An integrative modeling framework to evaluate the productivity and sustainability of biofuel crop production systems

The potential expansion of biofuel production raises food, energy, and environmental challenges that require careful assessment of the impact of biofuel production on greenhouse gas (GHG) emissions, soil erosion, nutrient loading, and water quality. In this study, we describe a spatially explicit integrative modeling framework (SEIMF) to understand and quantify the environmental impacts of different biomass cropping systems. This SEIMF consists of three major components: (1) a geographic information system (GIS)‐based data analysis system to define spatial modeling units with resolution of 56 m to address spatial variability, (2) the biophysical and biogeochemical model Environmental Policy Integrated Climate (EPIC) applied in a spatially‐explicit way to predict biomass yield, GHG emissions, and other environmental impacts of different biofuel crops production systems, and (3) an evolutionary multiobjective optimization algorithm for exploring the trade‐offs between biofuel energy production and unintended ecosystem‐service responses. Simple examples illustrate the major functions of the SEIMF when applied to a nine‐county Regional Intensive Modeling Area (RIMA) in SW Michigan to (1) simulate biofuel crop production, (2) compare impacts of management practices and local ecosystem settings, and (3) optimize the spatial configuration of different biofuel production systems by balancing energy production and other ecosystem‐service variables. Potential applications of the SEIMF to support life cycle analysis and provide information on biodiversity evaluation and marginal‐land identification are also discussed. The SEIMF developed in this study is expected to provide a useful tool for scientists and decision makers to understand sustainability issues associated with the production of biofuels at local, regional, and national scales.     

A statistical framework to evaluate virtual screening

Background  

Receiver operating characteristic (ROC) curve is widely used to evaluate virtual screening (VS) studies. However, the method fails to address the "early recognition" problem specific to VS. Although many other metrics, such as RIE, BEDROC, and pROC that emphasize "early recognition" have been proposed, there are no rigorous statistical guidelines for determining the thresholds and performing significance tests. Also no comparisons have been made between these metrics under a statistical framework to better understand their performances.     

A framework for quantifying environmental sustainability

Recent concepts of environmental sustainability have focused on narrative economic and societal aspects rather than quantitative ones. Many key sustainability indicators also lack a consistent definition of sustainability, have perspectives that are too short-term, and are unable to model the dynamics of complex environmental utilization which can then result in inappropriate projection of long-term sustainability and/or sustainability indication. Here I propose a generalized quantitative framework of environmental sustainability requiring that (1) environmental capacities and utilization rates are identified, (2) their complex temporal dynamics are quantitatively modeled or estimated (3) while also adjusting for uncertainties, and finally, (4) using one of three options, determining which cumulative utilization pathways can be sustained for a (usually well-defined) period of time. Using the example of wood volume and its growth as capacities and harvest as utilization, and the example of global greenhouse gas emissions as the utilization component and the capacity of the air to absorb these emissions, I demonstrate how the proposed framework can be applied in practice, how sustainability indicators could be developed, and also how they can inform policies and measures to ensure sustainability.     

A life cycle sustainability assessment (LCSA) of oxymethylene ether as a diesel additive produced from forest biomass

The International Journal of Life Cycle Assessment - Due to efforts to reduce dependence on limited fossil energy reserves and increasing GHG emissions related to fossil fuel extraction and use in...     

A general modeling framework for open wildlife populations based on the Polya tree prior

Wildlife monitoring for open populations can be performed using a number of different survey methods. Each survey method gives rise to a type of data and, in the last five decades, a large number of associated statistical models have been developed for analyzing these data. Although these models have been parameterized and fitted using different approaches, they have all been designed to either model the pattern with which individuals enter and/or exit the population, or to estimate the population size by accounting for the corresponding observation process, or both. However, existing approaches rely on a predefined model structure and complexity, either by assuming that parameters linked to the entry and exit pattern (EEP) are specific to sampling occasions, or by employing parametric curves to describe the EEP. Instead, we propose a novel Bayesian nonparametric framework for modeling EEPs based on the Polya tree (PT) prior for densities. Our Bayesian nonparametric approach avoids overfitting when inferring EEPs, while simultaneously allowing more flexibility than is possible using parametric curves. Finally, we introduce the replicate PT prior for defining classes of models for these data allowing us to impose constraints on the EEPs, when required. We demonstrate our new approach using capture–recapture, count, and ring-recovery data for two different case studies.     

