It can be seen from the calculation that the vulnerable area along China’s coast in which the elevation is less than 5 m, is 143 900 km2, accounting for about 11. 3% of the total area of the 11 coastal provinces, mun...It can be seen from the calculation that the vulnerable area along China’s coast in which the elevation is less than 5 m, is 143 900 km2, accounting for about 11. 3% of the total area of the 11 coastal provinces, municipalities and autonomous regions. These areas are threatened to varying extent by sea level rise. According to prediction, the relative sea level rise (including global sea level rise caused by climate change and local relative as level rise caused by vertical crust movement and ground subsidence) along China’s coast will be 4～16 cm by the year 2030 with the optimum estimated value of 6～14cm. It will be 9～26 cm by the year 2050 with the optimum estimated value of 12-23 cm. And it will be 31-74 cm by the year 2100 with the optimum estimated value of 47～65 cm. The calcuation result shows that the percentage of the cost for up-grading (heightening and consolidating) sea dykes/walls in adaptation strategy in the losses of submerged areas varies from area to area: 6. 9% in the Zhujiang (Pearl) River Deta, 1. 3% ～24. 6% in the Changjiang (Yangtze) River Delta, and 0. 9%～2. 0% in the Huanghe River Delta.展开更多
[Objective] The research aimed to study the distribution characteristics of high temperature damage and its influence on the rice yield in the area along Huaihe River.[Method] The meteorological data of 10 stations in...[Objective] The research aimed to study the distribution characteristics of high temperature damage and its influence on the rice yield in the area along Huaihe River.[Method] The meteorological data of 10 stations in the area along Huaihe River during 1965-2009 and the yield data of Anhui single-season middle rice during 1967-2006 were selected.The occurrence characteristic of summer high temperature weather and the intensity of high temperature damage in the area along Huaihe River were analyzed.Based on the previous high temperature damage index of rice,Changfeng County where was the typical rice planting zone in the area along Huaihe River was as the representation,and the yield damage loss rate risk of high temperature damage in Changfeng was analyzed by combining with the historical yield data.[Result] The high temperature weather in the area along Huaihe River frequently happened.The high temperature damage presented "N" shape trend from west to east.The occurrence frequency of high temperature weather in Huainan and Bengbu where were in the middle area along Huaihe River was more and was less in Huoqiu and Shouxian where were near the south mountain area of Anhui.The occurrence time mainly focused from the middle and last dekads of July to the first dekad of August after the plum rain.At this time,it was the booting,heading and flowering periods of single-season middle rice,and the influence on the rice yield was obvious.The damage loss rate of single-season middle rice yield in Changfeng County along Huaihe River continued to increase as the increasing of high temperature damage duration.But the occurrence probability decreased.The intensity grade of high temperature damage disaster loss rate which happened frequently concentrated mainly in levels I and II.The longer the high temperature damage duration in the reproductive growth stage of rice was,the bigger the damage loss rate was.But the corresponding occurrence probability was small,and vice versa.[Conclusion] The research provided the reference for assessing the high temperature disaster risk.展开更多
For a better understanding of the air mass exchange processes between the surface and free atmos-phere in the Himalayas,a Himalayan exchange between the surface and troposphere 2007 (HEST2007) campaign was carried out...For a better understanding of the air mass exchange processes between the surface and free atmos-phere in the Himalayas,a Himalayan exchange between the surface and troposphere 2007 (HEST2007) campaign was carried out in the Rongbuk Valley,on the northern slope of Mt.Qomolangma,in June 2007.The wind,tem-perature and radiation conditions were measured during the campaign.Using these observation data,together with the National Centers for Environmental Prediction/the National Center for Atmospheric Research (NCEP/NCAR) reanalysis data,the air mass exchange between the inside of the valley and the outside of the valley is quantitatively estimated,based on a closed-valley method.The air mass is strongly injected into the Rongbuk Valley in the after-noon,which dominates the diurnal cycle,by a strong downward along-valley wind,with a maximum down-ward transfer rate of 9.4 cm s?1.The total air volume flux injected into the valley was 2.6×1011 m3 d?1 in 24 hours in June 2007,which is 15 times the total volume of the val-ley.The air mass transfer into the valley also exhibited a clear daily variation during the HEST2007 campaign,which can be affected by the synoptic situations through the adjustment of local radiation conditions.展开更多
Based on land-use database updated with the survey of 1996,2000,2004 and 2008,this paper analyzed the land-use changes in the typical transect area along National Highway 106 with the aid of GIS technology and quantit...Based on land-use database updated with the survey of 1996,2000,2004 and 2008,this paper analyzed the land-use changes in the typical transect area along National Highway 106 with the aid of GIS technology and quantitative models.The results showed that arable land had been continuously decreased from 1996 to 2008,with a loss of 65.85×103 hm2 and an average decrement of 5.49×103 hm2 per year,and the loss in northern areas was larger;garden land and woodland were gradually centralized to the predominance area with an increment of 25.73×103 hm2 and 22.37×103 hm2,respectively;residential and industrial land increased year after year,and the transportation land showed the equalized developing spatial pattern;the increment of construction land and encroachment on arable land in the area were deeply influenced by the national macroscopic land-use policies,the rapid advance of urbanization and the development level of the regional economy.Through this case study,it is suggested that differential land-use policies should be adopted to create good environmental conditions to guarantee food security and to promote the economic development.展开更多
