Angle 0o Research Articles

Numerical analysis of heat transfer in annulus composite material at different operation conditions

In this article natural air convection in an inclined annular cage in three dimensions is investigated numerically. This study will examine the impact of the radius ratio of an annulus on heat transfer employing two distinct methods to optimizing effective thermal conductivity: minimizing and maximizing. The annulus is built of graphite/epoxy laminated composite material. There are 12 fins attached to the inner cylinder of the two concentric cylinders that make up the annulus enclosure, which is filled with porous medium. Regarding the annulus's inclination angle “δ”, two scenarios—a horizontal annulus and a vertical annulus—are considered. Constant walls temperature boundary condition and steady state conditions apply to the system with 0.2, 0.3, 0.4 and 0.5 different radius ratio, inclination angle (0o and 90o), and modified Rayleigh number “Ra*” ranged from 10 to 500, The Nusselt number decreased for all parameters as the radius ratio Rr decreased, indicating a wider cold outer cylinder gap. For large values of modified Rayleigh number, the average Nu number ”Nuavg.” decreases with an increase in δ, and increases with a rise in the modified Rayleigh number; for low values of Ra*, δ has no effect. For horizontal, and vertical states “δ=0 o, and 90o respectively, at higher and lower thermal conductivity, the divergence of the average Nusselt is 5.1% and 10%, respectively. In horizontal cylinder adding fins on the inner cylinder is more substantial for due to its impeding effect, and NuL increases with cylinder length. For the outer cold cylinder, a link between Ra* and δ and the average Nusselt number has been established.

Comparison of Compression of Occlusal Splint Materials: Laboratory Mechanical Analysis

Objective: To perform a compression test to fill the gap in the literature, assess the change in the construction angle (0º, 45º, 90º) as well as investigate physical and microstructural characteristics. Theoretical Framework: Comparisons of compression tests of occlusal splint materials printed in 3D are not described in the literature, which makes informed decision making on the choice of materials complicated. Method: The materials printed in 3D using the SLA method were resins. After printing, the materials were submitted to compression (calculating the Poisson coefficient), shore hardness and density tests. Results and Discussion: Dima® Print Ortho achieved the best results in terms of compression strength and maximum deformation in the vertical position (90º) in comparison to the other materials, followed by Self BioPrint Splint Hard, PriZma 3D Bio Splint and Cosmos Splint. Research Implications: Three-dimensional devices through additive fabrication can be used in the treatment of bruxism. The position to obtain greater compression strength is vertically at 90º. Originality/Value: This study contributes to the literature by demonstrating the efficacy of 3D printing of occlusal devices using the resin polymerization method, highlighting the superior dimensional accuracy and mechanical properties of the materials employed. Furthermore, it addresses the sustainability of the process by promoting material waste reduction during fabrication. These findings have significant implications for optimizing the production of occlusal devices in clinical settings.

Numerical analysis of unsteady free convection of Al2O3 inside a tubular reactor under the influences of exothermic reaction, and inclined MHD as an application to chemical reactor

This paper delves into the numerical investigation of aluminum oxide–water nanofluid thermal and dynamic performances under the influences of magnetic field application and chemical reaction, utilizing the Finite Element Method within a circular enclosure containing three inner tubes, as an application to the heat exchanging phenomenon between the reactive shell of the cavity and the surface of the triple tubes. Various governing parameters were studied for their interaction on the nanofluid flow and heat transmission rate within the proposed geometry, including the Rayleigh parameter (103≤Ra≤105), Hartmann parameter (0≤Ha≤61), nanoparticles concentration (0≤∅≤6×10-2), magnetic rotational angle (0o≤γ≤90o), and Frank-Kamenetskii parameter (0≤Fk≤3). The results indicated that raising Ra from 103 to 105 results in expediting the nanofluid velocity by 10.62 % and 100 % respectively as well as raising the total heat transfer efficiency. The nanofluid speed was also increased by 28.57 % when Fk has to further increase to a value of 3. When there was no exothermic activity present, the rate of heat transmission was at its lowest, and it was greater when the Fk value was 3. Similarly, there were discernible impacts in various areas of the geometry as the Ha number intensified and the Nuavg decreased. Improvements in local and mean Nusselt parameters are observed when the concentration of nanoparticles is increased, suggesting better heat transfer, achieving an increase by 7 % in the average Nusselt number. This research emphasizes the importance of nanoparticle concentration in raising the medium’s rates of heat transmission, contributing to advancements in energy storage development.

