Synthesis and characterization of soluble multi-walled carbon nanotube/poly(organophosphazene) composites

Poor solubility of carbon nanotubes (CNTs) in water and organic solvents offers a significant problem for their applications. Macromolecules can be suitable solubilizing agents and a structural component of composite materials for CNTs. Several polymers were tested for the preparation of CNT dispersions. In this study, a poly[(4-pyridineoxy)(phenoxy)phosphazene] (3) was prepared by sequential treatment of poly(dichlorophosphazene) (2) with sodium 4-pyridineoxy and sodium phenoxide in THF. Multi-walled carbon nanotube/poly(organophosphazene) composites (f-MWCNT/PZS) with different feed ratios [R_feed = 1:1, 1:3, 1:5 and 1:10 (w/w)] were obtained by the treatment of the functionalized multi-walled carbon nanotube (f-MWCNT) with the protonated poly(organophosphazene) (PZS). Excellent dispersions of the f-MWCNT/PZS nanocomposites in water and common organic solvents were achieved. The influence of feed ratio on polymer coating and the stability of composites were investigated by thermal gravimetric analysis (TGA). f-MWCNT/PZS_1:5 nanocomposite was characterized by ³¹P, ¹H NMR, FTIR, XRD, EDX and Raman Spectroscopy. The morphologic characterizations of f-MWCNT/PZS_1:5 were carried out by HRTEM and SEM methods.     

Dosage planning for type 2 diabetes mellitus patients using Indexing HDMR

Diabetes mellitus type 2 (T2DM), is also named as non-insulin dependent diabetes mellitus (NIDDM) or adult-onset diabetes, is a metabolic disease characterized by high blood glucose. Deficient insulin production or insulin resistance of the body are the causes of T2DM. Drug treatment has a very important role as well as exercise and diet. To keep the body sugar level stable within the accepted range values, drug dosage planning is a part of combinational treatment. In this study, Indexing HDMR method which is a multivariate data partitioning method is used to produce a polynomial based rule structure to manage the drug dosage planning process. For this purpose, 142 diabetic assays, 96 of which as training data and 46 of which as testing data, were used in this study. The Indexing HDMR method worked well in modeling drug dosages and it is obvious that the method is reliable for the purpose.     

A direct touch table-top display as a multi-user information kiosk: Comparing the usability of a single display groupware either by a single user or people cooperating as a group

This study aimed to investigate the usability of a direct touch table-top display (D3TD) application that was designed to be used as a multi-user information kiosk (MUIK). We examined its use by either a single person or multiple user groups to determine the effect of people cooperating as a group on its usability. We compared both groups’ user performance and usability survey results. A one-way MANOVA of overall usability metrics emphasised a significant difference between the groups. Given the significance of the overall test, examining the univariate main effects revealed that the difference between the groups arose in the earlier system use stages due to differences in the success rate. There was no difference in the task completion time between the groups. Participants in the multiple user group achieved a higher task completion rate in the first phase and lower error rates in the following steps. However, the usability survey results did not reveal a significant difference between the groups. We observed that users working on the same individual task tended to help each other when working in a multi-user environment. These mutual aids occurred mostly in the earlier stages, influencing the users’ performance. The results show that a D3TD has a potential to enhance usability in terms of effectiveness when deployed as a MUIK.     

Cyber victim and bullying scale: A study of validity and reliability

The purpose of this study is to develop a reliable and valid scale, which determines cyber victimization and bullying behaviors of high school students. Research group consisted of 404 students (250 male, 154 male) in Sakarya, in 2009–2010 academic years. In the study sample, mean age is 16.68. Content validity and face validity of the scale was provided via field specialists’ judgment. Confirmatory and exploratory factor analyses were performed for investigation of the factor structure of the scale. As a result of principal component analysis of cyber victim subscale three factors emerged which accounted for the 46.38% of the total variance. Also for cyber bullying subscale, same three factors emerged accounting for the 49.18% of the total variance. Scales with 22 items under 3 factors were tested with confirmatory factor analysis for each victim and bullying variables. Three factors were named as cyber verbal bullying, hiding identity and cyber forgery. Three factors model of scales were found theoretically and statistically fitted after confirmatory factor analysis. For criterion related validity the correlation between cyber victim and bullying scale and Aggression Scale was calculated as .27 and .36, respectively. The internal consistency coefficients calculated for reliability. Cyber victim and bullying scales’ internal consistency coefficients were .89 and split-half coefficients were .79. for both scales. Test-retest reliability for cyber victim .85, for cyber bullying respectively .90 was found. These results demonstrate that the Cyber Victim and Bullying Scale’ is a valid and reliable instrument.     

