Search

Sleep spindles have been implicated in sleep protection, depression and anxiety. However, spindle-related brain imaging mechanism underpinning the deficient sleep protection and emotional regulation in insomnia disorder (ID) remains elusive. The aim of the current study is to investigate the relationship between spindle-related brain activations and sleep quality, symptoms of depression and anxiety in patients with ID. Participants (n = 46, 28 females, 18–60 years) were recruited through advertisements including 16 with ID, according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, and 30 matched controls. Group differences in spindle-related brain activations were analyzed using multimodality data acquired with simultaneous electroencephalography and functional magnetic resonance imaging during sleep. Compared with controls, patients with ID showed significantly decreased bilateral spindle-related brain activations in the cingulate gyrus (familywise error corrected p ˂ 0.05, cluster size 4401 mm3). Activations in the cingulate gyrus were negatively correlated with Pittsburgh Sleep Quality Index scores (r = -0.404, p = 0.005) and Self-Rating Anxiety Scale scores (r = -0.364, p = 0.013), in the pooled sample. These findings underscore the key role of spindle-related brain activations in the cingulate gyrus in subjective sleep quality and emotional regulation in ID.

BackgroundDreams can be affected by recent life events and long-term life experiences. Previous evidence has shown that childhood adverse experiences are associated with sleep quality and dream experiences.ObjectiveThe aim of this study was to explore the relationship between childhood adverse experiences and dream content in adults.Participants and SettingA total of 163 participants without current or past physical or mental disorders aged between 18 and 35 were screened in the hospital. Among them, 120 subjects who completed a dream content record at home and whose anxiety and depression levels and sleep quality were within the normal range were included in the data analysis.MethodsA cross-sectional survey was conducted from June 2017 to December 2019. Dream content for 10 consecutive days was recorded by the participants and coded by the Hall and Van de Castle coding system. Childhood adversity was assessed by the Childhood Trauma Questionnaire (CTQ). In the end, 719 dreams out of 626 nights for 120 participants (44 female) were included in the data analysis, gender differences between groups were analyzed usingt-tests orUtests, and Spearman’s partial correlation and multiple linear regression were used to investigate the relationship between childhood trauma and dream content.ResultsChildhood adversity was associated with characters, friendly interactions, and objects in dream content. Regression models of childhood adversity predicting characters and objects in dream content were constructed. There were no gender differences in general demographic data, sleep quality, emotional state, childhood adversity, dream recall frequency, or dream content.ConclusionChildhood adversity is associated with adult dream content.

Sleep spindles have been implicated in sleep protection, depression and anxiety. However, spindle-related brain imaging mechanism underpinning the deficient sleep protection and emotional regulation in insomnia disorder (ID) remains elusive. The aim of the current study is to investigate the relationship between spindle-related brain activations and sleep quality, symptoms of depression and anxiety in patients with ID. Participants (n = 46, 28 females, 18-60 years) were recruited through advertisements including 16 with ID, according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, and 30 matched controls. Group differences in spindle-related brain activations were analyzed using multimodality data acquired with simultaneous electroencephalography and functional magnetic resonance imaging during sleep. Compared with controls, patients with ID showed significantly decreased bilateral spindle-related brain activations in the cingulate gyrus (familywise error corrected p ˂ 0.05, cluster size 4401 mm

This paper develops a simplified small signal modeling method for 4:1 STC, advancing the implementation of the closed-loop control of PPVR-STC. The mathematical description of the transfer function is deduced, and the model solves the problem that the transfer function of the 4:1 STC precise model is too complicated when applied to PPVR-STC. Besides, the accuracy of the simplified model is verified through the comparison between the bode figures of the small-signal equivalent circuit with that generated by sweeping the PPVR-STC circuit.

LLC resonant converter has been widely applicated due to its advantages over other converters. Multiphase parallel LLC resonant converter is necessary in low voltage and large current condition, however, there is a difficulty lying in current sharing. The small tolerance in the resonant tank may cause the larger current imbalance of the multi phases. This paper proposes a control strategy for parallel LLC resonant converter based on sigma converter regulated by PWM controller, which can solve load-sharing problem. The current sharing of each phase is achieved by balancing the output current of Buck. Moreover, LLC-DCX (DC Transformer) of each phase handles most of the energy, the high efficiency is guaranteed. A 200W two-phase parallel sigma converter is given, the simulation results show that the proposed control method can reduce the imbalance of output current significantly within the full load range, verifying the current sharing control strategy effective.

