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This paper presents the design of nonlinear servo systems using the fuzzy method. The idea behind this control method is to divide the operating region of a nonlinear system into a collection of local linear servo control systems and apply the fuzzy method for calculation of the control input. The control input of each local linear servo system is calculated using the Davison–Smith method and the Hikita pole assignment method. We can prove that all states of the fuzzy servo system are bounded and that the output errors converge to zero by the Lyapunov method. Simulations on a nonlinear mass‐spring‐damper system illustrate the effectiveness of the proposed method. 相似文献
54.
Mei-Ling Chong Nor' Aini Abdul Rahman Raha Abdul Rahim Suraini Abdul Aziz Yoshihito Shirai Mohd Ali Hassan 《International Journal of Hydrogen Energy》2009,34(17):7475-7482
Clostridium butyricum EB6 successfully produced hydrogen gas from palm oil mill effluent (POME). In this study, central composite design and response surface methodology were applied to determine the optimum conditions for hydrogen production (Pc) and maximum hydrogen production rate (Rmax) from POME. Experimental results showed that the pH, temperature and chemical oxygen demand (COD) of POME affected both the hydrogen production and production rate, both individually and interactively. The optimum conditions for hydrogen production (Pc) were pH 5.69, 36 °C, and 92 g COD/l; with an estimated Pc value of 306 ml H2/g carbohydrate. The optimum conditions for maximum hydrogen production rate (Rmax) were pH 6.52, 41 °C and 60 g COD/l; with an estimated Rmax value of 914 ml H2/h. An overlay study was performed to obtain an overall model optimization. The optimized conditions for the overall model were pH 6.05, 36 °C and 94 g COD/l. The hydrogen content in the biogas produced ranged from 60% to 75%. 相似文献
55.
Hussein Saad Amr Mohamed Tamer ElBatt 《Wireless Communications and Mobile Computing》2015,15(15):1929-1944
In this paper, we address the problem of distributed interference management of femtocells that share the same frequency band with macrocells using distributed multi‐agent Q‐learning. We formulate and solve two problems representing two different Q‐learning algorithms, namely, femto‐based distributed and sub‐carrier‐based distributed power controls using Q‐learning (FBDPC‐Q and SBDPC‐Q). FBDPC‐Q is a multi‐agent algorithm that works on a global basis, for example, deals with the aggregate macrocell and femtocell capacities. Its complexity increases exponentially with the number of sub‐carriers in the system. Also, it does not take into consideration the sub‐carrier macrocell capacity as a constraint. To overcome these problems, SBDPC‐Q is proposed, which is a multi‐agent algorithm that works on a sub‐carrier basis, for example, sub‐carrier macrocell and femtocell capacities. Each of FBDPC‐Q and SBDPC‐Q works in three different learning paradigms: independent (IL), cooperative (CL), and weighted cooperative (WCL). IL is considered the simplest form for applying Q‐learning in multi‐agent scenarios, where all the femtocells learn independently. CL and WCL are the proposed schemes in which femtocells share partial information during the learning process in order to strike a balance between practical relevance and performance. We prove the convergence of the CL paradigm when used in the FBDPC‐Q algorithm. We show via simulations that the CL paradigm outperforms the IL paradigm in terms of the aggregate femtocell capacity, especially in networks with large number of femtocells and large number of power levels. In addition, we propose WCL to address the CL limitations. Finally, we evaluate the robustness and scalability of both FBDPC‐Q and SBDPC‐Q, against several typical dynamics of plausible wireless scenarios (fading, path loss, random activity of femtocells, etc.). We show that the CL paradigm is the most scalable to large number of femtocells and robust to the network dynamics compared with the IL and WCL paradigms. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
56.
Production of lipid from depolymerised lignocellulose using the biocontrol yeast,Rhodotorula minuta: The fatty acid profile remains stable irrespective of environmental conditions 下载免费PDF全文
57.
Being polar and compatible with poly(vinyl chloride), epoxidized natural rubber (ENR) is similar in behaviour to acrylonitrile butadiene rubber (NBR). To assess the extent of this similarity, the mechanical properties of 50/50 blends of PVC with these two rubbers were compared. Their response to thermo-oxidative ageing in the presence of an antioxidant and a base was also investigated by ageing the blends at 100°C for 7 days. Studies involving mechanical properties and FTIR were used to evaluate the extent of thermal degradation. The results revealed that blends of ENR show mechanical properties which are as good as, and in some instances better than, those of the NBR blends. However, the ENR blends with PVC are very prone to oxidative ageing. This might be attributed to the susceptibility of the oxirane group to ring-opening reactions, particularly in the presence of PVC, which yields HCl as it degrades. The amine-type antioxidant 2,24-trimethyl-1,2-dihydroquinoline (TMQ) improved the oxidative stability of both blends. This was more significant in the ENR blend, which in some cases attained stability comparable with that of NBR. The addition of a base, calcium stearate [Ca(St)2], did not show any influence in the PVC/ENR blend, even though it was expected to curb acid-catalysed degradation. Ca(St)2, however, improved the oxidative stability of the PVC/NBR blend. The combination of optimum amounts of TMQ and Ca(St)2 effectively improved the tensile strength of both unaged blends, without appreciable adverse effect on elongation at break. This combination also imparted stability better than that of TMQ alone. 相似文献
58.
Porcine pancreatic α-amylase digests of native and hydroxypropyl derivatives of maize, waxy maize and high amylose maize starches were subjected to ethanolic fractionation into oligosaccharide and polysaccharide fractions. Both fractions of the partial digests were analysed for blue values, reducing values, total carbohydrate, average degree of polymerisation and molar substitution (MS). Distribution of hydroxypropyl groups between the fractions varied depending on starch type and level of substitution with the polysaccharide fraction being higher in MS. Blue values (BV) and average degree of polymerisation (DP) tended to decrease with digestion while reducing (RV) increased. 相似文献
59.
Recently, organic solar cells have attracted the attention of many researchers owing to flexibility, low cost, light weight and large-area applications, and significant improvement in the power conversion efficiency (PCE). In this work, we designed chains from organic compounds as donors and replaced the core unit in each series with a variety of acceptors in order to enhance their optical and electronic characterization and performance for power conversion efficiencies in organic solar cells. We utilized density functional theory (DFT) and time-dependent density functional theory (TD-DFT) to investigate the geometry optimization by using the Gaussian 09 program. Both electronic and optical properties were determined, which involve the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) levels, the band gap energy, maximum absorption wavelength (λmax), open circuit voltage (Voc), and light harvesting efficiency (LHE). Our evaluation denotes that the small compounds suggested are predicted to exhibit the best performance compared to the first series (SC1), like a lower band gap energy, a lower HOMO energy level, a greater absorption range, and a larger PCE. 相似文献
60.
Calcium binding by both native and hydroxypropyl starches was studied in aqueous media under different pH, temperature and reaction times at various calcium: starch ratios. Calcium binding was markedly influenced by pHs and temperatures of the reaction mixture. Reaction times did not show marked influence on calcium binding. Maximum calcium binding was observed in alkaline pH and at lower temperature. Most of the calcium bound within the first 20 minutes. Thus, alkaline pH and lower temperature is more favourable for calcium binding by both native and hydroxypropyl rice starches compared to acidic pH and higher temperatures. 相似文献