Agriculture is related to the strategy and security of a country. Every country is very discreet about access of foreign capitals to the agricultural field. Countries along the " Belt and Road" also have imp...Agriculture is related to the strategy and security of a country. Every country is very discreet about access of foreign capitals to the agricultural field. Countries along the " Belt and Road" also have imposed restrictions on the access of foreign capitals to the agricultural field.There are restrictions on establishing agriculture-related enterprises,affiliated organizations,and branch offices. Also,there are regulations concerning the scope,proportion,performance requirement,and approval of access of foreign capitals to the agricultural field.展开更多
According to the characteristics of stone along the KKH-2 project in Pakistan, the applicability of gravel and machine-made sand for road engineering was studied. Through investigation, the types of stone along the pr...According to the characteristics of stone along the KKH-2 project in Pakistan, the applicability of gravel and machine-made sand for road engineering was studied. Through investigation, the types of stone along the project were relatively simple, and the stone materials used for road construction were mainly limestone, sandstone and pebbles, and the reserves?were?abundant. The experiment research and analyses comparisons of the parameters and road performance characteristics of natural gravel materials were carried out, and the design parameters and road performance indicators of natural grit in the current code were supplemented and adjusted to make it more suitable for Pakistan to use natural gravel materials for road construction. Thesis combines the project,?proposing that mechanism sand and natural sand mixed concrete?is?not inferior?tonatural sand mixed concrete in terms of technical performance, and the overall cost is lower than that of natural sand mixed concrete. The research results are of great significance for saving engineering construction costs, ensuring road performance and prolonging service life.展开更多
The Belt and Road Initiative requires the urgent revival of the Southern Silk Road. This means a good understanding of its rich historical connotations and its comprehensive and mutual-beneficial functions. Starting f...The Belt and Road Initiative requires the urgent revival of the Southern Silk Road. This means a good understanding of its rich historical connotations and its comprehensive and mutual-beneficial functions. Starting from a very early period, the Southern Silk Road has played an important role in the history of Yunnan and has been characterized by using cowry as money. This paper proposes the development of a new economic corridor along the Southern Silk Road from Xi'an in the north, via Chengdu and Kunming, to South Asia and Southeast Asia thus linking the Silk Road Economic Belt to the 21 st Century Maritime Silk Road. This will bring about a new phase of all-around opening-up linking domestic and overseas markets via land and sea.展开更多
In order to generalize the relativistic notion of boost to the case of non inertial particles and to general relativity, we look closer into the definition of the Lie group of Lorentz matrices and its Lie algebra and ...In order to generalize the relativistic notion of boost to the case of non inertial particles and to general relativity, we look closer into the definition of the Lie group of Lorentz matrices and its Lie algebra and we study how this group acts on the Minskowski space. We thus define the notion of tangent boost along a worldline. This very general notion gives a useful tool both in special relativity (for non inertial particles or/and for non rectilinear coordinates) and in general relativity. We also introduce a matrix of the Lie algebra which, together with the tangent boost, gives the whole dynamical description of the considered system (acceleration and Thomas rotation). After studying the properties of Lie algebra matrices and their reduced forms, we show that the Lie group of special Lorentz matrices has four one-parameter subgroups. These tools lead us to introduce the Thomas rotation in a quite general way. At the end of the paper, we present some examples using these tools and we consider the case of an electron rotating on a circular orbit around an atom nucleus. We then discuss the twin paradox and we show that when the one who made a journey into space in a high-speed rocket returns home, he is not only younger than the twin who stayed on Earth but he is also disorientated because his gyroscope has turned with respect to earth referential frame.展开更多
In this work, the extended Jacobian elliptic function expansion method is used as the first time to evaluate the exact traveling wave solutions of nonlinear evolution equations. The validity and reliability of the met...In this work, the extended Jacobian elliptic function expansion method is used as the first time to evaluate the exact traveling wave solutions of nonlinear evolution equations. The validity and reliability of the method are tested by its applications to nano-solitons of ionic waves propagation along microtubules in living cells and nano-ionic currents of MTs which play an important role in biology.展开更多
The"Ice Silk Road",ever since its proposal during the meeting between the Chinese and Russian foreign ministers in May 2017,has become an important area of bilateral cooperation.We believe that,in a broad se...The"Ice Silk Road",ever since its proposal during the meeting between the Chinese and Russian foreign ministers in May 2017,has become an important area of bilateral cooperation.We believe that,in a broad sense,the"Ice Silk Road"refers to the economic cooperation with the Arctic states;and in a narrow sense,it refers展开更多
The peripheral driver stimulating theory states that as a driver passes along a certain meridian during acupuncture;the driver provokes nerve sense devices along the meridian,resulting in the nerve impulse entering th...The peripheral driver stimulating theory states that as a driver passes along a certain meridian during acupuncture;the driver provokes nerve sense devices along the meridian,resulting in the nerve impulse entering the central nervous system.Accordingly,volunteers have reported propagated sensations along the meridians (PSM).The present study was designed to utilize a cortical somatosensory-evoked potential (CSEP) topographic map for determining whether stimulation expansion occurs in somatosensory area I when sensation was provoked in individuals with obvious PSM.The sensation was blocked by mechanical compression,and the sensation was imitated in individuals without PSM.Results revealed a red,high-potential signal in the representative area of the lower limbs in individuals with obvious PSM symptoms when the Gall Bladder Meridian (GBM) sensation passed to the head and face.This representative area was near the middle line of the CSEP topographic map,and a red,high-potential