Science.gov

Sample records for acceptance bandwidth approaching

  1. Approaches to acceptable risk

    SciTech Connect

    Whipple, C.

    1997-04-30

    Several alternative approaches to address the question {open_quotes}How safe is safe enough?{close_quotes} are reviewed and an attempt is made to apply the reasoning behind these approaches to the issue of acceptability of radiation exposures received in space. The approaches to the issue of the acceptability of technological risk described here are primarily analytical, and are drawn from examples in the management of environmental health risks. These include risk-based approaches, in which specific quantitative risk targets determine the acceptability of an activity, and cost-benefit and decision analysis, which generally focus on the estimation and evaluation of risks, benefits and costs, in a framework that balances these factors against each other. These analytical methods tend by their quantitative nature to emphasize the magnitude of risks, costs and alternatives, and to downplay other factors, especially those that are not easily expressed in quantitative terms, that affect acceptance or rejection of risk. Such other factors include the issues of risk perceptions and how and by whom risk decisions are made.

  2. Approaches to acceptable risk: a critical guide

    SciTech Connect

    Fischhoff, B.; Lichtenstein, S.; Slovic, P.; Keeney, R.; Derby, S.

    1980-12-01

    Acceptable-risk decisions are an essential step in the management of technological hazards. In many situations, they constitute the weak (or missing) link in the management process. The absence of an adequate decision-making methodology often produces indecision, inconsistency, and dissatisfaction. The result is neither good for hazard management nor good for society. This report offers a critical analysis of the viability of various approaches as guides to acceptable-risk decisions. This report seeks to define acceptable-risk decisions and to examine some frequently proposed, but inappropriate, solutions. 255 refs., 22 figs., 25 tabs.

  3. In acceptance we trust? Conceptualising acceptance as a viable approach to NGO security management.

    PubMed

    Fast, Larissa A; Freeman, C Faith; O'Neill, Michael; Rowley, Elizabeth

    2013-04-01

    This paper documents current understanding of acceptance as a security management approach and explores issues and challenges non-governmental organisations (NGOs) confront when implementing an acceptance approach to security management. It argues that the failure of organisations to systematise and clearly articulate acceptance as a distinct security management approach and a lack of organisational policies and procedures concerning acceptance hinder its efficacy as a security management approach. The paper identifies key and cross-cutting components of acceptance that are critical to its effective implementation in order to advance a comprehensive and systematic concept of acceptance. The key components of acceptance illustrate how organisational and staff functions affect positively or negatively an organisation's acceptance, and include: an organisation's principles and mission, communications, negotiation, programming, relationships and networks, stakeholder and context analysis, staffing, and image. The paper contends that acceptance is linked not only to good programming, but also to overall organisational management and structures. PMID:23278470

  4. A new approach to family planning acceptance.

    PubMed

    Shukla, M

    1979-01-01

    The integrated approach to MCH/FP service delivery in the India Population Project is based on the assumption that positive results on family planning acceptance depend upon better health of children already born and a decline in the mortality rate. The Auxiliary Nurse and Midwife (ANM) performs all the family planning activities, distributes a nutritional supplement ("Balahar") to pregnant women, lactating mothers, and children between 6 months and 2 years, and keeps a record of births and deaths in order to convince the village population of the advantages of family planning. In 1975 a house to house inquiry was conducted in one of the affected villages to gather demographic and nutritional information. Analysis revealed that 77 of 82 eligible children were receiving "Balahar". The village birth rate was calculated at 50.3 per thousand and the death rate at 18.5 per thousand. Only 4 out of 233 family planning target couples were current users, and only 11 target couples were favorably disposed to family planning, while 94 were neutral and 128 were hostile. None of the 3 eligible women were receiving prenatal care, and only 1 of the 20 eligible women was receiving postnatal care. PMID:12261422

  5. Optical tweezers: Characterization and systems approach to high bandwidth force estimation

    NASA Astrophysics Data System (ADS)

    Sehgal, Hullas

    In recent times, the hard boundaries between classical fields of sciences have almost disappeared. There is a cross-pollination of ideas between sciences, engineering and mathematics. This work investigates a modern tool of micro-manipulation of microscopic particles that is used primarily by bio-physicists and bio-chemists for single cell, single molecule studies. This tool called the Optical Tweezers can trap microscopic dielectric particles using radiation pressure of light. Optical tweezers is increasingly being used in bio-assays as it provides a means to observe bio-molecules non invasively and offers a spatial resolution in nanometers and force resolution in femto-Newtons at millisecond timescales. In this work, physics governing the operating principle behind optical tweezers is presented, followed by a step by step procedure to build an optical tweezers system having measurement and actuation capability along with a controller logic for feedback implementation. The working of optical tweezers system is presented using a spring mass damper model and the traditional methods of optical tweezers characterization are discussed. A comprehensive view of Optical tweezers is then presented from a system theoretic perspective, underlying the limitations of traditional methods of tweezers characterization that are based on the first principle. The role of feedback in Optical tweezers is presented along with the fundamental limitations that the plant model imposes on optical tweezers performance to be used as a force sensor for fast dynamics input force. The purpose of optical tweezers as a pico-newton force probe is emphasized and a classical controls based method to improve the bandwidth of force estimation using an ad-hoc approach of system inversion is presented. The efficacy of system inversion based method in improving the force probe capability of feedback enhanced optical tweezers is validated by experimental results. It is shown experimentally that the system

