The uncertainty in emission estimation is strongly associated with the variation in emission factor （EF）,which could be influenced by a variety of factors such as fuel properties,stove type,fire management and even ...The uncertainty in emission estimation is strongly associated with the variation in emission factor （EF）,which could be influenced by a variety of factors such as fuel properties,stove type,fire management and even methods used in measurements.The impacts of these factors are complicated and often interact with each other.Controlled burning experiments were conducted to investigate the influences of fuel mass load,air supply and burning rate on the emissions and size distributions of carbonaceous particulate matter （PM） from indoor corn straw burning in a cooking stove.The results showed that the EFs of PM （EFPM）,organic carbon （EFOC） and elemental carbon （EFEC） were independent of the fuel mass load.The differences among them under different burning rates or air supply amounts were also found to be insignificant （p 〉 0.05） in the tested circumstances.PM from the indoor corn straw burning was dominated by fine PM with diameter less than 2.1 μm,contributing 86.4%±3.9% of the total.The size distribution of PM was influenced by the burning rate and air supply conditions.On average,EF PM,EF OC and EF EC for corn straw burned in a residential cooking stove were （3.84±1.02）,（0.846±0.895） and （0.391±0.350） g/kg,respectively.EF PM,EF OC and EF EC were found to be positively correlated with each other （p 〈 0.05）,but they were not significantly correlated with the EF of co-emitted CO,suggesting that special attention should be paid to the use of CO as a surrogate for other incomplete combustion pollutants.展开更多
The marine environment, productivity and potential biotic resources in the waters of the Daya Bay were investigated by South China Sea Institute of Oceanology, Academia Sinica from 1984 to 1986. The present paper deal...The marine environment, productivity and potential biotic resources in the waters of the Daya Bay were investigated by South China Sea Institute of Oceanology, Academia Sinica from 1984 to 1986. The present paper deals mainly with the annual variation and distribution characteristics in chlorophyll a and with some of the ecological factors involved in chlorophyll distribution within the bay. Correlation models are established and discussed. The results could be helpful for further probing into ecosystem and for the exploitation-utilization of aquatic resources in this region.展开更多
A dynamic analysis approcach to investigate the state of load distribution among contact bearings of double circular are belical gears is proposed and a computer program is developed for calculating the factor of iced...A dynamic analysis approcach to investigate the state of load distribution among contact bearings of double circular are belical gears is proposed and a computer program is developed for calculating the factor of iced distribution based on the theory of W-N gears. The changing situations of load distribution among contact bearings of the gears influenced by main issues are analyzed by a series of parametric studies.展开更多
Quantitative distribution of planktonic amphipoda in the East China Sea is analyzed and the relation with environmental factors and mackerel and scad fishing grounds is studied. The result shows that the characteristi...Quantitative distribution of planktonic amphipoda in the East China Sea is analyzed and the relation with environmental factors and mackerel and scad fishing grounds is studied. The result shows that the characteristic of biomass is great seasonal and interannual variety during the passing three decades. The distribution of planktonic amphipoda basically reflects the movement, decay and intensification of the different water systems in the survey area.展开更多
To study the water quality influenced by the anthropogenic activities and its impact on the phytoplankton diversity in the surface waters of Miaodao Archipelago, the spatiotemporal variations in phytoplankton communit...To study the water quality influenced by the anthropogenic activities and its impact on the phytoplankton diversity in the surface waters of Miaodao Archipelago, the spatiotemporal variations in phytoplankton communities and the environmental properties of the surface waters surrounding the Five Southern Islands of Miaodao Archipelago were investigated, based on seasonal field survey conducted from November 2012 to August 2013. During the survey, a total of 109 phytoplankton species from 3 groups were identified in the southern waters of Miaodao Archipelago, of which 77 were diatoms, 29 were dinoflagellates, and 3 were chrysophytes. Species number was higher in winter（73）, moderate in autumn（70）, but lower in summer（31） and spring（27）. The species richness index in autumn（5.92） and winter（4.28） was higher than that in summer（2.83） and spring（1.41）.The Shannon-Wiener diversity index was high in autumn（2.82）, followed by winter（1.99） and summer（1.92）, and low in spring（0.07）. The species evenness index in autumn（0.46） and summer（0.39） was higher than that in winter（0.32） and spring（0.02）. On the basis of principal component analysis（PCA） and redundancy analysis（RDA）, we found that dissolved inorganic nitrogen（DIN） and chemical oxygen demand（COD） in spring, COD in summer, p H in autumn, and salinity and oil pollutant in winter, respectively, showed the strongest association with the distribution of phytoplankton diversity. The spatial heterogeneity of the southern waters of Miaodao Archipelago was quite obvious, and three zones, i.e., northeastern, southwestern and inter-island water area, were identified by cluster analysis（CA） based on key environmental variables.展开更多
