Showing papers on "Process variable published in 2008"

Evaluation of a New Wireless Temperature Remote Interrogation System (TEMPRIS) to Measure Product Temperature During Freeze Drying

Abstract: The purpose of this research was to evaluate a new wireless and battery-free sensor technology for invasive product temperature measurement during freeze-drying. Product temperature is the most critical process parameter in a freeze-drying process, in particular during primary drying. The product temperature over time profile and a precise detection of the endpoint of ice sublimation is crucial for comparison of freeze-drying cycles. Traditionally, thermocouples are used in laboratory scale units whereas resistance thermal detectors are applied in production scale freeze-dryers to evaluate temperature profiles. However, both techniques show demerits with regard to temperature comparability and biased measurements relative to vials without sensors. A new generation of wireless temperature sensors (Temperature Remote Interrogation System, TEMPRIS) were used in this study to investigate for the first time their value when applied to freeze-drying processes. Measurement accuracy, capability of accurate endpoint detection and effect of positioning were delineated by using product runs with sucrose, mannitol and trehalose. Data were compared to measurements with 36-gauge thermocouples as well as to non-invasive temperature measurement from Manometric Temperature Measurements. The results show that the TEMPRIS temperature profiles were in excellent agreement to thermocouple data when sensors were placed center bottom in a vial. In addition, TEMPRIS sensors revealed more reliable temperature profiles and endpoint indications relative to thermocouple data when vials in edge position were monitored. The results of this study suggest that TEMPRIS may become a valuable tool for cycle development, scale-up and routine manufacturing in the future.

Apparatus and method for visualization of control techniques in a process control system

Abstract: Various graphical displays used for visualization of control techniques in a process control system can be provided to an operator. For example, a graphical display (200) could include (i) an image (218, 224) associated with at least a portion of a process and (ii) one or more icons (230a-230f) identifying one or more process variables associated with at least the portion of the process. Selection of an icon could present the operator with a faceplate (350, 350a-350c) containing information associated with at least one of the process variables. Another graphical display (1200) could include (i) a focal variable symbol (1204) identifying a focal process variable and (ii) one or more additional variable symbols (1206) identifying one or more additional process variables associated with the focal process variable. Gains associated with the additional process variables could be identified in the display. Yet another graphical display (2600) could be used to remotely invoke and control applications executing in a process control system (100).

Application of Taguchi philosophy for parametric optimization of bead geometry and HAZ width in submerged arc welding using a mixture of fresh flux and fused flux

Abstract: Taguchi philosophy has been applied for obtaining optimal parametric combinations to achieve desired weld bead geometry and dimensions related to the heat-affected zone (HAZ), such as HAZ width in the present case, in submerged arc welding. The philosophy and methodology proposed by Dr. Genichi Taguchi can be used for continuous improvement in products that are produced by submerged arc welding. This approach highlights the causes of poor quality, which can be eliminated by self-adjustment among the values of the process variables if they tend to change during the process. Depending on functional requirements of the welded joint, an acceptable weldment should confirm maximum penetration, minimum reinforcement, minimum bead width, minimum HAZ width, minimum bead volume, etc. to suit its area of application. Hence, there exists an increasing demand to evaluate an optimal parameter setting that would fetch the desired yield. This could be achieved by optimization of welding variables. Based on Taguchi’s approach, the present study has been aimed at integrating statistical techniques into the engineering process. Taguchi’s L9 (3**3) orthogonal array design has been adopted and experiments have been accordingly conducted with three different levels of conventional process parameters using welding current and flux basicity index to obtain bead-on-plate weld on mild steel plates. Features of bead geometry and HAZ in terms of bead width, reinforcement, depth of penetration and HAZ width have been measured for each experimental run. The slag, generated during welding, has been consumed in further runs by mixing it with fresh unmelted flux. The percentage of slag in the mixture of fused flux (slag) and fresh flux has been defined as slag-mix%. Welding has been performed by using varying slag-mix%, treated as another process variable, in order to obtain the optimum amount of slag-mix that can be used without any alarming adverse effect on features of bead geometry and HAZ. This would lead to ‘waste to wealth’.

