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1.
Alumina nanoparticles （A1NP） were synthe- sized from aluminium nitrate using extracts of tea, coffee and triphala--a well known herbal plant as well as a non- toxic and eco--friendly green material. The synthesis was carried out taking 1：4 ratio of metal salt and these extracts under microwave irradiations at 540 W, which gave better yield of nanoparticles. Water was taken as solvent medium. The formations of A1NP were initially monitored by the colour changes occurring in the reaction mixture during the incubation period. As synthesized nanoparticles were characterized by scanning electron microscope （SEM）, UV-Visible （UV-Vis） spectroscopy and Fourier transform infrared spectroscopy （FTIR）. The A1NP were found to be spherical in shape in case of tea and coffee extracts with a size of 50-200 nm and to be oval shaped in case of triphala extract with an average size of 200-400 nm. The formation of A1NP with the microwave-assistance using these plant extracts has proved to be very faster than any other methods. In addition, excellent reproducibility of these nanoparticles, without the use of any additional capping agent or stabilizer will have great advantages in compari- son with microbial synthesis, avoiding all the tedious and hygienic complications. 相似文献
2.
Machining titanium is one of ever-increasing magnitude problems due to its characteristics such as low thermal conductivity, modulus of elasticity and work hardening. The efficient titanium alloy machining involves a proper selection of process parameters to minimize the tangential force （Fz） and surface roughness （Ra）. In the present work, the performance of PVD/TiA1N coated carbide inserts was investigated using response surface methodology （RSM） for turning Ti-6A1-4V. The effects of process parameters such as speed （v）, feed （/＇）, depth of cut （d） and back rake angle （Ty） on Fz and Ra were investi- gated. The experimental plan used for four factors and three levels was designed based on face centered, central composite design （CCD）. The experimental results indi- cated that Fz increased with the increase in d, f and decreased with the increase in v and yy, whereas Ra decreased with the increase in v and 7y, and increased with d and v. The goodness of fit of the regression equations and model fits （R2） for Fz and Ra were found to be 0.968 and 0.970, which demonstrated that it was an effective model. A confirmation test was also conducted in order to verify the correctness of the model. 相似文献
3.
Deviation values of specific heat difference ACp, the Gibbs free energy difference AG, enthalpy dif- ference AH, and entropy difference AS between the supercooled liquid and corresponding crystalline phase produced by the linear, hyperbolic, and Dubey＇s expres- sions of ACp and the corresponding experimental values are determined for sixteen bulk metallic glasses （BMGs） from the glass transition temperature Tg to the melting temperature Tm. The calculated values produced by the hyperbolic expression for ACp most closely approximate experimental values, indicating that the hyperbolic ACp expression can be considered universally applicable, compared to linear and Dubey＇s expressions for ACp, which are accurate only within a limited range of condi- tions. For instance, Dubey＇s ACp expression provides a good approximation of actual experimental values within certain conditions （i.e., ~ = ACg/AC~ 〈 2, where ACpg and ACp represent the specific heat difference at temperatures Tg and Tm, respectively）. 相似文献
4.
Tandem rapid manufacturing of Inconel-625 using laser assisted and plasma transferred arc depositions 总被引：1，自引：0，他引：1
P. Bhargava C．P．Paul C．H．Premsingh S．K．Mishra AtulKumar D．C．Nagpure GurvinderjitSingh L．M．Kukreja 《上海大学学报(英文版)》2013,(4):305-313
This paper presents an investigation on depo- sition of Inconel-625 using laser rapid manufacturing （LRM） and plasma transferred arc （PTA） deposition in individual and tandem mode. LRM has advantages in terms of dimensional accuracy, improved mechanical properties, finer process control, reduced heat input and lower thermal distortion, while PTA scores more in terms of lower initial investment, lower running cost and higher deposition rate. To quantify the clubbed advantages and limitations of both processes, these were studied individually and in tandem. A number of samples were deposited at different process parameters like power, scan speed, powder feed rate. They were subjected to tensile test, adhesion-cohesion test, impact test and micro hardness measurement. The results of individual tests showed the comparable mechanical prop- erties with i20% variation. The mixed dendritic-cellular and dendritic-columnar microstructures were respectively observed for LRM and PTA deposits with a distinct inter- face for the case of tandem deposition. The interface strength of tandem deposits was evaluated employing adhesion-cohesion test, and it was found to be （325 i 35） MPa. The study confirmed the viability of LRM and PTA deposition in tandem for hybrid manufacturing. 相似文献
5.
