Coordination Procedures Research Articles

Coordination of Overcurrent, Directional and Differential Relays for the Protection of Microgrid System

Microgrid implementation draws new challenges especially in the coordination of protective devices that are not likely to appear in a traditional distribution network. Variation of fault current levels, bi-directional fault current and changing of microgrid operation modes make protection of the microgrids more difficult. In this work, a systematic procedure for coordination of different protection schemes is presented to secure the operation of a microgrid system. The procedure initially starts with coordination of overcurrent (OC) relays and followed by directional overcurrent (DOC) relays in the system. If the coordination of these two types of relays is unsatisfactory, then differential (DIF) relays are used to replace the OC relay in the faulty section. The proposed method takes into account device selectivity, sensitivity and proper protection function simultaneously. Simulation results show that the proposed coordination method safely protect a microgrid system during both grid-connected and islanded operation modes.

Norwegian–Russian cooperation on oil-spill response in the Barents Sea

Abstract The risks of oil pollution in the Barents Sea have grown substantially in recent years, triggered by ongoing and projected petroleum developments and increased oil transportation. This study examines the bilateral oil-spill response (OSR) regime established by Norway and Russia to provide mutual assistance in combating accidents caused by oil pollution. The article examines the structure and functioning of the regime, discussing its effectiveness analytically in terms of regime outputs, outcomes, and impacts, and the interplay between the political and profession-based aspects of the regime. This Norwegian-Russian OSR cooperation in the Barents Sea has developed into an effective bilateral regime. The general framework for cooperation, the roles and functions of the cooperating parties, and the operative coordination procedures in an emergency situation have been established through a set of formal institutional procedures. These procedures have been followed up by the parties and practiced regularly through bilateral and multilateral training exercises. Although the regime has not had to be activated, the results of the exercises and interview data indicate mutual satisfaction with the practical aspects of the cooperation and shared confidence in successful joint OSR operation. This article further explains the evolution of this effectiveness through analysis of the political and profession-based constituents of the regime. The limited political dynamic of the regime has ensured stability as well as facilitating the development of professional relations between representatives of the agencies dealing with operational issues. Therefore, the effectiveness of the Norwegian–Russian OSR regime has been a function of both political stability and professional-level achievements contingent on developments in the political processes.

Reliability-Based Multidisciplinary Design Optimization Using Probabilistic Gradient-Based Transformation Method

Recently, solving the complex design optimization problems with design uncertainties has become an important but very challenging task in the communities of reliability-based design optimization (RBDO) and multidisciplinary design optimization (MDO). The MDO algorithms decompose the complex design problem into the hierarchical or nonhierarchical optimization structure and distribute the workloads to each discipline (or subproblem) in the decomposed structure. The coordination of the local responses is crucial for the success of finding the optimal design point. The problem complexity increases dramatically when the existence of the design uncertainties is not negligible. The RBDO algorithms perform the reliability analyses to evaluate the probabilities that the random variables violate the constraints. However, the required reliability analyses build up the degree of complexity. In this paper, the gradient-based transformation method (GTM) is utilized to reduce the complexity of the MDO problems by transforming the design space to multiple single-variate monotonic coordinates along the directions of the constraint gradients. The subsystem responses are found using the monotonicity principles (MP) and then coordinated for the new design points based on two general principles. To consider the design uncertainties, the probabilistic gradient-based transformation method (PGTM) is proposed to adapt the first-order probabilistic constraints from three different RBDO algorithms, including the chance constrained programming (CCP), reliability index approach (RIA), and performance measure approach (PMA), to the framework of the GTM. PGTM is efficient because only the sensitivity analyses and the reliability analyses require function evaluations (FE). The optimization processes of monotonicity analyses and the coordination procedures are free of function evaluations. Several mathematical and engineering examples show the PGTM is capable of finding the optimal solutions with desirable reliability levels.

The G-20 framework for strong, sustainable, and balanced growth: glass half empty or half full?

The G-20 Framework for Strong, Sustainable and Balanced Growth was launched by the G-20 leaders in 2009 to strengthen coordination of national economic policies as the world emerged from the 2008–9 financial crisis. Building on earlier attempts at international economic policy coordination, the Framework has made significant advances in the detailed institutional procedures for policy coordination, including information sharing, analytical tasking, and the development of structured policy discussions to address medium-term issues. Some politically difficult challenges have been overcome using varied techniques, including enabling the system of collaboration to evolve incrementally over time. However, further progress is needed if the Framework is to deliver on the remit set by leaders.

