Mobile devices are becoming a primary medium for personal information gathering, management, and sharing. Managing personal image data on mobile platforms is a difficult problem due to large data set size, content diversity, heterogeneous individual usage patterns, and resource constraints. This article presents a user-centric system, called iScope, for personal image management and sharing on mobile devices. iScope uses multi-modality clustering of both content and context information for efficient image management and search, and online learning techniques for predicting images of interest. It also supports distributed content-based search among networked devices while maintaining the same intuitive interface, enabling efficient information sharing among people. We have implemented iScope and conducted in-field experiments using networked Nokia N810 portable Internet tablets. Energy efficiency was a primary design focus during the design and implementation of the iScope search algorithms. Experimental results indicate that iScope improves search time and search energy by 4.1X and 3.8X on average, relative to browsing.

Minimizing power consumption is vitally important in embedded system design; power consumption determines battery lifespan. Ultra-low-power designs may even permit embedded systems to operate without batteries by scavenging energy from the environment. Moreover, managing power dissipation is now a key factor in integrated circuit packaging and cooling. As a result, embedded system price, size, weight, and reliability are all strongly dependent on power dissipation. Recent developments in nanoscale devices open new alternatives for low-power embedded system design. Among these, single-electron tunneling transistors (SETs) hold the promise of achieving the lowest power consumption. Unfortunately, most analysis of SETs has focused on single devices instead of architectures, making it difficult to determine whether they are appropriate for low-power embedded systems. Evaluating the use of SETs in large-scale digital systems requires novel architectural and circuit design. SET-based design imposes numerous challenges resulting from low driving strength, relatively large static power consumption, and the presence of reliability problems resulting from random background charge effects. We propose a fault-tolerant, hybrid SET/CMOS, reconfigurable architecture, named IceFlex, that can be tailored to specific requirements and allows tradeoffs among power consumption, performance requirements, operation temperature, fabrication cost, and reliability. Using IceFlex as a testbed, we characterize the benefits and limitations of SETs in embedded system designs. In particular, we focus on the use of SETs in room-temperature ultra-low-power embedded systems such as wireless sensor network nodes. We also consider high-performance applications such as multimedia consumer electronics. We see this work as a first step in determining the potential of ultra-low-power embedded system design using SETs.

Three-dimensional integration has the potential to improve the communication latency and integration density of chip-level multiprocessors (CMPs). However, the stacked high-power density layers of 3D CMPs increase the importance and difficulty of thermal management. In this paper, we investigate the 3D CMP run-time thermal management problem and describe efficient management techniques. This paper makes the following main contributions: 1) It identifies and describes the critical concepts required for optimal thermal management, namely the methods by which heterogeneity in both workload power characteristics and processor core thermal characteristics should be exploited; and 2) it proposes an efficient proactive continuously engaged hardware and operating system thermal management technique governed by optimal thermal management polices. The proposed technique is evaluated using multiprogrammed and multithreaded benchmarks in an integrated power, performance, and temperature full-system simulation environment. We find that proactive power-thermal budgeting allows a 30% improvement in instruction throughput compared to a proactive thermal management approach that bases decisions only upon local information. The software components of the proposed thermal management technique have been implemented in the Linux 2.6.8 kernel. This source code will be publicly released. The analysis and technique developed in this paper provide a general solution for future 3D and 2D CMPs.

This paper presents modeling and estimation techniques permitting the temperature-aware optimization of application-specific multiprocessor system-on-chip (MPSoC) reliability. Technology scaling and increasing power densities make MPSoC lifetime reliability problems more severe. MPSoC reliability strongly depends on system-level MPSoC architecture, redundancy, and thermal profile during operation. We propose an efficient temperature-aware MPSoC reliability analysis and prediction technique that enables MPSoC reliability optimization via redundancy and temperature-aware design planning. Reliability, performance, and area are concurrently optimized. Simulation results indicate that the proposed approach has the potential to substantially improve MPSoC system mean time to failure with small area overhead.

Minimizing power consumption is vitally important in embedded system design; power consumption determines battery lifespan. Ultra-low-power designs may even permit embedded systems to operate without batteries, e.g., by scavenging energy from the environment. Moreover, managing power dissipation is now a key factor in integrated circuit packaging and cooling. As a result, embedded system price, size, weight, and reliability are all strongly dependent on power dissipation.

Ever-increasing integrated circuit (IC) power densities and peak temperatures threaten reliability, performance, and economical cooling. To address these challenges, thermal analysis must be embedded within IC synthesis. However, this requires accurate three-dimensional chip-package heat flow analysis. This has typically been based on numerical methods that are too computationally intensive for numerous repeated applications during synthesis or design. Thermal analysis techniques must be both accurate and fast for use in IC synthesis. This paper presents a novel accurate incremental spatially and temporally adaptive chip-package thermal analysis technique called ISAC for use in IC synthesis and design. It is common for IC temperature variation to strongly depend on position and time. ISAC dynamically adapts spatial- and temporal-modeling granularities to achieve high efficiency while maintaining accuracy. Both steady-state and dynamic thermal analyses are accelerated by the proposed heterogeneous spatial-resolution adaptation and asynchronous thermal-element time-marching techniques. Each technique enables orders-of-magnitude improvement in performance while preserving accuracy when compared with other state-of-the-art adaptive steady-state and dynamic IC thermal analysis techniques. Experimental results indicate that these improvements are sufficient to make accurate dynamic and steady-state thermal analysis practical within the inner loops of IC synthesis algorithms. ISAC has been validated against reliable commercial thermal analysis tools using industrial and academic synthesis test cases and chip designs. It has been implemented as a software package suitable for integration in IC synthesis and design flows and has been publicly released

Ever-increasing integrated circuit(IC) power densities and peak temperatures threaten reliability, performance, and economical cooling. To address these challenges, thermal analysis must be embedded within IC synthesis. However, detailed thermal analysis requires accurate three-dimensional chip-package heat flow analysis. This has typically been based on numerical methods that are too computationally intensive for numerous repeated applications during synthesis or design. Thermal analysis techniques must be both accurate and fast for use in IC synthesis. This article presents a novel, accurate, incremental, self-adaptive, chip-package thermal analysis technique, called ISAC, for use in IC synthesis and design. It is common for IC temperature variation to strongly depend on position and time. ISAC dynamically adapts spatial and temporal modeling granularity to achieve high efficiency while maintaining accuracy. Both steady-state and dynamic thermal analysis are accelerated by the proposed heterogeneous spatial resolution adaptation and temporally decoupled element time marching techniques. Each technique enables orders of magnitude improvement in performance while preserving accuracy when compared with other state-of-the-art adaptive steady-state and dynamic IC thermal analysis techniques. Experimental results indicate that these improvements are sufficient to make accurate dynamic and static thermal analysis practical with in the inner loops of IC synthesis algorithms. ISAC has been validated against reliable commercial thermal analysis tools using industrial and academic synthesis test cases and chip designs. It has been implemented as a software package suitable for integration in IC synthesis and design flows and has been publicly released.

Chip-package thermal analysis is necessary for the design and synthesis of reliable, high-performance, low-power, compact integrated circuits (ICs). Many methods of IC thermal analysis suffer performance or accuracy problems that prevent use in IC synthesis and hinder use in architectural design.