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This study aims to study the mechanical, photoelectric, and thermal reliability of SAC307 solder joints with Ni-decorated MWCNTs for flip-chip light-emitting diode (LED) package component during aging. By adding nanoparticles (Ni-multi-walled carbon nanotubes [MWCNTs]) to the solder paste, the shear strength and fatigue resistance of the brazed joint can be improved. However, the aging properties of Ni-modified MWCNTs composite solder joints have not been deeply studied. In this research, the mechanical, photoelectric and thermal reliability of SAC307 packaged flip-chip LEDs with Ni-MWCNTs added during aging were studied.

Compared with SAC solder alloys, the effects of different contents (0, 0.05, 0.1 and 0.2 Wt.%) of Ni-MWCNTs on the photoelectric and thermal properties of composite solder joints were examined. To study the aging characteristics of composite solder joints, the solder joints were aged at 85°C/85% relative humidity.

The addition of an appropriate amount of reinforcing agent Ni-MWCNTs reduces the density of the composite solder to 96% of the theoretical value of the SAC solder alloy. In addition, the microhardness increases and the wetting angle decreases. Two different phase compositions were observed in the solder joints with Ni-MWCNTs reinforcement: Cu₃Sn and (Cu, Ni)₆Sn₅. The solder joints of SAC307-0.1Ni-MWCNTs exhibit the highest luminous flux and luminous efficiency of flip-chip LED filaments, the lowest steady-state voltage and junction temperature. And with the extension of the aging time, its aging stability is the best. In short, when the addition amount of Ni-MWCNTs is 0.1 Wt.%, the solder joints exhibit the best wettability and the thinnest intermetallic compound layer. And the shear strength of the tested solder joints is the best, and the void ratio is the lowest. At this time, the enhancement effect of Ni-MWCNTs on the composite solder has been best demonstrated.

The content range of enhancer Ni-MWCNTs needs to be further reduced.

The authors have improved the performance of Ni-modified MWCNTs composite solder joints.

Composite solder with high performance has great practical application significance for improving the reliability and life of the whole device.

The purpose of this paper is to investigate the effect of different soldering temperatures on the performance of chip-on-board (COB) light sources during vacuum reflow soldering.

First, the influence of the void ratio of the COB light source on the steady-state voltage, luminous flux, luminous efficiency and junction temperature has been explored at soldering temperatures of 250°C, 260°C, 270°C, 280°C and 290°C. The COB chip has also been tested for practical application and aging.

The results show that when the soldering temperature is 270°C, the void ratio of the soldering layer is only 5.1%, the junction temperature of the chip is only 76.52°C, and the luminous flux and luminous efficiency are the highest, and it has been observed that the luminous efficiency and average junction temperature of the chip are 107 lm/W and 72.3°C, respectively, which meets the requirements of street lights. After aging for 1,080 h, the light attenuation is 84.64% of the initial value, which indicates that it has higher reliability and longer life.

It can provide reference data for readers and people in this field and can be directly applied to practical engineering.

This paper aims to investigate the delamination wear properties of a carbon strip in a carbon strip rubbing against a copper wire at the high-sliding speed (380 km/h) with or without electrical current.

The friction and wear properties of a carbon strip in a carbon strip rubbing against a copper wire are tested on the high-speed wear tester whose speed can reach up to 400 km/h. The test data have been collected by the high-speed data collector. The worn surfaces of the carbon strip are observed by the scanning electron microscope.

It was found that there was a significant increase of the delamination wear with the decrease of the normal load when the electric current is applied. The size of the flake-like peeling also increases with the decrease of normal load. The delamination wear extends gradually from the edge of the erosion pits to the surrounding area with the decrease of the normal load. However, the delamination wear never appears in the absence of electric current. It is proposed that the decreased normal load and the big electrical current are the major causes of the delamination wear of the carbon strip.

The experimental test at high-sliding speed of 380 km/h was performed for the first time, and the major cause of the delamination was discovered in this paper.

The deployment of blockchain technology (BT) throughout the supply chain is usually led by large firms that dominate the supply chain. Leading firms can encourage other resource-constrained partners to get on board by providing technical and financial support. However, due to the uncertain consequences of relying on leading firms, these partners may still be reluctant to adopt BT. Drawing on resource dependence theory, this study aims to investigate whether and when supply chain alignment can be used as a dependency coping strategy to increase the willingness of resource-constrained partners to adopt BT. Moreover, it aims to examine the motivators for supply chain alignment.

This study adopted a survey research design and collected data from 364 small and medium-sized enterprises in China.

Supply chain alignment positively affects BT adoption. The effect of supply chain alignment on BT adoption is contingent on guanxi (a Chinese cultural tradition of interpersonal connections that facilitate a mutual exchange of favors). Relative advantage, technology complexity, organizational readiness and cost are motivators for supply chain alignment. Supply chain alignment mediates the effect of cost, technology complexity and relative advantage on BT adoption.

