Wyniki wyszukiwania - Biblioteka Nauki

1

A simulation model of seawater vertical temperature by using back-propagation neural network

100%

Zhao N. , Han Z.

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tom S 1

82--88

EN

This study proposed a neural-network-based model to estimate the ocean vertical water temperature from the surface temperature in the northwest Pacific Ocean. The performance of the model and the sources of errors were assessed using the Gridded Argo dataset including 576 stations with 26 vertical levels from surface (0 m)–2,000 m over the period of 2007–2009. The parameter selection, model building, stability of the neural network were also investigated. According to the results, the averaged root mean square error (RMSE) of estimated temperature was 0.7378 °C and the correlation coefficient R was 0.9967. More than 67% of the estimates from the four selected months (January, April, July and October) lay within ± 0.5 °C. When counting with errors lower than ± 1°C, the lowest percentage was 83%.

2

Optimal resource allocation for safety in distributed complex electromechanical systems

80%

Han Z. , Gao J. , Xing L. , Chen F.

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tom nr 2

4-12

EN

Existing optimal resource allocation for system safety mainly concentrates on series/parallel systems or systems that can be converted into series/parallel models. However, for some distributed complex electromechanical systems, it is very difficult or even impossible to refine them into a series/parallel model; in addition, the safety of some system units is immeasurable because of the coupling relationship complexity in the system composition structure. In this paper, a novel method based on complex networks and path set-based dynamic programming is proposed for the optimal resource allocation for maximal safety of distributed complex electromechanical systems with non-series-parallel structures. As a measurement of the system safety, safety importance is defined, which is a function of two safety feature parameters - accident loss and accident probability. A practical system is taken as an example to illustrate and verify the feasibility and applicability of the proposed method.

PL

Istniejące strategie optymalnej alokacji zasobów służące zapewnieniu bezpieczeństwa systemów skupiają się głównie na systemach szeregowo-równoległych lub na systemach, które można przekształcić w modele szeregowo-równoległe. Jednakże, w przypadku niektórych złożonych rozproszonych systemów elektromechanicznych, przetworzenie na model szeregowo-równoległy może być bardzo trudne lub wręcz niemożliwe. Dodatkowo, z powodu złożoności relacji sprzężeń w fizycznej strukturze tego rodzaju systemów, bezpieczeństwo niektórych jednostek systemowych jest niemierzalne. W niniejszym artykule przedstawiono nową metodę optymalnej alokacji zasobów gwarantującą maksymalne bezpieczeństwo złożonych rozproszonych systemów elektromechanicznych o strukturze innej niż szeregowo-równoległa. Metoda ta oparta jest na sieciach złożonych i wykorzystuje dynamiczne programowanie bazujące na zbiorach ścieżek. Jako miarę bezpieczeństwa systemu zastosowano pojęcie hierarchii bezpieczeństwa, zdefiniowane jako funkcja dwóch parametrów bezpieczeństwa: strat z tytułu awarii oraz prawdopodobieństwa awarii. Dla zilustrowania proponowanej metody i weryfikacji jej przydatności i możliwości zastosowania, przedstawiono przykład rzeczywistego systemu.

3

Research on deep joints and lode extension based on digital borehole camera technology

80%

Han Z. , Wang C. , Zhu H.

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nr Special Issue S1

EN

Structure characteristics of rock and orebody in deep borehole are obtained by borehole camera technology. By investigating on the joints and fissures in Shapinggou molybdenum mine, the dominant orientation of joint fissure in surrounding rock and orebody were statistically analyzed. Applying the theory of metallogeny and geostatistics, the relationship between joint fissure and lode’s extension direction is explored. The results indicate that joints in the orebody of ZK61borehole have only one dominant orientation SE126° <68°, however, the dominant orientations of joints in surrounding rock were SE118° <73°, SW225°<70° and SE122° <65°, NE79° <63°. Then a preliminary conclusion showed that the lode’s extension direction is specific and it is influenced by joints of surrounding rock. Results of other boreholes are generally agree well with the ZK61, suggesting the analysis reliably reflects the lode’s extension properties and the conclusion presents important references for deep ore prospecting

4

An oscillation criteria for third order neutral delay differential equations

80%

Han Z. , Li T. , Sun S. , Zhang C.

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tom Vol. 16, nr 2

295-303

EN

In this paper, we will establish some oscillation criteria for the third-order neutral delay differential equations (x(t) - a(t)x(τ (t)))''' + p(t)x(δ (t)) = 0, t ≥ t 0. To the best of our knowledge nothing is known regarding the qualitative behavior of these equations. Our results in this paper extend the results given in [Hanan, Oscillation criteria for third order differential equations, Pacific J. Math. 11 (1961) 919-944]. Some examples are considered to illustrate the main results.

