Cytoplasmic accumulation of TDP-43 is a pathological hallmark of amyotrophic lateral sclerosis(ALS)and other neurodegenerative diseases.While current studies have primarily focused on gene regulation mediated by full-...Cytoplasmic accumulation of TDP-43 is a pathological hallmark of amyotrophic lateral sclerosis(ALS)and other neurodegenerative diseases.While current studies have primarily focused on gene regulation mediated by full-length nuclear TDP-43,the potential effects of cytoplasmic TDP-43 fragments remain less explored.Our previous findings demonstrated that primate-specific cleavage of TDP-43 contributes to its cytoplasmic localization,prompting further investigation into its pathological effects.In the cynomolgus monkey brain,we observed that mutant or truncated TDP-43 was transported onto the ribosome organelle.Ribosome-associated transcriptomic analysis revealed dysregulation of apoptosis-and lysosome-related genes,indicating that cytoplasmic TDP-43 induces neurotoxicity by binding to ribosomes and disrupting mRNA expression.These findings provide mechanistic insights into the gain-of-function effects of pathological TDP-43.展开更多
An online partial discharge(PD) measurement performed on a high voltage direct current(HVDC) wall bushing successfully identified the presence of internal discharges.The wall bushing is a sulfur hexafluoride gas-insul...An online partial discharge(PD) measurement performed on a high voltage direct current(HVDC) wall bushing successfully identified the presence of internal discharges.The wall bushing is a sulfur hexafluoride gas-insulated bushing,rated for 500 kV dc and terminated on a thyristor-controlled HVDC converter bridge.The measurement of PD within the HVDC station environment is particularly challenging due to the high levels of electromagnetic noise caused by thyristor switching events and external air-corona from the neighboring high-voltage equipment.An additional challenge is the""mixed"voltage stress on the bushing insulation,which has both ac and dc high-voltage components.There are also fast transients during the firing of thyristors in the HVDC conversion process that cause added stress to the insulation.As a result,the analysis and interpretation of PD data for HVDC equipment is more complex;PD pulses may occur in response to the ac,dc,or switching transient voltage stresses.In this paper,an online PD measurement strategy for noise filtering and isolation of PD sources within the bushing are discussed.The PD measurement data is plotted on a phase-resolved diagram where the line supply power cord voltage was used as a reference. The phase-resolved diagram appears to suggest that the fast transients,caused during switching,trigger some PD events.Measurements were also performed with the aid of a modern PD measurement instrument having noise separation capabilities.The findings from the online PD measurements are verified with physical evidence,found after the bushing was removed from service,suggested internal PD had occurred inside the bushing.展开更多
PartⅠhas illustrated the procedures to apply the Linkage Learning Genetic Algorithm(LLGA)in Gas Turbine Engine(GTE)controller gains tuning and generated the optimization results for runway conditions from idle to tak...PartⅠhas illustrated the procedures to apply the Linkage Learning Genetic Algorithm(LLGA)in Gas Turbine Engine(GTE)controller gains tuning and generated the optimization results for runway conditions from idle to takeoff.However,the total pressure and temperature of the engine inlet vary as the changing of altitude and Mach number,which would lead to the variation in fuel flow supply regulation.As a result,the optimized gains in runway might not be suitable for other flight conditions.In order to maintain the optimal control performance,the GTE controller gains should be adjusted according to the flight conditions.This paper extends the application of the LLGA method to other flight conditions and then simulates a complete flight mission with different gains and weather condition configurations.For this purpose,the control parameters in the Simulink model of the GTE controller are first corrected by the weather condition in altitude.Then,a typical flight mission is defined and divided into different flight segments based on the altitude and Mach number configuration.One representative point is selected from each segment as the datum point for optimization process.After this step,the LLGA method is used to find the best gains combinations for different flight conditions and the differences in optimization effects for different flight conditions are analyzed subsequently.The simulation results show that the optimization effect of the control performance of each flight condition is dependent on the value of(θδ)~(1/2)and the optimal K_(pla)in some flight conditions is approximately equal to p hd times of the Kplavalue in sea level standard condition.Finally,the complete flight mission is simulated with different gains and weather condition configurations.The simulation results show that the engine performance has been greatly improved after optimization by LLGA in the transient state and the high altitude conditions.In other steady states,the optimization effect is not very obvious.展开更多
This paper proposes a Linkage Learning Genetic Algorithm(LLGA)based on the messy Genetic Algorithm(mGA)to optimize the Min-Max fuel controller performance in Gas Turbine Engine(GTE).For this purpose,a GTE fuel control...This paper proposes a Linkage Learning Genetic Algorithm(LLGA)based on the messy Genetic Algorithm(mGA)to optimize the Min-Max fuel controller performance in Gas Turbine Engine(GTE).For this purpose,a GTE fuel controller Simulink model based on the Min-Max selection strategy is firstly built.Then,the objective function that considers both performance indices(response time and fuel consumption)and penalty items(fluctuation,tracking error,overspeed and acceleration/deceleration)is established to quantify the controller performance.Next,the task to optimize the fuel controller is converted to find the optimization gains combination that could minimize the objective function while satisfying constraints and limitations.In order to reduce the optimization time and to avoid trapping in the local optimums,two kinds of building block detection methods including lower fitness value method and bigger fitness value change method are proposed to determine the most important bits which have more contribution on fitness value of the chromosomes.Then the procedures to apply LLGA in controller gains tuning are specified stepwise and the optimization results in runway condition are depicted subsequently.Finally,the comparison is made between the LLGA and the simple GA in GTE controller optimization to confirm the effectiveness of the proposed approach.The results show that the LLGA method can get better solution than simple GA within the same iterations or optimization time.The extension applications of the LLGA method in other flight conditions and the complete flight mission simulation will be carried out in partⅡ.展开更多
