Wyniki wyszukiwania - BazTech

1

Modeling of acoustic field for a parametric focusing source using the spheroidal beam equation

Yu L., Li J., Shi C.

Polish Maritime Research

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2015

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S 1

43--47

EN

A theoretical model of acoustic field for a parametric focusing source on concave spherical surface is proposed. In this model, the source boundary conditions of the Spheroidal Beam Equation (SBE) for difference frequency wave excitation were studied. Propagation curves and beam patterns for difference frequency component of the acoustic field are compared with those obtained for Khokhlov-Zabolotskaya-Kuznetsov (KZK) model. The results demonstrate that the focused parametric model of SBE is good valid for a large aperture angle in the strongly focused acoustic field. It is also investigated that high directivity and good focal ability with the decreasing of downshift ratio and the increasing of half-aperture angle for the focused parametric model of SBE.

2

Construction method of the topographical features model for underwater terrain navigation

Wang L., Yu L., Zhu Y.

Polish Maritime Research

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2015

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S 1

121--125

EN

Terrain database is the reference basic for autonomous underwater vehicle (AUV) to implement underwater terrain navigation (UTN) functions, and is the important part of building topographical features model for UTN. To investigate the feasibility and correlation of a variety of terrain parameters as terrain navigation information metrics, this paper described and analyzed the underwater terrain features and topography parameters calculation method. Proposing a comprehensive evaluation method for terrain navigation information, and constructing an underwater navigation information analysis model, which is associated with topographic features. Simulation results show that the underwater terrain features, are associated with UTN information directly or indirectly, also affect the terrain matching capture probability and the positioning accuracy directly.

3

Reliability analysis of gear transmission with considering failure correlation

Zuo F.-J., Yu L., Mi J., Liu Z., Huang H.-Z.

Eksploatacja i Niezawodność

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2015

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Vol. 17, no. 4

617--623

EN

Reliability analysis is of great importance in engineering practices. However, reliability analysis of mechanical system under considering correlation for multiple failure modes is very difficult. Gear is the key component in many mechanical transmission systems and therefore its reliability analysis is very important. Based on the standards of strength calculation of gears and stressstrength interference theory as well as copula theory, the reliability of gear transmission with three failure modes, including gear bending fatigue, gear flank contact fatigue and flank adhesion, is analyzed. The correlation of the three failure modes is studied and reliability of their correlation is also evaluated based on the selected copula functions. The proposed method can be used to facilitate the design, manufacturing, and maintenance planning of gears.

PL

Analiza niezawodności ma ogromne znaczenie w praktyce inżynierskiej. Jednakże, analiza niezawodności układu mechanicznego z uwzględnieniem korelacji dla mnogich przyczyn uszkodzeń jest trudnym zadaniem. Koło zębate jest kluczowym elementem w wielu przekładniach mechanicznych i dlatego analiza jego niezawodności jest niezwykle ważna. W oparciu o normy obliczania wytrzymałości kół zębatych i teorię interferencji naprężeń i wytrzymałości, a także teorię kopuł, przeanalizowano niezawodność przekładni zębatej uwzględniając trzy przyczyny uszkodzeń: zmęczenie zginające koła zębatego, zmęczenie stykowe boku zęba i przyczepność boku. Prześledzono korelację trzech przyczyn uszkodzeń i oceniono niezawodność ich korelacji na podstawie wybranych funkcji kopuł. Proponowana metoda może być stosowana w celu ułatwienia projektowania, produkcji i planowania konserwacji przekładni.

4

Real-time mask-division technique based on DMD digital lithography

Luo N., Gao Y., Chen M., Yu L., Ye Q.

Optica Applicata

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2010

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Vol. 40, nr 1

239--248

EN

Digital lithography technique is a promising tool for the fabrication of binary optical element. In this paper, we present the mask-division technique to improve the lithography quality. A piece of high-frequency mask is divided into several pieces of low-frequency binary masks. Then they are imaged on the photoresist successively by using the DMD-based lithography system. Based on the theory of partial coherent light, the intensity distribution in image plane has been simulated. The grating masks with period of 4 žm have been fabricated by using the mask-division technique. Experimental results demonstrate the feasibility of the proposed method as an effective technique for advancing the edge sharpness.

