Exploitation Scenarios Research Articles

Building Information Modelling from Cadastral Plans and Application to an Italian Case Study Building Using Innovative Strategies

This paper explores the applicability of different methods to construct a Building information System Model (BIM) from 2D plans and, more specifically, cadastral plans. The explored procedures use three different approaches to build BIMs: one manual, one semi-automatic based on Rhinoceros/Grasshopper, and one based on Artificial Intelligence (AI). To analyse the performance of the three methods, the case study of a masonry building located in an Italian historic centre is used. The fastest is the AI-based method, although it has some limitations in automatic recognition of some objects. This latter aspect was further explored by analysing a very large dataset of cadastral plans. The results show good recognition of wall elements, but problems arise in the recognition of other elements, such as doors and windows. The manual method, on the other hand, allowed for the construction of a detailed model of the considered structure. However, the method requires strong user interaction and longer time frames than the AI-based method. The semi-automatic based method requires quite a lot of pre-processing but through an algorithm in Grasshopper a fast and detailed modelling of the structure is obtained. The paper also outlines future scenarios for the full exploitation of cadastral data.

Building Information Modelling from Cadastral Plans and Application to an Italian Case Study Building Using Innovative Strategies

This paper explores the applicability of different methods to construct a Building information System Model (BIM) from 2D plans and, more specifically, cadastral plans. The explored procedures use three different approaches to build BIMs: one manual, one semi-automatic based on Rhinoceros/Grasshopper, and one based on Artificial Intelligence (AI). To analyse the performance of the three methods, the case study of a masonry building located in an Italian historic centre is used. The fastest is the AI-based method, although it has some limitations in automatic recognition of some objects. This latter aspect was further explored by analysing a very large dataset of cadastral plans. The results show good recognition of wall elements, but problems arise in the recognition of other elements, such as doors and windows. The manual method, on the other hand, allowed for the construction of a detailed model of the considered structure. However, the method requires strong user interaction and longer time frames than the AI-based method. The semi-automatic based method requires quite a lot of pre-processing but through an algorithm in Grasshopper a fast and detailed modelling of the structure is obtained. The paper also outlines future scenarios for the full exploitation of cadastral data.

Simulation and prediction of land subsidence in Decheng District under the constraint of InSAR deformation information

Land subsidence, marked by a decline in surface elevation, poses a significant threat to urban infrastructure and safety. Accurate subsidence information and a reliable prediction model are crucial for prevention and control. In this study, we used persistent scatterer interferometric synthetic aperture radar (PS-InSAR) technology to obtain long-term land subsidence data and analyzed subsidence characteristics in Decheng District. By integrating hydrogeological and groundwater data, we developed a three-dimensional groundwater flow and one-dimensional compaction model through numerical simulation. Furthermore, the subsidence data monitored by PS-InSAR were used to further constrain and validate the model. The evolution trend of land subsidence under different groundwater exploitation scenarios was predicted and analyzed. The results showed that from May 2017 to December 2021, the cumulative maximum subsidence in Decheng District reached −173 mm. The subsidence area is mainly concentrated in the northern area, and its subsidence center is near Qiaoyuan Town. According to the Land Subsidence Prevention and Control Plan of Dezhou City, Shandong Province (2018–2025), we set up different groundwater mining scenarios with the goal that the rate of land subsidence in the key prevention and control area is less than 35 mm/yr in 2025.The Fluid-solid coupled model prediction analysis results indicated that a 30% reduction in groundwater exploitation is reasonable.

