The fission fragment mass-yields are evaluated for pre-actinide and actinide isotopes using a systematic statistical scission point model.The total potential energy of the fissioning systems at the scission point is p...The fission fragment mass-yields are evaluated for pre-actinide and actinide isotopes using a systematic statistical scission point model.The total potential energy of the fissioning systems at the scission point is presented in approximate relations as functions of mass numbers,deformation parameters and the temperature of complementary fission fragments.The collective temperature,Tcoll,and the temperature of fission fragments,Ti,are separated and the effect of collective temperature on mass yields results is investigated.The fragment temperature has been calculated with the generalized superfluid model.The sum of deformation parameters of complementary fission fragments has been obtained by fitting the calculated results with the experimental data.To investigate the transitions between symmetric and asymmetric modes mass yields for pre-actinide and heavy actinides are calculated with this model.The transition from asymmetric to symmetric fission is well reproduced using this systematic statistical scission point model.The calculated results are in good agreement with the experimental data with Tcoll=2 Me V at intermediate excitation energy and with T_(coll)=1MeV for spontaneous fission.Despite the Langevin model,in the scission point model,a constraint on the deformation parameters of fission fragments has little effect on the results of the mass yield.展开更多
The fragment angular distributions of fusion-fission reactions for the systemsof <sup>16</sup>O+<sup>232</sup>Th,<sup>19</sup>F+<sup>232</sup>Th and <sup>16</su...The fragment angular distributions of fusion-fission reactions for the systemsof <sup>16</sup>O+<sup>232</sup>Th,<sup>19</sup>F+<sup>232</sup>Th and <sup>16</sup>O+<sup>238</sup>U at near-and sub-barrier energies were measured.The measured fragment anisotropies obviously deviate from the predictions ofscission-point transition-state model.We also compared the excitation energy of tiltingmode with the statistical assumption.It was found that thermal equilibrium is not estab-lished at scission for the reactions studied.展开更多
A new calibration model of a radio telescope that includes pointing error is presented, which considers nonlinear errors in the azimuth axis. For a large radio telescope, in particular for a telescope with a turntable...A new calibration model of a radio telescope that includes pointing error is presented, which considers nonlinear errors in the azimuth axis. For a large radio telescope, in particular for a telescope with a turntable, it is difficult to correct pointing errors using a traditional linear calibration model, because errors produced by the wheel-on-rail or center bearing structures are generally nonlinear. Fourier expansion is made for the oblique error and parameters describing the inclination direction along the azimuth axis based on the linear calibration model, and a new calibration model for pointing is derived. The new pointing model is applied to the 40 m radio telescope administered by Yunnan Observatories, which is a telescope that uses a turntable. The results show that this model can significantly reduce the residual systematic errors due to nonlinearity in the azimuth axis compared with the linear model.展开更多
Divertor plasma detachment offers one of the most promising operating modes for fusion devices because of low target power loading. In this article a ＇two-point＇ model is used to investigate the formation of detachm...Divertor plasma detachment offers one of the most promising operating modes for fusion devices because of low target power loading. In this article a ＇two-point＇ model is used to investigate the formation of detachment and explore the route to detachment in EAST, in order to find an ideal operation window. The simulation results show that impurity radiation and ionneutral friction are the main causes of divertor plasma detachment at the target plates. Raising the safety factor and reducing the upstream power density provide effective means to achieve the detachment due to the increased radiation power fraction. Puffing Ar and Ne impurities and raising the safety factor can bring the upstream high plasma temperature region （above 100 eV） and the low target plasma temperature region （below 10 eV） close to each other in terms of the separatrix density. But it is difficult to find a common operating region which satisfies both conditions. High recycling and detached regimes provides an ideal operation window because of the steady upstream condition and low target power load.展开更多
A two-phase trend model is presented to investigate the turning-point signals of evolution trend in long-term series of a climatic element. Based on nonlinear fitting, the revised model brings out more evident improve...A two-phase trend model is presented to investigate the turning-point signals of evolution trend in long-term series of a climatic element. Based on nonlinear fitting, the revised model brings out more evident improvement of the linear model proposed by Solow et al. (1987). Both theoretical deduction and case calculation show that our version can search the turning point and period accurately and objectively. In particular it is fit for computer exploring the turning points in long-range records from stations covering a large area, thus avoiding subjective judgement by a usual drawing method.展开更多
