scholarly journals A New Life Prediction Scheme for Mechanical System with Considering the Mission Profile Switching

2020 ◽  
Vol 10 (2) ◽  
pp. 673
Author(s):  
Jiancheng Yin ◽  
Huailiang Zheng ◽  
Yuantao Yang ◽  
Minqiang Xu
Keyword(s):  
Mechanical System ◽  
Life Prediction ◽  
Relevance Vector Machine ◽  
Operating Conditions ◽  
Operating Condition ◽  
Engine Simulation ◽  
Prediction Scheme ◽  
Degradation Models ◽  
Trajectory Method ◽  
Mission Profile

The life prediction is crucial to guarantee the reliability and safety of the mechanical system. The current prediction methods predict the life only based on the historical usage pattern of the mechanical system, and do not consider the mission profile of the future working process. To realize the life prediction with considering the switching of mission profile, which is composed of different operating conditions, this paper proposes a new prediction scheme on the base of the similarity trajectory method (STM). Two main improvements are employed. First, the reference degradation models are constructed according to the predicted trend of each constant operating condition obtained by the relevance vector machine (RVM). Secondly, the life under specific mission profile is calculated through weighted aggregating the life of each constant operating condition. The proposed method is validated by a turbofan engine simulation data. The results show that the proposed method achieves an excellent predicted result, in which the predicted result is close to the actual result. In addition, the proposed method can deal with the problem of mission profile switching.

scholarly journals Rotating Machinery Remaining Useful Life Prediction Scheme Using Deep-Learning-Based Health Indicator and a New RVM

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Gang Zhang ◽  
Weige Liang ◽  
Bo She ◽  
Fuqing Tian
Keyword(s):  
Deep Learning ◽  
Life Prediction ◽  
Short Term Memory ◽  
Polynomial Regression ◽  
Relevance Vector Machine ◽  
Remaining Useful Life ◽  
Health Indicator ◽  
Time Frequency ◽  
Prediction Scheme ◽  
Useful Life

Remaining useful life (RUL) prediction plays a significant role in developing the condition-based maintenance and improving the reliability and safety of machines. This paper proposes a remaining useful life prediction scheme combining deep-learning-based health indicator and a new relevance vector machine. First, both one-dimensional time-series information and two-dimensional time-frequency maps are input into a hybrid deep-learning structure network consisting of convolutional neural network (CNN) and long short-term memory network (LSTM) to construct health indicator (HI). Then, the prediction results and confidence interval are calculated by a new RVM enhanced by a polynomial regression model. The proposed method is verified by the public PRONOSTIA bearing datasets. Experimental results demonstrate the effectiveness of the proposed method in improving the prediction accuracy and analyzing the prediction uncertainty.

scholarly journals An Improved Similarity Trajectory Method Based on Monitoring Data under Multiple Operating Conditions

2021 ◽  
Vol 11 (22) ◽  
pp. 10968
Author(s):  
Jiancheng Yin ◽  
Yuqing Li ◽  
Rixin Wang ◽  
Minqiang Xu
Keyword(s):  
Life Prediction ◽  
Operating Conditions ◽  
Monitoring Data ◽  
Data Repository ◽  
Morphological Pattern ◽  
The Public ◽  
Trajectory Method ◽  
The Common ◽  
Public Datasets ◽  
Candidate Set

With the complexity of the task requirement, multiple operating conditions have gradually become the common scenario for equipment. However, the degradation trend of monitoring data cannot be accurately extracted in life prediction under multiple operating conditions, which is because some monitoring data is affected by the operating conditions. Aiming at this problem, this paper proposes an improved similarity trajectory method that can directly use the monitoring data under multiple operating conditions for life prediction. The morphological pattern and symbolic aggregate approximation-based similarity measurement method (MP-SAX) is first used to measure the similarity between the monitoring data under multiple operating conditions. Then, the similar life candidate set, and corresponding weight are obtained according to the MP-SAX. Finally, the life prediction results of equipment under multiple operating conditions can be calculated by aggregating the similar life candidate set. The proposed method is validated by the public datasets from NASA Ames Prognostics Data Repository. The results show that the proposed method can directly and effectively use the original monitoring data for life prediction without extracting the degradation trend of the monitoring data.