Development of a subsurface monitoring system for land subsidence hazard in the Bandung basin: a laboratory prototype

Abstract Land subsidence is a global environmental hazard posed by urban area worldwide, causing degradation in environmental quality and leads to further disasters such as increased flood risk, contamination risk, and infrastructure damages. Anthropogenic causes, such as groundwater extraction and building weight, cause high land subsidence rates. The behaviour of the subsurface under the influence of anthropogenic causes must be well understood to mitigate this problem. Conventional subsurface monitoring is robust and costly. In this case, we aim to first develop a versatile and low-cost subsurface monitoring prototype for land subsidence at a laboratory scale using a model box. Methods employed were constructing an experiment model box, developing the monitoring system, and trial experiments in the laboratory. The sensors are linear vertical displacement transducer, potentiometer, water level and pressure sensors. The monitoring system uses Arduino microcontroller to convert sensors inputs to desirable outputs and a logger to record the real-time data and transmit it to personal computer in the laboratory. Land subsidence in the Gedebage area in Bandung basin was taken as a model case. The model box was filled with soil from Gedebage, Bandung. A scenario of exploitation of confined groundwater and weight of building was applied for the model case. The results show that the laboratory prototype can monitor the subsurface changes due to the applied anthropogenic forces. In the case of Bandung soil, groundwater exploitation did not immediately cause subsidence instantaneously. There is a time delay between the drawdown of groundwater level and the subsequent vertical deformation. The rate of subsidence varies spatially inside the tank, the largest is close to the pump well and surface loads. A maximum of 2.88 mm subsidence over 663 days was recorded following 1 m groundwater drawdown. This information asserts the importance of long-time monitoring in subsidence areas.

From two-dimensional to three-dimensional marine spatial planning methodology: A case study of Qidong

The oceans are three-dimensional (3D) spaces, resource redistribution has long tended to involve two-dimensional (2D) planning, which has obscured the resource attributes and ecological features of the ocean's different layers, and is prone to cause erroneous sea-use conflicts. This study established a new 3D marine spatial planning (MSP) method consisting of ecological protection zoning (EPZ) and intensive sea-use zoning (ISZ) programs involving marine 3D spatial laying: EPZ was determined using a Marxan model. Based on spatial idleness and environmental friendliness principles, and appropriate newly added sea-use activities were designed to form synergistic sea-use combinations to establish an ISZ program. A case study of Qidong was conducted to test the applicability of the 3D planning program and compare the differences in the zoning results according to the two scenarios of ecological protection and exploitation. Results indicated that EPZ of mid-bottom waterbodies accounted for the highest proportion (47.62%). The best solutions and planning units selected frequency grading could be achieved separately for two scenarios of EPZ. For ISZ, the zoning for both scenarios achieves a synergistic effect between the newly added sea-use activities in the transportation zone; through the northward shift of sea-use in the southern fairway of Qidong, this sea-use activity converted the initially antagonistic attributes with the ecological protection zone to a synergistic purpose. Differences in the results of the intensive sea use zoning between the two scenarios were manifested in the EPZ and surrounding sea use activities, focusing on fishing and ecological control zones and the arrangement of wind power. The 3D MSP methods can address the conflict between some sea-use activities in 2D planning and the conflict between stakeholders competing for the sea-use right, and it also provides a solution for the coastal government to redistribute the marine resources and coordinate the sea-use elements. The relevant practice can provide theoretical and technical support for ecological protection, intensive and economical utilization of marine spatial resources, and national spatial planning framework improvement.

Vulnerability Exploitation Risk Assessment Based on Offensive Security Approach

Security incidents targeting control systems and the industrial internet of things (IIoT) are on the rise as attackers gain a better understanding of the nature of these systems and their increasing connectivity to information technology (IT). Every year, the number of vulnerabilities associated with these incidents increases, making it impractical to apply timely patches for all of them. The current vulnerability assessments, which are the basis for vulnerability patching, have limitations in that they do not adequately reflect the risk of exploitation in the real world after discovery and do not consider operational technology (OT) and industrial control system (ICS) environments other than IT environments. This study proposes to evaluate exploit risk in real-world environments by considering OT/ICS environments and calculating three metrics, including exploit chain risk, exploit code availability, and exploit use probability based on cyber threat information, including IIoT vulnerability data, used in OT/ICS environments. In addition, we construct exploitation scenarios in a control system environment to prioritize vulnerabilities with a high risk of exploitation based on the three metrics. We show that by assessing the risk of attackers’ intentions and exploited technologies for attacks against IIoT devices in a control system environment, we can provide defenders with comprehensive attack risk information for proactive defense.

