Determination of the scope of the experimental-calculation method for measuring the touch voltage

The work is devoted to the improvement of methods for determining the normalized parameters of the grounding system (GS) of operating power stations and substations. The aim of the work is determination of the scope of the experimental-calculated method for measuring the touch voltage, depending on short-circuit (SC) current value for the given dimensions of the GS and the type of soil. Methodology. The study analyzed the non-linear effect of the SC current value on the touch voltage, taking into account such factors as the GS size and the soil type. The calculation used statistical data on the GS size and the characteristics of the soil obtained by monitoring the GS state of 585 operating electrical substations with a voltage class of 110-750 kV using the induction method and the method of vertical soil sounding, respectively. For the calculation, a mathematical model of a non-equipotential GS located in a three-layer semiconductor space with plane-parallel boundaries was used, this model was developed using the method of integro-differential equations. Results. To determine the scope of the method, in this work it is proposed to use the linearity criterion, which is determined due to the ratio of the constant of reduced touch voltage to the current value. The example shows the method for determining the threshold minimum and maximum values of the measuring current of the soil, in the range between which the measurements by experimental-calculated methods are impossible. A table of threshold current values has been formed and recommendations have been developed on the possibility of using experimental-measuring methods for determining the touch voltage depending on the GS size and soil characteristics.Метою роботи є визначення області застосування експериментально-розрахункового методу вимірювання напруги дотику в залежності від значення струму короткого замикання для заданих розмірів заземлювального пристрою (ЗП) та типу ґрунту. В дослідженні було проаналізовано нелінійний вплив величини струму КЗ на напругу дотику з урахуванням таких факторів як розмір ЗП та тип ґрунту. Для розрахунку була використана математична модель нееквіпотенційного ЗП, розташованого у тришаровому напівпровідному просторі з плоско-паралельними границями поділу, що була розроблена за допомогою методу інтегро-диференційних рівнянь. Для визначення області застосування методу в роботі запропоновано використовувати критерій лінійності, який визначається через відношення сталої приведеної напруги дотику до поточного значення. Сформовано таблицю значень порогових струмів та розроблено рекомендації щодо можливості використання експериментально-вимірювальних методів визначення напруги дотику в залежності від розміру ЗП та характеристик ґрунту

Method of integro-differential equations for interpreting the results of vertical electrical sounding of the soil

The paper is devoted to the problem of determining the geoelectric structure of the soil within the procedure of testing the grounding arrangements of existing power plants and substations to the required depth in conditions of dense development. To solve the problem, it was proposed to use the Schlumbergers method , which has a greater sounding depth compared to the Wenner electrode array. The purpose of the work is to develop a mathematical model for interpreting the results of soil sounding by the Schlumberger method in the form of a four-layer geoelectric structure. Methodology. To construct a mathematical model, it is proposed to use the solution of a particular problem about the field of a point current source, which, like the observation point, is located in the first layer of a four-layer soil. Based on this expressions, a system of linear algebraic equations of the 7-th order with respect to the unknown coefficients ai and bi was compiled. On the basis of its analytical solution, an expression for the potential of the electric field was obtained for conducting VES (the point current source and the observation point are located only on the soil surface). Results. Comparison of the results of soil sounding by the Schlumberger installation and the interpretation of its results for the same points shows a sufficient degree of approximation: the maximum relative error does not exceed 9.7 % (for the second point), and the average relative error is 3.6 %. Originality. Based on the obtained expression, a test version of the program was implemented in Visual Basic for Applications to interpret the results of VES by the Schlumberger method. To check the obtained expressions, the interpretation of the VES results was carried out on the territory of a 150 kV substation of one of the mining and processing plants in the city of Kriviy Rih. Practical significance. The developed mathematical model will make it possible to increase the sounding depth, and, consequently, the accuracy of determining the standardized parameters of the grounding arrangements of power stations and substations.Робота присвячена проблематиці визначення геоелектричної структури ґрунту в межах випробування заземлювальних пристроїв діючих електричних станцій та підстанцій на необхідну глибину в умовах щільної забудови. Для вирішення проблеми запропоновано використати установку Шлюмберже, яка має більшу глибину зондування у порівнянні з установкою Веннера. За допомогою методів інтегро-диференційних рівнянь було отримано аналітичні вирази для інтерпретації результатів зондування ґрунту установкою Шлюмберже у випадку чотиришарового ґрунту. Для перевірки отриманих виразів була проведена інтерпретація результатів вертикального електричного зондування на території підстанції 150 кВ одного з гірничо-збагачувальних комбінатів: максимальна відносна похибка не перевищує 9,7 %, а середня – 3,6 %

