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We have designed and fabricated four previously unexplored body-centered cubic (BCC) single phase VCrMo, VCrMoNb, VCrMoTa, and VCrMoNbTa refractory medium- to high-entropy alloys using a simple thermodynamic approach. The effectiveness of this approach was further theoretically and experimentally demonstrated by using calculation of phase diagrams (CALPHAD) simulations and arc-melting synthesis, respectively. The elemental segregation could be successfully predicted by the Scheil–Gulliver model. All the samples exhibited as-cast dendritic microstructures with high microhardness values. Finally, a general route is proposed to design equiatomic and non-equiatomic medium- to high-entropy alloys based on the rational selection of a binary system and by adding a premeditated amount of principal elements using a simple thermodynamic parameter.

Plate heat exchangers (PHE) are of primary importance for many technical applications. To use PHE effectively it is necessary to calculate the pressure drop correctly. Unfortunately, in open literature a large difference between the different authors occurs. As shown in an earlier work (Gusew and Stuke in Int J Chem Eng vol. 2019, 6) an essential portion of this difference lies in the pressure drop of the distribution zone. In this work new geometrical parameters are introduced to calculate the pressure drop of the distribution zone. The resulting correlations with new parameters include the pressure drop of both corrugated field and distribution zones. This new three-component model for hydraulic resistance show good agreement with experimental data for PHEs in turbulent flow regime. Furthermore, observed differences in data of other authors can be explained by the influence of the new introduced geometrical parameters of the distribution zone.

The composition is a significant issue for corrosion resistance of metallic materials. To reveal the correlation of corrosion behavior between multiprinciple alloys and their constituents, a series of single-phase equiatomic alloys of CoCrNi, CoCrNiFe and CoCrNiFeMn was fabricated. The electrochemical and scanning electron microscope results demonstrated that corrosion resistance of the equiatomic alloys in 0.1 M NaCl solution is located in the range but not the average value of their constituents. X-ray photoelectron spectroscopy analysis indicated that the protective performance of passive film is mainly determined by the constituent with the highest corrosion resistance and the breakdown of passive film is mainly dominated by the elements with the highest corrosion rate. Our findings can guide the materials design of multiprinciple alloys with expected corrosion performance.

Anti-islanding protection plays a major role in grid-connected inverters which are based either on solar PV or other renewable energy resources when they are connected to the utility. In this study, six grid-connected string inverters were characterized based on the Indian standard IS 16169:2019. This paper presents the real-time simulation results of grid loss protection in both single- and three-phase solar grid-connected inverters when connected to the utility. The study shows that the three-phase string inverters have lesser disconnection times in comparison with the single phase. With the increase in power capacity of string inverters, it is observed that irrespective of single or three phases, the disconnection time decreases.

Recrystallization has been a major method to induce heterogeneous grain structure for improving the strength–ductility combination of single-phase high-entropy alloys (HEAs). However, the recrystallization kinetics, which are the guideline for controlling the recrystallization behavior, of single-phase HEAs are relatively less explored. Here, we uncover the recrystallization behaviors of typical single-phase NiCoCrFe and Ni2CoCrFe HEAs. Our results showed that the two investigated HEAs exhibit almost similar recrystallization activation energy around 230 kJ·mol−1, but distinctively different recrystallization kinetics. This abnormal difference is attributed to the deformation twins of NiCoCrFe. These findings indicate that, except for textbook factors, deformation twinning significantly enhances the recrystallization behavior of HEAs.

The goal of this study was to determine whether the benefits of multiphase CTA (mCTA) over single-phase CTA (sCTA) for the detection of proximal cerebrovascular occlusions similarly extend to the distal cerebral vasculature. Four attending radiologists, two neuroradiologists and two emergency radiologists, contributed as readers to this retrospective study. For each reader, two sessions were conducted, one using sCTA and one using mCTA. During each session, the reader interpreted the studies of 104 patients who underwent imaging for suspicion of acute ischemic stroke, resulting in a total of 832 interpretations. Changes in diagnostic accuracy, time to render final decision, and reported levels of reader confidence were quantitatively assessed. Further analysis comparing the effects for neuroradiologists versus emergency radiologists was additionally conducted. Using mCTA resulted in a significant 5.0% absolute increase in sensitivity (91.6% vs. 96.6%, p = .004) and an insignificant increase in specificity (99.5% vs. 99.7%, p = .39). A significant reduction in reading time (66.7 s vs. 59.6 s, p = .001) and an increase in diagnostic confidence (2.26 vs. 2.58, p

