The housing vacancy rate(HVR)is an important index in assessing the healthiness of residential real estate market.In China,it is hardly to take advantage of the basic data of real estate information due to the opaque ...The housing vacancy rate(HVR)is an important index in assessing the healthiness of residential real estate market.In China,it is hardly to take advantage of the basic data of real estate information due to the opaque of those data.In this paper,the HVR is estimated to two scales.At the grid level,urban area ratio was calculated by nighttime images after eliminating outliers of nighttime images and night light intensity of non-residential pixels in mixed pixels by a proposed modified optimal threshold method,and built-up areas in each pixel were extracted from the land-cover data.Then,the HVR is calculated by comparing the light intensity of specific grid with the light intensity of full occupancy rate regions.At the administrative scale,the GCI(‘ghost city’index)is constructed by calculating the ratio of the total light radiation intensity of a city to the total construction land area of the city.The overall spatial differentiation pattern of the vacant houses in the national prefecture level administrative regions is analyzed.The following conclusions were drawn:vacant housing is rare in certain eastern coastal cities and regions in China with relatively fast economic development.Cities based on exhausted resources,some mountainous cities,and cities with relatively backward economic development more typically showed high levels of housing vacancy.The GCI of prefecture-level administrative units gradually declined from north to south,whereas the east-west distribution showed a parabolic shape.As city level decreased,the GCI registered a gradual upward trend.China’s urban housing vacancy can be divided into five categories:industry or resources driven,government planned,epitaxy expansionary,environmental constraint and speculative activate by combining the spatial distribution of housing vacancy with the factors of natural environment,social economic development level,and population density into consideration.展开更多
A series of polycrystalline samples of Co_(1-x)Zn_(x)Fe_(2)O_(4)where(x=0.1,0.2,0.3,0.4,0.5 and 0.6)were prepared by the usual ceramic technique.X-ray diffraction patterns confirmed the spinel cubic structure.The diff...A series of polycrystalline samples of Co_(1-x)Zn_(x)Fe_(2)O_(4)where(x=0.1,0.2,0.3,0.4,0.5 and 0.6)were prepared by the usual ceramic technique.X-ray diffraction patterns confirmed the spinel cubic structure.The diffusion coefficients of oxygen vacancies were estimated from dc conductivity measurements.It was noticed that the diffusion coefficient decreases with increasing Zn^(2+)concentrations.An increase of temperature increases the diffusion of lattice vacancies.The Curie temperature,lattice parameter and jump length of electrons were studied as a function of Zn^(2+)concentration.From the correlation between the ionic radius and the radii of octahedral and tetrahedral sites,the theoretical lattice parameters were calculated and suggested cation distribution for the given ferrites was determined.展开更多
基金Under the auspices of National Natural Science Foundation of China(No.2071216,41661025)Research Capacity Promotion Program for Young Teachers of Northwest Normal University(No.NWNU-LKQN-16-7)。
文摘The housing vacancy rate(HVR)is an important index in assessing the healthiness of residential real estate market.In China,it is hardly to take advantage of the basic data of real estate information due to the opaque of those data.In this paper,the HVR is estimated to two scales.At the grid level,urban area ratio was calculated by nighttime images after eliminating outliers of nighttime images and night light intensity of non-residential pixels in mixed pixels by a proposed modified optimal threshold method,and built-up areas in each pixel were extracted from the land-cover data.Then,the HVR is calculated by comparing the light intensity of specific grid with the light intensity of full occupancy rate regions.At the administrative scale,the GCI(‘ghost city’index)is constructed by calculating the ratio of the total light radiation intensity of a city to the total construction land area of the city.The overall spatial differentiation pattern of the vacant houses in the national prefecture level administrative regions is analyzed.The following conclusions were drawn:vacant housing is rare in certain eastern coastal cities and regions in China with relatively fast economic development.Cities based on exhausted resources,some mountainous cities,and cities with relatively backward economic development more typically showed high levels of housing vacancy.The GCI of prefecture-level administrative units gradually declined from north to south,whereas the east-west distribution showed a parabolic shape.As city level decreased,the GCI registered a gradual upward trend.China’s urban housing vacancy can be divided into five categories:industry or resources driven,government planned,epitaxy expansionary,environmental constraint and speculative activate by combining the spatial distribution of housing vacancy with the factors of natural environment,social economic development level,and population density into consideration.
文摘A series of polycrystalline samples of Co_(1-x)Zn_(x)Fe_(2)O_(4)where(x=0.1,0.2,0.3,0.4,0.5 and 0.6)were prepared by the usual ceramic technique.X-ray diffraction patterns confirmed the spinel cubic structure.The diffusion coefficients of oxygen vacancies were estimated from dc conductivity measurements.It was noticed that the diffusion coefficient decreases with increasing Zn^(2+)concentrations.An increase of temperature increases the diffusion of lattice vacancies.The Curie temperature,lattice parameter and jump length of electrons were studied as a function of Zn^(2+)concentration.From the correlation between the ionic radius and the radii of octahedral and tetrahedral sites,the theoretical lattice parameters were calculated and suggested cation distribution for the given ferrites was determined.
