Article Article types Articles commonly fall into one of three main categories:Full-length articles,Review articles and Short communications.Full-length articles are original,unpublished primary research.Extensions of...Article Article types Articles commonly fall into one of three main categories:Full-length articles,Review articles and Short communications.Full-length articles are original,unpublished primary research.Extensions of work that has been published previously in short form such as a Communication are usually acceptable.展开更多
Introduction Types of paper Contributions falling into the following categories will be considered for publication: Original research papers, reviews, Research Notes, Short Communication, New technologies, News and Vi...Introduction Types of paper Contributions falling into the following categories will be considered for publication: Original research papers, reviews, Research Notes, Short Communication, New technologies, News and Views, Commentary on significant events and topics in global horticultural fields with international interests.展开更多
INTRODUCTION Types of paper Contributions falling into the following categories will be considered for publication:Original research papers,reviews and short communications.Please ensure that you select the appropriat...INTRODUCTION Types of paper Contributions falling into the following categories will be considered for publication:Original research papers,reviews and short communications.Please ensure that you select the appropriate article type from the list of options when making your submission.Authors contributing to special issues should ensure that they select the special issue article type from this list.展开更多
Introduction Types of paper Contributions falling into the following categories will be considered for publication:Original research papers,Reviews,Short communication.Please ensure that you select the appropriate art...Introduction Types of paper Contributions falling into the following categories will be considered for publication:Original research papers,Reviews,Short communication.Please ensure that you select the appropriate article type from the list of options when making your submission.Authors contributing to special issues should ensure that they select the special issue article type from this list.展开更多
Despite the success of guided wave ultrasonic inspection for internal defect detection in steel pipes,its application on polyethylene(PE)pipe remains relatively unexplored.The growth of internal cracks in PE pipe seve...Despite the success of guided wave ultrasonic inspection for internal defect detection in steel pipes,its application on polyethylene(PE)pipe remains relatively unexplored.The growth of internal cracks in PE pipe severely affects its pressure-holding capacity,hence the early detection of internal cracks is crucial for effective pipeline maintenance strategies.This study extends the scope of guided wave-based ultrasonic testing to detect the growth of internal cracks in a natural gas distribution PE pipe.Laboratory experiments and a finite element model were planned to study the wave-crack interaction at different stages of axially oriented internal crack growth with a piezoceramic transducer-based setup arranged in a pitch-catch configuration.Mode dispersion analysis supplemented with preliminary experiments was performed to isolate the optimal inspection frequency,leading to the selection of the T(0,1)mode at 50-kHz for the investigation.A transmission index based on the energy of the T(0,1)mode was developed to trace the extent of simulated crack growth.The findings revealed an inverse linear correlation between the transmission index and the crack depth for crack growth beyond 20%crack depth.展开更多
The present work proposed a new method for the modeling by the finite element method of the acoustic propagation problems in infinite axisymmetric cylindrical guides lined with locally reacting absorbent materials wit...The present work proposed a new method for the modeling by the finite element method of the acoustic propagation problems in infinite axisymmetric cylindrical guides lined with locally reacting absorbent materials without flow. The method deals with the development of an efficient transparent boundary condition based on DtN operators. The method developed in this study is successfully applied to a straight axisymmetric lined guide by imposing a mode on one of the artificial boundaries of the truncated guide. The results are in good agreement with analytical solutions. Applying the method for a non-uniform axisymmetric lined guide which is a complex case, proved its effectiveness and the results compared to those of PML layers are in very good agreement.展开更多
Automated Guided Vehicles(AGVs)have been introduced into various applications,such as automated warehouse systems,flexible manufacturing systems,and container terminal systems.However,few publications have outlined pr...Automated Guided Vehicles(AGVs)have been introduced into various applications,such as automated warehouse systems,flexible manufacturing systems,and container terminal systems.However,few publications have outlined problems in need of attention in AGV applications comprehensively.In this paper,several key issues and essential models are presented.First,the advantages and disadvantages of centralized and decentralized AGVs systems were compared;second,warehouse layout and operation optimization were introduced,including some omitted areas,such as AGVs fleet size and electrical energy management;third,AGVs scheduling algorithms in chessboardlike environments were analyzed;fourth,the classical route-planning algorithms for single AGV and multiple AGVs were presented,and some Artificial Intelligence(AI)-based decision-making algorithms were reviewed.Furthermore,a novel idea for accelerating route planning by combining Reinforcement Learning(RL)andDijkstra’s algorithm was presented,and a novel idea of the multi-AGV route-planning method of combining dynamic programming and Monte-Carlo tree search was proposed to reduce the energy cost of systems.展开更多
