Optimizing site-specific specimen preparation for Atom Probe Tomography by using hydrogen for visualizing radiation-induced damage

Atom probe tomography (APT) is extensively used to measure the local chemistry of materials. Site-specific preparation via a focused ion beam (FIB) is routinely implemented to fabricate needle-shaped specimens with an end radius in the range of 50 nm. This preparation route is sometimes supplemented by transmission Kikuchi diffraction (TKD) to facilitate the positioning of a region of interest sufficiently close to the apex. Irradiating the specimen with energetic electrons and ions can lead to the generation of vacancies and even amorphization of the specimen. These extrinsically created vacancies become crucial for probing the hydrogen or deuterium distribution since they act as a strong trap. Here, we investigated the feasibility of site-specific preparation of a two-phase medium-Mn steel containing austenite (fcc) and ferrite (bcc). Following gaseous charging of APT specimens in deuterium (D2), clusters enriched by up to 35 at.% D, are imaged after Pt deposition, conventional Ga-FIB preparation, and TKD conducted separately. These D-rich clusters are assumed to arise from the agglomeration of vacancies acting as strong traps. By systematically eliminating these preparation-induced damages, we finally introduce a workflow allowing for studying intrinsic traps for H/D inherent to the material

Differences in Sensory Characteristics and Aroma Compounds between Young and Aged Qingxiangxing Baijiu

The characteristic aroma compounds of qingxiangxing baijiu were analyzed and the differences in sensory characteristics and aroma compounds between young and aged baijiu were clarified by sensory evaluation and techniques for qualitative and quantitative analysis of aroma compounds. Totally 69 odor-active compounds with flavor dilution (FD) factor ≥ 2 were confirmed by comparative aroma extract dilution analysis (CAEDA). A total of 40 odor-active compounds in young qingxiangxing baijiu and 43 in aged qingxiangxing baijiu were identified based on odor activity value (OAV). The important aroma compounds of young and aged baijiu were verified by aroma recombination experiments. Finally, heatmap analysis showed that the differential important aroma compounds (P ≤ 0.05) between young and aged qingxiangxing baijiu mainly included γ-butyrolactone, ethyl isovalerate, γ-nonanolactone, ethyl isobutyrate, 3-methylbutanoic acid, 1,1-diethoxyethane, β-phenylethanol, 2-pentyl furan, acetaldehyde, butanoic acid, ethyl hexanoate, benzaldehyde, furfural, vanillin, hexanal, 3-hydroxy-2-butanone, and 2,3-butanedione. In summary, microconstituents were more abundant in aged than young baijiu, and so were most esters, organic acids, aldehydes, and ketones, while the opposite was found for propanol, isobutanol, and 3-methylbutanol. These could be the major reasons for the significant differences in the sensory characteristics of young and aged baijiu

Charakterystyka wytrzymałościowa próbek kompozytowych składających się z warstw węgla i materiału skalnego o różnej wysokości pod wpływem obciążeń jednoosiowych

