Civil Rights
Movements, leaders, victories and the continuing fight for equality.
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Explore the people, places, events, achievements, struggles and stories that shaped our journey.
Movements, leaders, victories and the continuing fight for equality.
Innovation, patents, science, technology and world-changing contributions.
Pioneers, champions, Negro Leagues, records, activism and excellence.
Meet the people whose lives, choices and achievements shaped the journey.
Black towns, communities, institutions and places where history happened.
Moments that changed communities, movements, institutions and the nation.
In August 1908, a white mob attacked Springfield, Illinois’s Black community, destroying homes and businesses and lynching two Black men. National outrage over the violence helped spur the movement that created the NAACP the following year.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
| Hierarchical Data Format | |
|---|---|
 | |
| Filename extension | .hdf, .h4, .hdf4, .he2, .h5, .hdf5, .he5 |
| Internet media type | HDF4: application/vnd.hdfgroup.hdf4[1]HDF5: application/vnd.hdfgroup.hdf5[2] |
| Magic number | \211HDF\r\n\032\n |
| Developed by | The HDF Group |
| Type of format | Scientific data format |
| Open format? | Yes [citation needed] |
| Website | www |
Hierarchical Data Format (HDF) is a set of file formats (HDF4, HDF5) designed to store and organize large amounts of data. Originally developed at the U.S. National Center for Supercomputing Applications, it is supported by The HDF Group, a non-profit corporation whose mission is to ensure continued development of HDF5 technologies and the continued accessibility of data stored in HDF.
In keeping with this goal, the HDF libraries and associated tools are available under a liberal, BSD-like license for general use. HDF is supported by many commercial and non-commercial software platforms and programming languages. The freely available HDF distribution consists of the library, command-line utilities, test suite source, Java interface, and the Java-based HDF Viewer (HDFView).[3]
The current version, HDF5, differs significantly in design and API from the major legacy version HDF4.
The quest for a portable scientific data format, originally dubbed AEHOO (All Encompassing Hierarchical Object Oriented format) began in 1987 by the Graphics Foundations Task Force (GFTF) at the National Center for Supercomputing Applications (NCSA). NSF grants received in 1990 and 1992 were important to the project. Around this time NASA investigated 15 different file formats for use in the Earth Observing System (EOS) project. After a two-year review process, HDF was selected as the standard data and information system.[4]
HDF4 is the older version of the format, although still actively supported by The HDF Group. It supports a proliferation of different data models, including multidimensional arrays, raster images, and tables. Each defines a specific aggregate data type and provides an API for reading, writing, and organizing the data and metadata. New data models can be added by the HDF developers or users.
HDF is self-describing, allowing an application to interpret the structure and contents of a file with no outside information. One HDF file can hold a mix of related objects which can be accessed as a group or as individual objects. Users can create their own grouping structures called "vgroups."[5]
The HDF4 format has many limitations.[6][7] It lacks a clear object model, which makes continued support and improvement difficult. Supporting many different interface styles (images, tables, arrays) leads to a complex API. Support for metadata depends on which interface is in use; SD (Scientific Dataset) objects support arbitrary named attributes, while other types only support predefined metadata. Perhaps most importantly, the use of 32-bit signed integers for addressing limits HDF4 files to a maximum of 2 GB, which is unacceptable in many modern scientific applications.
The HDF5 format is designed to address some of the limitations of the HDF4 library, and to address current and anticipated requirements of modern systems and applications. In 2002 it won an R&D 100 Award.[8]
HDF5 simplifies the file structure to include only two major types of object:
This results in a truly hierarchical, filesystem-like data format.[clarification needed][citation needed] In fact, resources in an HDF5 file can be accessed using the POSIX-like syntax /path/to/resource. Metadata is stored in the form of user-defined, named attributes attached to groups and datasets. More complex storage APIs representing images and tables can then be built up using datasets, groups and attributes.
In addition to these advances in the file format, HDF5 includes an improved type system, and dataspace objects which represent selections over dataset regions. The API is also object-oriented with respect to datasets, groups, attributes, types, dataspaces and property lists.
The latest version of NetCDF, version 4, is based on HDF5.
