9,371 research outputs found
Jlc R&d Status
[[abstract]]In this paper, we summarise the status of the R & D efforts for the JLC (Japan e+e- Linear Collider) project including X-band main linacs and the ATF (Accelerator Test Facility). The main emphasis is on X-band PPM klystron development, and on recent progress at ATF on studies of production of a low emittance beam and a multi-bunch beam[[fileno]]2030204030002[[department]]資訊工程學
Efficient fault-tolerant routing in multihop optical WDM networks
This paper addresses the problem of efficient routing in unreliable multihop optical networks supported by Wavelength Division Multiplexing (WDM). We first define a new cost model for routing in (optical) WDM networks that is more general than the existing models. Our model takes into consideration not only the cost of wavelength access and conversion but also the delay for queuing signals arriving at different input channels that share the same output channel at the same node. We then propose a set of efficient algorithms in a reliable WDM network on the new cost model for each of the three most important communication patterns - multiple point-to-point routing, multicast, and multiple multicast. Finally, we show how to obtain a set of efficient algorithms in an unreliable WDM network with up to f faulty optical channels and wavelength conversion gates. Our strategy is to first enhance the physical paths constructed by the algorithms for reliable networks to ensure success of fault-tolerant routing, and then to route among the enhanced paths to establish a set of fault-free physical routes to complete the corresponding routing request for each of the communication patterns.published_or_final_versio
Efficient parallel algorithms for a class of graph theoretic problems
The authors present efficient parallel algorithms for the following graph problems: finding the lowest common ancestors for vertex pairs of a directed tree; finding all fundamental cycles, a directed spanning forest, all bridges, all bridge-connected components, all separation vertices, all biconnected components, and testing the biconnectivity of an undirected graph. All these algorithms achieve the O(lg**2n) time bound.published_or_final_versio
Coupled valence and spin state transition in (Pr0.7Sm0.3)0.7Ca0.3CoO3
The coupled valence and spin state transition (VSST) taking place in
(Pr0.7Sm0.3)0.7Ca0.3CoO3 was investigated by soft x-ray absorption spectroscopy
(XAS) experiments carried out at the Pr-M4,5, Co-L2,3, and O-1s edges. This
VSST is found to be composed of a sharp Pr/Co valence and Co spin state
transition centered at T*=89.3 K, followed by a smoother Co spin-state
evolution at higher temperatures. At T < T*, we found that the praseodymium
displays a mixed valence Pr3+/Pr4+ with about 0.13 Pr4+/f.u., while all the
Co3+ is in the low-spin (LS) state. At T around T*, the sharp valence
transition converts all the Pr4+ to Pr3+ with a corresponding Co3+ to Co4+
compensation. This is accompanied by an equally sharp spin state transition of
the Co3+ from the low to an incoherent mixture of low and high spin (HS)
states. An involvement of the intermediate spin (IS) state can be discarded for
the Co3+. While above T* and at high temperatures the system shares rather
similar properties as Sr-doped LaCoO3, at low temperatures it behaves much more
like EuCoO3 with its highly stable LS configuration for the Co3+. Apparently,
the mechanism responsible for the formation of Pr4+ at low temperatures also
helps to stabilize the Co3+ in the LS configuration despite the presence of
Co4+ ions. We also found out that that the Co4+ is in an IS state over the
entire temperature range investigated in this study (10-290 K). The presence of
Co3+ HS and Co4+ IS at elevated temperatures facilitates the conductivity of
the material.Comment: 19 pages, 7 figures, Accepted in PR
Analytical and experimental study of stratification and liquid-ullage coupling, 1 June 1964 - 31 May 1965
Closed-form solution for stratification of subcooled fluids in containers subjected to heating, and for liquid-ullage vapor couplin
Cryopreservation of Coffea liberica Seeds and Embryos following desiccation and freezing treatments
Desiccation of Coffea liberica seeds for 6 days in an air-conditioned room reduced seed and attached emltryo
moisture from 52.58% and 47.49% to 14.58% and 12.56% respectively. Seed germination and viability of
the attached emltryo were maintained at moderate levels of 66% and 38% respectively. However, none of the
desiccated seeds or embryos survived freezing in liquid nitrogen. Excised emltryos desiccated in the lamina flow
cabinet lost their moisture very rapidly from 36.8% to 9.27% within 1.5 hours. More than 70% of these emltryos
survived the desiccation. Moreover, partially desiccated emltryos at 17.17% moisture or less survived subfreezing
temperatures. Between 35% to 50% survived slow freezing to -3ffC, but this was reduced to approximately 30%
when they were subsequently plunged into liquid nitrogen. Fast freezing by direct plunge into liquid nitrogen also
resulted in 10% to 35% survival. Desiccation ofexcised coffee embryos for 0.5h to 17.17% moisture was optimal
for eryopreservation, irrespective of the speed offreezing. Differential thermal analyses of seed tissues suggest that
the absence of freezable water is an important factor for successful eryopreservation of excised coffee emltryos.
However, the importance of initial vigour, moisture variation and recovery media is also discussed
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