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In this paper, a novel modification method of polypropylene (PP) films is proposed in the field of metallized film capacitors for converter valves. An organic crystallization accelerator with good dispersion improves the micromorphology of PP films. The doping content of the organic crystallization accelerator is optimized based on breakdown experiments under DC voltage. The DC breakdown strength is 584.8 kV/mm, an increase of 19.6%, compared with that of the original film. Under DC, DC superimposed harmonics, and DC superimposed pulse voltages, the modified PP film has successfully withstood the tests, showing stable advantages in breakdown properties without increasing the conduction loss. Trap analysis and theoretical modeling were performed to clarify the mechanism of improving electrical performances based on crystallization control. The entanglement layer introduced by the organic crystallization accelerator helps to expand the crystal area, resulting in deep trap sites and limitation of carrier migration. This research can provide a reference for the PP performance optimization for metallized film capacitors of converter valves.

In this work, polypropylene (PP) film samples doped with an organic phosphorus nucleating agent under three cooling processes are examined for the effects of regulating the crystallization. The conductivity and DC breakdown strength of the film samples were tested at 25, 55 and 85 °C. The average breakdown strength with 0.01 wt% nucleating agent increased by approximately 25% compared to un-nucleating samples and the DC conductivity decreased slightly. For the three cooling methods in these tests, the slow process increased the crystallinity of the film samples and stabilized the electrical properties of the PP samples. It is concluded that improving the insulation performance through crystallization control is feasible, and this method shows great potential for the modification of PP films.

Topology Optimization (TO) is a powerful numerical technique to determine the optimal material layout in a design domain, which has accepted considerable developments in recent years. The classic Finite Element Method (FEM) is applied to compute the unknown structural responses in TO. However, several numerical deficiencies of the FEM significantly influence the effectiveness and efficiency of TO. In order to eliminate the negative influence of the FEM on TO, IsoGeometric Analysis (IGA) has become a promising alternative due to its unique feature that the Computer-Aided Design (CAD) model and Computer-Aided Engineering (CAE) model can be unified into a same mathematical model. In the paper, the main intention is to provide a comprehensive overview for the developments of Isogeometric Topology Optimization (ITO) in methods and applications. Finally, some prospects for the developments of ITO in the future are also presented.

Li3Mg2(Nb1-xWx)O6+x/2 (0 ≤ x ≤ 0.08) ceramics were synthesized by the solid-state reaction route. The effects of W6+ substitution on the phase composition, microstructure and microwave dielectric properties of Li3Mg2NbO6 ceramics were investigated systematically. The XRD results showed that all the samples formed a pure solid solution in the whole doping range. The SEM iamges and relative density revealed the dense structure of Li3Mg2(Nb1-xWx)O6+x/2 ceramics. The relationship between the crystal structure and dielectric properties of Li3Mg2(Nb1-xWx)O6+x/2 ceramics was researched through polarizability, average bond valence, and bond energy. The substitution of W6+ for Nb5+ in Li3Mg2(Nb1-xWx)O6+x/2 ceramics significantly promoted the Q × f values. In addition, the increase of W6+ content improved the thermal stability of the Li3Mg2(Nb1-xWx)O6+x/2 ceramics. The Li3Mg2(Nb0.94W0.06)O6.03 ceramics sintered at 1175 °C for 6h possessed excellent properties: er ~ 15.82, Q × f ~ 124,187 GHz, τf ~ −18.28 ppm/°C.

This paper attempts to reveal the dielectric properties, breakdown properties, surface charge decay, and conductivity properties of copper-calcium titanate (CaCu 3 Ti 4 Oi 2 , abbreviated as CCTO)/EPDM composites. The CCTO/EPDM composites were prepared using high purity oxides of CuO, CaCO 3 and TiO 2 and mechanical blending with EPDM. The experiments have demonstrated that the addition of CCTO increases the dielectric constant in accordance with the internal barrier capacitance model and the Clausius-Mossotti theory. The breakdown field intensity increased to 112 kV/mm with 10 wt% CCTO but then decreased with increasing CCTO. A small amount of CCTO was noticed to accelerate the dissipation of surface charge. In addition, a field-dependent conductivity became evident at a high CCTO content.

A series of novel Li3+xMg2Nb1-xTixO6 (0.02 ≤ x ≤ 0.08) ceramics with excellent microwave dielectric properties and relatively low sintering temperatures were synthesized via the solid-phase method. The correlations between sintering characteristics and microwave dielectric properties of the novel system were analyzed in detail. By (Li+/Ti4+) ions co-doped Li3Mg2NbO6 ceramics, all compounds possessed a single phase with orthorhombic structure, pertaining to the space group Fddd (70). The change regulation of dielectric constant and Q*f values was similar to density, which ascended to the maximum value first and then declined as the sintering temperature increased. Furthermore, the τf values constantly shifted to 0 ppm/°C with the content of complex ions (Li+/Ti4+) increasing. The best properties of Li3.06Mg2Nb0.94Ti0.06O6 ceramics sintered at 1025 °C were er = 14.34, Q*f = 154,113 GHz, and τf = −2.17 ppm/°C.

This paper proposes a new multiscale topology optimization method for the concurrent design of multiphase composite structures under a certain range of excitation frequencies. Distinguished from the existed studies, a general concurrent design formulation for the dynamic composite structures with more than two material phases is developed. The macrostructureand its microstructures with multiple material phases are optimized simultaneously. The integral of the dynamic compliances over an interval of frequencies is formulated as the optimization objective, so as to minimize the frequency response within the concerned excitation range. The effective properties of the multiphase microstructures are evaluated by using the numerical homogenization method, which actually serves as a link to bridge the macro and micro finite element analyses. Furthermore, to describe the boundaries of multiple material phases for the microstructure, a parametric color level set method (PCLSM) is developed by using an efficient interpolation scheme. In this way, L level set functions can represent at most 2 L material phases without any overlaps. Moreover, these “color” level sets are updated by directly using the well-established gradient-based algorithm, which can greatly facilitate the proposed method to solve the multi-material optimizations with multiple design constraints. Several 2D and 3D numerical examples are used to demonstrate the effectiveness of the proposed method in the concurrent design of the dynamic composite structures under the excitation frequency ranges.

