Periodic solitons are studied in dispersion decreasing fibers with a cosine profile. The variable-coefficient nonlinear Schrrdinger equation, which can be used to describe the propagation of solitons, is investigated ...Periodic solitons are studied in dispersion decreasing fibers with a cosine profile. The variable-coefficient nonlinear Schrrdinger equation, which can be used to describe the propagation of solitons, is investigated analytically. Analytic soli- ton solutions for this equation are derived with the Hirota＇s bilinear method. Using the soliton solutions, we obtain periodic solitons, and analyze the soliton characteristics. Influences of physical parameters on periodic solitons are discussed. The presented results can be used in optical communication systems and fiber lasers.展开更多
We study localized waves on continuous wave background in an exponential dispersion decreasing fiber with two orthogonal polarization states. We demonstrate that asymmetric W-shaped and M-shaped soliton pulse can be g...We study localized waves on continuous wave background in an exponential dispersion decreasing fiber with two orthogonal polarization states. We demonstrate that asymmetric W-shaped and M-shaped soliton pulse can be generated from a weak modulation on continuous wave background. The numerical simulation results indicate that the generated asymmetric soliton pulses are robust against small noise or perturbation. In particular, the asymmetric degree of the asymmetric soliton pulse can be effectively controlled by changing the relative frequency of the two components. This character can be used to generate other nonlinear localized waves, such as dark-antidark and antidark-dark soliton pulse pair, symmetric W-shaped and M-shaped soliton pulse. Furthermore, we find that the asymmetric soliton pulse possesses an asymmetric discontinuous spectrum.展开更多
We derive analytical bright and dark solitons of the modified nonlinear Schroedinger equations with variable coefficients. Under constraint conditions between system parameters, the optical soliton transmission in the...We derive analytical bright and dark solitons of the modified nonlinear Schroedinger equations with variable coefficients. Under constraint conditions between system parameters, the optical soliton transmission in the dispersiondecreasing fibers can be exactly controlled by proper dispersion management. The analytical description of the interactions between the bright and dark solitons are first obtained.展开更多
In the paper the problem on the assignment of the bounds of decreasing rate for a time-varying linear control system is discussed. The sufficient and necessary condition for bounds of decreasing rate of a time-varying...In the paper the problem on the assignment of the bounds of decreasing rate for a time-varying linear control system is discussed. The sufficient and necessary condition for bounds of decreasing rate of a time-varying linear system to be assigned arbitrarily is presented. It is pointed out that for any given real number m, M, m<M, there exists a linear state feedback with time-varying gain matrix which makes the corresponding closed-loop system possess M and m as its upper bound and lower bound of the decreasing rate respectively. For the purposes of its application to system design the concept of the asymptotic assignment of the bounds of decreasing rate is also proposed. The method dealing with the asymptotic assignment is given too.展开更多
In this note,by introudcing a couple of parameters T,t and estimating the weight function effectively,Hilberts integral inequalities are well generalized. As applications,we give some new Hilbers type inequalities.
