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Search Results: 1 - 10 of 78433 matches for " Junping Chen "
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Reduced-Dynamic Precise Orbit Determination for Low Earth Orbiters Based on Helmert Transformation
Junping Chen, Jiexian Wang
Artificial Satellites , 2007, DOI: 10.2478/v10018-0008-008-x
Abstract: A model based on Helmert transformation is presented in reduced-dynamic Precise Orbit Determination(POD). As an implementation, a reduced-dynamic POD approach was developed. The approach includes two steps: firstly, kinematic POD and then reduced-dynamic POD. Based on the approach, a set of programs were developed. POD of CHAMP and GRACE was then carried out. Kinematic and reduced-dynamic POD for CHAMP and GRACE satellite over 2 weeks time show that reduced-dynamic orbits of CHAMP have a mean 3D RMS of 0.26 m compared to PSO orbit of GFZ, and the mean 3D RMS of GRACE-A has the same value compared to GNV1B orbit of JPL. The 3D RMS is reduced by up to 40% compared to kinematic solutions.
A high throughput DNA extraction method with high yield and quality
Xin Zhanguo,Chen Junping
Plant Methods , 2012, DOI: 10.1186/1746-4811-8-26
Abstract: Background Preparation of large quantity and high quality genomic DNA from a large number of plant samples is a major bottleneck for most genetic and genomic analyses, such as, genetic mapping, TILLING (Targeting Induced Local Lesion IN Genome), and next-generation sequencing directly from sheared genomic DNA. A variety of DNA preparation methods and commercial kits are available. However, they are either low throughput, low yield, or costly. Here, we describe a method for high throughput genomic DNA isolation from sorghum [Sorghum bicolor (L.) Moench] leaves and dry seeds with high yield, high quality, and affordable cost. Results We developed a high throughput DNA isolation method by combining a high yield CTAB extraction method with an improved cleanup procedure based on MagAttract kit. The method yielded large quantity and high quality DNA from both lyophilized sorghum leaves and dry seeds. The DNA yield was improved by nearly 30 fold with 4 times less consumption of MagAttract beads. The method can also be used in other plant species, including cotton leaves and pine needles. Conclusion A high throughput system for DNA extraction from sorghum leaves and seeds was developed and validated. The main advantages of the method are low cost, high yield, high quality, and high throughput. One person can process two 96-well plates in a working day at a cost of $0.10 per sample of magnetic beads plus other consumables that other methods will also need.
Genetic Diversity in the Environmental Conditioning of Two Sorghum (Sorghum bicolor L.) Hybrids  [PDF]
John J. Burke, Yves Emendack, Chad Hayes, Junping Chen
American Journal of Plant Sciences (AJPS) , 2018, DOI: 10.4236/ajps.2018.94063
Abstract: Sorghum metabolism continually adapts to environmental temperature as thermal patterns modulate diurnally and seasonally. The degree of adaptation to any given temperature may be difficult to determine from phenotypic responses of the plants. The present study was designed to see if the efficiency of quantum yield of photosystem II could be used as a measure of how well leaf tissue metabolism was able to withstand a prolonged respiratory demand caused by elevated temperatures. The efficiency of quantum yield values of Pioneer 84G62 and Northrup King KS585 commercial sorghum hybrids showed that when the hybrids were grown in a 28°C/20°C day/night cycle in the greenhouse or the field, Pioneer hybrid 84G62 withstood subsequent elevated thermal challenges better than Northrup King KS585. The same hybrids grown in a 39°C/32°C day/night cycle showed similar efficiency of quantum yield values when thermally challenged. Water-deficit stress increased the heat resistance of the tissue raising the efficiency of quantum yield of both lines to the same level. Upon recovery from the water deficit stress the differential efficiency of quantum yield values between the two lines re-appeared. The data provided in this study suggest a metabolic advantage of Pioneer 84G62 to environmental thermal challenges compared with the Northrup King KS585.
