The binding energy and effective mass of a polaron confined in a GaAs film deposited on an AlGal-xAs substrate are investigated, for different film thickness values and aluminum concentra- tions and within the framewo...The binding energy and effective mass of a polaron confined in a GaAs film deposited on an AlGal-xAs substrate are investigated, for different film thickness values and aluminum concentra- tions and within the framework of the fractional-dimensional space approach. Using this scheme, we propose a new method to define the effective length of the quantum confinement. The limita- tions of the definition of the original effective well width are discussed, and the binding energy and effective mass of a polaron confined in a GaAs film are obtained. The fl-actional-dimensional theo- retical results are shown to be in good agreement with previous, more detailed calculations based on second-order perturbation theory.展开更多
The design of columns relies heavily on the basis of Leonhard Euler’s Theory of Elastic Buckling.However,to increase the accuracy in determining the maximum critical load a column can withstand before buckling,a cons...The design of columns relies heavily on the basis of Leonhard Euler’s Theory of Elastic Buckling.However,to increase the accuracy in determining the maximum critical load a column can withstand before buckling,a constant was introduced.This dimensionless coefficient is K,also known as the effective-length factor.This constant is often found in building design codes and varies in value depending on the type of column support that is applied.This paper presents experimental and analytical studies on the determination of the effective-length factor in the buckling stability of columns with partially-fixed support conditions.To this end,the accurate K value of the columns tested by the Instron Testing Machine(ITM)at California State University,Northridge’s(CSUN’s)Mechanics Laboratory is determined.The ITM is used in studying the buckling of columns where the supports are neither pinned nor fixed,and the material cross-section rather rests upon the machine while loading is applied axially.Several column specimens were tested and the experimental data were analyzed in order to estimation of the accurate effective-length factor.The calculations from the tested results as well as the conducted probabilistic analysis shed light on how a fragility curve may aid in predicting the effective-length value of future tests.展开更多
A new method is proposed for the effective roughness length (ERL) in heterogeneous terrain based on the principle of equalisation of momentum or heat fluxes calculated by the drag coefficient parameterization scheme u...A new method is proposed for the effective roughness length (ERL) in heterogeneous terrain based on the principle of equalisation of momentum or heat fluxes calculated by the drag coefficient parameterization scheme used in the ECMWF numerical model. Compared with the area-weighted logarithmically averaged ERL (drag coefficient), the newly calculated ERL (drag coefficient) is about 40% (16%) larger with a roughness step of 2.3. These differences reach their maximum values when the ratio of smooth to rough surface is 60% to 40%. Since the determination by this method is not sensitive to the atmospheric stratification, it is suitable for use in climate models.展开更多
For the purpose of improving the accuracy and effectiveness of acid fracturing design for carbonate reservoirs with developed natural fractures,an acidizingfluidflow and reaction model taking the multiple leak-off effec...For the purpose of improving the accuracy and effectiveness of acid fracturing design for carbonate reservoirs with developed natural fractures,an acidizingfluidflow and reaction model taking the multiple leak-off effect of natural fracture,wormhole and matrix into account was established according to the liquid phase reaction equilibrium principle and the local reaction equilibrium principle after the dynamic change of fracture geometry in the process of fracture created by prepadfluid was simulated in the classical pseudo-three dimensional mathematical model of fracture propagation.Then,the acid fracturing stimulation of a case well on site was taken as an example.The newly developed model was used to simulate thefiltration process of acidizingfluid in fractures and the dynamic etching morphology of acidic rocks during the acidizingfluid injection of prepad acid fracturing.The effective length of etched fractures was determined by analyzing the concentration change of acidizingfluid along the direction of hydraulic fracture length and the threshold concentration of residual acidizingfluid comprehensively,and then it was compared with the interpretation result of pressure buildup test.And the following research results were obtained.First,in the process of acid fracturing in fracturedeporous reservoirs,the acidizingfluidfiltration velocity along the direction of fracture length is not constant and thefiltration velocity curvefluctuates in a serrated shape.And the acidizingfluidfiltration velocity where etched wormholes meet natural fractures is commonly higher than that in matrix.Second,acidizingfluid is lost seriously and the effective distance of acidizingfluid gets short significantly during the acid fracturing of fracturedeporous reservoirs.Third,acid fracturing in the verification well is remarkable in blockage removing and stimulation,and its well test interpretation results are consistent with the simulation interpretation results provided by the newly developed mathematical model.It is indicated that this newly developed model is reliable.In conclusion,the mathematical model of prepad acid fracturing which considers multiple leak-off effect is more suitable for acid fracturing simulation of fracturedeporous reservoirs.展开更多
This article describes the effective channel length degradation under hot carrier stressing. The extraction is based on the IDs-Vcs characteristics by maximum transconductance （maximum slope of IDs ＆ VGS） in the li...This article describes the effective channel length degradation under hot carrier stressing. The extraction is based on the IDs-Vcs characteristics by maximum transconductance （maximum slope of IDs ＆ VGS） in the linear region. The transconductance characteristics are determine for the several devices of difference drawn channel length. The effective channel length of submicron LDD （Lightly Doped Drain） NMOSFETs （Metal Oxide Semiconductor Field Effect Transistor） under hot carrier stressing was measured at the stress time varying from zero to 10,000 seconds. It is shown that the effective channel length was increased with time. This is caused by charges trapping in the oxide during stress. The increased of effective channel length （△Leff） is seem to be increased sharply as the gate channel length is decrease.展开更多
