File Name: low duty cycle protocols and wake up concepts ppt to .zip
- Prolonging the Lifetime of Wireless Sensor Networks: A Review of Current Techniques
- Wireless sensor network
- Wireless sensor network
Prolonging the Lifetime of Wireless Sensor Networks: A Review of Current Techniques
Show all documents In this MPTC, active vector duration can be done by three different ways first one is torque ripple minimization and second one least square optimization and the third one is dead beat control.
Torque ripple which is used to calculate the optimal weighting factor and the control period is divided into two intervals to achieve further torque ripple reduction. The equation to obtain the optimal weighting factor is complicated and parameter dependent. The principle of torque ripple minimization is employed to calculate the duration of the active vector and a fixed weighting factor is used.
Although better steady-state performance than conventional MPTC is claimed, the results are obtained under the same sampling frequency as that of conventional MPTC. Furthermore, the active vector selection is first executed and then its duration is calculated. This cascaded processing leads to relative poor low -speed performance. Sensor nodes in such networks double as multi-hop relays and therefore we need a routing mechanism to convey sensed information.
For sparse sensor networks with a low duty cycle , the probability of having an end-to-end path is prohibitively low. This not only results in inadequate delivery ratios when single-path traditional connected routing protocols and their variants are used, but also handicaps the dissemination of control information in such protocols e.
On the other hand when the sensor network is dense, or if the duty cycle is sufficiently high, connected routing may be sufficient and fixed-replication multi-path routing may be detrimentally wasteful of bandwidth. Other exam- ples of variably intermittent networks include MANETs with highly mobile nodes, vehicular networks on a highway etc. Sensor nodes in such networks double as multi-hop relays, and therefore we need a routing mechanism to convey sensed information.
This not only results in inadequate delivery ra- tios when single-path traditional connected routing protocols and their variants are used, but also handicaps the dissemination of control information in such protocols e. On the other hand when the sensor network is dense, or if the duty cycle is sufficiently high, connected routing may be sufficient and fixed-replication multi-path routing may be detrimentally waste- ful of bandwidth.
Other examples of variably intermittent net- works include MANETs with highly mobile nodes, vehicular net- works on a highway etc. In such challenging dynamic environment, traditional routing and layered infrastructure are inefficient and sometimes even infeasible.
In recent research works, the opportunistic routing paradigm which delays the forwarding decision until reception of pack- ets in forwarders by utilizing the broadcast nature of the wireless medium has been exploited to overcome the limitations of traditional routing.
However, to guarantee the balance between the energy, delay and reliability requires the refinement of opportunistic routing through interaction between underlying layers known as cross-layer opportunistic routing. Indeed, these schemes fail to achieve optimal performance and hence require a new method to facilitate the adoption of the routing protocol to the dynamic challenging environments. In this paper, we propose a universal cross-layered opportunistic based communication protocol for WSNs for guaranteeing the user set constraints on multi-constrained QoS in low - duty - cycle WSN.
Therefore, both the current and the rate of change of current can be controlled. The two phase supply duration is limited by the two phase commutation angles. The main advantage of the PWM strategy is that the chopping frequency is a fixed parameter; hence, acoustic and electromagnetic noises are relatively easy to filter.
There are also two ways of handling the drive current switching: hard chopping and soft chopping. In the hard chopping technique, both phase transistors are driven by the same pulsed signal: the two transistors are switched-on and switched-off at the same time. The soft chopping approach allows not only a control of the current and of the rate of change of the current but a minimization of the current ripple as well.
In this soft chopping mode, the low side transistor is left ON during the phase supply and the high side transistor switches according to the pulsed signal. In this case, the power electronics board has to handle six PWM signals.
The duty cycle determines the speed of the motor. The desired speed can be obtained by changing the duty cycle. Modeling and Analysis of a Maximum Power Point Tracking Control for Double Stage Solar Photovoltaic Grid Connected Systems FLC is gaining importance in MPPT applications, as it is an intense strategy for reasoning and to handle non-linearity, when it is hard to express the determined conduct of the system as far as scientific model are in systematic equation and input information are uncertain.
To come across this demand, more effective systems are required. For satisfying this quicker and more efficient scheme such as microcontrollers, data processors etc are required. These plan works under very small voltages.
