MODEL TEST AND COUPLED DYNAMIC ANALYSIS OF A DEEPWATER FPSO WITH INTERNAL TURRET MOORING SYSTEM

Model test is an effective way to verify numerical dynamic analysis of floating system. The diffraction and radiation analysis is carried out in frequency domain based on potential theory to predict motion response of rigid platform. The quasi static and dynamic methods are usually adopted to simulate mooring system, which determines if the whole system is coupled within the analysis. Here model tests are performed to indicate the accuracy of potential theory and quasi static and dynamic methods for the whole system. A FPSO is tested under regular waves to find its RAO. The FPSO with internal turret mooring system under irregular wave, wind and current are also studied in the deepwater basin of Harbin Engineering University. The results are compared between the model test and numerical models, which show the model test results agree well with the coupled numerical model, while the maximum mooring tensions are under estimated in quasi static analysis

MODEL TEST AND COUPLED DYNAMIC ANALYSIS OF A DEEPWATER FPSO WITH INTERNAL TURRET MOORING SYSTEM

Model test is an effective way to verify numerical dynamic analysis of floating system. The diffraction and radiation analysis is carried out in frequency domain based on potential theory to predict motion response of rigid platform. The quasi static and dynamic methods are usually adopted to simulate mooring system, which determines if the whole system is coupled within the analysis. Here model tests are performed to indicate the accuracy of potential theory and quasi static and dynamic methods for the whole system. A FPSO is tested under regular waves to find its RAO. The FPSO with internal turret mooring system under irregular wave, wind and current are also studied in the deepwater basin of Harbin Engineering University. The results are compared between the model test and numerical models, which show the model test results agree well with the coupled numerical model, while the maximum mooring tensions are under estimated in quasi static analysis

NUMERICAL MODELLING AND STUDY OF PARAMETRIC ROLLING FOR C11 CONTAINERSHIP IN REGULAR HEAD SEAS USING CONSISTENT STRIP THEORY

In this paper, a numerical model was proposed to simulate the parametric rolling of ships in head seas. The method was developed in time-domain based on strip theory, in which a consistent way of estimating the radiation forces was applied using impulse response function method. To take the coupling effect into account, the heave and pitch motions were solved together with the rolling motion. Also, the Froude-Krylov forces and hydrostatic forces were evaluated on the instantaneously wetted surface of the ship, in order to model the time varied restoring rolling moment in waves. Based on the developed numerical model, the parametrically roll motions of C11 containership was simulated. The influence of roll damping was investigated using two different methods, and the numerical results were compared with model tests. The comparative study shows that results obtained by the proposed method generally agree well with experimental data. Discussions and possible improvements of the current numerical model were also presented in this paper, with regard to the numerical deviation between the numerical and experimental results when the wave steepness was larger than 0.04

Protective effect of Saussurea involucrata polysaccharide against skin dryness induced by ultraviolet radiation

Background: Exposure to ultraviolet B (UVB) radiation can damage the epidermis barrier function and eventually result in skin dryness. At present, little work is being devoted to skin dryness. Searching for active ingredients that can protect the skin against UVB-induced dryness will have scientific significance.Methods:Saussurea involucrata polysaccharide (SIP) has been shown to have significant antioxidant and anti-photodamage effects on the skin following UVB irradiation. To evaluate the effect of SIP on UVB-induced skin dryness ex vivo, SIP-containing hydrogel was applied in a mouse model following exposure to UVB and the levels of histopathological changes, DNA damage, inflammation, keratinocyte differentiation, lipid content were then evaluated. The underlying mechanisms of SIP to protect the cells against UVB induced-dryness were determined in HaCaT cells.Results: SIP was found to lower UVB-induced oxidative stress and DNA damage while increasing keratinocyte differentiation and lipid production. Western blot analysis of UVB-irradiated skin tissue revealed a significant increase in peroxisome proliferator-activated receptor-α (PPAR-α) levels, indicating that the underlying mechanism may be related to PPAR-α signaling pathway activation.Conclusions: By activating the PPAR-α pathway, SIP could alleviate UVB-induced oxidative stress and inhibit the inflammatory response, regulate proliferation and differentiation of keratinocytes, and mitigate lipid synthesis disorder. These findings could provide candidate active ingredients with relatively clear mechanistic actions for the development of skin sunscreen moisturizers

