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Real-time online trajectory map-matching has emerged as a critical component in the era of location-based services (LBS) and intelligent transportation systems (ITS). It refers to the process of aligning a user's GPS trajectory data with the corresponding road network in real-time. This technology has significant implications for various industries and applications. As our reliance on LBS and ITS continues to grow, the demand for faster, more accurate, and more reliable trajectory map-matching methods becomes increasingly important. Contemporary online map-matching predominantly employs stream processing techniques. Based on stream processing frameworks, we propose a heterogeneous hybrid architecture for map-matching. The architecture integrates Spark Streaming and graphics processing unit (GPU) heterogeneous computing for the first time. The hidden Markov model is employed as the map-matching algorithm, and Spark Streaming serves as the distributed processing platform. We conduct map-matching experiments using a GPS taxi trajectory dataset in Beijing's Haidian District. The results demonstrate that in comparison to other analogous research, our framework's performance has increased by over ten times, possessing a superior data processing capability and lower latency. This research provides a novel approach of stream-based heterogeneous computation for processing large-scale geographic data. [ABSTRACT FROM AUTHOR]

The emergence of the Digital Twin of Earth (DTE) signifies a pivotal advancement in the field of the Digital Earth, which includes observations, simulations, and predictions regarding the state of the Earth system and its temporal evolution. While the Geospatial Data Cubes (GDCs) hold promise in probing the DTE across time, existing GDC approaches are not well-suited for real-time data ingestion and processing. This paper proposes the design and implementation of a real-time ingestion and processing approach in Geospatial Data Cube (RTGDC), achieved by ingesting real-time observation streams into data cubes. The methodology employs a publish/subscribe model for efficient observation ingestion. To optimize observation processing within the data cube, a distributed streaming computing framework is utilized in the implementation of the RTGDC. This approach significantly enhances the real-time capabilities of GDCs, providing an efficient solution that brings the realization of the DTE concept within closer reach. In RTGDC, two cases involving local and global scales were implemented, and their real-time performance was evaluated based on latency, throughput, and parallel efficiency. [ABSTRACT FROM AUTHOR]

Focused on the problem of unbalanced computing load distribution and low resource utilization in the native scheduling mechanism of big data streaming computing platform, a load balancing strategy based on Tabu search algorithm in heterogeneous environments is proposed and applied to the Apache Flink platform. Firstly, this strategy sets up a job topology model and abstracts the topology of streaming computing jobs as a directed acyclic graph.Therefore, each task slot becomes a node, which lays the foundation for performance evaluation of computing nodes.Secondly, the method imports the performance evaluation model to nodes with performance weights in the directed acyclic graph, and obtains the performance of the nodes through normalization processing; then the evaluation parameters are passed into the Tabu Search for job path optimization, so as to obtain the optimal job path. Finally, by using the CustomizationWrapper interface, this strategy allocates data to the nodes included in the optimal job path and completes the balancing of computational load. The algorithm then passes evaluation parameters into the tabu scheduling algorithm for job path optimization, thereby obtaining the optimal job path. The experimental results show that the load balancing strategy optimized by the Tabu scheduling algorithm reduces the average computing latency by 10-20ms compared to the native Flink platform. The strategy significantly improves resource utilization, and increases average throughput by about 15%. This effectively proves the effectiveness and optimization effect of the load balancing strategy. [ABSTRACT FROM AUTHOR]

Load imbalance severely affects cluster performance, and the polarization of resources due to load skewing leads to further worsening of system throughput and latency problems. The proliferation of tasks to be processed in the big data era leads to more severe load skewing. How to cope with the surge of skewed data stream in the context of big data is a new challenge now. In this paper, we propose a coordinated load balancing strategy on skewed data streams (referred to as St-Stream), which is a two-tier hierarchical system for handling data streams. The proposed strategy is characterized by performing a migration pairing strategy for resources at the task allocation stage by cutting and moving out the tasks of high-load nodes in a hierarchical manner, and the moved-out operators are placed in the routing table, and the routing table operators are moved out to these nodes sequentially according to the tasks required by low-load nodes. We further design a two-tier coordination scheme for the resource allocation problem, which can adjust the skewed load from within the nodes and then dynamically restore the balance between the nodes. We implemented St-Stream on Apache Storm, which achieves a 21% coordination in processing CPU utilization, a 17.6% reduction in latency, and a 0.3 improvement in load balance recovery compared to the baseline design. Our experimental results demonstrate that the proposed load balancing strategy better balances the cluster load and improves the performance of the stream processing system. [ABSTRACT FROM AUTHOR]

