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Search Results: 1 - 10 of 4870 matches for " Guan Xuemin "
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Optimized Design of Outlets Layout in Thermal Pressure Naturally Ventilated Rooms
Xuemin Sui,Jianping Ma,Yanling Guan
Research Journal of Applied Sciences, Engineering and Technology , 2013,
Abstract: Using thermal pressure ventilation principles to achieve passive ventilation in buildings is an important way to promote green and low consumption building strategy. The reasonable vents layout design can fully tap the potential of thermal pressure ventilation. Aimed to civil buildings with internal heating source, using Computational Fluid Dynamics (CFD) technology, the effects of outlets layout on thermal natural ventilation in rooms were studied. Three types of typical air outlets distribution patterns were considered and the airflow distribution of thermal natural ventilation in rooms was simulated. The ventilation rates and the average workspace temperatures of different simulated conditions were given. The velocity and temperature fields of different simulated conditions were analyzed and the indoor thermal stratification characteristics were discussed. In addition, the effective heat coefficients of different simulated conditions were analyzed and compared. The results show that the strategy of dispersed outlets on ceiling can achieve the optimal natural ventilation effect. The results can provide theoretical references for the design of natural ventilation system in civil buildings.
Allelic Polymorphism Identified and Analysis on the Fifth Exon of Chinese Indigenous Donkey GH Gene by PCR-SSCP
Wenjin Zhu,Yongmei Su,Yanfang Liu,Xuemin Guan,Jing Ni,Jianhua Wu
Journal of Animal and Veterinary Advances , 2012, DOI: 10.3923/javaa.2012.3713.3716
Abstract: Growth of animal is largely regulated by Growth Hormone (GH). In this study the objective was to investigate variations in the fifth exon of GH gene and their polymorphism in 5 Chinese indigenous donkeys by PCR-SSCP and DNA Sequencing Methods. The results showed that there was a transversion at nucleotide position 1802 of GH gene in the 5th exon named as GH-exon5-G1802C which led to a conservative Lysine to Asparagine substitution at amino acid position 205. In detail, two different alleles, A and B were identified and three genotypes were observed, AA, AB and BB with the frequency distribution of allele B from 0.5962-0.7344 in analyzed populations. The genetic diversity analysis revealed that all PIC values were between 0.3140 and 0.3656, implying that this locus within GH gene possessed moderate genetic diversity in 5 Chinese indigenous donkeys. The χ2-test showed that GZ donkey was significant deviation, DZ donkey was no significant deviation from Hardy-Weinberg equilibrium, GL, JN and XJ donkey was not in agreement Hardy-Weinberg equilibrium. The results confirmed that there were polymorphisms in the exon 5 of GH gene.
Polymorphism Analysis on the Second Intron of the GH Gene in Chinese Donkeys
Wenjin Zhu,Yongmei Su,Yanhua Ma,Jing Ni,Xuemin Guan,Jianhua Wu
Journal of Animal and Veterinary Advances , 2012, DOI: 10.3923/javaa.2012.916.918
Abstract: To reveal the genetical diversity of different donkey breeds at molecular level and provid some bases for the breed resource evaluation and utilization of donkeys in China, polymorphism of the second intron of the GH gene was analysised by PCR-SSCP in the seven donkey breeds (LX, GZ, XJ, GL, HB, DZ, JN). The results showed three haplotypes with the percentage of 1.7% in 174 samples were obtained, the haplotype diversity was high as 0.678 and 0.542 for the Linxian and Huaibei donkey and low as 0.077 for Xingiiang donkey with that of 0.409 and 0.462 for Guangling donkey and Guanzhong donkey, respectively with that of 0.355 and 0.304 for Dezhou donkeys and Jinnan donkeys, respectively. The amplified fragments of A and B haplotypes were cloned and sequenced. The result showed the fragments of B haplotypes had one substitution mutation at 735 site (G→C), the fragments of A haplotypes had one substitution mutation at 869 site (G→T). The results confirmed that there were polymorphisms in the second intron (214 bp) of donkey GH gene for the first time.
EFFECT OF SILICON ON THE TRANSITION OF BRITTLENESS IN A NICKEL BASE WROUGHT SUPERALLOY

Wang Yunshi,Bi Jing,Guan Xuemin,Zhang Xizhang,Wang Jingyun,Lin Shuzhi,Xu Anshuang,

金属学报 , 1979,
Abstract: The tensile strength, ductility or impact value of a wrought nickel base super-alloy Ni-15Cr-6W-3Mo-2Al-2Ti depend markedly upon the silicon content of thealloy. On plotting these mechanical properties vs the silicon content which rangesfrom 0.1 to 0.89%, a saddle shown by the existence of a minimum at about 0.4-0.6% Si occurs. There is reason to believe that such a saddle behavior may be caus-ed by the variation of mechanical properties with the type, amount and morpho-logy of carbides as well as with the sequence of carbide precipitation in the alloyas influenced by its silicon content. Thus, the amount of M_6C and M_(23)C_6 precipi-tated along the grain boundaries would appear to proceed in four stages as follows: 1. For silicon content up to 0.1%, globular M_(23)C_6 may be the sole type ofcarbide formed; 2. In the range from 0.1 to 0.4% Si, besides M_(23)C_6, M_6C begins to appearand increases with increase of silicon content. The morphology of the carbidesseems to be different, however, being in a discontinuous, blocky form; 3. In the range from 0.4 to 0.6% Si, continuous films of M_6C were present.As might be expected, this type of carbide is very detrimental to the tensile andimpact properties at room temperature. The precipitation of M_(23)C_6 was slowed downor even suppressed; 4. In the range from 0.6 to 0.89% Si, M_6C may be altered to discontinuous,blocky form, whereas M_(23)C_6 may be very much limited. In conclusion, the detrimental effect of carbide is mainly associated with itsfilm-like morphology especially along the grain boundaries. Of course, carbides ingranular form are good strengtheners. According to prevailing view, criterion for the formation of either M_6C orM_(23)C_6 in nickel base superalloys would seem to be the relative Mo and W con-tents, e. g. if Mo+1/2W>6%, M_6C will be formed. Present work indicates that si-licon plays as equally important role in the formation of M_6C besides the Mo andW contents of the wrought nickel base superalloys.