A framework to evaluate whether to pool or separate behaviors in a multilayer network

A multilayer network approach combines different network layers,which are connected by interlayer edges,to create a single mathematical object.These networks can contain a variety of information types and represent different aspects of a system.However,the process for selecting which information to include is not always straightforward.Using data on 2 agonistic behaviors in a captive population of monk parakeets(Myiopsitta monachus),we developed a framework for investigating how pooling or splitting behaviors at the scale of dyadic relationships(between 2 individuals)affects individual-and group-level social properties.We designed 2 reference models to test whether randomizing the number of interactions across behavior types results in similar structural patterns as the observed data.Although the behaviors were correlated,the first reference model suggests that the 2 behaviors convey different information about some social properties and should therefore not be pooled.However,once we controlled for data sparsity,we found that the observed measures corresponded with those from the second reference model.Hence,our initial result may have been due to the unequal frequencies of each behavior.Overall,our findings support pooling the 2 behaviors.Awareness of how selected measurements can be affected by data properties is warranted,but nonetheless our framework disentangles these efforts and as a result can be used for myriad types of behaviors and questions.This framework will help researchers make informed and data-driven decisions about which behaviors to pool or separate,prior to using the data in subsequent multilayer network analyses.     

Application of LCSA to used cooking oil waste management

Purpose

Used cooking oil (UCO) is a domestic waste generated as the result of cooking and frying food with vegetable oil. The purpose of this study is to compare the sustainability of three domestic UCO collection systems: through schools (SCH), door-to-door (DTD), and through urban collection centres (UCC), to determine which systems should be promoted for the collection of UCO in cities in Mediterranean countries.

Methods

The present paper uses the recent life cycle sustainability assessment (LCSA) methodology. LCSA is the combination of life cycle assessment (LCA), life cycle costing, and social life cycle assessment (S-LCA).

Results and discussion

Of the three UCO collection systems compared, the results show that UCC presents the best values for sustainability assessment, followed by DTD and finally SCH system, although there are no substantial differences between DTD and SCH. UCC has the best environmental and economic performance but not for social component. DTD and SCH present suitable values for social performance but not for the environmental and economic components.

Conclusions

The environmental component improves when the collection points are near to citizens’ homes. Depending on the vehicle used in the collection process, the management costs and efficiency can improve. UCO collection systems that carry out different kind of waste (such as UCC) are more sustainable than those that collect only one type of waste. Regarding the methodology used in this paper, the sustainability assessment proposed is suitable for use in decision making to analyse processes, products or services, even so in social assessment an approach is needed to quantify the indicators. Defining units for sustainability quantification is a difficult task because not all social indicators are quantifiable and comparable; some need to be adapted, raising the subjectivity of the analysis. Research into S-LCA and LCSA is recent; more research is needed in order to improve the methodology.     

A framework for whole-cell mathematical modeling

The default framework for modeling biochemical processes is that of a constant-volume reactor operating under steady-state conditions. This is satisfactory for many applications, but not for modeling growth and division of cells. In this study, a whole-cell modeling framework is developed that assumes expanding volumes and a cell-division cycle. A spherical newborn cell is designed to grow in volume during the growth phase of the cycle. After 80% of the cycle period, the cell begins to divide by constricting about its equator, ultimately affording two spherical cells with total volume equal to twice that of the original. The cell is partitioned into two regions or volumes, namely the cytoplasm (Vcyt) and membrane (Vmem), with molecular components present in each. Both volumes change during the cell cycle; Vcyt changes in response to osmotic pressure changes as nutrients enter the cell from the environment, while Vmem changes in response to this osmotic pressure effect such that membrane thickness remains invariant. The two volumes change at different rates; in most cases, this imposes periodic or oscillatory behavior on all components within the cell. Since the framework itself rather than a particular set of reactions and components is responsible for this behavior, it should be possible to model various biochemical processes within it, affording stable periodic solutions without requiring that the biochemical process itself generates oscillations as an inherent feature. Given that these processes naturally occur in growing and dividing cells, it is reasonable to conclude that the dynamics of component concentrations will be more realistic than when modeled within constant-volume and/or steady-state frameworks. This approach is illustrated using a symbolic whole cell model.     

