Perfect Case Research Articles

The effects of channel knowledge on cooperative spectrum sensing in Nakagami-n/q fading channels

Cooperative spectrum sensing (CSS) is an efficient method to detect vacant spectrum of a primary user (PU) by combining sensing information of multiple cognitive radios (CRs) in presence of fading. In this paper, effects of perfect and imperfect channel state information (CSI) on CSS network is evaluated. The proposed network is operated over Nakagami-q (Hoyt) and Nakagami-n (Rician) fading affecting both reporting (R) and sensing (S) channels. The CRs which employ energy detectors (EDs) are selected on the basis of CSI between them and a fusion center (FC). The knowledge on the quality of R-channels is estimated at FC using a channel estimator. The estimated CSI is either perfect when there is no error in the estimator, or imperfect when errors are present. Accordingly, CRs are selected under both perfect CSI and imperfect CSI cases. All CRs use the decision statistics obtained by EDs and make one-bit binary decisions about the availability of a PU. Selected CRs only transmit decision information to the FC. The miss detection probability and error rate of network under two cases of selection are evaluated by operating majority and maximal ratio combining rules at the FC. Performance is analyzed for different channel and network parameters and comparison between fusion rules for different fading channels is also highlighted.

Resource Allocations for Secure Cognitive Satellite-Terrestrial Networks

Cognitive satellite-terrestrial networks (STNs) have been recognized as the promising architecture for addressing spectrum scarcity in the next generation communication networks. In this letter, we investigate the secure transmission schemes in the cognitive STNs where the interference from terrestrial base station (BS) is introduced to enhance security of the satellite link. Our objectives are to minimize the transmit power by jointly optimizing the cooperative beamforming and artificial noise (AN) while guaranteeing the secrecy rate constraint for satellite link, the information rate constraint for terrestrial link and the total transmit power constraint. Both scenarios of the perfect and imperfect channel cases are respectively considered. These constraints make the optimization problems formulated non-convex and challenging, which are efficiently solved via certain transformations to be formulated more tractable versions, respectively. Numerical results are provided to corroborate the proposed schemes.

Tectonic controls of Late Cenozoic monogenetic intraplate volcanism at the Wulanhada volcanic field, Northern China

The role of India-Eurasian collision and Western-Pacific subduction on the formation of intraplate volcanoes in East Asian is unclear. Wulanhada in North China is a perfect study case for this problem as an intraplate monogenetic volcanic field. We identified 18 volcanoes and 41 vents in Wulanhada volcanic field and divided them into three groups according to notably spatial alignments. Geochemical data show the three groups have similar characteristics in rock classification and trace element patterns. Consequently, the three groups of volcanoes could be treated as one volcanic system. Our K-Ar age data indicate that the volcanism in WVF occurred since the late Miocene and lasted until Quaternary. The feeder fractures far from the W-G fault generally strike ENE-NE, consistent with the maximum principal compressive stress of this region, while the feeder fractures near the W-G fault trend WNW, subparallel to this pre-existing fault. Based on the couplings of stress field and feeder dyke in orientation and timing consistency between the India-Eurasian collision and the volcanism at Wulanhada, the tectonic control from the Tibet Plateau is a dominant factor on the volcanism at WVF. The W-G fault is another indispensable factor for concentration of stress and the distribution of volcanoes at WVF.

Not All Roads Lead to Rome: The Conditional Effect of Legislative Activity on Reselection Prospects in Italy

The literature shows that, on average, electorally vulnerable Members of Parliament (MPs) are more active than their colleagues. This article investigates whether parties have an incentive to reselect active MPs in a county with a closed-list electoral system. Being active is usually a way to increase one’s visibility among the constituency. We argue that parties have incentives to reselect active MPs only when they believe that voters pay attention to the qualities of individual candidates. The Italian case is a perfect case to test this argument because the attention paid by voters to individual candidates varies significantly between the northern and southern regions. Our empirical analysis reveals that being active leads to a higher probability to be re-selected only in regions where the style of representation is personalised.