To quantitatively determine the effect of different factors such as fracture width,dip angle,extension and filling material on Stoneley wave amplitude decreasing,the shock tube experiment method was changed from fixin...To quantitatively determine the effect of different factors such as fracture width,dip angle,extension and filling material on Stoneley wave amplitude decreasing,the shock tube experiment method was changed from fixing the sample and vertically moving the sensor in the borehole to fixing the sensors along the shock tube wall and vertically moving the sample without drilling the borehole in it.The measurement accuracy and the signal-to-noise ratio of the first Stoneley wave were improved by the time corrections and amplitude corrections of Stoneley wave signals.At the same time,21 sets of core models with different fracture parameters were processed for this measurement method by using full-diameter carbonate core,and relative amplitudes were defined to characterize Stoneley wave amplitude decreasing.The experimental results show that the relative amplitude of Stoneley wave exponentially decreases with increasing fracture width.The relative amplitude of Stoneley wave linearly decreases with increasing fracture dip angle.The relative amplitude of Stoneley wave exponentially decreases with increasing fracture extension.The relative amplitude of Stoneley wave decreases with increasing the permeability of filling material in the fracture.Under the above four conditions,the fracture width has the greatest effect on the decreasing of Stoneley wave amplitude,followed by the fracture extension and the permeability of filling material,and finally the fracture dip angle.展开更多
The temperature dependences of magnetostriction in Pr（1 x）DyxFe（1.9）（0 ≤ x ≤ 1.0） alloys between 5 K and 300 K were investigated.An unusual decrease of magnetostriction with temperature decreasing was found in...The temperature dependences of magnetostriction in Pr（1 x）DyxFe（1.9）（0 ≤ x ≤ 1.0） alloys between 5 K and 300 K were investigated.An unusual decrease of magnetostriction with temperature decreasing was found in Pr-rich alloys（0 ≤x ≤ 0.2）,due to the change of the easy magnetization direction（EMD）.Dy substitution reduces the magnetostriction in high-magnetic field（10 kOe ≤ H≤90 kOe） at 5 K,while a small amount of Dy substitution（x = 0.05） is beneficial to increasing the magnetostriction in low-magnetic field between 10 K and 50 K.This makes the alloys a potential candidate for low temperature applications.展开更多
Some color centers in diamond can serve as quantum bits which can be manipulated with microwave pulses and read out with laser,even at room temperature.However,the photon collection efficiency of bulk diamond is great...Some color centers in diamond can serve as quantum bits which can be manipulated with microwave pulses and read out with laser,even at room temperature.However,the photon collection efficiency of bulk diamond is greatly reduced by refraction at the diamond/air interface.To address this issue,we fabricated arrays of diamond nanostructures,differing in both diameter and top end shape,with HSQ and Cr as the etching mask materials,aiming toward large scale fabrication of single-photon sources with enhanced collection efficiency made of nitrogen vacancy（NV） embedded diamond.With a mixture of O2 and CHF3 gas plasma,diamond pillars with diameters down to 45 nm were obtained.The top end shape evolution has been represented with a simple model.The tests of size dependent single-photon properties confirmed an improved single-photon collection efficiency enhancement,larger than tenfold,and a mild decrease of decoherence time with decreasing pillar diameter was observed as expected.These results provide useful information for future applications of nanostructured diamond as a single-photon source.展开更多
A multi-electrode array is commonly applied in a plasma sparker to generate stable acoustic pulses.In this paper, the effects of the electrode configuration on the performance of a plasma sparker have been investigate...A multi-electrode array is commonly applied in a plasma sparker to generate stable acoustic pulses.In this paper, the effects of the electrode configuration on the performance of a plasma sparker have been investigated. In terms of the load electrical characteristics, the electrode radius and distance have negligible influence on the electric characteristics, whereas a larger electrode number results in a smaller voltage and a larger current but has little effect on the load energy. Regarding the acoustic characteristics, both the expansion and collapse pulses can be increased by decreasing the electrode tip radius. the influence of the electrode number and electrode gap distance on the amplitude of the expansion pulse was found to be negligible. And the amplitude of the collapse pulse decreases significantly with increasing electrode number. Increasing the electrode number decreases the energy efficiency for intense bubble interactions, thus, a small electrode tip radius and a small electrode number are preferred for the design of a plasma sparker if the total discharge energy is given.展开更多
The comparison of the electron transport properties is presented under nonuniform fields with their local fields in oxygen.The electron swarm parameters are calculated by using Monte Carlo simulation.The results show ...The comparison of the electron transport properties is presented under nonuniform fields with their local fields in oxygen.The electron swarm parameters are calculated by using Monte Carlo simulation.The results show that there are relatively more electrons distributing in the high-energy range for the decreasing field than the local field,while less for the increasing field,compared with the uniform field.The effective ionization coefficients for the decreasing field are larger than the equilibrium values,and vice versa for the increasing field.The different behavior of the electron swarms in increasing and/or decreasing field is considered to be the reason of the dependence of the discharge current and the corona inception voltage on the electrode polarity during the surface discharge.展开更多
