A fundamental problem that confronts peer-to-peer applications is to efficiently locate the node that stores a particular data item. This paper presents Chord, a distributed lookup protocol that addresses this problem. Chord provides support for just one operation: given a key, it maps the key onto a node. Data location can be easily implemented on top of Chord by associating a key with each data item, and storing the key/data item pair at the node to which the key maps. Chord adapts efficiently as nodes join and leave the system, and can answer queries even if the system is continuously changing. Results from theoretical analysis, simulations, and experiments show that Chord is scalable, with communication cost and the state maintained by each node scaling logarithmically with the number of Chord nodes.

Chord: A scalable peer-to-peer lookup service for internet applications

This paper presents the design and evaluation of Pastry, a scalable, distributed object location and routing substrate for wide-area peer-to-peer ap- plications. Pastry performs application-level routing and object location in a po- tentially very large overlay network of nodes connected via the Internet. It can be used to support a variety of peer-to-peer applications, including global data storage, data sharing, group communication and naming. Each node in the Pastry network has a unique identifier (nodeId). When presented with a message and a key, a Pastry node efficiently routes the message to the node with a nodeId that is numerically closest to the key, among all currently live Pastry nodes. Each Pastry node keeps track of its immediate neighbors in the nodeId space, and notifies applications of new node arrivals, node failures and recoveries. Pastry takes into account network locality; it seeks to minimize the distance messages travel, according to a to scalar proximity metric like the number of IP routing hops. Pastry is completely decentralized, scalable, and self-organizing; it automatically adapts to the arrival, departure and failure of nodes. Experimental results obtained with a prototype implementation on an emulated network of up to 100,000 nodes confirm Pastry's scalability and efficiency, its ability to self-organize and adapt to node failures, and its good network locality properties.

/pdf/pastry-scalable-decentralized-object-location-and-routing-1u2equbbbp.pdf

Pastry: Scalable, Decentralized Object Location, and Routing for Large-Scale Peer-to-Peer Systems

Hash tables - which map "keys" onto "values" - are an essential building block in modern software systems. We believe a similar functionality would be equally valuable to large distributed systems. In this paper, we introduce the concept of a Content-Addressable Network (CAN) as a distributed infrastructure that provides hash table-like functionality on Internet-like scales. The CAN is scalable, fault-tolerant and completely self-organizing, and we demonstrate its scalability, robustness and low-latency properties through simulation.

https://www.cs.sjtu.edu.cn/~gchen/course/acn/Reading/CAN.pdf

A scalable content-addressable network

A review of the geologic history of the Himalayan-Tibetan orogen suggests that at least 1400 km of north-south shortening has been absorbed by the orogen since the onset of the Indo-Asian collision at about 70 Ma. Significant crustal shortening, which leads to eventual construction of the Cenozoic Tibetan plateau, began more or less synchronously in the Eocene (50–40 Ma) in the Tethyan Himalaya in the south, and in the Kunlun Shan and the Qilian Shan some 1000–1400 km in the north. The Paleozoic and Mesozoic tectonic histories in the Himalayan-Tibetan orogen exerted a strong control over the Cenozoic strain history and strain distribution. The presence of widespread Triassic flysch complex in the Songpan-Ganzi-Hoh Xil and the Qiangtang terranes can be spatially correlated with Cenozoic volcanism and thrusting in central Tibet. The marked difference in seismic properties of the crust and the upper mantle between southern and central Tibet is a manifestation of both Mesozoic and Cenozoic tectonics. The form...

Geologic Evolution of the Himalayan-Tibetan Orogen

Reliability at massive scale is one of the biggest challenges we face at Amazon.com, one of the largest e-commerce operations in the world; even the slightest outage has significant financial consequences and impacts customer trust. The Amazon.com platform, which provides services for many web sites worldwide, is implemented on top of an infrastructure of tens of thousands of servers and network components located in many datacenters around the world. At this scale, small and large components fail continuously and the way persistent state is managed in the face of these failures drives the reliability and scalability of the software systems.This paper presents the design and implementation of Dynamo, a highly available key-value storage system that some of Amazon's core services use to provide an "always-on" experience. To achieve this level of availability, Dynamo sacrifices consistency under certain failure scenarios. It makes extensive use of object versioning and application-assisted conflict resolution in a manner that provides a novel interface for developers to use.

/pdf/dynamo-amazon-s-highly-available-key-value-store-2ozfk43ou4.pdf

Dynamo: amazon's highly available key-value store

Honeynet-based Botnet Scan Traffic Analysis: Countering the Largest Security Threat

Zanthoxylum armatum DC. extract induces liver injury via autophagy suppression and oxidative damage by activation of mTOR/ULK1 pathway.

