A framework for describing correlated excitation of solar p modes

In a previous paper we suggested that, for a given p mode, the excitation function is the same as the component of the solar background noise that has an identical surface spherical harmonic projection (over the corresponding range of temporal frequency). An important consequence of this surmise is that the excitation of overtones of a given angular degree and azimuthal order will be correlated in time. In this note, we introduce the basic principles and a mathematical description of correlated mode excitation. We use simple, illustrative examples, involving two modes. Our treatment suggests that in the real observations, any signatures of the correlation would not appear as a correlation of the output amplitudes of overtones, but rather as subtle modifications to the power spectral density at frequencies between the central frequencies of the overtones. These modifications give a contribution to the observed peak asymmetries.Comment: 7 pages; accepted for publication in Astronomische Nachrichte

QoS Driven Routing Protocol in VANETs

Vehicular Ad Hoc Networks (VANETs) arespecial type of Mobile Ad hoc NETworks (MANETs). It is an effective new technology to forward packets or sharing messages between vehicles (V2V) or vehicle to infrastructure (V2I). VANETs are considered as one of the most emerging technologies for enhancing the efficiency and the safety applications of transportation systems. The main use of VANET is to exchange traffic related information between the vehicles and prevention of accidents in transportation system. In VANETs vehicles move with the high mobility so it can be considered as the major concern. The challenge in VANETs applications is to send the Emergency Message (EM) to all the vehicles which are available in the communication range. But, because of the wireless communication medium, sharing of the packets and broadcasting of traffic information may lead to frequent altercation and collision, this problem called "broadcast overhead problem". In this paper, a QoS driven protocol is proposed to utilize the network bandwidth efficiently by reducing the broadcast overhead and forwarding the urgent or emergency messages first compared to other messages. This new protocol first finds the Minimum Connected Dominating Set of Vehicle (MCDSV) to reduce the broadcast overhead and the MCDSV acts as a virtual backbone for communication within the Network. After finding the MCDSV, we use the concept of a priority Queue for emergency broadcast scheme (VDEB) to resolve the issue of high overhead in senderoriented schemes and long delay in receiveroriented schemes. For the safety applications the broadcast protocol has to guarantee the performance and the reliability context. This combined method of Minimum Connected Dominating Set and Priority Queue demonstrate the good performances and the robustness of such protocol compared to other Routing protocols

A Survey on Topology and Position Based Routing Protocols in Vehicular Ad hoc Network (VANET)

Vehicular Ad Hoc Networks (VANET) is a subclass of Mobile ad hoc networks. It is a developing new technology in which vehicles interchange the information from one vehicle to another vehicle within a network. VANET is responsible for providing an illustrated approach for Intelligent Transport System (ITS). The main use of VANET is to save life and prevent the accidents. This Paper describes a survey of routing protocols in vehicular ad hoc networks. The survey of routing protocols in VANET is significant and essential for smart ITS. The routing protocols are divided into two categories of topology-based and position-based routing for VANETs. This review discusses the advantages and disadvantages of these routing protocols

Stochastic R-Tuple Estimation for Unicast Routing Protocol in VANET

Vehicular Ad hoc NETwork (VANET) is a latest technology that enables vehicles to communicate with infrastructure and with vehicle. It comes under the sub class of Mobile Ad hoc NETwork (MANET). In VANET all participating nodes are highly moving. VANET has two type of communication vehicle to infrastructure (V2I) and vehicle to vehicle (V2V). Each vehicle equipped with on board unit (OBUs) that gives the service of communicating with road side unit (RSUs). Main motivation behind VANET is to provide safety from accident and avoid the accident To manage the traffic VANETs play an important role for Intelligent Transportation Systems (ITS). VANET has high mobility compare to MANET. Due to high mobility, routing is biggest challenge. In this paper, reliability tuple estimation protocol (RTEP) is proposed for unicast routing protocol in VANET. R-Tuple plays a vital role in selecting reliable route between source and target vehicle. R-Tuple has three parameter range, direction and speed of the vehicle. Reliable route is selected based on these parameters

Lightning phenomena and its effect on transmission line

As we know that Lightning is one of the most natural and serious cause of over voltage .So, my this paper describes about the lightning phenomena, the way it is caused and in the manner it effects the power equipments, building frames, transmission lines, etc It is matter of great surprise to know that over the whole world ,more than 40,000 lightning strokes per day and less than 100 lightning strokes per second takes place. Transmission lines functions as arteries that carry electricity from power stations to regions where the power is needed. Therefore, it is vital to control the construction and maintenance costs of these lines because while the frequency of transmission line faults resulting in power loss has decreased year by year yet the trouble due to natural cause lightning is not yet reduced The main object of this paper is to study the effect of lightning strokes on transmission lines which cause great damage due to traveling waves to the electrical equipments installed in open air and insulators, etc. Frequently lightning problems do not receive consideration during the design stage. It remains then for the lightning safety engineer to analyze the effect of thelightning during operations and to provide rational for safety  through modification to the Assets, Facilities and Structures

The disturbances in the power system due to environmental conditions

In most of our electronics and electrical devices are very sensitive to the real voltage and current values and other parameters. A slight fluctuation in the voltage and in the current may damage the devices. Therefore proper care needs to be taken for the proper functioning of these devices. But at the same time we cannot neglect the effect of environmental conditions on the devices used in the power system. The environmental conditions such as rainfall, heat, wind, humidity, thundering and lightning etc. has a significant influence on various electrical parameters and also even in the transmission lines. Taking the various environmental conditions into the account the efficiency and the reliability to the devices and the power system can improved

Optimal Location of Distributed Generation and its Impacts on Voltage Stability

Distributed generation (DG) technology is based on the renewable sources of energy. Now a day’s distributed generation plays an important role of power generation utilities to fulfill the increasing demand of power at the costumer’s site. A distributed generation is the small generation unit with capacity varying from kW (kilowatt) to few MW (megawatt). The main aim of this paper is to find the solution for optimal location of connecting DG and also the disturbances in the voltage fluctuations responds to imperfection of connecting DG. A test network of IEEE-30 bus system has been simulated using PSAT 2.1.7. The compensation methods have also been developed for filtering out the disturbances caused by the DG connection. The disturbance in the voltage profile is improved by minimizing the real and reactive power losses with the help of STATCOM. The proposed approach IEEE-30-bus system was tested and the result was discussed