Deep Centers Research Articles

Automated face recognition using deep learning technique and center symmetric multivariant local binary pattern

Automated face recognition using deep learning technique and center symmetric multivariant local binary pattern

Proton irradiation Of Ga2O3 Schottky diodes and NiO/Ga2O3 heterojunctions.

p-NiO/n-Ga2O3 heterojunction (HJ) diodes exhibit much larger changes in their properties upon 1.1MeV proton irradiation than Schottky diodes (SDs) prepared on the same material. In p-NiO/Ga2O3 HJ diodes, the narrow region adjacent to the HJ boundary is found to contain a high density of relatively deep centers with levels near EC-0.17eV and a depleted region in the immediate vicinity of the HJ boundary. The series resistance of the HJ diodes is slightly higher than for the Schottky diodes and shows a temperature dependence with activation energy ~ 0.12eV, like the temperature dependence of the NiO film resistivity. Irradiation with 1.1MeV protons leads to a decrease of the hole concentration in the NiO, with a high carrier removal rate of ~ 1.3 × 105cm-1 and a strong compensation of the interfacial region where the concentration of the EC-0.17eV centers decreases with a high rate of ~ 7 × 103cm-1. The combined action of these two effects gives rise to the much stronger increase of the series resistance of the HJ diodes compared to Schottky diodes. The observed differences between the radiation response of the HJs and SDs cannot be credibly attributed to the changes of the density of any of the deep electron and hole traps detected in our experiments.

Huge photosensitivity gain combined with long photocurrent decay times in various polymorphs of Ga2O3: effects of carriers trapping with deep centers

Abstract The materials system of ultra-wide bandgap Ga2O3 has already shown great promise in the field of solar-blind photodetectors with high photoresponsivity, high photoresponsivity gain and low dark current. These promising results have been achieved on Ga2O3 films of different polymorphs and by different methods, often not with particularly high crystalline quality. In fact, it would often seem the case that the lower the crystalline quality of the films, the higher the photosensitivity and its gain. This, however, is in most cases accompanied by unusually long photocurrent build-up and decay times. We show that the experimental results can be explained by models in which the high photosensitivity gain is related to the effects of holes being trapped by deep states that, in Schottky diodes, results in the decrease of the Schottky barrier height with consequent increase of electron current, and in Metal-Semiconductor-Metal (MSM) structures additionally gives rise to the usual gain increase due to the increased concentration and lifetime of electrons. We present and discuss the models describing the effects in Ga2O3 Schottky diodes, MSM structures, unipolar and bipolar heterojunctions and propose possible candidates for the role of the hole traps in different Ga2O3 polymorphs. We also discuss the existing results for the photocurrent build-up and decay times and offer possible explainations of the observed temperature dependences of the characteristic times where such data are present.

Geoelectric heterogeneities of the Pre-Dobrudga Trough a zone of hydrocarbon manifestations

For the first time, a geological and geoelectrical interpretation of the three-dimensional model of the Earth’s crust and upper mantle was carried out for the Pre-Dobrudga Trough and adjacent areas. It was based on observations of the Earth’s low-frequency electromagnetic field conducted in 2009―2012 by the National Academy of Sciences of Ukraine. The material confidently indicates that hydrocarbon occurrences are confined to the detected anomalies of high electrical conductivity. These are characterized by subvertical channels (from the surface to 10 km deep) galvanically connected with sediments or sub-vertical contact zones of different resistivity observed not only in the Earth’s crust (10―40 km) but also at crust-mantle depths (40―60 km) and in the upper mantle (110―160 km).The channels may determine the flow of ultra-deep fluids. The geoelectric criteria included maximum thickness of the sedimentary stratum, subvertical rise of electrical conductivity anomalies from the crust-mantle depths or column to the entire thickness of the Earth’s crust, subvertical boundaries of heterogeneities (contacts of different resistivity) in the consolidated Earth’s crust and upper mantle,presence of a highly conductive asthenospheric layer. We identified a significant number of local areas that can be considered promising for hydrocarbon occurrence. The majority of them spatially coincided with the already well-known oil and gas fields ― Skhidnosaratske and Zhovtoyarske, with the explored oil and gas prospective areas (Izmailska, Kyslytska, Prymorska, Shyrokivska), and with those that correspond to the areas of special permits for industrial exploration. However, the newly discovered areas that meet most of the geoelectric criteria, but for which no no information on oil and gas content is publicly available, clearly require additional geological and geophysical studies. It has been shown that zones of high electrical conductivity caused by the presence of deep fluids should be considered as deep centers of hydrocarbon generation and ways of their migration to the upper horizons of the Earth’s crust.

