FRP加强R/C梁防火性能调查研究

对纤维加强聚合物(FRP)材料加强钢筋混凝土梁在火灾中的防火性能进行了研究。试验结果显示,防火材料能够帮助构件达到标准防火性能,同时对不断增长的FRP应用也很重要。介绍了不同文献对FRP在高温下的性能所做的研究以及目前标准对建筑构件的耐火极限要求。对两个大型试验进行了介绍。试验材料为混凝土梁构件,外部用FRP板加强,并且三分之二用专利耐火隔热材料保护。给出了试验结果,并重点强调了曝火状态下所测得的构件温度。试验数据验证了热传导数值模型,该模型可用于预测加强并绝缘钢筋混凝土梁构件内的温度。试验结果和模型数据显示,正确设计和进行绝缘保护的FRP加强梁构件耐火极限能够达到4h或者以上。     

Investigation of Phase Stability in the System Sic-AlN

Dense samples of several compositions in the system SiC-AIN were fabricated by hot-pressing. The SiC-AIN powder was prepared by carbothermal reduction of an intimate mixture of alumina, silica, and carbon in a nitrogen atmosphere. X-ray diffraction and electron and optical microscopy were used to determine the chemical and microstructural characteristics of the hot-pressed specimens. Materials with bulk compositions between 15 and 75 wt% AIN were found to be nonhomo-geneous when hot-pressed below 2100°C. These materials were determined to be a mixture of SiC-AIN solid solutions with different compositions. The observed compositional variations were distinctly bimodal. The source of the in-homogeneity was the starting SiC-AIN powder. The powders, as well as the hot-pressed samples, consisted of a mixture of small crystals rich in SiC and large AIN-rich crystals. Compositions outside the 15 to 75 wt% AIN region were found to be single phase and to have the wurtzite structure. Hot-pressing SiC-AIN in the intermediate composition range at 2300°C produced an optically and chemically homogeneous material. The precipitation of an SiC-rich phase from a 75 wt% AIN solid solution and the precipitation of an AIN-rich phase from a 47 wt% AIN alloy when annealed at 1700°C are strong indications that a miscibility gas exists in the system SiC-AIN.     

On why constructivism does not yield relativism

Abstract

There are many varieties of epistemological and cognitive constructivism. They have in common an appreciation of the failures of centuries of attempts to realize a correspondence notion of truth and representation, and they all propose some constructivist programme as an alternative. The programmatic proposals, however, can differ greatly. Some contemporary constructivisms that are being vigorously advocated propose a social form of idealism with a consequent relativism. Such proposals risk giving constructivism a bad name. The main burden of this article is to show that such an idealism and relativism is not forced by constructivism, but, instead, is the result of an additional and questionable presupposition. Constructivism per se is a strong epistemological position that is fully compatible with realism.     

Possible common biomarkers from FTIR microspectroscopy of cervical cancer and melanoma

Detection of malignancy at early stages is crucial in cancer prevention and management. Fourier transform infrared (FTIR) spectroscopy has shown promise as a non‐invasive method with diagnostic potential in cancer detection. Studies were conducted with formalin‐fixed biopsies of melanoma and cervical cancer by FTIR microspectroscopy (FTIR‐MSP) to detect common biomarkers, which occurred in both types of cancer distinguishing them from the respective non‐malignant tissues. Both types of cancer are diagnosed on skin surfaces. The spectra were analysed for changes in levels of biomolecules such as RNA, DNA, phosphates and carbohydrate (glycogen). Whereas carbohydrate levels showed a good diagnostic potential for detection of cervical cancer, this was not the case for melanoma. However, variation of the RNA/DNA ratio as measured at I(1121)/I(1020) showed similar trends between non‐malignant and malignant tissues in both types of cancer. The ratio was higher for malignant tissues in both types of cancer.     

CATALYTIC PRODUCTION OF GRAPHITIC NANORODS VIA THE GAS PHASE DECOMPOSITION OF ETHYLENE OVER SUPPORTED NICKEL

The catalytic growth of high aspect ratio carbon nanorods by ethylene decomposition over nickel/silica is presented as a viable low-cost selective route to a high-value product. This study focuses on the role of catalyst preparation in determining carbon yield and structural characteristics and considers the application of a 10% w/w Ni loading prepared by impregnation and precipitation/deposition. The latter is characterized by a narrower dispersion of smaller Ni particles (average diameter?=?2.4?nm) but lower carbon yields. Doping this catalyst with KBr resulted in a 40-fold increase in carbon production with >95% having rod diameters <10?nm; doping the impregnated catalyst had little effect on catalyst performance. High-resolution transmission electron microscopy and temperature programmed oxidation were employed to characterize the catalysts and the carbon product; the effect of temperature (673–873?K) on carbon yield is also reported.     

EVALUATION OF PERFORMANCE OF THE 1 MW CERAMIC TUBE RECEIVER AT THE WEIZMANN INSTITUTE OF SCIENCE

Simulations were performed to evaluate the performance of a subsystem of the Thermochemical Pipeline Project (WITP) of the Weizmann Institute of Science. This subsystem includes a compressor, a 41 m long pipe, a cavity-type central receiver, and a mass-flow control element. The results show that the solar energy available for absorption into the tubes amounts to 1884 MWh/year, under the assumption that the working fluid (air) enters the cavity at 300 K and leaves at 1200 K. For bright days conditions, the average efficiency of the system increases from 56% (at 7 A.M. ) to 69% (at midday), with a yearly average efficiency of 63%. The mass flow is represented by the correlation:

where F_M is the total mass flow rate of the working fluid (kg/s(, and E_in is the total solar energy entering into the cavity (MW).

It is suggested to increase the performance of the receiver by: 1) exploiting a part of the solar power flux existing as spillage, and 2) capturing the energy of the hot air otherwise dissipated by convection.

It is suggested to increase the performance of the receiver by: 1) exploiting a part of the solar power flux existing as spillage, and 2) capturing the energy of the hot air otherwise dissipated by convection.     

PUTTING ARTISTS ON THE MAP: THE GEOGRAPHY OF ARTISTS IN CUYAHOGA COUNTY,OHIO

ABSTRACT: Across the country, urban leaders are developing arts‐focused urban policy, but much remains unknown about artists’ geography—particularly in contracting, rustbelt cities. Using Cuyahoga County, Ohio, this article describes the geography of artists and explores methodologies for predicting artist‐concentrated neighborhoods. The research questions if, and how, scholars can predict artist neighborhoods and design policies to support and nurture these locations. It maps and analyzes existing patterns using survey, property, and Census data, and predicts artist‐friendly neighborhoods via a regression model. The analysis reveals neighborhoods’ residual capacity for artists and directs initial policy recommendations for an artist‐focused vacant land reutilization initiative. For scholars, the findings contribute to a rapidly growing body of literature about the relationship between artists, neighborhood revitalization, and urban policy. For practitioners, the research investigates one strategy for shaping land policy in the post‐2008 housing market.