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Herein, the evolution of reduction process of ultrafine tungsten powder in industrial conditions was investigated. The transition process of morphology and composition was examined via SEM, XRD, and calcination experiments. The results show that the reduction sequence of WO2.9 was WO2.9 → WO2.72 → WO2 → W on the surface, but WO2.9 → WO2 → W inside the oxide particles. With the aid of chemical vapor transport of WO x (OH) y , surface morphology transformed into rod-like, star-shaped cracking, floret, irregularly fibrous structure, and finally, spherical tungsten particles.

To extend the modeling area with artificial neural networks (ANNs) from finite periodic arrays to thinned arrays, where spacings between adjacent elements are crucial for array performance, an efficient model is proposed in this letter. Considering the spacings, a novel hidden node interconnection-radial basis function neural network (HNI–RBFNN) is developed to map the relationship between the array electromagnetic (EM) responses and the element ones. The element EM responses are obtained with the traditional RBFNN only involving the element geometry, while the connected weights of hidden layer nodes are determined by mutual coupling and array environment with the HNI scheme. A numerical example of the thinned phased array is used to evaluate the validity of the proposed model.

Two new metal-organic coordination compounds with the chemical formulae of [Zn(Htpt)]n (1) and {[Zn(H2tpt)(H2O)]·1/2SO4·2H2O}n (2) based on a multidentate 4-(2,4,6-tricarboxyphenyl)-2,2′,6,2″-terpyridine ligand (H3tpt) have been prepared by hydrothermal synthesis method and structurally characterized. The treatment activity of the compounds on the peripheral artery disease was further explored in the biological section. Firstly, the real time reverse transcription-polymerase chain reaction (RT-PCR) was performed and the expression levels of the peptidyl arginine deiminase were measured. Then, the enzyme linked immunosorbent assay (ELISA) detection kit was used and the content of the inflammatory cytokines was determined. Two new metal-organic coordination compounds have been prepared by hydrothermal synthesis method. The treatment activity of the compounds on the peripheral artery disease was further explored in the biological section. Firstly, the real time reverse transcription-polymerase chain reaction (RT-PCR) was performed and the expression levels of the peptidyl arginine deiminase were measured. Then, the enzyme linked immunosorbent assay (ELISA) detection kit was used and the content of the inflammatory cytokines was determined.

For wide-angle scanning phased arrays, the efficiency of active elements is deteriorated with the increase of mutual impedance. This article demonstrates an effective strategy to control the mutual impedance among array elements by canceling the major coupling effect. The implemented wide-angle impedance matching (WAIM) of a wideband phased array verifies the validity of the proposed strategy. For the array element, to obtain wide-angle radiation and wideband characteristic, parallel slots with unequal lengths are deliberately etched on a low-profile substrate integrated cavity (SIC). The mutual impedance between two arbitrary elements is remarkably controlled and compensated by canceling the major coupling effect, which is realized by etching symmetrical slots and loading periodical loops within each element. With the controlled mutual impedance, the proposed array possesses excellent wide-angle scanning performance. Both the simulated and measured results indicate that the designed array steers its main beam from −70° to +70° in the xoz azimuth plane in a broad frequency range from 8.0 to 9.5 GHz. The active $S$ -parameter of each element remains lower than −10 dB in the operating band while the array scans. Due to the implemented WAIM, the total efficiency of the array exceeds 90% during the scan and the fluctuation of realized gain is less than 3 dB.

A new triazine charring agent, melamine formaldehyde resin modified with pentaerythritol (named as MF-MPOL), was synthesized through hydroxymethylation, condensation and etherification by using melamine, paraformaldehyde and pentaerythritol as raw materials, and characterized by solid-state 13C NMR and FT-IR. The intumescent flame retardant (IFR) consisting of MF-MPOL with ammonium polyphosphate has good flame retardancy in polypropylene (PP). The analysis of the residues obtained in cone calorimetry test showed that the IFR played a role of flame retardancy mainly in condensed phase. In other words, the porous and dense - continuous intumescent char layer formed during the burning process results in flame retardant effect by insulation of heat, oxygen and preventing the underlying PP from degradation and volatilization of pyrolytic products.

To make metasurface design faster and more convenient, a new inverse extreme learning machine (ELM) is proposed in this letter. Compared with the traditional forward model based on artificial neural networks, the proposed inverse ELM uses a small number of training samples to meet the modeling standard, and it directly obtains the satisfying geometry without an optimization process. Meanwhile, to enhance the modeling performance, the data classification technique and a cascade of two ELMs are contained in the tailored scheme, where the second ELM is applied to error correction. A numerical example of an interdigital resonator metasurface is employed to verify the effectiveness and efficiency of the proposed model.

