scholarly journals Identifying Delay Time of Detonator for a Millisecond Blasting

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Song Zhifei ◽  
Ke Man ◽  
Liu Xiaoli

Based on wavelet transform, the blasting vibration signals are analyzed here. For millisecond blasting, the blasting effect is mostly affected by the actual delay time. Local characteristics of the analyzed signals could be highlighted by the wavelet transform. The simultaneous initiation of large explosive quantity could be avoided by the use of multistage detonators, while the vibration resistance effect could be better. For the same level of detonator segment, the larger the arranged time interval, the less the possibility of initiation at the same time, which is not conducive to the vibration resistance. Therefore, it is suggested to use high-level detonators with detonating cord or high-precision digital electronic detonators to minimize the initiation error. Furthermore, by identifying the delay time using wavelet transform, the interval delay time of different detonator segments could be obtained. Moreover, the nominal delay time, actual delay time, and interval delay time are further compared and analyzed. It is suggested that the millisecond delay series of detonators should be selected in the whole section blasting, and the segment should be jumped as much as possible, so as to increase the secondary breakage time. Detonators with longer interval delay time should be avoided to the full.

2014 ◽  
Vol 1023 ◽  
pp. 198-204
Author(s):  
Li He ◽  
Dong Wang Zhong

As a physical carrier, blasting vibration signal includes much information about blasting method, explosive charge structure and propagation medium. Based on the indoor concrete slope test with millisecond blasting and wavelet pocket analysis technology, the blasting seismic signal was analyzed in the features of energy distribution in order to control the blasting vibration hazard better. The attenuation law of the energy and the peak vibration velocity (PPV) with distance decreased were researched. The effects of delayed time interval on PPV and energy are investigated, and the paper have analyzed the weakening degree of energy and PPV of vibration signals when damping ditch exists, so was its effect on the distribution of energy. The conclusions show that: the impact is great about delayed time interval on the total energy of signals in millisecond blasting; the damping ditch made the predominant frequency for energy concentrate on the low frequency band, damping effect of the damping ditch reduced with the delay time interval increasing. When the propagation distance increased, the attenuation trend of the PPV and total energy slowed down gradually near blasting area. The PPV and energy are not necessarily meanwhile the maximum; the energy of the vibration signal is not only determined by the PPV.


2021 ◽  
Vol 11 (9) ◽  
pp. 4232
Author(s):  
Krishan Harkhoe ◽  
Guy Verschaffelt ◽  
Guy Van der Sande

Delay-based reservoir computing (RC), a neuromorphic computing technique, has gathered lots of interest, as it promises compact and high-speed RC implementations. To further boost the computing speeds, we introduce and study an RC setup based on spin-VCSELs, thereby exploiting the high polarization modulation speed inherent to these lasers. Based on numerical simulations, we benchmarked this setup against state-of-the-art delay-based RC systems and its parameter space was analyzed for optimal performance. The high modulation speed enabled us to have more virtual nodes in a shorter time interval. However, we found that at these short time scales, the delay time and feedback rate heavily influence the nonlinear dynamics. Therefore, and contrary to other laser-based RC systems, the delay time has to be optimized in order to obtain good RC performances. We achieved state-of-the-art performances on a benchmark timeseries prediction task. This spin-VCSEL-based RC system shows a ten-fold improvement in processing speed, which can further be enhanced in a straightforward way by increasing the birefringence of the VCSEL chip.


Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5286 ◽  
Author(s):  
Ugochukwu Ejike Akpudo ◽  
Jang-Wook Hur

This paper develops a novel hybrid feature learner and classifier for vibration-based fault detection and isolation (FDI) of industrial apartments. The trained model extracts high-level discriminative features from vibration signals and predicts equipment state. Against the limitations of traditional machine learning (ML)-based classifiers, the convolutional neural network (CNN) and deep neural network (DNN) are not only superior for real-time applications, but they also come with other benefits including ease-of-use, automated feature learning, and higher predictive accuracies. This study proposes a hybrid DNN and one-dimensional CNN diagnostics model (D-dCNN) which automatically extracts high-level discriminative features from vibration signals for FDI. Via Softmax averaging at the output layer, the model mitigates the limitations of the standalone classifiers. A diagnostic case study demonstrates the efficiency of the model with a significant accuracy of 92% (F1 score) and extensive comparative empirical validations.


