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A dual-band frequency selective surface (FSS) employing Ti3C2Tx deposited on a polyethylene terephthalate (PET) layer is proposed for Wi-Fi applications. The structure can afford dual-frequency pas...

Impingement cooling is conducive to enhancing the cooling performance of turbine blade trailing edge channel, and slot ejection can be adopted for additional cooling. This paper explores the influe...

Rare-earth zirconate ceramics are conventionally sintered at high temperatures for long durations to achieve a full density. Herein, we synthesized and densified five lanthanide-group rare-earth zirconates (Ln2Zr2O7, Ln = La, Nd, Sm, Eu, Gd) containing different numbers of Ln cations in a high-throughput mode using a novel ultrafast high-temperature sintering technique within a cycle of 5 min, and investigated the effects of components on the structure and properties of the resultant ceramics. Under the high-throughput mode, the same sintering conditions make the analysis and comparison of the results more reasonable. The average grain size decreased while hardness and Young’s modulus increased with an increase in the number of the Ln components in the zirconate ceramics. The mechanisms were ascribed to the sluggish diffusion and lattice distortion effect caused by the increase in entropy.

Two new Zn(II)/Co(II) coordination polymers, [Zn1.5(pmda)(OH)(bipy)]2n·2nH2O (1) and [Co(pmda)(bib)]n (2) (H2pmda = 4,4′-[1,2-phenylenebis(methyleneoxy)]dibenzoic acid, bipy = 4,4′-bipyridine, bib = 1,4-bis(imidazol-1-yl)-butane), have been prepared under hydrothermal conditions. Their structure were determined by single-crystal X-ray diffraction analysis, and further characterized by elemental analysis, IR spectra TG, and powder X-ray diffraction analysis. Complexes 1 and 2 both exhibit two-dimensional network structures and the intermolecular hydrogen bonding, π-π stacking interactions extend them into 3D supramolecular architectures, which play an important role in stabilizing them. The solid-state luminescent property of 1 and 2 were characterized and the results revealed that they exhibit fascinating photoluminescence properties. In addition, the sensing property of only 1 has been examined briefly. The quantum-chemical calculations of complex 1 have been performed on ‘molecular fragments’ extracted from the crystal structure using the PBE0/LANL2DZ method built in Gaussian 16 Program.

Conventional ceramic sintering often requires high temperatures and hours of duration to achieve near full density. Herein, we adopted an innovative ultrafast high-temperature sintering (UHS) technique to densify several representative bulk oxides within an isothermal duration of 30 s and a total sintering period of several minutes, and revealed the relationship between ceramic structures and processing parameters. These achievements demonstrate the great potential of the UHS technique in the rapid densification of ceramics. Moreover, this flexible technique is expected to accelerate the material screening rate and facilitate the development of novel materials.

Poly(styrene-b-isobutylene-b-styrene) triblock copolymer (SIBS), a kind of thermoplastic elastomer with biocompatibility and biostability containing fully saturated soft segments, could be synthesized via living cationic copolymerization. A novel poly[(styrene-co-methylstyrene)-b-isobutylene-b-(styrene-co-methylstyrene)]-g-polytetrahydrofuran (M-SIBS-g-PTHF) block graft copolymer was prepared to increase the polarity and service temperature of SIBS by grafting polar PTHF segments onto SIBS. A series of the above block graft copolymers with average grafting numbers from 2 to 6 and molecular weights of PTHF branches ranging from 200 g·mol−1 to 4200 g·mol−1 were successfully synthesized via living cationic ring-opening polymerization of tetrahydrofuran (THF) coinitiated by AgClO4. The introduction of PTHF branches led to an obvious microphase separation due to thermodynamic incompatibility among the three kinds of segments of polyisobutylene (PIB), polystyrene (PS) and PTHF. Moreover, the microphase separation promotes the rearrangement of PTHF branches to form the nanocrystallization-locked physically cross-linked network after storage at room temperature for 2 months, leading to insolubility of the copolymers even in good solvents. The melting temperature and enthalpy of PTHF nanocrystallization locked in hard domains of M-SIBS-g5-PTHF-1.1k block graft copolymer increased remarkably up to 153 °C and 117.0 J·g−1 by 23 °C and 11.6 J·g−1 respectively after storage for long time. Storage modulus (G′) is higher than loss modulus (G″) of M-SIBS-g-PTHF block graft copolymer at temperatures ranging from 100 °C to 180 °C, which is much higher than those of the SIBS triblock copolymer. To the best of our knowledge, this is the first example of high performance M-SIBS-g-PTHF block graft copolymers containing segments of PIB, PS and PTHF with nanocrystallization-locked architecture.

An improved ultra-wideband metamaterial absorber (MA) with high absorptivity in the infrared region is proposed. It features a mixture of copper and GaAs at the top layer, which can greatly raise t...

To improve the dielectric performance of Ba(Zr0.2Ti0.8)O3-based ceramics, (1-x) Ba(Zr0.2Ti0.8)O3-xBi(Zn2/3Nb1/3)O3 composite ceramics (as short as (1-x) BZT20-xBZN) were synthesised using a solid-state reaction. The effects of Bi(Zn2/3Nb1/3)O3 on the microstructure and dielectric properties were studied. Stable cubic symmetry and polar nanoregions (PNRs)-related first-order Raman modes were observed as the amount of BZN increased. The 0.94BZT20–0.06BZN sample exhibited improved dielectric constants with a higher degree of relaxor behaviour (γ = 1.91). BZN-dependent dielectric nonlinearity was observed under an applied electric field. The evolution of the relaxor behaviour and dielectric nonlinearity in the (1-x) BZT20-xBZN composite ceramics were related to PNRs variations. The largest figure of merit (~65) was obtained for the 0.94BZT20–0.06BZN ceramics, while the dielectric tunability was 75%.

