Stability Zone Research Articles

A novel method combining strata movement and UAV infrared remote sensing technology to evaluate mining ground damage

Mining-induced ground fissures are common problems associated with mining damage in shallowly buried coal seams in the western mining area of China. To evaluate the surface mining damage of the 12203 working face of the Huojitu Colliery in Shendong mining area, low-altitude infrared aerial surveys were conducted on the ground at the static fissure area (O-A1) and the dynamic fissure area (O-A2) of the working face. The temperature evolution patterns of fissures, sand and plants in the infrared images were analysed. The relationship between overburden fractures and surface fissure temperature was revealed, and the influence range and temperature self-healing period of the surface affected by underground mining were determined. The results indicated that underground mining could lead to a decrease in the ground temperature above the working face. The surface temperature evolution can be divided into three zones: a temperature stabilization zone before mining, a temperature cooling zone during mining, and a temperature recovery zone after mining. The temperature of sand and plants above the working face exhibited quadratic curve changes in O-A1 and O-A2, respectively. The length of the temperature reduction zone affected by mining is 40 m in O-A2, and 46.8 m in O-A1. The temperature recovery periods of ground fissures in O-A1 and O-A2 were 4.0 and 4.6 d, respectively. These findings could provide a basis for evaluating mining ground damage.

Methane sealed due to the formation of gas hydrate system in the South China Sea

Although the release of methane into oceans and potentially the atmosphere could accelerate climate change, detailed investigations on the gas source from deep-buried strata and its migration through the gas hydrate stability zone (GHSZ) to the seafloor are limited. These studies are often hindered by the presence of diffracted waves and inaccuracies in seismic velocity models, leading to poor seismic imaging that hampers the understanding of gas sources, migration pathways, and gas hydrate accumulation. In the study, we utilize the technique of common scatter point (CSP) gathers to build an accurate velocity model and obtain high-quality images for a complex gas-hydrate and natural-gas petroleum system. The CSP processing enables the accurate migration of reflected and diffracted waves, resulting in improvements in signal-to-noise ratio and lateral resolution. The improved seismic images offer clearer visualization of various petroleum elements. Specifically, we can identify the top of the hydrate zone and base of the free gas zone within a shallow-buried hydrate system, fault geometries within the free gas zone, a middle-buried natural gas reservoir, gas chimneys as migration pathways, and the deep-buried source rock strata beneath the intrusive volcanic rocks. As a result, we reveal a joint prospect of natural-gas reservoir and gas-hydrate system in the deep-water region of the South China Sea. Our results suggest that methane in the natural gas reservoir has migrated upwardly into the hydrate system, and it is unlikely to leak into the water column.

Geology, geochemistry, and zircon SHRIMP U−Pb geochronology of Mesoarchean high-Mg granitoids: Constraints on petrogenesis, emplacement timing, and deformation of the Água Limpa suite in the Carajás Province, SE Amazonian Craton

Determining the age, geochemical characteristics, and conditions of deformation of Mesoarchean sanukitoids is critical to unravel the petrogenesis and tectonic significance of mantle-derived rocks. This paper reports the whole-rock major element, trace element, zircon U˗Pb age, and geochemical modelling of samples from the Água Limpa sanukitoid suite in the Sapucaia subdomain (Carajás Province, Amazonian Craton). This suite includes two plutons, named Água Limpa and Água Azul, which are exposed across E−W transpressive sinistral shear zones that act as boundaries between the Rio Maria and Carajás domains. These plutons are composed of porphyritic granodiorites, tonalites, and subordinate monzogranites, with amphibole, biotite, and epidote as the main mafic mineral components. They are characterized by high contents of Cr (383−102 ppm), Ni (117−32 ppm), MgO (4.78−2.50 wt %), Sr (912−477 ppm), and Ba (1966−519 ppm), with high Mg# values of 64−49. The REE patterns show significant fractionation of HREE with high La N /Yb N (170−18) ratios and no or weak Eu anomalies (Eu/Eu* 1.21−0.66). The studied rocks are predominantly medium-K calc-alkaline and metaluminous and are geochemically distinct from tonalite-trondhjemite-granodiorites (TTGs) and Archean leucogranodiorites. The Água Limpa and Água Azul plutons yield coeval crystallization ages of 2870 ± 4 Ma and 2872 ± 5 Ma, respectively, with other zircon population ages of 3063 ± 6 Ma, 2926 ± 12 Ma, and 2849 ± 12 Ma. The first of these other zircon populations is interpreted as xenocrysts, the second as crystals inherited from the modeled TTG-type source, and the third as crystals reflecting the age of metamorphism. Most of the suite fractionated from a common mafic parent through 20% partial melting of a mantle previously enriched by 32% TTG-type melt in the garnet stability zone and under oxidized conditions. The combined dataset indicates that the studied sanukitoids are syntectonic intrusions, with distinct pulses of magma transfer facilitated by shear zone reactivation and subordinate small-scale diking.

