Development of Cast Superalloys for Gas Turbines in China

As in other countries,significant achievements in theresearch of cast superalloys for many years have also beenobtained in China.These results are important contribu-tion to the development of aero and land-based gas tur-bine engines.     

Ultrasonic Measurements on Quench—Condensed Noble Gas Films

Quench–condensed noble gas films are a simple model system for studying the elastic properties of polycrystalline or amorphous solids at low temperatures. We have investigated the temperature dependence of the sound velocity v/v and attenuation of quench–condensed polycrystalline Ar, Ne, and HD films using surface acoustic waves at 800 MHz. Up to 0.7 K the sound velocity of all samples increases logarithmically in temperature and decreases above 1 K. This behavior is similar to what is found in glasses and is indicative of the presence of tunneling systems with a wide distribution of energies. Despite the qualitative similarities between the samples, remarkable quantitative differences were observed: Compared to argon the changes of sound velocity and of attenuation in neon are reduced by almost one order of magnitude and in HD even by approximately two orders of magnitude.     

Gas pressure sintering of silicon nitride — current status

Gas pressure sintering of silicon nitride is now common for obtaining a dense as well as tough product. A review of earlier works has revealed that there are still controversies in prediction of mechanism of the sintering process. Analysis of the kinetics of the process obtained by integration of a dilatometer inside the furnace has been presented. The mechanism of sintering silicon nitride powder compacts in presence of hyperbaric nitrogen atmosphere has been discussed. It has been observed that intermediate stage densification kinetics is very much susceptible to sintering atmosphere and time of pressurisation. The microstructure of the final product has been found to be dependent primarily on the method of incorporation of additive in the starting silicon nitride powders.     

The Olympics and Standards——Development of Standardization and Sports in China

The modern Olympic Movement has been con-necting people of different nations,ethnicities andcultural backgrounds in competitive sports,and hasexerted a profound influence on human civilization.As a sports phenomenon,the Olympic Gamesis the most fascinating sports arena in which     

Lean Product Development—Faster,Better … Cleaner?

To address this challenge, lean product development has emerged to become the leading improvement methodology for companies toward the creation of a competitive advantage on innovation and technology leadership. While lean product development has its origin in the best practice studies of Japanese car manufacturers such as Toyota, it has been further elaborated in defence and aerospace organizations over the last two decades, and recently empirical evidence has become available for successful introductions in sectors different from the traditionally-studied environments. The primary purpose of this work is to untangle the fuzziness that still surrounds lean product development and to ground the key aspects of lean product development based on insights from six studies published in a special issue of the Engineering Management Journal on this topic. This demonstrates how better and faster product development can be achieved through the integration of lean principles with the best of more traditional new product development (NPD) practices, into a holistic system that can be characterised by value-focused and risk-based decision making, the socio-technical integration of people and process, improved project, pipeline and portfolio management, optimized knowledge management, and the creation of a learning organization. Unfortunately, while the increasing global competition offers the potential to improve the quality of life for many, the spirit of faster, better, and cheaper also threatens to endanger the future of our planet as a whole. As the majority of a product’s social and ecological impacts are committed in the design phase, it, therefore, seems imperative to investigate the integration of lean product development and eco-design principles. As a result, this work also explores the symbiosis of both approaches through the identification of tools and methods that can support the triple bottom-line goals for a sustainable future of life and business.     

Selection of Modeling Criteria in the Development of Systems for Excitation of the Active Medium for Gas‐Discharge Lasers

It is shown that an algorithm for selection of modeling criteria that lies in isolating the most general features of the objects studied can lead to such investigational methods as methods of dimensional theory and similarity theory. Similarity relations for electrodeless gas discharges are given that are obtained based on the above algorithm. A design technique is presented for a system for excitation of the active medium for CO₂ lasers with pumping by a nonselfmaintained discharge and preionization by an electrodeless pulsed discharge.     

