Synchronization Transition of Identical Phase Oscillators in a Directed Small-World Network

We numerically study a directed small-world network consisting of attractively coupled, identical phase oscillators. While complete synchronization is always stable, it is not always reachable from random initial conditions. Depending on the shortcut density and on the asymmetry of the phase coupling function, there exists a regime of persistent chaotic dynamics. By increasing the density of shortcuts or decreasing the asymmetry of the phase coupling function, we observe a discontinuous transition in the ability of the system to synchronize. Using a control technique, we identify the bifurcation scenario of the order parameter. We also discuss the relation between dynamics and topology and remark on the similarity of the synchronization transition to directed percolation.Comment: This article has been accepted in AIP, Chaos. After it is published, it will be found at http://chaos.aip.org/, 12 pages, 9 figures, 1 tabl

Torus graphs and simplicial posets

For several important classes of manifolds acted on by the torus, the information about the action can be encoded combinatorially by a regular n-valent graph with vector labels on its edges, which we refer to as the torus graph. By analogy with the GKM-graphs, we introduce the notion of equivariant cohomology of a torus graph, and show that it is isomorphic to the face ring of the associated simplicial poset. This extends a series of previous results on the equivariant cohomology of torus manifolds. As a primary combinatorial application, we show that a simplicial poset is Cohen-Macaulay if its face ring is Cohen-Macaulay. This completes the algebraic characterisation of Cohen-Macaulay posets initiated by Stanley. We also study blow-ups of torus graphs and manifolds from both the algebraic and the topological points of view.Comment: 26 pages, LaTeX2e; examples added, some proofs expande

Film condensation heat transfer of low integral-fin tube.

PhDFor condensation on horizontal low-finned tubes, the dependence of heat-transfer performance on fin spacing has been investigated experimentally for condensation of refrigerant 113 and ethylene glycol. Fourteen tubes have been used with inside diameter 9.78 mm and working length exposed to vapour 102 mm. The tube had rectangular section fins having the same width and height (0.5 mm and 1.59 mm) and with the spacing between fins varying from 0.25 mm to 20 mm. The diameter of the tube at the fin root was 12.7 mm. Tests were also made using a plain tube having the same inside diameter and an outside diameter equal to that at the root of the fins for the finned tubes. All tests were made at near atmospheric pressure with vapour flowing vertically downward with velocities of 0.24 m/s and 0.36 m/s for refrigerant 113 and ethylene glycol respectively. Optimum fin spacings were found at 0.5 mm and 1.0 mm for refrigerant 113 and ethylene glycol respectively. In earlier experiments for steam using the same tubes, the optimum fin spacing was found to be 1.5 mm. Maximum enhancement ratios of vapour-side heat-transfer coefficient (vapour-side coefficient for a finned tube / vapour-side coefficient for a plain tube. for the same vapour-side temperature difference) were 7.5, 5.2 and 3.0 for refrigerant 113, ethylene glycol and steam respectively. Enhancement phenomena have also been studied theoretically. Consideration has been given to a role of surface tension forces on the motion and configuration of condensate film. On the basis of this study, several semi-empirical equations, to predict heat-transfer performance, have been obtained. These are considered to represent recent reliable data (present and other recent works) satisfactorily

Movement of Calcuium (45Ca) to Fruit from Peduncle of Tomato Plants

Movement of calcium (45Ca) from the peduncle to fruit of tomato during the days and night was investigated. Further, the effects of additional NaCl to the culture solution on the water potential in plants and 45Ca movement to fruit were also examined. The activity of 45Ca on a dry weight basis in the peduncle was higher during the day than at night, however, in calyx and fruit the 45Ca activity was similar both during the day and night. Import of 45Ca into the leaves from the peduncle was not different between the day and the night. Additional NaCl to the culture solution resulted in a greater water saturation deficit (WSD) of the immature leaves just below the 2nd and 3rd trusses, unlike with the mature leaves below the 1st truss where the WSD did not decrease with NaCl treatment. On the oher hand, the activity of 45Ca in the peduncle and calyx was not different between the NaCl treatment and the control. However, the activity in the distal part of the fruits was lower with, NaCl treament than in the control. These results suggested that the high WSD effectively decreased the import of calcium into fruits from the peduncle. It seems that the import of 45Ca into fruit not only dependent on the conductive tissues but also a possible driving force in xylem water flow, and that NaCl interferes with movement of calcium in the fruits.トマト果柄に木綿糸を通してカルシウム(45Ca)を処理し昼夜間別に果房各部位への45Caの移行、ならびに、培養液にNaClを添加した場合の樹体内の水分状態と果実への45Ca移行について調査した。昼夜間における単位乾物重当りの45Caの非活性は果柄で昼間に有意に高くなったが、がく・果実では昼夜間差は生じなかった。また、葉でも昼夜間差はなく昼夜同程度に45Caの移行が認められた。培養液にNaClを添加しても、第1果房直下葉(成熟葉)の水分欠差が生じなかったが、第2･3段果房直下葉(未成熟葉)ではNaCl添加のよって水分欠差は有意に増大し、果柄・がくの45Ca非活性も高くなる傾向を示した。しかし果実末端部の45Ca非活性は有意に低くなり、同時に、果実全体に占める果実末端部での45Ca非活性もNaCl添加によって減少した。本試験の結果から、木綿糸処理液の果柄内への流入は樹体の水分欠差に影響を受けると考えられた。果柄内に流入した45Caは、水の流れだけでなく他の要因によっても各部位に移行するものと思われた。また、培養液へのNaCl添加により、果実末端部へのカルシウム移行がより強く抑制されるのは、果実内でのカチオン移動に競合が生じるからではないかと推察された

Micropillar compression of anisotropic Al2O3-based eutectic composite

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Orientation-dependent plastic deformability in micropillar compression of oxide ceramics

Micromechanical testing, such as nanoindentation and micropillar compression, can be the promising tool for characterizing the plastic deformability of ceramics even at temperatures below macroscopic ductile-to-brittle transitions [1,2]. Such plasticity is possibly achieved by the fracture strength increase at small scales. The fracture strength, C , is conventionally determined as a function of a crack dimension: Please click Download on the upper right corner to see the full abstract

Feasibility Investigation of Obstacle-Avoiding Sensors Unit without Image Processing

Feasibility of a simple method to detect step height, slope angle, and trench width using four infrared-light-source PSD range sensors is examined, and the reproducibility and accuracy of characteristic parameter detection are also examined. Detection error of upward slope angle is within 2.5 degrees, while it is shown that the detection error of downward slope angle exceeding 20 degrees is very large. In order to reduce such errors, a method to improve range-voltage performance of a range sensor is proposed, and its availability is demonstrated. We also show that increase in trial frequency is a better way, although so as not to increase the detection delay. Step height is identified with an error of ±1.5 mm. It is shown that trench width cannot be reliably measured at this time. It is suggested that an additional method is needed if we have to advance the field of obstacle detection

Local mechanical response in the vicinity of single grain boundary in YSZ measured by nanoindentation

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