Home About us Contact
|
Home About us Contact | ||
|
|
||
Reservations
Kinds of Reservations Terms modified by Reservations Selected AbstractsMARSH DEVELOPMENT AT RESTORATION SITES ON THE WHITE MOUNTAIN APACHE RESERVATION, ARIZONA,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 6 2003Jonathan W. Long ABSTRACT: To prioritize sites for riparian restoration, resource managers need to understand how recovery processes vary within landscapes. Complex relationships between watershed conditions and riparian development make it difficult to predict the outcomes of restoration treatments in the semiarid Southwest. Large floods in 1993 scoured riparian areas in the Carrizo watershed on the White Mountain Apache Reservation in east-central Arizona. We evaluated recovery at three of these sites using repeated photographs and measurements of channel cross sections and stream-side vegetation along permanent transects. The sites were mapped as lying on the same soil type, had similar streamside vegetative communities, and were similarly treated through livestock exclusion and supplemental seeding. However, the sites and individual reaches within the sites followed strikingly different development paths. Dramatic recovery occurred at a perennial reach where cover of emergent wetland plants increased from 4.7 percent (standard error = 0.8 percent) in October 1995 to 55.5 percent (standard error = 2.7 percent) in September 2001. At several other reaches, geologic and hydro geomorphic characteristics of the sites limited inputs of fine sediment or surface water, resulting in modest or negligible increases in emergent cover. Recovery efforts for highly valued marshlands in this region should prioritize perennial reaches in low gradient valleys where salty sediments are abundant. [source] Resource reservations with fuzzy requestsCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 13 2006T. Röblitz Abstract We present a scheme for reserving job resources with imprecise requests. Typical parameters such as the estimated runtime, the start time or the type or number of required CPUs need not be fixed at submission time but can be kept fuzzy in some aspects. Users may specify a list of preferences which guide the system in determining the best matching resources for the given job. Originally, the impetus for our work came from the need for efficient co-reservation mechanisms in the Grid where rigid constraints on multiple job components often make it difficult to find a feasible solution. Our method for handling fuzzy reservation requests gives the users more freedom to specify the requirements and it gives the Grid Reservation Service more flexibility to find optimal solutions. In the future, we will extend our methods to process co-reservations. We evaluated our algorithms with real workload traces from a large supercomputer site. The results indicate that our scheme greatly improves the flexibility of the solution process without having much affect on the overall workload of a site. From a user's perspective, only about 10% of the non-reservation jobs have a longer response time, and from a site administrator's view, the makespan of the original workload is extended by only 8% in the worst case. Copyright © 2006 John Wiley & Sons, Ltd. [source] The Effectiveness of Jobs Reservation: Caste, Religion and Economic Status in IndiaDEVELOPMENT AND CHANGE, Issue 3 2007Vani K. Borooah ABSTRACT This article investigates the effect of jobs reservation on improving the economic opportunities of persons belonging to India's Scheduled Castes (SC) and Scheduled Tribes (ST). Using employment data from the 55th NSS round, the authors estimate the probabilities of different social groups in India being in one of three categories of economic status: own account workers; regular salaried or wage workers; casual wage labourers. These probabilities are then used to decompose the difference between a group X and forward caste Hindus in the proportions of their members in regular salaried or wage employment. This decomposition allows us to distinguish between two forms of difference between group X and forward caste Hindus: ,attribute' differences and ,coefficient' differences. The authors measure the effects of positive discrimination in raising the proportions of ST/SC persons in regular salaried employment, and the discriminatory bias against Muslims who do not benefit from such policies. They conclude that the boost provided by jobs reservation policies was around 5 percentage points. They also conclude that an alternative and more effective way of raising the proportion of men from the SC/ST groups in regular salaried or wage employment would be to improve their employment-related attributes. [source] Growth and mortality of prairie stream fishes: relations with fish community and instream habitat characteristicsECOLOGY OF FRESHWATER FISH, Issue 2 2001M. C. Quist Abstract , Few studies have been conducted to describe the age structure, growth rates and mortality of fishes in small stream ecosystems. The purpose of this study was therefore to determine age structure, growth rates and mortality (i.e., total annual mortality and, age-specific mortality) of central stonerollers Campostoma anomalum, creek chubs Semotilus atromaculatus, red shiners Cyprinella lutrensis and green sunfish Lepomis