As a common practice,a large hydro-generator will operate in leading phase conditions to absorb the reactive power of the power grid.However,the accurate and precise prediction of the leading phase operation capacity ...As a common practice,a large hydro-generator will operate in leading phase conditions to absorb the reactive power of the power grid.However,the accurate and precise prediction of the leading phase operation capacity of a large hydro-generator has always been a formidable challenge to engineers and academicians because it is extremely hard to compute the eddy currents and losses as well as the local overheating in the pressure plate and finger.To address this problem,a full three dimensional(3D)finite element model and method of the coupled eddy current and temperature fields in the end region of a large hydro-generator are developed.The equivalent medium parameters used in the computations are comprehensively discussed.Moreover,some numerically based solution methodologies for accurate computation of the field and armature currents under different leading phase conditions are proposed.Numerical results on the coupled eddy current and temperature fields in the end regions of a 250 MW hydro-generator confirm positively the feasibility of the present work.展开更多
Reliability of medical instruments such as hemostats is extremely important because these instruments are used in patients who are in critical condition. Clamping force of hemostats, as an important parameter of hemos...Reliability of medical instruments such as hemostats is extremely important because these instruments are used in patients who are in critical condition. Clamping force of hemostats, as an important parameter of hemostats, should be detected. However, it could not be tested directly. In order to test it, a testing system has been put forward. The system is comprised of sensor, acquisition card, and three-way tap and so on. This system is controlled by a computer. The testing system has been proved to be effective in testing the clamping force of hemostats.展开更多
Background To compare the preventive effects of levetiracetam and valproate on late-onset post-traumatic seizures in patients with traumatic brain injury(TBI).Methods A total of 95 patients with TBI were recruited fro...Background To compare the preventive effects of levetiracetam and valproate on late-onset post-traumatic seizures in patients with traumatic brain injury(TBI).Methods A total of 95 patients with TBI were recruited from 2017 to 2020.They were randomized into three groups:levetiracetam(LEV)group(n=30)receiving LEV treatment(500 mg,bid,po);valproate group(n=32)receiving sodium valproate(500 mg/d,once daily,po);and control group(n=33)receiving no anti-seizure medication.LEV and valproate were given to corresponding groups within seven days after TBI,and the administration lasted for one month.The incidence of epilepsy and adverse events were evaluated at 7 days and 12 months post-TBI.Results The cumulative incidences of late post-traumatic seizures at the 12-month follow-up in the LEV,valproate,and control groups were 3.33%,12.50%and 15.63%,respectively.The cumulative incidence of late post-traumatic seizures in the LEV group was significantly lower than those in the valproate and control groups(P<0.05).The cumulative incidence of late post-traumatic seizure in the valproate group was not significantly different from that in the control group(P>0.05).Conclusions LEV can reduce the cumulative incidence of late post-traumatic seizures,whereas valproate can not.展开更多
Defect factors and their relevant rules can be analyzed in depth by processing defect records which are often expressed in the form of text data.However,considering that defect text consists of both structured and uns...Defect factors and their relevant rules can be analyzed in depth by processing defect records which are often expressed in the form of text data.However,considering that defect text consists of both structured and unstructured data,it is necessary to excavate structured information from unstructured data.In this paper,a text mining method based on semantic framework technology is introduced to transform unstructured defect description into structured information such as components and defect attributes.Then,a deep analyzing model of a power equipment defect is established,which provides a scheme of defect mining based on historical defect texts.Case studies prove that the proposed deep analysis method has a guiding significance for equipment upgrading,selection and maintenance.展开更多
In order to recover the value of short texts in the operation and maintenance of power equipment,a short text mining framework with specific design is proposed.First,the process of the short text mining framework is s...In order to recover the value of short texts in the operation and maintenance of power equipment,a short text mining framework with specific design is proposed.First,the process of the short text mining framework is summarized,in which the functions of all the processing modules are introduced.Then,according to the characteristics of short texts in the operation and maintenance of power equipment,the specific design for each module is proposed,which adapts the short text mining framework to a practical application.Finally,based on the framework with the specific designed modules,two examples in terms of defect texts are given to illustrate the application of short text mining in the operation and maintenance of power equipment.The results of the examples show that the short text mining framework is suitable for operation and maintenance tasks for power equipment,and the specific design for each module is beneficial for the improvement of the application effect.展开更多
The effective identifications of important nodes in power grid are foundations of differentiated management and stable operation of power grid. However, the current studies on this field are not thorough enough. This ...The effective identifications of important nodes in power grid are foundations of differentiated management and stable operation of power grid. However, the current studies on this field are not thorough enough. This paper applies the model based on co-citation(MBCC)-hypertext induced topic selection(HITS) algorithm used in web page ranking to power grid and proposes an index to determine node importance of power grid from the perspectives of inflow and outflow power. MBCC-HITS algorithm is modified considering load, power source, and line flow comprehensively for the differences between Internet and power grid in this paper. Then a method for evaluating node importance is proposed using the modified algorithm. Lastly, the rationality and validity of the proposed method are verified by comparisons with other methods in case studies of IEEE 14-bus and 118-bus systems.展开更多
