Maintenance is an important technical measure to maintain and restore the performance status of equipment and ensure the safety of the production process in industrial production,and is an indispensable part of predic...Maintenance is an important technical measure to maintain and restore the performance status of equipment and ensure the safety of the production process in industrial production,and is an indispensable part of prediction and health management.However,most of the existing remaining useful life(RUL)prediction methods assume that there is no maintenance or only perfect maintenance during the whole life cycle;thus,the predicted RUL value of the system is obviously lower than its actual operating value.The complex environment of the system further increases the difficulty of maintenance,and its maintenance nodes and maintenance degree are limited by the construction period and working conditions,which increases the difficulty of RUL prediction.An RUL prediction method for a multi-omponent system based on the Wiener process considering maintenance is proposed.The performance degradation model of components is established by a dynamic Bayesian network as the initial model,which solves the uncertainty of insufficient data problems.Based on the experience of experts,the degree of degradation is divided according to Poisson process simulation random failure,and different maintenance strategies are used to estimate a variety of condition maintenance factors.An example of a subsea tree system is given to verify the effectiveness of the proposed method.展开更多
Balsam fir is an important Christmas tree species, especially in eastern Canada. The natural Christmas tree industry faces a challenge in postharvest needle abscission. Though there have been many studies describing t...Balsam fir is an important Christmas tree species, especially in eastern Canada. The natural Christmas tree industry faces a challenge in postharvest needle abscission. Though there have been many studies describing the physiological triggers and consequences in postharvest balsam fir, there have been no studies describing morphological or ultrastructural changes. Therefore, the objective of this study was to examine changes in stomata and chloroplast of postharvest needles. Branches were collected from low and high needle abscission resistance balsam fir genotypes, placed in water, and displayed in typical household conditions for 11 weeks. Needle abscission, chlorophyll fluorescence, and water uptake were monitored throughout. Needles stomata and chloroplasts were examined under a scanning and transmission electron microscope, respectively, each week. All branches had increased abscission, decreased chlorophyll fluorescence, and decreased water uptake over time. Needle surfaces accumulated fungal hyphae, especially in stomata. Chloroplasts demonstrated some dysfunction within two weeks, with notable decreases in chloroplast starch and increases in plastoglobulins. Within several weeks thylakoid membranes had been dismantled as chloroplasts transformed into gerontoplasts. All biophysical and structural changes were more pronounced in low needle abscission resistant genotypes. This research identifies a potential role for needle fungi in postharvest needle abscission and confirms the postharvest senescence of chloroplasts. Though it was previously speculated that chloroplasts must senesce postharvest, this study identifies how quickly this process occurs and that it occurs at different rates in contrasting genotypes.展开更多
Foran insight into what makes China's foreign trade tick,plus the best international food on offer,head to Yiwu where traders have been flocking for centuries.Iyou think Santa Claus comes from the North Pole,you m...Foran insight into what makes China's foreign trade tick,plus the best international food on offer,head to Yiwu where traders have been flocking for centuries.Iyou think Santa Claus comes from the North Pole,you may want to think twice.He also has another home-Yiwu,where more than 60 percent of the world's Christmas decorations are made.If you're a shopaholic,there's no more interesting place to visit than the world's largest small commodity market.展开更多
Whatdoes Carson want todo today?Carson Cabb is getting ready for Christmas.He is wrapping presents.He has one for each of hisfriends.Christmas is Carson'sfavorite holiday.It is a very special day.While he is wrapp...Whatdoes Carson want todo today?Carson Cabb is getting ready for Christmas.He is wrapping presents.He has one for each of hisfriends.Christmas is Carson'sfavorite holiday.It is a very special day.While he is wrapping presents,he is listening to Christmas music.展开更多
Another Christmas season means that the streets and alleys in Europe and the United States have changed into their“Christmas costumes”,and people are busy choosing Christmas decorations and gifts.These dazzling Chri...Another Christmas season means that the streets and alleys in Europe and the United States have changed into their“Christmas costumes”,and people are busy choosing Christmas decorations and gifts.These dazzling Christmas goods are often originally produced in Yiwu,China.展开更多
Merry Christmas!Many people around theworld love this special holiday.Families celebrate it with different traditions.Many families decorate a Christmas tree together.
