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Compared with the conventional drilling, the helical milling has obvious advantages in making holes of carbon fiber-reinforced plastic (CFRP). Nevertheless, the rapid wear of cutting edges readily causes some defects in the outlet holes, such as burrs and tearing. In order to improve the hole-making quality of CFRP, a comparative experimental study on conventional and ultrasonic-assisted bi-directional helical milling of CFRP was carried out. The wear mechanism of the forward and reverse cutting edges was analyzed in the two types of machining, and the change laws of cutting forces and hole wall quality were obtained by different machining means. The experimental results indicated that the flank face of forward and reverse cutting edges was dominated by the abrasive wear mechanism in the ultrasonic-assisted milling. With aggravation of the tool wear, no obvious coating peeled off the forward cutting edge, the reverse cutting edge remained relatively intact, and the wear form of neither cutting edge changed. Furthermore, in the ultrasonic-assisted reverse milling, the axial force and hole diameter deviation were restrained better than in the conventional milling, and especially when the tool wear occurred, the cutting force fluctuation varied slowly. In the ultrasonic-assisted milling, the shear fracture predominated over bending fracture. Meanwhile, the time variation of effective rake angles improved the chip breaking and removing performance of cutters, and thus, the machining quality of hole wall was enhanced obviously.

Urban haze has a multiple hazard in human living environment. It is not only harmful to human health but also affects the light passing through the atmosphere. This paper presents a study explainin...

Inverted planar perovskite solar cells (PSCs) with poly(N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine) (PTPD) layer as hole-transporting layer (HTL) exhibit high power conversion efficiencies (PCEs) over 20%. However, the influence of PTPD’s molecular weight (Mw) on the performance of PSCs has not been reported yet. Herein, we employ PTPD with various molecular weights as HTL to fabricate highly efficient inverted planar PSCs. Our results show that PTPD with 75 kDa possesses superior conductivity, which can quicken the charge carrier extraction from perovskite to HTL. In addition, the MAPbI3 perovskite film atop the 75-kDa PTPD is smoother with higher crystallinity and lower defect density. As a result, inverted planar PSCs with 75-kDa PTPD as HTL deliver a highest PCE of 19.24%. Our work provides a beneficial reference for future preparation of stable and highly efficient inverted PSCs with polymer HTL.

Functionalized knitted fabric, as a kind of flexible, wearable, and waterproof material capable of conductivity, sensitivity and outstanding hydrophobicity, is valuable for multi-field applications. Herein, the reduced graphene oxide (RGO)-coated knitted fabric (polyester/spandex blended) is prepared, which involves the use of graphite oxide (GO) by modified Hummers method and in-situ chemical reduction with hydrazine hydrate. The treated fabric exhibits a high electrical conductivity (202.09 S/cm) and an outstanding hydrophobicity (140°). The outstanding hydrophobicity is associated with the morphology of the fabric and fiber with reference to pseudo-infiltration. These properties can withstand repeated bending and washing without serious deterioration, maintaining good electrical conductivity (35.70 S/cm) and contact angle (119.39°) after eight standard washing cycles. The material, which has RGO architecture and continuous loop mesh structure, can find wide use in smart garment applications.

In order to study the cumulative blasting stress wave produced by the vibration of soft rock slope, the deformation regularity of the influence of blasting, caused by the horizontal and axial acceleration along with other additional stress waves were analyzed. The vibration displacement formula along with the vibration source stress wave superimposed model were established. The research also deduced the deformation rule for the gangue slope of Lijiahao Coal Mines as a vibration signal recorder was used to collect the blast vibration wave and the simulated analysis of displacement monitoring profile of the X and Y displacement rule under the influence of blast vibration were obtained. The results indicate that with the increase of the shot point distance, the displacement in the Y direction shows a logarithmic decline rule while the change in displacement of the X direction is small. The result also shows that the greater the initiation of multipoint shot firing, the greater the slope deformation and displacement of the rock mass and as a result multipoint nonsimultaneous blasting and control detonation time difference, can effectively reduce the effects of vibration on the slope deformation.

Wide-band gap (WBG) mixed-halide perovskites have drawn much attention because of their excellent optoelectronic properties and the potential to be deployed in tandem solar cells. Nevertheless, the bromine incorporation inevitably leads to photoinduced phase segregation in WBG mixed-halide perovskites. Herein, potassium is used to effectively suppress photoinduced phase segregation, which is visualized with confocal photoluminescence microscopy imaging. Strikingly, the potassium passivation not only inhibits the formation of the narrow-band gap subphase but also enhances the crystallinity of the WBG mixed-halide perovskite. In addition, the potassium-passivated WBG perovskite exhibits lower defect density, longer charge carrier lifetime, and better photostability. As a result, the optimized KI (2 mol %)-passivated WBG perovskite solar cells (PSCs) deliver a champion power conversion efficiency of 18.3% with negligible hysteresis. They maintain 98% of their initial efficiency after 400 h under 100 mW·cm

Red mud as the main byproduct generated during alumina extraction from bauxite. Owing to the high iron content in the red mud and the high correlation between iron and scandium during the leaching ...

For the Guanshui Road Station tunnel project of Guiyang Metro Line 2, the wind pavilion group was moved out of the main tunnel to reduce the number of openings in the main tunnel, and the wind pavilion group was excavated in a triangular configuration at the entrance of the main tunnel. Based on the finite element software ABAQUS, a three-dimensional model is established to study the influence of different triangular-distribution tunnels excavation schemes on the surface settlement and tunnel stability. The objective of this study is to reveal the change rules of surface settlement, deformation and force in the support structures and the surrounding rock and identify the best excavation scheme for this tunnel configuration. Results show that to control the surface settlement and the deformation of the support structures, the optimal excavation sequence involves excavating the upper fresh air exhaust tunnel before the lower running tunnel. To control the stress of the support structures, the optimal excavation involves excavating the lower running tunnel before the upper fresh air exhaust tunnel. In this project, the most reasonable excavation sequence of the tunnel is from top to bottom. The most reasonable thickness of tunnel penetration is 5 m.

