Chronic active hepatitis(CAH) is acknowledged as an imperative risk factor for the development of liver injury and hepatocellular carcinoma.The histological end points of CAH are chronic inflammation,fibrosis and cirr...Chronic active hepatitis(CAH) is acknowledged as an imperative risk factor for the development of liver injury and hepatocellular carcinoma.The histological end points of CAH are chronic inflammation,fibrosis and cirrhosis which are coupled with increased DNA synthesis in cirrhotic vs healthy normal livers.The potential mechanism involved in CAH includes a combination of processes leading to liver cell necrosis,inflammation and cytokine production and liver scaring(fibrosis).The severity of liver damage is regulated by Hepatitis B virus genotypes and viral components.The viral and cellular factors that contribute to liver injury are discussed in this article.Liver injury caused by the viral infection affects many cellular processes such as cell signaling,apoptosis,transcription,DNA repair which in turn induce radical effects on cell survival,growth,transformation and maintenance.The consequence of such perturbations is resulted in the alteration of bile secretion,gluconeogenesis,glycolysis,detoxification and metabolism of carbohydrates,proteins,fat and balance of nutrients.The identification and elucidation of the molecular pathways perturbed by the viral proteins are important in order to design effective strategy to minimize and/or restore the hepatocytes injury.展开更多
The support structure of a rotor system is subject to vibration excitation,which results in the stiffness of the support structure varying with the excitation frequency(i.e.,the dynamic stiffness).However,the dynamic ...The support structure of a rotor system is subject to vibration excitation,which results in the stiffness of the support structure varying with the excitation frequency(i.e.,the dynamic stiffness).However,the dynamic stiffness and its effect mechanism have been rarely incorporated in open studies of the rotor system.Therefore,this study theoretically reveals the effect mechanism of dynamic stiffness on the rotor system.Then,the numerical study and experimental verification are conducted on the dynamic stiffness characteristics of a squirrel cage,which is a common support structure for aero-engine.Moreover,the static stiffness experiment is also performed for comparison.Finally,a rotor system model considering the dynamic stiffness of the support structure is presented.The presented rotor model is used to validate the results of the theoretical analysis.The results illustrate that the dynamic stiffness reduces the critical speed of the rotor system and may lead to a new resonance.展开更多
The harmonics that appear in the squirrel cage asynchronous machine have been discussed in great detail in the literature for a long time. However, the systematization of the phenomenon is still pending, so we made an...The harmonics that appear in the squirrel cage asynchronous machine have been discussed in great detail in the literature for a long time. However, the systematization of the phenomenon is still pending, so we made an attempt to fill this gap in the previous parts of our study by elaborating formulas for calculation of parasitic torques. It was a general demand among those who work in this field towards the author to verify his formulas with measurements. In the literature, it seems,only one detailed, purposeful series of measurements has been published so far, the purpose of which was to investigate the effect of the number of rotor slots on the torque-speed characteristic curve of the machine. The main goal of this study is to verify the correctness of the formulas by comparing them with the referred series of measurements. Relying on this, the expected synchronous parasitic torques were developed for the frequently used rotor slot numbers-as a design guide for the engineer.Thus, together with our complete table for radial magnetic pull published in our previous work, the designer has all the principles, data and formulas available for the right number of rotor slots for his given machine and for the drive system. This brings this series of papers to an end.展开更多
Micro RNAs（mi RNAs） are small non-coding RNAs that are important in regulating metabolic stress. In this study, we determined the expression and structural characteristics of 20 mi RNAs in brown（BAT） and white adi...Micro RNAs（mi RNAs） are small non-coding RNAs that are important in regulating metabolic stress. In this study, we determined the expression and structural characteristics of 20 mi RNAs in brown（BAT） and white adipose tissue（WAT） during torpor in thirteen-lined ground squirrels. Using a modified stem-loop technique, we found that during torpor, expression of six mi RNAs including let-7a, let-7b, mi R-107, mi R-150, mi R-222 and mi R-31 was significantly downregulated in WAT（P 〈 0.05）, which was 16%–54% of euthermic non-torpid control squirrels,whereas expression of three mi RNAs including mi R-143, mi R-200 a and mi R-519 d was found to be upregulated by 1.32–2.34-fold. Similarly, expression of more mi RNAs was downregulated in BAT during torpor. We detected reduced expression of 6 mi RNAs including mi R-103 a, mi R-107, mi R-125 b, mi R-21, mi R-221 and mi R-31（48%–70% of control）, while only expression of mi R-138 was significantly upregulated（2.91 ± 0.8-fold of the control, P 〈 0.05）. Interestingly,mi RNAs found to be downregulated in WAT during torpor were similar to those dysregulated in obese humans for increased adipogenesis, whereas mi RNAs with altered expression in BAT during torpor were linked to mitochondrial b-oxidation. mi RPath target prediction analysis showed that mi RNAs downregulated in both WAT and BAT were associated with the regulation of mitogen-activated protein kinase（MAPK） signaling, while the mi RNAs upregulated in WAT were linked to transforming growth factor b（TGFb） signaling. Compared to mouse sequences, no unique nucleotide substitutions within the stem-loop region were discovered for the associated pre-mi RNAs for the mi RNAs used in this study, suggesting no structure-influenced changes in pre-mi RNA processing efficiency in the squirrel. As well, the expression of mi RNA processingenzyme Dicer remained unchanged in both tissues during torpor. Overall, our findings suggest that changes of mi RNA expression in adipose tissues may be linked展开更多