Interface-Based Search and Automatic Reassembly of CAD Models for Database Expansion and Model Reuse

This paper introduces a new framework for reassembling CAD models of mechanical parts. The generated CAD assemblies are well-constrained, with collision-free parts, and they are ready-to-use for downstream applications. First, input dead CAD models candidate for the reassembly are sorted following a part-by-part interface-based identification algorithm that is capable of characterizing each part according to the assembly slots and interfaces it offers. The slots are then hashed, and the resulting keys are used for fast search of parts in the database. Thus, the parts that can be assembled are quickly identified, and their assembly can be considered according to various scenarios. To support the reassembly steps and satisfy the constraints associated with the specified interfaces, a collision-free kinematic constraint solver is also proposed. During the reassembly steps, the geometry of the slots can also be automatically modified to adjust their dimensions, in order to ensure a perfect fit and to avoid interference at the level of the interfaces. The resulting database can also be further expanded while modifying the relative positions/orientations of the assembled parts. The approach is illustrated on several test cases covering different exploitation scenarios, ranging from simple model reuse to database expansion for machine learning-based applications. Such an automatic reassembly process is particularly innovative, and it clearly paves the way for smart assembly procedures.

Use of geothermal energy to prevent road pavement icing and damage in cold climate areas

In cold climate or alpine regions, freezing temperatures and snow can result into road icing, with consequent threat of the circulation security (Figure 1(a)). When the road surface temperature goes below zero, not only the road surface ices, but also the soil below the pavement can undergo freezing. The phenomenon of soil freezing is complex due to the multi-phase and porous nature of the soil itself. Generally speaking, as ice expands in the soil pores, the soil volume increases (of about 9%, depending on the soil porosity and water saturation). This can induce frost heaving, with consequent damage of the road pavement. In this framework, the possibility to use geothermal energy systems embedded in tunnel linings for road pavement de-icing has rarely been investigated. In such systems, the concrete tunnel lining is equipped with a circuit of pipes, in which a heat carrier fluid circulates and exchanges heat with the ground. As the rock or soil around the tunnel is generally hotter than the external air temperature, heat is extracted from the rock or soil to the fluid, transported through the pipes circuit outside the tunnel, and used to de-ice the pavement road.
 The objective of this study is to go a step forward in the investigation of this innovative application, for both road de-icing and prevention of frost heave. A portion of a geothermally activated tunnel and its connection to a road pipe circuit was simulated numerically (Figure 1 (b)). Appropriate climatic conditions were considered as boundary conditions at the surface level and inside the tunnel, according to available data. The efficiency of the technology was investigated under different climatic and exploitation scenarios. Figure 1 (c) shows as an example the thermal field obtained after the activation of the geothermal plant. The evolution of temperature on the road pavement surface and at the road pipes depth (30 cm from the road pavement surface) are presented on Figure 2 (a), together with the evolution of the external air and tunnel temperature, imposed as boundary conditions according to the monitored climatic conditions in the city of Oslo [1].
 The geothermal system was activated after two years of simulation, by changing the fluid pipes velocity from 0 (non active system) to 0.9 m/s (purple curve on the right axis on Figure 2 (a)). The results show that the road temperature increases thanks to the activation of the system (i.e. when the fluid pipes velocity is imposed to 0.9 m/s).
 Furthermore, a recently developed thermo-hydro-mechanical constitutive model for frozen soils [2] was used to quantify the soil heave due to freezing, with and without the activation of the geothermal system. For this purpose, a similar numerical model has been developped where a column of saturated soil below the road and the tunnel were modelled. The phreatic water table is at the ground surface level and gravity as well as the geostatic stress conditions are considered. The soil is a clay with a low hydraulic conductivity of Kw=4.1×10-10 m/s and a thermal conductivity of Γ=2.35 W/m/K. The other soil properties are: soil stiffness E=100 MPa, Poisson’s ratio ν=0.3, porosity n=0.25, solid grain thermal volumetric expansion coefficient αs=3.4×10-4 K-1. The same soil surface climatic conditions used in the first part were applied. The temperature evolution obtained in the road from the previously mentioned analyses (Figure 2 (a)) was imposed to reproduce the effect of the geothermal activation on the road behaviour. Furthermore, the soil surface is free of stress to study the soil swelling and settlement. The bottom limit of the soil column is hydraulically drained and allows heat flux (at constant liquid pressure and temperature). The lateral far field boundaries are thermally adiabatic, hydraulically impervious, and with oedometric conditions. The results were firstly compared with the case without geothermal activation to quantify the effects in terms of road heave and settlement (Figure 2 (b)). Swelling and settlement are due to thermal expansion and compression of the soil under positive temperature (T>0°C) and to frost heave and thaw settlement under negative temperature (T<0°C). The liquid pressure at the road surface is also depicted (Figure 2 (b)). These results and comparisions allowed understanding the performance of the technology in reducing road mechanical damage induced by freezing.

