Duty cycle

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Architecture of low duty-cycle mechanisms

Architecture of low duty-cycle mechanisms

WSN asynchronous MAC low duty-cycle schemes found in the literature; they are mainly two schemes, the first technique is sender-oriented and the second technique is receiver oriented. We explain how MAC low duty-cycle schemes and routing algorithms can be combined in cross-layer approach. We propose two low duty WSN architectures: one is based on B-MAC (Sender-oriented), the second on RI-MAC (Receiver-oriented). The routing is an opportunistic routing algorithm. We will depict several variants for each cross-layer scheme. Depending on the transmission range, we evaluate the average i) packet de- livery probability, ii) delay at each hop, iii) number of hops to reach the sink and iv) end-to-end delivery delay. We compare the simulation results, for each scheme, with those obtained by a simple analytical model using a Pois- son point process. We study the energy consumed when no event is detected and the additional energy to convey a packet to the sink. We show that the gain in energy obtained with a low duty-cycle is very significant.
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Sustainable Traffic Aware Duty-Cycle Adaptation in Harvested Multi-Hop Wireless Sensor Networks

Sustainable Traffic Aware Duty-Cycle Adaptation in Harvested Multi-Hop Wireless Sensor Networks

Fig. 9: CDF of packet delay for the unpredictable profile. VI. R ELATED WORK A. Duty-cycle protocols for beacon-enabled 802.15.4 Several authors proposed algorithms to adapt the duty-cycle to traffic in 802.15.4 beacon-enabled, battery powered WSN but the most advanced one is DCLA [8]. It is an efficient learning algorithm that jointly changes BO and SO according to an advanced traffic estimation based on the superframe utilization (observed by the coordinator), buffer occupancy, and queuing delays (transmitted to the coordinator by each node). An exhaustive comparison with other solutions is done and DCLA clearly outperforms them under various traffic patterns.
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Circuits and protocols for low duty cycle wireless systems

Circuits and protocols for low duty cycle wireless systems

Ultimately, all the techniques help bring the supply voltage low, enabling power savings through reduced switching power. The lower supply voltage also results in lower leakage power, further aiding low-duty cycle operation. Leakage Reduction for the transmitter has also been achieved through a mix of methods. The PA, being the most power hungry active block, requires the most careful design in order to minimize or avoid any on-performance degrada- tion. Negative voltage biasing of the thin-oxide PA transistor has been identified as the optimal scheme for leakage reduction because of minimal parasitics. Addition- ally, a minimum-leakage bias point has been identified, at approximately −200mV where the tradeoff between decreasing subthreshold current and increasing gate leakage current is optimized. Overall, this scheme can achieve 30× leakage re- duction and also shows superior resilience to process and temperature variations. This is mainly attributed to the tighter control of gate leakage as compared to subthreshold current.
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Efficient flooding-based routing protocol with random wake-up for very low duty-cycle WSNs

Efficient flooding-based routing protocol with random wake-up for very low duty-cycle WSNs

Fig. 12: End-to-end delay of data packets as a function of the duty-cycle for a traffic generation period of 60 s, and for the routing protocols. that are rebroadcasted is small. For the Gradient protocol, the end-to-end delay of data packets decreases rapidly when the duty cycle increases, but is still high (from 371 s to 150 s with a traffic period of 5 s, and from 530 s to 28 s with a traffic period of 60 s). Indeed, as the duty cycle increases, there are more opportunities to meet neighbors. The meetings with neighbors also last longer, which means that more packets are exchanged and the beacon overhead is reduced. For E-ADCR, the end-to-end delay of data packets is low (from 4 s to 5 s with a traffic period of 5 s, and from 11 s to 6 s with a traffic period of 60 s). This shows that sending packets to all possible neighbors allow the E-ADCR protocol to find the quickest route for packets (among many other routes). Remember that the delay is computed based on the received packets only (see Figure 10), and it takes into account the time
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History-based MAC Protocol for Low Duty-Cycle Wireless Sensor Networks: the SLACK-MAC Protocol