cyanellus from 13 streams on Fort Riley Military Reservation, Kansas, using incremental growth analysis. Further, we were interested in determining the influence of fish community and instream habitat characteristics on growth rates. The age structure of central stonerollers, creek chubs, and red shiners was dominated by young individuals (i.e., less than age 2); however, over 60% of the green sunfish were age 2 to age 4. Mean total annual mortality was >60% for cyprinids and averaged approximately 44% for green sunfish. The age-specific mortality of central stonerollers and red shiners was generally less than 45% between age 0 and 1 and increased to over 85% for fishes greater than age 1. Fish community characteristics (e.g., catch per unit effort of trophic guilds) and chemical habitat (e.g., total phosphorous) were not related to growth rates (P>0.05). Growth of central stonerollers was not significantly correlated with physical habitat (P>0.05). However, the growth increments of creek chubs, red shiners, and green sunfish were related to the amount of woody debris (e.g., total woody debris, log complex habitat; r>0.60; P,0.05). The results of this study provide important information on the population dynamic rate functions of cyprinid and green sunfish populations in small prairie streams. Furthermore, these data suggest that woody debris is important habitat influencing growth of stream fishes., [source] Prevalence of epilepsy and seizures in the Navajo Nation 1998,2002EPILEPSIA, Issue 10 2009Karen Parko Summary Purpose:, To determine the prevalence of epilepsy and seizures in the Navajo. Methods:, We studied 226,496 Navajo residing in the Navajo Reservation who had at least one medical encounter between October 1, 1998 and September 30, 2002. We ascertained and confirmed cases in two phases. First, we identified patients with International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes signifying epilepsy or seizures using Indian Health Service (IHS) administrative data. Second, we reviewed medical charts of a geographic subpopulation of identified patients to confirm diagnoses and assess the positive predictive value of the ICD-9-CM codes in identifying patients with active epilepsy. Results:, Two percent of Navajo receiving IHS care were found to have an ICD-9-CM code consistent with epilepsy or seizures. Based on confirmed cases, the crude prevalence for the occurrence of any seizure (including febrile seizures and recurrent seizures that may have been provoked) in the geographic subpopulation was 13.5 per 1,000 and the crude prevalence of active epilepsy was 9.2 per 1,000. Prevalence was higher among males, children under 5 years of age, and older adults. Discussion:, The estimated prevalence of active epilepsy in the Navajo Nation is above the upper limit of the range of reported estimates from other comparable studies of U.S. communities. [source] Heterogeneity in informal sector mitigation of micro-enterprise credit rationingJOURNAL OF INTERNATIONAL DEVELOPMENT, Issue 5 2007David W. Mushinski Abstract Economists have observed that informal credit markets may mitigate micro-entrepreneurial rationing in formal credit markets. While informal credit markets may have that effect, the uniformity and magnitude of the mitigation is not apparent. We analyse micro-enterprise credit rationing on the Pine Ridge Indian Reservation in the United States. We find that micro-entrepreneurs have virtually no access to formal credit markets and that informal credit markets have differential impacts on micro-entrepreneurs' rationing in formal credit markets. Informal markets appear to ease credit rationing the most for the mid-size micro-enterprises in our sample, with the smallest and largest micro-enterprises still facing severe rationing constraints. We also find that micro-enterprises of all sizes face a positive probability of credit rationing. Copyright © 2006 John Wiley & Sons, Ltd. [source] MARSH DEVELOPMENT AT RESTORATION SITES ON THE WHITE MOUNTAIN APACHE RESERVATION, ARIZONA,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 6 2003Jonathan W. Long ABSTRACT: To prioritize sites for riparian restoration, resource managers need to understand how recovery processes vary within landscapes. Complex relationships between watershed conditions and riparian development make it difficult to predict the outcomes of restoration treatments in the semiarid Southwest. Large floods in 1993 scoured riparian areas in the Carrizo watershed on the White Mountain Apache Reservation in east-central Arizona. We evaluated recovery at three of these sites using repeated photographs and measurements of channel cross sections and stream-side vegetation along permanent transects. The sites were mapped as lying on the same soil type, had similar streamside vegetative communities, and were similarly treated through livestock exclusion and supplemental seeding. However, the sites and individual reaches within the sites followed strikingly different development paths. Dramatic recovery occurred at a perennial reach where cover of emergent wetland plants increased from 4.7 percent (standard error = 0.8 percent) in October 1995 to 55.5 percent (standard error = 2.7 percent) in September 2001. At several other reaches, geologic and hydro geomorphic characteristics of the sites limited inputs