Existing Modeling Tools Research Articles

SketchMetaFace: A Learning-Based Sketching Interface for High-Fidelity 3D Character Face Modeling.

Modeling 3D avatars benefits various application scenarios such as AR/VR, gaming, and filming. Character faces contribute significant diversity and vividity as a vital component of avatars. However, building 3D character face models usually requires a heavy workload with commercial tools, even for experienced artists. Various existing sketch-based tools fail to support amateurs in modeling diverse facial shapes and rich geometric details. In this article, we present SketchMetaFace - a sketching system targeting amateur users to model high-fidelity 3D faces in minutes. We carefully design both the user interface and the underlying algorithm. First, curvature-aware strokes are adopted to better support the controllability of carving facial details. Second, considering the key problem of mapping a 2D sketch map to a 3D model, we develop a novel learning-based method termed "Implicit and Depth Guided Mesh Modeling" (IDGMM). It fuses the advantages of mesh, implicit, and depth representations to achieve high-quality results with high efficiency. In addition, to further support usability, we present a coarse-to-fine 2D sketching interface design and a data-driven stroke suggestion tool. User studies demonstrate the superiority of our system over existing modeling tools in terms of the ease to use and visual quality of results. Experimental analyses also show that IDGMM reaches a better trade-off between accuracy and efficiency.

Requirements for modelling tools for teaching

Modelling is an important activity in software development and it is essential that students learn the relevant skills. Modelling relies on dedicated tools and these can be complex to install, configure, and use—distracting students from learning key modelling concepts and creating accidental complexity for teachers. To address these challenges, we believe that modelling tools specifically aimed at use in teaching are required. Based on discussions at a working session organised at MODELS 2023 and the results from an internationally shared questionnaire, we report on requirements for such modelling tools for teaching. We also present examples of existing modelling tools for teaching and how they address some of the requirements identified.

A REVIEW OF ANIMAL MODELS FOR BONE FRACTURE NONUNION AND THEIR ROLE IN STUDYING BIOLOGICAL THERAPY EFFICACY

The bone healing impairment, such as non-union fractures after injuries of long bones, lead to loss of working capacity and result in significant financial costs, which emphasizes the socioeconomic significance of the problem. However, it is not known which method of modeling the non-union bone fractures is more optimal for further research into the effectiveness of biological therapy aimed at treating bone healing impairment. For a detailed study of methods of non-union fracture treatment of, it is necessary to determine the developed animal models. The objective was to analyze the existing animal models of fracture nonunion in long bones in vivo and to consider the possibility of their further use to evaluate the effectiveness of the use of modern biotechnologies for the in the management of fracture nonunion. It was found that the majority of developed animal models of atrophic long bone non-union were created using small animals, namely rats, mice, and rabbits. A more common method of modeling bone non-union is performing an osteotomy with the formation of a defect of different widths between the bone fragments and subsequent removal of the periosteum proximal and distal to the osteotomy site; damage to the endosteum or removal of bone marrow. Also, in such animal models, researchers use a silicone spacer, a polysulfone plate, or a latex-silicone foil to physically prevent fracture union. In these animal models, studies using mesenchymal stromal cells, platelet-rich plasma or bone morphogenetic protein-2 (BMP-2) have already been conducted for the management of non-union bone fractures. At the same time, the clinical results of the application of various biological therapies are ambiguous, which determines the conduct of further experimental studies, in particular, in vivo. However, there are disagreements about which in vivo modeling methods give a reproducible result and prevent bone union, which determines the need for further analysis of existing modeling tools for conducting research in this direction.

Nuclear Magnetic Resonance Chemical Shift as a Probe for Single‐Molecule Charge Transport

AbstractExisting modelling tools, developed to aid the design of efficient molecular wires and to better understand their charge‐transport behaviour and mechanism, have limitations in accuracy and computational cost. Further research is required to develop faster and more precise methods that can yield information on how charge transport properties are impacted by changes in the chemical structure of a molecular wire. In this study, we report a clear semilogarithmic correlation between charge transport efficiency and nuclear magnetic resonance chemical shifts in multiple series of molecular wires, also accounting for the presence of chemical substituents. The NMR data was used to inform a simple tight‐binding model that accurately captures the experimental single‐molecule conductance values, especially useful in this case as more sophisticated density functional theory calculations fail due to inherent limitations. Our study demonstrates the potential of NMR spectroscopy as a valuable tool for characterising, rationalising, and gaining additional insights on the charge transport properties of single‐molecule junctions.