signal,which jumps over the representative area of the upper limbs,also appeared in the representative face area,which was at the external region of the CSEP topographic map.However,in individuals exhibiting no PSM,only a red high-potential signal appeared in the representative lower limb area.When Hegu (LI 4) was stimulated in individuals without PSM,an obvious evoked response appeared only in the representative upper limb area.However,when Hegu was stimulated in individuals exhibiting PSM,the response area was larger in the representative upper limb area and extended to the representative face area.When Guangming (GB 37) was stimulated in PSM individuals,the face representation response disappeared and was confined to a foot representation of the somatosensory area I when PSM was blocked by mechanical pressure.Results suggested that mechanical compression blocked PSM,and corresponding changes were exhibited in the CSEP topographic map.These results provide compelling evidence for the hypothesis that peripheral driver stimulation is the key element in producing PSM.展开更多
Most of modern tall buildings using lighter construction materials with high strength and less stiffness are more flexible, which occurs excessive wind-induced vibration, resulting in occupant discomfort and structura...Most of modern tall buildings using lighter construction materials with high strength and less stiffness are more flexible, which occurs excessive wind-induced vibration, resulting in occupant discomfort and structural unsafety. It is necessary to predict wind-induced vibration response and find out a method to mitigate such an excessive wind-induced vibration at the preliminary design stage. Recently, many studies have been conducted in using actuator control force based on the linear quadratic optimum control algorithm. It was accepted as a common knowledge that the performance of passive tuned mass damper(TMD) could increase by incorporating a feedback active control force in the design of TMD, which is called active tuned mass damper(ATMD). However, the fact that ATMD is superior to TMD to reduce wind-induced vibration of a tall building is still a question. The effectiveness of TMD for mitigating the along-wind vibration of a tall building was investigated. Optimum parameters of tuning frequency and damping ratio for TMD under a random load which has a white noise spectra were used. Fluctuating along-wind load acting on a tall building treated as a stationary Gaussian random process was simulated numerically using the along-wind load spectra. And using this simulated along-wind load, along-wind responses of a tall building with and without TMD were calculated and the effectiveness of TMD in mitigating the along-wind response of a tall building was found out.展开更多
The ensemble optimal interpolation(EnOI) is applied to the regional ocean modeling system(ROMS) with the ability to assimilate the along-track sea level anomaly(TSLA). This system is tested with an eddy-resolving syst...The ensemble optimal interpolation(EnOI) is applied to the regional ocean modeling system(ROMS) with the ability to assimilate the along-track sea level anomaly(TSLA). This system is tested with an eddy-resolving system of the South China Sea(SCS). Background errors are derived from a running seasonal ensemble to account for the seasonal variability within the SCS. A fifth-order localization function with a 250 km localization radius is chosen to reduce the negative effects of sampling errors. The data assimilation system is tested from January 2004 to December 2006. The results show that the root mean square deviation(RMSD) of the sea level anomaly decreased from 10.57 to 6.70 cm, which represents a 36.6% reduction of error. The data assimilation reduces error for temperature within the upper 800 m and for salinity within the upper 200 m, although error degrades slightly at deeper depths. Surface currents are in better agreement with trajectories of surface drifters after data assimilation. The variance of sea level improves significantly in terms of both the amplitude and position of the strong and weak variance regions after assimilating TSLA. Results with AGE error(AGE) perform better than no AGE error(NoAGE) when considering the improvements of the temperature and the salinity. Furthermore, reasons for the extremely strong variability in the northern SCS in high resolution models are investigated. The results demonstrate that the strong variability of sea level in the high resolution model is caused by an extremely strong Kuroshio intrusion. Therefore, it is demonstrated that it is necessary to assimilate the TSLA in order to better simulate the SCS with high resolution models.展开更多
In this paper, an analytical framework to evaluate the along-wind-induced dynamic responses of a transmission tower is presented. Two analytical models and a new method are developed: (1) a higher mode generalized for...In this paper, an analytical framework to evaluate the along-wind-induced dynamic responses of a transmission tower is presented. Two analytical models and a new method are developed: (1) a higher mode generalized force spectrum (GFS) model of the transmission tower is deduced; (2) an analytical model that includes the contributions of the higher modes is further derived as a rational algebraic formula to estimate the structural displacement response; and (3) a new approach, applying load with displacement (ALD) instead of force, to solve the internal force of transmission tower is given. Unlike conventional methods, the ALD method can avoid calculating equivalent static wind loads (ESWLs). Finally, a transmission tower structure is used as a numerical example to verify the feasibility and accuracy of the ALD method.展开更多
