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Optical Packet Switching
[chapter]
2005
Emerging Optical Network Technologies
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In this thesis recent research in the area of optical packet switching is reviewed, the main problems in the area are identified and a possible solution to some of the problems, optical burst switching, is studied in more detail. Optical burst switching and the JET protocol are studied by means of a simulation program specially built for this purpose. Avainsanat: optinen pakettikytkentä, optinen purskekytkentä, JET-protokolla iii Preface This work was written in the Networking Laboratory at the
doi:10.1007/0-387-22584-6_5
fatcat:ylydbeiudvgk3muuanpeyu5lju
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... Helsinki University of Technology as a part of Optical Access Networks (OAN) project.
CUBIC
2008
ACM SIGOPS Operating Systems Review
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Limitations of equation-based congestion control
2005
Computer communication review
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We study limitations of an equation-based congestion control protocol, called TFRC (TCP Friendly Rate Control). It examines how the three main factors that determine TFRC throughput, namely, the TCP friendly equation, loss event rate estimation and delay estimation, can influence the longterm throughput imbalance between TFRC and TCP. Especially, we show that different sending rates of competing flows cause these flows to experience different loss event rates. There are several fundamental
doi:10.1145/1090191.1080099
fatcat:deuzxu6wkbdhhhfihlntfzwzjm
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... ns why TFRC and TCP flows have different average sending rates, from the first place. Earlier work shows that the convexity of the TCP friendly equation used in TFRC causes the sending rate difference. We report two additional reasons in this paper: (1) the convexity of 1/x where x is a loss event period and (2) different RTO (retransmission timeout period) estimations of TCP and TFRC. These factors can be the reasons for TCP and TFRC to experience initially different sending rates. But we find that the loss event rate difference due to the differing sending rates greatly amplifies the initial throughput difference; in some extreme cases, TFRC uses around 20 times more, or sometimes 10 times less, bandwidth than TCP.
Thyroid function abnormalities in COVID-19 patients
[article]
2020
medRxiv
pre-print
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The novel coronavirus COVID-19, has caused a worldwide pandemic, impairing several human organs and systems. Whether COVID-19 affects human thyroid function remains unknown. Methods: 84 hospitalized COVID-19 patients in the First Affiliated Hospital, Zhejiang University School of Medicine (Hangzhou, China) were respectively enrolled in this study. In addition, 73 other patients with pneumonia and 819 healthy subjects were included as controls. Results: We found that the levels of TT3 and TSH
doi:10.1101/2020.06.15.20130807
fatcat:3han3kckrbgrro4uqufqt62ima
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... e lower in COVID-19 patients than control groups (p<0.001). Within the group of COVID-19 patients, 61.9% patients (52/84) presented with thyroid function abnormalities. We found a larger proportion of patients in severe condition exhibited thyroid dysfunction than mild/moderate cases (90.4% vs. 50.0%, p < 0.001). Patients with thyroid dysfunction tended to have increased interval time for negative conversion of viral nucleic acid (14.1 ± 9.4 vs. 10.6 ± 8.3 days, p = 0.088). To note, thyroid dysfunction was also associated with decreased lymphocytes (p < 0.001) and increased CRP (p = 0.002). In 7 patients with dynamic changes of thyroid function, we observed the levels of TT3 and TSH gradually increased and reached normal range without thyroid hormone replacement at Day 30 post-admission. The correlation between TT3 and TSH level seemed to be positive rather than negative in the early stage, and gradually turned to be negatively related over time. Conclusions: Thyroid function abnormalities are common in COVID-19 patients, especially in severe cases. This might be caused by virus attack and damage to the thyroid-pituitary axis. Therefore, more attention should be paid to thyroid function during treatment of COVID-19, and close follow-up is also needed after discharge.
Limitations of Equation-Based Congestion Control
2007
IEEE/ACM Transactions on Networking
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Limitations of Equation-Based Congestion Control Injong Rhee and Lisong Xu Abstract-We study limitations of an equation-based congestion control protocol, called TCP-Friendly Rate Control (TFRC). ...
