Total Footprint Research Articles

Achieving conservation targets by jointly addressing climate change and biodiversity loss

AbstractUnprecedented rates of climate change and biodiversity loss have galvanized efforts to expand protected areas (PAs) globally. However, limited spatial overlap between the most important landscapes for mitigating climate change and those with the highest value for biodiversity may impede efforts to simultaneously address both issues through new protections. At the same time, there is a need to understand how lands with high conservation value align with existing patterns of land management, both public and private, which will inform strategies for developing new conservation areas. To address these challenges, we developed three composite indices to identify the highest conservation value lands across the conterminous United States (CONUS) and Alaska, drawing on a suite of key ecological and environmental indicators. Two indices characterize the most important conservation lands for addressing climate change (based on climate accessibility, climate stability, and total carbon storage) and biodiversity (based on species richness, ecological integrity, and ecological connectivity), while a third, combined index simultaneously addresses both conservation challenges. We found that existing PAs in the United States have relatively low overlap with the highest conservation value lands, regardless of the index used (10%–13% in CONUS, 27%–34% in Alaska), suggesting limited effectiveness of current protections but substantial opportunity for expanding conservation into high‐value, unprotected areas. In unprotected landscapes, the highest value lands for addressing climate change generally diverged from those identified as most important for protecting biodiversity (22%–38% overlap, depending on index and geography). Our combined index reconciled these spatial trade‐offs through high overlap with both the climate and biodiversity indices (66%–72%). Of the unprotected high conservation value lands identified by each of our three indices, we found ≥70% are privately managed in CONUS, while 16%–27% are privately managed in Alaska, underscoring the need to engage private landowners and land trusts in efforts to substantially increase the total footprint of conservation lands in the United States. Our findings highlight the importance of balancing climate and biodiversity objectives when identifying new lands for conservation and provide guidance on where to target new protections to simultaneously address both goals. To facilitate planning using the indices, we developed an interactive web application.

Gastrointestinal endoscopy's carbon footprint.

Climate change is a global emergency. Consequently, current global targets to combat the climate crisis include reaching net-zero carbon emissions by 2050 and keeping global temperature increases below 1.5 ˚C. In 2014, the healthcare carbon footprint was 5.5% of the total national footprint. Gastrointestinal endoscopy (GIE) has a large carbon footprint compared to other procedures performed in healthcare facilities. GIE was identified as the third largest generator of medical waste in healthcare facilities for the following reasons: (1) GIE is associated with high case volumes, (2) GIE patients and relatives travel frequently, (3) GIE involves the use of many nonrenewable wastes, (4) single-use devices are used during GIE, and (5) GIE is frequently reprocessed. Immediate actions to reduce the environmental impact of GIE include: (1) adhering to guidelines, (2) implementing audit strategies to determine the appropriateness of GIE, (3) avoiding unnecessary procedures, (4) using medication rationally, (4) digitalization, (5) telemedicine, (6) critical pathways, (7) outpatient procedures, (8) adequate waste management, and (9) minimizing single-use devices. In addition, sustainable infrastructure for endoscopy units, using renewable energy, and 3R (reduce, reuse, and recycle) programs are necessary to reduce the impact of GIE on the climate crisis. Consequently, healthcare providers need to work together to achieve a more sustainable future. Therefore, strategies must be implemented to achieve net-zero carbon emissions in the healthcare field, especially from GIE, by 2050.

