Comparison of Two Drying Schedules for European Hophornbeam (Ostrya carpinifolia Scop.) Lumber

Two types of conventional kiln-drying schedules (mild and harsh) based on moisture content (MC) were compared with regard to time, drying quality, and energy cost. The results were evaluated according to the classification of the European Drying Group. Proper drying periods of mild and harsh schedules were found to be 550 and 514 h, respectively. Evaluations in terms of drying quality indicated that better results were achieved with the mild schedule, especially when comparing drying defects and final MC. From an energy efficiency point of view, the harsh schedule, by saving 36 h of drying time, reduced electricity by 594 KWh and was therefore found to be $65 more profitable in this trial.     

Noise exposed of the operators of combine harvesters with and without a cab

A considerable number of the combine harvesters in Turkey are rather old and used without cabs resulting in unhealthy working conditions for their operators. Noise is one of the detrimental factors. This study deals with determining and comparing the noise exposed on the operators of the combines with and without a cab used for wheat harvesting in Turkey. The sound pressure levels (dB) at octave band center frequencies (31.5–8000 Hz) and the sound levels (dBA) at the ear level of the operators were measured on 37 different combine harvesters with four different makes and different years from 1976 to 2001. Fifteen of the combines were without a cab, another 15 had original cabs while remaining seven combines had cabs mounted on them after manufacturing.

The sound pressure levels were in a decreasing trend from the lower frequencies to higher frequencies. This trend was more noticeable for the combines with original cab and with the cab mounted after manufacturing compared to the ones without cab. The use of a cab was more effective in the insulation of the noise at the medium and higher frequencies, which have more bothersome effect compared to the lower frequencies. The sound pressure levels were 75–102 dB and 46–89 dB at low (31.5–500 Hz) and high (500–8000 Hz) frequencies for all combines, respectively. The sound pressure levels at the frequency of 4000 Hz at which the human ear is most sensitive were 6–17 dB lower for the combines with the cabs mounted after manufacturing and 9–28 dB lower for the ones with the original cabs compared to the combines without cab. The sound levels were 85–90, 81–83, and 76–81 dBA for the combines without cab, with cab mounted after manufacturing, and with original cab, respectively.

The study showed that the use of a cab was useful in the insulation of the noise, particularly at higher frequencies. In addition, it protects the operator from the factors having detrimental effects on the working efficiency such as high temperature and dusty environment. The authors strongly recommend mounting of a cab on to the combines currently being used without a cab in rental system in Turkey to provide healthy working conditions for their operators.     

Monte Carlo Simulations of 17.9–22.3 MeV Energetic Proton Irradiation Effects on bcc-Zirconium Fusionic Materials

Advanced fusion structural materials (FSMs) have impact role in terms of efficiency of nuclear energy production. Besides engineering and design of fusion reactors, radiation durability of FSMs is another valuable issue that cannot be ignored. 17.9–22.3 MeV proton irradiation of bcc-Zirconium Fusion Structural Material was evaluated by using Monte Carlo based simulation tools. Total binary reaction cross sections were respectively calculated as 1167.6 and 1273.92 mb for 17.3- and 22.3 MeV proton energies via TALYS-1.6 version. Additionally, residual production cross sections and total particle production cross sections were obtained and analyzed by the TALYS code. Radiation damage parameters as Displacement Per Atom (DPA) and Stopping Power (SP) were studied by SRIM-2013 version. FLUKA 2011.1 used for only DPA calculations and making a complete comparison with the other calculation results. SP and Number of Secondaries were found by using GEANT4.10.p.04 version simulations. Natural Zr(p,x) reactions were studied in the given energy values in the plane of reaction probability and radiation damage calculations.     

33—THE SNARLING OF HIGHLY TWISTED MONOFILAMENTS. PART II: CYLINDRICAL SNARLING

An account is given of an experimental investigation of the cylindrical snarling of highly twisted monofilaments.

The theory underlying cylindrical snarling is set out, and an expression is derived for calculating the critical twist level at which normal snarling will be replaced by cylindrical snarling. Experiments on rubber filaments are described, and it is shown that there is good agreement between the theoretical and experimental results. Further experiments, in which the specimen was allowed to contract freely or forced into other forms, are also described.

It is shown from these experiments that it is difficult to establish the true equilibrium behaviour, since the situation appears to be dominated by frictional effects or by direct barriers to relative movement.     

32—THE SNARLING OF HIGHLY TWISTED MONOFILAMENTS. PART I: THE LOAD–ELONGATION BEHAVIOUR WITH NORMAL SNARLING

An account is given of an experimental investigation of the normal snarling of highly twisted monofilaments, those used being vulcanized rubber and nylon.

An earlier theoretical analysis is corrected, and the experimental results show that, after this correction, the theory put forward for the mechanical properties of the snarling mechanism holds reasonably well for elastic filaments. Although, as would be expected, there are larger deviations from the theory for viscoelastic filaments, the theory still gives a good indication of the behaviour of these filaments under torsion.     

