Analysis,design, and optimization of structures with integral compliant mechanisms for mid‐frequency response

A multi‐scale paradigm is proposed that utilizes periodic, small‐scale, integral compliant mechanisms within larger‐scale structures for the attenuation of vibro‐acoustic response. Amplification principles serve as the basis for the design of these mechanisms in achieving reduced energy transmission. The spectral finite element method is exploited for a force–velocity and energy flow analysis of the resultant truss‐like structures. A genetic algorithm is employed to optimize structure size for greatest effectiveness in the frequency range of interest. This study demonstrates that a significant decrease in structural vibration is achievable and suggests promising applications including the design of acoustic isolation panels for broadband vehicle noise reduction. Copyright © 2007 John Wiley & Sons, Ltd.     

Enterprise knowledge management model: a knowledge tower

One of the most important aspects of knowledge management (KM) is to create a system that is capable of providing mechanisms and methodologies allowing the right knowledge to be at the right place and at the right person as well as at the right time within an enterprise. There have been several models developed for this purpose. The main objectives of these models are to organize the knowledge activities to increase competitive advantage and turn the market share into a continuous and permanent superiority through utilizing the intellectual capital of the enterprise for better products and services. When existing models are carefully analyzed, it can be clearly seen that every model addresses different aspects of KM. While some of these models have been intensifying on the use of technology and production of knowledge, the others rather focus on the utilization of knowledge itself. Although these models point out the importance of managerial participation, they are mainly designed to be facilitated at operational levels. It is now obviously seen that there is a need for a new model that will deal with KM at strategic, tactic, and operational levels in an integrated manner. In this study, an enterprise knowledge management model (EKMM) is developed to facilitate this. The model is also called the “Knowledge Tower” due to its dynamics and tower-like infrastructure. EKMM does not only deal with utilizing the knowledge but also create KM strategies, knowledge culture as well as respective leveraging activities. It provides an extensive assessment capability to make sure that the KM practices are carried out as effectively as possible. This surely helps identifying the lack of implementations and areas requiring improvements.     

Synthesis and characterization of Schiff base derivative with pyrrole ring and electrochromic applications of its oligomer

In this study, Schiff base monomer, 2-[(1H-pyrrol-2-yl-methylene)amino]phenol (2-PMAP) was obtained by condensation reaction of 2-aminophenol with pyrrole-2-carbaldehyde. This monomer was oxidized in an aqueous alkaline medium by NaOCl to obtain the corresponding oligomer (O-2-PMAP). The resulting compounds were characterized by ¹H- and ¹³C-NMR, FT-IR, UV–vis, TG-DTA and size exclusion chromatography (SEC) techniques. Metal complexes compounds of O-2-PMAP were prepared with various metal salts, such as Cu (AcO)₂·H₂O, Zn (AcO)₂·2H₂O, Cd (AcO)₂·2H₂O, Pb (AcO)₂·3H₂O and Co (AcO)₂·4H₂O. In addition to this, electrochemical copolymerization of O-2-PMAP with thiophene (Th), 3,4-ethylenedioxythiophene (EDOT) and pyrrole (Py) were performed onto indium/tin oxide (ITO)-coated glass plate. The spectral changes of the co-polymeric films were recorded in the range of the different potentials. The film stabilities of its EDOT and Py copolymers were determined. Consequently, it was realized that the copolymer films kept their stability for a long time.     

An effective synthesis route for improving the catalytic activity of carbon-supported Co–B catalyst for hydrogen generation through hydrolysis of NaBH4

A novel method for synthesis of carbon-supported cobalt boride catalyst was developed for hydrogen generation from catalytic hydrolysis of NaBH₄ solution. The activated carbon and carbon black supported catalysts prepared by “reduction–precipitation” method were found to be much more active than those prepared by conventional “impregnation–reduction” method inspite of the same Co content. A maximum hydrogen generation was achieved using carbon black supported Co–B, which lowers the activation energy to 56.7 kJ mol⁻¹. The effects of NaOH concentration (1–15 wt.%), NaBH₄ concentration (5–20 wt.%) and reaction temperature (25–40 °C) on the performance of the most active catalyst (Co–B/C_B) were investigated in detail. The results indicated that this catalyst can be used in a hydrogen generator for mobile applications such as PEMFC systems due to its high catalytic activity and simple preparation method.     

