Special Coverage

Home

Software Assists in Extensive Environmental Auditing

The Base Environmental Management System (BEMS) is a Web-based application program for managing and tracking audits by the Environmental Office of Stennis Space Center in conformity with standard 14001 of the International Organization for Standardization (ISO 14001). (This standard specifies requirements for an environmental- management system.) BEMS saves time by partly automating what were previously manual processes for creating audit checklists; recording and tracking audit results; issuing, tracking, and implementing corrective-action requests (CARs); tracking continuous improvements (CIs); and tracking audit results and statistics. BEMS consists of an administration module and an auditor module. As its name suggests, the administration module is used to administer the audit. It helps administrators to edit the list of audit questions; edit the list of audit locations; assign mandatory questions to locations; track, approve, and edit CARs; and edit completed audits. The auditor module is used by auditors to perform audits and record audit results: it helps the auditors to create audit checklists, complete audits, view completed audits, create CARs, record and acknowledge CIs, and generate reports from audit results.

Posted in: Briefs

Read More >>

Software Supports Distributed Operations via the Internet

Multi-mission Encrypted Communication System (MECS) is a computer program that enables authorized, geographically dispersed users to gain secure access to a common set of data files via the Internet. MECS is compatible with legacy application programs and a variety of operating systems. The MECS architecture is centered around maintaining consistent replicas of data files cached on remote computers. MECS monitors these files and, whenever one is changed, the changed file is committed to a master database as soon as network connectivity makes it possible to do so. MECS provides subscriptions for remote users to automatically receive new data as they are generated. Remote users can be producers as well as consumers of data. Whereas a prior program that provides some of the same services treats disconnection of a user from the network of users as an error from which recovery must be effected, MECS treats disconnection as a nominal state of the network: This leads to a different design that is more efficient for serving many users, each of whom typically connects and disconnects frequently and wants only a small fraction of the data at any given time.

Posted in: Briefs, TSP

Read More >>

Software Estimates Costs of Testing Rocket Engines

Simulation-Based Cost Model (SiCM), a discrete event simulation developed in Extend™, simulates pertinent aspects of the testing of rocket propulsion test articles for the purpose of estimating the costs of such testing during time intervals specified by its users. A user enters input data for control of simulations; information on the nature of, and activity in, a given testing project; and information on resources. Simulation objects are created on the basis of this input. Costs of the engineering-design, construction, and testing phases of a given project are estimated from numbers and labor rates of engineers and technicians employed in each phase, the duration of each phase; costs of materials used in each phase; and, for the testing phase, the rate of maintenance of the testing facility. The three main outputs of SiCM are (1) a curve, updated at each iteration of the simulation, that shows overall expenditures vs. time during the interval specified by the user; (2) a histogram of the total costs from all iterations of the simulation; and (3) table displaying means and variances of cumulative costs for each phase from all iterations. Other outputs include spending curves for each phase.

Posted in: Briefs

Read More >>

yourSky: Custom Sky-Image Mosaics via the Internet

is a computer program that supplies custom astronomical image mosaics of sky regions specified by requesters using client computers connected to the Internet. [yourSky is an upgraded version of the software reported in "Software for Generating Mosaics of Astronomical Images" (NPO-21121), NASA Tech Briefs, Vol. 25, No. 4 (April 2001), page 16a.] A requester no longer has to engage in the tedious process of determining what subset of images is needed, nor even to know how the images are indexed in image archives. Instead, in response to a requester's specification of the size and location of the sky area, (and optionally of the desired set and type of data, resolution, coordinate system, projection, and image format), yourSky automatically retrieves the component image data from archives totaling tens of terabytes stored on computer tape and disk drives at multiple sites and assembles the component images into a mosaic image by use of a high-performance parallel code. yourSky runs on the server computer where the mosaics are assembled. Because yourSky includes a Web-interface component, no special client software is needed: ordinary Web-browser software is sufficient.

Posted in: Briefs, TSP

Read More >>

Lightweight Mirrors for Orbiting Earth-Observing Instruments

A report discusses selected aspects of a continuing program to develop thermally stable, lightweight mirrors for planned Earth-observing spaceborne instruments. These mirrors are required to retain precise concave or convex surface figures required for diffraction-limited optical performance, even in the presence of transient, asymmetric thermal loads, which include solar heating and radiational cooling. In the first phase of the program, preliminary analyses were performed to select one of three types of mirror structures: one made of SiC, one made of Be, and a hybrid comprising a lightweight composite-material substructure supporting a glass face sheet that would be a substrate for the required precise optical surface. The hybrid structure was selected for further development because it would offer a combination of high stiffness and low mass and because, relative to the Be and SiC structures, (1) the coefficients of thermal expansion of its constituent materials and the resulting wavefront error would be smaller, and (2) it could be fabricated at lower cost. A prototype hybrid structure with an aperture diameter of 0.3 m was fabricated. Planned efforts in the next phase of the program include optical polishing of the glass face sheet and testing.

Posted in: Briefs, TSP

Read More >>

Ultrahigh-Vacuum Arc-Jet Source of Nitrogen for Epitaxy

Electron-excitation and translational energies can be selected. An arc-jet source of chemically active nitrogen atoms has been developed for use in molecular-beam epitaxy (MBE) to grow such III-V semiconductors as nitrides of gallium, aluminum, and indium. This apparatus utilizes a confined arc to thermally excite N2 and to dissociate N2 into N atoms. This apparatus is compatible with other, ultrahigh-vacuum MBE equipment commonly used in growing such materials.

Posted in: Briefs, TSP

Read More >>

Scanning Thermography

Large objects can be scanned fairly quickly. Scanning thermography is a noncontact, nondestructive technique that makes it possible to find defects hidden inside structural components in a variety of settings. Scanning thermography can be used to perform inspections of objects that may have large areas and a variety of shapes and that are found in a variety of settings that include, but are not limited to, production lines, industrial tanks and pipes, aircraft, power plants, and bridges. Scanning thermography is applicable to diverse structural materials, including metals, plastics, laminated polymer-matrix composites, and bonded aluminum composites, to name a few. Defects that can be detected by scanning thermography include cracks, disbonds (delaminations), corrosion, and wear.

Posted in: Briefs

Read More >>