Efficient metaheuristics for pick and place robotic systems optimization

This paper deals with a pick and place robotic system design problem. The objective is to present an efficient method which is able to optimize the performances of the robotic system. By defining the suitable combination of scheduling rules, our method allows each robot to perform the assigned pick and place operations in real time in order to maximize the throughput rate. For that, we have developed different resolution methods which define the scheduling rule for each robot in order to seize the products from the first side of the system and to place them on the second side. We suggest three metaheuristics which are the ant colony optimization, the particle swarm optimization and the genetic algorithm. Then, we try to select the best algorithm which is able to get the best solutions with the lowest execution times. This is the main advantage of our methods compared to exact methods. This fact represents a great interest taking in consideration that our methods must respect a strong industrial constraint regarding the functioning of a real industrial robotic system. This constraint states that the answer time to manage the seizing strategies of the robots must be less than 1 second. Numerical results show that the different algorithms perform optimally for the tested instances in a reasonable computational time.     

Eco-friendly method to synthesize and characterize 2D nanostructured (1,2-bis(diphenyl-phosphino)ethyl) tungsten tetracarbonyl methyl red/copper oxide di-layer thin films

Three-layer thicknesses (\({T}_{1 }= 50\), \({T}_{2 }= 75\) and \({T}_{3 }= 100\) nm) of 1,2-bis(diphenylphosphino)ethyl tungsten tetracarbonyl methyl red (DPE-W-MR) were deposited onto the CuO thin film (50 nm) to produce DPE-W-MR/CuO di-layer thin films by sol–gel spin-coating technique. The composition and the chemical structure of the as-prepared thin films were characterized using various techniques including elemental analysis, Fourier transform infrared spectroscopy, \(^{1}\hbox {H}\)-NMR and X-ray diffraction (XRD). Scanning electron microscopy was used to investigate the size and shape of the CuO nanoparticles and the fabricated thin films. The films are crystalline as evidenced by the XRD pattern and DPE-W-MR has an orthorhombic crystal system. The crystallite size was calculated from an analysis of the line broadening features using the Scherrer formula; the average crystallite sizes of DPE-W-MR/CuO di-layer thin films are 52.92, 56.24 and 72.26 nm for \({T}_{1}\), \({T}_{2}\) and \({T}_{3}\), respectively. Thermogravimetric analysis and the thermal curve of DPE-W-MR complex were studied. Optical properties of DPE-W-MR/CuO di-layer thin films are discussed. The optical band gap energies of DPE-W-MR di-layer thin films/CuO decreased (2.25, 2.1 and 1.88 eV) as the film thickness increased (from \({T}_{1}\) to \({T}_{3})\). Based on the optical results and the quantum confinement effects, the DPE-W-MR/CuO di-layer thin films may be candidates as semiconductor materials for optoelectronic devices.     

Simulation based optimization of a train maintenance facility

In this paper, a simulation based optimization method is developed for optimization of scheduling policies. This method uses the technique of coupling industrial simulation software with a multi-objective optimizer based on genetic algorithms. It is used to optimize the performances of a railway maintenance facility by choosing the best scheduling policy. Numerical results show that a significant improvement is achieved with respect to the simulation results of the existing system. The method adapted by our problem can be extended to deal with the selection of scheduling rules in using other types of simulation models.     

Auto-organization approach with adaptive frame periods for IEEE 802.15.4/zigbee forest fire detection system

Wireless Networks - Using efficiently the wireless sensor networks based on IEEE 802.15.4/zigbee remains a real challenge for the forest fire detection and monitoring applications. The most...     

The combination of photocatalysis process (UV/TiO2(P25) and UV/ZnO) with activated sludge culture for the degradation of sulfamethazine

The major factors affecting the removal efficiency of sulfamethazine (SMT) by photocatalysis process in the presence of TiO₂ P25 or ZnO, namely the pH, the amount of catalyst and the initial SMT concentration were examined. The obtained results showed the absence of adsorption of SMT on the catalysts and the absence of degradation of SMT by direct photolysis under UV light in the absence of catalyst. The variation of the pH solution in the range 4–9 did not cause any significant degradation of SMT. The optimal amounts of each catalyst were, respectively, 0.5 and 0.25 g/L for TiO₂ P25 and ZnO. Increasing the initial SMT concentration impacted negatively the removal efficiency, which decreased from 31% to 13% and from 100% to 27% in the presence of TiO₂ P25 and ZnO in the presence of 10 mg/L and 50 of SMT after 30-min reaction time, respectively. The obtained results showed better efficiency of ZnO than TiO₂ P25 regarding both removal efficiency and chemical oxygen demand (COD) abatement. However, removal efficiency and COD abatement were not complete, even after 7 h of photocatalysis, about 92% and 41%, respectively. The biodegradability was examined after photocatalysis performed in the following conditions: [SMT]₀ = 50 mg/L, pH = 6, T = 25°C, ω = 360 rpm and 0.5 g/L of TiO₂ P25 or 0.25 g/L of ZnO. In these conditions, the removal efficiencies were, respectively, 26% and 41% in the presence of TiO₂ P25 and 55 and 92% in the presence of ZnO after 4 and 7 h of pretreatment times, respectively. The BOD₅/COD ratio increased substantially and, respectively, from 0 to 0.25 and from 0 to 0.16 in the presence of TiO₂ P25 and ZnO after 7 h of irradiation. Even if the limit of biodegradability (0.4) was not achieved, a subsequent biological treatment was considered in the presence of TiO₂ P25, leading to 58% COD abatement after a 28-day culture.     

