Resonant harmonic response in tapping-mode atomic force microscopy. Ozgur Sahin * , Calvin F. Qua... more Resonant harmonic response in tapping-mode atomic force microscopy. Ozgur Sahin * , Calvin F. Quate, and Olav Solgaard EL Ginzton Laboratory, Stanford University, Stanford, California 94305, USA. Abdullah Atalar Electrical ...
Torsional harmonic cantilevers allow measurement of time varying tip-sample forces in tapping-mod... more Torsional harmonic cantilevers allow measurement of time varying tip-sample forces in tapping-mode atomic force microscopy. Accuracy of these force measurements is important for quantitative nanomechanical measurements. Here we demonstrate a method to convert the torsional deflection signals into a calibrated force waveform with the use of non-linear dynamical response of the tapping cantilever. Specifically the transitions between steady oscillation regimes are used to calibrate the torsional deflection signals.
Direct time-varying tip-sample force measurements by torsional harmonic cantilevers facilitate de... more Direct time-varying tip-sample force measurements by torsional harmonic cantilevers facilitate detailed investigations of the cantilever dynamics in tapping-mode atomic force microscopy. Here we report experimental evidence that the mathematical relationships describing the steady state dynamics are quantitatively satisfied by the independent measurements of tip-sample forces over a broad range of experimental conditions. These results confirm the existing understanding of the tapping-mode atomic force microscopy and build confidence on the reliability of time-varying tip-sample force measurements by the torsional harmonic cantilevers.
... Search PubMed for. Ozgur Sahin. Open Innovation Challenges. Algorithm to Identify Underlying ... more ... Search PubMed for. Ozgur Sahin. Open Innovation Challenges. Algorithm to Identify Underlying Geometric Features in Noisy 2D Data. Deadline: Sep 19 2011; Reward: $30,000 USD. The Seeker desires an algorithm that can identify ...
In this paper, we describe SPiDeR, a peer-to-peer (P2P) based framework that supports a variety o... more In this paper, we describe SPiDeR, a peer-to-peer (P2P) based framework that supports a variety of Web service discovery operations. SPiDeR organizes the service providers into a structured P2P overlay and allows them to advertise and lookup services in a completely decentralized and dynamic manner. It supports three different kinds of search operations: For advertising and locating services, service providers can use keywords extracted from service descriptions (keyword-based search), categories from a global ontology (ontology-based search), and/or paths from the service automaton (behavior-based search). The users can also rate the quality of the services they use. The ratings are accumulated within the system so that users can query for the quality ratings of the discovered services. Finally, we present the performance of SPiDeR in terms of routing using a simulator.
Similarity search in textual databases and bioinformatics has received substantial attention in t... more Similarity search in textual databases and bioinformatics has received substantial attention in the past decade. Numerous filtration and indexing techniques have been proposed to reduce the curse of dimensionality. This paper proposes a novel approach to map the problem of whole-genome sequence homology search into an approximate vector comparison in the well-established multidimensional vector space. We propose the application of
Peer-to-peer systems are mainly used for object shar-ing although they can provide the infrastruc... more Peer-to-peer systems are mainly used for object shar-ing although they can provide the infrastructure for many other applications. In this paper, we extend the idea of ob-ject sharing to data sharing on a peer-to-peer system. We propose a method, which is based on the multidimensional ...
A Peer-to-Peer Framework for Web Service Discovery with Ranking * Fatih Emekci Ozgur D. Sahin Div... more A Peer-to-Peer Framework for Web Service Discovery with Ranking * Fatih Emekci Ozgur D. Sahin Divyakant Agrawal Amr El Abbadi Department of Computer Science University of California Santa Barbara, CA 93106, USA {fatih,odsahin,agrawal,amr}@cs.ucsb.edu Abstract ...
