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1

Hardness identification of rock based on multi-sensor information fusion during the process of roadway tunnelling

Wang H., Lu S., Huang M., Zhao X.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2020

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Vol. 68, nr 6

1301--1309

EN

In this paper, a new dynamic model was proposed for identifying the rock hardness during the process of roadway tunnelling, thereby regulating the speed of the driving motor and the torque of the cutting head. The presented identification model establishes a multi-information feature database containing vibration signals in the y-axis, acoustic emission signals, cutting current signals, and temperature signals. Subsequently, we obtain the membership functions (MFs) of the given multiple signals with the amount of feature samples according to the principle of minimum fuzzy entropy. Furthermore, a rock hardness identification model was established based on multi-sensor information fusion and Dempster-Shafer (D-S) evidence theory. To prove the accuracy of the proposed model, an identification experiment was carried out through the cutting of a poured mixed rock specimen with five grades of hardness. As a result, the proposed identification model recognizes the rock hardness accurately for fifteen sampling points, which indicates the significance of the method with regard to the dynamic identification of rock hardness during the process of roadway tunnelling, and further provides data support for adjusting the speed of the cutting head adaptively, thereby achieving high efficiency tunnelling.

2

Zmiany składu lotnych związków zachodzące w napoju mieszanym podczas fermentacji przy zastosowaniu dostępnego w handlu szczepu drożdży

Cai W., Tang F., Shan C., Yang L., Zhan Q., Zhao X., Ning M.

Przemysł Chemiczny

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2018

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T. 97, nr 8

1398--1405

PL

Do produkcji napoju mieszanego przez kontrolowaną fermentację alkoholową z zastosowaniem dostępnych w handlu suszonych drożdży winiarskich BV818 użyto owoców z Xinjiang (jujuba, goja i winogrona). Badano zmiany składu lotnych związków zachodzące podczas przetwarzania napoju. Zidentyfikowano łącznie 104 lotne związki występujące w napojach przed i po fermentacji alkoholowej. Stężenie alkoholi i estrów podczas fermentacji alkoholowej wzrosło, podczas gdy stężenie kwasów, ketonów, aldehydów i związków heterocyklicznych zmniejszyło się. Fermentacja alkoholowa doprowadziła do wzbogacenia końcowych produktów w pożądane lotne związki.

EN

Jujube, goji and grape fruits were crushed and pressed to resp. juices fermented then by using active wine dry yeast. The juices were analyzed for chem. compn. before and after fermentation by gas chromatog. coupled with mass spectrometry. One hundred and four chem. compds. (alcs., org. acids, esters, ketones, aldehydes and heterocycles) were identified. The concns. of alcs. and esters increased and the concn. of undesirable aldehydes and ketones decreased during the alc. fermentation.

3

Theoretical and experimental investigations of the bifurcation behavior of creep groan of automotive disk brakes

Zhao X., Gräbner N., Wagner U. von

Journal of Theoretical and Applied Mechanics

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2018

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Vol. 56 nr 2

351--364

EN

There are several low frequency vibration phenomena which can be observed in automotive disk brakes. Creep groan is one of them provoking noise and structural vibrations of the car. In contrast to other vibration phenomena like brake squeal, creep groan is caused by the stick-slip-effect. A fundamental investigation of creep groan is proposed in this paper theoretically and experimentally with respect to parameter regions of the occurrence. Creep groan limit cycles are observed while performing experiments in a test rig with an idealized brake. A nonlinear model using the bristle friction law is set up in order to simulate the limit cycle of creep groan. As a result, the system shows three regions of qualitatively different behavior depending on the brake pressure and driving speed, i.e. a region with a stable equilibrium solution and a stable limit cycle, a region with only a stable equilibrium solution, and a region with only a stable limit cycle. The limit cycle can be interpreted as creep groan while the equilibrium solution is the desired vibration-free case. These three regions and the bifurcation behavior are demonstrated by the corresponding map. The experimental results are analyzed and compared with the simulation results showing good agreement. The bifurcation behavior and the corresponding map with three different regions are also confirmed by the experimental results. At the end, a similar map with the three regions is also measured at a test rig with a complete real brake.

4

Influence of the Needle Number on the Heat Insulation Performance of Pre-oxidized Fibre Felts

Zhao X., Liu Y., Liang T.

