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.

Nafion-stabilized two-dimensional transition metal carbide (Ti₃C₂T_x MXene) as a high-performance electrochemical sensor for neurotransmitter

Shahzad, Faisal,Iqbal, Aamir,Zaidi, Shabi Abbas,Hwang, Suk-Won,Koo, Chong Min Elsevier 2019 Journal of industrial and engineering chemistry Vol.79 No.-

<P><B>Abstract</B></P> <P>Herein, we demonstrate the selective sensing of Dopamine (DA), an important neurotransmitter, by using Nafion-stabilized two-dimensional transition metal carbides (Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB>x</SUB> MXenes). Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB>x</SUB> was deposited on a glassy carbon electrode followed by Nafion coating to achieve a robust sensitivity (∼3nM), good selectivity, wide detection window (0.015–10μM), high stability, reproducibility, and outstanding recoveries for DA detection in real samples. MXene-based biosensor exhibited much better electrochemical performance when compared with reduced graphene oxide-based biosensor under similar experimental conditions due to the MXenes good electrical conductivity and negatively charged surface which assisted in the selective and sensitive detection of DA.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Numerical study of the existence criterion for the reversed shear Alfven eigenmode in the presence of a parallel equilibrium current

Shahzad, M.,Rizvi, H.,Panwar, A.,Ryu, C. M. American Institute of Physics, 2017 Physics of plasmas Vol.24 No.6

Enhancing the Tomato Seed Germination and Seedling Vigor by Osmopriming

Shahzad M. Basra,Muhammad Farooq,Irfan Afzal,Basharat A. Saleem 한국원예학회 2006 한국원예학회 기타간행물 Vol.- No.-

An Improved Method of Organogenesis from Cotyledon Callus of Acacia sinuata (Lour.) Merr. using Thidiazuron

Shahzad Anwar,Ahmad Naseem,Anis Mohammad The Korean Society of Plant Biotechnology 2006 Plant molecular biology and biotechnology research Vol.8 No.1

An efficient protocol for in vitro multiple shoot bud induction and plant regeneration from mature green cotyledon derived callus tissues of Acacia sinuata has been developed. Callus formation occurs at all the concentrations of thidiazuron (TDZ) in Murashige and Skoog's (MS) medium, but 0.6 ${\mu}M$ proved to be the best with maximum callus formation frequency. Supplementation of TDZ in combination with indole-acetic acid (IAA) in MS media accelerates shoot bud organogenesis in differentiating callus tissues with 60-70% conversion of shoot buds into shoot Most efficient shoot organogenesis was recorded when TDZ induced calli were subcultured at different concentrations of 6-benzyla-denine (BA). Optimum shoot bud induction and plant regeneration from callus was achieved when 0.6 ${\mu}M$ (TDZ) induced calli were subcultured at 3.0 ${\mu}M$ (BA) where $16.6{\pm}0.74$ shoots/unit callus on obtained. Rooting in in vitro differentiated shoots was achieved when transferred to medium containing different concentration of indole-3-butyric acid (IBA) in full & half strength MS medium. The well rooted plantlets were hardened and transferred to net house with 90% survival rate.

Comment on 'An ultrathin stretchable triboelectric nanogenerator with coplanar electrode for energy harvesting and gesture sensing' by X. Chen, Y. Song, H. Chen, J. Zhang and H. Zhang, Journal of Materials Chemistry A, 2017, 5, 12361

Shahzad, A.,Wijewardhana, K. R.,Song, J. K. Royal Society of Chemistry 2017 Journal of Materials Chemistry A Vol.5 No.45

<P>Chen et al. suggested a skin- contact type triboelectric energy harvesting device [Chen et al., J. Mater. Chem. A, 2017, 5, 12361], which can give a rise to an electrostatic charge issue adversely affecting a person's physical experience. Here we show that adoption of a higher ranking triboelectric material than skin on the positive electrode and size optimisation of the two electrodes can ensure both high power generation and resolution of the electrostatic charge issue.</P>

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>

Synthesis of Multifunctional Electrically Tunable Fluorine-Doped Reduced Graphene Oxide at Low Temperatures

