Collaborative changes in the hydro-sediment regime and erosional base level are vital factors that influence the evolution of wandering rivers.In the wandering Xiaobeiganliu reach of the Middle Yellow River(MYR),the r...Collaborative changes in the hydro-sediment regime and erosional base level are vital factors that influence the evolution of wandering rivers.In the wandering Xiaobeiganliu reach of the Middle Yellow River(MYR),the rapidly decreasing sediment discharge and lowering base level,i.e.,the Tongguan elevation,have resulted in new features of thalweg migration in river morphology.In this work,on the basis of topographic measurements of the reach from 2003–2021,the thalweg migration distance and intensity were calculated at both the section scale and reach scale.The results revealed that the annual sediment discharge decreased by 72%from 1986–2002,and the reach exhibited sustained scouring from deposition,leading to the Tongguan elevation decreasing by 1.69 m compared with that in 2002.Accordingly,the distance and intensity of thalweg migration have been reduced to varying degrees in both section and reach scales.The maximum section-scale thalweg migration distance was reduced by 11%,whereas the average thalweg migration distance and intensity at the reach scale decreased by 14%and 43%,respectively.During this sustained scouring period,the fluvial erosion intensity at the reach scale increased as the sediment discharge decreased.However,because the base level remained high,riverbed undercutting was deeply limited,which exacerbated lateral erosion of the bank and floodplain,enhancing thalweg migration.Flow-sediment regulation and training can be coupled to increase undercutting efficiency in the main channel and to protect banks from lateral erosion in river reach management.展开更多
In this paper,we study normal families of meromorphic functions.By using the idea in[16],we obtain some normality criteria for families of meromorphic functions concerning the wandering multiple functions,which extend...In this paper,we study normal families of meromorphic functions.By using the idea in[16],we obtain some normality criteria for families of meromorphic functions concerning the wandering multiple functions,which extend and improve the well-known Montel's criterion,Bloch-Valiron's theorem,and the related results due to Carathéodory,and Grahl-Nevo et al..展开更多
本文以“I Wandered Lonely as a Cloud”的辜正坤译本与杨德豫译本为研究对象,从意境、语音、语义及句法等维度展开对比分析。研究发现:在意境层面,辜译本用词典雅,杨译本忠实于原意;在语音层面,杨译本比辜译本更遵循原诗韵律;在语义...本文以“I Wandered Lonely as a Cloud”的辜正坤译本与杨德豫译本为研究对象,从意境、语音、语义及句法等维度展开对比分析。研究发现:在意境层面,辜译本用词典雅,杨译本忠实于原意;在语音层面,杨译本比辜译本更遵循原诗韵律;在语义与修辞层面,辜译本善用拟人、重复等手法增强诗意,且多使用动词,杨译本则侧重直译与形式对等,语言较为平实。二者的译本为诗歌翻译实践提供了多维启示。展开更多
Software defect prediction(SDP)aims to find a reliable method to predict defects in specific software projects and help software engineers allocate limited resources to release high-quality software products.Software ...Software defect prediction(SDP)aims to find a reliable method to predict defects in specific software projects and help software engineers allocate limited resources to release high-quality software products.Software defect prediction can be effectively performed using traditional features,but there are some redundant or irrelevant features in them(the presence or absence of this feature has little effect on the prediction results).These problems can be solved using feature selection.However,existing feature selection methods have shortcomings such as insignificant dimensionality reduction effect and low classification accuracy of the selected optimal feature subset.In order to reduce the impact of these shortcomings,this paper proposes a new feature selection method Cubic TraverseMa Beluga whale optimization algorithm(CTMBWO)based on the improved Beluga whale optimization algorithm(BWO).The goal of this study is to determine how well the CTMBWO can extract the features that are most important for correctly predicting software defects,improve the accuracy of fault prediction,reduce the number of the selected feature and mitigate the risk of overfitting,thereby achieving more efficient resource utilization and better distribution of test workload.The CTMBWO comprises three main stages:preprocessing the dataset,selecting relevant features,and evaluating the classification performance of the model.The novel feature selection method can effectively improve the performance of SDP.This study performs experiments on two software defect datasets(PROMISE,NASA)and shows the method’s classification performance using four detailed evaluation metrics,Accuracy,F1-score,MCC,AUC and Recall.The results indicate that the approach presented in this paper achieves outstanding classification performance on both datasets and has significant improvement over the baseline models.展开更多