Structural health monitoring (SHM) of mega engineering is huge, complex, and time-consuming. To address these challenges, this paper proposes an edge-fog-cloud-based digital twin network and provides its application on a mega dam cluster consisting of three dams along a river. Primary features of the network include an intelligent seismograph signal identification algorithm with Convolutional Neural Network (CNN) in the edge computing layer, a streaming finite element analysis (FEA) method for cumulatively simulating effects of water pressure and continuous seismic ground motion in the fog computing layer, and a real-time 3D virtual model visualization approach on Web driven by FEA response in the cloud computing layer. All processes are automated. Performance analysis indicates that the seismograph signal identification algorithm achieves an impressive accuracy of 95 %, virtual model spatial mapping deviation is only 5 %, and SHM processing speed is 9 times faster than the previous manual work. This digital twin network provides high-efficiency, autonomous and distributed SHM for the mega dam cluster, effectively minimizing labor costs, economic expenses and energy consumption. • Edge-fog-cloud-based distributed network. • Intelligent seismic signal identification algorithm using CNN for system triggering. • Streaming FEA of static water pressure and multiple dynamic seismic ground motion for high-fidelity simulation. • Real-time 3D virtual model visualization algorithm on the Web driven by FEA response. [ABSTRACT FROM AUTHOR]

In a big data stream computing environment, the arrival rate of data streams usually fluctuates over time, posing a great challenge to the elasticity of system. The performance of stream computing system is crucial, especially when dealing with unbounded and fluctuating data streams. Most prior studies have primarily focused on one or two aspects to enable elasticity, often lacking prompt and comprehensive performance optimization. This limitation could lead to a tuning bottleneck, preventing the system's performance from consistently reaching its optimal state. Additionally, many stream computing systems are not intelligently adaptive in real time due to the challenges of manual parameter reconfiguration for fluctuating streams. To better address these issues, we propose a framework named Sgp-Stream, which orchestrates scheduling, grouping and parallelism (Sgp). To enhance the system performance. We conduct the following research: (1) Running experiments to evaluate the impact of different factors such as scheduling, grouping and parallelism on system performance. Results show that factors at a single level usually have an upper limit on tuning system performance, and better overall performance can be achieved by coordinating multi-level factors. (2) Establishing quantitative models for stream application that consider computational cost and communication cost, multi-dimensional featured data stream, data center resources, and latency & throughput performance. (3) Demonstrating the effectiveness of the proposed runtime-aware data stream grouping based on smooth weighted polling, elastic adaptive scheduling based on Linear Deterministic Greedy and elastic scaling strategy based on Gradient Descent in Sgp-Stream, for continuous performance optimization.(4) Evaluating the application latency, throughput and resource utilization objectives using a real-world elastic stream computing system and twitter data set. Experimental results show that, compared to existing state-of-the-art works, the proposed Sgp-Stream outperforms them by reducing latency by 26%–48%, improving throughput by 14%–20%, and increasing resource utilization rate by 15%–21%, especially under increasing data stream input rates. • Experiments show single-level factor are insufficient for optimal system performance. • Establishment the DAG, data stream and resource model from quantitative perspective. • Grouping, scheduling and elastic scaling are coordinated optimization strategies. • Implementation of the prototype Sgp-Stream and its performance evaluation. [ABSTRACT FROM AUTHOR]

