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With the rapid advancement and integration of communication and sensor technologies, power system operation is becoming more vulnerable to cyberattacks, particularly attacks in which malicious data could induce catastrophic consequences on market operations. Financial risks, as well as the potential physical damages, raise growing concerns about the reliable operation of the electricity market. Existing market-targeting cybersecurity research has focused on developing attack strategies or detection schemes. However, the lack of cyber-vulnerability analysis (CVA) hinders operators from systematically evaluating the real-time (RT) market-clearing model and identifying potential threats from a cybersecurity perspective. This article proposes a comprehensive CVA model for delivering a detailed analysis of four aspects of vulnerability: highly probable cyberattack targets, devastating attack targets, risky load levels, and mitigation ability under different degrees of defense. Users can simulate interactions between attackers and defending operators under different attack events, and the corresponding market settlements are also obtained. The proposed bilevel model is recast into mixed-integer linear programming through Karush–Kuhn–Tucker (KKT) conditions. A simulation study on an IEEE-30 bus system demonstrates the accuracy and effectiveness of the proposed CVA model.

Conventionally, interface effects between polymers and fillers are essential for determining the breakdown strength and energy storage density of polymer-based dielectric composites. In this study, we found that interface effects between different fillers have similar behavior. BN and BaTiO3 fiber composite fillers with three different interface bonding strengths were successfully achieved by controlling composite processes (BT-fiber/BN

Traditional power market risk studies focus on systematic risk analysis which relies on value-at-risk (VaR) or conditional value-at-risk (CVaR) to measure potential financial losses resulting from renewable generation uncertainties. However, systematic risk only reflects the risk of a single entity and cannot capture the systemic risk which measures the risk contribution from a market participant to the overall market or the risk connection between two different market participants. With the rapid integration of renewable energy resources, it is essentially important to identify which renewable assets contribute a higher risk to market operations. Therefore, we propose two systemic risk measures, Contagious VaR (CoVaR) and marginal CoVaR (ΔCoVaR), to construct the risk connection network of the energy market under high renewable penetrations. Then, based on ΔCoVaR, a new index called normalized ΔCoVaR is built for market operators to evaluate the per MW impact on ΔCoVaR. Further, this paper proposes two approaches to manage the systemic risk in a day-ahead (DA) market, depending on regulation purposes. Finally, the proposed risk measures and management methods are applied to analyze a DA market with over 30% renewable energy penetration in a modified IEEE 118-bus system.

Inhibiting the recombination of photo-generated charge carriers remains one of the important challenges for photocatalytic materials nowadays. For this, we reported a series of novel bismuth layered structure ferroelectrics: M0.5Bi2.5Nb2O9 (M = Li, Na, K) nanosheets prepared by one-step hydrothermal method. The fabricated nanosheets with average thickness size of about 32 nm (Li0.5Bi2.5Nb2O9), 45 nm (Na0.5Bi2.5Nb2O9), 108 nm (K0.5Bi2.5Nb2O9) possess excellent photodegradation performance to various organic dye pollutants with high concentration of 20 mg/L [Rhodamine B (RhB), methyl orange (MO) etc.]. Interestingly, the degradation rate constants of RhB and MO can be further improved by polarization-induced charge separation under ultrasonic-assisted illumination condition, compared with those of light illumination alone, and increased by about 2.5 times for Na0.5Bi2.5Nb2O9 nanosheets. These findings make bismuth layered ferroelectric materials have a potential application in wastewater treatment as a kind of important photocatalysis.

Traditional cyberattack strategies on the electricity market only consider bypassing bad data detections. However, our analysis shows that experienced market operators can detect abnormal locational marginal prices (LMPs) under the traditional attack model during real-time (RT) operations, because such attack model ignores the characteristics of the LMP itself and leads to price spikes that can be an easy-to-detect signal of abnormality. A detection approach based on the concept of critical load level (CLL) is used to help operators identify risky periods when operators would be prone to overlooking abnormal LMPs. During safe periods, the abnormal LMPs are identified according to the operator's experience, while in risky CLL intervals, a N-x cyber contingency analysis is proposed to help independent system operators (ISOs) detect abnormal LMPs. Further, this paper constructs a new type of cyberattack strategy capable of not only bypassing bad data detection in the state estimation stage but also disguising the compromised LMPs as regular LMPs to avoid market operators’ alerts in a realistic scenario wherein the attacker has imperfect information on system topology. Finally, the proposed analysis method and the attack strategy are evaluated through numerical studies on the PJM 5-bus system and the IEEE 118-bus system.

In this work, Tb doped (K0.5Na0.5)NbO3 transparent ceramics were fabricated by a solid-state reaction method. The prepared samples not only exhibit high transmittance (67 % in visible light region and 73 % in IR region), but also show tunable transmittance ratio and luminescent modulation behavior via photochromic reactions. Specifically, the optical transmittance and luminescence intensity can be reversibly modulated by using 407 nm irradiation (20 s) and thermal stimulus (150 °C for 10 s) interchangeably. Their maximum transmittance and luminescence switching contrast are 26.29 % and 92.67 %, respectively. In addition, the various applications of optical data storage including process of data writing/erasing and optical marking have been depicted. The (K0.5Na0.5)NbO3: xTb transparent ceramics as a novel class of solid-state multifunctional materials would offer the prospect of enlarging the applications of photochromic ferroelectric materials.

Rational control of photoluminescence against a change in temperature is important for fundamental research and technological applications. Herein, we report an anomalous temperature dependence of ...