Satellite- and Epoch Differenced Precise Point Positioning Based on a Regional Augmentation Network
Haojun Li,Junping Chen,Jiexian Wang,Bin Wu
Sensors , 2012, DOI: 10.3390/s120607518
Abstract: Precise Point Positioning (PPP) has been demonstrated as a simple and effective approach for user positioning. The key issue in PPP is how to shorten convergence time and improve positioning efficiency. Recent researches mainly focus on the ambiguity resolution by correcting residual phase errors at a single station. The success of this approach (referred to hereafter as NORM-PPP) is subject to how rapidly one can fix wide-lane and narrow-lane ambiguities to achieve the first ambiguity-fixed solution. The convergence time of NORM-PPP is receiver type dependent, and normally takes 15–20 min. Different from the general algorithm and theory by which the float ambiguities are estimated and the integer ambiguities are fixed, we concentrate on a differential PPP approach: the satellite- and epoch differenced (SDED) approach. In general, the SDED approach eliminates receiver clocks and ambiguity parameters and thus avoids the complicated residual phase modeling procedure. As a further development of the SDED approach, we use a regional augmentation network to derive tropospheric delay and remaining un-modeled errors at user sites. By adding these corrections and applying the Robust estimation, the weak mathematic properties due to the ED operation is much improved. Implementing this new approach, we need only two epochs of data to achieve PPP positioning converging to centimeter-positioning accuracy. Using seven days of GPS data at six CORS stations in Shanghai, we demonstrate the success rate, defined as the case when three directions converging to desired positioning accuracy of 10 cm, reaches 100% when the interval between the two epochs is longer than 15 min. Comparing the results of 15 min’ interval to that of 10 min’, it is observed that the position RMS improves from 2.47, 3.95, 5.78 cm to 2.21, 3.93, 4.90 cm in the North, East and Up directions, respectively. Combining the SDED coordinates at the starting point and the ED relative coordinates thereafter, we demonstrate the performance of RTK PPP with standard deviation of 0.80, 1.34, 0.97 cm in the North, East and Up directions.
First-principles investigation of the impurity-kink interaction in bcc iron
Tao Yu,LiQun Chen,ChongYu Wang,ZhengChen Qiu,JunPing Du
Chinese Science Bulletin , 2008, DOI: 10.1007/s11434-008-0256-y
Abstract: Using the first-principles self-consistent discrete variational method based on density functional theory, we investigated the effect of light impurities C and N on the electronic structure of kink on the [100](010) edge dislocation (ED) in bcc iron. Our energetic calculations show that the light impurities have a strong segregation tendency to enter the kink. The results of the charge distribution and the local density of states indicate that the strong bonds between the impurity atoms and the neighboring Fe atoms are formed due to the hybridizations of impurity atoms 2p states and Fe 3d4s4p states. The introduction of light impurities can stabilize the kink system, and impedes the sideward motion of the kink in the [100](010) ED. This is, the light impurities induce a strong pinning effect on the [100](010) ED and may result in the solid solute hardening.