Shahzad, Faisal,Zaidi, Shabi Abbas,Koo, Chong Min American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.28

<P>Doping with heteroatoms is a well-established method to tune the electronic properties and surface chemistry of graphene. Herein, we demonstrate the synthesis of a fluorine-doped reduced graphene oxide (FrGO) at low temperatures that offers multiple opportunities in applied fields. The as-synthesized FrGO product shows a better electrical conductivity of 750 S m(-1) than that of undoped rGO with an electrical conductivity of 195 S m(-1). To demonstrate the multifunctional applications of the as-synthesized FrGO, it was examined for electromagnetic interference shielding and electrochemical sensing of histamine as an important food biomarker. A laminate of FrGO delivered an EMI shielding effectiveness value of 22 dB in Ku band as compared with 11.2 dB for an rGO laminate with similar thickness. On the other hand, an FrGO modified sensor offered an excellent sensitivity (similar to 7 nM), wide detection range, and good selectivity in the presence of similar biomarkers. This performance originates from the better catalytic ability of FrGO as compared with rGO, where fluorine atoms play the role of catalytic active sites owing to their high electronegativity. The fluorination reaction also helps to improve the reduction degree of the chemically synthesized graphene, consequently enhancing the electrical conductivity, which is a prime requirement for increasing the electromagnetic and electrochemical properties of graphene.</P>

Beam deflector and position sensor using electrowetting and mechanical wetting of sandwiched droplets

Shahzad, Amir,Song, Jang-Kun IOP 2016 Journal of Physics. D, Applied Physics Vol.49 No.38

<P>Electrowetting (EW) offers a facile manipulation of a liquid droplet on a surface, and several different systems have been suggested to utilize EW on various applications. In this letter, the manipulation of an electrolyte droplet with a floating movable substrate was investigated on a solid substrate. Two types of approaches were made; firstly, we controlled the vertical position of a floating substrate using EW property of droplets. The tilting angle of a floating substrate can be precisely controlled along two orthogonal directions independently, which can be used to devise a beam deflector. In the other case, mechanical wetting of droplets via external pressure was used to detect the position of a floating substrate; this position sensor has at least four orders of magnitude higher sensitivity than the conventional position sensor based on capacitance.</P>

Foliar application of methyl jasmonate induced physio-hormonal changes in Pisum sativum under diverse temperature regimes

Shahzad, R.,Waqas, M.,Khan, A.L.,Hamayun, M.,Kang, S.M.,Lee, I.J. Gauthier-Villars ; Elsevier Science Ltd 2015 Vol. No.

Global climate change brings with it unwarranted shifts in both abiotic (heat stress, cold stress, wind, precipitation) and biotic (pathogens, pests) environmental factors, thus posing a threat to agricultural productivity across the world. In plants, lodging due to storms or herbivory causes wounding stress and consequently enhances endogenous jasmonates. In response, the plant growth is arrested as plant defense is prioritized. We pre-treated pea plants with elevated methyl jasmonate (MeJA) levels i.e. 50 μM, 100 μM and 200 μM under controlled growth chamber conditions. The pre-treated plants were then kept at 40 <SUP>o</SUP>C (heat stress-HS), 4 <SUP>o</SUP>C (cold stress-CS) and 20 <SUP>o</SUP>C (optimum/control temperature-OT) for 72 h. The effect of such treatments on plant growth attributes, photosynthesis, stomatal conductance, cell death rate, and regulation of endogenous hormones were observed. Elevated MeJA application hindered plant growth attributes under HS, CS and OT conditions. Moreover, elevated MeJA levels lowered the rate of photosynthesis and stomatal conductance, induced stomatal closure, caused higher cells mortality in leaves under HS, CS, and OT conditions. Endogenous ABA contents significantly declined in all MeJA treatments under HS and OT, but increased under CS conditions. Exogenous MeJA enhanced endogenous jasmonic acid contents of pea plants, but altered endogenous salicylic acid contents under varying temperatures. Current study shows that higher concentrations of exogenous MeJA strengthen plant defense mechanism by hindering plant growth under stress conditions.