Background,aim,and scope Soil saturated hydraulic conductivity(K_(s))is a key parameter in the hydrological cycle of soil;however,we have very limited understanding of K_(s) characteristics and the factors that inf lu...Background,aim,and scope Soil saturated hydraulic conductivity(K_(s))is a key parameter in the hydrological cycle of soil;however,we have very limited understanding of K_(s) characteristics and the factors that inf luence this key parameter in the Mu Us sandy land(MUSL).Quantifying the impact of changes in land use in the Mu Us sandy land on K_(s) will provide a key foundation for understanding the regional water cycle,but will also provide a scientific basis for the governance of the MUSL.Materials and methods In this study,we determined K_(s) and the basic physical and chemical properties of soil(i.e.,organic matter,bulk density,and soil particle composition)within the first 100 cm layer of four different land use patterns(farmland,tree,shrub,and grassland)in the MUSL.The vertical variation of K_(s) and the factors that influence this key parameter were analyzed and a transfer function for estimating K_(s) was established based on a multiple stepwise regression model.Results The K_(s) of farmland,tree,and shrub increased gradually with soil depth while that of grassland remained unchanged.The K_(s) of the four patterns of land use were moderately variable;mean K_(s)values were ranked as follows:grassland(1.38 mm·min^(-1))<tree(1.76 mm·min^(-1))<farmland(1.82 mm·min^(-1))<shrub(3.30 mm·min^(-1)).The correlation between K_(s) and organic matter,bulk density,and soil particle composition,varied across different land use patterns.A multiple stepwise regression model showed that silt,coarse sand,bulk density,and organic matter,were key predictive factors for the K_(s) of farmland,tree,shrub,and grassland,in the MUSL.Discussion The vertical distribution trend for K_(s) in farmland is known to be predominantly influenced by cultivation,fertilization,and other factors.The general aim is to improve the water-holding capacity of shallow soil on farmland(0-30 cm in depth)to conserve water and nutrients;research has shown that the K_(s) of farmland increases with soil depth.The root growth of tree and shrub in sandy land exerts mechanical force on the soil due to biophysical processes involving rhizospheres,thus leading to a significant change in K_(s).We found that shallow high-density fine roots increased the volume of soil pores and eliminated large pores,thus resulting in a reduction in shallow K_(s).Therefore,the K_(s) of tree and shrub increased with soil depth.Analysis also showed that the K_(s) of grassland did not change significantly and exhibited the lowest mean value when compared to other land use patterns.This finding was predominantly due to the shallow root system of grasslands and because this land use pattern is not subject to human activities such as cultivation and fertilization;consequently,there was no significant change in K_(s) with depth;grassland also had the lowest mean K_(s).We also established a transfer function for K_(s) for different land use patterns in the MUSL.However,the predictive factors for K_(s) in different land use patterns are known to be affected by soil cultivation methods,vegetation restoration modes,the distribution of soil moisture,and other factors,thus resulting in key differences.Therefore,when using the transfer function to predict K_(s) in other areas,it will be necessary to perform parameter calibration and further verification.Conclusions In the MUSL,the K_(s) of farmland,tree,and shrub gradually increased with soil depth;however,the K_(s) of grassland showed no significant variation in terms of vertical distribution.The mean K_(s) values of different land use patterns were ranked as follows:shrub>farmland>tree>grassland;all land use patterns showed moderate levels of variability.The K_(s) for different land use patterns exhibited differing degrees of correlation with soil physical and chemical properties;of these,clay,silt,sand,bulk density,and organic matter,were identified as important variables for predicting K_(s) in farmland,tree,shrub,and grassland,respectively.Recommendations and perspectives In this study,we used a stepwise multiple regression model to establish a transfer function prediction model for K_(s) for different land use patterns;this model possessed high estimation accuracy.The ability to predict K_(s) in the MUSL is very important in terms of the conservation of water and nutrients.展开更多
To increase the performance of bulk data transfer mission with ultra-long TCP （ transmission control protocol） connection in high-energy physics experiments, a series of experiments were conducted to explore the way...To increase the performance of bulk data transfer mission with ultra-long TCP （ transmission control protocol） connection in high-energy physics experiments, a series of experiments were conducted to explore the way to enhance the transmission efficiency. This paper introduces the overall structure of RC@ SEU （ regional center @ Southeast University） in AMS （alpha magnetic spectrometer）-02 ground data transfer system as well as the experiments conducted in CERNET （China Education and Research Network）/CERNET2 and global academic Internet. The effects of the number of parallel streams and TCP buffer size are tested. The test confirms that in the current circumstance of CERNET, to find the fight number of parallel TCP connections is the main method to improve the throughput. TCP buffer size tuning has little effect now, but may have good effects when the available bandwidth becomes higher.展开更多
