Variations of the VLF-EM primary field: Analysis of airborne survey data, New Brunswick, Canada

Geophysics ◽  
1992 ◽  
Vol 57 (1) ◽  
pp. 181-186 ◽  
Author(s):  
Marc A. Vallée ◽  
Michel Chouteau ◽  
G. J. Palacky
Keyword(s):  
New Brunswick ◽  
Solar Flares ◽  
Base Station ◽  
Propagation Model ◽  
Field Analysis ◽  
Primary Field ◽  
Survey Area ◽  
Em Field ◽  
Airborne Survey

Variations in intensity of the primary VLF-EM field have a significant effect on the quality of airborne and ground surveys in which the total field is measured. An analysis of the results of a recent VLF-EM survey and base station records in New Brunswick, Canada, revealed major variations in the primary VLF-EM field due to changes in the transmitting power and to solar flares. To study the effect of systematic primary field variations over the survey area, VLF-EM field intensity was calculated using radio propagation model based on uniform conductive earth and anisotropic‐layered ionosphere. The model correctly predicted a decrease in the primary field generated by the NAA transmitter by about 40 percent in a direction perpendicular to a survey line. Such a change is sufficiently important to require repeated calibrations of the receiver between the survey lines. The model also indicated that the phase difference between contributions of the ground and sky waves should vary over the survey area. Such variations explain opposite polarities of sudden amplitude variations due to solar flares that were observed during the survey.

scholarly journals HATA Path Loss Model Optimization Using Particle Swarm Algorithm

2021 ◽  
Author(s):  
Deepti Kakkar ◽  
Ashish Prashar ◽  
Mehar Latif ◽  
Aitraiyee Konar ◽  
Kishan Kumar ◽  
...  
Keyword(s):  
Path Loss ◽  
Base Station ◽  
Propagation Model ◽  
Particle Swarm Algorithm ◽  
Model Optimization ◽  
Wireless System ◽  
Swarm Optimization ◽  
K Factor ◽  
Better Than

Fallacious path loss predictions before the placing of base station(BS) cause under evaluation of circulation areas which gives rise to unabating call drops & cross talks. The escalating demands of meeting overhaul needs of applications by users makes the consequence worst, which significantly influences competence of the cellular wireless system. Propagation model is a keystone of coverage planning. To slash cost, proper planning is needed in coverage of network in order to upgrade the quality of service. Now, K factor is taken into account in order to improve or enhance propagation model based on particles swarm optimization(PSO).The root mean square error(RMSE) between confirmed or verified measurements data & data we obtain from prediction model is used to test and validate the technique used. The values of the RMSE acquired by enhancedmodel and those attained by the standard Hata model are also juxtaposed. We reckoned that the model developed using PSO is better than the HATA model and is errorless.

scholarly journals Some indicators of water quality of the Tamis river

2011 ◽  
Vol 17 (1) ◽  
pp. 107-115 ◽  
Author(s):  
Nada Babovic ◽  
Dejan Markovic ◽  
Vojkan Dimitrijevic ◽  
Dragan Markovic
Keyword(s):  
Water Quality ◽  
Ph Value ◽  
Ammonium Nitrogen ◽  
Field Analysis ◽  
Total Hardness ◽  
Chemical Parameters ◽  
Physico Chemical

This paper shows the results obtained in field analysis performed at the Tamis River, starting from the settlement Jasa Tomic - border between Serbia and Romania to Pancevo - confluence of Tamis into the Danube. The Tamis is a 359 km long river rising in the southern Carpathian Mountains. It flows through the Banat region and flows into the Danube near Pancevo. During the years the water quality of the river has severely deteriorated and badly affected the environment and the river ecosystem. In situ measurements enabled determination of physico-chemical parameters of water quality of the Tamis River on every 400 m of the watercourse, such as: water temperature, pH value, electrical conductivity, contents of dissolved oxygen and oxygen saturation. The main reason of higher pollution of Tamis is seen in connection to DTD hydro system. Sampling was performed at 7 points with regard to color, turbidity, total hardness, alkalinity, concentration of ammonium nitrogen, nitrite nitrogen, nitrate nitrogen, iron, chlorides and sulphates in samples. The aim of the present work was to evaluate water quality in the Tamis River taking into account significant pollution, which originates from settlements, industry and agriculture, and to suggest appropriate preventive measures to further pollution decreasing of the river's water.

