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Space-Time Cluster Analysis of Accidental Oil Spills in Rivers State, Nigeria, 2011–2019

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Computers, Materials & Continua 2021年第3期66卷 3065-3074页

作者： Sami Ullah Hanita Daud Nooraini Zainuddin Sarat CDass alamgir khalil Hadi Fanaee-T Ilyas Khan Department of Fundamental&Applied Sciences Universiti Teknologi PETRONAS32610Seri IskandarPerakMalaysia School of Mathematical and Computer Sciences Heriot-Watt University Malaysia62200PutrajayaMalaysia Department of Statistics University of PeshawarPakistan Center for Applied Intelligent Systems Research(CAISR) Halmstad UniversityHalmstadSweden Faculty of Mathematics and Statistics Ton Duc Thang UniversityHo Chi Minh City72915Vietnam

Oil spills cause environmental pollution with a serious threat to local communities and sustainable *** oil spills can be modelled as a stochastic process where each oil spill event is described by its spatial locations and incidence-time and hence allow for space-time cluster *** cluster analysis can detect space-time pattern distribution of oil spills which can be useful for implementing preventive measures and evidence-based decision *** study aims to detect the space-time clusters of accidental oil spills in Rivers state,Nigeria through the Space-time Scan *** Space-time Scan Statistic was applied under the permutation model to the oil spill data(each for sabotage and operational oil spills)collected at Local Government Area(LGA)-level during the period from 2011 to *** results show that the sabotage oil spill clusters have covered most of the LGAs in the southern part of the state at the start of the study period and then in 2018–2019,it moved to the west covering a single *** operational oil spill clusters covered two neighboring LGAs in the *** addition,the temporal cluster of sabotage oil spills was seen in 2019 and operational oil spills in 2011–*** sabotage oil spills show an increasing trend with the maximum in 2019 while the operational oil spills show a decreasing trend with the minimum in *** findings assist in more effective decision-making for combating the environmental problems and controlling the future spill incidence in the cluster-regions.

关键词： Oil spills space-time clusters SaTScan^(™) permutation model Nigeria

Robust Stabilization of Non-minimum Phase Switched Nonlinear Systems with Uncertainty

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Journal of Systems Science & Complexity 2020年第2期33卷 289-311页

作者： khalil Jouili Laboratory of Advanced Systems Polytechnic School of Tunisia(EPT) B.P.7432078 MarsaTunisia

This paper investigates the problem of robust stabilization of a class of switched nonlinear system with uncertain dynamics where each subsystem represents a non-minimum *** authors first construct a stabilizing sliding mode controller for each subsystem to stabilize individually its own unstable internal ***,a switching strategy is introduced to select the most appropriate diffeomorphism through an infinity of *** conditions are specifically given for the exponential stability and the exponential upper bound of the trajectory of the switched subsystem,which guarantees the global asymptotical stability of the resulting switched ***,the proposed control approach can improvemore the transient state,compared to a feedback linearization based on only one *** studies illustrate the effectiveness of the suggested approach.

关键词： Exponential stability sliding mode control switching control uncertain non-minimum phase systems

Mechanical wet-milling and subsequent consolidation of ultra-fine Al_2O_3-(ZrO_2+3%Y_2O_3) bioceramics by using high-frequency induction heat sintering

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中国有色金属学会会刊：英文版 2007年第1期17卷 21-26页

作者： khalil Abdelrazek khalil Sug Won KIM Division of Advanced Materials Engineering RIAMD Chonbuk National University

Alumina/zirconia composites were synthesized by wet-milling technique and rapid consolidation with high frequency induction heat sintering(HFIHS). The starting materials were a mixture of alumina micro-powder (80%, volume fraction) and 3YSZ nano-powders (20%). The mixtures were optimized for good sintering behaviors and mechanical properties. Nano-crystalline grains are obtained after 24 h milling. The nano-structured powder compacts are then processed to full density at different temperatures by HFIHS. Effects of temperature on the mechanical and microstructure properties were studied. Al2O3-3YSZ composites with higher mechanical properties and small grain size are successfully developed at relatively low temperatures through this technique.

