Volume 23 – Issue 1

In this study, Darboux vector W ̅ of the natural lift curve α ̅ for the given curve α is calculated in terms of the types of curves in Minkowski space. Then striction lines, distribution parameters, Gaussian and mean curvatures of ruled surface pairs generated by the Darboux vector of the natural lift curve have been examined. Furthermore, some examples are given to support the main results.

In this study, using both Hölder’s integral inequality and Hölder-İşcan integral inequality, some inequalities of Hermite Hadamard type obtained for multiplicatively preinvex P-functions are given. Afterwards, the result obtained with Hölder-İşcan inequality has been shown to be better than that obtained with Hölder’s integral inequality.

In the present work we give an extension of (p,q)- analysis. As an extension of (p,q)-analysis, the (r,p,q)-analysis is introduced. We define some elementary concepts of this analysis such as (r,p,q)-numbers, (r,p,q)-derivative, (r,p,q)-exponential functions, (r,p,q)-antiderivative and (r,p,q)-integral. We obtain some properties of the polynomial (x – a)n (r,p,q)-Taylor formula, (r,p,q)-binomial coefficients, divided differences and some relations between (r,p,q)-derivative, (r,p,q)-exponential functions, (r,p,q)-integral and finally, the fundamental theorem of (r,p,q)-analysis are examined in details.

In this paper, we define osculating curves according to the extended Darboux frame (ED-frame), in Euclidean 4-space. Then, according to Case 1 and Case 2 ED-frame fields, the necessary and sufficient condition for a unit speed curve lying on the hypersurface to be congruent to an osculating curve is obtained. For these necessary and sufficient conditions, the solutions of the differential equations have been investigated. Finally, an application has been made on the subject.

In this article, firstly, the intersection of two ruled surfaces corresponding to two different curves on S_1^2 is investigated. The conditions for the intersection of these ruled surfaces in R_1^3 are expressed by theorems with bivariate functions. Then, the intersection of two ruled surfaces corresponding to two different curves on H^2 is examined. Similarly, the conditions for the intersection of these ruled surfaces in R_1^3 are shown by some illustrative theorems with bivariate functions. Finally, some examples are given to support the main results.

In this paper, we present the evolutions of the ruled surfaces constructed by the tangent, normal-like, and binormal-like vector fields of a polynomial space curve. These evolutions of the ruled surfaces depend on the evolutions of their directrices using the Flc (Frenet like curve) frame along a polynomial space curve. Therefore, the evolutions of a polynomial curve are expressed in the first step of this study. Then, some geometric properties of the special ruled surfaces are investigated and examples of these surfaces are given and their graphics are drawn using the Mathematica 9 program.

We study the nonparametric local linear estimation of the conditional hazard function of a scalar response variable given a functional explanatory variable, when the functional data are α-mixing dependency and we give the uniform almost complete convergence with rates of this function.

This research article presents a new Pranav power series class of distributions which is obtained by compounding one parameter Pranav and power series distributions. Various special cases of the new model have been unfolded. Numerous statistical properties of the proposed model are investigated including closed-form expressions for the density function, cumulative distribution function, survival function, hazard rate function, the moments of order statistics and MLEs. Finally, the flexibility and potentiality of the PPS distribution has been demonstrated by means of two real life data sets.

The author’s last two papers concerned the study of arithmetic functions related to the greatest common divisor. In the present paper, similarly to the two previous papers we will define new multiplicative arithmetic functionsrelated to the least common multiple and we will study several interesting properties of them. Also, we will discuss the values of two special functionsof them at perfect numbers.

In this study, considering two different curves on the unit dual sphere, 〖DS〗^2, we investigate the intersection of two different ruled surfaces in R^3 by using E. Study mapping. The conditions for the intersection of these ruled surfaces in R^3 are expressed by theorems with bivariate functions. Finally, some examples are given to support the main results.

In this study we give the structure of the motion RMM with the spherical curve orbit by using rotation minimizing frames (RMF). Further, quaternionic helices and their characterizations of being CCR curve are given with the help of unit quaternions which are related spherical frame motion.

In order to present a new estimation approach for multi-parameter distributions without a mean or for heavy tailed distributions, in which the L-moments method proposed by Gumbel, (1960), is invalid due to the absence of theoretical L-moments, Trimmed L-moments were first introduced by Elamir and Seheult (2003). In this paper, a new estimation method based on multi-parameter copulas’ Trimmed L-moments is proposed with a simulation study. The consistency and the asymptotic normality of the new estimator also established.

The phenomenon of simultaneous left and right double truncation appears in a variety of fields, sush as in medical research. The problem of estimating the mode function for this type of data has not been addressed in the statistical literature. In this paper, we propose a new kernel estimator of the mode in the framework of randomly and doubly truncated model. We establish the strong consistency with a rate for the proposed estimate, and state its asymptotic normality. A simulation study is carried out to illustrate and evaluate the finite sample behavior of the proposed estimator.