scholarly journals Joint power allocation and subcarrier assignment for device to device in 5G time division duplex networks

2018 ◽  
Vol 14 (11) ◽  
pp. 155014771881109 ◽  
Author(s):  
Pan Zhao ◽  
Lei Feng ◽  
Peng Yu ◽  
Wenjing Li ◽  
Xuesong Qiu
Keyword(s):  
Quality Of Service ◽  
Power Allocation ◽  
Base Station ◽  
Joint Power ◽  
Time Division Duplex ◽  
Device To Device ◽  
Minlp Problem ◽  
Device To Device Communication ◽  
Time Division

The explosive demands for mobile broadband service bring a major challenge to 5G wireless networks. Device-to-device communication, adopting side links for user-direct communication, is regarded as a main technical source for offloading large volume of mobile traffic from cellular base station. This article investigates the joint power and subcarrier allocation scheme for device-to-device communication in 5G time division duplex systems. In time division duplex system, instead of utilizing an exclusive portion of the precious cellular spectrum, device-to-device pairs reuse the subcarriers occupied by cellular users, thus producing harmful interference to cellular users in both uplink and downlink communication, and strongly limiting the spectrum efficiency of the system. To this end, we focus on the maximization of device-to-device throughput while guaranteeing both uplink and downlink channel quality of service of cellular users as well as device-to-device pairs. The problem is formulated as a mixed integer non-linear programming (MINLP) problem. To make it tractable, we separate the original MINLP problem into two sub problems: power allocation and sub-carrier reusing. The former is to develop optimal power allocation for each device-to-device pair and each cellular user, with the constraints of maximum power and quality of service. It is solved by geometric programming technique in convex optimization method. The latter is derived as a one-to-many matching problem for scheduling multiple subcarriers occupied by cellulars to device-to-device pairs. It is solved by Hungarian method. Simulation results show that the proposed scheme significantly improves system capacity of the device-to-device underlay network, with quality of service of both device-to-device users and cellular users guaranteed.

The Distribution of Rabbit Warrens at Mitchell, Queensland, in relation to Soil and Vegetation Characteristics

1976 ◽  
Vol 3 (2) ◽  
pp. 129 ◽  
Author(s):  
BS Parker ◽  
LS Hall ◽  
K Myers ◽  
PJ Fullagar
Keyword(s):  
Unit Area ◽  
Sandy Soils ◽  
Food Type ◽  
Survey Area ◽  
Late Afternoon ◽  
Transect Counts ◽  
Vegetation Characteristics ◽  
Selection For ◽  
Open Woodland

In a 42,750-ha survey area in subtropical Queensland, rabbit warrens are confined mainly to sandy soils. Within these favoured areas the population is distributed unevenly, and there is further selection for preferred habitats. Detailed studies on a 246-ha area of sandhill showed that the open woodland and grassy open woodland associations contain most warrens per unit area, and also the largest warrens. The quality of habitat for rabbits appears to be determined by availability of food, type of soil, and vegetation cover providing protection from predators. In some vegetation associations, use of burrows varies only slightly, in others there are significant changes. There is a significant correlation between the estimated numbers of rabbits in the population, the total number of rabbits seen on spotlight transect counts in the evening, the numbers of rabbits seen on warrens during late afternoon watches, and the total number of active burrow entrances present in the study area. A list of plant species present and a description of the 23 vegetation associations in the study area is presented.

scholarly journals Application of hybrid boundary element method: Example of semishperical ground inhomogeneity

