Choosing the optimal intervention method to reduce human-related machine failures

This paper presents a novel method to quantify the effects of human-related factors on the risk of failure in manufacturing industries. When failures can be caused by operators, the decision maker must intervene to mitigate operator-related risk. There are numerous intervention methods possible; we develop a revenue model that provides the decision-maker with a systematic tool to perform a cost-benefit analysis, balancing the advantage of risk reduction, against the direct cost of the intervention method.     

Effects of operator learning on production output: a Markov chain approach

We develop a Markov chain approach to forecast the production output of a human-machine system, while encompassing the effects of operator learning. This approach captures two possible effects of learning: increased production rate and reduced downtime due to human error. In the proposed Markov chain, three scenarios are possible for the machine at each time interval: survival, failure, and repair. To calculate the state transition probabilities, we use a proportional hazards model to calculate the hazard rate, in terms of operator-related factors and machine working age. Given the operator learning curves and their effect on reducing human error over time, the proposed approach is considered to be a non-homogeneous Markov chain. Its result is the expected machine uptime. This quantity, along with production forecasting at various operator skill levels, provides us with the expected production output.     

Highly sensitive kinetic spectrophotometric method for tramadol trace level detection and process optimization using response surface methodology

Tramadol is a centrally acting analgesic‐anodyne agent of high oral bioavailability. The tramadol contains a weakly absorbing chromophore in its molecule and it was determined by kinetic spectrophotometric method in pharmaceutical, urine, and blood plasma. Response surface methodology and the central composite design was applied to study the influence of maximum sensitivity, reagents concentration, temperature, and time on the UV–Vis spectrophotometry analysis of tramadol. Analysis of variance showed a high coefficient of determination (R²) value for responses, confirming adjustment of the models with experimental data. The change in absorbance was followed spectrophotometrically at 478 nm. Under optimum experimental conditions, calibration curve was linear over the range 0.45–100.0 μg/L of tramadol. The limit of detection was 0.12 μg/L of tramadol. The developed method was successfully applied for the determination of tramadol in real samples.     

A new solution for a dynamic cell formation problem with alternative routing and machine costs using simulated annealing

This paper presents an integer-linear programming approach for a cell formation problem (CFP) in a dynamic environment with a multi-period planning horizon. The objectives are to minimize the inter-cell movement and machine costs simultaneously. In dynamic environments, the product mix and demand are different but deterministic in each period. As a consequence, the formed cells in the current period may not be optimal for the next period. Thus, the reconfiguration of cells is required. Reconfiguration consists of re-forming part families, machine groups, and machine relocation. The CFP belongs to the category of NP-hard problems, thus we develop an efficient simulated annealing (SA) method to solve such a problem. The proposed mathematical model is optimally solved and the associated results are compared with the results obtained by the SA run. The results show that the gap between optimal and SA solutions is less than 4%, which indicates the efficiency of the developed SA scheme.     

Measurement of permethrin,deltamethrin and malathion pesticide residues in the wheat flour and breads and probabilistic health risk assessment: a case study in Kermanshah,Iran

ABSTRACT

This study was conducted to investigate the residues of pyrethroid and organophosphorus pesticide in flour and breads which were collected from local markets in Kermanshah province, Iran. Four different types of breads and two types of flour samples with high distribution were taken from market and their residues of pesticides were measured. A simple dispersive liquid–liquid microextraction (DLLME) method with solidification of floating organic drop was developed for the measurement. The health risk of these pesticides on adults and children health was assessed by target hazard quotient (THQ) using Monte Carlo simulation (MCS) method. About, 15% and 11.1% of total samples contained detectable levels of deltamethrin and malathion, respectively. None of the tested samples showed any permethrin residue. The results from all samples showed that none of the pesticides exceeded the maximum residue limits (MRLs). About 85% of pesticide residue detections were observed in tropical and mild weather area which is due to high consumption rate of insecticides in these areas. The percentile 95% of THQ is due to bread ingestion content of deltamethrin which was 0.033 and 0.070 for the adults and children, respectively, while this value for malathion was found to be, 0.015 and 0.030, respectively. In the adults and children for both deltamethrin and malathion, the percentile 95% of THQ value were lower than 1 (acceptable level). The non-carcinogenic health risk assessment indicated that bread consumers in Kermanshah province are not at a considerable risk because of deltamethrin and malathion.     