CNN-MLP-Based Configurable Robotic Arm for Smart Agriculture

Amidst escalating global populations and dwindling arable lands, enhancing agricultural productivity and sustainability is imperative. Addressing the inefficiencies of traditional agriculture, which struggles to meet the demands of large-scale production, this paper introduces a highly configurable smart agricultural robotic arm system (CARA), engineered using convolutional neural networks and multilayer perceptron. CARA integrates a highly configurable robotic arm, an image acquisition module, and a deep processing center, embodying the convergence of advanced robotics and artificial intelligence to facilitate precise and efficient agricultural tasks including harvesting, pesticide application, and crop inspection. Rigorous experimental validations confirm that the system significantly enhances operational efficiency, adapts seamlessly to diverse agricultural contexts, and bolsters the precision and sustainability of farming practices. This study not only underscores the vital role of intelligent automation in modern agriculture but also sets a precedent for future agricultural innovations.

Preparation of porous composite coatings to suppress surface charge movement and reduce electrical resistivity

In this work, Cr2O3/TiO2 composite coatings were prepared on α-Al2O3 insulating ceramic matrix surface by screen printing and solid phase sintering methods to yield an average film thickness of about 14.10 μm. Scanning electron microscopy (SEM) revealed changes in the pore structures of the coatings at different TiO2 contents. The atomic force microscopy (AFM) analysis of the coating surface roughness suggested a TiO2 content of 0.025 mol to yield the best surface roughness and pore structure of the coating. The calculation showed an increase in the energy level of the deep trap center on the surface from 1.506 eV to 1.547 eV, reaching a maximum. The surface resistivity of insulating ceramics decreased from 1016 Ω to 1012 Ω. The formation of deep surface traps and the decrease in surface resistivity promoted charge dispersion and suppressed the formation of flashover channels, effectively improving the surface flashover voltage of the ceramics.

Major Complications of Deep Venous Stenting.

Deep venous stent placement has developed into a primary treatment modality for venous obstruction in recent decades. Reported rates of complications are low in the literature and are based mainly on case reports and single-centre cohorts. Interventionalists performing these procedures must be aware of the occurrence of complications associated with stent placement to counsel patients adequately and promote avoidance through optimal procedural approach. This study aims to determine the incidence of serious complications associated with iliocaval and iliofemoral stent placement in a cohort of patients from 3 major tertiary deep venous referral centres. Data were collated from January 2014 to September 2023. The following major complications were included in the analysis: death, major bleeding requiring transfusion, massive pulmonary embolism, any complication which required endovascular or open surgical intervention, vessel rupture, acute kidney injury requiring dialysis, stent crushing, fracture, migration, involution or erosion. One thousand eight hundred fourteen (1814) patients were treated for acute or chronic deep venous pathology during the 9-year study period. Sixty-one patients (3.3%) experienced a major stent-related complication. The most frequently reported complication was stent crushing (n = 18, 29.5%), followed by stent fracture (n = 10, 16.4%) and erosion of the stent through the vessel wall (n = 8, 13.1%). Death was a rare event (0.2%). Deep venous stent placement is a safe procedure with low rates of major complications. It is incumbent upon operators to be aware of the risks associated with these procedures, however, rare, so that they may obtain fully informed consent from patients.

Beneficial role of manganese dioxide for reducing surface resistivity to increase surface flashover voltage of vacuum insulating ceramics

Electric vacuum insulated devices generate surface flashover and breakdown under instantaneous high voltage. Flashover voltage can be increased through coating without changing the structure of the ceramic device. Herein, multiphase coatings with different manganese dioxide contents are prepared on α-Al2O3 insulating ceramic surface by screen printing and solid-state sintering methods to yield an average film thickness of about 12.38 μm with good bonding strength. X-ray diffraction shows that the crystal phases of the coating are (Al0.9Cr0.1)2O3 and MnAl2O4. Scanning electron micrographs and atomic force microscopy reveal that greater surface height difference and deeper surface depth are more conducive to increasing the surface roughness and the formation of "pores", and decreasing the surface potential decay rate. When MnO2 content is 0.0069 mol, the deep trap center energy level on the material surface reaches its maximum, increasing from 1.506 eV to 1.550 eV, and the surface resistivity of ceramics decreases from 1016 Ω to 1013 Ω. The formation of deep trap centers on the surface makes it difficult for surface charges to detach, which reduces the charge mobility and surface potential decay rate, and leads to decrease in surface resistivity and increase in surface flashover voltage.

