ppxscal/embedding_network huggingface dataset:
On the choice of transforms for data hiding in compressed video
Authors: M. Ramkumar
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 1999. on 1999 IEEE International Conference - Volume 06 (1999)

We present an information-theoretic approach to obtain an estimate of the number of bits that can be hidden in compressed image sequences. We show how addition of the message signal in a suitable transform domain rather than the spatial domain can significantly increase the data hiding capacity. We compare the data hiding capacities achievable with different block transforms and show that the choice of the transform should depend on the robustness needed. While it is better to choose transforms with good energy compaction property (like DCT, wavelet etc.) when the robustness required is low, transforms with poorer energy compaction property (like the Hadamard or Hartley transform) are preferable choices for higher robustness requirements.
Storage alternatives for mobile computers
Authors: Fred Douglis, Ramón Cáceres, Frans Kaashoek, Kai Li, Brian Marsh, Joshua A. Tauber
Venue: Proceedings of the 1st USENIX conference on Operating Systems Design and Implementation (1994)

Mobile computers such as notebooks, subnotebooks, and palmtops require low weight, low power consumption, and good interactive performance. These requirements impose many challenges on architectures and operating systems. This paper investigates three alternative storage devices for mobile computers: magnetic hard disks, flash memory disk emulators, and flash memory cards. We have used hardware measurements and trace-driven simulation to evaluate each of the alternative storage devices and their related design strategies. Hardware measurements on an HP OmniBook 300 highlight differences in the performance of the three devices as used on the Omnibook, especially the poor performance of version 2.00 of the Microsoft Flash File System [11] when accessing large files. The traces used in our study came from different environments, including mobile computers (Macintosh Power-Books) and desktop computers (running Windows or HPUX), as well as synthetic workloads. Our simulation study shows that flash memory can reduce energy consumption by an order of magnitude, compared to magnetic disk, while providing good read performance and acceptable write performance. These energy savings can translate into a 22% extension of battery life. We also find that the amount of unused memory in a flash memory card has a substantial impact on energy consumption, performance, and endurance: compared to low storage utilizations (40% full), running flash memory near its capacity (95% full) can increase energy consumption by 70-190%, degrade write response time by 30%, and decrease the lifetime of the memory card by up to a third. For flash disks, asynchronous erasure can improve write response time by a factor of 2.5.
A study in Malloc: a case of excessive minor faults
Authors: Phillip Ezolt
Venue: Proceedings of the 5th annual Linux Showcase & Conference - Volume 5 (2001)

GNU libc's default setting for malloc can cause a significant performance penalty for applications that use it extensively, such as Compaq's high performance extended math library, CXML. The default malloc tuning can cause a significant number of minor page faults, and result in application performance of only half of the true potential. This paper describes how to remove the performance penalty using environmental variables and the method used to discover the cause of the malloc performance penalty.
A Fair Benchmark for Evaluating the Latent Potential of Heterogeneous Coupled Clusters
Authors: Carsten Clauss, Stephan Gsell, Stefan Lankes, Thomas Bemmerl
Venue: Proceedings of the Sixth International Symposium on Parallel and Distributed Computing (2007)

Coupled clusters usually exhibit a heterogeneous but also hierarchical structure in terms of communication and computation. Therefore, it is inevitable to adapt parallel applications to such systems in order to gain reasonable performance results. Moreover, also regular benchmark tools are not capable of exposing the latent potential of such coupled cluster systems. Though without adapted (or better self-adapting) benchmark tools for such systems, it is almost not possible to forecast the scalability of well-adapted applications and one is not able to compare the possibly achievable performance in an application independent manner. In this paper we present such a fair, selfadapting and meaningful benchmark tool for heterogeneous coupled cluster systems, following the MPI standard.
Reducing downtime due to system maintenance and upgrades
Authors: Shaya Potter, Jason Nieh
Venue: Proceedings of the 19th conference on Large Installation System Administration Conference - Volume 19 (2005)

Patching, upgrading, and maintaining operating system software is a growing management complexity problem that can result in unacceptable system downtime. We introduce AutoPod, a system that enables unscheduled operating system updates while preserving application service availability. AutoPod provides a group of processes and associated users with an isolated machine-independent virtualized environment that is decoupled from the underlying operating system instance. This virtualized environment is integrated with a novel checkpoint-restart mechanism which allows processes to be suspended, resumed, and migrated across operating system kernel versions with different security and maintenance patches. AutoPod incorporates a system status service to determine when operating system patches need to be applied to the current host, then automatically migrates application services to another host to preserve their availability while the current host is updated and rebooted. We have implemented AutoPod on Linux without requiring any application or operating system kernel changes. Our measurements on real world desktop and server applications demonstrate that AutoPod imposes little overhead and provides sub-second suspend and resume times that can be an order of magnitude faster than starting applications after a system reboot. AutoPod enables systems to autonomically stay updated with relevant maintenance and security patches, while ensuring no loss of data and minimizing service disruption.
Localized Outlying and Boundary Data Detection in Sensor Networks
Authors: Weili Wu, Xiuzhen Cheng, Min Ding, Kai Xing, Fang Liu, Ping Deng
Venue: IEEE Transactions on Knowledge and Data Engineering (2007)

