Search results

The purpose of this paper is to investigate the tribological performance of Cr₃C₂–NiCr–Mo–BaF₂ composite sliding against a Si₃N₄ ball at high temperatures.

A Cr₃C₂–NiCr composite and a Cr₃C₂–NiCr–Mo–BaF₂ composite were prepared using spark plasma sintering. Tribological properties of the composites were investigated using a ball-on-disk type tribotester. The relationships among the microstructure, wear mechanism and tribological performance were determined by analyzing the wear track morphologies and the glaze layer’s phase composition.

The wear rate of the Cr₃C₂–NiCr–Mo–BaF₂ composite was approximately one order of magnitude lower than that of the Cr₃C₂–NiCr composite from 700°C to 900°C when sliding against a Si₃N₄ ball. The favorable tribological performance of the Cr₃C₂–NiCr–Mo–BaF₂ composite at high temperatures results from the synergistic lubrication of MoOx, BaF₂ and BaMoO₄.

This paper reports a new Cr₃C₂–NiCr matrix self-lubricating composite with better tribological properties than Cr₃C₂–NiCr composite at temperatures up to 900°C through Mo and BaF₂ addition.

Five-level rectifiers have received widespread attention because of their excellent performance in high-voltage and high-power applications. Taking a five-level rectifier with only four-IGBT for this study, a sliding mode predictive control (SMPC) algorithm is proposed to solve the problem of poor dynamic performance and poor anti-disturbance ability under the traditional model predictive control with the PI outer loop.

First, mathematical models under the two-phase stationary coordinate system and two-phase synchronous rotating coordinate system are established. Then, the design of the outer-loop sliding mode controller is completed by establishing the sliding mode surface and design approach rate. The design of the inner-loop model predictive controller was completed by discretizing the mathematical model equations. The modulation part uses a space vector modulation technique to generate the PWM wave.

The sliding mode predictive control strategy is compared with the control strategy with a PI outer loop and a model predictive inner loop. The proposed control strategy has a faster dynamic response and stronger anti-interference ability.

For the five-level rectifier, the advantages of fast dynamic influence and parameter insensitivity of sliding mode control are used in the voltage outer loop to replace the traditional PI control, and which is integrated with the model predictive control used in the current inner loop to form a novel control strategy with a faster dynamic response and stronger immunity to disturbances. This novel strategy is called sliding mode predictive control (SMC).

Prior literature has long argued that knowledge networks contain great opportunities for innovation, and researchers can identify these opportunities using the properties of knowledge networks (PKNs). However, previous studies have examined only the relationship between structural PKNs (s-PKNs) and innovation, ignoring the effect of qualitative PKNs (q-PKNs), which refer to the quality of the relationship between two elements. This study aims to further investigate the effects of q-PKNs on innovation.

Using a panel data set of 2,255 patents from the Chinese wind energy industry, the authors construct knowledge networks to identify more PKNs and examine these hypotheses.

The results show that q-PKNs significantly influence recombinant innovation (RI), reflecting the importance of q-PKNs analysed in this study. Moreover, the results suggest that the combinational potential of an element with others may be huge at different levels of q-PKNs.

This study advances the understanding of PKNs and RI by exploring how q-PKNs impact RI. At different levels of PKNs, the potential of the elements to combine with others and form innovation are different. Researchers can more accurately identify the opportunities for RI using two kinds of PKNs. The findings also provide important implications on how government should provide support for R&D firms.

Cross-channel integration improves the operations of multi-channel and omnichannel marketing and increase firms' overall performance. By addressing the extant gaps in current literature, this configurational analysis aims to test the combined effects of organizational, channel and environmental factors on cross-channel integration.

Data were collected from a sample of 180 manufacturers. Necessary condition analysis (NCA) was used to test whether two organizational factors (firm size and IT capability), one environmental factor (environmental dynamism) and two channel factors (channel diversity and proportion of direct channels) were necessary or unnecessary conditions for high cross-channel integration. Fuzzy-set qualitative comparative analysis (fsQCA) was applied to analyze the configurational factors of high vs low cross-channel integration.

