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
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
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
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
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
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
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
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
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
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
The seismic behavior of a partially filled rigid rectangular liquid tank is investigated under short-and longduration ground motions.A finite element model is developed to analyze the liquid domain by using four-noded...The seismic behavior of a partially filled rigid rectangular liquid tank is investigated under short-and longduration ground motions.A finite element model is developed to analyze the liquid domain by using four-noded quadrilateral elements.The competency of the model is verified with the available results.Parametric studies are conducted for the dynamic parameters of the base-isolated tank,using a lead rubber bearing to evaluate the optimum damping and time period of the isolator.The application of base isolation has reduced the total and impulsive hydrodynamic components of pressure by 80 to 90 percent,and base shear by 15 to 95 percent,depending upon the frequency content and duration of the considered earthquakes.The sloshing amplitude of the base-isolated tank is reduced by 18 to 94 percent for most of the short-duration earthquakes,while it is increased by 17 to 60 percent for the majority of the long-duration earthquakes.Furthermore,resonance studies are carried out through a long-duration harmonic excitation to obtain the dynamic behavior of non-isolated and isolated tanks,using a nonlinear sloshing model.The seismic responses of the base-isolated tank are obtained as higher when the excitation frequency matches the fundamental sloshing frequency rather than the isolator frequency.展开更多
The load-bearing performance(LBP)of pumpable supports(PPS)is crucial for the stability of longwall pre-driven recovery room(PRR)surrounding rock.However,the unbalanced bearing coefficient(UBC)of the PPS(undertaking un...The load-bearing performance(LBP)of pumpable supports(PPS)is crucial for the stability of longwall pre-driven recovery room(PRR)surrounding rock.However,the unbalanced bearing coefficient(UBC)of the PPS(undertaking unequal load along the mining direction)has not been investigated.A mechanical model of the PRR was established,considering the main roof cantilever beam structure,to derive an assessment formula for the load,the failure criteria,and the UBC of the PPS.Subsequently,the generation mechanisms,and influencing factors of the UBC were revealed.Global sensitivity analysis shows that the main roof hanging length(l_(2))and the spacing between the PPS(r)significantly impact the UBC.A novel design of the PPS and the coupling control technology were proposed and applied to reduce the UBC of the PPS in the adjacent longwall PRR.Monitor results showed no failure of the PPS at the test site,with the UBC(ζ)reduced to 1.1 consistent with the design value(1.15)basically,fully utilizing the collaborative LBP of the PPS.Finally,the maximum roof-to-floor convergence of the PRR was 234 mm,effectively controlling the stability of the surrounding rock of the PRR and ensuring the mining equipment recovery.展开更多
Fluid lubricated bearings have been widely adopted as support components for high-end equipment in metrology,semiconductor devices,aviation,strategic defense,ultraprecision manufacturing,medical treatment,and power ge...Fluid lubricated bearings have been widely adopted as support components for high-end equipment in metrology,semiconductor devices,aviation,strategic defense,ultraprecision manufacturing,medical treatment,and power generation.In all these applications,the equipment must deliver extreme working performances such as ultraprecise movement,ultrahigh rotation speed,ultraheavy bearing loads,ultrahigh environmental temperatures,strong radiation resistance,and high vacuum operation,which have challenged the design and optimization of reliable fluid lubricated bearings.Breakthrough of any related bottlenecks will promote the development course of high-end equipment.To promote the advancement of high-end equipment,this paper reviews the design and optimization of fluid lubricated bearings operated at typical extreme working performances,targeting the realization of extreme working performances,current challenges and solutions,underlying deficiencies,and promising developmental directions.This paper can guide the selection of suitable fluid lubricated bearings and optimize their structures to meet their required working performances.展开更多
