Hebrew University of Jerusalem

Displaying 1-27 of 27 results

  • White Papers // Jan 2015

    Scaling Byzantine Fault-Tolerant Replication toWide Area Networks

    During the last few years, there has been considerable progress in the design of Byzantine fault-tolerant replication systems. This paper presents the first hierarchical Byzantine fault-tolerant replication architecture suitable to systems that span multiple wide area sites. The architecture confines the effects of any malicious replica to its local site,...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2014

    How to Design a Job Scheduling Algorithm

    The authors discuss the components of a general approach to design algorithms for resource management in parallel processing systems. Starting from the observation that in this area the average influence of research publications on practical implementations is negligible, they address the three main categories constraints, objectives, and evaluation. For each...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2014

    Experimental Analysis of the Tardiness of Parallel Tasks in Soft Real-Time Systems

    A parallel application is defined as the application that can be executed on multiple processors simultaneously. In software, parallelism is a useful programming technique to take advantage of the hardware advancement in processors manufacturing now-a-days. In real-time systems, where tasks have to respect certain timing constraints during execution, a single...

    Provided By Hebrew University of Jerusalem

  • White Papers // Apr 2013

    On Task Assignment in Data Intensive Scalable Computing

    MapReduce and other data-intensive scalable computing paradigms have emerged as the most popular solution for processing massive data sets, a crucial task in surviving the \"Data deluge\". Recent works have shown that maintaining data locality is paramount to achieve high performance in such paradigms. To this end, suitable task assignment...

    Provided By Hebrew University of Jerusalem

  • White Papers // Apr 2012

    Increased Model-Realism can Make Processor-Selection Easier

    The authors have presented a model for processor selection by parallel job-schedulers that is conceptually simple, easy to understand, and flexible with respect to the kinds of constraints that can be accounted for. The model is also easily extended such that different processor-set and cost-vector definitions can be given for...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2012

    Access-Efficient Balanced Bloom Filters

    The implementation of Bloom Filters in network devices ideally has low memory access-rate and low false positive rate. However, since Bloom Filters hash elements to arbitrary memory blocks, they need high memory access rates. On the other hand, Blocked Bloom Filters first hash elements to a single memory block, where...

    Provided By Hebrew University of Jerusalem

  • White Papers // Aug 2011

    Entrepreneurial Finance Meets Organizational Reality: Comparing Investment Practices And Performance Of Corporate And Independent Venture Capitalists

    This paper investigates the effect of compensation of corporate personnel on their investment in new technologies. The authors focus on a specific corporate activity, namely Corporate Venture Capital (CVC), describing minority equity investment by established-firms in entrepreneurial ventures. The setting offers an opportunity to compare corporate investors to investment experts,...

    Provided By Hebrew University of Jerusalem

  • White Papers // Aug 2011

    Firm Specific And Macro Herding By Professional And Amateur Investors And Their Effects On Market Volatility

    The authors find a herding tendency among both amateur and professional investors and conclude that the propensity to herd is lower in the professionals. These results are obtained both when they consider herding into individual stocks and herding into stocks in general. Herding depends on the firm's systematic risk and...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jul 2011

    The Influence of Doppler Effects in HAP-OFDMA Systems

    The authors consider the impact of Doppler frequency shift on the Orthogonal Frequency Division Multiple Access (OFDMA) signal and Frequency Bank Signal (FBS) transmitted over High Altitude Platforms (HAPs). Theoretical analysis and simulations show that OFDMA systems perform well when the Doppler frequency shift is smaller than 2% of carrier...