In order to clarify the formation mechanism and conditions for akaganeite in long-term exposure, the influence of the former corrosion results on akaganeite formation was investigated by simulated experi- ments in lab...In order to clarify the formation mechanism and conditions for akaganeite in long-term exposure, the influence of the former corrosion results on akaganeite formation was investigated by simulated experi- ments in laboratory. The combination of XRD, FTIR, SEM and EPMA enabled the identification of the rust layer formed on the surface. Accordingly, the nature of the rust layer and the amount of the corrosive species in the rust layer varied with the extension of the exposure. Among them, comparing with the corrosion condition in initial stage, the structure of rust layer after repeated wet-dry cycles was disad- vantage for akaganeite formation. Element CI aggregated at the interface between rust and substrate in the thick part can participate in the formation of akaganeite after the rust layer covered removed. The accumulation effect of salt deposited contributed to akaganeite formation under the condition that salt deposition rate was relatively low.展开更多
A new well test model is developed for the hydraulic fractured well in coalbed by considering the following aspects： methane desorption phenomena, finite conductivity vertical fractures, and asymmetry of the fracture...A new well test model is developed for the hydraulic fractured well in coalbed by considering the following aspects： methane desorption phenomena, finite conductivity vertical fractures, and asymmetry of the fracture about the well. A new parameter is introduced to describe the storage of the fracture, which is named as a combined fracture storage. Another new concept called the fracture asymmetry coefficient is used to define the asymmetry of the fracture about the well. Finite element method （FEM） is used to solve the new mathematical model. The well test type curves and pressure fields are obtained and analyzed. The effects of the combined fracture storage, desorption factor, fracture conductivity, and fracture asymmetry coefficient on the well test type curves are discussed in detail. In order to verify the new model, a set of field well test data is analyzed.展开更多
Porcelain cap and pin insulators are by far the most popular suspension insulators in high voltage(HV) distribution networks all around the world.Inspection and condition monitoring of HV insulators is also very impor...Porcelain cap and pin insulators are by far the most popular suspension insulators in high voltage(HV) distribution networks all around the world.Inspection and condition monitoring of HV insulators is also very important to the utility companies because of the critical and vital role that they play in distribution systems.In terms of safety, practicality and ease of use,remote detection methods are more popular among the line technicians.A new remote condition assessment method based on electromagnetic radiations from porcelain insulators is presented in this paper. In a lab environment,a string of two porcelain insulators is energized by a 45 kV transformer.Electromagnetic radiations due to the partial discharge activities inside the porcelain insulator are captured by passive sensors and antennas. Two cases of defective insulators on a two insulator string are studied here.The first case focuses on the effect of contaminated porcelain shells on radiation signature of partial discharges.A polluted porcelain shell with ESDD level of 0.03 mg/cm^2 was first tested.The second case studies the effect of cracks of an intentionally-cracked porcelain shell. The cracked insulator is also tested on a two insulator string.To compare the partial discharge radiation signature of different faulty insulators,phase resolved graphs were developed.The electromagnetic radiated signature of a polluted insulator and a cracked insulator was calculated and compared using phase resolved graphs.展开更多
The Rana temporaria chensinensis is an amphibian distributing mainly over the north of China. Its skin gland contains a variety of peptides, including antibacterial peptides. One of them, component 1, has been pur...The Rana temporaria chensinensis is an amphibian distributing mainly over the north of China. Its skin gland contains a variety of peptides, including antibacterial peptides. One of them, component 1, has been purified from the dried skin of R.temporaria chensinesis using a five step procedure. Purified component 1 has a molecular weight of 5 700 and its amino acid composition shows that it is devoid of disulfide bridges but rich in histine and glycine residues. Moreover, it has been found that it has a broad spectrum of antibacterial activity for Pseuctomonas aeruginosa, Escherichia coli, Bacillus sublilis, S. faccalis and Proteus vulgaris .展开更多
In this study, Y-and Ce-modified Cr coatings applied by pack cementation method were prepared on the surface of open-cell nickel-based alloy foam. The morphologies and microstructures of Y- and Ce-modified Cr coatings...In this study, Y-and Ce-modified Cr coatings applied by pack cementation method were prepared on the surface of open-cell nickel-based alloy foam. The morphologies and microstructures of Y- and Ce-modified Cr coatings with various Y and Ce contents were investigated in detail. Then, the effects of Y and Ce addition on the mechanical properties of open-cell nickel-based alloy foams were analyzed and compared. Simultaneously, the energy absorption capacity and energy absorption efficiency of the Y- and Ce-modified Cr coated alloy foams were discussed and compared at the room and high temperatures. The results show that Cr coatings containing minor amounts of rare earth element （Y and Ce） are well adhered to the nickel-based foam struts. Especially, the microstructure of the 2 wt% Ce-modified Cr coating is denser and uniform. In addition, the compressive strength and plateau stress of Y- and Ce-modified Cr coated alloy foams firstly increase and then decrease by increasing the Y and Ce contents at room and high temperatures. The energy absorption capacity of Y/Cr and Ce/Cr coated alloy foams increases linearly with the strains increasing. The Ce/Cr coated alloy foams can absorb more energy than Y/Cr coated alloy foams in the plateau and densification regions at room temperature. Compared to those at room temperature, the Y- and Ce-modified Cr coated alloy foams show higher energy absorption efficiency when deforma- tion within 10%-30% at high temperature.展开更多