This paper targets the identification of outlying sensors (that is, outlying reading sensors) and the detection of the reach of events in sensor networks. Typical applications include the detection of the transportation front line of some vegetation or animalcule's growth over a certain geographical region. We propose and analyze two novel algorithms for outlying sensor identification and event boundary detection. These algorithms are purely localized and, thus, scale well to large sensor networks. Their computational overhead is low, since only simple numerical operations are involved. Simulation results indicate that these algorithms can clearly detect the event boundary and can identify outlying sensors with a high accuracy and a low false alarm rate when as many as 20 percent sensors report outlying readings. Our work is exploratory in that the proposed algorithms can accept any kind of scalar values as inputs—a dramatic improvement over existing work, which takes only 0/1 decision predicates. Therefore, our algorithms are generic. They can be applied as long as "events” can be modeled by numerical numbers. Though designed for sensor networks, our algorithms can be applied to the outlier detection and regional data analysis in spatial data mining.
Dirichlet aggregation: unsupervised learning towards an optimal metric for proportional data
Authors: Hua-Yan Wang, Hongbin Zha, Hong Qin
Venue: Proceedings of the 24th international conference on Machine learning (2007)

Proportional data (normalized histograms) have been frequently occurring in various areas, and they could be mathematically abstracted as points residing in a geometric simplex. A proper distance metric on this simplex is of importance in many applications including classification and information retrieval. In this paper, we develop a novel framework to learn an optimal metric on the simplex. Major features of our approach include: 1) its flexibility to handle correlations among bins/dimensions; 2) widespread applicability without being limited to ad hoc backgrounds; and 3) a "real" global solution in contrast to existing traditional local approaches. The technical essence of our approach is to fit a parametric distribution to the observed empirical data in the simplex. The distribution is parameterized by affinities between simplex vertices, which is learned via maximizing likelihood of observed data. Then, these affinities induce a metric on the simplex, defined as the earth mover's distance equipped with ground distances derived from simplex vertex affinities.
Automatic snakes for robust lip boundaries extraction
Authors: P. Delmas
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 1999. on 1999 IEEE International Conference - Volume 06 (1999)

Active contours or snakes are widely used in object segmentation for their ability to integrate feature extraction and pixel candidate linking in a single energy minimizing process. But the sensitivity to parameters values and initialization is also a widely known problem. The performance of snakes can be enhanced by better initialization close to the desired solution. We present a fine mouth region of interest (ROI) extraction using gray level image and corresponding gradient information. We link this technique with an original snake method. The automatic snakes use spatially varying coefficients to remain along its evolution in a mouth-like shape. Our experimentations on a large image database prove its robustness regarding speakers change of the ROI mouth extraction and automatic snakes algorithms. The main application of our algorithms is video-conferencing.
False Qubits?: Polarization of Light and Josephson Junction
Authors: Robert Alicki
Venue: Open Systems Information Dynamics (2007)

We compare two physical systems: polarization degrees of freedom of a macroscopic light beam and the Josephson junction (JJ) in the "charge qubit regime". The first system obviously cannot carry genuine quantum information and we show that the maximal entanglement which could be encoded into polarization of two light beams scales like 1/(photon number). Two theories of JJ, one leading to the picture of "JJ-qubit" and the other based on the mean-field approach are discussed. The later, which seems to be more appropriate, implies that the JJ system is, essentially, mathematically equivalent to the polarization of a light beam with the number of photons replaced by the number of Cooper pairs. The existing experiments consistent with the "JJ-qubit" picture and the theoretical arguments supporting, on the contrary, the classical model are briefly discussed. The Franck-Hertz-type experiment is suggested as an ultimate test of the JJ nature.
The Cramer-Rao bound for the estimation of noisy phase signals
Authors: A. M. Zoubir
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 2001. on IEEE International Conference - Volume 05 (2001)