In this work, two Cu(II)-containing coordination polymers, namely, {[Cu2(L)2(dpyb)(H2O)4]·6H2O}n (1) and {[Cu2(L)2(dpyb)](CH3CN)2}n (2) have been hydrothermally synthesized based on a substituted t...

Two Cu(II)-based coordination polymers with the chemical formula of [Cu(bibb)(1,4-NDC)](DMF) (1, bibb = 1,4-bis(benzimidazol-1-yl)−2-butylene, 1,4-H2NDC = 1,4-naphthalenedicarboxylic acid, DMF = N,...

To alleviate the nonuniform error distribution and slow convergence caused by the uncertainty of sample selection in the training process of artificial neural networks, a semisupervised radial basis function neural network (SS-RBFNN) model with a new sampling strategy is proposed for parametric modeling of microwave components in this article. After evaluating the current training performance, the new sampling strategy selects suitable training samples to ensure each subregion of the whole sampling region with the same level of training and testing accuracy. Meanwhile, the proposed SS-RBFNN simplifies the modeling process to further enhance the modeling accuracy and efficiency. Two numerical examples of a slow-wave defected ground structure dual-band bandpass filter and a microstrip-to-microstrip vertical transition are employed to verify the effectiveness of the proposed model.

Two new three-dimensional (3 D) cobalt-based coordination polymers [Co(L)(5-hypa)]n (1, H2hypa = 5-hydroxyisophthalic acid), and [Co(L)(1,4-NDC)]n (2, 1,4-H2NDC = naphthalene-1,4-dicarboxylic acid)...

Interfacial modification is one of the most important technologies to improve the overall electrochemical properties of Ni-rich cathodes. Herein, a novel strategy of in situ planting of an electrolyte film-forming additive on a single crystal NCM811 surface is proposed by consuming the residual lithium to develop a functional Al(Li)BOB nano-layer. Different from traditional physical coating, this approach cleverly consumed the undesirable residual lithium on the NCM811 surface. The in situ grown 30–50 nm Al(Li)BOB layer on the single crystal NCM811 cathode surface contributes to its much enhanced electrochemical performances. At a high operating voltage (charge voltage limit of 4.5 V vs. Li/Li+), the capacity retention is greatly increased from 57.0% to 83.5% after 295 cycles. Meanwhile, the incorporation of aluminum is effective in improving the thermal stability of the Ni-rich cathode. The novel interfacial strategy by in situ implanting of an electrolyte additive is of important significance for solving the critical interfacial issue for Ni-rich cathode materials.

By employment of the mixed-ligand approach, a new Co(II)-based coordination polymer with the chemical formula of [Co(ox)(ditb)] (1, ox = oxalic acid, ditb = 1,4-di(1H-1,2,4-triazol-1-yl)but...

In this paper, an effective method aimed at reducing the mutual impedance among array elements is developed to realize wide-angle impedance matching (WAIM) for planar phased arrays. According to the property of the coupling field, the inherent field distribution at apertures of each element is properly regulated so that the mutual impedance between two arbitrary elements can be substantially reduced. Based on the analysis of the impedance matrix for the equivalent microwave network, the required WAIM can be implemented with such minified mutual impedance. With the proposed method, a low-profile linear phased array with $1 \times 10$ uniform elements is designed and manufactured. For the presented array, the wide-angle scanning performance is attained from the joint effect of the spatial radiation and the surface-wave diffraction. To achieve WAIM, the inherent field of each element is deliberately adjusted according to the distribution of the guided TM surface wave, which acts as the dominant coupling field. Both simulated and experimental results indicate that the proposed phased array can steer its main beam from −81° to +81° in the azimuth plane, with peak realized gain fluctuation less than 3.5 dB. Particularly, besides the broad range of scan, all the active S-parameters are controlled less than −10 dB in the fixed operating band for all scanning angles.

Based on critical plane approach, this paper develops a new damage parameter through combing the equivalent strain energy aspect for multiaxial fatigue analysis, which includes no additional parameters and overcomes the deficiency of using only equivalent stress/strain criterion separately under multiaxial loadings. Then, experimental data of GH4169, TC4, Al 7050-T7451 alloys under different loading conditions are applied for model validation and comparison with the other four models. Results indicate that the proposed damage parameter yields better multiaxial fatigue life predictions than others.

