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Defines a vacuum and gives some basic facts about it, including an explanation of vacuum force and air pressure. Describes the three main applications of vacuum; low range, industrial and scientific and gives examples of uses. A vacuum can be created mechanically or by compressed air: discusses the advantages and disadvantages of mechanical vacuum pumps and compressed air‐driven ejector pumps. Concludes with a brief look at vacuum in relation to altitude.

Rotary high‐vacuum pumps are oil‐lubricated. The lubricating oil acts as a seal against atmospheric pressure, and to enable it to do this the pump is normally submerged, or virtually submerged, in the oil. In the course of operation of the pump, the oil inevitably becomes contaminated with substances extracted from the system under evacuation. This complicates the questions involved in selection of the oil and has given rise to a number of remarkable devices to limit the accretion of contaminants.

HIGH vacuum engineering has made rapid strides within the last decade for applications within many branches of science and engineering, including metallurgy, general engineering, optics, cryogenics, electronics, and, of course, aeronautics and astronautics. It is the aim of this article to describe briefly the techniques involved in high vacuum engineering and to describe some of the equipment being produced by one of the British companies occupying a leading position in this field—Bir‐Vac Ltd.

The purpose of this paper is to describe the design and construction of a custom‐built low‐cost thermal vacuum chamber (TVC) for spacecraft environmental testing and verification. The paper provides detailed analysis and an insight into the design and development of the chamber. The chamber was specifically constructed for carrying out the thermal and vacuum environmental tests in a 16″ dia × 16″ long horizontal thermal vacuum chamber. The chamber is constructed using a combination of mechanical (roughing) pump and turbo‐molecular pump, used to pump the chamber down to 10⁻⁵ Torr and a combination of radiation heaters and nitrogen gas is used to vary the temperature within the chamber from +80 to −50°C.

The TVC equipment is built as part of the picosatellite and nanosatellite program at Space Systems Research Laboratory of Saint Louis University. The equipment is built at a low cost and is suited for testing an entire picosatellite and several components and subsystems of nanosatellite simulating thermal and vacuum conditions similar to space environment. The different main parts of the equipment are described in a way which explains the choice of construction and partly makes it possible to replicate similar equipment.

The TVC equipment is successfully used to simulate the thermal and vacuum conditions of space similar to the conditions experienced by a picosatellite or nanosatellite in low earth orbit.

The design and construction of TVC in this paper have broader implications and can be a platform for future research on low‐cost TVC. This equipment can be utilized in the research areas of electronics and communications, biology and medicine to name a few. Thermal and vacuum experiments on several astro‐biological experiments can be performed.

The paper is intended to be a source of inspiration for industrial or academic space research laboratories which would like to design and construct a similar test‐equipment, instead of investing expensive commercially available alternatives.

The paper discusses in detail, the simplified cost‐effective approach of constructing TVC and also outlines the various issues to be considered. The TVC equipment is custom‐built and is described in an easily understandable way, which makes this a helpful paper for those who wish to produce similar equipment. This will be the only known manuscript in the literature to detail the design and construction of low‐cost, economical TVC.

Glass-cleaning robots were developed to perform the difficult, time-consuming and dangerous job of cleaning windows that had traditionally been done by humans. The wiping mechanism is the most important functional component of a glass-cleaning robot, which indirectly affects the design of the adsorption and transport mechanisms. This study aims to compare two types of wiping mechanisms – the drag-wiper and roller-wiper –through an analysis and an actual experiment, providing theoretical and measured data that can be applied to the optimization of the design of future glass-cleaning robots.

The authors undertook a theoretical force and energy consumption analysis of glass-cleaning robots and, based on the obtained results, undertook an analysis the two wiper types. They verified the theoretical analysis by conducting several experiments including studying the relationship between a wiper’s friction force and rotational speed, measuring the contact normal forces of the suckers, wiper and crawlers relative to the glass wall, measuring the energy consumed to drive the robot and studying the relationship between the vacuum pump’s power consumption and the adsorption force. The authors also compared the wiping efficacy of the drag-wiper robot and roller-wiper robot.

The drag-wiper offers the advantages of simplicity while being able to wipe the area around the edge of a window frame. Meanwhile, the use of a roller-wiper not only improves the robot’s driving performance and reduces the required adsorption force but can also reduce the amount of energy consumed to drive both the robot itself and also the vacuum pump; in addition, the roller-wiper is more flexible and energy- and time-efficient when dealing with dirt that is difficult to remove.

This study has, through a detailed analysis of the advantages and disadvantages of a drag-wiper and roller-wiper robot, from the three aspects of force analysis, energy consumption and wiping efficacy, obtained theoretical and measured data that can be applied to the optimization of the design of future industrial and household glass-cleaning robots.

The purpose of this paper is to show how to precisely control the liquid resin coating thickness in stereolithography (SL).

A vacuum adsorption coating equipment and technology are developed to precisely control the liquid resin coating thickness in SL. Dual‐electrode device is used, so adsorption can be precisely controlled and the electrode polarization can be avoided.

It turns out that the apparatus can control coating thickness effectively, and thickness uniformity is increased remarkably, which induces the standard deviation thickness decrease from 0.00547 to 0.00243 mm, and efficiency of rapid prototyping production increase by 53 percent.

The paper demonstrates that the apparatus can control coating thickness effectively.

This paper aims to present a multi-material additive manufacturing (AM) process with a newly developed curing-on-demand method to fabricate a three-dimensional (3D) object with multiple material compositions.

Unlike the deposition-on-demand printing method, the proposed curing-on-demand printheads use a digital light processing (DLP) projector to selectively cure a thin layer of liquid photocurable resin and then clean the residual uncured material effectively using a vacuuming and post-curing device. Each printhead can individually fabricate one type of material using digitally controlled mask image patterns. The proposed AM process can accurately deposit multiple materials in each layer by combining multiple curing-on-demand printheads together. Consequently, a three-dimensional object can be fabricated layer-by-layer using the developed curing-on-demand printing method.

Effective cleaning of uncured resin is realized with reduced coated resin whose height is in the sub-millimeter level and improved vacuum cleaning performance with the uncleaned resin less than 10 µm thick. Also, fast material swapping is achieved using the compact design of multiple printheads.

The proposed multi-material stereolithography (SL) process enables 3D printing components using more viscous materials and can achieve desired manufacturing characteristics, including high feature resolution, fast fabrication speed and low machine cost.

THE firm of Jessop‐Saville Ltd., which dates back to 1774, has become well established as a supplier of special steels and alloys. Their progress in this field has been maintained only by continual research and a readiness to adopt new techniques and equipment.