The research of sapropels as the drilling fluids in dispersed phase (Lake Kirek)

This research describes the application of Kirek Lake sapropel as a drilling fluid in dispersed phase which could replace traditionally used clay powders in drilling fluids. Sapropel is century-old bed silt of freshwater lakes of more than 12 000 years, i.e. Holocene. It consists of natural organic and inorganic substances and chemically is a complex multicomponent biogenic genesis system. Humic complexes and wulfonic acids, polysaccharides, carbonic and protein polymers comprise sapropel suspension texture. This article introduces formulations and laboratory research of sapropel suspensions and thermal activation

Synthesis of Carboxymethyl Starch for increasing drilling mud quality in drilling oil and gas wells

This paper describes the impact of carboxymethyl starch preparation conditions on physicochemical properties of polysaccharide reagent, widely used as fluid loss reducing agent in drilling mud. Variation of the main parameters of carboxymethylation is researched in the experiment. The following conditions such as temperature and reaction time, amount of water, as well as ratio of NaOH to monochloracetic acid define the characteristics of carboxymethyl starch. The degree of substitution is defined for polysaccharides, as well as the characteristics of samples have been studied by infrared spectroscopy. Rheological characteristics and fluid loss indicator have been investigated to study the impact of the reagents on drilling mud quality

Long-Wave Instability of Advective Flows in Inclined Layer with Solid Heat Conductive Boundaries

We investigate the stability of the steady convective flow in a plane tilted layer with ideal thermal conductivity of solid boundaries in the presence of uniform longitudinal temperature gradient. Analytically found the stability boundary with respect to the long-wave perturbations, find the critical Grashof number for the most dangerous among them of even spiral perturbation.Comment: in Russian, 18 pages, 5 figures, submited to Appl. mechanics and physics, RAS Siberian brunch, Novosibirsk, Russia; Key words: advective flow, oblique layer, a longitudinal temperature gradient, long-wave instabilit

Synthesis of Carboxymethyl Starch for increasing drilling mud quality in drilling oil and gas wells

This paper describes the impact of carboxymethyl starch preparation conditions on physicochemical properties of polysaccharide reagent, widely used as fluid loss reducing agent in drilling mud. Variation of the main parameters of carboxymethylation is researched in the experiment. The following conditions such as temperature and reaction time, amount of water, as well as ratio of NaOH to monochloracetic acid define the characteristics of carboxymethyl starch. The degree of substitution is defined for polysaccharides, as well as the characteristics of samples have been studied by infrared spectroscopy. Rheological characteristics and fluid loss indicator have been investigated to study the impact of the reagents on drilling mud quality

Extinction times in the subcritical stochastic SIS logistic epidemic

Many real epidemics of an infectious disease are not straightforwardly super- or sub-critical, and the understanding of epidemic models that exhibit such complexity has been identified as a priority for theoretical work. We provide insights into the near-critical regime by considering the stochastic SIS logistic epidemic, a well-known birth-and-death chain used to model the spread of an epidemic within a population of a given size $N$. We study the behaviour of the process as the population size $N$ tends to infinity. Our results cover the entire subcritical regime, including the "barely subcritical" regime, where the recovery rate exceeds the infection rate by an amount that tends to 0 as $N \to \infty$ but more slowly than $N^{-1/2}$. We derive precise asymptotics for the distribution of the extinction time and the total number of cases throughout the subcritical regime, give a detailed description of the course of the epidemic, and compare to numerical results for a range of parameter values. We hypothesise that features of the course of the epidemic will be seen in a wide class of other epidemic models, and we use real data to provide some tentative and preliminary support for this theory.Comment: Revised; 34 pages; 6 figure

Arbitrary trajectory foot planner for bipedal walking

© 2017 by SCITEPRESS - Science and Technology Publications, Lda. All Rights Reserved. This paper presents a foot planner algorithm for bipedal walking along an arbitrary curve. It takes a parametrically defined desired path as an input and calculates feet positions and orientations at each step. Number of steps that are required to complete the path depends on a maximum step length and maximum foot rotation angle at each step. Provided with results of the foot planner, our walking engine successfully performs robot locomotion. Verification tests were executed with AR601M humanoid robot

Comparing fiducial marker systems in the presence of occlusion

© 2017 IEEE. A fiducial marker system is a system of unique 2D (planar) marker, which is placed in an environment and automatically will be detected with a camera with a help of a corresponding detection algorithm. Application areas of these markers include industrial systems, augmented reality, robots navigation, human-robot interaction and others. Marker system designed for such different applications must be robust to such factors as view angles, occlusions, changing distances, etc. This paper compares three existing systems of markers: ARTag, AprilTag, and CALTag. As a benchmark, we use their reliability and detection rate in presence of occlusions of various types and intensity. The paper presents experimental comparison of these markers. The marker detection was performed with a simple inexpensive Web camera

Determination of optimal technology for manufacturing dental surgical guides

© Published under licence by IOP Publishing Ltd. This article describes methods of manufacturing surgical guides - their creation in rapid prototyping installations and milling machine grinding. Implantation was carried out using the obtained guides and derating level of installed implants was defined. The work compares existing technologies of surgical guides production and defines a clear advantage of using laser stereolithography technology for product manufacture in quantities greater than one

Diferenciación entre los conceptos “Protección” y “Preservación” en el Derecho Internacional del Mar.

A la luz del uso intensivo de los espacios y recursos de los grandes océanos, su rápida contaminación se encuentra entre los nuevos desafíos y amenazas para la seguridad de los estados. El sistema de medidas para la protección del Océano Mundial es clave, ya que este último desempeña un papel excepcional para garantizar la vida de nuestro planeta. En función de lo anterior, el derecho internacional juega el papel de designar las acciones a cumplir por los estados necesarias para garantizar la protección y preservación de los océanos. El derecho internacional desempeña dos funciones importantes: reglamentación y protección, donde esta última se define tanto en la ciencia como en la legislación a través de categorías adyacentes como "protección", "defensa" y "preservación".

Acute Adhesive Small Bowel Obstruction: a Comparative Analysis of Open and Laparoscopic Surgery

Background. Acute adhesive small bowel obstruction (AASBO) is a common surgical emergency requiring immediate interventions. AASBO is a usual indication for both small bowel resection and adhesiolysis. Postoperative adhesions cause 60% of small bowel obstructions.Materials and methods. An analysis of treatment outcomes is presented for 197 acute adhesive small bowel obstruction patients; 63 patients had urgent laparotomy, and 134 were scheduled for laparoscopy. The examination included physical, laboratory, radiological methods (abdominal radiography, ultrasound, CT scan), laparoscopy and intra-abdominal pressure monitoring.Results and discussion. Of 134 patients scheduled for laparoscopic adhesiolysis, only 46.2% had laparoscopy completed, and 53.8% required conversion to laparotomy. The main rationale for conversion were massive adhesions, intraoperative haemodynamic instability, a need for intestinal decompression, as well as rare complications. Laparoscopic operations were reported with the lower vs. laparotomy rates of surgical complications (6.4  vs. 12.69%), mortality (6  vs. 6.3%), shorter hospital stays (6.5 vs. 12 days) and operation times (75 vs. 118 min, respectively).Conclusion. Laparoscopic surgery in acute adhesive small bowel obstruction was feasible in 31.47% patients and in 46.2% — after a diagnostic laparoscopy; however, a thorough patients selection for laparoscopic adhesiolysis is necessary. The first estimated should be the patient’s haemodynamic stability, the severities of condition, adhesions and comorbid cardiorespiratory pathology. Grade I—II adhesions are an indication for laparoscopic surgery