Equal Angles Research Articles

Sensitivity analysis of the equal angle divider mechanism kinematics with the synthesis of the joint gap tolerances

ABSTRACTTolerance analysis of mechanical components and assemblies is a key element in the industry for improving product quality and reducing overall cost. This paper is an attempt to propose a methodology to formulate and compute the kinematic assembly variations with respect to the critical dimensions (joint clearances) by calculating the homogeneous matrix of loops with considering the transforming and rotation matrix, the tolerance sensitivities, the geometrical responses to assembly variations, and the tolerance sensitivity of mechanism for clearance in the joints in different motion phases. The analysis is performed by the systematic methodology which is extended for kinematic sensitivity and positional error analysis with published results.

Experimental Study of Eccentrically Loaded Single Angle Compression Member

An experimental investigation of the buckling response of single angle compression member is presented here. Equal angle was used with a range of maximum principal slenderness ratios to determine elastic and inelastic failure characteristics, including flexural torsional effects. A nonlinear finite element model applicable to steel single angle compression members eccentrically loaded through one leg has been developed using an existing finite element package. A finite element study was conducted to investigate the strength and behavior of angle compression member. The finite element analysis was performed for angle as per experimental investigation. The results obtained by this study, emphasize the importance of the flexural–torsional buckling mode, especially in the inelastic range of behavior for angle.

Mapping geometry in Fizeau transmission spheres with a small f-number.

The ideal mapping geometry in a Fizeau interferometer is to map equal height increments on a flat object and equal angle increments on a spherical surface to equal heights on the detector. So the initial intent of the optical design of Fizeau transmission spheres (TSs) is to provide R-θ mapping geometry for equal angle increments. The corresponding unequal heights mapping will introduce retrace error as coma when linear carrier fringes exist. On the contrary, equal heights mapping with R-sin θ mapping geometry will avoid linear carrier fringes induced coma error. These two different mapping geometries conflict especially for the TS with a small f-number. In this paper, we will first explore the design and the performance of the f/0.75 TS according to the two different mapping geometries, and then evaluate the mapping geometry for the commercial ZYGO f/0.75 TS, and give some engineering notes for the designers, the metrologists, and the fabricators in the optical laboratory.

Study of the Enhancement of the Efficiency of the Monocrystalline Silicon Solar Cell by Optimizing Effective Parameters Using PC1D Simulation

In this paper, simulation of a monocrystalline silicon solar cell was done using PC1D software. The impact of different solar cell parameters, with their effects on power and efficiency, has been investigated. For a p-type monocrystalline silicon wafer, with an area of $10\times 10$ cm2 and a thickness of 300 μm, initial simulation shows a 12.10% efficient solar cell. To optimize the simulation experimentally obtained data has been used in the texturization process. It is seen that the textured surface reduces reflection and increases the efficiency of the solar cell at least 1–2%. From the simulation it is seen that the optimum value of p-type doping concentration is $1\times 10^{17}$ cm− 3 and n-type doping concentration is $1\times 10^{18}$ cm− 3. 200.3 μm diffusion length is considered as optimum. Both sides textured wafer with pyramid height of 2–3 $\mu \mathrm {m}$ and equal angles of 54.74 degrees produces the best result in simulation. An anti-reflection coating with 2.019 refractive index and a thickness of 74 nm is considered as optimum. By optimizing the effective parameters, a 20.35% efficient solar cell has been achieved by simulation.

Application of computer processing of experimental data from analysis of chip formation zone on photoelastic models

In the experiments carried out using photomechanical method, only the isochrome pattern is directly recorded on photoelastic models and the isoclines (lines of equal angles of inclination of the principal stresses) must be traced manually for each of the fixed values of the polarization planes. Further processing is also performed manually, isostatic lines (trajectories of principal stresses) are constructed from the isocline pattern, and the field of the slip lines, or maximum tangential stresses, is constructed from the obtained isostatic field. Such multi-step path (isoclines-isostatic lines-slip lines) containing manual processing at each stage leads to accumulation of errors. The research presented in the article largely removes these problems. In order to actualize a load similar to the one acting on the wedge front surface, a large-scale photoelastic model and a special experimental stand were developed. The scale of the model (10:1) was chosen as great as practicable from the condition of its placement in the optical field of the PPU-7 (plane polarization unit). The scheme of chip formation, the shape of the photoelastic model and its loading is given. The scheme of the stand for loading the chip formation zone of the model under study is described. The task of reducing labor intensity of the experimental part and increasing the accuracy of the obtained results was solved by using a digital camera and a specially developed technology for computer processing of photograms. Pressure diagram describes the nature of loading models in experiments. The results of the experiments were presented in the form of a series of digital photographs subjected to further computer processing, the purpose of which was to obtain isocline mesh, construct isostatic lines field, and then fields of slip lines. Analysis of the application of digital recording and computer processing of photograms significantly reduce time of performing the experimental part by abandoning the traditional method of drawing isoclines on tracing paper. In addition, the accuracy of the fields of the isostatic and slip lines increases because in the initial for their construction isocline field errors that are unavoidable with manual fixation are eliminated.

