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191.
This paper describes the robust control system design for a ship dynamic positioning system. The control design is based on an approximate linear model derived from the nonlinear hydrodynamic equations governing the horizontal motions of the ship. The nonlinear models of the ship, seawaves, current, wind and thrusters are derived and simulated for control design verification. The H control design technique is employed to design the controller. The control problem is formulated in state‐space form and the design specifications are translated into requirements on the weighting functions of the error signal and the thrusters input. A tuning procedure is proposed based on the wind and wave disturbances. The controller is initially tested on the nonlinear ship model and simulation results are presented to demonstrate the robustness of the H controller. Tank tests results are then presented to assess the controller performance. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
192.
Male Sprague-Dawley rats four weeks or eight months of age were fed purified diets containing 10% fat, either as a blend of safflower oil and palm olein (polyunsaturated fatty acids, PUFA, 34%), a blend of linseed oil and palm olein (PUFA, 33%) or sardine oil (PUFA, 33%) for four weeks. In other trials, sterol contents were made equivalent by supplementing cholesterol to a blend of corn oil and palm olein (PUFA, 30%) or phytosterol to sardine oil (PUFA, 30%). Fish oil was hypolipidemic in rats of different ages, but it tended to increase liver cholesterol in adult animals and this was not improved by the addition of phytosterol. The age-dependent increase in liver cholesterol was not duplicated in rats fed a vegetable fat blend supplemented with cholesterol. At both ages, liver 3-hydroxy-3-methylglutaryl coenzyme A reductase activity was lower in the sardine oil than in the other groups. There were no significant age- or diet-related differences in the activity of liver cholesterol 7α-hydroxylase. Fecal steroid excretion was comparable in age-matched rats fed diets supplemented either with cholesterol or phystosterol. Sardine oil reduced the Δ6-desaturase activity markedly as compared with linseed oil, and age-dependent reduction of the desaturase activity was observed in all dietary groups examined. Thus, the results showed a specific effect of fish oil on lipid metabolism.  相似文献   
193.
Eluted metals from Enshu (a Chinese) and Stratford (an Australian) coal during pretreatments with methanol/water and dilute acetic acid solutions were characterized and quantitatively analyzed by solid-state 23Na NMR, cation chromatography, X-ray fluorescence (XRF), and Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) measurements. To achieve the requirements of solvent extracted coal (namely Hyper-Coal: HPC) for its direct utilization to gas turbine system, alkali and alkali-earth metals such as Na, K, and Ca should be removed from coals. A quantitative analytical method of alkali metals with ICP-AES in combination with flow injection system is established for the evaluation of remaining alkali metal contents, especially for the quantitative analysis of Na concentration in the original coal and its HPC. Microwave irradiation acidic digestion pretreatment under controlled high pressure and temperature is very essential to the prompt and quantitative analyses of all the metals in coals and their derived HPC. Combination of ICP-AES with XRF and/or cation chromatography is also effective for the respective analyses of the residue and the extract or filtrate. Solid-state 23Na NMR spectra of the coals before and after solvent soaking pretreatment or acetic acid treatment revealed that ion-exchangeable Na species might be rather selectively eluted by these treatments. It is also suggested that the remaining Na species could not be removed by dilute acetic acid solutions.  相似文献   
194.
In our previous work, 10 Wh-class (30650 type) lithium secondary batteries, which were fabricated with LiNi0.7Co0.3O2 positive electrodes and graphite-coke hybrid carbon negative electrodes, showed an excellent cycle performance of 2350 cycles at a 70% state of charge charge-discharge cycle test. However, this cycle performance is insufficient for dispersed energy storage systems, such as home use load leveling systems. In order to clarify the capacity fade factors of the cell, we focused our investigation on the ability discharge capacity of the positive and negative electrodes after 2350 cycles. Although the cell capacity deteriorated to 70% of its initial capacity after 2350 cycles, it was confirmed that the LiNi0.7Co0.3O2 positive electrode and graphite-coke hybrid negative electrode after 2350 cycles still have sufficient ability discharge capacity of 86 and 92% of their initial capacity, respectively. Accompanied by the result for a composition analysis of the positive electrode material by inductively coupled plasma (ICP) spectroscopy and atomic absorption spectrometry (AAS), electrochemical active lithium decreased and the LixNi0.7Co0.3O2 positive electrode could be charged-discharged in a narrow range of between x=0.41 and 0.66 in the battery, although it had enough ability discharge capacity that can use between x=0.36 and 0.87. It is predicted that solid electrolyte interface formation by electrolyte decomposition on the carbon negative electrode during the charge-discharge cycle test is a main factor of the decrease of electrochemical active lithium.  相似文献   
195.
