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Advances in Functional Differential Equations
Get PDFFunctional differential equations are omnipresent in mathematics and related sciences, varying from applications in engineering to medicine. Early systematic approaches to differential and difference equations as independent mathematical discipline appeared in early 1900. These early contributions are concerned with a linear theory and connections to functional equations. In recent years, problems in nonlinear science modeled by functional differential and difference equations have gained much interest, leading to extensive development in the theory of discrete and continuous dynamical systems. One reason for their popularity is that functional differential and difference equations provide realistic mathematical models. Indeed, over the past 30 years we have seen many fascinating research papers and monographs which address different applications in epidemic models, neural networks, artificial intelligence, robotics and many other disciplines. Mathematical models of COVID-19 modeled by difference, fractional, and delay differential equations played a vital role in understanding the dynamics of the disease and thus in “mitigating the curve” of infections. Thus, the theory of functional differential equations will be even more important in understanding different natural phenomena in the future. The special issue broadly deals with functional differential equations and presents the recent developments in the areas mentioned above. The guest editor believes that the papers published in this special issue will be helpful to a wide range of researchers and will motivate further research in the topics presented and in the related fields
Optimizing Conditions for the Measurement of Soil Inorganic Nitrogen with a Micro-Plate Reader
Get PDFThere are numerous methods for measuring inorganic nitrogen (N) in soils, but many of these are complex or require expensive equipment. In order to seek an accurate and rapid measurement method, we optimized the conditions for soil inorganic nitrogen (N) (NH4+-N and NO3–N) determination with a micro-plate reader; a systematic study was carried out. The effects of extraction regent concentrations, ratios of extraction solution to the soil, extraction time, extracted solution storage methods and time, and reaction time on soil inorganic N measurement were investigated. Results showed that all tested conditions except the storage method had a significant effect on the determination of soil NH4+-N and NO3–N. Compared with the non-stored treatment, the value of the measured soil nitrate-nitrogen increased after being stored in a refrigerator for seven weeks, while that for ammonium-nitrogen content was reduced. The appropriate protocol was using extracting solution directly to determine the content of NH4+-N and NO3–N in soil (otherwise, keep it at room temperature), 1.0 mol/L KCl as the extraction regent, solution/soil ratio with 10:1, extraction for 45 min, and reaction for 25 min (only for NH4+-N). The recovery rate of adding standard solution was above 99% as it met the detection requirements
Vertical Tillage Technology for Primary Soil Preparation
Get PDFIn the last decade in Mexico and other developing countries, soil preparation is the agricultural activity that represents the highest costs per unit of production, due to factors such as lack of appropriate equipment, excessive tillage, high consumption of fossil fuel, lack of knowledge and training for the adequate soil management, among others.
The purpose of this research was to develop a vertical tillage technology that allows primary soil preparation without investment and reduces fuel consumption and effective operating time, improves labor quality and conserves soil and water resources. For this, a chisel plow prototype was developed based on four vertical tillage parameters: (1. Working depth 2. Number of bodies 3. Spacing between chisels 4. Use of wings or sweepers). These parameters determined the criteria and dimensions of the prototype for its development in design parameters such as spacing, position, angle of attack and depth of work.
The performance evaluation of the prototype was compared with the disc plow; an implement that served as a witness as it was the most widely used technology. The standardized test method was used by the National Center for Standardization of Agricultural Machinery "CENEMA". The results obtained show a prototype plow with five chisels mounted on a double platform frame. The front platform is used for the coupling of three shallow chisels and the rear one, for the coupling of two deep chisels with wings. The implement adjusts for two working depths 0.30 and 0.40 meters and two working widths 1.80 m and 2.40 m respectively. The performance evaluation showed that vertical tillage with the chisel plow prototype in its two treatments showed an average saving of more than 45% in the fuel consumption variable and 53% in the effective working time compared to conventional tillage used with a disc plow. In terms of quality of work, vertical tillage shows high performance in soil disturbance, exceeding up to 65% of the work done by conventional tillage. Finally, it is concluded that the proposed technology should be used as technological innovation and replace the conventional disk plow technology, given its technological, economic and environmental advantages
Molecular Characterization of Mutations in Anticarsia gemmatalis Cadherin Gene and their Relation to Bacillus thurigiensis Resistance
