Position Dependence Research Articles

Compact MMW-band Planar Diffraction Type Antennas for Various Applications

The principles of formation of antennas of diffraction radiation with flat surface in the millimeter wave radio band are considered. Such kinds of antennas are based on the effect of the conversion of volumetric electromagnetic waves into surface waves of a dielectric waveguide in an open electrodynamic structure. A brief description of the theoretical basis for the calculations and examples of the technical implementation of flat (2D) antennas of diffraction radiation in the W-band and Ka-band are presented; their parameters and areas of possible use are discussed. In the <i>E</i>-plane angle-to-frequency dependence of beam position is realized with coefficient near 0,9/1% of frequency change. That makes it possible effective control of beam position in space (beam scanning along 1, or even along 2 axes). There was estimated that total active loss in such kind antennas is related to dielectric losses in the material of planar dielectric waveguide and to active losses at the elements of internal waveguide transitions in the ratio near (2: 1). Losses of first kind may be reduced due to implementation of novel dielectric materials providing the smallest dielectric loss (near as for the PTFE material) and appropriate mechanical rigidity at the same time. Active losses of the second kind may be reduced due to implementation of transitions on the base of super-size waveguides.

Поведение доноров лития в объемных монокристаллических моноизотопных сплавах -=SUP=-28-=/SUP=-Si-=SUB=-1-x-=/SUB=--=SUP=-72-=/SUP=-Ge-=SUB=-x-=/SUB=-

We studied the behavior of lithium donors in bulk single-crystal single-crystal alloys Si1-xGex, (x=0.0039-0.05), enriched in spinless isotopes 28Si (99.998%) and 72Ge (99.984%) by electron paramagnetic resonance (EPR). The fine structure of the spectrum of a donor electron localized on lithium (T=3.5–30 K) was studied under the assumption that, when spinless isotopes (28Si isoGe, iso = 70, 72, 74, 76) are enriched in Si1-xGex alloys, it is possible to achieve in higher resolution in the EPR spectra as was observed in silicon. Studies have shown that despite the irregular arrangement of germanium atoms in the lattice of a SiGe, the local distortions they create and the broadening of the EPR lines of donor electrons due to random deformations in isotopically pure 28Si1-х72Geх single crystals at x=0.39; 1.2; 2.9 %, narrower lines of the ESR spectra of lithium were observed in comparison with similar crystals with a natural composition of silicon and germanium isotopes, which made it possible, as in silicon, to study for the first time the angular dependences of the line positions in the ESR spectra of lithium in Si1-xGex for various x.

Dynamics of 1-D Electron Motion under a Periodic Electric Field with Radiation Reaction Effect

We consider the 1-D motion of an electron under a periodic force and take into account the effect of radiation reaction dissipation force on its motion, using the formulation of novel radiation reaction force as a function of the external force expression. Two cases are considered: a simple sinusoidal time depending force, and sinusoidal electromagnetic force with position and time dependence. The purpose of the study of these cases is to bring about a way to find an experimental study to determine the validity of this novel approach for the radiation reaction force. We found that the difference of the normalized (with respect the speed of light) velocities, with and without radiation reaction, is quite small between 10-31 to 10-14 for intensities on the electric field of 10-8 to 1 Dynes/ues, which may represent some concern to measure experimentally.

Computational Structure-Activity Relationship (SAR) of Berberine Analogs in Double-Stranded and G-Quadruplex DNA Binding Reveals Both Position and Target Dependence

Berberine, a natural product alkaloid, and its analogs have a wide range of medicinal properties, including antibacterial and anticancer effects. Previous studies showed that berberine and its analogs intercalate into DNA, thereby inhibiting DNA replication. Berberine has also been studied as a photosensitizer and was shown to generate reactive singlet oxygen in situ, and this has applications in photodynamic therapy. Various groups have synthesized berberine analogs that have comparable or improved biological activity; however, an exhaustive structure-activity relationship of the free energy of binding of berberine analogs with substitution at C-8, C-12, and C-13 to DNA have not been previously reported. High throughput virtual screening (HTVS) allows for efficient analysis of compound libraries to identify lead compounds as possible pharmaceutical agents. Here, we employed HTVS towards a library of alkyl or aryl berberine analogs on C-8, C-12, and C-13 to probe binding to double-stranded and G-quadruplex DNA. Predicted free energies of binding to double-stranded DNA and G-quadruplex DNA were generated via molecular docking. The excited state electronic structure calculations were conducted via time-dependent density functional theory to probe the potential photosensitizing activity of each compound, and the potential G-quadruplex stabilizing abilities of key berberine analogs were probed through molecular dynamics simulations on a 4.0 nanosecond timescale. We determined that the nature of the substituent, the position of the substituent, and the nucleic acid target affect the free energy of binding of berberine analogs to DNA and G-quadruplex DNA, however berberine analogs did not result in net stabilization of G-quadruplex DNA.