  6. The promise of acceptance as an NGO security management approach.

    PubMed

    Fast, Larissa; Freeman, Faith; O'Neill, Michael; Rowley, Elizabeth

    2015-04-01

    This paper explores three questions related to acceptance as a security management approach. Acceptance draws upon relationships with community members, authorities, belligerents and other stakeholders to provide consent for the presence and activities of a non-governmental organisation (NGO), thereby reducing threats from these actors. Little is documented about how NGOs gain and maintain acceptance, how they assess and monitor the presence and degree of acceptance, or how they determine whether acceptance is effective in a particular context. Based on field research conducted in April 2011 in Kenya, South Sudan and Uganda, we address each of these three issues and argue that acceptance must be actively sought as both a programme and a security management strategy. In the paper we delineate elements common to all three contexts as well as missed opportunities, which identify areas that NGOs can and should address as part of an acceptance approach. PMID:25440000

  7. A Column-Generation and Branch-and-Cut Approach to the Bandwidth-Packing Problem.

    PubMed

    Villa, Christine; Hoffman, Karla

    2006-01-01

    The telecommunications problem of assigning calls with point to point demand to a capacitated network where each call can be assigned to at most one path has been called the Bandwidth-Packing Problem. For a given network, with specified arc costs and arc capacities, one wishes to route calls (defined by a starting and ending point) through the network to maximize the profit from the calls routed. Each such call is single path routed and not all calls will be routed. We propose a branch-and-cut methodology coupled with column generation to optimally solve such problems. We examine the alternative approaches in the literature and explain how this new method takes the best of all components of methods suggested previously. The method we suggest is new in that it includes a linear programming-based heuristic for obtaining good lower bounds, uses lifted minimal covers that take into account special-ordered set constraints, and dynamically choose among three alternative branching strategies. In addition, whenever a new column is generated, it is lifted into all existing cuts. We also discuss the need to generate all tied optimal linear optimization solutions if one wishes to assure that the solution obtained is optimal. Our computational results provide solutions to problems previously unsolvable. PMID:27274927

  8. Microbicide acceptability research: current approaches and future directions.

    PubMed

    Mantell, Joanne E; Myer, Landon; Carballo-Diéguez, Alex; Stein, Zena; Ramjee, Gita; Morar, Neetha S; Harrison, Polly F

    2005-01-01

    With growing recognition of the potential value of microbicides for HIV/STI prevention, the importance of the acceptability of this brand-new technology has been widely acknowledged. We review the current body of microbicide acceptability research, characterize the limitations in assessment approaches, and suggest strategies for improvement. Electronic databases and abstracts of recent meetings were searched for acceptability data regarding vaginal and rectal products that may be used for HIV prevention. Of the 61 studies reviewed, more than half assessed acceptability based primarily on the description of a hypothetical microbicide, or with the demonstration of a spermicide or lubricant. Physical characteristics of microbicidal products, their effects after insertion, and their effects on sensation during intercourse (for both partners) were the dimensions most frequently assessed (measured in 77%, 49% and 49% of studies, respectively). Attention to the social context of use was inadequate. As acceptability is likely to be a key determinant in the use-effectiveness of microbicides, in-depth understanding of the social processes that shape microbicide acceptability across diverse populations will become increasingly valuable. This includes exploring the effects that sexual partners, health care providers, and key opinion leaders have on the acceptability of microbicides among women and men, including youth and people living with HIV. Future research will benefit from studies of the acceptability of other contraceptive-barrier methods (especially the female condom), use of an agreed-upon operationalization of acceptability, use of acceptability assessments within clinical trials, expansion of measurement domains, and assessment of changes in perceptions of acceptability and use over time. Failure to understand the key factors associated with microbicide acceptability is likely to hinder the adoption and continued use of products that are effective in preventing HIV

  9. A mechanism design approach to bandwidth allocation in tactical data networks

    NASA Astrophysics Data System (ADS)

