bluuebunny/crossref_metadata_2025 huggingface dataset:
Heat losses in train movement in transportation tunnels in different operating conditions
Authors: Lugin IV , Alferova EL
Published: May 2021

The paper describes the results of numerical modeling of heat exchange between trains and air in transportation tunnels operated in the conditions of dry continental climate in Siberia and Russian Far East in cold seasons. The modeling uses a nonstationary 2D axially symmetrical formulation. The relationships have been obtained for the components of heat balance in transportation tunnels and the outside air temperature and the process conditions of operation of the tunnel entry equipment.
Experimental study of two-way hydraulic percussion device operation in vibro-impact drilling in rocks
Authors: Kudryavtsev VG
Published: May 2021

The authors describe the physical model of a hydraulic percussion device with frequency adjustment using standard flow rate controller and impact energy adjustment using an original throttle control of flow distribution, which allows dragging the hammering piston before its back run. The operating cycle characteristics required for the analysis of this system dynamics are obtained in a series of tests. Recommendations on improvement of operation of the hydraulic percussion device are given.
Modeling operation of sliding valve distribution in hydraulic percussion device with adjustable blow energy
Authors: Gorodilov LV , Pershin AI
Published: May 2021

The authors discuss the simulation model of a sliding valve distributor enabling adjustment of capabilities of hydraulic percussion devices. The paper presents the theoretical oscillograms of the valve characteristics and the plots of change in the valve mode versus the valve parameters.
Review of the placer mining methods with regard to geotechnical conditions and climate in Yakutia
Authors: Silin SA
Published: May 2021

The author reviews the current situation in opencast mining placers in Yakutia and characterizes geotechnical conditions and climate in the major mining regions in the Republic. In the most placers under mining, sands and peat have thickness of 1.5–1.6 and 5.2 m, respectively. Dozer cutting is applicable to peat with maximum thickness of 15.2 m; the combinations of dozer–shovel–dump truck and dozer–loader–dump truck are bet suitable t peat thicknesses f 17.5 and 11.5 m, respectively. Permafrost rocks are widely prepared to mining through natural thawing (71–76% in the Aldan, North and East regions). The common method of stripping is dozers. The most popular method of actual extraction is the combination of dozer–loader–dump truck. The most efficient approach to stripping is the combination of dozer–shovel–dump truck as its cost is lower than in striping with dozers or with the dozer– loader combination.
Rock slope stability assessment toward elimination of accidents
Authors: Zharikov SN , Taranzhin SS , Kutuev VA
Published: May 2021

The authors assess the effect of seismic vibrations induced by blasting in Biyanka gravel quarry and by movement of trains. The research was initiated in view of the accident in summer of 2017, which resulted in off-trip of two cars. The jointing structure of the rock slope is inspected, and the slope stability is assessed in some sites of the slope within the limits of the Asha railway haul. The recorded seismic vibrations in the rockfall-hazardous sites of the slope are less hazardous for the slope stability than the geological features of the slope, which are the cause of all rock falls. The recommendations on prevention of rock falls on the track are given.
Application of probabilistic clustering analysis to rockburst hazard assessment of rock mass
Authors: Gladyr AV , Tereshkin AA , Rasskazov MI , Konstantinov AV
Published: May 2021

The team of researchers from the Institute of Mining, FEB RAS have developed the rockburts hazards assessment procedure which enjoys successful application in Russian mines. The main objective of the procedure is the continuous computer-automated geomechanical monitoring of rock mass behavior, identification of seismically active zone and determination of static and dynamic parameters for rockburst hazard prediction and assessment in the detected zones. This paper co-authors propose an algorithm to identify fracture souse zones in rock mass and to calculate parameters of these zones by geomechanical monitoring data and using the methods and tools of nonparametric density estimate and probabilistic clustering analysis.
Provisions for higher mining efficiency with regard to cluster arrangement of mineral deposits
Authors: Batugina NS , Khoyutanov EA , Andreev YuP
Published: May 2021

Cluster (discrete) arrangement of minerals and their aggregates in different vectors in space is typical of most placers and deposits. Large and small pockets of valuable components in mineral bodies have different shapes, sizes, formation conditions and other geological characteristics. Cluster arrangement exists on all scales: an ore province in a region; an ore zone in an ore province; a deposit in an ore zone; an ore body in a deposit; an ore pillar in an ore body; pay zones in an ore pillar, nest, etc. By analogy with taxonomy and image identification, for differentiation of mineral resources by their processing properties or commercial value, space-detached accumulations of points representing some mineral objects are assumed as clusters with increased or lowered content of useful components. Structural order and clustering are the common features of many mineral deposits. Accurate geometrization of placers with regard to useful component content, inclusion of spatially variable quality conditions of useful components and proper management of mining favors reduction in volume of rock mass to be extracted, hauled and processed by 2 times at the same recovery factor of useful component; make it possible to increase cutoff grade by 2 times, and enables increment in production of useful component within the same production areas and at the same production capacities.
Microclimate normalization in working areas in oil mines
Authors: Klyuykin YuA , Semin MA
Published: May 2021