The objective of this paper is to present a new ideotype of grain legume cultivar and show improvements in breeding from the introduction of the terminal inflorescence （ti） gene in field bean, and the introduction o...The objective of this paper is to present a new ideotype of grain legume cultivar and show improvements in breeding from the introduction of the terminal inflorescence （ti） gene in field bean, and the introduction of the restricted branching （rb） gene in three lupin crops--narrow-leafed lupin, white lupin and yellow lupin. Field trials using control cultivars were conducted at the Research Center for Cultivar Testing in Poland. For each species, different trial periods were selected in which new cultivars with ti/rb genes were registered. A breeding progress was estimated by a comparison of a new cultivar to control--bridge cultivar to the next trial period. Over the past twenty years cultivar improvement using ti/rb genes has proceeded differently in these species. The newest, self-completing legume cultivars have yields comparable to traditional ones and generally are earlier and more uniform when mature. This paper shows that breeding progress in rb yellow lupin is outstanding; in rb narrow-leafed lupin and ti field bean is favorable; and in rb white lupin is moderate.展开更多
The field data of shale fracturing demonstrate that the flowback performance of fracturing fluid is different from that of conventional reservoirs,where the flowback rate of shale fracturing fluid is lower than that o...The field data of shale fracturing demonstrate that the flowback performance of fracturing fluid is different from that of conventional reservoirs,where the flowback rate of shale fracturing fluid is lower than that of conventional reservoirs.At the early stage of flowback,there is no single-phase flow of the liquid phase in shale,but rather a gas-water two-phase flow,such that the single-phase flow model for tight oil and gas reservoirs is not applicable.In this study,pores and microfractures are extracted based on the experimental results of computed tomography(CT)scanning,and a spatial model of microfractures is established.Then,the influence of rough microfracture surfaces on the flow is corrected using the modified cubic law,which was modified by introducing the average deviation of the microfracture height as a roughness factor to consider the influence of microfracture surface roughness.The flow in the fracture network is simulated using the modified cubic law and the lattice Boltzmann method(LBM).The results obtained demonstrate that most of the fracturing fluid is retained in the shale microfractures,which explains the low fracturing fluid flowback rate in shale hydraulic fracturing.展开更多
Albizia coriaria Welw ex.Oliver(hereafter A.coriaria)is a revered medicinal tree whose organs are used by indigenous African societies for managing various ailments.Herein,we assessed the secondary metabolites,total p...Albizia coriaria Welw ex.Oliver(hereafter A.coriaria)is a revered medicinal tree whose organs are used by indigenous African societies for managing various ailments.Herein,we assessed the secondary metabolites,total polyphenolics,free radical scavenging and antimicrobial activities of A.coriaria flowers.The dry powdered sample was extracted serially with ethyl acetate,ethanol and distilled water.Results of classical phytochemical screening showed that saponins,phenols,alkaloids,flavonoids,tannins and terpenes were the dominant phytochemicals.The highest total polyphenolic content(10.37±0.02 mg QE/g DW and 72.09±0.09 mg GAE/g DW)and free radical scavenging potential(IC50=24.23±0.04 mg/mL)were for the ethyl acetate extract.It also had a higher bacteriostatic activity than the ethanolic extract against Pseudomonas aeruginosa,Salmonella typhi,Escherichia coli and Staphylococcus aureus with diameters of inhibition ranging from 7.00±0.00 to 22.00±1.73 mm.The aqueous extract showed no appreciable antibacterial effect on the tested microorganisms.This is the first report which support the use of floral extracts of this species in the management of ailments in African traditional medicine.展开更多
There are numerous reports regarding the antimicrobial effects of herbal extracts on bacteria and fungi. We have prepared water extracts of Wild Leek （A. ampeloprasum var. porrum）, Kurrat （A. ampeloprasum var. kur...There are numerous reports regarding the antimicrobial effects of herbal extracts on bacteria and fungi. We have prepared water extracts of Wild Leek （A. ampeloprasum var. porrum）, Kurrat （A. ampeloprasum var. kurrat） and Elephant Garlic （A. ampeloprasum var. ampeloprasum） by rotary vacuum distillation. As a result, the extraction was carried out in 40 ℃ thus omitting any risk of loss of anti-bacterial activity due to high temperatures reported in prior similar studies [ 1]. The five bacteria Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli, Enterococcus faecalis, and Staphylococcus aureus were tested against the extracts. While some extent of inhibition was observed when the bacteria were cultured in presence of the leek and kurrat extracts, elephant garlic was determined to possess an extreme inhibitory quality against all the aforementioned bacteria, completely inhibiting the growth of the bacteria after 24 hrs of culture in exposure to the extract. We propose that elephant garlic extract could be an effective alternative to chemical antibiotic treatments and disinfectants in hospital and other settings in which infections are common.展开更多
