DTN Trustworthiness for Permafrost Telemetry IoT Network

The SHETLAND-NET research project aims to build an Internet of Things (IoT) telemetry service in Antarctica to automatize the data collection of permafrost research studies on interconnecting remote wireless sensor networks (WSNs) through near vertical incidence skywave (NVIS) long fat networks (LFN). The proposed architecture presents some properties from challenging networks that require the use of delay tolerant networking (DTN) opportunistic techniques that send the collected data during the night as a bulk data transfer whenever a link comes available. This process might result in network congestion and packet loss. This is a complex architecture that demands a thorough assessment of the solution’s viability and an analysis of the transport protocols in order to find the option which best suits the use case to achieve superior trustworthiness in network congestion situations. A heterogeneous layer-based model is used to measure and improve the trustworthiness of the service. The scenario and different transport protocols are modeled to be compared, and the system’s trustworthiness is assessed through simulations.

A Heterogeneous Layer-Based Trustworthiness Model for Long Backhaul NVIS Challenging Networks and an IoT Telemetry Service for Antarctica

Antarctica is a key location for many research fields. The lack of telecommunication systems that interconnect remote base camps hardens the possibility of building synergies among different polar research studies. This paper defines a network architecture to deploy a group of interconnected remote Antarctic wireless sensor networks providing an IoT telemetry service. Long backhaul NVIS links were used to interconnect remote networks. This architecture presents some properties from challenging networks that require evaluating the viability of the solution. A heterogeneous layer-based model to measure and improve the trustworthiness of the service was defined and presented. The model was validated and the trustworthiness of the system was measured using the Riverbed Model simulator.

Mathematical modeling of well operation in the case of two-dimensional filtration in an anisotropic heterogeneous layer

Поставлена плоская (двумерная) задача о математическом моделировании работы скважины в анизотропном неоднородном пласте грунта с раздельной анизотропией и неоднородностью, когда контур питания произвольный. Рассматривается совершенная скважина, когда она полностью вскрывает пласт своей рабочей частью (фильтром). Проницаемость грунта характеризуется тензором второго ранга, компоненты которого моделируются степенной функцией координат. Гомеоморфным аффинным преобразованием координат эта задача приводится к каноническому виду, что значительно упрощает ее исследование. Получено в конечном виде аналитическое решение задачи о дебите скважины с конкретным эллиптическим контуром питания, а также в случае, когда контур питания удален в бесконечность. В случае произвольного гладкого контура питания задача о дебите редуцирована к системе сингулярного интегрального уравнения и интегрального соотношения, которая решена численно методом дискретных особенностей. Исследовано влияние на дебит анизотропии, неоднородности пласта и формы контура питания. A flat (two-dimensional) problem has been posed on the mathematical modeling of well in an anisotropic inhomogeneous reservoir of soil with separate anisotropy and heterogeneity when the power contour is arbitrary. The considered well completely opens the formation with its working part (filter). Such a well is called perfect. The permeability of the soil is characterized by a second-rank tensor whose components are modeled by a power function of the coordinates. With a homeomorphic affine transformation of coordinates, this problem is reduced to a canonical form which greatly simplifies its study. An analytical solution of the problem of well production with an elliptical power contour is obtained in the final form as well as in the case when the power contour is removed to infinity. In the general case, the problem is reduced to a system of integral equations and the integral relation. The results were obtained in the general case using the discrete singularities method. The influence on the flow rate of anisotropy, heterogeneity of the reservoir and the shape of the power contour was studied.

Comment on “Laboratory Measurement and Analysis of the Deteriorated Layer Permeability Coefficient of Soil–Cement Deteriorated in a Saline Environment”

The derivation of a formula to compute the permeability coefficient in the commented paper assumes that the mass flow is homogeneous in a homogeneous layer of a specimen. This assumption is not correct when there is also, at least, one heterogeneous layer. Moreover, a mathematical lapse was found on one equation, that would prevent the right computation of the permeability coefficient, even if the assumption was correct. Although this does not invalidate the major conclusions of the study and has not an outstanding effect on the presented results, for the sake of rigor and sound background for future studies in this field, corrections to the published formulas and model are proposed.

Computer analysis of workpieces auto-heating during surfacing

The method for calculating of the temperature when surfacing of complex-shaped workpiece by solving non-stationary and nonlinear equation of thermal conductivity in heterogeneous layer, which allows taking into account the elements of the clamping device and not describing numerous boundary conditions is presented. Example for calculating of the heating temperature of spherical plug of the ball valve during surfacing on spherical surface via welding deposition with spiral and back-and-forth movement of the heat source is given. The calculated temperature variation in the base material during the surfacing of specifi c workpieces makes it possible to develop program for adjusting of the surfacing mode to ensure the stability of the dimensions and properties of the deposited layer.