Abstract Refractory ‘stuffed’ pyrochlores such as Gd2TiO5 are of interest for nuclear applications, including as matrices for actinide disposition and as neutron absorbers in control rods. Here, we report the results of a preliminary comparative investigation of the synthesis of Gd2TiO5 by molten salt and conventional solid-state synthesis. We show that synthesis of Gd2TiO5 proceeds from the pyrochlore phase Gd2Ti2O7 which is first formed as a kinetic product. Molten salt synthesis afforded single phase Gd2TiO5 at 1300 °C in 2 h, via a template growth mechanism, and is effective for the synthesis of these refractory materials. This work demonstrates molten salt mediated synthesis of ‘stuffed’ pyrochlore for the first time. Graphic abstract

Silicon sulfide (SiS2) was synthesized from Si, SiC, Si3N4, and a eutectic Al-Si liquid. An Ar-CS2 gas mixture, after bubbling through liquid CS2, was passed over pulverized Si, SiC, Si3N4, or a eutectic Al-Si alloy liquid. White, needle-shaped SiS2 was precipitated as a single phase on the colder downstream surface when Si powder in a SiO2 liner was heated over 1273 K. This deposition mechanism involves a reaction between Si and CS2 to form SiS2, with the vaporization of SiS(g) and deposition as SiS2(s) from SiS(g) and S2(g). Quartz was unaffected by the reaction gases. Notably, Si, SiC, Si3N4, and the eutectic Al-Si liquid were found to be suitable sources for SiS2 synthesis, although this was suppressed owing to Al2S3 formation on the latter.

A simulation model of a linear high-frequency path of an overhead power line (OPL) implemented in the PSCAD software environment is considered. The model allows studying the transmission of location signals in the OPLs of 6 – 35 kV distribution networks in the presence of single-phase-to-earth faults (SPEF). Simulated and experimental TDR traces for various SPEFs are compared. Methods of location-based determination of the SPEF distance and location are described.

To optimize the comprehensive electrical performances of lead-free piezoelectric ceramics, (1-x)(Ba0.85Ca0.15)(Ti0.9Zr0.1)O3-xLiTaO3-0.3 mol% GeO2 (abbreviated as (1-x)BCZT-xLT-0.3 mol%G, 0 ≤ x ≤ 0.5) ceramics were prepared by conventional solid-state sintering method. The structures and electric properties of ceramics were systemically studied through XRD, Raman spectra, er-T, SEM, and P–E, respectively. The results show that the piezoelectric properties can be affected by phase coexistences for different doping contents. Thereinto, the phase coexistences change from R-O at x = 0 to R-O/O-T at 0.1 ≤ x ≤ 0.2 and O-T at x = 0.3, respectively, while the R single phase is detected with x further increasing to 0.5. Correspondingly, the ceramics with multiphase coexistences at 0 ≤ x ≤ 0.3 obtain more excellent electrical properties than the ones with single phase at x = 0.5. In addition, the outstanding electric properties especially including the piezoelectric response are achieved at x = 0.2 mol% (e.g., d33 = 570 pC/N, kp = 0.61, er = 14,887, tanδ = 0.007, Pr = 8.51 µC/cm2, Ec = 0.18 kV/cm, respectively).

The paper presents a new generalized topology-based single-phase cascaded multilevel inverter with reduced power electronic switches, thereby reducing the driver circuits. A new basic unit is proposed in this paper. In order to generate required voltages at the output, an H-bridge is added in conjunction with the basic unit as the unit provides only positive voltage levels. Owing to the merits possessed by cascaded multilevel inverter such as reduction in switch count, driver circuits, low stresses in voltage and their power quality being high, a basic unit is developed. A comparison between the existing topologies and the proposed topology is presented. The developed cascaded 9-level multilevel inverter topology is validated with both simulations and experimentation.

β-Texture evolution during cooling after forging in the β single-phase region and (α + β) dual-phase region was investigated in Ti-6Al-2Sn-4Zr-6Mo alloy. Typical {001} and {111} β fiber textures of the β phase developed during forging. Dynamic-recrystallized β grains formed and inherited the orientation of their parent grains during forging in the β single-phase region. The {001} texture was enhanced with decreasing cooling rate after forging in the β region, that is, as cooling time in the β region increased. The results of the post-forging holding in the β region demonstrated that the recrystallized grains that grew in the β region consumed the adjacent {111}-oriented parent grains and initially enhanced the {001} texture. However, the enhancement of the {001} texture was moderated with increasing holding time because of the increased orientation deviation between the recrystallized grains and the parent grains. In addition, the {001} β texture was weakened by the growth of static-recrystallized grains after its incubation period during the holding time. These results indicate that growth of dynamic-recrystallized and static-recrystallized grains moderated the increase of the {001} texture intensity at low cooling rates of specimens forged in the β region. In specimens forged near the β-transus temperature and in the (α + β) dual-phase region, the {001} texture intensity was only slightly affected by the cooling rate. Recrystallization of the β phase was suppressed by the precipitation of the α phase during forging and cooling at low temperatures. A slow cooling rate of − 2 °C/s was determined by measuring the temperature change of a large specimen similar in size to those used in real-world applications.

