Cooperative Hybrid Research Articles

Examination and Operating Room Scheduling Including Optimization of Intrahospital Routing

Hospitalized patients typically undergo several examinations before their actual surgery. Transportation between service units is provided by trained personnel who escort patients. However, valuable resources may be underutilized if patients arrive too late for scheduled appointments, whereas on the other side, many patients have to wait for a long time before being picked up for, or after, their actual appointment. To improve those deficits, this study adopts on both resource- and client-centered perspectives. Therefore, we present an integrative combinatorial optimization model combining both scheduling- and routing-related aspects, which will be solved using a cooperative hybrid metaheuristic. Traditionally, both underlying subproblems would be solved independently, but the cooperative approach yields substantial advantages over decoupled hierarchical optimization processes.

Cooperative and Forwarding Hybrid Routing Algorithm for Network Lifetime Maximization in Wireless Sensor Network

PDF HTML阅读 XML下载 导出引用 引用提醒 一种协作和中继混合的传感网寿命最大化路由算法 DOI: 10.3724/SP.J.1001.2013.04380 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金(60872043)；国家科技重大专项(2010ZX03006-002，2011ZX03005-003) Cooperative and Forwarding Hybrid Routing Algorithm for Network Lifetime Maximization in Wireless Sensor Network Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:周期性监控、多对一数据传输是无线传感网的典型场景之一.其中存在固有的能耗不均问题，即与sink 节点距离不同的节点能耗差异大，严重缩短了网络寿命.提出了一种基于协作和中继混合传输模式的路由方法，利用协作和中继在远、近距离传输时能耗的互补性，通过调整节点采用中继模式传输的负载比例(称为中继率)，均衡节点间的能耗，延长网络寿命.定量地描述了节点能耗和中继率的关系，将网络寿命最大化建模为关于中继率矢量的高阶非线性优化问题.为了求解该问题，深入分析了寿命最大化时节点间能耗的关系，得到的结论是：若以中继模式传输单比特的能耗小于sink 一跳邻节点的协作模式能耗，则寿命最大化时所有节点能耗相等；否则，寿命最大化时节点中仅满足协作模式能耗大于中继模式的部分节点能耗相等.由此将多元非线性的网络寿命最大化问题转化为关于单变量的优化问题，求得了最优中继率.利用理论分析结果设计了分布式路由算法DORRCR.仿真结果表明，该算法能够有效延长网络寿命，显著提高全网的能耗均衡性. Abstract:Periodic monitoring and many-to-one data transmission is one of the representative scenarios in wireless sensor networks where inherent uneven energy consumption problem exists, that is nodes with different distances away from sink have different energy consumptions and it seriously reduces network lifetime. A routing algorithm is proposed based on cooperative and forwarding hybrid transmission modes, which utilizes the complementary characteristic in energy consumption of cooperative and forwarding transmission over long and short distance, and balances nodes' energy consumption through tuning the traffic ratio transmit by non-cooperative mode (referred to as relay ratio). Network lifetime maximization (NLM) is modeled as optimization of relay ratio vector, which is a high order non-linear optimization problem of multiple variables. To solve this problem, theoretical analysis is carried out on node energy consumption when network lifetime is maximized and an important conclusion is reached: if bit-energy-consumption of forwarding mode is lower than that of cooperative mode of sink's one-hop neighbor, all nodes have equal energy consumption when network lifetime is maximized; otherwise, only nodes whose bit-energy-consumption of cooperative mode is higher than that of forwarding mode have equal energy consumptions. As a result, NLM, a high order non-linear optimization problem, is simplified into an optimization about single variable. A distributed optimal relay ratio based routing algorithm (DORRCR) is designed based on the theoretical analysis. Simulation shows that, DORRCR prolongs network lifetime greatly compared with pure cooperative and non-cooperative energy balance routing protocols and evidently balances energy balance over the whole network. 参考文献 相似文献 引证文献

A Robust Evolutionary Algorithm for Large Scale Optimization

In this paper we present a new cooperative coevolution hybrid Taguchi-genetic algorithm (CCHTGA) to solve high-dimensional optimization problems with continuous variables which are typical in large scale systems. The CCHTGA employs cooperative coevolution frame to decompose the problem into several subsystems and adopts a novel decomposition technique “random grouping strategy”. Subsystem optimizer is an improved hybrid Taguchi-genetic algorithm (HTGA) which is effective, more robust and rapidly convergent. The performance of the CCHTGA compared to a state-of-the-art cooperative coevolution particle swarm algorithm (CCPSO2). The simulation results obtained from the application of this method to function optimization indicate that CCHTGA can be a competitive algorithm to achieve better and robust results.

