No abstract

No abstract

ABSTRACT3D stacked wafer integration has the potential to improve multiprocessor system-on-chip (MPSoC) integration density, performance, and power efficiency. However, the power density of 3D MPSoCs increases with the number of active layers, resulting in high chip temperatures. This can reduce system reliability, reduce performance, and increase cooling cost. Thermal optimization for 3D MPSoCs imposes numerous challenges. It is difficult to manage assignment and scheduling of heterogeneous workloads to maintain thermal safety. In addition, the thermal characteristics of 3D MPSoCs differ from those of 2D MPSoCs because each stacked layer has a different thermal resistance to the ambient and verticallyadjacent processors have strong temperature correlation.We propose a 3D MPSoC thermal optimization algorithm that conducts task assignment, scheduling, and voltage scaling. A power balancing algorithm is initially used to distribute tasks among cores and active layers. Detailed thermal analysis is used to guide a hotspot mitigation algorithm that incrementally reduces the peak MPSoC temperature by appropriately adjusting task execution times and voltage levels. The proposed algorithm considers leakage power consumption and adapts to inter-layer thermal heterogeneity. Performance evaluation on a set of multiprogrammed and multithreaded benchmarks indicates that the proposed techniques can optimize 3D MPSoC power consumption, power profile, and chip peak temperature.

The effect of lattice mismatch on the chemical ordering of epitaxial FePt films was studied. The results showed that the lattice constant (c) of the FePt films decreased with increasing lattice mismatch ε from about 2.23% to 6.33%. Upon further increase of ε to about 8.8%, c increased. On the other hand, the variation of the lattice constant (a) of the FePt films showed a reversal behavior to that of c with the increased lattice mismatch. The ratio c∕a of the FePt films held a minimum of about 0.9466, while the chemical ordering degree and magnetic anisotropy constant held maximum values for ε around 6.33%. These results indicated that the strain from the lattice mismatch favored the ordering of the FePt films.

In this work, we demonstrate a simple and effective method to design and realize various Weyl semimetal (WSM) states in a three-dimensional periodic circuit lattice composed of passive electric circuit elements such as inductors and capacitors (LC). The experimental accessibility of such LC circuits offers a ready platform for the realization of not only various WSM phases but also for exploring transport properties in topological systems. The characteristics of such LC circuits are described by the circuit admittance matrices, which are mathematically related to the Hamiltonian of the quantum tight-binding model. The system can be switched between the Type-I and Type-II WSM phases simply by an appropriate choice of inductive or capacitive coupling between certain nodes. A peculiar phase with a flat admittance band emerges at the transition between the Type-I and Type-II Weyl phases. Impedance resonances occur in the LC circuits at certain frequencies associated with vanishing eigenvalues of the admittance matrix. The impedance readout can be used to classify the Type-I and Type-II WSM states. A Type-I WSM shows impedance peaks only at the Weyl points (WPs) whereas a Type-II WSM exhibits multiple secondary peaks near the WPs. This impedance behaviour reflects the vanishing and non-vanishing density of states at the Weyl nodes in the Type-I and Type-II WSM phases, respectively.

The current research proposed the theoretical model for ship twin-propeller jet based on the axial momentum theory and Gaussian normal distribution. The twin-propeller jet model is compared to the more matured single propeller jet model with good agreement. Computational Fluid Dynamics (CFD) method is used to acquire the velocity distribution within the twin-propeller jet for understanding of flow characteristics and validation purposes. Efflux velocity is the maximum velocity within the entire jet with strong influences by the geometrical profiles of the blades. Twin-propeller jet model showed four-peaked profile at the initial plane downstream to the propeller compared to the two-peaked profile from a single-propeller. The four-peaked profile merges to be two-peaked velocity profile and then one-peaked profile due to the fluid mixing. Entrainment occurs between the ambient still water outside and the rotating flow within jet due to the high velocity gradient. The research proposes a twin-propeller jet theory with a serial of equations enabling the predictions of velocity magnitude within the jet.

No abstract

No abstract