For oil fields, shooting target range, military forbidden zones and other special complex scenarios, it is not only difficult to deploy communication infrastructure because of its remote location and difficult environment, but also difficult to transmit surveillance video images to command stations in real time through centralized communication networks. Furthermore, there is a waste of bandwidth resources and the use of wireless ad hoc networks to transmit surveillance video. Therefore, we aim at designing and implementing a real-time intelligent surveillance system based on wireless ad-hoc networks in special scenes in this project. The system is supposed to capture the video frames of the monitored area and perform automatic intrusion detection. Only when an intrusion is detected, the video frame is encoded and transmitted together with the alarm message to the command center. An improved Yolov2 algorithm to achieve real time object detection on a computationally limited platform was proposed first. A wireless ad-hoc communication system was designed and implemented on the basic of the Tactical Targeting Network Technology (TTNT) Data Link to transmit surveillance video stream, control signaling and alarm message. Then the extensive experiments were conducted to evaluate the system in terms of detection accuracy and communication performance. The experiments results demonstrate the effectiveness and accuracy of the proposed system, the size of the model is only 7.6% of Yolov2 and the detection speed is increased 4 times. This design transforms long-time data transmission into burst data transmission, thus saving bandwidth resources and improving bit error rate of 96.9%. It is of great significance for the future application of artificial intelligence and machine learning in the field of communication

BaCu2-xCoxSi2O7 solid solutions with orthorhombic structure (Pnma) were prepared by solid-state reaction method. The phase synthesis process, structural evolution and microwave dielectric properties of BaCu2-xCoxSi2O7 ceramics were investigated. Single BaCu2Si2O7 phase was obtained when calcined at 950 °C for 3 h and was decomposed into BaCuSi2O6 phase when calcined at 1075 °C for 3 h. The sintering process was effectively promoted when Cu2+ was replaced by Co2+ and the maximum solubility of BaCu2-xCoxSi2O7 was located between 0.15 and 0.20. P-V-L complex chemical bond theory and Raman spectra were used to explain the structure-property correlations of BaCu2-xCoxSi2O7 ceramics. The corrected dielectric constant (er-corr) of BaCu2-xCoxSi2O7 ceramics decreased monotonously with the susceptibility (Σχμ) and ionic polarizability of primitive unit cell. The quality factor (Q × f) increased with bond strength and lattice energy (Ucal), especially the lattice energy of the Si-O bond. The temperature coefficient of resonant frequency (τf) was determined by the susceptibility and lattice energy of the Cu/Co-O bond. The following optimum microwave dielectric properties were obtained at x = 0.15 when sintered at 1000 °C for 3 h: er = 8.45, Q×f =58958 GHz and τf = -34.4 ppm/°C.

During hole making of carbon fiber reinforced plastic (CFRP) by helical milling, the tool wear is a main factor in machined surface damage, being unable to guarantee machining quality and accuracy, and restricting the improvement of hole making efficiency. In order to prolong the service life of cutters, this paper has carried out the research into the design, manufacture, and cutting performance of stepped bi-directional milling cutters, combining with hole making of CFRP by bi-directional helical milling. By the method of differential geometry, the geometric model of the profile shape and the mathematical model of the helical edge are established of the stepped bi-directional milling cutter. Additionally, based on the transformation matrix between grinding wheel and workpiece coordinates of any point, the track equation of grinding wheel is derived from grinding the side edge helical groove of the stepped bi-directional milling cutter. What is more, the grinding process and accuracy are measured about the designed stepped bi-directional milling cutter. The experiment of CFRP holes made by bi-directional helical milling is designed, and the experimental results show that the axial cutting force of stepped bi-directional milling cutters is smaller and fluctuates more gently than that of symmetrical bi-directional milling cutters in the backward milling. Especially, the former has better distributed and slower flank wear on the backward cutting edge, and better machining quality than the latter.

As one of the most influential factors leading to gear vibrations, transmission errors of the engaging gears must be controlled to achieve a desirable dynamic performance for a power transmission system. It is well known that tooth modification is an effective way to reduce the fluctuations of the transmission error of a gear pair. The challenge is determining how to establish a quantitative relationship between the tooth modification parameters and the transmission error fluctuations of a gear pair. The present study aims to reveal the sensitivity of the tooth modification parameters on the transmission error fluctuations of a helical planetary gear train in a wind turbine gearbox. For this purpose, a sophisticated parametric three-dimensional contact model that included the micro-geometries of the tooth modification is developed in the ROMAX® environment. Based on this model, a loaded tooth contact analysis is carried out to compute the meshing characteristics, such as the contact pressure and transmission error of each gear pair in the planetary gear train. With the obtained meshing characteristics, the tooth modification amounts of the engaging gears were determined using empirical formulas. These modification amounts are designated as the mean values of the samples generated by the central composite method. After repeating the loaded tooth contact analysis process for each generated sample, a quadratic polynomial function is derived using the response surface method to describe the quantitative relationship between the tooth modification parameters and the dynamic transmission error fluctuations. A large number of random samples are generated using a Monte Carlo method, and the corresponding dynamic transmission error fluctuations are determined with the aforementioned quadratic polynomial function. Based on these samples, a reliability sensitivity analysis is carried out to demonstrate the effects of the tooth modification parameters on the dynamic transmission error fluctuations of the helical planetary gear train.

