202 research outputs found
The Human Blockage Impact on ARIS Assisted D2D Communication Systems
Aerial reconfigurable intelligent surface (ARIS), is an intelligent
reflecting surface (IRS) mounted by unmanned aerial vehicle (UAV), represent a
promising candidate for assisting device to device (D2D) millimeter wave
(mmWave) communication in temporal and urgent situations, e.g., open-air
events. IRS can efficiently mitigate the high blockage impact on mmWave
propagation signal in base station to device use case. But, the scenario of D2D
communication is different as both the transmitter (TX) to ARIS and the ARIS to
receiver (RX) links are highly susceptible to be blocked due to the low height
of the TX and RX. Consequently, in this paper, the impact of human bodies
blockage on ARIS aided D2D mmWave communication is studied. Firstly, we assure
the effectiveness of using ARIS in this network to significantly enhance its
performance, then, the effect of ARIS height on the blockage occurrence and
system performance is investigated to find out the optimum height. Our results
proves that ARIS highly mitigates the blockage, reduces it by 85%, comparable
to the case without it. Moreover, a high increase in system spectral
efficiency, 1.2 bps/Hz, can be guaranteed, if ARIS is configured at optimum
height
RXs Directions based Codebook Solution for Passive RIS Beamforming
Recently, reconfigurable intelligent surface (RIS) has immensely been
deployed to overcome blockage issue and widen coverage for enabling superior
performance 6G networks. Mainly, systems use RIS as an assistant to redirect
the transmitter (TX) incident signal towards the receiver (RX) by configuring
RIS elements amplitudes and phase shifts in a passive beamforming (PBF)
process. Channel estimation (CE) based PBF schemes achieve optimal performance,
but they need high overhead and time consumption, especially with high number
of RIS elements. Codebook (CB) based PBF solutions can be alternatives to
overcome these issues by only searching through a limited reflection patterns
(RPs) and determining the optimal one based on a predefined metric. However,
they consume high power and time relevant to the used CB size. In this work, we
propose a direction based PBF (D-PBF) scheme, where we aim to map between the
RXs directions and the codebook RPs and store this information in an updated
database (DB). Hence, if the matching between a coming RX and a particular RP
exists, the proposed scheme will directly select this RP to configure the RIS
elements, otherwise, it memorizes this codeword for future searching. Finally,
if the matching failed, searching through the memorized RPs will be done to
find the optimal one, then updating the DB accordingly. After a time period,
which depends on the CB size, the DB will converge, and the D-PBF scheme will
need no searching to select the optimal RP. Hence, the proposed scheme needs
extremely lower overhead, power, and time comparable to the CE and conventional
CB based solutions, while obtaining acceptable performance in terms of
effective rate
A robust structure identification method for evolving fuzzy system
This paper proposes a robust structure identification method (RSIM) based on incremental partitioning learning. RSIM starts with an open region (initial domain) that covers all input samples. The initial region starts with one fuzzy rule without fuzzy terms and then evolves through incremental partitioning learning, which creates many subregions for system error minimization. The three major contributions of the proposed RSIM are as follows: It locates sufficient splitting points provided through a robust partitioning technique, determines the optimum trade-off between accuracy and complexity through a novel partition-selection technique, minimizes global error through global least square optimization. These contributions offer many remarkable advantages. First, RSIM provides a solution for the curse of dimensionality. Second, RSIM can also be applied to low-dimensional problems. Third, RSIM seeks to produce few rules with low number of conditions to improve system readability. Fourth, RSIM minimizes the number of fired rules. Therefore, RSIM can achieve low-level complexity systems. Three low-dimension and six high-dimension and real-life benchmarks are used to evaluate the performance of RSIM with state-of-the art methods. Although RSIM has high interpretability, the results prove that RSIM exhibits greater accuracy than other existing methods
Competing risks for reliability analysis using Cox’s model
Purpose – Cox’s model with Weibull distribution and Cox’s with exponential distribution are the most important models in reliability analysis. This paper seeks to show that, with a large sample size based on expectation maximization (EM) algorithm, both models give similar results.
Design/methodology/approach – The parameters of the models have been estimated by method of maximum likelihood based on EM algorithm. The objective of this analysis is to fit the modification of Cox’s model with Weibull distribution and Cox’s with exponential distribution, examine its
performance and compare their results with Crowder et al.
Findings – A simulation study indicates that the parametric Cox’s model with Weibull distribution gives similar results to Cox’s with exponential distribution, especially for a large sample size. Also, the modification of the two models showed better results compared with Crowder et al., especially for the second causes of failure.
