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With the development of science and technology and the progress of wireless sensor network technology, a variety of intelligent electronic products are used more and more widely in people's lives. High technology and intelligent technology have entered residential home users from intelligent buildings, and home intelligent technology has become a cutting-edge technology topic. The development of mobile Internet provides a new platform for home decoration, which is of great significance in promoting the formation of smart families and smart communities. Curtain is an important element in interior decoration design. It is of great practical value to develop a mobile virtual display system that can manage curtains and provide curtain decoration effects. The design idea of modularization is adopted, and the design process of wireless communication module, relay module, key module, power protection and level conversion module of the system is emphatically analyzed. The basic working principle and operation method of the system are introduced, and the server and client software based on TCP communication protocol are designed to realize the remote control of curtains through the Internet or personal mobile devices. The actual results show that the scheme can be applied to the home or office environment, and has the characteristics of high stability and simple operation.

As the world’s need for renewable energy has grown in recent years, the possibility of creating and collecting deep-sea wind energy has become a research hotspot. Floating wind turbines need damping devices to provide a stable working state and structural safety. Damping systems are often used for offshore floating constructions based on various operating principles and locations. Damping technology of various sorts is continually being researched for various demands, such as floating body size, form, and operating circumstances. To react to complex and changeable external circumstances, new perspectives on damping method categorization and selection are required. The conclusion was reached by classifying and comparing, tuned liquid column dampers are often employed in operational conditions. Dampers with power sources perform well in extreme conditions, such as Magnetorheological dampers. Rotational inertia dampers can greatly decrease torque but have yet to be widely employed in floating wind turbines. The purpose of this study is to review the latest improvements in offshore damping technology. The research results will provide characteristics and design references for future vibration damping of floating offshore wind turbines.

For a long time, some companies have basically no revenue, but have not delisted from the market with poor performance, reflecting the embarrassment of the system. One of the reasons for the difficulty of enterprise delisting is the existence of ST companies in the market, which results in the scarcity of shell resources of listed companies. How to optimize the market exit mechanism has become an urgent problem to be solved. This paper selects Chinese listed companies that were processed by ST from 1998 to 2020 as the research object, and uses survival analysis to study the survival problems of ST companies, that is, the time rule of ST companies' delisting and delisting. The results show that the probability of capping incidents of listed companies after the implementation of special treatment increases first and then decreases, reaching a peak in the second year after the implementation of ST, and a substantial decline in the third year, and it can be achieved in the sixth year and beyond. Few ST companies have decapitated; the probability of delisting events of listed companies after the implementation of special treatment also increases first and then decreases, reaching a peak in the third year after the implementation of ST. In the fifth year and beyond, few ST companies have retired. city.

Objectives To review the literature systematically to compare the performance of adhesive precoated flash-free bonding systems with conventional adhesive precoated (APC) and operator-coated (OPC) bonding systems. Materials and Methods PubMed, Cochrane Library, Web of Science, and Embase were searched for potential eligible studies. Study selection and data collection were conducted independently. Statistical analysis was performed by Review Manager 5.3. The Cochran Q test was used to test heterogeneity in the included studies. Risk of bias was evaluated using Cochrane RoB 2.0 tool for randomized controlled trials. Results Six studies were included and the overall risk-of-bias judgment was low risk of bias to some concerns. The results of the meta-analyses showed that flash-free required significantly less bonding time than APC (mean difference [MD]: −1.56; 95% confidence intervals [CIs]: −2.56 to −0.56), and no significant differences were found in bond failure rates (risk ratio [RR]: 1.54; 95% Cis: 0.27 to 8.89) and adhesive remnant index (ARI) (MD: −0.50; 95% CIs: −1.14 to 0.14) between them. Qualitative analysis showed that flash-free might have a positive effect on enamel demineralization compared to APC but the quantity of plaque did not differ between them. Conclusions The flash-free bonding system significantly reduced bonding time and it had comparable bond failure rates with APC. So far, there is not enough evidence to support its positive effect on reducing enamel demineralization and the pathogenic bacteria around brackets. In summary, flash-free might be a better choice for clinical bracket bonding.

