Prediction of energy consumption for LoRa based wireless sensors network

Wireless Networks - This paper shows a method for predicting the lifetime of a wireless sensor network based on the LoRa Ra-01 wireless modules. To develop a prediction model of the energy...     

Experimental investigation of a solar energy heating system under the climatic conditions of Edirne

Seasonal storage of solar energy to supply the heat requirement of buildings in Edirne (41°39′54″N) has been examined experimentally. Solar energy has been stored in a cylindrical underground storage unit. Measurement values have been recorded per hour by means of a computerized recorder between July 2005 and May 2006. Monthly average temperature values of the heat storage unit and the surrounding ground have been calculated through the measurement results. The transient heat transfer which takes place between the heat storage unit and the surrounding ground has been calculated by means of the QuickField finite-element analysis program. It has been determined that the most significant deviations between the theoretical and the experimental temperature values turn out to be in question during the heating period. The annual solar fraction of the solar energy heating system has been determined as 53% for space heating and 85% for domestic water heating.     

Experimental and numerical investigation of heat and mass transfer during drying of Hayward kiwi fruits (Actinidia Deliciosa Planch)

In this paper we undertake an experimental and numerical study on heat and mass transfer analysis during drying of kiwi fruits. In the experimental part, the effects of various drying conditions in terms of air velocity, temperature and relative humidity on drying characteristics of kiwi fruits are investigated. In the numerical part, the external flow and temperature fields are studied using a commercial CFD package. From these fields, the local distributions of the surface convective heat transfer coefficients for the fruits are determined to predict the local convective mass transfer coefficients through the analogy between the thermal and concentration boundary layers (known as the Chilton–Colburn analogy). In addition, the time-dependent temperature and moisture distributions for different cases are obtained using the code developed to investigate heat and mass transfer aspects inside the fruits. Numerical results are then compared with experimental data and a considerably high agreement is obtained.     

Fuzzy approach for preliminary design of weak rock slopes in lignite mines

Rock slope failure modes are either driven by structurally controlled mechanisms (planar, wedge, or toppling failure) or lean upon the highly jointed or weak rock mass (circular failure). Developing practical tools for preliminary slope design is a popular topic among geotechnical society. This study proposes a practical methodology to predict a safe overall slope angle for weak rock slopes of lignite mines. Rock mass rating (RMR) and slope mass rating (SMR) classification systems can be remarkably misleading for weak rocks. Fuzzy modification was proven to improve rock and slope quality predictions. In addition, structurally controlled failures can be estimated more precisely. Later, a popular slope performance chart of Bieniawski that is based on RMR was modified by the fuzzy approach, and the computer models of a weak rock mass failure in a Turkish lignite mine are presented. The modified methodology was proven to be better suited to the weak rock conditions.     

The accumulation of La,Ce and Y by Lemna minor and Lemna gibba in the Keban gallery water,Elazig Turkey

This study investigated the phytoremediation ability of Lemna minor and Lemna gibba to accumulate lanthanum, cerium and yttrium from gallery water polluted by metals. L. minor and L. gibba were settled in the mining water and adapted to separate reactors. During the experiment, the water and plant samples were daily taken and the temperature, electric conductivity and pH of the water were daily measured in situ. These plants were firstly washed, dried in and then ashed at 300°C for 24 h in an oven. Both water and ashed plant samples were measured by ICP‐MS to detect the concentrations of lanthanum (La), cerium (Ce) and yttrium (Y). Although these elements are at low concentrations in gallery water, they were accumulated at the highest levels in L. gibba and in L. minor. This study showed that both plants have high ability to remove lanthanum, cerium and yttrium in gallery water polluted by different elements.     

Friction and wear behavior of styrene butadiene rubber‐based composites reinforced with microwave‐devulcanized ground tire rubber

In this work, the tribological properties of a new material obtained by revulcanization with styrene butadiene rubber (SBR) and devulcanized ground tire rubber (GTR) were investigated. GTR was devulcanized using the microwave method at a constant power while varying the microwave exposure time. Devulcanized rubber (DV‐R) and untreated GTR were revulcanized by mixing with SBR at different rates (10, 30, 50 phr). To determine friction and wear characteristics of the samples, pin (ball) on disc and abrasion tests were conducted. Scanning electron microscopy (SEM) was employed to observe the worn surfaces of the composites to correlate the experimental test results to the wear mechanisms. All of these tests and experiments were performed on original vulcanized rubber samples for comparison. The composites exhibited different friction and wear behavior due to morphology, dispersion behavior and devulcanization functionalization of ground tire rubber. In general, DV‐R/SBR composites exhibited improvement in both mechanical and tribological properties. However, the enhanced compatibility of DV‐R resulting from the specific chemical coupling of DV‐R with SBR was crucial for the mechanical, friction and wear properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42419.     

