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This article presents research results on building a model to reproduce ship vibrations based on a parallel robot with 6 degrees of freedom on the Gough-Stewart platform. Vibration data at the ship's center of gravity, calculated by simulation software, will be inputted into the model. The regenerative control system uses a simple PID controller to control input trajectory tracking. Simulation results on Matlab/Simulink software have demonstrated the reproduction of ship vibrations within the allowable error. [ABSTRACT FROM AUTHOR]

After a long period of use, some important technical parameters of the main marine diesel engines (MDE) gradually become worse, such as the turbine speed, intake pressure, exhaust temperature, engine power, and specific fuel oil consumption (SFOC). This paper studies the affections of the turbine nozzle cross-sectional area (AT) to MDE and presents a method of AT adjustment to improve the performances of MDE. A mathematical model of an engine was built based on the existent engine construction and the theory of the diesel engine working cycle and the simulation was programmed by Matlab/Simulink. This simulation model accuracy was evaluated through the comparison of simulation results and experimental data of the MDE. The accuracy testing results were acceptable (within 5%). The influences of AT on the engine working parameters and the finding optimization point were conducted by using the simulation program to study. The predicted optimization point of the nozzle was used to improve the engine’s performances on board. The integration of the simulation and experiment studies showed its effectiveness in the practical application of the marine diesel engine field. [ABSTRACT FROM AUTHOR]

Most existing treemaps achieve the space utilization of a single geometrical area, mostly rectangle. Limiting visualization to rectangles could block the human capability on graph recognition, including orientation, shape and differentiation etc. To relax rectangular constraint, we propose a flexible enclosure approach with three algorithms. It partitions large hierarchical structures within a confined display area with different shapes for real-time applications. Our approach is based on the combination of Divide-and-Conquer method and the treemap paradigm. The partitioning algorithms generate three types of layouts with polygonal, angular and rectangular titling, which are flexible to be used separately or combined. We present technical details including the visualization results in the experiments and in the cases studies with real data sets. We evaluated the visualization based on graph drawing aesthetics and optimization criteria. Our usability study shows that (1) treemaps with layout variability support utilization of human capability in graph perception and (2) treemaps adopted in different shaped containers could have a positive impact on user satisfaction and awareness during visual data exploration. [ABSTRACT FROM AUTHOR]

We propose a user-centered visual explorer (UcVE) for progressive comparing multiple visualization units in spatiotemporal space. We create unique unit visualization with the customizable aggregated view based on the visual metaphor of flower bursts. Each visualization unit is encoded with the abstraction of spatiotemporal properties. To reduce user cognition load, UcVE allows users to visualize, save, and track in-the-process exploration results. In coordination of storage sequence and block tracking views, UcVE can facilitate comparison with multiple visualization units concurrently, selected from historical and current exploration results. UcVE offers a flexible geo-based layout, with aggregation functions and temporal views of the timeline with categorized events, to maximize the user's exploration capabilities. Finally, we demonstrate the usefulness by using COVID-19 datasets, case studies with different user scenarios, and expert feedback. [ABSTRACT FROM AUTHOR]

In vitro and in vivo antioxidant activities of the Vietnam-grown Ophiocordyceps sobolifera were investigated for the first time. The contents of phenolic and flavonoid compounds found in O. sobolifera were 18.08 ± 0.52 mg GAE/g dry weight and 10.48 ± 0.02 mg QUE/g dry weight, respectively, and the total antioxidant capacity of the extracts was equivalent to 18.25 ± 0.15 mg GA/g dry weight or 10.24 ± 0.03 mg AS/g dry weight. At concentration 2000 µg/mL, the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity of water extracts from Ophiocordyceps sobolifera was 80 %. The amounts of gallic acid, quercetin, quercitrin, and hesperidin dominated the extracts at 193.60 ± 0.02; 142.07 ± 0.02; 544.53 ± 0.03 and 110.08 ± 0.01 µg/g, respectively, out of a total of 990.27 µg/g dry weight active phenolic fraction. In the in vivo assays, the Ophiocordyceps sobolifera extract showed its ability in protecting kidneys of rats induced injury by cisplatin via decreasing levels of creatinine (47.7 %) and Blood urea nitrogen (BUN) (25.53 %) in blood plasma and malondialdehyde (MDA) (52.41 %) level in renal tissue. The findings of this study provided evidence that Ophiocordyceps sobolifera is a promising resource of natural antioxidants. [Display omitted] • Ophiocordyceps sobolifera extract (OSE) exhibits good antioxidant activity. • OSE has high total phenolics, total flavonoids, and total antioxidant capacity. • OSE attenuates cisplatin-induced kidney injury in rats. • Gallic acid, quercetin, quercitrin, and hesperidin in OSE were determined. [ABSTRACT FROM AUTHOR]

• The induction, growth and maturation of Begonia somatic embryos were changed under MG. • MG influenced SE through altering endogenous hormone biosynthesis and energy metabolism. • Energy metabolism was the key for high frequency SE induction under clinorotation. • An increase in biomass and chlorophyll content in response to MG was observed. • Long-term exposure to MG promoted somatic embryo maturation, induced stomatal morphological distortion. The present study provides a visual insight into the effects of simulated microgravity (MG) on somatic embryogenesis (SE) in Begonia through the analysis of phytohormone fluctuations and energy metabolism. To investigate this relationship, thin cell layer culture model was first used. The results showed that MG changed the phytohormone content and stimulated starch biosynthesis to convert into sugar to release energy needed for regeneration and proliferation. Moreover, from the results it is likely that MG accelerated the initiation and subsequently maturation and aging of SE via decrease of AUX and increase of ABA. High content of GA, CKs, starch, sugar and low ABA as well as high CKs/ABA ratio were responsible for the increase in the number of embryos under clinorotation which was 1.57-fold higher than control after 90 days. The increase in fresh and dry weight of somatic embryos and chlorophyll content under MG were confirmed as their adaptive responses to gravitational stress. However, long-term exposure to MG (120 days) stimulated biosynthesis of ABA levels 1.85-fold higher than controls, which resulted in a decrease in chlorophyll content, increase in number of mature embryos and stomata length. These results revealed that MG regulated the induction, differentiation and senescence of somatic embryos via a biochemical interaction pathway. [ABSTRACT FROM AUTHOR]

Introduction Postnatal depression is a serious mental health problem. In low-income countries, there has been only limited research investigating the direct link between childrearing attitude and maternal mood. The present study sought to determine the prevalence of probable depressive state among mothers in Vietnam, and to examine its risk factors with respect to social support and maternal childrearing attitude. Methods A questionnaire survey was conducted in 299 consecutive mothers who visited Tu Du Obstetrical and Gynecological Hospital, a tertiary hospital, for regular check-up between one and three months postpartum. The questionnaire was administered by trained pediatricians in October through December 2007. Depression was assessed using a two-question case-finding instrument for depression. Results Sixty-eight of the 294 (23.1%) mothers of singletons were assessed as having probable depressive state. Parental and familial conflict and recent moving was strongly associated with probable depressive state. In terms of childrearing attitude, the following factors increased risk of probable depressive state of mothers; lack of confidence (adjusted odds ratio = 2.74, 95% confidence interval: 1.40-5.38), and less relaxed feeing (adjusted odds ratio = 2.85, 95% confidence interval: 1.21-6.71) after controlling for subjective health. Discussion Mothers who felt unconfident and were less relaxed in childrearing were more likely to report a probable depressive state. Social support factors may have played a role in the depression. A brief screening tool for depression is useful to identify mothers in need of additional support in childrearing. [ABSTRACT FROM AUTHOR]