The paper discusses microclimate normalization methods applicable in oil mines, including air flow velocity variation, air sprinkling or cooling; installation of local blowing or drawing ventilation systems; arrangement of closed oil-bearing fluid harvesting system; heat-insulation lining; and integrated activities.
Investigation into the release of gravity-recoverable gold particles in products of a dynamic-impact mill
Authors: Lvov ES
Published: May 2021

The experimental data on assessment of the gravity-recoverable gold release in disintegration of lumpy gold-bearing geomaterials at dynamic-effect crushers DKD-300, designed at the Mineral Processing Laboratory at the Institute of Mining of the North, SB RAS, Yakutsk. The tests on gold-bearing ore originated from Gurbey deposit, made it possible to establish experimentally that the multiple-dynamic-effect facility enabled to release up to 47% gravity-recoverable gold of -1 mm in size.
Ventilation in long blind stopes during operation of load–haul–dumpers with combustion engines
Authors: Nakaryakov EV , Grishin EL
Published: May 2021

The paper describes the in-situ test data and mathematical modeling results on ventilation in long (more than 10 m) blind stopes during operation of load–haul–dumpers with combustion engines. The change in the toxic gas concentration versus the running time of the machinery in the stopes is determined, and the appropriate relations are derived.
Upgrading of qualitative characteristics of Yakutia brown coals
Authors: Popova KS
Published: May 2021

In Yakutia the fuel-and-energy balance involves low-grade brown coals originated from Kangalas, Kirov and Kempendyay deposits. The techniques to improve the efficiency of utilization and conservation of these coals involve classification of coals and burning of coarse-size products, enrichment, and briquetting of fine coal products. The last technique permits to upgrade the poor-grade coals of low demand and to produce the full-value fuel coal, convenient for transportation, long storage and effective combustion. The experimental results are given on the agglomeration of Kirov brown coal by briquetting with the introduction of polyethylene crumbs into the briquetting blend. This addition promotes 20 % increase in combustion heat as compared to this parameter for the original coal. The researchers propose the technological scheme for classification, preparation, follow-on briquetting of brown coals. The urgency of a local classification-and-briquetting plant is pointed out.
Mathematical modeling of heavy particle concentration in a jig bed
Authors: Sleptsova ES , Yakovlev BV
Published: May 2021

The mathematical model for motion of heavy particles surrounded with grains in a jig is proposed in the present paper. The grains are modeled by balls of a certain radius. The statistical approach to the process description is considered. The Brownian particle motion model is used, where the researchers consider and take into account the kinetic energy of grains surrounding the bead of a heavy particle moving under the influence and power of the vibrating jig, rather than the kinetic energy of the random thermal motion of the molecules bombarding the Brownian particle. This force depends on the amplitude and frequency, being, the parameters of the jigging cycles. The mathematical modeling allowed derivation of the Fokker-Planck-type equation for fractions distributed by density in the jig chamber. The dynamic curves for distribution of heavy grains along the height of a jig bed are obtained.
Fracture of quasi-brittle geomaterials with a circular hole under compression
Authors: Suknev SV
Published: May 2021

The new nonlocal fracture criteria are proposed, which are the extension of the average stress criterion and the point stress criterion, and which contain a complex parameter that characterizes the size of the fracture process zone and accounts not only for the material microstructure, but also ductile properties of the material, geometry of the specimen, and its loading conditions. The formulas are obtained for the critical pressure in the problem of tensile fracture initiation in the specimens of geomaterials containing a circular hole and subjected to uniformly or nonuniformly distributed compression. The results of the calculations are in good agreement with the experimental data on failure of gypsum plates with a hole.
Investigation into detonation properties of PS-2 ammonium-nitrate-based granulite of different producers
Authors: Flyagin AS , Menshikov PV , Taranzhin SS
Published: May 2021

The comparative test results on PS-2 granulite based on porous ammonium nitrate (PAN) manufactured under TU 7276-004-17131060-2008 of different producers: Sibirsky Delovoy Soyuz Co. (Kemerovo), Akron Co. (Belikiy Novgorod), OHK Uralkhim Co. (Berezniki), NAK Azot Co (Novomoskovsk) are reported in the paper. The relationship of PS-2 granulite detonation velocity in steel pipes of 108 mm in diameter versus the grade of ammonium nitrate used is justified experimentally. DATATRAP II DATA/VOD Recorder is employed in the present research work.
Geomechanical conditions of extraction of gold-bearing ore reserves under the bottom of an open pit mine in Malomyr quartz deposit
Authors: Potapchuk MI , Kryukov VG , Saksin BG , Tsoi DI
Published: May 2021

Based on the studies into the engineering geology, geodynamic zoning, geomechanical stability and stress–strain behavior of rock mass, the authors substantiate the mining technology for Malomyr Mine.
Processing of high-clayed fine-gold-bearing sands
Authors: Shirman GV , Matveev AI , Matveev IA , Ermeeva NG , Ochosov OYu
Published: May 2021