The calculation equation of large diameter bored pile＇s effective length is connected with its distribution of pile shaft resistance. Thus, there is a great difference between the calculation results under the differ...The calculation equation of large diameter bored pile＇s effective length is connected with its distribution of pile shaft resistance. Thus, there is a great difference between the calculation results under the different distributions of pile shaft resistance. Primarily, this paper summarizes the conceptualized mode of pile shaft resistance under the circum- stance that the soil surrounding the piles presents different layer distributions. Secondly, based on Mindlin＇s displacement solution and in consideration of the effect of pile diam- eter, the calculation equation is optimized with the assumption that the pile shaft resis- tance has a parabolic distribution. The influencing factors are analyzed according to the calculation result of effective pile length. Finally, combined with an engineering example, the calculation equation deduced in this paper is analyzed and verified. The result shows that both the Poisson ratio of soil and pile diameter have impacted the effective pile length. Compared with the Poisson ratio of soil, the effect of pile diameter is more significant. If the pile diameter remains the same, the effect of the Poisson ratio of soil to the effective pile length decreases as the ratio of pile elastic modulus and soil share modulus increases. If the Poisson ratio of soil remains the same, the effect of the pile diameter to the effective pile length increases as the ratio of pile elastic modulus and soil share modulus increases. Thus the optimized calculation result of pile effective length under the consideration of pile diameter effect is more close to the actual situation of engineering and reasonably practicable.展开更多
The present work is concerned with a two-dimensional(2D)Stokes flow through a channel bounded by two parallel solid walls.The distance between the walls may be arbitrary,and the surface of one of the walls can be arbi...The present work is concerned with a two-dimensional(2D)Stokes flow through a channel bounded by two parallel solid walls.The distance between the walls may be arbitrary,and the surface of one of the walls can be arbitrarily rough.The main objective of this work consists in homogenizing the heterogeneous interface between the rough wall and fluid so as to obtain an equivalent smooth slippery fluid/solid interface characterized by an effective slip length.To solve the corresponding problem,two efficient numerical approaches are elaborated on the basis of the method of fundamental solution(MFS)and the boundary element methods(BEMs).They are applied to different cases where the fluid/solid interface is periodically or randomly rough.The results obtained by the proposed two methods are compared with those given by the finite element method and some relevant ones reported in the literature.This comparison shows that the two proposed methods are particularly efficient and accurate.展开更多
Based on the generalized uncertainty principle with maximum momentum arid minimal length, we discuss the equation of state of ideal ultra-relativistic Fermi gases at zero temperature. Maximum momentum avoids the probl...Based on the generalized uncertainty principle with maximum momentum arid minimal length, we discuss the equation of state of ideal ultra-relativistic Fermi gases at zero temperature. Maximum momentum avoids the problem that the Fermi degenerate pressure blows up since the increase of the Fermi energy is not limited. Applying this equation of state to the Tolman-Oppenheimer Volkoff （TOV） equation, the quantum gravitational effects on the cores of compact stars are discussed. In the center of compact stars, we obtain the singularity-free solution of the metric component, gtt ～-（1 ＋ 0.2185×r^2）. By numerically solving the TOV equation, we find that quantum gravity plays an important role in the region r～10^4α0（△x）min. Current observed masses of neutron stars indicate that the dimensionless parameter α0 cannot exceed 10^19.展开更多
The effect of day length and temperature on the pollen fertility of five photoperiod-sensitive genic male-sterile japonica rice lines (PGMSR) and three temperature-sensitive genic malesterile indica rice lines (TGMSR)...The effect of day length and temperature on the pollen fertility of five photoperiod-sensitive genic male-sterile japonica rice lines (PGMSR) and three temperature-sensitive genic malesterile indica rice lines (TGMSR) were investigated in phytotron. The light source used for illumination was xenon lamp, and the light intensity which plant accepted on the leaf surface was 300—350μmol photons ms. The results indicated that pollens of PGMSR 7001S and E47S aborted completely whereas a little part of 31116S pollens appeared normal under long day photoperiod (LD,25℃,15h) (Table 1). High temperature (HT, 30℃, 12h) and lower temperature (LT,展开更多
In this work,the results of an experimental study of the impulse characteristic of practical ground electrodes consisting of horizontal conductors of various lengths and full-scale tower footings were reported.These e...In this work,the results of an experimental study of the impulse characteristic of practical ground electrodes consisting of horizontal conductors of various lengths and full-scale tower footings were reported.These electrodes were installed at an outdoor test site having nonuniform soil,with equipment facilities for generating low-and high-magnitude impulse currents.The tests on the horizontal electrode were used to determine the effective length,the voltage and current distribution along the electrode length and the effect of the injection point along the electrode.The tests on the tower footings were used to determine impulse resistance and demonstrate its non-linear variation with current magnitude.Computer simulations of the test electrodes using the electromagnetic field method showed good agreement with the measured result.展开更多