Concrete is the most commonly used construction material.However,its production leads to high carbon dioxide(CO_(2))emissions and energy consumption.Therefore,developing waste-substitutable concrete components is nece...Concrete is the most commonly used construction material.However,its production leads to high carbon dioxide(CO_(2))emissions and energy consumption.Therefore,developing waste-substitutable concrete components is necessary.Improving the sustainability and greenness of concrete is the focus of this research.In this regard,899 data points were collected from existing studies where cement,slag,fly ash,superplasticizer,coarse aggregate,and fine aggregate were considered potential influential factors.The complex relationship between influential factors and concrete compressive strength makes the prediction and estimation of compressive strength difficult.Instead of the traditional compressive strength test,this study combines five novel metaheuristic algorithms with extreme gradient boosting(XGB)to predict the compressive strength of green concrete based on fly ash and blast furnace slag.The intelligent prediction models were assessed using the root mean square error(RMSE),coefficient of determination(R^(2)),mean absolute error(MAE),and variance accounted for(VAF).The results indicated that the squirrel search algorithm-extreme gradient boosting(SSA-XGB)yielded the best overall prediction performance with R^(2) values of 0.9930 and 0.9576,VAF values of 99.30 and 95.79,MAE values of 0.52 and 2.50,RMSE of 1.34 and 3.31 for the training and testing sets,respectively.The remaining five prediction methods yield promising results.Therefore,the developed hybrid XGB model can be introduced as an accurate and fast technique for the performance prediction of green concrete.Finally,the developed SSA-XGB considered the effects of all the input factors on the compressive strength.The ability of the model to predict the performance of concrete with unknown proportions can play a significant role in accelerating the development and application of sustainable concrete and furthering a sustainable economy.展开更多
The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field, as well as the related differential leakage, attenuation, asynch...The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field, as well as the related differential leakage, attenuation, asynchronous parasitic torques have been discussed in great detail in the literature, but always separately, for a long time. However, systematization of the phenomenon still awaits. Therefore, it is worth summarizing the completeness of the phenomena in a single study – with a new approach at the same time-in order to reveal the relationships between them. The role of rotor slot number is emphasized much more than before. An existing, commonly used, but still impractical basic figure has been modified to more clearly demonstrate the response of the rotor for the harmonics of the stator. The need to treat differential leakage, asynchronous parasitic torques and attenuation together will be demonstrated: new formula for asynchronous parasitic torque is derived;the long-used characteristic curves for differential leakage and attenuation used separately so far was merged into one, correct curve in order to provide a correct design guide for the engineers.展开更多
Human pose estimation(HPE)is a procedure for determining the structure of the body pose and it is considered a challenging issue in the computer vision(CV)communities.HPE finds its applications in several fields namel...Human pose estimation(HPE)is a procedure for determining the structure of the body pose and it is considered a challenging issue in the computer vision(CV)communities.HPE finds its applications in several fields namely activity recognition and human-computer interface.Despite the benefits of HPE,it is still a challenging process due to the variations in visual appearances,lighting,occlusions,dimensionality,etc.To resolve these issues,this paper presents a squirrel search optimization with a deep convolutional neural network for HPE(SSDCNN-HPE)technique.The major intention of the SSDCNN-HPE technique is to identify the human pose accurately and efficiently.Primarily,the video frame conversion process is performed and pre-processing takes place via bilateral filtering-based noise removal process.Then,the EfficientNet model is applied to identify the body points of a person with no problem constraints.Besides,the hyperparameter tuning of the EfficientNet model takes place by the use of the squirrel search algorithm(SSA).In the final stage,the multiclass support vector machine(M-SVM)technique was utilized for the identification and classification of human poses.The design of bilateral filtering followed by SSA based EfficientNetmodel for HPE depicts the novelty of the work.To demonstrate the enhanced outcomes of the SSDCNN-HPE approach,a series of simulations are executed.The experimental results reported the betterment of the SSDCNN-HPE system over the recent existing techniques in terms of different measures.展开更多