Toxicity Impact Assessment of Nitrogen Oxide and Sulfur Dioxide Emissions in China’s Textile Industry With Chemical Footprint Method

Emissions of air pollutants cause adverse impacts on human health and the environment. As typical air pollutants, nitrogen oxide and sulfur dioxide cause acid rain and particulate matter (PM). Significant emissions of nitrogen oxide and sulfur dioxide in the production phases make the textile industry face tremendous challenges. Determining the chemical footprint is an effective method for transforming the potential environmental risks of pollutant emissions into an intuitive form of toxicity. In this study, we adopted the chemical footprint method to assess the toxicity impact of nitrogen oxide and sulfur dioxide emissions from China’s textile industry. The results indicate that the chemical footprint of nitrogen oxide and sulfur dioxide in China’s textile industry showed a significant decreasing trend from 2001 to 2019, and the chemical footprint of nitrogen oxide was about 11 times higher than that of sulfur dioxide. Among the three sub-sectors of China’s textile industry, the textile manufacturing sector had the highest chemical footprint, accounting for 57.1–65.7% of the total chemical footprint. The remaining chemical footprint is allocated to the chemical fibers manufacturing sector, and the textile wearing apparel, footwear, and cap manufacturing sector. The chemical footprint intensity of China’s textile industry also showed a decreasing trend from 2006 to 2015, and the chemical footprint intensity of the three sub-sectors was in the order of the chemical fibers manufacturing sector, the textile manufacturing sector, and the textile wearing apparel, footwear, and cap manufacturing sector.

Trends in household demand and greenhouse gas footprints in Germany: Evidence from microdata of the last 20 years

This paper quantifies changes in the trend of greenhouse gas footprints associated with household consumption covering a period of 20 years. We combine greenhouse gas emissions related to the supply chain (embedded) and consumption (direct) with households' consumption expenditures from the sample survey of income and expenditure (EVS), and present the first comprehensive study on trends in greenhouse gas footprints of German households. We find a decay in changes in GHG footprints as a response to increases in household expenditure over time. In addition, our estimated own-price elasticities for electricity and heating indicate an increasing demand response to higher energy prices. However, this does not translate to a clear decreasing trend in the total GHG footprint because of the role of changes in the demand of other commodities and changes in expenditure levels across years. Further, comparing results of the more advanced EASI demand system with those of the more widely used QUAIDS approach, we find sizable differences.

Alfalfa and maize intercropping enhances soil nematode structure and food web complexity in low-nitrogen soils

Soil nematodes play key roles in soil ecosystem processes and functions. Although agricultural practices such as intercropping and nitrogen (N) fertilization are known to have a strong influence on soil nematodes, less is known about the responses of the soil nematode community to the combined effects of intercropping and N fertilization. This study was conducted to test whether the intercropping of maize and alfalfa can enhance the nematode community and quantified the effects of intercropping and N fertilization on nematode abundance, diversity, and metabolic footprints compared with soils under monoculture systems. An experiment involving maize and alfalfa was conducted in a 2 × 3 factorial completely randomized block design with four replications. The factors consisted of two N levels, namely, no N fertilization and N fertilization (225 kg N ha−1 yr−1), and three cropping modes: monoculture maize, monoculture alfalfa and maize intercropped with alfalfa. The results showed that, compared with the monoculture systems, intercropping increased total nematode and omnivore–predator abundances but reduced herbivore abundance. The total nematode biomass and metabolic footprint of omnivores and predators significantly increased in the intercropping treatments, regardless of N fertilization. The soil food web in the intercropping system without N fertilization was mature, structured, and enriched, as indicated by high maturity, structure and enrichment index values. However, all these effects decreased in the monoculture treatments, particularly after N fertilization. These results indicated that, compared with the monoculture systems, maize/alfalfa intercropping in low-N soil can improve the structural complexity of the soil food web. The observed complexity was attributed to the high soil moisture content, soil organic carbon and total N under the intercropping and low-N conditions. Therefore, this study provides a promising way to improve soil health and ecosystem stability, revealing that alfalfa intercropping in low-N soils can improve resource flow in the soil food web through the increase in total nematode biomass and the metabolic footprints of nematodes.

