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The construction of multi-component composites has become an attractive strategy for high-performance microwave absorption through balancing the magnetic and dielectric loss. However, the influences of different components on absorption performance are ambiguous, which has inevitably hampered the widespread applications of microwave absorbents. Herein, we rationally designed the multi-component absorbers of N-doped carbon composited with Fe/Fe3C nanoparticles, and systematically investigate the impacts of Fe/Fe3C nanoparticles and Fe-Nx moieties on the microwave-absorbing capacities. It is found that the coexisitence of Fe/Fe3C and Fe-Nx is indispensable to realize the strong microwave absorption ability by simultaneously enhancing the dielectric and magnetic loss in the frequency range of 2-18 GHz. As expected, our optimal absorber dispersed in paraffin with a filler loading of 15 wt% exhibits the minimum reflection loss (RLmin) value of -49 dB and the maximum effective absorption bandwidth (BWeff) value of 4.2 GHz at a low thickness. Our work specifies the importance and influence of the coexistence between the Fe-Nx configurations and Fe/Fe3C nanoparticles in the carbon-based composites for the superior microwave absorption and inspires the future fabrication of extraordinary materials in the electromagnetic field.

The extremely cold weather may cause cascading failures of power grid components, resulting in large-scale outages and economic losses. Thus, to make better anti-disaster preparations, it is necessary to assess the system-level risk of the power grid efficiently with extreme weather predictions. This paper proposes a risk assessment method for power grids based on the probabilistic graphical model (PGM). First, the time-varying failure probabilities of power lines are estimated with consideration of the cascading effects of the direct impact of disasters and power flow transfer. Then, load supply reliabilities are fast inferred by solving the probability graph model of power component failure propagations. Finally, the overall outage risk is evaluated by considering the capacity and importance of different loads, which helps to improve anti-disaster decisions. Through theoretical analysis and case studies, the efficacy of the proposed method is verified.

GH5188 high-temperature alloy specimens were fabricated by selective laser melting (SLM) and influencing laws of laser power, laser velocity and laser energy density on density of specimens were researched. The results shows that along with the laser energy density increases from 73.02 J/mm3 to 88.18 J/mm3, porosity in specimens decrease and relative density increases from 98.86% to 99.75%. However, as the laser energy density increase further, the density begins to decrease continuously. The main causes that effects relatively density including: the powder is not fused at low energy density, as well as the powder splash and gasification at higher energy density. Neither inadequate nor excessive laser energy density is conducive to improvement of density of specimens. As the increase of laser velocity and laser power, density of specimens increases firstly and then decreases. The variation trend of relative density is similar with that of laser energy density and there are reasonable ranges of laser velocity and laser power. However, influencing laws of laser velocity and laser power on density of specimens are different.

The isomerization process of donor-acceptor Stenhouse adducts (DASAs) is closely related to its surrounded physicochemical environment, this work focuses on the promotion of ester-modified glass fiber to the isomerization process of DASAs compared with the untreated glass fiber. The ester-modified glass fiber is prepared through a two-stage method, the coating procedure is stepwise monitored through the scanning electron microscope(SEM) and the energy dispersive spectrometer(EDS). The ester functional groups on the outmost layer of glass fiber act as a catalyst, lowering the energy level of the intermediate state of DASAs and therefore promoting isomerization performance of DASAs where the time to reach cyclic dominant states shorten from 116 s to 82 s and the efficiency of cyclic-to-linear increased almost 6 folds.

