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دسترسی آزاد مقاله
1 - Design and Realization of a Junction-less TFET for Analog and Digital Applications Based on Strain Engineering
Fayzollah Khorramrouze Seyed Ali Sedigh Ziabari Ali HeydariThis paper investigates the effects of the uniaxial tensile strain on the performance of an all silicon junction-less tunneling field-effect transistor (JLTFET) for analog and digital applications. The behavior of the JLTFET under global and local uniaxial strain are st چکیده کاملThis paper investigates the effects of the uniaxial tensile strain on the performance of an all silicon junction-less tunneling field-effect transistor (JLTFET) for analog and digital applications. The behavior of the JLTFET under global and local uniaxial strain are studied based on the energy band diagram at ON, OFF, and ambipolar states. Under local uniaxial tensile strain, it has been observed that the tunneling length at the channel/source interface in the ON state has been decreased and at the channel/drain interface in the OFF state has been increased. Simulations illustrate improvements in ON current, ION/IOFF and steep sub threshold swing (SS) and superior transconductance (gm). The strained JLTFET, also demonstrates capability for low-voltage application and high cut-off frequency (fT) and suppressed ambipolar current (Iamb). پرونده مقاله -
دسترسی آزاد مقاله
2 - Vibration Analysis of Size-Dependent Piezoelectric Nanobeam Under Magneto-Electrical Field
M Ghadiri M Karimi Asl M NorooziThe damping vibration characteristics of magneto-electro-viscoelastic (MEV) nanobeam resting on viscoelastic foundation based on nonlocal strain gradient elasticity theory (NSGT) is studied in this article. For this purpose, by considering the effects of Winkler-Pastern چکیده کاملThe damping vibration characteristics of magneto-electro-viscoelastic (MEV) nanobeam resting on viscoelastic foundation based on nonlocal strain gradient elasticity theory (NSGT) is studied in this article. For this purpose, by considering the effects of Winkler-Pasternak, the viscoelastic medium consists of linear and viscous layers. with respect to the displacement field in accordance with the refined shear deformable beam theory (RSDT) and the Kelvin-Voigt viscoelastic damping model, the governing equations of motion are obtained using Hamilton’s principle based on nonlocal strain gradient theory (NSGT). Using Fourier Series Expansion, The Galerkin’s method adopted to solving differential equations of nanobeam with both of simply supported and clamped boundary conditions. Numerical results are obtained to show the influences of nonlocal parameter, the length scale parameter, slenderness ratio and magneto-electro-mechanical loadings on the vibration behavior of nanobeam for both types of boundary conditions. It is found that by increasing the magnetic potential, the dimensionless frequency can be increased for any value of the damping coefficient and vice versa. Moreover, negative/positive magnetic potential decreases/increases the vibration frequencies of thinner nanobeam. Also, the vibrating frequency decreases and increases with increasing nonlocal parameter and length scale parameter respectively. پرونده مقاله -
دسترسی آزاد مقاله
3 - Size-Dependent Forced Vibration Analysis of Three Nonlocal Strain Gradient Beam Models with Surface Effects Subjected to Moving Harmonic Loads
