Gas Carrier Research Articles

Prevalence and predicting factors of Group A beta-hemolytic Streptococcus carrier state in primary schoolchildren.

Introduction:Transmission of Group A Streptococcus from asymptomatic children to their surrounding carries a risk of acute rheumatic fever in susceptible people.Aim and Objectives:We aimed to investigate the prevalence and predictors of GAS carrier state and evaluate the antibiotic sensitivity pattern of GAS in Jakarta, Indonesia.Material and Methods:We enrolled 201 asymptomatic schoolchildren (6–12 years) using stratified random sampling from a primary school in Jakarta. None of the children had a history of rheumatic fever or rheumatic heart disease. All participants underwent physical examination, and laboratory tests include complete blood count, erythrocyte sedimentation rate, C-reactive protein, antistreptolysin O titer, and throat swab culture.Results:The prevalence of GAS carrier was 13.9% (95% confidence interval: 9.2%–18.6%) in our study. On multivariate analysis, tonsillar enlargement was found to be the only predicting factor of GAS carrier (P = 0.03). GAS was sensitive to penicillin G, erythromycin, vancomycin, clindamycin, chloramphenicol, azithromycin, and tetracycline in 100%, 89%, 86%, 75%, 68%, 68%, and 32% of patients, respectively.Conclusion:The GAS carrier state is common among school-age children affecting approximately 13.9% children. Tonsillar enlargement is a significant finding predictive of GAS carrier state. All isolates are still sensitive to penicillin and mostly sensitive to erythromycin but are increasingly resistant to tetracycline.

Automatic assistance system for visual control of targets

The article discusses the possibility of creating a system for automating the process of searching and assessing the danger of targets using machine vision and existing ship systems. The technologies for processing images from the ship’s camera system are analyzed: object recognition by a ready-made convolutional neural retrained network, as well as object detection by SURF algorithms. The parameters of the danger of goals within the framework of the problem to be solved have been analyzed and developed, and a structural analysis has been elaborated. The functionality of the automatic operation of the system as a closed circuit has been considered. To achieve the technical result in the system as an integrated part of the ship’s equipment based on cognitive information processing, a composite information object from the ship’s sensors and control systems was introduced. It is decomposed into blocks in which the associated logical information processing takes place using basic modules consisting of adaptive cells-approximators as learning elements capable of independently processing information. The following units are included in the local area network: an information support unit (ISU), a decision making unit (DMU), a command-organizational unit (COU) with an operator’s workstation. The ISU is connected by a two-way communication output with aggregate LAN units, the other output is connected in series with a situation determination unit and the “model of the surrounding space” block. The survey was carried out on board a modern LNG gas carrier using ship systems.

Microstructure and Mechanical Properties of GTAW Welded Joint of Invar Alloy

Experiment of automatic gas tungsten arc welding of liquefied natural gas carrier Invar alloy with a thickness of .7 mm was completed, and the welding parameters were optimized, as well as microstructure and mechanical properties of the welded joint were measured and analyzed. The grain size of the area near the weld centerline was small, mainly cellular dendrites, and the grain size on both sides of the weld centerline increased gradually, mainly dendrites, whereas the grain size near fusion line was larger, and there were more columnar crystals. The heat-affected zone was composed of coarse austenite grains. Transgranular cracks were the main cracks in the welding seam. When welding current was 40 A, frequency was 120 Hz, and welding speed was 350 mm/min, tensile strength of the welded joint was 446.9 MPa, which 88.1% of the base metal’s tensile strength and 10.3% of the fracture elongation. The fracture surface of tensile specimens showed typical plastic fracture characteristics, with no obvious crack characteristics, and no eutectic liquid films were observed. Introduction Invar alloy is a Fe–36%Ni alloy. Its thermal expansion coefficient at room temperature is less than 1.6X10-6/k, which is about one-tenth of that of low carbon steel, and changes little in a larger temperature range. Therefore, Invar alloy is widely used in making precision measuring instruments and low temperature-resistant materials (Corbacho et al. 1998; Park et al. 2011; Qiu et al. 2016; Yakout et al. 2018). In recent years, with the increasing demand for clean energy, liquefied natural gas (LNG) carriers are developing rapidly (Zhao et al. 2015; Oh et al. 2018). LNG liquefies at temperatures below -161.5°C. The volume of LNG is about 1/ 625 of the volume of gaseous natural gas of the same mass; thus, it can transport large quantities of natural gas over long distances.