Fuzzy logic and statistical-based modelling of the Marshall Stability of asphalt concrete under varying temperatures and exposure times

In this study, the Marshall Stability (MS) of asphalt concrete under varying temperature and exposure times was modelled by using fuzzy logic and statistical method. This is an experimental study conducted using statistics and fuzzy logic methods. In order to investigate the Marshall Stability of asphalt concrete based on exposure time and environment temperature, exposure times of 1.5, 3, 4.5 and 6 h and temperatures of 30, 40 and 50 °C were selected. The MS of the asphalt concrete at 17 °C (in laboratory environment temperature) was used as reference. The results showed that the MS of the asphalt core samples decreased 40.16% at 30 °C after 1.5 h and 62.39% after 6 h. At 40 °C the decrease was 74.31% after 1.5 h, and 78.10% after 6 h. At 50 °C the stability of the asphalt decreased 83.22% after 1.5 h, 88.66% after 6 h. The relationships between experimental results, fuzzy logic model and statistical results exhibited good correlation. The correlation coefficient was R = 0.99 for fuzzy logic model and R² = 0.9 for statistical method. Based on the results of the study, it could be said that both the fuzzy logic method and statistical methods could be used for modelling of the stability of asphalt concrete under varying temperature and exposure time.     

Adaptive neuro-fuzzy inference approach for prediction the stiffness modulus on asphalt concrete

In this study, stiffness modulus parameters of asphalt concrete were determined experimentally for different temperature and exposure times. The stiffness modules were calculated according to Nijboer stiffness module. Basic physical properties and the quantity of bitumen of asphalt core samples were designated for determining the stiffness modules. The samples were exposed to 17 °C (reference temperature), 30, 40 and 50 °C temperatures for 1.5, 3, 4.5 and 6 h respectively and then Marhall Stability tests were done for each samples. By using the test results a prediction model with Sugeno type based on the adaptive neuron-fuzzy inference system (ANFIS) was alternatively developed to predict the stiffness modules of asphalt core samples. As a result, it was seen that the developed prediction model could be used as a prediction model for unperformed situations which are not suitable for experiments.     

Effect of steaming time on surface roughness of beech veneer

The objective of this study was to investigate effect of steaming time on surface roughness of beech (Fagus orientalis L.) veneer produced using the rotary cutting method. Three roughness parameters, average roughness (R_a), mean peak-to-valley height (R_z), and maximum roughness (R_max) obtained from a stylus type profilometer were used to evaluate the roughness of the veneer sheets. Surface roughness of the samples cut from the inner portion of the logs showed a significant dependence on steaming time. Among the specimens 20 h steaming time showed the smoothest surface . Surface roughness of veneer samples taken from both outer and middle portion of the logs did not show any statistically significant difference as steaming time was changed. Based on the findings in this study, it appears that steaming time should be approximately 20 h to have an ideal surface quality of the veneer with a minimum cost of production.     

KB-SCHED: Knowledge-based scheduler for complex and dynamic systems

Scheduling problems are becoming more and more complex everyday. This makes the current rules and algorithms difficult to comply with the requirements. New machines with the capabilities of processing more than one jobs is being developed. Sometimes one job is divided into parts and processed by more than one machine at the same time. These make the current algorithms insufficient. Artificial intelligence technologies, especially expert systems are proven to deal with such dynamic complex problems in several domains. In this study, an example of such a complex problem is introduced and knowledge-based scheduling for these kind of problems is elaborated with a real life industrial example.     

The Seebeck coefficient of the solid and liquid germanium

The knowledge of the Seebeck coefficient of materials is essential in determining the actual solid/liquid interface temperature during the melt growth of crystals. In this study, the Seebeck coefficient of the solid and liquid germanium was measured employing the small Δ T technique. The Seebeck coefficient increased from −107 μ V/^∘C at 857^∘C to −54 μ V/^∘C at 931^∘C in the solid. However, an average constant value of −0.6 μ V/^∘C was obtained in the liquid from 938 to 960^∘C, above which a value of −18 μ V/^∘C was recorded. Also, when the liquid samples were cooled below the melting point, a melt supercooling was observed, which seemed to be larger with higher melt temperatures.