Towards the text compression based feature extraction in high impedance fault detection

High impedance faults of medium voltage overhead lines with covered conductors can be identified by the presence of partial discharges. Despite it is a subject of research for more than 60 years, online partial discharges detection is always a challenge, especially in environment with heavy background noise. In this paper, a new approach for partial discharge pattern recognition is presented. All results were obtained on data, acquired from real 22 kV medium voltage overhead power line with covered conductors. The proposed method is based on a text compression algorithm and it serves as a signal similarity estimation, applied for the first time on partial discharge pattern. Its relevancy is examined by three different variations of classification model. The improvement gained on an already deployed model proves its quality.Web of Science1211art. no. 214

Intelligent Scheduling and Memory Management Techniques for Modern GPU Architectures

abstract: With the massive multithreading execution feature, graphics processing units (GPUs) have been widely deployed to accelerate general-purpose parallel workloads (GPGPUs). However, using GPUs to accelerate computation does not always gain good performance improvement. This is mainly due to three inefficiencies in modern GPU and system architectures. First, not all parallel threads have a uniform amount of workload to fully utilize GPU’s computation ability, leading to a sub-optimal performance problem, called warp criticality. To mitigate the degree of warp criticality, I propose a Criticality-Aware Warp Acceleration mechanism, called CAWA. CAWA predicts and accelerates the critical warp execution by allocating larger execution time slices and additional cache resources to the critical warp. The evaluation result shows that with CAWA, GPUs can achieve an average of 1.23x speedup. Second, the shared cache storage in GPUs is often insufficient to accommodate demands of the large number of concurrent threads. As a result, cache thrashing is commonly experienced in GPU’s cache memories, particularly in the L1 data caches. To alleviate the cache contention and thrashing problem, I develop an instruction aware Control Loop Based Adaptive Bypassing algorithm, called Ctrl-C. Ctrl-C learns the cache reuse behavior and bypasses a portion of memory requests with the help of feedback control loops. The evaluation result shows that Ctrl-C can effectively improve cache utilization in GPUs and achieve an average of 1.42x speedup for cache sensitive GPGPU workloads. Finally, GPU workloads and the co-located processes running on the host chip multiprocessor (CMP) in a heterogeneous system setup can contend for memory resources in multiple levels, resulting in significant performance degradation. To maximize the system throughput and balance the performance degradation of all co-located applications, I design a scalable performance degradation predictor specifically for heterogeneous systems, called HeteroPDP. HeteroPDP predicts the application execution time and schedules OpenCL workloads to run on different devices based on the optimization goal. The evaluation result shows HeteroPDP can improve the system fairness from 24% to 65% when an OpenCL application is co-located with other processes, and gain an additional 50% speedup compared with always offloading the OpenCL workload to GPUs. In summary, this dissertation aims to provide insights for the future microarchitecture and system architecture designs by identifying, analyzing, and addressing three critical performance problems in modern GPUs.Dissertation/ThesisDoctoral Dissertation Computer Engineering 201

Branch Prediction For Network Processors

Originally designed to favour flexibility over packet processing performance, the future of the programmable network processor is challenged by the need to meet both increasing line rate as well as providing additional processing capabilities. To meet these requirements, trends within networking research has tended to focus on techniques such as offloading computation intensive tasks to dedicated hardware logic or through increased parallelism. While parallelism retains flexibility, challenges such as load-balancing limit its scope. On the other hand, hardware offloading allows complex algorithms to be implemented at high speed but sacrifice flexibility. To this end, the work in this thesis is focused on a more fundamental aspect of a network processor, the data-plane processing engine. Performing both system modelling and analysis of packet processing functions; the goal of this thesis is to identify and extract salient information regarding the performance of multi-processor workloads. Following on from a traditional software based analysis of programme workloads, we develop a method of modelling and analysing hardware accelerators when applied to network processors. Using this quantitative information, this thesis proposes an architecture which allows deeply pipelined micro-architectures to be implemented on the data-plane while reducing the branch penalty associated with these architectures

Experimental validation of a one-dimensional twin-entry radial turbine model under non-linear pulse conditions

