期刊文献+
共找到1,388篇文章
< 1 2 70 >
每页显示 20 50 100
《Goldilocks and the three bears》教学实录
1
作者 钱希洁 《江苏教育研究(实践)(B版)》 2016年第9期14-17,共4页
孩子们喜欢故事,老师也喜欢故事,因此,通过故事的方式引导小学生学习英语已经成为当前一种有效的英语教学方式。《义务教育英语课程标准》(2011年版)在"语言技能"二级要求中就英语故事教学做出如下描述:"能听懂简单的配... 孩子们喜欢故事,老师也喜欢故事,因此,通过故事的方式引导小学生学习英语已经成为当前一种有效的英语教学方式。《义务教育英语课程标准》(2011年版)在"语言技能"二级要求中就英语故事教学做出如下描述:"能听懂简单的配图小故事,能在教师的帮助下和图片的提示下描述或讲述简单的小故事,能正确朗读所学故事或短文,能在教师的帮助下表演小故事或小短剧。"为此,当前很多小学英语教材都在权重板块设置了"Story Time",旨在通过故事的方式引导学生开展富有趣味的英语学习活动。确实,故事教学给小学英语课堂带来了新的活力、新的气象,然而,当一些英语小故事被抹上过于浓重的"教学味"的时候,它们在学生眼中便失去了原有的魅力,所谓的"Story Time"也就或多或少地缺失了故事该有的滋味。因此,如何使故事教学更具有故事的味儿,也是我们当今面对的一个重要课题。多年来,钱希洁老师对此进行了深入的实践与探索,本文主要以她执教的译林出版社出版的《义务教育教科书·英语》(五年级上册)Unit 1 Story time板块中的故事"Goldilocks and the three bears"教学中的几个片段为例,阐述了她对小学英语故事教学的思考,旨在与广大同行朋友们探讨:如何使小学英语故事教学散发出更为浓郁的故事味。我们相信,这样的探讨对于其它学科的教学,也有一定的借鉴意义。 展开更多
关键词 小学英语 bears 小学生学习 五年级 钱希 译林出版社 THINK 新单词 STORY 简笔画
下载PDF
WHY DO BEARS HAVE SHORT TAILS?
2
作者 张敏 《中学生英语(初中版)》 2006年第7期12-12,共1页
关键词 熊爸爸 WHY DO bears HAVE SHORT TAILS
下载PDF
热闹背后的冷思考——译林版教材5A Unit 1 Goldilocks and the three bears教学反思
3
作者 陆坊庆 《教学月刊(小学版)(综合)》 2015年第11期8-9,共2页
作为一名由初中改教小学的英语教师,深知在教学手段和教学方法方面中小学的英语课堂会有很多的差异,小学课堂应该会比初中课堂更显得热闹,小学生的知识习得应该是在活动中自然习得,因此笔者力求创设一种"热闹"的课堂氛围。
关键词 bears 小学课堂 自然习得 知识习得 课堂气氛 译林 CLASSROOM 语言操练 教参 语言学习
下载PDF
Policy Stimulus Bears Fruit
4
《ChinAfrica》 2018年第9期53-53,共1页
In the second quarter of 2018, the Chinese economy grew at 6.7 percent which is in line with expectations and marginally slower than the 6.8-percent growth recorded in the previous three quarters. Growth during the fi... In the second quarter of 2018, the Chinese economy grew at 6.7 percent which is in line with expectations and marginally slower than the 6.8-percent growth recorded in the previous three quarters. Growth during the first half this year also stands at 6.7 percent. Amidst the ongoing trade war with the United States, as of July 27, the renminbi (RMB) has fallen 8.2 percent against the dollar since April 2. Having fallen below 3,000 in June for the first time in two years. 展开更多
关键词 Policy Stimulus bears Fruit
下载PDF
Cooperation That Bears Fruit
5
《ChinAfrica》 2018年第2期24-25,共2页
The Johannesburg Summit of the Forum on China-Africa Cooperation held in South Africa in December 2015has raised the level of agricultural cooperation between China and African countries,as evidenced by the achievemen... The Johannesburg Summit of the Forum on China-Africa Cooperation held in South Africa in December 2015has raised the level of agricultural cooperation between China and African countries,as evidenced by the achievements made by Chinese agricultural missions working on the continent. 展开更多
关键词 Cooperation That bears Fruit
下载PDF
MITIGATING THE DAMAGE OF BROWN BEARS IN MARYO TOWNSHIP
6
作者 Lan Zhoujia 《China's Tibet》 2018年第1期33-37,共5页
The need for the mitigation of brown bears has become so severe that many nomads have given up repairing their houses in Maryo Township’s Mendang Village(also named the First Administrative Village),a remote place lo... The need for the mitigation of brown bears has become so severe that many nomads have given up repairing their houses in Maryo Township’s Mendang Village(also named the First Administrative Village),a remote place located in the southwestern section of the Changtang National Nature Reserve(CNNR).Only part of the village belongs to Serling Tso Nature Reserve. 展开更多
关键词 MITIGATING THE DAMAGE OF BROWN bears IN MARYO TOWNSHIP
下载PDF
SEPARATING BROWN AND BLACK BEARS IN NORTHEAST CHINA USING TOOTH MEASUREMENTS
7
作者 姜兆文 郑红 +1 位作者 王玉玺 张淑云 《Journal of Northeast Forestry University》 SCIE CAS CSCD 1995年第2期58-60,共3页