Fibres & Textiles in Eastern Europe

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2018

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Vol. 26, no. 3 (129)

80--86

EN

Many factors were needed to be considered to prepare pre-oxidised fibre felts with excellent heat insulation performance, and different production processes showed differences in the heat insulation performance of pre-oxidised fibre felts. In order to probe into the influence of the production process on the heat insulation performance of materials, a large number of experiments were needed to be carried out. For needle-punched nonwoven pre-oxidised fibre felts, web features, needle characteristics and the needle process will all affect the structure of pre-oxidised fibre felts, thus bringing a major influence on the heat insulation performance of pre-oxidised fibre felts. In this paper, the influence of the needle number on the heat insulation performance of pre-oxidised fibre felts was mainly studied. Results showed that an increase in the needle number will cause a decrease in the thickness and gram weight of pre-oxidised fibre felts, and a weakening trend in the heat insulation performance of pre-oxidiaed fibre felts with an increasing needle number at room temperature and at 100-200 °C was shown. Moreover when the needle number was 1 and 2, the pre-oxidised fibre needled felts had good heat insulation performance, and for pre-oxidized fibre felts at different needle numbers with increasing temperature, the temperature difference in a steady state increased linearly.

PL

Aby przygotować filce z włóknami preoksydowanymi o doskonałymi właściwościami izolacyjnymi, należy wziąć pod uwagę wiele czynników, a różne procesy produkcyjne wykazały różnice w wydajności izolacji cieplnej filców włóknistych. Aby zbadać wpływ procesu produkcyjnego na parametry izolacji termicznej materiałów, konieczne było przeprowadzenie wielu eksperymentów. W pracy badano głównie wpływ liczby igieł na izolacyjność cieplną wstępnie utlenionych filców włóknistych. Wyniki pokazały, że zwiększenie liczby igieł spowodowało zmniejszenie grubości i gramatury filców włóknistych oraz osłabienie tendencji w zakresie izolacji cieplnej filców z włóknami preoksydowanymi wraz ze wzrastającą liczbą igieł w temperaturze pokojowej i w 100-200 °C. Ponadto, gdy liczba igieł wynosiła 1 i 2, pre-utlenione włókniny igłowane miały dobrą izolację cieplną, a dla wstępnie utlenionych filców włóknistych przy różnych numerach igieł ze wzrastającą temperaturą, różnica temperatur w stanie ustalonym wzrastała liniowo.

5

Tracking control and robustness study of shifting process

Zhao X., Guan Ch.

Archives of Transport

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2018

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Vol. 46, iss. 2

97--104

EN

Heavy dump vehicles are usually working with big load changes and bad work environment, thus change the friction performance of transmission clutches, as well as great affect the shift quality seriously, which influence the vehicle performance. Many researchers developed a lot to design a useful automatic transmission control system. Using PID tracking control and Monte Carlo method, the controller based on an dynamic model was set up to analyze the shifting process of automatic transmission and its robustness in this paper. The shift process was divided into four stages, low-gear phase, torque phase, inertia phase and high-gear phase. The model presents the process from the first gear to the second gear when the torque has big change. Since the jerk and the friction work of clutch are both related to the speed of clutch which was easier to control, it was chose as the target to control the oil pressure for satisfying the requirement of shift quality. The simulation software, Maplesim and Simulink, were used to build the vehicle model and shifting controller for simulation under different working conditions, and the maximum jerk was changed from 34 m/s3 to 12 m/s3 after the optimization. In this paper the Monte Carlo has been used to quantize and evaluate the robustness of the closed-loop system for the friction coefficients and output torque of turbine variation leading by the friction feature parameters and throttle angle changed. Monte Carlo method was used to analyze the effectiveness and robustness of PID controller, which proves that it has good control effect when the throttle is ongoing minor fluctuations. When the throttle is full opening, a quadratic optimal controller based on disturbance is designed by the method of multi-objective optimization. When it changes within 20 percent, PID controller was designed under the guidance of tracking thoughts. The results also show that the controller could still obtain better effect when the friction coefficient ranged from -40 % to 40 % as well as engine torque changed from -20 % to 20 %, which indicates the robustness of controller.

6

Sensitivity analysis study of the source parameter uncertainty factors for predicting near-field strong ground motion

Li Z., Gao M., Jiang H., Chen X., Li T., Zhao X.

