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Showing records 36534 to 36558 of 43292. [First] Page: 1 1459 1460 1461 1462 1463 1464 1465 1466 1467 Last
The Engine Combustion Phasing Prediction Based on the Support Vector Regression Method
Qifan Wang, Ruomiao Yang, Xiaoxia Sun, Zhentao Liu, Yu Zhang, Jiahong Fu, Ruijie Li.
February 21, 2023 (v1)
Keywords: combustion phasing prediction, ignition-spark engine, machine learning method, support vector regression
While traditional one-dimensional and three-dimensional numerical simulation techniques require a lot of tests and time, emerging Machine Learning (ML) methods can use fewer data to obtain more information to assist in engine development. Combustion phasing is an important parameter of the spark-ignition (SI) engine, which determines the emission and power performance of the engine. In the engine calibration process, it is necessary to determine the maximum brake torque timing (MBT) for different operating conditions to obtain the best engine dynamics performance. Additionally, the determination of the combustion phasing enables the Wiebe function to predict the combustion process. Existing studies have unacceptable errors in the prediction of combustion phasing parameters. This study aimed to find a solution to reduce prediction errors, which will help to improve the calibration accuracy of the engine. In this paper, we used Support Vector Regression (SVR) to reconstruct the mapping r... [more]
Photodegradation of Decabrominated Diphenyl Ether in Soil Suspensions: Kinetics, Mechanisms and Intermediates
Kaibo Huang, Haozhong Lin, Xueqin Tao, Mengyao Zou, Guining Lu.
February 21, 2023 (v1)
Subject: Materials
Keywords: BDE-209, mechanism, photodegradation, products, soil suspension
Pollution by polybrominated diphenyl ethers (PBDEs) is a major concern due to their bioaccumulation, persistence, and carcinogenicity. This study aimed to investigate the decabrominated diphenyl ether (BDE-209) photodegradation in soil suspensions. The results indicate BDE-209 can degrade in soil suspensions and its degradation follows pseudo-first-order kinetics. The light sources and intensity effects were studied and the photodegradation rates were 500 W Mercury Lamp > 300 W Mercury Lamp > 500 W Xenon Lamp > 300 W Xenon Lamp, which indicates UV light is the main reason for BDE-209 degradation. Soil particle inhibits BDE-209 photodegradation due to the light-shielding effect. BDE-209 photodegradation rates increased from 0.055 to 0.071 h−1 with pH value increasing from 3.5 to 9.5. This may be because the products are more easily produced in higher pH soil suspensions. The presence of humic acid (HA) may inhibit BDE-209 photodegradation by photo-shielding. Fe3+ and Cu2+ have an advers... [more]
A Combinatorial Approach towards Antibacterial and Antioxidant Activity Using Tartaric Acid Capped Silver Nanoparticles
Irshad Begum, Sana Shamim, Fuad Ameen, Zahid Hussain, Sartaj Ahmad Bhat, Tahir Qadri, Mumtaz Hussain.
February 21, 2023 (v1)
Subject: Materials
Keywords: antibiotics, antioxidant, capped, one-pot synthesis, silver nanoparticles, tartaric acid
The convenient synthetic strategy for the one-pot synthesis of silver nanoparticles capped by tartaric acid with a controlled size is reported here. Their characterization is revealed through spectroscopic protocols, such as UV/Vis and FTIR, while SEM, DLS and a Zetasizer revealed the surface morphology, size distribution and surface charge on the nanoparticles. The surface plasmon resonance (SPR) band was observed at 406 nm with 1.07 a.u absorbance, the image for SEM shows that the particles were monodispersed and spherical in shape, while the z-average size distribution of AgNPs/TA in a colloidal solution was found to be 79.20 nm and the surface charge was monitored as −28.2 mV. The antibacterial activities of these capped nanoparticles alone and in synergism with selected fluoroquinolones (ofloxacin, sparfloxacin, ciprofloxacin and gemifloxacin) and macrolides (erythromycin and azithromycin) were assessed on selected Gram-negative as well as Gram-positive organisms by employing the... [more]
Need for a Next Generation of Chromatography Models—Academic Demands for Thermodynamic Consistency and Industrial Requirements in Everyday Project Work
Florian Lukas Vetter, Jochen Strube.
