Priority Classification Research Articles

Bounds of the Overflow Priority Classification for Blocking Probability Approximation in OBS Networks: Errata

Bounds of the Overflow Priority Classification for Blocking Probability Approximation in OBS Networks: Errata

Blocking Probability Analysis of Circuit-Switched Networks With Long-Lived and Short-Lived Connections

We consider a circuit-switched network with nonhierarchical alternate routing and trunk reservation involving two types of connections that are modeled as long-lived and short-lived calls. The long-lived calls can be reserved well in advance, and the short-lived calls are provided on demand. Therefore, we assume that the long-lived calls have strict priority over the short-lived ones. We develop approximations for the estimation of the blocking probability based on the quasi-stationary approach in two ways. One uses the Erlang fixed-point approximation (EFPA), and the other uses the overflow priority classification approximation (OPCA). We compare the results of the approximations with simulation results and discuss the accuracy of the approximations under different system parameters, such as ratio of offered load, number of links per trunk, maximum allowable number of deflections, and trunk reservation. We also discuss the robustness of the quasi-stationary approximation to the ratio of the mean holding times of the long-lived and short-lived calls as well as that of EFPA and OPCA to the shape of the holding time distribution. Finally, we demonstrate that OPCA can be applied to a large network such as the Coronet.

On the Accuracy of the OPC Approximation for a Symmetric Overflow Loss Model

The overflow priority classification approximation (OPCA) and Erlang's fixed-point approximation (EFPA) are distinct methods for estimating blocking probabilities in overflow loss networks. Mounting numerical evidence has indicated that OPCA provides superior accuracy than EFPA in many circumstances. Furthermore, it has been proven that P EFPA ≤ P OPCA for a symmetric overflow loss network called the distributed server model, where P x is the blocking probability estimate yielded by approximation x ∈ {EFPA, OPCA}. The distributed server model is an ideal “proving ground” because the exact blocking probability, P exact, can be calculated with the Erlang B formula, yet the state dependencies caused by mutual overflow are retained. The present article proves the OPC Conjecture, P OPCA ≤ P exact. This new result establishes that OPCA is always equally or more accurate relative to EFPA for the distributed server model and suggests OPCA has utility in more general overflow loss networks. The proof of P OPCA ≤ P exact turned out to be challenging, since OPCA is remarkably close to the exact solution, requiring delicate inequality arguments on the Maclaurin series of both solutions. Another contribution is the derivation of new tight bounds and limiting regimes for the blocking probabilities yielded by OPCA and EFPA in the case of critical loading. The simple and tight lower bound derived for OPCA can serve as a tight lower bound for the Erlang B blocking probability in the case of critical loading.

Bounds of the Overflow Priority Classification for Blocking Probability Approximation in OBS Networks

It has been demonstrated that the overflow priority classification approximation (OPCA) is an accurate method for blocking probability evaluation for various networks and systems, including optical burst switched networks with deflection routing. OPCA is a hierarchical algorithm that requires fixed-point iterations in each layer of its hierarchy. This may imply a long running time. We prove here that the OPCA iterations alternately produce upper and lower bounds that consistently become closer to each other as more fixed-point iterations in each layer are used, and we demonstrate numerically that only a small number of iterations per layer are required for the bounds to be sufficiently close to each other. This behavior is demonstrated for various system parameters including offered load, number of channels per trunk, and maximum allowable number of deflections.

The WMSN Routing Protocol Based on Multiple QoS Constraints

In order to satisfy the data transmission in the wireless sensor multimedia network of several QoS constraints. This paper proposes a real-time and low energy consumption routing protocol on the basis of MMSPEED, This agreement inherits the advantages of MMSPEED protocol, multipath and priority classification data transmission. And at the same time, in the routing decisions this paper chooses fragmentary active routing decisions, further energy consumption and transmission delay reduction. The simulation results indicate that in the random node distribution, the agreement in real-time and prolong the network survival cycle, etc, have a good performance.

WSNHA-GAHR: a greedy and A* heuristic routing algorithm for wireless sensor networks in home automation

The use of wireless sensor networks in home automation (WSNHA) is a growing trend, on account of their self-organisation, low cost and potential for rapid deployment. Routing in WSNHA is a challenging research topic, because of the requirements of low energy consumption, low storage, low computational complexity, fast response, self-adaptation to unpredictable topological changes and robustness with respect to discontinuous interference. With the development of localisation techniques, localised routing offers a number of attractive benefits, but not all are suitable for WSNHA. In this study, the authors propose a new routing algorithm for WSNHA, called WSNHA-GAHR (greedy and A* heuristic routing for WSNHA). The algorithm uses greedy forwarding, based on the smallest Euclidean distance, to minimise the number of hops for data packet transmission, and thus conserve energy. It also automatically adjusts the route, using the A* heuristic algorithm, when local minimum problems and unpredictable topological changes occur in WSNHA. In addition, link priority classification gives WSNHA-GAHR a greater tolerance than ZigBee routing algorithm for discontinuous interference. Simulation results show that this routing protocol dramatically improves reliability and reduces average packet delay, without introducing additional overhead.