The intriguing coupling interactions between photochromism and ferroelectric polarization were firstly observed in Sm doped (K0.5Na0.5)NbO3 piezoceramics. After 407 nm irradiation, the maximum polarization (Pmax) and remanent polarization (Pr) intensities were dramatically decreased, whereas the coercive field, leakage current and photocurrent showed the remarkable increase. The variations of the polarization and photocurrent can be reversibly converted by alternating light irradiation and thermal stimulus, suggesting good polarization switching performance. This work provides a new route to effectively modulate ferro-/piezoelectric and photocurrent properties of ferroelectric materials by the non-contact remote control of light.

Antibiotic resistance genes (ARGs), as emerging environmental contaminants, are becoming a threat to human health. In this study, the combined processes of powdered activated carbon (PAC)/biological PAC (BPAC)–ultrafiltration (UF) were adopted to reduce the levels of ARGs in secondary effluents from a wastewater treatment plant. The removal of dissolved organic carbon (DOC) and the change of normalized flux in the UF process were investigated. In addition, the structural characteristics of the microorganisms of the BPAC were analyzed. The results showed that the appropriate dosage of PAC and BPAC was 40 mg/L. At this dosage, PAC/BPAC–UF combined processes could effectively remove the ARGs in secondary effluents by 1.26–2.69-log and 1.55–2.97-log, respectively; and the removal rates of DOC would be 60.7% and 54.1%, respectively. Relative to the direct UF, the membrane fluxes of the two combined processes were increased by 15.6% and 25.1%, respectively. Significant removal correlations were found between ARGs, intI1, DOC and 16SrDNA. These results revealed that the PAC/BPAC–UF combined process might play a promising role in ARG reduction in secondary effluents from wastewater treatment plants.

The (1-x) K0.5Na0.5NbO3-xNa0.5Er0.5TiO3 [(1-x)KNN-xNET] ceramics were fabricated by the traditional solid state reaction method. The effects of the NET content on their phase structure, microstructure, photochromism and photo-switching properties were systematically studied. The samples show bright green emission (530 nm, 551 nm) and red emission (660 nm) under 980 nm stimulation at room temperature. Upon visible light irradiation (407 nm), these samples change their color from the initial pale yellow to dark grey. And, luminescence emission intensity can be easily modulated by adjusting the degree of color change. In particular, the color and up-conversion emission can return its initial state by 230 °C thermal stimulation, showing excellent reversibility. These results make it potential applications in many fields such as luminescence switching and optical storage materials as a kind of multifunctional material.

(1-x)Na0.5Bi0.5TiO3-xBi(Mg0.5Ti0.5)O3 (NBT-BMT) thick films were designed for achieving large recoverable energy-storage density (Wrec). A large Wrec of 40.4 J/cm3 was detected in the thick film for x = 0.4, which was more than 4 times larger than that of the pure NBT film. The addition of BMT induced slim polarization hysteresis (P-E) loops at room temperature. The slim P-E loops improved the difference between the maximum polarization (Pmax) and the remnant polarization (Pr). Besides, a breakdown strength field (BDS) of 2440 kV/cm was also detected in the thick film for x = 0.4. The high BDS was caused by the reduced leakage current density. Furthermore, the thick film for x = 0.4 possessed superior energy-storage stability under different temperature, frequency and electric-field cycling. In addition, 90% of the pulsed discharge energy density could be released in less than 1100 ns by using a pulsed discharge measurement.

For luminescent photochromic materials, the optical properties of lanthanide (Ln) ions, including emission color, excitation mode and lifetime, are extremely important in optical information storage and recording. Conventional dopants of single Ln ions generally display unicolor and unimodal emission, leading to low-level luminescence modulation and information readout. Therefore, it is urgent to develop multicolor and multimodal luminescence modulation in a single photochromic material, thus well modulating luminescent readout capability. In this study, superior multicolor emissions (red-green), multimodal properties (downshifting/upconversion) and tunable luminescent switching contrast were successfully obtained in Bi2.5Na0.5Nb2O9-based ferroelectric materials by dual-lanthanide ion doping (Pr/Er). Red/green emission ratios can be continuously tuned from red, orange and yellow to green range via controlling the excitation wavelengths and doped concentrations. Correspondingly, the luminescent switching contrast (ΔRt) gradually increases from 29% to 93% with increasing excitation wavelength upon visible irradiation (407 nm), while the ΔRt values decrease with emission wavelengths, which can be well explained by the Dexter energy transfer model. These findings offer a guide to designing tailored luminescence modulation behavior of luminescent photochromic materials for wide application in optical storage and switching devices.