The physical investigations on the accuracy improvement to the measurement of the Earth's gravity field recovery are carried out based on the next-generation Pendulum-A/B out-of-plane twin-satellite formation in t...The physical investigations on the accuracy improvement to the measurement of the Earth's gravity field recovery are carried out based on the next-generation Pendulum-A/B out-of-plane twin-satellite formation in this paper. Firstly,the Earth's gravity field complete up to degree and order 100 is, respectively, recovered by the collinear and pendulum satellite formations using the orbital parameters of the satellite and the matching accuracies of key payloads from the twin GRACE satellites. The research results show that the accuracy of the Earth's gravity field model from the Pendulum-A/B satellite formation is about two times higher than from the collinear satellite formation, and the further improvement of the determination accuracy of the Earth's gravity field model is feasible by the next-generation Pendulum-A/B out-of-plane twin-satellite formation. Secondly, the Earth's gravity field from Pendulum-A/B complete up to degree and order 100 is accurately recovered based on the orbital parameters of the satellite(e.g., an orbital altitude of 400 km, an intersatellite range of 100 km, an orbital inclination of 89?and an orbital eccentricity of 0.001), the matching accuracies of spaceborne instruments(e.g. 10-6m in the intersatellite range, 10-3m in the orbital position, 10-6m/s in orbital velocity, and10-11m/s2 in non-conservative force), an observation time of 30 days and a sampling interval of 10 s. The measurement accuracy of the Earth's gravity field from the next-generation Pendulum-A/B out-of-plane twin-satellite formation is full of promise for being improved by about 10 times compared with that from the current GRACE satellite formation. Finally,the physical requirements for the next-generation Pendulum-A/B out-of-plane twin-satellite formation are analyzed, and it is proposed that the satellite orbital altitude be preferably designed to be close to 400±50 km and the matching precision of key sensors from the Pendulum-A/B mission be about one order of magnitude higher than from the GRACE program.展开更多
Abstract On the basis of analyzing floor strata mechanical circumstance of the roadway, the mechanical model was established. The relative displacement of roadway floor, narrow pillar floor coal mass and floor strata ...Abstract On the basis of analyzing floor strata mechanical circumstance of the roadway, the mechanical model was established. The relative displacement of roadway floor, narrow pillar floor coal mass and floor strata was calculated, the results showed that the high abutment pressure on coal mass beside the roadway was the main reason to lead to relative displacement of floor strata. And the roadway floor heave come mainly from three aspects. Firstly, the roadway floor strata is easily fractured by the stretch stress. Secondly, because the high abutment pressure is greater than the uniaxial compressive strength of floor strata, when the roadway floor strata are fractured, the coal mass floor strata at the same depth will be fractured, and broken rock will fluid into the open roadway. Thirdly, comparing with the coal mass floor, the roadway floor is relative ascending.展开更多
Focusing on the stability of surrounding rock around the roadway driving along next goaf with a narrow coal pillar, a mechanics model of the triangle block structure of main roof above the roadway is established, and ...Focusing on the stability of surrounding rock around the roadway driving along next goaf with a narrow coal pillar, a mechanics model of the triangle block structure of main roof above the roadway is established, and the sliding stability coefficient K 1 and the rotation stability coefficient K 2 are proposed to describe the stability of the triangle block structure quantitatively. The structure can keep a self stability before and after the roadway excavation, at the stage of mining induced effect, the stability of the structure is lowered, and the structure may become instability with decreasing the coal strength, increasing the mining height of working face and the mining depth.展开更多
Propagated sensation along the meridian can occur when acupoints are stimulated by acupuncture or electrical impulses.In this study,participants with notable propagated sensation along the meridian were given electro-...Propagated sensation along the meridian can occur when acupoints are stimulated by acupuncture or electrical impulses.In this study,participants with notable propagated sensation along the meridian were given electro-acupuncture at the Jianyu(LI15)acupoint of the large intestine meridian.When participants stated that the sensation reached the back of their hand,regular nervous system action discharge was examined using a physiological recording electrode placed on the superficial branch of the radial nerve.The topographical maps of brain-evoked potential in the primary cortical somatosensory area were also detected.When Guangming(GB37)acupoint in the lower limb and Hegu(LI4)acupoint in the upper limb were stimulated,subjects without propagated sensation along the meridian exhibited a high potential reaction in the corresponding area of the brain cortical somatosensory area.For subjects with a notable propagated sensation along the meridian,the reaction area was larger and extended into the face representative area.These electrophysiological measures directly prove the existence of propagated sensation along the meridian,and the peripheral stimulated site is consistent with the corresponding primary cortical somatosensory area,which presents a high potential reaction.展开更多
In view of the stress concentration problem left by the joint coal seams mining since the reservation of the coal pillar, it was proposed that non-pillar mining technology be used in Dongrong No.2 coal mine.The numeri...In view of the stress concentration problem left by the joint coal seams mining since the reservation of the coal pillar, it was proposed that non-pillar mining technology be used in Dongrong No.2 coal mine.The numerical simulation software FLAC^(2D) was used to draw the relationship between surrounding rock deformation of roadway driving along next goaf and the size of the coal pillar, so the safety and suitable position of roadway was determined.The distribution of lateral abutment pressure was measured by using the ZYJ-30 drilling stress gauge in the coal wall.The conclusions of the numerical simulation were verified.展开更多
文摘It can be seen from the calculation that the vulnerable area along China’s coast in which the elevation is less than 5 m, is 143 900 km2, accounting for about 11. 3% of the total area of the 11 coastal provinces, municipalities and autonomous regions. These areas are threatened to varying extent by sea level rise. According to prediction, the relative sea level rise (including global sea level rise caused by climate change and local relative as level rise caused by vertical crust movement and ground subsidence) along China’s coast will be 4～16 cm by the year 2030 with the optimum estimated value of 6～14cm. It will be 9～26 cm by the year 2050 with the optimum estimated value of 12-23 cm. And it will be 31-74 cm by the year 2100 with the optimum estimated value of 47～65 cm. The calcuation result shows that the percentage of the cost for up-grading (heightening and consolidating) sea dykes/walls in adaptation strategy in the losses of submerged areas varies from area to area: 6. 9% in the Zhujiang (Pearl) River Deta, 1. 3% ～24. 6% in the Changjiang (Yangtze) River Delta, and 0. 9%～2. 0% in the Huanghe River Delta.