In data mining and machine learning,feature selection is a critical part of the process of selecting the optimal subset of features based on the target data.There are 2n potential feature subsets for every n features ...In data mining and machine learning,feature selection is a critical part of the process of selecting the optimal subset of features based on the target data.There are 2n potential feature subsets for every n features in a dataset,making it difficult to pick the best set of features using standard approaches.Consequently,in this research,a new metaheuristics-based feature selection technique based on an adaptive squirrel search optimization algorithm(ASSOA)has been proposed.When using metaheuristics to pick features,it is common for the selection of features to vary across runs,which can lead to instability.Because of this,we used the adaptive squirrel search to balance exploration and exploitation duties more evenly in the optimization process.For the selection of the best subset of features,we recommend using the binary ASSOA search strategy we developed before.According to the suggested approach,the number of features picked is reduced while maximizing classification accuracy.A ten-feature dataset from the University of California,Irvine(UCI)repository was used to test the proposed method’s performance vs.eleven other state-of-the-art approaches,including binary grey wolf optimization(bGWO),binary hybrid grey wolf and particle swarm optimization(bGWO-PSO),bPSO,binary stochastic fractal search(bSFS),binary whale optimization algorithm(bWOA),binary modified grey wolf optimization(bMGWO),binary multiverse optimization(bMVO),binary bowerbird optimization(bSBO),binary hybrid GWO and genetic algorithm 4028 CMC,2023,vol.74,no.2(bGWO-GA),binary firefly algorithm(bFA),and bGAmethods.Experimental results confirm the superiority and effectiveness of the proposed algorithm for solving the problem of feature selection.展开更多
The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field,as well as the synchronous parasitic torques,radial magnetic forc...The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field,as well as the synchronous parasitic torques,radial magnetic forces have been discussed in great detail in the literature,but always separately,for a long time.However,systematization of the phenomenon still awaits.Therefore,it is worth summarizing the completeness of the phenomena in a single study–with a new approach at the same time-in order to reveal the relationships between them.The role of rotor slot number is emphasized much more than before.New formulas derived for both synchronous torques and radial magnetic forces are used for further investigation.It will be shown that both phenomena in subject must be treated together.Formulas will be provided to take into account attenuation.Design guide will be provided to avoid dangerous rotor slot numbers.It will be shown that the generation of synchronous torques and radial magnetic forces do not depend–in this new approach-on the slot combination,but on the rotor slot number itself.展开更多
The flying squirrels(Pteromyini,Rodentia)are the most diverse and widely distributed group of gliding mammals.Taxonomic boundaries and relationships within flying squirrels remain an area of active research in mammalo...The flying squirrels(Pteromyini,Rodentia)are the most diverse and widely distributed group of gliding mammals.Taxonomic boundaries and relationships within flying squirrels remain an area of active research in mammalogy.The discovery of new specimens of Pteromys(Hylopetes)leonardi Thomas,1921,previously considered a synonym of Hylopetes alboniger,in Yunnan Province,China allowed a morphological and genetic reassessment of the status of this taxon.Phylogenetic reconstruction was implemented using sequences of two mitochondrial(12S ribosomal RNA and 16S ribosomal RNA)and one nuclear(interphotoreceptor retinoid-binding protein)gene fragments.Morphological assessments involved examinations of features preserved on skins,skulls,and penises of museum specimens,supplemented with principal component analysis of craniometric data.Together these assessments revealed that this taxon should be recognized not only as a distinct species,but should also be placed within a new genus,described here as Priapomys gen.nov.展开更多
Urbanization of animal habitats has the potential to affect the natural communication systems of any species able to survive in the changed environment. Urban animals such as squirrels use multiple signal channels to ...Urbanization of animal habitats has the potential to affect the natural communication systems of any species able to survive in the changed environment. Urban animals such as squirrels use multiple signal channels to communicate, but it is un- known how ttrbanization has affected these behaviors. Multimodal commtmication, involving more than one sensory modality, can be studied by use of biomimetic mechanical animal models that are designed to simulate the multimodal signals and be pre- sented to animal subjects in the field. In this way the responses to the various signal components can be compared and contrasted to determine whether the multimodal signal is made up of redundant or nonredundant components. In this study, we presented wild gray squirrels in relatively urban and relatively rural habitats in Western Massachusetts with a biomimetic squirrel model that produced tail flags and alarm barks in a variety of combinations. We found that the squirrels responded to each unimodal component on its own, the bark and tail flag, but they responded most to the complete multimodal signal, containing both the acoustic and the moving visual components, providing evidence that in this context the signal components are redundant and that their combination elicits multimodal enhancement. We expanded on the results of Partan et al. （2009） by providing data on sig- naling behavior in the presence and absence of conspecifics, suggesting that alarm signaling is more likely if conspecifics are present. We found that the squirrels were more active in the urban habitats and that they responded more to tail flagging in the urban habitats as compared to the rural ones, suggesting the interesting possibility of a multimodal shift from reliance on audio to visual signals in noisier more crowded urban habitats [Current Zoology 56 （3）： 313-326, 2010].展开更多
