scholarly journals Baseline-Free Adaptive Crack Localization for Operating Stepped Rotors Based on Multiscale Data Fusion

Sensors ◽  
2020 ◽  
Vol 20 (19) ◽  
pp. 5693
Author(s):  
Zhiwen Lu ◽  
Shancheng Cao ◽  
Rui Yuan ◽  
Yong Lv
Keyword(s):  
Data Fusion ◽  
Reference Model ◽  
Damage Index ◽  
Energy Operator ◽  
Noise Robustness ◽  
Experimental Investigations ◽  
Multiple Cracks ◽  
Practical Applications ◽  
Critical Issues ◽  
Baseline Information

Crack localization in running rotors is very important and full of challenges for machinery operation and maintenance. Characteristic deflection shapes or their derivatives based methods seem to be promising for crack localization in rotors. Despite the substantial advantages, several critical issues still need to be addressed to enhance the efficiency of this kind of method for practical applications. Two problems are considered in this work: 1. How to localize single or multiple cracks accurately avoiding the interference of commonly existing steps without baseline information on pristine rotors; 2. How to improve the crack localization performance under a noisy environment. To circumvent the issues, a novel baseline-free adaptive crack localization method is proposed based on data fusion of multiscale super-harmonic characteristic deflection shapes (SCDSs). In this method, crack induced asymmetry and nonlinearity of crack breathing are utilized to simultaneously eliminate the interference from the steps without a reference model. To enhance the noise robustness, the multiscale representations of SCDSs are made in Gaussian multiscale space, and Teager energy operator is applied to the multiscale SCDSs to amplify the crack induced singularities and construct the multiscale Teager super-harmonic characteristic deflection shapes (TSCDSs). Moreover, fractal dimension is designed as an evaluator to select the proper multiscale TSCDSs for data fusion adaptively. Then, a new damage index is derived for crack localization by Dempster-Shafer’s (D-S) evidence fusion of the adaptively selected multiscale TSCDSs. Finally, the feasibility and the effectiveness are verified by both numerical and experimental investigations.

scholarly journals Modules and Techniques for Motion Planning: An Industrial Perspective

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 420
Author(s):  
Stefano Quer ◽  
Luz Garcia
Keyword(s):  
Data Fusion ◽  
Autonomous Driving ◽  
Random Trees ◽  
Approximation Techniques ◽  
Main Research ◽  
Autonomous Cars ◽  
Critical Issues ◽  
Relative Errors ◽  
Path Planner ◽  
Many Core

Research on autonomous cars has become one of the main research paths in the automotive industry, with many critical issues that remain to be explored while considering the overall methodology and its practical applicability. In this paper, we present an industrial experience in which we build a complete autonomous driving system, from the sensor units to the car control equipment, and we describe its adoption and testing phase on the field. We report how we organize data fusion and map manipulation to represent the required reality. We focus on the communication and synchronization issues between the data-fusion device and the path-planner, between the CPU and the GPU units, and among different CUDA kernels implementing the core local planner module. In these frameworks, we propose simple representation strategies and approximation techniques which guarantee almost no penalty in terms of accuracy and large savings in terms of memory occupation and memory transfer times. We show how we adopt a recent implementation on parallel many-core devices, such as CUDA-based GPGPU, to reduce the computational burden of rapidly exploring random trees to explore the state space along with a given reference path. We report on our use of the controller and the vehicle simulator. We run experiments on several real scenarios, and we report the paths generated with the different settings, with their relative errors and computation times. We prove that our approach can generate reasonable paths on a multitude of standard maneuvers in real time.

scholarly journals Orthology between the genomes of Plasmodium falciparum and rodent malaria parasites: possible practical applications

2002 ◽  
Vol 357 (1417) ◽  
pp. 55-63 ◽  
Author(s):  
A. P. Waters
Keyword(s):  
Plasmodium Falciparum ◽  
Gene Function ◽  
Proteome Analysis ◽  
Experimental System ◽  
Genomic Research ◽  
Experimental Investigations ◽  
Practical Applications ◽  
Genome Data ◽  
Entire Sequence ◽  
Regulated Gene Expression

The work of the consortium that has been formed to complete the entire sequence of the genome of a selected clone of the human malaria parasite, Plasmodium falciparum , is almost finished. Already huge tracts of the genome are available as fully assembled chromosomes or large contigs and the work of initial annotation is in an advanced state. Post–genomic research is in one sense the process of furthering the process of annotation, creating biological atlases and preliminary attempts to make global descriptions of gene transcription and proteome analysis are underway. Comparison between significant amounts of genome data from both closely, and more distantly related organisms, can facilitate the identification of genes themselves, coordinately regulated gene expression groups, gene function and genome organization. Models of malaria can fulfil these functions and in addition provide an experimental system wherein predictions can be tested and basic experimental investigations performed within numerous aspects of disease, pathology, parasite–host and parasite–vector interactions. Comparative genomics in Plasmodium has already been shown to have informative roles in the completion of annotation and the elucidation of gene function. These roles will be illustrated by example and used as the basis for a discussion of the utility of genome information and malaria models in realizing the desired product of Plasmodium genomics, the development of malaria therapies.

