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1

Kinetic research of quinoline, pyridine and phenol adsorption on modified coking coal

Sun X., Xu H., Wang J., Ning K., Huang G., Yu Y., Ma L.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 3

965--974

EN

Adsorption is widely used in wastewater treatment. In this work, the removal of quinoline, pyridine and phenol from coking wastewater by using modified coking coal, which was treated by four different modification methods i.e. acidification sodium hydroxide (5 mol/dm3), hydrochloric acid (5 mol/dm3) and acetic acid (5 mol/dm3) and low-temperature (105 oC) oxidation, was investigated. The modified coal was characterized by the surface area analysis, SEM, total acidity and basicity and FT-IR. The results showed that the surface area from high to low follows the order: modification with acetic acid, modification with hydrochloric acid, raw coal, modification with sodium hydroxide and modification with low-temperature. Experimental data were fitted to pseudo-first-order, pseudo-second-order and intra-particle diffusion. The adsorption of all followed pseudo-second-order kinetics. The result showed that the removal efficiency of coal modified by hydrochloric acid and acetic acid are higher than raw coal, while modified by sodium hydroxide and low-temperature are lower than raw coal., The coal modified by hydroxide acid had the best adsorption capacity.

2

A Color Image Watermarking Approach Based on Synchronization Correction

Wang X., Xu H., Zhang S., Liang L., Niu P., Yang H.

Fundamenta Informaticae

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2018

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Vol. 158, nr 4

385--407

EN

Digital watermarking has been proposed as an effective technology of copyright protection and content authentication, yet up to now, research on the robust watermarking against geometric attacks is still a challenging task. This paper presents a novel robust watermarking algorithm in nonsubsampled shearlet transform (NSST) domain using quaternion polar harmonic transform (PHT) and least squares support vector regression (LS-SVR), which is a recently developed geometric correction algorithm for digital color image. The major innovative works of the proposed approach lie in that (1) the NSST is applied to embed the watermark, which can provide the image function with nearly optimal approximation and employ fully the properties of human visual system (HVS), (2) the robust 2D transform, namely quaternion PHT is introduced to represent the characteristics of color image, and (3) the novel synchronous correction method is proposed using the excellent LS-SVR and quaternion PHTs, which can accurately estimate the geometric distortions parameters. In our experiments, we applied the proposed method to the standard color image test dataset, and the experimental results demonstrate that the proposed algorithm is not only invisible, but also robustness against common signal processing operations and geometric attacks.

3

Effect of gas holdup on the efficiency of cyclonic-static microbubble flotation column for oily wastewater treatment

Ning K., Huang G., Xu H., Wu L., Li X., Wang Y.

Environment Protection Engineering

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2018

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Vol. 44, nr 2

5--17

EN

A cyclonic-static microbubble flotation column of a novel construction was used in oil-water separation fields and has high efficiency for oil-water separation. The gas holdup is a key parameter for the evaluation of the performance of a flotation column. The gas holdup, closely related to the bubble size, bubble velocity and superficial gas velocity, is one of the most important parameters characterizing the hydrodynamics of a bubble column. The effect of gas holdup in a cyclonic-static microbubble flotation column was investigated. In addition, several operating parameters such as the circulating pressure, superficial gas velocity, and frother consumption were also investigated. The gas holdup was positively correlated to the superficial gas velocity. The gas holdup of clean water and oil wastewater increased along with the increase of the frother consumption. The separation mechanism of cyclonic-static microbubble flotation column was analyzed.

4

Climatic Response of Tracheid Features of Picea meyeri Along Altitude Gradient of Luyashan Mountains of North China

Wang M., Jiang Y., Zhang W., Dong M., Kang M., Xu H.