    Provided By Hebrew University of Jerusalem

  • White Papers // Feb 2011

    Space-Time Tradeoffs in Software-Based Deep Packet Inspection

    Deep Packet Inspection (DPI) lies at the core of contemporary Network Intrusion Detection/Prevention Systems and Web Application Firewalls. DPI aims to identify various malware (including spam and viruses) by inspecting both the header and the payload of each packet and comparing it to a known set of patterns. DPI is...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2011

    IQ: The Case for Iterative Querying for Knowledge

    Large knowledge bases, the Linked Data cloud, and Web 2.0 communities open up new opportunities for deep question answering to support the advanced information needs of knowledge workers like students, journalists, or business analysts. This calls for going beyond keyword search, towards more expressive ways of entity-relationship-oriented querying with graph...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2011

    Cognitive Authentication Schemes for Unassisted Humans, Safe Against Spyware

    Can the authors secure user authentication against eavesdropping adversaries, relying on human cognitive functions alone, unassisted by any external computational device? To accomplish this goal, they propose challenge response protocols that rely on a shared secret set of pictures. Under the brute-force attack the protocols are safe against eavesdropping, in...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2011

    Two-Dimensional Selections for Feature-Based Data Exchange

    Proper treatment of selections is essential in parametric feature-based design. Data exchange is one of the most important operators in any design paradigm. In this paper, the authors address two-dimensional selections (faces and surfaces) in Feature-Based Data Exchange (FBDE). They define the problem formally and present algorithms to address it,...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2011

    On Synchronization of Wideband Impulsive Systems in Multipath

    A preponderance of ultra-wideband radio communication systems under current study employ the use of Pulse Position Modulation (PPM). However, there are significant issues related to the synchronization of PPM systems in multipath. If the multipath scattering is rich i.e., the number of reflections (paths) increases without bound as the bandwidth...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2011

    Synchronization of PPM Over Wideband Multipath Channels

    The acquisition, or synchronization, of the multi-path profile for ultra-wideband Pulse Position Modulation (PPM) communication systems is considered. The rate of increase of the number of paths (as the bandwidth grows) determines whether synchronization can occur. It is shown that if the number of paths increases without bound, but slower...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2011

    Motion Segmentation Using an Occlusion Detector

    The authors present a novel method for the detection of motion boundaries in a video sequence based on differential properties of the spatio-temporal domain. Regarding the video sequence as a 3D spatio-temporal function, they consider the second moment matrix of its gradients (averaged over a local window), and show that...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2011

    Timing Acquisition of Wideband PPM Systems Over Multipath

    The acquisition, or synchronization, of a multipath channel profile for ultra-wideband Pulse Position Modulation (PPM) communication systems is considered. The rate of increase of the number of paths as the bandwidth grows determines whether acquisition can occur. If the number of independent Gaussian paths increases without bound, but slower than...

    Provided By Hebrew University of Jerusalem

  • White Papers // Oct 2010

    Spatial Dynamics of Indoor Radio Wideband Channels

    The multi-path components of super-wideband (2-17.2GHz) non-line-of-sight channel responses measured inside several buildings are stable along sections that are 27 cm long on average with a standard deviation of 16 cm. The stability regions of multi-path components have an approximately log-normal histogram. An analysis of measured channels that explicitly includes...

    Provided By Hebrew University of Jerusalem

  • White Papers // May 2010

    Tremor Acquisition System Based on UWB Wireless Sensor Network

    This paper suggests quantifying and analyzing tremor using an Ultra Wide-Band (UWB) Wireless Sensor Network (WSN). WSN based on UWB technology provides a new technology for non contact tremor assessment with extremely low radiation and penetration through walls. Tremor is the target symptom in the treatment of many neurological disorders...

    Provided By Hebrew University of Jerusalem

  • White Papers // Apr 2010

    Continuous Close-Proximity RSSI-Based Tracking in Wireless Sensor Networks

    In this paper, the authors develop a continuous high-precision tracking system based on Received Signal Strength Indicator (RSSI) measurements for small ranges. The proposed system uses minimal number of sensor nodes with RSSI capabilities to track a moving object in close-proximity and high transmission rate. The close-proximity enables conversion of...

    Provided By Hebrew University of Jerusalem

  • White Papers // Feb 2010

    The Role Of Incentives In The World Financial Crisis

    A lecture explaining the causes of the 2008-9 world financial crisis in terms of ordinary economic processes. The lecture was delivered at the 39th St. Gallen Symposium, University of St. Gallen, Switzerland, and 8 May 2009. The authors are from the centre not for rationality but for the study of...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2010

    Evaluating Total Order Algorithms in WAN

    Agreed message delivery is an important service in distributed systems, especially when dealing with fault-tolerant applications. This work studies factors influencing protocols that provide global order in Wide Area Networks. Performance evaluation in real network conditions was conducted in order to compare two recently published algorithms. It was found that...