In the current study, thermal boundary conditions are considered in a rotating smooth channel with a square cross-section to investigate the secondary flow and compare it to that of the same channel without heating. The measurement is conducted at three streamwise planes (X=445 mm, 525 mm, 605 mm). The flow parameters are the Reynolds number (Re=4750, which was based on the average longitudinal or primary velocity U and the hydraulic diameter D of the channel cross-section), the rotation number (Ro=ΩD/U, where Ω is the rotational velocity, ranging from 0 to 0.26), and the aspect ratio of the channel cross-section (AR=1, which is calculated by dividing the channel height by the channel width). The leading and trailing walls are heated under a constant heat flux qw=380 W/m2, and the top and bottom walls are isothermal at room temperature. This work is in a series with our previous work without thermal boundary conditions. Based on the experimental data, we obtained a four-vortex regime. There is a counter-rotating vortex pair near the leading side and the trailing side. Because the leading and trailing walls are heated, the buoyancy force increases the relative vertical position of the vortex pair near the trailing side from 5% to 12.5% of the hydraulic diameter. When moving upstream along the streamwise direction, the upper vortex near the trailing wall becomes weaker, whereas the lower vortex becomes stronger. As the rotational speed increases, the vortex pair near the trailing side is inhibited by the Coriolis force. Under heated thermal boundary conditions, the vortex pair near the trailing side reappears due to the effect of buoyancy force. These results indicate that the buoyancy force has a substantial effect on the secondary flow regime under thermal boundary conditions.

In this study, a drop weight testing method was employed to investigate the impact bending behavior of ethylene vinyl acetate (EVA) modified engineered cementitious composite (ECC). The ECC with no EVA was selected as control, and the static and impact bending behavior was compared with the EVA modified ECC. The results showed that the compressive strength of EVA modified ECC decreased by 20%~30% in comparison with control ECC with fly ash substitution ratio variation. The addition of EVA can improve the bending toughness of ECC dramatically under static loading condition. As different from the static bending, the impact bending toughness of EVA modified ECC was smaller than that of control under impact loading condition. However, the degree of damage of EVA modified ECC was lower than control due to small crack width.

At high rotation numbers, the rotational effects on heat transfer and flow could be diverse among the channels with different blockage ratios. However, most studies are conducted under low rotation number (less than 0.25) and selected blockage ratio. This paper experimentally investigates the effect of rib blockage ratio (ranges from 0 to 0.3) on pressure loss and heat transfer in a rotating square channel under high rotation number (up to 0.81). The ribs staggered on leading and trailing walls were oriented 90° to the mainstream flow. The Reynolds number and the wall-to-fluid temperature ratio varied from 20 000 to 40 000 and 0.08 to 0.2, respectively. The results showed that a larger blockage ratio resulted in a better heat transfer but a higher pressure drop. The optimum blockage ratio was 0.1 for the best thermal performance. The rotational effects were weakened in the passage with a higher blockage ratio, where the critical rotation number could not be observed. Moreover, the heat transfer enhancement induced by rotation was more significant when the temperature ratio increased. Finally, the correlations were developed for the pressure drop and the convective heat transfer on the leading and trailing edges.

The conductivity and stability of materials have always been the main problems hindering the development of lithium-ion battery applications. Here, we successfully construct MnCO3@NiO composites with unique heterogeneous structure via the epitaxial growth of porous NiO nanosheets (thickness: ∼125 nm) on MnCO3 microspheres (diameter: ∼3 μm) to be the anode of lithium-ion batteries. The synergistic effect provided by this special heterogeneous structure effectively improves the electrochemical kinetics, specific surface area as well as structural stability of the composites, finally resulting in predictable enhanced comprehensive electrochemical performance. The electrochemical results show that the MnCO3@NiO composites exhibit a reversible discharge capacity of 624 mA h g−1 at a current density of 1.0 A g−1 up to 300 cycles.

For Bi0.5Na0.5TiO3-based complex oxides, a critical bottleneck is that a higher depolarization temperature Td is often obtained at the cost of sacrificing their piezoelectricity d33 (d33 ∝ 1/Td), which severely restricts the further development of this kind of promising material. Here, by combining compositional materials selection with rapid quenching in liquid nitrogen from ultra-high temperatures, we report an advance in simultaneously achieving a large d33 (232 ± 5 pC N−1) and a high Td (188 °C) in Bi0.5Na0.5TiO3-based complex oxides. In situ characterization indicates that the superior performance (232 pC N−1 < d33 < 281 pC N−1) can be maintained in a wide working temperature range (25 °C < T < 185 °C). A series of quenching treatments and multi-scale structural analyses (ion environment, lattice distortion and domain evolution) reveal that the increased coherence length (the size of unit cells sharing the same ferroelectric symmetry) of the ferroelectric lattice enhances the ferroelectric ordering and leads to the deferred Td. Theoretical simulations and experimental results validate the quenching-induced redistribution of A-site ions. And the resulting enhanced ferroelectric polarization compensates the degenerated dielectric response, accounting for the effectively increased Td without decreasing the superior piezoelectric response. This research provides a paradigm for designing high-performance Bi0.5Na0.5TiO3-based electromechanical materials in a wide working temperature range.

With the continuous increase of aerodynamic and thermal load, the endwall of modern gas turbines has become the critical region affected by the uncertainties in the manufacturing and operation process and thus is very likely to suffer performance degradation and thermal failure. Therefore, it is critical to understand and quantify the impacts of uncertainty factors on endwall aero-thermal performance. Based on Kriging surrogate, the frameworks of uncertainty quantification and global sensitivity analysis are constructed for a gas turbine blade endwall. The impacts of slot geometry deviations (slot width, endwall misalignment) and mainstream condition fluctuations (turbulence intensity, inlet flow angle) on endwall aero-thermal performance are quantified and analyzed. Results show that the actual performance of the endwall has a high probability of deviating from its nominal value. With respect to the nominal values, the maximum deviations of aerodynamic losses, averaged film cooling effectiveness and averaged Nusselt number reach up to 0.33%, 45% and 5.0%, respectively. The critical regions which are most sensitive to the input uncertainty parameters are identified. Furthermore, the inlet flow angle is proved to be the most significant parameter affecting the endwall aero-thermal performance through sensitivity analysis. The influence mechanisms of the inlet flow angle on endwall aero-thermal performance are clarified by detailed flow and thermal field analysis. Results show that the inlet flow angle significantly alters the size and strength of the secondary flow structures, resulting in a large variation of endwall aero-thermal performance. Quantitatively, a positive incidence angle of 2 degrees can lead to a 0.1% reduction of total pressure coefficient, a 12% reduction of averaged film cooling effectiveness and a 2% enhancement of averaged Nusselt number.

