The alteration degree of the metacrystalline rocks based on UAI,Bolu (Turkey)

The geomechanical properties of the metacrystalline rock masses vary due to alteration. The Devonian aged Yedigoller formation crops out in the Asarsuyu valley (Bolu, Turkey). The aim of this study is to investigate the alteration degree of the amphibolite and metagranodiorites based on their geomechanical and petrographical properties. The P-wave velocity is 1,613–5,588 m/s and the unconfined compressive strength varies between 12.75 and 99.86 MPa. Several weathering products occurred due to carbonisation, oxidation and sericitation. These rocks, subjected to hydrothermal effects, are classified as “fresh” to “completely altered” according to the unified alteration index (UAI). In addition, the values of the loss on ignition, modified weathering potential index and chemical index of alteration were taken into account for supporting the alteration process. Since the main process is hydrothermal alteration, the rocks which were exposed to alteration are weathered on the slopes after excavation. Weathering classification and the chemical indices indicate this process. Thus, UAI is concluded to be more suitable and credible in order to evaluate the hydrothermal alteration process of such crystalline rocks numerically.     

Investigation of thermal performance of a ground coupled heat pump system with a cylindrical energy storage tank

An analytical and computational model for a solar assisted heat pump heating system with an underground seasonal cylindrical storage tank is developed. The heating system consists of flat plate solar collectors, an underground cylindrical storage tank, a heat pump and a house to be heated during winter season. Analytical solution of transient field problem outside the storage tank is obtained by the application of complex finite Fourier transform and finite integral transform techniques. Three expressions for the heat pump, space heat requirement during the winter season and available solar energy are coupled with the solution of the transient temperature field problem. The analytical solution presented can be utilized to determine the annual variation of water temperature in the cylindrical store, transient earth temperature field surrounding the store and annual periodic performance of the heating system. A computer simulation program is developed to evaluate the annual periodic water and earth temperatures and system performance parameters based on the analytical solution. Copyright © 2003 John Wiley & Sons, Ltd.     

Colorimetric and fastness studies and analysis by reversed‐phase high‐performance liquid chromatography with diode‐array detection of the dyeing of silk fabric with natural dye Helichrysum arenarium

In this study, silk fabric samples were dyed by various procedures using Helichrysum arenarium extracts. Alum, ferrous sulfate, stanium chloride, calcium nitrate, and potassium bitartrate were used as mordants. Reversed‐phase high‐performance liquid chromatography with diode‐array detection was utilised for identification of the dyes present in the dyed silk fabrics and the plant extracts. The extraction of dyes was carried out with a hydrochloric acid/methanol/water (2:1:1 v/v/v) mixture. The colour coordinates and K/S values, as well as wash, light, and rub fastness, were determined.     

Determining Hounsfield Unit values of mortar constituents by computerized tomography

Computerized tomography was first developed in mid-1970 for medical purposes to non-destructively monitor the conditions of human tissues and bones. The idea was to detect the transmitted X-ray radiation emitted from multiple angles and to reconstruct the data as a tomographic image in an arbitrary unit known as Hounsfield Unit (HU) emerged in data processing phase. In this study, the same methodology was employed to obtain the HU values of sand and cement, which are two main components of mortar and concrete. Ranges of HU values were calculated for cement powder, hardened cement paste the sand in both dry and wet conditions.     

Free Vibration Analysis and Design of an Adhesively Bonded Corner Joint with Double Support

This study carries out the three dimensional free vibration analysis of an adhesively bonded corner joint and investigates the effect of an additional horizontal support to the adhesive corner joint with single support on the first ten natural frequencies and mode shapes. In the presence of a horizontal support the effects of the vertical support length, the adhesive thickness, the plate thickness, and the joint length on the natural frequencies and modal strain energies of the adhesive joint were also investigated using the back-propagation Artificial Neural Network (ANN) method and the finite element method. The natural frequencies and modal strain energies increased with increasing plate thickness, whereas an adverse effect was observed for increasing joint length. Both horizontal and vertical support lengths exhibited similar effects but the adhesive thickness had a negligible effect. The plate thickness and the joint length are dominant geometrical parameters in comparison with both horizontal and vertical support lengths. The proposed ANN models were combined with the Genetic Algorithm in order to determine the optimal corner joint in which the maximum natural frequency and minimum elastic modal strain energy are achieved for each natural frequency and mode shape of the adhesive corner joint and the optimal dimensions were given versus one geometrical parameter.     

