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Tunable diode laser absorption spectroscopy (TDLAS) is a method of using a tunable diode laser scanning one of absorption lines of trace gas, this technique has advantage of high sensitivity, fast response, multi-component and non-contact measurement. We had already developed a TDLAS sensor for monitoring natural gas leakage during the natural gas production and the process of gathering and transportation in the natural gas station, but in the practical application we found that the TDLAS sensor was influenced by visibility changes. In order to overcome this interference and improve sensor stability, we present an automatic control circuit to process photoelectric signal for eliminating interference of visibility changes. Long-term monitoring results show that the concentration of CH4 are regular and stable during the natural gas production and transmission, therefore the application of the automatic gain circuit improved the stability of the TDLAS sensor.

The complex dielectric behaviors of ferroelectric barium titanate (BT) ceramics were investigated. The dielectric properties were studied as a function of temperature and frequency using broadband dielectric spectrometer. The results show that the maximum value of dielectric constant occurs at 500nm BT ceramics, which is approximately 7,500; the dielectric loss is lower than 0.03 with the temperature varying from 225 K to 450 K. Dielectric constant and dielectric loss experience three dielectric peaks corresponding to rhombohedral to orthorhombic, tetragonal and cubic transitions. With the frequency ranges from 1 MHz to 1 GHz, the dielectric relaxation is apparently present. The relaxation process obeys Cole-Cole relaxation model at high temperature and conforms to Debye relaxation model when the temperature far lower than Curie temperature. The relaxation time is the order magnitude of ~10-9s obtained by Havriliak-Negami function fitting, which is very consistent with theoretical calculation.

Silicon carbide ceramic composite filter membrane materials were prepared by dry pressure molding and synchronous sintering process at sintering temperature of 1300oC for 3h. and research the influence of on the molding pressure structure of SiC filtration membrane,effect of particle size on porosity, average pore size and filter pressure drop of filtration membrane, SEM was performed to examine the morphology, The porosity ,average pore size and filter pressure drop of filtration membrane were tested by Archimedes method ,bubble point method and filter pressure drop instrument. It is demonstrated that while the molding pressure (F) varied from 1MPa to 10MPa, the filter membrane material achieved preferable morphology and best performance when F equals to 5MPa. Under this modeling pressure, while silicon carbide particle size increased from 1 to 23μm, the pore ratio decreased from 48.0% to 36.2% and the average pore size increased from 0.35μm to 9.4μm, while the air gas velocity changed from 0 to 0.112m/s, the filter pressure drop increased, when the velocity is stable, the filter pressure drop reduced as the silicon carbide particle size.

Barium titanate (BaTiO3) ceramics with grain size varied from 1000 to 8 nm were prepared by two step sintering method (TSS) and spark plasma sintering (SPS), respectively. Mixture structures of BaTiO3 ceramics were proved by in-situ temperature high resolution x-ray diffraction. Multiple ferroelectric domains present in nano-crystalline BaTiO3 ceramics were observed by transmission electron microscope. The evolution of phase transitions supported the existence of intrinsic mechanism. Dielectric loss of fine grain size BaTiO3 was higher than coarse grain size during Curie phase transition due to diffuse phase transition and grain boundary effects.

Synchronized Phasor Measurement Unit with CAN bus can be used to phasor acquisition and real-time dynamic monitoring of ship power system. As it is known to all, traditional CAN communication is based on event-triggered mechanism. Message transmission will be delayed when there are a lot of messages in CAN bus. This paper used TTCAN protocol to synchronize the master and slave clock nodes based on STM32 microcontrollers. A Fast Fourier transform of AD samples was been done and transferred to host computer through CAN bus which reflects the real-time running status of system well.

