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This letter presents a new class of High-overtone Bulk Acoustic Resonators (HBARs) with only top electrodes but excellent performance using lithium niobate (LN) thin films on conductive silicon carbide (SiC). The 4-inch single-crystalline lithium niobate thin film on conductive SiC (LNCSiC) substrate was prepared by ion-cutting process. Since the conductive SiC serves as both the resonant cavity and the floating electrode, the HBARs based on LNCSiC with only top electrodes were designed and fabricated. The devices show a wide frequency response span exceeding 2.0 GHz, a frequency spacing of 10 MHz, an excellent f $\cdot $ Q $_{\textit {LAKIN}}$ product of ${9.6}\times {10} ^{{13}}$ Hz ( f $\cdot $ Bode-Q of ${1.1}\times {10} ^{{14}}$ Hz), and a low temperature coefficient of frequency (TCF) of −18.9 ppm/°C. The frequency response shift of the proposed HBAR can be achieved by just adjusting the in-plane orientation of the top electrodes. Additionally, a multi-band filter was numerically synthesized based on the proposed HBARs, showing a spectral spacing of 10 MHz and a passband span of more than 2.0 GHz. Upon further optimizations, the proposed HBARs with a wide frequency response, a high- f $\cdot $ Q , and a low-TCF will be very promising for radio-frequency applications.

A semiactive seat suspension control method is proposed in this study and applied to attenuate the vibration of the commercial truck seat for enhancing its ride comfort. The semiactive seat suspension system with a magnetorheological damper behaves with undesirable nonlinear properties. The proposed controller is a typical nonlinear controller, which takes the ideal sky-hook controller as the reference model and forces the tracking error vector. The controller has achieved great performance of attenuating vibration and is robust to parameter uncertainties and external disturbances. The relaxation oscillation phenomenon and convergence were also analyzed by the contribution of the phase portrait. As the phase portrait depicted, the sky-hook controller, a weakly nonlinear system, could be approximated by the equivalent linear approximate model. However, the proposed controller, the sky-hook sliding mode controller, is a strongly nonlinear system, which could not be linearized by the regular perturbation theory, and the criterion is given by the phase portrait. The experiment results showed good agreement with the simulation results, and some other matters encountered were also analyzed in the process of application.

Single-crystalline halide perovskites with regular morphology are of great significance for laser applications because they can be used to fabricate a natural whispering-gallery-mode resonator. Although enormous efforts have been put to synthesize single-crystalline perovskites, controlling the lateral size and thickness of the crystal, particularly at the nanoscale, is still challenging. Here, we report a facile and high-throughput strategy to selectively one-step create micro/nanoscale size-controlled all-inorganic perovskite single-crystal arrays by surface-tension-confined evaporative assembly. Our method can be used to easily tune the single crystal size and selectively position the single crystal, with versatility in fabricating perovskite single-crystal arrays in a wafer scale. When the patterned size increases from 2 to 25 μm, the width of the CsPbClBr

Objective: Myocardial infarction (MI) is acknowledged as a major cause of heart disease related death in the world. This study aims to explore the function and mechanism of miR-17-5p-induced STAT3 in myocardial remodeling after MI.Methods: MI mice were infected by lentivirus antago-miR-17-5p vector. The expression of miR-17-5p in myocardial tissues was detected. The levels of STAT3 and specific markers of autophagy LC3-II/LC3-I, Beclin-1 and p62 were measured. Myocardial remodeling and scar size were assessed and cell apoptosis was determined. The binding of miR-17-5p and STAT3 was analyzed. The functions of miR-17-5p and STAT3 in autophagy and myocardial remodeling after MI were confirmed by functional rescue experiment after injecting STAT3 inhibitor S31-20.Results: Decreased fractional shortening, increased left ventricular systolic diameter and ventricular filling velocity were detected in MI mice. High expression of miR-17-5p was found in myocardial tissues after MI. The inhibition of miR-17-5p expression led to reduction of fibrosis of myocardial tissues, scarring, cardiomyocyte apoptosis, and expressions of LC3-II/LC3-I and Beclin-1, and increased p62 expression after MI. miR-17-5p targeted STAT3 and negatively regulated its expression. Inhibition of STAT3 level reversed the improving effect of antago-miR-17-5p on MI.Conclusion: Inhibition of miR-17-5p can inhibit myocardial autophagy through targeting STAT3, and then inhibit myocardial remodeling, thereby protecting myocardium after MI.

