Innovative Construction of the AFPM-Type Electric Machine and the Method for Estimation of Its Performance Parameters on the Basis of the Induction Voltage Shape

The article presents an innovative construction of the Axial Flux Permanent Magnet (AFPM) machine designed for generator performance, which provides the shape of induced voltage that enables estimation of the speed and rotational angle of the machine rotor. Design solutions were proposed, the aim of which is to limit energy losses as a result of the occurrence of eddy currents. The method of direct estimation of the value of the rotational speed and rotational angle of the machine rotor was proposed and investigated on the basis of the measurements of induced voltages and machine phase currents. The advantage of the machine is the utilization of simple and easy-to-use computational procedures. The acquired results were compared with the results obtained for estimation performed by using the Unscented Kalman Filter (UKF).

Experimental Study on Gasketed Bell and Spigot Joint Behaviour of Lined-Corrugated HDPE Pipe Subjected to Normal Fault

Although structural response of pipelines has been studied in relation to different geohazards, few studies have focused on the behaviour of flexible pipeline joints. In this paper, the response of a bell and spigot joint in a 600 mm diameter lined-corrugated High Density Polyethylene (HDPE) pipe was investigated under the differential ground movements imposed using a facility that simulates a normal fault. Two experiments were undertaken in this facility. In the first experiment, the kinematic responses of the pipe joint (i.e. axial, shear displacements and rotational angles) were measured using Particle Image Velocimetry (PIV) and string potentiometers. Strains were also monitored using optical fibres. In the second experiment, the pipe was sealed and leakage of the joint was captured through monitoring of internal vacuum pressure of the pipe. The results show that axial shortening, rotational angle and shear displacement of the pipe joint increased with increasing fault offsets. The joint began to leak when axial shortening, rotational angle and shear displacement of the pipe joint were 0.65 mm, 0.44° and 3.40 mm, respectively, and the joint clearly lost its functionality when those values were 0.85 mm, 0.58° and 4.32 mm.

Study of the Cone-Shaped Drogue for a Deep-Towed Multi-Channel Seismic Survey System Based on Data-Driven Simulations

A drogue is used to stabilise and straighten seismic arrays so that seismic waves can be well-received. To embed the effect of a cone-shaped drogue into the numerical modelling of the deep-towed seismic survey system, one surrogate model that maps the relationship between the hydrodynamic characteristics of the drogue and towing conditions was obtained based on data-driven simulations. The sample data were obtained by co-simulation of the commercial software RecurDyn and Particleworks, and the modelling parameters were verified by physical experiments. According to the Morison formula, the rotational angle, angular velocity, angular acceleration, towing speed, and towing acceleration of the drogue were selected as the design variables and drag forces and aligning torque were selected as the research objectives. The sample data of more than 8500 sets were obtained from virtual manoeuvres. Subsequently, both polynomial and neural network regression algorithms were used to study these data. Finally, analysis results show that the surrogate model obtained by machine learning has good performance in predicting research objectives. The results also reveal that the neural network regression algorithm is superior to the polynomial regression algorithm, its largest error of mean square is less than 0.8 (N2/N2 mm2), and its R-squared is close to 1.

Analysis of rotation capacity of a novel 2R1T mechanism based on origami of thick panels

A foldable and symmetrical lower-mobility parallel mechanism was proposed based on Waterbomb origami of thick panels. It consists of a moving platform, a base plate and three deployable foldable legs between moving platform and base plate. Firstly, constraint wrenches of each leg were formulated based on screw theory and the results illustrated that the moving platform is in possession of two degrees of orientation freedom and one translational degree of freedom. Secondly, it was approved that base and moving platform are always symmetrical about a middle plane and the moving platform can rotate continuously about any axis chosen freely on this plane. Solving models including forward and inverse position problems were established to determine the maximum rotational angle and workspace. Finally, performance indexe of maximum rotational angle of the PM was analyzed, and effects of two structural variables to the performance were summarized. Conclusions obtained can provide a theoretical basis for the structural design and engineering application of this 2T1R parallel mechanism.

Calculation Method of Working Rotational Angle of Automobile Transmission System and Its Applications

The working state and operating parameters of the automobile transmission system play a key role in the vehicle noise and vibration performance. Based on the basic calculation method of relative rotational angle, this paper proposes two methods for calculating the working rotational angle and torsional stiffness of the transmission system, which can effectively obtain the key information of the transmission system under the vehicle operating state. The working rotational angle, whose initial angle should be corrected by the average angle in the neutral gear coasting condition, can reflect the actual working state of the torsional vibration damper effectively. And the accuracy of the linear torsional stiffness obtained will be above 90%. Both simulation and experimental analysis results show that these two proposed application methods have high calculation accuracies and engineering feasibility.

