Object-oriented Configuration Research Articles

HistFitter software framework for statistical data analysis

We present a software framework for statistical data analysis, called HistFitter, that has been used extensively by the ATLAS Collaboration to analyze big datasets originating from proton-proton collisions at the Large Hadron Collider at CERN. Since 2012 HistFitter has been the standard statistical tool in searches for supersymmetric particles performed by ATLAS. HistFitter is a programmable and flexible framework to build, book-keep, fit, interpret and present results of data models of nearly arbitrary complexity. Starting from an object-oriented configuration, defined by users, the framework builds probability density functions that are automatically fitted to data and interpreted with statistical tests. A key innovation of HistFitter is its design, which is rooted in core analysis strategies of particle physics. The concepts of control, signal and validation regions are woven into its very fabric. These are progressively treated with statistically rigorous built-in methods. Being capable of working with multiple data models at once, HistFitter introduces an additional level of abstraction that allows for easy bookkeeping, manipulation and testing of large collections of signal hypotheses. Finally, HistFitter provides a collection of tools to present results with publication-quality style through a simple command-line interface.

A hybrid approach for modeling and solving product configuration problems

Within the context of build-to-order or assembly-to-order production strategy, an end product satisfying the requirements of a customer often comprises various components or parts that may be provided by the partnering suppliers. More probably, there exist a numerous number of alternative components or parts to be chosen when an end product is configured. Meanwhile, structures and constraints within the configurable product must be observed. To represent structures of products and constraints, object-oriented modeling method is employed to enable the share and reuse of configuration knowledge. To derive optimal configuration, product configuration problem with object-oriented configuration knowledge is formalized as a mixed-integer programming problem. The algorithm for product configuration optimization is implemented using Java CPLEX. Experiments are conducted to demonstrate and compare the performance of the algorithm. The results show that the computational time is reasonable and acceptable for medium-sized configuration problems.

An object-oriented configuration design method for paper feeding mechanisms

As printing machines attain higher operating speeds, paper feeding mechanisms are more prone to problems such as vibration, noise, and paper jams. To design reliable paper feeding mechanisms, designers first use heuristic knowledge to decide the basic specifications of the printer according to the user's requirements. In the preliminary design stage, the design process is represented hierarchically and the characteristics of each part are determined. Conceptually, the process is analogous to the methodology used in configuration design. In this research, the design process has been analyzed systematically by the OMT (object modeling technique) method, which integrates the object, functional, and dynamic models. The physical parts of the paper feeding mechanism are represented as objects, and the design knowledge and design constraints are represented by rules and methods. A commercial expert system shell, Nexpert Object, is adapted for the implementation. The inferred results are converted to create the BOM (bill of materials) data and are saved in a database for the detailed design and production stage.

A logical theory of concurrent objects

A new theory of concurrent objects is presented. The theory has the important advantage of being based directly on a logic called rewriting logic in which concurrent object-oriented computation exactly corresponds to logical deduction. This deduction is performed by concurrent rewriting modulo structural axioms of associativity, commutativity and identity that capture abstractly the essential aspects of communication in a distributed object-oriented configuration made up of concurrent objects and messages. Thanks to this axiomatization, it becomes possible to study the behavior of concurrent objects by formal methods in a logic intrinsic to their computation. The relationship with Actors and with other models of concurrent computation is also discussed. A direct fruit of this theory is a new language, called Maude, to program concurrent object-oriented modules in an entirely declarative way using rewriting logic; modules written in this language are used to illustrate the main ideas with examples. Maude contains OBJ3 as a functional sublanguage and provides a simple and semantically rigorous integration of functional programming and concurrent object-oriented programming.