A one-pot novel strategy is described for the construction of various oxazolo[4,5-c]quinoline derivatives starting from the isocyano(triphenylphosphoranylidene)acetates, aldehydes, amines, and 2-azidobenzoic acids. The reactions generated the target products directly in moderate to good yields via a sequential Ugi/Wittig/aza-Wittig cyclization process. The salient features of the method are that all three groups of the multifunctional isocyanides were involved in the reaction with broad substituent scopes and mild reaction conditions, making the protocol a useful contribution to the synthesis of oxazolo[4,5-c]quinoline heterocycles.

MgZrNb2−x(Sn1/2W1/2)xO8 (0 ≤ x ≤ 0.15) dielectric ceramics were synthesized through solid state reaction route. SnO2, WO3 and Nb2O5 were pre-calcined to promote the substitution element to fully enter the Nb-site when reacting with MgO and ZrO2. The formation of solid solutions with monoclinic wolframite structure were confirmed. Rietveld refinement and P–V–L theory were used as intrinsic factors of analyzing the changes in microwave dielectric properties. With the increase of (Sn1/2W1/2)5+ substitution amount, er of highly densified MgZrNb2−x(Sn1/2W1/2)xO8 ceramic decreased slowly, which was mainly ascribed to low bond iconicity. The optimal substitution of isovalent composite ions enhances the total lattice energy, leading to an increase in Q × f value. The increase of τf was closely correlated with the decrease of the total bond energy. When x = 0.06, the optimal dielectric properties, er= 24.61, Q × f = 93346.3 GHz, τf= − 48.46 ppm/°C, were successfully obtained for the MgZrNb2−x(Sn1/2W1/2)xO8 specimens sintered at 1300 °C.

Polymeric insulated cable with high ampacity and good thermal performance is the core of the new fast charging technology for electric vehicles (EVs). Advanced materials with both good thermal and electrical properties to improve the performance of EVs charging cable are proposed in this paper. Two sample cables were manufactured with ethylene-propylene-diene (EPDM) insulation and a chlorosulfonated polyethylene rubber (CSM) sheath. Both the insulation and sheathing materials were modified by hybrid boron nitride (BN) to improve the thermal conductivity (TC). The test results show that the modified EPDM insulation has good electrical and mechanical properties. For the temperature characteristics of these two cables, the adoption of high TC EPDM insulation and CSM sheath can improve the heat dissipation capability and the temperature distribution in the cable. In addition, the theoretical ampacity of the cable was calculated showing a significant improvement. The employment of high TC insulation and sheath appears to be of great benefit to the reduction of temperature and increase in ampacity of EV charging cables.

An energy-storage system comprised of lithium-ion battery modules is considered to be a core component of new energy vehicles, as it provides the main power source for the transmission system. However, manufacturing defects in battery modules lead to variations in performance among the cells used in series or parallel configuration. This variation results in incomplete charge and discharge of batteries and non-uniform temperature distribution, which further lead to reduction of cycle life and battery capacity over time. To solve this problem, this work uses experimental and numerical methods to conduct a comprehensive investigation on the clustering of battery cells with similar performance in order to produce a battery module with improved electrochemical performance. Experiments were first performed by dismantling battery modules for the measurement of performance parameters. The k-means clustering and support vector clustering (SVC) algorithms were then employed to produce battery modules composed of 12 cells each. Experimental verification of the results obtained from the clustering analysis was performed by measuring the temperature rise in the cells over a certain period, while air cooling was provided. It was found that the SVC-clustered battery module in Category 3 exhibited the best performance, with a maximum observed temperature of 32 °C. By contrast, the maximum observed temperatures of the other battery modules were higher, at 40 °C for Category 1 (manufacturer), 36 °C for Category 2 (manufacturer), and 35 °C for Category 4 (k-means-clustered battery module). Keywords: Clustering algorithm, Battery module, Equalization, Electric vehicle

Dependence of microwave dielectric properties on the crystal structure of Zn1−xNixZrNb2O8 was investigated as a function of NiO content (x = 0, 0.02, 0.04, 0.06, 0.08). Pure single phase with monoclinic wolframite structure was obtained through solid-state reacti. The unit-cell volume of the specimens decreased with NiO content because of the smaller ionic radius of Ni2+ than Zn2+. Dielectric constant (K) of the sintered specimen was affected by bond-ionicity. Quality factor (Q × f0) was analyzed depending on the lattice-energy. With the increase of Ni2+, temperature coefficient of resonant frequency (τf) of specimens increased due to the increase of B-site bond energy. The sample of Zn1−xNixZrNb2O8 (x = 0.08) sintered at 1250°C for 4 h showed excellent microwave dielectric properties, er of 25.72, Q × f0 value of 73224 GHz, and τf of − 39.14 ppm/°C.

The crystal structure and microwave dielectric properties of Li2Mg3Ti1−xSnxO6 (0.02 ≤ x ≤ 0.08) ceramics were investigated. The crystal structure and unit cell volume of samples were obtained by Rietveld refinement. The er value had a similar trend with the pore corrected theoretical dielectric constant ecorr, which was affected by the polarizability value and molar volume. The variations of Q × f values were related to the different lattice vibrations. And the change of τƒ had a close relationship with the dielectric constant. Above all, the superior dielectric properties of ɛr ~ 13.16, Q × f~168,800 GHz, τƒ ~ − 29.8 ppm/ °C were obtained for Li2Mg3Ti0.94Sn0.06O6 ceramics sintered at 1350 °C. Furthermore, LiF was added to Li2Mg3Ti0.94Sn0.06O6 ceramics to lower the sintering temperature. The sintering behavior and dielectric properties of Li2Mg3Ti0.94Sn0.06O6-ywt%LiF (2 ≤ y ≤ 5) ceramics were also analyzed. Finally, the excellent dielectric properties of ɛr ~ 15.58, Q × f~142,210 GHz and τƒ ~ − 34.5 ppm/ °C for Li2Mg3Ti0.94Sn0.06O6-3wt%LiF ceramics were obtained sintered at 900 °C, which could be applied to the LTCC technology.