Let be the vector spaces and V_i^* be their dual spaces for 1≤i≤r . In this paper, (V_1×V_2×…×V_r )^*≅V_1^*×V_2^*×…×V_r^* is examined. Furthermore, the dual map F^* and the adjoint map F^’ of the r-linear map F:V_1×V_2×…×V_r→W are defined and for their matrices, the equality [F^* ]=[F^’ ]=[F ̅ ]^T is found. Analog, the dual map F^* of the
r-variable vector valued linear map F:V_1×V_2×…×V_r→W_1×W_2×…×W_r is defined and for their matrices, the equality [F^* ]=[F ̅ ]^T is true, for the vector spaces V_i and W_i .

The purpose of this study is to define the 2-absorbing intuitionistic fuzzy ideals and 2-absorbing intuitionistic fuzzy primary ideals of commutative semirings, as well as to describe their characteristics. Furthermore, we define the cartesian product of the 2-absorbing intuitionistic fuzzy primary ideals of commutative semirings.

In present paper, we study the properties of the Killing magnetic field of a pseudo null magnetic curve in R_1^3 . We investigate for the T, N and B-magnetic cases of a pseudo null curve. We find the conditions for the Killing magnetic field to be pseudo null and derive the Frenet formulas for this field. Finally, we obtain the conditions for the transformation of the pseudo null curve to its pseudo null Killing magnetic field with equal torsions.

Classical matrix theory for real, complex and hypercomplex numbers is a well-known concept. Is it possible to construct matrix theory over dual-generalized complex (DGC) matrices? The answer to this question is given in this paper. The paper is constructed as follows. Firstly, the fundamental concepts for DGC matrices are introduced and DGC special matrices are defined. Then, theoretical results related to eigenvalues/eigenvectors are obtained and universal similarity factorization equality (USFE) regarding to the dual fundamental matrix are presented. Also, spectral theorems for Hermitian and unitary matrices are introduced. Finally, due to the importance of unitary matrices, a method for finding a DGC unitary matrix is stated and examples for spectral theorem are given.

Plasma electrolytic oxidation method was used to form ceramic coatings on pure Ti substrates, using various aqueous solutions of sodium aluminate (15 g/L and 20 g/L, with or without the addition of NaOH, 2 g/L). The PEO process was carried out at constant time and voltage (300 seconds, 200 V). The ceramic coatings obtained by PEO were investigated by SEM, EDS, XRD, and XPS. Their corrosion behavior has been evaluated as well. The study aimed to understand the role of NaOH in the development of the PEO process and to evaluate the results obtained by short treatments in potentiostatic regime.

Bisphosphonates are used to treat a number of bone related diseases such as osteosarcoma, malignant hypercalcemia, osteomyelitis. Developing novel drug delivery systems may overcome the adverse reactions caused by traditional administration. This study uses a combination of molecular docking studies and correlation techniques between structure – physical and chemical properties to assess how different bisphosphonates (alendronate, risedronate, pamidronate, zoledronate) interact with polydopamine in order to later design new formulations. The structure of polydopamine is still under discussion therefore, its bisphosphonate binding properties have not been completely established. Polydopamine was modeled by repeated docking of tetrameric subunits combined in two ways which led to simple and mixed oligomers. Fingerprint descriptors, namely electronegativity of the OMO/UMO quantum molecular states, were used for the correlation studies. The correlation coefficients suggest that several atom species such as nitrogen and carbon have increased contributions to the formation of both HOMO and LUMO molecular states. The results showed that the most stable complex was obtained with risedronate for both simple and mixed dopamine oligomers (-186.00 kJ/mol and -184.92 kJ/mol).

In 2019, on one of the most important dacian archaeological sites (Ocnița, Vâlcea County, Romania), in a tomb dug into the rock, along with various weapons, ceramics, bones, etc. there was also discovered a fragmentary sica scabbard. As a consequence of the lack of information on solely such iron-made objects, the urgent need to obtain as much information as possible regarding this type of military equipment was mandatory. Thus we applied different characterization methods aimed at obtaining results regarding the inner structure assembly of the scabbard, the chemical composition and the elemental distribution of the material the scabbard was made of, in order to better understand the technique used by the dacian blacksmiths. With the help of optical macroscopy, energy dispersive – X-ray fluorescence spectrometry (EDXRF), X-ray CT scanning, scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) we tried to reconstruct how the scabbard was made, and how it survived until present times.