Experimental and Numerical Study on Single-Bolted Cold-Formed Angles under Tension and Compression

Angle sections are commonly designed to bear only axial force, usually neglecting the additional bending moments resulting from the eccentric connection and the shift of the effective centroid. The current work deals with the capacity of single-bolted equal angle sections made from cold-formed steel. The experimental investigation presented herein includes tension and compression tests which subsequently are compared with the corresponding code provisions. Numerical analyses are also presented based on a detailed finite element simulation. Finally, a reliability analysis is implemented in order to demonstrate the reliability of the design rules for cold-formed steel angle columns. Results indicate a small discrepancy on the strength prediction in general by EN 1993-1-3, as well as by the AISI for slender columns and a more conservative one by EN 1993-1-1. A comparison of the above results is clearly illustrated herein in graphical forms.

Continuous Inclination Measurements and BHA Modeling Help Detect Microdoglegs

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 184074, “Microdogleg Detection With Continuous Inclination Measurements and Advanced BHA Modeling,” by K.A. Mills, SPE, and S. Menand, SPE, DrillScan, and R. Suarez, SPE, Nabors, prepared for the 2016 SPE Eastern Regional Meeting, Canton, Ohio, USA, 13–15 September. The paper has not been peer reviewed. Microdoglegs are a natural effect of any vertical or directional well that can explain a wide variety of downhole problems. A trajectory-prediction model able to calculate the inclination and azimuth approximately every 12 in. has been developed to estimate microdoglegs using standard surveys, bottomhole-assembly (BHA) data, and steering parameters. This new methodology combining downhole data measurements with drillstring-modeling analysis highlights the potential for drilling optimization and wellbore placement. Wellbore Trajectory Standard Surveys. Surveys are generally taken at an interval of every 95 ft, the length of one stand. While the general recommendation is to decrease the survey interval when building faster than 3°/100 ft, this is often neglected because there is no advantage seen in wellbore-positioning-uncertainty models. The well path between each survey point typically is calculated using the minimum-curvature approach, which assumes a curve of equal angle along the surface of a sphere with only one radius in a 3D plane. Looking at the well as a whole, this approach appears logical and yields reasonable-looking trajectories; however, when examining more-frequent survey data, it becomes obvious how this method can mislead users to think that the well path is much smoother than it actually is. Continuous-survey measurements have enabled the industry to take a closer look at what is happening between survey points, in highlighting microdoglegs quite often undetected by standard surveys. Continuous Surveys. Doglegs are generally discussed on a well level. Wells are analyzed for tortuosity looking at the change in trajectory from one survey point to the next. Little thought is given to what changes happen between those points unless a dysfunction occurs. Aggressive directional work can lead to the creation of microdoglegs, or doglegs on a scale of a few feet. Quick changes in direction create microdoglegs, which can contribute overall to higher torque and drag. In examining continuous surveys, the actions of the directional driller can be seen clearly and doglegs can be examined more closely. While continuous-survey data have become more common in the industry, not all measurement-while-drilling (MWD) tools are equipped for the measurements and, generally, data must be processed at surface on the basis of the previous survey. In the absence of continuous-survey data, BHA modeling run on a step-by-step basis can aid in wellbore placement, failure analysis, and post-well evaluation.

Study of Equal Angle Subjected to Compression for Bolted end Connection

The work presents the results of an experimental and analytical investigation of the buckling response of single angle and double angle closely spaced back to back for bolted connection. Equal angle was used with a range of maximum principal slenderness ratios to determine elastic and inelastic failure characteristics, including flexural torsional effects. A nonlinear finite element model applicable to steel single angle compression members eccentrically loaded through one leg has been developed using an existing finite element package. A finite element study was conducted to investigate the strength and behaviour of angle compression member. The finite element analysis was performed for angle as per experimental investigation. The results obtained by this study, emphasize the importance of the flexural–torsional buckling mode, especially in the inelastic range of behaviour for angle.