    Mour, Ankur

    The defense sector is undergoing a phase of rapid technological advancement, in the pursuit of its goal of information superiority. This goal depends on a large network of complex interconnected systems - sensors, weapons, soldiers - linked through a maze of heterogeneous networks. The sheer scale and size of these networks prompt behaviors that go beyond conglomerations of systems or `system-of-systems'. The lack of a central locus and disjointed, competing interests among large clusters of systems makes this characteristic of an Ultra Large Scale (ULS) system. These traits of ULS systems challenge and undermine the fundamental assumptions of today's software and system engineering approaches. In the absence of a centralized controller it is likely that system users may behave opportunistically to meet their local mission requirements, rather than the objectives of the system as a whole. In these settings, methods and tools based on economics and game theory (like Mechanism Design) are likely to play an important role in achieving globally optimal behavior, when the participants behave selfishly. Against this background, this thesis explores the potential of using computational mechanisms to govern the behavior of ultra-large-scale systems and achieve an optimal allocation of constrained computational resources Our research focusses on improving the quality and accuracy of the common operating picture through the efficient allocation of bandwidth in tactical data networks among self-interested actors, who may resort to strategic behavior dictated by self-interest. This research problem presents the kind of challenges we anticipate when we have to deal with ULS systems and, by addressing this problem, we hope to develop a methodology which will be applicable for ULS system of the future. We build upon the previous works which investigate the application of auction-based mechanism design to dynamic, performance-critical and resource-constrained systems of interest

  10. Breaking the trade-off: rainforest bats maximize bandwidth and repetition rate of echolocation calls as they approach prey

    PubMed Central

    Schmieder, Daniela A.; Kingston, Tigga; Hashim, Rosli; Siemers, Björn M.

    2010-01-01

    Both mammals and birds experience a performance trade-off between producing vocalizations with high bandwidths and at high repetition rate. Echolocating bats drastically increase repetition rate from 2–20 calls s−1 up to about 170 calls s−1 prior to intercepting airborne prey in order to accurately track prey movement. In turn, bandwidth drops to about 10–30 kHz for the calls of this ‘final buzz’. We have now discovered that Southeast Asian rainforest bats (in the vespertilionid subfamilies Kerivoulinae and Murininae) are able to maintain high call bandwidths at very high repetition rates throughout approach to prey. Five species of Kerivoula and Phoniscus produced call bandwidths of between 78 and 170 kHz at repetition rates of 140–200 calls s−1 and two of Murina at 80 calls s−1. The ‘typical’ and distinct drop in call frequency was present in none of the seven species. This stands in striking contrast to our present view of echolocation during approach to prey in insectivorous bats, which was established largely based on European and American members of the same bat family, the Vespertilionidae. Buzz calls of Kerivoula pellucida had mean bandwidths of 170 kHz and attained maximum starting frequencies of 250 kHz which makes them the most broadband and most highly pitched tonal animal vocalization known to date. We suggest that the extreme vocal performance of the Kerivoulinae and Murininae evolved as an adaptation to echolocating and tracking arthropods in the dense rainforest understorey. PMID:20356884

  11. Got Bandwidth?

    ERIC Educational Resources Information Center

    Villano, Matt

    2009-01-01

    Video-heavy distance learning programs can put a strain on the campus network. This article describes how three institutions are managing bandwidth to ensure high-quality service for eLearning students.

  12. New approaches in the derivation of acceptable daily intake (ADI)

    SciTech Connect

    Dourson, M.L.

    1986-01-01

    Current methods for estimating human health risks from exposure to threshold-acting toxicants in water or food, such as those established by the U.S. EPA, the FDA, the NAS, the WHO and the FAO, consider only chronic or lifetime exposure to individual chemicals. These methods generally estimate a single, constant daily intake rate which is low enough to be considered safe or acceptable. The intake rate is termed the acceptable daily intake (ADI). Two problems with the approach have been recognized. The first problem is that the method does not readily account for the number of animals used to determine the appropriate 'no-observed-effect-level' (NOEL). The second problem with the current approach is that the slope of the dose-response curve of the critical toxic effect is generally ignored in estimating the ADI. The report illustrates both a revised approach to estimate ADIs with all toxicity data which includes methods for partial lifetime assessment, and novel methods for ADI estimation with quantal or continuous toxicity data. The latter method addresses to a degree the common problems with the current approach.

  13. The indicator performance estimate approach to determining acceptable wilderness conditions

    NASA Astrophysics Data System (ADS)

    Hollenhorst, Steven; Gardner, Lisa

    1994-11-01

    Using data from a study conducted in the Cranberry Wilderness Area of West Virginia, United States, this paper describes how a modified importance—performance approach can be used to prioritize wilderness indicators and determine how much change from the pristine is acceptable. The approach uses two key types of information: (1) indicator importance, or visitor opinion as to which wilderness indicators have the greatest influence on their experience, and (2) management performance, or the extent to which actual indicator conditions exceed or are within visitor expectations. Performance was represented by calculating indicator performance estimates (IPEs), as defined by standardized differences between actual conditions and visitor preferences for each indicator. The results for each indicator are then presented graphically on a four-quadrant matrix for objective interpretation. Each quadrant represents a management response: keep up the good work, concentrate here, low priority, or possible overkill. The technique allows managers to more systematically and effectively utilize information routinely collected during the limits of acceptable change wilderness planning process.

