552,087 research outputs found
Work on PETS Developed at CIEMAT
CIEMAT has been working on the RF power extractor so-called PETS (Power
Extraction and Transfer Structure) for the CLIC Test Facility 3 (CTF3) since
2007. The first contribution has been installed at the Test Beam Line (TBL).
Additionally, a new PETS configuration is presently under fabrication at CIEMAT
and will be installed in the Test Module at CTF3. This paper describes the PETS
prototypes design, fabrication and assembly techniques. The characterization of
the devices with low RF power is also described.Comment: 9 pages, 9 figures, 3 tables, 10 references. Work presented in the
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Study on Actuator Line Modeling of Two NREL 5-MW Wind Turbine Wakes
The wind turbine wakes impact the efficiency and lifespan of the wind farm. Therefore, to improve the wind plant performance, research on wind plant control is essential. The actuator line model (ALM) is proposed to simulate the wind turbine efficiently. This research investigates the National Renewable Energy Laboratory 5 Million Watts (NREL 5-MW) wind turbine wakes with Open Field Operation and Manipulation (OpenFOAM) using ALM. Firstly, a single NREL 5-MW turbine is simulated. The comparison of the power and thrust with Fatigue, Aerodynamics, Structures, and Turbulence (FAST) shows a good agreement below the rated wind speed. The information relating to wind turbine wakes is given in detail. The top working status is proved at the wind speed of 8 m/s and the downstream distance of more than 5 rotor diameters (5D). Secondly, another case with two NREL 5-MW wind turbines aligned is also carried out, in which 7D is validated as the optimum distance between the two turbines. The result also shows that the upstream wind turbine has an obvious influence on the downstream one
Racing car chassis
CĂlem tĂ©to bakalářskĂ© práce je analĂ˝za souÄŤasnĂ˝ch konceptĹŻ podvozkĹŻ závodnĂch okruhovĂ˝ch aut. V prvnà části práce je zpracován historickĂ˝ vĂ˝voj, charakteristika kol a pneumatik s reprezentacĂ dobĹ™e známĂ˝ch produktĹŻ. V druhĂ© části je popsán systĂ©m odpruĹľenĂ, pruĹľnĂ© mĂ©dia a tlumĂcĂ ÄŤleny. SystĂ©my odpruĹľenĂ je zde rozdÄ›len na nezávisle a polozávislĂ© zavěšenĂ kol a odpruĹľenĂ pevnĂ˝ch náprav. NásledujĂcĂ oddĂl tĂ©to práce je zaměřenĂ˝ na standardnĂ kontrolnĂ systĂ©my, jako jsou ABS, ESC a TSC. ZávÄ›r pĹ™inášà rychlĂ© shrnutĂ tĂ©to problematiky.The aim of this bachelor thesis is to analyse contemporary concepts of circuit race car chassis. In the first part of the thesis, the historical evolution is described and then wheels and tires characteristic within some well-known brand products are represented. The second important part includes the suspension systems, springing medium and damping members. The suspension systems are further divided to independent and semi-independent solutions and rigid axle suspensions. The end of this thesis deals with the standard braking control systems, such as ABS, ESC and TCS. The conclusion brings the quick summary of this subject.
Optimal line length for reading schoolbook on screen
Although experimental studies have shown a strong impact of text layout on the legibility of e- text, many digital texts appearing in eBook or the internet use different designs, so that there is no straightforward answer in the literature over which one to follow when designing e- material. Therefore, in this paper we shall focus on the text layout, particularly the influence of line lengthen reading performance of e-school book.48 native Arabic students (24 male and 24 female) volunteered for this experiment. The participants’ age ranged from 9 to 13. Performance of students was assessed through two dependent variables: (1) time to complete each tasks; and (2) accuracy of the answers. Accuracy data was based on the number of correct answers the students provided and the total score was 12 points. Several findings were reported by this experiment such as; the time needed to complete all the question models becomes significantly low when students are older, errors for all the question models are expected to be significantly lower for older students. Reading text on a single column with double columns shows that the reading process is affected by the students’ age, as older students were faster when reading through double columns, while students aged 9 prefer the single column in both reading processes. The study has recommended double line for fast reading for students their reading performance is satisfactory. While, long line has suggested for students with difficulty in reading
SAPPORO: A way to turn your graphics cards into a GRAPE-6
We present Sapporo, a library for performing high-precision gravitational
N-body simulations on NVIDIA Graphical Processing Units (GPUs). Our library
mimics the GRAPE-6 library, and N-body codes currently running on GRAPE-6 can
switch to Sapporo by a simple relinking of the library. The precision of our
library is comparable to that of GRAPE-6, even though internally the GPU
hardware is limited to single precision arithmetics. This limitation is
effectively overcome by emulating double precision for calculating the distance
between particles. The performance loss of this operation is small (< 20%)
compared to the advantage of being able to run at high precision. We tested the
library using several GRAPE-6-enabled N-body codes, in particular with Starlab
and phiGRAPE. We measured peak performance of 800 Gflop/s for running with 10^6
particles on a PC with four commercial G92 architecture GPUs (two GeForce
9800GX2). As a production test, we simulated a 32k Plummer model with equal
mass stars well beyond core collapse. The simulation took 41 days, during which
the mean performance was 113 Gflop/s. The GPU did not show any problems from
running in a production environment for such an extended period of time.Comment: 13 pages, 9 figures, accepted to New Astronom
An integrated circuit for chip-based analysis of enzyme kinetics and metabolite quantification
We have created a novel chip-based diagnostic tools based upon quantification of metabolites using enzymes specific for their chemical conversion. Using this device we show for the first time that a solid-state circuit can be used to measure enzyme kinetics and calculate the Michaelis-Menten constant. Substrate concentration dependency of enzyme reaction rates is central to this aim. Ion-sensitive field effect transistors (ISFET) are excellent transducers for biosensing applications that are reliant upon enzyme assays, especially since they can be fabricated using mainstream microelectronics technology to ensure low unit cost, mass-manufacture, scaling to make many sensors and straightforward miniaturisation for use in point-of-care devices. Here, we describe an integrated ISFET array comprising 216 sensors. The device was fabricated with a complementary metal oxide semiconductor (CMOS) process. Unlike traditional CMOS ISFET sensors that use the Si3N4 passivation of the foundry for ion detection, the device reported here was processed with a layer of Ta2O5 that increased the detection sensitivity to 45 mV/pH unit at the sensor readout. The drift was reduced to 0.8 mV/hour with a linear pH response between pH 2 – 12. A high-speed instrumentation system capable of acquiring nearly 500 fps was developed to stream out the data. The device was then used to measure glucose concentration through the activity of hexokinase in the range of 0.05 mM – 231 mM, encompassing glucose’s physiological range in blood. Localised and temporal enzyme kinetics of hexokinase was studied in detail. These results present a roadmap towards a viable personal metabolome machine
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