INFLUENCE OF PHASE RATIO ON PACKING EFFICIENCY IN COLUMNS FOR MASS TRANSFER PROCESSES

The phase ratio has been found to affect the packing efficiency in packed columns.To ac-count for the effect,a model is set up to correlate the height of a mass transfer unit with the phaseratio with reasonable accuracy.Proposed also is a correlation that allows to predict the efficiency inquestion at any given liquid-gas ratio using the knowledge of other efficiency values at other liquid-gas ratios.

Influence of MgO/MgCl_2 Molar Ratio on Phase Stability of Magnesium Oxychloride Cement

Formation, solution and phase change of hydration products in MgO-MgCl2-H2O system was studied with thermodynamics method, and resistance to water immersion and phase change of magnesium oxychloride cement with different MgO/MgCl2 molar ratio was experimented. The results show that pH value of immersion solution of cement paste has a remarkable influence on phase stability of hydration products. A higher pH value leads to a lower solubility and a better phase stability of hydration products. When the solution pH value is higher than 10.37, the precipitation of much Mg（OH）2 crystal induces a worse phase stability of hydration products. With the increasing MgO/MgCl2 molar ratio （lower than 6）, the more amount of MgO in the hydration products enhances the alkalinity of solution and the phase stability is improved. However, when the MgO/MgCl2 molar ratio is higher than 6 and the excessive MgO exsits in the hydration products, the cement paste may be damaged by the excessive crystallization stress of a great deal of Mg（OH）2 formation.

MULTI-PEAK MATCH INTENSITY RATIO METHOD OF QUANTI-TATIVE X-RAY DIFFRACTION PHASE ANALYSIS

A new method for quantitative phase analysis is proposed by using X-ray diffraction multi-peak match intensity ratio. This method can obtain the multi-peak match intensity ratio among each phase in the mixture sample by using all diffraction peak data in the mixture sample X-ray diffraction spectrum and combining the relative intensity distribution data of each phase standard peak in JCPDS card to carry on the least square method regression analysis. It is benefit to improve the precision of quantitative phase analysis that the given single line ratio which is usually adopted is taken the place of the multi-peak match intensity ratio and is used in X-ray diffraction quantitative phase analysis of the mixture sample. By analyzing four-group mixture sample, adopting multi-peak match intensity ratio and X-ray diffraction quantitative phase analysis principle of combining the adiabatic and matrix flushing method, it is tested that the experimental results are identical with theory.

Effect of Starch/Polylactic Acid Ratio on the Interdependence of Two-Phase and the Properties of Composites

Starch/polylactic acid(PLA) composites were prepared by melt extrusion, with corn starch and PLA as raw materials, glycerol as the plasticizer. Effects of starch/PLA ratio on the interdependence of two-phase and other properties of the composites were studied. The combination of results of TGA with SEM indicated that the interdependence between starch and PLA was increased gradually as the starch/PLA ratio reduced. DSC results showed that the glass transition temperature(Tg), melting temperature(Tm) and degree of crystallinity of PLA in composites were increased gradually, whereas the cold crystallization temperature(Tc) was gradually decreased as the starch/PLA ratio reduced. The rheological properties of composites were closely related with the interdependence of two-phase, with reducing starch/PLA proportion, the interdependence was increased, and then the strain for storage modulus was firstl reduced and then gradually increased. Frequency scanning showed that the storage modulus and complex viscosity were decreased with reducing starch content. As the starch/PLA ratio reduced, the matrix phase PLA was increased, so that the strength of composites was increased gradually, whereas water absorption rate was decreased gradually.