Polish Journal of Ecology

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2017

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Vol. 65, nr 4

345--358

EN

Changing localized environmental conditions along altitude gradients could modify the responses of tree xylem structures to climate variations. To explore how trees adapt to local environment and respond to climate variants, we analysed the variation of Picea meyeri xylem tracheid features and the relationships with climate variables along an altitude gradient (1970, 2240, 2490 and 2650 m above sea level) of the Luyashan Mountains in the North China. The results mainly indicated the following: (1) tracheid number and diameter of P. meyeri showed significant differences among the four sites along the altitude gradient; (2) trees at site 2 (2240 m) and site 3 (2490 m) are similar in age, but the xylem tracheid number and diameter of these trees were significantly different, which may indicate different functional adaptation; (3) the relationships between xylem features' residual chronologies and the monthly climate data were inconsistent along altitude gradients, which indicated that the limiting factor of P. meyeri growth along the altitude gradients, shifted from drought stress at lower altitudes to low-temperature stress at higher altitudes.

5

Energy feature of a multi-flow column flotation process

Cheng G., Yu Y., Ma L., Xia W., Xu H.

Physicochemical Problems of Mineral Processing

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2017

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Vol. 53, iss. 2

1266--1284

EN

A cyclonic-static micro-bubble flotation column (FCSMC) has been widely used in mineral separation. FCSMC includes countercurrent, cyclone and jet flow mineralization zones in a single column. In this study, the energy feature of the three different zones was compared. The turbulent flow was evaluated in terms of the turbulent kinetic energy (k) and the turbulent dissipation rate (ε). An appropriate computing model was determined by comparing the flow field value measured by PIV with the results of the Fluent numerical simulation. Jet flow separation exhibited the maximum k and ε values among the three columns, whereas counter-current separation displayed the minimum values. The high circulating volumetric flowrate means great energy input and turbulent intensity. The higher turbulent dissipation rate, the smaller the bubble is. The better performance of the FCSMC was mainly attributed to the multiple mineralization steps. The floatability of mineral particles gradually decreases with an increase in flotation time, the mineralization energy gradually increased to overcome the decrease in mineral floatability. By contrast, the countercurrent was beneficial for recovering the coarse particles, and the jet flow was beneficial for recovering the fine particles.

6

A study of bubble-particle interactions in a column flotation process

Cheng G., Shi C., Yan X., Zhang Z., Xu H., Lu Y.

Physicochemical Problems of Mineral Processing

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2017

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Vol. 53, iss. 1

17--33

EN

Bubble-particle interactions play an important role in flotation. This study examines the behaviour of bubble clusters in a turbulent flotation cell. Particularly, the bubble-particle interaction characteristics in flotation are investigated. The bubble size in a flotation column was measured using an Olympus i-SPEED 3 high-speed camera. Relationships between the circulating volume, bubble size and bubble terminal velocity were discussed. Probabilities of collision, attachment, detachment and acquisition between bubbles and particles in different circulating volumes were calculated based on the flotation kinetic theory. Using the extended Derjaguin–Landau–Verwey–Overbeek (EDLVO) theory, the relationship between the potential energy and distance in bubble-particle interaction was analysed. The results demonstrated that as the circulating volume increased, the bubble size and velocity decreased. When the circulating volume increased from 0.253 to 0.495 m3/h, the bubble diameter decreased from 511 to 462 μm, and the corresponding bubble velocity decreased from 43.1 to 37.5 mm/s. When the circulating volume remained constant as the particle size increased, probabilities of collision, attachment, detachment and acquisition increased. When the particle size remained constant as the circulating volume increased, these probabilities also increased. At a constant circulating volume as the particle size increased, the absolute value of the total potential energy between the particle and bubble increased. When the distance between the bubble and particle was 30 nm, the energy barrier appeared.

7

Evaluation of the effect of variable compression ratios performance on opposed piston 2-stroke engine

Alqahtani A., Wyszynski M. L., Mazuro P., Xu H.

