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Green space is one of the main measures to alleviate urban heat islands (UHI). The transformation mechanism of daytime and nighttime scale sensitivity of vegetation coverage to reduce the UHI effect in a daily cycle has been unclear. As a result, we propose a scale sensitivity measurement algorithm to study the spatial and temporal response relationship between UHI and green coverage. Based on the scale theory of landscape ecology and the method of geostatistical analysis, we adopted ArcGIS, MATLAB, SPSS, and other data processing software as well as a large amount of measured and high-resolution satellite imagery data of Beijing and Tianjin to quantitatively study their spatial scale sensitivity and daily variation features of urban green spaces to reduce summer UHI. The results show that first, the green coverage rate and the UHI intensity experience positive and negative correlations during the daytime, and negative correlations at night. When the correlation coefficient is significant, there is a linear relationship between the UHI intensity and the core green rate. Second, the reduction of the UHI by green spaces displays spatial and temporal change scale sensitivity characteristics. The radius scale of daytime sensitivity is 15m, and the radius scale of nighttime sensitivity is 60m. The study's conclusion enriches the theoretical parameters of landscape ecological scales and patterns, and provides spatial and temporal scales for systematic planning of green space to reduce UHI.

The purpose of this paper is to study the pressure fluctuation characteristics in the sidewall gaps of a centrifugal dredging pump in detail and discover the excitation sources.

An unsteady numerical simulation with shear–stress transport–scale-adaptive simulation (SAS-SST) model was conducted for a centrifugal pump considering the sidewall gaps. The numerical codes were validated by a model test carried out in China Water Resources Beifang Investigation, Design and Research Co., Ltd. Fast Fourier transform was used to obtain the frequency components of the pressure fluctuation.

Pressure fluctuation characteristics inside the pump were analyzed for a condition near the design point. In the sidewall gaps, the circumferential, radial and axial distribution of the pressure fluctuation amplitude follow different laws. The non-axisymmetrical distribution of pressure fluctuation in the sidewall gaps shows that the unsteady flow in the volute casing which has a non-axisymmetrical geometry imposes an evident effect on the flow field in the sidewall gaps and the interaction between the main flow and the clearance flow cannot be neglected. There are several frequency components appearing as the dominant frequencies at different locations in the sidewall gaps, but the relatively stronger pressure fluctuations are all dominated by the rotating frequency. It indicates that the rotating impeller, which originally makes the shrouds rotate, is the primarily excitation source of the pressure fluctuations in the sidewall gaps.

The pressure fluctuation characteristics in the sidewall gaps of centrifugal pumps were first comprehensively analyzed. Unsteady flows in the sidewall gaps should be considered during the design and operation of centrifugal pumps.

The purpose of this study is to corroborate the advanced tribological properties of graphene as a lubricant additive.

Different concentrations of functionalized graphene were coated on the substrate surface. Tribological properties of the graphene lubricants were carried out by ball-on-disk tribology tests. Wear mechanism of functionalized graphene was studied by observing wear scars on the substrate surface. Finally, the wear resistance of modified graphene was calculated by calculating and analyzing the applied experimental conditions and the obtained experimental data.

The best concentration of graphene lubricant is 0.5 wt.% which shows the best tribological performance. And the coefficient of friction is 0.08. Compared with the dry friction condition, the coefficient of friction and wear rate of best graphene lubricant decreased by 80% and 82%.

The formula of graphene lubricant is independently developed and works very well. Graphene lubricant can prevent the substrate from oxidation. The thickness of the graphene lubricant is about 4-7µm. The concept of anti-wear strength was introduced in this paper. When 0.5 Vol.% graphene was added, the anti-wear strength was greatly improved from 115.3 kg·mm-2 to 657.6 kg·mm-2.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2019-0344

The purpose of this paper is to increase wear resistance of aluminum.

The authors have studied the ways to improve the tribological performance of aluminum by assembling stearic acid on aluminum coated by sol-gel-derived TiO₂ film. The samples were characterized by infrared spectroscopy, contact angle measurements and a macro friction and wear tester.

Enhanced wear resistance was clearly obtained after functionalization of TiO₂ film on aluminum by stearic acid.

The relevant results might be helpful for guiding the surface modification of aluminum devices in industrial applications.

The purpose of this paper is to seek an efficient method to tackle the energy provision problem for smart grid with sparse constraints and distributed energy and storage devices.

A complex smart grid is first studied, in which sparse constraints and the complex make-up of different energy consumption due to the integration of distributed energy and storage devices and the emergence of multisellers are discussed. Then, a real-time pricing scheme is formulated to tackle the demand response based on sparse bilevel programming. And then, a bilevel genetic algorithm (BGA) is further designed. Finally, simulations are conducted to evaluate the performance of the proposed approach.

The considered situation is widespread in practice, and meanwhile, the other cases including traditional model without the sparse constraints can be seen as its extensions. The BGA based on sparse bilevel programming has advantages of “no need of convexity of the model.” Moreover, it is feasible without the need to disclose the private information to others; therefore, privacies are protected and system scalability is kept. Simulation results validate the proposed approach has good performance in maximizing social welfare and balancing system energy distribution.

In this paper, the authors consider the sparse constraints due to the fact that each user can only choose limited utility companies per time slot. In reality, there exist some other sparse cases, which deserve further study in the future.

To the best of the authors’ knowledge, this is one of the very first studies to address pricing problems for the smart grid with consideration of sparse constraints and integration of distributed energy and storage devices.

The purpose of this study is to describe and observe the influence of boundary slip associated with an arbitrary entrainment angle on the contact lubrication properties of ellipses.