Pulsed Nd:YAG laser turning of micro-groove on aluminum oxide ceramic (Al2O3)

Abstract: The present study investigates the relationship of processes parameters of pulsed Nd:YAG laser-turning operation for production of micro-groove on cylindrical workpiece of ceramic material. A microprocessor-based work holding device has been developed to provide the rotational motion of cylindrical work pieces for micro-turning operation. Laser turning of micro-grooves on ceramics is highly demanded in the present industry because of its wide and potential uses in various fields such as automobile, aerospace and bio-medical engineering applications, etc. Experiments have been conducted on laser micro-grooving of aluminum oxide (Al2O3). The central composite second-order rotatable design (CCD) had been utilized to plan the experiments and response surface methodology was employed for developing empirical models. Analysis on machining characteristics of pulsed Nd:YAG laser micro-grooving operation was made based on the developed models. In this study, lamp current, pulse frequency, pulse width, assist air pressure and cutting speed of work piece are considered as laser machining process parameters. The process performances such as upper deviation (Yuw), lower deviation (Ylw) and depth (Yd) characteristics of laser-turned micro-grooves produced on cylindrical work piece made of Al2O3 were evaluated. Analysis of variance (ANOVA) test had also been carried out to check the adequacy of the developed regression empirical models. The observed optimal process parameter settings are lamp current of 22.517 A, pulse frequency of 1.477 kHz, pulse width of 2.394% of duty cycle, cutting speed of 10.4283 rpm and assist air pressure of 1.3 kgf/cm2 for achieving minimum upper deviation, lower deviation and depth of laser-turned micro-grooves, and finally the results were experimentally verified. From the analysis, it was found that proper control of the process parameters lead to achieve minimum upper deviation, lower deviation and depth of laser-turned micro-grooves produced on cylindrical workpiece of Al2O3.

In-Line Control of a Freeze-Drying Process in Vials

Abstract: This article deals with the control of a freeze-drying process in vials. Firstly, the results that can be obtained when the operation is carried out at constant chamber pressure and shelf temperature are predicted by means of mathematical simulations, using a previously validated detailed model, thus allowing off-line optimization of the process. Further improvements can be obtained if the shelf temperature is varied during the process in such a way that the product temperature is always maintained at the maximum allowable value. This strategy for the in-line control of the process allows to minimize the time required for the primary drying, besides satisfying the process constraints. The possibility of manipulating the chamber pressure for control purposes is also discussed. An alternative strategy based on a simple feedback controller, with proportional-integral action, is also investigated: it is able to control the product temperature at a predetermined value, giving stable and fast responses. The con...

Solving multi-criteria optimization problem in submerged arc welding consuming a mixture of fresh flux and fused slag

Abstract: In the present work, application of the Taguchi method in combination with grey relational analysis has been applied for solving multiple criteria (objective) optimization problem in submerged arc welding (SAW). A grey relational grade evaluated with grey relational analysis has been adopted to reveal an optimal parameter combination in order to obtain acceptable features of weld quality characteristics in submerged arc bead-on-plate welding. The idea of slag utilization, in subsequent runs, after mixing it with fresh unmelted flux, has been introduced. The parentage of slag in the mixture of fresh flux and fused flux (slag) has been denoted as slag-mix%. Apart from two conventional process parameters: welding current and flux basicity index, the study aimed at using varying percentages of slag-mix, treated as another process variable, to show the extent of acceptability of using slag-mix in conventional SAW processes, without sacrificing any characteristic features of weld bead geometry and HAZ, within the experimental domain. The quality characteristics associated with bead geometry and HAZ were bead width, reinforcement, depth of penetration and HAZ width. Using grey relational grade as performance index, we have performed parametric optimization yielding the desired features of bead geometry and HAZ. Predicted results have been verified with confirmatory experiments, showing good agreement. This proves the utility of the proposed method for quality improvement in SAW process and provides the maximum (optimum) amount of slag-mix that can be consumed in the SAW process without any negative effect on characteristic features of the quality of the weldment in terms of bead geometry.