Combustion Engines

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2017

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R. 56, nr 4

97--106

EN

Numerous skills involving the introduction of (OP) opposed piston engine have been developed in the recent past. Indeed, novel techniques can help to improve the performance of the engine. The aim of this paper is to model and simulate a simple single-cylinder two-stroke opposed-piston engine and minimise fuel consumption and heat loss, using the software programme AVL BOOST™. AVL BOOST is an engine modelling software, which analyses the performance of a modelled single cylinder two-stroke opposed-piston engine by changing desired parameters. In order to meet this aim, experimental results from a unique engine are used to make a comparison with the results obtained from AVL BOOST model. Six combinations of compression ratios (12, 13.5, 15, 16.5, 18 and 19.5) are analysed in this study with the engine speed running at 420 rpm and 1500 rpm. In addition to the compression ratios, the effect of stroke-to-bore (S/B) ratios on OP2S performance is investigated. Various values of S/B ratios, whilst maintaining a constant swept volume, port geometry and combustion timing, and their effect on fuel consumption and heat loss are analysed in this study. A comparison between the two engine speeds with increasing combinations of compression ratios, and the S/B ratios revealed minimal differences in peak pressure, peak temperature, IMEP, ISFC, indicated efficiency and total heat loss. Detailed analyses of these parameters are highlighted in discrete sections of this paper.

8

On the structure of a class of distributions obeying the principle of a single big jump

Xu H., Scheutzow M., Wang Y., Cui Z.

Probability and Mathematical Statistics

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2016

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Vol. 36, Fasc. 1

121--135

EN

In this paper, we present several heavy-tailed distributions belonging to the new class J of distributions obeying the principle of a single big jump introduced by Beck et al. (2015). We describe the structure of this class from different angles. First, we show that heavy-tailed distributions in the class J are automatically strongly heavy-tailed and thus have tails which are not too irregular. Second, we show that such distributions are not necessarily weakly tail equivalent to a subexponential distribution. We also show that the class of heavy-tailed distributions in J which are neither long-tailed nor dominatedly-varying-tailed is not only non-empty but even quite rich in the sense that it has a non-empty intersection with several other well-established classes. In addition, the integrated tail distribution of some particular of these distributions shows that the Pakes-Veraverbeke-Embrechts theorem for the class J does not hold trivially.

9

Assessing the Suitability of Habitat for Wintering Siberian Cranes (Leucogeranus leucogeranus) at Different Water Levels in Poyang Lake Area, China

Chen B., Cui P., Xu H., Lu X., Lei J., Wu Y., Shao M., Ding H., Wu J., Cao M., Liu G.

Polish Journal of Ecology

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2016

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Vol. 64, nr 1

84--97

EN

Poyang lake area (1000–3246 km2) is the most important wintering ground for the globally critically endangered Siberian crane (Leucogeranus leucogeranus). More than 98% of the Siberian crane population overwinters in Poyang lake area. Remote-sensing and the spatial analysis tools of geographic information system (GIS) technology were used to assess the suitability of the habitat for wintering Siberian cranes in Poyang lake area at different water levels. The results demonstrated that as the water level increased within the range of 7.93–12.16 m, the area of unsuitable habitat increased gradually, but the areas of good, fair and poor habitat decreased. When the water level reached 12.16 m, good habitat for Siberian cranes covered an area of only 3005 ha, which is only 0.93% of the area of the total lake area. When human disturbance factors including vehicles, fishing and construction activities were added to the analysis of the current distribution of Siberian crane habitat, the results again indicated that the area of good habitat decreased with an increase in water level within the range of 7.93–12.16 m. Additionally, the areas of good habitat occurred primarily in the region of two national nature reserves, which are the Poyang Lake National Nature Reserve and the Nanjishan National Nature Reserve. Our study provides important data and an important theoretical basis for water level management and nature reserve construction in Poyang lake area.

10

Removal of quinoline from aqueous solutions by lignite, coking coal and anthracite. Adsorption isotherms and thermodynamics

Xu H., Huagn G., Li X., Gao L., Wang Y.

Physicochemical Problems of Mineral Processing

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2016

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Vol. 52, iss. 1

214--227

EN

Based on the concept of circular economy, a novel method of industrial organic wastewater treatment by using adsorption on coal is introduced. Coal is used to adsorb organic pollutants from coking wastewaters. After adsorption, the coal would be used for its original purpose, its value is not reduced and the pollutant is thus recycled. Through systemic circulation of coking wastewater zero emissions can be achieved. Lignite, coking coal and anthracite were used as adsorbents in batch experiments. The quinoline removal efficiency of coal adsorption was investigated. The coking coal and anthracite exhibited properties well-suited for adsorption onto both adsorbents. The experimental data were fitted to Langmuir and Freundlich isotherms as well as Temkin, Redlich–Peterson (R-P) and Dubinin-Radushkevich (D-R) models. Both Freundlich Isotherm and D-R model provided reasonable models of the adsorption process. The thermodynamic parameters of quinoline adsorption on coking coal were calculated. The thermodynamic parameters indicated that the adsorption process is exothermic and is a physical adsorption. The △S° value indicated that the adsorption entropy decreased because the adsorbate molecule was under restrictions after it adsorption on the coal surface. The coal adsorption method for removing refractory organic pollutants is a great hope for achieving zero emission waste water for a coking plant.

