In the framework of vigorous promotion of low-carbon power system growth as well as economic globalization,multi-resource penetration in active distribution networks has been advancing fiercely.In particular,distribut...In the framework of vigorous promotion of low-carbon power system growth as well as economic globalization,multi-resource penetration in active distribution networks has been advancing fiercely.In particular,distributed generation(DG)based on renewable energy is critical for active distribution network operation enhancement.To comprehensively analyze the accessing impact of DG in distribution networks from various parts,this paper establishes an optimal DG location and sizing planning model based on active power losses,voltage profile,pollution emissions,and the economics of DG costs as well as meteorological conditions.Subsequently,multiobjective particle swarm optimization(MOPSO)is applied to obtain the optimal Pareto front.Besides,for the sake of avoiding the influence of the subjective setting of the weight coefficient,the decisionmethod based on amodified ideal point is applied to execute a Pareto front decision.Finally,simulation tests based on IEEE33 and IEEE69 nodes are designed.The experimental results show thatMOPSO can achieve wider and more uniformPareto front distribution.In the IEEE33 node test system,power loss,and voltage deviation decreased by 52.23%,and 38.89%,respectively,while taking the economy into account.In the IEEE69 test system,the three indexes decreased by 19.67%,and 58.96%,respectively.展开更多
In convolutional neural networks,pooling methods are used to reduce both the size of the data and the number of parameters after the convolution of the models.These methods reduce the computational amount of convoluti...In convolutional neural networks,pooling methods are used to reduce both the size of the data and the number of parameters after the convolution of the models.These methods reduce the computational amount of convolutional neural networks,making the neural network more efficient.Maximum pooling,average pooling,and minimum pooling methods are generally used in convolutional neural networks.However,these pooling methods are not suitable for all datasets used in neural network applications.In this study,a new pooling approach to the literature is proposed to increase the efficiency and success rates of convolutional neural networks.This method,which we call MAM(Maximum Average Minimum)pooling,is more interactive than other traditional maximum pooling,average pooling,and minimum pooling methods and reduces data loss by calculating the more appropriate pixel value.The proposed MAM pooling method increases the performance of the neural network by calculating the optimal value during the training of convolutional neural networks.To determine the success accuracy of the proposed MAM pooling method and compare it with other traditional pooling methods,training was carried out on the LeNet-5 model using CIFAR-10,CIFAR-100,and MNIST datasets.According to the results obtained,the proposed MAM pooling method performed better than the maximum pooling,average pooling,and minimum pooling methods in all pool sizes on three different datasets.展开更多
Pooling,unpooling/specialization,and discretionary task completion are typical operational strategies in queueing systems that arise in healthcare,call centers,and online sales.These strategies may have advantages and...Pooling,unpooling/specialization,and discretionary task completion are typical operational strategies in queueing systems that arise in healthcare,call centers,and online sales.These strategies may have advantages and disadvantages in different operational environments.This paper uses the M/M/1 and M/M/2 queues to study the impact of pooling,specialization,and discretionary task completion on the average queue length.Closed-form solutions for the average M/M/2 queue length are derived.Computational examples illustrate how the average queue length changes with the strength of pooling,specialization,and discretionary task completion.Finally,several conjectures are made in the paper.展开更多
The state of in situ stress is a crucial parameter in subsurface engineering,especially for critical projects like nuclear waste repository.As one of the two ISRM suggested methods,the overcoring(OC)method is widely u...The state of in situ stress is a crucial parameter in subsurface engineering,especially for critical projects like nuclear waste repository.As one of the two ISRM suggested methods,the overcoring(OC)method is widely used to estimate the full stress tensors in rocks by independent regression analysis of the data from each OC test.However,such customary independent analysis of individual OC tests,known as no pooling,is liable to yield unreliable test-specific stress estimates due to various uncertainty sources involved