Data integrity is a prerequisite for ensuring data availability of IoT data and has received extensive attention in the field of IoT big data security. Stream computing systems are widely used in the field of IoT for real-time data acquisition and computing. However, the real-time, volatility, suddenness, and disorder of stream data make data integrity verification difficult. According to the survey, there is no mature and universal solution. To solve this issue, we constructed a data integrity verification algorithm scheme of the stream computing system (S-DIV) by utilizing homomorphic message authentication code and pseudo-random function security assumption. Furthermore, based on S-DIV, an external data integrity tracking and verification system is constructed to track and analyze the message data stream in real time. By verifying the data integrity of message during the whole life cycle, the problem of data corruption or data loss can be found in time, and error alarm and message recovery can be actively implemented. Then, we conduct the formal security analysis under the standard model and, finally, implement the S-DIV scheme in simulation environment. Experimental results show that the scheme can guarantee data integrity in an acceptable time without affecting the efficiency of the original system. [ABSTRACT FROM AUTHOR]

The physiological signal acquisition and analyzing are important for intelligent health services, human–computer interaction and other applications. Due to the computing power limitation of terminal devices, many analyzing methods of physiological signals are in offline mode. However, in many applications, physiological signal should be analyzed in real time. To overcome this problem, a real-time physiological signal acquisition and analysis method based on fractional calculus and stream computing is proposed. Mobile terminals read the physiological data from sensors and upload them to the stream computing platform. A fractal index is used to estimate the physiological status. Based on the stream computing platform, this index is calculated by distributed parallel computing. The experiment results show this method can distinguish the heart health status and reflect driver mental status to some extent. [ABSTRACT FROM AUTHOR]

As a new platform in big data stream computing, Apache Heron ignores the difference in communication modes between task instances and the unbalance of processing load among nodes, which leads to the decline system performance. To address the problem, this paper designed the model of node resource limitation, the model of communication overhead optimization and the model of data stream relationships among instances, as the foundation to propose the TUR-Heron. The strategy was composed of the node resource limitation algorithm and the instance reallocation algorithm. By judging the criteria for instance reallocation and executing instance reallocation algorithm, this strategy transformed the inter-node data streams into intra-node data streams and minimized the communication overhead of the system. The experimental results show that under the three sets of benchmarks, TUR-Heron reduces the communication overhead between nodes and the response latency of the system compared with the default scheduling strategy, and improves the balance of resource utilization of computing nodes. [ABSTRACT FROM AUTHOR]

In this article, we introduce an automatic stream computing reoptimization flow from ASICs to field-programmable gate arrays (FPGAs). Complex VLSI designs need to be prototyped and/or emulated on FPGAs. The main problem that we address in this article is that configurations optimized when targeting ASICs are often, as we will show in this article, highly un-optimal when remapped onto an FPGA. Thus, this article proposes a method to first generate a variety of dataflow configurations targeting an ASIC given multiple behavioral descriptions for high-level synthesis (HLS) and then, based on a compositional predictive model, automatically reoptimize the dataflow when mapped onto an FPGA. The experimental results show that our proposed method works well and that it is very fast. [ABSTRACT FROM AUTHOR]

In the last years, pattern-based programming has been recognized as a good practice for efficiently exploiting parallel hardware resources. Following this approach, multiple libraries have been designed for providing such high-level abstractions to ease the parallel programming. However, those libraries do not share a common interface. To pave the way, GrPPI has been designed for providing an intermediate abstraction layer between application developers and existing parallel programming frameworks like OpenMP, Intel TBB or ISO C++ threads. On the other hand, FastFlow has been adopted as an efficient object-based programming framework that may benefit from being supported as an additional GrPPI backend. However, the object-based approach presents some major challenges to be incorporated under the GrPPI type safe functional programming style. In this paper, we present the integration of FastFlow as a new GrPPI backend to demonstrate that structured parallel programming frameworks perfectly fit the GrPPI design. Additionally, we also demonstrate that GrPPI does not incur in additional overheads for providing its abstraction layer, and we study the programmability in terms of lines of code and cyclomatic complexity. In general, the presented work acts as reciprocal validation of both FastFlow (as an efficient, native structured parallel programming framework) and GrPPI (as an efficient abstraction layer on top of existing parallel programming frameworks). [ABSTRACT FROM AUTHOR]