Hybrid Cooperative Beamforming and Jamming for Physical-Layer Security of Two-Way Relay Networks

In this paper, we propose a hybrid cooperative beamforming and jamming scheme to enhance the physical-layer security of a single-antenna-equipped two-way relay network in the presence of an eavesdropper. The basic idea is that in both cooperative transmission phases, some intermediate nodes help to relay signals to the legitimate destination adopting distributed beamforming, while the remaining nodes jam the eavesdropper, simultaneously, which takes the data transmissions in both phases under protection. Two different schemes are proposed, with and without the instantaneous channel state information of the eavesdropper, respectively, and both are subjected to the more practical individual power constraint of each cooperative node. Under the general channel model, it is shown that both problems can be transformed into a semi-definite programming (SDP) problem with an additional rank-1 constraint. A current state of the art technique for handling such a problem is the semi-definite relaxation (SDR) and randomization techniques. In this paper, however, we propose a penalty function method incorporating the rank-1 constraint into the objective function. Although the so-obtained problem is not convex, we develop an efficient iterative algorithm to solve it. Each iteration is a convex SDP problem, thus it can be efficiently solved using the interior point method. When the channels are reciprocal such as in TDD mode, we show that the problems become second-order convex cone programming ones. Numerical evaluation results are provided and analyzed to show the properties and efficiency of the proposed hybrid security scheme, and also demonstrate that our optimization algorithms outperform the SDR technique.

Parameter identification for solid oxide fuel cells using cooperative barebone particle swarm optimization with hybrid learning

Solid oxide fuel cell (SOFC) has been widely recognized as one of the most promising fuel cells. The SOFC performance is highly influenced by several parameters associated with the internal multi-physicochemical processes. In this work, the optimal modeling strategy is designed to determine the parameters of SOFC using a simple and efficient barebone particle swarm optimization (BPSO) algorithm. The cooperative coevolution strategy is applied to divide the output voltage function into four subfunctions based on the interdependence among variables. To the nonlinear characteristic of SOFC model, a hybrid learning strategy is proposed for BPSO to ensure a good balance between exploration and exploitation. The experimental results illustrate the effectiveness of the proposed algorithm. The comparisons also indicate that cooperative coevolution strategy and hybrid learning improve the performance of original PSO algorithm, offering better approximation effect and stronger robustness.

Throughput and Energy Efficiency of a Cooperative Hybrid ARQ Protocol for Underwater Acoustic Sensor Networks

Due to its efficiency, reliability and better channel and resource utilization, cooperative transmission technologies have been attractive options in underwater as well as terrestrial sensor networks. Their performance can be further improved if merged with forward error correction (FEC) techniques. In this paper, we propose and analyze a retransmission protocol named Cooperative-Hybrid Automatic Repeat reQuest (C-HARQ) for underwater acoustic sensor networks, which exploits both the reliability of cooperative ARQ (CARQ) and the efficiency of incremental redundancy-hybrid ARQ (IR-HARQ) using rate-compatible punctured convolution (RCPC) codes. Extensive Monte Carlo simulations are performed to investigate the performance of the protocol, in terms of both throughput and energy efficiency. The results clearly reveal the enhancement in performance achieved by the C-HARQ protocol, which outperforms both CARQ and conventional stop and wait ARQ (S&W ARQ). Further, using computer simulations, optimum values of various network parameters are estimated so as to extract the best performance out of the C-HARQ protocol.