in the OC method.To address this problem,a practical and no-cost solution is considered by incorporating into OC data analysis additional information implied within adjacent OC tests,which are usually available in OC measurement campaigns.Hence,this paper presents a Bayesian partial pooling(hierarchical)model for combined analysis of adjacent OC tests.We performed five case studies using OC test data made at a nuclear waste repository research site of Sweden.The results demonstrate that partial pooling of adjacent OC tests indeed allows borrowing of information across adjacent tests,and yields improved stress tensor estimates with reduced uncertainties simultaneously for all individual tests than they are independently analysed as no pooling,particularly for those unreliable no pooling stress estimates.A further model comparison shows that the partial pooling model also gives better predictive performance,and thus confirms that the information borrowed across adjacent OC tests is relevant and effective.展开更多
In order to enhance the performance of the CNN-based segmentation models for bone metastases, this study proposes a segmentation method that integrates dual-pooling, DAC, and RMP modules. The network consists of disti...In order to enhance the performance of the CNN-based segmentation models for bone metastases, this study proposes a segmentation method that integrates dual-pooling, DAC, and RMP modules. The network consists of distinct feature encoding and decoding stages, with dual-pooling modules employed in encoding stages to maintain the background information needed for bone scintigrams diagnosis. Both the DAC and RMP modules are utilized in the bottleneck layer to address the multi-scale problem of metastatic lesions. Experimental evaluations on 306 clinical SPECT data have demonstrated that the proposed method showcases a substantial improvement in both DSC and Recall scores by 3.28% and 6.55% compared the baseline. Exhaustive case studies illustrate the superiority of the methodology.展开更多
Liver transplantation(LT)provides a life-saving option for cirrhotic patients with complications and hepatocellular carcinoma.Despite the increasing number of liver transplants performed each year,the number of LT can...Liver transplantation(LT)provides a life-saving option for cirrhotic patients with complications and hepatocellular carcinoma.Despite the increasing number of liver transplants performed each year,the number of LT candidates on the waitlist remains unchanged due to an imbalance between donor organ supply and the demand which increases the waitlist time and mortality.Living donor liver transplant had a great role in increasing the donor pool and shortened waitlist time for LT candidates.Nevertheless,further strategies can be implemented to increase the pool of potential donors in deceased donor LT,such as reducing the rate of organ discards.Utilizing hepatitis C virus(HCV)seropositive liver grafts is one of the expanded donor organ criteria.A yearly increase of hundreds of transplants is anticipated as a result of maximizing the utilization of HCV-positive organs for HCV-negative recipients.Direct-acting antiviral therapy's efficacy has revolutionized the treatment of HCV infection and the use of HCV-seropositive donors in transplantation.The American Society of Transplantation advises against performing transplants from HCV-infected liver donors(D+)into HCV-negative recipient(R-)unless under Institutional Review Board-approved study rules and with full informed consent of the knowledge gaps associated with such transplants.Proper selection of patients to be transplanted with HCV-infected grafts and confirming their access to direct-acting antivirals if needed is im-portant.National and international consensuses are needed to regulate this process to ensure the maximum benefit and the least adverse events.展开更多
Recently, the critical chain study has become a hot issue in the project management research field. The construction of the critical chain with multi-resource constraints is a new research subject. According to the sy...Recently, the critical chain study has become a hot issue in the project management research field. The construction of the critical chain with multi-resource constraints is a new research subject. According to the system analysis theory and project portfolio theory, this paper discusses the creation of project portfolios based on the similarity principle and gives the definition of priority in multi-resource allocation based on quantitative analysis. A model with multi-resource constraints, which can be applied to the critical chain construction of the A-bid section in the South-to-North Water Diversion Project, was proposed. Contrast analysis with the comprehensive treatment construction method and aggressive treatment construction method was carried out. This paper also makes suggestions for further research directions and subjects, which will be useful in improving the theories in relevant research fields.展开更多