To analyze a multibody system composed of non-uniform beam and spring-mass subsystems, the model discretization is carried on by utilizing the finite element method（FEM）, the dynamic model of non-uniform beam is dev...To analyze a multibody system composed of non-uniform beam and spring-mass subsystems, the model discretization is carried on by utilizing the finite element method（FEM）, the dynamic model of non-uniform beam is developed by using the transfer matrix method of multibody system（MS-TMM）, the transfer matrix of non-u- niform beam is derived, and the natural frequencies are computed. Compared with the numerical assembly method （NAM）, the results by MS-TMM have good agreement with the results by FEM, and are better than the results by NAM. When using the high precision method, the global dynamic equations of the complex multibody system are not needed and the orders of involved system matrices are decreased greatly. For the investigation on the re- verse problem of the physical parameter identification of multibody system, MS-TMM and the optimization tech- nology based on genetic algorithms（GAs） are combined and extended. The identification problem is exchanged for an optimization problem, and it is formulated as a global minimum solution of the objective function with respect to natural frequencies of multibody system. At last, the numerical example of non-uniform beam with attach- ments is discussed, and the identification results indicate the feasibility and the effectivity of the proposed aop- proach.展开更多
The electrochemical and the mass transport behavior of ABTS2-/ABTS＇- （2,2＇-azinobis（3- ethylbenzothiazoline-6-sulfonate）） redox couple at glassy carbon electrode （GCE） in phos- phate buffer solution （PBS, pH=...The electrochemical and the mass transport behavior of ABTS2-/ABTS＇- （2,2＇-azinobis（3- ethylbenzothiazoline-6-sulfonate）） redox couple at glassy carbon electrode （GCE） in phos- phate buffer solution （PBS, pH=4.4） is studied in detail by cyclic voltammetry combined with rotating disk electrode system. From the i-E curves recorded at different electrode rotating rate, rate constant, and transfer coefficient for ABTS 2-←→ABTS^-＋e reaction at GCE electrode and the diffusion coefficient of ABTS2- in PBS are estimated to be 4.6× 10^-3 cm/s, 0.28, and 4.4× 10^-6 cm^2/s, respectively. The transfer coefficient with a value of ca. 0.28 differs largely from the value of 0.5 that is always assumed in the literature. The origins for the difference of the rate constant determined and the challenges for estimating the stan- dard rate constant are discussed. The performance for such ABTS2- mediated bio-cathode toward oxygen reduction reaction is discussed according to the over-potential drop as well as current output limit associated with the charge transfer kinetics of ABTS2- ←→ABTS-＋e redox reaction and/or the mass transport effect.展开更多
This paper proposes a cochlear prosthetic system with an implanted digital signal processor （DSP）. This system transmits voice-band signals with a low data rate through the wireless link, free of the data-rate limit...This paper proposes a cochlear prosthetic system with an implanted digital signal processor （DSP）. This system transmits voice-band signals with a low data rate through the wireless link, free of the data-rate limitation and suitable for future development. By optimizing the speech processing algorithm and the DSP hardware design, the implanted DSP manages to execute the continuous interleaved sampling （CIS） algorithm at a clock frequency of 3MHz and a power consumption of only 1.91mW. With an analytic power-transmission efficiency of the wireless inductive link （40%）, the power overhead caused by the implanted DSP is derived as 2.87roW,which is trivial when compared with the power consumption of existing cochlear prosthetic systems （tens of milliwatts）. With the DSP implanted,this new system can.be easily developed into a fully implanted cochlear prosthesis.展开更多
Numerical study was performed to evaluate the characteristics of combined heat transfer of radiation, conduction and convection in indirect near infrared ray （N/R） heating chamber. The effects of important design pa...Numerical study was performed to evaluate the characteristics of combined heat transfer of radiation, conduction and convection in indirect near infrared ray （N/R） heating chamber. The effects of important design parameters such as the shape of heat absorbing cylinder and heat releasing fin on the pressure drop and heat transfer coefficient were analyzed with different Reynolds numbers. The Reynolds numbers were varied from 103 to 3x106, which was defined based on the hydraulic diameter of the heat absorbing cylinder. Analyses were performed to obtain the inner and outer flow and the temperature distributions in the heat absorbing cylinder and the rates of radiation heat transfer and convection heat transfer. As the Reynolds number increases, the convection heat transfer rate is increased while the radiation heat transfer rate is decreased. The average convection heat transfer rate follows a power rule of the Reynolds number. Addition of three-dimensional heat releasing fin to the outside of the heat absorbing cylinder enhances the convection heat transfer.展开更多
Human body communication is proposed as a promising body proximal comanunication tech- nology for body sensor networks. To achieve low power and slmll volume ill the sensor nodes, a Ra-dio Frequency （RF） application...Human body communication is proposed as a promising body proximal comanunication tech- nology for body sensor networks. To achieve low power and slmll volume ill the sensor nodes, a Ra-dio Frequency （RF） application-specific integrated circuit transceiver tbr Human Body Commnunication （HBC） is presented and the characteristics of HBC are investigated. A high data rate On-Off Keying （OOK）/Frequency-Shift Keying （FSK） modulation protocol and an OOK/FSK delrodulator circuit are introduced in this paper, with a data-rate-to-carrier-frequency ratio up to 70%. A low noise amplifier is proposed to handle the dynamic range problem and improve the sensitivity of the receiver path. In addi-tion, a low power autonmatic-gain-control system is realized using a novel architecture, thereby render-ing the peak detector circuit and loop filter unneces-sary. Finally, the complete chip is fabricated. Simula-tion results suggest receiver sensitivity to be-75 dBm. The transceiver shows an overall power con-smxption of 32 mW when data rate is 5 Mbps, de-livering a P1dB output power of - 30 dBm.展开更多
