From a security perspective, a jamming attack is easy to launch and relatively hard to detect. Jamming attacks are generally directed towards seizing the medium completely by transmitting fake packets violating the medium access protocol, either constantly or periodically. This work analyzes the effects of different types of jammers using Conservation of Flow (CoF), which has been useful for detecting other attacks in wired networks. Additionally, simulation results are presented in justification of proposed methodology. With the miniaturization of wireless devices, the popularity and usage has increased in recent past, especially due to portability. Since the design of such devices does not primarily emphasize heavy computation and secure communication, these are treated as add-ons. In setting up an ad hoc network rather than choosing all or more than the channels offered by 802.11 standard, only a single channel is generally utilized to minimize delay and synchronization issues. However, by using additional available multiple channels, significant gain in terms of overall system performance can be achieved. This, and other limitations like a shared medium which is open to all, attracts intruders in wireless networks. Mainly, the use of a lone channel can become single point of failure in case of an attack, especially a jamming attack. In contrast to other security attacks, no special hardware and computation is required in launching jamming attacks. Additionally, even if the attacker does not get hold of the communication, he can emit radio signals periodically to jam legitimate conversation. Thus, legitimate nodes escape physically or logically to avoid a jammer at the cost of additional overhead involving coordination amongst nodes to resume communication. The overhead involved in either of the methods is considered worthy in terms of regaining the performance of the network. In this thesis, a couple of MAC layer-based algorithms are proposed to mitigate the effects of jamming attacks efficiently; the first is a reactive mechanism and the second is a proactive proposal. The work starts with an investigation of different jamming types and their effects on wireless communication. For this purpose, a simulation model was developed and the resulting data set was verified using AI algorithms, which predicted 98% accuracy. Next, a reactive technique namely packet-feed is proposed to keep the jammer busy on the jammed channel. Once the nodes detect the existence of the jammer and hop to another channel, they alternatively visit the earlier channel to feed the jammer with valid packets. This way, the nodes pretend to the jammer that the earlier channel is still in use. Finally, a proactive channel hopping protocol is proposed where each node has a separate and dynamically selected control channel. Additionally, rather than each of them feeding the other its channel hopping sequence, both parties coordinate to come up with a new channel where data transfer can take place. Thus, provision of redundant channels is provided to each node. Following on from this, the proposed idea is analyzed with the existence of a jammer.
أمطري، لا ترحمي طیفي في عمقِ الظلام أمطري، صبّي علیّ السیل، یا روح الغمام لا تُبالي([2]) أن تعیدیني علی الأرض حطام وأحیلیني([3]) ، إذا شئت، جلیداً أو رُخام
أترکي ریح المساء الممطر الداجي([4]) تجنّ ودعي الأطیار، تحت المطر القاسي، تئنّ أغرقي الأشجار بالماءِ ولا یحزنکِ غصن زمجري([5])، دويّ([6])، فلن أشکو، لن یأتیک لحن
أمطري فوقي، کماشئت، علی وجھي الحزین لا تبالي جسدي الراعش، في کفّ الدجون([7]) أمطري، سیلي علی وجھي، أو غشيّ عیوني بلّلي ما شئت کفيّ وشعري وجبیني
أغرقي، في ظلمۃ اللیل، القبور البالیہ([8]) وألطمي، ما شئتِ أبواب القُصور العالیہ أمطري، في الجبل الناءي([9])، وفوق الھاویۃ([10]) أطفءي النیران، لا تُبقي لحيّ باقیہ
آہ ما أرھبکِ الآن، وقد ساد السکون غیر صوتِ الرّیح، في الأعماق([11]) تدوي في جنون لم تزل تھمي([12])، من الأمطار، في الأرض، عیون لم یَزٖل، قلبي حزیناً، تحت أمواج الدُجون
أیّھا الأمطارُ، قد ناداکِ قلبي البشريُّ ذلک المفرق في الأشواق، ذاک الشاعريّ إغسلیہ، أم تری الحزنُ حماہ([13]) الأبديّ أبداً ، مثلک یا أمطارُ، دفاقٌ نقيُّ
أبداً یسمعُ، تحت اللیل، وقعَ القطرات ساھماً یحلم بالماضي وألغاز الممات یسأل الأمطار: ما أنتِ؟ وما سرّ الحیاۃ؟ وأنا، فیم وجودي؟ فیم دمعي وشکاتي([14])؟
The present study is aimed to examine the relation of Holy Qur’ān recitation and psychological wellbeing among the Muslim Youth. People find no time for offering prayers and reciting Holy Qur’ān because they are very busy in their daily routines and if they do so, they do it for short period of time when they are in some trouble. The objectives include firstly the exploration of the relationship of Holy Qur’ān recitation and psychological wellbeing. Second objective of the study is to explore the correlation of the Holy Qur’ān recitation with depression, anxiety and stress among young Muslims. Study sample comprises of 100 young Muslims (43 males and 57 females) falling between 17 and 25 years from Rawalpindi and Islamabad. Instruments used for data collection include psychological wellbeing scale by Kamman and Flett (1983) and DASS (depression anxiety stress scale) by Lovibond and Lovibond (1995) and a demographic sheet. Results of the study showed that significant positive relationship exists between Holy Qur’ān recitation and psychological wellbeing among young Muslims and Holy Qur’ān recitation negatively relates with depression, anxiety and stress. The present study findings support that those young Muslims who had more rate of Holy Qur’ān recitation were psychologically more stable as compared to non-frequent reciters. In the light of findings of current study, it can be declared as a quintessence that Holy Qur’ān Recitation can serve as an influential element in ensuring the positive mental health of youth. Educators and Policy makers can play a crucial role in promotion of Holy Qur’ān familiarity which will make certain the psychological and mental health of youth and of the society at large.
