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Modelling of Surface Roughness in Ultra-High Precision Turning of an RGP Contact Lens Polymer LIMAN Muhammad1, ABOU-EL-HOSSEIN Khaled1,a*, JUMARE Abubakar1, ODEDEYI Peter1 and LUKMAN Abdulqadir1 1Precision Engineering Laboratory, Department of Mechatronics, Nelson Mandela Metropolitan University, Port Elizabeth 6031, South Arica aKhaled.Abou-El-Hossein@nmmu.ac.za Keywords: Surface roughness, Contact lens, Ultra-high precision turning, Prediction model, Cutting parameters, Diamond tool Abstract.
Khatri et al. [4] studied the effect of machining parameters on surface roughness during diamond turning of polycarbonates.
Goel et al. [5] also observed the surface roughness and waviness during machining of polycarbonate.
Fnides et al. [9] used the full factorial design for three cutting factors in developing new model for estimating the surface roughness in turning hardened hot work steel using mixed ceramic tool.

[6] Hassanin A El, Troiano M, Scherillo F, Silvestri AT, Contaldi V, Solimene R, et al.
[7] Hassanin A El, Troiano M, Silvestri AT, Contaldi V, Scherillo F, Solimene R, et al.
[8] Hassanin A El, Velotti C, Scherillo F, Astarita A, Squillace A, Carrino L.
[16] Rubino F, Tucci F, Esperto V, Perna AS, Astarita A, Carlone P, et al.
[25] Duflou JR, Habraken AM, Cao J, Malhotra R, Bambach M, Adams D, et al.

Influence of ECAP on properties high purity Al (99,999%Al) 2.1.
Elongation to failure (El.) is inversing to 0,2% YS.
Table 7 Chemical composition of the investigated alloy Mg Si Mn Fe Cr Zn Cu Al 0.87 0.90 0.85 0.19 0.09 0.03 0.08 bal.
A presence of irregular intermetallic particles of Al(FeMn)Si phase, undissolved Mg2Si particles and fine Mn-rich dispersive particles was observed in the initial state's microstructure.
The role of Mn-rich dispersoids was to prevent the solid solution grains growth of Al-based alloy [15].

(1) (2) where stoichiometric coefficients, x and y, signify the substitution proportion of Sn for Al at the A-site of Ti3(Al,Sn)C2.
SEM micrograph of Ti3(Al,Sn)C2 synthesized from Reaction (1) with x = 0.4.
This means that the extent of Sn substitution for Al to form Ti3(Al,Sn)C2 is narrower for the TiC-adopted sample.
Similar plate-like Ti3(Al,Sn)C2 grains were synthesized from the TiC-adopted sample.
El-Raghy: Metall.

El Hassanin, A.
El Hassanin, F.
El Hassanin, M.
El Hassanin, M.
El Hassanin, C.

This conclusion didn’t agree with the opinion of EL-Jazairi et al [5] and Hansson et al [6].
EL-Jazairi et al thought that nitrite ions didn’t enter into the reaction involved in producing the anode, but reacted with the resulting products of the anode, thus it could not affect the size of the anode [5].
Hansson et al didn’t consider the change of anodic curve resulted from nitrite.
[5] B.EL-Jazairi, N.S.Berke and W.R.Grace.
[6] C.M.Hansson, L.Mammoliti et al.

References [1] Bo, L., et al.
[2] El-Bitar, T., E.
El-Shenawy, and M.
El-Meligy, Development of Ferrite–Bainite Dual Phase (FBDP) High Strength Steel for Automotive Industries.
[9] Aqida, S.N., et al., Thermal fatigue properties of laser treated steels.

., xn) is as follows: Assume that the branch judgment is a simple relationship expression, so all the branches of the judgment are as follows: (3) Wherein El and E2 are two arithmetic expressions, and the θis one of {<, ≤,>, ≥, =, ≠} Simple branch judgment statement El and E2 or a simple Boolean variable El can be transformed into the following equivalent form: f△O Fig. 1 Flow chart of genetic algorithm The value of branch function f is dependent on the branch selection: ①the value of f is positive or 0, when the branch judgment is false; ② f is a negative value or 0, when the branch judgment is true.
[2] Chang Kai, Liao Shih-Sung , Richar d Cha pman, et al.

The middle zone elevates at a level between 1033m and 1034m and.is a saddle area of two mountains, to NW is high terrace of the river Jhelum with ground surface at El. 955~965m, to SE is lower terrace of the river Chikar, a tributary of river Jhelum, with ground surface generally varying between 1020m and 1030m, to NE is a mountain with peak up to El. 1108m and to SW is north slope of the mountain Mir with the highest level of 1170m in the investigated area.
There is a relatively low apparent resistivity zone dipping NE below the ground traces of HFT, having typical angle of 55°~60° at El. 600m.
[5] Shi Yingjun, guo-dong liu et al.

Zhang: Corrosion Inhibitors (Chemical Industry Press, Beijing 2002) In Chinese [3] M.A.Migahed, M.Abd-El-Raouf, A.M, Al-Sabagh, H.M.Abd-El-Bary: Electrochim.
Zeng: Fine Chemical Intermediates Vol. 32 (2002), p. 55 In Chinese [8] M.El Azhar, B.Mernari, M.Traisnel, F.Bentiss, M.Lagrenee: Corros.