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Search Results: 1 - 10 of 6619 matches for " Dengke Hou "
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Rapid and Sensitive Analysis of Eight Polyphenols in Tobacco by Rapid Resolution Liquid Chromatogarphy  [PDF]
Fuwei Xie, Ajuan Yu, Dengke Hou, Huimin Liu, Li Ding, Shusheng Zhang
American Journal of Analytical Chemistry (AJAC) , 2011, DOI: 10.4236/ajac.2011.28107
Abstract: A rapid resolution liquid chromatographic (RRLC) method for the determination of eight polyphenols in to-bacco was developed. Polyphenols were extracted from tobacco samples by methanol/ water in an ultrasonic bath, then subjected to clean up by solid phase extraction. The separation was performed on a 50 × 4.6 mm, 1.8 μm ZORBAX Eclipse XDB-C18 column. Compared with conventional HPLC method, the analysis time for eight polyphenols by RRLC method was reduced from 20 to 5 min without sacrificing resolution, and the sensitivity was improved. This method appears simple, accurate and precious. The relative standard devia-tions (RSD) of overall analysis procedure for eight tobacco polyphenols were less than 2% with the recover-ies ranging from 94% to 107%. This method could be applied to the rapid determination of major polyphe-nols in tobacco with satisfactory results.
Joint Variable Selection of Mean-Covariance Model for Longitudinal Data  [PDF]
Dengke Xu, Zhongzhan Zhang, Liucang Wu
Open Journal of Statistics (OJS) , 2013, DOI: 10.4236/ojs.2013.31004
Abstract:

In this paper we reparameterize covariance structures in longitudinal data analysis through the modified Cholesky decomposition of itself. Based on this modified Cholesky decomposition, the within-subject covariance matrix is decomposed into a unit lower triangular matrix involving moving average coefficients and a diagonal matrix involving innovation variances, which are modeled as linear functions of covariates. Then, we propose a penalized maximum likelihood method for variable selection in joint mean and covariance models based on this decomposition. Under certain regularity conditions, we establish the consistency and asymptotic normality of the penalized maximum likelihood estimators of parameters in the models. Simulation studies are undertaken to assess the finite sample performance of the proposed variable selection procedure.

Niobium alloying effect in high carbon equivalent grey cast iron
Zhou Wenbin,Zhu Hongbo,Zheng Dengke
China Foundry , 2011,
Abstract: The effect of niobium on the formation of NbC phase and solidification structure in high carbon equivalent grey cast iron was investigated. The experimental results indicated that an increase in the niobium content is favorable to refining the graphite and eutectic cell; and the pearlite lamellar spacing is reduced. Based on the thermodynamic calculation the formation of NbC is prior to the eutectic reaction. The reduction in the pearlite lamellar spacing is mainly attributed to the decrease of eutectic temperature with the addition of niobium. Additionally, properties including hardness and wear resistance were improved after the addition of niobium.
Quantum size effect in Pb(100) films: the role of symmetry and implication for film growth
Dengke Yu,Matthias Scheffler,Mats Persson
Physics , 2005, DOI: 10.1103/PhysRevB.74.113401
Abstract: We show from density-functional calculations that Pb(100) thin films exhibit quantum size effect with a bilayer periodicity in film energies, film relaxations, and work functions, which originate from different symmetry of the stacking geometry of odd and even layer films. The bilayer periodicity of the film energy is argued to survive on a semiconductor substrate, which should allow the growth of ``magically'' thick even-layer Pb(100) films. Furthermore, it is found that the quantum well states in a simple metal film can be classified into $\sigma$-bonded and $\pi$-bonded states, which quantize independently.
Lossy-to-Lossless Compression of Hyperspectral Image Using the 3D Set Partitioned Embedded ZeroBlock Coding Algorithm  [PDF]
Ying Hou
Journal of Software Engineering and Applications (JSEA) , 2009, DOI: 10.4236/jsea.2009.22013
Abstract: In this paper, we propose a three-dimensional Set Partitioned Embedded ZeroBlock Coding (3D SPEZBC) lossy-to-lossless compression algorithm for hyperspectral image which is an improved three-dimensional Embedded ZeroBlock Coding (3D EZBC) algorithm. The algorithm adopts the 3D integer wavelet packet transform proposed by Xiong et al. to decorrelate, the set-based partitioning zeroblock coding to process bitplane coding and the con-text-based adaptive arithmetic coding for further entropy coding. The theoretical analysis and experimental results demonstrate that 3D SPEZBC not only provides the same excellent compression performances as 3D EZBC, but also reduces the memory requirement compared with 3D EZBC. For achieving good coding performance, the diverse wave-let filters and unitary scaling factors are compared and evaluated, and the best choices were given. In comparison with several state-of-the-art wavelet coding algorithms, the proposed algorithm provides better compression performance and unsupervised classification accuracy.
Spectral Analysis and Variable Structural Control of an Elastic Beam  [PDF]
Xuezhang Hou
Journal of Applied Mathematics and Physics (JAMP) , 2013, DOI: 10.4236/jamp.2013.15015
Abstract:

An elastic beam system formulated by partial differential equations with initial and boundary conditions is investigated in this paper. An evolution equation corresponding with the beam system is established in an appropriate Hilbert space. The spectral analysis and semigroup generation of the system operator of the beam system are discussed. Finally, a variable structural control is proposed and a significant result that the solution of the system is exponentially stable under a variable structural control with some appropriate conditions is obtained.

