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To address the problem of decreased recognition accuracy of event samples in practical phase-sensitive optical time-domain reflectometer (Φ-OTDR) monitoring scenarios due to external environmental interference, this paper proposes a feature correction algorithm based on sample feature weighting method. By establishing a correlation evaluation method and a weight allocation scheme based on sample feature correlation, combined with the back propagation (BP) algorithm, an average recognition rate of 99.50% for four types of events (climbing, strong wind, knocking and background, 6000 samples) in strong wind environments was achieved, which is 3% higher than the algorithm using BP classifier. The results demonstrate that the proposed algorithm can effectively enhance the performance of Φ-OTDR in complex environments.

Based on first-principles calculation under density functional theory, the geometry, electronic and optical properties of the MoTe2/InSe heterojunction have been investigated. The results reveal that the MoTe2/InSe heterojunction has a typical type-Ⅱ band alignment and exhibits an indirect bandgap of 0.99 eV. In addition, the Z-scheme electron transport mechanism is capable of efficiently separating photogenerated carriers. The bandgap of the heterostructure changes regularly under applied electric field and exhibits a significant Giant Stark effect. Under an applied electric field of 0.5 V Å−1, the band alignment of the heterojunction shifts from type-Ⅱ to type-I. The application of strain produced comparable changes in the heterojunction. More importantly, the transition from semiconductor to metal is completed in the heterostructure under the applied electric field and strain. Furthermore, the MoTe2/InSe heterojunction retains the optical properties of two monolayers and produces greater light absorption on this basis, especially for UV light. The above results offer a theoretical basis for the application of MoTe2/InSe heterostructure in the next generation of photodetectors.

In order to understand the characteristics of breakdown process, plasma evolution and spectral emission in liquid jets laser-induced breakdown spectroscopy methods under the influence of the position variation between laser focus and gas–liquid interface, this work takes the plasma generated by laser-induced liquid jets as the object of study and discusses the changes in the spatial and temporal evolution characteristics and spectral radiation of the plasma when the position parameters between the laser focal point and the gas–liquid interface are different. The initial breakdown position is always between the front interface and the focus when the laser focus moves along the vertical direction of the interface, forming a phenomenon like ‘interface effect’. The relationship between laser pulse energy and breakdown probability exhibits a law similar to a ‘hysteresis curve’ in the study of breakdown threshold. In this work, plasma with smaller size, rounder shape, stronger radiation, higher temperature, and higher density can be produced when the focus position is in the liquid column 0.2 mm away from the front interface. Simultaneously, the spectral signal intensity and signal-to-back ratio of the characteristic peaks of target elements in water reach maximum values, and the spectral signal becomes more stable (relative standard deviation value reaches 2%). The Ca element’s ion radiation at 393.366 nm and atomic radiation at 422.673 nm are studied using narrow-band filtering imaging and time-space resolution spectroscopy. The findings demonstrate that the laws of ion and atomic radiation are not perfectly consistent in space and time.

The quantitative determination of heavy metals in aquatic products is of great importance for food security issues. Laser-induced breakdown spectroscopy (LIBS) has been used in a variety of foodstuff analysis, but is still limited by its low sensitivity when targeting trace heavy metals. In this work, we compare three sample enrichment methods, namely drying, carbonization, and ashing, for increasing detection sensitivity by LIBS analysis for Pb and Cr in oyster samples. The results demonstrate that carbonization can remove a significant amount of the contributions of organic elements C, H, N and O; meanwhile, the signals of the metallic elements such as Cu, Pb, Sr, Ca, Cr and Mg are enhanced by 3–6 times after carbonization, and further enhanced by 5–9 times after ashing. Such enhancement is not only due to the more concentrated metallic elements in the sample compared to the dried ones, but also the unifying of the matter in carbonized and ashed samples from which higher plasma temperature and electron density are observed. This condition favors the detection of trace elements. According to the calibration curves with univariate and multivariate analysis, the ashing method is considered to be the best choice. The limits of detection of the ashing method are 0.52 mg kg−1 for Pb and 0.08 mg kg−1 for Cr, which can detect the presence of heavy metals in the oysters exceeding the maximum limits of Pb and Cr required by the Chinese national standard. This method provides a promising application for the heavy metal contamination monitoring in the aquatic product industry.