History-based MAC Protocol for Low Duty-Cycle Wireless Sensor Networks: the SLACK-MAC Protocol

For ZigBee, the protocol of [ 27 ] and SLACK-MAC, the duty-cycle is set to 1 % and is fixed. For X-MAC, the average duty cycle decreases from 8.15 % to 4.65 %, for RI-MAC from 7.24 % to 3.66 %, and for PW- MAC from 7.52 % to 3.34 % when the traffic generation period increases from 5 seconds to 30 seconds. Indeed, for X-MAC and RI-MAC the duty-cycle of node actually depends on the communication opportunities, as nodes having frames to send remain active until they can send their frames. PW-MAC implements a local synchronization, which causes many collisions when multiple transmitters simultaneously send their frames to the same receiver. So, the nodes can make a good prediction without being able to transmit their data. Thus, X-MAC, RI-MAC and PW-MAC yield larger duty- cycles than the other protocols.
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Control strategy to limit duty cycle impact of earthquakes on the LIGO gravitational-wave detectors

Control strategy to limit duty cycle impact of earthquakes on the LIGO gravitational-wave detectors

LIGO completed its most recent observation run (re- ferred as O1) from September 18, 2015 to January 12, 2016. During this period, the detectors were kept in an operating mode and the commissioning activities reduced to minimum. Keeping the detectors in operating mode is a complex task and large environmental disturbances can disrupt this process. These disturbances reduce the duty cycle and observing time, as summarized in table I. Environmental hazards such as earthquakes were one of the primary sources of disturbance during the first observation run. Earthquakes with a Richter magni- tude above 4.5 generated a non-negligible increase of the ground motion in vertical and horizontal directions, from a few mHz to 100mHz, as illustrated by the seismic vi- bration spectra in figure 1. This increase of the ground motion overwhelmed the LIGO seismic isolation system and prevented the detectors from operating. Once the cavities of the interferometer are out of resonance, it can take many hours to return to normal operation, as demonstrated in figure 10. Overall, H1 experienced
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A New Opportunistic Routing Scheme in Low Duty-Cycle WSNs for Monitoring Infrequent Events

A New Opportunistic Routing Scheme in Low Duty-Cycle WSNs for Monitoring Infrequent Events

‡ LiSSi - University of Paris-Est Cr´eteil (UPEC): 122, rue Paul Armangot, 94400 Vitry Sur Seine, France mohamed.zayani@inria.fr, nadjib.aitsaadi@u-pec.fr, paul.muhlethaler@inria.fr Abstract—In this paper, we address opportunistic routing in low-duty cycle wireless sensor networks. A low duty-cycle consists in alternating active and sleep cycles asynchronously in order to save energy. Such a design must take an opportunistic approach in order to cope with the unpredictable appearance of wireless links. In fact, topology-based routing approaches are ineffective in this context. Our main objective is to maximize the network lifespan while guaranteeing i) the routing of packets to the sink and ii) acceptable end-to-end delays, with respect to the needs of military applications as defined in the GETRF project 1 . We
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Efficient Bluetooth Low Energy Operation for Low Duty Cycle Applications

Efficient Bluetooth Low Energy Operation for Low Duty Cycle Applications

BLE is a de facto standard [1] for low-energy short- range personal communications, and a key radio technology for the IoT [2]. It is one of the most widespread wireless communication technology today. BLE is designed to provide lower energy consumption [3], [4], security, ease of use and to avoid interference with higher power IEEE 802.11 networks. Although it implements a duty cycle, there is a great waste of energy because devices do not exclusively communicate for application data exchange. Devices spend a lot of time waiting for packet arrivals, channel sensing, and receiving/transmitting packets intended for connection maintenance and synchroniza- tion activities.
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SLACK-MAC: Adaptive MAC Protocol for Low Duty-Cycle Wireless Sensor Networks

