| 209431. |
- Uddin, Misbah, et al.
(författare)
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A Bottom-Up Design for Spatial Search in Large Networks and Clouds
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Information in networked systems often has spatial semantics: routers, sensors, or virtual machines have coordinates in a geographical or virtual space, for instance. In this paper, we propose a design for a spatial search system that processes queries against spatial information which is maintained in local databases inside a large networked system. In contrast to previous works in spatial databases and peer-to-peer designs, our design is bottom-up, which makes query routing network-aware and thus efficient, and which facilitates system bootstrapping and adaptation. Key to our design is a protocol that creates and maintains a distributed index of object locations based on information from local databases and the underlying network topology. The index builds upon minimum bounding rectangles (MBRs) to efficiently encode locations. We present a generic search protocol which is based on an echo protocol and uses the index to prune the search space and perform query routing. The response times of search queries increase with the diameter of the network, which is asymptotically optimal. We study the performance of the protocol through simulation in static and dynamic network environments, for different network topologies, and for network sizes upto 100'000 nodes. In all experiments, the overhead incurred by our protocol lies within thirty percent of a hypothetical optimal protocol. In addition, the protocol provides high accuracy under significant churn.
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| 209432. |
- Uddin, Misbah, et al.
(författare)
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A bottom-up design for spatial search in large networks and clouds
- 2018
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Ingår i: International Journal of Network Management. - : WILEY. - 1055-7148 .- 1099-1190. ; 28:6
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Tidskriftsartikel (refereegranskat)abstract
- APPENDIX Information in networked systems often has spatial semantics: routers, sensors, or virtual machines have coordinates in a geographical or virtual space, for instance. In this paper, we propose a design for a spatial search system that processes queries against spatial information that is maintained in local databases inside a large networked system. In contrast to previous works in spatial databases and peer-to-peer designs, our design is bottom-up, which makes query routing network aware and thus efficient, and which facilitates system bootstrapping and adaptation. Key to our design is a protocol that creates and maintains a distributed index of object locations based on information from local databases and the underlying network topology. The index builds upon minimum bounding rectangles to efficiently encode locations. We present a generic search protocol that is based on an echo protocol and uses the index to prune the search space and perform query routing. The response times of search queries increase with the diameter of the network, which is asymptotically optimal. We study the performance of the protocol through simulation in static and dynamic network environments, for different network topologies, and for network sizes up to 100 000 nodes. In most experiments, the overhead incurred by our protocol lies well below 30% of a hypothetical optimal protocol. In addition, the protocol provides high accuracy under significant churn.
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| 209433. |
- Uddin, Mohammed Ayaz, et al.
(författare)
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Enhancing compressive performance in 3D printed pyramidal lattice structures with geometrically tailored I-shaped struts
- 2024
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Ingår i: Materials & design. - : Elsevier BV. - 0264-1275 .- 1873-4197. ; 237
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Tidskriftsartikel (refereegranskat)abstract
- This study examines the compressive response of geometrically tailored pyramidal lattice structures composed of struts with I-shaped cross-sections. Geometrically tailored pyramidal lattices with micro-scale features are 3D printed using the Digital Light Processing (DLP) technique, and their effective elastic modulus, collapse strength and energy absorption capacity are experimentally evaluated under quasi-static compressive loading. Furthermore, detailed non-linear finite element (FE) calculations are performed to examine underlying collapse mechanisms and explore the vast design space offered by the proposed geometrical tailoring scheme. Both the experimental and numerical results show that the geometrically tailored lattice structures outperform conventional pyramidal lattices of equal weight in terms of elastic modulus (+24 %), collapse strength (+21 %) and energy absorption (+68 %). Notably, these strength improvements are attributed to lateral buckling that prompts the I-shaped struts to bend sideways during collapse. Specific cross-sectional designs demonstrate remarkable enhancements in strength and energy absorption, reaching up to 93 % and 161 %, respectively, differentiating them significantly from conventional designs.
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| 209434. |
- Uddin, Mohammed Ayaz, et al.
(författare)
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Enhancing energy absorption capacity of pyramidal lattice structures via geometrical tailoring and 3D printing
- 2024
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Ingår i: Proceedings of ASME 2024 Aerospace Structures, Structural Dynamics, and Materials Conference, SSDM 2024. - : ASME International.
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Konferensbidrag (refereegranskat)abstract
- Pyramidal lattice structures have frequently been employed as the core material in the design of sandwich panels due to their impressive weight-specific strength. However, the struts in pyramidal lattice structures bend when subjected to axial, shear, or bending loads, leading to non-uniform stress distributions, especially at low relative densities. The current work introduces a geometrical tailoring scheme that provides the designer with additional parameters that can be adjusted to tune the cross-sectional properties of the lattice struts with the goal of obtaining more uniform stress distributions across their thickness. Specifically, the conventional square and circular pyramidal lattice struts are reshaped into I-beam-like cross-sections, forming a tailored pyramidal lattice. These geometrically tailored pyramidal lattices are 3D printed via the Digital Light Processing (DLP) technique. The quasi-static compressive responses of the lattices are experimentally evaluated in terms of elastic modulus, collapse strength, and energy absorption capacity. Additionally, the collapse mechanisms of the geometrically tailored structures were assessed via a non-linear finite element analysis which was validated against the experimental evidence. The results substantiate the validity of the geometrical tailoring strategy as the reported energy absorption capacity of the tailored pyramidal lattice structure exhibits a significant enhancement up to 64% and 15% respectively. The latter enhancements were attributed to the lateral buckling of struts, prompting the tailored struts to bend sideways during the collapse phase.
