The mathematical model of the motion of some plane′s flap mechanism is set up by the method of establishing mathematical model of space mechanism. When the input parameter is given, the theoretical output paramet...The mathematical model of the motion of some plane′s flap mechanism is set up by the method of establishing mathematical model of space mechanism. When the input parameter is given, the theoretical output parameter of the flap mechanism is achieved by the model. The wear and tear volume is introduced into the mathematical model, and if the input parameter is the same, the real output parameter of the flap mechanism worn can be obtained. On the basis of this, it is able to achieve the friction and the wear reliability of the flap mechanism.展开更多
An all-atom dimethyl sulfoxide (DMSO) and water model have been used for molecular dynamics simulation. The NMR and IR spectra are also performed to study the structures and interactions in the DMSO-water system. An...An all-atom dimethyl sulfoxide (DMSO) and water model have been used for molecular dynamics simulation. The NMR and IR spectra are also performed to study the structures and interactions in the DMSO-water system. And there are traditional strong hydrogen bonds and weak C-H- ~ ~ O contacts existing in the mixtures according to the analysis of the radial distribution functions. The insight structures in the DMSO-water mixtures can be classified into different regions by the analysis of the hydrogen-bonding network. Interestingly, the molar fraction of DMSO 0.35 is found to be a special concentration by the network. It is the transitional region which is from the water rich region to the DMSO rich region. The stable aggregates of (DMSO)m'S=O…… HW-OW-(H20)n might play a key role in this region. Moreover, the simulation is compared with the chemical shifts in NMR and wavenumbers in IR with concentration dependence. And the statistical results of the average number hydrogen bonds in the MD simulations are in agreement with the experiment data in NMR and IR spectra.展开更多
The thermal elasto-hydrodynamic lubrication characteristics of the internal meshing gears in a planetary gear train under vibrations were examined considering the influence of the modification coefficient and time-var...The thermal elasto-hydrodynamic lubrication characteristics of the internal meshing gears in a planetary gear train under vibrations were examined considering the influence of the modification coefficient and time-varying meshing stiffness.Based on dynamic theory of the gear system,a dynamic model of the planetary gear train was established.The lubrication performances of modified gear systems under vibrations and static loads were analyzed.Compared with other transmission types,the best lubrication effect could be produced by the positive transmission.A thicker lubricating oil film could be formed,and the friction coefficient and oil film flash temperature are the smallest.Increasing modification coefficient improves the lubrication performance continuously but intensifies the engage-in and tooth-change impact.For the planetary and inner gears,the increase in the modification coefficient also leads a decrease in the oil film stiffness.展开更多
We propose a new two-fold integration transformation in p-q phase space∫∫^∞-∞dpdq/π e^2i(p-x)(q-y)f(p,q)≡G(x,y),which possesses some well-behaved transformation properties. We apply this transformation t...We propose a new two-fold integration transformation in p-q phase space∫∫^∞-∞dpdq/π e^2i(p-x)(q-y)f(p,q)≡G(x,y),which possesses some well-behaved transformation properties. We apply this transformation to the Weyl ordering of operators, especially those Q-P ordered and P-Q ordered operators.展开更多
The adsorption and reaction of formic acid (HCOOH) on clean and atomic oxygen‐covered Au(997) surfaces were studied by temperature‐programmed desorption/reaction spectroscopy (TPRS) and X‐ray photoelectron sp...The adsorption and reaction of formic acid (HCOOH) on clean and atomic oxygen‐covered Au(997) surfaces were studied by temperature‐programmed desorption/reaction spectroscopy (TPRS) and X‐ray photoelectron spectroscopy (XPS). At 105 K, HCOOH molecularly adsorbs on clean Au(997) and interacts more strongly with low‐coordinated Au atoms at (111) step sites than with those at (111) terrace sites. On an atomic oxygen‐covered Au(997) surface, HCOOH reacts with oxygen at‐oms to form HCOO and OH at 105 K. Upon subsequent heating, surface reactions occur among ad‐sorbed HCOO, OH, and atomic oxygen and produce CO2, H2O, and HCOOH between 250 and 400 K. The Au(111) steps bind surface adsorbates more strongly than the Au(111) terraces and exhibit larger barriers for HCOO(a) oxidation reactions. The surface reactions also depend on the relative coverages of co‐existing surface species. Our results elucidate the elementary surface reactions between formic acid and oxygen adatoms on Au surfaces and highlight the effects of the coordina‐tion number of the Au atoms on the Au catalysis.展开更多