基金Supported by Public Welfare Industry (Meteorology) Science Research Special Item (GYHY201106027)National Science and Technology Support Plan (2011BAD16B06) .
文摘[Objective] The research aimed to study the distribution characteristics of high temperature damage and its influence on the rice yield in the area along Huaihe River.[Method] The meteorological data of 10 stations in the area along Huaihe River during 1965-2009 and the yield data of Anhui single-season middle rice during 1967-2006 were selected.The occurrence characteristic of summer high temperature weather and the intensity of high temperature damage in the area along Huaihe River were analyzed.Based on the previous high temperature damage index of rice,Changfeng County where was the typical rice planting zone in the area along Huaihe River was as the representation,and the yield damage loss rate risk of high temperature damage in Changfeng was analyzed by combining with the historical yield data.[Result] The high temperature weather in the area along Huaihe River frequently happened.The high temperature damage presented "N" shape trend from west to east.The occurrence frequency of high temperature weather in Huainan and Bengbu where were in the middle area along Huaihe River was more and was less in Huoqiu and Shouxian where were near the south mountain area of Anhui.The occurrence time mainly focused from the middle and last dekads of July to the first dekad of August after the plum rain.At this time,it was the booting,heading and flowering periods of single-season middle rice,and the influence on the rice yield was obvious.The damage loss rate of single-season middle rice yield in Changfeng County along Huaihe River continued to increase as the increasing of high temperature damage duration.But the occurrence probability decreased.The intensity grade of high temperature damage disaster loss rate which happened frequently concentrated mainly in levels I and II.The longer the high temperature damage duration in the reproductive growth stage of rice was,the bigger the damage loss rate was.But the corresponding occurrence probability was small,and vice versa.[Conclusion] The research provided the reference for assessing the high temperature disaster risk.
基金financed by the National Natural Science Foundation of China (Grant No.40533018)the Ministry of Science and Technology of the People’s Republic of China (Grant No.2009CB421403)the Chinese Academy of Sciences (Grant Nos.KZCX3-SW-231 and 8-070203)
文摘For a better understanding of the air mass exchange processes between the surface and free atmos-phere in the Himalayas,a Himalayan exchange between the surface and troposphere 2007 (HEST2007) campaign was carried out in the Rongbuk Valley,on the northern slope of Mt.Qomolangma,in June 2007.The wind,tem-perature and radiation conditions were measured during the campaign.Using these observation data,together with the National Centers for Environmental Prediction/the National Center for Atmospheric Research (NCEP/NCAR) reanalysis data,the air mass exchange between the inside of the valley and the outside of the valley is quantitatively estimated,based on a closed-valley method.The air mass is strongly injected into the Rongbuk Valley in the after-noon,which dominates the diurnal cycle,by a strong downward along-valley wind,with a maximum down-ward transfer rate of 9.4 cm s?1.The total air volume flux injected into the valley was 2.6×1011 m3 d?1 in 24 hours in June 2007,which is 15 times the total volume of the val-ley.The air mass transfer into the valley also exhibited a clear daily variation during the HEST2007 campaign,which can be affected by the synoptic situations through the adjustment of local radiation conditions.
基金Supported by National Natural Science Foundation of China (40635029)China Postdoctoral Science Foundation Funded Project (20090460408)
文摘Based on land-use database updated with the survey of 1996,2000,2004 and 2008,this paper analyzed the land-use changes in the typical transect area along National Highway 106 with the aid of GIS technology and quantitative models.The results showed that arable land had been continuously decreased from 1996 to 2008,with a loss of 65.85×103 hm2 and an average decrement of 5.49×103 hm2 per year,and the loss in northern areas was larger;garden land and woodland were gradually centralized to the predominance area with an increment of 25.73×103 hm2 and 22.37×103 hm2,respectively;residential and industrial land increased year after year,and the transportation land showed the equalized developing spatial pattern;the increment of construction land and encroachment on arable land in the area were deeply influenced by the national macroscopic land-use policies,the rapid advance of urbanization and the development level of the regional economy.Through this case study,it is suggested that differential land-use policies should be adopted to create good environmental conditions to guarantee food security and to promote the economic development.