2014 ◽  
Vol 11 (4) ◽  
pp. 617-628
Author(s):  
Nenad Cvetkovic ◽  
Sasa Ilic ◽  
Dragan Vuckovic ◽  
Dejan Jovanovic ◽  
Dejan Krstic
Keyword(s):  
Boundary Element Method ◽  
Point Source ◽  
Numerical Method ◽  
Boundary Element ◽  
Program Package ◽  
Image Theory ◽  
Field Analysis ◽  
Grounding System ◽  
Em Field ◽  
Element Method

One new, so-called hybrid boundary element method (HBEM) is presented in this paper. It is a recently proposed numerical method for stationary and quasi-stationary EM field analysis. The method application is illustrated on the example of solving the problem of modelling hemispherical ground inhomogeneity influence on grounding system. The applied procedure also includes using of quasi-stationary image-theory. The obtained results are compared with those ones based on using the Green?s function for the point source inside semi-spherical inhomogeneities as well as with the results obtained by applying COMSOL program package.

scholarly journals Performance of Base Stations in Railway Digital Radio Communication Networks

2021 ◽  
Vol 19 (2) ◽  
pp. 41-48
Author(s):  
Yu. V. Nemtsov ◽  
I. V. Seryogin ◽  
P. I. Volnov
Keyword(s):  
Communication Network ◽  
Communication Networks ◽  
Base Station ◽  
Base Stations ◽  
Radio Communication ◽  
Radio Communications ◽  
Digital Radio ◽  
Cargo Transportation ◽  
Assess Quality

Base station (BS) is a terminal device of a radio communication network, while railway radio communications play an important role in ensuring safety of passenger and cargo transportation.A proposed method for calculating the performance of base stations in railway digital radio communication networks is intended to calculate for the BS the probabilities of being in certain state.BS was decomposed and such functional elements as circuit groups and a radio frequency path were identified, as well as the central module ensuring the exchange of information with elements of this BS and with other BSs. A detailed study of each element has increased accuracy of the proposed method. Following the Markov model, BS is presented as a system in which all possible states are considered. Models for BS with two and three circuit groups have been constructed. The parameters of each functional element of the model can be obtained through observation over a certain period. The solution of the system of equations for each of the models presented in the article will allow obtaining the values of the system being in a certain state. The obtained characteristics can be used to calculate the reliability of the entire radio communication network, and then to assess quality of service provided to the users of this network.Conclusions are made about the possibilities of using the obtained models when designing new railway communication networks and when calculating quality indices of existing ones. The proposed models can be applied not only to railway radio communication networks but also to mobile communication networks of commercial operators. 

Novel materials for improved quality of RF-PA in base-station applications

2005 ◽  
Vol 28 (4) ◽  
pp. 644-649 ◽  
Author(s):  
Z. Radivojevic ◽  
K. Andersson ◽  
L. Bogod ◽  
M. Mahalingam ◽  
J. Rantala ◽  
...  
Keyword(s):  
Base Station ◽  
Novel Materials

A Game Theoretic Framework for Green HetNets Using D2D Traffic Offload and Renewable Energy Powered Base Stations

2017 ◽  
pp. 679-711
Author(s):  
Elias Yaacoub ◽  
Hakim Ghazzai ◽  
Mohamed-Slim Alouini
Keyword(s):  
Renewable Energy ◽  
Renewable Energy Sources ◽  
Nash Bargaining Solution ◽  
Base Station ◽  
Base Stations ◽  
Nash Bargaining ◽  
Bargaining Solution ◽  
Green Communications ◽  
Game Theoretic

This chapter investigates the interplay between cooperative device-to-device (D2D) communications and green communications in LTE heterogeneous networks (HetNets). Two game theoretic concepts are studied and analyzed in order to perform dynamic HetNet base station (BS) on/off switching. The first approach is a coalition-based method whereas the second is based on the Nash bargaining solution. Afterwards, a method for coupling the BS on/off switching approach with D2D collaborative communications is presented and shown to lead to increased energy efficiency. The savings are additionally increased when a portion of the small cell BSs in a HetNet are powered by renewable energy sources. Different utility functions, modeling the game theoretic framework governing the energy consumption balance between the cellular network and the mobile terminals (MTs), are proposed and compared, and their impact on MT quality of service (QoS) is analyzed.

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