February 21, 2023 (v1)
Keywords: adsorption thermodynamics, biochromatography, digital twins, Modelling, process chromatography
Process chromatography modelling for process development, design, and optimization as well as process control has been under development for decades. Still, the discussion of scientific potential and industrial applications needs is open to innovation. The discussion of next-generation modelling approaches starting from Langmuirian to steric mass action and multilayer or thermodynamic consistent real and ideal adsorption theory or colloidal particle adsorption approaches is continued.
A Review of Stand-Alone and Hybrid Microbial Electrochemical Systems for Antibiotics Removal from Wastewater
Basem S. Zakaria, Bipro Ranjan Dhar.
February 21, 2023 (v1)
Subject: Biosystems
Keywords: antibiotics, microbial electrochemical technologies, microbial fuel cells, wastewater treatment
The growing concern about residual antibiotics in the water environment pushes for innovative and cost-effective technologies for antibiotics removal from wastewater. In this context, various microbial electrochemical systems have been investigated as an alternative to conventional wastewater technologies that are usually ineffective for the adequate removal of antibiotics. This review article details the development of stand-alone and hybrid or integrated microbial electrochemical systems for antibiotics removal from wastewater. First, technical features, antibiotics removal efficiencies, process optimization, and technological bottlenecks of these systems are discussed. Second, a comparative summary based on the existing reports was established to provide insights into the selection between stand-alone and hybrid systems. Finally, research gaps, the relevance of recent progress in complementary areas, and future research needs have been discussed.
Using Linkography and Situated FBS Co-Design Model to Explore User Participatory Conceptual Design Process
Juan Cao, Wu Zhao, Huicong Hu, Yeqi Liu, Xin Guo.
February 21, 2023 (v1)
Keywords: design cognition, linkography, situated FBS, user participatory design
To unravel the complex challenges addressed by product innovation, it is oftentimes essential for users to participate in the design process. However, there is a paucity of research in terms of in-depth exploration of the cognitive patterns and dynamic design processes of co-design with user participation in the existing design cognition research. The current study aimed to investigate the cognition activities involved in the process of co-design between user and designer at both the individual and team levels. The combination method of linkography and the situated function−behavior−structure (FBS) co-design model was carried out to encode and analyze the protocol data. The results showed that, at the individual level, designers and users adopted different design strategies to promote the progress of the design. In addition, the interaction activities among users and designers varied in different co-design processes. However, at the team level, the collaborators showed systematic think... [more]
Environmental Aspects of the Combined Cooling, Heating, and Power (CCHP) Systems: A Review
Mohsen Salimi, Morteza Hosseinpour, Shabnam Mansouri, Tohid N.Borhani.
February 21, 2023 (v1)
Subject: Environment
Keywords: carbon footprint, CCHP, LCA, renewables, water footprint
Expanding cities means increasing the need for energy in the residential sector. The supply of this energy must be in environmentally friendly ways; one method of meeting demand in the residential sector is the use of combined cooling, heating, and power (CCHP) systems. The current review paper shows that due to the high cost of gas and electricity, CCHP can be used in various sectors, such as hospitals and airports, to reduce energy consumption with lower environmental impacts by using renewable energy systems as the main driver. While CCHP systems are not feasible in tropical regions with high cooling demand, a solar hybrid system is a superior candidate for regions with sufficient radiation. CCHP can also be used in sectors such as wastewater treatment units, desalination systems, and hydrogen production units to improve performance and increase productivity. The carbon and water footprints of CCHP systems are discussed in detail. The main drivers for reducing carbon and water footp... [more]
Synthetic Biology: A New Era in Hydrocarbon Bioremediation
Valentina Jiménez-Díaz, Aura Marina Pedroza-Rodríguez, Oswaldo Ramos-Monroy, Laura C. Castillo-Carvajal.
