Modified Mobility Model Research Articles

The Impact of Electric Vehicle on Road Transportation in Indonesia: Energy Demand and CO2 Emission

Light Duty Vehicle (LDV) for road transportation in Indonesia is the biggest energy consumption with most of the energy carriers from refined fuel oil with high CO2 emission. Battery Electric Vehicle (BEV) is one of the alternatives to reduce oil consumption and CO2 emission on the road transportation sector. This research is carried to analyse impact on BEV on energy demand and carbon emission. Modified Mobility Model (MoMo) with PUCE methods was developed to projecting road transportation demand in Indonesia. This research shows that road transportation will reach 519 MBoe in 2040 with 83.6% from refined fuel oil. With moderate EV, energy will be reduced by 31 MBoe (6%), and refined fuel oil reduced by 8.5%. With a high EV scenario, energy will be reduced by 57 MBoe (14%) and refined fuel oil reduced by 16%. CO2 emission will be reduced up to 4.8 to 8.8% in 2040.

Mobility-Aware Coded Probabilistic Caching Scheme for MEC-Enabled Small Cell Networks

Caching on the edge has been recognized as an effective solution to tackle the backhaul constraint of network densification. However, most related works ignored user mobility in wireless networks, which is unreasonable under the background of network densification. For a more flexible and context-aware caching decision, the concept of caching on the edge can be extended to mobile edge computing (MEC) that enables computation and storage resources at mobile edge networks. With MEC servers deployed on base stations, a huge amount of collected radio access network context data can be analyzed and utilized to render a caching scheme adaptive to user’s context-aware information. In this regard, a novel mobility-aware coded probabilistic caching scheme is proposed for MEC-enabled small cell networks (SCNs). Different from previous mobility-aware caching schemes, user mobility and distributed storage are incorporated into a conventional probabilistic caching scheme, with the aim of throughput maximization. Based on stochastic geometry theory and a modified mobility model of discrete random jumps, the explicit expression of throughput is derived. Due to the complexity of the expression, two light-weight heuristic algorithms are provided to numerically obtain the optimal solutions. Moreover, a significant trade-off among the gains of mobility diversity, content diversity, and channel selection diversity is discussed, and we further numerically analyze how such a trade-off is influenced by user mobility, content popularity, and backhaul capacity, with some fundamental insights into the application of the proposed scheme in MEC-enabled SCNs. The superiority of our proposed scheme is demonstrated by the comparisons with the classical M most popular caching scheme and the conventional probabilistic caching scheme. Numerical results show that our proposed caching scheme achieves higher throughput than those of the other two, especially when users of intense mobility request contents, of which the popularity profile is not skewed, in MEC-enabled SCNs with poor backhaul capacity, indicating that the proposed caching scheme is a promising solution for network densification.

Mobility degradation mechanisms of MOSFETs with a high-k dielectric layer.

The electrical characteristics of MOSFETs with a high-k dielectric layer were simulated by using a full three-dimensional technology computer-aided design simulator. The MOSFETs leakage current increased when their size decreased. The mobility variation mechanisms due to the polarization variation with the positive fixed charges in the high-k dielectric layer and with the negative trap charges in the SiO2 layer were clarified by using a modified mobility model of the universal model taking into account remote phonon scattering effects. The induced polarization in the high-k dielectric layer was dominantly attributed to the magnitude and the polarity of the charges in an interfacial layer. The mobility degradation was dominantly attributed to the polarization effects. The mobility values of the channel region in the MOSFETs, calculated by using the modified mobility model, were in reasonable agreement with their real mobility magnitudes. This result improves the enhancement of the electrical characteristic of the MOSFETs with a high-k layer.

Electron mobility in the linear region of an AlGaN/AlN/GaN heterostructure field-effect transistor

We simulate the current—voltage (I—V) characteristics of AlGaN/AlN/GaN heterostructure field-effect transistors (HFETs) with different gate lengths using the quasi-two-dimensional (quasi-2D) model. The calculation results obtained using the modified mobility model are found to accord well with the experimental data. By analyzing the variation of the electron mobility for the two-dimensional electron gas (2DEG) with the electric field in the linear region of the AlGaN/AlN/GaN HFET I—V output characteristics, it is found that the polarization Coulomb field scattering still plays an important role in the electron mobility of AlGaN/AlN/GaN HFETs at the higher drain voltage and channel electric field. As drain voltage and channel electric field increase, the 2DEG density reduces and the polarization Coulomb field scattering increases, as a result, the 2DEG electron mobility decreases.