To study the influence of skewed rotors and different skew angles on the losses of squirrel cage asynchronous motors,a 5.5-kW motor was taken as an example and the multi-sliced field-circuit coupled time stepping fini...To study the influence of skewed rotors and different skew angles on the losses of squirrel cage asynchronous motors,a 5.5-kW motor was taken as an example and the multi-sliced field-circuit coupled time stepping finite element method(T-S FEM)was used to analyze the axially non-uniform fundamental and harmonic field distribution characteristics at typical locations in the stator and rotor cores.The major conclusions are:firstly the skewed rotor exhibits a decrease in the harmonic copper losses caused by slot harmonic currents in the stator winding and rotor bars.Secondly,the skewed rotor shifts the non-uniform distribution of field in the axial direction,which leads to more severe saturation and an increase in iron losses.The heavier the load,the more pronounced the increase in iron losses.Furthermore,the influences of different skew angles on motor losses are studied systematically,with skew angles from 0.5 to 1.5 stator tooth pitch.It is found that the lowest total loss occurs at 0.8 stator tooth pitch,and the slot harmonics can be decreased effectively.展开更多
The purpose of this study was to explore the variations in the circulating leptin concentrations of the wild ground squirrels in relation to seasonal changes in testicular activities.Hematoxylin-eosin staining showed ...The purpose of this study was to explore the variations in the circulating leptin concentrations of the wild ground squirrels in relation to seasonal changes in testicular activities.Hematoxylin-eosin staining showed all types of elongated spermatids and spermatogenic cells existed in the testis in April,while the primary spermatocytes and spermatogonia were most advanced stages of germ cells in June.In addition,the primary spermatocytes,secondary spermatocytes,and spermatogonia were most advanced stages of germ cells in September.The highest circulating leptin concentration was consistent with the maximum body weight results from accumulation of adipose tissue in September.The mRNA expression level of leptin receptor(Ob-R)and STAT3 was lowest in June,raised in September,and remained increased in April.Ob-R and STAT3 were stronger staining in the Leydig cells in July.Moreover,the concentrations of testosterone(T)showed the maximum values in April,the minimum values in June,and significant increases in September.Furthermore,it is worth noting that the levels of T increased with the mRNA levels of Ob-R,STAT3,StAR,and testicular steroidogenic enzymes(3β-HSD,P450c17,and P450scc).Moreover,RNA-seq analyses of testis during the different periods showed that a total of 4209 genes were differ-entially expressed genes(DEGs);further analysis revealed that DEGs related with the Jak/STAT pathways and reproduction were altered.Taken together,the results suggested that the leptin regulated testicular function through the Jak/STAT pathways and testicular steroidogenic factor expressions.展开更多
To figure out the load distribution of thin-section rolling bearing supported by flexible structure with squirrel cage and the distribution's influence on bearing life,an iterative FEA method is proposed to use th...To figure out the load distribution of thin-section rolling bearing supported by flexible structure with squirrel cage and the distribution's influence on bearing life,an iterative FEA method is proposed to use the result calculated from the Quasi-Dynamic model based on the rigid support hypothesis. The contact angle,contact position and stiffness of equivalent spring are modified during the iterative FEA to optimize the FEA model,and then the bearings' life can be predicted when the error is below 0.5%. It can be concluded that from the analysis results the load distribution under flexible support is more uniform than that of the rigid support,while the maximum load decreases by 11.2% and bearing life increases by 14.7%. The analysis result of different values of thickness of bearing house,rings and hollow shaft demonstrates the thicknesses of bearing house and hollow shaft have a greater influence on the load's uniformity and bearing's life than those of the rings.展开更多
Inspired by creatures with membrane to obtain ultra-high gliding ability, this paper presents a robotic flying squirrel （a novel gliding robot） characterized as membrane wing and active membrane deformation. For dee...Inspired by creatures with membrane to obtain ultra-high gliding ability, this paper presents a robotic flying squirrel （a novel gliding robot） characterized as membrane wing and active membrane deformation. For deep understanding of membrane wing and gliding mechanism from a robotic system perspective, a simplified blocking aerodynamic model of the deformable membrane wing and CFD simulation are finished. In addition, a physical prototype is developed and wind tunnel experiments are carried out. The results show that the proposed membrane wing is able to support the gliding action of the robot. Meanwhile, factors including geometry characteristics, material property and wind speed are considered in the experiments to investigate the aerodynamic effects of the deformable membrane wing deeply. As a typical characteristic of robotic flying squirrel, deformation modes of the membrane wing not only affect the gliding ability, but also directly determine the effects of the posture adjustment. Moreover, different deformation modes of membrane wing are illustrated to explore the possible effects of active membrane deformation on the gliding performance. The results indicate that the deformation modes have a significant impact on posture adjustment, which reinforces the rationality of flying squirrel＇s gliding strategy and provides valuable information on prototype optimal design and control strategy in the actual gliding process.展开更多
