The effects of water depth on the wave-induced vertical bending moment and shearing force on a very large FPSO are studied by experiments and computations for regular and irregular waves. The restricted water depth co...The effects of water depth on the wave-induced vertical bending moment and shearing force on a very large FPSO are studied by experiments and computations for regular and irregular waves. The restricted water depth composite Green function is employed to develop a program for the computation of the hydrodynamic coefficients of the very large FPSO at shallow water. A three-segment model with 1∶100 scale is tested in the State Key Laboratory of Ocean Engineering at Shanghai Jiao Tong University for the verification of the numerical method. The experimental and computational results show that the water depth has a substantial effect on wave-induced loads. The wave-induced vertical loads increase with the decrease of water depth for shallow water. Especially, for ultra-shallow water these loads increase very evidently with the decrease of water depth. The long-term prediction values of wave-induced vertical loads increase with the decrease of the ratio of water depth to draught. The long-term prediction values of wave-induced vertical loads are about 8% larger than those for deep water when the ratio of water depth to draught is 3.0. However, water depth hardly affects the long-term prediction values of wave-induced loads when the ratio of water depth to draught is larger than 5.0.展开更多
A computer code based on the double-body potential flow model and the classic source panel method has been developed to study various problems of hydrodynamic interaction between ships and other objects with solid bou...A computer code based on the double-body potential flow model and the classic source panel method has been developed to study various problems of hydrodynamic interaction between ships and other objects with solid boundaries including the seabed. A peculiarity of the proposed implementation is the application of the so-called ＂moving-patch＂ method for simulating steady boundaries of large extensions. The method is based on an assumption that at any moment just the part of the boundary （＂moving patch＂） which lies close to the interacting ship is significant for the near-field interaction. For a specific case of the fiat bottom, comparative computations were performed to determine optimal dimensions of the patch and of the constituting panels based on the trade-off between acceptable accuracy and reasonable efficiency. The method was applied to estimate the sway force on a ship hull moving obliquely across a dredged channel. The method was validated for a case of ship-to-ship interaction when tank data were available. This study also contains a description of a newly developed spline approximation algorithm necessary for creating consistent discretizations of ship hulls with various degrees of refinement.展开更多
Objective In order to characterize the feature of stress response induced by stressor with both physical and psychological natures, the effect of water restriction performed in different experimental modes on the phys...Objective In order to characterize the feature of stress response induced by stressor with both physical and psychological natures, the effect of water restriction performed in different experimental modes on the physiological parameters, psychological behavioral manifestations and brain c-Fos expressions were observed and compared. Methods 58 male Wistar rats were used and randomly divided into three experimental groups （n=18 for each） and a control group （n=4）. In control group, the rats were allowed to access drinking water freely at all experimental period. In the experimental groups the water supply to the rats was restricted. In timed water supply （TW） group, the water was supplied twice a day, 10 min for each in fixed hours every day. In empty bottle-served （EB） and water-restricted （WR） groups, the water was served only once a day for 10 min, either in the early morning or evening, and in the other time point scheduled for water supply only an empty bottle without water was provided in the EB group and nothing was given in the WR group. The quantities of drank water and eaten food, weight-gaining, and behavior score were observed every day. The serum level of corticosterone was assayed and the rats were sacrificed with fixative perfusion of 3 d, 7 d or 14 d respectively, following water restriction （n=6 for each time point in each group）. The brain c-Fos expressions were examined with immunohistochemistry. Results The slowing down of weight-gaining, rise of serum corticosterone level, occurrence of psychological behavioral manifestations of unpeaceful restlessness such as exploring and attacking, enhance of c-Fos expression in the subfomical organ （SFO）, median preoptic nucleus （MnPO）, area postrema （AP）, hypothalamic