Effects of Climate on Rice Yield in the Punjab Province, Pakistan

abbas sohail,HUSSAIN SABIR,이승호 대한지리학회 2020 대한지리학회지 Vol.55 No.3

This study presents the effects of climate on rice yield in the Punjab province of Pakistan. A correlation method was employed to examine the relationship between climate elements and rice yield from 1989 to 2018. The effects of climate on rice crop is estimated using the stepwise regression on the significant correlation elements. The analysis founds the positive relationship of rainfall and rice yield at re-plantation stage in the Central and Southern regions. The maximum temperature of re-plantation stage showed a negative relationship with rice yield in the Southern and Western regions. The minimum temperature of tillering, stem elongation and flowering stages had a negative relationship with rice yield in the Central region. The maximum temperature of flowering stage was indicated a negative relationship to rice yield in the Southern and Western regions. The stepwise regression analysis confirms a significant positive effect of rainfall to rice yield in the Southern region and a significant negative effect of maximum temperature on rice yield in the Southern and Western regions at re-plantation stage. The minimum and maximum temperatures of flowering stage negatively affects rice yield in the Central and Western regions respectively.

Metal-Oxide Heterojunction for Semi-Transparent and High-Speed Ultra-Violet Photodetector

Sohail Abbas,Mohit Kumar,김준동 한국진공학회 2018 한국진공학회 학술발표회초록집 Vol.2018 No.2

A Review of Studies on Changes in Precipitation Features over Pakistan

Sohail Abbas,Mian Sabir Hussain,임수정,신보미,이승호 건국대학교 기후연구소 2021 기후연구 Vol.16 No.4

This study provides a comprehensive review on the trend of precipitation research work over Pakistan. An integrated literature review is developed by combining the various content analysis to explore a systematic trend of precipitation studies in Pakistan. The review was extended up to Indian research work of precipitation to identify the role of affecting elements to regional precipitation of Pakistan. The review is focused on two national journals and eighteen international journals about geography, climate, and meteorology during 1981-2020. The proportion of reviewed articles was 84 and 16 percent for international and local journals respectively. Various features of precipitation research in international journals have rapidly increased during 2009-2020, which was four-time greater than research published during 1981-2008. Regarding various features of precipitation, the ratio of reviewed studies was 54%, 21%, 16%, and 6% for atmospheric circulation, annual and seasonal precipitation, extreme precipitation, and regional distribution of precipitation respectively. While the studies of climate change and its impact on human was not big in numbers in Pakistan. The review of precipitation studies revealed that the aspect of precipitation intensity was more focused on by climate scientists during the last three decades. The occurrence of precipitation intensity indicates an increasing trend of extreme events particularly in the central plain, northwestern mountain, and Kashmir region during the monsoon season. There is no specific research was studied to assess the trend shift changes of precipitation in the recent decades.

Thwarting Sybil Attackers in Reputation-based Scheme in Mobile Ad hoc Networks

( Sohail Abbas ),( Madjid Merabti ),( Kashif Kifayat ),( Thar Baker ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.12

Routing in mobile ad hoc networks is performed in a distributed fashion where each node acts as host and router, such that it forwards incoming packets for others without relying on a dedicated router. Nodes are mostly resource constraint and the users are usually inclined to conserve their resources and exhibit selfish behaviour by not contributing in the routing process. The trust and reputation models have been proposed to motivate selfish nodes for cooperation in the packet forwarding process. Nodes having bad trust or reputation are detected and secluded from the network, eventually. However, due to the lack of proper identity management and use of non-persistent identities in ad hoc networks, malicious nodes can pose various threats to these methods. For example, a malicious node can discard the bad reputed identity and enter into the system with another identity afresh, called whitewashing. Similarly, a malicious node may create more than one identity, called Sybil attack, for self-promotion, defame other nodes, and broadcast fake recommendations in the network. These identity-based attacks disrupt the overall detection of the reputation systems. In this paper, we propose a reputation-based scheme that detects selfish nodes and deters identity attacks. We address the issue in such a way that, for normal selfish nodes, it will become no longer advantageous to carry out a whitewash. Sybil attackers are also discouraged (i.e., on a single battery, they may create fewer identities). We design and analyse our rationale via game theory and evaluate our proposed reputation system using NS-2 simulator. The results obtained from the simulation demonstrate that our proposed technique considerably diminishes the throughput and utility of selfish nodes with a single identity and selfish nodes with multiple identities when compared to the benchmark scheme.