    Provided By Hebrew University of Jerusalem

  • White Papers // Nov 2009

    Leadership Games With Convex Strategy Sets

    A basic model of commitment is to convert a two-player game in strategic form to a "Leadership game" with the same payoffs, where one player, the leader, commits to a strategy, to which the second player always chooses a best reply. This paper studies such leadership games for games with...

    Provided By Hebrew University of Jerusalem

  • White Papers // Aug 2009

    MULAN: Multi-Level Adaptive Network Filter

    A security engine should detect network traffic attacks at line-speed. When an attack is detected, a good security engine should screen away the offending packets and continue to forward all other traffic. Anomaly detection engines must protect the network from new and unknown threats before the vulnerability is discovered and...

    Provided By Hebrew University of Jerusalem

  • White Papers // Apr 2007

    Probabilistic Prediction of Temporal Locality

    The increasing gap between processor and memory speeds, as well as the introduction of multi-core CPUs has exacerbated the dependency of CPU performance on the memory subsystem. This trend motivates the search for more efficient caching mechanisms, enabling both faster service of frequently used blocks and decreased power consumption. In...

    Provided By Hebrew University of Jerusalem

  • White Papers // Apr 2007

    Secretly Monopolizing the CPU Without Superuser Privileges

    The authors describe a \"Cheat\" attack, allowing an ordinary process to hijack any desirable percentage of the CPU cycles without requiring superuser/administrator privileges. Moreover, the nature of the attack is such that, at least in some systems, listing the active processes will erroneously show the cheating process as not using...

    Provided By Hebrew University of Jerusalem

  • White Papers // Mar 2007

    Fine Grained Kernel Logging with KLogger: Experience and Insights

    Understanding the detailed behavior of an operating system is crucial for making informed design decisions. But such an understanding is very hard to achieve, due to the increasing complexity of such systems and the fact that they are implemented and maintained by large and diverse groups of developers. Tools like...

    Provided By Hebrew University of Jerusalem

  • White Papers // Apr 2012

    Increased Model-Realism can Make Processor-Selection Easier

    The authors have presented a model for processor selection by parallel job-schedulers that is conceptually simple, easy to understand, and flexible with respect to the kinds of constraints that can be accounted for. The model is also easily extended such that different processor-set and cost-vector definitions can be given for...

    Provided By Hebrew University of Jerusalem

  • White Papers // Apr 2007

    Secretly Monopolizing the CPU Without Superuser Privileges

    The authors describe a \"Cheat\" attack, allowing an ordinary process to hijack any desirable percentage of the CPU cycles without requiring superuser/administrator privileges. Moreover, the nature of the attack is such that, at least in some systems, listing the active processes will erroneously show the cheating process as not using...

    Provided By Hebrew University of Jerusalem

  • White Papers // Apr 2007

    Probabilistic Prediction of Temporal Locality

    The increasing gap between processor and memory speeds, as well as the introduction of multi-core CPUs has exacerbated the dependency of CPU performance on the memory subsystem. This trend motivates the search for more efficient caching mechanisms, enabling both faster service of frequently used blocks and decreased power consumption. In...

    Provided By Hebrew University of Jerusalem

  • White Papers // Mar 2007

    Fine Grained Kernel Logging with KLogger: Experience and Insights

    Understanding the detailed behavior of an operating system is crucial for making informed design decisions. But such an understanding is very hard to achieve, due to the increasing complexity of such systems and the fact that they are implemented and maintained by large and diverse groups of developers. Tools like...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2015

    Scaling Byzantine Fault-Tolerant Replication toWide Area Networks

    During the last few years, there has been considerable progress in the design of Byzantine fault-tolerant replication systems. This paper presents the first hierarchical Byzantine fault-tolerant replication architecture suitable to systems that span multiple wide area sites. The architecture confines the effects of any malicious replica to its local site,...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2010

    Evaluating Total Order Algorithms in WAN

    Agreed message delivery is an important service in distributed systems, especially when dealing with fault-tolerant applications. This work studies factors influencing protocols that provide global order in Wide Area Networks. Performance evaluation in real network conditions was conducted in order to compare two recently published algorithms. It was found that...