A 3 × 3 matrix spectral problem and a Liouville integrable hierarchy are constructed by designing a new subalgebra of loop algebra A^-2. Furthermore, high-order binary symmetry constraints of the corresponding hi...A 3 × 3 matrix spectral problem and a Liouville integrable hierarchy are constructed by designing a new subalgebra of loop algebra A^-2. Furthermore, high-order binary symmetry constraints of the corresponding hierarchy are obtained by using the binary nonlinearization method. Finally, according to another new subalgebra of loop algebra A^-2, its integrable couplings are established.展开更多
Objective: The aim of the study was to study the effect of the size and location of tumors on the normal lung dose-volume parameters for lung cancer. Methods: Three spheres with diameters of 2, 3 and 4 cm made of ti...Objective: The aim of the study was to study the effect of the size and location of tumors on the normal lung dose-volume parameters for lung cancer. Methods: Three spheres with diameters of 2, 3 and 4 cm made of tissue-equivalent materials used for simulating tumors were inserted into the upper lobe, middle lobe, lower lobe of the right lung, upper lobe, lower lobe of the left lung of the Rando phantom, respectively. Five-field simplified IMRT (slMRT) planning were designed. The prescribed dose was 60 Gy/2 Gy/30 f, 99% of the planning target volume received this dose. Dose-volume parameters of normal lung tissues including relative volume of lung receiving 〉 5, 10, 20, 30 and 50 Gy (V5, Vl0, V2o, V30, V50), and mean lung dose (MLD) were analyzed and compared. Results: For the dose-volume parameters, the diameter and the position of the tumor had a significant effect (P 〈 0.05). With the diameter expanding from 2 to 3 cm, the parameters associated with tumor lying in various lobes increased by a range between 3.83%-125.38%, while the parameters linked with tumors on different lobes increased by a range between 10.46%-51.46% with the diameter expanding from 3 to 4 cm. Conclusion: Location and size of sphere-like tumor have an obvious effect on dose-volume parameters. Knowing about the degree of influence will help oncologists and physicists better evaluate treatment planning, then the probability of radiation pneumonitis can be reduced.展开更多
Compared to potential temperature (θ) in the dry atmosphere and equivalent potential temperature (θc) in the saturated atmosphere, generalized potential tem- perature (θ") has already proven a better thermod...Compared to potential temperature (θ) in the dry atmosphere and equivalent potential temperature (θc) in the saturated atmosphere, generalized potential tem- perature (θ") has already proven a better thermodynamic parameter in describing the non-uniformly saturated real atmosphere. To add otherwise absent graphic explanations, this paper first presents the physical definition of θ through a tephigram. Then, the utility of the measurement in identifying and forecasting the locations of precipita- tion maxima and heat wave areas with diagnostic com- parison studies and traditionally used thermodynamic parameters is shown.展开更多
This study takes two undergraduate courses of Grade 2011 and 2012 of tourism management in an independent college as the sample, uses the questionnaires and the interviews to obtain the relevant data, analyzes the ten...This study takes two undergraduate courses of Grade 2011 and 2012 of tourism management in an independent college as the sample, uses the questionnaires and the interviews to obtain the relevant data, analyzes the tendency of the bilingual learning of the students, and then uses the data analysis to draw the factors influencing the bilingual teaching effect. Based on the above data analysis, the paper puts forward the composition elements and the implementation path of the bilingual teaching systems of the tourism management specialty in indeoendent colleges.展开更多
