Dynamic and Leakage Power-Composition Profile Driven Co-Synthesis for Energy and Cost Reduction

Recent research has shown that combining dynamic voltage scaling (DVS) and adaptive body bias (ABB) techniques achieve the highest reduction in embedded systems energy dissipation [1]. In this paper we show that it is possible to produce comparable energy saving to that obtained using combined DVS and ABB techniques but with reduced hardware cost achieved by employing processing elements (PEs) with separate DVS or ABB capability. A co-synthesis methodology which is aware of tasks’ power-composition profile (the ratio of the dynamic power to the leakage power) is presented. The methodology selects voltage scaling capabilities (DVS, ABB, or combined DVS and ABB) for the PEs, maps, schedules, and voltage scales applications given as task graphs with timing constraints, aiming to dynamic and leakage energy reduction at low hardware cost. We conduct detailed experiments, including a real-life example, to demonstrate the effectiveness of our methodology. We demonstrate that it is possible to produce designs that contain PEs with only DVS or ABB technique but have energy dissipation that are only 4.4% higher when compared with the same designs that employ PEs with combined DVS and ABB capabilities

Cellulose based materials to accelerate the transition towards sustainability

Several significant sectors use cellulose, including paper manufacturing, cellophane, textiles (including rayon and viscose), and food and medicine additives. It can be utilised as a raw materials in production of fuel sources like cellulosic ethanol. Crystalline cellulose possesses a tensile strength of about 7.5 GPa, Young’s modulus of 110-220 GPa and as the most abundantly available natural polymer, with excellent biocompatibility, good degradation and regeneration properties, it is considered as a remarkable biomaterial. Cellulose-based materials can be fabricated with tuneable magnetic properties, electrical conductivity, photosensitivity, sensing abilities, catalytic activity, and other specific properties by incorporating nanoparticles. These qualities make cellulose a sustainable multifunctional material. To harness such properties, strenuous efforts are being made to manufacture cellulose based materials through a wide number of manufacturing processes. This review provides an overview of the current readiness in producing cellulose-based functional materials by surveying the manufacturing procedures, characteristics and their potential applications for the end users. Future directions and opportunities of work are suggested and the limitations inherent with every process and the challenges that needs to be overcome in scalable manufacturing of cellulose-based materials are also discussed

Linear-nonlinear stiffness responses of carbon fiber-reinforced polymer composite materials and structures: a numerical study

The stiffness response or load-deformation/displacement behavior is the most important mechanical behavior that frequently being utilized for validation of the mathematical-physical models representing the mechanical behavior of solid objects in numerical method, compared to actual experimental data. This numerical study aims to investigate the linear-nonlinear stiffness behavior of carbon fiber-reinforced polymer (CFRP) composites at material and structural levels, and its dependency to the sets of individual/group elastic and damage model parameters. In this regard, a validated constitutive damage model, elastic-damage properties as reference data, and simulation process, that account for elastic, yielding, and damage evolution, are considered in the finite element model development process. The linear-nonlinear stiffness responses of four cases are examined, including a unidirectional CFRP composite laminate (material level) under tensile load, and also three multidirectional composite structures under flexural loads. The result indicated a direct dependency of the stiffness response at the material level to the elastic properties. However, the stiffness behavior of the composite structures depends both on the structural configuration, geometry, lay-ups as well as the mechanical properties of the CFRP composite. The value of maximum reaction force and displacement of the composite structures, as well as the nonlinear response of the structures are highly dependent not only to the mechanical properties, but also to the geometry and the configuration of the structures

Assessment of Mixing in Passive Microchannels with Fractal Surface Patterning

We explore numerically the feasibility of enhancing the mixing capability of microchannels by employing the Weierstrass fractal function to generate a pattern of V-shaped ridges on the channel floor. Motivated by experimental limitations such as the finite resolution (similar to 10 mu m) associated with rapid prototyping through soft lithography techniques, we study the influence on the quality of mixing of having finite width ridges. The mixing capability of the designs studied is evaluated using an entropic measure and the designs are optimized with respect to: the distances between the ridges and the position range of their tip along the width of the channels. The results are evaluated with respect to the benchmarks established by the very successful staggered herring bone (SHB) design. We find that the use of a non periodic protocol to generate the geometry of the bottom surface of the microchannels can lead to consistently larger entropic mixing indices than in cyclic structures. Furthermore, since the optimization curves (mixing index vs. geometric parameters) are broader at the maximum for fractal microchannels than for their SHB counterparts, the microchannel designs using the Weierstrass fractal function are less sensitive to experimental uncertainties