Based on the modified Reynolds equation, the boundary slip of any angle is considered in the elliptic contact, and numerical simulation is carried out. In the above calculation, the progressive mesh densification method is used, which greatly reduces the computation time.

The results indicate that the variation of film thickness corresponding to different entrainment angles is distinct from those without considering boundary slip. In addition, boundary slip reduces the central film thickness and minimum film thickness, which makes the hydrodynamic pressure distribution smoother.

The present study focuses on the specific condition with the arbitrary direction of rolling and sliding velocity found in hypoid gears and worm, and some other components. The influence of boundary slip associated with arbitrary entrainment angle on the lubrication film thickness in elliptical contacts is first revealed, which improves a good understanding of elastohydrodynamic lubrication characteristics.

This study aims to demonstrate how integration is achieved in an explanatory sequential mixed-methods design by assessing the effect of collaborative cultural dimensions on supply chain collaboration amongst firms in Ghana's downstream petroleum sector. Specifically, the study examined how collectivism, long-term orientation, power symmetry, as well as uncertainty avoidance influence supply chain collaboration. Besides, it also demonstrates how integration is achieved in an explanatory sequential mixed-methods design.

Using an explanatory sequential mixed-methods design, the study employed a partial least squares structural equation modelling (PLS-SEM) analysis of quantitative data (N = 166), followed by a thematic analysis of eight semi-structured interviews to explain how and why the dimensions of collaborative culture impact supply chain collaboration.

The quantitative findings suggest that three out of the four dimensions of culture significantly predict supply chain collaboration. Integrating the quantitative and qualitative findings suggests convergence between the results of the quantitative and qualitative phases of the study as the qualitative results compliment the quantitative findings and offer more nuanced understanding of the cultural mechanisms responsible for successful supply chain collaborations.

The findings provide managers in the downstream petroleum sector with insights into how and why the dimensions of collaborative culture influence supply chain collaboration. These managers should, therefore, build corporate cultures characterized with high levels of long-term orientation, power symmetry and uncertainty avoidance.

Owing to the role of culture in successful supply chain collaborations, this study, through a mixed-methods design, links the dimensions of collaborative culture with supply chain collaboration in the downstream petroleum sector. Moreover, it demonstrates how integration and complementarity are achieved at the study design, methods, as well as the interpretation and reporting levels of an explanatory sequential mixed-methods design.

Given the increasingly important role of knowledge capital on key outcomes and innovation capabilities of organizations, this paper aims to investigate the influences of knowledge-based human resource management (KHRM) practices on innovation capability of firms via mediating role of knowledge sharing (KS). This study also examines whether competitive intensity moderates the effects of KS behaviors on specific aspects of innovation capability, namely, product and process innovation.

This paper used structural equation modeling to examine the level of how KHRM practices and KS impact on two types of innovation capability, namely, product innovation and process innovation using data collected from 265 participants in 112 manufacturing and service firms in Vietnam.

The research findings confirm the mediating roles of KS behaviors between KHRM practices and two specific types of innovation. Besides, the paper first reveals the moderating role of competitive intensity in the relationships between KS and product innovation. The results underline the necessity of building a climate of KHRM practices to stimulate employees sharing knowledge, which, in turn, positively promotes innovation capabilities in an organization.

Future research should investigate the impact of different forms of human resource management (HRM) practices on innovation via the mediating effects of certain aspects of KS to bring better understanding on the importance of HRM practices and knowledge resources in pursuing innovation competence.

This paper offers leaders a deeper understanding of potential effects of competitive intensity and environmental factors to promote innovation capabilities in their firms.

This paper has significant contributed to theoretical and practical initiatives on theory of HRM practices and knowledge management by showing different moderating and mediating mechanism thereby firms can follow to enhance innovation capability of firms in developing and emerging markets.

The purpose of this study is to investigate the effect of transformational leadership (TL) of school leaders on tacit and explicit knowledge sharing (KS) of teachers via the mediating roles of knowledge self-efficacy. This study also attempts to bring a deeper insight on the correlation between TL and KS by exploring the moderating effect of knowledge-oriented school culture (KSC).

The paper used the quantitative approach and structural equation modeling to test the relationship among the latent factors in the proposed research model using data collected from 335 teachers in Vietnamese universities.

The findings revealed that TL might be an important precursor to create significant influences on tacit and explicit KS behaviors of teachers directly or indirectly through its positive effect on knowledge self-efficacy. In addition, the paper highlights the moderating role of KSC in strengthening the impact of TL on tacit and explicit KS behaviors of teachers.

This paper offers principals and managers in higher education a novel approach and valuable understanding of the effective pathways to foster KS behaviors of teachers.

This study is unique in its attempts to bridge research gaps in the literature and advance the insights of how school leadership fosters knowledge self-efficacy and KS willingness of teachers through practicing TL style and building a knowledge-oriented climate in higher education.

This paper aims to investigate the influence of collaborative culture and knowledge sharing on innovation performance via moderating role absorptive capacity.

This paper used structural equation modeling to examine the level of how collaborative culture and knowledge sharing impact on innovation performance using data collected from 271 Vietnamese firms.

The research findings show knowledge sharing mediates the relationship between collaborative culture and innovation performance. It highlights the moderating role of absorptive capacity in fostering the effects of tacit and explicit knowledge sharing on innovation performance.

Further research should examine the potential moderating effects of absorptive capacity in the knowledge management–innovation relationship to bring deeper understanding on the role of knowledge resource and innovation.

This paper offers leaders a deeper understanding of the necessary factors and conditions to promote innovation performance in their firms.

This paper significantly contributes to theoretical and practical initiatives of innovation by highlighting the antecedent roles of collaborative culture, the mediating role of knowledge sharing and moderating role of absorptive capacity.