First, firm size and IT capability are non-linear and substitute for each other in affecting cross-channel integration in a diversified channel system with a high proportion of direct channels. Second, in a dynamic environment, firms with large size and IT advantage could achieve high cross-channel integration by diversifying channel types or increasing the proportion of direct channels. Third, the effect of channel diversity and proportion of direct channels on cross-channel integration is asymmetric depending on other antecedent conditions.

The authors tested a configurational framework developed from multiple theoretical perspectives. The authors' empirical findings contribute to the literature by providing insights into the mechanisms underlying the formation of high and low cross-channel integration. The results suggest multiple ways for firms to promote cross-channel integration by adjusting channel factors based on configurational conditions.

Cotton is one of the most common nature textile fiber that is widely used in clothing, bedding and decorative fields due to its comfort. However, the cellulosic cotton fiber has its own drawbacks. Cotton fiber belongs to flammable material with the limiting oxygen index (LOI) value about 18% that restricts its applications. Cotton fiber is easy to crease during the repeat wearing and laundering process that will influence the wearability. Therefore, it is very important to improve the flame retardancy and anticrease performance of cotton fabric.

In this study, flame retardant and anticrease multifunctional modifications of cotton fabric were conducted by one-step pad–dry–cure process using eco-friendly phytic acid and 1, 2, 3, 4-butanetetracarboxylic acid.

The results of limited oxygen index (LOI) values and vertical burning test indicate that the flame retardancy of modified cotton fabric was greatly improved. The LOI value of modified cotton fabric reached 30.8% when the usage of phytic acid was 12%. The crease recovery angle was over 250° of the modified cotton fabric revealing good anticrease performance.

This research provides a novel feasible cost-effective one-step method for the multifunctional modified cellulosic fiber using eco-friendly chemical agents.

For the laser powder bed fusion (L-PBF) technology, the side surface quality is essentially important for industrial applicated parts, such as the inner flow parts. Contour is generally adopted at the parts’ outline to enhance the side surface quality. However, the side surface roughness (Ra) is still larger than 10 microns even with contour in previous studies. The purpose of this paper is to study the influence of contour process parameters, laser power and scanning velocity on the side surface quality of the AlSi10Mg sample.

Using L-PBF technology to manufacture AlSi10Mg samples under different contour process parameters, use a laser confocal microscope to capture the surface information of the samples, and obtain the surface roughness Ra and the maximum surface height Rz of each sample after analysis and processing.

The results show that the side surface roughness decreases with the increase of the laser power at the fixed scanning velocity of 1,000 mm/s, the side surface roughness Ra stays within the error range as the contour velocity increases. It is found that the Ra increases with the scanning velocity increasing and the greater the laser power with the greater Ra increases when the laser power of contour process parameters is 300 W, 350 W and 400 W. The Rz maintain growth with the contour scanning velocity increasing at constant laser power. The continuous uniform contour covers the pores in the molten pool of the sample edge and thus increase the density of the sample. Two mechanisms named “Active adhesion” and “Passive adhesion” cause sticky powder.

Formation of a uniform and even contour track is key to obtain the good side surface quality. The side surface quality is determined by the uniformity and stability of the contour track when the layer thickness is fixed. These research results can provide helpful guidance to improve the surface quality of L-PBF manufactured parts.

In recent years, private brands for e-commerce platforms have experienced rapid growth. However, whether these platforms developing private brands should share their demand information with others and how such information sharing affects the sales format selection of national brand manufacturers have puzzled firm managers in practice. This paper aims to investigate the information-sharing strategy for the e-commerce platform and its influence on the sales format selection in the presence of the private brand.

The authors use a game-theoretical model to examine the interaction between the information-sharing strategy and sales format selection in a supply chain consisting of a manufacturer and a platform that operates a private brand.

