M YOUSAF - Academia.edu (original) (raw)

Papers by M YOUSAF

The Ulster medical journal, 2000

Acta Crystallographica Section C Crystal Structure Communications, 1999

Lecture Notes in Computer Science, 2009

IEEE recently standardized 802.21-2008 Media Independent Handover (MIH) standard. MIH is a key mi... more IEEE recently standardized 802.21-2008 Media Independent Handover (MIH) standard. MIH is a key milestone toward the evolution of integrated heterogeneous 4G wireless networks. MIH provides number of link layer events in a unified way that facilitate upper layer protocols in making handover decisions. One such event is Link Going Down (LGD) trigger. LGD is a predictive event that is generated when link conditions are expected to degrade in near future. Traditionally such link quality degradations and connectivity losses are predicted on the basis of a single parameter only i.e. received signal strength. However, in varying wireless conditions, simple predictions relying on single link layer parameter may generate false LGD triggers. This false triggering may initiate unnecessary handovers that rather than facilitating upper layer mobility management protocols, may cause overhead and may degrade the overall network performance. In this paper, we present an intelligent model for generating MIH LGD trigger reliably. In our implementation, we used 'Time Delay Neural Networks (TDNN)' approach using multiple link layer parameters for LGD predictions. We also analyzed the prediction accuracy and the feasibility of using such intelligent technique for mobile devices.

2012 International Conference on Computer & Information Science (ICCIS), 2012

With the advancement of technology and evolution of heterogeneous access networks, mobile devices... more With the advancement of technology and evolution of heterogeneous access networks, mobile devices are equipped with multiple network interfaces. Usually these mobile devices use single access network for communication, hence in case of node's mobility across heterogeneous networks this single network interface based communication results in higher handover delay and service disruption time. As today's mobile devices are multi-homed, and coverage area of different access networks usually overlap, hence mobile devices may have more than one active network interfaces. These active interfaces can be used simultaneously for communication. In this paper, we have discussed the effectiveness of multi-homing and parallel transmission during and after the vertical handover process. Results show that through the use of multi-homing and parallel transmission, handover delay and service disruption time can be reduced significantly and throughput can be increased.

Proceedings of the 8th International Conference on Frontiers of Information Technology, 2010

... sykahoot@yahoo.com Muhammad Yousaf Center for Advanced Studies in Engineering (CASE), Islamab... more ... sykahoot@yahoo.com Muhammad Yousaf Center for Advanced Studies in Engineering (CASE), Islamabad myousaf@ymail.com Amir Qayyum Center of Research in Networks and Telecom (CoReNeT), MA Jinnah University, Islamabad aqayyum@ieee.org ABSTRACT ...

2014 Conference on Information Assurance and Cyber Security (CIACS), 2014

A paradigm in which household substances around us with embedded computational competences and ca... more A paradigm in which household substances around us with embedded computational competences and capable of producing and distributing information is referred to as Internet of Things (IoT). IEEE 802.15.4 presents power efficient MAC layer for Internet of Things (IoT). For the preservation of privacy and security, Internet of Things (IoT) needs stern security mechanism so as to stop mischievous communication inside the IoT structure. For this purpose security weaknesses of the MAC protocol of IEEE 802.15.4 and their most important attacks have to be examined. Also security charter of IEEE 802.15.4 is to be analyzed in order to ascertain their limitations with regard to Internet of Things (IoT). Various ranges of attacks taking place in the Contention Free Period (CFP) in addition to Contention Access Period (CAP) of the super-frame structure needs to be explored and discussed. In view of the shortlisted weaknesses we would be arriving at the conclusion that the IEEE 802.15.4 security charter may be harmonized in accordance with the requirements of the Internet of Things. The missing functionalities may be incorporated in the upper layers of Internet of Things (IoT) Architecture.

