Search

This paper presents a more general method to study the dynamic behavior of a planar mechanism with joints. To do this, Graph Theory is used. A topological description is presented based on which a corresponding graph is attached to any mechanism. This method can be used for both kinematic and dynamic study in the same model, and many of the descriptors used in kinematic analysis can also be used for dynamic analysis. As a final result, the motion equations of the studied mechanical system can be obtained. An application is made to a flap and wing control system of a light sport aircraft. The graph associated with the mechanism first used to determine the field of velocities and accelerations of the mechanism elements is then used to obtain the motion equation for the control system. In this way, Graph Theory proves useful for the parallel study of both the kinematic and dynamic study of such problems.

The primary goal of this research is to present a novel computational intelligence approach of the AI-based Levenberg–Marquardt scheme under the influence of backpropagated neural network (LMS-BPNN) for optimizing MHD ternary hybrid nanofluid using Casson fluid over a porous shrinking sheet in the existence of thermal radiation (Rd) effects. The governing partial differential equations (PDEs) showing the Casson ternary hybrid nanofluid are converted into a system of ordinary differential equations (ODEs) with suitable transformations. The numerical data is constructed as a reference with bvp4c (MATLAB built-in function used to solve a system of ODEs) by varying Casson fluid parameters (β), magnetic field (M), porosity (S), nanoparticle concentrations (ϕ1=ϕ2=ϕ3), and thermal radiation (Rd) effects across all LMS-BPNN scenarios. The numerical data-sheet is divided into 80% of training, 10% of testing, and 10% of validation for LMS-BPNN are used to analyze the estimated solution and its assessment with a numerical solution using bvp4c is discussed. The efficiency and consistency of LMS-BPNN are confirmed via mean squared error (MSE) based fitness curves, regression analysis, correlation index (R) and error histogram. The results show that velocity decreases as β grows, whereas velocity increase as M increases. The concentrations of nanoparticles and thermal radiations have increasing effects on θ0. To comprehend the dependability and correctness of the data gained from numerical simulations, error analysis is a key stage in every scientific inquiry. Error analysis is presented in terms of absolute error and it is noticed that the error between the numerical values and predicted values with AI is approximately 10−6. The error analysis reveals that the developed AI algorithm is consistent and reliable.

In this paper, a novel algorithm for a transient linear circuit analysis based on the Finite Element Technique (FET) was established. The FET procedure allows a straightforward solution for complex electric circuits since it is based on the Finite Element Method (FEM) approach. The developed algorithm allows us to select various types of time integration schemes when forming a local system of equations for a coupled circuit finite element. To illustrate the basic principle of the developed FET-based algorithm and to perform transient analysis, a random coupled linear circuit was analyzed. Numerical solutions obtained using Heun’s and the generalized trapezoidal rule (ϑ-method) integration schemes were compared to the solution obtained by Matlab Simulink software. It was shown that the accuracy of results depends on the employed time integration scheme when performing the FET procedure. It was shown that using Heun’s method as the time integration scheme yields more accurate results than using the ϑ-method time integration scheme.

The main aim of the paper is to study the impact of delay times in a poro-elastic medium using the finite element approach and the three-phase lag thermo-elastic theory. The governing equations were obtained for a three-phase lag model with six delay times. Consideration was given to a one-dimensional application of a poro-elastic half-space. Because of the complex form of the basic equations, the finite element approach was used to solve this problem. Asymmetric and symmetric tensors were used to represent all of the physical quantities. The numerical results were presented in graphical form. The effects of porosity and delays were introduced. Finally, the results were plotted to show the difference between the three-phase delay (TPL) and the Green−Naghdi with and without energy dissipation (GNIII) models.

Nanofluids have great potential due to their improved properties that make them useful for addressing various industrial and engineering problems. In order to use nanofluids on an industrial scale, it is first important to discuss their rheological behavior in relation to heat transfer aspects. In the current study, the flow characteristics of nanofluids are discussed using a mathematical model that is developed by fundamental laws and experimental data. The data are collected in the form of viscosity versus shear rate for different homogeneous ethylene glycol- (EG) based nanofluids, which are synthesized by dispersing 5–20% nanoparticle concentrations of SiO2, MgO, and TiO2 with diameters of (20–30 nm, 60–70 nm), (20 nm, 40 nm), and (30 nm, 50 nm), respectively. The data are fitted into a rheological power-law model and further used to govern equations of a physical problem. The problem is simplified into ordinary differential equations by using a boundary layer and similarity transformations and then solved through the numerical Runge–Kutta (RK) method. The obtained results in the form of velocity and temperature profiles at different nanoparticle concentrations and diameters are displayed graphically for discussion. Furthermore, displacement and momentum thicknesses are computed numerically to explain boundary-layer growth. The results show that the velocity profile is reduced and the temperature profile is raised by increasing the nanoparticle concentration. Conversely, the velocity profile is increased and the temperature profile is decreased by increasing the nanoparticle diameter. The results of the present investigation regarding heat and mass flow behavior will help engineers design equipment and improve the efficacy and economy of the overall process in the industry.