Energy efficiency(EE) is a key requirement for the design of short-range communication network.In order to alleviate energy consumption(EC) constraint,a novel layered heterogeneous mobile cloud architecture is propose...Energy efficiency(EE) is a key requirement for the design of short-range communication network.In order to alleviate energy consumption(EC) constraint,a novel layered heterogeneous mobile cloud architecture is proposed in this paper.Based on the proposed layered heterogeneous mobile cloud architecture,we establish an appropriate energy consumption model,and design an energy efficiency scheme based on joint data packet fragmentation and cooperative transmission and analyze the energy efficiency corresponding to different packet sizes and the cloud size.Simulation results show that,when all nodes of the cloud are accessing the same size of data packet fragmentation,the proposed layered heterogeneous mobile cloud architecture can provide significant energy savings.The results provide useful insights into the possible operation of the strategies and show that significant energy consumption reductions are possible.展开更多
Numerical analysis was performed to investigate flow and heat transfer characteristics in spiral coiled tube heat exchanger. Radius of curvature of the spiral coiled tube was gradually increased as total rotating angl...Numerical analysis was performed to investigate flow and heat transfer characteristics in spiral coiled tube heat exchanger. Radius of curvature of the spiral coiled tube was gradually increased as total rotating angle reached 12n. As the varying radius of curvature became a dominant flow parameter, three-dimensional flow analysis was performed to this flow together with different Reynolds numbers while constant wall heat flux condition was set in thermal field. From the analysis, centrifugal force due to curvature effect is found to have significant role in behavior of pressure drop and heat transfer. The centrifugal force enhances pressure drop and heat transfer to have generally higher values in the spiral coiled tube than those in the straight tube. Even then, friction factor and Nusselt number are found to follow the proportionality with square root of the Dean number. Individual effect of flow parameters of Reynolds number and curvature ratio was investigated and effect of Reynolds number is found to be stronger than that of curvature effect.展开更多
The paper presents a kind of transmission system which employs M-ary Position Phase Shift Keying(MPPSK) to send data and Phase Locked Loop(PLL) based techniques for data retrieve.With a single PLL, MPPSK demodulation ...The paper presents a kind of transmission system which employs M-ary Position Phase Shift Keying(MPPSK) to send data and Phase Locked Loop(PLL) based techniques for data retrieve.With a single PLL, MPPSK demodulation is achieved, as well as carrier recovery and symbol synchronization.Firstly, MPPSK modulation method is briefly introduced.2PPSK's PSD expression is given with its optimization result.Orthogonal Phase Detector(PD) and static threshold are used for the purpose of wider phase range and simplicity in demodulation.The data rate is alterable, which is 4.65 kbps for 2PPSK and 9.3 kbps for 4PPSK in the paper.Then some indicative comparisons in Signal to Noise Ratio Symbol Error Rate(SNR-SER) are made among 2PPSK, 3PPSK and 4PPSK, of which 4PPSK has proved to be optimal in ten slots each symbol conditions.And finally, it is demonstrated by system simulations that lower than 10-4 Symbol Error Rate(SER) performance can be obtained at 13 dB symbol SNR.展开更多
ObjectiveThe aim was to assess genetic and physiological toxicity of wastewater from a pharmaceutical factory using root tip micronucleus technology of Vicia faba. MethodThe pollution of wastewater from a pharmaceutic...ObjectiveThe aim was to assess genetic and physiological toxicity of wastewater from a pharmaceutical factory using root tip micronucleus technology of Vicia faba. MethodThe pollution of wastewater from a pharmaceutical factory was detected by using root tip micronucleus technology of Vicia faba, and the genetic and physiological toxicity of the wastewater to Vicia faba was assessed. ResultNon-processed wastewater had an extremely high level of biological toxicity; the cells were unable to live with the wastewater at a high concentration; the cells were able to grow with the wastewater at a low concentration, though the micronucleus ratio was extremely high. The processed wastewater had no significant impact on cell growth, but the micronucleus ratio was extremely high, showing that the processed water also had a high pollution index. ConclusionThe research could provide scientific references for the national treatment of wastewater from a pharmaceutical factory.展开更多
Adsorbents are important components in adsorption refrigeration. The diameter of an adsorbent can affect the heat and mass transfer of an adsorber. The effect of particle diameter on effective thermal conductivity was...Adsorbents are important components in adsorption refrigeration. The diameter of an adsorbent can affect the heat and mass transfer of an adsorber. The effect of particle diameter on effective thermal conductivity was investigated. The heat transfer coefficient of the refrigerant and the void rate of the adsorbent layer can also affect the effective thermal conductivity of adsorbents. The performance of mass transfer in the adsorber is better when pressure drop decreases. Pressure drop decreases with increasing permeability. The permeability of the adsorbent layer can be improved with increasing adsorbent diameter. The effect of adsorbent diameter on refrigeration output power was experimentally studied. Output power initially increases and then decreases with increasing diameter under different cycle time conditions. Output power increases with decreasing cycle time under similar diameters.展开更多
