检索结果-南通市图书馆

Effects of coupling and phase imperfections in programmable photonic hexagonal waveguide meshes

在线全文

学校读者我要写书评

暂无评论

Photonics Research 2020年第2期8卷 211-218页

作者： iman ZAND WIM BOGAERTS Photonics Research Group Department of Information TechnologyGhent University-IMEC9052 GhentBelgium Center of Nano and Biophotonics Ghent University9052 GhentBelgium

We present a study of the effect of imperfections on the transmission and crosstalk in programmable photonic meshes with feedback loops consisting of tunable couplers and phase *** many elements in such a mesh can generate a multitude of parasitic paths when the couplers and phase shifters deviate even slightly from their nominal *** Monte Carlo simulations,we show that small stochastic imperfections in the phase and coupling(<1.0%)can introduce unwanted interferences and resonances and significantly deteriorate the frequency response of the *** also demonstrate that,in the presence of imperfections,the programming strategy of the unused couplers can reduce effects of such parasitics.

关键词： waveguide coupling phase

Free Vibration Analysis of Functionally Graded Plates with Multiple Circular and Non-circular Cutouts

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2012年第2期25卷 277-284页

作者： JANGHORBAN Maziar ROSTAMSOWLAT iman Department of Mechanical Engineering Shiraz BranchIslamic Azad UniversityShirazIran

Cutouts are inevitable in structures due to practical *** order to investigate the free vibration of functionally graded plates with multiple circular and non-circular cutouts,finite element method is *** volume fraction of the material constituents is assumed to follow a simple power law *** parameters considered in this paper are as follows：cutout size,cutout location,number of cutouts and different boundary *** should be mentioned that free vibration for FG plates（such as rectangular？skew？trapezoidal？circular plates） with multiple cutouts has not been studied yet and hence the results out coming from this paper may be used as bench marks for future works.

关键词： graded materials rectangular?skew?trapezoidal?circular plates multiple circular/non-circular cutouts

Active Control of A Piston-Type Absorbing Wavemaker with Fully Reflective Structure

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2020年第5期34卷 730-737页

作者： Saeed MAHJOURI Rasoul shabani Ghader REZAZADEH Peyman BADIEI Department of Mechanical Engineering Faculty of EngineeringUrmia UniversityUrmiaIran South Ural state University ChelyabinskRussian Federation cDepartment of Civil Engineering Tehran UniversityTehranIran

Multiple reflections of the waves between structure and wavemaker in hydraulic flumes could change the frequency content of the desired incident wave or result in resonance. A prominent approach to avoid multiple reflections is active control of the wavemaker. This paper proposes a simple and practical active control algorithm for piston-type wavemaker. The block diagram of the control system is presented in real time domain. It is shown that there is no need to use any transfer function or filter in the feedback and feed forward loops and the use of constant gains can yield acceptable results. In the operating frequency range(0.25-2 Hz), it is revealed that the proposed system is very effective at suppressing the excitation of resonant sloshing for regular wave. In the case of irregular waves, it is depicted that the experimental waves agree quite well with the desired wave elevation in frequency domain. In addition, comparison of the results obtained both with and without absorption discloses the good characteristics in time domain.

关键词： wave flume piston-type wavemaker active absorption mathematical modeling reflective waves

Microstructure and Corrosion Resistance of Dissimilar Weld-Joints between Duplex Stainless Steel 2205 and Austenitic Stainless Steel 316L

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2016年第3期32卷 282-290页

作者： Aboulfazl Moteshakker iman Danaee Abadan Faculty of Petroleum Engineering Petroleum University of Technology

The microstructure and corrosion resistance of dissimilar weld-joints between stainless steel SAF 2205 and stainless steel AISI 316L were investigated. Welding was accomplished by different types of welding wires AWS ER 347, AWS ER 316L and AWS ER 309L. To verify soundness of welded samples, nondestructive tests were performed. Metallographic samples were prepared from cross-section areas of weld- joints to investigate microstructure of different regions of weld-joints by optical microscopy and scanning electron microscopy. Corrosion resistance of weld-joints was evaluated in NaCI solution by potentiodynamic polarization and electrochemical impedance techniques. In the weld metal AWS ER 347, the brittle sigma phase was created, resulting in the decrease of weld-joint corrosion resistance. According to the results of metallurgical investigations and corrosion tests, welding wire AWS ER 309L was suitable for welding duplex stainless steel （SAF 2205） to austenitic stainless steel （AIS1316L） by gas tungsten arc welding （GTAW） process.

关键词： Duplex stainless steel Joint welding Microstructure Polarization Impedance

Effects of intermediate Ni layer on mechanical properties of Al–Cu layered composites fabricated through cold roll bonding

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2018年第5期25卷 573-583页

作者： Ali shabani Mohammad Reza Toroghinejad Alireza Bagheri Department of Materials Engineering Isfahan University of Technology

Layered composites have attracted considerable interest in the recent literature on metal composites. Their mechanical properties depend on the quality of the bonding provided by the intermediate layers. In this study, we analyzed the mechanical properties and bond strengths provided by the nickel layer with respect to its thickness and nature(either powder or coating). The results suggest that bond strength decreases with an increase in the content of nickel powder. At 0.3 vol% of nickel coating, we found the nature of nickel to be less efficient in terms of bond strength. A different picture arose when the content of nickel was increased and the bond strength increased in nickel coated samples. In addition, the results demonstrate that mechanical properties such as bend strength are strongly dependent on bond strength.

