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Proceedings of the Institution of Mechanical Engineers Part N-Journal of Nanomaterials Nanoengineering and Nanosystems最新文献

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Spontaneously generated coherence in ladder-plus-Y double quantum dot system 阶梯+ y双量子点系统的自发相干
B. Al-Nashy, Sabeah Jasim, A. G. Al-Shatravi, A. Al-khursan
A model was presented for linear susceptibility in ladder-plus-Y configuration of double quantum dot system using density matrix theory and including spontaneously generated coherence of Λ-type system. Wetting layer and quantum dot inhomogeneity were considered in the calculations, which gives a practical description of double quantum dot structures well. With increasing spontaneously generated coherence from Λ-component, the dispersion was increased and shifted under spontaneously generated coherence. The inclusion of wetting layer under spontaneously generated coherence increases gain which coincides with the published results. A possibility of slow light was predicted.
利用密度矩阵理论,考虑Λ-type系统的自发相干性,建立了双量子点系统阶梯+ y结构的线性磁化率模型。计算中考虑了湿润层和量子点的非均匀性,较好地描述了双量子点结构。随着自发相干度Λ-component的增大,自发相干度下色散增大,色散移位。在自发相干下加入润湿层增加了增益,这与已发表的结果一致。有人预测可能存在慢光。
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引用次数: 1
Numerical investigation of viscoelastic nanofluid flow with radiation effects 考虑辐射效应的粘弹性纳米流体流动数值研究
A. Hussain, Lubna Sarwar, Sobia Akbar, S Nadeem, Sarmad Jamal
In this article, the fully developed steady state flow of an incompressible fluid pertained to as viscoelastic nanofluid model with radiation effects through a penetrable plate is studied. Continuity, momentum and energy equations are elaborated to comprehend the nature of the fluid flow. By using similarity transformations, the solution of arising governing equations is obtained numerically with the assistance of a shooting technique. Furthermore, the consequences of different parameters, that is, Brownian motion parameter, Weissenberg number, thermophoresis parameter, permeability parameter, non-Newtonian parameter and radiation parameter on concentration, velocity and temperature fields, are canvassed with the help of graphs. The effects of Pr and γ on Nusselt number and N b and γ on Sherwood number are also discussed with the assistance of graphs and tables for different values of dimensionless parameters.
本文研究了具有辐射效应的不可压缩流体的粘弹性纳米流体模型的完全发展的稳态流动。阐述了连续性、动量和能量方程,以理解流体流动的性质。利用相似变换,在射击技术的辅助下,用数值方法得到了产生的控制方程的解。此外,还利用图形分析了布朗运动参数、Weissenberg数、热泳态参数、渗透率参数、非牛顿参数和辐射参数对浓度、速度和温度场的影响。本文还讨论了Pr和γ对Nusselt数的影响以及nb和γ对Sherwood数的影响。
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引用次数: 17
Computational study of unsteady couple stress magnetic nanofluid flow from a stretching sheet with Ohmic dissipation 非定常耦合应力磁性纳米流体在具有欧姆耗散的拉伸片上流动的计算研究
Mahesh Kumar, G. J. Reddy, N. N. Kumar, O. Bég
To provide a deeper insight of the transport phenomena inherent to the manufacturing of magnetic nano-polymer materials, in the present work a mathematical model is developed for time-dependent hydromagnetic rheological nano-polymer boundary layer flow and heat transfer over a stretching sheet in the presence of a transverse static magnetic field. Joule heating (Ohmic dissipation) and viscous heating effects are included since these phenomena arise frequently in magnetic materials processing. Stokes’ couple stress model is deployed to simulate non-Newtonian microstructural characteristics. The Tiwari–Das nanoscale model is adopted which permits different nanoparticles to be simulated (in this article, both copper–water and aluminium oxide–water nanofluids are considered). Similarity transformations are utilized to convert the governing partial differential conservation equations into a system of coupled, non-linear ordinary differential equations with appropriate wall and free stream boundary conditions. The shooting technique is used to solve the reduced non-linear coupled ordinary differential boundary value problem via MATLAB symbolic software. Validation with published results from the literature is included for the special cases of non-dissipative and Newtonian nanofluid flows. Fluid velocity and temperature profiles for both copper and aluminium oxide (Al2O3) nanofluids are observed to be enhanced with greater non-Newtonian couple stress parameter and magnetic parameter, whereas the opposite trend is computed with greater values of unsteadiness parameter. The boundary layer flow is accelerated with increasing buoyancy parameter, elastic sheet stretching parameter and convection parameter. Temperatures are generally increased with greater couple stress rheological parameter and are consistently higher for the aluminium oxide nanoparticle case. Temperatures are also boosted with magnetic parameter and exhibit an overshoot near the wall when magnetic parameter exceeds unity (magnetic force exceeds viscous force). A decrease in temperatures is induced with increasing sheet stretching parameter. Increasing Eckert number elevates temperatures considerably. With greater nanoparticle volume fraction, both skin friction and Nusselt number are elevated, and copper nanoparticles achieve higher magnitudes than aluminium oxide.
