Open Access Issue
High-Performance Flow Classification of Big Data Using Hybrid CPU-GPU Clusters of Cloud Environments
Tsinghua Science and Technology 2024, 29 (4): 1118-1137
Published: 09 February 2024
Abstract PDF (3.4 MB) Collect

The network switches in the data plane of Software Defined Networking (SDN) are empowered by an elementary process, in which enormous number of packets which resemble big volumes of data are classified into specific flows by matching them against a set of dynamic rules. This basic process accelerates the processing of data, so that instead of processing singular packets repeatedly, corresponding actions are performed on corresponding flows of packets. In this paper, first, we address limitations on a typical packet classification algorithm like Tuple Space Search (TSS). Then, we present a set of different scenarios to parallelize it on different parallel processing platforms, including Graphics Processing Units (GPUs), clusters of Central Processing Units (CPUs), and hybrid clusters. Experimental results show that the hybrid cluster provides the best platform for parallelizing packet classification algorithms, which promises the average throughput rate of 4.2 Million packets per second (Mpps). That is, the hybrid cluster produced by the integration of Compute Unified Device Architecture (CUDA), Message Passing Interface (MPI), and OpenMP programming model could classify 0.24 million packets per second more than the GPU cluster scheme. Such a packet classifier satisfies the required processing speed in the programmable network systems that would be used to communicate big medical data.

Open Access Issue
An Electrical Impedance Imaging System Towards Edge Intelligence for Non-Destructive Testing of Concrete
Tsinghua Science and Technology 2024, 29 (3): 883-896
Published: 04 December 2023
Abstract PDF (3 MB) Collect

In the construction industry, to prevent accidents, non-destructive tests are necessary and cost-effective. Electrical impedance tomography is a new technology in non-invasive imaging in which the image of the inner part of conductive bodies is reconstructed by the arrays of external electrodes that are connected on the periphery of the object. The equipment is cheap, fast, and edge compatible. In this imaging method, the image of electrical conductivity distribution (or its opposite; electrical impedance) of the internal parts of the target object is reconstructed. The image reconstruction process is performed by injecting a precise electric current to the peripheral boundaries of the object, measuring the peripheral voltages induced from it and processing the collected data. In an electrical impedance tomography system, the voltages measured in the peripheral boundaries have a non-linear equation with the electrical conductivity distribution. This paper presents a cheap Electrical Impedance Tomography (EIT) instrument for detecting impurities in the concrete. A voltage-controlled current source, a micro-controller, a set of multiplexers, a set of electrodes, and a personal computer constitute the structure of the system. The conducted tests on concrete with impurities show that the designed EIT system can reveal impurities with a good accuracy in a reasonable time.

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