A PCA-based method for construction of composite sustainability indicators

Purpose

Sustainable manufacturing is practiced globally as a comprehensive strategy for improving the sustainability performance of the manufacturing industry. While sustainability is characterized into such three dimensions as economic, environmental, and social, currently, there is no quantitative method yet to measure the so-called ??sustainability?? in the manufacturing industry. The objective of this research is to develop a comprehensive and effective quantitative method to measure the overall sustainability performance of manufacturing companies.

Methods

In this paper, an integrated methodology is presented for the development of composite sustainability indicators based on principal component analysis (PCA). In developing this integrated approach, both industry and academia surveys are conducted to identify what sustainability indicators are favored by the sustainable manufacturing community. A unique index is then generated to measure the overall sustainability performance of industrial practices. The methodology can be used for benchmarking the overall sustainability performance of various manufacturing companies.

Results

A case study is conducted on a total of 11 global electronic manufacturing companies. The overall sustainability performance of these companies are measured, benchmarked, and ranked. The results showed that PCA is an effective approach for constructing composite sustainability indicators across environmental, economic, and social dimensions.

Conclusions

From this research, it is found that industry and academia have different views on the sustainability measurement, evidenced by different weights put on the same indicator in industry and academia. The case study demonstrated that the methodology presented in this paper is an effective tool for comprehensive measurement of sustainability performance of manufacturing companies. Strengths and weaknesses of each company can be identified. Then, the recommended improvements can be suggested based on the study of each of the individual indicators.     

Developing an indicator system for local governments to evaluate transport sustainability strategies

This study proposed an indicator system for measuring and monitoring transport sustainability at the county (or city) level. Twenty-one indicators were grouped into economy, environment, society, and energy aspects. A committee comprised of government officials from Taipei City and New Taipei City proposed transport solutions to improve the transport sustainability of the Taipei metropolitan area. Ten key indicators were selected to measure the sustainable transport strategies. This study applied Fuzzy Cognitive Maps (FCMs) and the Analytic Hierarchy Process (AHP) to construct the cause–effect relationships between these key indicators and to evaluate sustainable transport strategies. The evaluation results showed that the strategy of expanding mass rapid transit (MRT) lines was predicted to produce the most significant improvements; the strategy of integrating bus exclusive lanes would provide the least improvement; and the strategies of promoting cleaner vehicles and integrating Fu-Kang bus resources would perform similarly to each other in improving transport sustainability.     

A framework for evaluating sustainability indicators in the real estate industry

The growth in the use of sustainability indicators and ratings in the real estate industry has been accompanied by strong criticism of the most commonly used rating systems designed to evaluate the sustainability performance of real estate developments. Most of these criticisms focus on the content of the different rating systems. A systematic evaluation of the methodologies of sustainability ratings is lacking. This article builds a framework that can be used to evaluate the methodologies of sustainability ratings and applies the evaluation framework to five widely used sustainability ratings for homes and communities (BREAAM, CASBEE, Estidama, Green Star, LEED). The evaluation results highlight three major shortcomings in the rating systems that have been evaluated. First, the systems lack unambiguous definitions of sustainability. They give insufficient explanation of why certain components are included in the ratings and on what basis these components have been accorded their weights. Second, the rating systems put more emphasis on sustainable design than performance, especially for the ratings for communities. Finally, the ratings are generally not responsive to local conditions of a project. Each rating system has its particular strengths and weaknesses and no system is superior on all dimensions. The proposed evaluation framework can be applied to sustainability ratings in different industries and is adaptable depending on stakeholder requirements.     

