Rule-based automatic segmentation of color images

A rule-based segmentation algorithm for color images has been presented in this paper. The proposed strategy is similar to region growing algorithm where the seed points are automatically selected and grown. The similarity percents of neighboring pixels are calculated by means of fuzzy reasoning rules, and the merging of the pixels with regions is performed by comparing the similarity percent with the similarity threshold value. The algorithm does not require any prior knowledge of the number of regions existing in the image and decreases the computational load required for the fuzzy c-means (FCM). Several computer simulations have been performed and the results have been discussed. The simulation results indicate that the proposed algorithm yields segmented color image of perfect accuracy.     

Graphene reknits its holes

Nanoholes, etched under an electron beam at room temperature in single-layer graphene sheets as a result of their interaction with metal impurities, are shown to heal spontaneously by filling up with either nonhexagon, graphene-like, or perfect hexagon 2D structures. Scanning transmission electron microscopy was employed to capture the healing process and study atom-by-atom the regrown structure. A combination of these nanoscale etching and reknitting processes could lead to new graphene tailoring approaches.     

An experimental study on the linear differential scattering coefficients of the Trommel Sieve Waste (TSW)

The linear differential scattering coefficients (LDSCs) at 60 keV are measured for TSW at seven angles ranging from 60° to 120° at intervals of 10°. The results are compared with relativistic and non-relativistic theoretical values. The purpose of this work is to seek evidence whether there is a relationship between the LDSC and the scattering angle. This is the first time the LDSCs have been measured at energies lower than 100 keV, so there is a lack of comparable findings reported in the literature.     

Electricity production opportunities from multipurpose dams (case study)

The hydropower is the leading source of renewable energy. It provides more than 97% of all electricity generated by renewable sources. The main advantage of hydro systems is elimination of the cost of fuel. Hydropower on a small-scale is in most cases “run-of-river”, with no dam or water storage, and is one of the most cost-effective and environmentally benign energy technologies to be considered both for rural electrification in less developed countries and further hydro developments in Europe. Multipurpose dams, like Porsuk Dam in Eskisehir, are constructed with the aim of supplying domestic, irrigation and industrial water except electricity generation. Porsuk basin has suitable valley in upstream of existing Porsuk Dam for realizing of small reservoirs. The discharge capacity of Porsuk River is appropriate only to install Small Hydropower Plants (SHPs). For the sustainable management of Porsuk River water, except existing Porsuk Dam, it is required to construct a few new dams on this river. The valley of Porsuk River is suitable to construct concrete faced rockfill dams (CFRDs). For this propose, initially, historical data of inlet and outlet of Porsuk reservoir has been investigated. Historical data have been analyzed on a monthly basis for 32 years. It has been calculated that the electricity generation using this potential is 20.69 GWh/year with 4.2 MW installed capacity from Porsuk Dam. For the evaluation of all the Porsuk River water potential, it is required constructing at least two new dams in the hilly Porsuk basin. It is calculated that the total electricity generation from these two will reach up to 37.79 GWh/year with 2×2.8 MW installed capacity.     

Geomechanical properties of the ophiolites (Çankiri/Turkey) and alteration degree of diabase

The alteration state of magmatic rocks is significant in the organization of stability, excavation methods, bearing capacity and engineering applications in civil engineering works for dam construction and basement rock analysis. For this reason, alteration needs to be defined by reliable, controllable and easily applicable methods, and expressed in numerical values. As an example the geomechanical properties of Çankiri serpentinite, gabbro, and diabase have been investigated during a study for determining a dam axis location, and P-wave velocity variation, uniaxial strength, water absorption ratio of diabase determined, all of which were later evaluated under the “unified alteration index” concept, described by the author. Mathematical equations were outlined by regression analysis of the results. Thus, an approach could be achieved to various geomechanical properties and alteration states of the rock, starting with known properties. A relationship such as: Edd=2.942–0.834 Log_e Kc (×10⁵ kg/cm²) was finally established between the dry dynamic elasticity modulus (Edd) and unified alteration index (Kc). Alteration degree can be calculated at a rate as high as 95 % significance, by using the above equation with easily obtainable dynamic elasticity modulus values.     

A numerical study of the influence of bump type triggers on the axial crushing of top hat thin-walled sections

This paper deals with the issue of a trigger design and its performance. In this respect, a numerical investigation is carried out to study the effects of the geometrical features of a bump type trigger on the crush behavior of an energy absorbing member subjected to axial impact loading. The member was constructed by joining a top hat profile with a flat lid. The trigger was considered to be a bump with a semi-circular cross section on the hat profile. The finite element solver, LS-DYNA was used in all crush simulations. As a result, the introduction of the trigger was found to be effective on the peak crush force and the energy absorption capability of the member under axial impact loading. It was also shown that the crush response could be controlled by varying the location and the geometry of the trigger.     

Hilbert transformation of waveforms to determine shear wave velocity in concrete

Given the density value, elastic properties of a homogeneous and isotropic material can be determined provided that primary and shear wave (P- and S-wave) velocities are known. P-waves are easier to monitor and detect compared to the S-waves. In concrete, along with P-wave velocity, shear wave velocity measurement is important in determining the elastic properties. These elastic properties could be implemented in assessing the quality of in-situ concrete. After an extensive literature survey, this study focused on the applicability of Hilbert transformation of waveforms to determine shear wave velocity in concrete material. The experimental work consisted of a set of ultrasonic measurements on the surface of a reinforced concrete deck. The recorded waveforms were then analyzed to obtain the arrival times of P- and S-waves. Hilbert transformation of the waveforms proved to yield reliable and repeatable results.     

Free Vibration Analysis of an Adhesively Bonded Functionally Graded Tubular Single Lap Joint

In this study, the three-dimensional free vibration analysis of an adhesively bonded functionally graded tubular single lap joint was carried out using the finite element method. The functionally graded tubes of the adhesive joint are composed of ceramic (Al₂O₃) and metal (Ni) phases varying through the tube thickness. The adhesive material properties, such as modulus of elasticity, Poisson's ratio, and density were found to have negligible effect on the first ten natural frequencies and mode shapes of the adhesive joint. The optimal design parameters of the adhesive joint, such as overlap length, inner radius of the inner tube, outer and inner tube thicknesses, and the through-the-thickness material composition variation were searched using both the artificial neural networks (ANNs) and the genetic algorithms (GAs). For this purpose, the natural frequencies and modal strain energy values were calculated for an adhesive joint with random geometrical properties and material compositions through the tube thicknesses, and were used for training the proposed artificial neural network models. The outer tube thickness, the inner tube-inner radius, and the compositional gradient exponent had considerable effect on the natural frequencies, mode shapes, and modal strain energies of the functionally graded tubular single lap joint, whereas the overlap length and the inner tube thickness had a minor effect. The GAs integrated with ANNs was employed to determine optimal design parameters satisfying both maximum natural frequency and minimum modal strain energy conditions for each natural mode of the tubular adhesive joint.