Acta Geophysica

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2018

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Vol. 66, no. 4

523--540

EN

Uncertainty factors have substantial influences on the numerical simulations of earthquakes. However, most simulation methods are deterministic and do not sufficiently consider those uncertainty factors. A good approach for predicting future destructive earthquakes that is also applied to probabilistic hazard analysis is studying those uncertainty factors, which is very significant for improving the reliability and accuracy of ground-motion predictions. In this paper, we investigated several uncertainty factors, namely the initial rupture point, stress drop, and number of sub-faults, all of which display substantial influences on ground-motion predictions, via sensitivity analysis. The associated uncertainties are derived by considering the uncertainties in the parameter values, as those uncertainties are associated with the ground motion itself. A sensitivity analysis confirms which uncertainty factors have large influences on ground motion predictions, based upon which we can allocate appropriate weights to those uncertainty factors during the prediction process. We employ the empirical Green function method as a numerical simulation tool. The effectiveness of this method has been previously validated, especially in areas with sufficient earthquake record data such as Japan, Southwest China, and Taiwan, China. Accordingly, we analyse the sensitivities of the uncertainty factors during a prediction of strong ground motion using the empirical Green function method. We consequently draw the following conclusions. (1) The stress drop has the largest influence on ground-motion predictions. The discrepancy between the maximum and minimum PGA among three different stations is very large. In addition, the PGV and PGD also change drastically. The Arias intensity increases exponentially with an increase in the stress drop ratio of two earthquakes. (2) The number of sub-faults also has a large influence on various ground-motion parameters but a small influence on the Fourier spectrum and response spectrum. (3) The initial rupture point largely influences the PGA and Arias intensity. We will accordingly pay additional attention to these uncertainty factors when we conduct ground-motion predictions in the future.

7

Diatom stratigraphy of FA-1 core, Qarun Lake, records of Holocene environmental and climatic change in Faiyum Oasis, Egypt

Zalat A. A., Marks L., Welc F., Salem A., Nitychoruk J., Chen Z., Majecka A., Szymanek M., Chodyka M., Tołoczko-Pasek A., Sun Q. L., Zhao X., Jiang J.

Studia Quaternaria

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2017

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Vol. 34, Nr 1

61--69

EN

This study evaluates changes in the environmental and climatic conditions in the Faiyum Oasis during the Holocene based on diatom analyses of the sediment FA-1 core from the southern seashore of the Qarun Lake. The studied FA-1 core was 26 m long and covered the time span ca. 9.000 cal. yrs BP. Diatom taxa were abundant and moderately to well-preserved throughout the core sediments. Planktonic taxa were most abundant than the benthic and epiphytic forms, which were very rare and sparsely distributed. The most dominant planktonic genera were Aulacoseira and Stephanodiscus followed by frequently distribution of Cyclostephanos and Cyclotella species. The stratigraphic distribution patterns of the recorded diatoms through the Holocene sediments explained five ecological diatom groups. Thesegroups represent distinctive environmental conditions, which were mainly related to climatic changes through the earlyand middle Holocene, in addition to anthropogenic activity during the late Holocene. Comparison of diatom assemblages in the studied sediment core suggests that considerable changes occurred in water level as well as salinity. There were several high stands of the freshwater lake level during humid, warmer-wet climatic phases marked by dominance of planktonic, oligohalobous and alkaliphilous diatoms alternated with lowering of the lake level and slight increases in salinity and alkalinity during warm arid conditions evident by prevalence of brackish water diatoms.

8

Comparative Effects of Aquaculture and Water Level Fluctuations on Macroinvertebrate Communities in Three Gorges Reservoir, China

Chi S., Zheng Z., Zhang Z., Hu J., Zheng J., Zhao X., Hu J., Dong F., Peng J.

Polish Journal of Ecology

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2017

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Vol. 65, nr 4

390--404

EN

In this study, the comparative effects of the two disturbances (aquaculture and water level fluctuations) on macroinvertebrate communities were explored in two waterbodies connected with the reservoir system of Three Gorges Reservoir (TGR) in China. One water body called Gaoyang Bay which suffered organic pollution from intensive aquaculture. Another named Hanfeng Lake, where the effects of water-level fluctuations are obvious. The results showed that aquaculture could significantly affect the chemical forms of nutrients, decrease the α-diversity and increase the β-diversity of macroinvertebrates although the communities in the treatment area in Gaoyang Bay were not fundamentally changed comparing to the control area in the same bay. The densities of macroinvertebrates in the treatment area were significantly lower than that of the control area. The composition of functional feeding groups in the treatment area was close to that in Hanfeng Lake, but obviously different from that in the control area in Gaoyang Bay and the collectors and predators dominated the communities in this control area with the highest percentages. Although water-level fluctuations had negative effects on the communities by decreasing the α-diversity and increasing the β-diversity, which were confirmed by the values of Simpson index, Shannon-Wiener index and Harrison's index in the control area of Gaoyang bay and Hanfeng Lake, the adverse effects were relative low compared to aquaculture. In the bays of TGR, the small-scale disturbance (aquaculture activities) had more significant negative effects compared to the big-scale disturbance (water-level fluctuations related to dam operation of TGR).