This paper discusses the reservoir space in carbonate rocks in terms of types,combination features,distribution regularity,and controlling factors,based on core observations and tests of the North Truva Oilfield,Caspi...This paper discusses the reservoir space in carbonate rocks in terms of types,combination features,distribution regularity,and controlling factors,based on core observations and tests of the North Truva Oilfield,Caspian Basin.According to the reservoir space combinations,carbonate reservoirs can be divided into four types,i.e.,pore,fracture-pore,pore-cavity-fracture,and pore-cavity.Formation and distribution of these reservoirs is strongly controlled by deposition,diagenesis,and tectonism.In evaporated platform and restricted platform facies,the reservoirs are predominately affected by meteoric fresh water leaching in the supergene-para-syngenetic period and by uplifting and erosion in the late stage,making both platform facies contain all the above-mentioned four types of reservoirs,with various pores,such as dissolved cavities and dissolved fractures,or structural fractures occasionally in favorable structural locations.In open platform facies,the reservoirs deposited continuously in deeper water,in an environment of alternative high-energy shoals（where pore-fracture-type reservoirs are dominant） and low-energy shoals（where pore reservoirs are dominant）.展开更多
Relative navigation is a key feature in the joint tactical information distribution system（JTIDS）.A parametric message passing algorithm based on factor graph is proposed to perform relative navigation in JTIDS.Firs...Relative navigation is a key feature in the joint tactical information distribution system（JTIDS）.A parametric message passing algorithm based on factor graph is proposed to perform relative navigation in JTIDS.First of all,the joint posterior distribution of all the terminals＇ positions is represented by factor graph.Because of the nonlinearity between the positions and time-of-arrival（TOA） measurement,messages cannot be obtained in closed forms by directly using the sum-product algorithm on factor graph.To this end,the Euclidean norm is approximated by Taylor expansion.Then,all the messages on the factor graph can be derived in Gaussian forms,which enables the terminals to transmit means and covariances.Finally,the impact of major error sources on the navigation performance are evaluated by Monte Carlo simulations,e.g.,range measurement noise,priors of position uncertainty and velocity noise.Results show that the proposed algorithm outperforms the extended Kalman filter and cooperative extended Kalman filter in both static and mobile scenarios of the JTIDS.展开更多
Aim To measure the penetration of capecitabine from the plasma into tissue and to investigate the pharmacokinetics of its metabolizing into fluorouracil （5-FU） in patients with advanced breast cancer. Methods Twenty...Aim To measure the penetration of capecitabine from the plasma into tissue and to investigate the pharmacokinetics of its metabolizing into fluorouracil （5-FU） in patients with advanced breast cancer. Methods Twenty-seven patients with breast cancer received repeated doses of 1 255 mg·m^-2 of capecitabine twice daily for 7 d. Blood, tumor, and adjacent healthy tissue samples were collected. The concentrations of capecitabine and its metabolite 5-FU were determined by HPLC. The concentration-time profiles of capecitabine and 5-FU were fitted by pharmacokinetic model. The tissue distribution factors for capecitabine and 5-FU, and the AUC ratios of 5-FU to capecitabine in plasma, tumor or adjacent healthy tissue, were calculated with pharmacokinetic parameters, respectively. Results The Ka of capecitabine was 1.17 h^-1 in plasma, 0. 46 h^-1 in tumor tissue, and 0. 61 h^-1 in healthy tissue. The AUCs of capecitabine were 2. 557 1 μg·mL^-1 ·h, 1. 629 2 μg·g^-1·h and 2. 085 0 μg·g^-1· h, and T1/2 was 0. 782 3 h, 1. 528 1 h and 1. 289 6 h in plasma, tumor, and healthy tissue, respectively. The AUCs of 5-FU were 0.418 7 μg·mL^-1 h, 1.671 7 μg·g^-1·h and 1.020 8 μg·g^-1·h; the T1/2 was 0. 631 3 h ,1.204 1 h and 1.031 2 h in plasma, tumor, and healthy tissue, respectively. The tissue distribution factors of capecitabine were 0. 637 1 in tumor （AUCcap-Tumor/AUCcap-plasma） and 0. 851 4 in healthy tissue （AUCcap-HT/AUCcap-plasma . The tissue distribution factors of 5-FU were 3. 992 6 in tumor （AUC5-FU-Tumor/AUC5-FU-plasma） and 2. 438 0 in healthy tissue （AUC5-FU-HT/AUC5-FU-plasma）. The AUC ratios of 5-FU to capecitabine were 0. 1637, 1. 0261, and 0. 489 5 in plasma, tumor, and healthy tissue, respectively. Conclusion The simulation curves for the disposition of capecitabine and its metabolite 5-FU in plasma and tissue basically describe the activation process of capecitabine metabolizing to 5-FU and 5-FU elimination. There are similar distributions for capecitabine in plasma, tumor, and healthy tissue. The exposure of 5-FU in tumor was found to be 3. 992 6 times greater than that in plasma and 2. 438 0 times greater than that in healthy tissue. Capecitabine may metabolize preferentially to 5- FU in tumor tissue after oral administration.展开更多
The analytical method based on "Hertz theory on normal contact of elastic solids" and the numerical method based on finite element method (FEM) calculating the contact stress of face-gear drive with spur inv...The analytical method based on "Hertz theory on normal contact of elastic solids" and the numerical method based on finite element method (FEM) calculating the contact stress of face-gear drive with spur involute pinion were introduced, and their relative errors are below 10%, except edge contact, which turns out that these two methods can compute contact stress of face-gear drive correctly and effectively. An agreement of the localized bearing contact stress is gotten for these two methods, making sure that the calculation results of FEM are reliable. The loaded meshing simulations of multi-tooth FEM model were developed, and the determination of the transmission error and the maximal load distribution factor of face-gear drive under torques were given. A formula for the maximal load distribution factor was proposed. By introducing the maximal load distribution factor in multi-tooth contact zone, a method for calculating the maximal contact stress in multi-tooth contact can be given. Compared to FEM, the results of these formulae are proved to be reliable, and the relative errors are below 10%.展开更多
