Showing papers by "Zhejiang University published in 1999"

The application of chaotic oscillators to weak signal detection

Abstract: In this paper, the authors introduce a signal detection scheme based on the bifurcation behavior of the driven Duffing oscillator. Chaotic systems are sensitive to certain signals and immune to noise at the same time, the properties of which demonstrate their potential application in weak signal detection. Starting from the analysis of the intermittent chaotic motion occurring in the detecting process, they put forward a new frequency-locking principle based on the periodic characteristic of the intermittent chaos. Then, an exposition is made on how to use an array of the oscillators to detect the weak signals of unknown frequency.

Uniconazole-induced tolerance of rape plants to heat stress in relation to changes in hormonal levels, enzyme activities and lipid peroxidation

Abstract: Winter rape (Brassica napus L. cv. 601) seedlings were treated with 50 mg.l-1of foliar-applied uniconazole and then exposed to heat stress with a light/dark temperature regime of 43 °C/38 °C for 3 days at the stem elongation stage. Heat stressed plants contained lower endogenous GA3, IAA and zeatin contents than the controls, while ABA content and ethylene level were increased significantly. Uniconazole-treated plants had lower endogenous GA3 and IAA contents, and higher zeatin and ABA contents and ethylene levels. Leaf chlorophyll content and respiratory capacity of roots were reduced markedly after plants were subjected to heat stress, and foliar sprays of uniconazole retarded the degradation of chlorophyll and increased respiratory capacity of roots. Following exposure to heat, the activities of superoxide dismutase and peroxidase were significantly reduced. Uniconazole-induced heat tolerance was accompanied by increased activities of various antioxidant enzymes. Foliar applications of uniconazole reduced electrolyte leakage and malondialdehyde accumulation caused by heat stress, suggesting that uniconazole may have decreased heat-induced lipid peroxidation and membrane damage. Foliar sprays of uniconazole increased the tolerance of rape plants to heat stress.

High Efficiency Electrically-Addressable Phase-Only Spatial Light Modulator

Abstract: To realize a high efficiency electrically addressable phase-only modulator, we have coupled a liquid crystal display (LCD) to an optically addressed parallel-aligned nematic liquid crystal spatial light modulator (PAL-SLM) with a set of lenses. Phase modulation exceeding 3ϖ at 532 nm wavelength was obtained. We obtained linear transfer characteristics for phase modulation at various desired phase levels after calibration and adjustment of the transfer characteristics of the PAL-SLM and the LCD. Diffraction efficiency of 40% for binary phase grating and of 90% for 8-level blazed phase grating, which were very close to the simulation values, were observed. The power loss of the readout light was caused when passed through a half mirror, therefore, we examined a setup using an oblique readout light at the modulator. Very high diffraction efficiency was obtained from the setup by optimizing the polarization direction and optical path for this light, and the orientation of liquid crystals. Since the modulator can perform at better than 90% diffraction efficiency and at nearly 100% reflectivity, various high efficiency systems utilizing such modulators are expected.

Stochastic stabilizability and H∞ control for discrete-time jump linear systems with time delay ☆

Abstract: In this paper, the stochastic stabilizability and H∞ disturbance attenuation are studied for discrete-time linear time-delay systems that possess randomly jumping parameters using the linear matrix inequality approach. The transition of the jumping parameters is governed by a finite-state Markov process. A sufficient condition is first established on the stochastic stability using the stochastic Lyapunov functional approach. Then sufficient conditions on the existence of a stochastic stabilizing and γ-suboptimal H∞ state feedback controller are presented. It is shown that the stochastic stabilizing H∞ state feedback controller can be constructed through numerical solution of a set of coupled linear matrix inequalities. The state delay systems are first treated and extension to a class of general delay systems are then considered.

