Application of Sharafutdinov's Ray Transform in Integrated Photoelasticity

We explain the main concepts centered around Sharafutdinov's ray transform, its kernel, and the extent to which it can be inverted. It is shown how the ray transform emerges naturally in any attempt to reconstruct optical and stress tensors within a photoelastic medium from measurements on the state of polarization of light beams passing through the strained medium. The problem of reconstruction of stress tensors is crucially related to the fact that the ray transform has a nontrivial kernel; the latter is described by a theorem for which we provide a new proof which is simpler and shorter as in Sharafutdinov's original work, as we limit our scope to tensors which are relevant to Photoelasticity. We explain how the kernel of the ray transform is related to the decomposition of tensor fields into longitudinal and transverse components. The merits of the ray transform as a tool for tensor reconstruction are studied by walking through an explicit example of reconstructing the $\sigma_{33}$-component of the stress tensor in a cylindrical photoelastic specimen. In order to make the paper self-contained we provide a derivation of the basic equations of Integrated Photoelasticity which describe how the presence of stress within a photoelastic medium influences the passage of polarized light through the material

Study of change in the leaching solution activity after treatment with a cavitator

Purpose. Increasing the valuable component content in a pregnant solution due to the activation of leaching solution with cavitation treatment in case of the borehole in-situ leaching (ISL). Methods. To obtain the cavitation effect, a laboratory cavitation plant has been produced. Studies on the sulphuric acid solution activation by means of cavitation were conducted using solutions with 10 g/l of acid content. Studies of changing the sulphuric acid solution activity during treatment with a cavitator were conducted for 3 minutes (24 passes through the cavitator), 5 minutes (40 passes), 10 minutes (80 passes) and 20 minutes (160 passes). The content in the solution of the valuable component was analysed using a KFK-3-“ZOMS” photoelectric photometer. Findings. The laboratory studies have been performed to set the influence of the cavitation process on the leaching solution activity at various degrees of activation and time of reaction. The studies have established that in order to activate the leaching solution, it is proposed to carry out cavitation treatment of sulphuric acid before to additionally fortify the mother solution, which helps to increase its activity. The solution activation leads to an increase in the valuable component content from 18 to 26% in the pregnant solution and its activity is maintained for a long time (up to 30 days). Originality. New dependences have been obtained reflecting the nature of changing the valuable component content in the pregnant solution on the reaction time and the degree of solution activation. Practical implications. The proposed activation method leads to an increase in the valuable component content in the pregnant solution compared to the basic technology, therewith, the activity is maintained for a long time. The proposed technology is characterized by low capital costs, is easily integrated into the existing system and is absolutely environmentally friendly.Мета. Підвищення вмісту корисного компоненту в продуктивному розчині за рахунок активації вилуговуючого розчину кавітаційною обробкою при підземному свердловинному вилуговуванні. Методика. Для отримання ефекту кавітації була виготовлена лабораторна кавітаційна установка. Дослідження з активації сірчанокислотного розчину кавітацією проведені на розчинах з вмістом кислоти 10 г/л. Дослідження зміни активності сірчанокислотного розчину при обробці кавітатором проводили протягом 3 хвилин (24 проходи через кавітатор), 5 хвилин (40 проходів), 10 хвилин (80 проходів) і 20 хвилин (160 проходів). Аналіз вмісту корисного компонентау в розчині вели з використанням фотоелектричного фотометра КФК-3-“ЗОМС”. Результати. Виконані лабораторні дослідження зі встановлення впливу процесу кавітації на активність вилуговуючого розчину при різному ступені активації та часу реакції. Дослідженнями встановлено, що для активації вилуговуючого розчину пропонується проводити кавітаційну обробку сірчаної кислоти перед дозміцненням маточного розчину, що сприятиме підвищенню її активності. Активація розчину призводить до збільшення вмісту корисного компоненту в продуктивному розчині від 18 до 26% і її активність зберігається протягом тривалого часу (до 30 днів). Наукова новизна. Отримано нові залежності, що відображають характер зміни вмісту корисного компоненту в продуктивному розчині від часу реакції та ступеня активації розчину. Практична значимість. Запропонований спосіб активації призводить до збільшення вмісту корисного компоненту в продуктивному розчині у порівнянні з базовою технологією, при цьому активність зберігається протягом тривалого часу. Запропонована технологія відрізняється низькими капітальними витратами, легко інтегрується в існуючу систему й екологічно абсолютно безпечна.Цель. Повышение содержания полезного компонента в продуктивном растворе за счет активации выщелачивающего раствора кавитационной обработкой при подземном скважинном выщелачивании. Методика. Для получения эффекта кавитации была изготовлена лабораторная кавитационная установка. Исследования по активации сернокислотного раствора кавитацией проведены на растворах с содержанием кислоты 10 г/л. Исследования изменения активности сернокислотного раствора при обработке кавитатором проводили в течение 3 минут (24 прохода через кавитатор), 5 минут (40 проходов), 10 минут (80 проходов) и 20 минут (160 проходов). Анализ содержания полезного компонента в растворе вели с использованием фотоэлектрического фотометра КФК-3-“ЗОМС”. Результаты. Выполнены лабораторные исследования по установлению влияния процесса кавитации на активность выщелачивающего раствора при различной степени активации и времени реакции. Исследованиями установлено, что для активации выщелачивающего раствора предлагается проводить кавитационную обработку серной кислоты перед доукреплением маточного раствора, что способствует повышению ее активности. Активация раствора приводит к увеличению содержания полезного компонента в продуктивном растворе от 18 до 26% и ее активность сохраняется длительное время (до 30 дней). Научная новизна. Получены новые зависимости, отражающие характер изменения содержания полезного компонента в продуктивном растворе от времени реакции и степени активации раствора. Практическая значимость. Предложенный способ активации приводит к увеличению содержания полезного компонента в продуктивном растворе по сравнению с базовой технологией, при этом активность сохраняется длительное время. Предлагаемая технология отличается низкими капитальными затратами, легко интегрируется в существующую систему и экологически абсолютно безопасна.This research was conducted as part of the business contract implementation with JV “Akbastau”, No. 281/ Akb-16 of 23 December, 2016 and as part of the research-development work “Development of technology for mining and extraction of gold from poor ore veins”, performed within the framework of the program “Mo-dernization of technologies and production in the mining and mining-processing industries of the republic of Kazakhstan”, No. 266 of 28 March, 2018. The authors express their gratitude to Doctor of Technical Sciences, Professor H.A. Yusupov, Professor G.G. Kurapov and to Chief Research Scientist S.A. Yusupov for assistance and valuable advice in conducting this research