The frequency characteristics of free oscillation magnetron（FOM） and injection-locked magnetron（ILM） are theoretically investigated.By using the equal power voltage obtained from the experiment data,expressions of...The frequency characteristics of free oscillation magnetron（FOM） and injection-locked magnetron（ILM） are theoretically investigated.By using the equal power voltage obtained from the experiment data,expressions of the frequency and radio frequency（RF） voltage of FOM and ILM,as well as the locking bandwidth,on the anode voltage and magnetic field are derived.With the increase of the anode voltage and the decrease of the magnetic field,the power and its growth rate increase,while the frequency increases and its growth rate decreases.The theoretical frequency and power of FOM agree with the particle-in-cell（PIC） simulation results.Besides,the theoretical trends of the power and frequency with the anode voltage and magnetic field are consistent with the experimental results,which verifies the accuracy of the theory.The theory provides a novel calculation method of frequency characteristics.It can approximately analyze the power and frequency of both FOM and ILM,which promotes the industrial applications of magnetron and microwave energy.展开更多
In 2013,printers in Beijing were totaled at 1669,decreasing by22 from the last year,with prime operating revenues of RMB30.05 billion,increasing by 5% from 2012;total profits of RMB2.88 billion,decreasing by 1%from 20...In 2013,printers in Beijing were totaled at 1669,decreasing by22 from the last year,with prime operating revenues of RMB30.05 billion,increasing by 5% from 2012;total profits of RMB2.88 billion,decreasing by 1%from 2012;total assets of RMB44.03 billion,increasing by 9% from 2012;and workforce in the filed by the end of year of 68236,展开更多
The formation of abnormally low-pressure hydrocarbon reservoirs in petroliferous basins has a close relationship with tectonic uplift and the consequent erosion. In order to understand abnormally low-pressure reservoi...The formation of abnormally low-pressure hydrocarbon reservoirs in petroliferous basins has a close relationship with tectonic uplift and the consequent erosion. In order to understand abnormally low-pressure reservoirs and to provide a scientific basis for exploration and development, we established, through numerical simulation and theoretical analysis, a set of equations for the formation pressure in a closed system influenced by uplift-erosion, discussed the relationship between the genesis of abnormal pressure and uplift-erosion, and put forward the concept of balance pressure （P b ）. The results showed that abnormally high pressure coefficient may form when the current formation pressure was higher than P b , and abnormally low pressure may form when the current formation pressure was lower than P b . In the Santanghu Basin, the current formation pressure of abnormally low pressure reservoirs is lower than P b , so tectonic uplift-erosion leads to the decrease of the pressure coefficient. There is a positive correlation between the pressure drop caused by the decrease of fluid temperature and the rebound of rock porosity and strata erosion. Calculation results indicated that the reservoir pressure of Jurassic strata in the Santanghu Basin was decreased by 11.6-17.1 MPa due to tectonic uplift-erosion during the Late Yanshanian period.展开更多
The progress of the GAG gas flow in a conveyor drift is investigated.The output of a calculation model is evaluated and compared with experimental results from full-scale inertisation experiments.Expressions presentin...The progress of the GAG gas flow in a conveyor drift is investigated.The output of a calculation model is evaluated and compared with experimental results from full-scale inertisation experiments.Expressions presenting the fastest and most extensive condensation of water resulted in well fitted arrival times of the GAG gas front.A common denominator for the two sets of expressions is that the type of flow is considered and thus better fitted to the actual flow situation.The model was further refined to include the surface roughness factor in the condensation calculations,which resulted in time lengths even closer to the measured time length.The measured rapid temperature increase at certain positions along the conveyor drift was found to fit well with the calculated GAG gas front arrival at the corresponding positions.The magnitude of the GAG flow was found to have a large impact on the arrival time of the GAG gas front.Knowing and understanding the GAG gas behaviour would increase the likelihood of successful inertisation of all or part of a mine.展开更多
The geographical distribution and the abundance of Moose(Alces alces)popula-tion were studied in Northeastern China between 1985 and 1987,309 trails on the snow crossingthe 2,446km sampling lines were counted.The Moos...The geographical distribution and the abundance of Moose(Alces alces)popula-tion were studied in Northeastern China between 1985 and 1987,309 trails on the snow crossingthe 2,446km sampling lines were counted.The Moose range had been shrunked to northwest for100-200 km since 1976,and at present they covered an area about 190,000 km^2.The densitiesvaried from 0.0187 Mooses/km^2 to 0.1226 Mooses/km^2 and the average was 0.0519Mooses/km^2.The Moose population size was 9,955±397 Mooses(α=0.2,P=84.5%),about7000 of them was distributed in Daxinganling Mountains and the others were in XiaoxinganlingMountains.The present population had decreased to 53.4%in 1976,and the annual decreaserate was 6.27%.At present,Moose population is likely rare in China and should be strictly pro-tected.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61205064,51272202,and 61234006)the Visiting Scholar Funds of the Key Laboratory of Optoelectronic Technology and Systems of Chongqing University(Grant No.0902011812401 5)
文摘Periodic solitons are studied in dispersion decreasing fibers with a cosine profile. The variable-coefficient nonlinear Schrrdinger equation, which can be used to describe the propagation of solitons, is investigated analytically. Analytic soli- ton solutions for this equation are derived with the Hirota＇s bilinear method. Using the soliton solutions, we obtain periodic solitons, and analyze the soliton characteristics. Influences of physical parameters on periodic solitons are discussed. The presented results can be used in optical communication systems and fiber lasers.
