THERMAL-INDUCED DOMAIN PROCESSES IN TRIGLYCINE SULFATE CRYSTALS WITH CHROMIUM IMPURITIES

В работе представлены результаты исследований термоиндуцированных доменных процессов в хромсодержащих кристаллах триглицинсульфата. Показано, что изменение температуры кристаллов ТГС: Cr в отсутствие внешних электрических полей сопровождается перестройкой доменной структуры, которая наиболее интенсивно происходит в области фазового перехода. Деполяризующее поле величиной ~1,4·10 В·м, которое порождается градиентным изменением температуры образца, вызывает процесс переключения его доменной структуры. В неотожженных кристаллах при концентрациях примеси, превышающих 5·10 вес. % процессы переключения затруднены, а интенсивность термоиндуцированных доменных процессов существенно ниже аналогичных для образцов с меньшим содержанием примеси. На интенсивность процессов переключения кристаллов ТГС: Cr существенное влияние оказывает скорость их нагревания. Зависимости интегрального числа скачков переполяризации от скорости нагревания образцов N = f (V) носят экстремальный характер. Экстремумы кривых N = f (V) лежат в интервалах скоростей (0,2-0,8) K·c. Доменная структура кристаллов ТГС:Cr состоит из матрицы основного домена, линзовидных и ламелеобразных доменов. Под воздействием электронного пучка наблюдается эволюция доменной структуры, сопровождающаяся ростом доменов, их слиянием и переключением образца. Высокотемпературный отжиг кристаллов приводит к их полидоменизации. The article presents the results of studies of thermally induced domain processes in chromium-containing crystals of triglycine sulfate (TGS). It is shown that a change in the temperature of TGS: Cr crystals in the absence of external electric fields is accompanied by a rearrangement of the domain structure, that occurs most intensively in the region of the phase transition. A depolarizing field of ~1,4·10 V·m, which is generated by a gradient change in the temperature of the sample, causes the process of switching its domain structure. In unannealed crystals at impurity concentrations exceeding 5·10 wt.%, switching processes are hindered, and the intensity of thermally induced domain processes is significantly lower than that for samples with a lower impurity content. The intensity of the switching processes of TGS: Cr crystals is significantly influenced by the rate of their heating. The dependences of the integral number of polarization-reversal jumps on the heating rate of the samples N = f (V) are extreme. The extrema of the N = f (V) curves lie in the rate intervals (0,2 - 0,8) K·c. The domain structure of TGS: Cr crystals consists of a matrix of the main domain, lenticular and lamellar domains. Evolution of the domain structure is observed under the influence of an electron beam, accompanied by the growth of domains, their coalescence, and sample switching. High-temperature annealing of crystals leads to their polydomenization.

Efficiently, accurately, intelligently dissecting bamboo: characteristic of vascular bundle in Phyllostachys

A comprehensive understanding of vascular bundles is the key to elucidate the excellent intrinsic mechanical properties of bamboo. This research aims to investigate the gradient distribution of fiber volume fraction and the gradient changes in the shape of vascular bundles along the radial axis in Phyllostachys. We constructed a universal transfer-learning-based vascular bundle detection model with high precision of up to 96.97%, which can help to acquire the characteristics of vascular bundles quickly and accurately. The total number of vascular bundles, total fiber sheath area, the length, width and area of fiber sheath of individual vascular bundles within the entire cross-section were counted, and the results showed that these parameters had a strongly positive linear correlation with the outer circumference and wall thickness of bamboo culms, but the fiber volume fraction (around 25.5 %) and the length-to-width ratio of the vascular bundles (around 1.226) were relatively constant. Furthermore, we layered the cross section of bamboo according to the wall thickness finely and counted the characteristics of vascular bundle in each layer. The results showed that the radial distribution of fiber volume fraction decreased exponentially, the radial distribution of the length-to-width ratio of vascular bundle decreased quadratically, the radial distribution of the width of vascular bundle increased linearly. The trends of the gradient change in vascular bundle’s characteristics were found highly consistent among 29 bamboo species in Phyllostachys.One sentence summaryA universal vascular bundle detection model can efficiently dissect vascular bundles in Phyllostachys, and the radial gradient change of vascular bundles in cross-section are found highly consistent.

Open Platform Cameras Based Bio-Imaging Evaluation System

With the active development of mobile devices, a variety of ultra-small, high-definition, and open platform-based cameras are being mass-produced. In this paper, we established an emulation system to verify the bio-imaging performance of the bulky and expensive high-performance cameras and various smartphone cameras that have been used in bio-imaging devices. In the proposed system, the linearity of the brightness gradient change of four types of cameras was compared and analyzed. Based on these results, three cameras were selected in order of excellent linearity, and gel image analysis results were compared.