5

Pre-formulation Compatibility Studies of 5-Amino-1H-tetrazole Nitrate with Several Typical Materials by Thermal and Non-thermal Techniques

80%

Guo W. , Han Z. , Lin Q. , Wang B.

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tom Vol. 15, no. 1

100--114

EN

The aim of the present study was to assess the physicochemical compatibility of a promising energetic salt, 5-amino-1H-tetrazole nitrate (5-ATN), with some typical materials. Thermal techniques (differential scanning calorimetry (DSC) and vacuum stability test (VST)) and non-thermal techniques (X-ray diffractometry (XRD) and Fourier Transform Infrared Spectroscopy (FTIR)) were applied. Five energetic materials (TNT, RDX, HMX, CL-20 and AP) and three common additives (Al, DOS and F2604-2) were tested to evaluate their compatibility with 5-ATN. Based on the DSC results, except for AP that was only partially compatible with 5-ATN, all of the selected materials exhibited good compatible with 5-ATN. The VST test further confirmed the compatibility of the 5-ATN/AP mixtures. Combined with the thermal methods, the FTIR results agreed with the DSC findings. The XRD results showed some differences.

6

Construction of time-space structure model of deep stope and stability analysis

80%

Wen Z. , Tan Y. , Han Z. , Meng F.

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2016

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tom 25

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nr 6

EN

To quantitatively characterize the evolution process of disaster-causing stress fields and to analyze the whole time domain characteristics of a stope from moving to stability, we constructed the four-dimensional time-space structure model of deep stope using PFC discrete element modeling software, and embedded transducers in the goaf area to monitor overlying strata movement characteristics. Targeting the gangue in the goaf area, the compression characteristics, energy absorption characteristics, and evolution of hulking coefficient over time during compaction are analyzed under different mining conditions. Results indicate that: 1. In the first stage of development of overlying strata, an intact time-space structure model of the stope cannot be formed. This means the stope structure has not reached final mechanical equilibrium. 2. Compression of the gangue fragments is an important mechanism of energy release of key strata as the strata are ruptured. The energy absorbed by the gangue reaches the maximum when the intact time-space structure model of the stope is formed. 3. The strength of the immediate roof is directly related to the development of the stope structure. 4. The development of the time-space structure of the stope is divided into two stages, which are marked by the time point when the advance distance is equal to the width of the working face. The above analysis can explain reasons for the delayed occurrence of dynamic disasters, laying a basis for reducing dynamic disasters.

7

Multiscale simulation of major crack/minor cracks interplay with the corrected XFEM

71%

Liu G. , Zhou D. , Bao Y. , Ma J. , Han Z.

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tom Vol. 17, no. 2

410--418

EN

The present work aims at saving computational cost of multiscale simulation on major crack/minor crack interaction problems. The multiscale extended finite element method (MsXFEM) used for the numerical simulation is developed on multiscale projection technique which enables different scale decomposition, and transition of field variables between different scales. Both macroscale and microscale problems are solved independently and alternatively, in the framework of XFEM. The improvement made in this paper is to employ corrected XFEM on the macroscale level, so that a more accurate boundary condition can be obtained for the microscale problem. The modification leads to a reduced necessary microscale domain size, meanwhile a solution of higher accuracy and enhanced convergence rate can be achieved. The numerical examples of minor cracks near a major one are studied, which show that the effect of minor cracks on major crack can be efficiently captured.

8

Application of ionic liquid-based ultrasonic-assisted extraction followed by rapid resolution LC-ESI/MS to chromone analysis from radix saposhnikoviae

71%

Han Z. , Xu M. , Wang Y. , Yang L. , Han M.

