Knapsack-model-based Schemes and WLB Algorithm for the Capacity and Efficiency Management of Web Cache

Web cache refers to the temporary storage of web files/documents. In reality, a set of caches can be grouped into a cluster to improve the server system's performance. In this paper, to achieve the overall cluster efficiency, we propose a weighted load balancing (WLB) routing algorithm by considering both the cache capability and the content property to determine how to direct an arrival request to the right node. Based on Knapsack models, we characterize three new placement/replacement schemes for Web contents caching and then conduct the comparison based on WLB algorithm. We also compare WLB algorithm with two other widely used algorithms: Pure load balancing (PLB) algorithm and Round-Robin (RR) algorithm. Extensive simulation results show that the WLB algorithm works well under the examined cluster content placement/replacement schemes. It generally results in shorter response time and higher cache hit ratio, especially when the cache cluster capacity is scarce

Potential of Core-Collapse Supernova Neutrino Detection at JUNO

JUNO is an underground neutrino observatory under construction in Jiangmen, China. It uses 20kton liquid scintillator as target, which enables it to detect supernova burst neutrinos of a large statistics for the next galactic core-collapse supernova (CCSN) and also pre-supernova neutrinos from the nearby CCSN progenitors. All flavors of supernova burst neutrinos can be detected by JUNO via several interaction channels, including inverse beta decay, elastic scattering on electron and proton, interactions on C12 nuclei, etc. This retains the possibility for JUNO to reconstruct the energy spectra of supernova burst neutrinos of all flavors. The real time monitoring systems based on FPGA and DAQ are under development in JUNO, which allow prompt alert and trigger-less data acquisition of CCSN events. The alert performances of both monitoring systems have been thoroughly studied using simulations. Moreover, once a CCSN is tagged, the system can give fast characterizations, such as directionality and light curve

Detection of the Diffuse Supernova Neutrino Background with JUNO

As an underground multi-purpose neutrino detector with 20 kton liquid scintillator, Jiangmen Underground Neutrino Observatory (JUNO) is competitive with and complementary to the water-Cherenkov detectors on the search for the diffuse supernova neutrino background (DSNB). Typical supernova models predict 2-4 events per year within the optimal observation window in the JUNO detector. The dominant background is from the neutral-current (NC) interaction of atmospheric neutrinos with 12C nuclei, which surpasses the DSNB by more than one order of magnitude. We evaluated the systematic uncertainty of NC background from the spread of a variety of data-driven models and further developed a method to determine NC background within 15\% with {\it{in}} {\it{situ}} measurements after ten years of running. Besides, the NC-like backgrounds can be effectively suppressed by the intrinsic pulse-shape discrimination (PSD) capabilities of liquid scintillators. In this talk, I will present in detail the improvements on NC background uncertainty evaluation, PSD discriminator development, and finally, the potential of DSNB sensitivity in JUNO

Essays on information service systems

In this thesis, we study information service systems from two perspectives: one is about system and technical problems in Web cache management; another one focuses on business and operation management problems in information system services (ISS). We first discuss efficient placement/replacement schemes for Web content caching based on the Knapsack model. To achieve the overall cluster efficiency, we develop a weighted load balancing (WLB) routing algorithm based on a dynamic programming routing model. The WLB algorithm considers both the cache ca-pability and content property to determine how to direct an arrival request to the right node. Extensive simulation results show that the WLB algorithm works well with the cluster content replacement schemes and together, they lead to shorter response time and higher cache hit ratio. On the other hand, motivated by the new business models operated by many information service companies, we aim at developing insights into the determi-nants of the appropriate supply chain structure of ISS. We integrate the strategy issue and operation issue into the decision making process, to better understand how the service supply chain structure and pricing scheme affect the system per-formance and profit, so that firms may operate with the best design for key service dimensions. We consider the utility-maximization demand model, identify and evaluate methods of coordinating ISS supply chains in which multiple decision makers pursue individual benefits. We formulate the decision problem for each player based on Game Theory, derive the rational behaviors, and characterize the equilibrium results

VPeers: A peer-to-peer service discovery framework for virtual manufacturing organizations

We present VPeers, a peer-to-peer service discovery framework for a Virtual Manufacturing organization (VMO). In our framework, each VPeer (a VMO member) publishes the services that it intends to share and maintains a list of friend VPeers that it has recently interacted with. When a VPeer receives a search query, it will first search its local services. If the search query is not satisfied locally, this VPeer will forward the query to its friend VPeers with an additional time constraint. This process continues recursively until the search query is fully satisfied or the time allowed by the constraint has elapsed. The features of the VPeers framework include: (1) a fully distributed search process; (2) a search query involving both string matches and range predicates; and (3) a ranking scheme that ranks search results by predefined quality measures. Our prototype implementation shows the feasibility of this approach. (c) 2008 Elsevier B.V. All rights reserved