In the southern French Massif Central, the Montagne Noire axial zone is a NE-SW elongated granitic-migmatitic dome surrounded by recumbently folded Palaeozoic sedimentary series with a southern vergence. From rim to core, the axial zone consists of micaschist, gneiss, augen orthogneiss, cordierite migmatite, and anatectic granites (Laouzas, Montalet). Syn- to late kinematic granitoids intrude the dome. The relative succession of events in Montagne Noire: 1-recumbent folding, 2-doming and 3-post-migmatitic granitoids intrusion is widely acknowledged. Conversely, the tectonic setting of the doming is disputed. The proposed models do not take into account the granitic and migmatitic structures, geochronology and dome core structure. Therefore, petro-textural and Magnetic Susceptibility Anisotropy studies and new monazite U-Th/Pb datings have been carried out in the Montagne Noire axial zone. The Montalet granite (333±4 Ma) is coeval with migmatization, and the Soulie granite (318±4 Ma) marks dome intrusion. In the dome axial zone rocks, magmatic, late-magmatic, tectonic and metamorphic textures have been recognized. Magnetic mineralogical study indicates that biotite is the main carrier of the magnetic susceptibility in granitic and migmatitic rocks, and that cordierite does not influence vectors directions. The attitude of the magnetic foliation complies with the preferred orientation of biotite, schlierens, enclaves and with migmatitic foliation observed in the field. The AMS fabric confirms the elliptical shape of the axial zone inferred from the migmatitic and gneissic envelope. The southward dipping foliation identified in both flanks is in agreement with an asymmetric dome. Moreover, the magnetic lineations exhibit a contrasting pattern with a dominant NE-SW trend, and a N-S one as well. The AMS features are in agreement with a diapiric component for the migmatite ascent. A model involving diapirism coeval with anticlinal stacking followed by extension discussed.

The emplacement of the Montagne Noire axial zone (French Massif Central): New insights from petro-textural, geochronological and AMS studies

A user-centric no-cell (UCNC) framework has been proposed which enables different level coordination over a large number of TRPs. This paper presents some key technologies in UCNC framework with the focus on PoC of UL grant- free transmissions in UCNC architecture. Massive connectivity support is one of the three important scenarios in 5G networks. The challenges to support massive connectivity lie in the cost of signaling overhead and transmission latency. An uplink grant- free transmission based on SCMA (sparse code multiple access) design is proposed. The proposed scheme can provide different levels of overloading to efficiently meet the massive connectiv- ity requirements. Extensive lab tests have been conducted to verify the performance matrices. Taken LTE as a baseline for comparison purpose, it is shown that the signaling overhead by using uplink grant-free transmission can be reduced by around 80% and the user plane transmission latency in ECO state can be reduced by around 93%. Moreover, massive connectivity is efficiently supported with SCMA scheme that yields around 230% gain over OFDMA in terms of supported active users.

5G PoC of SCMA-Based Uplink Grant-Free Transmission in UCNC Framework

Under the circumstances of global warming and rapid urbanization, damage caused by urban inundation are becoming increasingly severe, attracting the attention of both researchers and governors. The accurate simulation of urban inundation is essential for the prevention of inundation hazards. In this study, a 1D pipe network and a 2D urban inundation coupling model constructed by InfoWorks ICM was used to simulate the inundation conditions in the typical urbanized area in the north of Lin’an. Two historical rainfall events in 2020 were utilized to verify the modeling results. The spatial–temporal variation and the causes of urban inundation under different designed rainfalls were studied. The results were as follows: (1) The constructed model had a good simulation accuracy, the Nash–Sutcliffe efficiency coefficient was higher than 0.82, R2 was higher than 0.87, and the relative error was ±20%. (2) The simulation results of different designed rainfall scenarios indicated that the maximum inundation depth and inundation extent increased with the increase in the return period, rainfall peak position coefficient, and rainfall duration. According to the analysis results, the urban inundation in Lin’an is mainly affected by topography, drainage network (spatial distribution and pipe diameter), and rainfall patterns. The results are supposed to provide technical support and a decision-making reference for the urban management department of Lin’an to design inundation prevention measures.

/pdf/urban-inundation-under-different-rainstorm-scenarios-in-29fjq9rv.pdf

Yan Chen

Papers

Honeynet-based Botnet Scan Traffic Analysis: Countering the Largest Security Threat

Zanthoxylum armatum DC. extract induces liver injury via autophagy suppression and oxidative damage by activation of mTOR/ULK1 pathway.

The emplacement of the Montagne Noire axial zone (French Massif Central): New insights from petro-textural, geochronological and AMS studies

5G PoC of SCMA-Based Uplink Grant-Free Transmission in UCNC Framework

Urban Inundation under Different Rainstorm Scenarios in Lin’an City, China