8,049 research outputs found
On static and fatigue strength determination of carbon fibre/epoxy composites Part 1: experiments
No full textThis work seeks to investigate the static and fatigue properties and the failure mechanisms of T300/QY8911 carbon-fibre-reinforced composite laminates with different layups to optimize the stacking sequence effect. Three different layups have been studied, namely, [45/0(2)/–45/90(2)/–45/0/45/90]s, [45/–45/0/–45/0/45/90/45/0/–45]s and [45/0/–45/0/45/0/45/0/90/0]s. The results for static strength and fatigue residual strength under different fatigue stress amplitudes are evaluated and compared with each other. The damage and failure mechanisms of the composite laminates are discussed. It is observed that all tension–tension fatigue damage patterns of the notched laminates are similar while the tension–tension fatigue properties vary with the laminate layup. The reduction of stress concentration caused by the tension–tension fatigue damage leads to an improvement of the residual strength of the notched specimens in contrast to their static strength properties. The damage mechanics of the notched laminates under compression–compression loading are more complex than those of the tension–tension fatigue specimens; their damage patterns are influenced by the test clamping fixture, the layup, the size of specimens and the diameter of the hole. The residual strengths are lower than those of the specimens without fatigue damage. It is verified that in a high-temperature and moisture environment, there is a decrease in static compression strength. The results of this study provide an insight into fatigue damage development in composites and constitute a fundamental basis for the development of a strain-based residual strength model
Remembrance, Artistry, and Metaphor: The Seven Recluses in The Peach Blossom Fan
No full text本文初衷，乃為解讀孔尚任於《桃花扇》的書寫策略上，如何將其身為聖
人後代所欲承繼的「春秋筆法」，以隱、藏、暗、渡的方式深埋於文本之內，
使《桃花扇》不只是一部傳奇、史劇，更為其苦心孤詣所刻畫的一部「南明春
秋」。文中將具體分析七名角色—即孔尚任「自評本」所謂的七位「作者」
(亂世中歸隱辟世之人); 由其在劇中之貫串離合、行事聲容，觀察孔尚任如
何將世變、隱喻、褒貶寄寓於「小人物」的書寫態度。文章結尾，將述及「老贊
禮」一角如何成為孔尚任的夫子自道，及其於全劇首尾深埋「年月密碼」暗語的
雙重心志。This paper aims to analyze the chunqiu (springs and autumns) writing strategy
in The Peach Blossom Fan. Its author, Kong Shangren, the 64th descendent of
Confucius, intended to transmit his family tradition in writing a classic and history,
but transferred the genre as a chuanqi drama. During the Ming-Qing transition, he had
to conceal his motivation within the dramatic text to prevent being recognized as a
“Southern Ming Chunqiu”, the penalty for which would be conviction or death. The
Peach Blossom Fan is not only a dramatic text, a historical play, but also was inserted
into his Confucian critical work. In this way, this paper will analyze seven characters
in the play, who were called seven zuozhe (doers) in Kong’s self-commentary, which
means these seven people were the recluses escaped from the transition of the dynasty.
The paper will explore what they did and how they thought as the plots developed, as
well as observe how Kong used these “nobodies” to present the true model in those
times of chaos. His praise of these “nobodies” reflects the fake and self-righteous
literati and “somebodies”, which constituted the subjectivity of his chunqiu writing
strategy. In the end, this paper will discuss another character, Lao Zanli (the old master
of Ceremonies), who is the archetype of the author himself who speaks out his inner
mind and the secret codes hidden in the “date” of each scene
Evaluation of transdifferentiated mesenchymal stem cells using microfluidic patterned coculture with neuron cells
No full textPersepsi pencarum Muslim terhadap penamaan wasi di Kumpulan Wang Simpanan Pekerja
No full textPenamaan wasi menjadi topik penting dalam pengurusan harta pusaka masa kini. Wasi
adalah bertanggungjawab untuk menuntut dan mengagihkan harta kepada waris yang layak
mengikut hukum faraid. Artikel ini membincangkan sikap dan pendedahan promosi terhadap
pelaksanaan penamaan wasi dalam kalangan pencarum Kumpulan Wang Simpanan Pekerja.
