A Novel Approach for Bolted T-Stub Connections

This paper reports an investigation into new connection types and their behaviors determined using full-scale experiments. T-shaped connections were created using the IPE standard profile. The aim of this study was to analyze the influence of T connections based on the IPE standard profile, height of beam to height of T-stub joint (H) of T-stub joints, and lengths (X) of T-stub joints on the behavior of steel connections, in order to provide the necessary data for improving Eurocode 3 and enable efficient use of residue IPE standard profiles and back to the consumption cycle. While the moment resistance values increased with an increase in H from H_min to H_max in model groups with X of 126 mm, and the energy dissipation increased with an increase in H from H_min to H_max and also with an increase in the lengths (X) of T-stub joints from 54 to 126 mm.     

Analysis of cross-country variations in the depth of European mortgage markets

To date, quantitative analysis on the depth of mortgage markets across a broad set of countries has been very limited. This paper uses a rich and balanced data set on 31 European countries to investigate the cross-country variations in the depth of mortgage markets during the period 2005–2012. The present paper might be accepted as the updated and enriched version of existing research for the European region in terms of the coverage of countries, historical data and the empirical analyses. Our empirical findings reveal that developed countries have sizeable residential mortgage markets and this is mainly associated with higher urbanization rates and stronger legal rights. One of the most notable results of this study is that, statistical significance of explanatory variables in modeling the depth of the mortgage markets depends heavily on both the variables, countries (regions) included in the models and the regression methodology used. Hence, we argue that strong conclusions based on such analyses should be avoided and the findings of previous research on the variations of the depth of mortgage markets should be carefully evaluated.     

On using available environmental data in service life estimations

In the process of service life prediction or estimation of building and construction components and materials, data of the prevailing exposure environment, (the conditions at and around a building or construction) is required. However, most environmental data is measured by and available from meteorological and air quality research communities. This data is collected at macro and meso levels, some distance from the object studied, and raises the need to transform data in order to describe the specific, local conditions adjacent to that object. To estimate levels of degradation agents in the exposure environment, especially those close to the building or construction at local and micro levels have to be considered. This paper will show and discuss useful environmental data sources, and how to transform such data by means of available distribution models.

Lorsqu'il s'agit de faire des prévisions ou des estimations de durée de vie de bâtiments ainsi que de composants et matériaux de construction, il faut disposer des données sur les conditions prévalantes d'exposition et d'environnement (conditions qui règnent dans un bâtiment ou à proximité). Or, la plupart des données environnementales sont mesurées et fournies par des instituts de recherche en météorologie et qualité de l'air. Ces données sont collectées à grande et à moyenne échelle, à une certaine distance de l'objet étudié, et elles doivent donc être transformées si l'on veut décrire les conditions spécifiques locales à proximité dudit objet. Pour estimer le niveau de dégradation dans l'environnement d'exposition, notamment à proximité des bâtiments ou constructions, il faut considérer les agents au micro-niveau et au niveau local. Cet article présente et examine des sources de données environnementales utiles et montre comment transformer ces données en utilisant les modèles de distribution existants.     

The statistical modeling of surface roughness in high-speed flat end milling

Surface roughness is one of the most important requirements in machining process. The surface roughness value is a result of the tool wear. When tool wear increase, the surface roughness also increases. The determination of the sufficient cutting parameters is a very important process obtained by means of both minimum surface roughness values and long tool life. The statistical models were developed to predict the surface roughness.This paper presents the development of a statistical model for surface roughness estimation in a high-speed flat end milling process under wet cutting conditions, using machining variables such as spindle speed, feed rate, depth of cut, and step over. First- and second-order models were developed using experimental results of a rotatable central composite design, and assessed by means of various statistical tests. The highest coefficient of correlation (R_adj²) (88%) was obtained with a 10-parameter second-order model. Meanwhile, a time trend was observed in residual values between model predictions and experimental data, reflecting the probable effect of the tool wear on surface roughness. Thus, in order to enhance the estimation capability of the model, another independent variable was included into the model to account for the effect of the tool wear, and the total operating time of the tool was selected as the most suitable variable for this purpose. By inserting this new variable as a linear term into the model, R_adj² was increased to 94% and a good fit was observed between the model predictions and supplementary experimental data.In this study, it was observed that, the order of significance of the main variables is as X₅>X₃>X₄>X₁>X₂ (total machining time, depth of cut, step over, spindle speed and feed rate, respectively).     