The paper first gives a brief overview of the use of statistical methods in sociology in order to show the continuity and importance of these methods in the development of sociology as a science. Therefore, education ...The paper first gives a brief overview of the use of statistical methods in sociology in order to show the continuity and importance of these methods in the development of sociology as a science. Therefore, education of sociologists requires, among other things, training in statistical methods applicable in data processing and analysis in sociological research. Then the research continues with a comparative analysis of the curricula of undergraduate academic studies of sociology, and especially the presence of statistics teaching in them, in the Republic of Serbia and the neighbouring countries. Different programs of the Department of Sociology of the Faculty of Philosophy in Novi Sad are analyzed together with the results of the students' evaluations for the academic years 2007/2008 and 2009/2010.展开更多
To investigate the behaviors of Cu^(2+)and Ni^(2+)with the change of conditions in Cu_(2+)−Ni_(2+)−NH_(3)−NH_(4)+−C_(2)O_(4)^(2-)−H_(2)O reaction system,mathematical models of thermodynamics based on the principle of ...To investigate the behaviors of Cu^(2+)and Ni^(2+)with the change of conditions in Cu_(2+)−Ni_(2+)−NH_(3)−NH_(4)+−C_(2)O_(4)^(2-)−H_(2)O reaction system,mathematical models of thermodynamics based on the principle of mass conservation were established.The simulation results indicate that the precipitation of metal ions from the aqueous phase is a complicated dynamic equilibrium process,during which the coordination reactions of Cu^(2+)and Ni^(2+)with NH3 forming[Cu(NH3)n]^(2+)(n=3−5)and[Ni(NH3)m]^(2+)(m=3−6)are predominant under high pH conditions,respectively.The pH ranges for the simultaneous precipitation of Cu^(2+)and Ni^(2+)are 2.0−6.5 and 2.0−5.5 when[NH3]T equals 0.6 and 4.2 mol/L,respectively,with the prefixed[C_(2)O_(4)^(2-)]T of 0.6 mol/L.Due to the fractional precipitation of Cu^(2+)and Ni^(2+),Cu−Ni composite is obtained after the thermal decomposition of Cu−Ni oxalate complex salts prepared in a pure water system when pH>7.0.By applying the mixed solvent(water/ethanol)as the precipitation medium,the Cu−Ni alloy rods can be finally fabricated with high purity and crystallinity.展开更多
Benford's law is logarithmic law for distribution of leading digits formulated by P[D=d]= log(1+1/d) where d is leading digit or group of digits. It's named by Frank Albert Benford (1938) who formulated mathema...Benford's law is logarithmic law for distribution of leading digits formulated by P[D=d]= log(1+1/d) where d is leading digit or group of digits. It's named by Frank Albert Benford (1938) who formulated mathematical model of this probability. Befbre him, the same observation was made by Simon Newcomb. This law has changed usual preasumption of equal probability of each digit on each position in number.The main characteristic properties of this law are base, scale, sum, inverse and product invariance. Base invariance means that logarithmic law is valid for any base. Inverse invariance means that logarithmic law for leading digits holds for inverse values in sample. Multiplication invariance means that if random variable X follows Benford's law and Y is arbitrary random variable with continuous density then XY follows Benford's law too. Sum invariance means that sums of significand are the same for any leading digit or group of digits. In this text method of testing sum invariance property is proposed.展开更多
Approximate analytical solutions of the D-dimensional Klein-Gordon equation are obtained for the scalarand vector general Hulthen-type potential and position-dependent mass with any l by using the concept of supersymm...Approximate analytical solutions of the D-dimensional Klein-Gordon equation are obtained for the scalarand vector general Hulthen-type potential and position-dependent mass with any l by using the concept of supersymmetricquantum mechanics (SUSYQM).The problem is numerically discussed for some cases of parameters.展开更多
The stability constants of Sb^5+with Cl−as well as thermodynamics of the Sb−S−Cl−H2O system were calculated.The stability constants of Sb5+with Cl−were obtained by theoretical calculations of the absorbance of a Sb5+-...The stability constants of Sb^5+with Cl−as well as thermodynamics of the Sb−S−Cl−H2O system were calculated.The stability constants of Sb5+with Cl−were obtained by theoretical calculations of the absorbance of a Sb5+-containing solution at different Cl^−concentrations,which was detected by spectrophotometric analysis at certain wavelengths of light(380 nm).The logarithmic values versus 10 of stability constants of Sb^5+with Cl−were 1.795,3.150,4.191,4.955,5.427 and 5.511,respectively,and partly filled the data gaps in the hydrometallurgy of antimony.The presence and distribution of pentavalent antimony compounds under different conditions were analyzed based on equilibrium calculations.Thermodynamic equilibrium calculations were performed for Sb−S−Cl−H2O system,which included the complex behavior of Sb with Cl,and the equilibrium equations of related reactions in this system were integrated into the potential−pH diagram.展开更多
