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3D FINITE ELEMENT ANALYSIS OF THE DAMAGE EFFEcTS ON THE DENTAL cOMPOSITE SUBJEcT TO WATER SORPTION

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Acta Mechanica Solida Sinica 2006年第3期19卷 212-222页

作者： Tsui c.P. chow c.L. Department of Industrial and Systems Engineering The Hong Kong Polytechnic University Hong Kong ChinaDepartment of Mechanical EngineeringThe University of Michigan-DearbornDearbornMichiganUSA

The damage effects of water sorption on the mechanical properties of the hydroxyapatite particle reinforced Bis-GMA/TEGDMA copolymer （HA/Bis-GMA/TEGDMA） h-ave been predicted using 3D finite cell models. The plasticizer effect on the polymer matrix was considered as a variation of its Young＇s modulus. Three different cell models were used to determine the influence of varying particle contents, interphase strength and moisture concentration on the debonding damage. The stress distribution pattern has been examined and the stress transfer mode clarified. The Young＇s modulus and fracture strength of the Bis-GMA/TEGDMA composite were also predicted using the model with and without consideration of the damage. ine Iormer results with consideration of the debonding damage are in good agreement with existing literature experimental data. The shielding effect of our proposed model and an alternative approach were discussed. The Fcc cell model has also been extended to predict the critical load for the damaged and the undamaged composite subject to the 3-point flexural test.

关键词： water sorption dental composite interphase debonding finite element method (FEM) unit cell model

Refnement of the supercontinent cycle with Hf, Nd and Sr isotopes

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Geoscience Frontiers 2013年第6期4卷 667-680页

作者： Kent c.condie Richard c.Aster Department of Earth and Environmental Science New Mexico Institute of Mining and Technology Geosciences Department Colorado State University

The combined use of Hf,Nd and Sr isotopes is more useful in understanding the supercontinent cycle than the use of only Hf isotopic data from detrital *** and Nd seawater isotopes,although not as precise as εNd and εHf distributions,also record input from ocean ridge *** detrital zircons where sources cannot be precisely located because of crustal recycling,both the location and tectonic setting often can be constrained for whole-rock Nd isotopic ***,primary zircon sources may not reside on the same continent as derivative detrital zircons due to supercontinent breakup and *** to all of the isotopic studies are geographic sampling biases reflecting outcrop distributions,river system sampling,or geologists,and these may be responsible for most of the decorrelation observed between isotopic *** between 3.5 and 2 Ga based on εHf median values of four detrital zircon databases as well as our compiled εNd database are noisy but uniformly distributed in time,whereas data between 2 and 1 Ga data are more tightly clustered with smaller *** age peaks suggest that both isotopic systems are sampling similar types of *** after 1 Ga and before 3.5 Ga do we see wide variations and significant disagreement between databases,which may partially reflect variations in both the number of sample locations and the number of samples per *** and internal orogens show similar patterns in εNd and εHfwith age suggesting that both juvenile and reworked crustal components are produced in both types of orogens with similar ***,both types of orogens clearly produce more juvenile isotopic signatures in retreating mode than in advancing *** secular changes in εHf and εNd distributions correlate with the supercontinent *** supercontinent breakup is correlated with short-lived decreasing εHf and εNd （≤ 100 Myr） for most supercontinents,there is no isotopic evidence for

关键词： Supercontinent cycle Hf isotopes Nd isotopes collisional orogens Accretionary orogens

A Dimension-Reduction Interval Analysis Method for Uncertain Problems

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computer Modeling in Engineering & Sciences 2017年第3期113卷 239-259页

作者： J.c.Tang c.M.Fu State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha City410082P.R.China college of Mechanical Engineering University of South ChinaHengyang 421001P.R.China

In this paper,an efficient interval analysis method called dimension-reduction interval analysis(DRIA)method is proposed to calculate the bounds of response functions with interval variables,which provides a kind of solution method for uncertainty analysis problems of complex structures and ***,multi-dimensional function is transformed into multiple one-dimensional functions by extending dimension reduction method to the interval analysis ***,all the one-dimensional functions are transformed to standard quadratic form by second order Taylor expansion *** a result,the multi-dimensional function is approximately represented by the functions that each interval variable occurs once,and interval power arithmetic can be used to efficiently calculate the bounds of response functions in restricted ***,three numerical examples and an engineering application are investigated to demonstrate the validity of the proposed method.

关键词： Interval uncertainty interval analysis dimension-reduction method over estimation

Artificial urinary sphincter:current status and future directions

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Asian Journal of Andrology 2020年第2期22卷 154-157页

作者： culley c carson Department of Urology University of North Carolina at Chapel HillChapel HillNC 27599USA

Urge urinary incontinence(UUI)is one of the most troublesome complications of surgery of the prostate whether for malignancy or benign *** many decades,there have been attempts to reduce the morbidity of this outcome with variable *** its development in the 1970s,the artificial urinary sphincter(AUS)has been the“gold standard”for treatment of the most severe cases of *** attempts including injectable bulking agents,previous sphincter designs,and slings have been developed,but largely abandoned because of poor long-term efficacy and significant *** AUS has had several sentinel redesigns since its first introduction to reduce erosion and infection and increase *** of these changes in the basic AUS design have occurred in the past three decades,and the AUS remains the same despite newer technology and materials that could improve its function and ***,newer compressive devices and slings to reposition the bladder neck for men with mildto-moderate UUI have been developed with success in select ***,the AUS has had applied antibiotic coating to all portions except the pressure-regulating balloon(PRB)to reduce infection *** basic AUS design,however,has not *** newer electronic technology,the concept of the electronic AUS or eAUS has been proposed and several possible iterations of this eAUS have been *** the eAUS is as yet not available,its development continues and a prototype device may be available *** design options are discussed in this review.

