Projective synchronization problems of a drive system and a particular response network were investigated,where the drive system is an arbitrary system with n+1 dimensions;it may be a linear or nonlinear system,and ev...Projective synchronization problems of a drive system and a particular response network were investigated,where the drive system is an arbitrary system with n+1 dimensions;it may be a linear or nonlinear system,and even a chaotic or hyperchaotic system,the response network is complex system coupled by N nodes,and every node is showed by the approximately linear part of the drive system.Only controlling any one node of the response network by designed controller can achieve the projective synchronization.Some numerical examples were employed to verify the effectiveness and correctness of the designed controller.展开更多
The worm wheel whose undercutting characteristic is researched is a member of offsetting normal arc-toothed cylindrical worm drive.The tooth profile of the worm in its offsetting normal section is a circular arc.The n...The worm wheel whose undercutting characteristic is researched is a member of offsetting normal arc-toothed cylindrical worm drive.The tooth profile of the worm in its offsetting normal section is a circular arc.The normal vector used to calculate the first-type limit function is determined in the natural frame without the aid of the curvature parameter of worm helicoid.The first-type limit line is ascertained via solving the nonlinear equations iteratively.It is discovered that one first-type limit line exists on the tooth surface of worm wheel by numerical simulation,and such a line is normally located out of the meshing zone.Only one intersection point exists between the first and second-types of limit lines,and this point is a lubrication weak point.The undercutting mechanism is essentially that a part of the meshing zone near the conjugated line of worm tooth crest will come into the undercutting area and will be cut off during machining the worm wheel.The machining simulation verifies the correctness of undercutting mechanism.Moreover,a convenient and practical characteristic quantity is proposed to judge whether the undercutting exists in the whole meshing zone via computing the first-type limit function values on the worm tooth crest.展开更多
The impact safety of explosive charges has been focused in these decades. The fragment impact is widely used to evaluate the response of explosive charges. In our work, the explosive detonation driving technique was u...The impact safety of explosive charges has been focused in these decades. The fragment impact is widely used to evaluate the response of explosive charges. In our work, the explosive detonation driving technique was used to generate a high velocity fragment with large mass. When the fragment masses are10 g, 16 g, 25 g, and 50 g, the highest velocity of fragments can reach 2400 m/s, 2100 m/s, 1900 m/s, and1400 m/s, respectively. The high velocity fragment with large mass was used to evaluate the safety of two kinds of CL-20 based explosive charges. The effects of the fragment mass and velocity were analyzed.Especially, the reaction extent was obtained based on visible phenomenon. The CL-20-based explosive charge containing Al had a higher safety level than that without Al. It was because Al had good ductility,and further improved the mechanical property of the material. Also, the numerical simulation was conducted to understand the reaction characteristics of the CL-20-based explosive charge. The results showed that as the fragment mass and velocity increased, the reaction became more violent.展开更多
A three-DOF (degree of freedom) planar robot completely restrained and positioned parallel pulled by four wires was studied. The wire driving properties were analyzed through experiments. The restrained three-DOF plan...A three-DOF (degree of freedom) planar robot completely restrained and positioned parallel pulled by four wires was studied. The wire driving properties were analyzed through experiments. The restrained three-DOF planar platform was established based on slippery course and bearing, and dSPACE real-time control system was used to perform the platform's motion control experiment on robot. Based on the kinematic equation and mechanical balance equation of moving platform, the stiffness of the robot system was analyzed and the calibration scheme of the system considering wire tension was put forward. Position servo control experiments were carried out, position servo tracking precision was analyzed, and real-time wire tension was detected. The results show that the moving error of the moving platform tracking is small (the maximum difference is about 3%), and the rotation error is large (the maximum difference is about 12%). The wire tension has wave properties (the wire tension fluctuation is about 10 N).展开更多