Background: Breast cancer has remained the most common malignancy in women over the past two decades. As lifestyle and living environments have changed, alterations to the disease spectrum have inevitably occurred in this time. As molecular profiling has become a routine diagnostic and objective indicator of breast cancer etiology, we analyzed changes in gene expression in breast cancer populations over two decades using The Cancer Genome Atlas (TCGA). Methods: We performed Heatmap and Venn diagram analyses to identify constantly up- and down-regulated genes in this cohort. We used Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses to visualize associated functional pathways. Results: We determined that three oncogenes, PD-L2, ETV5, and MTOR and 113 long intergenic non-coding RNAs (lincRNAs) were constantly up-regulated, whereas two oncogenes, BCR and GTF2I, one tumor suppression gene (TSG) MEN1, and 30 lincRNAs were constantly down-regulated. Up-regulated genes were enriched in “focal adhesion” and “PI3K-Akt signaling” pathways, et al, and down-regulated genes were significantly enriched in “metabolic pathways” and “viral myocarditis”. Eight up-regulated genes exhibited doubled or higher expression, and the expression of three down-regulated genes was halved or lowered and correlated with long-term survival. Conclusions: In this study, we determined that genes and molecular pathways are constantly changing, importantly, some altered genes were associated with prognostics and are potential therapeutic targets, suggesting molecular typing technologies must keep pace with this dynamic situation.

In this work, a simple structure of ultra-thin LiTaO 3 (LT) film on extremely high-resistance sapphire substrate (LTOS) was proposed. The PSC effect has little effect on the effective resistivity (peff) of the LT /sapphire interface in LTOS since the resistivity of sapphire is greater than 1014 Ω. cm (lack of sufficient free carriers), therefore the RF loss in LTOS substrate is limited. The 4-inch LTOS substrate was prepared by ion-cutting process, and high-Q resonators and a low insertion loss (IL) filter were demonstrated on the LTOS substrate. The resonator exhibits an extracted k2 of 6.62 % and a maximum Bode-Q (Qmax) of 2100, resulting in a FoM (k2×Qmax) of 139. The filter with a center frequency of 2231 MHz features a minimum IL of 0.61 dB and a 3-dB fractional bandwidth (FBW) of 3.6%. The SAW devices on LTOS substrate show a great potential for applications in RF wireless communications.

In this work, the phase velocity (V p ) and the electromechanical coupling factors (k t 2) of SH0 modes excited in X-cut LiNbO 3 (LN) films were studied by finite element analysis, and both of them show strong dispersion when LN films are bonded to foreign substrates. In particular, the V p of the SH0 mode in LiNbO 3 -on-SiC (LNOSiC) substrate can exceed 1.5 times the value in LN plate, so as the operating frequency. 4-inch LNOSiC substrate was fabricated by ion-cutting process. A group of SH0 mode resonators on the novel LNOSiC substrate were demonstrated, so as the ladder-type filter. Since part of the acoustic energy of the SH0 mode penetrates into the high-velocity SiC supporting substrate, the fabricated resonator exhibits a phase velocity of exceeding 5000 m/s. The ladder-type filter composed of the SH0 mode resonators with increased velocity shows a center frequency (f c ) of 3.93 GHz, an insertion loss (IL) of 2.05 dB and a 3-dB fractional bandwidth (FBW) of 14.2%. The acoustic devices on LNOSiC heterogeneous substrate are very promising for high frequency and wideband 5G front-ends.

In this work, a novel heterogeneous substrate of lithium tantalate thin film on silicon carbide (LiTaO 3 -on-SiC, LTOSiC) was proposed and prepared. Since the SiC features an extremely-high phase velocity, a low acoustic loss and a small thermal expansion coefficient (CTE), surface acoustic wave devices with high frequency, low loss and low TCF were achieved on the LTOSiC substrate. The fabricated shear horizontal surface acoustic wave (SH-SAW) resonator shows a maximum Bode-Q (Bode-Qmax) of 2235 and a low TCF of -9.4 ppm/K at 1.90 GHz, while the longitudinal leaky surface acoustic wave (LLSAW) resonator shows a high Bode-Qmax of 1180 and an improved TCF of -24.7 ppm/K at 4.40 GHz. The ladder-type filter composed of SH-SAW resonators was also demonstrated, showing a center frequency (fc) of 3.03 GHz, an insertion loss (IL) of 0.9 dB and a 3-dB bandwidth of 101 MHz. The TCFs at - 3 dB attenuation of the lower and higher frequency side of passband are -13.8 and -15.8 ppm/K, respectively. The acoustic devices on LTOSiC substrate possess the prospect of commercial applications in 5G era.

In this work, we introduce a novel architecture for monolithic integrated multiband filters based on lithium niobate on insulator (LNOI) platform. The advantages of the crystal cut of Y124° are introduced compared to Z-cut. Three typical acoustic modes are excited simultaneously in different in-plane directions of a 400 nm Y124°-cut LiNbO 3 thin film. Combining with the buried electrode structure, the multiband filters with a wide operating frequency range from L band to C band, and a wide fractional bandwidth (FBW) range from 3.5% to 26% are achieved. The proposed structure provides an attractive solution for monolithic integration of filters.

The level of hardware or information security can be increased by applying physical unclonable functions (PUFs), which have a high complexity and unique nonreplicability and are based on random physical patterns generated by nature, to anticounterfeiting and encryption technologies. The preparation of PUFs should be as simple and convenient as possible, while maintaining the high complexity and stability of PUFs to ensure high reliability in use. In this study, an all-inorganic perovskite single-crystal array with a controllable morphology and a random size was prepared by a one-step recrystallization method in a solvent atmosphere to generate all-photonic cryptographic primitives. The nondeterministic size of the perovskite nanorods mainly arises from crystal growth in an indeterminate direction, producing a high entropy for the system. The cavity-size-dependent lasing emission behavior of perovskite single crystals was investigated as a preliminary exploration of the generation of all-photonic cryptographic primitives. The lasing-mode number was positively correlated with the length of the perovskite nanorods. Therefore, the prepared perovskite nanorod array with random sizes can be transformed into a quaternary cryptographic key array following encoding rules based on the lasing-mode number. Superior lasing stability was observed for the all-inorganic perovskite under continuous excitation, demonstrating the high reliability of this system.

