High-performance lift augmentation dynamic seals for turbine bearing compartments

Conventional bearing shaft seal systems used in gas turbine engines are often limited to a sliding velocity of about 100 m/s, differential pressure of 3 bar, gas temperature of 300°C and a seal life less than 8000 h. Advanced engines will require bearing shaft seal systems to operate up to sliding velocity of 200 m/s, differential pressure of 6 bar, gas temperature of 500°C and seal life in excess of 30?000 hours. For seals operating in these advanced conditions, a design with no rubbing contact will be required to achieve long life and reliability. A good validated approach is the use of a gas lift augmentation seal. The design objective for a seal of this type is to have the faces of the seal seek an equilibrium position to avoid any contact. The gap must be small enough to ensure a minimal air leakage, but it must be large enough to limit power dissipation, due to shear in the gas film, and face deformation by shaft displacement, misalignment and vibration. Dynamic seals for a bearing compartment have the following main functions: provide static and dynamic sealing in order to prevent oil leakage from the bearing oil compartment to the air compartment and consequently no oil smell pollution by the use of bleed air; control air leakage to the bearing oil compartment in order to improve performance of the engine and to reduce oil consumption; reduce volume of the oil tank and lubrication system and hence provide weight reduction; to operate in extreme conditions of temperature and with normal and reverse pressure; and reduce the mean time between overhaul (MTBO) and have a very long life. Techspace Aero and Burgmann have carried out design, development and testing of lift augmentation carbon seals and demonstrated that high life and performance levels of these seals are possible in a gas turbine engine environment.     

Improving Parallel Corpus Quality for Chinese-Vietnamese Statistical Machine Translation

The performance of a machine translation system heavily depends on the quantity and quality of the bilingual language resource.However,getting a parallel corpus,which has a large scale and is of high quality,is a very difficult task especially for low resource languages such as Chinese-Vietnamese.Fortunately,multilingual user generated contents (UGC),such as bilingual movie subtitles,provide us access to automatic construction of the parallel corpus.Although the amount of UGC parallel corpora can be considerable,the original corpus is not suitable for statistical machine translation (SMT) systems.The corpus may contain translation errors,sentence mismatching,free translations,etc.To improve the quality of the bilingual corpus for SMT systems,three filtering methods are proposed:sentence length difference,the semantic of sentence pairs,and machine learning.Experiments are conducted on the Chinese to Vietnamese translation corpus.Experimental results demonstrate that all the three methods effectively improve the corpus quality,and the machine translation performance (BLEU score) can be improved by 1.32.     

Improving Parallel Corpus Quality for Chinese-Vietnamese Statistical Machine Translation

The performance of a machine translation system heavily depends on the quantity and quality of the bilingual language resource.However,getting a parallel corpus,which has a large scale and is of high quality,is a very difficult task especially for low resource languages such as ChineseVietnamese.Fortunately,multilingual user generated contents (UGC),such as bilingual movie subtitles,provide us access to automatic construction of the parallel corpus.Although the amount of UGC parallel corpora can be considerable,the original corpus is not suitable for statistical machine translation (SMT) systems.The corpus may contain translation errors,sentence mismatching,free translations,etc.To improve the quality of the bilingual corpus for SMT systems,three filtering methods are proposed:sentence length difference,the semantic of sentence pairs,and machine learning.Experiments are conducted on the Chinese to Vietnamese translation corpus.Experimental results demonstrate that all the three methods effectively improve the corpus quality,and the machine translation performance (BLEU score) can be improved by 1.32.     

An overview of recommender systems in the healthy food domain

Recently, food recommender systems have received increasing attention due to their relevance for healthy living. Most existing studies on the food domain focus on recommendations that suggest proper food items for individual users on the basis of considering their preferences or health problems. These systems also provide functionalities to keep track of nutritional consumption as well as to persuade users to change their eating behavior in positive ways. Also, group recommendation functionalities are very useful in the food domain, especially when a group of users wants to have a dinner together at home or have a birthday party in a restaurant. Such scenarios create many challenges for food recommender systems since the preferences of all group members have to be taken into account in an adequate fashion. In this paper, we present an overview of recommendation techniques for individuals and groups in the healthy food domain. In addition, we analyze the existing state-of-the-art in food recommender systems and discuss research challenges related to the development of future food recommendation technologies.     