The forbidden pitch ＂dip＂ in the critical dimension （CD） through the pitch curve is a well-known optical proximity effect. The CD and CD process window near the ＂dip＂,usually found near a pitch range of 1.1 to 1...The forbidden pitch ＂dip＂ in the critical dimension （CD） through the pitch curve is a well-known optical proximity effect. The CD and CD process window near the ＂dip＂,usually found near a pitch range of 1.1 to 1.4 wavelength/ NA （numerical aperture）,is smaller when compared with other pitches. This is caused by inadequate imaging contrast for an unequal line and space grating. Although this effect is relatively well-known, its relationship with typical process condition parameters,such as the effective image blur caused by the photo-acid diffusion during the post exposure bake or the aberration in the imaging lens, has not been systematically studied. In this paper, we will examine the correlation between the image blur and the effect on the CD, including the decrease in the CD value （the depth of the ＂dip＂） and the CD process window. We find that both the decrease in the CD value and the focus latitude near the forbidden pitch correlate very well with the effective Gaussian image blur. Longer effective diffusion length correlates well with a smaller process window and a deeper CD ＂dip＂. We conclude that the dip depth is very sensitive to the change in image contrast.展开更多
By means of the functionality distribution deduced and weight averaged functionality a and molecular size vb2, the sol-gel distribution equations of HTPB(Hydroxyl terminated polybutadiene) + TDI (Toluene-2, 4-diisocya...By means of the functionality distribution deduced and weight averaged functionality a and molecular size vb2, the sol-gel distribution equations of HTPB(Hydroxyl terminated polybutadiene) + TDI (Toluene-2, 4-diisocyanate) expressed by the model of Aai-B2 type polycondensation were solved and the elastic modulus were calculated. The experimental results of HTPB+TDI curing process indicate that a, vb2 and functionality distribution function are available basically.展开更多
The main reaction products were investigated by analysis of microstructure of alkali-activated ground granulated blast furnace slag （GGBFS） paste. An experimental research was performed on bond performance of alkali...The main reaction products were investigated by analysis of microstructure of alkali-activated ground granulated blast furnace slag （GGBFS） paste. An experimental research was performed on bond performance of alkali-activated GGBFS paste as a construction adhesive after exposure to 20-500℃. Through XRD analysis, a few calcium silicate hydrate, hydrotalcite and tetracalcium aluminate hydrate were determined as end products, and they were filled and packed each other at room temperature. In addition, akermanite dramatically increased at 800 ~C and above. The two key parameters, the ultimate load Pu.T and effective bond length Le, were determined using test data of carbon fiber-reinforced polymer （CFRP）-to-concrete bonded joints at elevated temperature. The experimental results indicate that the ultimate load Pu.T remains relatively stable initially and then decreases with increasing temperature. The effective bond length Le increases with increasing temperature except at 300℃. The proposed temperature-dependent effective bond length formula is shown to closely represent the test data.展开更多
By establishing the Markov model for a long-range correlated time series （LRCS） and analysing its evolutionary characteristics, this paper defines a physical effective correlation length （ECL） T, which reflects th...By establishing the Markov model for a long-range correlated time series （LRCS） and analysing its evolutionary characteristics, this paper defines a physical effective correlation length （ECL） T, which reflects the predictability of the LRCS. It also finds that the ECL has a better power law relation with the long-range correlated exponent γ of the LRCS： T = Kexp（-γ/0.3） ＋ Y, （0 〈 γ〈 1） the predictability of the LRCS decays exponentially with the increase of γ It is then applied to a daily maximum temperature series （DMTS） recorded at 740 stations in China between the years 1960-2005 and calculates the ECL of the DMTS. The results show the remarkable regional distributive feature that the ECL is about 10-14 days in west, northwest and northern China, and about 5-10 days in east, southeast and southern China. Namely, the predictability of the DMTS is higher in central-west China than in east and southeast China. In addition, the ECL is reduced by 1-8 days in most areas of China after subtracting the seasonal oscillation signal of the DMTS from its original DMTS; however, it is only slightly altered when the decadal linear trend is removed from the original DMTS. Therefore, it is shown that seasonal oscillation is a significant component of daily maximum temperature evolution and may provide a basis for predicting daily maximum temperatures. Seasonal oscillation is also significant for guiding general weather predictions, as well as seasonal weather predictions.展开更多
Experimental and theoretical researches on nanostructured exchange coupled magnets have been carried out since about 1988. Here, we review the structure and magnetic properties of the anisotropic nanocomposite soft/ha...Experimental and theoretical researches on nanostructured exchange coupled magnets have been carried out since about 1988. Here, we review the structure and magnetic properties of the anisotropic nanocomposite soft/hard multilayer magnets including some new results and phenomena from an experimental point of view. According to the different component of the oriented hard phase in the nanocomposite soft/hard multilayer magnets, three types of magnets will be discussed：1） anisotropic Nd2Fe（14）B based nanocomposite multilayer magnets, 2） anisotropic SmCo5 based nanocomposite multilayer magnets, and 3） anisotropic rare-earth free based nanocomposite multilayer magnets. For each of them, the formation of the oriented hard phase, exchange coupling, coercivity mechanism, and magnetic properties of the corresponding anisotropic nanocomposite multilayer magnets are briefly reviewed, and then the prospect of realization of bulk magnets on new results of anisotropic nanocomposite multilayer magnets will be carried out.展开更多