Nuclear Magnetic Resonance Chemical Shift as a Probe for Single-Molecule Charge Transport.

Existing modelling tools, developed to aid the design of efficient molecular wires and to better understand their charge-transport behaviour and mechanism, have limitations in accuracy and computational cost. Further research is required to develop faster and more precise methods that can yield information on how charge transport properties are impacted by changes in the chemical structure of a molecular wire. In this study, we report a clear semilogarithmic correlation between charge transport efficiency and nuclear magnetic resonance chemical shifts in multiple series of molecular wires, also accounting for the presence of chemical substituents. The NMR data was used to inform a simple tight-binding model that accurately captures the experimental single-molecule conductance values, especially useful in this case as more sophisticated density functional theory calculations fail due to inherent limitations. Our study demonstrates the potential of NMR spectroscopy as a valuable tool for characterising, rationalising, and gaining additional insights on the charge transport properties of single-molecule junctions.

Application of watershed-scale habitat modeling and decision-support tools for reservoir reoperations in coastal northern California

Water managers must often balance the needs of both aquatic habitat and human water supply. However, they frequently only have the tools to manage water delivery alone. Existing modeling tools for habitat have gaps in providing detailed biological estimates at a watershed scale and in simulating water supply operations and habitat suitability simultaneously. A new modeling platform and calculation framework, Aquatic Habitat Assessment, was applied in a case study to quantify habitat suitability and fish passage at a watershed scale for local species of Chinook salmon (Oncorhynchus tshawytscha) and steelhead trout (Oncorhynchus mykiss). Aquatic Habitat Assessment was coupled with a suite of tools, including HEC-RAS used for hydraulics, WEAP for water allocations, and Tableau for visualization. The tools ensemble was used to simulate the operations of a water utility system near San Francisco Bay in California to evaluate the effects of reservoir reoperations on both human water supply and aquatic habitat. The suite of tools was successful in bringing a range of conflicting parties to coalesce around a common solution for reservoir operations. Two sets of alternative reservoir operation schemes were developed, which largely involve higher winter and lower summer releases, aligning more closely with natural Mediterranean patterns and functional flows connected to the biological needs of local aquatic species. Results quantify tradeoffs across reservoir operation schemes, with modeled fish passage habitat suitability increased under the reservoir reoperations, but human water supply delivery decreased. The modeled spawning, incubation, and rearing habitat suitability increased during the winter release period under reoperations, but decreased during the summer release period.

Matrix representation of lateral soil movements: scaling and calibrating CE-DYNAM (v2) at a continental level

Abstract. Promoting sustainable soil management is a possible option for achieving net-zero greenhouse gas emissions in the future. Several efforts in this area exist, and the application of spatially explicit models to anticipate the effect of possible actions on soils at a regional scale is widespread. Currently, models can simulate the impacts of changes on land cover, land management, and the climate on the soil carbon stocks. However, existing modeling tools do not incorporate the lateral transport and deposition of soil material, carbon, and nutrients caused by soil erosion. The absence of these fluxes may lead to an oversimplified representation of the processes, which hinders, for example, a further understanding of how erosion has been affecting the soil carbon pools and nutrients through time. The sediment transport during deposition and the sediment loss to rivers create dependence among the simulation units, forming a cumulative effect through the territory. If, on the one hand, such a characteristic implies that calculations must be made for large geographic areas corresponding to hydrological units, on the other hand, it also can make models computationally expensive, given that erosion and redeposition processes must be modeled at high resolution and over long timescales. In this sense, the present work has a three-fold objective. First, we provide the development details to represent in matrix form a spatially explicit process-based model coupling sediment, carbon, and erosion, transport, and deposition (ETD) processes of soil material in hillslopes and valley bottoms (i.e., the CE-DYNAM model). Second, we illustrate how the model can be calibrated and validated for Europe, where high-resolution datasets of the factors affecting erosion are available. Third, we presented the results for a depositional site, which is highly affected by incoming lateral fluxes from upstream lands. Our results showed that the benefits brought by the matrix approach to CE-DYNAM enabled the before-precluded possibility of applying it on a continental scale. The calibration and validation procedures indicated (i) a close match between the erosion rates calculated and previous works in the literature at local and national scales, (ii) the physical consistency of the parameters obtained from the data, and (iii) the capacity of the model in predicting sediment discharge to rivers in locations observed and unobserved during its calibration (model efficiency (ME) =0.603, R2=0.666; and ME =0.152, R2=0.438, respectively). The prediction of the carbon dynamics on a depositional site illustrated the model's ability to simulate the nonlinear impact of ETD fluxes on the carbon cycle. We expect that our work advances ETD models' description and facilitates their reproduction and incorporation in land surface models such as ORCHIDEE. We also hope that the patterns obtained in this work can guide future ETD models at a European scale.