OPERATIONAL STATE OF BRIDGES OF UKRAINE

2019 ◽  
pp. 57-68
Author(s):  
Larysa Bodnar ◽  
Petro Koval ◽  
Sergii Stepanov ◽  
Liudmyla Panibratets
Keyword(s):  
Management System ◽  
The State ◽  
Operating Conditions ◽  
Bridge Management ◽  
Bridge Management System ◽  
Program Complex ◽  
Operating Condition ◽  
Software Complex ◽  
Automatic Mode ◽  
The Status

A significant part of Ukrainian bridges on public roads is operated for more than 30 years (94 %). At the same time, the traffic volume and the weight of vehicles has increased significantly. Insufficient level of bridges maintenance funding leads to the deterioration of their technical state. The ways to ensure reliable and safe operation of bridges are considered. The procedure for determining the predicted operational status of the elements and the bridge in general, which has a scientific novelty, is proposed. In the software complex, Analytical Expert Bridges Management System (AESUM), is a function that allows tracking the changes in the operational status of bridges both in Ukraine and in each region separately. The given algorithm of the procedure for determining the predicted state of the bridge using a degradation model is described using the Nassie-Schneidermann diagram. The model of the degradation of the bridge performance which is adopted in Ukraine as a normative one, and the algorithm for its adaptation to the AESUM program complex with the function to ensure the probabilistic predicted operating condition of the bridges in the automatic mode is presented. This makes it possible, even in case of unsatisfactory performance of surveys, to have the predicted lifetime of bridges at the required time. For each bridge element it is possible to determine the residual time of operation that will allow predict the state of the elements of the structure for a certain period of time in the future. Significant interest for specialists calls for the approaches to the development of orientated perspective plans for bridge inspection and monitoring of changes in the operational status of bridges for 2009-2018 in Ukraine. For the analysis of the state of the bridge economy, the information is available on the distribution of bridges by operating state related to the administrative significance of roads, by road categories and by materials of the structures. Determining the operating state of the bridge is an important condition for making the qualified decisions as regards its maintenance. The Analytical Expert Bridges Management System (AESUM) which is implemented in Ukraine, stores the data on the monitoring the status of bridges and performs the necessary procedures to maintain them in a reliable and safe operating condition. An important result of the work is the ability to determine the distribution of bridges on the public roads of Ukraine, according to operating conditions established in the program complex of AESUM, which is presented in accordance with the data of the current year. In conditions of limited funding and in case of unsatisfactory performance of surveys, it is possible to make the reasonable management decisions regarding the repair and the reconstruction of bridges. Keywords: bridge management system, operating condition, predicted operating condition, model of degradation, bridge survey plan, highway bridge.

scholarly journals On the Lifetime Estimation of SiC Power MOSFETs for Motor Drive Applications

Electronics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 324
Author(s):  
Carmelo Barbagallo ◽  
Santi Agatino Rizzo ◽  
Giacomo Scelba ◽  
Giuseppe Scarcella ◽  
Mario Cacciato
Keyword(s):  
Electric Drive ◽  
Average Power ◽  
Estimation Procedure ◽  
General Purpose ◽  
Operating Conditions ◽  
Power Losses ◽  
Power Devices ◽  
Lifetime Estimation ◽  
Power Mosfets ◽  
Mission Profile

