Diego Acosta
Universidad EAFIT, Process Engineering, Faculty Member
Research Interests:
Research Interests:
Research Interests:
Research Interests:
En este estudio, Se investigan las propiedades y comportamientos reológicos de mezclas entre bentonita y cera de parafina, utilizadas en la elaboración de la arcilla industrial de prototipado EAFIT. Para ello, se prepararon diversas... more
En este estudio, Se investigan las propiedades y comportamientos reológicos de mezclas entre bentonita y cera de parafina, utilizadas en la elaboración de la arcilla industrial de prototipado EAFIT. Para ello, se prepararon diversas formulaciones de bentonita y parafina. Se utilizaron diferentes proporciones de material para asegurar una fase homogénea. Las propiedades reológicas de las formulaciones resultantes fueron caracterizadas por un reómetro rotacional. Este artículo presenta la caracterización reológica de mezclas de cera de parafina y bentonita con el fin de obtener información para mejorar el proceso de extrusión de la arcilla industrial de prototipado desarrollada en la universidad EAFIT.In this study, rheological properties and behaviors of bentonite and paraffin wax blends used in the elaboration of a prototyping clay were investigated. For this purpose, various bentonite and paraffin formulations were prepared. 3 different material proportions were used to ensure a homogeneous phase. The rheological properties of the resulting formulations were characterized by a rotational rheometer. This paper presents the rheological characterization of paraffin wax and bentonite blends in order to obtain some insights to upscale the extrusion process of the prototyping industrial clay developed in EAFIT university
Research Interests:
Research Interests:
The automotive design process and the materials in the automotive industry in recent years has caused great interest to the industrial and academic sector. In this study was to evaluate the effect of the amount of bentonite on the thermal... more
The automotive design process and the materials in the automotive industry in recent years has caused great interest to the industrial and academic sector. In this study was to evaluate the effect of the amount of bentonite on the thermal and rheological properties of the compound bentonite / paraffin wax. Two bentonite ratios were used: paraffin wax (40:60 and 30:70). The paraffin was characterized by Fourier transform infrared spectroscopy (FTIR), the bentonite was characterized by means of x-ray diffraction (XRD), thermogravimetric analysis (TGA), X-ray fluorescence (XRF). The bentonite/paraffine wax composite was characterized by differential-scanning calorimetry (DSC) and rheology. The sample that contains a higher amount of bentonite shows a lower latent heat, and this could cause a greater heat transfer. Finally, the sample that has a lower amount of bentonite evidenced a lower viscosity, and it could be related to a lower interaction between the particles. The sample S1 due ...
Research Interests:
The characterization and control of plasma-assisted processes, has become increasingly urgent to adapt this kind technology to industrial contexts. This work presents the design and construction of a cold plasma characterization system by... more
The characterization and control of plasma-assisted processes, has become increasingly urgent to adapt this kind technology to industrial contexts. This work presents the design and construction of a cold plasma characterization system by electrostatic means (Langmuir probe), based on concepts of plasma physics and tools of engineering, design of experiments and conceptual design. The result of this work is a functional prototype probe and some measurements on the reactor
Research Interests:
All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
UMI, ProQuest ® Dissertations & Theses. The world's most comprehensive collection of dissertations and theses. Learn more... ProQuest, Manganese tetraoxide based polyalkenoate cements. by Acosta, Diego A., PhD, THE UNIVERSITY OF... more
UMI, ProQuest ® Dissertations & Theses. The world's most comprehensive collection of dissertations and theses. Learn more... ProQuest, Manganese tetraoxide based polyalkenoate cements. by Acosta, Diego A., PhD, THE UNIVERSITY OF OKLAHOMA, 2006, 0 pages; 3234987 ...
