In this paper, we propose a void avoidance algorithm for the stateless weight routing (SWR) algorithm which was developed stateless geographical routing protocol for wireless sensor and ad hoc networks. In order to de...
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In this paper, we propose a void avoidance algorithm for the stateless weight routing (SWR) algorithm which was developed stateless geographical routing protocol for wireless sensor and ad hoc networks. In order to demonstrate the efficiency of the method we started with the illustration of transmission coverage of relay nodes during the course of routing in the SWR protocol. The threshold value to retransmit a packet defined in the SWR may be used for several purposes including elimination of the void problem. It can be shown that the threshold value provides a tool to balance the tradeoff between energy consumption and reliability.. A number of scenario has been considered to test the performance of the void avoidance (recovery!) algorithm. The initial simulation results indicates the proposed algorithm works with the SWR and providing it with an additional feature of adaptivity for wireless ad hoc and sensor networks.
Most of architectural synthesis techniques target DSP algorithms onto multiprocessor architectures using basic functional units such as adders or multipliers. In this paper, a scheme for the partitioning of the data f...
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Most of architectural synthesis techniques target DSP algorithms onto multiprocessor architectures using basic functional units such as adders or multipliers. In this paper, a scheme for the partitioning of the dataflow graph of a DSP application for a high-level synthesis aimed at a design using multi-modules is proposed. In the propose scheme, the regularity characteristics of DSP application are exploited. Moreover, in order to reduce the number of distinct modules, the near-isomorphism sub-graphs represents the modules are merged together by multiplexing them in time to produce a single adaptable module. This merging process enables the reuse of the adaptable modules by partially reconfiguring them at run time to realize different modules during the running of the DSP dataflow graph. It is seen that a small overhead in terms of the architecture's controller is needed by the modules in order for them to be adapted to perform different computations (multi-modes).
For the compressor operation, surge is a detrimental phenomenon of large oscillating pressure and flow in air compressors, which occurs usually at too low flow rate for a given discharge pressure. For many industrial ...
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For the compressor operation, surge is a detrimental phenomenon of large oscillating pressure and flow in air compressors, which occurs usually at too low flow rate for a given discharge pressure. For many industrial air compressors, surge map is widely used for surge avoidance control. Field operation of centrifugal air compressors for manufacturing plant has shown that the surge map of a compressor may vary dramatically with ambient and operational conditions. In our previous work, data-driven surge map modeling method has been developed to obtain surge maps under different ambient air conditions, where the asymmetric support vector machines (ASVM) were developed for obtaining the surge map models based on actual surge test data. Support vector machine algorithms are generally computationally intensive, which may increase the complexity and cost of implementation. In this paper, a method of effectively selecting the support vectors is applied to the ASVM based surge map modeling framework. The modeling results correctly predict all gathered surge conditions with much less support vectors and lower orders kernel. About four times reduction of model complexity was resulted.
Packet scheduling is a critical component of router data paths because it allows routers to divide bandwidth intelligently between competing flows. A large number of scheduling algorithms annotate packets with time st...
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Packet scheduling is a critical component of router data paths because it allows routers to divide bandwidth intelligently between competing flows. A large number of scheduling algorithms annotate packets with time stamps and subsequently sort these packets according to their annotated time stamp values. For these algorithms the problems of efficiently tagging and sorting packets are still open to investigation. In this paper we propose a data structure and algorithm that reduces the latency of determining the packet with the smallest time stamp to a single memory access time and a small constant number of computation steps, independent of the number of flows serviced by the scheduler. The complexity of inserting a packet into our sorting data structure is logarithmic as a function of the ratio between the maximum packet size and minimum connection weight. The latency of inserting a packet can be hidden by performing insertions of several packets in parallel. This is the fastest sorting data structure known to us. One of the most efficient alternative implementation techniques proposed by Chao et. al. [20] is associated with logarithmic complexity of the scheduling decision time, as a function of the maximum value of packet time stamps. Our solution applies to many different packet fair queuing algorithms including Weighted Fair Queuing [28], Self-Clocked Fair Queuing (SCFQ) [28] and Start Time Fair Queuing [4].
This research studies the problem of evaluating the effect of deceptive data based on the information flow network and the Web of trust. We present an information dissemination model that illustrates the prerequisite ...
