System modeling

During the last glacial-interglacial cycle, northern hemispheric (NH) ice-sheets experienced dramatic changes in radiative forcing, due to orbitally-driven insolation changes and varying greenhouse gas concentrations. This direct forcing caused temperature changes and eventually ablation anomalies. Orbital-scale variations in the atmospheric circulation caused anomalies in temperature advection and precipitation/snowfall that also strongly contributed to the mass balance and hence the time-evolution

The Zero Emissions Research and Technology (ZERT) project at the Los Alamos National Laboratory is studying the injection of CO2 into geologic repositories. We are formulating the problem as science based decision framework that can address issues of risk, cost, and technical requirements at all stages of the sequestration process. The framework is implemented in a sys tem model that is capable of performing stochastic simulations to address uncertainty in different geologic sequestration sc enarios, including injection into poorly characterized brine aquifers. Processes level laboratory experiments, field experiments, modeling, economic data, and risk theory are used to support the system level model that will be the basis for decision making. The current system model, CO2-PENS, is already proving to b e useful in showing complex interactions between the different components of the framework. The system model also provides a consistent platform to document decisions made during the...

We discuss some theoretical models for vital signs monitoring by using a UWB radar. Focusing attention on the respiration and heartbeat signals, we show the impact of relevant parameters, like the sampling time interval, on the ability to extract the desired signal parameters from the waveforms elaborated at the receiver. The role of the UWB pulse shape is also highlighted. With reference to more refined methods based on signal correlation, we propose a variant that does not need the availability of a locally generated reference signal and achieves good resolution for the movement detection, while ensuring limited processing times.

Model-based selective regression testing promises reduction in cost and labour by selecting a subset of the test suite corresponding to the modifications after system evolution. However, identification of modifications in the systems and selection of corresponding test cases is challenging due to interdependencies among models. State-based testing is an important approach to test the system behaviour. Unfortunately the existing state-based regression testing approaches do not care for dependencies of the state machine with other system models. This paper presents the tool support and evaluation of our statebased selective regression testing methodology for evolving state-based systems. START is an Eclipsebased tool for state-based regression testing compliant with UML 2.1 semantics. START deals with dependencies of state machines with class diagrams to cater for the change propagation. We applied the START on a case study and our results show significant reduction in the test cases ...

This paper presents ArchiTRIO (Architectural TRIO), a new temporal logic language which combines a subset of the UML notation with a precise formal semantics inspired from the authors’ experiences. ArchiTRIO allows developers to use standard UML 2.0 notation to describe non-critical aspects of systems, but it also offers a complementary formal notation, fully integrated with the UML one, to represent those system aspects that require precise modeling.

Understanding the impact of root architecture on plant resource efficiency is important, in particular, in the light of upcoming shortages of mineral fertilizers and changed environmental conditions. In the 1950s, a great number of root systems of European cultivated plants were excavated and studied by L. Kutschera (1960). Her work gave enormous insight into the variety of root system architectures and helped to realize the importance of belowground processes to plant productivity. We analysed the resulting hand drawings by using mathematical modelling and found root system parameters for a newly developed parametric L-System model. In this way we were able to first reproduce the illustrations, second computationally analyse root system traits and finally access the dynamic root architecture development.

This work addresses analytically the impact of multi-cell, multi-operator interference on the overall radio resources when multiple operators co-exist and share a common pool of spectrum. We propose a centralised dynamic spectrum allocation (DSA) scheme that is able to measure the interference level and interact dynamically to minimise interference and enhance spectrum utilisation while maintaining a satisfactory level of QoS. Furthermore, a concise system model and framework able to describe the interaction among different operators is presented.

In this paper, the essence of design thinking and systems thinking is reviewed, analyzed, and synthesized. Although there are many valuable schools of systems thinking, I focus on both Banathy's and Senge's since there are design spirit embedded in their systems thinking. I attempt to ...

According to our recent proposal, an information system is a combination of a process model captured as a Petri Net with Identifiers, an information model specified in the first-order logic over finite sets with equality, and a specification of how the transitions in the net manipulate information facts. The Information Systems Modeling (ISM) Suite is an integrated environment for developing, simulating, and analyzing models of information systems, released under an open-source license. This paper presents the basic features of the ISM Suite.

This paper presents a 3D graphics engine which is specifically designed to minimize the hardware cost while providing sufficient computing capability for consumer electronics with small to medium screen sizes (up to 800times600) such as digital television. The presented 3D engine consists of a fixed full 3D graphics pipeline for both geometry and rendering operation. This engine provides a standard AHB interface that makes it easily to be integrated into an AMBA-based SoC. The development of the 3D engine has gone through a rigorous design process: starting from system modeling (using System-C), RTL implementation, hardware/software co-simulation and FPGA verification to test chip fabrication. This 3D engine provides 3.3 M vertices/s and 278 Mpixels/s in maximum performance at 139 MHz using 0.18 silicon technology with 987 K gates that is sufficient for most applications for digital television. At the same time, a complete OpenGL-ES 1.1 API, windowing system, Linux operating system, device driver and a 3D performance monitoring tool have been developed for our 3D engine. This performance monitoring tool provides run-time performance information include frame rate, triangle rate, pixel rate, involved OpenGL function list, function counts, memory utilization and etc. Moreover, a built-in real-time AHB bus tracer is also provided to monitor the bus activities of the 3D engine and other components on the system bus. The bus tracer captures on-chip bus signals at ether cycle accurate or transaction levels and applies real-time compression to both levels of signals. With the performance monitoring tool and the bus tracer, the 3D application developer can easily analyze the communication of the components and fine tune the 3D application to optimize the entire SoC system performance and to satisfy performance/cost constrains on consumer electronics. Both of the hardware and software have been carefully verified and demonstrated on FPGA using ARM versatile SoC develop board- .