高压交变电场对稻谷储藏品质和加工品质影响

目的 以粮库收储当年的粳稻为研究对象,研究高压交变电场和充氮气调环境中稻谷储藏品质和加工品质特征,旨在初步探讨高压交变电场在稻谷储藏中的应用.方法 采用双因素两水平实验,在28℃下,在空气无电场、空气有电场、充氮气调无电场和充氮气调电场这4个处理环境中对稻谷进行储藏,探讨其品质变化.结果 充氮气调处理对储藏稻谷的水分含量下降,脂肪酸值、黄粒米率、黄度指数和碎米率的上升有显著减缓作用;高压交变电场储藏对稻谷脂肪酸值、黄粒米率、黄度指数和碎米率的上升有显著抑制作用,脂肪酸值和黄变抑制效果相较于充氮气调处理均有不同程度的提高.另外研究表明,电场和气调处理对糙米率和精米率均没有显著影响.结论 在高压交变电场和充氮气调处理环境中储藏稻谷都能起到较好的保质作用,电场处理对于抑制脂肪酸值和黄变有一定优势,这为高压交变电场仓储稻谷的推广应用提供了技术指导.     

提取剂损耗对稻谷脂肪酸值测定结果影响的研究

为探讨提取剂损耗对稻谷脂肪酸值测定结果是否有显著影响,本文进行了两种检测方法的对照实验,研究发现:用GB/T 20569-2006《稻谷储存品质判定规则》测定稻谷脂肪酸值时,提取剂损耗对测定结果有不容忽视的显著影响,影响程度主要取决于提取剂的损耗程度以及样品中游离脂肪酸的含量;目前测定标准GB/T 20569-2006中沿用的稀释倍数是否合理值得商榷;该检测项目最好能引入修正因子f,以校正提取剂损耗所带来的影响,此次实验获得的f为0.89,适用于脂肪酸值测定结果在20mg/100g左右的样品。     

微波消解ICP-MS测定稻谷中镉含量

本文讲述了用微波消解ICP-MS测定稻谷中镉含量时,镉的同位素111Cd与114Cd测定结果出现差异的原因:是微波消解时使用了2m L优级纯的过氧化氢,过氧化氢中锡元素的本底含量高,含(300~700)ng/m L,对稻谷中镉的贡献不一;解决111Cd与114Cd测定结果的差异的方法:微波消解时可不使用过氧化氢,只用硝酸进行微波消解处理。     

影响稻谷脂肪酸值测定结果准确性的探讨

本文通过对稻谷脂肪酸值测定过程的仪器设备,试验条件和操作过程等方面分析探讨影响检验误差的各因素,以确保检验结果的准确性。     

存储温度对保鲜纸中亚氯酸钠留着率的影响

目的研究不同存储温度对保鲜纸中亚氯酸钠留着率的影响。方法利用碘量法测定亚氯酸钠的留着率,用白度仪测定基材白度的变化情况,用X射线光电子能谱仪(XPS)对纤维表面的化学特性进行表征。结果不同温度下,亚氯酸钠留着率呈现出不同的下降趋势。通过白度测定结果可知,木素和亚氯酸钠反应会造成亚氯酸钠留着率降低。XPS测试结果表明,存储温度升高,木素和抽出物含量降低。结论低温环境有利于亚氯酸钠留着率的保持。     

稻谷薄层真空脉动干燥特性及含水率预测模型

为探究稻谷的真空脉动干燥特性,提升干燥品质,本文研究了不同干燥温度、相对真空度和真空保持时间对稻谷干燥时间和速率的影响;同时根据单因素试验结果进行正交试验确定稻谷真空脉动干燥最佳工艺参数;构建基于最小二乘支持向量机(LS-SVM)的稻谷干燥过程含水率预测模型。结果表明:干燥温度和真空度对稻谷干燥时间、爆腰增率均有显著影响,各因素影响顺序为干燥温度真空度真空保持时间,此时稻谷的最佳干燥工艺为:干燥温度55℃,真空度80 kPa,真空保持时间3 min,干燥过程中有效水分系数为(1.7371～3.1285)×10~(-10) m~2/s,干燥活化能为35.59 kJ/(mol·K)。利用网格搜索和交叉验证的方法进行参数寻优,建立LS-SVM的含水率预测模型精度高,平均预测精度达99.4425%,为稻谷真空脉动干燥应用及含水率在线预测提供理论依据。     