Solution self-assembly of a linear ABA triblock copolymer with two terminal crystallizable poly(ferrocenyldimethylsilane) (PFS) core-forming "A" blocks and a central poly(dimethylsiloxane) (PDMS) corona-forming "B" block has been investigated. The low dispersity (D = 1.05) copolymer, PFS26-b-PDMS584-b-PFS26 (block ratio 1.0:22.5:1.0), was prepared through a combination of living anionic polymerization and end-to-end coupling. The block ratio and dispersity were established by a combination of MALDI-TOF mass spectrometry, 1H NMR, and GPC. Individual 1D fiber-like micelles with looped PDMS coronas were formed in mixed solvents of hexane and decane. Low length-dispersity fiber-like micelles of controlled length were prepared from short seed micelles of PFS26-b-PDMS584-b-PFS26 derived from sonication using the seeded growth method termed living crystallization-driven self-assembly. In addition, seeded growth of blends of both PFS26-b-PDMS584-b-PFS26 and PFS26 homopolymer and of PFS26-b-PDMS584-b-PFS26 and the analogous diblock copolymer PFS26-b-PDMS292 were also explored. Large aggregates with fiber-like protrusions were formed by spontaneous nucleation of the blends of PFS26-b-PDMS584-b-PFS26 and PFS26. High-aspect ratio ribbon-like micelles were formed by adding the blends of PFS26-b-PDMS584-b-PFS26 and PFS26 to the cylindrical PFS26-b-PDMS584-b-PFS26 seeds. In contrast, surprisingly, seeded growth of blends of PFS26-b-PDMS584-b-PFS26 and PFS26-b-PDMS292 or the individual components using seeds of either PFS26-b-PDMS584-b-PFS26 or PFS26-b-PDMS292 showed that growth was only detected in the case of matching of the seed and multiblock copolymer chemistries.

In this work, reduced BaTiO3 (rBT) particles with a large number of defects sintered in a reducing atmosphere (95N2/5H2) were introduced into polyimide (PI) matrix without using any modifier or surfactant components. The rBT/PI composite films fabricated by an in situ polymerization method showed significantly enhanced dielectric constant and energy storage density. The dielectric constant of the rBT/PI composite with 30 wt% rBT reached up to 31.6, while maintaining lower loss (tg δ = 0.031@1000 kHz) compared to pure PI (er = 4.1). Its energy storage density (9.7 J cm−3 at 2628 kV cm−1) was enhanced by more than 400% over that of pure PI (1.9 J cm−3 at 3251 kV cm−1), and was greater than the energy density of the best commercial biaxially-oriented-polypropylenes (BOPP) (1.2 J cm−3 at 6400 kV cm−1). The energy storage efficiency was around 90% due to the linear dielectric performance of rBT/PI composite films. The improved dielectric constant and energy storage density could be attributed to the combined effect of the interface interaction between two phases and the surface defects of rBT induced by the reducing atmosphere. Therefore, rBT/PI composite films with high dielectric constant, energy storage density and storage efficiency may have potential applications in the preparation of embedded capacitors.

This paper discusses the turbulent flow and heat transfer from a uniform air flow with high temperature to the outside through a 90&deg, curved square pipe. Both conjugate heat transfer (CHT) simulation and experiments of temperature field measurements at cross sections of the pipe are performed. A straight pipe is investigated and compared with the 90&deg, curved pipe. The temperature of the air flow at the inlet of the pipe is set at 402 K, and the corresponding Reynolds number is approximately 6 &times, 104. To obtain the spatial average temperature at each cross section, the temperature fields are measured along the streamwise of the pipes and in the circumferential direction using thermocouples at each cross section from the inlet to the outlet of both the straight and curved pipes. Furthermore, the simulation is performed for turbulent flow and heat transfer inside the pipe wall using the Re-normalization group (RNG) k-&epsilon, turbulence model and CHT method. Both the experimental and numerical results show that the curvature of the pipe result in a deviation and impingement in the high-temperature core and a separation between the wall and air, resulting in a secondary flow pattern of the temperature distribution.

The increasing penetration of distributed PV systems challenges the distribution system voltage profile. When the system loading level is relatively low on a sunny day, the reverse power flow is expected to be large and the bus voltage is likely to exceed the upper bound. This paper conducts a sensitivity study on the Volt- VArcontrol of distributed PV systems for mitigating the overvoltage problem. The distribution system components, including the ZIP load, shunt capacitor and onload tap changer, are fully considered. The simulation study indicates that the Volt-VArcontrol can effectively reduce the daily maximum bus voltage and slightly reduce the network power loss. In addition, this control scheme does not require additional VAR compensation and communication devices. Therefore, it has great potential in future distribution systems if the PV penetration keeps increasing.

The high penetration of renewable energy incurs serious power fluctuations in the power system. Large scale electric vehicles (EVs) under the centralized control are able to provide considerable regulation capacity for the power system. In existing modeling methods for centralized EVs, the accurate control results for the regulation services were achieved by modeling each EV individually. However, the computational complexity was a serious problem for modeling large scale EVs. In this paper, a reduced modeling method for centralized EVs is developed by describing a population of EVs with a partial differential equation (PDE). This PDE modeling method uses a finite number of state-of-charge (SOC) intervals to describe the flows of charging EVs, idle EVs and discharging EVs. Considering the three connecting states (CNS) of EVs, this PDE modeling method realizes the power regulation for centralized EVs by changing the CNS of EVs located in different SOC intervals. Comparative simulations validate that the PDE modeling method for large scale centralized EVs achieves high control accuracy and high computational efficiency.

Since the emergence of digital hydraulic technology, it has achieved good results in intelligence, integration, energy saving, etc. After decades of development, and it has also attracted wide attention in the industry. However, for many years, the definition of digital hydraulic technology has differed between researchers, and there is no uniform definition. Such a situation affects the development of it to a certain extent. Therefore, this paper gives the exact definition of digital hydraulic technology based on a large number of researches on it. At the same time, the paper analyzes the research status and developmental process of the such a technology, and we forecast the development trend of it.

