Improving the Sensitivity of Superconductor-Based DC Magnetometer

In this study we report on some critical factors affecting the sensitivity of a magnetic field sensor whose working principle is based on a linear DC field dependence of the second harmonic of the AC response in polycrystalline type-II superconductors. DC-fields down to 2?nT in magnitude could be detected by finding optimal conditions. The optimal sensor design was determined by studying superconductor cores having different geometries and coil configurations. The optimal AC-field frequency, which is required for excitation of the specimen, was found to be 50?kHz. The second harmonic signal changes quite linearly with the DC-field up to 0.1?Oe.     

A novel strategy for cartilage tissue engineering: Collagenase-loaded cryogel scaffolds in a sheep model

In this study, we developed a novel strategy, through which cartilage tissue pieces were placed in a sheep cartilage defect model and covered with a collagenase incorporated cryogel scaffold (in vivo cartilage tissue engineering, IVCTE group). While applying this strategy, the chondrocytes could be isolated inside the body and the treatment could be accomplished in one session. To compare our strategy, to another group, in which we used cultured cells and Chondro-gide, standard matrix-induced autologous chondrocyte implantation (MACI) was applied. Although the MACI applied group demonstrated better healing than IVCTE, the type II collagen synthesis was better in the IVCTE group compared to MACI applied group. Collagenase did not have detrimental effect on surrounding cartilage in IVCTE group. The preliminary results of the novel strategy applied group (IVCTE) were promising.     

Synthesis and Characterization of Silicon Carbide Powders Converted from Metakaolin‐Based Geopolymer

Silicon carbide (SiC) ceramic powders were synthesized by carbothermal reduction in specific geopolymers containing carbon nanopowders. Geopolymers containing carbon and having a composition M₂O·Al₂O₃·4.5SiO₂·12H₂O+18C, where M is an alkali metal cation (Na⁺, K⁺, and Cs⁺) were carbothermally reacted at 1400°C, 1500°C, and 1600°C, respectively, for 2 h under flowing argon. X‐ray diffraction and microstructural investigations by SEM/EDS and TEM were made. The geopolymers were gradually crystallized into SiC on heating above 1400°C and underwent significant weight loss. SiC was seen as the major phase resulting from Na‐based geopolymer heated to ≥1400°C, even though a minor amount of Al₂O₃ was also formed. However, phase pure SiC resulted with increasing temperature. While a slight increment of the Al₂O₃ amount was seen in potassium geopolymer, Al₂O₃ essentially replaced cesium geopolymer on heating to 1600°C. SEM revealed that SiC formation and a compositionally variable Al₂O₃ content depended on the alkaline composition. Sodium geopolymer produced high SiC conversion into fibrous and globular shapes ranging from ~5 μm to nanosize, as seen by X‐ray diffraction as well as SEM and TEM, respectively.     

Project risk evaluation using a fuzzy analytic hierarchy process: An application to information technology projects

Projects are critical to the realization of performing organization's strategies. Each project contains some degree of risk and it is required to be aware of these risks and to develop the necessary responses to get the desired level of project success. Because projects' risks are multidimensional, they must be evaluated by using multi‐attribute decision‐making methods. The aim of this article is to provide an analytic tool to evaluate the project risks under incomplete and vague information. The fuzzy analytic hierarchy process (AHP) as a suitable and practical way of evaluating project risks based on the heuristic knowledge of experts is used to evaluate the riskiness of an information technology (IT) project of a Turkish firm. The means of the triangular fuzzy numbers produced by the IT experts for each comparison are successfully used in the pairwise comparison matrices. © 2006 Wiley Periodicals, Inc. Int J Int Syst 21: 559–584, 2006.     

Developing a group decision support system based on fuzzy information axiom

Information axiom, one of two axioms of axiomatic design methodology which is proposed to improve a design, is used to select the best design among proposed designs. In the literature, there are a lot of studies related to using of information axiom for the solution of decision making problems. Moreover, applications of information axiom have been increasing day by day. However, calculation procedure of information axiom is not only incommodious but also difficult for decision makers. In this paper, a decision support system (DSS) based on fuzzy information axiom (FIA) is developed in order to make this decision procedure easy. The developed system consists of a knowledge base module including facts and rules, inference engine module including FIA and aggregation method, and a user interface module including entrance windows. The main aim of this study is to present a DSS tool to help the decision makers to solve their decision problems by modifying data-base of the program. In this paper, an application procedure will be presented based on the optimal selection of location for emergency service to illustrate the implementation procedure of the proposed model.     

Malicious code detection in android: the role of sequence characteristics and disassembling methods

The acceptance and widespread use of the Android operating system drew the attention of both legitimate developers and malware authors, which resulted in a significant number of benign and malicious applications available on various online markets. Since the signature-based methods fall short for detecting malicious software effectively considering the vast number of applications, machine learning techniques in this field have also become widespread. In this context, stating the acquired accuracy values in the contingency tables in malware detection studies has become a popular and efficient method and enabled researchers to evaluate their methodologies comparatively. In this study, we wanted to investigate and emphasize the factors that may affect the accuracy values of the models managed by researchers, particularly the disassembly method and the input data characteristics. Firstly, we developed a model that tackles the malware detection problem from a Natural Language Processing (NLP) perspective using Long Short-Term Memory (LSTM). Then, we experimented with different base units (instruction, basic block, method, and class) and representations of source code obtained from three commonly used disassembling tools (JEB, IDA, and Apktool) and examined the results. Our findings exhibit that the disassembly method and different input representations affect the model results. More specifically, the datasets collected by the Apktool achieved better results compared to the other two disassemblers.

     

Investigation of porous polydimethylsiloxane structures with tunable properties induced by the phase separation technique

This article reports the fabrication and characterization of porous polydimethylsiloxane (PDMS) structures developed by the solvent evaporation-induced phase separation technique. Ternary systems containing water/tetrahydrofuran (THF)/PDMS with various concentrations are produced to form a stable solution. The porous PDMS structures are formed by removing the solvent (THF) and nonsolvent (water) phases during the stepping heat treatment procedure. The analytical ternary phase diagram is constructed based on the thermodynamic equilibrium state in the polymer solution to explain the stable/unstable formulations and the possible composition change path. The results show that the isolated pores with the adjustable pore size ranging from 330 to 1900 μm are obtained by tuning the water to the THF ratio. The mechanical properties of the porous PDMS structures are determined by conducting the tensile tests on the prepared dog bone-shaped specimens. A wide range of elastic modulus ranging between 0.49 and 1.05 MPa was achieved without affecting the density of the porous sample by adjusting the solvent and non-solvent content in the solution. It is shown that the flexibility of the porous structures can be improved by reducing the ratio of water to THF and decreasing the PDMS content. The porosity measurements reveal that the PDMS concentration is the major phase controlling the porosity of the structure, while the effect of water/THF is negligible.