Application of remote sensing/GIS in the appraisal of geotechnical stability of civil engineering structures in cretaceous sedimentary units in Gombe, Northeastern, Nigeria

The increasing urbanization in Gombe township has necessitated the need for a city-wide assessment of the area to ascertain its spatial geotechnical stability. In this study, the geotechnical stability of Gombe township and environs, Northeastern, Nigeria, was appraised using the geospatial approach. Four different thematic maps (lithology, lineament, elevation, and slope) were generated in a GIS environment. Weights were allocated to the subclasses of the thematic maps based on their contribution to the stability of engineering structures. The thematic maps were integrated using ArcGIS 10.3 software to generate a geotechnical stability model of the study area, which was validated through an on-site inspection of the structures in the area. The study area was delineated into three zones: unstable (17.24%), moderate (77.2%), and stable (4.74%). The moderate zones characterised by medium elevation and slope, average lineament density, and underlain by sandstones were the predominant zones in the area. However, the stable and the unstable zones predominate in the western and eastern parts of the study area respectively. The stable zones that occur in the northwestern and southwestern zones of the study area are underlain by the Kerri-Kerri Formation while the poor and unstable areasare underlain by argillaceous materials of the Pindiga Formation. The validation of the model revealed numerous cracked buildings and bridges and a failed bridge in the unstable zones. The moderate stability zones suffer a mixed fortune, having some stable structures in some parts and failing structures in other parts. The buildings in the stable zones, however, are generally devoid of structural cracks.

Kinetics of CO2 hydrate formation in clayey sand sediments: Implications for CO2 sequestration

Hydrate-based CO2 sequestration beneath oceanic sediments is an emerging technique that involves the injection of CO2 into the hydrate stability zone (HSZ) beneath the seabed, forming hydrate cap that structurally traps the injected CO2 and reduces the risk of leaking CO2 from the storage sediment. Gas hydrates are adequately stable in sand sediments saturated with fresh water; however, the salinity of oceanic water impairs hydrate formation kinetics, stability, and CO2 storage capacity. In addition to sandstones, marine sediments are composed of many clay minerals that could affect hydrate formation. Therefore, this study experimentally simulates CO2 injection into sand and clayey sand sediments to assess the potential of CO2 hydrate formation. CO2 hydrates are formed inside a high-pressure reactor, which contains unconsolidated sediment bed/pack (silica sand; mixed sand with bentonite clay: 5 wt% and 10 wt%), saturated with de-ionized water or brine (3.3 wt% NaCl). Hydrate formation experiments were performed at 4 MPa pressure and 274.15 K temperature. Results show that CO2 hydrate formed within the sand sediment, with induction times of 6 and 8.5 h, for the de-ionized and brine systems, respectively. CO2 gas mole uptake in the de-ionized system was 71.54 mmol/mol however, in the brine system the gas uptake was 56.95 mmol/mol. Hence this 20.4% reduction in the gas uptake indicated the inhibition effect of salinity. In contrast, in the brine-saturated 5 wt% clay-sand sediment, the induction time was 6.5 h, indicating the promoting effect of the nano-sized clay particles. However, the gas uptake in this brine-saturated clay-sand sediment was reduced by 45.51% compared to the brine-saturated sand sediment. Increasing the clay content to 10 wt% prevented CO2 hydrate formation due to porosity reduction. Moreover, de-ionized water in clayey sand sediments prevented hydrate formation due to clay swelling. Finally, CO2 hydrate formation at the end of each experiment was visually confirmed.