关键词：生物陶瓷烧结工艺高频诱导微观结构机械性能

POLYMERIZATION OF N,N'-(PYROMELLITOYL)-BIS-L-LEUCINE DIACID CHLORIDE WITH HYDANTOIN DERIVATIVES BY MICROWAVE IRRADIATION

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Chinese Journal of Polymer Science 2004年第4期22卷 343-348页

作者： khalil Faghihi Organic Polymer Chemistry Research Laboratory Department of Chemistry Faculty of Science Arak University Arak 38156 Iran

Facile and rapid polycondensation reactions of N,N'-(pyromellitoyl)-bis-L-leucine diacid chloride 1 with eight different derivatives of hydantoin compounds 2a-h were developed by using a domestic microwave oven in the presence of a small amount of polar organic medium such as o-cresol. The polycondensation reactions proceeded rapidly, compared with the conventional solution polycondensation, and was completed within 7-10 min, producing a series of novel optically active poly(amide-imide)s 3a-h with high yield and inherent viscosity of 0.35-0.65 dL/g. All of the above polymers were fully characterized by FT-IR, elemental analyses, inherent viscosity (η inh ), solubility test and specific rotation. Some structural characterization and physical properties of these optically active poly(amide-imide)s are reported.

关键词： Microwave-assisted rapid polycondensation Optically active polymers Poly(amide-imide)s Hydantoin derivatives N,N'-(Pyromellitoyl)-bis-L-leucine diacid chloride

SYNTHESIS AND CHARACTERIZATION OF OPTICALLY ACTIVE POLY(AMIDE-IMIDE)S CONTAINING PHOTOSENSITIVE CHALCONE UNITS IN THE MAIN CHAIN

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Chinese Journal of Polymer Science 2010年第5期28卷 695-704页

作者： khalil Faghihi Hassan Moghanian Organic Polymer Chemistry Research Laboratory Department of ChemistryFaculty of ScienceArak UniversityArak 38156Iran

A series of new optically active poly（amide-imide）s were synthesized by direct polycondensation reaction of 4,4＇-diaminochalcone with several N-trimellitylimido-L-amino acids using a tosyl chloride （TsCl）, pyridine （Py） and dimethylformamide （DMF） system as condensing agent. The resulting thermally stable poly（amide-imide）s were obtained in good to high yields and inherent viscosities ranging between 0.35 dL/g and 0.58 dL/g and were characterized with FTIR, IH-NMR, CHN, Ultraviolet, TGA and DTG techniques.

关键词： Poly(amide-imide)s Chalcone moeity Polycondensation Optically active polymers.

New optically active poly(amide-imide)s derived from N,N'-(4,4-diphthaloyl)-bis-L-leucine and hydantoin derivatives:Synthesis and properties

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Chinese Chemical Letters 2009年第10期20卷 1153-1156页

作者： khalil Faghihi Polymer Chemistry Research Laboratory Department of ChemistryFaculty of ScienceIslamic Azad UniversityArak BranchArakIran

Six new optically active poly（amide-imide）s （5a-f） were synthesized through the direct polycondensation reaction of N,N′-（4,4′- diphthaloyl）-bis-L-leucine （3） with six hydantoin derivatives （4a-f）. Tripbenyl phosphite （TPP）/pyridine in the presence of calcium chloride （CaCl2） and N-methyl-2-pyrrolidone （NMP） were successfully applied for direct polycondensation. The polycondensation reactions produce a series of new poly（amide-imide）s （5a-f） in high yields, and inherent viscosity between 0.42 and 0,55 dL/g. The resulting poly（amide-imide）s （5a-f） were characterized by elemental analysis, viscosity measurements, thermal gravimetric analysis （TGA and DTG）, solubility test and FT-IR spectroscopy.

关键词： High performance polymers Poly(amide-imide)s Direct polycondensation Hydantoin derivatives

Electromagnetic effects on the orbital motion of a charged spacecraft

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Research in Astronomy and Astrophysics 2014年第5期14卷 589-600页

作者： Yehia Ahmed Abdel-Aziz khalil Ibrahim khalil National Research Institute of Astronomy and Geophysics (NRIAG) Helwan Cairo 11721Egypt Department of Mathematics Hail University Hail 2440 Kingdom of Saudi Arabia

This paper deals with the effects of electromagnetic forces on the orbital motion of a spacecraft. The electrostatic charge which a spacecraft generates on its surface in the Earth＇s magnetic field will be subject to a perturbative Lorentz force. A model incorporating all Lorentz forces as a function of orbital elements has been developed on the basis of magnetic and electric fields. This Lorentz force can be used to modify or perturb the spacecraft＇s orbits. Lagrange＇s planetary equations in the Gauss variational form are derived using the Lorentz force as a perturbation to a Keplerian orbit. Our approach incorporates orbital inclination and the true anomaly. The numer- ical results of Lagrange＇s planetary equations for some operational satellites show that the perturbation in the orbital elements of the spacecraft is a second order perturba- tion for a certain value of charge. The effect of the Lorentz force due to its magnetic component is three times that of the Lorentz force due to its electric component. In addition, the numerical results confirm that the strong effects are due to the Lorentz force in a polar orbit, which is consistent with realistic physical phenomena that occur in polar orbits. The results confirm that the magnitude of the Lorentz force depends on the amount of charge. This means that we can use artificial charging to create a force to control the attitude and orbital motion of a spacecraft.