Intelligent Diagnosis for Railway Wheel Flat Using Frequency-Domain Gramian Angular Field and Transfer Learning Network

The intelligent diagnosis of wheel flat based on vibration image classification is a promising research subject for performance maintenance of railway vehicles. However, the image representation method of vibration signal and classification network construction under small samples have become two obstacles to intelligent diagnosis of wheel flat. This paper presents a novel frequency-domain Gramian angular field (FDGAF) algorithm to encode the vibration signal of wheel flat to featured images. Furthermore, a modified transfer learning network is introduced to classify these featured images under small samples without any involvement of prior knowledge. The proposed FDGAF can calculate the Gramian angular matrix of axle box acceleration signal in frequency domain and assign frequency position dependence to the featured images to preserve original characteristic information. Then, these featured images can be intelligent classified by a transfer learning network under the condition of 30 sample without require of prior knowledge. To verify the efficiency of this proposed method, 12 cases of artificial wheel flats are processed on a scaled railway test rig, and their axle box acceleration signals are collected to obtain visual diagnosis results. The verfication proves that FDGAF is able to obtain accurate diagnostic results with high separability, for separability indexes of FDGAF reaches 10.8, 8.7, 14.9, and 5.8. We anticipate that this method will find use in the performance maintenance of railway vehicles and the improvement of industrial condition monitoring.

Ignition position dependence and skin absorption characteristics of light radiated from moxa needle

Ignition position dependence and skin absorption characteristics of light radiated from moxa needle

Positional dependence of particles and cells in microfluidic electrical impedance flow cytometry: origin, challenges and opportunities.

Microfluidic electrical impedance flow cytometry is now a well-known and established method for single-cell analysis. Given the richness of the information provided by impedance measurements, this non-invasive and label-free approach can be used in a wide field of applications ranging from simple cell counting to disease diagnostics. One of its major limitations is the variation of the impedance signal with the position of the cell in the sensing area. Indeed, identical particles traveling along different trajectories do not result in the same data. The positional dependence can be considered as a challenge for the accuracy of microfluidic impedance cytometers. On the other hand, it has recently been regarded by several groups as an opportunity to estimate the position of particles in the microchannel and thus take a further step in the logic of integrating sensors in so-called "Lab-on-a-chip" devices. This review provides a comprehensive overview of the physical grounds of the positional dependence of impedance measurements. Then, both the developed strategies to reduce position influence in impedance-based assays and the recent reported technologies exploiting that dependence for the integration of position detection in microfluidic devices are reviewed.

Data enhanced Hammett-equation: reaction barriers in chemical space.

It is intriguing how the Hammett equation enables control of chemical reactivity throughout chemical space by separating the effect of substituents from chemical process variables, such as reaction mechanism, solvent, or temperature. We generalize Hammett's original approach to predict potential energies of activation in non aromatic molecular scaffolds with multiple substituents. We use global regression to optimize Hammett parameters ρ and σ in two experimental datasets (rate constants for benzylbromides reacting with thiols and ammonium salt decomposition), as well as in a synthetic dataset consisting of computational activation energies of ∼2400 SN2 reactions, with various nucleophiles and leaving groups (–H, –F, –Cl, –Br) and functional groups (–H, –NO2, –CN, –NH3, –CH3). Individual substituents contribute additively to molecular σ with a unique regression term, which quantifies the inductive effect. The position dependence of substituents can be modeled by a distance decaying factor for SN2. Use of the Hammett equation as a base-line model for Δ-machine learning models of the activation energy in chemical space results in substantially improved learning curves reaching low prediction errors for small training sets.

