scholarly journals Acoustic emissions in the valuation of the combustion chamber pressure of an engine

2021 ◽  
Vol 2102 (1) ◽  
pp. 012014
Author(s):  
J P Rojas Suárez ◽  
J A Pabón León ◽  
M S Orjuela Abril
Keyword(s):  
Internal Combustion Engines ◽  
Signal Reconstruction ◽  
Acoustic Emissions ◽  
Chamber Pressure ◽  
Pressure Measurements ◽  
Efficient Operation ◽  
Combustion Pressure ◽  
Reconstructed Signal ◽  
Mean Pressure ◽  
The Hilbert Transform

Abstract Internal combustion engines demand advanced monitoring methodologies to promote efficient operation; particularly, the combustion pressure plays a central role in the overall performance, which promotes the utilization of transducers that hinders. Therefore, the present study introduces an acoustic emission methodology that serves for indirect combustion pressure measurements. Accordingly, the compound methodology integrates the Hilbert transform and the complex cepstrum using neural networks to accomplish pressure signal reconstruction. Results demonstrated that the proposed methodology featured robust performance while estimating pressure signals as it mitigates the combined noise effect produced by variations in engine speed, engine load, and fuel type. Moreover, the reconstructed signal facilitated the determination of key performance parameters such as peak pressure, pressure timing, and effective mean pressure. Relative error amounted to less than 10%, which ratified the robustness of the indirect pressure measurements. In conclusion, acoustic signal techniques represent an adequate approach to estimate the combustion pressure at variable engine conditions.

scholarly journals Compressive sensing-based vibration signal reconstruction using sparsity adaptive subspace pursuit

2018 ◽  
Vol 10 (8) ◽  
pp. 168781401879087 ◽  
Author(s):  
Lin Zhou ◽  
Qianxiang Yu ◽  
Daozhi Liu ◽  
Ming Li ◽  
Shukai Chi ◽  
...  
Keyword(s):  
Compressive Sensing ◽  
Data Storage ◽  
Wireless Sensors ◽  
Signal Reconstruction ◽  
Estimation Method ◽  
Vibration Signal ◽  
Estimation Accuracy ◽  
Offshore Structure ◽  
Vibration Signals ◽  
Reconstructed Signal

Wireless sensors produce large amounts of data in long-term online monitoring following the Shannon–Nyquist theorem, leading to a heavy burden on wireless communications and data storage. To address this problem, compressive sensing which allows wireless sensors to sample at a much lower rate than the Nyquist frequency has been considered. However, the lower rate sacrifices the integrity of the signal. Therefore, reconstruction from low-dimension measurement samples is necessary. Generally, the reconstruction needs the information of signal sparsity in advance, whereas it is usually unknown in practical applications. To address this issue, a sparsity adaptive subspace pursuit compressive sensing algorithm is deployed in this article. In order to balance the computational speed and estimation accuracy, a half-fold sparsity estimation method is proposed. To verify the effectiveness of this algorithm, several simulation tests were performed. First, the feasibility of subspace pursuit algorithm is verified using random sparse signals with five different sparsities. Second, the synthesized vibration signals for four different compression rates are reconstructed. The corresponding reconstruction correlation coefficient and root mean square error are demonstrated. The high correlation and low error result mean that the proposed algorithm can be applied in the vibration signal process. Third, implementation of the proposed approach for a practical vibration signal from an offshore structure is carried out. To reduce the effect of signal noise, the wavelet de-noising technique is used. Considering the randomness of the sampling, many reconstruction tests were carried out. Finally, to validate the reliability of the reconstructed signal, the structure modal parameters are calculated by the Eigensystem realization algorithm, and the result is only slightly different between original and reconstructed signal, which means that the proposed method can successfully save the modal information of vibration signals.

