Procedural approach to volumetric terrain generation

The recent outbreak of indie games has popularized volumetric terrains to a new level, although video games have used them for decades. These terrains contain geological data, such as materials or cave systems. To improve the exploration experience and due to the large amount of data needed to construct volumetric terrains, industry uses procedural methods to generate them. However, they use their own methods, which are focused on their specific problem domains, lacking customization features. Besides, the evaluation of the procedural terrain generators remains an open issue in this field since no standard metrics have been established yet. In this paper, we propose a new approach to procedural volumetric terrains. It generates completely customizable volumetric terrains with layered materials and other features (e.g., mineral veins, underground caves, material mixtures and underground material flow). The method allows the designer to specify the characteristics of the terrain using intuitive parameters. Additionally, it uses a specific representation for the terrain based on stacked material structures, reducing memory requirements. To overcome the problem in the evaluation of the generators, we propose a new set of metrics for the generated content.     

Unsteady and non-linear aeroelastic analysis of large horizontal-axis wind turbines

Analysis results, obtained from numerical simulation, for non-linear and unsteady aeroelastic behavior of large horizontal-axis wind turbines are presented in this paper. Simulations are carried out using a partitioned scheme of weak interaction that allows dealing with the fluid–structure interaction problem by using one method to solve the structural-dynamic problem and another method for the aerodynamic problem.     

Optimal reconfiguration of water networks based on properties

This paper presents a mathematical programming model for the reconfiguration of existing water networks based on the stream properties that impact the performance of the process units and the environment. To develop an improved configuration, the model simultaneously evaluates the repiping of the existing network through the placement/reassignment of the existing treatment units, and the addition of new treatment units while addressing environmental constraints. The model also accounts for the options of process modification and increased capacity of the plant. The objective function of the optimization model seeks to minimize the total annualized cost of the system which incorporates the capital investment associated with process retrofitting and the operating cost which includes the cost of fresh resources. The applicability of the proposed model is illustrated through several case studies.     

Validation of multibody modeling and simulation using an instrumented bicycle: from the computer to the road

This paper describes the use of an instrumented bicycle and its computational model for teaching multibody dynamics. The presented approach employs the Whipple model for the kinematic and inverse dynamic simulation of a bicycle ride using as an input three generalized coordinates registered with digital sensors. During the experimental phase, students ride the instrumented bicycle to collect the necessary sensor data. The kinematic and inverse dynamic simulations based on these signals provide a full picture of the motion of the system in different positions and at a range of velocities and accelerations. In addition, they estimate the traction, control, and tire-to-road contact forces during the ride. To validate the simulated results, the simulated velocity and accelerations are compared with the data acquired with an inertial measurement unit (IMU) installed on the bicycle. The paper describes the experimental setup of the instrumented bicycle, enabling readers to build the very same system for their own educational use. The instrumented bicycle system is based on open-source software and as much as possible on open hardware.     

Deformation at ambient and high temperature of in situ Laves phases-ferrite composites

The mechanical behavior of a Fe₈₀Zr₁₀Cr₁₀ alloy has been studied at ambient and high temperature. This Fe₈₀Zr₁₀Cr₁₀ alloy, whoose microstructure is formed by alternate lamellae of Laves phase and ferrite, constitutes a very simple example of an in situ CMA phase composite. The role of the Laves phase type was investigated in a previous study while the present work focuses on the influence of the microstructure length scale owing to a series of alloys cast at different cooling rates that display microstructures with Laves phase lamellae width ranging from ～50 nm to ～150 nm. Room temperature compression tests have revealed a very high strength (up to 2 GPa) combined with a very high ductility (up to 35%). Both strength and ductility increase with reduction of the lamella width. High temperature compression tests have shown that a high strength (900 MPa) is maintained up to 873 K. Microstructural study of the deformed samples suggests that the confinement of dislocations in the ferrite lamellae is responsible for strengthening at both ambient and high temperature. The microstructure scale in addition to CMA phase structural features stands then as a key parameter for optimization of mechanical properties of CMA in situ composites.     

