181 research outputs found

    Failure Mode And Reliability Analysis Of Frame Structure

    Get PDF
    In reliability analysis, the correlation between the primary failure mode of a frame structure and other failure modes is very complicated. At present, there are a number of issues associated with the implementation of reliability analysis, including the complex calculation procedure, the low calculation efficiency, and the difficulty in identifying the primary failure mode, etc. Following the framework of reliability analysis for hybrid systems, the reliability of a two-story frame structure is investigated. The internal force distribution in all structural members is analyzed using the numerical method of Finite Element Method (FEM). The critical structural element is calculated, which can help to evaluate the primary failure mode of the frame structure. Once local failure occurs, the internal force redistributes in the system. The pattern of progressive failure of frame structure is then analyzed. The developed numerical model can provide the real-time performance for the structure, which is further employed to conduct reliability analysis. This study demonstrates that the reliability analysis method for hybrid system can reflect the true performance of the structure more realistically.The present work is partially supported by the National Natural Science Foundation of China (Grant Nos. 51204029, 51474050, 51874076 and U1602232) which are gratefully appreciated

    Assessment of heavy metals pollution in sediment of Citarum River, Indonesia

    Get PDF
    Heavy metals have been reported to accumulate in sediment of Citarum River. The measurement of total heavy metals may not be able to provide information about the exact dimension of pollution, thus the determination of different fractions assumed great importance. This study was performed to determine chemical fractions of heavy metals (Cu, Ni, Cr, Pb and Cd) in sediment collected at 8 locations from Citarum River. The sequential extraction procedure was used to extract heavy metals in water-soluble, acid-soluble, MnO occluded, organically bound, FeO occluded and residual fraction in sediment. Bioavailability and potential ecological risk level of heavy metals were evaluated based on bioavailability factor (BF) and risk assessment code (RAC) method. The results showed that Cu, Ni, Cr were mostly in residual form, indicate those from geological sources. Cu had low bioavailability and no risk in all sediment samples of Citarum River. Ni and Cr each was found to have risk at 2 locations. Pb and Cd were found dominantly in non-residual fraction, suggest those from anthropogenic sources. BF and RAC analysis of Pb and Cd suggest that there is a potential risk to the aquatic environment

    Transient Characteristics and Quantitative Analysis of Electromotive Force for DFIG-based Wind Turbines during Grid Faults

    Get PDF

    Influence of agricultural activity on soil morphological and physicochemical properties on sandy beach ridges along the east coast of Peninsular Malaysia

    Get PDF
    Along the east coast of Peninsular Malaysia, beach ridges are formed with interspersed swales, which are referred to locally as beach ridges interspersed with swales (BRIS). Although BRIS soils are regarded as problematic lowland soils for agriculture because of their very sandy texture and concomitant infertility, agricultural activities in such soils have been recently increasing. This study was conducted to characterize the BRIS soils and to evaluate the influence of agricultural activities on soil characteristics and fertility. Three 1-km transects from the shoreline running inland were established; two transects passed through the experimental farm of Cherating Station of the Malaysian Agriculture Research Development Institute while the other transect passed through an adjacent remnant forest. The soils located close to the shoreline and that further inland were classified as Typic Quartzipsamments and Typic Haplohumods, respectively. The soils had a very high sand content, occasionally exceeding 95%, were acidic and had low cation exchange capacity (CEC) values. While soil organic matter was the determining factor for cation exchange capacity, the regression slope of CEC against soil carbon in the Bhs horizon of the Spodosols was different from that in the other horizons. Because the effective CEC value was much lower than the CEC value, the development of the negative charges on variable-charge surfaces seemed to be largely restricted under acidic conditions. For the Spodosols, the levels of aluminum (Al) and iron (Fe) oxides extracted with acid ammonium oxalate and those oxides with dithionite-citrate-sodium bicarbonate were negligible in the A to E horizons, but they showed sharp peaks in the Bhs horizons. Agricultural activities affected the soil in three ways. First, the A horizon of the farm soil had lower amounts of total carbon (C) and nitrogen (N) compared with the forest, suggesting insufficient input of plant litter to sustain original levels of soil organic matter. Second, although the levels of pH, and exchangeable calcium (Ca) and magnesium (Mg), were higher in the farm soil than the forest, exchangeable potassium (K) was occasionally not detected despite fertilizer application. This finding might be due to the preferential adsorption of divalent cations over monovalent K on the variable negative charges on soil organic matter surfaces as well as limited development of the charge sites in the sandy soil. Finally, the Spodosols under agricultural land use had the highest peak of available phosphorus (P) in the Bhs horizon despite its low level in the overlying A and E horizons. While phosphate is known to be immobile relative to other anions, our finding suggest the downward translocation of mineral P from fertilizer and its retention in the Bhs horizon. Based on the findings, soil organic matter was very important in BRIS soil. Increasing organic matter levels of the soils can improve soil fertility through enhancing cation exchange capacity and the resulting increase in basic cations