Under consideration are the main causes for the fine and very fine gold loss in processing the alluvial high-clayed sands at conventional equipment. Scrubber-free washing plant, consisting of disintegration, classification, steeply-inclined and centrifugal–vibration concentrators is presented. The experimental research results on the most-recent washing plant justified the economic feasibility of this application.
Disintegration of geomaterials in ore pretreatment–The role and significance
Authors: Matveev AI , Lvov ES
Published: May 2021

It is shown that all ore pretreatment processes including the stages of crushing and grinding, depending on the structural and texture features of geomaterials, have two interconnected sides: destruction and disintegration. Disintegration is considered as a process of selective separation of geomaterials by their weakest bonds and as a process concomitant with mechanical destruction. The paper justifies the methodology for determining the degree of geomaterial disintegration by the example of impact crushing using grain size composition of crushed products. The proposed procedure is based on isolating the fraction of material that is predominantly accumulated in the form of a mode, which depends on the energy of mechanical effect that is responsible for the process of actual geomaterial destruction and is determined as a lognormal distribution. In this case, the degree of disintegration is determined by subtracting the fraction of geomaterial formed directly by mechanical destruction (in percent or unit fractions) from total distribution sum of grain size composition. Examples of calculating the degree of disintegration for some ore geomaterials are given. Assessing the degree of disintegration according to the developed procedure can become an important characteristic of ore pretreatment and operating performance factor of crushing and grinding devices.
Justification of electromagnetic scanning of oil-filled formation using downhole matrix antenna arrays
Authors: Khmelinin AP , Konurin AI , Konurina MI
Published: May 2021

An overview of methods for mapping disturbances in a rock mass is given on the example of determining hydraulic fracture systems in an oil-filled formation. Methods of passive and active microseismic monitoring, as well as electromagnetic examining of rock masses for the presence of inhomogeneities in it are considered. A promising option for the development of hydraulic fracture mapping systems is proposed - creation of downhole logging probes representing ground penetrating radars that implement the mode of electrical scanning of the rock mass under study. The calculation of downhole antenna array based on the Butler matrix is performed. The calculated parameters of a phased antenna array with a Butler matrix can be used to design a downhole logging probe for mapping hydraulic fractures, as well as for surveying engineering structures, for example, foundations of buildings.
Influences of alternative diesel fuels on tailpipe emissions and particulate matter under the highway fuel economy test cycle
Authors: Boontatao Phanuwat , Chuepeng Sathaporn
Published: May 2021

Diesel engine vehicles are widely used worldwide in community and goods transport sectors due to their engine’s high efficiency and durability. Despite continuous improvements in various aspects, the combustion of compression ignition in conventional diesel engine is yet an important source of pollution and particulate matter that causes issues to human health and the environment. The objective of this research work is to study the use of conventional diesel (B7), biodiesel (B10) and premium diesel (DHi) fuels that affects to the release of exhaust gas and particulate matter emissions from tailpipes during a Highway Fuel Economy Test (HWFET) cycle. The experimental results have shown that the combustion of B7 and B10 reduced particulate matter by 0.38% and 51.0%, reduced total unburned hydrocarbon by 25.3% and 28.3%, reduced carbon monoxide by 43.3% and 64.0%, and reduced nitric oxide by 6.0% and 16.5%, respectively compared to DHi baseline on mass basis. The vehicle running on B10 releases a higher particle concentration with a smaller size compared to DHi.
Physical and chemical characteristics of carbonized corncob through hydrothermal and pyrolysis conversion
Authors: Srilek Nongnoot , Aggarangsi Pruk
Published: May 2021

Thailand and south-east Asia have been struggled with agriculture biomass residues management for decades where open burning causes severe air pollution affecting millions of people every year. Thermal carbonization is one of the most cost-effective and environmentally friendly techniques which converted the low value residues such as straw, corn stovers and corncob into a more valuable material such as solid biofuel, chemical adsorbent feed stocks. This study aims to explore crucial characteristics of carbonized corncob including fibre composition, BET surface area and FT-IR spectrums. The characteristics can be used to identify the potential of the material for further surface enhancement or surface activation to produce the bio-based activated carbon. The carbonization process in this work includes mild temperature hydrothermal technique and high-temperature pyrolysis process. The hydrothermal carbonization temperature is set at 250°C in a pressurized reactor where a pyrolysis is operated at 480°C and 380°C at atmospheric pressure. The BET surface area of “hydrochared” corncob derived from hydrothermal is 11.53 compared with 16.13 m2 g−1 of the raw materials. The pyrolized biochar at 480°C and 380°C yields surface area of 7.66 and 6.12 m2 g−1. The oxygenated functional groups on char surface and BET surface area are also compared to provide baseline for carbon activation.
Design of small wind turbines to produce electricity for low wind speed in Thailand
Authors: Panyawong Suradet , Manosroi Woradej
Published: May 2021