11

Removal of quinoline from aqueous solutions by lignite, coking coal and anthracite. Adsorption kinetics

Xu H., Wang Y., Huagn G., Fan G., Gao L., Li X.

Physicochemical Problems of Mineral Processing

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2016

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Vol. 52, iss. 1

397--408

EN

Basing on the concept of circular economy, a novel method of industrial organic wastewater treatment by using adsorption on coal is introduced. Coal is used to adsorb organic pollutants from coking wastewaters. After adsorption, the coal would be used in its original purpose, as its value was not reduced and the pollutant was reused. Through the systemic circulation of coking wastewater zero emissions can be achieved. Lignite, coking coal and anthracite were used as adsorbents in batch experiments. The quinoline removal efficiency of coal adsorption was investigated. Both the coking coal and anthracite exhibited properties well-suited for quinoline adsorption removal. The experimental data were fitted to the pseudo-first- order and pseudo-second-order kinetic equations as well as intraparticle diffusion and Bangham models. An attempt was made to find the rate-limiting step involved in the adsorption processes. Both boundary-layer diffusion and intraparticle diffusion are likely involved in the rate-limiting mechanisms. Effect of pH on coal adsorptions by coking coal was investigated. The process of quinoline adsorption on coal was researched. The coal adsorption method for removing refractory organic pollutants is a great hope for achieving wastewater zero emission for coking plants.

12

Pretreatment of coking wastewater by an adsorption process using fine coking coal

Gao L., Li S., Wang Y., Gui X., Xu H.

Physicochemical Problems of Mineral Processing

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2016

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Vol. 52, iss. 1

422--436

EN

A new technique for pretreatment of coking wastewater is introduced based on the concept of circular economy. Coal is fed into a coking system after adsorption. This study validates the feasibility of using coking coal to adsorb organic pollutants in coking wastewater. The sorption kinetics and equilibrium sorption isotherms of coking coal for removal of chemical oxygen demand (COD) and phenol from coking wastewater was also discussed in this paper. Gas chromatograph/mass spectroscopy (GC/MS) was used to detect changes in the quality of coking wastewater. The results showed that when coking coal dosage was 120 g/dm3, 65% of COD and 34% of phenol in waste water can be removed after 40 min of agitation. The surface functional groups of coking coal before and after adsorption were observed with a Fourier transform infrared spectrometer. The kinetics of COD and phenol adsorption from coking wastewater by coking coal fitted the pseudo second-order model. The adsorption process of coking coal can be classified into two categories, namely, rapid and slow. The Freundlich isotherm provided a better fit with all adsorption isotherms than the Langmuir isotherm. Coking coal could be a suitable low-cost adsorbent for recalcitrant organic pollutants.

13

Adsorption mechanism of sodium oleate on titanium dioxide coated sensor surface using quartz crystal microbalance with dissipation

Fan G., Liu J., Cao Y., Feng L., Xu H.

Physicochemical Problems of Mineral Processing

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2016

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Vol. 52, iss. 2

597--608

EN

Quartz Crystal Microbalance with Dissipation (QCM-D) was firstly applied to investigate the adsorption mechanism of sodium oleate on TiO2 coated sensor surface. The effects of pH value, sodium oleate concentration, and temperature on TiO2 coated sensor surface were evaluated systematically using the QCM-D technique. Zeta potential, surface tension, adsorption isotherms, and adsorption thermodynamics were employed to characterize the adsorption process. The results showed the advantages of QCM-D on the investigation of the adsorption process. Additionally, the electrostatic equilibrium adsorption data was well matched to the Langmuir isotherm. Based on the thermodynamic analysis, adsorption was a spontaneous and endothermic physisorption process.

