113 research outputs found
A Distributed Game-Theoretic Solution for Power Management in the Uplink of Cell-Free Systems
This paper investigates cell-free massive multiple input multiple output
systems with a particular focus on uplink power allocation. In these systems,
uplink power control is highly non-trivial, since a single user terminal is
associated with multiple intended receiving base stations. In addition, in
cell-free systems, distributed power control schemes that address the inherent
spectral and energy efficiency targets are desirable. By utilizing tools from
game theory, we formulate our proposal as a noncooperative game, and using the
best-response dynamics, we obtain a distributed power control mechanism. To
ensure that this power control game converges to a Nash equilibrium, we apply
the theory of potential games. Differently from existing gamebased schemes,
interestingly, our proposed potential function has a scalar parameter that
controls the power usage of the users. Numerical results confirm that the
proposed approach improves the use of the energy stored in the battery of user
terminals and balances between spectral and energy efficiency.Comment: Accepted at IEEE Globecom 202
Efficient Battery Usage in Wireless-Powered Cell-Free Systems with Self-Energy Recycling
This paper investigates wireless-powered cell-free systems, in which the
users send their uplink data signal while simultaneously harvesting energy from
network nodes and user terminals - including the transmitting user terminal
itself - by performing self-energy recycling. In this rather general setting, a
closed-form lower bound of the amount of harvested energy and the achieved
signal-to-interference-plus-noise ratio expressions are derived. Then, to
improve the energy efficiency, we formulate the problem of minimizing the
users' battery energy usage while satisfying minimum data rate requirements.
Due to the non-convexity of the problem, a novel alternating optimization
algorithm is proposed, and its proof of convergence is provided. Finally,
numerical results show that the proposed method is more efficient than a
state-of-art algorithm in terms of battery energy usage and outage rate.Comment: Accepted as a correspondance at IEEE TV
Mixed Coherent and Non-Coherent Transmission for Multi-CPU Cell-Free Systems
Existing works on cell-free systems consider either coherent or non-coherent
downlink data transmission and a network deployment with a single central
processing unit (CPU). While it is known that coherent transmission outperforms
noncoherent transmission when assuming unlimited fronthaul links, the former
requires a perfect timing synchronization, which is practically not viable over
a large network. Furthermore, relying on a single CPU for geographically large
cell-free networks is not scalable. Thus, to realize the expected gains of
cellfree systems in practice, alternative transmission strategies for realistic
multi-CPU cell-free systems are required. Therefore, this paper proposes a
novel downlink data transmission scheme that combines and generalizes the
existing coherent and non-coherent transmissions. The proposed transmission
scheme, named mixed transmission, works based on the realistic assumption that
only the access points (APs) controlled by a same CPU are synchronized, and
thus transmit in a coherent fashion, while APs from different CPUs require no
synchronism and transmit in a non-coherent manner. We also propose extensions
of existing clustering algorithms for multi-CPU cell-free systems with mixed
transmission. Simulation results show that the combination of the proposed
clustering algorithms with mixed transmission have the potential to perform
close to the ideal coherent transmission.Comment: Submitted for possible publication in IEEE conferenc
Angular and Current-Target Correlations in Deep Inelastic Scattering at HERA
Correlations between charged particles in deep inelastic ep scattering have
been studied in the Breit frame with the ZEUS detector at HERA using an
integrated luminosity of 6.4 pb-1. Short-range correlations are analysed in
terms of the angular separation between current-region particles within a cone
centred around the virtual photon axis. Long-range correlations between the
current and target regions have also been measured. The data support
predictions for the scaling behaviour of the angular correlations at high Q2
and for anti-correlations between the current and target regions over a large
range in Q2 and in the Bjorken scaling variable x. Analytic QCD calculations
and Monte Carlo models correctly describe the trends of the data at high Q2,
but show quantitative discrepancies. The data show differences between the
correlations in deep inelastic scattering and e+e- annihilation.Comment: 26 pages including 10 figures (submitted to Eur. J. Phys. C
Can large scintillators be used for solar-axion searches to test the cosmological axion-photon oscillation proposal?
Solar-axion interaction rates in NaI, CsI and Xe scintillators via the
axio-electric effect were calculated. A table is presented with photoelectric
and axioelectric cross sections, solar-axion fluxes, and the interaction rates
from 2.0 to 10.0 keV. The results imply that annual-modulation data of large
NaI and CsI arrays, and large Xe scintillation chambers, might be made
sensitive enough to probe coupling to photons at levels required to explain
axion-photon oscillation phenomena proposed to explain the survival of
high-energy photons traveling cosmological distances. The DAMAA/LIBRA data are
used to demonstrate the power of the model-independent annual modulation due to
the seasonal variation in the earth sun distance.Comment: 7 pages and no figure
Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)
In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field
Flexible pay systems and labour productivity: evidence from Emilia Romagna manufacturing firms
The aim of this paper is to analyse the link between flexible pay systems (FPS) and labour productivity, with a close look at wage premium determinants as elements disclosing specific managerial strategies. The analysis was conducted on a sample of more than 500 manufacturing firms located in the Emilia-Romagna region, Italy. Results show that the adoption of flexible pay schemes is linked to union involvement and organizational changes within the firm, supporting the idea that flexible wages do not constitute merely an economic premium, but a more complex strategy aimed at increasing employees\u2019 flexibility and autonomy. Notwithstanding the positive effects on productivity, the relation with economic performance does not emerge as extremely innovative. On the one hand, it is driven by a traditional form of premiums (PRP) targeted to individual employees and linked to a simple \u201ceffort improvement and control\u201d motivation and \u201cability to pay\u201d of the firm. On the other, it is driven by premiums (PFP) provided ex-ante and aimed at developing employees\u2019 participation and competencies
A real-time MAC protocol for in-vehicle power line communications based on HomePlug GP
This paper proposes a new media access control (MAC) protocol for in-vehicle power line communications (PLC). Specifically, the proposed protocol is based on the HomePlug Green PHY (HomePlug GP) which is a modern PLC protocol standard for Smart Grid applications on the Home Area Network [1], however, it has been found that current HomePlug protocols would not cope with the strict timing requirements of in-vehicle communication systems. This paper suggests improvements and modifications to enhance the real-time MAC performance of HomePlug GP in an in-vehicle network through additional priority levels and reduced message length. Simulation results based on the open source network simulator OMNeT++ are provided to show advantages of the proposed protocol
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