Fundamental periods of steel eccentrically braced frames

This paper describes formulation of a hand method that can be used to estimate the computed fundamental periods of vibration of building structures in general and steel eccentrically braced frames (EBFs) in particular. The developed method uses the Rayleigh's method as a basis and utilizes the roof drift ratio (RD_R) under seismic forces as a parameter. To obtain RD_R, more than 4000 EBFs were designed by considering the seismic hazard, number of stories, braced bay width and link length to bay width ratio as prime variables. A model was developed to estimate RD_R, which depends on the rigid plastic deformation mechanism for a typical EBF. The method was verified using design data produced as a part of this work as well as data published in literature. The verifications indicate that the proposed formulation is capable of providing acceptable estimates of the computed period. When compared with existing empirical period–height relationships, the proposed formulation offers closer estimates with reduced scatter. The method was further refined to derive new period–height relationships for two different seismicity regions. The accuracy of the relationship for high seismic regions was verified using measured periods of EBF buildings. Copyright © 2014 John Wiley & Sons, Ltd.     

Performance of joint multilevel/AES‐LDPCC‐CPFSK schemes over wireless sensor networks

In wireless sensor networks, data encryption and channel coding are considered together for ensuring secure and robust communication. In order to achieve this purpose, we introduce a new joint scheme, namely ‘Multilevel/Advanced Encryption Standard‐Low Density Parity Check Coded‐Continuous Phase Frequency Shift Keying (ML/AES‐LDPCC‐CPFSK)’. AES algorithm is the most powerful and widely used symmetric key cryptography in providing secure data transmission. LDPC codes have very large Euclidean distance and use iterative decoding algorithms. In this study, we have increased error performance employing multilevel structure to AES and LDPC. In all communications systems, phase discontinuities of modulated signals result in extra bandwidth requirements. CPFSK, which is a special type of continuous phase modulation, is a powerful solution for this problem. In this paper, we simulate error performance of ML/AES‐LDPCC‐CPFSK for regular LDPC codes. Simulation results are drawn for 4CPFSK, 8CPFSK and 16CPFSK over wireless cooperative sensor networks. Using this scheme, we are able to improve bit error performance, channel throughput, security level of communication and reduction in complexity compared with related schemes such as various turbo code structures. Copyright © 2009 John Wiley & Sons, Ltd.     

Antibacterial oil‐based polyurethane films for wound dressing applications

As an alternative to petroleum‐based polyol, hydroxyl containing material was prepared from linseed oil for polyurethane synthesis. Hexamethylene di‐isocyanate (HMDI) and/or 4, 4′‐methylene diphenyl di‐isocyanate (MDI) were used as isocyanate source. The polymerization reaction was carried out without catalyst. Polymer films were prepared by casting‐evaporation technique. The MDI/HMDI‐based polyurethane and its films had higher T_g and better thermal property than that of the HMDI‐based one because of the existence of benzene ring in the polymer chain. Static water contact angle was determined to be 74° and 77.5° for HMDI and MDI/HMDI‐based films, respectively. Water adsorption was found to be around 2.6–3.6% for both films. In vitro degradation of polyurethanes in phosphate buffered saline at 37°C was investigated by gravimetric method. Fourier transform infrared spectroscopy and scanning electron microscopy were used for confirmation of degradation on the polymer surface. The degradation rate of the HMDI‐based polyurethane film was found higher than that of the MDI/HMDI‐based film. Both the direct contact method and the MMT test were applied for determination of cytotoxicity of polymer films, and the polyurethane films investigated here was not cytotoxic. Silver‐containing films were prepared using Biocera A® as filler and were screened for their antibacterial performance against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and/or Bacillus subtilis. The films prepared with and without Biocera A® exhibited antibacterial activity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010