PTSNet: A Parallel Transient Simulator for Water Transport Networks based on vectorization and distributed computing

Modeling transient flow in water transport networks (WTNs) is characterized by hyperbolic partial differential equations. Existing commercial and open-source software for transient modeling in WTNs have limitations, such as lack of scalability and compatibility with high-performance computers, difficulty to systematically execute simulations and analyze results. This work proposes a novel open-source Python package that relies on vectorization and distributed computing to overcome the limitations of existing software. The proposed library, the Parallel Transient Simulator for Water Networks (PTSNet), surpasses in computational performance existing modeling tools and incorporates novel analytics functionalities. PTSNet has been tested on WTNs composed of tens, hundreds, and thousands of hydraulic elements using a personal and a supercomputer, running from tens to hundreds of processors. We show through rigorous analyses that PTSNet is scalable, accurate, and significantly speeds up simulations with sufficiently dense numerical grids.

Are Existing Modeling Tools Useful to Evaluate Outcomes in Mangrove Restoration and Rehabilitation Projects? A Minireview

Ecosystem modeling is a critical process for understanding complex systems at spatiotemporal scales needed to conserve, manage, and restore ecosystem services (ESs). Although mangrove wetlands are sources of ESs worth billions of dollars, there is a lack of modeling tools. This is reflected in our lack of understanding of mangroves’ functional and structural attributes. Here, we discuss the “state of the art” of mangrove models used in the planning and monitoring of R/R projects during the last 30 years. The main objectives were to characterize the most frequent modeling approach, their spatiotemporal resolution, and their current utility/application in management decisions. We identified 281 studies in six broad model categories: conceptual, agent-based (ABM), process-based (PBM), spatial, statistical, and socioeconomic/management (ScoEco). The most widely used models are spatial and statistical, followed by PBM, ScoEco, and conceptual categories, while the ABMs were the least frequently used. Yet, the application of mangrove models in R/R projects since the early 1990s has been extremely limited, especially in the mechanistic model category. We discuss several approaches to help advance model development and applications, including the targeted allocation of potential revenue from global carbon markets to R/R projects using a multi-model and integrated approach.

A forage brassica simulation model using APSIM: Model calibration and validation across multiple environments

Forage brassicas have historically been used in high rainfall/irrigated temperate livestock systems, but there is increasing interest in diverse forage brassicas in drier mixed crop-livestock farming systems. Computer-based modelling is an important decision support tool used in agriculture to explore the adaptability of crops to different climates and agronomic management practices, but existing modelling tools for forage brassicas are limited to temperate environments. We parameterised the APSIM (Agricultural Production Systems Simulator) model for four forage brassica genotypes, including three diverse forage rape cultivars and a raphanobrassica. The model was calibrated using two experiments with repeated measures of biomass components, nutritive value, and leaf and canopy development. We then tested the model extensively using data from a diverse set of environments within Australian and New Zealand (23 sites across four agro-climatic zones). Model predictions of biomass were good for all the genotypes (NSE > 0.60, Nash-Sutcliffe efficiency; RMSE ~1.5 t DM/ha, root mean square error). Predictions of metabolisable energy yield were satisfactory for all genotypes (NSE 0.43–0.73; RMSE ~17.8 GJ ME/ha) but forage dry matter digestibility (DMD) were poorly predicted due to the small variation in observed data. Our robust and widely tested model can be confidently used to predict forage productivity of common and new forage brassicas across a wide range of production environments and agronomic management practices. This model will enable future work to develop a better understanding of the potential value of these important forage crops for livestock production systems.