Organic heterostructures (OHSs) consist of organic micro/nanocrystals are of essential importance for the construction of integrated optoelectronics in the future. However, the scarcity of materials and the problem of phase separation still hinder the fine synthesis of OHSs. Herein, based on the α phase one-dimensional (1D) microrods and the β phase 2D microplates of one organic compound 3,3′-((1 E ,1′ E )-anthracene-9,10-diylbis(ethane-2,1-diyl))dibenzonitril ( m -B2BCB), we facilely synthesized the OHSs composed of these two polymorph phases, whose growth mechanism is attributed to the low lattice mismatch rate of 5.8% between (001) plane of α phase (trunk) and (010) crystal plane of β phase (branch). Significantly, the multiport in/output channels can be achieved in the OHSs, which demonstrates the structure-dependent optical signals with the different output channels in the OHSs. Therefore, our experiment exhibits the great prospect of polymorphism in OHSs, which could provide further applications on multifunctional organic integrated photonics circuits.

Red mud is the main solid waste generated by the aluminum industry for the extraction of alumina. Considering the environmental problems associated with red mud, the recovery of iron from bauxite s...

The measurement of the echo time delays and phases of the surface acoustic wave (SAW) tag by the corresponding reader should be more accurate with the increase of the coding capacity, and the design of the high-speed data acquisition module (DAM) is the key factor for the improvement of the reader performance. Aiming at the large capacity SAW tag, which combines pulse time delay and phase coding, the radio-frequency (RF) band-pass sampling and digital quadrature demodulation scheme is utilised for the reader design. The design of the high-speed DAM includes the analysis, calculation and determination of the sampling frequency, the sampling clock design with cascaded phase-locked loop structure and the driver circuit design etc. Finally, the SAW RFID system is established, and the time delays and phases of the tag reflectors are tested. The measurement results show the effectiveness of the high-speed DAM of the reader.

In this paper, we used the thermal evaporation method to deposit K-doped NiO (KNO) films as the inorganic buffer layer in thermally activated delayed fluorescence (TADF)-based organic light emitting diode (OLED) devices, and investigated how it improved device performance. The device configuration was ITO/NiO:K2CO3 (X mol%, 1 nm)/NPB (40 nm)/CBP:4CzIPN (5 wt%, 20 nm)/TPBi (50 nm)/LiF (1 nm)/Al (150 nm). We used various concentrations of alkali metal-doped metal oxide on the ITO, which was then subjected to UV-O3 surface treatment. We studied the effects and mechanisms of the improved hole-injection properties of the OLEDs with different measurement methods. X-ray Photoelectron Spectroscopy (XPS) was used to measure the molecular binding energy and confirm formation of the K-doped NiO films. In comparison with the ITO electrode's work function, the KNO film increased the work function from 4.8 to 5.3 eV. Contact angle measurement showed that the deposition of the buffer layer increased both polarity and surface energy. The K-doped NiO film was found to have a smoother surface than that of the ITO electrode, as determined by Atomic Force Microscopy. Reduction in the sheet resistance of the OLEDs was revealed by Admittance Spectroscopy measurement. The opto-electrical performances of the devices showed an increase in luminance from 18420 cd/m2 to 36740 cd/m2, a decrease in turn-on voltage from 4.3 V to 3.9 V at 100 cd/m2, and an increase in external quantum efficiency (EQE) from 7.1% to 9.76% when a 1-nm-thick KNO film with a doping concentration of 1 mol% was inserted into the OLEDs.

Organic semiconductor molecules that ideally suitable for being used to achieve solid-state lasers (OSSLs) in aggregate-state cannot actually act as the efficient laser gain materials due to variet...

Micro-polluted river water is characterized as having limited biodegradability, low carbon to nitrogen ratio and little organic carbon supply, all of which makes it hard to further purify. Two bench scale constructed wetlands (CWs) with a horizontal subsurface flow mode were set up in the laboratory to evaluate their feasibility and efficiency on denitrification with and without corn cobs as external carbon sources. Micro-polluted river water was used as feed solution. The CW without corn cobs substrates possessed a good performance in removing chemical oxygen demand (COD

Inhalable environmental toxicants can induce pulmonary malfunction resulting abnormal respiratory conditions. The traditional methods currently available to detect the respiratory condition of animals rely on differential pressure transducers and signal amplifiers. In comparison, current machine vision application requires little hardware. But it is unsuitable for respiratory condition tests of experimental animals reflecting respiratory toxicities of inhalable pollutants. In this study, we establish a new automatic method of machine vision analysis using a model that has mice inhaling aqueous aerosol with different concentrations of CdCl2 (0, 1, 3, 5 mM 2 h/day) for 7 days as simulant occupational exposure of inhalable Cd and analyze respiratory conditions such as respiratory rate, rhythm index, drive index and exchange index. Additionally, the models with different degrees of lung damage in mice are further tested and verified by the concentrations of cadmium accumulated in the lungs and the analyses on pulmonary porosity, fibrosis and inflammation. Machine vision analysis can identify the abnormal respiratory conditions of mice. Respiratory rate and rhythm index increase after exposure to cadmium. In the individuals with mild lung damage, respiratory drive index and exchange index in treatment group are higher than that in the control group, and in individuals with severe lung damage, these indices are similar to that of the control group. These abnormal respiratory conditions related to variable lung damage in mice demonstrate that the respiration is synchronously influenced by inhalable Cd and respiratory compensation according to normal physiological regulation, suggesting the present method is effective.

