Design and implementation of Type-2 fuzzy neural system controller for PWM rectifiers

It is necessary to convert AC to DC for the systems that do not work with AC sources. For this reason, diode and thyristor rectifiers were developed and designed. However, these rectifiers are not well suited for industrial applications requiring high performance. With the advances in power electronics and semiconductor technology, Pulse width modulation (PWM) rectifiers have been successfully employed in various industrial applications including variable-speed drives and uninterruptible power supplies. PWM rectifiers have the advantages of being low input current harmonic, adjustable input power factor, and controllable DC voltage and bidirectional energy flow. Because of all these features of the PWM rectifiers, the control and design of these rectifiers are very important topic. The aim of this paper is to control DC-link voltage of PWM rectifier with type-2 fuzzy neural system (T2FNS) instead of PI controller. For this aim, three-phase PWM rectifier with proposed controller is designed and simulated for four scenarios in this paper. A simulation model of the PWM rectifier is designed in MATLAB/Simulink and the performance of PWM rectifier with proposed controller is analyzed.     

Briquetting soda weed (Salsola tragus) to be used as a rural fuel source

Amount of traditional fuel sources in the world has been decreasing and there is a definite need to produce and utilize alternative fuels such as biomass materials. In this study, briquetting conditions of Russian tumbleweed, Salsola tragus, (commonly named soda weed in Turkey) which grows in salty soils were investigated.Soda weeds were first chopped coarsely in a local tresher, then chopped finely in a hammer mill. Weed materials at three moisture levels (7%, 10%, and 13%) were prepared in the lab. Chopped weed materials were filled in cylindrical and square dies and compressed using a hydraulic press at three pressure levels of 15.7, 19.6 and 31.4 MPa. Optimum temperature, moisture rate, and pressure values were determined to produce stable briquettes. Further experiments were conducted to produce briquettes using sawdust and walnut shells as additives in conical dies of two different sizes.Results of a statistical analysis of parameters to produce briquettes in different dies indicated that moisture rates of 7–10%, pressure of 31.4 MPa, and temperatures of 85–105 °C were suitable for briquetting soda weed. Furthermore, sawdust and walnut shells additives increased briquette density without any negative effects on production process and product stability.     

Manufacture of Turkish Beyaz cheese added with probiotic strains

The survival of the probiotic strains Lactobacillus fermentum (AB5-18 and AK4-120) and Lactobacillus plantarum (AB16-65 and AC18-82), all derived from human faces, was investigated in Turkish Beyaz cheese production. Three batches of Turkish Beyaz cheese were produced: one with the test probiotic culture mix (P), another with a commercial starter culture mix including Lactoccocus lactis subsp. cremoris, Lactococcus lactis subsp. lactis (C) and the third with equal parts of the commercial starter culture mix and test probiotic culture mix (CP). The cheeses were ripened at 4 °C for 120 days and the viability of cultures was determined monthly. Cheese samples were analyzed for total solids, fat in solids, titratable acidity, pH, salt in total solids, proteolysis, sensory evaluation, aroma compounds and biogenic amines. While initial lactic acid bacteria load in P cheese was 2.7 × 10⁹ at the beginning, it was 7.42 × 10⁷ cfu/g at the end of 120 days of ripening. The results showed that test probiotic culture mix was successfully used in cheese production without adversely affecting the cheese quality during ripening. The chemical composition and sensory quality of P cheeses were also comparable with C cheeses. The present study indicates that probiotic cultures of human origin are feasible for Turkish Beyaz cheese production.     