For regional ecological management,it is important to evaluate the quality of ecosystems and analyze the underlying causes of ecological changes.Using the Google Earth Engine(GEE)platform,the remote sensing ecological...For regional ecological management,it is important to evaluate the quality of ecosystems and analyze the underlying causes of ecological changes.Using the Google Earth Engine(GEE)platform,the remote sensing ecological index(RSEI)was calculated for the Lijiang River Basin in Guangxi Zhuang Autonomous Region for 1991,2001,2011,and 2021.Spatial autocorrelation analysis was employed to investigate spatiotemporal variations in the ecological environmental quality of the Lijiang River Basin.Furthermore,geographic detectors were used to quantitatively analyze influencing factors and their interaction effects on ecological environmental quality.The results verified that:1)From 1991 to 2021,the ecological environmental quality of the Lijiang River Basin demonstrated significant improvement.The area with good and excellent ecological environmental quality in proportion increased by 19.69%(3406.57 km^(2)),while the area with fair and poor ecological environmental quality in proportion decreased by 10.76%(1860.36 km^(2)).2)Spatially,the ecological environmental quality of the Lijiang River Basin exhibited a pattern of low quality in the central region and high quality in the periphery.Specifically,poor ecological environmental quality characterized the Guilin urban area,Pingle County,and Lingchuan County.3)From 1991 to 2021,a significant positive spatial correlation was observed in ecological environmental quality of the Lijiang River Basin.Areas with high-high agglomeration were predominantly forests and grasslands,indicating good ecological environmental quality,whereas areas with low-low agglomeration were dominated by cultivated land and construction land,indicating poor ecological environmental quality.4)Annual average precipitation and temperature exerted the most significant influence on the ecological environmental quality of the basin,and their interactions with other factors had the great influence.This study aimed to enhance understanding of the evolution of the ecological environment in the Lijiang River Basin of Guangxi Zhuang Autonomous Region and provide scientific guidance for decision-making and management related to ecology in the region.展开更多
Taking CL-20(Hexanitrohexaazaisowurtzitane)-based aluminized explosives with high gurney energy as the research object, this research experimentally investigates the work capability of different aluminized explosive f...Taking CL-20(Hexanitrohexaazaisowurtzitane)-based aluminized explosives with high gurney energy as the research object, this research experimentally investigates the work capability of different aluminized explosive formulations when driving metal flyer plates in the denotation wave propagation direction.The research results showed that the formulations with 43 μm aluminum(Al) powder particles(The particle sizes of Al powder were in the range of 2~43 μm) exhibited the optimal performance in driving flyer plates along the denotation wave propagation direction. Compared to the formulations with Al powder 13 μm, the formulations with Al powder 2 μm delivered better performance in accelerating metal flyer plates in the early stage, which, however, turned to be poor in the later stage. The CL-20-based explosives containing 25% Al far under-performed those containing 15% Al. Based on the proposed quasi-isentropic hypothesis, relevant isentropy theories, and the functional relationship between detonation parameters and entropy as well as Al reaction degree, the characteristic lines of aluminized explosives in accelerating flyer plates were theoretically