The equilibrium results show that when the commission rate is low, the manufacturer favors agency selling, and the platform shares demand information with the manufacturer; when the commission rate is high, the manufacturer prefers reselling, and the platform does not share the information. This preference is affected by information forecasting accuracy; as the information forecasting accuracy increases, the manufacturer prefers to adopt agency selling, and the platform tends to share the information. Interestingly, under agency selling, sharing information with the manufacturer can increase the platform’s profit from selling the private brand and achieve a win-win situation for them. Furthermore, we show that the manufacturer can inspire the platform to share the information with himself by adopting agency selling, whereas the platform sharing the information improves the probability that the manufacturer adopts agency selling. Moreover, the manufacturer may have a first-mover advantage. In particular, the manufacturer moving first increases the likelihood that the manufacturer chooses agency selling and the platform shares the information.

This paper contributes to sales format literature by exploring the effect of information sharing strategy on sales format selection in the presence of the private brand and can help manufacturers and platforms to make suitable decisions regarding information sharing and sales format selection.

The purpose of this paper is to examine the increase in the cigarette excise tax needed to keep tax revenue constant in the face of the cancellation of the tobacco leaf tax.

Equilibrium‐displacement model was employed to simulate the substitution effect.

The results suggest the “substitution effect elasticity (SEE)” is between −0.127 and −0.063. This means a 100 per cent cut in the tobacco leaf tax rate would necessitate an increase in the cigarette excise tax rate of between 6.3 and 12.7 per cent. Sensitivity analysis indicates SEE is most sensitive to the retail demand elasticity and oligopoly power and least sensitive to input substitution elasticity and returns to scale.

This paper provides a framework to analyze the policy effects of the Chinese tobacco industry. The findings in this study are very important for government to make policies in the future.

The purpose of this paper is to develop new types of anchor bolt materials by adding corrosion-resistant elements for alloying and microstructure regulation.

Three new anchor bolt materials were designed around the 1Ni system. The stress corrosion cracking resistance of the new materials was characterized by microstructure observation, electrochemical testing and slow strain rate tensile testing.

The strength of the new anchor bolt materials has been improved, and the stress corrosion sensitivity has been reduced. The addition of Nb makes the material exhibit excellent stress corrosion resistance under –1,200 mV conditions, but the expected results were not achieved when Nb and Sb were coupled.

The new anchor bolt materials designed around 1Ni have excellent stress corrosion resistance, which is the development direction of future materials. Nb allows the material to retain its ability to extend in hydrogen-evolution environments.

Wear failure happens frequently in rubber seal of high-speed rotating shaft because of the dry friction. Some traditional lubrication methods are not effective because of the restrictions on the relative high speed, temperature and others. This paper aims to present a new method of lubrication with gas film for the rotation shaft seal based on the contact design.

To obtain the generation condition of gas film and good effect of lubrication in the contact gap between the shaft and its seal, a series of micro-spiral grooves are designed on the contact surface of rubber seal so as to obtain a continuous dynamic pressure difference.

The result is that the distribution of the gas film in the micro-gap is continuous under the design of the spiral grooves and the contact with eccentricity because of the deformation of rubber seal, which is verified through the simulation calculation and experiment test. It is confirmed that the lubrication method with gas film through designing micro-spiral grooves on the contact surface is effective, and can achieve self-adaptive air lubrication for the high-speed shaft under the premise of the reliable sealing.

The method of gas film lubrication is realized through designing a microstructure of spiral grooves on the rubber surface to change the contact status, which can form a mechanism of adaptive lubrication to reduce the dry friction automatically in the contact gap. For the cross-scale difference between the rubber seal and gas film, a new modeling method is presented by building the mapping relation for the split blocks and repairing technique with integrated computer engineering and manufacturing, to reduce the possibility of nonconvergence and improve the efficiency and accuracy of calculation.