This paper deals with noisy phase monocomponent signals in additive noise. This model is more appropriate for real world applications in particular for radar and communications. The problem is introduced and a maximum likelihood solution is proposed. Specifically, the Cramer-Rao bound is explicitly derived and compared to the case of noise free phase.
Using Iprobe to optimize Apache on Alpha/Linux
Authors: Phillip Ezolt
Venue: Proceedings of the 3rd annual conference on Atlanta Linux Showcase - Volume 3 (1999)

This Paper describes how Iprobe, an Alpha/Linux performance tool, was used to find system performance bottlenecks while running the Apache web server on Alpha/Linux. It describes the kernel bottlenecks uncovered, and possible solutions.
Designing controllable computer systems
Authors: Christos Karamanolis, Magnus Karlsson, Xiaoyun Zhu
Venue: Proceedings of the 10th conference on Hot Topics in Operating Systems - Volume 10 (2005)

Adaptive control theory is emerging as a viable approach for the design of self-managed computer systems. This paper argues that the systems community should not be concerned with the design of adaptive controllers--there are off-the-shelf controllers that can be used to tune any system that abides by certain properties. Systems research should instead be focusing on the open problem of designing and configuring systems that are amenable to dynamic, feedback-based control. Currently, there is no systematic approach for doing this. To that aim, this paper introduces a set of properties derived from control theory that controllable computer systems should satisfy. We discuss the intuition behind these properties and the challenges to be addressed by system designers trying to enforce them. For the discussion, we use two examples of management problems: 1) a dynamically controlled scheduler that enforces performance goals in a 3-tier system; 2) a system where we control the number of blades assigned to a workload to meet performance goals within power budgets.
High-speed CORDIC implementations using advanced circuit techniques
Authors: Gunok Jung
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 200. on IEEE International Conference - Volume 02 (2001)

Presents results on using advanced domino circuit design techniques to implement a CORDIC processor. Skew-tolerant domino, enhanced precharged contention, nonblocking domino and pulsed reset domino circuit techniques are explained and applied to the implementation of this functional unit. For comparison purposes, a baseline design using standard two-phase domino with intermediate latches is also developed. Simulation results show that significant throughput improvement is possible using the advanced circuit techniques, with the pulsed reset style having the highest speed. On the other hand, these approaches result in increased power dissipation.
Using the Structured-case Approach to Build Theory in E-Government
Authors: Rene Riedl, Friedrich Roithmayr, Bernhard Schenkenfelder
Venue: Proceedings of the 40th Annual Hawaii International Conference on System Sciences (2007)

Both from the perspective of practitioners as well as from an academic point of view, e-government has gained considerable momentum in the past years. However, in order to create a sound e-government body of knowledge much research work still has to be done. This paper reports on the findings of the use of the structured-case approach to investigate the success factors for e-government initiatives. A total of fifteen case studies were conducted in seven European countries. The paper outlines the contribution of the structured-case approach to build e-government theories. The paper concludes that the structured-case approach demonstrates the process of knowledge and theory building because it clearly points out the linkage between the data collected and the conclusions drawn. Hence, the application of the structured-case approach assures scientific rigor-an element that is often missed or done poorly in IS case study research.
Botz-4-sale: surviving organized DDoS attacks that mimic flash crowds
Authors: Srikanth Kandula, Dina Katabi, Matthias Jacob, Arthur Berger
Venue: Proceedings of the 2nd conference on Symposium on Networked Systems Design & Implementation - Volume 2 (2005)

Recent denial of service attacks are mounted by professionals using Botnets of tens of thousands of compromised machines. To circumvent detection, attackers are increasingly moving away from bandwidth floods to attacks that mimic the Web browsing behavior of a large number of clients, and target expensive higher-layer resources such as CPU, database and disk bandwidth. The resulting attacks are hard to defend against using standard techniques, as the malicious requests differ from the legitimate ones in intent but not in content. We present the design and implementation of Kill-Bots, a kernel extension to protect Web servers against DDoS attacks that masquerade as flash crowds. Kill-Bots provides authentication using graphical tests but is different from other systems that use graphical tests. First, Kill-Bots uses an intermediate stage to identify the IP addresses that ignore the test, and persistently bombard the server with requests despite repeated failures at solving the tests. These machines are bots because their intent is to congest the server. Once these machines are identified, Kill-Bots blocks their requests, turns the graphical tests off, and allows access to legitimate users who are unable or unwilling to solve graphical tests. Second, Kill-Bots sends a test and checks the client's answer without allowing unauthenticated clients access to sockets, TCBs, and worker processes. Thus, it protects the authentication mechanism from being DDoSed. Third, Kill-Bots combines authentication with admission control. As a result, it improves performance, regardless of whether the server overload is caused by DDoS or a true Flash Crowd.
DIGITAL FX!32 running 32-bit ×86 applications on alpha NT
Authors: Anton Chernoff, Ray Hookway
Venue: Proceedings of the USENIX Windows NT Workshop on The USENIX Windows NT Workshop 1997 (1997)

