Wyniki wyszukiwania - Biblioteka Nauki

1

Nonlocal impulsive problems for fractional differential equations with time-varying generating operators in Banach spaces

100%

Wang J. , Yang Y. , Wei W.

Opuscula Mathematica

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2010

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tom Vol. 30, no. 3

361-381

EN

In this paper, we study the existence and uniqueness of the PC-mild solution for a class of impulsive fractional differential equations with time-varying generating operators and nonlocal conditions. By means of the generalized Ascoli-Arzela Theorem given by us and the fixed point theorem, some existence and uniqueness results are obtained. Finally, an example is given to illustrate the theory.

2

On some impulsive fractional differential equations in Banach spaces

100%

Wang J. , Wei W. , Yang Y.

Opuscula Mathematica

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2010

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tom Vol. 30, no. 4

507-525

EN

This paper deals with some impulsive fractional differential equations in Banach spaces. Utilizing the Leray-Schauder fixed point theorem and the impulsive nonlinear singular version of the Gronwall inequality, the existence of PC-mild solutions for some fractional differential equations with impulses are obtained under some easily checked conditions. At last, an example is given for demonstration.

3

Fractional nonlocal integrodifferential equations of mixed type with time-varying generating operators and optimal control

100%

Wang J. , Wei W. , Yang Y.

Opuscula Mathematica

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2010

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tom Vol. 30, no. 2

217-234

EN

In this paper, a class of fractional integrodifferential equations of mixed type with time-varying generating operators and nonlocal conditions is considered. Using a contraction mapping principle and Krasnoselskii's fixed point theorem via Gronwall's inequailty, the existence and uniqueness of mild solution are given. The existence of optimal pairs of systems governed by fractional integrodifferential equations of mixed type with time-varying generating operators and nonlocal conditions is also presented.

4

Effects of agricultural land use change on fungal community composition

100%

Wu M. , Zhong G. , Meng D. , Wei W.

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2015

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tom 63

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nr 3

EN

Anthropogenic disturbances, such as tillage, management practices, and fertilization, can influence soil microbial communities, but little is known about the effects of land use type on soil fungal communities. In this study, fungal abundance, diversity and community composition in soils were analyzed, to determine the impacts of different agricultural land use types, including old rice paddies (ORP), the long-term and (LTV), short-term (STV) cultivation of vegetables and Magnolia nursery plantations (MNP). Compared to the soils in ORP, the fungal abundance, determined by real-time quantitative polymerase chain reaction, was significantly higher in soils from LTV fields and lower in those from MNP; the copy numbers of the fungal ITS genes in the LTV soils were 30 times greater than in the MNP soils. The terminal restriction fragment length polymorphism (T-RFLP) results showed that the fungal community composition was obviously different in the different soils, based on land use type. Only three T-RFs were found in the soils from the LTV fields, followed by seven in the STV soils and nine in the MNP soils; the most (11) T-RFs were found in the ORP soils. Of the measured soil chemical properties, SOC, available P and NO₃⁻-N were the dominant factors that influenced the fungal communities based on the canonical correspondence analysis (CCA). The present study showed that conversion from paddy soil to vegetable cultivation changed soil properties, decreased soil fungal diversity, increased fungal abundance, and shifted fungal community composition.

5

Existence and uniqueness results for fractional differential equations with boundary value conditions

100%

Lv L. , Wang J. , Wei W.

Opuscula Mathematica

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2011

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tom Vol. 31, no. 4

629-643

EN

In this paper, we study the existence and uniqueness of fractional differential equations with boundary value conditions. A new generalized singular type Gronwall inequality is given to obtain important a priori bounds. Existence and uniqueness results of solutions are established by virtue of fractional calculus and fixed point method under some weak conditions. An example is given to illustrate the results.

6

On controllability for fractional differential inclusions in Banach spaces

100%

Wang J. , Li X. , Wei W.

