Stationary Field Research Articles

Yield and Quality of Winter Durum Wheat Grain Depending on the Fertiliser System

At present, winter durum wheat is grown after its unpaired predecessors. Under such conditions, fertiliser is important. Therefore, the study of the yield formation and quality of winter durum wheat grain depending on the fertiliser system is relevant. The purpose of this study was to investigate the yield formation and quality of winter durum wheat grain under various fertiliser systems. The study was conducted in conditions of a stationary field experiment of the Uman National University of Horticulture, located in the Right-Bank Forest-Steppe of Ukraine during 2020–2021. The experiment was founded in 2011. The following crops are grown in the four-course field crop rotation: winter wheat, corn, spring barley, soybeans. The experiment scheme includes 11 variants of combinations and separate application of mineral fertilisers, including the control option without fertiliser. Grain harvest was performed by direct combining, protein content and gluten content were determined by infrared spectroscopy using Infratek 1241. Statistical data processing was performed using the STATISTICA 10 software. Yield of winter durum wheat grain significantly increased from the fertiliser. However, the effectiveness of their use varied depending on the year of study. Thus, in 2020, it increased by 1.1–1.2 times (3.9-4.1 t hа-1) with long-term use of nitrogen fertilisers alone. Long-term use of complete mineral fertiliser (N150P60K80) significantly affected the grain yield (4.3 t hа-1) compared to variant N150. In 2021, grain yields increased 1.2–1.4 times, depending on the fertiliser system. Notably, the use of N150P60K40 and N150P30K80 in terms of impact on grain yield was at the level of the variant N150P60K80. Paired combinations of fertiliser application were effective at the level of long-term application of N150P30K40. Application of N75P30K40 provided the formation of only 4% lower grain yield compared to N150P30K40. The protein and gluten content was most affected by the nitrogen component of the complete mineral fertiliser. The conducted studies confirm the high reaction of durum wheat to the use of nitrogen fertilisers. The results obtained can be used to predict the productivity of durum winter wheat depending on soil fertility

Point processes of exceedances by Gaussian random fields with applications to asymptotic locations of extreme order statistics

In this paper, we studied the limit properties of the point processes of exceedances by stationary dependent Gaussian random fields. Applying the obtained results, we investigated the asymptotic relations between the locations and heights of extreme order statistics for stationary dependent Gaussian random fields. It is shown that these asymptotic relations are not sensitive to the dependence of the Gaussian random fields.

Stationary wave biases and their effect on upward troposphere– stratosphere coupling in sub-seasonal prediction models

Abstract. The simulated Northern Hemisphere winter stationary wave (SW) field is investigated in 11 Subseasonal-to-Seasonal (S2S) prediction project models. It is shown that while most models considered can well simulate the stationary wavenumbers 1 and 2 during the first 2 weeks of integration, they diverge from observations following week 3. Those models with a poor resolution in the stratosphere struggle to simulate the waves, in both the troposphere and the stratosphere, even during the first 2 weeks. Focusing on the tropospheric regions where SWs peak in amplitude reveals that the models generally do a better job in simulating the northwestern Pacific stationary trough, while certain models struggle to simulate the stationary ridges in both western North America and the North Atlantic. In addition, a strong relationship is found between regional biases in the stationary height field and model errors in simulated upward propagation of planetary waves into the stratosphere. In the stratosphere, biases are mostly in wave 2 in those models with high stratospheric resolution, whereas in those models with low resolution in the stratosphere, a wave 1 bias is evident, which leads to a strong bias in the stratospheric mean zonal circulation due to the predominance of wave 1 there. Finally, biases in both amplitude and location of mean tropical convection and the subsequent subtropical downwelling are identified as possible contributors to biases in the regional SW field in the troposphere.

Effects of spatial variability of soil properties and ground motion characteristics on permanent displacements of slopes

The seismic performance of earth slopes is a problem of great importance in geotechnical earthquake engineering associated with various sources of uncertainty. This research investigates the effects of two important causes of such uncertainty: (a) the spatial variability of soil properties and (b) the variability of the temporal and frequency characteristics of the earthquake excitation. The former is investigated based on a series of detailed dynamic numerical simulations using stationary random fields of both cross-correlated and spatially autocorrelated soil properties. The latter is explored by conducting incremental dynamic analysis at various levels of excitation intensity using (a) a total of forty historic earthquake and synthetic records, modified to match the Eurocode 8 design spectra for rock sites, and (b) thirty original historic earthquake records. The results demonstrate the significant effect of the spatial variability of soil properties on the permanent slope displacements. Moreover, they show that the effect of the uncertainty associated with the variability in the temporal and frequency characteristics of excitations is more important compared to the effect of the spatial variability of soil properties.

