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In recent years, the pursuit of high-efficiency electrochemical storage technology, the multivalent metal-ion batteries (MIBs) based on aqueous electrolytes have been widely explored by researchers because of their safety, environmental friendliness, abundant reserves and low price, and especially the merits in energy and power densities. This review firstly expounds on the problems existing in the electrode materials of aqueous multivalent MIBs (Zn2+, Mg2+, Al3+, Ca2+), from the classical inorganic materials to the emerging organic compounds, and then summarizes the design strategies in bulk and interface structure of electrodes with favorable kinetics and stable cycling performance, especially laying the emphasis on the charge storage mechanism of cathode materials and dendrite-free Zinc anode from the aspect of electrolyte optimization strategies, which can be extended to other aqueous multivalent MIBs. Ultimately, the possible development directions of the aqueous multivalent MIBs in the future are provided, anticipating to provide a meaningful guideline for researchers in this area.

Modulation of A-site defects is crucial to the redox reactions on ABO3 perovskites for both clean air application and electrochemical energy storage. Herein we report a scalable one-pot strategy for in situ regulation of La vacancies (V La) in LaMnO3.15 by simply introducing urea in the traditional citrate process, and further reveal the fundamental relationship between V La creation and surface lattice oxygen (Olatt ) activation. The underlying mechanism is shortened Mn-O bonds, decreased orbital ordering, promoted MnO6 bending vibration and weakened Jahn-Teller distortion, ultimately realizing enhanced Mn-3d and O-2p orbital hybridization. The LaMnO3.15 with optimized V La exhibits order of magnitude increase in toluene oxidation and ~0.05 V versus RHE (reversible hydrogen electrode) increase of half-wave potential in oxygen reduction reaction (ORR). The reported simple but effective strategy for in situ modulation of La-site defects and the corresponding influence on the electronic structure of MnO6 can benefit the development of novel defect-meditated perovskites in both heterocatalysis and electrocatalysis.

Magnetorheological fluid (MRF) is an intelligent material, which can be controlled by an external magnetic field. It is widely used in damping, finishing, mechanical transmission, sealing, and other engineering fields due to its magnetorheological (MR) effect. However, despite decades of research and experimental development, the wide application of MRF is still restricted by its serious settlement problem owing to the density difference between the magnetic particles and carrier liquid. Here, using the coprecipitation method, a kind of Fe3O4-modified nanolignocellulose (Fe3O4/NLC) composite fiber was characterized by its unique advantages such as low density, soft magnetism property, and high specific surface. These Fe3O4/NLCs were used as a kind of reinforcing particle with carbonyl iron powder in the new bidisperse MRF system. The performances of MRF samples were enhanced by these superior properties. We found that all MRF samples with composite fibers exhibited excellent antisettlement and dynamic mechanical characteristics and cooperativity between Fe3O4 and NLCs. Furthermore, redispersibility of MRF is qualitatively evaluated by a shearing test in this paper, explaining the high property of antihardening. This composite fiber improves the comprehensive performance of MRF and has the potential to be repeatedly used in engineering applications.

This paper describes film cooling characteristics of the novel combined configuration employing interrupted slot and trench holes on a vane endwall. Interrupted slot, formed by uneven thermal expansion between combustor and high-pressure turbine vane, can improve adiabatic film cooling effectiveness of the leading edge and pressure side-endwall junction by inhibiting the development of horseshoes vortex. Holes embedded into a straight trench were introduced to improve film efficiency comparing to cylindrical holes on vane passage endwall. The influences of lateral pressure gradient, slot coolant and step on crossflow of the hole coolant in trench were mainly discussed. Three dimensional Reynolds-averaged Navier-Stokes equations with shear stress turbulence model (SST k-ω) were used to obtain the flowfields and adiabatic film cooling effectiveness of a cascade model. Four hole blowing ratios M=0.5, 1.0, 1.5, 2.0 and two axial positions X/Cax= −0.05, 0 were considered. The coolant crossflow in trench on flat endwall of cascade passage trends to flow towards suction side due to the lateral pressure gradient rather than both sides on flat plate. For combined configuration of interrupted slot and trench holes, the step vortex rolls up hole coolant upstream of trench which changes η distributions comparing to that on flat passage endwall. Comparing to the cylindrical holes, better film cooling performance can still be obtained when arranging trench holes under high blowing ratios. The influence of hole’s axial positions was also discussed.