Research Interests:
Research Interests:
Purpose – Curve fitting from unordered noisy point samples is needed for surface reconstruction in many applications. In the literature, several approaches have been proposed to solve this problem. However, previous works lack formal... more
Purpose – Curve fitting from unordered noisy point samples is needed for surface reconstruction in many applications. In the literature, several approaches have been proposed to solve this problem. However, previous works lack formal characterization of the curve fitting problem and assessment on the effect of several parameters (i.e. scalars that remain constant in the optimization problem), such as control points number (m), curve degree (b), knot vector composition (U), norm degree (k), and point sample size (r) on the optimized curve reconstruction measured by a penalty function (f). The paper aims to discuss these issues. Design/methodology/approach – A numerical sensitivity analysis of the effect of m, b, k and r on f and a characterization of the fitting procedure from the mathematical viewpoint are performed. Also, the spectral (frequency) analysis of the derivative of the angle of the fitted curve with respect to u as a means to detect spurious curls and peaks is explored. ...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Shape optimization in the context of technical design is the process by which mechanical demands (e.g. loads, stresses) govern a sequence of piece instances, which satisfy the demands, while at the same time evolving towards more... more
Shape optimization in the context of technical design is the process by which mechanical demands (e.g. loads, stresses) govern a sequence of piece instances, which satisfy the demands, while at the same time evolving towards more attractive geometric features (e.g. lighter, cheaper, etc.). The SIMP (Solid Isotropic Material with Penalization) strategy seeks a redistribution of local densities of a part in order to stand stress / strain demands. Neighborhoods (e.g. voxels) whose density drifts to lower values are considered superfluous and removed, leading to an optimization of the part shape. This manuscript presents a study on how the parameters governing the voxel pruning affect the convergence speed and performance of the attained shape. A stronger penalization factor establishes the criteria by which thin voxels are considered void. In addition, ahe the filter discourages punctured, chessboard pattern regions. The SIMP algorithm produces a forecasted density map on the whole pie...
Research Interests:
All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
This article presents an industrial application case of geometric constraint graphs, whose nodes are statistically optimal instances of manufacturing or design features and whose edges are usual geometric relations used in tolerance... more
This article presents an industrial application case of geometric constraint graphs, whose nodes are statistically optimal instances of manufacturing or design features and whose edges are usual geometric relations used in tolerance applications -- The features might be virtual ones -- As a consequence, they may lie beyond the piece’s extents -- The geometric constraint graph may have cyclic topology -- Contrary to deterministic geometric constraint graphs, tolerance constraint graphs admit numerical slacks, due to their stochastic nature -- The methodology has been applied in industrial scenarios, showing superiority to traditional material features for the assessment of tolerances
Research Interests:
Compliant mechanisms are an instance of mechanical devices designed to transfer or transmit motion, force, or energy from specified input ports to output ports by elastic deformation of at least one of its members -- The main advantage of... more
Compliant mechanisms are an instance of mechanical devices designed to transfer or transmit motion, force, or energy from specified input ports to output ports by elastic deformation of at least one of its members -- The main advantage of compliant mechanisms with respect to traditional rigid-link mechanism is that fewer parts, fewer assembly process and no lubrication are required -- The HexFlex is a parallel compliant mechanism for nano-manipulating that allows six degrees of freedom of its moving stage -- This mechanism was designed for high precision an repeatability -- This article presents a methodology to model compliant mechanisms behavior under quasi-static conditions using computer experiments, reducing costs of experimentation of product development -- The methodology is used to establish a mathematical model that relates the actuator forces at the input ports with the position and orientation the end-effector stage of the Hexflex -- This mathematical model has direct app...
Research Interests:
In the context of lattice manufacturing, the problem of mechanical and structural characterization of large lattice domains is relevant. Lattice materials are used in engineering (e.g. in energy absorption and heat conduction) and... more
In the context of lattice manufacturing, the problem of mechanical and structural characterization of large lattice domains is relevant. Lattice materials are used in engineering (e.g. in energy absorption and heat conduction) and biomedical (e.g. bone implants and artificial tissues) applications. However, the numerical simulation of large lattice domains is limited by its complicated geometry, which hinders the meshing stage and produces intractable finite element meshes. The existing efforts to simulate large lattice domains are based on the generation of simplified homogeneous domains equipped with material properties that approximate the behavior of the lattice domain equipped with the bulk material. Using this approach, one can estimate the displacements field over the lattice domain using a lighter mesh and a cheaper simulation. However, since stresses are influenced by geometrical conditions, the stresses of the simplified domain do not match the stresses of the lattice doma...
Lattice-based workpieces contain patterned repetition of individuals of a basic topology (Schwarz, ortho-walls, gyroid, etc.) with each individual having distinct geometric grading. In the context of the design, analysis and manufacturing... more
Lattice-based workpieces contain patterned repetition of individuals of a basic topology (Schwarz, ortho-walls, gyroid, etc.) with each individual having distinct geometric grading. In the context of the design, analysis and manufacturing of lattice workpieces, the problem of rapidly assessing the mechanical behavior of large domains is relevant for pre-evaluation of designs. In this realm, two approaches can be identified: (1) numerical simulations which usually bring accuracy but limit the size of the domains that can be studied due to intractable data sizes, and (2) material homogenization strategies that sacrifice precision to favor efficiency and allow for simulations of large domains. Material homogenization synthesizes diluted material properties in a lattice, according to the volume occupancy factor of such a lattice. Preliminary publications show that material homogenization is reasonable in predicting displacements, but is not in predicting stresses (highly sensitive to lo...