A shaping test of CuSn10 powders was carried out by using the selective laser melting (SLM) technology to study influences of process parameters of SLM on compactness of specimens. Meanwhile, process parameters were optimized based on the response surface methodology. Meanwhile, phase composition and microstructure of formed part were analyzed by XRD and OM. Results demonstrated that as the energy density of laser body increases from 146.7 J·mm-3 to 181.3 J·mm-3, pores of samples decrease and the compactness increases from 98.97% to about 99.7%. Subsequently, the compactness begins to decrease with the continuous increase of laser energy density. The incomplete melting of powder under low energy density and gasification of powders under high energy density are major factors that influence the compactness. Over low or high laser energy density is disadvantageous for the improvement of compactness. A mathematical model of interaction between three factors (laser power, laser scanning speed and scanning space) and response value (compactness) was built up by using the BBD principle design test of response surface methodology. The degree of fitting (R2) and correction coefficient (R2 adj) of the model were 0.9952 and 0.9866, which agree well with the fitting degree of experimental tests. Among three factors, influences of laser power and scanning speed on compactness are equivalent and more significant than scanning space. The optimal process parameters which were predicted by the model were laser power=331.471 W, scanning speed=648.045 mm·s-1, scanning space=69.9302 μm. Under this circumstance, the compactness of CuSn10 powders after SLM is 99.75%. According to experimental verification, the practical value of compactness is 99.74%, showing a very small relative error. This proves that the BBD model is reliable. The shaped part is mainly composed of α-Cu phase and metastable phase β’-Cu13.7Sn. Compared with the original powders, the content of metastable phase β’ increases significantly, while the δ-Cu41Sn11 phase disappears.

To verify validity of new method for preparing dissimilar metals with high melting point through double laser assisted friction stir welding (FSW), butt welding tests on dissimilar metals of TC4 and GH4169 were carried out by conventional FSW, single laser assisted FSW and double laser assisted FSW, respectively. Macroscopic morphology, microstructure and mechanical properties of butt-joint were analyzed. Results demonstrated that the conventional FSW surface is relatively rough, manifested by existence of many trims and rags, incomplete mixing of joint and dissimilar materials, as well as a certain proportion of pore defects. The single laser assisted FSW surface is even and smooth, manifested with few trims and rags. Compared with conventional FSW, the dissimilar material mixing is improved significantly, and there are few pores. The double laser assisted FSW surface shows the best quality, manifested by the fewest trims and rags. The mixing of dissimilar materials is further improved and the joint has good shaping, without obvious defects. Tensile strengths of joints of conventional FSW, single laser assisted FSW and double laser assisted FSW were 238 MPa, 423 MPa and 505 MPa, respectively. Laser assisted FSW has the higher tensile strength, which is attributed to the more complete material mixing and thicker layer of element diffusion. The laser preheating can decrease axial downward pressure of stirring head and radial stress of the stirring needle in the welding process significantly compared with those in conventional frictional stir welding. In particular, double laser preheating can make stresses on the stirring needle more uniform. This is conducive to mutual flowing and integration of dissimilar materials for FSW. Meanwhile, it can reduce the wearing loss between the stirring head and welding component. Double laser preheating can prolong service life of stirring heat significantly and it can improve welding speed significantly under the same rotating speed of the same stirring heat, thus enabling to increase welding efficiency.

NiCrBSi coating reinforced with WC was prepared on the steel substrate surface of 42CrMo alloy structure based on coaxial powder-feeding laser cladding technology by using the YLS-6000 fiber laser. Phase composition, microstructure, microhardness and wear resistance of specimens were discussed by the X-ray diffractometer (XRD), scanning electron microscope (SEM), microhardness meter and ring-block friction wear testing machine. Results demonstrated that the composite coating is mainly composed of γ-Ni solid solution and WC, accompanied with phases like FeNi3, B2Co3, CoCx, FeCr0.29Ni0.16C0.06, W3C and Co3W3C6. The top, middle and bottom of the cladding layer are occupied by tiny dendrites, coarse columnar dendrites and cellular crystals perpendicular to the interface. Moreover, good metallurgical bonding is formed between the coating and base. Hardness and wear resistance of the composite coating are far higher than those of the 42CrMo base. According to west test, the base presents typical adhesive wearing characteristics, while the composite coating mainly shows abrasive wearing performances.

With characteristics of high cladding efficiency, small grain size and low porosity, follow-up feeding pulse current assisted laser cladding can realize online self-healing of cracks on the cladding layer and get a crack-free cladding layer. It is a very promising new laser cladding technology. In this study, effects of cladding parameters (laser power, scanning speed, powder feed rate, pulse current, pulse frequency and pulse width) on dilution rate of coating were discussed through a six-factor three-level orthogonal experimental design method. Results demonstrated that laser power, scanning speed and powder feed rate can influence dilution ratio greatly, while pulse current, pulse frequency and pulse width influence the dilution ratio slightly. Among the top three major factors, laser power can influence the dilution ratio mostly, followed by powder feed rate and scanning speed. The dilution ratio increases with the increase of laser power, scanning speed and pulse width, but it decreases with the increase of powder feed rate and pulse frequency. With the increase of pulse current, the dilution ratio decreases firstly and then increases.