Bubble coalescence and break-up in confined oscillating two-phase flows under microgravity conditions

Passive two-phase heat transfer systems, such as pulsating heat pipes, are a promising thermal management solution for the rapidly growing space sector. The strong coupling between thermal and hydraulic phenomena complicated the development of reliable off-the-shelf components. This was due to the difficulties in establishing and maintaining the desired slug-plug flow pattern in a wider region sufficiently far from the annular flow, which can lead to evaporator dry-out. In this work, inertial effects on the flow pattern are investigated under adiabatic conditions to define what limits the operability range of a device. The fluid motion characteristics of pulsating heat pipes have been mechanically induced to observe conditions that lead to the break-up or coalescence of bubbles. The authors were granted access to the ESA drop tower microgravity platform to explore surface tension dominant flows and higher hydraulic diameters compared to the ground capillary diameters. A range of fluids (FC-72 and ethanol) and diameters (2.5 mm to 8 mm) has been explored, along with combinations of oscillating fluid flow, analysing high-speed images and estimating velocity and acceleration. Both the Reynolds number, in combination with the modified Bond number, have been investigated, plotting the operating points on a flow map, showing a very clear limit between break-up and coalescence when the velocity and acceleration signs are considered. This new conceptual flow map can be used to further improve existing modelling tools for pulsating heat pipes operating under reduced gravity. Furthermore, images demonstrating the break-up and coalescence may be aid to CFD scientists in verifying their results.

FN-CACTI: Advanced CACTI for FinFET and NC-FinFET Technologies

Cache memories are an indispensable component of many processor-based systems and contribute significantly to the overall area, power consumption, and delay. This leads to an important role played by modeling tools for estimating the area, power consumption, and access time of cache memories. However, existing modeling tools such as CACTI and its various extensions have been primarily designed using data from various projections. For the first time, we propose an entire flow for obtaining/calibrating the transistor characteristics from a commercial technology and use these characteristics within CACTI. We also improve the modeling approach to make them more fine-grained and follow recent manufacturing trends suitable for FinFET technology. Further, for the first time, we extend CACTI to support negative capacitance fin field effect transistor (NC-FinFET), an emerging technology depicting negative capacitance whose current and capacitive characteristics are very different compared to those of the FinFET. We use the proposed tool (FN-CACTI) to identify NC-FinFET-based caches to be significantly more energy-efficient than corresponding FinFET-based caches. We also study an application of FN-CACTI to determine optimal voltages corresponding to the lowest energy consumption for NC-FinFET and FinFET-based caches of various sizes.

Sources of Variability and Uncertainty in Food-Energy-Water Nexus Systems

Highlights Accounting for variability and uncertainty empowers stakeholders to make better-informed decisions. Considering spatial and temporal sources of variability contributes to more robust modeling systems. Stochastic methods that factor in uncertainty contribute to a better understanding of the FEW nexus systems. A robust modeling system will contribute to the design of resilient FEW nexus systems. Abstract. A nexus approach contributes to the strategic allocation of resources to secure food, energy, and water for the world population. Integrated models considering the complex interactions across food, energy, and water (FEW) enhance decision-making and strategic planning towards resilience. However, a significant number of the existing integrated models leave unaddressed the inherent variability and uncertainty present in the FEW sectors. Here, we review the importance of characterizing variability over spatial and temporal scales and the importance of decreasing the uncertainty present within a FEW nexus systems. The review also discusses existing modeling tools that address variability and uncertainty on single and paired elements of the FEW nexus systems, as well as integrated tools that address the sources of variability and uncertainty across the nexus. Finally, the review highlights the opportunity to address the limitations of existing models through multidisciplinary approaches and the potential to integrate publicly available models, as has already been the case for single and coupled elements of the FEW nexus. Addressing variability and uncertainty would improve the robustness of a FEW systems modeling and would provide stakeholders with the capacity to make better-informed decisions. Keywords: Climate variability, Food-water-energy nexus, Modeling, Spatial variability, Temporal variability, Uncertainty.