La presente recherche compare les differences dans le desencrage par flottation des papiers de bureau tries imprimes avec une encre a base d'eau et de toner, soit avec du dodecanoate de sodium ou de l'octanoate de sodium comme... more
La presente recherche compare les differences dans le desencrage par flottation des papiers de bureau tries imprimes avec une encre a base d'eau et de toner, soit avec du dodecanoate de sodium ou de l'octanoate de sodium comme surfactants, en conjonction avec du calcium. Pour l'encre de toner avec l'un ou l'autre surfactant agissant en l'absence d'ajout d'ions calcium, le nombre de points noirs a diminue moins que lorsque du calcium etait employe sans surf actants. Lorsqu'on utilise les surfactants avec du calcium, la diminution du nombre de points noirs est encore plus prononcee. L'encre a base d'eau a ete enlevee quantitativement pendant le desencrage par flottation. Les mesures de la repartition de la taille des particules, du nombre de points noirs et de la blancheur confirment que l'adsorption, et non la precipitation du surfactant, est le phenomene critique entrainant l'amelioration de la flottation par ces additifs dans le d...
Research Interests:
In the domain of generation of wind turbine energy, it is central to correctly estimate the interactions among the various turbines in a wind turbine farm. The spatial super-position of turbine wind wakes determines the wind conditions... more
In the domain of generation of wind turbine energy, it is central to correctly estimate the interactions among the various turbines in a wind turbine farm. The spatial super-position of turbine wind wakes determines the wind conditions that each turbine in the farm is exposed to and its power output. The current state of the art represents the turbine wakes as a 2D real-valued polygonal trapezoid. The interactions among wakes imply Boolean operations among many trapezoids, producing an intractable fragmentation of the wake intersection and domain regions. The plan (2D) view of the terrain with this wake polygon fragmentation is then used to estimate the effective wind that each turbine receives. This calculation leads to cumbersome computation, which is even more impractical if 3D representations of the terrain, wakes and wind are needed. In response to these limitations, this manuscript presents a method in which the 2D turbine wakes are located on a terrain with holes and exclusio...
Evolutionary Structural Optimization (ESO) seeks to mimic the form in which nature designs shapes. This paper focuses on shape carving triggered by environmental stimuli. In this realm, existing algorithms delete under - stressed parts of... more
Evolutionary Structural Optimization (ESO) seeks to mimic the form in which nature designs shapes. This paper focuses on shape carving triggered by environmental stimuli. In this realm, existing algorithms delete under - stressed parts of a basic shape, until a reasonably efficient (under some criterion) shape emerges. In the present article, we state a generalization of such approaches in two forms: (1) We use a formalism that enables stimuli from different sources, in addition to stress ones (e.g. kinematic constraints, friction, abrasion). (2) We use metagraphs built on the Finite Element constraint graphs to eliminate the dependency of the evolution on the particular neighborhood chosen to be deleted in a given iteration. The proposed methodology emulates 2D landmark cases of ESO. Future work addresses the implementation of such stimuli type, the integration of our algorithm with evolutionary based techniques and the extension of the method to 3D shapes.
Grinding of finished cement is performed in a single stage, intergrinding materials with very different grindabilities. This intergrinding process has many different interactions among the different components of the finished cement. In a... more
Grinding of finished cement is performed in a single stage, intergrinding materials with very different grindabilities. This intergrinding process has many different interactions among the different components of the finished cement. In a context of developing more sustainable and less energy intensive processes, it is important to understand the contribution of the individual components of cement mixtures to the overall energy consumption. A better understanding of the changes in resistance to grinding as a function of the mixture composition can aid to improve process throughput and efficiency. Therefore, understanding the relationship of the resistance to grinding of the cement components to the overall resistance when intergrinding is essential to optimize and reduce the energy consumption of these processes. Herein, we evaluate experimentally the interactions among clinker, limestone and gypsum during the final grinding stage in Portland cement production. We present a simple, yet rigorous, method that enables the determination of the individual grinding contributions to the intergrinding process. By using Rittinger’s KR parameter, our method is able to predict the contribution of the individual components even for blends with particle sizes below 100 µm. We used this model as the input for a nonlinear optimization that allowed for the identification of an optimum region of composition for Portland cement pastes, including restrictions to the heat of hydration and compressive strength development. The developed models can be easily adapted to aid in the formulation of cement blends with different characteristics to the raw materials used in this study.
