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Surface-Induced Dissociation of Low Energy H_2^(+) Impact on a Carbon Surface: A Monte Carlo Simulation

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Communications in Theoretical Physics 2011年第2期55卷 315-320页

作者： shakir Ullah A.H.Dogar A.Qayyum Physics Division Pakistan Institute of Nuclear Science and Technology

A Monte Carlo simulation based on the classical binary collision approximation is performed to investigate the interaction of W2 ions with the carbon target. The incident H2^＋ ion is characterized by its translational energy, eigenenergy and population of the vibrational state, and orientation of the ion with respect to the target surface. It is shown that experimentally determined energy resolved mass spectrum of H＋ can be nicely reproduced with the help of the proposed model. These simulations predict that translational to vibrational （T → V） energy transfer efficiency increases nonlinearly with translational energy of the incident ion. T → V energy transfer efficiency along with the initial vibrational energy of the incident H＋ ion found to play an important role in dissociation. Our simulations also show that the fraction of absorbed, reflected, and dissociated ions depends on the translational energy. The average vibrational energy of reflected H＋ increases with its initial translational energy. Moreover, average number of collisions required for dissociation varies inversely with the initial translational energy of the H2^＋.

关键词： ion-surface collisions surface-induced dissociation hydrogen molecular ions Monte Carlo simulation

Rational synthesis of carbon shell coated polyaniline/ MoS2 monolayer composites for high-performance supercapacitors

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Nano Research 2016年第4期9卷 951-962页

作者： Chao Yang Zhongxin Chen Imran shakir Yuxi Xu Hongbin Lu State Key Laboratory of Molecular Engineering of Polymers Department of Macromolecular Science Collaborative Innovation Center of Polymers and Polymer Composite Materials Fudan University Shanghai 200433 China Sustainable Energy Technologies (SET) center College of Engineering King Saud University PO-BOX 800 Riyadh 11421 Kingdom of Saudi Arabia

Conducting polymers generally show high specific capacitance but suffer from poor rate capability and rapid capacitance decary which greatly limits their practical applications in supercapacitor electrodes. To this end, many studies have focused on improving the overall capacitive performance by synthesizing nanostructured conducting polymers or by depositing a range of coatings to increase the active surface area exposed to the electrolyte and enhance the charge transport efficiency and structural stability. Despite this, simultaneously achieving high specific capacitance, good rate performance, and long cycle life remains a considerable challenge. Among the various two-dimensional （2D） layered materials, octahedral （1T） phase molybdenum disulfide （MoS2） nano- sheets have high electrical conductivity, large specific surface areas, and unique surface chemical characteristics, making them an interesting substrate for the controlled growth of nanostructured conducting polymers. This paper reports the rational synthesis of carbon shell-coated polyaniline （PANI） grown on 1T MoS2 monolayers （MoS2/PANI@C）. The composite electrode comprised of MoS2/ PANI@C with a -3 nm carbon shell exhibited a remarkable specific capacitance of up to 678 F-g-1 （1 mV.s-1）, superior capacity retention of 80% after 10,000 cycles and good rate performance （81% at 10 mV.s-1） due to the multiple synergic effects between the PANI nanostructure and 1T MoS2 substrates as well as protection by the uniform thin carbon shell. These properties are comparable to the best overall capacitive performance achieved for conducting polymers-based supercapacitor electrodes reported thus far.

关键词： supercapadtor polyaniline molybdenum disulfide carbon shell cycle stability

Dynamic evaluation of jack-up platform structure under wave, wind, earthquake and tsunami loads

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Journal of Ocean Engineering and Science 2022年第1期7卷 41-57页

作者： Zaid Mohammed Ghazi Imad shakir Abbood Farzad Hejazi Department of Civil Engineering Universiti Putra MalaysiaMalaysia Engineering Affairs Department Sunni Endowment DiwanBaghdadIraq

Nowadays,the demand for using jack-up platforms to carry out a large percentage of deep-water oil and gas exploration is steadily *** response of jack-up platforms to the severe dynamic loads that may be encountered during the structure life is not examined ***,this study attempts to investigate the response of jack-up platforms performance under the effect of dynamic loads due to wave,wind,earthquake and tsunami forces using the finite element method for two models with the lowest and highest hull *** jack-up platform is located in the Gulf of *** ac-celerations are applied to the model in high and moderate seismic *** addition,tsunami waves are applied to the platform in three different directions at 0°,45°and 90°.This study utilised Airy’s linear wave approach to assess the surface elevations and wave *** reference wind velocity is 10 knots at 10 m over the mean water *** indicate that the dynamic response of the structure is affected by the height of the platform and by the increase of the platform hull *** combination of the El-Centro earthquake,dead and live loads provides the major impact on the platform at the lowest(70 m)and highest(85 m)hull *** comparison of all result proves that the jack-up platform hull under high earthquake intensity and tsunami waves with 45°has experienced maximum ***,raising the deck will increase the response of the dynamic load and displacements but will negatively affect the platform.

