A Survey of Techniques For Improving Energy Efficiency in Embedded Computing Systems

Recent technological advances have greatly improved the performance and features of embedded systems. With the number of just mobile devices now reaching nearly equal to the population of earth, embedded systems have truly become ubiquitous. These trends, however, have also made the task of managing their power consumption extremely challenging. In recent years, several techniques have been proposed to address this issue. In this paper, we survey the techniques for managing power consumption of embedded systems. We discuss the need of power management and provide a classification of the techniques on several important parameters to highlight their similarities and differences. This paper is intended to help the researchers and application-developers in gaining insights into the working of power management techniques and designing even more efficient high-performance embedded systems of tomorrow

An Ultra-Low-Energy, Variation-Tolerant FPGA Architecture Using Component-Specific Mapping

As feature sizes scale toward atomic limits, parameter variation continues to increase, leading to increased margins in both delay and energy. Parameter variation both slows down devices and causes devices to fail. For applications that require high performance, the possibility of very slow devices on critical paths forces designers to reduce clock speed in order to meet timing. For an important and emerging class of applications that target energy-minimal operation at the cost of delay, the impact of variation-induced defects at very low voltages mandates the sizing up of transistors and operation at higher voltages to maintain functionality. With post-fabrication configurability, FPGAs have the opportunity to self-measure the impact of variation, determining the speed and functionality of each individual resource. Given that information, a delay-aware router can use slow devices on non-critical paths, fast devices on critical paths, and avoid known defects. By mapping each component individually and customizing designs to a component's unique physical characteristics, we demonstrate that we can eliminate delay margins and reduce energy margins caused by variation. To quantify the potential benefit we might gain from component-specific mapping, we first measure the margins associated with parameter variation, and then focus primarily on the energy benefits of FPGA delay-aware routing over a wide range of predictive technologies (45 nm--12 nm) for the Toronto20 benchmark set. We show that relative to delay-oblivious routing, delay-aware routing without any significant optimizations can reduce minimum energy/operation by 1.72x at 22 nm. We demonstrate how to construct an FPGA architecture specifically tailored to further increase the minimum energy savings of component-specific mapping by using the following techniques: power gating, gate sizing, interconnect sparing, and LUT remapping. With all optimizations considered we show a minimum energy/operation savings of 2.66x at 22 nm, or 1.68--2.95x when considered across 45--12 nm. As there are many challenges to measuring resource delays and mapping per chip, we discuss methods that may make component-specific mapping more practical. We demonstrate that a simpler, defect-aware routing achieves 70% of the energy savings of delay-aware routing. Finally, we show that without variation tolerance, scaling from 16 nm to 12 nm results in a net increase in minimum energy/operation; component-specific mapping, however, can extend minimum energy/operation scaling to 12 nm and possibly beyond.</p

CAD Techniques for Robust FPGA Design Under Variability

The imperfections in the semiconductor fabrication process and uncertainty in operating environment of VLSI circuits have emerged as critical challenges for the semiconductor industry. These are generally termed as process and environment variations, which lead to uncertainty in performance and unreliable operation of the circuits. These problems have been further aggravated in scaled nanometer technologies due to increased process variations and reduced operating voltage. Several techniques have been proposed recently for designing digital VLSI circuits under variability. However, most of them have targeted ASICs and custom designs. The flexibility of reconfiguration and unknown end application in FPGAs make design under variability different for FPGAs compared to ASICs and custom designs, and the techniques proposed for ASICs and custom designs cannot be directly applied to FPGAs. An important design consideration is to minimize the modifications in architecture and circuit to reduce the cost of changing the existing FPGA architecture and circuit. The focus of this work can be divided into three principal categories, which are, improving timing yield under process variations, improving power yield under process variations and improving the voltage profile in the FPGA power grid. The work on timing yield improvement proposes routing architecture enhancements along with CAD techniques to improve the timing yield of FPGA designs. The work on power yield improvement for FPGAs selects a low power dual-Vdd FPGA design as the baseline FPGA architecture for developing power yield enhancement techniques. It proposes CAD techniques to improve the power yield of FPGAs. A mathematical programming technique is proposed to determine the parameters of the buffers in the interconnect such as the sizes of the transistors and threshold voltage of the transistors, all within constraints, such that the leakage variability is minimized under delay constraints. Two CAD techniques are investigated and proposed to improve the supply voltage profile of the power grids in FPGAs. The first technique is a place and route technique and the second technique is a logic clustering technique to reduce IR-drops and spatial variation of supply voltage in the power grid

POWER-AWARE TECHNOLOGY MAPPING AND ROUTING FOR DUAL-VT FPGAS

Master'sMASTER OF ENGINEERIN

Leakage Power Modeling and Reduction Techniques for Field Programmable Gate Arrays

FPGAs have become quite popular for implementing digital circuits and systems because of reduced costs and fast design cycles. This has led to increased complexity of FPGAs, and with technology scaling, many new challenges have come up for the FPGA industry, leakage power being one of the key challenges. The current generation FPGAs are being implemented in 90nm technology, therefore, managing leakage power in deep-submicron FPGAs has become critical for the FPGA industry to remain competitive in the semiconductor market and to enter the mobile applications domain. In this work an analytical state dependent leakage power model for FPGAs is developed, followed by dual-Vt based designs of the FPGA architecture for reducing leakage power. The leakage power model computes subthreshold and gate leakage in FPGAs, since these are the two dominant components of total leakage power in the scaled nanometer technologies. The leakage power model takes into account the dependency of gate and subthreshold leakage on the state of the circuit inputs. The leakage power model has two main components, one which computes the probability of a state for a particular FPGA circuit element, and the other which computes the leakage of the FPGA circuit element for a given input using analytical equations. This FPGA power model is particularly important for rapidly analyzing various FPGA architectures across different technology nodes. Dual-Vt based designs of the FPGA architecture are proposed, developed, and evaluated, for reducing the leakage power using a CAD framework. The logic and the routing resources of the FPGA are considered for dual-Vt assignment. The number of the logic elements that can be assigned high-Vt in the ideal case by using a dual-Vt assignment algorithm in the CAD framework is estimated. Based upon this estimate two kinds of architectures are developed and evaluated, homogeneous and heterogeneous architectures. Results indicate that leakage power savings of up to 50% can be obtained from these architectures. The analytical state dependent leakage power model developed has been used for estimating the leakage power savings from the dual-Vt FPGA architectures. The CAD framework that has been developed can also be used for developing and evaluating different dual-Vt FPGA architectures, other than the ones proposed in this work

