Search

The key models of flatness analysis method are the strip plastic deformation model (SPDM) and the roll stack elastic deformation model (REDM). The traditional method uses the SPDM to calculate the distribution of rolling force, and the REDM is adopted to calculate the profile of exit strip. The reverse iteration method uses the REDM to calculate the distribution of rolling force, while the SPDM is adopted to calculate the profile of exit strip. The model coupling method integrates SPDM and REDM as one set equations through their internal relation. In this paper, the basic thoughts of three methods are introduced. Through a typical example, the convergence, calculation speed and precision of three different methods are analyzed. It is found that the calculation precision of the three methods are almost the same, but the model coupling method is more outstanding than other two methods on the convergence and calculation speed, so the model coupling method is the best choice for flatness analysis.

SiC single crystal substrate has been become an indispensable substrate material in the field of semiconductor lighting. But, there is no report on the commercial slurry of chemical mechanical polishing (CMP) SiC substrate. In this paper, according to orthogonal design, the composition selection and optimization of CMP slurry based on silica sol (SiO2 abrasive) had been done in CMP SiC crystal substrate (0001) C surface by tests. The CMP slurry based on silica sol for SiC crystal substrate (0001) C surface had been obtained. According to the CMP test results, the material removal rate (MRR) is about 15nm/min and the surface roughness Ra is about 0.2nm.

This paper took the enterprises of make-to-stocking (MTS) as the research object. It introduced the features of MTS enterprises and different forecasting methods. It analyzed the importance of the forecast for Production Planning. With the gray forecasting methods, an appropriate model was established. The model was solved by using the Matlab software. Finally, the results proved the superiority of the gray prediction method by comparing the gray prediction with traditional forecasting methods accuracy. It could be applied in the actual production.

In this paper, according to the slurry ingredients obtained by former research, the influences of the chemical mechanical polishing (CMP) process parameters, such as the rotational velocity of the platen and the carrier, the polishing pressure and the abrasive size on the material removal rate (MRR) and surface roughness Ra have been studied in CMP SiC crystal substrate (0001) C and (0001) Si surface based on the diamond abrasive. The research results show that the material removal rate changes with the change of the abrasive size, the rotational velocity of the platen and the polishing pressure significantly, but the maximum of MRR can be obtained at a certain rotational velocity of platen, abrasive size and polishing pressure. The influence of the abrasive size, the platen velocity, the carrier velocity and the polishing pressure on surface roughness is no significant. Under the same conditions, the MRR of CMP the Si surface is larger than that of the C surface. This study results will provide the reference for optimizing the process parameters and researching the material removal mechanism in CMP SiC crystal substrate.

SiC crystal substrate has been widely applied in the field of semiconductor industry and optical components recently,such as IC and semiconductor lighting. In this paper, according to orthogonal design, the composition selection and optimization of chemical mechanical polishing (CMP) slurry based on alumina (Al2O3) abrasive had been done in CMP SiC crystal substrate (0001) Si surface by a lot of tests. A CMP slurry based on alumina (Al2O3) abrasive for SiC crystal substrate (0001) Si surface had been obtained. According to the CMP test results, the material removal rate (MRR) is about 3 nm/min and the surface roughness Ra is about 0.198μm.

In this work, CoS flowerlike microclusters with well-aligned nanoflakes were synthesized using a facile solution-phase biomolecule-assisted approach in the presence of L-cysteine (an ordinary and cheap amino acid), which turned out to serve as both the S source and the directing molecule in the formation of cobalt sulfide nanostructures. The morphology, structure, and phase composition of the as-prepared CoS products were characterized using various techniques. The formation mechanism for the cobalt sulfide flowerlike assemblies with well-arranged nanoflakes was also discussed. This facile and solution-phase biomolecule-assisted method can be potentially extended to the preparation of other metal chalcogenides including NiS, PbS, MnS, FeS and CuS nanostructures.

The SiC crystal substrate has been widely used in the area of microelectronics, photonics and new materials, such as semiconductor lighting, integrated circuits, and so on. In this paper, the influences of the lapping parameters, such as the rotational velocity of the lapping platen and the carrier and the polishing pressure on the material removal rate (MRR) and surface roughness Ra of SiC crystal substrate (0001) C surface based on the diamond particle in lapping. This study results will provide the reference for developing the abrasive paste, optimizing the process parameters and researching the material removal mechanism in lapping of SiC crystal substrate.

In this paper, multidimensional evaluation model is made to select and analysis the new energy vehicles developing direction, namely to maturity, cost, energy resources, pollution and greenhouse gas emissions, energy efficiency and technical characteristics. And the research results show that, China should take the new energy vehicle technology line with "oil-electric hybrid, pure electric, improved hybrid- hydrogen fuel cell (hydrogen power), rechargeable hybrid" as the main line, and adjustment should be made with the technology innovation, industrial development, conditions and so on.

