Permanent-magnet synchronous machines (PMSMs) are widely used in electric vehicles owing to many advantages, such as high power density, high efficiency, etc. Iron losses can account for a significant component of the total loss in permanent-magnet (PM) machines. Consequently, these losses should be carefully considered during the PMSM design. In this paper, an analytical calculation method has been proposed to predict the magnetic field distribution and stator iron losses in the surface-mounted permanent magnet (SPM) synchronous machines. The method introduces the notion of complex relative air-gap permeance to take into account the effect of slotting. The imaginary part of the relative air-gap permeance is neglected to simplify the calculation of the magnetic field distribution in the slotted air gap for the surface-mounted permanent-magnet (SPM) machine. Based on the armature reaction magnetic field analysis, the stator iron losses can be estimated by the modified Steinmetz equation... [more]

In ASP (Alkali-Surfactant-Polymer) flooding processes, surfactants help to enhance oil recovery by lowering the interfacial tension between the oil and water. However, due to the high cost of surfactants and the stability of the emulsion that varies with surfactant concentration, it is necessary to optimize the surfactant concentration in ASP flooding. In this study, we combined numerical simulation and physical experimental research to solve this problem. In order to screen for the optimal surfactant concentration in the main and vice slugs, CMG (Computer Measurement Group) numerical simulation software was used to change the surfactant concentration in the injected compound system and the oil recovery factor and the recovery percent of reserves were compared. The physical experiments were also carried out with different surfactant concentrations and the results verified the simulation results. It shows that the recovery factor increases with the surfactant concentration. The optimal... [more]

To investigate the deformation-failure process of Longmaxi shale under uniaxial compression conditions from the mesoscopic and macroscopic points of view, novel X-ray microComputed Tomography (micro-CT) equipment combined with unique loading apparatus was used. Cylindrical shale samples (4 mm in diameter and 8 mm in height) were produced to perform a series of uniaxial compression tests. CT scanning images at different time points during the loading process were obtained to study the characteristics of the progressive failure. In addition, stereograms were reconstructed and vertical slices were selected to explain the failure mechanism. From the results of the testing the low-density area, local per-peak cracks, numerous post-peak cracks and secondary cracks consecutively appeared in the CT images. Vertical and inclined fissures in the samples could be observed from the stereograms’ surfaces and from internal slices. The cracking indicates that the failure process of shale is progressi... [more]

In this paper, a novel isolated bidirectional DC-DC converter is proposed, which is able to accomplish high step-up/down voltage conversion. Therefore, it is suitable for hybrid electric vehicle, fuel cell vehicle, energy backup system, and grid-system applications. The proposed converter incorporates a coupled inductor to behave forward-and-flyback energy conversion for high voltage ratio and provide galvanic isolation. The energy stored in the leakage inductor of the coupled inductor can be recycled without the use of additional snubber mechanism or clamped circuit. No matter in step-up or step-down mode, all power switches can operate with soft switching. Moreover, there is a inherit feature that metal⁻oxide⁻semiconductor field-effect transistors (MOSFETs) with smaller on-state resistance can be adopted because of lower voltage endurance at primary side. Operation principle, voltage ratio derivation, and inductor design are thoroughly described in this paper. In addition, a 1-kW pro... [more]

Low pressure, low permeability, and low saturation of Chinese coal-bed methane (CBM) reservoirs make underbalanced drilling (UBD) widely used for mining CBM in China. In this study, mechanical behavior and permeability of coal rock were investigated under different degrees of unloading confining pressure (UCP)-reloading axial stress (RAS) by a triaxial experimental apparatus. These tests revealed that: (1) peak deviatoric stress of coal rock in UCP-RAS is lower than that in a conventional triaxial compression (CTC) test, and the peak deviatoric stress linearly relates the degree of unloading confining pressure. The deformation modulus of coal in UCP-RAS is lower than that in CTC, while the lateral expansion ratio is larger than that in CTC; (2) higher UCP leads to a faster increase of permeability during RAS until the failure of coal; (3) the cohesion and internal friction angle tested by UCP-RAS are lower by 4.57% and 15.18% than those tested by CTC. In addition, a field case (Zhaozhu... [more]

To explore the influence of tip clearance on pressure fluctuation in a low specific speed mixed-flow pump, tip clearances δ of 0.25 mm, 0.75 mm and 1.00 mm, along with no tip clearance, were selected. The reliability of the simulation was verified by comparison with the experimental data of external characteristics and fluctuation in the guide vane passage. Through ANSYS-CFX, MATLAB code and fast Fourier transform (FFT) algorithm, pressure fluctuation characteristics in this pump were obtained. The results show that pressure fluctuation exists in all conditions due to the rotor-stator interaction. Under the no tip clearance and tip clearance conditions, the maximum fluctuation value was located near the guide inlet and impeller outlet, respectively. Clearance leakage had less influence on pressure fluctuation at the impeller inlet and central regions within a certain range of the clearance; beyond this range, fluctuations in the whole flow passage increased significantly, while the cle... [more]

