Dynamic routing and the performance of automated manufacturing cells

There has been a considerable amount of research done on the “cell formation” problem, in which machining cells are designed to process a family of components. More recently, it has been suggested that machining cells should be designed so that they take advantage of the flexibility for processing parts that have alternate, or multiple machine routing possibilities. It is argued that such flexibility will improve machine utilization as well as other measures of cell performance and may reduce the need for centralized cell loading and scheduling algorithms. Unfortunately, if the cell is automated, routing flexibility requirements can create a complex control problem for the cell controller. In this paper we implement a cell controller designed to handle the requirements of the flexible routing of parts and compare the performance of the cell to the case in which each part has only one routing. We find that significant improvements occur when the cell design is capable of processing parts with flexible routings.     

n-scroll chaos generators: a simple circuit model

n-scroll attractors which are generated from a generalised and simple circuit model are presented. The nonlinear characteristics can be systematically designed by adding comparators. A 5-scroll attractor circuit realisation is shown, which has been experimentally verified using current feedback opamps     

International facilities location: A heuristic procedure for the dynamic uncapacitated problem

It is now well known that most major companies no longer operate in a single market. To penetrate global markets and obtain their benefits, companies are under tremendous pressure to reduce the price of their products, and thus their production and material costs. When a foreign location is used, the components of a product are produced there and final assembly takes place either at the foreign location or at the parent domestic plant. This paper first presents the issues related to international facilities location (IFL) problems, and provides the framework required to deal with such problems. It then presents a heuristic algorithm for solving the IFL problem. Extensive computational experience was gained by solving a variety of IFL problems of different sizes.     

New polymers from plant oil derivatives and styrene‐maleic anhydride copolymers

In this study, styrene maleic anhydride copolymer (SMA2000, Styrene : Maleic Anhydride 2 : 1) is grafted and/or crosslinked with epoxidized methyl oleate, epoxidized soybean oil, methyl ricinoleate (MR), castor oil (CO), and soybean oil diglyceride. Base catalyzed epoxy‐anhydride and alcohol‐anhydride polyesters were synthesized by using the anhydride on SMA, the epoxy or secondary alcohol groups on the triglyceride based monomers. The characterizations of the products were done by DMA, TGA, and IR spectroscopy. SMA‐epoxidized soy oil and SMA‐CO polymers are crosslinked rigid infusible polymers. SMA‐epoxidized soy oil and SMA‐CO showed T_g's at 70 and 66°C, respectively. Dynamic moduli of the two polymers were 11.73 and 3.34 Mpa respectively. SMA‐epoxidized methyl oleate, poly[styrene‐co‐(maleic anhydride)]‐graft‐(methyl ricinoleate), and SMA‐soy oil diglyceride polymers were soluble and thermoplastic polymers and were characterized by TGA, GPC, DSC, NMR, and IR spectroscopy. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Prediction of earthquake damage to urban water distribution systems: a case study for Denizli,Turkey

Prediction of damage to water supply lines during an earthquake is a critical part of seismic planning. This study evaluates the performance of the water supply system in Denizli, Turkey, in the event of an M6, M6.3, M6.5 and M7 earthquake associated with the Pamukkale and Karakova-Akhan Faults. The relative effects of transient ground deformations and permanent ground deformations based on maps of liquefiable soil and zones of predicted lateral ground displacements are compared. The relative effects of the different magnitude earthquakes and pipeline damage relationships on the pipeline performance following a seismic event are assessed.     

Information Content-Based Sensor Selection and Transmission Power Adjustment for Collaborative Target Tracking

For target tracking applications, wireless sensor nodes provide accurate information since they can be deployed and operated near the phenomenon. These sensing devices have the opportunity of collaboration among themselves to improve the target localization and tracking accuracies. An energy-efficient collaborative target tracking paradigm is developed for wireless sensor networks (WSNs). A mutual-information-based sensor selection (MISS) algorithm is adopted for participation in the fusion process. MISS allows the sensor nodes with the highest mutual information about the target state to transmit data so that the energy consumption is reduced while the desired target position estimation accuracy is met. In addition, a novel approach to energy savings in WSNs is devised in the information-controlled transmission power (ICTP) adjustment, where nodes with more information use higher transmission powers than those that are less informative to share their target state information with the neighboring nodes. Simulations demonstrate the performance gains offered by MISS and ICTP in terms of power consumption and target localization accuracy.     

Adaptive neuro-fuzzy computing technique for suspended sediment estimation

This paper investigates the accuracy of an adaptive neuro-fuzzy computing technique in suspended sediment estimation. The monthly streamflow and suspended sediment data from two stations, Kuylus and Salur Koprusu, in Kizilirmak Basin in Turkey are used as case studies. The estimation results obtained by using the neuro-fuzzy technique are tested and compared with those of the artificial neural networks and sediment rating curves. Root mean squared errors, mean absolute errors and correlation coefficient statistics are used as comparing criteria for the evaluation of the models’ performances. The comparison results reveal that the neuro-fuzzy models can be employed successfully in monthly suspended sediment estimation.     

Prediction of Excess Air Factor in Automatic Feed Coal Burners by Processing of Flame Images

In this study, the relationship between the visual information gathered from the flame images and the excess air factor k in coal burners is investigated. In conventional coal burners the excess air factor k. can be obtained using very expensive air measurement instruments. The proposed method to predict k for a specific time in the coal burners consists of three distinct and consecutive stages; a) online flame images acquisition using a CCD camera, b) extraction meaningful information(flame intensity and brightness)from flame images, and c) learning these information(image features) with ANNs and estimate k. Six different feature extraction methods have been used: CDF of Blue Channel, Co-Occurrence Matrix, L_∞-Frobenius Norms,Radiant Energy Signal(RES), PCA and Wavelet. When compared prediction results, it has seen that the use of cooccurrence matrix with ANNs has the best performance(RMSE = 0.07) in terms of accuracy. The results show that the proposed predicting system using flame images can be preferred instead of using expensive devices to measure excess air factor in during combustion.     

Missing data analysis and homogeneity test for Turkish precipitation series

In this study, missing value analysis and homogeneity tests were conducted for 267 precipitation stations throughout Turkey. For this purpose, the monthly and annual total precipitation records at stations operated by Turkish State Meteorological Service (DMI) from 1968 to 1998 were considered. In these stations, precipitation records for each month was investigated separately and the stations with missing values for too many years were eliminated. The missing values of the stations were completed by Expectation Maximization (EM) method by using the precipitation records of the nearest gauging station. In this analysis, 38 stations were eliminated because they had missing values for more than 5 years, 161 stations had no missing values and missing precipitation values were completed in the remaining 68 stations. By this analysis, annual total precipitation data were obtained by using the monthly values. These data should be hydrologically and statistically reliable for later hydrological, meteorological, climate change modelling and forecasting studies. For this reason, Standard Normal Homogeneity Test (SNHT), (Swed-Eisenhart) Runs Test and Pettitt homogeneity tests were applied for the annual total precipitation data at 229 gauging stations from 1968 to 1998. The results of each of the testing methods were evaluated separately at a significance level of 95% and the inhomogeneous years were determined. With the application of the aforementioned methods, inhomogeneity was detected at 50 stations of which the natural structure was deteriorated and 179 stations were found to be homogeneous.