Sleep spindles have been implicated in sleep protection, depression and anxiety. However, spindle-related brain imaging mechanism underpinning the deficient sleep protection and emotional regulation in insomnia disorder (ID) remains elusive. The aim of the current study is to investigate the relationship between spindle-related brain activations and sleep quality, symptoms of depression and anxiety in patients with ID. Participants (n = 46, 29 females, 18–60 years) were recruited through advertisements including 16 with ID, according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, and 30 matched controls. Group differences in spindle-related brain activations were analyzed using multimodality data acquired with simultaneous electroencephalography and functional magnetic resonance imaging during sleep. Compared with controls, patients with ID showed significantly decreased bilateral spindle-related brain activations in the cingulate gyrus (familywise error corrected p ˂ 0.05, cluster size 3834 mm3). Activations in the cingulate gyrus were negatively correlated with Self-Rating Depression Scale scores (r = -0.454, p = 0.002), Self-Rating Anxiety Scale scores (r = -0.362, p = 0.014) and subjective sleep onset latency (r = -0.374, p = 0.010), while positively correlated with subjective total sleep time (r = 0.343, p = 0.020), in the pooled sample. Besides, activations in the cingulate gyrus were negatively correlated with scores on the Self-Rating Depression Scale (r = -0.650, p = 0.006), in the ID group. These findings underscore the key role of spindle-related brain activations in the cingulate gyrus in subjective sleep quality and emotional regulation in ID.

Based on the full-bridge LLC converter, this paper proposes a hybrid control strategy for input voltage fluctuations. The specific control strategy is as follows: 1) When the input voltage is stable, the PID controller is used. Combine the FM control working mode with the phase shift control working mode; 2) When the input voltage fluctuates, the digital direct controller is used. By direct frequency modulation or direct phase shift control, the fluctuation of the resonant current and the resonant capacitor voltage is reduced, and the output voltage is quickly adjusted.

In order to better control the closed-loop control of Switched Tank Converter with Partial Power Voltage Regulation (PPVR-STC), this paper proposes a small signal modeling method for two kinds of PPVR-STC, which based on the working principle of PPVR-STC and through a series of simplifications. The accuracy of the small signal model is verified by comparing the bode figures obtained by sweeping the frequency of the simulation circuits with the bode figures of the small signal equivalent circuits after simplification, which provides a theoretical basis for closed-loop control.

From the three processes of recycling, remanufacturing and remanufacturing product sales, this paper analyses the characteristics of the automobile engine cost. By using the theory of system dynamics method, it establishes system flow diagram of automobile engine recycling and remanufacturing cost under the methods of network recovery and 4S shop recovery, and constructs engine remanufacturing cost model. Taking Shandong heavy-duty automobile diesel engine remanufacturing as an example, the model is simulated and analyzed with Vensim PLE software, and the change trend of engine recovery cost and profit from 2015 to 2035 is analyzed and predicted. The sales revenue, cost and profit of remanufacturing under the two recovery methods are compared and analyzed. Furthermore, the simulation results show that the different selections of engine recovery strategies have significant differences on the economic impact of engine remanufacturing, and the economic analysis can provide a reference for the development decision of engine remanufacturing.

Engine is the core of auto parts. It has great economic and social benefits for retired engines and their parts by remanufacturing. However, in recycling process, the uncertainty of quality status of retired engines leads to the uncertainty of life cycle cost, which makes it difficult for technicians to evaluate the cost. In order to address the problem mentioned, this study sets up a nonlinear model between the life cycle cost, service time and the quality level of used engine parts by considering damage degree in recycling process of used engine parts as a research index and takes 50 heavy-duty engine connecting rods as an example, which provides a theoretical basis for remanufacturing enterprises to evaluate the cost and determine the remanufacturing process accurately.