Can adaptive prey refuge facilitate species coexistence in Bazykin’s prey–predator model?

Bazykin’s prey–predator system with constant and adaptive prey refuge is investigated in this paper. We examine Bazykin’s resource consumer system with exponential growth rate and by employing constant prey refuge we demonstrate that refuge does promote species coexistence. The incorporation of constant prey refuge expands the stability zone for the interior equilibrium. Furthermore, the bifurcation diagram with reference to prey refuge (ur) shows how ur influences the system’s behavior from unstable to periodic stability and then to equilibrium stability. Next, we provide a Bazykin’s model with adaptive prey refuge and develop a fitness function for the prey population using refuge as a strategy and in order to obtain the prey’s optimal response to the environment we determine evolutionary stable strategies (ESS). Our model consists of more than one ESS, thus we employ the best response dynamics for the prey strategy. Our analysis showcases that adaptive refuge used by the prey population promotes the coexistence of prey–predator dynamics. Our theoretical analysis is supported by extensive numerical simulations. Bifurcation diagrams with reference to the two most crucial parameters, namely, δ2 (intra-species competition rate among predators) and τ (the rate at which populations adapt to their environment), are included in the numerical analysis. Species cohabitation along a limit cycle or at an equilibrium is discovered to be dependent on the pace of strategy dynamics and the competition amongst predator species.

Varying free-gas zone (FGZ) and bottom-simulating reflection (BSR) response across a deep graben off Trujillo, central Peru

The complexity of marine gas hydrate systems at the Peruvian convergent margin has been linked to the post-Miocene history of vertical tectonics and subduction erosion that affected the forearc. Here, multichannel seismic data and published findings reveal that such a complexity has been further extended by the occurrence of the pre-Miocene deep Morsa Norte Graben (MNG) off Trujillo (8°–9° S) in the Central Peru margin. At water depths of 650–750 m in the upper slope, directly above the MNG depocentre (which has a 4–6 km overburden thickness), continuous bottom-simulating reflections (BSRs) and concentrated sub-BSR high-amplitude reflections are confined beneath a layered basin with a low–moderate near-seafloor heat flow (7–33 mW m −2 ). A deeper BSR modelled with a thermogenic gas composition is associated with the enhanced reflections. At a water depth of 900 m, sub-BSR reflections become less frequent in an area with a layered sediment cover defined by a moderate near-seafloor heat flow (15–33 mW m −2 ). At a water depth of 1200 m, where the MNG is relatively thick (3–4 km overburden thickness), faults connect patchy BSRs with a moderate–high near-seafloor heat flow (52–110 mW m −2 ). There, sub-BSR enhanced reflections are scarce. Immediately above the top of the gas hydrate stability zone (GHSZ), the near-seafloor heat flow reaches 81 mW m −2 . Modelling suggests a water depth-dependent transport of heat towards the seafloor with respect to the top of the GHSZ, implying that the closer the seafloor is to the top of the GHSZ, the lower the advection of heat, and vice versa. Recent seafloor-related depositional and structural features amplify such relations in agreement with near-seafloor heat-flow variability. However, towards the area outside the extent of the MNG (<3 km overburden thickness), continuous BSRs are not linked either to a deeper BSR or to sub-BSR enhanced reflections. The continuity of one of these BSRs is deflected upwards beneath a slump, suggesting an incomplete thermal re-equilibration of the GHSZ. Therefore, we conclude that the BSR responds to: (1) the confinement and thickening of the free-gas zone (FGZ) above the MNG depocentre due to the sealing effect of recent sedimentation close to the top of the GHSZ; (2) the seepage of gas-rich fluids from a thinned FGZ above the relatively thick MNG, due to the enabling effect of faults cutting the GHSZ far from the top of the GHSZ; (3) the undisturbed state of the FGZ outside the extent of the MNG; and (4) the disequilibrium state of the base of the GHSZ due to the unloading of sediments in an unstable slope environment prone to failure.