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| 209435. |
- Uddin, Misbah, et al.
(författare)
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A peer-to-peer design for spatial search system
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Information in networked systems often has spatial semantics: routers, sensors, or virtual machines have coordinates in a geographical or virtual space, for instance. In this paper, we propose a peer-to-peer design for a spatial search system that processes queries, such as range or nearest-neighbor queries, on spatial information cached on nodes inside a networked system. Key to our design is a protocol that creates a distributed index of object locations and adapts it to object and node churn. The index is build around the concept of minimum bounding rectangle to efficiently encode locations. We present a search protocol, which is based on an echo protocol that prunes the search space and performs query routing. Simulations show the efficiency of the protocol in pruning the search space, thereby reducing the protocol overhead. For many queries, the protocol efficiency increases with the network size and approaches that of an optimal protocol for large systems. The protocol overhead depends on the network topology and is lower if neighboring nodes are spatially close. In contrast to recent works in spatial databases, our design is bottom-up, which makes query routing network-aware and thus efficient in networked systems.
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| 209436. |
- Uddin, Misbah, et al.
(författare)
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A Query Language for Network Search
- 2013
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Ingår i: Proceedings of the 2013 IFIP/IEEE International Symposium on Integrated Network Management, IM 2013. - New York : IEEE conference proceedings. - 9781467352291 ; , s. 109-117
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Konferensbidrag (refereegranskat)abstract
- Network search makes operational data available in real-time to management applications. In contrast to traditional monitoring, neither the data location nor the data format needs to be known to the invoking process, which simplifies application development, but requires an efficient search plane inside the managed system. This paper presents a query language for network search and discusses how search queries can be executed in a networked system. The search space consists of named objects that are modeled as sets of attribute-value pairs. The data model is more general than the relational model, and the query language is more expressive than relational calculus. The paper shows that distributed query processing can be performed using an echo algorithm and that name resolution can be embedded in query processing. Finally, two use cases for network search are presented, one in networking and one in cloud computing, the latter backed up by a prototype implementation.
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| 209437. |
- Uddin, Mohammad Jalal, et al.
(författare)
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Loss and Thermal Analysis of a 100 kW Converter Module Mounted on a Cold-Plate for Fast Charging Applications
- 2019
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Ingår i: 2019 21st European Conference on Power Electronics and Applications, EPE 2019 ECCE Europe. ; September 2019
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Konferensbidrag (refereegranskat)abstract
- For a 100 kW power converter module for fast charging application, the loss and thermal analysis are performed where the results are presented in this paper. The two-stage power conversion of the converter has an efficiency value of 95%. A liquid cooling system is designed, and thermal performance analysis is performed. The results show that the junction temperature is maintained below 110°C for 8 liters per minute of liquid flow rate by the cooling system.
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| 209438. |
- Uddin, Mohammad Misbah, et al.
(författare)
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Graph search for cloud network management
- 2014
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Ingår i: IEEE/IFIP NOMS 2014 - IEEE/IFIP Network Operations and Management Symposium. - : IEEE conference proceedings. - 9781479909131
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Konferensbidrag (refereegranskat)abstract
- A large part of operational and configuration information in networks and clouds has graph structure, e.g., virtual network topologies, IP flows, communication links of distributed cloud applications. The final objective of this work is to develop a scalable management system that allows real-time management applications, such as network analytics and anomaly detection applications, to search for graph-structured operational information. The paper contains a step towards this objective. The key challenge is to devise an efficient and scalable search process on data that is volatile and distributed across the network infrastructure. Approaches that are currently pursued for distributed graph databases are not applicable in this context. This paper presents design options and possible solutions for engineering a scalable graph search system that supports management applications. It includes a simple information model based on property graphs and a search query language based on keyword search. The architecture of the system centers around a distributed search plane that performs query processing using a network of search nodes. Finally, the paper outlines the design of a search node, which contains a local database that maintains graph partitions.
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| 209439. |
- Uddin, Misbah, 1983-, et al.
(författare)
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Management by Network Search
- 2012
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Ingår i: Proceedings of the 2012 IEEE Network Operations and Management Symposium, NOMS 2012. - New York : IEEE Communications Society. - 9781467302685 ; , s. 146-154
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Konferensbidrag (refereegranskat)abstract
- While networked systems hold and generate vast amounts of configuration and operational data, this data is not accessible through a simple, uniform mechanism. Rather, it must be gathered using a range of different protocols and interfaces. Our vision is to make all this data available in a simple format through a realtime search process which runs within the network and aggregates the data into a form needed by applications - a concept we call network search. We believe that such an approach, though challenging, is technically feasible and will enable rapid development of new management applications and advanced network functions. This paper motivates and formulates the concept of network search, compares it to related concepts like web search, outlines a search architecture, describes the design space and research challenges, and reports on a testbed implementation with management applications built for exploratory purposes of this new paradigm.
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| 209440. |
- Uddin, Misbah, et al.
(författare)
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Real-Time Search in Clouds
- 2013
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Ingår i: Proceedings of the 2013 IFIP/IEEE International Symposium on Integrated Network Management, IM 2013. - New York : IEEE. - 9781467352291 ; , s. 1070-1071
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Konferensbidrag (refereegranskat)abstract
- We developed a novel approach for management of networks/networked systems based on network search [4]. Network search provides a simple, uniform interface, through which human administrators and management applications can obtain network information, configuration or operational, without knowing its schema and location. We believe that the capability of network search will spur the development of new tools for human administrators and enable the rapid development of new classes of network control functions and applications.
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