Optimum design of multiple positioned tuned mass dampers for structures constrained with axial force capacity

The stories of structure may have different and limited axial force capacity. In order to passively control the translational movement of structures, a tuned mass damper (TMD) positioned on a story may cause to exceed axial force capacity of a story. The optimum performance is achieved when all additional masses are positioned on the top story. Whereas, the top stories of structure may be constructed with lower axial force capacity than the lower stories. In that case, the maximum allowed TMD mass for upper stories may be low. In that situation, several TMDs may be positioned on several stories. In the current study, the optimum tuning of TMDs positioned on multiple stories of structure is investigated. By using small masses, it is also possible to obtain effective passive control with dampers that have small damping coefficients comparing with a single TMD on the top of the structure. The design variables of the optimization problem such as the period and damping ratio of TMD are tuned according to a metaheuristic algorithm called flower pollination algorithm. The TMD is optimized for near‐fault excitations by using impulsive motions during the optimization process. The proposal was applied to four case studies. According to the results, the multiple positioned TMDs may be a practical and effective option comparing with the use of a single heavy TMDs on the top of a structure.     

Removal copper,chromium and arsenic from CCA-treated yellow pine by oleic acid

Removal of Cu, Cr and As metals from chromated copper arsenate (CCA) treated yellow pine wood samples with three different dimensions were investigated by extraction with oleic acid at four different pH levels. The concentrations of Cu, Cr and As were determined by XRF. The effects of pH, dimension and duration on remediation of CCA-treated wood samples were determined. Oleic acid was found to be very effective to remove copper, chromium and arsenic from CCA-treated wood samples especially at lower pH levels (pH=2.00 and 2.50). In addition, the best models estimate copper, chromium and arsenic leaching from CCA-treated wood samples by oleic acid remediation were determined by step-wise regression analysis.     

Technoparks and Technology Transfer Offices as Drivers of an Innovation Economy: Lessons from Istanbul's Innovation Spaces

Universities can significantly contribute to the regional development and innovation capability of a city if the knowledge produced in universities can be appropriately cycled back to the city in the form of technological innovation. Technology parks and technology transfer offices (TTOs), as urban knowledge and innovation spaces, are two important channels of building research platforms with enterprises where universities can disseminate knowledge. While technology parks create space for knowledge generation and innovation within a city, university TTOs play a critical role in enhancing knowledge spillover and creating new start-up firms. This paper highlights the contribution universities can make to Istanbul's potential of becoming an innovative city that houses successful urban knowledge and innovation spaces. By conducting interviews with the managers of technoparks and TTOs in Istanbul, we explore how the existence of technoparks and TTOs within a university affects the success of technology-transfer mechanisms.     

Climatic effect in the formation of vernacular houses in the Eastern Black Sea region

Climate is one of the many factors such as socio-cultural structure, economy, materials, and technology that influence architectural forms. The resolutions that exist as a result of the effect of climate on architecture differ according to regions, cultures, time and technology. The climate in the Eastern Black Sea region, which lies in the north of Turkey, plays an active role in the formation and diversity of the vernacular houses in the region. Climatic factors such as rain, wind, humidity and sunlight in the region, which has a warm-humid climate and which gets excessive rain, have different effects on the spaces, elements and annexes of the vernacular houses. This study explains climatic approaches that are evident in the architecture of the vernacular houses in the Eastern Black Sea region. The aim of this study is to give information about the vernacular architecture in the Eastern Black Sea region and to investigate the relationship between the architectural products and the climate that plays a very important role in the formation of this architecture. Thus, the effects of climatic factors, such as rain, wind, humidity and sunlight, on vernacular houses are explained in the topics as plan, external walls, roof and exterior of buildings.     

Cost and safety optimization of structural design specifications

The design of buildings, bridges, offshore platforms and other civil infrastructure systems is controlled by specifications whose purpose is to provide the engineering principles and procedures required for evaluating the safety of structural systems. The calibration of these codes and specifications is a continuous process necessary to maintain a safe national and global infrastructure system while keeping abreast of new developments in engineering principles, and data on new materials, and applied loads. The common approach to specification calibration is to use probabilistic tools to deal with the random behavior of materials and to account for the uncertainties associated with determining environmental and other load effects. This paper presents a procedure to calibrate load factors for a structural design specification based on cost and safety optimization. The procedure is illustrated by determining load factors that may be applicable for incorporation in a bridge design specification. Traditional code calibration procedures require a set of pre-determined safety levels that should be used as target values that each load combination case should satisfy. The procedure in this paper deduces the failure cost implied in present designs, and provides consistent safety levels for all load combination cases. For greater accuracy, load effects showing variance in time have been modeled by separating them into two random variables; time dependent r.v. (wind speed, vehicular loads, etc.) and time independent r.v. (modeling uncertainties). The total expected lifetime cost is used in the optimization to account for both initial construction cost and future equivalent failure costs.     