Effects of Volume Ratios of Water Phase to Oily Phase on Morphology and Releasing Performance of Emulsion Electrospun Fibers

Emulsion electrospinning as a novel process in spinning core-sheath fibers shows a promising potential in drug release control. The volume ratio of water phase to oily phase is one of the critical parameters in forming core-sheath fibers. In this study, water phase was presented by hydrophilic tetracycline hydrochloride and oily phase by hydrophobic poly （E-caprolactone） （PCL）. The effects of volume ratios of water phase to oily phase on fiber morphology and in vitro drug release were investigated. Scanning electron microscopy （ SEM ）, transmission electron microscopy （ TEM）, and eonfoeal laser scanning microscopy（CLSM） were used to observe the morphology, core.sheath structure of the fibers and drug loading in the fibers, respectively. Samples of three different volume ratios of water phase to oily phase, 1： 25, 1：15, and 1：10, were prepared with the same concentration of drug solution. Experiment results showed that, with an increase in the volume ratios of water phase to oily phase, the fiber diameter increased and diameter distribution scattered. The drug entrapment efficiency of the fibers reduces with the increase in volume ratios, L e. , from 73.48 % in the ratio of 1 ： 25, 62.23 % in 1 ： 15, down to 45.63 % in 1：10. In vitro release tests showed that a higher volume ratio of water phase to oily phase would lead to a lower release rate resulted from thicker fiber sheath.

Arrival time measurements of first arrival phases P and PKIKP using the method of fixed scale wavelet transformation ratio

The arrival times of first teleseismic phases are difficult to be measured precisely because of slowly and gradually changed onsets and weak amplitudes. The arrival times measured manually are usually behind the real ones. In this paper, using the ratio method of fixed scale wavelet transformations improved by us, the arrival times for the first arrival phases (such as P and PKIKP) at the teleseismic and far-teleseismic distances were measured. The results are reasonable and reliable based on the analysis and discussion of the reliabilities and errors.

Physical meaning and prediction efficiency of the load/unload response ratio of rocks in strain-weakening phase before failure

Rock experiment results indicate that the load/unload response ratio (LURR) of rocks expressed via strain energy may have singular or negative value after the stress in the rock reaches its maximum before rock failure or when the rock goes into the strain-weakening phase. The universality of this phenomenon is discussed. Expressed via strain or strain energy and the travel time of P wave, the variation form of the reciprocal of LURR during the process of rock failure preparation is derived. The results show that after a sharp decrease the reciprocal of LURR reaches its minimum when the main fracture of the rock is about to appear. This feature can be taken as an indication that the rock main fracture is impending.

Amplitude Ratio of Regional Seismic Phases: An Efficient Indicator of Thermal State of the Lithosphere

By analyzing seismograms of short period records at the Beijing SeismoJogicaJ Observatory, the present paper investigates the amplitude ratio of seismic phases. The results indicate that the amplitude ratio of Sn/Lg is correlated with the lithosphere structure, the thermal state, and strong earthquake occurrence in the region the seismic rays pass through. The significance of such a correlation in the study on the genesis and prediction of strong earthquakes is discussed.

A PHASE SCRAMBLING SCHEME FOR SUPPRESSION OF PEAK TO AVERAGE POWER RATIO FOR OFDM

The complex-valued modulating vectors for the subcarriers consist of two kinds of components: One is the information-bearing components superposed with pseudo-randomized phases and the other is the suppression components with specified scrambling phases. The pseudo randomized phases are generated according to the predefined polynomial and mapping function whereas the scrambling phases are from a gradient algorithm. The simulation results verify the rationality and validity of the phase scrambling.

Phase-Space Areas of the Body Motion in the Solar System Deduced from the Bohr-Sommerfeld Atomic Theory and Approximate Invariance of Their Ratios for the Pairs of Planets and Satellites

Energy-time and momentum-position phase spaces defined by the electron orbits in the hydrogen-like atom exhibit special properties of equivalence. It is demonstrated that equivalence of the same kind can be obtained for the phase-space areas defined by the orbit pairs of planets, or satellites, which compose the solar system. In the choice of the examined areas it is useful to be guided by the Bohr-Sommerfeld atomic theory.