基金Project supported by the National Natural Science Foundation of China(Grant No.11475135)the Fund from Shaanxi Province Science Association of Colleges and Universities(Grant No.20160216)Guangxi Provincial Education Department Research Project,China(Grant No.2017KY0776)
文摘We study localized waves on continuous wave background in an exponential dispersion decreasing fiber with two orthogonal polarization states. We demonstrate that asymmetric W-shaped and M-shaped soliton pulse can be generated from a weak modulation on continuous wave background. The numerical simulation results indicate that the generated asymmetric soliton pulses are robust against small noise or perturbation. In particular, the asymmetric degree of the asymmetric soliton pulse can be effectively controlled by changing the relative frequency of the two components. This character can be used to generate other nonlinear localized waves, such as dark-antidark and antidark-dark soliton pulse pair, symmetric W-shaped and M-shaped soliton pulse. Furthermore, we find that the asymmetric soliton pulse possesses an asymmetric discontinuous spectrum.
基金Project supported by the National Natural Science Foundations of China (Grant No. 11005092)the Program for Innovative Research Team of Young Teachers (Grant No. 2009RC01)the Scientific Research and Developed Fund of Zhejiang Agricultural and Forestry University (Grant No. 2009FK42).
文摘We derive analytical bright and dark solitons of the modified nonlinear Schroedinger equations with variable coefficients. Under constraint conditions between system parameters, the optical soliton transmission in the dispersiondecreasing fibers can be exactly controlled by proper dispersion management. The analytical description of the interactions between the bright and dark solitons are first obtained.
文摘In the paper the problem on the assignment of the bounds of decreasing rate for a time-varying linear control system is discussed. The sufficient and necessary condition for bounds of decreasing rate of a time-varying linear system to be assigned arbitrarily is presented. It is pointed out that for any given real number m, M, m<M, there exists a linear state feedback with time-varying gain matrix which makes the corresponding closed-loop system possess M and m as its upper bound and lower bound of the decreasing rate respectively. For the purposes of its application to system design the concept of the asymptotic assignment of the bounds of decreasing rate is also proposed. The method dealing with the asymptotic assignment is given too.
文摘In this note,by introudcing a couple of parameters T,t and estimating the weight function effectively,Hilberts integral inequalities are well generalized. As applications,we give some new Hilbers type inequalities.
基金Supported by the PetroChina’s Fundamental Research Project(2019A-3609)。
文摘To quantitatively determine the effect of different factors such as fracture width,dip angle,extension and filling material on Stoneley wave amplitude decreasing,the shock tube experiment method was changed from fixing the sample and vertically moving the sensor in the borehole to fixing the sensors along the shock tube wall and vertically moving the sample without drilling the borehole in it.The measurement accuracy and the signal-to-noise ratio of the first Stoneley wave were improved by the time corrections and amplitude corrections of Stoneley wave signals.At the same time,21 sets of core models with different fracture parameters were processed for this measurement method by using full-diameter carbonate core,and relative amplitudes were defined to characterize Stoneley wave amplitude decreasing.The experimental results show that the relative amplitude of Stoneley wave exponentially decreases with increasing fracture width.The relative amplitude of Stoneley wave linearly decreases with increasing fracture dip angle.The relative amplitude of Stoneley wave exponentially decreases with increasing fracture extension.The relative amplitude of Stoneley wave decreases with increasing the permeability of filling material in the fracture.Under the above four conditions,the fracture width has the greatest effect on the decreasing of Stoneley wave amplitude,followed by the fracture extension and the permeability of filling material,and finally the fracture dip angle.
