实现信息高速公路的途径

本文提出了在人类进入信息时代的过程中，最先实现信息化的国家就可以获得飞速发展的机会的观点，并着重指出，实现信息高速公路的唯一途径是实行鼓励竞争和电信业全面开放的政策。     

连铸用新型钢包更换设备

1.前言 日本钢铁公司设备部研制成功一种新型的钢包更换设备,这种设备已安装在现场,如电炉车间。 这一设备意图利用现有的钢包吊车,并获得在地面上有一安全通道。 2.新型钢包更换方法 这种新型的钢包更换设备包括:钢包吊车、钢包升降机和钢包回转台(如图1所示),更换钢包     

The influence of different centralised pre-packaging systems on the shelf-life of fresh pork

The influence of different centralised pre-packaging systems (PVC, modified atmosphere packaging (MAP), 25% CO(2) and 75% O(2), vacuum skin packaging (VSP) and the mother bag concept, 100% CO(2)) on the shelf-life (0, 7, 14 and 21 days at 0°C) of fresh pork was determined using microbiological, colour, odour and acceptability characteristics. All the packaging treatments were equally efficient for the first 4 days of retail display. In the extended shelf-life study (7, 14 and 21 days) the mother bag centralised packaging system gave the most promising shelf-life results (21 days) and was also judged superior in terms of odour. Modified atmosphere packaging (14 days) and VSP (7 days) may be considered as other possible options.     

Annihilation density distribution calculations for medically important positron emitters

The effect of positron range on the image-plane resolution of tomographic images is evaluated through calculations based on a model which employs beta-decay energy spectra and an empirical range formula. Predicted range distribution functions are compared with published measurements for three medically important positron emitters: (11 )C, (68)Ga, and (82)Rb. The effect of tomographic slice thickness on point-source annihilation distribution functions is also demonstrated. Line-spread functions are calculated using the model, for the above isotopes as well as for (18)F, (15)O, and (13)N. Image-plane resolution predictions are made for high-resolution positron cameras for various positron emitting isotopes with end-point energies up to 4 MeV.     

Hydraulic behaviour and removal efficiencies of two H-SSF constructed wetlands for wastewater reuse with different operational life

This work focuses on the performance evaluation of two full-scale horizontal suburface flow constructed wetlands (H-SSF CWs) working in parallel, which have an almost equal surface area (about 2,000 m2) but with different operational lives: 8 and 3 years. Both H-SSF CWs, located in Southern Italy (Sicily), are used for tertiary treatment of the effluent of a conventional wastewater treatment plant. This study evaluates and compares H-SSF CW efficiency both in terms of water quality improvement (removal percentage) and achievement of Italian wastewater discharge and irrigation reuse limits. The mean removal percentage, for the overall operational life, of TSS, COD and BOD (80%, 63%, 58% obtained for H-SSF1 and 67%, 38%, 41% for H-SSF2), confirm the high reliability of CWs for wastewater treatment. However, despite the satisfactory removal of microbial indicators (the mean E. coli removal was up to 2.5 log unit for both beds), CWs didn't achieve the Italian limits for wastewater reuse. Information on hydraulic properties of the CWs were extracted from breakthrough curves of a non-reactive tracer (NaCl). By comparing the nominal (tau(n)) and actual residence time (tau), hydraulic behaviour was revealed.     

The use of CFD modelling to optimise measurement of overflow rates in a downstream-controlled dual-overflow structure

The measurement of the flow through complex combined sewer overflow structures in the frame of automated monitoring remains difficult. In this paper, a methodology based on the use of computational fluid dynamics (CFD) modelling in order to improve the instrumentation of a downstream-controlled dual-overflow structure is presented. The dual-overflow structure is composed of two combined sewer overflows (CSOs) connected by a rectangular channel and controlled by a downstream gate located at the entry of the Meyzieu waste water treatment plant (close to Lyon, France). The analysis of the CFD results provides: (i) a better understanding of the interaction between the two CSOs--that means the hydraulic operation, the hydrodynamic behaviour, the backflow effect--and (ii) an ability to optimise the location of the water depth sensor. The measured water depth is used to assess the overflow rate by means of a numerical relationship. Uncertainties are also assessed.     

Invited article: development of high-field superconducting Ioffe magnetic traps

We describe the design, construction, and performance of three generations of superconducting Ioffe magnetic traps. The first two are low current traps, built from four racetrack shaped quadrupole coils and two solenoid assemblies. Coils are wet wound with multifilament NbTi superconducting wires embedded in epoxy matrices. The magnet bore diameters are 51 and 105 mm with identical trap depths of 1.0 T at their operating currents and at 4.2 K. A third trap uses a high current accelerator-type quadrupole magnet and two low current solenoids. This trap has a bore diameter of 140 mm and tested trap depth of 2.8 T. Both low current traps show signs of excessive training. The high current hybrid trap, on the other hand, exhibits good training behavior and is amenable to quench protection.