最新刊期
卷 38 ， 期 5 ， 2006
- 摘要：Abstract:The research development of RE type and V-Ti based hydrogen storage alloys and Ni/MH batteries, applying predominant resources of RE, V and Ti in Sichuan province, made by the colleagues in the school of materials science and engineering of Sichuan University, were introduced. After years of work, the following achievements were obtained: 1) A series of Nd-free hydrogen storage alloys were developed, and Ni/MH batteries made from them show excellent comprehensive performance both under room and low temperatures. For example, these kinds of batteries applied in the electric bicycles discharge more than others under -30 ℃. 2) Low temperature hydrogen storage alloys and broad temperature range (–40 ℃~+55 ℃) Ni/MH batteries with excellent properties were successfully developed. It is of significance to national defense, frigidity areas and special industries.3) A series of V-Ti-Cr-Fe hydrogen storage alloys with eminent absorption and desorption properties were successfully developed, in which cheap intermediate alloy 80VFe was introduced. Thus the problem of the high cost brought by pure V was solved. This kind of materials is promising to be the hydrogen carrier in fuel cells on board. 4) It is demonstrated that temperatures and Pd affect greatly on the discharge capacities of V. It indicates that this kind of alloys is promising to become the negative materials of primary or secondary Ni/MH batteries with high energy density at or below 80 ℃. The above successful development of Nd free hydrogen storage alloys is important to solve partly the problem of the unbalance application of the rare earth resources, which exists there for a long time in China.
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发布时间：2023-11-28 - 摘要：Abstract:After the impoundment of the Three Gorges Reservoir since June of 2003, The water quality of Three Gorges Reservoir has been focused worldwide. This paper summaried research findings of the water pollution control for the Three Gorges Reservoir and proposed the further research orientations of importance. Finally, the water pollution prevention plan for the Three Gorges Reservoir area and upstream being implemented was reviewed.关键词：Three Gorges Reservoir;water pollution;water quality protection
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发布时间：2023-11-28 - 摘要：Abstract:Proanthocyanidins (PCs), which is widely distributed in plants, is a kind of valuable natural products. The constituents, structures, chemical properties and physiological activities of PCs have been systemically investigated in recent 20 years. It has been revealed that the PCs has multiple biological activities, such as anti-oxidation, scavenging of free radicals, inhibiting of enzymes, protecting of blood vessel, anti inflammation and repressing of tumors, and can be extensively utilized in food, cosmetic, health product and medicine industries. In this paper, the chemical principals for utilization of PCs and the progress on research and utilization of PCs were summarized and discussed based on literatures and the authors’ researches.关键词：proanthocyanidins;plant polyphenols;fine chemicals;anti-oxidation;scavenging of free radical;biological activity
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发布时间：2023-11-28 - 摘要：Abstract:In this review, some valuable results about polypropylene/layered silicate nanocompsites in our group have been briefly depicted. These research subjects involve: 1) mechanism of shear-induced morphological development and exfoliation of layered clay particles during practical molten compounding; 2) effect of mesoscopic clay network on the retarded motion and relaxation of polymer macromolecular chains, and on the macroscopic properties of nanocomposites; 3) unique hierarchical structure of dispersion and orientation in the injection-molded bars obtained via dynamic packing injection molding, which would exert oscillatory shear on the melt of composite during solidification and cooling stage.关键词：nanocomposite;exfoliation;clay network;hierarchical structure
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发布时间：2023-11-28 - 摘要：Abstract:Using abounding bio-resources of West China to develop biodiesel meets the requirements of State Energy Policy and Sustainable Development Strategy. The article analyzed the importance and possibility to develop biodiesel in West China, and also discussed the available material resources of biodiesel production in detail. It is suggested that west area is suitable and potential to develop biodiesel. Based on an extensive discussion on the biodiesel production technologies, the paper discussed the characters of the biodiesel processes from different oil materials. It was suggested that production technologies must be developed to adopt the different material oil/fats in west area. In order to increase the competitive ability, up grade of by product and production of high value side products should be planed in the biodiesel production.关键词：biodiesel;West China;renewable energy resources
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发布时间：2023-11-28 - 摘要：Abstract:In the global economy environment, the competition of mechanical product manufacturing is essentially the competition of mechanical product design. How to develop quickly mechanical product is an important question of improving competition capability of manufacturing industry. It is necessary to study modern design theory, methodology and application technology of mechanical products. Analyzing in face of changes and requirements of mechanical product development, the architecture is proposed for describing modern design theory and method. According to stare of the art and features of the network based modern design methodology, the concept, technical method and main research contents are discussed on the intelligent design and the collaborative design. Several research progresses are introduced, which deal with the representation method of design knowledge, knowledge discovery technology of mechanical design, knowledge warehouse technology, functional architecture of knowledge warehouse for mechanical product, distributed collaborative design principle in the network environment, collaborative design method based on multi agents and so on. Based on development requirements of manufacturing enterprises during the eleventh five years plan of China, we pointed out the eight critical research issues and development trends on the intelligent design based knowledge, design method based resource conservation, computer aided innovation design principle and so on. It has important theoretical guidance significance for studying the modern design theory and methodology oriented information age.关键词：mechanical product design;design methodology;intelligent design;collaborative design;knowledge discovery;knowledge warehouse
