The effect of postharvest calcium application on tissue calcium concentration, quality attributes, incidence of flesh browning and cell wall physicochemical aspects of peach fruits

The effects of postharvest calcium applications on cell wall properties and quality attributes of peach fruits (Prunus persica L. Batsch, cv. ‘Andross’) after harvest or cold storage up to 4 weeks were determined. The fruits were immersed in deionised water or in different calcium sources (calcium chloride, calcium lactate and calcium propionate) at two calcium concentrations (62.5 and 187.5 mM Ca). Calcium concentration profiles in fruits (peel and flesh), in cell wall and in pectin fractions were determined. The calcium content in the peel increased up to 2.7-fold, whereas flesh calcium increased up to 74%, 1 day after immersion. The increase of flesh calcium was accompanied by increase of cell wall calcium, which corresponded to a significant increase of calcium in the water-insoluble pectin fraction. However, calcium became saturated in the water-insoluble, but not water-soluble, pectin fraction with 62.5 mM Ca treatment. Treatment with 62.5 mM Ca salts was as effective as higher concentrations of calcium chloride maintaining tissue firmness during storage. Inversely, calcium lactate and calcium propionate at high concentrations (187.5 mM Ca) caused toxicity symptoms on the fruit surface, expressed as skin discoloration and superficial pitting, leading to additional chemical changes and reduced tissue firmness. Postharvest calcium applications limited the intense of chilling injury symptoms, expressed as flesh browning after 4 weeks cold storage. Peach fruits with severe flesh browning symptoms were characterized by reduced ethylene production, and reduced activities of the pectin modifying enzymes poly-galacturonase and pectin-methyl-esterase.     

供配电系统电压暂降的防治

阐述了电压暂降的成因和危害,提出从两个方面防治电压暂降。着重介绍了供配电系统机械储能装置、动态电压调节器、静态电容器、静态补偿器等电压自动补偿措施,可为相关电气设计人员提供参考。     

户外GIS气室外用紧固件的选用

针对户外气体绝缘金属封闭开关设备气室外用紧固件的生锈问题,分析了现阶段碳钢紧固件常用的三种表面防锈防腐处理措施热浸镀锌和达克罗特性及不锈钢材质紧固件的特性,讨论了紧固件设计安装时应注意的事项,并比较了这三类紧固件的防锈防腐特性,综合考虑成本等因素后,给出了户外气体绝缘金属封闭开关设备气室外用紧固件比较经济合理的选用方案。     

Identification of the Critical Characteristics of Different Types of Voltage Sags for Synchronous Machine Torque Oscillations

Abstract—This article investigates the effects of symmetrical and unsymmetrical voltage sags on an important characteristic of torque pulsation of synchronous machines. Voltage sags may cause high torque pulsations, which can damage the shaft or equipment connected to it. Duration, magnitude,and initial point-on-wave of the voltage sag are the major characteristics that can influence the synchronous motors torque transients. The effect of the characteristics on the severity of the transient torque is clarified parametrically, and the critical characteristics of each type of voltage sag are extracted. A theoretical analysis is first presented to determine the severest conditions. In this analysis, for each type of voltage sag, the stator flux trajectory in complex coordination is traced to monitor its variation during and after sag. By this method, the effects of different sag types can easily be compared during the sag and at the sag ending instant. To justify the theoretical analysis, simulations of a typical synchronous motor are carried out that confirm the theoretical analysis.     

ASTM-D885-98聚酯帘线上胶量测试方法的改进

新方法提出了用水浴加热法对帘线进行对流溶解,以改善溶样温度的均匀性,并在抽滤过程中控制抽吸真空度等措施,改进后的方法测试相对误差已小于1%。     

层状岩体台阶爆破数值模拟研究与工程应用

对层状岩体爆破中岩层倾向与台阶坡面角度之间的关系进行了分析,且利用有限元分析软件ANSYSLS-DY-NA2D,对岩层倾向与台阶坡面角度的不同空间位置关系情况下的爆破进行了数值模拟,发现当岩层倾向与台阶坡面垂直时为爆堆推进方向的爆破效果最优。进行了现场工程对比试验,证明当岩层倾向与台阶坡面垂直时,大块率最小,仅为2.14%,爆破整体效果良好。     

Plasmonic Fano resonance and dip of Au-SiO2-Au nanomatryoshka

This study theoretically investigates Fano resonances and dips of an Au-SiO₂-Au nanomatryoshka that is excited by a nearby electric dipole. An analytical solution of dyadic Green''s functions is used to analyze the radiative and nonradiative power spectra of a radial dipole in the proximity of a nanomatryoshka. From these spectra, the plasmon modes and Fano resonances that accompany the Fano dips are identified. In addition, the scattering and absorption spectra of a nanomatryoshka that is illuminated by a plane wave are investigated to confirm these modes and Fano dips. Our results reveal that a Fano dip splits each of the dipole and quadrupole modes into bonding and anti-bonding modes. The Fano dip and resonance result from the destructive interference of the plasmon modes of the Au shell and the Au core. The Fano factors that are obtained from the nonradiative power spectra of the Au shell and the Au core of a nanomatryoshka are in accordance with those obtained from the absorption cross section spectra. Moreover, these Fano factors increase as the plasmonic coupling of the Au shell with the core increases for both dipole and quadrupole modes.     

Measuring the process efficiency of controlled gas metal arc welding processes

Abstract

The thermal or process efficiency in gas metal arc welding (GMAW) is a crucial input to numerical models of the process and requires the use of an accurate welding calorimeter. In this paper, the authors compare a liquid nitrogen calorimeter with an insulated box calorimeter for measuring the process efficiency of Fronius cold metal transfer, Lincoln surface tension transfer and RapidArc, Kemppi FastRoot and standard pulsed GMAW. All of the controlled dip transfer processes had a process efficiency of ～85% when measured with the liquid nitrogen calorimeter. This value was slightly higher when welding in a groove and slightly lower for the RapidArc and pulsed GMAW. The efficiency measured with the insulated box calorimeter was slightly lower, but it had the advantage of a much smaller random error.     

测井新技术在桩西地区生产井中的应用

利用成像测井、核磁共振测井、地层倾角测井、多极子阵列声波测井等先进的测井装备对桩西油田的生产井实施测井,得到的有效孔隙度与岩电分析结果和地区经验数据具有很好的一致性,提高了地层流体的评价精度;确定了地层产状及古流水方向;经处理后的阵列声波测井资料提供了准确的纵波时差、横波时差和斯通利波时差,进而可以得到所需的岩石物理参数;声成像资料提供的储层裂缝发育情况揭示了井段内发育的裂缝类型、裂缝开启程度及对地层应力的分析依据.这些测井信息的获取弥补了常规测井资料的不足,为今后油田的地质分析和勘探开发提供了丰富的资料.