In this letter, we report the design and measurement of a 3D solenoid inductor that is embedded in a Si substrate and can integrate an iron core. Various inductor designs were fabricated with good structural integrity and repeatability via a CMOS-compatible MEMS fabrication process. The average inductance and quality factor peak-to-peak variation of the inductors was below 10%, which indicates that the fabrication process is repeatable. Among the inductors without iron cores, the highest quality factor (37.6 at 21 MHz) was found in a 5-turn inductor, and the highest inductance and inductance density (respectively, 86.6 nH and 21.7 nH/mm2) were found in a 20-turn inductor. Among the iron-core inductors, the 15-turn inductor had an inductance of 1063 nH and an inductance density of 354.3 nH/mm2, nearly 18 times higher than the same design without an iron core, which is the highest inductance density for a MEMS microinductor to the best of our knowledge. This type of inductor is an important component in RF MEMS and electromagnetic power MEMS devices and can improve their performance and efficiency.

The internal convective heat transfer characteristics of n-decane at supercritical pressure in a vertical square tube with a hydraulic diameter of 1.8 mm were experimentally investigated. The external wall temperatures of the square tube were measured with welded thermocouples whereas the internal wall temperatures were calculated with space marching method. In this experiment, the operating pressure ranged from 3 to 5 MPa and the heat flux from 100 to 500 kW/m2. Besides, the flow direction in the vertical tube was also switched in order to examine the effects of buoyancy. Moreover, the circumferential uniformity of heat transfer was also discussed. The results showed that the effects of buoyancy on the heat transfer were negligible once the local buoyancy number was less than a threshold. After the threshold, the buoyancy promoted the heat transfer in the downward flow configuration, but weakened the heat transfer in the upward flow one. The reason could be inferred that the buoyancy would influence the intensity of turbulent kinetic energy and the heat transfer near the wall. Finally, new heat transfer correlations for vertical upward and downward flow in square tubes were proposed.

The performance of the suction side tip region film cooling under rotating condition is investigated by numerical simulation methods in this paper. In the simulation, three classical types of tip structures, including flat tip, double squealer tip and single squealer tip, are chosen to investigate tip structure effects. The effects of blowing ratios, density ratios and rotating Reynolds numbers (Ro) are analyzed. The results showed that the film performance on the suction side tip region is mainly influenced by the tip leakage vortex and the passage vortex: the tip structure changes the flow field greatly. The leakage flow in the double squealer tip results attaches the suction side wall best. For high blowing ratio results one leg of the counter rotating vortex pair (CRVP) is compressed and swept off the wall. The other one is pushed onto the wall achieving the better film coverage. Similarly one leg of CRVP dominates the jet flow at the near hole exit region for low density coolant results. But for the downstream film cooling the low density coolant has better performance. Rotation changes the mainstream stricture. The passage vortex is strengthened as the Ro increases. So the film deflection becomes more and more obvious.

Numerical simulations of flow and heat transfer to supercritical RP-3 through the inclined tubes have been performed using LS k–ε model embedded in Fluent. The physical properties of RP-3 were obtained using the generalized corresponding state laws based on the four-component surrogate model. Mass flow rate is 0.3 g/s, system pressure is 3 MPa, inlet temperature is 373 K. Inclination of the inclined pipe varied from −90° to 90°, with heat flux varied from 300 kW/m2 to 400 kW/m2. Comparison between the calculated result and the experimental data indicates the range of error reasonable. The results of ±45° show that temperature inhomogeneity in inclined pipe produce the secondary flow in its cross section due to the buoyancy force. Depending on the strength of the temperature inhomogeneity, there will be two different forms of secondary flow and both contribute to the convective heat transfer in the pipe. The secondary flow intensity decreases when the inhomogeneity alleviates and thermal acceleration will play a leading role. It will have a greater impact on the turbulent flow to affect the convective heat transfer in the pipe. When changing the inclination, it affects the magnitude of the buoyant component in flow direction. The angle increases, the buoyancy component decreases. And the peak temperature of wall dominated by the secondary flow will move forward and increase in height. Keywords: Heat transfer, Hydrocarbon fuel, Inclined pipe, Supercritical pressure, Variable properties

The film cooling performance of the suction side of a turbine blade is experimentally and numerically investigated under the rotating condition. Experiments were performed on a 1.0-stage turbine. In the experiments, the effects of density ratio (0.96 and 1.52) and blowing ratio (0.2–1.0) were studied. The rotational effects were studied by comparing results of three mainstream rotating Reynolds numbers (3528, 4410 and 5292). Three hole positions of 1/4, 1/2 and 3/4 of the total blade height were set on three blades to confirm the mainstream influence. The jets of the holes at 1/4 and 3/4 of the blade height deflect to the mid-span of the blades. The film protection at both hole positions is damaged by the mainstream vortices, resulting in a lower cooling effectiveness. Moreover, as proven by the flow field, the passage vortex influence can be strengthened by the rotation. Thus, as the rotating Reynolds number increases the film cooling performance worsens. An optimal blowing ratio, 0.6, for the mid-span hole film cooling exists. Different from the flat plate film cooling, the film deflection occurs in the blade film cooling and decreases as the blowing ratio. At last, the high density ratio can improve the film cooling performance.