Development of pediatric wait time access targets

The effective management of wait times is a top priority for Canadians. Attention to date has largely focused on wait times for adult surgery. The purpose of this study was to develop surgical wait time access targets for children. Using nominal group techniques, expert panels reached consensus on prioritization levels for 574 diagnoses in 10 surgical disciplines for wait 1 (W1; time from primary care visit to surgical consultation) and wait 2 (W2; time from decision to operate to receipt of surgery). A 7-stage priority classification reflects the permissible timeframe for children to receive consultation (W1) or surgery (W2). Access targets by priority were linked to 574 diagnoses in 10 pediatric surgical subspecialties. The pediatric surgical wait time access targets are a standardized, comprehensive and consensus-based model that can be systematically applied to children's hospitals across Canada. Future research and evaluation on outcomes from this model will evaluate improved access to pediatric surgical care.

Investigation of Subjective Acoustical Attributes by Performers Through Ranking Data Analyses

This paper focuses on the acoustic perception of professional musicians performing on a stage or in an orchestra pit. A questionnaire was used to obtain a 'priority classification' of acoustical attributes to describe their requirements. The Borda count was chosen as the analysis method. As it is not suggested for subjective data ascribed to ordinal scales, it has been validated through a comparison with the more rigorous and suitable Condorcet method and a modified version of this method. The uncertainty assessment was taken into account and the Normalized Error was used to compare the results related to five orchestra-concert hall configurations and one orchestra-opera house configuration. The factors that influence the ranking have been investigated and the different acoustical conditions in the auditorium do not seem to have affected the answers. The results suggest the existence of possible orchestra and stage effects or other unknown systematic effects which were not considered in the final classification. The attributes pertaining to the accuracy of ensemble playing and the playing technique were judged to be more important than those related to the stage or pit acoustics, even though the quality of the playing aspects depends on the acoustics.

Prioridad de las prescripciones farmacéuticas a pacientes con insuficiencia cardíaca en un Servicio de Medicina Interna

Prescriptions provided to elderly patients with comorbidity on hospital discharge are usually complex. This study has aimed to know what proportion of drugs is considered essential by the prescribing doctors and the existing agreement on this qualification.Cross-sectional study.general acute care hospital.random sample of 60 hospital discharges in patients hospitalized due to heart failure between 2004 to 2006 with 540 prescribed drugs.independent review by two internal medicine specialists and qualification of each of prescribed drugs as essential, advisable or not indicated. Calculation of the proportion of prescriptions according to priority, global and by therapeutic groups, and of the agreement between reviewers.An average of 9 drugs (statistical deviation [SD] 2.4) and 13.5 daily takings (SD 4.6) by patient were prescribed on hospital discharge. The reviewers considered 68.4% of the prescriptions essential (95% confidence interval [CI], 65.5-71.2), advisable 25% (95% CI, 22.4-27.6) and not indicated 6.6% (95% CI, 5.1-8.1). An inverse relation between number of prescribed drugs and their proportion considered as essential was observed. Global agreement between reviewers in the classification of priority was relatively low: weighed Kappa 0.27 (95% CI, 0.19-0.36). More than 90% of the prescriptions were considered as essential in only 6 of the 15 therapeutic groups prescribed most, and good agreements in the qualification of their priority was only reached in 3 groups.A considerable proportion of the prescribed medication on hospital discharge in patients with heart failure was not considered essential. Agreement reached between the reviewers in this qualification was low.

Enhanced Blocking Probability Evaluation Method for Circuit-Switched Trunk Reservation Networks

We consider the problem of estimating steady-state blocking probability for circuit-switched networks that allow alternate routing with particular emphasis on networks protected by trunk reservation. We use a recently proposed blocking probability estimate, the Overflow Priority Classification Approximation (OPCA) as an alternative to the currently used Erlang's Fixed-Point Approximation (EFPA). We demonstrate empirically that OPCA provides a better blocking estimate than EFPA for circuit-switched networks with alternate routing, that are reasonably protected by trunk reservation.

