Dynamic Analysis and Modeling of Jansen Mechanism

AbstractTheo Jansen mechanism is gaining wide spread popularity among legged robotics researchers due to its scalable design, energy efficiency, low payload to machine load ratio, bio-inspired locomotion, deterministic foot trajectory among others. In this paper, we present dynamic analysis of a four legged Theo Jansen link mechanism using projection method that results in constraint force and equivalent Lagrange's equation of motion necessary for any meaningful extension and/or optimization of this niche mechanism. Numerical simulations using MaTX is presented in conjunction with the dynamic analysis. This research sets a theoretical basis for future investigation into Theo Jansen mechanism

Total material requirement for the global energy transition to 2050: A focus on transport and electricity

© 2019 The Author(s) Global energy transitions could fundamentally change flows of both minerals and energy resources over time. It is, therefore, increasingly important to holistically and dynamically capture the impacts of large-scale energy transitions on resource flows including hidden flows such as mine waste, as well as direct flows. Here we demonstrate a systematic model that can quantify resource flows of both minerals and energy resources under the energy transition by using stock-flow dynamics and the concept of Total Material Requirement (TMR). The proposed model was applied to the International Energy Agency's scenarios up to 2050, targeting 15 electricity generation and 5 transport technologies. Results indicate that the global energy transition could increase TMR flows associated with mineral production by around 200–900% in the electricity sector and 350–700% in the transport sector respectively from 2015 to 2050, depending on the scenarios. Such a drastic increase in TMR flows is largely associated with an increased demand for copper, silver, nickel, lithium and cobalt, as well as steel. Our results highlight that the decarbonization of the electricity sector can reduce energy resource flows and support the hypothesis that the expansion of low-carbon technologies could reduce total resource flows expressed as TMR. In the transport sector, on the other hand, the dissemination of Electric Vehicles could cause a sharp increase in TMR flows associated with mineral production, which could offset a decrease in energy resource flows. Findings in this study emphasize that a sustainable transition would be unachievable without designing resource cycles with a nexus approach

Global Metal Use Targets in Line with Climate Goals.

Metals underpin essential functions in modern society, yet their production currently intensifies climate change. This paper develops global targets for metal flows, stocks, and use intensity in the global economy out to 2100. These targets are consistent with emissions pathways to achieve a 2 °C climate goal and cover six major metals (iron, aluminum, copper, zinc, lead, and nickel). Results indicate that despite advances in low-carbon metal production, a transformative system change to meet the society's needs with less metal is required to remain within a 2 °C pathway. Globally, demand for goods and services over the 21st century needs to be met with approximately 7 t/capita of metal stock-roughly half the current level in high-income countries. This systemic change will require a peak in global metal production by 2030 and deep decoupling of economic growth from both metal flows and stocks. Importantly, the identified science-based targets are theoretically achievable through such measures as efficient design, more intensive use, and longer product lifetime, but immediate action is crucial before middle- and low-income countries complete full-scale urbanization

A novel approach to gait synchronization and transition for reconfigurable walking platforms

Legged robots based on one degree-of-freedom reconfigurable planar leg mechanisms, that are capable of generating multiple useful gaits, are highly desired due to the possibility of handling environments and tasks of high complexity while maintaining simple control schemes. An essential consideration in these reconfigurable legged robots is to attain stability in motion, at rest as well as while transforming from one configuration to another with the minimum number of legs as long as the full range of their walking patterns, resulting from the different gait cycles of their legs, is achieved. To this end, in this paper, we present a method for the generation of input joint trajectories to properly synchronize the movement of quadruped robots with reconfigurable legs. The approach is exemplified in a four-legged robot with reconfigurable Jansen legs capable of generating up to six useful different gait cycles. The proposed technique is validated through simulated results that show the platform׳s stability across its six feasible walking patterns and during gait transition phases, thus considerably extending the capabilities of the non-reconfigurable design

Consumption in the G20 nations causes particulate air pollution resulting in two million premature deaths annually

G20の消費がPM2.5の排出を通じて年200万人の早期死亡者を生むことを推計. 京都大学プレスリリース. 2021-11-05.Worldwide exposure to ambient PM₂.₅ causes over 4 million premature deaths annually. As most of these deaths are in developing countries, without internationally coordinated efforts this polarized situation will continue. As yet, however, no studies have quantified nation-to-nation consumer responsibility for global mortality due to both primary and secondary PM2.5 particles. Here we quantify the global footprint of PM₂.₅-driven premature deaths for the 19 G20 nations in a position to lead such efforts. G20 consumption in 2010 was responsible for 1.983 [95% Confidence Interval: 1.685–2.285] million premature deaths, at an average age of 67, including 78.6 [71.5–84.8] thousand infant deaths, implying that the G20 lifetime consumption of about 28 [24–33] people claims one life. Our results indicate that G20 nations should take responsibility for their footprint rather than focusing solely on transboundary air pollution, as this would expand opportunities for reducing PM2.5-driven premature mortality. Given the infant mortality footprint identified, it would moreover contribute to ensuring infant lives are not unfairly left behind in countries like South Africa, which have a weak relationship with G20 nations

