Point-of-interest(POI) recommendation is a popular topic on location-based social networks(LBSNs).Geographical proximity,known as a unique feature of LBSNs,significantly affects user check-in behavior.However,most of ...Point-of-interest(POI) recommendation is a popular topic on location-based social networks(LBSNs).Geographical proximity,known as a unique feature of LBSNs,significantly affects user check-in behavior.However,most of prior studies characterize the geographical influence based on a universal or personalized distribution of geographic distance,leading to unsatisfactory recommendation results.In this paper,the personalized geographical influence in a two-dimensional geographical space is modeled using the data field method,and we propose a semi-supervised probabilistic model based on a factor graph model to integrate different factors such as the geographical influence.Moreover,a distributed learning algorithm is used to scale up our method to large-scale data sets.Experimental results based on the data sets from Foursquare and Gowalla show that our method outperforms other competing POI recommendation techniques.展开更多
A perturbative approach is used to study the AC response of nonlinear composite media, which obey a current-field relation of the form with components having nonlinear response at finite frequencies. For a sinusoidal...A perturbative approach is used to study the AC response of nonlinear composite media, which obey a current-field relation of the form with components having nonlinear response at finite frequencies. For a sinusoidal applied field, we extend the local potential in terms of sinusoidal components at fundamental frequency and high-order harmonic frequencies to treat the nonlinear composites. For nonlinear composite media with a low concentrations of spherical inclusions, we give the formulae of the nonlinear effective AC susceptibility at the third harmonic frequency.展开更多
This paper analyses the changing rule of indoor ozone concentration and its influencing factors.A formula of indoor-outdoor concentration ratio(I/O ratio) was deduced based on the indoor ozone mass-balance equation.Th...This paper analyses the changing rule of indoor ozone concentration and its influencing factors.A formula of indoor-outdoor concentration ratio(I/O ratio) was deduced based on the indoor ozone mass-balance equation.The ozone I/O ratio in different kinds of buildings was studied.Results show that I/O ratio is much related to air-exchange rate,which is well compatible with the theoretical calculation results.展开更多
The 16^th International Catalysis Congress (16th ICC) was successfully held in China in July 2016. This paper reviewed the development of catalytic science and technology of China from scratch to small then to large u...The 16^th International Catalysis Congress (16th ICC) was successfully held in China in July 2016. This paper reviewed the development of catalytic science and technology of China from scratch to small then to large under the efforts of several generations. In 1950s, catalysis discipline was first set up to train early catalytic professionals in Jilin University, Peking University and Xiamen University. Subsequently, a large research team was formed in colleges and universities, the Academy of Sciences, the Enterprise Research Institute to carry out a large number of catalytic researches. Along with the Chinese reform and opening-up, the spring of science came, and the state started to emphasize and strongly support scientific research. Chinese catalytic researchers began to enter the international catalytic academic exchange platform. Famous foreign scientists are invited to visit China and a large number of visiting scholars and foreign students have been sent to the United States, Europe and Japan, many of them have become well-known professors, and grown into catalytic academic elites. The first China-Japan-USA Symposium on Catalysis was held in Dalian in 1982, and it was expanded to become the Asian-Pacific Congress on Catalysis (APCAT), one of the three regional catalytic conferences in the world. After several generations of bidding for the organization of the International Catalytic Congress three times, China won the right to host the 16th ICC. It has effectively promoted the Chinese catalytic academic circles to the international academic ones and improved the influence of catalysis communities in China significantly. The great development in catalytic research and technology has condensed the efforts of several generations of catalysts. To make China a catalytically strong country, there is still a long way to go. We hope that the contemporary scientists can accomplish this historical task.展开更多
Combining the stability of chemical crosslinking and the processability of physical crosslinking is a well-established strategy to design new materials with desirable stimuli–responsive properties. Herein, a series o...Combining the stability of chemical crosslinking and the processability of physical crosslinking is a well-established strategy to design new materials with desirable stimuli–responsive properties. Herein, a series of azobenzenebased thermotropic liquid crystalline polyesters were synthesized by introducing mesogenic dial named 4,4＇-bis（6-hydroxyhexyloxy）azobenzene（BHHAB）, 2-phenylsuccinic acid（PSA）, and different contents of 1,2,3-propanetricarboxylic acid（PTA） as the chemical crosslinker. All these polyesters showed good thermal stability and smectic liquid crystalline phase. Wide-angel X-ray diffraction（WAXD） and the fluorescence emission spectra confirmed the existence of π–πstacking interactions as the physical crosslinking in the polymer chains, particularly at the lower content of PTA. However, when the PTA content increased, the chemical crosslinking changed the chain conformation, and thus the intensity of physical crosslinking slackened gradually. Combining the physical and chemical crosslinking, these polyesters showed the thermoplastic processability, thermal shape memory, heat-assisted healing and photoresponsive behaviors. Taking advantages of these features, these multiple stimuli–responsive polymers can bring more chances for smart materials such as soft actuator.展开更多
基金supported by National Key Basic Research Program of China(973 Program) under Grant No.2014CB340404National Natural Science Foundation of China under Grant Nos.61272111 and 61273216Youth Chenguang Project of Science and Technology of Wuhan City under Grant No. 2014070404010232
文摘Point-of-interest(POI) recommendation is a popular topic on location-based social networks(LBSNs).Geographical proximity,known as a unique feature of LBSNs,significantly affects user check-in behavior.However,most of prior studies characterize the geographical influence based on a universal or personalized distribution of geographic distance,leading to unsatisfactory recommendation results.In this paper,the personalized geographical influence in a two-dimensional geographical space is modeled using the data field method,and we propose a semi-supervised probabilistic model based on a factor graph model to integrate different factors such as the geographical influence.Moreover,a distributed learning algorithm is used to scale up our method to large-scale data sets.Experimental results based on the data sets from Foursquare and Gowalla show that our method outperforms other competing POI recommendation techniques.
