The k‐ϵ‐fP model applied to wind farms

The recently developed k‐?‐f_P eddy‐viscosity model is applied to one on‐shore and two off‐shore wind farms. The results are compared with power measurements and results of the standard k‐? eddy‐viscosity model. In addition, the wind direction uncertainty of the measurements is used to correct the model results with a Gaussian filter. The standard k‐? eddy‐viscosity model underpredicts the power deficit of the first downstream wind turbines, whereas the k‐?‐f_P eddy‐viscosity model shows a good agreement with the measurements. However, the difference in the power deficit predicted by the turbulence models becomes smaller for wind turbines that are located further downstream. Moreover, the difference between the capability of the turbulence models to estimate the wind farm efficiency reduces with increasing wind farm size and wind turbine spacing. Copyright © 2014 John Wiley & Sons, Ltd.     

Analysis of the Contribution of Adhesion and Hysteresis to Shoe–Floor Lubricated Friction in the Boundary Lubrication Regime

Slip and fall accidents cause frequent occupational injuries. Despite recent evidence that boundary lubrication is relevant to slipping, few studies have examined the mechanisms that contribute to shoe?Cfloor friction in this lubrication regime. This study aims to identify the contributions of adhesion and hysteresis to friction in boundary lubrication. Three shoe materials (40 Shore A hardness polyurethane, 60 Shore A hardness rubber, and 70 Shore A hardness rubber), two floor materials (vinyl and marble), and six lubricants (water, 1.5?% detergent, 25?% glycerol?C75?% water, 50?% glycerol?C50?% water, 75?% glycerol?C25?% water, and canola oil) were tested at a single sliding speed (0.01?m?s^?1). Dry adhesion and hysteresis were quantified for each of the shoe?Cfloor combinations and lubricated adhesion was quantified for all shoe?Cfloor-fluid combinations. The contribution of adhesion and hysteresis to shoe?Cfloor-lubricant friction was affected by both the shoe and floor material due to differences in hardness and roughness. Lubricated adhesion was complex and multifactorial with contributions from the shoe, fluid, shoe?Cfloor interaction, floor-lubricant interaction, and shoe-lubricant interactions. A simple regression model including two fluid coefficients and the dry adhesion friction force was able to predict 49?% of the lubricated adhesion friction variability.     

Analysis of cooperative MIMO transmission system with transmit antenna selection and selection combining

Error performance of a cooperative system can be enhanced by using transmit and receive diversity techniques at transmission links. The number of transmit/receive RF chain pairs required to achieve full diversity can be decreased to one for each link by using transmit antenna selection (TAS) method at the transmitter and selection combining (SC) method at the receiver. Thus, hardware complexity of a multiple input multiple output (MIMO) cooperative scheme can be significantly reduced when compared to systems that use TAS and maximum ratio combining (MRC). In this paper, we investigate the performance of an amplify‐and‐forward cooperative system where TAS/SC is utilized. We derive the probability density function (pdf) of end‐to‐end SNR of the system for Rayleigh fading channels. By using this pdf, we obtain the exact symbol error rate expressions for M‐PSK and M‐QAM modulations and the exact outage probability expression. We also obtain the asymptotical diversity order using upper and lower bounds of the outage probability expression and show that our system provides the same diversity order as the cooperative system where TAS/MRC is utilized. We verify our results via computer simulations. Copyright © 2010 John Wiley & Sons, Ltd.     

A Low-rate Data Transfer Technique for Compressed Voice Channels

This study considers the problem of transmitting generic (non-speech) data through compressed voice channels such as those used in wireless communications networks. These networks employ voice codecs that are designed to efficiently encode and reproduce the relatively slow-changing signals of human speech, which leads to communication channels that are nonlinear and have long-term memory. A data modem is presented that utilizes finite alphabets of waveforms that are numerically optimized to be as separable as possible after passing through the voice codec. The optimization of the finite alphabet is performed using a pattern search algorithm. When used with the GSM Enhanced Full-Rate Voice Codec, this system demonstrated improved performance, in terms of error rates, compared to previously reported results. Simulation results for four other voice codecs are also presented.     

