Retools: Restriping Tools for Lustre

Ames Research Center, Moffett Field, California Modern parallel file systems achieve high performance by distributing (“striping”) the contents of a single file across multiple physical disks to overcome single-disk I/O bandwidth limitations. The striping characteristics of a file determine how many disks it will be striped across and how large each stripe is. These characteristics can only be set at the time a file is created, and cannot be changed later. Standard open-source tools do not typically take striping into account when creating files, so files created by those tools will have their striping characteristics set to the default. The default stripe count is typically set to a small number to favor small files that are more numerous. A small default stripe count, however, penalizes large files that use the default settings, as they will be striped over fewer disks so access to these files will only achieve a fraction of the performance that is possible with a larger stripe count. A large default stripe count, however, causes small files to be striped over too many disks, which increases contention and reduces performance of the file system as a whole.

Posted in: Briefs, Electronics & Computers, Software


Method and Program Code for Improving Machine Efficiency in the Computation of Nearly-Singular Integrals

Lyndon B. Johnson Space Center, Houston, Texas Currently, there is a need for the computational handling of near-singularities that arise in many branches of physics, particularly for handling near-strong singularities. An example of such singularities is presented by the case of gradients of Newton-type potentials and modified Newton-type potentials. Currently, practitioners resort to multiple methods that do not work well, suffer from accuracy issues, or work only for very specialized cases. Accuracy issues provide results that cannot be trusted. Using codes that work only for specialized cases results in either misapplication of the code, and hence reduced accuracy, or failed attempts at a solution or infrequent and expensive code modifications to handle new cases.

Posted in: Briefs, TSP, Electronics & Computers, Software


When Wire Feedthroughs Make Sense

Engineers who work with pressure and vacuum chambers usually reach for off-the-shelf sealed bulkhead connectors when they need to pass power and signal wires through the chamber wall. And while these connectors may seem like the best or only way to breach the chamber walls, they can actually drive cost, impose unnecessary mechanical design constraints and trigger electrical problems. So what’s the alternative? Wire feedthroughs hermetically sealed with epoxy. Learn more in our white paper.

Posted in: White Papers, Aeronautics, Defense, Electronics & Computers


Traceability Best Practices for Systems Engineers

Serious situations: In the middle of a project, your best customer changes a high-level business requirement. How will this change impact the system spec your engineers are working on right now? How will it impact scope for the upcoming release?

Posted in: White Papers, Electronics, Manufacturing & Prototyping, Software


Nonlinear Model Predictive Control

This whitepaper presents an automatic workflow for implementing Model Predictive Control (MPC) controllers. The process uses MapleSim to generate a model of the system, whose dynamic equations are then extracted using Maple. Next, Maple is used to formulate the MPC problem, and generate the solver, which it automatically converts into the C code of the MPC controller. The advantage of using Maple is that the required procedures and their corresponding derivatives are computed and optimized whenever there is a change in the dynamic equations. The use of Maple saves time, removes human error, and produces highly optimized controller code.

Posted in: White Papers, Electronics & Computers, Mechanical Components, Motion Control


Three Phase Active Power Factor Correction in a Single Step

Isolated, Regulated DC Output in One Conversion Reduces Cost, Complexity and Risk Multi-step regulation and isolation of electronic circuits is a complex and costly process for AC to DC conversion in high power applications, demanding close attention to power factor and current distortion, as well as size, weight, efficiency and cost. To solve these challenges for the power conversion engineer, Marotta Controls has developed its new patent-pending 1-STEP AC-DC Conversion™.

Posted in: White Papers, Electronics & Computers



NASA’s Jet Propulsion Laboratory, Pasadena, California Internal electrostatic discharge (IESD) can cause spacecraft failure and anomalies related to the space environment, but it is very hard to predict when IESD might happen. Therefore, assessment of the IESD at a given space environment and a given dielectric geometry is important for spacecraft reliability.

Posted in: Briefs, TSP, Electronics & Computers


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