This interleaved DC-DC converter provides high current and low voltage at its output. Meanwhile interleaving approach is used here because the voltage ripples at the output terminals is reduced with the improvement of the ICs and the size of the devices is compact day by day.
So that the value of capacitor and inductor is reduced and also compact in size. In conventional DC-DC buck converter, particularly low duty cycle is essential for attaining low output voltage which rises the value of capacitor and inductor used . In this paper the proposed DC-DC converter reduces the input current and difficulty also reduced. In-stead of four switches only two switches are there.
Thus the control difficulty is reduced. Finally, the difference of output voltage ripple with dissimilar frequencies are evaluated.
This converter gives a constant dc bus voltage and its duty cycle is controlled by the MPPT controller. To maintain the power quality a feedback control is used. The complete system is designed, and modeled to evaluate its performance.
Simulated results are presented to demonstrate the performance of the MPPT controller and designed system for varying atmosphere conditions and load disturbances. This high step-up converter has finds its applications, in electric vehicles, uninterrupted power supplies UPS , high-intensity- discharge HID lamp, fuel cell system, and photovoltaic systems.
Vol 4, No 3 Many control strategies have been developed to control the speed of an induction motor by controlling the conduction angle of a thyristor or its duty cycle for an integral number of circles of the applied waveform, In general, almost all the popular methods of controlling the conduction time of a thyrstor using electronic devices are nothing but variations of either the Phase Angle firing control PFC or the Pulse Width Modulation firing control PWM.
The phase angle firing control is the most popular method of speed control. It is cheap and reliable, but torque is low at reduced voltages and the motor may stall on load or not start at all. The Pulse width modulation firing control is, however, perhaps by far, the most effective method of speed control.
Pulse width modulation allows us to have control over the percentage ON and OFF duty cycle of the applied voltage. It is effective and very efficient, and can be used on all types of load, but it is relatively more sophisticated and costly.
With PWM, the speed control of an induction motor has been shown to be more than a match for DC drives and is being applied almost everywhere where only DC drives were previously used. Low cost all digital duty cycle corrector To improve the delay line resolution, the FDL is added. The FDL is composed of two parallel connected tristate buffer arrays operating as an interpolator circuit. The propagation delay of the FDLis controlled by the driving strength of two parallel connected tristate buffer arrays.
Since MPPT can notably boost solar energy extraction of a photovoltaic PV system, the longer insolation period means that MPPT is more often operated to allow a smaller solar array while managing the same amount of load. Two assumptions are made to simplify the analysis: 1 load power is assumed to be constant and 2 battery over discharge is ignored because PV arrays and batteries are typically oversized in satellites to provide safety margins . Vol 6, No 1 The technical information and data used for the prototyping optimal PID-based control system, are summarized in Table 1 provided above.
Important issues to be considered in designing the MPPT algorithms include the complexity of the system, dynamical performance, and uncertainty. This paper introduces a two-level adaptive control architecture that can reduce complexity in the system control and efficiently handle the uncertainties and perturbations in the PV systems and in the environment.
This paper focuses mainly on the design of the MRAC algorithm, which improves the underdamped dynamic response of a PV system. Using an optimal law of the controller derived from the extended state-dependent Riccati equation. Study on Solar Power Charging by Flyback Converter current feedback circuit is added for better system stability. Vol 7, No 1 SDCS based on periodic scheduled wake up scheduled for data exchange which consists of the sleep period and an active period. Sensor node can communicate with each other when it in active mode otherwise in sleep mode radio of sensor node is off so they cannot communicate with each other.
This approach reduces the idle listening time of the sensor nodes which leads to reduce the energy consumption of the sensor nodes and increases the lifespan of the network. Thus, scheme introduces coordinate sleep scheduled of all nodes to maintain the network level connectivity. The drawback of SDCS is that it increases the sleep latency in multi hope network. So when traffic load is more, it increase number of queue packets due to sleep latency.
Many packets dropped due to buffered overflow which increases end to end latency of node. The end to end latency is inversely proportional to throughput. In WSN nodes generally deployed in different location requires different duty cycle to minimize the energy consumption and to increase the lifespan of network. For example, consider the parking system monitoring in malls, they continuously monitors the parked vehicles and data is continuously send to the from leaf node to sink or control system to observed the capacity of the parking place.
So nodes deploy near sink needs to transfer the more data than leaf node. Which gives nodes deploy near the sink required different duty cycle according to traffic conditions.
