小南海水电站左岸溢流坝抗滑稳定分析

小南海水电站左岸溢流坝坝基内发育有层间剪切带、地层挠曲、顺河向的长大裂隙等,使其存在抗滑稳定问题。经分析该坝段的工程地质条件,确定坝基中可能出现的深层滑动破坏模式后,分别运用刚体极限平衡法和基于FLAC 3D的强度折减法计算坝基抗滑稳定安全系数,对比分析两种方法的计算成果。由强度折减法计算所得的安全系数均高于混凝土重力坝设计规范中规定的安全系数1.10,表明坝基的可能破坏模式不会发生,而刚体极限平衡法所得安全系数较强度折减法偏小,表明坝基的双斜滑动失稳模式可能发生,需要引起注意。但是对于不同的下游反向缓倾角裂隙倾角,两种方法所得安全系数的关系曲线变化趋势是一样的,倾角为40°时安全系数最小。     

Improvement of Mechanical Properties of Unsaturated Polyesters by Acrylonitrile

Propylene glycol- and diethylene glycol-based unsaturated polyesters were prepared and hardened by using styrene and acrylonitrile monomer mixtures. The addition of 12% acrylonitrile to a propylene glycol-based polyester containing 40% styrene increased the hardness from 12 BHN to 26 BHN. The addition of 20% acrylonitrile increased the impact strength of the same polyester from 14 J/m width to 39 J/m width. The diethylene glycol-based polyester containing 40% styrene and 40% acrylonitrile achieved a hardness of 23 BHN and an impact strength of 59 J/m width.     

Changes in quality parameters of Monterey sardine (Sardinops sagax caerulea) muscle during the canning process

Quality of fresh Monterey sardine (Sardinops sagax caeurela) muscle intended for canning was assessed in a local Mexican plant. Postharvest and processing times and temperatures were monitored at five different processing stages, in order to evaluate their impact on product quality and to compare their biochemical vs. their chronological age. Postmortem muscle spoilage indices were analysed (pH, nitrogen from total volatile bases, trimethylamine, histamine, peroxide value, and thiobarbituric acid-reactive substances) and the K value was analysed as the freshness indicator. Inadequate temperature increments were detected during the canning process. Spoilage indices remained constant throughout the process, indicating that no deterioration occurred in the raw material. Concerning the K value, although sardine showed a good quality for canning, its freshness reduction occurred three times faster than would otherwise occur under optimum handling conditions (0 °C), thus affecting (increasing) its biochemical age. Actual sardine management and treatment by the processor require better control during the canning process, thus reducing their impact on the freshness and biochemical age of sardine intended for this process.     

Influence of straining and ageing on the room temperature mechanical properties of dual phase steel

In this work, changes in mechanical properties in dual phase steel containing 20% martensite volume fractions were observed at various ageing temperatures. For example, ΔY (increase in yield strength due to strain ageing), YS and UTS exhibit maximum values at ageing temperature of 100 °C for the pre-strains of 2 and 4%. This is due to the formation of solute atom atmospheres around dislocation. When the ageing temperature increased to 200 °C, yield strength decreased due to overageing resulted from tempering that starts in martensite phase.     

Research on ethanol production and use from sugar beet in Turkey

Emissions of greenhouse gases such as CO₂, CO, CH₄ and NO_X from fossil fuel use are implicated in climate change. The use of bioethanol is one means to reduce fossil fuel use and emissions of greenhouse gases. This study investigated research to produce ethanol from sugar beet and use as fuel in Turkey. The calculated demand for bioethanol amounted to some 220,000 m³ where a 5% ethanol mix in petrol was used. Turkey has the potential to produce 30 million ton of sugar beet, which is sufficient to meet the bioethanol demand.     

Weibull renewal equation solution

The existing solution methods for the Weibull Renewal Equation suffer from a lack of sufficient accuracy due to the singularity at the origin for some parameter values of the weibull density. The proposed method of solution provides accuracy to any desired degree of precision for all parameter values particularly in the singular range. The method utilizes a cubic spline approximation of the unknown renewal function and applies the Galerkin technique of integral equation solution. Gaussian quadratures are used to evaluate integrals. The singular nature of the integrand is handled by the Gauss-Jacobi quadrature. Results are compared with those obtained by simulation.     

Processing of urea‐formaldehyde‐based particleboard from hazelnut shell and improvement of its fire and water resistance

The purpose of this study was to manufacture urea‐formaldehyde‐based particleboard from hazelnut shell and eliminate its disadvantages such as flammability, water absorption, swelling thickness by using fly ash and phenol‐formaldehyde. Synthesized urea‐formaldehyde and grained hazelnut shells were blended at different ratios ranging from 0.8 to 3.2 hazelnut shell/urea‐formaldehyde and dried at 70°C in an oven until constant weight was reached. In addition, other parameters affecting polymer composite particleboard from hazelnut shell and urea‐formaldehyde were investigated to be the amount of fly ash, amount of phenol formaldehyde and the effects of these parameters on bending stress, limit oxygen index, water absorption capacity and swelling in the thickness. The optimization results showed that the maximum bending strength was 4.1N/mm², at urea‐formaldehyde ratio of 1.0, reaction temperature of 70°C, reaction time of 25 min, hazelnut shell/urea‐formaldehyde resin of 2.4 and mean particle size of 0.1 mm. Although the limited oxygen index and smoke density of composite particleboard without fly ash has 22.3 and 1.62, with fly ash of 16% (w/w) according to the filler has 38.2 and 1.47, respectively. Water absorption and increase in the swelling thickness exponentially decreased with increasing phenol formaldehyde. Copyright © 2009 John Wiley & Sons, Ltd.     

The impact of a realistic packet traffic model on the performance of surveillance wireless sensor networks

It is quite common to see that classical periodic or Poisson packet traffic models are used for evaluating the performance of wireless sensor networks (WSNs). However, these models may not be appropriate for modeling the data traffic resulting from a particular application. Furthermore, they may be overestimating the performance of a WSN. In this paper, we show the significance of using a realistic and application-specific packet traffic model by comparing the performance of a well-known WSN protocol under the Surveillance WSN packet traffic model (SPTM), as well as under periodic and binomial traffic models. A packet traffic framework specific to surveillance applications is proposed which is then used for deriving SPTM analytically. In order to be adaptable and flexible, SPTM incorporates a probabilistic and parametric sensor detection model. Simulation results show that to employ an application-specific packet traffic model has significant impact on the performance evaluation of the WSN and ordinary traffic models may overestimate the capacity of the WSN.