Traditional environmental model simulations often use archived data as inputs. Recent advancement of Sensor Web technologies in Spatial Data Infrastructures (SDIs) allows real-time observations to be fed into models to generate "live" models. A key challenge is how to efficiently process observation streams in models, which is particularly important in time-critical cases like disaster management. This paper presents an observation stream computing model for live modelling, which couples Sensor Web and models in stream computing environment to provide timely decision-support information. Observation Streams are proposed as information models to deal with observation stream processing. The approach shows how MapReduce and Apache Spark stream processing can be leveraged to support coupling of observation streams and models. The approach is applied in a disaster management case, where in-situ observation streams are processed to compute the waterlogging information in near real time. The results illustrate applicability and effectiveness of the approach. • A framework for coupling Sensor Web and models in a stream computing environment. • O-Stream information model facilitates the observation stream processing in SPARK. • Case study of the live waterlogging model to support the model cloud. [ABSTRACT FROM AUTHOR]

Reducing power consumption for GPU cluster in large-scale stream computing process can bring various benefits such as reducing operating costs and environmental effect. We formulate the problem of power consumption as a constrained optimization problem, minimizing power state of cluster nodes to reduce power consumption while guaranteeing system performance and reliability. The proposed control model based on Model Prediction Control is designed to make a comprehensive metric of GPU cluster achieve expected performance, energy efficiency and reliability. It is different from the previous models, which just consider power consumption as the sole control objective. The event-triggering mechanism is introduced to reduce control overhead. It successfully separates sampling cluster status signals from control model. So the controller needs not to periodically interrupt computing process to solve optimal solutions. Finally, we evaluate and compare this control model with the previous control model by using artificial and real-world workloads. The experimental results show that our proposed control model is able to outperform existing techniques. [ABSTRACT FROM AUTHOR]

Public opinion monitoring, also known as first story detection, is defined within the topic detection and tracking on a particular Internet news event. Generally, it is used to find news propagation. Traditional method adopts text matching to address opinion monitoring. But it has some limitations such as hidden and latent topic discovery and incorrect relevance ranking of matching results on large-scale data. In this paper, we propose three solutions to live public opinion monitoring: simple keyword computing and matching, simple probabilistic topic computing and matching, and stream-based live probabilistic topic computing and matching. We point out the disadvantages of the first two solutions such as semantic matching and low efficiency on timely big data. Stream-based real-time topic computing and topic matching with query-time document and field boosting are proposed to make substantial improvements. Finally, our topic computing and matching experiments with crawled historical Netease news records show that our approaches are effective and efficient. [ABSTRACT FROM AUTHOR]

Public opinion monitoring, also known as first story detection, is defined within the topic detection and tracking on a particular Internet news event. Generally, it is used to find news propagation. Traditional method adopts text matching to address opinion monitoring. But it has some limitations such as hidden and latent topic discovery and incorrect relevance ranking of matching results on large-scale data. In this paper, we propose three solutions to live public opinion monitoring: simple keyword computing and matching, simple probabilistic topic computing and matching, and stream-based live probabilistic topic computing and matching. We point out the disadvantages of the first two solutions such as semantic matching and low efficiency on timely big data. Stream-based real-time topic computing and topic matching with query-time document and field boosting are proposed to make substantial improvements. Finally, our topic computing and matching experiments with crawled historical Netease news records show that our approaches are effective and efficient. [ABSTRACT FROM AUTHOR]

