Self-similarity is a property of physical systems that describes how to scale parameters such that dissimilar systems appear to be similar. Computer systems are self-similar if certain ratios of computational forces, also known as computational intensities, are equal. Two machines with different computational power, different network bandwidth and different inter-processor latency behave the same way if they have the same ratios of forces. For the parallel conjugate gradient algorithm studied in this paper, two machines are self-similar if and only if the ratio of one force describing latency effects to another force describing bandwidth effects is the same for both machines. For the two machines studied in this paper, this ratio, which we call the mixing coefficient, is invariant as problem size and processor count change. The two machines have the same mixing coefficient and belong to the same equivalence class. 相似文献
The induced-charge electrokinetic flow (ICEKF) in a rectangular micorchannel with a pair of conducting triangle hurdles embedded
in the middle is investigated in this paper. A correction method is suggested to numerically estimate the induced zeta potential
on the conducting surface. Two-dimensional pressure-linked Navier-–Stokes equation is used to model the flow field in the
channel. The numerical results show flow circulations generated from the induced non-uniform zeta potential distribution along
the conducting hurdle surfaces. It is demonstrated numerically that the local flow circulations provide effective means to
enhance the flow mixing between different solutions; by adjusting the electric field applied through the microchannel with
a non-symmetric triangle hurdle pair, an electrokinetic flow regulating effect can be obtained and this effect depends on
the dimensions of the conducting converging–diverging section. The mixing and flow regulating using ICEKF described in this
paper can be used in various microfluidics and lab-on-a-chip (LOC) applications. 相似文献
The strategic approach of this article is to characterize the continuous-flow mixing of pseudoplastic fluids possessing yield stress in a stirred reactor with the Maxblend impeller. Dynamic experiments were carried out through the frequency-modulated random binary input of a brine solution to determine the extent of non-ideal flows. Mixing quality was determined on the basis of the extent of channeling and fully mixed volume. The effects of important parameters such as impeller speed (25–500 rpm), absence of baffles, fluid rheology (0.5–1.5%), fluid flow rate (3.20–14.17 L min−1), and the locations of inlet/outlet on the dynamic performance of the continuous-flow mixing vessel were explored. The performance of the Maxblend impeller was then compared to the performances of various types of impellers such as close-clearance (an anchor), axial-flow (a Lightnin A320), and radial-flow (a Scaba 6SRGT) impellers. It was found when the channeling approached zero and the fully mixed volume approached the total fluid volume in the vessel, the power drawn by the A320 impeller and the Scaba impeller were about 2.9 and 4.3 times greater than that of the Maxblend impeller. Thus, the Maxblend impeller was able to drastically improve the performance of continuous-flow mixing with huge power savings. The mixing quality was further improved by optimizing the impeller speed, decreasing the fluid flow rate, decreasing the fluid concentration, and using bottom inlet- top outlet configuration. The flow non-ideality of the mixing system increased in the absence of the baffles. Thus, better mixing quality and more energy savings can be achieved by employing the findings of this study. 相似文献
This work describes new type of combustion instability for which the 3-way coupling between mixing, flame heat release, and acoustics is modified by local buoyancy effects. Measurements of fuel mixture fraction are made for a non-premixed jet flame in a combustion chamber to assess the dynamics of mixing under imposed acoustic oscillations (22-55 Hz). Infrared laser absorption and phase resolved acetone-planar laser induced fluorescence are used to measure the fuel mixture fraction and then the degree of fuel/air mixing is calculated by determining the unmixedness. Results show acoustic excitation causes oscillations in the degree of fuel/air mixing at the driving frequency, which results in oscillatory flame behavior. This oscillatory flame behavior couples to the buoyancy and this in turn affects the mixing. Results also show that the mixing becomes less effective when the excitation frequency is increased or when the flame is present, compared to the non-reacting case. This work describes a key coupling mechanism that occurs when buoyancy is a significant factor in the flow field. 相似文献
Two equiatomic high entropy alloys, AlCrCuNixTi (x?=?0, 1), were prepared by an arc furnace. Their microstructure, thermodynamics and compressive properties were investigated in as-cast state. The AlCrCuTi alloy consists of a face centred cubic (fcc) phase, two body centred cubic (bcc) phases and an Al4Cu9-like phase, while the AlCrCuNiTi alloy contains an fcc phase and two bcc phases. Thermodynamic expressions based on mixing enthalpy matrix facilitate the thermodynamic calculation. The element Cr takes severe segregation during solidification and forms Cr rich phases in both alloys. The addition of Ni to the AlCrCuNiTi alloy inhibits the formation of intermetallic compounds and enhances the yield strength, compressive strength and ultimate strain, but degrades Vickers hardness. 相似文献
Context: Regulatory agencies are recommending the development of process analytical technologies (PAT) to improve the efficiency and product quality during pharmaceutical manufacturing.
Objective: The objective of the research was to investigate the potential application of passive acoustic emission monitoring of a V-blender.
Materials and methods: Trials were conducted with sugar spheres, lactose or MCC in a V-blender. Vibrations from acoustic emissions were measured using PCB Piezotronics accelerometers with ICP signal conditioners.
Results and discussion: A wavelet filter was applied to the measured acoustic emissions to remove vibrations from the tumbling motion of the V-shell, allowing a focus on information about particle motion and interactions within the V-shell. The ideal sensor location was determined to be the lid of one of the V-shell arms due to the impact of the tumbling particles on the lid and transmission of the vibrations from other particle motion within the V-shell. The amplitude of vibrations increased with particle size due to larger particle momentum before a collision. The fill level and the V-shell scale also influenced the measured vibrations as particle motion was affected which in turn affected momentum. Changes in particle flowability could be detected through variations in the measured acoustic emissions.
Conclusion: The measured vibrations from passive acoustic emissions reflected particle motion and interactions within a V-blender demonstrating potential as a monitoring method. 相似文献