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(R1464) Stability of the Artificial Equilibrium Points in the Low-Thrust Restricted Three-Body Problem with Variable Mass
Get PDFIn this article, we have investigated the existence and stability of the artificial equilibrium points (AEPs) in the low-thrust restricted three-body problem with variable mass. In this model of the low-thrust restricted three-body problem, we have considered both the primaries as point masses. The mass of the spacecraft varies with time according to Jeans’ law (1928). We have introduced a new concept for creating the AEPs in the restricted three-body problem with variable mass using continuous constant acceleration. We have derived the equations of motion of the spacecraft after using the space-time transformations of Meshcherskii. The AEPs have been created by cancelling the gravitational and centrifugal forces with the constant continuous low-thrust at the non-equilibrium points. The positions of these AEPs will depend not only on magnitude but also on the constant directions of the low-thrust acceleration. We have analyzed the linear stability of the AEPs and found that all the AEPs are unstable. Finally, we have drawn the zero velocity curves (ZVCs) to determine the possible regions of motion in which the spacecraft is free to move
Relationships and spatial structure of soil physical properties in a ten-year corn-cotton rotation field
No full textThis study quantified the relationships between soil, textural, and hydraulic properties at the field-scale for a conventional tilled Memphis silt loam that had undergone a 10-year corn and cotton rotation and described their spatial variability. Composite soil samples collected from the plow layer at 272 nodes on 15 x 15 m grids were analyzed for texture and bulk density. These values were used as pedotransfer functions to predict unsaturated (Ko) and saturated hydraulic (Ks) conductivities as well as the van Genuchten curve shape parameters α and n. Regression analyses quantified relationships between the measured and model predicted soil properties. While correlations between textural and model predicted soil properties including bulk density were significant (p\u3c0.05), those between sand and clay, clay and n, clay and α were not. Sand and silt appeared to be better predictors of soil hydraulic conductivity and the van Genuchten curve shape parameters for the soil investigated. Spatial dependence was strong for sand, silt, bulk density, Ko, α and n, and moderate for clay and Ks
Performance of Multi-Radar Multi-Sensor (MRMS) product in monitoring precipitation under extreme events in Harris County, Texas
No full textWith an increase in intensity and frequency of extreme precipitations as a result of climate change, it is necessary to develop effective strategies for emergency flood management plan. It is critical to integrate the use of high-resolution hydro-meteorological data (e.g., precipitation) as input for hydrologic modeling to accurately predict and reduce the negative impact of floods. The Multi-Radar Multi-Sensor (MRMS) system has been developed by the National Severe Storms Laboratory (NSSL) to produce high-resolution spatio-temporal precipitation data. While the MRMS data are available at relatively high spatial (1 km) and temporal (2 min) resolutions across the continental United States (CONUS), MRMS\u27s accuracy in measuring actual precipitation needs to be investigated across some urban areas such as Harris County, TX. Therefore, the objectives of this study are to evaluate i) the performance of the MRMS system compared to other precipitation products (rain gauge network, Multisensor Precipitation Estimator (MPE)) at different spatial (5, 10, 15, 30 km) and temporal aggregations (5, 10,15, 30, 60 min) during four major flooding events of May 2015 (Memorial Day flood), April 2016 (Tax Day Flood), August 2017 (Hurricane Harvey), and September 2019 (Tropical Storm Imelda) in Harris County, Texas; and ii) the effects of temporal and spatial aggregation scales on the performance of the MRMS system using a suite of statistical parameters. Point-to-grid comparisons were conducted between 142 rain gauges and MRMS system data during four extreme flood events. Overall, the MRMS system captured precipitation reasonably well with a coefficient of determination (R2) of 0.78, correlation coefficient (CC) of 0.88, root mean square error (RMSE) of 1.21 mm, critical success index (CSI) of 0.65, probability of detection (POD) of 0.98, and false alarm ratio (FAR) of 0.34 over Harris County at 15 min and 15 km temporal and spatial resolutions. The results indicate that MRMS product tends to underestimate higher precipitation rates and overestimate light precipitation. Coarser temporal resolutions from 5 min to 1 h resolved some of the overestimation issues. Temporal aggregation increased R2, CC, CSI, and error variances and decreased FAR. However, increasing spatial resolution from 1 to 30 km increased R2, CC, and CSI and reduced RMSE and FAR. A comparison of MPE QPE and MRMS products at hourly temporal resolution with gauge observations showed that both products estimate rainfall accurately for the four events. Still, on average, MRMS product has a slightly better agreement with rain gauge observations at 1-hr temporal resolution
The Impact of the Livestock Friendly Designation on the Nebraska Cattle Industry: A Difference-in-Difference with Staggered Treatment Analysis
