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Fluid Dynamics & Materials Processing 2020年第4期16卷 801-811页

作者： Yuli D.Chashechkin Andrey Y.Ilinykh Ishlinsky Institute for Problems in Mechanics of the Russian Academy of Sciences Moscow119526Russia

The interaction of a falling drop(diluted aqueous solution of ink in various concentrations)with a target fluid(partially degassed tap water)has been tracked by means of high-resolution video recording and photography.The experimental setup has carefully been prepared in order to preserve the axial symmetry of initial conditions.Three regimes of interaction have been identified accordingly(depending on the drop velocity as controlled by the distance of fall):rapid droplet coalescence,rebound with the conservation of the drop volume and shape,and partial coalescence.Previous findings are recovered and confirmed,and enriched with heretofore unseen observations of complex partial coalescence.An extensive set of data is reported to support understanding of the observed dynamics and their repeatability and reproducibility.The overall study has been carried out with the express intent to spur the future development of detailed mathematical models and numerical methods suited for this kind of problems.

关键词： Drop coalescence Bounce spray transport of matter miscible fluids

The CST Bounce universe model——A parametric study

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Science China(Physics,Mechanics & Astronomy) 2019年第1期62卷 9-15页

作者： Yeuk-Kwan Edna Cheung Xue Song ShuYi Li YunXuan Li YiQing Zhu Department of Physics Nanjing University Institute of High Energy Physics China Academy of Sciences Department of Physics Princeton University Department of Physics Brown University California Institute of Technology ETH Zürich

A Bounce universe model with a scale-invariant and stable spectrum of primordial density perturbations was constructed using a consistent truncation of the D-brane dynamics from Type IIB string theory. A coupling was introduced between the tachyon field and the adjoint Higgs field on the D3-branes to lock the tachyon at the top of its potential hill and to model the Bounce process,which is known as the Coupled Scalar and Tachyon Bounce(CSTB) Universe. The CSTB model has been shown to be ghost free,and it fulfils the null energy condition; in addition, it can also solve the Big Bang cosmic singularity problem. In this paper we conduct an extensive follow-up study of the parameter space of the CSTB model. In particular we are interested in the parameter values that can produce a single Bounce to arrive at a radiation-dominated universe. We further establish that the CSTB universe is a viable alternative to inflation, as it can naturally produce a sufficient number of e-foldings in the locked inflation epoch and in the post-Bounce expansion to overcome the four fundamental limitations of the Big Bang cosmology, which are flatness, horizon,homogeneity and singularity, resulting in a universe of the current size.

关键词： Bounce universe Big Bang singularity tachyon inflation flatness and horizon problems

Could Gravitons from a Prior Universe Survive a (LQG Inspired) “Quantum Bounce” to Re-Appear in Our Present Universe?

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Journal of High Energy Physics, Gravitation and Cosmology 2017年第4期3卷 624-634页

作者： Andrew Walcott Beckwith Physics Department Chongqing University College of Physics Chongqing University Huxi Campus Chongqing China

We ask the question if a formula for entropy, as given by with a usual value ascribed of initial entropy of the onset of inflation can allow an order of magnitude resolution of the question of if there could be a survival of a graviton from a prior to the present universe, using typical Planckian peak temperature values of . We obtain values consistent with up to 1038 gravitons contributing to an energy value of if we assume a relic energy contribution based upon each graviton initially exhibiting a frequency spike of 1010 Hz. The value of is picked from looking at the aftermath of what happens if there exists a quantum Bounce with a peak density value of [1] in a regime of LQG Bounce regime radii of the order of magnitude of meters. The author, in making estimates specifically avoids using ,?by setting the chemical potential for ultra high temperatures for reasons which will be brought up in the conclusion.