Nanostructured Al2O3-13wt.%TiO2 ceramic coatings were prepared on the TiAl alloy surface by using the plasma spraying and plasma spraying-laser remelting composite technology, respectively. Hot corrosion behaviors of these two coatings in 75%Na2SO4+25%NaCl (mass fraction) fused salts under 850 °C were discussed. Moreover, phases and microstructures of specimens after the corrosion were analyzed by X-ray diffractometer (XRD) and scanning electro microscope (SEM). Effects of laser remelting on hot corrosion resistance of coatings were explored. Results demonstrated that hot corrosion of ceramic coating prepared by plasma spraying is serious, but the hot corrosion resistance can be improved effectively after laser remelting. Laser remelting specimens show the higher hot corrosion resistance for two reasons. On the one hand, laser remelting forms a uniform and dense remelting layer by eliminating the lamellar structures and most pores of the coating layer, thus decreasing the corrosion diffusion channels during hot corrosion. On the other hand, laser remelting changes the metastable-phase γ-Al2O3 into stable-phaseα-Al2O3.

To explore effects of temperature field in laser cladding on structure of ceramic coating prepared by plasma spraying, a finite element model of continuous moving three-dimensional temperature field of laser cladded Al2O3-13wt.%TiO2 coating prepared by plasma spraying was constructed by the parametric design language of ANSYS finite element software to analyze temperature field during laser cladding. According to analysis results, it is very difficult to realize complete remelting of the whole preset ceramic coating during laser cladding when it is thick, which is related with the relatively low thermal conductivity of the ceramic materials. The whole coating can be divided into remelting zone, sintering zone and residual plasma spraying zone according to temperature field distribution in the zone of cladding. Given the optimal technological parameters, relatively thick remelting zone and sintering zone could be gained under the relatively low laser cladding power and relatively low scanning speed. Experimental results demonstrated that the ceramic coating after cladding formed remelting zone with small-sized and dense isometric crystals, sintering zone and lamellar residual plasma spraying zone. Moreover, the calculated results of thickness of the remelting zone and sintering zone conformed well to experimental values. This proved that the constructed finite element model is accurate and reliable.

We report on a nanosecond all-fiber amplifier with repetition rate of tens of MHz. It is based on a passively mode-locked fiber oscillator at 1064 nm, which has a pulse width of 28 ps and repetition rate of 27.7 MHz. The single-mode fiber with length of 8 km is adopted as a fiber stretcher, in which new frequency components are introduced by strong nonlinear effect such as self-phase modulation, resulting in the broadening of spectral bandwidth from 0.4 nm to around 20 nm. The group-velocity dispersion of the 8 km fiber stretcher is −38 ps (nm km) −1, which stretches the pulse duration of the picosecond pulse to 1–7 ns. At the repetition rate of 27.7 MHz, an average power of 54 W is demonstrated with pulse width of 1.3 ns, and 21 W is achieved with pulse width of ∼5 ns, which have optical-to-optical conversion efficiencies of 41.2% and 30.1% respectively. This all-fiber amplifier based on the passively mode-locked fiber oscillator and 8 km single-mode fiber stretcher is capable of delivering nanosecond pulses while maintaining an ultra-high repetition rate of tens of MHz.