Faulkner and Print Culture ed. by Jay Watson, Jaime Harker, and James G. Thomas

Reviewed by: Faulkner and Print Culture ed. by Jay Watson, Jaime Harker, and James G. Thomas Anna Creadick Faulkner and Print Culture. Edited by Jay Watson, Jaime Harker, and Jamesc G. Thomas Jr. (Jackson: University Press of Mississippi, 2017. Pp. xxxii, 241. $65.00, ISBN 978-1-4968-1230-8.) Historians have traditionally been interested in William Faulkner largely because Faulkner was interested in history. Faulkner's works take up the past, especially the southern past, as setting, theme, and even philosophy, as in the oft-quoted line from Requiem for a Nun (1951), "The past is never dead. It's not even past." Refreshingly, Faulkner and Print Culture allows historians to consider how Faulkner's career itself constitutes a meaningful historical subject. With a life and work spanning the first two-thirds of the twentieth century, Faulkner had experiences with modern print culture that help tell a broader American story. For scholars working in Faulkner studies, the [End Page 1030] collection is essential because it reconnects the author to the forces that shaped him and that he helped shape. For historians, southernists, and other Americanists, Faulkner and Print Culture helps reveal how deeply books and the print industries shaped the twentieth century. Faulkner and Print Culture is both timely and pertinent to contemporary work not only in literary studies but also in book history, periodical studies, critical modernisms, and new regionalism. Drawn from papers presented at the lively annual Faulkner and Yoknapatawpha Conference in Oxford, Mississippi, the text is edited by a triad that ably supports its broad reach: Jay Watson, himself at the epicenter of Faulkner studies at the University of Mississippi; Jaime Harker, an expert in middlebrow and LGBTQ literary history; and James G. Thomas Jr., an editor and publisher on southern culture writ large. While some may imagine that the annual Faulkner conference features literary criticism alone, it offers a more complicated terrain in any year, but exceptionally so in 2015, when Faulkner and print culture was the theme. This resulting collection features scholars of Cold War culture (Greg Barnhisel), middlebrow literary culture (Harker and Yung-Hsing Wu), working-class and genre fiction (Erin A. Smith), book history and historical reception studies (Jay Satterfield and Sarah E. Gardner), film studies (Robert Jackson), periodical studies (Kristi Rowan Humphreys and Jennifer Nolan), biography (Carl Rollyson), and, yes, literary modernism (Kristin Fujie, John N. Duvall, Tim A. Ryan, and Mary A. Knighton). One strength of the collection is its embrace of an "ecumenical approach" (p. xvi). After an opening cluster of six essays that take up the notorious novel Sanctuary (1931) as the perfect print culture case study, the remaining eight essays focus on a range of subjects spanning Faulkner's literary career from the 1930s through the 1950s. It makes sense for this collection to linger somewhat on the "horror" of the "potboiler" Sanctuary (pp. 11, 5). As the contributors show, the novel became the subject of its own critical fictions, but it should actually be understood as the work that best integrated Faulkner's brow-busting audience appeal: it was the "B-side" enjoyed even more than the hit single (p. xix). The collection is richly multidisciplinary, featuring, for example, the work of historians such as Sarah E. Gardner, whose essay on Sanctuary's reception illuminates the relationships between criticism and regionalism at this time. The collection also foregrounds work that is deeply historicist. Mary A. Knighton's essay, for example, is as much about the synergy of book illustration, modernist satire/parody, and the literary/artistic community in the interwar years as it is about Faulkner. Insofar as the essay resituates the author in the complicated swirl of art, influence, and the surprising irreverence of international modernism, it is a Faulkner essay. The revelations of the collected essays entice the reader. With every chapter, we want to know more of this other Faulkner: the one who came in second in an Ellery Queen mystery writing competition, a feat that did at least as much for his career as Malcolm Cowley did, according to John N. Duvall. How many know that Faulkner was cast as an "American Tolstoy" and mobilized by the State Department to join the...

Power Allocation for Multi-Way Massive MIMO Relaying

We consider a multi-way decode-and-forward relaying network with very large antenna arrays at the relay station. In this system, each user and the relay operate in half-duplex and time-division duplexing modes. To exchange information among all users, we propose a new transmission protocol which combines massive multiple-input multiple-output technology with linear processing, self-interference cancelation, and successive cancelation decoding. Our proposed transmission protocol reduces the number of time-slots for data exchange among users by approximately 2 times, compared with the conventional data transmission protocol. For this new topology, we derive a very tight approximation of the spectral efficiency in closed-form assuming perfect channel state information (CSI). Then, a CSI acquisition method at the relay and the users is provided and analyzed. We show via numerical simulations, that the performance gap between imperfect and perfect CSI cases is small. The closed-form expression of the spectral efficiency enables us to design two power allocation schemes. In the first power allocation scheme, we choose the transmit powers at the users and the relay to maximize the sum spectral efficiency, subject to a given quality-of-service requirement for each user. In the second power allocation scheme, the objective is the energy efficiency taking into account the hardware power consumption. Both power allocation schemes can be efficiently executed by iteratively solving a sequence of convex problems. Numerical results verify the effectiveness of the proposed transmission protocol and the power allocation schemes compared with the state of the art.

