Bi-objective hybrid flow shop scheduling with sequence-dependent setup times and limited buffers

The bi-objective hybrid flow shop problem with sequence-dependent setup times and limited buffers is mentioned in this paper. In this environment, there are limited buffer spaces between any two successive stages; thus, maybe there is not enough room for queues of jobs that are waiting in the system for their next operations. This problem is shown to be NP-hard in the strong sense. Up to now, some heuristic and metaheuristic approaches are proposed to minimize makespan or total tardiness of jobs. This paper presents several methods for optimization which consider two objectives simultaneously. The resolution of several specific instances from the open literature with the adaptations of non-dominated sorting genetic algorithm and sub-population genetic algorithm suggest that the proposed algorithms are effective and useful methods for solving this problem.     

Investigation of High-Frequency Guided Wave Modes Applicability in Defect Detection Using Phased Array Ultrasonic Transducer

Russian Journal of Nondestructive Testing - An ultrasonic phased array scanning method was used for lamb wave evaluation of surface and in-depth defects in a steel plate. The ultrasonic guided wave...     

Biosorption of copper by wine-relevant lactobacilli

Must and wine may be contaminated with elevated copper concentrations by the use of fungicides or in course of the vinification process. Hitherto only a few practicable and harmless procedures exist to reduce an excess of copper from must and wine. For this reason we investigated the biosorption of copper by eight wine-relevant Lactobacillus species. Both, living and heat-inactivated cells revealed a significant degree of Cu adsorption. It was shown that Cu binding correlated positively with an increasing pH value of the environment. The highest binding capacity of the tested lactic acid bacteria was found for L. buchneri DSM 20057 with a maximum of 46.17 μg Cu bound per mg cell in deionized water. In must, wine and grape juice Cu was removed less effective which is not solely attributed to low pH-values, but also to specific medium parameters such as intrinsic metal cations, organic acids or phenolic compounds. Nevertheless, about 0.5-1.0 μg Cu per ml could be removed from wine samples, which is sufficient enough to lower critical copper concentrations.     

Multiverse optimizer for structural damage detection: Numerical study and experimental validation

New optimization algorithms have been increasingly developed in the course of the recent years. The accuracy of identified results in optimization‐based damage detection methods depends on the objective function and optimization algorithm. This paper employs multiverse Optimizer (MVO) to solve the optimization‐based damage identification problem. Statistical results obtained by MVO are compared with those of sine cosine algorithm (SCA) and Harris hawks optimization (HHO) in order to perform a comparative study. Two objective functions are used in this optimization problem. The first one is based on the modal assurance criterion (MAC) and the second one on modified total modal assurance criterion (MTMAC). Numerical and experimental examples indicate that the combination of objective function based on MTMAC and MVO algorithm can provide accurate and reliable results in structural damage detection process. MAC is also rejected in competition with MTMAC. While using SCA‐MTMAC, the accuracy of the results is acceptable in some cases. However, HHO‐MTMAC gives weak results in most cases. MVO and SSA are the lowest, and HHO spends significantly more time in terms of computational cost.     

Positional, geometrical, and thermal errors compensation by tool path modification using three methods of regression, neural networks, and fuzzy logic

One of the main sources of inaccuracy in production is machine tool errors. In this study, a method is introduced to model and compensate positional, geometrical, and thermally induced errors of machine tools by an offline technique. Thermal errors are modeled by three ways of multiple linear regression, artificial neural networks, and neuro-fuzzy modeling. The required database is provided by measuring errors using a laser interferometer. Subsequently, the models are evaluated and the best one which is neuro-fuzzy with a mean square error of 0.375 μm is chosen to predict the errors using developed software. The experimental procedure is optimized by a preliminary broad assessment. Volumetric errors are calculated using rigid body kinematic and applied to modify the initial G-codes. The introduced method is validated by compensating errors on a free-form which shows significant average improvement of errors.     

Extended octagonal ring transducers for measurement of tractor-implement forces

The extended octagonal ring transducers are popular devices for force and moment measurements in agricultural engineering research due to its capability in measuring forces independently in two dimensions and resultant moment in one dimension. In this study design, construction and calibration of extended octagonal ring transducers are discussed. The transducers were designed to measure the two force components of the soil reaction with minimum cross-sensitivity. Strain distributions in the extended octagonal rings were analyzed using finite element method to locate optimal strain gauge positions to minimize cross-sensitivity between the two force components. A Data acquisition system consisted of a programmable DT800 data logger with 12 differential voltage and 16 frequency channels, and a PC for storing the data for further graphing and analysis. The system was tested for its sensitivity, cross-sensitivity, linearity and repeatability. The results of the calibration tests revealed that the system was well working for a range of draught and vertical forces up to 25 kN. The results showed a high degree of linearity between bridge output voltage and force applied. The minimum coefficient of determination, R ², was found to be 0.99. The interactions of the applied forces on the orthogonal force bridges were less than one percent. The system could best be used for the measurement of draught (horizontal) and vertical forces where medium size equipment is attached with a tractor.     

Innovative Proof for Elastic Flexure Formulas

The basic problem in teaching mechanics of materials is that some subjects discussed in the reference books are not easy to understand for most of the students. Using experience of many years teaching mechanics of materials, we have been continuously trying to find easier methods to help the students get a better understanding of fundamental concepts. This effort and investigation has led to innovative and simple approaches to prove the equations much easier than the existing ones and also to clarify complicated concept. In this paper, we are offering our innovative proof for elastic flexure formulas as well as an interesting model for the moment sign convention in the cross section of a beam. In this method, considering a portion of a beam under pure bending and obtaining the stress distribution in the cross section and applying the balance of the considered portion, we prove the Elastic Flexure Formulas much easier than the existing methods. Emphasizing on deeper understanding, some notes and a new model are offered during this proof.