Search results

This paper aims to simulate a punch shear test of partly consolidated ice ridge keel by using a three-dimensional discrete element method. The authors model the contact forces between discrete ice blocks with Hertz–Mindlin contact model. For freeze bonds between the ice blocks, the authors apply classical linear cohesion model with few modifications. Based on punch shear test simulations, the authors are able to determine the main characteristics of an ice ridge from the material parameters of the ice and freeze bonds.

The authors introduced a discrete model for ice that can be used for modelling of ice ridges. The authors started with short introduction to current status with ice ridge modelling. Then they introduced the model, which comprises Hertz–Mindlin contact model and freeze bond model with linear cohesion and softening. Finally, the authors presented the numerical results obtained using EDEM is commercial Discrete Element Modeling software (EDEM) and analysed the results.

The Hertz–Mindlin model with cohesive freeze bonds and linear softening is a reasonable model for ice rubble. It is trivial that the ice blocks within the ice ridge are not spherical particles, but according to results, the representation of ice blocks as spheres gave promising results. The simulation results provide information on how the properties of freeze bond affect the results of punch shear test. Thus, the simulation results can be used to approximate the freeze bonds properties within an ice ridge when experimental data are available.

As the exact properties of ice rubble are unknown, more research is required both in experimental and theoretical fields of ice rubble mechanics.

Based on this numerical study, the authors are able to determine the main characteristics of an ice ridge from material parameters of ice and freeze bonds. Furthermore, the authors conclude that the model creates a promising basis for further development in other applications within ice mechanics.

The gas containers of aircraft are made of fabric coated with solutions or varnishes of phenyl resin, commonly known under the Trade Mark “Bakelite.” The varnish is softened with castor oil, tricresyl phosphate, triphenyl phosphate or other suitable softener, and sprayed, painted or calendered on to the fabric. The varnish may be thinned with acetone. The softening and thinning medium may be varied within wide limits. Four different formulae illustrating suitable mixings are given in the Specification.

THIS report covers the second and final portion of an investigation of the cowling and cooling of radial air‐cooled engines on an open cockpit fuselage. The first portion, which dealt with the cowling of a “Whirlwind” engine in a cabin fuselage was summarised at length in the last issue of AIRCRAFT ENGINEERING.

The purpose of this paper is to develop a process chain for design and manufacture of endplates of intervertebral disc implants, with specific emphasis on designing footprint profiles and matching endplate geometry.

Existing techniques for acquiring patient‐specific information from CT scan data was and a user‐friendly software solution was developed to facilitate pre‐surgical planning and semi‐automated design. The steps in the process chain were validated experimentally by manufacturing Ti6Al4 V endplates by means of Direct Metal Laser Sintering to match vertebrae of a cadaver and were tested for accuracy of the implant‐to‐bone fitment.

Intervertebral disc endplates were successfully designed and rapid manufactured using a biocompatible material. Accuracy within 0.37 mm was achieved. User‐friendly, semi‐automated design software offers an opportunity for surgeons to become more easily involved in the design process and speeds up the process to more accurately develop a custom‐made implant.

This research is limited to the design and manufacture of the bone‐implant contacting interface. Other design features, such as keels which are commonly used for implant fixation as well as the functionality of the implant joint mechanics were not considered as there may be several feasible design alternatives.

This research may change the way that current intervertebral disc implants are designed and manufactured.

Apart from other areas of application (cranial, maxillofacial, hip, knee, foot) and recent research on customized disc nucleus replacement, very little work has been done to develop patient‐specific implants for the spine. This research was conducted to contribute and provide much needed progress in this area of application.

A description of the design philosophy pursued for the principal load carrying structures, materials employed and details of the structural test programme. THE structural concept of the F.28 Fellowship is based on principles that have proven their soundness during the extensive static and fatigue testing as well as during about 2½ million world‐wide operational flying hours of the F.27 Friendship.

This paper presents an overview of the articles used in this edition of Advances in Health Care Management. The beginning of the article gives the reader a history of bioterrorist activity within the United States, and how these events have led to current situations. It also provides a model for health care leaders to follow when looking at a bioterrorist attack. The model includes descriptions of how the articles within this book relate to an overall bioterrorist formula. Through this, the reader shall be able to deduce which individual article fits into the vastness of healthcare research pertaining to bioterrorism.

The cathodic protection of ships against corrosion has a long history, for it was first applied in 1824 by Sir Humphry Davy for the protection of the copper sheathed hulls of British warships. Here the author describes the modern art of cathodic protection which can be used at every stage of a ship's life from the fitting‐out period onwards. Besides its main use for the protection of hulls, the method is applicable to propellors, stern gear, cargo compartments, etc., and it can result in very considerable savings in repair costs. The author also discusses the cathodic protection of other marine structures such as floating docks, mooring buoys, etc.

THE airship Hindenburg was destroyed by fire at 6.25 p.m., E.S.T.,1 May 6, 1937, at the naval air station, Lakehurst, N.J. The airship was completing its first scheduled demonstration flight for the 1937 season, between Frankfurt, Germany, and Lakehurst. It had departed from Frankfurt about 8.15 p.m., G.M.T., Monday, May 3, and was due at Lakehurst on the morning of Thursday, May 6. It was due out of Lakehurst at 10 p.m., E.S.T. that night. Because of unfavourable winds encountered en route, its arrival at Lakehurst was deferred until 6 p.m., Thursday evening, and departure was to be postponed until midnight or later in order to reservice and prepare for the return voyage.

SINCE the Report of the investigations into the causes and circumstances of the accident to R.101 do not bring out any noticeably new facts, and in general can be said to bear out the statements made and conclusions arrived at m the article on the accident published in AIRCRAFT ENGINEERING, Vol. II, November, 1930, pp. 278–280, it does not appear necessary to publish here any extended summary of it, particularly as this has been amply done elsewhere. It may, however, be well to give the authenticated figures of the weight and lift of the airship, as given in the Report, as they differ somewhat from the estimates published in the article already referred to. As originally designed, the hull was 732 feet long, with a maximum diameter of 132 feet, the total gasbag capacity being 4,998,500 cubic feet, giving a gross lift of 148 6 tons. The fixed weights amounted to 113·6 tons, leaving a useful lift of 35 tons, instead of the 60 tons for which the specification had called. To remedy this deficiency the servo control and certain fittings were removed, giving a gain of 2·3 tons, and the gasbag wiring was let out, giving a further gain of 3·4 tons; the total gain from these modifications being 5·7 tons. In addition to these alterations, an extra bay (8a) containing a gasbag with a opacity of 510,300 cubic feet was inserted, which resulted in a further net gain of 8·6 tons. After these modifications the length of the hull was 777 feet, the maximum diameter remaining the same as before, and the total gasbag capacity had been increased to 5,508,800 cubic feet, giving a gross lift of 167·2 tons. The fixed weights now amounted to 117·9 tons, leaving a useful lift of 49·3 tons.