为了更深入地了解磁性纳米聚合物材料制造中固有的输运现象,在本研究中,我们建立了一个数学模型,用于研究在横向静态磁场存在下拉伸片上随时间变化的流体磁流变纳米聚合物边界层流动和热传递。焦耳加热(欧姆耗散)和粘性热效应也包括在内,因为这些现象在磁性材料加工中经常出现。采用Stokes耦合应力模型模拟非牛顿微观结构特征。采用Tiwari-Das纳米尺度模型,该模型允许模拟不同的纳米颗粒(在本文中,铜-水和氧化铝-水纳米流体都被考虑在内)。利用相似变换将控制偏微分守恒方程转换为具有适当壁面和自由流边界条件的耦合非线性常微分方程系统。采用射击技术,通过MATLAB符号软件求解简化非线性耦合常微分边值问题。验证与发表的结果,从文献包括非耗散和牛顿纳米流体流动的特殊情况。当非牛顿耦合应力参数和磁参数较大时,铜和氧化铝纳米流体的速度和温度曲线均增强,而非定常参数较大时,流体速度和温度曲线则相反。边界层流动随着浮力参数、弹性板拉伸参数和对流参数的增大而加速。温度通常随耦合应力流变参数的增大而升高,并且氧化铝纳米颗粒的温度始终较高。温度也随着磁性参数的增加而升高,当磁性参数超过单位(磁力超过粘性力)时,温度在壁面附近出现超调。随着板材拉伸参数的增大,温度降低。埃克特数的增加使温度显著升高。随着纳米颗粒体积分数的增加,表面摩擦和努塞尔数都增加,并且铜纳米颗粒达到比氧化铝更高的量级。
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引用次数: 20
Modeling magnetic nanopolymer flow with induction and nanoparticle solid volume fraction effects: Solar magnetic nanopolymer fabrication simulation 基于感应和纳米颗粒固体体积分数效应的磁性纳米聚合物流动建模:太阳能磁性纳米聚合物制造模拟
O. Bég, S. Kuharat, M. Ferdows, M. Das, A. Kadir, M. Shamshuddin
A mathematical model is presented for the nonlinear steady, forced convection, hydromagnetic flow of electro-conductive magnetic nanopolymer with magnetic induction effects included. The transformed two-parameter, non-dimensional governing partial differential equations for mass, momentum, magnetic induction and heat conservation are solved with the local non-similarity method subject to appropriate boundary conditions. Keller’s implicit finite difference “box” method is used to validate solutions. Computations for four different nanoparticles and three different base fluids are included. Silver nanoparticles in combination with various base fluids enhance temperatures and induced magnetic field and accelerate the flow. An elevation in magnetic body force number decelerates the flow, whereas an increase in magnetic Prandtl number elevates the magnetic induction. Furthermore, increasing nanoparticle solid volume fraction is found to substantially boost temperatures. Applications of the study arise in advanced magnetic solar nanomaterials (fluids) processing technologies.