Rapid eye movement (REM) sleep has been frequently associated with dreaming. However, mounting evidence obtained from behavioral, pharmacological, and brain imaging studies suggests that REM sleep is not indicative of the dream report and may originate from diverse neural substrates in brain functionality. The aim of the current study was to investigate the functional systems associated with inter-individual differences in dream recall and REM sleep through assessments of the resting-state functional connectivity. We collected resting-state functional magnetic resonance imaging (fMRI) data for functional connectivity evaluations from 43 healthy adult volunteers (23 men) before and after sleep. For assessment of the dream recall frequency, a 2-week sleep diary was maintained by all volunteers. In addition, whole-night polysomnography was performed for measuring the REM sleep percentage. Voxel-wise correlation analyses of 12 functional connectivity networks of interest with the dream recall frequency and REM sleep percentage were conducted using general linear model analysis. Both the dream recall frequency and REM sleep percentage showed negative associations with multiple brain functional networks. However, the dream recall frequency was mainly related to functional connectivity within the lateral visual network and thalamus, whereas the REM sleep percentage was mainly associated with connectivity within the frontoparietal networks and cerebellum. In addition, the dream recall frequency showed stronger coupling with the lateral visual network connectivity at night, whereas the coupling between the REM sleep percentage and cerebellum was higher in the morning. This indicated a significant time of day effect. Our results provide neuroimaging evidence that the functional system associated with the dream recall frequency is different from that associated with the REM sleep percentage.

The airborne laser scanning (ALS) has become the most effective way to acquire 3D information of the earth's surface. However, data post-processing lags far behind hardware especially the filtering algorithm. At present, most algorithms for DEM generation are based on the mutation of the elevation, and every method has its own defects. All of the existing filter algorithms are based on a priori information, so that the accuracy of the filtering is affected by the terrain fluctuation. In this paper, a new algorithm called Hybrid Filtering of Lidar Data based on the Echoes was proposed. First, we make an analysis of echo characteristic of airborne Lidar data, and propose classification schemas based on the characteristic of echo characteristic. Then we use the Pseudo Grid for segmentation and index. Furthermore, using the existing filtering algorithm to distinguish the seed point is terrain point or not. At last, we filter the cooked data. In theory, because of removing part of object point the accuracy and the efficiency must be significantly increased. Experiments show that it is effectively to eliminate most of vegetation and building points, that means, the method proposed in this paper not only can reduce the amount of computing data, but also improve the effect of filtering algorithm for eliminating the building and vegetation.

The parallel inverters without control interconnections was focused. The model of inverter was constructed, and the parameters of LC output filter was designed and tested by simulation. The simulation model of three-phase wireless parallel inverter system was established by MATLAB based on PQ droop algorithm, and the simulation results show that the system has a good effection of current sharing, and both dynamic and steady performance of the system.

The quality of grid-connected current is an important index to measure the performance of grid-connected inverter, rapid and accurate detection of the grid frequency and phase is the premise of the grid-connected current control. A method of the frequency-locked loop (FLL) based on improved reduced order generalized integrator (here called ROGI-FLL) is proposed based on the present FLL technology in this paper, which is able to extract the positive and negative sequence components of the grid voltage and frequency under the condition of unbalanced grid, harmonic distortion, direct current offset and so on. The ROGI-FLL method is used in the grid-connected current control strategy without phase-locked loop, finally the feasibility and effectiveness of this method are verified by simulation and experiment.

Based on the harmonic suppression of grid-connected inverter, it is suggested to use LCL filter instead of traditional L filter. First, it establishes a mathematic model based on LCL filter of PV grid-connected inverter, Then it analyses the function of LCL filter and the advantage of LCL filter based on the response characteristic of LCL filter and L filter. Second, This paper proposes detailed methods for selecting the parameters of LCL filter based on analysis the effect factor of LCL filter so that an optimized performance can be achieved, Third, This paper probes into the influence of sample current's position on system stability, In addition, this paper proposed an improved passive damping which make the system have a smaller losses and more stable. It concludes that by adopting double-loop control which sample inverter-side current as inner loop, sample dc-voltage as outer loop to ensure the stability of system and suppress harmonic efficient. Finally, This paper certifies the feasibility and validity.

In this paper, a small-power brushless DC motor (BLDCM) drive controller with a compensation network is proposed. Firstly, this paper introduces the system dynamic mathematical model. By analyzing its dynamic stability, an improved method is proposed. It's used to compensate the regulator in order to enhance the system dynamic stability. Then, a speed closed-loop controller of BLDCM is designed, which is based on the professional control chip MC33035, the electronic tachometer chip MC33039, and the compensation network. Finally, the experimental results prove that with the contribution of this compensation network, the dynamic performance of this system is indeed improved. Functions such as starting, braking, reversion are accomplished. Motor runs smoothly with low noise, high efficiency, and the applications has become more and more extensive.