Generation of mouse models carrying a defined point mutation,especially disease-related point mutations,is of considerable interest for research in biology and medicine.The standard method based on embryonic stem cell...Generation of mouse models carrying a defined point mutation,especially disease-related point mutations,is of considerable interest for research in biology and medicine.The standard method based on embryonic stem cell（ESC）-mediated homologous recombination（HR）is time-and labor-consuming.展开更多
Aiming at the deficiency of the robustness of thermal error compensation models of CNC machine tools, the mechanism of improving the models＇ robustness is studied by regarding the Leaderway-V450 machining center as t...Aiming at the deficiency of the robustness of thermal error compensation models of CNC machine tools, the mechanism of improving the models＇ robustness is studied by regarding the Leaderway-V450 machining center as the object. Through the analysis of actual spindle air cutting experimental data on Leaderway-V450 machine, it is found that the temperature-sensitive points used for modeling is volatility, and this volatility directly leads to large changes on the collinear degree among modeling independent variables. Thus, the forecasting accuracy of multivariate regression model is severely affected, and the forecasting robustness becomes poor too. To overcome this effect, a modeling method of establishing thermal error models by using single temperature variable under the jamming of temperature-sensitive points＇ volatility is put forward. According to the actual data of thermal error measured in different seasons, it is proved that the single temperature variable model can reduce the loss of fore- casting accuracy resulted from the volatility of tempera- ture-sensitive points, especially for the prediction of cross quarter data, the improvement of forecasting accuracy is about 5 μm or more. The purpose that improving the robustness of the thermal error models is realized, which can provide a reference for selecting the modelingindependent variable in the application of thermal error compensation of CNC machine tools.展开更多
[Objective] The aim was to study the control model of rural non-point source pollution.[Method] Taking Ninghe County(a typical agricultural county in Tianjin) as an example,the current development of local economy and...[Objective] The aim was to study the control model of rural non-point source pollution.[Method] Taking Ninghe County(a typical agricultural county in Tianjin) as an example,the current development of local economy and society and characteristics of rural non-point source pollution were studied firstly,then the control model of rural non-point source pollution suitable for Ninghe County was constructed,and its environmental and economic benefits were analyzed finally.[Result] According to the sources of non-point source pollution,the control model of rural non-point source pollution in Ninghe County was divided into three modules from the aspects of planting industry,livestock raising industry and rural living.The main content of non-point source pollution control module of planting industry was composed of rational utilization of chemicals,water-saving irrigation,diversified utilization of straw etc.Non-point source pollution control module of livestock raising industry focused on the site selection of farm or raising zones,choice of raising mode,comprehensive utilization of livestock waste etc.In the non-point source pollution control module of rural living,villages were divided into two types(small town and ecological village) based on various geographical positions.In a word,these three modules were interrelated and targeted for non-point source pollution control in villages under different development situations.[Conclusion] The study could provide references for the rural non-point source pollution control in Hai River basin and other regions of Northern China.展开更多
BACKGROUND：It has been shown that interleukin-1 （IL-1） may cause inflammatory reactions, which stimulate the nerve root of patients with lumbar intervertebral disc protrusion and leads to pain. Whether the clinical...BACKGROUND：It has been shown that interleukin-1 （IL-1） may cause inflammatory reactions, which stimulate the nerve root of patients with lumbar intervertebral disc protrusion and leads to pain. Whether the clinical curative effects of acupuncture in the treatment of lumbar and leg pain are linked to an inhibition of local IL-1 secretion is unknown. OBJECTIVE： To assess the influence of acupuncture on IL-1, this study was designed to verify the effects of acupuncture at the ＂Huatuojiaji （Extra）＂ point on the nerve root in a rat model of lumbar nerve root compression, compared with administration of meloxicam, a non-steroidal anti-inflammatory drug. DESIGN, TIME AND SETTING： Randomized, controlled, molecular biology experiment, performed at the Experimental Center, Sixth People’s Hospital Affiliated to Shanghai Jiao Tong University between September 2005 and April 2006. MATERIALS： Forty healthy adult Sprague Dawley rats of either gender were included in this study. The rats were randomly and evenly divided into the following four groups： normal