Kaedah tinjauan menggunakan soal selidik sebagai instrumen kajian telah digunakan. Data
diproses dan dianalisis menggunakan perisian IBM SPSS versi 20. Kajian ini mendapati nilai
skor min bagi dimensi sikap kebaikan, sikap tanggungjawab dan sikap teknikal yang dikaji
menunjukkan tahap penerimaan pencarum antara sederhana tinggi dan tinggi. Skor min bagi
dimensi sikap kebaikan merupakan skor min yang tertinggi dibandingkan dengan dua min
dimensi yang lain iaitu 4.32 (s.p 0.54). Manakala nilai skor min bagi kedua-dua dimensi
tahap pendedahan promosi yang dikaji berada pada tahap sederhana rendah iaitu media
utama (min = 2.74, s.p = 0.96) dan media alternatif (min = 2.50, s.p = 0.88)
Implicit large-eddy simulation of the stratocumulus-topped boundary layer: A grid sensitivity study
No full textA range of implicit large-eddy simulations of the stratocumulus-topped boundary layer is performed to study the influence of grid resolution on selected parameters including liquid water path and second and third moments of vertical velocity fluctuations. The simulations are based on two sets of aircraft measurements, which are also used to evaluate the results of the simulations. The specific case presented here indicates that simulations with a grid aspect ratio accounting for the anisotropic nature of the turbulence near the surface and at the top of the boundary layer lead to better agreement with measurements than simulations with an isotropic grid
Entrainment and detrainment rates from the piv measurements at the top of laboratory analogs of stratocumulus and cumulus clouds
No full textWe analyze mixing at the top of laboratory analogs of convective clouds: stratocumulus and cumulus to investigate entrainment of environmental air into the cloud. We retrieve two components of air velocity using Particle Image Velocimetry technique. Suitable image processing allows to determine cloud–clear air interface. Using velocity differences between cloudy and clear sides of the interface we calculate entrainment / detrainment rates
Characterization of Failure and Permanent Deformation Behaviour of Asphalt Concrete
No full textAsphalt concrete is a viscoelastic material consisting of aggregates, filler and bitumen. The response of asphalt concrete is highly dependent on temperature, loading rate and confining pressure. Permanent deformation is one of the most important distresses developing during the flexible pavement service life. The total deformation which is visible at the pavement surface is the sum of the deformation that developed in each and every layer. In this thesis however attention will only be paid to permanent deformation of the asphalt layers. The main goal of this research was to investigate and better understand the permanent deformation behaviour of asphalt mixtures at 50°C which is a temperature that regularly occurs in asphalt wearing courses in the Netherlands and which therefore is applied in the Dutch standard for testing the resistance to permanent deformation of wearing courses. The thesis is divided in two parts. The first part focuses on sample preparation, testing procedures and fundamental properties of dense asphalt concrete (DAC) and porous asphalt concrete (PAC) mixtures and skeletons. In the second part the focus is on the prediction of permanent deformation. In the first part of this research special attention was paid to the following aspects: Effects of end constraints on test results Friction between the ends of the specimen and the top and bottom loading platens introduces extra confinement at the top and bottom of the specimen. In this research an extensive monotonic compressive testing program was performed on DAC and PAC mixtures under two different end contact conditions being full friction and reduced friction. “Full friction” was achieved by gluing the specimen to the top and bottom loading platens. “Reduced friction” was obtained by using a sandwich-shaped friction reduction system which consisted of two thin rubber sheets and vacuum grease in between. The results show that in the case of “full friction” the failure stress is overestimated and the displacement at failure is underestimated. The results also show that in the case of uniaxial testing without confinement and when using the friction reduction system, a deformation correction is needed to obtain the true deformation of the specimen. When confining pressure is applied deformations due to the friction reduction system can be ignored. The stress-strain behaviour of asphalt mixtures The permanent deformation behaviour of asphalt mixtures is highly dependent on temperature, stress conditions and number of load repetitions. A better understanding of the stress-strain behaviour of asphalt mixtures is beneficial for a better understanding of the permanent deformation. Therefore an extensive monotonic compressive test program was conducted on DAC and PAC at 40°C and 50°C with 3 various confining pressures and 5 different loading rates. The test results showed that the stress-strain behaviour of DAC significantly depends on temperature, strain rate and confinement. The results also showed that at high temperatures the PAC mixture behaves much alike a granular material with little cohesion. In this case the skeleton of PAC plays a significant role in the mechanical behaviour and this behaviour is highly dependent on the level of confinement. Behaviour of aggregate skeletons Permanent deformation develops at elevated temperatures. At elevated temperatures, the contribution of the aggregate skeleton becomes crucial. For this reason monotonic compressive tests were conducted on DAC and PAC skeletons at two strain rates and two confining pressure levels. The stress-strain behaviour of the DAC and PAC skeleton were compared with the stress-strain behaviour of both mixtures. The results implied that the bituminous mastic in DAC acts as a binder and contributes to the behaviour of the DAC asphalt mixture. The results also showed that the PAC aggregate skeleton shows typical elastoplastic behaviour regardless of the strain rates. In the second part of this thesis repeated load triaxial tests to study the development of permanent deformation were performed on the DAC mixture at 50°C and the following questions related to permanent deformation of the DAC mixture were discussed. Scatter observed in permanent deformation results A power function was used to model the obtained permanent deformation. A large scatter in the model parameters was observed even at the same stress ratio for selected test specimens. The possible relation between the scatter on one hand and the air voids content and resilient modulus of specimens on the other was studied. CT scanning was used to investigate the internal structure of the intact and tested specimens. The results showed that there is no clear relationship between air voids and the parameters describing the development of the permanent deformation with