FREQUENCY ASSIGNMENT

Frequency allocation problem is considered an NP problem which requires a large search space to find the optimal solution. This paper presents a hybrid algorithm between the Hopfield neural network and the tabu search techniques algorithm to allocate frequencies in the cells of cellular network. The cellular telephone system is composed of small regions called cells, it's depends on the principles of frequencies reuse due to the limited number of frequencies. As a result to this reuse the problem of frequency allocation is a raised. Simply it can be defined as the allocation of different frequencies to each cell and it's neighbouring. In this hybridization the principles of short term memory and candidate list in tabu search are embedded in Hopfield neural network to control the operation of neuron selection.

This paper focuses on establishing a communications path among an ordered sequence of moving nodes, representing vehicles. A channel is used to send information from one node to the next in the sequence on a wireless link. The set of available channels may differ from one node to the next node. Each of the available channels at a node can be used for receiving information from its predecessor node in the sequence or for transmitting information to its successor node in the sequence. However, the same channel cannot be used at a node for both receiving and transmitting information. We present algorithms that determine an optimal sequence of channels that establishes a communications path from the first node to the farthest node possible. We present a depth-first search algorithm that uses a "look-ahead" channel selection rule in order to decrease backtracking. We also present an algorithm that requires only a single pass through the sequence of nodes by identifying optimal channel assignments in subsequences of nodes without a need for backtracking. The latter algorithm requires computational effort that is proportional to the number of nodes in the ordered sequence of nodes.

This paper focuses on establishing a communications path among an ordered sequence of moving nodes, representing vehicles. A channel is used to send information from one node to the next in the sequence on a wireless link. The set of available channels may differ from one node to the next node. Each of the available channels at a node can be used for receiving information from its predecessor node in the sequence or for transmitting information to its successor node in the sequence. However, the same channel cannot be used at a node for both receiving and transmitting information. We present algorithms that determine an optimal sequence of channels that establishes a communications path from the first node to the farthest node possible. We present a depth-first search algorithm that uses a “look-ahead” channel selection rule in order to decrease backtracking. We also present an algorithm that requires only a single pass through the sequence of nodes by identifying optimal channel as...

This paper focuses on establishing a communications path among an ordered sequence of moving nodes, representing vehicles. A channel is used to send information from one node to the next in the sequence on a wireless link. The set of available channels may differ from one node to the next node. Each of the available channels at a node can be used for receiving information from its predecessor node in the sequence or for transmitting information to its successor node in the sequence. However, the same channel cannot be used at a node for both receiving and transmitting information. We present algorithms that determine an optimal sequence of channels that establishes a communications path from the first node to the farthest node possible. We present a depth-first search algorithm that uses a "look-ahead" channel selection rule in order to decrease backtracking. We also present an algorithm that requires only a single pass through the sequence of nodes by identifying optimal channel assignments in subsequences of nodes without a need for backtracking. The latter algorithm requires computational effort that is proportional to the number of nodes in the ordered sequence of nodes.

Frequency planning is a very important task for current GSM operators. In this work we present a new mathematical formulation of the problem in which the frequency plans are evaluated by using accurate interference information coming from a real GSM network. We have developed an ant colony optimization (ACO) algorithm to tackle this problem. After accurately tuning this algorithm, it has been compared against a (1,10) Evolutionary Algorithm (EA). The results show that the ACO clearly outperforms the EA when using different time limits as stopping condition for a rather extensive comparison.

Automatic Cell Planning (ACP) is an optimization problem from the mobile telecommunication domain that addresses finding the location of the network antennae as well as their parameter settings in order to satisfy several cellular operator requirements. Due to its NP-hard complexity, evolutionary techniques have become popular to solve ACP instances. This paper presents a survey of evolutionary algorithms (EAs) engineered for addressing ACP problems, analyzing both the features of the considered ACP problem and the main aspects of the EAs used to solve them. The survey provides an up-to-date overview that is not limited to any particular kind of evolutionary approach, and comprises advanced algorithmic enhancements like hybridization and parallelization. The paper ends by addressing some important issues and open questions that can be the subject of future research.

Frequency assignment is a well-known problem in Operations Research for which different mathematical models exist depending on the application specific conditions. However, most of these models are far from considering actual technologies currently deployed in GSM networks (e.g. frequency hopping). These technologies allow the network capacity to be actually increased to some extent by avoiding the interferences provoked by channel reuse due to the limited available radio spectrum, thus improving the Quality of Service (QoS) for subscribers and an income for the operators as well. Therefore, the automatic generation of frequency plans in real GSM networks is of great importance for present GSM operators. This is known as the Automatic Frequency Planning (AFP) problem. In this paper, we focus on solving this problem for a realistic-sized, real-world GSM network by using Evolutionary Algorithms (EAs). To be precise, we have developed a (1, λ) EA for which very specialized operators have been proposed and analyzed. Results show that this algorithmic approach is able to compute accurate frequency plans for real-world instances. This work has been partially funded by the Ministry of Science and Technology and FEDER under contract TIN2005-08818-C04-01 (the OPLINK project).