of fine sediment or surface water, resulting in modest or negligible increases in emergent cover. Recovery efforts for highly valued marshlands in this region should prioritize perennial reaches in low gradient valleys where salty sediments are abundant. [source] RECIRCULATING WELLS: GROUND WATER REMEDIATION AND PROTECTION OF SURFACE WATER RESOURCES,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 1 2000Keith W. Ryan ABSTRACT: Several chlorinated solvent plumes threaten the sole-source aquifer underlying the Massachusetts Military Reservation at the western end of Cape Cod. Sensitive surface water features including ponds, cranberry bogs, and coastal wetlands are hydraulically connected to the aquifer. For one of the plumes (CS-10 the original remedy of 120 extraction and reinjection wells has the potential for significant disruption of surface water hydrology, through the localized drawdown and mounding of the water table. Recirculating wells with in-well air stripping offer a cost-effective alternative to conventional pump-and-treat technology that does not adversely affect the configuration of the water table. Pilot testing of a two well system, pumping 300 gpm, showed a capture radius of > 200 feet per well, in-well trichloroethylene (TCE) removal efficiencies of 92 to 98 percent per recirculation cycle, an average of three recirculation cycles within the capture zone, and no measurable effect on water table elevations at any point within the recirculation/treatment zone. During 120 days of operation, the mean concentration of TCE in the treatment zone was reduced by 83 percent, from 1,111 ,g/l to 184 ,g/l. Full-scale design projections indicate that 60 wells at an average spacing of 160 feet, having an aggregate recirculation 11 MGD, can contain the CS-b plume without ground water extraction or adverse hydraulic effects on surface water resources. The estimated capital costs for such a system are about $7 million, and annual operations-and-maintenance costs should be about $1.4 million, 40 percent of those associated with a pump and treat system over a 20-year period. [source] Mortality of older construction and craft workers employed at department of energy (DOE) nuclear sitesAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 9 2009John M. Dement PhD Abstract Background The U.S. Department of Energy (DOE) established medical screening programs at the Hanford Nuclear Reservation, Oak Ridge Reservation, the Savannah River Site, and the Amchitka site starting in 1996. Workers participating in these programs have been followed to determine their vital status and mortality experience through December 31, 2004. Methods A cohort of 8,976 former construction workers from Hanford, Savannah River, Oak Ridge, and Amchitka was followed using the National Death Index through December 31, 2004, to ascertain vital status and causes of death. Cause-specific standardized mortality ratios (SMRs) were calculated based on US death rates. Results Six hundred and seventy-four deaths occurred in this cohort and overall mortality was slightly less than expected (SMR,=,0.93, 95% CI,=,0.86,1.01), indicating a "healthy worker effect." However, significantly excess mortality was observed for all cancers (SMR,=,1.28, 95% CI,=,1.13,1.45), lung cancer (SMR,=,1.54, 95% CI,=,1.24,1.87), mesothelioma (SMR,=,5.93, 95% CI,=,2.56,11.68), and asbestosis (SMR,=,33.89, 95% CI,=,18.03,57.95). Non-Hodgkin's lymphoma was in excess at Oak Ridge and multiple myeloma was in excess at Hanford. Chronic obstructive pulmonary disease (COPD) was significantly elevated among workers at the Savannah River Site (SMR,=,1.92, 95% CI,=,1.02,3.29). Conclusions DOE construction workers at these four sites were found to have significantly excess risk for combined cancer sites included in the Department of Labor' Energy Employees Occupational Illness Compensation Program (EEOCIPA). Asbestos-related cancers were significantly elevated. Am. J. Ind. Med. 52:671,682, 2009. © 2009 Wiley-Liss, Inc. [source] Lessons learned from a small native American communityPUBLIC ADMINISTRATION & DEVELOPMENT, Issue 5 2002Wendy Nelson Espeland The decision not to build Orme Dam was a great political victory for residents of the Fort McDowell Indian Reservation in central Arizona. This article examines the conditions that gave rise to what most considered an unlikely outcome, and the lessons it suggests for understanding the politics of large water projects. These lessons include the importance of understanding that rationality takes multiple forms; that how value is expressed can be as significant as what, and how much, something is valued; that identity politics which elaborates and celebrates cultural differences can be an effective means for challenging even powerful bureaucracies; and that law can be an important mediating structure in the politics of bureaucratic decision-making. Copyright © 2002 John Wiley & Sons, Ltd. [source] Peaks and troughs,an exploration of patient perspectives of dangerous and severe personality disorder assessment (Peaks Unit, Rampton Hospital)PERSONALITY AND MENTAL HEALTH, Issue 1 2008Lisa Maltman Rationale,Although accessing user-perspectives is a key National Health Service initiative, the literature reporting user's views of forensic services, particularly dangerous and severe personality