Charles Dickens was the greatest critical realists in English literary.Almost all of his novels display his deep concern for the society and great sympathy for the low-class people.A Christmas Carol was written in 184...Charles Dickens was the greatest critical realists in English literary.Almost all of his novels display his deep concern for the society and great sympathy for the low-class people.A Christmas Carol was written in 1843 when the society was unrest.The author created the gothic atmosphere himself,and put his characters into that situation and combined the gothic writing methods with the critical realism in order that the gothic elements could express a kind of strong convulsion,which could strength his criti cism for the society.At the same time,the Gothicism also helped to deepen his criticism for the society.展开更多
The tubing hanger is an important component of the subsea Christmas tree, experiencing big temperature difference which will lead to very high thermal stresses. On the basis of API 17D/ISO 13628-4 and ASME VIII-1, and...The tubing hanger is an important component of the subsea Christmas tree, experiencing big temperature difference which will lead to very high thermal stresses. On the basis of API 17D/ISO 13628-4 and ASME VIII-1, and by comprehensively considering the erosion of oil and the gravity load of the tubing, a calculation model is established by regarding design pressure and thermal stress, and the method for designing the tubing hanger of the horizontal Christmas tree under big temperature difference condition is developed from the fourth strength theory. The proposed theory for strength design of the tubing hanger in big temperature difference is verified by numerical results from ABAQUS.展开更多
As the two most important festivals in China and western countries, Spring Festival and Christmas Day each exempli?fies some of the core values and cultural differences in these two cultures wit which this paper is ma...As the two most important festivals in China and western countries, Spring Festival and Christmas Day each exempli?fies some of the core values and cultural differences in these two cultures wit which this paper is mainly concerned. By comparing the external manners such as the family reunion, shopping, exchanging New Year greetings, the paper explore the internal cultur?al differences determining those different external manners such as the collectivism, individualism, filial piety, ancestor worship and religion, etc. Through those comparisons, this paper will succeed to achieve its goal if it exhibits, as the title suggests, a glimpse of cultural differences.展开更多
The thesis will introduce two festivals,Tibetan New Year and American Christmas,and compare their cultural differences.It tends to find different cultural background of these two festivals reflected,to compare how peo...The thesis will introduce two festivals,Tibetan New Year and American Christmas,and compare their cultural differences.It tends to find different cultural background of these two festivals reflected,to compare how people celebrate them,Including decoration,clothing and activity,and to see their development.The thesis will help people know more about the two typical festivals,which can reflect the different cultures of Tibet and America.展开更多
Thanksgiving and Christmas are two major holidays in the United States. Many people use social media to stay connected with their families and friends, including sharing their holiday experiences. This study utilized ...Thanksgiving and Christmas are two major holidays in the United States. Many people use social media to stay connected with their families and friends, including sharing their holiday experiences. This study utilized a stream of millions of tweets on Twitter to explore how people feel about these two holidays through real-time sentiment analysis. With help of Twitter Streaming API, we discovered the patterns of sentiment changes by hour before and after the two holidays in 2011, thus providing a unique peek into the celebration of these holidays that could not be accomplished with traditional methods. Our analysis suggested that in 2011 people had higher sentiment toward Christmas than Thanksgiving on average. The sentiment reached its maximum on the Thanksgiving Day and on The Christmas Eve and Christmas Day, highlighting stronger zeal for Christmas than Thanksgiving, while remained a stable and lower sentiment before and after the holidays. Typically there was a peak of sentiment toward Thanksgiving and Christmas in the morning of each day around 9:00am (EST). On the Thanksgiving Day the number of tweets on shopping increased rapidly and monotonically to its maximum as time approaching the midnight when people thinking of shopping on the Black Friday, but unexpectedly the sentiment toward shopping dropped quickly and monotonically, displaying the exact opposite trend. We also investigated the shopping distraction on the theme of these two holidays. It was found that there were more people talking about thankfulness than shopping during the Thanksgiving season, but more people talking about shopping than Jesus during the Christmas season.展开更多
A subsea wellhead equipped with obsolete vertical Christmas tree needs to be suspended for subsea tree recovery and subsequently to be permanently abandoned. Due to obsolete Christmas tree design combined with tubing ...A subsea wellhead equipped with obsolete vertical Christmas tree needs to be suspended for subsea tree recovery and subsequently to be permanently abandoned. Due to obsolete Christmas tree design combined with tubing inaccessibility issue,conventional subsea intervention method for setting downhole mechanical plug barriers with a semisubmersible rig or a riserless light well intervention vessel is not feasible to suspend the well. Attempt was made to suspend the well from a riserless light well intervention vessel by setting tubing mechanical plugs in 2017,but the mandrel of the tree running tool (TRT) was sheared off accidently while landing the TRT&subsea intervention lubricator (SIL) on the subsea tree. Due to resin’s superior mechanical and rheological properties,resin was evaluated as a well suspension material to create a suspension barrier. Resin plug was deployed successfully from a dive support vessel (DSV) across the perforations to allow the tree removal at cost effective manner. Resin plugging demonstrates a new approach at well P&A area.展开更多
