Structural 3D Reconstruction of Indoor Space for 5G Signal Simulation with Mobile Laser Scanning Point Clouds

3D modelling of indoor environment is essential in smart city applications such as building information modelling (BIM), spatial location application, energy consumption estimation, and signal simulation, etc. Fast and stable reconstruction of 3D models from point clouds has already attracted considerable research interest. However, in the complex indoor environment, automated reconstruction of detailed 3D models still remains a serious challenge. To address these issues, this paper presents a novel method that couples linear structures with three-dimensional geometric surfaces to automatically reconstruct 3D models using point cloud data from mobile laser scanning. In our proposed approach, a fully automatic room segmentation is performed on the unstructured point clouds via multi-label graph cuts with semantic constraints, which can overcome the over-segmentation in the long corridor. Then, the horizontal slices of point clouds with individual room are projected onto the plane to form a binary image, which is followed by line extraction and regularization to generate floorplan lines. The 3D structured models are reconstructed by multi-label graph cuts, which is designed to combine segmented room, line and surface elements as semantic constraints. Finally, this paper proposed a novel application that 5G signal simulation based on the output structural model to aim at determining the optimal location of 5G small base station in a large-scale indoor scene for the future. Four datasets collected using handheld and backpack laser scanning systems in different locations were used to evaluate the proposed method. The results indicate our proposed methodology provides an accurate and efficient reconstruction of detailed structured models from complex indoor scenes

Local Frequency Modulation Strategy Based on Controllable Load Characteristic Identification of Multi-Port Power Router

The scarcity of inertial resources in the new AC–DC hybrid grids makes the grid frequency prone to fluctuation. In this paper, the relationship between the grid-side and load-side characteristics of the power router is constructed. By adjusting the port load parameters, the load power can respond quickly to the fluctuation of the grid frequency, thereby realizing rapid support of the grid frequency. Firstly, two kinds of mathematical models for sensitivity identification of load characteristics, variable voltage and variable frequency, are established to calculate the characteristic parameters of a multi-port load. The allocation rules of port power and allocation coefficients are designed according to the parameters. A frequency modulation control method that matches the load response capability of the multi-port router is proposed. Then, taking into consideration the uncertainty of load group characteristics and power, a variable coefficient frequency modulation control strategy for a multi-port power router that can adapt to the adjustable margin of loads is proposed. The proposed model is built based on a Simulink platform for validation. The simulation results show that the proposed frequency modulation strategy can be added, and the frequency modulation performance of the power grid is further improved compared to the situation without this method. The frequency is suppressed to 49.93 HZ. It is verified that this method can make the controllable load respond sensitively and effectively to grid disturbance

Microstructure and dielectric properties of BZT-BCT/PVDF nanocomposites

In this paper, the 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 nanofibers (BZT-BCT NFs) with high aspect ratio were synthesized by electrospinning technique, and the PVDF-based composites filled with the BT NPs or BZT-BCT NFs were fabricated. Obviously, compared to the BT NPs/PVDF composite, the dielectric properties of BZT-BCT NFs/PVDF composites are improved at given volume fraction. The electric modulus formalism indicated that the BZT-BCT NFs could effectively enhance the interfacial polarization of the BZT-BCT NFs/PVDF composites than that of the BT NPs/PVDF composite. In addition, the BZT-BCT NFs with large aspect ratio can make the composites polarize at a higher field strength, thus the composites obtain higher polarization strength. The energy density of 3 vol% BZT-BCT NFs/PVDF composite is 3.08 J/cm3 at 240 kV/mm, which is 2.01 times higher enhancement than the BT NPs/PVDF composite (1.53 J/cm3 at 180 kV/mm). These results also provide a simple but effective method to achieve the materials with high capacitance for energy storage. Keywords: Powders, Nanocomposites, Interfaces, Dielectric properties, Energy storage densit

Influence of Space Charge on Dielectric Property and Breakdown Strength of Polypropylene Dielectrics under Strong Electric Field

Space charge accumulation in polypropylene (PP) affect the dielectric properties and breakdown strength of the material. The pre-injected charge in PP under the action of different polarity voltage is quantitatively characterized, and the effects of the pre-injected charge inside the dielectric on the dielectric properties and breakdown strength are measured and analyzed. Based on the molecular simulations, the influence mechanism of the temperature on dielectric properties and breakdown are discussed. The experimental results show that the injected charges in PP under the negative polarity voltage is significantly larger than that of the positive polarity. These charges have a great influence on the dielectric constant and breakdown performance of PP, and the effect is different for different charge polarity. The effect of negative polarity pre-voltage conditions on the dielectric constant is much greater than that of positive polarity, and the dielectric constant of PP decreases from 2.2 to 1.3, decreasing about 41% under the negative polarity pre-voltage. By contrast, the dielectric constant slightly increases under the effect of the homopolar preload. Furthermore, the breakdown strength of the dielectric after the heteropolar preload is 249 kV/mm, which is 36% lower than that of PP without pre-voltage, and it slightly increases after the positive polarity pre-voltage. As the temperature increases, the increase in free volume favors the development of electron collision ionization and electron collapse processes, leading to a decrease in breakdown voltage at high temperatures. This work has a good guiding significance for the comprehensive evaluation of energy storage parameters