关键词： cold roll bonding Al/Ni/Cu composite mechanical testing metallography

Synthesis of 2,3-dihydroquinazolin-4(1H)-ones catalyzed by zirconium(Ⅳ) chloride as a mild and efficient catalyst

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2011年第10期22卷 1163-1166页

作者： Mohammad Abdollahi-Alibeik Elahe shabani Department of Chemistry Yazd UniversityYazd 89195-741Iran

2,3-Dihydroquinazolin-4（1H）-ones have been synthesized in the high to excellent yields via condensation of 2-aminobenzamide with aldehydes and ketones in the presence of catalytic amount of ZrCl_4 in EtOH at room **... 详细信息

关键词： 2 3-Dihydroquinazolin-4(1H)-one ZrCl_4 Catalysis 2-Aminobenzamide

Effect of pin penetration depth on double-sided friction stir welded joints of AA6061-T913 alloy

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2016年第3期26卷 676-683页

作者： iman HEJAZI Seyyed Ehsan MIRSALEHI Department of Mining and Metallurgical Engineering Amirkabir University of Technology (Tehran Polytechnic)424 Hafez AveP.O.Box 15875-4413TehranIran

Friction stir welding (FSW) of aluminum alloys is currently utilized in several modern industries. The joints must have sufficient elastic?plastic response and formability levels similar to that of the base metal. In this work, double-sided FSW of AA6061 sheet was compared with its conventional single-sided one. An adjustable tool with different pin lengths (50%?95% of the sheet thickness) was used to perform the double-sided welds. Macro- and micro-structures, strength, and hardness of the joints were investigated to determine the optimum pin penetration depth. The best results were obtained for a double-sided joint made by a pin length equal to 65% of the sheet thickness, which showed an increase of 41% in the ultimate tensile strength compared with the single-sided joint.

关键词： AA6061 aluminium alloy friction stir welding double-sided joint pin length mechanical properties microstructure

Thermodynamic Analysis of Liquefied Natural Gas(LNG)Production Cycle in APCI Process

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2012年第6期21卷 564-571页

作者： Shahrooz Abbasi Nezhad Bezhan shabani Majid Soleimani Department of Mechanical Engineering Langroud BranchIslamic Azad UniversityLangroudIran

The appropriate production of liquefied natural gas(LNG)with least consuming energy and maximum efficiency is quite *** this paper,LNG production cycle by means of APCI Process has been *** equilibrium equations and exergy equilibrium equations of each equipment in the APCI cycle were *** equipments are described using rigorous thermodynamics and no significant simplification is *** some operating parameters as key parameters,influences of these parameters on coefficient of performance(COP)and exergy efficiency of the cascading cycle were *** results indicate that COP and exergy efficiency will be improved with the increasing of the inlet pressure of MR(mixed refrigerant)compressors,the decreasing of the NG and MR after precooling process,outlet pressure of turbine,inlet temperature of MR compressor and NG temperature after cooling in main cryogenic heat exchanger(MCHE).The COP and exergy efficiency of the APCI cycle will be above 2% and 40%,respectively,after optimizing the key parameters.

关键词： LNG APCI process Coefficient of performance Exergy efficiency

Teflon-pad shaping process of circular metal blanks into quasi-cup specimens by theoretical and experimental methods

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2016年第1期26卷 213-227页

作者： Abbas NIKNEJAD iman KARAMI FATH Mechanical Engineering Department Yasouj University

Teflon-pad shaping process of circular metal blanks into quasi-cup specimens is investigated by theoretical and experimental methods in the quasi-static condition. In the experiments, circular metal sheets are formed into the quasi-cup samples by compressing them between a Teflon-filled die and a rigid punch with desirable shape. To investigate influences of different parameters on the forming progress, 12 rigid punches with different dimensions, two blank material types of aluminum and galvanized iron, three blank thicknesses of 0.6, 1.1 and 1.5 mm, and two Teflon-fillers of PVC and polyurethane are used in several experimental tests. In the analytical part, theoretical deformation models of metal blank and Teflon-filler are introduced and based on energy method, energy absorptions by the blank and Teflon-filler are calculated to derive a theoretical formula for predicting total required energy of the forming process. For this purpose, several energy absorption mechanisms are considered in the blank and filler. Furthermore, predictions by theoretical equation are compared with the corresponding experimental tests to study the verity of the calculated formulas. Theoretical and experimental results illustrate change trend of forming energy with respect to blank thickness. Also, the performed forming tests show that when external cone angle of rigid punch with respect to the horizontal direction increases, forming energy increases nonlinearly; and when the depth of spherical part of rigid punch increases, the probability of rupture increases. Additionally, the experiments demonstrate that there is a direct relationship between the forming energy and flow stress of the blanks. Furthermore, experimental observations illustrate that forming energy of a certain blank with PVC Teflon-filler is higher than that of a similar specimen with polyurethane Teflon-filler; but, the probability of wrinkling decreases when PVC Teflon-pad is used as the filler; and it is advantage of

关键词： Teflon-pad forming circular metal blank quasi-cup specimen PVC Teflon-filler polyurethane Teflon-filler forming energy