The thermal elastohydrodynamic lubrication characteristics of a modified gear system under a dynamic load were investigated,including the influence of the modification coefficient and vibrations.Based on the dynamic t...The thermal elastohydrodynamic lubrication characteristics of a modified gear system under a dynamic load were investigated,including the influence of the modification coefficient and vibrations.Based on the dynamic theory of gear systems,a six-degree-of-freedom tribo-dynamics model was established.Thermal elastohydrodynamic lubrication characteristics of a modified gear system under vibrations and a static load were analyzed.The results showed that the positive transmission gear system exhibited the better lubrication effect compared with other transmission types.A thick lubricating oil film could be formed,and the friction coefficient between the teeth and the oil film flash temperature were the smallest.As the modification coefficient increased,the lubrication condition was continuously improved,and the scuffing load capacity was enhanced.The increment of the modification coefficient increased the meshing stiffness of the gear system but reduced the stiffness of the oil film.展开更多
A novel kind of optical fiber instrument for two channel measurement of temperature and displacement was developed. Four channel quartz fiber optics were employed to measure two channel signals of temperature and disp...A novel kind of optical fiber instrument for two channel measurement of temperature and displacement was developed. Four channel quartz fiber optics were employed to measure two channel signals of temperature and displacement simultaneously, and the operating efficiency of this instrument was greatly improved.展开更多
Equilibrium function in the cerebellum (vestibulo-cerebellar system) can deteriorate under the influence of alcohol. In the Romberg posture, the center of gravity, which was measured every 50 ms by stabilometry, app...Equilibrium function in the cerebellum (vestibulo-cerebellar system) can deteriorate under the influence of alcohol. In the Romberg posture, the center of gravity, which was measured every 50 ms by stabilometry, appeared to shift with alcohol ingestion. In the previous study, a locus in the center of gravity (stabilogram) was converted to values of statistical indices such as area of sway, total locus length, sparse density, and locus length per unit area, although these indices could not always distinguish between the stabilograms sampled from seven healthy young males in sober and intoxicated states. This measurement was made with an AMTI force plate. In this study, "translation error" was estimated in a d-dimensional embedding space in order to compare stabilograms recorded before and after the ingestion of doubly diluted brandy in 30 s (1 ≤ d ≤ 10). The authors succeeded in validating stochastic differential equations as a mathematical model of the body sway. Although the postural control system shows different patterns in the lateral and anterior-posterior directions, the randomness in the model was preserved after alcohol intake and significantly increased in the medial/lateral direction. Visual information referred by the postural conlrol system when standing might be interfered by the effects of intoxication, which was regarded as disturbance. The possibility of detecting alcohol-ingestion-induced reduction of the equilibrium function and its recovery process are also suggested in this paper. This method is considered to be useful to diagnose the disorders of the vestibulo-cerebellar system.展开更多
A uniform optimization object function for front wheel orientation parameters of a vehicle is reported, which includes the tolerances of practical values and set values of front wheel orientation parameters under full...A uniform optimization object function for front wheel orientation parameters of a vehicle is reported, which includes the tolerances of practical values and set values of front wheel orientation parameters under full load, and the changing value of each parameter with front wheel fluctuation to build a front suspension model for optimization analysis based on the multi-body dynamic (MD) theory. The original suspension is optimized with this model, and the variation law of each parameter with front wheel fluctuation is obtained. The results of a case study demonstrate that the front wheel orientation parameters of the optimized vehicle are reasonable under typical conditions and the variation of each parameter is in an ideal range with the wheel fluctuating within 40 mm. In addition, the driving performance is improved greatly in the road test and practical use.展开更多