Experimental Investigation into Natural Convection Heat Transfer inside Triangular Enclosure with Internal Hot Cylinder

Natural convection air heat transfer and fluid movement currents around a hot circular cylinder inside an inclined triangular enclosure has been analyzed experimentally. Three different sizes of an enclosure with a long side of 20, 25, and 30 cm, the thickness of 1 mm, and depth of 50 cm were used in the present work to give three radius ratios. The effect of Rayleigh number, radius ratio, the rotation angle of triangle enclosure, and the inclination angle of the apparatus with horizontal axis ? on the heat transfer process was investigated. The ranges of these parameters were: Rayleigh number from 5×106 to 2.5×108, radius ratio (0.345, 0.455, and 0.618), rotation angle (0o, 45o, and 90o), and inclination angle (0o, 45o and 90o). The results show that the heat transfer rates increase with increase in Rayleigh number and as the rotation angle of enclosure is changed from 0o to 90o. Moreover, the heat transfer rate increases linearly with Rayleigh number at higher radius at rotation angle 0o, 90o only. While, it increases slightly with Rayleigh number at rotation angle 45o. Additionally, the higher heat transfer rates occur at vertical position of enclosure inclination angle 90o and rotation angle 0o (the base of triangle at the bottom) and it decreases as inclination angle deviates from 90o to 0o. This behavior is reverse completely at higher radius ratio 0.618. Empirical correlations for the average Nusselt number has been found to depend on Rayleigh number., radius ratio, rotation angle and inclination angle.

Heat transfer enhancement in a corrugated chamber filled with hybrid nanofluid under an influence of internal heated plate

PurposeThe purpose of this research is to scrutinize numerically the effect of internally equipped nonuniformly heated plate within wavy cavity on heat transfer enhancement in the case of hybrid nanofluid flow.Design/methodology/approachThe two-dimensional, steady, laminar, Newtonian and incompressible thermo-fluid flow phenomenon has been investigated numerically using Galerkin method. The considered parameters including number of waves (3–7), nondimensional length of heated plate (0.4–0.8), plate inclination angle (0º–90º), Rayleigh number (103–106) and concentration of nanoparticles (0.0–2.0) have been investigated in combination with involving hybrid nanofluid as a working fluid to augment thermal properties effectively. Two vertical wavy boundaries have low temperature whilst the other horizontal surfaces are adiabatic.FindingsThe Rayleigh number has a moderate impact on the values of Nusselt number, and skin friction parameter varied from 103 to 105 while it strongly affects them for Ra = 106, where Nu is roughly doubled (approximately 200%) in comparison with its value at Ra = 105 for all cases. Stream function is changed by the orientation of heated plate and Ra values, where its maximum value was 12.9 in horizontal position and 13.6 at vertical one. Results indicate a separation from the wavy walls at low Ra which tends to keep stagnation region at the deep parts of corrugated walls contrary the case at high Ra. The behavior of the isotherm contours tends to be distributed more evenly at lower values of Ra and angle of inclination lower than 45º. The resulting properties from mixing two materials for hybrid nanofluid into one base fluid show a good compromise between thermal capacity and heat conductivity, which is improved by 16% that leads to enhanced convective energy transport in the wavy chamber.Originality/valueThe originality of this work is the considered physical phenomenon where an influence of internal nonuniformly heated plate has been studied for the irregular geometry filled with a hybrid nanofluid. Such analysis allows defining the possible heat transfer enhancement for such an irregular cavity and inner heated plate.