disorder (DSPD) services, is in its infancy. Aim and Design,This qualitative study applied thematic analysis to 12 semi-structured interviews aimed to enhance professional understanding of how Peaks Unit treatment-ward participants retrospectively perceive their experience of being admitted and assessed at the unit. Findings,Reported themes include ,fear' associated with participants' personal safety concerns and apprehensions regarding inhumane treatment and prolonged detention. The local metaphor of the DSPD Unit as the ,dark side' exacerbated such fears. ,Shock' also emerged as a primary theme resulting from unexpected admissions, security measures and some staff responses. ,Offering hope' provided a further theme with many participants reporting a climate of therapeutic optimism within staff teams and ,refreshing' opportunities for change. Reservations were also expressed about the service potentially offering ,false hope'. Several suggestions are proposed for future assessment strategy including escalating user-involvement activity, managing expectations, promoting therapeutic optimism and helping patients to attain a realistic sense of hope in order to maximise therapeutic engagement. Copyright © 2008 John Wiley & Sons, Ltd. [source] Legislating Development through Welfare Reform: Indiscernible Jobs, Insurmountable Barriers, and Invisible Agendas on the Pine Ridge and Rosebud Indian ReservationsPOLAR: POLITICAL AND LEGAL ANTHROPOLOGY REVIEW, Issue 1 2001Kathleen Pickering First page of article [source] Allotment of Mineral and Timber Lands on Indian Reservations and the Public DomainTHE HISTORIAN, Issue 4 2005Henry E. Fritz First page of article [source] Design and realization of the cooperative work system based on equipments sharingCOMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 4 2009Bo Yan Abstract With analysis on the necessity and functions of the equipments sharing platform and the cooperative work system for colleges and universities, this paper designs the cooperative work system to provide cooperative support for resource query and reservation. The system classifies users' resource application roles, divides users' application information into different cooperative grades, and provides a basis for users' cooperative work. Functions, authorization, page flow, operating methods, and relevant database table of cooperative roles are shown in detail. At the same time, the ASP system will be introduced into the system, and a special fee management system will be established for effective management of the system. Functions and page flow of the fee management system are also designed. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 17: 372,378, 2009; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20195 [source] Market-based grid resource co-allocation and reservation for applications with hard deadlinesCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 18 2009Kurt Vanmechelen Abstract Grid computing technology enables the creation of large-scale IT infrastructures that are shared across organizational boundaries. In such shared infrastructures, conflicts between user requirements are common and originate from the selfish actions that users perform when formulating their service requests. The introduction of economic principles in grid resource management offers a promising way of dealing with these conflicts. We develop and analyze both a centralized and a decentralized algorithm for economic grid resource management in the context of compute bound applications with deadline-based quality of service requirements and non-migratable workloads. Through the use of reservations, we co-allocate resources across multiple providers in order to ensure that applications finish within their deadline. An evaluation of both algorithms is presented and their performance in terms of realized user value is compared with an existing market-based resource management algorithm. We establish that our algorithms, which operate under a more realistic workload model, can closely approximate the performance of this algorithm. We also quantify the effect of allowing local workload preemption and different scheduling heuristics on the realized user value. Copyright © 2009 John Wiley & Sons, Ltd. [source] Threshold-based admission control for a multimedia Grid: analysis and performance evaluationCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 14 2006Yang Zhang Abstract In a Grid-based services system facing a large number of requests with different services and profits significance, there is always a trade-off between the system profits and the Quality of Service (QoS). In such systems, admission control plays an important role: the system has to employ a proper strategy to make admission control decisions and reserve resources for the coming requests thus to achieve greater profits without violating the QoS of the requests already admitted. In this paper, we introduce three essential admission control strategies with threshold on resource reservation and a newly proposed strategy with layered threshold. Through comprehensive theoretical analyses and extensive simulations, we demonstrate that the strategy with layered threshold is more efficient and flexible than the existing strategies for Grid-based multimedia services systems. Copyright © 2006 John