    Provided By Hebrew University of Jerusalem

  • White Papers // Nov 2009

    Leadership Games With Convex Strategy Sets

    A basic model of commitment is to convert a two-player game in strategic form to a "Leadership game" with the same payoffs, where one player, the leader, commits to a strategy, to which the second player always chooses a best reply. This paper studies such leadership games for games with...

    Provided By Hebrew University of Jerusalem

  • White Papers // Feb 2010

    The Role Of Incentives In The World Financial Crisis

    A lecture explaining the causes of the 2008-9 world financial crisis in terms of ordinary economic processes. The lecture was delivered at the 39th St. Gallen Symposium, University of St. Gallen, Switzerland, and 8 May 2009. The authors are from the centre not for rationality but for the study of...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2011

    IQ: The Case for Iterative Querying for Knowledge

    Large knowledge bases, the Linked Data cloud, and Web 2.0 communities open up new opportunities for deep question answering to support the advanced information needs of knowledge workers like students, journalists, or business analysts. This calls for going beyond keyword search, towards more expressive ways of entity-relationship-oriented querying with graph...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2011

    Cognitive Authentication Schemes for Unassisted Humans, Safe Against Spyware

    Can the authors secure user authentication against eavesdropping adversaries, relying on human cognitive functions alone, unassisted by any external computational device? To accomplish this goal, they propose challenge response protocols that rely on a shared secret set of pictures. Under the brute-force attack the protocols are safe against eavesdropping, in...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2011

    Two-Dimensional Selections for Feature-Based Data Exchange

    Proper treatment of selections is essential in parametric feature-based design. Data exchange is one of the most important operators in any design paradigm. In this paper, the authors address two-dimensional selections (faces and surfaces) in Feature-Based Data Exchange (FBDE). They define the problem formally and present algorithms to address it,...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2011

    On Synchronization of Wideband Impulsive Systems in Multipath

    A preponderance of ultra-wideband radio communication systems under current study employ the use of Pulse Position Modulation (PPM). However, there are significant issues related to the synchronization of PPM systems in multipath. If the multipath scattering is rich i.e., the number of reflections (paths) increases without bound as the bandwidth...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2011

    Synchronization of PPM Over Wideband Multipath Channels

    The acquisition, or synchronization, of the multi-path profile for ultra-wideband Pulse Position Modulation (PPM) communication systems is considered. The rate of increase of the number of paths (as the bandwidth grows) determines whether synchronization can occur. It is shown that if the number of paths increases without bound, but slower...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2011

    Motion Segmentation Using an Occlusion Detector

    The authors present a novel method for the detection of motion boundaries in a video sequence based on differential properties of the spatio-temporal domain. Regarding the video sequence as a 3D spatio-temporal function, they consider the second moment matrix of its gradients (averaged over a local window), and show that...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2011

    Timing Acquisition of Wideband PPM Systems Over Multipath

    The acquisition, or synchronization, of a multipath channel profile for ultra-wideband Pulse Position Modulation (PPM) communication systems is considered. The rate of increase of the number of paths as the bandwidth grows determines whether acquisition can occur. If the number of independent Gaussian paths increases without bound, but slower than...

    Provided By Hebrew University of Jerusalem

  • White Papers // Aug 2011

    Entrepreneurial Finance Meets Organizational Reality: Comparing Investment Practices And Performance Of Corporate And Independent Venture Capitalists

    This paper investigates the effect of compensation of corporate personnel on their investment in new technologies. The authors focus on a specific corporate activity, namely Corporate Venture Capital (CVC), describing minority equity investment by established-firms in entrepreneurial ventures. The setting offers an opportunity to compare corporate investors to investment experts,...

    Provided By Hebrew University of Jerusalem

  • White Papers // Aug 2011

    Firm Specific And Macro Herding By Professional And Amateur Investors And Their Effects On Market Volatility

    The authors find a herding tendency among both amateur and professional investors and conclude that the propensity to herd is lower in the professionals. These results are obtained both when they consider herding into individual stocks and herding into stocks in general. Herding depends on the firm's systematic risk and...