Two low cost hexa-substituted benzene derivatives, namely HFB-OMeDPA and HPB-OMeDPA, have been successfully utilized as hole transporting materials (HTMs) for efficient perovskite solar cells (PSCs). The relationships between molecular structure, electronic properties of the semiconductor and eventually the photovoltaic performance are investigated. The planar PSCs employing HPB-OMeDPA as HTM exhibit excellent power conversion efficiencies exceeding 16% under AM 1.5G illumination conditions, which are comparable to the reference cells based on spiro-OMeTAD.

A novel polyacrylamide (PAM) / sodium alginate (SA) adsorbent with double network structure was prepared by emulsion polymerization of acrylamide (AM) and SA. The chemical structure, thermal stability, crystallinity, pore size and distribution, surface area, surface morphology and energy dispersive spectrum of PAM/SA microspheres were determined by FTIR, TGA, XRD, BET, SEM and EDS. In addition, the effects of pH, temperature and adsorbent dosage on the adsorption capacity of Methylene blue (MB) were evaluated. The adsorption isotherms and kinetics as well as the thermodynamics of adsorption process were also studied. The results show that due to the entanglements between PAM and SA molecular chains. A double network structure is formed. The introduction of SA leads to the decrease of thermal stability and crystallization ability of PAM. The pore size is in the range of 0–200 nm, and the mesoporous structure is uniform. The particle size of is in the range of 1–10 u m. The surface of PAM/SA composite microspheres is smooth, and the ion crosslinking point is uniformly distributed. The results show that when pH=6, temperature is 25℃ and adsorbent dosage is 0.1g, the maximum adsorption capacity of PAM/SA composite microspheres is 75 mg/g. Langmuir isothermal model has better correlation with MB adsorption, and the maximum capacity obtained by simulation is 1070.54 mg/g. The pseudo-first-order kinetics and adsorption thermodynamics are better. The adsorption process is a physical adsorption rather than the chemical interation. The adsorption force decreases with the increase of temperature. The obtained PAM / SA composite microspheres have excellent adsorption capacity for dye removal from wastewater.

In order to enhance the tracking performance and improve the stability of intelligent electric vehicles, combined Lane keeping and direct yaw moment control is a good choice. In this paper, an uncertain model of intelligent electric vehicles for combing the lane keeping and direct yaw moment control is deduced, in which time delay and data dropouts are involved. Since the intelligent electric vehicles have the features of time delay and strong uncertainties, a novel robust guaranteed cost combined lane keeping and direct yaw moment control system is constructed to manage the lateral motion of intelligent electric vehicles. The asymptotic stability of combined lane keeping and direct moment control system is verified based on the Lyapunov stability theory. Simulation tests are carried out to demonstrate the feasibility of the proposed control approach, and the results indicate that the presented robust combined control approach can accurately achieve the lane tracking capability, stability and maneuverability of intelligent electric vehicles.

Unsupervised feature selection is an important machine learning task since the manual annotated data are dramatically expensive to obtain and therefore very limited. However, due to the existence of noise and outliers in different data samples, feature selection without the help of discriminant information embedded in the annotated data is quite challenging. To relieve these limitations, we investigate the embedding of spectral learning into a general sparse regression framework for unsupervised feature selection. Generally, the proposed general spectral sparse regression (GSSR) method handles the outlier features by learning the joint sparsity and the noisy features by preserving the local structures of data, jointly. Specifically, GSSR is conducted in two stages. First, the classic sparse dictionary learning method is used to build the bases of original data. After that, the original data are project to the basis space by learning a new representation via GSSR. In GSSR, robust loss function $$\ell _{2,r}{-}{norm}(0

Purpose The purpose of this paper is to advance a digital technology that is intended to bring about innovations on the existing textile patterns. Design/methodology/approach The pattern is deemed as a relation function between colors and positions which can be learnt by the artificial neural network (ANN). The outputs of the ANN are used for the reconstruction of the pattern and the innovation is performed by interceptors in the input/output layer. The ANN is carried out with one input layer, one output layer and several hidden layers, and the capacity of the architecture is adjusted by the scale of hidden layers to accommodate different function relations of the patterns. The training is conducted repeatedly on a sample set extracted from the pixels of the pattern image to minimize the error, and the chromatic outputs of the architecture are replaced to their origins so as to rebuild the pattern. Then, the interceptors are installed into the input and output layers to modulate the positions and the colors, and consequently the innovations are achieved on the geometric formation and color distribution of the pattern. Findings It has turned out that the precision of reconstruction is concerned with network scale, training epochs and color mode of the sample set. Four primary innovative effects including stripes, twisters, sandification and overprints have been qualified in terms of interceptors. Originality/value This study introduces ANN into textile pattern generation and provides a novel way to perform digital innovation of textile patterns.

Remote sensing image classification plays an important role in a wide range of applications and has caused widely concerns. During the last few years, great efforts have been made to develop a number of scene classification methods for remote sensing images. However, the existing remote sensing image classification methods do not perform satisfactorily in dealing with multi-class classification problems and rely heavily on the quality of data sets. These disadvantages seriously restrict the application of remote sensing image, including industrial research, analysis and calculation of land use and land coverage. To this end, this paper proposes a remote sensing image classification algorithm based on the sparse regularized feature learning method. Specifically, after constructing bag of features by using speeded up robust features extraction algorithm, direct sparsity optimization-based feature selection method is applied for selecting discriminative features, which is used for constructing support vector machine classifier model. The proposed algorithm has been evaluated and compared with other advanced feature selection methods on four public remote sensing image data sets. The experimental results demonstrate the effectiveness of our proposed image classification algorithm, which has been successfully applied to remote sensing image classification tasks.