System for extraction of key process parameters from fault detection classification to enable wafer prediction

Abstract: A system, method, and computer readable medium for extracting a key process parameter correlative to a selected device parameter are provided. In an embodiment, the key process parameter is determined using a gene map analysis. The gene map analysis includes grouping highly correlative process parameter and determining the correlation of a group to the selected device parameter. In an embodiment, the groups having greatest correlation to the selected device parameter are displayed in a correlation matrix and/or a gene map.

An Effective Approach for Process Parameter Optimization in Injection Molding of Plastic Housing Components

Abstract: Determining optimal process parameter settings is critical work that extraordinarily influences productivity, quality, and costs of production. Previously, numerous engineers conventionally used trial-and-error processes or Taguchi's parameter design method to determine optimal process parameter settings. However, the application of these methods has some shortcomings. This research applies Taguchi's parameter design method, regression analysis, and the Davidon-Fletcher-Powell method to propose a novel approach for determining the optimal process parameter settings of plastic injection molding under single quality characteristic considerations. This novel approach can avoid shortcomings that originate from the application of trial-and-error processes or the conventional Taguchi parameter design method. The research results revealed that the proposed novel approach can effectively help engineers determine optimal process parameter settings and achieve competitive advantages of product quality and costs.

Process Parameter Interaction Effects during Carbon Nanotube Synthesis in Fluidized Beds

Abstract: The interaction effects between temperature, catalyst properties, fluidization conditions, and deposition time during carbon nanotube (CNT) synthesis by chemical vapor deposition in a fluidized bed were investigated. While numerous investigations have attempted to correlate process parameters with CNT characteristics, selectivity and yield, the interaction between process parameters is often ignored. Parametric interactions in this process have been investigated using a factorial design methodology. Besides the main effects of synthesis temperature, deposition time, and catalyst type, the interaction parameters temperature−time and temperature−catalyst were found to significantly influence the resultant carbon and CNT yields. These results lay the foundation for a detailed parametric analysis toward the optimization of CNT synthesis in fluidized beds, which takes into account these interaction effects.

Determining effect of slurry process parameters on semisolid A356 alloy microstructures produced by RheoMetal process

Abstract: Determining the effect of slurry process parameters on semisolid A356 alloy microstructures produced by the RheoMetalTM process

Thermal-based diagnostic system for process transmitter

Abstract: A process transmitter for measuring a process variable in an industrial process comprises a sensor module, a heating device and transmitter circuitry. The sensor module has a sensor for sensing a process variable of an industrial process and generating a sensor signal. The heating device is connected to the sensor module for generating a heat pulse to influence generation of the sensor signal. The transmitter circuitry is connected to the sensor and the heating device. The transmitter circuitry verifies operation of the sensor by measuring a change in the sensor signal due to the heat pulse. In one embodiment of the invention, the heat pulse thermally expands a volume of a fill fluid within the process transmitter. In another embodiment, the heat pulse changes a physical property, such as dielectric, of a fill fluid within the process transmitter.

Multiscale roughness analysis in injection‐molding process

Abstract: The roughness of polymer surfaces is often investigated to guarantee both the surface integrity and the surface functionality. One of the major problems in roughness measurement analyses consists in determining both the evaluation length and the reference line (i.e., the degree of the polynomial equation) from which roughness parameters are computed. This article outlines an original generic method based on the generalized analysis of variance and experimental design methodology for estimating the most relevant roughness parameter p, the most pertinent scale, s, and finally, the degree of the polynomial fitting, d. This methodology is then applied to characterize the influence of four process parameters on the final roughness of poly(polypropylene) samples obtained by injection molding. This method allows us to determine the most efficient triplet (p, s, d) that best discriminates the effect of a process parameter q. It is shown that different (p, s, d) values are affected to each process parameter giving finally the scale on which each process parameter modifies the roughness of a polymeric surface obtained by injection molding. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

Investigation of high shear wet granulation processes using different parameters and formulations.