14

Stability control of propeller Autonomous Underwater Vehicle based on combined sections method

Qi D., Feng J., Liu A., Hu J., Xu H., Li Y., Ashraf M. A.

Polish Maritime Research

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2015

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S 1

157--162

EN

Learning from the motion principle of quadrotor, a symmetric propeller AUV, which has small size and low velocity is designed. Compared with the AUV equipped with rudders, it has better maneuverability and manipulation at low velocity. According to the Newton-Euler method, the 6 DOF kinematic model and dynamic model of the propeller AUV are established. A stability controller that consists of 3 different PID controllers is designed. It makes the depth and attitude angle as trigger conditions, and the relevant controller is chosen in different moving process. The simulation experiments simulate ideal motion state and disturbed motion state, and experiments results show that the stability controller based on combined sections method can make the best of mature technology of PID, and meet the control requirements in different stages. It has a higher respond speed and accuracy, improving the stability of the propeller AUV under the disturbance of complex ocean currents.

15

Two-phase synthesis of olive-like NiS particles and chain-like Bi2S3 nanowires

Yuan Y., Xu H., Meng X., Han Q.

Materials Science Poland

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2015

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Vol. 33, No. 1

1--5

EN

Highly dispersed olive-like NiS particles were synthesized in a liquid-liquid biphasic system at room temperature, where nickel xanthate in organic solvents (toluene and benzene) and sodium sulfide in water solution were used as nickel and sulfide sources, respectively. NiS particles were formed at the stabilized phase interface. The structures, chemical composition and optical characteristics of the products were investigated by transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and ultraviolet-visible spectroscopy. The organic solvents obviously influenced the morphology of the NiS particles. The olive-like NiS with smooth surface and sharp ends was obtained at benzene/water interface, while spindle-like NiS particles with rough surface and circle ends were formed when using toluene as a solvent. Analogously, chainlike Bi2S3 nanowires were produced at chloroform/water interface. The effect of the experiment parameters including reaction time, solvent and concentration of reactants on the size and morphology of the products was discussed in detail and a possible formation mechanism was suggested.

16

The potential effects of climate change on suitable habitat for the Sichuan Hill Partridge (Arborophila rufipectus, Boulton) based on the maximum entropy modeling

Lei J., Xu H., Cui P., Guang Q., Ding H.

Polish Journal of Ecology

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2014

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Vol. 62, nr 4

771--787

EN

Climate change is considered one of the greatest threats to biodiversity in future decades. Learning about the habitat preferences and geographical distributions of endangered species is critical for conservation management and planning in the context of climate change. This study investigated the effects of climate change on suitable habitat for Arborophila rufipectus Boulton, an endangered species that is endemic to southwest China. We used the known presence records for this species and a series of environmental variable layers to develop a predictive distribution model using maximum entropy modelling; this model was then used to assess the effects of future climate change on suitable habitat for this species. Our study indicated that climate change might have significant effects on suitable habitat for this species. By 2050, under a no-dispersal hypothesis, more than four-fifths of the habitat currently assessed as suitable would be lost, and the mean latitude of suitable habitat would shift northward by more than 100 kilometres. Based on this model, climate change would also aggravate habitat fragmentation. Under a full-dispersal hypothesis, all four climate trajectories developed by the Canadian Centre for Climate Modelling and Analysis (Ccma) and the Commonwealth Scientific and Industrial Research Organization (CSIRO) present similar trends: the area of suitable habitat is predicted to increase substantially, and habitat fragmentation would be mitigated under the two climate trajectories developed by the Goddard Institute for Space Studies (GISS). Finally, we offer some practical proposals for the future conservation of this endangered species.

17

Experimental study on blending diesel fuel with dimethyl carbonate with aid of ultrasonic emulsification process

Wang Z., Wyszynski M. L., Xu H.

