The Menyuan Basin is a structural basin located inside the Qilianshan Mountains, the northern edge of Qinghai—Tibet Plateau, the surface of which is about 3000m ASL. To the south of this basin is the Dabanshan Mounta...The Menyuan Basin is a structural basin located inside the Qilianshan Mountains, the northern edge of Qinghai—Tibet Plateau, the surface of which is about 3000m ASL. To the south of this basin is the Dabanshan Mountain and to the north, the Lenglongling Mountain, which are 4000m ASL.. The neotectonic movement within this area is intense and can be divided into 6 stages.1 The basic data for identifying the stages of the neotectonic movement (1) Deformation of Tertiary deposit: Of the Tertiary system, only Baiyanghe Formation exists in the studied area, distributing at the boundary and under the bottom of the basin with Quaternary deposits discontinuously overlying it. Baiyanghe Formation has been intensely offset and folded, the folding dose not appear in Quaternary deposits. Its exact age remains unknown.(2) Deformation of Quaternary deposits: Most of Quaternary deposits belong to glacial and fluvial deposits, which have been offset and uplifted or sunk by neotectonic movement.(3) Deformation of the geomorphic surfaces: In the studied area exist many types and many orders of geomorphic surfaces, including 2 orders of planation surfaces, 3 orders of glacial platforms, 3 orders of river terraces and 2 orders of alluvial fans. Their ages are dated or comparatively estimated. All of them have been offset and uplifted or subsided by neotectonic movement. They are the time scales for dividing the stages of neotectonic movement.展开更多
Ⅰ. INTRODUCTION How to teach listening comprehension in the classroom tends to get neglec-ted altegther. This is because an English teacher saw the need for givinghis students praetice but failed to take account of s...Ⅰ. INTRODUCTION How to teach listening comprehension in the classroom tends to get neglec-ted altegther. This is because an English teacher saw the need for givinghis students praetice but failed to take account of several important things,such as: (1)Texts should not be so difficult. As it is, they are almest alwaysabeve the level of the students. (2)Students should not be asked to remember everything they hear. (3)Students should be given guided practice to learn to take notes. (4)The teachor should relate their listening practice to the real-lifesituations in which the students would actually want to use the skill.展开更多
Electric submersible pumps were widely used in agricultural fields,petroleum and various other industries. The pressure pulsation caused fatigue failure due to vibration in electric submersible pump and affects the li...Electric submersible pumps were widely used in agricultural fields,petroleum and various other industries. The pressure pulsation caused fatigue failure due to vibration in electric submersible pump and affects the life and performance of its system. The objective of this study was to experimentally investigate the characteristics of pressure pulsation which were generated at various stages of a multistage electric submersible pump during closed valve operation at different speeds. An electric submersible pump with five stages was selected for conducting experiments. A variable frequency drive( VFD)was used to operate the electric submersible pump at five different speed settings from 40 to 60 Hz. Piezoresistive pressure transducers were mounted at each stage of the electric submersible pump to capture the unsteady pressure signals. At each speed setting,the electric submersible pump was operated at the shut-off condition and the signals of unsteady pressure from all the five stages were captured. A fast fourier transformation( FFT) was carried out on the pressure signals to convert into frequency domain.From the spectra of pressure pulsation signals,the characteristics of pressure pulsation are obtained for each stage and for various speed settings which were then used to understand its variation with speed and stages.展开更多
Blaptostethus pallescens Poppius (Heteroptera:Anthocoridae),which is amenable to mass rearing,has proved to be a potential predator of sucking pests like mites and thrips.Recently,the cotton mealybug Phenacoccus solen...Blaptostethus pallescens Poppius (Heteroptera:Anthocoridae),which is amenable to mass rearing,has proved to be a potential predator of sucking pests like mites and thrips.Recently,the cotton mealybug Phenacoccus solenopsis Tinsley emerged as a serious pest on cotton in India.Laboratory studies indicated that B.pallescens could feed on the cotton mealybug.Hence,further investigations were conducted to understand the stage of the predator which is most potential and the pest stage preferred by the predator.Mature nymphs and adults of B.pallescens could predate equally well on the neonates of cotton mealybug.Young (three to four-day-old) nymphs of the predator could not feed on any stage of the cotton mealybug.Mature nymphs (seven-day-old and