Structured P2P systems are effective for exact key searches in a distributed environment as they ... more Structured P2P systems are effective for exact key searches in a distributed environment as they offer scalability, self-organization, and dynamicity. These valuable properties also make them a candidate for more complex queries, such as range queries. In this paper, we describe PRoBe, a system that supports range queries over multiple attributes in P2P networks. PRoBe uses a multi-dimensional logical space for this purpose and maps data items onto this space based on their attribute values. The logical space is divided into hyper-rectangles, each maintained by a peer in the system. The range queries correspond to hyper-rectangles which are answered by forwarding the query to the peers responsible for overlapping regions of the logical space. We also propose load balancing techniques and show how cached query answers can be utilized for the efficient evaluation of similar range queries. The performance of PRoBe and the effects of various parameters are analyzed through a simulation study.
Peer-to-peer applications are used to share large volumes of data. An important requirement of th... more Peer-to-peer applications are used to share large volumes of data. An important requirement of these systems is efficient methods for locating the data of interest in a large collection of data. Unfortunately current peer-to-peer systems either offer exact keyword match functionality or provide inefficient text search methods through centralized indexing or flooding. In this paper we propose a method based on popular Information Retrieval techniques to facilitate content-based searches in peer-to-peer systems. A simulation of the proposed design was implemented and its performance was evaluated using some commonly used test collections, including Ohsumed which was used for the TREC-9 Filtering Track. The experiments demonstrate that our approach is scalable as it achieves high recall by visiting only a small subset of the peers.
Publish/Subscribe systems have become a prevalent model for delivering data from producers (publi... more Publish/Subscribe systems have become a prevalent model for delivering data from producers (publishers) to consumers (subscribers) distributed across wide-area networks while decoupling the publishers and the subscribers from each other. In this paper we present Meghdoot, which adapts content-based publish/subscribe systems to Distributed Hash Table based P2P networks in order to provide scalable content delivery mechanisms while maintaining the decoupling between the publishers and the subscribers. Meghdoot is designed to adapt to highly skewed data sets, which is typical of real applications. The experimental results demonstrate that Meghdoot balances the load among the peers and the design scales well with increasing number of peers, subscriptions and events.
As a distributed hash table (DHT), a content addressable network (CAN) provides efficient routing... more As a distributed hash table (DHT), a content addressable network (CAN) provides efficient routing and object location in a decentralized manner while offering fault tolerance and dynamic peer operations. However, as opposed to other DHTs that use a flat ID space, CAN uses a multi-dimensional logical space. DHTs usually require O(logN) routing information per peer and provide routing in O(logN) hops, where N is the number of peers in the system. In CAN, on the other hand, each peer keeps only constant amount of routing information and the routing takes O(dN1d/) hops, where d is the dimensionality of the logical space. Hence the routing performance of CAN is worse than other DHTs especially when d is small. In this paper, we describe and evaluate several schemes for efficient routing in CAN by keeping additional routing information at the peers. Furthermore, due to the underlying multidimensional ID space, CAN is used by applications that require content-based mapping of data objects onto the ID space. Since uniform hashing is not used, such mappings introduce skewed object distributions among the peers. Thus we also describe load balancing schemes for CAN and investigate their efficiency.
... Vaidya and Clifton [33] studied privacy preserving distributed association rule mining over v... more ... Vaidya and Clifton [33] studied privacy preserving distributed association rule mining over vertically partitioned data and Kantarcioglu and Clifton [22] studied the privacy preserving association rule mining over horizontally partitioned data using cryptographic tools such as ...
A Peer-to-Peer Framework for Web Service Discovery with Ranking * Fatih Emekci Ozgur D. Sahin Div... more A Peer-to-Peer Framework for Web Service Discovery with Ranking * Fatih Emekci Ozgur D. Sahin Divyakant Agrawal Amr El Abbadi Department of Computer Science University of California Santa Barbara, CA 93106, USA {fatih,odsahin,agrawal,amr}@cs.ucsb.edu Abstract ...
... Permission to make digital or hard copies of all or part of this work for personal or classro... more ... Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. ...
