New Set Of Variables Research Articles

Low-Thrust Trajectory Optimization with Averaged Dynamics Using Analytical Switching Detection

This paper presents an efficient indirect optimization method for the time- and fuel-optimal low-thrust many-revolution transfers with averaged dynamics. Compared with the previous indirect method, the proposed method involves a new set of variables and several near-optimal control laws to formulate the two-point boundary value problem based on three practical assumptions. Then, the costate transformations between two reference frames are first derived with respect to the the corresponding Eulerian angles, such that the switching function can be expressed with a six-degree polynomial function and the number of parameters used to determine the energy-optimal solutions is reduced to 6. Finally, a neural network is trained to generated the initial guesses, and the solution algorithms for solving the time- and fuel-optimal problem are formulated. Numerical simulations demonstrate that the convergence ratio of initial guesses is higher than 98%, the proposed assumptions are reasonable for guaranteeing the near optimality, and the presented method can obtain convergent solutions within tenths of a second for the Earth- and moon-centered external/interior transfers considering the shadow J2 and third-body perturbations.

A multi-subsystem collaborative Bi-LSTM-based adaptive soft sensor for global prediction of ammonia-nitrogen concentration in wastewater treatment processes

Ammonia-nitrogen concentration is a key water quality indicator, which reflects changes in pollutant components during wastewater treatment processes. The timely and accurate detection results contribute to optimizing control and operational management of wastewater treatment plants (WWTPs), but current detection methods only focus on the effluent location. This paper proposes a multi-subsystem collaborative Bi-LSTM-based adaptive soft sensor to achieve the global prediction of ammonia-nitrogen concentration. Firstly, the wastewater treatment process is divided into several independent subsystems depending on the reaction mechanism, and the variable selection is performed using mutual information. Subsequently, the bidirectional long short-term memory network (Bi-LSTM) is employed to construct a model for predicting ammonia-nitrogen concentration within each subsystem, and the outputs between neighboring subsystems are incorporated as a set of new variables added into the training dataset to strengthen their connection. Finally, to address performance degradation caused by environmental factors, a probability density function (PDF)-based dynamic moving window method is proposed to enhance the robustness. The effectiveness and superiority of the proposed soft sensor are validated in the Benchmark Simulation Model no. 1 (BSM1). The experimental results demonstrate that the proposed soft sensor can accurately predict the global ammonia-nitrogen concentration in the face of different weather conditions including sunny, rainy, and stormy days. This study contributes to the stable operation of WWTPs with higher treatment efficiency and lower economic costs.

MHD nanofluid flow with energy transfer over a porous stretching surface by using a second-grade fluid model

The main attention of this research is to examine the nature of the flow behavior of nanofluids and energy transfers past an expanding sheet with second-grade fluid model. The system is also situated in an absorbent area, which affects the effects of heat and mass transport and chemical reaction. The numerical calculations and visualization for various flow parameters are performed using a finite difference code that is developed in the built-in bvp4c solver scheme of MATLAB. This involves adopting a set of new variables to change the character of the governing equations of this study. To the best of the authors’ knowledge, many authors have contributed to this field, but they do not take into account the above fluid model associated with the energy transfers with the influences of Brownian motion, thermophoresis effect, and chemical reaction parameters, etc., in their study. Major findings of this study is to achieve a higher amount of thermal transference using the physical parameters, such as magnetic, visco-elastic, thermophoresis, and Brownian motion parameters, etc. Also, using smaller values of the magnetic parameter can be an effective way to minimize the impact of drag force of the fluid at the surface. The considering fluid model has multifarious industrial applications, such as food and cosmetic industry and pharmaceutical and biomedical industry, etc., due to its versatile rheological characteristics.

Comparative Numerical Analysis for the Error Estimation of the Fluid Flow over an Inclined Axisymmetric Cylinder with a Gyrotactic Microbe

The numerical investigation of bioconvective nanofluid (NF) flow, which involves gyrotactic microbes and heat and mass transmission analysis above an inclined extending axisymmetric cylinder, is presented in this study. The study aims to investigate the bioconvection flow of nanofluid under the influence of heat sources/sinks. Through proper transformation, all partial differential equations are transformed into a non-linear ODE scheme. A new set of variables is presented in the directive to get the first-order convectional equations and then solved numerically using bvp4c MATLAB, embedded in the function. The proposed model is validated after calculating the error estimation and obtaining the residual error. The influence of various factors on the velocity, energy, concentration, and density of motile microorganisms is examined and studied. The analysis describes and addresses all physical measures of concentration such as Skin Friction (SF), Sherwood number, the density of motile microorganisms, and Nusselt number. To validate the present study, a comparison is conducted with previous studies, and excellent correspondence is found. In addition, the ND-Solve approach is utilized to confirm the bvp4c. The mathematical model is confirmed through error analysis. This study provides the platform for industrial applications such as cooling capacity polymers, heat exchange, and chemical production sectors.

