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Unsuccessful prediction of particle tribocharging in tribocharger is partly due to the complexity of tribocharging process. In this work, computational fluid dynamics-discrete element method (CFD-DEM) modeling approach has been used to investigate particle charge in a cyclone tribocharger. Then particle image velocimetry (PIV) method is used to calculate the particle charge-to-mass ratio. The CaCO3 particle charge in a cyclone tribocharger is simulated and predicted under different gas velocities, particle sizes and moving distances. The simulation results carry out the quantitative and qualitative relationship between different parameters. At the same time, the charge-to-mass ratio between the particle simulation and the experimental results under different gas velocities is compared, and the results are all in the magnitude of 10−4. Experimental results in terms of particle charge-to-mass ratio are thus obtained. The CFD-DEM model is verified by comparison with the experimental results

The double-disc straight-groove (DDSG) grinding method is a new precision machining approach employed for the rolling surface of bearing rollers. The friction coefficient and wear resistance of grinding disc materials affect the grinding performance due to the operation on the workpiece. However, relevant research on DDSG is rather limited currently. Therefore, we analyzed the friction principles of the DDSG method and conducted friction and wear experiments to facilitate appropriate material selection for grinding discs. The optimal friction conditions for grinding disc materials were determined to ensure steady rotation of cylindrical rollers. In addition, the friction coefficients, wear resistance, and clogging resistance of various materials such as PTFE, PMMA, cast iron, brass, and fixed abrasives were measured by friction and wear experiments under grinding conditions. The friction pairs of PMMA-AISI 52100 and PTFE-AISI 52100 exhibited sliding friction coefficients of 0.14 and 0.03, respectively, along with a high grinding efficiency and excellent wear resistance. The friction pairs of both bearing steel-fixed abrasive and bearing steel-brass were easily clogged, leading to dramatic changes in the sliding friction coefficients, and neither fixed abrasive nor brass was found to be a suitable material for grinding discs. Thus, PMMA and PTFE were selected as the materials for upper and lower grinding discs. Moreover, a verification platform was built to implement the DDSG grinding method where a continuous rotation of ground roller was observed. Overall, this study provides a basis for feasible material selection and an appropriate material combination for designing a grinding machine based on DDSG.

To overcome the mandatory requirement of nozzle conductivity in the conventional electrohydrodynamic (EHD) jet printing, this paper proposed a self-induced electric-field-driven jet printing for fa...

A bulk pure Al sample was prepared through cold spray-friction stir processing composite additive manufacturing (CFAM). The microstructure is uniform, and consists of fine and equiaxed recrystallized grains with an average grain size of 4.4 μm. Continuous and discontinuous dynamic recrystallizations are primary recrystallization mechanisms. The ultimate tensile strength and elongation are 87 MPa and 60.3%, respectively, with the fracture mode being ductile. The order of contribution of strengthening mechanisms for the CFAM sample, from highest to lowest, is fine grain strengthening, dislocation strengthening, and grain orientation strengthening.

Tight oil is widely distributed around the world, and industrialized exploitation has been developed and applied in North America, greatly alleviating the contradiction between supply and demand of energy. The main storage space of tight oil reservoirs is micro-nano pores, and a reliable method for studying the occurrence of tight oil in micro-nano pores has not been studied. In this paper, the microscopic occurrence of tight oils in the Songliao Basin, Ordos Basin, and Tarim Basin in China are studied in combination with nuclear magnetic resonance (NMR) and field emission scanning electron microscopy (FE-SEM) scanning techniques. A method for characterizing the storage space, occurrence state, and influencing factors of tight oil based on SEM and NMR was proposed. The results show that the storage space of tight oil reservoirs is nanoscale cracks and pores. Mainly, these are distributed on the scale of less than 1 μm and more than 10 μm, the volume of porecracks is less than 1 μm, which account for more than 80% of the total volume. This indicates that the tight oil mainly exists in the nanoscale pore throat. The scattered distribution of crude oil in the black shape of oil spot is mainly in the micro-nano pores, and the crude oil content in the micro-cracks is small, indicating that nanoscale cracks are the main space for the occurrence of tight oil. However, some micro-cracks can penetrate oil spots or oil stains, and can connect the oil spots with scattered distribution, which will greatly improve the mobility of crude oil. In addition, oil spot accumulation areas often develop illite and illite/smectite mixed-layer, and clay minerals have developed nanoscale pores. The crude oil and clay minerals have certain associated characteristics. This study is of great significance for understanding the law of the occurrence and migration of tight oil and the basic theoretical research and technological innovation of the development of tight oil reservoir.