This paper proposes a method combining projection-outline-based active learning strategy with Kriging metamodel for reliability analysis of structures with mixed random and convex variables. In this method, it is determined that the approximation accuracy of projection outlines on the limit-state surface is crucial for estimation of failure probability instead of the whole limit-state surface. To efficiently improve the approximation accuracy of projection outlines, a new projection-outline-based active learning strategy is developed to sequentially obtain update points located around the projection outlines. Taking into account the influence of metamodel uncertainty on the estimation of failure probability, a quantification function of metamodel uncertainty is developed and introduced in the stopping condition of Kriging metamodel update. Finally, Monte Carlo simulation is employed to calculate the failure probability based on the refined Kriging metamodel. Four examples including the Burro Creek Bridge and a piezoelectric energy harvester are tested to validate the performance of the proposed method. Results indicate that the proposed method is accurate and efficient for reliability analysis of structures with mixed random and convex variables.

The elevated temperature in operating capacitors speeds up the transportation of charges and causes the flashover to occur easily. Direct fluorination was used to modify the polypropylene film applied as capacitor dielectric, and behaviors of surface charging and flashover voltage at different temperatures were investigated. The surface morphology, functional groups and elemental composition of polypropylene film before and after modification treatment were characterized by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive x-ray analysis (EDAX), respectively. The surface charging behaviors were analyzed by the surface potential decay (SPD) method at temperature varying from 293 to 353 K. The flashover voltage was analyzed by the view of surface charge and trap characteristics. A thin layer of fluorination which changed the surface state of polypropylene film was formed, which can effectively inhibit the surface charge injection and accumulation at different temperatures. Shallow traps were introduced by the surface molecular structure modification, which was confirmed by the simulation of three-dimensional (3D) electrostatic potential and density of states (DOS). The modification of surface molecular structure, which suppresses the accumulation of surface charge leading to the inhibited distortion of electric field, effectively increased the flashover voltage at different temperatures.

CaCu3+xTi4O12+x (x = 0, 0.1, 0.2, 0.4, 0.8) thin films with obvious non-Ohmic behaviors were prepared through magnetron sputtering method. The second phase of CuO and TiO2 were detected in all Cu-rich ceramic targets, and CuO was detected in thin film sample when x = 0.8 which contributed to the increased grain size. The nonlinear I–V behaviors were explained by Schottky emission and Poole–Frenkel electrons transportation mechanism. The nonlinear coefficient increased with x, reached the maximum when x = 0.4 and then decreased, which is in accordance with the changing trend of trap barrier height, meaning that Poole–Frenkel model can describe the non-Ohmic behaviors of Cu non-stoichiometric samples better than Schottky emission model.

The Li2Mg3TiO6 ceramics doped with ZnO B2O3 SiO2 (ZBS)/Li2O B2O3 SiO2 (ZBS) glass were synthesized through the conventional solid-state reaction route. The phase compositions, microstructures, sintering characteristics and microwave dielectric properties of Li2Mg3TiO6-xwt%ZBS and Li2Mg3TiO6-xwt%LBS (0 ≤ x ≤ 8) were investigated. With the increase of low-melting ZBS/LBS glass, the densification of Li2Mg3TiO6 ceramics was improved significantly through the mechanism of liquid phase sintering. The addition of ZBS/LBS glass could effectively lower the sintering temperature from 1350 °C to 1025 °C/1050 °C and had slightly influences on microwave dielectric properties of Li2Mg3TiO6 ceramics. The dielectric constant ɛr and Q×f values correlated with bulk density strongly. The temperature coefficient of resonant frequency (τf) was reduced by adding ZBS/LBS glass, due to the formation of the second phase MgSiO4. Compared with Li2Mg3TiO6-4wt%LBS sintered at 1050 °C, Li2Mg3TiO6 ceramics with 4 wt% ZBS glass sintered at 1025 °C had higher densification and more uniform grain morphology, which displayed excellent microwave dielectric properties of ɛr∼13.35, Q×f∼138,800 GHz and τƒ∼-31.84 ppm/°C.

The dense MgZr(Nb1−xSbx)2O8 ceramics were synthesized through standard solid state reaction route. All samples were identified as the pure phase with monoclinic wolframite structure and P2/c space group. SEM was carried out to study the effect of surface morphology on dielectric properties. Rietveld refinement was utilized to observe the impact of equivalent substitution (Sb5+) at the Nb-site on the microstructure of crystals. The phenomenon of non-monotonic changing in quality factor (Q × f) and monotonic increase in dielectric constant (er) was explained by bond ionicity and lattice energy based on the P-V-L theory. In addition, the deterioration of temperature coefficient of resonant frequency (τf) was closely related to the reduction of bond energy. Finally, the optimum dielectric properties of MgZr(Nb0.92Sb0.08)2O8 sample sintered at 1320 °C for 6 h were obtained: er = 25.69, Q × f = 83505.2 GHz, τf = −58.74 ppm/°C.

In this paper, a single-opening microring resonator (SOMRR) is proposed for simultaneous measurement of refractive index (RI) and pressure. The notch angle lifts the degeneracy of clockwise and counter-clockwise WGMs to excite the mode splitting, forming the symmetric and the asymmetric standing wave modes (SWMs) in the SOMRR. Due to the different electromagnetic field energy distribution of the two SWMs, the symmetric SWM and the asymmetric SWM show different sensitivities toward the change of ambient RI and the pressure exerted on the resonator. Through the three-dimensional FDTD simulations of the two SWMs under different external environments and loads, we obtain a RI sensitivity of 77.07 nm/RIU, a high pressure sensitivity of 5.01 pm/kPa for the symmetric SWM and a RI sensitivity of 69.54 nm/RIU, a high pressure sensitivity of 5.72 pm/kPa for the asymmetric SWM. Moreover, by solving the inverse matrix of the sensitivity matrix, the resonance wavelength shifts respectively caused by the change of RI and pressure can be distinguished. For the biosensing application based on the flexible photonic device, the effect of strain-optical coupling can be eliminated by using this method. It advances the accuracy of detection results and provides a novel route to achieve its application for biosensing in the real world.

