Distributed Component Model Research Articles

Linear adjustable inertance tubes for pulse tube cryocoolers

Inertance tube is coupled with Stirling Pulse Tube Cryocooler because its ability of varying the phase angle of pressure and mass flow thereby could potentially increase the performance of the pulse tube cryocooler. The discrepancy between the theoretically designed inertance tube and the installed one causes tons of work for the researchers to figure out the optimum dimensional parameters matching with the pulse tube cryocooler. This paper offers a substituted method to decrease the complications of determining the best match inertance tube for the specific cryocooler. A linear adjustable inertance tube is proposed to fulfill the requirement. The two section distributed component model with step transition and entrance effect resistance is built to anticipate the phase angle performance of the linear adjustable inertance tube. By a 16% length change, 12° phase angle shift is captured both from the model prediction and the experimental measurement.

Performance of an adjustable, threaded inertance tube

The performance of the Stirling type pulse tube cryocooler depends strongly on the design of the inertance tube. The phase angle produced by the inertance tube is very sensitive to its diameter and length. Recent developments are reported here regarding an adjustable inertance device that can be adjusted in real time. The inertance passage is formed by the root of a concentric cylindrical threaded device. The depth of the threads installed on the outer screw varies. In this device, the outer screw can be rotated four and half turns. At the zero turn position the length of the passage is 1.74 m and the hydraulic diameter is 7 mm. By rotating the outer screw, the inner threaded rod engages with additional, larger depth threads. Therefore, at its upper limit of rotation, the inertance passage includes both the original 1.74 m length with 7mm hydraulic diameter plus an additional 1.86 m length with a 10 mm hydraulic diameter. A phase shift change of 24° has been experimentally measured by changing the position of outer screw while operating the device at a frequency of 60 Hz. This phase angle shift is less than the theoretically predicted value due to the presence of a relatively large leak through the thread clearance. Therefore, the distributed component model of the inertance tube was modified to account for the leak path causing the data to agree with the model. Further, the application of vacuum grease to the threads causes the performance of the device to improve substantially.

Large-scale software integration for spoken language and multimodal dialog systems

The development of large-scale dialog systems requires a flexible architecture model and adequate software support to cope with the challenge of presents a general framework for building integrated natural-language and multimodal dialog systems. Our approach relies on a distributed component model that enables flexible re-use and extension of existing software modules and is able to deal with a heterogeneous software environment. A practical result of our research is the development of a sophisticated integration platform, called MULTIPLATFORM, which is based on the proposed framework. This MULTIPLATFORM testbed has been used in various large and mid-size research projects to develop integrated system prototypes.

Component technologies

This one-day tutorial is aimed at software engineering practitioners and researchers, who are familiar with object-oriented analysis, design and programming and want to obtain an overview of the technologies that are enabling component-based development. We introduce the idea of component-based development by defining the concept and providing its economic rationale. We describe how object-oriented programming evolved into local component models, such as Java Beans and distributed object technologies, such as the Common Object Request Broker Architecture (CORBA), Java Remote Method Invocation (RMI) and the Component Object Model (COM). We then address how these technologies matured into distributed component models, in particular Enterprise Java Beans (EJB) and the CORBA Component Model (CCM). We give an assessment of the maturity of each of these technologies and sketch how they are used to build distributed architectures.

Simulation of distributed processing networks

Abstract A discrete event simulator named DDPSIM for distributed processing networks is presented. The simulator which was initially developed to support the design of a distributed processing system for an air defense application, has continued to evolve to accommodate a more general class of bus-connected networks in which software modules, or tasks, are distributed. It has also been used to model a complex air traffic control application which involved multiple networks. The modular organization and various distributed network component models of the simulator are described in detail. The simulator provides user friendly interfaces that include simple input conventions for system definition, and tabular and graphic outputs for comprehensive analyses of the simulation results. A relatively complex distributed processing system for air traffic control is used as an example to illustrate the simulation procedure and to show the simulation results. To conclude, the lessons learned from the experience in simulation are discussed.