The aerothermal performance of interrupted slot and film holes was numerically investigated. Previous study indicates that the interrupted slot performs better compared to the conventional slot. In the meanwhile, the step formed along with the interrupted slot affects the film cooling characteristics. In this article, a row of film holes is arranged downstream of the step, and the mass flow rate for the interrupted slot is constant at 1%. Blowing ratio (BR) from 0.5 to 1.5 and density ratio from 1 to 2 were studied for the film holes. Endwall film cooling effectiveness distribution indicates that film cooling is easily affected by the secondary flow inside passage and the upstream step. Coolant traces are split into two parts due to the effects of step vortex and transverse flow. For different density ratios, increasing BR shows a different trend of film cooling effectiveness due to the variation of coolant momentum. The coolant jet is easily affected by the secondary flow when its momentum is low, but tends to liftoff when its momentum is too high. As a result, it is better to position the film holes far away from the upstream step. The total pressure loss coefficient distribution at the passage exit indicates that the coolant injection increases the total pressure loss. But density ratio has smaller effect on the loss variation. Besides, two axial positions of cooling holes were studied to improve the endwall cooling performance. Without the effect of step vortex, the film effectiveness of cooling holes is improved.

The existence of cracks in key components of engineering equipment is a huge threat to the safe operation of the equipment. The influence of four factors (length, location, orientation, and width of the crack) on the attenuation characteristic of signal propagation is studied through simulation and experiment. The orthogonal experimental design is applied to design the simulation scheme, and the signal affected by the four factors is simulated by the finite-difference time-domain method. The degree of influence of the different factors is evaluated by conducting an analysis of range and an analysis of variance. The results show that the influence of crack length and location on signal relative attenuation is more remarkable according to the significance level α = 0.05, followed by crack orientation and crack width. The attenuation trend in the experimental results is similar to the simulation. Therefore, the longer the crack length is, the easier it is to be detected by the acoustic wave technique, while the effect of crack orientation and crack width on identifying cracks is limited. The study successfully establishes the relationship between signal parameters and crack factors and offers a theoretical foundation for evaluating the status of cracks in key components.

Lutetium–yttrium oxyorthosilicate doped with cerium (LYSO:Ce) is a widely used scintillator, and the study of its nonlinear behavior under high excitation density is very significant owing to its direct influence on radiation measurements. Using a 266 nm ultraviolet laser to excite an LYSO:Ce crystal, the relationship between the photoluminescence (PL) light yield and excitation density was studied by Z scan experiments. The excitation threshold of the LYSO:Ce was obtained, which is about 2.3 J cm−3. Picosecond transient absorption of LYSO:Ce at 800 nm was obtained and used to analyze the dynamic process of carriers. The physical mechanism behind the nonlinearity was discussed and analyzed using the Forster dipole–dipole interaction model, and the interaction characteristic radius was obtained by fitting. This work can help us understand the nonlinearity phenomenon in scintillators and provide references for related radiation detection applications.

To eliminate or alleviate the water blocking effect (WBE) encountered while hydraulic fracturing of coal seams, the wettability of the coal body was changed, using gas-wetting reversal technology, thus improving gas drainage. After initial measurements of contact angles, surface tension, surface free energies, erosion resistance, self-absorption capacities, and self-absorption rates of coal samples, a hydrophobic and low-surface-tension gas surfactant was selected. After comparing the results of four candidate surfactants, two surfactants were selected, FC117 and FC134, which were both hydrophobic and exhibited low surface tension, to achieve the desired effect. Testing showed that with increased surfactant concentration contact angles increased and surface tension gradually decreased. After surfactant treatment, the coal surface energy decreased, self-absorption capacities and rates of coal samples decreased significantly, and their erosion resistance was good. After determination and verification of several evaluation parameters, the results showed that the two surfactants performed well and achieved the expected effect. By optimizing and evaluating gas-wetting reversal agents, our work has provided a theoretical basis and scientific guidelines for eliminating the WBE from coal seams, thereby facilitating gas drainage.