Hybrid Spectrum Sharing with Cooperative Secondary User Selection in Cognitive Radio Networks

In this paper, we propose a cooperative hybrid spectrum sharing protocol by jointly considering interweave (opportunistic) and underlay schemes. In the proposed protocol, secondary users can access the licensed spectrum along with the primary system. Our network scenario comprises a single primary transmitter-receiver (PTx-PRx) pair and a group of M secondary transmitter-receiver (STx-SRx) pairs within the transmission range of the primary system. Secondary transmitters are divided into two groups: active and inactive. A secondary transmitter that gets an opportunity to access the secondary spectrum is called “active”. One of the idle or inactive secondary transmitters that achieves the primary request target rate R PT will be selected as a best decode-and-forward (DF) relay (Re) to forward the primary information when the data rate of the direct link between PTx and PRx falls below R PT . We investigate the ergodic capacity and outage probability of the primary system with cooperative relaying and outage probability of the secondary system. Our theoretical and simulation results show that both the primary and secondary systems are able to achieve performance improvement in terms of outage probability. It is also shown that ergodic capacity and outage probability improve when the active secondary transmitter is located farther away from the PRx.

A Cooperative Hybrid Caching Strategy for P2P Mobile Network

Recently mobile network technologies develop quickly. To meet the increasing demand of wireless users, many multimedia proxies have been deployed over wireless networks. The caching nodes constitute a wireless caching system with an architecture of P2P and provide better service to mobile users. In this paper, we formulate the caching system to optimize the consumption of network bandwidth and guarantee the response time of mobile users. Two strategies: single greedy caching strategy and cooperative hybrid caching strategy are proposed to achieve this goal. Single greedy caching aims to reduce bandwidth consumption from the standpoint of each caching node, while cooperative hybrid caching allows sharing and coordination of multiple nodes, taking both bandwidth consumption and popularity into account. Simulation results show that cooperative hybrid caching outperforms single greedy caching in both bandwidth consumption and delay time.

Delay‐limited throughput analysis of cooperative hybrid automatic repeat request in asymmetric fading channels

This study analyses the delay-limited throughput performance of an uplink cellular relay network utilising hybrid automatic repeat request (HARQ) protocol in which one mobile station (MS) communicates with one base station (BS) with the aid of one amplify-and-forward relay station (RS). The authors’ analysis allows for a practical fading scenario where MS → RS and RS → BS channels undergo independent Rayleigh and Rician fading, respectively. Delay-limited throughput expressions for two HARQ protocols are derived, respectively, namely Repetition Time Diversity and Incremental Redundancy. Furthermore, the impact of different parameters on the achievable throughput, such as the maximum HARQ round number L, line-of-sight signal K, information rate R etc., is analysed. The authors’ analysis unveils that, for the presumed dual-hop cooperation model with the specified tolerable delay requirement and given channel condition, there exists an optimal information rate R* that achieves the maximum delay-limited throughput for the two HARQ protocols. Moreover, it is disclosed that, both HARQ protocols with the adaptive optimised information rate outperform the counterpart with the fixed information rate in low and moderate SNR regions, suggesting that an adaptive transmission scheme should be employed to achieve a better throughput performance.

Large-scale Surveillance System based on Hybrid Cooperative Multi-Camera Tracking

In this paper, we proposed an optimized real-time hybrid cooperative multi-camera tracking system for large-scale au-tomate surveillance based on embedded smart cameras including stationary cameras and moving pan/tilt/zoom (PTZ) cameras embedded with TI DSP TMS320DM6446 for intelligent visual analysis. Firstly, the overlapping areas and projection relations between adjacent cameras' field of view (FOV) is calculated. Based on the relations of FOV ob-tained and tracking information of each single camera, a homography based target handover procedure is done for long-term multi-camera tracking. After that, we fully implemented the tracking system on the embedded platform de-veloped by our group. Finally, to reduce the huge computational complexity, a novel hierarchical optimization method is proposed. Experimental results demonstrate the robustness and real-time efficiency in dynamic real-world environ-ments and the computational burden is significantly reduced by 98.84%. Our results demonstrate that our proposed sys-tem is capable of tracking targets effectively and achieve large-scale surveillance with clear detailed close-up visual features capturing and recording in dynamic real-life environments.

