All-aerosol-jet-printed highly sensitive and selective polyaniline-based ammonia sensors: a route toward low-cost,low-power gas detection

Journal of Materials Science - We report the design and scalable fabrication of a low-cost and low-power polyaniline-based (PANI) ammonia (NH3) gas sensor on polyimide (PI) substrates using...     

Path to success: an analysis of US educated elite academics in the United States

Few academics go on to become professors at prestigious universities. Candidates must have a very strong educational background in addition to demonstrating a high level of effort and academic ability. We analyze the educational backgrounds of elite academics with two main objectives. First, we evaluate the educational institutions in terms of the number of graduates who have become professors at prestigious universities. Second, we analyze the professor’s path to success to shed light on issues such as mobility and inbreeding. We analyze the educational backgrounds of 14,310 full professors from 48 top universities in the United States. We confine our analysis to undergraduate and graduate degrees attained within the United States. Some of our main findings are as follows: (a) 72% (44%) of the professors obtained their Ph.D. (undergraduate) degrees from 20 universities. (b) The top 17 universities with the highest number of Ph.D. alumni who became professors at prestigious universities were also among the top 20 universities with the highest number of undergraduate alumni who became professors at prestigious universities. (c) 70% of the professors who work at private universities obtained their degrees from private universities, whereas only half of the professors who work at public universities obtained their degrees from public universities. (d) Only 16% of the professors live in the same state in which they obtained their undergraduate degrees, which indicates a much higher mobility than the average graduate degree holder. (e) Only 4% of the professors work at the universities from which they graduated. (f) Professors graduate significantly faster than the median Ph.D. graduate.     

Determination of theoretical stress concentration factor for circular/elliptical holes with reinforcement using analytical,finite element method and artificial neural network techniques

Neural Computing and Applications - Machine parts always work under different types of stresses or loading conditions. The sudden dimensional changes lead to sudden increase in stress on the...     

Automated selection of optimal material for pressurized multi-layer composite tubes based on an evolutionary approach

Decision making on the configuration of material layers as well as thickness of each layer in composite assemblies has long been recognized as an optimization problem. Today, on the one hand, abundance of industrial alloys with different material properties and costs facilitates fabrication of more economical or light weight assemblies. On the other hand, in the design stage, availability of different alternative materials apparently increases the complexity of the design optimization problem and arises the need for efficient optimization techniques. In the present study, the well-known big bang–big crunch optimization algorithm is reformulated for optimum design of internally pressurized tightly fitted multi-layer composite tubes with axially constrained ends. An automated material selection and thickness optimization approach is employed for both weight and cost minimization of one-, two-, and three-layer tubes, and the obtained results are compared. The numerical results indicate the efficiency of the proposed approach in practical optimum design of multi-layer composite tubes under internal pressure and quantify the optimality of different composite assemblies compared to one-layer tubes.

     

Prediction of Channel Utilization with Artificial Neural Networks Model in Mac Layer in Wireless Local Area Networks

Wireless Personal Communications - The use of channels in WLANs affects data communication. RTS Fragmentation Threshold (RTSFT), Fragmentation Threshold (FT), and Buffer Size (BS) input values;...     

On the dual nature of intra-urban borders: The case of a Romani neighborhood in Istanbul

This essay questions the nature of intra-urban borders from a politico-ethical point of view. Namely: to what extent are intra-urban borders acceptable at a time of proliferating discourses about a borderless world, and open cities? We discuss this through a case study of Sulukule – a historic neighborhood home to a millennium old Roma community located within the historic city center of Istanbul – in the context of the urban renewal project launched by the local municipality. The often cited “humanitarian” pretext for the renewal project is “incorporating” the Sulukule’s poor Roma community into the city and tearing down the borders demarcating their ghetto. Eventually, this discourse of incorporation served to instigate a rapid episode of gentrification in the area. Offering a critical perspective on the municipality’s renewal project, and through a discussion of the often conflicting premises of the discourses of the “right to the city” and the “group right to difference,” this essay argues that intra-urban borders are “undecided” separators and calls for policy tools that are responsive to the enabling aspects of bordering processes.     

Transporting of spruce timbers by URUS MIII cable system from selective forests of Artvin region

The aim of the research was to determine the productivity of the URUS MIII cable system during transporting of Spruce timbers from the Turkey mountainous selective forests of Spruce, Scotch pine and Beech. This research was conducted in Artvin General Directorate of Forestry. Cable system productivity was determined by the time study method. The research shows the results of some working characteristics of the URUS MIII cable system, such as; transporting speed of carriage (loaded and unloaded), load volume, time consumptions of felling area, fuel consumptions, productivity of cable system and transporting distance.     

Simulation of a VAV air conditioning system in an existing building for the cooling mode

In this study, simulation of a variable air volume (VAV) air conditioning system in an existing office building is presented for the cooling mode. A building simulation package was used for the simulation [DOE, EnergyPlus Engineering Document, Version 1.3., U.S. Department of Energy, Washington, DC, 2005]. The design information of the existing office building, the actual number of the internal load sources such as occupants, lighting, office equipments and the manufacturer's data for the existing rooftop unit (RTU) and the VAV boxes were used in the building simulation package. The simulation results; RTU power consumption, indoor zone temperature and relative humidity, were validated with the data obtained from the on-site measurements performed in the existing office building under the same outdoor conditions. It was found that 71.1% of all simulated power consumption data falls within ±15% range from the experimental data. The reason for the existence of some data out of band is due to the possible errors associated with the difference in the solar data used for the location 40 km away from the experimental location. It was found that 90.6-94.7% of the indoor temperature experimental data fall within ±1.5 °C range from the simulated data, and 88.3-91.3% of the indoor relative humidity data fall within ±18% range from the simulated data.     

Utilization of borogypsum as set retarder in Portland cement production

Boron ores are used in the production of various boron compounds such as boric acid, borax and boron oxide. Boric acid is produced by reacting colemanite(2CaO·3B₂O₃·5H₂O) with sulphuric acid and a large quantity of borogypsum is formed during this production. This waste causes various environmental problems when discharged directly to the environment. Portland cement is the most important material in the building industry. This material is produced by adding about 3-5% gypsum (CaSO₄·2H₂O) to clinker as a set retarder. The aim of this study was to stabilize borogypsum, and to produce cements by adding borogypsum instead of natural gypsum to clinker. Concrete using cement produced with borogypsum was tested to find the mechanical properties and the test values were compared with those of concrete from cement with natural gypsum. Compressive strength of concrete from cement produced with borogypsum was found to be higher than that of natural gypsum. Also, the setting time of cement with borogypsum was longer than that of the Portland cement.