ФЛУОРЕСЦЕНТНІ ХАРАКТЕРИСТИКИ РОЗЧИНІВ ФЛУОРЕСЦЕЇНУ ТА ЕОЗИНУ Н У ВОДНО-МІЦЕЛЯРНИХ СЕРЕДОВИЩАХ ПАР

The effect of cationic, anionic and nonionic surfactants on the fluorescence properties of fluorescein and eosin Y aqueous solutions has been investigated. It has been found that sodium dodecyl sulfate does not affect the position of the maximum wavelengths of solutions of fluorescein and eosin Y in the study of the effect of an anionic surfactant on the fluorescence emission intensity of dyes. The intensity of the signal of the dye solutions when changing the concentration of anionic surfactant changes little. As the concentration of non-ionic surfactant increases, the fluorescence emission intensity of the fluorescein solutions decreases. In contrast, with increasing concentration of Triton X-100, there is an increase in the signal intensity of solutions of more hydrophobic eosin Y with subsequent access to the "plateau" at СТХ-100≥5.1·10–2 mol/L. The position of the maxima fluorescence emission wavelengths for the fluorescein solutions in the 0-1.0·10–5 mol/L range of concentrations of cationic surfactant cetylpyridinium chloride remain unchanged. The position of the maxima shifts to the long-wavelength region of the spectrum at higher concentrations of CPC. The nature of the position dependence of the fluorescence emission maxima of eosin Y solutions in the presence of cationic surfactants is similar. The effect of fluorescence quenching has also been shown in the study of the influence of organic substances of cationic nature on the signal intensity of fluorescein solutions. It has been shown that the concentration dependence is linear in the (0.1–4.0)·10–1 mol/L range of isoniazid molecule concentrations. The data obtained can be implemented in the development of conditions and methods for the determination of pharmacologically active substances of cationic nature by reaction with fluorescein in medicines.

An aging theory‐based mathematic model for estimating the wax content of wax deposits using the Fick's second law

AbstractIn this study, a mathematic model is proposed for estimating the wax content of wax deposits. The proposed model was built based on the diffusion of wax molecules and counter‐diffusion of oil molecules and described using the Fick's second law, allowing for the stacking fraction and orientational order of precipitated wax crystals and the tortuosity of diffusion path of de‐waxed oil molecules during the counter‐diffusion. The calculated results were verified by comparing with the flow‐loop wax deposition experimental results. Dependence of radial position, deposition duration, bulk temperature, and wall temperature were investigated. These factors significantly affected the wax content during wax deposition. Good agreements were observed between the predictions and experimental results. The variation trends of wax content affected by various aspects are consistent with the existing studies.

An approach to design photonic crystal gas sensor using machine learning

In this paper, a machine learning (ML) based approach is described to design a photonic crystal (PhC) gas sensor for identification and estimation of three greenhouse gases, namely SF6, CH4 and CO2. Exploiting the refractive index dependence of the defect layer positions in the photonic bandgap (PBG) in the transmission spectrum of a PhC, structures are proposed to detect different types of gases. First, a pre-trained classifier is used to identify the gases. Support Vector Machine (SVM) and Random Forest (RF) classifiers are used for performance evaluation with hyper-parameter optimization. Random forest classifier yields the highest accuracy of ∼ 100% for the gas identification stage. In the next step, the densities of the gases are predicted using three pre-trained artificial neural networks (ANNs) separately for each of the gases. The results show that the present approach helps design of a precision gas sensor even using a simple PhC structure.

Lattice vibrations ofγ- andβ-coronene from Raman microscopy and theory

We combine polarization-resolved low frequency Raman microscopy and dispersion-corrected density-functional calculations (DFT-D3) to study polymorph-dependent lattice vibrations in coronene, a model molecular system for nanographenes and disc-like organic semiconductors that exhibits two crystalline structures with distinct electronic and optical properties. Changes in low energy Raman-active lattice phonons are followed across the {\gamma}- to \b{eta}-phase transition at 150 K. Raman frequencies calculated using DFT-D3 agree to within 4 cm-1, and on the basis of polarisation dependence of peak positions and intensities we achieve a clear mode assignment. Studies of the associated atomic motions show how the pure librational and rotational modes of {\gamma}-coronene change into mixed roto-librations in the \b{eta}-phase, explaining the remarkable differences in Raman spectra of the two phases.

The influence of position dependency on surgical success in patients with obstructive sleep apnea undergoing maxillomandibular advancement.

(1) To evaluate surgical success in patients with obstructive sleep apnea undergoing maxillomandibular advancement (MMA) stratifying for the reduction of both the total apnea-hypopnea index (AHI) and the AHI in the supine and nonsupine position; (2) to evaluate the influence of position dependency on surgical outcome; and (3) to analyze the prevalence of residual position-dependent obstructive sleep apnea (OSA) in nonresponders after MMA. A single-center retrospective study including a consecutive series of patients with OSA undergoing MMA between August 2011 and February 2019. In total, 57 patients were included. The overall surgical success was 52.6%. No significant difference in surgical success between nonpositional patients (NPP) and positional patients (PP) with OSA was found. Surgical success of the supine AHI was not significantly different between NPP and PP, but surgical success of the nonsupine AHI was significantly greater in NPP than in PP. Of the 17 preoperative NPP, 13 of them moved to being PP with less severe OSA postoperatively. In total, 21 out of 27 nonresponders (77.8%) were PP postoperatively. No significant difference in surgical success between NPP and PP undergoing MMA was found. However, the improvement of total and nonsupine AHI in NPP was significantly greater compared to PP. In nonresponders, a postoperative shift from severe OSA in NPP to less severe OSA in PP was found, caused by a greater reduction of the nonsupine AHI than the supine AHI postoperatively. In patients with residual OSA in the supine position after MMA, additional treatment with positional therapy can be indicated.