基金Project supported by the National Natural Science Foundation of China(Grant No.U1232210)the Science Foundation of Guangxi Zhuang Autonomous Region,China(Grant No.2015GXNSFBA139020)the Enhancement of the Basic Ability of Teachers of Guangxi Zhuang Autonomous Region,China(Grant No.KY2016YB068)
文摘The temperature dependences of magnetostriction in Pr（1 x）DyxFe（1.9）（0 ≤ x ≤ 1.0） alloys between 5 K and 300 K were investigated.An unusual decrease of magnetostriction with temperature decreasing was found in Pr-rich alloys（0 ≤x ≤ 0.2）,due to the change of the easy magnetization direction（EMD）.Dy substitution reduces the magnetostriction in high-magnetic field（10 kOe ≤ H≤90 kOe） at 5 K,while a small amount of Dy substitution（x = 0.05） is beneficial to increasing the magnetostriction in low-magnetic field between 10 K and 50 K.This makes the alloys a potential candidate for low temperature applications.
基金Project supported by the National Key Research and Development Plan of China(Grant No.2016YFA0200402)the National Natural Science Foundation of China(Grants Nos.11574369,11574368,91323304,11174362,and 51272278)the FP7 Marie Curie Action(project No.295208)sponsored by the European Commission
文摘Some color centers in diamond can serve as quantum bits which can be manipulated with microwave pulses and read out with laser,even at room temperature.However,the photon collection efficiency of bulk diamond is greatly reduced by refraction at the diamond/air interface.To address this issue,we fabricated arrays of diamond nanostructures,differing in both diameter and top end shape,with HSQ and Cr as the etching mask materials,aiming toward large scale fabrication of single-photon sources with enhanced collection efficiency made of nitrogen vacancy（NV） embedded diamond.With a mixture of O2 and CHF3 gas plasma,diamond pillars with diameters down to 45 nm were obtained.The top end shape evolution has been represented with a simple model.The tests of size dependent single-photon properties confirmed an improved single-photon collection efficiency enhancement,larger than tenfold,and a mild decrease of decoherence time with decreasing pillar diameter was observed as expected.These results provide useful information for future applications of nanostructured diamond as a single-photon source.
基金supported by the National Key R&D Program of China under Grant 2016YFC0303901NSFC with grant numbers:U1606401,41476080,21276232 and 51377145+3 种基金Public Science and Technology Research Funds Projects of Ocean with grant number:201405036-2NSF of Zhejiang Province with grant number:LQ14D060004,LY13E070002 and 2014C33022Program for Zhejiang Leading Team of S&T Innovation with grant number:2013TD07Research Fund for the Taishan Scholar Project of Shandong Province with grant number:TSPD20161007
文摘A multi-electrode array is commonly applied in a plasma sparker to generate stable acoustic pulses.In this paper, the effects of the electrode configuration on the performance of a plasma sparker have been investigated. In terms of the load electrical characteristics, the electrode radius and distance have negligible influence on the electric characteristics, whereas a larger electrode number results in a smaller voltage and a larger current but has little effect on the load energy. Regarding the acoustic characteristics, both the expansion and collapse pulses can be increased by decreasing the electrode tip radius. the influence of the electrode number and electrode gap distance on the amplitude of the expansion pulse was found to be negligible. And the amplitude of the collapse pulse decreases significantly with increasing electrode number. Increasing the electrode number decreases the energy efficiency for intense bubble interactions, thus, a small electrode tip radius and a small electrode number are preferred for the design of a plasma sparker if the total discharge energy is given.
文摘The comparison of the electron transport properties is presented under nonuniform fields with their local fields in oxygen.The electron swarm parameters are calculated by using Monte Carlo simulation.The results show that there are relatively more electrons distributing in the high-energy range for the decreasing field than the local field,while less for the increasing field,compared with the uniform field.The effective ionization coefficients for the decreasing field are larger than the equilibrium values,and vice versa for the increasing field.The different behavior of the electron swarms in increasing and/or decreasing field is considered to be the reason of the dependence of the discharge current and the corona inception voltage on the electrode polarity during the surface discharge.