Laser-induced breakdown spectroscopy (LIBS) is a capable technique for elementary analysis, while LIBS quantitation is still under development. In quantitation, precise laser focusing plays an important role because it ensures the distance between the laser and samples. In the present work, we employed spectral intensity as a direct way to assist laser focusing in LIBS quantitation for copper alloys. It is found that both the air emission and the copper line could be used to determine the position of the sample surface by referencing the intensity maximum. Nevertheless, the fine quantitation was only realized at the position where the air emission (e.g. O (I) 777.4 nm) reached intensity maximum, and also in this way, a repeatable quantitation was successfully achieved even after 120 days. The results suggested that the LIBS quantitation was highly dependent on the focusing position of the laser, and spectra-assisted focusing could be a simple way to find the identical condition for different samples’ detection. In the future, this method might be applicable in field measurements for LIBS analysis of solids.

With the networking completion of the Beidou navigation satellite system (BDS-3), the BDS-3 system was opened in the whole world on July 31, 2020. It is important practical significance to analyze the performance of the BDS-3 system and the GPS in terms of satellite common view timing comparison. In order to analyze the accuracy of timing comparison for BDS-3/GPS global navigation satellite system common view time, the comparison experimental of BDS-3/GPS with medium and long baseline is carried out based on satellite common view algorithm by using the National Metrology benchmark system of atomic time scale maintained by National Institute of Metrology (NIM), China. The timing model and algorithm of the BDS-3/GPS satellite common view algorithm are deduced in detail, and the stability of receiver clock difference and accuracy analysis of timing comparison for the BDS-3/GPS based on the satellite common view algorithm are compared and analyzed. The experimental results show that the stability of receiver clock difference of BDS-3 and GPS is respectively ns-level, but the stability of receiver clock difference of BDS-3 system is slightly better than that of GPS; the accuracy analysis of timing comparison for BDS-3 and GPS based on satellite common view algorithm is respectively better than 24 ns, but the accuracy analysis of timing comparison for BDS-3 system is slightly better than that of the GPS.

10 kV and 35 kV switchgear are the key equipment in the power grid, and the safety of their insulation is related to the stability of the entire power grid. But the accuracy of the traditional partial discharge detection method is difficult to meet the detection requirements of the new SF6 insulated switchgear. This work analyzes the feasibility of using the high-voltage sensor in the bushing to detect partial discharge, and the analysis shows that the synchronous signal and the partial discharge signal can be obtained from the bushing sensor. Detection experiments were carried out using three typical partial discharge models, with both HFCT and a bushing sensor. The measurement results show that the bushing sensor can effectively detect the partial discharge in the switchgear and obtain a PRPD plot similar to HFCT. It is also found that adjusting the sampling resistance can change the partial discharge detection range of the bushing sensor.

Aiming at the problem that a single positioning system cannot meet the indoor and outdoor high-precision positioning, GNSS/UWB integrated navigation system is proposed. Firstly, this paper introduces the development and research status of the global satellite navigation system; Secondly, The UWB positioning technology in indoor positioning technology is introduced; Finally, the development and research status of GNSS/UWB integrated navigation are introduced. The advantages and disadvantages of the single outdoor or indoor positioning system in the indoor and outdoor integrated navigation system are compared and analyzed. The results show that a single outdoor or indoor positioning system cannot meet the indoor and outdoor high-precision positioning, an effective method of GNSS/UWB fusion positioning is to improve the positioning accuracy and robustness, which can enhance the real-time in time, continuity in space and reliability in accuracy.