In this paper,we obtain a normality criterion for families of meromorphic functions concerning‘wandering’shared functions,which generalizes and improves Montel’s criterion and the related results due to Schwick,Xu-...In this paper,we obtain a normality criterion for families of meromorphic functions concerning‘wandering’shared functions,which generalizes and improves Montel’s criterion and the related results due to Schwick,Xu-Fang,Xu-Qiu,and Grahl-Nevo.Also,a normality relationship between two families is given.展开更多
The reference-frame-independent(RFI)quantum key distribution(QKD)is suitable for satellite-based links by removing the active alignment on the reference frames.However,how the beam wandering influences the performance...The reference-frame-independent(RFI)quantum key distribution(QKD)is suitable for satellite-based links by removing the active alignment on the reference frames.However,how the beam wandering influences the performance of RFI-QKD remains a pending issue in satellite-to-ground links.In this paper,based on the mathematical model for characterizing beam wandering,we present the security analysis for satellite-to-ground RFI-QKD and analytically derive formulas for calculating the secret key rate with beam wandering.Our simulation results show that the performance of RFI-QKD is better than the Bennett–Brassard 1984(BB84)QKD with beam wandering in asymptotic case.Furthermore,the degree of influences of beam wandering is specifically presented for satellite-to-ground RFI-QKD when statistical fluctuations are taken into account.Our work can provide theoretical support for the realization of RFI-QKD using satellite-to-ground links and have implications for the construction of large-scale satellite-based quantum networks.展开更多
In this paper,we consider entire solutions of higher order homogeneous differential equations with the entire coefficients having the same order,and prove that the entire solutions are of infinite lower order.The prop...In this paper,we consider entire solutions of higher order homogeneous differential equations with the entire coefficients having the same order,and prove that the entire solutions are of infinite lower order.The properties on the radial distribution,the limit direction of the Julia set and the existence of a Baker wandering domain of the entire solutions are also discussed.展开更多
This experimental study investigated how text difficulty and different working memory capacity(WMC)affected Chinese EFL learners’reading comprehension and their tendency to engage in task-unrelated thoughts,that is,m...This experimental study investigated how text difficulty and different working memory capacity(WMC)affected Chinese EFL learners’reading comprehension and their tendency to engage in task-unrelated thoughts,that is,mind wandering(MW),in the course of reading.Sixty first-year university non-English majors participated in the study.A two-factor mixed experimental design of 2(text difficulty:difficult and simple)×2(WMC:high/large and low/small)was employed.Results revealed that 1)the main and interaction effects of WMC and text difficulty on voluntary MW were significant,whereas those on involuntary MW were not;2)while reading the easy texts,the involuntary MW of high-WMC individuals was less frequent than that of low-WMC ones,whereas while reading the difficult ones,the direct relationship between WMC and involuntary MW was not found;and that 3)high-WMC individuals had a lower overall rate of MW and better reading performance than low-WMC individuals did,but with increasing text difficulty,their rates of overall MW and voluntary MW were getting higher and higher,and the reading performance was getting lower and lower.These results lend support to WM theory and have pedagogical implications for the instruction of L2 reading.展开更多
BACKGROUNDWith the incidence of pancreatic diseases increasing year by year,pancreatichyperglycemia,as one of the common complications,is gradually gaining attentionfor its impact on the skin health of patients.CASE S...BACKGROUNDWith the incidence of pancreatic diseases increasing year by year,pancreatichyperglycemia,as one of the common complications,is gradually gaining attentionfor its impact on the skin health of patients.CASE SUMMARYThis was the case of an elderly female with clinical manifestations of necrolyticmigratory erythema,“three more and one less,”diabetes mellitus,hypertension,anemia,hypoproteinemia,and other syndromes,which had been misdiagnosedas eczema.Abdominal computed tomography showed a pancreatic caudal spaceoccupyinglesion,and the magnetic resonance scanning of the epigastric regionwith dynamic enhancement and diffusion-weighted imaging suggested a tumorof the