Article■ Article types Articles commonly fall into one of three main categories: Fulllength articles, Review articles and Short communications.Full-length articles are original, unpublished primary research. Extensio...Article■ Article types Articles commonly fall into one of three main categories: Fulllength articles, Review articles and Short communications.Full-length articles are original, unpublished primary research. Extensions of work that has been published previously in short form such as a Communication are usually acceptable.Short communications must contain original and highly significant work whose high novelty warrants rapid publication.展开更多
Article Article types Articles commonly fall into one of three main categories:Fulllength articles,Review articles and Short communications.Full-length articles are original,unpublished primary research.Extensions of ...Article Article types Articles commonly fall into one of three main categories:Fulllength articles,Review articles and Short communications.Full-length articles are original,unpublished primary research.Extensions of work that has been published previously in short form such as a Communication are usually acceptable.Short communications must contain original and highly significant work whose high novelty warrants rapid publication.展开更多
Background: The diagnosis of prostate cancer (PCa) relies on clinical assessment with digital rectal examination, serum PSA and histological examination. Limitations in our technical facilities, high financial cost of...Background: The diagnosis of prostate cancer (PCa) relies on clinical assessment with digital rectal examination, serum PSA and histological examination. Limitations in our technical facilities, high financial cost of ultrasound-guided biopsy often prevent us from implementing the guidelines on the practice of prostate biopsy. Methods: We conducted a retrospective and cross-sectional descriptive study comparing digital-guided and ultrasound-guided transrectal prostate biopsy of 400 patients over a period of 12 years in the Yaounde Central Hospital. We reviewed files of patients who underwent digital and ultrasound guided biopsy procedures. Data was analyzed using EPI info 7.0. Parametric variables were reported as means and standard deviations and percentages and counts were used to report categorical variables. Results: Out of the 400 patients, 292 digital-guided transrectal biopsies (73%) and 108 ultrasound-guided transrectal biopsies (27%) were performed in patients who were suspected of having prostate cancer (PCa). Patients were aged between 39 to 90 years. Both procedures were effective in identifying prostate cancer. Gleason score between 2 to 10 detected prostate adenocarcinoma for 301 patients (75.2%). The complications included anal pain, rectal bleeding, hematuria and urinary tract infections, with an occurrence rate similar for both ultrasound-guided (2.25%) and digitally-guided techniques (2.5%). Seven patients (1.75%) required hospitalization for management of complications. The mortality rate was null. Conclusion: Both techniques are effective in detecting PCa with the similar complication rates. Digital-guided trans-rectal prostate biopsy still has its place in a resource-limited setting like ours.展开更多
Article ■ Article types Articles commonly fall into one of three main categories: Full-length articles, Review articles and Short communications.Full-length articles are original, unpublished primary research. Extens...Article ■ Article types Articles commonly fall into one of three main categories: Full-length articles, Review articles and Short communications.Full-length articles are original, unpublished primary research. Extensions of work that has been published previously in short form such as a Communication are usually acceptable.展开更多
INTRODUCTION Types of paper Contributions falling into the following categories will be considered for publication:Original research papers,reviews and short communications.Please ensure that you select the appropriat...INTRODUCTION Types of paper Contributions falling into the following categories will be considered for publication:Original research papers,reviews and short communications.Please ensure that you select the appropriate article type from the list of options when making your submission.Authors contributing to special issues should ensure that they select the special issue article type from this list.展开更多
INTRODUCTION Types of paper Contributions falling into the following categories will be considered for publication:Original research papers,reviews and short communications.Please ensure that you select the appropriat...INTRODUCTION Types of paper Contributions falling into the following categories will be considered for publication:Original research papers,reviews and short communications.Please ensure that you select the appropriate article type from the list of options when making your submission.Authors contributing to special issues should ensure that they select the special issue article type from this list.展开更多
Magnetic reconnection is well known as an efficient mechanism for transferring magnetic energy into plasma energy.However,how the energy conversion and partition between different species is influenced by the shear an...Magnetic reconnection is well known as an efficient mechanism for transferring magnetic energy into plasma energy.However,how the energy conversion and partition between different species is influenced by the shear angle of the reconnecting magnetic component(i.e.,the guide field strength)is not well understood.Using 2.5-dimensional particle-in-cell simulations,we investigated the energy conversion in reconnection with different guide fields.We found that the overall energy conversion first decreases steeply and then increases slowly when the guide field increases fromB_(g)=0 toB_(g)=4.The increase in energy conversion in the large guide field regime is due to the electron energy gain through the perpendicular channelJ_(⊥)·E_(⊥).The overall energy conversion is predominantly contributed byJ_(⊥)·E_(⊥) rather thanJ||E||.We further find that energy conversion mainly occurs within the reconnection front and the flux pileup region.However,the contribution from the fore reconnection front becomes important in large guide field regimes(3<B_(g)≤4)because of the enhanced electron energy gain.展开更多
