Complete Energy Model Research Articles

Access Control for IoT Nodes With Energy and Fidelity Constraints

The presence of many battery-powered sensors in the Internet of Things paradigm calls for the design of energy-aware protocols. Source coding techniques make it possible to save some energy by compressing the packets sent over the network, but at the cost of poorer accuracy in the representation of the data. This paper addresses the problem of designing efficient policies to jointly perform processing and transmission tasks. In particular, we aim at defining a scheduling strategy with the twofold goal of extending the network lifetime and guaranteeing a low overall distortion of the transmitted data. We propose a time division multiple access-based access scheme that efficiently allocates resources to heterogeneous nodes. We use realistic rate-distortion curves to quantify the impact of compression on the data quality and propose a complete energy model that includes the energy spent for processing and transmitting the data, as well as the circuitry energy costs. We consider both full and statistical knowledge of the wireless channels and derive communication policies for the two cases. The overall problem is structured in modules and solved through convex and alternate programming techniques. Finally, we thoroughly evaluate the proposed algorithms and the influence of the design variables on the system performance adopting parameters taken from real sensors.

Numerical analysis of formation properties of a high-field dipole domain for submicron GaAs field-effect transistor devices

A typical 0.3-μm gate-length submicron GaAs metal-semiconductor field-effect transistor (MESFET) is simulated using a complete energy model that solves a complete form of the energy conservation equation, and also using a simplified energy model that only neglects heat flux for electrons. The simulations are carried out with the same device physical and bias conditions, and a transient analysis is made to investigate thermal electron conduction effects on the formation property of a high-field dipole domain in the submicron GaAs MESFET. It is shown that the simplified model leads to the existence of a very unstable Gunn domain oscillating between the gate and drain, but the more accurate complete model gives a stable high-field domain confined well in the gate region due to thermal electron conduction. The crucial reason for this discrepancy between the two results is associated with the capable limits of accuracy in the simplified model. That is, this model gives rise to an unduly large retardation in the energy-gaining rate of electrons in the gate channel, so that the production of the negative differential resistance phenomenon by the electrons is largely delayed under the gate. Therefore, a traveling Gunn domain can be exhibited for submicron GaAs field-effect transistors in the simulation by a simplified energy model. It is demonstrated that even though simplified energy models are capable of reflecting the nonstationary effect of velocity overshoot properly, it is quite improper to apply these for studying device physics related to dipole domain properties; thermal electron conduction plays a pivotal role in forming a stable dipole domain in the submicron GaAs MESFET. In addition, the average effective valley-transition force for channel electrons (a new physical quantity first defined in the paper) is used to show that simplified energy models give a much larger magnitude for the force (approximately 1.8 eV/μm) compared to 1.2 eV/μm given by the complete energy model. Furthermore, the force is given closer to the drain end of the gate in the former models. Therefore, simplified energy models have a high possibility of creating a traveling domain for submicron devices.

Optimizing sensor movement planning for energy efficiency

Conserving the energy for motion is an important yet not-well-addressed problem in mobile sensor networks. In this article, we study the problem of optimizing sensor movement for energy efficiency. We adopt a complete energy model to characterize the entire energy consumption in movement. Based on the model, we propose an optimal trapezoidal velocity schedule for minimizing energy consumption when the road condition is uniform; and a corresponding velocity schedule for the variable road condition by using continuous-state dynamic programming. Considering the variety in motion hardware, we also design one velocity schedule for simple microcontrollers, and one velocity schedule for relatively complex microcontrollers, respectively. Simulation results show that our velocity planning may have significant impact on energy conservation.

Energy flow analysis for curved beams

This paper presents an energy model for the medium- and high-frequency analysis of Love–Kirchhoff curved beams. This model introduced by Nefske and Sung [Statistical Energy Analysis NCA 3, 47–54 (1987)] for straight beams and investigated further by other authors, is developed for curved rods (tangential or longitudinal waves), and then for curved beams (radial or flexural waves). The exact-energy solution for curved rods or beams is shown to consist of a smooth spatial variation, which the energy model represents, and a spatially oscillating solution, which can be represented by an energy envelope. Finally, a complete energy model is proposed for curved components including both longitudinal and flexural waves. Boundary conditions are also given in this paper. It is shown that this method, which is numerically attractive in the mid- and high-frequency range, predicts the arithmetic mean value of the energy variables.