The development of electronic technology is flexibly related to the progresses made in material science. Functional materials out of the broad class of materials available today offer unique chance for developing novel components and devices. In this framework, provides a new class of functional materials, the multiferroics (MFs), combine two or more different ferroic orders (viz. ferroelectric, ferromagnetic and ferroelastic) in a single phase and are utilized in a broad range of systems. In connection with multiferroism, a broad category of materials namely magnetoelectrics allow the electric control on magnetization or vice-versa are explored extensively. Even though, the research in the field of MFs and magnetoelectric (ME) materials can be traced back to revolutionary research in the early 1950s. There has been a contemporary resurgence of concern motivation by long-term technological aspirations. The center of attention of this review is on elementary understanding of the MFs and ME materials using a multidisciplinary approach to address the underlying mechanism responsible for the coupling, their applications in some novel devices, new opportunities and future challenges.

This paper reports a way to obtain BaPbO3-x and BaPb1/3Bi2/3O3-x perovskite-type compounds. The method is based on the initial preparation of Ba(COO)2·0.5H2O and Pb(COO)2·oxalates, and the subsequent calcination of the equimolar physical mixture of these oxalates until the desired compounds BaPbO3-x and BaPb1/3Bi2/3O3-x are formed. To obtain BaPb1/3Bi2/3O3-x, the oxide Bi2O3 is added to the mixture of oxalates and calcined together with them. The temperature for the formation of BaPbO3-x and BaPb1/3Bi2/3O3-x was estimated to be 850°C. These final compounds prepared by calcination were composed of a single phase and exhibited monoclinic crystal structure. The thermal decomposition of the Pb(COO)2 oxalate and the formation of BaPbO3-x and BaPb1/3Bi2/3O3-x were investigated by X-ray powder diffraction (XRPD) and differential thermal analysis (DTA).

The transient processes in a 20 kV network due to single-phase short circuit fault in the 220 kV lines of a 220/20 kV supply substation are considered. Combinations of parameters at which overvoltages are the highest are determined. The overvoltages limited by surge arresters installed on 20 kV busbars are estimated.

High entropy and sluggish diffusion “core” effects were investigated in an FCC Al-Co-Cr-Fe-Ni alloy by examining the nonequiatomic compositions generated by the concentration profiles within the solid-to-solid diffusion couple, Al48Ni52vs Co25Cr25Fe25Ni25, annealed at 900 °C, 1000 °C, 1100 °C, and 1200 °C. The average effective interdiffusion coefficients of individual components and the maximum solubility limit of Al in nonequiatomic Al-Co-Cr-Fe-Ni alloys were determined as a function of temperature. The magnitudes of the average effective interdiffusion coefficients in Al-Co-Cr-Fe-Ni alloys were compared to the interdiffusion coefficients in relevant ternary and quaternary alloys. The solubility limit of Al in nonequiatomic AlpCoqCrrFesNit alloys was compared to that of Al in equiatomic AlxCoCrFeNi determined from the equilibrium pseudo-binary phase diagram. A reduction in the magnitude of interdiffusion coefficients was not observed for individual components in Al-Co-Cr-Fe-Ni alloys. The maximum solubility of Al in nonequiatomic AlpCoqCrrFesNit alloys was observed to be higher than that in equiatomic AlxCoCrFeNi alloys at a temperature of 1100 °C or above. Correspondingly, the free energy of mixing for nonequiatomic AlpCoqCrrFesNit alloys was determined to be lower than that of equiatomic AlxCoCrFeNi alloys at a temperature of 1100 °C or above. At a temperature of 1100 °C or above, the role of enthalpy of mixing was estimated to be significant in achieving higher thermodynamic stability of the nonequiatomic AlpCoqCrrFesNit alloy than in the equiatomic AlxCoCrFeNi alloy for the compositions corresponding to the highest solubility limit for Al. The compositions of nonequiatomic AlpCoqCrrFesNit alloys were observed to follow the existing empirical rules for the formation of single phase in high entropy alloys (HEAs).

Wear behavior of a single-phase laser-clad Cu-9Ni-6Sn coating was investigated against high-carbon steel ball in a ball-on-disc linear wear tester in air and in a 3.5 wt.% NaCl solution, compared with the commercial wear-resistant Cu-10Ni alloy. The wear resistance of a single-phase laser-clad Cu-9Ni-6Sn coating was higher than that of Cu-10Ni alloy in both air and NaCl solution. For the sliding process in air, a continuous, compacted and adherent oxide layer was formed on the sliding surface of Cu-9Ni-6Sn coating due to the combined effects of spinodal decomposition, Sn-rich precipitates and grain refinement. In contrast, such a layer was not seen on the sliding surface of Cu-10Ni alloy. For the sliding process in NaCl solution, Cu-9Ni-6Sn coating exhibited the high hardness and excellent corrosion resistance compared to Cu-10Ni alloy, which was responsible for the better wear resistance of Cu-9Ni-6Sn coating. Clearly, a single-phase laser-clad Cu-9Ni-6Sn coating exhibited the high wear resistance in both air and NaCl solution, resulting in the excellent application prospect in many industries.

