20191236
Optimal Rebating Strategies in Peer-to-Peer Content Distribution
Developed the algorithms that were the firm's core Intellectual Property (IP) at founding.
14371676
On the Formation of Peer-to-Peer Networks: Self-Organized Sharing and Groups
In this paper, we investigate the formation of peer-to-peer (P2P) networks with rational participating agents (active peers). In the absence of a central planner, peers choose their own utility-maximizing strategies for coalition and peer formation. P2P networks evolve dynamically through the activities of interactions among individual nodes and group units. We propose a framework for multilevel formation dynamics, including an individual level (content sharing decision and group selection) and a group level (membership admission). The respective utilities of the individual node and the collective player are formulated as functions of operational performance metrics such as expected content availability, search delay, transmission delay, and download delay. We study the impacts of various system parameters on the emergence of self-organized P2P network configuration features such as free-riding level and group size. Furthermore, we investigate the stability and efficiency of P2P networks and propose internal transfer mechanisms that force stable networks to become efficient.
10154529
Comparing uniform and flexible policies for software maintenance and replacement
The importance of software maintenance in managing the life-cycle costs of a system cannot be overemphasized. Beyond a point, however, it is better to replace a system rather than maintain it. We derive model and operating policy that reduces the sum of maintenance and replacement costs in the useful life of a software system. The main goal is to compare uniform (occurring at fixed time intervals) versus flexible (occurring at varying, planned time intervals) polices for maintenance and replacement. The model draws from the empirical works of earlier researchers to consider 1) inclusion of user requests for maintenance, 2) scale economies in software maintenance, 3) efficiencies derived from replacing old software technology with new software technology, and 4) the impact of software reuse on replacement and maintenance. Results from our model show that the traditional practice of maintaining or replacing a software system at uniform time intervals may not be optimal. We also find that an increase in software reuse leads to more frequent replacement, but the number of maintenance activities is not significantly impacted.
14496219
Optimal Processing Policies for an e-Commerce Web Server
The explosive growth in online shopping has provided online retailers impressive opportunities to extend revenue and profit. However, retailers may lose considerable online business from slow response times at electronic shopping sites. Although increasing server capacity may improve response time, the resources needed to do so are clearly not free. In this study, we propose a scheme that can improve a server's performance with no more than its current capacity. This scheme is based on priority processing, where the priority assigned to a customer depends on the potential revenue that is likely to be generated from the customer. The results for single-period analysis show that the benefit from priority processing increases as the server becomes more heavily utilized. 
 
We have also modeled a multiperiod version of the problem, where the demand in a period depends on the quality of service (QoS) that buyers receive in the previous period. In the multiperiod problem, both the server capacity and the processing policy in each period are determined optimally. Here, it may be optimal for the retailer to sacrifice profit and increase QoS in initial periods in order to increase demand (and revenue) in later periods. Thus, the processing policy of the server evolves from an emphasis on QoS in initial periods, to one on profit in subsequent periods.
147466
A vision-based approach to early detection of drowning incidents in swimming pools
We present in this paper a vision-based approach to detection of drowning incidents in swimming pools at the earliest possible stage. The proposed approach consists of two main parts: a vision component which can reliably detect and track swimmers in spite of large scene variations of monitored pool areas, and an event-inference module which parses observation sequences of swimmer features for possible drowning behavioral signs. The vision component employs a model-based approach to represent and differentiate the background pool areas and foreground swimmers. The event-inference module is constructed based on a finite state machine, which integrates several reasoning rules formulated from universal motion characteristics of drowning swimmers. Possible drowning incidents are quickly detected using a sequential change detection algorithm. We have applied the proposed approach to a number of video clips of simulated drowning and obtained promising results as reported in this paper.
16126034
Color filter array demosaicking: new method and performance measures
Single-sensor digital cameras capture imagery by covering the sensor surface with a color filter array (CFA) such that each sensor pixel only samples one of three primary color values. To render a full-color image, an interpolation process, commonly referred to as CFA demosaicking, is required to estimate the other two missing color values at each pixel. In this paper, we present two contributions to the CFA demosaicking: a new and improved CFA demosaicking method for producing high quality color images and new image measures for quantifying the performance of demosaicking methods. The proposed demosaicking method consists of two successive steps: an interpolation step that estimates missing color values by exploiting spatial and spectral correlations among neighboring pixels, and a post-processing step that suppresses noticeable demosaicking artifacts by adaptive median filtering. Moreover, in recognition of the limitations of current image measures, we propose two types of image measures to quantify the performance of different demosaicking methods; the first type evaluates the fidelity of demosaicked images by computing the peak signal-to-noise ratio and CIELAB DeltaE(*)(ab) for edge and smooth regions separately, and the second type accounts for one major demosaicking artifact-zipper effect. We gauge the proposed demosaicking method and image measures using several existing methods as benchmarks, and demonstrate their efficacy using a variety of test images.
34798576
Video transcoding for fast forward/reverse video playback
Fast forward and fast reverse playbacks are two common video browsing functions provided in many analog and digital video players. They help users quickly find and access video segments of interest by scanning through the content of a video at a faster than normal playback speed. We propose a video transcoding approach to realizing fast forward and reverse video playbacks by generating a new compressed video from a pre-coded video. To reduce the computational requirements, we design and compare several fast algorithms for estimating the motion vectors required in transcoded video. To accommodate changes due to frame skipping for fast video playback, we also alter the group-of-pictures structure of transcoded video. In addition, subjective tests are conducted to assess the minimum video peak-signal-to-noise-ratio degradation that is perceptible to viewers at different fast playback speeds. To this end, we obtain an adaptive video transcoding method, which combines intra-coding and inter-coding with a fast motion vector reestimation method to strike a good balance between computational complexity and transcoded video quality. Experimental results are reported to show the efficacy of the proposed method.
13163340
Arbitrary downsizing video transcoding using H.26L standard
Downsizing video transcoding is a useful technique for adapting the bit rate or frame size of a precoded video to suit better the constraints of different transmission networks and receiving devices. To avoid frame skipping and maintain good quality at low bit rates, we have proposed H.263-based video transcoding techniques for downszing a precoded video by an arbitrary factor. In this paper, we extend the proposed techniques by using the newly developed H.26L standard in order to fully exploit the advantages of arbitrary downsizing video transcoding. Experimental results show that the proposed method can achieve much better video quality than that using H.263 standard.
27173472
Guest editorial
increasing relevance of security, safety and privacy issues 2 and of d the their perceived or subjective counterpartÈin IT and in particular on the web ; fact that trust is essential for any organization, or any human social d the relation, and thus should be maintained and created in new forms of computer supported collaboration and computer mediated communities ; fact that what is growing on the web is a new market, Electronic d the Commerce (EC), and since a market is mainly based on selÐsh interests, it is open to cheating and to competition between attractive alternatives. Hence, this new virtual market strongly requires trust in the chosen partner, trust in rules and procedures, trust in guaranties and enforcing authorities.