Li4Ti5O12/C anode material for lithium-ion batteries were successfully synthesized by two-step calcination and sol-gel method using tetrabutyl titanate, lithium acetate, citric acid, and β-cyclodextrin as starting materials. The microstructure and morphology of the materials were characterized by X-ray diffractometer, scanning electron microscope, and transmission electron microscope. The electrochemical properties of the materials were conducted by constant current charge-discharge test, AC impedance, and cyclic voltammetry. The results show that the prepared Li4Ti5O12/C composites are spinel cubic crystal with good crystallinity and without other impurities. The particle size is between 50 and 200 nm. The electrochemical properties of Li4Ti5O12 are effectively improved by carbon coating. Among these composites, Li4Ti5O12 with 5% carbon coating shows the initial discharge specific capacity of 167.1 mAh/g at 5C and a 93.3% capacity retention after100 cycles. Its reversible capacity remains 125.4 mAh/g after100 cycles at a high charge-discharge rate of 20 C.

To improve the snow-melting efficiency of the heated bridge deck for snow-melting, the insulated-conductive composite structure is proposed. It consists of the thermally conductive layer, the heating cable, the asbestos belt, and the reinforced concrete leveling course. The thermally conductive layer is proposed to replace the waterproof and cohesive layer in the traditional bridge deck. The material of the thermally conductive layer is thermally conductive cement-based composite, and it is helpful for heat transfer efficiency. Additionally, a 3D finite element heated bridge deck for snow-melting model, which was verified by field experiment, is developed to simulate the heating process of the heated bridge deck for snow-melting. According to the simulation results, the influences of insulated-conductive composite structure on the surface temperature and the damage of heated bridge deck for snow-melting were analyzed. Meanwhile, to consider both the surface temperature and damage, the structure evaluation method is proposed to recommend the optimal insulated-conductive composite structure. It can better guide the design and analysis of the heated bridge deck for snow-melting.

A new metal foam magneto-rheological (MR) fluid damper is optimized, and the mechanical performance is investigated experimentally. With a magnetic field, MR fluid is extracted from the metal foam and fills up the shear gap to produce the MR effect. The magnetic field density in the shear gap and the structural parameters are taken as the optimization object, and the optimal parameters of the metal foam MR fluid damper are updated. A testing system, including a DC motor with a speed controller, a force sensor with an amplifier and a power supply, is built to investigate the shear force of the metal foam MR fluid damper. The test signals are gathered and processed by a DAQ and a PC with LabVIEW software. A timer is designed to synchronize the start of the magnetic field. The experimental results show that the shear force decreases as the shear rate increases, and for the same shear rate, when the current ranges from 0.5 to 1.0 A, the difference of the shear force in the metal foam MR fluid damper is the most obvious. Additionally, the shear force after optimization clearly increases. When the current increases gradually, the shear force also increases. When the excited current increases from 0.5 to 1.5 A, as the current increases, the shear force increases obviously; however, once the current is above 1.5 A, the increase of the shear force is no longer obvious. In addition, for a shear rate of 2 s−1 and a current of 1.0 A, the shear force of the metal foam MR fluid damper is improved by a factor of 1.46 compared to the value before optimization.

Magnesium (Mg) and its alloys have attached more and more attention because of their potential as a new type of biodegradable metal materials. In this work, AZ31/ZrO2 nanocomposites with good uniformity were prepared successfully by friction stir processing (FSP). The scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to characterize the microstructure of the composites. The mechanical properties, electrochemical corrosion properties and biological properties were evaluated. In addition, the effect of reinforced particles (ZrO2) on the microstructure and properties of the composite was studied comparing with FSP AZ31 Mg alloy. The results show that compared with the base metal (BM), the AZ31/ZrO2 composite material achieves homogenization, densification, and grain refinement after FSP. The combination of dynamic recrystallization and ZrO2 particles leads to grain refinement of Mg alloy, and the average grain size of AZ31/ZrO2 composites is 3.2 μm. After FSP, the c-axis of grain is deflected under the compression stress of shoulder and the shear stress of pin. The ultimate tensile strength (UTS) and yield strength (YS) of BM were 283 and 137 MPa, respectively, the UTS and YS of AZ31/ZrO2 composites were 427 and 217 MPa, respectively. The grain refinement and Orowan strengthening are the major strengthening mechanisms. Moreover, the corrosion resistance in simulated body fluid of Mg alloy is improved by grain refinement and the barrier effect of ZrO2.