studied, a quasi-isentropic theoretical model for the aluminized explosive driving the flyer plate was built and the calculation methods for the variations of flyer plate velocity, Al reaction degree, and detonation product parameters with time and axial positions were developed. The theoretical model built is verified by the experimental results of the CL-20-based aluminized explosive driving flyer plate. It was found that the model built could accurately calculate the variations of flyer plate velocity and Al reaction degree over time. In addition, how physical parameters including detonation product pressure and temperature varied with time and axial positions was identified. The action time of the positive pressure after the detonation of aluminized explosives was found prolonged and the downtrend of the temperature was slowed down and even reversed to a slight rise due to the aftereffect reaction between the Al powder and the detonation products.展开更多
为明晰水肥耦合对炭基质栽培番茄产量品质的提升效应,将生物炭混掺到由酒糟、秸秆等农业废弃物拌制成的基质模块中,设置2个灌溉量(I_(1):100%ET_(c),I_(2):80%ET_(c),ET_(c)为作物蒸发蒸腾量),2个施肥量(N-P_(2)O_(5)-K_(2)O)(F_(1):240...为明晰水肥耦合对炭基质栽培番茄产量品质的提升效应,将生物炭混掺到由酒糟、秸秆等农业废弃物拌制成的基质模块中,设置2个灌溉量(I_(1):100%ET_(c),I_(2):80%ET_(c),ET_(c)为作物蒸发蒸腾量),2个施肥量(N-P_(2)O_(5)-K_(2)O)(F_(1):240-180-200 kg/hm^(2),F2:180-135-150 kg/hm^(2))及基质中4个生物炭添加量(B0:0,B1:1%,B3:3%,B5:5%),共16组处理,研究水肥耦合对炭基质栽培番茄叶面积指数(leaf area index,LAI)、叶绿素相对含量(soil and plant analyzer development,SPAD)、植株养分(全氮、全钾、有机碳)吸收量、化学计量特征(氮钾比、碳氮比)、产量及品质(可溶性固形物含量、维生素C含量、硝酸盐含量、可溶性糖含量、可滴定酸含量、糖酸比)的影响,揭示炭基质栽培番茄产量及品质的关键驱动因子,构建以番茄产量、品质及其关键驱动因子为目标的熵权-TOPSIS多目标综合评价模型,提出水肥与炭基质耦合的最优方案。结果表明:炭基质对番茄LAI、SPAD值、养分吸收量、产量及品质影响显著(P<0.05);在相同灌溉和施肥条件下,炭基质增加了番茄整株钾吸收量、整株碳同化量、产量及维生素C含量,降低了硝酸盐含量;基于结构方程模型,番茄整株碳同化量是产量的关键驱动因子,其增加有助于提高番茄产量,氮钾比是品质的关键驱动因子,其降低有助于改善番茄品质;采用熵权-TOPSIS多目标综合评价模型,筛选出I_(1)F_(2)B_(3)处理是水肥与炭基质耦合的最优方案。研究可为农业废弃物高效利用及高品质果蔬的水肥炭有效管理提供理论依据。展开更多
基金Supported by the National Natural Science Foundation of China (11161027)。
文摘Projective synchronization problems of a drive system and a particular response network were investigated,where the drive system is an arbitrary system with n+1 dimensions;it may be a linear or nonlinear system,and even a chaotic or hyperchaotic system,the response network is complex system coupled by N nodes,and every node is showed by the approximately linear part of the drive system.Only controlling any one node of the response network by designed controller can achieve the projective synchronization.Some numerical examples were employed to verify the effectiveness and correctness of the designed controller.
基金Projects(52205069,52075083,52304049)supported by the National Natural Science Foundation of ChinaProject(2021-BS-164)supported by the Liaoning Province Doctoral Research Startup Fund,China+2 种基金Project(LJKZ0264)supported by the Science and Technology Research Projects of Education Department of Liaoning Province,ChinaProject(G2022003010L)supported by the High-end Foreign Experts Recruitment Plan of ChinaProject(E2021203095)supported by the Natural Science Foundation for Young Scholars of Hebei Province,China。
文摘The worm wheel whose undercutting characteristic is researched is a member of offsetting normal arc-toothed cylindrical worm drive.The tooth profile of the worm in its offsetting normal section is a circular arc.The normal vector used to calculate the first-type limit function is determined in the natural frame without the aid of the curvature parameter of worm helicoid.The first-type limit line is ascertained via solving the nonlinear equations iteratively.It is discovered that one first-type limit line exists on the tooth surface of worm wheel by numerical simulation,and such a line is normally located out of the meshing zone.Only one intersection point exists between the first and second-types of limit lines,and this point is a lubrication weak point.The undercutting mechanism is essentially that a part of the meshing zone near the conjugated line of worm tooth crest will come into the undercutting area and will be cut off during machining the worm wheel.The machining simulation verifies the correctness of undercutting mechanism.Moreover,a convenient and practical characteristic quantity is proposed to judge whether the undercutting exists in the whole meshing zone via computing the first-type limit function values on the worm tooth crest.
