Necessary and sufficient optimality conditions for scheduling unit time jobs on identical parallel machines

In this paper we characterize optimal schedules for scheduling problems with parallel machines and unit processing times by providing necessary and sufficient conditions of optimality. We show that the optimality conditions for parallel machine scheduling are equivalent to detecting negative cycles in a specially defined graph. For a range of the objective functions, we give an insight into the underlying structure of the graph and specify the simplest types of cycles involved in the optimality conditions. Using our results we demonstrate that the optimality check can be performed by faster algorithms in comparison with existing approaches based on sufficient conditions

Food Supply and Seawater pCO2 Impact Calcification and Internal Shell Dissolution in the Blue Mussel Mytilus edulis

Progressive ocean acidification due to anthropogenic CO2 emissions will alter marine ecosytem processes. Calcifying organisms might be particularly vulnerable to these alterations in the speciation of the marine carbonate system. While previous research efforts have mainly focused on external dissolution of shells in seawater under saturated with respect to calcium carbonate, the internal shell interface might be more vulnerable to acidification. In the case of the blue mussel Mytilus edulis, high body fluid pCO2 causes low pH and low carbonate concentrations in the extrapallial fluid, which is in direct contact with the inner shell surface. In order to test whether elevated seawater pCO2 impacts calcification and inner shell surface integrity we exposed Baltic M. edulis to four different seawater pCO2 (39, 142, 240, 405 Pa) and two food algae (310–350 cells mL−1 vs. 1600–2000 cells mL−1) concentrations for a period of seven weeks during winter (5°C). We found that low food algae concentrations and high pCO2 values each significantly decreased shell length growth. Internal shell surface corrosion of nacreous ( = aragonite) layers was documented via stereomicroscopy and SEM at the two highest pCO2 treatments in the high food group, while it was found in all treatments in the low food group. Both factors, food and pCO2, significantly influenced the magnitude of inner shell surface dissolution. Our findings illustrate for the first time that integrity of inner shell surfaces is tightly coupled to the animals' energy budget under conditions of CO2 stress. It is likely that under food limited conditions, energy is allocated to more vital processes (e.g. somatic mass maintenance) instead of shell conservation. It is evident from our results that mussels exert significant biological control over the structural integrity of their inner shell surfaces

INVESTIGATION OF PUEA IN COGNITIVE RADIO NETWORKS USING ENERGY DETECTION IN DIFFERENT CHANNEL MODEL

<div>ABSTRACT</div><div><br></div><div>Primary User Emulation Attack (PUEA) is one of the major threats to the spectrum sensing in cognitive radio networks. This paper studies the PUEA using energy detection that is based on the energy of the received signal. It discusses the impact of increasing the number of attackers on the performance of secondary user. Moreover, studying how the malicious user can emulate the Primary User (PU) signal is made. This is the first analytical method to study PUEA under a different number of attackers. The detection of the PUEA increases with increasing the number of attackers and decreases when changing the channel from lognormal to Rayleigh fading.</div><div><br></div><div>KEYWORDS:</div><div><br></div><div>Cognitive Radio, Primary User Emulation Attacks (PUEA), energy detector.</div

Independent Theatre as a Political Position

We address the problem of scheduling n identical jobs on m uniform parallel machines to optimize scheduling criteria that are nondecreasing in the job completion times. It is well known that this can be formulated as a linear assignment problem, and subsequently solved in O(n3) time. We give a more concise formulation for minsum criteria, and show that general minmax criteria can be minimized in O(n2) time. We present faster algorithms, requiring only O(n+mlog m) time for minimizing makespan and total completion time, O(nlogn) time for minimizing total weighted completion time, maximum lateness, total tardiness and the weighted number of tardy jobs, and O(nlog2n) time for maximum weighted tardiness. In the case of release dates, we propose an O(nlogn) algorithm for minimizing makespan, and an O(mn2m+1) time dynamic programming algorithm for minimizing total completion time

INVESTIGATION OF PUEA IN COGNITIVE RADIO NETWORKS USING ENERGY DETECTION IN DIFFERENT CHANNEL MODEL

Primary User Emulation Attack (PUEA) is one of the major threats to the spectrum sensing in cognitive radio networks. This paper studies the PUEA using energy detection that is based on the energy of the received signal. It discusses the impact of increasing the number of attackers on the performance of secondary user. Moreover, studying how the malicious user can emulate the Primary User (PU) signal is made. This is the first analytical method to study PUEA under a different number of attackers. The detection of the PUEA increases with increasing the number of attackers and decreases when changing the channel from log normal to Rayleigh fading

Coaching Elite Kickers for Optimum Performance

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On-line Algorithms for a Single Machine Scheduling Problem

An increasingly significant branch of computer science is the study of online algorithms. In this paper, we apply the theory of on-line algorithms to job scheduling. In particular, we study the nonpreemptive single machine scheduling of independent jobs with arbitrary release dates to minimize the total completion time. We design and analyze two on-line algorithms which make scheduling decisions without knowing about jobs that will arrive in future. Keywords: job scheduling, on-line algorithm, c-competitiveness 1 Introduction Given a sequence of requests, an on-line algorithm is one that responds to each request in the order it appears in the sequence without the knowledge of any request following it in the sequence. For instance, in the bin packing problem, a list L = (a 1 ; a 2 ; : : : ; a n ) of reals in (0; 1] needs to be packed into the minimum number of unit-capacity bins. An on-line bin packing algorithm packs a i , where i starts from 1, without knowing about a i+1 ; : : : ; ..