Urban Growth and Its Effect on Temperature Trends of Lahore City, Pakistan

Sohail Abbas,Mian Sabir Hussain,Sujeong Im,Seungho Lee,Safdar Ali Shirazi 건국대학교 기후연구소 2018 기후연구 Vol.13 No.3

The current study deals with the effect of urban growth and urbanization on temperature trends over Lahore city of Pakistan. This research was conducted using mean monthly temperature data for the period of 1950-2017. The urban population growth, urban expansion, the increase of vehicles and factories as well as the expansion of built up area have influenced on the change of temperature in Lahore city. The annual trends of temperatures have been analyzed, and their statistical significances are calculated by the linear regression method. It has been deduced that there is a close relation between temperature change and urban growth. The findings are as follows; the mean minimum temperature rises greater than the maximum temperature at urban station and rural station. However, the maximum temperature is not rising positively and thus significantly at both stations. The findings show the fact that mean minimum temperature increasing more quickly after the 1995 due to the increase of urban development in Lahore city in which the built up area has increased from 66 km² to 740 km² since 1950. A massive increase in the numbers of vehicles have also influenced on the change of temperature in the city. However, the mean maximum temperature at rural station of Lahore has significant effect during 1973-1997.

Changes of Extreme Precipitation Trends in Pakistan during 1961-2020

Sohail Abbas,이승호 건국대학교 기후연구소 2024 기후연구 Vol.19 No.1

This study analyzed changes in extreme precipitation trends over Pakistan for the period of 1961-2020. The changes in extreme precipitation trends were compared between two normal climate periods (1961-1990 and 1991-2020) over different precipitation regions of Pakistan. The Mann-Kendall test was applied to validate the trends of extreme precipitation. The changing rate of extreme precipitation trends was measured by Sen’s slope estimator. The results show that the number of heavy precipitation days increased in the Baluchistan plateau, Central plains, and Core monsoon regions for the period of 1961-1990 while decreased in the Southern desert regions in the period 1991-2020. The very heavy precipitation days increased in the Central plain, Muree Hills, Potwar, and Upper Indus pain regions during the period of 1991-2020. The decreasing trends of annual precipitation on wet days were analyzed in the Upper Indus Plain, Potwar, and Central Plains regions of the country. An increase in the number of five consecutive days was observed in the Potwar region, while it decreased in the Southern desert regions of the country during the period of 1991-2020. The analysis showed a significant increase in the intensity of extreme precipitation over the Northwestern mountainous, Muree Hills, and Central Plains regions of the country over the last three decades. Overall, the intensity of all extreme precipitation indices (R10, R20, PRCPTOT, and RX5) increased with greater tendency over the Northwestern mountain and Central plain regions while decreased in the Northwestern Baluchistan plateau and Southwestern regions of Quetta during the period of 1991-2020 compared to 1961-1990.

Survivability Analysis of MANET Routing Protocols under DOS Attacks

( Sohail Abbas ),( Muhammad Haqdad ),( Muhammad Zahid Khan ),( Haseeb Ur Rehman ),( Ajab Khan ),( Atta Ur Rehman Khan ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.9

The network capability to accomplish its functions in a timely fashion under failures and attacks is known as survivability. Ad hoc routing protocols have been studied and extended to various domains, such as Intelligent Transport Systems (ITSs), Unmanned Aerial Vehicles (UAVs), underwater acoustic networks, and Internet of Things (IoT) focusing on different aspects, such as security, QoS, energy. The existing solutions proposed in this domain incur substantial overhead and eventually become burden on the network, especially when there are fewer attacks or no attack at all. There is a need that the effectiveness of these routing protocols be analyzed in the presence of Denial of Service (DoS) attacks without any intrusion detection or prevention system. This will enable us to establish and identify the inherently stable routing protocols that are capable to survive longer in the presence of these attacks. This work presents a DoS attack case study to perform theoretical analysis of survivability on node and network level in the presence of DoS attacks. We evaluate the performance of reactive and proactive routing protocols and analyse their survivability. For experimentation, we use NS-2 simulator without detection or prevention capabilities. Results show that proactive protocols perform better in terms of throughput, overhead and packet drop.