Three-level neutral point clamped(NPC)inverters have been widely applied in the high voltage and high power drive fields.The capacitance voltage balancing algorithm is a hot topic that many specialists and scholars ha...Three-level neutral point clamped(NPC)inverters have been widely applied in the high voltage and high power drive fields.The capacitance voltage balancing algorithm is a hot topic that many specialists and scholars have been working on.V arious capacitance voltage balancing strategies have been studied,in which the redundant short vectors are not fully utilized.In order to increase the capacitance voltage control effect of the short vectors,a new algorithm is proposed.展开更多
This paper proposes a novel SVPWM （space vector pulse width modulation） strategy for the three-level neutral-point-clamped voltage source inverter, based on the particular disposition of all the redundant voltage ve...This paper proposes a novel SVPWM （space vector pulse width modulation） strategy for the three-level neutral-point-clamped voltage source inverter, based on the particular disposition of all the redundant voltage vectors. The new modulation approach shows superior performance for harmonic voltage and balancing control of neutral-point potential compared to the popular eight-stage centered SVPWM. It realizes suppression of inverter neutral-point potential variation by accurately modifying redundant factor of small vectors pairs, only requiring information of DC-link capacitor voltages and three-phase load currents. This is convenient to apply and is compatible of digital computer realization. Feasibility of the proposed control approach is verified by simulation and experimental results.展开更多
Concrete precast multicell box-girder(MCB) bridges combine aesthetics with torsional stiffness perfectly.Previous analytical studies indicate that currently available specifications are unable to consider the effect o...Concrete precast multicell box-girder(MCB) bridges combine aesthetics with torsional stiffness perfectly.Previous analytical studies indicate that currently available specifications are unable to consider the effect of the twisting moment(torsional moment) on bridge actions.In straight bridges the effect of torsion is negligible and the transverse reinforced design is governed by other requirements.However,in the case of skewed bridges the effect of the twisting moment should be considered.Therefore,an in-depth study was performed on 90 concrete MCB bridges with skew angles ranging from 0° to 60°.For each girder the bridge actions were determined under the American Association of State Highway and Transportation Officials(AASHTO) live load conditions.The analytical results show that torsional stiffness and live load positions greatly affected the bridges' responses.In addition,based on a statistical analysis of the obtained results,several skew correction factors are proposed to improve the precision of the simplified Henry's method,which is widely used by bridge engineers to predict bridge actions.The relationship between the bending moment and secondary moments was also investigated and it was concluded that all secondary actions increase with an increase in skewness.展开更多
Damage detection is an important area with growing interest in mechanical and structural engineering.One of the critical issues in damage detection is how to determine indices sensitive to the structural damage and in...Damage detection is an important area with growing interest in mechanical and structural engineering.One of the critical issues in damage detection is how to determine indices sensitive to the structural damage and insensitive to the surrounding environmental variations.Current damage identification indices commonly focus on structural dynamic characteristics such as natural frequencies,mode shapes,and frequency responses.This study aimed at developing a technique based on energy Curvature Difference,power spectrum density,correlation-based index,load distribution factor,and neutral axis shift to assess the bridge deck condition.In addition to tracking energy and frequency over time using wavelet packet transform,in order to further demonstrate the feasibility and validity of the proposed technique for bridge condition assessment,experimental strain data measured from two stages of a bridge in the different intervals were used.The comparative analysis results of the bridge in first and second stage show changes in the proposed feature values.It is concluded,these changes in the values of the proposed features can be used to assess the bridge deck performance.展开更多
For a low surface barrier, the energy band, barrier height and width of the space charge region at the surface of relatively large grains of ZnO are presented analytically on condition that the electron distribution o...For a low surface barrier, the energy band, barrier height and width of the space charge region at the surface of relatively large grains of ZnO are presented analytically on condition that the electron distribution obeys the Boltzmann statistics. It is shown that the temperature in the space charge distribution factor has an important effect on the energy band, barrier height and width of the space charge region. The depletion approximation is a model in which the temperature in the space charge distribution factor is zero. Our results are better than the depletion approximation.展开更多
