Face Angle Research Articles

Morphology and Optical Properties of Precipitated Vivianite, Fe3(PO4)2·8H2O

AbstractCrystals of vivianite, Fe3(PO4)2∙8H2O, belonging to the monoclinic prismatic class 2/m, are grown by precipitation from aqueous solution at temperatures from 25 to 56 °C. At 25 °C aggregates are dominating, but at 35 °C and above single crystals are more common, being tabular along {010} and most often with parallelogram outline; in a few cases twins are observed. The outline is distinct and consistent with published lattice parameters, but at low temperature the {010} faces are very rough as judged from interference colors seen in the polarizing microscope. Lateral faces belonging to the {110} form are visible on crystals grown at 45 and 56 °C, and the widths of their projections on {010} as measured with a micrometer eyepiece served for estimating crystal thickness, making use of the face angle from lattice parameters. Optical parameters are determined by a combination of three methods: 1) measurement of birefringence with an Ehringhaus 6λ compensator, 2) Kamb's method for the optic axis angle determined by the angle‐of‐flight method in conoscopic illumination, and 3) visual interferometry using a polarizing microscope incorporating a Mach–Zehnder interference device. Reasonably precise values of principal refractive indices in the expected range are found.

Effect of the aging process on columella-labial, naso-mental and facial angles and how to apply it in clinical practice.

Aging is the result of the interplay of changes occurring in the facial skeleton, ligaments, muscles, adipose tissue, and skin (1), and these changes befall each mentioned structure at a different pace, start in each individual at a different age, and differ between ethnic background. (4) It changes directly the measurements of the face angles, making the face more concave and flattened aspect, while the young face presents a more convex and rounded aspect. Female skulls had an increase in all transverse facial widths and depth of the middle face with increasing age. Therefore, aging is consequence of progressive changes through intrinsic and extrinsic factors (5) and different methods can be used to assess and diagnose these changes. The aim of the study is to evaluate facial angles and their aging changes. A retrospective study was performed with a total of 1213 Caucasian female patients in the author's private clinic. The angles evaluate age-related changes were analyzed: facial, naso-mental, and columella-labial angle. Photograph analysis program Vectra 3D (Canfield) was used to perform the anthropometric assessment of the angles, and after data collection, the analysis was performed statistics. We could conclude angles analyzed change with age, while two angles increase (naso-mental and facial angle), the other decreases (columella-labial angle). The study reinforces the principle of an objective clinical anthropometric assessment of facial angles as a relevant guide for a more appropriate treatment plan for the doctor to perform aesthetic procedures in order to restore a youthful face.

MONTHLY DESIGN DATA FOR MAXIMUM SOLAR RADIATION FALLING ON COLLECTOR ARRAYS IN BAGHDAD CITY

Increasing use of solar energy as a clean and free solution for energy demand necessitates proper use of its equipment, enhanced spatial planning and distribution of solar collectors, optimum directional facing and tilt angle to ensure maximum solar radiation falling, and decreasing as possible as the shading effects of panel arrays. Most existing references lack comprehensive data about shading effects that varied along the year and design of solar array. In the present work, enhanced theoretical design data of solar collector arrays were tabulated for each month in Baghdad. MATLAB program was used to calculate the maximum clear sky solar radiation per unit area per day. The tabulated data yields an economically saved design of solar field or rooftop collector systems. The results indicated that, the shading effect on panel arrays almost vanishes when the distance between two panel rows to panel height ratio is greater than 1 in summer and greater than 2 in winter.

Analysis of the main factors affecting bottom hole assembly Re-entry into main hole in forward drilling of fishbone wells

Wellbore re-entry is one of the critical technologies in fishbone well drilling. In the sequence of forward drilling, the main hole is designed as a low wellbore and the branched hole is designed as a high wellbore to ensure that the bottom hole assembly (BHA) can re-enter the main wellbore. However, there is no quantitative theoretical analysis regarding the reliability of wellbore re-entry at present. In order to analyze the reliability of the main hole re-entry, an analysis method was provided in this paper. Firstly, a detailed description of the wellbore model around the sidetracking point was built, which can consider the different build-up rate and bending direction of the main and branched hole. Secondly, a mechanical model based on the elastic rod theory was established to calculate the force and deformation of drill strings in the wellbore and a re-entry coefficient was introduced to evaluate the reliability of the main hole re-entry. Moreover, the effects of tool face angle, build-up rate of wellbore, junction wall geometry, and motor structure on the re-entry coefficient are analyzed. Finally, the main controlling factors were analyzed to distinguish the influence degree of different parameters on the re-entry coefficient. From the results, the angle between the bending direction of the branched hole and the tool face of the BHA is the decisive factor in the process of the main hole re-entry. The BHA should be controlled so that the angle is greater than 90° as much as possible. If such angle is less than 90°, the change of wellbore build-up rate, junction wall geometry, and motor structure can be used to increase the re-entry coefficient, such as increasing the build-up rate of the branched hole, wellbore enlargement rate, depth of the slot in the junction wall, and ridge width of the junction wall. Meanwhile, decrease the angle of bent housing, distance between the bending point and the top of bit, and outer diameter of the body stabilizer of the motor can also increase the re-entry coefficient. Among the effects of re-entry coefficient, the main controlling factors are the bend point position and the angle of bent housing.

