The electrochemical migration（ECM） behavior and mechanism of immersion silver processing circuit board（PCB-ImAg）and hot air solder leveling circuit board（PCB-HASL） under the 0.1 mol/L Na2SO4 absorbed thin liquid...The electrochemical migration（ECM） behavior and mechanism of immersion silver processing circuit board（PCB-ImAg）and hot air solder leveling circuit board（PCB-HASL） under the 0.1 mol/L Na2SO4 absorbed thin liquid films with different thicknesses were investigated using stereo microscopy and scanning electron microscopy（SEM）.Meanwhile,the corrosion tendency and kinetics rule of metal plates after bias application were analyzed with the aid of electrochemical impedance spectroscopy（EIS）and scanning Kelvin probe（SKP）.Results showed that under different humidity conditions,the amount of migrating corrosion products of silver for PCB-ImAg was limited,while on PCB-HASL both copper dendrites and precipitates such as sulfate and metal oxides of copper/tin were found under a high humidity condition（exceeding 85%）.SKP results indicated that the cathode plate of two kinds of PCB materials had a higher corrosion tendency after bias application.An ECM model involving multi-metal reactions was proposed and the differences of ECM behaviors for two kinds of PCB materials were compared.展开更多
OBJECTIVE To provide evidence for breast cancer prevention and control through epidemiological analysis of the incidence, mortality and survival rate of female breast cancer patients in Beijing. METHODS The female reg...OBJECTIVE To provide evidence for breast cancer prevention and control through epidemiological analysis of the incidence, mortality and survival rate of female breast cancer patients in Beijing. METHODS The female registration data in the Beijing urban area from 1982 to 2001 were retrospectively reviewed. The incidence, mortality and survival rate of female breast cancer patients were analyzed using routine and life-table statistical methods. RESULTS During the period of 1982 to 2001, there was a trend of an average annual increase of female breast cancer incidence of 4.6% in urban Beijing, and of 4,9% in the world-population standardized incidence. The epidemiological features of urban Beijing female breast cancer showed：（1）The incidence distribution of different age groups from 25 to 80 years elevated with two peaks at ages of 45- and 70- years; （2）There was an elevation in each age group over the last 20 years; （3）The incidence rate at ages of 35 to 64 reached 95.3/10^5, causing breast cancer to become the number one cancer in females. The changes in the survival rate showed the following： the 5-year observed survival rate （OSR） increased from 62.0% in 1982～1983 to 68.7% in 1987-1988, and the relative-survival rate （RSR） increased from 6613% to 74.2%. The 10-year OSR and RSR in 1987～1988 were 60.3% and 65.1%, and at 15 years 57.5% and 61.3%, respectively. The mortality rate of breast cancer patients fluctuated from 8 to 10 per 105 population over the 20 years of study. CONCLUSION There is a trend of an annual increase in female breast cancer in Beijing. The 5-year survival is being improved gradually while the mortality remains stable. The results demonstrate that the principles of ＂early prevention, diagnosis and treatment＂ for breast cancer are effective in Beijing.展开更多
In this paper, we conduct research on the college English teaching emphasis from the cultural migration and transformation ofthinking perspectives. College English has long been in for the college English subject stat...In this paper, we conduct research on the college English teaching emphasis from the cultural migration and transformation ofthinking perspectives. College English has long been in for the college English subject status. However, college English as a multidisciplinary,interdisciplinary research in the field of discipline construction, it seems, are still stay in the linguistics, language knowledge in academiccharacteristics for its stage of development. Reform of basic college English teaching, the teacher is still teaching main body, is the teaching oflanguage knowledge, since teachers play an important role in language teaching, the teacher wants to penetrate cultural knowledge in teachingand we must strengthen their own culture. Under this basis, this paper proposes the novel ideals on the related issues that will be meaningful andinnovative.展开更多
Doped micro-crystalline silicon films are deposited at temperatures as low as 400 ℃ by the catalytic chemical vapor deposition method using a silane and hydrogen gas mixture. Electrical properties such as the carrier...Doped micro-crystalline silicon films are deposited at temperatures as low as 400 ℃ by the catalytic chemical vapor deposition method using a silane and hydrogen gas mixture. Electrical properties such as the carrier concentration and the Hall mobility are investigated for various measuring temperatures. It is found that the grains of micro-crystalline silicon are preferentially oriented along the (220) direction , and that the Hall mobility is larger than 8 cm 2·V -1 ·s -1 , the carrier concentration is about 1×10 17 cm -1 ～1×10 19 cm -3 at room temperature.展开更多