This article presents an optimization method of the parallelism extraction algorithm using spanning tree that automatically exploits the parallelism and determines an execution order of multiple kernel programs in a distributed environment. In stream‐based computing, efficient parallel execution requires careful scheduling of the invocation of the kernel programs. By mapping a kernel to a node and an I/O stream to an edge, the entire stream process can be treated as a spanning tree. The spanning tree, which allows feedback and feedforward edges, is effective for expressing dependencies that exist among kernels. In spanning tree, the nodes at the same depth do not have edges between them, and thus can be executed in parallel in the case parent nodes have been already executed. The series of the nodes can be executed in a pipelined manner. Thus, the proposed algorithm can extract both spatial and temporal parallelism. However, if the algorithm is applied for feedbacks as it is, because of waiting for the completion of the loop among the nodes, it causes the waste of time. To solve this problem, the parallel pattern can be optimized in the step of generating the communication pattern to increase the degree of parallelism. In addition, because of the difference in execution time among kernels, the load balancing can be considered for an optimization for the algorithm. To evaluate the effectiveness of the optimized algorithm, a k‐means application was developed and parallelized especially for the feedback processing. The results show that the parallel execution using two nodes of a graphics processing unit (GPU) cluster obtained 1.5 times speedup. With load balancing, the parallel execution using four nodes of the cluster obtained up to 3.5 times speedup in 2D‐FFT and 3.0 times speedup in LU decomposition, compared to the execution on a single GPU. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

We discuss the extended parallel pattern set identified within the EU-funded project RePhrase as a candidate pattern set to support data intensive applications targeting heterogeneous architectures. The set has been designed to include three classes of pattern, namely (1) core patterns, modelling common, not necessarily data intensive parallelism exploitation patterns, usually to be used in composition; (2) high level patterns, modelling common, complex and complete parallelism exploitation patterns; and (3) building block patterns, modelling the single components of data intensive applications, suitable for use—in composition—to implement patterns not covered by the core and high level patterns. We discuss the expressive power of the RePhrase extended pattern set and results illustrating the performances that may be achieved with the FastFlow implementation of the high level patterns. [ABSTRACT FROM AUTHOR]

Big data stream computing systems should work continuously to process streams of on-line data. Therefore, fault tolerance is one of the key metrics of quality of service in big data stream computing. In this paper, we propose a fault tolerant framework with deadline guarantee for stream computing called FTDG. First, FTDG identifies the critical path of a data stream graph at a given data stream throughput, and quantifies the system reliability of a data stream graph. Second, FTDG allocates tasks by the fault tolerance aware heuristic and critical path scheduling mechanism. Third, FTDG online optimizes the task scheduling by reallocating the critical vertices on the critical path of the data stream graph to lower the response time and reduce system fluctuations. Theoretical as well as experimental results demonstrate that the FTDG makes a desirable trade-off between high fault tolerance and low response time objectives in big data stream computing environments. [ABSTRACT FROM AUTHOR]

High-performance and low-power computation is required for large-scale fluid dynamics simulation. Due to the inefficient architecture and structure of CPUs and GPUs, they now have a difficulty in improving power efficiency for the target application. Although FPGAs become promising alternatives for power-efficient and high-performance computation due to their new architecture having floating-point (FP) DSP blocks, their relatively narrow memory bandwidth requires an appropriate way to fully exploit the advantage. This paper presents an architecture and design for scalable fluid simulation based on data-flow computing with a state-of-the-art FPGA. To exploit available hardware resources including FP DSPs, we introduce spatial and temporal parallelism to further scale the performance by adding more stream processing elements (SPEs) in an array. Performance modeling and prototype implementation allow us to explore the design space for both the existing Altera Arria10 and the upcoming Intel Stratix10 FPGAs. We demonstrate that Arria10 10AX115 FPGA achieves 519 GFlops at 9.67 GFlops/W only with a stream bandwidth of 9.0 GB/s, which is 97.9 percent of the peak performance of 18 implemented SPEs. We also estimate that Stratix10 FPGA can scale up to 6844 GFlops by combining spatial and temporal parallelism adequately. [ABSTRACT FROM PUBLISHER]

