Wyniki wyszukiwania - BazTech

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Allometric Partitioning Theory Versus Optimal Partitioning Theory : The Adjustment of Biomass Allocation and Internal C-N Balance to Shading and Nitrogen Addition in Fritillaria unibracteata (Liliaceae)

Guo H., Xu B., Wu Y., Shi F., Wu C., Wu N.

Polish Journal of Ecology

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2016

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Vol. 64, nr 2

189--199

EN

Fritillaria unibracteata is a classic perennial alpine herb. In this study, we examined it's responses to shading (SH) and nitrogen addition (NA), as well as its correlation with internal C-N balance to detect how it adjusted to the changes of habitat conditions. Randomized block experiment was carried out in the field in Chuanbeimu Research Station in Songpan County, Sichuan Province, China (32°09′54″N, 103°38′36″E, altitude 3300 m a.s.l.). Two growing seasons after NA and SH, Fritillaria unibracteata's total plant biomass decreased significantly, with the proportion of biomass allocated to aboveground significantly increased. In addition, in this study, under both SH and NA treatments, Fritillaria unibracteata increased its biomass allocation to above-ground, which consisted with optimal partitioning theory. Moreover, Fritillaria unibracteata's biomass allocation was significantly correlated with its internal C-N status, regardless of nitrogen and light condition. We conclude that Fritillaria unibracteata optimizes its biomass allocation between root and shoot by adjusting its internal C-N balance, which would not be changed by the specialized resource storage organ-bulb.

2

A novel approach to photonic generation of periodic triangular radio frequency waveforms

Xiang P., Guo H., Chen D., Zhu H., Wu C.

Optica Applicata

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2015

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Vol. 45, nr 3

381--391

EN

A novel approach to photonic generation of triangular radio frequency waveforms with a tunable repetition rate is proposed and analyzed. In the proposed system, a continuous-wave light is modulated by a reference microwave signal through a polarization modulator, and then its output optical sidebands are manipulated by a microwave photonic filter with a negative tap. By properly adjusting the system parameters, full-duty-cycle triangular radio frequency waveforms can be generated after optical-to-electrical conversion, and its repetition rate (frequency) can be tuned in a wide range. A model describing the proposed system is derived, which is verified via computer simulations.

3

Simultaneous state and parameter estimation based actuator fault detection and diagnosis for an unmanned helicopter

Wu C., Qi J., Song D., Qi X., Han J.

International Journal of Applied Mathematics and Computer Science

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2015

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Vol. 25, no. 1

175--187

EN

Simultaneous state and parameter estimation based actuator fault detection and diagnosis (FDD) for single-rotor unmanned helicopters (UHs) is investigated in this paper. A literature review of actuator FDD for UHs is given firstly. Based on actuator healthy coefficients (AHCs), which are introduced to represent actuator faults, a combined dynamic model is established with the augmented state containing both the flight state and AHCs. Then the actuator fault detection and diagnosis problem is transformed into a general nonlinear estimation one: given control inputs and the measured flight state contaminated by measurement noises, estimate both the flight state and AHCs recursively in each time-step, which is also known as the simultaneous state and parameter estimation problem. The estimated AHCs can further be used for fault tolerant control (FTC). Based on the existing widely used nonlinear estimation methods such as the unscented Kalman filter (UKF) and the extended set-membership filter (ESMF), three kinds of adaptive schemes (KF-UKF, MIT-UKF and MIT-ESMF) are proposed by our team to improve the actuator FDD performance. A comprehensive comparative study on these different estimation methods is given in detail to illustrate their advantages and disadvantages when applied to unmanned helicopter actuator FDD.

4

Higher Order Nonlinearity of Niho Functions

Sun G., Wu C.

Fundamenta Informaticae

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2015

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Vol. 137, nr 3

403--412

EN

The r-th order nonlinearity of Boolean functions is an important cryptographic criterion associated with some attacks on stream and block ciphers. It is also very useful in coding theory, since it is related to the covering radii of Reed-Muller codes. In this paper we investigate the lower bound of the higher-order nonlinearity of Niho Boolean functions f(x) = tr(λxd) over F2n, where... [formula]

5

Luminescence of hydrothermally fabricated PbF2:Er3+ particles and their application in bifacial silicon solar cells

Yang F, Wu C., Hao X, Chen Y., Lu J., Yang Sh.

Optica Applicata

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2014

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Vol. 44, nr 3

463--473

EN

We report the synthesis of PbF2:Er3+ particles using a hydrothermal method. The structure and upconversion emission properties of the products are investigated by scanning electron microscopy, X-ray diffractometer, Raman spectrophotometer and fluorescence spectrometry. An increase in Er3+ concentration in the crystals changes the PbF2 structure from a mixed phase to a cubic phase and decreases the grain size to nanoscale levels. Enhanced upconversion efficiency is achieved after annealing resulted from the formation of the cubic phase and the increase of grain size. The optimal Er3+ concentration is found to be 4% after annealing, and applied to the back of a bifacial silicon solar cell, maximum external quantum efficiencies of 0.38% and 0.79% are respectively obtained under 0.77 W/cm2 laser excitation (1560 nm) and AM1.5 + laser co-excitation.

6

On the space of (s)-integrable functions for a monotonic measure

Wu C., Ren X., Wu C.

Commentationes Mathematicae

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2013

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Vol. 53, No. 2

135--145

EN

In this paper we introduce and study the space of real-valued (s)-integrable functions for a monotonic measure, and consider some relations between this space and the space of real-valued measurable functions.

7

Peng G., Wu C., Xu X., Yang D.