Asymptotic spectral theory for spatial data

ABSTRACT In this paper, we study the asymptotic theory for spectral analysis of stationary random fields on , including linear and nonlinear fields. Asymptotic properties of Fourier coefficients and periodograms, including limiting distributions of Fourier coefficients, and the uniform consistency of kernel spectral density estimators are obtained under various mild conditions on moments and dependence structures. The validity of the aforementioned asymptotic results for estimated spatial fields is also established.

Coupling of stationary fields with application to arithmetic waves

In this paper we obtain a range of quantitative results of the following type: given two centred Gaussian fields with close covariance kernels we construct a coupling such that the fields are uniformly close on some compact with probability very close to one. As an application we show that it is possible to couple arithmetic random waves so that they converge locally uniformly to the random plane wave and estimate the rate of convergence.

Некоторые биофенологические характеристики мохнатой бронзовки Epicometis hirta (Poda, 1761) в Шеки-Закатальской зоне

Coleoptera occupies a special place in the class of insects that annually cause great damage to agricultural plants. Of particular agricultural importance among these pests is the shaggy bronze, belonging to the family of Scarabaeidae. The damage caused by this pest to the stone fruit trees of the Sheki-Zagatala zone, the dynamics of development in horticulture, periods of activity in agrocenoses and phenological calendars have not been studied in detail. The article reflects the results of research on the ecology of the shaggy bronze. The study of bioecological and phenological characteristics of stone fruit pests in the Sheki-Zagatala zone was carried out on stationary fields in 2017–2021. The material was collected in agrocenoses and biocenoses during the year. The collection and identification of species, the conduct of experiments, and the mathematical processing of the results were carried out by methods generally accepted in entomology. As a result, it was established that the shaggy bronze develops in one generation in the Sheki-Zagatala zone. Pests go into diapause during the pupation period. Although the seasonal dynamics of the flight of the shaggy bronze is a curve with one peak, the daily dynamics of flight is a curve with two peaks. In spring, there is a one-peak curve, and in summer, a two-peak curve, depending on the weather temperature. The results of the research can be taken into account in the development of integrated pest control measures.

Statistics of rogue waves in isotropic wave fields

We investigate the statistics of rogue waves occurring in the inverse cascade of surface gravity wave turbulence. In such statistically homogeneous, stationary and isotropic wave fields, low-frequency waves are generated by nonlinear interactions rather than directly forced by a wave maker. This provides a laboratory realization of arguably the simplest nonlinear sea state, in which long-time acquisitions are performed and compared with theoretical models. The analysis of thousands of rogue waves reveals that some of their properties crucially depend on four-wave resonant interactions, large crests being for instance more likely than predicted by second-order models.

DIRECTION OF MINERALIZATION-SYNTHESIS PROCESSES OF ORGANIC MATTER IN LEACHED CHORNOZEM UNDER VARIOUS FERTILIZATION OF SPRING BARLEY

Objective. To investigate the direction of mineralization-synthesis processes of organic matter in the soil during the cultivation of spring barley in different agrobackgrounds using new methodical solutions. Methods. Field experiment, gas chromatography (to determine the emission of nitrous oxide and carbon dioxide), statistical. Results. The study of the emission of nitrous oxide and carbon dioxide and subsequent calculations of the specific losses of N-N2O (g/kg С-СО2) depending on the fertilization systems and in comparison with the parameters in the “reference” soil (fallow) provide an opportunity to quickly determine the direction of mineralization-synthesis processes of organic matter in the soils of agrocenoses. Under the conditions of a stationary field experiment on leached chornozem during the cultivation of spring barley in crop rotation, it was shown that the use of mineral fertilization systems leads to the initiation of mineralization processes, the intensity of which increases with an increase in the rates of fertilizers. The application of mineral fertilizers against the background of the first year aftereffect of organic matter (5 t/ha of straw + 13 t/ha of the mass of intermediate lupine green manure) significantly improves the situation. At the same time, when using the lowest (N30P30K30) and medium (N60Р60К60) doses of mineral fertilizers in the experiment against the background of the aftereffect of organic fertilizers, the soil is characterized by the dominance of organic matter synthesis processes. The highest rate of fertilizers in the experiment (N90Р90К90), even if it is used against the background of the aftereffect of straw with lupine green manure biomass, leads to the activation of mineralization processes. Under the aftereffects of cattle manure, lupine green manure and their combination, including with mineral fertilizers, there is a slight predominance of mineralization activity over immobilization activity. Conclusion. The use of the gas chromatography in finding out the direction of mineralization-synthesis processes of organic matter makes it possible to quickly determine the ecological expediency of crop fertilization systems. To optimize the course of processes, it is advisable to combine the use of mineral fertilizers against the background of organic ones.