Biodegradable chitosan(CS)films can meet the demand for sustainable development.However,the performance of pure CS membrane still exists a particular gap compared with the traditional film.Inorganic nanomaterials with...Biodegradable chitosan(CS)films can meet the demand for sustainable development.However,the performance of pure CS membrane still exists a particular gap compared with the traditional film.Inorganic nanomaterials with the controllable release are added to improve its physical and chemical properties.Herein,a series of CS/phosphate-stabilized amorphous calcium carbonate(CS/ACCP)and CS/sodium alginate/ACCP(CS/Alginate/ACCP)composite films were prepared by the flow method.The effects of ACCP and Alginate/ACCP nanoparticles on the physical and chemical properties of the composite membrane were investigated.The results showed that the composite nanoparticles could significantly improve CS film’s compactness,hydrophobicity,and mechanical properties and enhance its ultraviolet(UV)blocking ability,water resistance,and water vapor blocking ability.When the number of nanoparticles was 8%,the mechanical properties of the CS composite membrane reached optimum value,and the comprehensive performance was better.In addition,the controlled-release properties of CS composite membranes were also studied,and the antioxidant,antibacterial,biocompatibility,and fresh-keeping effects of the composite membranes were explored.The results indicated that the CS composite membranes had not only excellent bacteriostatic(72%)properties(Escherichia coli)but also presented well fruit preservation(15 days)properties(sugar orange).In particular,the controlled release range of CS composite membrane at 12 h was between 30%and 90%,which provided a theoretical basis for its use as an edible membrane.Therefore,based on ACCP and Alginate/ACCP nanoparticles,CS composite membranes with more excellent application value in the biological field were prepared through further optimization design.展开更多
Background:Spinal cord injury(SCI)remains a high rate of disability.In order to improve the quality of their lives,the application of robots in rehabilitation is increasing.However,few studies have assessed the applic...Background:Spinal cord injury(SCI)remains a high rate of disability.In order to improve the quality of their lives,the application of robots in rehabilitation is increasing.However,few studies have assessed the applicability and the effect of robots in patients with complete injury.Objective:The current study aims to assess the efficacy of robots training on the lower extremity physiology in complete SCI patients.Methods:24 patients were recruited and randomly divided into experimental and control group.The two groups spent the same amount of time on regular training.Besides,a 1-h standing training twice daily was offered to both groups five days per week,for four weeks.The experimental group used robot for standing training,while the control group used standing frame.Before and after the experiment,muscle girth and bone mineral density(BMD)were measured as lower extremity physiology.Results:The experimental group showed increased muscle girth differences(left=0.08±0.40 cm,right=0.75±0.72 cm),while the control group showed decreased girth differences(left=-0.78±0.54 cm,right=-0.56±0.54 cm).The increases in the experimental group showed significant differences compared with the control group(left,P=0.0002;right,P=0.023).Both groups showed decreased BMD.The decreases in the experimental group were significantly smaller than those in the control group.Conclusions:Training with aid of robots combined with the regular rehabilitation treatment can benefit complete SCI patients,in aspect of postponing amyotrophy of lower extremities and reducing bone loss and osteoporosis.展开更多
Secretory phospholipase A2s(sPLA2s)are found in a wide range of organisms from bacteria to higher plants and animals and are involved in varied and cellular pro-cesses.However,roles of these enzymes in microbial patho...Secretory phospholipase A2s(sPLA2s)are found in a wide range of organisms from bacteria to higher plants and animals and are involved in varied and cellular pro-cesses.However,roles of these enzymes in microbial pathogens remain unclear.Here,an sPLA2(BbPLA2)was characterized in the filamentous insect pathogenic fungus,Beau-veria bassiana.BbPLA2was exclusively expressed in insect hemolymph-derived cells(hyphal bodies),and its expression was induced by insect-derived nutrients and lipids,and nutrient starvation.High levels of secretion of BbPLA2 were observed as well as its distri-bution in hyphal body lipid drops(LDs).Overexpression of BbPLA2 increased the ability of B.bassiana to utilize insect-derived nutrients and lipids,and promoted LD accumula-tion,indicating functions for BbPLA2 in mediating LD homeostasis and assimilation of insect-derived lipids.Strains overexpressing BbPLA2 showed moderately increased vir-ulence,including more efficient penetration of the insect cuticle and evasion of host im-mune responses as compared to the wild type strain.In addition,B.bassiana-activated host immune genes were downregulated in the BbPLA2 overexpression strain,but upregulated by infections with a△BbPLA2 strain.These data demonstrate that BbPLA2 contributes to LD homeostasis,assimilation of insect-derived lipids,and repression of host immune responses.展开更多
文摘As a common practice,a large hydro-generator will operate in leading phase conditions to absorb the reactive power of the power grid.However,the accurate and precise prediction of the leading phase operation capacity of a large hydro-generator has always been a formidable challenge to engineers and academicians because it is extremely hard to compute the eddy currents and losses as well as the local overheating in the pressure plate and finger.To address this problem,a full three dimensional(3D)finite element model and method of the coupled eddy current and temperature fields in the end region of a large hydro-generator are developed.The equivalent medium parameters used in the computations are comprehensively discussed.Moreover,some numerically based solution methodologies for accurate computation of the field and armature currents under different leading phase conditions are proposed.Numerical results on the coupled eddy current and temperature fields in the end regions of a 250 MW hydro-generator confirm positively the feasibility of the present work.
