Cold fusion | EPFL Graph Search

Cold fusion is a hypothesized type of nuclear reaction that would occur at, or near, room temperature. It would contrast starkly with the "hot" fusion that is known to take place naturally within stars and artificially in hydrogen bombs and prototype fusion reactors under immense pressure and at temperatures of millions of degrees, and be distinguished from muon-catalyzed fusion. There is currently no accepted theoretical model that would allow cold fusion to occur. In 1989, two electrochemists, Martin Fleischmann and Stanley Pons, reported that their apparatus had produced anomalous heat ("excess heat") of a magnitude they asserted would defy explanation except in terms of nuclear processes. They further reported measuring small amounts of nuclear reaction byproducts, including neutrons and tritium. The small tabletop experiment involved electrolysis of heavy water on the surface of a palladium (Pd) electrode. The reported results received wide media attention and raised hopes of a

Pulse plating of Ni-W alloys from model electrolytes

Dieter Landolt

Pulse plating of nickel-tungsten alloys has been studied from two citrate ammonia based model electrolytes containing either an excess of nickel or an excess of tungsten. The alloy composition and current efficiency were determined for pulse periods ranging from 1 ms to 50 s at a constant duty cycle of 0.4. Deposits were analysed by X-ray fluorescence and by gravimetry. In the nickel rich electrolyte the rate of co-deposition of tungsten was found to be controlled by mass transport as previously observed with Ni-Mo alloys. In the tungsten rich electrolyte the tungsten concentration in the deposited alloys was the highest at short pulse periods. This suggests that the deposition rate of tungsten was affected by the rate of transport of nickel which is the highest at short times. As the pulse on time exceeded the transition time for nickel the current efficiency for alloy deposition dropped owing to hydrogen formation.

2008

Implementing Fusion Techniques for the Classification of Paralinguistic Information

Jilt Sebastian

This work tests several classification techniques and acoustic features and further combines them using late fusion to classify paralinguistic information for the ComParE 2018 challenge. We use Multiple Linear Regression (MLR) with Ordinary Least Squares (OLS) analysis to select the most informative features for Self-Assessed Affect (SSA) sub-Challenge. We also propose to use raw-waveform convolutional neural networks (CNN) in the context of three paralinguistic sub-challenges. By using combined evaluation split for estimating codebook, we obtain better representation for Bag-of-Audio-Words approach. We preprocess the speech to vocalized segments to improve classification performance. For fusion of our leading classification techniques, we use weighted late fusion approach applied for confidence scores. We use two mismatched evaluation phases by exchanging the training and development sets, and this estimates the optimal fusion weight. Weighted late fusion provides better performance on development sets in comparison with baseline techniques. Raw-waveform techniques perform comparable to the baseline.

ISCA-INT SPEECH COMMUNICATION ASSOC2018

Scrape-off layer simulations in a Double Null magnetic configuration

Carrie Fiona Beadle, Paola Paruta, Paolo Ricci, Fabio Riva, Christoph Wersal

Different magnetic geometries are being considered for handling the power exhaust in DEMO, among which is the double-null. In addition to doubling the exhaust area, experiments have found stark differences in the SOL on the HFS and LFS in this configuration[1], allowing the possibility of efficient heating from the HFS in addition to doubling the exhaust area. The contrast between the LFS and HFS calls for theoretical investigation. In fact, the asymmetry can help to disentangle the different driving mechanisms of the turbulence. Since the temperature in the SOL is relatively low, the plasma is sufficiently collisional for a fluid model, such as the drift-reduced Braginskii, to be used. This model has been implemented in the GBS code[2],[3]. Focusing on limited geometries, the SOL width – a crucial quantity to determine the heat load on the plasma facing components – was estimated by identifying the driving linear instability and turbulence saturation mechanism[4]. The analytical and simulation results were validated against a large number of experiments, showing good agreement[5]. Recently, a non-field aligned coordinate system has been implemented in GBS. This avoids the coordinate singularity present for field-aligned coordinates at the X-point, thus allowing any toroidally symmetric magnetic field configuration to be simulated. We will introduce GBS, discuss the implementation of the new coordinate system and show results of the first simulations in a double-null magnetic configuration. We will present the first insights on the nature of SOL turbulence and the SOL width on the HFS and LFS. References [1] B. LaBombard, et al. Nuclear Fusion 55, 052020 [2015] [2] P. Ricci, et al, Plasma Physics and Controlled Fusion 54, 112103 [2012] [3] F. Halpern, et al, Journal of Computational Physics 315, 388 [2016] [4] A. Mosetto, et al, Physics of Plasmas 20, 092308 [2013] [5] F. D. Halpern, et al. Plasma Physics and Controlled Fusion 58, 084003 [2016]

2017

Scrape-off layer simulations in a Double Null magnetic configuration

Carrie Fiona Beadle, Paola Paruta, Paolo Ricci, Fabio Riva, Christoph Wersal

2017