1,641 research outputs found
Input-output Conformance Testing for Channel-based Service Connectors
Service-based systems are software systems composed of autonomous components or services provided
by different vendors, deployed on remote machines and accessible through the web. One of the
challenges of modern software engineering is to ensure that such a system behaves as intended by its
designer. The Reo coordination language is an extensible notation for formal modeling and execution
of service compositions. Services that have no prior knowledge about each other communicate
through advanced channel connectors which guarantee that each participant, service or client, receives
the right data at the right time. Each channel is a binary relation that imposes synchronization
and data constraints on input and output messages. Furthermore, channels are composed together
to realize arbitrarily complex behavioral protocols. During this process, a designer may introduce
errors into the connector model or the code for their execution, and thus affect the behavior of a
composed service. In this paper, we present an approach for model-based testing of coordination
protocols designed in Reo. Our approach is based on the input-output conformance (ioco) testing
theory and exploits the mapping of automata-based semantic models for Reo to equivalent process
algebra specifications
Photovoltaic stand-alone modular systems, phase 2
The final hardware and system qualification phase of a two part stand-alone photovoltaic (PV) system development is covered. The final design incorporated modular, power blocks capable of expanding incrementally from 320 watts to twenty kilowatts (PK). The basic power unit (PU) was nominally rated 1.28 kWp. The controls units, power collection buses and main lugs, electrical protection subsystems, power switching, and load management circuits are housed in a common control enclosure. Photo-voltaic modules are electrically connected in a horizontal daisy-chain method via Amp Solarlok plugs mating with compatible connectors installed on the back side of each photovoltaic module. A pair of channel rails accommodate the mounting of the modules into a frameless panel support structure. Foundations are of a unique planter (tub-like) configuration to allow for world-wide deployment without restriction as to types of soil. One battery string capable of supplying approximately 240 ampere hours nominal of carryover power is specified for each basic power unit. Load prioritization and shedding circuits are included to protect critical loads and selectively shed and defer lower priority or noncritical power demands. The baseline system, operating at approximately 2 1/2 PUs (3.2 kW pk.) was installed and deployed. Qualification was successfully complete in March 1983; since that time, the demonstration system has logged approximately 3000 hours of continuous operation under load without major incident
On the Automated Synthesis of Enterprise Integration Patterns to Adapt Choreography-based Distributed Systems
The Future Internet is becoming a reality, providing a large-scale computing
environments where a virtually infinite number of available services can be
composed so to fit users' needs. Modern service-oriented applications will be
more and more often built by reusing and assembling distributed services. A key
enabler for this vision is then the ability to automatically compose and
dynamically coordinate software services. Service choreographies are an
emergent Service Engineering (SE) approach to compose together and coordinate
services in a distributed way. When mismatching third-party services are to be
composed, obtaining the distributed coordination and adaptation logic required
to suitably realize a choreography is a non-trivial and error prone task.
Automatic support is then needed. In this direction, this paper leverages
previous work on the automatic synthesis of choreography-based systems, and
describes our preliminary steps towards exploiting Enterprise Integration
Patterns to deal with a form of choreography adaptation.Comment: In Proceedings FOCLASA 2015, arXiv:1512.0694
Electrical noise reduction techniques contributing to improved data quality at the National Transonic Facility
In initial use, the high-speed digital data acquisition systems at Langley Research Center's National Transonic Facility produced data containing unacceptably high noise levels. Described is a process whereby the contributing noise sources were identified and eliminated. The effects of 60 Hz power, system grounding, EMI/RFI, and other problems are discussed and the corrective action taken is outlined. The overall effort resulted in an improvement of greater than 5:1 in system performance. Although the report describes a system specifically used for wind tunnel data acquisition, the corrective techniques employed are generally applicable to large scale high-speed data systems where signal resolution in the low microvolts range is important
Removing Physical Presence Requirements for a Remote and Automated World - API Controlled Patch Panel for Conformance Testing
Quality assurance test engineers at the UNH-InterOperability Lab must run tests that require driving and monitoring a selection of DC signals. While the number of signals is numerous, there are limited ports on the test equipment, and only a few signals need patching for any given test. The selection of signals may vary between the 209 different tests and must be re-routed frequently. Currently, testers must leave their desk to manually modify the test setup in another room. This posed a considerable issue at the onset of the COVID-19 Pandemic when physical access was not possible. In order to enable future remote testing and human-free automation, there is a need for a remote patching device. Such a device was designed, constructed, and deployed. The process of designing the product involved defining design constraints, developing conceptual designs, selecting components and generating an electrical schematic, prototyping and iterating PCB versions, and final deployment and testing of the product
A 12 GHz satellite video receiver: Low noise, low cost prototype model for TV reception from broadcast satellites
A 12-channel synchronous phase lock video receiver consisting of an outdoor downconverter unit and an indoor demodulator unit was developed to provide both low noise performance and low cost in production quantities of 1000 units. The prototype receiver can be mass produced at a cost under $1540 without sacrificing system performance. The receiver also has the capability of selecting any of the twelve assigned satellite broadcast channels in the frequency range 11.7 to 12.2 GHz
Earth Observatory Satellite system definition study. Report no. 5: System design and specifications. Part 1: Observatory system element specifications
The performance, design, and quality assurance requirements for the Earth Observatory Satellite (EOS) Observatory and Ground System program elements required to perform the Land Resources Management (LRM) A-type mission are presented. The requirements for the Observatory element with the exception of the instruments specifications are contained in the first part
System design and specifications. Earth Observatory Satellite system definition study (EOS)
A design summary of the Earth Observatory Satellite (EOS) is presented. The systems considered in the summary are: (1) the spacecraft structure, (2) electrical power modules, (3) communications and data handling module, (4) attitude determination module, (5) actuation module, and (6) solar array and drive module. The documents which provide the specifications for the systems and the equipment are identified
Partially distributed coordination with Reo and constraint automata
Algorithms and the Foundations of Software technolog
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