Get PDFAnticarsia gemmatalis Hübner, 1818 is the main soybean defoliating pest in Brazil. The biological control of the species is done with products based on toxins produced by Bacillus thurigiensis (Bt), as bioinsecticides, or in transgenic plants. After activation by intestinal proteases, these toxins interact with receptors, especially cadherin, leading to death due to the formation of cellular pores. In recent years resistant populations have been identified in the laboratory, which can be a problem if the same patterns are found in crops, reducing their control effect. In this paper, we performed a comparative structural analysis of a mutation region for the gene of this receptor in A. gemmatalis, among resistant and susceptible strains treated with a toxin produced by Bt (Cry1Ac). The HaCad fragment of the cadherin gene was amplified by PCR, sequenced, and analyzed by bioinformatics tools. The PCR results were positive for resistant specimens but not for susceptible strains, suggesting the presence of a mutation in the resistant strain. In the sequenced fragments of the resistant insects, six haplotypes were found, and the originated amino acid sequences demonstrated the modification in four sites, which did not interfere with the three-dimensional shape of the protein. These data showed considerable variation taking into account the size of the fragment, even if they do not affect the final structure of the protein. The results allowed a better understanding of the mechanisms of resistance to Cry1Ac in the species, mainly in the involvement of cadherin in this process
Research on Energy Saving and Environmental Protection Electric Power Grain Circulation Drying System
Get PDFA 50-ton/batch electric grain circulation drying system was designed that adopted clean electric energy as a drying heat source. The exhaust gas of the dryer was recycled after condensation and dehumidification. The drying system has the advantages of energy saving and environmental protection. The corn drying test showed that the specific heat consumption was 3185 kJ/kg H2O in close operating mode, compared to the Chinese standard of 5700 kJ/kg H2O, and the energy consumption ratio was 44%. This research pioneers a way of saving energy and protecting the environment from drying and comes up with a new thought on how to utilize the waste heat from exhaust gas and the latent heat released by the evaporation of water vapor reasonably
Brake Power Required to Avoid Vehicular Obstruction with a Steadfast Obstacle: A Probabilistic Approach
Get PDFA probabilistic approach is applied to assess the level of the available brake power needed to avoid obstruction with a steadfast obstacle suddenly detected in front of a moving vehicle. The obtained results can be used to establish, on the design stage, the level of this power for an extraordinary situation of the type in question and for an acceptable (in effect, never-zero) probability of an accident
Characteristics of a Subclass of Analytic Functions Introduced by Using a Fractional Integral Operator
Get PDFWe define a new class of analytic functions Dm,n (λ,δ,µ,α,β) on the open unit disc using the fractional integral associated with a linear differential operator and investigate characteristics of this class: extreme points, distortion bounds, radii of close-to-convexity, starlikeness and convexity
The Unique Solution to the Differential Equations of the Fourth Order with Non-Homogeneous Boundary Conditions
Get PDFThis research paper aims to establish the uniqueness of the solution to fourth-order nonlinear differential equations
v(4)(x) + f (x,v(x)) = 0, x ε [a,b],
with non-homogeneous boundary conditions
where 0 ≤ a < ζ < b, the constants α, ???? are real numbers and f : [a,b] x R →R is a continuous function with f (x, 0] ≠ 0. Using the sharper bounds on the integral of the kernel, the uniqueness of the solution to the problem is established based on Banach and Rus fixed point theorems on metric spaces.
AMS Subject Classification: 34B15, 34B10
A Double Salt Formation from Seawater Bittern and Ammonium Sulfate
Get PDFSeawater bittern, a huge reserve containing numerous mineral materials, is an essential source for producing various industrial salts. In this work, the formation of a double salt between magnesia abundant in the seawater bittern and ammonium sulfate was studied via SEM and EDX analyses. In the next step, to optimize the efficiency of the double salt separation, the effects of technological parameters such as concentration of reactants and their ratio, as well as reaction time and temperature, were investigated. Afterward, the design of the experimental method was utilized to quantify the influence of these parameters. Based on the validation of the obtained model according to statistical criteria, only the ratio of reactants and reaction time have been shown to have decisive roles in the yield of the double salt recovery. The optimal yield reached a value of about 95%, demonstrating the feasibility of the applied technique for further processes, i.e., industrial production
Groundwater Classification by Using Fourier Analysis
Get PDFThe article illustrates a statistical technique for the visual representation of geochemical data. Quaternary and Pre-Quaternary groundwater samples from Northern Sinai Peninsula, Egypt, were interpreted statistically using Andrews plots, which use Fourier analysis to transform and represent a set of multivariate data by a waveform pattern. The resulting waveform patterns were classified into low, middle, and high amplitudes, following up the increase in the total dissolved solids of the samples. Comparison with the traditional hydrochemical polygonal Stiff diagrams resulted in a complete matching. The proposed mixing between the Quaternary and Pre-Quaternary aquifers has been proved via the similarity of waveform patterns of the mixed water. The application of Andrews plots is investigated by comparison with the Stiff conventional diagrams. The correlation between different amplitudes and the TDS value of every sample indicates that the amplitude increases with the increase in the salinity