稻谷真空干燥动力学实验研究

以干基含水率为28.02%的稻谷为研究对象,研究了相对压力(-20、-50和-80 k Pa)和温度(40、50、60和70℃)对稻谷真空干燥特性的影响。结果表明,相对压力对稻谷干燥的影响不大,温度对稻谷干燥的影响较明显。温度越高,达到目标含水率所需的时间越短,干燥速率和峰值干燥速率越大。采用9种不同的等温干燥模型对不同干燥温度下的实验结果进行拟合分析,模型拟合的相关系数R2均高于0.9860,拟合效果均较好,其中Midilli and Kucuk模型的R2均高于0.9990,拟合效果最好。稻谷的有效水分扩散系数随温度的升高而增大,干燥活化能为37.43 k J/mol。     

Φ100mm SHPB应力均匀及恒应变率加载试验技术研究

大直径分离式霍普金森压杆(SHPB)试验装置被越来越多地应用于混凝土等脆性材料的高应变率力学性能研究,试件在破坏前,满足应力均匀分布要求,且保持恒应变率加载,是保证SHPB试验有效性及试验结果可靠性的关键.以提高试验结果准确性为研究目标,以C50素混凝土的SHPB试验为例,采用Φ100mm SHPB试验装置,对试验中的应力均匀及恒应变率加载技术进行研究,包括波形整形器的设计、近似恒应变率的估算、最佳近似恒应变率的确定以及应力均匀性检验.结果表明:厚度为1mm,直径分别为20mm、25mm、30mm、35mm的H62黄铜波形整形器对入射波形有明显的改善效果,可将入射脉冲上升沿的升时延长1～2倍,且波形呈半正弦状;应变率对于波形整形器的直径很敏感,随着整形器直径的增大,最佳近似恒应变率也在增加,一个几何尺寸的波形整形器只能对应于一个最佳近似恒应变率,且与整形器的直径之间满足线性函数关系.     

烟丝整丝率影响因素问题探讨

找出影响烟丝整丝率的关键因素,为提高烟丝整丝率提供参考依据。卷烟实际生产过程中,首先控制烟丝结构中叶丝、梗丝和膨胀烟丝的整丝率,然后适当控制烘丝加工参数,并对切丝含水率进行合理调控,可达到稳定和提高烟丝整丝率的目的。     

Ф100mmSHPB应力均匀及恒应变率加载试验技术研究

大直径分离式霍普金森压杆（SHPB）试验装置被越来越多地应用于混凝土等脆性材料的高应变率力学性能研究,试件在破坏前,满足应力均匀分布要求,且保持恒应变率加载,是保证SHPB试验有效性及试验结果可靠性的关键。以提高试验结果准确性为研究目标,以C50素混凝土的SHPB试验为例,采用Ф100mmSHPB试验装置,对试验中的应力均匀及恒应变率加载技术进行研究,包括波形整形器的设计、近似恒应变率的估算、最佳近似恒应变率的确定以及应力均匀性检验。结果表明：厚度为1mm,直径分别为20mm、25mm、30mm、35mm的H62黄铜波形整形器对入射波形有明显的改善效果,可将入射脉冲上升沿的升时延长1～2倍,且波形呈半正弦状;应变率对于波形整形器的直径很敏感,随着整形器直径的增大,最佳近似恒应变率也在增加,一个几何尺寸的波形整形器只能对应于一个最佳近似恒应变率,且与整形器的直径之间满足线性函数关系。     