s The La(Nb1-xTax)O4 (x = 0–0.10) ceramics were prepared by the conventional solid-state reaction method. For the first time, the correlations of bond ionicity, lattice energy, bond energy and the microwave dielectric properties of La(Nb1-xTax)O4(x = 0–0.10) ceramics were investigated. X-ray diffraction patterns of La(Nb1-xTax)O4 (x = 0–0.10) specimens showed that the samples presented single monoclinic fergusonite structure of LaNbO4, and no second phases could be detected. Moreover, the Rietveld refinement method was used to investigate the crystal structure of the ceramics. The variation trend of dielectric constant (er) was closely related to that of bond ionicity. When there is no distortion of lattice for ceramics, the quality factor (Q × f) values and τf values were correlated with lattice energy and bond energy, respectively. With x = 0.08, optimal microwave dielectric properties could be obtained for La(Nb1-xTax)O4 (x = 0–0.10) ceramics: er = 19.23, Q × f = 65653 GHz and τf = 3.03 ppm/°C.

Shell-infill structures are widely used in additive manufacturing (AM) to retain the external appearance and reduce the printing costs. However, shell-infill structures are generally designed by a mono-scale topology optimization method. In this case, these shell-infill structures are not optimal designs due to their incompatible shell and infill layouts. In order to obtain the optimized shell and infill simultaneously, this paper presents a multiscale level set topology optimization method for designing shell-infill structures. In macroscale optimization, two distinct level sets of a single level set function (LSF) are used to represent the interface of the shell and the infill, respectively. The thickness of the shell is assumed to be uniform, which is guaranteed by a level set reinitialization scheme. In microscale optimization, the pattern of the microstructure is optimized to achieve the optimal macro structural performance. The numerical homogenization method is applied to evaluate the effective elasticity matrix of the microstructural infill. The shell-coated macro structure and the micro infill are optimized concurrently to achieve the optimal shell-infill design with prescribed volume fractions. Both 2D and 3D examples are investigated to demonstrate the effectiveness of the presented method.

Magnesium melilite (Ca2MgSi2O7) ceramic with tetragonal crystal structure was prepared through the conventional solid-state method. Crystal structure and complex chemical bond theory were used to analyze the microwave properties of Ca2MgSi2O7 ceramics and the correlations between the bond ionicity, lattice energy, bond energy and relative dielectric constant (er), quality factor (Q × f0), temperature coefficient of resonant frequency (τf) were discussed in depth. Optimum microwave dielectric properties were obtained when sintered at 1300°C for 4 h: er= 9.86, the dielectric loss (tanδ) was 1.24 × 10−4 (at 1 MHz), Q × f0= 8016 GHz (resonant frequency f0 = 7.90 GHz), τf= − 42 ppm/°C.

The SrCuSi4O10-x wt% LiF (x = 0.5, 1.0, 1.5, 2.0) ceramics were prepared by the conventional solid-state route. The effects of LiF on the sintering behavior, microstructure, phase evolution and dielectric properties of the SrCuSi4O10 ceramics were systematically investigated. And the sintering temperature of SrCuSi4O10 ceramics has been reduced to 900 °C from 1100 °C with a certain amount of LiF. The SrCuSi4O10 ceramics with 1.0 wt% LiF addition sintered at 900 °C for 6 h exhibited excellent dielectric properties of er∼5.88, tanδ∼1.6 × 10−3, τe∼119.90 ppm/°C. However, the relatively large positive τe was unfavorable to practical applications. Hence, the TiO2 that owned a considerable negative τe was introduced to obtain a desired τe value. The addition of 21 wt% TiO2 effectively improved the temperature stability of ceramics and τe was adjusted to near zero. The prepared SrCuSi4O10-1.0 wt% LiF-21 wt% TiO2 ceramics sintered at 900 °C for 6 h showed fairly good dielectric properties of er∼6.73, tanδ∼3.7 × 10−3, τe∼1.80 ppm/°C.

Electric field optimization is a critical technique to ensure the compact structure and reliable operation for AC gas insulated power apparatus. To obtain a more uniform electric field distribution, this paper proposes the concept of the d-SFGM insulator, i.e., applying the surface functionally graded material (SFGM) with a designed thickness (d) distribution of high permittivity along the insulator surface. The magnetron sputtering technique was used to fabricate the d-uniform insulator and the d-SFGM insulator by depositing BaTiO3 layers. The theoretical analysis indicates that the electric field distribution is optimized using the d-SFGM insulator, followed by the d-uniform insulator. The finite element simulations were employed to investigate the electric field distributions and dielectric losses of different insulators. The results show that for the case of the d-uniform insulator, a higher permittivity or larger thickness of the sputtering layer results in a more uniform electric field distribution. With the application of the d-SFGM insulator, the maximum electric field strength and dielectric loss are both significantly reduced compared to the d-uniform insulator. Finally, experimental tests were conducted to further verify the feasibility of SFGM. The AC flashover voltage of the d-SFGM insulator is much higher than those of the conventional insulator and the d-uniform insulators. Therefore, the d-SFGM insulator has great potential for improving the reliability of the AC gas insulated power apparatus.

Li2(Ni1-xMgx)3TiO6 (0 ≤ x ≤ 1) ceramics were synthesized via conventional solid-state reaction. The changes of phase compositions, crystalline structures, sintering behaviors and microwave dielectric properties were investigated firstly as the Li2Ni3TiO6 ceramics transformed into Li2Mg3TiO6 ceramics. With the addition of Mg2+ ions, the quality factor (Q × f) was improved greatly from 18,159 GHz to 152,189 GHz due to the expansion of cell volume. The dielectric constant er had a similar trend with the electronic oxide polarizabilities, which was determined by the energy gap, the cation polarizability, and the molar volume. In addition, the octahedral distortion and bond energy were calculated and the temperature coefficient of resonant frequency (τf) correlated with the bond energy of Ni/Mg-O (ENi/Mg-O) primarily.