A reliable, highly efficient phototransistor would enable multifunctional photodetection and amplification and would also allow for electrical signal-readout processes. Lead halide perovskite semiconductors are known to generally have large mobilities and carrier lifetimes, which make them ideal candidates as photodetectors and for use in other electronics. Here, we demonstrate an infrared perovskite/MoS2 quantum dots’ (QDs) phototransistor with a quick detection speed ( $40~\mu \text{s}$ ), high detectivity ( ${5}\times {10}^{{11}}$ Jones) even at high frequencies ( $10^{{4}}$ Hz), reasonable linearity, and a wide spectrum response in infrared wavelengths. The realization of efficient infrared detection is due to the effective photo-induced charge between the perovskite/QDs’ interface, which is achieved by combining the modulation of the electrical gate and optical light. These results are advantageous for infrared perovskite phototransistors.

Transition-metal oxides are considered as promising anode materials because of the high theoretical specific capacities. However, the fast capacity fading and unstable cycling performance restricted their electrochemical performance. To achieve fast and stable lithium storage capability, in this work, bricklike Ca9Co12O28 is synthesized via a modified Pechini method with the assistance of the C12H25SO4Na surfactant. The as-obtained Ca9Co12O28 ternary oxides exhibit stable structural stability, which may be attributed to the in situ formed CaO layers during the first discharge process. When tested as an anode material in lithium-ion batteries (LIBs), bricklike Ca9Co12O28 exhibits an excellent reversible capacity of 517 mA h g–1 at 1 C after 200 cycles. Even at the high rate of 3 C, the discharge capacity can still reach 392 mA h g–1 after 200 cycles. It reveals a great application prospect in anode materials of LIBs.

An experimental investigation has been performed to investigate the effects of the rotation and blowing ratio on the film cooling effectiveness distributions of the leading-edge regions of a twist gas turbine blade using a thermochromic liquid crystal (TLC) technique. The experiments were carried out at three rotating speeds, including 400 rpm (positive incidence angle), 550 rpm (zero incidence angle), and 700 rpm (negative incidence angle). The averaged blowing ratio ranged from 0.5 to 2.0. CO2 was used as the coolant to ensure that the coolant-to-mainstream ratio was equal to 1.56. The Reynolds number, based on the mainstream velocity of the turbine outlet and the rotor blade chord length, was 6.08 × 104. The effects of the rotating speed and the blowing ratio were analyzed based on the film cooling effectiveness distribution. The results show that rotating speed plays an indispensable role in determining the film cooling effectiveness of distributions on the leading edge. The position of the stagnation line moves from the pressure side (PS) to the suction side (SS) via an increase in rotating speed. Under the same blowing ratio, the area-averaged film cooling effectiveness increases monotonously with an increase in rotating speed. Under the same rotating speed, the area-averaged film cooling effectiveness increases with the increase in blowing ratio. More details about the effects of the rotation speed and blowing ratio on the spanwise averaged film cooling effectiveness of the leading-edge region are shown in this study.

It is an urgency to find capable lead-free piezoelectric ceramics to show effort towards environmental protection. Bi0.5Na0.5TiO3 (BNT)-based piezoelectric ceramics is one of the most promising lead-free systems, for which compositional modification is an efficient way to enhance the piezoelectric performance. In this work, lead-free 0.82(Bi0.5Na0.5)TiO3-(0.18-x)BaTiO3-x(Bi0.5Na0.5)(Mn1/3Nb2/3)O3 ceramics were synthesized by a conventional solid state reaction method. Polarization and strain hysteresis loops implies a phase transition from FE (ferroelectric phase) to ER (ergodic relaxor). An electric field induced high strain of 0.28% occurred at x = 0.0275, which was attributed to the coexistence of FE and ER phases. It is considered that our work can help to understand the complex phenomenon observed in BNT-based lead-free system.

In order to conduct structural integrity assessment based on probabilistic fracture mechanics, the scatter in fatigue crack growth behavior of materials should be characterized accurately. In this work, ten groups of superalloy crack growth tests under the identical condition are conducted. Based on the statistic results of experimental data, there is a considerable degree of scatter in the fatigue crack growth behavior of GH420Li. The crack growth rates (da/dN) under the identical ΔK fit lognormal distribution. According to the random number generation principle of lognormally distributed variable, a stochastic crack growth model depending on the mean value and the coefficient of variation (COV) is derived. As the mean value and COV of ln(da/dN) can be expressed as functions of ΔK, the stochastic crack growth rate is determined by ΔK and a standard normally distributed random variable. At last, the stochastic model is adopted to calculate the fatigue crack growth of CT specimen. The comparison of the predicted results with the experimental results proves the effectiveness of the proposed model.

For perovskite ferroelectric oxides, the composition-induced transition from ferroelectrics to relaxors can enhance their electrostrictive coefficient Q33 remarkably, and has been attracting more and more attention in recent years. Achieving a larger electro-strain response is one of the most original driving forces for pursuing higher Q33 values, while the two are often incompatible. Herein, taking the promising relaxor ferroelectric Na0.5Bi0.5TiO3 (NBT) as the research object, we report the excellent electrostriction-like electro-strain behaviors (0.41% ≤ Suni ≤ 0.46%, 25 ≤ T ≤ 125 °C; Suni exhibits only 2.23% decline after 105 cycles) together with a series of enhanced Q33 values (0.029–0.047 m4 C−2). Accompanied by the reconstruction of de-coupled A–O interactions, the electric-field-induced relaxor to ferroelectric state transition contributes to the superior electro-strain behaviors, while the enhanced Q33 will greatly degenerate during this transition process. In contrast to the non-hysteretic electrostriction observed in linear dielectrics, for NBT-based relaxor ferroelectrics, the peculiar coexistence of ferroelectric in-phase a0a0c+ and anti-phase a−a−a− tiltings is suggested to contribute to the enhanced electrostriction-like behaviors observed in this work. These observations indicate that NBT-based systems can be considered as a potential family of peculiar lead-free electrostrictors for application in the field of actuators.

