330 research outputs found
Collective Coordinate Approach to the Dynamics of Various Soliton-Obstruction Systems
Various soliton-obstruction systems have been studied from analytical
perspective. We have used collective coordinate to approach the dynamics of
solitons as they meet a potential obstruction in a form of square barriers and
holes for three models in (1+1) dimensions, namely: model,
deformed Sine-Gordon model, and a model that give rise to Q-ball solution. We
have shown that our approximated field solution is valid enough to describe the
behaviour of solitons scattering off a potential obstruction.Comment: 26 pages, 18 figure
Behaviour of Soft Clayey Soil Improved by Fly Ash and Geogrid under Cyclic Loading
The effect of Cyclic loading on the foundation behaviour of many engineering structures presents more important and related to many problems in geotechnical engineering, Especially when construction on soft ground area which represent one of the major concerns in geotechnical engineering. This paper is conducted to investigate the influence of using several improving techniques as (fly ash, Geo-grid, fly ash and Geo-grid) on the behavior of soft clayey soil subjected to cyclic loading. A total of twenty four models have been tested which consists of a wide domain of boundary conditions, such as untreated model, Geo-grid reinforced models, fly ash treated models and models treated with fly ash incorporated with Geo-grid were conducted by varying parameters such as, footing elevations, test velocity and number of geogrid layers. The analysis demonstrates that the settlement behaviour of footing resting on treated models with fly ash and two Geo-grid layers perform better than other improving techniques. Also observed there was an increase in settlement, which corresponds to the increase in test velocity from 6 to 9 mm/sec. Furthermore, it was conducted that the more depth of footing the soil settlement decreases. In general, when other factors remaining constant, the bearing capacity of soil goes on increasing when the depth increased
Emisija kratkovalnog zračenja tijekom udara iona o čvrstu površinu
The possibility of short-wave photon emission during surface scattering of positive ions is investigated by selection of the type of charge-exchange process (one- or two-electron processes), through the calculation of the neutralization probabilities and the charge-transfer cross sections. These probabilities are calculated statically as a function of distance between the incident ion and the surface, and dynamically as a function of the ion velocity. The model is applied to real systems such as He+/semiconductor (silicon and germanium), taking into account the difference in the physical constants of the two systems. We found that emitted photons have short wavelengths, lying in the ultraviolet range of the electromagnetic spectrum of the helium emission spectrum.Istražujemo mogućnost emisije kratkovalnih fotona tijekom udara iona o čvrstu površinu odabirom procesa izmjene naboja (jedno i dvoelektronski procesi) i računanjem vjerojatnosti neutralizacije i udarnog presjeka za prijenos naboja. Te vjerojatnosti računamo statički kao funkcije udaljenosti upadnog iona i površine, i dinamički kao funkcije brzine iona. Model primjenjujemo stvarnim sustavima kao što su poluvodiči silicij i germanij, uzimajući u obzir razlike fizičkih svojstava dvaju sustava. Nalazimo da fotoni imaju kratke valne duljine, u području elektromagnetskog spektra helija
The Electron Transport Through Strongly Coupled Double Quantum Dots : Effect of Spin Exchange Interaction
We introduce model calculation for the electron transport through a system consists of two serially coupled quantum dots, embedded between two nonmagnetic leads (source and drain). In our treatment, the time independent Anderson-Newns Hamiltonian model is considered as a basis to study the system dynamics and then to derive spin-dependent analytical formula to calculate the occupation numbers of the quantum dots energy levels, the corresponding quantum dots energy levels and the molecular virtual energy levels, as a function of bias voltage. These relations are solved self-consistently, which are all employed to calculate the tunneling current considering the strong coupling regime. The differential conductance is calculated numerically by using finite differences method. And as the efficiency of electron transport through coupled quantum dots depends on the system parameters, the effective exchange energy is highlighted and studied in details and the role of this parameter in the tunneling current and the differential conductance calculations is presented. Our treatment is utilized to study the following The role of the spin exchange interaction in determining the type of interaction (if it is attractive or repulsive) between the quantum dots...
NcPred for accurate nuclear protein prediction using n-mer statistics with various classification algorithms
Prediction of nuclear proteins is one of the major challenges in genome annotation. A method, NcPred is described, for predicting nuclear proteins with higher accuracy exploiting n-mer statistics with different classification algorithms namely Alternating Decision (AD) Tree, Best First (BF) Tree, Random Tree and Adaptive (Ada) Boost. On BaCello dataset [1], NcPred improves about 20% accuracy with Random Tree and about 10% sensitivity with Ada Boost for Animal proteins compared to existing techniques. It also increases the accuracy of Fungal protein prediction by 20% and recall by 4% with AD Tree. In case of Human protein, the accuracy is improved by about 25% and sensitivity about 10% with BF Tree. Performance analysis of NcPred clearly demonstrates its suitability over the contemporary in-silico nuclear protein classification research
Time calibration studies for the Timepix3 hybrid pixel detector in electron microscopy
Direct electron detection is currently revolutionizing many fields of
electron microscopy due to its lower noise, its reduced point-spread function,
and its increased quantum efficiency. More specifically to this work, Timepix3
is a hybrid-pixel direct electron detector capable of outputting temporal
information of individual hits in its pixel array. Its architecture results in
a data-driven detector, also called event-based, in which individual hits
trigger the data off the chip for readout as fast as possible. The presence of
a pixel threshold value results in an almost readout-noise-free detector while
also defining the hit time of arrival and the time the signal stays over the
pixel threshold. In this work, we have performed various experiments to
calibrate and correct the Timepix3 temporal information, specifically in the
context of electron microscopy. These include the energy calibration, and the
time-walk and pixel delay corrections, reaching an average temporal resolution
throughout the entire pixel matrix of ns. Additionally, we have
also studied cosmic rays tracks to characterize the charge dynamics along the
volume of the sensor layer, allowing us to estimate the limits of the
detector's temporal response depending on different bias voltages, sensor
thickness, and the electron beam ionization volume. We have estimated the
uncertainty due to the ionization volume ranging from about 0.8 ns for 60 keV
electrons to 8.8 ns for 300 keV electrons
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