This brief presents a modified radix-4 fast Fourier transform (FFT) signal flow graph, whose input and output both are in natural order. Compared with the conventional radix-4 signal flow graph, it does not buffer the result of the last stage or execute the bit-reverse operation to generate the result, but generates the result directly in the last stage. Thus, the number of iterations is reduced by one. In order to realize the proposed memory-based FFT processor by using the modified radix-4 FFT signal flow graph, a conflict-free strategy and corresponding memory-addressing scheme is proposed. At last, the hardware implementation for the proposed FFT processor is proposed. Through the adoption of this method, FFT processor of arbitrary point conforming to the radix-4 algorithm can be implemented. Compared with the previous memory-based FFT processors, the proposed FFT processor has less processing time under similar or lower resource consumption.

As for ultrasonic vibration assisted grinding (UVAG) of carbon/epoxy (C/E) composites, the grinding temperature is greatly influenced by their structural characteristics (such as epoxy resin content and fiber directional angle ( θ )). For revealing their relationship, C/E composite workpieces with various structural characteristics were designed and prepared; moreover, Fiber Bragg grating (FBG) sensors were embedded in each workpiece for measurement of the grinding temperature; in addition, various grinding parameters were set in UVAG experiments. Experimental results show that: 1). the grinding temperature is influenced very remarkably by the fiber directional angle of C/E composites and the grinding temperature along the direction of fibers is much higher than that reverse fiber direction; 2). the grinding temperature peaks under fiber directional angle ( θ = 90 ° ); 3). on the premise of meeting the performance of workpieces, the grinding temperature raises with the increase of epoxy resin content; 4). the change of grinding parameters has nothing to do with the relationship (the grinding temperature vs. the structural characteristics of C/E composites).

Metal halide-based perovskite nanocrystals, as promising materials in light-emitting diodes (LEDs), have recently attracted considerable attention for their efficient charge transport properties, high color purity, and tunable bandgap over the entire visible spectral range. However, the poor stability and high surface roughness of halide-based perovskites are preventing them from wide applications in lighting and displays. Here, we report a facile method to obtain efficient and stable green-emitting perovskite light-emitting diodes (PeLEDs) by treating the surface of a perovskite film with octylamine solution. The luminescence efficiency, color purity, and light-emitting device stability were confirmed to be improved by the analysis of the morphology of the perovskite thin film and the photoelectric properties of the ligand-managed PeLEDs. The EQE of green CsPbBr3 PeLEDs increased from 7.0% to 11.1% via the surface ligand management. Therefore, the studies of this work will be promising in improving the efficiency and stability of PeLEDs. Thus, we expect these results to facilitate the research of perovskite-based light-emitting diodes for the new generation of lighting and display technologies.

The self-assembled organic microspheres of (E)-3-(4-(dip-tolylamino)phenyl)-1-(4-fluoro-2-hydroxyphenyl)prop-2-en-1-one (DTPHP) are fabricated, which serve as active WGM resonators. In addition, a dispersion relationship between the group refractive index (ng) and wavelength (λ) is revealed to demonstrate the strong light–matter interaction inside the WGM microcavity with a maximum ng to be 7.7.

High permittivity materials continue to arouse considerable interest due to their applications in the field of high performance capacitors. However it is still a challenge to make material both with stable high permittivity and low dielectric loss. Here, the Sr1-3x/2CexTiO3 (SCT) ceramics are synthesized via solid-state reaction process and sintering in air. The sample (x = 0.01) exhibits a high permittivity of ∼7000 and low dielectric loss of ∼0.007 at room temperature and 1 kHz. Moreover, the dielectric properties are stable over a very broad temperature and frequency range. Further investigations reveal that the high permittivity is related to the defect chemistry caused by the trace Ce ions doping. The Ti3+ ions substitute the Ti4+ ions lead to the Ti-O octahedral off-center, which make a certain contribution to improve the permittivity. The low dielectric loss is owing to the fact that the defects are more likely to be in the form of defect clusters in the Ce doped SrTiO3 monophase solid solutions. The appropriate defect chemistry design suppresses the dielectric loss relaxation peak of Sr1-xCexTiO3 (x = 0.01) caused by the motion of oxygen vacancies.

The participation of demand side resources in the distributed trading market has become an important means for countries in the world to alleviate the pressure of supply and demand during peak hours. How to make full use of the time-varying price signals in the spot market and effectively tap the demand side response potential of customers has become the key issue of the key marketing strategy research for power sales companies. Firstly, this paper constructs distributed transaction models to clarify the transaction characteristics of both parties; Then, the cost model of adjustable load participating in distributed trading market is constructed with the objective of minimizing the cost of power consumption and the cost of satisfaction reduction caused by participating in demand response regulation, and the corresponding constraints are set; Finally, based on blockchain technology and smart contract system, the optimal strategy of adjustable load participating in distributed trading market is solved. Case simulation results show that the proposed strategy can effectively achieve the goal of load reduction on the grid side, and stimulate the willingness of users to participate in demand response, which has a certain practical significance.

There are many potential information of user behavior hidden in client big data, which is necessary to accurately position the users' electricity consumption behavior. The power consumption behavior of the users in different industries has certain patterns. If the different intrinsic characteristics of the users in different industries are ignored, the energy consumption prediction will produce errors. By deeply mining the accurate information in client big data, it can effectively analyze the users' electricity consumption behavior, make the user characteristics more representative, greatly improve the utilization efficiency of equipment, and reduce energy consumption. Therefore, in order to reduce the impact of the uncertainty of users' behavior on energy consumption prediction of various industries, this paper models the energy consumption of three industries based on the analysis of users' behavior in the construction industry, transportation industry and communication industry, and verifies the accuracy and effectiveness of the model through case simulation, aiming to provide basis and reference for the next planning of various industries suggestions.

