Various Angles Of Inclination Research Articles

Investigation on the edge forces in ball end milling of inclined surfaces

This work focuses on the analysis of the edge forces generated in ball end milling of hardened alloy 55NiCrMoV6 steel. The investigated forces consider the effects of friction, rubbing and ploughing mechanisms between the work piece and tool flank face during machining process. The primary objective of the paper concentrates on the determination of edge forces in the range of variable surface inclination angles and increasing tool wear. The proposed approach involves the measurements of instant cutting forces in machine coordinates (Fz, Fy, Fz). Subsequently, the measured forces are converted to the forces in the tool coordinates (Ft_av, Fr_av, Fa_av). In the next step, the Ft_av, Fr_av, Fa_av forces are expressed in function of average uncut chip thickness. In order to obtain the edge forces values, the extrapolation of forces in the tool coordinates to the zero uncut chip thickness is made. The investigations reveal that edge forces are strongly affected by surface inclination angle and progressing tool wear. The growth of the tool wear induced the monotonic increase in edge forces values. Nevertheless, in case of surface inclination angles α≥15° the influence of this factor on edge forces was low. It was also shown that cutting force estimation with the consideration of the variable edge forces is characterized by a higher accuracy than one based on constant edge forces. Therefore, the proposed method can be employed in the reliable calibration of specific force coefficients contained in mechanistic cutting force models dedicated to the finish ball end milling of sculptured surfaces.

Effect of inclination angle on the performance of a shell and tube heat storage unit – An experimental study

This study includes experimental investigation on the performance of a shell and tube heat exchanger subjected to inclination angle variation. Paraffin RT35 is used as phase change material (PCM). The investigation was performed for modified Stefan numbers of 0.47, 0.53 and 0.59 and inclination angle rang from 0° to 90°. The Reynolds number is about 770 and the Grashof number is in the range of 4.6×104–5.8×104 which indicated that the flow is laminar. Results show that as the inlet temperature increases melting process accelerates and complete melting time reduces. Results also indicated that the rate of melting process in the first half of the process is more in the horizontal system with respect to the other inclinations. It is also revealed that the angle’s variation doesn’t affect the rate of heat transfer and the temperature during solidification which is due to the domination of conduction in this process. Results also clarified that during melting, the rate of heat transfer of the horizontal system is more than that of vertical, however the reverse is true for the solidification. It is also concluded that the average temperature of the horizontal heat exchanger sections closer to the inlet is more than the section nearer to outlet. However, when the 30°, 60° and 90° cases are considered, the PCM average temperatures of the sections nearer to the outlet are more.

Analysis of thermal management on processing of fluids within rhombic cavities: Heatlines vs. entropy generation

The present work involves the detailed heat flow visualization with the distribution of the entropy generation in order to estimate the energy efficiency of rhombic cavities with various angles of inclination (φ=45∘,60∘ and 75°) for different areas (A=0.5,1 and 1.5) with Ra=103−105 for Pr=0.015 and 1000. The cavities involve isothermally hot bottom wall in the presence of cold side and top walls. Results have been presented in the form of isotherms (θ), streamlines (ψ), heatlines (Π), entropy generation due to heat transfer (Sθ) and fluid friction (Sψ). Results have also been compared with the square cavity (φ=90∘) in terms of the total entropy generation (Stotal), average Bejan number (Beav) and average heat transfer rate (Nub¯ and Nul¯). The numerical studies clearly demonstrate that, the square enclosure may not be the optimal choice based on the lesser heat transfer rate and higher entropy generation. Overall, the rhombic cavities with φ=45∘ at A=0.5 may be concluded as the optimal design for the efficient thermal processing based on the higher heat transfer rate and lower entropy generation.

Scalable fabrication of microneedle arrays via spatially controlled UV exposure.

This paper describes a theoretical estimation of the geometry of negative epoxy-resist microneedles prepared via inclined/rotated ultraviolet (UV) lithography based on spatially controlled UV exposure doses. In comparison with other methods based on UV lithography, the present method can create microneedle structures with high scalability. When negative photoresist is exposed to inclined/rotated UV through circular mask patterns, a three-dimensional, needle-shaped distribution of the exposure dose forms in the irradiated region. Controlling the inclination angles and the exposure dose modifies the photo-polymerized portion of the photoresist, thus allowing the variation of the heights and contours of microneedles formed by using the same mask patterns. In an experimental study, the dimensions of the fabricated needles agreed well with the theoretical predictions for varying inclination angles and exposure doses. These results demonstrate that our theoretical approach can provide a simple route for fabricating microneedles with on-demand geometry. The fabricated microneedles can be used as solid microneedles or as a mold master for dissolving microneedles, thus simplifying the microneedle fabrication process. We envision that this method can improve fabrication accuracy and reduce fabrication cost and time, thereby facilitating the practical applications of microneedle-based drug delivery technology.