Finite element and neural computations for energy system containing conductive solid body and bottom circular heaters utilizing Ag–MgO (50:50)/water hybrid nanofluid

This study investigates the natural convection of a hybrid nanofluid containing Ag–MgO (50:50) nanoparticles in water in a trapezoidal enclosure under the influence of Lorentz force. The cavity is heated from below by two semi-circular heaters containing a conductive solid body at the center. Galerkin finite element method is used to analyze the effects of various parameters such as Rayleigh number (103≤Ra≤106), conductivity ratio (10−2≤kr≤102), nanoparticle volume fraction (0≤ζ≤2%), Hartmann number (0≤Ha≤100), aligned magnetic field with angle (0o≤λ≤60o), side of solid central body (0.1L≤Ls≤0.4L) and diameter of circular heater (0.05L≤Dc≤0.4L) on heat transfer. The average Nusselt number decreases by 15%–20% with increasing cavity angle from 5 to 20 degrees (at Ra=5×104 and Ha=5), but adding just 1% of hybrid nanoparticles results in a 10% boost in heat transfer. Various training algorithms, including BFGS quasi-Newton, Resilient backpropagation, One step secant, Conjugate gradient, Bayesian regularization, and Levenberg Marquardt, are compared based on accuracy and computational time for input data generated from seven controlling parameters of heat transfer. Finally, the Levenberg Marquardt algorithm is used on two data sets for hot and cold walls with optimal neurons, and the genetic algorithm is used to predict the optimal values of the Nusselt number in a search space, which are verified with the particle swarm optimization algorithm. The minimum and maximum values for hot walls (Case I) were found to be 3.8005 and 17.5341, respectively, while for cold walls (Case II), the values were 0.9213 and 4.4434, respectively. These findings are significant for designing and optimizing cooling systems in various industries, including aerospace, automotive, and electronics.

A novel approach based on neural network to model the free convection within a differentially heated cavity partitioned by interior curved slats

A vertical closed cavity is presented by a modified configuration wherein, the cavity is partitioned by horizontal curved non-conductive slats. Then, the free convection flow of air in the modified differentially heated partitioned cavity is experimentally investigated as a function of governing variables. The cavity is bounded by two hot and cold isothermal parallel walls along with four non-conductive walls. The governing variables consist of the Grashof number (1 × 104≤Gr ≤ 2.05 × 104), slat's tilt angle (0o≤θ ≤ 180o), slat's curvature (0≤Cb ≤ 4 mm) as well as distance between the isothermal parallel walls (15.8 mm ≤ W ≤ 18.8 mm). After that, an optimal combination of the teaching–learning-based optimization (TLBO) and wingsuit flying search (WFS) algorithms is proposed as a new combinatorial optimization algorithm. The proposed combinatorial algorithm is tested over some standard benchmark functions and then integrated with the artificial neural network (ANN) to construct a novel hybrid model. In the following, the developed hybrid model is utilized for forecasting the average Nusselt number (Nuavg) of the cavity, as a function the governing variables. It was found that, the proposed combinatorial algorithm enhances the forecast effectiveness of the main ANN. Moreover, the creation of curvature on the slats, results in the suppression up to 34.35% in the heat transfer within the cavity.

Flexural Modulus Enhancement and Minimization of Printing Time and Part Weight for PET-G, Using Taguchi-GRA-TOPSIS Techniques

Fused deposition modeling (FDM) is becoming the most promised additive manufacturing (AM) process in recent years due to the evident benefits, such as high design flexibility, low cost, friendly and economically use. The current study considers an optimization of four different FDM parameters varied in three levels, as layer thickness (0.17 mm, 0.25 mm and 0.33 mm), infill density (25, 50 and 75%), shell thickness (0.8 mm, 1.2 mm and 1.6 mm) and raster angle (0o, 30o and 60o) with an objective to reduce printing time, part weight and to enhance flexural modulus using Polyethylene Terepthalate - glycol modified (PET-G) material. Mono optimization of FDM input parameters has been done using signal to noise ratio method obtained from Taguchi�s L9Orthogonal Array (OA) and multi response optimization is applied through Grey Relational Analysis (GRA) and technique of order preference similar to ideal solution (TOPSIS) techniques. The response or its criteria weightages are calculated using Shanon�s entropy and CRITIC method which gives different weightages for the considered responses. Printing time ranks top with 37% from entropy method followed by flexural modulus with 36% and part weight ranks last with 28%. Flexural modulus ranks tops with 43% followed by part weight with 29% and printing time takes last position with 28% weightage.The ranking of alternatives from GRA- entropy and GRA- CRITIC methods are similar by recommending A1B1C1D1 (0.17 mm layer thickness, 25% infill density, 0.8 mm shell thickness and 0� raster angle) but TOPSIS-entropy and TOPSIS - CRITIC methods suggested different parameter combination A2B3C1D2 (0.25 mm layer thickness,75% infill density, 0.8 mm shell thickness and 30� raster angle). From all the four different methods adopted for optimization, the parameter setting obtained from level total suggests A2B1C1D2 (0.25 mm layer thickness, 25% infill density, 0.8mm shell thickness and 30� raster angle) and completely opposite to the ranking of alternatives. The carried - out confirmation trials carried out validated the optimized settings resulted from different methods. Infill density is found to be the most significant factor as compared to other input factors over the output assessed parameters.