Effect of Extrusion-Sheer on the Microstructure and Mechanical Properties of Magnesium Alloy AZ31

The effect of extrusion combined with shear (ES) on the microstructure and mechanical properties of magnesium alloy AZ31 is studied. The additional die providing shear deformation of the extruded bars (two successive turns of the calibrating channel to equal opposite angles) provides refinement of grains. Growth of the deformation temperature causes grain growth. The intensity of the x-ray reflection from basal plane (0002) after the ES increases. After the deformation at 420°C fracture mainly develops by the transgrain mechanism. After the deformation at 450°C the maximum hardness corresponds to the largest grain size in the central part of the bar, and the fracture is chiefly determined by twinning.

Experimental Study on Torsional Vibration of Transmission System Under Engine Excitation

Aiming to the problem of torsional vibration of the automobile transmission system caused by engine excitation, the experiment with dual mass flywheel small SUV cars as example, conducting torsional vibration test. The torsional vibration signal is tested by the equal angle sampling technique and the order analysis method. The torsional vibration data of the constant speed working condition obtained are dealt with and analyzed by MATLAB, and the order signal of the engine excitation is obtained. The influence of the engine excitation response on the torsional vibration of the transmission system and the torsional vibration reduction effect of the dual mass flywheel is verified, which serves as a basis and reference for torsional vibration analysis and the design and improvement of dual mass flywheel.

End Restraints in Steel Angles in Lattice Towers

Introduction: Test data on single angle compression members with various end connection arrangements is used to develop adjustment factors for effective buckling lengths. A connection length parameter is proposed and evaluated based on test data. Results from a total of 31 equal leg test angles with single-, double- bolts and fixed ends are used. Methods: Slenderness ratios considered ranged from 150 to 312. Angle sizes ranged from 38 x 38 x 3.2 (mm) to 89 x 89 x 6.4 (mm). Estimated connection lengths were about 12.5% of the member length for single-bolt joints; 24.7% for double-bolt joints and 45.6% for fixed joints. Computed effective length factors ranged from 0.544 to 0.875. Results: Results seem to indicate that it is possible to define and calculate connection length of a lattice tower angle member. Suggestions for incorporating connection length issues in routine designs are made.

Instability wave-streak interactions in a supersonic boundary layer.

Optimal initial conditions for transient growth in a two-dimensional boundary layer flow correspond to stationary, counter-rotating vortices that subsequently develop into streamwise elongated streaks, which are characterized by an alternating pattern of low and high streamwise velocity. For incompressible flows, previous studies have shown that boundary layer modulation due to streaks below a threshold amplitude level can stabilize the Tollmien-Schlichting instability waves, resulting in a delay in the onset of laminar-turbulent transition. In the supersonic regime, the linearly, most-amplified waves become three-dimensional, corresponding to oblique, first-mode waves. This change in the character of dominant instabilities leads to an important change in the transition process, which is now dominated by oblique breakdown via nonlinear interactions between pairs of first-mode waves that propagate at equal but opposite angles with respect to the free stream. Because the oblique breakdown process is characterized by a rapid amplification of stationary streamwise streaks, artificial excitation of such streaks may be expected to promote transition in a supersonic boundary layer. Indeed, suppression of those streaks has been shown to delay the onset of transition in prior literature. Consistent with those findings, the present study shows that optimally growing stationary streaks indeed destabilize the first-mode waves, but only when the spanwise wavelength of the instability waves is equal to or smaller than twice the streak spacing. Transition in a benign disturbance environment typically involves first-mode waves with significantly longer spanwise wavelengths, and hence, these waves are stabilized by the optimal growth streaks. Thus, as long as the amplification factors for the destabilized, short wavelength instability waves remain below the threshold level for transition, a significant net stabilization is achieved, yielding a transition delay that is comparable to the length of the laminar region in the uncontrolled case.

18.04: Experimental investigations of members from angle sections

ABSTRACTAngle sections are commonly used in many Civil Engineering applications and especially in lattice towers for telecommunication purposes. Nevertheless, due to their geometrical characteristics, design expressions, as for example those included in EN1993‐1‐1 or EN 1993‐3‐1, do not apply for cross sections or members composed of angle sections. Although a number of numerical investigations for cross section strength and member stability and proposals for relevant design expressions exist, only limited experimental investigations on members from angle sections, mostly on cold‐formed ones, can be found in literature.In the current paper a test campaign on members from equal leg hot rolled angle sections that has been carried out at the Institute of Steel Structures of the National Technical University of Athens (NTUA) is presented. Tests included eight 3‐point bending tests and thirty‐one buckling tests on columns subjected to concentric and eccentric compression. The aim of the research is to use the experimental data for calibration of numerical models, the investigation of possible inelastic reserves for angles that were detected in analytical models and as reference for the development of new design expressions oriented towards angle sections only.