Festival, an occasion when people come to enjoy themselves. Every country has its own traditional festivals, celebrated by all kinds of activities. In China, the most important festival is Spring Festival, while in Am...Festival, an occasion when people come to enjoy themselves. Every country has its own traditional festivals, celebrated by all kinds of activities. In China, the most important festival is Spring Festival, while in America, the most important festival is Christmas. Festi val differences exist between China and America. With time elapsing, festival culture changes gradually and some new cultural phenome non occurs.展开更多
基金financially supported by the National Key Research and Development Program of China(Grant No.2022YFC3004802)the National Natural Science Foundation of China(Grant Nos.52171287,52325107)+3 种基金High Tech Ship Research Project of Ministry of Industry and Information Technology(Grant Nos.2023GXB01-05-004-03,GXBZH2022-293)the Science Foundation for Distinguished Young Scholars of Shandong Province(Grant No.ZR2022JQ25)the Taishan Scholars Project(Grant No.tsqn201909063)the sub project of the major special project of CNOOC Development Technology,“Research on the Integrated Technology of Intrinsic Safety of Offshore Oil Facilities”(Phase I),“Research on Dynamic Quantitative Analysis and Control Technology of Risks in Offshore Production Equipment”(Grant No.HFKJ-2D2X-AQ-2021-03)。
文摘Maintenance is an important technical measure to maintain and restore the performance status of equipment and ensure the safety of the production process in industrial production,and is an indispensable part of prediction and health management.However,most of the existing remaining useful life(RUL)prediction methods assume that there is no maintenance or only perfect maintenance during the whole life cycle;thus,the predicted RUL value of the system is obviously lower than its actual operating value.The complex environment of the system further increases the difficulty of maintenance,and its maintenance nodes and maintenance degree are limited by the construction period and working conditions,which increases the difficulty of RUL prediction.An RUL prediction method for a multi-omponent system based on the Wiener process considering maintenance is proposed.The performance degradation model of components is established by a dynamic Bayesian network as the initial model,which solves the uncertainty of insufficient data problems.Based on the experience of experts,the degree of degradation is divided according to Poisson process simulation random failure,and different maintenance strategies are used to estimate a variety of condition maintenance factors.An example of a subsea tree system is given to verify the effectiveness of the proposed method.
文摘Balsam fir is an important Christmas tree species, especially in eastern Canada. The natural Christmas tree industry faces a challenge in postharvest needle abscission. Though there have been many studies describing the physiological triggers and consequences in postharvest balsam fir, there have been no studies describing morphological or ultrastructural changes. Therefore, the objective of this study was to examine changes in stomata and chloroplast of postharvest needles. Branches were collected from low and high needle abscission resistance balsam fir genotypes, placed in water, and displayed in typical household conditions for 11 weeks. Needle abscission, chlorophyll fluorescence, and water uptake were monitored throughout. Needles stomata and chloroplasts were examined under a scanning and transmission electron microscope, respectively, each week. All branches had increased abscission, decreased chlorophyll fluorescence, and decreased water uptake over time. Needle surfaces accumulated fungal hyphae, especially in stomata. Chloroplasts demonstrated some dysfunction within two weeks, with notable decreases in chloroplast starch and increases in plastoglobulins. Within several weeks thylakoid membranes had been dismantled as chloroplasts transformed into gerontoplasts. All biophysical and structural changes were more pronounced in low needle abscission resistant genotypes. This research identifies a potential role for needle fungi in postharvest needle abscission and confirms the postharvest senescence of chloroplasts. Though it was previously speculated that chloroplasts must senesce postharvest, this study identifies how quickly this process occurs and that it occurs at different rates in contrasting genotypes.
文摘Foran insight into what makes China's foreign trade tick,plus the best international food on offer,head to Yiwu where traders have been flocking for centuries.Iyou think Santa Claus comes from the North Pole,you may want to think twice.He also has another home-Yiwu,where more than 60 percent of the world's Christmas decorations are made.If you're a shopaholic,there's no more interesting place to visit than the world's largest small commodity market.
文摘Whatdoes Carson want todo today?Carson Cabb is getting ready for Christmas.He is wrapping presents.He has one for each of hisfriends.Christmas is Carson'sfavorite holiday.It is a very special day.While he is wrapping presents,he is listening to Christmas music.
文摘Another Christmas season means that the streets and alleys in Europe and the United States have changed into their“Christmas costumes”,and people are busy choosing Christmas decorations and gifts.These dazzling Christmas goods are often originally produced in Yiwu,China.