A microscopic diffusion-reaction modei was developed to simulate in-situ ozonation for the remediation of contaminated soil, i.e., to predict the temporal and spatial distribution of target contaminant in the subsurfa...A microscopic diffusion-reaction modei was developed to simulate in-situ ozonation for the remediation of contaminated soil, i.e., to predict the temporal and spatial distribution of target contaminant in the subsurface. The sequential strategy was employed to obtain the numerical solution of the modei using finite difference method. A non-uniform grid of discretization points was emploved to increase the accuracy of the numerical solution by means of coordinate transformation. One-dimensional column tests were conducted to verify the modei. The column was packed with simulated soils that were spiked with 2-chlorophenol. Ozone gas passed through the column at a flow rate of 100ml·min-1. The residual 2-chlorophenol content at different depths of the column was determined at fixed time intervals. Compared the experimental data with the simulated values, it was found that the mathematical modei fitted data well during most time of the experiment.展开更多
文摘The mathematical model of the motion of some plane′s flap mechanism is set up by the method of establishing mathematical model of space mechanism. When the input parameter is given, the theoretical output parameter of the flap mechanism is achieved by the model. The wear and tear volume is introduced into the mathematical model, and if the input parameter is the same, the real output parameter of the flap mechanism worn can be obtained. On the basis of this, it is able to achieve the friction and the wear reliability of the flap mechanism.
文摘An all-atom dimethyl sulfoxide (DMSO) and water model have been used for molecular dynamics simulation. The NMR and IR spectra are also performed to study the structures and interactions in the DMSO-water system. And there are traditional strong hydrogen bonds and weak C-H- ~ ~ O contacts existing in the mixtures according to the analysis of the radial distribution functions. The insight structures in the DMSO-water mixtures can be classified into different regions by the analysis of the hydrogen-bonding network. Interestingly, the molar fraction of DMSO 0.35 is found to be a special concentration by the network. It is the transitional region which is from the water rich region to the DMSO rich region. The stable aggregates of (DMSO)m'S=O…… HW-OW-(H20)n might play a key role in this region. Moreover, the simulation is compared with the chemical shifts in NMR and wavenumbers in IR with concentration dependence. And the statistical results of the average number hydrogen bonds in the MD simulations are in agreement with the experiment data in NMR and IR spectra.
基金Projects(51575289,51705270)supported by the National Natural Science Foundation of China。
文摘The thermal elasto-hydrodynamic lubrication characteristics of the internal meshing gears in a planetary gear train under vibrations were examined considering the influence of the modification coefficient and time-varying meshing stiffness.Based on dynamic theory of the gear system,a dynamic model of the planetary gear train was established.The lubrication performances of modified gear systems under vibrations and static loads were analyzed.Compared with other transmission types,the best lubrication effect could be produced by the positive transmission.A thicker lubricating oil film could be formed,and the friction coefficient and oil film flash temperature are the smallest.Increasing modification coefficient improves the lubrication performance continuously but intensifies the engage-in and tooth-change impact.For the planetary and inner gears,the increase in the modification coefficient also leads a decrease in the oil film stiffness.
基金National Natural Science Foundation of China under Grant Nos.10775097 and 10874174
文摘We propose a new two-fold integration transformation in p-q phase space∫∫^∞-∞dpdq/π e^2i(p-x)(q-y)f(p,q)≡G(x,y),which possesses some well-behaved transformation properties. We apply this transformation to the Weyl ordering of operators, especially those Q-P ordered and P-Q ordered operators.
