Application of Prognostics and Health Management (PHM) to Software System Fault and Remaining Useful Life (RUL) Prediction

Prognostics and Health Management (PHM) is an engineering discipline focused on predicting the point at which systems or components will no longer perform as intended. The prediction is often articulated as a Remaining Useful Life (RUL). RUL is an important decision-making tool for contingency mitigation, i.e., the prediction of an RUL (and its associated confidence) enables decisions to be made about how and when to maintain the system. PHM is generally applied to hardware systems in the electronics and non-electronics application domains. The application of PHM (and RUL) concepts has not been explored for application to software. Today, software (SW) health management is confined to diagnostic assessments that identify problems, whereas prognostic assessment potentially indicates when in the future a problem will become detrimental to the operation of the system. Relevant areas such as SW defect prediction, SW reliability prediction, predictive maintenance of SW, SW degradation, and SW performance prediction, exist, but all represent static models, built upon historical data — none of which can calculate an RUL. This paper addresses the application of PHM concepts to software systems for fault predictions and RUL estimation. Specifically, we wish to address how PHM can be used to make decisions for SW systems such as version update, module changes, rejuvenation, maintenance scheduling and abandonment. This paper presents a method to prognostically and continuously predict the RUL of a SW system based on usage parameters (e.g., numbers and categories of releases) and multiple performance parameters (e.g., response time). The model is validated based on actual data (on performance parameters), generated by the test beds versus predicted data, generated by a predictive model. Statistical validation (regression validation) has been carried out as well. The test beds replicate and validate faults, collected from a real application, in a controlled and standard test (staging) environment. A case study based on publicly available data on faults and enhancement requests for the open-source Bugzilla application is presented. This case study demonstrates that PHM concepts can be applied to SW systems and RUL can be calculated to make decisions on software version update or upgrade, module changes, rejuvenation, maintenance schedule and total abandonment.

Donkey Kong's Legacy

The article discusses forms of contamination between human and artificial intelligence in computational neuroscience and machine learning research. I begin with a deep dive into an experiment with the legacy microprocessor MOS 6502, conducted by two engineers working in computational neuroscience, to explain why and how machine learning algorithms are increasingly employed to simulate human cognition and behavior. Through the strategic use of the microprocessor as “model organism” and references to biological and psychological lab research, the authors draw attention to speculative research in machine learning, where arcade video games designed in the 1980s provide test beds for artificial intelligences under development. I elaborate on the politics of these test beds and suggest alternative avenues for machine learning research to avoid that artificial intelligence merely reproduces settler-colonialist politics in silico.

Radar Target Simulation for Vehicle-in-the-Loop Testing

Automotive radar sensors play a vital role in the current development of autonomous driving. Their ability to detect objects even under adverse conditions makes them indispensable for environment-sensing tasks in autonomous vehicles. As their functional operation must be validated in-place, a fully integrated test system is required. Radar Target Simulators (RTS) are capable of executing end-of-line, over-the-air validation tests by looping back a received and afterward modified radar signal and have been incorporated into existing Vehicle-in-the-Loop (ViL) test beds before. However, the currently available ViL test beds and the RTS systems that they consist of lack the ability to generate authentic radar echoes with respect to their complexity. The paper at hand reviews the current development stage of the research as well as commercial ViL and RTS systems. Furthermore, the concept and implementation of a new test setup for the rapid prototyping and validation of ADAS functions is presented. This represents the first-ever integrated radar validation test system to comprise multiple angle-resolved radar target channels, each capable of generating multiple radar echoes. A measurement campaign that supports this claim has been conducted.

The Problem of Success and Failure in Public-private Innovation Partnerships

Public-Private Innovation Partnerships (PPIPs) are increasingly used as a tool for addressing ‘wicked’ public sector challenges. ‘Innovation’ is, however, frequently treated as a ‘magic’ concept: used unreflexively, taken to be axiomatically ‘good’, and left undefined within policy programmes. Using McConnell’s framework of policy success and failure and a case study of a multi-level PPIP in the English health service (NHS Test Beds), this paper critically explores the implications of the mobilisation of innovation in PPIP policy and practice. We highlight how the interplay between levels (macro/micro and policy maker/recipient) can shape both emerging policies and their prospects for success or failure. The paper contributes to an understanding of PPIP success and failure by extending McConnell’s framework to explore inter-level effects between policy and innovation project, and demonstrating how the success of PPIP policy cannot be understood without recognising the particular political effects of ‘innovation’ on formulation and implementation.

