127 research outputs found
Growth, Characterization, and Electrochemical Properties of Doped n-Type KTaO_3 Photoanodes
The effects of compositionally induced changes on the semiconducting properties, optical response, chemical stability, and overall performance of KTaO_3 photoanodes in photoelectrochemical (PEC) cells have been investigated. Single crystals of n-type Ca- and Ba-doped KTaO_3 with carrier concentrations ranging from 0.45 to 11.5×10^(19) cm^(−3) were grown and characterized as photoanodes in basic aqueous electrolyte PEC cells. The PEC properties of the crystals, including the photocurrent, photovoltage, and flatband potential in contact with 8.5 M NaOH(aq) were relatively independent of whether Ca or Ba was used to produce the semiconducting form of KTaO_3. All of the Ca- or Ba-doped KTaO_3 single-crystal photoanodes were chemically stable in the electrolyte and, based on the open-circuit potential and the band-edge positions, were capable of unassisted photochemical H_2 and O_2 evolution from H_2O. The minority-carrier diffusion lengths values were small and comparable to the depletion region width. Photoanodic currents were only observed for photoanode illumination with light above the bandgap (i.e., λ<340 nm). The maximum external quantum yield occurred at λ=255 nm (4.85 eV), and the depletion width plus the minority-carrier diffusion length ranged from 20 to 65 nm for the various KTaO_3-based photoanode materials
Cascaded Multilevel Inverter-Based Asymmetric Static Synchronous Compensator of Reactive Power
The topology of the static synchronous compensator of reactive power for a low-voltage three-phase utility grid capable of asymmetric reactive power compensation in grid phases has been proposed and analysed. It is implemented using separate, independent cascaded H-bridge multilevel inverters for each phase. Every inverter includes two H-bridge cascades. The first cascade operating at grid frequency is implemented using thyristors, and the second one—operating at high frequency is based on the high-speed MOSFET transistors. The investigation shows that the proposed compensator is able to compensate the reactive power in a low-voltage three-phase grid when phases are loaded by highly asymmetrical reactive loads and provides up to three times lower power losses in the compensator as compared with the situation when the compensator is based on the conventional three-level inverters implemented using IGBT transistors.publishedVersio
Intrusion detection systems for smart home IoT devices: experimental comparison study
Smart homes are one of the most promising applications of the emerging
Internet of Things (IoT) technology. With the growing number of IoT related
devices such as smart thermostats, smart fridges, smart speaker, smart light
bulbs and smart locks, smart homes promise to make our lives easier and more
comfortable. However, the increased deployment of such smart devices brings an
increase in potential security risks and home privacy breaches. In order to
overcome such risks, Intrusion Detection Systems are presented as pertinent
tools that can provide network-level protection for smart devices deployed in
home environments. These systems monitor the network activities of the smart
home-connected de-vices and focus on alerting suspicious or malicious activity.
They also can deal with detected abnormal activities by hindering the impostors
in accessing the victim devices. However, the employment of such systems in the
context of a smart home can be challenging due to the devices hardware
limitations, which may restrict their ability to counter the existing and
emerging attack vectors. Therefore, this paper proposes an experimental
comparison between the widely used open-source NIDSs namely Snort, Suricata and
Bro IDS to find the most appropriate one for smart homes in term of detection
accuracy and resources consumption including CP and memory utilization.
Experimental Results show that Suricata is the best performing NIDS for smart
homesComment: 7 pages, 4 figures, 2 table
An improvement of the Berry--Esseen inequality with applications to Poisson and mixed Poisson random sums
By a modification of the method that was applied in (Korolev and Shevtsova,
2009), here the inequalities
and
are proved for the
uniform distance between the standard normal distribution
function and the distribution function of the normalized sum of an
arbitrary number of independent identically distributed random
variables with zero mean, unit variance and finite third absolute moment
. The first of these inequalities sharpens the best known version of
the classical Berry--Esseen inequality since
by virtue of
the condition , and 0.4785 is the best known upper estimate of the
absolute constant in the classical Berry--Esseen inequality. The second
inequality is applied to lowering the upper estimate of the absolute constant
in the analog of the Berry--Esseen inequality for Poisson random sums to 0.3051
which is strictly less than the least possible value of the absolute constant
in the classical Berry--Esseen inequality. As a corollary, the estimates of the
rate of convergence in limit theorems for compound mixed Poisson distributions
are refined.Comment: 33 page
β -delayed neutron emission from Ga 85
Decay of Ga85 was studied by means of β-neutron-γ spectroscopy. A pure beam of Ga85 was produced at the Holifield Radioactive Ion Beam Facility using a resonance ionization laser ion source and a high-resolution electromagnetic separator. The β-delayed neutron emission probability was measured for the first time, yielding 70(5)%. An upper limit of 0.1% for β-delayed two-neutron emission was also experimentally established for the first time. A detailed decay scheme including absolute γ-ray intensities was obtained. Results are compared with theoretical β-delayed emission models
Excited states in As 82 studied in the decay of Ge 82
The excited states of odd-odd As82 are studied in the β decay of Ge82. An isotopically pure beam of Ga83 was produced at the Holifield Radioactive Ion Beam Facility using a resonance ionization laser ion source and high-resolution electromagnetic separation. The atoms of Ge82 are created after β-delayed neutron emission in the decay of Ga83. The number of Ge82 atoms is found by normalization to the 1348-keV γ ray. Detailed analysis of the decay scheme is compared with shell-model calculations with several commonly used fpg shell interactions
βdecays of \u3csup\u3e92\u3c/sup\u3eRb, \u3csup\u3e96gs\u3c/sup\u3eY, and \u3csup\u3e142\u3c/sup\u3eCs measured with the modular total absorption spectrometer and the influence of multiplicity on total absorption spectrometry measurements
Total absorption spectroscopy is a technique that helps obtain reliable β-feeding patterns of complex decays important for nuclear structure and astrophysics modeling as well as decay heat analysis in nuclear reactors. The need for improved measurements of β-feeding patterns from fission decay products has come to the forefront of experiments that use nuclear reactors as a source of antineutrinos. Here we present more detailed results, in particular the β-decay measurements of 96gsY, and demonstrate the impact of the β-delayed γ multiplicity on the overall efficiency of Modular Total Absorption Spectrometer used at Oak Ridge National Laboratory to study the decays of fission products abundant during a nuclear fuel cycle
Experimental study of the β decay of the very neutron-rich nucleus Ge 85
The β-decay properties of the very neutron-rich nucleus Ge85, produced in the proton-induced fission of U238, were studied at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The level scheme of As523385 populated in Ge85βγ decay was reconstructed and compared to shell-model calculations. The investigation of the systematics of low-energy levels in N=52 isotones together with shell-model analysis allowed us to provide an estimate of the low-energy structure of the more exotic N=52 isotone Cu81
β -decay study of Kr 94
β decay of neutron-rich nuclide Kr94 was reinvestigated by means of a high resolution on-line mass separator and β-γ spectroscopy. In total 22 γ-ray transitions were assigned to the decay of Kr94, and a new isomeric state was identified. The new information allows us to build detailed levels systematics in a chain of odd-odd rubidium isotopes and draw conclusions on nuclear structure for some of the observed states. The discussed level structure affects the evolution of β-decay half-lives for neutron-rich selenium, krypton, and strontium isotopes
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