To explore the origin of magnetism, the effect of light Cu-doping on ferromagnetic and photoluminescence properties of ZnO nanocrystals was investigated. These Cu-doped ZnO nanocrystals were prepared using a facile solution method. The Cu2+ and Cu+ ions were incorporated into Zn sites, as revealed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). At the Cu concentration of 0.25 at.%, the saturated magnetization reached the maximum and then decreased with increasing Cu concentration. With increasing Cu concentration, the photoluminescence (PL) spectroscopy indicated the distribution of VO+ and VO++ vacancies nearly unchanged. These results indicate that Cu ions can enhance the long-range ferromagnetic ordering at an ultralow concentration, but antiferromagnetic &ldquo, Cu+-Vo-Cu2+&rdquo, couples may also be generated, even at a very low Cu-doping concentration.

In order to study the internal damage of the measured continuous casting shell, locate the internal defect position of the continuous casting shell and judge the defect size, this paper selects the continuous casting billet after the secondary cooling zone for defect detection, at this time, the thickness of the continuous casting shell is about 30mm. Using the finite element simulation software COMSOL, a multiphysical model of the electromagnetic ultrasonic transducer (EMAT) composed of a cylindrical permanent magnet and two spiral coils is established. In the model, the rectangle is used instead of the crack in the shell. The propagation of ultrasonic S-wave in the defects of 5mm*1mm and 10mm*1mm is studied, and the image is generated by MATLAB software. The results show that the EMAT shear wave can locate the position and image the size in the object defects.

Moisture is one of the main factors affecting the insulation performance of oil-paper insulated capacitive equipment. Accurately assessing the insulation condition of wet oil-paper capacitive equipment is the focus of preventive testing of electrical equipment. In this paper, the application of frequency domain dielectric spectroscopy based on dielectric response principle in moisture evaluation of oil-paper insulated capacitor bushing is studied. The testing principle of FDS and PDC and the time-frequency domain dielectric response conversion based on extended Debye model are explained. Through setting up test bushing testing platform and testing analysis of 500kV damp bushing, it is confirmed that the low-frequency dielectric loss value of the FDS test curve can be used as an effective criterion for the insulation of the oil-paper bushing insulation. The frequency domain dielectric response technology is used to evaluate the moisture content of the oil-paper capacitor type bushing. The research results are of great significance to ensure the safe operation of the case.

Steel fiber reinforced concrete (SFRC) has gained popularity in the last decades attributed to the improvement of brittleness and low tensile strength of concrete. This study investigates the effect of three shapes of steel fibers (straight, hooked end, and corrugated) with four contents (0.5%, 1%, 1.5%, and 2%) on the mechanical properties (compression, splitting tension, shear, and flexure) of concrete. Thirteen groups of concrete were prepared and investigated experimentally. Test results indicated that steel fiber had significant reinforcement on mechanical properties of concrete. When the steel fiber content increases from 0.5% to 2.0%, the compressive strengths increase about 4–24%, splitting tensile strengths increase about 33–122%, shear strengths increase about 31–79%, and flexural strengths increase about 25–111%. Corrugated steel fiber has the best reinforced effect on strength of SFRC, hooked end steel fiber takes the second place, and straight steel fiber is the least. Calculated formulas of compressive, splitting tensile, shear, and flexural strengths were established with consideration of the bonding properties between concrete and steel fiber. Influence factors of steel fiber αf and concrete matrix strength αc were put forward and determined by regression analysis of experimental data. Calculated results agree well with the experimental results.

The application of T-junction has already been extended from the petroleum engineering to the emerging advanced thermodynamic cycles. How a T-junction, as a separator in an emerging thermodynamic cycle, affects the cycle efficiency is discussed in this paper. Firstly, based on the Eulerian method, parametric studies on the local pressure drop coefficients are conducted and two new local pressure drop (LPD) coefficients are predicted in this paper. Then, the effects of pressure drop on a composition adjustable organic Rankine cycle efficiency is analyzed. In the process, a composition adjustable organic Rankine cycle with zeotropic mixtures R245fa/R123 is chosen to calculate the effects of pressure drop on thermodynamic cycle efficiency. The quality of the outlet of the evaporator is assumed as 0.7, and the composition ratio as 0.6/0.4. The results show that the pressure variation of T-junction affects the adjustable organic Rankine cycle efficiency, and reasonable phase separation ratio can improve the thermodynamic cycle efficiency. The pressure drop could cause composition diffusion. In addition, two new local pressure drop coefficients are obtained. And the results demonstrate that K12J declines slowly with the increases of density ratio (ρ2/ρ1) and decreases with the increases of mass fraction of taken off (F). K13J shows an obvious trend with diameter ratio (d3/d1) and F. This work could push the research of T-junction as a separator in the adjustable organic Rankine cycle.