This paper presents a novel multiscale concurrent topology optimization method for cellular structures with various types of microstructures to obtain a superior structural performance at an affordable computation cost. At macroscale, different microstructures are regarded as different materials in a multi-material topology optimization. An ordered solid isotropic material with penalization (SIMP) interpolation model, which is efficient for solving multi-material topology optimization problems without introducing any new variables, is employed to generate an overall structure layout with predetermined multiple materials. At microscale, each macroscale element is viewed as an individual microstructure. All macroscale elements with the same material are represented by a unique microstructure. A parametric level set method (PLSM) is applied to evolve the shape and topology of the representative microstructures, whose effective properties are evaluated by a numerical homogenization method. The connectivity of adjacent microstructures is guaranteed by a kinematical connective constraint. Using the proposed method, the macrostructural topology as well as the locations and configurations of microstructures can be simultaneously optimized. Numerical examples are provided to test the effectiveness of the proposed method.

Dense Mg(Zr1-xGex)Nb2O8 (x = 0, 0.1, 0.2, 0.3, 0.4) ceramics were successfully synthesized through traditional solid state reaction route. The relations between microstructure and microwave dielectric properties were studied. The formation of single MgZrNb2O8 phase with the monoclinic wolframite structure was verified by XRD patterns. Experimental dielectric constant was found to be closely related to bond polarizability, and theoretical dielectric constant calculated based on P-V-L theory shows the same tendency with the experimental dielectric constant when the substitution amount of Ge4+ changes. The increase in Q×f and |τf| were mainly attributed to the increase in packing fraction and the Nb-site bond valence, respectively. Excellent dielectric properties were obtained for Mg(Zr1-xGex)Nb2O8 (x = 0.2) ceramic sintered at 1300 °C for 4 h: er= 24.26, Q×f= 80,492.8 GHz, τf= -51.95 ppm/°C.

The Ca1-xSrxWO4 (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10) ceramics were fabricated through solid-state reaction, and the relationships among microwave dielectric properties of Ca1-xSrxWO4, bond ionicity, lattice energy and bond energy were systematically investigated for the first time. The patterns of X-ray diffractions of Ca1-xSrxWO4 presented tetragonal scheelite structure and no second phase appeared throughout the entire compositions. Dielectric properties of Ca1-xSrxWO4 were proved to be related to the microstructures: dielectric constant (er) of Ca1-xSrxWO4 was dependent on the bond ionicity; the quality factor (Q×f0) of Ca1-xSrxWO4 was affected by W-site lattice energy when intrinsic loss is dominant; the temperature coefficient of resonant frequency (|τf|) would increase if B-site bond energy decreased. Ca1-xSrxWO4 ceramic showed excellent microwave dielectric properties, er = 9.42, Q×f0 = 79876 GHz and τf = −18.8 ppm/°C when x = 0.08 and sintered at 1100 °C for 4 h.

For a rapid enrichment and separation of minor components from Malus hupehensis, the selection of suitable solvent system is the great challenge for liquid-liquid extraction with a three-phase solvent system and high-speed counter-current chromatography. According to the concept of "like dissolves like," the similarity of the average polarity between solvent system and target compounds was the significant characteristic of liquid-liquid extraction with a three-phase solvent system and high-speed counter-current chromatography separation. The polarity parameter model provides a way to calculate the polarity of unknown compounds. Under the guidance of the polarity, an efficient enrichment and separation approach was established through liquid-liquid extraction and high-speed counter-current chromatography with solvent systems composed of n-hexane-ethyl acetate-acetonitrile-water (5:3:5:7, v/v), n-hexane-ethyl acetate-methanol-water (1:2:1:2, v/v), respectively. Thus, the total content of minor compounds was increased from 2.6% to 17.2%, and two novel compounds (6´´-O-coumaroyl-2´-O-glucopyranosylphloretin and 3´´´-methoxy-6´´-O-feruloy-2´-glucopyranosylphloretin) were obtained. The discovery of the new dihydrochalcones expanded the structural diversity of compounds produced by the genus Malus. The experimental results demonstrated that compound polarity can be described by the polarity parameter model and is an important reference for investigating optimum solvent systems for liquid-liquid extraction with a three-phase solvent system and high-speed counter-current chromatography.

Metallized film capacitors are the core equipment of converter stations and the polypropylene (PP) films act as the main insulation. The microstructure of polypropylene films will be damaged in the long-term operation under DC voltage and eventually leads to insulation failures. In this paper, the PP films were prepared with different contents of nucleating agent. The micromorphology was observed and the crystallization properties were investigated. The breakdown experiments were conducted and the average DC breakdown strength of the PP film with 0.01 wt.% nucleating agent is increased by approximately 25.7% compared with that of the original sample. The conclusion can be drawn that the improvement of the insulation performance through crystallization control is feasible and shows a great potential in practical applications.

Ferroelectric polymer P(VDF-TrFE-CFE) is widely employed as energy storage materials of dielectric capacitors, but the discharge energy density of P(VDF-TrFE-CFE) is limited by the lower breakdown strength, which restricts the further development. The paper proposes a solution by preparing P(VDF-TrFE-CFE) composites based on bilayer structure and nanoparticles. Polyimide (PI) with high breakdown strength is used as the bottom layer, and the BaTiO 3 /Ferroelectric polymer composites BT-P(VDF-TrFE-CFE) with high dielectric constant is used as the top layer, the bilayer composite films PI/BTP(VDF-TrFE-CFE) doped with different content of BaTiO 3 (1 vol.%, 3 vol.%, 5 vol.%) were prepared via coating, heat treatment and quenching. The microstructure and energy storage performance of bilayer films were analyzed, the results show that the discharge energy density of composite film doping with 3 vol.% of BaTiO 3 can be up to 9.8 J/cm3 at 440 kV/mm, which is higher than pure P(VDF-TrFE-CFE) film (7.2 J/cm3). The energy storage efficiency of composite film is 46% at 440 kV/mm, slightly lower than pure P(VDF-TrFE-CFE) film (49% at 337 kV/mm).