Effects of process-induced residual stress and geometric characteristics on pressure-resisting capability of corrugation in primary barriers of liquefied natural gas carriers

The primary barrier of a liquefied natural gas (LNG) carrier generally has a corrugated shape, so as to withstand thermal shrinkage at cryogenic temperatures. Over the years, studies have been actively performed to improve the performance of the primary barrier through structural analysis. However, when analyzing the pressure-resisting capability of the corrugation, previous studies have not considered the residual stress generated during the forming process of the corrugation. This can lead to an overestimation of the pressure-resisting capability of the corrugation. In this work, the pressure-resisting capabilities of the corrugation were evaluated by considering the residual stress generated during the deep drawing process of the corrugation; the initial buckling mode was also considered through a linear buckle analysis based on a finite element analysis. Universal hydraulic test equipment was developed for measuring the pressure-resisting capabilities of corrugations of various sizes. By comparing the analytical results from the experiments, it was confirmed that the pressure-resisting capability of the corrugation decreased by 16% when the residual stress and initial buckling mode were considered simultaneously. We believe that this study can be used as a reference to present guidelines when setting design parameters to improve the pressure-resisting capability of a primary barrier.

Experimental investigation on effect of sloshing on ship added resistance in head waves

Engineering practice presents some impact of sloshing and ship motion interaction on added resistance in waves, and this paper is an attempt to figure out the effect of such impact through experiment while theoretical investigation is troubling scholars due to the complexity of this problem. A Liquefied Natural Gas (LNG) carrier scaled to 1/27.384, with one prismatic tank, is modeled for free running tests in regular head waves of 6 different wavelengths in the deepwater towing tank of China Scientific Research Center (CSSRC). For each wave case, the revolution rate of propeller, the ship speed, and corresponding torque and thrust are measured, and the added resistance is thereafter obtained by subtracting the still water resistance from the mean total resistance on assumption of a constant thrust deduction. The experimental results are comparatively discussed in conditions of sloshing and ballast weight. It is found that under current test conditions, internal sloshing affects ship motion by reducing its value, and the added resistance in waves decreases accordingly while the energy consumption decreases. The experimental results that liquid sloshing has an evident influence on the added resistance shall be a very important consideration for the development of green LNG cargos.

Crack Propagation Analysis for IMO Type-B Independent Tank with Liquefied Natural Gas Carrier

Crack Propagation Analysis for IMO Type-B Independent Tank with Liquefied Natural Gas Carrier

Sublimation thermodynamics of antifungal drugs: Tioconazole, miconazole and climbazole

The temperature dependence of the saturated vapour pressure of the antifungal drugs – tioconazole (TCZ), miconazole (MCZ) and climbazole (CLZ) – was determined by the inert gas carrier transfer method. The standard molar enthalpies of sublimation at T = 298.15 K calculated from these data were 117.2 ± 0.5 kJ·mol-1 for TCZ ± 0.9, 106.2 ± 1.0 kJ·mol-1 for MCZ and 113.3 kJ·mol-1for CLZ. The vaporization and sublimation enthalpies of the compounds were found by the Langmuir and Clausius-Clapeyron equations without determining the vapour pressures of the drugs. Sublimation enthalpies derived by both these methods were in good agreement. It was shown that it was possible to estimate the thermodynamic sublimation functions by applying the space clusterization approach to the studied and structurally related compounds. In addition, the temperature and enthalpy of fusion of the compounds were measured by differential scanning calorimetry.

(IMCS Second Place Best Poster Award) In-Situ Analysis of Volatile Organic Compounds in Biogas Fermentation Processes Using a Metal Oxide Gas Sensor Array

(IMCS Second Place Best Poster Award) In-Situ Analysis of Volatile Organic Compounds in Biogas Fermentation Processes Using a Metal Oxide Gas Sensor Array

Mitigating the Agglomeration of Nanofiller in a Mixed Matrix Membrane by Incorporating an Interface Agent.