关键词： space vehicles -- atmospheric effects -- celestial mechanics -- kine-matics and dynamics

RAPID SYNTHESIS OF NOVEL OPTICALLY ACTIVE POLY(AMIDE-IMIDE)S DERIVED FROM N,N'-(PYROMELLITOYL)-BIS-L-ALANINE DIACID CHLORIDE AND HYDANTOIN DERIVATIVES UNDER MICROWAVE IRRADIATION

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Chinese Journal of Polymer Science 2005年第1期23卷 63-69页

作者： khalil Faghihi Azizollah Mirsamie Organic Polymer Chemistry Research Laboratory Department of ChemistryFaculty of ScienceArak UniversityArak38156Iran Chemical Engineering DeptFaculty of EngineeringAzad Univertsity of ArakArakIran Organic Polymer Chemistry Research LaboratoryDepartment of ChemistryFaculty of ScienceArak UniversityArak38156Iran

Eight novel poly(amide-imide)s were synthesized under microwave irradiation by using a domestic microwaveoven from the polycondensation reactions of N.N'-(pyromellitoyl)-bis-L-alanine diacid chloride(1)with eight differentderivatives of hydantoin compounds(2a-h)in the presence of a small amount of a polar organic medium such as *** polycondensation proceeded rapidly,compared with the conventional solution polycondensation and was completedwithin 8-10 min,producing a series of new poly(amide-imide)s(3a-h)with inherent viscosities about 0.35-0.68 dL/g inhigh *** obtained PAIs(3a-h)were fully characterized by means of FT-IR spectroscopy,elemental analyses,inherentviscosity(ηinh),solubility and specific rotation *** of the resulting polymers show optical rotation and areoptically *** properties of the poly(amide-imide)s were investigated by using thermal gravimetric analysis(TGA).

关键词： Microwave-assisted polycondensation Optically active polymers 5,5-Disubstituted hydantoin derivatives.

OPTICALLY ACTIVE AND FLAME-RETARDANT POLY(AMIDE-IMIDE)S BASED ON PHOSPHINE OXIDE MOIETY AND N,N′-(PYROMELLITOYL)BIS-L-AMINO ACID IN THE MAIN CHAIN:SYNTHESIS AND CHARACTERIZATION

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Chinese Journal of Polymer Science 2010年第4期28卷 517-525页

作者： khalil Faghihi Mohsen Hajibeygi Organic Polymer Chemistry Research Laboratory Department of ChemistryFaculty of ScienceArak UniversityArak 38156Iran

Six new optically active and flame-retardant poly（amide-imide）s PAls 5a-5f containing phosphine oxide moiety as a flame-retardant unit in the main chain were synthesized from direct polycondensation reaction of six chiral N,N＇-（pyromellitoyl）-bis-L-amino acid 3a-3f with bis（3-aminophenyl）phenyl phosphine oxide 4 in a medium consisting of N-methyl-2-pyrrolidone （NMP）, triphenyl phosphite （TPP）, calcium chloride （CaCl2） and pyridine. The polymerization reactions produced a series of optically active poly（amide-imide）s with good yield and good inherent viscosity of 0.34-0.70 dLg^-1. The resulted polymers were fully characterized by means of FTIR and ^1H-NMR spectroscopy, gel permeation chromatography （GPC）, elemental analyses, inherent viscosity and solubility tests. Thermal properties and flameretardant behavior of the PAIs 5a-5f were investigated using thermal gravimetric analysis （TGA and DTG） and limiting oxygen index （LOI）. Data obtained by thermal analysis （TGA and DTG） revealed that these polymers showed good thermal stability. Furthermore, high char yield in TGA and good LOI values indicated that the resulting polymers were capable of exhibiting good flame retardant properties. N,N＇-（pyromellitoyl）-bis-L-amino acids 3a-3f were prepared in quantitative yields by the condensation reaction of pyromellitic dianhydride （1,2,4,5-benzenetetracarboxylicacid-1,2,4,5-dianhydride） 1 with L-alanine 2a, L-valine 2b, L-leucine 2c, L-isoleucine 2d, L-phenyl alanine 2e and L-2-aminobutyric acid 2f in acetic acid solution.

关键词： Optically active Flame-retardant polymers Poly(amide-imide)s Limiting oxygen index