Nowadays, mobile communications are experiencing a strong growth, being more and more indispensable. One of the key issues in the design of mobile networks is the Frequency Assignment Problem (FAP). This problem is crucial at present and will remain important in the foreseeable future. Real world instances of FAP typically involve very large networks, which can only be handled by heuristic methods. In the present work, we are interested in optimizing frequency assignments for problems described in a mathematical formalism that incorporates actual interference information, measured directly on the field, as is done in current GSM networks. To achieve this goal, a range of metaheuristics have been designed, adapted, and rigourously compared on two actual GSM networks modeled according to the latter formalism. In order to generate quickly and reliably high quality solutions, all metaheuristics combine their global search capabilities with a local-search method specially tailored for th...

In this article we present Ethane, a parallel heterogeneous metaheuristic model specifically designed for its execution on heterogeneous hardware environments. With Ethane we propose a hybrid parallel search algorithm inspired in the structure of the chemical compound of the same name, implementing a heterogeneous island model based in the structure of the chemical bonds of the ethane compound. Here we also shape a schema for describing a complete family of parallel heterogeneous metaheuristics inspired by the structure of hydrocarbons in nature, Hyd-roCM (HydroCarbon inspired Metaheuristics), establishing a resemblance between atoms and computers, and between chemical bonds and communication links. Our goal is to gracefully match computers of different computing power to algorithms of different behavior (genetic algorithm and simulated annealing in this study), all them collaborating to solve the same problem. In addition to the nice natural metaphor we will show that Ethane, though simple, can solve search problems in a faster and more robust way than well-known panmictic and distributed algorithms very popular in the literature, as well as can achieve a better exploration/exploitation balance during the search process.

There is an unmet need for treatment options for generalized myasthenia gravis (gMG) that are effective, targeted, well tolerated, and can be used in a broad population of patients. We aimed to assess the efficacy and safety of efgartigimod (ARGX-113), a human IgG1 antibody Fc fragment engineered to reduce pathogenic IgG autoantibody levels, in patients with gMG Methods ADAPT (ClinicalTrials.gov: NCT03669588) was a randomized, double-blind, placebocontrolled, phase 3 trial of efgartigimod in gMG conducted at 56 neuromuscular academic and community centers in 15 countries. Patients with gMG were eligible to participate in the study, regardless of anti-acetylcholine receptor antibody (AChR-Ab) status, if they met the following criteria: Myasthenia Gravis Activities of Daily Living (MG-ADL) score ≥5 (more than 50% non-ocular), and on a stable dose of ≥1 treatment for gMG (acetylcholinesterase inhibitor, steroid and/or non-steroidal immunosuppressant treatment). Patients were randomized by Interactive Response Technology 1:1 to efgartigimod (10 mg/kg) or matching placebo administered as cycles of 4 weekly intravenous infusions repeated as needed, depending on clinical response. Patients, investigators, and clinical site staff were all unaware of treatment allocation. The primary endpoint was percentage of AChR-Ab+ patients who were MG-ADL responders (≥2-point MG-ADL improvement sustained for ≥4 weeks in the first treatment cycle [C1]). The primary analysis was completed on the AChR-Ab+ modified intent-to-treat population and the safety analysis included all randomized patients who received at least one dose of efgartigimod or placebo. Between September 5, 2018 and November 26, 2019, 167 patients were randomized and treated. The majority were AChR-Ab+ (n=129, 77%). Most of AChR-Ab+ efgartigimod-treated patients were MG-ADL responders (n=44/65, 67⸱7%) in C1 compared to placebo (n=19/64, 29⸱7%), with an odds ratio of 4.95 (95% CI 2.21 to 11.53, p<0.0001). Similar results were seen in other outcomes measures, successive cycles, and the overall population. A lower percentage of patients treated with efgartigimod (n=65/85, 77⸱4%) experienced treatment emergent adverse events than placebo treated (n=70/83, 84⸱3%). The majority of these events were mild or moderate in severity. Three patients in each treatment arm discontinued treatment during the study (3.6%). Efgartigimod reduced total IgG and AChR-Abs and was well tolerated overall. Efgartigimod was well tolerated and efficacious in patients with gMG. Improvements in symptoms correlated with IgG and AChR-Ab reduction, demonstrating the utility of selective IgG reduction through FcRn blockade in gMG. The individualized dosing based on clinical response was a unique feature of ADAPT, and translation to clinical practice with longer term safety and efficacy data will be further informed by the Open Label Extension.

