Investigation of Formation Process of the Chrome-free Passivation Film of Electrodeposited Zinc

The feasibility was investigated to substitute chrome-free passivation treatment of electrodeposited zinc in a titanium bath for chromate passivation treatment. The formation mechanism of the chrome-free passivation film was further analyzed. The surface mor- phologies and the elemental compositions of the treated samples with varied immersion times were observed by scanning electron mi- croscopy (SEM) and determined by energy dispersion spectrometry (EDS), respectively. The electrode potential of the sample surface was recorded in the film formation process. The changes of the electrode potential are in accordance with that of SEM and EDS of the sample surface. The results of X-ray photoelectron spectroscopy (XPS) show the chrome-free passivation film composed of ZnO, SiO2, TiO2, Zn4Si2O7(OH)2, and SrF2. The anode zinc dissolution and the local pH value increase due to the cathode hydrogen ion reduction process result in the formation of the chrome-free passivation film. The macro-images of the chrome-free passivation films formed on electrodeposited zinc show that the color of the film changes from blue to iridescence with the increase of the immersion times.     

Combination of classifiers with incomplete frames of discernment

The methods for combining multiple classifiers based on belief functions require to work with a common and complete(closed) Frame of Discernment(Fo D) on which the belief functions are defined before making their combination. This theoretical requirement is however difficult to satisfy in practice because some abnormal(or unknown) objects that do not belong to any predefined class of the Fo D can appear in real classification applications. The classifiers learnt using different attributes inform...     

Research on Feature Extraction of Remnant Particles of Aerospace Relays

The existence of remnant particles, which significantly reduce the reliability of relays, is a serious problem for aerospace relays. The traditional method for detecting remnant particles—particle impact noise detection (PIND)—can be used merely to detect the existence of the particle; it is not able to provide any information about the particles’ material. However, information on the material of the particles is very helpful for analyzing the causes of remnants. By analyzing the output acoustic signals from a PIND tester, this paper proposes three feature extraction methods: unit energy average pulse durative time, shape parameter of signal power spectral density (PSD), and pulse linear predictive coding coefficient sequence. These methods allow identified remnants to be classified into four categories based on their material. Furthermore, we prove the validity of this new method by processing PIND signals from actual tests.     

Numerical Modeling of the Compression Process of Elastic Open-cell Foams

The random models of open-cell foams that can reflect the actual cell geometrical properties are constructed with the Voronoi technique. The compression process of elastic open-cell foams is simulated with the nonlinear calculation module of finite element analysis program. In order to get the general results applicable to this kind of materials, the dimensionless compressive stress is used and the stress-strain curves of foam models with different geometrical properties are obtained. Then, the influences of open-cell geometrical properties, including the shape of strut cross section, relative density and cell shape irregularity, on the compressive nonlinear mechani- cal performance are analyzed. In addition, the numerical results are compared with the predicted results of cubic staggering model. Numerical results indicate that the simulated results reflect the compressive process of foams quite well and the geometrical properties of cell have significant influences on the nonlinear mechanical behavior of foams.     

Improvement of Aircraft Rolling Power by Use of Piezoelectric Actuators

利用分布粘贴在矩形机翼上下两面的压电驱动器，验证了使用该类结构提高飞行器横滚能力的可能性。针对常规的副翼操纵面与虚拟操纵面(Fictitious Control Surface)两种方案，比较了在不同速压或不同刚度下两类方案的表现。分析结果表明二者有本质的差别：对于常规的副翼操纵方案，气动弹性效应是不利的，必须保证机翼具有足够的结构刚度以防止副翼反效问题；但对于虚拟操纵面方案，气动弹性效应是有利的，可以使用较小的能量控制较为柔软的机翼达到要求的横滚性能。计算结果显示，利用压电驱动器的方案可以大大减少结构重量。     

Simulation and Analysis of Crashworthiness of Fuel Tank for Helicopters

Crashworthiness requirement of fuel tanks is one of the important requirements in helicopter designs. The relations among the protection frame, textile layer and rubber layer of the fuel tank are introduced. Two appropriate FE models are established, one is for an uncovered helicopter fuel tank without protection frame, and the other is for fuel tank with protection frame. The dynamic responses of the two types of fuel tanks impinging on the ground with velocities of 17.3 m/s are numerically simulated for the purpose of analyzing energy-absorbing capabilities of the textile layer and protection frame. The feasibility of the current crashworthiness design of the fuel tank is examined though comparing the dynamic response behaviors of the two fuel tanks.     