Objective: This study investigated the association of the TaqI (rs731236 T>C) polymorphism in the VDR gene with dental caries. Methods: A comprehensive literature search was performed in PubMed, Web of Science, Embase, SinoMed (the Chinese biomedical literature service system), and the Wiley Online Library. Overall comparisons and subgroup analyses based on ethnicity and the presence of dental caries in dentition were performed. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess associations between gene polymorphisms and the risk of dental caries. Results: Seven articles were included in this meta-analysis. The pooled results revealed a significant association of the TaqI (rs731236 T>C) polymorphism with dental caries in the allele contrast model (C vs. T: OR = 1.24, 95% CI = 1.07–1.44, I2 = 42%, p = 0.005) and in the recessive genetic model (CC vs. TT/CT: OR = 1.38, 95% CI = 1.03–1.84, I2 = 0%, p = 0.03). A stratified analysis based on ethnicity revealed a significant association between the TaqI (rs731236 T>C) polymorphism and the risk of dental caries in Asians (C vs. T: OR = 1.28, 95% CI = 1.06–1.54, I2 = 60%, p = 0.009). Subgroup analysis based on the presence of dental caries in dentition found a significant association of the TaqI (rs731236 T>C) polymorphism with permanent tooth caries in the allele contrast model (C vs. T: OR = 1.40, 95% CI = 1.11–1.77, I2 = 76%, p = 0.005) and the recessive genetic model (CC vs. TT/CT: OR = 1.44, 95% CI = 1.03–2.00, I2 = 0%, p = 0.03). Conclusion: The results of this meta-analysis suggest that the C allele and CC genotype of the TaqI (rs731236 T>C) polymorphism in the VDR gene are associated with an increased risk of dental caries.

In this paper, eight different SRAM cells are studied and evaluated with a 65nm CMOS technology. The cells were designed with radiation-hardening-by-design approaches including schematic and layout techniques. The eight types of cells were placed into eight pages of an SRAM test chip. The alpha and proton irradiation demonstrated that the Dual Interlocked Cell (DICE) has the best radiation-tolerant performance, but requires the largest area. The 6T and 11T cells designed with charge cancellation techniques can reduce soft errors up to 2-3 times with less area overhead. Several DICE variants were developed with reduced area overhead and showed SEU resilience performance equivalent to DICE. Simulation results are also presented in this paper to validate the findings.

A triple modular redundancy SRAM was designed as the embedded high-speed memory for a radiation-tolerant ARM processor with ST Microelectronics 28-nm FDSOI technology. The single event upset (SEU) cross-section of the SRAM was tested by using heavy ions with the linear energy transfer of 15.0 meV.cm2.mg−1 in both non-TMR and TMR modes with different accumulated fluence. The SRAM cell was also simulated by using Cogenda TCAD simulation suite and the cross section was calculated by using analytic method. The results showed the cross-section is around 2E-10 cm2/bit in non-TMR mode, and in TMR mode it varied from one to several orders lower than the non-TMR mode according to the specific accumulated fluence. As a scrubbing circuit was designed to reduce the accumulated number of SEUs in the SRAM, the Failure In Time (FIT) rate at sea level in New York City could be as low as 8E-11, which is robust enough for the whole circuit.