Three improved hybrid metaheuristic algorithms for engineering design optimization

This paper presents three hybrid metaheuristic algorithms that further improve the two hybrid differential evolution (DE) metaheuristic algorithms described in Liao [1]. The three improved algorithms are: (i) MDE′–HJ, which is a modification of MA–MDE′ in Liao [1] by replacing the random walk with direction exploitation local search with the Hooke and Jeeves (HJ) method; (ii) MDE′–IHS–HJ, which is constructed by adding the Hooke and Jeeves method to the original cooperative hybrid, i.e., MDE′–IHS; and (iii) PSO–MDE′–HJ, which is a variation of MDE′–IHS–HJ by replacing improved harmony search (IHS) with particle search optimization (PSO). A comprehensive comparative study was carried out to compare the three improved hybrids with the three algorithms presented by Liao [1] in terms of average success rate, average function evaluations taken, average elapsed CPU time, and convergence profiles. A total of 18 problems, 4 more than those used in Liao [1], were selected from different engineering domains for testing. The test results indicate that all three new hybrids can achieve higher success rate in much less CPU time. Among these three hybrids, MDE′–IHS–HJ is the best one in terms of success rate, better than the best hybrid in Liao [1] by over 15% and better than the second best, PSO–MDE′–HJ, by nearly 10%.

Hybrid ant colony optimization algorithms for mixed discrete–continuous optimization problems

This paper presents three new hybrid ant colony optimization algorithms that are extended from the ACOR developed by Socha and Dorigo for solving mixed discrete–continuous constrained optimization problems. The first two hybrids, labeled ACOR-HJ and ACOR-DE, differs in philosophy with the former integrating ACOR with the effective Hooke and Jeeves local search method and the latter a cooperative hybrid between ACOR and differentia evolution. The third hybrid, labeled ACOR-DE-HJ, is the second cooperative hybrid enhanced with the Hooke and Jeeves local search. All three algorithms incorporate a method to handle mixed discrete–continuous variables and the Deb’s parameterless penalty method for handling constraints. Fourteen problems selected from various domains were used for testing the performance of both algorithms. It was showed that all three algorithms greatly outperform the original ACOR in finding the exact or near global optima. An investigation was also carried out to determine the relative performance of applying local search with a fixed probability or varying probability.

Cooperative Hybrid ARQ in Solar Powered Wireless Sensor Networks

Energy harvesters are used in today’s Wireless Sensor Networks (WSNs) to harvest energy from the environment. Although an energy harvester can provide a supply source with a much greater lifetime than a battery, the amount of available energy for an energy harvesting system is a random variable. Furthermore, the proper management of energy harvesters has a considerable impact on reliability. It has been observed that cooperative error control mechanisms like Cooperative Automatic Repeat Request (C-ARQ) and Cooperative Hybrid ARQ (C-HARQ) can be used for improving the energy management and reliability in Energy Harvesting WSNs (EH-WSNs). Recently, the impact of C-ARC mechanism has been considered in an energy harvesting system (GAP4S), however, GAP4S is an EH-WSN powered by microwave with linear recharge rate and unbounded storage capacity. This work evaluates the effect of C-HARC using a new method of relay node selection in EH-WSNs which are powered by the solar energy and have variable recharge rates. Furthermore, a comparative study of C-ARQ and C-HARQ mechanisms, considering the impact of variations in transmission rate and packet error probability on the energy consumption, is provided. The results show that C-HARQ outperforms C-ARQ under the same conditions and the energy consumption of a relay node in C-HARQ is 50% less than the one in C-ARQ.

