scholarly journals Joint Bandwidth and Power Allocation for LTE-Based Cognitive Radio Network Based on Buffer Occupancy

2016 ◽  
Vol 2016 ◽  
pp. 1-23
Author(s):  
Alia Asheralieva ◽  
Yoshikazu Miyanaga
Keyword(s):  
Spectrum Sharing ◽  
Operating Conditions ◽  
Superior Performance ◽  
Network Resources ◽  
Minimal Impact ◽  
Available Bandwidth ◽  
Buffer Occupancy ◽  
Qos Guarantees ◽  
Network Usage

We investigate the problem of resource allocation in a cognitive long-term evolution (LTE) network, where the available bandwidth resources are shared among the primary (licensed) users (PUs) and secondary (unlicensed) users (SUs). Under such spectrum sharing conditions, the transmission of the SUs should have minimal impact on quality of service (QoS) and operating conditions of the PUs. To achieve this goal, we propose to assign the network resources based on the buffer sizes of the PUs and SUs in the uplink (UL) and downlink (DL) directions. To ensure that the QoS requirements of the PUs are satisfied, we enforce some upper bound on the size of their buffers considering two network usage scenarios. In the first scenario, PUs pay full price for accessing the spectrum and get full QoS protection; the SUs access the network for free and are served on a best-effort basis. In the second scenario, PUs pay less in exchange for sharing the bandwidth and get the reduced QoS guarantees; SUs pay some price for their access without any QoS guarantees. Performance of the algorithms proposed in the paper is evaluated using simulations in OPNET environment. The algorithms show superior performance when compared with other relevant techniques.

scholarly journals Buffer-based rate adaptation scheme for HTTP video streaming with consistent quality

2021 ◽  
pp. 21-21
Author(s):  
Jiwoo Park ◽  
Minsu Kim ◽  
Kwangsue Chung
Keyword(s):  
Queueing System ◽  
Video Quality ◽  
Rate Adaptation ◽  
Network Resources ◽  
Available Bandwidth ◽  
Buffer Occupancy ◽  
Network Bandwidth ◽  
Hypertext Transfer Protocol ◽  
The Difference ◽  
Adaptation Scheme

Recently, HyperText Transfer Protocol (HTTP) based adaptive streaming (HAS) has been proposed as a solution for efficient use of network resources. HAS performs rate adaptation that adjusts the video quality according to the network conditions. The conventional approaches for rate adaptation involve accurately estimating the available bandwidth or exploiting the playback buffer in HAS clients rather than estimating the network bandwidth. In this paper, we present a playback buffer model for rate adaptation and propose a new buffer-based rate adaptation scheme. First, we model the playback buffer as a queueing system that stores video segments. The proposed scheme selects the next video bitrate that minimizes the difference between the current buffer occupancy and the expected value from the playback buffer model. The evaluation results indicated that the proposed scheme achieves higher video quality than conventional algorithms and can cope with various environments without the tuning of the configuration parameters.

Research on the Economic Organization Environmental Impact

2017 ◽  
Vol 68 (3) ◽  
pp. 599-601
Author(s):  
Dan Paul Stefanescu ◽  
Oana Roxana Chivu ◽  
Claudiu Babis ◽  
Augustin Semenescu ◽  
Alina Gligor
Keyword(s):  
Economic Activity ◽  
Economic Organization ◽  
Economic Activities ◽  
Environmental Implications ◽  
Minimal Impact ◽  
Wide Range ◽  
Material Environment ◽  
Negative Effect ◽  
Harmful Effects

Any economic activity carried out by an organization, can generate a wide range of environmental implications. Particularly important, must be considered the activities that have a significant negative effect on the environment, meaning those which pollute. Being known the harmful effects of pollution on the human health, the paper presents two models of utmost importance, one of the material environment-economy interactions balance and the other of the material flows between environmental factors and socio-economic activities. The study of these models enable specific conditions that must be satisfied for the economic processes friendly coexist to the environment for long term, meaning to have a minimal impact in that the residues resulting from the economic activity of the organization to be as less harmful to the environment.

Measuring Long Term Superior Performance: Or How to Compare Apples with Oranges

2008 ◽  
Author(s):  
George S. Yip ◽  
Timothy M. Devinney ◽  
Gerry Johnson
Keyword(s):  
Superior Performance

Optimization of a decellularization protocol of porcine tracheas. Long-term effects of cryopreservation. A histological study

2021 ◽  
pp. 039139882110089
Author(s):  
Lara Milian ◽  
María Sancho-Tello ◽  
Joan Roig-Soriano ◽  
Giovanna Foschini ◽  
Néstor J Martínez-Hernández ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Histological Study ◽  
Biomechanical Properties ◽  
Elastic Fibers ◽  
Appreciable Effect ◽  
Long Term Effects ◽  
Minimal Impact ◽  
Biomechanical Effect ◽  
Triton X