This work reported a novel dual-sensitive flexible sandwich sensor based on conductive natural biopolymers sponge electrode and polyvinylidene fluoride (PVDF) film with superiorities of high sensitivity, long lifespan and low density. The unique natural biopolymers sponge electrode, consisting of bidisperse magnetic particles and sodium alginate/chitosan (SA/CHI) with physically-crosslinked double-network structure, showed a high response capability to external magnetic fields. Besides, by combining the advantages of SA/CHI sponge electrode (high elasticity and flexibility) and PVDF film (exceptional stiffness and piezoelectricity), the SA/CHI/PVDF composite film also exhibited preferable mechanical strength and strain-dependent electrical property, which can simultaneously satisfy the requirements of high sensitivity detection to external magnetic fields and strains. Specifically, the relative resistance variation of SA/CHI/PVDF-1.00 sensor reached as high as 60.4% under a cycling loading of 240 mT magnetic field. Meanwhile, their electrical responses could also display a significant variation and relatively stable recoverability under periodic stretching, bending or compressing excitations. Afterwards, a potential working mechanism and equivalent circuit model were provided to study the magnetic/mechanic sensitivity of SA/CHI/PVDF sensors. Furthermore, a 4 × 4 SA/CHI/PVDF sensor array was developed to perceive and distinguish both magnetic field and compressive force, which indicated its favorable potential in wearable electronics and soft robotics.

Optically pumped whispering gallery mode (WGM) lasing has been observed in many freestanding microdisk structures. Dry etching is normally used to fabricate the microdisks, which causes severe sidewall damage, resulting in degradation of lasing performance, especially for ultra-small electrically-injected devices. In this paper, we demonstrate high quality microdisk cavities with 3.5 µm diameter, by combining a selective overgrowth approach and an epitaxial lattice-matched distributed Bragg reflector (DBR), topped with a highly reflective (>99%) dielectric DBR. InGaN polaritons are found to occur in the high-quality microcavities. WGM modes are measured, with the positions in good agreement with finite difference time domain simulations. Furthermore, lasing behaviour is observed with a threshold at 410 µW and a dominant mode at 488 nm.

Large aperture planar optical elements are required in high power laser systems, and the mid-spatial frequency error of the surface of the high-power laser component will affect the normal operation of the high-power laser system. In recent years, there are many new MRF devices, but these devices only improve the removal efficiency of polishing materials and ignore the stability of MRF tools. As we all know, the fluctuation of the MRF polishing ribbon will affect the stability of the removal function, which will make the surface of the processed component produce the mid-spatial frequency error. Therefore, based on the array magnetorheological pole structure newly developed in our laboratory, this paper tests its magnetic field distribution and studies the influencing factors of array magnetorheological ribbon fluctuation. Based on the magnetic field force, the effects of magnetorheological fluid flow, polishing wheel speed, and magnetic pole structure on ribbon fluctuation are analyzed. Finally, by using the improved array magnetorheological device to obtain a stable removal function, the volume removal efficiency of fused silica reaches 0.022mm3/min, which verifies the feasibility of the improved device and doubles the removal efficiency of magnetorheological finishing of a single ribbon. Therefore, we use controlled magnetorheological processing flow and speed to control ribbon fluctuations and designing the magnetic pole structure, to control the stability of magnetorheological processing.

We propose a density-near-zero piezoelectric metamaterial for realizing tunable sound transmission in real-time. The proposed mechanism is that the static voltage exerted on piezoelectric patches breaks the tension balance of the middle membrane, making the resonance frequency of the hybrid membrane structure dependence of static voltage. The numerical results verify the theoretical predictions and the effectiveness of the resulting device is demonstrated via multi-extraordinary phenomena at two predesigned frequencies. We anticipate our methodology to offer new possibilities for metamaterial-based piezoelectric devices and may promote applications in various fields such as acoustic communication.

Acoustic metasurfaces can manipulate acoustic waves at subwavelength scales, thus proved to have advantages in constructing novel compact analog computing (CAC) systems. Here, we design an acoustic CAC system based on a nondispersive focusing metasurface (FM) and a reconfigurable reflective metasurface (RRM), which can perform broadband and tunable mathematical operations. The nondispersive FM consists of the sandwich-like-structured units, featuring the non-dispersive effective refractive indexes and high transmission efficiency. The RRM is formed by the amplitude modulator (AM) and π/2-phase modulator (π/2-PM), where the moving regions in the AM and π/2-PM can control the reflection amplitude and phase distribution of RRM, respectively. The numerical results show that the proposed CAC system can perform spatial differentiation and integration on the incident acoustic wave in the frequency range from 3.0 kHz to 3.9 kHz. This work promises the broadband and tunability that are critical for practical computing devices, paving the way towards acoustic computing applications, wave processing and manipulations.