Grey target decision-making model of interval grey number based on cone volume

PurposeThe purpose of this paper is to propose a grey target decision model based on cobweb area in order to overcome the effect and influence from the extreme value of the index on the decision result. However, it does not take into account the impact of the correlation between indicators on the angle of the index, and produce a certain degree decision information distortion as a result of the equal angle between the indicators. In order to solve the above problems, a novel grey decision-making model based on cone volume is proposed.Design/methodology/approachIn this paper, the model uses the whitening weight function to whiten the interval grey number, and the Delphi method and the maximal entropy method are exploited to integrate the weight of the index. On the basis of this, the center of the bull’s eye, the weight and the index value are constructed as the center circle, the radius, and the high cone, respectively. The scheme is selected by the volume of the cone, the decision is made according to the order relation, and the example is utilized to prove and analyze the validity of the proposed model.FindingsThe results show that the proposed model can well improve the traditional grey target decision-making model from the modeling object and modeling method.Practical implicationsThe method exposed in the paper can be used to deal with the grey target decision-making problems which characteristics are multi-indexes, and the attribute values are interval grey numbers.Originality/valueThe paper succeeds in overcoming the disadvantages of grey target decision making based on the target center distance and the cobweb area.

Geometrically Thick Obscuration by Radiation-driven Outflow from Magnetized Tori of Active Galactic Nuclei

Abstract Near-Eddington radiation from active galactic nuclei (AGNs) has significant dynamical influence on the surrounding dusty gas, plausibly furnishing AGNs with geometrically thick obscuration. We investigate this paradigm with radiative magnetohydrodynamics simulations. The simulations solve the magnetohydrodynamics equations simultaneously with the infrared (IR) and ultraviolet (UV) radiative transfer (RT) equations; no approximate closure is used for RT. We find that our torus, when given a suitable sub-Keplerian angular momentum profile, spontaneously evolves toward a state in which its opening angle, density distribution, and flow pattern change only slowly. This “steady” state lasts for as long as there is gas resupply toward the inner edge. The torus is best described as a midplane inflow and a high-latitude outflow. The outflow is launched from the torus inner edge by UV radiation and expands in solid angle as it ascends; IR radiation continues to drive the wide-angle outflow outside the central hole. The dusty outflow obscures the central source in soft X-rays, the IR, and the UV over three-quarters of solid angle, and each decade in column density covers roughly equal solid angle around the central source; these obscuration properties are similar to what observations imply.

Beyond-Cassie Mode of Wetting and Local Contact Angles of Droplets on Checkboard-Patterned Surfaces.

Droplet wetting and distortion on flat surfaces with heterogeneous wettability are studied using the 3D Shan-Chen pseudopotential multiphase lattice Boltzmann model (LBM). The contact angles are compared with the Cassie mode, which predicts an apparent contact angle for flat surfaces with different wetting properties, where the droplet size is large compared to the size of the heterogeneity. In this study, the surface studied consists in a regular checkboard pattern with two different Young's contact angles (hydrophilic and hydrophobic) and equal surface fraction. The droplet size and patch size of the checkboard are varied beyond the limit where Cassie's equation is valid. A critical ratio of patch size to droplet radius is found below which the apparent contact angle follows the Cassie mode. Above the critical value, the droplet shape changes from a spherical cap to a more distorted form, and no single contact angle can be determined. The local contact angles are found to vary along the contact line between minimum and maximum values. The droplet is found to wet preferentially the hydrophilic region, and the wetted area fraction of the hydrophilic region increases quasi-linearly with the ratio between patch and droplet sizes. We propose a new equation beyond the critical ratio, defining an equivalent contact angle, where the wetted area fractions are used as weighting coefficients for the maximum and minimum local contact angles. This equivalent contact angle is found to equal Cassie's contact angle.