As the search continues for useful applications of noisy intermediate scale quantum devices, variational simulations of fermionic systems remain one of the most promising directions. Here, we perform a series of quantum simulations of chemistry the largest of which involved a dozen qubits, 78 two-qubit gates, and 114 one-qubit gates. We model the binding energy of ${\rm H}_6$, ${\rm H}_8$, ${\rm H}_{10}$ and ${\rm H}_{12}$ chains as well as the isomerization of diazene. We also demonstrate error-mitigation strategies based on $N$-representability which dramatically improve the effective fidelity of our experiments. Our parameterized ansatz circuits realize the Givens rotation approach to non-interacting fermion evolution, which we variationally optimize to prepare the Hartree-Fock wavefunction. This ubiquitous algorithmic primitive corresponds to a rotation of the orbital basis and is required by many proposals for correlated simulations of molecules and Hubbard models. Because non-interacting fermion evolutions are classically tractable to simulate, yet still generate highly entangled states over the computational basis, we use these experiments to benchmark the performance of our hardware while establishing a foundation for scaling up more complex correlated quantum simulations of chemistry., updated link to experiment code, new version containing expanded data sets and corrected figure label

This paper focuses on the hybrid reliability analysis with both random and interval variables (HRA-RI). It is determined that a metamodel only accurately approximating the projection outlines on the limit-state surface can precisely estimate the lower and upper bounds of failure probability in HRA-RI. According to this idea, a novel projection outline based active learning (POAL) method is proposed to sequentially update design of experiments (DoE). Then, a HRA-RI method combining POAL and Kriging metamodel (POAL–Kriging) is developed. In this method, Kriging metamodel is refined based on the update samples, which are sequentially chosen using POAL from the vicinity of the projection outlines on the limit-state surface. In the end, the lower and upper bounds of failure probability in HRA-RI are precisely estimated. Compared to the approximation of the whole limit-state surface, the proposed method only approximates the projection outlines on the limit-state surface, and therefore few DoE are needed to build a high quality metamodel. The accuracy, efficiency and robustness of the proposed method for HRA-RI are illustrated by four examples.

Low-permittivity Sr2MgSi2O7 ceramics with tetragonal crystal structure were prepared through the conventional solid-state method. X-ray diffraction patterns and scanning electron microscopy were used to analyze the phase and micromorphology of the specimens sintered at temperature from 1260 to 1320 °C. The bond ionicity, lattice energy and bond energy of Sr2MgSi2O7 ceramics were calculated to investigate the relationships between microwave dielectric properties and microstructures. Optimum microwave dielectric properties were obtained when the sample was sintered at 1280 °C for 4h: er = 6.85, Q × f0 = 22,530 GHz (f = 9.20 GHz), τf = − 32 ppm/°C.

The LiNiPO4 ceramic for the LTCC technology was prepared via the traditional solid-state reaction route and its dielectric properties were investigated for the first time. The best dielectric properties of LiNiPO4 ceramics with a er of 7.18, Q×f value of 27,754 GHz and τf of −67.7 ppm/°C were obtained in samples sintered at 825 °C for 2 h. Rietveld refinement was firstly employed to study the crystal structure and dielectric properties of LiNiPO4 ceramics. Unfortunately, the relatively large negative τf was unfavorable to practical applications. Therefore, we introduced TiO2, which possessed a considerable positive τf, to obtain a desired τf value. The prepared LiNiPO4 ceramics with 15 wt% TiO2 sintered at 900 °C for 2 h exhibited excellent dielectric properties of er∼11.49, Q×f∼10,792 GHz, τf∼−2.8 ppm/°C. The Ag co-fired experiments confirmed the excellent chemical compatibility with LiNiPO4-TiO2 ceramics which might be potential dielectric LTCCs for high frequency applications.

The Li3Mg2(Nb1-xSbx)O6 (0.02 ≤ x ≤ 0.08) ceramics were prepared by partial substitution of Sb5+ on Nb5+ site for the first time. The effects of Sb5+ ion substitution on the microstructures and microwave dielectric properties were discussed in detail. The relationship between structural characteristics and dielectric properties of Li3Mg2(Nb1-xSbx)O6 ceramics was investigated based on the complex chemical bond theory. Synthesized via the solid-state reaction route, Li3Mg2(Nb1-xSbx)O6 ceramics exhibited excellent dielectric properties. With the increase of Sb5+ substitution amount, er increased, Q × f values first went up then fell, and τf shifted for the positive direction. The bond ionicity, lattice energy and bond energy of Li3Mg2(Nb1-xSbx)O6 ceramics were employed to study the crystal structure and dielectric properties. Typically, the best dielectric properties with a er of 15.79, Q × f value of 95,487 GHz and τf of −24.53 ppm/oC were obtained in Li3Mg2(Nb1-xSbx)O6 (x = 0.06) ceramics sintered at 1150 °C for 6 h.

The Li3(Mg1-xCax)2NbO6(0.02 ≤ x ≤ 0.08) ceramics were prepared through a solid-state reaction method. The effects of Ca2+ substitution for Mg2+ on the phase composition, microstructure and microwave dielectric properties of Li3(Mg1-xCax)2NbO6 ceramics were investigated systematically. The XRD results showed that all the samples remained a single Li3Mg2NbO6 phase with orthorhombic structure and Ca2+ ions could result in the expansion of unit cells when sintered at 1060–1220 °C for 6 h. In this study, the change trend of the porosity-corrected permittivity showed that the permittivity of samples was mainly relative to density, not to ionic polarizability. The variation of Q × f values also exhibited a similar trend as that of density. The τf values were in accordance with the porosity-corrected permittivity. Excellent microwave dielectric properties of er ∼16.81, Q × f ∼122,082 GHz, τf ∼ −25.8 ppm/oC were obtained in the x = 0.04 sample when sintered at 1140 °C for 6 h. In addition, various amounts of LiF were used as sintering additive to reduce the sintering temperature in Li3(Mg0.96Ca0.04)2NbO6 ceramics. The best microwave dielectric properties of er ∼15.85, Q × f ∼98,012 GHz, τf ∼ −28.6 ppm/oC appeared to be Li3(Mg0.96Ca0.04)2NbO6 ceramics with 6 wt% LiF sintered at 900 °C. Besides, this composition was compatible with Ag electrode, demonstrating that it could be a promising candidate material for LTCC applications.