Experimental investigations were performed to study the effects of the injection angle of cylindrical holes and the blowing ratio on the leading-edge-region film cooling of a twisted turbine blade under rotating conditions. The experiments were carried out at a test facility with a 1-stage turbine using the thermochromic liquid crystal (TLC) technique. All experiments were performed at a rotating speed of 574 rpm with an average blowing ratio ranging from 0.5 to 2.0. The Reynolds number was fixed at 6.3378 × 104 based on the mainstream velocity of the turbine outlet and the rotor blade chord length. CO2 was used as the coolant to achieve a coolant-to-mainstream density ratio of 1.56. The film-hole injection angles tested were 30°, 45° and 60°. The results show that both the injection angle and the blowing ratio have significant impacts on film cooling effectiveness. For α = 30° and α = 45°, the radial average film cooling effectiveness increases as the blowing ratio increases in all regions. For α = 60°, this effectiveness first increases and then decreases as the blowing ratio increases, with the case of M = 1.5 yielding the best average cooling performance. At each blowing ratio, the α = 30° case always yields the highest streamwise average film cooling effectiveness in the region of −4.3

This paper reports on an experimental investigation of the influences of mainstream Reynolds number and coolant density on film cooling characteristics on the leading edge of a twisted turbine blade under rotational conditions. The experiments were carried out at a test facility with a 1-stage turbine using the thermochromic liquid crystal (TLC) technique. The mainstream Reynolds number varied from 4.4201 × 104 to 7.1797 × 104. All tests were carried out at three rotational speeds of 400 r/min, 500 r/min and 650 r/min to fix the rotation number at 0.0018. The coolant-to-mainstream density ratios were fixed at 1.04 and 1.56 with N2 and CO2 as coolants, respectively. The blowing ratio effect was also considered. The results showed that under the same blowing ratio, the averaged film cooling effectiveness on the measurement area increased with increasing mainstream Reynolds number for both coolant gases. Under the same Reynolds number, the span-wise averaged film cooling effectiveness increased as the blowing ratio increased for both coolant gases. Under the same Reynolds number and blowing ratio, higher-density coolant jets (CO2) provided higher averaged film cooling effectiveness than lower-density coolant jets (N2) on the measurement area. Overall, mainstream Reynolds number, blowing ratio and coolant density played significant roles in the film cooling characteristics of the leading edge under rotational conditions.

Operational stability and sensitivity are key issues in the practical application thin film transistor (TFT) of sensors, and the interdigital electrode is an important element that can be applied to TFT. In this study, a completely transparent interdigital electrode was printed on the glass plated with indium tin oxide (ITO) material using a laser etching machine. The produced interdigital electrode has the characteristics of high density, small line spacing, high sensitivity, and laser etching can be large. The amplitude reduces the production time of the device. Use a semiconductor tester to test the electrical transfer characteristics of the interdigital electrodes. The photoelectric generation spectrum and absorption spectrum of the interdigital electrode array plated with indium gallium zinc oxide (IGZO) material were tested. After plated with IGZO material, the ability to absorb light was greatly enhanced. The interdigital electrodes plated with IGZO material can be applied to the driving and test circuits of flexible wearable spectroscopic industrial detection sensors. It can amplify the circuit signal. After being plated with IGZO material, the power consumption of the circuit can be greatly reduced, and the measurement with low power consumption, high stability and high accuracy can be realized.

The nitrogen doping/infusion of 650 MHz cavities for the circular electron positron collider (CEPC) is investigated in this study. Two 650 MHz 1-cell cavities are first treated via buffered chemical polishing (BCP), followed by nitrogen doping. A “2/6” condition is adopted, similar to that for 1.3 GHz cavities of Linear Coherent Light Source II. The quality factor of both cavities improved to 7 × 1010 in low fields, i.e., higher than that obtained from the baseline test. One 650 MHz two-cell cavity is nitrogen infused at 165 °C for 48 h with a BCP surface base. The intrinsic quality factor (Q0) reached 6 × 1010 at 22 MV/m in the vertical test, and the maximum gradient is 25 MV/m, which exceeds the specification of the CEPC (4 × 1010 at 22 MV/m).

Previously-reported electromagnetic (EM) linear micromotors typically applied meander coils or planar spiral coils because there are many difficulties in solenoid coil fabrication using integrated micro electro-mechanical system (MEMS) technologies. However, solenoid microcoils with iron cores have a higher inductance density and a lower leakage magnetic flux than planar coils. In this study, a MEMS voice coil motor (VCM) with a 3D solenoid voice coil was designed., fabricated and tested. The VCM was comprised by a voice coil fabricated using MEMS processes as the traveler and a combination of two permanent magnets (PMs) and an E-shape silicon-steel core which was inserted into the voice coil as the stator. The copper voice coil in silicon substrate was a solenoid-shape coil of high aspect ratio (coil height was 1.4 mm and line width was 0.1 mm). The coil was embedded tightly in the silicon substrate, resulting in a good heat dissipation performance and thus a high current-carrying capacity. The VCM weighed 0.07 g with a size of approximately 4 mm x 2.5 mm x 4 mm before circuit connection. The testing results showed that the effective travelling distance of the traveler was 1 mm with stable thrust force of approximately 3.9 mN/A and the motor vibrated stably when a 50 Hz square-wave current of 0.5 A was applied. This MEMS VCM has low weight and high thrust force, which has bright application prospects in micro actuators.

In the paper, tunable Ba 0.5 Sr 0.5 TiO 3 (BST) varactors on LiNbO 3 substrates were investigated by changing electricity and stress fields applied to the BST varactors. The BST films were fabricated by RF Magnetron Sputtering on LiNbO 3 substrates and the XRD of films showed high crystal quality on (110) surface. We demonstrate that the capacitance tunability can each 1.67 under applied DC voltage from 0 to 8V. Additionally, the tunability can be 1.46 by changing stress from 0 to 7. 2MPa. Interestingly, the tunability is 2.45 under the combinations of electricity and stress fields. This phenomenon implies that the applied dynamic stress can break restrictions in the limitation of the capacitance tunability of this thin film. It is of great significance to observe the direct relationship between the change of strain and dielectric tunability caused by stress fields, which can provide more ideas for the design of thin films varactors in future applications, such as tunable SAW filter, microwave delay line and acoustic stress sensor, etc.