After being studied for years, aggressive intermediate turbine duct is being attempted to be applied in turbine design to further improve the engine-performance. With such design, the shaft could be shortened effectively. However, under the influence of the more distorted coming-flow and stronger pressure-gradient in a real engine, the flow field would be more complicated definitely. Besides that, the upstream-rotor tip-leakage flow is a key loss-source by inducing separation. Flow-control strategies are necessary in this situation. In this paper, the flow field in an aggressive duct has been analyzed to declare the source of separation primarily. Then wide-chord blade design concept has been adopted as a control strategy firstly to realize the purpose of improving the areo-performance. After being verified, numerical method has been used in this study. Under the same aero-condition, the prototype and the modified turbine are analyzed. With this novel flow-control strategy, separation has been improved, even diminished. However, the flow structures within the blade passage are altered correspondingly. An instrumental conclusion is that the pressure loss could be decreased successfully by designing the wide-chord blade specially.

As the actual jointed rock mass often does not behave elastically, its deformation modulus is typically used in practical engineering. In this study, an analytical equation for characterizing the d...

Thieno[2,3-f]benzofuran (BDF) has the advantages of a highly planarized structure, strong electron-donating ability, high hole mobility, good conjugation, and a wide spectral response range. In recent years, BDF has been widely used in organic solar cells, especially in bulk-heterojunction (BHJ) organic solar cells. In this work, a model molecule PSB-1 was synthesized based on this highly planar fragment and used as a photosensitizer in dye-sensitized solar cells (DSCs), then different aromatic amine donors such as triphenylamine (TPA), carbazole (CZ), and phenothiazine (PTZ) were introduced to the end of PSB-1, and a series of dyes PSB-2, PSB-3, and PSB-4 were designed and synthesized. After that, the relationship among the molecular structure, energy level, and photovoltaic performance of the benzo-[1,2-b:4,5-b']dithiophene (BDT) dye was studied by theoretical calculations, photophysics, electrochemistry, and photovoltaic properties. The results show that the introduction of a strong donor can effectively improve the energy level, absorption spectrum, and photovoltaic performance of PSB-1. Through the preliminary test, we found that the energy conversion efficiency (photovoltaic conversion efficiency-PCE) of PSB-4 is up to 5.5%, which is nearly 90% higher than that of PSB-1 (PCE = 2.9%), while the introduction of a weak donor greatly weakens the effect, in which the PCE of PSB-3 is 3.5%, which is only 20% higher than that of the model molecule. By an analysis of the molecular frontier orbital distribution using theoretical calculations, we found that the electron cloud of the highest occupied orbital level (highest occupied molecular orbital-HOMO) of PSB-3 is mainly distributed on the BDF group so that the electron transfer of excited-state molecules mainly occurs from the BDF to the receptor (CA).

In typical median and small aeroengines, the air used to realize the functions such as cooling of turbine blades and disks, sealing of turbine cavities and bearing chambers, adjusting of rotating assembly axial load is normally drawn through the rear cavity of centrifugal impeller, so the thorough understanding of flow characteristics and pressure distribution and the proposal of the corresponding control methods in the cavity are the key to design the rational secondary air system. With an impeller rear cavity in a small turbofan engine as an object, the current study was dedicated to the investigation of flow control methods in the cavity. Two methods, namely, baffle and swirl-controlled orifice, were proposed to regulate the pressure loss and distribution in the cavity. Furthermore, the influence of geometry parameters of the two methods such as the length of baffle, the space between the baffle and rotating disk wall, the orientation, and radial position of swirl-controlled orifice was investigated. The CFD results show that the swirl-controlled orifice which could deswirl the flow is more effective in regulating the pressure loss and its distribution in cavity than baffle. The variation of the radial position of the swirl-controlled orifice had little influence on pressure loss but obvious influence on pressure distribution; therefore, decreasing the radial position could reduce the axial load on the rotating disk without changing the outlet pressure.