Signal-to-noise ratio comparison of angular signal radiography and phase stepping method

Grating-based x-ray phase contrast imaging has the potential to be applied in future medical applications as it is compatible with both laboratory and synchrotron source. However, information retrieval methods are important because acquisition speed, scanning mode, image quality, and radiation dose depend on them. Phase-stepping （PS） is a widely used method to retrieve information, while angular signal radiography （ASR） is a newly established method. In this manuscript, signal-to-noise ratios （SNRs） of ASR are compared with that of PS. Numerical experiments are performed to validate theoretical results. SNRs comparison shows that for refraction and scattering images ASR has higher SNR than PS method, while for absorption image both methods have same SNR. Therefore, our conclusions would have guideline in future preclinical and clinical applications.

PARAMETERS DETERMINATION METHOD OF PHASE-SPACE RECONSTRUCTION BASED ON DIFFERENTIAL ENTROPY RATIO AND RBF NEURAL NETWORK

Phase space reconstruction is the first step of recognizing the chaotic time series.On the basis of differential entropy ratio method,the embedding dimension opt m and time delay t are optimal for the state space reconstruction could be determined.But they are not the optimal parameters accepted for prediction.This study proposes an improved method based on the differential entropy ratio and Radial Basis Function(RBF)neural network to estimate the embedding dimension m and the time delay t,which have both optimal characteristics of the state space reconstruction and the prediction.Simulating experiments of Lorenz system and Doffing system show that the original phase space could be reconstructed from the time series effectively,and both the prediction accuracy and prediction length are improved greatly.

Ratio-Cum-Product Estimator Using Multiple Auxiliary Attributes in Single Phase Sampling

In this paper, we have proposed a class of ratio-cum-product estimator for estimating population mean of study variable for single phase sampling using multi-auxiliary attributes. The expressions for mean square error are derived. An empirical study is given to compare the performance of the estimator with existing estimators. It has been found that the ratio-cum-product estimator using multiple auxiliary attributes is more efficient than mean per unit, product and ratio estimators using one auxiliary attribute, and Product and Ratio estimators using multiple auxiliary attributes in single phase sampling.

Mixture Regression-Cum-Ratio Estimator Using Multi-Auxiliary Variables and Attributes in Single-Phase Sampling

In this paper, we have proposed a class of mixture regression-cum-ratio estimator for estimating population mean by using information on multiple auxiliary variables and attributes simultaneously in single-phase sampling and analyzed the properties of the estimator. An empirical was carried out to compare the performance of the proposed estimator with the existing estimators of finite population mean using simulated population. It was found that the mixture regression-cum-ratio estimator was more efficient than ratio and regression estimators using one auxiliary variable and attribute, ratio and regression estimators using multiple auxiliary variables and attributes and regression-cum-ratio estimators using multiple auxiliary variables and attributes in single-phase sampling for finite population.

仿枪虾虾螯纵向混合负泊松比结构设计与耐撞性研究

为提高汽车安全防护结构耐撞性,以枪虾虾螯(大螯)作为仿生原型,通过生物实验提取虾螯微观结构,设计了24种仿生混合负泊松比吸能结构。以质量比吸能(SEA)、结构平均压溃效率(CFE)、初始峰值载荷(IPF)作为评价结构耐撞性的主要指标,借助经过验证的有限元模型对设计结构仿真模拟,经过结果数据分析确定影响结构耐撞性指标的关键参数a(胞元内凹深度),结合实际工况利用加权组合综合评价方法选出最优耐撞性结构。结果显示,当a=6.80 mm时的BCDA型混合结构耐撞性能最优,优化后SEA=3.21 kJ/kg,IPF=8.58 kN,CFE=31.29%。与单一胞元结构相比,优化后混合模型IPF最高降低35.24%,SEA最高提升35.72%,CFE有所下降,最多降低47.20%。

Generalized Ratio-Cum-Product Estimators for Two-Phase Sampling Using Multi-Auxiliary Variables

In this paper, we have proposed estimators of finite population mean using generalized Ratio- cum-product estimator for two-Phase sampling using multi-auxiliary variables under full, partial and no information cases and investigated their finite sample properties. An empirical study is given to compare the performance of the proposed estimators with the existing estimators that utilize auxiliary variable(s) for finite population mean. It has been found that the generalized Ra-tio-cum-product estimator in full information case using multiple auxiliary variables is more efficient than mean per unit, ratio and product estimator using one auxiliary variable, ratio and product estimator using multiple auxiliary variable and ratio-cum-product estimators in both partial and no information case in two phase sampling. A generalized Ratio-cum-product estimator in partial information case is more efficient than Generalized Ratio-cum-product estimator in No information case.