Author(s):  
Jiqing Cong ◽  
Jianping Jing ◽  
Changmin Chen ◽  
Zezeng Dai ◽  
Jianhua Cheng

Abstract The reliability and safety of aero-engine are often the decisive factors for the safe and reliable flight of commercial aircraft. Hence, the vibration source location and fault diagnosis of aero-engine are of prime importance to detect faults and carry out fast and effective maintenance in time. However, the vibration signals collected by the sensors arranged on the casing of the aero-engine are generally the mixed signals of the main vibration sources inside the engine, and the components are extremely complicated. Therefore, the vibration source identification is a big challenge for a fault diagnosis and health management of the engine. In order to separate the key vibration sources of rotating machinery such as aero-engine, a Joint Wavelet Transform and Time Synchronous Averaging based algorithm (JWTS) is proposed in this paper. Based on the fact that the fundamental frequency and its harmonic and sub-harmonic components are generally included in the vibration spectrum of shaft fault signal of rotating machinery, wavelet transform and time synchronous averaging algorithm are combined to extract them. The algorithm completes separating the main vibration sources with three steps. First, the source number and fundamental frequency of each source are estimated using the wavelet transform. Second, every source is extracted from each observed signal by the time synchronous averaging method. Time synchronous averaging method can effectively extract a signal of cycle and harmonic rotor components and can suppress noise. Third, the optimal estimation of each source is determined according to signal’s 2-norm. Since the extracted source with a larger energy is closer to the real source, and signal’s 2-norm is a good indicator of the signal energy. Hence, the key vibration sources related to rotary speeds of the engine are obtained separately. The method is verified by synthetic mixed signals first. Three periodic signals of different frequencies are used to simulate the vibration sources of the aeroengine. The fundamental, harmonic and sub-harmonic components of them, as well as Gaussian white noise, are randomly mixed. The results show that the JWTS algorithm can estimate the number of the main sources and can extract each source effectively. Then the method is demonstrated using vibration signals of a real aero-engine. The results indicate that the proposed JWTS method has extracted and located the main sources within the aero-engine, including sources from the low-pressure rotor, high-pressure rotor, combustion chamber and accessory. Therefore, the proposed method provides a new fault diagnosis technology for rotating machinery, especially for a real aero-engine.


