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Taking the actual vehicle magneto-rheological (MR) semi-active suspension system as research object, a novel parallel coordinating control strategy for vehicle semi-active suspension system was proposed on the basis of considering movements features in vertical, rolling and pitching directions, respectively. In solving the output control force of magneto-rheological damper, a reverse BP neural network was imported to obtain a desired mapping relation between output control force and actual input current, so as to guarantee the mutual coordinated accuracy between them. According to different body vibration modes, and through establishing basic domain and constraint condition of body vibration acceleration, PID parameters can be corrected online in real time according to partition rules of fuzzy space of vibration mode, and thus the computing resource required for real-time control can be saved. Numerical calculation results show that under the premise of ensuring driving safety, the control strategy proposed in this paper can reduce body vertical vibration, roll angle and pitch angle amplitude by 15.89%, 12.06%, and 31.07%, respectively. Such method will lay a theoretical basis for further improving ride comfort and handling stability of suspension system. [ABSTRACT FROM AUTHOR]

In order to address the problem that traditional passive suspension damping parameter cannot be adjusted which makes it difficult to improve vehicle ride comfort and handling stability, the paper proposes use of controllable magneto-rheological dampers in replace of passive dampers to establish semi-active suspension based on magneto-rheological dampers. By designing magneto-rheological damper reverse model based on BP neural network, it solves the problem of reverse request of input current required with expected damping force and damper piston relative displacement, forms closed loop feedback system with the inverse model and the designed fuzzy PID controller and achieves semi-active control of vehicle suspension. The experimental results and data analyses of inputting different road excitation in the system show that the intelligent hybrid control method proposed in this paper can effectively improve the vehicle ride comfort and handling stability and improve suspension system performance. This paper conducts comparative analyses of vehicle semi-active suspension system performance for the cases of different speeds on different roads, which further validate rationality and effectiveness of the method. [ABSTRACT FROM AUTHOR]

For unfavorable control effect due to difficult precise modeling of system and complex road conditions in the vehicle semi-active suspension control, this paper proposes a fuzzy PID hybrid control strategy based on generic algorithm optimization. This method codes the fuzzy control rule by using the floating number coding, uses the reciprocal of suspension performance evaluation function as the fitness function of genetic algorithm, and optimizes the fuzzy control rules by using the genetic operations such as probability selection, multipoint crossover and single-point mutation. The numerical computing and analysis indicates that the proposed control strategy can effectively improve performance indexes of body vertical acceleration, suspension dynamic deflection and tyre dynamic load. Compared to the passive suspension, PID-controlled and fuzzy PID-controlled semi-active suspension, the fuzzy PID controlled optimized by the generic algorithm can effectively improve vehicle ride comfort, handling stability and security. [ABSTRACT FROM AUTHOR]

Lidar is an active remote sensing instrument, and it has been widely used in the detection of atmospheric environmental parameters and meteorological parameters. In recent years, climate change has been widely concerned by the public, and the corresponding atmospheric detection technology has also been developed rapidly. Atmospheric Lidar has been developed rapidly in China, and has achieved good research achievements. The research progress and development status of Lidar for atmospheric detection in recent years are introduced and summarized in this invited paper. The advantages and disadvantages of all kinds of atmospheric detection Lidars and their applications in different detection objects are comprehensively introduced in this article. Finally, the bottlenecks of Lidar technology are summarized, and the development trend of Lidar is also prospected. [ABSTRACT FROM AUTHOR]