关键词： Offshore structures Earthquake Dynamic excitation Jack-up platform Tsunami Seismic zone

Hypo-Driver: A Multiview Driver Fatigue and Distraction Level Detection System

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Computers, Materials & Continua 2022年第4期71卷 1999-2017页

作者： Qaisar Abbas Mostafa EAIbrahim shakir Khan Abdul Rauf Baig College of Computer and Information Sciences Imam Mohammad Ibn Saud Islamic University(IMSIU)Riyadh11432Saudi Arabia Department of Electrical Engineering Benha Faculty of EngineeringBenha UniversityQalubiaBenha13518Egypt

Traffic accidents are caused by driver fatigue or distraction in many *** prevent accidents,several low-cost hypovigilance(hypo-V)systems were developed in the past based on a multimodal-hybrid(physiological and behavioral)feature *** in this paper,real-time driver inattention and fatigue(Hypo-Driver)detection system is proposed through multi-view cameras and biosignal sensors to extract hybrid *** considered features are derived from non-intrusive sensors that are related to the changes in driving behavior and visual facial *** get enhanced visual facial features in uncontrolled environment,three cameras are deployed on multiview points(0◦,45◦,and 90◦)of the *** develop a Hypo-Driver system,the physiological signals(electroencephalography(EEG),electrocardiography(ECG),electro-myography(sEMG),and electrooculography(EOG))and behavioral information(PERCLOS70-80-90%,mouth aspect ratio(MAR),eye aspect ratio(EAR),blinking frequency(BF),head-titled ratio(HT-R))are collected and pre-processed,then followed by feature selection and fusion *** driver behaviors are classified into five stages such as normal,fatigue,visual inattention,cognitive inattention,and *** improved hypo-Driver system utilized trained behavioral features by a convolutional neural network(CNNs),recurrent neural network and long short-term memory(RNN-LSTM)model is used to extract physiological *** fusion of these features,the Hypo-Driver system is classified hypo-V into five stages based on trained layers and dropout-layer in the deep-residual neural network(DRNN)*** test the performance of a hypo-Driver system,data from 20 drivers are *** results of Hypo-Driver compared to state-of-theart methods are *** to the state-of-the-art Hypo-V system,on average,the Hypo-Driver system achieved a detection accuracy(AC)of 96.5%.The obtained results indicate that the Hypo-Driver system based on multimodal and multivie

关键词： Internet of things(IoT) intelligent transportation sensors multiview points transfer learning convolutional neural network recurrent neural network residual neural network multimodal features

A Bit-level Text Compression Scheme Based on the ACW Algorithm

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International Journal of Automation and computing 2010年第1期7卷 123-131页

作者： Hussein Al-Bahadili shakir M. Hussain Arab Academy for Banking and Financial Sciences Faculty of Information Technology Petra University

This paper presents a description and performance evaluation of a new bit-level, lossless, adaptive, and asymmetric data compression scheme that is based on the adaptive character wordlength （ACW（n）） algorithm. The proposed scheme enhances the compression ratio of the ACW（n） algorithm by dividing the binary sequence into a number of subsequences （s）, each of them satisfying the condition that the number of decimal values （d） of the n-bit length characters is equal to or less than 256. Therefore, the new scheme is referred to as ACW（n, s）, where n is the adaptive character wordlength and s is the number of subsequences. The new scheme was used to compress a number of text files from standard corpora. The obtained results demonstrate that the ACW（n, s） scheme achieves higher compression ratio than many widely used compression algorithms and it achieves a competitive performance compared to state-of-the-art compression tools.

关键词： Data compression bit-level text compression ACW(n) algorithm Huffman coding adaptive coding

A Compact Flexible Circularly Polarized Implantable Antenna for Biotelemetry Applications

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Computers, Materials & Continua 2022年第11期73卷 2457-2472页

作者： Sarosh Ahmad shakir Ullah Adnan Ghaffar Daniel Segovia Vargas Department of Signal Theory and Communications Universidad Carlos III de MadridMadrid28911Spain Department of Telecommunication Engineering University of Engineering and TechnologyPeshawar25120Pakistan Department of Electrical and Electronic Engineering Auckland University of TechnologyAuckland1010New Zealand

With the help of in-body antennas,the wireless communication among the implantable medical devices(IMDs)and exterior monitoring equipment,the telemetry system has brought us many ***,a very thin-profile circularly polarized(CP)in-body antenna,functioning in ISM band at 2.45 GHz,is proposed.A tapered coplanar waveguide(CPW)method is used to excite the *** radiator contains a pentagonal shape with five horizontal slits inside to obtain a circular polarization behavior.A bendable Roger Duroid RT5880 material(εr=2.2,tanδ=0.0009)with a typical 0.25 mm-thickness is used as a *** proposed antenna has a total volume of 21×13×0.25 *** antenna covers up a bandwidth of 2.38 to 2.53 GHz(150 MHz)in vacuum,while in skin tissue it covers 1.56 to 2.72 GHz(1.16 GHz)and in the muscle tissue covers 2.16 to 3.17 GHz(1.01 GHz).GHz).The flexion analysis in the x and y axes was also performed in simulation as the proposed antenna works with a wider bandwidth in the skin and muscle *** simulation and the curved antenna measurements turned out to be in good *** impedance bandwidth of−10 dB and the axis ratio bandwidth of 3 dB(AR)are measured on the skin and imitative gel of the pig at 27.78%and 35.5%,13.5%and 4.9%,respectively,at a frequency of 2.45 *** simulations revealed that the specific absorption rate(SAR)in the skin is 0.634 and 0.914 W/kg in muscle on *** recommended SAR values are below the limits set by the federal communications commission(FCC).Finally,the proposed low-profile implantable antenna has achieved very compact size,flexibility,lower SAR values,high gain,higher impedance and axis ratio bandwidths in the skin and muscle tissues of the human *** antenna is smaller in size and a good applicant for application in medical implants.

