136879 research outputs found
Sort by
Design and Measurement of VFD Motor Driven Blower String Subjected to An Electrical Fault
No full textCase Stud
SR Tools: Dreamy or Nighmarish?
Get PDFSystematic review (SR) services are expanding in most libraries as users call on librarians for assistance. The review community continues to develop tools to aid in various aspects of the SR process. But are these tools dreamy or nightmarish? This poster will present a selection of potential tools for systematic review projects, organized by function. Among these tools are resources which aid with term analysis, deduplication, review type selection, and more. Each resource will be evaluated for its utility after thorough testing with actual review projects in an academic medical setting. Conference attendees will have the opportunity to provide feedback on their preferred systematic review tools, and suggest additional tools for consideration
On the Physical Layer Security of Uplink IM-OFDMA Systems Considering IQ Imbalances
Get PDFWireless communication has recently entered ubiquitous connectivity, including the internet of things (IoT), intelligent infrastructures, and cyber-physical systems. Accordingly, the number of wireless nodes and terminals is expected to escalate in the upcoming years in parallel with the ever-increasing demand for higher data rates, emerging applications, and services. Through the development of successive wireless systems generations, the adopted multiple access (MA) schemes have played an efficient role in accommodating the increasing demand for wireless connectivity. However, up to 5G, all employed MA schemes still have a strict limit on the number of served users, where it cannot exceed the number of available orthogonal channels. To this end, new concepts have been introduced as promising solutions to outperform conventional MA schemes. One of these promising solutions, the non-orthogonal multiple access (NOMA) schemes, showed that a group of users can occupy the same channel(s) with a specific encoding technique that assists the receiver in detecting the desired signal. However, another promising NOMA scheme, which is called index modulation-based orthogonal division multiple access (IM-OFDMA), has been recently proposed to provide significant enhancements in the overall spectral efficiency by utilizing the activation states of the building blocks as an extra constellation symbol for information embedding. Uplink IM-OFDMA systems outperform other MA techniques, such as OFDMA and NOMA, regarding bit-error-rate (BER) performance. Moreover, IM-OFDMA can serve three times more users than the conventional OFDMA transmission scheme without sacrificing error performance. Regarding spectral efficiency, it can be precious for one of the main tasks of 5G, which is massive machine-type communication. For this reason, it is also shown as a candidate for 6G networks to yield an increase in spectral efficiency. However, hardware imperfection can severely impact the performance of the IM-OFDMA uplink systems.
On the other hand, security flaws are also a severe concern in wireless communication systems. Conventional confidentiality schemes are based primarily on cryptography and handled at different protocol stack layers. Specifically, regarding secure communications, legitimate parties employ symmetric encryption, such as the advanced encryption standard, which relies on a secret key shared between them beforehand. However, lightweight IoT application devices may need help supporting computationally complex cryptography algorithms. Therefore, these devices��� security must be provided at the physical layer. For these reasons, data confidentiality should be ensured by employing a unique future of transmitter or receiver (e.g., carrier frequency offset, phase noise, and in-phase and quadrature imbalances (IQI)) or artificial noises. Consequently, this dissertation attempts to address three key research areas for uplink IM-OFDMA systems: IQI, physical layer security (PLS), and physical layer authentication (PLA).
In the first part of this dissertation, the individual and joint effects of the transmitter and receiver IQI on the bit-error-rate (BER) performance of the uplink IM-OFDMA scheme are investigated by considering whether each user���s RF front-end is identical or not. Moreover, to reduce the detrimental effect of IQI, a preamble-based estimation and compensation method is derived for IM-OFDMA. In the second part of this dissertation, the secrecy analysis of the IM-OFDMA schemes is addressed by considering the IQI presence at the users��� RF front ends. Particularly, by assuming the existence of an eavesdropper, the secrecy performance of the IM-OFDMA is investigated through the strictly positive secrecy capacity and secrecy outage probability, and closed-form expressions are derived for both quantities. Then, the secure uplink IM-OFDMA scheme is introduced in the third section of the dissertation. Finally, in the fourth section of the dissertation, the PLA for IM-OFDMA systems is investigated considering IQI, and a dual-phase malicious user detection scheme for IM-OFDMA is expressed
Red Imported Fire Ants in the Brown Food Web: Ecological, Behavioral, and Nutritional Mechanisms Underlying the Recruitment of Solenopsis invicta to Vertebrate Carrion
Get PDFThis dissertation highlights the overlooked involvement of ants in vertebrate carrion decomposition. Insects such as flies and beetles have long been recognized as significant players in vertebrate carrion decomposition due to their roles as prolific primary colonizers and voracious biomass consumers. Ants, on the other hand, while being commonly recognized as opportunistic scavengers, have never been systematically studied in the context of decomposition ecology.
We therefore propose an interdisciplinary investigation articulated around three questions: What is the prevalence of vertebrate carrion consumption by ants? What in carrion is attractive to ants? What are the benefits associated with the recruitment to vertebrate carrion?
We conducted an extensive literature review, uncovering records of 154 ant species engaging with vertebrate carrion across various habitats and continents. We found that ants��� impact vertebrate carrion decomposition through both direct and indirect mechanisms. The direct effects encompass necrophagy and carcass laceration, while indirect effects entail predation on carrion-feeding invertebrates and microhabitat alterations through nesting activities. Our empirical research focused on the red imported fire ant (Solenopsis invicta) as a model species. Through a combination of field and laboratory experiments, our data confirmed that fire ants readily recruit to vertebrate carrion, but when consumed, it proved to be detrimental to colony performance. We hypothesize that while being attracted to vertebrate carrion, the main nutritional resource for the ants is not the carcass, but the dipteran larvae feeding on it. We also identified dimethyl disulfide (DMDS), a volatile organic compound (VOCs) emitted during vertebrate carrion decomposition, as a key attractant to vertebrate carrion, both in controlled laboratory settings and in the field. Then, we compared the nutritional benefits of a vertebrate carrion diet compared to a vertebrate carrion-feeding maggot diet and revealed the importance of fatty acid intake regulation in ants.
By its interdisciplinary approach, this dissertation paves the way for future research aiming to elucidate the complex relationships between green and brown food webs and offers valuable insights for the fields of ecology and forensics, ultimately contributing to a more holistic understanding of vertebrate carrion decomposition