Hardware Considerations for Signal Processing Systems: A Step Toward the Unconventional.

As we progress into the future, signal processing algorithms are becoming more computationally intensive and power hungry while the desire for mobile products and low power devices is also increasing. An integrated ASIC solution is one of the primary ways chip developers can improve performance and add functionality while keeping the power budget low. This work discusses ASIC hardware for both conventional and unconventional signal processing systems, and how integration, error resilience, emerging devices, and new algorithms can be leveraged by signal processing systems to further improve performance and enable new applications. Specifically this work presents three case studies: 1) a conventional and highly parallel mix signal cross-correlator ASIC for a weather satellite performing real-time synthetic aperture imaging, 2) an unconventional native stochastic computing architecture enabled by memristors, and 3) two unconventional sparse neural network ASICs for feature extraction and object classification. As improvements from technology scaling alone slow down, and the demand for energy efficient mobile electronics increases, such optimization techniques at the device, circuit, and system level will become more critical to advance signal processing capabilities in the future.PhDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/116685/1/knagphil_1.pd

Ekstraksi Fitur Conflict of Interest pada Artikel Ilmiah Untuk Menentukan Kualitas Citation Author

Sitasi pada publikasi ilmiah mempengaruhi kualitas artikel sehingga akanberpengaruh terhadap kredibilitas author (peneliti). Terda pat banyak cara untuk meningkatkan kredibilitas peneliti, salah satunya adalah dengan melakukan sitasi terhadap diri sendiri (self citation). Namun, proses self citation yang berlebihan mengurangi kualitas sitasi paper tersebut. Terdapat banyak penelitian yang membuat metode untuk mengukur kualitas self-citation yang tidak sesuai, salah satunya dengan menggunakan rasio self-citation pada jendela waktu. Akan tetapi, metode ini tidak mempertimbangkan kesesuaian topik penelitian paper utama terhadap paper yang mensitasinya. Sehingga diperlukan adanya penentuan kualitas sitasi pada author agar dapat diketahui apakah peneliti sering meggunakan citation yang tidak sesuai topiknya berdasarkan paper author dan paper sitasi. Penelitian ini mengusulkan metode ekstraksi fitur conflict of interest untuk menentukan kualitas citation penulis artikel ilmiah. Hal ini dilakukan untuk mengetahui seberapa baik peneliti dalam menggunakan sitasinya. Terdapat 2 fitur yang diusulkan dalam penelitian ini. Pertama, fitur confict of interest yang didapatkan dari konflik kepentingan antara author paper dan author paper yang disitasi. Kedua, fitur similaritas konten yaitu fitur yang didapatkan dari kesamaan topik antar dokumen paper dan yang disitasinya. Metode similaritas yang digunakan adalah salah satu pendekatan deep learning yaitu Siamese Neural Network yang dikombinasikan dengan Long Short Term Memory. Kedua fitur ini selanjutnya diklasifikasi untuk menentukan kualitas citation author. Seluruh fitur akan diuji performanya pada proses klasifikasi. Hasil klasifikasi selanjutnya akan dihitung nilai akurasinya untuk mendapatkan performa fitur yang diusulkan. Hasil uji coba menunjukkan bahwa usulan fitur dapat digunakan untuk mengklasifikasi kualitas sitasi author. Hal ini ditunjukkan dengan nilai akurasi sebesar 66.67% pada klasifikasi Random Forest dan rata-rata akurasi sebesar 62% pada 3 klasifikasi yang digunakan. =================================================================================================== Citation on scientific paper affect on article quality so that it will affect on author credibility. There are many ways to increase the credibility of researchers, one of them is to do a self-citation. However, this process makes the calculation in bibliometric becoming less accurate because it doesn’t consider citation quality. There is some studies that proposed a method to measure an inappropriate self-citation, one of them is using self-citation ratio. But, this method doesnt consider topic relatedness between main paper and cited paper. So, its required to determine author’s citation quality to know that author are using anomalous citation based on main paper and each cited paper. This research proposed feature extraction conflict of interest to detect author’s citation quality. It allows us to know how right an author use citation in publication. Two features are proposed in this research. First, conflict of interest feature, is obtained from interest conflict between paper author and citation’s paper author. Second, content similarity feature, is obtained from the similarity between paper and cited papers of author. Deep learning approach is used to get the similarity of each document. Combination of Siamese neural network and Long Short-Term Memory can provide a better result on similarity based on training data. Last, all features will be combined with self-citation’s count feature based on previous research and classified to detect author’s citation quality. Features will be tested for its performance using classification. From the classification results, accuracy will be calculated to obtain the performance of the proposed feature. Based on the result, proposed feature can be used to classify author’s citation quality. It is shown with 66,67% of accuracy by using Random Forest classification and 62% of average accuracy on 3 classifier