increasing number of load repetitions. The results also showed that the model parameters were stress dependent and a strong relationship was found between the model parameters and the resilient modulus after 1000 load repetitions. The CT scan results showed that different failure modes took place in the permanent deformation tests and that the internal structure of specimens is important for the development of permanent deformation. It is believed that part of the scatter in the test results can be explained by the variation in internal structure. Influence of loading pattern on permanent deformation The influence of different loading pulses and rest times on the permanent deformation of DAC was also investigated by performing Triaxial Repeated Load Permanent Deformation (TRLPD) test. The tests were performed at two different loading patterns, being 0.2 s load + 1.8 s rest and 0.4 s load + 0.6 s rest, and at two confinement levels of 150 kPa with a stress ratio 0.43 and 100 kPa with a stress ratio 0.3. The results showed that the stress ratio has a significant influence on the permanent deformation while the loading time has little influence on the development of permanent deformation. At the same stress level it seems that the longer loading time does not result in larger permanent deformation. Evolution of the resilient modulus in relation to the number of load repetitions In order to obtain a better understanding of the relationship between permanent strain and resilient strain which is developed in the DAC test specimens during the repeated load triaxial tests, the evolution of the resilient modulus of DAC with the number of load repetitions was investigated and modelled. The results showed that the resilient modulus of DAC reduced during the first load repetitions and tended to take a constant value after 1000 load repetitions. Evolution of Burgers’ model parameters in relation to the number of load repetitions The measured total strain was decomposed into elastic strain, delayed elastic strain and viscous permanent strain and modelled by means of the Burgers’ model. The evolution of Burgers’ model parameters obtained at two different loading patterns was investigated in this study. It was found that the value of the parameter representing the dashpot in series, used for modelling the permanent deformation, increased with increasing number of load repetitions and tended to be constant after thousands of load repetitions. This value however strongly decreased when dilation of the specimen occurred. The loading pattern had a significant influence on the value of this viscous parameter Shake down limit in permanent deformation of DAC In order to explore the existence of a shakedown limit for the tested DAC mixture, five representative permanent deformation tests were analyzed. From this analysis it appeared that below a stress ratio of 0.3 (the ratio of applied vertical stress to vertical stress at failure at the same confinement level) only a limited amount of permanent deformation developed after a large number of load repetitions. The stress ratio of 0.3 is proposed to be the shake down limit at 50°C for the test conditions and DAC mixture used in this research. Permanent deformation modeling based on Dissipated Energy Concept Most of the permanent deformation prediction models are simply relating permanent deformation to stress conditions and the number of load repetitions. In this study a permanent deformation model was developed based on dissipated energy. It was shown that the initial dissipate energy, the applied stress level and the number of load repetitions explain very well the permanent deformation development.Structure EngineeringCivil Engineering and Geoscience
Prof. S.P. Fedorov — founder of urology in Russia (150th anniversary of the birthday)
No full textThis article presents the important scientific achievements of S.P. Fedorov as a urologist. S.P. Fedorov is the author of over 120 scientific papers. It was noted that in 1892 he was the first in Russia to prepare and use cholera antitoxin for the treatment of patients, then tetanus toxin and antitoxin, found that antitoxin protects against tetanus if it is administered simultaneously with the toxin. Abroad S.P. Fedorov studied the system of aseptic mode of operation from K. Schimmelbush, and L. Casper studied the method of cystoscopy and catheterization of the ureters and other endoscopic methods that appeared at that time. It was shown that S.P. Fedorov developed new surgeries — in situ pyelotomy, subcapsular nephrectomy, and new surgical instruments were proposed. He is rightly called the father of Russian urology. The circumstance is analyzed that the main direction of S.P. Fedorov's scientific activity was the problems of surgery of the urinary and biliary tracts. He summarized the extensive experience of the surgeon in the Atlas of Cystoscopy and Rectoscopy (1911), the Surgery of the Kidneys and Ureters (1923-1925), and others. Galpernom edition of the surgical journal «New Surgical Archive», essentially the first Soviet surgical journal, created in the difficult years of the Civil War and post-war devastation. He was the editor of the 1st edition of the BME, together with S.S. Girgolavom and A.V. Martynov was the editor of the multivolume Guide to Practical Surgery. S.P. Fedorov created a major domestic surgical school, from which dozens of specialists, heads of surgical departments of medical universities in various cities of the USSR graduated. The name of S.P. Fedorov was given to the department of hospital surgery of the Military Medical Academy. S.M. Kirov. It is noted that he was the first of the Soviet surgeons to be awarded the Order of Lenin (1933)
Measurements of turbulence at stratocumulus top
No full textUsing 1m resolution airborne data from research flights we divide stratocumulus top region into sublayers and characterize properties of turbulence in each sublayer. Results indicate, that there are no clear differences of turbulence properties between thermodynamically different "calassical" and "non-classical" stratocumulus regimes, but there are clear signs of turbulence ainsotropy in stably stratified sublayers in the cloud top region
Background Subtraction Based on a Robust Consensus Method
No full textStatistical background modeling is a fundamental and important part of many visual tracking systems and of other computer vision applications. In this paper, we presents an effective and adaptive background modeling method for detecting foreground objects in both static and dynamic scenes. The proposed method computes SAmple CONsensus (SACON) of the background samples and estimates a statistical model per pixel. Numerous experiments on both indoor and outdoor video sequences show that the proposed method, compared with several state-of-the-art methods, can achieve very promising performance.Hanzi Wang and David Sute
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