Rate-Constrained Wireless Networks with Fading Channels: Interference-Limited and Noise-Limited Regimes

A network of $n$ wireless communication links is considered in a Rayleigh fading environment. It is assumed that each link can be active and transmit with a constant power $P$ or remain silent. The objective is to maximize the number of active links such that each active link can transmit with a constant rate $\lambda$. An upper bound is derived that shows the number of active links scales at most like $\frac{1}{\lambda} \log n$. To obtain a lower bound, a decentralized link activation strategy is described and analyzed. It is shown that for small values of $\lambda$, the number of supported links by this strategy meets the upper bound; however, as $\lambda$ grows, this number becomes far below the upper bound. To shrink the gap between the upper bound and the achievability result, a modified link activation strategy is proposed and analyzed based on some results from random graph theory. It is shown that this modified strategy performs very close to the optimum. Specifically, this strategy is \emph{asymptotically almost surely} optimum when $\lambda$ approaches $\infty$ or 0. It turns out the optimality results are obtained in an interference-limited regime. It is demonstrated that, by proper selection of the algorithm parameters, the proposed scheme also allows the network to operate in a noise-limited regime in which the transmission rates can be adjusted by the transmission powers. The price for this flexibility is a decrease in the throughput scaling law by a multiplicative factor of $\log \log n$.Comment: Submitted to IEEE Trans. Information Theor

A Contribution to the Theory of Rotating Electrical Machines

This contribution introduces a vector interpretation to unify the description of torque development in rotating electrical machines. The motivation behind this attempt is the necessity of applying different physical interpretation and calculation methods, such as Lorentz force, Maxwell stress tensor, co-energy methods etc., for predicting and estimating different torque components, e.g. synchronous torque, oscillating torque, cogging torque, reluctance torque etc., in different rotating electrical machines. The unified vector model describes and estimates the different torque components in rotating electrical machines with an apprehensible concise formulation. Beyond that, the other most frequently used tools and terms in the field of electrical machines, such as Park and Clark transformations, phasor diagram etc., can be derived directly from this model, which has also a simplifying didactic contribution to a conventional course of electrical machines

Characterization of Rate Region in Interference Channels with Constrained Power

In this paper, an $n$-user Gaussian interference channel, where the power of the transmitters are subject to some upper-bounds is studied. We obtain a closed-form expression for the rate region of such a channel based on the Perron-Frobenius theorem. While the boundary of the rate region for the case of unconstrained power is a well-established result, this is the first result for the case of constrained power. We extend this result to the time-varying channels and obtain a closed-form solution for the rate region of such channels.Comment: 21 Pages, The Conference Version is Submitted to IEEE International Symposium on Information Theory (ISIT2007

The Concept of Religious Pluralism in a Globalized World: An Analytical and Comparative Study of John Hick and Hossein Nasr's Theories

Religious pluralism is an increasingly significant phenomenon in our global society. As religious diversity continues to grow, it's essential to understand and appreciate different religious traditions and their beliefs. This thesis aims to contribute to the scholarly discourse on religious pluralism by analyzing and comparing the works of John Hick and Hossein Nasr, two influential scholars in the field. Using a qualitative research approach, the study provides a brief understanding of each scholar's key ideas and arguments and their contributions to the field of religious pluralism. Specifically, the study examines critical concepts such as the doctrine of Incarnation, the concept of primordial tradition, and the esoteric-exoteric dichotomy. The research also investigates Hick's perspective on the relationship between phenomena and noumena and Nasr's ideas on archetypes on the formation of religious belief systems. According to the topics discussed the study analyzes the differences between Hick and Nasr's approaches to religious pluralism particularly in relation to the formation of religion, the knowability of God, and the ethical and metaphysical dimensions of religious pluralism. Hick emphasizes the importance of interfaith dialogue and cooperation in promoting mutual understanding and respect while rejecting exclusivity associated with orthodox interpretations of the doctrine of the Incarnation and proposing a new interpretation. In contrast, Nasr emphasizes the need to preserve each religious tradition's unique identity and integrity. These differing perspectives reveal the complexity of religious pluralism and underscore the importance of continued exploration and dialogue in this area. Overall, this study seeks to enhance our understanding of religious pluralism and its implications for our global society. By providing a brief analysis of Hick and Nasr's works, this thesis can serve as a basis for further research in this area