This paper addresses multi-resource fair allocation: a fundamental research topic in cloud computing. To improve resource utilization under well-studied fairness constraints, we propose a new allocation mechanism call...This paper addresses multi-resource fair allocation: a fundamental research topic in cloud computing. To improve resource utilization under well-studied fairness constraints, we propose a new allocation mechanism called Dominant Resource with Bottlenecked Fairness(DRBF), which generalizes Bottleneck-aware Allocation(BAA) to the settings of Dominant Resource Fairness(DRF). We classify users into different queues by their dominant resources. The goals are to ensure that users in the same queue receive allocations in proportion to their fair shares while users in different queues receive allocations that maximize resource utilization subject to well-studied fairness properties such as those in DRF. Under DRBF, no user 1) is worse off sharing resources than dividing resources equally among all users; 2) prefers the allocation of another user; 3) can improve their own allocation without reducing other users' allocations; and(4) can benefit by misreporting their resource demands. Experiments demonstrate that the proposed allocation policy performs better in terms of high resource utilization than does DRF.展开更多
The six-generation(6G)wireless network is expected to satisfy the requirements of ubiquitous connectivity and intelligent endogenous.Terrestrialsatellite networks(TSN)enable seamless coverage for terrestrial users in ...The six-generation(6G)wireless network is expected to satisfy the requirements of ubiquitous connectivity and intelligent endogenous.Terrestrialsatellite networks(TSN)enable seamless coverage for terrestrial users in a wide area,making it very promising in 6G.As data traffic in TSNs surges,the integrated management for caching,computing,and communication(3C)has attracted much research attention.In this paper,we investigate the multi-resource management in the uplink and downlink transmission of TSN,respectively.In particularly,we aim to guarantee both throughput fairness and data security in the uplink transmission of TSN.Considering the intermittent communication of the satellite,we introduce two kinds of relays,i.e.,terrestrial relays(TRs)and aerial relays(ARs)to improve the system throughput performance in the downlink transmission of TSN.Finally,we study a specific case of TSN with the uplink and downlink transmission,and the corresponding simulation results validate the effectiveness of our proposed schemes.展开更多
We use the phase field method to track the gas-liquid interface based on the gas-liquid two-phase flow in the pool boiling process,and study the bubble nucleation,growth,deformation,departure and other dynamic behavio...We use the phase field method to track the gas-liquid interface based on the gas-liquid two-phase flow in the pool boiling process,and study the bubble nucleation,growth,deformation,departure and other dynamic behaviors on the heating surface under microgravity.By simulating the correlation between liquid undercooling and bubble dynamics,we find that the bubble growth time increases with the increase of liquid undercooling,but the effect of liquid undercooling on bubble height is not significant.Meanwhile,the gas-liquid-solid three-phase contact angle and the gravity level will also have an effect on the bubble growth time and bubble height.With the increase of the contact angle,the bubble growth time and bubble height when the bubble departs also increase.While the effect of gravity level is on the contrary,the smaller the gravity level is,the larger the bubble height and bubble growth time when the bubble separates.展开更多
As a dynamic ex situ conservation strategy,a clonal seed orchard was started in a nursery in Pomaio(POM)in central Italy in 1993 for an assisted migration experiment of Abies nebrodensis(Lojac.)Mattei.Two artifi cial ...As a dynamic ex situ conservation strategy,a clonal seed orchard was started in a nursery in Pomaio(POM)in central Italy in 1993 for an assisted migration experiment of Abies nebrodensis(Lojac.)Mattei.Two artifi cial ex situ populations were planted with this gene pool:a seedling arboretum in Pieve Santo Stefano(PSS)and a small dendrological collection in Papiano(PAP),both originating from the Sicilian relict population.Here,using AFLP markers,we estimated the relatedness among the relocated genotypes of the three collections to check whether the three collections had suffi cient genetic variability to be considered as additional sources of variability to the original gene pool for the assisted migration strategy.High individual genetic variability was found