pancreatic tail,which was considered to be a neuroendocrine tumor orcystadenoma.The patient was referred to a more equipped hospital for laparoscopicpancreatic tail resection.Post-surgery diagnosis revealed a neuroendocrinetumor in the tail of the pancreas.To date,the patient’s general condition is good,and she is still under close follow-up.CONCLUSIONNecrolytic migratory erythema can be induced by endocrine system tumors orendocrine metabolic abnormalities,with complex clinical manifestations,difficultdiagnosis,and easy misdiagnosis by dermatologists.The initial treatment principlesin dermatology include symptomatic supportive therapy and effectivedrugs to relieve skin lesions.After clarifying the etiology of glucagonoma,comprehensive treatment in collaboration with endocrinologists,generalsurgeons,and oncologists can help provide individualized treatment for patientsand improve their prognosis.展开更多
This paper is centered on the extent to which contemporary Chinese science fiction is related to ancient Chinese mythologies according to the previous scholarly discussion and how these ancient mythologies are utilize...This paper is centered on the extent to which contemporary Chinese science fiction is related to ancient Chinese mythologies according to the previous scholarly discussion and how these ancient mythologies are utilized specifically in the futuristic narratives of modern Chinese science fiction.By referring to academic dialogues,this paper argues that ancient mythologies can be recreated in modern science fiction and create modern mythologies in futuristic narratives to present or deal with modern human fears.Based on this argument,this paper then continues to explore what kinds of modern mythologies science fiction might deliver.The Chinese film The Wandering Earth(2019)will be discussed in terms of its mythological symbols and metaphors.This paper proposes a new approach through which to reconnect past stories with futuristic narratives and builds a frame in which to contextualize ancient mythologies in contemporary Chinese culture.展开更多
A frequency-domain equalizer with a mixed-signal adaptive control loop and a novel baseline wander （BLW） canceller are proposed. The equalizer is independent of channel-modeling accuracy,and its control loop is intr...A frequency-domain equalizer with a mixed-signal adaptive control loop and a novel baseline wander （BLW） canceller are proposed. The equalizer is independent of channel-modeling accuracy,and its control loop is intrinsically stable. An AGC function is incorporated into the equalizer without an extra AGC circuit. The proposed BLW canceller uses a peak detector to monitor the BLW and full feedback method to accomplish BLW canceling. High canceling accuracy and robust performance are achieved. The circuits are tested in 0.25μm CMOS technology. Better performance and smaller silicon area are achieved compared with results in the literature.展开更多
By using wave optics numerical simulation, the intensity-hole effect, beam spreading and wandering properties of Gaussian vortex beam propagation in atmospheric turbulence are investigated quantitatively. It is found ...By using wave optics numerical simulation, the intensity-hole effect, beam spreading and wandering properties of Gaussian vortex beam propagation in atmospheric turbulence are investigated quantitatively. It is found that an intensity hole in the center of the beam pattern appears gradually as a Gaussian vortex beam propagates. The size of the intensity hole increases with the increase of the topological charge of the vortex phase. However, the intensity hole could to some extent be filled with optical energy by atmospheric turbulence, especially in strong turbulence. The radius of the intensity hole first decreases and then increases with the growth of turbulence strength. The effective radius of vortex beam with larger topological charge is greater than with a smaller topological charge. But the topological charge has no evident influence on beam wandering.展开更多
Evolution of the river channel downstream of reservoirs is a complex process that is closely related to the operational mode of the reservoirs and the channel boundary conditions Numerous studies have been carried out...Evolution of the river channel downstream of reservoirs is a complex process that is closely related to the operational mode of the reservoirs and the channel boundary conditions Numerous studies have been carried out on the fluvial processes of downstream reservoirs. However, only a few of them have focused on the relationship between runoff-sediment con- ditions and channel pattern indicators. Also, the impacts of river training works on fluvial processes are seldom dealt with. In this paper, the evolutionary