. A dialect refers to a local variation of a language which is distinguished fi＇om variants of the same language in grammar, lexis, or pronuneiation. A dialect plays an important role in second language learning. It .... A dialect refers to a local variation of a language which is distinguished fi＇om variants of the same language in grammar, lexis, or pronuneiation. A dialect plays an important role in second language learning. It can be a positive element as well as negative one in second language learning. Pingdu dialect as a kind of mandarin variation has its own structure and pronunciation rules. By contrastive analysis, we study the negative transfer of Pingdu Dialect on English pronunciation. We mainly concentrate on how two initials ＂s＂ and ＂z＂ in pinyin which sound like two English consonants/0 /and/6/influence the pronunciation of English consonants/s/and/z/. We also fred the countermeasures to overcome negative transfer of dialect on the acquisition of English pronunciation, thereby helping EFL learners in certain area of China acquire accurate English pronuneiations and enhance the ability of intercultural eommunication.展开更多
The negative pragmatic transfer in second language acquisition has been seen as the major cause of pragmatic failure. In fact, the constant experiencing of negative pragmatic transfer is an active process of learning....The negative pragmatic transfer in second language acquisition has been seen as the major cause of pragmatic failure. In fact, the constant experiencing of negative pragmatic transfer is an active process of learning. The paper investigates the characteristics and classification of the negative pragmatic transfer so that people will have an objective attitude towards it. The author also provides suggestions and strategies so as to help the foreign language learners to establish the confidence in the foreign language study and intercultural communication.展开更多
Defect detection is vital in the nonwoven material industry,ensuring surface quality before producing finished products.Recently,deep learning and computer vision advancements have revolutionized defect detection,maki...Defect detection is vital in the nonwoven material industry,ensuring surface quality before producing finished products.Recently,deep learning and computer vision advancements have revolutionized defect detection,making it a widely adopted approach in various industrial fields.This paper mainly studied the defect detection method for nonwoven materials based on the improved Nano Det-Plus model.Using the constructed samples of defects in nonwoven materials as the research objects,transfer learning experiments were conducted based on the Nano DetPlus object detection framework.Within this framework,the Backbone,path aggregation feature pyramid network(PAFPN)and Head network models were compared and trained through a process of freezing,with the ultimate aim of bolstering the model's feature extraction abilities and elevating detection accuracy.The half-precision quantization method was used to optimize the model after transfer learning experiments,reducing model weights and computational complexity to improve the detection speed.Performance comparisons were conducted between the improved model and the original Nano Det-Plus model,YOLO,SSD and other common industrial defect detection algorithms,validating that the improved methods based on transfer learning and semi-precision quantization enabled the model to meet the practical requirements of industrial production.展开更多
基金Project(51271032)supported by the National Natural Science Foundation of China
文摘The electrochemical migration（ECM） behavior and mechanism of immersion silver processing circuit board（PCB-ImAg）and hot air solder leveling circuit board（PCB-HASL） under the 0.1 mol/L Na2SO4 absorbed thin liquid films with different thicknesses were investigated using stereo microscopy and scanning electron microscopy（SEM）.Meanwhile,the corrosion tendency and kinetics rule of metal plates after bias application were analyzed with the aid of electrochemical impedance spectroscopy（EIS）and scanning Kelvin probe（SKP）.Results showed that under different humidity conditions,the amount of migrating corrosion products of silver for PCB-ImAg was limited,while on PCB-HASL both copper dendrites and precipitates such as sulfate and metal oxides of copper/tin were found under a high humidity condition（exceeding 85%）.SKP results indicated that the cathode plate of two kinds of PCB materials had a higher corrosion tendency after bias application.An ECM model involving multi-metal reactions was proposed and the differences of ECM behaviors for two kinds of PCB materials were compared.