Breast cancer is a severe threat to the health and lives of women due to its difficult early diagnosis and the unsatisfactory therapeutic efficacy of breast cancer treatments. The development of theranostic strategies to combat breast cancer with high accuracy and effectiveness is therefore urgently needed. In this study, we describe a near-infrared (NIR) light-controllable, targeted and biocompatible drug delivery nanoplatform (PFH-PTX@PLGA/SPIO-Her) for photoacoustic (PA)/ultrasound (US) bimodal imaging-guided photothermal (PTT)/chemo synergistic cancer therapy of breast cancer. Carboxyl-modified PEGylated poly (lactic-co-glycolic acid) (PLGA-PEG-COOH) constituted the skeleton of the nanoplatform. Especially, the antibody Herceptin was modified onto the surface of nanoplatform for active HER2-targing to facilitate the tumor accumulation of the nanoplatform. The encapsulated superparamagnetic iron oxide (SPIO) nanoparticles could be employed as an excellent PA imaging agent to guide tumor therapy. When exposed to NIR light, the SPIO also could transform NIR light into thermal energy for photothermal ablation of tumor. The NIR-induced thermal effect subsequently triggered the optical droplet vaporization (ODV) of perfluorohexane (PFH) to generate PFH gas bubbles, which not only achieved the US imaging enhancement, but also contributed to the release of loaded paclitaxel (PTX) from the nanoplatform for significantly improving PTT therapeutic efficacy. Our results demonstrated that the targeted tumor accumulation, accurate real-time bimodal imaging, and the abundant drug release at the tumor site were all closely associated with the PTT therapeutic efficacy. Therefore, the theranostic nanoplatform is a very promising strategy for targeted imaging-guided photothermal/chemo synergistic tumor therapy with high therapeutic efficacy and minimized side effects. STATEMENT OF SIGNIFICANCE: Breast cancer is the most frequent cancer in women. Herein, we successfully developed a light-controllable and HER2 targeted theranostic nanoparticels (PFH-PTX@PLGA/SPIO-Her) as a specific drug delivery nanoplatform to overcome the low accuracy of tumor detection and the low specificity of traditional chemo-therapeutic protocols. The study demonstrated that PFH-PTX@PLGA/SPIO-Her could actively target to breast cancer cells with positive HER2 expression. The biocompatible PFH-PTX@PLGA/SPIO-Her nanoparticles as both photoacoustic/ultrasound bimodal imaging agents, photothermal-conversion nanomaterials (photothermal hyperthermia) and controllable drug delivery nanoagents (optical droplet vaporization) have completely eradicated the tumor without severe side effects. The theranostic strategy not only integrates strengthens of traditional imaging or therapeutic modalities, but also paves a new way for the efficient cancer treatment by taking the advantage of quickly-developing nanomedicine.

MgZr0.85Sn0.15Nb2O8 ceramics with wolframite structure were synthesized through traditional solid-state reaction process. X-ray diffraction and scanning electron microscopy were used to analyze the phase and surface morphology. Bond ionicity, lattice energy and bond energy were calculated separately to investigate the correlations with microwave dielectric properties. Typically, optimal microwave dielectric properties were obtained at 1260 °C: er = 24.91, Q × f = 94014 GHz, τf=− 43.93 ppm/oC.

0.9BaTiO3–0.1(Bi0.5Na0.5)TiO3–x mol% NiNb2O6 (x = 0, 0.5, 1.0, 1.5, 2.0, 2.5) ceramics were prepared through traditional solid-state reaction method. The effects of NiNb2O6 doping on the dielectric properties and the microstructure of ceramics were investigated systematically. The results showed that the grain size of the ceramics decreased with the increase of NiNb2O6 doping amount. Ba11(Ni,Ti)28O66+x and Nb2O5 were detected in the X-ray diffractions patterns. The Curie point Tc increased slightly with the increase of NiNb2O6 doping amount. It was interesting to find that the dielectric constant at low temperature of the ceramics first increased and then decreased with the increase of NiNb2O6 concentration. Dielectric temperature stability of 0.9BaTiO3–0.1(Bi0.5Na0.5)TiO3 ceramics greatly depended on NiNb2O6 content. The optimum dielectric properties meeting the X9R specification were obtained in the composition of 0.9BaTiO3–0.1(Bi0.5Na0.5)TiO3 with 1.5 mol% NiNb2O6 sintered at 1200 °C, er = 1652 and tanδ = 1.8% at room temperature.

LaNiO3 thin films with different La/Ni ratios were deposited on Si substrates by sol-gel process. The electrical resistivities of LaNixO3+δ films with different La/Ni ratios were measured by four-probe method. LaNi0.95O3+δ thin film has the lowest resistivity. First-principle calculations show that LaNi0.95O3+δ has the largest Ni–O–Ni bond angle and the shortest Ni–O bond length, which means LaNi0.95O3+δ has the strongest metallic property, hence, the electrical resistivity is the lowest. Au/PZT (PbZr0.52Ti0.48O3)/LaNixO3+δ and Au/PZT/Pt ferroelectric capacitors were fabricated to evaluate LaNixO3+δ as a bottom electrode. It is shown that fatigue properties of PZT films can be significantly improved by using LaNixO3+δ instead of Pt as the bottom electrode. The I-V test results of PZT films show that LaNi0.95O3+δ as bottom electrode can reduce the threshold voltages of PZT films, suggesting that La/Ni ratio in LaNixO3+δ has a large influence on the film properties.