Analisis sudut panel solar cell terhadap daya output dan efisiensi yang dihasilkan

One of the natural potentials as a source of electrical energy is solar energy. The sun is the main energy source for most of the processes that occur on the surface of the earth. Solar radiation received by the earth's surface is a fundamental input for many aspects, mainly an important parameter in the application of solar cells as electricity generation. Sun cells are devices that can convert sunlight into electrical energy. In this study the data collection of solar cell panel data is collected which includes the solar radiation data, the voltage data generated and the electric current data generated at each variation of the tilt angle 0o, 8o, and 16o. This study aims to discover the effect of changes in the slope angle of solar cell panels on the efficiency of solar power generation systems. The study method used is an experimental development method which is carried out by using the tilt angle variation of the solar panel. The angle used by taking the tilt angle of the solar panel on the negative x-axis which aims to find the maximum tilt angle value. From the test results of 50 Watt Peak (WP) solar power plant installation, it can be concluded that the highest efficiency occurs at an angle of 16o and at 09:00 with a value of 46.076 %, then the second occurs at an angle of 8o and at 09:00 with a value of 45,052 %, then the lowest efficiency occurs at a slope angle of 0o and at 09:00 with a value of 43,986 %. Keywords: Angles, 50 WP panel, solar cell, power output, & efficiency.

Surface dose and acute skin reactions in external beam breast radiotherapy

The biologically relevant depth for acute skin reactions in radiotherapy is 70 µm. The dose at this depth is difficult to measure or calculate and can be quite different than the dose at a depth of as little as 1 mm. For breast radiotherapy with medial and lateral tangential beams, the skin dose depends on both the contribution from the entrance beam and the exit beam. The skin dose has been estimated in a breast model hemi-ellipse accounting for field size, beam energy, obliquity, lack of backscatter, fractionation, size and shape of the hemi-ellipse. The dose has been held constant along the axis of symmetry of the hemi-ellipse by introducing modulation as in clinical IMRT practice. Dose distributions have been computed as a function of the polar angle from the center of the hemi-ellipse. The exit dose always dominates the entrance dose for all realistic parameters. As a result, the surface dose is higher for 18 MV than 6 MV over the entire surface for all reasonable sizes and shapes of the hemi-ellipse. The results of these calculations suggest that substituting an 18 MV beam for a 6 MV beam to achieve greater skin sparing may have just the opposite effect. The ratio of the surface dose to the mid-depth dose ranges from about 35% at polar angle 0o to up to 70% at polar angle 80o. The dose rises sharply at angles above 30o. The surface dose rises moderately at all angles as the size of the hemi-ellipse increases. The effect of shape is somewhat complex: as the breast becomes flatter, doses at intermediate angles increase, but doses at small and large angles decrease. The biologically effective dose for erythema and moist desquamation is about 2 to 3 Gy higher at all polar angles for conventional fractionation (2.00 Gy × 25 fractions) than for hypofractionation (2.66 Gy × 16).