Detection of Torque Teno virus in IRAQI hemodialysis patients

Some data suggest that the liver is being affected by a new set of variables, and one of them is the Torque Teno virus, which is widespread in the liver other than the well-known hepatitis A-E viruses. Dialysis patients with hepatitis C virus (HCV) and those who are not HCV infected were compared to healthy persons using the nested PCR method to evaluate the extent of the viral dissemination in the Iraqi dialysis population and how it affects infection severity. The research began in 2021 until the end of 2022. Blood was drawn from 35 HCV-infected dialysis patients, 35 HCV-uninfected dialysis patients, and 20 healthy individuals. Immunological (ELISA), chemical and hematological testing findings were reported. In this study, molecular detection by nested PCR was performed to identify the Torque Teno virus. PCR identifies the Torque Teno virus in hemodialysis patient blood samples. The infection rate was 0% in healthy persons, 14.29% in dialysis patients without HCV (5 out of 13), and 20% in dialysis patients with HCV (7 out of 13). This research found a greater prevalence of the Torque Teno virus in HCV patients than in dialysis patients without HCV infection, and the detection of TTV by PCR technique was 100% for sensitivity specificity. This research demonstrated non-significant differences between Torque Teno virus infection and liver enzymes in hemodialysis patients. Keywords: Torque Teno virus, hemodialysis, Anelloviridae

A Qualitative Investigation on Risk Management Implementation in the Malaysian Public Sector

"This study aimed to examine the implementation of risk management in the public sector and, subsequently, identify the components of risk management that best fit the public sector. Interviews were conducted with 26 participants from nine government agencies to determine the Malaysian government’s risk management and internal control processes. As a result, a new set of variables was identified for the public sector. These elements are the establishment of risk management in the government sector, the voluntary implementation of risk management, understanding risk management and internal control, the importance of risk management and internal control, the risk management process for the public sector, risk identification and investigation, understanding the risk management framework in the public sector, and the role of a consultant in risk management. This study contributed to the public sector by identifying potential aspects that may be crucial in ensuring the success of the early stages of risk management implementation. The outcomes of this study may benefit the public sector through an improved understanding of how to undertake risk management to ensure the success of risk management in Malaysia."

Neoclassical transport in strong gradient regions of large aspect ratio tokamaks

We present a new neoclassical transport model for large aspect ratio tokamaks where the gradient scale lengths are of the size of the ion poloidal gyroradius. Previous work on neoclassical transport across transport barriers assumed large density and potential gradients but a small temperature gradient, or neglected the gradient of the mean parallel flow. Using large aspect ratio and low collisionality expansions, we relax these restrictive assumptions. We define a new set of variables based on conserved quantities, which simplifies the drift kinetic equation whilst keeping strong gradients, and derive equations describing the transport of particles, parallel momentum and energy by ions in the banana regime. The poloidally varying parts of density and electric potential are included. Studying contributions from both passing and trapped particles, we show that the resulting transport is dominated by trapped particles. We find that a non-zero neoclassical particle flux requires parallel momentum input which could be provided through interaction with turbulence or impurities. We derive upper and lower bounds for the energy flux across a transport barrier in both temperature and density and present example profiles and fluxes.

Double-diffusive convection in viscous flow over a rotating porous and moving disk

This paper presents the double-diffusive convection in the flow of viscous fluid over a heated, rotating, porous and moving disk. All the field quantities, defined at the surface of such disk, are nonuniform and nonlinear, therefore, the boundary conditions of the simulated problem are nonhomogeneous and variable. A set of new variables is found and it has simplified the system of six PDE's along with the boundary conditions into a system of coupled ODE's of boundary value type. The system of nonlinear, coupled and boundary value ODE's has some nine dimensionless parameters, whereas, effects of these numbers have been seen on all field variables, tangential and surface shear stresses and rates of heat and mass transfer. The present simulations have generalized the concept of rotating disk flows in the sense that the three components of velocity, associated with the disk, are taken nonuniform and nonlinear, whereas, the other thermodynamic properties, specified at the surface of the disk, also have the nonlinear nature. In this investigation, we focused on weak and strong assisting and opposing flows of liquids and gases over a rotating disk in the presence of stretching, shrinking, injection and suction velocities. Each component of velocity is effectively (slightly) enhanced with the variation of and in case of assisting (opposing) flow in the presence of stretching/shrinking and injection/suction. Moreover, similar behavior of the other field variables and quantities of physical interests has been noticed. Thin momentum, thermal and concentration boundary layers are appeared in some cases, which are clearly demonstrated in graphs in special situations.