above) and adults could effectively predate on both young and mature cotton mealybug crawlers,though preference was more for the younger crawlers.However,nymphs and adults of B.pallescens could not predate on the adult stage of the mealybug.Different predator:pest ratios were tested in cage studies and it emerged that B.pallescens adults released against the mealybug crawlers at a ratio of 1:5 and nymphal release at 1:10 caused maximum mortality of the mealybug crawlers.Considering the fast multiplication rate of cotton mealybug and the large number of predators which have to be released to manage them,further detailed studies are necessary on utilizing B.pallescens to target the neonates and younger stages of the cotton mealybug in field conditions.展开更多
Heracleum dissectum Ledeb.(HD)with high edible and medicinal values is distributed in Northeast Asia.To provide a reference for selecting appropriate parts and periods to harvest HD,the nutrient contents in different ...Heracleum dissectum Ledeb.(HD)with high edible and medicinal values is distributed in Northeast Asia.To provide a reference for selecting appropriate parts and periods to harvest HD,the nutrient contents in different parts of HD at three growth stages were determined.The nutrients being determined are essential nutrients closely related to human needs,and the crude protein content of HD was 3.58‒28.43 g•100 g^(-1)DW(dry weight),sugar content was 2.33‒30.92 g•100 g^(-1)DW,and soluble dietary fiber content was 9.71‒26.09 g•100 g^(-1)DW.Crude protein was mainly distributed in leaf blades and inflorescences,sugar was primarily found in roots,and dietary fiber was predominantly located in leaves.From the leaf development stage to the flowering stage and then to the late seed harvest stage,the content of moisture,crude protein and soluble sugar first decreased and then increased.In contrast,the content of dietary fiber and crude fat first increased and then decreased.展开更多
Water is a critical factor affecting the mechanical properties of rocks, leading to their degradation. Understanding the creep mechanical behavior of deep roadway surrounding rock under the influence of underground wa...Water is a critical factor affecting the mechanical properties of rocks, leading to their degradation. Understanding the creep mechanical behavior of deep roadway surrounding rock under the influence of underground water is of great significance. Compression and creep experiments on sandstone with varying water contents were conducted using a deep soft rock five-linked rheological experiment system. The experimental conditions, including water content (0%, 0.8%, 1.6%, 2.4% and 3.3%) and confining pressure (0, 6, 9 and 12 MPa), were determined based on pressure-free water absorption tests and in-situ stress measurements. The experimental results show that the compressive strength, creep failure stress, and dilatancy stress of sandstone decrease exponentially with increasing water content, while they increase exponentially with confining pressure. The ratio of lateral to axial instantaneous strain increases nearly linearly with the increase of stress, and the lateral creep strain characteristics of the sample are more significant than the axial ones. The duration of the attenuation creep stage of sandstone decreases with increasing water content and increases with increasing confining pressure. The lateral strain enters the steady-state creep stage before the axial strain, and the onset time of the accelerated creep stage of lateral strain under the failure stress is earlier than that of axial strain. The long-term strength of sandstone was determined based on the lateral steady-state creep rate curve, showing a negative exponential relationship with water content and a positive exponential relationship with confining pressure. A method for determining the long-term strength of rocks based on the ratio of lateral strain to axial strain (μc) is proposed, which is independent of water content. The research results provide a reliable theoretical basis for the analysis of the long-term stability of roadways under the influence of groundwater and the early prediction of creep failure.展开更多
基于重复轨道航天飞机SIR-C的L和C波段极化干涉雷达数据,提出了一种将三阶段反演方法(Three-Stage Inversion)和ESPRIT(Estimation of Signal Parameters via Rotational Invariance Techniques)算法相结合的新的相位基植被高度估计方法...基于重复轨道航天飞机SIR-C的L和C波段极化干涉雷达数据,提出了一种将三阶段反演方法(Three-Stage Inversion)和ESPRIT(Estimation of Signal Parameters via Rotational Invariance Techniques)算法相结合的新的相位基植被高度估计方法.首先,基于L波段极化干涉数据,用三阶段反演方法获取植被覆盖地表下地形有效散射中心的相位;接着,基于C波段极化干涉数据,用ESPRIT算法估计植被冠层有效散射中心的相位;最后,对二者的相位差进行相位到高度的转换得到植被的高度.根据研究区域的实测林相数据,对该算法估计的植被高度结果进行了比较和验证,结果表明:该方法具有足够高的植被高度估计精度,如果能得到P和X波段的双频极化干涉雷达数据,该方法估计植被高度的精度将会得到进一步的提高.展开更多
在对无人机作战特点及使用样式深入研究的基础上,综合运用STAGE(scenario toolkit and generation environment)仿真软件,给出以HLA为核心的无人机作战仿真系统框架,构建无人机和导弹等关键实体扩展模型,开发了战场仿真环境。结合无人...在对无人机作战特点及使用样式深入研究的基础上,综合运用STAGE(scenario toolkit and generation environment)仿真软件,给出以HLA为核心的无人机作战仿真系统框架,构建无人机和导弹等关键实体扩展模型,开发了战场仿真环境。结合无人机典型作战想定,设计了仿真流程,并进行仿真推演。结果表明此战法打击效果较好,具有一定实用意义,为无人机作战研究提供了一种新的可行研究思路。展开更多