control, model, acupuncture and meloxicam groups. Lumbar nerve root compression was induced in rats in the model, acupuncture, and meloxicam groups by inserting a specially made silicon rubber slice at the juncture of the L5 nerve root and the dural sac. The acupuncture needle （pattern number N3030, 30#, 1.5 inch） was purchased from Suzhou Medical Appliance Factory, China. IL-1 enzyme linked immunosorbent assay （ELISA） kit was purchased from Santa Cruz Biotechnology, Inc., USA. METHODS： The acupuncture group was acupunctured at the ＂Huatuojiaji＂ point, which is lateral to the compressed L5-6 nerve root, with an acupuncture depth of 0.5 cm. There were two treatment courses, each of involved seven 20-minute acupuncture sessions, one session a day. The meloxicam group was administered intragastrically 3.75 mg/kg meloxicam （5 mg meloxicam /10 mL physiological saline）. Rats in the normal control group and model group received an intragastric administration of 10 mL/kg physiological saline. All administrations were performed once a day. MAIN OUTCOME MEASURES： At day 14 post-surgery, the IL-1 level in the compressed nerve root was determined by a streptavidin-peroxidase （S-P） immunohistochemical method, and IL-1β mRNA expression in the compressed nerve root was simultaneously detected by real-time reverse transcription-polymerase chain reaction. RESULTS： The expression levels of IL-1 and IL-1β mRNA in the L5 nerve root were significantly higher in the model group than in the control group （P 〈 0.01）. However, the expression levels of IL-1 and IL-1β mRNA were significantly lower in the acupuncture and meloxicam groups than in the model group （P 〈 0.05–0.01）. Expression levels of IL-1 and IL-1β mRNA were significantly higher in the acupuncture group than in the meloxicam group （P 〈 0.01）. CONCLUSION： Acupuncture at the ＂Huatuojiaji＂ point decreases the IL-1 level by inhibiting IL-1β mRNA expression to a greater extent than meloxicam administration.展开更多
A number of statistical tests are proposed for the purpose of change-point detection in a general nonparametric regression model under mild conditions. New proofs are given to prove the weak convergence of the underly...A number of statistical tests are proposed for the purpose of change-point detection in a general nonparametric regression model under mild conditions. New proofs are given to prove the weak convergence of the underlying processes which assume remove the stringent condition of bounded total variation of the regression function and need only second moments. Since many quantities, such as the regression function, the distribution of the covariates and the distribution of the errors, are unspecified, the results are not distribution-free. A weighted bootstrap approach is proposed to approximate the limiting distributions. Results of a simulation study for this paper show good performance for moderate samples sizes.展开更多
Joint clearances in antenna pointing mechanisms lead to uncertainty in function deviation. Current studies mainly focus on radial clearance of revolute joints, while axial clearance has rarely been taken into consider...Joint clearances in antenna pointing mechanisms lead to uncertainty in function deviation. Current studies mainly focus on radial clearance of revolute joints, while axial clearance has rarely been taken into consideration. In fact, own?ing to errors from machining and assembly, thermal deformation and so forth, practically, axial clearance is inevitable in the joint. In this study, an error equivalent model(EEM) of revolute joints is proposed with considering both radial and axial clearances. Compared to the planar model of revolute joints only considering radial clearance, the journal motion inside the bearing is more abundant and matches the reality better in the EEM. The model is also extended for analyzing the error distribution of a spatial dual?axis("X–Y" type) antenna pointing mechanism of Spot?beam antennas which especially demand a high pointing accuracy. Three case studies are performed which illustrates the internal relation between radial clearance and axial clearance. It is found that when the axial clearance is big enough, the physical journal can freely realize both translational motion and rotational motion. While if the axial clearance is limited, the motion of the physical journal will be restricted. Analysis results indicate that the consideration of both radial and axial clearances in the revolute joint describes the journal motion inside the bearing more precise. To further validate the proposed model, a model of the EEM is designed and fabricated. Some suggestions on the design of revolute joints are also provided.展开更多
The internal turbulent flow in conical diffuser is a very complicated adverse pressure gradient flow.DLR k-ε turbulence model was adopted to study it.The every terms of the Laplace operator in DLR k-ε turbulence mod...The internal turbulent flow in conical diffuser is a very complicated adverse pressure gradient flow.DLR k-ε turbulence model was adopted to study it.The every terms of the Laplace operator in DLR k-ε turbulence model and pressure Poisson equation were discretized by upwind difference scheme.A new full implicit difference scheme of 5-point was constructed by using finite volume method and finite difference method.A large sparse matrix with five diagonals was formed and was stored by three arrays of one dimension in a compressed mode.General iterative methods do not work wel1 with large sparse matrix.With algebraic multigrid method(AMG),linear algebraic system of equations was solved and the precision was set at 10-6.The computation results were compared with the experimental results.The results show that the computation results have a good agreement with the experiment data.The precision of computational results and numerical simulation efficiency are greatly improved.展开更多
