大气对近地面无线激光通信链路的影响

由于无线光通信有通信容量大,保密性好,抗电磁干扰,结构简单等优点,近年来随着适合无线光通信应用的先进通信电子设备等技术的成熟,又掀起了对其研究的热潮,无线光通信被视为下一代光通信的发展方向之一。首先指出了无线光通信的技术优势并回顾了其发展史,阐述了大气对近地面无线激光通信系统链路的影响,重点研究了大气的衰减和大气湍流效应中的光强(大气)闪烁、光束弯曲和漂移及光束展宽,并对大气闪烁进行了仿真。最后对近地面无线光通信进行了展望。     

Clarification of apple juice by electroflotation

Apple Juice industry is in search of a simplified technology which enables a quick clarification and stabilisation of apple juice. This study aimed to evaluate the potential of electroflotation as an alternative for the clarification of apple juice. Clarification of apple juice by electroflotation was first done at various current densities (10, 20 and 40 mA/cm²) with and without addition of gelatin (200 mg/l). Afterwards, the electroflotation treatments were done at a current density of 20 mA/cm² with various concentrations of added gelatin (0, 50, 100 and 200 mg/l). It was shown that electroflotation treatments alone was efficient to reduce the tannin and protein contents of apple juice. However, the decrease in the protein content was in large part due to the use of pectinases prior to the electroflotation treatments. The use of gelatin in combination with the electroflotation aided in the clarification process. The highest gelatin concentration used in this study (200 mg/l) resulted in a better reduction of tannin and protein levels, while a current density of 20 mA/cm² was found to be optimal. Turbidity observed in the juices clarified with electroflotation treatments was in average lower than 10 NTU but higher than 2 NTU which is generally required to produce a stable clarified juice. Brix degree and pH of the apple juice was not affected by the electroflotation treatments while the color was improved.

Industrial relevance

The production of clarified and stable apple juice is a subject of interest for the beverages industries. The clarification step which remained long and discontinuous implied the addition of a large quantity of pectolytic enzyme and of clarifying agents (such as gelatin) to the freshly pressed juice to induce the precipitation of proteins and other suspended matter in 15–20 h. Fining treatments were followed by a separation step usually consisting of decantation and classical filtration on filter-press, or flotation by dispersed gas. The development of membrane separation processes to replace the traditional approach has enabled the automation of the whole production resulting in lower labor requirement and a considerably shorter process time than the traditional process.However, the performance of membrane separation processes is influenced by the declining permeate flux with time, which is due to membrane fouling. In some instances, permeate flux decline makes membrane separation processes unattractive for the clarification of apple juice. To our knowledge, we are the first research group to use electroflotation (EF) for clarification of apple juice. It was shown that EF treatments alone were efficient to reduce the tannin and protein contents of apple juice. In addition, the use of gelatin in combination with the EF aided in the clarification process. Turbidity observed in the juices clarified with EF treatments for 30 min was in average lower than 10 NTU. Brix degree and pH of the apple juice were not affected by the EF treatments while the color was improved.When compared to the values reported in the literature for flotation by dispersed gas, it seems that EF shows better efficiency than flotation in decreasing the juice turbidity (99% decrease for EF as compared to 90% decrease for flotation). In addition, for experiments carried out by conventional flotation larger amount of fining agent are used (70–150 mg of gelatin/l, 400–800 mg/l of silica sol and 200–500 mg/l of bentonite). For these reasons, the new process we propose is advantageous when compared to the traditional flotation approach and it should have a measurable impact on the advancements in the production of clarified apple juice. If used as a pre-treatment to ultrafiltration clarification, it is expected that it would reduce membrane fouling resulting in higher productivity.     