Predictive maintenance has emerged as an effective tool for curbing maintenance costs,yet prevailing research predominantly concentrates on the abnormal phases.Within the ostensibly stable healthy phase,the reliance o...Predictive maintenance has emerged as an effective tool for curbing maintenance costs,yet prevailing research predominantly concentrates on the abnormal phases.Within the ostensibly stable healthy phase,the reliance on anomaly detection to preempt equipment malfunctions faces the challenge of sudden anomaly discernment.To address this challenge,this paper proposes a dual-task learning approach for bearing anomaly detection and state evaluation of safe regions.The proposed method transforms the execution of the two tasks into an optimization issue of the hypersphere center.By leveraging the monotonicity and distinguishability pertinent to the tasks as the foundation for optimization,it reconstructs the SVDD model to ensure equilibrium in the model’s performance across the two tasks.Subsequent experiments verify the proposed method’s effectiveness,which is interpreted from the perspectives of parameter adjustment and enveloping trade-offs.In the meantime,experimental results also show two deficiencies in anomaly detection accuracy and state evaluation metrics.Their theoretical analysis inspires us to focus on feature extraction and data collection to achieve improvements.The proposed method lays the foundation for realizing predictive maintenance in a healthy stage by improving condition awareness in safe regions.展开更多
Due to the uneven seabed and heaving of soil during pumping,incomplete soil plugs may occur during the installation of bucket foundations,and the impacts on the bearing capacities of bucket foundations need to be eval...Due to the uneven seabed and heaving of soil during pumping,incomplete soil plugs may occur during the installation of bucket foundations,and the impacts on the bearing capacities of bucket foundations need to be evaluated.In this paper,the contact ratio(the ratio of the top diameter of the soil plug to the diameter of the bucket)and the soil plug ratio(the ratio of the soil heave height to the skirt height)are defined to describe the shape and size of the incomplete soil plug.Then,finite element models are established to investigate the bearing capacities of bucket foundations with incomplete soil plugs and the influences of the contact ratios,and the soil plug ratios on the bearing capacities are analyzed.The results show that the vertical bearing capacity of bucket foundations in homogeneous soil continuously improves with the increase of the contact ratio.However,in normally consolidated soil,the vertical bearing capacity barely changes when the contact ratio is smaller than 0.75,while the bearing capacity suddenly increases when the contact ratio increases to 1 due to the change of failure mode.The contact ratio hardly affects the horizontal bearing capacity of bucket foundations.Moreover,the moment bearing capacity improves with the increase of the contact ratio for small aspect ratios,but hardly varies with increasing contact ratio for aspect ratios larger than 0.5.Consequently,the reduction coefficient method is proposed based on this analysis to calculate the bearing capacities of bucket foundations considering the influence of incomplete soil plugs.The comparison results show that the proposed reduction coefficient method can be used to evaluate the influences of incomplete soil plug on the bearing capacities of bucket foundations.展开更多
Bear bile has been a valuable and effective medicinal material in traditional Chinese medicine(TCM)for over 13 centuries.However,the current practice of obtaining it through bear farming is under scrutiny for its adve...Bear bile has been a valuable and effective medicinal material in traditional Chinese medicine(TCM)for over 13 centuries.However,the current practice of obtaining it through bear farming is under scrutiny for its adverse impact on bear welfare.Here,we present a new approach for creating artificial bear bile(ABB)as a high-quality and sustainable alternative to natural bear bile.This study addresses the scientific challenges of creating bear bile alternatives through interdisciplinary collaborations across various fields,including resources,chemistry,biology,medicine,pharmacology,and TCM.A comprehensive efficacy assessment system that bridges the gap between TCM and modern medical terminology has been established,allowing for the systematic screening of therapeutic