Non-line-of-sight(NLOS)imaging has emerged as a prominent technique for reconstructing obscured objects from images that undergo multiple diffuse reflections.This imaging method has garnered significant attention in d...Non-line-of-sight(NLOS)imaging has emerged as a prominent technique for reconstructing obscured objects from images that undergo multiple diffuse reflections.This imaging method has garnered significant attention in diverse domains,including remote sensing,rescue operations,and intelligent driving,due to its wide-ranging potential applications.Nevertheless,accurately modeling the incident light direction,which carries energy and is captured by the detector amidst random diffuse reflection directions,poses a considerable challenge.This challenge hinders the acquisition of precise forward and inverse physical models for NLOS imaging,which are crucial for achieving high-quality reconstructions.In this study,we propose a point spread function(PSF)model for the NLOS imaging system utilizing ray tracing with random angles.Furthermore,we introduce a reconstruction method,termed the physics-constrained inverse network(PCIN),which establishes an accurate PSF model and inverse physical model by leveraging the interplay between PSF constraints and the optimization of a convolutional neural network.The PCIN approach initializes the parameters randomly,guided by the constraints of the forward PSF model,thereby obviating the need for extensive training data sets,as required by traditional deep-learning methods.Through alternating iteration and gradient descent algorithms,we iteratively optimize the diffuse reflection angles in the PSF model and the neural network parameters.The results demonstrate that PCIN achieves efficient data utilization by not necessitating a large number of actual ground data groups.Moreover,the experimental findings confirm that the proposed method effectively restores the hidden object features with high accuracy.展开更多
The effect of rotation on the shape (figure) and gravitational quadrupole of astronomical bodies is calculated by using an approximate point core model: A point mass at the center of an ellipsoidal homogeneous fluid. ...The effect of rotation on the shape (figure) and gravitational quadrupole of astronomical bodies is calculated by using an approximate point core model: A point mass at the center of an ellipsoidal homogeneous fluid. Maclaurin’s analytical result for homogenous bodies generalizes to this model and leads to very accurate analytical results connecting the three observables: oblateness (ò), gravitational quadrupole (J2), and angular velocity parameter (q). The analytical results are compared to observational data for the planets and a good agreement is found. Oscillations near equilibrium are studied within the model.展开更多
[Objective]The study aimed to simulate the production and transportation process of surface runoff,sediment and non-point source pollution in Xincai River basin based on SWAT model.[Method]On the basis of analyzing th...[Objective]The study aimed to simulate the production and transportation process of surface runoff,sediment and non-point source pollution in Xincai River basin based on SWAT model.[Method]On the basis of analyzing the principles of SWAT model,the correlative parameters of runoff,sediment and water quality were calibrated,then the spatial and temporal distribution of runoff,sediment and non-point source pollutants in Xincai River basin were studied by using SWAT model.[Result]The results of calibration and validation showed that SWAT model was reasonable and available,and it can be used to simulate the non-point source pollution of Xincai River basin.The simulation results revealed that the load of sediment and various pollutants was the highest in the rainy year,followed by the normal year,while it was the minimum in the dry year,indicating that the production of sediment and non-point source pollutants was closely related to annual runoff.[Conclusion]The research could provide scientific references for the prevention of non-point source pollution in a basin.展开更多
Reduced order models(ROMs) based on the snapshots on the CFD high-fidelity simulations have been paid great attention recently due to their capability of capturing the features of the complex geometries and flow confi...Reduced order models(ROMs) based on the snapshots on the CFD high-fidelity simulations have been paid great attention recently due to their capability of capturing the features of the complex geometries and flow configurations. To improve the efficiency and precision of the ROMs, it is indispensable to add extra sampling points to the initial snapshots, since the number of sampling points to achieve an adequately accurate ROM is generally unknown in prior, but a large number of initial sampling points reduces the parsimony of the ROMs. A fuzzy-clustering-based adding-point strategy is proposed and the fuzzy clustering acts an indicator of the region in which the precision of ROMs is relatively low. The proposed method is applied to construct the ROMs for the benchmark mathematical examples and a numerical example of hypersonic aerothermodynamics prediction for a typical control surface. The proposed method can achieve a 34.5% improvement on the efficiency than the estimated mean squared error prediction algorithm and shows same-level prediction accuracy.展开更多