9

Research of Fluorinated Acrylate Copolymer on Flax Fabric

Sui Z., Yang K., Chen J., Zhao X., Gao S.

Fibres & Textiles in Eastern Europe

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2017

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Vol. 25, no. 6 (126)

83--88

EN

A fluorine-containing acrylate copolymer emulsion was prepared in this study, which was applied to finishing linen fabric. Dodecafluloroheptry methacrylate (G04) was used as a modified monomer, butylacrylate (BA) and methylacrylate (MMA) as soft and hard monomers.respectively, and acrylic acid as a functional monomer. Structure and properties of the products were characterised and analyzed by FTIR, TEM, PSD and CA measurements, respectively. The water and air permeability as well as the breaking force of the fabric treated were also investigated. The results showed that the fluorine-containing acrylate copolymer emulsion obtained had a core-shell structure, and the microsphere was of nanoscale size. Because of the latex film on the fabric surface, it became smooth and flat. And the increase in G04 was beneficial to the mechanical properties, waterproofness and antifouling ability of the linen fabric. When the content of G04 were increased from 0% to 20%, the water in the linen sample and hexadecane contact angles to the copolymer film increased from 113.02° to 136.08° and from 65.1° to 87.6°,respectively. Furthermore the breaking force of the linen samples was enhanced from 648 N to 721N. However, the increasing content of G04 had negative effects on the flexural rigidity as well as water and air permeability of the fabric, which were essential requirements for the fabric’s application. However, the wash resistance was excellent and the wear-resistance of the finished linen fabric was better than the unfinished linen fabric.

PL

W pracy przygotowano emulsję kopolimeru akrylanowego zawierającą fluor, którą następnie zastosowano do wykańczania tkanin lnianych. Jako modyfikowany monomer zastosowano metakrylan dodekafluoroheptan (G04), a jako miękkie i twarde monomery użyto akrylan butylu (BA) i akrylan metylu (MMA), a kwas akrylowy jako monomer funkcjonalny. Strukturę i właściwości produktów scharakteryzowano i przeanalizowano za pomocą pomiarów FTIR, TEM, PSD i CA. Przebadano również przepuszczalność wody i powietrza oraz siłę zrywania tkaniny poddanej obróbce. Wyniki wykazały, że otrzymana fluorowa emulsja kopolimeru akrylanowego miała strukturę rdzeń-otoczka, a mikrosfera miała rozmiar w nanometrach. Ze lateksowej powłoce tkanina stała się gładka i matowa. Stwierdzono, że wzrost G04 wpływa korzystnie na właściwości mechaniczne, wodoodporność i zdolność przeciwporostową tkaniny lnianej. Zwiększenie zawartości G04 spowodowało wzrost kąta zwilżania, a siła zrywania próbek zwiększyła się z 648 do 721 N. Jednak wzrastająca zawartość G04 miała negatywny wpływ na sztywność zginania, a także przepuszczalność wody i powietrza tkaniny, które były zasadniczymi cechami wymaganymi dla aplikacji tkaniny. Jednakże odporność na pranie i zużycie była lepsza w przypadku próbek powleczonych.

10

Production of Carbon Fibre Bulked Yarns by the Airflow Dispersion Method

Zhao X., Liu Y., Liu G.

Fibres & Textiles in Eastern Europe

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2017

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Vol. 25, no. 6 (126)

34--40

EN

Using carbon fibre tows as raw materials, carbon fibre bulk yarns were producedby the airflow dispersion method for the first time. The breaking strength, strength irregularity, yarn irregularity and hairiness index of the carbon fibre bulk yarn were used as evaluation indices, and preparation technology for carbon fibre bulk yarn was optimized using the orthogonal experimental method. Subsequently the disordered structure of homemade carbon fibre bulk yarn, the ability to fix the resin, and the surface contact angle were investigated. Finally infrared spectral analysis of the carbon fibre bulk yarn was carried out. Results show that the best preparation technology for carbon fibre bulk yarn is as follows: nozzle air pressure 0.45 MPa, spinning speed 150 m/min, and nozzle diameter 2.2 mm. The degree of disorder of fibres of T700 carbon fibre bulk yarn fibre is 18.70%~25.60%; as the degree of disorder of carbon fibre bulk yarn increases, the ability to fix the resin is enhanced. The process of carbon fibre tows producing bulk yarns is a physical one.