This work studied the design of small Vertical Axis Wind Turbine (VAWT) S Shape and Leaf Shape which are appropriate for low wind speed in Thailand. The theory of Overlaps Ratio (β), End Plates and Blade Areas which effect to wind turbines operation were analysed. The turbines were tested in a wind tunnel and connected to permanent magnet generator under wind speed conditions close to the real wind speed. The starting up wind speed and Power Coefficient of Leaf Shape were 0.81 m/s and 0.011 and the starting up wind speed and Power Coefficient of S Shape were 0.63 m/s and 0.038, respectively. The results showed that the S-Shape performance was better than Leaf Shape. The results from this study can be applied for developing and improving the small turbine for the application at the low wind speed area in Thailand
Results of the measurement of SOFC fuel cell stacks under pressure conditions
Authors: Berg H.P. , Dückershoff R. , Vorpahl M. , Himmelberg A.
Published: May 2021

Results from the measurement of SOFC fuel cell stacks under pressure conditions are presented. As part of a measurement campaign, the operation of a stack system is investigated, particularly under the operating conditions of a recuperated micro gas turbine. Above all, the performance and effectiveness of selected stack types at various operating pressures and operating temperatures are measured. With the test facility set up for such investigations, cell systems could be examined under atmospheric conditions and with pressures of up to 5 bar.

It is shown that in operating conditions under pressure, the output of the fuel cell systems are improving. From a gauge pressure of 4 bar, the performance curve is flattened and higher pressures only produced a marginal increase in performance. Furthermore, the cells tested at overpressure show a steady-state behavior more quickly under load change requirements than in atmospheric operation. This means that more flexible operating modes with faster response behavior can be realized. By choosing a suitable operating temperature, the efficiency of the system is further increasing. Care was taken to select the operating conditions of the cell systems so that coking can be prevented.

Finally, a statement can be made about the pressure dependence of the fuel conversion rate. Parasitic reactions at the anode can be related to the power output. The tests carried out have shown that the high-temperature fuel cell is a promising service provider of the future. A combination of SOFC high-temperature fuel cells and micro gas turbines in one machine could, in addition to the internal provision of the required pressure, also lead to better dynamics of the entire system and increase the energy yield from the primary energy source.
Takeoff Performance Analysis of a Light Amphibious Airplane
Authors: Chinvorarat Sinchai , Watjatrakul Boonchai , Nimdum Pongsak , Sangpet Teerawat , Vallikul Pumyos
Published: May 2021

The performance analysis of a light amphibious airplane during takeoff from the water surface has been presented in this paper. The airplane is one of the light amphibious airplane series built in Thailand with a bi-wing configuration. The conceptual design aims to build a short takeoff and landing (STOL) amphibious airplane. The mathematical model cooperated with several complicated parameters is presented and solved by MATLAB. The water-drag resistance of the airplane is estimated from typical seaplane hull NASA technical information, which enhances the correctness of the model at takeoff configuration. The simulation reveals that the seaplane can successfully takeoff from calm water in 24.5 seconds at the speed of 54 KCAS and an approximate distance of 890 feet with the AOA of 10 degrees.
Investigation of loose contact oxidation kinetic analysis on diesel particulate filter’s wall surface using non-isothermal TGA technique
Authors: Zin Win Swe , Karin Preechar , Phairote Watanyoo , Chollacoop Nuwong , Saisirirat Peerawat , Hanamura Katsunori
Published: May 2021

Carbonaceous soot particles emitted from diesel engines are dangerous to human health because of its carcinogenic activity and can penetrate into lungs. In order to control soot emissions, diesel particulate filters (DPFs) are widely used to meet progessively stringent regulations of vehicle emissions limits. In this article, the characterization of conventional DPF microstructure was briefly investigated by scanning electron microscopy (SEM) addition with energy dispersive X-ray analysis (EDX) and X-ray fluorescence analysis (XRF). Non-isothermal oxidation mechanism of soot on conventional DPF was carried out from thermogravimetric analysis (TGA) under air atmosphere with the flow rate of 40ml/min at the heating rates of 5, 10, and 15°C/min. The kinetic parameters were calculated by three non-isothermal model-free methods. The average value of apparent activation energy obtained by Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Kissinger (K) were 77.02, 65.29 and 70.48 kJ/mol, respectively at different heating rates. The average results got from this work indicate that non-isothermal experiments were quite low compared to kinetics parameters estimated by the isothermal method from previous research.
Three-dimensional effects on the performance of multi-level overtopping wave energy converter
Authors: Jungrungruengtaworn S. , Thaweewat N. , Hyun B.S.
Published: May 2021