文摘The fission fragment mass-yields are evaluated for pre-actinide and actinide isotopes using a systematic statistical scission point model.The total potential energy of the fissioning systems at the scission point is presented in approximate relations as functions of mass numbers,deformation parameters and the temperature of complementary fission fragments.The collective temperature,Tcoll,and the temperature of fission fragments,Ti,are separated and the effect of collective temperature on mass yields results is investigated.The fragment temperature has been calculated with the generalized superfluid model.The sum of deformation parameters of complementary fission fragments has been obtained by fitting the calculated results with the experimental data.To investigate the transitions between symmetric and asymmetric modes mass yields for pre-actinide and heavy actinides are calculated with this model.The transition from asymmetric to symmetric fission is well reproduced using this systematic statistical scission point model.The calculated results are in good agreement with the experimental data with Tcoll=2 Me V at intermediate excitation energy and with T_(coll)=1MeV for spontaneous fission.Despite the Langevin model,in the scission point model,a constraint on the deformation parameters of fission fragments has little effect on the results of the mass yield.
基金The project supported by the National Natural Science Foundation of China under the contract No.19275067.
文摘The fragment angular distributions of fusion-fission reactions for the systemsof <sup>16</sup>O+<sup>232</sup>Th,<sup>19</sup>F+<sup>232</sup>Th and <sup>16</sup>O+<sup>238</sup>U at near-and sub-barrier energies were measured.The measured fragment anisotropies obviously deviate from the predictions ofscission-point transition-state model.We also compared the excitation energy of tiltingmode with the statistical assumption.It was found that thermal equilibrium is not estab-lished at scission for the reactions studied.
基金Supported by the National Natural Science Foundation of China
文摘A new calibration model of a radio telescope that includes pointing error is presented, which considers nonlinear errors in the azimuth axis. For a large radio telescope, in particular for a telescope with a turntable, it is difficult to correct pointing errors using a traditional linear calibration model, because errors produced by the wheel-on-rail or center bearing structures are generally nonlinear. Fourier expansion is made for the oblique error and parameters describing the inclination direction along the azimuth axis based on the linear calibration model, and a new calibration model for pointing is derived. The new pointing model is applied to the 40 m radio telescope administered by Yunnan Observatories, which is a telescope that uses a turntable. The results show that this model can significantly reduce the residual systematic errors due to nonlinearity in the azimuth axis compared with the linear model.
基金supported by National Natural Science Foundation of China(No.10675129)
文摘Divertor plasma detachment offers one of the most promising operating modes for fusion devices because of low target power loading. In this article a ＇two-point＇ model is used to investigate the formation of detachment and explore the route to detachment in EAST, in order to find an ideal operation window. The simulation results show that impurity radiation and ionneutral friction are the main causes of divertor plasma detachment at the target plates. Raising the safety factor and reducing the upstream power density provide effective means to achieve the detachment due to the increased radiation power fraction. Puffing Ar and Ne impurities and raising the safety factor can bring the upstream high plasma temperature region （above 100 eV） and the low target plasma temperature region （below 10 eV） close to each other in terms of the separatrix density. But it is difficult to find a common operating region which satisfies both conditions. High recycling and detached regimes provides an ideal operation window because of the steady upstream condition and low target power load.
基金This wirk is supported jointly National Natural Science Foundation of China and China Meteoroloical Administration 8th-Five-year Major Project Foundation.
文摘A two-phase trend model is presented to investigate the turning-point signals of evolution trend in long-term series of a climatic element. Based on nonlinear fitting, the revised model brings out more evident improvement of the linear model proposed by Solow et al. (1987). Both theoretical deduction and case calculation show that our version can search the turning point and period accurately and objectively. In particular it is fit for computer exploring the turning points in long-range records from stations covering a large area, thus avoiding subjective judgement by a usual drawing method.
