基于数据挖掘的开源电子资源访问行为统计模型

为了解决当前图书馆资源个性化推荐过程中存在推荐的准确率、召回率以及效率较低的问题,采用二维距离模型构建用户社区模型,用于描述访问用户与图书馆开源电子资源之间的关系,并对互联网用户需求和访问行为进行模糊规则推理.依据互联网用户属性和图书馆资源访问需求属性之间的模糊规则,建立图书馆开源电子资源访问行为统计模型,并利用该模型向用户提供个性化推荐服务.仿真结果表明,所建模型的推荐召回率高达98. 4%,推荐准确率为99. 2%,运行时间小于0. 04 s.所建模型能够为互联网用户提供准确、高效地图书馆资源个性化推荐服务.     

上海市火力发电行业能源计量现状分析

能源计量与节能监测、能源审计、能源统计、能源利用状况分析是用能单位能源管理和节能工作的基础。通过对本市部分火力发电企业的现场调研，针对性地提出改进建议，以期帮助用能单位增强能源计量在节能减排工作中的有效性。     

Investigating measurements of fine particle (PM2.5) emissions from the cooking of meals and mitigating exposure using a cooker hood

There is growing awareness that indoor exposure to particulate matter with diameter ≤ 2.5 μm (PM_2.5) is associated with an increased risk of adverse health effects. Cooking is a key indoor source of PM_2.5 and an activity conducted daily in most homes. Population scale models can predict occupant exposures to PM_2.5, but these predictions are sensitive to the emission rates used. Reported emission rates are highly variable and are typically for the cooking of single ingredients and not full meals. Accordingly, there is a need to assess PM_2.5 emissions from the cooking of complete meals. Mean PM_2.5 emission rates and source strengths were measured for four complete meals. Temporal PM_2.5 concentrations and particle size distributions were recorded using an optical particle counter (OPC), and gravimetric sampling was used to determine calibration factors. Mean emission rates and source strengths varied between 0.54—3.7 mg/min and 15—68 mg, respectively, with 95% confidence. Using a cooker hood (apparent capture efficiency > 90%) and frying in non‐stick pans were found to significantly reduce emissions. OPC calibration factors varied between 1.5 and 5.0 showing that a single value cannot be used for all meals and that gravimetric sampling is necessary when measuring PM_2.5 concentrations in kitchens.     

Microstructural and Tribological Behavior of Pulse Electroplated Nickel Barrier on Copper Conductors

The microstructural, mechanical, and tribological behaviors of electroplated Ni on Cu conducting substrates have been investigated in this study. The microstructural studies were performed by X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). The results showed that initially (111) with (220), (200) Ni texture components were predominant in the coating, and increasing the current density from 0.1 to 0.5 A/cm² led to the development of a strong (111) texture. The presence of ultrafine grains coupled with a (111) Ni texture improved the coating microhardness and wear properties significantly. It was shown that with an increase in current density, wear resistance of the coatings improved significantly and the electrical resistivity increased due to the highly populated grain boundaries.     

Contribution of metal vapor mass at periphery part of pulsed arc to electromagnetic force in weld pool

The arc welding has been used in various welding methods because it is inexpensive and high in strength after welding. However, it is a problem that accidents such as collapse of the bridge occur because of the welding defects. The welding of low cost and high productivity is required without the welding defects. The pulsed TIG welding is inexpensive and capable of high‐quality welding. The electromagnetic force contributing to penetration changes because the transient response of arc temperature and iron vapor generated from anode occurs. However, the analysis of pulsed TIG welding with metal vapor has been elucidated only metal vapor concentration near anode with transient phenomenon and heat flux. Thus, the theoretical elucidation of penetration depth with control factor has not been researched. In this paper, the contribution of metal vapor mass at the periphery part of pulsed arc to the electromagnetic force in the weld pool is elucidated. As a result, the iron vapor mass at periphery part decreased with increasing the frequency. The iron vapor was stagnated at axial center within one cycle. The electromagnetic force to the penetration depth direction in weld pool increased at axial center. Therefore, the metal vapor mass at periphery part plays an important role for the electromagnetic force increment at axial center.     

The effect of optimized carbon source on the synthesis and composition of exopolysaccharides produced by Lactobacillus paracasei

This study aimed to predict the optimal carbon source for higher production of exopolysaccharides (EPS) by Lactobacillus paracasei TD 062, and to evaluate the effect of this carbon source on the production and monosaccharide composition of EPS. We evaluated the EPS production capacity of 20 strains of L. paracasei under the same conditions. We further investigated L. paracasei TD 062, which showed the highest EPS-producing activity (0.609 g/L), by examining the associated biosynthesis pathways for EPS. Genomics revealed that fructose, mannose, trehalose, glucose, galactose, and lactose were carbon sources that L. paracasei TD 062 could use to produce EPS. We identified an EPS synthesis gene cluster that could participate in transport, export, and sugar chain synthesis, and generate 6 sugar nucleotides. Experimental results showed that the sugar content of the EPS produced using fermentation with the optimized carbon source (fructose, mannose, trehalose, glucose, galactose, and lactose) increased by 115%. Furthermore, use of the optimized carbon source changed the monosaccharide content of the associated EPS. The results of enzyme activity measurements showed significant increases in the activity of 2 key enzymes involved in the glycoside synthesis pathway. Our study revealed that optimizing the carbon source provided for fermentation not only increased the production of EPS, but also affected the composition of the monosaccharides by increasing enzyme activity in the underlying synthesis pathways, suggesting an important role for carbon source in the production of EPS by L. paracasei TD 062.     