文摘Reliability of medical instruments such as hemostats is extremely important because these instruments are used in patients who are in critical condition. Clamping force of hemostats, as an important parameter of hemostats, should be detected. However, it could not be tested directly. In order to test it, a testing system has been put forward. The system is comprised of sensor, acquisition card, and three-way tap and so on. This system is controlled by a computer. The testing system has been proved to be effective in testing the clamping force of hemostats.
基金funded by the Scientific Research Fund of China Association Against Epilepsy(No 2012002).
文摘Background To compare the preventive effects of levetiracetam and valproate on late-onset post-traumatic seizures in patients with traumatic brain injury(TBI).Methods A total of 95 patients with TBI were recruited from 2017 to 2020.They were randomized into three groups:levetiracetam(LEV)group(n=30)receiving LEV treatment(500 mg,bid,po);valproate group(n=32)receiving sodium valproate(500 mg/d,once daily,po);and control group(n=33)receiving no anti-seizure medication.LEV and valproate were given to corresponding groups within seven days after TBI,and the administration lasted for one month.The incidence of epilepsy and adverse events were evaluated at 7 days and 12 months post-TBI.Results The cumulative incidences of late post-traumatic seizures at the 12-month follow-up in the LEV,valproate,and control groups were 3.33%,12.50%and 15.63%,respectively.The cumulative incidence of late post-traumatic seizures in the LEV group was significantly lower than those in the valproate and control groups(P<0.05).The cumulative incidence of late post-traumatic seizure in the valproate group was not significantly different from that in the control group(P>0.05).Conclusions LEV can reduce the cumulative incidence of late post-traumatic seizures,whereas valproate can not.
文摘Defect factors and their relevant rules can be analyzed in depth by processing defect records which are often expressed in the form of text data.However,considering that defect text consists of both structured and unstructured data,it is necessary to excavate structured information from unstructured data.In this paper,a text mining method based on semantic framework technology is introduced to transform unstructured defect description into structured information such as components and defect attributes.Then,a deep analyzing model of a power equipment defect is established,which provides a scheme of defect mining based on historical defect texts.Case studies prove that the proposed deep analysis method has a guiding significance for equipment upgrading,selection and maintenance.
文摘In order to recover the value of short texts in the operation and maintenance of power equipment,a short text mining framework with specific design is proposed.First,the process of the short text mining framework is summarized,in which the functions of all the processing modules are introduced.Then,according to the characteristics of short texts in the operation and maintenance of power equipment,the specific design for each module is proposed,which adapts the short text mining framework to a practical application.Finally,based on the framework with the specific designed modules,two examples in terms of defect texts are given to illustrate the application of short text mining in the operation and maintenance of power equipment.The results of the examples show that the short text mining framework is suitable for operation and maintenance tasks for power equipment,and the specific design for each module is beneficial for the improvement of the application effect.
基金supported by State Grid Technology Project(No.GY71-14-075)
文摘The effective identifications of important nodes in power grid are foundations of differentiated management and stable operation of power grid. However, the current studies on this field are not thorough enough. This paper applies the model based on co-citation(MBCC)-hypertext induced topic selection(HITS) algorithm used in web page ranking to power grid and proposes an index to determine node importance of power grid from the perspectives of inflow and outflow power. MBCC-HITS algorithm is modified considering load, power source, and line flow comprehensively for the differences between Internet and power grid in this paper. Then a method for evaluating node importance is proposed using the modified algorithm. Lastly, the rationality and validity of the proposed method are verified by comparisons with other methods in case studies of IEEE 14-bus and 118-bus systems.