MOST (Method Of Splitting Tsunami) is widely used to solve shallow water equations (SWEs) for simulation of tsunami. This paper presents high-performance and power-efficient computation of MOST for practical tsunami simulation with FPGA. The custom hardware for simulation is based on a stream computing architecture for deeply pipelining to increase performance with a limited bandwidth. We design a stream processing element (SPE) of computing kernels combined with stencil buffers. We also introduce an SPE array architecture with spatial and temporal parallelism to further exploit available hardware resources by implementing multiple SPEs with parallel internal pipelines. Our prototype implementation with Arria 10 FPGA demonstrates that the FPGA-based design performs numerically stable tsunami simulation with real ocean-depth data in single precision by introducing non-dimensionalization. We explore the design space of SPE arrays, and find that the design of six cascaded SPEs with a single pipeline achieves the sustained performance of 383 GFlops and the performance per power of 8.41 GFlops/W with a stream bandwidth of only 7.2 GB/s. These numbers are 8.6 and 17.2 times higher than those of NVidia Tesla K20c GPU, and 1.7 and 7.1 times higher than those of AMD Radeon R9 280X GPU, respectively, for the same tsunami simulation in single precision. Moreover, we proposed a roofline model for stream computing with the SPE array in order to investigate factors of performance degradation and possible performance improvement for given FPGAs. With the model, we estimate that an upcoming Stratix 10 GX2800 FPGA can achieve the sustained performance of 8.7 TFlops at most with our SPE array architecture for tsunami simulation. [ABSTRACT FROM AUTHOR]

Connected vehicles are capable of collecting, through their embedded sensors, and transmitting huge amounts of data at very high frequencies. Leveraging this data can be valuable for many entities: automobile manufacturer, vehicles owners, third parties, etc. Indeed, this 'big data' can be used in a large broad of services ranging from road safety services to aftermarket services (e.g., predictive and preventive maintenance). Nevertheless, processing and storing big data raised new scientific and technological challenges that traditional approaches cannot handle efficiently. In this paper, we address the issue of online (i.e., near real-time) data processing of automotive information. More precisely, we focus on the performance of data fusion to support several millions of connected vehicles. In order to face this performance challenge, we propose novel approaches, based on spatial indexation, to speed up our automotive application. To validate the effectiveness of our proposal, we have implemented and conducted real experiments on PSA Group (PSA Group is the second-largest automobile manufacturer in Europe with about 3 million sold vehicles in 2015) big data streaming platform. The experimental results have demonstrated the efficiency of our spatial indexing and querying techniques. [ABSTRACT FROM AUTHOR]

Earthquake intensity is one of the key components of the decision-making process for disaster response and emergency services. Accurate and rapid intensity calculations can help to reduce total loss and the number of casualties after an earthquake. Modern intensity assessment procedures handle a variety of information sources, which can be divided into two main categories. The first type of data is that derived from physical sensors, such as seismographs and accelerometers, while the second type consists of data obtained from social sensors, such as witness observations of the consequences of the earthquake itself. Estimation approaches using additional data sources or that combine sources from both data types tend to increase intensity uncertainty due to human factors and inadequate procedures for temporal and spatial estimation, resulting in precision errors in both time and space. Here we present a processing approach for the real-time analysis of streams of data from both source types. The physical sensor data is acquired from the U.S. Geological Survey (USGS) seismic network in California and the social sensor data is based on Twitter user observations. First, empirical relationships between tweet rate and observed Modified Mercalli Intensity (MMI) are developed using data from the M6.0 South Napa, CAF earthquake that occurred on August 24, 2014. Second, the streams of both data types are analyzed together in simulated real-time to produce one intensity map. The second implementation is based on IBM InfoSphere Streams, a cloud platform for real-time analytics of big data. To handle large processing workloads for data from various sources, it is deployed and run on a cloud-based cluster of virtual machines. We compare the quality and evolution of intensity maps from different data sources over 10-min time intervals immediately following the earthquake. Results from the joint analysis shows that it provides more complete coverage, with better accuracy and higher resolution over a larger area than either data source alone. [ABSTRACT FROM AUTHOR]