Factors Associated with the Opinion on Self-Care of Elderly in Southernmost Provinces, Thailand

Background and Aims: Self-care is crucial for the elderly since it allows everyone to have a healthy life, boost immunity, prevent sickness, care for themselves when unwell, and continue to perform everyday duties in their own homes. This study aimed to investigate the factors influencing the elderly's opinions on self-care in the southernmost provinces of Thailand. Methodology: This quantitative study used data collected by the Deep South Coordination Center from 271 elderly people in Pattani. The independent variable included demographic factors and health conditions. The outcome variable was a 4-point rating scale opinion on the self-care of the elderly. Descriptive statistics were employed to illustrate the sample's characteristics. Factor analysis was used to reduce the number of outcome variables. Multiple linear regression was used to examine the relationship between the outcome variables and the independent variables. Results: Eighteen outcome variables were categorized into three factors consisting of positive self-management, health preparation, and doing things for great pleasure. Elderly people who could walk with their spouse or family were more likely to have positive self-management and health preparation than those who lived alone or were separated and could not walk. Elderly people who did not engage in health-risk activities and could use public transportation independently were more likely to enjoy themselves than those who could not. Conclusion: The findings might improve the quality of self-care among the elderly to live better in their current societal situation. This can encourage care healthcare providers to promote daily living practices among the elderly.

DFT study of the role and possible contribution of defects to lithium metasilicate [formula omitted] luminescence

Lithium metasilicate (Li2SiO3) has recently been shown to display outstanding stimulated luminescence properties, which are governed by defects and/or impurities. Here, the possible contribution and character of native point and complex defects to stimulated luminescence of lithium metasilicate have been investigated employing calculations based on the density functional theory (DFT). Under high concentrations of acceptor defects, isolated lithium interstitials were found to be the defects with the lowest formation energy (0.41 eV) but it is shown that they cannot contribute to luminescence. On the other hand, Oi−2 are the most favorable and stable defects under high concentrations of donor defects. F-centers and oxygen peroxides were identified as first- and second-order processes of point defects, which would explain experimental observations in the literature. Bridging oxygen vacancies were shown to introduce shallow electron traps able to trap up to four electrons. On the contrary, non-bridging oxygen vacancies lead to the formation of deep color centers with the capability of trapping up to two carriers/center, which could be the final state for the radiative process of luminescence. These results provide guidance for the interpretation of experimental measurements of luminescence.

Deep Learning and Face Recognition: Face Recognition Approach Based on the DS-CDCN Algorithm

To enhance the performance and reliability of the face recognition algorithm that is based on deep learning technology, this study utilizes a density-based noise-applied spatial clustering algorithm to cluster a large-scale face image dataset, resulting in a self-constructed dataset. A deep separable center differential convolutional network algorithm is utilized for face recognition. The impact of convolutional parameters on the algorithm’s performance is verified through experiments with ablated convolutional parameters. The study found that the density-based noise-applied spatial clustering algorithm resulted in time savings of 43.66% and 51.22% compared to the K-means clustering algorithm and the hierarchical clustering algorithm, respectively, when analyzing 8000 images. Additionally, the depth-separable center difference convolutional network algorithm had a lower average classification error rate compared to the other two algorithms, with reductions of 2.49% and 17.01%, respectively. The depth-separable center difference convolutional network technique is an advanced method for identifying the faces of people of different races, according to the experimental investigation. It can provide efficient and accurate services for the face recognition needs of various races.

Enhancing deep orebody prediction and localization through the revelation of geochemical primary halo patterns in drill holes

Geochemical primary halos play a crucial role in mineral exploration as they provide valuable insights into the dispersion of ore materials, identification of concealed deposits, and determination of ore deposit dimensions. The Naruo mining area in the Duolong mineral district, northern Tibet, China well-known for its worldclass porphyry-epithermal Cu–Au deposits is currently chosen as the study area. We employ statistical and nonlinear methods to analyze geochemical data from drill holes. Specifically, R-type cluster analysis is utilized to evaluate element affinity and concentration index, while an improved Grigorian zoning index is employed to delineate the vertical zoning sequence of the primary halo. These methodologies significantly enhance our understanding of element enrichment within geological contexts and greatly contribute to mineral resource evaluation. Based on these results, we have constructed a vertical zonation index model of denudation coefficient tailored to the geological characteristics of mineralization within the study area. This model effectively represents the vertical variation of the ore body. Our findings reveal a decrease in this zoning index towards the central region of deep ore bodies which correlates with deep granodiorite porphyry occurrences. Furthermore, we observe increasing concentrations of Cu, Ag, and Au with depth in specific sections of drill holes indicating promising exploration potential. Supplementary short-wave infrared data suggests the presence of a deep hydrothermal center in drill hole RNZK2404 which tentatively infers concealed porphyry bodies. Notably, the reversal observed at 4200 m on RNZK2404's zoning index hints at a possible hidden ore body at great depths. Finally, three-dimensional visualization techniques effectively illustrate spatial patterns for elements thereby paving way for future endeavors in mineral exploration.

