Closing a single nozzle or multiple nozzles for a temporary casting operation(fewer strands casting)was common in a tundish due to insufficient molten steel or equipment failure.However,nozzle clogging usually happens...Closing a single nozzle or multiple nozzles for a temporary casting operation(fewer strands casting)was common in a tundish due to insufficient molten steel or equipment failure.However,nozzle clogging usually happens under the situation of fewer strands casting.Hence,a temperature deviation index was introduced to characterize the temperature stratification of molten steel for a large capacity tundish,and a new calculation method of residence time curve was used to describe the different flow types of molten steel at each outlet.Based on hydraulics experiment and numerical simulation,important parameters of present case and modified case were compared.Under the situation of fewer strands casting,the proportion of internal-recycle flow after modification decreased from 30.68%to 24.55%;the standard deviation of the response time reduced from 27.59 to 13.16,and the interquartile range of temperature deviation index changed from 0.89 to 0.27.展开更多
Development strategy for heavy-oil reservoirs is one of the important research interests in China National Offshore Oil Corp. （CNOOC） that plans a highly effective development for heavy oil fields in multilayered fl...Development strategy for heavy-oil reservoirs is one of the important research interests in China National Offshore Oil Corp. （CNOOC） that plans a highly effective development for heavy oil fields in multilayered fluvial reservoirs because of their significant influence on marine oil and even on China＇s petroleum production. The characteristics analysis of multilayered fluvial reservoirs in the heavy oil fields in Bohai Bay indicates that large amounts ofoil were trapped in the channel, point bar and channel bar sands. The reserves distribution of 8 oilfields illustrates that the reserves trapped in the main sands, which is 20%-40% of all of the sand bodies, account for 70%-90% of total reserves of the heavy oil fields. The cumulative production from high productivity wells （50% of the total wells） was 75%-90% of the production of the overall oilfield, while only 3%-10% of the total production was from the low productivity wells （30% of the total wells）. And the high productivity wells were drilled in the sands with high reserves abundance. Based on the above information the development strategy was proposed, which includes reserves production planning, selection of well configuration, productivity design, and development modification at different stages.展开更多
Nonglian Village of Sheyang County,Yancheng City.Jiangsu Province has 454 families(1,460 people)and 356 women of childbearing age.In the past,the village was povcrty-stricken and plagued with unwanted births.Between 1...Nonglian Village of Sheyang County,Yancheng City.Jiangsu Province has 454 families(1,460 people)and 356 women of childbearing age.In the past,the village was povcrty-stricken and plagued with unwanted births.Between 1980 and 1990.more than 100 unplanned children were bom.展开更多
more,less,fewer常用来比较数量的多少。【知识梳理】1.more是形容词many,much'许多的'的比较级,既可以修饰可数名词,也可以修饰不可数名词,表示'更多的……'。例如:There will be more trees in the neighborhood.社...more,less,fewer常用来比较数量的多少。【知识梳理】1.more是形容词many,much'许多的'的比较级,既可以修饰可数名词,也可以修饰不可数名词,表示'更多的……'。例如:There will be more trees in the neighborhood.社区里将会有更多的树木。Is there more water pollution in cities?城市有更多的水污染吗?2.less是形容词little'少的'的比较级,与不可数名词连用,表示'更少的……'。展开更多
A new and novel way to encourage carefully planned parenthood among China's farmers:ofer them economic incentives for having fewer children.To show how this plan is working out on the grassroots level,we bring you...A new and novel way to encourage carefully planned parenthood among China's farmers:ofer them economic incentives for having fewer children.To show how this plan is working out on the grassroots level,we bring you short personal accounts from two young farmwomen.展开更多
