An interconnecting bus power optimization method combining interconnect wire spacing with wire ordering

On-chip interconnect buses consume tens of percents of dynamic power in a nanometer scale integrated circuit and they will consume more power with the rapid scaling down of technology size and continuously rising clock frequency, therefore it is meaningful to lower the interconnecting bus power in design. In this paper, a simple yet accurate interconnect parasitic capacitance model is presented first and then, based on this model, a novel interconnecting bus optimization method is proposed. Wire spacing is a process for spacing wires for minimum dynamic power, while wire ordering is a process that searches for wire orders that maximally enhance it. The method, i.e., combining wire spacing with wire ordering, focuses on bus dynamic power optimization with a consideration of bus performance requirements. The optimization method is verified based on various nanometer technology parameters, showing that with 50% slack of routing space, 25.71% and 32.65% of power can be saved on average by the proposed optimization method for a global bus and an intermediate bus, respectively, under a 65-nm technology node, compared with 21.78% and 27.68% of power saved on average by uniform spacing technology. The proposed method is especially suitable for computer-aided design of nanometer scale on-chip buses.

Influence of wire spacing and plate spacing on electrostatic precipitation of nanoparticles: An approach involving electrostatic shielding and diffusion charging

Electrostatic precipitation is a process widely used as gas cleaning device,to removal particles from gas flows.However,in a conventional and well-sized precipitator,the collection efficiency decreases for ultrafine particles,making it difficult to employ this equipment for controlling nanoparticle pollution.This paper investigates the influence of plate spacing(4 and 6.5 cm)and wire spacing(4,6,and 12 cm)on the electric current and nanoparticle collection efficiency,considering the effect of diffusion charging and electrostatic shielding.Two laboratory-scale dry wire-plate electrostatic precipitators with different plate spacings were tested for the collection of nanoparticles(6.15–241.4 nm)at three air velocities(1.9,2.9,and 3.9 cm/s).The results demonstrated the effectiveness of the equipment in removing nanoparticles(99.9%)under the highest electric fields.Higher values of the wire spacing led to increases in the current and the collection efficiency.This was associated with reduced electrostatic shielding,which is more evident in smaller ducts with a higher density of field lines.It is expected that the findings should improve knowledge on electrostatic precipitation of nanoparticles,enabling optimization of collection efficiency by considering the effects of geometric parameters.

Multi-objective optimization of gradient coil for benchtop magnetic resonance imaging system with high-resolution

Significant high magnetic gradient field strength is essential to obtaining high-resolution images in a benchtop mag- netic resonance imaging （BT-MRI） system with permanent magnet. Extending minimum wire spacing and maximum wire width of gradient coils is one of the key solutions to minimize the maximum current density so as to reduce the local heating and generate higher magnetic field gradient strength. However, maximum current density is hard to optimize together with field linearity, stored magnetic energy, and power dissipation by the traditional target field method. In this paper, a new multi-objective method is proposed to optimize the maximum current density, field linearity, stored magnetic energy, and power dissipation in MRI gradient coils. The simulation and experimental results show that the minimum wire spacings are improved by 159% and 62% for the transverse and longitudinal gradient coil respectively. The maximum wire width increases from 0.5 mm to 1.5 mm. Maximum gradient field strengths of 157 mT/m and 405 mT/m for transverse and lon- gitudinal coil are achieved, respectively. The experimental results in BT-MRI instrument demonstrate that the MRI images with in-plane resolution of 50 ~tm can be obtained by using the designed coils.