Development of nitrogen-containing nickel-free austenitic stainless steels for metallic biomaterials—review

Metallic biomaterials—such as 316L stainless steel and cobalt-based alloys—have been used as biomaterials mainly because of their excellent mechanical and corrosion properties. However, the release of nickel trace elements—which cause toxicity—has prompted the development of nitrogen-containing nickel-free austenitic stainless steels. This paper reviews their development, traces the history of 316L stainless steel, and the improvement of properties by nitrogen addition. These steels are now available for production of implant devices such as bone plates and screws. Such production requires special techniques with nitrogen absorption treatment.     

Research and Development of a Network—Based Intelligent Maintenance Information System

A maintenance information system is an important part of equipment management.An intelli-gent maintenance information system(IMIS)is a synthesis of network technology,information technology and intelligent technology.The IMIS in used to finish flexible maintenance decision-making and fast main-tenance planning,which helps enterprises to effectively reduce maintenance cost and increase working effi-ciency.Because the IMIS integrates advanced technologies,its performance is better than a traditional one.The difference between an IMIS and a traditional maintenance information system,and the functions,struc-ture,important realizations,and application of an IMIS are discussed in this paper.     

Contributing to Sustainable Development—The Mission and Value of Higher Education

Some notes on sustainable development and scientific outlook on development were given．It is addressed that the mission of higher education to contribute to sustainable development should be reinforced and further expanded．The present situation of China’s higher education and the improvements required were analyzed．Two modes of thinking（reductionism and holism）and the relationship between the mode of thinking and the mode of development were discussed．The change in the mode of thinking is the key point for Chinese higher education,and more intensive reform of teaching affairs is necessary．A proposal of the revision of China’s Higher Education Act and University Constitutions was put forward．     

Gas pressure sintering of β-silicon nitride

The sintering behaviour of -Si₃N₄ powder was investigated in 980 kPa (10 atm) nitrogen at 1800–2000 °C. It is shown that -Si₃N₄ has a higher sinterability than the finer -Si₃N₄. The solution of small grains and reprecipitation on large grains occurred during sintering at >1600 °C. The rate-determining step in the liquid-phase sintering is believed to be the diffusion of material through the liquid phase at grain boundaries. There was no abnormal grain growth during gas pressure sintering of -Si₃N₄. The microstructures of gas pressure sintered materials from -Si₃N₄ were more uniform than those from -Si₃N₄. The densification mechanism of -Si₃N₄ is discussed in relation to that of -Si₃N₄.     

Development of porous zirconia spheres by polymerization-induced colloid aggregation — effect of polymerization rate

Polymerization-induced colloid aggregation is used to synthesize spheres of narrow size distribution which are porous aggregates of ZrO₂ colloids. Variation of the reaction pH has been investigated to determine the optimum rate of polymerization of the urea-formaldehyde resin. At the optimum rate, a colloid packing structure is formed where a balance of high porosity and high strength of the aggregates is achieved. This optimum coincides with the maximum yield of the 5 m sintered (polymer-free) particles. Particles synthesized at pH values below the optimum are mechanically weak; some are hollow spheres. Variation of the pore structure, and thus colloid packing structure, is elucidated by nitrogen adsorption and apparent density measurements. Differences on either side of the optimum pH are related to the efficiency of polymer-bridge formation between colloids.     

CCC Certification Promotes Sound Development of Chinese Economy——On the establishment of China Certification and Accreditation Association

On Sept.27,2005,China Certification and Accreditation Association was set up,which was a sign of standardization and legalization for China certification and accreditation.Furthermore,its main task includes supporting fairness,gain- ing credit,promoting development and building a harmonious society.     

Thermodiffusion in a Hydrogen–Nitrogen Gas System

Characteristics of thermodiffusion molecular mass transfer of a binary frozen hydrogen–nitrogen gas mixture are predicted by the method of entropy similarity. Calculations are made within a wide range of variation of temperatures and concentrations at normal pressure.     