Xu is with the Department of Computer Science and Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0115 USA (e-mail: xu@cse.unl. ...
doi:10.1109/tnet.2007.893883
fatcat:iomkv3tfgzbbteliq7llinmy3a
Minimizing Resource Blocking Rate in GoOBS
2011
2011 IEEE Global Telecommunications Conference - GLOBECOM 2011
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The state of the resources at a destination in Grid computing over OBS architecture (GoOBS) may change between a task's selection of a destination and its arrival at the destination. These changes in the availability of the resources requested at the destination may lead to blocking of tasks, and thus increase the resource blocking rate. In this paper, we investigate the resource scheduling problem in GoOBS. Our objective is to minimize the resource blocking rate by containing the impact of the
doi:10.1109/glocom.2011.6133621
dblp:conf/globecom/SahaDX11
fatcat:ttimg3bxpba6joiawmadzu2qje
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... changes in the availability of the resources at a destination. We propose a non-selfish destination selection paradigm to minimize the resource blocking rate. The selection of a destination by a request is called non-selfish, if the selected destination has sufficient resources available to simultaneously process one or more additional requests. Extensive simulations were performed to validate the effectiveness of the heuristics based on the non-selfish destination selection paradigm. Among the proposed heuristics, the NFFD heuristic is most effective in minimizing the resource blocking rate. Compared to the best existing approach, the NFFD heuristic reduces the resource blocking rate by 21% to 73% in our experiments. 978-1-4244-9268-8/11/$26.00 ©2011 IEEE This full text paper was peer reviewed at the direction of IEEE Communications Society subject matter experts for publication in the IEEE Globecom 2011 proceedings.
TCP Congestion Avoidance Algorithm Identification
2014
IEEE/ACM Transactions on Networking
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The Internet has recently been evolving from homogeneous congestion control to heterogeneous congestion control. Several years ago, Internet traffic was mainly controlled by the traditional RENO, whereas it is now controlled by multiple different TCP algorithms, such as RENO, CUBIC, and Compound TCP (CTCP). However, there is very little work on the performance and stability study of the Internet with heterogeneous congestion control. One fundamental reason is the lack of the deployment
doi:10.1109/tnet.2013.2278271
fatcat:mos5yb47ozeazdhvqfktp4mcb4
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... on of different TCP algorithms. In this paper, we first propose a tool called TCP Congestion Avoidance Algorithm Identification (CAAI) for actively identifying the TCP algorithm of a remote Web server. CAAI can identify all default TCP algorithms (e.g., RENO, CUBIC, and CTCP) and most non-default TCP algorithms of major operating system families. We then present the CAAI measurement result of about 30 000 Web servers. We found that only of the Web servers still use RENO, 46.92% of the Web servers use BIC or CUBIC, and of the Web servers use CTCP. Our measurement results show a strong sign that the majority of TCP flows are not controlled by RENO anymore, and a strong sign that the Internet congestion control has changed from homogeneous to heterogeneous.
Techniques for optical packet switching and optical burst switching
2001
IEEE Communications Magazine
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Wavelength-division multiplexing appears to be the solution of choice for providing a faster networking infrastructure that can meet the explosive growth of the Internet. Several different technologies have been developed so far for the transfer of data over WDM. In this article we survey two new technologies which are still in the experimental stage -optical packet switching and optical burst switching -and comment on their suitability for transporting IP traffic. PACKET CODING TECHNIQUES
doi:10.1109/35.894388
fatcat:oxwtd2lrg5gezbthtjlsdr4a5e
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... al optical packet coding techniques have been studied. There are three basic categories: bit serial, bit parallel, and out-of-band signaling.