SLACK-MAC: Adaptive MAC Protocol for Low Duty-Cycle Wireless Sensor Networks

Fig. 6. Duty-cycle (which is an approximation of the consumed energy) as a function of the traffic generation period, for a duty-cycle of 1%, and for several protocols. to determine the next activation times, which results into a self-adaptive behavior. We show that SLACK-MAC reaches a good behavior with a limited history size of only six entries. Only few activity cycles are needed to fill the memory lists. Then, we compare SLACK-MAC with existing protocols in terms of frame loss, end-to-end delay and con- sumed energy. We show that our low-cost protocol is able to significantly improve the performance of existing protocols. As future work, we aim to see if using an history can be applied to other existing probabilistic MAC protocols.
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Unit duty-cycle differential flow modulation GC×GC-MS:  insights on the modulation process

Unit duty-cycle differential flow modulation GC×GC-MS: insights on the modulation process

dimension flow to waste, with an obvious negative impact on sensitivity. The present contribution is focused on the development of unit sampling duty cycle methods using flow- modulated comprehensive two-dimensional gas chromatography in combination with mass spectrometry. Specifically, a FM GC×GC-MS approach was developed in which the flows necessary to efficiently flush the modulator were greatly reduced (<5 mL/min) [2]. The

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Adaptive Path Planning for Steerable Needles Using Duty-Cycling

Adaptive Path Planning for Steerable Needles Using Duty-Cycling

VII. C ONCLUSIONS In this paper we proposed a closed-loop strategy for motion planning of steerable needles using duty-cycling and a new Arc-based RRT planner. The use of the duty-cycle technique instead of the usual stop-and-turn gave the system more trajectory possibilities. This multiplicity of solutions is specially useful for the case of steering around obstacles during insertion procedures restricted to a 2D working space. The Arc-based RRT proved to respect the nonholonomic constraints while being fast enough to be used in an intra- operative system. We think it could be easily adapted to a preoperative planner by adding some new features, such as the calculation of initial orientation and insertion point and the possibility for the surgeon of choosing image regions as passage points for the needle.
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MAC Mechanism for a Scalable Wireless Sensor Networks using Independent Duty Cycles

MAC Mechanism for a Scalable Wireless Sensor Networks using Independent Duty Cycles

III. I MPROVING THE ENERGY EFFICIENCY OF A LOW DUTY CYCLE MAC PROTOCOL We identified two main issues in IEEE 802.15.4. First, when the non beacon-enabled mode is used, several nodes cannot sleep and the energy consumption is high. Second, when the beacon-enabled mode is used, the required synchronization is difficult to achieve for a large number of nodes, and the fact that all nodes share the same activity cycle reduces the performance of the MAC protocol (since they all compete for the medium at the same time).

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Collaborative duty cycling strategies in energy harvesting sensor networks

Collaborative duty cycling strategies in energy harvesting sensor networks

Both Liu, Cao, Tang, & Wen (2016), and Jang et al. (2010), describe battery powered wireless sensor systems, in which battery reserves monotonically decrease over time. Energy harvesting capabilities can be a relatively cost effective addi- tion to sensor nodes, extending node lifetime and achievable duty cycle levels. Many sources of energy, especially solar, exhibit strong temporal variations, which lead to fluctuations in battery levels. This presents unique challenges in planning and scheduling the behaviour of sensor nodes. The increased availability of energy enables battery powered sentry nodes with much higher duty cycles than in non-energy harvest- ing networks. But these sentry nodes deplete energy quickly in periods of low energy availability, while sleeping nodes maintain battery reserves. Rotating the set of active nodes based on available battery reserves is an obvious solution to this problem, but careful planning of the sequence of active nodes is needed to ensure network performance meets service requirements during times of low energy availability.
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'Beauty is your duty'. Féminité, citoyenneté et cosmétiques aux États-Unis, 1937-1946

'Beauty is your duty'. Féminité, citoyenneté et cosmétiques aux États-Unis, 1937-1946

Vogue et LHJ font la promotion d’une beauté féminine synonyme de citoyenneté américaine. « L’acte de beauté » est alors présenté comme une composante essentielle du rôle de[r]

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Tee: Traffic-based Energy Estimators for duty cycled Wireless Sensor Networks

