Enhanced Heap-Based Optimizer Algorithm for Solving Team FormationProblem

Team Formation (TF) is considered one of the most significant problems in computer science and optimization. TF is defined as forming the best team of experts in a social network to complete a task with least cost. Many real-world problems, such as task assignment, vehicle routing, nurse scheduling, resource allocation, and airline crew scheduling, are based on the TF problem. TF has been shown to be a Nondeterministic Polynomial time (NP) problem, and high-dimensional problem with several local optima that can be solved using efficient approximation algorithms. This paper proposes two improved swarm-based algorithms for solving team formation problem. The first algorithm, entitled Hybrid Heap-Based Optimizer with Simulated Annealing Algorithm (HBOSA), uses a single crossover operator to improve the performance of a standard heap-based optimizer (HBO) algorithm. It also employs the simulated annealing (SA) approach to improve model convergence and avoid local minima trapping. The second algorithm is the Chaotic Heap-based Optimizer Algorithm (CHBO). CHBO aids in the discovery of new solutions in the search space by directing particles to different regions of the search space. During HBO’s optimization process, a logistic chaotic map is used. The performance of the two proposed algorithms (HBOSA) and (CHBO) is evaluated using thirteen benchmark functions and tested in solving the TF problem with varying number of experts and skills. Furthermore, the proposed algorithms were compared to well-known optimization algorithms such as the Heap-Based Optimizer (HBO), Developed Simulated Annealing (DSA), Particle Swarm Optimization (PSO), Grey Wolf Optimization (GWO), and Genetic Algorithm (GA). Finally, the proposed algorithms were applied to a real-world benchmark dataset known as the Internet Movie Database (IMDB). The simulation results revealed that the proposed algorithms outperformed the compared algorithms in terms of efficiency and performance, with fast convergence to the global minimum.     

The Effect of Surface Pit Treatment on Fretting Fatigue Crack Initiation

This paper analyses the effect of surface treatment on fretting fatigue specimen by numerical simulations using Finite Element Analysis. The processed specimen refers to artificially adding a cylindrical pit to its contact surface. Then, the contact radius between the pad and the specimen is controlled by adjusting the radius of the pit. The stress distribution and slip amplitude of the contact surface under different contact geometries are compared. The critical plane approach is used to predict the crack initiation life and to evaluate the effect of processed specimen on its fretting fatigue performance. Both crack initiation life and angle can be predicted by the critical plane approach. Ruiz parameter is used to consider the effect of contact slip. It is shown that the crack initial position is dependent on the tensile stress. For same type of model, three kinds of critical plane parameters and Ruiz method provide very similar position of crack initiation. Moreover, the improved sample is much safer than the flat-specimen.     

Adsorption and Separation of <Superscript>152+154</Superscript>Eu(III) and <Superscript>60</Superscript>Co(II) Using Cerium(IV) Tungstate

Samples of cerium(IV) tungstate (CeW) inorganic ion exchanger were synthesized using different Ce(IV) salts: (NH₄)₂Ce(NO₃)₆·2H₂O, (NH₄)₄Ce(SO₄)₄·2H₂O, and Ce(SO₄)₂·4H₂O. The samples were characterized using FT-IR and X-ray diffraction. The adsorption behavior of ^152+154Eu(III) and ⁶⁰Co(II) on CeW was studied under batch and dynamic conditions. Factors influencing the adsorption kinetics were examined. Loading and elution behavior of both ions was studied using different eluents. Complete separation of Eu(III) and Co(II) (^152+154Eu and ⁶⁰Co tracers) was achieved using small columns packed with CeW.     

The Extension of the Electronic Speckle Photography to the Measurement of In-Plane Displacement

In this paper, a modified speckle photography technique is demonstrated for the measurement of a variable range of the in-plane displacement. The modification focuses on coupling the diode pump solid state laser DPSS with the conventional speckle photography technique. The DPSS laser emerges different wavelengths to provide speckle patterns of suitable size to measure the desired range of the in-plane displacement. The second harmonic generation in a nonlinear crystal of wavelength 532 nm and the principle diode laser wavelength 808 nm are employed in identifying the object positions within a lateral displacement made by a standard linear stage in the range from few microns up to 1.2 mm. The sensitivity and the correlation of the speckles formed by both wavelengths suit both small and large movements. A continues measurement by the modified technique can be achieved by identifying a scale factor in the uniform area in which both wavelengths are effective, and high correlation between the results obtained by 532 and 808 nm is maintained. The uncertainty in measuring 1.2 mm lateral movement by the modified speckle photography is found to be 26.8 μm.     

Quantum Gas of Polar Molecules Ensembles at Ultralow Temperatures: <Emphasis Type="Italic">f</Emphasis>-wave Superfluids

We investigate novel f-wave superfluids of fermionic polar molecules in a two-dimensional bilayer system with dipole moments polarized perpendicular to the layers and in opposite directions in different layers. The solution of the BCS gap equation reveals that these unconventional superfluids emerge at temperatures on the level of femtokelvin which opens up new possibilities to explore the topological \(f+i f\) phase, quantum interferometry and Majorana fermions in experiments with ultracold polar molecules. The experimental realization of such interesting novel f-wave pairings is discussed.     