in the collections;each plant had a diff erent genotype and was confi rmed to belong to its population of origin.PAP and PSS trees were shown to be only from the original population of A.nebrodensis species and were derived from a limited set of maternal fertile genotypes.Based on the Sicilian fi r population inventory,nursery production in Sicily,and structure clustering analysis,close genetic relationships among POM,PAP and several PSS trees(1–35)were evident.Similarly,the PSS group(36–78)was genetically close to tree 1 of POM and in a lesser proportion to plants 7 and 9 of POM.The sampling of seedlings used to form batches in the nursery might have infl uenced the structure of the resultant plantations.All genotypes will be useful for enriching the original gene pool.展开更多
Various enhanced surfaces have been proposed over the years to improve boiling heat transfer. This paper introduces an experimental setup designed for boiling demonstration in the graduate-level Heat Transfer course. ...Various enhanced surfaces have been proposed over the years to improve boiling heat transfer. This paper introduces an experimental setup designed for boiling demonstration in the graduate-level Heat Transfer course. The pool boiling performance of water under atmospheric pressure of 1.025 bar is investigated by using several structured surfaces at heat fluxes of 28 and 35 kW/m<sup>2</sup>. Surfaces with holes, rectangular grooves, and mushroom fins are manufactured by an NC-controlled vertical milling machine. The heat flux versus excess temperature graph is plotted by using thermocouple measurements of water and base temperatures of the boiling vessel. The separation, rise, and growth of individual vapor bubbles from the surface during boiling were recorded with a digital camera. The results for the plain surface are compared to the Rohsenow correlation. The enhancement of heat transfer coefficient (h) ranged between 15% - 44.5% for all structured surfaces. The highest heat transfer coefficient enhancement is observed between 41% - 56.5% for holed surface-3 (405 holes) compared to the plain surface. The excess temperature dropped around 29% - 34% for holed surface-3 (405 holes) compared to the plain surface. The heat transfer coefficient increases as the spacing between channels or holes decreases. While the bubbles on holed and mushroomed surfaces were spherical, the bubbles on the flat and grooved surfaces were observed as formless. The suggested economical test design could be appropriate to keep students focused and participating in the classroom.展开更多
Background: Tuberculosis (TB) diagnostics, such as Xpert MTB/RIF, is still limited by cost. Testing of pooled samples from presumptive TB patients has been thought as a cost-saving strategy to diagnose TB. We assessed...Background: Tuberculosis (TB) diagnostics, such as Xpert MTB/RIF, is still limited by cost. Testing of pooled samples from presumptive TB patients has been thought as a cost-saving strategy to diagnose TB. We assessed the utility and cost-saving of pooled Xpert MTB/RIF testing strategy for the diagnosis of TB in Mwanza, Tanzania. Methods: Sputum samples from Presumptive TB patients were submitted to TB laboratory for routine diagnosis of TB using Xpert MTB/RIF. The TB results from the individual sputum samples were used as the reference standard and were concealed to the investigating laboratory technicians. The remainder of samples were collected serially and were pooled (5 samples per pool) for testing. The agreement of the results between individual sample testing against pooled sample testing and cost-savings was assessed. Results: A total of 250 sputum samples from presumptive TB patients were analyzed and 50 pools were made with each pool containing 5 samples. Of the 50 sputum pools made, Mycobacterium tuberculosis (MTB) was detected in 17 (34.0%) pools. Results from the individual sputum samples MTB/RIF testing were retrieved for all 250 samples and there were 28 (11.2%) samples in which MTB was detected whereas 222 (88.8%) samples had no MTB detected. Following re-analysis of positive pools, all 28 (100%) individual positive MTB samples were detected within the 17 positive pools, with 1 to 3 individual MTB positive samples per pool. The individual sputum samples were correctly identified by pooled sputum on Xpert MTB/RIF testing, with the sensitivity of 100% and specificity of 100%. Using pooling of sputum samples strategy, we saved 46.0% (115/250) of the cartridges. Conclusion: The pooled sputum testing strategy reduced cartridge costs by 46.0% and has the potential to increase the affordability of Xpert MTB/RIF testing in countries with limited resources, such as Tanzania.展开更多
基金The authors gratefully acknowledge the support of the Enhancement Strategy of Multi-Type Energy Integration of Active Distribution Network(YNKJXM20220113).