In this paper, the effectiveness of a semi-analytical BEM in studying the vibration mitigation of wave impeding block (WIB) in layered soil under horizontal loads is verified by field tests, subsequently the performance of WIB in mitigating the vibrations of ground subjected to horizontal-rocking excitations were investigated by numerical analysis using the verified BEM. Two types of layered half-space model under the horizontal-rocking excitations (site A: the stiff soil ground with relatively soft overlying soil layer, site B: the soft soil ground with relatively stiff overlying soil layer) are considered. Test and numerical results indicate that WIB can achieve desired vibration isolation effectiveness in layered soils under both the horizontal and horizontal-rocking coupled excitations. With the decrease of the embedded depth, the performance of WIB for vibration mitigation improves in layered ground under horizontal excitation. For horizontal-rocking coupled excitation, WIB reduces ground vibration by 50–70% at zones over one diameter of WIB (10 m) away from the vibration source; at zones within one diameter of WIB, peak AR value occurs, and the peak values are beyond 1.0 (2.0 in site A and 12.5 in site B at normalized distance D = 0.75) in radial direction. WIB behaves generally better in site A than in site B.

Dielectric materials with high energy-storage density and efficiency have great potential applications in modern electric and electronic devices. In this work, a series of 0.9(0.94Bi0.5Na0.5TiO3-0.06BaTiO3)-0.1NaNbO3 (BNT-BT-NN) ferroelectric thin films were deposited on LaNiO3 (LNO) bottom electrodes by radio-frequency (RF) magnetron sputtering technique. The effects of different annealing temperature on microstructure, dielectric property and energy-storage performance of these thin films were studied in detail. Post-deposition annealing of BNT-BT-NN thin films at an appropriate temperature of 650 °C was found to greatly improve the film structure and enhance the electrical characteristics, such as dense structure, smooth surface, low leakage current density, high breakdown strength (BDS) and large difference between maximum and remanent polarization. As a result, a huge energy-storage density of 32 J/cm3 and a large energy-storage efficiency of 90% were achieved under 3170 kV/cm in the thin film which was annealed at 650 °C. Moreover, the thin film exhibited a stable energy-storage performance under different temperature and frequency. Therefore, BNT-BT-NN thin film with proper annealing temperature is a promising candidate for high energy-storage capacitors.

[0.9(0.94Na0.5Bi0.5TiO3−0.06BaTiO3)−0.1NaNbO3]-xZnO (NBT-BT-NN-xZnO, x=0, 0.5 wt%, 1.0 wt%, 1.5 wt%, and 2.0 wt%) ferroelectric ceramics were fabricated using a conventional solid-state reaction method. The effects of ZnO content on dielectric, energy-storage and discharge properties were systematically investigated. Dielectric constant and difference between maximum and remanent polarization were significantly improved by ZnO doping. Dielectric constant of NBT-BT-NN-1.0-wt% ZnO was 3218 at 1 kHz and room temperature, i.e. one time bigger than that of pure NBT-BT-NN ceramic. As a consequence, a maximum energy-storage density of 1.27 J/cm3 with a corresponding efficiency of 67% was obtained in NBT-BT-NN-1.0-wt% ZnO ceramic. Moreover, its pulsed discharge energy density was 1.17 J/cm3, and 90% of which could be released in less than 300 ns. Therefore, ZnO doped NBT-BT-NN ceramic with a large energy-storage density and short release time could be a potential candidate for applications in high energy-storage capacitors.

Silicon is one of the most promising candidates for next-generation anode of Lithium-ion batteries. However, poor electrical conductivity and large volume change during alloying/dealloying hinder its practical use. Here we reported a three-dimensional (3D) nitrogen and sulfur codoped graphene supported silicon nanoparticles composite (SN-G/Si) through one-step hydrothermal self-assembly. The obtained SN-G/Si was investigated in term of instrumental characterizations and electrochemical properties. The results show that SN-G/Si as a freestanding anode in LIBs delivers a reversible capacity of 2020 mAh g −1 after 100 cycles with coulombic efficiency of nearly 97%. The excellent electrochemical performance is associated with the unique structure and the synergistic effect of SN-G/Si, in which SN-G provides volume buffer for nano Si as the flexible loader, short paths/fast channels for electron/Li ion transport as porous skeleton, and low charge-transfer resistance.

A beautiful and unique super long carbon tube network structure was synthesized via a freeze-drying technique and then carbonization of natural eggplant in a nitrogen atmosphere. Subsequently, nanorod-like FeOOH arrays were evenly grown on the surface of the carbon material via an easy and efficient hydrothermal process without any toxic chemicals. The composites grown for 5 h exhibited excellent performance, including a specific capacitance of 396 F g−1 within a potential window of −1.08 to 0 V at a current density of 0.5 A g−1 (2 times that of the pure eggplant derived carbon) and a good cycling stability (83% over 500 cycles at a current density of 10 A g−1). It is speculated that the synergistic effect of the super long hollow carbon tube network and the nanorod-like FeOOH arrays contributes to the fast electron transport and the battery-type capacitance behavior, respectively, thus enhancing the electrochemical performance. The above results indicate that the prepared nanocomposites are a potential negative electrode for supercapacitors.