Targeting Redox Metabolism in Pancreatic Cancer

Cell metabolism is reprogrammed in cancer cells to meet their high bioenergetics and biosynthetic demands. This metabolic reprogramming is accompanied by alterations in redox metabolism, characterized by accumulation of reactive oxygen species (ROS). Elevated production of ROS, mostly by mitochondrial respiration, is counteracted by higher production of antioxidant defenses (mainly glutathione and antioxidant enzymes). Cancer cells are adapted to a high concentration of ROS, which contributes to tumorigenesis, metastasis formation, resistance to therapy and relapse. Frequent genetic alterations observed in pancreatic ductal adenocarcinoma (PDAC) affect KRAS and p53 proteins, which have a role in ROS production and control, respectively. These observations led to the proposal of the use of antioxidants to prevent PDAC development and relapse. In this review, we focus on the therapeutic strategies to further increase ROS level to induce PDAC cell death. Combining the promotion of ROS production and inhibition of antioxidant capacity is a promising avenue for pancreatic cancer therapy in the clinic.     

High speed electrochemical boring

Electrochemical machining (ECM) is widely used nowadays in a great variety of processes, especially in the aero and auto industries. The main machining processes, where high tool feed rates are required, are drilling, cavity sinking, broaching and grinding. In addition, the non-equilibrium machining processes, where stationary electrodes are utilized, have important practical applications in the fields of deburring and embossing. Electrochemical honing is a non-equilibrium process. EC honing is a new technique which, in spite of being used in some industrial plants, is still not fully described, requiring more information about the process. This work presents a comparative study, between rotating and non-rotating electrodes for the enlargement of conventionally pre-drilled holes. The comparison covers the rate of metal removal, dimensional accuracy, surface finish and power consumption. The beneficial advantages of using high rotational speeds on component accuracy are verified. The results emphasize that each process has its own particular characterization, appropriate field of application and tooling system.     

Influence of ethanol as bore fluid component on the morphological structure and performance of PES hollow fiber membrane for oil in water separation

The relationships among varying bore fluid compositions containing ethanol/water were studied. The ethanol composition was varied in the ratio of 0%, 25%, 50%, 75% and 100%. The membrane dope solutions were prepared from 17.25 wt% polyethersulfone (PES), 0.75 wt% polyethylene glycol (PEG), 3 wt% silicon dioxide sol and 78.25 wt% of 1-methyl-2-pyrrolidone (NMP) via dry-jet spinning process. The membranes’ morphology as a result of varying ethanol ratio in the bore fluid composition was characterized and their effects on crude oil/water emulsion separation were evaluated. Results show that the membrane pore size and porosity decreased with increasing ethanol content in the bore fluid mixture, whereas the inner wall thickness of fibers increased. Furthermore, an increase in ethanol concentration also resulted in a slight increase in water contact angle. The use of 100/0 of ethanol/water resulted in UF membranes with the lowest performance. On the other hand, bore fluid mixture containing 25/75 ethanol/water produced membrane with the best performance for crude oil/water separation. Overall, the use of bore fluid mixture containing 25/75 ethanol/water mixture was found to be a powerful way to tune the morphological properties and performance of HF membrane.     

Water Treatment for Rural Areas with Emphasis on Sudan

ABSTRACT

Groundwater conditions in the South Coast Region of Kenya are examined in terms of the quantity and quality of the water derived from boreholes in the region. Both the quality and quantity are found to be generally acceptable for expected uses in the area A new parameter used to define the degree and sensitivity of violations in the quality conditions is introduced and demonstrated.     

Uses of Hydrophobic Siloxane Polymer (Guilspare®) for Soil Water Management

Abstract

The effectiveness of a non-toxic hydrophobic polymer (Guilspare ®) in irrigated agriculture to reduce soil water evaporation, improve water distribution, enhance salt leaching, and increase field water-use efficiency of crops was studied under laboratory and field conditions. Guilspare®, sprayed on soil as an aqueous solution, reacts with surface soil particles, which become hydrophobic. In a soil column experiment conducted under ambient summer conditions, application of the hydrophobic polymer substantially reduced cumulative evaporation relative to untreated columns. The pattern of water loss from Guilspare® treatments was approximately linear over time, while the pattern of water loss for controls was cyclic. The rates of water loss from control columns were significantly higher within 24 hours of water addition than treated columns. Guilspare® treatment substantially reduced the amount of water loss during the constant rate stage (Stage I) of soil drying. The rates of Stage I drying from control columns were higher than during the falling rate stage (Stage II) of soil drying. The patterns of water and salt distribution with depth were substantially different with moderately saline soil after 36 days of watering. Guilspare® application showed an increase in soil water contents at all soil depths of treated columns relative to controls. Guilspare® treated soil columns also showed increased salt content at lower soil depths than controls. In field trials, yields of Okra (Adelmoschus esculentus), transplanted in April and October 1998 from treated and untreated control plot, at three different rates of irrigation, were higher on treated plots. Treated plots, with 25 percent less water (April-planting) and 50 percent less water (October-planting), gave similar yields to untreated plots. The treatment had a marked effect on suppressing weed infestation of airborne weed seeds. A wider perspective of the potential uses of the polymer in semi-arid and arid countries is proposed including: geomembrane type applications to assist water management in cultivating soils of low water holding capacity; maintaining salt free conditions in the rooting zone of perched soil layers above saline horizons; reductions in water losses during conveyance; and run-off entrapment. This paper is offered as a contribution to stimulating interest in using a relatively new water conservation technology to help increase the water use efficiency of renewable and fossil water in Arabian Gulf Countries.