The particulars of the adaptation of the CONV-3D module for modeling turbulent flows in reactors in the LES approximation are presented. The results of modeling coolant flow in a round tube with Reynolds number 4·103–5·105 in comparison with the Blasius formula are presented. It is shown that the adapted module gives numerical results that coincide with the analytical estimates and DNS calculations but on much coarser grids, so that the calculations can be speeded up several-fold.

The effect of Ni content on microstructure and mechanical properties of the CrMnFeCoNi high entropy alloy (HEA) has been studied. The Ni content varied from 0 to 20 at% in the composition (CrMnFeMn)100−xNix, where x = 0, 2.5, 5, 10, 15, and 20 at%. The alloys were synthesized by vacuum arc melting and the microstructure as well as hardness of the as-cast alloys were studied. Alloys with low Ni content (x ≤ 2.5%) consists of a two-phase microstructure of dendritic and inter-dendritic regions with fcc (matrix) and tetragonal (sigma) crystal structure, respectively. When the Ni content is 5 at%, two-phase structure with fcc (matrix) and bcc (secondary phase) is observed, with the addition of Mn-rich inclusions that are present in the entire matrix. Alloys with higher Ni content (x ≥ 10, at%) exhibit a single phase of fcc structure. Hardness of the HEAs decreases from 320 to 120 Hv with increase in Ni content, and the high hardness of these alloys with low Ni content is due to the mixture of both fcc and hard tetragonal (sigma) phases.

The paper deals with a simulation study of influence of conductive material of the rotor squirrel cage on output characteristics of single-phase self-excited induction generators. For calculation of performance characteristics, two-dimensional field-circuit model of the single-phase induction generator was applied. A comparison of self-excitation waveforms of terminal voltage and load characteristics of the generators for rotor bars of the same shape, made of aluminium and copper, was presented. The obtained simulation results by the field-circuit model and analysis may be utilized for designing new constructions of single-phase self-excited induction generators as well for modifying construction of the generators designing on the base of general-purpose single-phase induction motors.

A series of titanium-vanadium-tantalum (Ti-V-Ta) medium entropy alloys have been fabricated with all of them exhibiting a single-phase body-centered cubic structure in the homogenized states, and their thermal stability as well as their mechanical properties have been investigated. Among the four studied alloys, Ti27V33Ta40, Ti33V33Ta34, Ti40V33Ta27, and Ti45V20Ta35, the equi-atomic Ti33V33Ta34 has shown the highest thermal stability, without secondary phases formed after annealed at 400–700°C for 48 h, while decompositions have been observed in the other three alloys. All the four alloys have exhibited a good compression strength of 394–527 MPa at 800°C, while, except Ti27V33Ta40, maintaining an acceptable tensile ductility with fracture strains of 7.6–13% at room temperature. Furthermore, the low neutron activity of the Ti-V-Ta alloys grant them application potentials in nuclear engineering.

Effects of microstructure constituents of α2-Ti3Al/γ-TiAl lamellae, β-Ti grains and γ grains, with various volume fractions on room-temperature ductility of γ-TiAl based alloys have been studied. The ductility of the alloys containing β phase of about 20% in volume increases to more than 1% as the volume fraction of γ phase increases to 80%. However, γ single phase alloys show very limited ductility of less than 0.2%. The present results, thus, confirmed the significant contribution of β phase to enhancement of the room-temperature ductility in multi-component TiAl alloys.

This paper investigates different current reference generation schemes for the control of single-phase inverter-based distributed generator with model predictive control-based space vector modulation and asynchronous sigma–delta modulation schemes. The current references for the developed controller have been deduced from three different schemes, known as scalar, modified scalar and simplified active and reactive power control. The performance of the developed controllers with considered current reference generation schemes is examined for different real and reactive power feedings from the single-phase generator to the grid.

Ba0.5Sr0.5Co1−xFexO3−δ (BSCF) is a well-recognized cathode material for IT-SOFC. In this work, Ba0.5Sr0.5Co1−xFexO3−δ (BSCF) where x = 0.2, 0.4, 0.6, 0.8 compositions were synthesized by gel-combustion method using glycine as a fuel. Powder X-ray diffraction confirms the formation of single phase for all the compositions. As we are looking for the application of BSCF cathode for proton-conducting SOFCs, compatibility studies were made with BaCe0.8Y0.2O3−δ (BCY), BaCe0.4Zr0.4Y0.2O3−δ (BCZY) and BaZr0.8Y0.2O3−δ (BZY) electrolytes which are known to have good proton-conducting properties at elevated temperatures. Ba0.5Sr0.5Co0.4Fe0.6O3−δ (BSC4F6) and Ba0.5Sr0.5Co0.2Fe0.8O3−δ (BSC2F8) compositions showed good chemical compatibility with selected electrolyte materials at cell fabrication as well as cell operating temperature making them an appropriate cathode material. Electrical property of all the BSCF compositions was measured in air up to 1073 K by four-probe dc technique. The results showed very little effect of Fe substitution on electrical properties.

