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.     

Process parameters for hydrocooling apricots, plums, and peaches

Freshly harvested apricots, plums, and peaches in crates containing 5–20kg were hydrocooled in flowing water at 1°C and 50mms^-1. The cooling parameters: lag factor, cooling coefficient, and time to half-cool, determined from the exponential decline in the dimensionless ratio of temperature differences between fruit centre and coolant temperature at time t and at zero time, varied somewhat with crate load. Increasing the load from 5 to 20kg increased the time to half-cool apricots by 17% and plums and peaches by 39%.     

Prediction of Excess Air Factor in Automatic Feed Coal Burners by Processing of Flame Images

In this study, the relationship between the visual information gathered from the flame images and the excess air factor k in coal burners is investigated. In conventional coal burners the excess air factor k. can be obtained using very expensive air measurement instruments. The proposed method to predict k for a specific time in the coal burners consists of three distinct and consecutive stages; a) online flame images acquisition using a CCD camera, b) extraction meaningful information(flame intensity and brightness)from flame images, and c) learning these information(image features) with ANNs and estimate k. Six different feature extraction methods have been used: CDF of Blue Channel, Co-Occurrence Matrix, L_∞-Frobenius Norms,Radiant Energy Signal(RES), PCA and Wavelet. When compared prediction results, it has seen that the use of cooccurrence matrix with ANNs has the best performance(RMSE = 0.07) in terms of accuracy. The results show that the proposed predicting system using flame images can be preferred instead of using expensive devices to measure excess air factor in during combustion.     

Memory Partitioning in the Limit

International Journal of Parallel Programming - The key difficulties in designing memory hierarchies for future computing systems with extreme scale parallelism include (1) overcoming the design...     

玻璃光波导元件检测氯仿蒸汽的研究

利用旋转甩涂法在钾离子交换玻璃光波导表面上固定甲基绿/聚乙烯醇薄膜，成功地检测氯仿蒸汽。实验结果表明，该元件对氯仿蒸汽有良好的响应，其线性响应范围为10×10^-3-90×10^-3（R=0.98674）。该元件具有响应恢复速度快、可逆性好、成本低和易制备等特点。     

天山花楸叶抗菌作用研究

用一系列细菌和真菌试验了天山花楸叶乙醇提取物的抑菌作用。结果表明一定浓度的天山花楸叶乙醇提取物对供试细菌和真菌都显示出一定的抑制作用,MIC和MBC均较低,其抑菌活性随着提取物浓度的增大而逐渐增强。提取物对高温、紫外线都具有良好的稳定性。因此天山花楸叶乙醇提取物可用于食物防腐、保鲜等领域,具有广泛的使用范围。     

西伯利亚花楸枝条提取物抑菌作用的测定

为了研究西伯利亚花楸枝条乙醇提取物的体外抑菌特性,测定了提取物对一系列供试细菌和真菌的最低抑菌浓度、最低杀菌浓度,以金黄色葡萄球菌及大肠杆菌为例研究了提取物的热稳定性、紫外光稳定性,以金黄色葡萄球菌为例研究了提取物抑菌时间及抑菌率的关系,同时还进行了实物防腐实验.结果表明提取物对所有供试细菌及真菌都有明显的抑制作用,其最低抑菌浓度（MIC）较低;121℃湿热处理30min后,抑菌效应下降不大,具有良好的热稳定性及紫外光稳定性,其抑菌作用随抑菌时间的延长而增强,实物防腐实验效果良好.