Essential Features and Critical Issues With Educational Chatbots

2021 ◽  
pp. 246-262
Author(s):  
Jeremy Riel
Keyword(s):  
Artificial Intelligence ◽  
Machine Learning ◽  
Formal Learning ◽  
Automated Systems ◽  
Conversational Agents ◽  
Teacher Instruction ◽  
Practical Applications ◽  
Significant Potential ◽  
Critical Issues ◽  
Future Work

Conversational agents, also known as chatbots, are automated systems for engaging in two-way dialogue with human users. These systems have existed in one form or another for at least 60 years but have recently demonstrated significant potential with advances in machine learning and artificial intelligence technologies. The use of conversational agents or chatbots for education can potentially reduce costs and supplement teacher instruction in transformative ways for formal learning. This chapter examines the design and status of chatbots and conversational agents for educational purposes. Common design functions and goals of educational chatbots are described, along with current practical applications of chatbots for educational purposes. Finally, this chapter considers issues about pedagogical commitments, ethics, and equity to suggest future work in the field.

scholarly journals Structural Stability of Functionalized Silicene Nanoribbons with Normal, Reconstructed, and Hybrid Edges

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Sadegh Mehdi Aghaei ◽  
Ingrid Torres ◽  
Irene Calizo
Keyword(s):  
Structural Stability ◽  
First Principles ◽  
Experimental Investigations ◽  
First Principles Calculations ◽  
Zigzag Edge ◽  
Edge Structure ◽  
Practical Applications ◽  
Potential Applications ◽  
Silicene Nanoribbons ◽  
Significant Attention

Silicene, a novel graphene-like material, has attracted a significant attention because of its potential applications for nanoelectronics. In this paper, we have theoretically investigated the structural stability of edge-hydrogenated and edge-fluorinated silicene nanoribbons (SiNRs) via first-principles calculations. Various edge forms of SiNRs including armchair edge, zigzag edge, Klein edge, reconstructed Klein edge, reconstructed pentagon-heptagon edge, and hybrid edges have been considered. It has been found that fully fluorinated Klein edge SiNRs, in which each edge Si atom is terminated by three fluorine atoms, are the most stable structure. We also discovered that a hybrid edge structure of trihydrogenated Klein edge and dihydrogenated zigzag edge can increase the nanoribbon’s stability up to that of dihydrogenated armchair edge SiNR, which is known as the most stable edge-hydrogenated structure. With the attractive properties of silicene for practical applications, the obtained results will advance experimental investigations toward the development of silicene based devices.

Three-dimensional images generated from diffuse ultrasound wave: detections of multiple cracks in concrete structures

2019 ◽  
Vol 19 (1) ◽  
pp. 12-25 ◽  
Author(s):  
Hanyu Zhan ◽  
Hanwan Jiang ◽  
Ruinian Jiang
Keyword(s):  
Simultaneous Detection ◽  
Three Dimensional ◽  
Concrete Structures ◽  
Ultrasound Wave ◽  
Multiple Cracks ◽  
Scattering Media ◽  
Destructive Testing ◽  
Practical Applications ◽  
Sensitivity Kernel ◽  
Three Dimensional Images

The simultaneous detection of multiple defects in concrete structures is a task of pivotal importance for non-destructive testing and evaluation. Diffuse waves experiencing multiple scattering inside media are demonstrated to be sensitive to weak defects. Here, an analytic model is presented for diffuse wave decorrelation associated with sensitivity kernel that describes the time-of-flight distribution in strongly scattering environments. The model is then used for generating three-dimensional images that involve estimating perturbations at each localized position through an iterative, non-linear algorithm. With the consideration of loads and micro-cracks effects on diffuse waves, an application of the approach to a real-size concrete beam shows features that denote the positions and depths of multiple existing cracks. Extension of the approach to other strongly scattering media such as tissues and volcanos is straightforward. This study offers great potential for practical applications such as structural health monitoring, medical image generation, and seismic monitoring.