Introduction Types of paper Contributions falling into the following categories will be considered for publication:Original research papers,Reviews,Short communication.Please ensure that you select the appropriate art...Introduction Types of paper Contributions falling into the following categories will be considered for publication:Original research papers,Reviews,Short communication.Please ensure that you select the appropriate article type from the list of options when making your submission.Authors contributing to special issues should ensure that they select the special issue article type from this list.展开更多
Deep convolution neural networks are going deeper and deeper.How-ever,the complexity of models is prone to overfitting in training.Dropout,one of the crucial tricks,prevents units from co-adapting too much by randomly...Deep convolution neural networks are going deeper and deeper.How-ever,the complexity of models is prone to overfitting in training.Dropout,one of the crucial tricks,prevents units from co-adapting too much by randomly drop-ping neurons during training.It effectively improves the performance of deep net-works but ignores the importance of the differences between neurons.To optimize this issue,this paper presents a new dropout method called guided dropout,which selects the neurons to switch off according to the differences between the convo-lution kernel and preserves the informative neurons.It uses an unsupervised clus-tering algorithm to cluster similar neurons in each hidden layer,and dropout uses a certain probability within each cluster.Thereby this would preserve the hidden layer neurons with different roles while maintaining the model’s scarcity and gen-eralization,which effectively improves the role of the hidden layer neurons in learning the features.We evaluated our approach compared with two standard dropout networks on three well-established public object detection datasets.Experimental results on multiple datasets show that the method proposed in this paper has been improved on false positives,precision-recall curve and average precision without increasing the amount of computation.It can be seen that the increased performance of guided dropout is thanks to shallow learning in the net-works.The concept of guided dropout would be beneficial to the other vision tasks.展开更多
A rockbolt acting in the rock mass is subjected to the combined action of the pull-out load and confining pressure, and the bond quality of the rockbolt directly affects the stability of the roadway and cavern. Theref...A rockbolt acting in the rock mass is subjected to the combined action of the pull-out load and confining pressure, and the bond quality of the rockbolt directly affects the stability of the roadway and cavern. Therefore, in this study, confining pressure and pull-out load are applied to grouted rockbolt systems with bond defects by a numerical simulation method, and the rockbolt is detected by ultrasonic guided waves to study the propagation law of ultrasonic guided waves in defective rockbolt systems and the bond quality of rockbolts under the combined action of pull-out load and confining pressure. The numerical simulation results show that the length and location of bond defects can be detected by ultrasonic guided waves under the combined action of pull-out load and confining pressure. Under no pull-out load, with increasing confining pressure, the low-frequency part of the guided wave frequency in the rockbolt increases, the high-frequency part decreases, the weakening effect of the confining pressure on the guided wave propagation law increases, and the bond quality of the rockbolt increases. The existence of defects cannot change the strengthening effect of the confining pressure on the guided wave propagation law under the same pull-out load or the weakening effect of the pull-out load on the guided wave propagation law under the same confining pressure.展开更多
文摘Article Article types Articles commonly fall into one of three main categories:Full-length articles,Review articles and Short communications.Full-length articles are original,unpublished primary research.Extensions of work that has been published previously in short form such as a Communication are usually acceptable.
文摘Introduction Types of paper Contributions falling into the following categories will be considered for publication: Original research papers, reviews, Research Notes, Short Communication, New technologies, News and Views, Commentary on significant events and topics in global horticultural fields with international interests.
文摘INTRODUCTION Types of paper Contributions falling into the following categories will be considered for publication:Original research papers,reviews and short communications.Please ensure that you select the appropriate article type from the list of options when making your submission.Authors contributing to special issues should ensure that they select the special issue article type from this list.
文摘Introduction Types of paper Contributions falling into the following categories will be considered for publication:Original research papers,Reviews,Short communication.Please ensure that you select the appropriate article type from the list of options when making your submission.Authors contributing to special issues should ensure that they select the special issue article type from this list.