processes of three sections in the Lower Yellow River, including Tiexie-Yiluo River mouth reach, Huayuankou-Heigangkou reach and Jiahetan-Gaocun reach, were analyzed for variations in the channel boundary line and the mainstream between 1960 and 2015. Channel pattern indicators such as sinuosity, mainstream wandering range and width/depth ratio were analyzed based on field measure- ments obtained by the Hydrological Department of the Yellow River Conservancy Commis- sion. The effects of river training works on the channel evolution are then described. Since 1960, numerous medium- and large-sized reservoirs have been built on the Yellow River, including Longyangxia Reservoir, Liujiaxia Reservoir and Xiaolangdi Reservoir. These res- ervoirs impound the runoff from upstream and retain the sediment, which changes the runoff and sediment conditions in the downstream reach. As a consequence, annual runoff and the frequency and peak of flooding have all decreased. As a result, the flow dynamics and their action on the river channel are also reduced, which changes the dynamic state of the river course. The discrimination results obtained using the single parameter discrimination rule and the discrimination equation show that the degree of wandering is weakened in the reaches studied. The variations in the channel pattern indicators show that the sinuosity in- creases and the wandering range decreases with a reduction in the total annual volume of water. However, the degree of wandering has little relationship to the sediment concentration. In addition, river training works play an important role in controlling the river course. Due to improvements in the river training works, the river course has become more stable under the same runoff and sediment conditions. A new discrimination rule that takes into account the impacts of the river training works is proposed. The discrimination results were found to fit well with the actual river pattern, which shows that the discrimination rule is applicable to the Lower Yellow River. The results show that the runoff and sediment conditions are the most important factors in the evolution of the river course. The river training works have at the same time limited the wandering range of the mainstream and played an important role in the fluvial processes. Both factors combined lead to the stabilization of the river.展开更多
In this paper, we mainly investigate entire solutions of complex differential equations with coefficients involving exponential functions, and obtain the dynamical properties of the solutions, their derivatives and pr...In this paper, we mainly investigate entire solutions of complex differential equations with coefficients involving exponential functions, and obtain the dynamical properties of the solutions, their derivatives and primitives. With some conditions on coefficients, for the solutions, their derivatives and their primitives, we consider the common limiting directions of Julia set and the existence of Baker wandering domain.展开更多
Mid-Cretaceous strata within the Tintina Trench, 3 km west of the community of Ross River, contain evidence of deposition in two distinct, alternating, fluvial settings. Coal-bearing, mud-dominated strata are commonly...Mid-Cretaceous strata within the Tintina Trench, 3 km west of the community of Ross River, contain evidence of deposition in two distinct, alternating, fluvial settings. Coal-bearing, mud-dominated strata are commonly associated with high-constructive sandy channel systems, with extensive overbank, levee and splay deposits. Channels are between 3 and 30 m wide and 0.4-7 m thick. They show repetitive development of side and in-channel bar-forms, as well as up-channel widening of the rivers by selective erosion of associated overbank and levee deposits. Levees extended for several hundred metres away from the channels. In this setting low-angle inclined stratification and epsilon cross stratification may reflect lateral migration of crevasse channels or small streams. The paucity of exposure prevents recognition of the channels as products of multiple channel anastomosed systems or single channel high-constructive systems. Gravel-dominated strata, inter-bedded with, and overlying coal-bearing units, are interpreted as deposits of wandering gravel-bed rivers, with sinuosity approaching 1.4. In most exposures they appear to be dominated by massive and thin planar-bedded granule to small pebble conglomerates, which would traditionally be interpreted as sheet-flood or longitudinal bar deposits of a high-gradient braided stream or alluvial fan. Architectural analysis of exposures in an open-pit shows that the predominance of flat bedding is an artefact of the geometry of the roadside exposures. In the pit the conglomerates are dominated by large scale cross stratification on a scale of 1-5.5 m. These appear to have developed as downstream and lateral accretion elements on side-bars and on in-channel bars in water depths of 2-12 m. Stacking of strata on domed 3rd order surfaces suggests development of longitudinal in-channel bar complexes similar to those observed in parts of the modern Rhone River system. Mudstone preserved in some of the channels reflects intervals of channel abandonment or avulsion. Minimum channel width is from 70 to 450 m.展开更多