This is the author¿s version of a work that was accepted for publication in International Journal of Engine Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published as https://doi.org/10.1177/1468087419869157[EN] This article presents the experimental validation of a complete integrated one-dimensional twin-scroll turbine model able to be used in reciprocating internal combustion engine unsteady simulations. A passenger car with a twin-entry-type turbine has been tested under engine-like pulse conditions by means of a specifically built gas stand. To obtain high-resolution quality data, the turbine and turbine line pipes have been instrumented with mean and instantaneous pressure sensors as well as temperature and mass flow sensors, employing a uniquely designed rotating valve for the pulse generation. This experimental configuration enables to obtain the pressure decomposition in both inlets and outlets of the turbine. Using the experimental data obtained, the model is fully validated, with special focus on the reflected and transmitted components for analysing the performance of the model and its non-linear acoustics prediction capabilities. The model presents a very high degree of correlation with the experimental results, providing a range of errors similar to the uncertainty of the measurements, even in the medium- and high-frequency spectra.The author(s) disclosed receipt of the following financial support for the research, authorship and/or publication of this article: This work was supported by the 'Ayuda a Primeros Proyectos de Investigacion' (PAID-06-18), Vicerrectorado de Investigacion, Innovacion y Transferencia de la Universitat Politecnica de Valencia (UPV), Valencia, Spain. P.S. was partially supported through contract FPI-2017-S2-1428 of Programa de Apoyo para la Investigacion y Desarrollo (PAID) of Universitat Politecnica de Valencia.Serrano, J.; Arnau Martínez, FJ.; García-Cuevas González, LM.; Soler-Blanco, P.; Cheung, R. (2021). Experimental validation of a one-dimensional twin-entry radial turbine model under non-linear pulse conditions. International Journal of Engine Research. 22(2):390-406. https://doi.org/10.1177/1468087419869157S390406222Watson, N., & Janota, M. S. (1982). Turbocharging the Internal Combustion Engine. doi:10.1007/978-1-349-04024-7Galindo, J., Fajardo, P., Navarro, R., & García-Cuevas, L. M. (2013). Characterization of a radial turbocharger turbine in pulsating flow by means of CFD and its application to engine modeling. Applied Energy, 103, 116-127. doi:10.1016/j.apenergy.2012.09.013Torregrosa, A. J., Broatch, A., Navarro, R., & García-Tíscar, J. (2014). Acoustic characterization of automotive turbocompressors. International Journal of Engine Research, 16(1), 31-37. doi:10.1177/1468087414562866Serrano, J. R., Tiseira, A., García-Cuevas, L. M., Inhestern, L. B., & Tartoussi, H. (2017). Radial turbine performance measurement under extreme off-design conditions. Energy, 125, 72-84. doi:10.1016/j.energy.2017.02.118Piscaglia, F., Onorati, A., Marelli, S., & Capobianco, M. (2018). A detailed one-dimensional model to predict the unsteady behavior of turbocharger turbines for internal combustion engine applications. International Journal of Engine Research, 20(3), 327-349. doi:10.1177/1468087417752525Galindo, J., Arnau, F. J., García-Cuevas, L. M., & Soler, P. (2018). Experimental validation of a quasi-two-dimensional radial turbine model. International Journal of Engine Research, 21(6), 915-926. doi:10.1177/1468087418788502Rajoo, S., Romagnoli, A., & Martinez-Botas, R. F. (2012). Unsteady performance analysis of a twin-entry variable geometry turbocharger turbine. Energy, 38(1), 176-189. doi:10.1016/j.energy.2011.12.017Rajoo, S., & Martinez-Botas, R. (2008). Variable Geometry Mixed Flow Turbine for Turbochargers: An Experimental Study. International Journal of Fluid Machinery and Systems, 1(1), 155-168. doi:10.5293/ijfms.2008.1.1.155Copeland, C. D., Martinez-Botas, R., & Seiler, M. (2010). Comparison Between