Nowadays, more importance has been attached to the energy consumption of household energy storage inverters. This paper proposes a design scheme of original-auxiliary dual power supply for household energy storage inverters, so that the inverter uses a large-capacity power supply when it is loaded with medium or large loads, and uses a small-capacity power supply when it is loaded with light loads or no load, and avoids large losses caused by the two-stage inverter when using a large-capacity power supply with a small load with the purpose of energy saving. The solution adopts a peak detection circuit on the AC power supply side, which can accurately detect the tiny current when the 1∼3W-load is connected, so as to accurately judge the access and exit of the load, so that the power supply can enter or exit the power saving mode of the small-capacity power supply in a timely and flexible manner. In this paper, the feasibility and rationality of the scheme are tested by simulation, and it is proved that the power saving effect of the scheme is remarkable.

The Loschmidt echo is a useful diagnostic for the perfection of quantum time-reversal process and the sensitivity of quantum evolution to small perturbations. The main challenge for measuring the Loschmidt echo is the time reversal of a quantum evolution. In this work, we demonstrate the measurement of the Loschmidt echo in a superconducting 10-qubit system using Floquet engineering and discuss the imperfection of an initial Bell-state recovery arising from the next-nearest-neighbor (NNN) coupling present in the qubit device. Our results show that the Loschmidt echo is very sensitive to small perturbations during quantum-state evolution, in contrast to the quantities like qubit population that is often considered in the time-reversal experiment. These properties may be employed for the investigation of multiqubit system concerning many-body decoherence and entanglement, etc., especially when devices with reduced or vanishing NNN coupling are used.

Optical physically unclonable functions (PUFs) have great potential in the security identification of the internet of things. In this work, electrospun nanofibers are proposed as a candidate for a nanoscale, robust, stable and scalable PUF. The dark-field reflectance images of the polymer fibers are quantitatively analyzed by the Hough transform. We find that the fiber length and orientation distribution reach an optimal point as the fiber density (number of fibers detected by Hough ttansform) grows up over 850 in 400 × 400 pixels for a polyvinylpyrrolidone (PVP) nanofiber-based PUF device. Subsequently, we test the robustness and randomness of the PUF pattern by using the fiber amount as an encoding feature, generating a reconstruction success rate of over 80% and simultaneously an entropy of 260 bits within a mean size of 4 cm2. A scale-invariant algorithm is adopted to identify the uniqueness of each pattern on a 256-sensor device. Furthermore, the thermo-, moisture and photostability of the authentication process are systematically investigated by comparing the polyacrylonitrile to the PVP system.

This study aims to improve the real-time accuracy of cooling load forecasting for heating, ventilating and air-conditioning systems (HVAC). This article takes the cooling load in a study room in Qingdao, China, which has been put into use for the first time, as the research object, and establishes a TRNSYS simulation platform to obtain sufficient load data. After using the mean influence value (MIV) and Spearman correlation coefficient to screen the characteristic variables, a hybrid algorithm (CS-CPSO) based on cuckoo search (CS) and particle swarm optimization (PSO) is proposed. Firstly, the iterative extremum is introduced to PSO, secondly, mechanism of levy random flight to generate random new nest in CS is used to initialize PSO particles adaptively, Finally, the optimization algorithm is applied to optimize the back propagation (BP) and support vector regression (SVR) load training models (WBP, WSVR, RBP, RSVR) of the working day (W) and rest day (R), respectively. The maximum grey correlation coefficient is utilized to establish the both models (CS-CPSO-CW, CS-CPSO-CR) of the working day (W) and rest day (R) based on CS-CPSO. In this way, the forecasting results are optimized and then compared with the regression prediction method. The analysis shows that the accuracy of the optimized BP model and SVR model are improved and fully considering the differences, the accuracy of the cooling load prediction is effectively promoted by separately, optimal selection between the prediction values of advanced models (CS-CPSO-WBP, CS-CPSO-WSVR and CS-CPSO-RBP, CS-CPSO-RSVR) gives full play to each algorithm’s advantages and makes up for their shortcomings, and it greatly increases reliability and improves accuracy, which in turn provides the basis for the optimal plan, control, and operation of the HVAC.