Prediction of Potentially Suitable Distributions of Codonopsis pilosula in China Based on an Optimized MaxEnt Model

Species distribution models are widely used in conservation biology and invasive biology. MaxEnt models are the most widely used models among the existing modeling tools. In the MaxEnt modeling process, the default parameters are used most often to build the model. However, these models tend to be overfit. Aiming at this problem, this study uses an optimized MaxEnt model to analyze the impact of past, present and future climate on the distributions of Codonopsis pilosula, an economic species, to provide a theoretical basis for its introduction and cultivation. Based on 264 distribution records and eight environmental variables, the potential distribution areas of C. pilosula in the last interglacial, middle Holocene and current periods and 2050 and 2070 were simulated. Combined with the percentage contribution, permutation importance, and jackknife test, the environmental factors affecting the suitable distribution area of this species were discussed. The results show that the parameters of the optimal model are: the regularization multiplier is 1.5, and the feature combination is LQHP (linear, quadratic, hinge, product). The main temperature factors affecting the distribution of C. pilosula are the annual mean temperature, mean diurnal range, and isothermality. The main precipitation factors are the precipitation seasonality, precipitation in the wettest quarter, and precipitation in the driest quarter, among which the annual average temperature contributes the most to the distribution area of this species. With climate warming, the suitable area of C. pilosula exhibits a northward expansion trend. It is estimated that in 2070, the suitable area of this species will expand to its maximum, reaching 2.5108 million square kilometers. The highly suitable areas of C. pilosula are mainly in Sichuan, Gansu, Shaanxi, Shanxi, and Henan Provinces. Our findings can be used to provide theoretical support related to avoiding the blind introduction of C. pilosula.

Modelling of Nutrient Pollution Dynamics in River Basins: A Review with a Perspective of a Distributed Modelling Approach

Nutrient pollution is one of the major issues in water resources management, which has drawn significant investments into the development of many modelling tools to solve pollution problems worldwide. However, the situation remains unchanged, even likely to be exacerbated due to population growth and climate change. Effective measures to alleviate the issues are essential, dependent upon existing modelling tools’ capacities. More complex models have been developed with technological advancement, though applications are mainly limited to academic reach. Hence, there is a need for a paradigm shift in policymaking that looks for a reliable modelling approach. This paper aims to assess the capacity of existing modelling tools in the context of process-based modelling and provide a future direction in research. The article has categorically divided models into plot scale to basin-wide applications for evaluation and discussed the pros and cons of conceptual and process-based modelling. The potential benefits of distributed modelling approach have been elaborated with highlights of a newly developed distributed model and its application in catchments in Japan and Australia. The distributed model is more adequate for predicting the realistic details of pollution problems in a changing environment. Future research needs to focus on more process-based modelling.

Carsharing in the Czech Republic: Understanding why users chose this mode of travel for different purposes

Carsharing is a relatively new and growing mobility service in many cities. Although there are numerous carsharing initiatives in operation around the world, it is still not clear how they will affect overall travel behavior. Understanding the effects of carsharing when combined with other existing travel modes is an important prerequisite for decision-makers for them to be able to positively utilise the benefits of carsharing services. Such new mobility services need to be incorporated into existing modelling tools to reliably evaluate the impact of specific measures and policies.The presented study provides an insight into one aspect of such models: the use of carsharing for various trip purposes by users with different socio-demographic characteristics and attitudes. We identify variables that should be used for computing the utility function for users with different backgrounds, perceptions, and preferences.In this study, existing users of a carsharing company operating in various Czech cities participated in a survey and their responses were paired with records of their real carsharing usage patterns. To reduce the number of variables, principal component analysis was used, mainly with attitudinal and perception questions. The principal components based on survey respondents’ attitudes towards carsharing and socio-demographic and other variables were used in logistic regression to identify parameters that most significantly influence various purposes for trips.The results confirm the hypothesis that trip purposes differ significantly among carsharing users and need to be incorporated into macroscopic carsharing usage models. These findings can assist municipality representatives and transport companies in considering carsharing as a valid and sustainable travel mode in traffic models and studies.

