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Growing food demand, climate change, and constrained natural resources create the need for large-scale, sustainable agricultural intensification. Despite drip irrigation’s ability to be more water efficient than traditional irrigation technologies, its adoption and retention is limited to due to its high hydraulic equipment costs, particularly in low/middle-income countries. As a commodity product, drip emitters contribute directly to raw material costs and additionally dictate tube thickness and related material consumption. This work introduces a new empirical, deterministic design theory for creating compact, low-cost labyrinths, which are otherwise a volume-intensive component of drip irrigation emitters. To simplify design analysis a review of current commercial art, manufacturing process constraints and symmetry-based geometric relationships was conducted, resulting in the labyrinth’s tooth tip gap being selected as a key design variable. The tip gap is correlated with the hydraulic performance of a test labyrinth geometry via a Design of Experiments approach. The experiments shed light on two distinct fluid dynamic regimes in the labyrinth based on the tip gap size and provide an empirical expression between the two. This work demonstrates that simultaneous consideration of symmetry, manufacturing process and design goals enables rapid synthesis of labyrinths that are 43.77% shorter than comparable commercial designs.

As populations increase and freshwater supplies decrease, adopting water- and energy-efficient irrigation practices is crucial, particularly in resource-constrained regions. Here, farmers are often unable to purchase the equipment used in precision irrigation, a practice that implements the automatic scheduling of irrigation events to achieve high efficiency. Currently, no irrigation methods exist that combine the automatic scheduling of irrigation events with the manual operation of valves, a common practice on low-income farms. This work introduces a design concept for an automatic scheduling and manual operation (AS-MO) tool that addresses the efficiency needs of resource-constrained farms and integrates into current manual practices. However, it is unknown how farmers would value such a tool. Through interviews and focus groups facilitated by a series of storyboards and a physical prototype, the proposed concept was evaluated by farmers and key market stakeholders in Kenya, Jordan, and Morocco. Results showed that farmers in Kenya and Jordan in particular valued the proposed AS-MO concept because they want increased efficiency on their farms but did not want to install automatic valves for cost and complexity concerns. A possible market was also found in Morocco, but a majority of interviewed farms preferred automatic valve operation due to large farm sizes. Interviewees provided feedback on how to improve the tool’s design in future iterations. If adopted at scale, this AS-MO tool could increase efficiency on farms that otherwise cannot afford current precision irrigation technology, improving sustainable agriculture worldwide.

Low and middle income countries often do not have the infrastructure needed to support weather forecasting models, which are computationally expensive and often require detailed inputs from local weather stations. Local, low-cost weather prediction services are needed to enable optimal irrigation scheduling and increase crop productivity for rural farmers in low-resource settings. This work proposes a machine learning approach to predict the weather inputs needed to calculate crop water demand, namely evapotranspiration and precipitation. The focus of this work is on the accuracy with which Moroccan weather can be predicted with a vector autoregression (VAR) model compared to using typical meteorological year (TMY) weather, and how this accuracy changes as the number of weather parameters is reduced.

Food insecurity in East Africa (EA) is exacerbated by the effects of climate change. Water scarcity and high energy costs make it difficult for farmers to increase their yields to levels needed to feed growing populations. One way for countries to sustainably increase food production is to increase the adoption of water- and energy-efficient irrigation technology. Solar-powered drip irrigation systems are such a technology. These systems provide many benefits to farmers who have been able to install them on their fields, but their high costs is one barrier that currently limits its adoption among the majority of EA farmers. In this work, a concept for a novel irrigation controller is introduced and assessed for its viability in the EA market. The proposed controller determines complex irrigation schedules based on local weather predictions and specifics of a given farm. It does this while optimizing for the lifetime performance of the irrigation system, something that existing controllers do not do and something that could lower the lifetime costs of solar-powered drip irrigation systems. The proposed controller communicates this complex schedule to farmers in a way that allows them to continue to use low-cost, manually-operated valves on their fields. This concept is evaluated through storyboard-based interviews with EA farmers and key market stakeholders. The results provide initial positive feedback from these lead users, suggesting that this controller could be a viable product in EA. If adopted at scale, this technology could help lower the barrier to adopting water- and energy-efficient irrigation, ultimately having a positive, sustainable impact on food security in EA.

