Suppose that you have a piece of workshop equipment—an oven, say—weigh‐ing several tons, that needs to be moved across a rough concrete floor. Just to make things more difficult, the headroom is only a few inches more than the height of the equipment, and there is no room for a hoist, a crane, or any other large moving gear. The floor is too rough to roll the oven on any form of wheels, and sliding it is out of the question.
A design study is carried out for an air cushion vehicle based on a specification giving it a performance comparable with cars of similar power and size, and compatible…
A design study is carried out for an air cushion vehicle based on a specification giving it a performance comparable with cars of similar power and size, and compatible with current road conditions. Preliminary examination of requirements leads to the adoption of a plenum chamber lift system and ducted fan propulsion, powered by a single piston engine. Care is taken to provide the vehicle with the responsive and accurate control necessary on the road. Performance calculations are carried out, enabling it to be compared with wheeled road vehicles. It is found that its cruising speed and fuel economy are better than its wheeled counterpart, due to the low resistance to motion offered by the air cushion, while its turning performance is definitely inferior.
An analysis is made or the basic principles which govern the operation of those air‐cushion devices otherwise known as ground‐effect machines (GEMs). Most of these…
An analysis is made or the basic principles which govern the operation of those air‐cushion devices otherwise known as ground‐effect machines (GEMs). Most of these vehicles can be defined as machines which operate in close proximity to the earth's surface without ever physically touching it because they are always separated from it by a cushion or a layer of air, however thin; as a consequence, propulsion and control of GEMs must be of an aerodynamic nature. The only machines not covered by this definition are special types of over‐water GEMs. It is proposed to establish six main categories of GEMs from which all other possible configurations could be evolved by proper combination of the basic types. For each of these six configurations, a critical biographical survey is made and some comparative features are pointed out. The overall picture is one of great complexity because of the large number of parameters involved. This points out the danger of a ‘hardware’ approach to the GEM problem until a firm base of comprehensive research has been established. At the present time, the emphasis placed on the annular jet seems justified, inasmuch as the annular jet represents a good compromise between versatility, simplicity and performance.
This paper describes the development and the performance characteristics of a pneumatic proximity‐to‐tactile sensing device for automated recognition of manufacturing parts within flexible manufacturing environments. This tactile sensing device utilises a densely packed line array of IC piezoresistive pressure sensors, providing continuous variable back pressure output. The sensing elements incorporate a corresponding line matrix of air jets which form an air cushion between the sensing plane and the target when striking the object of interest. The back pressure output levels form the basis for the tasks of object detection and recognition. The system described is a research prototype and has been evaluated on a simple test rig: in this form it is not at a stage where it can be applied to a recognition situation on the shop floor.
This paper aims to summarize researches conducted related to functional textiles for prevention of pressure ulcers and critical analysis of the outcomes to pave path for…
This paper aims to summarize researches conducted related to functional textiles for prevention of pressure ulcers and critical analysis of the outcomes to pave path for the future research in this area for benefit of the patients. Pressure ulcers, also known as bed sores, pressure sores and decubitus ulcers, are localized areas of tissue damage that develop due to pressure usually over a bony prominence. A standard hospital mattress has an interface pressure of 100 mmHg which can result in pressure ulcers unless repositioning occurs at regular intervals. Moisture accumulation on the skin is an important physical factor predisposing a patient to the occurrence of pressure ulcers and tissue breakdown. The disability leads to several requirements of functional clothing and textile products. The textiles play a variety of roles in this concern, from simply having good aesthetic appearance to preventing life threatening risks. An ideal support surface prevents pressure ulcers by providing pressure redistribution and maintaining a healthy skin microenvironment. The use of the textiles for the care of elderly disabled and bedridden persons can play an important role, as their quality of life can be improved by making use of functional and good-looking textiles.
This review paper aims to summarize researches conducted related to functional textiles for prevention of pressure ulcers and critical analysis of the outcomes to pave path for the future research in this area for benefit of the patients.