paraventricular nucleus （PVN）, supraoptic nucleus （SON）, medial （MeA） and central （CeA） amygdaloid nucleus and ventrolateral septum （LSV） were noticed in both EB and WR groups, except the nucleus of solitary tract （NTS） in which the Fos expression was decreased. The changes of Fos expression in most of nuclei in EB group began at day 3, at least persisted till day 7, and backed down at day 14. While in WR group, similar changes started at day 7 and reached its peak at day 14. In TW group, only the concentration of corticosterone at day 7 was slightly increased and the rest indexes observed were unchanged. Conclusion The results indicate that water restriction induces physical as well as psychological stress responses. And the water restrictions experimentally executed in different modes result in different manifestations of behavioral response and brain immediately early gene expression in discrete brain nuclei/regions.展开更多
Feed restriction is a common practice to reduce post weaning digestive disorders in rabbits and to get carcasses with less fat. Hydric restriction is commonly used to induce feed restriction in growing rabbits. Two hy...Feed restriction is a common practice to reduce post weaning digestive disorders in rabbits and to get carcasses with less fat. Hydric restriction is commonly used to induce feed restriction in growing rabbits. Two hydric restriction times （2 h and 4 h per day, continuously） were used in our trial carried in good sanitary conditions. Thirty six rabbits were divided at weaning （28 days） into three groups： R2 with restricted access to drinking water from 35 days to 80 days age of 2 h per day （from 8 a.m. to 10 a.m.）, R4： access to drinking water 4 h per day （from 8 a.m. to 12 a.m.） and T （control group） with unlimited access to drinking water. Six animals from each group were slaughtered at 80 days of age. Carcass measurements and meat quality were studied. Histological study for kidneys was carried out. Relative weight of gastrointestinal tract increases with the degree of restriction： 16.5, 18.4 and 18.9 for T, R4 and R2, respectively （P 〈 0.05）. Perirenal fat was lower in restricted groups but differences were not statically significant. Scapular fat decreases of 2/3 or 1/3 respectively with limiting access to drinking water of 2 h or 4 h per day. Compared to control group （T）, meat of restricted groups contains more water： 70.3%, 70% and 69.3% respectively for R4, R2 and T （P 〈 0.01）. The same tendency was observed for proteins： 19.2%, 19.3% and 17.7% for groups R2, R4 and T. Fat decreases in meat of restricted animals： 8.4%, 8.2% and 8.1% respectively for T, R4 and R2 （P 〈 0.05）. Water restriction induced decrease of carcass and meat adiposity. There were no differences between pH post mortem and pH ultimate （after 24 h） between the three groups. Hydric restriction does not effect on kidney histology.展开更多
The demand for high-speed boats that operating near to shoreline is increasing nowadays.Understanding the behavior and attitude of high-speed boats when moving in different waterways is very important for boat designe...The demand for high-speed boats that operating near to shoreline is increasing nowadays.Understanding the behavior and attitude of high-speed boats when moving in different waterways is very important for boat designer.This research uses a CFD(Computational Fluid Dynamics)analysis to investigate the shallow water effects on prismatic planing hull.The turbulence fl ow around the hull was described by Reynolds Navier Stokes equations RANSE using the k-ɛturbulence model.The free surface was modelled by the volume of fl uid(VOF)method.The analysis is steady for all the ranges of speeds except those close to the critical speed range Fh=0.84 to 1.27 due to the propagation of the planing hull solitary waves at this range.In this study,the planing hull lift force,total resistance,and wave pattern for the range of subcritical speeds,critical speeds,and supercritical speeds have been calculated using CFD.The numerical results have been compared with experimental results.The dynamic pressure distribution on the planing hull and its wave pattern at critical speed in shallow water were compared with those in deep water.The numerical results give a good agreement with the experimental results whereas total average error equals 7%for numerical lift force,and 8%for numerical total resistance.The worst effect on the planing hull in shallow channels occurs at the critical speed range,where solitary wave formulates.展开更多