文摘Chronic active hepatitis(CAH) is acknowledged as an imperative risk factor for the development of liver injury and hepatocellular carcinoma.The histological end points of CAH are chronic inflammation,fibrosis and cirrhosis which are coupled with increased DNA synthesis in cirrhotic vs healthy normal livers.The potential mechanism involved in CAH includes a combination of processes leading to liver cell necrosis,inflammation and cytokine production and liver scaring(fibrosis).The severity of liver damage is regulated by Hepatitis B virus genotypes and viral components.The viral and cellular factors that contribute to liver injury are discussed in this article.Liver injury caused by the viral infection affects many cellular processes such as cell signaling,apoptosis,transcription,DNA repair which in turn induce radical effects on cell survival,growth,transformation and maintenance.The consequence of such perturbations is resulted in the alteration of bile secretion,gluconeogenesis,glycolysis,detoxification and metabolism of carbohydrates,proteins,fat and balance of nutrients.The identification and elucidation of the molecular pathways perturbed by the viral proteins are important in order to design effective strategy to minimize and/or restore the hepatocytes injury.
基金the National Natural Science Foundation of China(Nos.11872148 and U1908217)the Fundamental Research Funds for the Central Universities of China(Nos.N2224001-4 and N2003013)the Basic and Applied Basic Research Foundation of Guangdong Province of China(No.2020B1515120015)。
文摘The support structure of a rotor system is subject to vibration excitation,which results in the stiffness of the support structure varying with the excitation frequency(i.e.,the dynamic stiffness).However,the dynamic stiffness and its effect mechanism have been rarely incorporated in open studies of the rotor system.Therefore,this study theoretically reveals the effect mechanism of dynamic stiffness on the rotor system.Then,the numerical study and experimental verification are conducted on the dynamic stiffness characteristics of a squirrel cage,which is a common support structure for aero-engine.Moreover,the static stiffness experiment is also performed for comparison.Finally,a rotor system model considering the dynamic stiffness of the support structure is presented.The presented rotor model is used to validate the results of the theoretical analysis.The results illustrate that the dynamic stiffness reduces the critical speed of the rotor system and may lead to a new resonance.
文摘The harmonics that appear in the squirrel cage asynchronous machine have been discussed in great detail in the literature for a long time. However, the systematization of the phenomenon is still pending, so we made an attempt to fill this gap in the previous parts of our study by elaborating formulas for calculation of parasitic torques. It was a general demand among those who work in this field towards the author to verify his formulas with measurements. In the literature, it seems,only one detailed, purposeful series of measurements has been published so far, the purpose of which was to investigate the effect of the number of rotor slots on the torque-speed characteristic curve of the machine. The main goal of this study is to verify the correctness of the formulas by comparing them with the referred series of measurements. Relying on this, the expected synchronous parasitic torques were developed for the frequently used rotor slot numbers-as a design guide for the engineer.Thus, together with our complete table for radial magnetic pull published in our previous work, the designer has all the principles, data and formulas available for the right number of rotor slots for his given machine and for the drive system. This brings this series of papers to an end.
基金supported by a Discovery grant from the Natural Sciences and Engineering Research Council (NSERC) of Canada (Grant No. 6793)supported by the NSERC postgraduate fellowships
文摘Micro RNAs（mi RNAs） are small non-coding RNAs that are important in regulating metabolic stress. In this study, we determined the expression and structural characteristics of 20 mi RNAs in brown（BAT） and white adipose tissue（WAT） during torpor in thirteen-lined ground squirrels. Using a modified stem-loop technique, we found that during torpor, expression of six mi RNAs including let-7a, let-7b, mi R-107, mi R-150, mi R-222 and mi R-31 was significantly downregulated in WAT（P 〈 0.05）, which was 16%–54% of euthermic non-torpid control squirrels,whereas expression of three mi RNAs including mi R-143, mi R-200 a and mi R-519 d was found to be upregulated by 1.32–2.34-fold. Similarly, expression of more mi RNAs was downregulated in BAT during torpor. We detected reduced expression of 6 mi RNAs including mi R-103 a, mi R-107, mi R-125 b, mi R-21, mi R-221 and mi R-31（48%–70% of control）, while only expression of mi R-138 was significantly upregulated（2.91 ± 0.8-fold of the control, P 〈 0.05）. Interestingly,mi RNAs found to be downregulated in WAT during torpor were similar to those dysregulated in obese humans for increased adipogenesis, whereas mi RNAs with altered expression in BAT during torpor were linked to mitochondrial b-oxidation. mi RPath target prediction analysis showed that mi RNAs downregulated in both WAT and BAT were associated with the regulation of mitogen-activated protein kinase（MAPK） signaling, while the mi RNAs upregulated in WAT were linked to transforming growth factor b（TGFb） signaling. Compared to mouse sequences, no unique nucleotide substitutions within the stem-loop region were discovered for the associated pre-mi RNAs for the mi RNAs used in this study, suggesting no structure-influenced changes in pre-mi RNA processing efficiency in the squirrel. As well, the expression of mi RNA processingenzyme Dicer remained unchanged in both tissues during torpor. Overall, our findings suggest that changes of mi RNA expression in adipose tissues may be linked
基金funding provided by the China Scholarship Council (Nos.202008440524 and 202006370006)supported by the Distinguished Youth Science Foundation of Hunan Province of China (No.2022JJ10073)+1 种基金Innovation Driven Project of Central South University (No.2020CX040)Shenzhen Sciencee and Technology Plan (No.JCYJ20190808123013260).