An uniaxial compression mechanical model for the roof rock-coal (RRC) composite sample was establi-shed in order to study the effects of height ratio of roof rock to coal on the structural strength of composite sample. The composite sample strengths under different height ratios were established through stress and strain analysis of the sample extracted from the interface. The coal strength near the interface is enhanced and rock strength near the interface weakened. The structural strength of composite sample is synthetically determined by the strengths of rock and coal near and far away from the interface. The area with a low strength in composite sample is destroyed firstly. An analytical model was proposed and discussed by conducting uniaxial compression tests for sandstone-coal composite samples with different height ratios, and it was found that the structural strength and elastic modulus decrease with a decrease in height ratio. The coal strengths far away from the interface determine the structural strengths of composite sample under different height ratios, which are the main control factor for the structural strength in this test. Due to its lowest strength, the rock near the interface first experienced a tensile spalling failure at the height ratio of 9:1, without causing the structural failure of composite sample. The coal failure induces the final failure of composite sample.Model mechaniczny modelu stropu w postaci próbek kompozytowych składających się z węgla i materiału skalnego pod działaniem obciążeń jednoosiowych został opracowany w celu zbadania wpływu stosunku wysokości warstwy stropu skalnego do warstwy węgla na wytrzymałość próbki kompozytowej. Wytrzymałość na ściskanie próbek kompozytowych dla różnych wielkości stosunku wysokości warstw określono na podstawie badania naprężeń i odkształceń próbek pobranych ze strefy kontaktu węgiel-skała. Wytrzymałośćwęgla w pobliżu strefy kontaktowej wzrasta podczas gdy wytrzymałość warstwy skalnej w tym rejonie jest zredukowana. Wytrzymałość próbki kompozytowej określana jest poprzez analizę wytrzymałości warstw węgla i warstw skały w pobliżu a także w pewnej odległości od strefy kontaktowej. W pierwszej kolejności zniszczeniu ulegnie część próbki kompozytowej o zmniejszonej wytrzymałości. Zaproponowano model analityczny i przeprowadzono dyskusję wyników otrzymanych na podstawie testów ściskania jednoosio-wego próbki składającej się z węgla i piaskowca o różnym stosunku wysokości ich warstw. Stwierdzono, że wytrzymałość oraz wartość modułu sprężystości maleje wraz z malejącym stosunkiem wysokości warstw. Wytrzymałość węgla w znacznej odległości od strefy kontaktowej determinuje całkowitą wytrzymałośćpróbki kompozytowej dla różnych stosunków ich wysokości, a stosunek wysokości ich warstw okazuje się być głównym czynnikiem decydującym o wytrzymałości próbki. Z uwagi na najniższą wytrzymałość, warstwa skalna zalegająca najbliżej strefy kontaktu w pierwszej kolejności podległa rozwarstwieniu wskutek rozciągania, przy stosunku wysokości warstw 9:1, nie powodując jednak uszkodzenia próbki kompozytowej. Uszkodzenie warstwy węgla z kolei, prowadzi do całkowitego zniszczenia próbki kompozytowej

Research on Identification and Measurement Methods of Influencing Factors of Investment in Operation and Maintenance

Operation and maintenance investment is an important part of the capital expenditure of power grid enterprises. In recent years, affected by multiple profit-cutting factors such as the macroeconomic downturn, the slowdown in electricity growth, the implementation of transmission and distribution price reform requirements, the narrowing of electricity price space, and the state's phased reduction of electricity cost policies, the profitability of power grid companies has dropped significantly, and power grid investment. The capacity was significantly weakened, and the operating pressure was unprecedented. Identifying and measuring the influencing factors of power grid operation and maintenance investment is an important supporting role for enterprises to formulate scientific and reasonable investment strategies for power grid equipment operation and maintenance. Therefore, this paper first applies the fish-bone method, combined with the current status of equipment operation and maintenance management of power grid enterprises, and scientifically identifies the factors that affect the investment level of operation and maintenance; then, based on the grey correlation theory, analyzes the degree of influence of each influencing factor

Progressive Failure and Acoustic Emission Characteristics of Red Sandstone with Different Geometry Parallel Cracks under Uniaxial Compression Loading

The geometric distribution of initial damages has a great influence on the strength and progressive failure characteristics of the fractured rock mass. Initial damages of the fractured rock were simplified as parallel cracks in different geometric distributions, and then, the progressive failure and acoustic emission (AE) characteristics of specimens under the uniaxial compression loading were analyzed. The red sandstone (brittle materials) specimens with the parallel preexisting cracks by water jet were used in the tests. The energy peak and stress attenuation induced by the energy release of crack initiation were intuitively observed in the test process. Besides, three modes of rock bridge coalescence were obtained, and wing crack was the main crack propagation mode. The wing crack and other cracks were initiated in different loading stages, which were closely related to the energy level of crack initiation. The propagation of wing crack (stable crack) consumed a large amount of energy, and then, the propagation of shear crack, secondary crack, and anti-wing crack (unstable crack) was inhibited. The relationship between the crack propagation mode and the geometric distribution of existing cracks in the specimen was revealed. Meanwhile, the strength characteristic and failure mode of fractured rock with the different geometric distributions of preexisting crack were also investigated. The energy evolution characteristics and crack propagation were also analyzed by numerical modeling (PFC2D)