A non-Newtonian thermal elastohydrodynamic lubrication (TEHL) model for the elliptic contact is established, into which the inertia forces of the lubricant is incorporated. In doing so, the film pressure and film temperature are solved using the associated equations. Meanwhile, the elastic deformation is calculated with the discrete convolution and fast Fourier transform (DC-FFT) method. A film thickness experiment is conducted to validate the TEHL model considering the inertia forces. Further, effects of the inertia forces on the TEHL performances are studied at different operation conditions. The results show that when the inertia forces are considered, the central and minimum film thicknesses increase and film temperature near the inlet increases obviously. Moreover, the inertial solution of the central film thickness is closer to the experimental result compared with its inertialess value.

Mask-free direct printing can alleviate the high cost and high consumption involved in photo-lithography for chip processing. Most of their technical routes are based on the traditional short focal length nozzles, which is suffered from higher probability of nozzle retardation or clogging as well as the higher mechanical burdens. While aerosol-assisted chemical vapor deposition (AACVD) has better deposition adaptability but usually lack of focused printing. In this study, a system that combines of long focal length ALS with AACVD, so called AAFCVD printing system has been developed. The single-point printing capability and aerosol precursor adaptability were verified, and the relationship between the single spot printing performance and the chemical reaction mechanisms were studied. Furthermore, a unique carbon injection effect brought by ALS was discovered. Finally, the linear graphics printing performances of the system were evaluated. This system is expected to become a new generation of high-performance mask-free printing system for chip manufacturing.

Zinc oxide (ZnO) has drawn much attention due to its excellent optical and electrical properties. In this study, ZnO film was prepared by a high-deposition-rate spatial atomic layer deposition (ALD) and subjected to a post-annealing process to suppress the intrinsic defects and improve the crystallinity and film properties. The results show that the film thickness increases with annealing temperature owing to the increment of oxide layer caused by the suppression of oxygen vacancy defects as indicated by the X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) spectra. The film transmittance is seldom influenced by annealing. The refractive index increases with annealing temperature at 300&ndash, 700 &deg, C, possibly due to higher density and crystallinity of the film. The band gap decreases after annealing, which should be ascribed to the decrease in carrier concentration according to Burstein&ndash, Moss model. The carrier concentration decreases with increasing annealing temperature at 300&ndash, C since the oxygen vacancy defects are suppressed, then it increases at 800 &deg, C possibly due to the out-diffusion of oxygen atoms from the film. Meanwhile, the carrier mobility increases with temperature due to higher crystallinity and larger crystallite size. The film resistivity increases at 300&ndash, C then decreases at 800 &deg, C, which should be ascribed primarily to the variation of carrier concentration.

Magnetoelectric memories exhibit the advantages of FRAMs and MRAMs. We report the fabrication of a magnetoelectric memory cell consists of microsized Fe70Ga30 films on ferroelectric 50 [Ba(Zr 0.2 Ti 0.8 )O 3 ]-50(Ba 0.7 Ca 0.3 TiO 3 ) (50BZT-50BCT) films on Pt/Ti/SiO 2 /Si substrates. The 50BZT-50BCT films were sputtered by RF magnetron sputtering, ferroelectric hysteresis loop and displacement voltage butterfly loop were characterized which suggest that 50BZT-50BCT thin films exhibit good ferroelectric and piezoelectric properties. Fe 70 Ga 30 films were grown on 50BZT-50BCT films by DC magnetron sputtering deposition combined with photolithography and results indicate that 50BZT-50BCT/Fe 70 Ga 30 composite films have good soft magnetic properties with a coercive field of 50 Gauss at room temperature. The microstructure of the composite films were characterized by X-ray diffraction. The current voltage behaviors of the microsized Fe70Ga30 films were measured, the current voltage curves could be modulated effectively by applying bias electric field, and multilevel resistance states could be induced, and thus a magnetoelectric memory device was obtained which uses electric field as writing field and the resistance of the ferromagnetic layer as the media.

Perovskite semiconductors have attracted intensely advancing researches in optical devices, due to the long diffusion length, high quantum efficiency and excellent light absorption coefficients and so on. Especially combined with Quantum dots (QDs), this blended semiconductor can be selected as the alternative candidate for the photosensing core of the sensors and other optoelectronics. To realize the incident light-to-electric converting and directly signal’s reading-out, we have put enormous efforts to design and fabricate a versatile phototransistor. The optimal device’s structure also balances the electrical and optical performances to enable enhancing the photodetecting efficiency and compatibility. In this report we reviewed realizations, models, physics and metrology applications of perovskite and perovskite QDs based phototransistor. In our research group, we have designed the phototransistors with QDs as sensing core by nano-manufacturing technology and explored the photo-generation mechanism. The corresponding protocols focus on understanding of connection between these different structures and photodecting performances. The subsequent optimized studies advance technologies for integrated photodetecting applications with potentially inorganic nano-scale optical materials.

In this work, we report on fabrication of a solar blind phototransistor based on ZnO Nanorods (NRs) integrated into InGaZnO4 (IGZO) substrate to obtain highly sensitive UV detection in solar blind spectrum. Highly efficient solar-blind UV detection can be demonstrated in this phototransistor with the photo-responsivity (R) of 1.9 × 105 A/W, quantum efficiency (EQE) of 8.7 × 107%, photo-sensitivity of ∼9.5 × 105 and photo-detectivity of ∼8.12 × 1016 Jones, respectively, irradiated with the 280 nm incident light. The results imply that ZnO NRs/IGZO phototransistor with laser annealing is a promising candidate for the development of highly sensitive solar-blind photodetector.

