A number of mono(carboxylato )mono(a lkoxo)nicke l ( I I ) complexes of the general formula, N i ( O R ) ( O O C R ' ) , (with R ' = C13H07, C15H31 and C17H35) have been synthesized (where R = Me and Pr») b y the reactions o f nickel methoxide and isopropoxide with the respective carboxyl ic acids in equimolar ratio and (where R = E t and Bu<) by alcohol interchange reactions. A study of the mo...

We present a theoretical study of various definitions of laser beam width in a given cross section. Quality of the beam is characterized by dimensionless beam propagation products (BPPs) Δx·Δθ(x)/λ, which are different for the 21 definitions presented, but are close to 1. Six particular beams are studied in detail. In the process, we had to review the properties for the Fourier transform of var...

We introduce a new family of (2+1)D light beams with pre-engineered abruptly autofocusing properties. These beams have a circularly symmetric input profile that develops outward of a dark disk and oscillates radially as a sublinear-chirp signal, creating a series of concentric intensity rings with gradually decreasing width. The light rays involved in this process form a caustic surface of revo...

We study the diffraction of Gaussian pulses and beams within the framework of boundary diffraction wave theory. For the first time the boundary diffraction wave theory is applied to pulsed Gaussian beams, and it is shown that the diffracted field of a pulsed Gaussian beam on a circularly symmetric aperture can be evaluated by a single 1D integration along the diffracting aperture at every point...

In the TESLA linear collider, two interaction regions are foreseen, one for ee collisions at zero crossing-angle, and the other one for ee , e e or collisions at about 40 mrad crossing angle. Beam switchyards must therefore be designed after the electron and positron(or electron) linacs to switch the electron and positron (or electron) beams and serve the two interaction regions. On the electro...

In this paper, we study the progressive collapse of three-dimensional framed structures made of reinforced concrete after the sudden loss of a column. The structures are represented by elastoplastic Euler-Bernoulli beams with elongation-rotation failure threshold. We performed simulations using the discrete element method considering inelastic collisions between the structural elements. The res...

Many explanations of halo formation in high current ion beams require the existence of particles which are outside the beams central core. We propose a mechanism which is capable of moving some particles outside the core. Specifically, we consider a 2-D KV beam which is started into a uniform density breathing oscillation by some mismatch in the transverse focusing pattern. We then consider per...

We have chosen an Ising ASYNNNI (ASYmmetric Next Nearest Neighbor Interaction)   model under a grand canonical regime to investigate structural phase transition from a high symmetric tetragonal (Tet) to a low symmetric orthorhombic in YBa2Cu3O6+x , 0<x<1,  HTc system. Ordering process for absorbed oxygens from an external gas bath into the basal plane of the layered system is studied by Monte C...

Introduction: The main advantage of using ion beams over photons in radiotherapy is due to their inverse depth-dose profiles, allowing higher doses to tumors, while better sparing normal tissues. When calculating dose distributions with ion beams, one crucial point is the uncertainty of the Bragg-peak range. Recently great effort is devoted to enhance the accuracy of the comput...

The novelty of the present work is to study simultaneous influence porosities and partial Pasternak foundation support on dynamics functionally graded (FG) beams carrying a moving load. are made from an open-cell steel foam with symmetric asymmetric porosity distributions in thickness direction. Based refined third-order shear deformation theory, two-node beam element ten degrees freedom derive...