“Local people want to keep their sand”: Variations in community perceptions and everyday resistance to sand mining across the Red River, Vietnam

The Red River Delta is Vietnam's most densely populated catchment, with its communities intertwined with, and dependent upon, the delta and its resources. Intensive, widespread riverine sand extraction is linked to substantial degradation of the delta, directly threatening these livelihoods. The response of rural communities is to resist in various ways, dependent upon a complex matrix of geospatial factors. Using an ethnographic approach, we explore factors contributing to the scale and patterns of resistance to sand mining of both an upstream riverine community and downstream coastal community in the Red River Delta. The riverine community protest openly to illegal mining directly threatening their river-connected livelihoods, manifest through reporting to authorities, bankside protests and involvement of mass media. In contrast, the coastal community have shifted from open protest, through openly reporting to the authorities, to closed forms of within-village gossip. Here, resistance patterns are driven by proximity to mining sites, perceived impact of mining, and pre-existing structural legislative mechanisms. Under scenarios of rapidly increasing rates of sand extraction to satisfy wider global needs, there is an urgent need for studies of local-scale impacts and resistance, capturing socio-economic characteristics of communities, to better plan for future scenarios of resource extraction and exploitation.

Techno-economic evaluation of the electrochemical production of renewable ethylene oxide from fluctuating power sources and CO2

We present a techno-economic assessment of a novel ethylene oxide (EO) production process, which converts carbon dioxide (CO2) and water electrocatalytically to ethylene (C2H4) and hydrogen peroxide (H2O2), which are further synthesized into EO. To ensure environmental sustainability, the primary focus was on available CO2 from biogenic sources (biomethane and bioethanol plants) and renewable power sources (wind and photovoltaics) for decentralized applications. Accordingly, data on existing European CO2 and renewable power sources were compiled for spatial analysis to develop technology roll-out and exploitation scenarios: 175 suitable locations were identified. Focusing on three locations, the production costs of EO and the product mix were calculated, considering various energy sources and plant configurations (as of 2030 and 2040). For a generic scenario, considering CO2 to be available free of cost (existing biomethane upgrading) and electricity cost of 36€/MWh, the production cost of the product mix (EO, H2O2, methane, hydrogen) amount to 0.86 €/kg. This is at a similar order of magnitude as assessments on other Power-to-X value chains. Assuming that EO is the only utilizable product, the costs increase to 5.78 €/kg, which is significantly higher than for fossil alternatives. According to the sensitivity analysis, energy efficiency, electricity prices, and capital expenditure are the most relevant factors. Regarding the latter, an extended plant lifetime is a crucial factor.

STUDY OF SAND PRODUCTION STAGES IN SHALLOW OIL FIELDS

This article presents the High Pressure Consolidation System (HPСS) and a new experimental method for studying sand behavior in weak sandstone reservoirs. Under laboratory conditions, geostress conditions during the process of rock sedimentation, perforation, and sand production were replicated using a large artificial sample. A comprehensive investigation of sand production phenomena was conducted, where rock and pore pressures were fully controlled throughout the experiment using a computer. The HPCS also allows the study of single-phase and multiphase flow behavior in porous media at realistic reservoir pressures to model various well exploitation scenarios, such as implementing different depletion factors and water-oil ratios.