Emissions by magnetic polarons and spin-coupled d–d transitions in diluted magnetic semiconductors (DMSs) have become a popular research field due to their unusual optical behaviors. In this work, high-quality NiI2(II)-doped CdS nanobelts are synthesized via chemical vapor deposition (CVD), and then characterized by scanning electron microscopy (SEM), x-ray diffraction, x-ray photoelectron spectroscopy (XPS), and Raman scattering. At low temperatures, the photoluminescence (PL) spectra of the Ni-doped nanobelts demonstrate three peaks near the band edge: the free exciton (FX) peak, the exciton magnetic polaron (EMP) peak out of ferromagnetically coupled spins coupled with FXs, and a small higher-energy peak from the interaction of antiferromagnetic coupled Ni pairs and FXs, called antiferromagnetic magnetic polarons (AMPs). With a higher Ni doping concentration, in addition to the d–d transitions of single Ni ions at 620 nm and 760 nm, two other PL peaks appear at 530 nm and 685 nm, attributed to another EMP emission and the d–d transitions of the antiferromagnetic coupled Ni2+–Ni2+ pair, respectively. Furthermore, single-mode lasing at the first EMP is excited by a femtosecond laser pulse, proving a coherent bosonic lasing of the EMP condensate out of complicated states. These results show that the coupled spins play an important role in forming magnetic polaron and implementing related optical responses.

Superconducting transmon qubits are the leading platform in solid-state quantum computing and quantum simulation applications. In this work, we develop a fabrication process for the transmon multiqubit device with niobium base layers, shadow evaporated Josephson junctions, and airbridges across the qubit control lines to suppress crosstalk. Our results show that the multiqubit devices have well-characterized readout resonators, and the energy relaxation and Ramsey (spin-echo) dephasing times up to ~40 μs and 14 (47) μs, respectively. We perform single-qubit gate operations which demonstrate a maximum gate fidelity of 99.97%. In addition, two-qubit vacuum Rabi oscillations are measured to evaluate the coupling strength between qubits, and the crosstalk among qubits is found to be less than 1% with the fabricated airbridges. Further improvements of the qubit coherence performance using the present fabrication process will be discussed.

With the promotion of unattended substations across the country, intrusion detection technology for people in important areas of substations has become an important research area. This article focuses on the problem of personnel entering important areas of substations for the purpose of man-made destruction, and proposes an improved two-frame difference method A moving target detection method combined with the background subtraction method. This method is based on the two-frame difference method, taking into account the impact of changes in illumination, and avoids the image sequence by combining the difference map of the background subtraction method and the two-frame difference method. The “double shadow” phenomenon caused by the difference method can also avoid the situation that the background subtraction method misjudges the sudden change of light as a moving target, improves the recognition accuracy, and can meet the real-time requirements of the substation intelligent monitoring system.

Focus on the problem that the Multiple Kernel Boosting(MKBoost) algorithm is sensitive to noise, a Multiple Kernel Boosting algorithm based on weight update and kernel selection is proposed. Firstly, the algorithm use the combined classification error rate of the previously selected classifier and the current classifier to be selected as the selection index of the kernel function in the weak classifier before the kernel of the base classifier is selected in each iteration; Secondly, in the weight update stage, a new weight update method is constructed by fusing the noise-detection and the average of weights in Multiple Kernel Boosting algorithm, which reduce the sensitivity to noise samples. Among the 8 of UCI data sets with varying levels of noise, the algorithm was compared with MKBoost-D1, MKBoost-D2, under the accuracy criteria, it performed better than traditional MKBoost algorithms. Experimental results show that the algorithm is able to effectively reduce the sensitivity of MKBoost to noise, and also has better robustness than traditional MKBoost algorithms.