2008 11th International Conference on Computer and Information Technology, 2008

Today's mobile devices are equipped with multiple network interfaces belonging to different acces... more Today's mobile devices are equipped with multiple network interfaces belonging to different access networks, these interfaces may be used in different requirements. A network connection should be established using the best possible interface. During communication, characteristics of a network may change or a new access network is reached by Mobile Node thus an already established connection should be moved from one interface to another or parallel transmission is done over two or more connections. In the last several years' variety of mobility management solutions have been proposed that operate at different layers of the communication protocol stack (e.g link layer, network layer, transport layer and application layer), but the network and transport layer mobility management solutions are more mature. In this paper we have discussed various end-to-end mobility management solutions for TCP. We have also identified a number of evaluation parameters and on the basis of these parameters different mobility management techniques are analyzed.

IFIP Advances in Information and Communication Technology, 2009

Vertical handover decision algorithm that is based on user preferences and coupled with Media Ind... more Vertical handover decision algorithm that is based on user preferences and coupled with Media Independent Handover (MIH) local triggers have not been explored much in the literature. We have developed a comprehensive cross-layer solution, called Vertical Handover Decision (VHOD) approach, which consists of three parts viz. mechanism for collecting and storing user preferences, Vertical Handover Decision (VHOD) algorithm and the MIH Function (MIHF). MIHF triggers the VHOD algorithm which operates on user preferences to issue handover commands to mobility management protocol. VHOD algorithm is an MIH User and therefore needs to subscribe events and configure thresholds for receiving triggers from MIHF. In this regard, we have performed experiments in WLAN to suggest thresholds for Link Going Down trigger. We have also critically evaluated the handover decision process, proposed Just-in-time interface activation technique, compared our proposed approach with prominent user centric approaches and analyzed our approach from different aspects.

2008 IEEE International Networking and Communications Conference, 2008

Page 1. On End-to-End Mobility Management in 4G Heterogeneous Wireless Networks Muhammad Yousaf A... more Page 1. On End-to-End Mobility Management in 4G Heterogeneous Wireless Networks Muhammad Yousaf Amir Qayyum Center for Advanced Studies in Engineering MA JinnahUniversity, (CASE), Islamabad Islamabad myousaf@case. edu.pk aqayyumgieee.org ...

Journal of the Optical Society of America B, 1991

A systematic experimental and theoretical study of first-order grating coupling to surface plasma... more A systematic experimental and theoretical study of first-order grating coupling to surface plasma waves existing at an air-Ag interface is presented. The experiment extends beyond previous work to grating depths comparable with the grating period. The grating profiles range from sinusoidal to rectangular. For TM-polarized incident radiation this grating depth range includes the entire spectrum of surface-plasma-wave-radiation coupling-from underdamped, to nearly 100%o coupling, to overdamped and the disappearance of the resonance from the zero-order reflectance measurements. Strong polarization and absorption effects are observed for the deepest gratings. A simple theoretical model, based on the Rayleigh hypothesis and retaining only resonant diffraction terms without a small-signal approximation being made, provides good agreement with the experimental results.

New Phytologist, 1981

SUMMARY Roots of the ferns examined in this investigation were constantly mycorrhizal. A mixture ... more SUMMARY Roots of the ferns examined in this investigation were constantly mycorrhizal. A mixture of several endophytes infecting a root system was a usual feature of them. Vesicular-arbuscular endophytes predominated over endophytes with a septate mycelium. Ectomycorrhizal fungi with a septate mycelium bearing clamp-connections ran longitudinally inside the cortex and occasionally these hyphae formed a mantle on the outside of the roots. A displacement of endotrophic mycorrhizas by ectomycorrhizal fungi occurred in Adiantum vemistum D. Don when growing under pine forest. Heavy arbuscular and vesicular infections occurred throughout the period of investigation. Several spore types were present in each rhizosphere.

