用于敞开式变电站的特高压开关设备

作为1 100 kV的UHV(特高压)输电,面临技术--生态环境的巨大挑战.变电站的UHV开关装置模块,需要的是可靠、成本/效益比好、环境友好、可维护的方案.对于这些所需的参数以及技术规范的验证,采用AIS(空气隔离变电所)技术能完全满足这些需要.介绍由瓷柱式断路器、隔离开关和NCIT(非传统互感器)所组成的UHV模块.这些装置是根据模块原理预先设计好的,其中的设备间的连接肯定允许快速安装.在变电站设备控制和检测方面,模块是预制标准化.加拿大和德国的试验站对断路器、隔离开关等独立的开关元件,在1 100 kV上做BIL、SIL和工频等绝缘试验,性能表现非常优越.因为对于特高压电压等级,IEC标准至今尚未规定,所以将根据外推法和现场数据作合理解释.瓷柱式断路器采用了最新复合绝缘体技术,在安全方面有所改进.AIS方案其他的关键技术,例如环境保护和成本,在可比的功能间,根据市场估计价值,与GIS解决方法作了比较.     

Simple single longitudinal mode Q-switched Nd:YAG oscillator

A simple three-mirror resonator is considered for longitudinal mode control in a passivelyQ-switched Nd:YAG laser. This configuration provides temporally smooth output pulses with duration determined by dye concentration and continuously variable from 300 to 10 ns. Previous problems with spatial beam quality can be minimized by careful arrangement of cavity components.     

Secondary production and biomass of Cladocera in marginal lakes after the recovery of their hydrologic connectivity in a river–reservoir transition zone

Secondary production and biomass of Cladoceran populations were studied in two marginal lakes whose connections to a tropical river were re‐established after a prolonged drought period. This study investigates the process of the recovery of the cladoceran populations after the hydrologic reconnection with the river was established. It also compares the energetic dynamic of Cladoceran populations in two lakes, one with a wide and another with a narrow connection to the river. Samples were collected every 48 h for 1 month, immediately after the river water inflow to the lakes, and 7 months after the reconnection with the river during a period of hydrologic stability of the lakes. Secondary production and biomass were compared between lakes and periods, to identify the main controlling factors for the observed variations in Cladoceran productivity. Cladocerans were more productive during the rainy period, immediately after the increased water volume, when high water temperatures were recorded in the two lacustrine systems. Secondary production and biomass values were higher in the more eutrophic lake, wherein the water chemical and physical characteristics presented slow alterations during the rainy period. Although the lake with large spatial heterogeneity and linkages with the river exhibited high Cladoceran richness, the secondary production and biomass were low. Variations in water volumes and temperatures and changes in trophic status affected the secondary production and biomass of the main Cladoceran species in the two studied lakes.     

Comparison of glycemic index of spelt and wheat bread in human volunteers

The assessment of the glycemic index (GI) seems to be an important parameter to take into account in order to better understand the physiologic effects of foods with high carbohydrate levels. Among cereals, which are major sources of carbohydrates, spelt (Triticum spelta L.) has been considered as particularly interesting from a nutritional point of view. The aim of this study was to evaluate in vivo the GI of white spelt bread in healthy subjects. The wheat (Triticum aestivum L.) white bread was used as reference food. To avoid differences in the production of both breads, spelt and wheat breads were baked under the same controlled conditions. Results showed that the glycemic profile of spelt white bread was not different from that of wheat white bread (GI of 93 ± 9). The area under the glycemic curve significantly and negatively correlated to fasting glycemia and carbohydrate intake during evening meals preceding the test. In conclusion, the glycemic response to spelt bread was similar to that of wheat bread. However, in order to avoid more inter-individual variability, our data supports the importance to propose standardised carbohydrate content for the last meal before evaluating the GI of food.     

La housse isolée, un outil logistique particulier pour les denrées thermosensiblesThe insulating cover, a particular logistic means for thermo-sensitive foodstuffs

Thermal protection efficiency of different insulating paletts-covers were tested in a particular logistic process, such as interfaces between refrigerated transport/platform/delivery where the temperature (ambiante) was uncontrolled. The overall coefficient of heat transfert (K) of these covers was measured. The experiments were carried out with individual pallets placed in a test room with a control temperature, and in a tot liner trailer placed in a test tunnel controlled at +25°C.This paper emphasizes the advantages and the disadvantages of use in an extensive sense (thermal protection, mecanical resistance, logistics conditions, …).