David Littlewood

University of Sheffield

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Diane Holt

University of Leeds

Julia Plews

Sandia National Laboratories California

Timothy Shelton

Sandia National Laboratories California

Michael Veilleux

Sandia National Laboratories California

Patrick Xavier

Sandia National Laboratories

Michael Tupek

Lawrence Livermore National Laboratory

Nathan Crane

Brigham Young University

Jesse Thomas

Sandia National Laboratories

Vicki Porter

University of British Columbia

Kendall Pierson

Sandia National Laboratories

Cooperative Institutions

Sandia National Laboratories California

103

Sandia National Laboratories

Office of Scientific and Technical Information

National Technical Information Service

Los Alamos National Laboratory

Oak Ridge National Laboratory

Commissariat à l'Énergie Atomique et aux Énergies Alternatives

CEA Cadarache

Cornell University

Centre National de la Recherche Scientifique

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Conceptualizing Resilience & Social Entrepreneurship Relationships in Complex & Chaotic Environments

Academy of Management Proceedings (2015)

David Littlewood Diane Holt

This paper explores and conceptualizes the relationship between social entrepreneurship and resilience through inductive interpretation of 21 case examples of African hybrid-social enterprises. The paper is based upon observations and qualitative data collected during fieldwork in Kenya, Zambia, Mozambique and South Africa as well as analysis of secondary materials. The paper firstly explores key characteristics and traits of resilient social entrepreneurs and enterprises, before considering impact strategies for fostering stakeholder resilience. A conceptual framework emerging from the case analysis is then presented, that can be used to explore resilience in hybrid/social enterprises in the complex, chaotic and challenging institutional contexts typically found in developing countries with high levels of relative poverty and acute social problems.

Resilience

10.5465/ambpp.2015.11738abstract

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Mapping the trickle out benefits of social and environmental enterprises: a pilot study of an East African eco business

David Littlewood Diane Holt

• Objectives The objective of this paper is to propose a framework for mapping the sustainable development and poverty alleviation impacts of social and environmental enterprises in Africa. This framework is then piloted with reference to an East African Ecobusiness. • Prior Work This paper is based on data collected as part of a wider research project examining social and environmental enterprises across the 19 countries of Southern and Eastern Africa. In total, the sustainable development and poverty alleviation impacts of 20 in-depth case studies in 4 countries are being examined. • Approach Data was collected using in-depth interviews with multiple stakeholders associated with the case study business. Secondary materials were also analysed and a quantitative survey of customers undertaken. • Results In addition to their impacts on the environment, African eco businesses can also have substantial social, economic and wider poverty alleviation impacts. This paper maps the impacts of a case study East African ecobusiness, as part of developing a social and environmental enterprise impact framework for Africa and the wider developing world. In our case study, positive and negative impacts are identified, while questions are raised in relation to tradeoffs between social and environmental objectives and temporal dimensions of impact. The usefulness of existing frameworks for understanding the social, environmental and development impacts of these kinds of organisations are also considered. • Implications This paper outlines the necessity of building an African-centric impact map to capture the multi-level poverty alleviation and sustainable development impacts of social and environmental enterprise activity in developing world environments. The framework proposed also offers guidance to businesses operating in Africa about the factors that might be considered as part of their wider social and environmental responsibilities. • Value Assessing the impact of social and environmental enterprises, especially as a route to development within low income countries, is receiving increasing attention in academia and beyond. This paper presents a useful contribution to the scarce literature on social and environmental enterprises in Africa.

Environmental degradation

Source

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Meshfree Peridynamics Computations: 3D Peridigm.

David Littlewood

Peridynamics

Meshfree methods

10.2172/2001560

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The Jua Kali and the Mali-Mali: The Informal/Formal Nexus amongst Kenyan Micro Enterprises

Academy of Management Proceedings (2013)

Diane Holt David Littlewood

This paper presents a preliminary exploration of the informal/formal economy nexus and entrepreneurial processes amongst a sample of Kenyan roadside vendors who mostly operate in the informal economy. Using semi-structured interviews, data was collected from sixty street vendors across Kenya. In particular the paper focuses on the relationship between the informal and formal economy and the factors that promote formality amongst micro and small enterprises in developing countries. The paper presents a conceptualization of a potential segmentation of the informal economy, considering the implications of this in terms of base of the pyramid initiatives and the promotion of development through enterprise

Formality

Informal sector

Kenya

Promotion (chess)

Kali

10.5465/aomafr.2012.0155

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Podcast of the launch of Trickle Out Africa project at British Council Nairobi

Diane Holt David Littlewood

TRICKLE

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Sierra/SolidMechanics 4.46 User's Guide