Combination of constructed wetland and extensive green roof that uses growing media with added recycled materials

<p>As implementation of green roofs can require a large amount of natural resources, such as water and natural components of growing media, the green roof system that uses principles of circular economy was developed and tested. The objective of the study was to verify the performance of the novel concept of combination of constructed wetland and extensive green roof irrigated with pre-treated grey water. Furthermore, the growing medium of the extensive part of the roof contains fractions of recycled crushed brick and pyrolyzed sewage sludge (biochar). In order to design and select a suitable growing medium, 16 variants of substrates were prepared and tested for water holding capacity and water retention curves. Two small test beds were built to test the viability of the novel green roof concept. In order to assess the effect of pyrolyzed sewage sludge, only one experimental bed contained this material (9.5 vol. %), whereas the crushed brick was part of both substrates (37.5 vol. %). The concept of the constructed wetland-extensive green roof was assessed on the basis of water balance measurements, laboratory analyses of water samples taken from various parts of the experimental beds, temperature and water content measurements along the experimental bed´s layers height. Physical properties of the designed substrates such as maximum water capacity, bulk density, grain size, and pH were determined.</p><p>After the first six months of performance, the concept of the constructed wetland-extensive green roof seems to be viable. There are relatively low concentrations of nutrients (phosphorus and nitrogen) in the leachate from test beds, namely because the irrigation provides the water directly to the drainage layer, and nutrient-rich substrate enriched with biochar isn't leached by irrigation water. Concentrations of nutrients increase only in response to precipitation. The constructed wetland part of the system proven a high potential to reduce the concentration of the nutrient in pre‑treated grey water.</p><p>The vegetation formed by Sedum spp. carpets is prospering well on both test beds. Nutrients from biochar are apparently available for the vegetation. Therefore, the vegetation on the bed with biochar amended substrate shows more vigorous growth and higher evapotranspiration. Substrates amended with recycled materials developed in the study had comparable properties (maximum water capacity, bulk density, pH) with commercial substrates. The monitoring of test beds continues in order to understand better the processes affecting water quantity and quality in long-term perspective.</p>

Dual porosity effects in hydrological performance of extensive green roofs

<p>Artificial substrates for green infrastructure have different composition and properties compared to natural soils. The admixture of light porous minerals such as pumice or expanded clay is often used to decrease the substrate weight and to increase water storage capacity. On the other hand, it could lead to dual porosity character of substrates and may affect their retention properties.</p><p>The dual-continuum model S1D is used to asses water flow in extensive green roof test beds with artificial substrate. The model numerically solves dual set of Richards’ equations. The soil hydraulic properties are described using van Genuchten-Mualem approach. Selected model parameters were optimized using Levenberg-Marquardt algorithm.</p><p>Two green roof test beds located at the University Centre for Energy Efficient Buildings of the Czech Technical University in Prague are studied. The test beds are filled with 60 mm of extensive green roof substrate, planted with sedum cuttings, respectively 40 mm of substrate, planted with sedum carpet. The substrate is a mixture of spongilit (55 %), crushed expanded clay (30 %) and peat (15 %). The outflow from the test beds is registered by tipping bucket flowmeter and the moisture content within the soil substrate by TDR probes. The test bed with sedum carpet is also weighted. For complete hydrometeorological characterization, data from the nearby meteorological station are available.</p><p>Dual-continuum model provides higher flexibility and overall better agreement between measured and simulated variables. Further investigation of hydrological regime of such substrates and possible hysteresis of their soil water retention curve is needed.</p><p>The research was supported by the Czech Science Foundation under project number No. 20-00788S. Experimental work has been supported by the Ministry of Education, Youth and Sports within National Sustainability Programme I, project number LO1605.</p>