Energy Management Policies for Energy-Neutral Source-Channel Coding

In cyber-physical systems where sensors measure the temporal evolution of a given phenomenon of interest and radio communication takes place over short distances, the energy spent for source acquisition and compression may be comparable with that used for transmission. Additionally, in order to avoid limited lifetime issues, sensors may be powered via energy harvesting and thus collect all the energy they need from the environment. This work addresses the problem of energy allocation over source acquisition/compression and transmission for energy-harvesting sensors. At first, focusing on a single-sensor, energy management policies are identified that guarantee a maximal average distortion while at the same time ensuring the stability of the queue connecting source and channel encoders. It is shown that the identified class of policies is optimal in the sense that it stabilizes the queue whenever this is feasible by any other technique that satisfies the same average distortion constraint. Moreover, this class of policies performs an independent resource optimization for the source and channel encoders. Analog transmission techniques as well as suboptimal strategies that do not use the energy buffer (battery) or use it only for adapting either source or channel encoder energy allocation are also studied for performance comparison. The problem of optimizing the desired trade-off between average distortion and delay is then formulated and solved via dynamic programming tools. Finally, a system with multiple sensors is considered and time-division scheduling strategies are derived that are able to maintain the stability of all data queues and to meet the average distortion constraints at all sensors whenever it is feasible.Comment: Submitted to IEEE Transactions on Communications in March 2011; last update in July 201

Control apparatus for spectral energy source

Automatic light-controlling system for dc arc emission spectrographs controls the vaporization rate of the sample and stabilizes the dc arc. The output energy is regulated such that advantage can be taken of the highly sensitive dc arc source without sacrificing the desired precision

Pion LINAC as an Energy-Tagged Neutrino Source

The energy spectrum and flux of neutrinos from a linear pion accelerator are calculated analytically under the assumption of a uniform accelerating gradient. The energy of a neutrino from this source reacting in a detector can be determined from timing and event position information.Comment: 16 pages, 4 figures. Replacement of Section II.D and minor corrections elsewhere. The basic point and conclusions of the paper are unchanged. Phys. Rev. ST Accel. Beams 11,124701 (2008); Erratum submitte

Battery charging and discharging control of a hybrid energy system using microcontroller

This study aims to control charging and discharging the battery for hybrid energy systems. The control system works by selecting the right energy source to supply voltage to the load. And also this control system can regulate charging and discharging the battery automatically. The voltage source consists of two energy, namely from the battery and DC source. The control system that has been designed has the ability to choose the right DC source when the battery capacity is less than 80%. This system also has a good ability to choose a battery source when the battery reaches 100% capacity and the DC source has a voltage drop of more than 20%. This control system is equipped with excessive electric current protection so that the security level is high

Fermionic Tachyons as a Source of Dark Energy

A model for the universe on the basis of a self interacting fermionic tachyon field is investigated here. It is shown that, devising a self interaction potential of a proper form, the fermionic tachyon field is capable of producing an accelerating expansion that at late time tends to a constant value which is in consistence with the cosmological constant. This way the introduced fermionic tachyon field can be interpreted as the source of dark energy.Comment: 5 figure

Energy Minimization for the Half-Duplex Relay Channel with Decode-Forward Relaying

We analyze coding for energy efficiency in relay channels at a fixed source rate. We first propose a half-duplex decode-forward coding scheme for the Gaussian relay channel. We then derive three optimal sets of power allocation, which respectively minimize the network, the relay and the source energy consumption. These optimal power allocations are given in closed-form, which have so far remained implicit for maximum-rate schemes. Moreover, analysis shows that minimizing the network energy consumption at a given rate is not equivalent to maximizing the rate given energy, since it only covers part of all rates achievable by decode-forward. We thus combine the optimized schemes for network and relay energy consumptions into a generalized one, which then covers all achievable rates. This generalized scheme is not only energy-optimal for the desired source rate but also rate-optimal for the consumed energy. The results also give a detailed understanding of the power consumption regimes and allow a comprehensive description of the optimal message coding and resource allocation for each desired source rate and channel realization. Finally, we simulate the proposed schemes in a realistic environment, considering path-loss and shadowing as modelled in the 3GPP standard. Significant energy gain can be obtained over both direct and two-hop transmissions, particularly when the source is far from relay and destination.Comment: To appear on IEEE Trans. on Communication