scholarly journals A Workload-Adaptive Streaming Partitioner for Distributed Graph Stores

2021 ◽  
Author(s):  
Ali Davoudian ◽  
Liu Chen ◽  
Hongwei Tu ◽  
Mengchi Liu
Keyword(s):  
Graph Partitioning ◽  
State Of The Art ◽  
Adaptive Streaming ◽  
Large Graphs ◽  
Load Imbalance ◽  
Graph Queries ◽  
The Impact ◽  
Query Patterns ◽  
Dynamic Query

AbstractStreaming graph partitioning methods have recently gained attention due to their ability to scale to very large graphs with limited resources. However, many such methods do not consider workload and graph characteristics. This may degrade the performance of queries by increasing inter-node communication and computational load imbalance. Moreover, existing workload-aware methods cannot consistently provide good performance as they do not consider dynamic workloads that keep emerging in graph applications. We address these issues by proposing a novel workload-adaptive streaming partitioner named WASP, that aims to achieve low-latency and high-throughput online graph queries. As each workload typically contains frequent query patterns, WASP exploits the existing workload to capture active vertices and edges which are frequently visited and traversed, respectively. This information is used to heuristically improve the quality of partitions either by avoiding the concentration of active vertices in a few partitions proportional to their visit frequencies or by reducing the probability of the cut of active edges proportional to their traversal frequencies. In order to assess the impact of WASP on a graph store and to show how easily the approach can be plugged on top of the system, we exploit it in a distributed graph-based RDF store. Our experiments over three synthetic and real-world graph datasets and the corresponding static and dynamic query workloads show that WASP achieves a better query performance against state-of-the-art graph partitioners, especially in dynamic query workloads.

scholarly journals Smoothing additive manufactured parts using ns-pulsed laser radiation

2021 ◽  
Author(s):  
Florian Kuisat ◽  
Fernando Lasagni ◽  
Andrés Fabián Lasagni
Keyword(s):  
Surface Roughness ◽  
Mechanical Performance ◽  
State Of The Art ◽  
Pulsed Laser ◽  
Industrial Applications ◽  
Laser Source ◽  
Pulsed Laser Radiation ◽  
Current State ◽  
The Impact

AbstractIt is well known that the surface topography of a part can affect its mechanical performance, which is typical in additive manufacturing. In this context, we report about the surface modification of additive manufactured components made of Titanium 64 (Ti64) and Scalmalloy®, using a pulsed laser, with the aim of reducing their surface roughness. In our experiments, a nanosecond-pulsed infrared laser source with variable pulse durations between 8 and 200 ns was applied. The impact of varying a large number of parameters on the surface quality of the smoothed areas was investigated. The results demonstrated a reduction of surface roughness Sa by more than 80% for Titanium 64 and by 65% for Scalmalloy® samples. This allows to extend the applicability of additive manufactured components beyond the current state of the art and break new ground for the application in various industrial applications such as in aerospace.

scholarly journals Condensation of refrigerant R407C in multiport minichannel section

2016 ◽  
Vol 37 (4) ◽  
pp. 3-18
Author(s):  
Tadeusz Bohdal ◽  
Henryk Charun ◽  
Małgorzata Sikora
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Flow Resistance ◽  
State Of The Art ◽  
Condensation Process ◽  
Test Results ◽  
Pressure Drops ◽  
The Impact ◽  
Made In

AbstractAnalysis of the state of-the-art in research of refrigerant condensation in miniature heat exchangers, so-called multiports, was made. Results of refrigerant R407C condensation in a mini condenser made in the form of two bundles of tubular minichannels from stainless steel with an inside diameter 0.64 mm and length 100 mm have been presented. Two exchangers consisted of four minichannels and 8 minichannels have been investigated. The values of average heat transfer coefficient and frictional pressure drops throughout the condensation process were designated. The impact of the vapor quality of refrigerant and the mass flux density on the intensity of heat transfer and flow resistance were illustrated. A comparative analysis of test results for various refrigerants in both mini heat exchangers were made.