PL

W pracy wytworzono przędze puszyste z włókien węglowych metodą dyspersji przepływu powietrza, następnie zbadano ich wytrzymałość na rozerwanie, nierównomierność oraz włochatość. Przeprowadzono także spektralną analizę wiązki włókien węglowych w podczerwieni. Na podstawie otrzymanych wyników określono optymalne parametry wytwarzania przędz puszystych z włókien węglowych, tj.: ciśnienie powietrza w dyszy 0,45 MPa, prędkość wirowania 150 m/min i średnica dyszy 2,2 mm. Stopień nieuporządkowania włókien węglowych T700 wynosi 18,70 ~ 25,60%. Stwierdzono, że wraz ze wzrostem stopnia nieuporządkowania zwiększa się zdolność wiązania żywicy.

11

Preparation of Self-cleaning Polyester Fabrics by Chemical Vapor Deposition of Methyltrichlorosilane/Dimethyldichlorosilane

Zheng Z., Wang H., Zhang N., Zhao X.

Fibres & Textiles in Eastern Europe

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2017

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Vol. 25, no. 1 (121)

121--124

EN

Self-cleaning polyester fabrics were prepared by a simple gas phase deposition procedure in which a layer of polydimethylsiloxane nanofilaments was grown onto textile fibers. Superhydrophobic and self-cleaning properties, tensile breaking strength, mechanical stability and permeability of polyester fabrics were investigated. The results showed that the fabrics deposited had superhydrophobicity, and the contact angle and sliding angle of the fabric surface were 159° and 1.7°, respectively. The self-cleaning test showed that dust particles adhere to rolling water and shed from the surface of polyester fabric, leaving an extremely clean surface. In addition, the polyester fabric deposited still has excellent breaking strength and permeability. This approach is simple, inexpensive and has little effect on the mechanical properties of the fabric.

PL

Samooczyszczające tkaniny poliestrowe przygotowano metodą chemicznego osadzania z fazy gazowej, w którym warstwa nanofilamentów polidimetylosiloksanu narastała na włóknach tekstylnych powodując superhydrofobowość i nadając właściwości samoczyszczące. Po obróbce badano wytrzymałość na zerwanie, trwałość mechaniczną i przepuszczalność powietrza. Wyniki wykazały, że zmodyfikowane tkaniny miały właściwości superhydrofobowe, a kąty zwilżania i poślizgu po powierzchni tkaniny wynosiły odpowiednio 159° i 1,7°. Testy zdolności samooczyszczających wykazały, że cząsteczki pyłu przylegają do cząstek wody i wraz z nią spływają po powierzchni tkaniny poliestrowej. Zastosowana metoda jest prosta, niedroga i nie wpływa negatywnie na obrabianą tkaninę.

12

Preparation of a Cationic Environment-Friendly Fixing Agent

Liu Y., Zhao X.

Fibres & Textiles in Eastern Europe

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2017

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Vol. 25, no. 6 (126)

96--102

EN

Initially waste feather protein was used to prepare a reactive cationic crosslinking modified agent, WLS, as a starting material which was used to prepare a quaternary ammonium type cationic environment-friendly fixing agent (named WLSPR) for dyeing cotton fabric with reactive dyes after solid colour processing. In this paper, the degree of staining on white cloth from colored cloth after a soaping process was assessed (by determination of the K/S value) as well as the washing fastness etc. as the evaluation indices. The optimum synthetic conditions of fixing agent WLSPR were determined, and the structure and properties of the additives characterised. The results show that the maximum absorption wavelength of the cationic protein fixing agent WLSPR is 195nm. Synthesis of the environment-friendly fixing agent WLSPR using optimum conditions can reduce white staining during soap washing , effectively improving the cotton fabric in terms of colour fastness to washing and rubbing fastness. Based on infrared spectral characterisation, it was confirmed that the protein-based cationic auxiliary additives were synthesised.

