Browsing by Author "Chandrakumar C"

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    Correction: Barnsley et al. Lifetime Climate Impacts of Diet Transitions: A Novel Climate Change Accounting Perspective. Sustainability 2021, 13, 5568
    (MDPI (Basel, Switzerland), 2022-07) Barnsley JE; Chandrakumar C; Gonzalez-Fischer C; Eme PE; Bourke BEP; Smith NW; Dave LA; McNabb WC; Clark H; Frame DJ; Lynch J; Roche JR
    The authors would like to make the following corrections about the published paper The changes are as follows: (1) Replacing the Conflicts of Interest: Conflicts of Interest: The authors declare no conflict of interest. with Conflict of Interest: The Ministry for Primary Industries (MPI) is the regulator for New Zealand’s entire primary sector. As regulator, we are responsive to the needs of all food-producing industries and have a wide range of other responsibilities. In a practical sense, our role includes protecting New Zealand from biological risk, increasing food production, minimising environmental impacts, and ensuring the food we produce in New Zealand is safe for consumers. The primary sector is wide-ranging and includes our arable and horticulture industries, as well as our red meat, dairy, fisheries and aquaculture industries. The authors apologize for any inconvenience caused and state that the scientific conclusions are unaffected. The original publication has also been updated.
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    Earthquake early warning systems based on low-cost ground motion sensors: A systematic literature review
    (Frontiers Media S.A, 3/11/2022) Chandrakumar C; Prasanna R; Stephens M; Tan ML
    Earthquake early warning system (EEWS) plays an important role in detecting ground shaking during an earthquake and alerting the public and authorities to take appropriate safety measures, reducing possible damages to lives and property. However, the cost of high-end ground motion sensors makes most earthquake-prone countries unable to afford an EEWS. Low-cost Microelectromechanical systems (MEMS)-based ground motion sensors are becoming a promising solution for constructing an affordable yet reliable and robust EEWS. This paper contributes to advancing Earthquake early warning (EEW) research by conducting a literature review investigating different methods and approaches to building a low-cost EEWS using MEMS-based sensors in different territories. The review of 59 articles found that low-cost MEMS-based EEWSs can become a feasible solution for generating reliable and accurate EEW, especially for developing countries and can serve as a support system for high-end EEWS in terms of increasing the density of the sensors. Also, this paper proposes a classification for EEWSs based on the warning type and the EEW algorithm adopted. Further, with the support of the proposed EEWS classification, it summarises the different approaches researchers attempted in developing an EEWS. Following that, this paper discusses the challenges and complexities in implementing and maintaining a low-cost MEMS-based EEWS and proposes future research areas to improve the performance of EEWSs mainly in 1) exploring node-level processing, 2) introducing multi-sensor support capability, and 3) adopting ground motion-based EEW algorithms for generating EEW.
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    Estimating S-wave amplitude for earthquake early warning in New Zealand: Leveraging the first 3 seconds of P-Wave
    (Springer, 2024-07-13) Chandrakumar C; Tan M; Holden C; Stephens M; Punchihewa A; Rahubadde Kankanamge R
    This study addresses the critical question of predicting the amplitude of S-waves during earthquakes in Aotearoa New Zealand (NZ), a highly earthquake-prone region, for implementing an Earthquake Early Warning System (EEWS). This research uses ground motion parameters from a comprehensive dataset comprising historical earthquakes in the Canterbury region of NZ. It explores the potential to estimate the damaging S-wave amplitude before it arrives, primarily focusing on the initial P-wave signals. The study establishes nine linear regression relationships between P-wave and S-wave amplitudes, employing three parameters: peak ground acceleration, peak ground velocity, and peak ground displacement. Each relationship’s performance is evaluated through correlation coefficient (R), coefficient of determination (R²), root mean square error (RMSE), and 5-fold Cross-validation RMSE, aiming to identify the most predictive empirical model for the Canterbury context. Results using a weighted scoring approach indicate that the relationship involving P-wave Peak Ground Velocity (Pv) within a 3-second window strongly correlates with S-wave Peak Ground Acceleration (PGA), highlighting its potential for EEWS. The selected empirical relationship is subsequently applied to establish a P-wave amplitude (Pv) threshold for the Canterbury region as a case study from which an EEWS could benefit. The study also suggests future research exploring complex machine learning models for predicting S-wave amplitude and expanding the analysis with more datasets from different regions of NZ.
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    Lifetime climate impacts of diet transitions: a novel climate change accounting perspective
    (MDPI (Basel, Switzerland), 2021-05-17) Barnsley JE; Chandrakumar C; Gonzalez-Fischer C; Eme PE; Bourke BEP; Smith NW; Dave LA; McNabb WC; Clark H; Frame DJ; Lynch J; Roche JR; Carolan M
    Dietary transitions, such as eliminating meat consumption, have been proposed as one way to reduce the climate impact of the global and regional food systems. However, it should be ensured that replacement diets are indeed nutritious and that climate benefits are accurately accounted for. This study uses New Zealand food consumption as a case study for exploring the cumulative climate impact of adopting the national dietary guidelines and the substitution of meat from hypothetical diets. The new GWP* metric is used as it was designed to better reflect the climate impacts of the release of methane than the de facto standard 100-year Global Warming Potential metric (GWP100). A transition at age 25 to the hypothetical dietary guideline diet reduces cumulative warming associated with diet by 7 to 9% at the 100th year compared with consuming the average New Zealand diet. The reduction in diet-related cumulative warming from the transition to a hypothetical meat-substituted diet varied between 12 and 15%. This is equivalent to reducing an average individual's lifetime warming contribution by 2 to 4%. General improvements are achieved for nutrient intakes by adopting the dietary guidelines compared with the average New Zealand diet; however, the substitution of meat items results in characteristic nutrient differences, and these differences must be considered alongside changes in emission profiles.
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    “Saving Precious Seconds”—A Novel Approach to Implementing a Low-Cost Earthquake Early Warning System with Node-Level Detection and Alert Generation
    (MDPI (Basel, Switzerland), 8/03/2022) Prasanna R; Chandrakumar C; Nandana R; Holden C; Punchihewa A; Becker JS; Jeong S; Liyanage N; Ravishan D; Sampath R; Tan ML
    This paper presents findings from ongoing research that explores the ability to use Micro-Electromechanical Systems (MEMS)-based technologies and various digital communication protocols for earthquake early warning (EEW). The paper proposes a step-by-step guide to developing a unique EEW network architecture driven by a Software-Defined Wide Area Network (SD-WAN)-based hole-punching technology consisting of MEMS-based, low-cost accelerometers hosted by the general public. In contrast with most centralised cloud-based approaches, a node-level decentralised data-processing is used to generate warnings with the support of a modified Propagation of Local Undamped Motion (PLUM)-based EEW algorithm. With several hypothetical earthquake scenarios, experiments were conducted to evaluate the system latencies of the proposed decentralised EEW architecture and its performance was compared with traditional centralised EEW architecture. The results from sixty simulations show that the SD-WAN-based hole-punching architecture supported by the Transmission Control Protocol (TCP) creates the optimum alerting conditions. Furthermore, the results provide clear evidence to show that the decentralised EEW system architecture can outperform the centralised EEW architecture and can save valuable seconds when generating EEW, leading to a longer warning time for the end-user. This paper contributes to the EEW literature by proposing a novel EEW network architecture.