Contextuality and Informational Redundancy

A noncontextual system of random variables may become contextual if one adds to it a set of new variables, even if each of them is obtained by the same context-wise function of the old variables. This fact follows from the definition of contextuality, and its demonstration is trivial for inconsistently connected systems (i.e., systems with disturbance). However, it also holds for consistently connected (and even strongly consistently connected) systems, provided one acknowledges that if a given property was not measured in a given context, this information can be used in defining functions among the random variables. Moreover, every inconsistently connected system can be presented as a (strongly) consistently connected system with essentially the same contextuality characteristics.

Upgrading isovist models by introducing a new set of variables based on the position of the open edges

Upgrading isovist models by introducing a new set of variables based on the position of the open edges

News-based sentiment: can it explain market performance before and after the Russia–Ukraine conflict?

PurposeThe purpose of this paper is to analyze the market response of the aerospace and defense industry and the airline industry to the ongoing conflict between Ukraine and Russia based on the sentiments from war-related news articles over the period from October 2021 to June 2022.Design/methodology/approachThe study uses the news article database of Global Database of Events, Languages and Tone (GDELT) to create a new set of variables that reflect the news sentiment regarding war and conflict. By investigating the newly created sentiment variables in combination with traditional event study methodology, the authors seek to find out whether sentiment indicators can be helpful to rationalize the evolution of the different stock markets before and after the conflict.FindingsThe authors' results point out a significant negative impact of the war on the airline market and a positive impact on the defense market. The authors' study also introduces a new set of war-related news-based sentiment variables that is significant to explain the evolution of the two markets before and after the war. The relationships between this study's new set of variables and the performance of the two markets are also proven to be significantly impacted by the invasion.Originality/valueTo the best of the authors' knowledge, this is the first research to use the news sentiment related to the topic of war and conflict to explain the market movement of different industries during the Ukraine invasion.

Dynamical systems of cosmological models for different possibilities of G and rho _{Lambda }

The present paper deals with the dynamics of spatially flat Friedmann–Lemaître–Robertson–Walker (FLRW) cosmological model with a time varying cosmological constant Lambda where Lambda evolves with the cosmic time t through the Hubble parameter H, that is, Lambda (H). We use the expression of Lambda (H) in the form of Taylor series with respect to H keeping only the even powers of H because of the general covariance of the effective action of quantum field theory in a curved background. Dynamical systems for three different cases based on the possibilities of gravitational constant G and the vacuum energy density rho _{Lambda } have been analysed. In Case I, both G and rho _{Lambda } are taken to be constant. We analyse stability of the system by using the notion of spectral radius, behavior of perturbation along each of the axes with respect to cosmic time and Poincaré sphere. In Case II, we have dynamical system analysis for G=hbox {constant} and rho _{Lambda } ne constant where we study stability by using the concept of spectral radius and perturbation function. In Case III, we take G ne constant and rho _{Lambda } ne constant where we introduce a new set of variables to set up the corresponding dynamical system. We find out the fixed points of the system and analyse the stability from different directions: by analysing behaviour of the perturbation along each of the axes, Center Manifold Theory and stability at infinity using Poincaré sphere respectively. Phase plots and perturbation plots have been presented. We deeply study the cosmological scenario with respect to the fixed points obtained and analyse the late time behavior of the Universe. The effective equation of state parameter omega _{eff}, total energy density Omega _{tt} are also evaluated at the fixed points for each of the three cases and these values are in agreement with the observational values in Aghanim et al. (Astron Astrophys 641(A6): 2020, 2018). We have also presented the EoS parameter for dark energy sector omega _{de}(z_{r}), the Hubble parameter H(z_{r}) and the deceleration parameter q(z_{r}) as functions of redshift z_{r} for all the three cases and their plots over redshift are also provided. We analyse the quintessence-like, phantom-like or the purely cosmological-constant type dark energy, etc behavior when the EoS approaches the fixed point value near -1. The present values of omega _{de}(z_{r}), H(z_{r}), q(z_{r}) and z_{rt} have been tabulated in Table 4 and they fall within the range of cosmological observations. The transition redshift value (z_{rt}) for each of the three cases have also been evaluated. In each of the cases the developed model agrees with the fact that the Universe is in the epoch of accelerated expansion for suitable values of free parameters chosen. The developed cosmological models associated with each of the three cases have a deep connection with the accelerated expansion phenomena of the evolving Universe.

