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The problem of minimizing the rank of a symmetric positive semidefinite matrix subject to constraints can be lifted to give an equivalent semidefinite program with complementarity constraints. The formulation requires two positive semidefinite matrices to be complementary. This is a continuous and nonconvex reformulation of the rank minimization problem. We develop two relaxations and show that constraint qualification holds at any stationary point of either relaxation of the rank minimization problem, and we explore the structure of the local minimizers. [ABSTRACT FROM AUTHOR]

We consider optimization problems related to the scheduling of Multi-Echelon Assembly Supply Chain (MEASC) networks that find application in the recovery from large-scale disruptive events. Each manufacturer within this network assembles a component from a series of sub-components received from other manufacturers and, due to high qualification standards, each sub-component of the manufacturer is single-sourced. Our motivating industries for this problem are defense aircraft and biopharmaceutical manufacturing. We develop scheduling decision rules that are applied locally at each manufacturer and are proven to optimize two industry-relevant global recovery metrics: (i) minimizing the maximum tardiness of any order of the final product of the MEASC network, and (ii) and minimizing the time to recover from the disruptive event. Our approaches are applied to a data set based on an industrial partner's supply chain to show their applicability as well as their advantages over Integer Programming (IP) models. The developed decision rules are proven to be optimal, faster, and more robust than the equivalent IP formulations. In addition, they provide conditions under which local manufacturer decisions will lead to globally optimal recovery efforts. These decision rules can help managers to make better production and shipping decisions to optimize the recovery after disruptions and quantitatively test the impact of different pre-event mitigation strategies against potential disruptions. They can be further useful in MEASCs with or expecting a large amount of backorders. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to present an assessment of the sustainability content of the Nigerian engineering curriculum in universities. Design/methodology/approach: Content analysis is used to generate and analyse data from three engineering documents, namely, the Benchmark Minimum Academic Standards for Engineering Programmes in Nigeria and the engineering handbooks of two Nigerian higher education institutions. Findings: The Nigerian engineering curriculum is revealed to have a low sustainability content, with environmental concepts being the most cited themes and social topics as the least stated issues. Research limitations/implications: The sustainability assessment approach adopted in the study is constrained by the question of what constitutes a sustainability syllabus. Expert-derived sustainability themes used in the study are unavoidably incomplete and may limit the conduct of an exhaustive sustainability content assessment. Practical implications: Based on the research outcome, the Council for the Regulation of Engineering in Nigeria and other stakeholders can consider ways to adequately incorporate sustainability themes in the Nigerian engineering curriculum. Originality/value: The research is an effort to determine the presence of sustainability issues in the Nigerian engineering education, which has hitherto been scarcely documented. This study provides a baseline and a rationale for sustainability education interventions in the Nigerian engineering curriculum. It also presents a methodology for analysing sustainability content in university curriculum and contributes to the continuing sustainability education discourse, especially in relation to sub-Saharan Africa. [ABSTRACT FROM AUTHOR]

Abstract Being the lifeblood of socioeconomic progress, engineering is implicated in the unprecedented challenge of sustainability. The global engineering community devised sustainable engineering as a conceptual departure from conventional engineering practices. However, the extent to which the sustainability worldview has permeated the Nigerian engineering community remains unanswered. This paper is an attempt to answer the question of how sustainability literate are the members of the Nigerian engineering community. The paper undertakes an assessment of the sustainability literacy of the community with the aid of a stakeholder survey and a devised sustainability literacy test. Three criteria that are used to gauge the stakeholders' sustainability literacy are awareness of the UN Decade of Education for Sustainable Development, score on the sustainability literacy test, and self-assessment of sustainability knowledge. Survey participants were recruited mainly from two federally-run Nigerian higher education institutions, and engineering professional associations. The assessment reveals an unsatisfactory performance of the Nigerian engineering stakeholders on all three sustainability literacy criteria. The results show that the majority of the students (81%), educators (67%), and practitioners (64%) were unaware of the UNDESD. The paper therefore highlights the need to improve the sustainability literacy of the Nigerian engineering community, possibly through a sustainability education intervention. [ABSTRACT FROM AUTHOR]

Peer-to-peer logistics platforms coordinate independent drivers to fulfill requests for last mile delivery and ridesharing. To balance demand-side performance with driver autonomy, a new stochastic methodology provides drivers with a small but personalized menu of requests to choose from. This creates a Stackelberg game, in which the platform leads by deciding what menu of requests to send to drivers, and the drivers follow by selecting which request(s) they are willing to fulfill from their received menus. Determining optimal menus, menu size, and request overlaps in menus is complex as the platform has limited knowledge of drivers' request preferences. Exploiting the problem structure when drivers signal willingness to participate, we reformulate our problem as an equivalent single-level Mixed Integer Linear Program (MILP) and apply the Sample Average Approximation (SAA) method. Computational tests recommend a training sample size for inputted SAA scenarios and a test sample size for completing performance analysis. Our stochastic optimization approach performs better than current approaches, as well as deterministic optimization alternatives. A simplified formulation ignoring 'unhappy drivers' who accept requests but are not matched is shown to produce similar objective values with a fraction of the runtime. A ridesharing case study of the Chicago Regional transportation network provides insights for a platform wanting to provide driver autonomy via menu creation. The proposed methods achieved high demand performance as long as the drivers are well compensated (e.g., even when drivers are allowed to reject requests, on average over 90% of requests are fulfilled when 80% of the fare goes to drivers; this drops to below 60% when only 40% of the fare goes to drivers). Thus, neither the platform nor the drivers benefit from low driver compensation due to its resulting low driver participation and thus low request fulfillment. Finally, for the cases tested, a maximum menu size of 5 is recommended as it produces good quality platform solutions without requiring much driver selection time. • Drivers in ridesharing/crowdsourced delivery platforms autonomously make selections. • A special case yields single-level MILP equivalent to bilevel model. • Personalized driver menus are optimized for drivers' stochastic selections. • Platform benefits from offering multiple items to drivers with stochastic selection. • Computational study provides menu and performance insights. [ABSTRACT FROM AUTHOR]

Remote focusing is widely used in 3D two-photon microscopy and 3D photostimulation because it enables fast axial scanning without moving the objective lens or specimen. However, due to the design constraints of microscope optics, remote focus units are often located in non-telecentric positions in the optical path, leading to significant depth-dependent 3D field distortions in the imaging volume. To address this limitation, we characterized 3D field distortions arising from non-telecentric remote focusing and present a method for distortion precompensation. We demonstrate its applicability for a 3D two-photon microscope that uses an acousto-optic lens (AOL) for remote focusing and scanning. We show that the distortion precompensation method improves the pointing precision of the AOL microscope to < 0.5 µm throughout the 400 × 400 × 400 µm imaging volume., Competing Interests: A.M.V., F.C.N., J.E.M declare no competing interests. P.A.K. and R.A.S. are named inventors on patents owned by UCL Business relating to linear and nonlinear AOL 3D laser scanning technology. P.A.K. has a financial interest in Agile Diffraction Ltd., which aims to commercialize the AOL technology., (Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.)