The corrosion resistances of widely used X33CrNiMnN23-8, X50CrMnNiNbN21-9, X53CrMnNiN20-8 and X55CrMnNiN20-8 high-alloyed austenite valves steels in combustion engines have been compared. The comparison was performed ...The corrosion resistances of widely used X33CrNiMnN23-8, X50CrMnNiNbN21-9, X53CrMnNiN20-8 and X55CrMnNiN20-8 high-alloyed austenite valves steels in combustion engines have been compared. The comparison was performed on the basis of results of kinetic corrosion of the test steels in combustion gases from gasoline with 5% ethanol additive （v/v） and the combustion gases from propane-butane. The corrosion test was performed gravimetrically under thermal shock conditions by heating samples of the test steels from room temperature up to 1,173 K in exhaust gases from a combustion engine, and holding them at this temperature for 2 h and then cooling at room temperature for about 25 min. Then the same thermal shock was repeated and after every 10 to 20 such cycles the mass of the specimens was measured. This experiment simulated the working conditions of a highly thermal loaded exhaust valve in a spark ignited engine. The analysis performed shows that the corrosion resistances of X33CrNiMnN23-8 and X50CrMnNiNbN21-9 valve steels in an environment of combustion gases from propane-butane and in gases from gasoline with 5% ethanol additive （v/v） are comparable, whereas the corrosion resistance of X53CrMnNiN20-8 and X55CrMnNiN20-8 valve steels in an environment of combustion gases from propane-butane is slightly worse than in gases from gasoline with 5% ethanol additive （v/v）.展开更多
The article discusses engineering approaches to solving the problem of oil vapours in generators. Due to the design characteristics of each power plant, it is difficult to find a typical solution. Nevertheless, the ar...The article discusses engineering approaches to solving the problem of oil vapours in generators. Due to the design characteristics of each power plant, it is difficult to find a typical solution. Nevertheless, the article suggests ways to reduce the amount of oil mist. For their implementation, a calculation methodology based on the substitution scheme of the hydraulic path of the bearing support unit is created which takes into account the design features of the bearing and the parameters of the environment around the oil bath. The methodology employed is presented. The numerical method of modelling the aerodynamic fields of the entire hydro generator is used to estimate the air flows and pressures in the oil bath zone of the thrust bearing. Additionally, the method made it possible to track suspected oil particles that could get from the thrust-bearing bath into the surrounding area of the generator. Measures are proposed to reduce the level of oil mist through the competent design of the oil vapour removal system from the bearing bath.展开更多
Coal mass consists of matrices and cleats,which exhibits significant difference in mechanical properties,such as uniaxial compressive strength and Young’s modulus.Understanding this difference is critical for a numbe...Coal mass consists of matrices and cleats,which exhibits significant difference in mechanical properties,such as uniaxial compressive strength and Young’s modulus.Understanding this difference is critical for a number of engineering applications,such as assessing the stability of cleated coal seam gas wellbores,underground exca-vation stability in coal seams,and estimating cleat aperture response during gas extraction and surface response to reservoir depletion.The conventional method of measuring coal mechanical properties using strain gauges or displacement transducers is impractical and unreliable as it only captures the value for the installed point.This study explores the use of a two-dimensional Digital Image Correlation(2D-DIC)method to quantify the areal deformation of coal matrix and cleat regions and their contribution to the bulk mechanical properties of coal.Cyclic uniaxial compression tests were performed on coal specimens from the Goonyella Middle Seam,Australia.The results from the DIC technique were initially validated against strain gauge and Advanced Video Exten-someter(AVE)measurements,showing minimal percentage differences:5%with the strain gauge;16.6%with the coal cleat region,12.03%with the coal matrix region,and 9.28%with the coal bulk region compared to AVE.These results demonstrate that DIC is a reliable and accurate method for measuring coal deformation.Comparative analysis of cleat,matrix,and overall coal surface regions revealed distinct variations in Young’s modulus,with ratios of E_(cleat):E_(matrix):E_(overall)=0.24:1.60:1.00.The calculated cleat and matrix moduli are 143.6 MPa and 1785.3 MPa respectively.The contributions of E_(matrix)and E_(cleat)to the overall Young’s modulus(E_(overall))were quantified,revealing that the matrix accounts for 56%(A=0.56)and the cleat for 44%(1-A=0.44)of the overall modulus.The compressibility of the cleat shows six times that of the coal matrix(C_(cleat):C_(matrix):C_(overall)=4.24:0.62:1.00),highlighting the critical role of cleats in coal deformation and stress-induced permeability changes.Furthermore,Poisson’s ratios computed from the DIC for the tested coal samples range from 0.19 to 0.33,showing strong agreement with reported values in the literature.By integrating DIC analysis with traditional mechanical testing,this study offers a robust approach to evaluating full-field deformation mechanisms in fractured materials.These findings advance the understanding of coal’s mechanical properties,which in turn supports more accurate geotechnical modeling,optimizes mining design,and enhances coal seam gas extraction strategies.展开更多
It is well known that groove texture with a careful design can be used to enhance the load‐carrying capacity of oil film under the conditions of hydrodynamic lubrication.In this study,a general parametric model was d...It is well known that groove texture with a careful design can be used to enhance the load‐carrying capacity of oil film under the conditions of hydrodynamic lubrication.In this study,a general parametric model was developed,and agenetic algorithm‐sequential quadratic programming hybrid method was adopted to obtain the global‐optimum profile of the groove texture.The optimized profiles at different rotating speeds are all chevrons.The numerical analysis results verified the effect of the optimization.In addition to the numerical optimization,experiments were conducted to validate the superiority of the optimized results.The experimental results show that the optimized groove texture can efficiently reduce the coefficient of friction(COF)and the temperature rise of the specimen.In particular,the optimized groove textures can achieve stable ultra‐low COF values(COF<0.01)under certain conditions.展开更多