Orientation load prediction method based on randomness/stochasticity of multi-source parameters in coiled tubing drilling

Well trajectory control is always the key point of directional drilling. Downhole parameters measurements and BHA (bottom hole assembly) configuration and adjustment have the vital and coupling effect on realizing effective and efficient trajectory control. However, error exists universally in both of these phases. Compared with previous fixed value prediction models on controlling parameters prediction, uncertainty analysis based method will make the prediction results more reasonable and meaningful to control the BHA performance. With the consideration of the randomness of downhole multi-source parameters in coiled tubing drilling, an uncertainty prediction method for orientation load at a certain confidence level is proposed. Based on the beam-column theory, the probability and statistics theory is introduced and the distribution forms of main parameters are counted statistically. The probability density function and cumulative probability function of the orientation load prediction model when pump off and pump on in coiled tubing drilling are derived. The lognormal distribution has better correlation with the probability function of the orientation load, and the analysis on the confidence interval of the orientation load is described. Then, several relevant validation experiments are carried out, and the prediction of uncertain orientation load in coiled tubing drilling is also made. Several conclusions are made regarding to the field trial results. The randomness of weight on bit, friction coefficient of the interfacial between drill string and borehole wall or drill string and casing and tool face angle are the principal factors affecting the uncertainty of orientation load in coiled tubing drilling. The orientation load predicted with the uncertainty method is not a single curve or a single value, but an interval with a certain confidence level. The width of interval window is determined by the accuracy and precision of parameters information. The higher the confidence level is, the wider the predicted interval of orientation load and the larger the uncertainty range become. Compared with the predicted results of the uncertainty method, an error exists in the result of traditional single-value calculation method. The error varies with the change of weight on bit and formations and can be positive or negative. Meanwhile, retrieving more accurate principal original dada, e.g. WOB, formation properties, will make the uncertainty of the prediction lower. This orientation load prediction method is helpful to improve the efficiency of directional drilling in coiled tubing drilling.

Research on Application of BJZM-MWD1 Measurement While Drilling System

Measurement While Drilling system has been more and more widely used in directional drilling construction on the surface of mines. The system provides guidance for drilling construction, because it can transmit drilling parameter signals such as the deviation angle, azimuth and tool face angle collected by downhole tools to the ground through the mud, and then the signals are analyzed and decoded by computer software to restore the actual parameter data. In drilling construction, the self-developed BJZM-MWD1 Measurement While Drilling system encountered problems such as great variation in the amplitude and width of mud pulse signals and the interference of pulse signals. By filtering and amplifying the mud pressure generated by the pulse signal, and improving software decoding algorithm, the stability and reliability of the system have been greatly improved, meeting the requirements in site construction.

Tension–compression asymmetry of bilayer Ni/Ni3Al affected by dislocation formation–decomposition and twinning size

Molecular dynamics simulations were used to study the tensile and compressive properties of bilayer Ni/ Ni3Al. We found that: the tension–compression asymmetry behaviours of bilayer Ni/Ni3Al with different crystal orientations are different. The tension–compression asymmetry of different crystal orientations is result from different origins. For [001] crystal orientation, the formation of face angle dislocation in the γ' phase during tension, and no formation of face angle dislocation when compressed result in asymmetry. The reason for the [011] crystal orientation asymmetry is the twinning, and the twinning region during tension is larger than when it is compressed. [111] crystal orientation asymmetry is due to super dislocation decomposition. When dislocation is formed, the fault dislocation area during tension is smaller than that during compression, which results in the ability of preventing cross-slip when tension less than the compression state. The cross-slip is formed during tension, and the cross-slip does not occur during compression, exhibiting different tension–compression asymmetry behaviours. This study will provide theoretical guidance for the application of Ni-based single crystal alloys and further enhancement of their mechanical properties.

