Determining the specific gravities of coarse aggregates utilizing vacuum saturation approach

The current method of specific gravity and absorption of coarse aggregate testing is based on the AASHTO T 85 and ASTM C-127 standards. This approach involves the soaking of the coarse aggregate samples for 15h (AASHTO T 85) and 24 ± 4 h (ASTM C-127), and drying the aggregate to its saturated-surface dry (SSD) state with the aid of a dry absorbent cloth. The attainment of the SSD condition of the coarse aggregate is very subjective, and the total test duration makes it inconvenient for use in construction quality control and quality assurance testing (QC/QA).The objective of this paper is to determine the specific gravity and absorption of coarse aggregates using a new proposed approach utilizing vacuum saturation. In lieu of the conventional soaking period of 24 ± 4 h, this proposed research approach employs the use of 10, 20 and 30 min of vacuum saturation at 30 mm Hg (4.0 kPa) pressure. In this paper, the soaking time is 24 ± 4 h for all the AASHTO method. It is also believed that the 24 ± 4 h shall give better soaking and therefore more accurate test results would be achieved. Vacuum saturating the coarse aggregates aims at removing all the entrapped air within the sample mass, in addition to forcing water into the effective pores of the coarse aggregates. This method is applied to a wide range of coarse aggregates including trap rock, limestone, gravel, steel slag, crushed concrete, and the results are compared statistically with those of AASHTO T 85. Results from the experiments indicate that the vacuum saturation method can replace the AASHTO T 85 for coarse aggregate specific gravity testing at 10, 20 or 30 min of vacuum saturation. A significant finding was that the AASHTO T 85 underestimates the full absorption potential of highly absorptive aggregates when compared to this proposed vacuum saturation approach.     

All-solution-processed blue small molecular organic light-emitting diodes with multilayer device structure

All-solution-processed multilayer blue small molecular organic light-emitting diodes are fabricated by blade coating method. Fluorescent blue host,1-(7-(9,9′-bianthracen-10-yl)- 9,9-dioctyl-9H-fluoren-2-yl)pyrene, and blue dopant, 4,4′-(1E,1′E)-2,2′-(naphthalene-2,6-diyl)bis(ethene-2,1-diyl)bis(N,N-bis(4-hexylphenyl)aniline), are used to achieve good solubility and pinhole-free thin film by solution process. The multilayer device structure with hole/electron transport layer is achieved by blade coating method without the dissolution problem between layers. The efficiency of the all-solution-processed device is 4.8 cd/A at 1200 cd/m², close to that by thermal deposition in high vacuum chamber. The device performance is optimized with the annealing temperature of TPBi layer at 50 °C.     

Tribological Performance of Two Potential Environmentally Friendly Ashless Vegetable Oil Additives

Two potential novel environmentally friendly ashless vegetable oil additives, 2-mercaptobenzothiazole derivatives, di-n-dodecyl-[2-(2-benzothiazolyl)thio]ethylborane (LBN) and di-n-dodecylthio-[2-(2-benzothiazolyl) thio]ethylborane (LBNS), were synthesized and their tribological performance as additives in rapeseed oil (RSO) was evaluated using a four-ball wear tester. Their anti-corrosive properties and thermal stability were also examined. The worn surface of the steel ball was analyzed by means of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results showed that 2-mercaptobenzothiazole derivatives exhibited excellent anti-corrosive property and high thermal stability. Moreover, they both had good load-carrying capacities and anti-wear and friction-reducing properties. The PB values of samples decreased in the following order: LBNS> LBN>RSO. The results of XPS examination illustrated that the excellent tribological behavior of the prepared compounds used as additives in RSO was attributed to the formation of a protective lubrication film on the worn surface, which consisted of an adsorption layer and a reaction layer containing Fe3O4, FeS, Fe2(SO4)3, FeB, and organic nitrogen-containing compounds.     

Synthesis of nano-sized biphasic calcium phosphate ceramics with spherical shape by flame spray pyrolysis

Nanometer size biphasic calcium phosphate (BCP) powders with various Ca/P molar ratios satisfied with appropriate phase ratios of HA/β-TCP were prepared by high temperature flame spray pyrolysis process. The BCP powders had spherical shapes and narrow size distributions irrespective of the ratios of Ca/P. The mean size of the BCP powders measured from the TEM image was 38 nm. The composition ratio of Ca/P was controlled from 1.500 to 1.723 in the spray solution, and required phase ratios of HA/TCP are controlled systematically. The calcium dissolution of the pellets obtained from the BCP powders directly prepared by flame spray pyrolysis in buffer solution increased with the decrease of Ca/P ratios except with the Ca/P ratio of 1.713. The pellet surface with Ca/P ratio of 1.500, which consisted of β-TCP, was eroded dramatically for 7 days. On the other hand, the pellet surface with Ca/P ratio of 1.667 was stable and did not disintegrate after immersion in Tris–HCl buffer solution based on the SEM observation.     

A numerical and experimental study of gap length on adhesively bonded aluminum double-lap joint

The elastic finite element analysis (FEA) and the experimental method were used to investigate the effect of the gap, as well as its length, on the stress distribution in both the mid-bondline and the adherend near the interface along the lap zone of adhesively bonded aluminum double-lap joint. The values of the peak stresses distributed in the mid-bondline were increased a little when an 8 mm length gap was arranged symmetrically around the center of the lap zone. Both peak stresses and stress at the point close to the edge of the gap in the mid-bondline were increased when the gap length was increased, but the increment of the peak stresses was small when the lap length was not greater than 16 mm. The results from the FEA simulation showed that the effect of the gap length on the ultimate load of the joint was small as the gap length was increased. It is supported with the results from the experiments that the ultimate load of the aluminum double-lap joint decreased a little when the gap length was less than 12 mm.     

诚信服务放心消费

推荐理由:随着中国电信行业的快速发展,各类业务层出不穷,客户规模迅速增加,行业的持续健康发展成为相关各方的关注重点,"诚信服务,放心消费"也成为电信行业可持续发展的重要内容.     

忻州市中型水库病险成因分析及加固对策

忻州市现有五座中型水库不同程度地存在防洪标准低，坝体填筑质量差，坝基、坝肩渗漏严重，观测、管理配套孕施不健全等问题，结合除险加固工程实践，通过对水库病险成因的分析，阐述了相应的加固措施。     

Identifying Language Origin of Named Entity With Multiple Information Sources

To identify the language origin of a named entity, morphological information associated with its letter spelling, such as letter N-grams, is commonly employed. However, with this information only, named entities with similar spellings but from different language origins are difficult to differentiate. In this paper, a measure of "popularity," in terms of frequency or page count of the named entity in language-specific Web search, is proposed for identifying its language origin. Morphological information, including letter or letter-chunk N-grams, is used to enhance the performance of language identification in conjunction with Web-based page counts. Six languages, including English, German, French, Portuguese, Chinese, and Japanese (Chinese and Japanese named entities are shown in their corresponding phonetic alphabets, i.e., Pinyin and Romaji), are tested. Experiments show that when classifying four Latin languages, including English, German, French, and Portuguese, which are written in Latin alphabets, features from different information sources yield substantial performance improvements in the classification accuracy over a letter 4-gram-based baseline system. The accuracy increases from 75.0% to 86.3%, or a 45.2% relative error reduction.