Nathan Crane Gabriel de Frias San Le David Littlewood Mark Merewether

Sierra/SolidMechanics (Sierra/SM) is a Lagrangian, three-dimensional code for finite element analysis of solids and structures. It provides capabilities for explicit dynamic, implicit quasistatic and dynamic analyses. The explicit dynamics capabilities allow for the efficient and robust solution of models with extensive contact subjected to large, suddenly applied loads. For implicit problems, Sierra/SM uses a multi-level iterative solver, which enables it to effectively solve problems with large deformations, nonlinear material behavior, and contact. Sierra/SM has a versatile library of continuum and structural elements, and a large library of material models. The code is written for parallel computing environments enabling scalable solutions of extremely large problems for both implicit and explicit analyses. It is built on the SIERRA Framework, which facilitates coupling with other SIERRA mechanics codes. This document describes the functionality and input syntax for Sierra/SM.

Solver

Quasistatic process

Code (set theory)

10.2172/1597568

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Informal economy entrepreneurs from sub-Saharan Africa: observations from Kenya

Routledge eBooks (2014)

Diane Holt David Littlewood

Since its "open door"policy in the late 1970s, both inward foreign direct investment (IFDI) and overseas foreign direct investment (OFDI) in and from China have contributed to the country's economic growth and position in the world economic order. Respectively, investments in and from China are mainly driven by foreign multinational companies (MNCs), first in China's coastal cities (Shanghai, Guangzhou, Shenzhen, Hangzhou), then slowly moving to inland provinces (Hubei, Sichuan, Hunan) as well as through Chinese MNCs in the wider world. Following the "go out" policy since the late 1990s, China's OFDI is channelled through Chinese companies which operate in various sectors particularly in Africa, Southeast Asian countries and Latin America. Chinese companies' interests in these regions contribute to promoting China's economic development and fall more and more under the south–south cooperation framework, which brings together emerging economies and the developing world. Such internationalization of Chinese MNCs shapes the characteristics of foreign investments and world markets.

Informal sector

10.4324/9780203093146-19

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Citations (1)

Roadmap for Peridynamic Software Implementation

David Littlewood

The application of peridynamics for engineering analysis requires an efficient and robust software implementation. Key elements include processing of the discretization, the proximity search for identification of pairwise interactions, evaluation of the con- stitutive model, application of a bond-damage law, and contact modeling. Additional requirements may arise from the choice of time integration scheme, for example esti- mation of the maximum stable time step for explicit schemes, and construction of the tangent stiffness matrix for many implicit approaches. This report summaries progress to date on the software implementation of the peridynamic theory of solid mechanics. Discussion is focused on parallel implementation of the meshfree discretization scheme of Silling and Askari [33] in three dimensions, although much of the discussion applies to computational peridynamics in general.

Peridynamics

10.2172/1226115

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Citations (76)

A position-aware linear solid constitutive model for peridynamics

Journal of mechanics of materials and structures (2015)

John Mitchell Stewart Silling David Littlewood

A position-aware linear solid (PALS) peridynamic constitutive model is proposed for isotropic elastic solids.The PALS model addresses problems that arise, in ordinary peridynamic material models such as the linear peridynamic solid (LPS), due to incomplete neighborhoods near the surface of a body.Improved model behavior in the vicinity of free surfaces is achieved through the application of two influence functions that correspond, respectively, to the volumetric and deviatoric parts of the deformation.The model is position-aware in that the influence functions vary over the body and reflect the proximity of each material point to free surfaces.Demonstration calculations on simple benchmark problems show a sharp reduction in error relative to the LPS model.

Peridynamics

Position (finance)

10.2140/jomms.2015.10.539

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Citations (82)

Ductile failure X-prize.

James C. Cox G.W. Wellman John M Emery Jakob T. Ostien John Bellamy Foster

Fracture or tearing of ductile metals is a pervasive engineering concern, yet accurate prediction of the critical conditions of fracture remains elusive. Sandia National Laboratories has been developing and implementing several new modeling methodologies to address problems in fracture, including both new physical models and new numerical schemes. The present study provides a double-blind quantitative assessment of several computational capabilities including tearing parameters embedded in a conventional finite element code, localization elements, extended finite elements (XFEM), and peridynamics. For this assessment, each of four teams reported blind predictions for three challenge problems spanning crack initiation and crack propagation. After predictions had been reported, the predictions were compared to experimentally observed behavior. The metal alloys for these three problems were aluminum alloy 2024-T3 and precipitation hardened stainless steel PH13-8Mo H950. The predictive accuracies of the various methods are demonstrated, and the potential sources of error are discussed.

Tearing

Code (set theory)

10.2172/1029764

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Citations (4)