EXPERIMENTAL AND THEORETICAL STRESS ANALYSIS INVESTIGATION FOR COMPOSITE PLATE UNDER THERMAL LOAD

A paper focuses on the investigation ofthe stress-strain for E-glass fiber /polyester composite plates subjected to the uniform temperature at various factors, such as fiber volume fraction and fiber orientation. To study the stress analysis of composite plate two methods are used: The First method is an experimental test by applying a uniform temperature on the composite plate inside the furnace and a measure the deformation of the plate by using dial gage. The second method based on a finite element solution using ANSYS (ver. 15) program. The results presented here that, the maximum strain in longitudinal direction occurs at a ply angle (90º), whereas the minimum value at a ply angle (0º). However, the maximum strain in transverse direction occurs at a ply angle (0º) whereas the minimum value at a ply angle (90º). In general, the magnitude of thermal strain increases with increasing temperature difference (∆T) and decreases with increasing the fiber volume fraction ( Comparison the results of the experimental test with the numerical analysis of the thermal strain and evaluated the agreement between the two methods used, the maximum discrepancywas 19.7%.

NUMERICAL INVESTIGATION OF HEAT TRANSFER AND FLOW CHARACTERISTICS IN SHELL-AND U-TUBE HEAT EXCHANGER WITH BAFFLES

In this paper the numerical model of cylindrical coordinates, three dimensional of a laminar heat transfer and fluid flow inside shell and tube heat exchanger is examined. The thermo-hydraulic performance of heat exchangers is predicted with finite volume method by CFD simulations using ANSYS 15.0 code. Shell-and-tube heat exchanger is consisted of one pass of warm water laminar flow at the shell side and two passes single tube of laminar cold water. The annular baffles are inserted on shell side, and on the facing distances of the length of tube from the outer surface. Baffles are inserted with staggered position on the shell and tube to achieve good fluid circulation. Also baffles on the tube side are varied with angle inclination, number and diameter while only number and length on the shell side. The tube baffles angle inclination as (45o, 0o and -45 o) and without baffles and the range of Reynolds number from 100 to 2000. The results show high effect of baffles angles on the heat exchanger performance at high Reynolds number. Maximum heat transfer from hot fluid occurs at baffle with angle 0o and high 30mm. Also baffles number increases Nusselt number at high fluid flow rate while a little effect of baffle height and number on the fluid pressure drop is absorbed as obtained by Mica et.al [1].

LINEAMENT DENSITY INFORMATION EXTRACTION USING DEM SRTM DATA TO PREDICT THE MINERAL POTENTIAL ZONES

Utilization of remote sensing in geology is based on some identification of main parameters. They were the relief or morphology, flow patterns, and lineament. So it was necessary to study extraction method based on those parameters. This study aimed to obtain lineament density zone in the Geumpang area, Aceh, associated with mineral resource potential. Information of lineament density using remote sensing data was expected to help solve the problems that arised in the activities of early exploration, the difficulty of finding the prospect areas, so that the activities of pre-exploration always required a wide area and required a long time to determine the location of mineral prospect areas, it would have a direct impact on the financial of exploration activities. The used data was Landsat 8 and DEM SRTM of 30 m. The used method was processing of shaded relief on DEM data with the azimuth angle 0o, 45o, 90o, and 135o, then the result of hill shade process was done overlay, so DEM seen from all different azimuth angles. The results of the overlay were processed using the algorithm LINE with parameters such as the radius of the filter in pixels (RADI) 60, the threshold for edge gradient (GTHR) 120, the threshold for the curve length (LTHR) 100, the threshold for line fitting error (FTHR) 3, threshold for angular (ATHR) 30, and the threshold for linking distance (DTHR) 100. Vector lineament data from LINE algorithm process then performed density analysis to obtain lineament density zoning. Results from the study showed that the area has a high density lineament associated with mineral potency, so it was useful for exploration activities to minimize the survey area.

Analisis Variasi Penyudutan Arah Sinar Terhadap Informasi Anatomi Pedis Proyeksi Anteroposterior