Conventional and nanostructured ZrO2-7wt.%Y2O3 thermal barrier coatings (TBCs) were prepared by plasma spraying technology. Microstructure and hot corrosion resistance of two TBCs in 75%Na2SO4+25%NaCl (mass fraction) mixed molten salt under 850 °C were compared. Meanwhile, hot corrosion failure mechanisms of TBCs were investigated. Results demonstrated that both conventional and nanostructured TBCs were typical lamellar stacking characteristic. However, compared with conventional TBC, the nanostructured TBC presented the base phase which is gained from recrystalization of fully melted nano-particles as well as the embedding phase of partially melted nano-particles. The nanostructured TBC has lower porosity and higher density. For both conventional and nanostructured TBCs, hot corrosion failure is caused by partial transformation of tetragonal phase (t-ZrO2) into monoclinic-phase (m-ZrO2) martensite as a response to the consumption of the stabilizer Y2O3. However, the nanostructured TBC generally has lower degree of hot corrosion and better protection to the metal bonding layer and matrix compared with conventional TBC.

We demonstrate an all-fiberized narrow-linewidth nanosecond amplifier with high peak power, tunable pulse width, and repetition rate. A fiber-coupled narrow-linewidth laser diode operating at 1064.1 nm is employed as the seed source, which is gain-switched to generate nanosecond pulses with tunable pulse widths of 1–200 ns and tunable repetition rates of 10 Hz–100 kHz. By utilizing a very-large-mode-area Yb-doped fiber with a core diameter of 50 μm in the power amplifier, thresholds of the stimulated Brillouin scattering at different pulse widths and repetition rates are increased. The maximum average power reaches 30.8 W at the pulse width of 4 ns and a repetition rate of 100 kHz, corresponding to an optical-to-optical conversion efficiency of ∼55.2%. Pulse energy and peak power are calculated to be 0.2 mJ and 50 kW, respectively, which are limited by stimulated Brillouin scattering. The 3-dB spectral linewidth remains around 0.05 nm during the power scaling process. The stimulated Brillouin scattering limited output powers at different pulse widths and repetition rates are investigated. Peak power of 47.5 kW (0.19 mJ) is obtained for the 4 ns pulses at a repetition rate of 50 kHz, which is nearly the same as that of 4 ns pulses at 100 kHz. When the pulse width of the seed source is increased to 8 ns, peak powers/pulse energies are decreased to 19.6 kW/0.11 mJ and 13.3 kW/0.08 mJ at repetition rates of 50 kHz and 100 kHz, respectively.

Molds are the basis of manufacturing of other products, and thus have higher requirements and more complex design processes than other products. Therefore, studying the technologies used in mold production is necessary. This paper aims to build a cloud manufacturing system of mold manufacturing enterprises based on the Java-based agent framework for multi-agent systems (JAFMAS). Specifically, according to the operation characteristics of different cloud-based manufacturing enterprises, this paper first made in-depth analysis of the cloud manufacturing and multi-agent technology, and put forward a hierarchical model of cloud manufacturing system based on multiple agents. Then, as per the structure of the agents and JAFMAS, the interaction and collaboration mechanism between agents in the system were analyzed to establish the functions of the cloud-based mold manufacturing system, thereby building a cloud-based manufacturing system for mold manufacturers based on JAFMAS.

We propose a fiber-solid hybrid system which consists of a semiconductor saturable absorber mirror (SESAM) mode-locked fiber seed with a pulse width of 10.2 ps and a repetition rate of 18.9 MHz, a two-level fiber pre-amplifier and a double-passing end-pumped Nd:YVO4 amplifier. In the solid-state amplifier, to enhance the gain and the extraction efficiency, a specially designed structure in which the seed light passes through the gain medium four times and makes full use of population inversion is used as the double-passing amplifier. Besides, the beam filling factor (the ratio of the seed light diameter to the pump light diameter) and the thermal lens effect of the double-passing amplifier are considered and its optical-to-optical conversion efficiency is further improved. To preserve the beam quality of the double-passing amplifier, a new method of spherical-aberration self-compensation based on the principles of geometrical optics is used and discussed. Our system achieves a maximum average power of 9.5 W at the pump power of 28 W, corresponding to an optical-to-optical efficiency of 27%. And the beam quality factor M 2 reaches 1.3 at the maximum output power.