Design and Experimental Results of Small-Scale Rotary Engines

2001 ◽  
Author(s):  
Kelvin Fu ◽  
Aaron J. Knobloch ◽  
Fabian C. Martinez ◽  
David C. Walther ◽  
Carlos Fernandez-Pello ◽  
...  
Keyword(s):  
Internal Combustion Engines ◽  
Microelectromechanical Systems ◽  
Combustion Engine ◽  
Lithium Ion ◽  
Internal Combustion ◽  
Specific Power ◽  
Small Scale ◽  
Efficient Operation ◽  
Rotary Engine ◽  
Rotary Engines

Abstract A research project is currently underway to develop small-scale internal combustion engines fueled by liquid hydrocarbons. The ultimate goal of the MEMS Rotary Internal Combustion Engine Project is to develop a liquid hydrocarbon fueled MEMS-size rotary internal combustion micro-engine capable of delivering power on the order of milli-watts. This research is part of a larger effort to develop a portable, autonomous power generation system with an order of magnitude improvement in energy density over alkaline or lithium-ion batteries. The rotary (Wankel-type) engine is well suited for the fabrication techniques developed in the integrated chip (IC) community and refined by the MicroElectroMechanical Systems (MEMS) field. Features of the rotary engine that lend itself to MEMS fabrication are its planar construction, high specific power, and self-valving operation. The project aims at developing a “micro-rotary” engine with an epitrochoidal-shaped housing under 1 mm3 in size and with a rotor swept volume of 0.08 mm3. To investigate engine behavior and design issues, larger-scale “mini-rotary” engines have been fabricated from steel. Mini-rotary engine chambers are approximately 1000 mm3 to 1700 mm3 in size and their displacements range from 78 mm3 to 348 mm3. A test bench for the mini-rotary engine has been developed and experiments have been conducted with gaseous-fueled mini-rotary engines to examine the effects of sealing, ignition, design, and thermal management on efficiency. Preliminary testing has shown net power output of up to 2.7 W at 9300 RPM. Testing has been performed using hydrogen-air mixtures and a range of spark and glow plug designs as the ignition source. Iterative design and testing of the mini-engine has lead to improved sealing designs. These particular designs are such that they can be incorporated into the fabrication of the micro-engine. Design and fabrication of a first generation meso-scale rotary engine has been completed using a SiC molding process developed at Case Western Reserve University. The fabrication of the micro-rotary engine is being conducted in U.C. Berkeley’s Microfabrication Laboratory. Testing of the mini-engine has lead to the conclusion that there are no fundamental phenomena that would prevent the operation of the micro-engine. However, heat loss and sealing issues are key for efficient operation of the micro-engine, and they must be taken into account in the design and fabrication of the micro-rotary engine. The mini-rotary engine design, testing, results and applications will be discussed in this paper.

scholarly journals Statistical View on Phase and Magnitude Information in Signal Processing

2012 ◽  
Vol 47 (3) ◽  
pp. 127-136
Author(s):  
Waldemar Popiński
Keyword(s):  
Signal Processing ◽  
Time Domain ◽  
Signal Reconstruction ◽  
Time Domain Signal ◽  
Reconstructed Signal ◽  
Band Pass ◽  
Expected Values ◽  
Random Fluctuations ◽  
Phase Distortions ◽  
Complex Valued

Statistical View on Phase and Magnitude Information in Signal ProcessingIn this work the problem of reconstruction of an original complex-valued signalot,t= 0, 1, …,n- 1, from its Discrete Fourier Transform (DFT) spectrum corrupted by random fluctuations of magnitude and/or phase is investigated. It is assumed that the magnitude and/or phase of discrete spectrum values are distorted by realizations of uncorrelated random variables. The obtained results of analysis of signal reconstruction from such distorted DFT spectra concern derivation of the expected values and bounds on variances of the reconstructed signal at the observation moments. It is shown that the considered random distortions in general entail change in magnitude and/or phase of the reconstructed signal expected values, which together with imposed random deviations with finite variances can blur the similarity to the original signal. The effect of analogous random amplitude and/or phase distortions of a complex valued time domain signal on band pass filtration of distorted signal is also investigated.

scholarly journals Расчет параметров регенерации самоочищающихся фильтров смазочных систем судовых дизелей

2020 ◽  
Author(s):  
G.P. Kicha ◽  
A.V. Nadezkin ◽  
S.P. Boiko
Keyword(s):  
Internal Combustion Engines ◽  
Oil Pollution ◽  
Internal Combustion ◽  
Coarse Grained ◽  
Engine Oil ◽  
Battery Life ◽  
Combustion Engines ◽  
Adhesive Properties ◽  
Efficient Operation ◽  
Self Cleaning