Ultraprecision grinding is an important approach to efficiently fabricate large complex optical mirrors, and five-axis grinding method is commonly used for ultraprecision grinding. However, this method can hardly meet...Ultraprecision grinding is an important approach to efficiently fabricate large complex optical mirrors, and five-axis grinding method is commonly used for ultraprecision grinding. However, this method can hardly meet the high stiffness requirement for grinding large mirror, especially with a diameter over 2 m. Meanwhile, the use of fewer-axis grinding solves this problem, as it reduces the number of the grinder's axes to improve the rigidity of the system and minimize deformation for hard and brittle materials. But its characteristic of unfixed grinding point which changes with workpiece surface curvature increases geometric complexity and requires a higher geometric shape accuracy of grinding wheel. This paper parameterizes grinding wheel's geometric shape, reveals the relationship between fewer-axis and five-axis grinding methods from the point of view of the differential geometry, and establishes virtual-axis equivalence principium of feweraxis grinding. A quantitative method to determine grinding wheel's geometric parameters and its shaft inclination angle is proposed based on the requirements of geometric properties of optical mirror, grinder features and grinding process. Moreover, according to the properties of Gauss curvature of curved surface, the wear law of the toric grinding wheel is found and the surface geometric error distribution due to wear is achieved for fewer-axis grinding. The correctness of the principium and method above are verified through simulations.展开更多
More details are emerging about the government’s 370-billion-yuaneconomic stimulus package for 2009 Acouple of recent reports detailing thegovernment’s plan to further stimu-late the country’s economy next yearhave...More details are emerging about the government’s 370-billion-yuaneconomic stimulus package for 2009 Acouple of recent reports detailing thegovernment’s plan to further stimu-late the country’s economy next yearhave caused a pleasant stir amonginvestors and enterprises alike.展开更多
男大当婚,女大当嫁。在当今之中国,这条古训的生命力依然强大。然而,这篇短文却让我们感受到了一种令人难以置信的美国新潮婚姻文化:男大不婚,女大不嫁。 据调查,1996年美国1000名未婚女子中的成婚者从1960年的87.5名跌到了49.7名！换言...男大当婚,女大当嫁。在当今之中国,这条古训的生命力依然强大。然而,这篇短文却让我们感受到了一种令人难以置信的美国新潮婚姻文化:男大不婚,女大不嫁。 据调查,1996年美国1000名未婚女子中的成婚者从1960年的87.5名跌到了49.7名！换言之,今天的美国只有5％的未婚女子结婚成家！ 然而,不婚或不嫁,并不意味当今的美国青年男女都成了“禁欲主义者”。下面的这组数据又让我们眼界一开: 同时,未婚而同居者则从1960年的439,000名上升到1998年的4.2million！ 宁可同居而不结婚,这是一个极为复杂的社会现象。本文没有详作探讨,只是顺便提到了以下3点: The secularization(现世化)of society, extended affluence(富裕),a changein what Americans expect from marriage. 笔者认为,其中的第3点比较实际。 本文的另一个重要信息是:and despite a small drop in the divorce rate,nearly 50 percent of all marriages will end in divorce. 当离婚率达到50％的时候,what Americans expect from marriage就可怜,甚至有点可怕了。“男大不婚,女大不嫁”也就不难理解了。展开更多
我一直是贵刊的热心读者。贵刊在1997年第7期发表了余皑媛选译的“Mom,I Want to Live with My Boyfriend”、作为一个“小女初长成”的母亲,我读了之后,久久不能平静,甚至还掉下了伤心的泪水。女儿在外地读大学,回来 度暑假,我同自己...我一直是贵刊的热心读者。贵刊在1997年第7期发表了余皑媛选译的“Mom,I Want to Live with My Boyfriend”、作为一个“小女初长成”的母亲,我读了之后,久久不能平静,甚至还掉下了伤心的泪水。女儿在外地读大学,回来 度暑假,我同自己的女儿促膝长谈,希望她从该文中记取有益的东西,让生活的风帆永远高高升起。今年第5期的《科技英语学习》又刊登了Rosemary Adang的“关于美国女学生未婚先孕的问题”的文章,我也浮想联翩,觉得中国和美国的国情大异,而中国人的许多传统美德是我们民族的源远流长的精神财富,我们应该永远继承和发扬下去。今日,我在Internet上读到了美国中学生的“性况”,惊讶之余,觉得文章信息丰富可靠。有必要让国人知道此真情。作为贵刊前两篇文章的续篇,我寄上加注的全文。望借贵刊一隅刊登。展开更多
妇女长寿的秘密在于生育少,这个看似寻常的观点在本文却有一番学术探讨。在详细考证和研究了英国贵族的生、死和婚姻情况后,有人提出:the secret of a long life appears to be: have fewer children.不仅少生能长寿,晚育也同样能长寿:...妇女长寿的秘密在于生育少,这个看似寻常的观点在本文却有一番学术探讨。在详细考证和研究了英国贵族的生、死和婚姻情况后,有人提出:the secret of a long life appears to be: have fewer children.不仅少生能长寿,晚育也同样能长寿:…women who had their first child later in life lived longer that those who began reproducing early.当然,这个考证和发现尚有待进一步的发掘,文章末尾的一个观点则可视作一重要补充:For genealogy(系谱)studies we cannot distinguish the effects of genetic similarity(遗传类似)from those of common environment, so it remains to be seen whether the observed patterns are due to nature or nurture(营养品).】展开更多
基金the National Natural Science Foundation of China(Grant No.51774031).