Ca-Mg-Si films were firstly prepared on (001)Al2O3 substrates by RF-magnetron sputtering method from Mg disc target together with Ca and Si chips. The composition of the deposited films was controlled by adjusting deposition temperature and Ca/Si area ratio of Ca and Si chips on Mg disk target. Ca0.32Mg0.33Si0.35 film deposited at 610 K consisted of a single phase of CaMgSi and this CaMgSi phase was stable after heat treated at 770 K under an atmospheric Ar with 5% -H2. As-deposited film shows the semiconductor behavior and have a power factor of 50 µW/(mK2) at 670 K, while annealed one showed the metallic behavior and its power factor down below 10 µW/(mK2) at 320-770 K. On the other hand, Ca0.27Mg0. 51Si0.2 film deposited at 590 K showed no obvious crystalline phase but became single phase of Ca7Mg7.25Si14 after heat treatment at 770 K under an atmospheric Ar with 5% -H2. As deposited film had a large power factor of 100 µW/(mK2) at 670 K. However, power factor decreased below 1 µW/(mK2) at 320-770K after the heat treatment at 770 K under an atmospheric Ar with 5% -H2.

In this paper functional relationships between bayonet-tube heat exchanger effectiveness (P), heat capacity ratio (R) and number of transfer units (NTU) for all possible flow arrangements are derived. Temperature profiles of hot and cold fluid are also given. Analysis showed that regarding heat exchanger surface eight possible flow arrangements can be reduced to four. Furthermore it has been shown which flow arrangements have superior thermal performances. Developed methodology was illustrated through the numerical example.

Single-phase multiferroic materials are usually considered useless because of the weak magnetoelectric effects, low operating temperature, and small electric polarization induced by magnetic orders. As a result, current studies on applications of the magnetoelectric effects are mainly focusing on multiferroic heterostructures and composites. Here we report a room-temperature giant effect in response to external magnetic fields in single-phase multiferroics. A low magnetic field of 1000 Oe applied on the spin-driven multiferroic hexaferrites BaSrCo2Fe11AlO22 and Ba0.9Sr1.1Co2Fe11AlO22 is able to cause a huge change in the linear magnetoelectric coefficient (αE = dE/dH) by several orders, leading to a giant magnetotranstance (GMT) effect at room temperature. The GMT effect is comparable to the well-known giant magnetoresistance (GMR) effect in magnetic multilayers, and thus opens up a door toward practical applications for single-phase multiferroics.

Investigations on Ti, Pr, and Dy substitution and Ti co-substitution with La, Ce, Pr, Nd, and Dy in Y site were carried out. The XRD patterns indicate that the solubility limit for Ti is 5%. The solubility limit for Dy is 100%. Impurities will form if the substituting proportion surpasses the solubility limit for the substituting ion. For the phase composition of all co-substitution samples, only Ti and Dy substituted one is essentially single phase. The largest oxygen content δ reached 1.054, 1.188 and 1.070 for Y0.95Ti0.05BaCo4O7+δ, DyBaCo4O7+δ, Y0.2Ti0.05Dy0.75BaCo4O7+δ, respectively. The largest oxygen content δ reached was 0.900 for Y0.25Pr0.75BaCo2O5+δ.

The Li2(Mg0.9A0.1)4TiO7 (A = Co2+, Ni2+, Mg2+, Zn2+, Ca2+) ceramics were prepared by the conventional solid-state reaction method. A series of Li2(Mg0.9A0.1)4TiO7 ceramics were investigated in regard to the sintering temperatures, crystal structures and dielectric properties. The Li2(Mg0.9A0.1)4TiO7 ceramic exhibited a single phase of Li2Mg4TiO7, and the Rietveld refinement was used to analyze the crystal structure. The Li2(Mg0.9Ca0.1)4TiO7 ceramics could be sintered below 1350 °C with high densities, high dielectric constants and near zero τf values. The maximum Q·f value of Li2(Mg0.9Zn0.1)4TiO7 was higher than that of Li2(Mg0.9A0.1)4TiO7 (A = Co2+, Ni2+, Mg2+, Ca2+). The optimum microwave dielectric properties of er = 14.77, a high Q·f value of 162,200 GHz and τf = − 4.30 ppm/°C were achieved in Li2(Mg0.9Zn0.1)4TiO7 ceramic sintered at 1500 °C. In addition, Li2(Mg0.9Ca0.1)4TiO7 ceramic sintered at 1300 °C exhibited the suitable dielectric properties with a high er value of 15.79, Q·f = 100,300 GHz and a near zero τf value of − 1.43 ppm/°C.