constituents.Through the utilization of chemical synthesis and enzyme engineering technologies,our research has achieved the environmentally friendly,large-scale production of bear bile therapeutic compounds,as well as the optimization and recomposition of ABB formulations.The resulting ABB not only closely resembles natural bear bile in its composition but also offers advantages such as consistent product quality,availability of raw materials,and independence from threatened or wild resources.Comprehensive preclinical efficacy evaluations have demonstrated the equivalence of the therapeutic effects from ABB and those from commercially available drained bear bile(DBB).Furthermore,preclinical toxicological assessment and phase I clinical trials show that the safety of ABB is on par with that of the currently used DBB.This innovative strategy can serve as a new research paradigm for developing alternatives for other endangered TCMs,thereby strengthening the integrity and sustainability of TCM.展开更多
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
To address the common issues of wrinkling,tearing,and uneven wall thickness in the actual sheet metal stamp-ing process of the outer ring of needle roller bearings,this study analyzes critical technical indicators suc...To address the common issues of wrinkling,tearing,and uneven wall thickness in the actual sheet metal stamp-ing process of the outer ring of needle roller bearings,this study analyzes critical technical indicators such asforming limits,thickness distribution,and principal strains in the forming process in detail.Three-dimensionalmodels of the concave and convex dies were constructed.The effects of different process parameters,includingstamping speed,edge pressure,sheet metal thickness,and friction coefficient,on the quality of the forming partswere investigated by varying these parameters.Subsequently,the orthogonal experimental method was used todetermine an optimal experimental group from multiple sets of experiments.It was found that under the processparameters of a stamping speed of 3000 mm/s,edge pressure of 2000 N,sheet metal thickness of 0.9 mm,andfriction coefficient of 0.125,the forming quality of the outer ring of the bearing is ideal.展开更多
文摘孩子们喜欢故事,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。
文摘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.
文摘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.
文摘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.
文摘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.
文摘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.
基金Key Scientific Research Foundation of Educational Committee of Sichuan Province (No. 2004 A101) and Key Discipline Construction Project in Sichuan Province (No. SZD0420)
文摘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.
基金supported by Structural Funds of EU Project of the Agency of the Ministry of Education,Science,Research and Sport of the Slovak Republic,Bratislava,ITMS No.26110230078
文摘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.
基金financially supported by the National Natural Science Foundation of China (No.52174297)。
文摘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.
基金supported by the National Natural Science Foundation of China(Nos.51922023,61874011)Fundamental Research Funds for the Central Universities(E1EG6804)
文摘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.
文摘The seismic behavior of a partially filled rigid rectangular liquid tank is investigated under short-and longduration ground motions.A finite element model is developed to analyze the liquid domain by using four-noded quadrilateral elements.The competency of the model is verified with the available results.Parametric studies are conducted for the dynamic parameters of the base-isolated tank,using a lead rubber bearing to evaluate the optimum damping and time period of the isolator.The application of base isolation has reduced the total and impulsive hydrodynamic components of pressure by 80 to 90 percent,and base shear by 15 to 95 percent,depending upon the frequency content and duration of the considered earthquakes.The sloshing amplitude of the base-isolated tank is reduced by 18 to 94 percent for most of the short-duration earthquakes,while it is increased by 17 to 60 percent for the majority of the long-duration earthquakes.Furthermore,resonance studies are carried out through a long-duration harmonic excitation to obtain the dynamic behavior of non-isolated and isolated tanks,using a nonlinear sloshing model.The seismic responses of the base-isolated tank are obtained as higher when the excitation frequency matches the fundamental sloshing frequency rather than the isolator frequency.