In most cases, arsenic is an unfavorable element in metallurgical processes. The mechanism of arsenic removal was investigated through roasting experiments performed on arsenopyrite-bearing iron ore. Thermodynamic calculation of arsenic recovery was carried out by FactSage 7.0 software (Thermfact/CRCT, Montreal, Canada; GTT-Technologies, Ahern, Germany). Moreover, the arsenic residues in dust ash were recovered by roasting dust ash in a reducing atmosphere. Furthermore, the corresponding chemical properties of the roasted ore and dust ash were determined by X-ray diffraction, inductively coupled plasma atomic emission spectrometry, and scanning electron microscopy, coupled with energy-dispersive X-ray spectroscopy. The experimental results revealed that the arsenic in arsenopyrite-bearing iron ore can be removed in the form of As2O3(g) in an air or nitrogen atmosphere by a roasting method. The efficiency of arsenic removal through roasting in air was found to be less than that in nitro... [more]

This research experimentally analyzed the impacts of various water cement (W/C) ratios of ultrafine cement grout material and normal loads FN applied to fractures on grout nonlinear flow behavior through a rough plexiglass fractured sample. An effective self-made apparatus was designed and manufactured to conduct the stress-dependent grout flow tests on the plexiglass sample containing rough fractures. At each W/C ratio, the grout pressure P increased from 0 to 0.9 MPa, and the normal loads FN ranged from 666.3 to 1467.8 N. The results of the experiments indicate that (1) the Forchheimer’s law can be used to express the results of grout nonlinear flow through rough fractures. Moreover, both nonlinear coefficient a and linear coefficient b in Forchheimer’s law decreased with the increase of the W/C ratio, but increased with the increase of the FN value. (2) For normalized transmissivity, with the increase of Re, the decline of the T/T0−Re curves means that the grout flow behavior throug... [more]

In metallurgical and chemical engineering processes, the gas−liquid−liquid multiphase flow phenomenon is often encountered. The movement of bubbles in the liquid, and the influence of bubbles on the liquid−liquid interface, have been the focus of extensive research. In the present work, an air−water−oil system was used to explore the movement of bubbles and the phenomenon that occurs when bubbles pass through an interface with various oil viscosities at various gas flow rates. The results show that bubble movement is greatly influenced by the viscosity of the oil at low gas flow rates. The type of phase entrainment and the jet height was changed when increasing the gas flow rate. The stability of the water−oil interface was enhanced with increasing viscosity of the oil phase.

The aim of this study is to model the hydrodynamic processes of the Istanbul Strait with its stratified flow characteristics, and calibrate the most important parameters using local and global search algorithms. For that, two open boundary conditions are defined, which are in the northern and southern parts of the Strait. Observed bathymetric, hydrographic, meteorological, and water-level data are used to set up the Delft3D-FLOW model. First, the sensitivities of the model parameters on the numerical model outputs are assessed using Parameter EStimation Tool (PEST) toolbox. Then, the model is calibrated based on the objective functions, focusing on the flow rates of the upper and lower layers. The salinity and temperature profiles of the strait are only used for model validation. The results show that the calibrated model outputs of the Istanbul Strait are reliable and consistent with the in situ measurements. The sensitivity analysis reveals that the spatial low-pass filter coefficien... [more]

Water inrush of tunnel face is one of the most common geological disasters during tunnel construction in China. Aiming at the rock mass with multi fractures in water-resistant strata ahead of karst tunnel, the compressive-shear cracking property is analyzed by fracture mechanics theory and the change law of rock bridge shear strength with branch crack propagated length under karst water pressure and geo-stress is studied according to Mohr-Coulomb strength criterion. Moreover, the critical water pressure of water-resistant strata with multi fractures under tension-shear failure is deduced. The safe thickness of water-resistant strata with multi fractures ahead of karst tunnel is established based on two band theory and critical water pressure, and the influence of karst water pressure, initial crack length, crack spacing, array pitch of cracks, lateral pressure coefficient and the angle between the crack and the maximum principal stress on the minimum safe thickness of water-resistant s... [more]

