RLECN—A learning based dynamic threshold control of ECN

Shahzad,정은성,김형석 한국통신학회 2023 ICT Express Vol.9 No.6

Explicit congestion notification (ECN) enables the network routers to mark packets instead of dropping them. When the queue size reaches a certain threshold, the queued packets are marked to indicate predicted congestion. However, an optimal value of the ECN threshold is not defined. A pre-decided value is chosen either by estimation or by hit and trial and therefore, it does not generalize well under a wide range of network scenarios. We propose a reinforcement learning (RL)-based ECN mechanism that utilizes software-defined networks (SDN) to address this problem. Our solution enables the routers to keep a dynamic ECN threshold according to the current network conditions. SDN provides the network visibility and reach to train the RL model and to dynamically adjust the ECN threshold. We show through experimental results that our proposed model outperforms the current state of the art.

Biomass-Derived Thermally Annealed Interconnected Sulfur-Doped Graphene as a Shield against Electromagnetic Interference

Shahzad, Faisal,Kumar, Pradip,Kim, Yoon-Hyun,Hong, Soon Man,Koo, Chong Min American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.14

<P>Electrically conductive thin carbon materials have attracted remarkable interest as a shielding material to mitigate the electromagnetic interference (EMI) produced by many telecommunication devices. Herein, we developed a sulfur-doped reduced graphene oxide (SrGO) with high electrical conductivity through using a novel biomass, mushroom-based sulfur compound (lenthionine) via a twostep thermal treatment. The resultant SrGO product exhibited excellent electrical conductivity of 311 S cm(-1), which is 52% larger than 205 S cm(-1) for undoped rGO. SrGO also exhibited an excellent EMI shielding effectiveness of 38.6 dB, which is 61% larger than 24.4 dB measured for undoped rGO. Analytical examinations indicate that a sulfur content of 1.95 atom % acts as n-type dopant, increasing electrical conductivity and, therefore, EMI shielding of doped graphene.</P>

Thickness dependent magnetic and ferroelectric properties of LaNiO3 buffered BiFeO3 thin films

Shahzad Hussain,S.K. Hasanain,G. Hassnain Jaffari,S. Ismat Shah 한국물리학회 2015 Current Applied Physics Vol.15 No.3

BiFeO3 (BFO) thin films with thickness increasing from 40 to 480 nm were successfully grown on LaNiO3 (LNO) buffered Pt/Ti/SiO2/Si(100) substrate and the effects of thickness evolution on magnetic and ferroelectric properties are investigated. The LNO buffer layer promotes the growth and crystallization of BFO thin films. Highly (100) orientation is induced for all BFO films regardless of the film thickness together with the dense microstructure. All BFO films exhibited weak ferromagnetic response at room temperature and saturation magnetization is found to decrease with increase in film thickness. Well saturated ferroelectric hysteresis loops were obtained for thicker films; however, the leakage current dominated the ferroelectric properties in thinner films. The leakage current density decreased by three orders of magnitude for 335 nm film compared to 40 nm film, giving rise to enhanced ferroelectric properties for thicker films. The mechanisms for the evolution of ferromagnetic and ferroelectric characteristics are discussed.

Indoleacetic acid production and plant growth promoting potential of bacterial endophytes isolated from rice (Oryza sativa L.) seeds

Shahzad, Raheem,Waqas, Muhammad,Khan, Abdul Latif,Al-Hosni, Khadija,Kang, Sang-Mo,Seo, Chang-Woo,Lee, In-Jung AKADEMIAI KIADO BUDABPEST 2017 Biologia futura Vol.68 No.2

<P>Bacterial endophytes from the phyllosphere and rhizosphere have been used to produce bioactive metabolites and to promote plant growth. However, little is known about the endophytes residing in seeds. This study aimed to isolate and identify seed-borne bacterial endophytes from rice and elucidate their potential for phytohormone production and growth enhancement. The isolated endophytes included Micrococcus yunnanensis RWL-2, Micrococcus luteus RWL-3, Enterobacter soli RWL-4, Leclercia adecarboxylata RWL-5, Pantoea dispersa RWL-6, and Staphylococcus epidermidis RWL-7, which were identified using 16S rRNA sequencing and phylogenetic analysis. These strains were analyzed for indoleacetic acid (IAA) production by using GC-MS and IAA was found in the range of 11.50 +/- 0.77 mu g ml(-1) to 38.80 +/- 1.35 mu g ml(-1). We also assessed the strains for plant growth promoting potential because these isolates were able to produce IAA in pure culture. Most of the growth attributes of rice plants (shoot and root length, fresh and dry biomass, and chlorophyll content) were significantly increased by bacterial endophytes compared to the controls. These results show that IAA producing bacterial endophytes can improve host-plant growth traits and can be used as bio-fertilizers.</P>