February 21, 2023 (v1)
Subject: Environment
Keywords: bioremediation, biosensors, consortium, genetically engineered microorganisms, hydrocarbons, synthetic biology
Crude oil is a viscous dark liquid resource composed by a mix of hydrocarbons which, after refining, is used for the elaboration of distinct products. A major concern is that many petroleum components are highly toxic due to their teratogenic, hemotoxic, and carcinogenic effects, becoming an environmental concern on a global scale, which must be solved through innovative, efficient, and sustainable techniques. One of the most widely used procedures to totally degrade contaminants are biological methods such as bioremediation. Synthetic biology is a scientific field based on biology and engineering principles, with the purpose of redesigning and restructuring microorganisms to optimize or create new biological systems with enhanced features. The use of this discipline offers improvement of bioremediation processes. This article will review some of the techniques that use synthetic biology as a platform to be used in the area of hydrocarbon bioremediation.
A Machine Learning Approach for Phase-Split Calculations in n-Octane/Water and PASN/Water Systems
Sandra Lopez-Zamora, Salvador Escobedo, Hugo de Lasa.
February 21, 2023 (v1)
Keywords: n-octane, PASN, regression, vapor-liquid-liquid equilibrium, Water
Flash calculations, including phase split and phase classification for both n-octane/water blends and paraffinic aromatic synthetic naphtha (PASN)/water blends present significant computational challenges. Calculations to establish the two-phase and three-phase regions, as well as the transitions between regions, were addressed by a phase classification method proposed in a recent contribution involving machine learning (ML). This work focusses on the phase-split calculations, considering (a) the lack of numerical convergence of the traditional calculations and their related numerical issues for water/n-octane and PASN/water systems based on the Rachford−Rice derived surfaces and (b) the successful implementation of an ML approach based on a K-nearest-neighbor (KNN) algorithm, which uses the abundant experimental data obtained in a CREC-VL cell.
A Substrate Integrated Waveguide Resonator Sensor for Dual-Band Complex Permittivity Measurement
Qian Chen, Zhuo Long, Naoki Shinohara, Changjun Liu.
February 21, 2023 (v1)
Subject: Materials
Keywords: measurement, permittivity, resonator sensor, substrate integrated waveguide (SIW)
This paper presents a novel dual-band substrate integrated waveguide (SIW) sensor that is designed to measure the complex permittivities of liquids or solid powders at two industrial, scientific, and medical (ISM) frequencies simultaneously. Resonant frequencies and quality factors are obtained from S-parameter measurements with the proposed SIW sensor, and applied to reconstructing the permittivities of materials under test through an artificial neural network. The water−ethanol mixed liquids were measured with the proposed sensor. The maximum deviations of the measured permittivities at 2.45 and 5.8 GHz are within 3% of literature results. The measurement by the proposed SIW sensor with artificial neural network reconstruction is accurate and efficient.
Artificial Neural Network for Fast and Versatile Model Parameter Adjustment Utilizing PAT Signals of Chromatography Processes for Process Control under Production Conditions
Mourad Mouellef, Glaenn Szabo, Florian Lukas Vetter, Christian Siemers, Jochen Strube.
February 21, 2023 (v1)
Subject: Materials
Keywords: artificial neural networks, chromatography modeling, ion-exchange chromatography, Machine Learning, parameter estimation
Preparative chromatography is a well-established operation in chemical and biotechnology manufacturing. Chromatography achieves high separation performances, but often has to deal with the yield versus purity trade-off as the optimization criterium regarding through-put. The initial trade-off is often disturbed by the well-known phenomenon of chromatogram shifts over process lifetime, and has to be corrected by operators via adjustment of peak fraction cutting. Nevertheless, with regard to autonomous operation and batch to continuous processing modes, an advanced process control strategy is needed to identify and correct shifts from the optimal operation point automatically. Previous studies have already presented solutions for batch-to-batch variance and process control options with the aid of rigorous physico-chemical process modeling. These models can be implemented as distinct digital twins as well as statistical process operation data analyzers. In order to utilize such models for... [more]
Isolation and Analysis of Carotenoids in Hungary from Zechmeister until Today
Attila Agócs, Erika Turcsi, Veronika Nagy, József Deli.
