Distributed Data Layout, Scheduling and Playout Control in a Large Scale Multimedia Storage Server

this paper, we will consider only a retrieval environment and primarily focus on the strong interaction between the architecture, data layout, data compression, and scheduling. In particular, we will present distributed multilevel data layout, scheduling and playout control schemes developed in conjunction with our architecture. These schemes allow all clients to access the same data without data replication and support both buffered as well as bufferless clients. Also, they provide strict Large Scale Multimedia Servers 2 deterministic guarantees to each active client during normal playout as well as a full spectrum of interactive stream control operations (namely, fast forward, rewind, frame advance, slow play, slow rewind, pause, stop-and-return and stop). Our implementation of the stream control operations requires no extra bandwidth reservation and provides acceptable operation latency of a few hundread milliseconds. The rest of this paper is organized as follows: Various service models that are possible for a ondemand multimedia server are illustrated in Section 2. The basics of our prototype implementation of a large scale server are presented in Section 3. Section 4 describes the distributed and hierarchical data layout scheme. Next, our basic multilevel scheduling scheme is illustrated in Section 5. Various ways of implementing playout control operations and their implications on scheduling are described in Section 6. This section also presents modifications that must be made in the basic scheduling scheme to achieve smooth transition between normal playout and operations such as ff and rw

Hardware Based Error and Flow Control in the Axon Gigabit Host-Network Interface

We have proposed a new architecture called Axon that meets the challenges of delivering high performance network bandwidth directly to applications. Its pipelines network interface must perform critical per packet processing in hardware a packets flow through the pipeline, without imposing any store-and-forward buffering of packets. This requires the design of error and flow control mechanisms to be simple enough for implementation in the network interface hardware, while providing functionality required by applications. This paper describes the implementation of the Axon host-network interface, and in particular the hardware design of the critical per packet processing with emphasis on error and flow control. An extensive simulation model of the network interface hardware has been used to determine the feasibility and performance of hardware implementation of these functions

Possible competition between superconductivity and magnetism in RuSr<SUB>2</SUB>Gd<SUB>1.5</SUB>Ce<SUB>0.5</SUB>Cu<SUB>2</SUB>O<SUB>10-&#948;</SUB> ruthenocuprate compounds

The RuSr2Gd1.5Ce0.5Cu2O10-&#948; (Ru-1222) compounds, with varying oxygen content, crystallize in a tetragonal crystal structure (space group I4/mmm). Resistance (R) versus temperature (T) measurements show that the air-annealed samples exhibit superconductivity with superconduting transition temperature (Tc) onset at around 32 K and R=0 at 3.5 K. On the other hand, the N2-annealed sample is semiconducting down to 2 K. Magneto-transport measurements on an air-annealed sample in applied magnetic fields of 3 and 6 T (Tesla) show a decrease in both Tc onset and TR=0. Magnetoresistance of up to 20% is observed in the N2-annealed sample at 2 K and 3 T applied field. The dc magnetization data (M vs T) reveal magnetic transitions (Tmag) at 100 K and 106 K, respectively, for both air- and N2-annealed samples. Ferromagnetic components in the magnetization are observed for both samples at 5 K and 20 K. The superconducting transition temperature (Tc) seems to compete with the magnetic transition temperature (Tmag). Our results suggest that the magnetic ordering temperature (Tmag) of Ru moments in RuO6 octahedra may have direct influence/connection with the appearance of superconductivity in Cu-O2 planes of Ru-1222 compounds

Mürebbiye

Hüseyin Rahmi'nin İkdam'da tefrika edilen Mürebbiye adlı roman

Structure, magnetic and transport properties of Ti-substituted La0.7Sr0.3MnO3

Ti-substituted perovskites, La0.7Sr0.3Mn1-xTixO3, with x between 0 to 0.20, were investigated by neutron diffraction, magnetization, electric resistivity, and magnetoresistance (MR) measurements. All samples show a rhombohedral structure (space group R3c) from 10 K to room temperature. At room temperature, the cell parameters a, c and the unit cell volume increase with increasing Ti content. However, at 10 K, the cell parameter a has a maximum value for x = 0.10, and decreases for x greater than 0.10, while the unit cell volume remains nearly constant for x greater than 0.10. The average (Mn,Ti)-O bond length increases up to x=0.15, and the (Mn,Ti)-O-(Mn,Ti) bond angle decreases with increasing Ti content to its minimum value at x=0.15 at room temperature. Below the Curie temperature T_C, the resistance exhibits metallic behavior for the x _ 0.05 samples. A metal (semiconductor) to insulator transition is observed for the x_ 0.10 samples. A peak in resistivity appears below T_C for all samples, and shifts to a lower temperature as x increases. The substitution of Mn by Ti decreases the 2p-3d hybridization between O and Mn ions, reduces the bandwidth W, and increases the electron-phonon coupling. Therefore, the TC shifts to a lower temperature and the resistivity increases with increasing Ti content. A field-induced shift of the resistivity maximum occurs at x less than or equal to 0.10. The maximum MR effect is about 70% for La0.7Sr0.3Mn0.8Ti0.2O3. The separation of TC and the resistivity maximum temperature Tmax enhances the MR effect in these compounds due to the weak coupling between the magnetic ordering and the resistivity as compared with La0.7Sr0.3MnO3.Comment: zip fil

Structure, Magnetic, and Transport Properties of Ti-substituted La₀.₇Sr₀.₃MnO₃

Ti-substituted perovskites La0.7Sr0.3Mn1-xTixO3 with 0 ≤ x ≤ 0.20, were investigated by neutron diffraction, magnetization, electric resistivity, and magnetoresistance (MR) measurements. All samples show a rhombohedral structure (space group R3c) from 10 K to room temperature. At room temperature, the cell parameters a,c and the unit cell volume increase with increasing Ti content. However, at 10 K, the cell parameter a has a maximum value for x = 0.10, and decreases for x \u3e 0.10, while the unit cell volume remains nearly constant for x \u3e 0.10. The average (Mn,Ti)-O bond length increases up to x = 0.15, and the (Mn,Ti)-O-(Mn,Ti) bond angle decreases with increasing Ti content to its minimum value at x = 0.15 at room temperature. Below the Curie temperature TC, the resistance exhibits metallic behavior for the x ≤ 0.05 samples. A metal (semiconductor) to insulator transition is observed for the x ≥ 0.10 samples. A peak in resistivity appears below TC for all samples, and shifts to a lower temperature as x increases. The substitution of Mn by Ti decreases the 2p-3d hybridization between O and Mn ions, reduces the bandwidth W, and increases the electron-phonon coupling. Therefore, the TC shifts to a lower temperature and the resistivity increases with increasing Ti content. A field-induced shift of the resistivity maximum occurs at x ≤ 0.10. The separation of TC and the resistivity maximum temperature Tp,max enhances the MR effect in these compounds due to the weak coupling between the magnetic ordering and the resistivity as compared with La0.7 Sr0.3MnO3