Determination of loads applied perpendicularly to the outer boundary of a ring using coefficients of influence

A procedure is explained to determined the amount of several pairs of diametrical loads applied to the outside boundary of a ring when stresses at selected points of the inside or outside boundaries are known. Coefficients of influence are used, following an approach similar to the one presented in a previous paper. Examples of application are given and the possible increase in precision is shown when the number of points of measurements is larger than the number of loads to be determined.     

Mg2Si nanocomposite converted from diatomaceous earth as a potential thermoelectric nanomaterial

With recent literature demonstrating enhancement of the thermoelectric performance of nanoscale materials relative to their corresponding bulk materials, methods to synthesize low-dimensional nanomaterials in large scale at low cost are needed. We demonstrate a method for preparing nanostructured dimagnesium silicide (Mg₂Si) thermoelectric materials that are nanocomposites with MgO by the reduction of diatomaceous earth (diatoms) using a gas-displacement solid state reaction with magnesium vapor. The resulting semiconducting Mg₂Si preserves the general morphology of the original diatoms and their nanosized grains at least down to the size of 30 nm. This reaction represents a possible method for the production of large quantities of low-cost nanoscale thermoelectric materials with potential for enhanced thermoelectric performance.     

Preparation of entangled states of atomic qubits via atom-cavity-laser interaction

<正>We propose a scheme to prepare the Bell states for atomic qubits trapped in separate optical cavities via atom-cavity-laser interaction.The quantum information of each qubit is encoded on the degenerate ground states of the atom,so the entanglement between them is relatively stable against spontaneous emission.The proposed scheme consists of a Mach-Zehnder interferometer(MZI) with two arms,and each arm contains a cavity with an N-type atom in it.It requires two classical fields and a single-photon source. By controlling the sequence and time of atom-cavity-laser interaction,the deterministic production of the atomic Bell states is shown.We also introduce the generalization of the present scheme to generate the 2N-atom Greenberger-Horne-Zeilinger state.     

Parameter estimation in nonlinear age-dependent population dynamics

This paper studies a parameter estimation problem for the Gurtin-MacCamyequation, which is a nonlinear model of age-dependent populationdynamics. In estimating parameters such as the death rate andthe fertility which depend on the age and the total populationfrom a set of fully discrete observations of the population,we use a backward finite-difference scheme. The function-spaceparameter estimation convergence (FSPEC) of this scheme is provedand numerical simulations are performed.