The magnetic excitons in diluted magnetic semiconductor (DMS) have varied formats due to the inhomogeneous phases out of doping concentration and/or structural relaxations or defects. Here the high quality cobalt-doped zinc blende ZnSe nanoribbons (NRs) were synthesized, showing bright and color-variable emissions from blue, yellow to a little mixed white colors. Their power and temperature dependent micro-photoluminescence (PL) spectra have been obtained in which two emission bands, one magnetic exciton band near the band-edge and a Co2+ high-level d–d transition emission band at 550 nm out of their ferromagnetic (FM) coupled aggregates in ZnSe lattice, both bands could also be reflected by a nonlinear optical absorption enhancement. The easy formed stacking fault defects in a chemical vapor deposition (CVD) grown ZnSe zincblende NR took part in the above optical processes out of magnetic polaronic excitons (PXs). The femtosecond (fs) laser pulse pumping on single ZnSe:Co NR produces obvious lasing behavior but with profile of a complicated magnetic exciton interactions with indication of a crossover from collective exciton magnetic polarons (EMP) to bound magnetic polaron (BMP) scattering in Co doped ZnSe NR. These findings indicate the complication of the magnetic coupling natures in varied DMS structures, whose optical properties have been found to be highly nonlinear, due to the involvement of the spin–spin, spin–exciton and spin–phonon interactions, verified by the theoretic calculation in Yang X-T et al (2019 Interstitial Zn-modulated ferromagnetism in Co-doped ZnSe Mater. Res. Express 6 106121).

This paper reports on design, measurement and optimisation of a Tamm plasmon metal-DBR cavity for use in the green part of the visible spectrum. It uses an optimised silver layer thickness and a porous DBR created using a novel electro-chemical etching technique. This device has applications in low cost lasers, photodetectors and photoconductive switches for the visible wavelength range., 4 pages, 3 figures

Now, the computer multimedia has been widely applied in nursing field, provides the reform and development of the nursing teaching, nursing teachers must have the information quality, can use computer aided to creative teaching activities, this topic research has very important meaning, can for future nursing education means and methods to provide a very important idea and mode, at the same time, computer aided technology can promote the reform of nursing education system, the use of modern education technology means, improve the education level, conducive to the cultivation of nursing students to become the new information-based nursing talents, at the same time, Nursing teachers should adapt to computer multimedia teaching, strengthen information technology training, and become a nursing teacher with good information awareness, information ability and information quality[1].

With the rapid economic development, subway-based rail transit is spreading all over the country, and efficient prediction of rail passenger flow is the key to alleviating traffic pressure. In view of the time-series characteristics of subway passenger flow data, the author uses the simulation results to show that the ARIMA model has higher accuracy and better effect in predicting the rail transit flow.

The specific polarization of radially polarized lasers with cylindrical structures and longitudinal electric fields at their focal spots are of interest, as are the fundamental characteristics of electromagnetic (EM) solitons. Compared with linearly and circularly polarized lasers, radially polarized lasers have a more perfect symmetry, which makes them more suitable for studying the topological structure in laser–plasma interaction. We report the structural features of EM solitons induced via a radially polarized laser on the basis of three-dimensional particle-in-cell simulations. It has been discovered that a fractal-like structure is produced due to the interaction between the radially polarized laser and the plasma, and that this structure indirectly originates from the Weibel instability of the electron ring. This novel regime will allow potential applications such as the manipulation of relativistic electrons, mode filtering, and fractal-like particle acceleration.

Molecular dynamics simulations are performed to gain insights into the structural and vibrational properties of interface between porous and fused silica. The Si–O bonds formed in the interface exhibit the same lengths as the bulk material, whereas the coordination defects in the interface are at an intermediate level as compared with the dense and porous structures. Clustered bonds are identified from the interface, which are associated with the reorganization of the silica surface. The bond angle distributions show that the O–Si–O bond angles keep the average value of 109°, whereas the Si–O–Si angles of the interface present in a similar manner to those in porous silica. Despite the slight structural differences, similarities in the vibrations are observed, which could further demonstrate the stability of porous silica films coated on the fused silica.