The effects of implant design, bone quality, and insertion process on primary stability of dental implants: an in-vitro study

The aim of this study was to analyse the maximum insertion torque (MIT) with respect to the implant thread face angle, bone quality and the insertion process. Two implants were designed and made: one with high face angle (HFA) and the other with low face angle (LFA). Bovine bones were classified, and then the MIT values of the implants were measured per round using standard protocol. Finally, three-way ANOVA was used to interpret the MIT values. For the main effects, MIT values (mean and standard error) of LFA (17.4 ± 0.7 N cm) and HFA implants (20.8 ± 0.7 N cm) were significantly different. The MIT values for the D4 (9.4 ± 0.6 N cm), D3 (19.1 ± 0.7 N cm), and D2 (28.8 ± 1.1 N cm) bones were significantly different. Considering the higher primary stability as an essential provision for immediate load implants, it is recommended to use implants featured with higher thread face angles.

Unapređenje procesa sabijanja kod četvorokrakih obradaka bazirano na kompjuterskom i fizičkom modeliranju

The method of upsetting of large ingots has been investigated in this work. The proposed method consists in upsetting of profiled workpieces with concave faces. An angle of the concave faces was 150°. A relative depth of the concave faces has been varied in range 15%…25% from workpiece's diameter. Strains effective and mean stresses in the longitudinal cross-section of the workpiece with concave faces after upsetting have been determined by FEM. A value of compressive stresses has been determined based on a parameter of the stress state. FEM allowed to find what a rational depth of the concave faces should be, which has to be 15 % from workpiece's diameter. Maximum closing of the internal defect take place for this depth of the concave faces. Results of the FEM have been tested by experimental investigations. It has been established that upsetting of the four-beam workpieces improved a quality of the massive parts.

Method for process monitoring of surface layer changes in turning of aluminium alloys using tools with a flank face chamfer

Abstract Lightweight materials can contribute significantly to an enhancement of energy and resource efficiency. In this context, the properties of the surface layer (e.g. residual stresses) influence the performance of machined parts considerably. However, the machining process often entails a change of the surface properties. Consequently, a predefined modification of the surface properties in final machining enables a highly efficient manufacturing of reliable lightweight components. For ensuring the required properties, the machining process has to be monitored. In the experimental investigations, stepped cylindrical specimens consisting of the aluminium alloy EN AW-2017 are machined by turning. The cutting speed is varied in the range from 50 m/min to 550 m/min. The depth of cut (0.2 mm) and the feed (0.05 mm) are kept constant. The influence of the chamfer angle of the flank face (0°, 5°, 10°, 15°) is analysed using cemented carbide indexable inserts. For process monitoring, the components of the resultant force are recorded by a dynamometer. Additionally, the voltage and the current between the tool and the workpiece resulting from the Seebeck effect are detected, enabling the measurement of the temperature near the shear zone. The geometrical properties of the machined surfaces are characterised using a tactile measurement instrument and a 3D laser scanning microscope. To determine the residual stresses, X-ray diffraction analyses of the machined surface are performed. The experimental results show that an increase of the cutting speed leads to higher Seebeck voltages between the tool and the workpiece due to elevated temperatures in the shear zone. Additionally, the surface roughness depth Rz and the built-up edge formation are reduced. Enlarging the chamfer angle results in increasing surface roughness values and decreasing absolute values of the tensile residual stresses in the tangential direction at the surface. The process monitoring allows for the implementation of real-time control adjustment of the surface layer properties during machining.

Balance Improvements and Golf Swing Kinematic Consistency with Eight Week Balance Intervention

The purpose of the study was to isolate the relationship between balance and swing kinematics for collegiate level male golfers. Eight National Collegiate Athletic Association (NCAA) Division I golfers completed an eight-week training program targeting improving balance. All golfers were assessed for postural stability and swing kinematics before and after the balance training program. Golfers completed 10 swings with a driver, and swing kinematics were measured using 3D motion capture (Qualisys AB). Postural stability results showed decreases in center-of-pressure (COP) deviation for single leg, eyes closed stance conditions were significant (p<0.05). Changes in Balance Error Scores (BES) were not significant (p>0.05) for any stance condition following training intervention. Range values (maximum-minimum) for club head speed (CHS), club path, and face angle stayed the same or decreased following the training intervention but were not significant (p>0.05). Key positions in the golf swing, including pelvis and torso angles at the top of the swing and impact were unaffected by the balance training (p>0.05). Pearson’s values indicated a low degree of correlation between postural stability and swing kinematic consistency, as measured by variance. While postural stability improved following golf specific balance training, individual swing kinematics and swing kinematics consistency were unaffected.

