Wi-Fi fingerprinting based on collaborative confidence level training

Wi-Fi fingerprinting has been a popular indoor positioning technique with the advantage that infrastructures are readily available in most urban areas. However wireless signals are prone to fluctuation and noise, introducing errors in the final positioning result. This paper proposes a new fingerprint training method where a number of users train collaboratively and a confidence factor is generated for each fingerprint. Fingerprinting is carried out where potential fingerprints are extracted based on the confidence factor. Positioning accuracy improves by 40% when the new fingerprinting method is implemented and maximum error is reduced by 35%.     

基于语义相似度的Web信息可信分析

互联网上的虚假事实陈述严重影响人们有效地获取信息,如何判定事实陈述是否可信成为一个亟待解决的问题.文中提出了一种针对事实陈述的可信判定模型MFSV.该模型针对事实陈述的特点,从互联网上搜集与待判定事实陈述相关的文本信息,度量其与对应事实陈述的语义相似度;同时,该模型考虑了相关文本信息在可信度上的差别,从受欢迎程度和重要程度两个方面度量了相关文本信息来源的可信度,并获取了相关文本信息的可信度排序;根据语义相似度以及可信度排序,衡量了相关文本信息对对应事实陈述可信判定所做出的贡献,并以此为基础实现了待判定事实陈述的可信判定.一系列的实验验证了该模型的合理性及可信判定的准确性.     

Air pollution,economic spillovers,and urban growth in China

This paper empirically tests the interactive effects of air pollution and economic spillovers in Chinese cities from 2003 to 2010. The results show that Chinese cities benefit from the economic spillovers from surrounding cities, but bear the costs of negative air pollution externalities created by neighboring cities. We use wind direction and the administrative boundaries of provinces to disentangle possible multicollinearity between air pollution emissions and economic spillovers across cities. However, the results could not reject the growth-restricting effects of air pollution from neighboring cities. The results imply that the development of a city surrounded by polluters is likely to be constrained.     

Carboxylic acid mediated self-assembly of small molecules for organic thin film transistors

A p-type small molecule bearing dicarboxylic acid functional group (–COOH) is synthesized and evaluated for field-effect transistor properties. We discover and report for the first time, that the –COOH groups assist in the passivation of surface traps on the dielectric layer and simultaneously facilitate the self-assembly of the molecules via inter-molecular hydrogen bonding resulting in crystalline active channels. A 9-fold decrease in the threshold voltage was observed for the transistors made using the –COOH functionalized molecule, QT-DA, compared to its ester analogue, QT-ES, providing an evidence of surface passivation. This resulted in an increase in the hole mobility of QT-DA by up to 2 orders of magnitude. It was shown that QT-DA adopts a vertical alignment with respect to the substrate due to preferential interaction between the –COOH groups and the SiO₂ surfaces.     

Direct measurement method for plumb line deviations

The effect of irregularities of the refractive index of a terrestrial layer of the atmosphere on the slope of the polarization plane of an electromagnetic wave is evaluated numerically. An optical range polarimeter is developed having a sensitivity of the order of 1″. The possibility is demonstrated of practical application of the polarization plane as a basis for direct measurement of the relative angular positions (deviations) of a plumb line at scattered points of the earth’s surface.     

Spatial deprivation of urban public services in migrant enclaves under the context of a rapidly urbanizing China: An evaluation based on suburban Shanghai

The rapid economic growth of Chinese cities has attracted an increasingly migrant population. Faced with institutionalized discrimination caused by the Hukou system, however, rural migrants are excluded from local welfare, including certain types of urban public services. By taking suburban Shanghai as a case study, this research adopts the theoretical framework of urban deprivation and evaluates the deprivation level of migrant enclaves in terms of the provisions of public service, including educational, cultural, park, sports, healthcare, public transit, and postal service facilities through a combination of population census data, online and survey data. We then conducted questionnaire surveys and interviews in 14 migrant and local communities in order to acquire detailed socioeconomic information of residents and to understand their degree of satisfaction and information on how often they utilize public services. A multilevel regression model is run to examine the influence of indicators, including the socioeconomic status of respondents and provision of public services, on the degree of satisfaction. The paper concludes with policy implications needed to make spaces more socially equitable and inclusive in the rapidly urbanizing Chinese landscape.     

