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71.
In this paper we consider a model for the motion of incompressible viscous flows proposed by Ladyzhenskaya. The Ladyzhenskaya model is written in terms of the velocity and pressure while the studied model is written in terms of the streamfunction only. We derived the streamfunction equation of the Ladyzhenskaya model and present a weak formulation and show that this formulation is equivalent to the velocity–pressure formulation. We also present some existence and uniqueness results for the model. Finite element approximation procedures are presented. The discrete problem is proposed to be well posed and stable. Some error estimates are derived. We consider the 2D driven cavity flow problem and provide graphs which illustrate differences between the approximation procedure presented here and the approximation for the streamfunction form of the Navier–Stokes equations. Streamfunction contours are also displayed showing the main features of the flow. 相似文献
72.
The short-range atomic order around all three constituent atoms in a prototypical bulk metallic glass (BMG) system was probed in a complementary way, using extended X-ray absorption fine structure for neighborhood of the higher atomic number elements, and extended energy loss fine structure (EXELFS) for the lower atomic number ones. The PdxNi(80−x)P(20) system is a prototype for a whole class of BMG formers which are 80% transition metal and 20% metalloid. We find that the structure of these BMGs could be explained in terms of those of glasses at the end of the BMG range, namely, Pd60Ni20P20 and Pd30Ni50P20. The binary phosphide crystals near x=0 and 80 are found to be simulate very well the local atomic structure of Pd30Ni50P20 and Pd60Ni20P20 glasses, respectively. The best glass former in this series, Pd40Ni40P20, is best described by a weighted average of Pd30Ni50P20 and Pd60Ni20P20 structures. 相似文献
73.
We show that the recently reported momentum distribution of recoil ions from laser induced nonsequential double ionization can be interpreted as a combined effect of interelectron correlation and final state field interaction ("Volkov dressing") of the two outgoing electrons. We also find a cutoff formula for the recoil momentum that gives the maximum momenta observed in the experiments. 相似文献
74.
F.H.M. Faisal 《Physics letters. A》1977,60(4):295-296
The exact solution of the adiabatic following pulse propagation equations describing coherent propagation of a single-photon quasi-resonant short pulse of arbitrary shape and phase is reported. 相似文献
75.
Analyses of two mechanisms of double ionization of He in an intense femtosecond laser pulse are made within the S-matrix theory. Their contributions are compared with each other and with the recent data of coincidence measurements for two-electron energy distributions. It is found that the correlated energy-sharing mechanism reproduces the data remarkably well and also confirms the so-called "excessive production" of hot electrons in the process. In contrast, the shakeoff mechanism is found to fail completely to account for either the strength or the trend of the data and is therefore ruled out. 相似文献
76.
Maha Abdallah Alnuwaiser M. Faisal Javed M. Ijaz Khan M. Waqar Ahmed Ahmed M. Galal 《印度化学会志》2022,99(7):100538
The current study investigates the potential of well-known artificial neural network (ANN), Support vector regression (SVR), multilinear and multi-nonlinear regression techniques to predict total dissolve solids (TSO) and electrical conductivity (ECO), which are essential water quality indicators. To develop the anticipated models, seven effective parameters: Ca2+ Mg2+ Na+ Cl- SO42- HCO3- and pH were used as input variables. The external validation criteria were employed to address the modeling overfitting. The outcome of the study demonstrated a strong association between experimental and models predicted data. The coefficient of determination was 0.97, 0.96, 0.92, and 0.94 for SVR, ANN, MLR, and MNLR models, respectively. The lowest error value of 5.37 and 7.92 was attained by SVR model for training and testing data, respectively. Performance of the proposed techniques showed relative dominance of SVR compared to ANN, MLR and MNLR. Sensitivity analysis demonstrated that the HCO3- is the most sensitive parameter for both TSO and ECO followed by Cl- and SO42-. The models assessment on external criteria ensured generalized results. Conclusively, the outcome of the present research indicated that formulation of machine learning models for prediction of water quality parameters are cost effective and helpful in river water quality assessment, management and policy making. 相似文献
77.
78.
Basir Md. Faisal Md. Mabood Fazle Satya Narayana P. V. Venkateswarlu B. Ismail Ahmad Izani Md. 《Journal of Thermal Analysis and Calorimetry》2022,147(1):661-674
Journal of Thermal Analysis and Calorimetry - The enhancement of heat transfer in a new kind of hybrid nanofluid is more than that of a single nanoparticle. Also, the thermal conductivity of... 相似文献
79.
Muhammad Faisal Danish Shahzad Aamer Saeed Bhajan Lal Shomaila Saeed Fayaz Ali Larik Pervaiz Ali Channar Parvez Ali Mahesar Jamaluddin Mahar 《Tetrahedron: Asymmetry》2017,28(11):1445-1461
Isoquinuclidines constitute the central structural nucleus of numerous biologically active natural products, for example, iboga alkaloids such as ibogamine and catharanthine as well as non-indole-containing alkaloids such as the dioscorine and the cannivonines. Furthermore, in medicinal and pharmaceutical chemistry, the isoquinuclidine core is commonly employed as a rigid azabicyclic scaffold, thus providing significant precursors in the synthesis of numerous valuable alkaloids. Summarizing well-organized approaches to access the chiral isoquinuclidine structural centerpiece signifies a significant endeavor not only for developing biologically active natural products but also enhancing biological researches that can lead to possible drug discovery. Over time, the values and methodologies for the asymmetric synthesis of chiral isoquinuclidines are increasing; hence to advance asymmetric synthesis, this review combines and discusses the pros and cons of each synthesis techniques from 2008. This review should be helpful for promoting further developments of asymmetric synthetic methodologies and for medicinal chemistry. 相似文献
80.
Rosenani A. Haque Patrick O. Asekunowo Mohd. R. Razali Faisal Mohamad 《Heteroatom Chemistry》2014,25(3):194-204
A series of N‐heterocyclic carbene (NHC) precursors, 1‐methoxylethyl‐3‐allylimidazolium hexafluorophosphate ( 1 ), 1‐ethyl‐3‐allylimidazolium hexafluorophosphate ( 2 ), and 1‐pentyl‐3‐allylimidazolium hexafluorophosphate ( 3 ) were synthesized. These salts were treated with Ag2O to afford their corresponding mononuclear Ag(I)‐NHC complexes, namely 1‐methoxylethyl‐3‐allylimidazolium silver(I) hexafluorophosphate ( 4 ), 1‐ethyl‐3‐allylimidazolium silver(I) hexafluorophosphate ( 5 ), and 1‐pentyl‐3‐allylimidazolium silver(I) hexafluorophosphate ( 6 ), respectively. These compounds were characterized by physicochemical and spectroscopy techniques. Compounds 4 and 5 were structurally characterized by single crystal X‐ray diffraction, and their stability in solution was investigated and found to be acceptable for the antibacterial studies. These new NHC precursors and their respective Ag–NHC complexes were screened for their antibacterial activities against Staphylococcus aureus (ATCC 12600) and Escherichia coli (ATCC 25922). Compounds 1–3 showed no inhibition, whereas 4–6 inhibited the growth of these bacteria. The nuclease activities of the reported compounds against plasmid DNA and RNA were assessed by gel electrophoresis, and the results indicate that complexes 5 and 6 can degrade both DNA and RNA in the absence of an oxidant. 相似文献