ATSP:时态网络可视化的自适应时间片划分方法

现有的时态网络可视化方法大多采用等量时间片来可视化网络的演变;不利于时态模式的快速挖掘和发现。为此;根据时态网络固有的特征提出自适应时间片划分方法（Adaptive Time Slice Partition method;ATSP）。在时态网络的两种表示方式（基于事件的表示方式和基于快照的表示方式）的基础上;构建了ATSP的基础模型;同时提出了一种改进模型用来描述事件间隔时间服从长尾分布的时态网络。为了实现时间片的不等量划分;针对探索任务的不同提出了基于时态模式的ATSP规则和基于中心节点的ATSP规则;并提出了实现算法——层次划分算法（Hierarchical Partition algorithm;HP）和增量划分算法（Incremental Partition algorithm;IP）。实验结果表明;ATSP方法比传统的时间片划分方法更能准确地表示网络的时态特征;且该方法应用于可视化时;能有效归纳并展示网络的特征;明显提高了视觉分析的效率。     

Effect of high-voltage electrostatic field on quality of carrot juice during refrigeration

In the present study, carrot juice was used as the experimental material and stored in a 100 kV/m high-voltage electrostatic field (HVEF; E-group) which was used as a freshness-retention system. The changes in the biological properties were investigated relative to those juices which were stored in a common refrigerator (R-group) and controlled at the same temperature (4 °C). The results showed that the extent of color difference (ΔE), amount of total phenolics, tannins, and total plate counts of carrot juice were increased during the storage period, whereas the turbidity and amount of total carotenoids decreased under all treatment conditions. These factors remained relatively constant during storage in the E-group, whereas a significant difference (p < 0.05) was observed in the R-group. The HVEF treatment yielded better physicochemical properties and prolonged the shelf-life of the carrot juice. The application of HVEF at low temperature has the potential of imparting freshness and a high nutritional value to the products.     

储层预测技术在QK17-2油田水平井钻探中的应用

利用钻井、测井数据和地震资料制作合成地震记录 ,确定含油砂岩顶面为强振幅反射的波峰 ;应用三维相干分析精确解释断裂发育及分布规律 ;通过顺层振幅切片和三维可视化技术精确描述砂层组的空间展布 ;测井约束波阻抗反演提高了地震分辨率 ,在此基础上 ,进一步描述出单砂体的形态、厚度及物性的横向变化 ;为大位移水平井提供了准确的着陆点 ,并随时指导水平井钻进 ,使渤海海域首次进行的大位移水平井钻井获得成功     

The effect of osmotic dehydrofreezing on the role of the cell membrane in carrot texture softening after freeze-thawing

To understand the protective mechanism of the osmotic dehydrofreezing technique on carrot texture after freeze-thawing, two mechanical texture parameters, fracture stress related to the cell wall and initial modulus related to the cell membrane, as well as cell membrane water permeability using PFG-NMR were evaluated. In particular, to understand the role of the cell membrane in texture alteration, tissue in which the cell membrane was exposed to chloroform vapor was used. Although dehydrofreezing protected texture from freezing damage, the effect was only observed with respect to fracture stress, with exhibited values close to those for raw tissue. However, there was no protective effect on initial modulus and water permeability, in which values did not differ from those of cell membrane-free tissue. More specifically, osmotic dehydrofreezing had no effect on the cell membrane induced by freeze-thawing.     

A simple UV-Vis spectrophotometric method for determination of β-carotene content in raw carrot, sweet potato and supplemented chicken meat nuggets

A simple, rapid and low cost analytical method for the determination of β-carotene content in four different food categories is developed and validated. This method is based on solvent extraction followed by UV-Vis spectrometric detection. Target compound was extracted with four different solvents, in which acetone appears to be an excellent extractant as recovery of the analyte at 1 μg/g concentration in spiked samples was in the range of 67.8-98.8%, with relative standard deviation (RSD) ranging between 4.8 and 6.6%. Intra- and inter-day assay precisions of the method at 0.1, 1.0 and 5.0 μg/g concentrations ranged in between 3.4 and 8.9%. The linearities for β- carotene in the pure acetone, raw carrot, sweet potato, and fortified raw and cooked chicken meat nuggets were 0.994, 0.995, 0.990, 0.984 and 0.984, respectively. For robustness, the analytical method was applied to 24 samples of four different food categories namely carrot, sweet potato and carrot and sweet potato supplemented chicken meat nuggets.     

Vacuum frying reduces oil uptake and improves the quality parameters of carrot crisps

Recent consumer trends towards healthier and low fat products have had a significant impact on the snack industry. The objective of this study was to examine the most important quality parameters of vacuum and atmospheric fried carrot slices in order to identify the specific advantages of vacuum technology. Said parameters include oil uptake, colour changes, and trans α and β-carotene degradation. Equivalent thermal driving forces were used (ΔT = 60 °C and 80 °C) to compare the processes, maintaining a constant difference in temperature between the oil and the boiling point of water at the working pressure. The results showed that vacuum frying can reduce oil content by nearly 50% (d.b.) and preserve approximately 90% of trans α-carotene and 86% of trans β-carotene. This process also allowed for the raw carrot colour to be preserved, which was reflected by good correlations between a∗ and trans β-carotene content, b∗ and trans α-carotene content, and hue and total carotenoid content.     

Effect of Pulsed Electric Field and Osmotic Dehydration Pretreatment on the Convective Drying of Carrot Tissue

The influence of pulsed electric field (PEF) and subsequent centrifugal osmotic dehydration (OD) on the convective drying behavior of carrot is investigated. The PEF was carried out at an intensity of E = 0.60 kV/cm and a treatment duration of t_PEF = 50 ms. The following centrifugal OD was performed in a sucrose solution of 65% (w/w) at 40°C for 0, 1, 2, or 4 h under 2400 × g. The drying was performed after the centrifugal OD for temperatures 40-60°C and at constant air rate (6 m³/h).

With the increase of OD duration the air drying time is reduced spectacularly. The dimensionless moisture ratio Xr = 0.1 is reached for PEF-untreated carrots after 370 min of air drying at 60°C in absence of centrifugal OD against 90 min of air drying after the 240 min of centrifugal OD. The PEF treatment reduces additionally the air drying time. The total time of dehydration operations can be shortened when OD time is optimized. For instance, the minimal time required to dehydrate untreated carrots until Xr = 0.1 is 260 min (120 min of OD at 40°C and 140 min of drying at 60°C). It is reduced to 230 min with PEF-treated carrots.

The moisture effective diffusivity D_eff is calculated for the convective air drying based on Fick's law. The centrifugal OD pretreatment increases drastically the value of D_eff. For instance, 4 h of centrifugal OD permitted increasing the value of D_eff from 0.93 · 10^-9 to 3.85 · 10^-9 m²/s for untreated carrots and from 1.17 · 10^-9 to 5.10 · 10^-9 m²/s for PEF-treated carrots.