Effect of Using Thorium Molten Salts on the Neutronic Performance of PACER

Utilization of nuclear explosives can produce a significant amount of energy which can be converted into electricity via a nuclear fusion power plant. An important fusion reactor concept using peaceful nuclear explosives is called as PACER which has an underground containment vessel to handle the nuclear explosives safely. In this reactor, Flibe has been considered as a working coolant for both tritium breeding and heat transferring. However, the rich neutron source supplied from the peaceful nuclear explosives can be used also for fissile fuel production. In this study, the effect of using thorium molten salts on the neutronic performance of the PACER was investigated. The computations were performed for various coolants bearing thorium and/or uranium-233 with respect to the molten salt zone thickness in the blanket. Results pointed out that an increase in the fissile content of the salt increased the neutronic performance of the reactor remarkably. In addition, higher energy production was obtained with thorium molten salts compared to the pure mode of the reactor. Moreover, a large quantity of ²³³U was produced in the blanket in all cases.     

Novel methodologies and a comparative study for manufacturing systems performance evaluations

The purpose of this work is to establish complex fuzzy methodologies in the evaluation of a manufacturing system’s performance. Many empirical studies have been presented about the evaluation of manufacturing system’s performance. However, the performance evaluation is quite subjective, since it relies on the individual judgment of the managers who have different, various and multi-factor assessment methods of a system’s performance. In this study, two fuzzy modeling designs were developed and in the construction of the models, a hierarchy process was used. In the first method, the performance factors and the Analytic Hierarchy Process (AHP) were fuzzified and the use of fuzzy numbers and a fuzzy AHP for this problem was recommended. Also, the relative importance of these factors with respect to each other and their contribution to the overall performance was quantified with fuzzy linguistic terms. In the other method, we proposed Approximate Reasoning (AR) based on experts’ knowledge which is represented with the collection of the rules. These fuzzy rule bases are “if-then” linguistic rules that are formed with linguistic variables such as poor, below average, average, above average and superior. Additionally, the problem was structured with the normal AHP and System-With-Feedback (SWF), Finally, these methods were compared. The results showed that fuzzy AHP leads to the best result. It is expected that the recommended models would have an advantage in the competitive manufacturing including cost, flexibility, quality, speed and dependability.     

The impact of stochastic resource availability on cognitive network performance: modeling and analysis

Cognitive radio networks emerge as a promising solution for overcoming shortage and inefficient use of bandwidth resources by allowing secondary users (SUs) to access the primary users' (PUs) channel so long as they do not interfere with them. The dynamical spectrum availability makes SU's packet average delay one of the most important performance measures of a cognitive network. It is important to understand the nature of delay, as well as its dependence on PU behaviors. In this paper, we analytically model and analyze the dynamics of the spectrum availability and their impact on the SU's packet delay. The cognitive network is modeled as a discrete‐time queueing system. PU channel occupancy is modeled as a two‐state Markov chain. Our contribution in this paper is defining and characterizing the properties of the random process that describes the availability of the opportunistic resources. In addition, we apply the mean residual service time concept to achieve an analytical solution for the queueing delay. Moreover, inspired by the slotted Aloha system, we model the packet service mechanism and determine the manner in which it depends on the resource availability. The delay becomes unbounded if the spectrum availability dynamics are not carefully considered in network design. Copyright © 2015 John Wiley & Sons, Ltd.     

Role of public space design on the perception of historical environment: A pilot study in Amasya

The experience, perception, awareness, and appreciation of the environment created by public spaces are important elements of urban design. In this context, a strong link exists between perception, public spaces, and historical cities. Amasya is one of the multilayered historical cities in Anatolia. Amasya’s holistic urban texture, close relationship with the river, and public spaces are associated with both the Iris River and the historical texture. This pilot study examines the Yalıboyu Promenade, a contemporary open public space designed along the river and across the historical texture in Amasya in Turkey to reveal how it affects people’s perception of the historical environment. The study uses the mixed method approach, which includes qualitative and quantitative data. Following the theoretical discussion, the study investigates the context of the promenade. The survey results revealed how the first-time visitors had perceived the historical texture of the promenade based on Rapoport’s method of using environmental signs. The results were interpreted by jointly evaluating qualitative and survey data. Furthermore, although some aspects need improvement, the promenade solidifies the perception of the historical environment. Overall, when the public space is integrated with the historical environment and public life, it offers multidimensional contributions that cannot be ignored. Therefore, examining the promenade from perceptual aspects and offering a design approach to promote integration with the historical environment may help to establish a precedent case for future initiatives.     

Cause of Damage and Failures in Silo Structures

Silos are special structures subjected to many different unconventional loading conditions, which result in unusual failure modes. Failure of a silo can be devastating as it can result in loss of the container, contamination of the material it contains, loss of material, cleanup, replacement costs, environmental damage, and possible injury or loss of life. Silo damage and failures that occurred in different regions of the world are presented in the paper using illustrative photos. Also provided are a review and discussion of the common or spectacular silo failures due to explosion and bursting, asymmetrical loads created during filling or discharging, large and nonuniform soil pressure, corrosion of metal silos, deterioration of concrete silos due to silage acids, internal structural collapse, and thermal ratcheting. Silo damage and failures from several earthquakes are also presented.