VGSim: An integrated networking and microscopic vehicular mobility simulation platform

Simulation is the predominant tool used in research related to vehicular ad hoc networks. In this article we first present the key requirements for accurate simulations that arise from the various applications supported by VANETs, and review the current state-of the-art VANET simulation tools. We then present VGSim, an integrated networking and microscopic vehicular mobility simulation platform. VGSim provides full-fledged wireless network simulation with an accurate traffic mobility model. These two components are tightly integrated and can interact dynamically. We discuss the flexibility of VGSim in adopting different mobility models and also present simulation results that empirically validate the modified mobility model we implemented. We discuss how VANET applications can be easily modeled in VGSim, and demonstrate this using two important applications, Accident Alert and Variable Speed Limit.

Physical Analysis for Saturation Behavior of Hot-Carrier Degradation in Lightly Doped Drain N-Channel Metal-Oxide-Semiconductor Field Effect Transistors

This paper experimentally demonstrates that hot carrier degradation curves of lightly doped drain n-channel metal-oxide-semiconductor field effect transistors (LDDNMOSFETs) has universal behavior even if different stress conditions were applied. From this phenomena, we have proved that the Φ it/E m, the ratio of critical barrier for interface state generation to the maximum electric field, doesn't change so that accurate lifetime prediction for drain avalanche hot carrier (DAHC) is possible using conventional log (τI d) vs log (I sub/I d) method even if the degradation vs stress time curves show a saturation behavior. We have modeled stressed LDD as an equivalent circuit which is comprised by a surface channel MOSFET and two buried channel MOSFETs. And various circuit simulations were done by mobility change of drain side buried channel MOSFET. As a result, a modified mobility model with a lower limit parameter for mobility degradation has been developed, which successfully describes the saturation behavior of device degradation.

Sorption and diffusion of carbon dioxide in polyimide films

The sorption isotherms of carbon dioxide in a polyimide film sample were measured by a pressure decay method at 30, 40, 50, and 60°C and pressures up to 1.7 MPa. The mean permeability coefficients at the same temperatures were measured by a variable volume method at applied upstream pressures up to 3 MPa. The sorption equilibria at these temperatures were found to be well described in terms of a dual-mode sorption model. The pressure dependences of the mean permeability coefficients at these four levels of temperatures did not satisfactorily follow a dual-mode mobility model, but could be well simulated by a modified mobility model that both the Henry's law (D) and Langmuir (H) populations execute four kinds of diffusive movements such as D D, D H, H D, and H H. The diffusion coefficients of D D, D H, and combined H H and H D steps were determined by comparing the experimental permeability data with those predicted via this modified mobility model. The temperature dependences of such diffusion coefficients were consistent with Arrhenius-type equations within the covered temperatures.

Mechanism of gas permeation through glassy polymer films

The observed pressure dependence of the mean permeability coefficients of carbon dioxide and methane in glassy polymer films such as polycarbonate, Kapton® polyimide and polysulfone, taken from existing papers, was compared with the predictions in terms of a dual-mode mobility model and a modified mobility model in which both the Henry's Law and Langmuir populations execute four kinds of diffusive movement. The pressure dependence is simulated better by the modified model than by the original model. The mean permeability coefficients and sorption isotherms for carbon dioxide and methane in commercially available polysulfone films were measured at four temperature levels between 30 and 45°C and at gas pressures up to 33 atm and 61 atm, respectively. The pressure dependence of the mean permeability coefficients for the above systems is also described well by the modified mobility model, whereas the sorption isotherms are described well by the dual-mode sorption model.

Two-dimensional simulation of MODFET and GaAs gate heterojunction FET's

Previous simulation studies on heterojunction devices have been limited to idealized device structures (mostly 1-D) which neglect important parasitic effects. In order to realistically simulate heterojunction devices, a general two-dimensional device simulator has been developed which includes for the first time features essential to designing and modeling realistic devices, for example, multiple heterolayers, a modified mobility model for the 2-D electron gas, Fermi level pinning at the surfaces, and deep traps in the substrate. Two specific types of high electron mobility heterojunction devices have been studied and compared. The first type is the recessed-gate MODFET and the second type is the GaAs gate heterojunction FET. At 77 K, simulation results showed that high transconductances (450-500 mS/mm) can be obtained for both types of structures with similar geometries. For GaAs gate FET's, the device operation is found to be sensitive to the surface defect density in the ungated gap of the self-aligned T-gate structure, while for a similar MODFET structure with an analogous gap between the actual recessed edge and the gate edge, the dependency on the surface defect density is relatively weak because the AlGaAs layer is rather heavily doped. The causes for the transconductance degradation of MODFET's have been identified as either the neutralization of the ionized impurities in the AlGaAs layer or the saturated resistor under the ungated gap in the recessed region.