In this work, utilizing a dynamic imine exchange, we develop a selective etching strategy to construct porous polymer nanosphere precursors, which can be subsequently carbonized into hierarchical porous carbon nanospheres (PCNPs) co-doped with both N and P elements. Our strategy to construct polymer precursors is simple, suitable to various aldehyde and amino building blocks and easy to incorporate heteroatoms into the carbon matrix. Importantly, by simply adjusting the concentration of the etching agent, PCNPs with micro- and meso-pores or even hollow structures can be controllably fabricated. The as-prepared PCNPs exhibit excellent electrochemical performance with the highest specific capacitances of 359.5 F g−1 at 0.5 A g−1 and 224.0 F g−1 at 20 A g−1 under acidic conditions (1 M H2SO4). The cycling stability of the PCNPs is also attractive, with a capacitance retention of ∼95% after 5000 cycles. Semi-solid-state supercapacitors assembled using PCNPs as electrodes and H2SO4/PVA as a gel electrolyte exhibit specific capacitances up to 226.7 F g−1 at 0.2 A g−1 and 126.0 F g−1 at 20 A g−1.

The shear strength of some concrete materials should be analyzed based on elastic-plastic theory in petroleum, water conservancy, tunnel engineering, and so on. The majority of researches concentrate mainly on the tensile and compressive strength of concretes, but few have studied the shear strength. Concrete materials have been increasingly applied broadly to geotechnical engineering. Thus, investigating the shear strength characteristics of concretes is of great importance. To study the characteristics of shear strength of concrete materials, the theoretical relationship between concrete’s compressive and shear strengths was discussed in the uniaxial, biaxial, and triaxial stress states. The concrete strength envelopes under the biaxial and uniaxial compressive strength were studied. Given the concrete shear strength, the overload method and the finite difference software FLAC3D were used to investigate the concrete failure modes and ultimate bearing capacities. Results show that the theoretical formula under the 3D stress-bearing condition is only applicable to the circumstance with equal compressive strengths under the biaxial and uniaxial conditions, which conforms to 3D Mohr’s circle theory. 3D Mohr’s circle theory is not totally applicable to concrete materials where the concrete compressive strength under the biaxial condition is larger than that under the uniaxial condition. Concrete material gains its shear strength 47 percent from its frictional force while the rest form cohesive force. The study results can provide a certain basis and reference for analyzing the shear strength characteristics of concrete materials.

One of the important strategies for designing pure organic dyes is to improve the electron donating abilities of dye donors hence increase the intramolecular potential energy difference. In order to quantify the electron-donating capacity of organic units, we firstly propose a parameter donation ability (DA) value for evaluating the electron DA of organic units via theoretical calculation, by using of several fragments such as coplanar dithiophenyl pyrrole, triphenylamine (TPA), phenothiazine (PTZ) and cyanoacetic acid (CA) which is the research objects here. Inspired by the DA values of the above organic fragments, dye PSD-9, PSA-10 and PST-11 were designed and synthesized. Cyclic voltammetric (CV) measurements show that the DA values of dye PSA-10 and PST-11’s donor increases when TPA and PTZ groups are introduced into PSD-9, hence HOMO level increases and the band-gap narrow down. This change is reflected in the absorption spectra: the maximum absorption wavelength of PSA-10 and PST-11 is 63 and 84 nm red-shifted compared with PSD-9. Similarly, the molar extinction coefficients of PSA-10 and PST-11 are increased by 34.7 × 103 and 14.7 × 103 M−1 cm−1, respectively. Combining a mesoporous titania film grafted by these dithiophenyl pyrrole dye with iodine electrolyte, an 4.2% and 4.8% power conversion effciency (PCE) is achieved for PSA-10 and PST-11 at an irradiance of the AM1.5G sunlight, with an significant increasing compared to PSD-9 with an PCE of 1.6%. The typical photocurrent density–voltage (J–V) test shows that the short circuit current of dye PSA-10 and PST-11 is much higher than that of PSD-9, which is the main reason for the improvement of PCE. The red-shift and stronger IPCE curve is the most advantageous evidence of the change of short circuit current. Furthermore, electrochemical impedance measurements is studied for exploring the changes of open-circuit voltage of PSA-10 and PST-11, the results infer that larger donor units and long alkyl chains can effectively increasing current density on photoanode, hence increase the open circuit voltage of the devices.