文摘OBJECTIVE To provide evidence for breast cancer prevention and control through epidemiological analysis of the incidence, mortality and survival rate of female breast cancer patients in Beijing. METHODS The female registration data in the Beijing urban area from 1982 to 2001 were retrospectively reviewed. The incidence, mortality and survival rate of female breast cancer patients were analyzed using routine and life-table statistical methods. RESULTS During the period of 1982 to 2001, there was a trend of an average annual increase of female breast cancer incidence of 4.6% in urban Beijing, and of 4,9% in the world-population standardized incidence. The epidemiological features of urban Beijing female breast cancer showed：（1）The incidence distribution of different age groups from 25 to 80 years elevated with two peaks at ages of 45- and 70- years; （2）There was an elevation in each age group over the last 20 years; （3）The incidence rate at ages of 35 to 64 reached 95.3/10^5, causing breast cancer to become the number one cancer in females. The changes in the survival rate showed the following： the 5-year observed survival rate （OSR） increased from 62.0% in 1982～1983 to 68.7% in 1987-1988, and the relative-survival rate （RSR） increased from 6613% to 74.2%. The 10-year OSR and RSR in 1987～1988 were 60.3% and 65.1%, and at 15 years 57.5% and 61.3%, respectively. The mortality rate of breast cancer patients fluctuated from 8 to 10 per 105 population over the 20 years of study. CONCLUSION There is a trend of an annual increase in female breast cancer in Beijing. The 5-year survival is being improved gradually while the mortality remains stable. The results demonstrate that the principles of ＂early prevention, diagnosis and treatment＂ for breast cancer are effective in Beijing.
文摘In this paper, we conduct research on the college English teaching emphasis from the cultural migration and transformation ofthinking perspectives. College English has long been in for the college English subject status. However, college English as a multidisciplinary,interdisciplinary research in the field of discipline construction, it seems, are still stay in the linguistics, language knowledge in academiccharacteristics for its stage of development. Reform of basic college English teaching, the teacher is still teaching main body, is the teaching oflanguage knowledge, since teachers play an important role in language teaching, the teacher wants to penetrate cultural knowledge in teachingand we must strengthen their own culture. Under this basis, this paper proposes the novel ideals on the related issues that will be meaningful andinnovative.
基金The National Science Foundation of China under Grant
文摘Doped micro-crystalline silicon films are deposited at temperatures as low as 400 ℃ by the catalytic chemical vapor deposition method using a silane and hydrogen gas mixture. Electrical properties such as the carrier concentration and the Hall mobility are investigated for various measuring temperatures. It is found that the grains of micro-crystalline silicon are preferentially oriented along the (220) direction , and that the Hall mobility is larger than 8 cm 2·V -1 ·s -1 , the carrier concentration is about 1×10 17 cm -1 ～1×10 19 cm -3 at room temperature.
文摘. A dialect refers to a local variation of a language which is distinguished fi＇om variants of the same language in grammar, lexis, or pronuneiation. A dialect plays an important role in second language learning. It can be a positive element as well as negative one in second language learning. Pingdu dialect as a kind of mandarin variation has its own structure and pronunciation rules. By contrastive analysis, we study the negative transfer of Pingdu Dialect on English pronunciation. We mainly concentrate on how two initials ＂s＂ and ＂z＂ in pinyin which sound like two English consonants/0 /and/6/influence the pronunciation of English consonants/s/and/z/. We also fred the countermeasures to overcome negative transfer of dialect on the acquisition of English pronunciation, thereby helping EFL learners in certain area of China acquire accurate English pronuneiations and enhance the ability of intercultural eommunication.
文摘The negative pragmatic transfer in second language acquisition has been seen as the major cause of pragmatic failure. In fact, the constant experiencing of negative pragmatic transfer is an active process of learning. The paper investigates the characteristics and classification of the negative pragmatic transfer so that people will have an objective attitude towards it. The author also provides suggestions and strategies so as to help the foreign language learners to establish the confidence in the foreign language study and intercultural communication.
基金National Key Research and Development Program of China(Nos.2022YFB4700600 and 2022YFB4700605)National Natural Science Foundation of China(Nos.61771123 and 62171116)+1 种基金Fundamental Research Funds for the Central UniversitiesGraduate Student Innovation Fund of Donghua University,China(No.CUSF-DH-D-2022044)。
文摘Defect detection is vital in the nonwoven material industry,ensuring surface quality before producing finished products.Recently,deep learning and computer vision advancements have revolutionized defect detection,making it a widely adopted approach in various industrial fields.This paper mainly studied the defect detection method for nonwoven materials based on the improved Nano Det-Plus model.Using the constructed samples of defects in nonwoven materials as the research objects,transfer learning experiments were conducted based on the Nano DetPlus object detection framework.Within this framework,the Backbone,path aggregation feature pyramid network(PAFPN)and Head network models were compared and trained through a process of freezing,with the ultimate aim of bolstering the model's feature extraction abilities and elevating detection accuracy.The half-precision quantization method was used to optimize the model after transfer learning experiments,reducing model weights and computational complexity to improve the detection speed.Performance comparisons were conducted between the improved model and the original Nano Det-Plus model,YOLO,SSD and other common industrial defect detection algorithms,validating that the improved methods based on transfer learning and semi-precision quantization enabled the model to meet the practical requirements of industrial production.