Simulation of electromagnetic processes in the grounding system with a short circuit in the operating high-voltage substation

The aim of the work is a test of the developed mathematical model of electromagnetic processes of short circuit and approbation of the created software complex «LiGro» on its basis for the existing grounding system located in three-layer soil. Methodology. To improve the accuracy of calculating the normalized parameters of operating power stations and substations, the authors developed the «LiGro» software package based on the expressions obtained in for calculating the potential of the electric field of a non-equipotential grounding system (GS). To monitor the state and assess the efficiency of the GS of operating power facilities, the electromagnetic diagnostics is used. The topology of the GS was determined with the induction method by complex KNTR-1, the geoelectric structure of the soil was determined by the method of vertical electrical sounding using the Wenner installation, the interpretation of the sounding results was made by the «VEZ-4A» program. The calculation results show that for the selected substation, the model developed in the «LiGro» complex has a deviation δ2 from the experimental values Ut by an average of 8,2 %, and the model implemented in Grounding 1.0 (IEEE model) δ1 is 17,2 %. Originality. The results of the study confirm the adequacy of the developed GS model in the «LiGro» complex based on a three-layer soil model, with the experimental values of the touch voltage obtained by simulating a single-phase ground fault on a real GS in operation. The first time was made approbation of the «LiGro» software package when performing the EMD of the GS of an operating substation with a voltage class of 150 kV. Practical significance. The program software can be used by special measuring’s laboratory to determining electrical safety parameters: touch voltage, GS voltage, and GS resistance. Метою роботи є перевірка розробленої математичної моделі електромагнітних процесів короткого замикання та апробація створеного програмного комплексу «LiGro на її основі для існуючого заземлювального пристрою (ЗП), який розташовано в тришаровому ґрунті. Перевірка практичного застосування була виконана на діючий підстанції класом напруги 150 кВ з використанням вдосконаленої методики електромагнітної діагностики. Топологія ЗП була визначена індукційним методом за допомогою приладу KNTR-1, параметри ґрунту визначені чотириелектродною симетричною установкою за схемою Веннера методом вертикального електричного зондування, інтерпретація результатів зондування виконана спеціалізованою програмою VEZ-4A. Результати порівняння розрахунку показують, що для обраної підстанції модель розроблена в комплексі LiGro має відхилення від експериментальних значень в середньому на 8,2 %, а модель реалізована в Grounding 1.0 (IEEE model) – 17,2 %. Виконано розрахунок нормованих параметрів ЗП в режимі короткого замикання: напругу дотику, опір ЗП та напругу на ЗП. Встановлено, що вони не перевищують допустимого значення. Проаналізовано переваги розрахункового комплексу у порівнянні з аналогами. Отримані результати дозволяють виконати повномасштабне впровадження програмного комплексу в діагностику стану ЗП.&nbsp

Coherent Population Trapping with Controlled Interparticle Interactions

We investigate Coherent Population Trapping in a strongly interacting ultracold Rydberg gas. Despite the strong van der Waals interactions and interparticle correlations, we observe the persistence of a resonance with subnatural linewidth at the single-particle resonance frequency as we tune the interaction strength. This narrow resonance cannot be understood within a meanfield description of the strong Rydberg--Rydberg interactions. Instead, a many-body density matrix approach, accounting for the dynamics of interparticle correlations, is shown to reproduce the observed spectral features

High-coherence electron and ion bunches from laser-cooled atoms

XXVIII ICPEACCold atom electron and ion sources produce electron bunches and ion beams by photoionisation of laser cooled atoms. They offer high coherence and the potential for high brightness, with applications including ultrafast electron diffractive imaging of dynamic processes at the nanoscale. Here we present our cold atom electron/ion source, with an electron temperature of less than 10 K and a transverse coherence length of 10 nm. We also discuss experiments investigating space-charge effects with ions and the production of ultra-fast electron bunches using a femto-second laser. In the latter experiment we show that it is possible to produce both cold and fast electron bunches with our source.A. J. McCulloch, D. V. Sheludko, C. T. Putkunz, S. D. Saliba, D. J. Thompson, R. W. Speirs, D. Murphy, J. Torrance, B. M. Sparkes, and R. E. Scholte