In the past years, there have been several functional textiles developed for the prevention of pressure ulcer. They are designed to maintain proper microclimate around patient skin. Sheepskin is one of the oldest used bed overlays which prevent pressure ulcer but its prolonged use leads to uneasy feeling for the patient. A sensor in bed for pressure detection is one of the good alternatives as it provides proper indication on when to change the position of the patient so that the pressure can be shifted and ulcers is prevented. These sensors are costly and complex to setup so for common man they are not easily available. Multilayer textiles on the other hand are complex to make as the properties are dependent upon the fiber content, yarn structure, fabric structure and technique of layering them together. Spacer fabric provides good air and moisture permeability, but there is a scope to study this type of fabric by varying the fibers type and thickness of the spacer fabric. A bedding material which is not much complex and can be easily purchased and used by common man for in-house usage is the need of the hour.
There is no comprehensive review available regarding research in this area with critical analysis of the outcomes for future study.
THE public demonstration of the SRN‐I Hovercraft has aroused great interest. Without entering into sterile argument as to whether or not it is an aircraft we propose to…
THE public demonstration of the SRN‐I Hovercraft has aroused great interest. Without entering into sterile argument as to whether or not it is an aircraft we propose to give a few details of it and its origins and future.
UNTIL 1957, Mr C. S. Cockercll had been working unsponsored on the possibilities of vehicles, capable of travelling over land and water, supported on a pressurized cushion of air, and to these vehicles he gave the name Hovercraft. The Ministry of Supply at that time commissioned a programme of assessment and research but did not pursue the possibilities further, so Mr Cockercll appealed directly to the National Research Development Corporation for assistance.
The mainstream of current research work in array tactile sensors concentrates on using a soft compliant membrane as a means of transmitting the effect of variable external stimuli to the discrete sensing elements. The soft compliant devices are usually made of a thin flexible substrate such as pressure sensitive pads, conductive materials, conductive coatings, piezoelectric polymers or elastomers. A large number of tactile sensor designs using these types of materials have been investigated by researchers. These include the use of anisotropically conductive silicone rubber (ACS), sponges containing carbon particles or felted carbon fibres, piezoelectric polymers such as polyvinylidene fluoride (PVF2) and conductive elastomers such as Dynacom materials consisting of silicone rubber mixed with metallic compounds.
All measurements of EHD film thicknesses were carried out in simulated test machines. This study uses an actual bearing. A test rig which used a 65mm bore radial…
All measurements of EHD film thicknesses were carried out in simulated test machines. This study uses an actual bearing. A test rig which used a 65mm bore radial cylindrical roller bearing was constructed with a specially designed sapphire window in the outer track. Full loads, and speeds to 3000 rpm were applied. With specially polished rollers and chromic oxide coating on the window excellent interferometric film thickness measurements were found possible. A Xenon flash lamp was used and a Xenon Iaserof0–50pps,pulse half width of 150ns and peak power of 100 watts was developed for this research. A microscope and 35mm camera as well as video tape were used for recording results. Arrangements were made to study any chosen roller and the side of the bearing was also open to view. First the film measurements, when corrected for inlet zone viscous heating, agreed admirably with theoretical predictions for mid and exit film thickness. The effect of inlet boundary length on the film was then investigated in some depth. Studying the effect of the multiple roller system, a number of techniques were used to demonstrate that the inlet boundary length, which controls the lubricant film thickness, was itself controlled by the film thickness between the rollers and track in the unloaded zone. The ribs of oil, formed at either edge of the roller, are only secondary sources of oil for replenishment of the inlet film. It is in fact usual (as shown by the convex shape of the inletzone) for oil to feed out of the inlet zone into the ribs. Oil globules were sometimes observed riding on an air cushion at the entry to the roller‐track conjunction, though completely inoperative as providers of oil.