Nanodiamonds (ND) have recently emerged as excellent candidates for various applications including membrane technology due to their nanoscale size, non-toxic nature, excellent mechanical and thermal properties, high surface areas and tuneable surface structures with functional groups. However, their non-porous structure and strong tendency to aggregate are hindering their potential in gas separation membrane applications. To overcome those issues, this study proposes an efficient approach by decorating the ND surface with polyethyleneimine (PEI) before embedding it into the polymer matrix to fabricate MMMs for CO2/N2 separation. Acting as both interfacial binder and gas carrier agent, the PEI layer enhances the polymer/filler interfacial interaction, minimising the agglomeration of ND in the polymer matrix, which is evidenced by the focus ion beam scanning electron microscopy (FIB-SEM). The incorporation of PEI into the membrane matrix effectively improves the CO2/N2 selectivity compared to the pristine polymer membranes. The improvement in CO2/N2 selectivity is also modelled by calculating the interfacial permeabilities with the Felske model using the gas permeabilities in the MMM. This study proposes a simple and effective modification method to address both the interface and gas selectivity in the application of nanoscale and non-porous fillers in gas separation membranes.

Influence of Silica-Aerogel on Mechanical Characteristics of Polyurethane-Based Composites: Thermal Conductivity and Strength.

Polyurethane foam (PUF) has generally been used in liquefied natural gas (LNG) carrier cargo containment systems (CCSs) owing to its excellent mechanical and thermal properties over a wide range of temperatures. An LNG CCS must be designed to withstand extreme environmental conditions. However, as the insulation material for LNGC CCSs, PUF has two major limitations: its strength and thermal conductivity. In the present study, PUFs were synthesized with various weight percentages of porous silica aerogel to reinforce the characteristics of PUF used in LNG carrier insulation systems. To evaluate the mechanical strength of the PUF-silica aerogel composites considering LNG loading/unloading environmental conditions, compressive tests were conducted at room temperature (20 °C) and a cryogenic temperature (−163 °C). In addition, the thermal insulation performance and cellular structure were identified to analyze the effects of silica aerogels on cell morphology. The cell morphology of PUF-silica aerogel composites was relatively homogeneous, and the cell shape remained closed at 1 wt.% in comparison to the other concentrations. As a result, the mechanical and thermal properties were significantly improved by the addition of 1 wt.% silica aerogel to the PUF. The mechanical properties were reduced by increasing the silica aerogel content to 3 wt.% and 5 wt.%, mainly because of the pores generated on the surface of the composites.

Towards the Autonomy: Control Systems for the Ship in Confined and Open Waters.

The concept of the Marine Autonomous Surface Ship (MASS) requires new solutions in many areas: from law, through economics, social sciences, environmental issues to the technology and even ethics. It also plays a central role in the work of numerous research teams dealing with the ship motion control systems. This article presents the results of the experiments with application of the selected control methods in automatic steering of the movement of an autonomous ship in the two regimes: during the maneuvers at low speed (in a harbor confined waters) and during the lake trials in open water conditions. In the first case, multidimensional state controller synthesized with Linear Matrix Inequalities (LMI) algorithms was used, while, in the second case, Model Predictive Control (MPC) control was adopted. The object for which the experiments were carried out was 1:24 scale model of the Liquefied Natural Gas (LNG) carrier. The paper presents also the design of the measurement and control system and the user interface. The experiments were conducted in the natural conditions on the lake. The results of the experiments indicate the fundamental role of the measurement system in the process of controlling an autonomous ship.

Ion wind enhances plasma jets for sterilization, eliminating the need for large gas systems

Existing atmospheric pressure plasma require massive gas carrier equipment, making their potential sterilization applications a challenge.

Evaluation of the pressure-resisting capability of membrane-type corrugated sheet under hydrodynamic load

Fluid impact load-induced collapse of the corrugated sheet in the primary barrier of liquefied natural gas carrier (LNGC) cargo containment systems is recognized as one of the most dangerous deformation phenomena because it leads to catastrophic failure of the containment system. Thus, significant efforts have been dedicated to precisely evaluating the load-carrying capacity of the primary barrier. However, due to the lack of testing methods and the complex geometry of the corrugated primary barrier sheet, the structural behavior of the sheet under impact-induced pressure has rarely been investigated. The aim of this study is to develop design support methodology ensuring the integrity of the primary barriers in LNG cargo containment systems. A custom-built experimental facility was developed to create uniform pressurization on the primary barrier sheet. The out-of-plane deformations of the sheet were observed over time during the experiment. To create a reliable numerical method applicable in the design stage, a series of parametric studies using finite element analyses (FEA) were conducted. Based on the comparison between the numerical solutions and experimental results, a practical method to estimate the typical deflection patterns based on the corrugation type was developed. Thus, we demonstrate that the insights from experimental observations as well as FEA techniques can be used in the practical design support methodology.

