Secrecy performance of TAS/SC-based multi-hop harvest-to-transmit cognitive WSNs under joint constraint of interference and hardware imperfection

In this paper, we evaluate the secrecy performance of multi-hop cognitive wireless sensor networks (WSNs). In the secondary network, a source transmits its data to a destination via the multi-hop relaying model using the transmit antenna selection (TAS)/selection combining (SC) technique at each hop, in the presence of an eavesdropper who wants to receive the data illegally. The secondary transmitters, including the source and intermediate relays, have to harvest energy from radio-frequency signals of a power beacon for transmitting the source data. Moreover, their transmit power must be adjusted to satisfy the quality of service (QoS) of the primary network. Under the joint impact of hardware imperfection and interference constraint, expressions for the transmit power for the secondary transmitters are derived. We also derive exact and asymptotic expressions of secrecy outage probability (SOP) and probability of non-zero secrecy capacity (PNSC) for the proposed protocol over Rayleigh fading channel. The derivations are then verified by Monte Carlo simulations.Web of Science195art. no. 116

Corporate social responsibility (CSR) situation in Vietnam

While the application of CSR is no longer new to the developed markets, it is unfortunately not the case in developing nations. In particular, Vietnam has seen a mixture of promising and volatile results concerning this topic. Consequently, this thesis was carried out by Mr. Trung Tin Tran to answer the questions of how the CSR situation in Vietnam is currently looking. With that goal set in mind, this thesis topic was tackled by a qualitative approach, in which five case companies were analyzed in terms of their CSR perceptions and strategies. The information for these researches was collected from the companies’ official website, annual report, CSR report and third parties’ resources. In conclusion, the thesis contains a general discussion on the topic of CSR, as well as CSR in developing nations. The most important part of the thesis discusses the perception of five Vietnamese and international enterprises on the topic of CSR and their strategies. The result from this research concludes that the current CSR situation in Vietnam is not all grim but rather contains some very promising signs. The author also points out some solutions to the down side of the CSR situation in Vietnam. Further study on this subject can tackle either CSR practices in Vietnamese SMEs

Rateless codes-based secure communication employing transmit antenna selection and harvest-to-jam under joint effect of interference and hardware impairments

In this paper, we propose a rateless codes-based communication protocol to provide security for wireless systems. In the proposed protocol, a source uses the transmit antenna selection (TAS) technique to transmit Fountain-encoded packets to a destination in presence of an eavesdropper. Moreover, a cooperative jammer node harvests energy from radio frequency (RF) signals of the source and the interference sources to generate jamming noises on the eavesdropper. The data transmission terminates as soon as the destination can receive a sufficient number of the encoded packets for decoding the original data of the source. To obtain secure communication, the destination must receive sufficient encoded packets before the eavesdropper. The combination of the TAS and harvest-to-jam techniques obtains the security and efficient energy via reducing the number of the data transmission, increasing the quality of the data channel, decreasing the quality of the eavesdropping channel, and supporting the energy for the jammer. The main contribution of this paper is to derive exact closed-form expressions of outage probability (OP), probability of successful and secure communication (SS), intercept probability (IP) and average number of time slots used by the source over Rayleigh fading channel under the joint impact of co-channel interference and hardware impairments. Then, Monte Carlo simulations are presented to verify the theoretical results.Web of Science217art. no. 70

Analysis of probability of non-zero secrecy capacity for multi-hop networks in presence of hardware impairments over Nakagami-m fading channels

In this paper, we evaluate probability of non-zero secrecy capacity of multi-hop relay networks over Nakagamim fading channels in presence of hardware impairments. In the considered protocol, a source attempts to transmit its data to a destination by using multi-hop randomize-and-forward (RF) strategy. The data transmitted by the source and relays are overheard by an eavesdropper. For performance evaluation, we derive exact expressions of probability of non-zero secrecy capacity (PoNSC), which are expressed by sums of infinite series of exponential functions and exponential integral functions. We then perform Monte Carlo simulations to verify the theoretical analysis.Web of Science25478277

Secrecy performance enhancement for underlay cognitive radio networks employing cooperative multi-hop transmission with and without presence of hardware impairments

In this paper, we consider a cooperative multi-hop secured transmission protocol to underlay cognitive radio networks. In the proposed protocol, a secondary source attempts to transmit its data to a secondary destination with the assistance of multiple secondary relays. In addition, there exists a secondary eavesdropper who tries to overhear the source data. Under a maximum interference level required by a primary user, the secondary source and relay nodes must adjust their transmit power. We first formulate effective signal-to-interference-plus-noise ratio (SINR) as well as secrecy capacity under the constraints of the maximum transmit power, the interference threshold and the hardware impairment level. Furthermore, when the hardware impairment level is relaxed, we derive exact and asymptotic expressions of end-to-end secrecy outage probability over Rayleigh fading channels by using the recursive method. The derived expressions were verified by simulations, in which the proposed scheme outperformed the conventional multi-hop direct transmission protocol.Web of Science212art. no. 21