基金Supported by Young Scholar Project of Humanities and Social Science Foundation of Ministry of Education(17YJC820044)Social Science Planning PhD Project of Chongqing(2017BS39)
文摘Agriculture is related to the strategy and security of a country. Every country is very discreet about access of foreign capitals to the agricultural field. Countries along the " Belt and Road" also have imposed restrictions on the access of foreign capitals to the agricultural field.There are restrictions on establishing agriculture-related enterprises,affiliated organizations,and branch offices. Also,there are regulations concerning the scope,proportion,performance requirement,and approval of access of foreign capitals to the agricultural field.
文摘According to the characteristics of stone along the KKH-2 project in Pakistan, the applicability of gravel and machine-made sand for road engineering was studied. Through investigation, the types of stone along the project were relatively simple, and the stone materials used for road construction were mainly limestone, sandstone and pebbles, and the reserves?were?abundant. The experiment research and analyses comparisons of the parameters and road performance characteristics of natural gravel materials were carried out, and the design parameters and road performance indicators of natural grit in the current code were supplemented and adjusted to make it more suitable for Pakistan to use natural gravel materials for road construction. Thesis combines the project,?proposing that mechanism sand and natural sand mixed concrete?is?not inferior?tonatural sand mixed concrete in terms of technical performance, and the overall cost is lower than that of natural sand mixed concrete. The research results are of great significance for saving engineering construction costs, ensuring road performance and prolonging service life.
文摘The Belt and Road Initiative requires the urgent revival of the Southern Silk Road. This means a good understanding of its rich historical connotations and its comprehensive and mutual-beneficial functions. Starting from a very early period, the Southern Silk Road has played an important role in the history of Yunnan and has been characterized by using cowry as money. This paper proposes the development of a new economic corridor along the Southern Silk Road from Xi'an in the north, via Chengdu and Kunming, to South Asia and Southeast Asia thus linking the Silk Road Economic Belt to the 21 st Century Maritime Silk Road. This will bring about a new phase of all-around opening-up linking domestic and overseas markets via land and sea.
文摘In order to generalize the relativistic notion of boost to the case of non inertial particles and to general relativity, we look closer into the definition of the Lie group of Lorentz matrices and its Lie algebra and we study how this group acts on the Minskowski space. We thus define the notion of tangent boost along a worldline. This very general notion gives a useful tool both in special relativity (for non inertial particles or/and for non rectilinear coordinates) and in general relativity. We also introduce a matrix of the Lie algebra which, together with the tangent boost, gives the whole dynamical description of the considered system (acceleration and Thomas rotation). After studying the properties of Lie algebra matrices and their reduced forms, we show that the Lie group of special Lorentz matrices has four one-parameter subgroups. These tools lead us to introduce the Thomas rotation in a quite general way. At the end of the paper, we present some examples using these tools and we consider the case of an electron rotating on a circular orbit around an atom nucleus. We then discuss the twin paradox and we show that when the one who made a journey into space in a high-speed rocket returns home, he is not only younger than the twin who stayed on Earth but he is also disorientated because his gyroscope has turned with respect to earth referential frame.
文摘In this work, the extended Jacobian elliptic function expansion method is used as the first time to evaluate the exact traveling wave solutions of nonlinear evolution equations. The validity and reliability of the method are tested by its applications to nano-solitons of ionic waves propagation along microtubules in living cells and nano-ionic currents of MTs which play an important role in biology.
文摘The"Ice Silk Road",ever since its proposal during the meeting between the Chinese and Russian foreign ministers in May 2017,has become an important area of bilateral cooperation.We believe that,in a broad sense,the"Ice Silk Road"refers to the economic cooperation with the Arctic states;and in a narrow sense,it refers
基金the National Natural Science Foundation of China, No.30973720the Science Research Foundation of Ministry of Health & United Fujian Provincial Health and Education Project for Tackling the Key Research of China, No.WKJ2005-2-004
文摘The peripheral driver stimulating theory states that as a driver passes along a certain meridian during acupuncture;the driver provokes nerve sense devices along the meridian,resulting in the nerve impulse entering the central nervous system.Accordingly,volunteers have reported propagated sensations along the meridians (PSM).The present study was designed to utilize a cortical somatosensory-evoked potential (CSEP) topographic map for determining whether stimulation expansion occurs in somatosensory area I when sensation was provoked in individuals with obvious PSM.The sensation was blocked by mechanical compression,and the sensation was imitated in individuals without PSM.Results revealed a red,high-potential signal in the representative area of the lower limbs in individuals with obvious PSM symptoms when the Gall Bladder Meridian (GBM) sensation passed to the head and face.This representative area was near the middle line of the CSEP topographic map,and a red,high-potential signal,which jumps over the representative area of the upper limbs,also appeared in the representative face area,which was at the external region of the CSEP topographic map.However,in individuals exhibiting no PSM,only a red high-potential signal appeared in the representative lower limb area.When Hegu (LI 4) was stimulated in individuals without PSM,an obvious evoked response appeared only in the representative upper limb area.However,when Hegu was stimulated in individuals exhibiting PSM,the response area was larger in the representative upper limb area and extended to the representative face area.When Guangming (GB 37) was stimulated in PSM individuals,the face representation response disappeared and was confined to a foot representation of the somatosensory area I when PSM was blocked by mechanical pressure.Results suggested that mechanical compression blocked PSM,and corresponding changes were exhibited in the CSEP topographic map.These results provide compelling evidence for the hypothesis that peripheral driver stimulation is the key element in producing PSM.
