Carbon nanotubes composite materials for dipole antennas at terahertz range

This paper aims to present two types of carbon nanotubes composite materials (CNTs-composite) for antenna applications within terahertz (THz) frequency band. These composite materials consist of CNTs coated by copper and silver, separately, to construct CNTs-copper and CNTs-silver composite materials, respectively. The comparisons between the dipole antennas of these structure materials with CNTs dipole antenna and copper dipole antenna are presented to exhibit performance evaluation of the presented new dipole antennas. The mathematical modeling of CNTs-composite material is presented in this paper. The results obtained from the comparisons CNTs-copper and CNTs-silver dipole antennas are presented based on S 11 parameters, gain and efficiency

Electromagnetic modelling of bundle of single-walled carbon nanotubes with circular geometry for antenna applications

This paper aims to present an effective electromagnetic (EM) modelling approach for circular bundle of single-walled carbon nanotubes (CBSWCNTs), based on the electrical conductivity, relative complex permittivity and linear distribution impedance by applying General Ohms law for this bundle. The equivalent single conductor material (ESCM) model for personification the CB-SWCNTs is presented in this paper. The main target of this modelling approach is to estimate and investigate the EM properties of CBSWCNTs using common EM engineering tool solver CST (MWS). For this purpose, the CB-SWCNTs and ESCM dipole antennas will be designed and implemented using CST (MWS). Mathematically, the equivalent conductivity model, relative complex permittivity and other parameters of the CB-SWCNTs will be derived in this paper and considered as equivalent material parameters for the ESCM. This modelling technique is expected to provide new avenues for designing different antenna structures

An Enhanced Gain of Yagi-Uda Antenna with Folded Dipole for Amateur Radio VHF Band Application

This paper presents an enhanced gain of Yagi-Uda antenna with folded dipole for amateur radio Very High Frequency (VHF) band. The analysis is performed using CST Microwave Studio Suite software. The structure of this directional antenna integrates three main parts which are directors, reflectors and feeder point of 50 Ω. The performance of the proposed antenna has a tolerable reflection coefficient below -10 dB at 144.46 MHz. A maximum gain of around 14.03 dB with a good efficiency of 75.6% is achieved. The gain of the antenna increases up to 2% when added with 7 elements of reflector than with one element of reflector and enhanced significantly by 23.6% compared to the conventional Yagi-Uda antenna

Critical data-based incremental cooperative communication for wireless body area network

Wireless Body Area Networks (WBANs) are single-hop network systems, where sensors gather the body’s vital signs and send them directly to master nodes (MNs). The sensors are distributed in or on the body. Therefore, body posture, clothing, muscle movement, body temperature, and climatic conditions generally influence the quality of the wireless link between sensors and the destination. Hence, in some cases, single hop transmission (‘direct transmission’) is not sufficient to deliver the signals to the destination. Therefore, we propose an emergency-based cooperative communication protocol for WBAN, named Critical Data-based Incremental Cooperative Communication (CD-ICC), based on the IEEE 802.15.6 CSMA standard but assuming a lognormal shadowing channel model. In this paper, a complete study of a system model is inspected in the terms of the channel path loss, the successful transmission probability, and the outage probability. Then a mathematical model is derived for the proposed protocol, end-to-end delay, duty cycle, and average power consumption. A new back-off time is proposed within CD-ICC, which ensures the best relays cooperate in a distributed manner. The design objective of the CD-ICC is to reduce the end-to-end delay, the duty cycle, and the average power transmission. The simulation and numerical results presented here show that, under general conditions, CD-ICC can enhance network performance compared to direct transmission mode (DTM) IEEE 802.15.6 CSMA and benchmarking. To this end, we have shown that the power saving when using CD-ICC is 37.5% with respect to DTM IEEE 802.15.6 CSMA and 10% with respect to MI-ICC

Sri Cempaka Ayu Enterprise / Ilda Izanie Ahmad... [et al.]

Sri Chempaka Ayu Enterprise is a company that offer health and beauty care to their customer. they provide traditional treatment such as ‘jamu’, traditional massage and herbs steam bath. The company is located at Alor Setar, Kedah

Performance analysis and discrimination procedure of two-group location model with some continuous and high-dimensional of binary variables