基金National Key R&D Program of China,No.2023YFC3206205National Natural Science Foundation of China,No.U22A20237Independent Research Project of Yellow River Engineering Consulting Co.,Ltd.,No.2025KY001。
文摘Collaborative changes in the hydro-sediment regime and erosional base level are vital factors that influence the evolution of wandering rivers.In the wandering Xiaobeiganliu reach of the Middle Yellow River(MYR),the rapidly decreasing sediment discharge and lowering base level,i.e.,the Tongguan elevation,have resulted in new features of thalweg migration in river morphology.In this work,on the basis of topographic measurements of the reach from 2003–2021,the thalweg migration distance and intensity were calculated at both the section scale and reach scale.The results revealed that the annual sediment discharge decreased by 72%from 1986–2002,and the reach exhibited sustained scouring from deposition,leading to the Tongguan elevation decreasing by 1.69 m compared with that in 2002.Accordingly,the distance and intensity of thalweg migration have been reduced to varying degrees in both section and reach scales.The maximum section-scale thalweg migration distance was reduced by 11%,whereas the average thalweg migration distance and intensity at the reach scale decreased by 14%and 43%,respectively.During this sustained scouring period,the fluvial erosion intensity at the reach scale increased as the sediment discharge decreased.However,because the base level remained high,riverbed undercutting was deeply limited,which exacerbated lateral erosion of the bank and floodplain,enhancing thalweg migration.Flow-sediment regulation and training can be coupled to increase undercutting efficiency in the main channel and to protect banks from lateral erosion in river reach management.
文摘In this paper,we study normal families of meromorphic functions.By using the idea in[16],we obtain some normality criteria for families of meromorphic functions concerning the wandering multiple functions,which extend and improve the well-known Montel's criterion,Bloch-Valiron's theorem,and the related results due to Carathéodory,and Grahl-Nevo et al..
文摘本文以“I Wandered Lonely as a Cloud”的辜正坤译本与杨德豫译本为研究对象,从意境、语音、语义及句法等维度展开对比分析。研究发现:在意境层面,辜译本用词典雅,杨译本忠实于原意;在语音层面,杨译本比辜译本更遵循原诗韵律;在语义与修辞层面,辜译本善用拟人、重复等手法增强诗意,且多使用动词,杨译本则侧重直译与形式对等,语言较为平实。二者的译本为诗歌翻译实践提供了多维启示。
文摘Software defect prediction(SDP)aims to find a reliable method to predict defects in specific software projects and help software engineers allocate limited resources to release high-quality software products.Software defect prediction can be effectively performed using traditional features,but there are some redundant or irrelevant features in them(the presence or absence of this feature has little effect on the prediction results).These problems can be solved using feature selection.However,existing feature selection methods have shortcomings such as insignificant dimensionality reduction effect and low classification accuracy of the selected optimal feature subset.In order to reduce the impact of these shortcomings,this paper proposes a new feature selection method Cubic TraverseMa Beluga whale optimization algorithm(CTMBWO)based on the improved Beluga whale optimization algorithm(BWO).The goal of this study is to determine how well the CTMBWO can extract the features that are most important for correctly predicting software defects,improve the accuracy of fault prediction,reduce the number of the selected feature and mitigate the risk of overfitting,thereby achieving more efficient resource utilization and better distribution of test workload.The CTMBWO comprises three main stages:preprocessing the dataset,selecting relevant features,and evaluating the classification performance of the model.The novel feature selection method can effectively improve the performance of SDP.This study performs experiments on two software defect datasets(PROMISE,NASA)and shows the method’s classification performance using four detailed evaluation metrics,Accuracy,F1-score,MCC,AUC and Recall.The results indicate that the approach presented in this paper achieves outstanding classification performance on both datasets and has significant improvement over the baseline models.