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This research studies the problem of evaluating the effect of deceptive data based on the information flow network and the Web of trust. We present an information dissemination model that illustrates the prerequisite for dissemination of information based on the subject and object trusts. To evaluate the effects of deceptive data accurately, we offer a quantitative model that is utilized to calculate to what extent the subjects in the information flow network are affected. The algorithm for evaluating the spread of deceptive data is provided and the time complexity of the algorithm is also analyzed
Multimodal applications require the acquisition and processing of massive amounts of information from multiple sensors. Because this process is beyond the capabilities of a single machine, we developed a sensor networ...
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Multimodal applications require the acquisition and processing of massive amounts of information from multiple sensors. Because this process is beyond the capabilities of a single machine, we developed a sensor network data transport system that can employ the numerous computing devices required to perform the task. The computational and data acquisition processes are thus allocated to components spread across a network of systems. We present the NIST Smart dataflow System II, which is a middleware layer that represents applications as dataflow graphs, and transports information streams between the different computational components of the application.
Although many approaches to dynamic reconfiguration have been proposed, how the impact of reconfiguration on system QoS can be controlled has not been addressed adequately so far. In this paper, we propose an approach...
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Although many approaches to dynamic reconfiguration have been proposed, how the impact of reconfiguration on system QoS can be controlled has not been addressed adequately so far. In this paper, we propose an approach to dynamic reconfiguration of distributed dataflow systems. It is an improvement of our previous work for dynamic reconfiguration with QoS management into distributed environment. Our approach has three features. First, it uses version control, flow trace, and reconfiguration scheduling to avoid logical and physical impact on system QoS. Second, it plans a reconfiguration in a totally automatic way. Third, it executes a reconfiguration by a decentralized protocol to reduce reconfiguration time in distributed environment. We adopt our approach to the reconfiguration of a real world application, the data encryption and digital signature system. Experimental results show that our approach has significant advantages in impact control comparing with other existing approaches.
In this special issue, we focus on the challenges of managing organizational security, examining some of the nontechnical aspects of security that assure that the technology is chosen, implemented, and used appropriat...
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In this special issue, we focus on the challenges of managing organizational security, examining some of the nontechnical aspects of security that assure that the technology is chosen, implemented, and used appropriately and well.
The LHCb experiment is currently being installed at the Large Hadron Collider at CERN (Geneva, Switzerland). In order to reduce the amount of data storage for offline analysis, a trigger system is required. The Level-...
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The LHCb experiment is currently being installed at the Large Hadron Collider at CERN (Geneva, Switzerland). In order to reduce the amount of data storage for offline analysis, a trigger system is required. The Level-0 Decision Unit (LODU) is the central part of the first trigger level. It is a full custom 16 layers board using advanced FPGAs in BGA package. The L0DU receives information from the Level-0 sub-triggers (432 bits @ 80MHz) which transmit the data via high speed optical links running at 1.6Gb/s. The processing is implemented using a 40MHz synchronous pipelined architecture. It performs a simple physical algorithm to compute at 40MHz the Level-0 trigger decision in order to reduce the dataflow down to 1MHz for the next trigger level. The internal design of the processing FPGA is mainly composed by a Partial data Processing (PDP) and a Trigger Definition Unit (TDU). The aim of the PDP is to adjust the clock phase, perform the time alignment, prepare the data for the TDU and monitor the data processing. The TDU is flexible and allows to fully re-configure all the trigger conditions without any re-programming the FPGAs through the Experiment Control System (ECS).
Congestion caused by a large number of interacting TCP flows at a bottleneck network link is different from that caused by a lesser number of flows sending large amounts of data-the former would require cutting do...
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Congestion caused by a large number of interacting TCP flows at a bottleneck network link is different from that caused by a lesser number of flows sending large amounts of data-the former would require cutting down the number of competing flows, while cutting down the data sending rate is sufficient for the latter. However, since existing congestion control schemes view congestion only from a packet- level perspective, they treat both to be the same, resulting in suboptimal performance. We propose two best effort, search-based, session (or flow) level congestion control strategies for the Internet, to complement existing packet-level congestion control schemes. Our strategies control the number of competing flows to optimize for the flow completion rate and the flow completion time. Furthermore, our session control mechanisms do not require any per-flow state or computation at the routers, make no assumption about input traffic characteristics and requirements, avoid starvation of new flows when existing flows do not leave the system, and do not require any end host TCP modifications. Using evaluations under a wide variety of static and varying traffic load conditions, we demonstrate the significant performance and fairness gains that our session control mechanisms provide.
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