Triphenylmethylphosphonium Dichromate: An Effective and Chemoselective Reagent for Oxidation of Benzylic Alcohols to the Corresponding Aldehydes and Ketones

An efficient and straightforward method for oxidation of the benzylic alcohols to the corresponding aldehydes and ketones has been accomplished using triphenylmethylphosphonium dichromate (MTPPD) under solvent-free conditions with high chemoselectivity. The reaction is fast with good yields and straightforward workup.     

Thermal analysis and thermo-hydraulic characteristics of zirconia–water nanofluid under a convective boiling regime

Journal of Thermal Analysis and Calorimetry - In this research, flow boiling heat transfer of zirconia–water nanofluid inside a heat exchanger was experimentally investigated. The system was...     

Oxygenation of sulfides catalysed by SBA‐15‐immobilized molybdenum(VI) complex of a bis(phenol) diamine ligand using aqueous hydrogen peroxide as a green oxidant

A highly efficient and reusable molybdenum‐based catalyst has been synthesized by covalent grafting of a bis(phenol) diamine ligand, namely 2‐(((2‐bromoethyl)(2‐((3,5‐di‐tert‐butyl‐2‐hydroxybenzyl)amino)ethyl)amino)methyl)‐4,6‐di‐tert‐butylphenol, onto functionalized ordered mesoporous silica (SBA‐15) followed by complexation with MoO₂(acac)₂. The resulting organic–inorganic hybrid material was found to be a highly effective catalyst for oxygenation of various sulfides to their corresponding sulfoxides or sulfones. The catalyst was characterized using transmission and scanning electron microscopies, X‐ray photoelectron, Fourier transform infrared and atomic absorption spectroscopies, Brunauer–Emmett–Teller surface area analysis and thermogravimetric analysis. Mild reaction conditions, high selectivity and easy recovery and reusability of the catalyst render the presented protocol very useful for addressing industrial needs and environmental concerns.     

V‐N‐C catalysts anchored to mesoporous Al‐SBA‐15 with tailorable pore sizes for the synthesis of spirooxindole dihydroquinazolinones derivatives

Heterogeneous nanoscale catalyst was successfully synthesized via anchoring of V‐bis(2‐aminobenzamide) complex on the Al‐SBA‐15. This modified mesoporous was identified by several characterization techniques, such as X‐ray diffraction, field emission‐scanning electron microscopy, Fourier transform‐infrared, Brunauer–Emmett–Teller and transmission electron microscopy. V‐Bis(2‐aminobenzamide)@Al‐SBA‐15 was found to be an efficient heterogeneous catalyst for the rapid and desirable synthesis of various spirooxindole dihydroquinazolinones derivatives. In addition, the heterogeneous nanocatalyst was chemically stabilized in organic and aqueous solutions as well as can be expeditiously reused for at least seven cycles without a significant loss in catalytic activity.     

A hybrid simulated annealing for solving an extended model of dynamic cellular manufacturing system

This paper develops a mixed-integer programming model to design the cellular manufacturing systems (CMSs) under dynamic environment. In dynamic environment, the product mix and part demand change under a multi-period planning horizon. Thus, the best designed cells for one period may not be efficient for subsequent periods and reconfiguration of cells is required. Reconfiguration may involve adding, removing or relocating machines; it may also involve a change in processing rout of part types from a period to another. The advantages of the proposed model are as follows: considering the batch inter/intra-cell material handling by assuming the sequence of operations, considering alternative process plans for part types, and considering machine replication. The main constraints are maximal cell size and machine time-capacity. The objective is to minimize the sum of the machine constant and variable costs, inter- and intra-cell material handling, and reconfiguration costs. An efficient hybrid meta-heuristic based on mean field annealing (MFA) and simulated annealing (SA) so-called MFA–SA is used to solve the proposed model. In this case, MFA technique is applied to generate a good initial solution for SA. The obtained results show that the quality of the solutions obtained by MFA–SA is better than classical SA, especially for large-sized problems.