Zusammenh?nge zwischen Verhalten und Fortpflanzungsleistung beim Reh (Capreolus capreolus L.)

Zusammenfassung Rehe leben in kleinen Verbänden von meist zwei bis fünt Tieren. Sie setzen sich zusammen aus einer adulten Geiß, ein, zwei oder drei Kitzen und einem Schmalreh. Vorübergehend halten sich auch ein oder zwei Böcke in dieser Mutterfamilie auf. Kurz vor der Setzzeit, welche Ende Mai oder Anfang Juni ihren Höhepunkt erreicht, trennen sich trächtige Weibchen von den übrigen Tieren. Die Größe ihres Wohnraumes wird kleiner und nimmt den Charakter eines Territoriums (Hediger, 1942) oder Reviers (Hennig, 1962) an. Während dieser territorialen Periode bekämpfen sich Muttertiere gegenseitig. Die Territorialzeit dauert bis Ende Juli. Während dieser Periode sind aggressive Auseinandersetzungen zwischen trächtigen oder führenden Weibchen häufig.Im Zentrum des Weibchenreviers liegen die Setz- und Aufzuchtplätze die Stellen, wo die Jungen geboren werden und dort für die ersten drei bis vier Lebenswochen liegen. In dieser Zeit begleiten sie ihre Mütter nicht. Sie werden nur aufgesucht zum Säugen und zum Putzen. Die Setz- und Aufzuchtplätze befinden sich häufiger an südexponierten Lagen als an anderen und vorwiegend in Heugraswiesen. In Gebieten mit verschiedener Populationsdichte konnte gefunden werden, daß mit Ansteigen der Wilddichte mehr und mehr Setzplätze an West-, Ost- und Nordexpositionen gefunden werden. Die Satzgröße (Anzahl der Kitze, welche von der gleichen Geiß aufgezogen werden) nimmt mit zunehmender Wilddichte ab. Das Geschlechterverhältnis verschiebt sich mit zunehmender Wilddichte und vor allem in nicht südlich gelegenen Expositionen zugunsten der Männchen. Anhand eines Modelles werden die gefundenen Zusammenhänge diskutiert.

---

Summary Roe deer live as solitary animals or in small bands of 2–5 individuals. The band consists of one adult female, one, two or three fawns and one subadult doe. From time to time one or two bucks live in these mother families. Shortly before the fawing season, which reaches its peak at the end of May or the beginning of June, the pregnant females separate themselves from the other animals. Their home ranges become smaller and take on the character of a territory (Hediger, 1942 andHennig, 1962). During the territorial period aggressive interactions are common among mother animals. The territorial period lasts until the end of July.In the center of the female territories are found the areas where the fawns are born and nursed during their first three or four weeks of life. During this period they do not accompany their mothers. They are only visited to be nursed and groomed. The areas where fawns are dropped and raised are most frequently on south facing slopes, normally in the hayfields. The denser the population becomes the more fawning areas are found in west, east and north facing slopes. The number of fawns produced by the same doe decreases with the increase in population density. With increasing population, more males than females survive especially in west, east and north facing slopes. The results are discussed.

