RTM Hemp Fibre-Reinforced Polyester Composites

Hemp fibre-reinforced polyester composites were prepared using a Resin Transfer Moulding (RTM) technique and the flexural and impact behaviour investigated. Flexural stress at break and flexural modulus showed an increasing trend with fibre content. Impact strength was found to decrease at low fibre content, then gradually increase with further addition of fibres.A strong interfacial adhesion between hemp and polyester was obtained using chemically modified hemp. This modification consisted in introducing reactive vinylic groups at the surface of the fibres, via esterification of hemp hydroxyl groups, using methacrylic anhydride. Increased bonding between fibres and matrix did not affect the flexural stress at break of the composite but was detrimental to toughness. This behaviour was ascribed to a change in the mode of failure, from fibre pull-out to fibre fracture, resulting in a marked reduction in the energy involved in the failure of the composite, leading to a more brittle material.     

Survival of Helicobacter pylori in Turkish fermented sucuk and heat-treated sucuk during production

The aim of this study was to investigate the survival of Helicobacter pylori during production of sucuk (Turkish fermented sausage). The sucuk mixture was inoculated with H. pylori ATCC 43504 to produce a final level in the mixture of ～5 × 10(6) CFU/g. Samples in group I were fermented and dried traditionally at 22°C for 7 days. Samples in groups II and III were subjected to the traditional fermentation at 22°C for 3 days. After fermentation, group II samples were fermented and dried at 35°C for 4 days and group III samples were treated with heat until the core temperature reached 65°C. On the first day of fermentation, a 1-log reduction in H. pylori was found in all groups. The H. pylori levels in all groups increased by about 1 log CFU/g by the third day of fermentation and reached the inoculation level. On the fifth and seventh days of fermentation, no appreciable change occurred in the level of H. pylori in groups I and II. After heat treatment, the H. pylori levels were below the level of detection. These results suggest that H. pylori can grow during sucuk fermentation and that a heat treatment should be used during sucuk processing to destroy H. pylori.     

Fire retardant properties of intumescent polypropylene composites filled with calcium carbonate

This study was aimed to investigate the influence of calcium carbonate (CaCO₃), a widely used filler, on the fire retardancy of intumescent polypropylene composites. Two intumescent systems based on (1) mixture of ammonium polyphosphate (APP) and pentaerythritol and (2) surface‐modified APP (m‐APP) were examined. In terms of steady heat release rate, total heat evolved, and fire growth index determined by mass loss calorimetry, m‐APP performed markedly superior to APP‐pentaerythritol. The presence of CaCO₃ in both intumescent formulations caused significant losses in fire retardant performance assessed by mass loss calorimetry, limiting oxygen index and UL‐94 tests. Peak rates of heat release and mass loss during combustion, and total heat evolved on combustion were increased, whereas time to ignition was decreased. Characterization of fire residues ascribed the mechanism of deterioration in fire retardancy to the formation of porous and nonexpanded crystalline calcium phosphate/CaCO₃ residues during combustion rather than the amorphous protective intumescent chars formed in the absence of CaCO₃. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Statistical and neural network assessment of the compression index of clay-bearing soils

The compression index is used to estimate the consolidation settlement of clay-bearing soils. As the determination of compression index from oedometer tests is relatively time-consuming, empirical equations based on index properties can be useful. In this study the performance of widely used single and multi-variable empirical equations was evaluated using a database consisting of 135 test data. New empirical equations were developed utilizing least square regression analysis. In addition, an artificial neural network (ANN) with eight input variables was also developed to estimate the compression index. It was concluded that ANN provides the best results.      

Multi-response optimization of process parameters for remediation of tetrachloroethylene pools by surfactants: Application of Taguchi design of experiment and Artificial Neural Network

Within the scope of the study, the effectiveness of the experimental conditions was tested by performing a multi-response Taguchi experimental design for the optimization of the minimum cost remediation performance with Tween 80, Methyl beta cyclodextrine (MCD) and Sodium dodecyl sulfate (SDS) from tetrachloroethylene (PCE) contaminated porous media. Tween 80, MCD and SDS were extensively used in cosmetic industry as emulsifier. Both time of remediation and cost of remediation were studied as two separate response variables in three replicate experiments conducted according to the Taguchi L9 orthogonal experimental design. In the multi-response Taguchi analysis, the sensitivity analysis was performed by systematically changing the weights determined for two separate response variables in the calculation of total loss of quality (TNQLj). Optimum experimental conditions were determined with the help of the calculated multi-response signal/noise (S/N) ratios (MRSN). The results show that the type of Flushing Agent is the most important factor in optimizing the remediation time and remediation cost for the removal of dense non-aqueous phase liquid (DNAPL) PCE mass. Flushing rate is considered to be the least contributing factor. Furthermore, the results of the analysis of variance (ANOVA) showed that all parameters used in the system had a significant effect on the experimental results and the Taguchi method could explain 97.15% of the Remediation Time and 92.03% of the Remediation Cost. Afterwards, the data obtained from the experiments performed according to the experimental design were modelled using Artificial Neural Network (ANN) to estimate the remediation performance and remediation cost without performing new experiments.     

