This paper provides an evaluation framework to explore the linking mechanisms between customer knowledge management competence (CKMC) and Balanced Scorecard (BSC). With a case study from ...Chengdu-Chongqing Economic Circle of China, this paper attempts to empirically justify the framework. An index system was established for evaluating CKMC based on BSC and knowledge management process, the weight design and consistency check of the indexes were implemented by using the analytic hierarchy process (AHP), and the overall evaluation value and concrete index scores at all levels were obtained via the fuzzy evaluation method. Empirical results show that CKMC performance measurement indicators were ranked in order of importance as Business process performance dimensions (0.465), System support dimensions (0.289), Customer communication dimensions (0.152) and Market performance dimension (0.094). It also shows that the overall score of CKMC was 3.404, reflecting that the CKMC was in a state of general satisfaction. This research also identifies key factors hindering implementation of CKMC, including Attention from senior leaders (2.871), customer knowledge sharing efficiency (2.928), and information technology level (3.133). This research could contribute to CKM theory by extending customer knowledge management competence research with BSC initiatively. For practitioners, this study may provide useful suggestions to identify key factors promoting business CKMC, and finally promotes sustainable development of Agritourism.
•A “C” shape TTT diagram of a real coal slag was constructed.•Compositions can change after a long time heat treatment with the elements Si, Na, K, S lost.•The crystallized spinel distributed in the ...slag with irregular shape and formed a network resulting in the sharp increase of the viscosity.
In entrained flow gasifiers, crystallization inside the liquid slag can cause an increase of the slag viscosity, affecting flow along the wall and resulting in operational challenges. In the study reported here, a real Chinese ash was investigated for its crystallization behavior as well as the viscosity. Differential Scanning Calorimetry (DSC) and the Single Hot Thermocouple Technique (SHTT) were combined to measure the crystallization temperature and observe the crystallization process, constructing the temperature-time transformation (TTT) diagram. The ash was heated and then quenched to determine the crystalline phases. Unlike the synthetic slag mixed with oxides, the compositions of real ash had some variations after the long time heat treatment, which may attribute to the reducing minerals in the ash. Under inert atmosphere, gehlenite and spinel were the main crystals in cooling process. While under reduced atmosphere, the amount of crystals decreased especially gehlenite. Spinel was widely distributed inside the slag with irregular shape forming a network which caused the sharp increase of viscosity. The temperature of critical viscosity (Tcv) was around 1310°C corresponding to the spinel proportion calculated about 20%.
To solve the problem of insufficient predictability in the classical models for the Ti6242s alloy, a new constitutive model was proposed, based on the partial derivatives from experimental data and ...the Taylor series. Firstly, hot compression experiments on the Ti6242s alloy at different temperatures and different strain rates were carried out, and the Arrhenius model and Hensel-Spittel model were constructed. Secondly, the partial derivatives of logarithmic stress with respect to temperature and logarithmic strain rate at low, medium and high strain levels were analyzed. Thirdly, two new constitutive models with first- and second-order approximation were proposed to meet the requirements of high precision. In this new model, by analyzing the high-order differential data of experimental data and combining the Taylor series theory, the minimum number of terms that can accurately approximate the experimental rheological data was found, thereby achieving an accurate prediction of flow stress with minimal material parameters. In the new model, by analyzing the high-order differential of the experimental data and combining the theory of the Taylor series, the minimum number of terms that can accurately approximate the experimental rheological data was found, thereby achieving an accurate prediction of flow stress with minimal material parameters. Finally, the prediction accuracies for the classical model and the new model were compared, and the predictabilities for the classical models and the new model were proved by mathematical means. The results show that the prediction accuracies of the Arrhenius model and the Hensel-Spittel model are low in the single-phase region and high in the two-phase region. In addition, second-order approximation is required between the logarithmic stress and logarithmic strain rate, and first-order approximation is required between logarithmic stress and temperature to establish a high-precision model. The order of prediction accuracy of the four models from high to low is the quadratic model, Arrhenius model, linear model and HS model. The prediction accuracy of the quadratic model in all temperatures and strain rates had no significant difference, and was higher than the other models. The quadratic model can greatly improve prediction accuracy without significantly increasing the material parameters.