文摘The Menyuan Basin is a structural basin located inside the Qilianshan Mountains, the northern edge of Qinghai—Tibet Plateau, the surface of which is about 3000m ASL. To the south of this basin is the Dabanshan Mountain and to the north, the Lenglongling Mountain, which are 4000m ASL.. The neotectonic movement within this area is intense and can be divided into 6 stages.1 The basic data for identifying the stages of the neotectonic movement (1) Deformation of Tertiary deposit: Of the Tertiary system, only Baiyanghe Formation exists in the studied area, distributing at the boundary and under the bottom of the basin with Quaternary deposits discontinuously overlying it. Baiyanghe Formation has been intensely offset and folded, the folding dose not appear in Quaternary deposits. Its exact age remains unknown.(2) Deformation of Quaternary deposits: Most of Quaternary deposits belong to glacial and fluvial deposits, which have been offset and uplifted or sunk by neotectonic movement.(3) Deformation of the geomorphic surfaces: In the studied area exist many types and many orders of geomorphic surfaces, including 2 orders of planation surfaces, 3 orders of glacial platforms, 3 orders of river terraces and 2 orders of alluvial fans. Their ages are dated or comparatively estimated. All of them have been offset and uplifted or subsided by neotectonic movement. They are the time scales for dividing the stages of neotectonic movement.
文摘Ⅰ. INTRODUCTION How to teach listening comprehension in the classroom tends to get neglec-ted altegther. This is because an English teacher saw the need for givinghis students praetice but failed to take account of several important things,such as: (1)Texts should not be so difficult. As it is, they are almest alwaysabeve the level of the students. (2)Students should not be asked to remember everything they hear. (3)Students should be given guided practice to learn to take notes. (4)The teachor should relate their listening practice to the real-lifesituations in which the students would actually want to use the skill.
文摘Electric submersible pumps were widely used in agricultural fields,petroleum and various other industries. The pressure pulsation caused fatigue failure due to vibration in electric submersible pump and affects the life and performance of its system. The objective of this study was to experimentally investigate the characteristics of pressure pulsation which were generated at various stages of a multistage electric submersible pump during closed valve operation at different speeds. An electric submersible pump with five stages was selected for conducting experiments. A variable frequency drive( VFD)was used to operate the electric submersible pump at five different speed settings from 40 to 60 Hz. Piezoresistive pressure transducers were mounted at each stage of the electric submersible pump to capture the unsteady pressure signals. At each speed setting,the electric submersible pump was operated at the shut-off condition and the signals of unsteady pressure from all the five stages were captured. A fast fourier transformation( FFT) was carried out on the pressure signals to convert into frequency domain.From the spectra of pressure pulsation signals,the characteristics of pressure pulsation are obtained for each stage and for various speed settings which were then used to understand its variation with speed and stages.
基金financial support extended by the Cotton Mission Mode project TMC MM1 3. 3
文摘Blaptostethus pallescens Poppius (Heteroptera:Anthocoridae),which is amenable to mass rearing,has proved to be a potential predator of sucking pests like mites and thrips.Recently,the cotton mealybug Phenacoccus solenopsis Tinsley emerged as a serious pest on cotton in India.Laboratory studies indicated that B.pallescens could feed on the cotton mealybug.Hence,further investigations were conducted to understand the stage of the predator which is most potential and the pest stage preferred by the predator.Mature nymphs and adults of B.pallescens could predate equally well on the neonates of cotton mealybug.Young (three to four-day-old) nymphs of the predator could not feed on any stage of the cotton mealybug.Mature nymphs (seven-day-old and above) and adults could effectively predate on both young and mature cotton mealybug crawlers,though preference was more for the younger crawlers.However,nymphs and adults of B.pallescens could not predate on the adult stage of the mealybug.Different predator:pest ratios were tested in cage studies and it emerged that B.pallescens adults released against the mealybug crawlers at a ratio of 1:5 and nymphal release at 1:10 caused maximum mortality of the mealybug crawlers.Considering the fast multiplication rate of cotton mealybug and the large number of predators which have to be released to manage them,further detailed studies are necessary on utilizing B.pallescens to target the neonates and younger stages of the cotton mealybug in field conditions.