scholarly journals One-Way Nested Regional Climate Simulations and Domain Size

2005 ◽  
Vol 18 (1) ◽  
pp. 229-233 ◽  
Author(s):  
S. Vannitsem ◽  
F. Chomé
Keyword(s):  
Western Europe ◽  
State Of The Art ◽  
Regional Climate ◽  
Domain Size ◽  
Regional Model ◽  
Dynamical Behaviors ◽  
Climate Simulations ◽  
Intermediate Size ◽  
The Impact

Abstract The impact of domain size on regional climate simulations is explored in the context of a state-of-the-art regional model centered over western Europe. It is found that the quality of the climate simulations is highly dependent on the domain size. Moreover, the choice of an optimal version is more complex than usually thought, the less appropriate domain having an intermediate size (about 3000 km × 3000 km), and the best versions nearly cover a quarter of the Northern Hemisphere. The use of periodically reinitialized trajectories does improve the climate of suboptimal models but leads to unrealistic dynamical behaviors. The implications for regional climate simulations are briefly discussed.

Online Social Exergames for Seniors

2020 ◽  
pp. 1599-1631
Author(s):  
Stathis Th. Konstantinidis ◽  
Ellen Brox ◽  
Per Egil Kummervold ◽  
Josef Hallberg ◽  
Gunn Evertsen ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Physical Activity ◽  
Physical Training ◽  
State Of The Art ◽  
Social Contact ◽  
High Quality ◽  
Current State ◽  
The Future ◽  
The Impact

The population is getting older, and the resources for care will be even more limited in the future than they are now. There is thus an aim for the society that the seniors can manage themselves as long as possible, while at the same time keeping a high quality of life. Physical activity is important to stay fit, and social contact is important for the quality of life. The aim of this chapter is to provide a state-of-the-art of online social exergames for seniors, providing glimpses of senior users' opinions and games limitations. The importance of the motivational techniques is emphasized, as well as the impact that the exergames have to seniors. It contributes to the book objectives focusing on current state and practice in health games for physical training and rehabilitation and the use of gamification, exploring future opportunities and uses of gamification in eHealth and discussing the respective challenges and limitations.

scholarly journals State-of-the-art ultrasonic sensor designed to improve longwall production rates and operation safety

2021 ◽  
pp. 149-160
Keyword(s):  
State Of The Art ◽  
Ultrasonic Transducers ◽  
Structural Elements ◽  
Rock Falls ◽  
Longwall Panel ◽  
The Face ◽  
Path Measurement ◽  
Closed Structure ◽  
The Impact

The article describes issues related to the development of a sensor measuring the distance from the end of the shield support canopy to the face of the longwall panel. The sensor's task is to detect rock falls because in such a case, empty spaces in the coal seam below the roof are generated. The sensor is a part of the system which task is to predict unfavourable behaviour of the longwall roof affecting the continuity of mining. Due to an untypical workplace and difficult conditions prevailing there, it was not possible to use a typical sensor. The ultrasonic technique was used for this purpose. The next research stages related to the development of the sensor were described. Tests of various types of ultrasonic transducers, working at different parameters, were described. Only transducers with a closed structure were considered because they can operate in the presence of high dustiness and humidity. The sensor casing was adapted to a specific type of shield support. The installation location should not be accidental, as an additional hinged shield is mounted at the end of the canopy, which is an obstacle in the measuring track and can even completely cover it, making measurements impossible. The sensor is mounted close to the side edge of the shield support canopy using small free space, enabling a measurement. Structural elements of the canopy are obstacles in the measuring track and are a source of interference of the received signals. The ultrasonic transducers are built-in tubes, which direct the ultrasonic wave and amplify the received signals. The results of laboratory tests of the model of the path measurement sensor are presented. They describe the impact of analysed aspects, i.e. the type of transducers used, the structure of the surface that the wave is reflected from and the mechanical solutions on the quality of received signals. A prototype of a sensor installed on shield support is presented.

scholarly journals Capturing the interplay of dynamics and networks through parameterizations of Laplacian operators