A big yield drop has been observed during the automatic inspection （AO1） after the saw stage. A step by step AOl inspection check and defect review is made to see which step made a big yield drop and which kind of d...A big yield drop has been observed during the automatic inspection （AO1） after the saw stage. A step by step AOl inspection check and defect review is made to see which step made a big yield drop and which kind of defect contributed most to the yield drop. Scanning electron microscope （SEM） and energy dispersive spectrometer （EDS） analysis showed the shape and chemical element of the particle. From the EDS result, particles can be separated into two categories. One was the inorganic related materials, mainly including silicon （Si） element, which came from the saw stage. A design of experiment （DOE） is used to find some reasonable saw relative parameter and optimize it in order to remove the particle from the saw stage. But the quantity of this kind of particle was small. Yield was only improved by less than 5%. Our main effort was to remove another kind of particle which was organic related materials, mainly including carbon （C） and oxygen （O） elernent. This kind of particle was from tape residue. In order to remove the tape residual, one step was added before the saw stage. Almost all of the tape residual was removed. Finally, the final yield was improved by more than 15%.展开更多
The impact ofmagnetism on chemical ordering in face-centered cubic CrCoNi medium entropy alloy is studied by a combination of ab initio simulations,machine learning potentials,and Monte Carlo simulations.Large magneti...The impact ofmagnetism on chemical ordering in face-centered cubic CrCoNi medium entropy alloy is studied by a combination of ab initio simulations,machine learning potentials,and Monte Carlo simulations.Large magnetic energies are revealed for some mixed L1_(2)/L1_(0) type ordered configurations,which are rooted in strong nearest-neighbor magnetic exchange interactions and chemical bonding among the constituent elements.展开更多
基金supported by the National Natural Science Foundation of China(32270564 to P.Y.,82394422 to X.J.L.,82371178 to B.L.)Guangdong Basic and Applied Basic Research(2022A1515011205 and 2023A1515010811 to P.Y.,2021ZT09Y007 and 2018B030337001 to X.J.L.)。
文摘Cytoplasmic accumulation of TDP-43 is a pathological hallmark of amyotrophic lateral sclerosis(ALS)and other neurodegenerative diseases.While current studies have primarily focused on gene regulation mediated by full-length nuclear TDP-43,the potential effects of cytoplasmic TDP-43 fragments remain less explored.Our previous findings demonstrated that primate-specific cleavage of TDP-43 contributes to its cytoplasmic localization,prompting further investigation into its pathological effects.In the cynomolgus monkey brain,we observed that mutant or truncated TDP-43 was transported onto the ribosome organelle.Ribosome-associated transcriptomic analysis revealed dysregulation of apoptosis-and lysosome-related genes,indicating that cytoplasmic TDP-43 induces neurotoxicity by binding to ribosomes and disrupting mRNA expression.These findings provide mechanistic insights into the gain-of-function effects of pathological TDP-43.
基金Manitoba Hydro for funding and supporting this research
文摘An online partial discharge(PD) measurement performed on a high voltage direct current(HVDC) wall bushing successfully identified the presence of internal discharges.The wall bushing is a sulfur hexafluoride gas-insulated bushing,rated for 500 kV dc and terminated on a thyristor-controlled HVDC converter bridge.The measurement of PD within the HVDC station environment is particularly challenging due to the high levels of electromagnetic noise caused by thyristor switching events and external air-corona from the neighboring high-voltage equipment.An additional challenge is the""mixed"voltage stress on the bushing insulation,which has both ac and dc high-voltage components.There are also fast transients during the firing of thyristors in the HVDC conversion process that cause added stress to the insulation.As a result,the analysis and interpretation of PD data for HVDC equipment is more complex;PD pulses may occur in response to the ac,dc,or switching transient voltage stresses.In this paper,an online PD measurement strategy for noise filtering and isolation of PD sources within the bushing are discussed.The PD measurement data is plotted on a phase-resolved diagram where the line supply power cord voltage was used as a reference. The phase-resolved diagram appears to suggest that the fast transients,caused during switching,trigger some PD events.Measurements were also performed with the aid of a modern PD measurement instrument having noise separation capabilities.The findings from the online PD measurements are verified with physical evidence,found after the bushing was removed from service,suggested internal PD had occurred inside the bushing.
文摘PartⅠhas illustrated the procedures to apply the Linkage Learning Genetic Algorithm(LLGA)in Gas Turbine Engine(GTE)controller gains tuning and generated the optimization results for runway conditions from idle to takeoff.However,the total pressure and temperature of the engine inlet vary as the changing of altitude and Mach number,which would lead to the variation in fuel flow supply regulation.As a result,the optimized gains in runway might not be suitable for other flight conditions.In order to maintain the optimal control performance,the GTE controller gains should be adjusted according to the flight conditions.This paper extends the application of the LLGA method to other flight conditions and then simulates a complete flight mission with different gains and weather condition configurations.For this purpose,the control parameters in the Simulink model of the GTE controller are first corrected by the weather condition in altitude.Then,a typical flight mission is defined and divided into different flight segments based on the altitude and Mach number configuration.One representative point is selected from each segment as the datum point for optimization process.After this step,the LLGA method is used to find the best gains combinations for different flight conditions and the differences in optimization effects for different flight conditions are analyzed subsequently.The simulation results show that the optimization effect of the control performance of each flight condition is dependent on the value of(θδ)~(1/2)and the optimal K_(pla)in some flight conditions is approximately equal to p hd times of the Kplavalue in sea level standard condition.Finally,the complete flight mission is simulated with different gains and weather condition configurations.The simulation results show that the engine performance has been greatly improved after optimization by LLGA in the transient state and the high altitude conditions.In other steady states,the optimization effect is not very obvious.
