Turbo Coded Signals Over Wireless Local Loop Environment

In this paper, the performance of turbo coded signals are investigated over Wireless Local Loop (WLL) environment with no side information on the phase noise and and no channel state information (CSI). We assume that the transmitter and the receiver are point-to-point microwave links, separated by WLL which is modelled as 1+Dⁿ/Partial Response Microwave Channel (PMRC) with realizable and practical medium parameters. Here, the combined effects of the nonideal coherent receiver on the phase of the received amplitude and of a noisy carrier reference are considered, each modelled by the Rayleigh and Tikhonov distributions respectively. As an example, the jitter performance of turbo coded signals are evaluated over 1+Dⁿ/PRMC with effective signal-to-noise ratio in the carrier tracking loop, fading parameter, iteration number and frame data block size. The numerical results clearly demonstrate the error performance degradation due to both amplitude fading and phase noise process.     

The prevalence of Escherichia coli O157 and O157:H7 in ground beef and raw meatball by immunomagnetic separation and the detection of virulence genes using multiplex PCR

The present study was conducted to investigate the presence of Escherichia coli O157 and O157:H7 strains and to detect the presence of the stx1, stx2, and eaeA genes in isolates derived from 200 samples (100 samples from fresh ground beef and 100 samples from raw meatball). The samples were purchased from the Samsun Province in Turkey, over a period of 1 year. Enrichment-based immunomagnetic separation and multiplex polymerase chain reaction were applied for these analyses. E. coli O157 was detected in five of the 200 (2.5%) samples tested (one isolated from ground beef and four from meatball samples), whereas E. coli O157: H7 was not detected in any sample. During the analysis, eight strains of E. coli O157 were obtained. The genes stx1, stx2, and eaeA were detected in two E. coli O157 isolates obtained from two meatball samples, whereas only the eaeA and the stx2 genes were detected in four E. coli O157 strains that were isolated from one meatball sample. None of the stx1, stx2, and eaeA was detected in the E. coli O157 isolates obtained from the ground beef and the one meatball samples.     

A novel wind speed modeling approach using atmospheric pressure observations and hidden Markov models

Modeling the wind speed data has important implications in wind studies, providing valuable insight and parametric quantities for further engineering analysis. The classical modeling approach is to fit the probability distribution to a known model and estimate statistical parameters like mean and variance. Such models lack the time variation properties and ignore cross-dependencies between other meteorological data. In this paper a procedure is developed to model the wind speed data using a dependent process of atmospheric pressure in the form of hidden Markov models (HMMs). Consequently, the inherent dependencies between the wind speed and pressure are exploited. HMMs relate the two quantities in a framework which eliminates the necessity of direct sample-wise correlations, and avoid direct time-series analysis complications of the stochastic wind speed data at a marginal expense of easy pressure measurements. The experimental data were obtained from recordings of hourly atmospheric pressure and wind speed values for two cities in Turkey, namely Izmir and Kayseri. Model details and numerical results are presented.     

Synthesis of Cherry Stalk Extract Based Organic@Inorganic Hybrid Nanoflowers as a Novel Fenton Reagent: Evaluation of Their Antioxidant,Catalytic, and Antimicrobial Activities

First time in this study, organic@inorganic hybrid copper nanoflowers (Cu NFs) were synthesized by using cherry stem extract as an organic component and Cu²⁺ ion as an inorganic component. For this purpose, cherry stalk extracts were obtained by using ethanol and water solvents. Cu NFs were synthesized in different amounts of extract (100–1000 µl) and under various pH (7.4–9) conditions. The morphologies of the synthesized Cu NFs were evaluated by field emission scanning electron microscope (FE-SEM). The functional groups in the cherry stem extract, which play an active role for the synthesis process, and the crystal structure of NFs were investigated by Fourier transform ?nfrared spectroscopy and X-ray diffraction techniques, respectively. It has been determined by the FE-SEM analysis that ethanol and water based cherry stem extracts are suitable for Cu NFs synthesis in a wide range of pH (7.4–9). This data is crucial for overcoming important limitations for NF synthesis, such as narrow-range medium pH. The catalytic, antioxidant, and antimicrobial activities of Cu NFs were evaluated. It was revealed that Cu NFs have catalytic, antioxidant, and antimicrobial activities. It is recommended that, cherry stem extract and different inorganic components are functional to synthesize numerous NFs and to evaluate the adequacy of use in biomedical fields.

