Strategies of Sino-American Rivalry in Africa: From 2000 to COVID-19

In this article it is argued that Sino-American rivalry in Africa is based on competing strategies utilized by each power to enhance their interests and bilateral ties on the continent, as well to try and outdo each other in image projection and overall influence expansion. These strategies of rivalry and power enhancement revolve around promoting close military ties and transactions on the continent; the framing of the continent in the language of securitization and strategic importance; and the perennial utilization of discourse or narrative that frames the other as detrimental to the interests of African states. These strategies of containing the others power preponderance or influence have expanded to include what is now referred to as vaccine diplomacy on the part of China, and during the Trump Administration the raising of loud alarm bells of China trying to dispossess Africa through what could be referred to as the debt trap. The consequences of these competing strategies enhance the following: authoritarianism in some key African states; increased jihadism in some regions of Africa as a reaction to the presence of the two major powers on the continent; weapons implicated in state violence and war crimes; and less money available for development as a result of resources being diverted to militarization. The ongoing pandemic will add another dimension to the US - China rivalry as both powers try to project an image of being the most concerned about Africa on as it relates to combating the virus.

The vertical image projection method for migration stretch compensation

True amplitude inversion is often carried out without taking into account migration distortions to the wavelet. Seismic migration leaves a dip-dependent effect on the wavelet that can cause significant inaccuracies in the inverted impedances obtained from conventional inversion approaches based on 1D vertical convolutional modelling. Neglecting this effect causes misleading inversion results and leakage of dipping noise and migration artifacts from higher frequency bands to the lower frequencies. I have observed that despite dip-dependency of this effect, low-dip and flat events may also suffer if they are contaminated with cross-cutting noise, steep migration artifacts, and smiles. In this paper I propose an efficient, effective and reversible data pre-conditioning approach that accounts for dip-dependency of the wavelet and is applied to migrated images prior to inversion. My proposed method consists of integrating data with respect to the total wavenumber followed by the differentiation with respect to the vertical wavenumber. This process is equivalent to applying a deterministic dip-consistent pre-conditioning that projects the data from the total wavenumber to the vertical wavenumber axis. This preconditioning can be applied to both pre- and post-stack data as well as to amplitude variation with offset (AVO) attributes such as intercept and gradient before inversion. The vertical image projection methodology that I propose here reduces the impact of migration artifacts such as cross-cutting noise and migration smiles and improves inverted impedances in both synthetic and real data examples. In particular I show that neglecting the proposed pre-conditioning leads to anomalously higher impedance values along the steeply dipping structures.

Analysis of the Compression Behaviour of Reinforced Photocurable Materials Used in Additive Manufacturing Processes Based on a Mask Image Projection System

Mask image projection based on stereolithography is an additive manufactured technology based on a Frontal Photopolymerization Process. Therefore, photocurable resins are used to build-up parts layer by layer. In this paper, alumina particles have been used as a reinforcement filler in order to improve the material stress-strain behaviour. In addition, the increment of the photoconversion ratio is a key factor to enhance the mechanical properties. Consequently, a numerical model has been used to determine the optimal printing parameters to enhance the elastic mechanical properties of printed parts according to the characteristics of photocurable materials. Stable and homogeneous reinforced materials have been obtained with an alumina content ranging from 5 to 15 wt%. Furthermore, the compression behaviour of reinforced materials has been analysed by means of experimental tests. The results show an enhancement of mechanical properties after the addition of reinforcement fillers, obtaining a maximum improvement in 10 wt% of solid load content. Finally, the influence of the sample’s orientation on the construction platform has been discussed.

Film and Performance: Intermedial Intersections

Film and performance have always been closely interconnected, from the origins of cinematic projection in 1895. This essay, with a theoretical focus, explores how film and moving-image forms work to transform performance when they intersect with it, and vice versa. It examines how film serves to mediate and ‘reframe’ the experience and the time of live performance events, notably through the incorporation of moving-image elements into the space of performance, and through particular forms of projection and audience perception. It also probes how conceptions of intermediality can be traced specifically through the intersection of film and performance. The essay spans the entirety of moving image culture, beginning with an account of the connections between film and performance in the work of the German innovators of moving-image projection, the Skladanowsky Brothers, and ending with an examination of the work of the contemporary Lebanese filmmaker and performance artist, Rabih Mroué, whose work resonates with early cinema’s performative strategies but focuses also on current digital media events such as the dangerous ‘performative’ public filming with iPhones of government snipers in the streets of Syria.