This work presents a step-by-step procedure to estimate the lifetime of discrete SiC power MOSFETs equipping three-phase inverters of electric drives. The stress of each power device when it is subjected to thermal jumps from a few degrees up to about 80 °C was analyzed, starting from the computation of the average power losses and the commitment of the electric drive. A customizable mission profile was considered where, by accounting the working conditions of the drive, the corresponding average power losses and junction temperatures of the SiC MOSFETs composing the inverter can be computed. The tool exploits the Coffin–Manson theory, rainflow counting, and Miner’s rule for the lifetime estimation of the semiconductor power devices. Different operating scenarios were investigated, underlying their impact on the lifetime of SiC MOSFETs devices. The lifetime estimation procedure was realized with the main goal of keeping limited computational efforts, while providing an effective evaluation of the thermal effects. The method enables us to set up any generic mission profile from the electric drive model. This gives us the possibility to compare several operating scenario of the drive and predict the worse operating conditions for power devices. Finally, although the lifetime estimation tool was applied to SiC power MOSFET devices for a general-purpose application, it can be extended to any type of power switch technology.

Design Point for Predicting Year-Round Performance of Solar Parabolic Trough Concentrator Systems

2013 ◽  
Author(s):  
Men Wirz ◽  
Matthew Roesle ◽  
Aldo Steinfeld
Keyword(s):  
Operating Conditions ◽  
Transfer Model ◽  
Parabolic Trough ◽  
Specific System ◽  
Simple Method ◽  
Operating Condition ◽  
Average Efficiency ◽  
Design Point ◽  
Yearly Average ◽  
Solar Field

Thermal efficiencies of the solar field of two different parabolic trough concentrator (PTC) systems are evaluated for a variety of operating conditions and geographical locations, using a detailed 3D heat transfer model. Results calculated at specific design points are compared to yearly average efficiencies determined using measured direct normal solar irradiance (DNI) data as well as an empirical correlation for DNI. It is shown that the most common choices of operating conditions at which solar field performance is evaluated, such as the equinox or the summer solstice, are inadequate for predicting the yearly average efficiency of the solar field. For a specific system and location, the different design point efficiencies vary significantly and differ by as much as 11.5% from the actual yearly average values. An alternative simple method is presented of determining a representative operating condition for solar fields through weighted averages of the incident solar radiation. For all tested PTC systems and locations, the efficiency of the solar field at the representative operating condition lies within 0.3% of the yearly average efficiency. Thus, with this procedure, it is possible to accurately predict year-round performance of PTC systems using a single design point, while saving computational effort. The importance of the design point is illustrated by an optimization study of the absorber tube diameter, where different choices of operating conditions result in different predicted optimum absorber diameters.

Design and Performance of a Controlled Turbocharging System on Marine Diesel Engines

2006 ◽  
Author(s):  
Ioannis Vlaskos ◽  
Ennio Codan ◽  
Nikolaos Alexandrakis ◽  
George Papalambrou ◽  
Marios Ioannou ◽  
...  
Keyword(s):  
Steady State ◽  
Engine Performance ◽  
Operating Conditions ◽  
Electric Actuator ◽  
Engine Simulation ◽  
Engine Control System ◽  
Turbocharging System ◽  
Compressor Impeller ◽  
Marine Diesel ◽  
And Performance

The paper describes the design process for a controlled pulse turbocharging system (CPT) on a 5 cylinder 4-stroke marine engine and highlights the potential for improved engine performance as well as reduced smoke emissions under steady state and transient operating conditions, as offered by the following technologies: • controlled pulse turbocharging, • high pressure air injection onto the compressor impeller as well as into the air receiver, and • an electronic engine control system, including a hydraulic powered electric actuator. Calibrated engine simulation computer models based on the results of tests performed on the engine in its baseline configuration were used to design the CPT components. Various engine tests with CPT under steady state and transient operating conditions show the engine optimization process and how the above-mentioned technologies benefit engine behavior in both generator and propeller law operation.

