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Rapid prototyping (RP) techniques are being increasingly used to manufacture injection molding and die casting core and cavity sets, known as tools, and for other tooling‐related parts, such as EDM electrodes. This paper presents a STL‐based finish machining technique for tools and parts made using RP techniques in order to achieve the tight tolerance and surface finish requirements necessary for tooling applications. Rotate, scale, translate and offset algorithms are used to pre‐process the 3D model prior to its manufacture. A machining strategy of adaptive raster milling of the surface, plus hole drilling and sharp edge contour machining, is developed to finish the parts and tools after fabrication using RP. Finally, a benchmark part was designed and fabricated using the above‐mentioned strategies and the results show the effectiveness of the developed software.

This paper presents a unique method to recognize circular holes from 3D models in the STL format. The topological information generated by this method enables identification of holes and tool path generation for holes which should be drilled rather than milled.

A method based on a set of developed algorithms is used to identify closed loops from a STL model, identify which closed loops correspond to cylindrical holes, find hole orientations, locations and diameters, and calculate the depth for the recognized holes. The developed procedure and algorithms have been implemented in Visual C++ to illustrate the efficacy of the method.

The implementation results showed that the developed algorithms can successfully recognize circular holes of differing sizes on both simple and complex surfaces, and in any orientation. Tool paths can thus be generated from STL models to more efficiently and accurately machine circular holes.

The developed method requires that at least one simple closed loop exist for each potential hole.

A new and unique hole recognition method for use with STL models was developed. This method is useful for accurately and efficiently machining parts with circular holes from STL models as well as finish machining near‐net shape parts with circular holes created using rapid prototyping.

IS there anything magic about the shape of a wing section? Asked to sketch the profile of a wing on the back of an envelope, one would have no difficulty in representing a shape which would probably, for most purposes, be adequate. Assuming this generalization to be true—perhaps it is a rather rash one—one might equally well question the need for an article on aerofoil design, or indeed the need for the long and painstaking research which, over the years, has been conducted on this particular subject. But it is this same research which, in the long run, has resulted in the recognition of certain general rules relating to aerofoil geometry, which are now taken so much for granted that they would probably be embodied in one's preconceived notion of what a wing section should look like. Recently, also, rather complicated theoretical techniques have made possible the design of profiles which, if manufactured faithfully and carefully in each detail, can provide a performance which is considerably better than any more arbitrary shaping to general rules would produce. Finally, of course, one must recognize that there are exceptional conditions where the application of conventional ideas is inadvisable, and where theoretical and experimental research is needed to suggest what is more appropriate. This article will be concerned for the most part with amplifying these remarks; but, by and large, it must be admitted at the outset that we cannot point to any revolutionary discontinuities in the progress of aerofoil design such as have characterized advances in the means of aircraft propulsion, or structural design.

Part I—Constant Chord Blades 1. Summary Rotor/fuselage clearance is the most fundamental design consideration when laying out a new project, and it is essential to estimate this accurately at a very early stage. When centrifugal force droop stops are fitted to a rotor, the design criterion is usually the effect of a sharp‐edged down gust impinging on the rotor when it is not generating thrust; for example, whilst running‐up on the deck of an aircraft carrier. In this paper the dynamics of blade flapping motion are developed and a method for rapidly obtaining maximum gust deflexion is presented in the form of a Data Sheet (FIG. 5). This enables the maximum deflexion in a gust to be determined with no calculation. The solution obtained is exact; hitherto the only attempts to calculate gust deflexion known to the writer have developed an approximate equation of motion for the blade, and offered the Particular Integral as a sufficiently accurate solution. It is shown in Part II of this paper that this can be very misleading, and undcr‐estimates the true deflexion. In preliminary project design, the blade inertia is, of course, unknown. It is shown that this is a function of the coning angle and CL, basic only, probably the two most fundamental design parameters.

It is clear that for satisfactory service and resistance to corrosion, it is necessary not only to choose the right metal to be electrodeposited, and the right thickness of deposit, but also to ensure that the design of the basic article to be plated is such that a reasonably uniform deposit can be achieved without too much difficulty. The more complex the shape to be plated, the higher will be the cost, either because the total weight of metal over the whole article will have to be greater in order to provide the minimum thickness in the most difficult places, or because special plating jigs and anodes will be required to achieve a uniform deposit. The designer should therefore strive to avoid deep or narrow recesses, sharp edges and corners, sharp points, and generally complex shapes; he should aim to provide relatively simple shapes without sudden changes of contour or cross‐section, and generous radii on all corners and edges, both external and re‐entrant. Ideally, the worse the throwing power of the solution to be used for electroplating, the more simple should be the shape to be plated. Fig. 1 illustrates some of the points mentioned.

Shadows, the common phenomena in most outdoor scenes, bring many problems in practical image processing. Shadow detection and removal, especial in uncalibrated outdoor image, is still a difficult problem. The purpose of this paper is to detect and to remove shadows in single outdoor image based on retinex theory.