A valley photonic crystal is one type of photonic topological insulator, the realization of which needs only P-symmetry breaking. The domain wall between two valley-contrasting photonic crystals supports robust edge states, which can wrap around sharp corners without backscattering. Using the robust edge states, one can achieve pulse transmission. Here, using time-domain measurements in the microwave regime, we show distortionless pulse transmission in a sharply bended waveguide. An \ensuremath{\Omega}-shaped waveguide with four 120\ifmmode^\circ\else\textdegree\fi{} bends is constructed with the domain wall between two valley photonic crystal slabs. Experimental results show the progress of Gaussian pulse transmission without distortion, and the full width at half maximum of the output signal changes slightly in the \ensuremath{\Omega}-shaped waveguide. By measuring the steady-state electric field distribution, we also confirm the confined edge states without out-of-plane radiation, which benefits from dispersion below the light line. Our work provides a way for high-fidelity optical pulse signal transmission and the development of high-performance optical elements, such as photonic circuits or optical delay lines.

Here, the frequency degree of freedom is introduced into valley photonic crystals with dual band gaps. Based on the high-order plane wave expansion model, we derive an effective Hamiltonian which characterizes dual band gaps. Metallic valley photonic crystals are demonstrated as examples in which all four topological phases are found. At the domain walls between topologically distinct valley photonic crystals, frequency-dependent edge states are demonstrated and a broadband photonic detouring is proposed. Our findings provide the guidance for designing the frequency-dependent property of topological structures and show its potential applications in wavelength division multiplexers., Comment: 12 pages, 4 figures

Deep eutectic solvents (DESs) have attracted an increasing attention in the fields of biocatalysis and biopolymer processing. In this study, papain immobilized on choline chloride- lactic acid (ChCl-Lac) DES-treated chitosan exhibited excellent thermostability as compared to the free enzyme. The properties of native or DES-treated chitosan and immobilized enzyme were characterized by FT-IR, SEM, surface area and pore property analysis. Like the common enzyme immobilization, papain immobilized on DES-treated chitosan resulted in a lower catalytic efficiency and a higher thermostability than the free enzyme due to the restricted diffusion. The results also revealed that DES could control the active group content, thus achieving the appropriate microporous structure of immobilized enzyme. Meanwhile, it could also help to construct the optimal microenvironment by hydrogen-bonding interaction between enzyme, chitosan, and residual DES, which are benefit for maintaining an active conformation and subsequently a high thermostability of papain. Moreover, it was found that trace DES (10 mM) significantly promoted the activity of free papain (145%). Deactivation thermodynamics study showed that the DES could enhance the thermostability of papain especially at high temperature (half-life of 7.4 vs. 3.5 h) because of the increased Gibbs free energy of denaturation. Secondary structure analysis by circular dichroism spectroscopy (CD) agreed well with the activity and thermostability data, further confirming the formation of rigid conformation induced by a specific amount of DES. This work provides a new way of enzyme immobilization synergistically intensified by solvents and supporting materials to achieve better microporous structure and catalytic microenvironment.

Melt strength is crucial in foam-processing of polymer materials, especially for linear molecular structured isotactic polypropylene (iPP), which has comparatively weak melt strength to hinder its foaming. In this study, a commercial high melt strength polypropylene (HMSPP) was added into the iPP matrix, cooperated with a thermal treatment, aiming to enhance the melt strength and microcellular foamability of iPP under supercritical CO2. Melt strength enhancement effect was proved by rheological and microcellular foaming results. The crystallization and batch foaming behaviors of iPP and its HMSPP added blends at different foaming conditions were investigated. It was observed that the addition of HMSPP could refine the crystals of the blends, and the crystal nucleation sites could be increased apparently. Cooperated with the suitable thermal control schedule during the batch foaming process, the introduced crystals could correspondingly improve the melt strength and cell nucleating ability of HMSPP added iPP. At a given HMSPP content of 20 wt.%, quite fine microcellular foams with the average cell size of 0.8 μm, and cell density up to 1012 cells/cm3 were fabricated.

Homogeneous columnar Cu film with fully embedded nanotwins was successfully fabricated on Ti/Cu seed layer on silicon wafer. The nanotwins with thickness of tens of nanometers are generally parallel to the silicon surface, showing a strong (111) preferred orientation. The acid concentration was found to be important in influencing the formation of nanoscale twins. By adjusting the acid concentration, the nanotwins can be induced from the top columnar grain to middle columnar grain and reach the bottom equiaxed grain, and a microstructural transformation model was given. A theory focusing on the cathode overpotential was proposed to reveal the effect of acid concentration on the growth mechanism of nanoscale twins. An appropriate adsorption proportion of hydrogen on cathode (acid concentration 17 ml L−1) could increase the overpotential which supplies adequate nucleation energy for nanoscale twins formation.