In this paper, we experimentally investigated the effect of turbulent intensity on heat transfer in a square rotating channel. The grid generated turbulence is measured by hot-wire, and the heat transfer coefficient is measured by TLCs. In the experiment, the Reynolds number, based on the channel hydraulic diameter ( D = 80 mm ) and the bulk mean velocity ( V m = 1.82 m / s ), is 10,000, and the rotation number ranges from 0 to 0.52. The mean density ratio ( d . r . = ( T w - T b ) / T w ) is about 0.1 in the current work using transparent heater glass (Indium Tin Oxide) to provide uniform heat flux. Two different turbulent intensity of inlet air (0.6% and 5.5%) are taken into consideration to investigate the heat transfer distribution on the leading and trailing side. The results show that turbulent intensity has an effect on heat transfer on both leading and trailing side, especially at rotating conditions. At static conditions, the effect of turbulent intensity on heat transfer is not obvious. However, with the increase of rotation number, in case B with a medium turbulent intensity (Tu) of 5.5%, the Nu/Nu0 is about 10% higher than that in the case A with low turbulent intensity of 0.6% with the rotation number of 0.52 at X/D = 2 on trailing side. The enhancement of case B decreases along X/D directions. On the leading side, the turbulent intensity has same effect on heat transfer with that on trailing side, but not as prominent as that on the trailing side. In current work, the turbulent intensities at different X/D directions are also presented to explain the phenomenon of heat transfer in the channel. More detail of results will be presented in this paper.

The integration of ferroelectric and ferromagnetic promises an essential strategy of obtaining high performance electronic devices. In this work, we demonstrate in situ observation of electric field induced magnetic domain structure evolution for 0.5Ba(Ti0.8Zr0.2)O3–0.5(Ba0.7Ca0.3)TiO3–CoFe2O4 (BZT–0.5BCT/CFO) films, which manifests the magnetoelectric (ME) coupling between ferroelectric BZT–0.5BCT and ferrimagnetic CFO. The multiferroic behaviors of BZT–0.5BCT/CFO bilayers thin films were characterized by measuring ferroelectric domains, ferroelectric and ferrimagnetic hysteresis loops. The magnetic domain structure were investigated as functions of electric field, when the sample is applied with a voltage of 3 V, approximately 49.2% of the magnetization domain was varied in CFO thin films. The modulation of the domain structure could be attributed to the strain-induced mechanical transduction between the ferroelectric and magnetic films and modulation of the electron density of the CFO films. Direct observation of electric field induced magnetic domain evolution is significant since it gives a direct evidence of magnetoelectric coupling effect.

In order to test the effect of flame inhibitor on the secondary flame of propellant gas accurately and conveniently, and study the effect of flame inhibitor on the muzzle flame, an experimental method for evaluating the effectiveness of the flame inhibitor is designed with applying the flame simulator, high speed video camera and Pro Plus Image software. The duration time of flame, maximum flame area, total area of flame and q value of five kinds of charges containing flame inhibitor (TEGDN propellant with 0 wt% KNO3, 0.3 wt% KNO3, 1 wt% KNO3 in formulation or added bag with 1 wt% KNO3, 4 wt% KNO3) were studied through the designed method. It is showed that the TEGDN propellant contains 1wt% KNO3 in formulation had the best test result. The experimental results are consistent with the actual results of the interior ballistic firing, which shows that the method is feasible.

International audience; Drop-on-demand inkjet printing relies on the dispensing and precise positioning of very small amount of liquid on substrate before its transformation to a solid. Consequently, many steps are involved during inkjet printing process that must be understood to fabricate accurate patterns. In this work, multicomponent colloidal mixture spreading and drying is investigated. A systematic study has been performed to explain the impact of the jetting frequency, the drop spacing and the substrate exposure to UV ozone on a colloidal silver ink behavior. It is demonstrated that phase separation between stabilizing agent and colloids can occur during the spreading step. This phenomenon is described and appears to be related to the colloidal nature of the ink. It is shown that it can have a negative impact on patterns accuracy and several routes are given to overcome these issues.

Transient heat transfer measurement by Thermochromic Liquid Crystal (TLC) is applied in this paper to investigate heat transfer characteristics of the nozzle endwall with full coverage film cooling. The endwall heat transfer coefficient (h) with different blowing ratios (M) ranging from 0.7 to 4.0 at a constant mainstream Reynolds Number 1.63 × 10 5 is measured and analysed. The experiment results show that the heat transfer characteristics of the endwall are significantly affected by the film cooling. However, this effect changes with blowing ratio and varies in different regions of the endwall. At low M ( M = 0.7 ), coolant jets get into the boundary layer of the secondary flow, and enhance heat transfer, but lead to highly uneven h on the endwall. With the increase of M, coolant jets start to detach from the endwall while the turbulent mixing begins to enhance the heat transfer of the endwall downstream. Therefore h on the endwall first decreases and then increases with M. However, different turning points (the cases of M = 1 or M = 1.5) and increasing trends with M (staying constant or increasing monotonically) appear in different regions of the endwall.

Thermal diffusion of CO adsorbed on rutile TiO2(110) was studied in the 20–110 K range using photon-stimulated desorption (PSD), temperature-programmed desorption (TPD), and scanning tunneling microscopy. During UV irradiation, CO desorbs from certain photoactive sites (e.g., oxygen vacancies). This phenomenon was exploited to study CO thermal diffusion in three steps: first, empty these sites during a first irradiation cycle, then replenish them with CO during annealing, and finally probe the active site occupancy in the second PSD cycle. The PSD and TPD experiments show that the CO diffusion rate correlates with the CO adsorption energy—stronger binding corresponds to slower diffusion. Increasing the CO coverage from 0.06 to 0.44 monolayer (ML) or hydroxylation of the surface decreases the CO binding and increases the CO diffusion rate. Relative to the reduced surface, the CO adsorption energy increases and the diffusion decreases on the oxidized surface. The CO diffusion kinetics can be modeled satisfa...

Accepted for publication in a forthcoming issue of International Journal of Heat and Mass Transfer.

