IEEE transactions on computer-aided design of integrated circuits and systems : a publication of the IEEE Circuits and Systems Society

Optimization problems relating to wireless sensor network planning, design, deployment and operation often give rise to multi-objective optimization formulations where multiple desirable objectives compete with each other and the decision maker has to select one of the tradeoff solutions. These multiple objectives may or may not conflict with each other. Keeping in view the nature of the application, the sensing scenario and input/output of the problem, the type of optimization problem changes. To address different nature of optimization problems relating to wireless sensor network design, deployment, operation, planing and placement, there exist a plethora of optimization solution types. We review and analyze different desirable objectives to show whether they conflict with each other, support each other or they are design dependent. We also present a generic multi-objective optimization problem relating to wireless sensor network which consists of input variables, required output, objectives and constraints. A list of constraints is also presented to give an overview of different constraints which are considered while formulating the optimization problems in wireless sensor networks. Keeping in view the multi facet coverage of this article relating to multi-objective optimization, this will open up new avenues of research in the area of multi-objective optimization relating to wireless sensor networks.

https://www.mdpi.com/1424-8220/15/7/17572/pdf

Wireless Sensor Network Optimization: Multi-Objective Paradigm.

Liquid-cooling using microchannel heat sinks etched on silicon dies is seen as a promising solution to the rising heat fluxes in two-dimensional and stacked three-dimensional integrated circuits. Development of such devices requires accurate and fast thermal simulators suitable for early-stage design. To this end, we present 3D-ICE, a compact transient thermal model (CTTM), for liquid-cooled ICs. 3D-ICE was first advanced incorporating the 4-resistor model-based CTTM (4RM-based CTTM). Later, it was enhanced to speed up simulations and to include complex heat sink geometries such as pin fins using the new 2 resistor model (2RM-based CTTM). In this paper, we extend the 3D-ICE model to include liquid-cooled ICs with multi-port cavities, i.e., cavities with more than one inlet and one outlet ports, and non-straight microchannels. Simulation studies using a realistic 3D multiprocessor system-on-chip (MPSoC) with a 4-port microchannel cavity highlight the impact of using 4-port cavity on temperature and also demonstrate the superior performance of 2RM-based CTTM compared to 4RM-based CTTM. We also present an extensive review of existing literature and the derivation of the 3D-ICE model, creating a comprehensive study of liquid-cooled ICs and their thermal simulation from the perspective of computer systems design. Finally, the accuracy of 3D-ICE has been evaluated against measurements from a real liquid-cooled 3D-IC, which is the first such validation of a simulator of this genre. Results show strong agreement (average error ${\bf \lt 10\%}$ ), demonstrating that 3D-ICE is an effective tool for early-stage thermal-aware design of liquid-cooled 2D-/3D-ICs.

/pdf/3d-ice-a-compact-thermal-model-for-early-stage-design-of-1j49ti1oxf.pdf

3D-ICE: A Compact Thermal Model for Early-Stage Design of Liquid-Cooled ICs

A novel thermal management scheme for 3D-IC chips with multi-cores and high power density

Multi-objective optimization in sensor networks

3-D stacked systems reduce communication delay in multiprocessor system-on-chips (MPSoCs) and enable heterogeneous integration of cores, memories, sensors, and RF devices. However, vertical integration of layers exacerbates temperature-induced problems such as reliability degradation. Liquid cooling is a highly efficient solution to overcome the accelerated thermal problems in 3-D architectures; however, it brings new challenges in modeling and run-time management for such 3-D MPSoCs with multitier liquid cooling. This paper proposes a novel design-time/run-time thermal management strategy. The design-time phase involves a rigorous thermal impact analysis of various thermal control variables. We then utilize this analysis to design a run-time fuzzy controller for improving energy efficiency in 3-D MPSoCs through liquid cooling management and dynamic voltage and frequency scaling (DVFS). The fuzzy controller adjusts the liquid flow rate dynamically to match the cooling demand of the chip for preventing overcooling and for maintaining a stable thermal profile. The DVFS decisions increase chip-level energy savings and help balance the temperature across the system. Our controller is used in conjunction with temperature-aware load balancing and dynamic power management strategies. Experimental results on 2-tier and 4-tier 3-D MPSoCs show that our strategy prevents the system from exceeding the given threshold temperature. At the same time, we reduce cooling energy by up to 63% and system-level energy by up to 21% in comparison to statically setting a flow rate setting to handle worst-case temperatures.

/pdf/energy-efficient-multiobjective-thermal-control-for-liquid-3x48vdjk0z.pdf

M. M. Sabry

Papers

Energy-Efficient Multiobjective Thermal Control for Liquid-Cooled 3-D Stacked Architectures