基金Project(2011-0028567)supported by the National Research Foundation of Korea
文摘Most of modern tall buildings using lighter construction materials with high strength and less stiffness are more flexible, which occurs excessive wind-induced vibration, resulting in occupant discomfort and structural unsafety. It is necessary to predict wind-induced vibration response and find out a method to mitigate such an excessive wind-induced vibration at the preliminary design stage. Recently, many studies have been conducted in using actuator control force based on the linear quadratic optimum control algorithm. It was accepted as a common knowledge that the performance of passive tuned mass damper(TMD) could increase by incorporating a feedback active control force in the design of TMD, which is called active tuned mass damper(ATMD). However, the fact that ATMD is superior to TMD to reduce wind-induced vibration of a tall building is still a question. The effectiveness of TMD for mitigating the along-wind vibration of a tall building was investigated. Optimum parameters of tuning frequency and damping ratio for TMD under a random load which has a white noise spectra were used. Fluctuating along-wind load acting on a tall building treated as a stationary Gaussian random process was simulated numerically using the along-wind load spectra. And using this simulated along-wind load, along-wind responses of a tall building with and without TMD were calculated and the effectiveness of TMD in mitigating the along-wind response of a tall building was found out.
基金The Major State Basic Research Development Program of China under contract Nos 201-1CB403606 and 2011CB403500the National Natural Science Foundation of China under contract Nos 41222038,41076011and 41206023the National Marine Environmental Forecasting Center Operational Development Foundation of the State Oceanic Administration of China under contract No.2013002
文摘The ensemble optimal interpolation(EnOI) is applied to the regional ocean modeling system(ROMS) with the ability to assimilate the along-track sea level anomaly(TSLA). This system is tested with an eddy-resolving system of the South China Sea(SCS). Background errors are derived from a running seasonal ensemble to account for the seasonal variability within the SCS. A fifth-order localization function with a 250 km localization radius is chosen to reduce the negative effects of sampling errors. The data assimilation system is tested from January 2004 to December 2006. The results show that the root mean square deviation(RMSD) of the sea level anomaly decreased from 10.57 to 6.70 cm, which represents a 36.6% reduction of error. The data assimilation reduces error for temperature within the upper 800 m and for salinity within the upper 200 m, although error degrades slightly at deeper depths. Surface currents are in better agreement with trajectories of surface drifters after data assimilation. The variance of sea level improves significantly in terms of both the amplitude and position of the strong and weak variance regions after assimilating TSLA. Results with AGE error(AGE) perform better than no AGE error(NoAGE) when considering the improvements of the temperature and the salinity. Furthermore, reasons for the extremely strong variability in the northern SCS in high resolution models are investigated. The results demonstrate that the strong variability of sea level in the high resolution model is caused by an extremely strong Kuroshio intrusion. Therefore, it is demonstrated that it is necessary to assimilate the TSLA in order to better simulate the SCS with high resolution models.
基金National Natural Science Foundation of China Under Grant No.50638010Foundation of Ministry of Education for Innovation Group Under Grant No. IRT0518
文摘In this paper, an analytical framework to evaluate the along-wind-induced dynamic responses of a transmission tower is presented. Two analytical models and a new method are developed: (1) a higher mode generalized force spectrum (GFS) model of the transmission tower is deduced; (2) an analytical model that includes the contributions of the higher modes is further derived as a rational algebraic formula to estimate the structural displacement response; and (3) a new approach, applying load with displacement (ALD) instead of force, to solve the internal force of transmission tower is given. Unlike conventional methods, the ALD method can avoid calculating equivalent static wind loads (ESWLs). Finally, a transmission tower structure is used as a numerical example to verify the feasibility and accuracy of the ALD method.