Removal of the length ef fect in otolith shape analysis for stock identification using length scaling is an important issue; however, few studies have attempted to investigate the ef fectiveness or weakness of this me...Removal of the length ef fect in otolith shape analysis for stock identification using length scaling is an important issue; however, few studies have attempted to investigate the ef fectiveness or weakness of this methodology in application. The aim of this study was to evaluate whether commonly used size scaling methods and normalized elliptic Fourier descriptors(NEFDs) could ef fectively remove the size ef fect of fish in stock discrimination. To achieve this goal, length groups from two known geographical stocks of yellow croaker, L arimichthys polyactis, along the Chinese coast(five groups from the Changjiang River estuary of the East China Sea and three groups from the Bohai Sea) were subjected to otolith shape analysis. The results indicated that the variation of otolith shape caused by intra-stock fish length might exceed that due to inter-stock geographical separation, even when otolith shape variables are standardized with length scaling methods. This variation could easily result in misleading stock discrimination through otolith shape analysis. Therefore, conclusions about fish stock structure should be carefully drawn from otolith shape analysis because the observed discrimination may primarily be due to length ef fects, rather than dif ferences among stocks. The application of multiple methods, such as otoliths shape analysis combined with elemental fingering, tagging or genetic analysis, is recommended for sock identification.展开更多
To solve the difficulty of designing digital impacting filter in the receiver of random-polar modulated Extended Binary Phase Shift Keying with Continuous Phase (CP-EBPSK), a design method based on Quantum-behaved Par...To solve the difficulty of designing digital impacting filter in the receiver of random-polar modulated Extended Binary Phase Shift Keying with Continuous Phase (CP-EBPSK), a design method based on Quantum-behaved Particle Swarm Optimization (QPSO) algorithm is proposed. Firstly, QPSO is introduced elaborately, and the basic flow of QPSO is also given. Then, the demodulation principle of digital impacting filter in the communication system of CP-EBPSK with random-polar is demonstrated, and QPSO is utilized to design the digital impacting filter, which also takes the effect of finite word length into consideration when implemented by hardware. Finally, the proposed method is simulated. Simulation results show that the digital impacting filter designed by new method can derive satisfied demodulation performance.展开更多
Airway smooth muscle(ASM)has developed a mechanical adaption mechanism by which it transduces force and responds to environmental forces,which is essential for periodic breathing.Cytoskeletal reorganization has been i...Airway smooth muscle(ASM)has developed a mechanical adaption mechanism by which it transduces force and responds to environmental forces,which is essential for periodic breathing.Cytoskeletal reorganization has been implicated in this process,but the regulatory mechanism remains to be determined.We here observe that ASM abundantly expresses cytoskeleton regulators Limk1 and Limk2,and their expression levels are further upregulated in chronic obstructive pulmonary disease(COPD)animals.By establishing mouse lines with deletions of Limk1 or Limk2,we analyse the length-sensitive contraction,F/Gactin dynamics,and F-actin pool of mutant ASM cells.As LIMK1 phosphorylation does not respond to the contractile stimulation,LIMK1-deficient ASM develops normal maximal force,while LIMK2 or LIMK1/LIMK2 deficient ASMs show approximately 30%inhibition.LIMK2 deletion causes a significant decrease in cofilin phosphorylation along with a reduced F/G-actin ratio.As LIMK2 functions independently of cross-bridge movement,this observation indicates that LIMK2 is necessary for F-actin dynamics and hence force transduction.Moreover,LIMK2-deficient ASMs display abolishes stretching-induced suppression of 5-hydroxytryptamine(5-HT)but not acetylcholine-evoks force,which is due to the differential contraction mechanisms adopted by the agonists.We propose that LIMK2-mediated cofilin phosphorylation is required for membrane cytoskeleton reorganization that is necessary for ASM mechanical adaption including the 5-HT-evoked length-sensitive effect.展开更多
High strength threaded fasteners are widely used in the aircraft industry, and service experience shows that for structures where shear loading of the joints is significant, like skin splices, fuselage joints or spar ...High strength threaded fasteners are widely used in the aircraft industry, and service experience shows that for structures where shear loading of the joints is significant, like skin splices, fuselage joints or spar caps-web attachments, more cracks are initiated and grow from the edges of the fastener holes than from features like fillets radii and corners or from large access holes. The main causes of this cracking are the stress concentrations introduced by the fastener holes and by the threaded fasteners themselves, with the most common damage site being at the edge of the fastener holes. Intuitively, it is easy to visualize that after the crack initiation, during the growth stages, some of the load transferred initially by the fastener at the cracked hole will decrease, and it will be shed to the adjacent fasteners that will carry higher loads than in uncracked condition. Using currently available computer software, the method presented in this paper provides a relatively quick and quantitatively defined solution to account for the effects of crack length on the fastener loads transfer, and on the far field and bypass loads at each fastener adjacent to the crack. At each location, these variations are determined from the 3-dimensional distribution of stresses in the joint, and accounting for secondary bending effects and fastener tilt. Two cases of a typical skins lap splice with eight fasteners in a two rows configuration loaded in tension are presented and discussed, one representative for wing or fuselage skins configurations, and the second case representative for cost effective laboratory testing. Each case presents five cracking scenarios, with the cracks growing from approx. 0.03 inch to either the free edge, next hole or both simultaneously.展开更多
文摘The binding energy and effective mass of a polaron confined in a GaAs film deposited on an AlGal-xAs substrate are investigated, for different film thickness values and aluminum concentra- tions and within the framework of the fractional-dimensional space approach. Using this scheme, we propose a new method to define the effective length of the quantum confinement. The limita- tions of the definition of the original effective well width are discussed, and the binding energy and effective mass of a polaron confined in a GaAs film are obtained. The fl-actional-dimensional theo- retical results are shown to be in good agreement with previous, more detailed calculations based on second-order perturbation theory.