The cellular manufacturing （CM） has been proved as a well-known manufacturing strategy that helps to improve manufacturing efficiency and productivity by utilizing the philosophy of group technology. Large num- ber of papers has been published in the area of design issues of CM system. Unfortunately, the issues related to acceptability of CM in Indian industries are typically not examined rigorously as technical issues. This paper pre- sents the results of a survey carded out to find the status, enabler and barrier of implementing CM system in Indian industries. 相似文献
6.
Gas metal arc welding （GMAW） develops an arc by controlling the metal from the wire rod and the input pro- cess parameters. The deposited metal forms a weld bead and the mechanical properties depend upon the quality of the weld bead. Proper control of the process parameters which affect the bead geometry, the microstructures of the weldments and the mechanical properties like hardness, is necessary. This experimental study aims at developing mathematical models for bead height （HB）, bead width （WB） and bead penetration （PB） and investigating the effects of four process parameters viz： welding voltage, welding speed, wire feed rate and gas flow rate on bead geometry, hardness and microstructure of AISI321 steel with 10 mm thickness. The transient thermal analysis shows temperature and residual stress distributions at different conduction and convection conditions. 相似文献
7.
The relationship between bilayer nanostructure, defect density and dye-sensitized solar cell （DSCC） per- formances was investigated. By adjusting bilayer nano- structures, defect density of ZnO nanodendrite-nanorods structure was decreased comparing to that of nanoflower- nanorods structure. The performances of DSCC based on ZnO nanodendrites-nanorods structure and nanoflower- nanorods structure were studied by Raman spectrum, room temperature photoluminescence, dye loading, photocurrent density-voltage characteristic and open-circuit voltage decay （OCVD） technique. The device with nanodendrite- nanorods structure has lower charge recombination rate and prolonged electron lifetime due to its microstructure feature. 相似文献
8.
Min Jiang ;Li-Na Chen ;Jin He ;Guang-Yao Chen ;Chong-He Li ;Xiong-Gang Lu 《上海大学学报(英文版)》2014,(3):265-274
The study of controlled rolling/controlled cooling process parameters which affect the microstructure and mechanical properties of a novel pipeline steel has been optimized by the orthogonal experiment with four factors and three levels in this paper. However, the parameters of thermo-mechanical control process （TMCP） optimized by the Gleeble-3500 hot simulator could not satisfy performance requirements of the X100 pipeline steel. In order to improve the performance of this steel, the influence of finish cooling temperature （FCT） on the microstructure and property is studied in detail. It is found that, as this steel is thermo-mechanically treated by this set of parameters （the start heating temperature, finish rolling temperature （FRT）, FCT and cooling rate of 1,180 ℃, 810 ℃, 350 ℃ and 35 ℃/s, respectively）, the micro- structures are mainly composed of granular bainite （GB） and acicular ferrite （AF）. The effective grain sizes are below 20 μm; the steel reaches the optimal balance between the strength and the toughness; the yield strength is 695 MPa; the tensile strength is 768 MPa; the elongation is 16.6 %; the impact energy is 262 J at room temperature. All indexes could meet the requirements of X100 pipeline steel. 相似文献
9.
H. Xu T. Suni V. Vuorinen J. Li H. Heikkinen P. Monnoyer M. Paulasto-Krockel 《上海大学学报(英文版)》2013,(3):226-235
Hermetic packaging is often an essential requirement to enable proper functionality throughout the device＇s lifetime and ensure the optimal performance of a micro electronic mechanical system （MEMS） device. Solid-liquid interdiffusion （SLID） bonding is a novel and attractive way to encapsulate MEMS devices at a wafer level. SLID bonding utilizes a low-melting-point metal to reduce the bonding process temperature; and metallic seal rings take out less of the valuable surface area and have a lower gas permeability compared to polymer or glass- based sealing materials. In addition, ductile metals can adopt mechanical and thermo-mechanical stresses during their service lifetime, which improves their reliability. In this study, the principles of Au-Sn and Cu-Sn SLID bonding are presented, which are meant to be used for wafer-level hermetic sealing of MEMS resonators. Seal rings in 15.24 cm silicon wafers were bonded at a width of 60 gin, electroplated, and used with Au-Sn and Cu-Sn layer structures. The wafer bonding temperature varied between 300 ℃ and 350 ℃, and the bonding force was 3.5 kN under the ambient pressure, that is, it was less than 0.1 Pa. A shear test was used to compare the mechanical properties of the interconnections between both material systems, in addition, important factors pertaining to bond ring design are discussed according to their effects on the failure mechanisms. The results show that the design ofmetal structures can significantly affect the reliability of bond rings. 相似文献
10.