Low Voltage Differential Signaling (LVDS) has become a popular choice for high-speed serial links to conquer the bandwidth bottleneck of intra-chip data transmission. This paper presents the design and the implementat...Low Voltage Differential Signaling (LVDS) has become a popular choice for high-speed serial links to conquer the bandwidth bottleneck of intra-chip data transmission. This paper presents the design and the implementation of LVDS Input/Output (I/O) interface circuits in a standard 0.18 μm CMOS technology using thick gate oxide devices (3.3 V), fully compatible with LVDS standard. In the proposed transmitter, a novel Common-Mode FeedBack (CMFB)circuit is utilized to keep the common-mode output voltage stable over Process, supply Voltage and Temperature (PVT) variations. Because there are no area greedy resistors in the CMFB circuitry, the disadvantage of large die area in existing transmitter structures is avoided. To obtain sufficient gain, the receiver consists of three am- plifying stages: a voltage amplifying stage, a transconductance amplifying stage, and a transimpedance amplifying stage. And to exclude inner nodes with high RC time constant, shunt-shunt negative feedback is introduced in the receiver. A novel active inductor shunt peaking structure is used in the receiver to fulfill the stringent requirements of high speed and wide Common-Mode Input Region (CMIR) without voltage gain, power dissipation and silicon area penalty. Simulation results show that data rates of 2 Gbps and 2.5 Gbps are achieved for the transmitter and receiver with power con- sumption of 13.2 mW and 8.3 mW respectively.展开更多
An experimental study on intensifying osmotic dehydration was carried out ina state of nature and with acoustic cavitation of different cavitating intensity (0.5A, 0.7A and0.9A) respectively, in which the material is ...An experimental study on intensifying osmotic dehydration was carried out ina state of nature and with acoustic cavitation of different cavitating intensity (0.5A, 0.7A and0.9A) respectively, in which the material is apple slice of 5mm thickness. The result showed thatacoustic cavitation remarkably enhanced the osmotic dehydration, and the water loss was acceleratedwith the increase of cavitating intensity. The water diffusivity coefficients ranged from1.8x10^(-10)m^2·s^(-1) at 0.5A to 2.6x10^(-10)m^2·s^(-1) at 0.9A, and solute diffusivitycoefficients ranged from 3.5x10^(-11) m^2·s^(-1) at 0.5A to 4.6X10^(-11)m^2·s^(-1) at 0.9A. On thebasis of experiments, a mathematical model was established about mass transfer during osmoticdehydration, and the numerical simulation was carried out. The calculated results agree well withexperimental data, and represent the rule of mass transfer during osmotic dehydration intensified byacoustic cavitation.展开更多
A P-vector method was optimized using variational data assimilation technique, with which the vertical structures and seasonal variations of zonal velocities and transports were investigated. The results showed that w...A P-vector method was optimized using variational data assimilation technique, with which the vertical structures and seasonal variations of zonal velocities and transports were investigated. The results showed that westward and eastward flowes occur in the Luzon Strait in the same period in a year. However the net volume transport is westward. In the upper level (0m -500m),the westward flow exits in the middle and south of the Luzon Strait, and the eastward flow exits in the north. There are two centers of westward flow and one center of eastward flow. In the middle of the Luzon Strait, westward and eastward flowes appear alternately in vertical direction. The westward flow strengthens in winter and weakens in summer. The net volume transport is strong in winter (5.53 Sv) but weak in summer (0.29 Sv). Except in summer, the volume transport in the upper level accounts for more than half of the total volume transport (0m bottom). In summer, the net volume transport in the upper level is eastward (1.01 Sv), but westward underneath.展开更多
This paper presents a Dynamic Cross-layer Data Queue Management approach (DC-DQM) based on priority to address the priority deviation problem in Delay-Tolerant Mobile Sensor Networks (DT-MSNs). Receiver-driven data de...This paper presents a Dynamic Cross-layer Data Queue Management approach (DC-DQM) based on priority to address the priority deviation problem in Delay-Tolerant Mobile Sensor Networks (DT-MSNs). Receiver-driven data delivery scheme is used for fast response to data transfers, and a priority based interaction model is adopted to identify the data priority. Three interactive parameters are introduced to prioritize and dynamically manage data queue. The experimental results show that it can ameliorate data delivery ratio and achieve good performance in terms of average delay.展开更多
Multi-target tracking(MTT) is a research hotspot of wireless sensor networks at present.A self-organized dynamic cluster task allocation scheme is used to implement collaborative task allocation for MTT in WSN and a s...Multi-target tracking(MTT) is a research hotspot of wireless sensor networks at present.A self-organized dynamic cluster task allocation scheme is used to implement collaborative task allocation for MTT in WSN and a special cluster member(CM) node selection method is put forward in the scheme.An energy efficiency model was proposed under consideration of both energy consumption and remaining energy balance in the network.A tracking accuracy model based on area-sum principle was also presented through analyzing the localization accuracy of triangulation.Then,the two models mentioned above were combined to establish dynamic cluster member selection model for MTT where a comprehensive performance index function was designed to guide the CM node selection.This selection was fulfilled using genetic algorithm.Simulation results show that this method keeps both energy efficiency and tracking quality in optimal state,and also indicate the validity of genetic algorithm in implementing CM node selection.展开更多