There is significant need for low-cost, high-performance prosthetic knees in low- and middle-income countries (LMICs) due to a large number of amputees and particularly challenging socioeconomic and environmental conditions. Prostheses are important for maintaining one’s participation in society, culture, and the economy, but many are either prohibitively expensive or do not provide near-able-bodied kinematics. Poor performing prosthetic knees cause discomfort and draw unwanted attention to transfemoral amputees. In this study, we refine the design of a high-performing, single-axis, passive prosthetic knee developed with a focus on the Indian market in order to reduce cost, weight, and part count; enhance manufacturability; and improve aesthetics. The load paths and functional componentry were critically analyzed to identify opportunities to streamline the design while maintaining strength and the near-able-bodied kinematics offered by the original design. The part count was reduced almost four-fold, and the mass of the prosthesis was reduced three-fold. An enclosure was also designed to encase the functional componentry in an aesthetically acceptable package. The changes made to the design are believed to significantly advance the usability and commercial viability of the prosthetic knee. This study may serve as an example of how products developed for emerging markets may achieve affordability without sacrificing performance.

Water scarcity is increasingly becoming a problem in India, so much so that a recently proposed piece of legislation would mandate home-scale water desalination systems to have a 60% recovery ratio [1], significantly higher than existing systems. We developed an electrodialysis-based home-scale desalination system for obtaining drinking water that will meet and surpass this new proposed recovery ratio. This project builds heavily on previous and current work by the MIT Global Engineering and Research (GEAR) Lab and was conducted with Eureka Forbes Limited (EFL), a major stakeholder in India’s home-scale desalination industry. Two critical design modules within the desalinator are explored — the system integration and fluid reversal mechanism and the electrodialysis stack end cap analysis. We developed a model framework that will output the validity of end cap designs based on established design requirements, designed fluid reversal mechanisms for distinct markets, and fabricated a prototype desalination cabinet that fits within the EFL’s design constraints. We also discuss the details of our collaboration with both academic and industrial partners, extract specific lessons learned about the lab-to-market design process, and discuss some of the specific challenges faced by a design group in our circumstances and the ways we resolved them.

AbstractThe walking pattern and comfort of a person with lower limb amputation are determined by the prosthetic foot’s diverse set of mechanical characteristics. However, most design methodologies are iterative and focus on individual parameters, preventing a holistic design of prosthetic feet for a user’s body size and walking preferences. Here we refined and evaluated the lower leg trajectory error (LLTE) framework, a novel quantitative and predictive design methodology that optimizes the mechanical function of a user’s prosthesis to encourage gait dynamics that match their body size and desired walking pattern. Five people with unilateral below-knee amputation walked over-ground at self-selected speeds using an LLTE-optimized foot made of Nylon 6/6, their daily-use foot, and a standardized commercial energy storage and return (ESR) foot. Using the LLTE feet, target able-bodied kinematics and kinetics were replicated to within 5.2% and 13.9%, respectively, 13.5% closer than with the commercial ESR foot. Additionally, energy return and center of mass propulsion work were 46% and 34% greater compared to the other two prostheses, which could lead to reduced walking effort. Similarly, peak limb loading and flexion moment on the intact leg were reduced by an average of 13.1%, lowering risk of long-term injuries. LLTE-feet were preferred over the commercial ESR foot across all users and preferred over the daily-use feet by two participants. These results suggest that the LLTE framework could be used to design customized, high performance ESR prostheses using low-cost Nylon 6/6 material. More studies with large sample size are warranted for further verification.

People with lower-limb amputation in low- and middle-income countries (LMICs) lack access to adequate prosthetic devices that would restore their mobility and increase their quality of life. This is largely due to the cost and durability of existing devices. Single-keel energy storage and return (ESR) prosthetic feet have recently been developed to provide improved walking benefits at an affordable cost in LMICs. These low-cost single-keel ESR feet were created using a novel design methodology, the lower leg trajectory error (LLTE) framework. The LLTE framework enables the optimization of the stiffness and geometry of a user’s prosthesis to match a target walking pattern. However, these low-cost single-keel ESR prostheses do not provide the required durability to fulfill the international standards organization (ISO) testing, which prevents their widespread use and adoption. In this work, we developed a multi-keel prosthetic foot parametric model, and extended the LLTE framework to include this multi-keel architecture and the durability requirements. This extended LLTE framework enabled the design of durable and low-cost multi-keel ESR prosthetic feet made of Nylon 6/6. Multi-keel foot designs were shown to provide 76% improved walking performance (lower LLTE values) compared with single-keel ESR designs. Load testing of prototype multi-keel feet validated the multi-keel constitutive model predictions used in the LLTE framework. The measured deflections of the prototypes under load were accurately described with an average error of 0.6 ± 0.4 mm (5.7 ± 4.2%). These multi-keel feet designed using the extended LLTE framework withstood ISO fatigue and static tests, validating their durability. Given their single-part 2D extruded geometries, multi-keel feet designed with the extended LLTE framework could be cost-effectively manufactured, providing affordable and durable high-performance prostheses that improves the mobility of LMIC users.