As the huge number of mobile devices (e.g., smart phones, tablets and netbooks) increases, more and more people choose to use the Internet services financed by mobile Internet service providers (MISPs). To provide better services, it is quite necessary for MISPs to analyze the information hidden in the big data stream generated by users. Therefore, processing the real-time big data stream efficiently has become increasingly important. However, traditional static data storage technology fails to meet the demands of real-time data processing. To improve processing capacity, many parallel processing structures are proposed, which brings up the problem about how the parallel devices can be scheduled to maximize their efficiency. Accordingly, a dynamic assignment scheduling algorithm for big data stream processing in mobile Internet services is proposed, and a stream query graph is built to calculate the weight of every edge. The edge with the minimum weight is selected to send tuples. Simulation results show that the proper number of the logic devices can dramatically reduce system response time. Furthermore, system context switching is reduced by increasing the number of tuples sent each time. [ABSTRACT FROM AUTHOR]

Stream computing paradigm focuses on efficiently knowledge updating when immigration and emigration occur simultaneously. Existing stream computing for reasoning with three-way decisions aims at symbolic and complete data. In contrast, the studies on more realistic cases of numerical and symbolic types with potentially incomplete data are preliminary. To efficiently cope with the concept uncertainty, a dynamic neighborhood stream three-way decisions algorithm for incomplete hybrid information systems (DNS3WD) is proposed. Following the setting of flowing into one object and flowing out of another, we dynamically generate all neighborhood classes and decision equivalence classes in the data streaming window. Finally, we deduce the principles of variations of conditional probabilities and update three-way regions accordingly. Theoretically, the time complexity of the non-incremental three-way decisions algorithm (NIH3WD) is about N times that of DNS3WD, where N is the size of the data streaming window. In addition, extensive comparisons against NIH3WD demonstrate that DNS3WD can efficiently leverage the previously acquired knowledge. [ABSTRACT FROM AUTHOR]

As one of the key steps in the processing of airborne light detection and ranging (LiDAR) data, filtering often consumes a huge amount of time and physical memory. Conventional sequential algorithms are often inefficient in filtering massive point clouds, due to their huge computational cost and Input/Output (I/O) bottlenecks. The progressive TIN (Triangulated Irregular Network) densification (PTD) filter is a commonly employed iterative method that mainly consists of the TIN generation and the judging functions. However, better quality from the progressive process comes at the cost of increasing computing time. Fortunately, it is possible to take advantage of state-of-the-art multi-core computing facilities to speed up this computationally intensive task. A streaming framework for filtering point clouds by encapsulating the PTD filter into independent computing units is proposed in this paper. Through overlapping multiple computing units and the I/O events, the efficiency of the proposed method is improved greatly. More importantly, this framework is adaptive to many filters. Experiments suggest that the proposed streaming PTD (SPTD) is able to improve the performance of massive point clouds processing and alleviate the I/O bottlenecks. The experiments also demonstrate that this SPTD allows the quick processing of massive point clouds with better adaptability. In a 12-core environment, the SPTD gains a speedup of 7.0 for filtering 249 million points. [ABSTRACT FROM AUTHOR]

Stream processing is an important emerging computational model for performing complex operations on and across multi-source, high-volume, unpredictable dataflows. We present Flow, a platform for parallel and distributed stream processing system simulation that provides a flexible modeling environment for analyzing stream processing applications. The Flow stream processing system simulator is a high-performance, scalable simulator that automatically parallelizes chunks of the model space and incurs near-zero synchronization overhead for acyclic stream application graphs. We show promising parallel and distributed event rates exceeding 149 million events per second on a cluster with 512 processor cores. [ABSTRACT FROM AUTHOR]

