GEOMETRY INDUCED DELAYS OF SLIME MOULD PROPAGATION

2013 ◽  
Vol 08 (01n02) ◽  
pp. 89-97
Author(s):  
ANDREW ADAMATZKY
Keyword(s):  
Finite Size ◽  
Underlying Mechanism ◽  
Narrow Channel ◽  
Laboratory Studies ◽  
Nonlinear Media ◽  
Narrow Channels ◽  
Slime Mould ◽  
Binary State ◽  
Experimental Laboratory ◽  
Geometrically Constrained

Slime mould Physarum polycephalum propagates on nutrient substrates similarly to auto-waves in nonlinear media. In experimental laboratory studies we uncover that the width of geometrically constrained substrate affects the speed of Physarum propagation. We show that Physarum slows down when the width of the substrate increases. The slime mould propagates quicker from the vertex of a triangle to its base than from the base to the vertex. Physarum grows quicker in narrow channels than in wider channels. One can also slow down Physarum propagation by making a finite size expansion of the otherwise narrow channel. In computational experiments with a binary state cellular automaton model we demonstrate that a limitation on the slime mould's body mass production rate could be an underlying mechanism for the width-dependent slowdown of Physarum propagation.

Development of Advanced High Heat Flux Cooling System for Power Electronics

2009 ◽  
Author(s):  
Yasuhisa Shinmoto ◽  
Shinichi Miura ◽  
Koichi Suzuki ◽  
Yoshiyuki Abe ◽  
Haruhiko Ohta
Keyword(s):  
Heat Flux ◽  
Power Electronics ◽  
Critical Heat Flux ◽  
Heating Surface ◽  
Narrow Channel ◽  
High Heat ◽  
High Heat Flux ◽  
Gap Size ◽  
Narrow Channels ◽  
Very High

Recent development in electronic devices with increased heat dissipation requires severe cooling conditions and an efficient method for heat removal is needed for the cooling under high heat flux conditions. Most researches are concentrated on small semiconductors with high heat flux density, while almost no existing researches concerning the cooling of a large semiconductor, i.e. power electronics, with high heat generation density from a large cooling area. A narrow channel between parallel plates is one of ideal structures for the application of boiling phenomena which uses the cooling for such large semiconductors. To develop high-performance cooling systems for power electronics, experiments on increase in critical heat flux (CHF) for flow boiling in narrow channels by improved liquid supply was conducted. To realize the cooling of large areas at extremely high heat flux under the conditions for a minimum gap size and a minimum flow rate of liquid supplied, the structure with auxiliary liquid supply was devised to prevent the extension of dry-patches underneath flattened bubbles generated in a narrow channel. The heating surface was experimented in two channels with different dimensions. The heating surfaces have the width of 30mm and the lengths of 50mm and 150mm in the flow direction. A large width of actual power electronics is realizable by the parallel installation of the same channel structure in the transverse direction. The cooling liquid is additionally supplied via sintered metal plates from the auxiliary unheated channels located at sides or behind the main heated channel. To supply the liquid to the entire heating surface, fine grooves are machined on the heating surface for enhance the spontaneous liquid supply by the aid of capillary force. The gap size of narrow channels are varied as 0.7mm, 2mm and 5mm. Distribution of liquid flow rate to the main heated channel and the auxiliary unheated channels were varied to investigate its effect on the critical heat flux. Test liquids employed are R113, FC72 and water. The systematic experiments by using water as a test liquid were conducted. Critical heat flux values larger than 2×106W/m2 were obtained at both gap sizes of 2mm and 5mm for a heated length of 150mm. A very high heat transfer coefficient as much as 1×105W/m2K was obtained at very high heat flux near CHF for the gap size of 2mm. This paper is a summary of experimental results obtained in the past by the present authors.

Visualization of Boiling in Inclined Rectangular Narrow Long Channels

2006 ◽  
Author(s):  
Sang W. Noh ◽  
Jae S. Yoo ◽  
Kune Y. Suh
Keyword(s):  
Inclination Angle ◽  
Atmospheric Pressure ◽  
Narrow Channel ◽  
Vertical Position ◽  
Bubble Behavior ◽  
Water Pool ◽  
Narrow Channels ◽  
Saturated Water ◽  
Test Parameters ◽  
Reactor Pressure

During the Three-Mile Island Unit 2 (TMI-2) accident, the lower part of the reactor pressure vessel had been overheated and then rather rapidly cooled down, as it was later found out in a vessel investigation project. These findings triggered a great deal of investigations to determine the critical heat flux (CHF) in narrow channels. Experiments were conducted to determine the CHF on a long downward heated rectangular narrow channel by changing the orientation of a copper crevice (5×105 mm2) type heater assembly. The test heater was placed in a demineralized, saturated water pool at atmospheric pressure. This work aims also to investigate the general boiling phenomena and the triggering mechanism for the CHF in the narrow channel through visualization of the bubble behavior in the vicinity of CHF. The test parameters include the channel size of 5 mm and the surface orientation angles from the downward facing position (180°) to the vertical position (90°). It was found that the CHF decreases as the surface inclination angle increases and as the gap size decreases. It was also shown that there exists a transition angle at which the CHF changes with a rapid slope, and that the inclination angle affects the bubble layer and the bubble discharge from the narrow gap.

