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排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
972.
Mariaelena Tagliabue Osvaldo Da PosAndrea Spoto Giulio Vidotto 《Accident; analysis and prevention》2013
Riding a moped, like many other everyday activities, is a complex behavior in which attention plays a crucial role. This study aims to investigate the role of attention in enhancing the skills required to ride a moped simulator. Two experiments were conducted with 207 and 60 students (14–15 years old), respectively, using a moped simulator to ride on 12 different tracks. The assignment was to ride safely and avoid hazards. In experiment 1, we divided the hazard scenes of the tracks on the basis of the fact that a shift in attention was required to escape the danger. We showed that during the riding training, when no attentional shift was required, the ability to avoid hazards was constantly higher. In experiment 2, participants were asked to cope with the same basic experimental setting but with an additional attentive task. The results showed that they performed in such a way that not only did the attentive task not impair their performance, but it also produced an improvement in the ability to shift attentional focus, preserving performance efficiency. On the basis of these data, it can be claimed that, primarily, attentional shift plays a prominent role in accounting for accident circumstances. Secondarily, it can be claimed that attentional training contributes to improved processing efficiency so as to prevent mishaps. 相似文献
973.
Rate control has a critical influence on the video encoder design, and MB-level rate control is more flexible to control the spatial coding performance. However, most existing MB-level rate control methods are not designed for hardware implementation, and are too complex for practical use in real-time video coding. In this paper, a simple and effective MB-level rate control scheme is proposed that uses historical rate information to directly assign a QP value to a class of MBs. This paper will also introduce a method to realize the idea and make the pipeline data dependency applicable in circuit design. Experiments show that the proposed classification-based MB-level rate control algorithm can achieve a coding gain up to 0.6 dB and an averaging gain of 0.18 dB. 相似文献
974.
975.
Burak Felekoğlu Kamile Tosun Bülent Baradan Akın Altun 《Materials and Structures》2010,43(1-2):179-193
The effects of regional clinker porosity and interstitial phase morphology differences on grindability of clinkers have been investigated within the scope of this study. Porosity and phase characteristics of two clinkers from different furnaces which are using the same raw materials were determined by the application of image processing techniques on SEM images of polished surfaces. Comparison of interstitial phase compositions of two clinkers showed that, clinkers with similar phase compositions may have different grindability due to the porosity and phase morphology differences. Porous clinkers usually exhibit a dendritic interstitial phase morphology with an improved grindability. Increasing porosity also leads to greater incidence of the dendritic morphology in porous regions and lower incidence of alkali in the aluminate in dendritic regions. 相似文献
976.
Ibrahim Etem Saklakoğlu 《Journal of Materials Processing Technology》2009,209(4):1796-1802
Plasma immersion ion implantation (PIII) was used to implant nitrogen into Al at a temperature in the range of 320–520 °C. AlN phase was observed for temperatures above 450 °C, whereas no AIN detected by XRD diagnosis at temperatures below 380 °C. It was also observed that there was no effective increase in hardness of the material, but some wear resistance due to formation of AlN. 相似文献
977.
顺序表是一种常见的,用一组地址连续的存储单元依次存储数据元素的线性结构。在顺序表上进行查找有多种方法,其中最主要的是顺序查找和二分查找两种方法。用这两种方法实现学生成绩查询功能各有优缺点。 相似文献
978.
979.
Carla Da Porto Deborha Decorti Andrea Natolino 《International Journal of Food Science & Technology》2013,48(10):2127-2132
Conventional solvent extraction (CE) and ultrasound‐assisted extraction (UAE) in hexane for oil from untreated and enzyme‐treated grape seeds were investigated and compared. Among the output power tested (50, 100 and 150 W) in UAE on untreated seeds, UAE at 150 W for 30 min with liquid‐to‐solid ratio 8:1 (v/w) gave oil extraction yield comparable to CE (ca. 14% w/w) for 6 h with liquid‐to‐solid ratio 12:1 (v/w). CE and UAE at 150 W did not influence the fatty acid profiles of oil. CE oil was found to be the most oxidised. The enzymatic treatments (2, 4 and 6 g per 100 g seeds of Rapidase® Expression) prior to CE enhanced by 2.5% of the oil yield. Enzymatic treatments higher than 2 g per 100 g seeds increased relative value of some fatty acids both in CE and UAE. Enzymatic pretreatment from 2 to 4 g per 100 g seeds significantly improved some physicochemical parameters of oil quality when extracted by CE, but not by UAE. 相似文献
980.
Pınar Şen Fatih Dumludağ Bekir Salih Ali Rıza Özkaya Özer Bekaroğlu 《Synthetic Metals》2011,161(13-14):1245-1254
The new s-triazine-bridged trinuclear Zn(II) and Cu(II) phthalocyanines have been synthesized from the reaction of corresponding anhydrous metal salts, Zn(OAc)2 and CuCl with 4,5-bis(hexylthio)-phthalonitrile and 2,4,6-tris(2-thiophthalonitrile)-s-triazine. The tris phthalonitrile derivative of s-triazine was prepared from the reaction of 4-nitrophthalonitrile and thiocyanuric acid in dry dimethylformamide as solvent using K2CO3 as the base. The same route was applied to prepare the trinuclear Lu(III) phthalocyanine analogue. The conversion of tris phthalonitrile into its isoindoline derivative was accomplished by bubbling ammonia gas through a solution in methanol in the presence of sodium methoxide. The cyclization of two different isoindoline derivatives and 4,5-bis(hexylhthio)-1,2-diiminoisoindoline, with lutetium (III) acetate in dimethylformamide gave trinuclear Lu(III) phthalocyanine. The reaction of this complex with octakis-hexylthio phthalocyanine led to the isolation of tris double-decker Lu(III) phthalocyanine. The structures of the target compounds were confirmed by elemental analysis, UV–vis, IR and MALDI-TOF mass spectroscopies. The d.c. and a.c. conductivities of the phthalocyanine compounds were measured as a function of temperature. The small value of pre-exponential factor suggested the conduction by localized states in the band tails and by localized states near the Fermi level. The temperature dependence of the frequency exponent showed that the conduction in these compounds is due to hopping of charge carriers. The tris double-decker phthalocyanine complex showed well-defined electrochromic behaviour with green-blue and blue-purple colour transitions. 相似文献