The Ecological Footprint of Greek Citizens: Main Drivers of Consumption and Influencing Factors

The Ecological Footprint (EF) is undoubtedly an important tool for calculating humans’ impact on the environment. For this tool to be even more accessible and understood by most of the people, many online ecological footprint calculators have been created, the most reliable of which was developed by Global Footprint Network (GFN). Aim of this study is to present the Greek population’s main drivers of consumption patterns after customizing the GFN’s international online calculator to the Greek statistics and national accounts. Moreover, the goal of this study is to assess the factors influencing the Ecological Footprint of Greek citizens. The development of a Greek-specific calculator was based on long-lasting research that included gathering and analyzing information about the Greek population. Five hundred seventy-four Greeks used the calculator after its adaptation, and data were collected regarding their total ecological footprint and its differentiation by land type and by consumption category. According to the results, Greece has a low mean of ecological footprint in comparison to other European countries, but there is still a lot of ground to cover for achieving a truly acceptable sustainable way of living. Additionally, only the variable of gender seems to affect the ecological footprint of Greeks, with females having significantly lower personal EF (M = 3.37) than males (M = 4.36, p = 0.011). The adapted online calculator and the produced results regarding the EF of Greek citizens are considered as a valuable tool for policy makers, stakeholders, and educational institutions.

Environmental protection tax superseded pollution fees, does China effectively abate ecological footprints?

This paper constructs the ecological footprint accounts for 30 provinces in China, and explores the effects of environmental policies from the perspective of various ecological footprints. We innovatively focus on the impact which pollution fees superseded environmental protection tax on ecological footprints. The effects of these two environmental policies in China is compared with the panel smooth transition regression model (PSTR). In comparison with pollution fees, environmental protection tax has a stronger inhibition on ecological footprints. Pollution fees can lessen the cropland's ecological footprint, but this negative effect presents marginal diminishing. As for the ecological footprints of fishing grounds and fossil energy land, when pollution fees exceed 2.002 and 2.011 (‱ of GDP) respectively, there will be a restraining effect. Pollution fees has no effect on reducing the ecological footprints of grazing land, forest land, infrastructure, and the total. The environmental protection tax has a negative impact of linearity on the ecological footprints of fishing grounds and forest land. When environmental protection tax exceeds the corresponding thresholds (1.226, 3.482, 1.867 and 3.083), it will decrease the ecological footprints of grazing land, infrastructure, fossil energy land, and the total. The negative effect of environmental protection tax on cropland's ecological footprint is not obvious. Further, the change charts of influence coefficient on ecological footprints are drawn to directly reflect the optimal tax range for environmental protection tax to diminish ecological footprints. The heterogeneity analysis reveal that the current environmental protection tax only inhibits the total ecological footprint of eight provinces, mostly in northern China. These conclusions have reference significance for the government to adjust the appropriate environmental protection tax rate.

Carbon and energy footprint analysis of Hungarian transportation activities using a multi-region input-output model

The Hungarian transport sector plays a significant role in economic development. Inland transport, air transport, and water transport are the main three modes of moving people and goods in Hungary. Therefore, these three modes affect the environment by contributing a significant amount of carbon and energy footprint. In the literature, there is no such study that identifies the environmental impacts of the Hungarian transport sector. Therefore, the lifecycle-based carbon and energy footprint impacts of Hungarian transport practices were assessed in this study, which took into account international trading links with the rest of the world. The Hungarian economy was modeled as part of a multi-region input-output (MRIO) life cycle evaluation system, which included 40 major economies, including the Hungarian, United States, China, Russia, and others and the rest of the world (ROW) nations. According to the WIOD database definition, each country's economy comprises 35 major industries. The global system of the world economy is equalized by a total of 1435 sectors (41 × 35 = 1435). The method is unique in that the MRIO model was constructed in a stochastic manner, taking into account global trade-related uncertainties. Using data mining and predictive simulation methods, the investigation focused on top carbon-emitting and energy-consuming sectors and countries. The outcome illustrated that Hungary has the highest overall carbon footprint (CFP) and total energy footprint (EFP) contributions, respectively, with 59.94% and 45.18%. Furthermore, the inland transportation market and electricity, gas, and water supply were found to be the most dominant industries in terms of overall CFP, accounting for 46.32% and 18.35%, respectively. With 34.64% of the overall effects, the coke/refined petroleum/nuclear fuel market has the highest proportion of the total energy footprint. The transportation sector has a significant role in the Hungarian economy because of the unique geographic location of the country. In another word, road and train modes are considered the dominant mode of moving goods in Hungary. Therefore, the inland transportation market is the highest contributor sector to the total share of CFP and ranked second in sharing the EFP.