Abstract The compliance of an integrated approach, principal component analysis （PCA）, coupled with Tagu chi＇s robust theory for simultaneous optimization of cor related multiple responses of wire electrical discharge machining （WEDM） process for machining SiCp rein forced ZC63 metal matrix composites （MMCs） is investi gated in this work. The WEDM is proven better for its efficiency to machine MMCs among others, while the particulate size and volume percentage of SiCp with the composite are the utmost important factors. These improve the mechanical properties enormously, however reduce the machining performance. Hence the WEDM experiments are conducted by varying the particulate size, volume fraction, pulseon time, pulseoff time and wire tension. In the view of quality cut, the most important performance indicators of WEDM as surface roughness （Ra）, metal removal rate （MRR）, wire wear ratio （WWR）, kerf （Kw） and white layer thickness （WLT） are measured as respon ses. PCA is used as multiresponse optimization technique to derive the composite principal component （CPC） which acts as the overall quality index in the process. Consequently, Taguchi＇s S/N ratio analysis is applied to optimize the CPC. The derived optimal process responses are confirmed by the experimental validation tests results. The analysis of vari ance is conducted to find the effects of choosing process variables on the overall quality of the machined component.The practical possibility of the derived optimal process conditions is also presented using SEM. 相似文献
11.
王瑞涛 《兰州石化职业技术学院学报》2010,10(3):18-20
采用正交试验法,选用L934正交表,以氦检漏泄漏率作为考核指标,对影响焊接效果的电压、脉宽、离焦量和转速四个因素进行试验研究,最终优选的工艺参数组合为A3B2C1D2,即电压为36档,脉宽为3.5ms,离焦量为+1.0mm,转速为3/7r/min。此方法对其它工艺参数的优化研究具有指导和推广意义。 相似文献
12.
Knut E. Aasmundtveit Bao Quoc Ta Quoc-Huy Nguyen Tormod B. Haugen Nils Hoivik Einar Halvorsen 《上海大学学报(英文版)》2013,(3):218-225
The integration of nanomaterials such as carbon nanotubes （CNTs） into microsystems is highly desirable, in order to make use of the unique nanomaterial properties in real devices. However, the CNTtomicrosystem integration is challenging to implement in a manufacturable, cost effective industrial process. This paper presents our work towards a process for making complete, integrated CMOS / MEMS systems with integrated CNT. We demonstrate the feasibility of the process, using roomtemperature process ing, lowcost equipment and consumables, and electrical control with automation possibilities. CNTs are directly integrated at the desired positions in the Si microsystem, forming closed Si / CNT / Si circuits. We explore different designs with the aim to obtain uniform and welldefined CNT synthesis conditions, and show that simplified designs can perform comparably to more complex ones. The Si / CNT / Si circuits obtained can show rectifying （Schottky like） or nearohmic behavior. Gas sensing possibilities are demonstrated, indicating the possibility of monitoring aging/ fermenting of food. Functionalization of CNTs is demon strated, using thermal evaporation of Sn and Pd, opening for selective and sensitive sensors for various gases and ana lytes. Detailed microscopic characterization of the obtained CNTs are presented. 相似文献
13.
雷玉勇 《重庆大学学报(英文版)》2003,2(1)
1. Introduction With the development of transportation, more and more road tunnels, especially the long tunnels, such as Erlangshan Tunnel (4176 m, China), Arlberg Tunnel (13972 m, Austria), Kan-etsu Tunnel (11055 m, South tube, Japan) and Laerdal Tunnel (24510m, Norway) have been built on the highway lines [1]. In a road tunnel, the exhaust gases given off by automobile engines, such as smoke, carbon monoxide (CO), oxynitride (NOx), hydrocarbon, etc., and dust produced by the passing a… 相似文献
14.
