The paper introduces new techniques to reduce the potential for pole-slipping induced by control systems and presents a low-cost pole-slipping detection and recovery scheme for magnetic drive-trains ...(MDTs). For the first time, the paper shows that a combination of electromagnetic and load-torque excitations which individually are not greater than the maximum coupling torque can initiate pole-slipping. For applications where acceleration feedback is unavailable, the motor-side inertia is virtually increased with a tracking differentiator to provide feedback of acceleration. Subsequently, controller design and parameter optimization are discussed. Experimental measurements on a custom test facility verify the presented principles that low-bandwidth controller designs with low inertia ratios can accommodate a wider range of on-load startup torque and load-torque disturbances without pole-slipping. To address overload issues, a pole-slipping detection method based on the kurtosis of electromagnetic torque and a recovery strategy based on converting the state of pole-slipping into that of on-load startup are presented. Experimental results demonstrate that detecting slip anomalies without load-side information, and recovery from pole-slipping without auxiliary mechanical devices are both feasible.
The building and transportation sectors are responsible for the greatest proportion of energy consumption in cities. While they are intrinsically interlinked with urban built form and density, ...climate change and technological innovation are having an effect on their relative contributions. This paper aims to develop an optimisation framework to facilitate the identification of the most energy-efficient urban built forms and urban geometry for the future built environment that can be adapted to the changing climate and ongoing technological development. It examines future scenarios for the city of London as a temperate climate zone (as a case study), in 2050, and contrasts it with the present situation. Specifically, the impact of climate change along with the penetration of electric vehicles into the transportation system that can be charged via rooftop photovoltaics is investigated. This study initially develops the geometrical models of four selected urban built forms and, secondly, analyzes their energy performance using an urban energy simulation software. The results, showing the impact of future scenarios on building energy performance, urban built form and density, demonstrate that court and tunnel-court built forms show better energy performance for future development. It is therefore recommended that for future urban developments in London, deep plan court and tunnel-court buildings with a lower number of storeys and a large cut-off angle are more advantageous in terms of building energy to accommodate the expected climate change. Finally, results of simulation trials indicate that the total building energy demand in 2050 is considerably higher than in the present climate as a result of additional cooling load and electric vehicle charging load.
In this study, an assessment of the performance of an industrial gas turbine during compressor fouling conditions is undertaken. The assessment is carried out through performance diagnostic and ...prognostic methods. The diagnostic technique identifies and isolates faults in the components of the gas turbine, and considers the health parameter of the compressor (efficiency). The remaining useful life of the compressor is estimated by a degradation model that also considers the compressor efficiency health index. Compressor efficiency is estimated using a gas turbine real-time executable digital-twin. The digital-twin is integrated within a gas turbine system operating in the field. Data processing of the compressor efficiency is required to obtain a meaningful trend of the compressor health index. Results demonstrate that the diagnostic and prognostic methods applied to the problem of compressor health parameter estimated by the digital-twin can be a powerful tool to initiate maintenance actions on associated axial compressors prior to significant performance deterioration.
In this study, a sensor fault diagnostic system to detect/isolate and accommodate faults in sensors from an industrial gas turbine has been developed. The sensor fault diagnostic module is integrated ...with a gas turbine real-time executable digital-twin (RT xDT) reported in a previous study. The sensor fault diagnostic module of the digital-twin considers analytical sensor redundancy using a reference engine model to provide redundant estimates of measured engine variables. A Software-in-the-Loop (S-i-L) architecture and Hardware-in-the-Loop (H-i-L) facility are constructed to assess the sensor diagnostic module (fault detection/ fault isolation) during failure in sensors from the engine. The results demonstrated that if the discrepancy between virtual measurement (provided by digital-twin) and sensor measurement exceeds the prescribed tolerance levels, the sensor fault diagnostic logic determines the state of switching between the virtual and engine sensor measurements in a dual lane control configuration of the gas turbine control system. The sensor fault detection system implemented in the gas turbine RT xDT can be deployed onto a distributed control system of industrial gas turbines to diagnose sensor deficiencies and ensure continuous and safe operation of the gas turbine. Consequently, the developed system will increase engine availability and reliability by diagnosing engine operational deficiencies before severe failure.