An expeditious method for ascertaining species between black bear (Selenarctos thibetanus G. cuiver) and brown bear (Ursus arctos Linnaeus) was developed using tooth measurements from previously identified specimens. ... An expeditious method for ascertaining species between black bear (Selenarctos thibetanus G. cuiver) and brown bear (Ursus arctos Linnaeus) was developed using tooth measurements from previously identified specimens. The measurement and analysis on 18 tooth measurement indexes (i.e. T1. Length of Pm1-Pm4, T2. L. of M1-M3, T3. M1L., T4. M1 width, T5. M2L., T6. M2W., T7.M3L., T8. M3W., T9. L. of C1 alveolus, T10. W. of C1 alveolus, T11. L. of C1-M2, T12. L. of Pm4 M2,T13.M1L., T14. M1W., T15. M2L., T16. M2W., T17.L. of C1 alveolus, T18. W. of C1 alveolus) of 59 skulls (black bears 25, brown bears 34) indicates that there are significant or the most significant difference between two species in every indexes, however T1, T9, T10, T17 and T18 are not suitable for species discriminator because of their high percent of overlap. The efficient species discriminators and standards (mm) are as follows T2(63.0), T3(22.0), T4(10.2), T5(23.8), T6(13.6), T7(18.0), T8(13.5), T11(110.0),T12(66.0), T13(20. 1), T14(15.8), T15(33.0) and T16(17.3). Those who are less than or equal to standard are classified to black bear, the others are brown bear. The method is very convenient and useful with high reliability. Their lowest accuracy percent are 95.0%, most of them over 97%. Different indexes will be chosen refer to the degree of specimen destroyed. 展开更多
关键词 BLACK BEAR (Selenarctos thibetanus) BROWN BEAR (Ursus arctos) TOOTH measurement SEPARATING
下载PDF
Behavior of Brown Bears (Ursus arctos) in Captivity during Mating Season
8
作者 徐利 李力 杨秀娟 《Journal of Forestry Research》 SCIE CAS CSCD 1997年第2期115-116,共2页
From 1991 to 1992, we observed behavior of 7 brown bears (5 females, 2 males) in mating season. Re-Sults showed tkat the oertrus of brown bears was mainly from May to July. The oeStrus ofmost individuals occwred at th... From 1991 to 1992, we observed behavior of 7 brown bears (5 females, 2 males) in mating season. Re-Sults showed tkat the oertrus of brown bears was mainly from May to July. The oeStrus ofmost individuals occwred at theend of May and the beginning of June. There were some differences in the oestrus among individuals. Average duration ofthe oestrus 30.8 days (16-50 days). The mating behavior was mainly observed during 8.00-9.00 a.m., and 15.00-16.00p.m.. Rest and sleep were the next behavior after mating for most bears, especially for male bears. All bears had poor appe-the. The Pattern and process of a successful mating was that a male bear approached a female, smelled the pudendum of thefemale, climbed on female hip, mated, parted and rested. Oestrus females approached males sometimes. 展开更多
关键词 BEHAVIOR BROWN BEAR MATING SEASON
下载PDF
Myocardial enzyme activities of black bears and comparison with those of human beings
9
作者 侯万儒 《Journal of Chongqing University》 CAS 2005年第2期117-120,共4页
According to the principle of enzyme reaction rate, healthy pent black bears’ myocardial enzyme activity is assayed by visual colorimetry and compared with that of healthy human beings. The determination at 37 °... According to the principle of enzyme reaction rate, healthy pent black bears’ myocardial enzyme activity is assayed by visual colorimetry and compared with that of healthy human beings. The determination at 37 °C and the statistic analysis of the experimental data work out the following findings. For male black bears, the average CK activity is 163.20 U/L, the confidence interval of its expected value (127.70 to 198.70) U/L, and the coefficient of variation 39.2%; the average CK-MB activity 21.62 U/L, the confidential interval (17.72 to 25.51) U/L, and the coefficient of variation 34.26%; the average LDH activity 604.20 U/L, the confidence interval (524.56 to 683.83) U/L, and the coefficient of variation 23.80%; the average HBDH activity 516.70 U/L, the confidence interval (453.06 to 580.34) U/L, and the coefficient of variation 22.24%; the average GOT activity 69.70 U/L, the confidence interval (60.21 to 79.19) U/L, and the coefficient of variation 24.59%. For female black bears, the average CK activity is 145.50 U/L, the confidence interval (114.59 to 176.21) U/L, and the coefficient of variation 38.27%; the average CK-MB activity 18.84 U/L, the confidence interval (14.64 to 23.04) U/L, and the coefficient of variation 40.34%; the average LDH activity 563.70 U/L, the confidence interval (473.80 to 652.60) U/L, and the coefficient of variation 28.80%; the average of HBDH activity 475.50 U/L, the confidence interval (412.10 to 538.40) U/L, and the coefficient of variation 24.07%; the average of GOT activity is 62.37 U/L, the confidential interval (52.54 to 72.20) U/L, and the coefficient of variation 28.46%. The male black bear’s average myocardium enzyme activities are slightly higher than those of the female. But the statistical results indicate that the difference is not significant. 展开更多