Neural Networks, 2013

We investigate the generation and annihilation of persistent localized activity states, so-called... more We investigate the generation and annihilation of persistent localized activity states, so-called bumps, in response to transient spatiotemporal external input in a two-population neural-field model of the Wilson-Cowan type. Such persistent cortical states have been implicated as a biological substrate for short-term working memory, that is, the ability to store stimulus-related information for a few seconds and discard it once it is no longer relevant. In previous studies of the same model it has been established that the stability of bump states hinges on the relative inhibitory constant τ , i.e., the ratio of the time constants governing the dynamics of the inhibitory and excitatory populations: persistent bump states are typically only stable for values of τ smaller than a critical value τ cr. We find here that τ is also a key parameter determining whether a transient input can generate a persistent bump state (in the regime where τ < τ cr) or not. For small values of τ generation of the persistent states is found to depend only on the overall strength of the transient input, i.e., as long as the magnitude and duration of the excitatory transient input are larger and/or long enough, the persistent state will be activated. For higher values of τ we find that only specific combinations of amplitude and duration leads to persistent activation. For the corresponding annihilation process, no such delicate selectivity on the transient input is observed.

Journal of Network and Computer Applications, 2012

Mobility management for TCP connections has been discussed in literature since last several years... more Mobility management for TCP connections has been discussed in literature since last several years. Many mobility management solutions have been proposed including end-to-end solutions and infrastructure dependent solutions. These solutions operate at different layers of TCP/IP protocol stack. End-to-end mobility management solutions have the advantage of not requiring the deployment of additional entities in network infrastructure to handle mobility management as compared to the infrastructure dependant solutions. Performance analysis of these end-to-end mobility management protocols seems missing in literature. In this paper, we analyze the performance of different end-to-end mobility management protocols using mathematical modeling. Evaluation has been carried out for evaluating the handover delay, throughput degradation time and protocol overhead. Some security and implementation issues pertaining to these protocols have also been discussed. Results show that protocols that allow simultaneous communication through multiple network interfaces provide throughput stability during vertical handovers, thus facilitating smooth handovers.

Journal of Animal Physiology and Animal Nutrition, 2009

A 6-week feeding trial was conducted to determine the effects of varying dietary electrolyte bala... more A 6-week feeding trial was conducted to determine the effects of varying dietary electrolyte balance (DEB) on growth performance and physiological responses in broiler chicks reared during hot summer months (26.1-37.5°C). The average minimum and maximum room temperatures recorded from 14 to 42 days of age were 26.1 and 37.5°C, respectively, with relative humidity ranging from 51% to 55%. Five DEB treatments supplying 0, 50, 150, 250 and 350 (Na + +K +-Cl)) mEq/kg of diet were prepared by adding NaHCO 3 and/or NH 4 Cl to basal diet that contained 185 mEq/kg from 1 to 28 days and 172 mEq/kg from 29 to 42 days. These DEB diets were randomly offered to six experimental units of 20 chicks each. Improved 42-day body weight gain (BWG), feed:gain (F:G) and reduced mortality was noted with DEB 50, 150 and 250 mEq/kg compared to DEB 0 and 350 mEq/kg. A quadratic effect of increasing DEB level was observed on BWG and F:G, whereas the effect was linear for feed intake, water intake and litter moisture. The DEB 50, 150 and 250 maintained better blood pH, pCO 2 and HCO 3 concentrations during acute heat stress periods than that of 0 and 350. The blood heterophil and lymphocyte percent as well as heterophil:lymphocyte were remained unaffected. The lowest DEB (0 mEq/kg) diet reduced the feed intake and promoted metabolic acidosis. At 350 mEq/kg DEB, water intake and metabolic alkalosis were promoted probably due to high levels of dietary NaHCO 3. The study concluded that overall better performance was recorded with DEB 50, 150 and 250 mEq/kg. These results indicated that single optimal DEB value could not be recommended to combat heat stress in broilers.