In-depth understanding of interfacial behavior between biopolymer and semiconductor metal oxides is crucial to developing potential applications of their composites. A structure-ordered cellulose/zinc oxide composite was synthesized and systematically examined by a relativistic density functional theory. The prepared composite shows a hierarchical structure. ZnO nanoparticles of around 30 nm in size are found to uniformly grow along the cellulose fiber, which together construct the primary-structure unit. Associated with experimental characterizations, calculations unravel that the electrostatic attraction between cellulose and ZnO is the main driving force to form the primary structure and the subsequent electron transfer from cellulose to ZnO enhances their interfacial interaction; moreover, an exothermic process was computed. The interfacial interaction is mainly contributed by Zn-Oc (Oc denotes the cellulose oxygen atom), which is intrinsically of a dative bond; the interaction was calculated between −1.39 and −1.83 eV in strength and dominated by orbital attractions.

We report new insights into the solder wettability degradation of Sn thin films on Cu under 155 °C isothermal ageing. A multiscale wettability degradation model was established, reflecting quantitatively the surface oxidation and interfacial intermetallic compound (IMC) growth, on the basis of solder wetting behaviour. The thermal oxidation of Sn exhibited heterogeneous inward thickening, lateral expanding and outward platelet-like growth, forming nanocrystalline, oxygen-deficient SnO2 with pronounced voiding/cracking propensity. Unlike a commonly held belief that the initial wettability loss is due to surface-exposing and oxidation of IMCs, it was found from dual combined effects of inward surface oxidation and outward IMC growth.

In this communication, a novel artificial neural network (ANN) model is proposed to describe the antenna performance with various parameters. In this model, three parallel and independent branches are involved for three different performance parameters. Meanwhile, a data-classification technique of support vector machine is also included to classify geometrical variables into the proper categories. Once the geometrical variables are input, the ANN model can simultaneously obtain S-parameter, gain, and radiation pattern from the independent branches. The validity and efficiency of this proposed model are confirmed with a Fabry-Perot resonator antenna example.

Flood peaks and volumes had been detected a downward trend in Fuping hydrological station. To quantify the effects of check dams on flood peaks and volumes, a hydrological model integrating land use was established. The model performed well in flood processes simulation, and the Nash efficiency of the model was 0.72. Then the model was used to identify the comprehensive effects of land use and land cover change on flood processes by comparing the simulation results of the selected flood events under 1980 and 2000 land use and land cover conditions. 24.5, 37.7 and 51.3% decrease in flood peaks for flood events of greater than 10 years, 5~10 years and less than 5 years return periods, respectively, and 16.3, 27.9 and 28.5% decrease in flood volumes for the three groups flood events of different return periods. Contributions of land use change and check dams to decrease in flood peak and volume were simulated, and it was found that peak discharge and volume for each flood event responded differently to the two factors. The results in this study can provide valuable information on design flood calculation in the basin under land use and land cover change.

A surface-wave-based endfire antenna with an enhanced impedance bandwidth is presented in this paper. The antenna consists of a surface-wave guide (SWG) and five strips printed on the SWG. The endfire radiation benefits from the surface-wave diffraction of the SWG which is investigated with the Snell's law, effective surface impedance and eigenvalue analysis. A prototype is fabricated and measured, and the measured results indicate that the antenna has two resonances and its bandwidth is enhanced up to 16.1% (4.0–4.73 GHz). The proposed endfire antenna also exhibits high gain, good gain flatness, low cross-polarization level and low profile.

Based on state observation, a rapid, stable, and effective control algorithm for magnetorheological elastomer (MRE)–based dynamic vibration absorbers (DVAs) applied to automobile powertrain mount systems is proposed and investigated in this article. The state-space model for powertrain mount systems with MRE-based DVAs is established using the rank criterion method for observable systems. According to the principle of system reconfiguration, a full state observation model using an adaptive Kalman filter with Sage–Husa noise estimator is developed. With the state vectors estimated by the Kalman filter, the phase difference between the displacement of the dynamic mass of the MRE-based DVA relative to the powertrain and the absolute displacement of the powertrain is updated continuously based on Simpson’s rule. By adjusting the applied current to the MRE-based DVA with fuzzy logic control corresponding to the cosine value of the phase difference, the natural frequency of the MRE-based DVA could track the excitation frequency of the powertrain well, which results in vibration attenuation of the powertrain mount system. With consideration of excitation noise, time delays, and parametric uncertainties, the simulation experiments of vibration attenuation performance of the MRE-based DVA for the powertrain mount systems when under time-varying excitation are carried out to verify the effectiveness and the stability of the proposed algorithm with fuzzy steps. The simulation results show that when using the proposed algorithm with fuzzy steps, the MRE-based DVA could attenuate the powertrain vibration rapidly and effectively, and the vibration attenuation performance will not be influenced by noise, time delays, and parametric uncertainties.

