Logistics cost analysis of rice straw pellets for feasible production capacity and spatial scale in heat utilization systems: A case study in Nanporo town,Hokkaido, Japan

Rice straw is a promising renewable energy source because it is abundantly available in Asia. This study conducted a case study of logistics cost analysis for rice straw pellets by considering all stages in the supply chain to define the main factors affecting the selling price of rice straw pellets: collection (job-commission or employment of part-time workers), transportation, storage (vinyl greenhouses or storage buildings with larger capacity), pelletizing, and delivery to users with biomass boilers. The selling price was found to be strongly dependent on the production capacity because the investment cost for the pellet production facility had a significant effect of economies of scale. A production capacity of larger than 1500 t y⁻¹ is required for rice straw pellets to compete with wood pellets and fossil fuels in the studied Japanese context if the subsidy rate for the investment is 50%, part-time workers conduct the collection, and rice straw is stored in the storage buildings. Our sensitivity analysis also showed an economically feasible spatial scale: for example, rice straw should be collected within a 20 km radius and the users should be within a 38 km radius when the production capacity is 1500 t y⁻¹. In addition, other critical factors related to the collection of rice straw from the paddy fields and transportation of rice straw rolls to storage were identified as planning factors to further reduce the total logistics cost of rice straw pellets.     

High selectivity of erythritol production from glycerol by Yarrowia lipolytica

The effect of different vitamins and nitrogen sources on the yield, productivity and selectivity of erythritol production from glycerol in batch and fed-batch cultures by Yarrowia lipolytica Wratislavia K1 strain was examined in the study.Thiamine was a vitamin necessary for efficient erythritol production and the yeast extract (YE) turned out to be its best source. The YE was additionally a very good source of nitrogen in this process. Erythritol production may be efficient in the media containing only yeast extract and crude glycerol. The application of a high substrate concentration (325 kg m⁻³) in the fed-batch system with pulsed addition of glycerol resulted in erythritol production of 201.2 kg m⁻³ after 168 h of cultivation. The mass fraction of by-products, such as other polyols and organic acids, did not exceed 10%. The study showed that by-products formation could be significantly reduced by the addition of a nitrogen source after glycerol depletion from the media. Wratislavia K1 strain does not utilize erythritol in the presence of other carbon sources and this feature was used in order to increase product selectivity up to 99.7% and protein content in yeast biomass up to 28.7%. The factors determining the use of biomass as animal feed, i.e. protein concentration and presence of metal ions, were discussed as well.     

A new wireless ad hoc multicast routing protocol

An ad hoc network is a multi-hop wireless network of mobile nodes without the intervention of fixed infrastructure. Limited bandwidth and mobility require that ad hoc routing protocols be robust, simple, and energy conserving. This paper proposes a new ad hoc multicast routing protocol called neighbor-supporting multicast protocol (NSMP). NSMP adopts a mesh structure to enhance resilience against mobility. And NSMP utilizes node locality to reduce the overhead of route maintenance. NSMP also attempts to improve route efficiency and reduce data transmissions. Our simulation results show that NSMP delivers packets efficiently while substantially reducing control overhead in various environments.     

Effects of components in culture medium on glutamate decarboxylase activity and γ-aminobutyric acid accumulation in foxtail millet (Setaria italica L.) during germination

The effects of glutamic acid (Glu), pyridoxal-5-phosphate (PLP) and calcium chloride (CaCl₂) in culture medium on glutamate decarboxylase (GAD) activity and γ-aminobutyric acid (GABA) accumulation in foxtail millet (Setaria italica L.) during germination were investigated in this study. The components in culture medium for GABA accumulation were optimised using response surface methodology (RSM). Results showed that GAD activity and GABA yield were dependent on the addition of Glu, PLP and CaCl₂ into the culture medium. Box–Behnken design indicated that the optimal culture components for GABA accumulation were: Glu at a concentration of 1.2 mg/ml, PLP at a concentration of 50 μM and CaCl₂ at a concentration of 2.5 mM. Under the optimal conditions, the maximal production of GABA (42.9 mg/100 g FW) was obtained. Analysis of variance for the regression model suggested that the model can quite exactly predict GABA accumulation in millet during germination.     