基金The authors would like to express their great appreciation for funding made possible in support of this research endeavor through the CSU-LSAMP(California State University Louis Stokes Alliance for Minority Participation)program via the NSF(National Science Foundation)grant#HRD-1302873the Chancellor’s Office of the California State University。
文摘The design of columns relies heavily on the basis of Leonhard Euler’s Theory of Elastic Buckling.However,to increase the accuracy in determining the maximum critical load a column can withstand before buckling,a constant was introduced.This dimensionless coefficient is K,also known as the effective-length factor.This constant is often found in building design codes and varies in value depending on the type of column support that is applied.This paper presents experimental and analytical studies on the determination of the effective-length factor in the buckling stability of columns with partially-fixed support conditions.To this end,the accurate K value of the columns tested by the Instron Testing Machine(ITM)at California State University,Northridge’s(CSUN’s)Mechanics Laboratory is determined.The ITM is used in studying the buckling of columns where the supports are neither pinned nor fixed,and the material cross-section rather rests upon the machine while loading is applied axially.Several column specimens were tested and the experimental data were analyzed in order to estimation of the accurate effective-length factor.The calculations from the tested results as well as the conducted probabilistic analysis shed light on how a fragility curve may aid in predicting the effective-length value of future tests.
基金This work was supportedjointly by the National Key Basic Research DevelopmentProgram(G1999043400)and the National Natural ScienceFoundation of China under Grant Nos.40275021,and49975016.
文摘A new method is proposed for the effective roughness length (ERL) in heterogeneous terrain based on the principle of equalisation of momentum or heat fluxes calculated by the drag coefficient parameterization scheme used in the ECMWF numerical model. Compared with the area-weighted logarithmically averaged ERL (drag coefficient), the newly calculated ERL (drag coefficient) is about 40% (16%) larger with a roughness step of 2.3. These differences reach their maximum values when the ratio of smooth to rough surface is 60% to 40%. Since the determination by this method is not sensitive to the atmospheric stratification, it is suitable for use in climate models.
基金supported by the National Major Science and Technology Project“Demonstrative development project of large carbonate gas field in Sichuan Basin”(No.:2016ZX05052).
文摘For the purpose of improving the accuracy and effectiveness of acid fracturing design for carbonate reservoirs with developed natural fractures,an acidizingfluidflow and reaction model taking the multiple leak-off effect of natural fracture,wormhole and matrix into account was established according to the liquid phase reaction equilibrium principle and the local reaction equilibrium principle after the dynamic change of fracture geometry in the process of fracture created by prepadfluid was simulated in the classical pseudo-three dimensional mathematical model of fracture propagation.Then,the acid fracturing stimulation of a case well on site was taken as an example.The newly developed model was used to simulate thefiltration process of acidizingfluid in fractures and the dynamic etching morphology of acidic rocks during the acidizingfluid injection of prepad acid fracturing.The effective length of etched fractures was determined by analyzing the concentration change of acidizingfluid along the direction of hydraulic fracture length and the threshold concentration of residual acidizingfluid comprehensively,and then it was compared with the interpretation result of pressure buildup test.And the following research results were obtained.First,in the process of acid fracturing in fracturedeporous reservoirs,the acidizingfluidfiltration velocity along the direction of fracture length is not constant and thefiltration velocity curvefluctuates in a serrated shape.And the acidizingfluidfiltration velocity where etched wormholes meet natural fractures is commonly higher than that in matrix.Second,acidizingfluid is lost seriously and the effective distance of acidizingfluid gets short significantly during the acid fracturing of fracturedeporous reservoirs.Third,acid fracturing in the verification well is remarkable in blockage removing and stimulation,and its well test interpretation results are consistent with the simulation interpretation results provided by the newly developed mathematical model.It is indicated that this newly developed model is reliable.In conclusion,the mathematical model of prepad acid fracturing which considers multiple leak-off effect is more suitable for acid fracturing simulation of fracturedeporous reservoirs.
