Computer Aided Design of Transformer Station Grounding System Using CDEGS Software

This paper presents a computer-aided design of a transformer station grounding system. Fault conditions in a transformer station can produce huge damage to transformer station equipment if the grounding system is not designed properly. A well designed grounding system is a very important part of the project for transformer station design as a whole. This paper analyses a procedure for transformer grounding system design and spatial distribution of touch and step voltage on the ground surface level, using the CDEGS (Current Distribution Electromagnetic Interference Grounding and Soil Structure Analysis) software. Spatial distribution is needed for checking and finding dangerous step and touch voltages above and around the transformer station. Apparent earth resistivity data is measured and analyzed using the RESAP module of the CDEGS software. Because of the very high current flow into the grounding system during a single line to ground fault or a three phase fault in the transformer station, very high and dangerous potentials can be induced on the metallic structures including the fence, which can cause dangerous situations for people and animals near the station and for the personnel inside the station. The PLOT module of CDEGS is used to view the results of the scalar potential, step and touch voltage on the surface. Graphic displays include equipotent contour lines and potential profiles (gradients) in 3D and 2D perspective and apparent soil resistivity (Wm) versus inter electrode spacing (m). The results of alternative grid designs may be displayed simultaneously for the purpose of comparison

Comparison of Field-To-Line Coupling Models: Coupled Transmission Lines Model versus Single-cell Corrected Taylor Model

International audienceModels for field-to-line coupling are interesting be- cause they help to predict the immunity of PCBs and explain the relation between routing and immunity. In this article a meandered PCB trace illuminated by EM field in a TEM cell is analysed. The near-end and far-end coupling is predicted using two models: a detailed and an approximative one. The detailed model is a circuit of coupled multi-conductor transmission lines evaluated with a circuit simulator. The approximative model consists of a single Taylor cell with an analytical modification evaluated using a numerical computing tool. Both predictions are compared with measurements and turn out to be equally precise. The advantage of the coupled lines model is its flexibility, the advantage of the modified Taylor model is its ease of use

ANALYSING THE EFFECT OF DISCONTINUITY OF ELECTRICAL CONDUCTIVITY OF SOIL ON GROUND RESISTANCE

U članku je osim direktne primjene metode odslikavanja prikazana i primjena složenog odslikavanja, koje se javlja u slučajevima s dvije i više granica diskontinuiteta specifične električne vodljivosti. U radu je analiziran utjecaj zanemarenog odslikavanja pri određivanju otpora rasprostiranja uzemljivača, u slučaju kada se tlo modelira kao jednoslojno. Zatim je analizirana pogreška zbog modeliranja jednoslojnog tla koje se po svojoj naravi najtočnije opisuje kao dvoslojno. Prilikom modeliranja tla korištena je tehnika jednostavnog i složenog odslikavanja. Radi jednostavnosti izlaganja i usporedivosti modela za uzemljivač je odabran obični vodoravno ukopan cilindrični vodič. Dobiveni rezultati prikazani su analitički i grafički te objašnjeni.In addition to the direct application of the method of images the article also shows the application of complex images in the cases with two or more discontinuity boundaries of the specific electrical conductivity. The article analyzes the effect of neglected images in determining ground resistance, in a single-layer soil model, and goes on to analyse the error due to modelling single-layer soil which by its characteristics is most accurately described as double-layer. In modelling the soil the technique of simple and complex images was applied. To keep the presentation simple and make the models comparable, a normal horizontally inserted cylindrical conductor was taken as ground conductor. The results obtained are shown analytically and graphically and discussed

SUBSTITUTIONAL MODEL OF THE SOIL BASED ON ARTIFICAL NEURAL NETWORKS

U radu je prikazana interpretacija rezultata mjerenja specifičnog otpora tla primjenom umjetnih neuronskih mreža. Model zasnovan na umjetnim neuronskim mrežama nadomješta tlo koje se fizikalno može smatrati kao dvoslojni medij s vertikalnom promjenom specifičnog električnog otpora i s vodoravnom granicom među slojevima. Učenje umjetne neuronske mreže provedeno je pod nadzorom sa skupom ulaznih podataka koji su dobiveni na temelju vrlo točnog teorijskog modela dvoslojnog tla. Predloženi algoritam; koji aproksimira nelinearne karakteristike tla koristeći umjetne neuronske mreže; pouzdano procjenjuje parametre tla i specifičnu električnu otpornost tla. Primjena nadomjesnog modela tla zasnovanog na neuronskim mrežama prikazana je na praktičnom primjeru određivanja parametara dvoslojnog tla iz mjernih podataka dobivenih Wennerovom tehnikom mjerenja specifičnog otpora tla. Radi jednostavnosti izlaganja i usporedivosti modela strujne sonde (štapovi) su nadomještene kuglastim elektrodama; odnosno točkastim izvorima polja. Dobiveni rezultati su prikazani analitički i grafički te diskutirani.This paper presents an interpretation of the results of measurement of specific soil resistivity by means of artificial neural networks.The model based on artificial neural networks replaces the soil which can be physically considered a two-layer medium with a vertical change of the specific electric resistivity and a horizontal boundary line between the layers. Learning of the neural network was performed under supervision using the input dataset obtained by means of a very accurate theoretical model of the double-layer soil. The proposed algorithm that approximates non-linear soil properties using the artificial neural network is reliable in assessment of the soil parameters and specific electric soil resistivity. Application of the substitutional model of the soil based on neural networks is demonstrated by a realistic example; determination of parameters of the double-layer soil from the measured data obtained by the Wenner technique for measuring the specific soil resistivity. For simplicity of presentation and model comparability; the current probes (poles) are replaced by the ball electrodes; i.e. spot field sources. The results obtained are analytically and graphically presented and discussed