The space holder technique is widely used to fabricate metal foams, especially titanium foam. However, how to obtain the desired porosities is a big challenge for this technique, because they are not always equal to the expected ones. The results of the previous study (i.e., P = ax + b, where a = 1/(1 + δ), b = δ/(1 + δ)) give a very interesting conclusion that is the change rate of pore volume (δ) is an indefinite mathematical constant. Based on the research work, we obtains a new result by establishing a mathematical model, which can be expressed as equation δ = ϕ − 1. Here, ϕ is the length index product of the ratio between the actual length and the designed length of the sintered metal foam. It reveals that the length index product (ϕ) is also an indefinite mathematical constant and we can measure its value. Therefore, solving δ means both a and b are solved, so the porosity (P) of titanium foam can be predicted by the equation P = ax + b, depending on the spacer content (x). This indicates that in the absence of porosity measurements, the macroscopic dimensions of the sintered metal foam can be measured to obtain a controlling equation for porosity.

The thermal properties and crystallization behavior of MgO BaO SiO2 B2O3 Al2O3 glass have been investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM). After crystallization at temperature (800 °C) close to the DSC crystallization peak, dendritic hexacelsian crystals are found to form as the major crystalline phase among glass. The crystallization kinetics was studied by analyzing DSC curves with Chen's and Ozawa's equations. The mean crystallization activation energy and Avrami's parameter are evaluated to be 229 kJ/mol and 1.4, indicating that the crystallization process occurs predominantly by surface crystallization as consistent with experimental data. Concurrent emissions of Eu2+ and Eu3+ under 304 nm excitation demonstrate that partial reduction of Eu3+ to Eu2+ occurs, which could be ascribed to the partition of Eu3+ into the precipitated hexacelsian crystals during the sintering process of glass ceramics. These results indicate that glass ceramic route may serve as an intriguing way for synthesis of phosphors applicable to lighting and display fields.

This paper presented a fundamental investigation on the formation mechanism and compatibility of microstructure/mechanical property of Fe-Cr-Ni-B steel samples, which were built by the divided-area forming and integral connection methods. Results indicate that the stress at the edge of the specimen produced in additive manufacturing is reduced by the divided-area forming and integral connection method. According to the microstructure analysis using stereology microscopy/optical microscopy/scanning electron microscope/X-ray diffractometer/Schaeffler diagram, the macrostructure is distributed in strip band geometry and the microstructures consist of dendrites with the intermetallic phases containing austenite phase, boride/matrix eutectic phase. Additionally, the macrostructure strips near the bonding line bend to the building direction and are discontinuous because of the unique forming method. However, the microstructures and composition of the samples are homogeneous. Due to the existence of boride and the finer microstructures, mechanical properties analysis shows that the alloy has high hardness, high ultimate strength and bad deformability. The hardness distribution is homogeneous apart from some positions of the re-melting zone and the heat-affected zone near the bonding line, which have a relatively lower hardness because of differences in microstructure.

A dual-resonance-coupling phenomenon and the sensing characteristics of an in-fiber modal interferometer based on cascaded long period gratings inscribed in an all-solid photonic bandgap fiber are demonstrated. Theoretical and experimental investigations reveal that the dual-resonance dips result from the coupling between fundamental core mode and two different kinds of LP01 cladding supermodes. Due to the deep grooves and asymmetric index distribution along the long period grating caused by side illumination, this dual-resonance interferometer is sensitive to polarization and twist, and the dual-resonance dips according to different LP01 cladding supermodes exhibit different responses to twist. Furthermore, the transmission loss and the resonance wavelength of each interference dip show discrimination in sensitivities of temperature and twist, making it a good candidate for multiple physics parameters measurements.