White-light emitting organic materials attract broad attention which are ascribed to their potential for applications in lighting devices and display media. Most reported organic white-light emitters rely on the combination of several components that emit different colors of light (red/green/blue or orange/blue), which may cause problems to stability, reproducibility and device fabrication. By contrast, white-light emission from single-molecule systems offers opportunities to overcome these disadvantages, meanwhile engendering white-light with high quality. Nevertheless, limited cases of white-light emission at the molecular scale reported principally concentrate on organic solvents. Herein, we designed and synthesized new bi-functional organic molecules with a symmetric donor–acceptor–donor (D–A–D) type structure with the aim to construct a single-molecule white-light emitting system in aqueous solution. Further experiments and calculations demonstrate the possibility of stacking between the pyridinium-naphthalene (PN) core and coumarin groups in the designed molecules, ascribed to hydrophobic effects, π–π stacking and donor–acceptor interactions, which could dramatically enhance the intramolecular charge transfer (ICT) efficiency along with remarkable charge transfer (CT) emission. Based on this, multicolor photoluminescence including white-light can be finely tuned in various modes including excitation wavelength, solvent polarity, temperature, and host–guest interactions. A white-light emitting (WLE) hydrogel was also facilely prepared through the dispersion of one of the compounds in a commercial agarose gelator. This innovative study helps enrich the strategies to construct single-molecule organic white-light emitting materials in aqueous medium using the self-folding behavior.

Giant magnetoimpedance (GMI) always attracts much attention owing to its importance in promising applications of industrial devices. Although GMI effect of ribbons have been studied for years, the composite ribbons coated with various films are still attractive due to its high sensitivity with respect to the applied magnetic field. Mostly, the magnetic properties were commonly inspected by hysteresis loops, which may not sensitive enough for Fe-based composite ribbons. Herein, by using both hysteresis loops and the GMI measurement, the magnetic properties of the FINEMT ribbons coated with different thickness of Ni 80 Fe 20 film on free side, wheel side and twin sides have been thoroughly analyzed. It is revealed that the shift of anisotropy direction from preferable transverse to partially longitudinal as the film thickness increased, which affected the interaction between ribbon and Ni 80 Fe 20 coating. Moreover, the asymmetric GMI response could be obtained on the ribbon coated with Ni 80 Fe 20 film on single side, whereas the symmetric GMI response was observed for twin-side coating, which indicated the dipole interaction in the composite ribbons. We found that the ribbon with 260 nm Ni 80 Fe 20 film showed the optimized transverse anisotropy, leading to the smallest H c and the optimal soft magnetic properties. Hence, GMI measurement can be a sensitive alternative tool to investigate dipole interaction, which can be employed to manufacture novel linear GMI sensors and to properly regulate the operation field.

A novel 1,3-dicarbonyl-functionalized reduced graphene oxide (rDGO) was prepared by N-(4-aminophenyl)-3-oxobutanamide interacting with the epoxy and carboxyl groups of graphene oxide. The high-performance composite supercapacitor electrode material based on MnO2 nanoparticles deposited onto the rDGO sheet (DGM) was fabricated by a hydrothermal method. The morphology and microstructure of the composites were characterized by field-emission scanning electron microscopy, transmission electron microscopy, Raman microscopy and X-ray photoelectron spectroscopy. The obtained results indicated that MnO2 was successfully deposited on rDGO surfaces. The formed composite electrode materials exhibit excellent electrochemical properties. A specific capacitance of 267.4 F g−1 was obtained at a current density of 0.5 A g−1 in 1 mol L−1 H2SO4, while maintaining high cycling stability with 97.7% of its initial capacitance after 1000 cycles at a current density of 3 A g−1. These encouraging results are useful for potential energy storage device applications in high-performance supercapacitors.

Rare earth doped photochromic materials reveal great potential applications in optical memory storage devices due to their excellent reversible luminescence modulation behavior. Nevertheless, the unicolor emission and unimode luminescence modulation in photochromic materials by singly doped rare earth ions difficultly realize the effective optical data readout, then restricting their practical applications in display technology and multifunctional optical devices. Here, the multicolor and multimode luminescent modulation based on photochromic reactions were successfully obtained in Tb3+/Eu3+ co-doped (K0.5Na0.5)NbO3 system, utilizing the energy transfer engineering. The obtained samples exhibit excellent optical transparent (48% in visible light region and 61% in IR region) and multicolor emission from green, yellow-green, yellow, orange to red. After light irradiation, the emission intensity at 546 nm (green emission) and 612 nm (red emission) decreased significantly. The maximum luminescence switching contrast reach up to 68.93% (ΔRIgreen) of x = 0.004, and 69.77% (ΔRIred) of x = 0.016, respectively. The luminescence modulation ratio shows strong dependence on excitation wavelength and Eu contents, and optical transparent can also realize an effective reversible modulation based on photochromic reaction. The energy transfer from Tb3+ to Eu3+ forming two luminescent centers, then part of the energy is absorbed by color centers, which is the source of the multicolor emission and multimode luminescent modulation. These results may provide a new insight for designing multifunction transparent optical storage devices.

The immense potential of dielectric capacitor for use in energy-storage applications has propelled much recent research and development. Here, we prepared a kind of lead-free ferroelectric thick films of Fe-doped (Na0.85K0.15)0.5Bi0.5TiO3 (NKBT-Fex, x = 0, 0.01, 0.02 and 0.04). The effects of Fe3+ contents on the microstructure, dielectric properties and energy-storage performances of NKBT thick films were studied in detail. The studies on complex impedance spectroscopic were also carried out for NKBT-Fe0.02 thick film at different temperature from 100 Hz to 1 MHz. By Fe doping, the leakage current of the NKBT-Fex thick films was greatly reduced, while the breakdown strength (BDS) and the difference between the maximum polarization and remanent polarization were enhanced. These characteristics lead to excellent energy-storage performances with good temperature and frequency stability. In particular, a maximum energy-storage density (W) of 33.3 J/cm3 with an efficiency (η) of 51.3% was achieved in the NKBT-Fe0.02 thick film. These results open up a promising feasible route to enhance the energy-storage performances by properly element doping.