Analysis of an Integrated 8-Channel Tx/Rx Body Array for Use as a Body Coil in 7-Tesla MRI

Object In this work an 8-channel array integrated into the gap between the gradient coil and bore liner of a 7-Tesla whole-body magnet is presented that would allow a workflow closer to that of systems at lower magnetic fields that have a built-in body coil; this integrated coil is compared to a local 8-channel array built from identical elements placed directly on the patient. Materials and Methods SAR efficiency and the homogeneity of the right-rotating B1 field component (B_1^+) are investigated numerically and compared to the local array. Power efficiency measurements are performed in the MRI System. First in vivo gradient echo images are acquired with the integrated array. Results While the remote array shows a slightly better performance in terms of B_1^+ homogeneity, the power efficiency and the SAR efficiency are inferior to those of the local array: the transmit voltage has to be increased by a factor of 3.15 to achieve equal flip angles in a central axial slice. The g-factor calculations show a better parallel imaging g-factor for the local array. The field of view of the integrated array is larger than that of the local array. First in vivo images with the integrated array look subjectively promising. Conclusion Although some RF performance parameters of the integrated array are inferior to a tight-fitting local array, these disadvantages might be compensated by the use of amplifiers with higher power and the use of local receive arrays. In addition, the distant placement provides the potential to include more elements in the array design.

Optimal design of a concave annular high intensity focused ultrasound transducer for medical treatment

In this study, a concave annular array transducer was designed to generate high intensity focused ultrasound for medical therapeutic applications. First, a detailed theoretical equation was derived to determine the sound pressure distribution from the transducer. To facilitate the design, each annulus in the array was simulated by multiple piston sources. Use of the piston sources can generalize the acoustic field analysis of the concave annular transducer and thus it is applicable to any other types of ultrasound transducers. The validity of the equation was verified by comparing the results calculated by the equation with those calculated from finite element analysis. Using this equation, we developed a new design scheme to optimize the structure of the annular transducer, using OptQuest-Nonlinear Programming algorithm, to meet the constraints that the main lobe should exist at a specific region on the normal axis of the transducer and the level of the maximum sidelobe, including the grating lobe, should be lower than the main lobe by −12.0dB that is a very strict criterion when compared with that in precedent works. For the annular structure, two different schemes were investigated: (1) an equal area channel structure obtained by setting the area of all the channels equal and (2) an equal angle channel structure obtained by setting the angular width of all the channels equal. The optimized structures of both configurations satisfied all the performance constraints for the sidelobe level as well as the geometric and dynamic focusing. The new design method developed in this work can facilitate the analysis and efficient development of HIFU transducers for medical treatment.

Experimental analysis of large-scale pullout tests conducted on polyester anchored geogrid reinforcement systems

The pullout resistance of reinforcement, such as geogrids in mechanically stabilized earth (MSE) walls, includes the skin friction between the soil and solid geogrid surfaces. It also includes the bearing resistance against the transverse ribs, which has a greater influence on the production of pullout resistance. Taking the current limitations involved in producing woven polyester geogrids into consideration (i.e., the limited thickness of the transverse ribs), the amount of bearing resistance developed in front of transverse ribs is limited in the pullout mechanism. Thus, along with introducing an innovative and applied system, this research has endeavoured to demonstrate the effective performance of this new system in increasing the passive resistance — and thereby the pullout resistance — of standard geogrids. This new system, which is formed by adding steel transverse elements (a set of steel equal angles) to the ordinary polyester geogrids by means of nuts and bolts, is called an anchored geogrid (AG). The experimental results show that a spacing-to-height ratio of transversal elements equal to 5 gives the maximum pullout resistance for a polyester AG system in sandy soil used in the study. With an optimum arrangement, this system is capable of increasing the pullout resistance of the ordinary geogrid system by 65%. In addition, based on the plasticity solution, the pullout bearing failure mechanisms of a single isolated transverse element in the polyester AG system depend on overburden pressures.

Выявление аномальных опознаков при геодезическом ориентировании фототриангуляции

When building phototriangulation ways to identify landmarks with gross blu nders in planning coordinates or their identification. They are based on an assessment of the condition of the equality the scale of line segments connecting the landmarks. However, in this case, there is the possibility of detecting a blunder in the situation of landmarks only in the direction of the segment. The article considers a method of detecting a blunder in the situation of landmarks also in the perpendicular direction to the cut. This assessed the condition of equal angles between identical segments. It is shown that as the scale and angles are invariants of orthogonal transformations, it is advisable to apply them as criteria to stage the planned reduction of phototriangulation. In the process of analysis of the quality of landmarks reveals the real level of error plane coordinate landmarks. This treatment begins with a task notoriously tough admission, which excludes high-quality landmarks. Then follows a gradual increase in the tolerance. As a criterion for task completion is assumed that the correct project build the mapping component of the anomalous landmarks should not exceed a certain level in the order of 10 - 15 percent. An example of the practical application of the method when building a phototriangulation for the images of TK-350, scale 1