Human periodontal ligament cells (hPDLCs) are important source of periodontal tissue reconstruction. Under chronic inflammation, the multi-directional differentiation potential and chemotaxis in hPDLCs are decreased. Therefore, inhibiting inflammatory microenvironment and improving the functional characteristics of stem cells can better promote periodontal tissue reconstruction. This study was to investigate the effect of astaxanthin (AST) on lipopolysaccharide (LPS)-induced inflammation in hPDLCs and the underlying mechanisms.hPDLCs were isolated and cultured in vitro, and vimentin and keratin immunocytochemical staining were used to identify hPDLCs. CCK-8 assay was used to measure the effects of AST (1, 5, 10, 20, 50, 100, and 200 μmol/L) on proliferation of hPDLCs. Quantitative RT-PCR (RT-qPCR) and ELISA were used to measure the mRNA and protein expression of inflammatory factors (IL-6, IL-1β, and TNF-α) in the control (Con) group, the LPS group, and the LPS+AST (5, 10, 20, and 50 μmol/L) group. Western blotting was used to detect the protein expression of IKBα, phosphorylated IKBα (p-IKBα), and p65 in the Con group, the LPS group, the AST (20 μmol/L) group, and the LPS+AST (20 μmol/L) group. After 10 μmol/L PDTC treatment, the mRNA and protein expressions of IL-6, IL-1β, and TNF-α were detected by RT-qPCR and ELISA.Cell morphology and immunocytochemical staining showed that the cells were in line with the characteristics of hPDLCs. Treatment with AST could promote the proliferation of hPDLCs, which reached the peak at 20 μmol/L. The mRNA and protein expressions of IL-6, IL-1β, and TNF-α in the LPS group were higher than those in the Con group (allAST promotes the proliferation of hPDLCs, which is related to suppression of LPS-induced the secretion of inflammatory factors via inhibiting the activation of NF-κB signaling pathway.

Background Temporary anchorage devices have been used for decades in orthodontic practice for many applications. The aim of this systematic review was to assess the effectiveness of orthodontic temporary anchorage devices in canine retraction during the two-step technique. Methods A search was systematically performed for articles published prior to June 30, 2019 in five electronic databases (PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science, Scopus). The risk of bias was assessed using the Cochrane risk of bias tool for randomized controlled trials (RCTs) and the risk of bias in nonrandomized studies of interventions (ROBINS-I) tool for controlled clinical trials (CCTs). The Grading of Recommendation, Assessment, Development and Evaluation (GRADE) approach was used for the quality assessment. Data concerning the mean difference in mesial molar movement and extent of canine retraction were extracted for statistical analysis. The mean differences and 95% confidence intervals were analyzed for continuous data. A meta-analysis with a random-effects model for comparable outcomes was carried out. Results Three RCTs and five CCTs were finally included. Meta-analysis showed a significant increase not only in anchorage preservation in the implant anchorage group in both the maxilla (1.56 mm, 95% CI: 1.14 to 1.98, P P P = 0.001) and the mandible (0.26 mm, 95% CI: 0.02 to 0.49, P = 0.03). Conclusions There is very low-quality evidence showing that implant anchorage is more efficient than conventional anchorage during canine retraction. Additional high-quality studies are needed.

Research on single event effects (SEEs) is significant to the design and manufacture of modern electronic devices. By applying two photon absorption (TPA) ultra-fast pulsed lasers, extra electron-hole pairs (EHPs) are generated in a desired location on a chip, simulating the process that could occur in the circuit by energetic particles. In this study, a SEE sensitivity mapping system is described which uses this method to generate real-time sensitivity maps for various electronic devices. The system hardware includes an attenuator to control the energy, a Pockels cell as a fast-optical switcher and a mirror&ndash, mirror module to project the laser beam into a certain location. The system software developed for this application controls the laser system, automatically generates sensitivity maps, communicates with the testing devices and logs the SEE results. The two main features of this laser mapping system are: high scanning velocity for large area scanning (about 1 &times, 1 mm) and high spatial resolution for small area scanning (about 1 &times, 1 &mu, m). To verify this mapping system, sensitivity maps were generated for static random access memory (SRAM) built with 65 nm technology and for commercial operational amplifiers (op-amps). The achieved sensitivity maps were compared with circuitry analysis and laser testing results, confirming this mapping system to be effective.