关键词 black bear (Ursus thibetanus) myocardium enzyme enzyme activity
下载PDF
Genetic analysis for geographic isolation comparison of brown bears living in the periphery of the Western Carpathians Mountains with bears living in other areas
10
作者 Jan Graban Jana Kiskova +1 位作者 Pavol Pepich Robin Rigg 《Open Journal of Genetics》 2013年第3期174-182,共9页
Populations of the European brown bear (Ursus arctos L.) differ substantially in size, degree of geographic isolation and level of genetic diversity. Present patterns result from phylogeographic processes and profound... Populations of the European brown bear (Ursus arctos L.) differ substantially in size, degree of geographic isolation and level of genetic diversity. Present patterns result from phylogeographic processes and profound human intervention. We assessed the genetic variability of a subpopulation of brown bears near the periphery of their range in the Western Carpathian Mountains and compared their genetic properties with those of bears in the core of the same population and elsewhere. Samples were collected non-invasively in 2007-2008 and2010 in Strázovské Vrchy Protected Landscape Area (PLA) in Slovakia (included in the NATURA 2000 networking programme). Seven polymorphic microsatellite loci (UaMU26, UaMU64, G10B, G1D, G10L, UaMU50 and UaMU51) were amplified using a nested PCR in order to assess the following parameters: variability, allelic combinations, heterozygosity, number of alleles and inbreeding coefficient. Sufficient brown bear DNA for analysis was obtained from 57 out of 140 samples (41%), among which 45 different genotypes were identified. Loci had a mean of 2.71 ± 0.76 alleles. Average observed heterozygosity was 0.59. The inbreeding coefficient was negative for all but one of the analysed loci (2007-2008). In the year 2010 was negative three of seven loci. These results imply that gene flow with other parts of the population has been maintained in the reduced level and the isolation level of bears in the study area was not so low. Nevertheless, the genetic variability of bears in Strázovské Vrchy PLA was lower than that reported from other localities in the Carpathian Mountains. The results are discussed in the context of behavioural ecology and conservation genetics. 展开更多
关键词 Carpathian Mountains European Brown Bear Ursus arctos L. Genetic Diversity Microsatellite Markers Non-Invasive Sampling
下载PDF
Bearing Fault Diagnosis Based on the Markov Transition Field and SE-IShufflenetV2 Model
11
作者 Chaozhi Cai Tiexin Xu +1 位作者 Jianhua Ren Yingfang Xue 《Structural Durability & Health Monitoring》 EI 2025年第1期125-144,共20页
A bearing fault diagnosis method based on the Markov transitionfield(MTF)and SEnet(SE)-IShufflenetV2 model is proposed in this paper due to the problems of complex working conditions,low fault diagnosis accuracy,and poo... A bearing fault diagnosis method based on the Markov transitionfield(MTF)and SEnet(SE)-IShufflenetV2 model is proposed in this paper due to the problems of complex working conditions,low fault diagnosis accuracy,and poor generalization of rolling bearing.Firstly,MTF is used to encode one-dimensional time series vibration sig-nals and convert them into time-dependent and unique two-dimensional feature images.Then,the generated two-dimensional dataset is fed into the SE-IShufflenetV2 model for training to achieve fault feature extraction and classification.This paper selects the bearing