关键词： ISM band implantable antenna biotelemetry circularly polarized flexible antenna

Monomer-dependent synthesis of secondary amine-linked triazine-based two-dimensional polymers nanosheets

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Science China Chemistry 2020年第7期63卷 966-972页

作者： Ranran Zhao Chaoqun Niu Mohamed FAly Aboud Imran shakir Chengbing Yu Yuxi Xu School of Materials Science and Engineering Shanghai UniversityShanghai 201800China School of Engineering Westlake UniversityHangzhou 310024China Sustainable Energy Technologies Center College of EngineeringKing Saud UniversityRiyadh 11421Kingdom of Saudi Arabia

Expanding the structural diversity of crystalline two-dimensional polymers(2DPs) is highly desired but remains a considerable challenge. Herein we report the first synthesis of novel crystalline secondary amine-linked triazine-based 2DPs(SAT-2DPs) by using benzidine or 4, 4′′-diamino-p-terphenyl and cyanuric chloride under solvothermal conditions. We find the structures of diamine-based monomers play a crucial role in deciding whether the synthesized material is crystalline 2DPs nanosheets or amorphous nanoparticles, which is unexpected and provides an important understanding of the 2D polymerization *** obtained SAT-2DPs not only show a lateral size of micrometers and an ultrathin thickness of a few nanometers, but also demonstrate high crystallinity with a unique ABC stacking configuration, excellent solvent dispersibility and superior thermal stability. In addition, the resultant SAT-2DPs are used to guide uniform lithium-ion deposition due to their abundant nitrogen atoms and ordered open channels. The assembled asymmetric coin cells(Li|Cu) with SAT-2DPs realize the average coulombic efficient up to 99.3% during discharge-charge cycles. This work provides valuable insights into the synthesis of new 2DPs for various applications.

关键词： nanosheets,two-dimensional polymers crystalline solution synthesis monomer-dependent

Geometric Mean Decomposition Based Hybrid Precoding for Millimeter-Wave Massive MIMO

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China Communications 2018年第5期15卷 229-238页

作者： Tian Xie Linglong Dai Xinyu Gao Muhammad Zeeshan shakir Jianjun Li Tsinghua National Laboratory for Information Science and Technology (TNList) Department of Electronic Engineering Tsinghua University School of Engineering and Computing University of the West Scotland (UWS) The School of Electric and Information Engineering Zhongyuan University of Technology

Hybrid precoding can reduce the number of required radio frequency(RF)chains in millimeter-Wave(mmWave) massive MIMO systems. However, existing hybrid precoding based on singular value decomposition(SVD) requires the complicated bit allocation to match the different signal-to-noise-ratios(SNRs) of different sub-channels. In this paper,we propose a geometric mean decomposition(GMD)-based hybrid precoding to avoid the complicated bit allocation. Specifically,we seek a pair of analog and digital precoders sufficiently close to the unconstrained fully digital GMD precoder. To achieve this, we fix the analog precoder to design the digital precoder, and vice versa. The analog precoder is designed based on the orthogonal matching pursuit(OMP) algorithm, while GMD is used to obtain the digital precoder. Simulations show that the proposed GMD-based hybrid precoding achieves better performance than the conventional SVD-based hybrid precoding with only a slight increase in complexity.

关键词： Millimeter-wave Massive MIMO hybrid precoding geometric mean decomposition bit allocation

Impact of climate change on sediment yield for Naran watershed,Pakistan

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International Journal of Sediment Research 2016年第3期31卷 212-219页

作者： Farooq Azim Abdul Sattar shakir Habib-ur-Rehman Afshan Kanwal Centre of Excellence in Water Resource Engineering(CEWRE) University of Engineering & Technology(UET) Government College University CEWRE UET Department of Civil Engineering UET

In this paper,the site-specific impact of climate change on sediment yield has been assessed for the Naran watershed,*** data has been gathered for period 1961-2010 and HaDCM3 GCM predictors of SRES scenarios A2 and B2 have been *** precipitation and temperature time series have been statistically downscaled for time horizon 2011-2040 and *** data show both increasing and decreasing changes with respect to the *** sediment yield for future related to climate change has been *** results show that the both snowy and monsoon seasonal stream discharges are expected to *** will lead to increase in annual suspended sediment ***-wise,a less discharge and more sediment yield are expected during the early *** study concluded that the climate change and variability are influencing the watershed,and suspended sediment yield is likely to increase in the future.

关键词： Climate change Downscaling Hydrologic modeling Suspended sediment yield SHETRAN