基金financial support provided by the Xinjiang Uygur Autonomous Region Key R&D Project Task Special-Department and Department Linkage Project(No.2022B01051)Major Project of Regional Joint Foundation of China(No.U21A20107)+1 种基金Hunan Provincial Natural Science Foundation of China(No.2024JJ4021)the Xinjiang Uygur Autonomous Region Tianchi Introduction Plan(No.2024XGYTCYC03)。
文摘The load-bearing performance(LBP)of pumpable supports(PPS)is crucial for the stability of longwall pre-driven recovery room(PRR)surrounding rock.However,the unbalanced bearing coefficient(UBC)of the PPS(undertaking unequal load along the mining direction)has not been investigated.A mechanical model of the PRR was established,considering the main roof cantilever beam structure,to derive an assessment formula for the load,the failure criteria,and the UBC of the PPS.Subsequently,the generation mechanisms,and influencing factors of the UBC were revealed.Global sensitivity analysis shows that the main roof hanging length(l_(2))and the spacing between the PPS(r)significantly impact the UBC.A novel design of the PPS and the coupling control technology were proposed and applied to reduce the UBC of the PPS in the adjacent longwall PRR.Monitor results showed no failure of the PPS at the test site,with the UBC(ζ)reduced to 1.1 consistent with the design value(1.15)basically,fully utilizing the collaborative LBP of the PPS.Finally,the maximum roof-to-floor convergence of the PRR was 234 mm,effectively controlling the stability of the surrounding rock of the PRR and ensuring the mining equipment recovery.
基金supported by the National Natural Science Foundations of China under Grant Nos.52206123,52075506,52205543,52322510,52275470 and 52105129Science and Technology Planning Project of Sichuan Province under Grant No.2021YJ0557+2 种基金Natural Science Foundation of Sichuan Province under Grant No.2023NSFSC1947Presidential Foundation of China Academy of Engineering PhysicsGrant No.YZJJZQ2022009。
文摘Fluid lubricated bearings have been widely adopted as support components for high-end equipment in metrology,semiconductor devices,aviation,strategic defense,ultraprecision manufacturing,medical treatment,and power generation.In all these applications,the equipment must deliver extreme working performances such as ultraprecise movement,ultrahigh rotation speed,ultraheavy bearing loads,ultrahigh environmental temperatures,strong radiation resistance,and high vacuum operation,which have challenged the design and optimization of reliable fluid lubricated bearings.Breakthrough of any related bottlenecks will promote the development course of high-end equipment.To promote the advancement of high-end equipment,this paper reviews the design and optimization of fluid lubricated bearings operated at typical extreme working performances,targeting the realization of extreme working performances,current challenges and solutions,underlying deficiencies,and promising developmental directions.This paper can guide the selection of suitable fluid lubricated bearings and optimize their structures to meet their required working performances.
基金Supported by Sichuan Provincial Key Research and Development Program of China(Grant No.2023YFG0351)National Natural Science Foundation of China(Grant No.61833002).
文摘Predictive maintenance has emerged as an effective tool for curbing maintenance costs,yet prevailing research predominantly concentrates on the abnormal phases.Within the ostensibly stable healthy phase,the reliance on anomaly detection to preempt equipment malfunctions faces the challenge of sudden anomaly discernment.To address this challenge,this paper proposes a dual-task learning approach for bearing anomaly detection and state evaluation of safe regions.The proposed method transforms the execution of the two tasks into an optimization issue of the hypersphere center.By leveraging the monotonicity and distinguishability pertinent to the tasks as the foundation for optimization,it reconstructs the SVDD model to ensure equilibrium in the model’s performance across the two tasks.Subsequent experiments verify the proposed method’s effectiveness,which is interpreted from the perspectives of parameter adjustment and enveloping trade-offs.In the meantime,experimental results also show two deficiencies in anomaly detection accuracy and state evaluation metrics.Their theoretical analysis inspires us to focus on feature extraction and data collection to achieve improvements.The proposed method lays the foundation for realizing predictive maintenance in a healthy stage by improving condition awareness in safe regions.
基金financially supported by the National Science Fund for Distinguished Young Scholars of China(Grant No.51825904)the Research on the Form,Design Method and Weathering Resistance of Key Components of Novel Floating Support Structures for Offshore Photovoltaics(Grant No.2022YFB4200701).
