“Blind Test 3” calculations of the performance and wake development behind two in-line and offset model wind turbines

This is a report on the comparison between measurement data and predictions presented at the “Blind Test 3” Workshop organized jointly by Nowitech and Norcowe in Bergen, 10 and 11 December, 2013. A number of researchers were invited to predict the performances and the wake development behind two model wind turbines that have been extensively tested at the Department of Energy and Process Engineering, NTNU. The turbines were arranged in-line, but slightly offset so that the wake of the upstream turbine only interacted with roughly half the area swept by the second rotor. This is a common event in most wind parks and produces flow fields that are both complicated and harmful for the downstream turbine. As expected it turned out to be a difficult flow to predict.Contributions were received from five different groups using a range of methods, from fully resolved Reynolds averaged Computational Fluid Dynamics (CFD) models to Large Eddy Simulations (LES). The range of results was large but the overall trend is that the current methods predict the power generation as well as the thrust force reasonably well. But there is a large uncertainty in the prediction of the turbulence field in the wake. Hence, the LES method consistently performed better than the others.     

Detecting extensional viscosity of polypropylene melt using the Rheotens test: A comparison between standard and steady state test modes

The Rheotens test was used to determine the extensional viscosity of a polypropylene (PP) melt at three different extrusion velocities and using two capillaries with different length-to-diameter ratios. Results showed that, in the standard Rheotens test, the extensional viscosity curves determined under different testing conditions exhibit an obvious difference, especially under low extensional strain rates. This is attributed to the pre-orientation of macromolecular chains taking place in the capillary. Hence, a steady state Rheotens test was tentatively proposed. It was demonstrated that the extensional viscosity curves determined under most of the testing conditions by this test mode almost overlap, which is attributed to the fact that the pre-orientation of chains relaxes sufficiently near the capillary exit. This implies that equivalent extensional viscosities can be obtained under a wider range of extrusion velocities and capillary length-to-diameter ratios. Moreover, the equivalent extensional viscosities determined in the steady state Rheotens test exhibit good agreement with the extrapolated extensional viscosity curve determined using the Cogswell convergent flow method.     

Studies on Fluorescamine. Part II - Thin-Layer Chromatographic Mobilities of Fluorescamine Positive Drugs

Abstract

Fluorescamine reacts with primary amines, it does not react with secondary or tertiary amines, to yield bright acquamarine fluorescent products. This reaction has been developed into a spot test useful for differentiation of amphetamine from methamphetamine; previous spot tests did not have this degree of specificity. The fluorescent products of several primary amines have been demonstrated to have sufficient stability to permit thin-layer chromatography comparisons with authentic materials. The fluorescent derivative of amphetamine has been demonstrated to be capable of differentiation from other fluorescent products formed from fluorescamine based on its unique migration in three different TLC systems.     

Dynamic ice loads on conical structures

Two series of model tests were performed to observe the dynamic ice loads on conical structures. The variable testing parameters include the water line diameter of the model cone and ice parameters. During small water line diameter tests, two-time breaking is found to be the typical failure of ice on steep conical structure, and also be controlled by other factors, such as ice speed and the cone angle. During big water line diameter tests, the ice sheet failed nonsimultaneously around the cone. Several independent zones of bending were found in the nonsimultaneous failure process of ice. With the increase of the ratio of D/h and the number of independent zones, the total ice force was found being gradually reduced.     

Parameter change test for location‐scale time series models with heteroscedasticity based on bootstrap

This study considers the bootstrap cumulative sum (CUSUM) test for a parameter change in location‐scale time series models with heteroscedasticity. The CUSUM test has been popular for detecting an abrupt change in time series models because it performs well in many applications. However, it has severe size distortions in many situations. As a remedy, we consider the bootstrap CUSUM test, particularly focusing on the CUSUM test based on score vectors, and demonstrate the weak consistency of the bootstrap test for its justification. A simulation study and data analysis are conducted for illustration.     

Theoretical and experimental researches of size effect in micro-indentation test

Micro-indentation tests at scales on the order of sub-micron have shown that the measured hardness increases strongly with the indent depth or indent size decreasing, which is frequently referred to as the size effect. However, the trend is at odds with the size-independence implied by conventional elastic-plastic theory. In this paper, strain gradient plasticity theory is used to model the size effect for materials undergoing the micro-indenting. Meanwhile, the micro-indentation experiments for single crystal copper and single crystal aluminum are carried out. By the comparison of the theoretical predictions with experimental measurements, the micro-scale parameter of strain gradient plasticity theory is predicted, which is fallen into the region of 0.8–1.5 micron for the conventional metals such as copper (Cu), aluminum (Al) and silver (Ag). Moreover, the phenomena of the pile-up and sink-in near micro-indent boundary are investigated and analyzed in detail.     

Measurement of surface form deviation of the plane optical element using grid line method

A method for automatically measuring the surface form deviation of the plane optical element is presented. It uses the image pre-processing technique to obtain the centerlines of the interference fringes, the grid line technique to search the average fringe spacing and the maximum curvature of the interference fringes, and the normalization to obtain the value of surface form deviation of the optical element. The experimental results show that the measuring precision of the surface form deviation of the plane optical element reaches the value of 0.1 and the method improves the adaptation capability of processing the interference fringes, which indicates that the method can substitute the visual interpretation of interference fringes in high-noise workshop environment.     

医学显性致死试验平均死胎率比较的统计分析

负二项分布方法可用作比较显性致死试验中平均死胎率的差异 ,本文对传统的负二项分布方法进行了描述 ,同时提出两种非参数方法 ,且就以上的方法的不足进行了比较 ,例子显示利用文中的一种非参数方法—L法更为合理     

On large deviations in testing Ornstein–Uhlenbeck-type models

We obtain exact large deviation rates for the log-likelihood ratio in testing models with observed Ornstein–Uhlenbeck processes and get explicit rates of decrease for the error probabilities of Neyman–Pearson, Bayes, and minimax tests. Moreover, we give expressions for the rates of decrease for the error probabilities of Neyman–Pearson tests in models with observed processes solving affine stochastic delay differential equations.      

Utilization of TXRF analytical technique in order to improve front-end semiconductor processing

In this paper, we summarize how the introduction of in-line TXRF monitoring provides detailed analytical information on aluminum, titanium and molybdenum contamination levels in order to improve several process steps from front-end processing, minimize product yield loss and make it possible to successfully manufacture multiple products and process geometries in the same fabrication platform.