503,825 research outputs found
Design requirements and development of an airborne descent path definition algorithm for time navigation
The design requirements for a 4D path definition algorithm are described. These requirements were developed for the NASA ATOPS as an extension of the Local Flow Management/Profile Descent algorithm. They specify the processing flow, functional and data architectures, and system input requirements, and recommended the addition of a broad path revision (reinitialization) function capability. The document also summarizes algorithm design enhancements and the implementation status of the algorithm on an in-house PDP-11/70 computer. Finally, the requirements for the pilot-computer interfaces, the lateral path processor, and guidance and steering function are described
Dynamical Functional Theory for Compressed Sensing
We introduce a theoretical approach for designing generalizations of the
approximate message passing (AMP) algorithm for compressed sensing which are
valid for large observation matrices that are drawn from an invariant random
matrix ensemble. By design, the fixed points of the algorithm obey the
Thouless-Anderson-Palmer (TAP) equations corresponding to the ensemble. Using a
dynamical functional approach we are able to derive an effective stochastic
process for the marginal statistics of a single component of the dynamics. This
allows us to design memory terms in the algorithm in such a way that the
resulting fields become Gaussian random variables allowing for an explicit
analysis. The asymptotic statistics of these fields are consistent with the
replica ansatz of the compressed sensing problem.Comment: 5 pages, accepted for ISIT 201
Space shuttle orbital maneuvering system failure detection and identification software requirements (uncontrolled)
Candidate designs and their software implementation are presented for the Orbital Maneuvering System (OMS) Failure Detection and Identification (FDI) algorithms in the Redundance Management (RM) module of the Space Shuttle Guidance, Navigation, and Control (GN&C) software. The OMS engine FDI algorithm monitors OMS engine thrust performance, and the OMS actuator FDI algorithm monitors OMS gimbal actuator performance. The software functional requirements of the algorithms are described along with the objective of each algorithm. A list of the assumptions which have governed its design, input/output requirements, a functional description of the algorithm (including a functional block diagram), and input interface requirements are given. The HAL (the language of the space shuttle flight computer) software formulation of the algorithms is considered including structured flowcharts of the procedures, estimates of flight computer core storage and CPU time, and processing requirements. A glossary of the symbols used to define the software requirements and formulations is included
A framework for FPGA functional units in high performance computing
FPGAs make it practical to speed up a program by defining
hardware functional units that perform calculations faster than can be achieved in software. Specialised digital circuits avoid the overhead of executing sequences of instructions, and they make available the massive parallelism of the components. The FPGA operates as a coprocessor controlled by a conventional computer. An application that combines software with hardware in
this way needs an interface between a communications port to the processor and the signals connected to the functional units. We present a framework that supports the design of such systems. The framework consists of a generic controller circuit defined in VHDL that can be configured by the user according to the needs of the functional units and the I/O channel. The controller
contains a register file and a pipelined programmable register transfer machine, and it supports the design of both stateless and stateful functional units. Two examples are described: the implementation of a set of basic stateless arithmetic functional units, and the implementation of a stateful algorithm that exploits circuit parallelism
Template Generation - A Graph Profiling Algorithm
The availability of high-level design entry tooling is crucial for the viability of any reconfigurable SoC architecture. This paper presents a template generation algorithm. The objective of template generation step is to extract functional equivalent structures, i.e. templates, from a control data flow graph. By profiling the graph, the algorithm generates all the possible templates and the corresponding matches. Using unique serial numbers and circle numbers, the algorithm can find all distinct templates with multiple outputs. A new type of graph (hydragraph) that can cope with multiple outputs is introduced. The generated templates pepresented by the hydragraph are not limited in shapes, i.e., we can find templates with multiple outputs or multiple sinks
Complete RNA inverse folding: computational design of functional hammerhead ribozymes
Nanotechnology and synthetic biology currently constitute one of the most
innovative, interdisciplinary fields of research, poised to radically transform
society in the 21st century. This paper concerns the synthetic design of
ribonucleic acid molecules, using our recent algorithm, RNAiFold, which can
determine all RNA sequences whose minimum free energy secondary structure is a
user-specified target structure. Using RNAiFold, we design ten cis-cleaving
hammerhead ribozymes, all of which are shown to be functional by a cleavage
assay. We additionally use RNAiFold to design a functional cis-cleaving
hammerhead as a modular unit of a synthetic larger RNA. Analysis of kinetics on
this small set of hammerheads suggests that cleavage rate of computationally
designed ribozymes may be correlated with positional entropy, ensemble defect,
structural flexibility/rigidity and related measures. Artificial ribozymes have
been designed in the past either manually or by SELEX (Systematic Evolution of
Ligands by Exponential Enrichment); however, this appears to be the first
purely computational design and experimental validation of novel functional
ribozymes. RNAiFold is available at
http://bioinformatics.bc.edu/clotelab/RNAiFold/.Comment: 17 pages, 2 tables, 7 figures, final version to appear in Nucleic
Acids Researc
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