Expression and localization of nerve growth factor (NGF) in the testis of alpaca (llama pacos)
Haidong Wang,Yanjun Dong,Wenhua Chen,Junping Hei
Folia Histochemica et Cytobiologica , 2011, DOI: 10.5603/4144
Abstract: During alpaca testis development and spermatogenesis, nerve growth factor (NGF) may play an important role. The main aim of this study was to determine the expression and localization of NGF in the alpaca testis, and to discuss the important role of NGF in alpaca reproductive characteristics. Immunohistochemical staining technique and real-time PCR were used. The expression of NGF in the same cells one-month old (newborn) alpacas 12-month, and 24-month old alpacas showed significant differences (p < 0.05); 12- and 24-month old alpacas showed no significant differences (p > 0.05); NGF at different cell stages showed no significant differences (p > 0.05). It suggests that NGF may be involved in the regulation of spermatogenesis, which provides direct evidence for NGF action in the alpaca testis during postnatal development and spermatogenesis. (Folia Histochemica et Cytobiologica 2011; Vol. 49, No. 1, pp. 55–61)
Expression and localization of nerve growth factor (NGF) in the testis of alpaca (llama pacos)
Haidong Wang,Yanjun Dong,Wenhua Chen,Junping Hei
Folia Histochemica et Cytobiologica , 2011,
Abstract: During alpaca testis development and spermatogenesis, nerve growth factor (NGF) may play an importantrole. The main aim of this study was to determine the expression and localization of NGF in the alpacatestis, and to discuss the important role of NGF in alpaca reproductive characteristics. Immunohistochemicalstaining technique and real-time PCR were used. The expression of NGF in the same cells one-month old(newborn) alpacas 12-month, and 24-month old alpacas showed significant differences (p < 0.05); 12- and24-month old alpacas showed no significant differences (p > 0.05); NGF at different cell stages showed nosignificant differences (p > 0.05). It suggests that NGF may be involved in the regulation of spermatogenesis,which provides direct evidence for NGF action in the alpaca testis during postnatal development and spermatogenesis.
An auxiliary space multigrid preconditioner for the weak Galerkin method
Long Chen,Junping Wang,Yanqiu Wang,Xiu Ye
Mathematics , 2014,
Abstract: In this paper, the authors constructed an auxiliary space multigrid preconditioner for the weak Galerkin finite element method for second-order diffusion equations, discretized on simplicial 2D or 3D meshes. The idea of the auxiliary space multigrid preconditioner is to use an auxiliary space as a "coarse" space in the multigrid algorithm, where the discrete problem in the auxiliary space can be easily solved by an existing solver. In this construction, the authors conveniently use the $H^1$ conforming piecewise linear finite element space as an auxiliary space. The main technical difficulty is to build the connection between the weak Galerkin discrete space and the $H^1$ conforming piecewise linear finite element space. The authors successfully constructed such an auxiliary space multigrid preconditioner for the weak Galerkin method, as well as a reduced system of the weak Galerkin method involving only the degrees of freedom on edges/faces. The preconditioned systems are proved to have condition numbers independent of the mesh size. Numerical experiments are conducted to support the theoretical results.
Numerical Calculation of Dynamic Response for Multi-Span Non-Uniform Beam Subjected to Moving Mass with Friction  [PDF]
Junping Pu, Peng Liu
Engineering (ENG) , 2010, DOI: 10.4236/eng.2010.25048
Abstract: In order to simulate the coupling vibration of a vehicle or train moves on a multi-span continuous bridge with non-uniform cross sections, a moving mass model is used according to the Finite Element Method, the effect of the inertial force, Coriolis force and centrifugal force are considered by means of the additive matrices. For a non-uniform rectangular section beam with both linear and parabolic variable heights in a plane, the stiffness and mass matrices of the beam elements are presented. For a non-uniform box girder, Romberg numerical integral scheme is adopted, each coefficient of the stiffness matrix is obtained by means of a normal numerical computation. By applying these elements to calculate the non-uniform beam, the computational accuracy and efficiency are improved. The finite element method program is worked out and an entire dynamic response process of the beam with non-uniform cross sections subjected to a moving mass is simulated numerically, the results are compared to those previously published for some simple examples. For some complex multi-span bridges subjected to some moving vehicles with changeable velocity and friction, the computational results, which can be regarded as a reference for engineering design and scientific research, are also given simultaneously.
Dynamic Response Analysis of Beams with Oblique Collision  [PDF]
Junping Pu, Yandong Chi
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.37095
Abstract: Adopting a dynamic contact numerical method, some problems such as the central collision, transverse collision and oblique collision between two beams are researched. Numerical expressions for these cases are deduced. Using a self-developed finite element program some examples are computed, and compared with the analytical solution of the central collision, this numerical algorithm is proved to be reliable. For the other numerical results that have no analytical solution to be used to compare with, they are also reasonable through the theoretical analysis. For the transverse and oblique collision, the ideal results can be obtained by using a smaller time step.
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