K Rajabi Sh Hosseini Hashemi A.R NezamabadiThe forced vibration behaviors are examined for nonlocal strain gradient nanobeams with surface effects subjected to a moving harmonic load travelling with a constant velocity in terms of three beam models namely, the Euler-Bernoulli, Timoshenko and modified Timoshenko چکیده کاملThe forced vibration behaviors are examined for nonlocal strain gradient nanobeams with surface effects subjected to a moving harmonic load travelling with a constant velocity in terms of three beam models namely, the Euler-Bernoulli, Timoshenko and modified Timoshenko beam models. The modification for nonlocal strain gradient Timoshenko nanobeams is exerted to the constitutive equations by exclusion of the nonlocality in the shear constitutive relation. Some analytical closed-form solutions for three nonlocal strain gradient beam models with simply supported boundary conditions are derived by using the Galerkin discretization method in conjunction with the Laplace transform method. The effects of the three beam models, the nonlocal and material length scale parameters, the velocity and excitation frequency of the moving harmonic load on the dynamic behaviors of nanobeams are discussed in some detail. Specifically, the critical velocities are examined in some detail. Numerical results have shown that the aforementioned parameters are very important factors for determining the dynamic behavior of the nanobeams accurately. پرونده مقاله -
دسترسی آزاد مقاله
4 - Size-Dependent Vibration Problem of Two Vertically-Aligned Single-Walled Boron Nitride Nanotubes Conveying Fluid in Thermal Environment Via Nonlocal Strain Gradient Shell Model
P Roodgar Saffari M Fakhraie M. A RoudbariThe free vibration behavior of two fluid-conveying vertically-aligned single-walled boron nitride nanotubes are studied in the present paper via the nonlocal strain gradient piezoelectric theory in conjunction with the first-order shear deformation shell assumption in t چکیده کاملThe free vibration behavior of two fluid-conveying vertically-aligned single-walled boron nitride nanotubes are studied in the present paper via the nonlocal strain gradient piezoelectric theory in conjunction with the first-order shear deformation shell assumption in thermal environments. It is supposed that the two adjacent boron nitride nanotubes are coupled with each other in the context of linear deformation by van der Waals interaction according to Lennard–Jones potential function. To achieve a more accurate modeling for low-scale structures, both hardening and softening effects of materials are considered in the nonlocal strain gradient approach. Themotion equations and associated boundary conditions are derived by means of Hamilton’s variational principle, then solved utilizing differential quadrature method. Numerical studies are done to reveal the effect of different boundary conditions, size scale parameters, aspect ratio, inter-tube distance, and temperature change on the variations of dimensionless eigenfrequency and critical flow velocity. پرونده مقاله -
دسترسی آزاد مقاله
5 - بررسی رفتار ارتعاشی غیرخطی نانو ورق دایره ای از جنس مواد هدفمند با استفاده از مدل دیفرانسیلی غیرمحلی گرادیان کرنش
مرتضی پورعبدی محمد شیشه ساز شهرام شهروئی سیدعلیرضا سیدرکنی زادهدر این مقاله، رفتار ارتعاشی غیرخطی یک نانو ورق با هندسه دایره با فرض شرایط مرزی گیردار مورد بررسی قرار گرفته است. برای این منظور، ترکیبی از شکل دیفرانسیلی نظریه الاستیسیته غیرمحلی، مدل گرادیان کرنش و اصل همیلتون، به همراه روابط کرنش-جابجایی غیرخطی فون کارمان و روش باقیم چکیده کاملدر این مقاله، رفتار ارتعاشی غیرخطی یک نانو ورق با هندسه دایره با فرض شرایط مرزی گیردار مورد بررسی قرار گرفته است. برای این منظور، ترکیبی از شکل دیفرانسیلی نظریه الاستیسیته غیرمحلی، مدل گرادیان کرنش و اصل همیلتون، به همراه روابط کرنش-جابجایی غیرخطی فون کارمان و روش باقیمانده وزنی گالرکین برای گسسته سازی معادلات حاکم استفاده شده است. در ادامه تأثیر اثرات اندازه (اثر غیرمحلی و اثر مادی مدل گرادیان کرنش) و شرایط اولیه بر رفتار ارتعاشی سازه مدنظر بررسی شده است. نتایج نشان می دهند که این پارامترهای غیرمحلی و مادی به ترتیب منجر به کاهش و افزایش رفتار فرکانس های غیرخطی شده اند. در نهایت، افزایش مقدار اولیه جابجابی یک روند افزایشی برای نسبت فرکانسی به ازای هر پارامتر غیرمحلی و پارامتر مادی ایجاد میکند. همچنین، برای تمام پارامترهای غیرمحلی و پارامتر ماده، تفاوت بین نسبت فرکانس با افزایش شرایط اولیه کاهش یافته است. پرونده مقاله -
