Li2O-Al2O3-SiO2 glass prepared from traditional melting and cooling process was investigated.The surface characteristic of LAS glass was studied by simulating tin bath with different temperature and time,and the effec...Li2O-Al2O3-SiO2 glass prepared from traditional melting and cooling process was investigated.The surface characteristic of LAS glass was studied by simulating tin bath with different temperature and time,and the effect of surface tension/viscosity ratio on flatting time was analyzed.The results demonstrated that LAS glass can polish effectively when polishing at 1 300 ℃ for 8 min,and the optimum flatting and polishing temperature was 1 250-1 300 ℃.展开更多
This paper presents an investigation of the seismic behavior of reinforced concrete(RC)structures in which shear walls are the main lateral load-resisting elements and the participation of flat slab floor systems is n...This paper presents an investigation of the seismic behavior of reinforced concrete(RC)structures in which shear walls are the main lateral load-resisting elements and the participation of flat slab floor systems is not considered in the seismic design procedure.In this regard,the behavior of six prototype structures(with different heights and plan layouts)is investigated through nonlinear static and time history analyses,implemented in the OpenSees platform.The results of the analyses are presented in terms of the behavior of the slab-column connections and their mode of failure at different loading stages.Moreover,the global response of the buildings is discussed in terms of some parameters,such as lateral overstrength due to the gravity flat slab-column frames.According to the nonlinear static analyses,in structures in which the slab-column connections were designed only for gravity loads,the slab-column connections exhibited a punching mode of failure even in the early stages of loading.However,the punching failure was eliminated in structures in which a minimum transverse reinforcement recommended in ACI 318(2019)was provided in the slabs at joint regions.Furthermore,despite neglecting the contribution of gravity flat slab-column frames in the lateral load resistance of the structures,a relatively significant overstrength was imposed on the structures by the gravity frames.展开更多
The relativity of cosmic time is developed within the framework of Cosmological Relativity in five dimensions of space, time and velocity. A general linearized metric element is defined to have the form , where the co...The relativity of cosmic time is developed within the framework of Cosmological Relativity in five dimensions of space, time and velocity. A general linearized metric element is defined to have the form , where the coordinates are time , radial distance for spatials x, y and z, and velocity v, with c the speed of light in vacuum and t the Hubble-Carmeli time constant. The metric is accurate to first order in and v/c . The fields and are general functions of the coordinates. By showing that =, a metric of the form is obtained from the general metric, implying that the universe is flat. For cosmological redshift z, the luminosity distance relation is used to fit combined distance moduli from Type 1a supernovae up to z is obtained for the matter density parameter at the present epoch. Assuming a baryon density of , a rest mass energy of (9.79+ 0.47) GeV is predicted for the anti-baryonic and the particles which decay from a hypothetical particle. The cosmic aging function makes good fits to light curve data from two reports of Type 1a supernovae and in fitting to simulated quasar like light curve power spectra separated by redshift . We determine the multipole of the first acoustic peak of the Cosmic Microwave Background radiation anisotropy to be and a sound horizon of on today’s sky.展开更多
Genetic algorithms offer very good performances for solving large optimization problems, especially in the domain of error-correcting codes. However, they have a major drawback related to the time complexity and memor...Genetic algorithms offer very good performances for solving large optimization problems, especially in the domain of error-correcting codes. However, they have a major drawback related to the time complexity and memory occupation when running on a uniprocessor computer. This paper proposes a parallel decoder for linear block codes, using parallel genetic algorithms (PGA). The good performance and time complexity are confirmed by theoretical study and by simulations on BCH(63,30,14) codes over both AWGN and flat Rayleigh fading channels. The simulation results show that the coding gain between parallel and single genetic algorithm is about 0.7 dB at BER = 10﹣5 with only 4 processors.展开更多