fault datasets from Case Western Reserve University and Paderborn University to experimentally verify the effectiveness and superiority of the proposed method.The generalization performance of the proposed method is tested under the variable load condition and different signal-to-noise ratios(SNRs).The experimental results show that the average accuracy of the proposed method under different working conditions is 99.2%without adding noise.The accuracy under different working conditions from 0 to 1 HP is 100%.When the SNR is 0 dB,the average accuracy of the proposed method can still reach 98.7%under varying working conditions.Therefore,the bearing fault diagnosis method proposed in this paper is characterized by high accuracy,strong anti-noise ability,and generalization.Moreover,the proposed method can also overcome the influence of variable working conditions on diagnosis accuracy,providing method support for the accurate diagnosis of bearing faults under strong noise and variable working conditions. 展开更多
关键词 Bearings Markov transitionfield SE-IShufflenetV2
下载PDF
Life-Cycle Bearing Capacity for Pre-Stressed T-beams Based on Full-Scale Destructive Test
12
作者 Yushan Ye Tao Gao +4 位作者 Liankun Wang Junjie Ma Yingchun Cai Heng Liu Xiaoge Liu 《Structural Durability & Health Monitoring》 EI 2025年第1期145-166,共22页
To investigate the evolution of load-bearing characteristics of pre-stressed beams throughout their service life and to provide a basis for accurately assessing the actual working state of damaged pre-stressed concret... To investigate the evolution of load-bearing characteristics of pre-stressed beams throughout their service life and to provide a basis for accurately assessing the actual working state of damaged pre-stressed concrete T-beams,destructive tests were conducted on full-scale pre-stressed concrete beams.Based on the measurement and ana-lysis of beam deflection,strain,and crack development under various loading levels during the research tests,combined with the verification coefficient indicators specified in the codes,the verification coefficients of bridges at different stages of damage can be examined.The results indicate that the T-beams experience complete,incom-plete linear,and non-linear stages during the destructive test process.In the complete linear elastic stage,both the deflection and bottom strain verification coefficients comply with the specifications,indicating a good structural load-bearing capacity no longer adheres to the code’s requirements.In the non-linear stage,both coefficients exhi-bit a sharp increase,resulting in a further decrease in the structure’s load-bearing capacity.According to the pro-visions of the current code,the beam can be in the incomplete linear stage when both values fall within the code’s specified range.The strain verification coefficient sourced from the compression zone at the bottom of theflange is not recommended for assessing the bridge’s load-bearing capacity. 展开更多
关键词 Pre-stressed T-beams whole process destructive test bearing capacity verification coefficient
下载PDF
A Place to Call Home——Rescued moon bears get to live a decent life
13
作者 YIN PUMIN 《Beijing Review》 2006年第24期30-31,共2页
On February 8, 2006, a piece of sad news came out of the Moon Bear Rescue Center in Chengdu, capital city of southwest China's Sichuan Province. Andrew, the first moon bear rescued by the Animals Asia Foundation, ... On February 8, 2006, a piece of sad news came out of the Moon Bear Rescue Center in Chengdu, capital city of southwest China's Sichuan Province. Andrew, the first moon bear rescued by the Animals Asia Foundation, which sponsors the center, died of liver cancer, thought to have arisen from the massive infec- 展开更多
关键词 A Place to Call Home Rescued moon bears get to live a decent life
原文传递
Student Detained for Pouring Acid on Bears
14
作者 杨光 《当代外语研究》 2002年第4期25-25,共1页