Background Left ventricular hypertrophy （LVH） is an independent predictor of morbidity and mortality in chronic hemodialysis （CHD） patients. It remains unclear whether efforts to correct fluid overload in young CH...Background Left ventricular hypertrophy （LVH） is an independent predictor of morbidity and mortality in chronic hemodialysis （CHD） patients. It remains unclear whether efforts to correct fluid overload in young CHD can reverse LVH. This prospective single-center cohort study evaluated left ventricular masses index （LVMI） evolution in fluid overloaded young CHD patients with or without water-sodium control. Methods A total of 106 young patients aged between 22 and 44 years on CHD were enrolled in this prospective, control study. Patients were divided into three groups according to the percentage of interdialytic weight gain （PIDWG （%） = 100% x （predialysis weight - dry weight）/dry weight） at baseline. Thirty-six patients with PIDWG more than 5% received health education to restrict water-sodium intake strictly （Group I）. Other 36 patients with comparable fluid status levels （the PIDWG more than 5%） did not receive health education to restrict water-sodium intake strictly （Group Ⅱ） and those with PIDWG less than 5% （Group Ⅲ, n=34） were sewed as controls. Echocardiographic studies were performed to evaluate LVMI at baseline and then after 1, 3 and 6 months. The total follow-up time was 6 months. Results There was no significant difference in clinical data （such as age, gender, aetiology of renal failure and nutritional state, etc.） among the three groups at baseline. At baseline, the prevalence of LVH in Group I, Ⅱ and Ⅲ was 75.0%, 72.2% and 55.9%, respectively. LVMI was directly correlated with PIDWG （r = 0.779, P 〈0.01）. After 6 months, the PIDWG in Group I decreased in mean by （3.77±1.09）%, and LVMI decreased in mean by （27.59±12.15） g/m2. The prevalence of LVH decreased in mean by 25.0%, and the blood pressure decreased in mean by （14.69±11.50） mmHg/ （7.14±7.51） mmHg. The medication category and total medication frequency of hypotensive drugs significantly decreased in Group I at 6 months. However the urine volume and the levels of serum creatinine and serum albumin in Group I were not significantly different compared to the baseline. The level of LVMI in Group Ⅱ was significantly increased after 6 months compared with the baseline. After 6 months, the level of LVMI in Group Ⅲ were not significantly different compared with the baseline. Conclusions A high prevalence of LVH was present in young CHD patients, and was associated with fluid overload. Reduction fuild overload with water-sodium control can reverse LVH in young CHD patients.展开更多
文摘The effects of water depth on the wave-induced vertical bending moment and shearing force on a very large FPSO are studied by experiments and computations for regular and irregular waves. The restricted water depth composite Green function is employed to develop a program for the computation of the hydrodynamic coefficients of the very large FPSO at shallow water. A three-segment model with 1∶100 scale is tested in the State Key Laboratory of Ocean Engineering at Shanghai Jiao Tong University for the verification of the numerical method. The experimental and computational results show that the water depth has a substantial effect on wave-induced loads. The wave-induced vertical loads increase with the decrease of water depth for shallow water. Especially, for ultra-shallow water these loads increase very evidently with the decrease of water depth. The long-term prediction values of wave-induced vertical loads increase with the decrease of the ratio of water depth to draught. The long-term prediction values of wave-induced vertical loads are about 8% larger than those for deep water when the ratio of water depth to draught is 3.0. However, water depth hardly affects the long-term prediction values of wave-induced loads when the ratio of water depth to draught is larger than 5.0.
基金Supported by the Portuguese Foundation for Science and Technology under Grant No.PTDC/ECM/100686/2008
文摘A computer code based on the double-body potential flow model and the classic source panel method has been developed to study various problems of hydrodynamic interaction between ships and other objects with solid boundaries including the seabed. A peculiarity of the proposed implementation is the application of the so-called ＂moving-patch＂ method for simulating steady boundaries of large extensions. The method is based on an assumption that at any moment just the part of the boundary （＂moving patch＂） which lies close to the interacting ship is significant for the near-field interaction. For a specific case of the fiat bottom, comparative computations were performed to determine optimal dimensions of the patch and of the constituting panels based on the trade-off between acceptable accuracy and reasonable efficiency. The method was applied to estimate the sway force on a ship hull moving obliquely across a dredged channel. The method was validated for a case of ship-to-ship interaction when tank data were available. This study also contains a description of a newly developed spline approximation algorithm necessary for creating consistent discretizations of ship hulls with various degrees of refinement.