文摘This paper proposes a Linkage Learning Genetic Algorithm(LLGA)based on the messy Genetic Algorithm(mGA)to optimize the Min-Max fuel controller performance in Gas Turbine Engine(GTE).For this purpose,a GTE fuel controller Simulink model based on the Min-Max selection strategy is firstly built.Then,the objective function that considers both performance indices(response time and fuel consumption)and penalty items(fluctuation,tracking error,overspeed and acceleration/deceleration)is established to quantify the controller performance.Next,the task to optimize the fuel controller is converted to find the optimization gains combination that could minimize the objective function while satisfying constraints and limitations.In order to reduce the optimization time and to avoid trapping in the local optimums,two kinds of building block detection methods including lower fitness value method and bigger fitness value change method are proposed to determine the most important bits which have more contribution on fitness value of the chromosomes.Then the procedures to apply LLGA in controller gains tuning are specified stepwise and the optimization results in runway condition are depicted subsequently.Finally,the comparison is made between the LLGA and the simple GA in GTE controller optimization to confirm the effectiveness of the proposed approach.The results show that the LLGA method can get better solution than simple GA within the same iterations or optimization time.The extension applications of the LLGA method in other flight conditions and the complete flight mission simulation will be carried out in partⅡ.
基金financially supported by the National Natural Science Foundation of China under the contract Nos.51301182 and 51671198the National Basic Research Program of China and Ministry of Science and Technology China under the contract No.2014CB643303
文摘In order to clarify the formation mechanism and conditions for akaganeite in long-term exposure, the influence of the former corrosion results on akaganeite formation was investigated by simulated experi- ments in laboratory. The combination of XRD, FTIR, SEM and EPMA enabled the identification of the rust layer formed on the surface. Accordingly, the nature of the rust layer and the amount of the corrosive species in the rust layer varied with the extension of the exposure. Among them, comparing with the corrosion condition in initial stage, the structure of rust layer after repeated wet-dry cycles was disad- vantage for akaganeite formation. Element CI aggregated at the interface between rust and substrate in the thick part can participate in the formation of akaganeite after the rust layer covered removed. The accumulation effect of salt deposited contributed to akaganeite formation under the condition that salt deposition rate was relatively low.
基金Project supported by the National Science and Technology Major Project of China(No.2011ZX05038003)the Science and Technology Project of PetroChina Company Limited(No.2010E-2205)
文摘A new well test model is developed for the hydraulic fractured well in coalbed by considering the following aspects： methane desorption phenomena, finite conductivity vertical fractures, and asymmetry of the fracture about the well. A new parameter is introduced to describe the storage of the fracture, which is named as a combined fracture storage. Another new concept called the fracture asymmetry coefficient is used to define the asymmetry of the fracture about the well. Finite element method （FEM） is used to solve the new mathematical model. The well test type curves and pressure fields are obtained and analyzed. The effects of the combined fracture storage, desorption factor, fracture conductivity, and fracture asymmetry coefficient on the well test type curves are discussed in detail. In order to verify the new model, a set of field well test data is analyzed.
文摘Porcelain cap and pin insulators are by far the most popular suspension insulators in high voltage(HV) distribution networks all around the world.Inspection and condition monitoring of HV insulators is also very important to the utility companies because of the critical and vital role that they play in distribution systems.In terms of safety, practicality and ease of use,remote detection methods are more popular among the line technicians.A new remote condition assessment method based on electromagnetic radiations from porcelain insulators is presented in this paper. In a lab environment,a string of two porcelain insulators is energized by a 45 kV transformer.Electromagnetic radiations due to the partial discharge activities inside the porcelain insulator are captured by passive sensors and antennas. Two cases of defective insulators on a two insulator string are studied here.The first case focuses on the effect of contaminated porcelain shells on radiation signature of partial discharges.A polluted porcelain shell with ESDD level of 0.03 mg/cm^2 was first tested.The second case studies the effect of cracks of an intentionally-cracked porcelain shell. The cracked insulator is also tested on a two insulator string.To compare the partial discharge radiation signature of different faulty insulators,phase resolved graphs were developed.The electromagnetic radiated signature of a polluted insulator and a cracked insulator was calculated and compared using phase resolved graphs.
文摘The Rana temporaria chensinensis is an amphibian distributing mainly over the north of China. Its skin gland contains a variety of peptides, including antibacterial peptides. One of them, component 1, has been purified from the dried skin of R.temporaria chensinesis using a five step procedure. Purified component 1 has a molecular weight of 5 700 and its amino acid composition shows that it is devoid of disulfide bridges but rich in histine and glycine residues. Moreover, it has been found that it has a broad spectrum of antibacterial activity for Pseuctomonas aeruginosa, Escherichia coli, Bacillus sublilis, S. faccalis and Proteus vulgaris .
基金financially supported by the National Natural Science Foundation of China (Nos.51501133 and 51405358)the China Automobile Industry Innovation and Development Joint Fund (No.U1564202)+1 种基金the Natural Science Foundation of Hubei Province (No.2016CFC773)the State Key Laboratory of Advanced Welding and Joining,Harbin Institute of Technology (No.AWJ-M16-11)
文摘In this study, Y-and Ce-modified Cr coatings applied by pack cementation method were prepared on the surface of open-cell nickel-based alloy foam. The morphologies and microstructures of Y- and Ce-modified Cr coatings with various Y and Ce contents were investigated in detail. Then, the effects of Y and Ce addition on the mechanical properties of open-cell nickel-based alloy foams were analyzed and compared. Simultaneously, the energy absorption capacity and energy absorption efficiency of the Y- and Ce-modified Cr coated alloy foams were discussed and compared at the room and high temperatures. The results show that Cr coatings containing minor amounts of rare earth element （Y and Ce） are well adhered to the nickel-based foam struts. Especially, the microstructure of the 2 wt% Ce-modified Cr coating is denser and uniform. In addition, the compressive strength and plateau stress of Y- and Ce-modified Cr coated alloy foams firstly increase and then decrease by increasing the Y and Ce contents at room and high temperatures. The energy absorption capacity of Y/Cr and Ce/Cr coated alloy foams increases linearly with the strains increasing. The Ce/Cr coated alloy foams can absorb more energy than Y/Cr coated alloy foams in the plateau and densification regions at room temperature. Compared to those at room temperature, the Y- and Ce-modified Cr coated alloy foams show higher energy absorption efficiency when deforma- tion within 10%-30% at high temperature.