Queueing Stability and CSI Probing of a TDD Wireless Network With Interference Alignment

This paper characterizes the performance in terms of queueing stability of a network composed of multiple MIMO transmitter-receiver pairs taking into account the dynamic traffic pattern and the probing/feedback cost. We adopt a centralized scheduling scheme that selects a number of active pairs in each time-slot. We consider that the transmitters apply interference alignment (IA) technique if two or more pairs are active, whereas in the special case where one pair is active point-to-point MIMO singular value decomposition (SVD) is used. We consider a time-division duplex (TDD) system where transmitters acquire their channel state information (CSI) by decoding the pilot sequences sent by the receivers. Since global CSI knowledge is required for IA, the transmitters have also to exchange their estimated CSIs over a backhaul of limited capacity (i.e. imperfect case). Under this setting, we characterize in this paper the stability region of the system under both the imperfect and perfect (i.e. unlimited backhaul) cases, then we examine the gap between these two resulting regions. Further, under each case we provide a centralized probing policy that achieves the max stability region. These stability regions and scheduling policies are given for the symmetric system, where all the path loss coefficients are equal to each other, as well as for the general system. For the symmetric system, we provide the conditions under which IA yields a queueing stability gain compared to SVD. Under the general system, the adopted scheduling policy is of a high computational complexity for moderate numbers of pairs, consequently we propose an approximate policy that has a reduced complexity but that achieves only a fraction of the system stability region. A characterization of this fraction is provided.

Asynchronous data assimilation with the EnKF in presence of additive model error

The term ‘asynchronous data assimilation’ (ADA) refers to modifications of sequential data assimilation methods that take into consideration the observation time. In Sakov et al. [Tellus A, 62, 24–29 (2010)], a simple rule has been formulated for the ADA with the ensemble Kalman filter (EnKF). To assimilate scattered in time observations, one needs to calculate ensemble forecast observations using the forecast ensemble at observation time. Using then these ensemble observations in the EnKF update matches the optimal analysis in the linear perfect model case. In this note, we generalise this rule for the case of additive model error.

Smart Wall Painting System

The objective of this paper is to outline a smart wall painting system for little and medium scale operations. These days robots are broadly utilized as a part of relatively every application like medicinal application, amusement, military, production lines vehicle businesses, and so on. However, the utilization of robot is as yet not generally utilized as a part of constructional work. Robots are fundamentally design to build speed and maximize accuracy of construction field work. The basic point of the paper is to design, develop and actualize Remote Operated Wall Painting Machine which helps for accomplishing painting hardware requiring little to no effort because of which the sketch work can be effectively done proficiently and in particular at extremely ostensible cost. The painting machine keeps away from coordinate contact of chemicals which can be harmful to the human painters, for example, eye, skin and respiratory system issues.. Besides that the idea of painting method that requires rehashed work time and hand rising make it physical torment, and exertion devouring. Moreover, it would offer the chance to decrease or take out human introduction to troublesome and dangerous worked system conditions, which would take care of a large portion of the issues associated with security when numerous activities happen in the meantime. This machine is is easy to operate and no need of labour required to operate effectively. At the point when development specialists and robots are appropriately coordinated in building tasks,the entire development process can be better overseen and savings in human work and timing are acquired as an outcome. wall painting is a redundant, debilitating and risky process which makes it a perfect case for automation. Painting had been mechanized in car industry however not yet for the development business. There is a strong requirement for a portable robot that can move to paint walls of buildings. In this paper, the conceptual plan of a an autonomous wall painting robot is portrayed comprising of an arm that sweeps the dividers vertically and is fitted on a versatile robot base to give the lateral feed movement to cover the painting area. The design objective is to fulfill the criteria of straight forwardness, low weight, ease and quick painting time. Ultrasonic sensors are fitted on the arm and the portable base to alter as far as possible and move in the room territory. A control system is intended to direct the arm movement and plan the versatile base movement.

Coordination on Networks

We study a coordination game among agents on a network, who choose whether or not to take an action in an uncertain environment that yields value increasing in the actions of neighbors. We develop an algorithm that fully characterizes the equilibrium partitions (coordination sets) and thresholds using the primitives of the model. We show that there is a single coordination set if and only if the network is balanced, i.e., the average degree of each subnetwork is no larger than the average degree of the network. Comparative statics exercises as well as welfare properties are investigated. In particular, we show that contagion is localized within coordination sets. Compared to the perfect information case, both the equilibrium selection, the comparative statics properties as well as the policy implications are different.