Quality Assurance of Rice and Paddy Moisture Measurements in Thailand

A bilateral comparison in moisture measurement between the National Institute of Metrology Thailand (NIMT) and the Central Bureau of Weights and Measures (CBWM) was organized for quality assuring of rice and paddy moisture measurement in Thailand. The bilateral comparison was conducted by using the same batch of sample and moisture meter as transfer device. It consisted of two parts: moisture measurement in rice and in paddy. A rice moisture meter belonging to CBWM and rice standards prepared at the nominal moisture content of 10 %, 12 %, 14 % and 16 % at NIMT, were used for rice moisture comparison, while a paddy moisture meter belonging to NIMT and paddy standards prepared at the nominal moisture content of 12 %, 14 %, 16 % and 18 % at CBWM, were used for paddy moisture comparison. Both laboratories measured the moisture content of a sample by using the standard method in ISO 712 and used that sample to calibrate a moisture meter by means of the method based on ISO 7700-1. Since the moisture content of the sample can change during the comparison, correction values in moisture content between the standard value and the reading value from the moisture meter are used as calibration results for the comparison evaluation. For the rice moisture comparison, differences in the correction value measured by the two laboratories vary from 0.18 % to 0.46 %, with their combined comparison uncertainty of 0.37 % (\(\hbox {k}= 2)\). The main contribution to the difference comes from the standard values from both laboratories differing from 0.27 % to 0.53 %, as the rice standard was found to drift in moisture content less than 0.05 %. Similarly to the rice moisture comparison, differences in the correction value for the paddy moisture measurement range from 0.08 % to 0.56 % with the combined comparison uncertainty of 0.38  % (\(\hbox {k} = 2)\), whereas the stability in moisture content of the paddy sample at NIMT was found to be within 0.12 %.     

Simulation of grain segregation under horizontal rotational oscillations

The segregation of paddy rice and short stalks under horizontal rotational oscillations is investigated through numerical simulation by using a 3D discrete element method. Simulation results show that paddy rice and short stalk particles are divided into two layers under periodic horizontal rotational oscillations and that short stalks finally move to the top layer of paddy rice. The grain segregation mechanism is analyzed in detail on the basis of theory of gap filling, momentum, and kinetic energy. The effects of vibration parameters (frequency and amplitude) on grain segregation are determined by using the volume concentration index of materials. In a certain range of vibration parameters, frequency and amplitude significantly influence early segregation, and the grain segregation effects caused by different parameters are basically the same along with the increase in vibration time.     

Effects of rice straw ash amendment on Cu solubility and distribution in flooded rice paddy soils

Rice straw burning is a common post-harvest practice on rice paddy land, and it leads to the accumulation of rice straw ash (RSA) in paddy soil. To understand the role of RSA in determining the mobility and bioavailability of metal contaminants, this study investigated the effects of RSA amendment on the solubility and distribution of Cu in contaminated rice paddy soils with flooding incubation. The addition of RSA to the soils suppressed the release of Cu into the soil solutions, which was primarily attributed to the metal-binding capacity of the RSA. Additionally, after the soils were flooded, the increase in soil pH and decrease in redox potential resulted in the transformation of Cu into less soluble forms. The RSA amendment appeared to enhance the changes in pH and redox potential of the flooded soils and, consequently, the immobilization of Cu in the soils. The results suggest that the RSA can retard the bioavailability and movement of the metal in contaminated soils and, thus, lower the potential environmental risk of Cu toxicity.     

Suppressive effects of magnesium oxide materials on cadmium uptake and accumulation into rice grains II: Suppression of cadmium uptake and accumulation into rice grains due to application of magnesium oxide materials

The objective of this study is to assess the applicability of a commercial magnesium oxide (MgO) and a composite material containing MgO and natural minerals ('MgO-SH-A') as the soil amendments for suppression of cadmium (Cd) uptake and accumulation into rice grains. A cultivation experiment of rice plants (Oryza sativa L. cv. Kinuhikari) was conducted in an actual Cd-contaminated alluvial paddy field to evaluate the effectiveness of these materials. The 'plant available' fractions of Cd in the paddy soil significantly decreased by application of commercial MgO at 2250 kg ha(-1) or MgO-SH-A at 4500 kg ha(-1). These decreases would be primarily attributed to the increase in soil pH due to applications of the MgO materials because these soil Cd fractions were significantly negatively correlated with the soil pH. Even under a suppressive condition for Cd uptake by rice plants, i.e., continuous flooding of the paddy field around the heading stage, applications of these materials further reduced Cd concentration in brown rice as compared to that from the control. It was concluded that the two MgO materials examined would be effective in preventing Cd contamination of rice grains grown in Cd-polluted paddy fields.     

