Global wave loads on a damaged ship

A computational tool was applied based on a two dimensional linear method to predict the hydrodynamic loads for damaged ships. Experimental tests on a ship model have also been carried out to predict the hydrodynamic loads in various design conditions. The results of the theoretical method and experimental tests are compared to validate the theoretical method. The extreme wave induced loads have been calculated by short term prediction. For the loads in intact condition, the prediction with duration of 20 years at sea state 5 is used, while for loads in damaged conditions the prediction in 96 hours exposure time at sea 3 is used. The maximum values of the most probable extreme amplitudes of dynamic wave induced loads in damaged conditions are much less than those in intact condition because of the reduced time. An opening could change the distribution of not only stillwater bending moment but also wave-induced bending moment. It is observed that although some cross sections are not structurally damaged, the total loads acting on these cross sections after damage may be increased dramatically compared to the original design load in intact condition

Handcycling: training effects of a specific dose of upper body endurance training in females

Purpose: This study aims to evaluate a handcycling training protocol based on ACSM guidelines in a well-controlled laboratory setting. Training responses of a specific dose of handcycling training were quantified in a homogeneous female subject population to obtain a more in depth understanding of physiological mechanisms underlying adaptations in upper body training. Methods: 22 female able-bodied participants were randomly divided in a training (T) and control group (C). T received 7-weeks of handcycling training, 3 × 30 min/week at 65 % heart rate reserve (HRR). An incremental handcycling test was used to determine local, exercise-specific adaptations. An incremental cycling test was performed to determine non-exercise-specific central/cardiovascular adaptations. Peak oxygen uptake (peakVO2), heart rate (peakHR) and power output (peakPO) were compared between T and C before and after training. Results: T completed the training sessions at 65 ± 3 % HRR, at increasing power output (59.4 ± 8.2 to 69.5 ± 8.9 W) over the training program. T improved on handcycling peakVO2 (+18.1 %), peakPO (+31.9 %), and peakHR (+4.0 %). No improvements were found in cycling parameters. Conclusion: Handcycling training led to local, exercise-specific improvements in upper body parameters. Results could provide input for the design of effective evidence-based training programs specifically aimed at upper body endurance exercise in females

Sustainable polymer foaming using high pressure carbon dioxide: A review on fundamentals, processes and applications

In recent years, carbon dioxide (CO2) has proven to be an environmentally friendly foaming agent for the production of polymeric foams. Until now, extrusion is used to scale-up the CO2-based foaming process. Once the production of large foamed blocks is also possible using the CO2-based foaming process, it has the potential to completely replace the currently used foam production process, thus making the world-wide foam production more sustainable. This review focuses on the polymer–CO2-foaming process, by first addressing the principles of the process, followed by an overview of papers on nucleation and cell growth of CO2 in polymers. The last part will focus on application of the process for various purposes, including bulk polymer foaming, the production of bioscaffolds and polymer blends

Ultrasound-induced polymerization of methyl methacrylate in liquid carbon dioxide : a clean and safe route to produce polymers with controlled molecular weight

Ultrasound-induced cavitation is known to enhance chemical reactions as well as mass transfer at ambient pressures. Ultrasound is rarely studied at higher pressures, since a high static pressure hampers the growth of cavities. Recently, we have shown that pressurized carbon dioxide can be used as a medium for ultrasound-induced reactions, because the static pressure is counteracted by the higher vapor pressure, which enables cavitation. With the use of a dynamic bubble model, the possibility of cavitation and the resulting hot-spot formation upon bubble collapse have been predicted. These simulations show that the implosions of cavities in high-pressure fluids generate temperatures at which radicals can be formed. To validate this, radical formation and polymerization experiments have been performed in CO2-expanded methyl methacrylate. The radical formation rate is approximately 1.5*1014 s-1 in this system. Moreover, cavitation-induced polymerizations result in high-molecular weight polymers. This work emphasizes the application potential of sonochemistry for polymerization processes, as cavitation in CO2-expanded monomers has shown to be a clean and safe route to produce polymers with a controlled molecular weight

Foaming of amorphous polymers and blends in supercritical CO2: Solubility versus block copolymers addition

Supercritical CO2 (scCO(2)) is used as a medium for foaming amorphous polymers. A study of the solubility of supercritical CO2 in several amorphous polymers (PS and PMMA) and blends is performed, followed by an investigation of the foaming behavior of the polymer-gas systems. Nano-structuring triblock copolymers (styrene-co-butadiene-co-methylmethacrylate SBM and methylmethacrylate-co-butylacrylate-co-methylmethacrylate MAM) were blended as additives to PS or PMMA by extrusion. The addition of these triblock copolymers results in an important weight gain ratio of gas in a wide range of temperatures (from 25 to 80 degrees C), relating this weight gain ratio to the foaming behavior of the blends (CO2 is preferentially located in the micro or nano-domains issued from the structuration of the block copolymer). Foaming is carried out in a batch one-step scCO(2) process, keeping constant the saturation pressure and depressurization rate (300 bar and 60 bar/min, respectively). Influence of saturation temperature (25-85 degrees C) on the final porous structure is shown. In spite of the influence of the terpolymer on the weight gain ratio, the structuration is believed to provide a good control of microcellular foams in PS and PMMA

Temperature-programmed desorption of n-hexane from hydrated HZSM-5 and NH(4)ZSM-5 zeolites

Temperature-programmed desorption coupled with mass spectrometer as a detector (TPD), IR and C-13 NMR measurements are used to study the adsorption of n-hexane on hydrated HZSM-5 and NH(4)ZSM-5 zeolites. The C-13 NMR measurements show that n-hexane can access the pore structure of ZSM-5 zeolites previously saturated with water. TPD spectra of n-hexane are monitored in the temperature region 50-300 degrees C, in the case of fully or partially hydrated samples; two-stage desorption of n-hexane is found. Simultaneous desorption of water and n-hexane in the same temperature region are found, in all investigated samples