Sustainable energy transitions require enhanced resource governance

The global transition to fundamentally decarbonized electricity and transport systems will alter the existing resource flows of both fossil fuels and metals; however, such a transition may have unintended consequences. Here we show that the decarbonization of both the electricity and transport sectors will curtail fossil fuel production while paradoxically increasing resource extraction associated with metal production by more than a factor of 7 by 2050 relative to 2015 levels. Importantly, approximately 32–40% of this increase in resource extraction is expected to occur in countries with weak, poor, and failing resource governance, indicating that the impending mining boom may result in severe environmental degradation and unequal economic benefits in local communities. A suite of circular economy strategies, including lifetime extension, servitization, and recycling, can mitigate such risks, but they may not fully offset the growth in resource extraction. Our findings underscore the importance of institutional instruments that enhance the resource governance of entire low-carbon technology supply chains, along with circular economy practices. In the absence of such actions, the decarbonization of electricity and transport sectors may pose an ethical conundrum in which global carbon emissions are reduced at the expense of an increase in socio-environmental risks at local mining sites

Clarifying Demographic Impacts on Embodied and Materially Retained Carbon toward Climate Change Mitigation

Modern lifestyles demand a number of products derived from petroleum-based sources that eventually cause carbon emissions. The quantification of lifestyle and household consumption impacts upon carbon emissions from both the embodied CO2 (EC) and materially retained carbon (MRC) viewpoints is critical to deriving amelioration policies and meeting emission reduction goals.This study, for the first time, details a methodology to estimate both EC and MRC for Japan, focusing on petrochemicals and woody products utilizing the time series input-output table, physical value tables and the national survey of family income and expenditure, leveraging time series input-output-based material flow analysis (IO-MFA), and structural decomposition analysis (SDA).Findings elucidated hot spots of deleterious consumption by age of householder and the critical factors which underpin them including intensity effects, pattern effects, and demographic shifts over time. Although demographic shifts associated with an aging,shrinking population in Japan decreased EC and MRC, the negative effect reduced in size over time during 1990?2005. Policy implications identify the potential to mitigate approximately 21% of required household emission reductions by 2030 through strategies including recycling initiatives and the recovery of carbon from products covered within current recycling laws and hot spot sectors which are not currently considered such as apparel

Critical material management for sustainable transition

Industrial Ecolog

Solar powered charge stations for electric vehicles

Every hour, the sun emits more energy onto the Earth’s surface than our entire world population uses in one year. [1] Solar power provides us with the possibility of a cleaner and more renewable future. Global climate change as a result of greenhouse gases and the effects of low air quality caused by pollutants have become very substantial issues in our world today. The costs associated with greenhouse gas and air pollutant emissions, and the effect they have on human lives and human health, are major and growing concerns. The development and installation of solar powered charging stations will reduce the amount of greenhouse gases emitted into the atmosphere, future costs associated with climate change, and health issues. Thus, there is environmental, social, and economic value associated with the installation of solar powered charge stations. Solar powered charging stations have the potential of significantly reducing air pollutants and improving urban air quality. The electrification of transportation and the use of solar powered charging stations as an electricity source will improve people’s quality of life

Global copper cycles and greenhouse gas emissions in a 1.5 °C world

Moving towards a 1.5 °C world could fundamentally alter the future copper cycle through two key drivers: the implementation of decarbonization technologies and the imposition of an emissions budget on production activities. This study explores the impact of these drivers on the global copper cycle using a dynamic material flow analysis, coupled with an optimization technique. The results show that global final demand for copper could increase by a factor of 2.5 between 2015 and 2050, reaching 62 million metric tons, with approximately 4% of the increase coming from copper used in renewable energy-based power plants and 14% coming from electric vehicles. While there are sufficient resources to meet this growing demand, the greenhouse gas emissions of the copper cycle could account for approximately 2.7% of the total emissions budget by 2050, up from 0.3% today. Assessment of possible mitigation efforts by the copper industry shows that this can be halved, but will still be 35% short of the emissions budget target based on proportional responsibility, i.e., applying the same mitigation rate to all sectors. Rather, collective action is required by all stakeholders interacting with the copper cycle to bridge the mitigation gap, including through efforts to drive advanced sorting, higher fabrication yields, extended product lifetimes, and increased service efficiency of in-use copper stock