Silica particles settling characteristics and removal performances of oxide chemical mechanical polishing wastewater treated by electrocoagulation technology

The purpose of this study was to explore the feasibility of removing silica particles and reducing turbidity from oxide chemical mechanical polishing (oxide-CMP) wastewater. Based on the dynamic characteristics of batch electrocoagulation, three operating stages (lag, reactive, and stabilizing) are proposed to identify the relationships among the zeta potential of the silica particles, solution turbidity, and the corresponding mean particle size of the silica. Experimental results show that the silica particles were destabilized and settled at the critical mean particle size, which was estimated to be above 520 nm after 10 min, and the corresponding turbidity removal mostly occurred during the reactive stage. Furthermore, the corresponding mean particle size varied from 520 to 1900 nm as the treatment time progressed from 10 to 20 min, which also occurred during the reactive stage. Several parameters, including different electrode pairs, electrolyte concentration, applied voltage, and the optimum condition of power input were investigated. Experimental results indicate that a Fe/Al electrode pair is the most efficient choice of the four electrode pair combinations in terms of energy consumption. The optimum electrolyte concentration and applied voltage were found to be 200 ppm NaCl and 30 V, respectively.     

Advantages of Preozonation in the Upgrading of the Mont Valérien Plant in France

The Mont Valérien plant supplies water to the western suburbs of Paris. Raw water comes from the River Seine downstream from the city. The old plant comprised two treatment lines: a slow sand filtration line built 80 years ago and a rapid settling and filtration line built in 1960. The process for the upgraded plant was determined after an in-depth study including industrial-scale experiments and laboratory tests.

The new treatment line includes the following: preozonation, oagulationflocculation and settling in a sludge-blanket type settling tank (PULSATOR), rapid gravity sand filtration, ozonation, and granular activated carbon filtration.

Results from laboratory tests used for the design are presented: ozonation rate, advantages for the quality of the treated water, expected reagejit savings, etc.     

Prediction of grape polyphenol astringency by means of a fluorimetric micro-plate assay

Previous works have demonstrated that astringency can be predicted on the basis of turbidity developed by polyphenol/mucin mixes. In the present study, a micro-plate assay, based on the ability of haze particles to screen the radiation emitted by a fluorescent compound (I%), is proposed for polyphenol/mucin reactivity estimation. Grape seed extract (GSE) solutions prepared in a range of physiochemical active concentrations (0.0–2.9 g/L) were reacted with mucin. A significant linear relationship (r = 0.99; p = 0.000) was found between turbidity (NTU) and I% values of GSE/mucin samples. Within the experimental range of phenolic samples, the CV value of I% determinations was always lower than 10%. The relationship between sensory and instrumental responses, as a function of phenolic solution characteristics, was investigated. Variations in phenol concentration and pH induce similar modifications of both the intensity of perceived astringency and I% values. A significant linear relationship (r = 0.98; p = 0.000) was found by relating sensory ratings to the relevant I% values.     

APMS-10G浑浊度传感器在模糊控制工业洗衣机中的应用

研究了APMS-10G浑浊度传感器的工作原理、特点及通信协议，设计了基于APMS-10G浑浊度数据采集系统。给出了详细的浑浊度数据采集电路，完成了浑浊度数据采集的软件设计，并成功应用于工业洗衣机模糊控制系统。基于APMS-10G浑浊度传感器的模糊控制工业洗衣机取得了良好的节水、节电、省时效果，提高了洗涤效率。     

Study of Formulation and Stability of Co-surfactant Free Water-in-Olive Oil Nano- and Submicron Emulsions with Food Grade Non-ionic Surfactants

Nanoemulsions are of great interest in food industry finding various food applications. However, oil-in-water (o/w) nanoemulsions have been intensively investigated, but there are few studies on w/o nanoemulsions. In the present work the preparation of nanoemulsions with olive oil using non-ionic surfactants (Tween 20, 40, 60, 80, Span 20, 80) without the addition of a co-surfactant was studied and their emulsion properties and stability were examined. The stable nanoemulsions were presented in ternary phase diagrams (oil–water-surfactant) for each surfactant and the emulsifying ability of the efficient surfactants was determined. The nanoemulsions properties were evaluated in relationship to compositional components. From the results of this study it can be concluded that stable olive oil nanoemulsions without use of a co-surfactant were obtained and moreover the most efficient type of emulsifier and its ratio of addition in the system were determined.