Porous materials have attracted considerable attention from researchers due to its many uses in molecular separation, heterogeneous catalysis, absorption technologies, and electronic improvements. These solid material...
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Human brains and bodies are not hardware running software: the hardware is the software. We reason that because the microscopic physics of artificial-intelligence hardware and of human biological "hardware" ...
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Adsorption equilibrium and kinetics of CO2, H2 and CH4 on zeolite 13 X were carried out using the volumetric method. The zeolite 13 X was characterized via XRD, SEM and N2 adsorption-desorption. Adsorption isotherms o...
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Traditional randomized clinical trials are regarded as the gold standard for assessing the efficacy of chemotherapy. However, this procedure has drawbacks such as high cost, time consumption, and limited patient explo...
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Lightning is responsible for both human and economic loss but its prediction remains challenging. We seek to find a lightning prediction model in South Africa that uses historical lightning-flash data only. This type ...
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ISBN:
(纸本)9781665440677;9781665411608
Lightning is responsible for both human and economic loss but its prediction remains challenging. We seek to find a lightning prediction model in South Africa that uses historical lightning-flash data only. This type of prediction model is cost-effective, easy to interpret and may be used for realtime forecasting. We evaluated and compared three popular time-series machine learning techniques on their ability to predict the number of Cloud-to-ground lightning flashes in South Africa for three-hours ahead. These models are the Auto Regressive (AR), Auto Regressive Integrated Moving Average (ARIMA) and the Long-Short-Term-Memory Recurrent Neural Network (LSTM) models. We used historical lightning data from the South African Lightning Detection Network during 2018. Our prediction model parameters were AR(lag=8), ARIMA (AR lag=8, Integrate=0, MA lag=2) and LSTM (2x50 layers, activation=ReLU, optimizer=adam) and models were minimized for Root Mean Square Error but evaluated based on Mean Absolute Percentage Error (MAPE). We used a 70%/30% Train-test split. The AR and ARIMA models performed comparably with a MAPE of 15312 and 15080 respectively. The LSTM Model outperformed considerably with a MAPE of 3705. Although the LSTM model outperformed, predictions errors in absolute terms were still high. This paper highlights the usefulness of nonparametric predictions models for lightning prediction.
A radiative shock(RS) is one in which the density and temperature structures are affected by radiation from the shock-heated matter. RS plays a special role in astrophysics as it nontrivially combines both hydrodynami...
A radiative shock(RS) is one in which the density and temperature structures are affected by radiation from the shock-heated matter. RS plays a special role in astrophysics as it nontrivially combines both hydrodynamics and radiation physics. In most astrophysical shocks, the temperature and density conditions lead to strong emission, with radiation thus playing a major role therein. Various RS structures can be implied for numerous astrophysical objects, such as supernova explosions, stellar interiors [1],stellar winds, star formation, black hole accretion disks [2], accreting neutron stars [3], and gamma-ray bursts [4]. In particular, RS exists in the blast waves of core-collapse supernovae(CCSNe),where the radiation pressure in matter is larger than the thermal one. On the basis of multi-messenger supernova observations, their explosion model and particle acceleration mechanisms have been built, and the characteristics of progenitor stars can be further constrained. However, entire supernova explosions are very difficult to model numerically because of the different spatial and temporal length scales involved and the controversial neutrino-driven mechanism [5].
By replacing the internal energy with the free energy, as coordinates in a"space of observables", we slightly modify (the known three) non-holonomic geometrizations from [57, 58, 63] and show that the coeffi...
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One of the most promising applications of quantum networks is entanglement assisted sensing. The field of quantum metrology exploits quantum correlations to improve the precision bound for applications such as precisi...
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A full start-to-end (S2E) software model of a laser system - including oscillator, amplifier, stretcher/compressor, pulse shaper, and non-linear conversion - can be essential in choosing the hardware design and establ...
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