The high-efficiency photocarrier collection at the interfaces plays an important role in improving the performance of perovskite solar cells (PSCs) because the photocarrier effective diffusion leng...

This paper presents a novel approach for automatic, rapid and efficient micro-droplet mixing on ‘open-surface’ droplet-based microfluidics system via magnetic actuation. A two-step micro-fabrication process was employed to decorate the magnetically functionalized polydimethylsiloxane (PDMS) membrane with micro-pillar arrays (MPA) to reduce the adhesion on resident droplets. Droplet manipulation relies on the localized deformation of the elastic membrane under external magnetic fields, thus relieving the additives of magnetic components to the droplets that is commonly required in conventional magnetism-based actuation. Via integration with peripheral computer-based regulator, swift droplet mixing is realized via controlling the coalescent droplets back and forth to generate internal fluid circulations for enhanced mass transfer within the droplet. The comparison of mixing performance between the coalesce-and-stop and back-and-forth mode was systematically performed, which verifies that the back-and-forth actuation of the droplets can obviously improve the mixing efficiency, and typically a higher driving frequency on the droplet renders a shorter mixing duration. With driving frequency of 2.5 cycles/s, the mixing homogeneity can reach 80% within 0.6 s and reach 90% within 1.5 s. Also, it has been experimentally demonstrated that the proposed system can accelerate the dilution under various volume ratios, including 1:2, 1:5, and 1:10. Finally, we demonstrated that the platform can be used to dynamically manipulate the droplets, allowing the de-pinning effect for molecular concentrating and obvious detection sensitivity enhancement in terms of Surface-Enhanced Raman Scattering (SERS). Owing to the superiorities including programmable efficient mixing and parallel scalability, the study herein offers insights for exploiting cost-effective and versatile microfluidics platform for future application in biological analysis, chemical micro-reactions, and trace molecule detections.

SnO2 quantum dots (QDs) ended with chlorine ions are introduced at the interface of spin-coated TiO2 electron selective layer (ESL)/perovskite to fill the pinholes in the layer and passivate the trapping defects. As a result of the increased interface electron collection and reduced bulk recombination, the planar perovskite solar cell with the QDs modified ESL gives the large power conversion efficiency enhancement from 14.9% to 17.3% and greatly improved stability under the continuous light irradiation.

Parallel manipulators have the advantages of high stiffness and low inertia compared to serial mechanisms. Based on the Steward-Gough platform architecture, a lot of 6-DOF mechanical devices have been proposed. The 6-DOF parallel manipulators suffer from a small workspace, complex mechanical design, and difficult motion generation and control due to their complex kinematic analysis. To overcome these shortcomings, the limited-DOF manipulator, which has fewer than 6 DOFs, can be found in many production lines. It is clear today that most attention has been paid to 3-DOF family among the limited-DOF parallel manipulators (Carretero, 2000). However, in many industrial situations, there is a need for equipment providing more than 3-DOFs. For example, for most pick-and-place applications in semiconductor manufacturing, at least 4 DOFs are required (3 translation to move the carried die from one point to the other, 1 rotation to adjust the orientation in its final location). A new family of 4-dof parallel manipulators called H4 that could be useful for high-speed pick-and-place applications is proposed by Pierrot and Company (Pierrot, 1999). The H4 manipulator offers 3 DOFs in translation and 1 DOF in rotation about a given axis. The H4 manipulator is useful for high-speed handling in robotics and milling in machinetool industry since it is a fully-parallel mechanism with no passive chain and able to provide high performance in terms of speed and acceleration. This chapter discusses the kinematic analysis of the H4 manipulator. In section 2, synthesis methods for designing H4 are presented, and various possible mechanical architectures of the parallel manipulator are exposed. Section 3 discusses the inverse and forward kinematics problem of H4. Section 4 deals with singularity analysis of H4 utilizing line geometry tools and screw theory. Section 5 concludes this chapter by providing the development tendency of the parallel manipulators.