A cell-based framework for modeling cardiac mechanics

Cardiomyocytes are the functional building blocks of the heart—yet most models developed to simulate cardiac mechanics do not represent the individual cells and their surrounding matrix. Instead, they work on a homogenized tissue level, assuming that cellular and subcellular structures and processes scale uniformly. Here we present a mathematical and numerical framework for exploring tissue-level cardiac mechanics on a microscale given an explicit three-dimensional geometrical representation of cells embedded in a matrix. We defined a mathematical model over such a geometry and parametrized our model using publicly available data from tissue stretching and shearing experiments. We then used the model to explore mechanical differences between the extracellular and the intracellular space. Through sensitivity analysis, we found the stiffness in the extracellular matrix to be most important for the intracellular stress values under contraction. Strain and stress values were observed to follow a normal-tangential pattern concentrated along the membrane, with substantial spatial variations both under contraction and stretching. We also examined how it scales to larger size simulations, considering multicellular domains. Our work extends existing continuum models, providing a new geometrical-based framework for exploring complex cell–cell and cell–matrix interactions.

     

基于建筑容量的城市建设用地碳汇量核算方法

城市建设中的矿物质材料开发利用活动不仅导致大量碳排放,也产生了碳吸收.以往建筑矿物质材料的碳吸收过程一直没有得到重视和科学量化.本研究采用遥感影像阴影高度反演技术,提取地块的建筑容量,识别建筑类型,以此为依据确定矿物材料用量及碳含量参数,采用热重分析法测定碳化率,基于以上步骤构建城市建筑碳汇量的核算方法,并选取沈阳市蒲河新来测试这一核算方法,同时进行不确定性分析.结果表明: 1996—2016年,沈阳市蒲河新城各类型建筑产生的碳汇总量依次为:居住建筑>公共服务建筑>其他类建筑>商业金融建筑>工业建筑;各类建筑用地的碳汇容积率依次为:商业金融建筑>居住建筑>公共服务建筑>其他类建筑>工业建筑.本研究构建的基于建筑容量提取的城市尺度的建筑碳汇量核算方法,可以快速准确地估算不同类型城市建设用地无机材料产生的碳汇量.在城市自然碳汇有限条件下,利用建筑碳汇增加城市碳汇量,能够为我国城市低碳发展提供新的思路.     

A framework for modeling of juxtacrine signaling systems

Juxtacrine signaling is intercellular communication, in which the receptor of the signal (typically a protein) as well as the ligand (also typically a protein, responsible for the activation of the receptor) are anchored in the plasma membranes, so that in this type of signaling the activation of the receptor depends on direct contact between the membranes of the cells involved. Juxtacrine signaling is present in many important cellular events of several organisms, especially in the development process. We propose a generic formal model (a modeling framework) for juxtacrine signaling systems that is a class of discrete dynamic systems. It possesses desirable characteristics in a good modeling framework, such as: a) structural similarity with biological models, b) capacity of operating in different scales of time, and c) capacity of explicitly treating both the events and molecular elements that occur in the membrane, and those that occur in the intracellular environment and that are involved in the juxtacrine signaling process. We have implemented this framework and used it to develop a new three-level discrete model for the neurogenic network and its participation in neuroblast segregation. This paper presents the details of this framework and its current status.     

A validated computational framework to evaluate the stiffness of 3D printed ankle foot orthoses

The purpose of this study was to create and validate a standardized framework for the evaluation of the ankle stiffness of two designs of 3D printed ankle foot orthoses (AFOs). The creation of four finite element (FE) models allowed patient-specific quantification of the stiffness and stress distribution over their specific range of motion during the second rocker of the gait. Validation was performed by comparing the model outputs with the results obtained from a dedicated experimental setup, which showed an overall good agreement with a maximum relative error of 10.38% in plantarflexion and 10.66% in dorsiflexion. The combination of advanced computer modelling algorithms and 3D printing techniques clearly shows potential to further improve the manufacturing process of AFOs.     

A framework for structured modeling of skeletal muscle

The aim of this study is to present a detailed continuum mechanics formulation, and the corresponding algorithms, to predict the deformation of skeletal muscle at different structural levels, starting from the muscle fiber level. The model is used to investigate force production and structural changes during isometric and dynamic contractions of the cat medial gastrocnemius. From a comparison with experimental data obtained in our own laboratories, we conclude that the model faithfully predicts all of the observations pertaining to force production, fascicle length and angle of pennation under various test conditions.     