Detection of Multiple Cracks in Triangular Cantilevers Based on Frequency Measurements

2006 ◽  
Vol 324-325 ◽  
pp. 259-262
Author(s):  
Fei Wang ◽  
Xue Zeng Zhao ◽  
Jia Ying Chen
Keyword(s):  
Damage Index ◽  
Maximum Error ◽  
Crack Size ◽  
Force Sensors ◽  
Multiple Cracks ◽  
Cantilever Deflection ◽  
Local Flexibility ◽  
Small Force ◽  
The Relationship ◽  
Number Of Segments

Triangular cantilevers are used as small force sensors. Prediction of location and size of multiple cracks from experimental results will be of value to users and designers of cantilever deflection force sensors. We extend a method for prediction of location and size of multiple cracks in rectangular cantilevers to deal with triangular cantilevers in this paper. The cracks are assumed to introduce local flexibility change and are modeled as rotational springs. The beam is divided into a number of segments, and each segment is associated with a damage index, which can be calculated through the relationship between the damage index and strain energy of each segment and the changes in the frequencies caused by the cracks. The location of cracks can be obtained with high accuracy with sufficient segment numbers. The size of a crack can be calculated through the relationship between the crack size and its stiffness, which can be obtained from the damage index related to the crack. The maximum error in prediction of the crack position in the case of double cracks is less than 15%, and it is less than 25% in prediction of the crack size.

scholarly journals Big Data of Source of Statistical Information: On the Example of the Book Publishing Industry

2019 ◽  
pp. 7-13
Author(s):  
O. O. Horobets
Keyword(s):  
Big Data ◽  
Data Collection ◽  
Electronic Commerce ◽  
Business Processes ◽  
Publishing Industry ◽  
Reference Model ◽  
Book Publishing ◽  
Statistical Information ◽  
Book Publishing Industry ◽  
Practical Applications

The article’s objective is to review domestic and foreign sources related with big data, in order to determine the potentials for their practical applications at industry level, with emphasis on book publishing. The main components of big data are highlighted, which form the reference model for big data management. An all-purpose model for big data processing is constructed by use of the analyzed information sources. A brief review of Hadoop big data analysis program is carried out. Applications of big data to improve business processes are analyzed with reference to renowned international companies, Internet platforms engaged in electronic commerce, and social networks. A brief review of Ukrainian cases of successful electronic commerce is made. As regards big data applications in book publishing, reference is made to the practices of Jellybooks company. The algorithm of big data collection by use of electronic book is constructed and illustrated. It is concluded that any industry is capable to adapt the successful practices of electronic commerce leaders after leaning them. As far as book publishing is concerned, a well-organized system for on-line data collection will open up opportunities for quick production of statistical information, extension of the range of statistical data, monitoring of the current book publishing performance and prediction of its future developments.    

scholarly journals Mechanical Testing of Poly Hydroxy Butyrate Co Valerate and Natural Fiber by Varying Fiber Length

2020 ◽  
Vol 8 (4S4) ◽  
pp. 200-203
Keyword(s):  
3D Printing ◽  
Natural Fiber ◽  
Volume Fraction ◽  
Composite Plates ◽  
Weight Percentage ◽  
Practical Applications ◽  
Printing Technique ◽  
Critical Issues ◽  
The Given ◽  
3D Printing Technique

The knowledge of 3D printing material used in 3D printing technique is so abundant. Even though there are many critical issues in practical applications. This paper reports the mechanical properties of Environmental friendly Bio composites. This composite material is intended to be used as a replacement for the current 3D printing material. The composite was prepared in compression molding technique under 150 kg/cm2 pressure. The composite consists of Poly Hydroxy Butyrate co Valerate (PHBV) and Sansevieria Roxburghiana. The tensile strength of the given specimen is found to be increased by the change in the volume fraction of fibers. Initially composite plates composed of both PHBV and Sansevieria Roxburghiana are prepared with different weight percentage of PHBV and different lengths of fiber such as 20mm, 30mm, 40mm and 50mm.

Damage Identification Using a Continuously Scanning Laser Doppler Vibrometer System

2016 ◽  
Author(s):  
Da-Ming Chen ◽  
Y. F. Xu ◽  
W. D. Zhu
Keyword(s):  
Damage Identification ◽  
Excitation Frequency ◽  
Damage Index ◽  
Laser Doppler Vibrometer ◽  
Its Region ◽  
Laser Doppler ◽  
Scanning Laser ◽  
Scanning Laser Doppler Vibrometer ◽  
Baseline Information ◽  
The Difference

A continuously scanning laser Doppler vibrometer (CSLDV) system is capable of rapidly obtaining spatially dense operating deflection shapes (ODSs) by continuously sweeping a laser spot from the system over a structure surface. This paper presents a new damage identification methodology for beams that uses their ODSs under sinusoidal excitation obtained by a CSLDV system, where baseline information of associated undamaged beams is not needed. A curvature damage index (CDI) is proposed to identify damage near a region with high values of the CDI at an excitation frequency. The CDI uses the difference between curvatures of ODSs associated with ODSs that are obtained by two different CSLDV measurement methods, i.e., demodulation and polynomial methods; the former provides rapid and spatially dense ODSs of beams, and the latter provides ODSs that can be considered as those of associated undamaged beams. Phase variables are introduced to the two methods for damage identification purposes. The proposed damage identification methodology was experimentally validated on a beam with damage in the form of machined thickness reduction. The damage and its region were successfully identified in neighborhoods of prominent peaks of CDIs at different excitation frequencies.

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