Numerical and experimental demonstration of a coordinate transformation‐based azimuthal directive emission

AbstractThis article deals with the modeling, practical implementation, and characterization of an azimuthal directive antenna around 10 GHz. The design of the antenna is based on transformation optics concept by transforming the radiation of a plane source into an azimuthal radiation. This coordinate transformation procedure is achieved by modifying the electromagnetic properties of the space around the plane source. Metamaterials presenting electric and magnetic resonances are used to produce the effective material parameters necessary for the transformation. S11 parameter and direct far‐field measurements are performed on a fabricated prototype to experimentally demonstrate the narrow beam profile and the beam deflection. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2536–2540, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27122

A novel gray image representation using overlapping rectangular NAM and extended shading approach

In this paper, inspired by the idea of overlapping rectangular region coding of binary images, we extend the SDS design, which is based on overlapping representation from binary images to gray images based on the non-symmetry and anti-packing model (NAM). A novel gray image representation is proposed by using the overlapping rectangular NAM (RNAM) and the extended Gouraud shading approach, which is called ORNAM representation. Also, we present an ORNAM representation algorithm of gray images. The encoding and the decoding of the proposed algorithm can be performed in O(n logn) time and O(n) time, respectively, where n denotes the number of pixels in a gray image. The wrong decoding problem of the hybrid matrix R for the overlapping RNAM representation of gray images is solved by using the horizontal, vertical, and isolated matrices, i.e., H, V and I, respectively, which are used to identify the vertex types. Also, we put forward four criteria of anti-packing homogeneous blocks. In addition, by redefining a codeword set for the three vertices symbols, we also propose a new coordinate data compression procedure for coding the coordinates of all non-zone elements in the three matrices H, V and I. By taking some idiomatic standard gray images in the field of image processing as typical test objects, and by comparing our proposed ORNAM representation with the conventional S-Tree Coding (STC) representation, the experimental results in this paper show that the former has higher compression ratio and less number of homogeneous blocks than the latter whereas maintaining a satisfactory image quality, and therefore it is a better method to represent gray images.

An Optimal Procedure for Sample Coordination Using Multiple Objective Functions and Nearest Proportional to IPPS Size Sampling Designs

The sample coordination problem involves maximization or minimization of overlap of sampling units in different/repeated surveys. Several optimal techniques using transportation theory, controlled rounding, and controlled selection have been suggested in literature to solve the sample coordination problem. In this article, using the multiple objective programming, we propose a method for sample coordination which facilitates variance estimation using the Horvitz–Thompson estimator. The proposed procedure can be applied to any two-sample surveys having identical universe and stratification. Some examples are discussed to demonstrate the utility of the proposed procedure.

Resource management issues for multi-carrier relay-enhanced systems

Relaying is one of the enabling techniques for next generation systems. Factors deciding on performance of relay-enhanced systems are the resource allocation and coordination. The capacity of the wireless relay backhaul link is typically the bottleneck of transmissions conveyed through the relay node. It can be to some extent improved by allocating dedicated resources; however, typically this is done at the expense of the performance of users served directly from the base station. To achieve optimum overall performance, resource assignment to relays and users has to be done carefully. This article addresses the problem of resource allocation with relays operated in multi-carrier scenarios. Guidelines for optimization of the resource allocation under the resource fair policy are given with different relay configurations, including time, frequency, and hybrid resource partitioning schemes. Finally, advanced resource coordination procedures are presented. Multi-carrier interference coordination is proposed for improving the quality of radio links, and carrier load balancing for improving the efficiency of resource utilization.

Air Transport and Logistics in Pandemic Outbreak of Influenza A (H1N1) virus

In April 2009, the WHO, (World Health Organization) evaluated the available data on the swine influenza A (H1N1), confirmed the outbreak and declared decision on raising the pandemic phase from five to six. IATA, (International Air Transport Association) invited the airlines to support WHO’s reference laboratories around the world in handling specimens should the outbreak expand further. The specimens shall be transported according to the regulations stipulated for acceptance and transportation of dangerous goods by air. The paper analyses the current infrastructural situation at the airports in Croatia, predispositions related to the trained staff and coordination procedures with the relevant institutions. The implementation of activities complying with the international regulations are suggested in order to conduct measures fighting the pandemic in Croatia. KEY WORDS: pandemic outbreak, regulation, recommendation, specimen, responsibilities, transportation and logistic for biological substances

Kinematic Analysis of Broiler, Layer, and Turkey Stifles

The purpose of this study was to describe the movement of the broiler, layer, and turkey stifle as the joint traveled from a position of a sitting bird to a standing bird. This movement was described using the kinematic parameters of flexion, rotation, adduction/abduction as defined by the joint coordinate system procedure. The joint movement was simulated by placing cadaver limbs in an Oxford-Rig device. Results indicate that the relationship of flexion to rotation rate was linear for the broilers, layers, and turkeys where the average rotational rate was 1.2 per degree of flexion, 0.61 per degree of flexion and 0.46 per degree of flexion, respectively. This relationship for the broilers was significantly different than the relationships for both the turkey and layers, thereby suggesting that the kinematics of the broiler stifle differs from the kinematics of the layers and turkeys.