Research on ecological compensation in Anhui Province of China based on ecological footprint and ecosystem service value

As an "ecological barrier", Anhui Province of China plays an important ecological role in the construction of ecological integration in the Yangtze River Delta. Taking Anhui Province of China as the research object, this paper quantitatively analyzes the status of various ecosystems, analyzes the factors affecting the balanced development of ecology and economy, and provides a basis for Anhui Province to coordinate local interests and protect the ecological environment. Specific results: (1) In 2019, the total value of ecosystem services in Anhui Province was 509.287 billion yuan. Water area, forest and grassland are the key ecosystems to be protected. (2) In 2019, the total ecological footprint of Anhui Province far exceeded the total ecological carrying capacity, and the ecological environment was in an unsustainable state of development. (3) The ecological overload index of Anhui Province in 2019 was - 7.85, which was a serious overload. The amount of ecological compensation payable was about 2302.436 billion yuan.

A review of sustainability concerns in the use of blockchain technology: Evidence from the agri-food and the pharmaceutical sectors

Blockchain is an evolving technology with promising applications in various sectors. The introduction of blockchain in the industry has the potential to provide a significant competitive advantage, even though it still is in the early stages of its adoption, particularly in supply chains. The implementation of blockchain technologies affects all the operational aspects of a production and supply chain system, including its sustainable performance. In these terms, there is a raising of concerns regarding the impact of the integration of blockchain on the economic viability of the organization, the total environmental footprint that results from its use, and the social matters regarding its control, safety assurance, and governance. The scope of this paper is to identify the implications of the integration of blockchain technologies in the industry concerning the three main pillars of sustainability.

Greenhouse gas emission inventory of Can Tho City using Bilan Carbone method

Greenhouse gas (GHG) emission inventory has always been considered a crucial first step towards any development of climate change mitigation plans and measures. In this paper, the Bilan Carbone (Carbon Balance) version 6, an easy-to-use Excel-based GHG inventory tool developed by the French Environment and Energy Management Agency, is used to make an inventory of GHG emissions generated within Can Tho City’s territory. The data used for the direct and indirect GHG emissions were collected from Can Tho City’s 2020 Statistical Yearbook, relevant businesses, and administrative units. Ten sectors, namely Energy Industry, Industrial Processes, Tertiary Sector, Residential Sector, Agriculture and Fishing, Transporting Goods, Travel by People, Construction and Highways, End-of-life Waste, and Food, were taken into account for the related analysis. Considering all GHGs cited in the Kyoto Protocol coupled with emission factors updated for Vietnam and the magnitude of emission sources, we found out that the total GHG emission of Can Tho City in 2020 is 4,311,952 tons of CO2 equivalent (CO2e) with an average of approximately 3.5 tons of CO2e per capita. Residential Sector, Industrial Processes, and Travel by People contribute the most to the total GHG footprint of the city, in which Residential Sector accounts for the largest share (743,346 tons of CO2e, making up 17.2% of the total GHG emission). Industrial Processes ranks second with 727,504 tons of CO2e (representing 16.9%), and Travel by People is third with 619,823 tons of CO2e, accounting for 14.4%. Some scientific and realistic interpretations of such sectorial findings are also provided to facilitate the next step of initiating and carrying out associated GHG mitigation measures for the city.