文摘Concrete is the most commonly used construction material.However,its production leads to high carbon dioxide(CO_(2))emissions and energy consumption.Therefore,developing waste-substitutable concrete components is necessary.Improving the sustainability and greenness of concrete is the focus of this research.In this regard,899 data points were collected from existing studies where cement,slag,fly ash,superplasticizer,coarse aggregate,and fine aggregate were considered potential influential factors.The complex relationship between influential factors and concrete compressive strength makes the prediction and estimation of compressive strength difficult.Instead of the traditional compressive strength test,this study combines five novel metaheuristic algorithms with extreme gradient boosting(XGB)to predict the compressive strength of green concrete based on fly ash and blast furnace slag.The intelligent prediction models were assessed using the root mean square error(RMSE),coefficient of determination(R^(2)),mean absolute error(MAE),and variance accounted for(VAF).The results indicated that the squirrel search algorithm-extreme gradient boosting(SSA-XGB)yielded the best overall prediction performance with R^(2) values of 0.9930 and 0.9576,VAF values of 99.30 and 95.79,MAE values of 0.52 and 2.50,RMSE of 1.34 and 3.31 for the training and testing sets,respectively.The remaining five prediction methods yield promising results.Therefore,the developed hybrid XGB model can be introduced as an accurate and fast technique for the performance prediction of green concrete.Finally,the developed SSA-XGB considered the effects of all the input factors on the compressive strength.The ability of the model to predict the performance of concrete with unknown proportions can play a significant role in accelerating the development and application of sustainable concrete and furthering a sustainable economy.
文摘The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field, as well as the related differential leakage, attenuation, asynchronous parasitic torques have been discussed in great detail in the literature, but always separately, for a long time. However, systematization of the phenomenon still awaits. Therefore, it is worth summarizing the completeness of the phenomena in a single study – with a new approach at the same time-in order to reveal the relationships between them. The role of rotor slot number is emphasized much more than before. An existing, commonly used, but still impractical basic figure has been modified to more clearly demonstrate the response of the rotor for the harmonics of the stator. The need to treat differential leakage, asynchronous parasitic torques and attenuation together will be demonstrated: new formula for asynchronous parasitic torque is derived;the long-used characteristic curves for differential leakage and attenuation used separately so far was merged into one, correct curve in order to provide a correct design guide for the engineers.
文摘Human pose estimation(HPE)is a procedure for determining the structure of the body pose and it is considered a challenging issue in the computer vision(CV)communities.HPE finds its applications in several fields namely activity recognition and human-computer interface.Despite the benefits of HPE,it is still a challenging process due to the variations in visual appearances,lighting,occlusions,dimensionality,etc.To resolve these issues,this paper presents a squirrel search optimization with a deep convolutional neural network for HPE(SSDCNN-HPE)technique.The major intention of the SSDCNN-HPE technique is to identify the human pose accurately and efficiently.Primarily,the video frame conversion process is performed and pre-processing takes place via bilateral filtering-based noise removal process.Then,the EfficientNet model is applied to identify the body points of a person with no problem constraints.Besides,the hyperparameter tuning of the EfficientNet model takes place by the use of the squirrel search algorithm(SSA).In the final stage,the multiclass support vector machine(M-SVM)technique was utilized for the identification and classification of human poses.The design of bilateral filtering followed by SSA based EfficientNetmodel for HPE depicts the novelty of the work.To demonstrate the enhanced outcomes of the SSDCNN-HPE approach,a series of simulations are executed.The experimental results reported the betterment of the SSDCNN-HPE system over the recent existing techniques in terms of different measures.