A Control Oriented Perspective for Security in Connected and Automated Vehicles

This article provides an overview of the potential attacks that can impact connected vehicles (CV) technologies and highlights how a resilient control scheme can be effective to mitigate the effect of these attacks by allowing the system to safely operate with reduced performance. CVs endure several challenges that can occur due to cyberattacks with purposes of disrupting the performance of the connected vehicles system. To improve safety and security, advanced vehicular control systems must be designed to be resilient to cyberattacks. The attack detection and switching strategy is formulated as an MPC-like optimization problem, where the control variable is constrained to a specific strategy and applied in a receding horizon fashion. The choice of the cost function plays an important role in the performance of the system. The results of the switching strategy show that in comparison with the perfect case—in which the attacks are perfectly identified and the correct strategy selected immediately—there is approximately a 22 percent strategy improvement that could still be achieved by changing the switching strategy.

A Hybrid Optimization Approach for Interference Alignment in Multi-User MIMO Relay Networks Under Different CSI

For the next generation of wireless communication network, a heterogeneous network architecture with macro cells, small cells, and relays offers numerous advantages, such as higher spectrum efficiency, better fairness in resource allocation, and energy efficient usage as well as optimal coverage. However, this approach encounters various network management challenges, including interference mitigation techniques. In this paper, we consider a multi-user half-duplex amplify-and-forward-MIMO relay system, where a macro basis station communicates with edge cell users via relays and each node has multiple antennas. In this context, we propose two interference alignment (IA) schemes, for which a hybrid approach of the problem formulation based on zero-forcing (ZF) and minimum-mean-square-error optimization criteria was developed to deal with interferences in perfect and imperfect channel state information (CSI) cases. In the case of perfect CSI, simulation results show that this approach provides a SNR gain of about 4 dB regarding BER performance in comparison to that achieved by the reference approach, where all filters are determined solely based on ZF criterion. Furthermore, the achieved capacity and effective signal-to-interference-plus-noise ratio at each edge node are improved by around 5 dB. Having CSI errors, the system performance is significantly improved using the robust design IA approach by minimizing the expected value of cost functions.

Cooperative Full Duplex Device to Device Communication Underlaying Cellular Networks

Recently, device-to-device (D2D) communication and full duplex communication are both considered key technologies for 5G networks. In this paper, two novel cooperative modes are developed for full duplex D2D communication underlaying cellular networks: the network MU-MIMO based mode (N-mode) and the sequential forwarding mode (S-mode). In the N-mode, two D2D users work as network MIMO to forward the data to cellular users and thus leverage the channel diversity. In the S-mode, the spatial distribution of D2D users and cellular users is explored to improve the transmission rate. Based on these modes, two D2D users share the downlink resources with two nearby cellular users simultaneously to achieve both proximity gain and reuse gain. Moreover, these modes are well suited for edge cellular users. To optimize the performance of the two modes, optimal power allocation is conducted by considering the influence of residual self-interference at full duplex radios and the requirements of the minimum transmission rate for both cellular users and D2D users. Simulation results show that, compared with the dedicated mode, the sum rate of cooperative modes in the perfect self-interference cancellation case can achieve 32% overall improvement and about 70% improvement in the scenario with non-edge D2D users and edge cellular users. With residual self-interference at a full duplex radio, the overall performance improvement is reduced to 15%. However, the cooperative modes can still achieve 40% improvement in the scenario with non-edge D2D users and edge cellular users.

Groups in which every non-nilpotent subgroup is self-normalizing

We study the class of groups having the property that every non-nilpotent subgroup is equal to its normalizer. These groups are either soluble or perfect. We describe soluble groups and finite perfect groups with the above property. Furthermore, we give some structural information in the infinite perfect case.

Dynamical localization and the effects of aperiodicity in Floquet systems

We study the localization aspects of a kicked non-interacting one-dimensional (1D) quantum system subject to either time-periodic or non-periodic pulses. These are reflected as sudden changes of the onsite energies in the lattice with different modulations in real space. When the modulation of the kick is incommensurate with the lattice spacing, and the kicks are periodic, a well known dynamical localization in real space is recovered for large kick amplitudes and frequencies. We explore the universality class of this transition and also test the robustness of localization under deviations from the perfect periodic case. We show that delocalization ultimately sets in and a diffusive spreading of an initial wave packet is obtained when the aperiodicity of the driving is introduced.