This paper describes a high security data transmission system over X-band microwave frequency. The paper has two parts. The first part deals with encryption of binary data by Advanced Encryption Standard (AES) using V...This paper describes a high security data transmission system over X-band microwave frequency. The paper has two parts. The first part deals with encryption of binary data by Advanced Encryption Standard (AES) using VHDL modeling of Field Programmable Gate Array (FPGA). The second part deals with a novel idea of transmitting the encrypted data by using a single klystron. This requires the simultaneous generation of a pair of two independent RF frequencies from a reflex klystron working for X-band frequency range. In this scheme, the klystron is suitably biased on the repeller terminal and superimposed on a train of AES encrypted binary data so as to create two RF frequencies one corresponding to negative peaks and the other one to the positive peaks of the data resulting in an Frequency Shift Keying (FSK) signal. The results have been verified experimentally.展开更多
文摘Background,aim,and scope Soil saturated hydraulic conductivity(K_(s))is a key parameter in the hydrological cycle of soil;however,we have very limited understanding of K_(s) characteristics and the factors that inf luence this key parameter in the Mu Us sandy land(MUSL).Quantifying the impact of changes in land use in the Mu Us sandy land on K_(s) will provide a key foundation for understanding the regional water cycle,but will also provide a scientific basis for the governance of the MUSL.Materials and methods In this study,we determined K_(s) and the basic physical and chemical properties of soil(i.e.,organic matter,bulk density,and soil particle composition)within the first 100 cm layer of four different land use patterns(farmland,tree,shrub,and grassland)in the MUSL.The vertical variation of K_(s) and the factors that influence this key parameter were analyzed and a transfer function for estimating K_(s) was established based on a multiple stepwise regression model.Results The K_(s) of farmland,tree,and shrub increased gradually with soil depth while that of grassland remained unchanged.The K_(s) of the four patterns of land use were moderately variable;mean K_(s)values were ranked as follows:grassland(1.38 mm·min^(-1))<tree(1.76 mm·min^(-1))<farmland(1.82 mm·min^(-1))<shrub(3.30 mm·min^(-1)).The correlation between K_(s) and organic matter,bulk density,and soil particle composition,varied across different land use patterns.A multiple stepwise regression model showed that silt,coarse sand,bulk density,and organic matter,were key predictive factors for the K_(s) of farmland,tree,shrub,and grassland,in the MUSL.Discussion The vertical distribution trend for K_(s) in farmland is known to be predominantly influenced by cultivation,fertilization,and other factors.The general aim is to improve the water-holding capacity of shallow soil on farmland(0-30 cm in depth)to conserve water and nutrients;research has shown that the K_(s) of farmland increases with soil depth.The root growth of tree and shrub in sandy land exerts mechanical force on the soil due to biophysical processes involving rhizospheres,thus leading to a significant change in K_(s).We found that shallow high-density fine roots increased the volume of soil pores and eliminated large pores,thus resulting in a reduction in shallow K_(s).Therefore,the K_(s) of tree and shrub increased with soil depth.Analysis also showed that the K_(s) of grassland did not change significantly and exhibited the lowest mean value when compared to other land use patterns.This finding was predominantly due to the shallow root system of grasslands and because this land use pattern is not subject to human activities such as cultivation and fertilization;consequently,there was no significant change in K_(s) with depth;grassland also had the lowest mean K_(s).We also established a transfer function for K_(s) for different land use patterns in the MUSL.However,the predictive factors for K_(s) in different land use patterns are known to be affected by soil cultivation methods,vegetation restoration modes,the distribution of soil moisture,and other factors,thus resulting in key differences.Therefore,when using the transfer function to predict K_(s) in other areas,it will be necessary to perform parameter calibration and further verification.Conclusions In the MUSL,the K_(s) of farmland,tree,and shrub gradually increased with soil depth;however,the K_(s) of grassland showed no significant variation in terms of vertical distribution.The mean K_(s) values of different land use patterns were ranked as follows:shrub>farmland>tree>grassland;all land use patterns showed moderate levels of variability.The K_(s) for different land use patterns exhibited differing degrees of correlation with soil physical and chemical properties;of these,clay,silt,sand,bulk density,and organic matter,were identified as important variables for predicting K_(s) in farmland,tree,shrub,and grassland,respectively.Recommendations and perspectives In this study,we used a stepwise multiple regression model to establish a transfer function prediction model for K_(s) for different land use patterns;this model possessed high estimation accuracy.The ability to predict K_(s) in the MUSL is very important in terms of the conservation of water and nutrients.
基金The National Basic Research Program of China (973Program) (No.2003CB314803).
文摘To increase the performance of bulk data transfer mission with ultra-long TCP （ transmission control protocol） connection in high-energy physics experiments, a series of experiments were conducted to explore the way to enhance the transmission efficiency. This paper introduces the overall structure of RC@ SEU （ regional center @ Southeast University） in AMS （alpha magnetic spectrometer）-02 ground data transfer system as well as the experiments conducted in CERNET （China Education and Research Network）/CERNET2 and global academic Internet. The effects of the number of parallel streams and TCP buffer size are tested. The test confirms that in the current circumstance of CERNET, to find the fight number of parallel TCP connections is the main method to improve the throughput. TCP buffer size tuning has little effect now, but may have good effects when the available bandwidth becomes higher.