The assignment of a subset of natural frequencies to vibrating systems can be conveniently achieved by means of suitable structural modifications. It has been observed that such an approach usually leads to the undesired change of the unassigned natural frequencies, which is a phenomenon known as frequency spill-over. Such an issue has been dealt with in the literature only in simple specific cases. In this paper, a new and general method is proposed that aims to assign a subset of natural frequencies with low spill-over. The optimal structural modifications are determined through a three-step procedure that considers both the prescribed eigenvalues and the feasibility constraints, assuring that the obtained solution is physically realizable. The proposed method is therefore applicable to very general vibrating systems, such as those obtained through the finite element method. The numerical difficulties that may occur as a result of employing the method are also carefully addressed. Finally, the capabilities of the method are validated in three test-cases in which both lumped and distributed parameters are modified to obtain the desired eigenvalues.

In this paper, we investigate the use of stochastic variable and value ordering heuristics for solving job shop scheduling problems with non-relaxable deadlines and complex metric constraints. Previous research in constraint satisfaction scheduling has developed highly effective, deterministic heuristics for this class of problems based on simple measures of temporal sequencing exibility. H o wever, they are not infallible, and the possibility of search failure raises the issue of how t o most productively enlarge the search. Backtracking is one alternative, but such systematicity generally implies high computational cost. We instead design an iterative sampling procedure, based on the intuition that it is more productive to deviate from heuristic advice in cases where the heuristic is less informed, and likewise better to follow the heuristic in cases where it is more knowledgeable. We specify stochastic counterparts to previously developed search heuristics, which are parameterized to calibrate degree of randomness to level of discriminatory power. Experimental results on job shop scheduling CSPs of increasing size demonstrate comparative advantage over chronological backtracking. Comparison is also made to another, recently proposed iterative sampling technique called heuristic-biased stochastic sampling HBSS. Whereas HBSS assumes a statically speci ed heuristic bias that is utilized at every application of the heuristic, our approach de nes bias dynamically according to how well the heuristic discriminates alternatives.

Modeling fluorescent emission from monomeric formaldehyde (H2CO) forms an integral part of our overall comprehensive program of measuring the volatile composition of comets through high-resolution (RP ~ 25,000) infrared spectroscopy using CSHELL at the IRTF and NIRSPEC at Keck II. The H2CO spectra contain lines from both the nu1 (symmetric CH2 stretch) and nu5 (asymmetric CH2 stretch) bands near 3.6 microns. We have acquired high-quality spectra of twelve Oort cloud comets, and at least six of these show clear emission from H2CO. We also detected H2CO with NIRSPEC in one Jupiter Family comet, 9P/Tempel 1, during Deep Impact observations. Our H2CO model, originally developed to interpret low-resolution spectra of comets Halley and Wilson (Reuter et al. 1989 Ap J 341:1045), predicts individual line intensities (g-factors) as a function of rotational temperature for approximately 1300 lines having energies up to approximately 400 cm^-1 above the ground state. Recently, it was validated...

In this poster, we will report progress on our near-IR sensitive searches for HDO (simultaneously with H2O or its proxy OH prompt emission) and CH3D (simultaneously with CH4) in order to constrain the D/H ratio in cometary water and methane.

We report observations of hydrogen cyanide (HCN) in comets 8P/Tuttle (hereafter 8P) and C/2007 W1 (Boattini) (hereafter C/2007 W1), performed using the CRyogenic InfraREd Spectrometer (CRIRES) at VLT. Gas production rates, mixing ratios and rotational temperatures have been retrieved using a new developed model that describe the ν 1 transition for this molecule.

For many years we have been developing the ability, through high-resolution spectroscopy targeting 1&#39;0vibrational emission in the ~ 3 5 j.lIn region, to quantify a suite of (10) parent volatiles in C0111ets using quantum mechanical fluorescence models. Our efforts are ongoing and our latest includes methanol (CH,0E). This is unique among traditionally targeted species in having lacked sufficiently robust models for its symmetric (V3 band) and asymmetric (\&#39;2 and V9 bands) C~H} stretching modes, required to provide accurate predicted intensities for individual spectral lines and hence rotational temperatures and production rates. This has provided the driver for undertaking a detailed empirical study of line intensities, and has led to substantial progress regarding our ability to interpret CH}OH in comets. The present study concentrates on the spectral region from 2970 3010 em&quot; (3.367··3.322 [tm), which is dominated by emission in the V7 band of C2H6 and the V2 band of ...