AbstractGlobally, 1.6 billion people in rural regions face water scarcity. Expanding freshwater access via brackish groundwater desalination can provide additional resources to address this challenge. In this study, we have developed a time-variant electrodialysis reversal (EDR) technology that flexibly uses available solar energy for desalination. Our proposed photovoltaic-powered desalination system can vary pumping and EDR power to match the availability of intermittent solar power, maximizing the desalination rate. Our results show improved system performance with the direct use of 77% of available solar energy—91% more than in conventional systems—and a 92% reduction in battery reliance. In a village-scale desalination case study in India, these system improvements lead to a 22% reduction in water cost, making the technology competitive with the currently used on-grid, village-scale reverse osmosis systems that are mainly powered by fossil fuels. Future advances could further reduce costs, providing an improved, sustainable solution to water scarcity in remote areas.

Humanitarian crises ranging from political unrest to natural disasters are becoming increasingly prevalent with global climate change. Correspondingly, there are an increasing number of regions that consist both of high crises risk and saline water contamination. Such regions include the Middle East, Subsaharan Africa (particularly along the Great Rift Valley), Southeast Asia (including the Mekong Delta and Pacific Islands), and coastal regions. However, there is a lack of robust, deployable desalination technologies for humanitarian crises. This is mainly attributed to the highly-constrained environment which necessitate: minimization of consumables, rapid speed of deployment and simplification of operation and maintenance. Such constraints are often secondary thoughts, are difficult to traditionally quantify, and differ from stable commercial situations where operations are supported by an accessible supply chain and network of technicians. These barriers have particularly hindered the adoption of membrane technology and thus, high volume desalination and chemical contaminant removal. This work justifies the need for desalination technology in humanitarian crises via geospatial analysis of saline water databases and exploration of regional case studies, formulates design requirements for an emergency-use desalination system based on needs extracted from open-interviews of stakeholders and literature review, evaluates some of the gaps within currently employed deployable desalination systems and explores the potential opportunities of other desalination technology.

Advances in understanding the effects the mechanical characteristics of prosthetic feet on user biomechanics have enabled passive prostheses to improve the walking pattern of people with lower limb amputation. However, there is no consensus on the design methodology and criteria required to maximize specific user outcomes and fully restore their mobility. The Lower Leg Trajectory Error (LLTE) framework is a novel design methodology based on the replication of lower leg dynamics. The LLTE value evaluates how closely a prosthetic foot replicates a target walking pattern. Designing a prosthesis that minimizes the LLTE value, optimizes its mechanical function to enable users to best replicate the target lower leg trajectory. Here, we conducted a systematic sensitivity investigation of LLTE-optimized prostheses. Five people with unilateral transtibial amputation walked overground at self-selected speeds using five prototype energy storage and return feet with varying LLTE values. The prototypes' LLTE values were varied by changing the stiffness of the participant's LLTE-optimized design by 60%, 80%, 120%, and 167%. Users most closely replicated the target able-bodied walking pattern with the LLTE-optimized stiffness, experimentally demonstrating that the predicted optimum was a true optimum. Additionally, the predicted LLTE values were correlated to the user's ability to replicate the target walking pattern, user preferences, and clinical outcomes including roll-over geometries, trunk sway, prosthetic energy return, and peak push-off power. This study further validates the use of the LLTE framework as a predictive and quantitative tool for designing and evaluating prosthetic feet.

Abstract The increasing demand for electrification in various industries has led to the need for new technology to evolve and support this shift. Manufacturers in the industrial and military market are exploring the electrification of its hydraulic actuation devices in order to improve efficiency, sustainability, and maintenance. However, replacing hydraulic actuators with electromechanical alternatives presents a significant challenge, particularly in high force, high stroke applications that require a stroke length of 2.4 m (8 ft) to 6.7 m (22 ft) and the delivery of 150 kN of force. In this paper, we present the design and scaled-prototype of an electromechanical telescoping actuator architecture that can meet these demanding requirements. The proposed design relies on screw and nut mechanisms that are engaged simultaneously in a telescoping manner and is able to achieve more than double extension of its collapsed length. Our group was able to successfully develop and evaluate the design and build a scaled-down prototype that could likely serve as a direct replacement for currently used long-stroke high-force hydraulics. The prototype was able to achieve extension from 17 cm (7 in) to 49 cm (19.2 in) with 10 s cycle time, and is able to lift at least 28 N (6.3 lbf). This work was done in partnership with Oshkosh Corporation.