基金Supported by the National Natural Science Foundation of China(10902051)the Natural Science Foundation of Jiangsu Province(BK2008046)~~
文摘To analyze a multibody system composed of non-uniform beam and spring-mass subsystems, the model discretization is carried on by utilizing the finite element method（FEM）, the dynamic model of non-uniform beam is developed by using the transfer matrix method of multibody system（MS-TMM）, the transfer matrix of non-u- niform beam is derived, and the natural frequencies are computed. Compared with the numerical assembly method （NAM）, the results by MS-TMM have good agreement with the results by FEM, and are better than the results by NAM. When using the high precision method, the global dynamic equations of the complex multibody system are not needed and the orders of involved system matrices are decreased greatly. For the investigation on the re- verse problem of the physical parameter identification of multibody system, MS-TMM and the optimization tech- nology based on genetic algorithms（GAs） are combined and extended. The identification problem is exchanged for an optimization problem, and it is formulated as a global minimum solution of the objective function with respect to natural frequencies of multibody system. At last, the numerical example of non-uniform beam with attach- ments is discussed, and the identification results indicate the feasibility and the effectivity of the proposed aop- proach.
基金This work was supported by one hundred Talents＇ Program of the Chinese Academy of Science, the National Natural Science Foundation of China （No.21073176）, 973 Program from the Ministry of Science and Technology of China （No.2010CB923302）.
文摘The electrochemical and the mass transport behavior of ABTS2-/ABTS＇- （2,2＇-azinobis（3- ethylbenzothiazoline-6-sulfonate）） redox couple at glassy carbon electrode （GCE） in phos- phate buffer solution （PBS, pH=4.4） is studied in detail by cyclic voltammetry combined with rotating disk electrode system. From the i-E curves recorded at different electrode rotating rate, rate constant, and transfer coefficient for ABTS 2-←→ABTS^-＋e reaction at GCE electrode and the diffusion coefficient of ABTS2- in PBS are estimated to be 4.6× 10^-3 cm/s, 0.28, and 4.4× 10^-6 cm^2/s, respectively. The transfer coefficient with a value of ca. 0.28 differs largely from the value of 0.5 that is always assumed in the literature. The origins for the difference of the rate constant determined and the challenges for estimating the stan- dard rate constant are discussed. The performance for such ABTS2- mediated bio-cathode toward oxygen reduction reaction is discussed according to the over-potential drop as well as current output limit associated with the charge transfer kinetics of ABTS2- ←→ABTS-＋e redox reaction and/or the mass transport effect.
基金the National Natural Science Foundation of China(No.60475018)~~
文摘This paper proposes a cochlear prosthetic system with an implanted digital signal processor （DSP）. This system transmits voice-band signals with a low data rate through the wireless link, free of the data-rate limitation and suitable for future development. By optimizing the speech processing algorithm and the DSP hardware design, the implanted DSP manages to execute the continuous interleaved sampling （CIS） algorithm at a clock frequency of 3MHz and a power consumption of only 1.91mW. With an analytic power-transmission efficiency of the wireless inductive link （40%）, the power overhead caused by the implanted DSP is derived as 2.87roW,which is trivial when compared with the power consumption of existing cochlear prosthetic systems （tens of milliwatts）. With the DSP implanted,this new system can.be easily developed into a fully implanted cochlear prosthesis.
基金supported by the Second Stage of Brain Korea 21 Projects
文摘Numerical study was performed to evaluate the characteristics of combined heat transfer of radiation, conduction and convection in indirect near infrared ray （N/R） heating chamber. The effects of important design parameters such as the shape of heat absorbing cylinder and heat releasing fin on the pressure drop and heat transfer coefficient were analyzed with different Reynolds numbers. The Reynolds numbers were varied from 103 to 3x106, which was defined based on the hydraulic diameter of the heat absorbing cylinder. Analyses were performed to obtain the inner and outer flow and the temperature distributions in the heat absorbing cylinder and the rates of radiation heat transfer and convection heat transfer. As the Reynolds number increases, the convection heat transfer rate is increased while the radiation heat transfer rate is decreased. The average convection heat transfer rate follows a power rule of the Reynolds number. Addition of three-dimensional heat releasing fin to the outside of the heat absorbing cylinder enhances the convection heat transfer.
基金This study was supported partially by the Projects of National Natural Science Foundation of China under Crants No. 60932001, No.61072031 the National 863 Program of China un-der Crant No. 2012AA02A604+3 种基金 the National 973 Program of China under Cwant No. 2010CB732606 the Next Generation Communication Technology Major Project of National S＆T un-der Crant No. 2013ZX03005013 the ＂One-hundred Talent＂ and the ＂Low-cost Healthcare＂ Programs of Chinese Academy of Sciences and the Guangdong Innovation Research Team Funds for Low-cost Healthcare and Irrage-Guided Therapy.
文摘Human body communication is proposed as a promising body proximal comanunication tech- nology for body sensor networks. To achieve low power and slmll volume ill the sensor nodes, a Ra-dio Frequency （RF） application-specific integrated circuit transceiver tbr Human Body Commnunication （HBC） is presented and the characteristics of HBC are investigated. A high data rate On-Off Keying （OOK）/Frequency-Shift Keying （FSK） modulation protocol and an OOK/FSK delrodulator circuit are introduced in this paper, with a data-rate-to-carrier-frequency ratio up to 70%. A low noise amplifier is proposed to handle the dynamic range problem and improve the sensitivity of the receiver path. In addi-tion, a low power autonmatic-gain-control system is realized using a novel architecture, thereby render-ing the peak detector circuit and loop filter unneces-sary. Finally, the complete chip is fabricated. Simula-tion results suggest receiver sensitivity to be-75 dBm. The transceiver shows an overall power con-smxption of 32 mW when data rate is 5 Mbps, de-livering a P1dB output power of - 30 dBm.