Background : Many hospitals in the examination of pedis AP projection use 0º or perpendicular. It is not based on the theory. So that, it is done research about the variation of direction angle of AP projection in pedis examination toward anatomy information. The examination is aim to find how big the direction angle toward anatomy information which is result by examination pedis AP projection and angle which is result by optimal anatomy information.Methods : The research which is used descriptive quantitative research by experiment approach. The research is done by pedis phantom which eksposes four times with same expose factor with difference angle variation 0º, 5º, 10º and 15º cephalad and quenstionnaire filling. The research using the independent variable is the direction angle on the examination pedis AP projection and the dependent variable is anatomical information on the radiograph pedis AP projection. The quenstionnaire is filled by three respondents, they are Radiologist. The scoring result of the respondents processes and present in table and graphic to describe and analyse for getting conclusion.Results : From the scoring result, it is seen the influence of angle toward pedis anatomy information difference.When use of the angle 0º and 5º cephalad show very clear navicular. While the angle of 10º cephalad show open joint space between medial cuneiform and the intermediate cuneiform and a very clear cuboid. The angle of 15º cephalad shows a very clear tarsometatarsal joint. And then, the angle which is yield optimal anatomy information in examination pedis AP projection is the angle of 10 º cephalad.Conclusion : The radiographic technique of the AP projection pedis with a variation of 0º, 5º, 10º and 15º cephalad produces different anatomical information. At angle 0º and 5º showing very clear navicular, 10º cephalad revealed joints between the medial cuneiform and intermediate cuneiform and cuboid and 15º cephalad shows the tarsometatarsal joint very clearly. The optimal angle in generating anatomical information on the AP projection examination is 10 º cephalad.

Impact of LBP Topologies as Texture Descriptors on Ethnicity Identification

Many ethnicity identification techniques have been developed during the past years but the problem remains are the way of using these techniques, especially local binary pattern (LBP) method is one of these techniques which has shown its superiority in ethnicity identification. The original LBP operator mainly thresholds pixels in a specific predetermined window based on the gray value of the central pixel of that window. In this work, we comparativelystudy five different configuration neighborhood topology including circle, ellipse, parabola, hyperbola, and Archimedean topology. In the ellipse topology we used eight number of neighborhood pixels with different angle (0o, 45o, 90o, and135o), also in the circle topology we used vary the number of neighborhood pixels P: P = 8, P=10, and P = 12. K-nearest neighbor (KNN) has been used for identification task.A series of experimentations hasbeen performed on1200 face images were obtained from a collection of some standard databases. The topology computations that provide highly accurate identification consist of circle, and ellipse topology. In addition, the experimental results also indicate that a good accuracy and demonstrate by increasing the number of neighborhood pixel the result will be increase.

Design and Analysis Effect of Gantry Angle Photon Beam 4 MV on Dose Distributions using Monte Carlo Method EGSnrc Code System


 
 
 Varian linac modeling has been carried out to obtain Percentage Depth Dose (PDD) and profiles using variations gantry angle 0o, 15o, 30o , 45o in the vertical axis of the surface, field size 10x10 cm2, photon beam 4 MV and Monte Carlo simulations. Percentage Depth Dose and profile illustrates dose distributions in a phantom water measuring 40x40x40 cm3, changes gantry is one of the factors that determine the distribution of the dose to the patient research shows changes in Dmax in the Percentage Depth Dose is affected by changes in the angle gantry resulted in the addition of the area build up so it can be used for therapy in the region and produce skin sparing effects that can be used to protect the skin from exposure to radiation. The graph result is profiles obtained show lack simetrisan in areas positive quadrant has a distribution of fewer doses than the quadrant of negative as well as the slope of the surface so that it can be used for some cases treatments that require a depth and a certain slope, dose calculations are more accurate and can minimize side effects. 
 
 

Development of Fiberglass Woven Roving Composite as an Alternative Material for the Hull of Fishing Boat

This research has been carried out in order to analyse the possibility of fiberglass woven roving used as an alternative material for the hull of of fishing boat. The standard used in this analyzing process was the Standard of Biro Klasifikasi Indonesia (BKI), especially to find how the forces applied to the boat. Once the forces were found, they would be applied to justify the possibility mentioned above. The justification process was done by theoretically analyzing the mechanical properties of some fiberglass woven roving composites using mathematical software. The composites have been made by varying the mixture volume fraction between 0% - 100% within 10% interval, fiber orientation angle between 0o – 90o within 5o interval, and then the results which met the requirements according to BKI Standard would be justified by the results obtained from experimental analysis. Based on the experimental analysis results, it could be stated that the fiberglass woven roving with composition of 40% - 60% and fiber orientation angle 0o can be used as an alternative material for the hull of fishing boat.