No full textIn 2003, the Nebraska Legislature enacted the Livestock Friendly County designation program to promote the livestock industry in the state. Forty-nine of the state\u27s 93 counties received the designation at staggered years. Our paper estimates the causal effect of the program on the state\u27s cattle industry using a fixed effect difference-in-difference model that accounts for self-selection and staggered designation. Results indicate that the program does not appear to have a statewide effect on livestock expansion, but it is effective in some crop reporting districts. We offer some hypotheses on why this may be the case and draw some policy implications
Release or Denial: Evaluating the Roles of Emotion and Risk in Parole Decisions
No full textParole boards often incorporate numerous factors when making release decisions. These factors are typically related to the inmates’ case files. However, in some instances, parole boards’ decisions are influenced by factors outside of the case files, sometimes referred to as extra-legal factors. According to the emotion as social information model, emotion can communicate specific messages to others, and in this case, parole board members might unknowingly incorporate their own emotions and inmates’ emotional displays into their decisions. The current study examines the role of parole board member and inmate emotional expressions as predictors of parole release decisions. Parole hearings were coded for emotion, parole board and inmate gender, supporter presence, and risk scores. Overall, risk scores and parole board members’ emotions predicted release decisions. Higher risk scores were associated with a lower likelihood of release, and inmates’ negative emotion was related to a lower likelihood of release. Implications are discussed
(R1468) Global Analysis of an SEIRS Model for COVID-19 Capturing Saturated Incidence with Treatment Response
Get PDFIn this work, a new SEIRS model with saturated incidence rate and piecewise linear treatment response is proposed to describe the dynamics of COVID-19. It is assumed that the treatment response is proportional to the number of infected people as long as the incidence cases are within the capacity of the healthcare system, after which the value becomes constant, when the number of confirmed cases exceeds the carrying capacity of the available medical facilities. Thus, the basic reproduction number of the model is obtained. It is proved that the disease-free equilibrium is globally asymptotically stable when the basic reproduction number is less than a critical value. Moreover, sufficient conditions are obtained to guarantee the local and global stability of the equilibrium points of the model. The numerical analysis reveals that multiple endemic equilibria may exist even when the basic reproduction number is less than one, and some interesting dynamics can be observed when the treatment parameter and immunity waning rate are varied
(R1454) On Reducing the Linearization Coefficients of Some Classes of Jacobi Polynomials
Get PDFThis article is concerned with establishing some new linearization formulas of the modified Jacobi polynomials of certain parameters. We prove that the linearization coefficients involve hypergeometric functions of the type 4F3(1). Moreover, we show that the linearization coefficients can be reduced in several cases by either utilizing certain standard formulas, and in particular Pfaff-Saalschütz identity and Watson’s theorem, or via employing the symbolic algebraic algorithms of Zeilberger, Petkovsek, and van Hoeij. New formulas for some definite integrals are obtained with the aid of the developed linearization formulas
Analysis of Means (ANOM) Concepts and Computations
Get PDFThe classical Analysis of Means (ANOM) is a statistical inferencing procedure and visualization tool to analyze means from experiments with fixed effects. It can serve as an alternative to the Analysis of Variance (ANOVA) procedure that has distinct advantages when determining which effects contributed to an overall test’s significant result. ANOM has been extended to handle numerous situations including robust procedures involving ranks. More recent advancements of this procedure allow one to handle both random, and mixed effect models. In this work, we discuss the recent developments on ANOM methods that are useful in practice, provide examples that illustrate their effectiveness, and discuss logistical issues with post hoc testing
On Digital Metric Space Satisfying Certain Rational Inequalities
Get PDFIn this paper, we have established some new results by extending some existing theorems in the setting of Digital Metric Space. We also proved some results in Digital Metric Space which were established earlier in the context of Complete Metric Space by different authors
Hamacher Operations of Fermatean Fuzzy Matrices
Get PDFThe purpose of this study is to extend the Fermatean fuzzy matrices to the theory of Hamacher operations. In this paper, the concept of Hamacher operations of Fermatean fuzzy matrices are introduced and some desirable properties of these operations, such as commutativity, idempotency, and monotonicity are discussed. Further, we prove DeMorgan’s laws over complement for these operations. Furthermore, the scalar multiplication and exponentiation operations of Fermatean fuzzy matrices are constructed and their algebraic properties are investigated. Finally, some properties of necessity and possibility operators of Fermatean fuzzy matrices are proved