Indonesian offshore and coastal areas are vulnerable to swells from Roaring Forties and cyclone disasters.However,the understanding of the characteristics and propagation mechanisms of local disastrous waves is insuff...Indonesian offshore and coastal areas are vulnerable to swells from Roaring Forties and cyclone disasters.However,the understanding of the characteristics and propagation mechanisms of local disastrous waves is insufficient,posing a threat to the construction,maintenance,and protection of coastal structures.This study establishes a multiple nested wave model based on the third-generation wave model WAVEWATCHⅢ.This model includes sole forcing of Roaring Forties and combined forcing of Roaring Forties and cyclone Ernie to simulate the influence of disastrous waves under the Roaring Forties and tropical cyclones in the Indonesian offshore zone and coasts.The following results are obtained.The Indonesian offshore is prevailed by relatively stable southern to southwestern dominant swells and small wind waves under the impacts of the Roaring Forties without cyclone winds.Long propagating swells originated from the Roaring Forties dominate in nearshore coastal waters with deformed directions and strength because of the shoaling effect.展开更多
THE Cameroonian players went wild with joywhen the referee blew the final whistle, ending the match against their Egyptian opponents with an unexpected 2-1 win. Thus ended the 31st edition of the African Cup of Natio...THE Cameroonian players went wild with joywhen the referee blew the final whistle, ending the match against their Egyptian opponents with an unexpected 2-1 win. Thus ended the 31st edition of the African Cup of Nations （ACN）, which took place in Gabon from January 14 to February 5, 2017.展开更多
采用室内测定并结合林间实地调查的方法,研究了新发现的寄生于蛀干害虫白蜡窄吉丁的外寄生蜂——白蜡吉丁肿腿蜂Sclerodermus pupariae Yang et Yao的生物学特性及其人工繁殖技术。结果表明,白蜡吉丁肿腿蜂外寄生于白蜡窄吉丁的幼虫和...采用室内测定并结合林间实地调查的方法,研究了新发现的寄生于蛀干害虫白蜡窄吉丁的外寄生蜂——白蜡吉丁肿腿蜂Sclerodermus pupariae Yang et Yao的生物学特性及其人工繁殖技术。结果表明,白蜡吉丁肿腿蜂外寄生于白蜡窄吉丁的幼虫和蛹及预蛹,是自然控制该害虫的一种重要寄生蜂,自然寄生率为13.9%左右。该蜂在天津1年发生5代,世代重叠明显,寿命长。白蜡吉丁肿腿蜂的卵、幼虫、茧蛹期和全世代的发育起点温度分别为(16.89±0.79)℃,(17.03±1.42)℃,(16.90±1.68)℃和(15.31±0.47)℃。有效积温分别为(33.82±4.13)日.度、(49.11±7.93)日.度、(128.88±27.87)日.度和(277.00±14.15)日.度。雌性成蜂易于低温保存,对寄主有较强的搜索力和攻击力。繁蜂寄主容易大量获得,是生物防治白蜡窄吉丁的重要理想天敌之一。展开更多
为了改善某SUV汽车加速过程中存在的低速抖动和轰鸣问题,进行了振动与噪声测试和仿真分析,提出了将单质量飞轮改成双质量飞轮、减小离合器弹簧的扭转刚度、增大传动轴的轴径以及在传动轴的末端安装扭转减振器等多种优化方案.通过综合路...为了改善某SUV汽车加速过程中存在的低速抖动和轰鸣问题,进行了振动与噪声测试和仿真分析,提出了将单质量飞轮改成双质量飞轮、减小离合器弹簧的扭转刚度、增大传动轴的轴径以及在传动轴的末端安装扭转减振器等多种优化方案.通过综合路况实车试验,发现了安装的扭转减振器的橡胶存在老化和难以控制阻尼的问题.结果表明:低速抖动和轰鸣问题发生在发动机转速在1 200 r·min^(-1)附近,主要由传动系统的低速扭振引起;提出的优化方案能有效改善传动系统的低速扭振问题,同时能降低驾驶员和乘客耳旁的A级噪声2~3 d B;减小离合器的扭转弹簧刚度和增大传动轴的轴径为最终确定的优化方案.展开更多
基金Supported by the National Natural Science Foundation of China(Grant No.51920105013)。
文摘Indonesian offshore and coastal areas are vulnerable to swells from Roaring Forties and cyclone disasters.However,the understanding of the characteristics and propagation mechanisms of local disastrous waves is insufficient,posing a threat to the construction,maintenance,and protection of coastal structures.This study establishes a multiple nested wave model based on the third-generation wave model WAVEWATCHⅢ.This model includes sole forcing of Roaring Forties and combined forcing of Roaring Forties and cyclone Ernie to simulate the influence of disastrous waves under the Roaring Forties and tropical cyclones in the Indonesian offshore zone and coasts.The following results are obtained.The Indonesian offshore is prevailed by relatively stable southern to southwestern dominant swells and small wind waves under the impacts of the Roaring Forties without cyclone winds.Long propagating swells originated from the Roaring Forties dominate in nearshore coastal waters with deformed directions and strength because of the shoaling effect.
文摘THE Cameroonian players went wild with joywhen the referee blew the final whistle, ending the match against their Egyptian opponents with an unexpected 2-1 win. Thus ended the 31st edition of the African Cup of Nations （ACN）, which took place in Gabon from January 14 to February 5, 2017.
文摘采用室内测定并结合林间实地调查的方法,研究了新发现的寄生于蛀干害虫白蜡窄吉丁的外寄生蜂——白蜡吉丁肿腿蜂Sclerodermus pupariae Yang et Yao的生物学特性及其人工繁殖技术。结果表明,白蜡吉丁肿腿蜂外寄生于白蜡窄吉丁的幼虫和蛹及预蛹,是自然控制该害虫的一种重要寄生蜂,自然寄生率为13.9%左右。该蜂在天津1年发生5代,世代重叠明显,寿命长。白蜡吉丁肿腿蜂的卵、幼虫、茧蛹期和全世代的发育起点温度分别为(16.89±0.79)℃,(17.03±1.42)℃,(16.90±1.68)℃和(15.31±0.47)℃。有效积温分别为(33.82±4.13)日.度、(49.11±7.93)日.度、(128.88±27.87)日.度和(277.00±14.15)日.度。雌性成蜂易于低温保存,对寄主有较强的搜索力和攻击力。繁蜂寄主容易大量获得,是生物防治白蜡窄吉丁的重要理想天敌之一。
文摘为了改善某SUV汽车加速过程中存在的低速抖动和轰鸣问题,进行了振动与噪声测试和仿真分析,提出了将单质量飞轮改成双质量飞轮、减小离合器弹簧的扭转刚度、增大传动轴的轴径以及在传动轴的末端安装扭转减振器等多种优化方案.通过综合路况实车试验,发现了安装的扭转减振器的橡胶存在老化和难以控制阻尼的问题.结果表明:低速抖动和轰鸣问题发生在发动机转速在1 200 r·min^(-1)附近,主要由传动系统的低速扭振引起;提出的优化方案能有效改善传动系统的低速扭振问题,同时能降低驾驶员和乘客耳旁的A级噪声2~3 d B;减小离合器的扭转弹簧刚度和增大传动轴的轴径为最终确定的优化方案.