The plane strain asymmetrical rolling was analyzed using slab method. The contact arc was replaced by parabola, and the constant surface friction status was adopted during the analysis. The deformation area was divide...The plane strain asymmetrical rolling was analyzed using slab method. The contact arc was replaced by parabola, and the constant surface friction status was adopted during the analysis. The deformation area was divided into three zones according to the direction of the friction. Then, the three zones were studied, respectively. A rolling force model and a rolling torque model were developed based on the analysis, and they were used to analyze the influ- ence of asymmetrical rolling factors on deformation area and unit pressure if they had good precision which was determined by comparing the calculated results with the measured ones.展开更多
The purpose of this study is to analyze the climatic characteristics and long-term spatial and temporal variations of haze occurrence in China. The impact factors of haze trends are also discussed. Meteorological data...The purpose of this study is to analyze the climatic characteristics and long-term spatial and temporal variations of haze occurrence in China. The impact factors of haze trends are also discussed. Meteorological data from 1961 to 2012 and daily PM10 concentrations from2003 to 2012 were employed in this study. The results indicate that the annual-average hazy days at all stations have been increasing rapidly from 4 days in 1961 to 18 days in 2012. The maximum number of haze days occur in winter（41.1%） while the minimum occur in summer（10.4%）. During 1961-2012, the high occurrence areas of haze shifted from central to south and east regions of China. The Beijing-Tianjin-Hebei（Jing-Jin-Ji） region, Shanxi,Shaanxi, and Henan Province are the high occurrence areas for haze, while the Yangtze River Delta（YRD） and the Pearl River Delta（PRD） have become regions with high haze occurrences in the last 25 years. Temperature and pressure are positively correlated with the number of haze days. However, wind, relative humidity, precipitation, and sunshine duration are negatively correlated with the number of haze days. The key meteorological factors affecting the formation and dissipation of haze vary for high and low altitudes, and are closely related to anthropogenic activities. In recent years, anthropogenic activities have played a more important role in haze occurrences compared with meteorological factors.展开更多
The variations of grain cadmiun（Cd） concentrations, translocation factors（TFs） of Cd from roots to shoots/grains of six rice cultivars, characterized with different Cd-sensitivities in polluted soil were studied, ...The variations of grain cadmiun（Cd） concentrations, translocation factors（TFs） of Cd from roots to shoots/grains of six rice cultivars, characterized with different Cd-sensitivities in polluted soil were studied, the selected rice cultivars were Xiangzao 17（R1）, Jiayu 211（R2）, Xiangzao 42（R3）, Zhuliangyou 312（R4）, Zhuliangyou 611（R5）, and Jinyou 463（R6）, respectively. The Cd subcellular distribution and Cd binding characteristics on subcellular fractions of rice root cell wall（CW） were further investigated. The results showed that the rice grain Cd contents varied significantly, with a maximum variation of 47.0% among the cultivars, the largest grain Cd content was observed with cultivar R1（Cd-sensitivity cultivar） and the smallest with R5（Cd-tolerance cultivar）. The translocation factors of Cd from roots to shoots（TF_（shoot）） and roots to grains（TF_（grain）） varied greatly among the cultivars. In general, the TFgrain of the cultivars followed the order of R1〉R2〉R3〉R4〉 R6-R5. The Cd concentration（mg kg^（–1） FW） in the fraction of root CW, the fraction of cell wall removing pectin（CW-P） and the fraction of cell wall removing pectin and hemicellulose（CW-P-HC） of the cultivars generally followed the order of CW-P〉CW〉CWP-HC; the ratios of Cd concentration（mg kg–1 FW） in the fraction of CW-P to that of CW were mostly more than 1.10, while the ratios of Cd concentration in the fraction of CW-P-HC to that of CW were mostly less than 0.60, indicating that Cd was mainly stored in the hemicellulose of the root CW. The ratios of Cd of CW-P-HC to CW generally followed the descending order of R1~R2〉R3〉R4〉R5~R6 for the cultivars, which implied that hemicellulose is probably the main subcellular pool for transferring Cd into rice grain, and it restrains the translocation of Cd from shoot to the grain, especially for the Cd-tolerance cultivars（R5 and R6）, the compartmentation of more Cd in hemicellulose in root CW is probably one of the main mechanisms for Cd tolerance of rice cultivars.展开更多
Temperature and precipitation play an important role in the distribution of intra-annual runoff by influencing the timing and contribution of different water sources.In the northern and southern slopes of the Middle T...Temperature and precipitation play an important role in the distribution of intra-annual runoff by influencing the timing and contribution of different water sources.In the northern and southern slopes of the Middle Tianshan Mountains in China,the water sources of rivers are similar;however,the proportion and dominance of water sources contributing to runoff are different.Using the Manas River watershed in the northern slope and the Kaidu River watershed in the southern slope of the Middle Tianshan Mountains as case studies,we investigated the changes in annual runoff under climate change.A modified hydrological model was used to simulate runoff in the Kaidu River and Manas River watersheds.The results indicated that runoff was sensitive to precipitation variation in the southern slope and to temperature variation in the northern slope of the Middle Tianshan Mountains.Variations in temperature and precipitation substantially influence annual and seasonal runoff.An increase in temperature did not influence the volume of spring runoff;but it resulted in earlier spring peaks with higher levels of peak flow.Damages caused by spring peak flow from both slopes of the Middle Tianshan Mountains should be given more attention in future studies.展开更多