文摘In the framework of vigorous promotion of low-carbon power system growth as well as economic globalization,multi-resource penetration in active distribution networks has been advancing fiercely.In particular,distributed generation(DG)based on renewable energy is critical for active distribution network operation enhancement.To comprehensively analyze the accessing impact of DG in distribution networks from various parts,this paper establishes an optimal DG location and sizing planning model based on active power losses,voltage profile,pollution emissions,and the economics of DG costs as well as meteorological conditions.Subsequently,multiobjective particle swarm optimization(MOPSO)is applied to obtain the optimal Pareto front.Besides,for the sake of avoiding the influence of the subjective setting of the weight coefficient,the decisionmethod based on amodified ideal point is applied to execute a Pareto front decision.Finally,simulation tests based on IEEE33 and IEEE69 nodes are designed.The experimental results show thatMOPSO can achieve wider and more uniformPareto front distribution.In the IEEE33 node test system,power loss,and voltage deviation decreased by 52.23%,and 38.89%,respectively,while taking the economy into account.In the IEEE69 test system,the three indexes decreased by 19.67%,and 58.96%,respectively.
文摘In convolutional neural networks,pooling methods are used to reduce both the size of the data and the number of parameters after the convolution of the models.These methods reduce the computational amount of convolutional neural networks,making the neural network more efficient.Maximum pooling,average pooling,and minimum pooling methods are generally used in convolutional neural networks.However,these pooling methods are not suitable for all datasets used in neural network applications.In this study,a new pooling approach to the literature is proposed to increase the efficiency and success rates of convolutional neural networks.This method,which we call MAM(Maximum Average Minimum)pooling,is more interactive than other traditional maximum pooling,average pooling,and minimum pooling methods and reduces data loss by calculating the more appropriate pixel value.The proposed MAM pooling method increases the performance of the neural network by calculating the optimal value during the training of convolutional neural networks.To determine the success accuracy of the proposed MAM pooling method and compare it with other traditional pooling methods,training was carried out on the LeNet-5 model using CIFAR-10,CIFAR-100,and MNIST datasets.According to the results obtained,the proposed MAM pooling method performed better than the maximum pooling,average pooling,and minimum pooling methods in all pool sizes on three different datasets.
文摘Pooling,unpooling/specialization,and discretionary task completion are typical operational strategies in queueing systems that arise in healthcare,call centers,and online sales.These strategies may have advantages and disadvantages in different operational environments.This paper uses the M/M/1 and M/M/2 queues to study the impact of pooling,specialization,and discretionary task completion on the average queue length.Closed-form solutions for the average M/M/2 queue length are derived.Computational examples illustrate how the average queue length changes with the strength of pooling,specialization,and discretionary task completion.Finally,several conjectures are made in the paper.
基金supported by the Guangdong Basic and Applied Basic Research Foundation(2023A1515011244).
文摘The state of in situ stress is a crucial parameter in subsurface engineering,especially for critical projects like nuclear waste repository.As one of the two ISRM suggested methods,the overcoring(OC)method is widely used to estimate the full stress tensors in rocks by independent regression analysis of the data from each OC test.However,such customary independent analysis of individual OC tests,known as no pooling,is liable to yield unreliable test-specific stress estimates due to various uncertainty sources involved in the OC method.To address this problem,a practical and no-cost solution is considered by incorporating into OC data analysis additional information implied within adjacent OC tests,which are usually available in OC measurement campaigns.Hence,this paper presents a Bayesian partial pooling(hierarchical)model for combined analysis of adjacent OC tests.We performed five case studies using OC test data made at a nuclear waste repository research site of Sweden.The results demonstrate that partial pooling of adjacent OC tests indeed allows borrowing of information across adjacent tests,and yields improved stress tensor estimates with reduced uncertainties simultaneously for all individual tests than they are independently analysed as no pooling,particularly for those unreliable no pooling stress estimates.A further model comparison shows that the partial pooling model also gives better predictive performance,and thus confirms that the information borrowed across adjacent OC tests is relevant and effective.