Use of fly-ash slurry in backfill grouting in coal mines

Cave backfill grouting implies grouting of the caving rock mass prior to it being compacted. The filling materials strengthen the caving rock and support the overlying strata to achieve the purpose of slowing down the surface subsidence. The broken roof will fail and collapse during mining operations performed without appropriate supporting measures being taken. It is difficult to perform continuous backfill mining on the working face of such roofs using the existing mining technology. In order to solve the above problems, fly ash and mine water are considered as filling materials, and flow characteristics of fly-ash slurry are investigated through laboratory experiments and theoretical analyses. Laws governing the diffusion of fly-ash slurry in the void of caving rock masses and in the void between a caving rock mass and a basic roof are obtained and verified. Based on the results obtained from the above analyses and actual conditions at the Zhaoguan coal mine, Shandong Province, China, a cave backfill grouting system of the hauling pipeline is developed and successfully tested at the 1703 working face in the Zhaoguan coal mine. The results demonstrate that a filling rate of 43.46% is achieved, and the surface subsidence coefficient of the grouting process is found to be 0.475. Compared to the total caving method, the proposed system is found to achieve a reduction rate of 40.63%. This effectively helps in lowering the value of the surface subsidence coefficient. Fly ash and mine water, considered as primary materials in this study, also play a significant role in improving the air quality and water environment

A New Approach of Disaster Forecasting Based on Least Square Optimized Neural Network

The evaluation of the risk is the prerequisite for the implementation of countermeasures in the prevention and control of rock burst, and the research on the fast forecast at scene of the rock burst is more important for the safety production of coal mine. Aiming at the problem that dynamic disasters caused by many factors and heterogeneity of coal and rock are difficult to predict in the process of coal mining, in this paper, the general law and the risk control factors of the rock burst are studied, a mathematical model based on the BP neural network was built according to the different actual mining conditions in the mining area, and the output layer has obtained the prediction result. Then, the results of the output samples after training were fitted by using SPSS software, and the fitting function was obtained by multiple least square fitting. Finally, the fitting results are checked by the data of actual coal mine dynamic disaster parameters. The prediction results show that the simulation results of BP neural network prediction model and the fitting function of the least square method can reduce the impact of subjective judgment on the prediction results, and the application of the fitting function can obtain the prediction results in the first time to ensure the construction safety. The method of on-site hazard assessment and inspection by using fitting function is simple and feasible and has high accuracy, which provides a new idea for the field prediction of rock burst

Infrared and Visible Image Fusion Based on Visual Saliency Map and Image Contrast Enhancement

The purpose of infrared and visible image fusion is to generate images with prominent targets and rich information which provides the basis for target detection and recognition. Among the existing image fusion methods, the traditional method is easy to produce artifacts, and the information of the visible target and texture details are not fully preserved, especially for the image fusion under dark scenes and smoke conditions. Therefore, an infrared and visible image fusion method is proposed based on visual saliency image and image contrast enhancement processing. Aiming at the problem that low image contrast brings difficulty to fusion, an improved gamma correction and local mean method is used to enhance the input image contrast. To suppress artifacts that are prone to occur in the process of image fusion, a differential rolling guidance filter (DRGF) method is adopted to decompose the input image into the basic layer and the detail layer. Compared with the traditional multi-scale decomposition method, this method can retain specific edge information and reduce the occurrence of artifacts. In order to solve the problem that the salient object of the fused image is not prominent and the texture detail information is not fully preserved, the salient map extraction method is used to extract the infrared image salient map to guide the fusion image target weight, and on the other hand, it is used to control the fusion weight of the basic layer to improve the shortcomings of the traditional ‘average’ fusion method to weaken the contrast information. In addition, a method based on pixel intensity and gradient is proposed to fuse the detail layer and retain the edge and detail information to the greatest extent. Experimental results show that the proposed method is superior to other fusion algorithms in both subjective and objective aspects