文摘In data mining and machine learning,feature selection is a critical part of the process of selecting the optimal subset of features based on the target data.There are 2n potential feature subsets for every n features in a dataset,making it difficult to pick the best set of features using standard approaches.Consequently,in this research,a new metaheuristics-based feature selection technique based on an adaptive squirrel search optimization algorithm(ASSOA)has been proposed.When using metaheuristics to pick features,it is common for the selection of features to vary across runs,which can lead to instability.Because of this,we used the adaptive squirrel search to balance exploration and exploitation duties more evenly in the optimization process.For the selection of the best subset of features,we recommend using the binary ASSOA search strategy we developed before.According to the suggested approach,the number of features picked is reduced while maximizing classification accuracy.A ten-feature dataset from the University of California,Irvine(UCI)repository was used to test the proposed method’s performance vs.eleven other state-of-the-art approaches,including binary grey wolf optimization(bGWO),binary hybrid grey wolf and particle swarm optimization(bGWO-PSO),bPSO,binary stochastic fractal search(bSFS),binary whale optimization algorithm(bWOA),binary modified grey wolf optimization(bMGWO),binary multiverse optimization(bMVO),binary bowerbird optimization(bSBO),binary hybrid GWO and genetic algorithm 4028 CMC,2023,vol.74,no.2(bGWO-GA),binary firefly algorithm(bFA),and bGAmethods.Experimental results confirm the superiority and effectiveness of the proposed algorithm for solving the problem of feature selection.
文摘The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field,as well as the synchronous parasitic torques,radial magnetic forces have been discussed in great detail in the literature,but always separately,for a long time.However,systematization of the phenomenon still awaits.Therefore,it is worth summarizing the completeness of the phenomena in a single study–with a new approach at the same time-in order to reveal the relationships between them.The role of rotor slot number is emphasized much more than before.New formulas derived for both synchronous torques and radial magnetic forces are used for further investigation.It will be shown that both phenomena in subject must be treated together.Formulas will be provided to take into account attenuation.Design guide will be provided to avoid dangerous rotor slot numbers.It will be shown that the generation of synchronous torques and radial magnetic forces do not depend–in this new approach-on the slot combination,but on the rotor slot number itself.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program(STEP,2019QZKK0501)National Natural Science Foundation of China(32000304)+4 种基金Yunnan Fundamental Research Projects(202101AT070294)National Key Research and Development Program of China(2017YFC0505200)Strategic Priority Research Program of Chinese Academy of Sciences(XDA20050202)Biodiversity Survey,Monitoring and Assessment(2019HB2096001006)Kadoorie Farm&Botanic Garden。
文摘The flying squirrels(Pteromyini,Rodentia)are the most diverse and widely distributed group of gliding mammals.Taxonomic boundaries and relationships within flying squirrels remain an area of active research in mammalogy.The discovery of new specimens of Pteromys(Hylopetes)leonardi Thomas,1921,previously considered a synonym of Hylopetes alboniger,in Yunnan Province,China allowed a morphological and genetic reassessment of the status of this taxon.Phylogenetic reconstruction was implemented using sequences of two mitochondrial(12S ribosomal RNA and 16S ribosomal RNA)and one nuclear(interphotoreceptor retinoid-binding protein)gene fragments.Morphological assessments involved examinations of features preserved on skins,skulls,and penises of museum specimens,supplemented with principal component analysis of craniometric data.Together these assessments revealed that this taxon should be recognized not only as a distinct species,but should also be placed within a new genus,described here as Priapomys gen.nov.
文摘Urbanization of animal habitats has the potential to affect the natural communication systems of any species able to survive in the changed environment. Urban animals such as squirrels use multiple signal channels to communicate, but it is un- known how ttrbanization has affected these behaviors. Multimodal commtmication, involving more than one sensory modality, can be studied by use of biomimetic mechanical animal models that are designed to simulate the multimodal signals and be pre- sented to animal subjects in the field. In this way the responses to the various signal components can be compared and contrasted to determine whether the multimodal signal is made up of redundant or nonredundant components. In this study, we presented wild gray squirrels in relatively urban and relatively rural habitats in Western Massachusetts with a biomimetic squirrel model that produced tail flags and alarm barks in a variety of combinations. We found that the squirrels responded to each unimodal component on its own, the bark and tail flag, but they responded most to the complete multimodal signal, containing both the acoustic and the moving visual components, providing evidence that in this context the signal components are redundant and that their combination elicits multimodal enhancement. We expanded on the results of Partan et al. （2009） by providing data on sig- naling behavior in the presence and absence of conspecifics, suggesting that alarm signaling is more likely if conspecifics are present. We found that the squirrels were more active in the urban habitats and that they responded more to tail flagging in the urban habitats as compared to the rural ones, suggesting the interesting possibility of a multimodal shift from reliance on audio to visual signals in noisier more crowded urban habitats [Current Zoology 56 （3）： 313-326, 2010].