The blast furnace iron making process (BFIMP) is the key of the integrated steel enterprise for energy saving due to its largest energy consumption proportion. In this paper, an all-factors analysis approach on energy consumption was proposed in BFIMP. Firstly, the BFIMP composition and production data should be collected. Secondly, the material flows and energy flows analysis models could be established based on material balance and the thermal equilibrium. Then, the all influence factors (mainly including material flows, energy flows and operation parameters) on energy consumption were obtained. Thirdly, the main influence factors, which influenced the coke ratio (CR) and the pulverized coal injection ratio (PCIR), were obtained by using the partial correlation analysis (PCA) method, because CR and PCIR were the key energy consumption performance in BFIMP. Furthermore, anall-factors analysis result could be achieved by a multivariate linear model (MLR), which was established through... [more]

In order to explore the distribution law of stress field under the mining mode of gob-side entry retaining by roof cutting without pillar (GERRCP) under goaf, based on the engineering background of 8102 and 9101 working faces in Xiashanmao coal mine, the stress field distribution of GERRCP and traditional remaining pillar was studied by means of theoretical analysis and numerical simulation. The simulation results showed that: (1) in the front of the working face, the vertical peak stress of non-pillar mining was smaller than that of the remaining pillar mining, and it could effectively control stress concentration in surrounding rock of the mining roadway; the trend of horizontal stress distribution of the two was the same, and the area, span and peak stress of stress the rise zone were the largest in large pillar mining and the minimum in non-pillar mining. (2) On the left side of the working face, the vertical stress presented increasing-decreasing characteristics under non-pillar m... [more]

This is the LAPSE stakeholder report for 2019, including news, interesting statistics, new features, and the plan for the next year.

Dette er det LAPSE interessenter rapport for 2019, inkludert nyheter, interessant statistikk, nye funksjoner, og planen for neste år.

The remediation of beaches contaminated with oil includes the application of surfactants and/or the application of amendments to enhance oil biodegradation (i.e., bioremediation). This study focused on evaluating the practicability of the high pressure injection (HPI) of dissolved chemicals into the subsurface of a lentic Alaskan beach subjected to a 5 m tidal range. A conservative tracer, lithium, in a lithium bromide (LiBr) solution, was injected into the beach at 1.0 m depth near the mid-tide line. The flow rate was varied between 1.0 and 1.5 L/min, and the resulting injection pressure varied between 3 m and 6 m of water. The concentration of the injected tracer was measured from four surrounding monitoring wells at multiple depths. The HPI associated with a flow rate of 1.5 L/min resulted in a Darcy flux in the cross-shore direction at 1.15 × 10−5 m/s compared to that of 7.5 × 10−6 m/s under normal conditions. The HPI, thus, enhanced the hydraulic conveyance of the beach. The resul... [more]

Experiments have shown that a suspension of particles of different dimensions pushed through a periodic lattice of micrometric obstacles can be sorted based on particle size. This label-free separation mechanism, referred to as Deterministic Lateral Displacement (DLD), has been explained hinging on the structure of the 2D solution of the Stokes flow through the patterned geometry, thus neglecting the influence of the no-slip conditions at the top and bottom walls of the channel hosting the obstacle lattice. We show that the no-slip conditions at these surfaces trigger the onset of off-plane velocity components, which impart full three-dimensional character to the flow. The impact of the 3D flow structure on particle transport is investigated by enforcing an excluded volume approach for modelling the interaction between the finite-sized particles and the solid surfaces. We find that the combined action of particle diffusion and of the off-plane velocity component causes the suspended pa... [more]

We have become aware that figures, tables, experimental data, and a whole paragraph in the results and discussion section of the published article [...]

The use of renewable resources for polymer production is receiving substantial and ever-growing interest [...]

This work presents a numerical investigation of viscous nanofluid flow over a curved stretching surface. Single-walled carbon nanotubes were taken as a solid constituent of the nanofluids. Dynamic viscosity was assumed to be an inverse function of fluid temperature. The problem is modeled with the help of a generalized theory of Eringen Micropolar fluid in a curvilinear coordinates system. The governing systems of non-linear partial differential equations consist of mass flux equation, linear momentum equations, angular momentum equation, and energy equation. The transformed ordinary differential equations for linear and angular momentum along with energy were solved numerically with the help of the Keller box method. Numerical and graphical results were obtained to analyze the flow characteristic. It is perceived that by keeping the dynamic viscosity temperature dependent, the velocity of the fluid away from the surface rose in magnitude with the values of the magnetic parameter, whil... [more]