文摘Due to the uneven seabed and heaving of soil during pumping,incomplete soil plugs may occur during the installation of bucket foundations,and the impacts on the bearing capacities of bucket foundations need to be evaluated.In this paper,the contact ratio(the ratio of the top diameter of the soil plug to the diameter of the bucket)and the soil plug ratio(the ratio of the soil heave height to the skirt height)are defined to describe the shape and size of the incomplete soil plug.Then,finite element models are established to investigate the bearing capacities of bucket foundations with incomplete soil plugs and the influences of the contact ratios,and the soil plug ratios on the bearing capacities are analyzed.The results show that the vertical bearing capacity of bucket foundations in homogeneous soil continuously improves with the increase of the contact ratio.However,in normally consolidated soil,the vertical bearing capacity barely changes when the contact ratio is smaller than 0.75,while the bearing capacity suddenly increases when the contact ratio increases to 1 due to the change of failure mode.The contact ratio hardly affects the horizontal bearing capacity of bucket foundations.Moreover,the moment bearing capacity improves with the increase of the contact ratio for small aspect ratios,but hardly varies with increasing contact ratio for aspect ratios larger than 0.5.Consequently,the reduction coefficient method is proposed based on this analysis to calculate the bearing capacities of bucket foundations considering the influence of incomplete soil plugs.The comparison results show that the proposed reduction coefficient method can be used to evaluate the influences of incomplete soil plug on the bearing capacities of bucket foundations.
基金supported by the Major Program of National Natural Science Foundation of China(T2192970-T2192974)the CAMS Innovation Fund for Medical Sciences(CIFMS,2021-I2M-1-027).
文摘Bear bile has been a valuable and effective medicinal material in traditional Chinese medicine(TCM)for over 13 centuries.However,the current practice of obtaining it through bear farming is under scrutiny for its adverse impact on bear welfare.Here,we present a new approach for creating artificial bear bile(ABB)as a high-quality and sustainable alternative to natural bear bile.This study addresses the scientific challenges of creating bear bile alternatives through interdisciplinary collaborations across various fields,including resources,chemistry,biology,medicine,pharmacology,and TCM.A comprehensive efficacy assessment system that bridges the gap between TCM and modern medical terminology has been established,allowing for the systematic screening of therapeutic constituents.Through the utilization of chemical synthesis and enzyme engineering technologies,our research has achieved the environmentally friendly,large-scale production of bear bile therapeutic compounds,as well as the optimization and recomposition of ABB formulations.The resulting ABB not only closely resembles natural bear bile in its composition but also offers advantages such as consistent product quality,availability of raw materials,and independence from threatened or wild resources.Comprehensive preclinical efficacy evaluations have demonstrated the equivalence of the therapeutic effects from ABB and those from commercially available drained bear bile(DBB).Furthermore,preclinical toxicological assessment and phase I clinical trials show that the safety of ABB is on par with that of the currently used DBB.This innovative strategy can serve as a new research paradigm for developing alternatives for other endangered TCMs,thereby strengthening the integrity and sustainability of TCM.
基金supported by the National Natural Science Foundation of China-Liaoning Joint Fund Key Project(Grant No.U1908222)the National Natural Science Foundation of China Youth Science Fund(Grant No.52104087).
文摘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.
基金supported by the China Postdoctoral Science Foundation(Grant No.2022M721395)the National Natural Science Foundation of China(Grant No.72072089).
文摘To address the common issues of wrinkling,tearing,and uneven wall thickness in the actual sheet metal stamp-ing process of the outer ring of needle roller bearings,this study analyzes critical technical indicators such asforming limits,thickness distribution,and principal strains in the forming process in detail.Three-dimensionalmodels of the concave and convex dies were constructed.The effects of different process parameters,includingstamping speed,edge pressure,sheet metal thickness,and friction coefficient,on the quality of the forming partswere investigated by varying these parameters.Subsequently,the orthogonal experimental method was used todetermine an optimal experimental group from multiple sets of experiments.It was found that under the processparameters of a stamping speed of 3000 mm/s,edge pressure of 2000 N,sheet metal thickness of 0.9 mm,andfriction coefficient of 0.125,the forming quality of the outer ring of the bearing is ideal.