Computer-derived management information in a special library

Not the least of the benefits of automating libraries and information centers is the enhanced ability to monitor processes and services, to collect, structure, analyze, and report critical or useful data hitherto largely unavailable or excessively difficult and costly to obtain. Good management of information requires good management information information that is as cogent, correct, current, clear, concise, and complete as cost effectiveness and enlightened decision-making demand. Computeraided information systems offer not only opportunities to gain new insights into the services they support; they challenge the systems designer to build in the feedback necessary to control and improve the systems themselves. The focus of this paper is computer-supplied management information in the special library environment. The particular context is that of an extensively computerized, corporate library network in a large research and development organization Bell Laboratories.published or submitted for publicatio

Graphite as a structural material in conditions of high thermal flux: a survey of existing knowledge and an assessment of current research and development

The state of fundamental knowledge on the subject of graphite and the graphitisation process is reviewed. The principle methods of manufacture may be considered to include (1) conventional graphitisation of a coke filler-binder mix, (2) the compaction at high pressure and temperatures of natural or artificial graphite particles without a binder, (3) pyrolytic graphites derived from gaseous deposition, and (4) conventional graphites impregnated by liquid or gas and re-graphitised. The present state of development of these processes is examined. The erosion of graphite by high velocity gases at high temperatures is due primarily to oxidation effects which occur preferentially at crystallite boundaries. Coatings of carbides and nitrides improve the resistance at temperatures below about 1700 degrees C, but above this, pyrolytic coatings are more successful. The addition of vapourising compounds, iodides and fluorides, or the addition of carbides and nitrides to the graphite mix, are both beneficial, but of little value at very high temperatures. The development of new graphites, either the impregnated type, or those produced by pressure baking, may offer a margin of improvement, as the best surface structure at temperatures of 3000 degrees C and above appears to be simply graphite. Additions may do little to improve the mechanism of erosion, but they may usefully lower the surface temperature. Considerations relating to thermal shock, creep and fabrication are surveyed. Some of the conclusions are: that graphite is of singular importance to high temperature technology; that commercial issues cannot be allowed to impede vigorous development towards more resistant forms; that much is to be gained by viewing graphite from a metals standpoint; that the fundamental theory of the basic crystal mechanics is undeveloped; that the present wide variability in properties should not be regarded overseriously; that non-destructive assessment by damping measurements needs development, that coatings and impregnants are of high priority, and that, of all factors, oxidation is the most serious limitation to use at the present time

The ALEPH Search for the Standard Model Higgs Boson

A search has been performed for the Standard Model Higgs boson in the data collected with the ALEPH detector in 2000. An excess of 3 sigma above the background expectation is found. The observed excess is consistent with the production of the Higgs boson with a mass close to 114 GeV/c2.Comment: 5 pages, 5 figure

Oscillations of atomic fermions in a one dimensional optical lattice

A semiclassical model is used to investigate oscillations of atomic fermions in a combined magnetic trap and one dimensional optical lattice potential following axial displacement of the trap. The oscillations are shown to have a characteristic small amplitude, damped behavior in the collisionless regime. The presence of a separatrix in the semiclassical Brillouin zone phase space is predicted and shown to produce a strongly asymmetric phase space distribution function.Comment: 6 pages, 6 figure

Temperature effects on material characteristics

Some of the physical properties of the main elements of interest in high temperature technology are reviewed. Some general trends emerge when these properties are viewed as a function of melting point, but there are a few notable exceptions. Titanium, zirconium, niobium and tantalum all have disappointingly low moduli; chromium is excellent in many ways, but has a limited ductility at lower temperatures; molybdenum oxidises catastrophically above about 700° C, and niobium suffers from severe oxygen embrittlement. Beryllium and carbon (in the graphitic form) both stand out as exceptional materials, both have very low densities, beryllium a very high modulus but an unfortunately low ductility, while graphite has a relatively low strength at the lower temperatures, although at temperatures of 2000° C and above it emerges as a quite exceptional (and probably as the ultimate) high temperature material. Some of the fundamental factors involved in high temperature material development are examined, in the light, particularly, of past progress with the nickel alloys. If a similar progress can be achieved with other base elements then a considerable margin still remains to be exploited. Protection from oxidation at high temperatures is evidently a factor of major concern, not only with metals, but with graphite also. Successful coatings are therefore of high importance and the questions they raise, such as bonding, differential thermal expansion, and so on, represent aspects of an even wider class covered by the term “composite structures". Such structures appear to offer the only serious solution to many high temperature requirements, and their design, construction and utilization has created a whole series of new exercises in materials assessment. Matters have become so complex, that a very radical and fundamental reassessment is required if we are to change, in any very significant way, the wasteful and ad hoc methods which characterise so much of present-day materials engineering