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Databases
Published in Ian Foster, Rayid Ghani, Ron S. Jarmin, Frauke Kreuter, Julia Lane, Big Data and Social Science, 2020
Care must be taken when loading data in which some values may be missing or blank. The SQL engines represent and refer to a missing or blank value as the built-in constant null. Counterintuitively, when loading data from text files (e.g., CSV), many SQL engines require that missing values be represented explicitly by the term null; if a data value is simply omitted, it may fail to load or be incorrectly represented, e.g., as zero or the empty string (””) instead of null. Thus, for example, the second row in the investigators.csv file of Figure 4.2:
Format Statement
Published in Subrata Ray, Fortran 2018 with Parallel Programming, 2019
An embedded blank with an input field may be treated in two different ways. By default, it is treated as null. However, with an appropriate edit descriptor, it can be interpreted as zero. read 100, ia 100 format (i3)
Media Resource Control Protocol Version 2
Published in Radhika Ranjan Roy, Handbook on Networked Multipoint Multimedia Conferencing and Multistream Immersive Telepresence using SIP, 2020
This header field specifies the terminating DTMF character for DTMF input recognition. The default value is NULL, which is indicated by an empty header field value. This header field MAY occur in RECOGNIZE, SET-PARAMS, or GET-PARAMS.
On defining a model driven architecture for an enterprise e-health system
Published in Enterprise Information Systems, 2018
Blagoj Atanasovski, Milos Bogdanovic, Goran Velinov, Leonid Stoimenov, Aleksandar S. Dimovski, Bojana Koteska, Dragan Jankovic, Irena Skrceska, Margita Kon-Popovska, Boro Jakimovski
An OutputReference describes a projection of the output from an already executed step in the process. It contains a stepId and a propertyName. The stepId identifies one of the steps, and represents an Implementation. The propertyName is one of the properties of the output of the referenced Implementation. The propertyName is nullable, and if it is set to null then the complete output Type is referenced (similar to * in SQL). Let us say that there are two steps in a Process with id’s Step 1 and Step 2. The output of Step 1 is an Object with two properties a and b. Step 1 precedees Step 2 and the Process can transition from Step 1 to Step 2 only if the value stored in the property b of Step 1 is greater than 3. Then the transitions map should contain an instance of an OutgoingTransition class where ”Step” and the implementation of test is .
Logical object structure and system implementation for BIM database in civil infrastructures
Published in Architectural Engineering and Design Management, 2023
Some researchers have noticed these problems and tried to use the database as a storage system for BIM data (called BIM database) (Barzegar, Rajabifard, Kalantari, & Atazadeh, 2021; Park & Cai, 2017). BIM database is used to store and manage BIM data (IFC (buildingSMART, 2021; ISO, 2013)) and realize data sharing (IFD (ISO, 2015) and IDM (ISO, 2010)). Recently most BIM databases have been designed by using the relational model (a database logical model) (ANSI/X3/SPARC, 1975; Tsichritzis & Klug, 1978). However, the relational model is unsuitable for storing and managing BIM data (IFC data). (1) Relational model is designed for table structure data and unsuitable for index structure data (Connolly & Begg, 2015). BIM data is index structure data, such as in IFC data ‘#5=IFCAXIS2PLACEMENT3D (#8, $, $);’, instance #5 index instance #8. The relation model cannot well support the interaction behavior of such kind of data (Silberschatz et al., 2002). (2) The relation matrix of BIM data is sparse. Such as IFC data ‘#5=IFCAXIS2PLACEMENT3D (#8, $, $);’ and ‘#8=IFCDIRECTION ((0., −1., 0.));’, its relation matrix is the sparse matrix . Using the relational model will generate a lot of null keys in the database (i.e. zero in above), which makes the database very unstable and cause a large waste of disk space (Silberschatz et al., 2002). (3) The BIM data types and data relationships are constantly changing for civil infrastructure. For example, a new type of BIM data will be continually added to the database during the modeling process, but the relational model cannot support such interactive behaviors (Connolly & Begg, 2015).
Block-structured compressible Navier–Stokes solution using the OPS high-level abstraction
Published in International Journal of Computational Fluid Dynamics, 2016
Satya P. Jammy, Gihan R. Mudalige, Istvan Z. Reguly, Neil D. Sandham, Mike Giles
To declare data on the blocks, the OPS API (ops_decl_dat) is shown in lines 7 − 10 of Figure 1. Data set declaration in OPS requires information about the block on which it should be declared, the number of dimensions (ndim), the size of the array (size), the number halo points in the positive and negative direction (d_p, d_m), data (dat), as well as its data type and the name (used for debugging). If a NULL pointer is provided as the data, OPS automatically allocates the required amount of memory, depending on the shape of the array and the data-type provided.