建立了考虑磁感应效应的导电磁性纳米聚合物非线性稳态、强制对流、流体磁感应流动的数学模型。在适当的边界条件下,用局部非相似法求解转化后的质量、动量、磁感应和热守恒的双参数无量纲控制偏微分方程。Keller的隐式有限差分“盒”法用于验证解。计算四种不同的纳米粒子和三种不同的基础流体包括在内。银纳米颗粒与各种基液结合,提高温度和感应磁场,加速流动。磁体力数的增加使流动减速,而磁普朗特数的增加使磁感应强度增大。此外,增加纳米颗粒固体体积分数可以显著提高温度。该研究的应用出现在先进的磁性太阳能纳米材料(流体)加工技术。
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引用次数: 30
Characterization of CuO-doped tin dioxide thin films prepared by pulsed-laser deposition for gas-sensing applications 气敏用脉冲激光沉积法制备cuo掺杂二氧化锡薄膜的表征
I. Naji
The influence of doping level of tin oxide films with different amounts of CuO additives (5%, 10%, 15%, and 20%) on structural, optical, and electrical properties is investigated. The films were prepared by pulsed-laser deposition method. X-ray diffraction patterns show the polycrystalline structure for all films with tetragonal phase for SnO2 and monoclinic phase for CuO, and no reaction between them. The surface morphology of films was analyzed and it revealed nano-sized grains for samples doped with 10% and 15% CuO. Hall’s effect measurements show increasing conductivity with increase in the CuO ratio and transfer the type of charge carriers from n- to p-type with 20% CuO. The H2S sensing properties are influenced by the CuO ratio in the SnO2 films as well as the operation temperature. The SnO2 sensor loaded with 10% CuO is extremely sensitive to H2S and the best operation temperature is 50°C, and it exhibits fast response speed of 7 s and recovery time of 20 s for trace level (10 ppm) H2S gas detection.
研究了不同CuO添加量(5%、10%、15%和20%)对氧化锡薄膜结构、光学和电学性能的影响。采用脉冲激光沉积法制备薄膜。x射线衍射图显示,所有薄膜均为多晶结构,SnO2为四方相,CuO为单斜相,两者之间无反应。对薄膜的表面形貌进行了分析,发现掺10%和15% CuO的样品具有纳米级晶粒。霍尔效应测量表明,随着CuO比的增加,电导率增加,20% CuO时载流子类型从n型转移到p型。SnO2薄膜中CuO比和操作温度对H2S传感性能有影响。负载10% CuO的SnO2传感器对H2S非常敏感,最佳工作温度为50℃,对痕量(10 ppm) H2S气体检测的响应速度为7 s,恢复时间为20 s。
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引用次数: 4
Temperature effects on the interfacial behavior of functionalized carbon nanotube–polyethylene nanocomposite using molecular dynamics simulation 温度对功能化碳纳米管-聚乙烯纳米复合材料界面行为影响的分子动力学模拟
A. Singh, D. Kumar
The present study investigates the interfacial behavior of functionalized carbon nanotube–polyethylene nanocomposite at different temperatures using molecular dynamics simulations, utilizing the second-generation polymer consistent force field. The carboxylic acid group is used to functionalize the carbon nanotube. In order to calculate interfacial interaction energy and interfacial shear strength of the nanocomposite, various pull-out tests are performed at different temperatures in the range of 1–400 K. The effect of functionalization on the interfacial interaction energy, interfacial shear strength, and glass transition temperature of the nanocomposite are studied in comparison to pristine carbon nanotube–reinforced nanocomposite. Results reveal that for all temperatures and degrees of functionalization, the chirality (i.e. armchair and zigzag) of carbon nanotube has a significant effect on interfacial interaction energy and interfacial shear strength of the nanocomposite. It is also found that functionalizing the carbon nanotube in carbon nanotube–polyethylene nanocomposite enhances its interfacial shear strength at different temperatures. Furthermore, a sudden drop in the value of interfacial interaction energy and interfacial shear strength of the pristine as well as functionalized carbon nanotube–reinforced nanocomposite is observed at a temperature near to its glass transition temperature.