文摘This article describes the effective channel length degradation under hot carrier stressing. The extraction is based on the IDs-Vcs characteristics by maximum transconductance （maximum slope of IDs ＆ VGS） in the linear region. The transconductance characteristics are determine for the several devices of difference drawn channel length. The effective channel length of submicron LDD （Lightly Doped Drain） NMOSFETs （Metal Oxide Semiconductor Field Effect Transistor） under hot carrier stressing was measured at the stress time varying from zero to 10,000 seconds. It is shown that the effective channel length was increased with time. This is caused by charges trapping in the oxide during stress. The increased of effective channel length （△Leff） is seem to be increased sharply as the gate channel length is decrease.
基金supported by the National Natural Science Foundation of China(51208047)
文摘The calculation equation of large diameter bored pile＇s effective length is connected with its distribution of pile shaft resistance. Thus, there is a great difference between the calculation results under the different distributions of pile shaft resistance. Primarily, this paper summarizes the conceptualized mode of pile shaft resistance under the circum- stance that the soil surrounding the piles presents different layer distributions. Secondly, based on Mindlin＇s displacement solution and in consideration of the effect of pile diam- eter, the calculation equation is optimized with the assumption that the pile shaft resis- tance has a parabolic distribution. The influencing factors are analyzed according to the calculation result of effective pile length. Finally, combined with an engineering example, the calculation equation deduced in this paper is analyzed and verified. The result shows that both the Poisson ratio of soil and pile diameter have impacted the effective pile length. Compared with the Poisson ratio of soil, the effect of pile diameter is more significant. If the pile diameter remains the same, the effect of the Poisson ratio of soil to the effective pile length decreases as the ratio of pile elastic modulus and soil share modulus increases. If the Poisson ratio of soil remains the same, the effect of the pile diameter to the effective pile length increases as the ratio of pile elastic modulus and soil share modulus increases. Thus the optimized calculation result of pile effective length under the consideration of pile diameter effect is more close to the actual situation of engineering and reasonably practicable.
基金supported by the Vietnam National Foundation for Science and Technology Development(NAFOSTED)(No.107.02-2017.310)。
文摘The present work is concerned with a two-dimensional(2D)Stokes flow through a channel bounded by two parallel solid walls.The distance between the walls may be arbitrary,and the surface of one of the walls can be arbitrarily rough.The main objective of this work consists in homogenizing the heterogeneous interface between the rough wall and fluid so as to obtain an equivalent smooth slippery fluid/solid interface characterized by an effective slip length.To solve the corresponding problem,two efficient numerical approaches are elaborated on the basis of the method of fundamental solution(MFS)and the boundary element methods(BEMs).They are applied to different cases where the fluid/solid interface is periodically or randomly rough.The results obtained by the proposed two methods are compared with those given by the finite element method and some relevant ones reported in the literature.This comparison shows that the two proposed methods are particularly efficient and accurate.
基金Supported by the Fundamental Research Funds for the Central Universities under Grant No ZYGX2009X008
文摘Based on the generalized uncertainty principle with maximum momentum arid minimal length, we discuss the equation of state of ideal ultra-relativistic Fermi gases at zero temperature. Maximum momentum avoids the problem that the Fermi degenerate pressure blows up since the increase of the Fermi energy is not limited. Applying this equation of state to the Tolman-Oppenheimer Volkoff （TOV） equation, the quantum gravitational effects on the cores of compact stars are discussed. In the center of compact stars, we obtain the singularity-free solution of the metric component, gtt ～-（1 ＋ 0.2185×r^2）. By numerically solving the TOV equation, we find that quantum gravity plays an important role in the region r～10^4α0（△x）min. Current observed masses of neutron stars indicate that the dimensionless parameter α0 cannot exceed 10^19.
文摘The effect of day length and temperature on the pollen fertility of five photoperiod-sensitive genic male-sterile japonica rice lines (PGMSR) and three temperature-sensitive genic malesterile indica rice lines (TGMSR) were investigated in phytotron. The light source used for illumination was xenon lamp, and the light intensity which plant accepted on the leaf surface was 300—350μmol photons ms. The results indicated that pollens of PGMSR 7001S and E47S aborted completely whereas a little part of 31116S pollens appeared normal under long day photoperiod (LD,25℃,15h) (Table 1). High temperature (HT, 30℃, 12h) and lower temperature (LT,
文摘In this work,the results of an experimental study of the impulse characteristic of practical ground electrodes consisting of horizontal conductors of various lengths and full-scale tower footings were reported.These electrodes were installed at an outdoor test site having nonuniform soil,with equipment facilities for generating low-and high-magnitude impulse currents.The tests on the horizontal electrode were used to determine the effective length,the voltage and current distribution along the electrode length and the effect of the injection point along the electrode.The tests on the tower footings were used to determine impulse resistance and demonstrate its non-linear variation with current magnitude.Computer simulations of the test electrodes using the electromagnetic field method showed good agreement with the measured result.
