Using Bad Learners to find Good Configurations

Finding the optimally performing configuration of a software system for a given setting is often challenging. Recent approaches address this challenge by learning performance models based on a sample set of configurations. However, building an accurate performance model can be very expensive (and is often infeasible in practice). The central insight of this paper is that exact performance values (e.g. the response time of a software system) are not required to rank configurations and to identify the optimal one. As shown by our experiments, models that are cheap to learn but inaccurate (with respect to the difference between actual and predicted performance) can still be used rank configurations and hence find the optimal configuration. This novel \emph{rank-based approach} allows us to significantly reduce the cost (in terms of number of measurements of sample configuration) as well as the time required to build models. We evaluate our approach with 21 scenarios based on 9 software systems and demonstrate that our approach is beneficial in 16 scenarios; for the remaining 5 scenarios, an accurate model can be built by using very few samples anyway, without the need for a rank-based approach.Comment: 11 pages, 11 figure

Optimal Location Design for Prediction of Spatial Correlated Environmental Functional Data

The optimal choice of sites to make spatial prediction is critical for a better understanding of really spatio-temporal data. It is important to obtain the essential spatio-temporal variability of the process in determining optimal design, because these data tend to exhibit both spatial and temporal variability. Two new methods of prediction for spatially correlated functional data are considered. The first method models spatial dependency by fitting variogram to empirical variogram, similar to ordinary kriging (univariate approach). The second method models spatial dependency by linear model co-regionalization (multivariate approach). The variance of prediction method was chosen as the optimization design criterion. An application to CO concentration forecasting was conducted to examine possible differences between the design and the optimal design without considering temporal structure

Multi-objective green supply chain optimization with a new hybrid memetic algorithm using the Taguchi method

AbstractThe aim of most supply chain optimization problems is to minimize the total cost of the supply chain. However, since environmental protection is of concern to the public, a green supply chain, because of its minimum effect on nature, has been seriously considered as a solution to this concern. This paper addresses the modeling and solving of a supply chain design for annual cost minimization, while considering environmental effects. This paper considers the cost elements of the supply chain, such as transportation, holding and backorder costs, and also, the environmental effect components of the supply chain, such as the amount of NO2, CO and volatile organic particles produced by facilities and transportation in the supply chain. Considering these two components (cost and environmental effects), we propose a multi-objective optimization problem. In this model, the facilities and transportation options have a capacity constraint and, at each level of the chain, we have several transportation options with different costs. We utilize a memetic algorithm in combination with the Taguchi method to solve this complex model. We also propose a novel decoding method and priority based algorithm for coding the solution chromosome. The performance of the proposed solution method has been examined against the hybrid genetic Taguchi algorithm (GATA) on a set of numeric instances, and results indicate that the proposed method can effectively provide better results than previous solution procedures

Using continuous wavelet transform of generalized flexibility matrix in damage identification

Generalized flexibility matrix method has recently been introduced for identifying damages with the aim of overcoming some shortcomings of the approaches based on flexibility matrix. Researchers that use flexibility matrix to detect damages in structures face truncation errors ensue from cut off higher-order mode shapes, which are difficult to measure in practice. In this paper, a new procedure is presented to detect the damage site in a beam-type structure, where generalized flexibility matrix in conjunction with continuous wavelet transform (CWT) is utilized. Since flaws and cracks cause changes in flexibility of a system, this characteristic can be used as a damage indicator. Gaussian wavelet transform with four vanishing moments as a signal processing method is implemented to find the irregularity in a vector obtained from generalized flexibility matrix which is considered as a sign of damage. This method does not need to have either prior knowledge about the intact structure or its finite element model. The proposed technique is evaluated by numerical and experimental case studies

Postharvest melatonin treatment reduces chilling injury and enhances antioxidant capacity of tomato fruit during cold storage

 In this study, tomato fruit was treated with 50, 100 or 200 µM melatonin and then stored at 5°C for 28 days to investigate the effect of melatonin treatment on chilling injury, nutritional quality and changes in the antioxidant system. Tomato fruit developed chilling injury, manifested as surface pitting and irregular red color development during storage. These chilling injury symptoms, ion leakage and malondialdehyde content were significantly reduced, and proline and carotenoids contents were significantly increased by melatonin treatment. Meanwhile, melatonin substantially reduced O2- production rate and H2O2 content, which result from significantly higher activities of superoxide dismutase, catalase, and peroxidase than control during the storage. These results suggest that melatonin treatment can effectively enhance chilling tolerance and reduce chilling injury. The reduction in chilling injury by melatonin may be associated with enhanced enzymatic and non-enzymatic antioxidants, in favor of membrane integrity and thus low cellular and tissue damage

Исследование влияния технологического процесса изготовления обмоток на дефектность корпусной изоляции асинхронных двигателей

В работе проведено исследование влияния колебаний режимов работы статорообмоточных станков WST-660 и пазоизолировочных станков ИПС-3 на дефектность корпусной изоляции. Получены математические модели дефектообразования в корпусной изоляции обмотки с учетом режимов работы технологического оборудования и качества материала корпусной изоляции в состоянии поставки. Установлено, что изменением режимов работы технологического оборудования можно добиться требуемого качества корпусной изоляции при максимальной производительности оборудования

Disseminated Leishmaniasis Caused by Leishmania tropica in a Puppy from Karaj, Central Iran

A 5-month old puppy with muco-cutaneous lesions in the chin, around lips and eyes was examined physically and microscopically for leishmaniasis. Muco-cutaneous lesions containing a large number of amastigotes of Leishmania spp. were observed. Amastigotes were also detected in liver and spleen of the puppy. The animal was positive with Dipstick rK39 kit and high level of anti-Leishmania antibodies was detected by direct agglutination test (DAT). DNA, Using PCR-RFLP technique extracted from cultured Leishmania promastigotes and L. tropica was identified. This is the first report of concurrent mucosal and visceral involvement of L. tropica in a puppy from Iran