The performance of a multi-level overtopping wave energy converter has been numerically investigated in a three-dimensional wave tank. The device has three extra slots and is positioned on a breakwater. The span length of the breakwater is the main parameter associated with the three-dimensional effects on the hydraulic efficiency of the wave energy device. It has been shown that the device with a finite span yields a lower captured crest energy due to waves falling-down the edges during the run-up process. The result also implies that as the span of the device is increased, the efficiency tends to increase further to resemble the two-dimensional device. The three-dimensional mechanism has a significant influence on the potential energy in the water being stored by the higher reservoirs, while that of lower ones have relatively smaller effects. In addition, a relation between hydraulic efficiencies of two and three-dimensional devices has been proposed.
Effect of feed sprue size on porosity defects in Platinum 950 centrifugal investment casting via numerical modelling
Authors: Munpakdee K. , Ninpetch P. , Otarawanna S. , Canyook R. , Kowitwarangkul P.
Published: May 2021

The centrifugal investment casting process is typically used in the jewelry manufacturing industry. However, porosity defects are often found in jewelry castings made by this process. Porosity on the casting surface is a major concern for jewelry manufacturers as the defect leads to significant yield losses during the repair work. Improper feed sprue design is one of the major causes of porosity defects. The purpose of this work is to study the effect of feed sprue size on porosity defects in Platinum 950 jewelry made by the centrifugal investment casting process. Two feed sprue sizes were experimented in this study. FLOW-3D CAST software was employed for the casting process simulation. Simulation results were analysed together with experimental results quantified by an image analysis technique. The results show that the larger feed sprue provides castings with less porosity compared to the smaller feed sprue.
Steel fiber/polyethylene terephtalate composites
Authors: Duekhodthod Rossarin , Kitkamthorn Usanee , Mitsomwang Pusit , Intaing Tawatchai , Borrisutthekul Rattana
Published: May 2021

Currently, lightweight materials with high performance have been strongly needed to meet the requirements of advanced structural materials. One of the promising lightweight materials is the metals fiber reinforced plastic composite, which usually gives good specific strength and high toughness. However, de-bonding between metal fiber and plastic is the main problem in the production and utilization of the composite. Recently, Katayama, et., al. studied the dissimilar materials joining between plastics and metals such as PET/SUS 304 and so on. The joint was succeeded with the reaction between the metal oxide and functional group in the molecule of the polymer. The possibility to join metal/plastic may provide the new approach to produce new design composites. Thus, the objective of the study is to investigate the feasibility to produce stainless steel fiber reinforced PET plastics composite (SFRP). In experiments, stainless steel mesh and PET sheet with 0.5 mm of thickness were used as materials to fabricate the SFRP composite. The hot pressing of sandwich stacks with inserted SUS304 wire mesh between two PET sheets was performed at 120°C. Results indicated that high strength composite without de-bonding could be obtained.
Sintered 316L/Cu/h-BN composites
Authors: Chusong E. , Kansuwan P. , Khosakul R. , Ohtake N. , Wila P. , Tosangthum N. , Vetayanugul B. , Tongsri R.
Published: May 2021

Sintered 316L/h-BN composites show high potential as self-lubricating materials, which can be applied as moving parts where lube oils and greases are not applicable and inaccessible for maintenance. The past production of such composites by sintering, faced two problems. Firstly - interaction between 316L matrix and h-BN resulting in loss of h-BN content and its lubricity. And secondly - poor 316L matrix integrity. This work employed two approaches to solve such problems. The first approach was the use of nitrogen-containing atmosphere for sintering, to retard 316L matrix and h-BN interaction. And the second approach, was copper addition to promote sintering of 316L powder particles. Sintered self-lubricating 316L/Cu/h-BN composites were produced from mixtures of 3 different 316L/Cu matrices (made by additions of 2.0, 4.0 and 6.0 wt.% copper powder to 316L powder) and 15 vol.% of h-BN powder. Green compacts of powder mixtures were sintered under cracked ammonia (75 vol.% hydrogen + 25 vol. % nitrogen) at 1300°C for 60 minutes. The sintered composites were cooled in a Linn high temperature sintering furnace. It was found that copper additions led to the decrease of densities of sintered 316L/Cu/h-BN composites, compared to that of sintered 316L/h-BN composite, due to porosity left behind by copper powder melting and dissolution. Tensile strengths of sintered 316L/Cu/h-BN composites were improved when copper contents were 4 and 6 wt.%. There was no intergranular phase, the evidence of 316L matrix and h-BN interaction in all experimental sintered composites. Microstructural observation by scanning electron microscopy (SEM) also revealed that h-BN flakes still existed in pores of sintered composites. The unreacted h-BN flakes are expected to provide lubricity of sintered composites.
Effects of the environment on thermo physiological responses via 3D human eye model with porous media heat transfer theory under inconstant solar irradiation
Authors: Chawengwanicha P. , Rattanadecho P. , Keangin P.
Published: May 2021

