Free vibration analysis of a steel T-Shape frame including semi-rigid Khorjini connection with continuous beam

This article deals with the free vibration analysis and determination of seismic parameters of a T-Shape frame which consists of a continuous beam and a column connected to each other by means of a semi-rigid Khorjini connection. The individual members of the frame are assumed to be governed by the transverse vibration theory of an Euler-Bernoulli beam and the semi-rigid Khorjini connection is modeled employing a rotational spring. First of all, a closed-form solution is proposed and then, a numerical analysis is performed for some comparison and validation purposes. The closed-form solution is developed by solving the frame equations of motion, directly. For this reason, some mathematical techniques such as Fourier transform and the well-known complementary solutions are utilized. In this process, some differential equations must be solved, and several boundary conditions should be satisfied. Afterward, the free vibration parameters of the frame are attained. These parameters are also obtained using finite element method as a numerical analysis and it is observed that the results obtained by this approach are completely coincident with the result of closed-form solution. Also, seismic parameters of the frame and seismic behavior of the semi-rigid Khorjini connection for different cases are investigated and their results are compared. Finally, two special cases are presented and, furthermore, the connection mass effect on system frequency is investigated.     

Design of a new scheme to indicate the domain of applicability of near singular approach in 2D BEM

The Gauss–Legendre integration is not appropriate for singular and nearly singular integrations in BEM. In this study, some criteria are introduced for recognizing the nearly singular integrals in integral form of Laplace equation. At first, a criterion is obtained for constant element and consequently higher order elements are investigated. To indicate this near singular approach, there are different formulations amongst which the Romberg method was selected due to its compatibility with analytical integration. The singular integrals were carried out by composing the Romberg method and midpoint rule. The potential functions over geometrically linear BEM elements can be defined in the form of constant, linear or other types of interpolation functions. In those elements, the Gauss–Legendre integration will be accurate, if the source point is placed out of the circle with a diameter equal to element length and its center matched to midpoint of the element. Also, some criteria are obtained for parabolic function of geometry over an element.     

Carbon nanohorn-based nanofluids: characterization of the spectral scattering albedo

The full characterization of the optical properties of nanofluids consisting of single-wall carbon nanohorns of different morphologies in aqueous suspensions is carried out using a novel spectrophotometric technique. Information on the nanofluid scattering and absorption spectral characteristics is obtained by analyzing the data within the single scattering theory and validating the method by comparison with previous monochromatic measurements performed with a different technique. The high absorption coefficient measured joint to the very low scattering albedo opens promising application perspectives for single-wall carbon nanohorn-based fluid or solid suspensions. The proposed approximate approach can be extended also to other low-scattering turbid media.     

Merit Figures for the Optical Design of CSP Plants

This work proposes some optical merit figures useful for solar concentration in the phase of optical design. The examined systems are CSP （concentrated solar power） plants with heliostats fields. In order to characterize them, it is suggested to use some optical merit figures, applicable to every CSP plant and synthetize its optical performance. The proposed merit figures have the aim of assessing mirrors field efficiency and receiver optical efficiency. In particular, they are identified using a new definition of the input flux on the mirrors field. The practical advantage of using the optical merit figures is illustrated by means of a simulation.     

Frequency- and intensity-noise measurements of a widely tunable 2-/spl mu/m Tm-Ho:KYF laser

The measurement of the frequency and intensity noise in a novel single-mode 2-/spl mu/m Tm-Ho:KYF laser is presented. The laser frequency noise is measured by exploiting the fringe side of the transmission of a Fabry-Pe/spl acute/rot interferometer. The measured power spectral density of the frequency noise is principally characterized by a random-walk noise contribution, which sets an emission linewidth of /spl sim/ 600 kHz for the 2-/spl mu/m radiation. The relative intensity noise (RIN) reaches the quantum limit of -155 dB/Hz for Fourier frequencies above 1 MHz and shows a maximum level of -90 dB/Hz at the relaxation-oscillation frequency of 20 kHz.     

Real-time game-theoretic model predictive control for differential game of target defense

This paper evaluates experimentally a novel strategy for solving a variant of the differential game of target defense in presence of obstacles. The game is widely applied in the areas of military defense for protecting important equipment such as a ship, an aircraft, a moving vehicle, or a sensitive installation from a malicious attacker. The state-of-the-art approaches mostly employ an offline optimization strategy that is only applicable to holonomic robots. Moreover, most of the approaches could not autonomously avoid obstacles or take into account uncertainties. As a consequence, this paper presents an online optimization technique, by designing a trade-off parameter that integrates game theory with the model predictive control, which allows a nonholonomic defender to intercept the attacker while simultaneously defending the target. Simulations under different conditions as well as several indoor laboratory experiments validate the proposed approach. Moreover, performance is compared with a standard model predictive control approach.     

Degradation kinetics of monacolin K in red yeast rice powder using multiresponse modeling approach

The effects of storage temperature (4, 20, 30, 40, 50 °C) and atmospheric conditions in packages (vacuum, atmospheric) on degradation kinetics of monacolin K, an antihypercholesterolemic agent, in red yeast rice powder were investigated using multiresponse modeling approach. Storage of red yeast rice powder at 4 °C under vacuum package was found to enhance retention of monacolin K. Multiresponse modeling revealed degradation path of monacolin K acid form into their dehydromonacolin K and unknown product under vacuum package, while oxidized product was also formed under atmospheric package. Monacolin K lactone form and precursor were degraded into dehydromonacolin K lactone form, while degradation of dehydromonacolin K lactone form to unknown was more pronounced at temperature higher than 30 °C. Oxidized product was also generated from monacolin K lactone form in atmospheric package. High activation energy of monacolin K degradation in acid form indicated that degradation of monacolin K to their dehydromonacolin K was more susceptible to temperature change as compared to lactone form.     

Electronic Properties of SiB Nanoribbons in Density Functional Theory

Silicon - The present study investigates the electronic and magnetic properties of hydrogenated armchair/zigzag SiB nanoribbons with different widths. The calculations are carried out within the...