目的:研究辣木在全球的潜在气候适宜区划。方法:基于全球物种多样性信息数据库、实地调研、文献收集等共收集960条有效数据,综合全球气候数据库的68组生态影响因子,通过生态位最大信息熵(MaxEnt)模型研究辣木在全球和中国的潜在气候适...目的:研究辣木在全球的潜在气候适宜区划。方法:基于全球物种多样性信息数据库、实地调研、文献收集等共收集960条有效数据,综合全球气候数据库的68组生态影响因子,通过生态位最大信息熵(MaxEnt)模型研究辣木在全球和中国的潜在气候适宜区。结果:辣木在全球的气候分布概率>50%的区域有拉丁美洲、非洲中部及东部沿海区域、亚洲的东南亚地区及澳大利亚北部沿海地区;在中国范围内的气候分布概率>50%的区域为海南中南部,分布概率为30%~50%的区域主要有广东、广西、云南、福建的部分地区。结论:气候适宜性区划与《中国植物志》和《Flora of China》中描述的范围基本一致,可以为辣木在全球范围内的野生和栽培资源调查、保护和可持续发展提供参考。展开更多
In order to study the relationship between temperature & sunshine and spring-sown wheat qua lity, a spring-sown experiment with 3 wheat varieties was conducted in Rikaze, Lasa, Linzhi, Beijing and Shenyang from 1...In order to study the relationship between temperature & sunshine and spring-sown wheat qua lity, a spring-sown experiment with 3 wheat varieties was conducted in Rikaze, Lasa, Linzhi, Beijing and Shenyang from 1998 to 2001. The results indicated that significant difference on some quality characteristics of experimental wheat varieties were observed from different locations and different years. The results also showed: protein content was positively correlated with wet gluten content, falling number, the average day temperature and sunshine hours from heading to maturation; and negatively correlated with the growing days and the average diurnal temperature difference from sowing to maturation; wet gluten content was positively correlated with the average day temperature and sunshine hours during the same period. Sedimentation value and falling number were positively correlated with the average sunshine hours from sowing to maturation. The basic way of wheat production in Tibet was as follows: mainly developing medium gluten wheat varieties, suitably planting weak gluten wheat varieties, introducing some inland excellent varieties.展开更多
Energy and bandwidth are the scarce resources in ad hoc networks because most of the mobile nodes are battery-supplied and share the exclusive wireless medium. Integrating the power control into MAC protocol is a prom...Energy and bandwidth are the scarce resources in ad hoc networks because most of the mobile nodes are battery-supplied and share the exclusive wireless medium. Integrating the power control into MAC protocol is a promising technique to fully exploit these precious resources of ad hoc wireless networks. In this paper, a new intelligent power-controlled Medium Access Control (MAC) (iMAC) protocol with dynamic neighbor prediction is proposed. Through the elaborate design of the distributed transmit-receive strategy of mobile nodes, iMAC greatly outperforms the prevailing IEEE 802.11 MAC protocols in not only energy conservation but also network throughput. Using the Dynamic Neighbor Prediction (DNP), iMAC performs well in mobile scenes. To the best of our knowledge, iMAC is the first protocol that considers the performance deterioration of power-controlled MAC protocols in mobile scenes and then proposes a solution. Simulation results indicate that DNP is important and necessary for power-controlled MAC protocols in mobile ad hoc networks.展开更多
This paper proposes a double Markov model of the double continuous auction for describing intra-day price changes. The model splits intra-day price changes as the repetition of one tick price moves and assumes order a...This paper proposes a double Markov model of the double continuous auction for describing intra-day price changes. The model splits intra-day price changes as the repetition of one tick price moves and assumes order arrivals are independent Poisson random processes. The dynamic process of price formation is described by a birth-death process of the double M/M/1 server queue corresponding to the best bid/ask. The initial depths of the best bid and ask are defined as different constants depending on the last price change. Thus, the price changes in the model follow a first-order Markov process. As the initial depth of the best bid/ask is originally larger than that of the opposite side when the last price is down/up, the model may explain the negative autocorrelations of the price of the best bid/ask. The estimated parameters are based on the real tick-by-tick data of the Nikkei 225 futures listed in Osaka Stock Exchanges. The authors find the model accurately predicts the returns of Osaka Stock Exchange average.展开更多