PL

W pracy przedstawiono możliwość użycia białka z piór odpadowych do przygotowania reaktywnego kationowego środka sieciującego (WLS) będącego materiałem wyjściowym, który następnie został użyty do przygotowania czwartorzędowego amoniowego kationowego przyjaznego dla środowiska środka utrwalającego (o nazwie WLSPR) stosowanego do barwienia tkaniny bawełnianej barwnikami reaktywnymi. W artykule oceniono stopień zabrudzenia białej tkaniny barwnikami pochodzącymi z wybarwionej próbki po procesie namaczania (przez określenie wartości K/S) oraz odporność na pranie. Wyznaczono optymalne warunki stosowania środka utrwalającego WLSPR oraz scharakteryzowano strukturę i właściwości dodatków. Wyniki pokazały, że maksymalna długość fali absorpcji kationowego środka utrwalającego białko WLSPR wynosi 195 nm. Synteza przyjaznego dla środowiska środka utrwalającego WLSPR przy użyciu optymalnych warunków może zmniejszyć zabrudzenia, skutecznie poprawiając trwałość koloru tkanin bawełnianych.

13

Prediction of the Distribution of Alpine Tree Species Under Climate Change Scenarios: Larix chinensis in Taibai Mountain (China)

Zhao X., Meng H., Wang W., Yan B.

Polish Journal of Ecology

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2016

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Vol. 64, nr 2

200--212

EN

Larix chinensis, an endangered and endemic alpine tree, occurs on Mt. Taibai in the Qinling Mountains, China. The extreme sensitivity of this species to climate change makes predicting its future distribution important. Using high-resolution remote-sensing imagery, and the Maxent model, we analysed the current distribution and forecast future distribution of L. chinensis under two climate change scenarios, IPCC A2 and IPCC B2. The results showed that three dominant climatic factors influenced the geographic distribution of L. chinensis: mean annual temperature, mean temperature of the coldest quarter, and precipitation of wettest month. Currently, L. chinensis mainly concentrated at 3100 m and covers an area of 53.52 km2. The population on the southern slope covers approximately twice the area of that on the northern slope; the model simulations indicated that the area of suitable habitat would decrease continually under two climate change scenarios, A2 and B2; the decrease was more obvious in scenario A2, and the range in scenario A2 covers approximately twice the area of that in scenario B2. Under both scenarios, L. chinensis would first be extirpated at lower elevations, and the suitable habitat of this species would move to higher elevations in the Taibai Mountains.

14

Heavy Metal Contamination of Surface Water and Groundwater in and Around Gejiu Tin Mine, Southwest China

Cheng X., Qi W., Danek T., Matysek D., Huang Q., Zhao X., Zhou Z., Fang R., Zou L., Xu J.

Inżynieria Mineralna

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2016

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R. 17, nr 1

93--98

EN

Heavy metal contamination due to mining activity is a global major concern because of its potential health risks to local inhabitants. The heavy metal contamination of surface water and ground water by mining activities in Gejiu tin-polymetallic mining area, Southwest China, was studied. Surface water and ground water were sampled and analyzed using AAS for Cr6+, Cd, As, Hg, Cu, Pb, Zn, Se, Fe and Mn. Analysis of HCO3–, Cl–, SO42–, F– and NO3– in water samples was also undertaken by ion chromatography. It was shown that none of water samples exceeded the guideline of Cr6+, Se and Hg, while the contamination degree of heavy metals was Mn > Fe > Cd > Zn > Pb > As > Cu, all of which were serious contamination except mild contamination for Cu. The ground waters were polluted much worse than surface water.

PL

Zanieczyszczenie metalami ciężkimi spowodowane działalnością kopalń jest światowym problemem z powodu ryzyka utraty zdrowia przez okolicznych mieszkańców. Zbadano zanieczyszczenie wód powierzchniowych oraz wód podziemnych wywołane działalnością kopalni cyny w rejonie górniczym Gejiu, południowo-zachodnie Chiny. Pobrano próbki wody powierzchniowej oraz podziemnej i zanalizowano je ze względu na obecność Cd, As, Hg, Cu, Pb, Zn, Se, Fe oraz Mn. Analizy HCO3–, Cl–, SO42–, F– oraz NO3– w próbkach wody również zostały przeprowadzone za pomocą chromatografii jonowej. Ukazano, że żadna z badanych wód nie przekroczyła dopuszczalnych poziomów dla Cr6+, Se oraz Hg. Jednakże poziom zanieczyszczenia metali ciężkimi tj. Mn > Fe > Cd > Zn > Pb > As > Cu był wysoki, za wyjątkiem niewielkiego przekroczenia norm dla Cu. Wody podziemne były znacznie bardziej zanieczyszczone niż wody powierzchniowe.