文摘The objective of this paper is to present a new ideotype of grain legume cultivar and show improvements in breeding from the introduction of the terminal inflorescence （ti） gene in field bean, and the introduction of the restricted branching （rb） gene in three lupin crops--narrow-leafed lupin, white lupin and yellow lupin. Field trials using control cultivars were conducted at the Research Center for Cultivar Testing in Poland. For each species, different trial periods were selected in which new cultivars with ti/rb genes were registered. A breeding progress was estimated by a comparison of a new cultivar to control--bridge cultivar to the next trial period. Over the past twenty years cultivar improvement using ti/rb genes has proceeded differently in these species. The newest, self-completing legume cultivars have yields comparable to traditional ones and generally are earlier and more uniform when mature. This paper shows that breeding progress in rb yellow lupin is outstanding; in rb narrow-leafed lupin and ti field bean is favorable; and in rb white lupin is moderate.
基金supported by the National Natural Science Foundation of China(Grant No.52022087).
文摘The field data of shale fracturing demonstrate that the flowback performance of fracturing fluid is different from that of conventional reservoirs,where the flowback rate of shale fracturing fluid is lower than that of conventional reservoirs.At the early stage of flowback,there is no single-phase flow of the liquid phase in shale,but rather a gas-water two-phase flow,such that the single-phase flow model for tight oil and gas reservoirs is not applicable.In this study,pores and microfractures are extracted based on the experimental results of computed tomography(CT)scanning,and a spatial model of microfractures is established.Then,the influence of rough microfracture surfaces on the flow is corrected using the modified cubic law,which was modified by introducing the average deviation of the microfracture height as a roughness factor to consider the influence of microfracture surface roughness.The flow in the fracture network is simulated using the modified cubic law and the lattice Boltzmann method(LBM).The results obtained demonstrate that most of the fracturing fluid is retained in the shale microfractures,which explains the low fracturing fluid flowback rate in shale hydraulic fracturing.
文摘Albizia coriaria Welw ex.Oliver(hereafter A.coriaria)is a revered medicinal tree whose organs are used by indigenous African societies for managing various ailments.Herein,we assessed the secondary metabolites,total polyphenolics,free radical scavenging and antimicrobial activities of A.coriaria flowers.The dry powdered sample was extracted serially with ethyl acetate,ethanol and distilled water.Results of classical phytochemical screening showed that saponins,phenols,alkaloids,flavonoids,tannins and terpenes were the dominant phytochemicals.The highest total polyphenolic content(10.37±0.02 mg QE/g DW and 72.09±0.09 mg GAE/g DW)and free radical scavenging potential(IC50=24.23±0.04 mg/mL)were for the ethyl acetate extract.It also had a higher bacteriostatic activity than the ethanolic extract against Pseudomonas aeruginosa,Salmonella typhi,Escherichia coli and Staphylococcus aureus with diameters of inhibition ranging from 7.00±0.00 to 22.00±1.73 mm.The aqueous extract showed no appreciable antibacterial effect on the tested microorganisms.This is the first report which support the use of floral extracts of this species in the management of ailments in African traditional medicine.
文摘There are numerous reports regarding the antimicrobial effects of herbal extracts on bacteria and fungi. We have prepared water extracts of Wild Leek （A. ampeloprasum var. porrum）, Kurrat （A. ampeloprasum var. kurrat） and Elephant Garlic （A. ampeloprasum var. ampeloprasum） by rotary vacuum distillation. As a result, the extraction was carried out in 40 ℃ thus omitting any risk of loss of anti-bacterial activity due to high temperatures reported in prior similar studies [ 1]. The five bacteria Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli, Enterococcus faecalis, and Staphylococcus aureus were tested against the extracts. While some extent of inhibition was observed when the bacteria were cultured in presence of the leek and kurrat extracts, elephant garlic was determined to possess an extreme inhibitory quality against all the aforementioned bacteria, completely inhibiting the growth of the bacteria after 24 hrs of culture in exposure to the extract. We propose that elephant garlic extract could be an effective alternative to chemical antibiotic treatments and disinfectants in hospital and other settings in which infections are common.
文摘The corrosion resistances of widely used X33CrNiMnN23-8, X50CrMnNiNbN21-9, X53CrMnNiN20-8 and X55CrMnNiN20-8 high-alloyed austenite valves steels in combustion engines have been compared. The comparison was performed on the basis of results of kinetic corrosion of the test steels in combustion gases from gasoline with 5% ethanol additive （v/v） and the combustion gases from propane-butane. The corrosion test was performed gravimetrically under thermal shock conditions by heating samples of the test steels from room temperature up to 1,173 K in exhaust gases from a combustion engine, and holding them at this temperature for 2 h and then cooling at room temperature for about 25 min. Then the same thermal shock was repeated and after every 10 to 20 such cycles the mass of the specimens was measured. This experiment simulated the working conditions of a highly thermal loaded exhaust valve in a spark ignited engine. The analysis performed shows that the corrosion resistances of X33CrNiMnN23-8 and X50CrMnNiNbN21-9 valve steels in an environment of combustion gases from propane-butane and in gases from gasoline with 5% ethanol additive （v/v） are comparable, whereas the corrosion resistance of X53CrMnNiN20-8 and X55CrMnNiN20-8 valve steels in an environment of combustion gases from propane-butane is slightly worse than in gases from gasoline with 5% ethanol additive （v/v）.