The main objective of the paper is to demonstrate the functionality and reliability of a hydrokinetic turbine system – a submersible electric generator, suitable for very low watercourses. To achieve this goal, it is necessary to design and build a prototype of a hydrokinetic turbine, coupled with an electric generator with excitation made with permanent magnets. This paper presents an analytical model and a finite element numerical model for estimating the electrical parameters of the generator (voltage, current, power, etc.). The two models were compared, and the results were extrapolated, in the analytical model, for several speed values.

MHD flow past over oscillating vertical plate with variable temperature and mass diffusion through a porous medium in the presence of Hall current effect and chemical reaction is studied here. The MHD fluid model contains partial differential equations of momentum, energy and diffusion equations. The Laplace-transform technique used to find the exact solution of equations involved in this paper. The resultant velocity profile is discussed with the help of graphs drawn for different parameters like, inclination of magnetic field, chemical reaction parameter, phase angle parameter and permeability parameter, and the numerical values Sherwood number have been also tabulated. It is noticed that the values obtained for velocity, concentration and temperature profiles are in concurrence with the actual flow of the unsteady MHD fluid.

Energy consumption continues to rise due to the increase in the quality of human life. On the other hand, production of these energies must be done with the smaller impact on the environment as possible. All these facts are challenging engineers and researchers from this domain to develop new equipments or to improve the efficiency of the energy production equipments. It was proved that in the case of turbine, if a shroud is applied, the efficiency is raised. Given that in this paper is presented a study performed on different geometry of shrouds with different fixing elements. Computational fluid dynamics (CFD) simulations were performed using ANSYS Fluent software. The numerical domain rigorously reproduces an experimental set-up from the laboratory. The rectangular fixing element do not deliver the expected result, instead it decreases the velocity in interest zone. The most important finding is that the velocity of the fluid increases by more than 50% in the most constrained section with convergent-divergent shroud.

The support of prosumers in the countries of the European Union has registered significant growth, especially regarding the energy produced from photovoltaic panels in households or in commercial spaces after 2020. Romania will promote the distributed generation from renewable sources with installed power between 3 kW and 100 kW, the on-grid installations being subsidized through the financial support of the Environmental Fund Administration (3 kW for residential prosumers) with ,,photovoltaic green house,, program and Ministry of Economy, Energy and Business Environment with the ,,Electric Up,, program (between 27 kW – 100 kW power with recharging stations of at least 22 kWp for electric and hybrid electric vehicles for commercial prosumers). This paper proposes an analysis of a commercial prosumer with a specific case study in north Dobrogea in Romania, comprise of a comparative analysis for an integrated 30 kW comercial user with 44 kW charghing station for electric and hybrid electric vehicles installed on the ground, in order to reduce the energy consumption with a management system for the optimal coordination of the energy to the owner’s need, also to see the rentability of the system when it’s a comercial user and the own consumption is higher during the day. The project applies to Romanian legislation and can be used for similar projects considering that in coming years these types of systems will appear.

This paper presents the modelling and control of a flexible manufacturing system with integrated Industry 4.0 concepts using Petri nets. The flexible manufacturing system is composed of 7 workstations that ensure the assembly and disassembly of two types of products on two parallel production processes. The two parallel processes, in-line and in-cell production processes, ensure the assembly of the products and disassembly of the defects with a minimal number of stations. wo types of controls, local and centralized, are implemented in the control of production processes. The local control, based on the PLCs of each station, ensures the control of the assembly process at the workstation level. The centralized control ensures the obtaining of desired results at the level of interaction between the stations and also the implementation of the optimization algorithm results. To better understand and develop the control of the system a Petri net model was developed. Based on the properties of the Petri nets was possible to simulate and verify the assembly process and data flow inside the flexible manufacturing system. The developed model also ensures no bottlenecks at the data transmission and processing of the production information from the client to the production hardware.

The present paper is part of a larger project whose purpose is to develop a new hydrokinetic turbine-generator assembly, suitable for very low head water courses. It presents the experimental results of a turbine–generator physical model, installed on the tailrace of Mihailesti Hydropower Plant. In order to carry out the measurements, a floating structure and an anchoring system was installed on the power plant tailrace. This system also allowed the translation of the assembly between the two shores. A first set of measurements followed the water velocity and depth in the channel at various load values of the hydropower plant units, in order to determine the proper conditions for testing the model. The turbine gives the possibility of blades adjustment at three different angles, 0, 9 and 14 degrees respectively. Therefore, a set of measurements has been performed for each position of the blades. The measured parameters were the electric parameters of the generator such as voltage, current and the power variation with rotation speed. For the blades adjustment of 9 degrees and 1.76 m/s water velocity, the generator reached its maximum power of 500 W. The results retrieved will be used for the optimization and design of a new enlarged scale turbine–generator assembly. They will also be used as input data for the numerical modeling of the generator. Also, the exact knowledge of the channel geometry and flow parameters is valuable in studies preceding testing a prototype in the site.