Many prediction tasks of real-world applications need to model multi-order feature interactions in user's event sequence for better detection performance. However, existing popular solutions usually suffer two key issues: 1) only focusing on feature interactions and failing to capture the sequence influence; 2) only focusing on sequence information, but ignoring internal feature relations of each event, thus failing to extract a better event representation. In this paper, we consider a two-level structure for capturing the hierarchical information over user's event sequence: 1) learning effective feature interactions based event representation; 2) modeling the sequence representation of user's historical events. Experimental results on both industrial and public datasets clearly demonstrate that our model achieves significantly better performance compared with state-of-the-art baselines., Comment: Accepted by SIGIR2020

The microstructural evolution and mechanical behavior of cast duplex stainless steels (CDSSs) at 400 °C for different thermal aging times were investigated by transmission electron microscope (TEM) and small punch test (SPT). The results showed that the spinodal decomposition in ferrite was the main reason for the decrease in toughness, and G-phase did not play an important role in the embrittlement process. The change of membrane stretching zone (Wm) played an important role in the SPT load-displacement curve before and after thermal aging. During the deformation process of Wm in the SPT, for thermal aging for 10,000 h, some completely curved slip bands were generated inside the ferrite phase, which had no contact with the δ/γ phase interface and belonged to the slip bands produced by the independent deformation of ferrite. The combined effect of the curved slip bands and stress concentration led to the initiation of obvious micro-cracks at the δ/γ phase interface. The micro-cracks propagated along the ferrite phase curved slip bands, and eventually penetrated the entire hardened ferrite phase.

Summary Promoting solar fuels as a viable alternative to hydrocarbons calls for technologies that couple efficiency, durability, and low cost. In this work we elucidate how hybrid organic-inorganic systems employing hybrid photocathodes (HPC) and perovskite solar cells (PSC) could eventually match these needs, enabling sustainable and clean hydrogen production. First, we demonstrate a system comprising an HPC, a PSC, and a Ru-based oxygen evolution catalyst reaching a solar-to-hydrogen (STH) efficiency above 2%. Moving from this experimental result, we elaborate a perspective for this technology by adapting the existing models to the specific case of an HPC-PSC tandem. We found two very promising scenarios: one with a 10% STH efficiency, achievable using the currently available semiconducting polymers and the widely used methylammonium lead iodide (MAPI) PSC, and the other one with a 20% STH efficiency, requiring dedicated development for water-splitting applications of recently reported high-performing organic semiconductors and narrow band-gap perovskites., Graphical abstract, Highlights • 2% STH efficiency with a hybrid photocathode/perovskite solar cell tandem system • Multi-variable optimization tool used to find the optimal parameters to maximize STH • Optimized photocathode parameters are found in order to reach the 10% STH goal • Long-term scenario with 20% STH is predicted for hybrid organic tandem systems, Chemistry; Chemical engineering; Catalysis; Electrochemistry

As a general interface for chip system testing and on-chip debugging, JTAG is facing serious security threats. By analyzing the typical JTAG attack model and security protection measures, this paper designs a secure JTAG debugging model based on Schnorr identity authentication protocol, and takes RISCV as an example to build a set of SoC prototype system to complete functional verification. Experiments show that this secure JTAG debugging model has high security, flexible implementation, and good portability. It can meet the JTAG security protection requirements in various application scenarios. The maximum clock frequency can reach 833MHZ, while the hardware overhead is only 47.93KGate.

In this paper, a cooling scheme and the corresponding thermal design method is proposed for high power high frequency transformer, which is used in power electronic transformer device for railway traction applications. Particularly, to address the overheating problem resulting from dimensional restriction and electrical insulation in railway applications, the cooling scheme based on actively cooled system with R245fa refrigerants is further enhanced by 2-phase flow cooling. The mathematic model of transformer copper and iron loss is first introduced. Subsequently, the required cooling area of transformer core is quantitatively calculated using thermal network method and the total pressure loss and heat transfer in two-phase flow is determined accordingly. Finally, the proposed thermal design method and corresponding cooling scheme are verified through the experiment on a 5.5kHz 140kVA transformer.

In order to solve the problem of low bandwidth and low real-time performance in the existing train communication network, a novel topology optimization scheme is presented. The data traffic between train subnets would be reduced through the topology optimization. To obtain the global optimal solution, an improved adaptive genetic algorithm is presented. In this algorithm, the sigmoid function was used in the crossover probability and the mutation probability. At the beginning of the population evolution, the probability could stay at high level to obtain enough individuals, and in the later the probability could reduce rapidly to guaranteed convergence of fitness function. An example analysis shows that the optimization scheme based on the algorithm can balance the data traffic within each subnet and reduce the data traffic between subnets, which can improve real-time performance of train communication network significantly.

So far, the combination of methylammonium bromide/methylammonium chloride (MABr/MACl) or methylammonium iodide (MAI)/MACl is the most frequently used additives to stabilize formamidinium lead iodide (FAPbI3 ) fabricated by the sequential deposition method. However, the enlarged bandgap due to the addition of bromide and the ambiguous functions of these additives in lead iodide (PbI2 ) transformation are still worth considering. Herein, the roles of MACl in sequentially deposited Br-free FA-based perovskites are systematically investigated. It is found that MACl can finely regulate the PbI2 /FAI reaction, tune the phase transition at room temperature, and adjust intermediate-related perovskite crystallization and decomposition during thermal annealing. Compared to FAPbI3 , the perovskite with MACl exhibits larger grain, longer carrier lifetime, and reduced trap density. The resultant solar cell therefore achieves a champion power conversion efficiency (PCE) of 23.1% under reverse scan with a stabilized power output of 23.0%. In addition, it shows much improved photostability under 100 mW cm-2 white illumination (xenon lamp) in nitrogen atmosphere without encapsulation.