A series of green-to-red color-tunable K3Tb1−xEuxB6O12 phosphors were synthesized via the high temperature solid-state reaction method. The crystal structure, morphology, luminescent properties and energy transfer of K3Tb1−xEux B6O12 were systematically investigated in detail. The obtained phosphors display both a green emission of Tb3+ and a red emission of Eu3+ with considerable intensity under ultraviolet excitation (377 nm). The emission colors of the phosphors can be tuned from green (0.291, 0.598) through yellow (0.528, 0.428), orange (0.573, 0.387) and eventually to red (0.629, 0.357) by adjusting the x values. These results show that the K3Tb1−xEuxB6O12 phosphors may find potential applications in the field of displays and lighting.

This paper serves as a brief introduction to the longer introduction provided by the book by Nield and Bejan (NB). Attention is focussed on the modelling of the interaction of the heat transfer and the presence of a porous medium. Except for a brief mention, convection in unsaturated media is beyond the scope of this book and hence this review. Our coverage is mainly confined to single phase flow. The effects of radiation considered are confined to a contribution to volumetric heating produced by the absorption of radiation. Topics covered relate to both pore scale (microscale) and macroscale modelling and processes. Both theoretical and experiment studies are considered. Whilst NB contains a section on deformable media, the book is largely constrained to rigid porous media. This review is confined to matters concerning rigid porous media.

Cr2N is commonly found as a minority phase or inclusion in stainless steel, CrN-based hard coatings, etc. However, studies on phase-pure material for characterization of fundamental properties are limited. Here, Cr2N thin films were deposited by reactive magnetron sputtering onto (0001) sapphire substrates. X-ray diffraction and pole figure texture analysis show Cr2N (0001) epitaxial growth. Scanning electron microscopy imaging shows a smooth surface, while transmission electron microscopy and X-ray reflectivity show a uniform and dense film with a density of 6.6gcm(-3), which is comparable to theoretical bulk values. Annealing the films in air at 400 degrees C for 96h shows little signs of oxidation. Nano-indentation shows an elastic-plastic behavior with H=18.9GPa and E-r=265GPa. The moderate thermal conductivity is 12Wm(-1)K(-1), and the electrical resistivity is 70cm. This combination of properties means that Cr2N may be of interest in applications such as protective coatings, diffusion barriers, capping layers and contact materials. Funding Agencies|European Research Council under the European Communitys Seventh Framework Programme (FP/2007-2013)/ERC Grant [335383]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [200900971]; Swedish Foundation for Strategic Research (SSF) through the Future Research Leaders 5 program; Knut and Alice Wallenberg foundation through the Wallenberg Academy Fellows program; Swedish Research Council (VR) [2016-03365]; Aforsk Foundation [16-359]; Carl Tryggers Foundation [CTS 17:166]

Phosphate compound with mixed cations, NaBaPO4 can be a new candidate of microwave dielectric ceramics with the basis of the systematically investigations of the ternary compound series of AMPO4 (A = Li, Na, K; M = Ca, Sr, Ba). Ceramics with single phase of NaBaPO4 can be obtained under our optimized experimental sintering conditions for this compounds above, whereas its microstructures and microwave dielectric properties are strongly influenced by the sintering temperatures and holding times. Relatively dense microstructures can be obtained under the sintering conditions of 910 °C/0.5 h, with unique combination of microwave dielectric properties as e = 8.279, Q × f = 10237 GHz (11.4 GHz) and τf = + 19.07 ppm/°C, and fast sintering characteristics (0.25 – 0.5 h) are the inherent properties of such phosphate compound.

For single-phase earth faults (SEF) in a generator network, the higher harmonic components are a good information base for relay protection of the generator against single-phase earth faults. Because of the low signal-to-noise ratio, they are not available for direct measurement. Anew method of active-adaptive recognition of similar signals is proposed. The results of testing a prototype of the generator protection device with an active-adaptive analog-to-digital converter (ADC) path confirm the high effectiveness of the proposed method.

The 0.2Li2ZrO3–0.8MgO (Li2Mg4ZrO7) ceramics were prepared by conventional solid-state reaction method. The effects of lithium fluoride (LiF) addition on the microstructure, sintering temperature and microwave dielectric properties of Li2Mg4ZrO7 ceramics were investigated. The experimental results demonstrated a typical single phase existed in Li2Mg4ZrO7–LiF ceramics, in which LiF was proved to be an effective sintering aid for the Li2Mg4ZrO7 ceramic. LiF obviously lowed the optimum sintering temperature of Li2Mg4ZrO7 ceramic from 1500 to 1050 °C and improved the sintering ability of the matrix. In this paper, the microwave dielectric properties were strongly dependent on the amount of LiF additions and the sintering temperature. Optimum microwave dielectric properties (er = 12.95, Q·f = 180,011 GHz and τf =− 23.51 ppm/°C) were obtained in Li2Mg4ZrO7-4 wt% LiF ceramics sintered at 1050 °C.