Experimental and numerical investigations of an orifice type cryogenic pulse tube refrigerator

A helium filled orifice type pulse tube refrigerator (OPTR) was designed, built and operated to provide cryogenic cooling. The OTPR is a traveling wave thermoacoustic refrigerator that operates on a modified reverse Stirling cycle. The experimental studies are carried out to characterize the performance of the OPTR at various values of the mean pressure of helium (0.35 MPa–2.2 MPa), amplitudes of pressure oscillations, frequencies of operation and sizes of orifice opening. A detailed time-dependent axisymmetric computational fluid dynamic (CFD) model of the OPTR is also developed to predict its performance. In the CFD model, the continuity, momentum and energy equations are solved for both the refrigerant gas (helium) and the porous media regions (the regenerator and the three heat-exchangers) in the OPTR. An improved representation of heat transfer in the porous media is achieved by employing a thermal non-equilibrium model to couple the gas and solid (porous media) energy equations. The computational results are compared with specific experimental results to validate the numerical model. The model predictions show better temporal comparisons with the experimental results when the effects of wall thicknesses and natural convective losses of the various components of the OPTR to the surroundings are included in the model.     

Heat transfer in a rectangular chamber with differentially heated horizontal walls: Effects of a vibrating sidewall

Heat transfer in a gas-filled closed enclosure with differentially heated horizontal walls is investigated numerically. One of the sidewalls vibrates with specified frequency and amplitude to induce forced convective flows in the enclosure. The vibrating and the stationary sidewalls are considered to be thermally insulated while the two horizontal walls are differentially heated. To simulate the flow field, the full compressible form of the Navier–Stokes equations is considered and solved by a highly accurate flux-corrected transport algorithm. In the numerical model, temperature dependant heat conductivity and viscosity are taken into account. The presence of acoustic streaming is found to have significant effect on the heat transfer. Also the presence of temperature gradients in the enclosure is found to affect the formation of acoustically induced streaming flows.     

Preliminary studies to determine the chaperoning properties of bovine casein and crystallin proteins at reducing beef muscle protein aggregation during heating

The ability of small heat shock proteins (sHSP) at preventing the aggregation and precipitation of unfolded and misfolded proteins because of changes in pH and temperature is widely recognised. The performance of sHSP from bovine lens extract at protecting sarcoplasmic proteins from heat induced denaturation and aggregation was compared with other chaperones including bovine serum albumin, α_s‐casein, β‐casein and a synthetic peptide based upon αA‐crystallin (AAC). Beef sarcoplasmic proteins were heated in the presence or absence of exogenous chaperone and the solubility, surface hydrophobicity and enzymatic activities of the sarcoplasmic proteins was determined. Lens extract prevented the aggregation of sarcoplasmic proteins, maintaining solubility and clarity up to 65 °C relative to 60 °C for β‐casein. By contrast, α_s‐ and β‐casein proteins protected the activity of endogenous enzymes at temperatures between 37 °C and 52 °C, unlike lens sHSP. Our findings support the addition of casein proteins as potential thermal stabilisers of meat proteins in food systems.     

Plasma deposition of adhesion-promoting polymer layers onto polypropylene for subsequent covering with thick fire retardant coatings

Melamine resins were used as 50-μm-thick fire retardant coatings for polypropylene (PP). Preceding deposition, low-pressure plasma polymer films of allyl alcohol were coated onto PP to improve the adhesion between PP and melamine resin coatings. The efficiency of such fire retardant coatings was confirmed by flame tests. The plasma-deposited polymer and the dip-coated melamine resin films were characterized by Fourier transform infrared-attenuated total reflectance spectroscopy and X-ray photoelectron spectroscopy (XPS). The adhesion of coatings was measured using a 90° peel test with a doubled-faced adhesive tape. To detect the locus of failure, the peeled layer surfaces were inspected using optical microscopy and XPS. Thermal properties of PP thick melamine resin-coated films were analyzed by thermogravimetric analysis.