The genera Ericiolus and Mercedesia are distinctive extant coccolithophores that are characterized by monothecate, monomorphic coccospheres with one type of triradiate star-shaped nannoliths. The two genera were described from the Danish coastal waters, the surface waters of the Arctic, and the Southern Oceans. During a study of samples from the low photic zone of the Mediterranean and Sargasso Seas, and from the subtropical gyres of the South-eastern Pacific and the South Atlantic Oceans, 44 collapsed coccospheres with triradiate star-like nannoliths were observed via scanning electron microscopy. Observations on the morphologies and biometric assessments of these specimens revealed that three distinct sets of nannoliths can be distinguished and that these were morphologically differentiated from all currently known species of Ericiolus and Mercedesia. The new forms and the previously described species of Ericiolus and Mercedesia were, however, similar, as they all demonstrated a distinctive set of collectively shared morphological characters and almost identical size ranges. On the basis of this, and instead of describing a third genus for the same group of nannoliths, we preferred to taxonomically synonymize Mercedesia with Ericiolus and revise the definition of Ericiolus. Therefore, we describe three new species, Ericiolus bendifii sp. nov., Ericiolus sheldoniae sp. nov. and Ericiolus mattioliae sp. nov., and an incompletely defined taxon, as Ericiolus cf. bendifii, and establish the new combinations E. aspiphorus comb. nov., E. multistellatus comb. nov. and E. pusillus comb. nov.

As solar technology has matured, irrigation using photovoltaic pumping systems (PVPSs) has gained popularity in developing markets as an effective means to alleviate poverty and increase food security. Yet, there remains a barrier to adoption; the upfront costs of PVPSs pose a financial burden for many low-income farmers. In a PVPS, the capital cost of the solar array contributes a large portion of upfront system costs. The solar pump is the largest energy consumer in the system, thus its efficiency directly impacts the size and cost of the solar array. There is a limited quantitative understanding of how solar pump efficiency affects the capital cost of the solar array. This study presents a technoeconomic framework to directly quantify the impact of solar pump efficiency on the cost of the solar array in a PVPS, for a range of hydraulic operating conditions. New empirical efficiency scaling laws were created by characterizing the efficiencies of 4-inch multistage centrifugal borehole pumps and induction motors. The utility of the technoeconomic framework is demonstrated through a case study comparing solar pump architectures with motors of different efficiencies. Results indicate that, despite the increased motor cost, the use of high-efficiency motors in solar pumps may lead to an overall cost reduction in a PVPS. Counter to the conventional capital cost-driven process, this work demonstrates that an efficiency-driven design process could improve low-cost, solar-powered system design. Engineers and system designers can leverage the presented framework during the design process to make informed decisions to achieve more cost-effective PVPSs.

Based on scanning electron microscopy observations, a new species of the coccolithophore genus Calciopappus (Syracosphaeraceae, Prymnesiophyceae) is described from the surface waters off Bergen and from the lower photic zone of sub-tropical and tropical waters. Morphological, coccolith rim structure and biometric analyses strongly support separation of this morphotype from the two described Calciopappus species, but inclusion of it within the genus. The new form differs from the other species in being noticeably smaller and in morpho-structural details of each of the three coccolith types that form the coccosphere: (1) the body coccoliths have an open central area; (2) the whorl coccoliths have a wide central opening and two thumb-like protrusions; and (3) the appendage coccoliths are curved. On this basis, the species is formally described as Calciopappus curvus sp. nov., its systematic affinity is discussed and compared with other extant coccolithophores

This study set out to identify emerging trends in advancing engineering for sustainable development, supporting the engineering workforce to address wicked problems, and strengthening pathways between engineering education, industry, and policy. The following question guided this work: What are the emerging factors impacting the future of global sustainability efforts within engineering, and how can these be amplified to increase the impact of engineering for sustainable development? Using an adapted Delphi method with surveys, focus groups, and member-checking interviews, we hosted the American Society of Mechanical Engineers (ASME) 2022 Engineering Global Development (EGD) Stakeholder Summit. The summit convened industry leaders, innovators, and academics to explore emerging factors impacting the future of global sustainability efforts in engineering. This manuscript synthesizes emerging trends and proposes recommendations for engineering, particularly in the specific focus area of engineering for sustainable development (e.g., ‘humanitarian engineering’, ‘global engineering’). Critical recommendations include the adoption of emerging cultural mindsets, which include: (1) take an interdisciplinary and multi-stakeholder approach, (2) consider dynamic and interconnected systems, (3) increase humility and intercultural competence, (4) prioritize diversity and inclusion, (5) increase localization and center community perspectives, (6) challenge the perception that engineering is neutral, and (7) broaden the goals of engineering. Ultimately, this study highlights pathways forward for the broader engineering community to more effectively contribute to advancing the United Nations Sustainable Development Goals.