Achieving emulsion stability in the petroleum industry is a major challenge due to several problems encountered in the oil refining process, such as corrosion in equipment, high-pressure drops in pipelines, and catalyst poisoning in upstream facilities. Thus, several methods are applied for emulsion treatment and chemical treatment using surface-active agents, a fundamental method in the petroleum industry. The present work investigated the performance of a non-ionic surfactant in separating water in a crude oil emulsion via the bottle test technique. Then, a Fractional Factorial Design (2K−1) was used to characterise the effect of significant variables. In particular, a Pareto chart was employed and factors such as demulsifier dosage, toluene concentration, pressure, sitting time, and temperature were investigated. Accordingly, the parameters applied were further analysed using a Central Composite Design (CCD) based on the Response Surface Method (RSM). The experimental results based... [more]

In this work, oxidizing roasting was combined with leaching to separate copper, lead, and zinc from a concentrate obtained by bulk flotation of a low-grade ore sourced from the Jiama mining area of Tibet. The flotation concentrate contained 7.79% Cu, 22.00% Pb, 4.81% Zn, 8.24% S, and 12.15% CaO; copper sulfide accounted for 76.97% of the copper, lead sulfide for 25.55% of the lead, and zinc sulfide for 67.66% of the zinc. After oxidizing roasting of the flotation concentrate, the S content in the roasting slag decreased to 0.22%, indicating that most sulfide in the concentrate was transformed to oxide, which was beneficial to leaching. The calcine was subjected to sulfuric acid leaching for separation of copper, lead, and zinc; i.e., copper and zinc were leached, and lead was retained in the residue. The optimum parameters of the leaching process were: a leaching temperature of 55 °C; sulfuric acid added at 828 kg/t calcine; a liquid:solid ratio of 3:1; and a leaching time of 1.5 h. Un... [more]

The current article discussed the heat transfer and thermal radioactive of the thin liquid flow of Sisko fluid on unsteady stretching sheet with constant magnetic field (MHD). Here the thin liquid fluid flow is assumed in two dimensions. The governing time-dependent equations of Sisko fluid are modeled and reduced to Ordinary differential equations (ODEs) by use of Similarity transformation with unsteadiness non-dimensionless parameter S t . To solve the model problem, we used analytical and numerical techniques. The convergence of the problem has been shown numerically and graphically using Homotopy Analysis Method (HAM). The obtained numerical result shows that the HAM estimates of the structures is closed with this result. The Comparison of these two methods (HAM and numerical) has been shown graphically and numerically. The impact of the thermal radiation R d and unsteadiness parameter S t over thin liquid flow is discovered analytically. Moreover, to know th... [more]

The current study introduces a new technique for the analysis of uncertain systems and uncertain processes in geothermics/earth sciences. The method is the second synthetic grey relational analysis (SSGRA) model, which incorporated the advantages of both Deng’s GRA model and the bidirectional absolute GRA model. The SSGRA model has been earlier successfully applied in project management and healthcare systems. The current study is a pioneer in demonstrating the feasibility of the SSGRA model in a geothermal environment. In the current study, the model was used to determine the associations between thermal conductivity and petrophysical parameters in an Algerian reservoir. The results revealed that thermal conductivity is most strongly associated with porosity followed by density and permeability. Their relationships are also discussed. The study concludes with valuable insights about the model and its application in engineering and natural sciences especially when the system contains u... [more]

Representative volume element (RVE) is an important parameter in numerical tests of mechanical properties of heterogeneous geomaterials. For this study, a digital image processing (DIP) technology was proposed for estimating the RVE of heterogeneous geomaterials. A color image of soil and rock mixture (SRM) with size of 400 × 400 mm2 taken from a large landslide was used to illustrate the determination procedure of the SRM. Six sample sizes ranging from 40 × 40 mm2 to 240 × 240 mm2 were investigated, and twelve random samples were taken from the binarized image for each sample size. A connected-component labeling algorithm was introduced to identify the microstructure. After establishing the numerical finite difference models of the samples, a set of numerical triaxial tests under different confining pressures were carried out. Results show that the size of SRM sample affects the estimation of the mechanical properties, including compressive strength, cohesion, and internal friction an... [more]

Conventional microwave heating has serious problems such as non-uniform heating and low efficiency. A novel magnetron microwave sweep frequency heating method is proposed to improve microwave heating uniformity. In this method, the frequency-sweeping signal is injected into the magnetron by the injection frequency-locking technique, and the microwave sweep frequency heating of the magnetron is realized. In this paper, a complicated injection frequency locking system is given and analyzed and a multiphysics calculation model based on the finite element method for electromagnetic waves and heat transfer is established. The calculation of microwave sweep frequency heating is realized by the combination of COMSOL and MATLAB. The results show that the sweep frequency heating has an obvious superiority. An experiment is carried out to verify the simulation results. The simulation results are in agreement with the experimental data. Moreover, the effect of sweep bandwidth and sweep interval o... [more]