基金The work was financially supported by the National Natural Science Foundation of China(31700689)Natural Science Foundation of Shanxi Province(201901D111115)+2 种基金Supported by Transformation of Scientific and Technological Achievements Programs of Higher Education Institutions in Shanxi(2020CG015)Key Technology Research and Development Plan of Jinzhong City in Shanxi(Y201022)Liuwei Zhai Food Research Institute,Taiyuan University of Technology(213020310-J).
文摘Biodegradable chitosan(CS)films can meet the demand for sustainable development.However,the performance of pure CS membrane still exists a particular gap compared with the traditional film.Inorganic nanomaterials with the controllable release are added to improve its physical and chemical properties.Herein,a series of CS/phosphate-stabilized amorphous calcium carbonate(CS/ACCP)and CS/sodium alginate/ACCP(CS/Alginate/ACCP)composite films were prepared by the flow method.The effects of ACCP and Alginate/ACCP nanoparticles on the physical and chemical properties of the composite membrane were investigated.The results showed that the composite nanoparticles could significantly improve CS film’s compactness,hydrophobicity,and mechanical properties and enhance its ultraviolet(UV)blocking ability,water resistance,and water vapor blocking ability.When the number of nanoparticles was 8%,the mechanical properties of the CS composite membrane reached optimum value,and the comprehensive performance was better.In addition,the controlled-release properties of CS composite membranes were also studied,and the antioxidant,antibacterial,biocompatibility,and fresh-keeping effects of the composite membranes were explored.The results indicated that the CS composite membranes had not only excellent bacteriostatic(72%)properties(Escherichia coli)but also presented well fruit preservation(15 days)properties(sugar orange).In particular,the controlled release range of CS composite membrane at 12 h was between 30%and 90%,which provided a theoretical basis for its use as an edible membrane.Therefore,based on ACCP and Alginate/ACCP nanoparticles,CS composite membranes with more excellent application value in the biological field were prepared through further optimization design.
基金supported by the National Natural Science Foundation of China(61761166002).
文摘Background:Spinal cord injury(SCI)remains a high rate of disability.In order to improve the quality of their lives,the application of robots in rehabilitation is increasing.However,few studies have assessed the applicability and the effect of robots in patients with complete injury.Objective:The current study aims to assess the efficacy of robots training on the lower extremity physiology in complete SCI patients.Methods:24 patients were recruited and randomly divided into experimental and control group.The two groups spent the same amount of time on regular training.Besides,a 1-h standing training twice daily was offered to both groups five days per week,for four weeks.The experimental group used robot for standing training,while the control group used standing frame.Before and after the experiment,muscle girth and bone mineral density(BMD)were measured as lower extremity physiology.Results:The experimental group showed increased muscle girth differences(left=0.08±0.40 cm,right=0.75±0.72 cm),while the control group showed decreased girth differences(left=-0.78±0.54 cm,right=-0.56±0.54 cm).The increases in the experimental group showed significant differences compared with the control group(left,P=0.0002;right,P=0.023).Both groups showed decreased BMD.The decreases in the experimental group were significantly smaller than those in the control group.Conclusions:Training with aid of robots combined with the regular rehabilitation treatment can benefit complete SCI patients,in aspect of postponing amyotrophy of lower extremities and reducing bone loss and osteoporosis.
基金supported by a grant from the National Nature Science Foundation of China(31672080)。
文摘Secretory phospholipase A2s(sPLA2s)are found in a wide range of organisms from bacteria to higher plants and animals and are involved in varied and cellular pro-cesses.However,roles of these enzymes in microbial pathogens remain unclear.Here,an sPLA2(BbPLA2)was characterized in the filamentous insect pathogenic fungus,Beau-veria bassiana.BbPLA2was exclusively expressed in insect hemolymph-derived cells(hyphal bodies),and its expression was induced by insect-derived nutrients and lipids,and nutrient starvation.High levels of secretion of BbPLA2 were observed as well as its distri-bution in hyphal body lipid drops(LDs).Overexpression of BbPLA2 increased the ability of B.bassiana to utilize insect-derived nutrients and lipids,and promoted LD accumula-tion,indicating functions for BbPLA2 in mediating LD homeostasis and assimilation of insect-derived lipids.Strains overexpressing BbPLA2 showed moderately increased vir-ulence,including more efficient penetration of the insect cuticle and evasion of host im-mune responses as compared to the wild type strain.In addition,B.bassiana-activated host immune genes were downregulated in the BbPLA2 overexpression strain,but upregulated by infections with a△BbPLA2 strain.These data demonstrate that BbPLA2 contributes to LD homeostasis,assimilation of insect-derived lipids,and repression of host immune responses.