Polymer dyes have many potential advantages, such as high molecular weight, better light capture ability, thermal stability, film-forming ability, light resistance, and electrochemical corrosion resistance. They are expected to provide opportunities for the development of high-stability dye-sensitized solar cells (DSCs). However, polymer DSCs (PDSCs) have poor short-circuit current and filling factor (FF) due to polymer aggregation and chain-winding effect. Therefore, the energy conversion efficiency is low. In this work, we are trying to find a way to solve this problem. Herein, three polymers, polyPAC-01, polyPAC-02, and polyPAC-03 with different π-bridge chains were prepared on a titanium dioxide electrode using an "adsorption first, then electropolymerization (EP)" process. Meanwhile, as a comparison, three oligomers, PAC-01, PAC-02, and PAC-03 with the same skeleton were synthesized by the Suzuki coupling reaction and fabricated on a titanium dioxide electrode with a "first polymerization, then adsorption" process. Then, the photoanode adsorbed by those polymers or oligomers were applied to DSCs. The results show that polymers prepared by the EP method obtained a higher short-circuit (J sc) increase, exceeding 30% and a FF increase of about 10%, and finally, the photo-to-electric conversion efficiency (PCE) increased exceeding 40%, compared to the oligomers. In addition, desorption experiments in a harsh environment show that the EP method-synthesized polymers (polyPAC-03 as a representative) have better solvent resistance and adsorption stability than the corresponding oligomers (PAC-03). The results show that the process of "adsorption first, then EP" may be an effective way to solve the bottlenecks of low energy conversion efficiency on PDSCs and provide a new way to develop stable and efficient DSCs.

To clarify the effects of water cooling on solidification behavior of pulsed laser welding of Nickel-based alloy/austenitic stainless steel with filler wire, and to improve the mechanical properties of laser welded joints, the analyses of morphology, microstructure, anti-peel property and micro-hardness were carried out. The results indicated that adding water cooling increased cooling rate and temperature gradient of the weld. And the addition of water cooling made constitutional supercooling of the weld easier, so that the solidification rate increased with the increase of the temperature gradient. Therefore, the weld grain was refined by about 28%, and the average width of unmixed zone decreased by 35%, with a low volume fraction of Mo-rich precipitated phase consisting of p phase and μ phase. The μ phase was discovered in laser welding Nickel-based alloy/austenitic stainless. Both p phase and μ phase had a good coherent relationship with the matrix, which resulted in the low phase boundary energy between precipitated phase and matrix. The coherent relationship is described as [1 4 3] p // [5 3 1] γ between the p phase and the matrix. And the coherent relationship is described as [1 2 0] μ // [2 2 1] γ between the μ phase and the matrix. There are the stacking faults in the μ phase along the direction of [1 1 0], which is one of the slip system in μ phase. At the same time coherent relationship between p phase and matrix is better than that of μ phase. The micro-hardness, load capacity per length, and anti-peel stress were improved by 10.5%, 8.1%, and 11.8%, respectively.

In order to study the combustion characteristics in a precalciner, the temperature and composition field in a typical Trinal-sprayed calciner were numerically analysed. The results obtained by simulation were compared to actual measurements and the simulated results were in good agreement with the measured ones. The results indicated that the aerodynamic flow field in the precalciner is satisfactory, and a symmetrical reflux occurs in the shrinkage zone of the precalciner because of air staging, which can increase the residence time of the solid particles. The temperature distribution in the furnace is uniform, and the average temperature is greater than 1200 K, which can satisfy the conditions for the pulverised coal combustion and raw material decomposition. The mass fraction distribution of oxygen, carbon monoxide, and carbon dioxide in the precalciner is closely related to the temperature distribution. The concentration of nitrogen oxides (NOx) exhibits a trend of increasing, decreasing and then increasing, and finally tending to a stable level. Within a certain velocity range, the average temperature in the precalciner and the decomposition efficiency of the raw material increase as the flue gas velocity increases. When the flue gas velocity is 24 m/s, the overall performance of the precalciner is optimal.

