The invention relates to data exchange systems. More particularly, the invention provides a system for exchanging data between application modules, including uncertainty distribution information.
Integration of multiple processes or systems is a necessity in many industries. Transfer of information between distinct processes or systems is often accomplished by manual means. For example, output information from a first system may be typed in as input for a second system. Even when the output information from the first system is available in electronic form, it often requires re-formatting in order to be used as input for the second system. This results in tremendous inefficiencies, particularly when the systems or processes must be repeated, as may be the case in, for example, feedback systems.
An integrated system may include systems or processes using a variety of commercially available packages. Such packages often are not adaptable to interact with each other. For example, in a system for simulating a chemical plant, the output from a reactor model using, for example, Chemkin may not be acceptable as input by a CFD module using, for example, STAR CD.
Further challenges are posed by the need to incorporate uncertainty information, as may be required for certain input or output parameters. For example, an input parameter may have a nominal value with an associated probability density distribution which results in a probability distribution of one or more output parameters. This output probability distribution may be required as an input for yet another process or system, thus requiring efficient transfer not only of nominal parameter values, but also of their probability density distribution.
The Chemistry WebBook database maintained by National Institute of Standards and Technology (NIST) provides maximum and minimum values and/or a range of values as uncertainties for various parameters in a chemical reaction. However, such a system only provides either a uniform distribution or a predetermined distribution of the probability function.
The disclosed systems and methods are directed to exchange of uncertainty information between interacting modules. Variances in the outputs of one module may be required as uncertainties in the inputs of another module. The disclosed systems and methods allow for simple and efficient communication of the uncertainty information between any modules.
In one aspect of the invention, a system of integrated modules includes one or more application modules adapted to receive inputs and/or generate outputs. The inputs and outputs include uncertainty distribution information.
An application module may be any component of a system of processes, mechanisms, or algorithms. An application module may include a process, a sub-process, a mechanism, an algorithm step, a calculation, or a software package simulation. Further, an application module may be a part of or one or more processes, sub-processes, mechanisms, algorithm steps, calculations, simulations or other components.
Inputs are parameters that are used by one or more modules. Inputs may include, for example, internal or external parameters that may be preset, provided by a user, or provided by another module.
Outputs are parameters that are generated by one or more modules. Outputs may include parameters that are generated by a module in response to one or more inputs.
Uncertainties may be uncontrollable variations in the inputs that may cause variations in the outputs. Uncertainties may be distributed continuously or discretely over a range of values. Uncertainty distribution may be the probability of occurrence of any value of a variable. For example, a Gaussian distribution may indicate the likelihood of occurrence of a variable value between −∞ and +∞.
The system further includes at least one interface module adapted to communicate with one or more application modules. The interface module is adapted to translate uncertainty information from any one of the application modules to a predetermined uniform format and/or to translate uncertainty information from the predetermined uniform format to an application-specific format.
An interface module may be a software package, routine or set of routines. A predetermined format may be a way of presenting data which is readily translated by other application modules. An application-specific format may be a data presentation format that is unique to a particular application module.
In another aspect of the invention, a system of integrated modules includes application means for receiving inputs and/or generating outputs. The inputs and the outputs include uncertainty distribution information.
The application means may be any component of a system of processes, mechanisms, or algorithms and may include a process, a sub-process, a mechanism, an algorithm step, a calculation, or a software package simulation. Further, the application means may be a part of or one or more processes, sub-processes, mechanisms, algorithm steps, calculations, simulations or other components.
The system further includes interface means for communicating with the application means. The interface means is adapted to translate uncertainty information to a predetermined uniform format and/or to translate uncertainty information from the predetermined uniform format to an application-specific format.
In a preferred embodiment, the uncertainty distribution information is indicative of a type of distribution and includes data indicative of uncertainty densities.
A distribution type may be a description of likelihood of possible values of a variable. Possible distribution types may be Gaussian, lognormal and exponential.
In a further preferred embodiment, the uniform format is an extensible markup language (XML) format. The XML format is well known to those skilled in the art. The XML format may include an uncertainty description element and one or more data elements, the data elements being determined according to the description element.
An element is a data component in an XML format. The description element may be associated with a distribution type, and the data elements may be associated with characteristic parameters of the distribution type. Characteristic parameters may be parameters whose values define the likelihood of occurrence of a particular value of a variable based on the type of distribution. For example, a mean value and a standard deviation value may define the likelihood of occurrence of any value of a variable having a Gaussian distribution.
A value of the description element may be one of the set consisting of normal probability density function, exponential probability density function, polynomial chaos expansion, list of points, and histogram.
In a preferred embodiment, the application module may be associated with an input interface module and an output interface module. The input interface module may be adapted to communicate with an output interface module of another application module. The output interface module may be adapted to communicate with an input interface module of another application module
In a preferred embodiment, the system further includes a platform module for controlling communication with the application module through the interface module. The platform module is adapted to control data flow to and from the application modules.