A study on fly ash, M−Sand and bottom ash incorporated ecological geo polymer blocks with banana fiber

In the modern era, global warming happens to a critical green concern. Every year, the magnitude of greenhouse gas emanation to the ambience is in increasing trend In the scenario of throw-away exploitation and making of ecological geopolymer blocks, the probability in entirety substitution of fly ash as a primary binder instead cement and incorporation of manufactured sand and bottom ash in ecological geo-polymer composite was explored This experimental study aims to investigate the properties of Incorporating M−Sand, Bottom Ash and fly ash geo polymer composites by using banana fibers.Variations in the mechanical characteristics of Ecological geopolymer composites concerning diverse concentrations of inorganic water-soluble bases solution were considered. Geo composites with natural sand with 6 m, 8 m, 10 m, 12 m and 14 m were considered. For each molarity of concentration compressive and, flexural strength were performed on fly ash geopolymer composites. On the investigation, it is concluded that the optimal molarity ratio is 12 m. The optimum molarity ratio was kept constant for the partial replacement of river sand with M−Sand. In this research, Geopolymer composites were partially replaced for river sand in the percentage proportions of 20%, 40%, 60%, 80% and 100% with manufactured sand. Investigation reveals that optimal compressive characteristics were achieved for geopolymer composite with 40% replacement of river sand with M−Sand. Furthermore with 40% replacement of M.sand for river sand as constant, partial replacement of bottom ash for river sand was done. The bottom ash was added with MS40 mix proportions with the percentages of 10, 20, 30, 40 and 50 as a partial replacement with river sand and the optimum replacement of bottom ash was identified at 40% to be optimum based on test results. Durability and microstructural studies were carried out for was also conducted Banana fibre-embedded MS40BA40 geopolymer composite compressive characteristics, with the fiber of length 30 mm and 0, 5, 7.5, 10, and 12.50 % of geopolymer composites on ecological geopolymer composite was investigated.

Assessment of the hydrochemical composition of groundwater and development of new operating scenarios for water supply (Tajikistan)

The main study task was dictated by the growth rate of water consumption, namely the development of new scenarios for the exploitation of groundwater for water supply purposes. The assessment of surface and groundwater quality in the area showed a tendency to increase mineralization, hardness, a number of chemical components (up to exceeding the limited concentration). Analysis and interpretation of long-term groundwater chemical data, as well as the intensity of surface runoff, within the study area, allowed us to identify anthropogenic influence on the amount of runoff. According to the results of the study, the growth of infiltration nutrition (due to the expansion of irrigation areas) is reflected into deterioration of groundwater quality. In addition, the existing water intakes are located within the city limits, which creates an additional threat of bacterial and organic pollution. The new scenarios of groundwater exploitation are based on the features of the hydrogeological section, the results of hydrochemical studies, the amount of groundwater reserves of individual aquifers, calculations of sanitary protection zones of water intakes. The Amwells module (ANSDIMAT software package) was used to estimate groundwater reserves, so an analytical model was created based on the actual material. Thus, an extremely demanded detailed characterization of the groundwater of the studied area was carried out, some of which are suitable for use as drinking water.

Beyond deep-sea mining sublethal effects: Delayed mortality from acute Cu exposure of the cold-water octocoral Viminella flagellum.

The potential release of metals, especially copper (Cu) during mining of seafloor massive sulphides (SMS), represents a potential toxicological threat to cold-water coral (CWC) habitats. Herein, we evaluated for the first time the response of the whip coral Viminella flagellum to short-term acute Cu exposure. Nubbins of V. flagellum were exposed to Cu concentrations of 0 (control); 60; 150; 250; 450 and 600μg/L for 96h. After exposure, V. flagellum nubbins were transferred to a continuous flow-through aquarium and feed once a day for 3weeks. No immediate mortality was detected during the short-term Cu exposure. However, a delayed mortality, which was concentration dependent was observed. The first signs of tissue loss occurred after 1week of recovery in non-contaminated conditions in V. flagellum nubbins previously exposed to Cu concentrations of 60 and 150μg/L followed by nubbins exposed to Cu concentrations of 250, 450μg/L after 2weeks and 600μg/L after 3weeks. A delayed mortality impact should be considered in future Cu tolerance experiments and scenarios of deep-sea mining exploitation.