CFD numerical simulations of inertia stopping of a very large gas carrier using overset grid technology and body-force propeller

With the development of International shipping, waterways all over the world are becoming increasingly crowded. Research on inertia stopping ability of large ships is essential to voyage safety. At present, the inertial stopping of ship is mainly measured by ship model test, and there is little work to study the performance using CFD technology. STARCCM+based on the ship 6-DOF motion and overset grid technology and body-force method are used to numerically simulate the inertia stopping maneuver of a very large gas carrier. By controlling the rotation speed of the propeller, the ship is in a stable state of motion. Then set the speed to zero.The motion state and detailed flow field information of the ship model during motion can be got by solving viscous flow field. To verify the accuracy of numerical prediction results, ship model test is launched. Both the trajectory of the ship and the value of the characteristic parameter match very well.

Catalytic reforming of acetic acid as main primary tar compound from biomass updraft gasifiers: screening of suitable catalysts and operating conditions

Tar compounds have been defined as Achilles’ heel in biomass gasification. Catalytic reforming solves problems caused by tar by converting them into H2 and CO. Most of the research has focused on secondary and tertiary tar reforming while some information on primary tar can be derived from bio-oil reforming. However, these studies use humidified N2, Ar or He as gas carrier. Therefore, in this work, three catalysts are compared for reforming 40 g/Nm3 acetic acid as main primary tar compound from biomass updraft gasification using simulated biosyngas as gas carrier. The catalysts were tested over a 72 h period between 680 and 750 °C with a gas composition of 35.0 vol% H2O, 2.3 vol% CO, 19.5 vol% CO2, 3.6 vol% CH4, 24.0 vol% H2 and 15.6 vol% N2. Olivine completely converted acetic acid, but a considerable amount of carbonaceous deposits was found on the catalyst and the catalytic activity decreased over time with 0.2 g/Nm3 hydroxyacetone measured in the last day of testing. Dolomite showed promising performances by completely converting acetic acid and accumulating carbonaceous deposits only in the low temperature part of the catalyst bed. The carbonaceous deposits could be suppressed increasing the steam content to 50.1 vol% and the temperature to 900 °C. However, the catalyst became excessively brittle. The metal-based catalyst out-performed the naturally-occurring catalysts by completely converting acetic acid with almost no carbonaceous deposits accumulation. These results are expected to help the further development of tar reformers, and the commercialisation of biomass updraft gasifiers based systems.

Reproducible and rapid synthesis of a conjugated polymer by Stille polycondensation in flow: Effects of reaction parameters on molecular weight

The batch-to-batch variations in molecular weight and molecular weight dispersity (Đ) values are large for conjugated polymers synthesized by step-growth polymerization, which can lead to irreproducible device performance. We developed a rapid flow synthesis system that can perform step-growth polymerizations of conjugated polymers in a reproducible manner by utilizing nitrogen gas as a carrier. The use of gas carrier, instead of organic solvents or fluorinated oils, eliminates the common diffusion problems at the beginning and the end of the reaction stream to the carrier fluid. Without the diffusion problem, our system provides high reproducibility and uniform reaction conditions in all regions of reaction stream. To highlight the performance of our flow system, we conducted Stille polycondensations to synthesize a representative conjugated polymer, PTB7. We found that PTB7 with a number average molecular weight (Mn) over 30 kDa was synthesized in only 3 min, with very low deviations of 2.6% and 3.1% for Mn and Đ values, respectively, compared to deviations of 66% for Mn and 43% for Đ in control reactions using pure solvent as a carrier. The effect of catalyst loading and reaction temperature was also studied, which enabled tuning the Mn of PTB7 within the range of 30.6–57.9 kDa. The quality of PTB7 synthesized in our system was also confirmed by fabricating photovoltaic devices which gave maximum power conversion efficiency of 7.02% with PC71BM as an acceptor.