Opuscula Mathematica

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2012

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tom Vol. 32, no. 2

341-356

EN

In this paper, we investigate the controllability for systems governed by fractional differential inclusions in Banach spaces. The techniques rely on fractional calculus, multivalue mapping on a bounded set and Bohnenblust-Karlin's fixed point theorem.

7

Roles of ecosystems in greenhouse gas emission and haze reduction in China

100%

Niu X. , Wang B. , Wei W.

Polish Journal of Environmental Studies

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2017

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tom 26

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nr 3

EN

The haze satellite map produced by NASA in 2013 showed a "Gray Great Wall" in the sky from Beijing to Hong Kong, indicating serious air pollution in China. The air pollutants and greenhouse gases can be reduced through engineering measures known as industrial gas emission and haze reduction (GGE&H reduction), as well as through green GGE&H reduction by ecosystems such as forests and wetlands that play significant roles in carbon sequestration and atmospheric environmental purification of air, soil, and water. Compared with the industrial GGE&H reduction, the green GGE&H reduction is lower in investment and operational cost, but offers more ecological benefits and therefore is more economically feasible. In this review the roles of green GGE&H reduction are summarized and its future potential is highlighted. The possible approaches to enhance the capability of green GGE&H reduction in China are discussed.

8

Reliability analysis and optimization of equal load-sharing k-out-of-n phased-mission systems

100%

Jiakai C. , Yan H. , Wei W.

Eksploatacja i Niezawodność

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2015

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tom Vol. 17, no. 2

250--259

EN

There are many studies on k-out-of-n systems, load-sharing systems (LSS) and phased-mission systems (PMS); however, little attention has been given to load-sharing k-out-of-n systems with phased-mission requirements. This paper considers equal loadsharing k-out-of-n phased-mission systems with identical components. A method is proposed for the phased-mission reliability analysis of the studied systems based on the applicable failure path (AFP). A modified universal generating function (UGF) is used in the AFP-searching algorithm because of its efficiency. The tampered failure rate load-sharing model for the exactly k-out-of-n: F system is introduced and integrated into the method. With the TFR model, the systems with arbitrary load-dependent component failure distributions can be analyzed. According to the time and space complexity analysis, this method is particularly suitable for systems with small k-values. Two applications of the method are introduced in this paper. 1) A genetic algorithm (GA) based on the method is presented to solve the operational scheduling problem of systems with independent submissions. Two theorems are provided to solve the problem under some special conditions. 2) The method is used to select the optimal number of components to make the system reliable and robust.

PL

Istnieje wiele badań na temat systemów typu „k z n”, systemów z podziałem obciążenia (load-sharing systems, LSS) oraz systemów fazowych (tj. systemów o zadaniach okresowych) (phased-missionsystems, PMS); jak dotąd mało uwagi poświęcono jednak systemom typu „k z n” z podziałem obciążenia wymagającym realizacji różnych zadań w różnych przedziałach czasowych. Niniejszy artykuł omawia systemy fazowe typu „k z n” o równym podziale obciążenia przypadającego na identyczne elementy składowe. Zaproponowano metodę analizy niezawodności badanych systemów w poszczególnych fazach ich eksploatacji opartą na pojęciu właściwej ścieżki uszkodzeń (applicablefailurepath, AFP). W algorytmie wyszukującym AFP zastosowano zmodyfikowaną uniwersalną funkcję tworzącą (universal generating function, UGF), która cechuje się dużą wydajnością. Wprowadzono model manipulowanej intensywności uszkodzeń (tamperedfailurerate, TFR) elementów o równym podziale obciążenia dla systemu, w którym liczba uszkodzeń wynosi dokładnie k z n. Model ten włączono do proponowanej metody analizy niezawodności. Przy pomocy modelu TFR można analizować systemy o dowolnych rozkładach uszkodzeń części składowych, gdzie uszkodzenia są zależne od obciążenia. Zgodnie z analizą złożoności czasowej i przestrzennej, metoda ta jest szczególnie przydatna do modelowania układów o małych wartościach k. W pracy przedstawiono dwa zastosowania metody. 1) oparty o omawianą metodę algorytm genetyczny (GA) do rozwiązywania problemu harmonogramowania prac w systemach z niezależnymi podzadaniami. Sformułowano dwa twierdzenia pozwalające na rozwiązanie problemu w pewnych szczególnych warunkach. 2) Wybór optymalnej liczby elementów składowych pozwalającej na zachowanie niezawodności i odporności systemu.

