Software

Quantum Entanglement Molecular Absorption Spectrum Simulator

Quantum Entanglement Molecular Absorption Spectrum Simulator (QE-MASS) is a computer program for simulating twophoton molecular-absorption spectroscopy using quantum-entangled photons. More specifically, QE-MASS simulates the molecular absorption of two quantum-entangled photons generated by the spontaneous parametric down-conversion (SPDC) of a fixedfrequency photon from a laser. The two-photon absorption process is modeled via a combination of rovibrational and electronic single-photon transitions, using a wave-function formalism. A two-photon absorption cross section as a function of the entanglement delay time between the two photons is computed, then subjected to a fast Fourier transform to produce an energy spectrum. The program then detects peaks in the Fourier spectrum and displays the energy levels of very short-lived intermediate quantum states (or virtual states) of the molecule. Such virtual states were only previously accessible using ultra-fast (femtosecond) laser systems. However, with the use of a single-frequency continuous wave laser to produce SPDC photons, and QE-MASS program, these short-lived molecular states can now be studied using much simpler laser systems. QE-MASS can also show the dependence of the Fourier spectrum on the tuning range of the entanglement time of any externally introduced optical-path delay time. QE-MASS can be extended to any molecule for which an appropriate spectroscopic database is available. It is a means of performing an a priori parametric analysis of entangled- photon spectroscopy for development and implementation of emerging quantum- spectroscopic sensing techniques. QE-MASS is currently implemented using the Mathcad® software package.

Posted in: Software, Briefs, TSP

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Updated Computational Model of Cosmic Rays Near Earth

An updated computational model of the galactic-cosmic-ray (GCR) environment in the vicinity of the Earth, Earth’s Moon, and Mars has been developed, and updated software has been developed to implement the updated model. The GCR model and software in their original forms, developed during the early 1990s, were based on balloon and satellite data from 1954 to 1992. This model accounts for solar modulation of the cosmic-ray contribution for each element from hydrogen through iron by computationally propagating the local interplanetary spectrum of each element through the heliosphere. The propagation is effected by solving the Fokker-Planck diffusion, convection, energy-loss boundary-value problem. Since August 1997, the Advanced Composition Explorer NASA satellite has provided new data on GCR energy spectra. These new data were used to update the original model and greatly improve the accuracy of prediction of interplanetary GCR. The updated software was also simplified significantly, relative to the original software. The updated model and software are expected to provide highly accurate GCR-environment data for use by interplanetary- mission planners in planning for protecting astronauts against radiation and ensuring radiation hardness of electronic equipment.

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Program Synthesizes UML Sequence Diagrams

A computer program called “Rational Sequence” generates Universal Modeling Language (UML) sequence diagrams of a target Java program running on a Java virtual machine (JVM). Rational Sequence thereby performs a reverse engineering function that aids in the design documentation of the target Java program. Whereas previously, the construction of sequence diagrams was a tedious manual process, Rational Sequence generates UML sequence diagrams automatically from the running Java code. Moreover, there is no need to insert instrumentation code into the target Java program. Rational Sequence employs the Java Native Interface application programming interface to create a software profiler that plugs into the JVM. Once the user starts the target Java program, Rational Sequence acts as a nonintrusive observer, generating UML diagrams representing the observed activity. Every method call, object instantiation, or thread event of the target Java program is tracked by the profiler. Once the Java program has ended, the profiler generates a UML model that contains packages, classes, and all method calls observed during the execution of the target program. The user can control the way the UML model is generated by specifying packages and/or classes to be included in the diagrams.

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Aspect-Oriented Subprogram Synthesizes UML Sequence Diagrams

The Rational Sequence computer program described in the immediately preceding article includes a subprogram that utilizes the capability for aspect-oriented programming when that capability is present. This subprogram is denoted the Rational Sequence (AspectJ) component because it uses AspectJ, which is an extension of the Java programming language that introduces aspect-oriented programming techniques into the language. The Rational Sequence (AspectJ) component is compiled with a target Java application program on an AspectJ compiler. The user then starts the Java application program. Thereafter, the Rational Sequence (AspectJ) component publishes every visible method call to a Universal Modeling Language (UML) sequence diagram. When the Java application program ends, a sequencer proceeds to generate a UML model that contains packages, classes, and all method calls that occurred during the execution of the program. The user can control the way the UML model is generated by specifying, via the aspect source code, packages and/or classes to be included in the diagrams. Like the rest of Rational Sequence, the AspectJ component complies with the UML specification.

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Simulation of Dropping of Cargo With Parachutes

Decelerator System Simulation (DSS) is a computer program for predicting and analyzing the dynamics of a load of cargo dropped with parachutes from an aircraft. A DSS simulation runs from the first motion in the aircraft until the payload reaches the ground. Intended for use in support of airdrop tests for the X- 38 program, DSS was developed by modifying and augmenting an older program, denoted UD233A, used for simulating the dynamics of a space-shuttle solid rocket booster falling with a parachute. The main effort in converting UD233A into DSS involved development of computational models for simulating the inflation of one or more parachute( s), the dynamics of the payload and the slings connecting the parachute( s) with the payload, and the extraction of the payload and parachutes from the aircraft.

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Software for Alignment of Segments of a Telescope Mirror

The Segment Alignment Maintenance System (SAMS) software is designed to maintain the overall focus and figure of the large segmented primary mirror of the Hobby-Eberly Telescope. This software reads measurements made by sensors attached to the segments of the primary mirror and from these measurements computes optimal control values to send to actuators that move the mirror segments. The software also acts as a logger for the collected data, a server from which the hardware of the control computer can acquire control information and other computers can collect data, and a monitoring and diagnostic system. The software provides a graphical user interface through which human operators can exert control. The software supports four modes of operation: Operate — The server acquires the sensory data and processes them into commands for the actuators. Calibrate — Calibration tests are performed on the edge sensors and the relationships between actuator commands and sensor responses are quantified. Standby — The server is initialized in standby mode, from which it can make the transition to any of the other three modes. Diagnostic — This mode provides access to all sensory data in real time and is intended for use in diagnosis of sensor anomalies.

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DAVE-ML Utility Programs

DAVEtools is a set of Java archives (*.jar files) that embodies tools for manipulating flight-dynamics models that have been encoded in dynamic aerospace vehicle exchange markup language (DAVE-ML). [DAVE-ML is an application program, written in Extensible Markup Language (XML), for encoding complete computational models of the dynamics of aircraft and spacecraft. The goal in the continuing development of DAVE-ML is to expedite the exchange and validation of dynamical models, via the Internet, in a manner that is consistent and is independent of computational-simulation facilities, computing languages, and simulation software.] At present, DAVEtools includes two tools: dave (a basic DAVE-ML parser), which generates a Java-based version of a model encoded in DAVE-ML and dave2sl, which builds on dave to create Simulink® representations of models encoded in DAVE-ML.

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