POINT-POINT FIXED WIRELESS AND BROADCASTING SERVICES COEXISTENCE WITH IMT-ADVANCED SYSTEM

Spectrum sharing analysis is remarkably important in investigating the possibility for coexistence between IMT-Advanced system and existing wireless services when operating in the same or adjacent frequency channel. The frequency band, 470{862MHz, is currently allocating to TV broadcasting services (TVBS) and sub- bands within it are also allocated to flxed wireless access (FWA) service. Recently, international telecommunication union-radio (ITU- R) sector has allocated sub-bands within 470{862MHz for IMT- Advanced systems. This concurrent operation causes destructive interference that in∞uences the coexisting feasibility between IMT- Advanced and these existing services, FWA and broadcasting. This paper addresses a timely and topical problem dealing with spectrum sharing and coexistence between IMT-Advanced systems and both FWA and TVBS within 790{862MHz. Co-channel and adjacent channel with an overlapping band and with or without guard band are intersystem interference scenarios investigated. The deterministic analysis is carried out by spectral emission mask (SEM) technique as well as interference to noise ratio graph. Various signiflcant factors such as channel width, propagation path lengths, environments losses, and additional losses due to antenna discrimination which in∞uence the feasibility of coexistence are evaluated. Feasible coexistence coordination procedures in terms of carrier frequency ofiset, separation

A cyclic representation of discrete coordination procedures

We show that any discrete opinion pooling procedure with positive weights can be asymptotically approximated by DeGroot's procedure whose communication digraph is a Hamiltonian cycle with loops. In this cycle, the weight of each arc (which is not a loop) is inversely proportional to the influence of the agent the arc leads to.

Coordination between mid-term maintenance outage decisions and short-term security-constrained scheduling in smart distribution systems

Distribution systems are the first volunteers experiencing the benefits of smart grids. The smart grid concept impacts the internal legislation and standards in grid-connected and isolated distribution systems. Demand side management, the main feature of smart grids, acquires clear meaning in low voltage distribution systems. In these networks, various coordination procedures are required between domestic, commercial and industrial consumers, producers and the system operator. Obviously, the technical basis for bidirectional communication is the prerequisite of developing such a coordination procedure. The main coordination is required when the operator tries to dispatch the producers according to their own preferences without neglecting its inherent responsibility. Maintenance decisions are first determined by generating companies, and then the operator has to check and probably modify them for final approval. In this paper the generation scheduling from the viewpoint of a distribution system operator (DSO) is formulated. The traditional task of the DSO is securing network reliability and quality. The effectiveness of the proposed method is assessed by applying it to a 6-bus and 9-bus distribution system.

An efficient approach for trimming simulation of 3D forged components

Trimming operation as an important stage of many sheet and bulk metal processes is geometrically and physically complex and computationally challenging. This is especially true for metal forming processes where net-shape specification is critical. In this paper, we present an efficient approach for fast trimming simulation of 3D forged components so that the effect of such trimming operations on post-forming material spingback, thermal distortion and final dimensional and shape accuracy of formed parts can be quantified. This approach comprises steps including definition of trim line, elimination of discarded elements, adjustment of nodal positions close to the trim line and mapping of the state variables from the original mesh to the new mesh. To evaluate the effect of residual stresses in trimming operation, a new algorithm involving a scaling interpolation and coordinate transformation procedure is proposed so that limited 2D trimming simulations can be used to quantify and to map trimming induced residual stresses onto the whole 3D model for further process simulation. This developed trimming simulation approach was verified using an industry case study in hot forging of a 3D aerofoil blade by three post-forging cooling simulation cases including an untrimmed blade, a trimmed blade and a trimmed blade with the inclusion of trimming induced residual stresses. The simulation results were compared with actual measurement data of the forged aerofoil blade with excellent results obtained. The results show that the trimming operation has a significant effect on post-forging springback and thermal distortion but much less so on thickness of the aerofoil sections of the forged blade. The results also demonstrate that the proposed trimming simulation approach is computationally efficient and robust for other bulk and sheet metal forming processes of complex shapes.

Joint shape segmentation with linear programming

We present an approach to segmenting shapes in a heterogenous shape database. Our approach segments the shapes jointly, utilizing features from multiple shapes to improve the segmentation of each. The approach is entirely unsupervised and is based on an integer quadratic programming formulation of the joint segmentation problem. The program optimizes over possible segmentations of individual shapes as well as over possible correspondences between segments from multiple shapes. The integer quadratic program is solved via a linear programming relaxation, using a block coordinate descent procedure that makes the optimization feasible for large databases. We evaluate the presented approach on the Princeton segmentation benchmark and show that joint shape segmentation significantly outperforms single-shape segmentation techniques.