General Relativity implies an expanding Universe from a singularity, the so-called Big Bang. The rate of expansion is the Hubble constant. There are two major ways of measuring the expansion of the Universe: through t...General Relativity implies an expanding Universe from a singularity, the so-called Big Bang. The rate of expansion is the Hubble constant. There are two major ways of measuring the expansion of the Universe: through the cosmic distance ladder and through looking at the signals originated from the beginning of the Universe. These two methods give quite different results for the Hubble constant. Hence, the Universe doesn’t expand. The solution to this problem is the theory of gravitation in flat space-time where space isn’t expanding. All the results of gravitation for weak fields of this theory agree with those of General Relativity to measurable accuracy whereas at the beginning of the Universe the results of both theories are quite different, i.e. no singularity by gravitation in flat space-time and non-expanding universe, and a Big Bang (singularity) by General Relativity.展开更多
In this work,we have searched for quasi-periodic oscillations(QPOs)in the 15 GHz light curve of the FSRQ PKS J0805-0111 monitored by the Owens Valley Radio Observatory(OVRO)40 m telescope during the period from 2008 J...In this work,we have searched for quasi-periodic oscillations(QPOs)in the 15 GHz light curve of the FSRQ PKS J0805-0111 monitored by the Owens Valley Radio Observatory(OVRO)40 m telescope during the period from 2008 January 9 to 2019 May 9,using the weighted wavelet Z-transform(WWZ)and the Lomb-Scargle Periodogram(LSP)techniques.This is the first time to search for a periodic radio signal in the FSRQ PKS J0805-0111 by these two methods.Both methods consistently reveal a repeating signal with a periodicity of 3.38±0.8 yr(>99.7%confidence level).In order to determine the significance of the periods,the false alarm probability method was applied,and a large number of Monte Carlo simulations were performed.As possible explanations,we discuss a number of scenarios including the thermal instability of thin disks scenario,the spiral jet scenario and the binary supermassive black hole scenario.We expect that the binary black hole scenario,where the QPO is caused by the precession of binary black holes,is the most likely explanation.FSRQ PKS J0805-0111 thus could be a good binary black hole candidate.In the binary black hole scenario,the distance between the primary black hole and the secondary black hole is about 1.71×10^(16) cm.展开更多
The quantum electrodynamics(QED)in a spatially flat(1+3)-dimensional Friedmann-Lema?tre-Robertson-Walker(FLRW)space-time with a Milne-type scale factor is outlined focusing on the amplitudes of the allowed processes i...The quantum electrodynamics(QED)in a spatially flat(1+3)-dimensional Friedmann-Lema?tre-Robertson-Walker(FLRW)space-time with a Milne-type scale factor is outlined focusing on the amplitudes of the allowed processes in the first order perturbations.The definition of the transition rates is reconsidered such that an appropriate angular behavior of the probability for creation of an electron-positron pair from a photon is obtained,which has a similar rate as the creation of a photon and an electron-positron pair from vacuum.It is shown that these processes are allowed only in the first order perturbations,since the photon emission or absorption by an electron or positron are forbidden.展开更多
基金Funded partly by the National Key Technology R&D Program in the 11th Five Year Plan of China(No. 2006BAJ02B00)Natural Science Foundation of Hubei Province (No.2008CDA037)
文摘Li2O-Al2O3-SiO2 glass prepared from traditional melting and cooling process was investigated.The surface characteristic of LAS glass was studied by simulating tin bath with different temperature and time,and the effect of surface tension/viscosity ratio on flatting time was analyzed.The results demonstrated that LAS glass can polish effectively when polishing at 1 300 ℃ for 8 min,and the optimum flatting and polishing temperature was 1 250-1 300 ℃.
文摘This paper presents an investigation of the seismic behavior of reinforced concrete(RC)structures in which shear walls are the main lateral load-resisting elements and the participation of flat slab floor systems is not considered in the seismic design procedure.In this regard,the behavior of six prototype structures(with different heights and plan layouts)is investigated through nonlinear static and time history analyses,implemented in the OpenSees platform.The results of the analyses are presented in terms of the behavior of the slab-column connections and their mode of failure at different loading stages.Moreover,the global response of the buildings is discussed in terms of some parameters,such as lateral overstrength due to the gravity flat slab-column frames.According to the nonlinear static analyses,in structures in which the slab-column connections were designed only for gravity loads,the slab-column connections exhibited a punching mode of failure even in the early stages of loading.However,the punching failure was eliminated in structures in which a minimum transverse reinforcement recommended in ACI 318(2019)was provided in the slabs at joint regions.Furthermore,despite neglecting the contribution of gravity flat slab-column frames in the lateral load resistance of the structures,a relatively significant overstrength was imposed on the structures by the gravity frames.