Resonant harmonic response in tapping-mode atomic force microscopy. Ozgur Sahin * , Calvin F. Qua... more Resonant harmonic response in tapping-mode atomic force microscopy. Ozgur Sahin * , Calvin F. Quate, and Olav Solgaard EL Ginzton Laboratory, Stanford University, Stanford, California 94305, USA. Abdullah Atalar Electrical ...
Torsional harmonic cantilevers allow measurement of time varying tip-sample forces in tapping-mod... more Torsional harmonic cantilevers allow measurement of time varying tip-sample forces in tapping-mode atomic force microscopy. Accuracy of these force measurements is important for quantitative nanomechanical measurements. Here we demonstrate a method to convert the torsional deflection signals into a calibrated force waveform with the use of non-linear dynamical response of the tapping cantilever. Specifically the transitions between steady oscillation regimes are used to calibrate the torsional deflection signals.
Direct time-varying tip-sample force measurements by torsional harmonic cantilevers facilitate de... more Direct time-varying tip-sample force measurements by torsional harmonic cantilevers facilitate detailed investigations of the cantilever dynamics in tapping-mode atomic force microscopy. Here we report experimental evidence that the mathematical relationships describing the steady state dynamics are quantitatively satisfied by the independent measurements of tip-sample forces over a broad range of experimental conditions. These results confirm the existing understanding of the tapping-mode atomic force microscopy and build confidence on the reliability of time-varying tip-sample force measurements by the torsional harmonic cantilevers.
... Search PubMed for. Ozgur Sahin. Open Innovation Challenges. Algorithm to Identify Underlying ... more ... Search PubMed for. Ozgur Sahin. Open Innovation Challenges. Algorithm to Identify Underlying Geometric Features in Noisy 2D Data. Deadline: Sep 19 2011; Reward: $30,000 USD. The Seeker desires an algorithm that can identify ...
In this paper, we describe SPiDeR, a peer-to-peer (P2P) based framework that supports a variety o... more In this paper, we describe SPiDeR, a peer-to-peer (P2P) based framework that supports a variety of Web service discovery operations. SPiDeR organizes the service providers into a structured P2P overlay and allows them to advertise and lookup services in a completely decentralized and dynamic manner. It supports three different kinds of search operations: For advertising and locating services, service providers can use keywords extracted from service descriptions (keyword-based search), categories from a global ontology (ontology-based search), and/or paths from the service automaton (behavior-based search). The users can also rate the quality of the services they use. The ratings are accumulated within the system so that users can query for the quality ratings of the discovered services. Finally, we present the performance of SPiDeR in terms of routing using a simulator.
Similarity search in textual databases and bioinformatics has received substantial attention in t... more Similarity search in textual databases and bioinformatics has received substantial attention in the past decade. Numerous filtration and indexing techniques have been proposed to reduce the curse of dimensionality. This paper proposes a novel approach to map the problem of whole-genome sequence homology search into an approximate vector comparison in the well-established multidimensional vector space. We propose the application of
Peer-to-peer systems are mainly used for object shar-ing although they can provide the infrastruc... more Peer-to-peer systems are mainly used for object shar-ing although they can provide the infrastructure for many other applications. In this paper, we extend the idea of ob-ject sharing to data sharing on a peer-to-peer system. We propose a method, which is based on the multidimensional ...
A Peer-to-Peer Framework for Web Service Discovery with Ranking * Fatih Emekci Ozgur D. Sahin Div... more A Peer-to-Peer Framework for Web Service Discovery with Ranking * Fatih Emekci Ozgur D. Sahin Divyakant Agrawal Amr El Abbadi Department of Computer Science University of California Santa Barbara, CA 93106, USA {fatih,odsahin,agrawal,amr}@cs.ucsb.edu Abstract ...