文摘Closing a single nozzle or multiple nozzles for a temporary casting operation(fewer strands casting)was common in a tundish due to insufficient molten steel or equipment failure.However,nozzle clogging usually happens under the situation of fewer strands casting.Hence,a temperature deviation index was introduced to characterize the temperature stratification of molten steel for a large capacity tundish,and a new calculation method of residence time curve was used to describe the different flow types of molten steel at each outlet.Based on hydraulics experiment and numerical simulation,important parameters of present case and modified case were compared.Under the situation of fewer strands casting,the proportion of internal-recycle flow after modification decreased from 30.68%to 24.55%;the standard deviation of the response time reduced from 27.59 to 13.16,and the interquartile range of temperature deviation index changed from 0.89 to 0.27.
文摘Development strategy for heavy-oil reservoirs is one of the important research interests in China National Offshore Oil Corp. （CNOOC） that plans a highly effective development for heavy oil fields in multilayered fluvial reservoirs because of their significant influence on marine oil and even on China＇s petroleum production. The characteristics analysis of multilayered fluvial reservoirs in the heavy oil fields in Bohai Bay indicates that large amounts ofoil were trapped in the channel, point bar and channel bar sands. The reserves distribution of 8 oilfields illustrates that the reserves trapped in the main sands, which is 20%-40% of all of the sand bodies, account for 70%-90% of total reserves of the heavy oil fields. The cumulative production from high productivity wells （50% of the total wells） was 75%-90% of the production of the overall oilfield, while only 3%-10% of the total production was from the low productivity wells （30% of the total wells）. And the high productivity wells were drilled in the sands with high reserves abundance. Based on the above information the development strategy was proposed, which includes reserves production planning, selection of well configuration, productivity design, and development modification at different stages.
文摘Nonglian Village of Sheyang County,Yancheng City.Jiangsu Province has 454 families(1,460 people)and 356 women of childbearing age.In the past,the village was povcrty-stricken and plagued with unwanted births.Between 1980 and 1990.more than 100 unplanned children were bom.
文摘more,less,fewer常用来比较数量的多少。【知识梳理】1.more是形容词many,much'许多的'的比较级,既可以修饰可数名词,也可以修饰不可数名词,表示'更多的……'。例如:There will be more trees in the neighborhood.社区里将会有更多的树木。Is there more water pollution in cities?城市有更多的水污染吗?2.less是形容词little'少的'的比较级,与不可数名词连用,表示'更少的……'。
文摘A new and novel way to encourage carefully planned parenthood among China's farmers:ofer them economic incentives for having fewer children.To show how this plan is working out on the grassroots level,we bring you short personal accounts from two young farmwomen.