本研究利用第二代聚合物一致力场,通过分子动力学模拟研究了功能化碳纳米管-聚乙烯纳米复合材料在不同温度下的界面行为。羧酸基被用来功能化碳纳米管。为了计算纳米复合材料的界面相互作用能和界面剪切强度,在1 ~ 400 K范围内进行了不同温度下的拉拔试验。研究了功能化对纳米复合材料界面相互作用能、界面剪切强度和玻璃化转变温度的影响,并与原始碳纳米管增强纳米复合材料进行了比较。结果表明,在不同温度和功能化程度下,碳纳米管的手性(扶手椅型和之字形)对复合材料的界面相互作用能和界面剪切强度有显著影响。碳纳米管-聚乙烯纳米复合材料在不同温度下,功能化碳纳米管可以提高其界面剪切强度。此外,在接近其玻璃化转变温度的温度下,原始碳纳米管增强纳米复合材料和功能化碳纳米管增强纳米复合材料的界面相互作用能和界面剪切强度突然下降。
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引用次数: 9
Unsteady three-dimensional stagnation point magnetohydrodynamic flow of bionanofluid with variable properties 变性质生物纳米流体的非定常三维滞止点磁流体动力流动
Md Faisal Md Basir, M. J. Uddin, A. Ismail
Unsteady three-dimensional laminar stagnation point forced convective boundary layer magnetohydrodynamic flow of a bionanofluid with variable transport properties is studied theoretically and numerically. Thermal convective and zero mass flux boundary conditions are incorporated in this study. The transport properties are assumed to be a function of nanoparticle volume fraction to get physically realistic results. The dimensional boundary layer equations along with the coupled boundary conditions are transformed via similarity transformations into a system of ordinary differential equations. The transformed equations are solved numerically using the Runge–Kutta–Fehlberg fourth-, fifth-order numerical method. The effect of selected governing parameters, namely, viscosity, thermal conductive, mass diffusivity, microorganism diffusivity, magnetic field and bioconvection Schmidt number, on the dimensionless velocity, temperature, nanoparticle volume fraction, microorganism, skin friction coefficient, heat transfer rate, mass transfer rate and microorganism transfer rate, is illustrated graphically and interpreted in detail. Comparisons with previous works are carried out for some limiting cases and found to be in good agreement.
对具有变输运性质的生物纳米流体的非定常三维层流驻点强迫对流边界层磁流体动力流动进行了理论和数值研究。本文考虑了热对流和零质量通量边界条件。为了得到物理上真实的结果,我们假设输运性质是纳米颗粒体积分数的函数。将一维边界层方程及其耦合边界条件通过相似变换转化为常微分方程组。利用龙格-库塔-费贝格四、五阶数值方法对变换后的方程进行了数值求解。所选择的控制参数,即粘度、导热系数、质量扩散系数、微生物扩散系数、磁场和生物对流施密特数,对无量纲速度、温度、纳米颗粒体积分数、微生物、皮肤摩擦系数、传热率、传质率和微生物传质率的影响进行了图解和详细解释。在一些极限情况下,与前人的工作进行了比较,发现两者吻合得很好。
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引用次数: 1
Chebyshev collocation computation of magneto-bioconvection nanofluid flow over a wedge with multiple slips and magnetic induction 磁-生物对流纳米流体在多滑移和磁感应楔上流动的切比雪夫配置计算
M. Uddin, M. Kabir, O. Bég, Y. Alginahi
In this article, the steady two-dimensional stagnation point flow of a viscous incompressible electrically conducting bio-nanofluid over a stretching/shrinking wedge in the presence of passively control boundary condition, Stefan blowing and multiple slips is numerically investigated. Magnetic induction is also taken into account. The governing conservation equations are rendered into a system of ordinary differential equations via appropriate similarity transformations. The reduced system is solved using a fast, convergent Chebyshev collocation method. The influence of selected parameters on the dimensionless velocity, induced magnetic field, temperature, nanoparticle volume fraction and density of motile microorganisms as well as on the local skin friction, local Nusselt number, local Sherwood number and density of motile microorganism numbers is discussed and presented graphically. Validation with previously published results is performed and an excellent agreement is found. The study is relevant to electromagnetic manufacturing processes involving bio-nanofluids.