Background: In the American Joint Commission on Cancer (AJCC) staging manual, ipsilateral supraclavicular lymph node metastases (ISLM) were defined as N3c, while contralateral supraclavicular and subclavian lymph node, contralateral internal mammary lymph node, contralateral axillary lymph node, and cervical lymph node as distant lymph nodes metastasis (DLM) were classified as M1, stage IV. Herein, we used the information recorded in the Surveillance, Epidemiology, and End Results (SEER) database to compare patients' overall survival with DLM, ISLM, and distant organ metastasis. Methods: A total of 376 patients with ISLM, 562 patients with DLM, 5,069 patients with IIIc stage breast cancer, and 7,540 patients with distant organ metastasis from the SEER database (2004-2016) were included in the present study. R package was used to perform the Kaplan–Meier survival analysis among these four groups, and propensity score weighting (PSW) was used to minimize the differences in clinicopathological characteristics among groupsResults: After PSW, the median survival of ISLM, DLM, IIIc stage, and distant organ metastasis was 42 months, 50 months, 55 months, and 31months, respectively. DLM achieved significantly better overall survival than distant organ metastasis (pConclusion: The prognosis of breast cancer patients with DLM was similar to ISLM and IIIc stage, but much better than that of patients with distant organ metastasis. Also, combined-modality therapy significantly improved long-term survival. Consequently, it seems more reasonable to classify DLM as IIIc category instead of M1.

COVID-19 is an acute respiratory disease caused by SARS-CoV-2, which has high transmissibility. People infected with SARS-CoV-2 can develop symptoms including cough, fever, pneumonia and other complications, which in severe cases could lead to death. In addition, a proportion of people infected with SARS-CoV-2 may be asymptomatic. At present, the primary diagnostic method for COVID-19 is reverse transcription-polymerase chain reaction (RT-PCR), which tests patient samples including nasopharyngeal swabs, sputum and other lower respiratory tract secretions. Other detection methods, e.g., isothermal nucleic acid amplification, CRISPR, immunochromatography, enzyme-linked immunosorbent assay (ELISA) and electrochemical sensors are also in use. As the current testing methods are mostly performed at central hospitals and third-party testing centres, the testing systems used mostly employ large, high-throughput, automated equipment. Given the current situation of the epidemic, point-of-care testing (POCT) is advantageous in terms of its ease of use, greater approachability on the user's end, more timely detection, and comparable accuracy and sensitivity, which could reduce the testing load on central hospitals. POCT is thus conducive to daily epidemic control and achieving early detection and treatment. This paper summarises the latest research advances in POCT-based SARS-CoV-2 detection methods, compares three categories of commercially available products, i.e., nucleic acid tests, immunoassays and novel sensors, and proposes the expectations for the development of POCT-based SARS-CoV-2 detection including greater accessibility, higher sensitivity and lower costs.

Three different novel dry-etching methods have been employed to fabricate nanophotonic devices upon a thin-film lithium niobate on insulator material platform. Different dry-etching processes and their advantages, drawbacks and applicable scenarios are systematically studied. Ultra-smooth etching surface with roughness of 0.46 nm (Rq), low-loss ridge waveguides with extracted propagation loss of 1.42 dB/cm, and microring resonators with high optical quality factors up to 1.4×105 are demonstrated using the optimized low-loss etching recipe. The low-loss etching technique lays a foundation for monolithic integration of passive optical components with quantum dots, on-chip broadband electro- optic modulators and wafer-scale lithium niobate integrated photonic circuits.

We demonstrate groups of surface wave (SH0 mode) and Lamb wave (S0 mode) acoustic devices on lithium niobate thin films on silicon carbide (LNOSiC) heterogeneous substrate. The 4-inch LNOSiC with an excellent thermal transport property is prepared by ion-cutting process. The fabricated acoustic resonators on the LNOSiC substrate show scalable resonances from 2.0 to 4.72 GHz, in which the SH0 (S0) mode resonator shows a $k_t^2$ of 24.1% (15.5%) and a maximum Bode-Q of 976 (577) at 2.54 (3.56) GHz. Moreover, the phase velocity (Vp) of the SH0 (S0) mode is greater than 5000 (6400) m/s, which is about 1.25 (1.6) times higher than that of the conventional SAWs, so as the operating frequency. The filter with a center frequency of 2.62 GHz, an insertion loss (IL) of 1.06 dB, and a 3-dB fractional bandwidth (FBW) of 12.6% (three times larger than that of the conventional SAWs) is also achieved. The acoustic devices on heterogeneous substrate are very promising for high frequency, wideband and high power 5G front-ends.

By studying the needs of targeted persons control, this paper constructs a targeted persons control system based on big data, realizes the structuration and standardization of multi-source heterogeneous data, and carries out big data analysis operations such as data association, personnel label analysis and knowledge map construction. On the basis of this system, this paper puts forward the application of targeted persons control based on big data, such as potential persons discovery, abnormal behavior identification, targeted persons tracking and crime situation analysis, providing development ideas for targeted persons control under the condition of big data.