基金supported by the National Basic Research Program of China ("973" Program) (Grant No. 2011CB013203)
文摘Ultraprecision grinding is an important approach to efficiently fabricate large complex optical mirrors, and five-axis grinding method is commonly used for ultraprecision grinding. However, this method can hardly meet the high stiffness requirement for grinding large mirror, especially with a diameter over 2 m. Meanwhile, the use of fewer-axis grinding solves this problem, as it reduces the number of the grinder's axes to improve the rigidity of the system and minimize deformation for hard and brittle materials. But its characteristic of unfixed grinding point which changes with workpiece surface curvature increases geometric complexity and requires a higher geometric shape accuracy of grinding wheel. This paper parameterizes grinding wheel's geometric shape, reveals the relationship between fewer-axis and five-axis grinding methods from the point of view of the differential geometry, and establishes virtual-axis equivalence principium of feweraxis grinding. A quantitative method to determine grinding wheel's geometric parameters and its shaft inclination angle is proposed based on the requirements of geometric properties of optical mirror, grinder features and grinding process. Moreover, according to the properties of Gauss curvature of curved surface, the wear law of the toric grinding wheel is found and the surface geometric error distribution due to wear is achieved for fewer-axis grinding. The correctness of the principium and method above are verified through simulations.
文摘More details are emerging about the government’s 370-billion-yuaneconomic stimulus package for 2009 Acouple of recent reports detailing thegovernment’s plan to further stimu-late the country’s economy next yearhave caused a pleasant stir amonginvestors and enterprises alike.
文摘男大当婚,女大当嫁。在当今之中国,这条古训的生命力依然强大。然而,这篇短文却让我们感受到了一种令人难以置信的美国新潮婚姻文化:男大不婚,女大不嫁。 据调查,1996年美国1000名未婚女子中的成婚者从1960年的87.5名跌到了49.7名！换言之,今天的美国只有5％的未婚女子结婚成家！ 然而,不婚或不嫁,并不意味当今的美国青年男女都成了“禁欲主义者”。下面的这组数据又让我们眼界一开: 同时,未婚而同居者则从1960年的439,000名上升到1998年的4.2million！ 宁可同居而不结婚,这是一个极为复杂的社会现象。本文没有详作探讨,只是顺便提到了以下3点: The secularization(现世化)of society, extended affluence(富裕),a changein what Americans expect from marriage. 笔者认为,其中的第3点比较实际。 本文的另一个重要信息是:and despite a small drop in the divorce rate,nearly 50 percent of all marriages will end in divorce. 当离婚率达到50％的时候,what Americans expect from marriage就可怜,甚至有点可怕了。“男大不婚,女大不嫁”也就不难理解了。
文摘我一直是贵刊的热心读者。贵刊在1997年第7期发表了余皑媛选译的“Mom,I Want to Live with My Boyfriend”、作为一个“小女初长成”的母亲,我读了之后,久久不能平静,甚至还掉下了伤心的泪水。女儿在外地读大学,回来 度暑假,我同自己的女儿促膝长谈,希望她从该文中记取有益的东西,让生活的风帆永远高高升起。今年第5期的《科技英语学习》又刊登了Rosemary Adang的“关于美国女学生未婚先孕的问题”的文章,我也浮想联翩,觉得中国和美国的国情大异,而中国人的许多传统美德是我们民族的源远流长的精神财富,我们应该永远继承和发扬下去。今日,我在Internet上读到了美国中学生的“性况”,惊讶之余,觉得文章信息丰富可靠。有必要让国人知道此真情。作为贵刊前两篇文章的续篇,我寄上加注的全文。望借贵刊一隅刊登。
文摘妇女长寿的秘密在于生育少,这个看似寻常的观点在本文却有一番学术探讨。在详细考证和研究了英国贵族的生、死和婚姻情况后,有人提出:the secret of a long life appears to be: have fewer children.不仅少生能长寿,晚育也同样能长寿:…women who had their first child later in life lived longer that those who began reproducing early.当然,这个考证和发现尚有待进一步的发掘,文章末尾的一个观点则可视作一重要补充:For genealogy(系谱)studies we cannot distinguish the effects of genetic similarity(遗传类似)from those of common environment, so it remains to be seen whether the observed patterns are due to nature or nurture(营养品).】