利用方波伏安法研究了尿酸在聚甘氨酸修饰玻碳电极上的电化学氧化行为.结果表明:在0.01 mol/L磷酸盐缓冲液(pH=7)中,尿酸在+0.31 mv左右产生一个氧化峰,峰电流与尿酸在1.0×10-6—1.0×10-5mol/L浓度范围呈较好的线性关系,相关系数为0.9945.该方法可用于直接测定人体尿酸,回收率为95.5%-104.1%,相对标准偏差为1.4%. 相似文献
15.
利用在线推扫富集技术建立了毛细管电色谱测定新药那格列奈中痕量杂质的方法．考察了缓冲溶液pH值、SDS浓度、运行电压以及进样时间对富集效果的影响．结果表明，那格列奈中的痕量组分富集和检测的最佳缓冲溶液组成为16mmol／L NaH2PO4 6mmol／L Na2B4O7 60mmol／L SDS(pH=7．14)，进样时间为200秒．在最佳条件下对那格列奈进行了痕量杂质测定，那格列奈中的杂质总含量为0．56％．本方法可用于药物的质量控制。 相似文献
16.
在镧离子掺杂类普鲁士蓝（La-PB）修饰的玻碳电极表面电沉积汞膜,制备了一种新型化学修饰复合汞膜电极La-PB/MFE/GC;研究了修饰层厚度、镀汞方式和汞膜成长过程对复合汞膜形成的影响;并以Pb2＋为探针离子,对镧、钴离子掺杂类普鲁士蓝复合汞膜电极和常规玻碳汞膜电极的汞膜稳定性和金属离子的溶出伏安行为等进行了对比研究;同时,应用该电极结合示差脉冲阳极溶出伏安法对实际水样中微量Pb2＋的质量浓度进行了测定.结果表明,Pb2＋在该复合汞膜电极上的阳极溶出氧化峰电流在4.82×10-9～4.82×10-7mol/L范围有良好的线性关系（r=0.995 5,n=13）,检出限为9.06×10-10mol/L,RSD值为2.6%,加标回收率为97%～102%.可用于实际样品的测定. 相似文献
17.
Decomposition of dimethyl sulfide （DMS） in air was investigated experimentally by using a wire-cylinder dielectric barrier discharge （DBD） reactor at room temperature and atmospheric pressure. A new type of high pulse voltage source with a thyratron switch and a Blumlein pulse-forming network （BPFN） was adopted in our experiments. The maximum power output of the pulse voltage source and the maximum peak voltage were 1 kW and 100 kV, respectively. The important parameters affecting odor decomposition, including peak voltage, pulse frequency, gas flow rate, initial concentration, and humidity, which influenced the removal efficiency, were investigated. The results showed that DMS could be treated effectively and almost a 100% removal efficiency was achieved at the conditions with an initial concentration of 832 mg/m3 and a gas flow rate of 1000 ml/min. Humidity boosts the removal efficiency and improves the energy yield （EY） greatly. The EY of 832 mg/m3 DMS was 2.87 mg/kJ when the relative humidity was above 30%. In the case of DMS removal, the ozone and nitrogen oxides were observed in the exhaust gas. The carbon and sulfur elements of DMS were mainly converted to carbon dioxide, carbon monoxide and sulfur dioxide. Moreover, sulfur was discovered in the reactor. According to the results, the optimization design for the reactor and the matching of high pulse voltage source can be reckoned. 相似文献
18.
Mohism as well as Confucianism is a distinguished school in the Spring-Au- tumn and Warring States Periods. But Mozi＇s thought mainly reflects interests and desires of the labor people. He thinks that selfish is the root of social disorder and pain. He puts forward ＂universal loving and multilateral benefiting＂ as a solution. He also contends to build the political centralized monarchy and appoint the good men and able men to office. From the interests and wishes of the producer, Mo Zi critiques the ruler＇s profligate be- havior and Confucian viewpoint of luxuriant burial and long funeral. His standpoint is thrift and simplicity in funerals. 相似文献
19.