Anomalous basal stacking faults have frequently been observed inside 10 1 − 2 twins in deformed hcp metals. In this work, we report transmission electron microscopy observation of basal stacking faults inside 10 1 − 1 twins. These stacking faults present similar characteristics to those inside 10 1 − 2 twins. To reveal the formation mechanism, we performed atomistic simulations. The results show that the stacking faults are not mediated by partial dislocations. Lattice transformation analysis based on classical twinning theory shows that very large atomic shuffles (~ 0.16 nm) perpendicular to the twinning shear are required for twinning and responsible for the formation of these stacking faults.

Lead-free Na 0.5 Bi 0.5 Ti 1−x Mn x O 3 (NBTMn x , x=0, 0.01, 0.03 and 0.05) ferroelectric thick films have been fabricated on LaNiO 3 /Si(100) substrate by using a polyvinylpyrrolidone-modified sol-gel method and the effects of Mn content on their microstructure, dielectric properties and energy-storage performance were investigated. Compared with the pure Na 0.5 Bi 0.5 TiO 3 (NBT) thick films, NBTMn x thick films exhibited a large enhancement in dielectric properties and energy-storage performance. Particularly, a giant recoverable energy-storage density ( W ) of 30.2 J/cm 3 and the corresponding efficiency ( η ) of 47.7% were obtained in NBTMn 0.01 thick film at 2310 kV/cm. Moreover, the NBTMn 0.01 thick film displayed good energy-storage stability over a large temperature range at different frequency.

Sm-modified Na0.5Bi2.5Nb2O9 ceramics can simultaneously exhibit both visible light-driven photochromism and photoluminescence. Upon visible light irradiation, these materials change their color from green to dark gray, while exhibiting a strong red emission at 603 nm due to the 4G5/2 → 6H7/2 transition, whose emission intensity strongly depends on the irradiation wavelength, intensity, and time, and significantly decreases with increasing irradiation time and intensity. By alternating visible light or sunlight (λ > 400 nm) irradiation and thermal stimulus, both luminescence and absorption intensity can be reversibly switched without any significant degradation between the two colored and bleached states, with excellent reproducibility. On the basis of the trapped charge carrier and exponential relaxation decay models, we herein provide a detailed understanding of the photochromism and luminescence modulation mechanisms.

In this paper, we reported a new photosensitive material, Sm doped K0.5Na0.5NbO3 (KNN) ceramics, fabricated using a solid-sate reaction method, which exhibits both photochromism and luminescence switching properties. By alternating visible light irradiation (λ > 407 nm) and thermal stimulus, the samples show a reversible color change from the initial green to pale gray. Interestingly, luminescence emission intensity can be effectively tuned using photochromic reactions. Furthermore, the luminescence switching degree strongly depends on the firing temperature. These results suggest that KNN-based perovskite oxides with photochromism, luminescence switching and ferroelectric energy storage properties are particularly attractive for optical data storage applications as multi-functional materials.

Effects of thickness on dielectric properties and electrocaloric effect (ECE) of Pb 0.82 Ba 0.08 La 0.10 (Zr 0.90 Ti 0.10 )O 3 (PBLZT) antiferroelectric (AFE) thick films were systematically studied. As the thickness was increased, the Curie temperature of the thick films was increased, while their diffusing behavior was reduced. A giant reversible adiabatic temperature change of ΔT = 25.1 °C at room temperature was achieved in the PBLZT AFE thick film with a thickness of 1.0 μm. At the same time, the 1.0-μm-thick film had an electrocaloric coefficient of Δ T/ Δ E = 0.036 K cm/kV and a refrigeration efficiency of COP = 6.0 at room temperature. In addition, all samples had a low leakage current density of −6 A/cm 2 at room temperature. These results indicated that the PBLZT AFE thick films could be used for applications in solid-cooling devices by properly controlling their thickness.

Luminescence modulation based on photochromic reactions is always considered to be a promising method to achieve nondestructive readout in photochromic materials. Generally speaking, two conventional strategies have been widely used to achieve this target: tuning the absorption bands and adjusting luminescent quenching mechanisms. In this paper, we found a new strategy to improve effectively luminescence readout capability in Er/Yb codoped NBN-based solid-state inorganic photochromics by using a two-photon absorption mode of luminescent centers. Upon alternating visible light irradiation (407 nm) and the thermal stimulus, the materials exhibited a high luminescence switching contrast ratio (ΔRt = 86%), excellent reversibility, and significantly improved luminescent efficiency (22 times). Most importantly, the photochromic reaction process can be efficiently read out using the two-photon absorption (or up-conversion) mode without inducing any new reactions, showing extremely low destruction on information recording (destruction degree

Luminescent switching materials upon photochromic reactions have potential applications in optical switching and high-density optical data storage in optoelectronic devices. To avoid interference and destruction of information in practical data storage applications, a nondestructive luminescence readout is essential. However, it is still unclear how to select the optimized excitation and emission bands to avoid the photochromic reaction during the “reading” process while maintaining high luminescence contrast and stability in inorganic photochromic materials. On the basis of the nonradiative energy transfer mechanism, Ho3+ ions were introduced into the Na0.5Bi2.5Nb2O9 host to obtain efficient luminescence switching due to their special excitation (451 nm) and emission (547 nm) characteristics. Under 407 nm irradiation (“writing”), the photochromic phenomenon can be effectively read out by measuring the changes in the luminescence emission intensity. The luminescence switching contrast increased up to 94%. Importantly, the excitation and emission energies did not significantly induce new photochromic reactions, causing less destruction to the material and the luminescence readout process. This outcome is superior to our previously reported results. Furthermore, the luminescence switching properties exhibit hardly any degradation after undergoing several cycles of the “writing”, “reading” and “erasing” processes, indicating excellent reversibility.