CHECKSUM: tracking changes and measuring contributions in cooperative systems modeling

Models are often used to represent various types of systems. This is especially true for software systems, where cooperating teams create models using a modeling language (e.g., UML). In cooperative modeling scenarios, it is useful to identify contributions and changes performed by individuals and teams. This paper presents a technique called CHECKSUM, which monitors the cooperative work done on models and maintains an immutable changelog. CHECKSUM uses its changelog to measure contributions based on points, time, and quality, and to enable the auditing of a model’s change-history. This paper also presents GEneric Meta-Model (GEMM). The latter unifies the underlying representation of different types of models that follow varying visualization patterns including box and line, container, and interleaving. GEMM enables CHECKSUM to support an extensible variety of model types. We developed a prototype tool that realizes CHECKSUM’s concepts and integrates it into two existing modeling tools. We conducted two studies to evaluate CHECKSUM from two perspectives: technical and user. The studies yielded positive results concerning various qualities including integrability into existing tools, effectiveness, efficiency, usability, and usefulness.

Extending Model-Based Systems Engineering into Integrated Platform Designed for Civil Aircraft Develop

With the continuous development and application of modeling technology, civil aircraft designers urgently need to apply model-based systems engineering (MBSE) theory and methods into the field of civil aircraft development. However, the existing modeling tools, which combined with MBSE methodologies, only focus on one particular area, such as requirement modeling, functional modeling and design synthesis. This kind of low coupling design system makes it difficult to link the upstream and downstream designers in the early stage of system development. This paper introduces the MBSE development process of civil aircraft and then establishes an integrated platform composed of six work stations for civil aircraft development based on this process. Commercially available modeling tools, such as IBM Rational DOORS and enterprise architect (EA), are conducted in the platform. The development of flight control system is taken as an example to test the feasibility and efficiency of our integrated platform in logic layer. This platform can complete the activities of aircraft life cycle function analysis, requirement and model management. The loose coupling between the modules and the high cohesive nature allows different system engineers to maintain their design independence and consistency at different stages of development.

Tools for logging and analyzing goal dependency modeling

Modeling goal dependencies among people and systems contributes to exploring the systems valuable to the people. Therefore, guiding such modeling processes is useful for the system development. Because there is no predefined process model of good goal dependency modeling, we have to clarify the characteristics of actual modeling processes for a start. In this paper, we introduce the tools for logging and analyzing goal dependency modeling. We also report a case study to use the tools so as to find common characteristics of the modeling processes. We expect such tools help us to find how to guide a modeling process. The logging tool is developed by expanding an existing modeling tool called astah. Each developer can thus easily record the logs with his/her familiar modeling tool. The analyzing tools finally visualize each modeling process in several ways by using Graphvis. We can observe the development process, and analyze the common characteristics with the help of these tools. Although we cannot find the unknown and unique characteristics, we can confirm some reasonable characteristics. For example, the ratio of transitions between goals and other elements is larger than the other ratio.

DSP: Schema Design for Non-Relational Applications

The way a database schema is designed has a high impact on its performance in relational databases, which are symmetric in nature. While the problem of schema optimization is even more significant for NoSQL (“Not only SQL”) databases, existing modeling tools for relational databases are inadequate for this asymmetric setting. As a result, NoSQL modelers rely on rules of thumb to model schemas that require a high level of competence. Several studies have been conducted to address this problem; however, they are either proprietary, symmetrical, relationally dependent or post-design assessment tools. In this study, a Dynamic Schema Proposition (DSP) model for NoSQL databases is proposed to handle the asymmetric nature of today’s data. This model aims to facilitate database design and improve its performance in relation to data availability. To achieve this, data modeling styles were aggregated and classified. Existing cardinality notations were empirically extended using synthetically generated queries. A binary integer formulation was used to guide the mapping of asymmetric entities from the application’s conceptual data model to a database schema. An experiment was conducted to evaluate the impact of the DSP model on NoSQL schema production and its performance. A profound improvement was observed in read/write query performance and schema production complexities. In this regard, DSP has significant potential to produce schemas that are capable of handling big data efficiently.