基金supported by the National Natural Science Foundation of China(No.41130754,41001343,41001343)the Beijing Municipal Government(No.YB20101000101)+1 种基金the Ministry of Environmental Protection(No.201209018)NIEHS(No.P42ES016465)
文摘The uncertainty in emission estimation is strongly associated with the variation in emission factor （EF）,which could be influenced by a variety of factors such as fuel properties,stove type,fire management and even methods used in measurements.The impacts of these factors are complicated and often interact with each other.Controlled burning experiments were conducted to investigate the influences of fuel mass load,air supply and burning rate on the emissions and size distributions of carbonaceous particulate matter （PM） from indoor corn straw burning in a cooking stove.The results showed that the EFs of PM （EFPM）,organic carbon （EFOC） and elemental carbon （EFEC） were independent of the fuel mass load.The differences among them under different burning rates or air supply amounts were also found to be insignificant （p 〉 0.05） in the tested circumstances.PM from the indoor corn straw burning was dominated by fine PM with diameter less than 2.1 μm,contributing 86.4%±3.9% of the total.The size distribution of PM was influenced by the burning rate and air supply conditions.On average,EF PM,EF OC and EF EC for corn straw burned in a residential cooking stove were （3.84±1.02）,（0.846±0.895） and （0.391±0.350） g/kg,respectively.EF PM,EF OC and EF EC were found to be positively correlated with each other （p 〈 0.05）,but they were not significantly correlated with the EF of co-emitted CO,suggesting that special attention should be paid to the use of CO as a surrogate for other incomplete combustion pollutants.
文摘The marine environment, productivity and potential biotic resources in the waters of the Daya Bay were investigated by South China Sea Institute of Oceanology, Academia Sinica from 1984 to 1986. The present paper deals mainly with the annual variation and distribution characteristics in chlorophyll a and with some of the ecological factors involved in chlorophyll distribution within the bay. Correlation models are established and discussed. The results could be helpful for further probing into ecosystem and for the exploitation-utilization of aquatic resources in this region.
文摘A dynamic analysis approcach to investigate the state of load distribution among contact bearings of double circular are belical gears is proposed and a computer program is developed for calculating the factor of iced distribution based on the theory of W-N gears. The changing situations of load distribution among contact bearings of the gears influenced by main issues are analyzed by a series of parametric studies.
基金This study was supported by the National Essential Foundation Study Progress Plan“973”of China under contract No.G 1999043700.
文摘Quantitative distribution of planktonic amphipoda in the East China Sea is analyzed and the relation with environmental factors and mackerel and scad fishing grounds is studied. The result shows that the characteristic of biomass is great seasonal and interannual variety during the passing three decades. The distribution of planktonic amphipoda basically reflects the movement, decay and intensification of the different water systems in the survey area.
基金The Special Project of Science and Technology Fundamental Work from the Ministry of Science and Technology of China under contract No.2012FY112500the National Natural Science Foundation of China under contract Nos 41206111 and 41206112
文摘To study the water quality influenced by the anthropogenic activities and its impact on the phytoplankton diversity in the surface waters of Miaodao Archipelago, the spatiotemporal variations in phytoplankton communities and the environmental properties of the surface waters surrounding the Five Southern Islands of Miaodao Archipelago were investigated, based on seasonal field survey conducted from November 2012 to August 2013. During the survey, a total of 109 phytoplankton species from 3 groups were identified in the southern waters of Miaodao Archipelago, of which 77 were diatoms, 29 were dinoflagellates, and 3 were chrysophytes. Species number was higher in winter（73）, moderate in autumn（70）, but lower in summer（31） and spring（27）. The species richness index in autumn（5.92） and winter（4.28） was higher than that in summer（2.83） and spring（1.41）.The Shannon-Wiener diversity index was high in autumn（2.82）, followed by winter（1.99） and summer（1.92）, and low in spring（0.07）. The species evenness index in autumn（0.46） and summer（0.39） was higher than that in winter（0.32） and spring（0.02）. On the basis of principal component analysis（PCA） and redundancy analysis（RDA）, we found that dissolved inorganic nitrogen（DIN） and chemical oxygen demand（COD） in spring, COD in summer, p H in autumn, and salinity and oil pollutant in winter, respectively, showed the strongest association with the distribution of phytoplankton diversity. The spatial heterogeneity of the southern waters of Miaodao Archipelago was quite obvious, and three zones, i.e., northeastern, southwestern and inter-island water area, were identified by cluster analysis（CA） based on key environmental variables.
