Divided disk cache and SSD FTL for improving performance in storage

Although there are many efficient techniques to minimize the speed gap between processor and the memory, it remains a bottleneck for various commercial implementations. Since secondary memory technologies are much slower than main memory, it is challenging to match memory speed to the processor. Usually, hard disk drives include semiconductor caches to improve their performance. A hit in the disk cache eliminates the mechanical seek time and rotational latency. To further improve performance a divided disk cache, subdivided between metadata and data, has been proposed previously. We propose a new algorithm to apply the SSD that is flash memory-based solid state drive by applying FTL. First, this paper evaluates the performance of such a disk cache via simulations using DiskSim. Then, we perform an experiment to evaluate the performance of the proposed algorithm.clos

Demonstration of a Bias Tunable Quantum Dots-in-a-well Focal Plane Array

Infrared detectors based on quantum wells and quantum dots have attracted a lot of attention in the past few years. Our previous research has reported on the development of the first generation of quantum dots-in-a-well (DWELL) focal plane arrays, which are based on InAs quantum dots embedded in an InGaAs well having GaAs barriers. This focal plane array has successfully generated a two-color imagery in the mid-wave infrared (i.e. 3–5 μm) and the long-wave infrared (i.e. 8–12 μm) at a fixed bias voltage. Recently, the DWELL device has been further modified by embedding InAs quantum dots in InGaAs and GaAs double wells with AlGaAs barriers, leading to a less strained InAs/InGaAs/GaAs/AlGaAs heterostructure. This is expected to improve the operating temperature while maintaining a low dark current level. This paper examines 320 × 256 double DWELL based focal plane arrays that have been fabricated and hybridized with an Indigo 9705 read-out integrated circuit using Indium-bump (flip-chip) technology. The spectral tunability is quantified by examining images and determining the transmittance ratio (equivalent to the photocurrent ratio) between mid-wave and long-way infrared filter targets. Calculations were performed for a bias range from 0.3 to 1.0 V. The results demonstrate that the mid-wave transmittance dominates at these low bias voltages, and the transmittance ratio continuously varies over different applied biases. Additionally, radiometric characterization, including array uniformity and measured noise equivalent temperature difference for the double DWELL devices is computed and compared to the same results from the original first generation DWELL. Finally, higher temperature operation is explored. Overall, the double DWELL devices had lower noise equivalent temperature difference and higher uniformity, and worked at higher temperature (70 K and 80 K) than the first generation DWELL device

Demonstration of Bias-Controlled Algorithmic Tuning of Quantum Dots in a Well (DWELL) MidIR Detectors

The quantum-confined Stark effect in intersublevel transitions present in quantum-dots-in-a-well (DWELL) detectors gives rise to a midIR spectral response that is dependent upon the detector\u27s operational bias. The spectral responses resulting from different biases exhibit spectral shifts, albeit with significant spectral overlap. A postprocessing algorithm was developed by Sakoglu that exploited this bias-dependent spectral diversity to predict the continuous and arbitrary tunability of the DWELL detector within certain limits. This paper focuses on the experimental demonstration of the DWELL-based spectral tuning algorithm. It is shown experimentally that it is possible to reconstruct the spectral content of a target electronically without using any dispersive optical elements for tuning, thereby demonstrating a DWELL-based algorithmic spectrometer. The effects of dark current, detector temperature, and bias selection on the tuning capability are also investigated experimentally

Mobile Robot Exploration in Unknown Environment using Hybrid Map

Mobile robot has the exploration function in order to perform its own task. Robot exploration can be used in many applications such as surveillance, rescue and resource detection. The workspace that robots performed in was complicated or quite wide, the multi search using the several mobile robots was mainly used. In this paper, we proposed a scheme that all areas are searched for by using one robot. The method to be proposed extract a area that can be explored in the workspace then the robot investigates the area and updates the map at the same time. The explored area is saved as a hybrid map that combines the nice attributes of the grid and topological maps. The robot can produce the safe navigation route without the obstacles by using hybrid map. The proposed hybrid map uses less memory than a grid map, but it can be used for complete coverage with the same efficiency of a topological map. Experimental results show that the proposed scheme can generate a map of an environment with only 6% of the memory that a grid map requires.clos

