4,902 research outputs found
A Note on Gorenstein Flat Dimension
Unlike the Gorenstein projective and injective dimensions, the majority of
results on the Gorenstein flat dimension have been established only over
Noetherian (or coherent) rings. Naturally, one would like to generalize these
results to any associative ring. In this direction, we show that the Gorenstein
flat dimension is a refinement of the classical flat dimension over any ring;
and we investigate the relations between the Gorenstein projective dimension
and the Gorenstein flat dimension
Weak Gorenstein global dimension
In this paper, we investigate the weak Gorenstein global dimensions. We are
mainly interested in studying the problem when the left and right weak
Gorenstein global dimensions coincide. We first show, for GF-closed rings, that
the left and right weak Gorenstein global dimensions are equal when they are
finite. Then, we prove that the same equality holds for any two-sided coherent
ring. We conclude the paper with some examples and a brief discussion of the
scope and limits of our results
Gorenstein Global Dimensions and Cotorsion Dimension of Rings
In this paper, we establish, as a generalization of a result on the classical
homological dimensions of commutative rings, an upper bound on the Gorenstein
global dimension of commutative rings using the global cotorsion dimension of
rings. We use this result to compute the Gorenstein global dimension of some
particular cases of trivial extensions of rings and of group rings
Global Gorenstein dimensions
In this paper, we prove that the global Gorenstein projective dimension of a
ring is equal to the global Gorenstein injective dimension of , and that
the global Gorenstein flat dimension of is smaller than the common value of
the terms of this equality.Comment: 4 page
Derivations and the first cohomology group of trivial extension algebras
In this paper we investigate in details derivations on trivial extension
algebras. We obtain generalizations of both known results on derivations on
triangular matrix algebras and a known result on first cohomology group of
trivial extension algebras. As a consequence we get the characterization of
trivial extension algebras on which every derivation is inner. We show that,
under some conditions, a trivial extension algebra on which every derivation is
inner has necessarily a triangular matrix representation. The paper starts with
detailed study (with examples) of the relation between the trivial extension
algebras and the triangular matrix algebras.Comment: Mediterranean Journal of Mathematics; 201
On n-Perfect Rings and Cotorsion Dimension
A ring is called -perfect (), if every flat module has projective
dimension less or equal than . In this paper, we show that the
-perfectness relate, via homological approach, some homological dimension of
rings. We study -perfectness in some known ring constructions. Finally,
several examples of -perfect rings satisfying special conditions are given
A new approach to muscle fatigue evaluation for Push/Pull task
Pushing/Pulling tasks is an important part of work in many industries.
Usually, most researchers study the Push/Pull tasks by analyzing different
posture conditions, force requirements, velocity factors, etc. However few
studies have reported the effects of fatigue. Fatigue caused by physical
loading is one of the main reasons responsible for MusculoSkeletal Disorders
(MSD). In this paper, muscle groups of articulation is considered and from
joint level a new approach is proposed for muscle fatigue evaluation in the
arms Push/Pull operations. The objective of this work is to predict the muscle
fatigue situation in the Push/Pull tasks in order to reduce the probability of
MSD problems for workers. A case study is presented to use this new approach
for analyzing arm fatigue in Pushing/Pulling.Comment: 19th CISM-IFToMM Symposium on Robot Design, Dynamics, and Control,
Paris : France (2012
Rings over which all modules are strongly Gorenstein projective
One of the main results of this paper is the characterization of the rings
over which all modules are strongly Gorenstein projective. We show that these
kinds of rings are very particular cases of the well-known quasi-Frobenius
rings. We give examples of rings over which all modules are Gorenstein
projective but not necessarily strongly Gorenstein projective
Context-Aware Mobility Management in HetNets: A Reinforcement Learning Approach
The use of small cell deployments in heterogeneous network (HetNet)
environments is expected to be a key feature of 4G networks and beyond, and
essential for providing higher user throughput and cell-edge coverage. However,
due to different coverage sizes of macro and pico base stations (BSs), such a
paradigm shift introduces additional requirements and challenges in dense
networks. Among these challenges is the handover performance of user equipment
(UEs), which will be impacted especially when high velocity UEs traverse
picocells. In this paper, we propose a coordination-based and context-aware
mobility management (MM) procedure for small cell networks using tools from
reinforcement learning. Here, macro and pico BSs jointly learn their long-term
traffic loads and optimal cell range expansion, and schedule their UEs based on
their velocities and historical rates (exchanged among tiers). The proposed
approach is shown to not only outperform the classical MM in terms of UE
throughput, but also to enable better fairness. In average, a gain of up to
80\% is achieved for UE throughput, while the handover failure probability is
reduced up to a factor of three by the proposed learning based MM approaches
Context-Aware Scheduling of Joint Millimeter Wave and Microwave Resources for Dual-Mode Base Stations
One of the most promising approaches to overcome the drastic channel
variations of millimeter wave (mmW) communications is to deploy dual-mode base
stations that integrate both mmW and microwave (\muW) frequencies. Reaping the
benefits of a dual-mode operation requires scheduling mechanisms that can
allocate resources efficiently and jointly at both frequency bands. In this
paper, a novel resource allocation framework is proposed that exploits users'
context, in terms of user application (UA) delay requirements, to maximize the
quality-of-service (QoS) of a dual-mode base station. In particular, such a
context-aware approach enables the network to dynamically schedule UAs, instead
of users, thus providing more precise delay guarantees and a more efficient
exploitation of the mmW resources. The scheduling of UAs is formulated as a
one-to-many matching problem between UAs and resources and a novel algorithm is
proposed to solve it. The proposed algorithm is shown to converge to a
two-sided stable matching between UAs and network resources. Simulation results
show that the proposed approach outperforms classical CSI-based scheduling in
terms of the per UA QoS, yielding up to 36% improvement. The results also show
that exploiting mmW resources provides significant traffic offloads reaching up
to 43% from \muW band.Comment: In Proc. of the IEEE International Conference on Communications
(ICC), Mobile and Wireless Networks Symposium, Kualalumpur, Malaysia, May
201
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