Atomic structure and electronic property of two-dimensional ferroelectric CuInP2Se6

Two-dimensional (2D) CuInP2X6 (X = S or Se) materials have emerged as promising candidates for various technological applications due to their lamellar structures and ferroelectric properties. However, 2D CuInP2Se6 material has not been well explored yet for the difficulty in acquiring ultrathin flakes. Here, we prepare, for the first time, CuInP2Se6 crystals by the chemical vapor deposition method and its 2D flakes, and demonstrate that the thinnest CuInP2Se6 flakes of 4 nm are achieved. X-ray diffraction and atomic-resolution scanning transmission electron microscopy analyses reveal their single crystal phase and the corresponding atomic structure of bulk CuInP2Se6 with good crystallization. Raman results further exhibit obvious thickness dependence of Raman peak position and intensity for the CuInP2Se6 flake. First-principles calculations validate the ferroelectric property of CuInP2Se6 monolayer. Importantly, we find that the antiferroelectric (AFE) state is slightly stable than the ferroelectric (FE) state in bulk form, yet these two states are far more stable than the paraelectric (PE) state, resulting in the coexistence of AFE and FE states in this material.

СИСТЕМА УПРАВЛЕНИЯ УСТРОЙСТВОМ КОНТРОЛЯ ПРИТОКА ФЛЮИДА В СКВАЖИНЕ

Актуальность исследования состоит в том, что решением преждевременного прорыва воды или газа в горизонтальной скважине из-за неоднородности профилей притока вдоль оси горизонтального ствола, является изменение пластового давления на различных участках, а также при разработке контактных месторождений, особенно по мере истощения залежи, могут служить устройства контроля притока флюида. Различают активные Interval Control Valve (ICV) или пассивные Inflow Control Device (ICD) устройства. Устройства ICD способны выровнять приток вдоль горизонтальной скважины за счет создания дополнительного сопротивления потоку жидкости, зависящего от величины притока на данном горизонтальном участке. Недостаток современных ICD в том, что они не имеют возможности регулирования и приведения пассивных устройств в действие после установки в стволе скважины. В связи с тем, что имеются риски связанные с неопределенностью в описании свойств пласта, которые присутствуют на всех стадиях разработки месторождения недостаток ICD оказывается существенным. Системы ICV приводятся в действие дистанционно с поверхности скважины, но не способны определять характер поступающего флюида (нефть, газ, вода) в скважину и принимать решение в автоматическом режиме. Цель: разработка новой конструктивной схемы устройства контроля притоком с возможностью непрерывного мониторинга характера поступающей жидкости, и программного обеспечения для управления клапаном с устья скважины. Объекты: горизонтальная скважина и устройство контроля притоком флюида. Методы: имитационное моделирование Simulink, нейронные сети, матричные методы, методы линеаризации нелинейных уравнений. Результаты. Предложена новая конструктивная схема устройства контроля притока в горизонтальной скважине, позволяющая непрерывно оценивать характер поступающего флюида. Данная конструкция позволяет в автоматическом режиме регулировать положение исполнительного механизма по данным измерительных приборов. Дано математическое описание работы клапана. Разработана модель клапана в среде моделирования Simulink, с использованием матричного подхода и нейронных сетей, для построения качественной зависимости положения клапана от значения создаваемого перепада давления. Приведены результаты работы блока нейронной сети и конечный результат моделирования.

A unified creep interaction factor to characterize multiple cracks interaction at elevated temperatures

Multiple cracks are inevitable to simultaneously occur in components, the growth and coalescence of which greatly reduced loading capacity of defected components at elevated temperatures. Considering the driving force of crack growth determined by the equivalent creep strain ahead of crack front, this paper proposed a unified creep interaction factor based on the ratio of the equivalent creep strain area between multiple cracks and single crack at the same creep strain isoline. This proposed interaction factor successfully demonstrated the interaction among coplanar cracks, eliminated the dependence of position along the crack front and retain the development trend of the maximum creep interaction. The proposed unified factor was greatly influenced by crack depth and creep hardening exponent, besides crack distance. Moreover, through the analyses of the variation of the crack growth rate in the cases of multiple cracks or single crack, the combination rule of multiple cracks could be determined by the value of the interaction level and thus the criteria for combination of interacting multiple cracks was proposed.