Developing more energy-efficient and environmentally friendly transportation technologies, that can enable to use significantly less petroleum and to reduce regulated emissions while meeting or exceeding drivers’ performance expectations,... more
Developing more energy-efficient and environmentally friendly transportation technologies, that can enable to use significantly less petroleum and to reduce regulated emissions while meeting or exceeding drivers’ performance expectations, has always been one of the main challenges in automotive technology. Therefore, based on an experimental dataset, metamodels were generated using design of computer experiments and central composite design technique in order to accurately predict carbon monoxide (CO), oxides of nitrogen ( $$\text {NO}_{x}$$ NO x ), hydrocarbon (HC) and carbon dioxide ( $$\text {CO}_{2}$$ CO 2 ) emissions, mean effective pressure and exergy destruction due to heat transfer and combustion process. Combustion metamodels was evaluated varying air–fuel ratio, ignition timing [( $$^{\circ }$$ ∘ CAD) Crank Angle Degrees], compression ratio, and combustion duration ( $$^{\circ }$$ ∘ ) on the performance of a Spark Ignition (SI) engine at constant speed of 750 rpm. Because SI gasoline engines always encounter the decreased thermal efficiency and increased toxic emissions at idle (Jurgen in Automotive electronics handbook, McGraw-Hill, New York, 1995). The Akaike information criterion was applied to automatically select the best metamodel for each case.
Research Interests:
A Fenton like advanced oxidation process (AOP) employing scrap zerovalent iron (SZVI) and hydrogen peroxide (H2O2) was studied for industrial textile wastewater treatment from a textile manufacturing plant located at Medellín, Colombia... more
A Fenton like advanced oxidation process (AOP) employing scrap zerovalent iron (SZVI) and hydrogen peroxide (H2O2) was studied for industrial textile wastewater treatment from a textile manufacturing plant located at Medellín, Colombia (South America). The wastewater effluent studied contains a mixture of organic compounds resistant to conventional treatments. The effect of initial pH and SZVI concentration and H2O2 concentration were studied by a response surface methodology (RSM) Box-Behnken design of experiment (BBD). The combined SZVI/H2O2 process led to reductions of 95% color, 76% of chemical oxygen demand (COD) and 71% of total organic carbon (TOC) at optimal operating conditions of pH = 3, SZVI = 2000 mg/L and [H2O2] = 24.5 mM. Molecular weight distribution measurement (MWD), ultraviolet-visible (UV-Vis) spectroscopy, HPLC, biodegradability and toxicity were used to characterize the pollutants after the treatment process finding that the resulting effluent was polluted mostly by low molecular weight carboxylic acids. A remarkable biodegradability enhancement of the effluent was evidenced by a BOD5/COD ratio increase from 0.22 to 0.4; also, the SZVI/H2O2 process successfully reduced the toxicity from 60% to 20% of dead A. Salina crustaceans.
Research Interests:
This work develops a systematic methodology able to identify the desired work points, the metamodels were evaluated varying air–fuel ratio, ignition timing, compression ratio, and combustion duration using design of computer experiments... more
This work develops a systematic methodology able to identify the desired work points, the metamodels were evaluated varying air–fuel ratio, ignition timing, compression ratio, and combustion duration using design of computer experiments and RSM. It provide the possibility to determine optimal control parameters, according to selected objectives and operating constraints. This methodology is able to automatically identify the optimal engine calibration with less computational effort. Only in this way, the reliability of an integrated metamodel/optimizer approach can be included in a general-purpose that is to identify the engine calibration that minimizes motor vehicle emissions according to European emission standards (European Union in Off J Eur Union 50, 2007). As long as it improves mean effective pressure and reduces exergy destruction due to heat transfer and combustion process. Since, in internal combustion engines, more than 30–40 % of fuel energy wastes through the exhaust and just 12–25 % of the fuel energy converts to useful work. So, researchers are motivated to recover the heat from the waste sources in engines using the ways which not only reduce the demand of fossil fuels, but also reduce the harmful greenhouse gases and help to energy saving (Hatami et al. in Neural Comput Appl 25(7–8):2079–2090, 2014). The advantages of this contribution include the ability to study a wide range of parametric space and to independently evaluate physical and chemical processes, and detailed in-cylinder information, which is normally not available or is inaccessible in experiments. The uncertainty of the information in this unexplored design region can be quantified. Finally, the problem of optimizing involves three optimization fronts, energetic, economic and ecological (Chica and Torres in Int J Interact Des Manuf 12(1):355–392, 2018).
