Development of a New Beam-Column Design Method for Cold-Formed Steel Lipped Channel Members

The structural strength of cold-formed steel lipped channels under combined axial force and biaxial bending moments has been predicted by geometric and material nonlinear collapse analyses performed in ABAQUS and compared to both current, and a newly proposed, beam-column design method. The ABAQUS analyses utilizes a validated modeling protocol calibrated against previous testing by the authors, and including residual stresses and strains, and geometric imperfections; as well as, appropriate cross-section dimensions, member length, and boundary conditions. A total of 75 different lipped channel cross-sections have been selected and the capacity of the beam-column member has been examined under 127 combinations of actions in the P-M1-M2 space (axial load, P, and major-axis, M1, and minor-axis, M2, bending moments). The results have been used to evaluate the current beam-column design method and validate a new Direct Strength Method (DSM) approach for cold-formed steel beam-columns. The newly proposed method provides means to incorporate more realistic stability analyses of cross-sections under the applied actions, where the current design methods include only a linear prediction of the combined actions using “column strength” and “beam strength” as anchor points. Correspondingly, the reliability of both current and newly proposed methods has been evaluated. The newly proposed extensions to the Direct Strength Method show a potential to realize a sizeable strength increase in many situations, and follow the overall trends in the data (P-M1-M2 surface) well; however, additional advancement is needed to realize the complete benefits predicted in the finite element models

Linkage between surface energy balance non‐closure and horizontal asymmetric turbulent transport

A number of studies have reported that the traditional eddy covariance (EC) method generally underestimated vertical turbulent fluxes, leading to an outstanding non-closure problem of the surface energy balance (SEB). Although it is recognized that the enlarged surface energy imbalance frequently coincides with the increasing wind shear, the role of large eddies in affecting the SEB remains unclear. On analyzing data collected by an EC array, considerable horizontal inhomogeneity of kinematic heat flux is observed. The results show that the combined EC method that incorporates the spatial flux contribution increases the kinematic heat flux by 21% relative to the traditional EC method, improving the SEB closure. Additionally, spectral analysis indicates that large eddies with scales ranging from 0.0005 to 0.01 (in the normalized frequency) mainly account for the horizontal inhomogeneity of kinematic heat flux. Under unstable conditions, this process is operating upon large eddies characterized by enlarged asymmetric turbulent flux transport. With enhanced wind shear, the increment of flux contribution associated with sweeps and ejections becomes disproportionate, contributing to the horizontal inhomogeneity of kinematic heat flux, and thus may explain the increased SEB non-closure

Development of an UAS for Earthquake Emergency Response and Its Application in Two Disastrous Earthquakes

To support humanitarian action after a disaster, we require reliable data like high-resolution satellite images for analyses aimed to define the damages of facilities and/or infrastructures. However, we cannot obtain satellite images in few days after an event. Thus, in situ surveys are preferred. Advances in unmanned aircraft system (UAS) have promoted them to become precious tools for capturing and assessing the extents and volume of damages. Safety, flexibility, low cost, and ease of operation make UAS suitable for disaster assessment. In this chapter, we developed an example of UAS for swiftly acquiring disaster information. With the selected fixed-wing UAS, we successfully performed data acquisition at specified scales. For the image analysis, we applied a photogrammetric workflow to deal with the very high resolution of the images obtained without ground control points. The results obtained from two destructive earthquakes demonstrated that the presented system plays a key role on the processes of investigating and gathering information about a disaster in the earthquake epicentral areas, like road detection, structural damage survey, secondary disaster investigation, and quick disaster assessment. It can effectively provide disaster information in hardly entered areas to salvation headquarters for rapidly developing the relief measures

An Integrated Visual Analytics System for Studying Clinical Carotid Artery Plaques

Carotid artery plaques can cause arterial vascular diseases such as stroke and myocardial infarction, posing a severe threat to human life. However, the current clinical examination mainly relies on a direct assessment by physicians of patients' clinical indicators and medical images, lacking an integrated visualization tool for analyzing the influencing factors and composition of carotid artery plaques. We have designed an intelligent carotid artery plaque visual analysis system for vascular surgery experts to comprehensively analyze the clinical physiological and imaging indicators of carotid artery diseases. The system mainly includes two functions: First, it displays the correlation between carotid artery plaque and various factors through a series of information visualization methods and integrates the analysis of patient physiological indicator data. Second, it enhances the interface guidance analysis of the inherent correlation between the components of carotid artery plaque through machine learning and displays the spatial distribution of the plaque on medical images. Additionally, we conducted two case studies on carotid artery plaques using real data obtained from a hospital, and the results indicate that our designed carotid analysis system can effectively provide clinical diagnosis and treatment guidance for vascular surgeons