This research’s primary goal was to evaluate the performance analysis of the recently constructed smoothed location models (SLMs) for discrimination purposes by combining two kinds of multiple correspondence analysis (MCA) to handle high dimensionality problems arising from the binary variables. A previous study of SLM, together with MCA as well as principal component analysis (PCA), displayed that the misclassification rate was still very high with respect to a large number of binary variables. Thus, two new SLMs are constructed in this paper to solve this particular problem. The first model results from the combination of SLM with Burt MCA (denoted as SLM+Burt), and the second one is with the joint correspondence analysis (denoted as SLM+JCA). The findings showed that both models performed well for all sample sizes (n) and all binary variables (b) under investigation, except n=60 and b=25 for the SLM+JCA model. Overall, the SLM+JCA model yields a greater performance in contrast to the SLM+Burt model. Moreover, the concept and procedures of the discrimination for the two-group classification conducted in this paper can be extended to multi-class classification as practitioners often deal with many groups and complexities of variables

Micronuclei Formation and 8-Hydroxy-2-Deoxyguanosine Enzyme Detection in Ovarian Tissues After Radiofrequency Exposure at 1800 MHz in Adult Sprague–Dawley Rats

Human fertility and its correlation to ovarian function and cytological changes are linked to ever-increasing use of mobile phones. Wireless communications have become a critical topic of concern because of an increasing number of studies in this field with controversial outcomes. The aim of this study was to assess the genotoxic effect of GSM frequency at 1800 MHz on ovarian function. Sixty female Sprague–Dawley rats were distributed over six groups (control group and the exposure groups with whole-body exposure for 2 h/day, 7 days/week for 15, 30 and 60 continuous days). The study investigated the oxidative stress, 8-hydroxy-2-deoxyguanosine enzyme, micronuclei formation and histopathological changes in ovarian tissue. The results showed an induced oxidative stress via an increase in lipid peroxidation and decreased antioxidant enzyme activity. There was also an elevation in the 8-hydroxy-2-deoxyguanosine enzyme and an increased rate of micronuclei formation in ovarian tissues of exposed animals with 60-day exposure compared with control animals. Cytological changes were recorded such as micronuclei formation, vacuolation, degeneration and impaired folliculogenesis. The study suggests that GSM frequency at 1800 MHz was negatively impacted on female reproductive performances mediated by oxidative stress induction and 8-hydroxy-2-deoxyguanosine formation leading to overall impaired ovarian function

Assessment of worn textile antennas’ exposure on the physiological parameters and well-being of adults

This paper presents the assessment of short-term wireless body area network (WBAN) exposure, which is operated at the industrial, scientific, and medical (ISM) band (2.45 GHz) in the vicinity of the human body. The experiment utilizes two popular textile antenna topologies, a planar monopole and a patch antenna as the radiating sources. The objective of this experiment is to investigate whether the exposure from WBAN may influence the physiological parameters (body temperature, blood pressure, and heart rate) and the well-being of the wearer. Counter-balanced, crossover, and the single-blind method was applied in the experimental setup. P-value is the probability value, under the assumption of no effect or no difference (the null hypothesis) of obtaining a result equal to or more extreme than what was actually observed. If P<; 0.05, it indicates that P-value will be less than the level of significance. Thus, the null hypothesis (no effect or no difference) can be rejected, and it can be concluded that there exist effects to the respondents. The results showed that there is statistically no significant difference between the active exposure and the Sham (no exposure) which may affect the physiological parameters and well-being of the wearers, with P>0.05, which failed to reject the null hypothesis (no effect)

Enhancement of the duty cycle cooperative medium access control for wireless body area networks

This paper presents a novel energy-efficient and reliable connection to enhance the transmission of data over a shared medium for wireless body area networks (WBAN). We propose a novel protocol of two master nodes-based cooperative protocol. In the proposed protocol, two master nodes were considered, that is, the belt master node and the outer body master node. The master nodes work cooperatively to avoid the retransmission process by sensors due to fading and collision, reducing the bit error rate (BER), which results in a reduction of the duty cycle and average transmission power. In addition, we have also presented a mathematical model of the duty cycle with the proposed protocol for the WBAN. The results show that the proposed cooperative protocol reduced the BER by a factor of 4. The average transmission power is reduced by a factor of 0.21 and this shows the potential of the proposed technique to be used in future wearable wireless sensors and systems

On Body Characterization for On-Body Radio Propagation Channel using Wearable Textile Monopole Antenna

This paper presents the experimental investigation of the characterization of the narrowband on-body radio propagation channel at 2.45 GHz. Wearable planar textile monopole antennas (TM) were used in this measurement campaign. The measurements were conducted in the RFshielded room environment, considering eight on-body radio links. A statistical analysis was conducted on the spectral parameters of the channel to enable the prediction and modeling of dynamic on-body radio propagation characteristics. The empirical data were fitted to several wellknown statistical models to determine the model that provided the best fit for the data. The results showed that the path loss exponent was consistent with the results of previous studies. The results also demonstrated that lognormal distribution was found to be the best fit for path loss in dynamic on-body radio propagation channel