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This paper aims to present the idea of an automatic control system dedicated to small manned and unmanned aircraft performing manoeuvres other than those necessary to perform a so-called standard flight. The character of these manoeuvres and the range of aircraft flight parameter changes restrict application of standard control algorithms. In many cases, they also limit the possibility to acquire complete information about aircraft flight parameters. This paper analyses an alternative solution that can be applied in such cases. The loop manoeuvre, an element of aerobatic flight, was selected as a working example.

This paper used theoretical discussion and breakdowns to create basics for designing structures of control algorithms. A simplified analytical approach was then applied to tune regulators. Research results were verified in a series of computer-based software-in-the-loop rig test computer simulations.

The structure of the control system enabling aerobatic flight was found and the method for tuning regulators was also created.

The findings could be a foundation for autopilots working in non-conventional flight scenarios and automatic aircraft recovery systems.

This paper presents the author’s original approach to aircraft automated control where high precision control is not the priority and flight parameters cannot be precisely measured or determined.

The paper aims to present an idea of automatic control algorithms dedicated to both small manned and unmanned aircraft, capable to perform spin maneuver automatically. This is a case of maneuver far away from so-called standard flight. The character of this maneuver and the range of aircraft flight parameters changes restrict application of standard control algorithms. Possibility of acquisition full information about aircraft flight parameters is limited as well in such cases. This paper analyses an alternative solution that can be applied in some specific cases.

The paper uses theoretical discussion and breakdowns to create basics for development of structures of control algorithms. Simplified analytical approach was applied to tune regulators. Results of research were verified in series of software-in-the loop, computer simulations.

The structure of the control system enabling aerobatic flight (spin flight as example selected) was found and the method how to tune regulators was presented as well.

It could be a fundament for autopilots working in non-conventional flight states and aircraft automatic recovery systems.

The paper presents author’s original approach to aircraft automatic control when high control precision is not the priority, and not all flight parameters can be precisely measured.

The purpose of this paper is to present the idea of automatic flight control algorithms capable of performing an Immelmann turn manoeuvre automatically. This is a case of a manoeuvre far removed from so-called standard flight. The character of this manoeuvre and the range of changes in the aircraft flight parameters restrict the application of standard control algorithms. Furthermore, the possibility of acquiring full and detailed information about the aircraft’s flight parameters is limited in such cases. This paper seeks to analyse an alternative solution that can be applied in some specific cases.

This paper uses theoretical discussion and breakdowns to create the basics for development of structures of control algorithms. A simplified analytical approach was applied to tune regulators and the results of the research were verified in a series of software-in-the loop computer simulations.

The structure of the control system enabling aerobatic flight (with the Immelmann turn as the selected example) was identified and the method for tuning the regulators is also presented.

It could serve as a foundation for autopilots working in non-conventional flight states and aircraft automatic recovery systems.

This paper presents the author’s original approach to aircraft automatic control when high control precision is not the priority and not all flight parameters can be precisely measured.

A three dimensional (3D) numerical modelling of filament assemblies has been developed in this study. The twist behaviour of the multifilament is simulated using the ABAQUS finite element package by modelling the yarns as 3D continuum elements. The migration of the filaments has been shown in a previous paper. In this study, we will describe a quantitative analysis of filament migration for different levels of twisting tension and torsion. The distribution of the filament orientation angle in accordance to the radial position and the axial position of the yarn are evaluated.

The purpose of this paper is to improve the manufacturing of a prosthetic acetabular shell by analyzing the main factors leading to failure during the selective laser melting (SLM) additive manufacturing (AM) process.

Different computer-aided design and computer-aided manufacturing processes have been applied to fabricate acetabular parts. Then, various investigations into surface quality, mechanical properties and microstructure have been carried out to scrutinize the possible limitations in fabrication.

Geometrical measurements showed 1.59 and 0.27 per cent differences between the designed and manufactured prototypes for inside and outside diameter, respectively. However, resulting studies showed that unstable surfaces, cracks, an interruption in powder delivery and low surface quality were the main problems that occurred during this process. These results indicate that SLM is an accurate and promising method for production of intricate shapes, provided that the appropriate settings of production conditions are considered to minimize possible limitations.

The contributions of this paper are discussions covering different issues in the AM fabrication of acetabular shells to improve the mechanical properties, quality and durability of the produced parts.

This paper aims to apply a robust methodology to establish relationships between user-configurable process parameters of commercial desktop stereolithography (SLA) printers and dimensional accuracy of a custom-designed test artifact.

A detailed response surface methodology study, Box–Behnken incomplete factorial design of four factors with three levels, was carried out to evaluate process performance of desktop SLA printers. The selected factors were as follows: printing orientation angle in x-direction, printing orientation angle in y-direction, position on build platform in spatial x-coordinate, position on build tray in spatial y-coordinate and layer thickness. The proposed artifact was designed to include 12 feature groups including thin walls, holes, bosses, bridges and overhangs. Two responses were associated with the features: the dimensional deviation according to the designed value and the minimum feature size.