VALIDITY LIMITS OF THE EXPRESSION FOR MEASURING SOIL RESISTIVITY BY THE WENNER METHOD ACCORDING TO IEEE STANDARD 81-1983

Za analizu rezultata i obavljanje mjerenja specifičnog otpora tla inženjerima su dane na raspolaganje smjernice i naputci različitih međunarodnih normi. Prilikom korištenja matematičkih izraza iz navedenih normi često nisu jasne okolnosti pod kojima su dobiveni navedeni izrazi. Jedan takav slučaj opisan je u ovom članku, a odnosi se na međunarodnu normu IEEE Std. 81-1983, izraz za prividni specifični otpor tla, a koji se odnosi na teorijski model i predviđanje mjernih rezultata dobivenih Wennerovim mjernim rasporedom elektroda. U IEEE Std. 81-1983 štapne elektrode su modelirane kao kuglaste, što u konačnici rezultira jednostavnim matematičkim izrazom za prividni specifični otpor tla. Zbog navedenog pojednostavljenja inženjeri nemaju uvid u granice valjanosti prema normi dobivenog izraza, odnosno njegovu točnost. Naime, pretpostavlja se da korisnik ima predznanje visokog obrazovanja, usmjeravajuće struke ili da je pohađao odgovarajuće tečajeve. Iz tog razloga u članku je detaljno prikazan izvod izraza za prividni specifični otpor tla u slučaju kada se mjerenje obavlja Wennerovom mjernom tehnikom. Izvodi su iscrpno komentirani kako bi iznesena građa bila razumljivija što širem krugu čitatelja. Dobiveni izraz uvažava stvarnu geometriju mjernih elektroda i utjecaj međusobne blizine elektroda na mjerenje. Na primjeru iz prakse uspoređeni su rezultati dobiveni izvedenim izrazom s predloženim izrazom prema međunarodnoj normi IEEE Std. 81-1983. Rezultati oba pristupa prikazani su grafički, analitički te diskutirani.For the analysis of soil resistivity results and measurement, engineers have guidelines and instructions from various international standards at their disposal. The circumstances under which the mathematical expressions in these standards were obtained are not always clear. One such case is described in this article and refers to the international IEEE Standard 81-1983, an expression for apparent soil resistivity, and refers to a theoretical model and the prediction and interpretation of measurement results obtained by using the Wenner method of electrode arrangement. In IEEE Std. 81-1983, rod electrodes are modeled as spherical, which ultimately results in a simplified mathematical expression for apparent soil resistivity. Due to this simplification, the expression in this standard does not provide engineers with insight into its validity limits, i.e. accuracy. It is assumed that the user is highly educated, specialized or has obtained the necessary training. Therefore, this article presents the derivation of the expression for apparent soil resistivity in detail when measurement is performed using the Wenner method. Exhaustive commentary on the derivations is provided so that the material presented will be understood by the widest possible circle of readers. The expression obtained takes the actual geometry of the measurement electrodes and the influence of the distance between the electrodes upon measurement into account. Using a practical example, the results obtained using the derived expression are compared to results obtained using the expression proposed according to the international IEEE Std. 81-1983. The results of both approaches are presented graphically and analytically, and are discussed

Genotype–phenotype correlation in contactin-associated protein-like 2 (CNTNAP-2) developmental disorder

Contactin-associated protein-like 2 (CNTNAP2) gene encodes for CASPR2, a presynaptic type 1 transmembrane protein, involved in cell–cell adhesion and synaptic interactions. Biallelic CNTNAP2 loss has been associated with “Pitt-Hopkins-like syndrome-1” (MIM#610042), while the pathogenic role of heterozygous variants remains controversial. We report 22 novel patients harboring mono- (n = 2) and bi-allelic (n = 20) CNTNAP2 variants and carried out a literature review to characterize the genotype–phenotype correlation. Patients (M:F 14:8) were aged between 3 and 19 years and affected by global developmental delay (GDD) (n = 21), moderate to profound intellectual disability (n = 17) and epilepsy (n = 21). Seizures mainly started in the first two years of life (median 22.5 months). Antiseizure medications were successful in controlling the seizures in about two-thirds of the patients. Autism spectrum disorder (ASD) and/or other neuropsychiatric comorbidities were present in nine patients (40.9%). Nonspecific midline brain anomalies were noted in most patients while focal signal abnormalities in the temporal lobes were noted in three subjects. Genotype–phenotype correlation was performed by also including 50 previously published patients (15 mono- and 35 bi-allelic variants). Overall, GDD (p < 0.0001), epilepsy (p < 0.0001), hyporeflexia (p = 0.012), ASD (p = 0.009), language impairment (p = 0.020) and severe cognitive impairment (p = 0.031) were significantly associated with the presence of biallelic versus monoallelic variants. We have defined the main features associated with biallelic CNTNAP2 variants, as severe cognitive impairment, epilepsy and behavioral abnormalities. We propose CASPR2-deficiency neurodevelopmental disorder as an exclusively recessive disease while the contribution of heterozygous variants is less likely to follow an autosomal dominant inheritance pattern