Shallow subsurface fluid dynamics in the Malvinas Basin (SW Atlantic): A geoacoustic analysis

Using a database consisting of sub-bottom profiles, 2D and 3D seismic data, a series of seep structures and acoustic anomalies associated with a plumbing system in the subsurface of the southern part of the Malvinas Basin off the Argentine coast are presented. The seep morphologies consist of mounds, pockmarks, and a carbonate mound, derived from hydrocarbons migrating from the Early Cretaceous Springhill and Lower Inoceramus formations through extensional faults and overthrusts of the Malvinas Fold-Thrust Belt and accumulating in the gas hydrate stability zone. This configuration is widely observed in the anticlines of the Malvinas Fold-Thrust Belt, which are characterized by a vertical structure highlighting a Bottom Simulating Reflector (BSR) overlain by a blanked-out zone at the seabed, interpreted as a gas hydrate stability zone. The plumbing system is influenced by active transtensional tectonics, as shown by two sets of extensional faults concentrated over some anticlines. These faults lead to displacements that, in many cases, reach the seabed. One nuance of the influence of tectonic activity on fluid escape is most evident in the Malvinas anticline, where all the pockmarks and the carbonate mound are concentrated. In the western part of the Malvinas anticline, five pockmarks are observed in an area characterized by a shallow BSR. In contrast, in the eastern part of the Malvinas Basin, one pockmark and one carbonate mound are derived from a series of extensional faults. The presented data, as well as a comparison between the western and eastern parts of the Malvinas anticline, indicate that the anticlines are the main cause of seepage in this area, as they allow the accumulation of migrating fluids. Likewise, the seepage morphologies outside the anticlines are much less pronounced, as can be observed in the mounds that overlie the bottom vents.

Reasonable layout range of lower mining roadways in the close and variable interval coal seams mining: a case study.

In the context of close-distance coal seam mining, the stress transfer mechanism following the extraction of the upper coal seam is crucial for the layout of roadways in the lower coal seam. This study utilizes ground-penetrating radar (GPR) to analyze the stability and plastic zone extent of residual coal pillars after upper seam extraction. A theoretical model for the stress distribution of multiple goaves and coal pillars was established. Based on a case study with variable inter-seam spacing, the stress distribution and transfer mechanisms of the floor were analyzed. The results indicate that during the transition from the center of the coal pillar to the goaf, stress concentration initially decreases significantly and then gradually returns to the original rock stress, forming a distinct stress gradient distribution. As the depth of the floor strata increases, the weight of the overlying strata is more evidently transferred through the coal pillars to the goaf. Finally, a reasonable layout range for the lower seam mining roadways under different inter-seam spacings is proposed, providing a reference for optimizing roadway layout in similar geological conditions.

Using calcaneal plates in fixation of comminuted posterior wall acetabular fractures with cranial or posterior extension: a prospective case series and novel technique.

This study aims to evaluate the outcomes of using calcaneal plate in fixation of comminuted posterior wall (PW) acetabular fractures especially that have cranial (dome) or posterior extension (posterior column edge), and to evaluate its safety. To our knowledge, this is the first study that utilizes this off label implant technique in fixation of such fracture. Twenty-two patients enrolled in the study with a minimum follow up of one year. After reducing the PW fragments sequentially, calcaneal plate was applied, fixing its distal part at ischial tuberosity upper ends using 3 screws in a triangular fashion, while its proximal part and radial wings were firmly fixed along the acetabular rim together with the classic longitudinal anchorage. Any fixation failure or head subluxation was recorded. Radiological outcome showed 18 cases scored as excellent, 2 were good, and 2 were poor. The functional outcome revealed 2 patients were excellent, 6 were very good and 14 were good. There was no loss of reduction or fixation failures throughout the follow up period. Calcaneal plate may offer an alternative method of fixation of comminuted PW fractures with acceptable radiological and functional results. Our study result may encourage the comprehensibility and replicability of this practice, however randomized multicentered studies should be conducted to validate this assumption. This method provides valuable trick strategy, stable and soft-tissue-friendly fracture fixation where modern implantations may be unavailable or of high cost. Calcaneal plates show some fascinating features that allow using them outside their field being flexible with large footprint area for fracture buttressing beside numerous hole choices with diverse paths providing suitable fixation, articular stability and wide zone of coverage in PW comminuted fracture patterns with cranial or posterior extensions. The plate proximal triangular configuration together with distal triangular screw fixation gives a stiff rigid anchorage and buttressing similar to a metal mesh covering and fixing any fragment numbers up to dome level.