The platform module may include a graphic user interface module for displaying information to a user and receiving inputs from a user. A graphic user interface module may be a software package, a routine or a set of routines adapted to allow communication between a user and a system. The graphic user interface module may display data in graphic form to the user.
The platform module may include an optimization module for optimizing a system uncertainty in response to the application module. The optimization module may be a software package or a routine for either maximizing or minimizing an objective function. The objective function may be any parameter or combination of parameters whose value is desired to be either minimized or maximized. The optimization module may be adapted to iterate to a convergence of a mean value.
In another aspect of the invention, a method for exchanging data includes receiving an output from an application module. The output includes a set of values for an output parameter. The set of values is indicative of a variance in the output parameter.
The set of values may be possible values of an output parameter. The variance may be a distribution of the output parameter caused by an uncertainty in one or more inputs of the application module.
The method further includes selecting a distribution type from a predetermined list of types, the selecting being based on a distribution of the set of values.
A distribution type may be a description of likelihood of possible values of a variable. Possible distribution types may be Gaussian, lognormal and exponential.
The method also includes determining values of one or more characteristic parameters, the characteristic parameters being associated with said selected distribution type.
In a preferred embodiment, the method further includes generating an output set, the output set including the selected distribution type and the values of said characteristic parameters. In a further preferred embodiment, the output set is in an XML format.
In the following, the invention will be explained in further detail with reference to the drawings, in which:
The application module 110 is adapted to receive one or more inputs from, for example, a user, an external source, or a predetermined, internally provided input. The inputs are used by the application module 110 to generate one or more outputs. One or more of the inputs may have an associated uncertainty distribution. For example, an input such as an environment temperature may have an uncontrolled uncertainty which may be defined as a Gaussian distribution or a lognormal distribution. Of course, other distributions are possible.
The application module 110 may be adapted to propagate the uncertainties in the inputs to the outputs of the application module 110. This may be performed in one of many ways, such as a Monte Carlo analysis. In other embodiments of the invention, the propagation of uncertainties may be more efficiently accomplished by first generating a deterministically equivalent model of the application module, as described in U.S. Patent Application, titled “METHOD AND SYSTEM FOR INTEGRATED UNCERTAINTY ANALYSIS,” Attorney Docket No. 037010-0105, filed concurrently herewith and hereby incorporated by reference in its entirety.
The outputs of the application module 110 may, thus, include variances reflecting propagated input uncertainties. In a system of interacting application modules, the uncertainty information in the outputs of the application module 110 may be required as an input for another application module.
The interface module 120 is adapted to receive the outputs of the application module 110 and to generate an output set in a predetermined uniform format adapted to be accessible by other application modules. As described below with reference to
In one embodiment, the interface module 120 may receive raw data relating to variances in the outputs due to the input uncertainties. The interface module 120 may then determine the type of probability density function that best describes the distribution of each output parameter. The determination of the type of function may be accomplished by selecting from a predetermined set of distribution types. For example, a Monte Carlo analysis may yield a distributed set of output parameter values. This set of values may be used by the interface module 120 to determine that the distribution is best described by a normal Gaussian distribution function with a mean and a standard deviation. The Gaussian distribution function may be one among a list of types from which the interface module 120 may select. In addition to Gaussian, the list may include lognormal, polynomial chaos expansion (PCE), set of points, etc. For each distribution type in the list, one or more characteristic parameters, such as mean and standard deviation, may be determined by the interface module 120 to fully define the probability density distribution of the output parameter.
The interface module 120 may then generate an output set, as described below with reference to
Similarly, as illustrated in
In another embodiment, as illustrated in
Referring again to
The optimization/iteration module 440 may be based on any one of several well-known optimization or iteration algorithms. For example, a sequential quadratic programming algorithm may be used.
Similarly, other uncertainty distribution types may be specified for each variable. For example, the uncertainty distribution of a variable having an exponential PDF distribution may be described by providing a mean value. Other distribution types that may be described using this common data architecture may include a polynomial chaos expansion, a list of points, or a histogram. Thus, the uncertainty distribution of each variable, input or output may be associated with the variable itself in, for example, a database.
An embodiment of the invention may be implemented on a processor such as the computer system illustrated in
A hard drive 722 may be provided to store data and instructions in a non-volatile memory, for example. Further, a random access memory 724 is provided to temporarily store instructions for the CPU. The random access memory 724 may be provided with stored instructions by, for example, an executable residing on the hard drive 722 or on an external storage medium such as a floppy disk or a CD-ROM 728. Information on the CD-ROM 728 may be accessed by the CPU 720 via a CD-ROM drive 726. Other drives may be provided to access information from other types of external storage media.
The CPU 720 may receive instructions, commands or data from an external user through input devices such as a keyboard 730 and a mouse 740. The CPU 720 may display status, results or other information to the user on a monitor 750.
While particular embodiments of the present invention have been disclosed, it is to be understood that various different modifications and combinations are possible and are contemplated within the true spirit and scope of the appended claims. There is no intention, therefore, of limitations to the exact abstract or disclosure herein presented.