A Study on IPTV Standardization

Shahzad, Aamir,Ali, Mumtaz,Shin, Seo-Yong,Kim, Han-Su Korean Society for Internet Information 2007 인터넷정보학회지 Vol.8 No.3

The IPTV Standardization work being done by the ITU-T in collaboration with other SDOs and telecommunication companies. Currently IPTV services are provided with no global standards and interoperability. ITU-T leads the process of IPTV standardization. We used the ITU-Ts working documents which were publically available to investigate the direction of IPTV standardization process. Many things including architecture, services, service requirements, codec and error correction mechanisms etc already defined through recommendations. But still there is effort going on to standardize the complete IPTV system.

Highly sensitive electrochemical sensor based on environmentally friendly biomass-derived sulfur-doped graphene for cancer biomarker detection

Shahzad, F.,Zaidi, S.A.,Koo, C.M. Elsevier Sequoia 2017 Sensors and actuators. B, Chemical Vol.241 No.-

<P>Herein, we demonstrate a sulfur-doped reduced graphene oxide (SrGO) product fabricated using an ecofriendly biomass precursor 'lenthionine' through a high temperature doping process. The product is used for making a highly sensitive electrochemical sensor for detection of 8-hydroxy-2'-deoxyguanosine (8-OHdG) molecule, which is an important biomarker for oxidative stress, cardiovascular diseases, and cancers. The sulfur-doping amount was regulated and a maximum sulfur content of 2.28 atom% was achieved through controlling the precursor amount. Homogenous presence of large number of sulfur atoms in SrGO in the form of thiophenic (-C-S-C-) bond produced robust sensitivity (similar to 1 nM), very wide detection window (20-0.002 mu M), good selectivity, high stability and reproducibility, and excellent recoveries for the detection of 8-OHdG biomarker in optimized experimental conditions. The excellent electrochemical sensitivity of SrGO sensor is attributed to the strong electron-donating ability of sulfur that facilitates the electron transfer to the biomolecules in the electrochemical reactions. Thus, the proposed method endorses an excellent platform for the electrochemical detection of 8-OHdG with great ease and reliability. (C) 2016 Elsevier B.V. All rights reserved.</P>

Impact of Social and Institutional Quality Capital on Total Factor Productivity and Economic Growth

Shahzad Saeed,유태환 경성대학교 산업개발연구소 2018 산업혁신연구 Vol.34 No.3

This study examines whether economic growth is affected by social and institutional quality capital directly or indirectly via total factor productivity (TFP). Based on the fifth-wave data of the World Values Survey conducted during 1995–2014 (2005–2009 for short-run analysis), we adopt a cross-sectional and pooled time series regression framework to investigate the role of social and institutional quality capital on economic growth and TFP changes for 12 high-income and 15 low- and middle-income countries (24 high-income and 25 low- and middle-income countries for the short-run), respectively. The research extrapolates that there are considerable differences in the strength of impact for social and institutional quality capital in the countries with different income levels over different time horizons. Specifically, social capital explicates a positive effect on economic growth only for high-income countries in the long-run. While having both direct and indirect effects, the institutional quality capital affects economic growth indirectly via TFP with a higher magnitude, except for low- and middle-income countries in the long-run, compared to the short-run with regard to other income groups.

Heterostructural TiO₂/Ti₃C₂T_x (MXene) for photocatalytic degradation of antiepileptic drug carbamazepine

Shahzad, Asif,Rasool, Kashif,Nawaz, Mohsin,Miran, Waheed,Jang, Jiseon,Moztahida, Mokrema,Mahmoud, Khaled A.,Lee, Dae Sung Elsevier 2018 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.349 No.-