دسترسی آزاد مقاله
6 - آنالیز ارتعاش آزاد نانولولههای ویسکوالاستیک تحت میدان مغناطیسی طولی بر اساس گرادیان کرنش غیرموضعی مدل تیر تیموشنکو
پرویز قزوینیاندر این مقاله ارتعاش آزاد نانولولههای ویسکوالاستیک تحت میدان مغناطیسی طولی مورد بررسی قرار گرفته است. معادله حاکم با استفاده از مدل تیر تیموشنکو و مدل کلوین-ویت بر اساس تئوری گرادیان کرنش غیرموضعی فرمولبندی شده است. در رویه آنالیز از روش تربیع دیفرانسیلی تطبیقی موضعی ( چکیده کاملدر این مقاله ارتعاش آزاد نانولولههای ویسکوالاستیک تحت میدان مغناطیسی طولی مورد بررسی قرار گرفته است. معادله حاکم با استفاده از مدل تیر تیموشنکو و مدل کلوین-ویت بر اساس تئوری گرادیان کرنش غیرموضعی فرمولبندی شده است. در رویه آنالیز از روش تربیع دیفرانسیلی تطبیقی موضعی (LADQM) استفاده شده است. همچنین اثر پارامترهای غیرموضعی، ضریب استهلاک سازهای، پارامتر مقیاس طول ماده و میدان مغناطیسی طولی بر فرکانسهای طبیعی سیستم مورد بررسی قرار گرفته است. ممکن است نتایج این تحقیق برای درک کاربرد بالقوه نانولولهها در سیستم نانو الکترومکانیکی مفید باشد. پرونده مقاله -
دسترسی آزاد مقاله
7 - Relationship between Phenotypic Sexual Characters and Semen Characteristics in Four Strains of Cocks in Northern Nigeria
A.A. Ibrahim N.K. Alade J. Aliyu . A.I MuhammadA study was carried out to evaluate the secondary sexual characteristics of four strains of cocks, comprising of two (2) exotics; Bovan Nera Black (BNB) and Isa Brown (ISB), one (1) improved local strain, Shika Brown (SB) and one (1) unimproved local strain, normal feat چکیده کاملA study was carried out to evaluate the secondary sexual characteristics of four strains of cocks, comprising of two (2) exotics; Bovan Nera Black (BNB) and Isa Brown (ISB), one (1) improved local strain, Shika Brown (SB) and one (1) unimproved local strain, normal feathered cock (NFC). A total of 64 birds (16 for each strain) at 36, 38, 40 and 42 weeks were used for the study. The result indicated that shank length, comb length, comb width, wattle length and wattle width were all significantly (P<0.001) affected by strains, with the exotic strains being superior to the local cocks. Age × strain interactions were also found to be significant. Phenotypic correlations between the secondary sexual characters were found to be significantly high and positive. The correlation between the secondary sexual characters and semen characteristics showed that shank length, wattle length and width, comb length and width had a positive correlation with semen volume (r=0.123, 0.335, 0.195 and 0.408 and 0.348 P<0.01), total sperm count (r=0.202, 0.300, 0.188, 0.403 and 0.320 P<0.05) and normal sperm (r=0.175, 0.143, 0.026, 0.155 and 0.065 P<0.05) respectively. Shank length has a positive correlation with sperm motility (0.010) and dead sperm (0.026), but a negative correlation with live spermatozoa. The result of this study shows a considerable similarity among the strains of cocks with respect to secondary sexual traits. Therefore, it may be inferred from this study that length of shank, comb and wattle are good predictors of semen attributes in male chickens. Selecting cocks with larger shank length, comb and wattle size can improve the semen quality and subsequently, results to higher fertility. پرونده مقاله
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