Supplementing an emissions tax by a feed-in tariff for renewable electricity to address learning spillovers

In the presence of learning spillovers related to renewable energy technologies, an optimal strategy to mitigate climate change should complement an emissions tax by a subsidy for renewables. This article addresses the question how such subsidy should be designed. It is shown that the widely-used approach of a revenue-neutral fixed feed-in tariff can yield an optimal outcome under restrictive conditions only. It has to be adapted continuously as the electricity price changes. Moreover, funding the tariff by a surcharge on the electricity price has important implications for the design of the emission tax. The optimal tax rate has to be below the Pigovian level, differentiated across fossil fuels and adapted over time as the patterns of technological development change. These requirements may pose a formidable challenge for practical decision-making. However, it is important to point out that the eventual choices made with respect to the design and funding of a feed-in tariff have to be based on a careful and more comprehensive policy assessment, including, inter alia, economic effects beyond the electricity sector and existing institutional constraints.     

A reliable and sensitive time-resolved fluorescent immunochromatographic assay (TRFICA) for ochratoxin A in agro-products

Immunochromatographic assays (ICAs) are considered as a suitable diagnostic tool for the detection of mycotoxins. Mycotoxins and especially, ochratoxin A are analytes with more demanding sensitivity requirements. To enhance the sensitivity of current immunochromatographic assays for ochratoxin A (OTA), a novel sensitive ICA was developed in this study. In the assay, microspheres enclosing fluorescent europium (III) [Eu(III)] nanoparticles (EuNPs) were used as a label for OTA monoclonal antibody (OTA-mAb) conjugation. Accordingly, assay was called time-resolved fluorescent immunochromatographic assay (TRFICA). The test strip was composed of three parts: a sample pad, nitrocellulose membrane and an absorbent pad. As for detection, a proper concentration of conjugated microspheres was pipetted into the microtube and sample extract was added to it. Then the strip was inserted into the tube and the fluid flow along the strip. The TRFICA results were obtained in 8 min and read by a portable TRFICA strip reader. The established method allows quantitative determination of OTA with limit of detection as low as 1.0 μg kg⁻¹ in the samples. For validation, spiked samples including wheat, maize, soybean and rice were respectively assayed by TRFICA and a standard high performance liquid chromatography equipped with a fluorescence detector (HPLC-FLD), and good agreement of results was obtained between two methods.     

A novel mechanical diced trench structure for warpage reduction in wafer level packaging process

The wafer warpage problem, mainly originated from coefficient of thermal expansion mismatch between the materials, becomes serious in wafer level packaging as large diameter wafer is adopted currently. The warpage poses threats to wafer handling, process qualities, and can also lead to serious reliability problems. In this paper, a novel mechanical diced trench structure was proposed to reduce the final wafer warpage. Deep patterned trenches with a depth about 100 μm were fabricated in the Si substrate by mechanical dicing method. Both experiment and simulation approaches were used to investigate the effect of the trenches on the wafer warpage and the influence of the geometry of the trenches was also studied. The results indicate that, by forming deep trenches, the stress on the individual die is decoupled and the total wafer warpage could be reduced. The final wafer warpage is closely related to the trench depth and die width. Trenched sample with a depth of 100 μm can decrease the wafer warpage by 51.4%.     

儿童福利机构社会工作标准化研究探析

本文从现阶段我国儿童福利机构社会工作状况入手,分析了机构内主要社会工作以及存在的问题,阐明了开展标准化工作的需求和条件,针对问题提出了儿童福利机构社会工作标准化途径。