CFD Modelling of a Stepped Spillway with Various Step Layouts

A traditional stepped spillway is prone to cavitation risks. To improve its hydraulic behaviors, distorted step faces and pool weirs are devised. By numerical modelling, comparative studies are conducted to look into the flow features. The pressures on step surfaces of the unconventional layouts exhibit 3D distributions. Pool weirs are essential in increasing both the min. and max. pressure loads. Pressures on the downstream bed show a unique pattern for V- and inverted V-shaped models, with the extreme pressures at the sidewalls for the former and at the central plane for the latter. Symmetrical secondary flows are formed in V- and inverted V-shaped cases with different patterns. Distributions of turbulent kinetic energy suggest differences in flow motions in all cases. Furthermore, the relative energy loss of flat setups is ∼5.4% lower than that of the pooled ones with the same step face angle; inverting the face angle does not give rise to noticeable change. The results provide reference for relevant projects.

Energy Dissipation in Stepped Spillways with Different Horizontal Face Angles

Energy dissipation is one of the most important factors in choosing stepped spillways. However, very few studies have investigated energy dissipation with different horizontal face angles. In this paper, the realizable k-ε turbulent model was used to study the flow field, energy dissipation rates and turbulent kinetic energy and its dissipation rate for different stepped spillways with five horizontal face angles in the skimming flow regions. Results showed that the field and direction of the flow were changed by the horizontal face angles of the stepped spillway, which produced some unique characteristics and thus caused better energy dissipation. The fluctuation of free water surface will be larger with increasing horizontal face angles and the energy dissipation rate decreases with an increasing unit discharge and increases for the enlargement of the horizontal face angles. This conclusion could provide a reference for the relevant research of V shaped stepped spillways.

Summary of Modelling Safety Factors of Slope Stability in A Tar-Sand Quarry: A Case Study

This research studies the importance of slope stability during open-pit mining of tar sand within the Dahomey basin, Southwest Nigeria. It involved the geotechnical characterization of the layers of Laterites and Alluvium which it underlies. In addition, SLOPE/W software of the GeoStudio package was utilized for deducing and modeling the bench face angles which had higher safety factors, through the Morgenstern Price method of slices. It was discovered that the lateritic soil layer possessed higher values of unit weight, cohesion and internal frictional angle than those of the Alluvial Sand layer. Factors of safety were generated for bench face angles ranging from 10o to 90o at 1m, 4m and above 40m groundwater levels; over a 10m bench width and 6m bench height. However, for heavy equipment, a bench width of 20m and height of 6m were assumed. This resulted in factors of safety varying between 3.58 and 1.73 for bench face angles between 10o and 30o during higher precipitation (and water tables). Thus, this suggests that stable slopes predominate at bench face angles of 10o to 30o. This can be further enhanced when sufficient drainage systems are constructed.Â

The Development of a New Sensor for Tool Face Angle Based on Electrical Resistance

Trenchless technology is a type of construction that requires pipelines to be laid in a subsurface horizontal hole drilled by a trenchless drilling rig. To prevent drilling accidents during construction, the drilling trajectory needs to be controlled in real time according to the value of the tool face angle. However, existing tool face angle sensors cannot precisely control a trenchless drilling course due to a number of limitations such as low resolution, large temperature drift, and high requirements for accurate installation. In this regard, this paper presented a new tool face angle sensor based on the change in electrical resistance value. The tests mainly include four aspects, namely, accuracy, repeatability, resolution, and temperature drift. Numbers of tests showed that the measurement error was ±6 degrees, the repeatability was 2.54%, the minimum resolution was 6 degrees, and the temperature drift had no effect during the temperature changes from 0 to 80 degrees, which proved that the sensor is applicable for practical trenchless working conditions.

Parametric investigation for discrete optimal design of a cantilever retaining wall

In this paper, discrete design optimization of a cantilever retaining wall has been submitted associated with a detailed parametric study of the wall. In optimal design, the minimum wall weight is treated as the objective function. Through design algorithm, the optimal design variables (base width, toe width, thickness of base slab and angle of front face) yielded minimum structural weight of the wall and satisfied stability conditions have been determined for different soil parameter values. At the end, a detail parametric study searching the effect of change of soil parameters on the retaining wall design has been conducted with 120 optimized wall designs for different values; eight values of the angle of internal friction, three values of the unit volume weight and five values of wall heights. The obtained results from optimization analyses indicate that change of the angle of internal friction more effective than change of the unit volume weight on the optimal wall weight. Economic wall design with optimization analysis is achieved in a shorter time than the traditional method.