Understanding the anatomical variations in the human cochlea is important for cochlear implants. This study examined these variations using a reconstructed fusion model of the skull and temporal bone. The three-dimensional (3D) digital model of the temporal bone was reconstructed from multiple axial micro-computed tomography (CT) scans of temporal bone and high resolution CT of the skull from 15 cadavers. A skull model was reconstructed and merged with the reconstructed temporal bone. The 3D relationship between the cochlea and the skull's mid-sagittal plane was analyzed. The α and β angles of the cochlear autogenous rotation and bottom position, respectively, further subdivided the cochlear spatial orientation. The relationship between the base of the cochlea and the round window was evaluated with the Φ angle. Cochlear size was measured and the relationship was statistically analyzed. Cochlear implant electrode arrays were observed in five cases of right-temporal bone specimens. The α, β, and Φ angles were 46.01 ± 9.65, 56.79 ± 3.58, and 44.41 ± 7.23, respectively. The α angle varied greatly and was negatively correlated to the Φ angle (correlation coefficient = -0.211, P < 0.05). Among the five specimens, the α and Φ angle of the 2R and 4R cochlear specimens was lower and higher than the mean value, respectively. These measurements revealed variations in the size and position of the cochlea. Some of these variations may require surgical adjustments for insertion of electrodes with cochlear implants and present a greater challenge for implantation of cochlear electrode implantation. These data also provide a better understanding of variations in human cochlear anatomy. Anat Rec, 301:1086-1095, 2018. © 2017 Wiley Periodicals, Inc.

The combined effect of ultrasonic vibration (UT) and applied pressure (P) on the microstructure and mechanical properties of the as-cast Al-5.0Cu-0.6Mn-0.6Fe alloy was investigated by optical microscope (OM), scanning electron microscope (SEM) coupled with energy dispersive X-ray (EDX), image analysis as well as tensile test. The results show that the P+UT processing has an significant effect on the morphology and size of α-Al, Fe-rich intermetallics, and Al2Cu, which promotes the morphology of α-Al transformation from dendritic to globular structure and significantly reduces the size of α-Fe, Al6(FeMn), and Al2Cu phase. The P+UT processing is helpful to reduce the degree of bimodal structure which usually occurs during squeeze casting. It is also effective to reduce the segregation along the grain boundary. The best tensile properties of as-cast alloy produced by the P+UT are ultimate tensile strength (UTS) 268 MPa, yield strength (YS) 192 MPa, and elongation 17.1%, which are 64%, 59%, and 307% higher than those of the non-treated alloy, respectively.

The spherical silica particles in narrow size distribution with different diameters of 90 nm, 200 nm, 320 nm and 400 nm were prepared by the modified Stober method and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and dynamic light scattering (DLS). The phase composition of particles was characterized by X-ray diffraction. The results indicated that each of the silica particle samples was in amorphous state. The shear thickening fluids (STFs) comprising 53 vol.% of silica particles and 47 vol.% of polyethylene glycol with molecular weight of 200 g mol−1 (PEG200) were prepared and evaluated. The influence of size and size distribution on the critical shear rate and the intensity of shear thickening were analyzed. The STFs prepared by silica nanoparticles with a diameter of 90 nm showed the giant rheological effect with the critical shear rate of 2.51 s−1, the largest viscosity of 45,500 Pa∙s and the yield stress of 181 kPa. The experiments and the analysis results demonstrated that the suspensions prepared by nanoparticles have high intensity of shear thickening.

NaCl and its mixed salt have many advantages as a medium of solar energy phase change thermal storage at moderate and high temperature. But molten chloride has sharp corrosive action on metal thermal storage vessel. The corrosion behavior of three kinds of Ni-10 wt% Fe based alloy (1#, 2# and 3#) in 850 °C molten NaCl was studied. The content of Al in 1#, 2# and 3# sample was 0.0 wt%, 5.0 wt% and 10.0 wt%, respectively. The components of NaCl after corroding and corrosion products on samples surface were analyzed. Elements change trend and corrosion characteristics on cross section of the three samples were contrasted. Corrosion mechanisms were discussed finally. Results show that the kinetics curves of the three kinds of sample obey a liner rule. The average mass loss rate declines when Al is added in the sample. The rate of 2# and 3# is only 12% and 20% of that of 1#, respectively. There are two reasons for the value reduction: firstly, Al will be oxidized prior to oxidization of Fe or Ni, and the atomic mass of Al is small; secondly, Al2O3 is very stable at high temperature as corrosion products. However, when the content of Al is very high (for example 10 wt% in here) in Ni-10 wt% Fe based alloy, Al oxidized on sample surface provides a convenient condition for Al atom transmission from sample inside to surface. Al2O3 film becomes thick and exfoliates easily. The exfoliation increases the average mass loss rate in turn.