Shoaling of the gas hydrate stability zone inferred from 3D seismic data of the Cauvery basin

Shoaling of the gas hydrate stability zone inferred from 3D seismic data of the Cauvery basin

Geo-Environment Aspects Assessment Applied In Land Stability Determination Of A Disaster-Prone Area: A Case Study Around The Lembang Active Fault Zone, On The Western Part Of Bandung Basin, Indonesia

Rainfall, landforms, lithology or soil characteristics, and geological structures are geo-environment aspects that might be used to assess stability of the land in a disaster-prone area, e.g. in a case of study around the Lembang active fault zone of the western part of Bandung Basin, Indonesia. In this study, such geo-environment aspects were weighted and scored constantly in five class of value and importance, due to its influence on the land stability. After this scoring method applied, firstly, a land capability of the research area in relation to disaster potential will be recognized and used to analyze its land stability. According to such analyses, the study area can be divided into two zones of land stability, i.e. (i) moderate area which dominates the research area, and (ii) non-stable or unstable area near Lembang active fault zone. The dominant moderate and unstable area show that the fault zone has still widely affected the surroundings landscape and its physical characteristics. In fact, the current evaluation of existing landuse show that the development has been carried out intensively on these areas. It indicates that the development of the area is contituted as a high risk activity. Therefore, in this case, a good spatial planning or an environmental good governance must be applied appropriately in such disaster-prone area.

METHOD FIRST APPROXIMATION STABILITY ANALYSIS OF ELECTRICAL CONTROL SYSTEMS

This article is devoted to the research and analysis of automated control systems and control of electrical equipment of technological processes of agricultural production. The first approximation method is used for evaluation the stability of the operation of electric drive control systems. Methods for assessing the stability zone of electric drive control systems, determining critical gain coefficients, and optimizing the parameters of electrical circuits included systems, in order to increase the efficiency and reliability of production chains are proposed. To solve the problem of controlling the electric drives of automated systems for harvesting and sorting agricultural crops, the method was tested, a critical gain value of 3.2 was obtained, which allows us to talk about optimizing such systems in terms of speed and load.

Gas hydrate inhibition by urea and its blends with vinyl lactam polymer: Paving the way to green hybrid inhibitors

Urea is an environmentally benign substance considered a promising gas hydrate inhibitor in flow assurance. Nevertheless, its effect on gas hydrate formation kinetics remains poorly understood. This study investigates the impact of urea and hybrid urea/polymer KHI samples on the nucleation and growth kinetics of sII natural gas hydrates. Hydrate formation was observed at a lower onset temperature with increasing urea and polymer concentration. The nucleation of sII hydrate in aqueous urea solutions occurred at a higher subcooling (7.50 ± 0.58 K at 30 mass%) than in pure water (5.17 ± 0.69 K). These findings indicate that urea acts as a nucleation inhibitor of sII hydrates, although its capacity is not as potent as that of polymer KHI.The analysis of the hydrate nucleation probability distributions revealed that the sII hydrate nucleation rate exhibited a significant decline, approximately one order of magnitude, at subcooling of 5.3–6 K for 20 mass% urea compared to water. A similar behavior was noticed in an aqueous solution of polymer KHI. Urea has succeeded in providing a total benefit of up to 10 K in hydrate onset temperature due to a shift in the hydrate stability zone and nucleation retardation.Consequently, urea is a green dual-acting anti-hydrate chemical that inhibits the formation of sII hydrates by thermodynamic and kinetic mechanisms. Besides, adding 10 mass% urea increases the cloud point temperature of vinyl lactam polymer Luvicap 55W by 14 K. Urea is an additive that considerably augments the stability of the polymer in aqueous solutions at elevated temperatures. These findings make urea an effective and environmentally friendly top-up inhibitor that significantly enhances the anti-hydrate properties of polymer KHI.