The Effects of Inlet Flow Rates and Slenderness Ratio on the Separation Performance of a Horizontal Three-Phase Separator

Summary In the first part of this work, the development of a capital cost optimization model for sizing three-phase separators was described. The developed model uses generalized reduced gradient nonlinear algorithms to determine the minimum cost associated with the construction of horizontal separators subject to four sets of constraints. In the second part, an experimental test rig was designed and used to investigate the effect of gas flow rate, liquid flow rate, and slenderness ratio (L/D) on the separation performance of horizontal three-phase separators. The results indicated an inverse relationship between an increase in gas and liquid flow rate and the separator outlet quality. It also indicated a direct relationship between an increase in slenderness ratio and separator outlet quality. The results also showed that the gradient change of the percentage of water in the oil outlet with respect to slenderness ratio decreased to ratios of 6:1. Hence, the separation rate increased. At ratios greater than 6:1, the separation still increases, but the gradient change in separation drops off, implying that the benefit in terms of separation is diminishing beyond this point. Therefore, the optimal slenderness ratio for technical reasons is 6:1.

Preparation of Gradient Materials with Molten Salts Electrodeposition

A new way of preparing W–Cu functional gradient materials (FGM) with molten salts electrodeposition is studied. The results show that, with the conditions of current density 70 mA·cm−2, electrodeposition temperature 700 °C and bidirectional pulse electrodepositing for 30 minutes (min), the Cu–Ni gradient layer prepared under this condition is widely used dense and smooth. Fundamental to the preparation of Cu–Ni functional gradient layer, Cu–Ni is used as a cathode to deposit W. Under the current density of 50 mA·cm−2, the time of 20 min, with bidirectional pulse electrodeposition, the Cu+Ni+W gradient layer has uniform composition gradient change and larger thickness. The W–Cu gradient materials prepared in this study have good cohesiveness. The addition of Ni would promote the inter-diffusion of Cu and W, and increase the diffusion coefficient significantly.

Offline-Online Change Detection for Sentinel-1 InSAR Time Series

Traditional applications of Interferometric Synthetic Aperture Radar (InSAR) data involved inverting an interferogram stack to determine the average displacement velocity. While this approach has useful applications in continuously deforming regions, much information is lost by simply fitting a line through the time series. Thanks to regular acquisitions across most of the the world by the ESA Sentinel-1 satellite constellation, we are now in a position to explore opportunities for near-real time deformation monitoring. In this paper we present a statistical approach for detecting offsets and gradient changes in InSAR time series. Our key assumption is that 5 years of Sentinel-1 data is sufficient to calculate the population standard deviation of the detection variables. Our offset detector identifies statistically significant peaks in the first, second and third difference series. The gradient change detector identifies statistically significant movements in the second derivative series. We exploit the high spatial resolution of Sentinel-1 data and the spatial continuity of geophysical deformation signals to filter out false positive detections that arise due to signal noise. When combined with near-real time processing of InSAR data these detectors, particularly the gradient change, could be used to detect incipient ground deformation associated with geophysical phenomena, for example from landslides or volcanic eruptions.

Offline-Online Change Detection for Sentinel-1 InSAR Time Series

<p>Traditional applications of Interferometric Synthetic Aperture Radar (InSAR) data involved inverting an interferogram stack to determine the average displacement velocity. While this approach has useful applications in continuously deforming regions, new tools are needed for automatically and regularly identifying changes in the time series. Thanks to regular acquisitions across most of the world by the ESA Sentinel-1 satellites constellation, we are now in a position to explore opportunities for near-real time deformation monitoring. In this paper we present a statistical approach for detecting offsets and gradient changes in InSAR time series. Our key assumption is that 5 years of Sentinel-1 data is sufficient to calculate the population standard deviation of the detection variables. Our offset detector identifies statistically significant peaks in the first, second and third difference series. The gradient change detector identifies statistically significant movements in the second derivative series. We exploit the high spatial resolution of Sentinel-1 data and the spatial continuity of geophysical deformation signals to filter out false positive detections that arise due to signal noise. When combined with near-real time processing of InSAR data these detectors, particularly the gradient change, could be used to detect incipient ground deformation associated with geohazards such as landslides or volcanic eruptions.</p>

Propagation of video pulse signals in dissipative media

The results of the numerical solution of the problem of propagation of an electromagnetic video pulse signal of nanosecond duration in a dissipative medium are presented for use in the deep georadar data interpretation. Based on the developed scheme for integrating Maxwell's equations, the results of numerical modeling of the propagation of electromagnetic pulses of various shapes without approximations, usually used in the traditional solution of GPR problems, including the separation of temporal and spatial variables of the electromagnetic field and neglect of the rapid field change in comparison with the processes occurring in the medium, are obtained. The influence of the pulse shape on the shape of the electromagnetic echo signal is considered for various models of the medium close to real conditions, including those with a gradient change in electrical conductivity and permittivity. The influence of the distribution of electrical conductivity of the medium is studied.