基金supported by the Ministry of Science and Technology of China (2014CB964803 and 2015AA020307)the National Natural Science Foundation of China (Nos. 31530048, 31601163 and 81672117)+1 种基金he Chinese Academy of Sciences (XDB19010204 and QYZDJ-SSW-SMC023)the Shanghai Municipal Commission for Science and Technology(16JC1420500, 17JC1400900 and 17140901500)
文摘Generation of mouse models carrying a defined point mutation,especially disease-related point mutations,is of considerable interest for research in biology and medicine.The standard method based on embryonic stem cell（ESC）-mediated homologous recombination（HR）is time-and labor-consuming.
基金Supported by Key Project of National Natural Science Fund of China(Grant No.51490660/51490661)National Natural Science Foundation of China(Grant No.51175142)
文摘Aiming at the deficiency of the robustness of thermal error compensation models of CNC machine tools, the mechanism of improving the models＇ robustness is studied by regarding the Leaderway-V450 machining center as the object. Through the analysis of actual spindle air cutting experimental data on Leaderway-V450 machine, it is found that the temperature-sensitive points used for modeling is volatility, and this volatility directly leads to large changes on the collinear degree among modeling independent variables. Thus, the forecasting accuracy of multivariate regression model is severely affected, and the forecasting robustness becomes poor too. To overcome this effect, a modeling method of establishing thermal error models by using single temperature variable under the jamming of temperature-sensitive points＇ volatility is put forward. According to the actual data of thermal error measured in different seasons, it is proved that the single temperature variable model can reduce the loss of fore- casting accuracy resulted from the volatility of tempera- ture-sensitive points, especially for the prediction of cross quarter data, the improvement of forecasting accuracy is about 5 μm or more. The purpose that improving the robustness of the thermal error models is realized, which can provide a reference for selecting the modelingindependent variable in the application of thermal error compensation of CNC machine tools.
基金Supported by Hai River Basin Integrated Water Resources Management Project of Global Environment Facility(SEPA-ZWN-3,C/II/S/09/090)
文摘[Objective] The aim was to study the control model of rural non-point source pollution.[Method] Taking Ninghe County(a typical agricultural county in Tianjin) as an example,the current development of local economy and society and characteristics of rural non-point source pollution were studied firstly,then the control model of rural non-point source pollution suitable for Ninghe County was constructed,and its environmental and economic benefits were analyzed finally.[Result] According to the sources of non-point source pollution,the control model of rural non-point source pollution in Ninghe County was divided into three modules from the aspects of planting industry,livestock raising industry and rural living.The main content of non-point source pollution control module of planting industry was composed of rational utilization of chemicals,water-saving irrigation,diversified utilization of straw etc.Non-point source pollution control module of livestock raising industry focused on the site selection of farm or raising zones,choice of raising mode,comprehensive utilization of livestock waste etc.In the non-point source pollution control module of rural living,villages were divided into two types(small town and ecological village) based on various geographical positions.In a word,these three modules were interrelated and targeted for non-point source pollution control in villages under different development situations.[Conclusion] The study could provide references for the rural non-point source pollution control in Hai River basin and other regions of Northern China.