Dynamic duty cycle scheduling scheme are proposed to overcome these problems and to increase the energy conservation over the network. The advantage of this connection is having the ability to control how many SHEs are toggling or stopped inside the SHC using a single control signal and hence, controlling the amount of heat generated from that SHC.
This process is explained next. A new fuzzy-based maximum power point tracker for photovoltaic applications Our extensive measurements indicate that the amount of increase in PV output power highly depends on the environmental conditions and the load level. Note that the transient responses are not measured and only their computed waveforms are shown.
The main characteristics of the fabricated prototype are presented in Table II. The presented structure converts 29V input voltage to V in the output.
The switching frequency of the converter is chosen to be 50kHz. Therefore, the size of passive components is reduced. Ultrafast rectifiers with low forward voltage drop are utilized as power diodes. Improved junction temperature measurement for high power LED In the calibration step, the effect of duty cycle to the peak wavelength and forward voltage are shown in Figure The peak wavelength and forward voltage are slightly different at every duty cycle since higher heat dissipation is produced at higher duty cycle and causes junction temperature slightly increase.
The result shows that peak wavelength increases linearly with the increase of junction temperature, while forward voltage decreases with the increase of junction temperature. This topology is symmetric with a high boost factor in the low duty cycle and high modulation index, the low voltage stress on the capacitors, and the low current of the inductors and the input source.
In addition, the current of all inductors and the input current are equal, and the voltage across all the inductors, as well as the voltage across all diodes, are equal. Related subjects.
Wireless sensor network
Wireless sensor network WSN refers to a group of spatially dispersed and dedicated sensors for monitoring and recording the physical conditions of the environment and organizing the collected data at a central location. WSNs measure environmental conditions like temperature, sound, pollution levels, humidity, wind, and so on. These are similar to wireless ad hoc networks in the sense that they rely on wireless connectivity and spontaneous formation of networks so that sensor data can be transported wirelessly. WSNs are spatially distributed autonomous sensors to monitor physical or environmental conditions, such as temperature , sound , pressure , etc. The more modern networks are bi-directional, both collecting data from distributed sensors  and enabling control of sensor activity.
Metrics details. The last decades have been really hungry in new ways to reduce energy consumption. That is especially true when talking about wireless sensor networks in general and home multimedia networks in particular, since electrical energy consumption is the bottleneck of the network. One of the most energy-consuming functional block of an equipment is the radio front end, and methods to switch it off during the time intervals where it is not active must be implemented. This paper proposes a wake-up radio circuit which is capable of both addressing and waking up not only a more efficient but also more energy-consuming radio front end. By using a frequency footprint to differentiate each sensor, awaking all the sensors except for the one of interest is avoided. The particularity of the proposed wake-up receiver is that the decision is taken in the radio-frequency part and no baseband treatment is needed.
Wireless sensor network
There has been an increase in research interest in wireless sensor networks WSNs as a result of the potential for their widespread use in many different areas like home automation, security, environmental monitoring, and many more. Despite the successes gained, the widespread adoption of WSNs particularly in remote and inaccessible places where their use is most beneficial is hampered by the major challenge of limited energy, being in most instances battery powered. To prolong the lifetime for these energy hungry sensor nodes, energy management schemes have been proposed in the literature to keep the sensor nodes alive making the network more operational and efficient. Currently, emphasis has been placed on energy harvesting, energy transfer, and energy conservation methods as the primary means of maintaining the network lifetime. These energy management techniques are designed to balance the energy in the overall network.
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Приготовиться. Приступайте. - Мы не успеем! - крикнула Соши. - На это уйдет полчаса. К тому времени все уже рухнет.
Однако номер пока не удалось узнать. - Двести два. Где это? - Где же на необъятных американских просторах прячется эта загадочная Северная Дакота.
Когда Хейл перестал на нее давить, Сьюзан почувствовала, что ее онемевшие ноги ожили. Еще толком не отдавая себе отчета в своих действиях и повинуясь инстинкту, она резким движением согнула ноги и со всей силы ударила Хейла коленом в промежность, ощутив, как ее коленные чашечки впились в его мягкие незащищенные ткани. Хейл взвыл от боли, и все его тело сразу же обмякло. Он скатился набок, сжавшись в клубок, а Сьюзан, высвободившись из-под него, направилась к двери, отлично понимая, что у нее не хватит сил ее открыть.
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