Next generation cellular networks will provide users better experiences with smaller cells, which results in high dynamics and interferences. Conventional approaches for inter-cell interference coordination (ICIC) are...
详细信息
ISBN:
(纸本)9781467309202
Next generation cellular networks will provide users better experiences with smaller cells, which results in high dynamics and interferences. Conventional approaches for inter-cell interference coordination (ICIC) are based on fixed frequency reuse, which wastes frequency resources. As a result, the benefit brought by ICIC is suspect in practical networks. In this paper, we tackle this problem by optimizing fractional frequency reuse (FFR) and adapting to dynamic traffic maps. We formulate this problem as a multi-KPIs (Key Performance Indicators) optimization problem and propose a traffic-based dynamic spectrum management (DSM) algorithm to reduce the call drop and block ratio (CDBR), and improve the network throughput as well. Simulation results show that the proposed scheme greatly outperforms the traditional ones.
Since multi-objective flow shop scheduling problem (MFSP) plays a key role in practical scheduling, there has been an increasing interest in MFSP according to the literature. However, there still have been wide gaps b...
详细信息
Since multi-objective flow shop scheduling problem (MFSP) plays a key role in practical scheduling, there has been an increasing interest in MFSP according to the literature. However, there still have been wide gaps between theories and practical applications, and the review research of multi-objectiveoptimization algorithms in MFSP (objectives > 2) field is relatively scarce. In view of this, this paper provides a comprehensive review of both former and the state-of-the-art approaches on MFSP. Firstly, we introduce a broad description and the complexity of MFSP. Secondly, a taxonomy of multi-objectiveoptimizations and an analysis of the publications on MFSP are presented. It is noteworthy that heuristic and meta-heuristic methods and hybrid procedures are proven much more useful than other methods in large and complex situations. Finally, future research trends and challenges in this field are proposed and analyzed. Our survey shows that algorithms developed for MFSP continues to attract significant research interest from both theoretical and practical perspectives.
This article presents a multi-objective formulation for determining the best location and size of distributed generation. This multi-objective formulation includes reliability of service, system operational efficiency...
详细信息
This article presents a multi-objective formulation for determining the best location and size of distributed generation. This multi-objective formulation includes reliability of service, system operational efficiency, cost of purchased energy, power quality, and system security as objective functions that are the primary concern of system planners. These objectives contradict each other and have trade-off relations. Conventional approaches for optimizing a single objective yield an uncompromised solution for such multi-objective problems. The multi-objective formulation is solved using an interactive trade-off algorithm to obtain compromised or most satisfactory non-inferior solutions. The system planner has a choice to include his/her preference on each objective through interactive steps. The practical situations, such as voltage rise phenomenon and voltage dependency of loads, are addressed, incorporating certain voltage constraints and appropriate load models. The test system is an existing Indian rural distribution network.
We present two new approaches to address the optimization problem associated with engine calibration. In this area, the tuning parameters are traditionally determined in a local way, i.e., at each engine operating poi...
详细信息
We present two new approaches to address the optimization problem associated with engine calibration. In this area, the tuning parameters are traditionally determined in a local way, i.e., at each engine operating point, via a single-objective minimization problem. To overcome these restrictions, the first method we propose is able to cope with several objective functions simultaneously in the local formulation. The second method we put forward relies on a global formulation, which allows the whole driving cycle to be taken into account while remaining single-objective. At the practical level, the two methods are implemented by combining various existing techniques such as the LoLiMoT (Local Linear Model Tree) parameterization and the MO-CMA-ES (multi-objective Covariance Matrix Adaptation Evolution Strategy) algorithm. A better compromise appears to be achieved on real case applications.
Purpose - The goal of this study is to carry out multi-objectiveoptimization by considering minimization of surface roughness (Ra) and build time (T) in selective laser sintering (SLS) process, which are functions of...
详细信息
Purpose - The goal of this study is to carry out multi-objectiveoptimization by considering minimization of surface roughness (Ra) and build time (T) in selective laser sintering (SLS) process, which are functions of "build orientation". Evolutionary algorithms are applied for this purpose. The performance comparison of the optimizers is done based on statistical measures. In order to find truly optimal solutions, local search is proposed. An important task of decision making, i.e. the selection of one solution in the presence of multiple trade-off solutions, is also addressed. Analysis of optimal solutions is done to gain insight into the problem behavior. Design/methodology/approach - The minimization of Ra and T is done using two popular optimizers - multi-objective genetic algorithm (non-dominated sorting genetic algorithm (NSGA-II)) and multi-objective particle swarm optimizers (MOPSO). Standard measures from evolutionary computation - "hypervolume measure" and "attainment surface approximator" have been borrowed to compare the optimizers. Decision-making schemes are proposed in this paper based on decision theory. Findings - The objects are categorized into groups, which bear similarity in optimal solutions. NSGA-II outperforms MOPSO. The similarity of spread and convergence patterns of NSGA-II and MOPSO ensures that obtained solutions are (or are close to) Pareto-optimal set. This is validated by local search. Based on the analysis of obtained solutions, general trends for optimal orientations (depending on the geometrical features) are found. Research limitations/implications - A novel and systematic way to address multi-objectiveoptimization decision-making post-optimal analysis is shown. Simulations utilize experimentally derived models for roughness and build time. A further step could be the experimental verification of findings provided in this study. practical implications - This study provides a thorough methodology to find optimal build orientation
In recent years, one of the most significant developments in both the theory and practice of communication and networking has been the closer coupling between the design of physical-layer functionalities such as codin...