基金Supported by the National Natural Science Foundation of China(Grant No.11471163)。
文摘In this paper,we obtain a normality criterion for families of meromorphic functions concerning‘wandering’shared functions,which generalizes and improves Montel’s criterion and the related results due to Schwick,Xu-Fang,Xu-Qiu,and Grahl-Nevo.Also,a normality relationship between two families is given.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.61505261,62101597,61605248,and 61675235)the National Key Research and Development Program of China (Grant No.2020YFA0309702)+2 种基金the China Postdoctoral Science Foundation (Grant No.2021M691536)the Natural Science Foundation of Henan Province,China (Grant Nos.202300410534 and 202300410532)the Fund of the Anhui Initiative in Quantum Information Technologies。
文摘The reference-frame-independent(RFI)quantum key distribution(QKD)is suitable for satellite-based links by removing the active alignment on the reference frames.However,how the beam wandering influences the performance of RFI-QKD remains a pending issue in satellite-to-ground links.In this paper,based on the mathematical model for characterizing beam wandering,we present the security analysis for satellite-to-ground RFI-QKD and analytically derive formulas for calculating the secret key rate with beam wandering.Our simulation results show that the performance of RFI-QKD is better than the Bennett–Brassard 1984(BB84)QKD with beam wandering in asymptotic case.Furthermore,the degree of influences of beam wandering is specifically presented for satellite-to-ground RFI-QKD when statistical fluctuations are taken into account.Our work can provide theoretical support for the realization of RFI-QKD using satellite-to-ground links and have implications for the construction of large-scale satellite-based quantum networks.
基金supported partly by the National Natural Science Foundation of China(11926201,12171050)the National Science Foundation of Guangdong Province(2018A030313508)。
文摘In this paper,we consider entire solutions of higher order homogeneous differential equations with the entire coefficients having the same order,and prove that the entire solutions are of infinite lower order.The properties on the radial distribution,the limit direction of the Julia set and the existence of a Baker wandering domain of the entire solutions are also discussed.
文摘This experimental study investigated how text difficulty and different working memory capacity(WMC)affected Chinese EFL learners’reading comprehension and their tendency to engage in task-unrelated thoughts,that is,mind wandering(MW),in the course of reading.Sixty first-year university non-English majors participated in the study.A two-factor mixed experimental design of 2(text difficulty:difficult and simple)×2(WMC:high/large and low/small)was employed.Results revealed that 1)the main and interaction effects of WMC and text difficulty on voluntary MW were significant,whereas those on involuntary MW were not;2)while reading the easy texts,the involuntary MW of high-WMC individuals was less frequent than that of low-WMC ones,whereas while reading the difficult ones,the direct relationship between WMC and involuntary MW was not found;and that 3)high-WMC individuals had a lower overall rate of MW and better reading performance than low-WMC individuals did,but with increasing text difficulty,their rates of overall MW and voluntary MW were getting higher and higher,and the reading performance was getting lower and lower.These results lend support to WM theory and have pedagogical implications for the instruction of L2 reading.