基金jointly supported by the Chongqing Municipal Natural Science Foundation under Grant No.CSTC2013jjB40001)the National High Technology Research and Development Program of China(863Program)under Grant No.20140908the Program for Changjiang Scholars and Innovative Research Team in University under Grant No.IRT1299
文摘Energy efficiency(EE) is a key requirement for the design of short-range communication network.In order to alleviate energy consumption(EC) constraint,a novel layered heterogeneous mobile cloud architecture is proposed in this paper.Based on the proposed layered heterogeneous mobile cloud architecture,we establish an appropriate energy consumption model,and design an energy efficiency scheme based on joint data packet fragmentation and cooperative transmission and analyze the energy efficiency corresponding to different packet sizes and the cloud size.Simulation results show that,when all nodes of the cloud are accessing the same size of data packet fragmentation,the proposed layered heterogeneous mobile cloud architecture can provide significant energy savings.The results provide useful insights into the possible operation of the strategies and show that significant energy consumption reductions are possible.
基金supported by the Second Stage of Brain Korea 21 Projects,Korea
文摘Numerical analysis was performed to investigate flow and heat transfer characteristics in spiral coiled tube heat exchanger. Radius of curvature of the spiral coiled tube was gradually increased as total rotating angle reached 12n. As the varying radius of curvature became a dominant flow parameter, three-dimensional flow analysis was performed to this flow together with different Reynolds numbers while constant wall heat flux condition was set in thermal field. From the analysis, centrifugal force due to curvature effect is found to have significant role in behavior of pressure drop and heat transfer. The centrifugal force enhances pressure drop and heat transfer to have generally higher values in the spiral coiled tube than those in the straight tube. Even then, friction factor and Nusselt number are found to follow the proportionality with square root of the Dean number. Individual effect of flow parameters of Reynolds number and curvature ratio was investigated and effect of Reynolds number is found to be stronger than that of curvature effect.
基金Supported by National Natural Science Foundation of China (60472054)
文摘The paper presents a kind of transmission system which employs M-ary Position Phase Shift Keying(MPPSK) to send data and Phase Locked Loop(PLL) based techniques for data retrieve.With a single PLL, MPPSK demodulation is achieved, as well as carrier recovery and symbol synchronization.Firstly, MPPSK modulation method is briefly introduced.2PPSK's PSD expression is given with its optimization result.Orthogonal Phase Detector(PD) and static threshold are used for the purpose of wider phase range and simplicity in demodulation.The data rate is alterable, which is 4.65 kbps for 2PPSK and 9.3 kbps for 4PPSK in the paper.Then some indicative comparisons in Signal to Noise Ratio Symbol Error Rate(SNR-SER) are made among 2PPSK, 3PPSK and 4PPSK, of which 4PPSK has proved to be optimal in ten slots each symbol conditions.And finally, it is demonstrated by system simulations that lower than 10-4 Symbol Error Rate(SER) performance can be obtained at 13 dB symbol SNR.
文摘ObjectiveThe aim was to assess genetic and physiological toxicity of wastewater from a pharmaceutical factory using root tip micronucleus technology of Vicia faba. MethodThe pollution of wastewater from a pharmaceutical factory was detected by using root tip micronucleus technology of Vicia faba, and the genetic and physiological toxicity of the wastewater to Vicia faba was assessed. ResultNon-processed wastewater had an extremely high level of biological toxicity; the cells were unable to live with the wastewater at a high concentration; the cells were able to grow with the wastewater at a low concentration, though the micronucleus ratio was extremely high. The processed wastewater had no significant impact on cell growth, but the micronucleus ratio was extremely high, showing that the processed water also had a high pollution index. ConclusionThe research could provide scientific references for the national treatment of wastewater from a pharmaceutical factory.
基金Supported by the Chinese Academy of Science Visiting Professorship for Senior International Scientists project(2009Z2-1973)
文摘Adsorbents are important components in adsorption refrigeration. The diameter of an adsorbent can affect the heat and mass transfer of an adsorber. The effect of particle diameter on effective thermal conductivity was investigated. The heat transfer coefficient of the refrigerant and the void rate of the adsorbent layer can also affect the effective thermal conductivity of adsorbents. The performance of mass transfer in the adsorber is better when pressure drop decreases. Pressure drop decreases with increasing permeability. The permeability of the adsorbent layer can be improved with increasing adsorbent diameter. The effect of adsorbent diameter on refrigeration output power was experimentally studied. Output power initially increases and then decreases with increasing diameter under different cycle time conditions. Output power increases with decreasing cycle time under similar diameters.