Waiting times in a tertiary paediatric nephrology clinic

To the authors' knowledge, paediatric nephrology waiting times have not been previously studied. Given the high incidence of new referrals each year, the evaluation of the current waiting times would be beneficial in the management and triaging of new appointments. Using descriptive statistics, data from all appropriate paediatric nephrology referrals to the Children's Hospital of Eastern Ontario (Ottawa, Ontario) from 2003 to 2005 (n=1446) were retrospectively analyzed. The median waiting time from receipt of initial request for referral to first appointment was 111 days (range zero to 364 days). No significant variation existed throughout the duration of the study, despite the variation in the number of paediatric nephrology staff. Infants were seen significantly sooner than older children. There were no assigned priority classification levels based on referral reason. Critical conditions, such as macrohematuria, were seen on an urgent basis; all other patients were seen at the next available appointment slot, which was usually four months away. A significant proportion of patients were referred for dysfunctional voiding and enuresis (25.9%). These diagnoses are not generally considered a part of core nephrology. The waiting times for a paediatric nephrology appointment are long. Focusing on core nephrology business and appropriate triaging of consult would be necessary to implement a priority classification level-based appointment assignment. Additional resources would allow for more patients to be seen in a more timely fashion.

Policy and science in children's health and environment: Recommendations from the PINCHE project

Policy recommendations result from the discussions and analysis of the present situation in environment and health. Such analysis was performed in PINCHE. This led to recommendations based on the scientific literature. In the field of children's environmental health the policy process will follow more or less fixed rules, but this process is still at an early level of development. The link between science and policy still faces many challenges. Scientific assessment of environmental risk must recognize and tackle the problems of data sets, variability of human and environmental systems, the range, spatial and temporal diffusion of potential health effects and many biases and confounding factors. The PINCHE network recommends a general improvement of the supporting scientific fields in environment and health. Assessments from epidemiology or toxicology should play a key role in influencing science-policy decisions in programmes that are intended to inform the public policy process. Scientific committees at a local level could play a role. The relation between health and environment needs to be better incorporated in training and education. There is a need for harmonization of data production and use. The priorities in PINCHE focus on the most important issues. A classification of low, medium or high priority for action was used to describe a range of different environmental stressors. PINCHE provided recommendations to reduce exposure for children. Exposure reduction is not always linked to improved health in the short term, but it will reduce the body burden of accumulating chemicals in children. A strategic choice is reduction of exposure of children to compounds by changing production techniques or by increasing the distance of child specific settings to sources. The contribution of all players in the production, distribution and use of scientific knowledge in the field of children's environmental health is necessary.

Dam Failure Risk: Its Definition and Impact on Safety Assessment of Dam Structures

The dam structure is typical of facilities which are built to withstand unfavorable natural conditions. Of the 30 000 recorded dams worldwide, only a few are reported in any given year to fail. Structures must now meet design standards intended to make dams withstand extreme phenomena and disasters as damaging as maximum probable flood (MPF). New facilities are therefore safer. The existing facilities also have to conform to the new standards. Risk analysis is a new approach that has become more frequently used the last few years to assess the safety of dam facilities and to establish a priority classification which would make these facilities conform to the recently established standards. The failure of the dyke Cut-away in Saguenay (Canada), the study case referred to in this paper, shows the limits of conventional risk analysis methods. The latter would not clearly detect the dyke’s critical state; other methods of risk qualification are therefore proposed. These methods disclose supplementary aspects of the safety of the construction but they do not necessarily integrate hazards and consequences. The application of these methods to the identified objectives in our paper gives a synthesis of the risks posed by an unsafe construction. When viewed jointly, the methods and synthesis suggest the most effective ways to minimize those risks.

Priority Classification of Patients According to a Modified ‘Norwegian Model’

A priority classification was evaluated according to a modified 'Norwegian model.' Many diseases do not belong to any specific priority category based only on the diagnosis. The classification also depends on the condition's type, site, and phase as well as the patient's age and overall condition. Savings cannot be achieved by the model used because 89% of the patients belonged to the priority categories I-III, the care of which can be classified as necessary.

A novel neuro-fuzzy based self-correcting online electric load forecasting model

The paper presents a neuro-fuzzy short-term load forecasting (STLF) model. The proposed ANN function approximator models the relationships between the system hourly peak load and system variables affecting it, namely, weather and temperature variations, type and time of day, the inherent parameters of historical load patterns such as trend, cyclic oscillations, regular seasonal and irregular ‘special’ events. The load predictor forecasting input vector was extended to account for most of the input dominant variables affecting the short-term forecast load. The model utilizes a preprocessor for input vector generation and priority classifications using historical load and system data. A postprocessor fuzzy logic block provides error correction and data filtering and online tuning and adjustment of electric load forecast data.