Sedimentary Greigite Formation

Revised thermodynamic data for greigite (Fe3S4) indicate that it is a stable sedimentary Fe-S phase. Greigite was previously regarded as metastable. Equilibrium computations using revised data explain apparently contradictory observations regarding greigite occurrences in sediments and sedimentary rocks. Greigite has a large stability area in pe-pH space relative to pyrite. It dominates in low pe regimes especially near the lower water stability boundary, which is consistent with its widespread occurrence in methanic sediments. It also has a small but significant stability zone near the sulfate-sulfide stability boundary. Its significance increases in regimes with relatively high dissolved Fe:S ratios, which explains its occurrence in freshwater sediments and iron-enriched marine sediments. It is also a paleoenvironmental marker for transitional environments, especially between freshwater and marine systems. It is stable relative to pyrrhotite and smythite, although their formation together with greigite in low pe environments may be facilitated by catalytic processes. The greigite-smythite (pyrrhotite)-siderite association is a potential marker for ancient methanogenesis. Greigite is relatively sensitive to oxidation and its long-term geological preservation depends mostly on protection from oxidation by low sediment permeability or enclosure in other minerals or organic remains. Most sedimentary and biological greigite forms via equilibrium reactions involving mackinawite-like precursors, with no direct coupling of greigite with pyrite; these minerals form independently during sedimentary diagenesis. Magnetosomal greigite production by magnetotactic bacteria is a consequence of relative greigite stability, its decoupling from pyrite, and its protection from oxidation by cell membranes.

A New Methodology for the Development of Efficient Multistep Methods for First–Order IVPs with Oscillating Solutions IV: The Case of the Backward Differentiation Formulae

A theory for the calculation of the phase–lag and amplification–factor for explicit and implicit multistep techniques for first–order differential equations was recently established by the author. His presentation also covered how the approaches’ efficacy is affected by the elimination of the phase–lag and amplification–factor derivatives. This paper will apply the theory for computing the phase–lag and amplification–factor, originally developed for implicit multistep methods, to a subset of implicit methods, called backward differentiation formulae (BDF), and will examine the impact of the phase–lag and amplification–factor derivatives on the efficiency of these strategies. Next, we will show you the stability zones of these brand-new approaches. Lastly, we will discuss the results of numerical experiments and draw some conclusions about the established approaches.

Stability of a viscous liquid film flowing down an inclined plane with respect to three-dimensional disturbances

An analysis is presented for the stability of a viscous liquid film flowing down an inclined plane with respect to three-dimensional disturbances under the action of gravity and surface tension. Using momentum-integral method, the nonlinear free surface evolution equation is derived by introducing the self-similar semiparabolic velocity profiles along the flow (x- and y-axis) directions. A normal mode technique and the method of multiple scales are used to obtain the theoretical (linear and nonlinear stability) results of this flow problem, which conceive the physical parameters: Reynolds number Re, Weber number We, angle of inclination of the plane θ and the angle of propagation of the interfacial disturbances ϕ. The temporal growth rate ωi+ and second Landau constant J2, based on which various (explosive, supercritical, unconditional, subcritical) stability zones of this flow problem are categorized, contain the shape factors B and β owing to the non-zero steady basic flow along the y-axis direction. A novel result which emerges from the linear stability analysis is that for any given value of Re, We and θ, any stability that arises in two-dimensional disturbances (ϕ = 0) must also be present in three-dimensional disturbances. For ϕ = 0, there exists a second explosive unstable zone (instead of unconditional stable zone) after a certain value of Re (or θ) due to the involvement of B and β in the expression of J2. This explosive unstable zone vanishes after a certain value of ϕ depending upon the values of Re, We and θ, which confirms the stabilizing influence of ϕ on the thin film flow dynamics irrespective of the values of Re, We and θ.