Groundwater source heat pump system has great impact on the temperature of groundwater for a long-term. According to the continuity equations, motion equations and energy equations of fluid cylindrical coordinate system and the boundary conditions of pumping production and injection well, the forced convection in turbulent flows model of smooth cylinder has been established. Consider three ways of heat transfer, the inside wall of cylinder based on solid heat conduction theory and the other parts of the drill based on fluid convective heat transfer. Using COMSOL Multiphysics software to analyze the model simulation. Theory and example show that this model can be applied in the simulation of groundwater source heat pump temperature field by the setting of material, bound and mesh.

This paper presents the energy conversion optimization control strategy for a horizontal axis variable speed fixed pitch wind energy conversion system, which works in the partial load region. The system uses a variable speed wind turbine (VSWT), driving a squirrel-cage induction generator (SCIG) connected to a grid. Reference to the wind turbine model and its parameters are poorly known, so a new Maximum Power Point Tracking (MPPT) method is proposed based on the extremum seeking control principles. The aim is to drive the average position of the operating point near optimality. Here, the wind turbulence is used as search disturbance instead of inducing new sinusoidal search signals. The Fast Fourier Transform (FFT) processing of some available measures estimate the operating point's distance to optimality. The effectiveness of the proposed MPPT scheme is validated under different operating conditions by numerical simulations. The simulation results prove that this new approach has effectively suppressed the system vibration and enhanced system dynamic performance.

In order to improve the reliability of chemical equipments operation, the simulation research on the reliability of the operators is needed. Basing on the research platform of Dalian Chemical Industry Group Corporation (The Group), taking the reliability model of Human Cognition Reliability (HCR) as guide, in allusion to the 17 abnormal events which affect the running safety, the allowable operation time and the non-response time of the operators are video-recorded and analyzed. According to the indexes system of International Atomic Energy Agency (IAEA), various errors in operation and their potential harms are sorted out. Based on the three-parameter Weibull model, the non-response probability model is deduced. The countermeasures to prevent accidents are worked out from view of human factor engineering. The results show that the model of human error in operation basing on HCR is available.

With the analysis to the research actuality and its problems to regional safety risk assessment at home and abroad, a method of regional safety risk assessment for Urban Chemical Industrial Park with multi-danger source is put forward. Firstly, the assessed region is carved up into series of two dimensional square grids in equal Stride length mesh based on grid partition method. Secondly, making use of the information diffusion method, the probabilities of fire and explosion in park are calculated based on the statistic data of Dalian city. At the same times, the severity degrees of the results of accidents are analyzed based on the model of Boiling Liquid Expanding Vapor Explosion (BLEVE), and then the injury ranges of the death, the severe injured and the mild injury have been transformed into the probability of individual death. Thirdly, the individual safety risk values in center of the grids are calculated according to the superposition principle of risks, and the social safety risks are assessed founded on the Complementary Cumulative Distribution Function (CCDF). Finally, the distribution maps of the individual safety risk and social safety risk are drawn according to the interpolation functions, and the practice model is provided.

The fixed-pitch wind turbines have simple structure and lower cost, which change the output power mainly depending on the stall characteristics of the blades when the speeds of the turbine is constant. To increase the output power of the turbines, the variable speeds running in deep stall regime should be researched. Fixed-pitch variable speed wind turbines can be operated not only for MPPT in low wind speeds but also for constant power control in high wind speeds with the speed control system, thus the fixed-pitch wind turbines have the power characteristics as that of the pitch-controlled wind turbines. The robust PID controller is designed for speed control system. The further analysis shows that the speed control system with the PID controller designed has good robustness under different wind conditions. The fixed-pitch variable speed wind turbine can be operated stably in operating wind speeds and the speed controller has good dynamic characteristics, which indicate that the fixed-pitch variable speed wind turbine can be operated not only for MPPT in low wind speeds but also for constant power control in high wind speeds.

Considering the characteristics of fixed-pitch variable-speed wind turbine operating in all operating wind speed, the small signal model was established, which indicates that the system is unstable in high wind speed. In this paper, the use of disturbance observer for aerodynamic torque estimation and compensation was presented, which is to eliminate the unstable factors in the system itself and make the system into a stable linear system. And then the speed control system was designed based on the RT-LAB real time simulation system. The results show that the fixed-pitch variable speed wind turbines can be operated stably in all operating wind speed and the speed control system have good at tracking changing wind velocity, which indicated that fixed-pitch variable speed wind turbine can be operated not only for MPPT in low wind speed but also for constant power control in high wind speed.