This paper present a high-speed reconfigurable serial fieldbus (HRSFB) used for industry communication with baud rate up to 10Mbps and reliable communication. We developed this fieldbus based on UART (Universal Asynchronous Receiver/Transmitter) and practice it on FPGA. By using hardware programming on FPGA, we can get the high speed and make the bus reconfigurable easily. This fieldbus system includes one main node and up to 255 sub nodes, and all the nodes can automatically identified and configured at the beginning of the system which makes the field bus system shrink or expand easily. Also hardware CRC technology and ask/answer mode are used in the communication protocol to guarantee the security of the communication. This bus has been widely used in many fields, like PLC controller, CNC machine controller, data acquisition system and so on.

Excessive longitudinal displacement of the girder would emerge in floating system bridge subject to vehicle braking force because of non-restraint in longitudinal direction of the bridge. To reduce it, viscous dampers are set up in longitudinal direction between the girder and the tower of floating system bridge, and the influence matrix method is applied to determine the optimal parameters of viscous dampers. The analysis results of Pingsheng Bridge show that the longitudinal displacement of the girder is relatively large for floating system bridge, and it can be effectively controlled by viscous dampers with optimal parameters obtained by influence matrix method.

Protonation constants of pyrocatechol, pyrogallol and gallic acid, and stability constants, thermodynamic properties of their complexes with tetravalent vanadium VO2+ have been calculated by using pH-potentiometry at different temperatures and ionic strength of 0.1mol•L-1NaCl. The results indicated protonation constants and stability constants decrease with increasing temperature. Higher temperature is unfavorable to the complexation reactions. This kind of reaction is exothermic reaction that was spontaneous. Compared with all thermodynamic properties, the enthalpy change is the driving force for the reaction.

Large longitudinal displacement would be generated by vehicle braking force in the girder of self-anchored suspension bridge, just as the floating system of cable-stayed bridge. In this paper, taking Pingsheng bridge as an engineering example, the vehicle braking force models are established according to traffic survey, furthermore dynamic response and vibration reduction of the bridge under vehicle braking force are investigated by finite element analysis. The results show that the longitudinal displacement of the girder is relatively large, and it can effectively be controlled by viscous dampers with optimal parameters.

Due to the similarities between electrode model and their CNC machining process, process design could be finished efficiently using the electrode automatic classification system as well as the existed standard process template. This study developed an automatic classification retrieval system of electrode model by applying a statistical approach, namely SVM model, to the classification of electrode model, where 3D Polar-Radius Surface Moment was used to extract the feature vector of the electrode model. Experiments showed a promising result with an average classification accuracy up to 85.72% in addition to the high efficiency and usability. Most important, the developed approach is capable of reusing existing knowledge and experience and as a result it makes the CNC programming process easier.

Silver-zinc slag, containing a lot of Bi, Ag, Cu, Zn, Pb and a little Au, has high comprehensive utilization value. This paper describes a preparation method of high-purity nanometer bismuth trioxide (Bi2O3) from silver-zinc slag by hydrometallurgical method. The results showed that Bi could be effectively leached out from silver-zinc slag using sodium chlorate, hydrochloric acid and sodium chloride as leaching agents, and the leaching rate of Bi was up to 99.03% under the optimum conditions. The contents of Pb2+ and Ag+ in BiCl3 solution could be reduced to about 1mg/L by using silver-zinc slag as reductant and sodium iodide (NaI) as precipitant, respectively. Crystalline form of Bi2O3 is affected greatly by concentration of NaOH, conversion temperature and time. The suitable temperature of BiOCl converting to Bi2O3 was 90 , and the suitable surfactant was polyvinyl alcohol. The average particle size of Bi2O3 obtained was about 86 nm, the purity of Bi2O3 was up to 99.75%, and the yield was 98.21%.

Replication of micro structures on a polymer substrate employing two-stage hot embossing is described in this paper. Linear channels with rectangular cross section were fabricated on a master mold of a brass plate by means of a computer numerical control (CNC) machining center using a micro end mill. In the first embossing process, the master mold with concavity features was embossed on a polycarbonate (PC) plate in order to make a “polymer replication mold”. Polytetrafluoroethylene (PTFE) was chosen as a material of polymer substrate used in the second embossing process. The replicated structure on PTFE substrate was observed and each dimension of its cross-sectional shape was also measured in order to assess the replication accuracy. According to the results, it was found that the depth of a replicated channel was near 90 % of that on the master mold. But roundness at each corner could be also found due to the insufficiency of plastic flow. Furthermore the deformation of the structures on a replication mold of PC before and after 2nd hot embossing process was also examined. As a result, it was found that the deformation ratio at temperatures below 145 oC was roughly smaller than 10 %.