The rational design and the fine synthesis of organic heterostructures (OHSs) are the key steps toward integrated organic optoelectronics. Herein we have demonstrated a self-assembly approach of combining a molecular-level heterostructure with a structural-level heterostructure and regulating the noncovalent intermolecular interactions for the precise construction of OHSs: a vertical type of anthracene-TCNB heterostructure and a horizontal type of benzopyrene-TCNB heterostructure. The excellent structural compatibility and the low lattice mismatch rate of ∼5.8% between single-component microplates and cocrystal microwires allow anthracene and benzopyrene molecules to grow epitaxially on the cocrystal. Significantly, integrating the multicolor emission and the distinctive dimensional-dependent photon transportation properties of low-dimensional micro/nanostructures, the multicolor optical outputs are achieved via modulating the active/passive optical waveguides in OHSs. Our work exhibits the utilization of the multilevel heterostructure strategy, which boosts the rational design of OHSs for organic photonics.

The deformation behavior and fracture mechanism of cast duplex stainless steel tubular specimens under different tensile stages were investigated through experimental and numerical evaluation. The results showed that the axial stress was redistributed due to the necking of the tubular specimen, the axial stress near the internal wall was larger than those near the external wall, and its maximum axial stress was distributed between the internal wall and the center of the wall thickness. Microcracks and voids were initiated under the maximum shear stress along the δ/γ phase interface and propagated to the ferrite interior. The voids were connected and merged into the main crack through the propagation of the microcracks. Moreover, the main crack first propagated to the internal wall and then rapidly propagated to the external wall. The fracture morphology can be divided into three types: shear lip zones that can be found on both the internal and external walls, and shear lip zones that can be found on either only the internal wall or the external wall.

This paper presents a new binary image lossless compression algorithm for Digital Light Processing (DLP) printers. Considering the continuity of 3D model slicing images and the features of the pixels in slicing images, this algorithm is characterized by delta-encoding and two-stage compression to facilitate image compression, which is simple to implement. Compared with other algorithms used for image compression, the proposed one achieves the best performance when the same test cases are treated.

Wireline formation testing has evolved from discrete pressure measurements, introduced in the 1950s to measuring pressure gradients and fluid contacts since the 1970s. Technology introduced in the late 1980s and onwards added interval pressure transient testing, focused sampling, and downhole fluid analysis. Thirty years later, this paper shows data examples of a recently developed formation testing platform in a wide range of environments, and applications, that change how we plan, acquire, and use formation testing. The dual-flow-line architecture of the formation testing platform is designed to systematically address shortcomings of legacy technology, enabling focused sampling in the tightest conventional formations, as well as transient testing in high mobility environments. Specialized pre-job planning software evaluates conveyance options to minimize friction and borehole contact, estimates the available flow rate, compares cleanup performance of the different inlets, and simulates transient testing responses. During the operation, the platform uses hardware embedded automation algorithms that execute routine tasks in a consistent and highly efficient manner, leaving more time for the user to focus on data quality and value of the measurements. Case studies from Mexico, Norway, and the US demonstrate specific improvements in capability and performance. Field data from Mexico shows focused sampling of gas condensate from a heterogeneous submillidarcy carbonate formation in an HP/HT well drilled with oil-based mud. Controlled downhole decompression of crude oil in the flowline at a sampling station in Norway enabled real-time measurement of its bubblepoint pressure to within 6 psi of that measured in the laboratory. Another case study integrates accurate relative asphaltene gradients into an existing reservoir fluid study to prove reservoir connectivity across a large lateral distance in a producing field. Application of the dual packer subsystem demonstrates inflation within four minutes and pure oil samples within 90 minutes on station in a 1.5-md/cp fractured basement formation. The fine pump control at a low rate enabled sampling just below reservoir pressure in Alaska and a case from the Gulf of Mexico demonstrates the real-time impact of fluid properties on the understanding of reservoir architecture and completion design. The presented examples highlight the impact of downhole automation, define the new operating envelope for formation testing in the most challenging environments, and highlight how the technology development leads to decision making on a broad reservoir scale by providing contextual answers rather than an accumulation of facts and figures.

Antireflection (AR) film is a widely used technology to enhance the performance of photovoltaic devices that require transparent electrodes in the photovoltaic industry. At present, several AR films including monolayer MgF2 or multilayered composite films, textured polydimethylsiloxane (PDMS) and porous SiO2 have been successfully applied due to their excellent properties. Nevertheless, all of the above-mentioned AR films have some minor drawbacks to overcome, for instance, the cost or thermal durability. Herein, we report a cost-effective and low-temperature method to fabricate a mesoporous aluminum oxide (meso-Al2O3) layer as the AR coating with high thermal durability, which will meet the fabrication condition of various photovoltaic devices. Briefly, the process begins at magnetron sputtering a compact Al2O3 film, which shows no AR effect, followed by a hot water treatment at 80 °C to turn the compact film into a mesoporous film with graded-index and AR effect. The application of meso-Al2O3 AR film enhances the maximum transmittance of our laboratory-used fluorine-doped tin oxide (FTO) from 84% to 89%, which is in good agreement with our theoretical simulation named graded-index approximation. Taking perovskite solar cells (PSCs) as an example, planar PSCs with meso-Al2O3 AR film deliver excellent photon conversion efficiency of 21.5%, which is higher than that of cells without meso-Al2O3 AR film (20.9%).