5

The evolution of complexity in apple darwin:a common coupling point of view

Yu L.

e-Informatica Software Engineering Journal

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2010

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Vol. 4, nr 1

47--57

EN

Common coupling increases the interdependencies between software modules. It should be avoided if possible. In previous work, we presented two types of categorization of common coupling, one is for single-kernel-based software, one is for multi-kernel-based-software. In this paper, we analyze the relationships between these two types of categorization and apply them to study the evolution of the complexity of Apple Darwin. The same conclusion about Darwin's evolution is drawn based on the two types of categorization of common coupling: From version XNU-517 to version XNU-792, Darwin has restructured to reduce the number of difficulty-inducing high category (level) global variables in order to reduce the system complexity. However, due to the definition-use dependencies, the complexity of Darwin induced by global variables has increased from version XNU-517 to version XNU-792.

6

A warranty cost model with intermittent and heterogeneous usage

Hong-Zhong H., Zhi-Jie L., Yanfeng L., Yu L., Liping H.

Eksploatacja i Niezawodność

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2008

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nr 4

9-15

EN

Estimation of warranty servicing costs during the product life cycle is of great importance to the manufacturers. Earlier research has usually assumed that the product is in continuous use and the usage intensity is the same for all buyers. This paper deals with the problem of estimating the expected warranty cost for the case where the item usage is intermittent and of heterogeneous usage intensity over the product life cycle when sales occur continuously. The failure of the item is dependent on the number of times, the duration the unit has been used and the usage intensity. Also, the product sales depend on product price and design quality. We consider repairable and nonrepairable items and obtain results for the free-replacement warranty (FRW) and Pro-rata Warranty (PRW) policy. Furthermore, the models consider the infl uences of price level, investment growth and warranty execution effects for the expected warranty costs. It also incorporates the cash fl ows of warranty reserve costs at any time intervals during the product life cycle. A numerical example is given to illustrate the application of the models.

7

Chalcones from the Seeds of Psoralea corylifolia

Yu L.

Polish Journal of Chemistry

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2005

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Vol. 79 / nr 7

1173-1177

EN

Psorachalcone A, a new chalcone was isolated from the seeds of Psoralea corylifolia and assigned the structure (2E)-1-[2,4-dihydroxy-3-(2-hydroxy-3-methylbut-3- en-1-yl)phenyl]-3-(4-hydroxyphenyl)prop-2-en-1-one 1 by spectroscopic analysis including HR-ESI-MS and 2D-NMR. In addition, known chalcones corylifol B 2, isobavachalcone 3, bavachalcone 4 and bavachromene 5 were also isolated from these species.

8

Tribological behavior of cast iron and (Ca, Mg)-Sialon under lubrication

Zhang W., Liu W., Yu L., Kajdas C.

Tribologia

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2001

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nr 6

1037-1052

EN

The tribological properties of Sialon and cast iron lubricated with liquid paraffin containing different AW/EP additives and/or an alcohol were investigated with an SRV test rig. The worn surfaces of (Ca, Mg)-Sialon and cast iron were examined by means of scanning electron microscopy and X-ray photoelectron spectroscopy. As the results, slightly increased friction coefficient is recorded in sliding of Sialon against cast iron lubricated with liquid paraffin containing 2 wt.% sulfurized olefin (SO) at a relatively short test duration, while the friction coefficient decreases to some extent at an extended test duration. The other additives including zinc dialkyldithiophosphate (ZDDP), tricresyl phosphate (TCP), methanol, decanol, and their combinations have almost no effect on the friction coefficients. Those additives in liquid paraffin almost have no effect on the wear-resistance of Sialon, except that SO as additive increases the wear scar diameter of Sialon considerably and methanol increases the wear scar diameter of Sialon slightly. However, some of the additives including methanol, TCP, SO, and the combination of ZDDP with methanol increase the wear volume loss of cast iron significantly. Synergistic effect between ZDDP and methanol in reducing friction has been observed. It has also been found that the synergy is more significant for ZDDP and 1-decanol in reducing friction and wear of both Sialon and cast iron at long test duration. Moreover, Sialon shows different friction and wear behaviors in sliding against (Ca, Mg)-Sialon as compared with sliding against cast iron. In this case, the order of friction coefficient can be ranked as LP > 2% ZDDP > 2% TCP > 2% SO > 2% ZDDP+2% 1-decanol. A synergism between ZDDP and 1-decanol is also observed in this case. SO provides relatively good antiwear ability at 8ON but very weak antiwear ability at 200 N, which indicates that SO is not a good candidate as an EP additive for Sialon/cast iron and Sialon/(Ca, Mg)-Sialon systems. XPS and SEM analytical results of the worn surfaces indicate that complex tribochemical reactions are involved in Sialon/cast iron and Sialon/(Ca, Mg)-Sialon systems, which account for their different friction and wear behaviors therewith.

