各向同性压缩过程中圆盘体系的基本性质

结合理论分析与数值模拟研究仅有线性排斥力的二维无序圆盘体系在准静态各向同性压缩过程中的基本性质.引入平均约化重叠量、约化压强等概念,基于微观的力学分析,导出约化压强与体系的组成成分、几何统计量及形变统计量之间的关系.基于数值模拟结果,讨论平均接触数增量、各种接触类型的百分比、平均约化重叠量、约化压强等物理量在大范围压缩的过程中随体积分数增量的变化,给出一个形式简洁的近似约化压强公式.模拟结果表明圆盘体系在远离临界阻塞态及接近临界阻塞态时的压缩响应不同.     

Search for ψ(4S) → ηJ/ψ in B~±→ ηJ/ψK~± and e~+e~-→ ηJ/ψ processes

We search for the ψ(4S) state in the B~±→ηJ/ψK~± and e~+e~-→ηJ/ψ processes based on the Belle measurements with the assumed mass M =(4230±8) MeV/c~2 and width Γ =(38±12) MeV. No significant signal is observed in the ηJ/ψ mass spectra. The 90% confidence level upper limit on the product branching fraction B(B~±→ψ(4S)K~±)B(ψ(4S)→ηJ/ψ) 6.8×10~(-6) is obtained in the B~±→ηJ/ψK~± decays. By assuming the partial width of ψ(4S)→e~+e~-to be 0.63 ke V, a branching fraction limitB(ψ(4S)→ηJ/ψ) 1.3% is obtained at the 90%confidence level in e~+e~-→ηJ/ψ, which is consistent with the theoretical prediction.     

Interfacial area concentration in gas–liquid bubbly to churn flow regimes in large diameter pipes

This study performed a survey on existing correlations for interfacial area concentration (IAC) prediction and collected an IAC experimental database of two-phase flows taken under various flow conditions in large diameter pipes. Although some of these existing correlations were developed by partly using the IAC databases taken in the low-void-fraction two-phase flows in large diameter pipes, no correlation can satisfactorily predict the IAC in the two-phase flows changing from bubbly, cap bubbly to churn flow in the collected database of large diameter pipes. So this study presented a systematic way to predict the IAC for the bubbly-to-churn flows in large diameter pipes by categorizing bubbles into two groups (group 1: spherical or distorted bubble, group 2: cap bubble). A correlation was developed to predict the group 1 void fraction by using the void fraction for all bubble. The group 1 bubble IAC and bubble diameter were modeled by using the key parameters such as group 1 void fraction and bubble Reynolds number based on the analysis of Hibiki and Ishii (2001, 2002) using one-dimensional bubble number density and interfacial area transport equations. The correlations of IAC and bubble diameter for group 2 cap bubbles were developed by taking into account the characteristics of the representative bubbles among the group 2 bubbles and the comparison between a newly-derived drift velocity correlation for large diameter pipes and the existing drift velocity correlation of Kataoka and Ishii (1987) for large diameter pipes. The predictions from the newly-developed two-group IAC correlation were compared with the collected experimental data in gas–liquid bubbly to churn flow regimes in large diameter pipes and their mean absolute relative deviations were obtained to be 28.1%, 54.4% and 29.6% for group 1, group 2 and all bubbles respectively.     

Mechanistic investigation into particulate matter formation during air and oxyfuel combustion of formulated water-soluble fractions of bio-oil

This paper reports a systematic study on the formation of particulate matter with diameter of <10 µm (i.e., PM₁₀) during the combustion of two formulated water-soluble fractions (FWSFs) of bio-oil in a drop-tube-furnace (DTF) at 1400 °C under air or oxyfuel (30%O₂/70%CO₂) conditions. FWSF-1 was an organic-free calcium chloride solution with a calcium concentration similar to that in the bio-oil. FWSF-2 was formulated from the compositions of major organics in bio-oil WSF, doped with calcium chloride at the same concentration. The results suggest that similar to bio-oil combustion, the FWSF combustion produces mainly particulate matter with diameter of between 0.1 and 10 µm (i.e., PM_0.1–10). Since there are no combustibles in the organic-free FWSF-1, the PM is produced via droplet evaporation followed by crystallization, fusion and further reactions to form CaO (in air or argon) or partially CaCO₃ (under oxyfuel condition). With the addition of organics, FWSF-2 combustion produces PM₁₀ shifting to smaller sizes due to extensive break up of droplets via microexplosion. Sprays with larger droplet size produce PM₁₀ with increased sizes. The results show that upon cooling CaO produced during combustion in air can react with HCl gas to form CaCl₂ in PM_0.1. The predicted PSDs of PM₁₀ based on the assumption that one droplet produces one PM particle is considerably larger than experimentally-measured PSDs of PM₁₀ during the combustion of FWSFs, confirming that breakup of spray droplets takes place and such breakup is extensive for FWSF-2 when organics are present in the fuel.     