NOMA in Downlink SDMA With Limited Feedback: Performance Analysis and Optimization

In this paper, the performance of non-orthogonal multiple access (NOMA) is investigated and optimized in a downlink space division multiple access network with a multi-antenna base station and randomly deployed users, under a general channel state information (CSI) limited feedback framework. We first propose a dynamic user scheduling and grouping strategy by leveraging limited feedback. Based on that, an analytical framework is proposed to obtain the outage probability of the network in closed form. The diversity order and the impacts of the number of feedback bits on the outage performance of NOMA are analyzed. Furthermore, the net throughput, which captures the network-wide throughput with the uplink feedback cost considered, is maximized by optimizing the number of feedback bits. Numerical results are demonstrated to verify our analytical findings and show that different from the perfect CSI case, there always exists a performance floor of outage probability in the considered network due to limited feedback. Moreover, the optimal number of feedback bits for net throughput maximization increases as the channel coherence time becomes longer.

Crusading and matrimony in the dynastic policies of Montferrat and Savoy

The uses of matrimony have always been standard practices for dynastic advancement through the ages. A perfect case study involves two important Italian families whose machinations had local implications and widespread international extensions. Their competitions are given particular point by the fact that one of the two families, the House of Savoy, was destined to become the dynasty around which the Modern State of Italy was created.

Coastal debris survey in a Remote Island of the Chilean Northern Patagonia

Global marine litter pollution is increasing dramatically, and oceanic islands are one of the most vulnerable ecosystems due to their high debris accumulation rate compared to continental sites. Remote areas, such as inhabited islands, represent a perfect study case to track marine debris sources, due to the assumed low rates of local production of debris. Guafo Island is one of the largest islands of the Chilean Northern Patagonia and is considered a remote zone. The accessible coast of Guafo Island was monitored during four austral summers revealing higher levels of marine debris accumulation than continental Chile. Plastic was the most abundant type of debris constituting 50% of the total litter monitored. Our results suggest that most of the plastic identified is likely to be related to local fisheries activities. Mitigation measures including collaboration among fishing communities and scientists could contribute to reduce the coastal debris pollution in remote areas.

Microanalytical study of luster glazed gilding and silvering from Baroque altarpieces

Abstract Lustering, a technique which involved the application of coloured translucent glazes over gilding and silvering was widely used to enrich and decorate altarpieces in the Baroque period. The decorations consist of a micrometric multilayered structure including several color glazes, metallic leaves and bole applied over a plaster ground. The collection of Baroque altarpieces, the oldest dating 1671 and the newest 1775 from the cathedral of Tortosa (Catalonia), is a perfect case of study of the materials used and the techniques employed throughout the period. Further information is obtained from the analysis of the reaction and aging compounds resulting from the interaction among the compounds present in the layers and between the different layers. A combination of sensitive analytical techniques, Synchrotron based μ-XRD and μ-IR and SEM-EDS which enabled the luster samples to undergo analysis without altering their original layered microstructure were selected. The nature of the compounds used to produce the yellow, green, red and blue glazes (pigments, pigment lakes and resins), metallic leaves and boles is presented. Relevant information from historical and conservation viewpoints about the origin and nature of the materials used, the making of the lusters and their reactivity and aging are also discussed.

On nonlinear stability of fluid-conveying imperfect micropipes

Micropipe conveying fluid as a core element can be found in many microfluidic devices. In such scale, size effect phenomenon in micropipe may play a significant role in the mechanical behavior of system. In addition, due to the improper production process, the micropipe may be fabricated with a geometric imperfection. Hence, this study objects to investigation of the size-dependent and -independent stability behavior of geometrically perfect and imperfect extensible micropipe conveying fluid under different boundary conditions. In the framework of modified couple stress theory, the nonlinear equations of system are established based on Euler-Bernoulli beam theory. Statics-based analytical solutions are developed to study the nonlinear stability characteristics of system. The statics-based results are verified by aid of a dynamics-based numerical solution. It is indicated that for a perfect case the system becomes unstable at a critical velocity via a pitchfork bifurcation. But, for an imperfect case the system may lose its stability at a primary critical velocity by a perturbed pitchfork bifurcation also it becomes unstable at a secondary critical velocity by a transcritical bifurcation. It is found that the primary and secondary critical velocities of the imperfect case are, respectively, smaller and greater than the critical velocity of the perfect case. A parametric study is conducted to highlight the influence of different dimensionless parameter as well as boundary conditions on the nonlinear stability behavior of system. Finally, it should be pointed out that the analytical solution and the presented results not only for the size-dependent pipe conveying fluid in micro scale but also for the size-independent pipe conveying fluid from macro to micro scale can be utilized.