Does the Pay Gap in the Top Management Team Incent Enterprise Innovation?—Based on Property Rights and Financing Constraints  [PDF]
Jingru Hou
American Journal of Industrial and Business Management (AJIBM) , 2018, DOI: 10.4236/ajibm.2018.85088
Abstract: Using the patent applications data of listed firms in China from 2005 to 2014, this paper examines how the pay gap in the top management team influences enterprise innovation. The result shows that the number of patent applications especially the number of patents for invention increases significantly when the pay gap enlarges. It means the enlargement of the pay gap in the top management team could incent executives to make innovation decisions, to promote outputs of high-quality patents for invention. Finally the quality of enterprise innovation has been improved. Especially, the incentive effect of the pay gap in the top management team is more significant in private enterprises and enterprises with strong financing constraints. Therefore, enterprises in these two groups have better innovation behaviors.
Effect of Sn addition on the glass-forming ability and mechanical properties of Ni-Nb-Zr bulk metallic glasses
DengKe Li,HaiFeng Zhang,AiMin Wang,ZhengWang Zhu,ZhuangQi Hu
Chinese Science Bulletin , 2011, DOI: 10.1007/s11434-011-4763-x
Abstract: The effect of tin (Sn) addition on the glass forming ability (GFA) and mechanical properties of the Ni-Nb-Zr ternary alloy system has been studied. The addition of Sn improves the GFA; Ni61Nb35.5 x Zr3.5Sn x (in at.%) alloys with x=1 can be cast into amorphous samples at least 3 mm in diameter using a copper mold injection-casting method. The critical size for glass formation decreases to 2 mm when x=5 because Ni2SnZr phase precipitates readily. The addition of Sn is also effective in enhancing the stability of the supercooled liquid; a maximum supercooled liquid region of 48 K was attained for the Ni61Nb30.5Zr3.5Sn5 alloy. Compression tests reveal that the Ni61Nb33.5Zr3.5Sn2 alloy possesses the best mechanical properties, with yield strength ~3180 MPa, fracture strength ~3390 MPa and plastic strain ~1.3%. The fracture surfaces examined by scanning electron microscopy indicate that the alloys have a transition from ductility to brittleness in fracture behavior. The combination of high GFA, high thermal stability, high strength and compressive plasticity makes these alloys potentially attractive for engineering applications.
Hypertensive nephropathy treatment by heart-protecting musk pill: a study of anti-inflammatory therapy for target organ damage of hypertension
Dengke Tian, Shuang Ling, Gangling Chen, et al
International Journal of General Medicine , 2011, DOI: http://dx.doi.org/10.2147/IJGM.S15235
Abstract: tensive nephropathy treatment by heart-protecting musk pill: a study of anti-inflammatory therapy for target organ damage of hypertension Original Research (3258) Total Article Views Authors: Dengke Tian, Shuang Ling, Gangling Chen, et al Published Date February 2011 Volume 2011:4 Pages 131 - 139 DOI: http://dx.doi.org/10.2147/IJGM.S15235 Dengke Tian1, Shuang Ling1, Gangling Chen1, Yajuan Li1, Jun Liu1, Murad Ferid1,2, Ka Bian1,2 1Murad Research Institute for Modernized Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, PR, China; 2Department of Integrative Biology and Pharmacology, Institute of Molecular Medicine, University of Texas Medical School, Houston, TX, USA Abstract: This study was designed to investigate the protective effect of the heart-protecting musk pill (HMP) on inflammatory injury of kidney from spontaneously hypertensive rat (SHR). Male SHRs aged 4 weeks were divided into SHR model group, HMP low-dosage group (13.5 mg/kg), and HMP high-dosage group (40 mg/kg). Age-matched Wistar–Kyoto rats were used as normal control. All rats were killed at 12 weeks of age. Tail-cuff method and enzyme-linked immunosorbent assay were used to determine rat systolic blood pressure and angiotensin II (Ang II) contents, respectively. Renal inflammatory damage was evaluated by the following parameters: protein expressions of inflammatory cytokines, carbonyl protein contents, nitrite concentration, infiltration of monocytes/macrophages in interstitium and glomeruli, kidney pathological changes, and excretion rate of urinary protein. HMP did not prevent the development of hypertension in SHR. However, this Chinese medicinal compound decreased renal Ang II content. Consistent with the change of renal Ang II, all the parameters of renal inflammatory injury were significantly decreased by HMP. This study indicates that HMP is a potent suppressor of renal inflammatory damage in SHR, which may serve as a basis for the advanced preventive and therapeutic investigation of HMP in hypertensive nephropathy.
A COUPLED ELASTOPLASTIC DAMAGE MODEL FOR GAS-SATURATED COAL
含瓦斯煤岩耦合弹塑性损伤本构模型研究

YIN Guangzhi,WANG Dengke,
尹光志
,王登科

岩石力学与工程学报 , 2009,
Abstract: 三维压缩条件下,随着载荷的逐渐增加,岩石类材料内部微裂纹的传播与错动不断加剧,最终导致非线性应力-应变关系、弹性模量的减小、变形的各向异性、体积膨胀以及不可逆塑性变形等结果.这些现象可以利用连续损伤力学及塑性理论来描述.首先为考虑瓦斯吸附对煤岩的影响,在多孔介质有效应力原理中引入瓦斯吸附的膨胀应力,得出适用于含瓦斯煤岩的有效应力计算公式.通过引入与塑性屈服准则相关联的各向异性损伤因子和损伤准则来描述含瓦斯煤岩的塑性变形及损伤演化过程.利用不可逆热力学原理,对含瓦斯煤岩的损伤演化规律及塑性变形与损伤之间的耦合效应进行有效描述.根据实验结果,采用非关联塑性流动法则,建立能反映各种应力条件下力学行为的含瓦斯煤岩耦合弹塑性损伤本构模型.通过理论与实验结果的比较发现,所提出的耦合弹塑性损伤本构模型能真实有效地描述含瓦斯煤岩在不同应力条件下的力学特性;同时,该模型还适用于其他岩石类材料的本构描述.
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