基金the financial support provided by USDOT Pipeline and Hazardous Materials Safety Administration (PHMSA)through the Competitive Academic Agreement Program (CAAP)。
文摘Despite the success of guided wave ultrasonic inspection for internal defect detection in steel pipes,its application on polyethylene(PE)pipe remains relatively unexplored.The growth of internal cracks in PE pipe severely affects its pressure-holding capacity,hence the early detection of internal cracks is crucial for effective pipeline maintenance strategies.This study extends the scope of guided wave-based ultrasonic testing to detect the growth of internal cracks in a natural gas distribution PE pipe.Laboratory experiments and a finite element model were planned to study the wave-crack interaction at different stages of axially oriented internal crack growth with a piezoceramic transducer-based setup arranged in a pitch-catch configuration.Mode dispersion analysis supplemented with preliminary experiments was performed to isolate the optimal inspection frequency,leading to the selection of the T(0,1)mode at 50-kHz for the investigation.A transmission index based on the energy of the T(0,1)mode was developed to trace the extent of simulated crack growth.The findings revealed an inverse linear correlation between the transmission index and the crack depth for crack growth beyond 20%crack depth.
文摘The present work proposed a new method for the modeling by the finite element method of the acoustic propagation problems in infinite axisymmetric cylindrical guides lined with locally reacting absorbent materials without flow. The method deals with the development of an efficient transparent boundary condition based on DtN operators. The method developed in this study is successfully applied to a straight axisymmetric lined guide by imposing a mode on one of the artificial boundaries of the truncated guide. The results are in good agreement with analytical solutions. Applying the method for a non-uniform axisymmetric lined guide which is a complex case, proved its effectiveness and the results compared to those of PML layers are in very good agreement.
文摘Automated Guided Vehicles(AGVs)have been introduced into various applications,such as automated warehouse systems,flexible manufacturing systems,and container terminal systems.However,few publications have outlined problems in need of attention in AGV applications comprehensively.In this paper,several key issues and essential models are presented.First,the advantages and disadvantages of centralized and decentralized AGVs systems were compared;second,warehouse layout and operation optimization were introduced,including some omitted areas,such as AGVs fleet size and electrical energy management;third,AGVs scheduling algorithms in chessboardlike environments were analyzed;fourth,the classical route-planning algorithms for single AGV and multiple AGVs were presented,and some Artificial Intelligence(AI)-based decision-making algorithms were reviewed.Furthermore,a novel idea for accelerating route planning by combining Reinforcement Learning(RL)andDijkstra’s algorithm was presented,and a novel idea of the multi-AGV route-planning method of combining dynamic programming and Monte-Carlo tree search was proposed to reduce the energy cost of systems.
文摘Article■ Article types Articles commonly fall into one of three main categories: Fulllength articles, Review articles and Short communications.Full-length articles are original, unpublished primary research. Extensions of work that has been published previously in short form such as a Communication are usually acceptable.Short communications must contain original and highly significant work whose high novelty warrants rapid publication.
文摘Article Article types Articles commonly fall into one of three main categories:Fulllength articles,Review articles and Short communications.Full-length articles are original,unpublished primary research.Extensions of work that has been published previously in short form such as a Communication are usually acceptable.Short communications must contain original and highly significant work whose high novelty warrants rapid publication.
文摘Background: The diagnosis of prostate cancer (PCa) relies on clinical assessment with digital rectal examination, serum PSA and histological examination. Limitations in our technical facilities, high financial cost of ultrasound-guided biopsy often prevent us from implementing the guidelines on the practice of prostate biopsy. Methods: We conducted a retrospective and cross-sectional descriptive study comparing digital-guided and ultrasound-guided transrectal prostate biopsy of 400 patients over a period of 12 years in the Yaounde Central Hospital. We reviewed files of patients who underwent digital and ultrasound guided biopsy procedures. Data was analyzed using EPI info 7.0. Parametric variables were reported as means and standard deviations and percentages and counts were used to report categorical variables. Results: Out of the 400 patients, 292 digital-guided transrectal biopsies (73%) and 108 ultrasound-guided transrectal biopsies (27%) were performed in patients who were suspected of having prostate cancer (PCa). Patients were aged between 39 to 90 years. Both procedures were effective in identifying prostate cancer. Gleason score between 2 to 10 detected prostate adenocarcinoma for 301 patients (75.2%). The complications included anal pain, rectal bleeding, hematuria and urinary tract infections, with an occurrence rate similar for both ultrasound-guided (2.25%) and digitally-guided techniques (2.5%). Seven patients (1.75%) required hospitalization for management of complications. The mortality rate was null. Conclusion: Both techniques are effective in detecting PCa with the similar complication rates. Digital-guided trans-rectal prostate biopsy still has its place in a resource-limited setting like ours.