Archivum Combustionis

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2014

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Vol. 34 nr 1

35—48

EN

Blending dimethyl carbonate (DMC, oxygenated fuel additive) with ultra low sulphur diesel fuel can lower soot emissions but the blend has poor stability and short shelflife. To address this problem, ultrasonic emulsification method was employed to improve the process. Multiple tests determined by orthogonal array approach were carried out to investigate impact of several factors (temperature, emulsifier content and processing duration) on blend stability. After blends were processed, their viscosities were measured and stabilities were quantified using the measurement of light absorbance (Abs) with an UV-visible spectrophotometer. The results suggested that this processing method can greatly enhance blend stability and slightly lower viscosity. The percentage of emulsifier was the most important factor, followed by temperature, while processing duration was the least deciding one. The optimised processing condition was obtained when ultrasonic exposure duration was 10 minutes, and temperature was 20°C with a gasoline content of 4% used as emulsifier.

18

Stumpage Forestry Data Mining based on 3D Laser Point Cloud

Yun T., Xu H., Gao M., Tang C.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 1b

155--158

EN

Terrestrial laser scanner (TLS) was used to obtain stumpage point cloud data. Firstly, we used the ball neighbourhood combining with a uniform grid method to represent the spatial topology construction of the point cloud, thereby reduced the amount of calculation. Secondly, we used Hough transform to calculate timber volume and abandoned branches and leaves interference according to different depth circular centers continuity. Thirdly through calculating the point cloud features, such as normal vector, curvature, bending, etc, then automatically located the secondary branches position; Finally, comparing with the really measurement trees parameters; the effectiveness of our proposed method is proved.

PL

W artykule przedstawiono wyniki prac dotyczących wykorzystania laserowego skanera przestrzeni (ang. Terrestrial Laser Scanner – TLS) do uzyskania danych dotyczących ilości drewna na danym terenie, w celu ustalenia opłaty wycinkowej. W tworzeniu struktury przestrzennej chmury danych, wykorzystano metodę siatki jednolitej w połączeniu z kulistą formą otoczenia, co dało ograniczenie liczby obliczeń. W drugim etapie zastosowano transformację Hougha, do obliczenia ilości drewna, wolnych gałęzi i zakłóceń wywołanych liśćmi, a na koniec wyznaczono parametry chmury danych, jak wektor normalny, krzywizna, zagięcia itp. Porównanie z danymi rzeczywistymi potwierdza skuteczność metody.

19

Optimization of Neural Network Model Design: An Electoral Cooperative Particle Swarm Optimization Approach

Li D., Xu H.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 1b

165--167

EN

This paper proposes an electoral cooperative particle swarm optimization approach to optimize the model of neural network from both structure and linked weights. Different with other related research work, a new encoding method is adopted to divide the neural network into several modules, each of them corresponding to a sub-swarm. Based on the experiments on typical problems and classic dataset, the results show that the proposed algorithm outperforms all the compared ones in perspective of test error, correctness, connection number, and the CPU time of the training phase.

PL

W przedstawionym artykule opisano zastosowanie metod optymalizacji roju cząstek do optymalizacji struktury i współczynników wagowych sieci neuronowej. Zaimplementowano nową metodę analizy, do dzielenia podzielenia sieci na moduły, reprezentujące mniejsze roje. Weryfikacja eksperymentalna i porównanie z metodami klasycznymi wykazały wysoką sprawność i skuteczność analizy.

20

Fixed final time optimal adaptive control of linear discrete-time systems in input-output form

Zhao Q., Xu H., Jagannathan S.

Journal of Artificial Intelligence and Soft Computing Research

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2013

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Vol. 3, No. 3

175--187

EN

In this paper, the fixed final time adaptive optimal regulation of discrete-time linear systems with unknown system dynamics is addressed. First, by transforming the linear systems into the input/output form, the adaptive optimal control design depends only on the measured outputs and past inputs instead of state measurements. Next, due to the time-varying nature of finite-horizon, a novel online adaptive estimator is proposed by utilizing an online approximator to relax the requirement on the system dynamics. An additional error term corresponding to the terminal constraint is defined and minimized overtime. No policy/value iteration is performed by the novel parameter update law which is updated once a sampling interval. The proposed control design yields an online and forward-in-time solution which enjoys great practical advantages. Stability of the system is demonstrated by Lyapunov analysis while simulation results verify the effectiveness of the propose approach.