February 21, 2023 (v1)
Subject: Materials
Keywords: carotenoids, column chromatography, detection, HPLC, isolation
László Zechmeister, one of the most important pioneers of carotenoid chemistry, died 50 years ago. He founded a carotenoid research group in Pécs (Hungary), which is the only place in the world where carotenoid research has been conducted continuously over the past 95 years. This review presents the life of Zechmeister and gives a summary about the evolution of the methods of analysis, isolation, and structure elucidation of carotenoids from the 1930s until today, based on the results of the research group founded by Zechmeister.
The Inhibitory Effect of Chitosan Based Films, Incorporated with Essential Oil of Perilla frutescens Leaves, against Botrytis cinerea during the Storage of Strawberries
Dongying Wang, Haoduo Yang, Xinjian Lu, Yichen Wu, Francesca Blasi.
February 21, 2023 (v1)
Keywords: Botrytis cinerea, chitosan films, essential oils, food quality, Perilla frutescens, sensory analysis, strawberries
Reduction in food waste, as well as non-invasive methods for extending the shelf-life of perishable fruits, are important global challenges. To achieve these objectives, in this paper, the use of natural compounds, chitosan films (CS) incorporated with essential oils from leaves, for postharvest fungal protection of strawberries is proposed. In the present study, the CS films incorporated with the essential oil from Perilla frutescens leaves (PFEO) at different concentrations were prepared and employed for packaging strawberries infected by B. cinerea during refrigerated storage at 4 °C for 10 days. Interestingly, the strawberries coated with CS films containing PFEO at 1.0% during this period possessed an effective antimicrobial effect against B. cinerea infection in potato dextrose agar (PDA). Moreover, the quality properties of the strawberries, (i.e., weight loss, firmness index, decay percentage, yeasts/molds, pH value, total soluble solids, titrable acidity, and maturity index),... [more]
Highly Efficient and Rapid Removal of Methylene Blue from Aqueous Solution Using Folic Acid-Conjugated Dendritic Mesoporous Silica Nanoparticles
Abdurrahman A. Almethen, Khalid Mohammed Alotaibi, Haitham S. Alhumud, Abdullah M. Alswieleh.
February 21, 2023 (v1)
Subject: Materials
Keywords: amine-functionalization, cationic dyes, dendritic mesoporous silica nanoparticles, dyes removal, folic acid-conjugation
Dendritic Mesoporous Silica Nanoparticles (DMSNs) are considered superior in the adsorption of unfavorable chemical compounds and biological pollutants. Herein, we have synthesized folic acid-terminated dendritic mesoporous silica nanoparticles (FA-DMSN) for the removal of cationic dyes, methylene blue (MB), from aqueous solutions. The structural, morphological, functional, specific surface area, pore size distribution, and thermal properties of the synthesized DMSNs were identified using a scanning electron microscope (SEM), a transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), Brunauer−Emmett−Teller (BET), and Thermogravimetric Analyzer (TGA). The synthesized DMSNs exhibited a high surface area (521 m2 −1) and pore volume (1.2 cm3 g−1). In addition, it features both wide pore size and narrow distributions, which strongly affect the adsorption performance in terms of the equilibrium uptake time. Moreover, the imp... [more]
Thermal Characteristic Analysis of Sodium in Diluted Oxygen via Thermogravimetric Approach
Fang Chen, Xi-Lin Dong, Yan Tang, An-Chi Huang, Mei-Lin Zhang, Qing-Chun Kang, Zhong-Jun Shu, Zhi-Xiang Xing.
February 21, 2023 (v1)
Keywords: apparent activation energy, oxygen concentration, sodium oxygen reaction, sodium pool fire, thermogravimetric analysis
As the main reactor type of the fourth-generation nuclear power systems, sodium-cooled fast reactors are now designed and built worldwide. A sodium pool cooling circulation process is indispensable in a sodium-cooled fast reactor. However, the sodium pool fire design is the basis of accidents in sodium-cooled fast reactors. The fire hazard caused by the sodium−oxygen reaction and fast reactor safety have attracted extensive attention. Dry powder is widely used as an effective fire-extinguishing agent to control sodium fire. The sodium will burn in an oxygen-depleted atmosphere when using dry powder to cover fire. In this study, the change law of thermogravimetry of melted sodium is studied by thermogravimetric analysis (TGA) and the apparent activation energy (Ea) is obtained, which has a linear relationship with the oxygen concentration. The results can provide a reference for improving the engineering design standards of sodium fire suppression systems and can also be incorporated in... [more]
Culturing Important Plants for Sweet Secondary Products under Consideration of Environmentally Friendly Aspects
Matthias Preusche, Andreas Ulbrich, Margot Schulz.