Structured P2P systems are effective for exact key searches in a distributed environment as they ... more Structured P2P systems are effective for exact key searches in a distributed environment as they offer scalability, self-organization, and dynamicity. These valuable properties also make them a candidate for more complex queries, such as range queries. In this paper, we describe PRoBe, a system that supports range queries over multiple attributes in P2P networks. PRoBe uses a multi-dimensional logical space for this purpose and maps data items onto this space based on their attribute values. The logical space is divided into hyper-rectangles, each maintained by a peer in the system. The range queries correspond to hyper-rectangles which are answered by forwarding the query to the peers responsible for overlapping regions of the logical space. We also propose load balancing techniques and show how cached query answers can be utilized for the efficient evaluation of similar range queries. The performance of PRoBe and the effects of various parameters are analyzed through a simulation study.
Peer-to-peer applications are used to share large volumes of data. An important requirement of th... more Peer-to-peer applications are used to share large volumes of data. An important requirement of these systems is efficient methods for locating the data of interest in a large collection of data. Unfortunately current peer-to-peer systems either offer exact keyword match functionality or provide inefficient text search methods through centralized indexing or flooding. In this paper we propose a method based on popular Information Retrieval techniques to facilitate content-based searches in peer-to-peer systems. A simulation of the proposed design was implemented and its performance was evaluated using some commonly used test collections, including Ohsumed which was used for the TREC-9 Filtering Track. The experiments demonstrate that our approach is scalable as it achieves high recall by visiting only a small subset of the peers.
Publish/Subscribe systems have become a prevalent model for delivering data from producers (publi... more Publish/Subscribe systems have become a prevalent model for delivering data from producers (publishers) to consumers (subscribers) distributed across wide-area networks while decoupling the publishers and the subscribers from each other. In this paper we present Meghdoot, which adapts content-based publish/subscribe systems to Distributed Hash Table based P2P networks in order to provide scalable content delivery mechanisms while maintaining the decoupling between the publishers and the subscribers. Meghdoot is designed to adapt to highly skewed data sets, which is typical of real applications. The experimental results demonstrate that Meghdoot balances the load among the peers and the design scales well with increasing number of peers, subscriptions and events.
As a distributed hash table (DHT), a content addressable network (CAN) provides efficient routing... more As a distributed hash table (DHT), a content addressable network (CAN) provides efficient routing and object location in a decentralized manner while offering fault tolerance and dynamic peer operations. However, as opposed to other DHTs that use a flat ID space, CAN uses a multi-dimensional logical space. DHTs usually require O(logN) routing information per peer and provide routing in O(logN) hops, where N is the number of peers in the system. In CAN, on the other hand, each peer keeps only constant amount of routing information and the routing takes O(dN1d/) hops, where d is the dimensionality of the logical space. Hence the routing performance of CAN is worse than other DHTs especially when d is small. In this paper, we describe and evaluate several schemes for efficient routing in CAN by keeping additional routing information at the peers. Furthermore, due to the underlying multidimensional ID space, CAN is used by applications that require content-based mapping of data objects onto the ID space. Since uniform hashing is not used, such mappings introduce skewed object distributions among the peers. Thus we also describe load balancing schemes for CAN and investigate their efficiency.
... Vaidya and Clifton [33] studied privacy preserving distributed association rule mining over v... more ... Vaidya and Clifton [33] studied privacy preserving distributed association rule mining over vertically partitioned data and Kantarcioglu and Clifton [22] studied the privacy preserving association rule mining over horizontally partitioned data using cryptographic tools such as ...
A Peer-to-Peer Framework for Web Service Discovery with Ranking * Fatih Emekci Ozgur D. Sahin Div... more A Peer-to-Peer Framework for Web Service Discovery with Ranking * Fatih Emekci Ozgur D. Sahin Divyakant Agrawal Amr El Abbadi Department of Computer Science University of California Santa Barbara, CA 93106, USA {fatih,odsahin,agrawal,amr}@cs.ucsb.edu Abstract ...
... Permission to make digital or hard copies of all or part of this work for personal or classro... more ... Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. ...
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