文摘In order to enhance the performance of the CNN-based segmentation models for bone metastases, this study proposes a segmentation method that integrates dual-pooling, DAC, and RMP modules. The network consists of distinct feature encoding and decoding stages, with dual-pooling modules employed in encoding stages to maintain the background information needed for bone scintigrams diagnosis. Both the DAC and RMP modules are utilized in the bottleneck layer to address the multi-scale problem of metastatic lesions. Experimental evaluations on 306 clinical SPECT data have demonstrated that the proposed method showcases a substantial improvement in both DSC and Recall scores by 3.28% and 6.55% compared the baseline. Exhaustive case studies illustrate the superiority of the methodology.
文摘Liver transplantation(LT)provides a life-saving option for cirrhotic patients with complications and hepatocellular carcinoma.Despite the increasing number of liver transplants performed each year,the number of LT candidates on the waitlist remains unchanged due to an imbalance between donor organ supply and the demand which increases the waitlist time and mortality.Living donor liver transplant had a great role in increasing the donor pool and shortened waitlist time for LT candidates.Nevertheless,further strategies can be implemented to increase the pool of potential donors in deceased donor LT,such as reducing the rate of organ discards.Utilizing hepatitis C virus(HCV)seropositive liver grafts is one of the expanded donor organ criteria.A yearly increase of hundreds of transplants is anticipated as a result of maximizing the utilization of HCV-positive organs for HCV-negative recipients.Direct-acting antiviral therapy's efficacy has revolutionized the treatment of HCV infection and the use of HCV-seropositive donors in transplantation.The American Society of Transplantation advises against performing transplants from HCV-infected liver donors(D+)into HCV-negative recipient(R-)unless under Institutional Review Board-approved study rules and with full informed consent of the knowledge gaps associated with such transplants.Proper selection of patients to be transplanted with HCV-infected grafts and confirming their access to direct-acting antivirals if needed is im-portant.National and international consensuses are needed to regulate this process to ensure the maximum benefit and the least adverse events.
基金supported by the National Science and Technology Plan (Major Project of the Eleventh Five-Year Plan,Grant No. 2006BAB04A13)the Philosophy and Social Science Fund of the Education Department of Jiangsu Province (Grant No.07SJD630006)+2 种基金the Third Key Discipline (Techno-Economics and Management) of the 211 Projectthe Key Discipline of Jiangsu Province (Engineering and Project Management)the Office of the South-to-North Water Diversion Project Construction Committee under the State Council
文摘Recently, the critical chain study has become a hot issue in the project management research field. The construction of the critical chain with multi-resource constraints is a new research subject. According to the system analysis theory and project portfolio theory, this paper discusses the creation of project portfolios based on the similarity principle and gives the definition of priority in multi-resource allocation based on quantitative analysis. A model with multi-resource constraints, which can be applied to the critical chain construction of the A-bid section in the South-to-North Water Diversion Project, was proposed. Contrast analysis with the comprehensive treatment construction method and aggressive treatment construction method was carried out. This paper also makes suggestions for further research directions and subjects, which will be useful in improving the theories in relevant research fields.
基金financial support of the Oversea Study Program of the Guangzhou Elite Project(GEP)supported by the National Natural Science Foundation of China under Grant 61471173Guangdong Science Technology Project(no:2017A010101027)
文摘This paper addresses multi-resource fair allocation: a fundamental research topic in cloud computing. To improve resource utilization under well-studied fairness constraints, we propose a new allocation mechanism called Dominant Resource with Bottlenecked Fairness(DRBF), which generalizes Bottleneck-aware Allocation(BAA) to the settings of Dominant Resource Fairness(DRF). We classify users into different queues by their dominant resources. The goals are to ensure that users in the same queue receive allocations in proportion to their fair shares while users in different queues receive allocations that maximize resource utilization subject to well-studied fairness properties such as those in DRF. Under DRBF, no user 1) is worse off sharing resources than dividing resources equally among all users; 2) prefers the allocation of another user; 3) can improve their own allocation without reducing other users' allocations; and(4) can benefit by misreporting their resource demands. Experiments demonstrate that the proposed allocation policy performs better in terms of high resource utilization than does DRF.