This research addresses the problem of resource dependency in the context of BT adoption which has been overlooked by previous research. Moreover, this paper enriches the BT literature by identifying supply chain alignment as an important channel for technology–organization–environment factors to influence BT adoption.

The definition and essence of a trade union is to provide a voice for the worker, enabling a balancing of the power gap between employer and employee. How does that shift in the gig economy when the worker lacks even the most basic elements of protection through employment law? This chapter interrogates the proposition that the trade union movement has until recently neglected to engage with the issues that these workers are facing and so has denied its own roots. One result of this has been the emergence of alternative forms of organising for collective voice. This shifts the boundaries between organisers of collective voice and representation with varying results. This chapter discusses the impact on trade unionism of the gig economy and critiques its approach and pace. It identifies the conflict engendered within the trade union of advocating for members only, as well as the shifting sectors in the broader economy and trade union responses to that. The importance of trade unionism moving forward is assessed through a series of interviews and secondary research using the lenses of social movement theory at macro-level, social network theory at meso-level and social identity theory at micro-level. These theories allow an interdisciplinary analysis of trade unions responses to assess the causes of responses of trade unionists to this emergent gigging workforce and its challenges. It identifies that there is a more recent intention and potential for trade unions to engage with giggers but that an innovative and international movement for voice is required.

The purpose of this paper is to provide a classificatory framework for mapping out entrepreneurs and small businesses with growth potentials in Africa.

The study undertakes a review of the existing development economics and entrepreneurship literature to determine the need for the framework and how to proceed in developing it.

The literature review informs that although enterprise-led growth provides a greater promise for absolute poverty reduction, policymakers lack guidelines on how to identify those with highest potentials for job creation and tax revenue generation. Furthermore, African entrepreneurs can purposefully be classified in terms of their motives and degree of innovation. The classification produces a 2×2 matrix that maps out the growth capabilities of businesses found in a given country or community.

The framework provides researchers and policymakers with descriptive categories that can guide their strategies and decisions.

Introducing innovation-imitation dimension into the classificatory framework extends and improves previous typologies of small enterprises available in the literature.

The purpose of this study is to solve the issues of time-consuming and complicated computation of traditional measures, as well as the underutilization of two-dimensional (2D) phase-trajectory projection matrix, so a new set of features were proposed based on the projection of attractors trajectory to characterize the friction-induced attractors and to reveal the tribological behavior during the running-in process.

The frictional running-in experiments were conducted by sliding a ball against a static disk, and the friction coefficient was collected to reconstruct the friction-induced attractors. The projection of the attractors in 2D subspace was then mapped and the distribution of phase points was adapted to conduct the feature extraction.

The evolution of the proposed moment measures could be described as “initial rapid decrease/increase- midterm gradual decrease/increase- finally stable,” which could effectively reveal the convergence degree of the friction-induced attractors. Moreover, the measures could also describe the relative position of the attractors in phase–space domain, which reveal the amplitude evolution of signals to some extent.

The proposed measures could reveal the evolution of tribological behaviors during the running-in process and meet the more precise real-time running-in status identification.

Monsters, from ghouls and zombies to shoggoths and Cthulhu, have always fascinated humans and have a prominent presence in cultural production. This is made clear by how much people enjoy Halloween events and dressing up as their favourite monster or the most recent trend of horror themed escape rooms, that include haunted houses, a zombie apocalypse or Lovecraftian monsters. Monstrous creatures represent the fears and desires of society and often embody the allure of danger, transgression and power. Monsters have long been used to construct certain images of the different/unconventional and thus represent anything diverse as the Other. Monsters, however, can be employed to invert or even overturn this relationship by empowering the Other and thus provide us with a more critical view on society in regard to our values, fears and attitudes. The stories and folklore about monsters and the monstrous that incite fear and remind us to always check under our beds before we sleep have also found their way into our everyday lives. Within the mainstream media, criminality is indicative of moral corruption, and is attributed with notions of monstrosity. These monsters do not have claws, instead, they are unpredictable, different and deviate from social and cultural norms. Like the mythical creatures in folklore, monstrosity in its human form reminds us to fear the future, the unknown, Others and society. The monstrous is centrally defined by its unfixedness, its resistance to conformity or to convenient schematic identification. It is somatically and intellectually uneasy, a restless disturbing embodied thought that unsettles, and whose greatest value to us is its very indeterminacy. This chapter illustrates the shifting shapes of the monstrous, their makers, and offers insight about what we can learn from studying these cautionary noetic chimeras. Drawing on the diversity of our academic backgrounds, ideological perspectives and the research from our individual chapters, we address the contemporary narrative of the figure of the monster. Rather than an essay style examination, our chapter explores this narrative through a question and answer format. The flexibility of this format allows readers an intimate glimpse into the ways in which the monstrous can be conceptualised and understood in various frameworks.