Summary A site‐specific xenon plasma focused ion beam preparation technique for microcantilever samples (1–20 µm width and 1:10 aspect ratio) is presented. The novelty of the methodology is the use of a chunk lift‐out onto a clean silicon wafer to facilitate easy access of a low‐cost probe type indenter which provides bending force measurement. The lift‐out method allows sufficient room for the indenter and a line of sight for the electron beam to enable displacement measurement. An electroplated nanotwinned copper (NTC) was cut to a 3 × 3 × 25 µm microbeam and in situ mechanically tested using the developed technique. It demonstrated measured values of Youngs modulus of 78.7 ± 11 GPa and flow stress of 0.80 ± 0.05 GPa, which is within the ranges reported in the literature. Lay Description In this paper a site specific method is present for making particularly small mechanical tests samples, of the order of 100th the size of a human hair. These small samples can then be used to determine the mechanical properties of the bulk material. Copper with a nano twinned grain structure is used as a test medium. Ion milling was used to cut the sample to shape and a micro probe was used for mechanical testing. Ion milling can cut away very small volumes of material as it accelerates ions at the surface of the sample, atomically machining the sample. Micro probes are a cost‐effective small‐scale load measurement devices, however, they require a large area for accessing the sample. The indenter requirements are a problem when making you samples with ion milling as ion millers are best at making small cuts. Our aim was to design a cutting strategy which reduces the amount of cutting required while allowing samples to be fabricated anywhere on the sample. We used a chunk lift out technique to remove a piece of material which is then welded to a wafer of silicon this gives sufficient space around the sample for ion milling and testing. The additional space allowed easy access for the probe. A 3 × 3 × 10 µm micro cantilever beam was cut out from copper, this beam was then bent. The force from bending and distance bent was measured and converted into Youngs modulus which is a measure of flexibility. The modulus value measured was comparable to the values reported in other papers.

Based on the sub-gridding scheme, in this paper, a hybrid method including explicit finite-difference time-domain (FDTD) and implicit Crank-Nicolson (CN) FDTD is proposed for efficient time reversal (TR) simulation in an indoor environment. The whole computational program can be run with a common time step determined by the coarse grid in a stable fashion since CN-FDTD is unconditionally stable and its time step can be set to a large value. A numerical example of TR wave propagation in an electrically large environment is included to validate the accuracy and efficiency of the proposed method.

A surface wave-based planar endfire antenna with wideband performance is presented. Surface waves are excited and supported to propagate in a required direction in a surface-wave guide (SWG)-high impedance surface (HIS) hybrid structure. Four surface-wave modes are excited, and thus the antenna resonates at 4.5 and 5.5 GHz. The proposed antenna supports a operation band from 4.08 to 5.72 GHz and the realized gains in a range of 5.75 ~ 7.05 dBi.

A new type of Butler matrix-fed two-dimensional (2-D) beam scanning antenna array using composite right/left-handed (CRLH) substrate integrated waveguide (SIW) leaky-wave antennas (LWAs) technique is proposed. It consists of 4 CRLH SIW LWAs and a wideband feeding Butler matrix as the beam forming network. The proposed array can scan its beams in two dimensions by changing the operating frequency and the input port of the Butler matrix (BM), respectively. The array is fabricated and measured. The main beams can scan in one plane from -60° to 66° continuously by sweeping frequency from 3.7 GHz to 4.7 GHz. In the orthogonal plane, it can point to 4 discrete angles (-36°, -12°, 16°, 36°) by feeding in the different input port of the BM. With a wider coverage of the upper half-space, the low cost, and the low profile, this proposed antenna array is very attractive for a variety of phased array applications, particularly those that require a flush-mounted structure.

An ultralow-profile (about 0.017 λ 0 ) phased array based on substrate integrated waveguides (SIWs) is proposed for wide-angle scanning. The bandwidth is improved by etching unequal slots on the SIW of the array element. To mitigate impedance mismatch of the active element during the scanning process, an effective mutual coupling compensation network is connected to the feeding lines of the array. With the improved bandwidth and compensated mutual coupling, the phased array scans from −65° to +65° in the azimuth plane from 9.8 GHz to 10.2 GHz with realized gain fluctuating less than 2.5 dB.