关键词： Gravitons Prior Universe Quantum Bounce

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Matter Bounce宇宙模型研究

山西大同大学学报（自然科学版） 2013年第3期29卷 23-24,27页

作者：王晓明山西大同大学物理与电子科学学院山西大同037009

通过描述宇宙学的发展历史和现状,指出大爆炸理论和暴涨理论虽然有许多优点,可以解释许多现象,但它们并不是完美无缺,无懈可击,仍然有一些无法解释的问题。而matter Bounce宇宙模型是一个可以取代前两种理论的模型,可以得到与宇宙观测... 详细信息

通过描述宇宙学的发展历史和现状,指出大爆炸理论和暴涨理论虽然有许多优点,可以解释许多现象,但它们并不是完美无缺,无懈可击,仍然有一些无法解释的问题。而matter Bounce宇宙模型是一个可以取代前两种理论的模型,可以得到与宇宙观测相吻合的结论,因此研究这个模型是非常有意义的。

关键词：宇宙学宇宙暴涨 matter Bounce

Cosmology with Bounce by Flat Space-Time Theory of Gravitation and a New Interpretation

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Journal of Modern Physics 2013年第7期4卷 20-25页

作者： Walter Petry Mathematisches Institut der Universitaet Duesseldorf Duesseldorf Germany

General relativity predicts a singularity in the beginning of the universe being called big bang. Recent developments in loop quantum cosmology avoid the singularity and the big bang is replaced by a big Bounce. A classical theory of gravitation in flat space-time also avoids the singularity under natural conditions on the density parameters. The universe contracts to a positive minimum and then it expands during all times. It is not symmetric with regard to its minimum implying a finite age measured with proper time of the universe. The space of the universe is flat and the total energy is conserved. Under the assumption that the sum of the density parameters is a little bit bigger than one the universe is very hot in early times. Later on, the cosmological model agrees with the one of general relativity. A new interpretation of a non-expanding universe may be given by virtue of flat space-time theory of gravitation.

关键词： Gravitation Cosmology Big Bounce Flat Space No Big Bang Non-Expanding Universe

Modified Ceiling Bounce Model for Computing Path Loss and Delay Spread in Indoor Optical Wireless Systems

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International Journal of Communications, Network and System Sciences 2009年第8期2卷 754-758页

作者： K. SMITHA A. SIVABALAN J. JOHN 不详

This paper proposes modifications to the tradional Ceiling Bounce Model and uses it to characterize diffuse indoor optical wireless channel by analyzing the effect of transceiver position on signal propagation properties. The modified approach uses a combination of the tradional ceiling Bounce method and a statistical approach. The effects of different transmitter-receiver separations and height of the ceiling on path loss and delay spread are studied in detail.

关键词： Indoor Optical Channel Modified Ceiling Bounce Model Path Loss Delay Spread

Drop impact dynamic and directional transport on dragonfly wing surface

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Friction 2023年第5期11卷 737-747页

作者： Jing XU Wenjun LIU Weixiao SHANG Jun CHEN Jiadi LIAN School of Mechanical Engineering Hangzhou Dianzi UniversityHangzhou 310018China School of Mechanical Engineering Purdue UniversityWest LafayetteIndiana 47907USA College of Mechanical and Electrical Engineering China Jiliang UniversityHangzhou 310018China

The ability of dragonflies to fly in the rain without being wetted by raindrops has motivated researchers to investigate the impact behavior of a drop on the superhydrophobic wings of dragonflies.This superhydrophobic surface is used as a reference for the design of directional surfaces and has attracted extensive attention owing to its wide applicability in microfluidics,self-cleaning,and other fields.In this study,the static contact angle and rebound process of a drop impacting a dragonfly wing surface are investigated experimentally,whereas the wetting pressure,Gibbs free energy,and Stokes number vs.coefficient of restitution are theoretically calculated to examine the dynamic and unidirectional transport behaviors of the drop.Results show that the initial inclination angle of the dragonfly wing is similar to the sliding angles along with the drop sliding.The water drop Bounces from the bottom of the dragonfly wing to the distal position,demonstrating directional migration.The drop impacts the dragonfly wing surface,and the drop exhibits compression,recovery,and separation phases;in these three phases,the drop morphology evolves.As the Gibbs free energy and cross-sectional area evolve,the coefficient of restitution decreases as the drop continues to Bounce,and the Stokes number increases.