February 21, 2023 (v1)
Subject: Environment
Keywords: culture systems, Glycyrrhiza glabra, glycyrrhizin, Hydrangea macrophylla, mogrol, phyllodulcin, Rubus suavissimus, Siraitia grosvenorii, Stevia rebaudiana, steviol
Some sweet tasting plant secondary metabolites are non-caloric or low nutritive compounds that have traditional use in food formulations. This mini-review focuses on conventional and advanced cultivation regimes of plants that accumulate sweet tasting or sweet taste modulating secondary metabolites of potential economic importance, in particular mogrosides (Siraitia grosvenorii), phyllodulcin (Hydrangea macrophylla), glycyrrhizin (Glycyrrhiza glabra), steviol glycosides (Stevia grosvenorii), and rubusoside (Rubus suavissimus). Consequential obstacles during the cultivation of Hydrangea macrophylla cultivars outside their natural habitat in a protected cultivation environment are addressed. Culturing at non-habitat locations facilitates short transportation routes of plant material for processing, which can be a key to an economically and environmentally compatible usage. The biosynthetic pathways, as far as known, are shortly mentioned. The proved or hypothetical degradation pathways o... [more]
Object Detection Algorithm for Surface Defects Based on a Novel YOLOv3 Model
Ning Lv, Jian Xiao, Yujing Qiao.
February 21, 2023 (v1)
Keywords: defect detection, K-means++, loss function, object detection, YOLOv3
The surface defects of industrial structural parts have the characteristics of a large-scale span and many small objects, so a novel YOLOv3 model, the YOLOv3-ALL algorithm, is proposed in this paper to solve the problem of precise defect detection. The K-means++ algorithm is combined with the intersection-over-union (IoU) and comparison of the prior box for clustering, which improves the clustering effect. The convolutional block attention module (CBAM) is embedded in the network, thus improving the ability of the network to obtain key information in the image. By adding fourth-scale prediction, the detection capability of a YOLOv3 network for small-object defects is greatly improved. A loss function is designed, which adds the generalized intersection-over-union (GIoU) loss combined with focal loss to solve the problems of L2 loss and class imbalance in samples. Experiments regarding contour-defect detection for stamping parts show that the mean average precision (mAP) of the YOLOV3-A... [more]
Effect of Drying Methods and Processing Conditions on the Quality of Curcuma longa Powder
Sandra M. Llano, Ana María Gómez, Yudy Duarte-Correa.
February 21, 2023 (v1)
Keywords: antioxidant capacity, Curcuma longa, curcuminoids, drying methods, packaging
Turmeric (Curcuma longa) is a spice that has been used for a long time in traditional medicine for its anti-inflammatory properties and recently used in the food industry for its dyeing and flavoring properties. This work studied the effect of different drying methods (convection oven drying, fluidized bed drying, and traditional solar drying) on the quality of Curcuma longa powder. The effect of UV radiation on turmeric powder using different packaging materials (glass, aluminum foil bag, and low-density polyethylene bag), was also studied. Subsequently, the fluidized bed drying method was used to evaluate the effect of drying temperature. The results show that convection and fluidized bed drying had no significant impact on turmeric quality. However, solar drying degraded curcuminoids by 36.5% and the ORAC value decreased by 14%. Regarding the packaging materials, the aluminum bag prevented the deterioration of 14% of the curcuminoids for the powder exposed to UV radiation. Finally,... [more]
The Volume Stability of Alkali-Activated Electric Arc Furnace Ladle Slag Mortar and Its Performance at High Temperatures
Tung-Hsuan Lu, Ying-Liang Chen, Hong-Paul Wang, Juu-En Chang.