Analyzing the Stability of a Connected Moving Cart on an Inclined Surface with a Damped Nonlinear Spring

This paper examines the stability behavior of the nonlinear dynamical motion of a vibrating cart with two degrees of freedom (DOFs). Lagrange’s equations are employed to establish the mechanical regulating system of the examined motion. The proposed approximate solutions (ASs) of this system are estimated through the use of the multiple-scales method (MSM). These solutions are considered novel as the MSM is being applied to a new dynamical model. Secular terms have been eliminated to meet the solvability criteria, and every instance of resonance that arises is categorized, where two of them are examined concurrently. Therefore, the modulation equations are developed based on the representations of the unknown complex function in polar form. The solutions for the steady state are calculated using the corresponding fixed points. The achieved solutions are displayed graphically to illustrate the impact of manipulating the system’s parameters and are compared to the numerical solutions (NSs) of the system’s original equations. This comparison shows a great deal of consistency with the numerical solution, which indicates the accuracy of the applied method. The nonlinear stability criteria of Routh–Hurwitz are employed to assess the stability and instability zones. The value of the proposed model is exhibited by its wide range of applications involving ship motion, swaying architecture, transportation infrastructure, and rotor dynamics.

Emergence delay effect on maize (Zea mays L.) nitrogen uptake

AbstractSpatial and temporal variability in plant emergence may cause differences in nitrogen (N) uptake by crops leading to a mismatch between plant nitrogen requirements and nitrogen supply, with negative environmental and economic impacts. We aimed to understand N uptake and concentration (%) in unevenly emerged plants by conducting experiments in pre‐determined yield stability zones (YSZs) in three farmers’ fields planted to maize (Zea mays L.). We found that maize emergence ranged from 64 to 124.1°C day, with significant variability between YSZ in two of three fields. Maize biomass plant‐to‐plant variation decreased from maize six leaves stage (V6) to maize silking stage (R1). At maize physiological maturity (R6), biomass ranged from 54 to 736 g plant−1 and was significantly affected by YSZ (p < 0.001). In the cases where late‐emerging plants accumulated less N than early emerging plants, this led to altered N partitioning within the plant (i.e., nitrogen harvest index decrease). Although N concentration in the grains remained unaffected by late emergence, the N concentration in the biomass increased. This was likely due to a reduced total biomass and the lack of a N sink (i.e., less yield per plant due to less grain per plant). The absence of variations in N utilization across emergence classes, coupled with the significant impact observed in the YSZ, reinforces the advantages of focusing on N management fitted to YSZ. Understanding the impact that the spatial and temporal variation of plant emergence has on maize N uptake is important in helping to improve N input prescription maps, N‐use efficiency, and reduce N losses to the environment.

Impact of driver prediction with density deviation and anticipation in lattice hydrodynamic model with passing

This paper presents an integral lattice hydrodynamic model to examine the impact of driver’s anticipation and driving prediction with density deviation of leading vehicle under passing behavior. Both linear and nonlinear investigations have been used to obtain the stability condition and ‘modified Korteweg–de Vries (mKdV)’ equation is derived to further classify the nonlinear behavior of vehicular flow in terms of density waves, respectively. The linear stability condition shows that the stable region can be increased by decreasing the coefficient of predicted density deviation. Additionally, the stable region expands with a positive value of driver anticipation but contracts with a negative value. In comparison of the Nagatani and Redhu models, it is observed that for fixed value of density deviation coefficient, the new model conveys greater stability zone. To verify the theoretical findings, ‘numerical simulation’ has been conducted to examine the evolution of traffic flow in the presence of a small disturbances. The analytical results have been discussed for different passing rate with fixed value of driver’s anticipation and different values of density deviation coefficient. Furthermore, it has been noted that the stable region decreases for all passing rates when driver become more aware of the average speed of any neighbouring vehicles. The obtained results in this paper show that the traffic behavior with the existing model is more realistic. Additionally, this model will help in boosting vehicle movement efficiency, reducing congestion and enhancing road safety effectively .