Braking index of isolated pulsars. II. A novel two-dipole model of pulsar magnetism

The magnetic dipole radiation (MDR) model is currently the best approach we have to explain pulsar radiation. However a most characteristic parameter of the observed radiation, the braking index n$_{\rm obs}$ shows deviations for all the eight best studied isolated pulsars, from the simple model prediction n$_{\rm dip}$ = 3. The index depends upon the rotational frequency and its first and second time derivatives, but also on the assumption of that the magnetic dipole moment and inclination angle, and the moment of inertia of the pulsar are constant in time. In a recent paper [Phys. Rev. D 91, 063007 (2015)] we showed conclusively that changes in the moment of inertia with frequency alone, cannot explain the observed braking indices. Possible observational evidence for the magnetic dipole moment migrating away from the rotational axis at a rate $\dot\alpha$ $\sim$ 0.6$^{\circ}$ per 100 years over the life time of the Crab pulsar has been recently suggested by Lyne et al. In this paper, we explore the MDR model with constant moment of inertia and magnetic dipole moment but variable inclination angle $\alpha$. We first discuss the effect of the variation of $\alpha$ on the observed braking indices and show they all can be understood. However, no explanation for the origin of the change in $\alpha$ is provided. After discussion of the possible source(s) of magnetism in pulsars we propose a simple mechanism for the change in $\alpha$ based on a toy model in which the magnetic structure in pulsars consists of two interacting dipoles. We show that such a system can explain the Crab observation and the measured braking indices.

Numerical optimization of tungsten monoblock tile in EAST divertor

The ITER-like tungsten divertor with toroidally symmetric 1mm×1mm chamfers on monoblock tiles has been installed in EAST in 2014. Hot spots were experimentally observed mostly along the toridial facing gaps between two columns of W/Cu monoblock units, which are often aggravated by installation misalignment. These hot spots can significantly degrade the power handling capability of W divertor and need to be alleviated.A numerical optimization model for tile chamfering design is built based on the finite element method (FEM), in which the numerical experiments are designed by the uniform table. The calculation results in ANSYS for these experiments are then processed employing the code Design and Analysis of Computer Experiments (DACE) in which the Kriging method is adopted to reconstruct a response surface. The optimum geometry can be derived from the minimum point on the surface. The results show that, under 200 MW/m2 parallel heat flux with an inclination angle of 3° with respect to tile surface, the maximum temperature on W tile with a 0.5mm misalignment can be decreased to 2084°C by adopting an optimized single-sided chamfer, 1.8 times lower than 1mm×1mm symmetrically chamfered tile. The optimum chamfering geometry has a strong dependence on the inclination angle of plasma flux to tile surface. As a result, the monoblock tiles in a flat cassette module need to be chamfered differently to adapt to the varied inclination angles.

Structural response of RC frame under seismic loading by varying inclination angle of cross bracing

Structural performance is greatly affected by the use of concrete bracing in high seismic zone areas. A study representing the structural performance of a five-storey RC braced frame structure, by varying the inclination angle of concrete bracing, has been carried out by the use of numerical modelling for an earthquake load relating to a PGA value of up to 0.24 g. To investigate the problem, hypothetical models have been generated and analysed in SAP 2000 software using 3D modelling. Three models with different angle of bracing (i.e., < 45 degree, 45 degree and > 45 degree) are studied and compared with frame structure. Design considerations as per 'UBC-97' and 'BCP-2007' were used and response spectrum analysis has been carried out to observe the structural behaviour under dynamic loading. The parameters considered in this study are lateral displacements, inter-storey drifts, time period, base shear forces and axial forces and bending moments in ground floor columns. It has been concluded that the bracing angle affects the overall performance of structure. RC braced frame model with bracing angle less than 45 degree gives better seismic performance in terms of lateral drift and forces in structural members.