Methodological framework to find links between life cycle sustainability assessment categories and the UN Sustainable Development Goals based on literature

Life cycle sustainability assessment (LCSA) can be used as a tool to understand how products and operating systems can meet the United Nations’ Sustainable Development Goals (SDGs). However, existing linkages between SDGs and LCSA are limited and an analysis of coverage in literature is needed. In this paper, we propose a generic methodological framework establishing connections between LCSA categories at micro-level and SDGs at macro-level based on derivation from the literature. The qualitative heuristic research method developed builds on keyword literature search, bibliometric analysis, mapping, and narrative literature review for connection rationales. By using qualitative assessment levels, an assessment of linkages between LCSA categories and SDGs reveal that “technology development,” “public commitment to sustainability issues,” “access to material resources,” and “education provided in the local community” have the highest number of reported relationships with SDGs. Twenty-two LCSA categories were found with no direct/indirect connection with any SDG; reasons include absence of life cycle thinking perspective in SDGs and lack of sustainability-based discussion for workers, consumers, and value chain actors' stakeholder groups. Despite these gaps, the results provide new insights for industries looking to measure the contribution of their product systems along their life cycle in the context of SDGs supporting them to some extent, to select LCSA categories with either highest number of identified relationships to SDGs or that contribute to prioritized list of SDGs. The approach provides a starting point to improve transparency and consistency of reporting of sustainability performance of product systems by connecting LCSA to the global agenda for sustainable development.     

基于生态系统服务供需的城市群生态安全格局构建框架

近年来,生态系统服务供需失调引发了一系列问题,诸如城市热岛、生态用地流失、环境污染、生物多样性减少等生态风险问题,已成为威胁生态安全、制约社会经济可持续发展的重要因素,因此维持生态系统服务供需平衡是生态安全健康发展的保障和关键。梳理了生态系统服务评价、生态安全格局构建的研究现状,指出了存在的不足,同时构建了基于生态系统服务的城市群生态安全格局基本框架,并提出了生态安全格局未来的研究重点:城市群区域和城市内部生态系统服务的多尺度综合评价、城市功能区的划分及对生态安全的胁迫作用、生态过程与生态系统服务与生态安全的耦合、基于生态系统服务流的生态安全格局构建、模拟和优化。通过耦合社会经济数据、卫星遥感数据、城市地图大数据,评价城市内部和外部不同尺度的生态系统服务,保障城市群生态系统服务流畅通传输,实现城市群生态安全格局评价和优化。     

An approach to LCSA: the case of concrete recycling

Purpose

The framework of life cycle sustainability analysis (LCSA) has been developed within the CALCAS project but the procedure on how an LCSA should be carried out is still far from standardized. The purpose of this article is to propose an approach to put the LCSA framework into practice. This approach is illustrated with an on-going case study on concrete recycling.

Methods

In the context of an EC-FP7 project on technology innovation for concrete recycling, five operational steps to implement the LCSA framework are proposed: (1) broad system definition, (2) making scenarios, (3) defining sub-questions for individual tools, (4) application of the tools and (5) interpreting the results in an LCSA framework. Focus has been put on the goal and scope definition (steps 1–3) to illustrate how to define a doable and meaningful LCSA. Steps 4–5 are not complete in the case study and are elaborated theoretically in this paper.

Results and discussion

The experience from the case study shows that the operational steps are especially useful at the stage of defining the goal and scope. Breaking down the sustainability questions into different scales and different aspects gives the possibility to define the sub-questions suitable to be assessed by the individual analytical tools (e.g., LCA, LCC, SLCA, MFA, etc.). The C2CA-LCSA shows a practical approach to model the life cycle impacts of the broad system is to start by modelling the technological system at the micro level and then scale it up with the realistic scenario settings that are generated with the knowledge gained from the MFA studies at the meso-level and from the policy/economic studies at the macro level. The combined application of LCA, LCC and SLCA at the project level shows not all the cost items and only one social impact indicator can be modelled in the process-based LCA structure. Thus it is important to address the left out information at the interpretation step.

Conclusions

Defining sub-questions on three different levels seems most useful to frame an LCSA study at the early stage of goal and scope definition. Although this study provides some useful steps for the operationlisation of the LCSA concept, it is clear that additional case studies are needed to move LCSA into a practical framework for the analysis of complex sustainability problems.