Recently, wearable pressure sensors have attracted considerable interest in various fields such as healthcare monitoring, intelligent robots, etc. Although artificial structures or conductive materials have been well developed, the trade-off between sensitivity and linearity of pressure sensors is yet to be fully resolved by a traditional approach. Herein, from theoretical analysis to experimental design, we present the novel CPDMS/AgNWs double conductive layer (DCL) to synergistically optimize the sensitivity and linearity of piezoresistive pressure sensors. The facilely fabricated solid microdome array (SDA) is first employed as the elastomer to clarify the unrevealed working mechanism of DCL. Attributed to the synergistic effect of DCL, the DCL/SDA based sensor exhibits ultrahigh sensitivity (up to 3788.29 kPa-1) in an obviously broadened linearity range (0-6 kPa). We also demonstrated that the synergistic effect of DCL can be regulated with use of porous microdome array (PDA) to further optimize the sensing property. The linearity range can be improved up to 70 kPa while preserving the high sensitivity of 924.37 kPa-1 based on the interlocked PDA structure (IPDA), which is rarely reported in previous studies. The optimized sensitivity and linearity allow the competitive DCL/IPDA based sensor as a reliable platform to monitor kinds of physiological signals covering from low pressures (e.g., artery pulses), medium pressures (e.g., muscle expansions), to high pressures (e.g., body motions). We believe that the methodology along with the robust sensor can be of great potential for reliable healthcare monitoring and wearable electronic applications in the future.

Big data technology has become a hot research area and has expanded into the field of public safety. Public safety big data uses satellite data for large-scale detection, aerial photography for regional abnormality inspections, and ground sensor data for abnormal target positioning, which can realize public security events’ prediction and early warning. This paper focuses on the application of skyland big data in the border area, and builds a personnel management system, a vehicle management system, and a group activity early warning system in the border area, and builds a big data intelligent border area management system in the border area.

Big data technology has become a hot research area and has expanded into the field of public safety. Public safety big data uses satellite data for large-scale detection, aerial data for regional abnormality inspections, and ground sensor data for abnormal target positioning, which can realize the prediction and early warning of public safety events. This paper focuses on the application of big data in sky and ground in transportation hubs. It builds specific personnel management systems and crowd anomaly management systems in transportation hub areas, and develops big data system application demonstrations in transportation hubs to improve the level of public security incident handling in transportation hubs.

Big data technology has become a hot research area and has expanded into the field of public safety. Public safety big data uses satellite data for large-scale detection, aerial data for regional abnormality inspections, and ground sensor data for abnormal target positioning, which can realize the prediction and early warning of public safety events. This article focuses on the application of skyland big data in the chemical park, and builds the chemical industry park’s personnel management system, vehicle management system, perimeter management system, and fire accident warning system. The construction of a big data system application demonstration in the chemical park assists the construction of the park. Become a smart chemical park.

Summary In recent years, metal halide perovskite opens the new era of the photovoltaic field. The highest power conversion efficiency has exceeded 23%. Although most of reported perovskite solar cells (PSCs) were fabricated by solution methods, the vacuum thermal evaporation method has its unique advantages, such as easy controlling of film thickness, compatibility with tandem cell designs, flexibility to tune interfaces, free of solvent, etc. In this paper, we review the development and progress of the vacuum thermal evaporation method for fabricating PSCs.

Reconstructed transparent conductive films of fluorine doped tin oxide on glass substrates synthesized by electrochemical reduction followed by thermal oxidation were demonstrated to be effective in collecting photogenerated electrons in planar perovskite solar cells. Compared to the cells fabricated with the pristine film, the cell based on the reconstructed film shows an improved power conversion efficiency under forward scan from 9% to 15.1% and greatly weakened hysteresis behavior.

We describe a controllable sliding method for fabricating millions of isolated femto- to nanoliter-sized droplets with defined volume, geometry and position and a speed of up to 375 kHz. In this work, without using a superhydrophobic or superoleophobic surface, arrays of droplets are instantly formed on the patterned substrate by sliding a strip of liquid, including water, low-surface-tension organic solvents and solution, along the substrate. To precisely control the volume of the droplets, we systemically investigate the effects of the size of the wettable pattern, the viscosity of the liquid and sliding speed, which were found to vary independently to tune the height and volume of the droplets. Through this method, we successfully fabricated an oriented single metal–organic framework crystal array with control over their XY positioning on the surface, as characterized by microscopy and X-ray diffraction (XRD) techniques.

Wide-bandgap perovskites (WBPs) are attractive candidates for constructing tandem photovoltaic devices, but they are often much more prone to defect formation and other interfacial problems. Fixing these problems can boost the performance of WBP solar cells and is thus crucial for achieving a high overall energy conversion efficiency. Toward this end, we performed a systematic study on the construction of a 2D/3D heterostructure on the WBP surface to passivate the defects and to regulate the interfacial properties by varying the chain length of alkylammonium bromides in the 2D part. Hexanelammonium bromide (HABr) was found to be the champion in multiple respects. The optimized interfacial energy band structure and the reduced defect density with HABr allowed to achieve a remarkable 19.8% photovoltaic efficiency with a prominent open-circuit voltage (VOC) of 1.31 V. HABr also reduced interfacial capacitance by improving hole transport, substantially alleviating the hysteresis of the corresponding devices. Last but not least, the HABr-induced hydrophobicity in the 2D layer can not only block moisture, but also retard migration of the alkali cations from the perovskites across the interface, eventually endowing the WBP based devices with a superior moisture stability.