Originality/value – A modification of the two competing risk models has mostly been applied in failure time data and simulation data. The results of the simulation study indicate that the Weibull and exponential are suitable for Cox’s model as they are easy to use and it can achieve even higher accuracy compared with other distribution models
Biometrics for internet‐of‐things security: A review
The large number of Internet‐of‐Things (IoT) devices that need interaction between smart devices and consumers makes security critical to an IoT environment. Biometrics offers an interesting window of opportunity to improve the usability and security of IoT and can play a significant role in securing a wide range of emerging IoT devices to address security challenges. The purpose of this review is to provide a comprehensive survey on the current biometrics research in IoT security, especially focusing on two important aspects, authentication and encryption. Regarding authentication, contemporary biometric‐based authentication systems for IoT are discussed and classified based on different biometric traits and the number of biometric traits employed in the system. As for encryption, biometric‐cryptographic systems, which integrate biometrics with cryptography and take advantage of both to provide enhanced security for IoT, are thoroughly reviewed and discussed. Moreover, challenges arising from applying biometrics to IoT and potential solutions are identified and analyzed. With an insight into the state‐of‐the‐art research in biometrics for IoT security, this review paper helps advance the study in the field and assists researchers in gaining a good understanding of forward‐looking issues and future research directions
Indoor path loss model for 4G wireless network at 2.6 GHz
In this paper, a short-range, narrowband indoor propagation at 2.6 GHz was measured and modeled. The measurement campaign was conducted to characterize the path loss (PL) of Radio frequency (RF) at the Razak School building corridor. The corridor has unique structure and segmented in different sections. The irregular structure of corridor, further with various interior material used gives the unique characterization to the received power. The research work made in this paper is predominately targets to characterizing radio link of 2.6 GHz frequency in typical indoor corridor
Internet use and addiction among medical students of Universiti Sultan Zainal Abidin,Malaysia
The use of Internet has now become indispensable, and the technology has revolutionized the medical education and practice worldwide. Currently, medical students and
professionals have an enormous opportunity to keep them always updated with the exponential growth of knowledge because of potential progression of Internet throughout the world that enables them to become a lifelong learner. Internet addiction is a widespread phenomenon among students and academicians at universities in Malaysia. Students use the Internet for recreational purpose and personal and professional development. The Internet has become an integral part of day-to-day life of the university students, including medical students. The aim
of the present study was to examine the Internet use and addiction among students of Universiti Sultan Zainal Abidin, Malaysia. Methods: This was a cross-sectional study in which a questionnaire, Internet Addiction Diagnostic Questionnaire, developed by the Center for Internet Addiction, USA, was used. One hundred
forty-nine medical students of Universiti Sultan Zainal Abidin participated in this study. Data were analyzed using Statistical Package for the Social Sciences software. Results: The mean scores were 44.9±14.05 and 41.4±13.05 for male and female participants, espectively, which indicated that both the genders were suffering from mild Internet addiction. Conclusion: This study shows almost similar level of Internet usage among medical students irrespective of their socioeconomic background, with no statistically significant (p>0.05) differences,
except among the years of study (p=0.007). Overall, from the research data and having worked with this cohort very closely, Universiti Sultan Zainal Abidin medical students can be labeled as wonted and recurring users of the Internet. Nevertheless, it is very difficult to define as Internet addicts or pathological users of the Internet because of small sample size and cross-sectional study
Natural product activity against Methicillin-Resistant Staphylococcus aureus genes
Methicilin Resistant Staphylococcus aureus (MRSA) implicated in many post-surgical and cancer treatment as well hospital and community fatalities need to be treated with an effective alternative antimicrobial agent. In the search for anti-MRSA agent, 2 types of natural products were investigated for inhibitory activity against MRSA. In addition to the bioassay, the activity of the anti-MRSA agent was elucidated based on the effect of both natural products on nucleotide changes of chromosome-encoded genes. In this study, the methanol extract of the red marine algae and the natural pure honey were studied for its antibacterial property based on disc diffusion test and Minimum Inhibitory Concentration (MIC). The effects of both natural products on selected gene sequences of S. aureus’s were determined by RT-PCR analysis. The genes of interest, which have been chosen in this study, are genes that are involved in the antibacterial mechanism including inhibition of cell wall synthesis, protein synthesis and nucleic acid synthesis. Five genes of interest chosen in this study include mecA gene, mecR1 gene, mecI gene, adaB gene and sav1017 gene. The results for antibacterial property showed the methanol extract of a red seaweed and the pure honey, inhibited growth of S. aureus strain according to the inhibition zones around discs saturated with the seaweed extract and pure honey, respectively. The MIC test showed decrease in growth of MRSA isolates after growing in broth incorporated with the extract and honey, respectively. The effect of the inhibitory activity of the natural products on selected gene sequences showed that several nucleotide changes occurred in the sequences of certain genes of interest based on the gene sequences of the cDNA after RT-PCR was carried out on the mRNA of S. aureus treated with the natural products. This research underlined that the inhibition effect of the natural products may be chromosome mediated evidenced by the changes of chromosome-encoded genes. The significant findings on activities of the seaweed extract and pure honey may become very useful in the process to find a better treatment for S. aureus infection especially, for the multiple drug resistant isolates. In addition, it is also, a new finding for natural product discovery through gene-expression analysis
The mediating role of absorptive capacity in its effect on organizational support factors and technological innovation
The purpose of this research is to examine the relations between organizational support factors
and absorptive capacity and their combined effects on technological innovation.Through a comprehensive literature review constructs were developed.Multiple regression analysis used to test research hypotheses based on a sample of 52 engineers within the Directorate of Electricity in Sulaimani city in Kurdistan region north of Iraq. Based on empirical research, the results showed that organizational support factors had a significant effect on technological innovation and absorptive capacity.It was also indicated that absorptive capacity plays a full mediation rule between organizational support factors and technological innovation.This appears to be the first research to test the relationships between organizational support factors and absorptive capacity and their consequences in the particular context of technological innovation including
product innovation and process innovation
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