Microcrack healing in zirconia ceramics under a DC electric field/current

Flash event caused by a DC electric field/current was applied to the crack healing in 8 mol % Y₂O₃ stabilized cubic ZrO₂ polycrystals (8Y-CSZ). The flash event, which occurred by applying the DC power higher than a critical value of 100 mW/mm³, successfully healed the microcrack within several minutes without any healing agents at a furnace temperature of 800 °C. As compared to the healing treatment under static annealing, the healing phenomena were accelerated about 2 times under the flash treatment even at the same temperatures, suggesting that the enhanced healing phenomena cannot be explained only by the temperature effect. Since the rate of grain growth was accelerated under the flash treatment, the flash healing would be accelerated through the current-enhanced diffusional processes. This study shows for the first time that the flash event has a potential to apply to the crack healing process in the ceramic materials and composites.     

Modification of exposure conditions by the magnetic field configuration in helicon antenna-excited helium plasma

Modification of exposure conditions downstream in the diffusion chamber has been performed in helicon antenna-excited helium plasma by adjusting the magnetic field(intensity and geometry).In the inductively coupled mode(H mode), a reduction in ion and heat fluxes is found with increasing magnetic field intensity, which is further explained by the more highly magnetized ions off-axis around the last magnetic field lines(LMFL). However, in helicon wave mode(W mode), the increase in magnetic field intensity can dramatically increase the ion and heat fluxes.Moreover, the effect of LMFL geometry on exposure conditions is investigated. In H mode with contracting LMFL, off-axis peaks of both plasma density and electron temperature profiles shift radially inwards, bringing about a beam with better radial uniformity and higher ion and heat fluxes. In W mode, although higher ion and heat fluxes can be achieved with suppressed plasma cross-field diffusion under converging LMFL, the poor radial uniformity and a small beam diameter will limit the size of samples suitable for plasma irradiation experiments.     

南水北调中线水源区浮游植物群落结构 及其生物多样性

为探究南水北调中线水源区丹江口水库浮游植物群落结构变化及其生物多样性，于 2014—2015 年对丹江 口水库进行为期 1 年的调查和分析。发现浮游植物共 8 门 76 属 101 种，其中，绿藻门、蓝藻门及硅藻门占总种数 90.10%，绿藻门种类数最多（45 种），其次是蓝藻门（26 种）和硅藻门（20 种）。浮游植物群落结构随季节变化有所 不同：夏秋季节生物量明显高于冬春季节；优势种在冬季以颗粒直链藻、颗粒直链藻极狭变种、铜绿微囊藻和小 环藻为主，春季以球衣藻、薄甲藻属及小环藻为主，夏季以简单颤藻、单胞衣藻原变种和球衣藻为主，秋季以类颤 藻鱼腥藻、简单颤藻、球衣藻和小环藻为主。应用 Shannon-Wiener 多样性指数 H′、Pielou 均匀度指数 J′、Margalef 丰富度指数 Dm评价水质结果表明：丹江口水库夏秋季水体营养化程度更高。典型对应分析表明：水温、透明度、 总氮、总磷等是影响浮游植物群落结构的主要环境因子，夏秋季受温度影响蓝藻、绿藻数量逐渐增多，一定程度 上增加了受水区生态变化风险。本研究可为南水北调中线水源区丹江口水库生态环境变化及生物迁移风险提供 数据支持。     

Pulsed current-driven wetting of 3YSZ by liquid Cu and its mechanisms

The wettability of 3 mol% Y₂O₃-stabilized ZrO₂ (3YSZ) by molten Cu can be greatly improved by applying pulsed currents at 1373 K. The improvement was closely related to current polarity and influenced by duty cycle and frequency. When the Cu/3YSZ interface was under cathodic condition, the wettability was mainly improved by the formation of substoichiometric ZrO_2-δ and metallic Zr at the interface. Increasing duty cycle caused the interface to change from forming protrusions to creating depression. Decreasing frequency further deepened the depression. In the opposite polarity, the adsorption and enrichment of oxygen reduced the solid-liquid and liquid-vacuum interfacial energies, thus improving the wettability. Only bubbles formed at the interface. The larger the duty cycle, the more rapidly bubbles formed and escaped. The effect of frequency at this polarity was weak. Overall, this work provides a novel and effective strategy for tailoring the wettability and interfacial chemistry between zirconia and metals.