A depth-averaged quasi single-phase mixture model is proposed for debris flows over inclined bed slopes based on the shallow water hydrosediment-morphodynamic theory with multi grain sizes. The stresses due to fluctuations are incorporated based on analogy to turbulent flows, as estimated using the depth-averaged k − e turbulence model and a modification component. A fully conservative numerical algorithm, using wellbalanced slope limited centred scheme, is deployed to solve the governing equations. The present quasi single-phase model using four closure relationships for the bed shear stresses is evaluated against USGS experimental debris flow and compared with traditional quasi single-phase models and a recent physically enhanced two-phase model. It is found that the present quasi single-phase model performs much better than the traditional models, and is attractive in terms of computational cost while the two-phase model performs even better appreciably.

Stochastically occurring voltage sags as they may occur with low quality of the power supply may significantly affect the operational behavior of single-phase starting and running capacitor assisted induction machines. In contrast to three-phase machines which are still subjected to a rotating field, even during voltage sags, the single-phase machines are subjected to an alternating field that can be decomposed into two rotating fields, a positive and a negative sequence one. Thus, the behavior of these machines when submitted to voltage sags cannot be directly derived from the established understanding of the low voltage ride through capability of three-phase machines. The effects of such voltage sags on a single-phase machine’s transient behavior not only depend on the electric capacitive circuit and the machine’s electromagnetic design, but strongly on the moment the short circuit occurs, its duration, and the load of the machine. In this work, we analyze the robustness of such a system towards an extremely voltage sag, in particular a terminal short circuit. To this aim, experimentally validated transient FE computations are used.

In this paper, the performance of distance relay during single-phase reclosing (SPAR) period is considered. Available distance relaying schemes are affected during SPAR period as the pre-fault signals include both negative- and zero-sequence components. Fault resistance, voltage ratio, load angle, shunt capacitive effect, and other system conditions along with SPAR further make distance estimation erroneous. The proposed adaptive scheme is based on the derivation of the impedance at the relay location using symmetrical component theory. The proposed scheme has been employed to measure the correct value of the fault impedance during SPAR period with variation in different system conditions. This approach also works for without SPAR condition. The performance of the proposed technique is tested using the transient data obtained from the single-circuit line simulated using PSCAD/EMTDC software. Performance of the proposed algorithm is verified using a hardware-in-loop test bed having real-time digital simulator and dSPACE.

High efficiency and fast dynamic response are two main control objectives for dual active bridge (DAB) DC-DC converters. Traditional extended phase shift (EPS) control can significantly enhance the conversion efficiency of DAB DC-DC converters by reducing current stress; however, it cannot fulfill fast dynamic response requirements. In this paper, a novel hybrid control scheme consisting of EPS control and direct power control (DPC), named as EPS-DPC, is proposed. EPS-DPC control has salient features in both efficiency and dynamic performance. In order to verify the outstanding performance of the proposed EPS-DPC scheme, an experimental comparison was carried out on a scale-down DAB DC-DC converter among several control strategies, including single phase shift control with traditional voltage-loop (SPS-TVL), EPS control with traditional voltage-loop (EPS-VTL), and EPS-DPC. Experimental results have been high consistent with theoretical analysis, and verified these advantages of the proposed EPS-DPC scheme.

Fine particles within porous media may migrate with the flowing fluid and cause bridging or clogging in the pore space. Bridging and clogging reduce the flow permeability of porous media, which has a significant influence on petroleum engineering applications such as water and oil extraction, sand production, and gas production from hydrate-bearing sediments. Although the migration of fine particles and its impact on bridging and clogging have been investigated for a single-phase flow, it has not been understood clearly for a multi-phase flow. This work reports an approach using microfluidic pore models to study the migration of fine particles and the bridging/clogging behavior in a structure mimicking porous media. Results from the microfluidic model show that: (1) fine particles accumulated along the water and gas (CO2) interface; (2) fine particle concentrations in pores locally increased due to the accumulated particles at the interface, and (3) consequently bridging and clogging occurred in the pore throat. Findings from this work provide a starting point in understanding complex phenomena including a reduced flow permeability of porous media on a fluid containing fine particles for a variety of petroleum engineering applications. 2017, Springer-Verlag GmbH Germany. Acknowledgement This research was made possible by NPRP Grant # NPRP8-594-2-244 from Qatar National Research Fund (a member of Qatar Foundation). The findings achieved herein are solely the responsibility of the authors. Scopus