Enhanced photocatalytic activity of supported TiO2: dispersing effect of SiO2

Abstract: The physical and photocatalytic properties of the TiO 2 loaded on a unique silica using a TiO 2 sols, which was prepared by the hydrolysis of titanium n -butoxide in water (pH = 1.1) containing different alcohols and alcohol concentration, have been examined. Compared to the bare TiO 2 prepared in parallel, all the supported TiO 2 showed a higher photoactivity for the oxidation of acetophenone in water. The supported catalyst were mainly anatase crystallites of smaller size, and had a slightly higher adsorptivity toward the organic substrate. Upon the change of alcohols and alcohol concentration in the sol–gel mixture, the supported TiO 2 exhibited different response from the bare TiO 2 in the crystal structures and photoactivity. In addition, the supported TiO 2 showed a higher photoactivity on a silica of smaller particle size than on the silica of larger particles. The results suggest that the dispersion effect of silica is operative, which could be the basic role of any porous support for the TiO 2 photocatalysis.

The uptake of copper by plants dominantly growing on copper mining spoils along the Yangtze River, the People's Republic of China

Abstract: Elsholtzia haichowensis Sun, Commelina communis Linn, and Rumex acetosa Linn are the dominant species that vastly grow over the copper mining spoil heaps and copper-contaminated soil of the areas along the middle and lower streams of the Yangtze River Each has its own ecological habits Chemical analytical data show that these plants can accumulate copper to various extents, depending on the copper content of the supporting soils and plant species The highest concentration copper was found in R acetosa with the leaf copper concentration ranging from 340 to 1102 mg/kg and averaging 601 mg/kg (dry weight basis) C communis also contained high copper concentration in its leaves ranging from 19 to 587 mg/kg and averaging 157 mg/kg E haichowensis has the lowest copper concentration in its leaves from 18 to 391 mg/kg and averaging 102 mg/kg The copper content of the soils supporting all the species varies to a great extent from place to place All these lines of evidence suggest that E haichowensis, C communis, and R acetosa can serve as pioneer species for reclamation of copper mined land and can be used as model plants for investigation of plant tolerance mechanisms, and geochemical prospecting

Semi on-line scheduling on two identical machines

Abstract: This paper investigates two different semi on-line scheduling problems on a two-machine system. In the first case, we assume that all jobs have their processing times in between p and rp $(p>0, r\geq1)$ . In the second case, we assume that the largest processing time is known in advance. We show that one has a best possible algorithm with worst case ratio 4/3 while LS is still the best possible for the other problem with ratio $(r+1)/2$ which is still $3/2$ in the worst case $r=2$ .

Production of Cellulase by Solid-State Fermentation

Abstract: The advances in the production of cellulase by solid-state fermentation are reviewed. In the process description of solid-state fermentation for cellulase production, the microorganisms, raw materials for solid-state fermentation, pretreatment of raw materials, sterilization and inoculation, and solid-state fermentation process are included. The effects and control of operating conditions, such as temperature, water content and water activity, pH, aeration, and substrate, are presented. A total of eight types of bioreactors with their advantages and disadvantages for solid-state fermentation are discussed. From the engineering aspect, mathematical models for the solid-state fermentation process are also discussed and several suggestions are proposed which might further research and development of cellulase production by the solid-state fermentation process.

Simultaneous stabilization via static output feedback and state feedback

Abstract: In this paper, the simultaneous stabilization problem is considered using the matrix inequality approach. Some necessary and sufficient conditions for simultaneous stabilizability of strictly proper multi-input/multi-output (MIMO) plants via static output feedback and state feedback are obtained in the form of coupled algebraic Riccati inequalities. It is shown that any such stabilizing feedback gain is the solution of some coupled linear quadratic control problems where every cost functional has a suitable cross term. A heuristic iterative algorithm based on the linear matrix inequality technique is presented to solve the coupled matrix inequalities. The effectiveness of the approach is illustrated by numerical examples.

Molecular Marker-Assisted Dissection of Genotype × Environment Interaction for Plant Type Traits in Rice (Oryza sativa L.)