Обоснована актуальность исследований рабочих процессов самоочищающегося фильтра, предназначенного для очистки моторного масла в двигателях внутреннего сгорания. Приведена методика расчета параметров регенерации автоматизированных фильтров, сформированных на базе модулей СРФ-60 и СРФД-120, позволяющая осуществлять выбор гидродинамического режима и времени обратной промывки фильтрующих элементов с учетом условий функционирования маслоочистителей. Выделено влияние на эффективность регенерации фильтровального процесса, идентифицированного удельной интенсивностью удаления дисперсной фазы из масла, гидродинамики (числа Рейнольдса) и относительного времени обратной промывки, адгезионных свойств отложений, особенностей конструкции фильтра, дисперсности загрязнений. Представлены доказательства адекватности расчетно-экспериментальных зависимостей, полученных по результатам лабораторных испытаний модели фильтра, и соответствия их данным эксплуатационных натурных испытаний самоочищающихся фильтров на судах. Показана возможность расчета и корректировки срока автономной работы самоочищающегося фильтра в смазочных системах судовых дизелей с учетом форсирования дизеля, качества применяемых горюче-смазочных материалов, интенсивности старения масла, срабатывания входящих в него присадок и уровня загрязнения крупнозернистыми механическими примесями. Дано заключение, что комбинированная очистка масла в двигателях внутреннего сгорания с использованием байпасной схемы сепарирования и центрифугирования облегчает функционирование полнопоточно подключаемых в систему смазки автоматизированных фильтров и позволяет увеличить срок автономной работы их до 5 тыс. ч. При этом надежная и эффективная работа очистителей возможна в самых жестких условиях загрязнения и старения масла.The relevance of research on the working processes of a self-cleaning filter intended for cleaning engine oil in internal combustion engines is substantiated. A methodology for calculating the regeneration parameters of automated filters generated by the SRF-60 and SRFD-120 modules is presented. The influence on the efficiency of the regeneration of the filtering process, which is identified by the specific intensity of the removal of the dispersed phase from the oil, the hydrodynamics (Reynolds number) and the relative backwash time, the adhesive properties of the sediments, the design features of the filter, and the dispersion of contaminants are highlighted. The evidence of the adequacy of the calculated experimental dependencies obtained from laboratory tests of the filter model and their compliance with the data of field tests of self-cleaning filters on ships is presented. The possibility of calculating and adjusting the autonomous work of the self-cleaning filter in the lubrication systems of marine diesel engines is shown taking into account the forcing of the diesel engine, the quality of the fuels and lubricants used, the aging rate of the oil, the operation of its additives and the level of contamination with coarse-grained mechanical admixture. It is concluded that the combined cleaning of oil in internal combustion engines using a bypass separation and centrifugation scheme facilitates the functioning of fully automated filters in the lubrication system and allows them to increase their battery life up to five thousand hours. Reliable and efficient operation of the purifiers is possible in the harshest conditions of oil pollution and aging.

scholarly journals ANALYSIS OF THERMODYNAMIC PROCESSES IN DIESEL ENGINES

2019 ◽  
pp. 46-52
Author(s):  
Sergey Aleksandrovich Kargin ◽  
Alexander Fedorovich Dorokhov ◽  
Nikolay Frolovich Popov
Keyword(s):  
Internal Energy ◽  
Internal Combustion Engines ◽  
Thermodynamic System ◽  
Mathematical Form ◽  
Efficient Operation ◽  
The Law ◽  
Economic Indices ◽  
External Forces ◽  
High Level ◽  
Fuel Evaporation

The article analyzes the first law of thermodynamics in terms of the classical law of energy conservation for thermodynamic systems formulated by J. R. Mayer, J. P. Joule and L. Helmholtz, as applied to contemporary piston engines with compression mixture in diesels. The prevailing factor in the system functioning (diesel engine) is the internal energy of a working mixture, rather than the heat input, as it was in the classical treatment of the first thermodynamic law. That is why, the wording of the law should be usefully changed from “heat delivered to the thermodynamic system is used for changing its internal energy and doing work against external forces” to “internal energy of a thermodynamic system determines the amount of heat given off inside the system and amount of work against external forces”. The mathematical form of the law and graphical interpretation of the theoretical thermodynamic Trinkler-Sabathe cycle are modified, accordingly. It has been stated that in practice the achievement of high technical and economic indices is provided by increasing the quality of working mixture: complete fuel evaporation in hot and moving medium, air/fuel ratio in the mixture in line with adopted standards of air/fuel proportion, high level of mixture homogeneity. The initial index to ensure highly efficient operation for reciprocating internal-combustion engines will be the internal energy of the working mixture which will determine the amount of heat emitted in the cylinder during mixture combustion and the amount of completed work against external forces.