scholarly journals Finite-size transitions in complex membranes

2020 ◽  
Author(s):  
M. Girard ◽  
T. Bereau
Keyword(s):  
Experimental Evidence ◽  
Critical Point ◽  
Finite Size ◽  
Underlying Mechanism ◽  
Large Temperature ◽  
Strong Argument ◽  
Biological Regulation ◽  
Critical Manifold ◽  
Critical Composition ◽  
Dynamics Simulations

ABSTRACTThe lipid raft hypothesis postulates that cell membranes possess some degree of lateral organization. The last decade has seen a large amount of experimental evidence for rafts. Yet, the underlying mechanism remains elusive. One hypothesis that supports rafts relies on the membrane to lie near a critical point. While supported by experimental evidence, the role of regulation is unclear. Using both a lattice model and molecular dynamics simulations, we show that lipid regulation of a many-component membrane can lead to critical behavior over a large temperature range. Across this range, the membrane displays a critical composition due to finite-size effects. This mechanism provides a rationale as to how cells tune their composition without the need for specific sensing mechanisms. It is robust and reproduces important experimentally verified biological trends: membrane-demixing temperature closely follows cell growth temperature, and the composition evolves along a critical manifold. The simplicity of the mechanism provides a strong argument in favor of the critical membrane hypothesis.SIGNIFICANCEWe show that biological regulation of a large amount of phospholipids in membranes naturally leads to a critical composition for finite-size systems. This suggests that regulating a system near a critical point is trivial for cells. These effects vanish logarithmically and therefore can be present in micron-sized systems.

Study of Flow-Induced Vibrations of a Plate in Narrow Channels

1967 ◽  
Vol 89 (4) ◽  
pp. 824-830 ◽  
Author(s):  
S. R. Bland ◽  
R. H. Rhyne ◽  
H. B. Pierce
Keyword(s):  
Rocket Engine ◽  
Strong Dependence ◽  
Narrow Channel ◽  
Two Dimensional ◽  
Rigid Plate ◽  
Narrow Channels ◽  
The Core ◽  
Flow Induced Vibrations ◽  
Nuclear Rocket ◽  
Time Of Failure

Vibration phenomena associated with narrow channel flow have come under study as a result of the core failure of an early nuclear rocket engine. Since the mechanism of this vibration instability was not well understood at the time of failure, an investigation of a simple system consisting of a rigid plate with two degrees of spring-restrained freedom in a two-dimensional channel has been made both experimentally and analytically. The results show a strong dependence of the flow rate required for plate oscillation on the channel width (normal to plate).

scholarly journals Recent Laboratory Photochemical Studies and Their Relationship to the Photochemical Formation of Cometary Radicals

1989 ◽  
Vol 116 (1) ◽  
pp. 313-332
Author(s):  
William M. Jackson
Keyword(s):  
Laboratory Studies ◽  
Laboratory Evidence ◽  
Photochemical Formation ◽  
Laboratory Techniques ◽  
Unstable Molecules ◽  
Experimental Laboratory ◽  
Recent Laboratory

AbstractExperimental laboratory techniques used in studying the photochemistry of stable and unstable molecules are discussed. The laboratory evidence for the photochemical formation of C2 from C2H, C3 from C3H2, and NH from NH2 is presented. Other recent results obtained in laboratory studies of H2O, H2S, NH3, and HCN are reported.

Heat Transfer and Bubble Movement of Double- and Single-Side Heating Subcooled Flow Boiling in Narrow Channels

2005 ◽  
Author(s):  
Liang-Ming Pan ◽  
Chuan He ◽  
Ming-Dao Xin ◽  
Tien-Chien Jen ◽  
Qinghua Chen
Keyword(s):  
Heat Transfer ◽  
Flow Boiling ◽  
Narrow Channel ◽  
Nucleate Boiling ◽  
Bubble Behavior ◽  
Subcooled Flow Boiling ◽  
Narrow Channels ◽  
Subcooled Flow ◽  
Single Side ◽  
Micro Channels

Compared with conventional channels, narrow and micro channels have significant heat transfer enhancement characteristic. With smooth internal surface, such channels can efficiently avoid encrustation at the washing of the high-speed liquid. Moreover, heat transfer elements can be easily assembled. These types of channels have been adopted extensively in many engineering applications, e.g. microelectronic cooling, advanced nuclear reactor, cryogenic, aviation and space technology and thermal engineering. Geometrical size of flow passage-away affects heat exchange of flow boiling, with the result that the bubble in narrow channel acts very different from those in non-narrow channel. This paper experimentally compared the bubble behavior with different heating methods of narrow rectangular channels, and the bubble behavior of subcooled flow boiling of R-12 in the narrow channels both with double side and single heating. Experimental settings are: the heating length of test-section is 400 mm, the cross-section is 35 mm in width and 2mm in gap size, mass flux is 700∼1500 kg.m−2.s−1, the heat flux is 25∼70kW.m−2 and the pressure is 1.3∼2.0 MPa. Comparisons were made on Onset of Nucleate Boiling (ONB) point and bubble characters with various flow patterns. Results revealed that the characteristics of double and single side heating shown good agreement with proper modifications.