Modelling and Analysis of the Dynamic Behavior of a Double Cylinder Inline 650cc Gasoline Engine with Crank Angle 0o for Rubber Mount

This paper presents a numerical study and analysis of the dynamic behavior of a double cylinder inline 650cc gasoline engine with crank angle 0o for rubber mount. Numerical study was done by mathematically modeling a double cylinder inline 650cc gasoline engine with crank angle 0o for rubber mount and simulating its dynamic behavior for 3 different connecting rod lengths:115.6mm, 125.6mm, and 135,6mm. Its mathematical model was developed from the physical model of engine produced by local manufacturer. All parameters used in the simulation are based on the engine specification provided by the manufacturer. In the mathematical model, connecting rod length was varied to investigate its influence to the engine’s dynamic behavior. Here, the engine system was modeled as a spring-mass-damper system excited by a periodic force produced by the cylinder working pressure with various excitation frequencies from 1000rpm to 5000rpm. The engine’s dynamic behavior was indicated by vertical motion (bouncing) and angular motion (pitching) of the engine mass, which is presented in displacement, velocity and acceleration. The results show that connecting rod length does not influence the engine’s dynamic behavior. Further, the increase in engine’s angular speed/excitation frequency influence significantly the engine’s dynamic behavior. The detail results of this study are reported and discussed in the paper.

DEFINITION FEATURES OF WORK ALUMINUM COVERINGS OF VERTICAL STEEL TANKS AT TILT

The floating coverings are used in vertical steel tanks to reduce the losses of the products stored there. Having better features the coverings of aluminum alloys have become wide-spread. Increasing the strength characteristics of the covering structure ensures the safe operation of vessels. The strength characteristics study involves the stress-strain state study of the coverings structures. In order to receive the characteristics of the impact of the stored product on the covering determining the load on the supporting structures of the floating cover, determine the critical provisions for the calculation of the strength, the mathematical model of the tank equipped by covering was made in the software package FlowVision. The of the floating covering in various operational positions was examined and the impact of the stored product on the covering design and the definition of the stress-strain, depending on the angle of slant were determined. The study was made in three stages. At the initial stage of the problem solving we constructed the three-dimensional model of the tank. For creating the geometry of the computational model of the tank the system of two-and three-dimensional computer-aided design and drafting AutoCAD was used, the geometric sizes were accepted on the basis of previously compiled baseline data for tank RVSP-5000. The floating covering and tank modeling was made separately to have an ability to vary the position of bodies relative to each other. At the next stage the incremental hydrogazodynamical calculation in FlowVision program was made. The final stage involves visualizing the results of hydrogazodynamical calculation processing, findings and conclusions. Based on the results of simulation and calculation the analysis of the operational positions of the covering at the rate of angle 0o, 1o, 5o, 10o. The results of calculation are shown visually as graphs of distribution parameters of pressure and speed module also we made the documentation values of investigated parameters in MS Excel format. The analysis of the results and studies of the floating cover in different positions revealed the of the covering influenced by the product stored. Hydrogazodynamical calculation results reflect the impact of the product stored on the tank floating cover during the exploitation. The research in PC FlowVision contributes not only to the study of the floating covering behavior in the tank , but also to model the stress state structures floating coverings, aluminum alloys, closest to the actual operating conditions.

Relação velocidade-acurácia em tarefa de contornar figuras geométricas e traçar linhas

Speed-accuracy trade-off was analyzed in two experiments, through Fitts´ law, in tasks simulated by computer. Experiment I analyzed the task of drawing geometric figures (triangle, square, and circle), in which it figure perimeter and line thickness were manipulated, providing index of difficulties (ID) between 1,25 and 2,15 bits. Experiment II analyzed the task of trace lines, in which it line size, line thickness, and line inclination angle (0º, 45º, 90º, 135º, and 180º) were manipulated, providing IDs between 3,5 and 7,5 bits. A linear regression analysis was used to evaluate the relationship between movement time (MT) and task’s ID. Determination coefficients higher than 0,9 (R² > 0,9) for the association TM x ID in experiments I and II were verified. Such results provided support for Fitts’ law on the performance of the computer simulated tasks of drawing geometric figures and trace lines.