An ideal anti-counterfeiting label not only needs to be unclonable and accurate but also must consider cost and efficiency. But the traditional physical unclonable function (PUF) recognition technology must match all the images in a database one by one. The matching time increases with the number of samples. Here, a new kind of PUF anti-counterfeiting label is introduced with high modifiability, low reagent cost (2.1 × 10-4 USD), simple and fast authentication (overall time 12.17 s), high encoding capacity (2.1 × 10623 ), and its identification software. All inorganic perovskite nanocrystalline films with clonable micro-profile and unclonable micro-texture are prepared by laser engraving for lyophilic patterning, liquid strip sliding for high throughput droplet generation, and evaporative self-assembling for thin film deposition. A variety of crystal film profile shapes can be used as "specificator" for image recognition, and the verification time of recognition technology based on this divide-and-conquer strategy can be decreased by more than 20 times.

The zinc-oxide (ZnO) varistor is widely used to limit the overvoltage in the power systems, and its quality is closely related to the safety of the entire protected system. In this paper, accelerated aging experiments under different current levels were carried out on the ZnO varistors to study the harmonic characteristics of the leakage currents in the aging process. It is found that the proportions of higher order harmonics in leakage currents increase faster after several impulse tests and then a sudden decrease appears before the varistor fails, which is caused by the decrease of the varistor voltage. And based on this, a new criterion for the aging of the ZnO varistor is put forward.

Lightning is the main cause of transmission line failure, and it is important to improve the lightning protection level of the transmission line for the stability of the power system. Traditional solutions for the shielding failure of transmission lines is to use the electrical geometric model method. However, with the improvement of the voltage level, the physical size increases, and the calculation of lightning protection for ultrahigh-voltage dc lines has a greater difference with operating experience. Based on the Ningxia-Shandong dc transmission lines in China, this study utilised the lead development model to describe the flashover of insulators and the breakdown of the gaps. A comprehensive calculation method of shielding failure trip-out rate considering terrain, earth resistance and weather was proposed. The accuracy was much higher when compared with the traditional calculation and the result can be a reference for other similar calculation for dc lines.

In this paper, the application status and security problems of video surveillance system were analyzed. Solutions and design conceptions targeting the threats to terminal security were proposed, effects of solutions were described, and finally implementation and management methods of the solutions were discussed.

The insulation level of power apparatus is based on the protection level of overvoltage in power systems. Deeply suppressing the switching overvoltage of UHV systems will reduce the manufacturing cost and technical bottlenecks of UHV power apparatus. We studied the effects of multielements doping on the electrical properties of ZnO varistors co-doped with Al2O3, Ga2O3, and In2O3 Scanning electron microscopy, current–voltage testing, capacitance–voltage testing, and X-ray diffraction were performed. The results showed that the residual voltage ratio of sintered varistors decreased as the indium dopant concentration was increased. The samples with 0.03 mol % indium, 0.2 mol % aluminum, and 0.42 mol % gallium showed excellent overall performance, exhibiting a nonlinear coefficient of 61.2, a leakage current of 1.63 $\mu A /cm2$, a 1-mA residual voltage of 435 V/mm, and a residual voltage ratio of 1.52. These optimized properties will be of great utility in the manufacture of metal oxide arresters. The protective effects of this kind of novel surge arresters for lightning and switching overvoltage in UHV systems are analyzed. With the low residual voltage ZnO varistors applied to surge arresters will dramatically improving the protective effect of surge arresters, to realize the target to deeply suppress the lightning and switching overvoltages, and then reduce the insulation level and manufacturing bottleneck of UHV power apparatus.

Overvoltage and its protection are the key problems for power system. For ultra-high voltage system, switching overvoltage is the key factor of the insulation standard of power system. The suppression of the switching overvoltage in ultra-high voltage systems will reduce the manufacturing cost and technical bottlenecks of ultra-high voltage power apparatus. This paper studied the influence of multi-elements doping on the electrical performance of zinc oxide varistors. The easurment of scanning electron microscope, electric field-current density characteristics from small to large current region, capacitance-voltage were proceeded. The consequence of the experiments indicated that the residual voltage ratio decreased first and then increased. The zinc oxide varistor samples showed good properties with the composition of zero point four five mole fraction gallium and zero point zero three mole fraction indium. Showing a residual voltage ratio of one point five four, a nonlinear coefficient of sixty five, and a voltage gradient of four hundred and forty one volt per millimeter. Applying the high performance ZnO varistors to surge arresters will decrease the overvoltage level from 1.6-1.7p.u. to 1.2-1.3p.u., to realize the target to deeply suppress the switching overvoltage. This will further reduce the insulation level and manufacturing bottleneck of UHV power apparatus. This study is of great significance to promote the protective effect of the equipment assembled by zinc oxide varistor and the stabilization of the power system.

Most of the existing calibration methods for binocular stereo vision sensor (BSVS) depend on high-accuracy target with feature points that are difficult to manufacture and costly. In complex light conditions, optical filters are used for BSVS, but they affect imaging quality. Hence, the use of a high-accuracy target with certain-sized feature points for calibration is not feasible under such complex conditions. To solve these problems, a calibration method based on unknown-sized elliptical stripe images is proposed. With known intrinsic parameters, the proposed method adopts the elliptical stripes located on the parallel planes as a medium to calibrate BSVS online. In comparison with the common calibration methods, the proposed method avoids utilizing high-accuracy target with certain-sized feature points. Therefore, the proposed method is not only easy to implement but is a realistic method for the calibration of BSVS with optical filter. Changing the size of elliptical curves projected on the target solves the difficulty of applying the proposed method in different fields of view and distances. Simulative and physical experiments are conducted to validate the efficiency of the proposed method. When the field of view is approximately 400 mm × 300 mm, the proposed method can reach a calibration accuracy of 0.03 mm, which is comparable with that of Zhang’s method.

