Colour removal from a simulated dye wastewater using a two-phase anaerobic packed bed reactor

In recent years, rapid technological advances in the textile and dyeing industry have yielded benefits to society but have also generated new and significant environmental problems. The treatment alternatives applicable for the removal of colour vary, depending upon the type of dye wastewater. A synthetic, simulated mixed dye waste (Basic Yellow 28, Basic Yellow 21, Basic Red 18.1, Basic Violet Red 16, Basic Red 46, Basic Blue 16, Basic Blue 41) representing a known waste from a fibre production factory, was investigated. The biological process of anaerobic digestion has been recognised as a simple and energy-efficient means of treating and stabilising a wide range of organic industrial wastewaters. This study sets out to demonstrate the effect of different loading rates, dye concentrations and hydraulic retention times (HRTs) on colour removal efficiency under mesophilic anaerobic conditions. The reactor was operated under mesophilic conditions at different organic loading rates (OLRs) and HRTs for nine months. The results of this study show that a 2-stage mesophilic anaerobic up-flow packed bed reactor can remove up to 90% of the colour from a mixed cationic dye containing 1000 mg/l of dye. Colour removal efficiency falls as the influent dye concentration increases, but rises with increased hydraulic retention time and increased organic loading. The primary colour removal mechanism was one of biosorption with subsequent biodegradation. Acetoclastic methanogens were moderately inhibited at low organic loading rates of 0.25 kg COD/m3 d, at which level, acidogenesis and acetogenesis appeared to be unaffected. Inhibition of acidogenesis became marked at higher OLRs (1 kg COD/m3 d) and when the HRT was reduced from 5 to 3 days.     

A genetic algorithm for the single machine preemptive scheduling problem with linear earliness and quadratic tardiness penalties

In this paper, we consider the single machine preemptive scheduling problem with linear earliness and quadratic tardiness penalties, with no machine idle time. The problem is strongly NP-hard. We proposed a new mathematical model, with non-linear terms and integer variables. We develop a genetic algorithm for solving the problem in medium and large size. The proposed procedure is compared with optimal solutions for the smaller instance sizes. The genetic procedure is also quite close to the optimum and provided an optimal solution for most of the test problems. Numerical examples show that the proposed algorithm is efficient and effective. Scheduling with early and tardy penalties has received extensive attention from the scheduling community because of its practical significance. Single machine scheduling environments actually occur in several practical applications. Also, the performance of many production systems is often determined by the schedules for a single bottleneck machine. Furthermore, the study of single machine problems frequently provides outcomes that prove functional for more complex scheduling areas.     

The Effect of Particle Size on the Mechanical and Microstructural Properties of Freeze‐Casted Macroporous Hydroxyapatite Scaffolds

Two different hydroxyapatites with the particle sizes of 3.9 and 1.69 μm were chosen. Slurries with initial hydroxyapatite concentration of 15 vol% were prepared. Different cooling rates from 2 to 14°C/min were utilized. The specimens were sintered at different temperatures of 1250–1350°C. The phase composition (by X‐Ray Diffraction), microstructure (by Scanning Electron Microscopy), mechanical characteristics, and the porosity of sintered samples were assessed. The porosity of the sintered samples was in range of ~57–83%, and the compressive strength varied from ~1.7 to 15 MPa. The mechanical strength of the scaffolds increased as a function of cooling rate and sintering temperature.     

A DEA approach for comparing solution efficiency in U-line balancing problem using goal programming

Line balancing problem plays an important role in the decision making process to increase efficiency and productivity. Recently, U-shaped layout in many production lines has replaced the traditional straight line layout using just-in-time concept. Here, we propose a model, using multi-objective decision making approach to the U-shaped line balancing problem, to offer enhanced decision maker flexibility, by allowing for conflicting goals. The assembly line operation efficiency is the most significant aim in our study, and this efficiency relates to management of resources and the solution of line balancing problem. First, the U-shaped line balancing problem is solved considering the model's goals. Then, the index function of assembly line balancing is determined and the efficiencies of the optimal solution outputs are evaluated using data envelopment analysis (DEA). Finally, the discrimination weakness and distribution of illogical weight in simple DEA models are resolved using a mixed method.     

Light microscopy of Pakistani Berberis leaf cuticles and its taxonomic implications

