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We demonstrate a novel polarization control system based on a gradient descent algorithm, applied to a 450-km optical frequency transfer link. The power of the out-loop beat note is retrieved by controlling the polarization state of the transferred signal, with a recovery time of 24 ms, thereby ensuring the long-term evaluation of the fiber link. As a result, data utilization is enhanced from 70% to 99% over a continuous measurement period of ∼12 h. A fractional transfer instability of 7.2 × 10−20 is achieved at an integration time of 10000 s. This work lays the foundation for the comparison of a remote optical clock system via a long-haul optical fiber link.

Ho3+ with various concentrations and Tm3+ with molar concentration of 1.28% are co-doped in LiYF4 (YLF) single crystals. The luminescent properties of the crystals are investigated through emission spectra, emission cross section and decay curves under the excitation of 808 nm. The energy transfer from Tm3+ to Ho3+ and the optimum fluorescence emission of Ho3+ around 2.05 μm are investigated. The emission intensity at 2.05 μm keeps increasing with the molar concentration of Ho3+ improved from 0.50% to 1.51% when the molar concentration of Tm3+ is kept at 1.28%. Moreover, for the co-doped crystals in which the molar concentrations of Tm3+ and Ho3+ are 1.28% and 1.51%, respectively, the maximum emission cross section reaches 0.760×10−20 cm2 and the maximum fluorescence lifetime is 21.98 ms. All the parameters suggest that these materials have more advantages in the future 2.0 μm laser applications.

This paper presents a simple experimental method in determining the dynamic properties of concrete materials. The specimen used in the experiment was assembled with four disks, one of which was made from aluminum, the others concrete samples. Three manganin piezoresistive gauges were embedded in between the disks, from which pressure waves were recorded. The impact load was produced by using a light-gas gun. From the recorded pressure waves, stress, strain and particle velocity in the tested specimen were calculated. The experimental results showed that the peak pressure of the shock wave decreased exponentially with the propagation distance of the shock wave, whereas the width of the shock wave increased with propagation distance. The attenuation coefficient describing the peak pressure decay in a specimen was found to be close for specimens under different impact velocities and thus can be used to represent the viscosity of the concrete material.

This paper developed a Portable Agricultural Product Holographic Market Information Collection Terminal (APIC) which collected the holographic market information of agro-products, to address the issues such as undeveloped agricultural information collecting method, nonstandard collection criteria,imperfect classification and coding, as well as the lack of information collection device etc.. In the APIC system, there are two industrial standards on agro- product information collection embedded technology, and GPS positioning, integrated together with the general packet radio service(GPRS) and 3G mobile communications technology, making use of component development technology and embedded development technology, in order to achieve the standardization of data collection, instant transmission, and intelligent processing, and eventually to enhance the ability of integrated perception, decision-making and control in terms of monitoring and early warning of agro-products market price.

This paper presents the heat transfer simulation of a new kind of rotary engine called Leaf Spring Rotary Engine. The structure and the principle of the prototype engine were introduced. The thermodynamic models including heat transfer model were presented. The contrast of the performance parameters between the heat transfer condition and the ideal condition was presented and the effect of the heat transfer to the performance of the engine was analyzed. It showed that the heat transfer loss would account for 24% of the input energy at the rated speed of 3000r/min. At the same time, the effect of ignition position to the performance of the engine was analyzed. The work would be used in the combustion system design and the performance optimization.

This paper is a simulation study of a novel rotary engine called Leaf Spring Rotary Engine, which is a micro-small reed-flexible rotor engine. Flexible characteristics make it a unique advantage. This engine's structure is different to others, mainly for rotor structure. Engine working principle is similar to conventional rotary engine. As a new engine, creation of numerical models and analysis of impact factor for engine performance are the focus of this work. Desi*gned displacement of the engine is 1.77 cm 3 and theoretical compression ratio is 7.3. According to the principle of the engine, the whole structure and sub-system were designed, and thermodynamic model of the engine were established. Re*sults show that output power of one cylinder is 81.4W; indicative efficiency is 24.38% under ideal condition when engine operates at speeds of 3000 RPM; the energy loss under heat transfer condition is about 18.34% of the overall energy. The leakage area of 0.02 mm 2 is considered so that power loss induced by the leakage is about 32.4% of output power under ideal conditions. Besides, the results also show that the reasonable matching of combustion duration and ignition angle can improve output power. Moreover, high compression ratio of the engine causes high heat loss.