Speckle reduction remains a critical issue for ultrasound image processing and analysis. The nonlocal means (NLM) filter has recently attached much attention due to its competitive despeckling performance. However, the existing NLM methods usually determine the similarity between two patches by directly utilizing the gray-level information of the noisy image, which renders it difficult to represent the structural similarity of ultrasound images effectively. To address this problem, the NLM method based on the simple deep learning baseline named PCANet is proposed by introducing the intrinsic features of image patches extracted by this network rather than the pixel intensities into the pixel similarity computation. In this approach, the improved two-stage PCANet is proposed by using Parametric Rectified Linear Unit (PReLU) activation function instead of the binary hashing and block histograms in the original PCANet. This model is firstly trained on the ultrasound database to learn the convolution kernels. Then, the trained PCANet is utilized to extract the intrinsic features from the image patches in the pre-denoised version of the noisy image to be despeckled. These obtained features are concatenated together to determine the structural similarity between image patches in the NLM method, based on which the weighted mean of all pixels in a search window is computed to produce the final despeckled image. Extensive experiments have been conducted on a variety of images to demonstrate the superiority of the proposed method over several well-known despeckling algorithm and the PCANet based NLM method using ReLU function and sigmoid function. Visual inspection indicates that the proposed method outperforms the compared methods in reducing speckle noise and preserving image details. The quantitative comparisons show that among all the evaluated methods, our method produces the best structural similarity index metrics (SSIM) values for the synthetic image, as well as the highest equivalent number of looks (ENL) value for the simulated image and the clinical ultrasound images.

This paper studies the feasibility of segmenting large power system interconnections with AC link using energy storage technology, similar to the DC link, for improving the system dynamic stability. Firstly, the segmentation validity of the AC interconnected power system using energy storage technology is proved in terms of theoretical analysis, and then a simple and effective control strategy is proposed. Moreover, the influences of the energy storage device location and capacity on the proposed method are discussed in detail. The effectiveness of the proposed method for large AC interconnected power system segmentation is verified by simulations in two AC interconnected power systems.

In this paper, a novel flywheel energy storage device, called the flexible power conditioner, which integrates both the characteristics of the flywheel energy storage and the doubly-fed induction machine, is proposed to improve power system stability. A prototype is developed and its principle, composition, and design are described in detail. The control system is investigated and the operating characteristics are analyzed. The test results based on the prototype are presented and evaluated. The test results illustrate that the prototype meets the design requirement on power regulation and starting, and provides a cost-effective and effective means to improve power system stability.

A robust adaptive controller for a nonholonomic mobile robot with unknown kinematic and dynamic parameters is proposed. A kinematic controller whose output is the input of the relevant dynamic controller is provided by using the concept of backstepping. An adaptive algorithm is developed in the kinematic controller to approximate the unknown kinematic parameters, and a simple single-layer neural network is used to express the highly nonlinear robot dynamics in terms of the known and unknown parameters. In order to attenuate the effects of the uncertainties and disturbances on tracking performance, a sliding mode control term is added to the dynamic controller. In the deterministic design of feedback controllers for the uncertain dynamic systems, upper bounds on the norm of the uncertainties are an important clue to guarantee the stability of the closed-loop system. However, sometimes these upper bounds may not be easily obtained because of the complexity of the structure of the uncertainties. Thereby, simple adaptation laws are proposed to approximate upper bounds on the norm of the uncertainties to address this problem. The stability of the proposed control system is shown through the Lyapunov method. Lastly, a design example for a mobile robot with two actuated wheels is provided and the feasibility of the controller is demonstrated by numerical simulations.

To realize the fast and accurate detection of the edges from the blurry images, the fast multilevel fuzzy edge detection (FMFED) algorithm is proposed. The FMFED algorithm first enhances the image contrast by means of the fast multilevel fuzzy enhancement (FMFE) algorithm using the simple transformation function based on two image thresholds. Second, the edges are extracted from the enhanced image by the two-stage edge detection operator that identifies the edge candidates based on the local characteristics of the image and then determines the true edge pixels using the edge detection operator based on the extremum of the gradient values. Experimental results demonstrate that the FMFED algorithm can extract the thin edges and remove the false edges from the image, which leads to its better performance than the Sobel operator, Canny operator, traditional fuzzy edge detection algorithm, and other multilevel fuzzy edge detection algorithms

Focused ultrasound (FUS) combined with microbubbles is an attractive method to deliver therapeutic agents to brain tissue noninvasively, transiently and locally such as antibodies, gene vectors, liposomal drugs. The objective of this study is to investigate passive delivery outcome of liposomes after ultrasound mediated blood-brain barrier (BBB) disruption. Microbubbles were injected intraveneously through mice tail vein at 0.1 µL/g. Focused ultrasound (center frequency: 1.2819 MHz) was applied to mice brains with 10 ms pulse length and 1 Hz repetition frequency at acoustic power 1.1 W for 60 s. After sonication, 55-nm and 120-nm rhodamine-labeled liposomes were administered to mice intraveneously. Fluorescence imaging of brain coronal sections showed that the spatial distribution of delivered liposomes across BBB was characterized by scattered spots and heterogeneous. However, the quantitative analysis results indicated that passive deliveries of liposomes across BBB were confined, especially for 120-nm liposomes.