2016 ◽  
Vol 2 ◽  
pp. e57 ◽  
Author(s):  
Xiaoran Yan ◽  
Shang-hua Teng ◽  
Kristina Lerman ◽  
Rumi Ghosh
Keyword(s):  
Network Topology ◽  
Network Structure ◽  
Graph Partitioning ◽  
Laplacian Matrix ◽  
Dynamical Process ◽  
Dynamical Processes ◽  
Quality Function ◽  
The Impact ◽  
Laplacian Operators

We study the interplay between a dynamical process and the structure of the network on which it unfolds using the parameterized Laplacian framework. This framework allows for defining and characterizing an ensemble of dynamical processes on a network beyond what the traditional Laplacian is capable of modeling. This, in turn, allows for studying the impact of the interaction between dynamics and network topology on the quality-measure of network clusters and centrality, in order to effectively identify important vertices and communities in the network. Specifically, for each dynamical process in this framework, we define a centrality measure that captures a vertex’s participation in the dynamical process on a given network and also define a function that measures the quality of every subset of vertices as a potential cluster (or community) with respect to this process. We show that the subset-quality function generalizes the traditional conductance measure for graph partitioning. We partially justify our choice of the quality function by showing that the classic Cheeger’s inequality, which relates the conductance of the best cluster in a network with a spectral quantity of its Laplacian matrix, can be extended to the parameterized Laplacian. The parameterized Laplacian framework brings under the same umbrella a surprising variety of dynamical processes and allows us to systematically compare the different perspectives they create on network structure.

scholarly journals RBSEP: a reassignment and buffer based streaming edge partitioning approach

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Monireh Taimouri ◽  
Hamid Saadatfar
Keyword(s):  
Graph Partitioning ◽  
Input Data ◽  
Large Datasets ◽  
Greedy Heuristics ◽  
The Internet ◽  
Large Graphs ◽  
New Approach ◽  
The Past ◽  
Edge Partitioning

Abstract In recent years, the rapid growth of the Internet has led to creation of massively large graphs. Since databases have become very large nowadays, they cannot be processed by a simple machine at an acceptable time anymore; therefore, traditional graph partitioning methods, which are often based on having a complete image of the entire graph, are not applicable to large datasets. This challenge has led to the appearance of a new approach called streaming graph partitioning. In streaming graph partitioning, a stream of input data is received by a partitioner, and partitioner decides which computational machine the data should be transferred to. Often, streaming partitioner does not have any information about the whole graph, and usually distributes the vertices based on some greedy heuristics which may not be optimal for incoming vertices. Hence, partitioner’s decision can be significantly improved if more information about the graph is utilized. In this paper, we present a new vertex-cut streaming graph partitioning approach. The proposed method uses the idea of postponing the decision for some of the edges (by means of an intelligent buffering) and corrects some of the past decisions to improve the quality of the graph partitioning. The proposed approach is evaluated using from real-world graphs. The experimental results show that the performance of the proposed method is superior in comparison with the previous HDRF method.

Online Social Exergames for Seniors

2016 ◽  
pp. 245-276 ◽  
Author(s):  
Stathis Th. Konstantinidis ◽  
Ellen Brox ◽  
Per Egil Kummervold ◽  
Josef Hallberg ◽  
Gunn Evertsen ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Physical Activity ◽  
Physical Training ◽  
State Of The Art ◽  
Social Contact ◽  
High Quality ◽  
Current State ◽  
The Future ◽  
The Impact

The population is getting older, and the resources for care will be even more limited in the future than they are now. There is thus an aim for the society that the seniors can manage themselves as long as possible, while at the same time keeping a high quality of life. Physical activity is important to stay fit, and social contact is important for the quality of life. The aim of this chapter is to provide a state-of-the-art of online social exergames for seniors, providing glimpses of senior users' opinions and games limitations. The importance of the motivational techniques is emphasized, as well as the impact that the exergames have to seniors. It contributes to the book objectives focusing on current state and practice in health games for physical training and rehabilitation and the use of gamification, exploring future opportunities and uses of gamification in eHealth and discussing the respective challenges and limitations.

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