The valve performs an alternating translational motion along its axis of symmetry, which is accompanied by a rotation about its own axis, possibly due the valve body’s cylindrical geometry and due to the conjugate element, the guide, which is also a cylindrically shape body. By ensuring this rotational motion of the valve, a number of advantages are obtained, mainly related to the increase of the operating period of the valve and implicitly of the engine. Following the critical analysis of the current state of research on the valvetrain systems and the rotational motion of the valves, the advantages and the disadvantages of valve rotation during engine operation were established. To this end, it has been established that, in addition to the theoretical approach to the problem, it is necessary to create a virtual model of the valvetrain mechanism to do a thorough analysis of the problem. Based on the model, the influence of the camshaft speed, temperature and lubricating oil pressure were monitored by changing the coefficient of friction, the influence of the cam position relative to the tappet and the influence of the valve spring. In this paper, the authors want to determine the rotational motion characteristics of internal combustion engine valves and to suggest measures that can be taken to ensure valve rotation at all operating modes without the use of auxiliary devices for generating rotational motion.

This work describes a method for synthesis, as well as in vitro antiproliferative and antibacterial investigation of 3-methyl-9′-fluorenespiro-5-hydantoin. The structure of the substituted fluorenylspirohydantoin derivative was verified by UV-Vis, FT-IR, Raman, 1H-NMR and 13C-NMR spectroscopy, and by using a combination of 2D NMR experiments, which included 1H-1H COSY, HMQC and HMBC sequences. The geometry of the compound was optimized by the B3LYP density functional with 6-31G(d) basis set and the 1H and 13C NMR spectra were predicted with the HF/6-31G(d) calculations at the optimized geometry. The anticancer activity of the 3-methyl-9′-fluorenespiro-5-hydantoin was determined in suspension cell lines originating from tumors in humans (WERI-Rb-1). The cytotoxic effect was evaluated by WST-assay (Roche Applied Science). The antimicrobial effect of the compound against Gram-negative, Gram-positive bacteria and the yeast Candida albicans was investigated.

This paper studies the mechanical behavior of high-density polyethylene (HDPE), from which the pipes used for water transport in water supply networks are manufactured. The study was generated by the practical problem of replacing and modernizing a water network of a city with 300,000 inhabitants. Of the numerous problems that have arisen and been solved by the group of researchers, only those referring to the mechanical behavior of the materials used for pipes are presented. HDPE, which is a thermoplastic material, is suitable for manufacturing the pipes used in water supply networks, having many advantages. Data on the mechanical properties of the material of which the pipe and elbow are made is obtained experimentally. The work involved the main steps required to design a water network, but the subject is not exhausted. The stresses in the polyethylene pipe are determined in two cases: buried in the ground and supported in a concrete massif. Thus, by calculation, the advantage offered by the second solution is justified. The crack of the pipes manufactured from HDPE is studied, taking into account the classical model used in the cracking process. A simulation of pipes and elbows cracking was made. The results obtained via MEF are useful for the users of the networks.

Synthesis and characterization of new Pt(II) complexes of cyclohexanespiro-5-(2-thiohydantoin) (L1) and cycloheptanespiro-5-(2-thiohydantoin) (L2) are discussed. The new complexes are studied by elemental analysis, IR, ATR FTIR spectroscopy. The free ligands are investigated by UV-Vis, FT-IR ATR and Raman spectroscopy. The ground-state equilibrium geometries of the ligands L1 and L2 and their complexes with Pt(II) are optimized at the BLYP/CEP-31G theoretical level.

This study presents an automated system for potentiometric determination of free and total cyanide which employs a homogeneous membrane tubular ion-selective electrode. After the electrode is assembled, it is connected to a system composed of 3 three-way solenoid valves, sample line, carrier line, acid stream, and gas diffusion chamber. A Turbo Pascal® computer program, developed specifically for this task, automatically performs all the steps involved in data acquisition and processing. The proposed analytical procedure offers operational simplicity, since detection is performed by a tubular electrode, whose assembly is fast and easy. The system has shown reproducibility (r.s.d. < 0.5%, n=6) and high speed (30 readings/hour); it is efficient for determination of free and total cyanide in waste waters of starch processing plants. The detection limit was 1.2x10-5 and 1.5x10-5 mol L-1, for determination of free and total cyanide, respectively. The linear response range was between 1.2x10-5 and 1.0x10-2 mol L-1 for free cyanide and between 1.5x10-5 and 1.0x10-2 for total cyanide.

A simple flow cell for potentiometric detection is described. It was assembled by making use of two perspex pieces fixed together by means of four screws, and allow the connection of plane membrane conventional electrodes to flow system. Details about its construction are presented. The device performance was evaluated by making use of a cyanide ion-selective electrode. The relative standard deviation was about 0.5% with a detection limit of 8.0 x 10-6 mol CN- dm-3. Under experimental conditions, the linear range was 10-5 to10-2 mol dm-3.