Abstract: This study compared the granulation processes for different formulations using a laboratory-scale high shear mixer. The effects of critical process parameters (impeller speed, chopper speed and kneading time) on granule characteristics were evaluated. The characteristics of the granules studied included the size distribution, friability and morphological properties. The flow profiles of the wet mass and material deposition during the process were also studied. The results obtained showed that the effect of the impeller speed was determined by the starting material system. On the other hand, chopper speeds from 1200 to 3600 rpm and kneading times from 120 to 240 s had a consistent influence on all formulations. Moreover, it was found that the toroidal flow pattern of the wet mass could be maintained for a longer period and granules with a good spherical shape were obtained by removing the chopper during the last 120 s of the granulation process. In addition, the use of the pregelatinized starch in the formulation also led to a reduction in the wall adhesion of the material. It was concluded that the effectiveness of high shear wet granulation could be improved by choosing a proper combination of starting material and process parameters and by monitoring the mass motion during the process.

A method for experimental investigation of the wood chipping process

Abstract: In both the chemical and mechanical pulping process, the logs are cut into wood chips by a disc chipper before fibre separation. To make the wood chipping process more efficient, one have to investigate in detail the coupling between process parameters and the quality of the chips. One objective of this thesis was to obtain an understanding of the fundamental mechanisms behind the creation of wood chips. Another objective with the thesis was to investigate whether it was possible to, in a way tailor the chipping process so as to reduce the energy consumption in a following mechanical refining process.Both experimental and analytical/numerical approaches have been taken in this work. The first part of the experimental investigations, were performed with an in-house developed chipping device and a digital speckle photography equipment.The results from the experimental investigation showed that the friction between the log and chipping tool is probably one crucial factor for the chip formation. Further more it was found that the indentation process is approximately self-similar, and that the stress field over the entire crack-plane is critical for chip creation.The developed analytical model predicts the normal and shear strain distribution and to be more specific, the model can predict the compressive stresses parallel to the fibre direction for an assumed linear elastic and orthotropic material. The analytical distributions were found to be in reasonable agreement with the corresponding distributions obtained from a finite element analysis.To be able to study the chipping process under realistic conditions, which for example means to use chipping rates representative for a real wood chipper, a laboratory chipper was developed. Details regarding the chipper and how to evaluate the force measurements are given together with an example of how the force on the cutting tool (the knife) varies with time during cutting.To investigate the influence of a certain chipping process parameter, the chips were after production in the laboratory chipper, refined in a pilot refiner during conditions optimized for TMP (thermomechanical pulp) and CTMP (chemithermomechanical pulp) processes. It was concluded that the details concerning the chip process had a large impact on e.g. the energy consumption in both first stage and second stage refining. Results showing this are given in this thesis.

Slag recycling in submerged arc welding and its influence on weld quality leading to parametric optimization

Abstract: Slag generated during conventional submerged arc welding (SAW) has been recycled by mixing varying percentages of crushed slag with fresh flux to use in subsequent runs. The influence of using flux-slag mixture on various aspects of SAW weld parameters of bead geometry have been investigated in a quantitative basis. Slag has been reprocessed and reused in submerged arc welding to produce bead-on-plate weld on mild steel plates. Apart from conventional process parameters: voltage (OCV), wire feed rate, nozzle to plate distance (stick-out) and traverse speed, welding has been carried out using various percentages of flux-slag mixture; the % of fused flux in the mixture has been treated as a process parameter. Various bead geometry parameters viz. bead width; reinforcement, depth of penetration and depth of HAZ have been measured for each of weld prepared in the study. Using experimental data, a grey-based Taguchi approach has been applied for parametric optimization of this non-conventional SAW process. The aim was to reveal the optimal amount of slag-mix%, which could be applied in SAW process without imposing any adverse effect on features of bead geometry and HAZ. Optimal result has been checked through confirmatory test.