Net-Zero Target and Emissions from Land Conversions: A Case Study of Maryland’s Climate Solutions Now Act

Many climate change “solution” plans include net-zero goals, which involve balancing the anthropogenic greenhouse gas emissions (GHG) with their removal. Achieving net-zero goals is particularly problematic for soils because they are often excluded from GHG inventories and reduction plans. For example, Maryland’s Climate Solutions Now Act (Senate Bill 528) put forward the goal of lowering emissions of GHG to 60% under 2006 quantities by 2031 and with a target of net-zero emissions by 2045. To achieve these goals, the state of Maryland (MD) needs to quantify GHG emissions from various sources contributing to the state’s total emissions footprint (EF). Soils are currently excluded from MD’s GHG assessments, which raises a question about how the soil impacts the net-zero goal. This study examines the challenges in meeting net-zero goals using an example of carbon dioxide (CO2) as one of the GHG types (net-zero CO2 emissions). The current study quantified the “realized” social costs of CO2 (SC-CO2) emissions for MD from new land developments in the period from 2001 to 2016 which caused a complete loss of 2.2 × 109 kg of total soil carbon (TSC) resulting in $383.8M (where M = million, USD = US dollars). All MD’s counties experienced land developments with various emissions and SC-CO2 monetary values. Most of the developments, TSC losses, and SC-CO2 occurred near the existing urban areas of Annapolis and Baltimore City. These emissions need to be accounted for in MD’s GHG emissions reduction plans to achieve a net-zero target. Soils of MD are limited in recarbonization capacity because 64% of the state area is occupied by highly leached Ultisols. Soil recarbonization potential is further reduced by urbanization with Prince George’s, Montgomery, and Frederick counties experiencing the highest increases in developed areas. In addition, projected sea-level rises will impact 17 of MD’s 23 counties. These losses will generate additional social costs because of migration, costs of relocation, and damages to infrastructure. The state of MD has a high proportion of private land ownership (92.4%) and low proportion of public lands, which will limit opportunities for relocation within the state. Net-zero targets are important but meeting these targets without specific and integrative approaches depending on the source and type of emissions may result in failure. These approaches should also focus on the social costs of emissions, which raises the need for a new concept of integrating net-zero emissions and social costs.

Efficient and compact source of tuneable ultrafast deep ultraviolet laser pulses at 50 kHz repetition rate.

Deep ultraviolet (DUV) laser pulses with tuneable wavelength and very short duration are a key enabling technology for next-generation technology and ultrafast science. Their generation has been the subject of extensive experimental effort, but no technique demonstrated thus far has been able to meet all requirements in one light source. Here we demonstrate a bright, efficient, and compact source of tuneable DUV ultrafast laser pulses based on resonant dispersive wave emission in hollow capillary fiber. In a total footprint of only 120cm×75cm, including the ytterbium-based drive laser, we generate pulses between 208nm and 363nm at 50kHz repetition rate with a total efficiency of up to 3.6%. Down-scaling of the DUV generation reduces the required energy sufficiently to enable the generation of two-color few-femtosecond DUV pulses.

Hydrogen production, storage and transport for renewable energy and chemicals: An environmental footprint assessment

Hydrogen applications range from an energy carrier to a feedstock producing bulk and other chemicals and as an essential reactant in various industrial applications. However, the sustainability of hydrogen production, storage and transport are neither unquestionable nor equal. Hydrogen is produced from natural gas, biogas, aluminium, acid gas, biomass, electrolytic water splitting and others; a total of eleven sources were investigated in this work. The environmental impact of hydrogen production, storage and transport is evaluated in terms of greenhouse gas and energy footprints, acidification, eutrophication, human toxicity potential, and eco-cost. Different electricity mixes and energy footprint accounting approaches, supported by sensitivity analysis, are conducted for a comprehensive overview. H2 produced from acid gas is identified as the production route with the highest eco-benefit (−41,188 €/t H2), while the biomass gasification method incurred the highest eco-cost (11,259 €/t H2). The water electrolysis method shows a net positive energy footprint (60.32 GJ/t H2), suggesting that more energy is used than produced. Considering the operating footprint of storage, and transportation, gaseous hydrogen transported via a pipeline is a better alternative from an environmental point of view, and with a lower energy footprint (38 %–85%) than the other options. Storage and transport (without construction) could have accounted for around 35.5% of the total GHG footprint of a hydrogen value chain (production, storage, transportation and losses) if liquefied and transported via road transport instead of a pipeline. The identified results propose which technologies are less burdensome to the environment.