The Existence and Uniqueness of Global Admissible Conservative Weak Solution for the Periodic Single-Cycle Pulse Equation

This paper is devoted to the study of the existence and uniqueness of global admissible conservative weak solutions for the periodic single-cycle pulse equation. We first transform the equation into an equivalent semilinear system by introducing a new set of variables. Using the standard ordinary differential equation theory, we then obtain the global solution to the semilinear system. Next, returning to the original coordinates, we get the global admissible conservative weak solution for the periodic single-cycle pulse equation. Finally, given an admissible conservative weak solution, we find a equation to single out a unique characteristic curve through each initial point and prove the uniqueness of global admissible conservative weak solution without any additional assumptions.

Generalized Clebsch Variables for Compressible Ideal Fluids: Initial Conditions and Approximations of the Hamiltonian

Clebsch variables provide a canonical representation of ideal flows that is, in practice, difficult to handle: while the velocity field is a function of the Clebsch variables and their gradients, constructing the Clebsch variables from the velocity field is not trivial. We introduce an extended set of Clebsch variables that circumvents this problem. We apply this method to a compressible, chemically inhomogeneous, and rotating ideal fluid in a gravity field. A second difficulty, the secular growth of canonical variables even for stationary states of stratified fluids, makes expansions of the Hamiltonian in Clebsch variables problematic. We give a canonical transformation that associates a stationary state of the canonical variables with the stationary state of the fluid; the new set of variables permits canonical approximations of the dynamics. We apply this to a compressible stratified ideal fluid with the aim to facilitate forthcoming studies of wave turbulence of internal waves.

GENDER DIVERSITY, FINANCIAL EXPERTISE, CEO DUALITY AND FIRM PERFORMANCE

This study aims to examine gender diversity, financial expertise, CEO duality on company performance in Indonesia. The author uses panel data testing with three years starting from 2018 - 2020 using STATA software. Panel data testing was carried out by conducting three tests: common effect model, fixed-effect model, and random effect model, including the model selection test, namely the Chow test, the Hausmann test, and the Breusch pagan LM test. The author also tested by conducting factor analysis with principal component analysis to carry out a linear transformation to change from most of the original variables used (ROA & ROE), and make them correlated into a new set of variables (firm performance). The results of this study conclude that the gender diversity variable has no effect on firm performance, but the variables of financial expertise and CEO duality affect firm performance.

Global conservative solution for a dissipative Camassa-Holm type equation with cubic and quartic nonlinearities

This paper is devoted to the global conservative solutions of a dissipative Camassa-Holm type equation with cubic and quartic nonlinearities. We first transform the equation into an equivalent semilinear system by introducing a new set of variables. Using the standard ordinary differential equation theory, we then obtain the global solutions of the semilinear system. Returning to the original variables, we get the global conservative solution of the equation. Finally, we show that the peakon solutions of the equation still conserve in .

Do the Effective Tax Incentives Reduce Tax Revenues? Investigating the Paradox of Corporate Income Tax in Serbia

The aim of this paper is to examine the impact of tax incentives as determinants of economic development on revenues from corporate income tax in Serbia. The study uses data from secondary resources of the Ministry of Finance for the period 2007–2018 by employing regression and factor analysis. The research includes 10 tax incentives that were used in Serbia in the analyzed period. The methodology of empirical verification involves the implementation of correlation analysis, regression analysis and factor analysis. We opted for the application of Principal Component Analysis (PCA) because this method extracts the important data in order to present a set of new variables called main components. The model obtained in this way formed the determined components of tax incentives as independent variables. The model considers tax incentives grouped into four components. The results of empirical research indicate that there is a positive impact of certain tax incentives on revenues from corporate income tax and proved the paradox of tax collection initiated by tax incentives. The model proved that tax incentives explaining the first component had a positive effect on revenues from corporate income tax. Namely, the incentives for investments, incentives exempting the taxpayer from paying corporate income tax for work training, professional rehabilitation and employment of disabled persons, as well as a reduction based on the elimination of double taxation have a positive effect on revenues from corporate income tax. The positive impact of tax incentives can be explained by their effectiveness. The results show that tax incentives policy must be defined in detail for the purpose of achieving the economic and social goals.