文摘Merry Christmas!Many people around theworld love this special holiday.Families celebrate it with different traditions.Many families decorate a Christmas tree together.
文摘Charles Dickens was the greatest critical realists in English literary.Almost all of his novels display his deep concern for the society and great sympathy for the low-class people.A Christmas Carol was written in 1843 when the society was unrest.The author created the gothic atmosphere himself,and put his characters into that situation and combined the gothic writing methods with the critical realism in order that the gothic elements could express a kind of strong convulsion,which could strength his criti cism for the society.At the same time,the Gothicism also helped to deepen his criticism for the society.
基金financially supported by the National Science and Technology Major Project of China(Grant No.2011ZX05026-003-02)the National High Technology Research and Development Program of China(863 Program,Grant No.2012AA09A205)
文摘The tubing hanger is an important component of the subsea Christmas tree, experiencing big temperature difference which will lead to very high thermal stresses. On the basis of API 17D/ISO 13628-4 and ASME VIII-1, and by comprehensively considering the erosion of oil and the gravity load of the tubing, a calculation model is established by regarding design pressure and thermal stress, and the method for designing the tubing hanger of the horizontal Christmas tree under big temperature difference condition is developed from the fourth strength theory. The proposed theory for strength design of the tubing hanger in big temperature difference is verified by numerical results from ABAQUS.
文摘As the two most important festivals in China and western countries, Spring Festival and Christmas Day each exempli?fies some of the core values and cultural differences in these two cultures wit which this paper is mainly concerned. By comparing the external manners such as the family reunion, shopping, exchanging New Year greetings, the paper explore the internal cultur?al differences determining those different external manners such as the collectivism, individualism, filial piety, ancestor worship and religion, etc. Through those comparisons, this paper will succeed to achieve its goal if it exhibits, as the title suggests, a glimpse of cultural differences.
文摘The thesis will introduce two festivals,Tibetan New Year and American Christmas,and compare their cultural differences.It tends to find different cultural background of these two festivals reflected,to compare how people celebrate them,Including decoration,clothing and activity,and to see their development.The thesis will help people know more about the two typical festivals,which can reflect the different cultures of Tibet and America.
文摘Thanksgiving and Christmas are two major holidays in the United States. Many people use social media to stay connected with their families and friends, including sharing their holiday experiences. This study utilized a stream of millions of tweets on Twitter to explore how people feel about these two holidays through real-time sentiment analysis. With help of Twitter Streaming API, we discovered the patterns of sentiment changes by hour before and after the two holidays in 2011, thus providing a unique peek into the celebration of these holidays that could not be accomplished with traditional methods. Our analysis suggested that in 2011 people had higher sentiment toward Christmas than Thanksgiving on average. The sentiment reached its maximum on the Thanksgiving Day and on The Christmas Eve and Christmas Day, highlighting stronger zeal for Christmas than Thanksgiving, while remained a stable and lower sentiment before and after the holidays. Typically there was a peak of sentiment toward Thanksgiving and Christmas in the morning of each day around 9:00am (EST). On the Thanksgiving Day the number of tweets on shopping increased rapidly and monotonically to its maximum as time approaching the midnight when people thinking of shopping on the Black Friday, but unexpectedly the sentiment toward shopping dropped quickly and monotonically, displaying the exact opposite trend. We also investigated the shopping distraction on the theme of these two holidays. It was found that there were more people talking about thankfulness than shopping during the Thanksgiving season, but more people talking about shopping than Jesus during the Christmas season.
文摘A subsea wellhead equipped with obsolete vertical Christmas tree needs to be suspended for subsea tree recovery and subsequently to be permanently abandoned. Due to obsolete Christmas tree design combined with tubing inaccessibility issue,conventional subsea intervention method for setting downhole mechanical plug barriers with a semisubmersible rig or a riserless light well intervention vessel is not feasible to suspend the well. Attempt was made to suspend the well from a riserless light well intervention vessel by setting tubing mechanical plugs in 2017,but the mandrel of the tree running tool (TRT) was sheared off accidently while landing the TRT&subsea intervention lubricator (SIL) on the subsea tree. Due to resin’s superior mechanical and rheological properties,resin was evaluated as a well suspension material to create a suspension barrier. Resin plug was deployed successfully from a dive support vessel (DSV) across the perforations to allow the tree removal at cost effective manner. Resin plugging demonstrates a new approach at well P&A area.
文摘Festival, an occasion when people come to enjoy themselves. Every country has its own traditional festivals, celebrated by all kinds of activities. In China, the most important festival is Spring Festival, while in America, the most important festival is Christmas. Festi val differences exist between China and America. With time elapsing, festival culture changes gradually and some new cultural phenome non occurs.