文摘Objective In order to characterize the feature of stress response induced by stressor with both physical and psychological natures, the effect of water restriction performed in different experimental modes on the physiological parameters, psychological behavioral manifestations and brain c-Fos expressions were observed and compared. Methods 58 male Wistar rats were used and randomly divided into three experimental groups （n=18 for each） and a control group （n=4）. In control group, the rats were allowed to access drinking water freely at all experimental period. In the experimental groups the water supply to the rats was restricted. In timed water supply （TW） group, the water was supplied twice a day, 10 min for each in fixed hours every day. In empty bottle-served （EB） and water-restricted （WR） groups, the water was served only once a day for 10 min, either in the early morning or evening, and in the other time point scheduled for water supply only an empty bottle without water was provided in the EB group and nothing was given in the WR group. The quantities of drank water and eaten food, weight-gaining, and behavior score were observed every day. The serum level of corticosterone was assayed and the rats were sacrificed with fixative perfusion of 3 d, 7 d or 14 d respectively, following water restriction （n=6 for each time point in each group）. The brain c-Fos expressions were examined with immunohistochemistry. Results The slowing down of weight-gaining, rise of serum corticosterone level, occurrence of psychological behavioral manifestations of unpeaceful restlessness such as exploring and attacking, enhance of c-Fos expression in the subfomical organ （SFO）, median preoptic nucleus （MnPO）, area postrema （AP）, hypothalamic paraventricular nucleus （PVN）, supraoptic nucleus （SON）, medial （MeA） and central （CeA） amygdaloid nucleus and ventrolateral septum （LSV） were noticed in both EB and WR groups, except the nucleus of solitary tract （NTS） in which the Fos expression was decreased. The changes of Fos expression in most of nuclei in EB group began at day 3, at least persisted till day 7, and backed down at day 14. While in WR group, similar changes started at day 7 and reached its peak at day 14. In TW group, only the concentration of corticosterone at day 7 was slightly increased and the rest indexes observed were unchanged. Conclusion The results indicate that water restriction induces physical as well as psychological stress responses. And the water restrictions experimentally executed in different modes result in different manifestations of behavioral response and brain immediately early gene expression in discrete brain nuclei/regions.
文摘Feed restriction is a common practice to reduce post weaning digestive disorders in rabbits and to get carcasses with less fat. Hydric restriction is commonly used to induce feed restriction in growing rabbits. Two hydric restriction times （2 h and 4 h per day, continuously） were used in our trial carried in good sanitary conditions. Thirty six rabbits were divided at weaning （28 days） into three groups： R2 with restricted access to drinking water from 35 days to 80 days age of 2 h per day （from 8 a.m. to 10 a.m.）, R4： access to drinking water 4 h per day （from 8 a.m. to 12 a.m.） and T （control group） with unlimited access to drinking water. Six animals from each group were slaughtered at 80 days of age. Carcass measurements and meat quality were studied. Histological study for kidneys was carried out. Relative weight of gastrointestinal tract increases with the degree of restriction： 16.5, 18.4 and 18.9 for T, R4 and R2, respectively （P 〈 0.05）. Perirenal fat was lower in restricted groups but differences were not statically significant. Scapular fat decreases of 2/3 or 1/3 respectively with limiting access to drinking water of 2 h or 4 h per day. Compared to control group （T）, meat of restricted groups contains more water： 70.3%, 70% and 69.3% respectively for R4, R2 and T （P 〈 0.01）. The same tendency was observed for proteins： 19.2%, 19.3% and 17.7% for groups R2, R4 and T. Fat decreases in meat of restricted animals： 8.4%, 8.2% and 8.1% respectively for T, R4 and R2 （P 〈 0.05）. Water restriction induced decrease of carcass and meat adiposity. There were no differences between pH post mortem and pH ultimate （after 24 h） between the three groups. Hydric restriction does not effect on kidney histology.