Fatigue crack propagation is one of the main problems in structural health monitoring. For the safety and operability of the metal structure, it is necessary to monitor the fatigue crack growth process of the structure in real time. In order to more accurately monitor the expansion of fatigue cracks, two kinds of sensors are used in this article: strain gauges and piezoelectric transducers. A model-based inverse finite element model algorithm is proposed to perform pattern recognition of fatigue crack length, and the fatigue crack monitoring experiment is carried out to verify the algorithm. The strain spectra of the specimen under cyclic load in the simulation and experimental crack propagation are obtained, respectively. The active lamb wave technique is also used to monitor the crack propagation. The relationship between the crack length and the lamb wave characteristic parameter is established. In order to improve the recognition accuracy of the crack propagation mode, the random forest and inverse finite element model algorithms are used to identify the crack length, and the Dempster–Shafer evidence theory is used as data fusion to integrate the conclusion of the two algorithms to make a more accountable and correct judge of the crack length. An experiment has been conducted to demonstrate the effectiveness of the method.

Four kinds of tested fuels were prepared by adding Fe fuel-borne catalyst (Fe-FBC) to diesel at mass concentrations of 0, 100, 200 and 300 mg/kg, named as Diesel, Fe100, Fe200 and Fe300, respective...

A portable micro energy dispersive X-ray fluorescence spectrometer with Laser Displacement Sensor (LDS) is reported in this paper. Due to irregular or curved surface of archaeological object, the distances between the irradiation spot of sample and exit of polycapillary X-ray optics can vary. In this paper, we employed a LDS in our portable micro-X-ray fluorescence spectrometer to control the distances between the irradiation spot on the sample and the exit of polycapillary X-ray optics in order to decrease the errors caused by the irregular or curved surfaces of samples. In order to test this spectrometer, elemental mapping analyses were carried on with and without LDS on an irregular colored glaze of a piece of curved ancient porcelain, the height difference of two parts of ancient porcelain being nearly 5 mm. From the results, it can be concluded that this spectrometer has potential application prospects in measuring irregular or curved surface of samples.

Asbestos is widely applied in such sectors as manufacturing automobiles, tractors, chemical industrial equipment, and electric equipment. Asbestos fiber is harmful to human health. Therefore, the technology of testing for asbestos in products is especially important. At present, in our country’s national specifications, there is no determination method or specification that is applicable to the asbestos in electronic and electric products. In this article, the components of asbestos in electronic and electric products are identified using the method of combining polarizing microscope with X-ray diffractometer. This method is simple, fast, highly reliable, and suitable to be widely adopted.

The pressure-side cutback is used to design the trailing-edge film cooling. Previous studies have demonstrated the strong unsteady film mixing between the mainstream gas and the slot coolant, resulting in rapid deterioration of the film cooling effectiveness on cutback surface. The shedding vortexes formed by the clockwise and counter-clockwise structures induced by the mainstream and slot coolant shear-layer account for the strong blending. The RANS/LES hybrid turbulence model (DDES) has been proved to capture the locally unstable flows well. The flowfields and temperature of the cutback under eight blowing ratios Mslot = 0.3 ∼ 1.2 are simulated. With the increasing of blowing ratios, the counter-clockwise structures induced by the slot coolant shear-layer are strengthened to dominate the shedding vortexes gradually, which is corresponding to three kinds of coherent structures. Under low Mslot = 0.3 ∼ 0.5 dominated by clockwise structures of the mainstream, the effectiveness increases. Under middle Mslot = 0.5∼0.75 dominated by both clockwise structures of the mainstream and counter-clockwise structures of the slot coolant, the effectiveness decreases. Under high Mslot = 0.75∼1.2 dominated by counter-clockwise structures of the slot coolant, the effectiveness increases again. To weaken the blending at cutback, the pressure-side film hole with Mhole = 0.4 is arranged close to the cutback to rebuild the mainstream shear-layer. The weakened mainstream shear-layer and the assistant hitting of the hairpin vortexes from the hole injection can weaken the strength of the shedding vortexes at cutback, contributing to the improvement of the effectiveness on cutback surface under low Mslot = 0.5 and middle Mslot = 0.75. Under high Mslot = 1.0, the less influence of the hole injection on the shedding vortexes dominated by the slot coolant counter-clockwise structures accounts for slight improvement. Finally, FFT analysis is obtained for two configurations.