Additional file 2. Articles Excluded After Full-Text Evaluation Based on Eligibility Criteria

Additional file 1. Searching strategy

Background: To assess the effectiveness of orthodontic temporary anchorage devices in canine retraction during two-step technique. Methods: The search was systematically performed up to June 2019 in five electronic databases (PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science, Scopus). A risk of bias assessment was performed using the Cochrane Risk of Bias Tool for Randomized Controlled Trials (RCTs) and the Risk of Bias in Nonrandomized Studies - of Interventions (ROBINS-I) tool for controlled clinical trials (CCTs) . The Grades of Recommendation, Assessment, Development and Evaluation (GRADE) approach was applied for quality assessment. Data concerning the mean difference in mesial molar movement and extent of canine retraction were extracted for statistical analysis. The mean difference and 95% confidence interval were analyzed for continuous data. A meta-analysis with a random-effects model for comparable outcomes was carried out. Results: Three RCTs and five CCTs were finally included. Meta-analysis showed a significant increase not only in anchorage preservation in the implant anchorage group in both the maxilla (1. 56 mm , 95% CI: 1.14 to 1.98, P

The high frequency (HF) isolation transformer is the core element of a dual-active-bridge (DAB) bi-directional high-power DC-DC converter. At high frequency high power conversion, providing compact and efficient transformer design solutions need to consider the magnetic, electric as well as thermal aspect thoroughly and carefully to ensure the reliability and efficiency of the whole system. Detailed design considerations for a HF isolation transformer in a DAB conversion system are presented in this paper taking into consideration the insulation, high frequency magnetics characteristics, skin-proximity effects at high switching frequency as well as the thermal-fluid interaction analysis. Special attention is paid to the leakage inductance since improper value leads to an undesirable overshoot on the device voltage which may cause the SiC failure. This paper also presents the a multi-objective optimization design methodology applied to a 25kVA/25kHz, 1500V/750V transformer intended for DC-DC stage in 1MVA SiC-based solid state transformer (SST) and the Pareto optimal sets under different cooling methods are derived and analyzed. Comparison between different magnetic materials and different operation conditions are also carried out to find the characteristics variation of the designed transformer. The merit of the optimal design are validated through finite element modeling (FEM) and computational fluid dynamics (CFD) simulations.

Single-event effects (SEEs) in integrated circuits and devices can be studied by utilizing ultra-fast pulsed laser system through Two Photon Absorption process. This paper presents technical ways to characterize key factors for laser based SEEs mapping testing system: output power from laser source, spot size focused by objective lens, opening window of Pockels cell, and calibration of injected laser energy. The laser based SEEs mapping testing system can work in a stable and controllable status by applying these methods. Furthermore, a sensitivity map of a Static Random Access Memory (SRAM) cell with a 65 nm technique node was created through the established laser system. The sensitivity map of the SRAM cell was compared to a map generated by a commercial simulation tool (TFIT), and the two matched well. In addition, experiments in this paper also provided energy distribution profile along Z axis that is the direction of the pulsed laser injection and threshold energy for different SRAM structures.

In order to effectively control vessel rudder under the random interference, this paper presented an innovative method based on extended linear-quadratic regulator (LQR) control method and adaptive genetic algorithm (AGA). With respect to the actual vessel navigation environment, the extended LQR control method is explored by using a series of calculus transformation under the random interference. Besides, the AGA is utilized to optimize two kinds of weighted matrices in Riccati differential equation. What's more, the crossover and mutation probabilities are adaptively computed in the process of AGA. The numeric simulation indicated that the proposed method can effectively control vessel rudder with the satisfactory robustness.

High frequency transformer (HFT) is the key component in bi-directional high-power DC-DC converter stage, which will substitute the traditional bulky transformers for modern power system. This paper presents an optimization design methodology of HFT based on multiobjective genetic algorithm (MOGA) with emphasis on efficiency, power density and thermal behavior. Accurate analytical models on total loss, magnetic size and the maximum temperature rise are carefully discussed and formulated as respective cost functions during optimization. An equivalent thermal model is introduced and validated by finite element modeling (FEM) and computational fluid dynamics (CFD) simulation. Incorporating the proposed methodology, optimal design of a 6kW, 50kHz, 600V/600V, HFT design has been derived, which exhibits a 99.62% efficiency and 12.24 kW/L power density with maximum 54.59°C temperature rise. To verify the effectiveness and accuracy of the analytical expressions employed in the optimization methodology, experiments were performed on the constructed prototype and the analytical models have been well benchmarked with the laboratory results.