Development of Double-Sided Multipoint Press CNC and Operational Technology for Producing Freeform Molds

Many studies concerning the precision manufacturing of freeform concrete panels have been conducted, however, this process remains labor intensive taking significant amounts of time and cost. In particular, the precision in the shape of the panels produced tends to be low because of the manual work involved in producing the curves of those panels. This study documents the development of mold production technologies that can be used to produce precise curved surfaces on the upper and lower parts of a mold for freeform concrete panels. A double-sided multipoint press CNC (computer numerical control) produces curved upper and lower surfaces of a mold without the need for manual work, while the operational technology we developed to control this tool enhances the precision of the curves created. The precision of these technologies was verified through experiments. The difference between the shapes designed and those produced were found using 3D scans and quality inspections. Unpredictable errors can occur due to the size of certain curvatures, the elasticity of the silicone plate, and the rotational angle of the joints of the rods supporting the surfaces. To minimize errors, shape compensation was carried out through reverse engineering, leading to a maximum error of 2.887 mm, which is within the allowable error. The results achieved in this study are a significant step toward technologies that will produce increasingly precise freeform concrete panels.

The Influence of Laboratory Scanner Versus Intra-Oral Scanner on Determining the Implant Axis by Using Three Different Scan Abutments

Background: The purpose of this in vitro study was to compare the implant axis’ spatial position and orientation by using laboratory scanner versus intra-oral scanner with three different scan abutments. Methods: A 3D model was printed with an internal hex implant analog in the place of teeth 35#. Three standard scan abutments were used: MIS (two-piece titanium), AB (two-piece PEEK and titanium base) and ZZ (one-piece PEEK). Each scan abutment was scanned 30 times by TRIOS E3 (laboratory scanner) and 30 times by Omnicam (intra-oral scanner). For each scan, an STL (stereolithography) file was created, and the spatial characterization of each scan abutment was measured in the X, Y, Z coordinates, and rotational and longitudinal angles. The comparison between all the scans was conducted by superimposition of the STL files, using a 3D software. A t-test and Wilcoxon signed-rank test were used. (p < 0.05) Results: Only the MIS scan abutment showed no statistical difference in the X and Z axes. (p < 0.05). All other scan abutments showed a statistical difference in all axes. The rotational angle of the AB scan abutment was twice the angle of the MIS and ZZ scan abutments. Conclusions: All three scan abutments showed a rotational deviation of the implant axis between the laboratory scanner and the intra-oral scanner. The AB scan abutment showed the greatest deviation (1.04 degrees) while the other two abutments showed deviations of about half a degree in relation to the laboratory scan abutment. There is a need for further studies which will examine the influence of geometry, material, and scan abutment parts on the accuracy of the scan obtained.

Catechin Extracted from Uncaria gambier Roxb for Nanocatechin Production: Physical and Chemical Properties

This research reports nanoparticles or nanocatechin produced from catechin extracted from gambier and the differences between the properties of the extracted catechin and nanocatechin. The study began with the preparation of >95% pure catechin through successive extraction. The catechin obtained was converted to nanocatechin with a high-speed homogenizer on a 1% suspension of catechin in water at 12,000 rpm for 30, 45, 60, 75 or 90 minutes. Results showed average diameters of the nanocatechin 90-minute homogenized colloids were then dried with a spray dryer so physical and chemical properties could be compared with those of the raw extracted catechin. Catechin content, water content, pH, refractive index, density, molecular weight and rotational angle were unaltered. Appearance, solubility, thermal properties, highest absorbance wavelength and antioxidant activity were measured. Initial degradation temperature and antioxidant activity of nanocatechin were higher than those in the originally extracted catechin.

Improvements to torque versus tension relationship considering nut dilation effects

Torque as a tightening method is a simple technique that can be used to tighten a bolt to a given pre-load. Therefore, it is important to theoretically derive an accurate torque vs tension relationship for threaded fasteners as this would enable the industry to achieve a reliable pre-load. Various attempts were made to develop a complete theoretical relationship between torque and tension. Due to the thread angle there exists a nut dilation force causing the nut to expand radially out wards. This effect is more prominent in nuts with smaller height (Style 0 hex nut, refer ISO 4035 1 ). This nut dilation force creates a combined frictional effect with the drive torque thus affecting the torque tension relationship. This paper proposes a novel 3D formulation for torque tension relationship taking into consideration the nut dilation effect. This paper further develops new formulae for tightening and loosening torque, retaining torque, tension vs nut rotational angle relationship as well as formula for nut dilation force for both tightening and loosening.