The human eye is one of the most sensitive parts of our entire body. The lens is an important component of the eye, and it also plays an important role in vision. A lens has a normal temperature below 38.5°C. Thermal effects with solar irradiation result in the temperature of the lens to increase to more than 38.5 °C and may significantly influence the thermal physiologic response which, in turn, will cause the of deterioration of the lens. Therefore, investigation to get knowledge and guidelines to avoid thermal effects from the environment with solar irradiation, will help prevent the eyes from deterioration. However, the study of invasion, within the human body is impracticable. The study of environmental effects on thermo physiological responses within the human eye, from numerical analysis, is another alternative that is gaining attention worldwide. The purpose of this research is to learn about thermal physiologic response on human eyes exposed to solar irradiation, using the three-dimensional (3D) model by finite element method (FEM) via a computer program. This study uses the heat transfer equation and the Navier-Stroke equation to describe heat transfer phenomena in porous mediums and fluid flow phenomena within the 3D human eye model, based on considering the natural convection heat transfer of aqueous humor and vitreous humor, under inconstant solar irradiation. The effects of the environmental parameters such as ambient temperature and air convection heat transfer coefficient are investigated. The results show that the case study which makes the best cooling mechanism is the effect of ambient temperature with ambient temperature at 25°C and effect of air convection heat transfer coefficient at 40 W/m2·K that the eye can absorb maximum solar irradiance at 575 W/m2 at the lens reaches 38.5°C and the worst cooling mechanism is the effect of ambient temperature with ambient temperature at 35°C that the eye can absorb maximum solar irradiance at 360 W/m2 at the lens reaches 38.5°C. The results from this study provide the essential aspects for a fundamental understanding of thermal physiologic response within human eye subjected to solar irradiation.
Assessment of turbulence models for low turbulent natural convection heat transfer in rectangular enclosed cavity using OpenFOAM
Authors: Loksupapaiboon Kittipos , Suvanjumrat Chakrit
Published: May 2021

This research aimed to study two-equation turbulence models, for the simulation of low turbulent natural convection heat transfer, which happened in a rectangular enclosure. These models include k–ɛ, k–ω, RNG k–ɛ, k–ω SST and Realizable k–ɛ which are two-equation turbulence models in OpenFOAM. The simulation was carried out to compare against experiment in literatures which gave a Rayleigh number (Ra) of 1.58×109. The 3D cell structure by the 50×50×100 cells for the rectangular enclosure dimensions of 0.75 m (width)×0.75 m (height)×1.50 m (length) was modeled. It gave the large y+ of 30 but was still in the initial sub-layer. It was found that the k–ω model provided the best prediction of turbulent natural convection heat transfer. The standard k and ω wall functions were carried out to simulate well with the k–ω model. It was good modeling technique which the fine cells were not necessary to define nearly enclosure walls.
Numerical simulation of flow over a passive disturbance and backward-facing step
Authors: Loksupapaiboon Kittipos , Suvanjumrat Chakrit
Published: May 2021

This research aimed to simulate the flow past a rib and backward-facing step (BFS). The Reynolds and sub-grid-scale (SGS) stresses were modelled. These models consisted of k–ɛ, Smagorinksy-Lilly, SGS turbulence kinetic energy (kSGS
), dynamic SGS and wall-adapting local eddy-viscosity (WALE) which implemented in Open FOAM. The simulation was carried out to compare against the experiment in literatures which gave a high Reynolds number of 15,500. The simulation results showed that the k–ɛ model provided the best prediction of the turbulent flow over a passive disturbance and BFS. The absence of rib was carried out to compare with the presence of the rib. It was found that the rib positions had affected to flow reattachment behind the BFS.
Effect of interference on the press fitting of railway wheel and axle assemblies
Authors: Nwe Theingi , Pimsarn Monsak
Published: May 2021

Press fitting is one of the common fastening methods used to assemble mechanical components. It has also received considerable critical many industrial applications, for example, railway wheel and axle are usually assembled by press-fitting. This process generates high stress on the axle-fillet area and fatigue is generally initiated due to the stress concentration. This paper attempts to propose the stress distribution and deformation of a railway axle. Various interference clearances were analyzed using finite element method. The contact pressure at the axle wheel seat along the axial direction was examined as it significantly influences the press-fitted components life. The analytical results from Lame’s theory [1] were compared with finite element analysis results for the wheel and axle press-fitting process. The results obtained from both methods were in good agreement and the maximum relative error of the contact pressure is by 11.08 %. Additionally, the results show that the Von-Mises stresses on the axle wheel seat and fillet areas were found to be increased if the interference increased.
Potentials of the direct use of ethanol fuel cell as backup electricity for renewable energy system
Authors: Saisirirat Penyarat , Saisirirat Peerawat , Kongdai Papopchote , Joommanee Brodindech
Published: May 2021

The issue of renewable energy has received considerable critical attention. This has led to a decline in the population of Greenhouse Gas (henceforth GHG) emissions, health-risk related emissions and energy security. The main challenge faced by many researchers is major issues of low reliability for producing electricity from solar PV. Wind energy has accentuated the problem of sharing of these renewable energies down in the National Energy plans. The solar PV and wind energy may cause fluctuation depending on the daytime and season. The backup electricity is required for increasing reliability of these renewable energy sources. It is now well established that the Direct Ethanol Fuel Cell (henceforth DEFC) is a high bio-fuel production country. Ethanol also has many advantages such as, high energy density, easy for storage and transport, less dangerous to handle compared to hydrogen gas. In addition, the energy efficiency of DEFC is comparable to that of other fuel cell technology. The low operating temperature means less startup period and thermal input energy. This study aims to analyze the potentials to use DEFC as backup electricity for the renewable energy system. The performance characteristics were examined according to updated experimental results. The advantages and challenges were also discussed in this study.
A Mathematical Model of Laser Drilling with Laser Absorption in the Plasma
Authors: Suchatawat M
Published: May 2021