Lidar and Ka-band Millimeter-Wave Cloud Radar (MMCR) are powerful equipment to detect the height distribution of cloud boundaries, which can monitor the whole life cycle of cloud layers. In this paper, we employ lidar and MMCR to jointly detect cloud boundaries under different conditions (e.g., single-layer clouds, multilayer clouds, and precipitating clouds). By enhancing the echo signal of lidar @1064nm and combining its SNR, he cloud signal can be accurately extracted from the aerosol signals and background noise. The interference signal is eliminated from the power spectrum of the MMCR by using SNRmin and the spectral point continuous threshold, and the quality control of the meteorological signal (echo reflectivity factor) obtained by the inversion is carried out, which improves the detection accuracy of the cloud signal. Based on the advantages and disadvantages of the two devices in detecting cloud boundaries under different conditions, cloud boundary statistical rules are established to analyze the characteristics of cloud boundary changes in Xi'an in 2021. The seasonal variation characteristics of clouds show that the frequency distribution of cloud boundaries in vertical height in spring and summer has a similar variation trend. The normalized cloud amount is the lowest in spring (0.65) and the highest in summer 2.46). The frequency distribution of high-level clouds (at 11~12 km) is the highest in autumn, and the clouds in winter are mainly distributed below 8 km. Furthermore, the cloud boundary frequency distribution results for the whole year of 2021 show that the cloud bottom boundary below 1.5 km is more than 10%, the frequency within the height range of 3.06 km~3.6 km is approximately 3.24%, and the frequency above 8 km is less than 2%. The cloud top boundary frequency distribution has the characteristics of a bimodal distribution. The first narrow peak lies at approximately 1.5~3.1 km, and the second peak appears at 7.5~10.5 km. [ABSTRACT FROM AUTHOR]

To further exploit atmospheres cloud-water resources (CWR), it is necessary to correctly evaluate the amount of CWR in an area. CWR are hydrometeors that have not participated in precipitation formation at the surface and are suspended in the atmosphere to be exploited to maximize possible precipitation in the atmosphere (Zhou, Y., et al. (2020)). CWR includes three items: the existing hydrometeors at a time, the influx of atmospheric hydrometeors along the boundaries of the study area, and the mass of hydrometeors converted from water vapor through condensation or desublimation, defined as condensate. Condensate is the most important part of CWR. At present, there is a lack of effective observation methods for atmospheric column condensates, so the direct observation data of CWR are insufficient. The method for detecting atmospheric column condensate in the atmosphere is proposed and presented. The formation of condensate is closely related to atmospheric meteorological parameters (e.g., temperature and vertical airflow velocity). For stratiform clouds, the amount of atmospheric column condensate can be calculated by the saturated water vapor density and the ascending velocity at the cloud base and top. Active and passive remote sensing technology are applied to detect the mass of atmospheric column condensate. Combining millimetre-wave radar (MWR), lidar and microwave radiometers can well observe the vertical velocity and temperature at the cloud boundary. The detailed detection scheme and data calculation method are presented, and the presented method can realize the deduction of atmospheric column condensate. A case of cloud layer change before precipitation was monitored, and atmospheric column condensate was deduced and obtained. This is the first application, to our knowledge, to operate observations of atmospheric column condensates, which is significant for research on the hydrologic cycle and the assessment of cloud water resources. [ABSTRACT FROM AUTHOR]

A new pure rotational Raman lidar (PRRL) system at a wavelength of 532.25 nm has been designed for profiling the atmospheric temperature of the planetary boundary layer. A newly compact spectroscope structured with three fiber Bragg gratings (FBG) is designed to separate two pure rotational Raman signals for atmospheric temperature retrieval, and to simultaneously block the Mieand Rayleigh-scattering signals with a rejection rate of 107. A numerical simulation shows that the PRRL is capable of profiling the atmospheric temperature and a statistical temperature error less than 1 K is achieved up to a height of 2.0 km and 2.2 km for daytime and nighttime measurement, respectively. [ABSTRACT FROM AUTHOR]