文摘The impact safety of explosive charges has been focused in these decades. The fragment impact is widely used to evaluate the response of explosive charges. In our work, the explosive detonation driving technique was used to generate a high velocity fragment with large mass. When the fragment masses are10 g, 16 g, 25 g, and 50 g, the highest velocity of fragments can reach 2400 m/s, 2100 m/s, 1900 m/s, and1400 m/s, respectively. The high velocity fragment with large mass was used to evaluate the safety of two kinds of CL-20 based explosive charges. The effects of the fragment mass and velocity were analyzed.Especially, the reaction extent was obtained based on visible phenomenon. The CL-20-based explosive charge containing Al had a higher safety level than that without Al. It was because Al had good ductility,and further improved the mechanical property of the material. Also, the numerical simulation was conducted to understand the reaction characteristics of the CL-20-based explosive charge. The results showed that as the fragment mass and velocity increased, the reaction became more violent.
基金Project(20102304120007) supported by the Research Fund for the Doctoral Program of Higher Education of ChinaProject(QC2010009)supported by the Natural Science Foundation of Heilongjiang Province, China+1 种基金Projects(20110491030, LBH-Z10219) supported by China Postdoctoral Science FoundationProject(HEUCF120706) supported by the Fundamental Research Funds for the Central Universities of China
文摘A three-DOF (degree of freedom) planar robot completely restrained and positioned parallel pulled by four wires was studied. The wire driving properties were analyzed through experiments. The restrained three-DOF planar platform was established based on slippery course and bearing, and dSPACE real-time control system was used to perform the platform's motion control experiment on robot. Based on the kinematic equation and mechanical balance equation of moving platform, the stiffness of the robot system was analyzed and the calibration scheme of the system considering wire tension was put forward. Position servo control experiments were carried out, position servo tracking precision was analyzed, and real-time wire tension was detected. The results show that the moving error of the moving platform tracking is small (the maximum difference is about 3%), and the rotation error is large (the maximum difference is about 12%). The wire tension has wave properties (the wire tension fluctuation is about 10 N).
基金supported by the Guangxi Natural Science Foundation(2020GXNSFAA297266)Doctoral Research Foundation of Guilin University of Technology(GUTQDJJ2007059)Guangxi Hidden Metallic Mineral Exploration Key Laboratory。
文摘For regional ecological management,it is important to evaluate the quality of ecosystems and analyze the underlying causes of ecological changes.Using the Google Earth Engine(GEE)platform,the remote sensing ecological index(RSEI)was calculated for the Lijiang River Basin in Guangxi Zhuang Autonomous Region for 1991,2001,2011,and 2021.Spatial autocorrelation analysis was employed to investigate spatiotemporal variations in the ecological environmental quality of the Lijiang River Basin.Furthermore,geographic detectors were used to quantitatively analyze influencing factors and their interaction effects on ecological environmental quality.The results verified that:1)From 1991 to 2021,the ecological environmental quality of the Lijiang River Basin demonstrated significant improvement.The area with good and excellent ecological environmental quality in proportion increased by 19.69%(3406.57 km^(2)),while the area with fair and poor ecological environmental quality in proportion decreased by 10.76%(1860.36 km^(2)).2)Spatially,the ecological environmental quality of the Lijiang River Basin exhibited a pattern of low quality in the central region and high quality in the periphery.Specifically,poor ecological environmental quality characterized the Guilin urban area,Pingle County,and Lingchuan County.3)From 1991 to 2021,a significant positive spatial correlation was observed in ecological environmental quality of the Lijiang River Basin.Areas with high-high agglomeration were predominantly forests and grasslands,indicating good ecological environmental quality,whereas areas with low-low agglomeration were dominated by cultivated land and construction land,indicating poor ecological environmental quality.4)Annual average precipitation and temperature exerted the most significant influence on the ecological environmental quality of the basin,and their interactions with other factors had the great influence.This study aimed to enhance understanding of the evolution of the ecological environment in the Lijiang River Basin of Guangxi Zhuang Autonomous Region and provide scientific guidance for decision-making and management related to ecology in the region.