Yahoo,我最喜欢浏览的网站,Oddly Enough是我最喜欢的专栏之一。这个栏目绝少有中国故事。不料,刚刚开学,就在Yahoo上读到北京大学生在动物园“作孽”的故事。“作孽”者往熊身上泼洒硫酸,后果严重,但他竟然解释:Iwanted to test whethe... Yahoo,我最喜欢浏览的网站,Oddly Enough是我最喜欢的专栏之一。这个栏目绝少有中国故事。不料,刚刚开学,就在Yahoo上读到北京大学生在动物园“作孽”的故事。“作孽”者往熊身上泼洒硫酸,后果严重,但他竟然解释:Iwanted to test whether or not they really are stupid。但是,I wanted to ask whetheror not he really is stupid!】 展开更多
关键词 Student Detained for Pouring Acid on bears
原文传递
Wound healing during hibernation by black bears (Ursus americanus) in the wild: elicitation of reduced scar formation
15
作者 Paul A.IAIZZO Timothy G.LASKE +2 位作者 Henry J.HARLOW Carolyn B.McCLAY David L.GARSHELIS 《Integrative Zoology》 SCIE CSCD 2012年第1期48-60,共13页
Even mildly hypothermic body or limb temperatures can retard healing processes in mammals.Despite this,we observed that hibernating American black bears(Ursus americanus Pallas,1780)elicit profound abilities in mounti... Even mildly hypothermic body or limb temperatures can retard healing processes in mammals.Despite this,we observed that hibernating American black bears(Ursus americanus Pallas,1780)elicit profound abilities in mounting inflammatory responses to infection and/or foreign bodies.In addition,they resolve injuries during hibernation while maintaining mildly hypothermic states(30–35°C)and without eating,drinking,urinating or defecating.We describe experimental studies on free-ranging bears that document their abilities to completely resolve cutaneous cuts and punctures incurred during or prior to hibernation.We induced small,full-thickness cutaneous wounds(biopsies or incisions)during early denning,and re-biopsied sites 2–3 months later(near the end of denning).Routine histological methods were used to characterize these skin samples.All biopsied sites with respect to secondary intention(open circular biopsies)and primary intention(sutured sites)healed,with evidence of initial eschar(scab)formation,completeness of healed epidermis and dermal layers,dyskeratosis(inclusion cysts),and abilities to produce hair follicles.These healing abilities of hibernating black bears are a clear survival advantage to animals injured before or during denning.Bears are known to have elevated levels of hibernation induction trigger(delta-opioid receptor agonist)and ursodeoxycholic acid(major bile acid within plasma,mostly conjugated with taurine)during hibernation,which may relate to these wound-healing abilities.Further research as to the underlying mechanisms of wound healing during hibernation could have applications in human medicine.Unique approaches may be found to improve healing for malnourished,hypothermic,diabetic and elderly patients or to reduce scarring associated with burns and traumatic injuries. 展开更多
关键词 black bear denning hair growth HEALING HIBERNATION HISTOLOGY SCARRING
原文传递
Using machine learning to predict habitat suitability of sloth bears at multiple spatial scales
16
作者 Tahir Ali Rather Sharad Kumar Jamal Ahmad Khan 《Ecological Processes》 SCIE EI 2021年第1期634-645,共12页
Background:Habitat resources occur across the range of spatial scales in the environment.The environmental resources are characterized by upper and lower limits,which define organisms’distribution in their communitie... Background:Habitat resources occur across the range of spatial scales in the environment.The environmental resources are characterized by upper and lower limits,which define organisms’distribution in their communities.Animals respond to these resources at the optimal spatial scale.Therefore,multi-scale assessments are critical to identifying the correct spatial scale at which habitat resources are most influential in determining the specieshabitat relationships.This study used a machine learning algorithm random forest(RF),to evaluate the scaledependent habitat selection of sloth bears(Melursus ursinus)in and around Bandhavgarh Tiger Reserve,Madhya Pradesh,India.Results:We used 155 spatially rarified occurrences out of 248 occurrence records of sloth bears obtained from camera trap captures(n=36)and scats located(n=212)in the field.We calculated focal statistics for 13 habitat variables across ten spatial scales surrounding each presence-absence record of sloth bears.Large(>5000 