基金the National Natural Science Foundation of China under Grant 61701054the Fundamental Research Funds for the Central University under Grants 2020CDJQY-A001 and 2021CDJQY-013。
文摘The six-generation(6G)wireless network is expected to satisfy the requirements of ubiquitous connectivity and intelligent endogenous.Terrestrialsatellite networks(TSN)enable seamless coverage for terrestrial users in a wide area,making it very promising in 6G.As data traffic in TSNs surges,the integrated management for caching,computing,and communication(3C)has attracted much research attention.In this paper,we investigate the multi-resource management in the uplink and downlink transmission of TSN,respectively.In particularly,we aim to guarantee both throughput fairness and data security in the uplink transmission of TSN.Considering the intermittent communication of the satellite,we introduce two kinds of relays,i.e.,terrestrial relays(TRs)and aerial relays(ARs)to improve the system throughput performance in the downlink transmission of TSN.Finally,we study a specific case of TSN with the uplink and downlink transmission,and the corresponding simulation results validate the effectiveness of our proposed schemes.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.52161002,51661020,and11364024)the Postdoctoral Science Foundation of China(Grant No.2014M560371)the Funds for Distinguished Young Scientists of Lanzhou University of Technology of China(Grant No.J201304)。
文摘We use the phase field method to track the gas-liquid interface based on the gas-liquid two-phase flow in the pool boiling process,and study the bubble nucleation,growth,deformation,departure and other dynamic behaviors on the heating surface under microgravity.By simulating the correlation between liquid undercooling and bubble dynamics,we find that the bubble growth time increases with the increase of liquid undercooling,but the effect of liquid undercooling on bubble height is not significant.Meanwhile,the gas-liquid-solid three-phase contact angle and the gravity level will also have an effect on the bubble growth time and bubble height.With the increase of the contact angle,the bubble growth time and bubble height when the bubble departs also increase.While the effect of gravity level is on the contrary,the smaller the gravity level is,the larger the bubble height and bubble growth time when the bubble separates.
基金funded by the Italian Ministry for Agriculture,Food and Forestry Policies in the framework of the“FAO-RGV(FAO-Vegetal Genetic Resources)Project”.
文摘As a dynamic ex situ conservation strategy,a clonal seed orchard was started in a nursery in Pomaio(POM)in central Italy in 1993 for an assisted migration experiment of Abies nebrodensis(Lojac.)Mattei.Two artifi cial ex situ populations were planted with this gene pool:a seedling arboretum in Pieve Santo Stefano(PSS)and a small dendrological collection in Papiano(PAP),both originating from the Sicilian relict population.Here,using AFLP markers,we estimated the relatedness among the relocated genotypes of the three collections to check whether the three collections had suffi cient genetic variability to be considered as additional sources of variability to the original gene pool for the assisted migration strategy.High individual genetic variability was found in the collections;each plant had a diff erent genotype and was confi rmed to belong to its population of origin.PAP and PSS trees were shown to be only from the original population of A.nebrodensis species and were derived from a limited set of maternal fertile genotypes.Based on the Sicilian fi r population inventory,nursery production in Sicily,and structure clustering analysis,close genetic relationships among POM,PAP and several PSS trees(1–35)were evident.Similarly,the PSS group(36–78)was genetically close to tree 1 of POM and in a lesser proportion to plants 7 and 9 of POM.The sampling of seedlings used to form batches in the nursery might have infl uenced the structure of the resultant plantations.All genotypes will be useful for enriching the original gene pool.