Medium-frequency (MF) transformer has gained much popularity in power conversion systems. Temperature control is a paramount concern, as the unexpected high temperature declines the safety and life expectancy of transformer. The scrutiny of losses and thermal-fluid behavior are thereby critical for the design of MF transformers. This paper proposes a coupled, semi-numerical model for electromagnetic and thermal-fluid analysis of MF oil natural air natural (ONAN) transformer. An analytical model that is based on spatial distribution of flux density and AC factor is exploited to calculate the system losses, while the thermal-hydraulic behavior is modelled numerically leveraging the computational fluid dynamics (CFD) method. A close-loop iterative framework is formulated by coupling the analytical model-based electromagnetic analysis and CFD-based thermal-fluid analysis to address the temperature dependence. Experiments are performed on two transformer prototypes with different conductor types and physical geometries for validation purpose. Results suggest that the proposed model can accurately model the AC effects, losses, and the temperature rises at different system components. The proposed model is computationally more efficient than the full numerical method but it reserves accurate thermal-hydraulic characterization, thus it is promising for engineering utilization. Published version

Nowadays, medium frequency transformers are widely employed with power electronic converters, offering obvious benefits for modern power system. Rising the switching frequency leads to the need for accurate estimation of the characteristics of a designed transformer. This paper refines the existing analytical frequency-dependent method for accurately calculating leakage inductance in the medium frequency range based on the magnetic field intensity distribution and the stored magnetic energy method. Unlike the previous expressions, the proposed method employs mean turn length of individual layer which makes the calculation more precise. The advantages and impacts of interleaved winding structure to minimize the leakage inductance are also shown by comparing different winding patterns. Transformer prototypes with specifications as 10kW, 500/5000V, 5kHz have been manufactured and tested. The presented equations for inductance calculation are benchmarked to the experimental results on the developed transformer prototypes as well as the finite element analysis (FEM) simulation results.

The maximum current carrying capacity of a power cable (Ampacity) is determined by the thermal characteristics of the cable components and surrounding medium in which they are buried. Power cable ampacity calculations are based on typical standard tables defined with predetermined parameters. In realtime, the environment of installation plays significant role in cable current carrying capacity. This paper presents FEM approach to determine the maximum current capacity within the safe operating limits of the cable by modeling electro-magnetic heat transfer. The study includes complex thermo-electric coupling and heat transfer in different zones surrounding the cable and its effect on the conductor operating temperature. The results show the difference between the proposed approach and standard calculations and improvements to accurate rating of the cables.

Nowadays, medium frequency transformers have gained growing attention in modern power system. Higher power density, which is realized by increasing the operating frequency, leads to the reduction of the magnetic components size. Along with it, cooling surface is consequently reduced which results in high thermal stress. Careful attention must be paid on the loss mechanisms and thermal analysis of a medium frequency transformer at the design stage. This paper develops an equivalent thermal circuit of an oil-immersed medium frequency transformer to predict its temperature profile. Thermal resistance, capacitance and the losses generated in the core and winding are carefully estimated. Two oil-immersed shell-type transformer prototypes with specifications as 5kW, 500/5000V, 5kHz, interleaved winding construction have been developed and built for verification purpose. Loss and temperature measurements have been performed to verify the presented framework. The accuracy of the proposed thermal model is benchmarked and corroborated through experimental measurements as well as FEM-CFD study with good agreement.