文摘Article ■ Article types Articles commonly fall into one of three main categories: Full-length articles, Review articles and Short communications.Full-length articles are original, unpublished primary research. Extensions of work that has been published previously in short form such as a Communication are usually acceptable.
文摘INTRODUCTION Types of paper Contributions falling into the following categories will be considered for publication:Original research papers,reviews and short communications.Please ensure that you select the appropriate article type from the list of options when making your submission.Authors contributing to special issues should ensure that they select the special issue article type from this list.
文摘INTRODUCTION Types of paper Contributions falling into the following categories will be considered for publication:Original research papers,reviews and short communications.Please ensure that you select the appropriate article type from the list of options when making your submission.Authors contributing to special issues should ensure that they select the special issue article type from this list.
基金supported by the National Natural Science Foundation of China (NSFC) under Grants 42074197, 42130211, 42104156, and 41774154the China Postdoctoral Science Foundation under Grant 2021M691395
文摘Magnetic reconnection is well known as an efficient mechanism for transferring magnetic energy into plasma energy.However,how the energy conversion and partition between different species is influenced by the shear angle of the reconnecting magnetic component(i.e.,the guide field strength)is not well understood.Using 2.5-dimensional particle-in-cell simulations,we investigated the energy conversion in reconnection with different guide fields.We found that the overall energy conversion first decreases steeply and then increases slowly when the guide field increases fromB_(g)=0 toB_(g)=4.The increase in energy conversion in the large guide field regime is due to the electron energy gain through the perpendicular channelJ_(⊥)·E_(⊥).The overall energy conversion is predominantly contributed byJ_(⊥)·E_(⊥) rather thanJ||E||.We further find that energy conversion mainly occurs within the reconnection front and the flux pileup region.However,the contribution from the fore reconnection front becomes important in large guide field regimes(3<B_(g)≤4)because of the enhanced electron energy gain.
文摘Introduction Types of paper Contributions falling into the following categories will be considered for publication:Original research papers,Reviews,Short communication.Please ensure that you select the appropriate article type from the list of options when making your submission.Authors contributing to special issues should ensure that they select the special issue article type from this list.
基金This work is supported by the National Natural Science Funds of China(Project No.U19B2036).
文摘Deep convolution neural networks are going deeper and deeper.How-ever,the complexity of models is prone to overfitting in training.Dropout,one of the crucial tricks,prevents units from co-adapting too much by randomly drop-ping neurons during training.It effectively improves the performance of deep net-works but ignores the importance of the differences between neurons.To optimize this issue,this paper presents a new dropout method called guided dropout,which selects the neurons to switch off according to the differences between the convo-lution kernel and preserves the informative neurons.It uses an unsupervised clus-tering algorithm to cluster similar neurons in each hidden layer,and dropout uses a certain probability within each cluster.Thereby this would preserve the hidden layer neurons with different roles while maintaining the model’s scarcity and gen-eralization,which effectively improves the role of the hidden layer neurons in learning the features.We evaluated our approach compared with two standard dropout networks on three well-established public object detection datasets.Experimental results on multiple datasets show that the method proposed in this paper has been improved on false positives,precision-recall curve and average precision without increasing the amount of computation.It can be seen that the increased performance of guided dropout is thanks to shallow learning in the net-works.The concept of guided dropout would be beneficial to the other vision tasks.
文摘A rockbolt acting in the rock mass is subjected to the combined action of the pull-out load and confining pressure, and the bond quality of the rockbolt directly affects the stability of the roadway and cavern. Therefore, in this study, confining pressure and pull-out load are applied to grouted rockbolt systems with bond defects by a numerical simulation method, and the rockbolt is detected by ultrasonic guided waves to study the propagation law of ultrasonic guided waves in defective rockbolt systems and the bond quality of rockbolts under the combined action of pull-out load and confining pressure. The numerical simulation results show that the length and location of bond defects can be detected by ultrasonic guided waves under the combined action of pull-out load and confining pressure. Under no pull-out load, with increasing confining pressure, the low-frequency part of the guided wave frequency in the rockbolt increases, the high-frequency part decreases, the weakening effect of the confining pressure on the guided wave propagation law increases, and the bond quality of the rockbolt increases. The existence of defects cannot change the strengthening effect of the confining pressure on the guided wave propagation law under the same pull-out load or the weakening effect of the pull-out load on the guided wave propagation law under the same confining pressure.