文摘目的:研究辣木在全球的潜在气候适宜区划。方法:基于全球物种多样性信息数据库、实地调研、文献收集等共收集960条有效数据,综合全球气候数据库的68组生态影响因子,通过生态位最大信息熵(MaxEnt)模型研究辣木在全球和中国的潜在气候适宜区。结果:辣木在全球的气候分布概率>50%的区域有拉丁美洲、非洲中部及东部沿海区域、亚洲的东南亚地区及澳大利亚北部沿海地区;在中国范围内的气候分布概率>50%的区域为海南中南部,分布概率为30%~50%的区域主要有广东、广西、云南、福建的部分地区。结论:气候适宜性区划与《中国植物志》和《Flora of China》中描述的范围基本一致,可以为辣木在全球范围内的野生和栽培资源调查、保护和可持续发展提供参考。
基金This experiment was funded by the National Natural Science Foundation of China(39760039)We thank China National Bureau of Meteorology supplying relevant meteorological data.
文摘In order to study the relationship between temperature & sunshine and spring-sown wheat qua lity, a spring-sown experiment with 3 wheat varieties was conducted in Rikaze, Lasa, Linzhi, Beijing and Shenyang from 1998 to 2001. The results indicated that significant difference on some quality characteristics of experimental wheat varieties were observed from different locations and different years. The results also showed: protein content was positively correlated with wet gluten content, falling number, the average day temperature and sunshine hours from heading to maturation; and negatively correlated with the growing days and the average diurnal temperature difference from sowing to maturation; wet gluten content was positively correlated with the average day temperature and sunshine hours during the same period. Sedimentation value and falling number were positively correlated with the average sunshine hours from sowing to maturation. The basic way of wheat production in Tibet was as follows: mainly developing medium gluten wheat varieties, suitably planting weak gluten wheat varieties, introducing some inland excellent varieties.
文摘Energy and bandwidth are the scarce resources in ad hoc networks because most of the mobile nodes are battery-supplied and share the exclusive wireless medium. Integrating the power control into MAC protocol is a promising technique to fully exploit these precious resources of ad hoc wireless networks. In this paper, a new intelligent power-controlled Medium Access Control (MAC) (iMAC) protocol with dynamic neighbor prediction is proposed. Through the elaborate design of the distributed transmit-receive strategy of mobile nodes, iMAC greatly outperforms the prevailing IEEE 802.11 MAC protocols in not only energy conservation but also network throughput. Using the Dynamic Neighbor Prediction (DNP), iMAC performs well in mobile scenes. To the best of our knowledge, iMAC is the first protocol that considers the performance deterioration of power-controlled MAC protocols in mobile scenes and then proposes a solution. Simulation results indicate that DNP is important and necessary for power-controlled MAC protocols in mobile ad hoc networks.
基金supported by the National Natural Science Foundation of China under Grant Nos.71173060,71031003the Fundamental Research Funds for the Central Universities under Grant No.HIT.HSS.201120partially supported by JSPS KAKENHI under Grant No.22560059
文摘This paper proposes a double Markov model of the double continuous auction for describing intra-day price changes. The model splits intra-day price changes as the repetition of one tick price moves and assumes order arrivals are independent Poisson random processes. The dynamic process of price formation is described by a birth-death process of the double M/M/1 server queue corresponding to the best bid/ask. The initial depths of the best bid and ask are defined as different constants depending on the last price change. Thus, the price changes in the model follow a first-order Markov process. As the initial depth of the best bid/ask is originally larger than that of the opposite side when the last price is down/up, the model may explain the negative autocorrelations of the price of the best bid/ask. The estimated parameters are based on the real tick-by-tick data of the Nikkei 225 futures listed in Osaka Stock Exchanges. The authors find the model accurately predicts the returns of Osaka Stock Exchange average.