基金National Natural Science Foundation of China(Grant No.11872120).
文摘Taking CL-20(Hexanitrohexaazaisowurtzitane)-based aluminized explosives with high gurney energy as the research object, this research experimentally investigates the work capability of different aluminized explosive formulations when driving metal flyer plates in the denotation wave propagation direction.The research results showed that the formulations with 43 μm aluminum(Al) powder particles(The particle sizes of Al powder were in the range of 2~43 μm) exhibited the optimal performance in driving flyer plates along the denotation wave propagation direction. Compared to the formulations with Al powder 13 μm, the formulations with Al powder 2 μm delivered better performance in accelerating metal flyer plates in the early stage, which, however, turned to be poor in the later stage. The CL-20-based explosives containing 25% Al far under-performed those containing 15% Al. Based on the proposed quasi-isentropic hypothesis, relevant isentropy theories, and the functional relationship between detonation parameters and entropy as well as Al reaction degree, the characteristic lines of aluminized explosives in accelerating flyer plates were theoretically studied, a quasi-isentropic theoretical model for the aluminized explosive driving the flyer plate was built and the calculation methods for the variations of flyer plate velocity, Al reaction degree, and detonation product parameters with time and axial positions were developed. The theoretical model built is verified by the experimental results of the CL-20-based aluminized explosive driving flyer plate. It was found that the model built could accurately calculate the variations of flyer plate velocity and Al reaction degree over time. In addition, how physical parameters including detonation product pressure and temperature varied with time and axial positions was identified. The action time of the positive pressure after the detonation of aluminized explosives was found prolonged and the downtrend of the temperature was slowed down and even reversed to a slight rise due to the aftereffect reaction between the Al powder and the detonation products.
文摘为明晰水肥耦合对炭基质栽培番茄产量品质的提升效应,将生物炭混掺到由酒糟、秸秆等农业废弃物拌制成的基质模块中,设置2个灌溉量(I_(1):100%ET_(c),I_(2):80%ET_(c),ET_(c)为作物蒸发蒸腾量),2个施肥量(N-P_(2)O_(5)-K_(2)O)(F_(1):240-180-200 kg/hm^(2),F2:180-135-150 kg/hm^(2))及基质中4个生物炭添加量(B0:0,B1:1%,B3:3%,B5:5%),共16组处理,研究水肥耦合对炭基质栽培番茄叶面积指数(leaf area index,LAI)、叶绿素相对含量(soil and plant analyzer development,SPAD)、植株养分(全氮、全钾、有机碳)吸收量、化学计量特征(氮钾比、碳氮比)、产量及品质(可溶性固形物含量、维生素C含量、硝酸盐含量、可溶性糖含量、可滴定酸含量、糖酸比)的影响,揭示炭基质栽培番茄产量及品质的关键驱动因子,构建以番茄产量、品质及其关键驱动因子为目标的熵权-TOPSIS多目标综合评价模型,提出水肥与炭基质耦合的最优方案。结果表明:炭基质对番茄LAI、SPAD值、养分吸收量、产量及品质影响显著(P<0.05);在相同灌溉和施肥条件下,炭基质增加了番茄整株钾吸收量、整株碳同化量、产量及维生素C含量,降低了硝酸盐含量;基于结构方程模型,番茄整株碳同化量是产量的关键驱动因子,其增加有助于提高番茄产量,氮钾比是品质的关键驱动因子,其降低有助于改善番茄品质;采用熵权-TOPSIS多目标综合评价模型,筛选出I_(1)F_(2)B_(3)处理是水肥与炭基质耦合的最优方案。研究可为农业废弃物高效利用及高品质果蔬的水肥炭有效管理提供理论依据。