9

Structural Feature-Based Image Hashing and Similarity Metric for Tampering Detection

100%

Tang Z. , Wang S. , Zhang X. , Wei W.

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2011

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tom Vol. 106, nr 1

75-91

EN

Structural image features are exploited to construct perceptual image hashes in this work. The image is first preprocessed and divided into overlapped blocks. Correlation between each image block and a reference pattern is calculated. The intermediate hash is obtained from the correlation coefficients. These coefficients are finally mapped to the interval [0, 100], and scrambled to generate the hash sequence. A key component of the hashingmethod is a specially defined similarity metric to measure the "distance" between hashes. This similarity metric is sensitive to visually unacceptable alterations in small regions of the image, enabling the detection of small area tampering in the image. The hash is robust against content-preserving processing such as JPEG compression, moderate noise contamination, watermark embedding, re-scaling, brightness and contrast adjustment, and low-pass filtering. It has very low collision probability. Experiments are conducted to show performance of the proposed method.

10

An analytical model of the power spatial distribution for underwater optical wireless communication

100%

Wei W. , Xiao-Hui Z. , Yue-Yun C. , Xue-Jun Z.

Optica Applicata

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2012

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tom Vol. 42, nr 1

157--166

EN

Employing optical propagation theory in Hankel transform, an analytical model of the optical power spatial distribution is derived for the ideal point optical source and the Gaussian laser, respectively. Experimental measurements of the spatial distribution of a Gaussian laser are presented. The expected results of our analytical model are in good agreement with experimental data.

11

A Single-stage LED Driver for The Street Lighting System

100%

Yijie W. , Wei W. , Dianguo X.

Przegląd Elektrotechniczny

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2012

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tom R. 88, nr 1b

250-254

EN

A single-stage LED driver for the street lighting is proposed. The system consists of a constant current circuit and a constant voltage circuit, and the constant voltage circuit is gotten by integrating a buck-boost circuit and a flyback circuit.The peak current control mode is adopted in the constant current circuit which is a boost circuit and works in PWM mode. The theoretical analysis and design procedures of the proposed lighting system are proposed and discussed in detail in the paper.

PL

Opisano system świateł LED stosowanych do oświetlenia ulic. System składa się z przetwornicy buck-boost pracującej w trybie PWM.

12

Local warming about 1,3°C in alpine meadow has no effect on root vole (Microtus oeconomus L.) population during winter

100%

Sun P. , Zhao X. , Klein J. A. , Wei W.

Polish Journal of Ecology

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2005

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tom Vol. 53, nr 1

123-127

EN

The influence of air and soil warming on root vole (Microtus oeconomicus L.) population was studied in winter period in top open chambers (OTC) (0,8-1,8 m2) warmed byy conical fiberglass material and situated in alpine meadow (33250 m) at Quinghai-Tibet Plateau, China. The OTCs were distributed on an area of 30x30 m of experimental warming site; another site of the same area was a control one. The root vole population was investigated on two pairs of sites in "low-grazing" (by sheep) parts of the meadow; mark-recapture method was used. The winter-season averaged air and soil temperature inside of the chambers were 1.3°C higher than the temperature outside the chambers. The warming in the chambers had no statistically significant effect on root vole numbers, on average body mass of individual, and on average body mass of males and females. In conclusion, as small as 1.33°C warming of soil and air introduced locally and on small (several m2) scale, in the alpine meadow habitat in winter period, has possibly no effect on root vole numbers and biomass.

13

Local warming about 1.3 degree Celsius in alpine meadow has no effect on root vole [Microtus oeconomus L.] population during winter

100%

Sun P. , Zhao X. , Klein J. A. , Wei W.

