Factor
(n) A dimensionless quantity which, when multiplied by to some other quantity, accommodates uncertainties in knowing the value of that other quantity. Contrast with margin. (v) To decompose a parameter into subordinate parameters by means of some defining relationship (e.g., an equation).
Feature
A discernible element of form, fit, or function in the dingus. The best features are those dreamed up by the designers that can make our designs better1 than those of our competitors, even if the customers didn’t think of asking for them yet. Contrast that outcome with the idea of Bill It As A Feature, which entails risk... read more
Federal Acquisition Regulations (FAR)
The body of regulations governing the procurement of materiel and services by the Federal Government. See http://www.acquisition.gov/far. Not to be confused with FAR.
Federal Aviation Administration (FAA)
The national aviation authority for the USA; the regulatory customer for commercial aircraft.
Federal Aviation Regulations (FAR)
The body of regulations governing the certification and use of aircraft in the USA. See http://www.faa.gov/regulations_policies/faa_regulations. See also FAA. Not to be confused with FAR.
Field Joints
The issue of “field conditions” is significant because the CBM is Primary Structure with respect to containing pressure in a high vacuum environment. Like a “factory joint”, the elastomeric seals of a “field joint” are susceptible to issues of long term compression set and to local concentrations of stress. Unlike a factory joint, a field... read more
Figure of Merit
A Figure of Merit (FoM) is a calculated parameter used to characterize some aspect of optimization or (less often) aggregation with respect to the dingus. This notion is distinct from direct characterization of the dingus itself. FoM can be hideously complicated, which is usually a good sign that things might have become overly confuscated. See, for... read more
Firmware
Practical, but unofficial definition: data and instructions compiled, or capable of being compiled, into machine readable form such that it can execute without transfer (“loading”) from its on-device storage memory. (i.e., it executes in the same memory address space where it is stored). A computer’s BIOS is a good example of firmware.
Fit
The precise details of how two or more items interface (whether functionally or physically), inclusive of tolerances. This term is most often used in the static or quasi-static sense, but can be used in a dynamic context. Compare to form and function. See also Form, Fit, and Function.
Flight Readiness Review (FRR)
A formal review of a launch system to determine whether the End User (usually NASA) is ready to begin final preparations for launch. All aspects of the system are in-scope to the process.
Form
(1) In legacy hardware usage: the abstract shape of an item absent details of size. “Aspect ratio” is an expression of form, as is “circle”, or “ellipse”. (2) In more recent usage: the features of an item, absent quantification and (sometimes) even parameterization. For example, logical partitioning of algorithm1. Caution is advised in the usage of... read more
Form, Fit, and Function
The three things which, when thoroughly revealed, completely describe a part 1. Note that things like manufacturing processes might not be included in this usage unless they are intrinsic to the End User‘s ability (or willingness) to rely on one or more of these three concepts2. See also, form, fit, and function. Footnotes Which may, or may... read more
Four Rules for Engineers
Don’t lie1. Don’t cheat. Don’t steal. When somebody gives you something stupid to do, get it off your desk as fast as possible. Guidance with respect to Rule 4: Rule 4 does not necessarily mean you have to do the stupid thing. It could mean talking the action owner back onto this planet, or it... read more
Full Scale Engineering Development (FSED)
A contractual phase in which a system is designed and qualified (“developed”), with the full rate production line(s) being readied as part of the same contract. Contrast with CRAD, which typically does not have the same emphasis on (at least eventual) full rate production. FCA and at least one PCA are typically included in FSED.
Function
1) In mathematics: a relation between a set of inputs and outputs. 2) In System Engineering: A means to impose a particular system state1. To be useful as an Engineering abstraction, a function has to relate to the way the system’s state variables are changed (or, held constant; see also Performance Requirement). The state... read more
Functional Analysis
1. In mathematics: the abstract study of characteristic properties possessed by different classes of mathematical functions. 2. In Systems Engineering a. The prescriptive process of decomposing functions into smaller functions. b. The descriptive process of identifying functions performed by some existing system or item. 2.b is the original sense of the term in System Engineering, used... read more
Functional Baseline
The complete set of functions (and their associated measures) necessary for a system to meet its intended Operational Requirements in the context of a preliminary design, formally designated as the initial technical baseline for subsequent development. In this context, “complete” is used prescriptively rather than restrictively. When complete, a hardware design will always have functions... read more
Functional Configuration Audit (FCA)
One of the most unfortunate misnomers in the System Engineering lexicon, FCA is the audit that closes the design part of development. The name traces its origin back to the concept of a Functionally Allocated Baseline.
Functional Decomposition
A decomposition process executed in the functional domain. The completeness criterion is to show that the sub-functions (“child functions”) effect the state change (or maintenance) that spans the function being decomposed (“parent function”). Re-parameterization of the system’s state vector is an acceptable means of demonstrating completeness, provided that the re-parameterization is at-least-locally1 deterministic2 in both... read more
Functionally Allocated Baseline
A follow-on to the Functional Baseline, where Its functions have been formally assigned (allocated) in the form of Performance Requirements to subordinate Configuration Items as identified during the Preliminary Design process; All other types of requirements have been allocated to the subordinate CI’s using the hierarchy established by the functional decomposition. If necessary in order... read more
Game Theory
Game Theory is a mathematical construct that attempts to model how rational interactions (e.g., competition, cooperation) should proceed. Use of the word “game” does not suggest that the context is frivolous; only that the people (and organizations) involved can have differing information and ignorance, goals and aversions, advantages and disadvantages, rewards and penalties influencing their courses of action.... read more
General Specification
In the MIL-STD-490 context, a type of specification containing the technical requirements generically applicable to more than one CI or class of CI, avoiding the repetition of requirements common to more than one detail specification or set of addendum specifications. These specifications were an early (and effective) implementation of concepts that Object Oriented software engineers... read more
Government Furnished Equipment (GFE)
Designs and/or articles that are provided by the Government acquisition customer as part of the system. The use of GFE can significantly complicate development, but sometimes there are no good alternatives to the practice. When GFE is itself not yet complete, it can take of the form of a directed design solution. The notion that... read more
Granddaddy
A thing taken as authoritative in its own right, needing neither further justification nor rationale.
Graph Theory
A mathematical framework for characterizing properties of how dots are connected. Since connecting the dots is a primary focus of System Integration, such a framework can come in pretty handy when you’re trying to understand the implications of dot-to-dot connectedness. If this sounds a bit too esoteric, consider the concept of a Specification Tree and... read more
Handbook
In the system of DoD development documentation, a publication of guidance. The DoD Handbook cannot (in theory) be referenced by contractual document as “required”, but I haven’t noticed that fact actually stops anybody from trying.
Hardhead
A legacy term for Engineers who keep a close eye on reality, and have the backbone to stick with it against all comers…especially those who would reduce the cost and schedule of things they don’t understand.
Hardware
Any artifact 1 comprised of atoms. Just for the sake of starting an endless argument, note that “software“2 and “procedures” are not made up of matter, but the means of their publication can be3. Footnotes Meaning “made by humans”.[↩] Which, in this situation, includes firmware,[↩] aaaaaaand, discuss![↩]
Hardware Authorization Document (HAD)
In the legacy, the HAD stipulated all of the uses to which full-certification-data (e.g., part-marked as if flight hardware) hardware could be applied, authoritatively originating all effectivities for a given program. It was the ultimate source for such data on the application block of the identifying drawings. Modern practices extend this concept to software (a “Software/Hardware... read more