Method for wind turbine controller design and test in laboratory still remains a problem. This paper presents a realtime simulator of non-grid-connected wind energy conversion system suitable for controller design and test. The simulation model, which is composed of a fixed-pitch wind turbine, a permanent magnet synchronous generator with PWM voltage source vector control and DC-DC converter with peak current control, is especially suitable for electrochemical industries. High energy efficiency can be achieved by adjusting the rotor speed according to the wind speed. Simulation results show the validity of system modeling and control strategy.

Dedicated to high energy-consuming industries, such as chloral-alkali, seawater desalination, and electrolytic aluminum, a novel non-grid-connected power generation (NGCPG) system is proposed; it is composed of a fixed-pitch variable speed wind turbine and a doubly salient DC brushless generator. The configuration of the non-grid-connected power system mentioned is presented. An equivalent model of the system is built based on analyzing and modeling each component. The control strategy, controlling the turbine speed by regulating load current based on turbine Cp-λ curves, turbine torque curve and doubly salient generator electromagnetic torque characteristic, is proposed. The performance is as good as a variable-pitch wind turbine system can be achieved for such a fixed-pitch variable speed system mentioned with the control. System stability is analyzed with the proposed stable region, dT a /dw less thandT a /dw. Simulation results are given to verify the analysis.

Wind power industry has become an important strategy to alleviate supply shortage of power. Compared with net-grid-connected wind power system, it is one of the effective ways to reduce construction cost and no-fluctuation to the grid by directly applying the large-scale wind power to high energy-consuming industries. So it is an effective and economical approach to increase the proportion of wind power in China's energy structure, and we call this new system “non- net-grid-connected wind power system”. This paper introduced the composition of the Non-grid-connection Wind Power System, provided the structure program of wind power generation system with flywheel energy storage battery, then introduced the HVDC Light Transmission Technology adopted in this system, and pointed out the high input voltage was the main challenge of high power DC-DC converter. After reviewing the main solutions of input-voltage sharing of the high voltage DC-DC converters, a novel equal input-voltage sharing strategy of input-series output-parallel (ISOP) converter was presented. This strategy was designed to solve input-voltage unbalancing at light load. In the end, simulation results were presented to show the effectiveness of this control method.

In view of the characteristic that the effect of controlling respirable dust is very poor in current mines. This text analyzes some characteristics of dust and some problems in current dedusting technology, which introduces several new dedusting technologies that are more suitable for mine. These dedusting technologies can achieve good result to respiratory dust and create a good working environment for miners.

The common disposal methods for acceptable urban solid waste (USW) in China are open dump and sanitary landfill, which will definitely bring problems like environmental pollution, resource waste and land occupation etc.. Categorized collection is one of the best way to solve the problems and also the primary prerequisite of resource utilization of the waste. The objective of this study is to carry out a survey of urban solid waste generation and composition from 2004 to 2006 in Shanghai, the most developed city of China. By applying the economic mathematic method, the USW categorized collection model is established, the cost and benefit of the mixed collection and classified collection are analyzed and evaluated. The result shows that it is feasible to collect the USW by classification, which may simplify the waste disposal procedure, improve the resource recovery rate, save social cost and achieve favorable economic returns. In a word, it is a scientific and effective method to realize the quantitative reduction and resource recovery of USW.

A novel wireless parallel control for inverters based on power line communication (PLC) is proposed, where the pre-synchronized control for voltage reference is realized beyond the current distribution control. The PLC modem chip is controlled by digital signal processor (DSP) to realize data transmitting and receiving operations through power line. By means of PLC and DSP algorithm, the frequency and phase of the sinusoidal voltage reference are exchanged and regulated to keep the output of the inverter modules almost in phase to improve output current sharing greatly among the inverters in parallel. Compared to the conventional wireless parallel control based on real and reactive power regulation, the proposed parallel control possesses good transient performance with lower shock during hot-swap operations due to the pre-synchronized reference signal. The synchronization regulation error is also analyzed. Theoretical analysis and experimental results are provided to verify the validity and feasibility of the proposed control.