A.K. Gupta

Mobility management in heterogeneous wireless networks based on IEEE 802.21 framework

Wireless and mobile networks are evolving very rapidly. The mobile nodes in the wireless networks are having multiple interfaces with different radio access technologies (RATs) which are having different capabilities, cost and performance ratio. The use of non-PC based portable devices is increasing due to their flexible usage. The wireless and mobile network which is formed by these non-PC and PC based devices is heterogeneous in nature and these networks are co-located. Multiple interfaces can be included in the mobile device by using separate hardware and software modules. A mobile user wants to be Always Best Connected (ABC) as per its various requirements and availability in a particular environment. When a mobile node leaves the current network and joins the other network, a handover operation is needed and performed. The Handover operation is used to achieve seamless mobility and is of two types, first is in between same RATs and second is in between different RATs. For seamless and smooth handover operations across heterogeneous networks, IEEE has published a standard, named as IEEE 802.21. This paper presents a comprehensive description on the issues and challenges for achieving the seamless mobility in a heterogeneous environment. Apart from this, we also present the description of services provided by IEEE 802.21 standard and related vertical handover schemes to realize seamless mobility in heterogeneous network.

Indian National Gamma Array at IUAC

Indian National Gamma Array (INGA) is a 4π multi-detector gamma-ray spectrometer based on twenty four Compton-suppressed Clover Germanium detectors with a total photo peak efficiency ~ 5 %. INGA was designed to perform high resolution gamma-ray spectroscopy to study nuclear structure at high spins with stable ion beams at Inter University Accelerator Centre (IUAC). Description of the facility and performance of the array are presented in this paper. Since its commissioning, a number of nuclear spectroscopic investigations have been carried out using the array.

Follicular Changes In Relation To Menstrual Cycle In Female Of Fertile Age

Follicular changes studiedultrasonographically by Transabdominal as well as Transvaginal route during follicular monitoring in 81 patients of fertile age. These patients were referred for follicular monitoring in normal and stimulated cycles from infertility clinic. Patients’ compliance and acceptance was excellent for TVS technique as compared to TAS technique. For follicles > 20 mm in size, no significant difference was noted in detection rate between TAS and TVS. However, in smaller follicles especially below 10 mm the TVS offered definite improvement in the detection rates. Transabdominal methods underestimates the number of follicles, than does TVS. TV ultrasound measurement of follicular size has lower intra and inter-observer variability. Other studies also demonstrated that TVS scanning methods have a higher degree of patients compliance and acceptance of TVS has already been confirmed in our study. This highlights the need to make use of this mode of investigation for wider indications.

Real-time Detection of Botnet Behavior in Cloud Using Domain Generation Algorithm

In the last few years, the high acceptability of service computing delivered over the internet has exponentially created immense security challenges for the services providers. Cyber criminals are using advanced malware such as polymorphic botnets for participating in our everyday online activities and trying to access the desired information in terms of personal details, credit card numbers and banking credentials. Polymorphic botnet attack is one of the biggest attacks in the history of cybercrime and currently, millions of computers are infected by the botnet clients over the world. Botnet attack is an intelligent and highly coordinated distributed attack which consists of a large number of bots that generates big volumes of spamming e-mails and launching distributed denial of service (DDoS) attacks on the victim machines in a heterogeneous network environment. Therefore, it is necessary to detect the malicious bots and prevent their planned attacks in the cloud environment. A number of techniques have been developed for detecting the malicious bots in a network in the past literature. This paper recognize the ineffectiveness exhibited by the singnature based detection technique and networktraffic based detection such as NetFlow or traffic flow detection and Anomaly based detection. We proposed a real time malware detection methodology based on Domain Generation Algorithm. It increasesthe throughput in terms of early detection of malicious bots and high accuracy of identifying the suspicious behavior.

Analysis of Cherenkov Phase Matching in DAST for Terahertz Generation

Numerical simulation has been done to study the Cherenkov phase matching in DAST. Discrete regions of THz frequency in DAST have been identified to study the tuning characteristics.

1/f Noise properties of swift heavy ion irradiated epitaxial thin films of YBCO

Effect of 250 MeV107Ag ion irradiation induced columnar defects on the noise properties of the YBCO superconductor in the normal and superconducting state have been investigated. Magnitude of the spectral density of the noise is found to scale inversely with the frequency and exhibit a quadratic dependence on the bias current confirming that the noise arises due to the resistance fluctuations. The magnitude ofSv has been found to decrease with decrease in temperature and shows a noise peak in the transition region. The noise performance of these materials in the vicinity of the superconducting transition as well as in the normal state is found to improve by an order of magnitude after irradiation with 250 MeV107Ag ions. The decrease in the magnitude of 1/f noise peak is due the irradiation induced enhanced flux pinning of the material which suppresses the flux motion induced noise in the vicinity ofTc.