Effects of steel corrosion to BFRP Strengthened columns under eccentric loading

The experiment consists of twenty-four mid-scale rectangular RC columns (200x200x800mm) strengthening by BFRP sheets and research variables include: BFRP layer (0, 1, and 3 layers); eccentricity (25mm and 75mm); and 4 levels of steel corrosion. The results reveal that SEL (ratio of ultimate load of strengthened member to that of corresponding controlled member) is direct proportion with steel corrosion while SEV (ratio of ultimate vertical displacement of strengthened member to that of corresponding controlled member) is inverse proportion with steel corrosion; SEL slightly increases with the increase of BFRP layer and eccentricity; but SEV decreases noticeably with the increase of BFRP layer and eccentricity. In addition,the interaction between FRP sheets, stirrups, and longitudinal reinforcement in steel degraded BFRP strengthened columns is very strong.However, column design basing on current design manuals and codes as ACI 440.2R and CNR DT 200R1 has not mentioned this affect. Thus, the load capacity prediction of column being strengthened by BFRP sheets should include levels of steel corrosion for reality, reasonable, and integral of the design

Effects of steel corrosion to BFRP Strengthened columns under eccentric loading

The experiment consists of twenty-four mid-scale rectangular RC columns (200x200x800mm) strengthening by BFRP sheets and research variables include: BFRP layer (0, 1, and 3 layers); eccentricity (25mm and 75mm); and 4 levels of steel corrosion. The results reveal that SEL (ratio of ultimate load of strengthened member to that of corresponding controlled member) is direct proportion with steel corrosion while SEV (ratio of ultimate vertical displacement of strengthened member to that of corresponding controlled member) is inverse proportion with steel corrosion; SEL slightly increases with the increase of BFRP layer and eccentricity; but SEV decreases noticeably with the increase of BFRP layer and eccentricity. In addition,the interaction between FRP sheets, stirrups, and longitudinal reinforcement in steel degraded BFRP strengthened columns is very strong.However, column design basing on current design manuals and codes as ACI 440.2R and CNR DT 200R1 has not mentioned this affect. Thus, the load capacity prediction of column being strengthened by BFRP sheets should include levels of steel corrosion for reality, reasonable, and integral of the design

Workplace wellbeing in community pharmacy practice: A cross-sectional study in Can Tho, Vietnam

Background: Among pharmacy workers, low workplace wellbeing can lead to reduced effectiveness. However, to date, studies on this issue are limited within the community pharmacy setting in Vietnam. Objectives: This study was conducted to identify the component aspects of workplace wellbeing and their associations with demographic characteristics. Methods: The cross-sectional descriptive study was conducted in Can Tho, Vietnam. Self-administered questionnaires were hand-delivered to all pharmacy workers working at selected community pharmacies. The workplace wellbeing scale comprised 18 items. Results: In total, 382 pharmacy workers participated in this study. Factor analysis revealed three fundamental aspects to workplace wellbeing: Factor 1 – perceived self-worth and job satisfaction, Factor 2 – positive emotions with work, and Factor 3 – negative emotions with work. Factor 1 showed a positive correlation with Factor 2, with a correlation coefficient (ρ) of 0.509, while both Factor 1 (ρ = −0.399) and Factor 2 (ρ = −0.416) demonstrated negative correlations with Factor 3. Higher income was associated with higher positive emotions with work (P = 0.008), higher perceived self-worth and job satisfaction (P = 0.013), and lower negative emotions with work (P < 0.001). Conclusion: Workplace wellbeing of pharmacy workers in their professional environments was associated with financial aspects. These findings suggest that policies aimed at improving income for pharmacy workers could bring benefits to enhancing job satisfaction and workplace wellbeing

Power allocation strategies for dual-hop relay protocols with best relay selection under constraint of intercept probability

In this letter, we propose two power allocation strategies, named Optimal Power Allocation (OPA) and Equal Intercept Probability (EIP), for dual-hop cooperative decode-and-forward (DF) relaying networks under constraint of intercept probability (IP). Particularly, with knowledge of channel statistics of the eavesdropping links, the transmitters such as source and relays adjust their transmit power to control the value of IP by a desired level. A max–min relay selection method is applied to enhance the end-to-end outage probability (OP). We derive expressions of transmit power for the source and the selected relay. Then, Monte Carlo simulations were performed to verify analytical results. Keywords: Outage probability, Intercept probability, Decode-and-forward, Relay selectio

Security-reliability analysis of noma-based multi-hop relay networks in presence of an active eavesdropper with imperfect eavesdropping CSI

In this paper, we evaluate system performances of a multi-hop relay protocol with presence of an active eavesdropper. In the proposed protocol, a source attempts to transmit its data to a destination with assistance of multiple intermediate relays. From the eavesdropping Channel State Information (CSI) estimated, the source and relays adjust their transmit power so that the eavesdropper cannot overhear the transmitted data. Moreover, to enhance throughput for the proposed system, Non-Orthogonal Multiple Access (NOMA) technique with a simple power allocation is also proposed. We derive exact closed-form expressions of the Outage Probability (OP) and throughput for the data transmission over Rayleigh fading channel. In addition, when the CSI estimation is imperfect, Intercept Probability (IP) at the eavesdropper is derived. Finally, Monte Carlo simulations are presented to verify the theoretical derivations