关键词： dragonfly wing superhydrophobic wettability directional transport Bounce

转变学习方式的有效教学实践——以《数据收集和处理——声音传播问题和Bounce实验》为例

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科技致富向导 2009年第18期 121-122页

作者：胡燕菁上海市曹杨二中

杨振宁谈中美教育的差异时指出:'中国学生在学习中习惯于接受,而不习惯于思考,更不习惯于怀疑。'确实传统的数学教学强调知识或技能的传递,强调教师对教学的控制,教师是知识的灌输者和课堂的控制者。正是因为这样的角色定位,使得课堂教... 详细信息

杨振宁谈中美教育的差异时指出:'中国学生在学习中习惯于接受,而不习惯于思考,更不习惯于怀疑。'确实传统的数学教学强调知识或技能的传递,强调教师对教学的控制,教师是知识的灌输者和课堂的控制者。正是因为这样的角色定位,使得课堂教学中缺乏创新意识和创

关键词：数据收集声音传播 Bounce 转变学习方式学生学习方式教学实践

Exploration of petrographic,elemental,and material properties of dynamic failure-prone coals

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International Journal of Mining Science and Technology 2020年第1期30卷 69-75页

作者： Heather Lawson Spokane Mining Research Division National Institute for Occupational Safety and HealthSpokaneWA 99207USA

The purpose of this study is to explore how the geochemical and petrographic components of coal may impact its physical properties and how these correlate with a history of reportable dynamic failure in coal mines.Dynamic failure events,also termed bumps,Bounces,or bursts,are the explosive failures of rock in a mining environment.These events occur suddenly and often with no warning,resulting in worker injury up to and including fatality in greater than 60%of reportable cases through the Mine Safety and Health Administration(MSHA).A database of variables was compiled using publicly available datasets,which includes compositional geographic,strength,and Hardgrove grindability index(HGI)data.Results indicated that bumping coals were less mature,lower in carbon,higher in oxygen,softer,and less well cleated than coals that did not bump.High liptinite content was found to correlate with higher average uniaxial compressive strength(UCS)values.However,no clear and direct correlation between UCS and dynamic failure status was observed.The findings of this study established that differences existed between coals that had versus had not experienced reportable dynamic failure accidents.These differences were inherent to the coal itself and were independent of mining-induced risk factors.Results further illuminated how compositional attribute of coal influenced physical properties and began to clarify potential links between geochemistry and dynamic failure status.Only through the better understanding of risk can more effective mitigating strategies be enacted.

关键词： Dynamic failure Coal Bump Bounce Burst

Generic phase portrait analysis of finite-time singularities and generalized Teleparallel gravity

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Chinese Physics C 2017年第12期41卷 133-154页

作者： W. El Hanafy G.G.L. Nashed Centre for Theoretical Physics The British University in Egypt P.O. Box 43 El Sherouk City Cairo 11837 Egypt Mathematics Department Faculty of Science Ain Shams University Cairo 11566 Egypt Egyptian Relativity Group (ERG) Cairo University Giza 12613 Egypt

We analyze the four common types of finite-time singularity using a generic framework of the phase portrait geometric approach. This technique requires the Friedmann system to be written as a one-dimensional autonomous system. We employ a scale factor that has been used widely in the literature to realize the four finite- time singularity types, then we give a detailed discussion for each case showing possible novel models. Moreover, we show how different singularity types can play essential roles in different cosmological scenarios. Among several modified gravity theories, we show that the f（T） cosmology is compatible with the phase portrait analysis, since the field equations include Hubble derivatives only up to first order. Therefore, we reconstruct the f（T） theory which generates these phase portraits. We also perform a complementary analysis using the effective equation of state. Furthermore, we investigate the role of the torsion fluid in realizing the cosmic singularities.

关键词： inflation Bounce big brake ACDM teleparallel gravity