基金Supported by the Heilongjiang Provincial Natural Science Foundation of China(YQ2020C028)the Science and Technology Basic Resources Investigation Program of China(2019FY100503)+2 种基金the Science and Technology Development Project of Jilin Province(YDZJ202402007CXJD)the Key Special Project of the"Science and Technology Revitalization of Mongolia"Action(2022EEDSKJXM001)Shen-nong Talent Plan of the Ministry of Agriculture and Rural Affairs(SNYCQN138-2022)。
文摘Heracleum dissectum Ledeb.(HD)with high edible and medicinal values is distributed in Northeast Asia.To provide a reference for selecting appropriate parts and periods to harvest HD,the nutrient contents in different parts of HD at three growth stages were determined.The nutrients being determined are essential nutrients closely related to human needs,and the crude protein content of HD was 3.58‒28.43 g•100 g^(-1)DW(dry weight),sugar content was 2.33‒30.92 g•100 g^(-1)DW,and soluble dietary fiber content was 9.71‒26.09 g•100 g^(-1)DW.Crude protein was mainly distributed in leaf blades and inflorescences,sugar was primarily found in roots,and dietary fiber was predominantly located in leaves.From the leaf development stage to the flowering stage and then to the late seed harvest stage,the content of moisture,crude protein and soluble sugar first decreased and then increased.In contrast,the content of dietary fiber and crude fat first increased and then decreased.
基金Projects(52174096, 52304110) supported by the National Natural Science Foundation of China。
文摘Water is a critical factor affecting the mechanical properties of rocks, leading to their degradation. Understanding the creep mechanical behavior of deep roadway surrounding rock under the influence of underground water is of great significance. Compression and creep experiments on sandstone with varying water contents were conducted using a deep soft rock five-linked rheological experiment system. The experimental conditions, including water content (0%, 0.8%, 1.6%, 2.4% and 3.3%) and confining pressure (0, 6, 9 and 12 MPa), were determined based on pressure-free water absorption tests and in-situ stress measurements. The experimental results show that the compressive strength, creep failure stress, and dilatancy stress of sandstone decrease exponentially with increasing water content, while they increase exponentially with confining pressure. The ratio of lateral to axial instantaneous strain increases nearly linearly with the increase of stress, and the lateral creep strain characteristics of the sample are more significant than the axial ones. The duration of the attenuation creep stage of sandstone decreases with increasing water content and increases with increasing confining pressure. The lateral strain enters the steady-state creep stage before the axial strain, and the onset time of the accelerated creep stage of lateral strain under the failure stress is earlier than that of axial strain. The long-term strength of sandstone was determined based on the lateral steady-state creep rate curve, showing a negative exponential relationship with water content and a positive exponential relationship with confining pressure. A method for determining the long-term strength of rocks based on the ratio of lateral strain to axial strain (μc) is proposed, which is independent of water content. The research results provide a reliable theoretical basis for the analysis of the long-term stability of roadways under the influence of groundwater and the early prediction of creep failure.
文摘基于重复轨道航天飞机SIR-C的L和C波段极化干涉雷达数据,提出了一种将三阶段反演方法(Three-Stage Inversion)和ESPRIT(Estimation of Signal Parameters via Rotational Invariance Techniques)算法相结合的新的相位基植被高度估计方法.首先,基于L波段极化干涉数据,用三阶段反演方法获取植被覆盖地表下地形有效散射中心的相位;接着,基于C波段极化干涉数据,用ESPRIT算法估计植被冠层有效散射中心的相位;最后,对二者的相位差进行相位到高度的转换得到植被的高度.根据研究区域的实测林相数据,对该算法估计的植被高度结果进行了比较和验证,结果表明:该方法具有足够高的植被高度估计精度,如果能得到P和X波段的双频极化干涉雷达数据,该方法估计植被高度的精度将会得到进一步的提高.
文摘在对无人机作战特点及使用样式深入研究的基础上,综合运用STAGE(scenario toolkit and generation environment)仿真软件,给出以HLA为核心的无人机作战仿真系统框架,构建无人机和导弹等关键实体扩展模型,开发了战场仿真环境。结合无人机典型作战想定,设计了仿真流程,并进行仿真推演。结果表明此战法打击效果较好,具有一定实用意义,为无人机作战研究提供了一种新的可行研究思路。