基金Project supported by the Main Direction Program of Knowledge Innovation of Chinese Academy of Sciences for Distinguished Young Scholars(Grant No.KZCX2-EW-QN114)the National Natural Science Foundation of China(Grant Nos.41004006,41202094,41131067,and 11173049)+5 种基金the Merit-based Scientific Research Foundation of the State Ministry of Human Resources and Social Security of China for Returned Overseas Chinese Scholars(Grant No.2011)the Open Research Fund Program of the Key Laboratory of Geospace Environment and Geodesy,Ministry of Education,China(Grant No.11-0102)the Open Research Fund Program of the Key Laboratory of Geo-informatics of National Administration of Surveying,Mapping,and Geoinformation of China(Grant No.201322)the Open Research Fund Program of the State Key Laboratory of Geo-information Engineering,China(Grant No.SKLGIE2013M-1-5)the Main Direction Program of Institute of Geodesy and Geophysics,Chinese Academy of Sciences(Grant No.Y309451045)the Research Fund Program of State Key Laboratory of Geodesy and Earth’s Dynamics,China(Grant No.Y309491050)
文摘The physical investigations on the accuracy improvement to the measurement of the Earth's gravity field recovery are carried out based on the next-generation Pendulum-A/B out-of-plane twin-satellite formation in this paper. Firstly,the Earth's gravity field complete up to degree and order 100 is, respectively, recovered by the collinear and pendulum satellite formations using the orbital parameters of the satellite and the matching accuracies of key payloads from the twin GRACE satellites. The research results show that the accuracy of the Earth's gravity field model from the Pendulum-A/B satellite formation is about two times higher than from the collinear satellite formation, and the further improvement of the determination accuracy of the Earth's gravity field model is feasible by the next-generation Pendulum-A/B out-of-plane twin-satellite formation. Secondly, the Earth's gravity field from Pendulum-A/B complete up to degree and order 100 is accurately recovered based on the orbital parameters of the satellite(e.g., an orbital altitude of 400 km, an intersatellite range of 100 km, an orbital inclination of 89?and an orbital eccentricity of 0.001), the matching accuracies of spaceborne instruments(e.g. 10-6m in the intersatellite range, 10-3m in the orbital position, 10-6m/s in orbital velocity, and10-11m/s2 in non-conservative force), an observation time of 30 days and a sampling interval of 10 s. The measurement accuracy of the Earth's gravity field from the next-generation Pendulum-A/B out-of-plane twin-satellite formation is full of promise for being improved by about 10 times compared with that from the current GRACE satellite formation. Finally,the physical requirements for the next-generation Pendulum-A/B out-of-plane twin-satellite formation are analyzed, and it is proposed that the satellite orbital altitude be preferably designed to be close to 400±50 km and the matching precision of key sensors from the Pendulum-A/B mission be about one order of magnitude higher than from the GRACE program.
文摘Abstract On the basis of analyzing floor strata mechanical circumstance of the roadway, the mechanical model was established. The relative displacement of roadway floor, narrow pillar floor coal mass and floor strata was calculated, the results showed that the high abutment pressure on coal mass beside the roadway was the main reason to lead to relative displacement of floor strata. And the roadway floor heave come mainly from three aspects. Firstly, the roadway floor strata is easily fractured by the stretch stress. Secondly, because the high abutment pressure is greater than the uniaxial compressive strength of floor strata, when the roadway floor strata are fractured, the coal mass floor strata at the same depth will be fractured, and broken rock will fluid into the open roadway. Thirdly, comparing with the coal mass floor, the roadway floor is relative ascending.
文摘Focusing on the stability of surrounding rock around the roadway driving along next goaf with a narrow coal pillar, a mechanics model of the triangle block structure of main roof above the roadway is established, and the sliding stability coefficient K 1 and the rotation stability coefficient K 2 are proposed to describe the stability of the triangle block structure quantitatively. The structure can keep a self stability before and after the roadway excavation, at the stage of mining induced effect, the stability of the structure is lowered, and the structure may become instability with decreasing the coal strength, increasing the mining height of working face and the mining depth.
基金supported by the General Project of the National Natural Science Foundation of China,No.30973720the Natural Science Foundation of Fujian Province in China,No.2011J01192Free Topics of Fujian Provincial Science & Technology Ministry in China,No.2012fjzyyk-6
文摘Propagated sensation along the meridian can occur when acupoints are stimulated by acupuncture or electrical impulses.In this study,participants with notable propagated sensation along the meridian were given electro-acupuncture at the Jianyu(LI15)acupoint of the large intestine meridian.When participants stated that the sensation reached the back of their hand,regular nervous system action discharge was examined using a physiological recording electrode placed on the superficial branch of the radial nerve.The topographical maps of brain-evoked potential in the primary cortical somatosensory area were also detected.When Guangming(GB37)acupoint in the lower limb and Hegu(LI4)acupoint in the upper limb were stimulated,subjects without propagated sensation along the meridian exhibited a high potential reaction in the corresponding area of the brain cortical somatosensory area.For subjects with a notable propagated sensation along the meridian,the reaction area was larger and extended into the face representative area.These electrophysiological measures directly prove the existence of propagated sensation along the meridian,and the peripheral stimulated site is consistent with the corresponding primary cortical somatosensory area,which presents a high potential reaction.
文摘In view of the stress concentration problem left by the joint coal seams mining since the reservation of the coal pillar, it was proposed that non-pillar mining technology be used in Dongrong No.2 coal mine.The numerical simulation software FLAC^(2D) was used to draw the relationship between surrounding rock deformation of roadway driving along next goaf and the size of the coal pillar, so the safety and suitable position of roadway was determined.The distribution of lateral abutment pressure was measured by using the ZYJ-30 drilling stress gauge in the coal wall.The conclusions of the numerical simulation were verified.