February 21, 2023 (v1)
Keywords: alkali-activated slag, electric arc furnace ladle slag, high temperature performance
In this study, the engineering properties of Ordinary Portland Cement (OPC) and alkali-activated slag (AAS) mortar with electric arc furnace ladle slag (EAFLS) were investigated to reveal the effects of EAFLS on the expansion of cementitious mortars. Additionally, the effects of these two types of mortar were explored based on their compressive strength, especially at high temperatures. EAFLS in OPC mortars significantly reduced the compressive strength and caused serious soundness problems in the mortars after autoclaving due to the presence of free-CaO and free-MgO in the EAFLS slag. On the other hand, the AAS mortars produced with EAFLS had compressive strength comparable to ordinary OPC mortars and maintained soundness after autoclaving. During a 550 °C heat treatment, the OPC mortar cracked and lost residual strength, but the AAS mortar retained more than 90% of its residual strength. Even after an 800 °C heat treatment, the AAS mortar maintained 14% of its residual strength (abou... [more]
A Techno-Economic Assessment of Fischer−Tropsch Fuels Based on Syngas from Co-Electrolysis
Ralf Peters, Nils Wegener, Remzi Can Samsun, Felix Schorn, Julia Riese, Marcus Grünewald, Detlef Stolten.
February 21, 2023 (v1)
Keywords: co-electrolysis, CO2 electrolysis, electrofuels, power-to-fuel, power-to-liquid, solid oxide electrolysis, synthetic diesel, synthetic kerosene, water electrolysis
As a part of the worldwide efforts to substantially reduce CO2 emissions, power-to-fuel technologies offer a promising path to make the transport sector CO2-free, complementing the electrification of vehicles. This study focused on the coupling of Fischer−Tropsch synthesis for the production of synthetic diesel and kerosene with a high-temperature electrolysis unit. For this purpose, a process model was set up consisting of several modules including a high-temperature co-electrolyzer and a steam electrolyzer, both of which were based on solid oxide electrolysis cell technology, Fischer−Tropsch synthesis, a hydrocracker, and a carrier steam distillation. The integration of the fuel synthesis reduced the electrical energy demand of the co-electrolysis process by more than 20%. The results from the process simulations indicated a power-to-fuel efficiency that varied between 46% and 67%, with a decisive share of the energy consumption of the co-electrolysis process within the energy balanc... [more]
SMEs in Automotive Supply Chains: A Survey on Six Sigma Performance Perceptions of Czech Supply Chain Members
Marcel Rolf Pfeifer.
February 21, 2023 (v1)
Keywords: automotive, six sigma, six sigma performance, SME, supplier development, Supply Chain
Six sigma is understood as a technique for the continuous improvement in process quality; however, it has been rarely scientifically analysed in small- and medium-sized enterprises (SMEs). SMEs representthe vast majority of enterprises throughout economies and contribute to automotive supply chains in various tier ranks. As SMEs are known to lack resources and skills while focusing on short-term benefits rather than on long-term gradual improvements, the aim of of this paper is to analyse the perception of six sigma process capabilities in automotive supply chains assuming differences in company size, supply chain rank and six sigma duration. This was tested with Fisher’s exact test. Companies with less than 1000 employees, subsuppliers and companies with a six sigma implementation in the last 3 years struggled to meet six sigma principles, suggesting that mainly small companies inhibit a risk for the supply chain. These findings contribute to the existing theoretical body of knowledge... [more]
A Multi-Physic Modelling Insight into the Differences between Microwave and Conventional Heating for the Synthesis of TiO2 Nanoparticles
Giulia Poppi, Elena Colombini, Diego Salvatori, Alessio Balestri, Giovanni Baldi, Cristina Leonelli, Paolo Veronesi.