Dealing with the efficient allocation of scarce resources at congested airports

The existing slot allocation mechanism, based on the International Air Transport Association (IATA) system and its complementary version of the European Union (EU) regulation, produces rather poor capacity allocation outcomes for congested EU airports since it fails to properly match slots requested with slots allocated to airlines. Inefficiencies during the initial allocation are mainly due to the problem complexity in conjunction to limited decision support available to slot coordinators. On the other hand, substantial inefficiencies give rise to severe slot misuse and unreasonably low utilisation of airport resources running already into scarcity. The objective of this paper is to develop an optimisation-based model implementing the existing EU/IATA rules, operational constraints, and coordination procedures with the ultimate objective to better accommodate airlines’ preferences at coordinated airports through the minimisation of the difference between the requested and the allocated slot times to airlines. The results of the model are assessed and compared vis-à-vis the allocation outcome produced according to current slot coordination practice in three regional Greek airports. The proposed model produces very promising results and demonstrates that there is large room for improvement of the efficiency of the current allocation outcome in a range between 14% and 95%. The discussion of the model results is complemented by a sensitivity analysis highlighting the importance of declared capacity and the magnitude of its influence on slot allocation efficiency.

Synchronisation-based, multi-channel multi-interface medium access scheme in ad hoc network

Multi-channel multi-interface (MCMI) medium access can provide high-throughput services for wireless ad hoc networks. However, the multi-channel hidden terminal problem and the rendezvous problem must be addressed. This study aims to design a low-cost integrated solution to address the two problems, so as to fully exploit the available wireless interfaces and channels to enhance the network performance, especially the network aggregated throughput. The authors propose a new MCMI synchronisation-based media access control (SMAC) protocol with the operation of two interfaces. Unlike other studies, the authors propose a novel interface classification using a synchronisation interface (SynIF) and a normal interface (NorIF). A synchronisation mechanism and a new channel coordination procedure are operated on SynIF, and data packets can be transmitted on SynIF and NorIF concurrently. All control messages occur only in a variable-length channel coordination window (CCW) on a common control channel. The maximum length of CCW and network throughput are analysed mathematically and the performance of the protocol is validated in ns-2 simulator through comparisons with few other MCMI-MAC protocols. In IEEE 802.11-based multi-interface ad hoc networks, when using MCMI-SMAC, the results show that the network aggregated throughput is enhanced significantly and the protocol overhead is very low.

Overcurrent Relays Coordination Considering the Priority of Constraints

In interconnected networks, it is impossible to satisfy all coordination constraints. Some methods have been proposed in the literature to determine the minimum break point set (MBPS) before the coordination procedure. In this paper, a new method is presented which coordinates overcurrent relays and simultaneously determines minimum unsatisfied constraints as broken constraints (BCs). For the implementation of this method, a new objective function (OF) is defined that also includes constraints with various weightings. These weightings determine the priority of constraints for being satisfied which are obtained by means of some expert rules. The expert rules of previous papers are modified and weighted to determine the priority of constraints. The genetic algorithm is used to optimize the OF that has an internal feedback for determining the minimum BCs considering coordination criterion. The effectiveness of the proposed technique is demonstrated by comparing the results of two sample networks with those obtained by using the recently developed techniques.

Testing Coordination System through a Case Study

Coordination has been regarded as a critical factor of successful projects. Because construction projects are highly fragmented with many participants involved at different construction stages, coordination is more complicated for contractors. A coordination systems and procedure developed by simulating circulatory system could improve coordination effectiveness of construction projects due to the natural and effective physiological functions of the human body. To verify the applicability and effectiveness of the system and procedure, two tools to quantify coordination needs and supply were proposed and a case project was tested for ten months. The results showed that the more fit between coordination needs and supply, the better the task performance, meaning that the coordination system and procedure is effective. During construction the contractor can follow the coordination procedure and assign an engineer to evaluate variation of coordination needs and supply periodically or at emergent conditions. As coordination supply does not meet needs, time and frequency of coordination methods should be adjusted.

A Study on Coordinated Generation Maintenance Scheduling in Competitive Electricity Markets

A new approach to coordinated generation maintenance scheduling (GMS) in competitive electricity market, based on game theoretic framework, is presented. The main contribution of this paper can be focused on formulating the problem of ISO and modeling the coordination procedure. In competitive markets, the objective of generation company (genco) is to maximize the profits. The objective of ISO is to ensure reliability by increasing reserve capacity during peak period. The Genco and ISO determine their own GMS according to each objective, and then GMS of Genco is compared to that of ISO with ISO reliability criteria. If they are close enough, the GMS of Genco is determined as final GMS. Otherwise the coordination procedure is repeated until the GMS of Genco satisfies the ISO reliability criteria. Numerical results for two-Genco system are used to demonstrate the applicability of this framework for maintenance scheduling problem.