m)and small(1000–2000 m)spatial scales were the most dominant scales at which sloth bears perceived the habitat features.Among the habitat covariates,farmlands and degraded forests were the essential patches associated with sloth bear occurrences,followed by sal and dry deciduous forests.The final habitat suitability model was highly accurate and had a very low out-of-bag(OOB)error rate.The high accuracy rate was also obtained using alternate validation matrices.Conclusions:Human-dominated landscapes are characterized by expanding human populations,changing landuse patterns,and increasing habitat fragmentation.Farmland and degraded habitats constitute~40%of the landform in the buffer zone of the reserve.One of the management implications may be identifying the highly suitable bear habitats in human-modified landscapes and integrating them with the existing conservation landscapes. 展开更多
关键词 Bandhavgarh Melursus ursinus MULTI-SCALE Habitat selection Random forest Sloth bear Species distribution models
原文传递
A GALLERY OF PEOPLE AND PLACES
17
《ChinAfrica》 2024年第12期12-13,共2页
BANGLADESH Fishermen participate in a fishing competition at dawn on 26 October CANADA Two polar bears are sighted in Churchill,Manitoba,on 4 November KENYA People dance at the Maa Cultural Festival in Samburu Nationa... BANGLADESH Fishermen participate in a fishing competition at dawn on 26 October CANADA Two polar bears are sighted in Churchill,Manitoba,on 4 November KENYA People dance at the Maa Cultural Festival in Samburu National Reserve on 8 November. 展开更多
关键词 FISHING bears RESERVE
下载PDF
Development and prospects of molten steel deoxidation in steelmaking process 被引量:3
18
作者 Zhongliang Wang Yanping Bao 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CSCD 2024年第1期18-32,共15页
In the long traditional process of steelmaking,excess oxygen is blown into the converter,and alloying elements are used for deoxidation.This inevitably results in excessive deoxidation of products remaining within the... In the long traditional process of steelmaking,excess oxygen is blown into the converter,and alloying elements are used for deoxidation.This inevitably results in excessive deoxidation of products remaining within the steel liquid,affecting the cleanliness of the steel.With the increasing requirements for steel performance,reducing the oxygen content in the steel liquid and ensuring its high cleanliness is necessary.After more than a hundred years of development,the total oxygen content in steel has been reduced from approximately 100×10^(-6)to approximately 10×10^(-6),and it can be controlled below 5×10^(-6)in some steel grades.A relatively stable and mature deoxidation technology has been formed,but further reducing the oxygen content in steel is no longer significant for improving steel quality.Our research team developed a deoxidation technology for bearing steel by optimizing the entire conventional process.The technology combines silicon–manganese predeoxidation,ladle furnace diffusion deoxidation,and vacuum final deoxidation.We successfully conducted industrial experiments and produced interstitial-free steel with natural decarbonization predeoxidation.Non-aluminum deoxidation was found to control the oxygen content in bearing steel to between 4×10^(-6) and 8×10^(-6),altering the type of inclusions,eliminating large particle Ds-type inclusions,improving the flowability of the steel liquid,and deriving a higher fatigue life.The natural decarbonization predeoxidation of interstitial-free steel reduced aluminum consumption and production costs and significantly improved the quality of cast billets. 展开更多
关键词 steel deoxidation DEOXIDIZER metallurgical equipment bearing steel IF steel
下载PDF
Ultra-Robust and High-Performance Rotational Triboelectric Nanogenerator by Bearing Charge Pumping 被引量:2
19
作者 Xianpeng Fu Yuhan Qin +6 位作者 Zhi Zhang Guoxu Liu Jie Cao Beibei Fan Zhaozheng Wang Zheng Wang Chi Zhang 《Energy & Environmental Materials》 SCIE EI CAS CSCD 2024年第2期343-349,共7页