DIGITAL FX!32 is a unique combination of emulation and binary translation which makes it so that any 32-bit program that runs on an x86 system running Windows NT 4.0 will install and run on an Alpha Windows NT 4.0 system. After translation, x86 applications run as fast under DIGITAL FX!32 on a 500Mz Alpha system as on a 200Mz Pentium-Pro. The emulator and its associated runtime provide for transparent execution of x86 applications. The emulator uses translation results when they are available and produces profile data for use by the translator. The translator provides native Alpha code for the portions of an x86 application which have been previously executed. A server manages the translation process for the user, making the overall process completely transparent. This paper focuses on the ways in which DIGITAL FX!32 achieves its transparency when running on an unmodified NT system.
Thresher: an efficient storage manager for copy-on-write snapshots
Authors: Liuba Shrira, Hao Xu
Venue: Proceedings of the annual conference on USENIX '06 Annual Technical Conference (2006)

A new generation of storage systems exploit decreasing storage costs to allow applications to take snapshots of past states and retain them for long durations. Over time, current snapshot techniques can produce large volumes of snapshots. Indiscriminately keeping all snapshots accessible is impractical, even if raw disk storage is cheap, because administering such large-volume storage is expensive over a long duration. Moreover, not all snapshots are equally valuable. Thresher is a new snapshot storage management system, based on novel copy-on-write snapshot techniques, that is the first to provide applications the ability to discriminate among snapshots efficiently. Valuable snapshots can remain accessible or stored with faster access while less valuable snapshots are discarded or moved off-line. Measurements of the Thresher prototype indicate that the new techniques are efficient and scalable, imposing minimal (4%) performance penalty on expected common workloads.
Optics in Computer Architectures: Basis of WDM, Technologies and Potentials
Authors: Y. Wang, T. Kusserrow, S. Irmer, A. Hasse, M. Bartels, N. Dharmarasu, H. Hillmer
Venue: Proceedings of the Second International Conference on Systems (2007)

We present novel concepts, technologies and potentials of optical data communication, especially for future computer architectures. The WDM (wavelength division multiplexing) and the optical wiring technologies are explained in detail. Experimental results of tunable optical filters, which play a major role in WDM systems, are reported. New concepts for novel optical interconnectors and novel miniaturized lasers for direct generation of green light are proposed as examples for possible next generation components to improve the performance of optical communication based computer architecture.
Alleviating problems due to resource constraints in computer networks using additional information
Authors: Jogesh K. Muppala
Venue:  (2006)

Motivated and driven by the development of real-time multimedia applications, Quality of Service (QoS) has been a hot research area in computer networks for quite a long time. However, providing QoS in computer networks always faces network resource constraints: bandwidth, delay, and etc. Therefore, in this thesis, we try to alleviate these problems using additional information. The objective of the online QoS routing problem is to minimize the call blocking probability due to insufficient network resources while supporting the required quality of service. A scheme is proposed to protect those critical links/paths that are crucial for future requests. In this problem, the network resource constraint is the limited network routing ability and the information we made use of is the co-relationship among the network paths/links which can reflect link criticality. The second problem is the provisioning problem with enhanced Hose model in Virtual Private Networks (VPN). We enhanced the hose model specification to support delay requirements at the VPN endpoints. In this problem, the network resource constraint is the limited link bandwidth available for provisioning. We exploit the additional information of delay and the concept of tree diameter to alleviate the problem. The third problem is the location management problem in Mobile Ad-hoc Networks (MANET). We proposed an integrated location management and location-aided routing system which uses location information as a guidance in QoS routing.
The positive and negative implications of anonymity in Internet social interactions: "On the Internet, Nobody Knows You're a Dog"
Authors: Kimberly M. Christopherson
Venue: Computers in Human Behavior (2007)

The growth of the Internet at a means of communication has sparked the interest of researchers in several fields (e.g. communication, social psychology, industrial-organizational psychology) to investigate the issues surrounding the expression of different social behaviors in this unique social context. Of special interest to researchers is the increased importance that anonymity seems to play in computer-mediated communication (CMC). This paper reviews the literature related to the issues of anonymity within the social context, particularly in CMC, demonstrating the usefulness of established social psychological theory to explain behavior in CMC and discussing the evolution of the current theoretical explanations in explaining the effects of anonymity in social behavior in CMC environments. Several suggestions for future research are proposed in an attempt to provide researchers with new avenues to investigate how anonymity can play both positive and negative roles in CMC.