Effects of Different Molten-salt on the Synthesis of Hexagonal Barium Ferrite

Hexagonal-plate BaFe12O19 nano-particles were prepared by combining the co-precipitation and molten-salt method. The effects of molten-salt NaCl on the products have been compared with those of KCl. The X-ray diffraction analysis, the environment scanning electron microscopy and the vibrating sample magnetometer were used to measure their characteristics. The results show that the mol- ten-salt KCl is helpful to obtain pure phase while the molten-salt NaCl will prompt the crystallinity of particles to increase. It is also found that, given the molten-salt of NaCl and that of KCl of the same quantity, the particles formed are also the same size. The size of particles slightly increases as the quantity of the salt increases. Moreover, the sample prepared under 200% NaCl salt system has magnetization of 71.5 emu/g.     

Effects of Different Molten-salt on the Synthesis of Hexagonal Barium Ferrite

Hexagonal-plate BaFe12O19 nano-particles were prepared by combining the co-precipitation and molten-salt method. The effects of molten-salt NaCl on the products have been compared with those of KCl. The X-ray diffraction analysis,the environment scanning electron microscopy and the vibrating sample magnetometer were used to measure their characteristics. The results show that the mol-ten-salt KCl is helpful to obtain pure phase while the molten-salt NaCl will prompt the crystallinity of particles to increase. It is also found that, given the molten-salt of NaCl and that of KCl of the same quantity, the particles formed are also the same size. The size of particles slightly increases as the quantity of the salt increases. Moreover, the sample prepared under 200% NaCl salt system has mag-netization of 71.5 emu/g.     

FEM Analysis of Spring-backs in Age Forming of Aluminum Alloy Plates

The age forming technology, characterized by huge spring-backs, has been developed to manufacture large integral wing-skin panel parts, which necessitates devising a method of predicting spring-backs. A 7B04-T7451 aluminum alloy creep test in tension is accomplished at 155 ℃, and the creep curves are obtained. The material constants of the mechanism-based creep constitutive equations are determined through experiments. The age forming process and the spring-backs of 7B04 aluminum alloy plates are analyzed using the commercial finite element software ABAQUS. The effects of plate thickness and forming time on spring-backs are researched. The spring-backs decrease with the increase of plate thickness and forming time. The test results verify the reliability of the finite element method （FEM） analysis.     

A Glimpse of Osaka

I wondered what Japan would be like before my first visit. The following is what I saw in Osaka after a day's tour.Osaka can be reached after two hours' flight. When the plane began to descend, I looked out from the window to see the blue sea water glittering under the sunshine. An artificial island stands along the coast, where an airport is located for planes to take off and land. It is Osaka, Japan's second largest city.Our visit, accompanied by Japanese friends, had a tight schedule.     

Laser Hardening of Metals

The first experiments on hardening metals by laserpeening induced residual compressive stress in the sur-face of metals for improving their resistance to cracking,stress corrosion and fatigue took place more than 30years ago. However, only today, with the development ofhigh-intensity pulse repetitive rate lasers, this methodstarts to compete to traditional peening, which use influ-ence of small metal balls.Laser peening uses pulses with high intensity 109￣1010 W/cm2 [1]. The laser energy abso…     

Wind tunnel investigation of different engine layouts of a blended-wing-body transport

A 2% scale, cruising version of a 450-seat class Blended-Wing-Body(BWB) transport was tested in the China Aerodynamic Research and Development Center’s FL-26 2.4-by-2.4-meter subsonic wind tunnel. The focus of the wind tunnel test was to investigate the aerodynamic performance of the latest BWB transport design, which would also aid in choosing a final engine arrangement in the three most potential engine integration layouts. The wind tunnel model can be tested with and without the nacelle and h...     

Experimental investigation of characteristics of instability evolution in a centrifugal compressor

The stable range of operation for the centrifugal compressor significantly influences the dynamic, economic, and environment-friendly characteristics of power systems. A deep understanding of the characteristics of instability evolution is necessary to improve the compressor stability. A centrifugal compressor equipped with a vaneless diffuser is experimentally investigated using highresponse static-pressure measurements. The results obtained indicate that three typical rotationalspeed ranges ex...     