Spatiotemporal statistical characteristics of multiphase flow behaviors in fuel reactor for separated-gasification chemical looping combustion of solid fuel

Separated-gasification chemical looping combustion (SGCLC) has high conversion efficiency for solid fuels. Fuel reactor (FR) in SGCLC is designed as a gasifier (GR) and a connected reduction reactor (RR) with gas, sand and oxygen carrier (OC) phases. In order to clearly know the multiphase flow characteristics, a FR prototype is designed and the gas-solid hydrodynamics in FR are investigated using computational fluid dynamic (CFD) method. The gas velocity and OC flowrate are changed in simulations to study their effects on flow behaviors. Bubble probability in GR increases from 0 at bottom to 0.64 at 0.33 m while the gas volume fraction reaches 0.80 herein under fundamental condition. Spatiotemporal statistical results of the characteristics of gas and solid phases demonstrate that increasing gas velocity can enhance the heterogeneity of pressure and gas velocity distributions in GR. The mean values of pressure and gas velocity standard deviations increase from 13.71 Pa to 18.66 Pa and from 2.08 m/s to 2.55 m/s at 0.33 m when gas velocity accelerates from 1.8 m/s to 2.2 m/s. On the contrary, it has opposite effect on heterogeneity of pressure distribution in RR. Increasing OC flowrate from 0.6 kg/s to 0.8 kg/s can enlarge OC inventory in RR and enhance the standard deviation of pressure distribution in RR. The mean value of pressure standard deviations in RR increase from 3.12 Pa to 4.82 Pa at 1.85 m. The gas-OC mixing and contact can be improved for sufficient combustion reaction.

Effect of in-flight particle behavior on the morphology of flame sprayed Er2O3 splats

The morphology and microstructure of splats impact the comprehensive capability of a new coating methodology called chelate flame spraying (CFS). This study addresses the quantitative characterization of the spread morphologies of flame sprayed Er2O3 splats directly deposited under different spray conditions on aluminum alloy substrates with a mirror finish. The influence of the in-flight particle temperature and velocity, carrier gas type, and carrier gas ratio on the solidification mechanism of molten droplets was investigated. Image analysis methods were employed to identify single splats from the morphology observed with field-emission scanning electron microscopy (FE-SEM). In addition, Er2O3 films were synthesized on an Al–Mg alloy (A5052) substrate using N2 or O2 as the carrier gas. When O2 was used as the carrier gas, 109-μm-thick films were deposited on the A5052 substrate. The cross-sectional porosity of the films was 3.8%. In contrast, films with 101-μm thickness were synthesized on the A5052 substrate when N2 was used as the carrier gas. The cross-sectional porosity of these films was 13.8%. The results showed that the carrier gas type (N2) and carrier gas ratio had a significant effect on the flattening behavior of the molten droplets. A spraying method combined with multidimensional modes is proposed to control the morphology of the splats.

Geopolitical risk and the LNG-LPG trade

We explore the relationship between freight rates of Liquified Natural Gas (LNG) and Liquified Petroleum Gas (LPG) carrier freight rates, and the global geopolitical risk, while also controlling for the macro environment. Our results show that a shock in geopolitical risk significantly increases the cost of the spot charter rates for both the LNG and LPG carriers, with the impact reaching around 25% for the former and 18% for the latter. Our results bare significant implications for the companies and countries involved in the liquefied gas trade, as it is likely to continue substituting other fossil fuels in the future. As such, the significance of a stable energy source makes it highly correlated with the economic development and energy security in the importing countries.

Geological and geotechnical review of gas and mudflow area as mitigation efforts in the risk of failure on Toll Road Project, Banten

The toll project in Banten shows that there is an area of gas burst at one of the locations. The embankment road passes through the gas burst. The geoelectric results that there is a silt/sandy soil layer and rock on the surface (10-20m), the second layer is soft silt to silt (20-40m), and then a rock layer. The second layer has gaps towards the first layer from the bottom layer, which is identified carrying gas and water, which is passed through the gaps to the surface. The seismic refraction also results that there are basins with gaps through the top and bottom of soil layers. The layer which indicates the gas and water carrier line is volcanic, sandy, forming a layer that has undergone deformation and partly a water-bearing layer (sand). The result of LEMIGAS explained that the gas bursts are also not methane that comes from the humus decomposition. The gas bursts are originated from depth and related to petroleum activity. The CO2 content is up to 97.87%, which is poisonous. However, the burst area is open, and the morphology is flat and does not form a cup, this gas spreads out so that the impact is not too pronounced.