All-Optical Network Coding
2010
Journal of Optical Communications and Networking
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Xu are with the Department of Computer Science and Engineering, University of Nebraska at Lincoln, Lincoln, Nebraska 68588-0115. D. ...
doi:10.1364/jocn.2.000175
fatcat:wszfbnxuqng7xldvmvp24x6lva
Extending equation-based congestion control to high-speed and long-distance networks
2007
Computer Networks
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Xu and Helzer [27] propose an analytical model for TFRC traffic and a queueing model for a TFRC client buffer, in order to study the user-perceived media quality. ...
Rhee and Xu [18] analytically and experimentally identify the reasons why TFRC may not give the same throughput as TCP, by examining how the three main factors that determine TFRC throughput, namely, ...
doi:10.1016/j.comnet.2006.11.001
fatcat:xzvgtey2evfjjipmrl3yze7724
Linear Programming Models For Multi-Channel P2P Streaming Systems
2010
2010 Proceedings IEEE INFOCOM
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Most of the commercial P2P video streaming deployments support hundreds of channels and are referred to as multichannel systems. Measurement studies show that bandwidth resources of different channels are highly unbalanced and thus recent research studies have proposed various protocols to improve the streaming qualities for all channels by enabling cross-channel cooperation among multiple channels. However, there is no general framework for comparing existing and potential designs for
doi:10.1109/infcom.2010.5462230
dblp:conf/infocom/WangXR10
fatcat:2egrvyayejaijcp3kl6lxobuii
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... nnel P2P systems. The goal of this paper is to establish tractable models for answering the fundamental question in multi-channel system designs: Under what circumstances, should a particular design be used to achieve the desired streaming quality with the lowest implementation complexity? To achieve this goal, we first classify existing and potential designs into three categories, namely Naive Bandwidth allocation Approach (NBA), Passive Channel-aware bandwidth allocation Approach (PCA) and Active Channel-aware bandwidth allocation Approach (ACA). Then, we define the bandwidth satisfaction ratio as a performance metric to develop linear programming models for the three designs. The proposed models are independent of implementations and can be efficiently solved due to the linear property, which provides a way of numerically exploring the design space of multi-channel systems and developing closedform solutions for special systems. 2 Subscribing to a channel means that a peer joins the overlay of that channel for data dissemination but may or may not watch that channel.
Thyroid Function Abnormalities in COVID-19 Patients
2021
Frontiers in Endocrinology
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PurposeThe novel coronavirus COVID-19, has caused a worldwide pandemic, impairing several human organs and systems. Whether COVID-19 affects human thyroid function remains unknown.MethodsEighty-four hospitalized COVID-19 patients in the First Affiliated Hospital, Zhejiang University School of Medicine (Hangzhou, China) were retrospectively enrolled in this study, among which 22 cases had complete records of thyroid hormones. In addition, 91 other patients with pneumonia and 807 healthy subjects
doi:10.3389/fendo.2020.623792
pmid:33679608
pmcid:PMC7933556
fatcat:qu2t5hzjkjfnna77xqpqgoeafi
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... were included as controls.ResultsWe found that levels of total triiodothyronine (TT3) and thyroid stimulating hormone (TSH) were lower in COVID-19 patients than healthy group (p < 0.001). Besides, TSH level in COVID-19 patients was obviously lower than non-COVID-19 patients (p < 0.001). Within the group of COVID-19, 61.9% (52/84) patients presented with thyroid function abnormalities and the proportion of thyroid dysfunction was higher in severe cases than mild/moderate cases (74.6 vs. 23.8%, p < 0.001). Patients with thyroid dysfunction tended to have longer viral nucleic acid cleaning time (14.1 ± 9.4 vs. 10.6 ± 8.3 days, p = 0.088). To note, thyroid dysfunction was also associated with decreased lymphocytes (p < 0.001) and increased CRP (p = 0.002). The correlation between TT3 and TSH level seemed to be positive rather than negative in the early stage, and gradually turned to be negatively related over time.ConclusionThyroid function abnormalities are common in COVID-19 patients, especially in severe cases. This might be partially explained by nonthyroidal illness syndrome.