Wire arc additively manufactured (WAAM) Ni-based materials have good properties but are costly and hard to cut, leading to difficulties in machining after welding and wasting the materials. To ...overcome these shortcomings, this work proposes a method of surfacing Fe-based alloy layers on WAAM Ni-based material. The effect of this method on the microstructure and wear properties of WAAM Ni-based materials is discussed. In this work, a Fe-based alloy (JX103) was welded as the last layers of the WAAM Ni-based superalloy (JX201) material. The hardness, microstructure, and wear behavior of the material with different residual Fe-based materials were tested and analyzed. Our results indicate that the surface hardness was smoothly increased from HV350 to HV400 by overlaying Fe-based alloy layers. Microstructure analysis shows that γ-Fe gradually disappears, and the carbide form changes from WAAM Ni-based superalloys to Fe-based alloys. In the fusion boundary, the occurrence of cellular dendritic growth, a type -Ⅱ boundary, and low dilution indicate good crack resistance and good connection performance between these two materials. The wear test showed that the wear resistance of JX201 was decreased by changing the last layer to JX103. However, as the residual thickness of JX103 decreased, the influence gradually reduced. Meanwhile, the wear mechanism changed from severe abrasive and adhesive wear to light abrasive wear. When the thickness is less than 0.5 mm, the wear weight per minute is at the same level as the sample without JX103.
The aim of this research is to investigate China’s urban green total factor productivity (TFP) under the background of progressing urbanization and intensifying environmental pollution, and found out ...its main influencing factors. In this paper, green TFP of 285 prefecture-level cities in China from 2005 to 2012 was estimated through Malmquist productivity index. Results showed that the annual growth of green TFP in main cities in China is 3.5% and the overall growth declines gradually. Viewed from decomposition of green TFP, technical progress is the main contributor of green TFP growth. Furthermore, the northern coastal region has achieved the highest annual growth of green TFP (4.5%) and the northwest region achieved the lowest growth of green TFP (1.24%), indicating the great regional differences of green TFP and economic growth quality in China. According to analysis on influencing factors of green TFP in main cities, it has been concluded that per-capita urban road area, number of Internet users, proportion of fiscal expenditures, environmental regulation level and technical input are significantly positively correlated with green TFP, while industrial structure and foreign direct investment (FDI) are significantly negatively correlated. Finally, policy suggestions to improve urban green TFP in China were proposed.
•A rNEMD simulation and its experimental validation for thermal conductivity of were conducted for molten slag.•The existence of NBOs enhances the anharmonicity and shortens the interatomic distance ...to reduce phonon mean free path.•An equivalent molar concentration of the Q4 tetrahedron (XQ4) is defined.•The approximate positive linear relationships between the thermal conductivities and XQ4 are obtained.
The built up of the slag layer is a character of the entrained-flow gasifier, and its thickness distribution and heat transfer characteristics affect the stable operation of gasification, which is closely related to the thermal conductivity of molten slag. A non-stationary hot wire experimental method and a reverse non-equilibrium molecular dynamics simulation method were combined to investigate the thermal conductivity of the SiO2-Al2O3CaO-Fe2O3−MgO molten slag with a mass ratio of CaO ranging from 5 to 25 wt.%. The slag microstructure information of the distribution of oxygen and tetrahedron Qn was calculated by molecular dynamics simulation. A good agreement within the deviation of 18% between the measured and calculated thermal conductivity over the entire operating temperature range is observed, and one can find that thermal conductivity decreases significantly as the CaO content increased. The principal pathway for CaO modifying the network structure is the connection between two tetrahedral structures by generation of the Si-O-Ca and Al-O-Ca through the fracture of Si-O-Si and Si-O-Al. The rise of CaO promotes the formation of non-bridging oxygen (NBO) and the decomposition of bridging oxygen. The existence of NBOs leads to an enhancement of anharmonicity and shortens the interatomic distance in the tetrahedral structure, which aggravates phonon scattering to reduce phonon mean free path, thereby decreasing the thermal conductivity. Since the phonon propagation is restricted to short-range tetrahedron separated by structural disorder, the Q4 structure is the most sensitive to the addition of CaO. An equivalent molar concentration of the Q4 tetrahedron (XQ4) is defined and the approximate positive linear relationships between the thermal conductivities and XQ4 are obtained.
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The thermal conduction behavior of slags affects the stable operation of entrained-flow gasifier. The thermal conduction behavior of five-element synthetic slag system with four series variable ...composition was systematically studied. The turning point of thermal conductivity changing with temperature is observed in each sample, where thermal conductivity is at peak value. The temperature of this point is defined as the transition temperature Tct, which is determined by the intersection point of two fitting lines based on two mechanisms. When T > Tct, the thermal conductivity is exponentially related to the reciprocal of temperature. With decrease of temperature, two different downward trends of thermal conductivity are observed, which is probably caused by the difference of crystal precipitating rate, and the effects of glassy and crystal state also cannot be neglected. When T < Tct, the thermal conductivity is positively linear with temperature. It was found that Tct is between the initial crystallization temperature and the ash melting point, where thermal conductivity of slag begins to be affected by the crystal thermal conduction. A prediction model of the transition temperature is established based on the liquid phase temperature without the requirement of experimental tests and verified by five actual coal ashes.
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•Thermal conduction behavior of slags is systematically studied and equations for calculation is fitted.•Two trends of thermal conductivity changing with temperature is explained.•Determination and physical meaning of transition temperature in thermal conductivity of slags is proposed.•A prediction model of the transition temperature is established and verified.