Because it uses B-trees to index table objects, HDF5 works well for time series data such as stock price series, network monitoring data, and 3D meteorological data. The bulk of the data goes into straightforward arrays (the table objects) that can be accessed much more quickly than the rows of an SQL database, but B-tree access is available for non-array data. The HDF5 data storage mechanism can be simpler and faster than an SQL star schema.[example needed]
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Criticism of HDF5 follows[according to whom?] from its monolithic[contentious label] design and lengthy specification:[editorializing]
Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
Hierarchical Data Format (HDF) is a set of file formats (HDF4, HDF5) designed to store and organize large amounts of data. Originally developed at the U.S. National Center for Supercomputing Applications, it is supported by The HDF Group, a non-profit corporation whose mission is to ensure continued development of HDF5 technologies and the continued accessibility of data stored in HDF. In keeping with this goal, the HDF libraries and associated tools are available under a liberal, BSD-like license for general use. HDF is supported by many commercial and non-commercial software platforms and programming languages. The freely available HDF distribution consists of the library, command-line utilities, test suite source, Java interface, and the Java-based HDF Viewer (HDFView). The current version, HDF5, differs significantly in design and API from the major legacy version HDF4.
Veusz is a scientific plotting package. Veusz is a Qt application written in Python, PyQt and NumPy. It is freely available for anyone to distribute under the terms of the GPL. It is designed to produce publication-quality plots. The name should be pronounced as "views". This program produces plots in popular vector image formats, including PDF, PostScript and SVG. It is cross-platform, working under Microsoft Windows, macOS and Unix/Linux. Plots are built up from a set of plotting widgets which can be added to the document and whose properties are edited using a consistent interface. For example, graph widgets can be placed within a grid widget to create an array of graphs. Widgets include X-Y plots, functions, contours, box plots, polar plots, ternary plots, vector plots, data images, labels and a variety of shapes. Datasets can be read using standard formats such as CSV, HDF5 or FITS, or entered, edited or created using functions from existing datasets. Functions can also be fitted to data. Veusz is extensible with Python plugins. Plugins can be added for importing data in other formats, automating operations and creating different kinds of mathematical relationships between datasets. The program also provides a command line and scripting interface (based on Python) to its plotting facilities. The saved file format is a simple Python text script, which makes it easy to create plots from other programs. Veusz was reviewed by Linux Format magazine, saying that "There's plenty of scope for creating colourful, engaging graphics". It was also included in their "Hot Pics" selection on their cover disc. Veusz can also be used as a drawing backend for the SciTools Easyviz package.
GMS (Groundwater Modeling System) is water modeling application for building and simulating groundwater models from Aquaveo. It features 2D and 3D geostatistics, stratigraphic modeling and a unique conceptual model approach. Currently supported models include MODFLOW, MODPATH, MT3DMS, RT3D, FEMWATER, SEEP2D, and UTEXAS. Version 6 introduced the use of XMDF (eXtensible Model Data Format), which is a compatible extension of HDF5. The purpose of this Is to allow internal storage and management of data in a single HDF file, rather than using many flat files.
VSim is a cross-platform computational framework for multi-physics, compatible with Windows, Linux, and macOS. It includes VSimComposer, a GUI for visual setup of simulations, supporting CAD geometry import and direct geometry construction. VSimComposer allows users to execute data analysis scripts and visualize results in one, two, or three dimensions. VSim utilizes the Vorpal computational engine, which has been applied to simulate electromagnetic systems, plasmas, and rarefied as well as dense gases. VSim is used for modeling basic electromagnetic and plasma physics, complex metallic and dielectric shapes, photonics, vacuum electronics including multipactor effects, laser wake-field acceleration, plasma thrusters, and fusion plasma. The Vorpal computational engine is a simulation tool designed to operate across one, two, or three-dimensional spaces. It supports computational modes such as the full electromagnetic mode, where it utilizes the Finite-Difference Time-Domain (FDTD) algorithm, and can also work with electrostatic or magneto-static fields. Particles within Vorpal, whether charged or neutral, can be modeled as a fluid or kinetically using the Particle-in-Cell (PIC) algorithm. The engine ensures these particles interact self-consistently with fields. It can also simulate the interaction of particles and fields with a variety of structures, including conductors, particle absorbers, reflectors, and others, using cut-cell techniques to maintain accuracy. The computational domain in Vorpal offers flexibility with boundary conditions, supporting periodic domains or boundaries that can simulate an infinite space using Perfectly Matched Layers (PML) or other types of outgoing wave boundary conditions. The output data from Vorpal is in the Hierarchical Data Format (HDF5) and is compliant with VizSchema standards, facilitating further analysis and visualization.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Joe Louis.