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发布时间：2023-11-28 - 摘要：Abstract:Brazilian disc specimen is widely used in mechanical testing for geomaterials Modified Brazilian disc specimen overcomes the shortcoming of stress concentration caused by concentrated loading. Orthotropic material is a generalization of isotropic material. It is in this background that the displacement formula of flattened Brazilian disc for orthotropic material is proposed. Then the finite element software ANSYS is used to simulate the orthotropic flattened Brazilian disc specimen subjected to diametrical compression, the accuracy of the approximate formula of compression displacement is checked. The formula is further modified with a semi empirical and semi-analytical approach,and it is shown to have better accuracy than the original formula covering the whole range of orthotropic anisotropic index of rock, the error is less than 6%.Finally, the application of this displacement formula is introduced with an example, that is by recording the load-displacement plots of flattened Brazilian disc specimens loaded in two orthotropic directions and in two loading angles, respectively, the elastic constants, including two Young’s modulus, two Poisson’s ratios and the shear modulus, of an orthotropic material can be determined by the inverse slope of the straight line of the plots.关键词：orthotropic;orthotropic anisotropic index;flattened Brazilian disc;diametrically compression;displacement formula
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发布时间：2023-11-28 - 摘要：Abstract:Inertia weight model based on Particle Swarm Optimizer is introduced.The basic theory of PSO and calculation steps are illustrated. PSO is applied to the operation of a reservoir in flood conditions on the upper reaches of the Nanpan River. The results are reasonable and meet the requirements of flood scheduling. It is shown that PSO can be applied well to flood control scheduling of reservoir.关键词：particle swarm optimization;inertia weight model;flood control scheduling of reservoir
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发布时间：2023-11-28 - 摘要：Abstract:The paper is based on long series hydrologic data and the percentage of forest cover change data about Chuxiong hydrometric station and Xiaohuangguayuan hydrometric station of Longchuanjiang gorge. Wavelet analysis and statistical analysis are used to study on the interrelation among precipitation、vegetation and runoff variation, and they are also used to study the essence and generation system about quasi periodic change of different timescale runoff volume. The result indicate that the study region's precipitation series exists 2 a、4 a and 14.5 a quasi-prime period, runoff volume series exists 2 a、4 a、6 a and 22 a quasi-prime period, among them, runoff volume's low frequency oscillation reflects the quasi periodic variation about the runoff comes from soil and the groundwater runoff exists in rifts, high frequency oscillation reflects the quasi periodic variation about the surface runoff. Seasonal variation and annual high frequency oscillation of runoff are mainly caused by precipitation change. Runoff series' quasi-prime period around 6 a and 22 a is owing to the forming of soil and rifts' magnifing the precipitation series 4 a and 14.5 a prime period, runoff series' 4 years quasi period is formed by the special physical geographical environment. There is a sudden change of relationship between runoff and precipitation in 1969.关键词：upstream of the Changjiang River;Yuanmou dry-hot valley area;deforestation;precipitation;runoff volume;wavelet analysis;quasi-priod
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发布时间：2023-11-28 - 摘要：Abstract:Xiluodu power station will discharge cold water to downstream in spring after operation and influence the fish breeding at downstream. Modification of the reservoir operation curve is studied to reduce this impact. Three kinds of operation curves are supposed. 2-D laterally averaged k–ε temperature model is adopted to study the water temperature structure in reservoir and the outflow temperature. The result shows during the temperature lifting time from January to June, the increase of the flow discharge will accelerate the decrease of the water level, which will raise the water temperature on the surface and cause the thermocline moving down to the bed. Then more warm water will be led from the surface to the outlet, and the downstream water temperature will rise. The reservoir operation could reduce and avoid the impact of cold water on fish breeding to some degree.关键词：water temperature;reservoir operation;2-D laterally averaged temperature model
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发布时间：2023-11-28 - 摘要：Abstract:The flow pattern is very complex in the plunge pool with multi-submerged jets plunging into it. Around each jet, there are a lot of back-flow swirls near the water surface and cross rod eddies close to the bottom; besides, vertical-axis eddies may appear between two jets. To research the hydraulic characteristics and occurring mechanics and whether the vertical axis eddies can reach the bed, experiments, theories and numerical simulation are applied in this paper. The results show that the vertical axis eddies near the plunge pool bed are caused by the interaction of the 3-D violent turbulent and boundary conditions; the vertical-axis eddies are often random and unsteady. They can not reach the bed, and will gradually disappear with the formation of the cross rod eddy, however, their potential damage need to be further studied.关键词：multiple submerged jets;plunge pool;cross rod eddy;vertical-axis eddy