Is restricting catch to young sharks only more sustainable? Exploring a controversial management strategy for bull, tiger, blue and bonnethead sharks

AbstractProper management of shark populations is an immediate concern due to their high vulnerability. In this study, we applied stochastic demographic models for four shark species (bull shark Carcharhinus leucas, tiger shark Galeocerdo cuvier, blue shark Prionace glauca and bonnethead Sphyrna tiburo) to test how population growth behaved under different exploitation scenarios, such as the exclusion of older sharks from fisheries. Populations grew at considerably slow rates when unfished, except for P. glauca. When fisheries targeted all individuals, populations started to decline at generally very low fishing mortality and harvest rates. Conversely, when adult individuals were excluded from fisheries, population resiliency increased despite higher fishing pressures, with no negative growth rates even if harvest levels were doubled. This study indicates that conservation of these species may benefit from protecting adult stocks.

Environmental impact assessment of guided wave-based structural health monitoring

Guided wave-based structural health monitoring (GW-SHM) relies on permanently installed sensors to detect and monitor structural defects such as cracks or delamination. Millimeter to centimeter-sized defects are detected over areas of several square meters with sparse sensor networks installed on metallic or composite structures. So far, the main drivers of the development of such technologies have been expectations of cost savings and/or an increased safety. As monitoring requires a complex cyber physical system including, at least an energy source, sensors, data acquisition, treatment, and communication capabilities, adding monitoring capabilities to a structure leads to an intrinsic environmental impact. This paper targets for the first time the environmental assessment of GW-SHM. Such analysis being use-case dependent, two prospective applications are studied: railroad monitoring and wind turbine monitoring. A complete GW-SHM system prototype is defined to quantify its environmental impact, and exploitation scenarios are proposed to estimate the potential environmental gains provided by the monitoring. For the scenarios under consideration, the studied system is found to be either carbon neutral or carbon negative (i.e., favorable), but this result is limited to the functional units under consideration. The present study is expected to be a template for further environmental assessments of monitoring systems, which shall be conducted for each prospective application and refined often as systems mature and exploitation scenarios become clearer and exploitation data available.

Rational Guidelines for the Two-Step Scalability of Enzymatic Polycondensation: Experimental and Computational Optimization of the Enzymatic Synthesis of Poly(glycerolazelate).

The lipase‐catalyzed polycondensation of azelaic acid and glycerol is investigated according to a Design‐of‐Experiment approach that helps to elucidate the effect of experimental variables on monomer conversion, M n and regioselectivity of acylation of glycerol. Chemometric analysis shows that after 24 h the reaction proceeds regardless of the presence of the enzyme. Accordingly, the biocatalyst was removed after a first step of synthesis and the chain elongation continued at 80 °C. That allowed the removal of the biocatalyst and the preservation of its activity: pre‐requites for efficient applicability at industrial scale. The experimental study, combined with docking‐based computational analysis, provides rational guidelines for the optimization of the regioselective acylation of glycerol. The process is scaled up to 73.5 g of monomer. The novelty of the present study is the rigorous control of the reaction conditions and of the integrity of the immobilized biocatalyst, which serve to avoiding any interference of free enzyme or fines released in the reaction mixture. The quantitative analysis of the effect of experimental conditions and the overcoming of some major technical bottlenecks for the scalability of enzymatic polycondensation opens new scenarios for industrial exploitation.