Both short-wave infrared (SWIR: 900-1700 nm) and near-infrared (NIR: 650-900 nm) luminescence possess lower optical scattering and higher signal-to-noise in deep tissues than conventional luminescence, gaining increasing attention in biomedicine. Herein, we designed mesoporous silica-coated Yb-doped magnesium germanate nanoparticles (mMGOs) with excellent two-in-one NIR and SWIR persistent luminescence after X-ray irradiation by simply regulating the valence of rare-earth ions, which also possess high cargo loading and a controlled release profile in the tumor region. The investigations in vitro and in vivo showed that mMGOs were repeatedly activated to realize rechargeable persistent luminescence imaging for tracking cargo delivery in mice. Moreover, the stimulative drug-release profile inhibited tumor growth effectively. Both of the X-ray excited two-in-one NIR and SWIR persistent luminescence imaging not only allowed for rechargeable imaging of deep tumors but also achieved long-term tracking with a remarkable tumor inhibition effect.

Fiber-reinforced foamed lightweight soil is a new type of material that is mixed with cement, foam, polypropylene fiber, and water, and has been applied in the reinforcement of soft soil su...

The X-ray diffraction analysis is a nondestructive phase analytical method has been widely used in archaeology, physical chemistry, geoscience and materialogy, etc.. In this study, we developed a type of X-ray diffractometer equipped with slightly-focusing ploycapillary optics and reported some new results of this instrument. By comparing the diffraction peaks of irregular surface of the RMB 5 Jiao coin in our instrument with that of X-Pert Pro MPD (PANalytical, Holland) diffractometer. The results show that our instrument can get the accurate phases but the peaks’ positions of the phases of X-Pert Pro MPD drift largely. Moreover, our instrument measured the color glaze of a piece of ancient porcelain fired in Jizhou kiln. It shows that the 3Al2O3·2SiO2 (PDF 15-0776) and Fe2O3 (PDF 25-1402) are the main crystal structures in white glaze, the black glaze is mainly composed of the Fe3O4 (PDF 28-0491) and 3Al2O3·2SiO2 and the main phase of body is 3Al2O3·2SiO2 (PDF 15-0776) and quartz (PDF 46-1045). From those results, we can understand that the white glazes are fired in a high temperature about 1250°C while the black glaze is fired in low temperature. That is helpful to understand the firing and coloring process with color glaze of ancient porcelain fired Jizhou kiln. Therefore, it can be concluded that slightly-focusing ploycapillary optics diffractometer has broader application prospects in the analysis of samples with irregular or curving surface.

In engineering, the highest operating head of the pumping station is usually controlled to be slightly lower than the lowest saddle bottom head of the axial-flow pump. However, in the practical operation, it is found that the highest operating head of the pumping station is obviously lower than the saddle bottom head of the pump device, which leads to the reduction of the operating range of the pumping station. To investigate the difference of lowest saddle bottom head between axial flow pump and axial flow pump device and apply it correctly, the energy performance tests of the TJ04-ZL-06 hydraulic model and its corresponding pump device were carried out to obtain the external curves, and numerical simulation was carried out to analyze and compare the internal flow field and pressure distribution. The results show that when the flow rate decreases, the first saddle-shaped region of the axial-flow pump and the saddle-shaped region of the pump device are caused by the decrease of the lift coefficient due to the increase of the attack angle between flow and blade. When the flow rate is less than 0.32Qd, the influence range of backflow in the inlet pipe is large, which leads to the high-pressure zone near the wall of the inlet pressure measurement section during the pump performance test, and hence the second saddle-shaped region of the axial-flow pump is essentially a measurement illusion. It is suggested that the inlet pressure measurement section should be set at least 4Dp away from the inlet flange of the impeller when testing the performance of the axial-flow pump under the condition of small flow rate, and the first saddle bottom head of the axial-flow pump or the saddle bottom head of the corresponding pump device can be considered as the control value of the highest head of the pumping station.