Objective: The aim of this study was to optimize a decellularization protocol in the trachea of Sus scrofa domestica (pig) as well as to study the effects of long-term cryopreservation on the extracellular matrix of decellularized tracheas. Methods: Porcine tracheas were decellularized using Triton X-100, SDC, and SDS alone or in combination. The effect of these detergents on the extracellular matrix characteristics of decellularized porcine tracheas was evaluated at the histological, biomechanical, and biocompatibility level. Morphometric approaches were used to estimate the effect of detergents on the collagen and elastic fibers content as well as on the removal of chondrocytes from decellularized organs. Moreover, the long-term structural, ultrastructural, and biomechanical effect of cryopreservation of decellularized tracheas were also estimated. Results: Two percent SDS was the most effective detergent tested concerning cell removal and preservation of the histological and biomechanical properties of the tracheal wall. However, long-term cryopreservation had no an appreciable effect on the structure, ultrastructure, and biomechanics of decellularized tracheal rings. Conclusion: The results presented here reinforce the use of SDS as a valuable decellularizing agent for porcine tracheas. Furthermore, a cryogenic preservation protocol is described, which has minimal impact on the histological and biomechanical properties of decellularized porcine tracheas.

scholarly journals Intelligent long-term performance analysis in power electronics systems

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Saeed Peyghami ◽  
Tomislav Dragicevic ◽  
Frede Blaabjerg
Keyword(s):  
Performance Indicator ◽  
Thermal Characteristics ◽  
Operating Conditions ◽  
System Level ◽  
Power Electronic ◽  
Reliability Modeling ◽  
Artificial Neural Network Ann ◽  
Long Term Performance ◽  
Term Performance

AbstractThis paper proposes a long-term performance indicator for power electronic converters based on their reliability. The converter reliability is represented by the proposed constant lifetime curves, which have been developed using Artificial Neural Network (ANN) under different operating conditions. Unlike the state-of-the-art theoretical reliability modeling approaches, which employ detailed electro-thermal characteristics and lifetime models of converter components, the proposed method provides a nonparametric surrogate model of the converter based on limited non-linear data from theoretical reliability analysis. The proposed approach can quickly predict the converter lifetime under given operating conditions without a further need for extended, time-consuming electro-thermal analysis. Moreover, the proposed lifetime curves can present the long-term performance of converters facilitating optimal system-level design for reliability, reliable operation and maintenance planning in power electronic systems. Numerical case studies evaluate the effectiveness of the proposed reliability modeling approach.

Ni-based bimetallic nano-catalysts anchored on BaZr0.4Ce0.4Y0.1Yb0.1O3−δ for internal steam reforming of methane in a low-temperature proton-conducting ceramic fuel cell

2021 ◽  
Author(s):  
Kyungpyo Hong ◽  
Stephanie Nadya Sutanto ◽  
Jeong A. Lee ◽  
Jongsup Hong
Keyword(s):  
Steam Reforming ◽  
Low Temperatures ◽  
Operating Conditions ◽  
Hydrogen Yield ◽  
Carbon Formation ◽  
Long Term Stability ◽  
Ceramic Fuel Cell ◽  
Ceramic Fuel ◽  
Nano Catalysts

Ni–Rh and Ni–Co nano-scale alloys exhibit high methane conversion, hydrogen yield, resistance to carbon formation, and long-term stability at low temperatures, allowing them to cope with the various operating conditions of direct methane-fueled PCFCs.

Efficient Analysis of a Catenary Riser

2006 ◽  
Author(s):  
Elizabeth Passano ◽  
Carl M. Larsen
Keyword(s):  
Operating Conditions ◽  
Stochastic Simulations ◽  
Worst Case ◽  
Nonlinear Structure ◽  
Tension Response ◽  
Extreme Response ◽  
Analysis Strategies ◽  
Low Tension ◽  
Term Response

The paper deals with the challenge of predicting the extreme response of catenary risers, a topic of both industry and academic interest. Large heave motions introduced at the upper end of a catenary riser can lead to compression and large bending moments in the region immediately above the touch down area. In the worst case, dynamic beam buckling may occur. The focus of the paper will be on understanding the riser behaviour in extreme, low-tension response and in establishing suitable analysis strategies to predict the extreme response. Results from long nonlinear stochastic simulations of many sea states with varying environmental and operating conditions may be combined to describe the long-term response of a nonlinear structure such as a catenary riser. However, this theoretically straight-forward approach is very demanding computationally and ways to limit the extent of nonlinear stochastic simulations are therefore sought. The usefulness of simpler methods such as regular wave analysis to improve understanding of the physical behaviour and to aid in concentrating the nonlinear simulations to where they are most useful, will be demonstrated.

Effects of the Rolling Directions on Wear of the Aluminum Alloys

2021 ◽  
Vol 901 ◽  
pp. 193-198
Author(s):  
Yuh Ping Chang ◽  
Li Ming Chu ◽  
Chien Te Liu ◽  
Jin Chi Wang ◽  
Gao Wei Chen
Keyword(s):  
Wear Resistance ◽  
Aluminum Alloys ◽  
Rolling Direction ◽  
Optical Microscope ◽  
Operating Conditions ◽  
Crystal Phase ◽  
Transportation Industry ◽  
Key Technology ◽  
Crystal Grains

Due to the booming development of the automation industry and the transportation industry, the mechanical components are prone to wear under long-term operating conditions. To improve the wear resistance, effects of the rolling directions on wear of the aluminum alloys are studied. An optical microscope is used to analyze the crystal phase, and the correlation between the crystal grains and the rolling direction is studied. This study can therefore establish a key technology for improving the wear resistance of aluminum alloys.

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