High-Speed Catamaran’s Longitudinal Motion Attenuation with Active Hydrofoils

This paper mainly studies the longitudinal motion prediction method and control technology of high-speed catamaran using the active hydrofoils. To establish the longitudinal motion equations of the ship basing on the 2.5D theory. Using the CFD software to obtain the hydrodynamic data of the hydrofoil. Bring the hydrodynamic expression of hydrofoils into the longitudinal motion equations of the ship. Predicting the longitudinal motion of High-speed catamaran before and after added the hydrofoils. A specific catamaran has been predicted with this approach, the result indicates this approach is workable and this prediction approach provides the theoretical basis for assessing the stabilization ability of appendages and possess the engineering practical value

Numerical Simulations of Linearly Stratified Flow Past Submerged Bodies

In this study, a methodology was presented to predict density stratified flows in the near-field of submerged bodies. The energy equation in temperature form was solved coupled with momentum and mass conservation equations. Linear stratification was achieved by the definition of the density as a function of temperature. At first, verifications were performed for the stratified flows passing a submerged horizontal circular cylinder, showing excellent agreement with available experimental data. The ability of the method to cope with variable density was demonstrated. Different turbulence models were used for different Re numbers and flow states. Based on the numerical methods proposed in this paper, the stratified flow was studied for the real scale benchmark DAPRA Suboff submarine. The approach used the VOF method for tracing the free surface. Turbulence was implemented with a k − ω based Detached Eddy Simulation (DES) approach. The effects of submarine speed, depth and density gradient on the free surface wave pattern were quantitatively analyzed. It was shown that, with the increasing of the speed of the submarine, the wavelength and wave height of the free surface wave were gradually increasing. The wave height of the free surface wave was gradually reduced as the submarine’s depth increased. Relative to the speed and submarine depth, the changes of the gradient density gradient have negligible effects on the free surface wave field

NeSSM: a Next-generation Sequencing Simulator for Metagenomics.

BACKGROUND: Metagenomics can reveal the vast majority of microbes that have been missed by traditional cultivation-based methods. Due to its extremely wide range of application areas, fast metagenome sequencing simulation systems with high fidelity are in great demand to facilitate the development and comparison of metagenomics analysis tools. RESULTS: We present here a customizable metagenome simulation system: NeSSM (Next-generation Sequencing Simulator for Metagenomics). Combining complete genomes currently available, a community composition table, and sequencing parameters, it can simulate metagenome sequencing better than existing systems. Sequencing error models based on the explicit distribution of errors at each base and sequencing coverage bias are incorporated in the simulation. In order to improve the fidelity of simulation, tools are provided by NeSSM to estimate the sequencing error models, sequencing coverage bias and the community composition directly from existing metagenome sequencing data. Currently, NeSSM supports single-end and pair-end sequencing for both 454 and Illumina platforms. In addition, a GPU (graphics processing units) version of NeSSM is also developed to accelerate the simulation. By comparing the simulated sequencing data from NeSSM with experimental metagenome sequencing data, we have demonstrated that NeSSM performs better in many aspects than existing popular metagenome simulators, such as MetaSim, GemSIM and Grinder. The GPU version of NeSSM is more than one-order of magnitude faster than MetaSim. CONCLUSIONS: NeSSM is a fast simulation system for high-throughput metagenome sequencing. It can be helpful to develop tools and evaluate strategies for metagenomics analysis and it's freely available for academic users at http://cbb.sjtu.edu.cn/~ccwei/pub/software/NeSSM.php

The distributions of read lengths.

<p>X axis: the lengths of reads. Each interval is 10 bps. For example, every read with length from 100 bps to 109 bps is counted to the bin of 100 bps; Y axis: the number of reads with lengths in a certain interval. The distributions in NeSSM and GemSIM are close to the actual distribution in Dataset E.</p

The proportions of unique, not unique and not hit reads for 454 simulation datasets from NeSSM.

<p>Unique: the read is mapped back only to its original genome; Not unique: the read is mapped back to more than one reference genomes; Not hit: the read can’t be mapped back to any reference genome. LC-100 is the simulated data from the low complexity metagenome (Dataset A) with read length 100 bps and other datasets are named similarly for simulated data derived from Dataset B and C.</p>*<p>most reads of not hit are because of the repeats in the reads so that they can’t be mapped back uniquely by Blast.</p

The comparison of the proportions of different kinds of substitutions before and after simulation.

<p>The values above the black lines are estimated from Dataset D and the values below are calculated from NeSSM’s simulation. For example, the row of base “A” shows probabilities of substitutions errors from A to other bases.</p