基金supported by the National Major Science and Technology Project (No.2016ZX05030002)
文摘This paper discusses the reservoir space in carbonate rocks in terms of types,combination features,distribution regularity,and controlling factors,based on core observations and tests of the North Truva Oilfield,Caspian Basin.According to the reservoir space combinations,carbonate reservoirs can be divided into four types,i.e.,pore,fracture-pore,pore-cavity-fracture,and pore-cavity.Formation and distribution of these reservoirs is strongly controlled by deposition,diagenesis,and tectonism.In evaporated platform and restricted platform facies,the reservoirs are predominately affected by meteoric fresh water leaching in the supergene-para-syngenetic period and by uplifting and erosion in the late stage,making both platform facies contain all the above-mentioned four types of reservoirs,with various pores,such as dissolved cavities and dissolved fractures,or structural fractures occasionally in favorable structural locations.In open platform facies,the reservoirs deposited continuously in deeper water,in an environment of alternative high-energy shoals（where pore-fracture-type reservoirs are dominant） and low-energy shoals（where pore reservoirs are dominant）.
基金supported by the National Natural Science Foundation of China(6120118161471037+1 种基金61571041)the Foundation for the Author of National Excellent Doctoral Dissertation of China(201445)
文摘Relative navigation is a key feature in the joint tactical information distribution system（JTIDS）.A parametric message passing algorithm based on factor graph is proposed to perform relative navigation in JTIDS.First of all,the joint posterior distribution of all the terminals＇ positions is represented by factor graph.Because of the nonlinearity between the positions and time-of-arrival（TOA） measurement,messages cannot be obtained in closed forms by directly using the sum-product algorithm on factor graph.To this end,the Euclidean norm is approximated by Taylor expansion.Then,all the messages on the factor graph can be derived in Gaussian forms,which enables the terminals to transmit means and covariances.Finally,the impact of major error sources on the navigation performance are evaluated by Monte Carlo simulations,e.g.,range measurement noise,priors of position uncertainty and velocity noise.Results show that the proposed algorithm outperforms the extended Kalman filter and cooperative extended Kalman filter in both static and mobile scenarios of the JTIDS.
文摘Aim To measure the penetration of capecitabine from the plasma into tissue and to investigate the pharmacokinetics of its metabolizing into fluorouracil （5-FU） in patients with advanced breast cancer. Methods Twenty-seven patients with breast cancer received repeated doses of 1 255 mg·m^-2 of capecitabine twice daily for 7 d. Blood, tumor, and adjacent healthy tissue samples were collected. The concentrations of capecitabine and its metabolite 5-FU were determined by HPLC. The concentration-time profiles of capecitabine and 5-FU were fitted by pharmacokinetic model. The tissue distribution factors for capecitabine and 5-FU, and the AUC ratios of 5-FU to capecitabine in plasma, tumor or adjacent healthy tissue, were calculated with pharmacokinetic parameters, respectively. Results The Ka of capecitabine was 1.17 h^-1 in plasma, 0. 46 h^-1 in tumor tissue, and 0. 61 h^-1 in healthy tissue. The AUCs of capecitabine were 2. 557 1 μg·mL^-1 ·h, 1. 629 2 μg·g^-1·h and 2. 085 0 μg·g^-1· h, and T1/2 was 0. 782 3 h, 1. 528 1 h and 1. 289 6 h in plasma, tumor, and healthy tissue, respectively. The AUCs of 5-FU were 0.418 7 μg·mL^-1 h, 1.671 7 μg·g^-1·h and 1.020 8 μg·g^-1·h; the T1/2 was 0. 631 3 h ,1.204 1 h and 1.031 2 h in plasma, tumor, and healthy tissue, respectively. The tissue distribution factors of capecitabine were 0. 637 1 in tumor （AUCcap-Tumor/AUCcap-plasma） and 0. 851 4 in healthy tissue （AUCcap-HT/AUCcap-plasma . The tissue distribution factors of 5-FU were 3. 992 6 in tumor （AUC5-FU-Tumor/AUC5-FU-plasma） and 2. 438 0 in healthy tissue （AUC5-FU-HT/AUC5-FU-plasma）. The AUC ratios of 5-FU to capecitabine were 0. 1637, 1. 0261, and 0. 489 5 in plasma, tumor, and healthy tissue, respectively. Conclusion The simulation curves for the disposition of capecitabine and its metabolite 5-FU in plasma and tissue basically describe the activation process of capecitabine metabolizing to 5-FU and 5-FU elimination. There are similar distributions for capecitabine in plasma, tumor, and healthy tissue. The exposure of 5-FU in tumor was found to be 3. 992 6 times greater than that in plasma and 2. 438 0 times greater than that in healthy tissue. Capecitabine may metabolize preferentially to 5- FU in tumor tissue after oral administration.