Despite being an accurate process with high processing speed, laser drilling suffers from several drawbacks including wall taper, recast layer and spatter. Hence, in order to improve the process efficiency and achieve the good hole quality, it is crucial to have a precise model which can be used as a tool to relate the process parameters to the process output. In this paper, an analytical model of laser drilling is developed. The governing equations are established from the energy equations at the solid-liquid and liquid-vapor interfaces. Absorption of laser energy in the plasma and an additional energy generated from the exothermic reaction are also included in the model. Aiming at simplifying the model, a constant value of the plasma absorption coefficient of the laser beam is employed. Validation of the model is done by comparing with the available experimental data. It is concluded that the recommended value of the plasma absorption coefficient for low carbon steel drilling is 0.2.
Group-velocity symmetry in photonic crystal fibre for ultra-tunable quantum frequency conversion
Authors: Parry C , Main P B , Wright T A , Mosley P J
Published: May 2021

Low-noise frequency conversion of single photons is a critical tool in establishing fibre-based quantum networks. We show that a single photonic crystal fibre can achieve frequency conversion by Bragg-scattering four-wave mixing of source photons from an ultra-broad wavelength range by engineering a symmetric group velocity profile. Furthermore, we discuss how pump tuning can mitigate realistic discrepancies in device fabrication. This enables a single highly adaptable frequency conversion interface to link disparate nodes in a quantum network via the telecoms band.
DevOmics: an integrated multi-omics database of human and mouse early embryo
Authors: Yan Zhiqiang , An Jianting , Peng Yong , Kong Siming , Liu Qiang , Yang Ming , He Qilong , Song Shi , Chen Yidong , Chen Wei , Li Rong , Qiao Jie , Yan Liying
Published: May 2021

Transcriptomic and epigenetic alterations during early embryo development have been proven to play essential roles in regulating the cell fate. Nowadays, advances in single-cell transcriptomics and epigenomics profiling techniques provide large volumes of data for understanding the molecular regulatory mechanisms in early embryos and facilitate the investigation of assisted reproductive technology as well as preimplantation genetic testing. However, the lack of integrated data collection and unified analytic procedures greatly limits their usage in scientific research and clinical application. Hence, it is necessary to establish a database integrating the regulatory information of human and mouse early embryos with unified analytic procedures. Here, we introduce DevOmics (http://devomics.cn/), which contains normalized gene expression, DNA methylation, histone modifications (H3K4me3, H3K9me3, H3K27me3, H3K27ac), chromatin accessibility and 3D chromatin architecture profiles of human and mouse early embryos spanning six developmental stages (zygote, 2cell, 4cell, 8cell, morula and blastocyst (ICM, TE)). The current version of DevOmics provides Search and Advanced Search for retrieving genes a researcher is interested in, Analysis Tools including the differentially expressed genes (DEGs) analysis for acquiring DEGs between different types of samples, allelic explorer for displaying allele-specific gene expression as well as epigenetic modifications and correlation analysis for showing the dynamic changes in different layers of data across developmental stages, as well as Genome Browser and Ortholog for visualization. DevOmics offers a user-friendly website for biologists and clinicians to decipher molecular regulatory mechanisms of human and mouse early embryos.
NICEpath: Finding metabolic pathways in large networks through atom-conserving substrate–product pairs
Authors: Hafner Jasmin , Hatzimanikatis Vassily
Published: May 2021

Motivation

Finding biosynthetic pathways is essential for metabolic engineering of organisms to produce chemicals, biodegradation prediction of pollutants and drugs, and for the elucidation of bioproduction pathways of secondary metabolites. A key step in biosynthetic pathway design is the extraction of novel metabolic pathways from big networks that integrate known biological, as well as novel, predicted biotransformations. However, the efficient analysis and the navigation of big biochemical networks remain a challenge.

Results

Here, we propose the construction of searchable graph representations of metabolic networks. Each reaction is decomposed into pairs of reactants and products, and each pair is assigned a weight, which is calculated from the number of conserved atoms between the reactant and the product molecule. We test our method on a biochemical network that spans 6546 known enzymatic reactions to show how our approach elegantly extracts biologically relevant metabolic pathways from biochemical networks, and how the proposed network structure enables the application of efficient graph search algorithms that improve navigation and pathway identification in big metabolic networks. The weighted reactant–product pairs of an example network and the corresponding graph search algorithm are available online. The proposed method extracts metabolic pathways fast and reliably from big biochemical networks, which is inherently important for all applications involving the engineering of metabolic networks.