本文研究了在被动控制边界条件、Stefan吹气和多次卡瓦条件下,粘性不可压缩导电生物纳米流体在伸缩/收缩楔形板上的二维稳态滞止点流动。磁感应也被考虑在内。通过适当的相似变换,将控制守恒方程转化为常微分方程组。采用一种快速、收敛的切比雪夫配置法对简化后的系统进行求解。讨论了所选参数对运动微生物的无因次速度、感应磁场、温度、纳米颗粒体积分数和密度以及局部皮肤摩擦、局部努塞尔数、局部舍伍德数和运动微生物数量密度的影响,并给出了图形化的描述。与先前发表的结果进行了验证,发现了非常好的一致性。该研究与涉及生物纳米流体的电磁制造过程有关。
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引用次数: 30
Biomechanical study of magnetohydrodynamic Prandtl nanofluid in a physiological vessel with thermal radiation and chemical reaction 热辐射和化学反应下生理血管中磁流体动力普朗特纳米流体的生物力学研究
K. Ramesh, M. Gnaneswara Reddy, M. Devakar
This article is intended to study the peristaltic motion of a Prandtl nanoliquid through an inclined tapered asymmetric channel. The simultaneous effects such as magnetic field, thermal radiation and chemical reactions have been considered. The geometrical model is considered as tapered asymmetric channel because this situation is observed in the flow of uterine fluid in the uterus. The equations governing the flow are simplified under the assumptions of long wavelength and low Reynolds number. The simplified equations are complex in nature, so that the numerical solutions are presented for the simplified nonlinear partial differential equations considering slip and convective boundary conditions using computational software Mathematica via shooting method. The sundry parameters on the flow quantities have been discussed in detail through graphical and tabular forms. The observed results show that rise in the magnetic effects leads to a reduction in velocity. The radiation parameter decreases the temperature and there is an increment in the pressure gradient with an increase in energy Grashof number. This study is encouraged by exploring the nanofluid dynamics in peristaltic transport as symbolized by heat transport in biological flows, novel pharmacodynamic pumps and gastrointestinal motility enhancement.
本文旨在研究普朗特纳米液体在倾斜锥形非对称通道中的蠕动运动。同时考虑了磁场、热辐射和化学反应等效应。几何模型被认为是锥形不对称通道,因为这种情况是在子宫内子宫液的流动中观察到的。在长波长和低雷诺数的假设下,对流动方程进行了简化。简化后的方程本质上是复杂的,因此利用计算软件Mathematica通过射击法对考虑滑移和对流边界条件的简化非线性偏微分方程进行数值求解。通过图形和表格的形式详细讨论了影响流量的各种参数。观测结果表明,磁效应的增强导致速度的减小。辐射参数使温度降低,压力梯度随能量格拉什夫数的增加而增大。本研究旨在探索以生物流动中的热传递、新型药效学泵和胃肠道运动增强为标志的蠕动运输中的纳米流体动力学。
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引用次数: 9
Production of nanopowders from physical vapor deposited films on nonmetallic substrates by conjunctional freezing-assisted ultrasonic extraction method 联合冷冻辅助超声萃取法制备非金属基板物理气相沉积膜纳米粉体
O. Hammadi
A new technique to extract nanoscale powders from thin films deposited by a physical vapor deposition method on nonmetallic substrates is proposed. Powders were extracted from films of different materials, such as silicon, nickel, copper, iron, aluminum and cobalt, and compounds, such as aluminum nitride, aluminum oxide, copper oxide, iron oxide, nickel cobaltite, nickel ferrite, nickel oxide, silicon carbide, silicon nitride and silicon oxide. These thin films were deposited on glass substrates by magnetron sputtering, pulsed-laser deposition, spray pyrolysis or thermal evaporation, and the particle sizes of the extracted powders were comparable to those of film samples. This technique is fast, low cost, reliable, highly clean and appropriate for large-scale samples.
提出了一种从非金属基底上物理气相沉积的薄膜中提取纳米级粉末的新技术。从不同材料(如硅、镍、铜、铁、铝、钴)和化合物(如氮化铝、氧化铝、氧化铜、氧化铁、钴酸镍、铁酸镍、氧化镍、碳化硅、氮化硅和氧化硅)的薄膜中提取粉末。这些薄膜通过磁控溅射、脉冲激光沉积、喷雾热解或热蒸发等方法沉积在玻璃基底上,提取的粉末粒度与薄膜样品相当。该技术快速、低成本、可靠、高度清洁,适用于大规模样品。
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引用次数: 7
期刊
Proceedings of the Institution of Mechanical Engineers Part N-Journal of Nanomaterials Nanoengineering and Nanosystems
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