Performance Analysis for Superposition Modulated Cooperative Relay HARQ Networks

In this paper, a two-user superposition modulated cooperative relay hybrid automatic repeat request (HARQ) system is proposed. Two mobile station (MS) uplink communications to the base station (BS) with cooperative assistance of a relay station (RS) are considered. The RS is assumed to be able to perfectly monitor and decode the two MS-to-BS transmitted packets and assist the two MSs by immediately transmitting a cooperative superposition modulated packet that combines the two MS generated packets in the analog domain. The BS is assumed to have perfect channel statistical information and can feed back the appropriate superposition weighting factor to the RS regularly. The HARQ retransmissions, if needed, are then jointly performed by the RS for both MSs instead of separately for each MS. The superposition of the modulated packets is repeatedly retransmitted by the RS to the BS if needed. With the foregoing setting, we derive an information-theoretic achievable rate region and an approximation of the system outage probability. Based on the high SNR behaviors of the approximated system outage probability, we obtain the superposition weighting factor using a simple and efficient searching algorithm. We also analytically derive the HARQ system throughput as the performance metric for comparison. Compared with the traditional relaying HARQ system, our proposed scheme exhibits more than 30% gain in terms of system throughput, depending on the fading statistics of the RS-to-BS and MS-to-BS channels.

Hybrid modeling of counterion mass transfer in a membrane-supported biofilm reactor

This paper presents a hybrid mechanistic/statistical model for predicting counterion fluxes across an ion-exchange membrane in a membrane-supported biofilm reactor. The model was calibrated with operating data for the removal of nitrate and perchlorate from a simulated contaminated drinking water stream. Two different modeling strategies were tested: a cooperative parallel hybrid model and a competitive mixture-of-experts (MOE) structure both joining a mechanistic Donnan-dialytic transport model and a multivariate projection to latent structures (PLS) model. The MOE structure proved to be a better predictive tool since it combines the two hybrid model elements in a mediated network. The PLS model was used to identify the process variables that are responsible for the mechanistic model inaccuracy. The results showed that biocompartment physicochemical data need to be considered in the modeling of the transport of counterions across the membrane, especially in situations in which the target counterion (e.g., perchlorate or nitrate) is metabolically reduced in the biocompartment. By using this strategy, the complex biofilm contribution to the transport was accounted for, without the need of developing mechanistic models built on simplified and/or inaccurate assumptions.

Hybrid Cooperative Positioning Based on Distributed Belief Propagation

We propose a novel cooperative positioning algorithm that fuses information from satellites and terrestrial wireless systems, suitable for \acs{GPS}-challenged scenarios. The algorithm is fully distributed over an unstructured network, does not require a fusion center, does not rely on fixed terrestrial infrastructure, and is thus suitable for ad-hoc deployment. The proposed message passing algorithm, named \acf{H-SPAWN}, is described and analyzed. A novel parametric message representation is introduced, to reduce computational and communication overhead. Through simulation, we show that \ac{H-SPAWN} improves positioning availability and accuracy, and outperforms hybrid positioning algorithms based on conventional estimation techniques.

Analysis and redesign of the ‘TTC’ and ‘TTH’ schedulers

The Time-Triggered Cooperative (TTC) and TT Hybrid (TTH) schedulers have previously been described in the literature as highly predictable static schedulers with very low overheads, which are suitable for use in resource-constrained embedded software applications. Although several previous papers have considered these schedulers to a certain degree of depth, to date there has not been (i) a serious comparative investigation of the scheduler properties or (ii) the attempt to apply mainstream scheduling theory within their frameworks. As designs based around the TTC framework seem to be increasing in popularity, with operating systems based around these schedulers now commercially available, these points should be investigated; this is the focus of the current paper. The investigation reveals that although it can be said that the schedulers are predictable, their underlying operation seems to be dynamic - in the regular sense of task priorities - and employs the Earliest Activation First (EAF) priority assignment rule. In addition, with their present design the TTC/TTH scheduling overheads do not scale well, and can be excessive in comparison to alternative techniques. Motivated by these observations, the paper goes onto describe: (i) a re-design of the schedulers which allows the overheads to scale at an acceptable level, and improves the flexibility of the scheduler, (ii) the formulation and proof of an optimal tie-breaking rule for the schedulers, and (iii) the application of mainstream scheduling theory to yield a schedulability test of improved efficiency. The effectiveness of these modifications is illustrated with a small comparative study. Finally, the paper provides an overview of TTC and TTH properties in comparison to other popular scheduler architectures. These latter points should be of interest to practitioners in the field.