基金supported by the National Basic Research Program of China (973 Program, 2013CB933104)the National Natural Science Foundation of China (21525313, 20973161, 21373192)+1 种基金the Fundamental Research Funds for the Central Universities (WK2060030017)Collaborative In-novation Center of Suzhou Nano Science and Technology~~
文摘The adsorption and reaction of formic acid (HCOOH) on clean and atomic oxygen‐covered Au(997) surfaces were studied by temperature‐programmed desorption/reaction spectroscopy (TPRS) and X‐ray photoelectron spectroscopy (XPS). At 105 K, HCOOH molecularly adsorbs on clean Au(997) and interacts more strongly with low‐coordinated Au atoms at (111) step sites than with those at (111) terrace sites. On an atomic oxygen‐covered Au(997) surface, HCOOH reacts with oxygen at‐oms to form HCOO and OH at 105 K. Upon subsequent heating, surface reactions occur among ad‐sorbed HCOO, OH, and atomic oxygen and produce CO2, H2O, and HCOOH between 250 and 400 K. The Au(111) steps bind surface adsorbates more strongly than the Au(111) terraces and exhibit larger barriers for HCOO(a) oxidation reactions. The surface reactions also depend on the relative coverages of co‐existing surface species. Our results elucidate the elementary surface reactions between formic acid and oxygen adatoms on Au surfaces and highlight the effects of the coordina‐tion number of the Au atoms on the Au catalysis.
基金supported by China Postdoctoral Science Foundation and National Natural Science Foundation of China under Grant No.10471139
文摘A 3 × 3 matrix spectral problem and a Liouville integrable hierarchy are constructed by designing a new subalgebra of loop algebra A^-2. Furthermore, high-order binary symmetry constraints of the corresponding hierarchy are obtained by using the binary nonlinearization method. Finally, according to another new subalgebra of loop algebra A^-2, its integrable couplings are established.
文摘Objective: The aim of the study was to study the effect of the size and location of tumors on the normal lung dose-volume parameters for lung cancer. Methods: Three spheres with diameters of 2, 3 and 4 cm made of tissue-equivalent materials used for simulating tumors were inserted into the upper lobe, middle lobe, lower lobe of the right lung, upper lobe, lower lobe of the left lung of the Rando phantom, respectively. Five-field simplified IMRT (slMRT) planning were designed. The prescribed dose was 60 Gy/2 Gy/30 f, 99% of the planning target volume received this dose. Dose-volume parameters of normal lung tissues including relative volume of lung receiving 〉 5, 10, 20, 30 and 50 Gy (V5, Vl0, V2o, V30, V50), and mean lung dose (MLD) were analyzed and compared. Results: For the dose-volume parameters, the diameter and the position of the tumor had a significant effect (P 〈 0.05). With the diameter expanding from 2 to 3 cm, the parameters associated with tumor lying in various lobes increased by a range between 3.83%-125.38%, while the parameters linked with tumors on different lobes increased by a range between 10.46%-51.46% with the diameter expanding from 3 to 4 cm. Conclusion: Location and size of sphere-like tumor have an obvious effect on dose-volume parameters. Knowing about the degree of influence will help oncologists and physicists better evaluate treatment planning, then the probability of radiation pneumonitis can be reduced.
基金supported by the National Basic Research Program of China (2009CB421505)the National Natural Science Foundation of China (41075044 and 41075079)
文摘Compared to potential temperature (θ) in the dry atmosphere and equivalent potential temperature (θc) in the saturated atmosphere, generalized potential tem- perature (θ") has already proven a better thermodynamic parameter in describing the non-uniformly saturated real atmosphere. To add otherwise absent graphic explanations, this paper first presents the physical definition of θ through a tephigram. Then, the utility of the measurement in identifying and forecasting the locations of precipita- tion maxima and heat wave areas with diagnostic com- parison studies and traditionally used thermodynamic parameters is shown.
文摘This study takes two undergraduate courses of Grade 2011 and 2012 of tourism management in an independent college as the sample, uses the questionnaires and the interviews to obtain the relevant data, analyzes the tendency of the bilingual learning of the students, and then uses the data analysis to draw the factors influencing the bilingual teaching effect. Based on the above data analysis, the paper puts forward the composition elements and the implementation path of the bilingual teaching systems of the tourism management specialty in indeoendent colleges.