Experimental dynamics characterization and monitoring of MRR in oxide chemical mechanical planarization (CMP) process

Abstract: Complex interactions and often dynamic variations in the process parameters and state variables are known to influence material removal rate (MRR) in the chemical mechanical planarization (CMP) of SiO2 film deposited on a Si wafer. Experimental investigations reported in this paper support the nonlinear stochastic characteristics of the CMP process dynamics. Prior modeling and monitoring efforts have attributed much of the complex patterns of the signals from the CMP process to extraneous noise. Consequently, these models have somewhat limited predictability. Sensor features that quantify the nonlinear stochastic dynamics of the CMP process are found to be effective surrogates to track variations in certain process parameters. A monitoring approach based on combining these nonlinear dynamic features with conventional statistical descriptors of sensor signals as well as process parameter settings is found to improve the tracking of MRR—which is one of the most important performance variables in the CMP process—by over 20% (linear R2>80%) compared to the use of conventional features in a linear regression setting. The results consistently hold for a variety of process conditions tested using a battery of designed experiments.

Process variable transmitter with acceleration sensor

Abstract: A process variable transmitter (12) for use in an industrial process control or monitoring system includes a transmitter housing and a process variable sensor (72) having a sensor output related to a process variable An accelerometer (80) is coupled to the transmitter and provides an accelerometer output related to acceleration Diagnostic circuitry (82) provides a diagnostic output as a function of the sensor output and the accelerometer output

System and method for optimizing a paper manufacturing process

Abstract: A technique is disclosed for optimizing a quality parameter in a process that is not directly measurable online using conventional measurement devices. The technique includes the use of a first inferential model to predict a value for the parameter based upon other process variables. A second inferential model predicts a residual component of the process parameter based off non-controllable residual variables of the process. The inferential model outputs are combined to produce a composite predicted value which may be further adjusted by an actual prediction error determined via comparison with an offline measurement. The adjusted predicted value is provided to a dynamic predictive model which may be adapted to implement control actions to drive or maintain the quality parameter at a target set point. The technique may further consider cost optimization factors and production reliability factors in order to produce a product meeting the target quality set point or range while considering production requirements and minimizing overall costs.

Selective optical proximity layout design data correction

Abstract: After layout design data has been modified using an OPC process, a repair flow is initiated. This repair flow includes analyzing the modified data to identify any remaining or new potential print errors in the layout data. Regions then are formed around the identified potential print errors, and a subsequent OPC process is performed only on the data within these regions using a different set of process parameters from the process parameters employed by the initial OPC process. This repair flow is iteratively repeated, where a different set of process parameter values for the subsequent OPC process is used during each iteration.

Metal powder laser forming process temperature field detection method and its systematic device

Abstract: The invention relates to a metal powder laser rapid prototyping technology, in particular to a temperature field detecting method and the system device in the working process of the rapid prototyping of the metal powder. The invention adopts dual wavelength infrared image colorimetric temperature measuring method, the optical filters in two wavelengths are alternately arranged in the gathering optical path at different times, the image in the fused bath from two different wavelength are continuously and orderly gathered, and the color matching calculation of the gradation of the two infrared image from different wavelength are performed, according to the relationship between the color matching value and the temperature value, the temperature value of each point of the image is acquired, the temperature value is represented by the tonal value and a gradation image is formed, the gradation image then is processed, and the shape and temperature changing trend is acquired. By adopting the invention, the temperature distribution and the changing trend of the temperature field of the fused bath can be detected in real time during the rapid prototyping process of the metal powder, and then the temperature of the work piece process parameter can be adjusted in real time.

Vision system and method for direct-metal-deposition (dmd) tool-path generation

Abstract: New tool paths are automatically created for rapid prototyping and additive manufacturing processes, facilitating the fabrication of new or repaired parts with superior geometries and/or compositional characteristics. The profile of a source part is imaged from camera picture and point wise offset adjustments. Part profile and process points are automatically generated without teaching by an operator. In the preferred embodiment, point-by-point process variable settings (i.e., laser power, speed and powder flow) are coupled to a closed-loop, direct-metal deposition (DMD) process to fabricate or repair production components using a tool path derived from the profile of the source part. The preferred method includes the steps of detecting the edge of the source part; generating a point-to-point database of the source part based upon the detected edge; and assigning one or more process parameters associated with the additive manufacturing process used to fabricate or repair the production part.