TCP Congestion Avoidance Algorithm Identification
2011
2011 31st International Conference on Distributed Computing Systems
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The Internet has recently been evolving from homogeneous congestion control to heterogeneous congestion control. Several years ago, Internet traffic was mainly controlled by the traditional AIMD algorithm, whereas Internet traffic is now controlled by many different TCP algorithms, such as AIMD, BIC, CUBIC, and CTCP. However, there is very little work on the performance and stability study of the Internet with heterogeneous congestion control. One fundamental reason is the lack of the
doi:10.1109/icdcs.2011.27
dblp:conf/icdcs/YangLXDL11
fatcat:j7hpyzkmbfec5fnvffjuhamqle
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... information of different TCP algorithms. In this paper, we first propose a tool called TCP Congestion Avoidance Algorithm Identification (CAAI) for actively identifying the TCP algorithm of a remote web server. CAAI can identify all default TCP algorithms (i.e., AIMD, BIC, CUBIC, and CTCP) and most non-default TCP algorithms of major operating system families. We then present, for the first time, the CAAI measurement result of the 5000 most popular web servers. Among the web servers with valid traces, we found that only 16.85∼25.58% of web servers still use the traditional AIMD, 44.51% of web servers use BIC or CUBIC, and 10.27∼19% of web servers use CTCP. In addition, we found that, for the first time, some web servers use non-default TCP algorithms, some web servers use some unknown TCP algorithms which are not available in any major operating system family, and some web servers use abnormal slow start algorithms. Our CAAI measurement results show a strong sign that the majority of TCP flows are not controlled by AIMD anymore, and a strong sign that the Internet congestion control has already changed from homogeneous to highly heterogeneous.
Stochastic convex ordering for multiplicative decrease internet congestion control
2009
Computer Networks
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Window growth function for congestion control is a strong determinant of protocol behaviors, especially its second and higher-order behaviors associated with the distribution of transmission rates, its variances, and protocol stability. This paper presents a new stochastic tool, called convex ordering, that provides an ordering of any convex function of transmission rates of two multiplicative-decrease protocols and valuable insights into high order behaviors of protocols. As the ordering
doi:10.1016/j.comnet.2008.10.012
fatcat:mlddsr2vuzcqxhgedp7lbakwsy
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... ined by this tool is consistent with any convex function of rates, it can be applied to any unknown metric for protocol performance that consists of some high-order moments of transmission rates, as well as those already known such as rate variance. Using the tool, it is analyzed that a protocol with a growth function that starts off with a concave function and then switches to a convex function (e.g., an odd order function such as x 3 and x 5 ) around the maximum window size in the previous loss epoch, gives the smallest rate variation under a variety of network conditions. Among existing protocols, BIC and CUBIC have this window growth function. Experimental and simulation results confirm the analytical findings.
Non-critical phase-matching conditions for fourth harmonic generation of DKDP crystal
2012
Optical Materials Express
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The non-critical phase matching (PM) conditions of deuterated dihydrogen phosphate (DKDP) crystal are investigated in this paper for fourth harmonic generation (FHG) of Nd:YAG crystal and Nd:glass lasers, which include exterior angle deviation, deuterium content and PM temperature. DKDP crystals of different deuterium content were grown from aqueous solutions and cut for type-I non-critical phase-matching with the direction at 90° to the crystal Z axis (θ = 90°) and at 45° to the crystal X axis
doi:10.1364/ome.2.000735
fatcat:phfrd6u5avb4ro2d5r2mgs6jcm
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... (Ф = 45°). The samples are measured for FHG at 1064 nm and 1053 nm, respectively. The deuterium content of DKDP crystal that supports noncritical phase-matching for FHG experiments is confirmed by measuring the relationship of deuterium content and phase-matching angle. Additionally, the non-critical phase matching temperature is also examined.
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