February 21, 2023 (v1)
Subject: Materials
Keywords: conventional heating, heating rate, microwave heating, multi-physics numerical simulation, nanoparticles, temperature profile, TiO2 synthesis
Microwave-assisted synthesis of nanoparticles usually leads to a smaller and more uniformly distributed particle size compared to conventional heating (e.g., oil bath). Numerical simulation can help to obtain a better insight into the process in terms of temperature distribution or to evidence existing different temperature profiles and heating rates between the two techniques. In this paper multi-physics numerical simulation is used to investigate the continuous flow synthesis of titanium oxide nanoparticles starting from alkoxide precursors. Temperature-dependent permittivity of reactants has been measured, including the effects of permanence at the maximum synthesis temperature. A temperature homogeneity index has been defined to compare microwave and conventional heating. Results show that when using microwave heating at 2450 MHz, in the investigated conditions, a much higher temperature homogeneity of the reactants is reached. Moreover, reactants experience different heating rates... [more]
Material Removal Optimization Strategy of 3D Block Cutting Based on Geometric Computation Method
Hui Shao, Qimeng Liu, Zhiwei Gao.
February 21, 2023 (v1)
Subject: Materials
Keywords: average material removal rate (AMRR), block cutting, convex polygon (CPG), convex polyhedron (CPH), data reconstruction, path optimization
During the material removal stage in stone rough processing, milling type has been widely explored, which, however, may cause time and material consumption, as well as substantial stress for the environment. To improve the material removal rate and waste reuse rate in the rough processing stage for three-dimensional stone products with a special shape, in this paper, circular saw disc cutting is explored to cut a convex polyhedron out of a blank box, which approaches a target product. Unlike milling optimization, this problem cannot be well solved by mathematical methods, which have to be solved by geometrical methods instead. An automatic block cutting strategy is proposed intuitively by considering a series of geometrical optimization approaches for the first time. To obtain a big removal block, constructing cutting planes based on convex vertices is uniquely proposed. Specifically, the removal vertices (the maximum thickness of material removal) are searched based on the octree algo... [more]
Valuation of Climate Performance of a Low-Tech Greenhouse in Costa Rica
Adriana Rojas-Rishor, Jorge Flores-Velazquez, Edwin Villagran, Cruz Ernesto Aguilar-Rodríguez.
February 21, 2023 (v1)
Subject: Environment
Keywords: landsloping greenhouse, relative humidity, thermal difference, tomato and pepper crop
The expansion of protected agriculture has technological, climatic, and topographic limitations. The agricultural regions of Costa Rica use the greenhouse concept and adapt it to its conditions. The objective of this work was to describe the variation in temperature and humidity in a greenhouse ventilated passively and on land with a more than 45% slope. To evaluate the environment inside the greenhouse, temperature and humidity variations were measured with a weather station installed outside of the greenhouse to measure the external environment. Inside the greenhouse, 17 sensors were placed to measure the temperature (T) and relative humidity (RH). During data recording inside the greenhouse, tomato crops were in the fruit formation stage, and pepper was less than one week old. Six scenarios were tested to determine the air temperature and humidity dynamic under different climatic conditions. An evaluation of the greenhouse environment was carried out employing an analysis of varianc... [more]
Characterization of Stressing Conditions in a High Energy Ball Mill by Discrete Element Simulations
Christine Friederike Burmeister, Moritz Hofer, Palanivel Molaiyan, Peter Michalowski, Arno Kwade.
February 21, 2023 (v1)
Keywords: discrete element method, high energy ball mill, stressing model, sulfide solid electrolyte
The synthesis of sulfide solid electrolytes in ball mills by mechanochemical routes not only is efficient but also can enable the upscaling of material synthesis as required for the commercialization of solid-state battery materials. On a laboratory scale, the Emax high energy ball mill accounts for high stresses and power densities, as well as for temperature control, to prevent damage to the material and equipment even for long process times. To overcome the merely phenomenological treatment, we characterized the milling process in an Emax by DEM simulations, using the sulfide solid electrolyte LPS as a model material for the calibration of input parameters to the DEM, and compared it to a planetary ball mill for a selected parameter set. We derived mechanistic model equations for the stressing conditions depending on the operation parameters of rotational speed, media size and filling ratio. The stressing conditions are of importance as they determine the outcome of the mechanochemi... [more]
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