Determination of Transglutaminase Activity Using Fluorescence Spectrophotometer

An improved fluorometric assay for determining the activity of the microbial transglutaminase (TGase) in the culture medium samples has been developed. The assay procedure measures the fluorescence enhancement due to the incorporation of monodansyl cadaverine (Substrate A) into pentafluorophenylester of CBZ-Gln-Gly (Substrate Q) at λ_exc. 260 nm and λ_em 538 nm. The effect of the competitive inhibitors in the culture medium samples on TGase activity was determined. The assay was combined with HPLC method for determining enzyme activity as an international unit (IU). Enzymatic reaction was monitored by HPLC and the rate of product formation was measured via amine substrate consumption rate. A conversion factor was obtained using HPLC and fluorescence spectrophotometer data together. This was formulated for quantification of TGase activity as IU using fluorometric assay reported in this study. The detection limit of the assay was determined as 0.0014 IU (0.5 mg). TGase activity remained linear upto the enzyme concentraion of 20 mg. This technique dramatically decreases the incubation time of enzyme to a few minutes of activity measurement.     

共反应剂法均相合成长链脂肪酸纤维素酯

在纤维素(棉浆粕)的LiCl/N,N-二甲基乙酰胺均相溶液中,以对甲苯磺酰氯(TosCl)为共反应剂,原位活化长链脂肪酸,合成了长链脂肪酸纤维素酯;采用FTIR、1H NMR、XRD和热重分析等手段对产物进行了表征;考察了长链脂肪酸中的碳原子数、反应物配比、反应温度、反应时间等因素对产物取代度的影响。实验结果表明,当n(反应物纤维素葡萄糖苷)∶n(长链脂肪酸)∶n(TosCl)=1∶3∶3、反应温度85℃、反应时间24h时,产物取代度较高;且随长链脂肪酸碳原子数目的增加,产物取代度下降。表征结果表明,与纤维素相比,长链脂肪酸纤维素酯的结晶度下降,使其在有机溶剂中的溶解性增强;酯化反应削弱了纤维素分子间及分子内的作用力,赋予了长链脂肪酸纤维素酯较低的热加工温度。     

Special Features of the Kinetics of Boriding of Binary Fe – Ni Alloys

Metal Science and Heat Treatment - The kinetics of boriding of Fe – Ni alloys containing 60, 70, 80, and 90 wt.% Ni at 1073 – 1373 K for 2 – 8 h in powdered mixtures with the use...     

Arsenic removal from drinking water by electrocoagulation using iron electrodes

Arsenic removal from drinking water was investigated using electrocoagulation (EC) followed by filtration. A sand filter was used to remove flocs generated in the EC process. Experiments were performed in a batch electrochemical reactor using iron electrodes with monopolar parallel electrode connection mode to assess their efficiency. The effects of several operating parameters on arsenic removal such as current density (1.5–9.0 mA cm^?2), initial arsenic concentration (50–500 μg L^?1), operating time (0–15 min), electrode surface area (266–665 cm²), and sodium chloride concentrations (0.01 and 0.02M) were examined. The EC process was able to decrease the residual arsenic concentration to less than 10 μg L^?1. Optimum operating conditions were determined as an operating time of 5 min and current density of 4.5 mA cm^?2 at pH of 7. The optimum electrode surface area for arsenic removal was found to be 266 cm² taking into consideration cost effectiveness. The residual iron concentration increased with increasing residence time, and maximum residual iron value was measured as 287 μg L^?1 for electrode surface area of 266 cm². The addition of sodium chloride had no significant effect on residual arsenic concentration, but an increase in current density was observed.     

月桂酸纤维素酯的均相法合成

在纤维素LiCl/N,N-二甲基乙酰胺(DMAc)均相溶液体系中,以对甲苯磺酰氯(TosCl)为共反应剂,原位活化月桂酸,合成了月桂酸纤维素酯。采用红外光谱、核磁共振、热重等分析手段对产品进行了表征。考察了反应物配比、温度、时间等酯化条件对产品取代度的影响。结果表明:酯化产品的取代度与反应物纤维素葡萄糖苷、月桂酸和对甲苯磺酰氯的配比、反应温度及反应时间有关。在最佳酯化条件下,所得产品的取代度(DS)为2.58。热重分析结果表明,酯化反应削弱了纤维素分子间及分子内的作用力,赋予了月桂酸纤维素酯较好的热加工性。月桂酸纤维素酯在有机溶剂中的溶解度随取代度的增加而提高。