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发布时间：2023-11-28 - 摘要：Abstract:Determination of the location of phreatic surface in seepage flow can be categorized as solving the problem on free surface. Most of the traditional methods used to determinate the free surface profile are based on modifying or changing the grid system to adapt the changing water surface during the iteration process. The method of free surface adapting grid system presented in this paper doesn't need to modify or change the grid system, whereas it maps free surface to grid nodes to determinate the final phreatic surface in certain precision. This method has such advantages as: easy to apply, convenient to programme, good precision,etc.. The precision of this method can be further improved, if dense mesh system or higher order mapping method is adopted.关键词：seepage flow;phreatic surface;grid mapping
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发布时间：2023-11-28 - 摘要：Abstract:Pre-tensioned cables have been extensively used to reinforce soil and rock slopes. In this paper, the kinematic approach of limit analysis is used to analyse the stability of soil slopes reinforced with pre tensioned cables. The action of a cable is simplified as a force acting on the surface of slope, and formulas are derived to calculate the safety factor of cable reinforced slope. The presence of cable changes the critical surface of reinforced slope. The assumption that the critical surface does not change with the addition of the cable would lead to non-conservative results for the factor of safety. According to analysis results, the most suitable location of the cable within the slope is near the slope toe.关键词：slope stability;pre-tensioned cable;limit analysis;shear strength reduction technique
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发布时间：2023-11-28 - 摘要：Abstract:To reduce the harm of reservoir pollution accident and offer an available suggesting for the managers, it is very important to study the outflow of the pollutant in reservoir. Based on the solution of the 3-D pollutant transportation equation and analysis of hydrodynamics characteristics of the water near the outflow, this article makes a systematic study on the impacts of the vertical position of outflow on the discharging of pollutant in reservoir. It is found that impacts of the vertical position of outflow on the discharging of pollutant are different in different conditions. They rely on the pollutant's vertical distributing near the outflow.关键词：vertical position of outflow;discharging of pollutant in reservoir;study and application
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发布时间：2023-11-28 - 摘要：Abstract:Based on the second law of thermodynamics, it was stated in this paper that the thermodynamic essential of cleaner production is to control the conversion of matters from order to random in the most beneficial way. The efficiency can be indicated by the entropy production in the process. Adopting the principle of minimum entropy production in a steady process of a complex system, a simplified methodology was deduced to calculate the entropy production for complex chemical processes based on the information of mass and heat flux exchanged between the system and environment. A indicator of entropy production was proposed to evaluate the thermodynamic impact of a process by the ratio of total process entropy production to the entropy contained in the valid products. A pair of practical processes of phosphate compound fertilizer, in which sulfur and ammonia are used as energy carrier respectively, were chosen to be calculated and compared. The indicator of entropy production is 6.753 for the sulfur route and 4.571 for the ammonia route. It becomes clearer that the sulfur route makes more thermodynamic impacts to the environment because the matter of sulfur is discharged as waste while the matter of ammonia conversed to the valid products of compound fertilizer.关键词：indicator of entropy generation in chemical engineering;evaluation of cleaner production;phosphate compound fertilizer
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发布时间：2023-11-28 - 摘要：Abstract:To probe the fungal communities in fermented grains, clone analysis and phylogenetic tree of 18S rDNA fragments were taken after using PCR amplification on samples of the fungal community in center of fermented grains from different fermentation time. The results showed that 4 genera of fungi such as Issatchenkia, Talaromyces, Aspergillus and Eurotium are main dominant communities, they take 28.6%, 16.9%, 14.3% and 26.0% of all clones, respectively, and genus Issatchenkia and genus Talaromyces existed mainly in incipient period of fermentation, but some strains of genus Talaromyces also keep up to end of fermentation, genus Aspergillus become more after 4 week fermented, but genus Eurotium was more and more in the middle and end period of fermentation. The change trend and biological character of main dominant communities indicated that metabolizing of these fungi is related closely to the digestion of bio-molecule in fermented grains and formation of flavor in Chinese strong aromatic spirits.关键词：Chinese strong aromatic spirits;fermented grains;PCR;biological diversity;fungal community