PMS : Prefetching Strategy for Multi-level Storage System

??????????????? ???????????? ???????????? ??????????????? ?????? ???????????? ????????? ????????? ???????????? ????????? ??????????????? ????????? ?????? ???????????? ??????. ?????? ????????? ???????????? ????????????, ?????? ?????? ???????????? ??????????????? ????????? ??? ?????? ????????????, ???????????? ???????????? ?????? ????????? ?????????????????? ????????? ???????????? ????????? ????????????. ??????????????? ???????????? ??????????????? ?????? ?????? ????????? ?????? ????????? ???????????? ?????? ????????? ????????? ?????? ??????????????????. ????????? ????????? ????????? ????????? ????????? ???????????? ????????? ??????????????? ???????????? ?????? ????????? ????????? ?????????????????? ????????? ????????? ????????? ????????? ?????? ??? ??????????????? ?????? ??? ??? ??????. ??? ??????????????? ??????????????? ????????? ????????? ?????????????????? ?????? ????????? ????????? ????????? ???????????? ??????, ?????? ????????? ????????? ??? ??????, Prefetching Strategy for Multi-level Storage system(PMS)??? ????????? ?????? ?????? ????????? ????????? ???????????????. ?????? ???????????? ?????????, ?????????????????? ?????? ?????? ???????????? ??????????????? ???????????? ????????? ?????? ?????? ???????????? ????????? ???????????? ?????????????????? ?????? ?????? ????????? ????????? ??? ??????. ?????? PMS ????????? ????????? ???????????? ?????? ??? ??????????????? ?????? ???????????? ???????????? ?????? ?????? ?????????????????? ???????????? ?????? ????????? ????????? ??????????????? ????????? ?????? ?????? 32????????? ????????? ?????????, ????????? ????????? ????????? ?????? ????????? ????????? ???????????? ?????? PMS ????????? ?????? ????????? ????????? ??????, ?????? ???????????? ??????????????? ?????? ??? ??? ?????????, ?????? 35%, ?????? 16.56%??? ?????? ??????????????? ???????????? ?????????.clos

Augmenting RAID with an SSD for Energy Relief

In this paper, we describe a design of a novel architecture for RAID that uses an SSD as a large cache to conserve energy. This approach stems from the fact that short term footprints are small enough to be efficiently managed within an SSD. More specifically, in this study, we consider two simple approaches to reduce the energy consumed in RAID. First, when a read happens in RAID, a copy of the read request is copied to the SSD, so that future requests may be serviced by the SSD. Then, for writes, all writes are buffered in SSDs so that the interval between requests may be increased reducing activities at RAID disks. We incorporate these approaches into a real implementation of a RAID 5 system that consists of four hard disks and an SSD in a Linux environment. Our preliminary results in actual performance measurements using the cello99 and SPC traces show that energy consumption is reduced by a maximum of 14%

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Mobile robots use an environment map of its workspace to complete the surveillance task. However grid-based maps that are commonly used map format for mobile robot navigation use a large size of memory for accurate representation of environment. In this reason, grid-based maps are not suitable for path planning of mobile robots using embedded board. In this paper, we present the path planning algorithm that produce a secure path rapidly. The proposed approach utilizes a hybrid map that uses less memory than grid map and has same efficiency of a topological map. Experimental results show that the fast path planning uses only 1.5% of the time that a grid map based path planning requires. And the results show a secure path for mobile robot.clos

R-Map : A hybrid map for mobile robot in ubiquitous computing environment

Building a map is an important task for service robots to process given tasks in ubiquitous computing. However, this task usually consumes lots of resources of the robots hindering the services, and also results in a partial map due to the size of the map, increasing in proportion to the complexity of the environment. For this reason a map is difficult to support different types of devices under ubiquitous computing. To share map information among the robots, a map should be small and show an entire workspace. To address this concern, we propose a hybrid map, R-Map, which is built by extracting topological information out of a grid map by a simple rule; Find the largest free rectangular area recursively in a given area. Our simulation shows that the R-map algorithm provides an accurate representation of an environment with less number of rectangles, thus efficiently reducing space complexity. © 2013 International Information Institute.ope

An Efficient Coverage Algorithm for Intelligent Robots with Deadline

This paper proposes a new coverage algorithm for intelligent robot. Many algorithms for improving the performance of coverage have been focused on minimizing the total coverage completion time. However, if one does not have enough time to finish the whole coverage,the optimal path could be different. To tackle this problem, we propose a new coverage algorithm, which we call MaxCoverage algor ithm, for covering maximal area within the deadline. The MaxCoverage algorithm decides the navigation flow by greedy algorithm for Set Covering Problem. The experimental results show that the MaxCoverage algorithm performs better than other algorithms for random deadlines.clos