ДИСПЕРСІЙНИЙ АНАЛІЗ ПОЗДОВЖНІХ ІМПУЛЬСІВ ДЕФОРМАЦІЙ У КАНАТАХ МІНІМАЛЬНОЇ МАСИ ВАНТАЖОПІДЙОМНИХ МЕХАНІЗМІВ КРАНІВ

Dispersion analysis of longitudinal deformation pulses in minimum mass ropes of cranes load lifting mechanisms (which satisfy the conditions of equal strength in each specific cross section) is carried out in the article. The phase and group waveform velocities occurring in the ropes of this type are determined. The impulse dispersion by the method of lifting the load "with the pickup"/"from the base" ("from the ground") was investigated using the stationary phase method. Such methods are used in this work as: 1) classic methods of mathematical physics; 2) complex Fourier transform over time; 3) stationary phase method for the calculation of the integral which characterizes the deformations in the remote field during its asymptotic schedule. It is shown that the asymptotic schedule reduces the analysis of stress and deformation wave fields arising in the rope to the using of the Airy function with a complex argument. The sign of this argument is determined by the sign of the third derivative of the frequency by the wave vector for mentioned above fields near stationary points of the group velocity of wave formations (hear, in accordance, the second derivative is equal to zero). It is substantiated that Airy function is responsible for reproducing the nature of perturbations before and after the wave front moving inside the rope system. The phase velocity with which the constant phase plane of the exponential multiplier is carried in the rope is determined. This multiplier the spatial-temporal dependence of the emerging waveform describes. Near the pulse front (load/deformation of the rope), its duration increases, but the amplitude decreases in proportion to the cubic root of the distance to the observation point. The formula is established, according to which the asymptotic of this problem solution should be built, in the case of the curve extreme of waveform propagation group velocity in the rope. A similar approach gives the possibility to explore the main patterns of no stationary wave fields generated in the ropes of cranes load lifting mechanisms. The results obtained in the work can be used for establishing cranes rope systems loads and deformations quantities estimates under the condition of their transience. Such loads/deformations usually cause of the above systems overstrain when lifting or lowering loads with different types cranes (particularly, bridge, gantry, portal), which work in operation modes (real operation mode) and can lead to emergencies (for example, breaks in rope systems).

Central limit theorems for stationary random fields under weak dependence with application to ambit and mixed moving average fields

We obtain central limit theorems for stationary random fields employing a novel measure of dependence called θ-lex weak dependence. We show that this dependence notion is more general than strong mixing, that is, it applies to a broader class of models. Moreover, we discuss hereditary properties for θ-lex and η-weak dependence and illustrate the possible applications of the weak dependence notions to the study of the asymptotic properties of stationary random fields. Our general results apply to mixed moving average fields (MMAF) and ambit fields. We show general conditions such that MMAF and ambit fields, with the volatility field being an MMAF or a p-dependent random field, are weakly dependent. For all the models mentioned above, we give a complete characterization of their weak dependence coefficients and sufficient conditions to obtain the asymptotic normality of their sample moments. Finally, we give explicit computations of the weak dependence coefficients of MSTOU processes and analyze under which conditions the developed asymptotic theory applies to CARMA fields.