Research Interests:
Abstract The challenges that a shape or design stands are central in its evolution. In the particular domain of stress/strain challenges, existing approaches eliminate under-demanded neighborhoods from the shape, thus producing the... more
Abstract The challenges that a shape or design stands are central in its evolution. In the particular domain of stress/strain challenges, existing approaches eliminate under-demanded neighborhoods from the shape, thus producing the evolution. This strategy alone incorrectly (a) conserves disconnected parts of the shape and (b) eliminates neighborhoods which are essential to maintain the boundary conditions (supports, loads). The existing analyses preventing (a) and (b) are conducted in an ad-hoc manner, by using graph connectivity. This manuscript presents the implementation of a meta-graph methodology, which systematically lumps together finite element subsets of the current shape. By considering this meta-graph connectivity, the method impedes situations (a) and (b), while maintaining the pruning of under-demanded neighborhoods. Research opportunities are open in the application of this methodology with other types of demand on the shape (e.g., friction, temperature, drag, and abrasion).
Research Interests:
Purpose Mesh Parameterization is central to reverse engineering, tool path planning, etc. This work synthesizes parameterizations with un-constrained borders, overall minimum angle plus area distortion. This study aims to present an... more
Purpose Mesh Parameterization is central to reverse engineering, tool path planning, etc. This work synthesizes parameterizations with un-constrained borders, overall minimum angle plus area distortion. This study aims to present an assessment of the sensitivity of the minimized distortion with respect to weighed area and angle distortions. Design/methodology/approach A Mesh Parameterization which does not constrain borders is implemented by performing: isometry maps for each triangle to the plane Z = 0; an affine transform within the plane Z = 0 to glue the triangles back together; and a Levenberg–Marquardt minimization algorithm of a nonlinear F penalty function that modifies the parameters of the first two transformations to discourage triangle flips, angle or area distortions. F is a convex weighed combination of area distortion (weight: α with 0 ≤ α ≤ 1) and angle distortion (weight: 1 − α). Findings The present study parameterization algorithm has linear complexity [𝒪(n), n = ...
Research Interests:
Abstract Waterborne adhesives for rubber to metal bonding have been available since 1990. However, published information about their formulation has been limited, as proprietary restrictions are exercised by companies. As a consequence,... more
Abstract Waterborne adhesives for rubber to metal bonding have been available since 1990. However, published information about their formulation has been limited, as proprietary restrictions are exercised by companies. As a consequence, the way these adhesives interact with substrates has not been studied extensively. With the aim of investigating the effect the components of a waterborne adhesive have on rubber to metal bonding, fractional factorial and surface response methodologies of design of experiments were employed in this study. Twenty six formulations were prepared with a polychloroprene latex as the adhesive polymer. Viscosity, wettability and non-volatile solids content were measured with each liquid adhesive, while the mechanical strength was evaluated by applying a tensile mechanical stress over cured solid adhesive films. Adhesion properties were evaluated by using a single lap-shear test on metal to metal joints and a pull-out test on rubber to metal joints. The results showed that the components with the largest relative influence on cohesive and adhesives forces were tackifier resin, silicon dioxide and polychloroprene latex type. In order to better understand the contributions of these variables, mathematical models correlating them with the response variables were obtained. This study is valuable in explaining how, through statistical methods, a waterborne adhesive for rubber to metal bonding can be formulated with a reasonably low number of experiments.
Research Interests:
Numerical optimization solve problems efficiently where such efficiency is focused on the speed with which the optimal $${{\varvec{x}}}^{{*}}$$x∗ is achieved, is open line of research and strong work in the scientific community in order... more
Numerical optimization solve problems efficiently where such efficiency is focused on the speed with which the optimal $${{\varvec{x}}}^{{*}}$$x∗ is achieved, is open line of research and strong work in the scientific community in order to achieve control systems in dynamic processes with response times of the order of milliseconds. A clear example of this, is the implementation of optimal controller’s combustion engines. For subsequent approach to the design and implementation of nonlinear model predictive control controllers, it has made a comparison of yields algorithms quadratic programming by active set with linearization restrictions, and sequential quadratic programming with single shooting technique to solve quadratic optimization problem formulation referred to a dynamic internal combustion engine of spark ignition, in embedded systems with real-time processing.