This article has used the equations of coupled heat-moisture anisothermal flow of the unsaturated soil, and conducted the numerical simulation coupling of heat and humidity by FLAC. By comparing the calculation result with the test result, it shows that the calculation result is close to the experiment result. The error is tending to be larger as the depth of the soil adds. The maximum error between the calculation and the experiment result is 1°C, and the smallest one is 0.1°C. Moreover due to the hysteresis of the heat transfer in the soil, the middle of the soil occurs temperature concentration phenomenon; Their trends of water migration variation are similar as the depth of the soil adds. The model of the coupling of heat and moisture is able to better simulate the change of heat and moisture of the soil under circulating action of temperature.

With the rapid development and versatile applications of nanotechnology, a large quantity of nanoparticles (NPs) has been released into the environment. It has been one of the most popular studies that concerning about the toxic effect of NPs on the organism of the total environment. This paper reviews the new results that reflect the impact of NPs on the algae. It also concludes the new researches from the fate and behaviors of the NPs, the ecotoxicology to the algae and the possible mechanism. Finally, there is an expectation concerning the study of toxicity of NPs to the algae, and propose what should investigate in future.

The influence of the heat loss of hot runner on the stability of mold injecting process was analyzed. Determine the lost power of heating elements by establishing of hot runner system. Using ANSYS codes to calculate the temperature control equations and get the temperature distribution of hot runner plate. Make the structural arrangement of heating pipes and thermocouples better and ensure thermal equilibrium of the hot runner system by analyzing the temperature field.

The optimal placement of PMU exerts very important influences on the application of Synchronized Phasor Measurement Technique in power system. In the paper, the optimal placement of PMU is firstly transformed into importance evaluation for the node. Then, PMU optimization algorithm of power system is proposed based on property evaluation of information entropy in connection with node importance evaluation. In the main idea of the algorithm, PMU is configured respectively according to importance order of each node in power system. As the experimental results show, attribute of se becomes the most important one in the property evaluation of information entropy. Contrasting original score Table 1 with the evaluation results Table 7, we conclude that final importance order for the node brings into correspondence with the score of attribute se, which proves the correctness of the algorithm eventually. Two methods of optimal placement of PMU raised in the end provide very strong instructive significance to the practices in reality.

BaZr0.25Ti0.75O3(BZT) ceramics were prepared by conventional ceramic process at a relatively low sintering temperature and with an addition of Li2O as the liquid-phase sintering aid. X-ray diffraction characterized results showed that the main crystal phase of the samples with 1.0wt% Li2O additive sintered at 1050°C～1250°C for 4h presented perovskite structure. The dielectric properties of BZT ceramics have been investigated. The dielectric constant of 1.0wt% Li2O doped BZT sintered at 1150°C decreased, and the dielectric loss increased by 0.0012 compared with that of the pure BZT sintered at 1450°C.

Loading management is one of the most important technologies for ship power system. Reasonable distribution of electric energy to the loading can achieve the goal of optimal energy schedule and its primary issue is to make a reasonable loading priority evaluation. This paper analyzed the shortcomings of the loading priority evaluation using the AHP and proposed a kind of algorithm of property weight evaluation based on PRISM classification, effectively combing expertise and characteristics of the objective data itself together. The results show that: the loading priority of ship power system is mainly affected by two properties of demand urgency and vulnerability. The results of various algorithms are basically consistent with the above conclusion, which proved the correctness of the algorithm. Comparison among various evaluation results tables shows that for the same weight measurement standard using different classification algorithm or property reduction algorithms, the results of its loading priority evaluation slightly differ.

Additives on low temperature compaction and performances of compacted mixtures, the author devised low temperature environment compaction test, and then, comparison tests of volume parameters, high temperature stability, low temperature crack resistance and water sensitivity were conducted. Tests results showed that the wax additives and the surface-active additive can significantly contribute to mixtures low-temperature compactibility. The wax additive helps to improve high temperature stability obviously, and has no significant contribution to low temperature crack resistance and water sensitivity. The surface-active additive directly reduces water sensitivity, the wax additive indirectly plays the role of reducing water sensitivity by increasing the density of mixture, and the foam additive has no obvious effect on the water sensitivity.