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发布时间：2023-11-28 - 摘要：Abstract:Polyoxymethylene (POM) is an important plastic with pretty good properties. However, its poor impact strength and thermo-degradation limit its applications. In this paper, the polycaprolactone based thermoplastic polyurethane (TPU-1) with a Shore A hardness of 80 was selected to toughen POM，because this kind of TPU has the excellent mechanical properties and matchable viscosity with POM at the processing temperature around 190 ℃. The result shows that TPU-1 can effectively enhance the notched impact strength of POM and when the content of TPU increases to 40%, the notched impact strength of POM/TPU-1 blend abruptly increases and the co-continues phase structure forms. The elongation at break increases, while the tensile strength and modulus decrease with the increase of TPU-1 content. TPU-1 can extract some of the additives in POM, affect the crystallization process, and increase the thermo-degradation temperature of POM.关键词：polyoxymethylene;thermoplastic polyurethane;blend;toughening
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发布时间：2023-11-28 - 摘要：Abstract:There are a lot of burrs and branches after thinning the binary image of the light stripe, which will heavily affect the accuracy of the line-structure-light 3D shape measurement, so burrs and branches must be cut at first. A new pruning algorithm based on curve tracing was proposed, which can follow the backbone of the light stripe to find out the branches, and then eliminates branches and produce a high quality skeleton. The experimental results showed this algorithm can cut the branches and remove the false characters more rapidly and effectively, and lead to a good 3D reconstruction result.关键词：3D measurement;line structure light;branch;thinning;pruning algorithm
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发布时间：2023-11-28 - 摘要：Abstract:A precision ranger system for measuring the large machining pieces or structures is described. The system uses the principle of beat-wave measurement. The light source of this system is a frequency stabilized laser with a frequency stability of 1×10-7 (open air), which does not depend on any reference frequency. It operates in two longitudinal modes; i.e., the laser emits two beams, which generate in the common resonator of the laser. The beat frequency is about 790 MHz and the wavelength is about 380 mm. The two beams are naturally coaxial. The node of the beat-wave is used as sampling flag and the distance between the node and the close point is measured with double frequency interferometer, which is combined in the same optical system and its resolution is 0.08. As a precise ranger, it does not need a long guide or any heavy machinery. The system described here has the measuring range of 0~20 meters and the measuring uncertainty of 30 μm / 10 m.关键词：large dimension measurement;beat-wave interferometry;precision ranger;node
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发布时间：2023-11-28 - 摘要：Abstract:Grounding on the analysis of features of grid based and density based clustering methods, a hybrid clustering algorithm based on grid and density was presented. By clustering in two phases and using only a small number of seed objects in representative units to expand the cluster, the frequency of region query can be decreased, and consequently the cost of time is reduced. An equivalent rule was proposed to make smooth conversion between clustering parameters in that two phases. The algorithm keeps good feature of both density based and grid based clustering methods. It can discover clusters with arbitrary shape with high efficiency and is insensitive to noise. So it is applicable for data mining on large database. The application of the hybrid algorithm in data analysis of accelerometer demonstrates its effectiveness. It is of instructional meaning for the application of data mining in equipment monitoring and faults diagnosis.关键词：data mining;clustering;seed object
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发布时间：2023-11-28 - 摘要：Abstract:An accurate description of the behavior of workflow activities is the basis for controlling workflow processes. Approaches based on states to describing workflow activity behavior are widely adopted in current workflow management systems. However, informal semantic reprsentations of activity states are lack of accuracy and expandability, which leads to low adaptability of workflow management systems. Focus on the diversity and dynamic of business process management requirements, a formal semantic representation for workflow activity states was presented to support the fast reconfiguration of activity states. The relations between activity states and workitem states were firstly analyzed, and then based on which some basic concepts, such as activity state configuration set and universal activity state configuration set, were defined to describe the activity state semantic. By mapping an activity state onto a set of configurations with the same feature, the semantic of the activity state was formally defined. At last, a mechanism for fast reconfiguration of activity states was proposed and its effectiveness was verified by a practical example. The proposed approach can significantly improve the adaptability of workflow management systems in changing business environments.关键词：business process management;Workflow;activity state;semantic representation;reconfiguration
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发布时间：2023-11-28 - 摘要：Abstract:Based on the analysis of factors affecting credibility of large complex simulation systems, a credibility index system was given. Because credibility evaluation of large complex simulation systems involves lots of qualitative indices with multiple levels and granularities, hierarchical linguistic variables were used to acquire their evaluation information, and the two-tuple linguistic method was used to deal with the evaluation information with multiple sources and granularities,and the credibility quantification of large complex simulation systems was implemented. Practical applications proved that this quantification method is effective.关键词：large complex simulation systems;credibility quantification;credibility index system;hierarchical linguistic variables;two-tuple linguistic method
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发布时间：2023-11-28
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