关键词： artificial sphincter bladder sling prostate sphincter urinary incontinence

Dynamic behaviour of axially moving nanobeams based on nonlocal elasticity approach

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Acta Mechanica Sinica 2010年第5期26卷 755-765页

作者： c. W. Lim c. Li Ji-Lin Yu Department of Building and construction City Universityof Hong Kong Tat Chee Avenue KowloonHong Kong SAR China State Key Laboratory of Structural Analysis for IndustrialEquipment Dalian University of TechnologyDalian 116024 China Department of Modem Mechanics University of Scienceand Technology of China Hefei 230026 China

In this article, transverse free vibrations of axially moving nanobeams subjected to axial tension are studied based on nonlocal stress elasticity theory. A new higher-order differential equation of motion is derived from the variational principle with corresponding higher-order, non-classical boundary conditions. Two supporting conditions are investigated, i.e. simple supports and clamped supports. Effects of nonlocal nanoscale, dimensionless axial velocity, density and axial tension on natural frequencies are presented and discussed through numerical examples. It is found that these factors have great influence on the dynamic behaviour of an axially moving nanobeam. In particular, the nonlocal effect tends to induce higher vibration frequencies as compared to the results obtained from classical vibration theory. Analytical solutions for critical velocity of these nanobeams when the frequency vanishes are also derived and the influences of nonlocal nanoscale and axial tension on the critical velocity are discussed.

关键词： Axially moving nanobeams critical velocity Free vibration Natural frequency Nonlocal elasticity

On the complexity of Expansive Measures

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Acta Mathematica Sinica,English Series 2015年第9期31卷 1501-1507页

作者： c.A.MORALES Instituto de Matem'atica Universidade Federal do Rio de Janeiro

We prove that the existence of positively expansive measures for continuous maps on compact metric spaces implies the existence of e 〉 0 and a sequence of （m, e）-separated sets whose cardinalities go to infinite as m →∞. We then prove that maps exhibiting such a constant e and the positively expansive maps share some properties.

关键词： Positively expansive measure complexity compact metric space

Mimicking nature at multiple scales

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Nano Research 2022年第7期15卷 6447-6448页

作者： Helmut cölfen Physical chemistry Department of ChemistryUniversity of KonstanzUniversitätsstraße 10Box 714D-78457 KonstanzGermany

Nacre-like ceramics have received an intense focus from the structural material community because the inherently low damage resistance of ceramics,which is a fatal deficiency of ceramics as reliable load-bearing *** can be improved through nacreinspired structural designs,i.e.,the“brick-and-mortar”structure with alternating soft and hard layers on the *** technologies have been developed to produce nacre-like ceramics,including freeze casting[1],magnetically assisted slip casting[2],laminating[3]and biomimetic mineralization[4].The obtained artificial ceramics can exhibit extraordinary anti-fracture behavior without introducing a high volume fraction of ductile nonceramic components causing a drastic strength decrease of the ***.

关键词： ceramics material. ceramic

Duration distributions for different softness groups of gamma-ray bursts

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Science china(Physics,Mechanics & Astronomy) 2010年第7期53卷 1375-1382页

作者： GUPTA A.c. Aryabhatta Research Institute of Observational Sciences(ARIES) Manora PeakNainital-263129India

Gamma-ray bursts(GRBs) are divided into two classes according to their *** investigate if the softness of bursts plays a role in the conventional classification of the *** employ the BATSE(Burst and Transient Source Experiment) catalog and analyze the duration distributions of different groups of GRBs associated with distinct *** analysis reveals that the conventional classification of GRBs with the duration of bursts is influenced by the softness of the *** exists a bimodality in the duration distribution of GRBs for each group of bursts and the time position of the dip in the bimodality histogram shifts with the softness *** findings suggest that the conventional classification scheme should be modified by separating the two well-known populations in different softness groups,which would be more reasonable than doing so with a single *** to the relation between the dip position and the softness parameter,we get an empirical function that can roughly set apart the short-hard and long-soft bursts:SP =(0.100 ± 0.028) T-(0.85 0.18) 90,± where SP is the softness parameter adopted in this paper.

关键词： gamma-rays bursts:methods data analysis:methods statistical

clinical management of infertile men with nonobstructive azoospermia

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Asian Journal of Andrology 2015年第3期17卷 459-470页

作者： Sandro c Esteves ANDROFERT Center for Male Reproduction Campinas 13075-460 Brazil

The clinical management of men with nonobstructive azoospermia （NOA） seeking fertility has been a challenge for andrologists, urologists, and reproductive medicine specialists alike. This review presents a personal perspective on the clinical management of NOA, including the lessons learned over 15 years dealing with this male infertility condition. A five-consecutive-step algorithm is proposed to manage such patients. First, a differential diagnosis of azoospermia is made to confirm/establish that NOA is due to spermatogenic failure. Second, genetic testing is carried out not only to detect the males in whom NOA is caused by microdeletions of the long arm of the Y chromosome, but also to counsel the affected patients about their chances of having success in sperm retrieval. Third, it is determined whether any intervention prior to a surgical retrieval attempt may be used to increase sperm production. Fourth, the most effective and efficient retrieval method is selected to search for testicular sperm. Lastly, state-of-art laboratory techniques are applied in the handling of retrieved gametes and cultivating the embryos resulting from sperm injections. A coordinated multidisciplinary effort is key to offer the best possible chance of achieving a biological offspring to males with NOA.

关键词： intracytoplasmic sperm injection male infertility nonobstructive azoospermia pregnancy outcome sperm retrieval spermatogenic failure