Aim To study properties of solutions to a class of second order differential inequality with continuous distributed deviating arguments. Methods A direct analysis technique was used. Results and Conclusion Some suf...Aim To study properties of solutions to a class of second order differential inequality with continuous distributed deviating arguments. Methods A direct analysis technique was used. Results and Conclusion Some sufficient conditions that ensure a class of second order delay differential inequality having no eventually positive solutions were obtained, which generalized some given results. Using the results, some oscillatory criteria for solutions of the hyperbolic equation with distributed deviating arguments can be established.展开更多
In this paper,a nonconforming rectangular plate element,the modified incomplete biquadratic plate element,is considered. The asympotic optimal L~∞-error estimate is obtained for the plate bending problem. This proof ...In this paper,a nonconforming rectangular plate element,the modified incomplete biquadratic plate element,is considered. The asympotic optimal L~∞-error estimate is obtained for the plate bending problem. This proof is based on the method of regularized Green's function and 'the trick of auxiliary element'.展开更多
A new control law is proposed to asymptotically stabilize the chaotic neuron system based on LaSalleinvariant principle.The control technique does not require analytical knowledge of the system dynamics and operateswi...A new control law is proposed to asymptotically stabilize the chaotic neuron system based on LaSalleinvariant principle.The control technique does not require analytical knowledge of the system dynamics and operateswithout an explicit knowledge of the desired steady-state position.The well-known modified Hodgkin-Huxley (MHH)and Hindmarsh-Rose (HR) model neurons are taken as examples to verify the implementation of our method.Simulationresults show the proposed control law is effective.The outcome of this study is significant since it is helpful to understandthe learning process of a human brain towards the information processing,memory and abnormal discharge of the brainneurons.展开更多
In practical engineering,only pressure sensors are allowed to install to detect leakage in most of oil transportation pipelines,while flowmeters are only installed at the toll ports.For incompressible fluid,the leakag...In practical engineering,only pressure sensors are allowed to install to detect leakage in most of oil transportation pipelines,while flowmeters are only installed at the toll ports.For incompressible fluid,the leakage rate and amount cannot be accurately calculated through critical pressure conditions.In this paper,a micro-element body of the pipeline was intercepted for calculation.The relationship between radial displacement and pressure of pipe wall was studied based on the stress-strain equation.Then,the strain response of pipeline volume with pipeline pressure was obtained.The change in volume expansion of pipeline was used to characterize leakage of incompressible fluid.Finally,the calculation model of leakage amount of incompressible fluid was obtained.To verify the above theory,the pipeline expansion model under pressure was established by COMSOL software for simulation.Both simulation results and deduction equations show that the volumetric change has a quadratic parabolic relationship with the change of pipeline pressure.However,the relationship between them can be approximately linear when the pressure change is not too large.In addition,the leakage of incompressible fluid under the pressure of 0 MPa-0.8 MPa was obtained by experiments.The experimental results verify the linear relationship between leakage of incompressible fluid and the change of pipeline pressure.The theoretical and experimental results provide a basis for the calculation of leakage of incompressible fluid in the pipeline.展开更多
Cold orbital forging is an advanced spur bevel gear forming technology. Generally, the spur bevel gear in the cold orbital forging process is formed by two steps: the preforming step and the final step. Due to the gre...Cold orbital forging is an advanced spur bevel gear forming technology. Generally, the spur bevel gear in the cold orbital forging process is formed by two steps: the preforming step and the final step. Due to the great importance of the final step to gear forming and its complication with interactive factors, this work aims at examining the influence of key factors on the final step in cold orbital forging of a spur bevel gear. Using the finite element(FE) method and control variate method, the influence rules of four key factors, rotation velocity of the upper tool, n, feeding velocity of the lower tool, v, tilted angle of the upper tool, γ, friction factor between the tools and the billet, m, on the geometry and the deformation inhomogeneity of the cold orbital forged gear are thoroughly clarified. The research results show that the flash becomes more homogeneous with increasing v, increasing m, decreasing n or decreasing γ. And the deformation of the gear becomes more homogeneous with increasing v, decreasing n or decreasing γ. Finally, a corresponding experiment is conducted, which verifies the accuracy of FE simulation conclusions.展开更多