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tom Vol. 29, no. 3

359--374

EN

Ionic liquid-based ultrasonic-assisted extraction (ILUAE) was successfully applied to the extraction of the four chromones (prim-O-glucosylcimifugin, cimifugin, 5-O-methylvisammioside, and sec-O-glucosylhamaudol) from Saposhnikovia divaricata (Radix Saposhnikoviae) for the first time. A series of l-alkyl-3-methylimidazolium ILs differing in anion and cation compositions was evaluated for extraction efficiency, and [C3MIM]Br was selected as the optimal solvent. In addition, ultrasound extraction parameters were optimized, and the chromones were directly quantified and analyzed by rapid resolution liquid chromatography-electrospray ionization/mass spectrometry (RRLC-ESI/MS). The optimal conditions were as follows: 0.4 M concentration of [C3MIM]Br, 20:1 solvent to solid ratio, and ultrasonic time, temperature, and frequency of 5 min, 40 °C, and 50 kHz, respectively. This approach obtained the highest extraction yield of 10.188 ± 0.473 mg g−1 for total chromones. Compared with regular UAE, the proposed approach exhibited a higher efficiency (61.56% increase) and shorter extraction time (nine times shorter). Also, ILUAE was an efficient, rapid, and simple sample preparation technique for extraction of chromones, and the established RRLC-DAD method could serve as a rapid and effective technique for extracting chromones from Radix Saposhnikoviae.

9

Cloning and characterization of MxHA7, a plasma membrane H+ - ATPase gene related to high tolerance of Malus xiaojinensis to iron deficiency

71%

Zha Q. , Zhang Q. , Zhang X. , Han Z. , Wang Y.

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nr 04

EN

Malus xiaojinensis, an iron-efficient apple rootstock, was used to study the molecular mechanisms of iron uptake. Increased H⁺ extrusion under iron-deficient conditions has been related with H⁺-ATPases. Thus, a 2,901-bp plasma membrane H⁺-ATPase gene, MxHA7, encoding 966 amino acids was isolated. Quantitative realtime PCR showed that MxHA7 was specifically induced in the roots of M. xiaojinensis during iron-deficient conditions, not in M. baccata. A functional complementation assay indicated that the high tolerance of MxHA7-transgenic aha7 Arabidopsis thaliana (HA7) plants to iron deficiency was significantly enhanced. Under iron-deficient conditions, Fe²⁺ contents in the roots and chlorophyll concentrations in the leaves of HA7 plants were increased up to about 2 to 3 times compared to Col-0, aha7 and empty vector (EV) (aha7 transformed with an empty vector) plants. The zinc and manganese contents in the roots of HA7 plants were also higher significantly than in aha7 and EV plants under iron-deficient conditions. Meantime, the HA7 plants have less increasing for iron uptake-related genes than those Col-0, aha7 and EV other plants after iron deficiency, which means MxHA7 gene apparently contributed to help Arabidopsis tolerance to iron deficiency.

10

Anchoring principles of a new energy-absorbing expandable rock bolt

71%

Wen Z. , Jiang Y. , Han Z. , Yang S. , Wang X.

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2016

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tom Vol. 64, iss. 1

89--103

EN

The greater the mine, the harder stability control will be. And the conventional rock bolts do not adapt well to the severe rock stress conditions. An ideal bolt having a high resistance and large deformation should be developed. Based on the test results and theoretical study, this paper proposes an energy-absorbing expandable rock bolt, which consists of the bar, sleeve, bolt plate, nut, and bolt end. The anchoring mechanism and its efficiency were systematically analysed in the laboratory and in practice: the anchoring mechanism and supporting density, especially the quantitative relationship, were deduced under the Energy Balance Theory, that is, EB = 1 2 · n · F0 (u0 + 2∆u). As Compared with the conventional bolt and large deformation bolts, the new type of bolt could provide a larger constant resistance, even in the soft rock roadway with large squeezing deformation, the pulling force can be achieved by F = A · σ · f2, it mainly being generated by a normal stress acting on the pore surface. These characteristics are helpful in making the supported roadway safe. The amount of released energy during the large deforming process of the surrounding rock is expressed through conservation of energy, which can provide reference to the quantitative calculation of the bolt supporting system.

11

Shear properties of a honeycomb structure with zero Poisson’s ratio

61%

Song L. , Sun Y. , Han Z. , Wang T. , Wang H. , Yin C. , Shen X.

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2023

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tom Vol. 75, nr 5

521--541

EN

Honeycomb structures with zero Poisson’s ratio show promising potential for application in variable-sweep wing aircraft. The shear properties of these honeycomb structures serve as a crucial indicator of their morphing capacity. This paper derives the linear and non-linear shear properties of a honeycomb structure with zero Poisson’s ratio. A modified factor is introduced to establish a relationship between the linear and non-linear shear modulus of the honeycomb structure, simplifying the calculation method of the non-linear shear modulus. The validity of theoretical predictions is then confirmed using the finite element method Furthermore, the influences of the geometric parameters on the shear properties of the honeycomb structure with zero Poisson’s ratio are investigated, highlighting the varying contributions of these cell geometric parameters to the shear properties.