Effect of Sintering Conditions on Structure of Manganese Zinc Ferrite Powders

The structures of the Mn-Zn ferrites synthesized under different sintering conditions by the sol-gel method were investigated by the X-ray diffraction （XRD） and the scanning electron microscopy （SEM） with focus on two factors： the pre-sintering treatment and the calcining time. The results show that the sintering conditions have significant effects on the structures and the particle size of the Mn-Zn ferrites. Compared with the products without pre-sintering, those pre-sintered at 500℃ have a single phase and no diffraction peaks of Fe2O3 that could be found. The effects of the pre-sintering temperature on the structures of the ferrites were also studied. As a result, 500℃ proves to be the favorite in the pre-sintering treatment. The XRD patterns of the ferrites calcined at 1 200℃ for 6 h will present diffraction peaks of pure crystallization of spinel phase while those for 2 h or 4 h will show peaks of Fe2O3. The SEM also bears witness to well-grown grains of pure Mn-Zn ferrites if calcined for 6 hours.     

Effect of Sintering Conditions on Structure of Manganese Zinc Ferrite Powders

The structures of the Mn-Zn ferrites synthesized under different sintering conditions by the sol-gel method were investigated by the X-ray diffraction (XRD) and the scanning electron microscopy (SEM) with focus on two factors: the pre-sintering treatment and the calcining time. The results show that the sintering conditions have significant effects on the structures and the particle size of the Mn-Zn ferrites. Compared with the products without pre-sintering, those pre-sintered at 500 ℃ have a single phase and no diffraction peaks of Fe2O3 that could be found. The effects of the pre-sintering temperature on the structures of the ferrites were also studied. As a result, 500 ℃ proves to be the favorite in the pre-sintering treatment. The XRD patterns of the ferrites calcined at 1 200 ℃ for 6 h will present diffraction peaks of pure crystallization of spinel phase while those for 2 h or 4 h will show peaks of Fe2O3. The SEM also bears witness to well-grown grains of pure Mn-Zn ferrites if calcined for 6 hours.     

Essential Points of Market Economical Construction and the Principals of Further Reform

ThenewroundofthereformofChinacivilaviationhasbeenstarted.Inrestrospectingthepast,allthedevelopmentdependsgreatlyonreform,suchasthewaytoturnChinacivilaviationintoenterprisesin1980s,themanagementsystemreformofdivisionbetweenadAnnistrahonandenterprises,themanagementdivisionbetweenairlinesandairPortsinthebegirmingof1990s.Asaresult,wecansaythatreformprovidesapoweffolenergytotherapidcontinuousdevelopmentofChinacivilaviation.Intheturnofthecentury.Chinacivilaviationalsomeetswithmanydifficultieswitht…     

An Overview of the 50-Year Development of China's Civil Aviation Industry

OnNov.2,1949,thenewlybomgovemmentofthePeople'sRepublicofChinasetupCivilAviationAdndnistrationofChina(CAAC)underthePeople'sRevolutionaryMilitaryCommission.Forthe50years,Chinahasgrownintotheworldgiantinairtransport.1.FleetConstructionChineSeairlineshadatotalof523COIYnneededinl998,wtl.6timesandl64bomoreha3oedinlosoand78ndinlor8.~anedtalzzrtinlosoanu82edinl978,whileinl998,theaVeragrSeatsofeachedgreWtol6().ThetranpecaPabilityofl998reacanloor8.8tons,wtawas9.2bondl`s.4bowrthaforotl95oanulo…     

Ground-based Investigations of Atomic Oxygen Erosion Behaviors of Silver and Ion-implanted Silver

Silver foils and ion-implanted silver foils exposed to atomic oxygen (AO) generated in a ground simulation facility were investi-gated by the quartz crystal microbalance (QCM), the scanning electron microscopy (SEM) and the X-ray photoelectron spectroscopy (XPS). The experimental results show the presence of Ag2O and AgO in an oxidation process of the silver foil having exposure to AO. As soon as silver comes under the bombardment of atomic oxygen, the oxidation process starts with a thick film forming on the silver surface. Because of the development of stresses, the oxide layer gets cracked and spalled, which leads to appearance of a new silver surface intensifying further oxidation. At last, AgO begins to form on the outer surface of the oxide film. The analytical results of the XPS and the AES attest to formation of a continuous high-quality protective oxide-based layer on the surface of ion-implanted silver films after exposure to AO. This layer can well protect materials in question from erosion.