To find balance among multiple design objectives of a medium/high-frequency (MF/HF) high-power (HP) transformer is best addressed employing an optimization technique. In this paper, MF HP transformer design is formulated as a multi-variable optimization problem, where efficiency, power density and temperature rise are chosen as design objectives. Total loss, core volume and maximum temperature rise are modeled as respective cost functions and amalgamated using weighted-sum approach to derive objective function. It is minimized using Steepest descent method. Being a gradient-based search technique, it preserves correlation among design variables during minimization. Using the proposed methodology, optimal design of a 10 kW, 0.5/5 kV, 1 kHz natural oil-cooled transformer with amorphous core and concentric foil winding, is derived. It is estimated to have an efficiency of 99.55% at a power density of 19.79 and maximum node temperature of 52.92 °C. These merit of figures are validated using FEM and CFD studies. Cost-effectiveness of proposed methodology is discussed with the help of a hardware prototype, built from off-the-shelf amorphous core. Benefits like design flexibilities and plausible cost-effectiveness, are inherent to gradient-based optimization method, which augur well for its applicability for MF HP transformer design.

A medium/high-power conversion system using power electronic (PE) converter along with a medium/high-frequency transformer, offers many desirable features that are beneficial for present-day power system topologies. Leakage inductance is identified to be one of the key parameters to characterize performances of such a medium-frequency (MF) high-power (HP) transformer. In this paper, existing analytical method to calculate leakage inductance of a concentric winding is further refined employing mean turn length of individual layer and winding porosity factor. Impact of interleaving to reduce leakage inductance is studied. Consequently different winding dispositions (normal and interleaved) and conductor geometries (foil, round) are investigated for a 10 kW, 0.5/2.5 kV, 1 kHz transformer design. Finally generalized method to deduce leakage inductance of fractional-interleaved winding is introduced in scope of this paper. Analytical calculations are corroborated with PEMag simulation results. With proper selection of wire and core geometry, good agreement between analytical and PEMag results is achieved at medium switching frequency, which substantiates aptness of presented methodology.

Medium/high-frequency transformer is an integral part of many power conversion systems. Switching at higher frequency results in lesser volume of magnetics but induces higher winding loss density, on account of increased eddy current effects in conductors. Thus winding resistance is a key parameter to characterize performance of a medium-frequency (MF) highpower (HP) transformer. In this paper, 10 kW, 0.5/2.5 kV, 1 kHz transformer designs are presented employing different winding dispositions (normal and interleaved) and conductor geometries (foil, round). Dowells' and Ferreira's methods, which are computationally cost-effective among other analytical methods, are discussed to calculate winding resistance at higher switching frequency. Nature of ac resistance factor distribution among multi-layer winding is examined in detail and shown that with adaption of interleaved winding, eddy-current effects at higher switching frequency is minimized. Analytically calculated results are validated with FEA (2D) simulation. At medium frequency, with proper selection of core and winding geometry, very close agreement is achieved between analytical and FEA (2D) results, which substantiates aptness and computational efficacy of Dowell's and Ferreira's methods as well as aiding effect of interleaving to reduce ac resistance in multi-layer wining.

A medium/high-power conversion system, using power electronic (PE) converter in conjunction with a medium/high-frequency transformer, has many desirable effects suitably oriented for modern power system architecture. Switching at high frequency results in lesser volume of magnetics but induces higher loss density. Thus design and characterization of a medium-frequency (MF) high-power (HP) transformer has significant ramification on its performance and application. Thermal management of a MF HP transformer is one of key aspects for its characterization. In this paper, an equivalent thermal model of a multi-layer concentrated winding is derived. Core and copper losses are carefully estimated. Thermal resistance and capacitance are accurately calculated. Time-domain response of proposed thermal network is obtained using Heun's method (Modified Euler) and validated with PLECS. Effects of temperature change on thermal properties of material and coolant (transformer oil) are also discussed. Furthermore, accuracy of said thermal network is corroborated through FEM-CFD study of a 10kW, 0.5/2.5kV, 1kHz natural oil-cooled transformer. Close agreement between analytical and simulation results is observed which substantiates proposed thermal model in terms of accuracy and efficacy of computation.

The blade vibration of the wind turbine is mainly caused by the natural vibration of the blade, the random vibration of the wind and vibration of the bearing of the input side. Collecting vibration wave on the blade and surrounding, then separate the independent waveforms from the collected waveforms by fixed point fast separation (Fast ICA) algorithm, finally, make analysis of the spectrum of the independent waves through the fast Fourier.