文摘BACKGROUND：It has been shown that interleukin-1 （IL-1） may cause inflammatory reactions, which stimulate the nerve root of patients with lumbar intervertebral disc protrusion and leads to pain. Whether the clinical curative effects of acupuncture in the treatment of lumbar and leg pain are linked to an inhibition of local IL-1 secretion is unknown. OBJECTIVE： To assess the influence of acupuncture on IL-1, this study was designed to verify the effects of acupuncture at the ＂Huatuojiaji （Extra）＂ point on the nerve root in a rat model of lumbar nerve root compression, compared with administration of meloxicam, a non-steroidal anti-inflammatory drug. DESIGN, TIME AND SETTING： Randomized, controlled, molecular biology experiment, performed at the Experimental Center, Sixth People’s Hospital Affiliated to Shanghai Jiao Tong University between September 2005 and April 2006. MATERIALS： Forty healthy adult Sprague Dawley rats of either gender were included in this study. The rats were randomly and evenly divided into the following four groups： normal control, model, acupuncture and meloxicam groups. Lumbar nerve root compression was induced in rats in the model, acupuncture, and meloxicam groups by inserting a specially made silicon rubber slice at the juncture of the L5 nerve root and the dural sac. The acupuncture needle （pattern number N3030, 30#, 1.5 inch） was purchased from Suzhou Medical Appliance Factory, China. IL-1 enzyme linked immunosorbent assay （ELISA） kit was purchased from Santa Cruz Biotechnology, Inc., USA. METHODS： The acupuncture group was acupunctured at the ＂Huatuojiaji＂ point, which is lateral to the compressed L5-6 nerve root, with an acupuncture depth of 0.5 cm. There were two treatment courses, each of involved seven 20-minute acupuncture sessions, one session a day. The meloxicam group was administered intragastrically 3.75 mg/kg meloxicam （5 mg meloxicam /10 mL physiological saline）. Rats in the normal control group and model group received an intragastric administration of 10 mL/kg physiological saline. All administrations were performed once a day. MAIN OUTCOME MEASURES： At day 14 post-surgery, the IL-1 level in the compressed nerve root was determined by a streptavidin-peroxidase （S-P） immunohistochemical method, and IL-1β mRNA expression in the compressed nerve root was simultaneously detected by real-time reverse transcription-polymerase chain reaction. RESULTS： The expression levels of IL-1 and IL-1β mRNA in the L5 nerve root were significantly higher in the model group than in the control group （P 〈 0.01）. However, the expression levels of IL-1 and IL-1β mRNA were significantly lower in the acupuncture and meloxicam groups than in the model group （P 〈 0.05–0.01）. Expression levels of IL-1 and IL-1β mRNA were significantly higher in the acupuncture group than in the meloxicam group （P 〈 0.01）. CONCLUSION： Acupuncture at the ＂Huatuojiaji＂ point decreases the IL-1 level by inhibiting IL-1β mRNA expression to a greater extent than meloxicam administration.
文摘A number of statistical tests are proposed for the purpose of change-point detection in a general nonparametric regression model under mild conditions. New proofs are given to prove the weak convergence of the underlying processes which assume remove the stringent condition of bounded total variation of the regression function and need only second moments. Since many quantities, such as the regression function, the distribution of the covariates and the distribution of the errors, are unspecified, the results are not distribution-free. A weighted bootstrap approach is proposed to approximate the limiting distributions. Results of a simulation study for this paper show good performance for moderate samples sizes.
基金Supported by National Natural Science Foundation of China(Grant Nos.51635002(Key Program),51605011,51275015)
文摘Joint clearances in antenna pointing mechanisms lead to uncertainty in function deviation. Current studies mainly focus on radial clearance of revolute joints, while axial clearance has rarely been taken into consideration. In fact, own?ing to errors from machining and assembly, thermal deformation and so forth, practically, axial clearance is inevitable in the joint. In this study, an error equivalent model(EEM) of revolute joints is proposed with considering both radial and axial clearances. Compared to the planar model of revolute joints only considering radial clearance, the journal motion inside the bearing is more abundant and matches the reality better in the EEM. The model is also extended for analyzing the error distribution of a spatial dual?axis("X–Y" type) antenna pointing mechanism of Spot?beam antennas which especially demand a high pointing accuracy. Three case studies are performed which illustrates the internal relation between radial clearance and axial clearance. It is found that when the axial clearance is big enough, the physical journal can freely realize both translational motion and rotational motion. While if the axial clearance is limited, the motion of the physical journal will be restricted. Analysis results indicate that the consideration of both radial and axial clearances in the revolute joint describes the journal motion inside the bearing more precise. To further validate the proposed model, a model of the EEM is designed and fabricated. Some suggestions on the design of revolute joints are also provided.
基金Projects(59375211,10771178,10676031) supported by the National Natural Science Foundation of ChinaProject(07A068) supported by the Key Project of Hunan Education CommissionProject(2005CB321702) supported by the National Key Basic Research Program of China
文摘The internal turbulent flow in conical diffuser is a very complicated adverse pressure gradient flow.DLR k-ε turbulence model was adopted to study it.The every terms of the Laplace operator in DLR k-ε turbulence model and pressure Poisson equation were discretized by upwind difference scheme.A new full implicit difference scheme of 5-point was constructed by using finite volume method and finite difference method.A large sparse matrix with five diagonals was formed and was stored by three arrays of one dimension in a compressed mode.General iterative methods do not work wel1 with large sparse matrix.With algebraic multigrid method(AMG),linear algebraic system of equations was solved and the precision was set at 10-6.The computation results were compared with the experimental results.The results show that the computation results have a good agreement with the experiment data.The precision of computational results and numerical simulation efficiency are greatly improved.