The four spectral tunable light sources based on prism + DMD, grating + DMD, prism based + nematic liquid crystal and multicolor LED based are summarized. The first three spectral tunable light sources work similarly, mainly by projecting a fixed continuous spectrum of light output from the light source into the dispersive element, and then projecting onto the spectral modulation device through the converging lens to form a series of flat on the spectral modulation device. Straight spectral band, through the computer controlled spectral modulation device to change the output to the latter spectral distribution, and finally through the uniform mixing system to produce a prism + DMD-based spectral tunable light source with higher output energy, due to the prism used by the dispersive element, Therefore, its spectral resolution is non-linear, and the spectral resolution is higher at a shorter wavelength, and the uniform temperature source with adjustable color temperature and adjustable brightness. The spectral resolution is lower at longer wavelengths. The spectrally tunable source based on prism + DMD has a spectral resolution that does not change with wavelength due to the grating used by its dispersive element. However, due to the multi-level diffraction of the grating, its energy utilization is low, only 35% of the prism. about. The spectral modulation device based on the prism + nematic liquid crystal uses a nematic liquid crystal. The size of the nematic liquid crystal is large, and there is almost no diffraction phenomenon in the infrared band, so the spectral resolution in the infrared band is high. . The spectrally tunable light source based on multi-color LED has the lowest cost. It is combined by a plurality of monochromatic LEDs with different center wavelengths and different bandwidths, and the brightness and darkness of each LED is controlled by a special control algorithm to emit a whole band. The spectrally adjustable light output, and finally, after the light is mixed by the uniform light mixing system, a uniform light source with adjustable color temperature and adjustable brightness can be formed at the exit.

With the increasing demand for high voltage level and miniaturization of extensive power equipment, ZnO ceramics, as key energy absorption elements in DC current breakers, are required to possess even higher voltage gradient. In this paper, nano-sized starting materials ZnO powders were employed to achieve the high voltage gradient. The effect of sintering temperature on the microstructural evolution and electrical characteristics of these obtained varistors were investigated by means of XRD, SEM, J-E measurement and dielectric spectroscopy. Experimental results showed that the fine sized powder could contribute to the high voltage gradient; the optimized sintering temperature for nano-sized starting ZnO powders was 1050°C. The obtained ZnO ceramics sintered at 1050°C exhibited high voltage gradient of 805 V/mm, which was over 4-times than that of the commercial varistors. Meanwhile such ceramics possessed large nonlinear coefficient of 30 and the low leakage current of 1.38 μA/cm2. Such improved performance may could be ascribed to the decreased grain size, the enhanced microstructure homogeneity and the well-formed double Schottky-barrier. Such result indicated the nano-sized ZnO powders as the starting raw material may benefit the high performance of ZnO varistors and is a promising solution to the miniaturization of DC current breakers.

In this paper, 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA), which is an organic phosphonic acids (OPA), is selected as the protic media to prepare phosphonated proton exchange membranes based on polyvinyl alcohol (PVA) by solution casting technique. The obtained PVA membranes were characterized using fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), and wide angle X-ray diffraction (WAXD). The proton conductivities and the methanol permeabilities through the membranes were investigated in terms of various OPA content. The proton conductivity of the PVA membrane measured at room temperature was close to that of the nafion-117 membrane measured under the same test conditions (1.02 × 10−3 S·cm−1). But in the low relative humidity (50%), the proton conductivity of the phosphonic proton exchange membrane has a conductivity of up to 8.17 × 10−5 S·cm−1, which was significantly higher than that of the sulfonate proton exchange membrane. The methanol permeabilities of the PVA membranes were in the range of 10−7 to 10−6 cm2/s in the room temperature, depending on the OPD content. The thermal stability of the composite membrane was enhanced with incorporating of PBTCA by presenting high initial decomposition temperature.

The heat storage performance of double - tank molten salt tank is better than a single - tank system. In order to obtain the heat storage mechanism of double pot molten salt, the spiral coil heat exchanger was placed in the annular gap composed of the cylindrical baffle and open end tank wall. The energy release characteristics of the double tank are analyzed in detail. The results show that the cylindrical baffle can adjust the molten salt flow field in the tank, the outlet temperature of heat exchanger, the heat transfer capacity and the transient heat transfer effect. The results of this study can be used as the basis of double tank design.

In the course of the ship’s navigation, a strong magnetic surface mount method is used to realize real-time observation of the temperature and salt elements of the sea surface. In order to ensure the stability of the magnetic module (the shield) during navigation, the force condition was analyzed with ANSYS Fluent, and a design calculation method was proposed. Firstly, numerical simulation analysis is carried out on the force of the shield. Secondly, the magnetic force of permanent magnets with different sizes is calculated. Through the analysis of the overall force, the size and total number of magnets required on the shield are finally determined.