Objective The accurate diagnosis of the non-specific variant of dysembryoplastic neuroepithelial tumor （DNT） is very difficult because it is characterized by absence of the histological hallmark of the ＂specific gl...Objective The accurate diagnosis of the non-specific variant of dysembryoplastic neuroepithelial tumor （DNT） is very difficult because it is characterized by absence of the histological hallmark of the ＂specific glioneuronal element＂ in lesions. We herein present two cases of the non-specific form of DNT to analyze the clinical, radiological, and histological features of this unusual subtype of DNT. Methods A 16-year-old and a 23-year-old patient had been treated for pharmacoresistant epilepsy for several years before undergoing referral to the hospital for further examination and treatment. Magnetic resonance imaging （MRI） revealed that both patients had a small, well-demarcated cystic lesion within the cortex of the brain without obvious contrast enhancement or peritumoral edema. The lesions were totally resected and routinely examined using histological and immunohistochemical analysis. Results Both lesions exhibited similar histological appearances with cyst formation and mural nodule architecture. The glial nodules were mainly composed of oligodendrocyte-like components, and partly of pi^oid cells resembling pilocytic astrocytoma. The cortex adjacent to the lesion in both cases was found to have the histological features of focal cortical dysplasia （FCD） Type I. Immunohistochemically, the oligoden- drocyte-like components were diffusely positive for Syn and Olig-2, but staining for CD34, p53, and IDH1 R132H was negative. The Ki-67 （MIB-1） labeling index was low, approximately 1%. There was no 1p/19q co-deletion in either lesion by fluorescence in situ hybridization （FISH） assay. Neither patient received postoperative adjuvant treatment, and both underwent regular follow-up for at least 24 months. No signs of recurrence or epileptic attacks were observed during the follow-up period. Conclusion The non-specific variant of DNT is a diagnostic challenge for pathologists in clinical practice, and differentiation from some low-grade gliomas needs to be considered. The careful inspection of radio- logic and histopathologic findings, accompanied by analysis of patients＇ clinical manifestations, may be helpful in making an accurate diagnosis.展开更多
Let V be a vector space over a field F and G a group of linear transformations in V. It is proved in this note that for any subspace U (V, if dimU/(U∩ g(U))≤ 1, for any g∈G, then there is a g∈ G such that U∩g(U) ...Let V be a vector space over a field F and G a group of linear transformations in V. It is proved in this note that for any subspace U (V, if dimU/(U∩ g(U))≤ 1, for any g∈G, then there is a g∈ G such that U∩g(U) is a G-invariant subspace, or there is an x∈ V\U such that U + <x> is a G-invariant subspace. So a vector-space analog of Brailovsky's results on quasi-invariant sets is given.展开更多
文摘Aim To study properties of solutions to a class of second order differential inequality with continuous distributed deviating arguments. Methods A direct analysis technique was used. Results and Conclusion Some sufficient conditions that ensure a class of second order delay differential inequality having no eventually positive solutions were obtained, which generalized some given results. Using the results, some oscillatory criteria for solutions of the hyperbolic equation with distributed deviating arguments can be established.
文摘In this paper,a nonconforming rectangular plate element,the modified incomplete biquadratic plate element,is considered. The asympotic optimal L~∞-error estimate is obtained for the plate bending problem. This proof is based on the method of regularized Green's function and 'the trick of auxiliary element'.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 10862001 and 10947011the Construction of Key Laboratories in Universities of Guangxi under Grant No. 200912
文摘A new control law is proposed to asymptotically stabilize the chaotic neuron system based on LaSalleinvariant principle.The control technique does not require analytical knowledge of the system dynamics and operateswithout an explicit knowledge of the desired steady-state position.The well-known modified Hodgkin-Huxley (MHH)and Hindmarsh-Rose (HR) model neurons are taken as examples to verify the implementation of our method.Simulationresults show the proposed control law is effective.The outcome of this study is significant since it is helpful to understandthe learning process of a human brain towards the information processing,memory and abnormal discharge of the brainneurons.