As an emerging technology to convert environmental high-entropy energy into electrical energy,triboelectric nanogenerator(TENG)has great demands for further enhancing the service lifetime and output performance in pra... As an emerging technology to convert environmental high-entropy energy into electrical energy,triboelectric nanogenerator(TENG)has great demands for further enhancing the service lifetime and output performance in practical applications.Here,an ultra-robust and high-performance rotational triboelectric nanogenerator(R-TENG)by bearing charge pumping is proposed.The R-TENG composes of a pumping TENG(P-TENG),an output TENG(O-TENG),a voltage-multiplying circuit(VMC),and a buffer capacitor.The P-TENG is designed with freestanding mode based on a rolling ball bearing,which can also act as the rotating mechanical energy harvester.The output low charge from the P-TENG is accumulated and pumped to the non-contact O-TENG,which can simultaneously realize ultralow mechanical wear and high output performance.The matched instantaneous power of R-TENG is increased by 32 times under 300 r/min.Furthermore,the transferring charge of R-TENG can remain 95%during 15 days(6.4×10^(6)cycles)continuous operation.This work presents a realizable method to further enhance the durability of TENG,which would facilitate the practical applications of high-performance TENG in harvesting distributed ambient micro mechanical energy. 展开更多
关键词 bearing charge pumping triboelectric nanogenerators ultralow mechanical wear ultra-robust voltage-multiplying circuit
下载PDF
Optimizing support performances of bolt reaming and anchoring in a coal drift 被引量:1
20
作者 Wei Wang Yishan Pan +7 位作者 Yonghui Xiao Lianpeng Dai Xinping Zhang Yuheng Wang Xufeng Qin Yanfei Zhu Yan Liu Gang Li 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第10期3885-3906,共22页
In current practice of bolt reaming and anchoring of roadways in soft coal and rock mass,resin cartridges bend easily under the strong pushing and stirring of bolts,and the resin accumulates in the bolt-reamed area an... In current practice of bolt reaming and anchoring of roadways in soft coal and rock mass,resin cartridges bend easily under the strong pushing and stirring of bolts,and the resin accumulates in the bolt-reamed area and does not participate in the stirring.As a result,bolts encounter high drilling resistance and cannot reach the bottom of drillholes.The effective anchorage length is far less than the actual anchorage length.Bolts are not centered,and the shear is misaligned at the joint surface in the reaming area,which leads to cracking of the whole anchoring solid and large shear deformation of bolts.This study systematically analyzes the characteristics of roadway bolt reaming and anchoring.The influences of resin stirring force,bolt pull-out force,and reamingeanchoring solid strength on reamingeanchoring performance were analyzed theoretically.The main purpose is to develop a device that enhances reaming and anchoring.The mechanism through which the device strengthens the reamingeanchoring solid was analyzed theoretically.Numerical simulation and experiments were carried out to verify the improved performance of the small-pore reaming and anchoring using the proposed technology.The results showed that the stirring migration rate of the resin cartridge is greatly improved by adding the device to bolts.The reaction rate of the anchoring mixture,stirring pressure,pull-out force of the reaming and anchoring system,bolt concentricity,and shear and compressive strengths of the anchoring solid are also enhanced in the reaming area.This ensures that the resin cartridge in the reaming area is completely stirred,which greatly improves the shear resistance of the reamingeanchoring solid.Meanwhile,the drilling performance,torsional force,and stirring efficiency of bolts are maximized and prevail over those of conventional bolts. 展开更多
关键词 Bolt reaming Enhancement device Reamingeanchoring performance Strength of reamingeanchoring solid Bearing capacity
下载PDF
上一页 1 2 70 下一页 到第
使用帮助 返回顶部