Experimental investigation of the response of a harmonically excited hard Duffing oscillator

A single degree-of-freedom torsional vibratory system, which constitutes a third-order dissipative dynamical system, has been fabricated as a mechanical analogue of hard Duffing equation with strong nonlinearity. The forced response of the system reveals complicated and chaotic motion at low frequency regime. Besides usual jump phenomenon, unpredictable jump phenomenon with two and three coexisting periodic attractors is also observed.      

A phosphoranide (10-P-4) anion coordinating to transition metals,as a Lewis base and a π-acceptor

The reaction of 10-P-5 hydridophosphorane 6 with KH provides the 10-P-4 potassium phosphoranide anion 7a . Anion 7a reacts with CpFe(CO)₂I and BrAu(PEt₃) to replace the halide with the phosphoranide as a monodentate ligand forming 8 and 9 . The X-ray structure of 8 shows that the equatorial—Fe(CO)₂Cp ligand of 8 makes the apical P O bonds (1.824 Å) longer than the P O bonds (1.80 Å) of the phosphoranide oxide anion 10 . The P O bonds (1.75 Å) of 6 , with an equatorial proton ligand, are still shorter. This provides evidence that the—Fe(CO)₂Cp ligand is not only a sigma-acceptor Lewis acid ligand, but also a pi-donor that transfers electrons into the O P O three-center bond's anti-bonding orbital to increase its P—O bond lengths. It is a better pi-donor than the  O⁻ pi-donor of phosphoranide oxide 10 .     

A stratified Monte Carlo simulation of CSD in a continuous crystallizer for size-dependent growth

This work deals with the prediction of crystal size distribution (CSD) in a continuous crystallizer for size-dependent growth. Crystal growth rates are described by Abegg, Stevens, and Larson (ASL) model. Stratified Monte Carlo method has been employed to evaluate the integrals involved in the classical moment equation for prediction of CSD. The simulation results have been compared with the available experimental data of K₂CO₃ · 1.5 H₂O crystals in a continuous crystall lizer.     

An approximate theory for the sound radiated from a periodic line-supported plate

An approximate method is presented for estimating the sound power radiated by an infinite plate, supported elastically along parallel, equi-spaced lines and subjected to a simple pressure field convecting uniformly over the plate in a direction perpendicular to the supports. Suitable complex modes are assumed for the induced plate flexural wave motion, and an energy method is used to estimate the plate response and the radiated sound power. The effect on the plate response of the acoustic loading is taken into account. The influence of the convection velocity (which may be subsonic) and of certain plate parameters is investigated.     

Magnetic anomalies in Gd2PdSi3

The results of ac and dc magnetic susceptibility, thermopower and Hall effect measurements of a compound, Gd₂PdSi₃, establish that this compound orders magnetically below T_n = 20 K. Though the ordering appears to be of an antiferromagnetic-type, the paramagnetic Curie temperature is positive with the magnitude being nearly the same as that of T_N, suggestive of the existence of ferromagnetic correlations. The thermopower at 300 K is large, apparently due to Pd 4d electrons, decreasing monotonically with temperature. There is a change in the sign of Hall constant well below T_N Also considering the observation of Kondo-like characteristics above 21K earlier by us, the overall thermal, transport and magnetic behaviour of this compound is interesting.     

Material damping under random excitation

The damping capacity of three materials subjected to narrow-band strain fluctuations is investigated, the material effectively undergoing sinusoidal strain with randomly varying amplitude. For this case, a theoretical relationship is established between the expected value of the energy dissipated per unit volume of the material per period of the narrow-band process and the r.m.s. value of the strain history. This is expressed in terms of material damping constants obtained from harmonic damping measurements. The theoretical relationship is checked against experimental results from narrow-band random experiments on three different materials over low and intermediate stress ranges. Good agreement is found.     

Chiral symmetry breaking parameters from QCD sum rules

We obtain new QCD sum rules by considering vacuum expectation values of two-point functions, taking all the five quark bilinears into account. These sum rules are employed to extract values of different chiral symmetry breaking parameters in QCD theory. We find masses of light quarks, $\text{m}\text{?}\text{=}\text{1}\text{2}\text{(m}{}_{\mathrm{<mtext>u</mtext>}}\text{+m}{}_{\mathrm{<mtext>d</mtext>}}\text{) = 8.4 ± 1.2}\text{MeV}\text{, m}{}_{\mathrm{<mtext>s</mtext>}}\text{= 205 ± 65}\text{MeV}$. Further, we obtain corrections to certain soft pion (kaon) PCAC relations and the violation of SU(3) flavour symmetry by the non-strange and strange quark-antiquark vacuum condensate.     

A survey of simulated annealing as a tool for single and multiobjective optimization

This paper presents a comprehensive review of simulated annealing (SA)-based optimization algorithms. SA-based algorithms solve single and multiobjective optimization problems, where a desired global minimum/maximum is hidden among many local minima/maxima. Three single objective optimization algorithms (SA, SA with tabu search and CSA) and five multiobjective optimization algorithms (SMOSA, UMOSA, PSA, WDMOSA and PDMOSA) based on SA have been presented. The algorithms are briefly discussed and are compared. The key step of SA is probability calculation, which involves building the annealing schedule. Annealing schedule is discussed briefly. Computational results and suggestions to improve the performance of SA-based multiobjective algorithms are presented. Finally, future research in the area of SA is suggested.