Research Interests:
A mathematical model of emissions was developed in a Twingo D7F engine. The effects of variations in compression ratio, fuel/air equivalence ratio, spark advanced and combustion duration under pollutant emissions were studied. Analysis... more
A mathematical model of emissions was developed in a Twingo D7F engine. The effects of variations in compression ratio, fuel/air equivalence ratio, spark advanced and combustion duration under pollutant emissions were studied. Analysis and data collection were performed in an engine bank using a data acquisition system integrated to an Interactive Engineering Environment. A control strategy was implemented to guarantee emissions reduction.
Research Interests:
The end result of this research is an application created using freely available tools applied to a case scenario to perform review meetings by different specialists in real time. Initial tests on the system have been made with Civil... more
The end result of this research is an application created using freely available tools applied to a case scenario to perform review meetings by different specialists in real time. Initial tests on the system have been made with Civil Engineering students showing that this virtual reality tool eases the burden of performing engineering drawings reviews that are traditionally done at the same geographical space.
The characterization and control of plasma-assisted processes, has become increasingly urgent to adapt this kind technology to industrial contexts. This work presents the design and construction of a cold plasma characterization system by... more
The characterization and control of plasma-assisted processes, has become increasingly urgent to adapt this kind technology to industrial contexts. This work presents the design and construction of a cold plasma characterization system by eleEctrostatic means (Langmuir probe), based on concepts of plasma physics and tools of engineering, design of experiments and conceptual design. The result of this work is a functional prototype probe and some measurements on the reactor.
Research Interests:
ABSTRACT Stand-alone and networked surgical virtual reality based simulators have been proposed as means to train surgical skills with or without a supervisor nearby the student or trainee. However, surgical skills teaching in medicine... more
ABSTRACT Stand-alone and networked surgical virtual reality based simulators have been proposed as means to train surgical skills with or without a supervisor nearby the student or trainee. However, surgical skills teaching in medicine schools and hospitals is changing, requiring the development of new tools to focus on: (i) importance of mentors role, (ii) teamwork skills and (iii) remote training support. For these reasons a surgical simulator should not only allow the training involving a student and an instructor that are located remotely, but also the collaborative training session involving a group of several students adopting different medical roles during the training session. Collaborative Networked Virtual Surgical Simulators (CNVSS) allow collaborative training of surgical procedures where remotely located users with different surgical roles can take part in a training session. Several works have addressed the issues related to the development of CNVSS using various strategies. To the best of our knowledge no one has focused on handling heterogeneity in collaborative surgical virtual environments. Handling heterogeneity in this type of collaborative sessions is important because not all remotely located users have homogeneous Internet connections, nor the same interaction devices and displays, nor the same computational resources, among other factors. Additionally, if heterogeneity is not handled properly, it will have an adverse impact on the performance of each user during the collaborative session. In this paper we describe the development of an adaptive architecture with the purpose of implementing a context-aware model for collaborative virtual surgical simulation in order to handle the heterogeneity involved in the collaboration session
Research Interests:
A mathematical and numerical model of flow and combustion process for spark ignition engines is developed using the principles of the first and second law of thermodynamic. Availability (exergy) analysis is applied to cylinder of a spark... more
A mathematical and numerical model of flow and combustion process for spark ignition engines is developed using the principles of the first and second law of thermodynamic. Availability (exergy) analysis is applied to cylinder of a spark ignition engine during the combustion process using a two-zone combustion model. Special attention is given to identification and quantification of irreversibility of combustion process and energy available basing on the isooctane fuel explosion. To predict emissions generation (greenhouse gases) a skeletal mechanism including 32 species and 61 reactions was developed and tested for different engine operations and exergy destructions.