With the continuous evolution of information technology, China has entered the information age, the use and promotion of smart phone is the inevitable trend of information evolution, but also an important sign of the information era. With large quantities of uses of smart phones, a large number of mobile apps have appeared, and different APP types have emerged. Currently, mobile apps have been applied in various fields, and gradually promoted to the field of sports education(SE), and various sports apps have emerged. The purpose of this paper is to chase down the problems existing in the use of sports APP in college SE by studying the use of smart phone sports APP in college SE under the background of informatization, so as to achieve the deep fusion of sports APP and college SE, and continuously promote the quality of SE. Firstly, this paper gives an overview of sports APP and college SE, and carries out use experiments of sports APP on the basis of information intelligence algorithm, analyzes the use situation of sports APP in college SE, and puts forward relevant use strategies on this basis. The experimental results show that the use of sports APP in college SE promotes teaching efficiency, but there are some problems at the same time, which must be paid enough attention.

Conventional and nanostructured ceramic coatings were prepared with conventional and nanostructured aggregate Al2O3-13wt.%TiO2 ceramic powders through plasma spraying and plasma spraying-laser remelting combined technique. Influences of feedstocks and laser remelting on erosion resistance of the prepared coatings were discussed, and the erosion failure mechanisms of four types of coatings were discussed. Results demonstrate that compared with coatings prepared by plasma spraying, the coating prepared by laser remelting has better erosion resistance. Given the equal conditions, nanostructured coating shows stronger erosion resistance than conventional coating. Conventional ceramic coating shows typical brittle erosion characteristics and nanostructured ceramic coating also shows brittle erosion characteristics, accompanied with certain degree of plastic erosion characteristics. Erosive wearing of plasma coating is mainly lamellar peeling, accompanied with certain degree of brittle ceramic particle crushing. Coating prepared by laser remelting present crack initiation and propagation on near surface, finally leading to crystal crushing and peeling of remelting layers.

A chromized layer was prepared on the alloy surface of TiAl intermetallics through using double-glow plasma alloying. The surface morphology, microstructure, and phase composition of the chromized layer before and after oxidation were observed by scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction. The cyclic oxidation behavior of the chromized layer at 850 °C was analyzed. Results demonstrated that the chromized layer had uniform and dense tissues and formed gradient metallurgical bonding with the substrate. The chromized layer further showed strong resistance to high-temperature oxidation in early-stage oxidation. However, the mixed oxides Cr2O3, Al2O3, and TiO2 were produced on the oxidation film–chromized layer interface during the long-term oxidation process. Given the poor adhesive strength of mixed oxides, the oxidation film underwent local peeling, which was attributed to the high Cr content of the chromized layer. However, the oxidation film in the peeled-off region healed automatically. Therefore, the chromized layer presented strong long-term resistance to high-temperature oxidation.

A new family of transparent, biocompatible, self-adhesive, and self-healing elastomer has been developed by a convenient and efficient one-pot reaction between poly(acrylic acid) (PAA) and hydroxyl-terminated polydimethylsiloxane (PDMS-OH). The condensation reaction between PAA and PDMS-OH has been confirmed by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectra. The prepared PAA-PDMS elastomers possess robust mechanical strength and strong adhesiveness to human skin, and they have fast self-healing ability at room temperature (in ~10 s with the efficiency of 98%). Specifically, strain sensors were fabricated by assembling PAA-PDMS as packaging layers and polyetherimide-reduced graphene oxide (PEI-rGO) as strain-sensing layers. The PAA-PDMS/PEI-rGO sensors are stably and reliably responsive to slight physical deformations, and they can be attached onto skin directly to monitor the body’s motions. Meanwhile, strain sensors can self-heal quickly and completely, and they can be reused for the motion detecting after shallowly scratching the surface. This work provides new opportunities to manufacture high performance self-adhesive and self-healing materials.