The Implicit Triangulated Irregular Network and Multiscale Spatial Databases

The triangulated irregular network (TIN) provides a versatile and widely used approach to representing terrain models in a way that retains the original sample points, adapts to variation in data density and incorporates linear features corresponding to natural or man-made phenomena. Classification of the scale-related priority of the constituent points and linear features can be used to create hierarchical, multiresolution TIN representations. A large proportion of the data items included in conventional and hierarchical TIN data structures are concerned with recording the topology of the triangulation. Although TINs typically use many fewer points then the main alternative representation of regular rectangular grids, they do not usually occupy much less data storage, due to the topological data. This paper describes a novel multiresolution storage scheme which uses an approach termed the Implicit TIN, in which storage requirements are reduced significantly by storing only the vertices and constraining features. TIN topology is reconstructed by a procedure when required. The Implicit TIN storage scheme has been demonstrated in the context of an experimental multiscale database. Variable-scale access is provided to polygonal regions of a terrain model which includes polygon, line and point objects that constrain the constructed triangulated model.

Layered coding for ATM based video distribution systems

This paper discusses packet loss and its protection in an asynchronous transfer mode (ATM) based video distribution system. Packet losses in ATM based networks have such a great impact on the design of coding algorithms and network architectures that they should be exhaustively discussed and resolved. In this paper, first basic configuration of the ATM based video transmission system and its packet-loss protection schemes are discussed. The DCT based layered coding scheme with packet priority classification is proposed as an effective packet-loss protection scheme. Burstiness characteristics of the broadcast video sources are evaluated and modeled to clarify statistical multiplexing performance and packet-loss properties. The quality degradation caused by the packet losses is also evaluated by the SNR, and the superior performance of the proposed layered coding scheme is verified.

Variable bit-rate video transmission in the broadband ISDN environment

Many compensative measures have been proposed recently the make the cell loss in ATM (asynchronous transfer mode) networks subjectively imperceptible. These schemes include the simple automatic repeat quest (ARQ) scheme, error concealment by command refreshment, appropriate queueing disciple and priority switching design and layered source coding schemes. The authors summarize these efforts and, in particular, elaborate on different layered source coding schemes. Four types of signal priority classification schemes are identified: bit-plane separation (FDS) combined with bit-plane-frequency separation (CBFS), and feature plane separation (FPS). Different layered coding techniques are discussed and compared. Some open questions and recommendations are also presented for further research and study.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Priority cell discarding for overload control in BISDN/ATM networks: An analysis framework

AbstractThe broadband integrated services digital networks (BISDNs) of the future will use asynchronous transfer mode (ATM) for switching and transport of basic transport units called cells. These networks are likely to exhibit extremely bursty traffic characteristics which could cause significant queue overload conditions. This paper suggests that priority cell discarding, in which a delivery priority (also known as a loss priority) is assigned to each cell, is a viable alternative for controlling this overload. We also present a framework for the analysis and comparison of the performance of such priority discarding systems. The framework consists of a general analysis model appropriate for BISDNs using ATM, a two‐dimensional structural classification of priority discarding algorithms and suggestions for performance measures, one of which is a generalization of the often‐used throughput measure. We illustrate how this framework can be useful in systems analysis by introducing a specific discarding optimization problem.

Assessment of groundwater contamination resulting from a major accident in land nuclear power plants (LNPP), II: Evaluation of a melt-through event

Contamination assessment methodology for a point-source scenario is exemplified here for calcareous sand and sandstone aquifers. Contamination predictions were derived according to two major approaches: (a) Conservative, associated commonly with risk analyses, where parameter values are chosen to yield reasonably maximum predictions. (b) Probabilistic presentation of contamination hazards, providing the basis for making decisions according to a given acceptable risk level. Simulated contamination patterns indicates that 3H (tritium) and 129I, both presumably geochemically inert species, has the largest downstream pollution range; they are followed by 90Sr, 125Sb, 106Ru and 238Pu, whose magnitude of interaction with aquifer rocks under field conditions is still poorly documented. Since the overall hazard range is dictated in this case by geochemically inert species, this information-gap seems to be here of secondary importance. Sensitivity analyses of computed pollution ranges shows relatively low sensitivity to possible variations of nuclides inventory, dispersivity and effective thickness of aquifer formations, and high sensitivity to possible variations of the assumed true downstream velocities of released nuclides. Some possible means to reduce the potential groundwater pollution range of nuclear power plants are discussed to illuminate major findings of the presented risk assessment. Presented contamination analysis refers to a given region. The criteria for priority classification of alternative sites within that region are defined according to the contamination vulnerability of exploitable sites, remedial action requirements, and the predictability of nuclides spread in the aquifer.