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Robust rotation of rotor in a thermally driven nanomotor

View Article: PubMed Central - PubMed

ABSTRACT

In the fabrication of a thermally driven rotary nanomotor with the dimension of a few nanometers, fabrication and control precision may have great influence on rotor’s stability of rotational frequency (SRF). To investigate effects of uncertainty of some major factors including temperature, tube length, axial distance between tubes, diameter of tubes and the inward radial deviation (IRD) of atoms in stators on the frequency’s stability, theoretical analysis integrating with numerical experiments are carried out. From the results obtained via molecular dynamics simulation, some key points are illustrated for future fabrication of the thermal driven rotary nanomotor.

No MeSH data available.


Histories of rotational frequency of rotor, which is driven by the stator with different IRD.(a) e is in [0.15, 0.56]. (b) e is in [0.02, 0.12]. (c) Statistics result of SRF of rotor in [8, 10]ns (e ≥ 0.15) or in [80, 100] ns with respect to e ≤ 0.12.
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f7: Histories of rotational frequency of rotor, which is driven by the stator with different IRD.(a) e is in [0.15, 0.56]. (b) e is in [0.02, 0.12]. (c) Statistics result of SRF of rotor in [8, 10]ns (e ≥ 0.15) or in [80, 100] ns with respect to e ≤ 0.12.

Mentions: Figure 7a and b Show the history of rotational frequency of the rotor driven by the stators with different values of e. As e is within [0.15, 0.54] (Fig. 7a), the rotational frequency of the rotor tends to be stable within 10 ns and the SRF of the rotor is between 159 and 169 GHz. In each case, the average fluctuation of SRF (standard deviation between [8, 10] ns) is less than 1.1 GHz (Fig. 7c). It indicates that the uncertainty of IRD has small influence on the SRF of the rotor as e is within [0.15, 0.54]. When e is larger than 0.54, we find that the rotor rotates unstably. For example, after about 5 ns of rotational acceleration of the rotor, the motor collapses when e = 0.55 whereas the motor collapses after ~6.4 ns when e = 0.56. According to the discussion on temperature and relative positions between rotor and stators, the collapse can be avoided if, we, for example, reduce the temperature or increase the value of a. It also implies that the rotor may have a larger value of SRF when e > 0.54 as the collapse of system can be avoid. Hence, the uncertainty of e has piece-wise effect on SRF of the rotor. This is also verified by the data shown in Fig. 7b, i.e., where e is less than 0.12. Due to the smaller value of e, the rotational frequency of the rotor is also lower. Especially, when e is less than 0.07, the SRF of the rotor is less than 30 GHz and the fluctuation of rotational frequency is also much higher than that when e is larger than 0.15. Therefore, controlling the SRF of the rotor by adjusting the value of e is theoretically feasible but infeasible in practice due to the piece-wise effect.


Robust rotation of rotor in a thermally driven nanomotor
Histories of rotational frequency of rotor, which is driven by the stator with different IRD.(a) e is in [0.15, 0.56]. (b) e is in [0.02, 0.12]. (c) Statistics result of SRF of rotor in [8, 10]ns (e ≥ 0.15) or in [80, 100] ns with respect to e ≤ 0.12.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5385497&req=5

f7: Histories of rotational frequency of rotor, which is driven by the stator with different IRD.(a) e is in [0.15, 0.56]. (b) e is in [0.02, 0.12]. (c) Statistics result of SRF of rotor in [8, 10]ns (e ≥ 0.15) or in [80, 100] ns with respect to e ≤ 0.12.
Mentions: Figure 7a and b Show the history of rotational frequency of the rotor driven by the stators with different values of e. As e is within [0.15, 0.54] (Fig. 7a), the rotational frequency of the rotor tends to be stable within 10 ns and the SRF of the rotor is between 159 and 169 GHz. In each case, the average fluctuation of SRF (standard deviation between [8, 10] ns) is less than 1.1 GHz (Fig. 7c). It indicates that the uncertainty of IRD has small influence on the SRF of the rotor as e is within [0.15, 0.54]. When e is larger than 0.54, we find that the rotor rotates unstably. For example, after about 5 ns of rotational acceleration of the rotor, the motor collapses when e = 0.55 whereas the motor collapses after ~6.4 ns when e = 0.56. According to the discussion on temperature and relative positions between rotor and stators, the collapse can be avoided if, we, for example, reduce the temperature or increase the value of a. It also implies that the rotor may have a larger value of SRF when e > 0.54 as the collapse of system can be avoid. Hence, the uncertainty of e has piece-wise effect on SRF of the rotor. This is also verified by the data shown in Fig. 7b, i.e., where e is less than 0.12. Due to the smaller value of e, the rotational frequency of the rotor is also lower. Especially, when e is less than 0.07, the SRF of the rotor is less than 30 GHz and the fluctuation of rotational frequency is also much higher than that when e is larger than 0.15. Therefore, controlling the SRF of the rotor by adjusting the value of e is theoretically feasible but infeasible in practice due to the piece-wise effect.

View Article: PubMed Central - PubMed

ABSTRACT

In the fabrication of a thermally driven rotary nanomotor with the dimension of a few nanometers, fabrication and control precision may have great influence on rotor’s stability of rotational frequency (SRF). To investigate effects of uncertainty of some major factors including temperature, tube length, axial distance between tubes, diameter of tubes and the inward radial deviation (IRD) of atoms in stators on the frequency’s stability, theoretical analysis integrating with numerical experiments are carried out. From the results obtained via molecular dynamics simulation, some key points are illustrated for future fabrication of the thermal driven rotary nanomotor.

No MeSH data available.