Flow Properties of Awned and De-Awned Paddy Grains Through a Horizontal Hopper Orifice

In a modern rice mill, de-awning is an important process before husking operation to eliminate awns of the paddy grains for easy conveying in the elevators, chutes, and hopper orifices. This experiment was conducted to study the effects of independent variables of de-awning percentage, orifice cross-sectional area and paddy grains moisture content on the flowing rate (FR) and variations of flowing rate (VFR) of paddy grains through a horizontal hopper orifice. A local paddy variety, namely, Hashemi, which is characterized by long awns was used as a raw material in the test. The results indicated that flow rate (FR) and variations on flow rate (VFR) significantly (p < 0.01) affected by the de-awning percentage, orifice cross-sectional area and paddy moisture content. FR increased from 45.00 to 87.57 g s^?1 and VFR decreased from 54.93 to 21.49%, as de-awning increased from 14.67 to 84.93%. FR increased as the orifice cross-sectional area increased from 12.08 to 34.81 cm²; however, higher VFR was obtained at lower orifice cross-sectional area. For the awned (87% of the grains had originally awns) and de-awned paddy (82% of the grains were de-awned), FR decreased as the paddy moisture content increased from 8.67 to 15.06%wb; while VFR increased at higher grain moisture content.     

Present and future studies on environmental radioactivity in Japan

In this paper, recent studies on environmental radioactivity are briefly reviewed. Considering the growing dependency on nuclear energy in Asia, emphasis has been given to (14)C cycle at the ground surface including rice paddy fields and to long-range atmospheric transport of natural and anthropogenic radioactive materials. Studies on the dynamic behaviour of (14)C are being carried out and some important experimental results are becoming available for models of (14)C migration in rice paddy. Long-range atmospheric transport models have been improved substantially by using sophisticated physical models and simulation techniques to improve emergency preparedness. Although our knowledge on radon flux distribution in Asia has been improved and radon has become a more reliable atmospheric tracer, we still need more intensive measurements of exhalation flux and atmospheric concentration of radon and radium content in soil.     

Correction to: Sustainable bioethanol and value‑added chemicals production from paddy residues at pilot scale

Clean Technologies and Environmental Policy - Biorefineries from paddy residues (rice straw and rice husk) have a high potential to satisfy human society’s need for sustainable fuel and...     

弱织构热轧钢板氧化皮的定量相分析

首先对具有弱织构热轧钢板表面的氧化皮进行了X射线衍射（XRD）分析,然后选用Highscoreplus软件通过Rietveld全谱拟合方法对得到的XRD谱进行精修,实现了对氧化皮的定量相分析,最后对精修结果进行了择优取向校正,并研究了择优取向校正对拟合结果的影响。结果表明：经过择优取向校正的Rietveld全谱拟合判据均小于未经过择优取向校正的,而经过择优取向校正后的精修结果比未经过择优取向校正的精修结果更准确;Rietveld全谱拟合的结果均为收敛,拟合的判别因子Rp,Rvp和X均较小。     

Strength development of concrete with rice-husk ash

This paper presents a study on the development of compressive strength up to 91 days of concretes with rice-husk ash (RHA), in which residual RHA from a rice paddy milling industry in Uruguay and RHA produced by controlled incineration from the USA were used for comparison. Two different replacement percentages of cement by RHA, 10% and 20%, and three different water/cementicious material ratios (0.50, 0.40 and 0.32), were used. The results are compared with those of the concrete without RHA, with splitting tensile strength and air permeability. It is concluded that residual RHA provides a positive effect on the compressive strength at early ages, but the long term behavior of the concretes with RHA produced by controlled incineration was more significant. Results of splitting tensile and air permeability reveal the significance of the filler and pozzolanic effect for the concretes with residual RHA and RHA produced by controlled incineration.     

Biosorption of methylene blue from aqueous solution by rice husk in a fixed-bed column

In this study, the ability of rice husk to adsorb methylene blue (MB) from aqueous solution was investigated in a fixed-bed column. The effects of important parameters, such as the value of initial pH, existed salt, the flow rate, the influent concentration of MB and bed depth, were studied. The Thomas model was applied to adsorption of MB at different flow rate, influent concentration and bed depth to predict the breakthrough curves and to determine the characteristic parameters of the column useful for process design using non-linear regression. The bed-depth/service time analysis (BDST) model was also applied at different bed depth to predict the breakthrough curves. The two models were found suitable for describing the biosorption process of the dynamic behavior of the rice husk column. All the results suggested that rice husk as adsorbent to removal MB from solution be efficient, and the rate of biosorption process be rapid. When the flow rate was 8.2ml min(-1) and the influent concentration of MB was 50mgl(-1), the equilibrium adsorption biomass reached 4.41mgg(-1) according to Thomas model.