Polish Journal of Ecology

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2005

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tom 53

|

nr 1

EN

The influence of air and soil warming on root vole (Microtus oeconomus L.) population was studied in winter period in top open chambers (OTC) (0.8–1.8 m²) warmed by conical fiberglass material and situated in alpine meadow (3250 m) at Qinghai-Tibet Plateau, China. The OTCs were distributed on an area of 30 × 30 m of experimental warming site; another site of the same area was a control one. The root vole population was investigated on two pairs of sites in “low-grazing” and “high-grazing” (by sheep) parts of the meadow; mark-recapture method was used. The winter-season averaged air and soil temperature inside of the chambers were 1.3°C higher than the temperature outside the chambers. The warming in the chambers had no statistically significant effect on root vole numbers, on average body mass of individual, and on average body mass of males and females. In conclusion, as small as 1.3°C warming of soil and air introduced locally and on small (several m²) scale, in the alpine meadow habitat in winter period, has possibly no effect on root vole numbers and biomass.

14

Spatial temporal analysis of land use change in the Shiyang River Basin in arid China, 1986-2015

88%

Wei W. , Xie Y. , Shi P. , Zhou J. , Li C.

Polish Journal of Environmental Studies

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2017

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tom 26

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nr 4

EN

The Shiyang River Basin has been regarded as an important ecological protective area in the Hexi corridor in northwest China. Landsat TM, ETM+, and OLI images in 1986, 2000, 2006, and 2015 were selected as basic data resources, and the circle layers and fan-shaped analysis were applied to extract change information and the characteristics of land use pattern change by a set of transfer and dynamic models. Results showed that urban and residential land expanded 176.7 km², which was about 48.57% in the past 30 years, and that the woodland and grassland decreased 7.24% and 1.39%, respectively. It was found that woodland mainly distributed in the range of elevation from 2,500 to 4,000 m, and unused land was distributed in the downstream plain, which was an average elevation of 1,500 meters below. Moreover, the area and spatial distribution of land use were influenced by human activities and resulted in fundamental changes of pattern. We found that spatiotemporal pattern analysis of land use cover was essential for understanding the structure and characteristics of urbanization and the local eco-environment.

15

Transcriptome analysis of the germinated seeds identifies low-temperature responsive genes involved in germination process in Ricinus communis

75%

Wang X. , Wang L. , Yan X. , Wang L. , Tan M. , Geng X. , Wei W.

Acta Physiologiae Plantarum

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2016

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tom 38

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nr 01

16

Serum metabolomic investigations of mulberry leaf powder supplementation in Chinese Erhualian pigs

75%

Deng S. , Li D. , Liu X. , Cai Z. , Wei W. , Chen J. , Zhang L.

Journal of Animal and Feed Sciences

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2020

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tom 29

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nr 2

17

Global gene expression responses to waterlogging in roots of sesame (Sesamum indicum L.)

75%

Wang L. , Zhang Y. , Qi X. , Li D. , Wei W. , Zhang X.

Acta Physiologiae Plantarum

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2012

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tom 34

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nr 6

EN

Waterlogging stress lowers yields in sesame (Sesamum indicum L.). A major component of waterlogging stress is the lack of oxygen available to submerged tissues. Although the morphology and physiology of plants grown under anaerobic conditions have been studied in detail, limited work has been done to elucidate adaptations at the molecular level. To gain comprehensive insight into how sesame responds to hypoxia at the genome level, we performed gene expression profiling at two time points during a 36-h period following hypoxic treatment using a whole-genome RNA-Seq analysis. We identified sets of significantly positively and negatively expressed genes (induced and repressed, respectively) in response to hypoxia with distinct temporal profiles. The genes that were affected were associated with glycolysis, nitrogen metabolism, starch and sucrose metabolism and plant hormone signal transduction and indicated the upregulation of particular pathways (glycolysis/glycogenesis) in the Kyoto Encyclopedia of Genes and Genomes. Moreover, significant changes in the expression of genes were found for pathways, including flavone and flavonol biosynthesis, steroid biosynthesis, photosynthesis, cysteine and methionine metabolism, glutathione metabolism, as well as phenylpropanoid biosynthesis, spliceosome, circadian rhythm. This study helps in elucidating the molecular mechanisms of waterlogging tolerance and provides a basis for the genetic engineering of sesame.

