Ceiling-Floor Partition Separation: What Is It and Why Is It Occurring?

This publication is intended to increase the understanding of cracking or separation of finish materials occasionally found in light-frame wood construction. In many cases, the problem is caused by shrinking or swelling of the wood framing members due to changes in moisture content. Although unsightly, these cracks and separations are basically cosmetic and pose no structural problems. It is important to be able to differentiate between movement caused by the instability of wood and that caused by foundation movement or structural failure, which can cause major problems

Computer Applications To Book Catalogs And Library Systems

Librarians must look to the future information needs of a country expanding in population, technology and educational requirements. The "information explosion" is placing an additional strain on existing methods of providing information rapidly and economically. A library seeking to develop a modern information retrieval program has many existing services from which to choose. The problem is to define the program that will best serve the present library users and leave room for flexible action in the future, and then to pick a combination of services that best match these objectives. Documentation Incorporated (Doc Inc) of Bethesda, Maryland, was founded in 1952 by the late Dr. Mortimer Taube, and has been engaged in developing modern information retrieval systems for government and industry. A key concept that is now emerging is the development of mechanized or computerized data banks. This data bank concept is a plan for organizing a single set of data for producing many products. The traditional library card catalog or data bank, long the key to finding materials in the nation's libraries, today is getting competition from book catalogs. Using data bank techniques to keep a library catalog updated, Doc Inc computer systems generate printouts of the catalog which are used to produce bound books for distribution to library users. In effect, the book catalogs are carrying the traditional card catalog, literally, into the homes and offices of users instead of requiring them to trek to the library to find out if the information they want is available. The computer is used to produce several indexes (such as subject, author, and title) in various formats from a single file of data and is particularly effective if the catalog data bank is standardized.published or submitted for publicatio

Weight and power savings shaft encoder interfacing techniques for aerospace applications

Many aerospace applications for shaft angle digitizers such as optical shaft encoders require special features that are not usually required on commercial products. Among the most important user considerations are the lowest possible weight and power consumption. A variety of mechanical and electrical interface techniques that have large potential weight and power savings are described. The principles to be presented apply to a wide variety of encoders, ranging from 16 to 22 bit resolution and with diameters from 152 to 380 mm (6 to 15 in.)

Large craters on the meteoroid and space debris impact experiment

Examination of 29.37 sq m of thick aluminum plates from the LDEF, which were exposed to the meteoroid and man-made orbital debris environments for 5.8 years, revealed 606 craters that were 0.5 mm in diameter or larger. Most were nearly hemispherical. There was a large variation in the number density of craters around the three axis gravity gradient stabilized spacecraft. A new model of the near-Earth meteoroid environment gives good agreement with the crater fluxes measured on the fourteen faces of the LDEF. The man-made orbital debris model of Kessler, which predicts that 16 pct. of the craters would be caused by man-made debris, is plausible. No chemical analyses of impactor residue that will distinguish between meteoroids and man-made debris is yet available

A Method for the Perceptual Optimization of Complex Visualizations

A common problem in visualization applications is the display of one surface overlying another. Unfortunately, it is extremely difficult to do this clearly and effectively. Stereoscopic viewing can help, but in order for us to be able to see both surfaces simultaneously, they must be textured, and the top surface must be made partially transparent. There is also abundant evidence that all textures are not equal in helping to reveal surface shape, but there are no general guidelines describing the best set of textures to be used in this way. What makes the problem difficult to perceptually optimize is that there are a great many variables involved. Both foreground and background textures must be specified in terms of their component colors, texture element shapes, distributions, and sizes. Also to be specified is the degree of transparency for the foreground texture components. Here we report on a novel approach to creating perceptually optimal solutions to complex visualization problems and we apply it to the overlapping surface problem as a test case. Our approach is a three-stage process. In the first stage we create a parameterized method for specifying a foreground and background pair of textures. In the second stage a genetic algorithm is applied to a population of texture pairs using subject judgments as a selection criterion. Over many trials effective texture pairs evolve. The third stage involves characterizing and generalizing the examples of effective textures. We detail this process and present some early results