详细信息
In recent years, one of the most significant developments in both the theory and practice of communication and networking has been the closer coupling between the design of physical-layer functionalities such as coding and modulation, and the design of higher-layer functionalities such as contention resolution and scheduling. This closer coupling is characteristic of the cross-layer paradigm. It is the objective of the present survey to spell out some of the basic challenges, key communication settings, and crucial results, relevant to cross-layer analysis and design for wireless systems. This work focuses primarily on communication settings relevant to wireless cellular communications, where cross-layer design principles have arguably had the greatest impact on practical systems. In order to explore the fundamental performance limits of wireless systems operating under the cross-layer paradigm, the survey shows how information theory and network theory can be leveraged to study issues such as channel modeling, coding, source burstiness, throughput, delay, multi-user interference, multi-path fading, and energy constraints in a more coherent overall analytical and design framework. The survey first examines multiaccess communication channels, the simplest example of a network setting where multiple users share a communication medium. It reviews some of the pioneering work in extending information theory to incorporate source burstiness and queueing. It then examines cross-layer design approaches for multiaccess (uplink) fading channels in wireless communications. The key concepts of stability region, throughput optimality, and delay optimality are introduced. Optimal algorithms which maximize throughput and minimize delay for multiaccess fading channels with random arrivals and queueing are characterized. Next, the survey focuses on a similar setting for communication over broadcast (downlink) fading channels, and introduce relevant results. Finally, it examines the
In this paper, we propose an integrated model to incorporate inventory control decisions-such as economic order quantity, safety stock and inventory replenishment decisions-into typical facility location models, which...
详细信息
In this paper, we propose an integrated model to incorporate inventory control decisions-such as economic order quantity, safety stock and inventory replenishment decisions-into typical facility location models, which are used to solve the distribution network design problem. A simultaneous model is developed considering a stochastic demand, modeling also the risk poling phenomenon. multi-objective decision analysis is adopted to allow use of a performance measurement system that includes cost, customer service levels (fill rates), and flexibility (responsive level). This measurement system provides more comprehensive measurement of supply chain system performance than do traditional, single measure approaches. A multi-objective location-inventory model which permits a comprehensive trade-off evaluation for multi-objectiveoptimization is initially presented. More specifically, a multiobjective evolutionary algorithm is developed to determine the optimal facility location portfolio and inventory control parameters in order to reach best compromise of these conflicting criteria. An experimental study using practical data was then illustrated for the possibility of the proposed approach. Computational results have presented promising solutions in solving a practical-size problem with 50 buyers and 15 potential DCs and proved to be an innovative and efficient approach for so called difficult-to-solve problems.
With the increasing complexity and dynamism in todays product design and manufacturing, more optimal, robust and practicalapproaches and systems are needed to support product design and manufacturing activities. Mult...
详细信息
ISBN:
(数字)9780857296528
ISBN:
(纸本)0857296175;9780857296177
With the increasing complexity and dynamism in todays product design and manufacturing, more optimal, robust and practicalapproaches and systems are needed to support product design and manufacturing activities. multi-objective Evolutionary Optimisation for Product Design and Manufacturing presents a focused collection of quality chapters on state-of-the-art research efforts in multi-objective evolutionary optimisation, as well as their practical applications to integrated product design and manufacturing. multi-objective Evolutionary Optimisation for Product Design and Manufacturing consists of two major sections. The first presents a broad-based review of the key areas of research in multi-objective evolutionary optimisation. The second gives in-depth treatments of selected methodologies and systems in intelligent design and integrated manufacturing. Recent developments and innovations in multi-objective evolutionary optimisation make multi-objective Evolutionary Optimisation for Product Design and Manufacturing a useful text for a broad readership, from academic researchers to practicing engineers.
In translucent optical networks, connections bypass most intermediate nodes transparently. However, their signal quality is affected by the traveled distance and/or the bypass operations. Hence, they might require opt...
详细信息
The goal of optimization in vehicle design is often blurred by the myriads of requirements belonging to attributes that may not be quite related. If solutions are sought by optimizing attribute performance-related obj...
详细信息
暂无评论