基于滑速比的气水两相流气相流量计算方法研究

目前对气水两相流的分相流量的研究中,多是针对两相流总流量和液相分相流量进行,对气相分相流量的研究很少.本文利用文丘里管和含气率传感器对空气水两相流气相流量计算方法进行了研究,在均相流模型基础上考虑了滑速比因素造成的影响,探讨了两相流气相流量计算方法.结果表明,该方法相对于传统的均相流模型在计算精度上得到了显著提高.     

A New Higher Order Shear Deformation Model for Static Behavior of Functionally Graded Plates

In this paper, a new displacement based high-order shear deformation theory is introduced for the static response of functionally graded plate. Unlike any other theory, the number of unknown functions involved is only four, as against five in case of other shear deformation theories. The theory presented is variationally consistent, has strong similarity with classical plate theory in many aspects, does not require shear correction factor, and gives rise to transverse shear stress variation such that the transverse shear stresses vary parabolically across the thickness satisfying shear stress free surface conditions. The mechanical properties of the plate are assumed to vary continuously in the thickness direction by a simple power-law distribution in terms of the volume fractions of the constituents. Numerical illustrations concerned flexural behavior of FG plates with Metal-Ceramic composition. Parametric studies are performed for varying ceramic volume fraction, volume fraction profiles, aspect ratios and length to thickness ratios. The validity of the present theory is investigated by comparing some of the present results with those of the classical, the first-order and the other higher-order theories. It can be concluded that the proposed theory is accurate and simple in solving the static behavior of functionally graded plates.     

Hydrodynamic behavior of an internally circulating fluidized bed with tubular gas distributors

To better understand the hydrodynamic behavior of an internally circulating fluidized bed, solids holdup in the down-comer （Eso）, solids circulation rate （Gs） and gas bypassing fraction （from down-comer to riser y~R, and from riser to down-comer yRD） were experimentally studied. The effects of gas velocities in the riser and in the down-comer （UR and UD）, orifice diameter in the draft tube （dor）, and draft tube height （HR） were investigated. Experimental results showed that increase of gas velocities led to increase in Gs and yDR, and slight decrease in yeD. Larger orifice diameter on the draft tube led to higher 8sD, Gs and yDR, but had insignificant influence on YRD. with increasing draft tube height, both Gs and YDR first increased and then decreased, while yRD first decreased and then increased. Proposed correlations for predicting the hydrodynamic parameters agreed reasonably well with experimental values.     

人肝癌SMMC-7721细胞对低剂量γ射线辐射超敏感性的研究

研究了人肝癌细胞SMMC-7721在低剂量γ射线照射下超敏感性和增强的辐射抗性响应。选用对数生长期细胞接受0—6 Gy不同剂量的^60Coγ射线的照射。利用流式细胞仪对细胞进行分选计数,并用克隆形成法检测细胞存活率。发现SMMC-7721细胞存在低剂量辐射超敏感性和增强的辐射抗性响应,即在0—0．3Gy之间细胞表现出单位剂量杀伤增强现象,在0．3—1Gy细胞表现一定的辐射抗性,在1Gy以上,细胞的存活符合线性平方模型。     

柠檬桉叶挥发性成分的提取及成分分析

采用水蒸气蒸馏法从柠檬桉叶中提取挥发油中的油相成分,用乙醚作为溶剂从蒸馏残液中萃取挥发油中的水溶性物质,利用气相色谱-质谱联用(GC-MS)分析二者的化学成分并进行比较。柠檬桉叶挥发油油相成分的得油率为1.36%(以鲜重计),确认了其中的37种成分,占油相成分总量的97.36%,其中有12种碳氢化合物和25种含氧化合物,其主要成分为香茅醛(57.00%),其后依次是香茅醇(15.89%)、乙酸香茅酯(15.33%)。水溶性成分的得油率为0.48%(以鲜重计),确认了其中的10种成分,占水溶性物质总量的82.05%,主要为醇类物质,其主要成分为顺-对烷-3,8-二醇(53.43%)和反-对烷-3,8-二醇(16.48%)。     

色谱与色谱/质谱法相结合分析热裂解汽油C9馏分

采用毛细管气相色谱-氢火焰离子化检测器（CGC-FID）和气相色谱-质谱法(GC/MS)分析了热裂解汽油C9 馏分的组成。实验使用PONA毛细管气相色谱柱(100 m×0.25 mm i.d.×0.5 μm),根据烃类化合物在PONA柱上的保留规律,以正构烷烃标样保留值作为碳数分布依据,定量分析了裂解汽油C9 馏分中烃类化合物的碳数分布和单体烃含量;用GC/MS联用技术和CGC保留值定性法相结合对裂解汽油C9 馏分中相对含量大于0.2%的39种化合物进行了定性。