Quantifying universities’ direct and indirect carbon emissions – the case of Delft University of Technology

PurposeThe purpose of this paper is to present a comprehensive analysis of the carbon footprint of the Delft University of Technology (TU Delft), including direct and indirect emissions from utilities, logistics and purchases, as well as a discussion about the commonly used method. Emissions are presented in three scopes (scope 1 reports direct process emissions, scope 2 reports emissions from purchased energy and scope 3 reports indirect emissions from the value chain) to identify carbon emission hotspots within the university’s operations.Design/methodology/approachThe carbon footprint was calculated using physical and monetary activity data, applying a process and economic input-output analysis.FindingsTU Delft’s total carbon footprint in 2018 is calculated at 106 ktCO2eq. About 80% are indirect (scope 3) emissions, which is in line with other studies. Emissions from Real estate and construction, Natural gas, Equipment, ICT and Facility services accounted for about 64% of the total footprint, whereas Electricity, Water and waste-related carbon emissions were negligible. These findings highlight the need to reduce universities’ supply chain emissions.Originality/valueA better understanding of carbon footprint hotspots can facilitate strategies to reduce emissions and finally achieve carbon neutrality. In contrast to other work, it is argued that using economic input-output models to calculate universities’ carbon footprints is a questionable practice, as they can provide only an initial estimation. Therefore, the development of better-suited methods is called for.

Energy and environmental performance of photovoltaic cooling using phase change materials under the Mediterranean climate

The energy and environmental performance of photovoltaic (PV) panel cooling, when using phase change materials (PCMs), was examined. Actual, long-term field data were collected from a PV and a PV-PCM system, both operating under Mediterranean conditions (Greece). The energy analysis revealed that even though cooling increases (9.4%) the panel's energy output, PCM cooling is associated with a high initial energy investment, leading to low energy-return-on-investment values (1.79) compared to PV (4.94). High energy payback times were observed for the PV-PCM (⁓14 years) compared to the PV system (⁓5 years). Furthermore, the life cycle assessment methodology revealed that PCM cooling increases PV's total environmental footprint by 21.9%. However, in the Greek context, the additional electricity attributed to PV cooling leads to significant environmental gains through fossil-fuel-dependent electricity substitution. Cooling can also decrease the rate of cell degradation and prolong PV useful life, leading to additional environmental gains. Due to PCM's initial high energy investment, other cooling technologies should also be examined since, apart from improving electricity output and stability, cooling can also reduce PV's impact on land use, increase the power sector's decarbonization, and address global warming's impact on PV performance by reducing temperature fluctuations and extremes on the panel's surface.

Social outcomes of energy use in the United Kingdom: Household energy footprints and their links to well-being

How energy relates to human need satisfaction, for whom, and with what wellbeing outcomes has remained under-researched. We address this gap by investigating the relationship between household energy footprint and well-being in the UK. Our results indicate that car and air transportation contributed the most to the total energy footprint of high-income and high-energy users. We find significant inequalities in the distribution of energy use and that the top energy users with high well-being are driving excess energy use. A more detailed analysis reveals that individuals with protected characteristics are particularly vulnerable to energy poverty and that their contribution to overall energy demand is negligible. We find that focusing on well-being steers the attention towards questions of sufficiency, overconsumption as well as the context within which we satisfy needs. Tackling the issues of energy poverty and inequalities are important for lowering energy demand and need to be addressed as a matter of climate justice.