Homogeneous graft copolymerization of styrene onto cellulose was carried out using a SO2–DEA–DMSO cellulose solvent reaction medium and γ-ray mutual irradiation. The yield of grafted side chain polymer and the homopolymer in this reaction system proved to be polysulfone, a styrene–sulfur dioxide copolymer in which the number of sulfur atoms per polymer chain is 3–3.5. Several characterizations of the graft product were attempted. The graft products were extracted with boiling benzene for 24 hr to remove homopolymer, and then the cellulose backbones were hydrolyzed. After hydrolysis, the polysulfone residues were separated by thin-layer chromatography (TLC) into two components, i.e., attendant homopolysulfone and the true side chain polysulfone having some sugar residues at one of the polymer chain ends. The weight fraction of these components for each graft product was determined by a TLC scanner. The molecular weight of the side chain polysulfone remained constant and significantly lower than that of the homopolysulfone throughout the reaction period. By assuming that no scission of cellulose chains occurred throughout the graft reaction, the number of branches per starting cellulose molecule was assessed to be surprisingly large, ranging from 2.4 to 10.6 at a total dose of 1–8 mR of irradiation. It was also found that percent grafting increased with irradiation time because of an increase in the number of branches per cellulose chain. Furthermore, we succeeded in separating the graft product into ungrafted cellulose and the true graft copolymer containing a small amount of attendant hompolysulfone.  相似文献   
196.
Male Sprague-Dawley rats at the ages of four weeks and nine months were fed purified diets containing 20% proteins either as casein (CAS), milk whey protein (WHY), or soybean protein (SOY) with 5% sardine oil for four weeks. The hypocholesterolemic effect of SOY was not statistically evident as compared to milk proteins at both ages, although serum cholesterol tended to be low in the SOY groups. A significant agedependent increase in serum cholesterol was observed in all dietary groups. Liver cholesterol concentrations were comparable in young rats, whereas in adults they were significantly lower in the SOY than in the CAS or WHY groups. At both ages, the activity of liver 3-hydroxy-3-methylglutaryl coenzyme A reductase tended to be higher in the SOY than in the other groups. Fecal steroid excretion was significantly higher in rats fed SOY than those fed either CAS or WHY, especially in adult rats. Significant age- and dietary protein-effects were observed in fatty acid profiles of liver microsomal phospholipids. Thus, the effects of dietary proteins on various lipid parameters were essentially maintained even when fish oil served as the source of dietary fat.  相似文献   
197.
Recent studies have described the topologies of various networks including the Internet are categorized as scale-free networks. Scale-free network is extremely vulnerable to node attacks. However, the suitability of the topology of the Internet for communications has not been studied. We investigate whether the current Internet is optimized in both aspects of communication efficiency and attack tolerance. For this, we define three metrics to represent the capabilities of the network, which are Clustering coefficient, Efficiency, and Reachability. As a result, we found that the value of γ, a scaling exponent in power law function representing the degree distribution of a scale-free network, may be reduced in the present Internet. To reduce the value of γ, we propose four strategies for re-organizing a network. However, in real network, we cannot control the user’s preference directly. We use a diffusion model based on social behavior dynamics. Furthermore, we show the characteristics of the re-organized networks, and discuss which strategy is more appropriate for achieving a desired network.  相似文献   
198.
Small nucleolar RNAs (snoRNAs) are known that they will participate with RNA modification. However, detail functions of snoRNAs have not been clear still yet. In order to make clear functions of snoRNA, finding more snoRNAs and studying their works in cells are required. In this paper, we propose a method to detect snoRNA genes using extended-weight-updating self-organizing map (eSOM). An input vector to eSOM consists of a feature vector and a target vector. Different from a conventional SOM, a winner node for an input vector is decided by the feature vector only, and all the weights around the winner node are updated to be close to the input vector. We employ bases appearance probabilities and complementary base pair ratio for a feature vector. A target vector is a flag which is 1.0 or 0.0 for a positive or a negative sample, respectively. Experimental results showed our method achieved 91 and 93 % detection ratio for boxC/D and boxH/ACA type snoRNA genes, respectively.  相似文献   
199.
An InSb Schottky detector, fabricated from an undoped InSb wafer with Hall mobility which is higher than those of previously employed InSb wafers, was used for alpha particle detection. The output pulse of this InSb detector showed a very fast rise time, which was comparable with the output pulses of scintillation detectors.  相似文献   
200.
Seiji Nomura  Kenji Kato  Ikuo Komaki 《Fuel》2003,82(14):1775-1782
The recycling process of waste plastics using coke ovens is now being studied. The effect of plastic addition on coal caking property was investigated. It was revealed that thermal decomposition products of plastics interacted with bituminous coal during carbonization in coke ovens. The effect of plastic addition on coal caking property varied with types of plastics. The addition of aliphatic polymers such as polyethylene (PE), polypropylene (PP) and poly(vinyl chloride) (PVC) had only a small effect on coal caking property and coke strength and in some cases PE addition increased coke strength. On the other hand, the addition of polystyrene (PS), poly(ethylene terephthalate) (PET) and terephtalic acid (TFA) inhibited coal expansion and fusion, decreased maximum fluidity and total dilatation, and deteriorated the coke strength. These differences were discussed from the viewpoint of the interaction between thermal decomposition products of plastics and hydrogen in coal. It was suggested that the radical formed as a result of PS or PET thermal decomposition abstracted hydrogen from coal, which resulted in the decrease in coal caking property.  相似文献   
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