Evaluation of Airborne LiDAR Bathymetric Parameters on the Northern South China Sea Based on MODIS Data

In order to study the spatial distribution of maximum coastal zone mapping and imaging LiDAR(CZMIL)detectable depth in the northern South China Sea,we firstly research the existing Kd(490) inversion algorithm in the northern South China Sea.The relationship between the diffuse attenuation coefficient Kd(490) and Kd(532) is established based on the optical profile data measured,and the relationship between the diffuse attenuation coefficient Kd(532) and the maximum CZMIL detectable depth is summarized.Then,using the remote measurement data of the Aqua-MODIS,we obtain the spatial distribution of diffuse attenuation coefficient at 532 nm in the northern South China Sea in January,June and October,2014.It shows that June is more suitable for bathymetry operation than in October and January.Finally,we obtain the spatial distribution of maximum CZMIL detectable depth in June in the northern South China Sea.The results show that the CZMIL detectable water depths in the northern South China Sea are about 0~71.18 m.The study provides a reference for the time selection and flight scheme of LiDAR bathymetry operation in the northern South China Sea

Uncovering the Molecular Mechanism of the Qiang-Xin 1 Formula on Sepsis-Induced Cardiac Dysfunction Based on Systems Pharmacology

Cardiac dysfunction is a critical manifestation of sepsis-induced multiorgan failure and results in the high mortality of sepsis. Our previous study demonstrated that a traditional Chinese medicine formula, Qiang-Xin 1 (QX1), ameliorates cardiac tissue damage in septic mice; however, the underlying pharmacology mechanism remains to be elucidated. The present study was aimed at clarifying the protective mechanism of the QX1 formula on sepsis-induced cardiac dysfunction. The moderate sepsis model of mice was established by cecal ligation and puncture surgery. Treatment with the QX1 formula improved the 7-day survival outcome, attenuated cardiac dysfunction, and ameliorated the disruption of myocardial structure in septic mice. Subsequent systems pharmacology analysis found that 63 bioactive compounds and the related 79 candidate target proteins were screened from the QX1 formula. The network analysis showed that the QX1 active components quercetin, formononetin, kaempferol, taxifolin, cryptotanshinone, and tanshinone IIA had a good binding activity with screened targets. The integrating pathway analysis indicated the calcium, PI3K/AKT, MAPK, and Toll-like receptor signaling pathways may be involved in the protective effect of the QX1 formula on sepsis-induced cardiac dysfunction. Further, experimental validation showed that the QX1 formula inhibited the activity of calcium/calmodulin-dependent protein kinase II (CaMKII), MAPK (P38, ERK1/2, and JNK), and TLR4/NF-κB signaling pathways but promoted the activation of the PI3K/AKT pathway. A cytokine array found that the QX1 formula attenuated sepsis-induced upregulated levels of serum IFN-γ, IL-1β, IL-3, IL-6, IL-17, IL-4, IL-10, and TNF-α. Our data suggested that QX1 may represent a novel therapeutic strategy for sepsis by suppressing the activity of calcium, MAPK, and TLR4/NF-κB pathways, but promoting the activation of AKT, thus controlling cytokine storm and regulating immune balance. The present study demonstrated the multicomponent, multitarget, and multipathway characteristics of the QX1 formula and provided a novel understanding of the QX1 formula in the clinical application on cardiac dysfunction-related diseases

A Triangular Prism Spatial Interpolation Method for Mapping Geological Property Fields

Abstract: The spatial interpolation of property fields in 3D, such as the temperature, salinity, and organic content of ocean water, is an active area of research in the applied geosciences. Conventional interpolation methods have not adequately addressed anisotropy in these data. Thus, in our research we considered two interpolation methods based on a triangular prism volume element, as a triangular prism structure best represents directivity, to express the anisotropy inherent in geological property fields. A linear triangular prism interpolation is proposed for layered stratum that achieves a complete continuity based on the volume coordinates of the triangular prism. A triangular prism quadric interpolation (a unit function of a triangular prism spline with 15 nodes) is designed for a smooth transition between adjacent triangular prisms with approximately continuity, expressing the continuity of the entire model. We designed a specific model which accounts for the different spatial correlations in three dimensions. We evaluated the accuracy of our proposed linear and triangular prism quadric interpolation methods with traditional inverse distance weighting (IDW) and kriging interpolation approaches in comparative experiments. The results show that, in 3D geological modeling, the linear and quadric triangular prism interpolations more accurately represent the changes in the property values of the layered strata than the IDW and kriging interpolation methods. Furthermore, the triangular prism quadric interpolation algorithm with 15 nodes outperforms the other methods. This study of triangular prism interpolation algorithms has implications for the expression of data fields with 3D properties. Moreover, our novel approach will contribute to spatial attribute prediction and representation and is applicable to all 3D geographic information; for example, in studies of atmospheric circulation, ocean circulation, water temperature, salinity, and three-dimensional pollutant diffusion