Photovoltaic Rotation and Transportation of a Fragile Fluorescent Microrod Toward Assembling a Tunable Light-Source System.

Continuous rotation of a fragile, photosensitive microrod in a safe, flexible way remains challenging in spite of its importance to microelectro-mechanical systems. We propose a photovoltaic strategy to continuously rotate a fragile, fluorescent microrod on a LiNbO3/Fe (LN/Fe) substrate using a continuous wave visible (473 nm) laser beam with an ultralow power (few tens of μW) and a simple structure (Gaussian profile). This strategy does not require the laser spot to cover the entire microrod nor does it result in a sharp temperature rise on the microrod. Both experiments and simulation reveal that the strongest photovoltaic field generated beside the laser spot firmly traps one corner of the microrod and the axisymmetric photovoltaic field exerts an electrostatic torque on the microrod driving it to rotate continuously around the laser spot. The dependence of the rotation rate on the laser power indicates contributions from both deep and shallow photovoltaic centers. This rotation mode, combined with the transportation mode, enables the controllable movement of an individual microrod along any complex trajectory with any specific orientation. The tuning of the end-emitting spectrum and the photothermal cutting of the fluorescent microrod are also realized by properly configuring the laser illumination. By taking a microrod as the emitter and a polystyrene microsphere as the focusing lens, we demonstrate the photovoltaic assembly of a microscale light-source system with both spectrum and divergence-angle tunabilities, which are realized by adjusting the photoexcitation position along the microrod and the geometry relationship in the system, respectively.

Contactless spectroscopy of photoactive centres in sapphire and nitride layered structures

Spectroscopy of photo-active centres in wide bandgap optical materials with absorption and emission bands in the range close to vacuum ultraviolet spectrum is complicated. In this work, the pulsed photo-ionization (PPI) transients, electron spin resonance (ESR) and proton induced luminescence spectroscopy techniques have been combined to evaluate the origin and parameters of deep centres in crystalline sapphire substrates. Additionally, the layered structures with MOCVD grown thin top layers of GaN, AlGaN and AlN on sapphire substrates were examined in order to clarify origin of emission bands related to the epilayers and sapphire. The sapphire assigned emission bands have been ascribed to the F+ centres, characterized by photo-activation energy of 4.8 eV. Prevailing of F+ centres has been confirmed by ESR spectroscopy results. The covering nitride layers of AlN, AlGaN and GaN led to appearance of the additional PPI spectral peaks ascribed to recombination on the interface between epitaxial material and sapphire substrate.

Origin and Recovery of Negative VTH Shift on 4H–SiC MOS Capacitors: An Analysis Based on Inverse Laplace Transform and Temperature-Dependent Measurements

SiC power MOSFETs are reported to suffer from both positive and negative threshold voltage shifts. Positive shift is well understood in the literature and attributed to electron trapping in near interface oxide traps (NIOTs). Negative shift is explained by hole generation and trapping in the oxide via impact ionization favored by the strong oxide field. However, studies on negative shift are still ongoing, and the origin and nature of the process are not fully understood. This study advances the comprehension of negative threshold voltage shift by investigating MOS capacitors subject to positive bias stress.We demonstrate that: a) a significant negative threshold shift is observed when the electric field is greater than 7.5 MV/cm; b) the detected shift is not recoverable at zero bias. Recovery can be obtained only by applying a positive gate voltage indicating a field-driven detrapping process. c) Trap-state mapping measurements were carried out to extract the activation energy of the detrapping processes, and a weak thermal activation was observed.Results collected within this paper indicate that holes are trapped at deep centers, and thermal detrapping is not possible. Hole release is only possible when a high field is applied to the insulator, possibly due to the recombination between leaking electrons and trapped holes.

Native point defects in HgCdTe infrared detector material: Identifying deep centers from first principles

We investigate the native point defects in the long-wavelength infrared (LWIR) detector material Hg0.75Cd0.25Te using a dielectric-dependent hybrid density functional combined with spin–orbit coupling. Characterizing these point defects is essential as they are responsible for intrinsic doping and nonradiative recombination centers in the detector material. The dielectric-dependent hybrid functional allows for an accurate description of the bandgap (Eg) for Hg1−xCdxTe (MCT) over the entire compositional range, a level of accuracy challenging with standard hybrid functionals. Our comprehensive examination of the native point defects confirms that cation vacancies VHg(Cd) are the primary sources of p-type conductivity in the LWIR material given their low defect formation energies and the presence of a shallow acceptor level (−/0) near the valence-band maximum. In addition to the shallow acceptor level, the cation vacancies exhibit a deep charge transition level (2−/−) situated near the midgap, characteristic of nonradiative recombination centers. Our results indicate that Hg interstitial could also be a deep center in the LWIR MCT through a metastable configuration under the Hg-rich growth conditions. While an isolated Te antisite does not show deep levels, the formation of VHg–TeHg defect complex introduces a deep acceptor level within the bandgap.