At supercritical pressure, due to the drastic change of thermophysical property near the pseudo-critical temperature, the density fluctuation and density variation, along with buoyancy, play an important role in supercritical turbulence modelling. Based on the original LS (Launder–Sharma) low-Reynolds number turbulence model, the buoyancy modification, the density fluctuation modification, the density variation modification and the empirical coefficients modification are considered and the corresponding correction terms are derived and applied in the governing equations. Numerical simulation of heat transfer to hydrocarbon fuel flowing through the uniformly heated round pipe at supercritical pressure has been performed by the modified LS turbulence model incorporated into the in-house numerical code. Inlet temperature varied from 373 K to 473 K, with heat flux varying from 241 kW/m2 to 470 kW/m2. Inlet mass flux was 736 kg/(m2⋅s) and operating pressure was 4 MPa. The flow directions included upflow and downflow. Compared with the original LS turbulence model, the modified LS turbulence model leads to the better agreement with the experimental results, with 41.16% improvement in computation accuracy in the current study. The consideration of density fluctuation and density variation effects makes the turbulence model more suitable for thermophysical property variation at supercritical pressure.

Pyrolysis of hydrocarbon fuel plays an important role in the regenerative cooling process. In this article, a Two-Dimensional (2D) numerical model is proposed to investigate the pyrolysis effects on the heat transfer characteristics and flow resistance of n-decane under supercritical pressure. The one-step global pyrolytic reaction mechanism consisting of 19 species is adopted to simulate the pyrolysis process of n-decane. The thermophysical and transport properties of the fluid mixture are computed and incorporated into the numerical model for simulation. Comparisons between the current predictions and the open published experimental data are carried out and good agreement is achieved. In order to better understand the complicated physicochemical process, further investigations on the turbulent flow and heat transfer coupled with pyrolysis in a tube have been performed under various operating conditions. The results indicate that the pyrolysis intensively takes place in the high fluid temperature region. The occurrence of the heat transfer deterioration would lead to increasing n-decane conversion at the beginning of the heated section. It is found that the pyrolysis could improve the heat transfer deterioration and promote the heat transfer enhancement. Meanwhile, pyrolysis gives rise to an abrupt increase of flow resistance. The mechanisms of the physicochemical phenomena are also analyzed in a systematic manner, which would be very helpful in the development of the regenerative cooling technology. Keywords: n-Decane, Convective heat transfer, Flow resistance, Pyrolysis, Supercritical pressure

This article presented a numerical investigation of supercritical heat transfer of the hydrocarbon fuel in a series of horizontal tubes with different diameters. The Reynolds averaging equations of mass, momentum and energy with the LS low-Reynolds number turbulence model have been solved using the pressure-based segregated solver based on the finite volume method. For the purpose of comparison, a four-species surrogate model and a ten-species surrogate model of the aviation kerosene RP-3 (Rocket Propellant 3) were tested against the published experimental data. In the current study, the tube diameter varied from 2 mm to 10 mm and the pressure was 3 MPa with heat flux to mass flux ratios ranging from 0.25 to 0.71 kJ/kg. It was found that the buoyancy has significant effect on the wall temperature non-uniformity in the horizontal tube. With the increase of the diameter, the buoyancy effect enhances and the thermal-induced acceleration effect reduces. The buoyancy effect makes wall temperature at the top and bottom generatrices of the horizontal tube increase and decrease, respectively. Due to the coupled effect of the buoyancy and thermal-induced acceleration caused by the significant change of the properties, as the diameter increases, the heat transfer deteriorates dramatically at the top generatrix but remains almost unchanged at the bottom generatrix at high heat flux to mass flux ratio. Heat transfer enhancement is observed at low heat flux to mass flux ratio when the tube diameter is less than 6 mm. Moreover, the safety analysis has been performed in order to optimally design the supercritical cooling system.

Behaviors of surface plasmon resonance (SPR) of a graphene-based Au aperture antenna are investigated in visible and near-infrared (vis-NIR) regions. Compared with the SPR wavelength of a traditional Au aperture antenna, the SPR wavelength of the graphene-based Au aperture antenna shows a remarkable blue shift due to the redistribution of the electric field in the proposed structure. The electric field of the graphene-based Au aperture antenna is highly localized on the surface of the graphene in the aperture and redistributed to be a standing wave. Moreover, the SPR of a graphene-based Au aperture antenna is sensitive to the thickness and the refractive index of the dielectric layer, the graphene Fermi energy, the refractive index of the environment and the polarization direction of the incident light. Finally, we find the wavelength, intensity and phase of the reflected light of the graphene-based Au aperture antenna array can be actively modulated by varying the graphene Fermi energy. The proposed structure provides a promising platform for realizing a tunable optical filter, a highly sensitive refractive index sensor, and other actively tunable optical and optoelectronic devices.

The heat transfer in a novel smooth wedge-shaped cooling channel with lateral ejection of turbine blade trailing edge is experimentally investigated in both non-rotating and rotating cases. Beside the conventional inlet at the bottom of the channel, an extra coolant injection from 8 lateral non-equant holes is introduced to improve the overall heat transfer. The total mass flow rate ratio (lateral mass flow rate/total mass flow rate) varies from 0 to 1.0. The major inlet Reynolds number and rotation number respectively vary from 10000 to 20000 and from 0 to 1.16. Experimental results show that the lateral inlet decreases local bulk temperature and increases local heat transfer at the middle and the top of the static channel. In rotating cases, the lateral inlet notably improves the heat transfer at the high-radius half channel and compensates the negative effects induced by the rotation. Both intensity and uniformity of heat transfer inside the channel are enhanced while flow resistance decreases with proper mass flow rate ratio of coolant from two inlets. The most satisfactory total mass flow rate ratio is around 2/3. This new structural style of cooling channel has huge potential and provides new direction of heat transfer of turbine blade trailing edge. Keywords: Heat transfer, Lateral inlet, Rotor blades trailing edge, Rotating, Wedge-shaped channel