Adaptive Slope Walking With a Robotic Transtibial Prosthesis Based on Volitional EMG Control

Allowing amputees to volitionally control robotic prostheses can improve the adaptability to terrain changes. In this paper, we propose a myoelectric controller for a robotic transtibial prosthesis to realize adaptive slope walking. It works together with the intrinsic controller, enabling amputee users to pay relatively less attention on myoelectric control during walking. Amputee users convey the information of ground slope to prostheses by consciously performing dorsiflexion and plantar flexion of the “phantom ankle” with different intensities at the beginning of the swing phase. Two channels of surface electromyographic signals are measured from the residual shank, and they are mapped to the inclination angle of the slope. Control parameters of the intrinsic controller are then calculated according to the estimated inclination angle. In this preliminary study, two transtibial amputee subjects were recruited. They were asked to convey six targeted inclination angles ( $\bf \pm 5^{\circ}$ , $\bf \pm 10^{\circ}$ , and $\bf \pm 15^{\circ}$ ) to the prosthesis with the trained myoelectric controller during level-ground walking, and satisfactory control performance was achieved. This experiment was designed to simulate the scenario of transiting from level-ground walking to slope walking. Experimental results of controlling the robotic prosthesis to walk on level ground and slopes further verified that it is promising for amputees to adaptively walk on the ground with varied inclination angles in daily life.

Turbulent convective heat transfer in an inclined tube filled with sodium

Turbulent free convection of liquid sodium in a straight thermally insulated tube with a length equal to 20 diameters and with end heat exchangers ensuring a fixed temperature drop is investigated experimentally. The experiments are performed for a fixed Rayleigh number Ra = 2.4 × 106 and various angles of inclination of the tube relative to the vertical. A strong dependence of the power transferred along the tube on the angle of inclination is revealed: the Nusselt number in the angular range under investigation changes by an order of magnitude with a maximum at the angle of 65° with the vertical. The characteristics of large-scale circulation and turbulent temperature pulsations show that convective heat transfer is mainly determined by the velocity of large-scale circulation of sodium. Turbulent pulsations are maximal for small angles of inclination (α = 20°–30°) and reduce the heat flux along the channel, although in the limit of small angles (vertical tube), there is no large-scale circulation, and the convective heat flux, which is an order of magnitude larger than the molecular heat flux, is ensured only by small scale (turbulent) flow.

An improved influence function method for predicting subsidence caused by longwall mining operations in inclined coal seams

Prediction of surface subsidence caused by longwall mining operation in inclined coal seams is often very challenging. The existing empirical prediction methods are inflexible for varying geological and mining conditions. An improved influence function method has been developed to take the advantage of its fundamentally sound nature and flexibility. In developing this method, the original Knothe function has been transformed to produce a continuous and asymmetrical subsidence influence function. The empirical equations for final subsidence parameters derived from collected longwall subsidence data have been incorporated into the mathematical models to improve the prediction accuracy. A number of demonstration cases for longwall mining operations in coal seams with varying inclination angles, depths and panel widths have been used to verify the applicability of the new subsidence prediction model.

Shear resistance of reinforced concrete beams in dependence on concrete strength in compressive struts

In the current European Code EN 1992-1-1 a truss model with variable inclination angle of concrete compressive struts with a quite wide range of inclination angle, from 21, 8 degrees to 45degrees, is intended for use for shear design of reinforced concrete beams. However, some researches and recommendations indicate special attention when choosing the lower bound of inclination angle of the concrete compressive struts, due to the reduced compressive strength of cracked concrete. This work reviews theoretical background and shear design methods of reinforced concrete beams. Relation of the shear resistance to crushing of the compressive struts as a function of their inclination angle has been investigated through a parametric study, where three different approaches have been used in order to limit stresses in the compressive struts. Based on the comparison of results from the analysis a recommendation for shear resistance calculation of reinforced concrete beams in dependence on concrete strength in compressive struts of the truss model is given.

The analysis of mixture kinematics in the mixer body frame with a screw elevator with variable generatrix

To improve the mixing intensity and vertical screw belt mortar mixer efficiency, it was proposed to use screw belts with generatrices that have a variable inclination angle to the screw axis, depending on the placement height. Studies of working processes for machines with a new mixer design have not been performed or are unknown. Therefore, a theoretical research and analysis of the mixture kinematics in the mixer body with new geometric parameters were conducted. The motion of elementary discrete mixture particle was considered as complex. It was divided into translational, together with a movable coordinate system, connected with the working body, and relative, by the screw belt surface. For given conditions, the motion patterns of the mixture particle were built. It has allowed to obtain the equations of motion coordinates of the particles, the equations for determining their relative and translational velocities, as well as for determining the direction of the velocity vectors. All types of accelerations that occur under these conditions were found. The equations for determining the magnitude and direction of the acceleration vectors of the relative and translational motions, as well as the Coriolis acceleration were obtained. The dependencies and motion patterns can be used for further research of new mixers with variable inclination angle of screw belt generatrices, as well as for calculating the forces of resistance to the working body motion and the mixer power consumption. The results may be useful in selecting a rational layout of the working bodies of mortar mixers in the space. This will allow to improve the quality of the design works.