文摘The forbidden pitch ＂dip＂ in the critical dimension （CD） through the pitch curve is a well-known optical proximity effect. The CD and CD process window near the ＂dip＂,usually found near a pitch range of 1.1 to 1.4 wavelength/ NA （numerical aperture）,is smaller when compared with other pitches. This is caused by inadequate imaging contrast for an unequal line and space grating. Although this effect is relatively well-known, its relationship with typical process condition parameters,such as the effective image blur caused by the photo-acid diffusion during the post exposure bake or the aberration in the imaging lens, has not been systematically studied. In this paper, we will examine the correlation between the image blur and the effect on the CD, including the decrease in the CD value （the depth of the ＂dip＂） and the CD process window. We find that both the decrease in the CD value and the focus latitude near the forbidden pitch correlate very well with the effective Gaussian image blur. Longer effective diffusion length correlates well with a smaller process window and a deeper CD ＂dip＂. We conclude that the dip depth is very sensitive to the change in image contrast.
文摘By means of the functionality distribution deduced and weight averaged functionality a and molecular size vb2, the sol-gel distribution equations of HTPB(Hydroxyl terminated polybutadiene) + TDI (Toluene-2, 4-diisocyanate) expressed by the model of Aai-B2 type polycondensation were solved and the elastic modulus were calculated. The experimental results of HTPB+TDI curing process indicate that a, vb2 and functionality distribution function are available basically.
基金Funded by the National Natural Science Foundation of China(50178026)the Cheung Kong Scholars Program Foundation of Chinese Ministry of Education(2009-37)
文摘The main reaction products were investigated by analysis of microstructure of alkali-activated ground granulated blast furnace slag （GGBFS） paste. An experimental research was performed on bond performance of alkali-activated GGBFS paste as a construction adhesive after exposure to 20-500℃. Through XRD analysis, a few calcium silicate hydrate, hydrotalcite and tetracalcium aluminate hydrate were determined as end products, and they were filled and packed each other at room temperature. In addition, akermanite dramatically increased at 800 ~C and above. The two key parameters, the ultimate load Pu.T and effective bond length Le, were determined using test data of carbon fiber-reinforced polymer （CFRP）-to-concrete bonded joints at elevated temperature. The experimental results indicate that the ultimate load Pu.T remains relatively stable initially and then decreases with increasing temperature. The effective bond length Le increases with increasing temperature except at 300℃. The proposed temperature-dependent effective bond length formula is shown to closely represent the test data.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.40930952,40875040,and 41005043)the Special Project for Public Welfare Enterprises(Grant No.GYHY200806005)the National Science/Technology Support Program of China(Grant Nos.2007BAC29B01 and 2009BAC51B04)
文摘By establishing the Markov model for a long-range correlated time series （LRCS） and analysing its evolutionary characteristics, this paper defines a physical effective correlation length （ECL） T, which reflects the predictability of the LRCS. It also finds that the ECL has a better power law relation with the long-range correlated exponent γ of the LRCS： T = Kexp（-γ/0.3） ＋ Y, （0 〈 γ〈 1） the predictability of the LRCS decays exponentially with the increase of γ It is then applied to a daily maximum temperature series （DMTS） recorded at 740 stations in China between the years 1960-2005 and calculates the ECL of the DMTS. The results show the remarkable regional distributive feature that the ECL is about 10-14 days in west, northwest and northern China, and about 5-10 days in east, southeast and southern China. Namely, the predictability of the DMTS is higher in central-west China than in east and southeast China. In addition, the ECL is reduced by 1-8 days in most areas of China after subtracting the seasonal oscillation signal of the DMTS from its original DMTS; however, it is only slightly altered when the decadal linear trend is removed from the original DMTS. Therefore, it is shown that seasonal oscillation is a significant component of daily maximum temperature evolution and may provide a basis for predicting daily maximum temperatures. Seasonal oscillation is also significant for guiding general weather predictions, as well as seasonal weather predictions.
基金Project supported by the State Key Project of Research and Development of China(Grant No.2017YFA0206302)the National Nature Science Foundation of China(Grant Nos.51590883,51331006,and 51471167)the Chinese Academy of Sciences(Grant No.KJZD-EW-M05-3)
文摘Experimental and theoretical researches on nanostructured exchange coupled magnets have been carried out since about 1988. Here, we review the structure and magnetic properties of the anisotropic nanocomposite soft/hard multilayer magnets including some new results and phenomena from an experimental point of view. According to the different component of the oriented hard phase in the nanocomposite soft/hard multilayer magnets, three types of magnets will be discussed：1） anisotropic Nd2Fe（14）B based nanocomposite multilayer magnets, 2） anisotropic SmCo5 based nanocomposite multilayer magnets, and 3） anisotropic rare-earth free based nanocomposite multilayer magnets. For each of them, the formation of the oriented hard phase, exchange coupling, coercivity mechanism, and magnetic properties of the corresponding anisotropic nanocomposite multilayer magnets are briefly reviewed, and then the prospect of realization of bulk magnets on new results of anisotropic nanocomposite multilayer magnets will be carried out.