PL

Badano właściwości tribologiczne Sialonu i żeliwa smarowanych za pomocą ciekłej parafiny zawierającej różne dodatki AW/EP i/lub alkohol. Powierzchnie tarcia badano za pomocą skaningowej mikroskopii elektronowej i rentgenowskiej spektroskopii fotoelektronów. Stwierdzono nieznaczny wzrost współczynnika tarcia w przypadku układu sialon-żeliwo smarowanego ciekłą parafiną zawierającą 2% (m/m) siarkowanej olefiny (SO) w stosunkowo krótkim czasie trwania testu, natomiast wydłużenie czasu trwania testu powodowało spadek współczynnika tarcia. Inne dodatki, tj. dialkiloditiofosforan cynku (ZDDP), fosforan, trójkrezylu (TCP), metenol. dekanol i ich kombinacje nie wykazywały prawie żadnego wpływu na współczynnik tarcia. Niektóre dodatki, tj. metanol, TCP, SO i kompozycja ZDDP z metanolem powodowały znaczne zużycie objętościowe żeliwa. Ponadto zaobserwowano efekt synergetycznego działania pomiędzy ZDDP i metanolem w redukcji tarcia. SO wykazywał stosunkowo dobre właściwości przeciwzużyciowe przy obciążeniu 80 N, natomiast bardzo słabe przy obciążeniu 200 N. Wyniki badań XPS i SEM wskazują, iż w układach sialon-żeliwo i sialon/ (Ca, Mg) Sialon zachodzą złożone reakcje tribochemiczne.

9

Investigation of the tribological behaviors of several organic compounds as additives in rapeseed oil

Yu L., Cao Y., Xue Q.

Tribologia

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2001

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nr 5

891-904

EN

The friction-reduction, antiwear and extreme pressure properties of several hydroxy fatty acids and sulfurized fatty acids as additives in rapeseed oil were investigated with four-ball friction and wear testers. Odorless sulfurized fatty acids including sulfurized octadecenoic acid (SOA) and sulfurized docosenoic acid (SDA) were synthesized and evaluated as the additives in rapeseed oil with the same four-ball machine as well. The morphologies and elemental chemical states on the worn surfaces of the lubricated AISI52100 steel were investigated by means of X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). As the results, fatty acids as additives possess certain friction reduction and antiwear capacities but have no effect on the extreme pressure properties of the rapeseed oil. Dihydroxy fatty acids as additives in rapeseed oil show better friction- reduction and antiwear properties monohydroxy fatty acids in the same base stock. At the same time, hydroxy fatty acids with longer molecular chain length are superior to those with shorter molecular chain length in terms of friction-reduction and antiwear behaviors. XPS analysis of the worn steel surface indicates that fatty acid additives function by forming adsorption protective film. Both SOA and SDA as additives in rapeseed oil show improved extreme pressure properties and friction-reducing behavior as compared with rapeseed oil alone. They show better antiwear and extreme pressure properties than octadecenoic acid additive at relatively higher load as well. The differences in the tribological behaviors of octade cenoic acid and SOA and SDA are attributed to their different action mechanisms therein. That is, octadecenoic acid functions by forming adsorption film alone while the two sulfurized fatty acids function by forming adsorption film and tribochemical reaction film during the friction process.

PL

Za pomocą testera czterokulowego badano właściwości przeciwzużyciowe (AW) i przeciwzatarciowe (EP) wybranych hydroksykwasów tłuszczowych i siarkowanych kwasów tłuszczowych, stosowanych jako dodatki do oleju rzepakowego. Syntetyzowano bezwonne siarkowane kwasy tłuszczowe, zawierające siarkowany kwas oktadekanowy (SOA) i siarkowany kwas dokozanowy, i oceniano ich skuteczność jako dodatków do oleju rzepakowego. Stwierdzono, że polepszają one właściwości AW, natomiast nie zmieniają właściwości EP oleju rzepakowego. Dihydroksykwasy tłuszczowe redukują tarcie i wykazują właściwości przeciwzużyciowe. Im większa długość łańcucha hydroksykwasu, tym właściwości te są lepsze. Analiza XPS wykazała, że kwasy tłuszczowe, zastosowane jakod dodatki, tworzą adsorpcyjną warstwę ochronną na powierzchni stali. Zarówno SOA, jak i SDA redukują tarcie i poprawiają właściwości EP oleju rzepakowego. Wykazują lepsze właściwości AW i EP, przy stosunkowo wyższym obciążeniu. Różnice właściwości tribologicznych kwasu oktadekanowego, SOA i SDA związane są z mechanizmami ich działania. Kwas oktadekanowy podczas tarcia tworzy tylko warstwę adsorpcyjną, natomiast kwasy siarkowane - warstwę adsorpcyjną i warstwę produktów reakcji tribochemicznych.