Geobag Performance as Scour Countermeasure for Bridge Abutments

This paper presents observations and data from a sequence of laboratory experiments conducted to evaluate geobags as a countermeasure to protect bridge-abutment foundations from failure attributable to scour of the alluvial-river channel in which they are placed. Geobags comprise geotextile cloth bags filled with local sediment or concrete. The experiments focused on the performance of geobags placed as an apron around pile-supported wing-wall abutments retaining erodible embankments, and subject to live-bed and clear-water flow conditions. Though an apron of geobags is shown to substantially reduce or eliminate scour immediately at the abutment, the apron must be formed flexibly of linked geobags. Moreover, a performance concern is that the apron may shift scour to a location flanking or downstream of the apron, and in so doing imperil a nearby pier or riverbank. The experiments indicate the importance of protecting the embankment region beneath and immediately behind the abutment’s pile cap. Live-bed conditions proved to be the more critical for abutment protection, owing to the capacity of dunes to destabilize geobags around the edges of the apron. Design guidelines are given and include using current riprap configurations for sizing and placing geobags.     

The effect of niobium on the microstructure of ferritic stainless steel

The effect of different amounts of Nb and of homogenization on the ferritic stainless steels containing 17–18 wt.% Cr was investigated with scanning electron microscopy (SEM), optical microscopy, energy-dispersive spectrometry (EDS), X-ray diffraction (XRD) and differential thermal analysis (DTA). It was observed that M₂₃C₆, NbC and sigma phase formed in these steels. In addition, the formation of Nb₂C was observed in the sample containing 3.0 wt.% Nb. While the amount of Nb increased from 0.5 to 3.0 wt.% Nb, the microhardness of the matrix and the amount of M₂₃C₆ decreased and the toughness of the samples increased. After homogenization, the increase in the toughness of the samples containing 1.5–3.0 wt.%Nb was considerable and impressive.     

Barrier height temperature coefficient in ideal Ti/n-GaAs Schottky contacts

We have measured the I-V characteristics of Ti/n-GaAs Schottky barrier diodes (SBDs) in the temperature range of 60-320 K by the steps of 20 K. The SBDs have been prepared by magnetron DC sputtering. The ideality factor n of the device has remained almost unchanged between 1.02 and 1.04 from 120 to 320 K, and 1.10 at 100 K. Therefore, it has been said that the experimental I-V data are almost independent of the sample temperature and quite well obey the thermionic emission (TE) model at temperatures above 100 K. Furthermore, the barrier height (BH) Φ_b0 slightly increased with a decrease in temperature, 320-120 K. The Φ_b0 versus temperature plot from intercepts of the forward-bias ln I versus V curves has given a BH temperature coefficient of α = −0.090 meV/K. The Norde’s function has been easily carried out to determine the temperature-dependent series resistance values because the TE current dominates in the I-V characteristics. Therefore, the Φ_b0 versus temperature plot from the Norde’s function has also given a BH temperature coefficient value of α = −0.089 meV/K. Thus, the negligible temperature dependence or BH temperature coefficient close to zero has been attributed to interface defects responsible for the pinning of the Fermi level because their ionization entropy is only weakly dependent on the temperature.     

Poly(glycidyl methacrylate‐co‐3‐thienyl‐methylmethacrylate) based working electrodes for hydrogen peroxide biosensing

BACKGROUND: Hydrogen peroxide biosensors based on Poly(glycidyl methacrylate‐co‐3‐thienylmethylmethacrylate)/ Polypyrrole [Poly(GMA‐co‐MTM)/PPy] composite film were reported. Poly(GMA‐co‐MTM) including various amounts of GMA and MTM monomers was synthesized via the radical polymerization. Enzyme horseradish peroxidase (HRP) was trapped in Poly(GMA‐co‐MTM)/PPy composites during the electropolymerization reaction between pyrrole and thiophene groups of MTM monomer, and chemically bonded via the epoxy groups of GMA. Analytical parameters of the fabricated electrodes were calculated and are discussed in terms of film electroactivity and mass transfer conditions of the composite films. RESULTS: The amount of electroactive HRP was found to be 1.25, 0.34 and 0.213 µg for the working electrodes of Poly(GMA_30%‐ co‐MTM_70%)/PPy/HRP, Poly(GMA_85%‐co‐MTM_15%)/PPy/HRP and Poly(GMA_90%‐co‐MTM_10%)/PPy/HRP, respectively. Optimal response of the fabricated electrodes was obtained at pH 7 and an operational potential of ? 0.35 V. It was observed that effective enzyme immobilization and electroactivity of the composite films could be changed by changing the ratios of GMA and MTM fractions of Poly(GMA‐co‐MTM) based working electrodes. CONCLUSION: The amount of electroactive enzyme increases with increasing MTM content of the final copolymer. High operational stabilities of the biosensors can be attributed to the strong covalent enzyme linkage via the epoxy groups of GMA due to preventing enzyme deterioration and loss. A more convenient microenvironment for mass transfer was provided for the electrodes by higher GMA ratios. It is observed that mass transfer is dominated by the mechanism of electron transfer to obtain effective sensitivity values. This work contributes to discussions clarifying the problems regarding the design parameters of biosensors. Copyright © 2011 Society of Chemical Industry