Anisotropic organic molecular construction and packing are crucial for the optoelectronic properties of organic crystals. Two-dimensional (2D) organic crystals with regular morphology and good photon confinement are potentially suitable for a chip-scale planar photonics system. Herein, through the bottom-up process, 2D halogen-bonded DPEpe-F4 DIB cocrystals were fabricated that exhibit an asymmetric optical waveguide with the optical-loss coefficients of RBackward =0.0346 dB μm-1 and RForward =0.0894 dB μm-1 along the [010] crystal direction, which can be attributed to the unidirectional total internal reflection caused by the anisotropic molecular packing mode. Based on this crystal direction-oriented asymmetric photon transport, these as-prepared 2D cocrystals have been demonstrated as a microscale optical logic gate with multiple input/out channels, which will offer potential applications as the 2D optical component for the integrated organic photonics.

Homo-/heterostructures are of essential importance for the multiple input/output and the wavelength division multiplexing system in optoelectronic circuits. However, the widely used preparation met...

A set of conjugated polymers PCzDPTx with carbazole/diphenylamine as backbone and 9H-thioxanthen-9-one-10,10-dioxide as the pendant, where DPT is 2-(4-(diphenylamino)-phenyl)-9H-thioxanthen-9-one-10,10-dioxide, and x = 1, 5, 10, 25 and 50, respectively, and two alternating copolymers PTCz and PTD with the backbone consisting of the acceptor unit 9H-thioxanthen-9-one-10,10-dioxide and the donor unit carbazole and diphenylamine groups have been respectively synthesized by Pd-catalyzed Suzuki coupling polycondensation. These polymers in films show long wavelength emissions of 573–629 nm with thermally activated delayed fluorescence (TADF) characteristics, confirmed by theory calculations and their transient PL decay spectra. Various organic light-emitting diodes (OLEDs) using the TADF polymers as emitters were fabricated by solution processing. The doped OLEDs based on the polymers PTD and PCzDPT50 with the 50% molar content of the DPT unit as the emitters produce the saturated red electroluminescence with Commission Internationale de l'Eclairage (CIE) coordinates (0.64, 0.36) and (0.63, 0.37), respectively. For the first time, a TADF polymer based sensitizer was utilized to further improve the electroluminescent performances of the TADF polymers with low quantum yields, e.g., at the maximum, 3.8-fold increase in the brightness and 1.8-fold increase in the external quantum efficiency were simultaneously demonstrated.

The extensive use of graphite materials in the high temperature gas cooled reactor provides the inherent safety of the HTGR. However, the motion and deposition of the graphite particles produced by these materials have an important influence on the normal HTGR operation. The present research experimentally investigates the thermophoretic deposition of graphite dust in an HTGR in a straight pipe for various Reynolds numbers and inlet temperatures. A temperature gradient was produced by a high temperature aerosol flowing inside a tube with cooling water flowing in the annulus. The temperature distributions were predicted by numerical simulations with good agreement with measurements. The aerosol decreased dramatically in the first part of the tube and then more slowly in the latter part. The particle diameters ranged from 500 to 3000 nm with most of the particle sizes concentrated near 1600 nm. The deposition experiments showed that the deposition efficiency increases with increasing inlet temperature because of the larger temperature gradient and stronger thermophoretic force pushing the particles toward the surface. The particle deposition decreased with increasing Reynolds number due to the shorter particle residence times in the pipe. The results indicated that the thermophoretic deposition efficiency of irregular graphite particles is smaller than the predicted result by the formula of Byers and Calvert (1969) which is based on the hypothesis of sphere particles.

In allusion to the challenging issue of identifying fabric materials by frictional sounds, this study endeavors to prove the possibility of classifying fabric friction sounds into their material categories using discriminators built upon the Haar features. A total of 32 pieces of fabric falling into four material categories including cotton, wool, silk, and flax are put through a specialized apparatus to collect frictional sound signals. The Haar features on every scale and position of the acquired signal are extracted to establish a feature space. For each point in the feature space, a discriminator is built to approve all positive samples of a certain category and deny as many negative samples as possible. To relieve the heavy burden produced by the huge number of discriminators, progressive selection is performed on the discriminators to form a queue in which a discriminator is liable to fix some errors of the former. The outcome is a much-reduced version of the unordered discriminators with the same discriminability. The improved Haar feature is also investigated and is found to be capable of reducing the size of the discrimination queue, thus further improving the efficiency of the mechanism. It is also revealed that additional samples involved can help achieve a perfect accuracy. The discrimination mechanism advanced by this effort can provide a basis for identifying fabric materials by frictional sounds.

The hydropower group is a kind of weak AC system while hydropower asynchronous interconnected with main network through VSC-HVDC (Voltage Source Converter based High Voltage Direct Current). Thus, VSC-HVDC should be taken part into the system voltage and frequency control, which can enhance the transient stability of power grid while reduce the conventional control costs at the same time. The transfer function of turbine governor is introduced to expound the principle of hydraulic turbine unit participating in DC power support. Different kinds of DC power modulation have been compared which show the difference of power angle recovery after fault between VSC-HVDC and LCC-HVDC (Line Commutated Converter based High Voltage Direct Current) power support, thus the modulation priority of different kinds of DC in the emergency control should be taken into consideration. The DC power support quantity calculation method after fault is proposed in this paper. The emergency coordination control strategy can be formulated by considering with both priority and DC power support quantity under different fault.