Advanced Materials Research Vols. 301-303

Abstract: Cyclic axial loads in steel tubular might lead to local buckling, wrinkling and accumulation of plastic strains in the tube. During their life time steel tubes may also experience different types of material loss such as corrosion or thinning. This paper deals with the effects of corrosion defects on the strain ratcheting response of steel tubes. Small scale un-corroded and corroded tubular specimens have been tested under monotonic and cyclic axial loads. Optical system ATOS has been used for 3D surface acquisition and reconstruction of the tested specimen and to evaluate their strain ratcheting and wrinkling response. This is a camera-based triangulation system. A processing unit employs optical transform equations to automatically and with a great accuracy calculate 3D coordinates for every pixel of camera. Depending on camera resolution as an effect of such a scan a cloud of up to 4 million points has been obtained for every single measurement. From the results, it has been noticed that the possibility of ratcheting or progressive plastic failure substantially increases by the presence of the corrosion defects. With the corroded specimens, the strain ratcheting behaviour in the defected zone has been distinctively different from that in the perfect zones.

Abstract: We are presenting the work progress and recent results in a development and construction of new technologies for submillimeter laser ranging and picosecond accuracy laser time transfer. The key hardware components: the Start detector and discriminator, the echo signal detector, the timing device and signal cablings were studied in detail. The new devices have been designed, built and tested in our lab. To minimize the systematic errors the photon counting approach has been selected. The ranging chain has been designed and optimized with a goal of single shot resolution of several millimeters and sub-millimeter normal points and overall system stability. The Start detector and discriminator are constructed as a single device to optimize their matching and maintain stability. The NPET timing system based on surface acoustic wave interpolator has a resolution of 800 fs and 4 fs long term stability. The echo detector is based on innovated SPAD detector optimized for high repetition Gate rate and minimal dark count rate. Both the detectors output signals have ultrafast slew rates < 200 ps / 1 V. In connection to the 6 GHz bandwidth of the timing system inputs these fast slew rates improves the timing and temperature stability along with the RF interference immunity. The new low temperature drift signal cables have been selected, tested and used. The new hardware was tested in indoor calibration experiments. We have achieved the single shot resolution of 3 mm rms. The temperature and temporal stability of the individual components is excellent. The drift is typically below 200 fs/K for each contributor. The overall temperature drift of the entire laser ranging chain is below 500 fs/ K. The long term stability of the ground target calibration is better than ± 800 fs within 3 days. During this period the environment temperature changed by more than 4°C. In the sense of time deviation Tdev the stability of 300 fs was achieved. The presented components will enable to carry out laser ranging with submillimeter normal points stability and reproducibility. The accuracy of the “ranging machine” based on these devices will reach sub-mm values, as well. The concept and construction will be presented along with the achieved devices parameters.

Abstract: The frequency-sensitive optical response due to two-photon resonance of electromagnetically induced transparency (EIT) in a tunable band structure of an EIT-based layered medium is considered. The unit cells of this periodic layered structure are composed of dielectric (e.g., GaAs) and EIT atomic vapor. The frequency-sensitive behavior of controllable reflectance and transmittance depending on the external control field can be applicable to new device design (e.g., it can serve as the fundamental working mechanism for photonic switches and photonic logic gates). Some two-input logic gates (e.g., OR and NAND gates) are designed based on the present effect of sensitive switching control that results from the two-photon resonance.

Abstract: With the analysis of existing workflow engine based on monolithic kernel, a workflow engine which is based on micro kernel is designed. Service implementation and activity scheduling are separated by the engine, and then the micro kernel layer is independent and stable. All this decreased cost of engine reconstruction and difficulty of maintenance; the engine is constructed by component-based development techniques and finite state machine, which reduce the coupling between system components and increase the flexibility of workflow engine.