基金Project(50875263) supported by the National Natural Science Foundation of ChinaProject(2011CB706800) supported by the National Basic Research Program of ChinaProject(2010ssxt172) supported by the Natural Science Foundation of Hunan Province,China
文摘The analytical method based on "Hertz theory on normal contact of elastic solids" and the numerical method based on finite element method (FEM) calculating the contact stress of face-gear drive with spur involute pinion were introduced, and their relative errors are below 10%, except edge contact, which turns out that these two methods can compute contact stress of face-gear drive correctly and effectively. An agreement of the localized bearing contact stress is gotten for these two methods, making sure that the calculation results of FEM are reliable. The loaded meshing simulations of multi-tooth FEM model were developed, and the determination of the transmission error and the maximal load distribution factor of face-gear drive under torques were given. A formula for the maximal load distribution factor was proposed. By introducing the maximal load distribution factor in multi-tooth contact zone, a method for calculating the maximal contact stress in multi-tooth contact can be given. Compared to FEM, the results of these formulae are proved to be reliable, and the relative errors are below 10%.
文摘Three-level neutral point clamped(NPC)inverters have been widely applied in the high voltage and high power drive fields.The capacitance voltage balancing algorithm is a hot topic that many specialists and scholars have been working on.V arious capacitance voltage balancing strategies have been studied,in which the redundant short vectors are not fully utilized.In order to increase the capacitance voltage control effect of the short vectors,a new algorithm is proposed.
文摘This paper proposes a novel SVPWM （space vector pulse width modulation） strategy for the three-level neutral-point-clamped voltage source inverter, based on the particular disposition of all the redundant voltage vectors. The new modulation approach shows superior performance for harmonic voltage and balancing control of neutral-point potential compared to the popular eight-stage centered SVPWM. It realizes suppression of inverter neutral-point potential variation by accurately modifying redundant factor of small vectors pairs, only requiring information of DC-link capacitor voltages and three-phase load currents. This is convenient to apply and is compatible of digital computer realization. Feasibility of the proposed control approach is verified by simulation and experimental results.
文摘Concrete precast multicell box-girder(MCB) bridges combine aesthetics with torsional stiffness perfectly.Previous analytical studies indicate that currently available specifications are unable to consider the effect of the twisting moment(torsional moment) on bridge actions.In straight bridges the effect of torsion is negligible and the transverse reinforced design is governed by other requirements.However,in the case of skewed bridges the effect of the twisting moment should be considered.Therefore,an in-depth study was performed on 90 concrete MCB bridges with skew angles ranging from 0° to 60°.For each girder the bridge actions were determined under the American Association of State Highway and Transportation Officials(AASHTO) live load conditions.The analytical results show that torsional stiffness and live load positions greatly affected the bridges' responses.In addition,based on a statistical analysis of the obtained results,several skew correction factors are proposed to improve the precision of the simplified Henry's method,which is widely used by bridge engineers to predict bridge actions.The relationship between the bending moment and secondary moments was also investigated and it was concluded that all secondary actions increase with an increase in skewness.
文摘Damage detection is an important area with growing interest in mechanical and structural engineering.One of the critical issues in damage detection is how to determine indices sensitive to the structural damage and insensitive to the surrounding environmental variations.Current damage identification indices commonly focus on structural dynamic characteristics such as natural frequencies,mode shapes,and frequency responses.This study aimed at developing a technique based on energy Curvature Difference,power spectrum density,correlation-based index,load distribution factor,and neutral axis shift to assess the bridge deck condition.In addition to tracking energy and frequency over time using wavelet packet transform,in order to further demonstrate the feasibility and validity of the proposed technique for bridge condition assessment,experimental strain data measured from two stages of a bridge in the different intervals were used.The comparative analysis results of the bridge in first and second stage show changes in the proposed feature values.It is concluded,these changes in the values of the proposed features can be used to assess the bridge deck performance.
文摘For a low surface barrier, the energy band, barrier height and width of the space charge region at the surface of relatively large grains of ZnO are presented analytically on condition that the electron distribution obeys the Boltzmann statistics. It is shown that the temperature in the space charge distribution factor has an important effect on the energy band, barrier height and width of the space charge region. The depletion approximation is a model in which the temperature in the space charge distribution factor is zero. Our results are better than the depletion approximation.
基金Item Sponsored by National Natural Science Foundation of China (50104006)National Key Technology Research and Development Program of China(2006BAE03A08)
文摘The plane strain asymmetrical rolling was analyzed using slab method. The contact arc was replaced by parabola, and the constant surface friction status was adopted during the analysis. The deformation area was divided into three zones according to the direction of the friction. Then, the three zones were studied, respectively. A rolling force model and a rolling torque model were developed based on the analysis, and they were used to analyze the influ- ence of asymmetrical rolling factors on deformation area and unit pressure if they had good precision which was determined by comparing the calculated results with the measured ones.