Full-field pulsed magneto-photoelasticity – Experimental Implementation

This paper contains a description of the experimental procedure employed when using a pulsed-magneto-polariscope (PMP) and some initial full-field through-thickness measurements of the stress distribution present in samples containing 3D stresses. The instrument uses the theory of magneto-photoelasticity (MPE), which is an experimental stress analysis technique that involves the application of a magnetic field to a birefringent model within a polariscope. MPE was developed for through-thickness stress measurement where the integrated through-thickness birefringent measurement disguises the actual stress distribution. MPE is mainly used in toughened glass where the through-thickness distribution can reduce its overall strength and so its determination is important. To date MPE has been a single-point 2D through-thickness measurement and the analysis time is prohibitive for the investigation of an area which may contain high localised stresses. The pulsed-magneto-polariscope (PMP) has been designed to enable the application of full-field 3D MPE [ ]. Using a proof-of concept PMP several experimental measurements were made, these were promising and demonstrate the potential of the new instrument. Further development of this technique presents several exciting possibilities including a tool for the measurement of the distribution of principal stress difference seen in a general 3D model

Characterizing User-to-User Connectivity with RIPE Atlas

Characterizing the interconnectivity of networks at a country level is an interesting but non-trivial task. The IXP Country Jedi is an existing prototype that uses RIPE Atlas probes in order to explore interconnectivity at a country level, taking into account all Autonomous Systems (AS) where RIPE Atlas probes are deployed. In this work, we build upon this basis and specifically focus on "eyeball" networks, i.e. the user-facing networks with the largest user populations in any given country, and explore to what extent we can provide insights on their interconnectivity. In particular, with a focused user-to-user (and/or user-to-content) version of the IXP Country Jedi we work towards meaningful statistics and comparisons between countries/economies. This is something that a general-purpose probe-to-probe version is not able to capture. We present our preliminary work on the estimation of RIPE Atlas coverage in eyeball networks, as well as an approach to measure and visualize user interconnectivity with our Eyeball Jedi tool.Comment: In Proceedings of the Applied Networking Research Workshop (ANRW '17

Beyond trial-by-trial adaptation : a quantification of the time scale of cognitive control

The idea that adaptation to stimulus or response conflict can operate over different time scales takes a prominent position in various theories and models of cognitive control. The mechanisms underlying temporal variations in control are nevertheless poorly understood, which is partly due to a lack of appropriate empirical measures. Inspired by reinforcement learning models, we developed a method to quantify the time scale of control behaviorally, by computing trial-by-trial effects that go beyond the preceding trial. Briefly, we extended the congruency sequence effect from 1 trial to multiple trials into the past and quantified the influence of previous trials on current-trial performance as a function of trial distance. The rate at which this influence changes across trials was taken as a measure of the time scale of control. We applied the method to a flanker task with different conflict frequencies and volatility. Results showed that the time scale of control was smaller in rare-conflict and volatile contexts, compared to frequent-conflict and neutral contexts. This is in agreement with theories differentiating transient from sustained control. The method offers new opportunities to reveal temporal differences in control modes and can easily be applied to various empirical paradigms. (PsycINFO Database Recordstatus: publishe