文摘The paper first gives a brief overview of the use of statistical methods in sociology in order to show the continuity and importance of these methods in the development of sociology as a science. Therefore, education of sociologists requires, among other things, training in statistical methods applicable in data processing and analysis in sociological research. Then the research continues with a comparative analysis of the curricula of undergraduate academic studies of sociology, and especially the presence of statistics teaching in them, in the Republic of Serbia and the neighbouring countries. Different programs of the Department of Sociology of the Faculty of Philosophy in Novi Sad are analyzed together with the results of the students' evaluations for the academic years 2007/2008 and 2009/2010.
基金the financial supports from Natural Science Foundation of Hunan Province,China(No.2020JJ4735)Science and Technology Department of Hunan Province Tackling Key Scientific and Technological Problems and Transformation of Major Scientific and Technological Achievements,China(No.2018GK4001)the Hunan Key Laboratory for Rare Earth Functional Materials,China(No.2017TP1031).
文摘To investigate the behaviors of Cu^(2+)and Ni^(2+)with the change of conditions in Cu_(2+)−Ni_(2+)−NH_(3)−NH_(4)+−C_(2)O_(4)^(2-)−H_(2)O reaction system,mathematical models of thermodynamics based on the principle of mass conservation were established.The simulation results indicate that the precipitation of metal ions from the aqueous phase is a complicated dynamic equilibrium process,during which the coordination reactions of Cu^(2+)and Ni^(2+)with NH3 forming[Cu(NH3)n]^(2+)(n=3−5)and[Ni(NH3)m]^(2+)(m=3−6)are predominant under high pH conditions,respectively.The pH ranges for the simultaneous precipitation of Cu^(2+)and Ni^(2+)are 2.0−6.5 and 2.0−5.5 when[NH3]T equals 0.6 and 4.2 mol/L,respectively,with the prefixed[C_(2)O_(4)^(2-)]T of 0.6 mol/L.Due to the fractional precipitation of Cu^(2+)and Ni^(2+),Cu−Ni composite is obtained after the thermal decomposition of Cu−Ni oxalate complex salts prepared in a pure water system when pH>7.0.By applying the mixed solvent(water/ethanol)as the precipitation medium,the Cu−Ni alloy rods can be finally fabricated with high purity and crystallinity.
文摘Benford's law is logarithmic law for distribution of leading digits formulated by P[D=d]= log(1+1/d) where d is leading digit or group of digits. It's named by Frank Albert Benford (1938) who formulated mathematical model of this probability. Befbre him, the same observation was made by Simon Newcomb. This law has changed usual preasumption of equal probability of each digit on each position in number.The main characteristic properties of this law are base, scale, sum, inverse and product invariance. Base invariance means that logarithmic law is valid for any base. Inverse invariance means that logarithmic law for leading digits holds for inverse values in sample. Multiplication invariance means that if random variable X follows Benford's law and Y is arbitrary random variable with continuous density then XY follows Benford's law too. Sum invariance means that sums of significand are the same for any leading digit or group of digits. In this text method of testing sum invariance property is proposed.
文摘Approximate analytical solutions of the D-dimensional Klein-Gordon equation are obtained for the scalarand vector general Hulthen-type potential and position-dependent mass with any l by using the concept of supersymmetricquantum mechanics (SUSYQM).The problem is numerically discussed for some cases of parameters.
基金Projects(51904048,51922108)supported by the National Natural Science Foundation of ChinaProject(2019JJ20031)supported by the Hunan Natural Science Foundation,ChinaProject(gjj170507)supported by the Scientific Research Foundation of Jiangxi Provincial Department of Education,China。
文摘The stability constants of Sb^5+with Cl−as well as thermodynamics of the Sb−S−Cl−H2O system were calculated.The stability constants of Sb5+with Cl−were obtained by theoretical calculations of the absorbance of a Sb5+-containing solution at different Cl^−concentrations,which was detected by spectrophotometric analysis at certain wavelengths of light(380 nm).The logarithmic values versus 10 of stability constants of Sb^5+with Cl−were 1.795,3.150,4.191,4.955,5.427 and 5.511,respectively,and partly filled the data gaps in the hydrometallurgy of antimony.The presence and distribution of pentavalent antimony compounds under different conditions were analyzed based on equilibrium calculations.Thermodynamic equilibrium calculations were performed for Sb−S−Cl−H2O system,which included the complex behavior of Sb with Cl,and the equilibrium equations of related reactions in this system were integrated into the potential−pH diagram.