To monitor the variability and the correlation of multiple atmospheric parameters in the whole troposphere and the lower stratosphere, a ground-based ultraviolet multifunctional Raman lidar system was established to simultaneously measure the atmospheric parameters in Xi'an (34.233°N, 108.911°E). A set of dichroic mirrors (DMs) and narrow-band interference filters (IFs) with narrow angles of incidence were utilized to construct a high-efficiency 5-channel polychromator. A series of high-quality data obtained from October 2013 to December 2015 under different weather conditions were used to investigate the functionality of the Raman lidar system and to study the variability of multiple atmospheric parameters in the whole stratosphere. Their conveying characteristics are also investigated using back trajectories with a hybrid single-particle Lagrangian integrated trajectory model (HYSPLIT). The lidar system can be operated efficiently under weather conditions with a cloud backscattering ratio of less than 18 and an atmospheric visibility of 3 km. We observed an obvious temperature inversion phenomenon at the tropopause height of 17–18 km and occasional temperature inversion layers below the boundary layer. The rapidly changing atmospheric water vapor is mostly concentrated at the lower troposphere, below ∼4–5 km, accounting for ∼90% of the total water vapor content at 0.5–10 km. The back trajectory analysis shows that the air flow from the northwest and the west mainly contributes to the transport of aerosols and water vapor over Xi'an. The simultaneous continuous observational results demonstrate the variability and correlation among the multiple atmospheric parameters, and the accumulated water vapor density in the bottom layer causes an increase in the aerosol extinction coefficient and enhances the relative humidity in the early morning. The long-term observations provide a large amount of reliable atmospheric data below the lower stratosphere, and can be used to study their correlation and to improve local climate change research. [ABSTRACT FROM AUTHOR]

In order to enhance the transmission efficiency of wireless power transfer (WPT), a negative permeability metamaterials (NPM) with a structure of honeycomb composed by units of hexagon-shaped spirals copper is proposed in this paper. The unit parameters of the NPM are optimized, to make sure the negative permeability at the special frequency. The S-parameters of the designed NPM are measured by a network analyzer and the permeability is extracted, it shows the honeycomb NPM has a negative permeability at 6.43 MHz. A two-coil WPT is setup and the transmission efficiency of WPT embedded with NPM at the different position and with different structure are investigated. The measured results show that the 2-slab honeycomb NPM have a good perform compared with the 1-slab NPM, and the efficiency can be increased up to 51%. The results show that honeycomb NPM embedded in the WPT help to improve the transmission efficiency remarkable. [ABSTRACT FROM AUTHOR]

• Be different from the existing Mie-scattering slant visibility lidar, a two-wavelength Raman-Mie scanning lidar is proposed slant visibility measurements. • The four-channel spectroscopic system is designed to provide enough aerosol parameter profiles and to obtain 33-layer actual atmospheric scattered radiance. • Vertical lidar and slant lidar are combined to contribute to calculate the slant visibility at any slant directions. • Slant visibility distances are realized with consideration of the interaction of the actual atmospheric scattered radiance and atmospheric transparency. • Lidar experiments under different weather conditions demonstrated the feasibility of the lidar system. Considering the necessity of lidar for atmospheric scattered radiance measurement, and the application scenario in civil aviation airports, an eye-safe two-wavelength Raman-Mie lidar is proposed for slant visibility measurements, which differs from the existing Mie-scattering slant visibility lidar. Lidar system is to provide atmospheric aerosol parameters for SBDART model, so as to solve the calculation of actual atmospheric scattered radiance. The obtained information including the total irradiance, the scattered radiance, and the atmospheric transparency are combined to calculate the contrast ratio between the object and the background.Lidar experiments were carried out over Xi'an University of Technology, China (34.233°N, 108.911°E), and two cases conducted under overcast and haze conditions are investigated. Using the 33-layer atmospheric aerosol list by vertical lidar detection, the 33-layer actual atmospheric scattered radiance and the total solar irradiance are obtained by SBDART model. The atmospheric transparency is further obtained by slant scanning detection. Taking the playground runway and the grassland as the object and the background, the contrast ratio curves can be calculated with consideration of actual atmospheric scattered radiance and atmospheric transparency, and the slant visibility distances can be thus obtained at any slant directions under the contrast ratio of 0.05. The results under overcast condition showed that, the obtained slant visibility is at the distance of 9 km and 11.2 km at a zenith angle of 50° and 70°, with the statistical measurement error of 12.5% and 6.54%. The results under haze weather condition also differs at slant directions, the slant visibility distances varied ranging from 4.4 km to 6.51 km, and the statistical measurement errors are approximately of 10.21% and 8.89%. The results demonstrated the developed two-wavelength Raman-Mie lidar provides a new solution to actual atmospheric scattered radiance measurements, and also validated its feasibility and reliability for accurate slant visibility measurements. [ABSTRACT FROM AUTHOR]

