1,046 research outputs found
An ineqality for L^infty-norm of eigenfunctions of linear second order elliptic operators
No full textDon't kill my ads! balancing privacy in an ad-supported mobile application market
No full textApplication markets have revolutionized the software download model of mobile phones: third-party application developers offer software on the market that users can effortlessly install on their phones. This great step forward, however, also imposes some threats to user privacy: applications often ask for permissions that reveal private information such as the user's location, contacts and messages. While some mechanisms to prevent leaks of user privacy to applications have been proposed by the research community, these solutions fail to consider that application markets are primarily driven by advertisements that rely on accurately profiling the user. In this paper we take into account that there are two parties with conflicting interests: the user, interested in maintaining their privacy and the developer who would like to maximize their advertisement revenue through user profiling. We have conducted an extensive analysis of more than 250,000 applications in the Android market. Our results indicate that the current privacy protection mechanisms are not effective as developers and advert companies are not deterred. Therefore, we designed and implemented a market-aware privacy protection framework that aims to achieve an equilibrium between the developer's revenue and the user's privacy. The proposed framework is based on the establishment of a feedback control loop that adjusts the level of privacy protection on mobile phones, in response to advertisement generated revenue
Additive Increase Early Adaptive Decrease Mechanism for TCP Congestion Control
No full textDue to the fundamental end-to-end design principle, today TCP/IP congestion control algorithm implements an additive increase multiplicative decrease (AIMD) probing algorithm. We propose a new mechanism that we call additive increase early adaptive decrease (AIEAD). The AIEAD algorithm estimates both the available bandwidth and the queue backlog in a end-to-end fashion: the backlog estimate aims at bounding queue lengths, detecting congestion before overflow and discriminating congestion losses from losses that are due to unreliable links; the bandwidth estimate aims at adaptively setting control windows after congestion detection by taking into account the used bandwidth at the time of congestion (early adaptive decrease phase). An implementation of the AIEAD paradigm, which we call New Westwood (NW), is tested and compared with Reno, and Vegas TCP using the ns-2 simulator. Simulations show that NW significantly improves fairness and goodput with respect to both Reno and Vegas, whereas in a last-hop wireless lossy link scenario NW significantly improves the goodpu
Intraprotocol fairness and interprotocol friendliness of TFRC congestion control algorithm
No full textThe TCP-friendly rate control (TFRC) algorithm has been proposed
for supporting applications such as video streaming or telephony over
the Internet, where a relative smooth sending rate is of importance.
The fairness and friendliness of TFRC over scenarios with multiple
congested routers is evaluated. Results obtained using the ns-2
simulator show that while TFRC improves network utilisation with
respect to Reno TCP, it exhibits a significant degree of unfairness and
unfriendliness towards Reno TCP
End-to-end bandwidth estimation algorithms for Westwood TCP congestion control
No full textWestwood TCP improves efficiency of classic TCP congestion control by introducing an innovative end-to-end bandwidth estimation algorithm. It leaves unchanged the probing phase of classic TCP but it substitutes the multiplicative decrease phase with an adaptive decrease phase, which sets the control windows by taking into account the bandwidth estimate. We show that bunched ACKs can heavily affect the bandwidth estimate and therefore it is necessary to implement an antiACK compression algorithm to properly filter out their effects. Moreover, a comparison of time-invariant and time-varying discrete filters to be used after the antiACK compression algorithm is developed
A CONGESTION CONTROL ALGORITHM FOR THE PLANETARY INTERNET
No full textThis paper proposes a new rate based congestion control algorithm that significantly improves the utilization of planetary links with respect to classic TCP congestion control. Ns-2 simulation results have shown that the proposed algorithm provides significant goodput improvements with respect to New Reno, Reno Sack, Reno Fack, Vegas, and Westwood+ TCP in the presence of RTTs larger than 1s and smaller than 2000s and packet loss probability ranging from 0.0001 to 0.01
Performance evaluation and comparison of Westwood+, New Reno, and Vegas TCP congestion control
No full textTCP congestion control has been designed to ensure Internet
stability along with fair and efficient allocation of the network
bandwidth. During the last decade, many congestion control
algorithms have been proposed to improve the classic Tahoe/Reno
TCP congestion control. This paper aims at evaluating and
comparing three control algorithms, which are Westwood+, New
Reno and Vegas TCP, using both Ns-2 simulations and live
Internet measurements. Simulation scenarios are carefully
designed in order to investigate goodput, fairness and friendliness
provided by each of the algorithms. Results show that Westwood+
TCP is friendly towards New Reno TCP and improves fairness in
bandwidth allocation whereas Vegas TCP is fair but it is not able
to grab its bandwidth share when coexisting with Reno or in the
presence of reverse traffic because of its RTT-based congestion
detection mechanism. Finally results show that Westwood+
remarkably improves utilization of wireless links that are affected
by losses not due to congestion
Efficiency, Fairness and Friendliness Evaluation of TFRC and ARC Rate-Based Congestion Control
No full textThis paper has focused on two rate-based congestion control algorithms, namely TCP-friendly rate control (TFRC) and the adaptive rate control (ARC), for streaming flows over the Internet. After a brief description of the two algorithms, computer simulations using ns-2 have been reported to investigate intra-protocol fairness, inter-protocol friendliness and efficiency. The main results are given: (1) ARC is friendly towards Reno TCP whereas TFRC is not; (2) ARC increases fairness; (3) ARC remarkably improves the goodput with respect to TFRC and Reno TCP in the presence of wireless lossy links
Thirty contaminants of emerging concern identified in secondary treated hospital wastewater and their removal by solar Fenton (like) and sulphate radicals-based advanced oxidation processes
No full textThirty contaminants of emerging concern (CECs) were identified and quantified in hospital wastewater (HWW) by LC-MS and their removal by solar photo Fenton (SPF) with ethylenediamine-N,N’-disuccinic acid (EDDS) at spontaneous pH (7.5) was compared to other solar driven advanced oxidation processes (AOPs) (namely, sun-light/persoxydisulphate (SPD) and sunlight/H2O2 (SHP)). Almost all the detected CECs (28) are pharmaceuticals and belong to 13 different classes, with concentrations varied between 0.08 μg/L (psychiatric drug) to 38.92 μg/L (antidiabetic). First, the formation of iron-EDDS complexes was characterized by electrochemical methods to compare Fe2+and Fe3+behavior. The effect on a carbamazepine (CBZ) aqueous solution of solar driven Fe2+/ EDDS and Fe3+/EDDS Fenton processes was comparatively evaluated to select the most effective one for advanced oxidation tests on real HWW and sunlight/Fe2+-EDDS/H2O2 was the most effective one with 48% removal after 12.5 kJ/L-1 (78% total removal, 30% being under dark Fenton condition). SPF process was also more effective than SPD and SHP (60 min sunlight exposure, 5 kJ/L-1). Subsequently, the effect of the solar AOPs (SPF, Fe2+0.1 mM, EDDS 0.2 Mm, H2O2 2.7 Mm; SPD, PD 1.48 mM; SHP, H2O2 2.7 Mm; 60 min sunlight exposure) was investigated in the treatment of the HWW and SPF resulted the most effective one, all CECs being removed from 70% to 100%
- …