OFDMA 상향링크 네트워크에서 협력 하이브리드 기법의 설계 및 성능 평가

MIMO는 시스템의 크기와 비용측면 그리고 하드웨어의 복잡도 증가 등의 단점이 있다. 따라서 협력 전송 기술은 최근에 활발하게 논의 되고 있으며 또한 음영지역의 증가 문제를 해결할 수 있다. 그러나 수신측의 단일 안테나 사용으로 협력 기술은 제한적으로 이용되고 있다. 하지만 베이스스테이션에서는 간단히 다중안테나를 설치할 수 있으므로 협력전송을 통한 다이버시티와 멀티플렉싱을 적용하기가 용이하다. 높은 처리량과 신뢰성을 보장하기 위해 협력 하이브리드 순환 릴레이 다이버시티 전송 방식은 임의의 수만큼 릴레이를 사용할 수 있다. 그리고 제안된 기법은 기존의 다양한 MIMO-OFDM통신 시스템에 적용할 수 있다는 것을 볼 수 있다. The MIMO has weak points such as size and cost of systems and the complexity of hardware augment. Thus, the cooperative transmission techniques have been recently discussed briskly and it also solves problems by increase of shadowy area. However, limited cooperation scheme is utilized due to a single-antenna at the destination. The base station is simply equipped with multiple antennas. When the base station has multiple antennas, cooperative diversity and multiplexing schemes can be easily applied in the base station. To guarantee reliability with high throughput, a cooperative hybrid cyclic relay diversity transmission scheme is proposed which can use an arbitrary number of relays without rate loss and a modification of the base station. The presented results show that the proposed schemes can be effectively applied to the existing various MIMO-OFDM communication system.

Prototyping a Hybrid Cooperative and Tele-robotic Surgical System for Retinal Microsurgery

This paper presents the design of a tele-robotic microsurgical platform designed for development of cooperative and tele-operative control schemes, sensor based smart instruments, user interfaces and new surgical techniques with eye surgery as the driving application. The system is built using the distributed component-based cisst libraries and the Surgical Assistant Workstation framework. It includes a cooperatively controlled EyeRobot2, a da Vinci Master manipulator, and a remote stereo visualization system. We use constrained optimization based virtual fixture control to provide Virtual Remote-Center-of-Motion (vRCM) and haptic feedback. Such system can be used in a hybrid setup, combining local cooperative control with remote tele-operation, where an experienced surgeon can provide hand-over-hand tutoring to a novice user. In another scheme, the system can provide haptic feedback based on virtual fixtures constructed from real-time force and proximity sensor information.

Inorganic-Organic Hybrid Copolymers derived from Silsesquioxanes or Carborane Building Blocks

ABSTRACTTo explore competitive or cooperative effects novel organic-inorganic hybrid copolymers are being prepared and studied. The use of polyhedral oligomeric silsesquioxanes (POSS), a molecularly precise isotropic comonomer, is being utilized to take advantage of the inherent size scale of these particles, average diameters of 1-2 nm. The organic component selected for study in these hybrid systems are either semi-crystalline or amorphous polymers. The architectures of the hybrid copolymers range from random, to precise block copolymers, as well as telechelic and hemi-telechelic end-functionalized model compounds. The degree of POSS aggregation that occurs is found to be a function of thermal history, and processing conditions. Templating, or arresting, aggregation can be achieved using either crystalline organic polymer scaffolds in the bulk. The second inorganic comonomers for study has been constructed from icosahedral carboranes. Dicarbo-closo-decaboranes have been widely investigated for their thermal stability, chemical resistance, unique geometry, and the high cross-section for the capture of thermal neutrons. While carboranes have been widely incorporated into small molecules, metal complexes, and on a limited basis in polymer systems relatively little work exists relating their unique properties to systems with extended π-conjugation. Details of the syntheses, characterization and performance properties of both sets of hybrid systems will be discussed.