文摘BACKGROUNDWith the incidence of pancreatic diseases increasing year by year,pancreatichyperglycemia,as one of the common complications,is gradually gaining attentionfor its impact on the skin health of patients.CASE SUMMARYThis was the case of an elderly female with clinical manifestations of necrolyticmigratory erythema,“three more and one less,”diabetes mellitus,hypertension,anemia,hypoproteinemia,and other syndromes,which had been misdiagnosedas eczema.Abdominal computed tomography showed a pancreatic caudal spaceoccupyinglesion,and the magnetic resonance scanning of the epigastric regionwith dynamic enhancement and diffusion-weighted imaging suggested a tumorof the pancreatic tail,which was considered to be a neuroendocrine tumor orcystadenoma.The patient was referred to a more equipped hospital for laparoscopicpancreatic tail resection.Post-surgery diagnosis revealed a neuroendocrinetumor in the tail of the pancreas.To date,the patient’s general condition is good,and she is still under close follow-up.CONCLUSIONNecrolytic migratory erythema can be induced by endocrine system tumors orendocrine metabolic abnormalities,with complex clinical manifestations,difficultdiagnosis,and easy misdiagnosis by dermatologists.The initial treatment principlesin dermatology include symptomatic supportive therapy and effectivedrugs to relieve skin lesions.After clarifying the etiology of glucagonoma,comprehensive treatment in collaboration with endocrinologists,generalsurgeons,and oncologists can help provide individualized treatment for patientsand improve their prognosis.
文摘This paper is centered on the extent to which contemporary Chinese science fiction is related to ancient Chinese mythologies according to the previous scholarly discussion and how these ancient mythologies are utilized specifically in the futuristic narratives of modern Chinese science fiction.By referring to academic dialogues,this paper argues that ancient mythologies can be recreated in modern science fiction and create modern mythologies in futuristic narratives to present or deal with modern human fears.Based on this argument,this paper then continues to explore what kinds of modern mythologies science fiction might deliver.The Chinese film The Wandering Earth(2019)will be discussed in terms of its mythological symbols and metaphors.This paper proposes a new approach through which to reconnect past stories with futuristic narratives and builds a frame in which to contextualize ancient mythologies in contemporary Chinese culture.
文摘A frequency-domain equalizer with a mixed-signal adaptive control loop and a novel baseline wander （BLW） canceller are proposed. The equalizer is independent of channel-modeling accuracy,and its control loop is intrinsically stable. An AGC function is incorporated into the equalizer without an extra AGC circuit. The proposed BLW canceller uses a peak detector to monitor the BLW and full feedback method to accomplish BLW canceling. High canceling accuracy and robust performance are achieved. The circuits are tested in 0.25μm CMOS technology. Better performance and smaller silicon area are achieved compared with results in the literature.
基金Project supported by the National Natural Science Foundation of China(Grant No.61107066)
文摘By using wave optics numerical simulation, the intensity-hole effect, beam spreading and wandering properties of Gaussian vortex beam propagation in atmospheric turbulence are investigated quantitatively. It is found that an intensity hole in the center of the beam pattern appears gradually as a Gaussian vortex beam propagates. The size of the intensity hole increases with the increase of the topological charge of the vortex phase. However, the intensity hole could to some extent be filled with optical energy by atmospheric turbulence, especially in strong turbulence. The radius of the intensity hole first decreases and then increases with the growth of turbulence strength. The effective radius of vortex beam with larger topological charge is greater than with a smaller topological charge. But the topological charge has no evident influence on beam wandering.