Steady and Unsteady Double-Entry Turbine Performance Using the Quasi-Steady Assumption. Journal of Turbomachinery, 133(3). doi:10.1115/1.4000580Copeland, C. D., Martinez-Botas, R., & Seiler, M. (2011). Unsteady Performance of a Double Entry Turbocharger Turbine With a Comparison to Steady Flow Conditions. Journal of Turbomachinery, 134(2). doi:10.1115/1.4003171Costall, A. W., McDavid, R. M., Martinez-Botas, R. F., & Baines, N. C. (2010). Pulse Performance Modeling of a Twin Entry Turbocharger Turbine Under Full and Unequal Admission. Journal of Turbomachinery, 133(2). doi:10.1115/1.4000566Yang, M., Martinez-Botas, R., Rajoo, S., Yokoyama, T., & Ibaraki, S. (2015). An investigation of volute cross-sectional shape on turbocharger turbine under pulsating conditions in internal combustion engine. Energy Conversion and Management, 105, 167-177. doi:10.1016/j.enconman.2015.06.038Copeland, C. D., Newton, P. J., Martinez-Botas, R., & Seiler, M. (2011). The Effect of Unequal Admission on the Performance and Loss Generation in a Double-Entry Turbocharger Turbine. Journal of Turbomachinery, 134(2). doi:10.1115/1.4003226Cerdoun, M., & Ghenaiet, A. (2018). Unsteady behaviour of a twin entry radial turbine under engine like inlet flow conditions. Applied Thermal Engineering, 130, 93-111. doi:10.1016/j.applthermaleng.2017.11.001Payri, F., Benajes, J., & Reyes, M. (1996). Modelling of supercharger turbines in internal-combustion engines. International Journal of Mechanical Sciences, 38(8-9), 853-869. doi:10.1016/0020-7403(95)00105-0Chiong, M. S., Rajoo, S., Martinez-Botas, R. F., & Costall, A. W. (2012). Engine turbocharger performance prediction: One-dimensional modeling of a twin entry turbine. Energy Conversion and Management, 57, 68-78. doi:10.1016/j.enconman.2011.12.001Chiong, M. S., Rajoo, S., Romagnoli, A., Costall, A. W., & Martinez-Botas, R. F. (2016). One-dimensional pulse-flow modeling of a twin-scroll turbine. Energy, 115, 1291-1304. doi:10.1016/j.energy.2016.09.041Galindo, J., Navarro, R., García-Cuevas, L. M., Tarí, D., Tartoussi, H., & Guilain, S. (2018). A zonal approach for estimating pressure ratio at compressor extreme off-design conditions. International Journal of Engine Research, 20(4), 393-404. doi:10.1177/1468087418754899Payri, F., Olmeda, P., Arnau, F. J., Dombrovsky, A., & Smith, L. (2014). External heat losses in small turbochargers: Model and experiments. Energy, 71, 534-546. doi:10.1016/j.energy.2014.04.096Serrano, J. R., Olmeda, P., Arnau, F. J., Dombrovsky, A., & Smith, L. (2015). Turbocharger heat transfer and mechanical losses influence in predicting engines performance by using one-dimensional simulation codes. Energy, 86, 204-218. doi:10.1016/j.energy.2015.03.130Gil, A., Tiseira, A. O., García-Cuevas, L. M., Usaquén, T. R., & Mijotte, G. (2018). Fast three-dimensional heat transfer model for computing internal temperatures in the bearing housing of automotive turbochargers. International Journal of Engine Research, 21(8), 1286-1297. doi:10.1177/1468087418804949Serrano, J. R., Olmeda, P., Tiseira, A., García-Cuevas, L. M., & Lefebvre, A. (2013). Theoretical and experimental study of mechanical losses in automotive turbochargers. Energy, 55, 888-898. doi:10.1016/j.energy.2013.04.042Piñero, G., Vergara, L., Desantes, J. M., & Broatch, A. (2000). Estimation of velocity fluctuation in internal combustion engine exhaust systems through beamforming techniques. Measurement Science and Technology, 11(11), 1585-1595. doi:10.1088/0957-0233/11/11/307Zimmermann, R., Baar, R., & Biet, C. (2016). Determination of the isentropic turbine efficiency due to adiabatic measurements and the validation of the conditions via a new criterion. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 232(24), 4485-4494. doi:10.1177/0954406216670683Serrano, J. R., Arnau, F. J., Gracía-Cuevas, L. M., Samala, V., & Smith, L. (2019). Experimental approach for the characterization and performance analysis of twin entry radial-inflow turbines in a gas stand and with different flow admission conditions. Applied Thermal Engineering, 159, 113737. doi:10.1016/j.applthermaleng.2019.113737Serrano, J. R., Olmeda, P., Páez, A., & Vidal, F. (2010). An experimental procedure to determine heat transfer properties of turbochargers. Measurement Science and Technology, 21(3), 035109. doi:10.1088/0957-0233/21/3/035109Serrano, J. R., Arnau, F. J., Dolz, V., Tiseira, A., & Cervelló, C. (2008). A model of turbocharger radial turbines appropriate to be used in zero- and one-dimensional gas dynamics codes for internal combustion engines modelling. Energy Conversion and Management, 49(12), 3729-3745. doi:10.1016/j.enconman.2008.06.031Serrano, J. R., Arnau, F. J., Fajardo, P., Reyes Belmonte, M. A., & Vidal, F. (2012). Contribution to the Modeling and Understanding of Cold Pulsating Flow Influence in the Efficiency of Small Radial Turbines for Turbochargers. Journal of Engineering for Gas Turbines and Power, 134(10). doi:10.1115/1.4007027Serrano, J. R., Arnau, F. J., García-Cuevas, L. M., Dombrovsky, A., & Tartoussi, H. (2016). Development and validation of a radial turbine efficiency and mass flow model at design and off-design conditions. Energy Conversion and Management, 128, 281-293. doi:10.1016/j.enconman.2016.09.032Chen, H., Hakeem, I., & Martinez-Botas, R. F. (1996). Modelling of a Turbocharger Turbine Under Pulsating Inlet Conditions. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy, 210(5), 397-408. doi:10.1243/pime_proc_1996_210_063_02Galindo, J., Serrano, J. R., Arnau, F. J., & Piqueras, P. (2009). Description of a Semi-Independent Time Discretization Methodology for a One-Dimensional Gas Dynamics Model. Journal of Engineering for Gas Turbines and Power, 131(3). doi:10.1115/1.2983015Van Leer, B. (1974). Towards the ultimate conservative difference scheme. II. Monotonicity and conservation combined in a second-order scheme. Journal of Computational Physics, 14(4), 361-370. doi:10.1016/0021-9991(74)90019-9Toro, E. F., Spruce, M., & Speares, W. (1994). Restoration of the contact surface in the HLL-Riemann solver. Shock Waves, 4(1), 25-34. doi:10.1007/bf01414629Courant, R., Friedrichs, K., & Lewy, H. (1928). �ber die partiellen Differenzengleichungen der mathematischen Physik. Mathematische Annalen, 100(1), 32-74. doi:10.1007/bf01448839Harris, F. J. (1978). On the use of windows for harmonic analysis with the discrete Fourier transform. Proceedings of the IEEE, 66(1), 51-83. doi:10.1109/proc.1978.10837Welch, P. (1967). The use of fast Fourier transform for the estimation of power spectra: A method based on time averaging over short, modified periodograms. IEEE Transactions on Audio and Electroacoustics, 15(2), 70-73. doi:10.1109/tau.1967.116190

Near-Instantaneously Adaptive HSDPA-Style OFDM Versus MC-CDMA Transceivers for WIFI, WIMAX, and Next-Generation Cellular Systems

Burts-by-burst (BbB) adaptive high-speed downlink packet access (HSDPA) style multicarrier systems are reviewed, identifying their most critical design aspects. These systems exhibit numerous attractive features, rendering them eminently eligible for employment in next-generation wireless systems. It is argued that BbB-adaptive or symbol-by-symbol adaptive orthogonal frequency division multiplex (OFDM) modems counteract the near instantaneous channel quality variations and hence attain an increased throughput or robustness in comparison to their fixed-mode counterparts. Although they act quite differently, various diversity techniques, such as Rake receivers and space-time block coding (STBC) are also capable of mitigating the channel quality variations in their effort to reduce the bit error ratio (BER), provided that the individual antenna elements experience independent fading. By contrast, in the presence of correlated fading imposed by shadowing or time-variant multiuser interference, the benefits of space-time coding erode and it is unrealistic to expect that a fixed-mode space-time coded system remains capable of maintaining a near-constant BER