Availability and implementation

https://github.com/EPFL-LCSB/nicepath.

Supplementary information

Supplementary data are available at Bioinformatics online.
A Multidimensional Approach to Explore the Experiences with Ethnic Matching amongst Chinese Social Service Practitioners in the Greater Toronto Area
Authors: Leung Vivian W Y , Tan Weijia , Chuang Deng-Min , Tsang Ka Tat , Lai Daniel W L
Published: May 2021

In multicultural societies, social workers often work with people of diverse cultural backgrounds. As one of the strategies to facilitate social workers’ cultural competence in diverse settings, they are often matched with clients of the same or similar cultural backgrounds. This practice is called ethnic matching and is commonly utilised in ethno-specific and immigrant-serving organisations. This practice has been extensively studied in the literature and is believed to be beneficial to treatment acceptability and service quality. Nonetheless, most of the existing literature focuses on the practitioner–client dyad without taking the broader context into consideration. This study adopted a multidimensional cultural competence approach to examine Chinese practitioners’ lived experiences of serving Chinese immigrants in the Greater Toronto Area (GTA). Six focus groups were conducted (n = 34), and data were analysed using a grounded theory approach. Results show themes across four levels: (i) personal: personal experience as a motivator; (ii) interpersonal: shared culture and language as a double-edged sword; (iii) organisational: service target shifts and increased difficulty to ethnically match and (iv) community: intracommunity heterogeneity and mismatch. This study provides recommendations for social workers, educators and policymakers to consider when applying ethnic matching in cross-cultural settings.
Toward Both Privacy and Efficiency of Homomorphic MACs for Polynomial Functions and Its Applications
Authors: Li Shimin , Wang Xin , Xue Rui
Published: May 2021

Homomorphic message authentication codes (MACs) allow a user to outsource data to an untrusted server and verify the correctness of returned computation results over the outsourced data. Many cloud applications need delegation computations over outsourced data with dual capabilities. On one hand, they need to keep the outsourced data secret such that the server cannot trace and infer any sensitive information from the computation results. On the other hand, the user should be able to efficiently verify the computation results. Unfortunately, the state-of-the-art homomorphic MAC schemes are not so desirable due to either poor privacy or low verification efficiency. In this paper, we first put forward a new cryptographic primitive called privacy-preserving homomorphic MACs (PHMAC) that simultaneously provides data privacy and efficient verification. Then, we present a PHMAC construction capable for the evaluation of polynomials of fixed degree $d\geq 1$, in which the tag does not reveal any information of underlying authenticated data while being verifiable in constant time (in an amortized sense). As an application, we give a generic construction of homomorphic authenticated encryption (HAE) from proposed PHMAC and homomorphic encryption. Benefited from the functionalities of underlying PHMAC scheme, the derived HAE enjoys stronger authenticity and supports larger classes of functions than that of Lai et al. (Verifiable Computation on Outsourced Encrypted Data. In Computer Security—ESORICS 2014—19th European Symposium on Research in Computer Security, Wroclaw, Poland, September 7–11, Part I, pp. 273–291. Springer, Berlin). Such HAE enables verifiable delegation computations over growing outsourced encrypted data in an efficient way.
Stakeholders’ perspectives on online interventions to improve mental health in eating disorder patients and carers in Germany
Authors: Schmidt-Hantke Juliane , Vollert Bianka , Hagner Franziska , Beintner Ina , Hütter Kristian , Nitsch Martina , Jacobi Corinna , Waldherr Karin
Published: May 2021

Background

Eating disorders are causing severe consequences for those affected as well as a high burden for their carers. Although there is a substantial need for psychological assistance, different factors are hindering access to support. Internet-based interventions can help to overcome these barriers. To date, there is only little knowledge on attitudes of potential users, facilitators (e.g. psychologists) and decision makers (e.g. health insurances) regarding these interventions.

Methods

We conducted focus groups with potential users (N = 30) and semi-structured interviews with potential decision makers (N = 4). Potential facilitators (N = 41) participated in an online survey. Stakeholders’ experiences, attitudes, and their needs regarding Internet-based interventions for eating disorder patients and carers were assessed. Furthermore, hindering and fostering factors related to reach, adoption, implementation and maintenance were analyzed.

Results

About two-thirds of the participating facilitators have heard or read about Internet-based interventions in general. In contrast, the other stakeholders mentioned to have no or little experience with such interventions. Factors like anonymity, availability and cost-effectiveness were seen as major advantages. Also disadvantages, e.g. lack of personal contact, limitations by disease severity and concerns on data safety, were mentioned. Stakeholders stated the need for interventions which are usable, evidence-based, tailored and provide personal support.

Conclusion

Stakeholders considered Internet-based programmes to have more advantages than disadvantages. Effort should be put in providing systematic education to address prejudices. When offering an online intervention, stakeholders’ needs, as well as a continuous evaluation and adaptation, have to be taken into account.