Magnetization of alloys of (Tb1−xYx)0.8Sm0.2Fe2 system in stationary and pulsed magnetic fields

The paper presents the results of studying the alloy magnetization of the multicomponent system (Tb1−xYx)0.8Sm0.2Fe2. The substitution parameter in this system takes the following values: x = 0, 0.2, 0.4, 0.6, 0.8, 1. In the system, the atoms of magnetic terbium were replaced by atoms of weakly magnetic samarium and nonmagnetic yttrium. X-ray diffraction analysis determined the structure and lattice constant for all compositions. Phase analysis was carried out. It is known that by varying the concentration of components, temperature, and external fields, one can successfully influence the magnitude of exchange interactions leading to one or another type of magnetic ordering in the rare-earth intermetallic metals. Therefore, the main goal in this work was to investigate the possibility of observing the magnetic phase transition – ferrimagnetism – ferromagnetism - in the alloys of the system from the curves of the field dependence of magnetization in strong fields up to 60 T. The studies were carried out at the liquid helium boiling point. The main magnetic characteristics of the alloys of this system were determined, such as saturation magnetization σs, magnetic moment per formula unit μ and magnetic moment μFe on iron atoms. Their dependences on the concentration of yttrium were established. The possible values of the magnetic moment per formula unit in the case of ferromagnetic ordering of these alloys were calculated theoretically. It was concluded that these fields are insufficient to observe the ferrimagnetism – ferromagnetism phase transition.

Coherence-orbital angular momentum matrix of Schell-model sources.

The coherence-orbital angular momentum (COAM) matrix characterizes the second-order field correlations in stationary sources or fields, at a pair of spiral modes with the same or different topological charges, say l and m, and at a pair of radial positions. In this Letter, we reveal the general properties of the COAM matrix for the broad class of the Schell-model sources with circularly symmetric spectral densities. Our results imply that the structure of the COAM matrix is intimately related to the symmetries of the degree of coherence (DOC). In particular, the COAM matrix is diagonal if the DOC is real-valued and rotationally symmetric; otherwise, it may acquire non-zero off diagonal elements. In particular, if the real part of the DOC has Cartesian symmetry, the COAM matrix's elements with the even/odd index difference |l - m| contain information about the real/imaginary part of the DOC. A potential application of our results is envisioned for extracting the rotation angle of the DOC of light (or an object transparency) through measuring of the off-axis COAM matrix elements.

A computational approach based on extended finite element method for thin porous layers in acoustic problems

AbstractThe simulation of stationary acoustic fields involving thin porous layers is addressed in the present article. Layer thickness is assumed to be relatively thin in comparison to the overall computational domain, but its non‐negligible acoustic impact must be taken into consideration in the numerical model. Within the classical finite element method (FEM), meshes are compatible at material interfaces and the element distortions needs to be avoided. These requirements usually lead to an excessively costly spatial discretization for these problems of interest, as it forces mesh refinement surrounding the thin layer. This article provides a computational approach to relax this restriction. A generalized interface model derived from the plane wave transfer matrix Method (TMM) is established for modeling thin layers. We develop variationally consistent formulations to impose the interface conditions from models of thin layers for diverse coupling configurations, in which both acoustic fluid and poro‐elastic media are taken into account. The computational domain is discretized using the extended finite element method (X‐FEM) in order to introduce strong discontinuities in elements independently of the mesh. Implementation of the proposed formulations within X‐FEM is verified to be capable of providing accurate and robust solutions. The efficiency and flexibility of the present approach for multi‐layer and complex geometry problems are demonstrated compared to classical interface‐fitted finite element models through different simulation scenarios.

Extrapolation of stationary random fields via level sets

In this paper, we use the concept of excursion sets for the extrapolation of stationary random fields. Doing so, we define excursion sets for the field and its linear predictor, and then minimize the expected volume of the symmetric difference of these sets under the condition that the univariate distributions of the predictor and of the field itself coincide. We illustrate the new approach on Gaussian random fields.

Boundedness of the nodal domains of additive Gaussian fields

We study the connectivity of the excursion sets of additive Gaussian fields, i.e. stationary centred Gaussian fields whose covariance function decomposes into a sum of terms that depend separately on the coordinates. Our main result is that, under mild smoothness and correlation decay assumptions, the excursion sets { f ≤ ℓ } \{f \le \ell \} of additive planar Gaussian fields are bounded almost surely at the critical level ℓ c = 0 \ell _c = 0 . Since we do not assume positive correlations, this provides the first examples of continuous non-positively-correlated stationary planar Gaussian fields for which the boundedness of the nodal domains has been confirmed. By contrast, in dimension d ≥ 3 d \ge 3 the excursion sets have unbounded components at all levels.