Spectroscopic,thermal, and mechanical characterization of carboxyl-terminated polybutadiene-based carbon black-filled networks

Carbon black-filled and unfilled carboxyl-terminated polybutadiene (CTPB) networks were prepared by using two types of reactive systems at different reactive group ratios to be applied to the solid propellant motor case as a liner. For the preparation of CTPB networks, tris(2-methyl-1 aziridinyl)phosphine oxide (MAPO) and a mixture of liquid bisphenol A-epichlorohydrin (Epikote-828) and MAPO were used as two different reactive systems. The chemistry and thermal stability of the CTPB networks were followed by Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TG) techniques, whereas mechanical and adhesive properties were tested by tensile measurements. The mixed reactive system caused a modification in the ultimate tensile stress and elongation-at-break properties, adhesive properties, and thermal stability of the CTPB networks. It was understood that this modification was due to the inter- and intramolecular bridge formation via the end-linking reaction of Epikote-828 with amine groups of the former network chains. The combination of MAPO with Epikote-828 also imparted better peel and lap-shear strength properties to the CTPB elastomers. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 355–366, 1997     

Adjustment of Cell Adhesion on Polyurethane Structures via Control of the Hard/Soft Segment Ratio

Creating substrates with a similar composition that can either prevent or promote cell adhesion is still a challenging feat. Here, it is shown that a strikingly simple method of tuning the amount of hard segments or isocyanate index (NCO_ind) of a polyurethane (PU) film allows to modulate cell adhesiveness. PU films are synthesized with NCO_ind of 75, 100, 200, 300 and 400 corresponding to ratios of isocyanate to hydroxyl functions of 0.75, 1, 2, 3, 4, respectively. The adhesive capacity of NIH 3T3 fibroblasts (3T3) and Wharton's jelly mesenchymal stem cells (WJMSCs) are dependent on the NCO_ind. For NCO_ind below 300, no cell adhesion can be observed regardless of the cell type, whereas for NCO_ind of 300 and 400 cells adhere to the PU surface. WAXS and small angle X‐ray scattering (SAXS) studies reveal that variations of NCO_ind allows to modulate the phase separation in PU films. Porod's law shows that for NCO_ind of 300 and 400, the hard–soft segment interface is sharp. Conversely, samples with smaller NCO_ind present diffuse interfaces. Hence, the morphology of the interface between hard and soft domains appears to be a critical feature that correlates with the adhesion capacity of cells.     

Thermal insulation and thermal contact properties of wool and wool/PES fabrics in wet state

The most important parameters characterizing thermal comfort of special garments are thermal resistance and water vapor permeability. Contrary to common textiles, protective garments are often used in wet state, which affects their comfort properties. However, current measuring instruments mostly do not enable reliable measurement of wet fabrics. In the article, Alambeta instrument was used, which provides reliable measurement of thermal comfort of dry and wet fabrics. Research program included evaluation and discussion of the thermal properties: conductivity, resistance, and absorbtivity of wool and wool/partial use of hydrophobic fibers woven fabrics in dry, standard, and wet states. The effect of composition on the above-mentioned properties of these fabrics has also been investigated.     

Rational Engineering of Hydratase from Lactobacillus acidophilus Reveals Critical Residues Directing Substrate Specificity and Regioselectivity

Enzymatic conversion of fatty acids (FAs) by fatty acid hydratases (FAHs) presents a green and efficient route for high-value hydroxy fatty acid (HFA) production. However, limited diversity was achieved among HFAs, to date, with respect to chain length and hydroxy position. In this study, two highly similar FAHs from Lactobacillus acidophilus were compared: FA-HY2 has a narrow substrate scope and strict regioselectivity, whereas FA-HY1 utilizes longer chain substrates and hydrates various double-bond positions. It is revealed that three active-site residues play a remarkable role in directing substrate specificity and regioselectivity of hydration. If these residues on FA-HY2 are mutated to the corresponding ones in FA-HY1, a significant expansion of substrate scope and a distinct enhancement in hydration of double bonds towards the ω-end of FAs is observed. A three-residue mutant of FA-HY2 (TM-FA-HY2) displayed an impressive reversal of regioselectivity towards linoleic acid, shifting the ratio of the HFA regioisomers (10-OH/13-OH) from 99:1 to 12:88. Notable changes in regioselectivity were also observed for arachidonic acid and for C₁₈ polyunsaturated fatty acid substrates. In addition, TM-FA-HY2 converted eicosapentaenoic acid into its 12-hydroxy product with high conversion at the preparative scale. Furthermore, it is demonstrated that microalgae are a source of diverse FAs for HFA production. This study paves the way for tailor-made FAH design to enable the production of diverse HFAs for various applications from the polymer industry to medical fields.     

Order picking in parallel-aisle warehouses with multiple blocks: complexity and a graph theory-based heuristic

In this paper, we consider the order picking problem (OPP), which constitutes one of the special cases of the Steiner travelling salesperson problem and addresses the costliest operation in a warehouse. Given a list of items to be picked and their locations in the warehouse layout, the OPP aims to find the shortest route that starts from a depot point, picks all the items in the list, and returns to the depot. This paper fills two important gaps regarding the OPP. First, to the best of our knowledge, we present the first complexity results on the problem. Second, we propose a heuristic approach that makes use of its graph-theoretic properties. Computational experiments on randomly generated instances show that the heuristic not only outperforms its state-of-the-art counterparts in the literature, but it is also robust in terms of changing problem parameters.