With the urgent need for applied talents in foreign-related languages in China, the importance of English is also increasing. The construction and development of English teachers in colleges and universities is related to their English teaching level. Therefore, colleges and universities should actively solve the problem of the construction and development of teachers’ team based on big data analysis. The construction of teachers’ specialization is the foundation for the survival of higher education. The work of colleges and universities should closely focus on the construction of teachers’ specialization and actively explore and think about the effective connotative development model based on big data analysis. Therefore, on the basis of deeply exploring and exploring the characteristics of teachers’ team construction in private colleges and universities, exploring the connotative development mode of teachers’ team construction is conducive to the survival of colleges and universities, the overall improvement of teachers’ quality and the level and quality of personnel training.

A thermoresponsive hydrogel that was composed of 2-hydroxy-3-isopropoxypropyl starch (HIPS) and alginate was synthesized via cross-linking with hybrid crosslinkers including ethylene glycol diglycidyl ether (EDGE) and calcium chloride (CaCl2). Attenuated total reflection infrared spectroscopy (ATR-IR), thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG) were used to confirm that cross-linking occurred. The porous architecture of the HIPS/SA composite hydrogels was investigated using scanning electron microscopy (SEM). Composite hydrogels had a tunable volume phase transition temperature (VPTT) that was in the range from 29.4 to 40.2 °C and resulted from changes in the compositions (HIPS concentration from 5.5 to 7.5 wt%). It was also found that the presence of NaCl (0 to 20 g l−1) or organic solvents (alcohols, 0 to 50 g l−1) in aqueous medium changed the VPTT of the composite hydrogels; also, the VPTT decreased as the concentration of NaCl or organic solvents increased. Additionally, alcohols that have long carbon chains (isopropanol > ethanol > methanol) exhibited a more significant effect on the VPTT of hydrogel. The hydrogel could shed and absorb most of the water in a very short time and demonstrate a stable reversible swelling-deswelling property after 5 swelling-deswelling cycles.

In view of the problems in the practical application of traditional urban Lighting systems, such as inconvenient centralized control of street lamps, untimely information monitoring, and low efficiency of human inspection methods, a design scheme for street lamp monitoring systems based on narrow-band Internet of Things (NB-IoT) technology is proposed. In this solution, the STM32L431 RCT6 chip is used as the main control chip, and the NB-IoT module is used as the communication module. It is connected to the Huawei Internet of Things management platform, and an application program is developed on the application side to remotely monitor the street lights in real time. The experimental results show that the system realizes real-time monitoring and intelligent control of street lamps.

Laser-induced breakdown spectroscopy (LIBS) has been proven to be an attractive technique for the in-situ oceanic applications. However, when applying LIBS into deep-sea, the pressure effect caused by different ocean depth is inescapable and could have great influence on the LIBS signals. In this work, spectral characteristics of underwater LIBS were investigated as a function of pressure in the range from 0.1 to 45 MPa. A high-pressure chamber built in the laboratory was used to simulate the high-pressure environment of deep-sea. Optimal laser energy and detection delay were first determined under different pressure conditions and were shown to be independent on the external pressure. The increase in pressure has a significant impact both on the peak intensity and line broadening of the observed spectra. The peak intensity of Na, Li and K lines increases with the increasing pressure until a maximum intensity reached at 12.5 MPa. Above this value, the peak intensity decreases gradually up to 45 MPa. For Ca line, the maximum intensity was observed at 30 MPa. The line broadening keeps constant at low pressures from 0.1 to 10 MPa while it increases linearly at higher pressures, indicating a higher electron density caused by the compression effect of the high external pressure. We also compared the spectral data obtained from the high-pressure chamber and from the field sea trials, and the good consistency between the laboratory data and sea-trial data suggested the key role of pressure effect on underwater LIBS signals for the practical deep-sea applications.

