Advanced Materials Research Vols. 317-319

Abstract: Active power filter (APF) is an important device to compensate harmonic and reactive current in power system control method adopted has a great influence on its performance. The paper introduces several control methods used by APF, including the deadbeat control, single-cycle control, space vector control and so on. After comparing and analyzing their individual advantages and disadvantages, some improvements for APF performance are proposed.

Abstract: A new technique of using Optical Time Domain Reflectometry (OTDR) to detect the reflected power of FBG sensing array was researched systematically. The theoretical model between the reflected power detected by OTDR and the reflected wavelength of FBG was established by analyzing, and consequently the selection rule of FBG wavelength in OTDR detection system was proposed. Moreover, experiments about multi-combination of FBGs with high reflectivity were carried out. The cause of dummy peak and resonance peak in OTDR test curves were analyzed, and meanwhile the selection basis of FBG reflectivity was also given. Based on time division multiplexing theory, detecting low-reflectivity FBG by OTDR can increase the FBG multiplexing number greatly, which has wide prospect to be applied in FBG array detection.

Abstract: Using waste polyacrylonitrile fibers as raw materials. After the polyacrylonitrile fibers was hydrolyzed by NaOH and was grafted by PEG, H-PAN grafted PEG phase change fibers were prepared by wet spinning . The spinning process of the phase change fibers was observed, and the best spinning process was determined. Discussed the mechanical properties of the phase change fibers on the spinning solution concentration, crosslinker concentration, coagulation bath concentration and coagulation bath temperature. Temperature adaptable and durability properties of phase change fibers were characterizated by step cooling curves. The results showed that the best spinning process of the phase change fibers was the spinning solution concentration 20%, crosslinking agent concentration 4%, the concentration of coagulation bath 90%, the solidification temperature 30°C. The phase change fibers had good temperature adaptable property and temperature adaptable durability.

Abstract: In this paper, some new algorithms based on diagonal blocks of reachability and observability Gramians are presented for structure preserving model order reduction on second order linear dynamical systems. They are more suitable for large scale systems compared to existing Gramian based algorithms, namely second order balanced truncation methods. In experiments, they have similar performance as the existing techniques.

Abstract: Introduce the practicality of automatic angle modulation cooling fan used in the engine cooling, calculate the performance data when automatically adjusting angle fan in different installation angle during operation by Fluent, do a comparison analysis of the data, draw the curves of cooling fan flow-total pressure and flow-efficiency in the different installation angle, make sure the operation law of the fan and the range of adjusting angle, and proof the automatic angle modulation cooling fan meet the requirement of the engineering machinery engine cooling, adapt to the working conditions of engineering machine.

Abstract: Based on sufficient market research, a new model of self-unloading semi-trailer, whose maximum loading capacity is 30 tons, has been designed. The paper describes its overall structure, the three-dimensional diorama model and the finite element model of the frame. Based on the analysis of the models and the results of the calculation, the parameters of the frame are optimized. The advantages of the new design are as follows: the new design makes the most of the advantages of self-unloading trailers and semi-trailers, that is, self-unloading, security, stability, high efficiency, environmental protection.

Abstract: Nowadays we mainly take a method with proportion-coefficient basing experience to predict the carrying maintenance spare parts of armored equipments in wartime. However, the method does not accord with the expending law of maintenance spare parts in wartime. So in the paper we take support degree model and a method with phase support degree to define the rough carrying amount firstly for settling the problem. Then we take marginal utility analysis basing the restriction of transporting capability to optimizing the carrying amount of spare parts in wartime.

Abstract: The crayfish flavoring was prepared from pretreated crayfish residues after enzymatic hydrolysis, fermentation with Lactobacillus helveticus, complex formulation with auxiliary odoriferous spices from spice plants and food additives, homogenization and sterilization. The results of orthogonal experiments showed that the content of the flavor agent alkyl pyrazine in the fermentation broth was 0.54ng/mL. The product with tastiness of crayfish, nutrition and biological activity functions was obtained when the contents of taurine, soluble peptide and the nitrogen of the free amino acid in the crayfish flavoring were 0.025g/100g, 1.41g/100g and 0.66g/100g, respectively.

Abstract: The two controlled inoculation procedures of simultaneous and sequential fermentations with Saccharomyces Cerevisiae DJ02 and Lactobacliius acidophilus WS were studied in pear wine. The sugar consumption and ethanol product were delayed in the course of simultaneous fermentation contrary to the single fermentation. However in the sequential fermentation the effect was less than the simultaneous fermentation. In this work the function of malic acid degradation in the sequential fermentation was better than the simultaneous fermentation. The pH value of the pear wine came to 3.9 after the sequential fermentation. The change tendency of the yeast population after adding Lactobacliius acidophilus WS was similar to the yeast single fermentation in the simultaneous and sequential fermentation. But the cell population was went down in the course of the fermentation. The population of Lactobacliius acidophilus WS in the course of the two kinds of fermentation methods showed no significantly differences.

Abstract: A relay feedback identification autotuning PID/PI is proposed in this paper which is capable of controlling long time-delay processes. The real process is approximated via FOPDT or SOPDT models, whose parameters are specified through a modified relay feedback identification method. Applying zero-pole cancellation principle, the PID/PI is tuned according to the specified amplitude and phase margins. Model identification and controller parameter tuning are done on-line without much influence on the normal operation.