A graphical method to determine the harmonic magnification in radial feeders due to SVC operation

Static var compensators (SVC) are used widely in power systems. Their disadvantages are the harmonic generation and, under certain operating conditions, SVC interacts with the power system. This interaction may magnify some of the harmonic components. This paper represents a graphical method that explores the effect of SVC's parameters and operating point on the voltage quality at load's bus bar due to the harmonic component magnification. This method overcomes the need to solve the system's non-linear state equations and/or the use of EMTP program to investigate the possibility of harmonic magnification occurrence in a particular radial feeder. The method also determines the critical value of SVC inductance to avoid harmonic magnification. The method is applied to a radial feeder in the state of Massachusetts, USA. The results are reported with a comparison to EMTP results.     

A correlation concept for the energy cost: a case study in Egypt

This paper presents two factors for the correlation of energy cost. The first factor is based on the process of accounting and the cycle of recording the readings of consumption in order to control the exact cost of energy. A sample for the domestic customers in Egypt within 20 years has been included in the investigation and analyzed. The mathematical analysis is deduced. Another sample for the load curves in Port Said City is inserted and investigated. The statistical performance for the readings of the presented load curves is deduced and the results are discussed. A second correlation factor for pricing the energy is proposed to cover the engineering effect in the technical process of operation. It correlates the automatic random variation in loads of customers and the load curves on the statistical base. The mathematical analysis for either average price of consumed energy or the statistical average loads, with the variation of load curves characteristics, are presented.     

Synthesis and physicochemical investigation of imide-functionalized silica nanocomposites

The incorporation of inorganic nanoparticles into polymers have gained significant attention to improving functional properties. The ultimate nanocomposite behaviors are influenced by many parameters, such as microstructural distribution that are produced during the treatment process. Herein, a hybrid material integrating a modified network into a polyimide PI matrix was produced via the sol–gel method by the reaction of pyromellitic dianhydride, 4, 4-oxydianaline, and 1, 5-diaminonaphthalene to synthesize copolyimides nanocomposite. The modified polyimide and unmodified polyimide silica (SiO₂) nanoparticles were incorporated in the polyimide matrix to have polyimide silica nanocomposite. In modified silica nanoparticles, 3-aminopropyltriethosilane was introduced to have better compatibility among inorganic–organic hybrid with similar chemical contact due to their flexible alkyl group. The surface morphology or structure of silica and polyimide was affirmed by scanning electron microscopy, Fourier transforms infrared spectroscopy confirmed the synthesis of pure polyimide, unmodified polyimide, and modified polyimide silica via presence and absence of certain peaks. Thermogravimetric analysis (TGA) results showed high thermal stability of nanocomposites as silica content increases. In contrast to unmodified silica, the modified silica provides more thermal stability to the nanocomposites. Dynamic mechanical analysis was used to investigate the tensile stress of pure polyimide, unmodified, and modified silica nanocomposites. Thermal stability, storage modulus, and moisture absorption of these hybrid materials were improved with silica nanoparticles. The TG mass spectrum confirms the successful synthesis of modified silica networks. The substituted silica nanoparticles show higher mechanical toughness and storage in modified compared to unmodified silica nanocomposite, which exhibits stronger binding attraction between silica nanoparticles and polyimide matrix.     

产亚油酸异构酶菌株的诱变选育及其酶学性质研究

以保加利亚乳杆菌为出发菌株,经紫外诱变选育,获得2株高产酶突变株A1及A2,其酶活分别为30.1U/mL、32.1U/mL,酶活较出发菌株分别提高45%和54%.酶学性质研究表明,A2菌株产亚油酸异构酶的最适反应温度分别为40℃,最适pH 6.5,酶在低于40%时具有良好的热稳定性,pH 6.0～7.0时较稳定.以Lineweaver-Burk双倒数作图法求得亚油酸异构酶的Km为0.039 mmol/L,Vmax为0.24mmol/(h·mg).