Evaluation of Damage Indices for Rectangular Concrete-filled Steel Tube Structures

The paper aims to select a simple and effective damage index for estimating the extent of damage of rectangular concrete-filled steel tube (RCFT) structures subjected to ground motions. Two experimental databases of cyclic tests conducted on RCFT columns and frames are compiled. Test results from the database are then used to evaluate six different damage indices, including the ductility ratio (μ), drift ratio, initial-to-secant stiffness ratio (DKJ), modified initial-to-secant stiffness ratio (Dms), energy coefficient (E), and the combined damage index (DPA) as a benchmark indicator. Selection criteria including correlation, efficiency, and proficiency are utilized in the selection process. The optimal alternative for DPA is identified on the basis of a comprehensive evaluation. The evaluations indicate that Dms previously proposed by some of the authors is the most appropriate substitution of DPA, followed by the drift ratio. For the case of the slenderness ratio less than or equal to 30, the same grades of relation between the investigated damage indices and the benchmark are observed. However, in the case of the slenderness ratio larger than 30, the drift ratio tends to be the optimal alternative. In most cases, μ is proved to be an inadequate replacement of DPA

Robust Radiation Sources Localization Based on the Peak Suppressed Particle Filter for Mixed Multi-Modal Environments

This paper addresses a detection problem where sparse measurements are utilized to estimate the source parameters in a mixed multi-modal radiation field. As the limitation of dimensional scalability and the unimodal characteristic, most existing algorithms fail to detect the multi-point sources gathered in narrow regions, especially with no prior knowledge about intensity and source number. The proposed Peak Suppressed Particle Filter (PSPF) method utilizes a hybrid scheme of multi-layer particle filter, mean-shift clustering technique and peak suppression correction to solve the major challenges faced by current existing algorithms. Firstly, the algorithm realizes sequential estimation of multi-point sources in a cross-mixed radiation field by using particle filtering and suppressing intensity peak value, while existing algorithms could just identify single point or spatially separated point sources. Secondly, the number of radioactive sources could be determined in a non-parametric manner as the fact that invalid particle swarms would disperse automatically. In contrast, existing algorithms either require prior information or rely on expensive statistic estimation and comparison. Additionally, to improve the prediction stability and convergent performance, distance correction module and configuration maintenance machine are developed to sustain the multimodal prediction stability. Finally, simulations and physical experiments are carried out in aspects such as different noise level, non-parametric property, processing time and large-scale estimation, to validate the effectiveness and robustness of the PSPF algorithm

Research on the Wear Characteristics of the Hook Teeth of Cotton Pickers

As a key core component of cotton pickers, the spindle is prone to wear of the hook teeth. This research explores the wear characteristics of the spindle hook teeth of cotton pickers under different working areas. The sampled spindles were cut, the element composition and hardness of the spindle hook tooth coating and substrate were determined, the surface morphology of the spindle hook tooth was characterized, and its wear area and coating thickness were extracted. Results show that the main constituent elements of the coating and substrate are Cr and Fe, respectively, the hardness of the coating is about 1020 HV0.1, and the hardness of the substrate is 470~840 HV0.1. During the field operation, scratches appeared on the surface of the coating, the coating thickness layer gradually decreased, and the coating peeled off as the operating area increased. Afterward, scratches and oxidized particles appeared on the surface of the substrate, the wear rate accelerated, and the wear area gradually increased. The wear of the spindle hook teeth started to appear from the front and rear tooth tips up to the tooth edge, the back of the tooth, and the doffering edge, hence forming a long boot-shaped wear area

Rapid Construction and Application of a Vector for Tobacco Ringspot Virus-Induced <i>McPDS</i> Silencing in Bitter Gourd

The aim of this study is to facilitate the construction of virus-induced gene silencing vectors and to provide a reference or positive control for gene silencing in bitter gourd. A recombinant TRSV (tobacco ringspot virus) containing two components, pTRSV1 and pTRSV2, was used in this study. The fragment of the McPDS target was cloned into pTRSV2 via combined enzymic ligation during digestion. The TRSV components were agro-infiltrated into tobacco leaves to grow virus particles, which were then extracted and mechanically inoculated into the bitter gourd plants. The effect of TRSV-McPDS-mediated McPDS gene silencing was evaluated by observing the photo-bleaching phenotype, detecting the TRSV virus, and quantifying the downregulation of MCPDS gene expression and chlorophyll contents. The results showed that all bitter gourd plants infected with the empty TRSV or TRSV-McPDS virus grew and developed normally, with no visible signs of viral disease. However, after seven days of inoculation, only the bitter gourd plants that were inoculated with TRSV-McPDS showed obvious photobleaching in the leaves, stems, and buds. The TRSV-specific fragments were tested out in the systemically infected leaves of bitter gourd. The transcription level of the McPDS gene in the leaves dropped by 84.7%. The chlorophyll content also dropped significantly. These data suggest that the rapidly constructed VIGS vector TRSV-McPDS successfully induced McPDS silencing in bitter gourd. Taken together, the results of this study provide a practical method for vector construction in various VIGS applications, as well as a reference and a positive control for TRSV-induced gene silencing in bitter gourd

Catalytic deoxygenation of carboxyl compounds in the hydrothermal liquefaction crude bio-oil via in-situ hydrogen supply by CuO-CeO2/gamma-Al2O3 catalyst

Hydrothermal liquefaction (HTL) has drawn great attention as a potential method to produce bio-oil from biomass waste. However, bio-crude from HTL shows undesired high-oxygen content and needs further deoxygenation upgrading. Herein, stearic acids as a model carboxylic compounds in HTL bio-crude was employed to investigate catalytic deoxygenation performance. Results showed that (CuO)(10)-CeO2/gamma-Al2O3 had the most superior catalytic deoxygenation performance for the stearic acids. The maximum stearic acid conversion rate (96.36%) and total hydrocarbon yield (88.79%) were obtained at 300 degrees C, 12 h, ratio of stearic acid to water 1 : 4. The main catalytic deoxygenation pathways were proposed: carbon monoxide generation (decarbonylation) - in-situ hydrogen generation (water-gas shift) - short-chain fatty acid generation (hydrogenolysis) - n-alkanes generation (decarboxylation, hydrodeoxygenation and hydrogenation). DFT calculation elucidated that CuO-CeO2 reduced the activation energy from 24.8 kcal mol(-1) (vacuum) to 15.0 kcal mol(-1) (catalytic). Thus, deoxygenation via CuO-CeO2/gamma-Al2O3 would be an effective method for upgrading HTL bio-crude