<P><B>Abstract</B></P> <P>A simple hydrothermal treatment process was used for the fabrication of a Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB>x</SUB> (MXene) nanosheet-based hybrid photocatalyst. The chemical composition of the MXene and its derivatives (nanosize {0 0 1} facets of TiO<SUB>2</SUB> in Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB>x</SUB> (001-T/MX)), as well as the structural properties and morphology of the as-prepared photocatalyst, were well characterised. The heterostructure of the as-prepared photocatalyst was obtained by controlled oxidation action via the Schottky junction formed between TiO<SUB>2</SUB>-MXene interfaces. The adsorption/photocatalytic degradation abilities of the pristine MXene and the as-synthesised 001-T/MX nanocomposite for carbamazepine (CBZ) were investigated. The determined <I>K<SUB>app</SUB> </I> value of CBZ under ultraviolet light was 0.0304 min<SUP>−1</SUP>, higher than that under natural solar light, and the degradation capacity was strongly controlled under acidic conditions (pH 3.0–5.0). During the photocatalytic degradation, <SUP> </SUP>OH and <SUP> </SUP>O<SUB>2</SUB> attacked the CBZ molecule; detailed degradation pathways were proposed accordingly. The novel heterojunction 001-T/MX exhibited excellent applicability for CBZ decomposition.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A simple hydrothermal process is used for the fabrication of Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB>x</SUB> (MXene) nanosheets. </LI> <LI> Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB>x</SUB> MXene-based heterojunction (001-T/MX) can be used as a photocatalyst. </LI> <LI> Carbamazepine (CBZ) degradation under direct sunlight and ultraviolet light is studied. </LI> <LI> T/MX photocatalyst degrades 98.67% CBZ under UV light irradiation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Optimal Planning of Distributed Energy Storage Systems in Active Distribution Networks using Advanced Heuristic Optimization Techniques

Shahzad Kashif,Amin Arslan Ahmed 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.5

In this paper, the optimal planning of Distributed Energy Storage Systems (DESSs) in Active Distribution Networks (ADNs) has been addressed. As the proposed problem is mixed-integer, non-convex, and non-linear, this paper has used heuristic optimization techniques. In particular, fi ve optimization techniques namely Genetic algorithm, Particle swarm optimization, Tabu search, Simulated annealing, and Pattern search optimization techniques have been applied to optimal planning of DESS. The problem has been formulated to consider distributed storage units’ optimal locations and sizes to be placed in an ADN while respecting the constraints of the system. The problem has been addressed on two levels. In the fi rst level, an optimization technique is applied for DESS planning to determine the optimal solution and in the second level, the fi tness value of this solution is evaluated by solving a daily AC Optimal Power Flow (OPF) problem. Simulations have been done for the IEEE 34 and IEEE 123 nodes network to demonstrate and compare the effi ciency of diff erent optimization techniques. The comparison of these optimization techniques has shown that Particle swarm optimization and Tabu search optimization (with a particular value of tabu tenure found by hit and trial) have performed better in fi nding the lowest DESS location corresponding to minimum fi tness value as compared to other optimization techniques both for IEEE 34 nodes and IEEE 123 nodes network

An improved indirect evaporative cooler experimental investigation

Shahzad, Muhammad Wakil,Burhan, Muhammad,Ybyraiymkul, Doskhan,Oh, Seung Jin,Ng, Kim Choon ELSEVIER 2019 Applied Energy Vol. No.

<P><B>Abstract</B></P> <P>Air conditioning has enhanced the work efficiency and improved life style by maintaining comfortable environment. The growing demand of air conditioning has negative impact on energy and environment. In 2015, air conditioning consumed 6% of total global electricity produced and it is expected to increase to 20% by 2050. The leveling-off conventional chiller’s efficiency at 0.85 ± 0.03 kW/Rton due to pairing of dehumidification and cooling processes in one machine is not only the major reason of high energy consumption but also the key limitation in efficiency improvement. The de-coupling of dehumidification and cooling processes can be one of the solution to achieve the quantum jump in the performance, 0.6 ± 0.03 kW/Rton, by improving individual processes. We proposed an improved indirect evaporative cooler system for sensible cooling that can be combined with dehumidification processes to achieve sustainable cooling goals. The experimentation on 800 mm long and 280 mm wide generic cell showed that it can produce temperature differential up to 10 °C with small area of heat transfer. It was showed that the proposed vertical heat exchanger configuration with multi point injection of working air is the best configuration of the indirect evaporative cooler, achieving coefficient of performance level of 78 for cooling alone. We expect that overall coefficient of performance level of 7–8 is achievable by incorporating efficient dehumidification processes. We also presented detailed design parameters that can be used as a reference for commercial system design.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Decoupling of latent and sensible load in cooling is the key for sustainability. </LI> <LI> The indirect evaporative cooler integrated with dehumidification is one of the solution. </LI> <LI> Improved IEC with three major modification can achieve COP up to 78 for cooling only. </LI> <LI> The dehumidification system COP around 4–5 can help to achieve overall COP of 7–8. </LI> <LI> The proposed multi injection vertical heat exchanger design has the best performance. </LI> </UL> </P>