The shadow extraction algorithm originates from a simple idea that the human‐vision‐based retinex has the natural ability to enhance the shadow regions of an image no matter it is penumbrae or umbrae. Shadows are detected by comparing the retinex‐enhanced images with original images in the paper. The shadow removal algorithm in the paper deals with the shadow regions and non‐shadow regions in the images separately using the retinex enhancement algorithm. Through adding smooth light forcibly to shadow edges and introducing shadow edge masks, the authors reduce the effects of shadow edges in shadow removal processing.

Some real single outdoor images with the umbra regions and those with penumbra regions are both experimented in the paper. Experimental results validate the feasibility of the approach.

The approach proposed here does not use any special prior knowledge and assumptions. The feasibility of this method is testified for detecting and removing both penumbrae and umbrae in the outdoor images.

A nut bolt joint is a primary device that connects mechanical components. The vibrations cause bolted joints to self-loosen. Created by motors and engines, leading to machine failure, and there may be severe safety issues. All the safety issues and self-loosen are directly and indirectly the functions of the accuracy and precision of the fabricated nut and bolt. Recent advancements in three-dimensional (3D) printing technologies now allow for the production of intricate components. These may be used technologies such as 3D printed bolts to create fasteners. This paper aims to investigate dimensional precision, surface properties, mechanical properties and scanning electron microscope (SEM) of the component fabricated using a multi-jet 3D printer.

Multi-jet-based 3D printed nut-bolt is evaluated in this paper. More specifically, liquid polymer-based nut-bolt is fabricated in sections 1, 2 and 3 of the base plate. Five nuts and bolts are fabricated in these three sections.

Dimensional inquiry (bolt dimension, general dimensions’ density and surface roughness) and mechanical testing (shear strength of nut and bolt) were carried out throughout the study. According to the ISO 2768 requirements for the General Tolerances Grade, the nut and bolt’s dimensional examination (variation in bolt dimension, general dimensions) is within the tolerance grades. As a result, the multi-jet 3D printing (MJP)-based 3D printer described above may be used for commercial production. In terms of mechanical qualities, when the component placement moves from Sections 1 to 3, the density of the manufactured part decreases by 0.292% (percent) and the shear strength of the nut and bolt decreases by 30%. According to the SEM examination, the density of the River markings, sharp edges, holes and sharp edges increased from Sections 1 to 3, which supports the findings mentioned above.

Hence, this work enlightens the aspects causing time lag during the 3D printing in MJP. It causes variation in the dimensional deviation, surface properties and mechanical properties of the fabricated part, which needs to be explored.

This study aims to investigate the effects of propeller locations on the aerodynamic characteristics of a generic 55° swept angle sharp-edged delta wing unmanned aerial vehicle (UAV) model.

A generic delta-winged UAV model has been designed and fabricated to investigate the aerodynamic properties of the model when the propeller is placed at three different locations. In this research, the propeller has been placed at three different positions on the wing, namely, front, middle and rear. The experiments were conducted in a closed-circuit low-speed wind tunnel at speeds of 20 and 25 m/s corresponding to 0.6 × 10⁶ and 0.8 × 10⁶ Reynolds numbers, respectively. The propeller speed was set at constant 6,000 RPM and the angles of attack were varied from 0° to 20° for all cases. During the experiment, two measurement techniques were used on the wing, which were the steady balance measurement and surface pressure measurement.

The results show that the locations of the propeller have significant influence on the lift, drag and pitching moment of the UAV. Another important observation obtained from this study is that the location of the propeller can affect the development of the vortex and vortex breakdown. The results also show that the propeller advance ratio can also influence the characteristics of the primary vortex developed on the wing. Another main observation was that the size of the primary vortex decreases if the propeller advance ratio is increased.

There are various forms of UAVs, one of them is in the delta-shaped planform. The data obtained from this experiment can be used to understand the aerodynamic properties and best propeller locations for the similar UAV aircrafts.

To the best of the author’s knowledge, the surface pressure data available for a non-slender delta-shaped UAV model is limited. The data presented in this paper would provide a better insight into the flow characteristics of generic delta winged UAV at three different propeller locations.

Creases are marks that are created and left in a fabric during garment wear. Pressing is a process to flatten garment panels and sharpen garment edges and pleats. To minimize crease, the fabric should recover after pressing without creating a creased edge. Whereas, good pressing performance means the creased edge stays sharp after pressing. Good crease recovery and pressing performance appear contradictory. However, crease recovery and pressing performance are different as creases are formed during wear and pressing is carried out using pressing equipment such as iron, pressing machines, etc. The condition, i.e. temperature and humidity, under which the creases are formed in wear and pressing are very different. The latter has much higher temperature, pressure and humidity. This paper reports on an experimental investigation on the relationship between the crease recovery and pressing performance of wool and other fabrics. It was found that there are only generally weak to moderate relationships between the crease recovery as measured by the Shirley Crease Recovery Tester and the pressing performance as measured by the Siro‐Press Tester. The characteristics of wool fabrics, which have both good crease recovery and pressing performance, are identified. This study is a step towards fabric engineering.

THE trend of design in the modern aeroplane has been toward improved performance realised through external cleanness. It is apparent that the number of essential units comprising a modern aeroplane is nearly a minimum at the present stage of the art, and it appears also that the possibilities of further striking reductions in the drag of these units, due to change in form or shape either individually or in combination, are not great.