非均相体系在微通道中的封堵性能研究

基于大庆油田天然岩心孔隙尺度分布特征建立了微通道模型,考虑非均相体系中的分散相和连续相的变形及流动特征,以相场法建立流动模型并用有限元方法求解,模拟了分散相颗粒在微通道内的生成,并实现了颗粒分选,研究了微观孔喉结构中匹配系数和孔喉比对颗粒封堵性能的影响。结果表明,颗粒在微观孔喉结构中发生弹性封堵时,孔喉入口处压力随颗粒运移通过而呈现周期性变化;颗粒与孔喉最佳匹配系数为[1.0,1.4),此区间内颗粒能够在孔喉入口处暂时封堵,变形运移通过孔喉后恢复原形;当孔隙直径相同时,匹配系数和孔喉比越大,颗粒通过压力越大;颗粒粒径越大,颗粒通过压力临界值越小。

Ratio-Cum-Product Estimator Using Multiple Auxiliary Attributes in Two-Phase Sampling

In this paper, we have proposed three classes of ratio-cum-product estimators for estimating population mean of study variable for two-phase sampling using multi-auxiliary attributes for full information, partial information and no information cases. The expressions for mean square errors are derived. An empirical study is given to compare the performance of the estimator with the existing estimator that utilizes auxiliary attribute or multiple auxiliary attributes. The ratio-cum-product estimator in two-phase sampling for full information case has been found to be more efficient than existing estimators and also ratio-cum-product estimator in two-phase sampling for both partial and no information case. Finally, ratio-cum-product estimator in two-phase sampling for partial information case has been found to be more efficient than ratio-cum-product estimator in two-phase sampling for no information case.

Mixture Ratio Estimators Using Multi-Auxiliary Variables and Attributes for Two-Phase Sampling

In this paper, we have proposed three classes of mixture ratio estimators for estimating population mean by using information on auxiliary variables and attributes simultaneously in two-phase sampling under full, partial and no information cases and analyzed the properties of the estimators. A simulated study was carried out to compare the performance of the proposed estimators with the existing estimators of finite population mean. It has been found that the mixture ratio estimator in full information case using multiple auxiliary variables and attributes is more efficient than mean per unit, ratio estimator using one auxiliary variable and one attribute, ratio estimator using multiple auxiliary variable and multiple auxiliary attributes and mixture ratio estimators in both partial and no information case in two-phase sampling. A mixture ratio estimator in partial information case is more efficient than mixture ratio estimators in no information case.

相变腔冷凝现象对沸腾-凝结共存相变传热的影响

针对平板热管均热器内部狭小空间存在着强烈的沸腾与凝结相互作用,以去离子水为工质,可视化实验研究了冷凝面上发生的凝结现象及其对相变腔传热性能的影响。通过分析冷凝面上液滴的形成、长大、汇聚成液膜、滴落,以及气液界面产生气泡随气流运动对冷凝液膜的冲刷作用,揭示了不同热流密度和充液率时相变腔冷凝面传热传质特性对沸腾-凝结共存相变传热影响的内在机理。实验结果表明:受重力影响,水蒸气在冷凝面上凝结有液滴和液膜共存并相互转化的特性,冷凝面热阻在相变腔总热阻中占比65%~88%,适宜的充液率有利于沸腾气泡冲刷冷凝壁面,加快冷凝液的回流,改善冷凝面及相变腔的传热性能;随着热流密度的增大,沸腾过程变得剧烈,冷凝面受沸腾气泡的冲刷频率提高,冷凝液回流速度加快,冷凝面热阻减小,传热性能得到提高。