基金supported by the National High Technology Research and Development Program of China("863"Program)(Grant No.2009AA05Z207)
文摘To study the influence of skewed rotors and different skew angles on the losses of squirrel cage asynchronous motors,a 5.5-kW motor was taken as an example and the multi-sliced field-circuit coupled time stepping finite element method(T-S FEM)was used to analyze the axially non-uniform fundamental and harmonic field distribution characteristics at typical locations in the stator and rotor cores.The major conclusions are:firstly the skewed rotor exhibits a decrease in the harmonic copper losses caused by slot harmonic currents in the stator winding and rotor bars.Secondly,the skewed rotor shifts the non-uniform distribution of field in the axial direction,which leads to more severe saturation and an increase in iron losses.The heavier the load,the more pronounced the increase in iron losses.Furthermore,the influences of different skew angles on motor losses are studied systematically,with skew angles from 0.5 to 1.5 stator tooth pitch.It is found that the lowest total loss occurs at 0.8 stator tooth pitch,and the slot harmonics can be decreased effectively.
基金supported by the National Natural Science Foundation of China(31872320,21806010)the Young Scientist Start-up funding of Beijing Forestry University(BLX201714).
文摘The purpose of this study was to explore the variations in the circulating leptin concentrations of the wild ground squirrels in relation to seasonal changes in testicular activities.Hematoxylin-eosin staining showed all types of elongated spermatids and spermatogenic cells existed in the testis in April,while the primary spermatocytes and spermatogonia were most advanced stages of germ cells in June.In addition,the primary spermatocytes,secondary spermatocytes,and spermatogonia were most advanced stages of germ cells in September.The highest circulating leptin concentration was consistent with the maximum body weight results from accumulation of adipose tissue in September.The mRNA expression level of leptin receptor(Ob-R)and STAT3 was lowest in June,raised in September,and remained increased in April.Ob-R and STAT3 were stronger staining in the Leydig cells in July.Moreover,the concentrations of testosterone(T)showed the maximum values in April,the minimum values in June,and significant increases in September.Furthermore,it is worth noting that the levels of T increased with the mRNA levels of Ob-R,STAT3,StAR,and testicular steroidogenic enzymes(3β-HSD,P450c17,and P450scc).Moreover,RNA-seq analyses of testis during the different periods showed that a total of 4209 genes were differ-entially expressed genes(DEGs);further analysis revealed that DEGs related with the Jak/STAT pathways and reproduction were altered.Taken together,the results suggested that the leptin regulated testicular function through the Jak/STAT pathways and testicular steroidogenic factor expressions.
基金Sponsored by the Major State Basic Research Development Program of China(Grant No.2013CB632305)the National Natural Science Foundation of China(Grant No.51375108)
文摘To figure out the load distribution of thin-section rolling bearing supported by flexible structure with squirrel cage and the distribution's influence on bearing life,an iterative FEA method is proposed to use the result calculated from the Quasi-Dynamic model based on the rigid support hypothesis. The contact angle,contact position and stiffness of equivalent spring are modified during the iterative FEA to optimize the FEA model,and then the bearings' life can be predicted when the error is below 0.5%. It can be concluded that from the analysis results the load distribution under flexible support is more uniform than that of the rigid support,while the maximum load decreases by 11.2% and bearing life increases by 14.7%. The analysis result of different values of thickness of bearing house,rings and hollow shaft demonstrates the thicknesses of bearing house and hollow shaft have a greater influence on the load's uniformity and bearing's life than those of the rings.
文摘Inspired by creatures with membrane to obtain ultra-high gliding ability, this paper presents a robotic flying squirrel （a novel gliding robot） characterized as membrane wing and active membrane deformation. For deep understanding of membrane wing and gliding mechanism from a robotic system perspective, a simplified blocking aerodynamic model of the deformable membrane wing and CFD simulation are finished. In addition, a physical prototype is developed and wind tunnel experiments are carried out. The results show that the proposed membrane wing is able to support the gliding action of the robot. Meanwhile, factors including geometry characteristics, material property and wind speed are considered in the experiments to investigate the aerodynamic effects of the deformable membrane wing deeply. As a typical characteristic of robotic flying squirrel, deformation modes of the membrane wing not only affect the gliding ability, but also directly determine the effects of the posture adjustment. Moreover, different deformation modes of membrane wing are illustrated to explore the possible effects of active membrane deformation on the gliding performance. The results indicate that the deformation modes have a significant impact on posture adjustment, which reinforces the rationality of flying squirrel＇s gliding strategy and provides valuable information on prototype optimal design and control strategy in the actual gliding process.