Auto-correlations and long time memory of environment sound: The case of an Urban Park in the city of Milan (Italy)

We investigate the possible presence of ‘long time’ memory in the auto-correlations of biophonic activity of environment sound. The study is based on recordings taken at two sites located in the Parco Nord of Milan (Italy), characterized by a wooded land, rich in biodiversity and exposed to different sources and degrees of anthropogenic disturbances. The audio files correspond to a three-day recording campaign (1-min recording followed by 5-min pause), from (17:00) April 30 to (17:00) May 3, 2019, which have been transformed into ecoacoustic indices time series. The following eight indices have been computed: Acoustic Complexity Index (ACI), Acoustic Diversity Index (ADI), Acoustic Evenness Index (AEI), Bio-acoustic Index (BI), Acoustic Entropy Index (H), Acoustic Richness index (AR), Normalized Difference Soundscape Index (NSDI) and Dynamic Spectral Centroid (DSC). We have grouped the indices carrying similar sound information by performing a principal component analysis (PCA). This allows us to reduce the number of variables from eight to three by retaining a large (≳80%) variance of the original variables. The time series corresponding to the reduced set of new variables have been analyzed, and both seasonal and possible long term trend components have been extracted. We find that no trends are present, i.e. the resulting time series are stationary, and the auto-correlations of the three selected PCA dimensions and associated residuals (obtained after extracting the seasonal components) can be determined. The calculations reveal the presence of a “memory” of few (≲5) hours long in the environment sound, for the two sites considered, which is quantified by the Hurst exponent, H. For Site1, we find an overall effective Hurst exponent, Hdim≃0.88, for all three dimensions, and Hres≃0.75 for the residuals. For Site2, the exponents are slightly smaller, amounting to 0.80 and 0.60, respectively. We attempt to correlate the Hurst exponents with a quality index obtained from an aural survey, aimed at determining the sound components, such as biophonies, technophonies and geophonies, at the two sites. We conclude that the higher the Hurst exponents, the higher are the periodic-structured sounds, corresponding to stronger long-term biophonic activity. We find that Site1 has a more structured environment sound than Site2, also consistent with the major presence of tall trees surrounding the location of the acoustic sensor at the former.

Einstein-æther scalar–tensor cosmology

We propose an Einstein-æther scalar–tensor cosmological model. In particular, in the scalar–tensor Action Integral, we introduce the æther field with æther coefficients to be functions of the scalar field. This cosmological model extends previous studies on Lorentz-violating theories. For a spatially flat Friedmann–Lemaître–Robertson–Walker background space, we write the field equations which are of second order with dynamical variables the scale factor and the scalar field. The physical evolution of the field equations depends upon three unknown functions which are related to the scalar–tensor coupling function, the scalar field potential, and the æther coefficient functions. We investigate the existence of analytic solutions for the field equations and the integrability properties according to the existence of linear in the momentum conservation laws. We define a new set of variables in which the dynamical evolution depends only upon the scalar field potential. Furthermore, the asymptotic behavior and the cosmological history are investigated where we find that the theory provides inflationary eras similar to that of scalar–tensor theory but with Lorentz-violating terms provided by the æther field. Finally, in the new variables, we found that the field equations are integrable due to the existence of nonlocal conservation laws for arbitrary functional forms of the three free functions.

Urea treatment decouples intrinsic pH control over N2O emissions in soils

Soil N2O emission potential is commonly investigated under idealized denitrifying conditions (e.g. nitrate-N supplied and anaerobic soil), with pH commonly identified as a major determinant of N2O emission potential. However, under urine patch conditions in grazed pastures soils a more complex series of abiotic and biotic factors may influence emissions due to the complex N transformations that occur following urea hydrolysis. These transformations may decouple native and/or expected controls of N2O emissions encountered under classic denitrifying conditions. Here, we tracked O2, CO2, NO, N2O and N2 emissions from urine amended soils (i.e. simulating a urine patch) to determine putative controls of N2O emissions within 13 different pasture soils from northern (Ireland) and southern hemispheres (New Zealand). Incubations were performed under aerobic conditions±artificial urine (13.3 mg N vial−1) equivalent to field ruminant urine deposition rates of 1000 kg N ha−1. Results revealed that pH was not an important regulator of the emission ratio (N2O/(NO + N2O + N2)) in urine amended soils. Within urine affected soils, a new set of variables emerged as regulators of N2O emissions, likely due to the unique environment created within this system. We show that urine results in decoupling of the initial soil pH control of the emission ratio allowing other regulators such as nitrite to dominate. In addition, we observed that the emission ratio of N2O increased linearly with the rate of N- gas loss (NO + N2O + N2 μmol N h−1), O2 consumption was positively associated with ammonia oxidising bacteria (AOB) and that the production of NO and N2O were also enhanced under urine conditions.