Kinetics of ultrasonic extraction of polyphenols,anthocyanins and tannins from five different New Zealand grape pomaces

Polyphenols were extracted from five kinds of New Zealand grape pomace (Sauvignon Blanc, Pinot Gris, Gerwurztraminer, Merlot and Pinot Noir) at 30, 50 and 70 °C in an ultrasonic generator. The extraction kinetics for total phenol, anthocyanin and tannin were determined. The results of dynamics study showed that the extraction of total polyphenols, anthocyanin and tannin followed first-order reaction kinetics during the extraction at 30, 50 and 70 °C. The total phenolic content, anthocyanin conten, and tannin content of water–ethanol extracts from grape pomaces were compared, and the parameters in the extraction kinetics equations were determined. The extraction results showed that the Pinot Noir pomace extract had the highest total phenolic content of 59.95 mg GAE g⁻¹ pomace and tannin content of 79.93 mg EE g⁻¹ pomace. The anthocyanin content in Merlot pomace extract was the highest, which was 4.50 CE g⁻¹ pomace. The results might be of great significance for the development of grape pomace or its polyphenol and/or anthocyanin components as an antioxidant source with natural and inexpensive benefits.     

Carbazole based hole transporting materials for solid state dye sensitizer solar cells: role of the methoxy groups

The synthesis of new organic hole transporting materials (HTMs) based on 3,6‐disubstituted 9H‐carbazole‐3,6‐diamine,N,N,N′,N′‐tetraphenyl‐9‐(4‐methoxyphenyl) derivatives and their applications in solid state dye sensitizer solar cells (DSSCs) are described. The effect of the methoxy group localized on the para position of the diphenylamine moieties on the thermal, electronic and electrochemical properties and photovoltaic performance is discussed. In solid state DSSCs, utilization of the aforementioned HTMs in combination with the dye D102 (TiO₂/D102/HTM/Au) shows a positive influence of the methoxy group on the photovoltaic conversion efficiency compared with unsubstituted diphenylamine grafted groups. A study on the concentration of the HTM is also carried out and shows an optimal concentration around 200 mg mL^?1. Without further optimization, the best device gives a power conversion efficiency of 1.75% under AM 1.5 solar irradiation (100 mW cm^?2).     

Modelling the effects of past and future climate on the risk of bluetongue emergence in Europe

Vector-borne diseases are among those most sensitive to climate because the ecology of vectors and the development rate of pathogens within them are highly dependent on environmental conditions. Bluetongue (BT), a recently emerged arboviral disease of ruminants in Europe, is often cited as an illustration of climate''s impact on disease emergence, although no study has yet tested this association. Here, we develop a framework to quantitatively evaluate the effects of climate on BT''s emergence in Europe by integrating high-resolution climate observations and model simulations within a mechanistic model of BT transmission risk. We demonstrate that a climate-driven model explains, in both space and time, many aspects of BT''s recent emergence and spread, including the 2006 BT outbreak in northwest Europe which occurred in the year of highest projected risk since at least 1960. Furthermore, the model provides mechanistic insight into BT''s emergence, suggesting that the drivers of emergence across Europe differ between the South and the North. Driven by simulated future climate from an ensemble of 11 regional climate models, the model projects increase in the future risk of BT emergence across most of Europe with uncertainty in rate but not in trend. The framework described here is adaptable and applicable to other diseases, where the link between climate and disease transmission risk can be quantified, permitting the evaluation of scale and uncertainty in climate change''s impact on the future of such diseases.     

Mechanical properties of continuous bamboo fiber-reinforced biobased polyamide 11 composites

This study is devoted to the analysis of the properties of continuous bamboo fiber (BF)-reinforced polyamide 11 (PA 11) composites. The SEM observations highlighted continuity between BFs and the polymeric matrix showing a high density of hydrogen bonds. The comparative calorimetric study of the matrix and its composites showed that the crystallinity of PA 11 was not modified by the presence of bamboo fibers. The physical aging observed in PA 11 is no more observed in composites due to physical interactions between PA 11 and BFs. The mechanical properties were investigated by tensile strength and dynamic mechanical analysis. The introduction of BFs enhanced Young's modulus of the matrix by a factor of 10. The presence of BFs also improved the storage shear modulus G′ over the whole temperature range. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47623.