---

Résumé Les chevreuils vivent en groupes peu importants de 2 à 5 animaux. Ces groupes sont formés d'un chevreuil femelle adulte (chevrette), de un ou deux voire trois jeunes (chevrillards) et d'un chevreuil femelle d'un an. A ces derniers peuvent encore s'ajouter de façon passagère un ou deux mâles. Peu avant la période des mises-bas, dont le point culminant se situe fin maidébut juin, les chevrettes gravides prennent leurs distances vis-à-vis des autres animaus. L'étendue de leur habitat se réduit et acquiert le le caractère d'un territoire (Hediger, 1942) ou d'une enceinte (Revier) (Hennig, 1962). Au cours de cette période de mises-bas, les chevrettes gravides ou suitées défendent leurs prérogatives territoriales par un comportement agressif.Au centre du territoire de la chevrette se trouve le lieu de mise-bas proprement dit («chambre» en terme de vénerie); c'est également à cet endroit que l'on trouvera les chevrillards pendant les 3 à 4 premières semaines de leur existence, période au cours de laquelle les chevrillards ne suivent pas encore leur mère et où celle-ci ne les visite que pour les allaiter ou pour les nettoyer. Ces «chambres» sont le plus souvent situées sur des versants Sud et dans des prés à foin. Lorsque la densité du chevreuil augmente, on constate toutefois une fréquentation croissante des versants exposés à l'Ouest, à l'Est et au Nord, de même qu'une diminution des naissances gémellaires. De plus, une densité croissante entraîne un glissement du rapport des sexes en faveur des mâles, en particulier sur les versants non exposés au Sud.

---

---

Mit Unterstützung des Schweiz. Nationalfonds und des Schweiz. Förderungsvereins des WWF.     

“山水心灯”上海世界博览会-台湾馆照明设计

在世界暖化以及能源短缺日趋严重的情况之下．节能减碳似乎已经或为了人类的共同目标,而在照明设计上,因应节能减碳的趋势．灯具节能、发光效率高．环保．寿命长成为了照明效果外的最重要诉求,对于照明设计来说,思考如何能够在节能省碳．预算以及最终效果上上达到平衡,便是一个非常重要的议题。因此本文藉由2010世博会-台湾馆照明设计之案例分析。由照明设计面切入节能的议题．实际带领各位了解整个台湾馆的照明设计,以照明节能理念融合台湾馆整体“山水心灯”的设计主轴,以“光”延续台湾馆的夜间美丽身影.     

Thrust stand for vertically oriented electric propulsion performance evaluation

A variation of a hanging pendulum thrust stand capable of measuring the performance of an electric thruster operating in the vertical orientation is presented. The vertical orientation of the thruster dictates that the thruster must be horizontally offset from the pendulum pivot arm, necessitating the use of a counterweight system to provide a neutrally stable system. Motion of the pendulum arm is transferred through a balance mechanism to a secondary arm on which deflection is measured. A noncontact light-based transducer is used to measure displacement of the secondary beam. The members experience very little friction, rotating on twisting torsional pivots with oscillatory motion attenuated by a passive, eddy-current damper. Displacement is calibrated using an in situ thrust calibration system. Thermal management and self-leveling systems are incorporated to mitigate thermal and mechanical drifts. Gravitational force and torsional spring constants associated with flexure pivots provide restoring moments. An analysis of the design indicates that the thrust measurement range spans roughly four decades, with the stand capable of measuring thrust up to 12 N for a 200 kg thruster and up to approximately 800 mN for a 10 kg thruster. Data obtained from calibration tests performed using a 26.8 lbm simulated thruster indicated a resolution of 1 mN on 100 mN level thrusts, while those tests conducted on a 200 lbm thruster yielded a resolution of roughly 2.5 mN at thrust levels of 0.5 N and greater.     

3D materials made of gold using Nanoimprint Lithography

In this work we show large area 3D stacking of gold structures like Split Ring Resonators (SRRs) and fishnet structures using Nanoimprint Lithography (NIL).Two main fabrication processes are used to stack multiple layers of such structures on top of each other: For the stacked fishnet structures a finished double-layer of gold structures is covered with a spacer layer which is planarized using chemical mechanical polishing so that a second layer can be processed on top. For the SRR structures a transfer printing process is used. Here the gold structures are transferred from one substrate onto another substrate. Especially this process is a new and unique possibility to stack gold patterns by transferring gold structures several time on the same substrate and therefore to build up 3D materials in a fast and cost efficient way.