文摘The demand for high-speed boats that operating near to shoreline is increasing nowadays.Understanding the behavior and attitude of high-speed boats when moving in different waterways is very important for boat designer.This research uses a CFD(Computational Fluid Dynamics)analysis to investigate the shallow water effects on prismatic planing hull.The turbulence fl ow around the hull was described by Reynolds Navier Stokes equations RANSE using the k-ɛturbulence model.The free surface was modelled by the volume of fl uid(VOF)method.The analysis is steady for all the ranges of speeds except those close to the critical speed range Fh=0.84 to 1.27 due to the propagation of the planing hull solitary waves at this range.In this study,the planing hull lift force,total resistance,and wave pattern for the range of subcritical speeds,critical speeds,and supercritical speeds have been calculated using CFD.The numerical results have been compared with experimental results.The dynamic pressure distribution on the planing hull and its wave pattern at critical speed in shallow water were compared with those in deep water.The numerical results give a good agreement with the experimental results whereas total average error equals 7%for numerical lift force,and 8%for numerical total resistance.The worst effect on the planing hull in shallow channels occurs at the critical speed range,where solitary wave formulates.
文摘Background Left ventricular hypertrophy （LVH） is an independent predictor of morbidity and mortality in chronic hemodialysis （CHD） patients. It remains unclear whether efforts to correct fluid overload in young CHD can reverse LVH. This prospective single-center cohort study evaluated left ventricular masses index （LVMI） evolution in fluid overloaded young CHD patients with or without water-sodium control. Methods A total of 106 young patients aged between 22 and 44 years on CHD were enrolled in this prospective, control study. Patients were divided into three groups according to the percentage of interdialytic weight gain （PIDWG （%） = 100% x （predialysis weight - dry weight）/dry weight） at baseline. Thirty-six patients with PIDWG more than 5% received health education to restrict water-sodium intake strictly （Group I）. Other 36 patients with comparable fluid status levels （the PIDWG more than 5%） did not receive health education to restrict water-sodium intake strictly （Group Ⅱ） and those with PIDWG less than 5% （Group Ⅲ, n=34） were sewed as controls. Echocardiographic studies were performed to evaluate LVMI at baseline and then after 1, 3 and 6 months. The total follow-up time was 6 months. Results There was no significant difference in clinical data （such as age, gender, aetiology of renal failure and nutritional state, etc.） among the three groups at baseline. At baseline, the prevalence of LVH in Group I, Ⅱ and Ⅲ was 75.0%, 72.2% and 55.9%, respectively. LVMI was directly correlated with PIDWG （r = 0.779, P 〈0.01）. After 6 months, the PIDWG in Group I decreased in mean by （3.77±1.09）%, and LVMI decreased in mean by （27.59±12.15） g/m2. The prevalence of LVH decreased in mean by 25.0%, and the blood pressure decreased in mean by （14.69±11.50） mmHg/ （7.14±7.51） mmHg. The medication category and total medication frequency of hypotensive drugs significantly decreased in Group I at 6 months. However the urine volume and the levels of serum creatinine and serum albumin in Group I were not significantly different compared to the baseline. The level of LVMI in Group Ⅱ was significantly increased after 6 months compared with the baseline. After 6 months, the level of LVMI in Group Ⅲ were not significantly different compared with the baseline. Conclusions A high prevalence of LVH was present in young CHD patients, and was associated with fluid overload. Reduction fuild overload with water-sodium control can reverse LVH in young CHD patients.