Investigation of carrier localization in InAs/AlSb type-II superlattice material system

We investigate carrier localization in the InAs/AlSb type-II superlattice (T2SL) material system using temperature- and excitation power (Iex)-dependent photoluminescence (PL). Evidence of carrier localization in T2SLs was observed by an S-shaped temperature dependence of the PL peak position. Analysis of the Iex-dependent PL at various temperatures also shows the existence of carrier localization in the T2SLs. The thermal activation energies in T2SLs were extracted to identify the nonradiative recombination mechanisms and the possible origins of localized states. We found that there are two thermal activation energies, E1 = 8.2–1.2 meV and E2 = ∼60 meV at various Iex. We interpret E1 as a thermal activation energy that comes from Anderson localization, associated with roughness due to As2 diffusion into the interfaces. This is because the extracted E1 values are comparable to the exciton binding energy of localization in various quantum structures. Carrier trapping at a state in the InSb interfacial layer (Tamm state) may account for the origin of E2. Based on previous reports, we believe that the 60 meV state might be a Tamm state if we consider thickness variations in the InSb interfacial layer for the T2SLs.

Spectroscopic properties of Cu2+ in alkaline earth metaphosphate, fluoride-phosphate and fluoride-phosphate-sulfate glasses

Abstract Divalent copper ions (Cu2+) are not only important colorants in consumer glasses. They can also be used as a probe for assessing the local structural arrangement within a solid host. Here, we report on the incorporation of Cu2+ into alkaline earth metaphosphate (MP), fluoride-phosphate (FP) and fluoride-phosphate-sulfate (FPS) glasses. As a d9 transition metal ion, Cu2+ exhibits a broad optical absorption band at wavelengths of 740–880 nm when incorporated into oxide glasses. The specific properties of this band are strongly affected by the local basicity of the host, which reflects in a straightforward dependence of the band position on the mean-field optical basicity in alkaline earth MP. For FP and FPS, however, distinct deviations from this simplistic correlation are found due to selective cation localization on the various oxoanions and/or halogen species. In addition, high basicity favours the formation of monovalent Cu+. Electron paramagnetic resonance indicates a transition from tetragonally distorted octahedral coordination of Cu2+ in MP to rhombohedral distortion in FP and FPS glasses.

Optical Wave Microphone Measurements for Understanding the Mechanism of Acoustic Emission From Atmospheric Plasma Jet

The author has developed and utilized a unique optical technique called an optical wave microphone to detect pressure waves including acoustic waves emitted from a plasma jet. In previous studies regarding a dielectric barrier plasma jet, acoustic waves were successfully detected with the optical wave microphone and their spatial distribution and frequency property were reported. In this paper, the author aimed to reveal the mechanism of the acoustic wave formation. To achieve the purpose, the helium plasma jet was operated by a single pulse of sinusoidal applied voltage to distinguish acoustic waves originated from each pulsed discharge and evaluate frequency and polarity dependencies. The mechanism of shockwaves formation at the moment of plasma generation was analyzed by changing the frequency of the applied voltage. The gas flow rate and measurement position dependence on the frequency property of detected optical wave microphone waveforms were investigated. Finally, a continuous acoustic emission was realized by synchronizing the specific frequency of the acoustic waves and the applied voltage frequency.

Human Sensation of Transcranial Electric Stimulation

Noninvasive transcranial electric stimulation is increasingly being used as an advantageous therapy alternative that may activate deep tissues while avoiding drug side-effects. However, not only is there limited evidence for activation of deep tissues by transcranial electric stimulation, its evoked human sensation is understudied and often dismissed as a placebo or secondary effect. By systematically characterizing the human sensation evoked by transcranial alternating-current stimulation, we observed not only stimulus frequency and electrode position dependencies specific for auditory and visual sensation but also a broader presence of somatic sensation ranging from touch and vibration to pain and pressure. We found generally monotonic input-output functions at suprathreshold levels, and often multiple types of sensation occurring simultaneously in response to the same electric stimulation. We further used a recording circuit embedded in a cochlear implant to directly and objectively measure the amount of transcranial electric stimulation reaching the auditory nerve, a deep intercranial target located in the densest bone of the skull. We found an optimal configuration using an ear canal electrode and low-frequency (<300 Hz) sinusoids that delivered maximally ~1% of the transcranial current to the auditory nerve, which was sufficient to produce sound sensation even in deafened ears. Our results suggest that frequency resonance due to neuronal intrinsic electric properties need to be explored for targeted deep brain stimulation and novel brain-computer interfaces.