基金supported by the Instrument Developing Project of the Chinese Academy of Sciences (Grant No.YJKYYQ20190044)the National Key Research and Development Program of China (Grant No.2022YFB3903100)+1 种基金the High-level introduction of talent research start-up fund of Hefei Normal University in 2020 (Grant No.2020rcjj34)the HFIPS Director’s Fund (Grant No.YZJJ2022QN12).
文摘Non-line-of-sight(NLOS)imaging has emerged as a prominent technique for reconstructing obscured objects from images that undergo multiple diffuse reflections.This imaging method has garnered significant attention in diverse domains,including remote sensing,rescue operations,and intelligent driving,due to its wide-ranging potential applications.Nevertheless,accurately modeling the incident light direction,which carries energy and is captured by the detector amidst random diffuse reflection directions,poses a considerable challenge.This challenge hinders the acquisition of precise forward and inverse physical models for NLOS imaging,which are crucial for achieving high-quality reconstructions.In this study,we propose a point spread function(PSF)model for the NLOS imaging system utilizing ray tracing with random angles.Furthermore,we introduce a reconstruction method,termed the physics-constrained inverse network(PCIN),which establishes an accurate PSF model and inverse physical model by leveraging the interplay between PSF constraints and the optimization of a convolutional neural network.The PCIN approach initializes the parameters randomly,guided by the constraints of the forward PSF model,thereby obviating the need for extensive training data sets,as required by traditional deep-learning methods.Through alternating iteration and gradient descent algorithms,we iteratively optimize the diffuse reflection angles in the PSF model and the neural network parameters.The results demonstrate that PCIN achieves efficient data utilization by not necessitating a large number of actual ground data groups.Moreover,the experimental findings confirm that the proposed method effectively restores the hidden object features with high accuracy.
文摘The effect of rotation on the shape (figure) and gravitational quadrupole of astronomical bodies is calculated by using an approximate point core model: A point mass at the center of an ellipsoidal homogeneous fluid. Maclaurin’s analytical result for homogenous bodies generalizes to this model and leads to very accurate analytical results connecting the three observables: oblateness (ò), gravitational quadrupole (J2), and angular velocity parameter (q). The analytical results are compared to observational data for the planets and a good agreement is found. Oscillations near equilibrium are studied within the model.
文摘[Objective]The study aimed to simulate the production and transportation process of surface runoff,sediment and non-point source pollution in Xincai River basin based on SWAT model.[Method]On the basis of analyzing the principles of SWAT model,the correlative parameters of runoff,sediment and water quality were calibrated,then the spatial and temporal distribution of runoff,sediment and non-point source pollutants in Xincai River basin were studied by using SWAT model.[Result]The results of calibration and validation showed that SWAT model was reasonable and available,and it can be used to simulate the non-point source pollution of Xincai River basin.The simulation results revealed that the load of sediment and various pollutants was the highest in the rainy year,followed by the normal year,while it was the minimum in the dry year,indicating that the production of sediment and non-point source pollutants was closely related to annual runoff.[Conclusion]The research could provide scientific references for the prevention of non-point source pollution in a basin.
基金Supported by National Natural Science Foundation of China(Grant No.11372036)
文摘Reduced order models(ROMs) based on the snapshots on the CFD high-fidelity simulations have been paid great attention recently due to their capability of capturing the features of the complex geometries and flow configurations. To improve the efficiency and precision of the ROMs, it is indispensable to add extra sampling points to the initial snapshots, since the number of sampling points to achieve an adequately accurate ROM is generally unknown in prior, but a large number of initial sampling points reduces the parsimony of the ROMs. A fuzzy-clustering-based adding-point strategy is proposed and the fuzzy clustering acts an indicator of the region in which the precision of ROMs is relatively low. The proposed method is applied to construct the ROMs for the benchmark mathematical examples and a numerical example of hypersonic aerothermodynamics prediction for a typical control surface. The proposed method can achieve a 34.5% improvement on the efficiency than the estimated mean squared error prediction algorithm and shows same-level prediction accuracy.