文摘The article discusses engineering approaches to solving the problem of oil vapours in generators. Due to the design characteristics of each power plant, it is difficult to find a typical solution. Nevertheless, the article suggests ways to reduce the amount of oil mist. For their implementation, a calculation methodology based on the substitution scheme of the hydraulic path of the bearing support unit is created which takes into account the design features of the bearing and the parameters of the environment around the oil bath. The methodology employed is presented. The numerical method of modelling the aerodynamic fields of the entire hydro generator is used to estimate the air flows and pressures in the oil bath zone of the thrust bearing. Additionally, the method made it possible to track suspected oil particles that could get from the thrust-bearing bath into the surrounding area of the generator. Measures are proposed to reduce the level of oil mist through the competent design of the oil vapour removal system from the bearing bath.
文摘Coal mass consists of matrices and cleats,which exhibits significant difference in mechanical properties,such as uniaxial compressive strength and Young’s modulus.Understanding this difference is critical for a number of engineering applications,such as assessing the stability of cleated coal seam gas wellbores,underground exca-vation stability in coal seams,and estimating cleat aperture response during gas extraction and surface response to reservoir depletion.The conventional method of measuring coal mechanical properties using strain gauges or displacement transducers is impractical and unreliable as it only captures the value for the installed point.This study explores the use of a two-dimensional Digital Image Correlation(2D-DIC)method to quantify the areal deformation of coal matrix and cleat regions and their contribution to the bulk mechanical properties of coal.Cyclic uniaxial compression tests were performed on coal specimens from the Goonyella Middle Seam,Australia.The results from the DIC technique were initially validated against strain gauge and Advanced Video Exten-someter(AVE)measurements,showing minimal percentage differences:5%with the strain gauge;16.6%with the coal cleat region,12.03%with the coal matrix region,and 9.28%with the coal bulk region compared to AVE.These results demonstrate that DIC is a reliable and accurate method for measuring coal deformation.Comparative analysis of cleat,matrix,and overall coal surface regions revealed distinct variations in Young’s modulus,with ratios of E_(cleat):E_(matrix):E_(overall)=0.24:1.60:1.00.The calculated cleat and matrix moduli are 143.6 MPa and 1785.3 MPa respectively.The contributions of E_(matrix)and E_(cleat)to the overall Young’s modulus(E_(overall))were quantified,revealing that the matrix accounts for 56%(A=0.56)and the cleat for 44%(1-A=0.44)of the overall modulus.The compressibility of the cleat shows six times that of the coal matrix(C_(cleat):C_(matrix):C_(overall)=4.24:0.62:1.00),highlighting the critical role of cleats in coal deformation and stress-induced permeability changes.Furthermore,Poisson’s ratios computed from the DIC for the tested coal samples range from 0.19 to 0.33,showing strong agreement with reported values in the literature.By integrating DIC analysis with traditional mechanical testing,this study offers a robust approach to evaluating full-field deformation mechanisms in fractured materials.These findings advance the understanding of coal’s mechanical properties,which in turn supports more accurate geotechnical modeling,optimizes mining design,and enhances coal seam gas extraction strategies.
文摘It is well known that groove texture with a careful design can be used to enhance the load‐carrying capacity of oil film under the conditions of hydrodynamic lubrication.In this study,a general parametric model was developed,and agenetic algorithm‐sequential quadratic programming hybrid method was adopted to obtain the global‐optimum profile of the groove texture.The optimized profiles at different rotating speeds are all chevrons.The numerical analysis results verified the effect of the optimization.In addition to the numerical optimization,experiments were conducted to validate the superiority of the optimized results.The experimental results show that the optimized groove texture can efficiently reduce the coefficient of friction(COF)and the temperature rise of the specimen.In particular,the optimized groove textures can achieve stable ultra‐low COF values(COF<0.01)under certain conditions.
文摘A big yield drop has been observed during the automatic inspection （AO1） after the saw stage. A step by step AOl inspection check and defect review is made to see which step made a big yield drop and which kind of defect contributed most to the yield drop. Scanning electron microscope （SEM） and energy dispersive spectrometer （EDS） analysis showed the shape and chemical element of the particle. From the EDS result, particles can be separated into two categories. One was the inorganic related materials, mainly including silicon （Si） element, which came from the saw stage. A design of experiment （DOE） is used to find some reasonable saw relative parameter and optimize it in order to remove the particle from the saw stage. But the quantity of this kind of particle was small. Yield was only improved by less than 5%. Our main effort was to remove another kind of particle which was organic related materials, mainly including carbon （C） and oxygen （O） elernent. This kind of particle was from tape residue. In order to remove the tape residual, one step was added before the saw stage. Almost all of the tape residual was removed. Finally, the final yield was improved by more than 15%.
文摘The impact ofmagnetism on chemical ordering in face-centered cubic CrCoNi medium entropy alloy is studied by a combination of ab initio simulations,machine learning potentials,and Monte Carlo simulations.Large magnetic energies are revealed for some mixed L1_(2)/L1_(0) type ordered configurations,which are rooted in strong nearest-neighbor magnetic exchange interactions and chemical bonding among the constituent elements.