Wiley & Sons, Ltd. [source] The Effectiveness of Jobs Reservation: Caste, Religion and Economic Status in IndiaDEVELOPMENT AND CHANGE, Issue 3 2007Vani K. Borooah ABSTRACT This article investigates the effect of jobs reservation on improving the economic opportunities of persons belonging to India's Scheduled Castes (SC) and Scheduled Tribes (ST). Using employment data from the 55th NSS round, the authors estimate the probabilities of different social groups in India being in one of three categories of economic status: own account workers; regular salaried or wage workers; casual wage labourers. These probabilities are then used to decompose the difference between a group X and forward caste Hindus in the proportions of their members in regular salaried or wage employment. This decomposition allows us to distinguish between two forms of difference between group X and forward caste Hindus: ,attribute' differences and ,coefficient' differences. The authors measure the effects of positive discrimination in raising the proportions of ST/SC persons in regular salaried employment, and the discriminatory bias against Muslims who do not benefit from such policies. They conclude that the boost provided by jobs reservation policies was around 5 percentage points. They also conclude that an alternative and more effective way of raising the proportion of men from the SC/ST groups in regular salaried or wage employment would be to improve their employment-related attributes. [source] Foot abnormalities in Canadian Aboriginal adolescents with Type 2 diabetesDIABETIC MEDICINE, Issue 7 2007J. Chuback Abstract Aims To determine the profile of foot abnormalities in Canadian Aboriginal adolescents with Type 2 diabetes and the risk factors associated with these abnormalities. Methods Aboriginal adolescents with Type 2 diabetes underwent an interview, medical record review and foot examination in a tertiary care, paediatric hospital diabetes clinic and two geographically remote outreach clinics. The notes of 110 subjects were reviewed [mean age 15 ± 3 years; mean duration of diabetes, 30 ± 20 months; 71 (66%) female and 39 (34%) male] and 77 (70%) of the subjects were examined. Results Foot abnormalities were identified by either interview or notes review, and included poor toenail condition in 85 (77%), paronychia in 29 (26%), ingrowing toenails in 16 (15%) and neuropathic symptoms in 13 (12%) subjects. Foot abnormalities were identified by examination in many subjects, including poor toenail condition in 38 (49%), calluses in 34 (44%) and paronychia in 13 (17%) subjects. Eighteen (24%) of 75 subjects did not have running water in the home. Factors that significantly increased the presence of foot abnormalities included: foot care provided by a person other than self; absence of running water in the home; decreased frequency of bathing; and decreased frequency of nail clipping. A greater percentage of subjects living on a reservation or rural community had specialized consultations for retinal examination, footwear, or both than of those living in an urban or unknown residence. Conclusions A high prevalence of foot abnormalities was noted in Aboriginal adolescents with Type 2 diabetes. These findings highlight the associated comorbidities in this population, emphasizing the need for early detection and intervention. [source] Evaluating reserves for species richness and representation in northern CaliforniaDIVERSITY AND DISTRIBUTIONS, Issue 4 2006Jeffrey R. Dunk ABSTRACT The Klamath-Siskiyou forests of northern California and southern Oregon are recognized as an area of globally outstanding biological distinctiveness. When evaluated at a national or global level, this region is often, necessarily, considered to be uniformly diverse. Due to large variation in biotic and abiotic variables throughout this region, however, it is unlikely that biological diversity is uniformly distributed. Furthermore, land management decisions nearly always occur at spatial scales smaller than this entire region. Therefore, we used field data from a random sampling design to map the distribution of local and regional richness of terrestrial molluscs and salamanders within northern California's portion of the Klamath-Siskiyou region. We also evaluated the protection afforded by reserves established for varying reasons (e.g. for inspiration and recreation for people vs. species conservation) to hotspots of species richness and species representation of these taxa. No existing reserves were created with these taxa in mind, yet it was assumed that reserves established largely around considerations for the northern spotted owl (Strix occidentalis caurina) would afford adequate protection for many lesser-known species. Species of terrestrial molluscs and salamanders share two general features: (1) they have extremely low vagility, and (2) they are often associated with moist, cool microclimates. Existing reserves disproportionately included areas of hotspots of species richness for both taxa, when hotspots included the richest c. 25% of the area, whereas non-reserved lands contained greater than expected areas with lower species richness. However, when a more strict definition of hotspot was used (i.e. the richest c.10% of areas), local hotspots for both taxa were not disproportionately found in reserves. Reserves