Stand-alone and networked surgical simulators based on virtual reality have been proposed as a means to train surgeons in specific surgical skills with or without expert guidance and supervision. However, a surgical operation usually... more
Stand-alone and networked surgical simulators based on virtual reality have been proposed as a means to train surgeons in specific surgical skills with or without expert guidance and supervision. However, a surgical operation usually involves a group of medical practitioners who cooperate as team members. To this end, CNVSS have been proposed for the collaborative training of surgical procedures in which users with different surgical roles can take part in the training session. To be successful, these simulators should guarantee synchronicity, which requires (1) consistent viewing of the surgical scene and (2) a quick response time. These two variables are affected by factors such as users' machine capabilities and network conditions. As far as we know, the impact of these factors on the performance of CNVSS has not been evaluated. In this paper, we describe the development of CNVSS and a statistical factorial design of experiments (DOE) to determine the most important factors a...
Research Interests:
Curve reconstruction from noisy point samples is needed for surface reconstruction in many applications (eg medical imaging, reverse engineering, etc.). Because of the sampling noise, curve reconstruction is conducted by minimizing the... more
Curve reconstruction from noisy point samples is needed for surface reconstruction in many applications (eg medical imaging, reverse engineering, etc.). Because of the sampling noise, curve reconstruction is conducted by minimizing the fitting ...
Compliant mechanisms are an instance of mechanical devices designed to transfer or transmit motion, force, or energy from specified input ports to output ports by elastic deformation of at least one of its members. The main advantage of... more
Compliant mechanisms are an instance of mechanical devices designed to transfer or transmit motion, force, or energy from specified input ports to output ports by elastic deformation of at least one of its members. The main advantage of compliant mechanisms with respect to ...
Research Interests:
Research Interests:
Fitting of analytic forms to point or triangle sets is central to computer-aided design, manufacturing, reverse engineering, dimensional control, etc. The existing approaches for this fitting assume an input of statistically strong point... more
Fitting of analytic forms to point or triangle sets is central to computer-aided design, manufacturing, reverse engineering, dimensional control, etc. The existing approaches for this fitting assume an input of statistically strong point or triangle sets. In contrast, this manuscript reports the design (and industrial application) of fitting algorithms whose inputs are specifically poor triangular meshes. The analytic forms currently addressed are planes, cones, cylinders and spheres. Our algorithm also extracts the support submesh responsible for the analytic primitive. We implement spatial hashing and boundary representation for a preprocessing sequence. When the submesh supporting the analytic form holds strict C0-continuity at its border, submesh extraction is independent of fitting, and our algorithm is a real-time one. Otherwise, segmentation and fitting are codependent and our algorithm, albeit correct in the analytic form identification, cannot perform in real-time.
Research Interests:
A combined electrocoagulation (EC) and electrochemical oxidation (EO) industrial textile wastewater treatment potential is evaluated in this work. A fractional factorial design of experiment showed that EC current density, followed by pH,... more
A combined electrocoagulation (EC) and electrochemical oxidation (EO) industrial textile wastewater treatment potential is evaluated in this work. A fractional factorial design of experiment showed that EC current density, followed by pH, were the most significant factors. Conductivity and number of electrooxidation cells did not affect chemical oxygen demand degradation (DCOD). Aluminum and iron anodes performed similarly as sacrificial anodes. Current density, pH and conductivity were chosen for a Box–Behnken design of experiment to determine optimal conditions to achieve a high DCOD minimizing operating cost (OC). The optimum to achieve a 70% DCOD with an OC of USD 1.47/m3 was: pH of 4, a conductivity of 3.7 mS/cm and a current density of 4.1 mA/cm2. This study also shows the applicability of a combined EC/EO treatment process of a real complex industrial wastewater.
Research Interests:
Research Interests:
In depth map generation, the settings of the algorithm parameters to yield an accurate disparity estimation are usually chosen empirically or based on unplanned experiments. A systematic statistical approach including classical and... more
In depth map generation, the settings of the algorithm parameters to yield an accurate disparity estimation are usually chosen empirically or based on unplanned experiments. A systematic statistical approach including classical and exploratory data analyses on over 14000 images to measure the relative influence of the parameters allows their tuning based on the number of bad_pixels. Our approach is systematic in the sense that the heuristics used for parameter tuning are supported by formal statistical methods. The implemented methodology improves the performance of dense depth map algorithms. As a result of the statistical based tuning, the algorithm improves from 16.78% to 14.48% bad_pixels rising 7 spots as per the Middlebury Stereo Evaluation Ranking Table. The performance is measured based on the distance of the algorithm results vs. the Ground Truth by Middlebury. Future work aims to achieve the tuning by using significantly smaller data sets on fractional factorial and surface-response designs of experiments.