Dense Mg1-xCoxZrNb2O8 (0 ≤ x ≤ 0.10) ceramics samples were prepared through solid-state reaction method. The influence of Co2+ substitution on phase composition, crystal structure and microwave dielectric properties were investigated systematically. Dielectric polarizability, packing fraction and bond valence were calculated respectively to investigate the correction with dielectric constant, quality factor and temperature coefficient of resonant frequency. Especially, optimal microwave dielectric properties with er = 25.18, Q × f = 70709 GHz, τf = −46.09 ppm/°C were obtained for the sample of Mg0.98Co0.02ZrNb2O8 sintered at 1260 °C for 4 h.

LaNbO4 ceramics with single monoclinic fergusonite structure were prepared by the conventional solid-state reaction method at the sintering temperature range of 1275–1375 °C. The correlations of bond ionicity, lattice energy, bond energy and the microwave dielectric properties were investigated. The bond ionicity, lattice energy, and bond energy were calculated based on the complex bond theory to analyze the variation trend of dielectric constant (er), the Q × f0 value and the temperature coefficient of resonant frequency (τf), respectively. LaNbO4 ceramics sintered at 1350 °C for 4 h possessed excellent microwave dielectric properties: er = 21, Q × f0 = 55600 GHz and τf = 8 ppm/°C.

In this paper, an improved two-stage framework is presented to handle the evidence-based design optimization (EBDO) problem under epistemic uncertainty. The improvements include two aspects: (1) in the first stage, the equal areas method is employed to transform evidence variables into random variables, which avoids the assumption that unknown evidence variables and parameters obey the normal distribution. Then, a reliability-based design optimization (RBDO) problem with random variables is defined and solved by the sequential optimization and reliability assessment (SORA) method; (2) in the second stage, an improved algorithm is presented, which can calculate the plausibility of constraint violation more efficiently by continuously recording the minimum and maximum values of limit-state functions. The computational accuracy and efficiency of the improved framework are tested by numerical and engineering examples.

In this paper, the crystal orientations of Pb(Zr0.52Ti0.48)O3 (PZT) thin films prepared by sol–gel method were investigated by using various initial annealing temperature in the modified annealing process. The films were put directly into the muffle furnace when the temperature reached at 300–500 °C, it’s clear that this modified annealing process made the PZT films presented better (111)-orientation. A PtxPb intermetallic metastable phase was observed by X-ray diffraction, which is considered to be connected with the promotion of the (111) preferred orientation. The PZT thin film with 400 °C initial annealing temperature has the maximum (111) diffraction intensity, remanent polarization and dielectric constant.

CaCu3Ti4O12-xMgTiO3 (x = 0, 0.05, 0.1 and 0.2) thin films were prepared through magnetron sputtering method and sintered at 850 °C for 1 h. Second phase of CuO and TiO2 were detected in MgTiO3 doped ceramic targets and CaTiO3 phase was observed when x = 0.2. SEM results showed that grain size increased with MgTiO3 doping, which is corresponding to the decrease of threshold voltage. Remarkable non-Ohmic behaviors of all samples were observed at different temperatures. Nonlinear coefficient increased from 2.803 (x = 0) to 3.799 (x = 0.2) and Schottky barrier height increased firstly then decreased as MgTiO3 doping. Double Schottky barrier model was used to explain the non-Ohmic characteristic of CCTO thin films.

High-Q Li2MgxTiO3+x (2.2 ≤ x ≤ 4) microwave dielectric ceramics were fabricated by using a conventional solid-state reaction method followed by laminated sintering technique. All samples showed clear and smooth grains through this sintering method. The XRD patterns indicated that Li2MgxTiO3+x (2.2 ≤ x ≤ 4) ceramics displayed MgO-like cubic phase with ordered rock salt structure. The dielectric constant decreased monotonically because the molar volume expanded and molecular polarizability decreased when x values increased. The Q × f values of Li2MgxTiO3+x (2.2 ≤ x ≤ 4) ceramics were dependent significantly on both average grain sizes and packing fraction. The Li2Mg3.6TiO6.6 ceramics sintered at 1375 °C had excellent microwave dielectric properties of er ∼ 12.7, Q × f ∼ 169,000 GHz, τf ∼ −32.8 ppm/°C.

Pure phase MgZr 1−x Sn x Nb 2 O 8 (x = 0, 0.1, 0.15, 0.2, 0.25 and 0.3) ceramics were first synthesized through conventional solid-state method. The theoretical dielectric polarizabilities, packing fractions and bond valences of MgZr 1−x Sn x Nb 2 O 8 ceramics were calculated in order to investigate the correlation between the crystal structure and microwave dielectric properties. A small amount of Sn 4+ substituted for Zr 4+ effectively improved the quality factor, but excessive substitution is not conducive to the improvement of Q × f value. Excellent microwave dielectric properties of e r = 24.91, Q × f = 94,014.2 GHz, τ f = −43.93 ppm/°C were obtained for the MgZr 1−x Sn x Nb 2 O 8 ceramics with x = 0.15 sintered at 1260 °C.

In this paper, LaNbO 4 ceramics with BaCu(B 2 O 5 ) additives were prepared via the conventional solid state reaction method. The effects of BaCu(B 2 O 5 ) on sintering behavior, phase structure and microwave dielectric properties of LaNbO 4 ceramics were investigated. The optimum sintering temperature of LaNbO 4 ceramics could be lowered from 1325 °C to 925 °C with the addition of BaCu(B 2 O 5 ) due to liquid phase sintering. X-ray diffraction patterns showed that single-phase LaNbO 4 could be achieved when BaCu(B 2 O 5 ) content is ≤ 1 wt%. However, with further increase in BaCu(B 2 O 5 ) content, small amount of second phases such as BaNb 3.6 O 10 and Ba 6 Nb 2 O 11 would be found. The variation trends of e r and Q × f value were similar to that of bulk density, the temperature coefficient of resonant frequency ( τ f ) could be affected by additives. Typically, LaNbO 4 ceramics with 1 wt% BaCu(B 2 O 5 ) sintered at 925 °C for 4 h possessed dense structure and exhibited enhanced microwave dielectric properties: e r = 21.2, Q × f = 22600 GHz and τ f = 10.01 ppm/°C.