Nonlinear Dynamic Characteristics of Variable Inclination Magnetically Coupled Piezoelectric Energy Harvesters

This paper investigates the nonlinear dynamic characteristics of a magnetically coupled piezoelectric energy harvester under low frequency excitation where the angle of the external magnetic field is adjustable. The nonlinear dynamic equation with the identified nonlinear magnetic force is derived to describe the electromechanical interaction of variable inclination angle harvesters. The effect of excitation amplitude and frequency on dynamic behavior is proposed by using the phase trajectory, power spectrum, and bifurcation diagram. The numerical analysis shows that a rotating magnetically coupled energy harvesting system exhibits rich nonlinear characteristics with the change of external magnet inclination angle. The nonlinear route to and from large amplitude high-energy motion can be clearly observed. It is demonstrated numerically and experimentally that lumped parameters equations with an identified polynomials for magnetic force could adequately describe the characteristics of nonlinear energy harvester. The rotating magnetically coupled energy harvester possesses the usable frequency bandwidth over a wide range of low frequency excitation by adjusting the angular orientation.

Interplay between order-parameter and system parameter dynamics: considerations on perceptual-cognitive-behavioral mode-mode transitions exhibiting positive and negative hysteresis and on response times.

A mathematical model is presented for the emergence of perceptual-cognitive-behavioral modes in psychophysical experiments in which participants are confronted with two alternatives. The model is based on the theory of self-organization and, in particular, the order parameter concept such that the emergence of a mode is conceptualized as an instability leading to the emergence of an appropriately defined order parameter. The order parameter model is merged with a second model that describes adaptation in terms of a system parameter dynamics. It is shown that the two-component model predicts hysteretic mode-mode transitions when control parameters are increased or decreased beyond critical values. The two-component model can account for both positive and negative hysteresis effects due to the interaction between order parameter and system parameter dynamics. Moreover, the model-based analysis reveals that response time curves look rather flat when response times are relatively decoupled from the mode-mode transition phenomenon. In general, response time curves exhibit a peaked close to the mode-mode transition point. In this context, the possibility is discussed that such peaked response time curves belong to the class of critical phenomena of self-organizing systems. In order to illustrate the relevance of peaked response time curves for future research and research reported in the past, results from a perceptual judgment experiment are reported, in which participants judged their ability to stand on a tilted slope for various angles of inclination. Response time curves were found that exhibited a peak around the mode-mode-transition points between "yes" and "no" responses.

Effects of wall waviness and temperature variations on the fluid flow and natural convection in an inclined corrugated channel

A parametric study involving the effects of some combinations of parameters, in particular, different combinations of the Rayleigh number, amplitude, temperature, and inclination angle of a two-dimensional long wavy-walled channel on a laminar incompressible fluid flow and natural convection within the channel is performed. The considered channel has an undulated wall as one side of the channel, and a parallel flat wall at a differentially different temperature as its counterpart. The channel sustains variable inclination angle, variable wavy wall amplitude, and variable temperature-difference between its two walls. A perturbation technique in terms of the small waviness of the undulated wall is performed to obtain a set of non-linear ordinary differential equations for the main flow and its perturbations. Solving this set of equations determines the streamline and temperature profiles for the imposed varying parameters. The results reveal that the fluid velocity along the channel axis increases with increasing the Rayleigh number, but decreases with increasing the channel inclination angle. The results also show that eddies appeared due to the steep undulations intensify as the temperature-difference between the two channel walls increases. The veracity of the present work is demonstrated through comparing the obtained results with those available in the literature.

Numerical Investigation of Laminar Natural Convection in Inclined Square Enclosure with the Influence of Discrete Heat Source

Natural convection heat transfer in a two-dimensional square enclosure at various angles of inclination is investigated numerically using a finite volume based computational procedure. The heat transfer is from a constant temperature heat source of finite length centred at one of the walls to the cold wall on the opposite side while the remaining walls are insulated. The effect of area ratio of the heat sourceAfrom 0.2 to 1.0, Rayleigh number Ra from 103to 107, and angle of inclination of the enclosureθvarying from 0° to 360° on the flow field and heat transfer characteristics are investigated. Streamline and isothermal line patterns are found to be similar at low Rayleigh numbers whereas at high Rayleigh numbers the differences are significant due to the influence of the parameters considered. Average Nusselt number decreases drastically as the position of the heat source is moved above the horizontal centre line of the enclosure. Correlation of the average Nusselt number which depends on the parameters of interest is obtained in the general formCRamAn. The correlation coefficients are determined by multiple regression analysis for the entire range of Rayleigh numbers analysed and the values found by correlation equations are in good agreement with the numerical results.