15

Experimental Studies on the Dielectric Behaviour of Polyester Woven Fabrics

Liu Y., Zhao X.

Fibres & Textiles in Eastern Europe

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2016

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Vol. 24, no. 3 (117)

67--71

EN

In this paper, the influence of fabric structure, weft density, end spacing and yarn fineness on the dielectric constant of polyester woven fabrics was studied. The results show that at low frequencies, the dielectric constant of fabric was clearly affected by the processing parameters; when the organisation of the fabric is plain i.e. the warp density is 140/10 cm, weft density 140/10 cm and yarn linear density 32 tex, the absorbing performance of polyester woven fabrics is at its best. At higher frequencies, the effect of the varying parameters on the dielectric constant of the fabrics can be neglected. Polyester woven fabrics have better EM absorbing properties for these parameters. This study offers a new theoretical basis for the development of EM absorptive fabrics.

PL

Badano wpływ struktury tkaniny (gęstości wątku i osnowy oraz masy liniowej przędzy) na dielektryczną stałą poliestrowych tkanin. Wyniki wykazują, że przy niskich częstotliwościach stałe dielektryczne w wyraźny sposób zależą od parametrów procesu tkania. Natomiast przy wyższych częstotliwościach wpływ struktury jest znacznie mniejszy, a nawet może być pomijany. Stwierdzono, że tkaniny poliestrowe mają dobre właściwości absorpcyjne pola elektromagnetycznego. Badania stwarzają nowe podstawy teoretyczne dla opracowywania tkanin absorbujących pole elektromagnetyczne.

16

Image fusion for travel time tomography inversion

Yin X., Liu L., Zhao X., Ashraf M. A.

Polish Maritime Research

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2015

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S 1

149--156

EN

The travel time tomography technology had achieved wide application, the hinge of tomography was inversion algorithm, the ray path tracing technology had a great impact on the inversion results. In order to improve the SNR of inversion image, comprehensive utilization of inversion results with different ray tracing can be used. We presented an imaging fusion method based on improved Wilkinson iteration method. Firstly, the shortest path method and the linear travel time interpolation were used for forward calculation; then combined the improved Wilkinson iteration method with super relaxation precondition method to reduce the condition number of matrix and accelerate iterative speed, the precise integration method was used to solve the inverse matrix more precisely in tomography inversion process; finally, use wavelet transform for image fusion, obtain the final image. Therefore, the ill- conditioned linear equations were changed into iterative normal system through two times of treatment and using images with different forward algorithms for image fusion, it reduced the influence effect of measurement error on imaging. Simulation results showed that, this method can eliminate the artifacts in images effectively, it had extensive practical significance.

17

Carbon accumulation in the bulk soil and different soil fractions during the rehabilitation of desertified grassland in Horqin Sandy Land (Northern China)

Li Y., Zhao X., Wang S., Zhang F., Lian J., Huang W., Mao W.

Polish Journal of Ecology

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2015

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Vol. 63, nr 1

88--101

EN

Desertification, which affects more than two-thirds of the world’s arid and semi-arid regions, is a significant global ecological and environmental problem. There is a strong link between desertification of the drylands and emission of CO2 from soil and vegetation to the atmosphere. The Horqin Sandy Land is a severely desertified area in China’s agro-pastoral ecotone due to its fragile ecology, combined with unsustainable land management. We estimated changes of organic carbon content in the bulk soil (0–5 cm), in the light-fraction of soil organic matter (based on density fractionation), and in the various particle-size fractions in areas with mobile sand dunes after implementing grazing exclusion (12 and 27 years) and tree and shrub planting (22 and 24 years). Carbon stocks in the bulk soil and all soil density and particle-size fractions increased significantly in the exclosure and plantation plots. The average rates of carbon accumulation in the bulk soil in the exclosure and plantation plots were 16.0 and 17.8 g m-2 y-1, respectively, versus corresponding values of 2.3 and 7.1 g m-2 y-1 for the light fraction, 4.3 and 8.0 g m-2 y-1 for the coarse fraction, 5.0 and 3.4 g m-2 y-1 for the fine sand, 4.5 and 4.2 g m-2 y-1 for the very fine sand, and 1.8 and 1.8 g m-2 y-1 for the silt+clay fraction. The older the exclosure and plantation, the more carbon accumulated in the bulk soil and in each fraction. The carbon pool exceeded the level in non-desertified grasslands after 27 years of grazing exclosure and 24 years of the shrub plantation. Our results suggest that both grazing exclusion and planting trees and shrubs can restore desertified grassland, creating a high potential for sequestering soil carbon, but that the plantations appeared to accumulate soil carbon faster than the exclosures.

