Development of an iterative learning controller for polymer based micro-stereolithography prototyping systems

Additive manufacturing has become increasingly popular for a wide range of applications in recent years. Micro-stereolithography (μSLA) is a popular method for obtaining polymer-based parts. Systems using the μSLA approach usually consist of a vertical positioning system, a light source and a container where the component is built gradually as the polymer is cured at the locations where the ultraviolet light is projected. It has been noted that the motion of the positioning system and the intensity of the light source is an important factor to achieve high level dimensional precision. In this paper a three dimensional error based learning scheme is presented to improve the time varying process parameters of the system so that the dimensional accuracy of the product is improved. A mathematical model of the curing process is used for developing the error based learning algorithm. The current process parameters as a function of time and the dimensional error obtained at each layer of the production are used for increasing the quality and precision of the same part in the next iteration. Our initial simulation results show significant improvements can be obtained in a few iterations if the correct learning parameters are used based on the target parts dimensional properties. © 2016 American Automatic Control Council (AACC)

Swappable distributed MIMO controller for a VCT engine

In the early days of computer control, only one centralized computer was responsible for executing the algorithms. Increasingly, computer control algorithms reside inside individual system components in a distributed fashion. Variable camshaft timing (VCT) is an appealing feature for automotive engines because it allows optimization of the cam timing over a wide range of operating conditions. In this paper, a method to distribute the discrete multiple-input mutiple-output controller for the VCT engine to improve the component swapping modularity of the VCT actuator and the EGO sensor components using network communications is presented. First, a discrete LQG controller is designed, and then this controller is distributed to the engine control unit, the VCT controller, and the EGO sensor controller in order to maximize the component swapping modularity of the system. A control oriented pre-optimization technique, which simplifies the optimization problem, and a candidate solution was devised to maximize component modularity. © 2006 IEEE

Combined component swapping modularity for a VCT engine controller

The use of bi-directional communication provides additional design freedom which can be used to maximize the swapping modularity of networked smart components. In this paper, application of a design method for combined swapping modularity of two or more system components is discussed. Development of measures for combined swapping modularity is important to be able to analyze more realistic engineering cases. The combined modularity problem is a more difficult problem compared to the individual component swapping modularity problem. First, two approaches (simultaneous and sequential) for combining component swapping modularity of two or more components are presented. Then these combined modularity approaches are used to design controllers which maximize the component-swapping modularity of the Variable Camshaft Timing (VCT) component (i.e. actuator and sensor) and the Exhaust Gas Oxygen (EGO) sensor for an internal combustion engine. Copyright © 2009 by ASME

Model-in-the-loop development for fuel cell vehicle

In this paper, the work on developing and validating a model-in-the-loop (MIL) simulation environment for a group of prototype fuel cell vehicles is presented. The MIL model consists of a vehicle plant model and an integrated vehicle system controller model. First, the vehicle simulation plant model is functionally validated with a simple vehicle system controller (VSC) model and then improved to satisfy the input output interface and fidelity requirements. The developed MIL system is then verified for basic functionality against the simple VSC controller model and shows uniform correlation results. It is further validated against vehicle dynamometer test data and demonstrates satisfactory consistency. A rapid model building approach which is suitable for model-based controller design process was also discussed. This approach enabled the developers to use model-to-code algorithms unlike many comparable simulation models. © 2011 AACC American Automatic Control Council

Effects of ultrasound on the performance improvement of wastewater microfiltration through a porous ceramic filter

Filtration under an ultrasonic field is a technique that is gaining importance in the wastewater treatment research field, not only due to its ability as a cleaning mechanism, but also as a filtration intensifier. The main objective of this research was the study of the influence of ultrasonic waves on the filtration of theoilfield wastewater (known as produced water) in order to increase the operation performance and filter medium regenerative effectiveness. A 0.016 m2 hollow cylindrical porous ceramic filter was submitted to the filtration of produced water by two mechanisms: conventional filtration under vacuum and filtration under theinfluence of ultrasonic waves. Experiments were carried out using synthetic produced water by analyzing the variables oil and grease content (O&G) and total suspended solids (TSS) for each filtration run. Backwashing of the filter medium with distilled water was also performed to evaluate the regeneration efficiency. During conventional filtration, permeate flux decreased gradually, becoming stable around 0.06 cm3.cm-2.s-1. Furthermore, in the filtration assisted by ultrasound, the permeate flux was around 0.15 cm3.cm-2.s-1. Therefore, ultrasonic waves provided an increase of about 150% in the permeate flux. Moreover, the sonication improved filter medium regeneration effectiveness, even under conditions of high TSS and O&G contents. Taking into consideration the very positive results associated with the application of ultrasonicwaves, this filtration technique is likely to become an important industrial process

Microalgae production and biofuel from microalgae [Mikroalg üretimi ve mikroalglerden biyoyakit eldesi]