Tee: Traffic-based Energy Estimators for duty cycled Wireless Sensor Networks

We show, through simulations performed with COOJA, that using information already available at the gateway, such as the network topology, improves the performance of traffic-based estimators. However, only looking at the traffic passing through the gateway is not enough to have an accurate estimation. A rescaling mechanism is necessary to account for the effect of duty cycling at the MAC layer, since the sleeping interval introduces a desynchronization between emitters and receivers, which results in multiple transmission attempts for each frame. Even in the case of a constant bit rate traffic, nodes need to send explicit energy reports, that we called recalibrations, to the gateway, at least in the network initialization phase. This is necessary to take into account the routing packets exchanged to build the initial tree. In case of a static network and a regular traffic pattern, such recalibrations rapidly become unnecessary. In presence of nodes mobility, the control traffic due to the reconstruction of the routing tree will most likely make such explicit recalibrations necessary throughout the network life. In presence of an irregular traffic pattern, we believe that the dynamic can be captured by the gateway, as it is generally the source or the destination of traffic.
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Alcohol Fueled Heavy Duty Vehicles Using Clean, High Efficiency Engines

Alcohol Fueled Heavy Duty Vehicles Using Clean, High Efficiency Engines

The investigation by Blumberg showed that a diesel engine and a downsized engine have just about the same efficiencies, throughout the range. There is slightly higher efficiency at high load, slightly lower efficiency at the lower loads, as shown in Figure 6. Two engines have been considered. A conventional heavy duty diesel engine with 11 liter displacement (Volvo engine, MD11). The second engine is a gasoline engine, 7 liter, using the alcohol boosted concept, with a displacement of 7 liter. At the higher torque points, it is required to have most of the fuel directly injected, if the antiknock agent is E85. If, however, hydrous ethanol is used instead, the amount of antiknock agent can be decreased by about a factor of about 2 [Blumberg1].
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The assessment of using SI engines for medium-duty applications

The assessment of using SI engines for medium-duty applications

The results from the engine simulations provide insight into the comparison of the usability and economy of using an SI engine and a diesel engine in medium duty trucks.After a[r]

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Camera-based indirect vision systems for heavy duty vehicles: phase I

Camera-based indirect vision systems for heavy duty vehicles: phase I

The changes in vehicle fuel consumption per year resulting from the power consumption, mass change, and change in vehicle drag coefficients as a result of the use of the prototype camer[r]

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Deterioration of oxide-coated cathodes under low duty-factor operation

Deterioration of oxide-coated cathodes under low duty-factor operation

The results obtained in this work have shown that the anomalous deterioration that occurs in oxide cathodes coated on silicon-bearing nickel cores when they are o[r]

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Pitfalls and Prospects of Sustainability Risk Management under the Modern Investors’ Fiduciary Duty

Pitfalls and Prospects of Sustainability Risk Management under the Modern Investors’ Fiduciary Duty

STRAKODONSKAYA Liudmila| Thèse de doctorat | Octobre 2019 viewed as myopic and pushing corporate managers of companies they invest in to myopic behaviour as well (Stein 1988, 1989). The research by the Bank of England warns about a rising tide of myopia that could potentially present one of the causes of market failure (Haldane & Davies, 2011). On the other hand, other authors find arguments against the popular myth that the short-term profit pressures of large institutional stockholders influence the decisions by a company management (Hansen & Hill 1991). 260 Many scholars today also study the so-called practice of long-term value creation (Alexander, 2017) arguing that investors are aware of the risks related to myopia and thus refocus on a fundamental value of projects and companies they invest in. Generally, several authors defended the financial securities market by stating that capital markets are efficient and, thus, not short-sighted, meaning that they penalise myopic behaviour by companies’ management (Jensen, 1988 and more recently Tong, 2014). Together these research works offer a great overview on the question of market (investors’) time preferences and some of them explain particular types of investors’ behaviour in reality. However, they do not present a direct answer to the question we raise in this research, which is: could an investor under the Fiduciary Duty rule be assigned any restrictions related to her time preferences? Or, otherwise saying, does the compliance with the fiduciary duty standard imply any particular considerations concerning the discount rate as applied by investors?
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