scholarly journals Fungal Sensing Skin

2020 ◽  
Author(s):  
Andrew Adamatzky ◽  
Antoni Gandia ◽  
Alessandro Chiolerio
Keyword(s):  
Laboratory Studies ◽  
Optical Stimulation ◽  
Sensing Skin ◽  
Experimental Laboratory ◽  
External Stimuli ◽  
And Robotics

Abstract BackgroundA fungal skin is a thin exible sheet of a living homogeneous mycelium made by a lamentous fungus. The skin could be used in future living architectures of adaptive buildings and as a sensing living skin for soft self-growing/adaptive robots.ResultsIn experimental laboratory studies we demonstrate that the fungal skin is capable for recognising mechanical and optical stimulation. The skin reacts dierently to loading of a weight, removal of the weight, and switching illumination on and off.ConclusionsThese are the rst experimental evidences that fungal materials can be used not only as mechanical `skeletons' in architecture and robotics but also as intelligent skins capable for recognition of external stimuli and sensorial fusion.

Choosing the chemicals and advanced filter media for enhancing the process of mine water purification

2021 ◽  
pp. 60-64
Author(s):  
В.Ю. Касперович
Keyword(s):  
Heavy Metals ◽  
Mine Water ◽  
Suspended Solids ◽  
Laboratory Studies ◽  
Mine Waters ◽  
Coagulation And Flocculation ◽  
Experimental Laboratory ◽  
Treatment Facilities ◽  
Surface Water Bodies ◽  
Sorption Media

В настоящее время строительство сооружений для очистки шахтных вод является одним из важных мероприятий, направленных на сохранение поверхностных водотоков и водоемов. Количество сбрасываемых шахтных вод в поверхностные водоемы может быть сокращено в результате их использования для комплексного обеспыливания в шахтах, технического водоснабжения и других наиболее водоемких технологических процессов. Одним из эффективных способов очистки шахтных вод от взвешенных веществ и тяжелых металлов является реагентная обработка высокомолекулярными флокулянтами, использование которых позволяет уменьшить расход неорганических коагулянтов и интенсифицировать процесс осаждения взвешенных веществ и тяжелых металлов. Предварительная обработка шахтной воды перед контактными осветлителями позволяет значительно увеличить пропускную способность действующих очистных сооружений, стабилизировать их работу при колебании качественного состава и температуры шахтной воды, снизить нагрузку на последующие стадии очистки на скорых фильтрах. Представлены результаты экспериментальных лабораторных исследований пробной коагуляции и флокуляции с последующим фильтрованием на скорых фильтрах с применением каталитической фильтрующей загрузки Orefilter В, сорбента АС и сорбционной загрузки Extrasorb, а также удаления (отдувки) аммиака из шахтной воды. Currently, the construction of facilities for the purification of mine waters is one of the important measures aimed at preserving surface watercourses and water reservoirs. The amount of mine water discharged into surface water bodies can be reduced by reusing it for complex dedusting in mines, process water supply and other most water-intensive technological processes. One of the effective ways of removing suspended solids and heavy metals from mine water is chemical treatment with high-molecular flocculants that provide for reducing the consumption of inorganic coagulants and enhancing the process of suspended solids and heavy metals precipitation. Pretreatment of mine water upstream contact clarifiers can significantly increase the capacity of existing treatment facilities, stabilize their operation in case of fluctuations in the quality composition and temperature of mine water, and reduce the load on the subsequent stages of filtration in rapid filters. The results of experimental laboratory studies of trial coagulation and flocculation with subsequent filtration in rapid filters using Orefilter B catalytic filtering media, AS sorbent and Extrasorb sorption media, as well as removing (stripping) ammonia from mine water are presented.

Transport and efficiency of Brownian particles in confined narrow channels with a periodic driving force

2015 ◽  
Vol 29 (05) ◽  
pp. 1550026 ◽  
Author(s):  
Rang Wang ◽  
Jia-Ning Zhou ◽  
Xue-Mei Liu ◽  
Hua Xiao
Keyword(s):  
External Force ◽  
Driving Force ◽  
Average Velocity ◽  
Static Load ◽  
Narrow Channel ◽  
Load Force ◽  
Narrow Channels ◽  
Brownian Particles ◽  
Peaked Function ◽  
External Driving

Transport and efficiency of over-damped Brownian particles moving in a confined narrow channel is investigated in the presence of an oscillating force and a static load force. It is found that the average velocity increases monotonously with the unbiased external driving force, while the efficiency can be a peaked function of unbiased external force, which indicates that the unbiased external force can facilitate the efficiency of energy transformation. Moreover, the average velocity and the efficiency demonstrate complex behaviors due to the consideration of Stokes efficiency.

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