文摘A perturbative approach is used to study the AC response of nonlinear composite media, which obey a current-field relation of the form with components having nonlinear response at finite frequencies. For a sinusoidal applied field, we extend the local potential in terms of sinusoidal components at fundamental frequency and high-order harmonic frequencies to treat the nonlinear composites. For nonlinear composite media with a low concentrations of spherical inclusions, we give the formulae of the nonlinear effective AC susceptibility at the third harmonic frequency.
文摘This paper analyses the changing rule of indoor ozone concentration and its influencing factors.A formula of indoor-outdoor concentration ratio(I/O ratio) was deduced based on the indoor ozone mass-balance equation.The ozone I/O ratio in different kinds of buildings was studied.Results show that I/O ratio is much related to air-exchange rate,which is well compatible with the theoretical calculation results.
文摘The 16^th International Catalysis Congress (16th ICC) was successfully held in China in July 2016. This paper reviewed the development of catalytic science and technology of China from scratch to small then to large under the efforts of several generations. In 1950s, catalysis discipline was first set up to train early catalytic professionals in Jilin University, Peking University and Xiamen University. Subsequently, a large research team was formed in colleges and universities, the Academy of Sciences, the Enterprise Research Institute to carry out a large number of catalytic researches. Along with the Chinese reform and opening-up, the spring of science came, and the state started to emphasize and strongly support scientific research. Chinese catalytic researchers began to enter the international catalytic academic exchange platform. Famous foreign scientists are invited to visit China and a large number of visiting scholars and foreign students have been sent to the United States, Europe and Japan, many of them have become well-known professors, and grown into catalytic academic elites. The first China-Japan-USA Symposium on Catalysis was held in Dalian in 1982, and it was expanded to become the Asian-Pacific Congress on Catalysis (APCAT), one of the three regional catalytic conferences in the world. After several generations of bidding for the organization of the International Catalytic Congress three times, China won the right to host the 16th ICC. It has effectively promoted the Chinese catalytic academic circles to the international academic ones and improved the influence of catalysis communities in China significantly. The great development in catalytic research and technology has condensed the efforts of several generations of catalysts. To make China a catalytically strong country, there is still a long way to go. We hope that the contemporary scientists can accomplish this historical task.
基金supported by the National Natural Science Foundation of China (51721091)the Sichuan Province Youth Science and Technology Innovation Team (2017TD0006)
文摘Combining the stability of chemical crosslinking and the processability of physical crosslinking is a well-established strategy to design new materials with desirable stimuli–responsive properties. Herein, a series of azobenzenebased thermotropic liquid crystalline polyesters were synthesized by introducing mesogenic dial named 4,4＇-bis（6-hydroxyhexyloxy）azobenzene（BHHAB）, 2-phenylsuccinic acid（PSA）, and different contents of 1,2,3-propanetricarboxylic acid（PTA） as the chemical crosslinker. All these polyesters showed good thermal stability and smectic liquid crystalline phase. Wide-angel X-ray diffraction（WAXD） and the fluorescence emission spectra confirmed the existence of π–πstacking interactions as the physical crosslinking in the polymer chains, particularly at the lower content of PTA. However, when the PTA content increased, the chemical crosslinking changed the chain conformation, and thus the intensity of physical crosslinking slackened gradually. Combining the physical and chemical crosslinking, these polyesters showed the thermoplastic processability, thermal shape memory, heat-assisted healing and photoresponsive behaviors. Taking advantages of these features, these multiple stimuli–responsive polymers can bring more chances for smart materials such as soft actuator.