文摘Various enhanced surfaces have been proposed over the years to improve boiling heat transfer. This paper introduces an experimental setup designed for boiling demonstration in the graduate-level Heat Transfer course. The pool boiling performance of water under atmospheric pressure of 1.025 bar is investigated by using several structured surfaces at heat fluxes of 28 and 35 kW/m<sup>2</sup>. Surfaces with holes, rectangular grooves, and mushroom fins are manufactured by an NC-controlled vertical milling machine. The heat flux versus excess temperature graph is plotted by using thermocouple measurements of water and base temperatures of the boiling vessel. The separation, rise, and growth of individual vapor bubbles from the surface during boiling were recorded with a digital camera. The results for the plain surface are compared to the Rohsenow correlation. The enhancement of heat transfer coefficient (h) ranged between 15% - 44.5% for all structured surfaces. The highest heat transfer coefficient enhancement is observed between 41% - 56.5% for holed surface-3 (405 holes) compared to the plain surface. The excess temperature dropped around 29% - 34% for holed surface-3 (405 holes) compared to the plain surface. The heat transfer coefficient increases as the spacing between channels or holes decreases. While the bubbles on holed and mushroomed surfaces were spherical, the bubbles on the flat and grooved surfaces were observed as formless. The suggested economical test design could be appropriate to keep students focused and participating in the classroom.
文摘Background: Tuberculosis (TB) diagnostics, such as Xpert MTB/RIF, is still limited by cost. Testing of pooled samples from presumptive TB patients has been thought as a cost-saving strategy to diagnose TB. We assessed the utility and cost-saving of pooled Xpert MTB/RIF testing strategy for the diagnosis of TB in Mwanza, Tanzania. Methods: Sputum samples from Presumptive TB patients were submitted to TB laboratory for routine diagnosis of TB using Xpert MTB/RIF. The TB results from the individual sputum samples were used as the reference standard and were concealed to the investigating laboratory technicians. The remainder of samples were collected serially and were pooled (5 samples per pool) for testing. The agreement of the results between individual sample testing against pooled sample testing and cost-savings was assessed. Results: A total of 250 sputum samples from presumptive TB patients were analyzed and 50 pools were made with each pool containing 5 samples. Of the 50 sputum pools made, Mycobacterium tuberculosis (MTB) was detected in 17 (34.0%) pools. Results from the individual sputum samples MTB/RIF testing were retrieved for all 250 samples and there were 28 (11.2%) samples in which MTB was detected whereas 222 (88.8%) samples had no MTB detected. Following re-analysis of positive pools, all 28 (100%) individual positive MTB samples were detected within the 17 positive pools, with 1 to 3 individual MTB positive samples per pool. The individual sputum samples were correctly identified by pooled sputum on Xpert MTB/RIF testing, with the sensitivity of 100% and specificity of 100%. Using pooling of sputum samples strategy, we saved 46.0% (115/250) of the cartridges. Conclusion: The pooled sputum testing strategy reduced cartridge costs by 46.0% and has the potential to increase the affordability of Xpert MTB/RIF testing in countries with limited resources, such as Tanzania.
文摘热轧带钢是钢铁行业的重要产品,其表面缺陷是影响产品质量的重要因素。针对传统缺陷检测算法存在的过程繁琐、精度不足和效率低下等问题,提出一种基于改进更快速区域卷积神经网络(faster region-based convolutional neural network,Faster R-CNN)的检测算法,实现对热轧带钢表面缺陷的高效、高精度检测。首先,采用特征相加的方法对底层细节特征和高层语义特征进行融合;然后,采用精准的感兴趣区域池化(precise region of interest pooling,Precise ROI Pooling)获取固定大小的特征向量,避免特征出现位置偏差;最后,利用均值偏移聚类算法对带钢数据集进行聚类,获得适用于热轧带钢表面缺陷检测的先验框尺寸。实验结果表明,所提算法在热轧带钢表面缺陷检测数据集上的平均精度均值达到了85.34%,检测速度为23.5帧/s,且鲁棒性良好,满足实际的工业检测需求。