set aside largely for human aesthetics and recreation and those set aside for biodiversity both contributed to the protection of areas with high (greatest 25%) species richness. Existing biodiversity reserves represented 68% of mollusc species and 73% of salamander species, corresponding to the 99th and 93rd percentiles, respectively, of species representation achieved by simulating a random distribution of the same total area of reservation. Cumulatively, however, reserves set aside for inspiration and biodiversity represented 83% of mollusc species and 91% of salamander species. The existing reserves provide conservation value for terrestrial molluscs and salamanders. This reserve network, however, should not be considered optimal for either taxa. [source] Women as Policy Makers: Evidence from a Randomized Policy Experiment in IndiaECONOMETRICA, Issue 5 2004Raghabendra Chattopadhyay This paper uses political reservations for women in India to study the impact of women's leadership on policy decisions. Since the mid-1990's, one third of Village Council head positions in India have been randomly reserved for a woman: In these councils only women could be elected to the position of head. Village Councils are responsible for the provision of many local public goods in rural areas. Using a dataset we collected on 265 Village Councils in West Bengal and Rajasthan, we compare the type of public goods provided in reserved and unreserved Village Councils. We show that the reservation of a council seat affects the types of public goods provided. Specifically, leaders invest more in infrastructure that is directly relevant to the needs of their own genders. [source] QoS in IntServ-based IP networks: the peak rate policingEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 4 2003Lorenzo Battaglia In the last few years, IP has moved towards resource reservation, with the task to guarantee in the future Quality of Service (QoS). This has led to flow admission control algorithms based on the negotiation of standardised traffic parameters. QoS can be guaranteed in any network, a priori from the used technology, only if the used admission control algorithm wisely shares the network's resources among the users. Any admission control algorithm on its turn can do so, only if every user respects the negotiated traffic parameters. Since any user could, maliciously or not, send at a higher rate than negotiated, i.e. use a higher share of resources than the negotiated one, in every network in which admission control is performed, a policing algorithm is used. An ideal policer should guarantee to reject no packet of a well-behaved user and police contract violation as rigidly as possible. All this independently of the characteristics of the monitored stream and of the background traffic. This holds also for Integrated Services (IS) based IP networks. In these networks, every user negotiates a peak and an average rate. In this paper we present the solution to the peak rate policing issue. We adapt the Generic Cell Rate Algorithm (GCRA), well-known policer used in ATM networks, to police the peak rate of flows of packets with variable length. We intuitively call this modified GCRA Generic Packet Rate Algorithm (GPRA) and dimension its parameters so that independently of the characteristics of the policed flow and of the background traffic, no packets of a well-behaved user are rejected and that the flows of any misbehaving user are rigidly policed. Copyright © 2003 AEI. [source] A distributed adaptive guard channel reservation scheme for cellular networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 9 2007H.K. Pati Abstract In this paper, a distributed adaptive guard channel reservation (DAGCR) scheme is proposed to give priority to handoff calls. This scheme is built upon the concept of guard channels and it uses an adaptive algorithm to search automatically the optimal number of guard channels to be reserved at each base station. The quality-of-service (QoS) parameters used are the new and handoff call blockings. Simulation studies are performed to compare the present algorithm with the static guard channel policy. Simulation results show that this proposed algorithm guarantees the handoff call blocking probability to remain below the targeted threshold up to a substantially high offered load with a minimal blocking to new calls up to a moderate offered load and also shows significantly high channel utilization in all offered load conditions. This scheme is examined over a wide range of offered load. Thus, it seems the proposed scheme is very useful in controlling the blocking performances in wireless cellular networks. Copyright © 2006 John Wiley & Sons, Ltd. [source] Improving node behaviour in a QoS control environment by means of load-dependent resource redistributions in LANs,INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 4 2005Bernd E. Wolfinger Abstract An important means to guarantee an acceptable quality of service in networks with real-time communication requirements is the reservation of resources at connection setup time. However, such reserved resources, e.g. transmission bandwidth, may be unused as a consequence of the variations in the actual resource demands. Therefore, a more efficient resource utilization is possible if communicating stations or