Air lubrication by means of a bottom cavity is a promising method for ship drag reduction. The characteristics of the bottom cavity are sensitive to the flow field around the ship hull and the effect of drag reduction...Air lubrication by means of a bottom cavity is a promising method for ship drag reduction. The characteristics of the bottom cavity are sensitive to the flow field around the ship hull and the effect of drag reduction, especially the depth of the bottom cavity. In this study, a ship model experiment of a bulk carrier is conducted in a towing tank using the method of air layer drag reduction (ALDR) with different bottom cavity depths. The shape of the air layer is observed, and the changes in resistance are measured. The model experiments produce results of approximately 20% for the total drag reduction at the ship design speed for a 25-mm cavity continuously supplied with air at Cq = 0.224 in calm water, and the air layer covers the whole cavity when the air flow rate is suitable. In a regular head wave, the air layer is easily broken and reduces the drag reduction rate in short waves, particularly when λ/Lw1 is close to one;however, it still has a good drag reduction effect in the long waves.展开更多
Background: Major β-thalassemia occurs when impaired genes received by a neonate from the parents. In most of the parents, there are no apparent clinical manifestation and they just show some impairments in hematolog...Background: Major β-thalassemia occurs when impaired genes received by a neonate from the parents. In most of the parents, there are no apparent clinical manifestation and they just show some impairments in hematological indices. This study was designed to determine prevalence of minor and silent carries parents that have children suffering from major β-thalassemia, compare it with national protocol about prevention of thalassemia. Methods: A blood sample was taken from parents of all major thalassemic patients covered by TaleghaniHospitalin Gorgan (n = 195), CBC and Hemoglobin electrophoresis were done. Data were analyzed using SPSS software. Results: Amongst 196 parents one case have normal level of MCV, MCH, RBC, HbA, HbF and mentzer = 22.05 (0.51%) that diagnosed as alpha triplication/N by real time PCR, RFLP informative. The means of hematological indices were based on the national protocol. Conclusion: Present results showed that there are a few cases of thalassemia disorders with normal MCV, MCH, RBC, Mentzer index and Hb electrophoresis which could be missed in routine and pre-marital screening tests, resulted in a thalassemia child that it is possible in every screening test. Generally, indices were according to range of the national guideline.展开更多
基金supported by the Ministry of Industry and High Technology Marine Scientific Research Projects(Grant No.2011530)the High Performance Marine Technology Key Laboratory of the Ministry of Education Open Foundation(Grant No.2013033102)
文摘Air lubrication by means of a bottom cavity is a promising method for ship drag reduction. The characteristics of the bottom cavity are sensitive to the flow field around the ship hull and the effect of drag reduction, especially the depth of the bottom cavity. In this study, a ship model experiment of a bulk carrier is conducted in a towing tank using the method of air layer drag reduction (ALDR) with different bottom cavity depths. The shape of the air layer is observed, and the changes in resistance are measured. The model experiments produce results of approximately 20% for the total drag reduction at the ship design speed for a 25-mm cavity continuously supplied with air at Cq = 0.224 in calm water, and the air layer covers the whole cavity when the air flow rate is suitable. In a regular head wave, the air layer is easily broken and reduces the drag reduction rate in short waves, particularly when λ/Lw1 is close to one;however, it still has a good drag reduction effect in the long waves.
文摘Background: Major β-thalassemia occurs when impaired genes received by a neonate from the parents. In most of the parents, there are no apparent clinical manifestation and they just show some impairments in hematological indices. This study was designed to determine prevalence of minor and silent carries parents that have children suffering from major β-thalassemia, compare it with national protocol about prevention of thalassemia. Methods: A blood sample was taken from parents of all major thalassemic patients covered by TaleghaniHospitalin Gorgan (n = 195), CBC and Hemoglobin electrophoresis were done. Data were analyzed using SPSS software. Results: Amongst 196 parents one case have normal level of MCV, MCH, RBC, HbA, HbF and mentzer = 22.05 (0.51%) that diagnosed as alpha triplication/N by real time PCR, RFLP informative. The means of hematological indices were based on the national protocol. Conclusion: Present results showed that there are a few cases of thalassemia disorders with normal MCV, MCH, RBC, Mentzer index and Hb electrophoresis which could be missed in routine and pre-marital screening tests, resulted in a thalassemia child that it is possible in every screening test. Generally, indices were according to range of the national guideline.