文摘Low Voltage Differential Signaling (LVDS) has become a popular choice for high-speed serial links to conquer the bandwidth bottleneck of intra-chip data transmission. This paper presents the design and the implementation of LVDS Input/Output (I/O) interface circuits in a standard 0.18 μm CMOS technology using thick gate oxide devices (3.3 V), fully compatible with LVDS standard. In the proposed transmitter, a novel Common-Mode FeedBack (CMFB)circuit is utilized to keep the common-mode output voltage stable over Process, supply Voltage and Temperature (PVT) variations. Because there are no area greedy resistors in the CMFB circuitry, the disadvantage of large die area in existing transmitter structures is avoided. To obtain sufficient gain, the receiver consists of three am- plifying stages: a voltage amplifying stage, a transconductance amplifying stage, and a transimpedance amplifying stage. And to exclude inner nodes with high RC time constant, shunt-shunt negative feedback is introduced in the receiver. A novel active inductor shunt peaking structure is used in the receiver to fulfill the stringent requirements of high speed and wide Common-Mode Input Region (CMIR) without voltage gain, power dissipation and silicon area penalty. Simulation results show that data rates of 2 Gbps and 2.5 Gbps are achieved for the transmitter and receiver with power con- sumption of 13.2 mW and 8.3 mW respectively.
文摘An experimental study on intensifying osmotic dehydration was carried out ina state of nature and with acoustic cavitation of different cavitating intensity (0.5A, 0.7A and0.9A) respectively, in which the material is apple slice of 5mm thickness. The result showed thatacoustic cavitation remarkably enhanced the osmotic dehydration, and the water loss was acceleratedwith the increase of cavitating intensity. The water diffusivity coefficients ranged from1.8x10^(-10)m^2·s^(-1) at 0.5A to 2.6x10^(-10)m^2·s^(-1) at 0.9A, and solute diffusivitycoefficients ranged from 3.5x10^(-11) m^2·s^(-1) at 0.5A to 4.6X10^(-11)m^2·s^(-1) at 0.9A. On thebasis of experiments, a mathematical model was established about mass transfer during osmoticdehydration, and the numerical simulation was carried out. The calculated results agree well withexperimental data, and represent the rule of mass transfer during osmotic dehydration intensified byacoustic cavitation.
基金Supported by the Major State Basic Research Program (No. G1999043810) Open Laboratory for Tropical Marine Environmental Dynamics (LED)+2 种基金 South China Sea Institute of Oceanology Chinese Academy of Sciences and the NSFC (No. 40306004).
文摘A P-vector method was optimized using variational data assimilation technique, with which the vertical structures and seasonal variations of zonal velocities and transports were investigated. The results showed that westward and eastward flowes occur in the Luzon Strait in the same period in a year. However the net volume transport is westward. In the upper level (0m -500m),the westward flow exits in the middle and south of the Luzon Strait, and the eastward flow exits in the north. There are two centers of westward flow and one center of eastward flow. In the middle of the Luzon Strait, westward and eastward flowes appear alternately in vertical direction. The westward flow strengthens in winter and weakens in summer. The net volume transport is strong in winter (5.53 Sv) but weak in summer (0.29 Sv). Except in summer, the volume transport in the upper level accounts for more than half of the total volume transport (0m bottom). In summer, the net volume transport in the upper level is eastward (1.01 Sv), but westward underneath.
基金Supported by the Anhui Provincial Natural Science Foundation (No. 2012AKZR0330)Postdoctoral Science Foundation of China (No. 2012M521247)the Fundamental Research Funds for the Central Universities
文摘This paper presents a Dynamic Cross-layer Data Queue Management approach (DC-DQM) based on priority to address the priority deviation problem in Delay-Tolerant Mobile Sensor Networks (DT-MSNs). Receiver-driven data delivery scheme is used for fast response to data transfers, and a priority based interaction model is adopted to identify the data priority. Three interactive parameters are introduced to prioritize and dynamically manage data queue. The experimental results show that it can ameliorate data delivery ratio and achieve good performance in terms of average delay.
基金Projects(90820302,60805027)supported by the National Natural Science Foundation of ChinaProject(200805330005)supported by the Research Fund for the Doctoral Program of Higher Education,ChinaProject(2009FJ4030)supported by Academician Foundation of Hunan Province,China
文摘Multi-target tracking(MTT) is a research hotspot of wireless sensor networks at present.A self-organized dynamic cluster task allocation scheme is used to implement collaborative task allocation for MTT in WSN and a special cluster member(CM) node selection method is put forward in the scheme.An energy efficiency model was proposed under consideration of both energy consumption and remaining energy balance in the network.A tracking accuracy model based on area-sum principle was also presented through analyzing the localization accuracy of triangulation.Then,the two models mentioned above were combined to establish dynamic cluster member selection model for MTT where a comprehensive performance index function was designed to guide the CM node selection.This selection was fulfilled using genetic algorithm.Simulation results show that this method keeps both energy efficiency and tracking quality in optimal state,and also indicate the validity of genetic algorithm in implementing CM node selection.
文摘This paper describes a high security data transmission system over X-band microwave frequency. The paper has two parts. The first part deals with encryption of binary data by Advanced Encryption Standard (AES) using VHDL modeling of Field Programmable Gate Array (FPGA). The second part deals with a novel idea of transmitting the encrypted data by using a single klystron. This requires the simultaneous generation of a pair of two independent RF frequencies from a reflex klystron working for X-band frequency range. In this scheme, the klystron is suitably biased on the repeller terminal and superimposed on a train of AES encrypted binary data so as to create two RF frequencies one corresponding to negative peaks and the other one to the positive peaks of the data resulting in an Frequency Shift Keying (FSK) signal. The results have been verified experimentally.