Wind speed forecasting with artificial neural networks (ANNs) plays important role in safely utilizing and integrating the wind power. With the rapid updated wind speed data, however, the only way to guarantee forecasting accuracy for these ANN models is re-training from scratch with an updated training dataset. Obviously, it is an inefficient work due to the resumption of constructing the new training dataset and re-training the model. To enhance training efficiency, reduce re-training cost and improve forecasting accuracy, a self-adaptive kernel extreme learning machine (KELM) is proposed in this paper. With an advanced and efficient learning process, the self-adaptive KELM could simultaneously obsolete old data and learn from new data by reserving overlapped information between the updated and old training datasets. To evaluate the efficiency and accuracy of the self-adaptive KELM, the wind speed data from three different stations are employed as a numerical experiment. The Mean Absolute Error (MAE), Mean Square Error (MSE) and Mean Absolute Percentage Error (MAPE) showed that the self-adaptive KELM with a simple structure could obtain more accurate forecasting results at a faster calculation speed than comparison models, where the proposed model decreased the MAPE values with 7.4776%, 3.5329% and 2.0900% in 1-step, 3-step and 5-step forecasting, respectively

Supersonic gas-jet target performs an important role in laser wakefield acceleration, and its density diagnosis is a significant part of target characteristic study. In this paper, a Mach–Zehnder and Nomarski interference system is set up and used for gas-jet target density diagnosis. We have investigated and compared the performance of the Mach–Zehnder part and Nomarski part. The feasibility of the Nomarski interferometer with vertical fringes has been verified. Moreover, it shows better stability and has a more compact structure, beneficial for obtaining more accurate and effective target density characterization in laser wakefield acceleration.

This article proposes and validates the principle of a new magnetorheological elastomer (MRE) dynamic vibration absorber (DVA) for powertrain mount systems of automobiles. The MRE DVA consists of a vibration absorption unit and a passive vibration isolation unit. The vibration absorption unit composed of a magnetic conductor, a shearing sleeve, a bobbin core, an electromagnetic coil, and a circular cylindrical MRE is utilized to absorb the vibration energy, and the passive vibration isolation unit is used to support the powertrain. The finite element method is employed to validate the electromagnetic circuit of the MRE DVA and obtain the electromagnetic characteristics. The theoretical frequency-shift principle is analyzed via the established constitutive equations of the circular cylindrical MRE In order to demonstrate how the parameters of the MRE influence the vibration attenuation performance, the MRE DVA is applied to a powertrain mount system to replace the conventional passive mount. The frequency-shift property of the vibration absorption unit and the vibration attenuation performance of the MRE DVA on the powertrain mount system are experimentally tested. To validate and improve the vibration attenuation performance for the semi-active powertrain mount systems, an optimal variable step algorithm is proposed for the MRE DVA and numerical experiments are carried out.

High energy γ-ray can be used in many fields, such as nuclear resonant fluorescence, nuclear medicine imaging. One of the methods to generate high-energy γ-ray is nuclear resonant reaction. The 19F (p,αγ) 16O reaction was used to generate 6.13-MeV γ-ray in this work. The angular distribution of 6.13-MeV γ-ray was measured by six LaBr3 detectors. The thick-target yield curve of 6.13-MeV γ-ray had been measured. The maximum yield was determined to be (1.85 ± 0.01) × 10−8 γ/proton, which was measured by HPGe detector and LaBr3 detector. The absolute efficiency of all the detectors was calibrated using 60 Co and 27Al (p,γ) 28Si reaction at E p = 992 keV. The cross section and total resonant width of the reaction were determined to be 95.1±1.0 mb (1 b = 10−24 cm2) and Γ CM = 2.21±0.22 keV, respectively.

A novel AIE active dual-channel coumarin derivatives, chemosensor G1, was synthesised and used for detecting Fe3+ (in water solution) in DMSO/H2O (1:9, v/v, pH = 7.2) binary solutions, which induced the colour of solution of G1 from yellow to shallow orange and increased the fluorescence emission, indicating that G1 could act as a corking colorimetric and “turn-on” fluorescence probe for detecting Fe3+. What’s more, sensor G1 has good anti-interference toward Ca2+, Hg2+, Cu2+, Ag+, Cd2+, Co2+, Ni2+, Mg2+, Pb2+, Zn2+ and Cr3+. Notably, the actual usage of sensor G1 was further demonstrated by logic gates and test kits.

The effects of a partially melted crystal structure (PMCS) on enhancing the cell nucleating behavior, as well as on the related foaming behavior of isotactic polypropylene (iPP), were investigated. The incorporation of PMCS and the corresponding effects were characterized by rheological, thermal and X-ray testing methods. The microcellular foaming results revealed that the addition of PMCS could dramatically increase the melt strength and the cell nucleating sites of the matrix. The synergistic effects of the PMCS and high melt strength polypropylene (HMSPP) could decrease the average cell size to approximately 2 μm and increase the cell density to 1.49×1011 cells/cm3. Additionally, the gradual melting of the PMCS could also prove its enhancing effect on the melt strength and cell nucleating ability. The uniform microcellular cells obtained could positively affect the notched impact strength of the foamed iPP-HMSPP blends.