Baryon QCD sum rules in an external isovector-scalar field and baryon isospin mass splittings
Xuemin Jin
Physics , 1995, DOI: 10.1103/PhysRevD.52.2964
Abstract: Within the QCD sum-rule approach in an external field, we calculate the baryon matrix element of isovector-scalar current, $H_{\rm B}=\langle B|\overline{u}u- \overline{d}d|B\rangle/2M_{\rm B}$, for octet baryons, which appears in the response of the correlator of baryon interpolating fields to a constant isovector-scalar external field. The sum rules are obtained for a general baryon interpolating field with an appropriate form for the phenomenological ansatz of the spectral density. The key phenomenological input is the response of the quark condensates to the external field. To first order in the quark mass difference $\delta m=m_d-m_u$, the non-electromagnetic part of the baryon isospin mass splitting is given by the product of $\delta m$ and $H_{\rm B}$. Therefore, QCD sum-rule calculation of $H_{\rm B}$ leads to an estimate of the octet baryon isospin mass splittings. The resulting values are comparable to the experimental values; however, the sum-rule predictions for $H_{\rm B}$ are sensitive to the values of the response of the quark condensates to the external source, which are not well determined.
A Note on the External-Field Method in QCD Sum Rules
Xuemin Jin
Physics , 1996, DOI: 10.1103/PhysRevD.55.1693
Abstract: The external-field method has been used extensively in the QCD sum-rule approach to explore various hadron static properties. In the traditional formalism of this method, the transitions from the ground state hadron to excited states are not exponentially suppressed relative to the ground state term and thus contaminate the ground state hadron property to be extracted. In this paper, we suggest a modified formalism, in which the transition terms are exponentially suppressed relative to the ground state term. As such, the pole plus continuum spectral model, traditionally invoked in QCD sum-rule approach, can be adopted. Thus, this modified formalism has potential to improve the predictability and reliability of external-field sum-rule calculations, which is illustrated in an explicit example.
QCD sum rules for $Δ$ isobar in nuclear matter
Xuemin Jin
Physics , 1994, DOI: 10.1103/PhysRevC.51.2260
Abstract: The self-energies of $\Delta$ isobar propagating in nuclear matter are calculated using the finite-density QCD sum-rule methods. The calculations show that the Lorentz vector self-energy for the $\Delta$ is significantly smaller than the nucleon vector self-energy. The magnitude of the $\Delta$ scalar self-energy is larger than the corresponding value for the nucleon, which suggests a strong attractive net self-energy for the $\Delta$; however, the prediction for the scalar self-energy is very sensitive to the density dependence of certain in-medium four-quark condensate. Phenomenological implications for the couplings of the $\Delta$ to the nuclear scalar and vector fields are briefly discussed.
Constraints on the Fiite-Density Spectral Densities of Vector Channel
Xuemin Jin
Physics , 1994,
Abstract: Sum rules for the variation of finite-density spectral density of vector channel with baryon density are derived based on dispersion relations and the operator product expansion. These sum rules may serve as constraints on the phenomenological models for the finite-density spectral densities used in the approaches motivated from QCD. Applying these sum rules to the rho meson in nuclear medium with a simple pole-plus-continuum ansatz for the spectral densities, we found that the qualitative features of the QCD sum-rule predictions for the spectral parameters are consistent with these sum rules; however, the quantitative QCD sum-rule results violate the sum rules to certain degree.
Isospin Breaking in the Nucleon Isovector Axial Charge from QCD Sum Rules
Xuemin Jin
Physics , 1996,
Abstract: The isospin breaking in the nucleon isovector axial charge, $g_A^3$, are calculated within the external field QCD sum-rule approach. The isospin violations arising from the difference in up and down current quark masses and in up and down quark condensates are included; electromagnetic effects are not considered. We find $\delta g^3_A/g^3_A \approx (0.5-1.0)\times 10^{-2}$, where $\delta g^3_A = (g^3_A)_p + (g^3_A)_n$ and $ g^3_A = [(g^3_A)_p - (g^3_A)_n]/2$. Using the Goldberger-Treiman relation, we also obtain an estimate of the isospin breaking in the pion-nucleon coupling constant, $(g_{pp\pi_0}-g_{nn\pi_0})/g_{NN\pi} \approx (2-7) \times 10^{-3}$.
Electromagnetic Anomalies around The Wenchuan Earthquake and Their Relationship with Earthquake Preparation
Xuemin Zhang,Xuhui Shen
International Journal of Geophysics , 2011, DOI: 10.1155/2011/904132
Abstract: Electromagnetic precursors before the Wenchuan earthquake on May 12, 2008 were collected and summarized on the basis of related published papers. The relationship between electromagnetic anomalies and different earthquake preparation stages was analyzed, and an entire seismic preparation process was constructed according to corresponding anomalies in different electromagnetic parameters. It is illustrated that stereo electromagnetic observation is useful in the understanding of earthquake preparation mechanism. It is inevitable that a lot of problems exist in anomaly distinguishing and coupling mechanism analysis, which needs further studies in future.
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