Mammalian whiskers can perceive obstacles and airflows. In this study, an electronic whisker (E-whisker) sensor was designed and fabricated by setting a PVDF ring with symmetrical electrodes on the root of a fiber beam. Vibration displacements with different waveforms were applied at the free end of the E-whisker beam to study the relationship between the vibration displacements and the output signals. The E-whisker protrusion sensing ability was investigated by driving it to sweep through the surface of a base platform. A static E-whisker beam and a swinging E-whisker were then separately placed in a wind tunnel to detect the airflow perception of the sensor. The experimental results suggested that the E-whisker could sense the frequencies and amplitudes of displacements at its free end, the height and width of a platform or the heights of other irregular protrusions; the static E-whisker could sense the magnitude or direction of an impact airflow, while the swinging E-whisker could sense the magnitude of a constant airflow. Thus, this kind of E-whisker could perceive the environment and airflow through touch sensation and could be used as a physical model to study the principles and abilities of animal whiskers to perceive obstacles and airflows.

Ferroelectric random access memory (FeRAM) has been regarded as a promising technology for next-generation nonvolatile storage due to its excellent data storage performance and nonvolatile storage characteristics. However, fatigue degradation properties seriously impede the development and large-scale commercial use of FeRAM. In this paper, the interaction mechanism and enhancement of ferroelectric fatigue in lead zirconate titanate (PZT) thin film are investigated by the first-principles calculations (DFT). Theoretical calculations suggest that the coupling between oxygen vacancies and 180° domain walls in PZT is responsible for ferroelectric fatigue. Oxygen vacancies are more likely to be formed closer to domain wall, the “pinning” between oxygen vacancies and domain wall makes the migration of domain wall difficult, resulting in the suppression of polarization reversal and ultimately fatigue in ferroelectric thin film. The insertion of Ba(Mg1/3Nb2/3)O3 (BMN) can absorb the oxygen vacancies in PZT and reduce the concentration of oxygen vacancies, and in doing so, the ferroelectric fatigue problem caused by the “pinning” effect of the oxygen vacancies can be eliminated. Moreover, the PZT thin films are deposited on Pt/Ti/SiO2/Si(100) by the sol-gel method with using BMN buffer layer. The remnant polarization (Pr) of PZT film decreases by 51% and the PZT/BMN film remains 85% after 1010 cycles. Furthermore, it keeps stable even up to 1012 cycles. This paper demonstrates that the PZT/BMN film with excellent ferroelectric and fatigue endurance possesses the promising applications in FeRAM.

With the rapid development of information technology, a wavelength-tunable vertical cavity surface emitting laser (VCSEL) is urgently needed as an optical signal source in dense wavelength division multiplexing (DWDM). Liquid crystal tunable VCSEL realized by utilizing the birefringence characteristics of liquid crystal has the advantages of stable polarization, high reliability, continuous wavelength tuning. In this paper, a liquid crystal tunable VCSEL structure based on intracavity sub wavelength grating is designed, and the influence of liquid crystal layer and sub wavelength grating on the wavelength tuning characteristics of VCSEL are analyzed and studied in depth. The results show that the thickness of the liquid crystal layer in the tunable VCSEL structure not only affects the wavelength tuning range, but also determines the mode hopping in the tuning process. In addition, an effective refractive index antireflection layer is formed by designing the subwavelength grating structure, and the refractive index difference between the liquid crystal layer and the semiconductor layer is optimized to further improve the wavelength tuning range and tuning efficiency. When the center wavelength is 980 nm, the tuning range is increased by 42%, reaching 41 nm, and the wavelength tuning efficiency is increased by 41%. It provides a new method of designing the VCSEL laser with high beam quality and continuous wavelength tuning.

