Development of a tyre traction testing facility

An experimental setup comprising up of an indoor soil bin, a single wheel tester (SWT), a soil processing trolley, a drawbar pull loading device and an instrumentation unit was developed to perform traction tests in the soil bin to study the effect of soil, tyre and system parameters on the performance of tyres. The design of the single wheel tester was such that the dynamic weight reaction force is equal to that measured statically. It is a simple wheeled device, capable of testing tyres of up to 1.5 m in diameter, vertical force up to 19 kN, net pull up to 7.2 kN, torque up to 5.5 kN m, and speed up to 3.5 km/h.     

Dynamics of short fiber suspensions in bounded shear flow

We have studied the dynamics of non-colloidal short fiber suspensions in bounded shear flow using the Stokesian dynamics simulation. Such particles make up the microstructure of many suspensions for which the macroscopic dynamics are not well understood. The effect of wall on the fiber dynamics is the main focus of this work. For a single fiber undergoing simple shear flow between plane parallel walls the period of rotation was compared with the Jeffrey’s orbit. A fiber placed close to the wall shows significant deviation from Jeffrey’s orbit. The fiber moving near a solid wall in bounded shear flow follows a pole-vaulting motion, and its centroid location from the wall is also periodic. Simulations were also carried out to study the effect of fiber–fiber interactions on the viscosity of concentrated suspensions.     

Spin density distributions in radical anions of heterocyclic amine N-oxides

The unrestricted Hartree-Fock (UHF) method of Snyder and Amos is used to calculate, in the -electron approximation, the spin density distributions in radical anions of heterocyclic amine N-oxides. The computed spin densities are observed to be in good agreement with the experimental values. The computed spin density distribution of the radical anion of pyridine N-oxide is consistent with the greater susceptibility of pyridine N-oxide relative to pyridine to electrophilic nitration. Also, the calculations are consistent with the lower basicity of the N-oxides relative to the parent bases.     

Pseudohalide derivatives of (η -cyclopentadienyl-η-methylcyclopentadienyl) titanium (IV)

Summary Pseudohalide complexes of the (-cpL)TiXZ type (where cp = cyclopentadienyl, L = -McCs₅-H₄ and X = N3, NCS, NCO or NCSe) have been prepared in aqueous and nonaqueous media and characterized by elemental analyses, i.r. and n.m.r. spectroscopy. I.r. spectroscopy shows that NCS, NCO and NCSe are bonded to the titanium atom through nitrogen in these complexes which are thus true isothiocyanato, isocyanato and isoselenocyanato derivatives respectively.     

Kinetic study of the oxidation of isobutyraldehyde by aqueous chlorine

The kinetics of oxidation of isobutyraldehyde with aqueous chlorine has been investigated in 11.6 vol. % aqueous acetic acid. The reaction is first order with respect to both substrate and chlorine. Molecular chlorine is the principal oxidant. The influence of various factors, e.g. ionic strength, inorganic salts, D₂O and temperature on the initial rate has been studied. The activation parameters have been calculated and a possible mechanism is suggested.

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11,6% . , . . ( , , D₂O) . .

     

Preparation and characterization of some stereochemically rigid seven-coordinate η-cyclopentadienyltris(N,N-dialkyldithiocarbamato)hafnium(IV) complexes

Summary N,N-Dialkyldithiocarbametohafnium(IV) complexes of the type -CpHf(S₂CNR₂)₃, (R = Me or Et) have been prepared in nonaqueous media by reacting dichlorodicyclopentadienylhafnium(IV) with sodium salts of substituted dithiocarbamic acids. Conductance and i.r. studies show that these complexes are nonelectrolytes in which all of the dithiocarbamate ligands are bidentate. A coordination number of seven may be assigned to hafnium(IV) in these complexes, 'H n.m.r. spectra of the complexes in CDCI₃ at ambient temperature (30°) indicate that the metal centered rearrangement and the S₂C N bond rotation are both slow on the n.m.r. time scale. A capped octahedron configuration is suggested for these complexes.Author to whore all correspondence should be addressed.     

Ionospheric total electron content and slab-thickness at low latitudes in Indian zone

Observations of Faraday rotation of beacon signals from low orbiting satellite BE-B recorded at one station near the dip equator (Kodaikanal, dip 3·4° N) and at another station near the peak of the equatorial anomaly (Ahmedabad, dip 34° N) give a complete coverage of the equatorial anomaly belt in Indian zone. Contours of total elctron content (TEC) are obtained on a grid of latitudeversus local time for the different seasons of low (1964–66) and high (1967–69) solar activity epochs in the latitude belt 10° S to 26° N dip latitude. The development of the equatorial anomaly and its dependence on season and solar activity are discussed. Using similar contours of F₂ layer critical frequency, f₀F₂ contours of equivalent slab-thickness, τ are also constructed. The dependence of τ on season and solar activity and its implications on temperature are discussed.     

Effective interactions and the 1f72 sub-shell closure in the 2p-1f shell

It is estimated that the ground state of ⁵⁶Ni as given by the Kuo-Brown effective interaction modified to satisfy the restrictions imposed by the BE2 systematics contains about 13 particles in the $\text{1f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ shell.