文摘In practical engineering,only pressure sensors are allowed to install to detect leakage in most of oil transportation pipelines,while flowmeters are only installed at the toll ports.For incompressible fluid,the leakage rate and amount cannot be accurately calculated through critical pressure conditions.In this paper,a micro-element body of the pipeline was intercepted for calculation.The relationship between radial displacement and pressure of pipe wall was studied based on the stress-strain equation.Then,the strain response of pipeline volume with pipeline pressure was obtained.The change in volume expansion of pipeline was used to characterize leakage of incompressible fluid.Finally,the calculation model of leakage amount of incompressible fluid was obtained.To verify the above theory,the pipeline expansion model under pressure was established by COMSOL software for simulation.Both simulation results and deduction equations show that the volumetric change has a quadratic parabolic relationship with the change of pipeline pressure.However,the relationship between them can be approximately linear when the pressure change is not too large.In addition,the leakage of incompressible fluid under the pressure of 0 MPa-0.8 MPa was obtained by experiments.The experimental results verify the linear relationship between leakage of incompressible fluid and the change of pipeline pressure.The theoretical and experimental results provide a basis for the calculation of leakage of incompressible fluid in the pipeline.
基金Project(51105287)supported by the National Natural Science Foundation of ChinaProject(IRT13087)supported by Innovative Research Team Development Program of Ministry of Education of China+2 种基金Project(2012-86)supported by High-End Talent Leading Program of Hubei Province,ChinaProject(2014CFB876)supported by Natural Science Foundation of Hubei ProvinceChina
文摘Cold orbital forging is an advanced spur bevel gear forming technology. Generally, the spur bevel gear in the cold orbital forging process is formed by two steps: the preforming step and the final step. Due to the great importance of the final step to gear forming and its complication with interactive factors, this work aims at examining the influence of key factors on the final step in cold orbital forging of a spur bevel gear. Using the finite element(FE) method and control variate method, the influence rules of four key factors, rotation velocity of the upper tool, n, feeding velocity of the lower tool, v, tilted angle of the upper tool, γ, friction factor between the tools and the billet, m, on the geometry and the deformation inhomogeneity of the cold orbital forged gear are thoroughly clarified. The research results show that the flash becomes more homogeneous with increasing v, increasing m, decreasing n or decreasing γ. And the deformation of the gear becomes more homogeneous with increasing v, decreasing n or decreasing γ. Finally, a corresponding experiment is conducted, which verifies the accuracy of FE simulation conclusions.
文摘Objective The accurate diagnosis of the non-specific variant of dysembryoplastic neuroepithelial tumor （DNT） is very difficult because it is characterized by absence of the histological hallmark of the ＂specific glioneuronal element＂ in lesions. We herein present two cases of the non-specific form of DNT to analyze the clinical, radiological, and histological features of this unusual subtype of DNT. Methods A 16-year-old and a 23-year-old patient had been treated for pharmacoresistant epilepsy for several years before undergoing referral to the hospital for further examination and treatment. Magnetic resonance imaging （MRI） revealed that both patients had a small, well-demarcated cystic lesion within the cortex of the brain without obvious contrast enhancement or peritumoral edema. The lesions were totally resected and routinely examined using histological and immunohistochemical analysis. Results Both lesions exhibited similar histological appearances with cyst formation and mural nodule architecture. The glial nodules were mainly composed of oligodendrocyte-like components, and partly of pi^oid cells resembling pilocytic astrocytoma. The cortex adjacent to the lesion in both cases was found to have the histological features of focal cortical dysplasia （FCD） Type I. Immunohistochemically, the oligoden- drocyte-like components were diffusely positive for Syn and Olig-2, but staining for CD34, p53, and IDH1 R132H was negative. The Ki-67 （MIB-1） labeling index was low, approximately 1%. There was no 1p/19q co-deletion in either lesion by fluorescence in situ hybridization （FISH） assay. Neither patient received postoperative adjuvant treatment, and both underwent regular follow-up for at least 24 months. No signs of recurrence or epileptic attacks were observed during the follow-up period. Conclusion The non-specific variant of DNT is a diagnostic challenge for pathologists in clinical practice, and differentiation from some low-grade gliomas needs to be considered. The careful inspection of radio- logic and histopathologic findings, accompanied by analysis of patients＇ clinical manifestations, may be helpful in making an accurate diagnosis.
基金Supported by the National Natural Science Foundations of China !(19771014) and Liaoning Province! (972208)
文摘Let V be a vector space over a field F and G a group of linear transformations in V. It is proved in this note that for any subspace U (V, if dimU/(U∩ g(U))≤ 1, for any g∈G, then there is a g∈ G such that U∩g(U) is a G-invariant subspace, or there is an x∈ V\U such that U + <x> is a G-invariant subspace. So a vector-space analog of Brailovsky's results on quasi-invariant sets is given.