A Novel Multiple Component Gas Infrared Ray Sensor

1　IntroductionInfraredgasanalyzer(IGA)hasbeenwidelyappliedinseismforecast,minesecurity ,petroleumreconnaissance ,atmospherephysics,medicaltreatment,andpollutionsourcemonitoring,highvoltagefacilitydiagnostics ,chemicalin dustrysurveillanceandmetallurgyaswellasallnewtechnol ogyareasuchasbioscience ,micro electronicsandnewma terial.InthefutureIGAtechnicaltrendsaremultiplecom ponentgastestedsynchronously ,intelligentizedoperationandlowercost[1,2 ] .Atpresent,scholarsallworldhavedonemuchworktoan…     

Sensitivity to Combustible Gas for ZnO Thin Films

A fine polycrystalline ZnO thin film with 0.3～0.6 μm grain size was obtained by sol-gel process and a consequential heat treatment at 500℃. The process of preparing ZnO thin film was analysed. The sensitivity and conductivity of ZnO thin films as combustible gas (CO, CH4,H2) sensor as well as the influence of catalyst and pH value of the precursor on its sensitivity were studied in detail. The structure characteristics of ZnO thin film by different process were irlvestigated by X-ray diffraction, thermal analysis and photoelectron spectrometer. The atomic ratio of Zn to O on the surface of ZnO thin film was found to be 1.14:1 measured from XPS result. The conductivity of the thin film increases greatly when doped with Al3+ ion but decreases while doped with Na+ ion     

Gas Sensing Based on a Nonlinear Response: Discrimination between Hydrocarbons and Quantification of Individual Components in a Gas Mixture

A novel sensing system is proposed based on the multidimensional information contained in a dynamic nonlinear response. A sinusoidal temperature change was applied to a SnO(2) semiconductor gas sensor, and the resulting output conductance of the sensor was analyzed by fast Fourier transformation (FFT). The higher harmonics of the FFT characterized the nonlinear properties of the response. The amplitudes of the higher harmonics of the FFT exhibit characteristic changes which depend on the chemical structure, concentration, and the kinetics of adsorption and the reaction of hydrocarbon gases and aromatic vapors on the sensor surface. In addition, it is possible to distinguish between gases in a gaseous mixture with a single detector using this dynamic nonlinear response. Nonlinear responses are discussed in relation to the kinetics of the reaction at the sensor surface and the temperature-dependent barrier potential of the semiconductor.     

Study on Fine Structure of Gas Atomized LaNis-based Alloys

The fine structure of hydrogen storage alloy powders MlNi4.3-xCoxMn0.4Al0.3(x=0.75, 0.45, 0.10; Ml: La-rich misch metal) prepared by rapidly solidifying gas atomization was investigated using a Rietveld analysis method. Two sets of CaCus-type crystal constants were observed in the studied alloys and one set was larger than the other. With decreasing powder radius the solidification rate of powder increased, and so did the percentage of a particle part with larger crystal constants. The reason why there were two sets of crystal constants might be the difference of solidification rate between the outside and inside of a particle.     

Critical Behavior of 2 − Ions in Argon Gas

We measured the drift mobility of ₂ ^– ions in argon gas close to the critical point for (1.005 < T/T _c < 1.04) above T _c 150.7 K in the density range (0.025 <N/N _c< 1.733) around the bulk critical density N _c = 8.08 atoms . nm^–3. The density-normalized zero-field mobility ₀ N of the ions shows a deep minimum as a function of the gas density N as T T _c ⁺ This anomalous reduction of ₀ N occurs at a density N _m 0.76N _c. We believe that this behavior is due to the strong electrostriction exerted by the ion on the highly compressible gas. By introducing suitable contributions to the effective ion radius R due to the large gas compressibility and taking into account short-range local density and viscosity augmentation due to electrostriction, the hydrodynamic Stokes formula ₀ = e/6R, where is the gas viscosity, is in good agreement with the experimental data.     

Development of Advanced Cement-Based Building Products

In this study, short fiber-reinforced cement-based building products of sheets, pipes and honeycomb panels incorporating various mineral admixtures such as slag, silica fume, and metakaolin have been developed by the extrusion technique. The experimental works have shown that these products do have very good mechanical properties. Since the key point for a successful extrusion is the properly designed rheology which controls both internal and external flow properties of ext rudate, a nonlinear viscoelastic model was applied to investigate the rheology behavior of a movable fresh cementitious composite in a single screw extruder channel. The theoretical analysis is used to guide the practical manufacturing.