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- Title
- Scheduling for CPU Packing and node shutdown to reduce the energy consumption of high performance computing centers
- Creator
- Vudayagiri, Srikanth Phani
- Date
- 2010
- Collection
- Electronic Theses & Dissertations
- Description
-
During the past decade, there has been a tremendous growth in the high performance computing and data center arenas. The huge energy requirements in these sectors have prompted researchers to investigate possible ways to reduce their energy consumption. Reducing the energy consumption is not only beneficial to an organization economically but also to the environment. In this thesis, we focus our attention on high performance scientific computing clusters. We first perform experiments with the...
Show moreDuring the past decade, there has been a tremendous growth in the high performance computing and data center arenas. The huge energy requirements in these sectors have prompted researchers to investigate possible ways to reduce their energy consumption. Reducing the energy consumption is not only beneficial to an organization economically but also to the environment. In this thesis, we focus our attention on high performance scientific computing clusters. We first perform experiments with the CPU Packing feature available in Linux using programs from the SPEC CPU2000 suite. We then look at an energy-aware scheduling algorithm for the cluster that assumes that CPU Packing is enabled on all the nodes. Using simulations, we compare the scheduling done by this algorithm to that done by the existing, commercial Moab scheduler in the cluster. We experiment with the Moab Green Computing feature and based on our observations, we implement the shutdown mechanism used by Moab in our simulations. Our results show that Moab Green Computing could provide about an 13% energy savings on average for the HPC cluster without any noticeable decrease in the performance of jobs.
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- Title
- Faster algorithms for machine learning problems in high dimension
- Creator
- Ye, Mingquan
- Date
- 2019
- Collection
- Electronic Theses & Dissertations
- Description
-
"When dealing with datasets with high dimension, the existing machine learning algorithms often do not work in practice. Actually, most of the real-world data has the nature of low intrinsic dimension. For example, data often lies on a low-dimensional manifold or has a low doubling dimension. Inspired by this phenomenon, this thesis tries to improve the time complexities of two fundamental problems in machine learning using some techniques in computational geometry. In Chapter two, we propose...
Show more"When dealing with datasets with high dimension, the existing machine learning algorithms often do not work in practice. Actually, most of the real-world data has the nature of low intrinsic dimension. For example, data often lies on a low-dimensional manifold or has a low doubling dimension. Inspired by this phenomenon, this thesis tries to improve the time complexities of two fundamental problems in machine learning using some techniques in computational geometry. In Chapter two, we propose a bi-criteria approximation algorithm for minimum enclosing ball with outliers and extend it to the outlier recognition problem. By virtue of the "core-set" idea and the Random Gradient Descent Tree, we propose an efficient algorithm which is linear in the number of points n and the dimensionality d, and provides a probability bound. In experiments, compared with some existing outlier recognition algorithms, our method is proven to be efficient and robust to the outlier ratios. In Chapter three, we adopt the "doubling dimension" to characterize the intrinsic dimension of a point set. By the property of doubling dimension, we can approximate the geometric alignment between two point sets by executing the existing alignment algorithms on their subsets, which achieves a much smaller time complexity. More importantly, the proposed approximate method has a theoretical upper bound and can serve as the preprocessing step of any alignment algorithm."--Page ii.
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- Title
- Formalization and verification of property specification patterns
- Creator
- Bryndin, Dmitriy
- Date
- 2010
- Collection
- Electronic Theses & Dissertations
- Description
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Finite-state verification (FSV) techniques are intended for proving properties of software systems. Although significant progress has been made in the last decade automating FSV techniques, the adoption of these techniques by software developers is low. The Specification Pattern System (SPS) is intended to assist users in creating such specifications. It identifies common specification patterns and indicates how to translate the patterns into a variety of different specification languages....
Show moreFinite-state verification (FSV) techniques are intended for proving properties of software systems. Although significant progress has been made in the last decade automating FSV techniques, the adoption of these techniques by software developers is low. The Specification Pattern System (SPS) is intended to assist users in creating such specifications. It identifies common specification patterns and indicates how to translate the patterns into a variety of different specification languages. However, the patterns in the SPS are defined informally and their translations are not verified. This work discusses the informal nature of these definitions, proposes a formalization for them and provides formal proofs for the translation of patterns to Linear Temporal Logic.
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- Title
- A study of Bluetooth Frequency Hopping sequence : modeling and a practical attack
- Creator
- Albazrqaoe, Wahhab
- Date
- 2011
- Collection
- Electronic Theses & Dissertations
- Description
-
The Bluetooth is a wireless interface that enables electronic devices to establish short-range, ad-hoc wireless connections. This kind of short-range wireless networking is known as Wireless Personal Area Networks (WPAN). Because of its attractive features of small size, low cost, and low power, Bluetooth gains a world wide usage. It is embedded in many portable computing devices and considered as a good replacement for local wire connections. Since wireless data is inherently exposed to...
Show moreThe Bluetooth is a wireless interface that enables electronic devices to establish short-range, ad-hoc wireless connections. This kind of short-range wireless networking is known as Wireless Personal Area Networks (WPAN). Because of its attractive features of small size, low cost, and low power, Bluetooth gains a world wide usage. It is embedded in many portable computing devices and considered as a good replacement for local wire connections. Since wireless data is inherently exposed to eavesdropping, the security and confidentiality is a central issue for wireless standard as well as Bluetooth. To maintain security and confidentiality of wireless packets, the Bluetooth system mainly relies on the Frequency Hopping mechanism to equivocate an adversary. By this technique, a wireless channel is accessed for transmitting a packet. For each wireless packet, a single channel is selected in a pseudo random way. This kind of randomness in channel selection makes it difficult for an eavesdropped to predict the next channel to be accessed. Hence, capturing Bluetooth wireless packets is a challenge. In this work, we investigate the Frequency Hopping sequence and specifically the hop selection kernel. We analyze the operation of the kernel hardware by partitioning it into three parts. Based on this modeling, we propose an attacking method for the hop selection kernel. The proposed method shows how to expose the clock value hidden in the kernel. This helps to predict Bluetooth hopping sequence and, hence, capturing Bluetooth wireless packet is possible.
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