Novel single-phase full-color-emitting Ba9Lu2Si6O24:Ce3+/Mn2+/Tb3+ phosphors were successfully synthesized by a high-temperature solid-state reaction method. Analysis of the X-ray diffractograms of the produced phosphors suggests that all the luminescence doping cations preferably occupy the Ba2+ sites in the host lattice. Li+ were used according to Ce3+ and Tb3+ concentration as a charge compensation regent. Under UV excitation, the single Ce3+-doped phosphor exhibits an intense blue emission band that peaks at 424 nm. In the co-doped phosphors, the experimental results suggest that an efficient energy transfer mechanism from Ce3+ to Tb3+ and Mn2+ results in the generation of a green emission in the Tb3+-doped phosphors and a red emission in the Mn2+-doped ones. The triple-doped phosphors, which contained specific concentrations of Ce3+, Mn2+, and Tb3+ ions, generated a tunable (in a wide range) white light which had good color rendering index values. Thermal behavior of the present phosphors was investigated which shows better characteristics. This result qualifies the produced powders as potential single-phase trichromatic white light-emitting phosphors.

The Magnetoelectric (ME) effect has been observed in single phase hexaferrite bulk and thin films of SrCo2Ti2Fe8O19. In this paper we demonstrate that the ME linear coupling depends strongly on the Co ion concentration relative to the Ti ion concentration exhibiting extremum points at a concentration consistent with above formula. The Alternating Target Laser Ablation Deposition technique was utilized to deposit ME hexaferrite films for the first time. This allows for the deposition of transition metal ions at specific sites in the basic unit cell of the hexaferrite.

Manganese–zinc (MnZn) ferrite nanoparticles were synthesized via a hydrothermal method, and their structural and magnetic properties were studied. It was found that a low Fe content and the hydrothermal temperature play crucial roles in the synthesis of single phase MnZn ferrites. The hydrothermal temperature also affects the topography and the magnetic properties markedly. The best soft magnetic properties of M s = 45.5 emu/g and H c = 0.68 kA/m were obtained for the specimen with a Fe deficiency of 7% in the starting materials and hydrothermally synthesized at 180 °C.

A description is provided of the operating mode of a line equipped with a thyristor-controlled shunt reactor (TCSR) with split valve-side windings, in a single-phase ARC (SPAR) cycle after arc quenching. It is shown that a TCSR is sufficiently fast to prevent the development of resonant overvoltages in the open-phase operating mode of a power transmission line (PTL).

The Ba2P2O7:Tb3+, R (R = Eu2+, Ce3+) phosphors were synthesized by use of a co-precipitation method. Crystal phase, excitation and emission spectra of sample phosphors are analyzed by means of XRD and FL, respectively. The emission spectra of Ba2P2O7:Ce3+, Tb3+ phosphors exhibit four linear peaks attributed to the 5D4 → 7FJ (J = 6–3) transition of Tb3+ while four broad emission bands are observed in the emission spectra of Ba2P2O7:Eu2+, Tb3+ phosphors. The effects of Eu2+ concentration on the luminescent properties of Ba2P2O7:Tb3+, R (R = Eu2+, Ce3+) are studied. Ce3+ affects the luminescent properties of Ba2P2O7:Ce3+, Tb3+ phosphors just as the sensitizer. However, Eu2+ is considered both as the sensitizer and the activator in Ba2P2O7:Eu2+, Tb3+ phosphors. The chromaticity coordinates of Eu2+ and Tb3+ co-doped phosphors gather around the white light field with the CCT approximate to 5000 K, indicating that the luminescent property of Ba2P2O7:Eu2+, Tb3+ phosphors may approach to a desired level needed for white LED application.

In order to enhance the stability of single-phase microgrid, virtual synchronous generator (VSG) control method is investigated in this paper. Its electromagnetic model and electromechanical model are established to illustrate the performance of VSG. Considering the 2nd fluctuation of fundamental-frequency in the output power, an instantaneous power calculation strategy is proposed based on the intrinsic frequency of single-phase VSG. Besides, a virtual power calculation method is presented to achieve islanded/grid-connected seamless transition. Stability analysis and comparison simulation results demonstrate the correctness of the presented power calculation method. At last, the effectiveness of the proposed approach is verified by comparison experiments of islanded/grid-connected operations in a 500 VA single-phase inverter.

Ca substituted Sr5Ta4TiO17 ceramics were fabricated via solid state mixed oxide route. For all the investigated compositions, single phase was obtained. All the investigated ceramics crystallized into an orthorhombic crystal structure with space group Pnnm. Sr5Ta4TiO17 exhibited lower τf (~180 ppm/°C) and higher Q u f o (~8500 GHz) than its Nb analog compound (Sr5Nb4TiO17). The Ca substitution for Sr tuned the τf of Sr5Ta4TiO17 ceramics through zero and enhanced the Q u f o value at the cost of a decrease in er value. A good combination of microwave dielectric properties i.e. er ~49, Q u f o ~13560 GHz and τf ~−9 ppm/°C was achieved for SrCa4Ta4TiO17 ceramics sintered at 1575 °C for 4 h respectively.