文摘The relativity of cosmic time is developed within the framework of Cosmological Relativity in five dimensions of space, time and velocity. A general linearized metric element is defined to have the form , where the coordinates are time , radial distance for spatials x, y and z, and velocity v, with c the speed of light in vacuum and t the Hubble-Carmeli time constant. The metric is accurate to first order in and v/c . The fields and are general functions of the coordinates. By showing that =, a metric of the form is obtained from the general metric, implying that the universe is flat. For cosmological redshift z, the luminosity distance relation is used to fit combined distance moduli from Type 1a supernovae up to z is obtained for the matter density parameter at the present epoch. Assuming a baryon density of , a rest mass energy of (9.79+ 0.47) GeV is predicted for the anti-baryonic and the particles which decay from a hypothetical particle. The cosmic aging function makes good fits to light curve data from two reports of Type 1a supernovae and in fitting to simulated quasar like light curve power spectra separated by redshift . We determine the multipole of the first acoustic peak of the Cosmic Microwave Background radiation anisotropy to be and a sound horizon of on today’s sky.
文摘Genetic algorithms offer very good performances for solving large optimization problems, especially in the domain of error-correcting codes. However, they have a major drawback related to the time complexity and memory occupation when running on a uniprocessor computer. This paper proposes a parallel decoder for linear block codes, using parallel genetic algorithms (PGA). The good performance and time complexity are confirmed by theoretical study and by simulations on BCH(63,30,14) codes over both AWGN and flat Rayleigh fading channels. The simulation results show that the coding gain between parallel and single genetic algorithm is about 0.7 dB at BER = 10﹣5 with only 4 processors.
文摘General Relativity implies an expanding Universe from a singularity, the so-called Big Bang. The rate of expansion is the Hubble constant. There are two major ways of measuring the expansion of the Universe: through the cosmic distance ladder and through looking at the signals originated from the beginning of the Universe. These two methods give quite different results for the Hubble constant. Hence, the Universe doesn’t expand. The solution to this problem is the theory of gravitation in flat space-time where space isn’t expanding. All the results of gravitation for weak fields of this theory agree with those of General Relativity to measurable accuracy whereas at the beginning of the Universe the results of both theories are quite different, i.e. no singularity by gravitation in flat space-time and non-expanding universe, and a Big Bang (singularity) by General Relativity.
基金supported by the National Natural Science Foundation of China(Grant No.11663009)the High-Energy Astrophysics Science and Technology Innovation Team of Yunnan Higher School+1 种基金the OVRO40-m monitoring program(Fan&Wu 2018)which is supported in part by NASA grants NNX08AW31GNNX11A043G and NNX14AQ89G,and NSF grants AST-0808050 and AST-1109911。
文摘In this work,we have searched for quasi-periodic oscillations(QPOs)in the 15 GHz light curve of the FSRQ PKS J0805-0111 monitored by the Owens Valley Radio Observatory(OVRO)40 m telescope during the period from 2008 January 9 to 2019 May 9,using the weighted wavelet Z-transform(WWZ)and the Lomb-Scargle Periodogram(LSP)techniques.This is the first time to search for a periodic radio signal in the FSRQ PKS J0805-0111 by these two methods.Both methods consistently reveal a repeating signal with a periodicity of 3.38±0.8 yr(>99.7%confidence level).In order to determine the significance of the periods,the false alarm probability method was applied,and a large number of Monte Carlo simulations were performed.As possible explanations,we discuss a number of scenarios including the thermal instability of thin disks scenario,the spiral jet scenario and the binary supermassive black hole scenario.We expect that the binary black hole scenario,where the QPO is caused by the precession of binary black holes,is the most likely explanation.FSRQ PKS J0805-0111 thus could be a good binary black hole candidate.In the binary black hole scenario,the distance between the primary black hole and the secondary black hole is about 1.71×10^(16) cm.
文摘The quantum electrodynamics(QED)in a spatially flat(1+3)-dimensional Friedmann-Lema?tre-Robertson-Walker(FLRW)space-time with a Milne-type scale factor is outlined focusing on the amplitudes of the allowed processes in the first order perturbations.The definition of the transition rates is reconsidered such that an appropriate angular behavior of the probability for creation of an electron-positron pair from a photon is obtained,which has a similar rate as the creation of a photon and an electron-positron pair from vacuum.It is shown that these processes are allowed only in the first order perturbations,since the photon emission or absorption by an electron or positron are forbidden.