All metal oxide-based transparent and flexible photodetector

Abbas, Sohail,Kumar, Mohit,Kim, Joondong Elsevier 2018 Materials science in semiconductor processing Vol.88 No.-

<P><B>Abstract</B></P> <P>We demonstrate the fabrication and characterization of flexible and transparent photodetector based on conformally grown Ag<SUB>x</SUB>O/TiO<SUB>2</SUB>/ITO layers on polyethylene terephthalate substrate. Initially, the thickness of Ag<SUB>x</SUB>O and ITO layers were optimized via deposition time to match layers crystallinity with fixed intermediate TiO<SUB>2</SUB> layer, for better optical and electrical properties. The highly transparent (> 70%) and flexible device presents the high-preforming responses over the broadband light. Under UV illumination, it showed a high responsivity (323 mA/W) and detectivity (4.2 × 10<SUP>8</SUP> Jones). Similarly, a noise equivalent power of 2.3 × 10<SUP>−9</SUP> W/Hz<SUP>1/2</SUP> is obtained, which confirmed its capability to detect light at nanowatt level. Moreover, mechanical flexibility test was performed for the flexible and transparent Ag<SUB>x</SUB>O/TiO<SUB>2</SUB>/ITO device. It was found that the device is robust to have good optoelectronic performances even after 500 no. of bending cycles. Thus, the utilization of earth abundant metal-oxides can facilitate the flexibility, durability and transparency of next generation optoelectronic devices.</P>

Silver-Nanowire-Embedded Transparent Metal-Oxide Heterojunction Schottky Photodetector

Abbas, Sohail,Kumar, Mohit,Kim, Hong-Sik,Kim, Joondong,Lee, Jung-Ho American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.17

<P>We report a self-biased and transparent Cu<SUB>4</SUB>O<SUB>3</SUB>/TiO<SUB>2</SUB> heterojunction for ultraviolet photodetection. The dynamic photoresponse improved 8.5 × 10<SUP>4</SUP>% by adding silver nanowires (AgNWs) Schottky contact and maintaining 39% transparency. The current density-voltage characteristics revealed a strong interfacial electric field, responsible for zero-bias operation. In addition, the dynamic photoresponse measurement endorsed the effective holes collection by embedded-AgNWs network, leading to fast rise and fall time of 0.439 and 0.423 ms, respectively. Similarly, a drastic improvement in responsivity and detectivity of 187.5 mAW<SUP>-1</SUP> and of 5.13 × 10<SUP>9</SUP> Jones, is observed, respectively. The AgNWs employed as contact electrode can ensure high-performance for transparent and flexible optoelectronic applications.</P> [FIG OMISSION]</BR>

Evaluating Changes in Seasonal Precipitation Trends over Pakistan

Sohail Abbas,이승호 건국대학교 기후연구소 2022 기후연구 Vol.17 No.3

This study presents changes in seasonal precipitation trends over Pakistan. The Mann-Kendall technique was applied to estimate the trends of seasonal precipitation for the periods of 1961-1990 and 1991-2020. The study reveals a significant decrease in pre-monsoon precipitation over the northwest and southwest regions of the country from 1991-2020. The summer monsoon precipitation has a significant decreasing trend in the east-west and an increase in the southwest areas of Pakistan from 1961-1990. While the east-west, central, and southeast areas indicated a significant increasing trend between 1991-2020. The results revealed that post-monsoon precipitation significantly decreased in east-western regions in the second half as compared to the first half of the investigated period. The statistical analysis also revealed significant increasing trends of precipitation for northeast areas of Pakistan during the winter season for the period of 1961-1990 as compared to 1991-2020. The winter precipitation also significantly decreased in the northern (humid) and southern (coastal) regions and increased in the eastern and western areas in the second half period. Conclusively, significant decreasing trends were analyzed in the southwest and central regions from 1991-2020 and increasing trends in the eastern and northern core monsoon regions of Pakistan in all seasons except post-monsoon during 1961-1990.