     

A SWOT-AHP analysis on biodiesel as an alternative future marine fuel

Clean Technologies and Environmental Policy - Alternative fuels especially those produced in a green way are essential for meeting supplying the world's growing energy needs. Biodiesel is...     

Hertzian crack propagation in graded glass/ceramic composites

In literature, the concept of material gradation is shown to inhibit surface crack initiation in glass/ceramic composites subjected to Hertzian indentation. However, surface cracks could yet initiate due to relatively higher loadings or in the presence of surface flaws/defects. Hence, characterization of graded composites concerning the resistance against Hertzian crack initiation and propagation manifests itself as a prominent matter. In this study, axisymmetric Hertzian cracks evolving in graded glass/ceramic composites propelled by a rigid cylindrical punch are investigated employing a novel recursive method, called the stacked-node propagation procedure. Crack trajectories and their propagation susceptibilities are predicted via the minimum strain energy density (MSED) criterion regarding the crack growth resistance (R-curve) of ceramics. The stress trajectory approach is also considered for a homogeneous glass to reveal the reliance and effectiveness of the MSED criterion in the present crack problems. The Mori–Tanaka relations are adopted to model the elastic modulus and Poisson's ratio variations through the composites, which are implemented on the simulations via the homogeneous finite element approach. Hertzian crack problem of a practically producible graded composite comprised of oxynitride glass and a fine-grained silicon nitride ceramics (Si₃N₄) is treated as a case study. The degree of material gradation is assessed for the mitigation of surface crack initiation and propagation risks.     

Polyols and chocolate technology: recent developments and advances

Reducing the sugar level in chocolate and developing low-calorie products are important for meeting consumer expectations, supporting public health and adapting to current consumption trends. However, the identification of bulking agents to be used for this aim is a critical factor. The most commonly used sugar alternatives for this aim are polyols. In this study, recent advances and developments for using possibilities of polyols in chocolate technology were discussed and future perspectives were highlighted. Partially and/or complete replacing of sugar with polyols can provide a low-calorie product. In addition, the use of mixtures consisting of more than one polyol is an approach that can be used in chocolate sugar substitution. Optimization of refining, conching and tempering processes by considering polyol type and content may contribute to the development of chocolate with improved quality properties and shelf life. However, polyol and bioactive compounds interactions and possible effects on bioaccesibility, bioavalibility and stability of these compounds in chocolate composition and pre- and post-digestion periods should be deeply investigated. In addition, the conching methods and conditions used is another factor to be considered in the use of polyols.     

The Use of Digital Image Processing Method to Estimate the Foam Characteristics of Polyurethane

Four air-bubbled polyurethane (PU) foams with different polyol:PMDI wt.% are produced, respectively. The chemical reaction mechanisms of polyurethane and bubble formation are proposed by performing standard Gibbs free energy calculations using the DFT M06-2X/6-31+G(d,p) method. The local minima, transition states, and intermediates in reaction mechanisms are detected. It is concluded that both reactions are exothermic. Then, raw images of the produced PU foams are taken with a 13 MP mobile phone camera, which can be considered inexpensive, and the mean radii of the pores are calculated by an image processing based method (IPBM) on a standard desktop computer with an i5 processor. It is determined that there is a close relationship between the calculated mean radius and instrumentally measured thermal conductivity coefficient of the foams. However, the thermal conductivity coefficients are independent of the calculated number and percentage of the pores. The mean radii of the samples calculated by the proposed IPBM are close to that of the SEM, with acceptable relative errors of less than 10%. Finally, it is concluded that IPBM, which is a more cost-effective, cleaner, and faster method than SEM, might replace SEM in the air bubble analysis of PU foams.     

Stability analysis and controller design for consensus in discrete-time networks with heterogeneous agent dynamics

In this paper, we study the heterogeneous consensus problem in directed networks consisting of first- and second-order agents that can only receive the position states of their neighbors. Necessary and sufficient conditions on the controller parameters are obtained in order to achieve consensus in the network. The mathematical expressions of the consensus equilibria are given for two different scenarios. Furthermore, we propose a systematic method for choosing controller parameters to ensure stability in a network of agents with heterogeneous dynamics. Several numerical examples are also provided to illustrate the theoretical results.