Analytical determination of the optimal clearance for the fatigue life of ball bearing under different load conditions

2021 ◽  
pp. 1-28
Author(s):  
Bin Fang ◽  
Jinhua Zhang
Keyword(s):  
Fatigue Life ◽  
Load Distribution ◽  
Life Prediction ◽  
Ball Bearing ◽  
Operating Conditions ◽  
Analytical Determination ◽  
Parameters Selection ◽  
Bearing Life ◽  
Structural Design Optimization ◽  
Load Conditions

Abstract In this paper, a comprehensive analytical model for the fatigue life prediction of ball bearing in various operating conditions is presented. Not only the internal clearance variations induced by the centrifugal expansion and assembly interference, but also ball inertia forces and ball-raceway separations are fully considered in theoretical modeling to achieve accurate life prediction of ball bearing. The model has been validated by comparison with the static results in previous literature. Based on this, the results of the load distribution and fatigue life versus the internal clearance of ball bearing under various operating conditions are studied. The results show that there is always an optimal clearance to maximize bearing fatigue life for the radial load or the combined load conditions, and the size of the optimal clearance for bearing life is determined by both the load conditions and rotating speeds to ensure the uniformity of the internal load distribution of the ball bearing. Therefore, the above theoretical and conclusions can be used in structural design optimization and assembly parameters selection of ball bearing to maximize the life characteristic.

scholarly journals Impact of Number of Operators and Distance to Branch Piles on Woodchipper Operation

Forests ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 598 ◽  
Author(s):  
Łukasz Warguła ◽  
Mateusz Kukla ◽  
Piotr Krawiec ◽  
Bartosz Wieczorek
Keyword(s):  
Low Power ◽  
Adaptive Systems ◽  
Operating Time ◽  
Operating Mode ◽  
Operating Conditions ◽  
Operating Condition ◽  
Time Frequency ◽  
Drive Speed ◽  
Type Machine ◽  
Volume Output

Branch chipping machines with low-power engines are distinguished with an intermittent operation due to a periodical supply of branches. A conventional drive speed control of these machines is not adapted to adjust the operating mode depending on frequency of material supply for shredding. This article discusses the issues related to the assessment of the application of adaptive systems similar in design to start–stop systems used in vehicles, as necessary in the driving of this type machine. During testing, an impact of a distance between a branch pile from the woodchipper, a number of operators on frequency of drive unit operating condition changes, and the mass and volume output (productivity) were considered. A percentage ratio of the active and passive (idle) operation in selected conditions of use was also determined. A low-power 9.5 kW engine-powered cylindrical-type woodchipper was used for testing. Material chopped in the chipper was freshly cut branches of oaks (Quercus L. Sp. Pl. 994. 1753) with a diameter in the largest cross-section ca. 80 mm and moisture content ca. 25%. Piles of branches were located at three different distances from the chipper, i.e., 3 m, 9 m and 15 m. Branches to the chipper were fed by one or two operators. It was demonstrated that the idle run time in tested conditions with one operator could be from 43% to 71% of the entire operating time. Frequency of operating condition changes when only one operator worked and fluctuated from ca. 6 to 2 times per minute. Increasing the number of operators from one to two had a slight impact on the frequency of operating condition changes (by ca. 7%) at the shortest distance from the chipper (3 m). However, at larger distances, the additional operator may increase the frequency of operating condition changes of the chipper by 77% for 9 m distance and 85% for 15 m distance. The mass and volumetric output of the cylindrical chipper in the most advantageous case is equal to 0.66 t/h and 3.5 m3/h, respectively. The increase of the branch pile distance from the chipper causes a drop in mass output by 32%, and volumetric output by 33.5%. The results of the tests confirmed the necessity for the development of low-power chipping machines designed for clearing operations rather than industrial production of biomass. A direction for development could be systems that adapt driving units to operating conditions, depending on a demand for the chipping process.

Rolling bearing remaining useful life prediction via weight tracking relevance vector machine

2020 ◽  
Vol 32 (2) ◽  
pp. 024006
Author(s):  
Jian Tang ◽  
Guanhui Zheng ◽  
Dong He ◽  
Xiaoxi Ding ◽  
Wenbin Huang ◽  
...  
Keyword(s):  
Life Prediction ◽  
Rolling Bearing ◽  
Relevance Vector Machine ◽  
Remaining Useful Life ◽  
Useful Life
Sign in / Sign up

Export Citation Format

Share Document