Compressed σ-protocol theory and practical application to plug & play secure algorithmics

Σ-Protocols provide a well-understood basis for secure algorithmics. Recently, Bulletproofs (Bootle et al., EUROCRYPT 2016, and Bünz et al., S&P 2018) have been proposed as a drop-in replacement in case of zero-knowledge (ZK) for arithmetic circuits, achieving logarithmic communication instead of linear. Its pivot is an ingenious, logarithmic-size proof of knowledge BP for certain quadratic relations. However, reducing ZK for general relations to it forces a somewhat cumbersome “reinvention” of cryptographic protocol theory. We take a rather different viewpoint and reconcile Bulletproofs with Σ-Protocol Theory such that (a) simpler circuit ZK is developed within established theory, while (b) achieving exactly the same logarithmic communication. The natural key here is linearization. First, we repurpose BPs as a blackbox compression mechanism for standard Σ-Protocols handling ZK proofs of general linear relations (on compactly committed secret vectors); our pivot. Second, we reduce the case of general nonlinear relations to blackbox applications of our pivot via a novel variation on arithmetic secret sharing based techniques for Σ-Protocols (Cramer et al., ICITS 2012). Orthogonally, we enhance versatility by enabling scenarios not previously addressed, e.g., when a secret input is dispersed across several commitments. Standard implementation platforms leading to logarithmic communication follow from a Discrete-Log assumption or a generalized Strong-RSA assumption. Also, under a Knowledge-of-Exponent Assumption (KEA) communication drops to constant, as in ZK-SNARKS. All in all, our theory should more generally be useful for modular (“plug & play”) design of practical cryptographic protocols; this is further evidenced by our separate work (2020) on proofs of partial knowledge

Towards a Smart Contract-based, Decentralized, Public-Key Infrastructure

Public-key infrastructures (PKIs) are an integral part of the security foundations of digital communications. Their widespread deployment has allowed the growth of important applications, such as, internet banking and e-commerce. Centralized PKIs (CPKIs) rely on a hierarchy of trusted Certification Authorities (CAs) for issuing, distributing and managing the status of digital certificates, i.e., unforgeable data structures that attest to the authenticity of an entity\u27s public key. Unfortunately, CPKIs have many downsides in terms of security and fault tolerance and there have been numerous security incidents throughout the years. Decentralized PKIs (DPKIs) were proposed to deal with these issues as they rely on multiple, independent nodes. Nevertheless, decentralization raises other concerns such as what are the incentives for the participating nodes to ensure the service\u27s availability. In our work, we leverage the scalability, as well as, the built-in incentive mechanism of blockchain systems and propose a smart contract-based DPKI. The main barrier in realizing a smart contract-based DPKI is the size of the contract\u27s state which, being its most expensive resource to access, should be minimized for a construction to be viable. We resolve this problem by proposing and using in our DPKI a public-state cryptographic accumulator with constant size, a cryptographic tool which may be of independent interest in the context of blockchain protocols. We also are the first to formalize the DPKI design problem in the Universal Composability (UC) framework and formally prove the security of our construction under the strong RSA assumption in the Random Oracle model and the existence of an ideal smart contract functionality

Severity-adjusted evaluation of liver transplantation on health outcomes in urea cycle disorders

Purpose: Liver transplantation (LTx) is performed in individuals with urea cycle disorders when medical management (MM) insufficiently prevents the occurrence of hyperammonemic events. However, there is a paucity of systematic analyses on the effects of LTx on health-related outcome parameters compared to individuals with comparable severity who are medically managed. Methods: We investigated the effects of LTx and MM on validated health-related outcome parameters, including the metabolic disease course, linear growth, and neurocognitive outcomes. Individuals were stratified into “severe” and “attenuated” categories based on the genotype-specific and validated in vitro enzyme activity. Results: LTx enabled metabolic stability by prevention of further hyperammonemic events after transplantation and was associated with a more favorable growth outcome compared with individuals remaining under MM. However, neurocognitive outcome in individuals with LTx did not differ from the medically managed counterparts as reflected by the frequency of motor abnormality and cognitive standard deviation score at last observation. Conclusion: Whereas LTx enabled metabolic stability without further need of protein restriction or nitrogen-scavenging therapy and was associated with a more favorable growth outcome, LTx—as currently performed—was not associated with improved neurocognitive outcomes compared with long-term MM in the investigated urea cycle disorders.</p