Fishery Dynamics, Status, and Rebuilding Based on Catch-Only Data in Coastal Waters of China

China has become the largest contributor to marine fisheries in the world with its fishing fleets explosively increasing their fishing effort and resulting catch, but its fishery composition and sustainability have deteriorated. Limited information on fishery exploitation status encumbers effective resource management. In this study, a data-poor Monte Carlo method, the Catch-Maximum Sustainable Yield (CMSY) method, was used to estimate the historical exploited dynamics and current stock status of ten Chinese economic marine fish stocks, includingTrichiurus lepturus,Larimichthys crocea,Larimichthys polyactis,Thamnaconus modestus,Scomberomorus niphonius,Ilisha elongate,Decapterus maruadsi,Scomber japonicus,Engraulis japonicus, andClupea pallasii, which accounted for about 50% of total fish catches in the coastal waters of China and covered five functional groups (i.e., large, medium benthopelagic, large, medium, and small pelagic). SpeciesL. croceaandL. polyactishad been subjected to overfishing since the 1950s. The others showed a decreasing trend in biomass along with the explosively increasing fishing efforts since the 1990s. Benthopelagic fish experienced overfishing pressure about a decade earlier than pelagic species. All the fish stocks investigated in this study were depleted (current biomass lower than the biomass capable of producing maximum sustainable yields, i.e.,B<Bmsy) in 2019, and most species were still facing high-fishing pressure (current fishing mortality higher than the mortality capable of producing maximum sustainable yields, i.e.,F>Fmsy). Also, a Schaefer model was used to assess stocks rebuilding status until 2030 under four exploitation scenarios, i.e., fishing mortality equals 0.5, 0.6, 0.8, or 0.95 timesFmsy. Most species stocks will likely recover to theBmsy, which indicates that reduction of fishing pressure is probably the most effective way for fishery recovery.

User-Driven Computer-Assisted Reverse Engineering of Editable CAD Assembly Models

Abstract This paper introduces a novel reverse engineering (RE) technique for the reconstruction of editable computer-aided design (CAD) models of mechanical parts’ assemblies. The input is a point cloud of a mechanical parts’ assembly that has been acquired as a whole, i.e., without disassembling it prior to its digitization. The proposed framework allows for the reconstruction of the parametric CAD assembly model through a multi-step reconstruction and fitting approach. It is modular and it supports various exploitation scenarios depending on the available data and starting point. It also handles incomplete datasets. The reconstruction process starts from roughly sketched and parameterized CAD geometries (i.e., 2D sketches, 3D parts, or assemblies) that are then used as input of a simulated annealing-based fitting algorithm, which minimizes the deviation between the point cloud and the adapted geometries. The coherence of the CAD models is maintained by a CAD modeler that performs the geometries’ updates while guaranteeing the possibly imposed constraints and model coherence. The optimization process leverages a two-level filtering technique able to capture and manage the boundaries of the geometries inside the overall point cloud in order to allow local fitting and interfaces detection. It is a user-driven approach where the user decides what are the most suitable steps and sequence to operate. It has been tested and validated on both real scanned point clouds and as-scanned virtually generated point clouds incorporating several artifacts that would appear with real acquisition devices.

A Circular Approach to Upgrade Cement-based CO2 and Renewable H2: Techno-economic Analysis of SNG Production

The present work introduces a feasible, carbon-free integrated process that is based on the catalytic hydrogenation of industrially captured CO2 via green H2 towards the production of synthetic natural gas (SNG). Overall, three systems are being assessed from an economic point of view (sizing and simulation through Aspen Plus and HOMER software): a) H2 production through a combination of renewable energy sources (RES) and water electrolysis, b) cement-based CO2 capture through amines in a continuous absorption/regeneration cycle and c) CO2 catalytic hydrogenation. The basis for the process simulation and the subsequent economic analysis lies on the exploitation of 1,400 kt/y CO2 that are emitted from a typical cement industrial plant. According to this capacity, the integrated system is assessed for a yearly SNG production rate of ~500 kt/y. As was derived from the screening of different market exploitation scenarios (e.g., funding options, increase of CO2 tariffs), a sustainable and feasible solution can be achieved (based on current market values), as long as the RES-H2 system is funded by up to ~35 % or CO2 penalty costs reach levels of >140 €/t in the near future.