Abstract: Power efficiency investigation has been required in each level of a High Performance Computing (HPC) system because of the increasing computation demands of scientific and engineering applications. Focusing on handling the critical design constraints in the software level that run beyond a parallel system composed of huge numbers of power-hungry components, we optimize HPC program design in order to achieve the best possible power performance on the target hardware platform. The power performance of a CUDA Processing Element (PE) is determined by both hardware factors including power features of each component including with CPU, GPU, main memory and PCI buses, and their interconnection architecture; and software factors including algorithm design and the character of executable instructions performed on it. In this paper, approaches to model and evaluate the power consumption of large scale SIMD computation by CUDA PEs on multi-core and GPU platforms are introduced. The model allows obtaining design characteristic values at the early programming stage, thus benefitting programmers by providing the necessary environment information for choosing the best power-efficient alternative. Based on the model, CPU Dynamic frequency scaling (DFS) can be applied on CUDA PE architecture that adjusts CPU frequency to enhance power efficiency of the entire PE without compromising its computing performance. The power model and power efficiency improvements of the new designs have been validated by measuring the new programs on the real GPU multiprocessing system. [Copyright &y& Elsevier]

Abstract: Designing and constructing of road embankments, deep excavations, landslide and snow avalanche predictions or profiling construction sites in slanting terrain need slope stability evaluations. Determination of a safety factor and the position of a potentially critical slip surface is one of the essential issues in classical and modern soil mechanics, which still remains a very important problem in engineering practice. Most of the stability evaluation methods, i.e. based on limit equilibrium assumptions, need optimization, which can be successfully realized with the assistance of a genetic algorithm. The authors propose a variational approach with a four-step technique to determination of the critical height of a slope, which can be treated as an alternative and variant method to the generally applied limit equilibrium and/or finite element methods. Some common obstacles encountered while adapting classical optimization procedures have been solved by application of a parallel genetic algorithm. Substantial acceleration of computations has been achieved by introducing SIMD stream technology, which generally relies on modern graphics processing units. Examples of the results of a slope stability analysis performed using the fast parallel computation technique are also presented. [Copyright &y& Elsevier]

Die-temperature control to avoid hotspots is increasingly critical in multiprocessor systems-on-chip (MPSoCs) for stream computing. In this context, thermal balancing policies based on task migration are a promising approach to redistribute power dissipation and even out temperature gradients. Since stream computing applications require strict quality of service and timing constraints, the real-time performance impact of thermal balancing policies must be carefully evaluated. In this paper, we present the design of a lightweight thermal balancing policy MiGra, which bounds on-chip temperature gradients via task migration. The proposed policy exploits run-time temperature as well as workload information of streaming applications to define suitable run-time thermal migration patterns, which minimize the number of deadline misses. Furthermore, we have experimentally assessed the effectiveness of our thermal balancing policy using a complete field-programmable-gate-array-based emulation of an actual three-core MPSoC streaming platform coupled with a thermal simulator. Our results indicate that MiGra achieves significantly better thermal balancing than state-of-the-art thermal management solutions while keeping the number of migrations bounded. [ABSTRACT FROM AUTHOR]

The rapid increase in the performance of graphics hardware, coupled with recent improvements in its programmability, have made graphics hardware a compelling platform for computationally demanding tasks in a wide variety of application domains. In this report, we describe, summarize, and analyze the latest research in mapping general-purpose computation to graphics hardware. We begin with the technical motivations that underlie general-purpose computation on graphics processors (GPGPU) and describe the hardware and software developments that have led to the recent interest in this field. We then aim the main body of this report at two separate audiences. First, we describe the techniques used in mapping general-purpose computation to graphics hardware. We believe these techniques will be generally useful for researchers who plan to develop the next generation of GPGPU algorithms and techniques. Second, we survey and categorize the latest developments in general-purpose application development on graphics hardware. [ABSTRACT FROM AUTHOR]

High-performance streaming applications are a new and distinct domain of programs that is increasingly important. The StreamIt language provides novel high-level representations to improve programmer productivity and program robustness within the streaming domain. At the same time, the StreamIt compiler aims to improve the performance of streaming applications via stream-specific analysis and optimizations. In this paper, we motivate, describes and justify the StreamIt language which include a structured model of streams, a messaging system for control, and a natural textual syntax. [ABSTRACT FROM AUTHOR]