Abstract: To improve the accuracy of the transient temperature detection system, Transient temperature inversion processing algorithms is proposed based on spectrum analysis of speckle pattern interferometry. The interference fringes is formed by speckle interferometry in the system, and due to transient temperature changes cause the material strain, so that the speckle interference pattern changes. the interference fringes on the measured surface is obtained by the area array CCD collection before and after deformation. The corresponding spectrum density function will changes by the changes of transient temperature, and the amplitude changes of center wavelength is inverted by the speckle pattern interferometry. Through detecting and calculating the ratio of the amplitude of the center wavelength, the transient temperature can be obtained by spectrum analysis. In the analysis and calculation for the function of transient temperature and material strain, material strain and interference fringes, derived the amplitude and phase function of the transient temperature change and interference fringes, so as to provide the necessary conditions for detecting the use of spectral density function temperature. Experiment using 660nm laser diode, SI6600 type area CCD detector to obtain the speckle pattern interference fringes, system extracts the amplitude ratio of the central wavelength from spectral distribution function, and by calculation and calibration the detection accuracy of temperature can be achieved of 2°C. Compared to traditional methods that is direct detection for interference fringes changes, the new methods improve the accuracy by nearly an order of magnitude. It is more accurate detection and better uniformity, better stability.
Abstract: The mild-slope equation has widely been used for calculation of shallow water wave transformation. Recently, its extended version was introduced, which is capable of modeling wave transformation on rapidly varying topography. These equations were derived by integrating the Laplace equation vertically. Here, we develop a finite element model to solve the Laplace equation directly while keeping the same computational efficiency as the mild-slope equation. This model assumes the vertical variation of the wave potential as a cosine hyperbolic function as done in the derivation of the mild-slope equation, and the Galerkin method is used to discretize it. The computational domain is discretized with proper finite elements, while the radiation condition at infinity is treated by introducing the concept of an infinite element. The upper boundary condition can be either free surface or a solid structure. The applicability of the developed model is verified through example analyses of two-dimensional wave reflection and transmission. Analysis is also made for the case where a solid structure is floated near the still water level.
Abstract: This study investigates a friction damping bracing system in order to improve the response of steel frames when subjected to severe seismic excitations, beyond the design earthquake. A simplified model describing the behavior of the friction damper device was developed for global analyses of steel frames. Parametric analyses based on numerical simulations were carried out to evaluate the slip force with the aim of minimizing the values of top displacement and hysteretic energy dissipated by the steel frame. The main results of nonlinear dynamic analyses performed on a six-story steel frame incorporating friction damping bracing systems are presented and compared with the response of the unprotected counterpart. The effectiveness of the protection system was also assessed by examining the seismic response of the frame equipped with traditional braces, without friction devices. The results of the numerical investigations showed that the use of the friction damping bracing system caused an increase of the dissipative capacity of the frame, above all for high seismic actions. The plastic deformation concentrated inside the device, protecting the main structural elements from severe damage. The formation of the plastic hinges at the column base was delayed with respect to the unprotected frame. Numerical analyses indicated that the introduction of supplemental damping by using friction devices in steel bracings is very effective for seismic protection of steel frames subjected to severe seismic excitations.
Abstract: The paper approaches the influence problems, due to increase in plastic deformation and fracture initiation, upon the multi-axial stress state. The experiments are based on determining the geometric changes of stress concentrators and the increase of granulation anisotropy of unalloyed steel related to the plastic deformation. In order to evince the changes in the concentrators shape, at high levels of deformation, an average parameter of shape was introduced. The 3D Complex representations, based on measurements have indicated the dependence of longitudinal specific deformations for the deformation degree, as well as sectional position in the area under measurement. The variation functions of the longitudinal specific deformation of the medium average shape parameter showed an opposed linear dependence at the top of the tension concentrator relatively to the tested specimen axis. Taking into consideration the average parameter of shape, the experimental correlations were more conclusive. Evaluating the microstructural state of stress concentrators, the deformations have revealed distinct fracture typologies, influenced by the specific state of deformation. By synthesizing the information regarding the fracture initiation, an typological diagram of fracture initiation TDI was elaborated. In this diagram, representing the cross section of the specimens, for different values of the stress concentrator factor, six quasi-quantitative zones have been analyzed.