Fossil fuel reserves which supplying a major portion of energy needs, are depleting rapidly, and its environmental damages increases day by day. Therefore, like all developed and developing countries, our country have focused on the use of renewable energy sources. Within this scope in the our country, it was aimed gain of renewable energy sources to economy, promotion of sustainable energy production, and protection of environmental. Recently, one of the growing importance of renewable energy sources is the biomass energy. As an biomass energy source, all vegetable and animal organic substances which the main components are comprising carbohydrate compounds can be used. In these energy sources, microalgae seem promising for biofuel production due to their many advantages such as they have high photosynthetic efficiency, high biomass production, and they grow quickly. From microalgae, by using biochemical methods electricity, ethanol, hydrogen, methane and biodiesel and thermochemical methods syngas, biochar, biodiesel and electricity can be produced. In this review article, isolation of microalgae, microalgal biomass production, the methods used to biomass harvesting, and the availability of microalgae as a source of raw materials for renewable biofuels were viewed

Adaptive neuro-fuzzy modeling of head loss in iron removal with rapid sand filtration

Breakthrough and terminal head loss are the main parameters that determine the performance of rapid sand filters. Carman-Kozeny and Ergun equations can be applied to estimate head loss, but can only be applied to clean filter beds. Elaborated models are needed to predict head loss in dirty filters. In this study, a neuro-fuzzy modeling approach was proposed to estimate head loss in dirty filters. Hydraulic loading rate, influent iron concentration, bed porosity, and operating time were selected as input variables. Various types of membership functions were tried. Two rule-base generation methods - subtractive clustering and grid partition - were used for a first-order, Sugeno-type inference system. Using 11 rules and the grid-partition method, an optimum rule base set was developed and the lowest root mean squared error (RMSE) was obtained. Tap and deionized waters were used to obtain testing RMSE values of 1.094 and 0.926, respectively. The fit between experimental results and model outputs was excellent, with the multiple correlation coefficient (R2) greater than 0.99. Based on these findings, the authors conclude that neurofuzzy modeling may successfully be used to predict filter head loss

Cost analysis of seawater desalination with reverse osmosis in Turkey

Economically usable water resources per capita are decreasing due to excessive population increase each year in Turkey. For this reason, new water resources should be found in the near future. The potential water resources are seawater or well water both of which need removal of salinity. The most promising treatment method for salinity is reverse osmosis. While reverse osmosis becomes widespread, the cost of the process will decrease. There is no detailed information about cost of seawater desalination in Turkey. In this study, a cost analysis of seawater desalination in Turkey was performed for reverse osmosis systems. The basic parameters of cost analysis such as capacity, recovery, membrane life, energy, chemical costs and flux were evaluated based on the effects on capital, operating and total production costs. © 2008

Fabrication of Polymer Micro Needles for Transdermal Drug Delivery System Using DLP Based Projection Stereo-lithography

Fabrication of micro needles, which reduce pain during insertion and lessen tissue injury, has recently attracted great interest. Different manufacturing systems have been utilized for the advancement of micro needles such as two-photon photo polymerization, bulk lithography, droplet-borne air blowing and injection molding [1]. This paper proposes a micro fabrication process for polymer micro needles, using DLP based projection-based stereo lithography that is capable of fabricating micro-needles using biocompatible polymers. The fabrication in the experimental setup is performed with continuous movement of the platform in the vertical direction hence good surface quality is obtained. The influence of polymerization time, light intensity of DLP projector and chemical composition of the resins on the production speed and the geometrical accuracy of the micro needles have been studied. The length and the tip diameter of the micro needle are shown to be controlled through these factors. The length and tip diameter of the fabricated micro needles were observed using SEM and optical microscope and measured to be around 520 μm and 40 μm, respectively. The results indicate that polymer micro needles with appropriate geometry can be fabricated using this technique. © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license

Treatment processes based on the molecular weight distribution of textile dyeing wastewater

Rinsing wastewater from dyeing and bleaching processes in a cotton dyeing facility has been separately characterized to evaluate the suitable treatment processes and reuse options. Alternative treatment processes were proposed based on molecular weight distribution (MWD), ultraviolet absorbance of 254 nm (UV254) and specific ultraviolet absorbance (SUVA). Rinsing wastewater samples were sequentially filtrated to determine the MWD of 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), dissolved organic carbon (DOC), total Keldahl nitrogen (TKN) and ammonium (NH4+). Bleaching rinsing wastewater had higher organic and nitrogen contents than dyeing rinsing wastewater and concentrations of pollutants decreased after each membrane filtration step. During the sequential filtration, BOD5/COD ratio in bleaching rinsing wastewater slightly decreased while it significantly increased in dyeing rinsing wastewater. SUVA values indicated that organic matters in the rinsing wastewaters have hydrophilic characteristics in all conditions. The evaluation of all experimental data indicates that combination of anaerobic treatment and NF membrane filtration could provide high quality water for reuse within the facility and discharge into receiving environments