Layer thickness was the most significant factor in 70% of the analyzed responses. For example, measurement deviation was reduced about 90% when cylindrical holes were printed with the lowest layer thickness. Further, in many cases, dimensional deviation was minimized for features at the center of the platform, where the beam cures the resin in a straight line. However, at distant positions, accuracy could be improved by compensating for beam deviation by changing the object orientation angle.

The findings of this study can serve, both generally and specifically, for SLA designers and engineers who wish to optimize printing process variables and feature location to achieve high-dimensional accuracy and further understand the many coupled considerations among part design, build configuration and process performance.

Additive manufacturing of polymer composites is a transformative technology that leverages the benefits of both composite material and 3D printing to produce highly customizable, lightweight and efficient composites for a wide range of applications.

In this research work, glass fiber-reinforced polylactic acid (PLA) filament is used to print the specimen via fusion deposition modeling process. The process parameters such as infill densities (40%, 50% and 60%) and raster angle/orientations (0°, 45° and 90°) are varied, and the specimens for tensile, flexural, impact, hardness and wear testing are prepared as per their respective ASTM standards.

The results revealed that with an increase in infill density, the mechanical properties of glass fiber-PLA specimens increase progressively. Optimal tensile properties and flexural properties are obtained at 0° and 90° raster angle orientations and 60% infill density. Minimum wear rate is achieved at 0° raster angle orientation and it increases at 45° and 90° raster angle orientations.

Using SEM, the microscopic analysis of the fractured specimen was analyzed to study the interface between the fibers and matrix and it indicates the presence of good adhesion between the layers at 60% infill density and 0° print orientation.

This paper aims to analyze the influence of rotated anisotropy on the stability of slope, the random finite element method is used in this study.

The random field is generated by the discrete cosine transform (DCT) method, which can generate random field with different rotated angles conveniently.

Two idealized slopes are analyzed; it is observed that the rotated angle significantly affects the slope failure risk. The two examples support the conclusion that when the orientation of the layers is nearly perpendicular to the slip surface, the slope is in a relative stable condition. The results of heterogeneous slope with two clay layers demonstrate that the rotated angle of lower layer mainly controls the failure mechanism of the slope, and the rotated angle of upper layer exhibits a significant influence on the probability of slope failure.

The method for rotated anisotropy random field generation based on the DCT has a simple expression with few parameters and is convenient for implementation and practical application. The proposed method and the results obtained are useful for analyzing the stability of the heterogeneous slopes in engineering projects.

The purpose of this paper is to propose a new trajectory planning algorithm for industrial robots, which can let the robots move through a desired spatial trajectory, avoid colliding with other objects and achieve accurate movements. Trajectory planning algorithms are the soul of motion control of industrial robots. A predefined space trajectory can let the robot move through the desired spatial coordinates, avoid colliding with other objects and achieve accurate movements.

The mathematical expressions of the proposed algorithm are deduced. The speed control, position control and orientation control strategies are realized and verified with simulations, and then implemented on a six degrees of freedom (6-DOF) industrial robot platform.

A fixed-distance trajectory planning algorithm based on Cartesian coordinates was presented. The linear trajectory, circular trajectory, helical trajectory and parabolic trajectory in Cartesian coordinates were implemented on the 6-DOF industrial robot.

A simple and efficient algorithm is proposed. Enrich the kind of trajectory which the industrial robot can realize. In addition, the industrial robot can move more concisely, smoothly and precisely.

This study aims to investigate the differences in spatial ability between students with a math learning disability and their normal peers.

To investigate these differences two groups, (60 students with a math learning disability) and (60 normal students) from fifth grade with a mean age (10.6 years) were administered with spatial ability test along with an IQ test. Students with a math learning disability were chosen using measures of the following: math learning disability questionnaire developed from learning disability evaluation scale – renormed second edition (LDES-R²) (McCarney and Arthaud, 2007) and the Quick Neurological Screening Test (Mutti et al., 2012), in addition to their marks in formal math tests in school.

Comparison between the two groups in four aspects of spatial ability resulted in obvious differences in each aspect of spatial ability (spatial relations, mental rotation, spatial visualization and spatial orientation); these differences were clear, especially in mental rotation and spatial visualization.

This paper contributes to gain more insights into the characteristics of pupils with a math learning disability, the nature of spatial abilities and its effect on a math learning disability. Moreover, the results suggest spatial ability to be an important diagnose factor to distinguish and identify students with a math learning disability, and that spatial ability is strongly relevant to math achievement. The results have significant implications for success in the science, technology, engineering and mathematics domain.