Al2O3-13wt.%TiO2 composite ceramic coatings were prepared by plasma spraying and laser remelting. Morphology, microstructure and phase composition were analyzed by scanning electron microscope (SEM) and X-ray diffractometer (XRD). Meanwhile, effects of laser remelting on thermal shock resistance of plasma-sprayed coatings were investigated and the thermal shock failure mechanism of coatings were discussed. Results demonstrate that after laser remelting, particles on the ceramic coating are refined and the lamellar structure disappears, thus increasing density and getting a remelting coating basically without defects like cracks. Laser remelting metastable phase γ-Al2O3 is transformed into a stable phase α-Al2O3. Due to low heat conductivity coefficient of ceramic materials, it is impossible to remelt the whole ceramic coating at laser remelting. An isometric crystal remelted zone with small grains, a sintered zone and a lamellar remained plasma-sprayed zone are formed on the remelting ceramic coating. Compared with plasma-sprayed coating, the laser-remelted coating has better thermal shock resistance. The thermal shock failure form of ceramic coating deposited by plasma spraying is basically corner peeling, while the thermal shock failure forms of laser-remelted ceramic coating includes both corner peeling and considerable local peelings in the center. Influences of laser remelting on thermal shock resistance of coating are mainly manifested as reduced initial failure resistance of coatings, decelerated crack propagation on coatings and changing failure mode of coatings.

Aiming at the operation safety for transmission lines in east Inner Mongolia seriously threatened by bird-caused damage in transmission and transformation equipment, according to the analysis of the law of bird activities in east Inner Mongolia, it is found that 463 species of birds are exist in east Inner Mongolia, and the bird damages are mainly caused by larger birds. Through the application effect of existing anti-bird measures, it is found that the current bird-repelling anti-bird measures can reduce the number of bird damages. However, the actual application effect of the anti-bird measures is still limited based on the operational data. Therefore, the guided improvement measures based on the artificial bird guide are proposed, and the corresponding models are made. The comparison with several existing bird-prevention measures is carried out and the test show that the combination of bird thorn of anti-bird measures prevention and the bird guides have a better effect. It is expected that the research can provide reference for the bird disease prevention and control work for east Inner Mongolia Power Grid.

The control of the impurity level in magnetically confined plasmas is a critical issue for future fusion devices. All the graphite tiles have been replaced by molybdenum tiles as limiter materials in the 2011 spring campaign in order to further reduce the recycling and hydrogen content of the plasma. A lithium coating technique has been applied as an important wall conditioning method to the HT-7 tokamak. The effective ion charge Zeff and impurity behavior with full metallic first walls of high-Z materials and lower hydrogen recycling have been investigated in a series of lithium coating experiments in this paper. Plasma performance and impurity behavior without wall coatings are studied in the early stage of the campaign. Comparison of Zeff with different plasma-facing components has been made. A typical lithium coating experiment has been analyzed in order to understand the effect of lithium coating. The evolution of main impurity line radiation, Zeff and the H/(H + D) ratio is analyzed in detail as lithium coating is repeated, indicating that lithium coating is a very effective tool to control impurity level and reduce hydrogen recycling. Furthermore, a boronization is conducted at the end of this campaign in order to make comparison with lithium coating. Experimental results show that lithium coating has much more advantages in edge recycling control, though it does not reduce impurity level as effectively as boronization.

Walk-off compensation using wedged cut type-II LBO was investigated theoretically and experimentally. An algorithm is proposed to find the optimized wedged cut angle to compensate the walk-off effect completely. Using a pulsed Nd:Y V O4 MOPA laser as the fundamental frequency infrared (IR) source, 36.3 W 355 nm frequency converted ultraviolet (UV) light was obtained using an optimized wedged cut type-II LBO for walk-off compensated third-harmonic generation (THG), giving a conversion efficiency of 37.1% from IR to UV. A comparative experiment using a conventional cut type-II LBO was also implemented. The results indicate that optimized wedged cutting of type-II LBO is an effective approach for walk-off compensation in efficient THG. The output performance of angle and temperature tuning for wedged cut type-II LBO was also investigated.

Near-ultraviolet (UV) InGaN/AlGaN light-emitting diodes (LEDs) are grown by low-pressure metal-organic chemical vapor deposition. The scanning electronic microscope image shows that the p-GaN micro-rods are formed above the interface of p-AlGaN/p-GaN due to the rapid growth rate of p-GaN in the vertical direction. The p-GaN micro-rods greatly increase the escape probability of photons inside the LED structure. Electroluminescence intensities of the 372 nm UV LED lamps with p-GaN micro rods are 88% higher than those of the flat surface LED samples.