Constructing chiral effective field theory around unnatural leading-order interactions

A momentum-dependent formulation based on a stationary spin-0 and isospin-1 dibaryon field is proposed to improve convergence of chiral effective field theory in the ${}^{1}{S}_{0}$ channel of $NN$ scattering. Although the two-parameter leading-order interaction appears to be unnatural, it nevertheless has the necessary features of an effective field theory. A rapid order-by-order convergence is found in ${}^{1}{S}_{0}$. As an application beyond the two-body level, the triton binding energy is studied and compared to standard chiral effective field theory with partly perturbative pions. The consistency of the chiral Lagrangian for the new formulation is examined by working out the pionic radiative corrections, and consequences of nontrivial chiral-connection terms are discussed.

Nonparametric regression for locally stationary random fields under stochastic sampling design

In this study, we develop an asymptotic theory of nonparametric regression for locally stationary random fields (LSRFs) {Xs,An:s∈Rn} in Rp observed at irregularly spaced locations in Rn=[0,An]d⊂Rd. We first derive the uniform convergence rate of general kernel estimators, followed by the asymptotic normality of an estimator for the mean function of the model. Moreover, we consider additive models to avoid the curse of dimensionality arising from the dependence of the convergence rate of estimators on the number of covariates. Subsequently, we derive the uniform convergence rate and joint asymptotic normality of the estimators for additive functions. We also introduce approximately mn-dependent RFs to provide examples of LSRFs. We find that these RFs include a wide class of Lévy-driven moving average RFs.

Influence of fertilization on the crop rotation productivity and the balance of essential nutrients in the soil

The article shows the influence of different rates and combinations of mineral fertilizers on the balance of essential nutrients in the four-field crop rotation (winter wheat, corn, spring barley, and soybean) during eight years in the context of incorporation into the soil or removal of a non-commercial part of the yield of the field. The stationary field experiment was performed on the black podzolized heavy loamy soil of the Right-Bank Forest-Steppe. The experiment scheme included 11 variants of combinations and separate applications of mineral fertilizers as well as control variants without fertilization. It has been established that in the annual removal of nutrients together with grain harvest nitrogen makes up the biggest share (64.4–149.9 kg hа-1), then phosphorus – 21.1–51.4 kg hа-1 depending on the fertilizing in the crop rotation. The variant of the experiment N110P60K40 provides the optimal intensity of the balance of nitrogen, phosphorus, and potassium (103, 122, and 111%, respectively) when a non- marketable part of the yield is left for fertilizing in the field. When this part of the yield is removed from the field there is a deficit balance of nitrogen, phosphorus, and potassium with the intensity (76, 76, 61%, respectively) even in the variant with the annual average application of N110P60K80. The use of non-marketable agricultural products in crop rotation for fertilization and the average annual application of N110P30–60K40–80 allows compensation for the losses of nitrogen 24%, phosphorus 33%, and potassium 71%

Taking into account convective heat and mass exchange in autoclave reactors when scaling hydrothermal and hydrometallurgical processes

The article presents the procedure of scaling the processes of hydrothermal synthesis for various dispersed inorganic materials and selection of an optimal technological mode for a given autoclave reactor on the base of a reaction kinetics experimental study with applying in situ heat flux calorimetry and developing the reaction mathematical model to simulate temperature and conversion fields inside a chosen apparatus for the selected mode. Natural convection is shown to be the main driving force for heat exchange and mass exchange in autoclave reactors without mechanical mixing and heating with a jacket. This may lead to a considerable non-homogeneity of temperature and concentration fields inside the reactor and be the reason of phase composition and particle size variations as well as real crystal structure of reaction products non-reproducibility. Applying an optimal heating mode with temperature linear programming on the wall results in forming stationary fields of temperature and concentrations inside the reactor and makes it possible to monitor the current conversion along the apparatus cross-section and minimize corresponding gradients in the final point. It is also possible to evaluate overheating of the reaction mixture for a hydrometallurgical process in the batch stirred reactor or continuous flow reactor. The proposed procedure makes it possible to select an optimal technological mode for producing a definite product in a definite apparatus on the base of a hydrothermal or hydrometallurgical reaction kinetic model with heat generation or heat absorbtion. The author would like to thank the leadership of the Saint Petersburg Mining University for their extensive support of the basic studies into hydrothermal synthesis of dispersed inorganic materials and that of mathematical modelling work.