end-users dynamically hand over some of the free resources temporarily to the other communication partners, e.g. of a ,broadcast network'. This paper concentrates on two fundamental problems of such a demand-based sharing of resources: on the one hand, estimation of the current resource requirement on the basis of load measurements is investigated and, on the other hand, we elaborate efficient algorithms for resource sharing respecting real-time requirements. The algorithms proposed for load estimation and for resource sharing are evaluated analytically with respect to their efficiency for worst-case, average-case and realistic load scenarios. Our approach suggested for resource and traffic management allows one to achieve significantly better utilization of network resources. Copyright © 2005 John Wiley & Sons, Ltd. [source] The study of handoff prediction schemes for resource reservation in mobile multimedia wireless networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 6 2004Li-Liann Lu Abstract In this paper, the mobility-dependent predictive resource reservation (MDPRR) scheme is proposed to provide flexible usage of scarce resource in mobile multimedia wireless networks. An admission control scheme is also considered to further guarantee the QoS of real-time traffic. The area of a cell is divided into non-handoff, pre-handoff, and handoff zones so that bandwidth is reserved in the target/sub-target cell as mobile stations move into the pre-handoff zone and leave the serving base station. The amount of bandwidth to be reserved is dynamically adjusted according to the location, the instantaneous variation of velocity and direction of mobile stations. Two scenarios of the MDPRR scheme are compared by considering the velocity threshold in the calculation of the weight of direction. A number of designs are investigated to further enhance the performance of the proposed scheme. The results show that employing the velocity threshold in the MDPRR scheme can indeed reduce connection dropping probability, and make better usage of the reserved bandwidth. Copyright © 2004 John Wiley & Sons, Ltd. [source] Using a multiple priority reservation MAC to support differentiated services over HFC systems,INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 4 2002J. D. Angelopoulos Abstract The successful commercial deployment of Hybrid Fibre/Coaxial (HFC) access networks in the residential market has so far been driven by demand for faster Internet access and the prospects of a host of new services based on real-time voice and video. To sustain their growth rates and compete with alternative approaches, such as ADSL, they must be enhanced with the capability to efficiently handle quality-intensive real-time services. The new multi-service paradigm mandates isolation of traffic classes, conditioning of entering traffic and preventive control in addition to traditional closed-loop control. The differentiated services (DiffServ) architecture with its relevant traffic control tools and the bundling of behaviour aggregates is particularly suited to the H/W-based MAC of HFC systems. It constitutes a suitable framework enabling the support of proliferating real-time voice- and video-based services while aligning the system to the emerging Internet strategy of scalable service differentiation. The implementation of such a solution in the ACTS 327AROMA research project is presented in this paper. The performance of the system is evaluated using computer simulation. Copyright © 2002 John Wiley & Sons, Ltd. [source] A multiple access protocol with explicit and implicit reservationINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 3 2001F. Davoli Abstract A new version of a MAC-level protocol is introduced and investigated, operating in a cellular environment, where a base station co-ordinates mobile users within each cell. The channel multiplexing structure is based on time division, and the slots in each frame are dynamically assigned to the users and their service classes by the cell base station. Decisions are taken on the basis of binary channel feedback information (collision/no collision), by assuming independence in the presence of packets at the mobile stations, and aim at maximizing the one-step throughput in the current frame. The frame is divided into two periods: the first (short) one contains a number of minislots, equal to the number of ,real' slots (i.e. those capable of containing a fixed size packet) of the second part. At the beginning of the frame, the access rights are computed and broadcast to the users; the enabled stations that have a packet to transmit respond, by sending a short burst that contains their ID in a minislot. This most recent feedback is used at the base station to update the parameters of the decision algorithm, which is then re-applied to yield the final access rights for the second part of the frame. The performance of the scheme is analysed by simulation in the presence of mixed voice and data traffic, and compared with those of a reservation random access protocol using the same algorithm in a single-phase fashion (RRA-ISA) and PRMA. Copyright © 2001 John Wiley & Sons, Ltd. [source] Reducing cell loss in banyan based ATM switching fabricsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 1 2001M. Al-Mouhamed Abstract In this paper, we