    Provided By Hebrew University of Jerusalem

  • White Papers // Aug 2009

    MULAN: Multi-Level Adaptive Network Filter

    A security engine should detect network traffic attacks at line-speed. When an attack is detected, a good security engine should screen away the offending packets and continue to forward all other traffic. Anomaly detection engines must protect the network from new and unknown threats before the vulnerability is discovered and...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jul 2011

    The Influence of Doppler Effects in HAP-OFDMA Systems

    The authors consider the impact of Doppler frequency shift on the Orthogonal Frequency Division Multiple Access (OFDMA) signal and Frequency Bank Signal (FBS) transmitted over High Altitude Platforms (HAPs). Theoretical analysis and simulations show that OFDMA systems perform well when the Doppler frequency shift is smaller than 2% of carrier...

    Provided By Hebrew University of Jerusalem

  • White Papers // May 2010

    Tremor Acquisition System Based on UWB Wireless Sensor Network

    This paper suggests quantifying and analyzing tremor using an Ultra Wide-Band (UWB) Wireless Sensor Network (WSN). WSN based on UWB technology provides a new technology for non contact tremor assessment with extremely low radiation and penetration through walls. Tremor is the target symptom in the treatment of many neurological disorders...

    Provided By Hebrew University of Jerusalem

  • White Papers // Apr 2010

    Continuous Close-Proximity RSSI-Based Tracking in Wireless Sensor Networks

    In this paper, the authors develop a continuous high-precision tracking system based on Received Signal Strength Indicator (RSSI) measurements for small ranges. The proposed system uses minimal number of sensor nodes with RSSI capabilities to track a moving object in close-proximity and high transmission rate. The close-proximity enables conversion of...

    Provided By Hebrew University of Jerusalem

  • White Papers // Oct 2010

    Spatial Dynamics of Indoor Radio Wideband Channels

    The multi-path components of super-wideband (2-17.2GHz) non-line-of-sight channel responses measured inside several buildings are stable along sections that are 27 cm long on average with a standard deviation of 16 cm. The stability regions of multi-path components have an approximately log-normal histogram. An analysis of measured channels that explicitly includes...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2012

    Access-Efficient Balanced Bloom Filters

    The implementation of Bloom Filters in network devices ideally has low memory access-rate and low false positive rate. However, since Bloom Filters hash elements to arbitrary memory blocks, they need high memory access rates. On the other hand, Blocked Bloom Filters first hash elements to a single memory block, where...

    Provided By Hebrew University of Jerusalem

  • White Papers // Feb 2011

    Space-Time Tradeoffs in Software-Based Deep Packet Inspection

    Deep Packet Inspection (DPI) lies at the core of contemporary Network Intrusion Detection/Prevention Systems and Web Application Firewalls. DPI aims to identify various malware (including spam and viruses) by inspecting both the header and the payload of each packet and comparing it to a known set of patterns. DPI is...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2014

    How to Design a Job Scheduling Algorithm

    The authors discuss the components of a general approach to design algorithms for resource management in parallel processing systems. Starting from the observation that in this area the average influence of research publications on practical implementations is negligible, they address the three main categories constraints, objectives, and evaluation. For each...

    Provided By Hebrew University of Jerusalem

  • White Papers // Jan 2014

    Experimental Analysis of the Tardiness of Parallel Tasks in Soft Real-Time Systems

    A parallel application is defined as the application that can be executed on multiple processors simultaneously. In software, parallelism is a useful programming technique to take advantage of the hardware advancement in processors manufacturing now-a-days. In real-time systems, where tasks have to respect certain timing constraints during execution, a single...

    Provided By Hebrew University of Jerusalem

  • White Papers // Apr 2013

    On Task Assignment in Data Intensive Scalable Computing

    MapReduce and other data-intensive scalable computing paradigms have emerged as the most popular solution for processing massive data sets, a crucial task in surviving the \"Data deluge\". Recent works have shown that maintaining data locality is paramount to achieve high performance in such paradigms. To this end, suitable task assignment...

    Provided By Hebrew University of Jerusalem