In order to investigate the aerosol variability over the southwest region of Slovenia, an ultraviolet scanning elastic backscatter LiDAR was utilized to make the vertical scan for atmospheric probing. With the assumption of horizontal atmospheric homogeneity, aerosol optical variables were retrieved from the horizontal pixel data points of two-dimensional range-height-indicator (RHI) diagrams by using a multiangle retrieval method, in which optical depth is defined as the slope of the resulting linear function when height is kept constant. To make the data retrieval feasible and precise, a series of key procedures complemented the data processing, including construction of the RHI diagram, correction of Rayleigh scattering, assessment of horizontal atmospheric homogeneity and retrieval of aerosol optical variables. The measurement example demonstrated the feasibility of the ultraviolet scanning elastic backscatter LiDAR in the applications of the retrieval of aerosol extinction and determination of the atmospheric boundary layer height. Three months' data combined with the modeling of air flow trajectories using Hybrid Single Particle Lagrangian Integrated Trajectory Model were analyzed to investigate aerosol variability. The average value of aerosol extinction with the presence of land-based air masses from the European continent was found to be two-times larger than that influenced by marine aerosols from the Mediterranean or Adriatic Sea. [ABSTRACT FROM AUTHOR]

To understand the characteristics of atmospheric pollution in Xi'an, China, the vertical structure of aerosols and meteorological data (temperature and relative humidity) during atmospheric pollution processes were obtained and studied. Lidar and radiosonde data were used for analyses of atmospheric pollution. Polarization lidar was used to study the vertical distribution and optical properties of aerosols during haze and dust processes that occurred in 2015–2016. The planetary boundary layer height (PBLH) and types of aerosol particles were retrieved from polarization lidar. A case study shows that a low PBLH and complex vertical distributions of aerosols, temperature and relative humidity (RH) were the main structural characteristics of haze days. The backscatter coefficient exceeded 0.015 km−1·Sr−1, while the linear particle depolarization ratio was relatively small. A large depolarization ratio above the haze layer, which induces the existence of floating dust, was observed by polarization lidar. Compared with those of haze processes, the vertical aerosol and temperature distributions of dust processes were different. Statistical analyses of the PBLH, temperature inversion, RH and near-surface aerosol concentration were also presented. A lower PBLH, lower average lapse rate of temperature within the PBL, and higher RH were found when haze pollution occurred. An inversion at the top of the boundary layer aggravates ground pollution, while there is not always a temperature inversion when haze occurs in Xi'an. Together, a lower PBLH and lower average lapse rate of temperature weaken the vertical diffusion of pollutants. Decreased vertical diffusion should be the main reason for the formation and persistence of pollution in Xi'an. Increased RH was the catalyst for haze pollution. The aggravation of haze was usually accompanied by an increase in RH, and the decline of haze processes was also accompanied by a decrease or increase (>90%) in RH. • The simultaneous observations of aerosols and meteorological factors profiles in Xi' an, were performed. • The complex vertical distributions of aerosol, temperature and relative humidity were found in pollution process. • Little average lapse rate of temperature is the main reason for the decrease of vertical diffusion ability of pollutants. [ABSTRACT FROM AUTHOR]