Studies on synthesis,characterization, and metal adsorption of mimosa and valonia tannin resins

A few thermosetting wood adhesive tannin resin system from formaldehyde reaction with both condensed and hydrolysable tannin has been developed. Polymerization of formaldehyde with mimosa tannin and valonia tannin was carried out at optimal conditions obtained from literature to establish the adhesive resin formulation. Formed reaction products were characterized by FTIR spectroscopy. The possible adsorption mechanisms for the adsorption of various metal ions onto tannin‐formaldehyde resins were proposed. Also, thermal analysis were studied and discussed by differential scanning calorimetry and thermogravimetry. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 786–797, 2006     

Friction and Wear Characteristics of Haynes 25, 188, and 214 Superalloys Against Hastelloy X up to 540 <Emphasis Type=Bold>°</Emphasis>C

As demand for more power increases, compression ratios, and operating temperatures keep rising. High speeds combined with high temperatures make turbomachinery sealing applications even more challenging. In order to confirm sufficient service life material pairs should be tested under conditions similar to engine operating conditions. This study presents high temperature friction and wear characteristics of cobalt/nickel superalloys, Haynes 25 (51Co–10Ni–20Cr–15W), Haynes 188 (39Co–22Ni–22Cr–14W), and Haynes 214 (75Ni–16Cr–3Fe–0.5Mn) sheets when rubbed against Hastelloy X (47Ni–22Cr–18Fe–9Mo) pins. Tests are conducted at 25, 200, 400, and 540 °C with a validated custom design linear reciprocating tribometer. Sliding speed and sliding distance are 1 Hz and 1.2 km, respectively. Friction coefficients are calculated with friction force data acquired from a load cell. Wear coefficients are calculated through weight loss measurements. Results indicate that Haynes 25 (H25) has the lowest friction coefficients at all test temperatures. Above 400 °C, H25 and Haynes 188 (H188) exhibit the best wear resistance. Protective cobalt oxide layers are formed on the H25 and H188 at 540 °C in addition to nickel, chrome, and tungsten oxides. Although, it has better oxidation resistance, Haynes 214 has relatively higher wear rates than other tested materials especially at low temperatures. However, its wear performance improves beyond 200 °C.     

Optimizing Leakage Energy Consumption in Cache Bitlines

As technology scales down into deep-submicron, leakage energy is becoming a dominant source of energy consumption. Leakage energy is generally proportional to the area of a circuit and caches constitute a large portion of the die area. Therefore, there has been much effort to reduce leakage energy in caches. Most techniques have been targeted at cell leakage energy optimization. Bitline leakage energy is critical as well. To this end, we propose a predictive precharging scheme to reduce bitline leakage energy consumption. Results show that energy savings are significant with little performance degradation. Also, our predictive precharging is more beneficial in more aggressively scaled technologies.     

二联噻吩和联苯胺类交替共聚物的合成及表征

以联苯二胺及二甲基联苯二胺为原料,合成了相应的N,N′-二氯联苯醌胺单体,并以二价镍配合物为催化剂与二连噻吩共聚得到了相应的交替共聚物。所得聚合物通过FT-IR,1H-NMR进行了表征。所得聚合物紫外-可见光谱分别在330、437、327、410nm处最大吸收峰出现。所得聚合物在-0.1～0.8V之间进行循环伏安分析,每一个聚合物都观察到两对氧化峰和还原峰分别在(Epa=0.40V/Epc=0.31V和Epa=0.70V/Epc=0.56V)和(Epa=0.33V/Epc=0.28V和Epa=0.63V/Epc=0.50V)。     

核桃隔膜总黄酮和微量元素的测定

本实验采用分光光度法测定了核桃隔膜中总黄酮的含量,黄酮总含量为6.259%(62.59mg/g),微量元素的测定采用了火焰原子吸收法,10种微量元素含量分别为Na5.69×102μg/g、K6.95×103μg/g、Ca6.22×102μg/g、Mg6.10×102μg/g、Zn6.10μg/g、Fe1.20×102μg/g、Cu2.03μg/g、Co<0.05μg/g、Ni6.10μg/g、Mn16.27μg/g。总黄酮是最新发现的一种激发脑潜能的物质,它能有效地激发脑活力,对提高青少年智力产生积极作用,并且能有效抑制成人及老年人脑功能衰退。