The photodetachment of a homo-nuclear linear tetra-atomic negative molecular ion is studied theoretically for an arbitrary laser polarization.An expression for the total cross section is obtained by using an extended ...The photodetachment of a homo-nuclear linear tetra-atomic negative molecular ion is studied theoretically for an arbitrary laser polarization.An expression for the total cross section is obtained by using an extended version of the two center model,where each center acts as a source of coherent photodetached-electron waves.Strong oscillations on observation plane,placed at a large distance from the ion,are observed.The amplitude of these oscillations is maximum when the laser polarization is parallel to the molecular axis.Furthermore,the amplitude decreases as the angle between the laser polarization and molecular axis increases and consequently vanishes when they are perpendicular to each other.It is also found that if the distance between the adjacent centers is very small or very large,then the ampplitude of oscillations is negligibly small.展开更多
The photodetachment of a hydrogen negative ion (H^(-)) near a hard spherical surface is investigated by using the theoretical imaging method.The surface is oriented in such a fashion that the laser polarization direct...The photodetachment of a hydrogen negative ion (H^(-)) near a hard spherical surface is investigated by using the theoretical imaging method.The surface is oriented in such a fashion that the laser polarization direction is perpendicular to the principal axis of the spherical surface.Analytical expressions are derived for the detachedelectron flux and photodetachment cross section.Strong interference patterns are observed in the detachedelectron flux,while no visible oscillations are found in the photodetachment cross section.展开更多
Photo-detached electron spectra from a hypothetical linear tetra-atomic negative ion is obtained.A plane polarized laser parallel to the axis of the molecular ion is used to knock off the loosely bound electron.The sp...Photo-detached electron spectra from a hypothetical linear tetra-atomic negative ion is obtained.A plane polarized laser parallel to the axis of the molecular ion is used to knock off the loosely bound electron.The spectrum of the detached-electron flux shows strong interference peaks,while the number of peaks increases with the increase in the photon energy.Strong oscillations are also observed in the total photodetachment cross section spectrum.The frequency of the oscillations increases with the increase in the distance between the successive atoms d in the linear chain.These quantum interference effects vanish for very large d or very high photon energy.展开更多
Photodetachment spectra from a linear tetra-atomic negative ion is investigated by treating the detached-electron wave function quantum mechanically.A plane polarized laser light,perpendicular to the axis of the ion,i...Photodetachment spectra from a linear tetra-atomic negative ion is investigated by treating the detached-electron wave function quantum mechanically.A plane polarized laser light,perpendicular to the axis of the ion,is used to detach the electron from the ion.Analytical expressions for the electron flux and total photodetachment cross section are derived.The electron flux on screen shows strong-energy-dependent oscillations with different frequencies.The total cross section of the tetra-atomic negative ion reduces the cross section of mono-atomic,diatomic and triatomic negative ions for high energy photons,while for low energy photons it becomes four times the cross section of mono-atomic negative ions.展开更多
In this paper,we summarise the outcome of a set of experiments aimed at classifying cattle behaviour based on sensor data.Each animal carried sensors generating time series accelerometer data placed on a collar on the...In this paper,we summarise the outcome of a set of experiments aimed at classifying cattle behaviour based on sensor data.Each animal carried sensors generating time series accelerometer data placed on a collar on the neck at the back of the head,on a halter positioned at the side of the head behind the mouth,or on the ear using a tag.The purpose of the study was to determine how sensor data from different placement can classify a range of typical cattle behaviours.Data were collected and animal behaviours(grazing,standing or ruminating)were observed over a common time frame.Statistical features were computed from the sensor data and machine learning algorithms were trained to classify each behaviour.Classification accuracies were computed on separate independent test sets.The analysis based on behaviour classification experiments revealed that different sensor placement can achieve good classification accuracy if the feature space(representing motion patterns)between the training and test animal is similar.The paper will discuss these analyses in detail and can act as a guide for future studies.展开更多
文摘The photodetachment of a homo-nuclear linear tetra-atomic negative molecular ion is studied theoretically for an arbitrary laser polarization.An expression for the total cross section is obtained by using an extended version of the two center model,where each center acts as a source of coherent photodetached-electron waves.Strong oscillations on observation plane,placed at a large distance from the ion,are observed.The amplitude of these oscillations is maximum when the laser polarization is parallel to the molecular axis.Furthermore,the amplitude decreases as the angle between the laser polarization and molecular axis increases and consequently vanishes when they are perpendicular to each other.It is also found that if the distance between the adjacent centers is very small or very large,then the ampplitude of oscillations is negligibly small.
文摘The photodetachment of a hydrogen negative ion (H^(-)) near a hard spherical surface is investigated by using the theoretical imaging method.The surface is oriented in such a fashion that the laser polarization direction is perpendicular to the principal axis of the spherical surface.Analytical expressions are derived for the detachedelectron flux and photodetachment cross section.Strong interference patterns are observed in the detachedelectron flux,while no visible oscillations are found in the photodetachment cross section.
文摘Photo-detached electron spectra from a hypothetical linear tetra-atomic negative ion is obtained.A plane polarized laser parallel to the axis of the molecular ion is used to knock off the loosely bound electron.The spectrum of the detached-electron flux shows strong interference peaks,while the number of peaks increases with the increase in the photon energy.Strong oscillations are also observed in the total photodetachment cross section spectrum.The frequency of the oscillations increases with the increase in the distance between the successive atoms d in the linear chain.These quantum interference effects vanish for very large d or very high photon energy.
文摘Photodetachment spectra from a linear tetra-atomic negative ion is investigated by treating the detached-electron wave function quantum mechanically.A plane polarized laser light,perpendicular to the axis of the ion,is used to detach the electron from the ion.Analytical expressions for the electron flux and total photodetachment cross section are derived.The electron flux on screen shows strong-energy-dependent oscillations with different frequencies.The total cross section of the tetra-atomic negative ion reduces the cross section of mono-atomic,diatomic and triatomic negative ions for high energy photons,while for low energy photons it becomes four times the cross section of mono-atomic negative ions.
文摘In this paper,we summarise the outcome of a set of experiments aimed at classifying cattle behaviour based on sensor data.Each animal carried sensors generating time series accelerometer data placed on a collar on the neck at the back of the head,on a halter positioned at the side of the head behind the mouth,or on the ear using a tag.The purpose of the study was to determine how sensor data from different placement can classify a range of typical cattle behaviours.Data were collected and animal behaviours(grazing,standing or ruminating)were observed over a common time frame.Statistical features were computed from the sensor data and machine learning algorithms were trained to classify each behaviour.Classification accuracies were computed on separate independent test sets.The analysis based on behaviour classification experiments revealed that different sensor placement can achieve good classification accuracy if the feature space(representing motion patterns)between the training and test animal is similar.The paper will discuss these analyses in detail and can act as a guide for future studies.