The paper presents readily implementable approaches for fault detection and diagnosis （FDD） based on measurements from multiple sensor groups, for industrial systems. Specifically, the use of ...hierarchical clustering （HC） and self-organizing map neural networks （SOMNNs） are shown to provide robust and user-friendly tools for application to industrial gas turbine （IGT） systems. HC fingerprints are found for normal operation, and FDD is achieved by monitoring cluster changes occurring in the resulting dendrograms. Similarly, fingerprints of operational behaviour are also obtained using SOMNN based classification maps （CMs） that are initially determined during normal operation, and FDD is performed by detecting changes in their CMs. The proposed methods are shown to be capable of FDD from a large group of sensors that measure a variety of physical quantities. A key feature of the paper is the development of techniques to accommodate transient system operation, which can often lead to false-alarms being triggered when using traditional techniques if the monitoring algorithms are not first desensitized. Case studies showing the efficacy of the techniques for detecting sensor faults, bearing tilt pad wear and early stage pre-chamber burnout, are included. The presented techniques are now being applied operationally and monitoring IGTs in various regions of the world.
Accurate population estimates are important for monitoring the conservation status of species, but nocturnal burrow‐nesting seabirds are notoriously difficult to count. Storm petrel species ...(Hydrobatidae) are particularly challenging, as burrow entrances are indistinct and response rates to playback low and variable, leading to imprecise population estimates and poor ability to detect trends. Playback is also labour‐intensive, requiring several days of calibration trials to determine site‐ and year‐specific response rates. To test the viability of using infra‐red digital video technology to census storm petrels, we conducted a trial on European Storm Petrels Hydrobates pelagicus at their largest UK colony, Mousa (Shetland). Hourly activity rates recorded from infra‐red filming accurately predicted the number of Apparently Occupied Sites (AOS), but this relationship was stronger in natural habitats (boulder‐beach, rocks and scree) than in walls, where between‐night variation was high due to poor and variable image quality, as well as the flight behaviour of Storm Petrels around vertical structures. Few filming attempts failed completely, but image quality was poor on dark nights with rain or fog, and deteriorated during the season as night‐length increased. Playback accurately predicted AOS density in natural habitats, but overestimated total AOS in walls by 38%. Simulations suggest that for the same fieldwork sampling effort, infra‐red filming will generate slightly more precise AOS estimates compared with playback. Better illumination using infra‐red floodlights would increase detection rates on dark nights, probably resulting in greater precision, but the large amount of expensive equipment and reviewing time required currently make infra‐red filming costly and inefficient relative to playback. However, we recommend its use at sites that cannot otherwise be surveyed safely, or where disturbance is a concern.
This book contains the successful invited submissions 1–25 to a Special Issue of Energies on the subject area of “Electrical Power and Energy Systems for Transportation Applications”.
How does sentiment in a pitch affect an entrepreneur’s fundraising outcomes? Although research suggests that negativity in entrepreneurial “pitches” to investors adversely impacts resource ...acquisition, there is a lack of empirical research showing whether, and to what extent, this is true. We study over 30,000 entrepreneurial loan requests from one of the largest loan marketplaces to understand how the sentiment in text-only pitches to investors affects fundraising. In contrast to prior literature, we find that negatively-worded pitches are funded faster than positively-worded ones. We also find that negatively-worded pitches result in lower interest rates to entrepreneurs. Finally, we find that negatively-worded loans default less, suggesting that the benefits of negativity are not one-sided but two-sided: negativity helps both resource seekers and resource providers. Collectively, the results from our study reveal how negativity can be beneficial in impression management and offer fresh insights for the psychological foundations of entrepreneurship.
In this study, the inter-stage dynamic performance of a multistage axial compressor is simulated through a semi-empirical model constructed in the Matlab Simulink environment. A semi-empirical 1-D ...compressor model developed in a previous study has been integrated with a 0-D twin-shaft gas turbine model developed in the Simulink environment. Inter-stage performance data generated through a high-fidelity design tool and based on throughflow analysis are considered for the development of the inter-stage modeling framework. Inter-stage performance data comprise pressure ratio at various speeds with nominal variable stator guide vane (VGV) positions and with hypothetical offsets to them with respect to the gas generator speed (GGS). Compressor discharge pressure, fuel flow demand, GGS and power turbine speed measured during the operation of a twin-shaft industrial gas turbine are considered for the dynamic model validation. The dynamic performance of the axial-compressor, simulated by the developed modeling framework, is represented on the overall compressor map and individual stage characteristic maps. The effect of extracting air through the bleed port in the engine center-casing on transient performance represented on overall compressor map and stage performance maps is also presented. In addition, the dynamic performance of the axial-compressor with an offset in VGV position is represented on the overall compressor map and individual stage characteristic maps. The study couples the fundamental principles of axial compressors and a semi-empirical modeling architecture in a complementary manner. The developed modeling framework can provide a deeper understanding of the factors that affect the dynamic performance of axial compressors.
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