High-performance computing: Transitioning from Instruction-Level Parallelism to heterogeneous hybrid architectures

This paper delves into the shift from Instruction-Level Parallelism (ILP) to Heterogeneous Hybrid Parallel Computing in the quest for optimized performance processing. It sheds light on the constraints of ILP, emphasizing how these shortcomings have catalyzed a move toward the more adaptable and proficient framework of heterogeneous hybrid computing. This transformation's advantages are explored across diverse applications, notably in deep learning, cloud computing, data centers, and mobile SoCs. Additionally, the study underscores emerging architectures and innovations of this era, including many-core processors, FPGA-driven accelerators, and an assortment of software tools and libraries. While heterogeneous hybrid computing offers a promising horizon, it isn't without challenges. This paper brings to the fore issues like restricted adaptability, steep development costs, software compatibility hurdles, the absence of a standardized programming model, and vendor reliance. Through this in-depth exploration, our aim is to present a holistic snapshot of the present and potential future of high-performance processing.

Problems in organizing neurosurgical care for patients with Parkinson's disease in the Russian Federation

Currently, there are some problems in the Russian Federation complicating development of neurosurgical care for patients with Parkinson's disease (PD). In 2022, neurologists - movement disorders specialists were surveyed to analyze situation with PD pharmacological treatment and referral of patients for surgical treatment in Russian constituent entities. Data on neurosurgical treatment of PD were obtained by collecting information on the surgical activity of medical institutions in the Russian Federation. Most hospitals involved in PD treatment took part in this study. The state of neurosurgical care for patients with PD is analyzed and possible ways to improve the quality of treatment are discussed. Over the past 20 years, a system of neurosurgical care for patients with PD has been formed in 14 centers in the Russian Federation (2022). Obstacles to its further development can be divided into 3 categories: problems of patient selection and routing, complexity of organization and financing surgeries, and imperfect postoperative patient management. Ways to overcome these obstacles imply expanding the network of centers for extrapyramidal diseases, development of domestic neurostimulation systems, improving the distribution of quotas taking into account the capabilities of hospitals, specialized training of neurologists for extrapyramidal centers and neurosurgeons for deep brain stimulation centers, adequate financing and systematization of postoperative management of patients with PD.

Carrier recombination in highly Al doped 4H-SiC: dependence on the injection conditions

We investigate carrier recombination mechanisms in heavily aluminum (Al) doped p-type 4H-SiC, a material crucial for power devices. The recombination mechanisms in Al-doped p-type 4H-SiC have remained unclear, with reports suggesting various possibilities. To gain insights, we employ photoluminescence (PL) measurements, particularly time-resolved PL (TR-PL), as they are well-suited for studying carrier lifetimes in heavily Al-doped p-type 4H-SiC. We examine the temperature and excitation intensity dependencies of TR-PL and PL spectra and discuss the underlying recombination mechanisms. We observe that the dominant recombination mechanism varies with injection conditions for the samples with Al concentration less than 1019 cm−3. Under low injection conditions, recombination via the Al acceptor level appears dominant, exhibiting weak temperature dependence. However, under high injection conditions, Shockley–Read–Hall recombination takes precedence, leading to shorter carrier lifetimes with increasing temperature. This temperature dependence implies that presences of the deep recombination centers with the small capture barrier for holes.

Luminescent properties of Cd(x)Zn(1-x)S nanocrystals formed in the matrix of a Langmuir–Blodgett film

At a temperature of 80–300 K, the photoluminescence of Cd(x)Zn(1-x)S nanocrystals (x = 0.2 and 0.5) formed in a Langmuir–Blodgett film was studied. Two peaks can be distinguished in the PL spectra: (i) a low-energy peak, which is portable and changes significantly with increasing zinc content in nanocrystals and temperature, and (ii) a high-energy peak, the position of which weakly depends on temperature and nanocrystal content. It was found that the high-energy peak is most pronounced at elevated temperatures (>290 K). Experimental data are performed by recombination through levels of deep centers associated with the intrinsic defects and behenic acid molecules on the surface of nanocrystals.