4,694 research outputs found
Local-Search Based Heuristics for Advertisement Scheduling
In the MAXSPACE problem, given a set of ads A, one wants to place a subset A'
of A into K slots B_1, ..., B_K of size L. Each ad A_i in A has size s_i and
frequency w_i. A schedule is feasible if the total size of ads in any slot is
at most L, and each ad A_i in A' appears in exactly w_i slots. The goal is to
find a feasible schedule that maximizes the space occupied in all slots. We
introduce MAXSPACE-RDWV, a MAXSPACE generalization with release dates,
deadlines, variable frequency, and generalized profit. In MAXSPACE-RDWV each ad
A_i has a release date r_i >= 1, a deadline d_i >= r_i, a profit v_i that may
not be related with s_i and lower and upper bounds w^min_i and w^max_i for
frequency. In this problem, an ad may only appear in a slot B_j with r_i <= j
<= d_i, and the goal is to find a feasible schedule that maximizes the sum of
values of scheduled ads. This paper presents some algorithms based on
meta-heuristics GRASP, VNS, Local Search, and Tabu Search for MAXSPACE and
MAXSPACE-RDWV. We compare our proposed algorithms with Hybrid-GA proposed by
Kumar et al. (2006). We also create a version of Hybrid-GA for MAXSPACE-RDWV
and compare it with our meta-heuristics. Some meta-heuristics, such as VNS and
GRASP+VNS, have better results than Hybrid-GA for both problems. In our
heuristics, we apply a technique that alternates between maximizing and
minimizing the fullness of slots to obtain better solutions. We also applied a
data structure called BIT to the neighborhood computation in MAXSPACE-RDWV and
showed that this enabled ours algorithms to run more iterations
Unveiling User Behavior on Summit Login Nodes as a User
We observe and analyze usage of the login nodes of the leadership class
Summit supercomputer from the perspective of an ordinary user -- not a system
administrator -- by periodically sampling user activities (job queues, running
processes, etc.) for two full years (2020-2021). Our findings unveil key usage
patterns that evidence misuse of the system, including gaming the policies,
impairing I/O performance, and using login nodes as a sole computing resource.
Our analysis highlights observed patterns for the execution of complex
computations (workflows), which are key for processing large-scale
applications.Comment: International Conference on Computational Science (ICCS), 202
TEMPORAL AND SPATIAL DISTRIBUTION OF POACEAE POLLEN IN AREAS OF SOUTHERN UNITED KINGDOM, SPAIN AND PORTUGAL
Overall, longer Poaceae pollen seasons coincided with earlier pollen season start dates. Winter rainfall noticeably affects
the intensity of Poaceae pollen seasons in Mediterranean areas, but this was not as important in Worcester. Weekly data
from Worcester followed a similar pattern to that of Badajoz and Évora but at a distance of more than 1500 km and 4-5
weeks later
Toxicity of neem oil to the cassava green mite Mononychellus tanajoa (Bondar) (Acari: Tetranychidae)
O artigo não contém o resumo português.Neem (Azadirachta indica A. Juss.)-derived pesticides have been used against a wide range of agricultural pests including
tetranychid mites. Approaches combining lethal and sublethal toxicity studies of neem pesticides towards tetranychid mites
are necessary to a comprehensive evaluation of such products. Here, we evaluated the lethal and sublethal toxicity of the
neem oil Bioneem to the cassava green mite Mononychellus tanajoa (Bondar) by integrating lethal concentration (LC) with
population growth and biological parameter studies. According to Probit analyses the concentration of neem oil Bioneem
which kills 50% of the population (LC50) of M. tanajoa was 3.28 μL cm^-2, which is roughly twice the field concentration
recommended of this biopesticide to control pest mites (1.7 μL cm^-2). The growth rate of the cassava green mite steadily
decreased with dosages of neem oil. Furthermore, sublethal concentrations of the neem oil corresponding to the LC50
reduced the periods of the immature stages of M. tanajoa resulting in a shorter developmental time. Similarly, the number
of eggs per day and the number of eggs per female per day, a proxy for fecundity, were drastically reduced in M. tanajoa
females exposed to the LC50 of neem oil. Based on our comprehensive approach we conclude that the neem oil showed
lethal as well as sublethal toxicity on growth rate and biological parameters such as duration of immature stages and
fecundity of the cassava green mite M. tanajoa and it could be used as an ecological alternative for the management of this
pest
Relación entre la variación horaria de la concentración de polen de Púmtago y la meteorología
XV lnternational A.P.L.E. Symposium of Palynolog
Approximation algorithms for the MAXSPACE advertisement problem
In the MAXSPACE problem, given a set of ads A, one wants to schedule a subset
A' of A into K slots B_1, ..., B_K of size L. Each ad A_i in A has a size s_i
and a frequency w_i. A schedule is feasible if the total size of ads in any
slot is at most L, and each ad A_i in A' appears in exactly w_i slots. The goal
is to find a feasible schedule that maximizes the sum of the space occupied by
all slots. We introduce a generalization called MAXSPACE-R in which each ad A_i
also has a release date r_i >= 1, and may only appear in a slot B_j with j >=
r_i. We also introduce a generalization of MAXSPACE-R called MAXSPACE-RD in
which each ad A_i also has a deadline d_i <= K, and may only appear in a slot
B_j with r_i <= j <= d_i. These parameters model situations where a subset of
ads corresponds to a commercial campaign with an announcement date that may
expire after some defined period. We present a 1/9-approximation algorithm for
MAXSPACE-R and a polynomial-time approximation scheme for MAXSPACE-RD when K is
bounded by a constant. This is the best factor one can expect, since MAXSPACE
is NP-hard, even if K = 2
The Analyticity of a Generalized Ruelle's Operator
In this work we propose a generalization of the concept of Ruelle operator
for one dimensional lattices used in thermodynamic formalism and ergodic
optimization, which we call generalized Ruelle operator, that generalizes both
the Ruelle operator proposed in [BCLMS] and the Perron Frobenius operator
defined in [Bowen]. We suppose the alphabet is given by a compact metric space,
and consider a general a-priori measure to define the operator. We also
consider the case where the set of symbols that can follow a given symbol of
the alphabet depends on such symbol, which is an extension of the original
concept of transition matrices from the theory of subshifts of finite type. We
prove the analyticity of the Ruelle operator and present some examples
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