propose a new technique for reducing cell loss in multi-banyan-based ATM switching fabrics. We propose a switch architecture that uses incremental path reservation based on previously established connections. Path reservation is carried out sequentially within each banyan but multiple banyan planes can be concurrently reserved. We use a conflict resolution approach according to which banyans make concurrent reservation offers of conflict-free paths to head of the line cells waiting in input buffers. A reservation offer from a given banyan is allocated to the cell whose source-to-destination path uses the largest number of partially allocated switching elements which are shared with previously reserved paths. Paths are incrementally clustered within each banyan. This approach leaves the largest number of free switching elements for subsequent reservations which has the effect of reducing the potential of future conflicts and improves throughput. We present a pipelined switch architecture based on the above concept of path-clustering which we call path-clustering banyan switching fabric (PCBSF). An efficient hardware that implements PCBSF is presented together with its theoretical basis. The performance and robustness of PCBSF are evaluated under simulated uniform traffic and ATM traffic. We also compare the cell loss rate of PCBSF to that of other pipelined banyan switches by varying the switch size, input buffer size, and traffic pattern. Copyright © 2001 John Wiley & Sons, Ltd. [source] Using virtual topologies to manage inter-domain QoS in next-generation networksINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 3 2010Ricardo B. Freitas Recently, several computer fields have turned to virtualization as a way to simplify complex problems. In this context, the Virtual Topology Service (VTS) was created to manage the advertisement and acquisition of virtual topologies (abstractions of the network status of a domain) and their use in inter-domain resource reservation to provide end-to-end quality of service (QoS). As an effort to create new network architectures which could attend current requirements like mobility and context-aware applications and support autonomous, heterogeneous and mobile domains next-generation networks (NGNs) emerged, with Ambient Networks (AN) as one of its instances. With an ever increasing multitude of online applications, end-to-end QoS has become increasingly important, especially for media and real-time uses. In this context, in order to better manage inter-domain QoS in these new networks, better coping with mobile nodes and domains, this work presents a new design and implementation of the VTS, adapted to the AN environment. The new VTS stores resource reservation information to enable the reuse of these reservations when re-establishing QoS after a node/domain movement. This implementation was tested on a real NGN prototype and showed considerable time saving when compared to QoS re-establishment without reusing the reservations. Copyright © 2009 John Wiley & Sons, Ltd. [source] An adaptive resource reservation for vehicular mobile networksINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 5 2009I. Ben Hamida This paper presents the time-based bandwidth reservation (TBR) algorithm, suitable for handoff management in cellular systems. TBR is based on real-time measurements of mobile stations (position, velocity and acceleration). The scheme consists in sending reservation requests to the neighboring cells based on an extrapolation of the user's motion. The originality of our approach lies in dynamically adjusting the amount of time for which bandwidth has to be allocated and reserved in a cell. In addition, we propose an optimal channel requests arrangement (CRA) algorithm in order to improve the performance of TBR in terms of resource utilization. Finally, we propose VTBR, an adapted and extended version of TBR for better support of vehicular network specificities where service degradation or forced call termination may occur owing to frequent handoffs. Detailed simulation results for TBR and VTBR schemes and a comparison with the guard channel scheme are presented. The results show that TBR and VTBR can efficiently improve the flow dropping probability. Copyright © 2008 John Wiley & Sons, Ltd. [source] Dynamic scheduling of network resources with advance reservations in optical gridsINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 2 2008Savera Tanwir Advance reservation of lightpaths in grid environments is necessary to guarantee QoS and reliability. In this paper, we have evaluated and compared several algorithms for dynamic scheduling of lightpaths using a flexible advance reservation model. The main aim is to find the best scheduling policy for a grid network resource manager that improves network utilization and minimizes blocking. The scheduling of lightpaths involves both routing and wavelength assignment. Our simulation results show that minimum-cost adaptive routing where link costs are determined by the current and future usage of the link provides the minimum blocking. For wavelength assignment, we have used a scheme that reduces fragmentation by minimizing unused gaps. We have also analyzed approaches for failure recovery and resource optimization. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||