Determination of the scope of the experimental-calculation method for measuring the touch voltage

The work is devoted to the improvement of methods for determining the normalized parameters of the grounding system (GS) of operating power stations and substations. The aim of the work is determination of the scope of the experimental-calculated method for measuring the touch voltage, depending on short-circuit (SC) current value for the given dimensions of the GS and the type of soil. Methodology. The study analyzed the non-linear effect of the SC current value on the touch voltage, taking into account such factors as the GS size and the soil type. The calculation used statistical data on the GS size and the characteristics of the soil obtained by monitoring the GS state of 585 operating electrical substations with a voltage class of 110-750 kV using the induction method and the method of vertical soil sounding, respectively. For the calculation, a mathematical model of a non-equipotential GS located in a three-layer semiconductor space with plane-parallel boundaries was used, this model was developed using the method of integro-differential equations. Results. To determine the scope of the method, in this work it is proposed to use the linearity criterion, which is determined due to the ratio of the constant of reduced touch voltage to the current value. The example shows the method for determining the threshold minimum and maximum values of the measuring current of the soil, in the range between which the measurements by experimental-calculated methods are impossible. A table of threshold current values has been formed and recommendations have been developed on the possibility of using experimental-measuring methods for determining the touch voltage depending on the GS size and soil characteristics

PO-518 Biomarker signature defines a potential therapeutic subclass of triple negative breast cancer

Introduction: Triple Negative Breast Cancer (TNBC) is associated with a worse prognosis among breast cancer subtypes due to the lack of targeted therapy. The protein phosphatase 2A (PP2A) is a heterogeneous tumour suppressor complex that is tightly regulated in terms of activity and target specificity. Oncogenic inactivation of PP2A is known to be mediated by various mechanisms. The overexpression of inhibitory regulators and increased phosphorylation of PP2A targets have been associated with the TNBC subtype and a worse prognosis. PP2A is predicted to be deregulated in 60% of TNBC and presents a potential target for therapy. Here, we use novel biomarkers, AURKA and KIF2C to identify a TNBC subclass with actionable PP2A deregulation.peer-reviewe

A critical role for IRF5 in regulating allergic airway inflammation

Interferon regulatory factor 5 (IRF5) is a key transcription factor involved in the control of the expression of pro-inflammatory cytokine and responses to infection, however its role in regulating pulmonary immune responses to allergen is unknown. We used genetic ablation, adenoviral vector-driven overexpression and adoptive transfer approaches to interrogate the role of IRF5 in pulmonary immunity and during challenge with the aero-allergen, house dust mite. Global IRF5 deficiency resulted in impaired lung function and extracellular matrix (ECM) deposition. IRF5 was also essential for effective responses to inhaled allergen, controlling airway hyper- responsiveness, mucus secretion and eosinophilic inflammation. Adoptive transfer of IRF5- deficient alveolar macrophages into the WT pulmonary milieu was sufficient to drive airway hyper-reactivity, at baseline or following antigen challenge. These data identify IRF5-expressing macrophages as a key component of the immune defence of the airways. Manipulation of IRF5 activity in the lung could therefore be a viable strategy for the redirection of pulmonary immune responses and thus, the treatment of lung disorders

Consumo dos nutrientes em caprinos alimentados com dietas contendo bagaço de caju desidratado (Anacardium occidentale L.).

Foram avaliados os consumos de nutrientes em dietas contendo bagaço de caju desidratado (BCD) em diferentes níveis de inclusão. O experimento foi conduzido nas dependências do Núcleo de Pesquisas em Forragicultura do Departamento de Zootecnia da Universidade Federal do Ceará. Utilizaram-se doze caprinos com peso vivo inicial de 18,2 kg, distribuídos num delineamento inteiramente casualizado com quatro tratamentos e seis repetições no tempo. As inclusões de bagaço de caju nas dietas foram de 18, 36, 46 e 72%. A estimativa da produção fecal foi avaliada por coleta total. Os consumos de todos os nutrientes avaliados aumentaram (P<0,01) linearmente com a inclusão do BCD às dietas. Somente o maior nível de inclusão (72%) atendeu aos requisitos do NRC (2007) para consumo de matéria seca, enquanto os consumos de proteína bruta foram atendidos parcialmente nos níveis acima de 18% de inclusão e totalmente em 72%. Foram encontrados valores de 199,19 a 440,04g FDN/dia para 18 e 72% de inclusão, respectivamente