Abstract: The influence of fixing adhesives on strain performance of fiber Bragg grating (FBG) sensor was investigated. A FBG sensor was fixed on the uniform strength beam with three kinds of adhesives, which are modified acrylate, glass glue and epoxy resin. The linearity, sensitivity and their stability of FBG sensor fixed by three kinds of adhesives were measured and analyzed at the temperatures 0^ºC-40^ºC. The results show that, the FBG sensor fixed by the modified acrylate has a high linearity, sensitivity and stability at different temperatures. The FBG sensor fixed by the glass glue also has a high linearity and stability, but it has a low sensitivity. When the FBG sensor is fixed by epoxy resin, the sensitivity and linearity is affected significantly by the temperature. In addition, the performance of the FBG sensor fixed by the modified acrylate has a good stability for a certain period of time.

Abstract: Study on the tea aroma components is greatly significant, which are important factors in tea quality valuation.In recent years, nine main methods are under consideration：simultaneous distillation and solvent extraction, vacuum distillation extraction, steam distillation under reduced pressure, headspace analysis, solid-phase micro-extractions, headspace solid-phase micro-extractions, tea liquid absorption, supercritical fluid extraction and electronic nose. Meanwhile, advantages and disadvantages of each method were analyzed, in order to conduct technological guidance on the extraction and separation technologies in tea aroma components and provide a theoretical basis in improvement of each method.

Abstract: Pulsed eddy current (PEC) technique has been successfully used for measuring wall thinning of carbon steel equipments without removal of the insulation. In field applications, the probe performance decreases in presence of ferromagnetic claddings. This paper presents a method based on saturation magnetization to solve this problem. The main principle of this method is to weaken the magnetic shielding effect of the cladding by magnetizing it to saturation. A U-shaped magnetizer is designed to realize this method. Contrast experiments are performed on a Q235 steel plate covered by a galvanized steel cladding. The experiment results show that the thickness measurement range and lift-off range are increased by applying this method to the common PEC probe.

Abstract: Combining with the current development trend of vehicle suspension and damper technology, different standards of MR dampers are respectively developed in this paper in order to solve problems the semi-active suspend engineering application brings, where its structure design of a certain type of MR damper is detailedly analyzed from the point of engineering view. In order to speed up the progress of MR damper development, based on 1/4 suspend hardware-in-the-loop tester, the integrated developing platform for MR damper with embedded controller is designed and developed, in which some key parts are included, such as assistant algorithm of structure design, exploitation tool of speediness testing, communication interface of CAN bus. The integrated developing platform for MR damper with embedded controller is the same with MR product’s exploitation flow. Finally, its hardware and software design of the measuring-controlling unit for MR damper with embedded controller, are introduced, and some test results are also show and analyzed. Experimental results prove that the developed MR damper with embedded controller would have a widely application prospect.

Abstract: Using the developed hardware-in-the-loop simulation platform for weapon system under impact load excitation and a novel large-scale single-ended MR damper without the accumulator, impact tests for the special designed long-stroke magnetorheological recoil damper were done and its dynamic performances under different impact loads and input current were examined in this paper. Model of damping force was established by using the model reference adaptive control method. Its dynamic performances of MR damper under model reference adaptive control strategies were analyzed by numerical simulations and tests. Experimental results show that the model reference adaptive control method could reduce its peak value of recoil damping force to 27.33% and its peak value of stroke to 48.75%, and its adjustability of damping force could be well applied for its impact resistance design of gun recoil mechanism.

Abstract: The problem of target detection which is affected by the direct wave is discussed in this paper. Singular Value Decomposition method is proposed for removing the direct wave. The echo signal is decomposed by use of Singular Value Decomposition method and the one-order eigenvalue of the eigenvalue matrix is set to zero, then the related components of echo signal are removed. The direct wave signal can be removed effectively using this method, and most of the target components of signal are preserved in the process of removing direct wave signal. HFSS simulation software is used for modeling and simulation, and the results show that the resolution of false target using Singular Value Decomposition method increases 11% compared with the Interference Canceling method for removing direct wave.