The trailing edge cutback is often applied when designing the film cooling structure of a high-pressure turbine. Previous studies have demonstrated strong unsteady film mixing process which is indeed influenced by the vortex shedding from the pressure side lip. Thus, adiabatic film cooling effectiveness on cutback rapidly declines at streamwise direction. To obtain high film cooling performance, this paper arranges a cylinder hole on pressure side upstream of the trailing edge cutback flat-plate model. The film cooling characteristics of combined configuration are investigated with unsteady numerical method. DES turbulence model has been proved to capture the vortex shedding well. The mainstream Reynold number is Rem = 360000 based on the length from inlet to lip. The total coolant-to-mainstream blowing ratio is M = 0.5 and cylinder hole is arranged at three different positions (X/H = −4, −6, −8). Firstly, film cooling performance of two configurations (cutback, cutback with a cylinder hole at X/H = −6) are compared. The results indicate that the mainstream temperature and velocity greatly reduce due to hole coolant ejection. The vortex shedding downstream of lip is weakened contributing to less film mixing on the trailing edge cutback. The lateral-averaged adiabatic film cooling effectiveness increases especially downstream of cutback. Then three combined configurations of hole at different positions show that all configurations can improve film cooling performance of the trailing edge cutback. When cylinder hole is arranged closer to lip, adiabatic film cooling effectiveness increases more.

RF PA is required to have sufficient reliability to protect them from mismatch. In this paper we present the RF characterization of Gallium Arsenide heterojunction bipolar transistor (GaAs HBT) transistors under load mismatched conditions. The mismatch test is carried out on an real-time active load-pull system with load mismatch of voltage standing-wave ratio (VSWR) of 10: 1. It is found that the 1-dB compressed RF output power (1 dB), transducer gain (G T ), and power-added efficiency differ by 5 dBm,6dB, and 15%, respectively, between the optimal and worst phase conditions. This characterization method allows for a non-destructive way of monitoring of the device ruggedness and can be used in both manufacturing and device design stages.

It was well recognized that the voltage type has a significant influence on the sample behaviour in the inclined-plane test. Generally, under the same voltage level and contaminant flow rate, the degree of material degradation in the DC test was more severe than that in AC test. And the material behaves the worst in the positive DC test. The amplitude of arcing current usually follows $I$ (+) > $I$ (∼) > $I$ (-). At present, there is no widely accepted explanation on these phenomena. In this paper, the difference between the arcing current of positive and negative half cycles in the AC inclined-plane test was analyzed. Then three types of metal materials with different work functions, i.e. aluminum, stainless steel and copper, were used as the bottom electrode. The influence of work function of the bottom electrode material on the difference between positive and negative half cycles and the material degradation was then studied. The results indicated that electron emission by cathode material should be one of the reasons of larger arcing current and more severe material degradation in positive DC tests. The findings could also explain the observation that material degradation of the specimen under negative DC voltage was more severe than that under positive DC voltage in tracking and erosion tests on composite insulators (such as tracking wheel test, 1000 h salt fog test and 5000 h test).

As the material for shed and sheath of composite insulators, HTV silicone rubber faces multiple stresses in the serving environment, in which water permeation may lead to degradation and harm the cores. This research studied in the dielectric response of HTV silicone rubber samples which have been immersed into deionized water, and analyzed the test results with Dissado-Hill loss peak model and QDC model. Both real and imaginary parts of the dielectric response increased after immersed for 400h. The fitting results showed that the QDC phenomenon was more obvious after long time immersion. Water promoted the number of charges which participated in the hopping process, and offered path for the hopping process in QDC. Meanwhile, water invading made the interfaces loose and led to disorder of the structure. These results prove that water permeation is highly likely to be the reason of chalking on the shed and sheath of composite insulators.