A Heuristic Approach to Quadratic Assignment Problem

A new algorithm for solving quadratic assignment problems is presented. The algorithm, which employs a sequential search technique, constructs a matrix of lower bounds on the costs of locating facilities at different sites. It then improves the elements of this matrix, one by one, by solving a succession of linear assignment problems. After all the elements of the matrix are improved, a feasible assignment is obtained, which results in an improved value for the objective function of the quadratic assignment problem. The procedure is repeated until the desired accuracy in the objective function value is obtained.     

Synthesis of phosphonato esters involving heterocyclic biological bases in a highly diastereoselective and chemoselective route

Abstract  

Synthesis of five phosphonato esters has been accomplished via reaction between dimethyl acetylenedicarboxylate and triphenyl phosphite in the presence of biological compounds such as theophylline, 4-hydroxypyrimidine, 2H-3,1-benzoxazine-2,4(1H)-dione, 2-chloroaniline, or 3-nitroaniline at ambient temperature. The configuration of the compounds was determined on the basis of coupling constants emerging from the Karplus equation.     

Synthesis of 3-aminoisoxazolmethylnaphthols via one-pot three-component reaction under solvent-free conditions

A one-pot three-component condensation reaction of 3-amino-5-methylisoxazole, aryl aldehyde and 2-naphthol to afford the corresponding 3-amino isoxazolmethylnaphthols in good to excellent yields. The remarkable features of this new procedure are high conversions, clean reaction condition, short reaction time, nonhazardous and environmentally friendly reaction condition, inexpensive and easily commercially availability of the catalyst and simple work-up procedures.     

A simple plasticity model for prediction of non-coaxial flow of sand

A bounding surface plasticity model for non-coaxiality, another aspect of anisotropic behavior of sands under rotation of principal stress axes; is developed in the critical state framework. Numerous experimental evidences exist that corroborate dependence of plastic shear strain rate direction on inherent fabric anisotropy. At first, general expressions for plastic strain rate with respect to possible emerge of non-coaxial flow are obtained. Consequently, using an anisotropy state parameter that is specially developed for this model and accounts for the interaction between imposed loading and soil fabric; effect of anisotropy on plastic flow direction is taken into account. Besides, novel circumstances are proposed for plastic modulus and dilatancy under rotation of principal stress axes. Finally, it is shown that the model is able to simulate successfully the non-coaxial behavior of sands subjected to principal stress axes rotation.     

A Quick and Clean Procedure for Synthesis of α‐Aminophosphonates in Aqueous Media

A green and efficient procedure for the synthesis of α‐aminophosphonates has been developed in water as a green and nonhazardous solvent, from condensation between aromatic aldehydes, aniline, and triphenyl phosphite at 80°C. This methodology has a number of advantages including clean reaction conditions, easy work‐up, and environmentally friendly.     

Linear frequency modulation photoacoustic radar: optimal bandwidth and signal-to-noise ratio for frequency-domain imaging of turbid media

The development of the pulse compression photoacoustic (PA) radar using linear frequency modulation (LFM) demonstrated experimentally that spectral matching of the signal to the ultrasonic transducer bandwidth does not necessarily produce the best PA signal-to-noise ratio, and it was shown that the optical and acoustic properties of the absorber will modify the optimal bandwidth. The effects of these factors are investigated in frequency-domain (FD) PA imaging by employing one-dimensional and axisymmetric models of the PA effect, and a Krimholtz-Leedom-Matthaei model for the employed transducers. LFM chirps with various bandwidths were utilized and transducer sensitivity was measured to ensure the accuracy of the model. The theory was compared with experimental results and it was shown that the PA effect can act as a low-pass filter in the signal generation. Furthermore, with the PA radar, the low-frequency behavior of two-dimensional wave generation can appear as a false peak in the cross correlation signal trace. These effects are important in optimizing controllable features of the FD-PA method to improve image quality.     

Vibrations of segmented shells

An analytical and experimental investigation was performed to determine the natural frequencies and mode shapes of a cone-cylinder segmented shell. The finite-element technique was used to predict the natural frequencies and mode shapes of a clamped segmented shell. In the experimental phase of the program, the shell was excited by an electromagnet and the natural frequencies were determined with the aid of a microphone. Holographic interferometry was used to identify the mode shapes for each resonant frequency. The analytical and experimental results were in good agreement with one another.     

Preparation of thiazolidin-4-one derivatives using ZnO–NiO–NiFe2O4 nano-composite system

The hydrothermal synthesis of ZnO–NiO–NiFe₂O₄ nano-composite is reported. The sample was utilized to characterize via XRD, FE-SEM, EDS, FT-IR, UV–Vis, and BET techniques. The sample consisted of three different phases as ZnO (hexagonal), NiO (cubic), and NiFe₂O₄ (cubic) with the average particle size as 34 nm and specific surface area, average pore diameter, and pore volume as 64.35 m² g^?1, 13.02 nm, and 0.201 cm³ g^?1, respectively. Catalytic behavior of the nano-composite was investigated on the synthesis of thiazolidin-4-one derivatives under thermal and ultrasonic irradiation condition. Our results show that the catalytic activity of ZnO–NiO–NiFe₂O₄ nano-composite is much higher than ZnO, NiO, and NiFe₂O₄ metal oxides. All products were prepared in high yields with short reaction times. In addition, the catalyst was recovered for at least five times.

     

Synthesis and Crystal Structure Study of Diethyl Aryl(benzo[d]thiazol‐2‐ylamino)methyl Phosphonates

A three‐component synthesis of α‐aminophosphonate is described from a reaction between aldehydes, 2‐aminobenzothiazole, and triethyl phosphite in the presence of InCl₃ as a catalyst under solvent‐free conditions for the generation of the particular α‐aminophosphonates. These products have two potentially biologically active parts, aminophosphonate and benzothiazole. This method offers advantages such as short reaction times, good yields, solvent‐free conditions, and easy workup with the green aspects by avoiding toxic catalysts and solvents. The crystal structure of 4b has been determined by X‐ray crystallography. This compound crystallizes in the monoclinic space group C2/c with cell parameters a = 21.9285(5) Å, b = 10.3221(2) Å, c = 18.5979(5) Å, β = 108.759(3)°, V = 3985.99(18) ų, D_calc = 1.301 mg m⁻³, and Z = 8. The final R value is 0.0501 for 3741 reflections. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 24:58–65, 2013; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21063     

Power-law regularities in human language

Complex structure of human language enables us to exchange very complicated information. This communication system obeys some common nonlinear statistical regularities. We investigate four important long-range features of human language. We perform our calculations for adopted works of seven famous litterateurs. Zipf’s law and Heaps’ law, which imply well-known power-law behaviors, are established in human language, showing a qualitative inverse relation with each other. Furthermore, the informational content associated with the words ordering, is measured by using an entropic metric. We also calculate fractal dimension of words in the text by using box counting method. The fractal dimension of each word, that is a positive value less than or equal to one, exhibits its spatial distribution in the text. Generally, we can claim that the Human language follows the mentioned power-law regularities. Power-law relations imply the existence of long-range correlations between the word types, to convey an especial idea.