In photonic systems, exploring the valley degree of freedom (due to the presence of a local extremum in band structure in momentum space) is interesting for application of the photonic Hall effect, robust delay lines, and perfect outcoupling refraction. This work demonstrates that electromagnetic flow in a photonic-crystal waveguide can be tuned using this topological degree of freedom. Both tunable excitation of valley bulk states and tunable valley-dependent edge-state dispersion are shown. These results may impact the dynamic modulation of light in devices.

With the valley degree of freedom, we demonstrate the unidirectional propagation of bulk states and topological transport of edge states in a photonic crystal waveguide.

Temperature rise is a significant factor influencing microstructure during (α + β) deformation of TA15 titanium alloy. An experiment was designed to explore microstructure evolution induced by temperature rise due to deformation heat. The experiment was carried out in (α + β) phase field at typical temperature rise rates. The microstructures of the alloy under different temperature rise rates were observed by scanning electron microscopy (SEM). It is found that the dissolution rate of primary equiaxed α phase increases with the increase in both temperature and temperature rise rate. In the same temperature range, the higher the temperature rise rate is, the larger the final content and grain size of primary equiaxed α phase are due to less dissolution time. To quantitatively depict the evolution behavior of primary equiaxed α phase under any temperature rise rates, the dissolution kinetics of primary equiaxed α phase were well described by a diffusion model. The model predictions, including content and grain size of primary equiaxed α phase, are in good agreement with experimental observations. The work provides an important basis for the prediction and control of microstructure during hot working of titanium alloy.

This paper is the first to report a large-scale directcurrent electrodeposition of columnar nanotwinned copper within through silicon via (TSV) with a high aspect ratio (~4). With this newly developed technique, void-free nanotwinned copper array could be fabricated in low current density (30 mA/cm2) and convection conditions (300 rpm), which are the preconditions for copper deposition with a uniform deep-hole microstructure. The microstructure of a whole cross-section of deposited copper array was made up of (111) orientated columnar grains with parallel nanoscale twins that had thicknesses of about 22 nm. The hardness was also uniform along the growth direction, with 2.34 and 2.68 GPa for the top and bottom of the TSV, respectively. The gelatin additive is also first reported hereas a key factor in forming nanoscale twins by adsorbing on the cathode surface, in order to enhance the overpotential for cathodic reaction during the copper deposition process.

Edge states of photonic crystals have attracted much attention for the potential applications such as high transmission waveguide bends, spin dependent splitters and one-way photonic circuits. Here, we theoretically discuss and experimentally observe the deterministic edge states in checkerboard photonic crystals. Due to the self-complementarity of checkerboard photonic crystals, a common band gap is structurally protected between two photonic crystals with different unit cells. Deterministic edge states are found inside the common band gap by exploiting the Zak phase analysis and surface impedance calculation. These edge states are also confirmed by a microwave experiment., 13 pages, 4 figures

A multi-objective robust optimization scheme for the powertrain mount system of an electric vehicle is proposed in this paper. A permanent magnet synchronous motor model is established by taking account of the effects of magnetic saturation and space harmonics, in which the d–q-axis inductance and the flux linkage excited by permanent magnet were obtained by finite element method. The rippled output torque of the permanent magnet synchronous motor mixed with harmonic components is obtained with the New European Driving Cycle as the running condition of the electric vehicle. A six degree-of-freedoms (DOFs) powertrain mount system is established and the response of the system is obtained with the rippled torque as the excitation input. A multi-objective optimization model of the powertrain mount system is built with the stiffness’s of the mounts as the design variables, and with the goal of maximizing the decoupling rates and minimizing the dynamic reaction forces of the mounts acting on the car body. Genetic algorithm is used to conduct the global optimization and all the Pareto optimal solutions are found out based on the optimization theory, and the solution with the optimal robustness of dynamic reaction force is obtained by Latin hypercube sampling method. The results show that with the proposed multi-objective robust optimization scheme applied for the parameters optimization of the motor mount system, the decoupling rates increase obviously, the dynamic reaction force decreases apparently, and the optimization result shows good robustness. The optimization results can make the powertrain mount system of electric vehicles processing of optimal dynamic response characteristics correspondingly.