基金Supported by the National Basic Research Program of China(973 Program)(No.2015CB453302)the NSFC-Shandong Joint Fund for Marine Science Research Centre(No.U1606404)the Aoshan Science and Technology Innovation Project(No.2015ASKJ02-04)
文摘Removal of the length ef fect in otolith shape analysis for stock identification using length scaling is an important issue; however, few studies have attempted to investigate the ef fectiveness or weakness of this methodology in application. The aim of this study was to evaluate whether commonly used size scaling methods and normalized elliptic Fourier descriptors(NEFDs) could ef fectively remove the size ef fect of fish in stock discrimination. To achieve this goal, length groups from two known geographical stocks of yellow croaker, L arimichthys polyactis, along the Chinese coast(five groups from the Changjiang River estuary of the East China Sea and three groups from the Bohai Sea) were subjected to otolith shape analysis. The results indicated that the variation of otolith shape caused by intra-stock fish length might exceed that due to inter-stock geographical separation, even when otolith shape variables are standardized with length scaling methods. This variation could easily result in misleading stock discrimination through otolith shape analysis. Therefore, conclusions about fish stock structure should be carefully drawn from otolith shape analysis because the observed discrimination may primarily be due to length ef fects, rather than dif ferences among stocks. The application of multiple methods, such as otoliths shape analysis combined with elemental fingering, tagging or genetic analysis, is recommended for sock identification.
基金Supported by the National Natural Science Foundation of China (No. 60872075)
文摘To solve the difficulty of designing digital impacting filter in the receiver of random-polar modulated Extended Binary Phase Shift Keying with Continuous Phase (CP-EBPSK), a design method based on Quantum-behaved Particle Swarm Optimization (QPSO) algorithm is proposed. Firstly, QPSO is introduced elaborately, and the basic flow of QPSO is also given. Then, the demodulation principle of digital impacting filter in the communication system of CP-EBPSK with random-polar is demonstrated, and QPSO is utilized to design the digital impacting filter, which also takes the effect of finite word length into consideration when implemented by hardware. Finally, the proposed method is simulated. Simulation results show that the digital impacting filter designed by new method can derive satisfied demodulation performance.
基金supported by the National Natural Science Funding of China(31272711,31330034,9184910039and 3207090129 to M.S.Z)。
文摘Airway smooth muscle(ASM)has developed a mechanical adaption mechanism by which it transduces force and responds to environmental forces,which is essential for periodic breathing.Cytoskeletal reorganization has been implicated in this process,but the regulatory mechanism remains to be determined.We here observe that ASM abundantly expresses cytoskeleton regulators Limk1 and Limk2,and their expression levels are further upregulated in chronic obstructive pulmonary disease(COPD)animals.By establishing mouse lines with deletions of Limk1 or Limk2,we analyse the length-sensitive contraction,F/Gactin dynamics,and F-actin pool of mutant ASM cells.As LIMK1 phosphorylation does not respond to the contractile stimulation,LIMK1-deficient ASM develops normal maximal force,while LIMK2 or LIMK1/LIMK2 deficient ASMs show approximately 30%inhibition.LIMK2 deletion causes a significant decrease in cofilin phosphorylation along with a reduced F/G-actin ratio.As LIMK2 functions independently of cross-bridge movement,this observation indicates that LIMK2 is necessary for F-actin dynamics and hence force transduction.Moreover,LIMK2-deficient ASMs display abolishes stretching-induced suppression of 5-hydroxytryptamine(5-HT)but not acetylcholine-evoks force,which is due to the differential contraction mechanisms adopted by the agonists.We propose that LIMK2-mediated cofilin phosphorylation is required for membrane cytoskeleton reorganization that is necessary for ASM mechanical adaption including the 5-HT-evoked length-sensitive effect.
文摘High strength threaded fasteners are widely used in the aircraft industry, and service experience shows that for structures where shear loading of the joints is significant, like skin splices, fuselage joints or spar caps-web attachments, more cracks are initiated and grow from the edges of the fastener holes than from features like fillets radii and corners or from large access holes. The main causes of this cracking are the stress concentrations introduced by the fastener holes and by the threaded fasteners themselves, with the most common damage site being at the edge of the fastener holes. Intuitively, it is easy to visualize that after the crack initiation, during the growth stages, some of the load transferred initially by the fastener at the cracked hole will decrease, and it will be shed to the adjacent fasteners that will carry higher loads than in uncracked condition. Using currently available computer software, the method presented in this paper provides a relatively quick and quantitatively defined solution to account for the effects of crack length on the fastener loads transfer, and on the far field and bypass loads at each fastener adjacent to the crack. At each location, these variations are determined from the 3-dimensional distribution of stresses in the joint, and accounting for secondary bending effects and fastener tilt. Two cases of a typical skins lap splice with eight fasteners in a two rows configuration loaded in tension are presented and discussed, one representative for wing or fuselage skins configurations, and the second case representative for cost effective laboratory testing. Each case presents five cracking scenarios, with the cracks growing from approx. 0.03 inch to either the free edge, next hole or both simultaneously.