Abstract: A doubled haploid (DH) population of 123 lines from IR64/Azucena was used to analyze the genotype × environment (GE) interaction for eight plant type traits in rice (Oryza sativa L.). The total genetic effects were partitioned into genetic main effects and GE interaction effects. These two kinds of predicted effects were used in mapping quantitative trait loci (QTLs). Four to nine QTLs affecting different plant type traits were detected. Results indicated that all common QTLs detected in both environments were controlled by genetic main effects and some also by GE interaction effects. Some genomic regions identified significant QTL in only one environment; some also showed genetic main effects. Those QTLs with genetic main effects could be used in marker-assisted selection across environments. For some other map regions, QTLs were controlled by only GE interaction effects without genetic main effects. Those QTLs could be induded in marker-assisted selection only for specific environments. In most cases, the pairs of traits with a high genetic correlation shared more common QTL regions than those pairs of traits with a lower genetic correlation.

Fundamental solution for a penny-shaped crack in apiezoelectric medium

Abstract: This paper intends to present a general three-dimensional analysis of a penny-shapedcrack subjected to normal mechanical loads and free surface electric charges symmetricallyapplied on its upper and lower surfaces. To this end, the potential theory method is employed andgeneralized to analyze the piezoelectric crack problem under consideration. In particular, anotherpotential of a simple layer, corresponding to the electric effect, is introduced. As a typicalexample, a closed-form solution is first obtained for a penny-shaped crack subjected to a pair ofconcentrated forces acting in opposite directions and a pair of point charges on crack surfaces.Exact expressions for stress and electric displacement intensity factors are also presented.

Redox behaviour and catalytic properties of Ce0.5Zr0.5O2-supported palladium catalysts

Abstract: Ce 0.5 Zr 0.5 O 2 -supported palladium catalysts were prepared and used for CO and methane oxidation. The redox behaviour of these catalysts was investigated by using H 2 -TPR and CO-TPR. The shape and temperature of TPR peaks depend on the nature of reducing agent. Two peaks (α 1 and γ) were observed when H 2 was used as reducing agent for the fresh catalyst, while three peaks (α′, β′ and γ′) were observed when CO was used as a reducing agent. The addition of a noble metal effectively promotes the reduction of Ce 0.5 Zr 0.5 O 2 support, which is attributed to hydrogen spillover. After re-oxidation treatments, the PdO reduction process splits into two peaks (α 1 and α 2 ). On the basis of the catalytic activity and CO-TPR results, the activity of CO oxidation is related to the finely dispersed PdO, while the activity of methane oxidation is related to the large PdO particles.

Kinetics and mechanism of the hydrolysis of imidacloprid

Abstract: The kinetics of the hydrolysis of imidacloprid were studied at different pH values and under various temperatures. Imidacloprid was found to be stable in acidic and neutral water, but readily hydrolysed in alkaline water. The main hydrolysis product was found to be 1-[(6-chloro-3-pyridinyl)methyl]-2-imidazolidone, and a mechanism for its formation is proposed.

Alleviation of Waterlogging Damage in Winter Rape by Uniconazole Application: Effects on Enzyme Activity, Lipid Peroxidation, and Membrane Integrity.

Abstract: Oilseed rape (Brassica napus L.) seedlings treated with uniconazole [(E)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-l-yl)-l-penten-3-ol] were transplanted at the five-leaf stage into specially designed experimental containers and then exposed to waterlogging for 3 weeks. After waterlogging stress, uniconazole-treated seedlings had significantly higher activities of superoxide dismutase, catalase, and peroxidase enzymes and endogenous free proline content at both the seedling and flowering stages. Uniconazole plus waterlogging-treated plants had a significantly higher content of unsaturated fatty acids than the waterlogged plants. There was a parallel increase in the lipid peroxidation level and electrolyte leakage rate from the leaves of waterlogged plants. Leaves from uniconazole plus waterlogging-treated plants had a significantly lower lipid peroxidation level and electrolyte leakage rate compared with waterlogged plants at both the seedling and flowering stages. Pretreatment of seedlings with uniconazole could effectively delay stress-induced degradation of chlorophyll and reduction of root oxidizability. Uniconazole did not alter the soluble sugar content of leaves and stems, after waterlogging of seedlings. Uniconazole improved waterlogged plant performance and increased seed yield, possibly because of improved antioxidation defense mechanisms, and it retarded lipid peroxidation and membrane deterioration of plants.