Taxonomy of the genus Berberis is quite complex, due to overlapping morphological characters, making it very difficult to differentiate the species within the genus. In order to resolve this taxonomic complexity, the foliar anatomy of 10 Berberis L. species was carried out, for the first time from Pakistan, using light microscopy (LM). Significant variation in terms of epidermal cells shape, size, cell wall pattern, and stomata type was observed. B. baluchistanica has the largest epidermal cells, Adaxial: length = 45–(53.9 ± 3.6)–62.5 μm; and width = 22.5–(26.3 ± 1.3)–30 μm; Abaxial: length = 37.5–(43.25 ± 2.5)–50 μm; and width = 20–(22.6 ± 0.8)–25. The highest number of stomata was observed in B. glaucocarpa as 62 on the abaxial surface while the lowest number of stomata was recorded in B. baluchistanica as 8 on the adaxial surface. Of 10 investigated species, 6 possess anomocytic type stomata, while 2 species that is, B. aitchisonii and B. parkeriana have both anomocytic and anisocytic stomata while B. baluchistanica and B. calliobotrys have only paracytic type stomata. The highest number of cells per unit area was present on the adaxial surface of B. calliobotrys ranging from 245–(252.4)–260 followed by B. parkeriana with 209–(227.8)–250 on the abaxial surface. Stomatal index (SI) also varied considerably and was the lowest (2.6) percentage in B. baluchistanica and highest (31.9) percentage in B. kunawurensis. A taxonomic key based on micro‐morphological characters is provided for species identification.     

A nondominated ranked genetic algorithm for bi-objective single machine preemptive scheduling in just-in-time environment

Motivated by just-in-time (JIT) manufacturing, we study the bi-objective scheduling problem of minimizing the total weighted earliness and the number of tardy jobs on a single machine, in which machine idle time and preemption are allowed. The problem is known to be NP-hard. In this paper, we propose a new mathematical model, with nonlinear terms and integer variables which cannot be solved efficiently for medium- and large-sized problems. A method combining the new ranked-based roulette wheel selection algorithm with Pareto-based population ranking algorithm, named nondominated ranking genetic algorithm (NRGA), has been presented to find nondominated solutions in a reasonable time. Various operators and parameters of the proposed algorithm are reviewed to calibrate the algorithm by means of the Taguchi method. A number of numerical examples are solved to demonstrate the effectiveness of the proposed approach. The solutions obtained via NRGA are compared against solutions obtained via ε-constraint method in small-sized problems. Experimental results show that the proposed NRGA is competitive in terms of the quality and diversity of solutions in medium- and large-sized problems.     

Predictive simulation-based lighting and shading systems control in buildings

This paper presents a prototypically implemented daylight-responsive lighting and shading systems control in buildings that makes use of real-time sensing and lighting simulation. This system can control the position of window blinds and the status of the luminaires. It operates as follows: (1) at regular time intervals, the system considers a set of candidate control states for the subsequent time step; (2) these alternatives are then virtually enacted via a lighting simulation application that receives input data from a self-updating model of sky (luminance distribution maps obtained via calibrated digital photography), room, and occupancy; (3) the simulation results are compared and ranked according to the preferences (objective function) specified by the occupants and/or facility manager to identify the candidate control state with the most desirable performance.     

Shading and lighting operation in office buildings in Austria: A study of user control behavior

Occupants of buildings typically operate devices such as windows, shades, luminaires, radiators, and fans to bring about desirable indoor environmental conditions. These control actions can have a significant impact on buildings’ performance (energy use, indoor climate). A better understanding of control-oriented user behavior can not only facilitate more accurate predictions of buildings’ performance, but also support the effective operation of buildings’ service systems. This paper describes a study of control-oriented user behavior (as related to systems for lighting and shading) in three office buildings in Austria. The results specifically shed light on the relationships between control actions and environmental conditions inside and outside buildings.     

Surface functionalized cadmium telluride quantum dots for the optical detection and determination of herbicides

An optical sensor for detection of herbicides was developed through the functionalization of CdTe quantum dots (CdTe-QDs) with cysteamine hydrochloride. The functionalized CdTe-QDs was characterized with various physicochemical methods such as X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, energy dispersive X-ray analysis, Ultraviolet–visible and photoluminescence spectroscopies. The optical band gap of the functionalized CdTe-QDs as calculated by using Tauc plot was 3.75 eV. It was found that the fluorescence intensity of the functionalized CdTe-QDs quenched linearly in the presence of different herbicides according to the Stern–Volmer equation. Thus, the functionalized CdTe-QDs can be used as simple, rapid, inexpensive, and optical sensitive sensor for practical detection of herbicides.     

Non-dominated ranked genetic algorithm for a multi-objective mixed-model assembly line sequencing problem

The increasing market demand for product variety forces manufacturers to design mixed-model assembly lines (MMAL) on which a variety of product models similar to product characteristics are assembled. This paper presents a method combining the new ranked based roulette wheel selection algorithm with Pareto-based population ranking algorithm, named non-dominated ranking genetic algorithm (NRGA) to a just-in-time (JIT) sequencing problem when two objectives are considered simultaneously. The two objectives are minimisation the number of setups and variation of production rates. This type of problem is NP-hard. Various operators and parameters of the proposed algorithm are reviewed to calibrate the algorithm by means of the Taguchi method. The solutions obtained via NRGA are compared against solutions obtained via total enumeration (TE) scheme in small problems and also against four other search heuristics in small, medium and large problems. Experimental results show that the proposed algorithm is competitive with these other algorithms in terms of quality and diversity of solutions.