Dynamic job shop scheduling for missed due date performance

In this research, missed due date in terms of mean absolute lateness (MAL) and mean square lateness (MSL) has been considered as a performance criterion and a scheduling study has been performed to improve the missed due date performance in dynamic, stochastic, multi machine job shop environments. In the study, a new due date assignment model was proposed and a new dynamic dispatching rule was developed. The results indicate that the proposed due date assignment model is very successful for improving the missed due date performance and the developed dispatching rule is also very successful for meeting the assigned due dates.     

EM Based Data Detection Algorithm for Downlink of a Single Hop Relaying Network

This work proposes an Expectation–Maximization (EM) based joint channel estimation and data detection algorithm and a time sharing hopped cooperative communication for the downlink of a communication network. The algorithm was applied to the downlink of a single hop relaying network. The relaying technique is a variant of the decode and forward technique. However, it is a time sharing single hop cooperative communication technique applied to a multi-carrier code division multiple access used in cellular networks. The proposed EM algorithm is compared with the minimum mean square estimation (MMSE) method using simulation. In addition, the proposed relaying technique is compared with cooperative communication on the considered cellular network for frequency-selective fading channels. Simulation results illustrate that our proposed EM algorithm performs better than the MMSE algorithm and that our proposed relaying technique is better than the normal case and the cooperative diversity case.     

Strength of short fiber reinforced polymers: Effect of fiber length distribution

In this study, the prediction of mechanical strength of short fiber reinforced plastics (SFRPs) is made possible by obtaining a Fiber Length Distribution (FLD) efficiency factor, η_FLD, from the formerly known twofold discrete strengthening equation of Kelly–Tyson. The unified parameter η_FLD is developed involving both the effects of fiber breakage and resulting distribution, fiber volume fraction and fiber and interface properties, so that they can be incorporated into modified rule of mixtures (MROM). This procedure helps to clarify the experimentally observed loss in strengthening rate with increasing fiber fraction. By adapting a few experimentally determined distributions to a Weibull type function, the analytical solutions described in this study establish the exploration of the strength of SFRPs in the entire fiber content range or can reveal the interfacial bond strength. After investigating the effects of fiber and interface parameters on strengthening efficiency, it is found that common fiber‐matrix combinations possessing intermediate critical fiber lengths show a significant decrease in strengthening efficiency with increasing fiber content at low fiber loadings. On the contrary, higher and lower critical fiber lengths yield less significant losses. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Application of artificial neural network to estimate power generation and efficiency of a new axial flux permanent magnet synchronous generator

An estimation study on the output power and the efficiency of a new-designed axial flux permanent magnet synchronous generator (AFPMSG) is performed. For the estimation algorithm, a multi-layer feedforward artificial neural network (ANN) is developed. Various experimental results from the generator have been used for the training purpose in the cases of different electrical loads and rotational speeds. Some experimental data is kept out of the training process for testing the network and the errors have been evaluated after the formation of the network. According to the findings, a network with three layers has been adequate to achieve very good error percentage between the ANN and laboratory studies. The maximal testing error percentages are found to be nearly 3% and 4% for the output power and efficiency estimations, respectively. According to that finding, the developed ANN has a good property that it can be used in place of the designed generator, especially when the generator mathematical model is required. In addition, since power and efficiency are important for present applications, the present tool can be used to estimate the data for those characteristics of the machines and even it can be beneficial for the applications, where a nonlinear relationship among the power generation, generator efficiency, speed and load is required.     

Cogging torque reduction by optimal design of PM synchronous generator for wind turbines

In this study, design and optimization of a surface-mounted permanent magnet synchronous generator (PMSG) have been carried out for use in low power wind turbines. In the successive optimization steps based upon the parametric solution method, design parameters of skew, pole embrace, and pole arc offset are chosen to be optimized so that the cogging torque is reduced. Cogging torque is a type of torque ripple coming from the machine design and causes undesired vibration and acoustic noise during the operation of machine. Moreover, although the effect of cogging torque in high power surface-mounted PMSGs is not sensible, it becomes important in low power applications to maintain good dynamical behavior. Analytical and finite element analysis (FEA) are conducted after obtaining the magnet structure that provides minimum cogging torque. Electrical and electromagnetic distributions are presented according to the changes in the corresponding design parameters. While the cogging torque in the initial design is 522.7 mNm, it has been reduced to 49.1 mNm in the optimized generator, which in turn means an improvement of about 90%. The generator under consideration has the specifications of 2.5 kW, 120 V, 14-pole with an inner type-rotor.