As a non-volatile memory, zero-dimensional quantum dot resistive random access memory (RRAM) has shown broad application prospects in the field of intelligent electronic devices due to its advantages of simple structure, low switching voltage, fast response speed, high storage density, and low power consumption. Tin dioxide quantum dots (SnO2 QDs) are a good option for resistive functional materials with excellent physical and chemical stabilities, high electron mobilities, and adjustable energy band structures. In this paper, the SnO2 QDs with sizes of 2.51 nm, 2.96 nm and 3.53 nm are prepared by the solvothermal method, and the quantum size effect is observed in a small size range and the effective regulation of resistive switching voltage is achieved based on its quantum size effect, which is the unique advantage of quantum dot material in comparison with that of bulk material. Research result shows that as the size of SnO2 QD increases, the SET/RESET voltage gradually decreases from –3.18 V/4.35 V to –2.02 V/3.08 V. The 3.53 nm SnO2 QDs have lower SET/RESET voltage (–2.02 V/3.08 V) and larger resistive switching ratio (> 104), and the resistive switching performance of the device has changed less than 5% after having experienced durability tests 2 × 104 times, showing good stability and retention. Besides, according to the fitting of charge transport mechanism, SnO2 QD RRAM exhibits Ohmic conduction under LRS, while Ohmic conduction, thermionic emission and space charge limit current work together during HRS. The resistive switching effect of SnO2 QDs is controlled by trap filled limit current and interface Schottky Barrier modulation; the trapping/de-trapping behavior of internal defect potential well of SnO2 QDs on electrons dominates the HRS/LRS switching, while the effective control of ITO/SnO2 QDs and SnO2 QDs/Au interface Schottky barrier is the key to accurately regulating the switching voltage. The reason why SnO2 QD RRAM exhibits good size-switching voltage dependence is that the larger SnO2 QD has lower Fermi level and interface Schottky barrier height, so the junction resistance voltage division is reduced, and the SET/RESET voltage decrease accordingly. This work reveals the huge application potential and commercial application value of SnO2 QDs in the field of resistive switching memory, and provides a new option for the development of RRAM.

A high power 755 nm continuous-wave (CW) laser with high beam quality based on the Alexandrite crystal was demonstrated. The Alexandrite lasers single-end-pumped by 638 nm laser diodes (LDs) and 532 nm solid-state laser were studied comparatively, then the CW output power, optical-to-optical conversion efficiency, and slope efficiency pumped by 638 nm LDs were 3.9 W, 19.7%, and 23.7%, respectively, while they were 2.1 W, 10.0%, and 12.9%, at nearly the same conditions except that it was pumped by 532 nm solid-state laser. The results show that the Alexandrite laser pumped with 638 nm LDs can obtain higher CW output power and higher conversion efficiency. Moreover, a CW output power of 6.2 W at 755 nm of Alexandrite laser double-end-pumped by a 638 nm LDs was achieved with the optical-to-optical conversion efficiency and the slope efficiency of 16.3% and 24.2%, respectively. The beam quality factor M2 was better than 1.47 at the CW output power of 5.0 W, which was the highest CW output power of Alexandrite laser with the diffraction limit to the best. This high power and high beam quality 755 nm Alexandrite laser provides the fundamental frequency source for the development of CW ultraviolet lasers.

A series of polyborosiloxanes (PBSs) was synthesized by mixing hydroxy-terminated polydimethylsiloxanes (PDMS) and boric acid (BA) in toluene at 120 °C. The molecular masses of selected PDMS precursors were in a wide range, covering from below up to far above the critical entanglement molecular mass of PDMS. The reaction kinetics was followed by using Fourier transform infrared (FTIR) spectroscopy. Unreacted BA was removed from raw PBSs after the reactions. The influence of molecular mass of PDMS precursors on the rheological property of PBSs was explored by dynamic oscillatory frequency sweeps. The results showed that the plateau elastic moduli of PBSs were highly dependent on the molecular mass of PDMS precursors. The plateau elastic moduli of PBSs decreased at first and then increased with increasing molecular mass of PDMS precursors. PBS1 and PBS2 prepared from unentangled PDMS precursors showed sufficient fits by using the two-mode Maxwell model, whereas PBS3 to PBS6 prepared from highly entangled PD...

The effects of integrating micro-Al 2 O 3 onto carbon fiber surface and its contents on mechanical properties of carbon fiber reinforced polymer composites were investigated. Mode II interlaminar fracture toughness, impact strength, flexural properties and initial modulus were determined by mechanical test machines and dynamic mechanical analyzer. The reason for performance improvement was discussed based on scanning electron microscopy. The mode II interlaminar fracture toughness, impact strength, and flexural strength of composites without addition of micro-Al 2 O 3 were 348 J/m 2 , 118 kJ/m 2 and 682 MPa, respectively. However, the mechanical properties of modified composites were improved significantly. The mechanical properties were optimum when the areal density of micro-Al 2 O 3 particles reached 15 g/m 2 at which the mode II interlaminar fracture toughness, impact strength, and flexural strength reached 522 J/m 2 , 161.7 kJ/m 2 and 759 MPa, respectively. Furthermore, these composites with addition micro- Al 2 O 3 in the layers showed an improvement in thermal property.