Materials Fabrication from Native and Recombinant Thermoplastic Squid Proteins

Natural elastomers made from protein extracts have received significant interest as eco‐friendly functional materials due to their unique mechanical and optical properties emanating from secondary structures. The next generation sequencing approach is used to identify protein sequences in a squid ring teeth complex extracted from Loligo vulgaris and the use of recombinant expression is demonstrated in the fabrication of a new generation of thermoplastic materials. Native and recombinant thermoplastic squid proteins exhibit reversible solid to melt phase transition, enabling them to be thermally shaped into 3D geometries such as fibers, colloids, and thin films. Direct extraction or recombinant expression of protein based thermoplastics opens up new avenues for materials fabrication and synthesis, which will eventually be competitive with the high‐end synthetic oil based plastics.     

A reduced-order model based on the coupled 1D-3D finite element simulations for an efficient analysis of hemodynamics problems

A reduced-order model for an efficient analysis of cardiovascular hemodynamics problems using multiscale approach is presented in this work. Starting from a patient-specific computational mesh obtained by medical imaging techniques, an analysis methodology based on a two-step automatic procedure is proposed. First a coupled 1D-3D Finite Element Simulation is performed and the results are used to adjust a reduced-order model of the 3D patient-specific area of interest. Then, this reduced-order model is coupled with the 1D model. In this way, three-dimensional effects are accounted for in the 1D model in a cost effective manner, allowing fast computation under different scenarios. The methodology proposed is validated using a patient-specific aortic coarctation model under rest and non-rest conditions.     

Evaluation of the chemical composition and colour in long‐life tomatoes (Lycopersicon esculentum Mill) dehydrated by combined drying methods

When tomatoes are submitted to treatments of drying, depending on the parameters and methods used, the concentration or degradation of nutrients can occur. The changes in the composition and colour were verified when different drying processes were used. Freeze drying, oven drying, the combination of both and also the effect of the pretreatment (blanching) using steam were studied. The fresh tomato composition was compared with the composition of dehydrated tomato powder. After dehydration, the moisture content reduced 78% from the total initial moisture. In addition, a nutrient concentration was observed with an increase of about 57% of citric acid content and 3% in the pH. The ash content also increased from 0.53% to 8% (15 times) and 60%, the carbohydrates from 3.94% to 60% (15 times) and the proteins were increased from 1% to 11% (10 times). The blanching resulted in different types of changes, such as greater stability for the proteins, carbohydrates, fat, lycopene and β‐carotene.     

Parameters affecting the life cycle performance of PV technologies and systems

This paper assesses modeling parameters that affect the environmental performance of two state-of-the-art photovoltaic (PV) electricity generation technologies: the PVL136 thin film laminates and the KC120 multi-crystalline modules. We selected three metrics to assess the modules’ environmental performance, which are part of an actual 33 kW installation in Ann Arbor, MI. The net energy ratio (NER), the energy pay back time (E-PBT), and the CO₂ emissions are calculated using process based LCA methods. The results reveal some of the parameters, such as the level of solar radiation, the position of the modules, the modules’ manufacturing energy intensity and its corresponding fuel mix, and the solar radiation conversion efficiency of the modules, which affect the final analytical results. A sensitivity analysis shows the effect of selected parameters on the final results. For the baseline scenario, the E-PBT for the PVL136 and KC120 are 3.2 and 7.5 years, respectively. When expected future conversion efficiencies are tested, the E-PBT is 1.6 and 5.7 years for the PVL136 and the KC120, respectively. Based on the US fuel mix, the CO₂ emissions for the PVL136 and the KC120 are 34.3 and 72.4 g of CO₂/kW h, respectively. The most effective way to improve the modules’ environmental performance is to reduce the energy input in the manufacturing phase of the modules, provided that other parameters remain constant. Consequently, the use of PV as an electricity source during PV manufacturing is also assessed. The NER of the supplier PV is key for the performance of this scheme. The results show that the NER based on a PV system can be 3.7 times higher than the NER based on electricity supplied by the traditional grid mix, and the CO₂ emissions can be reduced by 80%.