Abstract: At present there are many studies that are carried out to develop micro parts. A micro drive unit assembled with several micro movable parts is needed to industrialize the functional micro parts such as micro pump, micro-chip, micro motor, and micro gear. In this study, a powder injection molding process was used in making micro metal gear with outer diameter of 500um. To make micro metal parts, it necessary to create micro shape cavities and cores for the filling of feedstocks. To make micro shapes or patterns, there are several methods to choose such as LIGA, laser machining, micro etching, and micro milling. But these micro methods are expensive and need some special facilities to fabricate. So in this study, conventional machining methods were tested to make micro gear cavity shapes. The preliminary studies were conducted to evaluate the filling of cavity and the EDM machining. Finally micro gear with outer diameter of 500um was injection molded, de-binded, and sintered. Some incomplete fillings occurred at the end of filling gear teeth using 17-4PH 3F feedstock. The final sintered micro metal gear showed about 434um of outer diameter.
Abstract: Due to its intermittent behavior wind speed supposes a WTG generating model of more than two states. Uncertainty in wind power implies a non-constant power output; hence, there are a risk of loss of capacity and loads. This paper proposes a multistate model of wind generating unit, to include the effect of wind variability besides conventional generators in HL1 reliability evaluation. Through non-sequential Monte Carlo simulations it is shown that system performance decreases as a result of wind power inclusion, and reliability indices validate it. Markov process is used to design the multistate model of wind generating unit. Historical data wind velocity for sixteen past years is gathered and used for modeling, and as case study a demand data in north of Colombia is selected.
Abstract: In the present study, the failure of basic redundant steel structural systems is investigated. By considering that each member of the system has brittle, semi-brittle, or perfectly plastic properties, the statistical behavior of perfectly brittle systems, semi-brittle systems, perfectly plastic and combination systems are evaluated, and the effects of the coefficient of variation (CoV) of members on the systems are investigated. Uncorrelated strengths with the same mean are considered for the system elements. By using the Monte Carlo simulation (MCS) method, maximum strength, yield strength and residual strength of the redundant steel structural systems are evaluated. The CoV of member strength is an essential parameter for statistical assessment of steel structural systems. In this study, the strength is defined random variable a selected normal distribution represents the random variable, for the member strength. The deformation capacity of the member is strongly depends to the characteristics of member strength, but the post failure factor has deterministic values, only for the combination system. The post failure factor is a random variable that represents the uncertainty, uniform distribution is selected to represents random variable, in combination system post failure factor.
Abstract: The construction of reinforced concrete (RC) buildings with flat-slab systems has become widely used in some high seismicity European countries. This type of structure is particularly common both for office and residential buildings, taking advantage of the reduced floor height to meet economical and architectural demands. Even though some national codes may include rules for the design of these structures, the provisions of Eurocode 8 don’t cover flat-slab frames used as part of the lateral load resisting system. Main results of seismic analyses performed on a six-story RC flat-slab structure are reported in this study. The structural response was predicted using both nonlinear static and dynamic analyses with artificial ground motion records with increasing intensity levels. Different seismic retrofit techniques were applied to enhance the seismic performance of the structure including: 1) insertion of shear wall; 2) confinement of column plastic hinge regions using FRP wrapping; 3) addition of RC column jackets. The predicted seismic performance of the retrofitted models was compared to that of the unretrofitted counterpart. Numerical investigations provide information about the seismic performance of a common type of RC structure not covered by the provisions of Eurocode 8 as well as the potential to mitigate the damage for varying earthquake intensity levels through different retrofit techniques.
Abstract: This paper proposes a charging algorithm which is based on the Estimation of Distribution Algorithm (EDA) for Plug in Hybrid Electric Vehicle (PHEV). The proposed algorithm shifts the peak of power supply, satisfies the requested State of Charge (SoC [%]), and minimizes the charging cost. The proposed algorithm uses flexible weight for charging and upper charging limit to each PHEV to minimize the charge amount in peak time. The simulation result shows that the proposed algorithm shifts the peak of power supply in commute time zones, satisfies SoC of 93% PHEVs, and reduces charging cost by 31% compared with conventional EDA algorithm.