基金supported by the CMA’s special Funds for climate change(No.CCSF201439)the CMA’s special Funds for key technology(No.CMAGJ2015M79)the MEP’s Special Funds for Research on Public Welfares(No.201409002)
文摘The purpose of this study is to analyze the climatic characteristics and long-term spatial and temporal variations of haze occurrence in China. The impact factors of haze trends are also discussed. Meteorological data from 1961 to 2012 and daily PM10 concentrations from2003 to 2012 were employed in this study. The results indicate that the annual-average hazy days at all stations have been increasing rapidly from 4 days in 1961 to 18 days in 2012. The maximum number of haze days occur in winter（41.1%） while the minimum occur in summer（10.4%）. During 1961-2012, the high occurrence areas of haze shifted from central to south and east regions of China. The Beijing-Tianjin-Hebei（Jing-Jin-Ji） region, Shanxi,Shaanxi, and Henan Province are the high occurrence areas for haze, while the Yangtze River Delta（YRD） and the Pearl River Delta（PRD） have become regions with high haze occurrences in the last 25 years. Temperature and pressure are positively correlated with the number of haze days. However, wind, relative humidity, precipitation, and sunshine duration are negatively correlated with the number of haze days. The key meteorological factors affecting the formation and dissipation of haze vary for high and low altitudes, and are closely related to anthropogenic activities. In recent years, anthropogenic activities have played a more important role in haze occurrences compared with meteorological factors.
基金financially supported by the National Natural Science Foundation of China(41271490,21077131)the National Key Research and Development Program of China(2016YFD0800707)
文摘The variations of grain cadmiun（Cd） concentrations, translocation factors（TFs） of Cd from roots to shoots/grains of six rice cultivars, characterized with different Cd-sensitivities in polluted soil were studied, the selected rice cultivars were Xiangzao 17（R1）, Jiayu 211（R2）, Xiangzao 42（R3）, Zhuliangyou 312（R4）, Zhuliangyou 611（R5）, and Jinyou 463（R6）, respectively. The Cd subcellular distribution and Cd binding characteristics on subcellular fractions of rice root cell wall（CW） were further investigated. The results showed that the rice grain Cd contents varied significantly, with a maximum variation of 47.0% among the cultivars, the largest grain Cd content was observed with cultivar R1（Cd-sensitivity cultivar） and the smallest with R5（Cd-tolerance cultivar）. The translocation factors of Cd from roots to shoots（TF_（shoot）） and roots to grains（TF_（grain）） varied greatly among the cultivars. In general, the TFgrain of the cultivars followed the order of R1〉R2〉R3〉R4〉 R6-R5. The Cd concentration（mg kg^（–1） FW） in the fraction of root CW, the fraction of cell wall removing pectin（CW-P） and the fraction of cell wall removing pectin and hemicellulose（CW-P-HC） of the cultivars generally followed the order of CW-P〉CW〉CWP-HC; the ratios of Cd concentration（mg kg–1 FW） in the fraction of CW-P to that of CW were mostly more than 1.10, while the ratios of Cd concentration in the fraction of CW-P-HC to that of CW were mostly less than 0.60, indicating that Cd was mainly stored in the hemicellulose of the root CW. The ratios of Cd of CW-P-HC to CW generally followed the descending order of R1~R2〉R3〉R4〉R5~R6 for the cultivars, which implied that hemicellulose is probably the main subcellular pool for transferring Cd into rice grain, and it restrains the translocation of Cd from shoot to the grain, especially for the Cd-tolerance cultivars（R5 and R6）, the compartmentation of more Cd in hemicellulose in root CW is probably one of the main mechanisms for Cd tolerance of rice cultivars.
基金funded by the National Basic Research Program of China (2012CB956204)the Special Funds for the Key Laboratory of the Xinjiang Uygur Autonomous Region (2014KL015)the Key Deployment Project of Chinese Academy of Sciences (KZZD-EW-12-2)
文摘Temperature and precipitation play an important role in the distribution of intra-annual runoff by influencing the timing and contribution of different water sources.In the northern and southern slopes of the Middle Tianshan Mountains in China,the water sources of rivers are similar;however,the proportion and dominance of water sources contributing to runoff are different.Using the Manas River watershed in the northern slope and the Kaidu River watershed in the southern slope of the Middle Tianshan Mountains as case studies,we investigated the changes in annual runoff under climate change.A modified hydrological model was used to simulate runoff in the Kaidu River and Manas River watersheds.The results indicated that runoff was sensitive to precipitation variation in the southern slope and to temperature variation in the northern slope of the Middle Tianshan Mountains.Variations in temperature and precipitation substantially influence annual and seasonal runoff.An increase in temperature did not influence the volume of spring runoff;but it resulted in earlier spring peaks with higher levels of peak flow.Damages caused by spring peak flow from both slopes of the Middle Tianshan Mountains should be given more attention in future studies.