A 30-year-old woman presented with a painless left upper neck swelling for more than a week. Fibrolaryngoscope examination suggested nasopharyngeal carcinoma. FDG PET/CT was performed for an initial staging, which revealed intense activity in the soft tissue mass in the nasopharynx and cervical lymph nodes. However, biopsy from the nasopharyngeal lesion demonstrated tuberculosis.

The progressive current degradation and breakdown behaviors of GaN-based light emitting diodes under high reverse-bias stress are studied by combining the electrical, optical, and surface morphology characterizations. The current features a typical "soft breakdown" behavior, which is linearly correlated to an increase of the accumulative number of electroluminescence spots. The time-to-failure for each failure site approximately obeys a Weibull distribution with slopes of about 0.67 and 4.09 at the infant and wear-out periods, respectively. After breakdown, visible craters can be observed at the device surface as a result of transient electrostatic discharge. By performing focused ion beam cuts coupled with scan electron microscope, we observed a local current shunt path in the surface layer, caused by the rapid microstructure deterioration due to significant current heating effect, consistent well with the optical beam induced resistance change observations.

Three-dimensional (3D) temperature mapping method with high spatial resolution and acquisition rate is of vital importance in evaluating thermal processes in micro-environment. We have synthesized a new temperature-sensitive functional material (Rhodamine B functionalized Polydimethylsiloxane). By performing optical sectioning of this material, we established an advanced method for visualizing the micro-scale 3D thermal distribution inside microfluidic chip with down to 10 ms temporal resolution and 2 ~ 6°C temperature resolution depending the capture parameters. This method is successfully applied to monitor the local temperature variation throughout micro-droplet heat transfer process and further reveal exothermic nanoliter droplet reactions to be unique and milder than bench-top experiment.

Photocatalysis provides a ‘green’ approach to completely eliminate various kinds of contaminants that are fatal for current environmental and energy issues. Semiconductors are one of the most frequently used photocatalysts as they can absorb light over a wide spectral range. However, it is also well known that naked SiO2 is not an efficient photocatalyst due to its relatively large band gap, which could only absorb shortwave ultraviolet light. In this report, nanoscale particles of carbon-doped silicon dioxide (C-doped SiO2) for use in photocatalysis were successfully prepared by a facile one-pot thermal process using tetraethylorthosilicate (TEOS) as the source of both silicon and carbon. These particles were subsequently characterized by thermogravimetric analysis, X-ray diffraction, standard and high resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The C-doped SiO2 displayed outstanding photocatalytic properties, as evidenced by its catalysis of Rhodamine B degradation under near-UV irradiation. We propose that carbon doping of the SiO2 lattice creates new energy states between the bottom of the conduction band and the top of the valence band, which narrows the band gap of the material. As a result, the C-doped SiO2 nanoparticles exhibit excellent photocatalytic activities in a neutral environment. The novel synthesis reported herein for this material is both energy efficient and environmentally friendly and as such shows promise as a technique for low-cost, readily scalable industrial production.

Scarcity of the spectrum is becoming a major issue based on traditional frequency planning scheme, cognitive radio (CR) has been proposed for better spectrum utilization efficiency by intelligently sensing and opportunistic access. In this paper, a novel method is proposed to determine signal to noise ratio threshold (SNRT) based on transmission power and complexity of cognitive detector under lognormal shadowing conditions. Since there is tradeoff between detection probability and false alarm probability, we can maximize spectrum utilization efficiency with pre-determined detection performance,meanwhile SNRT is adjusted to void unacceptable interference to primary receiver (PR) and minimize complexity of cognitive detector according to transmission power. Numerical results will show that cognitive radio can adjust SNRT adaptively in order to guarantee the PR decoding signal from primary transmitter (PT) without unacceptable interference.

This paper proposes a double-fed induction machine with a flywheel energy storage system called the multifunctional Flexible Power Conditioner (FPC). It consists of the doubly-fed induction machine (DFIM) with very large rotating inertia and a voltage-source pulse width modulation (PWM) rectifier-inverter used as an AC exciter. A FPC 10kW model machine is developed. A simulation model for the model machine is built up and is simulated in some operating states, including phase modulation, subsynchronous, super-synchronous and so on. The model machine also is experiment in these proposed operating states. These results of simulation and experiment show that FPC is an effective way to compensate the unbalanced power and enhance the system stability. Satisfactory performance in decoupled control for the active and the reactive power and dynamic operation are obtained.