Monitoring laser machining process to be carried out on workpiece, comprises detecting actual measuring values by sensor, which monitors the laser machining process, and determining actual characteristic values from actual measuring values

Abstract: The method comprises detecting two actual measuring values by a sensor, which monitors a laser machining process, determining two actual characteristic values from the two actual measuring values using neural networks, where the actual characteristic values mutually represent an actual fingerprint in a characteristic value range, providing a predetermined point set in the characteristic value range, and classifying the laser machining process by detecting the position of the actual fingerprint relative to the predetermined point set in the characteristic value range. The method comprises detecting two actual measuring values by a sensor, which monitors a laser machining process, determining two actual characteristic values from the two actual measuring values using neural networks, where the actual characteristic values mutually represent an actual fingerprint in a characteristic value range, providing a predetermined point set in the characteristic value range, classifying the laser machining process by detecting the position of the actual fingerprint relative to the predetermined point set in the characteristic value range, regulating a process parameter of an associated actuator, so that the actuator is activated when the actual fingerprint exits the predetermined point set of the characteristic value range. The change of the associated process parameter corresponds to gradients in the characteristic value range, which extends itself from the fingerprint in the direction of the point set in the characteristic value range. The determination of the actual characteristic value from the actual measuring value comprises a process for data reduction or dimension reduction as a main component analysis, multidimensional scaling, support vector machine or support vector classification, or industrial standard organization-manufacturing automation protocol process. The predetermined point set is fixed within the characteristic value range using a learning process. The gradient field of the characteristic value range is determined in different areas at the points in the characteristic value range in dependent of the process parameter, where the points in the characteristic value range are representative for the respective area with respect to the gradients. The gradients of the characteristic value range are determined by variation of the process parameter at a predetermined point of the characteristic value range in dependent of the process parameter. The sensor comprises a photodiode with filter for the determined wavelengths, body- and airborne receiver, and a camera unit with a corresponding surface illumination. The actuator comprises a controller of the laser capacity, a speed controller of a machining head relative to a workpiece, a controller of the focal position of the machining laser beam, a controller of the distance of the machining head to the workpiece, and a controller of lateral offsets. Independent claims are included for: (1) a device for monitoring a laser machining process to be carried out on a workpiece; and (2) a laser machining head for processing a workpiece.

Method and means for controlling an electrolysis cell

Abstract: Method and means for controlling an electrolysis cell for aluminium production by process control inputs, comprising means for measurement of one or more process variable(-s) where the measured value(-s) is led to an estimator. The estimator can be of the Kalman filter type, and estimates the current value of one or more process variable(-s) followed by prediction of the value of said process variable(-s) and/or other process variable(-s). The predicted value(-s) is used to calculate future input control scenario by means of a calculator. The prediction of the process variable(-s) is performed in accordance with a non -linear dynamic model being an integrated part of a process controller.

Dual response surface optimization with hard-to-control variables for sustainable gasifier performance

Abstract: Summary. Dual response surface optimization of the Sasol–Lurgi fixed bed dry bottom gasification process was carried out by performing response surface modelling and robustness studies on the process variables of interest from a specially equipped full-scale test gasifier. Coal particle size distribution and coal composition are considered as hard-to-control variables during normal operation. The paper discusses the application of statistical robustness studies as a method for determining the optimal settings of process variables that might be hard to control during normal operation. Several dual response surface strategies are evaluated for determining the optimal process variable conditions. It is shown that a narrower particle size distribution is optimal for maximizing gasification performance which is robust against the variability in coal composition.

Field device for determining or monitoring a process variable in process automation

Abstract: The invention relates to a field device (1) for determining or monitoring a process variable in process automation, the device comprising a sensor (2), which operates according to a defined measuring principle, and a control/analysis unit (14), which processes and analyzes the measured data provided by the sensor (2) as a function of a safety standard, which is required in the particular safety-critical application, along at least two equivalent measuring paths (MP1, MP2), said control/analysis unit (14) being at least partially implemented as a logic component (4), which can be reconfigured and which has multiple functional modules (5, 6, 7, 8), which can be partially dynamically reconfigured, and said control/analysis unit (14) configuring the function modules (5, 6) in the measuring paths (MP1, MP2, MP3) as a function of the respectively defined safety-critical application such that the field device (1) is designed in accordance with the required safety standard.