In this paper, the growth behavior of twin boundary in plated copper film was thoroughly investigated using SEM and TEM to facilitate its application as under bump metallization (UBM). The bath consisting of different amounts of H2SO4 was adopted to individually study the influence of pH on cross-sectional microstructure of copper film. Increasing the sulfuric acid concentration could greatly increase the nanoscale twin formation and make it nucleate and grow from sites much nearer the wafer. Besides, nanoscale twins were only observed in columnar grains rather than equiaxed crystallites. The growth rate of copper film was found to be enhanced with acid amount, and it was found that the stacking faults rise consequently which contributed to the nucleation and extension of the nanoscale twins. The unevenly distributed acid concentration in the bath could “recrystallize” the columnar grains into equiaxed grains, and nanoscale twins were transformed into low density of thick “annealed twins”. This could illuminate why columnar grains form ahead of equiaxed grains and coherent twin boundaries nucleated in columnar grains repetitively along the growth direction. Here, the influence of sulfuric acid was first confirmed to be the essential factor in nanoscale twin formation and this may show a distinct insight into nanotwinned copper fabrication and promote its application.

During construction, bridge’s stress state is significantly different from that in finished stage. The stress state of construction process may be much more danger when incremental launching method is applied. To analyze differences between the stress state of finished state and that in construction process, mechanical calculation was conducted based on an actual integral incremental launching constructed long-span pre-stressed composite concrete box girder with corrugated steel webs, applying solid-shell model to elaborately explore mechanical characteristics in each stage. Research reveals stress variations of different segments’ concrete bottom plates and variations of supports’ reaction forces, demonstrating that the majority of the girder may suffer worse inner force state during construction, compared to the finished state.

Magnetorheological elastomers (MREs), a smart composite, exhibit dual characteristics of both MR materials and particle reinforced composites, i.e., the viscoelasticity of MREs depends on external magnetic field as well as strain amplitude and excitation frequency. In this article, the principle of a frequency-, amplitude-, and magneto-dependent linear dynamic viscoelastic model for isotropic MREs is proposed and investigated. The viscoelasticity of MREs is divided into frequency- and amplitude-dependent mechanical viscoelasticity and frequency-, amplitude-, and magneto-dependent magnetic viscoelasticity. Based on the microstructures of ferrous particles and matrix, the relationships between mechanical shear modulus corresponding to the mechanical viscoelasticity and strain amplitude and excitation frequency are obtained. The relationships between magnetic shear modulus corresponding to the magnetic viscoelasticity with strain amplitude, excitation frequency, and further external magnetic field are derived using the magneto-elastic theory. The influence of magnetic saturation on the MR effect is also considered. The dynamic characteristics of a fabricated isotropic MRE sample under different strain amplitudes, excitation frequencies and external magnetic fields are tested. The parameters of the proposed model are identified with the experimental data and the theoretical expressions of shear storage modulus and shear loss modulus of the MRE sample are obtained. In the light of the theoretical expressions, the loss factors of the MRE sample under different loading conditions are analyzed and compared with the test results to evaluate the effectiveness of the proposed model.

This paper analyzes, for the final disposal of high-level waste (HLW), the possibility of a repository sited below the fresh/saline groundwater interface within islet rock formations. Because of their relatively stable tectonics, the offshore islets of some countries (such as those of Taiwan) are worthy of being considered as potential repository sites. Before the emplacement of radwastes in such a repository, however, the mass exchange across the fresh/saline groundwater interface must be limited and the horizontal movement of advective saline ground-water must be extremely low. Theoretical equations for the location and shape of the interface are derived. When radwastes are buried in rock formations, the temperature effect of the decay heat could cause buoyant convection flow of saline groundwater upward across the groundwater interface. This could carry released radionuclides across the groundwater interface to upper formation layers where fresh groundwater flows. The radionuclides could then be carried by the fresh groundwater to the sea. Although basic HLW repository designs should eliminate the significance of this temperature effect, it is incorporated into this preliminary analysis for the purpose of conservative estimations.

To analytically predict the transport of radionuclides in porous media, it is necessary to develop a complete mathematical model. This means that the mechanisms must be described and the governing equations derived, along with their general solutions for the transport processes. The four major mechanisms---advection, dispersion, adsorption-desorption and ion exchange, and degradation---are physically described and mathematically modeled. Based on the classic principle of mass conservation in a control volume, the governing equation for the transport of radionuclides in porous media is derived, which may be called the advection-dispersion equation. Some general solutions of the governing equation are obtained by using constant dispersion coefficients. In addition, some ambiguities of the advective-dispersion equation are solved, and this equation is extended to fractured media.

The machining of complex curved surface is a highly complex process. Cutting load and the various changes of tool spindle vector are the important causes which restrict the machining precision of complex curved surface and the efficiency of machining. This paper presents an analysis method of machining techniques about complex curved surface based on the advanced analysis theory, and constitutes the relationship among cutting tools, machining parameters and cutting parameters through analyzing the affect factors of the cutting force. Optimize the machining techniques according to the results. Finally using the field process validated that the method is efficacious.