Polish Journal of Ecology

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2012

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Vol. 60, nr 2

311-321

EN

In woody perennials, leaf structure and biochemistry vary with tree age under changing environments. However, the related eco-physiological mechanisms have not been elucidated yet. In this study, we investigated agerelated responses of juvenile and mature subalpine fir trees (Abies faxoniana Rehder & E.H. Wilson.) growing at altitudes between 2,500 and 3,500 m in the Wanglang Natural Reserve in southwest China, to study the adaptive strategies of different age trees to suit changing environments. We found that there were distinct age- and altituderelated changes in the structural and biochemical characteristics of leaves. At all altitudes, mature trees exhibited higher area- and mass-based leaf nitrogen content (N[area], N[mass]), leaf mass per area (LMA) and stable isotope carbon composition ([delta^13]C), and a lower chlorophyll (Chl) content than those juvenile trees, except for N[mass] at 3,000 m as well as LMA at 2,750 m, where the values of N[mass] and LMA in mature trees were slightly lower than those in juvenile trees. Furthermore, leaf characteristics showed significant differences in the change rates with altitude between different age groups. Our results indicated that assimilative organs in mature trees do not suffering from nutrient deficiency and that juvenile and mature trees possess different adaptive growth strategies under changing environments, as indicated by higher leaf N content in mature trees and the opposite patterns of LMA and Chl content between two age groups. We also concluded that juvenile could be more sensitive to global warming due to a greater altitudinal influence on the leaf traits in juvenile trees than those in mature trees.

8

On a property of phi-variational modular spaces

Wang J., Wu C.

Opuscula Mathematica

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2010

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Vol. 30, no. 2

209-215

EN

Maligranda pointed out whether condition (B.1) is satisfied in the variational modular space X*ρ is an open problem. We will answer this open problem in X*ρ', a subspace of X*ρ. As a consequence this modular space X*ρ' can be F-normed.

9

Entire graphs under a general flow

Mao J., Li G., Wu C.

Demonstratio Mathematica

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2009

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Vol. 42, nr 3

631-640

EN

An initial entire graph with bounded second fundamental form in Rn+1 over some hyperplane is evolving under a general flow defined in the paper. For an additionally suitable condition in the main theorem, we obtain gradient and curvature estimates, leading to long-time existence of the flow, and convergence to an entire graph in the limit.

10

Risk forecast of spontaneous combustion of sulfide ore dump in a stope and controlling approaches of the fire

Wu C., Li Z., Yang F., Hu H., Gu D.

Archives of Mining Sciences

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2008

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Vol. 53, no 4

565-579

EN

In this paper, a set of reliable devices and flowchart used for testing the potential of spontaneous combustion of sulfide ores (SOSC) are presented. An effective assessment method which depends upon the fire index system for evaluating the risk of SOSC in amining stope is introduced. To get more detailed information on self-heating situation in the ore dump at various period, the surface temperature on the ore dump is measured by an infra image apparatus and the temperature in the ore dump is analyzed both by ANSYS and FLUENT software. These results are visual and effective for applying correct measures for preventing the fire-breeding. Also, a group of chemical agents for abating the oxidized velocity are invented and can be sprayed into the ore dump. By integrating with all technical approaches described in above and using them for dealing with various practical conditions, the risk of SOSC in a stope can be effectively controlled.

PL

W niniejszym referacie, opisane zostały niezawodne urządzenia oraz schematy działań służące do badania potencjalnego samozapalenia się rudy siarczanu (SOSC). Przedstawiona została skuteczna metoda oceny służąca oszacowaniu ryzyka SOS C w przodku, która zależy od systemu wskaźnika pożarowości. Aby uzyskać bardziej szczegółowe informacje dotyczące samoogrzewania się hałdy rudy w różnych okresach, temperatura powierzchniowa na hałdzie mierzona jest za pomocą przyrządu na podczerwień, natomiast temperatura wewnątrz hałdy analizowana jest przy użyciu oprogramowania typu ANSYS oraz FLUENT. Wyniki tych badań są widoczne i użyteczne w celu zastosowania odpowiednich środków zapobiegających powstawaniu ognia. Wynalezione również zostały środki chemiczne służące spowolnieniu procesu utleniania, które mogą zostać rozpylone po powierzchni hałdy. Połączenie oraz praktyczne wykorzystanie wszystkich wyżej opisanych metod, może zapewnić efektywne kontrolowanie ryzyka samoistnego zapalenia się rudy siarczanu w przodku.

11

Phase Behavior and Solubilization of NAPL/Water/n-Dodecyl polyglucoside/n-Butanol Microemulsion System

Chai J., Yang X., Gao Y., Wu C.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 4

547-556

EN

The phase behavior of the middle-phase microemulsion nonaqueous phase liquids (NAPLs)/water/n-dodecyl polyglucoside/n-butanol has been studied with Winsor type and - fishlike phase diagrams. The phase types, the phase volumes and the region of the middle-phase microemulsion were observed from Winsor phase diagram. From - fishlike phase diagram, the composition of the hydrophile-lipophile balanced interfacial layer was calculated. The solubilization power of the microemulsion for differentNAPLs was discussed, and the order of the solubilization power for three kinds of NAPLs is determined to be carbon tetrachloride > toluene > n-hexane.

12

Synthesis, Crystal Structure and Magnetism Study on a Two-Dimensional Cu(II) Coordination Polymer with 2,5-Dimethylpyrazine-1,4-dioxide as Bridging Ligand

Shi J., Zhang X., Wu C., Liu L.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 12

2063-2068