Optimization of a Commercial Variable Angle Accessory for Entry Level Users of Electrochemical Attenuated Total Reflection Surface-Enhanced Infrared Absorption Spectroscopy (ATR-SEIRAS).

An evaluation of several experimental aspects that can optimize electrochemical attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) performance using a commercially available, specular reflection accessory is provided. A comparison of different silicon single-bounce internal reflection elements (IREs) is made with emphasis on different face-angled crystal (FAC) options. Selection of optimal angle of incidence for maximizing signal and minimizing noise is shown to require consideration of the optical throughput of the accessory, reflection losses at the crystal surfaces, and polarization effects. The benefits of wire-grid polarizers and antireflective (AR) coatings on the IREs is discussed. High signal-to-noise ratios can be achieved by omitting polarizers, using an AR-coated FAC with a larger face angle, and working at angles of incidence close to the maximum throughput angle of the accessory.

Beam Dynamics Design of a Radio-Frequency Quadrupole and a Drift Tube Linac for a High-Intensity Proton Injector

We show the design results of beam dynamics on the injector for high-intensity proton accelerators. The injector can be utilized in a medical proton linac and accelerator driven system. The injector system consists of a 325-MHz RFQ (radio-frequency quadrupole) accelerator and a 325-MHz DTL (drift tube linac) accelerator. The injector has been designed to optimize the beam parameters to meet the required design goals. In this paper, we present a design study on the beam dynamics in the injector through beam tracking. We show the results of the beam dynamics study and cavity design study in the RFQ. The high-intensity RFQ accelerates the proton beam from 50 keV to 3 MeV with a peak beam current of 30 mA. The RFQ has a length of 3.839 m and Kilpatrick value of 1.76. We investigated ways to minimize the emittance growth caused by the space-charge effect and optimized achieve a high transmission and a small growth of emittance along the RFQ. The DTL with face angles of 3 degree and 10 degree in one tank accelerates proton beams from 3 MeV to 10 MeV and is 4.3 m long. Electromagnet quadrupoles (EMQs) are used as focusing elements in a Focusing-Defocusing-Focusing-Defocusing (FFDD) lattice scheme in the DTL. A quadrupole between the RFQ and the DTL, and 8 drift tubes (DT) in DTL are used for transverse matching in the DTL. We investigated the beam dynamics to achieve a high transmission and a small growth of emittance along the DTL. We also show the results of beam tracking simulations in the DTL. Our studies show that major parameters affecting on beam dynamics in the injector for a high-intensity proton linac are available.

Study of lifter wear and breakage rates for different lifter geometries in tumbling mill: Experimental and simulation analysis using population balance model

The lifter profile, mill speed and the amount of mill loading are the key elements influencing the load behavior, consequently the milling performance. In this paper, the effect of lifter face angle and height were studied for a lab scale ball mill. The effect of mill geometry on breakage rate and lifter wear rate was analyzed experimentally. A series of batch grinding tests were carried out using four different lifter (lifter I to IV) geometries and the rate of breakage was determined for each condition. Natural feed size of a top size 9.5 mm was ground in a Ø = 0.32 m test mill (Jb:40%, w/w: 68%, Nc: 55, 65, 75 and 85%). The torque was recorded against the wear measurement of each lifter. The results confirmed the phenomena that all the measured torque/power values decreased after a certain value of Nc, that is 75% in this study. Lifter IV produced the highest rate of breakage at Nc of 65–75% and the lowest wear. Based on the experiments, a simulation of an industrial mill (3.5-degree lifter face angle) was done using the estimated values. The results showed that, similar to the batch tests, Lifter IV (12 mm height, 22.5-degree face angle) may increase the breakage rate and fine particle generation. The overall value of SSE was calculated to observe the variability in milling experiments. The value obtained was 26.18, with an error 3.73%.

Simulation of nozzle position optimization based on single-phase flow

The numerical simulation on the lubrication of the complex gearbox was studied and an optimization for its injection lubrication system was carried out. Firstly, a pair of high speed gear test bench was built and related experiments were completed. The experimental results verified the correctness of the numerical simulation modeling method. Then the numerical model of the injection lubrication of the complex gear box was established, the simulation analysis was carried out. The results show that the overlong injection distance, the angle of the end face and the arrangement of the nozzle in the out of mesh side are not good for lubrication. And there is a trace in the center plane of the two meshing gear, along which the ejected oil will be under the least impact of the high speed airflow that driven by the rotating gears. When the nozzle axis is in the direction of the trace, the gear lubrication condition is the best.