An empirical model for kinetics of boron removal from boroncontaining wastewaters by the electrocoagulation method in a batch reactor

Boron removal from boron containing wastewaters prepared synthetically via the electrocoagulation method was studied. The experiments in which aluminum plate electrode was used were carried out in a batch reactor. The solution pH, initial boron concentration, current density, type of supporting electrolyte, temperature of solution and stirring speed were selected as experimental parameters. The obtained experimental results showed that efficiency of boron removal increased with increasing current density and decreased with increasing boron concentration in the solution. Supporting electrolyte had not significant effects on the percent of total boron removal. pH was very important parameter effecting boron removal and optimum pH was determined to be 8.0. This pH value reached an agreement with activity-pH diagrams for Al⁺³ species in equilibrium with Al(OH)₃ and boron species in aqueous media. As a result of increasing interaction between boron ions and dissolved aluminum ions in solution, the increasing solution temperature increased boron removal efficiency. Increasing stirring speed decreased boron removal efficiency where the increasing stirring speed decreased the capability of floc formation of aluminum ions. As a result, it was seen that about 99% of boron in the wastewater could be removed at optimum conditions. In addition, the process kinetics was predicted by using heterogeneous fluid–solid reaction models. It was seen statistically that the kinetics of this process agreed with the pseudo-second-order model as follows: X_B/(l−X_B) = 18,241[OH][C]^−3.45[CD]^7.79[t]^1.41[S]^−3.65exp[−30,668/RT].     

A Study of Complexation-ability of Neutral Schiff Bases to Some Metal Cations

The constants of the extraction equilibrium and the distribution for dichloromethane as an organic solvent having low dielectric constant of metal cations with chiral Schiff bases, benzaldehydene-(S)-2-amino-3-phenylpropanol (I), ohydroxybenzaldehydene-( S)-2-amino-3-phenyl-propanol (II), benzaldehydene-(S)-2- amino-3-methylbutanol (III) with anionic dyes [4-(2-pyridylazo)-resorcinol mono sodium monohydrate (NaPar), sodium picrat (NaPic) and potassium picrat (KPic)] and some heavy metal chlorides were determined at 25 ºC. All the ligands have given strongest complexation for NaPar. In contrast, similar behaviour for both alkali metal picrates is not apparent in the complexation of corresponding ligands.     

Logarithmic based robust approach to parametric uncertainty for control of robot manipulators

In this paper, a new robust control law for controlling robot manipulators with parameter uncertainty is presented. A controller is designed based on the Lyapunov function and the control law that guarantees the system stability is derived as a result of analytical solution. Apart from previous studies, uncertainty bound and adaptation gain matrix are determined using the estimation law to control the system properly, and so this estimation law is developed as a logarithmic function depending on robot kinematics inertia parameters and tracking error. An application of the proposed control input to a two‐link robot manipulator is presented and numerical simulations are included. Copyright © 2005 John Wiley & Sons, Ltd.     

Modelling of Bound Estimation Laws and Robust Controllers for Robustness to Parametric Uncertainty for Control of Robot Manipulators

In this paper, first, a new approach is proposed for derivation of bound estimation laws for robust control of robot manipulators. In this approach, functions depending on robot kinematics and control parameters and integration techniques can be used for derivation of the bound estimation laws based on the Lyapunov theory, thus, stability of the uncertain system is guaranteed. Five new bound estimation laws are proposed, and in this derivations, five novel functions depending on robot kinematics and control parameters and proper integration techniques, such as substitution method, integration by part and integration by partial fractions are used. Then, four new robust control inputs are proposed based on each derived bound estimation law. Lyapunov theory based on Corless and Leitmann (IEEE Trans Automat Contr 26:1139–1144, 1981) approach is used for designing the robust control input achieving uniform boundedness error convergence. This study also allows derivation of other bound estimation laws for robust controllers provided that appropriate novel functions and proper integration techniques are chosen.     

Exploring Engineering Graduate Student Research Proficiency with Student Surveys

Background Research is considered the essence of graduate engineering education, but knowledge about the engineering graduate student research experience is scarce in literature. Some studies that examine graduate engineering education suggest that students are experiencing educational deficiencies that can affect the research experience. Thus, exploring engineering graduate student research proficiency is warranted. Purpose (Hypothesis ) This work begins to earnestly answer the research questions “How proficient are engineering graduate students in research?” and “What factors affect the research proficiency of these students?” Design /Method In order to answer the two research questions specifically for the Georgia Institute of Technology Environmental Engineering graduate program, current students in the program participated in two surveys. Survey questions were designed to measure students' perceptions of their research proficiency and to aid in determining student academic motivations tied to proficiency. Results Many students indicated that they lacked research preparation upon beginning graduate study and during the first year of study, lacked development in important research skills like statistics and communicating in writing, and were somewhat hindered in research organization and progress. Regarding academic motivations, students generally valued personal advancement and enrichment over paper publication. Doctoral students overall indicated more preparation with respect to several aspects of research and more value placed on paper publication than did master's students. Conclusions The surveys provided important findings regarding student research proficiency for the engineering graduate program in question. These findings encourage the exploration of engineering graduate student research proficiency on a broader scale in future studies.