Effect of Fin and Insert on the Performance Characteristics of Open Loop Pulsating Heat Pipe (OLPHP)

The pulsating heat pipe, a serpentine tube of capillary dimension with many turns, has great impact on today's successful thermal management. It is an ascending technology to satisfy present requirement of increasing thermal performance. Focusing on this, an experiment has been done on the open loop pulsating heat pipes (OLPHP) to observe their performance characteristics by using two types of working fluid by varying inclination angles. The experiment is performed on 2.5mm inner diameter and 3mm outer diameter OLPHP with an insert of copper wire of 1mm diameter and fins are added on the condensation section. This investigation is done using methanol and ethanol with 50% filling ratio in OLPHP with 8 loops. In this experiment the effects on the performance of using fins with insert with two different fluids (methanol and ethanol) and the variation of inclination angles are investigated. The results show that the performance characteristics in all the circumstances are better for setup with fin and insert than the normal setup. As higher thermal resistance indicates better performance, so we can say that setup with methanol performs better than ethanol. This performance is best at 45˚ inclination angle. It can be seen that, higher the inclination angle, better the performance and this performance is best at 45˚ inclination angle for this experiment.

Effect of Fin and Insert on the Performance Characteristics of Close Loop Pulsating Heat Pipe (CLPHP)

The pulsating heat pipe, a serpentine tube of capillary dimension with many turns, has great impact on today's successful thermal management. It is an ascending technology to satisfy present requirement of increasing thermal performance. Focusing on this, an experiment has been done on the close loop pulsating heat pipes (CLPHP) to observe their performance characteristics by using two working fluids with varying inclination angles of 0̊ (vertical), 30̊ and 45̊. The experiment is performed on 2.5mm inner diameter and 3mm outer diameter CLPHP with an insert of copper wire of 1mm diameter and fins are added on the condensation section where the evaporation section is 50mm, adiabatic section is 120mm and condensation section is 80mm. This investigation is done using ethanol and methanol with 50% filling ratio in CLPHP with 8 loops. Methanol shows better performance at 45̊inclination than ethanol due to their physiochemical properties at different conditions. In this experiment the effects on the performance of using fins with insert and the variation of inclination angles are investigated. The results show the better performance characteristics and enhancement of heat transfer in the present experimental set-up because of using fin and insert.

Swift perspective shape matching algorithm based on Phong’s model for FPC stiffener bonding systems

Purpose – This paper aims to solve the issue of target positioning in auto stiffener bonder (ASB) systems for flexible printed circuits. Design/methodology/approach – The proposed approach uses Phong’s bidirectional reflectance distribution function (BRDF) model to simulate the reflection of light off a target in ASB systems to predict the current pose of the target based on image brightness, update the template, decrease the initial errors in the template and narrow down the search range. Findings – The experimental results indicate that the proposed approach can predict the inclination angle of the target with precision, presenting angle prediction errors of less than three degrees. Furthermore, with larger inclined angles, the overall matching errors were less than 1.5 pixels. Comparisons with the unmodified matching algorithm revealed that the proposed approach resulted in 65 per cent less calculation time for the algorithm and 14 per cent higher overall work efficiency in the ASB system. Originality/value – The edge-based perspective shape matching algorithm was modified using the Phong BRDF model and enhanced algorithm efficiency with the target pose prediction method while ensuring the precision and robustness of the system. The proposed approach has high potential value and can be expanded to recognition systems for objects with varying inclination angles and highly reflective surfaces.

Investigations on Direct Shear Tests and PFC&lt;sup&gt;2D&lt;/sup&gt; Numerical Simulations of Rock-Like Materials with a Hole and Prefabricated Cracks

Direct shear tests conducted on the samples containing a central hole and prefabricated cracks are performed to make an analysis on the effects of the inclination angle, the number of prefabricated cracks and the normal stress on shearing characteristics. And the particle flow code in two dimensions (PFC2D) based on discrete element is applied to carry on simulations on this tests. The micro mechanical parameters of the simulation models are determined by the calibration processes conducted on the shear stress-stain numerical curves of intact samples and the samples containing a pre-existing hole in both experimental tests and simulation tests. And then the micro mechanical parameters obtained above are applied in the simulation models containing prefabricated cracks with varying inclination angles and numbers. Based on the comparisons conducted on simulation curves and experimental curves, investigations of the initiation, propagation and coalescence mechanisms of the prefabricated cracks in both macro and micro scales are performed. And the results may shed lights on the failure mechanism of the surrounding rock involving holes and cracks.