Two sets of field experiments were conducted each during autumn 2006 and 2007 to investigate the influence of varying ridge spacing and planting density on growth characteristics, agronomic and yield traits, quality of grain, and nutrient up-take patterns of diverse maize (Zea mays L.) hybrids. Another objective was to optimize planting density for good harvests of maize grown on narrow (45 cm and 60 cm) as against conventional (75 cm apart) ridges In Experiment-I three diverse maize hybrids, DK-919 (early maturity), DK-5219 (medium maturity) and Pioneer-30Y 87 (late maturity) were planted at ridges spacing of 45, 60 and 75 cm each. In Experiment-II, maize hybrid DK- 919 was planted at three inter ridge spacing of 45, 60 and 75 cm as main plot and 15, 22.5 and 30 cm intra-ridge spacing imposed as sub plots. Both the experiments were quadruplicated and each sub plot consisted of 6 rows of 7.0 m length. Results revealed that DK-919 recorded total dry matter (17409 kg ha -1 ) that was 19% and 8% higher than DK-5219 and Pioneer-30Y87, respectively. Maize planted at 45 cm ridge spacing produced 14% and 34 % higher total dry matter than that 60 and 75 cm spaced ridge sown crop. Plant spacing of 15 cm produced 42 and 22% higher dry matter than that recorded for 30 cm and 22.5 cm plant spacing. Early maturing hybrid, DK-919, realized 17 and 6%, higher grain yield than mid and late maturity maize hybrids, respectively. Early and late maize hybrid performed best at 45 cm ridge spacing while mid season hybrid did best at 60 cm ridge spacing. Narrowing the ridge spacing from 75 to 60 cm increased grain yield by 11-18 % while further decrease in ridge spacing from 60 cm to 45 cm resulted in 6-8% increase in grain yield. Decreasing ridge spacing from 75 cm to 45 cm enhanced grain yield by 17-24 % in both the experiments. Reducing intra ridge spacing from 30 cm to 15 cm enhanced grain yield by 25%. Highest grain yield (7606-7027 kg ha -1 ) was obtained at plant spacing of 60 cm x 15 cm (11 plants m -2 ) and was followed by 10 plants m -2 ). DK-919 exhibited higher HI as compared with DK-5219 and Pioneer-30Y87. Harvest indices improved initially with narrowing the plant and ridge spacing but declined when planting densities were increased further. Yield components as number of grains per ear and 1000 grain weight were significantly varied among maize hybrids and with changing ridge and plant spacing during both the growing seasons. Grain yield was linearly related to number of grains per unit area during both the season and regression accounted for about 90-98% of variation in grain yield. Tall and late season hybridPioneer 30Y87 exhibited higher LAI values. Differences in LAI between maize hybrids and ridge spacing remained significant throughout growth period and reached the maximum value of 5.33, 5.83 and 6.19 at 45, 60 and 75 cm ridge spacing, respectively. Highest LAI values corresponded to the anthesis time of the crop. Seasonal accumulation of TDM was higher until 60 DAS. Then there was a steady decrease in accumulation of TDM in all the hybrids and at all ridge spacing. Highest seasonal accumulation of TDM was recorded at planting density of 45 cm x 15 cm. Short season hybrid DK-919 had higher NAR than mid or late season hybrid. Narrow rows (45 cm) had higher NAR values than wider ridge spacing. Early maturing maize hybrid DK-919 had higher CGR than that DK-5219 (mid) and Pioneer-30Y87 (late). TDM production was positively and linearly related with total seasonal LAD in both the seasons. Total seasonal LAD explained 98% of variation in TDM production. In general, decreasing ridge and plant spacing enhanced CGR. Pioneer-30Y87 had highest grain oil content when planted at 75 cm ridge spacing. DK-919 had highest grain protein content when planted at 75 cm spacd ridge. DK-5219 and DK-919 planted each at 45 and 60 cm ridge spacing had highest and similar grain starch % than Pioneer-30Y87. Grain oil contents were reduced at narrow ridge and plant spacing (higher planting densities). Highest grain oil content was recorded at wider ridge (75 cm) and plant spacing (30 cm). Grain protein and starch contents decreased with narrow ridge (45 cm) and plant (15 cm) spacing. Results on nutrient uptake patterns revealed that DK-919 recorded higher N, P and K uptake than DK-5219 and Pioneer- 30Y87 at all growth stages. Narrowing the ridge and plant spacing resulted in improved nutrient uptake that was highest at 45 cm ridge and 15 cm plant spacing. On the basis of two years result, it is concluded that maize hybrid DK-919 (early maturing) should preferably be grown at narrow ridges (45 cm) for obtaining high yields. Mid season hybrids like DK-5219 need to be planted at 60 cm ridge spacing while late season hybrid as Pioneer-30Y87 reflected an increasing trend in yield with narrowing ridge spacing in these studies. For higher yield goals, autumn planted hybrid maize can be sown at plant spacing of 60 cm x 15 cm (11 plants m -2 )