The environmental impact of the Dutch health-care sector beyond climate change: an input–output analysis

Studies suggest that the Dutch health-care sector is responsible for 4-8% of the national carbon footprint, but the environmental footprint of this sector beyond climate change is not well understood. Therefore, we aimed to estimate the environmental footprint of the Dutch health-care sector for a range of environmental impact categories. In this input-output analysis, we used Exiobase (version 3), which contains data on global trade flows and their associated environmental impact, in combination with health-care expenditure data from Statistics Netherlands. We covered the impact categories: climate change, blue water consumption, abiotic material extraction, land use, and total waste generation. The calculated sectoral footprint was the sum of all impacts associated with the operational phase (direct impact) and impacts occurring in the value chain of purchased goods and services (indirect impact) given an expenditure vector. The expenditure vector was the sum of three elements of health-care expenditure: health-care services; pharmaceuticals and chemical products; and medical appliances. We calculated the impact share of health care on the total Dutch consumption footprint. We evaluated the contribution to the impact categories from the categories that composed the expenditure vector. We did a hotspot analysis in which the indirect impact was split according to where (sector, geography, or both) the impact physically occurred. These top-down results were complemented with bottom-up data on emissions from pressurised metered-dose inhalers, anaesthetic gases, and private travel. The health-care sector's share of the national footprint was highest for material extraction (13·0%), followed by blue water consumption (7·5%), climate change (7·3%), land use (7·2%), and waste generation (4·2%). Pharmaceuticals and other chemical products were the biggest contributors to all impacts. The sectors contributing to climate change were more evenly distributed than the sectors contributing to the other impact categories. The mining sector mostly contributed to material extraction and the agricultural sector contributed largely to blue water consumption and land use. The mining sector and the agricultural sector were the main contributors to waste generation. Climate change occurred mainly in the Netherlands, whereas the other impacts mainly occurred abroad. The Dutch health-care sector contributes to a broad set of environmental impact categories beyond climate change. Our results will help stakeholders involved in the health-care sector to pinpoint topics that need to be prioritised and to prevent trade-offs by addressing multiple environmental issues simultaneously. Dutch Ministry of Health, Welfare and Sport.

Photonic Crystal Based All-Optical Switch Using a Ring Resonator and Kerr Effect

ABSTRACT This paper proposes an all-optical switch using Kerr-type nonlinearity based on a photonic crystal ring resonator (PCRR). For the first time, the bar state and cross-state operation with 2 × 2 elements of an optical switch is implemented using a nonlinear ring resonator. Chalcogenide glass rods are used in the air background to simulate the proposed structure. The operating wavelength for this structure is calculated to be 1551 nm using the finite element method. The functional parameters such as the extinction ratio, response time, bit rate, crosstalk, and insertion loss values are studied using the finite-difference time-domain (FDTD) method. The presented structure design has a fast data rate of 0.46 Tbps, a low crosstalk value of −17.14 dB, and a fast response time of 2.16 ps. The proposed optical switch has a total footprint of about 398.56 μm2. The device’s performance makes it suitable for switching applications and integration in all-optical circuits.

A Memory Efficient FPGA Implementation of Offset-Free Explicit Model Predictive Controller

In the explicit model predictive control (EMPC), memory increases exponentially with the number of states, inputs, constraints, and prediction horizons; this often limits its applicability to large systems. In this article, we present a novel memory reduction technique for the lightweight EMPC using a novel posit number format implemented on a field-programmable gate array (FPGA), aiming to reduce the memory footprints and power utilization of the EMPC. We developed a fully automatic framework for the design of fast embedded EMPC on FPGAs using posit arithmetic and logical unit (ALU). The proposed technique is based on encoding all data (i.e., the critical regions and the feedback laws) as posit numbers, which can be viewed as a more memory-efficient alternative to the IEEE 754 floating-point standard. The performance and efficiency of the developed posit-based offset-free EMPC are demonstrated on the anesthesia control problem. We show the results of hardware-in-the-loop co-simulation with the detailed analysis of the resource utilization, power utilization, clock achieved, and the memory footprints comparison between IEEE 754 floating-point and posit formats. By doing so, we illustrate that the total memory footprints can be reduced by 50%–75% with achieving low power utilization as compared to floating-point numbers without sacrificing the control performances. The proposed technique can be applied on top of other existing complexity reduction techniques used in EMPC as well as for the online optimization methods.