Indian Journal of Engineering & Materials Sciences

Engineering
Vibrating structure piezoelectric hollow cylinder gyroscope	7
A K Singh [IPC Code: Int. Cl.⁷ G01C 19/00]

Silica-on-silicon based 1×N optical splitter: Design, fabrication and characterization	12
Aji Baby, C Dhanavantri, J P Pachauri, S Johri, Pawan Kumar & B.R Singh [IPC Code: Int. Cl.⁷ H01R 31/02]

Effects of erbium-doping depth in cladding on the performance of dispersion compensating optical fibre amplifier	17
Pramod R Watekar, M L N Goswami, J C Biswas & H N Acharya [IPC Code: Int. Cl.⁷ H01S, C03B 37/00]

Some aspects on barrelling in solid billets of non-circular aluminium during cold upset forging with different lubricants	24
K.Manisekar & R.Narayanasamy [IPC Code: Int. Cl.⁷ B21J 13/10]

Influence of chain topology on function and path generation	33
A Srinath & A C Rao [IPC Code: Int. Cl.⁷ G09B]

Modeling of gas-solid reactions for ellipsoidal particles	37
S Saha, S K Basu, S DasGupta & S De [IPC Code: Int. Cl.⁷ B01J 8/00]

Comparative analysis of using artificial neural networks (ANN) and gene expression programming (GEP) in backcalculation of pavement layer thickness	42
Mehmet Saltan& Serdal Terzi [IPC Code: Int. Cl.⁷ E01C 9/10]

Unsteady laminar flow of visco-elastic fluid of second order type between two parallel plates	51
Ch V Ramana Murthy & S B Kulkarni [IPC Code: Int. Cl.⁷ F15D]

Materials Science

Spectroscopic and thermal studies of zinc/cadmium halide doped silver phosphate glasses	58
S S Das, B P Baranwal, C P Gupta & Punita Singh [IPC Code: Int. Cl.⁷ C03C 3/00]

Absorption studies of tripositive praseodymium and neodymium doped zinc fluoride borophosphate (ZFBP) glasses	65
Y K Sharma, R P Dubedi, V Joshi, K B Karnataka& S S L Surana [IPC Code: Int. Cl.⁷ C03C 3/00]
Theoretical studies of an axisymmetric compound flow problem of sintered preform	75
R K Ranjan & S Kumar [IPC Code: Int. Cl.⁷ B22F 1/00]

IPC: International Patent Classification
Int. Cl.⁷: International Classification 7^th edition, 1999

Vibrating structure piezoelectric hollow cylinder gyroscope

This paper presents the development of piezoelectric vibrating structure gyroscope. The vibrating structure used here is made of piezoelectric PZT-5J and cylindrical in shape. It has eight equally spaced positive electrodes on the outer side and one common negative electrode on the inner side. Two of the positive electrodes are used for excitation of the structure and two for detection. The excitation of structure is done at its resonance frequency providing maximum sensitivity. The performance of the developed piezoelectric gyroscope is tested with a microprocessor controlled turntable. Signal conditioning with automatic gain control (AGC) and results, for clockwise and anti-clockwise rotations for different rotation speeds, are discussed in the paper.

Silica-on-silicon based 1´N optical splitter: Design, fabrication and characterization

The present paper deals with the design, fabrication technology and performance of silica-on-silicon based 1´4 and 1´8 optical power splitter. The basic waveguide structure with S-bends and Y-junctions have been used for the splitter design using BPM software. The optimized process parameters related to choice of metal masking layer, chemistry used for deep dry etching of core layer, dependence of etch process parameters on anisotropy and sidewall smoothness, dicing and fibre alignment are presented. An indigenously built ECR/RIE system especially for deep dry etching of silica layer is also described. The results on splitting insertion loss and uniformity maximum across the channel measured on 1´4 and 1´8 splitters are presented.

Effects of erbium-doping depth in cladding on the performance of dispersion compensating optical fibre amplifier

The theoretical studies regarding change of the erbium-doping depth in cladding from the surface of the core on the performance of the erbium-doped dispersion compensating optical fibre (EDDCF) have been reported. We have also calculated the limits of the detune factor for which the performance of the detuned-EDDCF can be brought equivalent to the performance that would have been obtained with the designed value. This study is useful for deciding the limits of the doping-depth during fabrication of the EDDCF.

Some aspects on barrelling in solid billets of non-circular aluminium

during cold upset forging with different lubricants

Experiments were carried out to generate data on the cold upset forging of square and rectangular billets of annealed aluminum with different lubricants. The measured radius of curvature of the barrel was found to confirm with the calculated value. The calculations were made on the assumption that the curvature of the barrel followed the geometry of circular arc. It was further found that the measured radius of curvature of the barrel exhibited a straight-line relationship against the new geometrical shape factor irrespective of the shape of the non-circular solid billets. Further, empirical relations were found to exist between the measured radius of curvature of the barrel with other variables like hydrostatic stress and stress ratio parameter.

Influence of chain topology on function and path generation

A number of distinct kinematic chains are available with the same number of links and degree-of-freedom (dof). They may differ, from one another, in respect of link assortment and the structure both of which are expected to influence the anticipated performance of the chains. This paper presents a method to compare various chains from the structural error point of view. In other words, an attempt is made to bridge the gap between dimensional and structural synthesis.