Simple individual-based models effectively represent Afrotropical forest bird movement in complex landscapes

Reliable estimates of dispersal rates between habitat patches (i.e. functional connectivity) are critical for predicting long-term effects of habitat fragmentation on population persistence. Connectivity measures are frequently derived from least cost path or graph-based approaches, despite the fact that these methods make biologically unrealistic assumptions. Individual-based models (IBMs) have been proposed as an alternative as they allow modelling movement behaviour in response to landscape resistance. However, IBMs typically require excessive data to be useful for management. Here, we test the extent to which an IBM requiring only an uncomplicated set of movement rules [the 'stochastic movement simulator' (SMS)] can predict animal movement behaviour in real-world landscapes. Movement behaviour of two forest birds, the Cabanis's greenbul Phyllastrephus cabanisi (a forest specialist) and the white-starred robin Pogonocichla stellata (a habitat generalist), across an Afrotropical matrix was simulated using SMS. Predictions from SMS were evaluated against a set of detailed movement paths collected by radiotracking homing individuals. SMS was capable of generating credible predictions of bird movement, although simulations were sensitive to the cost values and the movement rules specified. Model performance was generally highest when movement was simulated across low-contrasting cost surfaces and when virtual individuals were assigned low directional persistence and limited perceptual range. SMS better predicted movements of the habitat specialist than the habitat generalist, which highlights its potential to model functional connectivity when species movements are affected by the matrix. Synthesis and applications. Modelling the dispersal process with greater biological realism is likely to be critical for improving our predictive capability regarding functional connectivity and population persistence. For more realistic models to be widely applied, it is vital that their application is not overly complicated or data demanding. Here, we show that given relatively basic understanding of a species' dispersal ecology, the stochastic movement simulator represents a promising tool for estimating connectivity, which can help improve the design of functional ecological networks aimed at successful species conservation

Improvement of Fourier Polarimetry for applications in tomographic photoelasticity

The use of the Fourier Polarimetry method has been demonstrated to extract the three characteristic parameters in integrated photoelasticity. In contrast to the phase-stepping method, it has been shown that the Fourier method is more accurate. However, the Fourier method isn't very efficient as it requires that a minimum of nine intensity images be collected during a whole revolution of a polarizer while the phase-stepping method only needs six intensity images. In this paper the Fourier transformation is used to derive the expression for determination of the characteristic parameters. Four Fourier coefficients are clearly identified to calculate the three characteristic parameters. It is found that the angular rotation ratio could be set arbitrarily. The angular rotation ratio is optimized to satisfy the requirements of efficiency and proper data accuracy, which results in data collection about three times faster than the methods suggested by previous researchers. When comparing their performance in terms of efficiency and accuracy, the simulated and experimental results show that these angular rotation ratios have the same accuracy but the optimized angular rotation ratio is significantly faster. The sensitivity to noise is also investigated and further improvement of accuracy is suggested

Temporal and spectral variation of desert dust and biomass burning aerosol scenes from 1995?2000 using GOME

International audienceGlobal Ozone Monitoring Experiment (GOME) Absorbing Aerosol Index (AAI) and AAI-related residue data were used to investigate areas with UV-absorbing aerosols. Time series of regionally averaged residues show the seasonal variation and trends of aerosols and clouds in climatologically important parts of the globe. GOME spectra were used to study scenes containing specific types of aerosols. AAI data are specifically sensitive to biomass burning aerosols (BBA) and desert dust aerosols (DDA). Areas where these aerosols are regularly found were analysed to find spectral fingerprints in the ultraviolet (UV), visible and near-infrared (near-IR), to establish an aerosol type classification of BBA and DDA. Spectral residues are different for BBA and DDA, but over deserts the surface albedo is dominant beyond the UV and spectral residues cannot be used over land. Over oceans, about half of the BBA scenes show a very high reflectance that is never observed for DDA scenes. However, in the case of low reflectance scenes BBA and DDA cannot be distinguished. This is in part due to the microphysical and optical properties of biomass burning aerosols, which are highly variable in time, making it difficult to specify them spectrally as one type. Because of their high hygroscopicity BBA are often found in the presence of clouds, which disturb the spectrum of the scenes. Desert dust aerosols are much less hygroscopic and behave spectrally more uniformly