The methods to study the dynamic characteristics of diesel engine structure include finite element analysis method and experimental analysis method. It is difficult to establish an accurate finite element model, since the results of finite element analysis methods are often not accurate. For the experimental analysis method, it is mainly divided into the traditional Experimental Modal Analysis (EMA) and the Operational Modal Analysis (OMA). The EMA method always needs to measure the excitation force of the diesel engine and the vibration response of the structure simultaneously. And the influence of motion factors on the structure dynamics cannot be considered. The structure is excitated by the working environment, and only analyzes the modal parameters of the structure with the vibration response. Few scholars analyze the OMA for diesel engines. This paper proposes a new method to identify the modal parameters of diesel engine based on self-excitation. In this paper, the theory of self-excitation mode parameter identification is demonstrated by derivation, and the validity of the method is verified.

At present, the methods to study the dynamic characteristics of diesel engine structure include finite element analysis method and experimental analysis method. Among, 60% of the structural stiffness and 90% of the damping ratio of the whole diesel engine come from the joint part, and the dynamic characteristics of the joint part of the diesel engine are very complex, so it is difficult to establish an accurate finite element model, and the results of finite element analysis methods are often not accurate. For the experimental analysis method, it is mainly divided into the traditional Experimental Modal Analysis method (EMA) and the Operational Modal Analysis (OMA). The EMA it alays needs to measure the excitation force of the diesel engine and the vibration response of the structure, simultaneously. And the influence of motion factors on the structure dynamics cannot be considered. The structure is excitated by the working environment, and only analyzes the modal parameters of the structure with the vibration response. Few scholars analyze the OMA for diesel engines. This paper proposes a new method to identify the modal parameters of diesel engine based on dry run. In this paper, the design and research of the motion law of the air-running self-excitation is carried out, and the validity of the method is verified.

After the September 18th Incident, anti-Japanese War and national salvation songs became the theme in song creation, where the Anti-Japanese Amalgamated Army songs were among the most outstanding. In this paper, the style of Anti-Japanese Amalgamated Army songs in Mudanjiang River Basin during the Anti-Japanese War was analyzed and summarized.

O-doped Bi2S3 is a promising candidate for interfacial resistive switching. Here we introduce the oxygen into chemical-bath-deposited Bi2S3 thin film simply by annealing in air, and study the electrode effects to its resistive switching by comparing the switching behaviors of O-doped Bi2S3 grown on different conductive substrate. It shows that the oxygen-doping in Bi2S3 via air annealing is an effective method to introduce traps to the interface between O-doped Bi2S3 and the conductive substrate of F-doped SnO2 or Pt, and produces the bipolar resistive switching. Moreover, by analyzing the I-V characteristics and differential-conductance features of both O-Bi2S3/FTO, and O-Bi2S3/Pt system, we founds that using Pt as the substrate could produce more robust resistive switching, and attribute it to the stronger Fermi-level pinning of Pt with heavier work function than that of FTO.

We report a fabrication process and characterization of the Josephson parametric amplifier (JPA) for the single-shot quantum state measurement of superconducting multiqubit system. The device is prepared using Nb film as its base layer, which is convenient in the sample patterning process like e-beam lithography and film etching. Our results show that the JPA has a bandwidth up to 600 MHz with gain above 15 dB and noise temperature approaching the quantum limit. The qubit state differentiation measurements demonstrate the signal-to-noise ratio around 3 and the readout fidelity above 97% and 91% for the ground and first-excited states, respectively.

Molecular dynamics simulations are performed to investigate the effects of low-energy recoils on the microscopic structure of porous silica. Exhibiting a logistic growth with the recoil energy, the displacement probability of Si is shown to be smaller than that of O at the same primary knock-on level. Computations of pair distribution functions and bond angle distributions reveal that this material upon irradiation with energies around the displacement thresholds mainly undergoes structural changes in the medium-range order. In the porous network, while the formation of nonbridging oxygen defects tends to induce shorter Si–O bonds than those formed by bridging oxygen atoms, a remarkable increase of inter-tetrahedral bond angles created by multiple recoils can be observed and associated with the rearrangement of ring statistics.