基金Project supported by the National Basic Research Program of China(Grant No.2013CB328901)the National Natural Science Foundation of China(Grant No.11305177)
文摘The frequency characteristics of free oscillation magnetron（FOM） and injection-locked magnetron（ILM） are theoretically investigated.By using the equal power voltage obtained from the experiment data,expressions of the frequency and radio frequency（RF） voltage of FOM and ILM,as well as the locking bandwidth,on the anode voltage and magnetic field are derived.With the increase of the anode voltage and the decrease of the magnetic field,the power and its growth rate increase,while the frequency increases and its growth rate decreases.The theoretical frequency and power of FOM agree with the particle-in-cell（PIC） simulation results.Besides,the theoretical trends of the power and frequency with the anode voltage and magnetic field are consistent with the experimental results,which verifies the accuracy of the theory.The theory provides a novel calculation method of frequency characteristics.It can approximately analyze the power and frequency of both FOM and ILM,which promotes the industrial applications of magnetron and microwave energy.
文摘In 2013,printers in Beijing were totaled at 1669,decreasing by22 from the last year,with prime operating revenues of RMB30.05 billion,increasing by 5% from 2012;total profits of RMB2.88 billion,decreasing by 1%from 2012;total assets of RMB44.03 billion,increasing by 9% from 2012;and workforce in the filed by the end of year of 68236,
基金supported by the National Natural Science Foundation of China (No. 40802027)China "973" Project (No. 2009CB219604)the Risk Innovation Foundation of PetroChina Co. Ltd. (No. 0706d01040102)
文摘The formation of abnormally low-pressure hydrocarbon reservoirs in petroliferous basins has a close relationship with tectonic uplift and the consequent erosion. In order to understand abnormally low-pressure reservoirs and to provide a scientific basis for exploration and development, we established, through numerical simulation and theoretical analysis, a set of equations for the formation pressure in a closed system influenced by uplift-erosion, discussed the relationship between the genesis of abnormal pressure and uplift-erosion, and put forward the concept of balance pressure （P b ）. The results showed that abnormally high pressure coefficient may form when the current formation pressure was higher than P b , and abnormally low pressure may form when the current formation pressure was lower than P b . In the Santanghu Basin, the current formation pressure of abnormally low pressure reservoirs is lower than P b , so tectonic uplift-erosion leads to the decrease of the pressure coefficient. There is a positive correlation between the pressure drop caused by the decrease of fluid temperature and the rebound of rock porosity and strata erosion. Calculation results indicated that the reservoir pressure of Jurassic strata in the Santanghu Basin was decreased by 11.6-17.1 MPa due to tectonic uplift-erosion during the Late Yanshanian period.
文摘The progress of the GAG gas flow in a conveyor drift is investigated.The output of a calculation model is evaluated and compared with experimental results from full-scale inertisation experiments.Expressions presenting the fastest and most extensive condensation of water resulted in well fitted arrival times of the GAG gas front.A common denominator for the two sets of expressions is that the type of flow is considered and thus better fitted to the actual flow situation.The model was further refined to include the surface roughness factor in the condensation calculations,which resulted in time lengths even closer to the measured time length.The measured rapid temperature increase at certain positions along the conveyor drift was found to fit well with the calculated GAG gas front arrival at the corresponding positions.The magnitude of the GAG flow was found to have a large impact on the arrival time of the GAG gas front.Knowing and understanding the GAG gas behaviour would increase the likelihood of successful inertisation of all or part of a mine.
文摘The geographical distribution and the abundance of Moose(Alces alces)popula-tion were studied in Northeastern China between 1985 and 1987,309 trails on the snow crossingthe 2,446km sampling lines were counted.The Moose range had been shrunked to northwest for100-200 km since 1976,and at present they covered an area about 190,000 km^2.The densitiesvaried from 0.0187 Mooses/km^2 to 0.1226 Mooses/km^2 and the average was 0.0519Mooses/km^2.The Moose population size was 9,955±397 Mooses(α=0.2,P=84.5%),about7000 of them was distributed in Daxinganling Mountains and the others were in XiaoxinganlingMountains.The present population had decreased to 53.4%in 1976,and the annual decreaserate was 6.27%.At present,Moose population is likely rare in China and should be strictly pro-tected.