Modeling of gas-solid reactions for ellipsoidal particles

Gas-solid reaction rates for an ellipsoidal particle have been derived in this paper. The shrinking core model has been considered for this purpose. The progress of the reaction front with time for different controlling regimes, namely, gas film resistance controlled, diffusion in the ash layer controlled and chemical reaction controlled have been dealt with, separately.

Comparative analysis of using artificial neural networks (ANN) and gene expression programming (GEP) in backcalculation of pavement layer thickness

Pavement deflection data are often used to evaluate a pavement’s structural condition non-destructively. It is essential not only to evaluate the structural integrity of an existing pavement but also to have accurate information on pavement surface condition in order to establish a reasonable pavement rehabilitation design system. Pavement layers are characterized by their elastic moduli estimated from surface deflections through backcalculation. Backcalculating the pavement layer moduli is a well-accepted procedure for the evaluation of the structural capacity of pavements. The ultimate aim of the backcalculation process from non-destructive testing (NDT) results is to estimate the pavement material properties. Using backcalculation analysis, flexible pavement layer thicknesses together with in-situ material properties can be backcalculated from the measured field data through appropriate analysis techniques. In this study, artificial neural networks (ANN) and gene expression programming (GEP) are used in backcalculating the pavement layer thickness from deflections measured on the surface of the flexible pavements. Experimental deflection data groups from NDT are used to show the capability of the ANN and GEP approaches in backcalculating the pavement layer thickness and compared each other. These approaches can be easily and realistically performed to solve the optimization problems which do not have a formulation or function about the solution.

Unsteady laminar flow of visco-elastic fluid of second order type between two parallel plates

In this paper a general solution of the unsteady state laminar flow of a visco-elastic fluid of second order type between two parallel plates has been obtained, under usual assumption of no-slip condition at the boundary. The solution is obtained not by using any of the regular methods, but by employing the concepts of Duhamel's theorem. The velocity profiles are found to be more steep and further, as time passes through, the profiles are significantly distributed. Further, as time elapses, the skin friction on the plates also increases. The applications are many and are of interest, as it approximates to the flows that are commonly encountered in technological and engineering practices.

Spectroscopic and thermal studies of zinc/cadmium halide doped
silver phosphate glasses

A number of samples of silver phosphate glasses doped with 1%, 5%, 10% and 20% zinc and cadmium halides were prepared. Control samples of undoped silver phosphate glasses were also prepared. These glasses were characterized by X-ray diffraction, IR spectra, ion transport, and DSC studies. The T_g values obtained from DSC curves were found to increase with increasing concentration of the dopants (Zn/CdX₂) where X= Cl, Br, I in all the cases. The T_g and the conductivity values of all the samples of silver phosphate glasses show the following trend: T_g ( CdX₂) > T_g ( ZnX₂); X = Cl or Br or I; T_g ( MCl₂) > T_g ( MBr₂) > T_g ( MI₂); M = Cd or Zn; s ( MI₂) > s ( MBr₂) > s ( MCl₂); M = Cd or Zn. These results have been discussed and explained on the basis of changes in the structure of the glass matrix by the addition of the halide ions of different sizes, IR spectra and ion transport studies.

Absorption studies of tripositive praseodymium and neodymium doped zinc fluoride borophosphate (ZFBP) glasses

Zinc fluoride borophosphate (ZFBP) glasses doped with tripositive praseodymium and neodymium ions have been prepared by melt quenching technique. The final composition of glasses in mol.% is 15.44 B₂O₃ – 39.77 P₂O₅ -17.36 Na₂O – 16.67 Al₂O₃ – 10.74 ZnF₂ – R Ln (where R= 0.0, 0.1, 0.3 and 0.5 mol % and Ln = Pr³⁺ and Nd³⁺). The absorption spectra of doped ZFBP glasses have been recorded at room temperature. Eight absorption bands have been observed from the ground state ³H₄ to excited states ³F_2,³F_3,³F_4,¹G_4, ¹D₂, ³P₀, ³P₁ and ³P₂ in Pr³⁺ doped ZFBP glasses and twelve absorption bands from the ground state ⁴I_9/2 to excited states ⁴F_3/2, ⁴F_5/2, ⁴F_7/2, ⁴S_3/2, ⁴F_9/2, ²H_11/2, ⁴G_5/2, ⁴G_7/2, ⁴G_9/2, ²G_9/2, ⁴G_11/2, and ²P_1/2 in the case of Nd³⁺ doped ZFBP glasses. From these spectral data various energy interaction parameters like Slater-Condon parameter F_k (k=2, 4, 6), Lande´ parameter z_4f and Racah parameters E^k (k=1,2,3) have been computed. Nephelauxetic ratio (b¢) and bonding parameters (b^1/2) have also been computed from these parameters to study the nature of bonding in doped glasses. The intensities of the f-f transitions in the absorption spectra have been analyzed by the application of the Judd-Ofelt theory. J-O parameters (W_l) have been computed. W_l parameters of ZFBP glasses have been compared with those of similar glasses to infer the nature of bonding in these glasses.

Theoretical studies of an axisymmetric compound flow problem of sintered preform

The paper reports a theoretical investigation into the various aspects of an axisymmetric sintered compound flow problem of powder preforms which have been compacted and sintered from atomized metal powder. Many forging processes involve flow of preform in more than one direction. Die and process design require to determine the flow behaviour and the forging force. The analysis of a general axisymmetric problem is discussed and presented graphically here. In addition to the fundamental interest, it emphasizes the power of upper-bound analysis when applied to the prediction of compound sintered metal flow.