To realize automatic wire arc additive manufacturing (WAAM) of a large aviation die with a complex gradient structure, a new contour-parallel path generation strategy was proposed and practically ...applied. First, the planar curve was defined as a vertical slice of a higher-dimensional surface and a partial differential equation describing boundary evolution was derived to calculate the surface. The improved Finite Element Method (FEM) and Finite Difference Method (FDM) were used to solve this partial differential equation. Second, a cross section of a large aviation die was used to test the path-generation algorithms. The results show that FEM has a faster solving speed than FDM under the same solving accuracy because the solving domain of FEM mesh was greatly reduced and the boundary mesh could be refined. Third, the die was divided into three layers: base layer, transition layer (Fe-based material) and strengthening layer (Co-based material) according to the difference of the temperature and stress field, and corresponding WAAM process parameters has been discussed. The optimum welding parameters are obtained as follows: voltage is 28 V, wire feeding speed is 8000 mm/min and welding speed is 450 mm/min. Finally, the path generation strategy was practically applied to the remanufacture of the large aircraft landing gear die with a three-layer structure. The application test on aircraft landing gear dies justified the effectiveness of the algorithms and strategy proposed in this paper, which significantly improved the efficiency of the WAAM process and the service life of large aviation dies with complex gradient structures. The microstructure of the fusion zone shows that the base metal and welding material can be fully integrated into the welding process.
•An in-situ observation was performed to record the crystallization process of a synthetic coal slag.•Temperature Time Transformation (TTT) and Continuous Cooling Transformation (CCT) diagrams of the ...slag were constructed.•With decreasing temperature or increasing cooling rates, the crystals became finer and smaller.•Based on the classic JMA equation, the crystallization kinetics and mechanism were determined.
In slagging gasifiers, the crystallization ratio and crystal morphology are of great importance to fluidity of slag. Although increasing attention has been paid to the influence of crystallization on viscosity, few studies have investigated crystallization kinetics in slag melts due to challenges associated with high temperature and experimental complexity. In order to gain an understanding of crystallization characteristics, an in-situ observation Single Hot Thermocouple Technique (SHTT) system was set up and direct observation of the crystallization process was conducted. After completely melting, the slag would form a film as a result of its surface tension on the tip of the thermocouple. When the slag reached a certain degree of undercooling, crystals would precipitate from the homogenous melt. The crystallization ratio was quantitatively determined by taking advantage of the crystal color difference from the surroundings. A synthetic slag was produced from five oxides, with composition 38.4SiO2–14.8Al2O3–20.8CaO–19.1Fe2O3–6.9MgO, which is modeled on a real Chinese coal ash slag with low liquidus temperature and distinct crystallization characteristics. The crystallization characteristics of this synthetic slag were studied under isothermal temperatures and continuous cooling rates. Temperature Time Transformation (TTT) and Continuous Cooling Transformation (CCT) diagrams of the slag were constructed and a fundamental understanding of crystallization influenced by temperature and cooling rates was obtained. With decreasing temperature or increasing cooling rates, the crystals became finer and smaller. At lower temperatures with high degrees of undercooling the incubation time was shortened and the crystallization ratio increased. The influence of cooling rate was not significant until it exceeded 80°C/min. Then the growth of crystals was greatly suppressed by high cooling rates, even appearing glassy when it surpassed the critical cooling rate. Based on the classic JMA equation, the crystallization kinetics and mechanism were determined. The Avrami parameter n indicates that at temperatures higher than 1200°C, interfacial reaction mainly controlled the crystallization process, while at lower temperatures, diffusion was dominant. The crystals formed in different temperature regions may be different phases, which can also be predicted by Factsage Software, but needs further validation.
To improve the service life and reduce the repair cost of continuous casting rollers, a new welding-hammering hybrid remanufacturing process in which the roller was designed with a gradient structure ...was proposed, and corresponding equipment was developed. First, the failure modes and their causes for a continuous casting roller were analyzed by numerical simulation. The cyclic tension-compression shear stress, cyclic tension-compression normal stress, thermal cycle, and highly corrosive environment caused fatigue cracking and overall peeling of the roller surface. Second, the gradient structure composed of a base layer, transition layer, and strengthened layer of a continuous casting roller was designed, and materials for each layer were selected according to their different service conditions. Third, novel equipment for continuous welding-hammering composite remanufacturing was developed, and the optimized process parameters were obtained through welding experiments. Finally, an application test was carried out; the microscopic analysis showed that refined grains, fewer welding defects, and better surface toughness were obtained. Compared with traditional remanufacturing processes without hammering, the welding-hammering hybrid process achieved a forged structure instead of as-cast structure, which significantly improved the service life of the continuous casting roller by about 100%.
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