18

Indexing accuracy reliability sensitivity analysis of power tool tur ret

75%

Changyou L. , Wei W. , Yimin Z. , Song G. , Zhenyuan L. , Changshuai Q.

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tom Vol. 17, no. 1

27--34

EN

Power tool turret (PTT) is one of the most key parts of CNC (Computer Numerical Control) turning center and CNC turning and milling machining center. Therefore, it is very important for improving these two types of machine tools’ reliability to explore the indexing accuracy reliability of PTT and its sensitivity. To analyze the indexing accuracy reliability sensitivity of PTT, the angular displacement error of the rotating gear disc is discussed based on the measurement uncertainty theory. The tooth thickness wear process of the fixed gear disc, the rotating gear disc and the lock gear disc are modeled using Gamma process of which the parameters are estimated. The indexing error of PTT is formulated by employing the BP neural network and validated by the experiment data. Then, the indexing accuracy reliability equation of PTT is derived and its sensitivity to the mean and the standard deviation of random variables or wear stochastic processes is analyzed. The results show that the presented indexing accuracy reliability and its sensitivity of PTT are effective.

PL

Głowica narzędziowa z napędzanymi narzędziami (ang. power tool turret, PTT) stanowi jedną z kluczowych części sterowanych komputerowo tokarskich i tokarsko-frezarskich centrów obróbczych CNC. Dlatego też dla poprawy niezawodności tych dwóch rodzajów obrabiarek istotne jest badanie niezawodności w zakresie dokładności indeksowania głowicy PTT oraz wrażliwości wskaźnika niezawodności. Dla celów analizy wrażliwości wskaźnika niezawodności w zakresie dokładności indeksowania głowicy PTT, omówiono błąd przesunięcia kątowego obrotowej tarczy narzędziowej w oparciu o teorię niepewności pomiaru. Proces zużycia ściernego zębów tarcz narzędziowych: stałej, obrotowej oraz uchwytowej, zamodelowano przy użyciu procesu Gamma o szacunkowych parametrach. Błąd indeksowania PTT obliczono przy zastosowaniu sieci neuronowej BP i zweryfikowano na podstawie danych doświadczalnych. Następnie wyprowadzono równanie niezawodności w zakresie dokładności indeksowania PTT oraz przeprowadzono analizę wrażliwości wskaźnika niezawodności na średnią i odchylenie standardowe zmiennych losowych lub procesów stochastycznych zużycia. Wyniki pokazały skuteczność omawianej analizy niezawodności w zakresie dokładności indeksowania PTT oraz wrażliwości wskaźnika niezawodności.

19

Properties comparison of GaN epilayers deposited under different growth temperatures

75%

Wang P. , Yan H. , Cao B. , Wei W. , Gan Z. , Liu Z.

Opto-Electronics Review

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2011

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tom Vol. 19, No. 1

30-33

EN

Undoped GaN epilayers were grown on c-plane sapphire substrates under different growth temperatures by metalorganic chemical vapour deposition (MOCVD). The optical and structural characteristics of these grown samples were studied and compared. It was found that the crystalline quality of GaN film deposited at 1050°C was better that of other samples. Photoluminescence spectra showed that the intensities of yellow luminescence band of the samples decreased as the growth temperature increased. All above test results demonstrate that high temperature deposition can serve as a good method for high-quality GaN epilayer growth and there exists an optimal growth temperature.

20

Linkage disequilibrium and functional analysis of PRE1 insertion together with SNPs in the promoter region of IGFBP7 gene in different pig breeds

63%

Wu Q. , Yu H. , Wei W. , Cheng Y. , Huang S. , Shi H. , Liu S. , Xia J. , Jia H. , Hao L.

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2018

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tom 59

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nr 2