    Dietary Supplementation with Sea Buckthorn Berry Puree Alters Plasma Metabolomic Profile and Gut Microbiota Composition in Hypercholesterolemia Population

    Get PDF
    Sea buckthorn berries have been reported to have beneficial effects on plasma lipid profile and cardiovascular health. This study aimed to investigate the impact of intervention with sea buckthorn berry puree on plasma metabolomics profile and gut microbiota in hypercholesterolemic subjects. A total of 56 subjects with hypercholesterolemia consumed 90 g of sea buckthorn berry puree daily for 90 days, and plasma metabolomic profile was studied at 0 (baseline), 45, and 90 days of intervention by using proton nuclear magnetic resonance spectroscopy (H-1 NMR). Gut microbiota composition was analyzed at the baseline and after 90 days of supplementation by using high-throughput sequencing. The plasma metabolic profile was significantly altered after 45 days of intervention as compared to the baseline (day 0). A clear trend of returning to the baseline metabolomic profile was observed in plasma when the intervention extended from 45 days to 90 days. Despite this, the levels of several key plasma metabolites such as glucose, lactate, and creatine were lowered at day 90 compared to the baseline levels, suggesting an improved energy metabolism in those patients. In addition, intervention with sea buckthorn puree enriched butyrate-producing bacteria and other gut microbes linked to lipid metabolisms such as Prevotella and Faecalibacterium while depleting Parasutterella associated with increased risks of cardiovascular disease. These findings indicate that sea buckthorn berries have potential in modulating energy metabolism and the gut microbiota composition in hypercholesterolemic patients

    Soil morphological and chemical properties in homegardens on sandy beach ridges along the east coast of Peninsular Malaysia

    Get PDF
    The morphological and chemical properties of homegardens in the beach ridges with interspersed swales (BRIS) soils were evaluated in order to find a clue for developing sustainable agricultural management. Field survey and soil sampling were conducted at the homegardens and secondary forests in Sungai Ular Village and in the experimental farm of Malaysian Agriculture Research Institute (MARDI), Cherating Station. Chemical fertilizers including ash, charcoal waste and plant litter were applied to the homegardens in both the inland-ward area (HG-I) and in the shoreline area (HG-S). Manure was applied in HG-I and seafood waste from fish processing was buried in the soils in HG-S. High correlation was found between total carbon (T-C) and cation exchange capacity (CEC), indicating soil organic matter was the determinant factor for CEC in the very sandy BRIS soils. The levels of T-C, total nitrogen (T-N), and CEC at 0–10 cm in HG-I in parallel with increasing ages of homegardens. The soils in 0–10 cm and 20–30 cm showed higher levels of T-C and T-N with higher C/N ratios in HG-I than in HG-S and the MARDI farm. The high levels of exchangeable Ca, Mg, and K in HG-I compared with the MARDI farm, suggesting that improved CEC with increasing soil organic matter in HG-I heighten the retention of basic cations supplied as chemical fertilizer, ash, and manure. The level of available P was higher in HG-S than HG-I, attributed by the seafood waste application in the shoreline area. Thus, on the BRIS, the levels of soil organic matter and nutrients can be sustained by the homegarden management although it cannot be regarded as a closed system compared with those in the other tropical regions because chemical fertilizer was used and a certain amounts of nutrients seemed to leach down beyond plant rooting depth

    Effect of Acylated and Nonacylated Anthocyanins on Urine Metabolic Profile during the Development of Type 2 Diabetes in Zucker Diabetic Fatty Rats

    Get PDF
    The effect of nonacylated and acylated anthocyanins on urinary metabolites in diabetic rats was investigated. Nonacylated anthocyanins extract from bilberries (NAAB) or acylated anthocyanins extract from purple potatoes (AAPP) was given to Zucker diabetic fatty (ZDF) rats for 8 weeks at daily doses of 25 and 50 mg/kg body weight. 1H NMR metabolomics was applied to study alterations in urinary metabolites from three time points (weeks 1, 4, and 8). Both types of anthocyanins modulated the metabolites associated with the tricarboxylic acid cycle, gut microbiota metabolism, and renal function at weeks 1 and 4, such as 2-oxoglutarate, fumarate, alanine, trigonelline, and hippurate. In addition, only a high dose of AAPP decreased monosaccharides, formate, lactate, and glucose levels at week 4, suggesting improvement in energy production in mitochondria, glucose homeostasis, and oxidative stress. This study suggested different impacts of AAPP and NAAB on the metabolic profile of urine in diabetes. </p
    corecore