2021 ◽  
Vol 16 (1(21)) ◽  
pp. 22-31
Author(s):  
David Bidzinashvili

The new Corona-virus and the contagious disease which it causes, the so called COVID 19, put forward the serious challenges for many countries all over the world and for Georgia among them. Almost the whole world is facing very serious obstacles on the international and national levels. Too many problems emerged in the world countries. To resist against the new disease has become the main priority for each country. The global processes caused by the pandemics have influenced the audit service as well. The uncertainty and unpredictability caused the new risks of deficiencies and activated already existed ones in the new environment. The situation became more complicated due to the fact that it can happen that the auditors do not consider the mentioned risks in the process of planning for audits or the risks may be considered mistakenly. The firms and other economical institutions in which the audit is carried out are obliged to adopt the new rules and changing environments in which their businesses function; they should change the rules of fulfilling the operation, preparing the financial accounts, the processes of their representing the information processes, safety of information shown in the financial accounts, the rules of their preparing; they also evaluate the possibilities of keeping on their activities in the nearest future. The qualified performing of the audit implies the basical elemenst which helps to create such environment where the possibility of the high level audit will be at the maximum. Implementing the quality control implies that such system will include two stages; each of them is directed towards providing the audit processes according the international standards There are several types of the quality improvement system. In all of them the main variable value represents the amount of costs for the proper system. All countries choose the system which provides benefits taking the costs into consideration. There are four main stages in the process of implementation the system which will ensure the high quality audit. Here are four main stages shown in the process of implementation:  The first stage: to carry out diagnostic observation;  The second stage: stating the view;  The third sage: working out the system;  The fourth stage: implementation of the system. The firms and other economical institutions where the audit is carried out are obliged to be reliable with their activities in the changing situation in which their businesses function. The subjects change the rules of carrying out the usual operations, change the open information given in the financial accounts, and estimate the possibilities of maintaining the existing possibilities for the nearest future. It is important to revise some standards out of Audit International Standards and to make them fit for revealing and assessing the risks of essential mistakes and discrepencies. The controlled variation of the standard regulates such issues as the newly corrected risks caused by influences of COVID-19 pandemic on the planned approaches to the audit and also, evaluation of the risks already defined and making changes in them taking into consideration the influence of the errors in the risk evaluations and influence made upon the planned evaluations and audits the changes of which will influence the evaluations of the risks in the inner control of the subject on the previously made imagination of the control environment, in order to define the measures to be taken in order to change the reactions to the mistakes using different measures in order to reach the trustful mechanisms to rely on. International standards of audit– answering to the assessed risks, the checked variation of the standard implies that it maybecome necessary to change the measures of reaction to the changes in the circumstances in order to obtain enough reliable measures and activities to control the situation by means of enough auditory evidences. The auditor has responsibilities to take into consideration that largening the deadlines will cause growth of the period and the risks of the dates of events which will happen in the time interval between accountability date and the date of the conclusion made by audit, the audit is also responsible for any event taking place later in relation to the Covid-19 situation. He is responsible also for evaluation of the fact about financial information. The enterprise functioning within nowadays complex environment taking into consideration the situation of COVID 19, should consider such priority issues as the uncertainty accompanying the Covid situation, related covenants, and others which accompany the pandemic period, among them the region, the financial state of customers and dealers, liquidating and paying capacity. During the process of the risk assessments it should considered that Covid 19 pandemic greatly influenced the global economics and the separate branches such as hotels business, retail sail, tourism and others. As a result of pandemic, it is possible that the number of audit considerations and thee circumstances can modify them which can be conditioned by different circumstances and the audit will state if there are incorrectable improper conditioned due to the circumstances. The audit will make it certain there are unimprovable mistakes which apart and together are essential for the financial accountability and the auditor will conclude that they cannot acquire the proper conditioned which apart or together could be essential financial accounts or the audit will conclude that they are not able to the essential accountability. Important researches were led to assess the appeared situation and it was concluded that the COVID 19 pandemic had influenced the financial situation which showed that the specific actions and procedures became complicated.


2021 ◽  
Author(s):  
Jose R. Huerta-Rosales ◽  
Martin Valtierra-Rodriguez ◽  
Juan P. Amezquita-Sanchez ◽  
David Granados-Lieberman

2010 ◽  
Vol 439-440 ◽  
pp. 1037-1041 ◽  
Author(s):  
Yan Jue Gong ◽  
Zhao Fu ◽  
Hui Yu Xiang ◽  
Li Zhang ◽  
Chun Ling Meng

On the basis of wavelet denoising and its better time-frequency characteristic, this paper presents an effective vibration signal denoising method for food refrigerant air compressor. The solution of eliminating strong noise is investigated with the combination of soft threshold and exponential lipschitza. The good denoising results show that the presented method is effective for improving the signal noise ratio and builds the good foundation for further extraction of the vibration signals.


2019 ◽  
Vol 53 (1-2) ◽  
pp. 3-17
Author(s):  
A Anandh ◽  
K Mala ◽  
R Suresh Babu

Nowadays, user expects image retrieval systems using a large database as an active research area for the investigators. Generally, content-based image retrieval system retrieves the images based on the low-level features, high-level features, or the combination of both. Content-based image retrieval results can be improved by considering various features like directionality, contrast, coarseness, busyness, local binary pattern, and local tetra pattern with modified binary wavelet transform. In this research work, appropriate features are identified, applied and results are validated against existing systems. Modified binary wavelet transform is a modified form of binary wavelet transform and this methodology produced more similar retrieval images. The proposed system also combines the interactive feedback to retrieve the user expected results by addressing the issues of semantic gap. The quantitative evaluations such as average retrieval rate, false image acceptation ratio, and false image rejection ratio are evaluated to ensure the user expected results of the system. In addition to that, precision and recall are evaluated from the proposed system against the existing system results. When compared with the existing content-based image retrieval methods, the proposed approach provides better retrieval accuracy.


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