Thermoplastic starch/PVAl compounds: Preparation, processing, and properties

Abstract: As a renewable and native polymeric material, thermoplastic starch is gaining increased acceptance because of resource and environment concerns. This study reports the formulation design of native starch/polyvinyl alcohol (PVAl) compounds; the preparation technology to make them available for thermoplastic processing; and their rheological, mechanical, and degradation properties. Among various plasticizers investigated, a mixture of glycerin and water (50/50 wt %) is found to be the best one for the compounds in terms of rheological behavior, mechanical properties, and environmental stability. The mechanical properties do not increase with the PVAl content to an expected extent, mainly due to the poor interface adhesion between the fibrous PVAl structure and the starch matrix. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2667–2673, 1999

Dielectric and ultrasonic anomalies at 16, 37, and 65 K in SrTiO 3

Abstract: In this paper we report coincident anomalies in both dielectric response and sound velocities in strontium titanate around three temperatures 16, 37, and 65 K. The anomalies occur in both single-crystal specimens and ceramics, so they cannot be related to grain boundary mechanisms, but they are enhanced by bismuth doping. The results indicate that the dielectric and ultrasonic anomalies are dynamic and not static. The physical nature of the anomalies was briefly discussed.

Dielectric Characteristics of Ceramics in BaO–Nd2O3–TiO2–Ta2O5 System

Abstract: Dielectric ceramics in the BaO–Nd 2 O 3 –TiO 2 –Ta 2 O 5 system were prepared and characterized. The ceramics with tungsten–bronze structure based on the compositions Ba 2 NdTi 2 Ta 3 O 15 and Ba 5 NdTi 3 Ta 7 O 30 had a high dielectric constant (>100) with a lower frequency-dependency when complete densification was achieved; a low dielectric loss was obtained in the former.

Genetic control of paste viscosity characteristics in indica rice (Oryza sativa L.)

Abstract: Paste viscosity parameters play an important role in estimating the eating, cooking and processing quality of rice. Four cytoplasmic male-sterile (CMS) lines and eight restorer (R) lines were employed in an incomplete diallel cross to analyze seed effects, cytoplasmic effects and maternal gene effects on the viscosity profiles of indica rice. The results indicated that the viscosity profiles of rice were controlled by the direct effects of the seed, by the cytoplasm and by maternal plant. The seed-direct effects (V A +V D ) accounted for over 51% of the total genetic variances (V A +V D +V C +V Am +V Dm ) for all the traits, suggesting that seed direct effects were more important than maternal effects and cytoplasmic effects. The additive variances (V A +V Am ) were much larger than the dominance variances (V D +V Dm ), which revealed that additive genetic effects were the major contributors of genetic variation for the paste viscosity profiles, and that selection could be applied for viscosity traits in the early generations. Significant cytoplasmic variance (V C ) was detected for hot paste viscosity (HPV), cool paste viscosity (CPV) and consistency viscosity (CSV). The cytoplasmic effects for these three traits can, therefore, not be neglected in rice breeding. It was also shown that seed heritabilities (h 2 o ) tended to be larger than maternal heritabilities (h 2 m ) and cytoplasmic heritabilities (h 2 c ). Prediction of the main genetic effects for 12 parents showed that CMS lines had highly positive effects on all the traits except for the breakdown viscosity (BDV), and that R lines had both positive and negative effects on the paste viscosity characteristics.