Evolutionary and scalarization methods are the most common algorithms of solving power system multi-objective problems. However, it is challenging to calculate Lagrangian multipliers for each objective directly by these two methods. The lack of an effective algorithm for performing sensitivity analysis on power system multi-objective problems prevents the collection of important information for market studies. In this paper, a sensitivity matrix formulation method for power system multi-objective problems is proposed and applied to the economic emission dispatch problem (EED). An emission related locational marginal price is first formulated and then decomposed regarding the cost objective and the emission objective. Then, a detailed sensitivity analysis of EED is performed on the IEEE 30-bus system to investigate the influence of resources on operation costs and pollutions.

The high penetration of large-scale renewable generations challenges the stability of power systems. It is likely to causes frequency fluctuations due to the intermittent nature. Demand Response (DR) has received much attention because it balances generation and demand with flexibility. Unlike the costly conventional spinning reserve, thermostatically controlled load (TCL) can be controlled to provide frequency regulation service with little impact on customer comfort. A progressive demand control strategy is proposed in this paper for the system frequency regulation. In particular, the state shift priority method is proposed to optimally control loads without compromising customer comfort. The operation-cycle based random recovery method is developed to mitigate the load rebound. Case studies are conducted to validate that TCLs can provide a fast and smooth frequency regulation via the proposed control strategy.

In the past few decades, many bridges have been built. How to ensure the safety and durability of these bridges has become an important issue in the field of bridge engineering. Among them, the loss of the cross-sectional area of cables is a common damage and severely area loss-induced damage in bridge cables could break wires to cause bridge failures. The loss of metal area refers to corrosion inside the cable, missing wire or broken wire of the cable within a certain length of the longitudinal direction. These all make detection a very important issue for the health and maintenance of bridge cables. Magnetic flux examination can be used in analyzing the collected signals and solving many problems in the magnetic field. In this study, magnetic flux examination was used to detect the bridge cable defects based on its good performance in detecting wire rope defects. Theoretical derivation for a quantitative identification method has been finished recently. Finite element simulation and laboratory experiments were performed to evaluate the quantitative identification method and identify the uniform corrosion damage of steel wires. The characteristics of the magnetic flux detection signal of the cables in different types of defects and different equipment parameters’ influence were investigated. Furthermore, the proposed defect length coefficient was used to correct the magnetic flux signal, and it is proved that the defect length coefficient is effective in improving the accuracy of quantitative identification of short defects in the experiment.

Four-dimensional (4D) active shape-changing structures based on shape memory polymers (SMPs) and shape memory nanocomposites (SMNCs) are able to be controlled in both space and time and have attracted increasing attention worldwide. However, conventional processing approaches have restricted the design space of such smart structures. Herein, 4D active shape-changing architectures in custom-defined geometries exhibiting thermally and remotely actuated behaviors are achieved by direct-write printing of ultraviolet (UV) cross-linking poly(lactic acid)-based inks. The results reveal that, by the introduction of a UV cross-linking agent, the printed objects present excellent shape memory behavior, which enables three-dimensional (3D)-one-dimensional (1D)-3D, 3D-two-dimensional (2D)-3D, and 3D-3D-3D configuration transformations. More importantly, the addition of iron oxide successfully integrates 4D shape-changing objects with fast remotely actuated and magnetically guidable properties. This research realizes the printing of both SMPs and SMNCs, which present an effective strategy to design 4D active shape-changing architectures with multifunctional properties. This paves the way for the further development of 4D printing, soft robotics, flexible electronics, minimally invasive medicine, etc.

High luminescent switching contrast of photochromic materials is extremely important in improving the sensitivity and resolution of optical switches and high-density optical data storage devices. To date, conventional methods, such as tuning absorption and emission bands based on electron or resonance energy transfer mechanisms in well-known organic photochromic molecules or compounds, have routinely been adopted to tune luminescent switching behavior. However, these strategies and mechanisms are not effectively applied to luminescence switching in inorganic materials because their crystal structures differ strongly from those of organic materials. In this paper, we report a new method to significantly tune the luminescent switching contrast by modifying the excitation energy of luminescent centers in a newly synthesized photochromism material: Na0.5Bi4.5Ti4O15:Re (Re = Sm, Pr, Er). A significant enhancement of luminescence switching contrast was achieved when the luminescent centers were excited by low e...