Irish Journal of Medical Science, 2005

Gastrointestinal stromal tumour (GIST) has many modes of presentation. This is the first reported... more Gastrointestinal stromal tumour (GIST) has many modes of presentation. This is the first reported GIST presenting as an acute abdomen. A man presented with signs and symptoms suggestive of acute appendicitis. Examination under anaesthesia revealed a mass. At laparotomy a strangulated mass was found originating from the greater curve of the stomach. Subsequent histopathology confirmed this to be a gastrointestinal stromal tumour, probably of a benign nature. Post-operative investigations did not show any metastatic spread. GISTs arise from the gastrointestinal tract, omentum, and mesentery. Presentation is generally non-specific and it is rare for them to present acutely. Management should include staging to exclude any metastatic spread.

HETEROCYCLES, 1998

Phytochemical studies on the whole plant of Withania coagulans have resulted in the isolation of ... more Phytochemical studies on the whole plant of Withania coagulans have resulted in the isolation of five new withanolides, namely coagulins H, I, J, K and L (1 5 Their structures have been established as (17S,20S,22R)-5a,6P,14a, 15a,l7,20-hexahydroxy-1-oxowitha-2,24-dienolide (I), (14R,17S,

Diseases of the Colon & Rectum, 2004

Perineal sinus is a troublesome complication after proctectomy for inflammatory bowel disease or ... more Perineal sinus is a troublesome complication after proctectomy for inflammatory bowel disease or rectal cancer. The results from treatment with simple dressings with or without surgical debridement are suboptimal. Definitive management may require complex operations with muscular or musculocutaneous flaps. Vacuum-assisted dressings have been used successfully for management of chronic wounds and soft tissue defects. This technique was successfully used in the management of a perineal sinus, which occurred after proctectomy for rectal cancer developing on a background of inflammatory bowel disease and preoperative radiotherapy.

INTERDISCIPLINARY …, 2011

The purpose of this study is to determine the relationship between employee empowerment and job s... more The purpose of this study is to determine the relationship between employee empowerment and job satisfaction in Pakistani service industry. This study also examines the difference between job satisfaction level of male and female employees. The questionnaire consisting twenty four statements was used for collection of data and was distributed among 200 employees of service industries in Pakistan. SPSS was used for analysis. Results indicate that employee empowerment has positive and significant impact on job satisfaction. The results also confirm a significant difference between male and female employees job satisfaction level. Evidence depicts that male employees are more satisfied from their jobs.

ISSN: 0253-8318 (PRINT), 2074-7764 (ONLINE) Accessible at: www.pvj.com.pk ... Clinicopathological... more ISSN: 0253-8318 (PRINT), 2074-7764 (ONLINE) Accessible at: www.pvj.com.pk ... Clinicopathological Studies on Gentamicin Toxicity in White Leghorn Commercial Layers ... Najam Ul Islam, M. Zargham Khan1, M. Kashif Saleemi*1, Ahrar Khan1, Sheraz Ahmed Bhatti1, Muhammad Yousaf2 ...

Proceedings of the 7th International Conference on Advances in Mobile Computing and Multimedia, 2009

Whenever a mobile node moves across different networks, service disruption occurs thus making mob... more Whenever a mobile node moves across different networks, service disruption occurs thus making mobility management a key issue. In order to ensure the continuity of TCP session between communicating nodes, a number of protocols have been proposed so far. These protocols may be classified into two main categories: end-to-end and network-centric. As end-to-end mobility management protocols do not require additional entities in the network and no additional deployment cost is involved, that makes deployment of these protocols network operator independent. Due to these reasons end-to-end mobility management protocols are gaining popularity. However, performance evaluation of these end-to-end protocols on the basis of service disruption time has not been discussed so far. This paper analyzes these protocols on the basis of service disruption time using mathematical modeling techniques of performance evaluation. Results show that service disruption time of protocols that allow simultaneous communication through multiple interfaces is always smaller than the protocols that do not allow simultaneous communication.