice grain occurs slowly, yields minimizing the thermal and moisture stresses. The optimized combination of temperature, time, and pressure for the Nemat and Pajouhesh rice varieties obtained 60°C, 5 hr, and 0.8 atm, respectively

Evaluating the Catalytic Performance of La1-xCexNi1-yZnyO3 Nanostructure Perovskites in the Carbon Dioxide Reforming of Methane

AbstractIn this research nanostructure perovskites La1-xCexNi1-yZnyO3 were prepared by sol-gel auto-combustion method and their application were evaluated for methane reforming with carbon dioxide and syngas production. Catalysts were designed by Response Surface Method (RSM) based on central composite design (CCD) with three factors of catalyst characteristics, x, y and Tc. The prepared catalysts were examined in methane reforming process at 750 ˚C temperature and atmospheric pressure. Analysis of variance (ANOVA) showed that parameters don’t have any linear effect on catalytic activity and their effect is proportional to square form. Among this investigated parameters, Ni content effect is considerable and calcination temperature (Tc) has a partial effect. In this research R2 value was 94.88%. The optimum catalyst which determined by RSM was La0.60Ce0.40Ni0.81Zn0.19O3 in 747 ˚C calcination temperature that corresponds to empirical result. The XRD characterization of optimum catalyst showed that perovskite catalyst was formed in rhombohedra phase with nanostructure crystals and the SEM of optimum catalyst confirmed the nano scale of prepared particles

Arctic wetland system dynamics under climate warming

Warming and hydrological changes have already affected and shifted environments in the Arctic. Arctic wetlands are complex systems of coupled hydrological, ecological, and permafrost-related processes, vulnerable to such environmental changes. This review uses a systems perspective approach to synthesize and elucidate the various interlinked responses and feedbacks of Arctic wetlands to hydroclimatic changes. Starting from increased air temperatures, subsequent permafrost thaw and concurrent hydrological changes are identified as key factors for both shrinkage and expansion of wetland area. Other diverse factors further interact with warming, hydrological changes, and permafrost thaw in altering the Arctic wetland systems. Surface albedo shifts driven by land cover alterations are powerful in reinforcing Arctic warming, while vegetation-related factors can balance and decelerate permafrost thaw, causing negative feedback loops. With the vast amounts of carbon stored in Arctic wetlands, their changes in turn affect the global carbon cycle. Overall, the systems perspectives outlined and highlighted in this review can be useful in structuring and elucidating the interactions of wetlands with climate, hydrological, and other environmental changes in the Arctic, including the essential permafrost-carbon feedback. This article is categorized under: Water and Life > Nature of Freshwater Ecosystems Water and Life > Stresses and Pressures on Ecosystems Science of Water > Water and Environmental Change

A New Solution to the Relative Orientation Problem using only 3 Points and the Vertical Direction

This paper presents a new method to recover the relative pose between two images, using three points and the vertical direction information. The vertical direction can be determined in two ways: 1- using direct physical measurement like IMU (inertial measurement unit), 2- using vertical vanishing point. This knowledge of the vertical direction solves 2 unknowns among the 3 parameters of the relative rotation, so that only 3 homologous points are requested to position a couple of images. Rewriting the coplanarity equations leads to a simpler solution. The remaining unknowns resolution is performed by an algebraic method using Grobner bases. The elements necessary to build a specific algebraic solver are given in this paper, allowing for a real-time implementation. The results on real and synthetic data show the efficiency of this method