18

A high performance distributed sensor system with multi-intrusions simultaneous detection capability based on phase sensitive OTDR

Zhan Y., Yu Q., Wang K., Yang F., Kong Y., Zhao X.

Opto-Electronics Review

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2015

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Vol. 23, No. 3

187-194

EN

A high performance distributed sensor system with multi-intrusions simultaneous detection capability based on phase sensitive OTDR (Φ-OTDR) has been proposed and demonstrated. To improve system performance, three aspects have been investigated. Firstly, a model of one-dimensional impulse response of backscattered light and a Monte Carlo method have been used to study how the laser line width affects the system performance. Theoretical and experimental results show that the performances of the system, especially the signal-noise-ratio (SNR), decrease with the broadening of laser linewidth. Secondly, a temperature-compensated fibre Bragg grating with a 3 dB linewidth of 0.05 nm and a wavelength stability of 0.1 pm has been applied as an optical filter for effective denoising. Thirdly, a novel interrogation method for multi-intrusions simultaneous detection is proposed and applied in data denoising and processing. Consequently, benefiting from the three-in-one improvement, a high performance Φ-OTDR has been realized and four simultaneous applied intrusions have been detected and located at the same time along a 14 km sensing fibre with a spatial resolution of 6m and a high SNR of 16 dB. To the best of our knowledge, this is the most multifunctional Φ-OTDR up to now and it can be used for perimeter and/or pipeline intrusion real-time monitoring.

19

Modeling and current control strategy for a medium-voltage cascaded multilevel statcom with LCL filter

Zhao X., Shi L., Chen L., Xia Z., Bendre A. R.

Journal of Power Technologies

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2015

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Vol. 95, nr 1

1--13

EN

The Static Synchronous Compensator (STATCOM a.k.a. SVG) is widely used to regulate dynamic reactive power and to solve dynamic voltage stability problems. Modeling shows that a cascaded STATCOM, which is composed of several cascaded H-bridges, not only has strong coupling characteristics when an LCL filter is added but it is also a non-linear, multivariable system. Therefore, its practical design and application are dicult to implement. In this paper an internal decoupling control algorithm is introduced to provide independent control of the active and reactive currents. Decoupling control algorithms are proposed, and models and simulation of the decoupling are provided. We describe the setting up of a simulation and experiments with a cascaded STATCOM based on combined circuit topology with a multi-field programmable gate array (FPGA), and double-loop control algorithms with a current inner loop, and a capacitor voltage outer loop. To provide control of the current inner loop, proportional-integral (PI) and resonant controllers are used, having the control ability to cancel harmonics while compensating for the reactive power. This paper presents new current-tracing control models that compensate for the fundamental current and eliminate selective harmonics by adopting a d-q synchronous reference frame, and a discrete Fourier transform (DFT). Voltage balance is realized by introducing modulation wave distribution strategies. Furthermore, both simulation and experiments are employed to verify the feasibility and eectiveness of the control strategy.

20

Two New Decomposition Algorithms for Training Bound-Constrained Support Vector Machines

Niu L., Zhou R., Zhao X., Shi Y.

Foundations of Computing and Decision Sciences

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2015

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Vol. 40, No. 1

67--86

EN

Bound-constrained Support Vector Machine(SVM) is one of the stateof- art model for binary classification. The decomposition method is currently one of the major methods for training SVMs, especially when the nonlinear kernel is used. In this paper, we proposed two new decomposition algorithms for training bound-constrained SVMs. Projected gradient algorithm and interior point method are combined together to solve the quadratic subproblem effciently. The main difference between the two algorithms is the way of choosing working set. The first one only uses first order derivative information of the model for simplicity. The second one incorporate part of second order information into the process of working set selection, besides the gradient. Both algorithms are proved to be global convergent in theory. New algorithms is compared with the famous package BSVM. Numerical experiments on several public data sets validate the effciency of the proposed methods.