基金Projects(51575289,51705270)supported by the National Natural Science Foundation of China。
文摘The thermal elastohydrodynamic lubrication characteristics of a modified gear system under a dynamic load were investigated,including the influence of the modification coefficient and vibrations.Based on the dynamic theory of gear systems,a six-degree-of-freedom tribo-dynamics model was established.Thermal elastohydrodynamic lubrication characteristics of a modified gear system under vibrations and a static load were analyzed.The results showed that the positive transmission gear system exhibited the better lubrication effect compared with other transmission types.A thick lubricating oil film could be formed,and the friction coefficient between the teeth and the oil film flash temperature were the smallest.As the modification coefficient increased,the lubrication condition was continuously improved,and the scuffing load capacity was enhanced.The increment of the modification coefficient increased the meshing stiffness of the gear system but reduced the stiffness of the oil film.
文摘A novel kind of optical fiber instrument for two channel measurement of temperature and displacement was developed. Four channel quartz fiber optics were employed to measure two channel signals of temperature and displacement simultaneously, and the operating efficiency of this instrument was greatly improved.
文摘Equilibrium function in the cerebellum (vestibulo-cerebellar system) can deteriorate under the influence of alcohol. In the Romberg posture, the center of gravity, which was measured every 50 ms by stabilometry, appeared to shift with alcohol ingestion. In the previous study, a locus in the center of gravity (stabilogram) was converted to values of statistical indices such as area of sway, total locus length, sparse density, and locus length per unit area, although these indices could not always distinguish between the stabilograms sampled from seven healthy young males in sober and intoxicated states. This measurement was made with an AMTI force plate. In this study, "translation error" was estimated in a d-dimensional embedding space in order to compare stabilograms recorded before and after the ingestion of doubly diluted brandy in 30 s (1 ≤ d ≤ 10). The authors succeeded in validating stochastic differential equations as a mathematical model of the body sway. Although the postural control system shows different patterns in the lateral and anterior-posterior directions, the randomness in the model was preserved after alcohol intake and significantly increased in the medial/lateral direction. Visual information referred by the postural conlrol system when standing might be interfered by the effects of intoxication, which was regarded as disturbance. The possibility of detecting alcohol-ingestion-induced reduction of the equilibrium function and its recovery process are also suggested in this paper. This method is considered to be useful to diagnose the disorders of the vestibulo-cerebellar system.
文摘A uniform optimization object function for front wheel orientation parameters of a vehicle is reported, which includes the tolerances of practical values and set values of front wheel orientation parameters under full load, and the changing value of each parameter with front wheel fluctuation to build a front suspension model for optimization analysis based on the multi-body dynamic (MD) theory. The original suspension is optimized with this model, and the variation law of each parameter with front wheel fluctuation is obtained. The results of a case study demonstrate that the front wheel orientation parameters of the optimized vehicle are reasonable under typical conditions and the variation of each parameter is in an ideal range with the wheel fluctuating within 40 mm. In addition, the driving performance is improved greatly in the road test and practical use.
基金China Scholarship Council(No.97842039)National Natural Science Foundation of China(No.20107005)
文摘A microscopic diffusion-reaction modei was developed to simulate in-situ ozonation for the remediation of contaminated soil, i.e., to predict the temporal and spatial distribution of target contaminant in the subsurface. The sequential strategy was employed to obtain the numerical solution of the modei using finite difference method. A non-uniform grid of discretization points was emploved to increase the accuracy of the numerical solution by means of coordinate transformation. One-dimensional column tests were conducted to verify the modei. The column was packed with simulated soils that were spiked with 2-chlorophenol. Ozone gas passed through the column at a flow rate of 100ml·min-1. The residual 2-chlorophenol content at different depths of the column was determined at fixed time intervals. Compared the experimental data with the simulated values, it was found that the mathematical modei fitted data well during most time of the experiment.