An Efficient Data Collection Protocol Based on Multihop Routing and Single-Node Cooperation in Wireless Sensor Networks

Considering the constrained resource and energy in wireless sensor networks, an efficient data collection protocol named ESCDD which adopts the multihop routing technology and the single-node selection cooperative communication is proposed to make the communication protocol more simple and easy to realize for the large-scale multihop wireless sensor networks. ESCDD uses the greedy strategy and the control information based on RTS/CTS to select forwarding nodes. Then, the hops in the multihop data transmission are reduced. Based on the power control in physical layer and the control frame called CoTS in MAC layer, ESCDD chooses a single cooperative node to perform cooperative transmission. The receiving node adopts maximal ratio combining (MRC) to recover original data. The energy consumption per hop is reduced. Furthermore, the total energy consumption in data collection process is shared by more nodes and the network lifetime is extended. Compared with GeRaF, EERNFS, and REEFG protocol, the simulation results show that ESCDD can effectively reduce the average delay of multihop data transmission, improve the successful delivery rate of data packets, significantly save the energy consumption of network nodes, and make the energy consumption more balanced

Effects of AMF inoculation on the eco-physiological characteristics of Imperata cylindrica under differing soil nitrogen conditions

Arbuscular mycorrhizal fungi (AMF) play a key role in terrestrial ecosystems, while the ecological restoration application of AMF in mining areas has been progressively gaining attention. This study simulated a low nitrogen (N) environment in copper tailings mining soil to explore inoculative effects of four AMF species on the eco-physiological characteristics of Imperata cylindrica, and provided plant-microbial symbiote with excellent resistance to copper tailings. Results show that N, soil type, AMF species, and associated interactions significantly affected ammonium (NH4  +), nitrate nitrogen (NO3  −), and total nitrogen (TN) content and photosynthetic characteristics of I. cylindrica. Additionally, interactions between soil type and AMF species significantly affected the biomass, plant height, and tiller number of I. cylindrica. Rhizophagus irregularis and Glomus claroideun significantly increased TN and NH4  + content in the belowground components I. cylindrica in non-mineralized sand. Moreover, the inoculation of these two fungi species significantly increased belowground NH4  + content in mineralized sand. The net photosynthetic rate positively correlated to aboveground total carbon (TC) and TN content under the high N and non-mineralized sand treatment. Moreover, Glomus claroideun and Glomus etunicatum inoculation significantly increased both net photosynthetic and water utilization rates, while F. mosseae inoculation significantly increased the transpiration rate under the low N treatment. Additionally, aboveground total sulfur (TS) content positively correlated to the intercellular carbon dioxide (CO2) concentration, stomatal conductance, and the transpiration rate under the low N sand treatment. Furthermore, G. claroideun, G. etunicatum, and F. mosseae inoculation significantly increased aboveground NH4  + and belowground TC content of I. cylindrica, while G. etunicatum significantly increased belowground NH4  + content. Average membership function values of all physiological and ecological I. cylindrica indexes infected with AMF species were higher compared to the control group, while corresponding values of I. cylindrica inoculated with G. claroideun were highest overall. Finally, comprehensive evaluation coefficients were highest under both the low N and high N mineralized sand treatments. This study provides information on microbial resources and plant-microbe symbionts in a copper tailings area, while aiming to improve current nutrient-poor soil conditions and ecological restoration efficiency in copper tailings areas

Water vapor estimation based on 1-year data of E-band millimeter wave link in North China

Abstract. The amount of water vapor in the atmosphere is very small, but its content varies greatly in different humidity areas. The change in water vapor will affect the transmission of microwave link signals, and most of the water vapor is concentrated in the lower layer, so the water vapor density can be measured by the change in the near-ground microwave link transmission signal. This study collected 1-year data of the E-band millimeter wave link in Hebei, China, and used a model based on the International Telecommunication Union Radiocommunication Sector (ITU-R) to estimate the water vapor density. An improved method of extracting the water-vapor-induced attenuation value is also introduced. It has a higher time resolution, and the estimation error is lower than the previous method. In addition, this paper conducts the seasonal analysis of water vapor inversion for the first time. The monthly and seasonal evaluation index results show a high correlation between the retrieved water vapor density and the actual water vapor density value measured by the local weather station. The correlation value for the whole year is up to 0.95, the root mean square error is as low as 0.35 g m−3, and the average relative error is as low as 5.00 %. Compared with European Center for Medium-Range Weather Forecast (ECMWF) reanalysis, the correlation of the daily water vapor density estimation of the link has increased by 0.17, the root mean square error has been reduced by 3.14 g m−3, and the mean relative error has been reduced by 34.00 %. This research shows that millimeter wave backhaul link provides high-precision data for the measurement of water vapor density and has a positive effect on future weather forecast research. </jats:p