In this work, (111)-oriented (Pb0.99Nb0.02)(Zr, Sn, Ti)0.98O3 (PNZST) antiferroelectric thin films, which located in the tetragonal phase region (PNZSTT) and the orthorhombic phase region (PNZSTO), respectively, were successfully fabricated on platinum-buffered silicon substrates by radio-frequency magnetron sputtering technique. The microstructure, dielectric properties, electric field induced phase transition, associated with the energy-storage performance and pyroelectric energy harvesting behavior (by Olsen cycle) were studied systemically. The PNZSTT thin film showed a diffused field-induced antiferroelectric–ferroelectric (AFE–FE) phase switching with a slim double hysteresis loop, while the PNZSTO film demonstrated an AFE–FE phase switching with a square double hysteresis loop. A maximum recoverable energy-storage density of 16.4 and 12.4 J/cm3 were obtained in the PNZSTT and PNZSTO film, respectively. Moreover, a huge harvested energy density per cycle of W = 7.35 and 5.35 J/cm3 was also predicted in the PNZSTT and PNZSTO film at 1 kHz, respectively. The good energy-storage performance and giant thermal-electrical energy harvesting effect of the PNZST antiferroelectric thin films maybe make a great impact on the modern energy-storage technology and the thermal-electrical energy harvesting applications.

The energy-storage performance and dielectric properties of tape-cast (Pb 0.92 Ba 0.05 La 0.02 )(Zr 0.68 Sn 0.27 Ti 0.05 )O 3 (PBLZST) antiferroelectric (AFE) thick films with different thicknesses were systematically studied. As the thickness of the thick films increased from 40 to 80 µm, the dielectric constant and saturation polarization ( P s ) of the thick films were gradually increased, while their corresponding breakdown strength (BDS) was decreased. A maximum recoverable energy-storage density of 6.8 J/cm 3 , companied by an efficiency of 61.2%, was achieved in the PBLZST AFE thick film with a thickness of 40 µm at room temperature. Moreover, the energy density of the PBLZST AFE thick films also displayed good thermal stability over 25–200 °C. In addition, all the samples had a low leakage current density of ~10 −6 A/cm 2 at room temperature. These findings demonstrated that the PBLZST thick films should be a promising candidate for applications in high energy-storage capacitors.

The effects of grain size on dielectric properties, energy-storage performance and electrocaloric effect (ECE) of Pb0.85Ba0.05La0.10(Zr0.90Ti0.10)O3 (PBLZT) antiferroelectric thick films were systematically studied. As the grain size was increased, dielectric constant of the thick films was increased, while their critical breakdown field was decreased. A giant reversible adiabatic temperature change of ∆T = 19.9 °C at room temperature was achieved in the PBLZT AFE thick film with a grain size of 0.59 µm. However, a huge recoverable energy-storage density of 33.6 J/cm3 and a high efficiency of 73 % were observed in the film with the smallest grain size of 0.19 µm at its breakdown field, because of its excellent electric field endurance. In addition, all the samples had a low leakage current density of below 10−6 A/cm2 at room temperature. These results indicated that our PBLZT AFE thick films could be a promising candidate for applications in high energy-storage density capacitors and solid-cooling devices by properly controlling their grain size.

In this work, (Pb0.92Ba0.05La0.02)(Zr0.68Sn0.27Ti0.05)O3 (PBLZST) antiferroelectric (AFE) ceramics with the addition of PbO–B2O3–SiO2 raw glass powder as sintering aid were prepared via the microwave sintering method. The effects of glass content on the electrical properties and energy-storage performance of the ceramics were investigated in detail. With the glass content increasing, dielectric constant of the ceramics gradually decreased, while the breakdown strength increased. A maximum recoverable energy-storage density was about 2.3 J/cm3 and the corresponding efficiency was about 76.8 % to be achieved in the ceramics with 3-wt% glass at room temperature. The energy density of the PBLZST AFE ceramic with 3-wt% glass is 1.3 times as that (1.8 J/cm3) of the pure specimens. These results indicated that the energy-storage performance of AFE ceramics could be improved by adding proper glass and selecting novel sintering method.

Functional physical behavior, including triple shape memory process and reversible actuation, has attracted great interest in the research field of thermosetting polymers in recent years. Herein, we synthesized a series of covalent crosslinking thermosetting polymers with triple shape memory effects via introducing bisphenol-A cyanate ester (BACE) to bismaleimide (BMI) networks. Due to the complex covalent crosslinking structures, such BMI based triple-shape memory polymers (TSMPs) present broad glass transition temperature ranges, which is a crucial precondition for the triple-shape memory behavior. Results demonstrated that BMI based TSMPs showed excellent thermal stabilities and mechanical properties. Moreover, triple shape memory behavior was achieved successfully by choosing two switching temperatures to fix two separate shapes independently. Upon heating, both the programmed shapes could recover to their former shape separately. This paper provides fundamental attempts for the further development of thermosetting triple shape memory polymers. Combining the superior comprehensive properties with the smart triple shape memory behavior, such materials present great potential to be applied as smart materials and structures, especially for aerospace areas.

Based on the China Spallation Neutron Source (CSNS) – Back-streaming white neutron source (Back-n WNS), the measurement of the U-238/U-235 fission cross section ratio in 1–20 MeV neutron energy region has been carried out by a multi-cell fast fission ionization chamber using the time-of-flight method. The measured resonance peaks of the 235U(n, f) reaction are in good agreement with those of the ENDF/B-8.0 database. The measured six groups of the U-238/U-235 fission cross section ratios in 1–20 MeV neutron energy region agree with those of the ENDF/B-8.0 database in trend, and the average discrepancies between experiment and database are from 1.9% to 2.6%. The relative experimental uncertainties are 2.3%–3.6% (1.4–20 MeV), and the measured data agree with those of database within experimental uncertainties at most energy points. The measured U-238/U-235 fission cross section ratio could provide information and data support in relevant nuclear data evaluation.