scholarly journals Feature Extraction for Bearing Fault Detection Using Wavelet Packet Energy and Fast Kurtogram Analysis

2020 ◽  
Vol 10 (21) ◽  
pp. 7715
Author(s):  
Xiaojun Zhang ◽  
Jirui Zhu ◽  
Yaqi Wu ◽  
Dong Zhen ◽  
Minglu Zhang
Keyword(s):  
Feature Extraction ◽  
Fault Detection ◽  
Simulation Analysis ◽  
Wavelet Packet ◽  
Signal Reconstruction ◽  
Rolling Bearing ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Integrated Method ◽  
Reconstructed Signal

An integrated method for fault detection of bearing using wavelet packet energy (WPE) and fast kurtogram (FK) is proposed. The method consists of three stages. Firstly, several commonly used wavelet functions were compared to select the appropriate wavelet function for the application of WPE. Then the analyzed signal is decomposed using WPE and the energy of each decomposed signal is calculated and selected for signal reconstruction. Secondly, the reconstructed signal is analyzed by FK to select the best central frequency and bandwidth for the band-pass filter. Finally, the filtered signal is processed using the squared envelope frequency spectrum and compared with the theoretical fault characteristic frequency for fault feature extraction. The procedure and performance of the proposed approach are illustrated and estimated by the simulation analysis, proving that the proposed method can effectively extract the weak transients. Moreover, the analysis results of gearbox bearing and rolling bearing cases show that the proposed method can provide more accurate fault features compared with the individual FK method.

Velopharyngeal Insufficiency in Woodwind and Brass Players

2004 ◽  
Vol 19 (1) ◽  
pp. 21-25
Author(s):  
B Schwab ◽  
A Schultze-Florey
Keyword(s):  
Music Teachers ◽  
Medical Literature ◽  
Musical Training ◽  
Symphony Orchestra ◽  
Velopharyngeal Insufficiency ◽  
Music Students ◽  
Pressure Measurements ◽  
Brass Players ◽  
Mean Pressure ◽  
Intraoral Pressure

Velopharyngeal insufficiency (VPI) has received little attention in the medical literature. The aim of the present study was to determine the extent to which VPI constitutes a problem for woodwind and brass musicians. A total of 148 musicians (professionals from a symphony orchestra and students, the latter mainly from a national youth orchestra) were asked if they were aware of the phenomenon of VPI and whether they experienced it. Intraoral pressure measurements were performed to determine pressure peaks, mean pressure, and maximum attainable pressures. Of the 148 musicians, 81 were aware of the VPI disorder, and 24 of them showed symptoms of it themselves. Six of the affected musicians reported that VPI occurred in association with colds or stress or the playing of extremely high notes. One musician noted that it occurred only on return from vacation leave. Of the symptom-free musicians, 15% reported that they noticed symptoms of VPI during their musical training but that these gradually dissipated of their own accord. VPI in woodwind and brass instrumentalists is obviously more common than previously recognized. Despite reports in the medical literature that predominantly young musicians are affected, in our study only 47% of the individuals with symptoms were school pupils or music students (who overall constituted 41% of the study subjects). Oboists and clarinettists were the most frequently affected, perhaps because they develop relatively high mean pressures. Although VPI frequently occurs when woodwind and brass musicians are undergoing training and then regresses, it may persist, particularly in instrumentalists in whom high mean pressures form. To prevent persistent VPI, it seems advisable for music teachers to perform pressure measurements during instructional periods.

Engine Control Using Cylinder Pressure: Past, Present, and Future

1993 ◽  
Vol 115 (2B) ◽  
pp. 343-350 ◽  
Author(s):  
J. David Powell
Keyword(s):  
Internal Combustion Engines ◽  
Combustion Engines ◽  
Engine Control ◽  
Pressure Measurements ◽  
Cylinder Pressure ◽  
Automotive Engine ◽  
Spark Timing ◽  
The Cost ◽  
Misfire Detection ◽  
Charge Temperature

Research into the use of cylinder pressure measurements from reciprocating internal combustion engines for real time automotive engine control has been investigated for the last 20 years. The measurement has been investigated for spark timing, fuel-air ratio control, charge temperature measurements, and misfire detection. The cost of the sensors has inhibited widespread use in production vehicles; however, it was introduced in domestic Japanese production for spark control five years ago. Its use for misfire detection is also being actively considered.

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