文摘Evolution of the river channel downstream of reservoirs is a complex process that is closely related to the operational mode of the reservoirs and the channel boundary conditions Numerous studies have been carried out on the fluvial processes of downstream reservoirs. However, only a few of them have focused on the relationship between runoff-sediment con- ditions and channel pattern indicators. Also, the impacts of river training works on fluvial processes are seldom dealt with. In this paper, the evolutionary processes of three sections in the Lower Yellow River, including Tiexie-Yiluo River mouth reach, Huayuankou-Heigangkou reach and Jiahetan-Gaocun reach, were analyzed for variations in the channel boundary line and the mainstream between 1960 and 2015. Channel pattern indicators such as sinuosity, mainstream wandering range and width/depth ratio were analyzed based on field measure- ments obtained by the Hydrological Department of the Yellow River Conservancy Commis- sion. The effects of river training works on the channel evolution are then described. Since 1960, numerous medium- and large-sized reservoirs have been built on the Yellow River, including Longyangxia Reservoir, Liujiaxia Reservoir and Xiaolangdi Reservoir. These res- ervoirs impound the runoff from upstream and retain the sediment, which changes the runoff and sediment conditions in the downstream reach. As a consequence, annual runoff and the frequency and peak of flooding have all decreased. As a result, the flow dynamics and their action on the river channel are also reduced, which changes the dynamic state of the river course. The discrimination results obtained using the single parameter discrimination rule and the discrimination equation show that the degree of wandering is weakened in the reaches studied. The variations in the channel pattern indicators show that the sinuosity in- creases and the wandering range decreases with a reduction in the total annual volume of water. However, the degree of wandering has little relationship to the sediment concentration. In addition, river training works play an important role in controlling the river course. Due to improvements in the river training works, the river course has become more stable under the same runoff and sediment conditions. A new discrimination rule that takes into account the impacts of the river training works is proposed. The discrimination results were found to fit well with the actual river pattern, which shows that the discrimination rule is applicable to the Lower Yellow River. The results show that the runoff and sediment conditions are the most important factors in the evolution of the river course. The river training works have at the same time limited the wandering range of the mainstream and played an important role in the fluvial processes. Both factors combined lead to the stabilization of the river.
基金supported by Shanghai Center for Mathematical Science China Scholarship Council(201206105015)the National Science Foundation of China(11171119,11001057,11571049)the Natural Science Foundation of Guangdong Province in China(2014A030313422)
文摘In this paper, we mainly investigate entire solutions of complex differential equations with coefficients involving exponential functions, and obtain the dynamical properties of the solutions, their derivatives and primitives. With some conditions on coefficients, for the solutions, their derivatives and their primitives, we consider the common limiting directions of Julia set and the existence of Baker wandering domain.
基金NSERC,Lithoprobe(Snorcle) and the Government of the Yukon for providing support for this research
文摘Mid-Cretaceous strata within the Tintina Trench, 3 km west of the community of Ross River, contain evidence of deposition in two distinct, alternating, fluvial settings. Coal-bearing, mud-dominated strata are commonly associated with high-constructive sandy channel systems, with extensive overbank, levee and splay deposits. Channels are between 3 and 30 m wide and 0.4-7 m thick. They show repetitive development of side and in-channel bar-forms, as well as up-channel widening of the rivers by selective erosion of associated overbank and levee deposits. Levees extended for several hundred metres away from the channels. In this setting low-angle inclined stratification and epsilon cross stratification may reflect lateral migration of crevasse channels or small streams. The paucity of exposure prevents recognition of the channels as products of multiple channel anastomosed systems or single channel high-constructive systems. Gravel-dominated strata, inter-bedded with, and overlying coal-bearing units, are interpreted as deposits of wandering gravel-bed rivers, with sinuosity approaching 1.4. In most exposures they appear to be dominated by massive and thin planar-bedded granule to small pebble conglomerates, which would traditionally be interpreted as sheet-flood or longitudinal bar deposits of a high-gradient braided stream or alluvial fan. Architectural analysis of exposures in an open-pit shows that the predominance of flat bedding is an artefact of the geometry of the roadside exposures. In the pit the conglomerates are dominated by large scale cross stratification on a scale of 1-5.5 m. These appear to have developed as downstream and lateral accretion elements on side-bars and on in-channel bars in water depths of 2-12 m. Stacking of strata on domed 3rd order surfaces suggests development of longitudinal in-channel bar complexes similar to those observed in parts of the modern Rhone River system. Mudstone preserved in some of the channels reflects intervals of channel abandonment or avulsion. Minimum channel width is from 70 to 450 m.