On the Throughput Maximization in Dencentralized Wireless Networks

A distributed single-hop wireless network with $K$ links is considered, where the links are partitioned into a fixed number ($M$) of clusters each operating in a subchannel with bandwidth $\frac{W}{M}$. The subchannels are assumed to be orthogonal to each other. A general shadow-fading model, described by parameters $(\alpha,\varpi)$, is considered where $\alpha$ denotes the probability of shadowing and $\varpi$ ($\varpi \leq 1$) represents the average cross-link gains. The main goal of this paper is to find the maximum network throughput in the asymptotic regime of $K \to \infty$, which is achieved by: i) proposing a distributed and non-iterative power allocation strategy, where the objective of each user is to maximize its best estimate (based on its local information, i.e., direct channel gain) of the average network throughput, and ii) choosing the optimum value for $M$. In the first part of the paper, the network hroughput is defined as the \textit{average sum-rate} of the network, which is shown to scale as $\Theta (\log K)$. Moreover, it is proved that in the strong interference scenario, the optimum power allocation strategy for each user is a threshold-based on-off scheme. In the second part, the network throughput is defined as the \textit{guaranteed sum-rate}, when the outage probability approaches zero. In this scenario, it is demonstrated that the on-off power allocation scheme maximizes the throughput, which scales as $\frac{W}{\alpha \varpi} \log K$. Moreover, the optimum spectrum sharing for maximizing the average sum-rate and the guaranteed sum-rate is achieved at M=1.Comment: Submitted to IEEE Transactions on Information Theor

Throughput Scaling Laws for Wireless Networks with Fading Channels

A network of n communication links, operating over a shared wireless channel, is considered. Fading is assumed to be the dominant factor affecting the strength of the channels between transmitter and receiver terminals. It is assumed that each link can be active and transmit with a constant power P or remain silent. The objective is to maximize the throughput over the selection of active links. By deriving an upper bound and a lower bound, it is shown that in the case of Rayleigh fading (i) the maximum throughput scales like $\log n$ (ii) the maximum throughput is achievable in a distributed fashion. The upper bound is obtained using probabilistic methods, where the key point is to upper bound the throughput of any random set of active links by a chi-squared random variable. To obtain the lower bound, a decentralized link activation strategy is proposed and analyzed.Comment: Submitted to IEEE Transactions on Information Theory (Revised

Regression to Middle Effect May Threaten Validity of Triage Scales; a Letter to Editor

Triage is sorting patients based on acuity in order to manage care in the emergency department (ED) {Mirhaghi, 2017 #60}(1). Medical institutes are trying to develop triage scales compatible with their own culture of care. A triage scale must be precise and comprehensive enough to guide triage nurses and eliminate uncertainty

The Australasian Triage Scale Level 5 Criteria may Need to be Revised

Australasian Triage Scale (ATS) is used to prioritize incoming patients in the emergency department (ED) according to patient acuity. It`s a five-level triage scale endorsed by the Australasian College for Emergency Medicine (ACEM). The ATS categories are defined by physiological predictors (airway, breathing, circulation, and disability) and maximum waiting time to treatment (1: immediate, 2: 10 minutes, 3: 30 minutes, 4: 60 minutes and 5: 120 minutes). Triage scales should be valid and reliable to ensure safe practice and promote clinical applicability in ED. Ebrahimi et al. reported that the pooled coefficient for ATS is fair: 0.390 (95% CI 0.307–0.466).