  14. Analytical method transfer: new descriptive approach for acceptance criteria definition.

    PubMed

    de Fontenay, Gérald

    2008-01-01

    Within the pharmaceutical industry, method transfers are now commonplace during the life cycle of an analytical method. Setting acceptance criteria for analytical transfers is, however, much more difficult than usually described. Criteria which are too wide may lead to the acceptance of a laboratory providing non-equivalent results, resulting in bad release/reject decisions for pharmaceutical products (a consumer risk). On the contrary, criteria which are too tight may lead to the rejection of an equivalent laboratory, resulting in time costs and delay in the transfer process (an industrial risk). The consumer risk has to be controlled first. But the risk does depend on the method capability (tolerance to method precision ratio). Analytical transfers were simulated for different scenarios (different method capabilities and transfer designs, 10,000 simulations per test). The results of the simulations showed that the method capability has a strong influence on the probability of success of its transfer. For the transfer design, the number of independent analytical runs to be performed on a same batch has much more influence than the number of replicates per run, especially when the inter-day variability of the method is high. A classic descriptive approach for analytical method transfer does not take into account the variability of the method, and therefore, no risks are controlled. Tools for designing analytical transfers and defining a new descriptive acceptance criterion, which take into account the intra- and inter-day variability of the method, are provided for a better risk evaluation by non-statisticians. PMID:17961955

  15. When is diagnostic testing inappropriate or irrational? Acceptable regret approach.

    PubMed

    Hozo, Iztok; Djulbegovic, Benjamin

    2008-01-01

    The authors provide a new model within the framework of theories of bounded rationality for the observed physicians' behavior that their ordering of diagnostic tests may not be rational. Contrary to the prevailing thinking, the authors find that physicians do not act irrationally or inappropriately when they order diagnostic tests in usual clinical practice. When acceptable regret (i.e., regret that a decision maker finds tolerable upon making a wrong decision) is taken into account, the authors show that physicians tend to order diagnostic tests at a higher level of pretest probability of disease than predicted by expected utility theory. They also show why physicians tend to overtest when regret about erroneous decisions is extremely small. Finally, they explain variations in the practice of medicine. They demonstrate that in the same clinical situation, different decision makers might have different acceptable regret thresholds for withholding treatment, for ordering a diagnostic test, or for administering treatment. This in turn means that for some decision makers, the most rational strategy is to do nothing, whereas for others, it may be to order a diagnostic test, and still for others, choosing treatment may be the most rational course of action. PMID:18480041

  16. Current migraine management – patient acceptability and future approaches

    PubMed Central

    Fumal, Arnaud; Schoenen, Jean

    2008-01-01

    Despite its high prevalence and individual as well as societal burden, migraine remains underdiagnosed and undertreated. In recent years, the options for the management of migraine patients have greatly expanded. A number of drugs belonging to various pharmacological classes and deliverable by several routes are now available both for the acute and the preventive treatments of migraine. Nevertheless, disability and satisfaction remain low in many subjects because treatments are not accessible, not optimized, not effective, or simply not tolerated. There is thus still considerable room for better education, for more efficient therapies and for greater support from national health systems. In spite of useful internationally accepted guidelines, anti-migraine treatment has to be individually tailored to each patient taking into account the migraine subtype, the ensuing disability, the patient’s previous history and present expectations, and the co-morbid disorders. In this article we will summarize the phenotypic presentations of migraine and review recommendations for acute and preventive treatment, highlighting recent advances which are relevant for clinical practice in terms of both diagnosis and management. PMID:19337450

  17. Investigating Acceptance toward Mobile Learning to Assist Individual Knowledge Management: Based on Activity Theory Approach

    ERIC Educational Resources Information Center

    Liaw, Shu-Sheng; Hatala, Marek; Huang, Hsiu-Mei

    2010-01-01

    Mobile devices could facilitate human interaction and access to knowledge resources anytime and anywhere. With respect to wide application possibilities of mobile learning, investigating learners' acceptance towards it is an essential issue. Based on activity theory approach, this research explores positive factors for the acceptance of m-learning…

  18. Targeting Fear of Spiders with Control-, Acceptance-, and Information-Based Approaches

    ERIC Educational Resources Information Center

    Wagener, Alexandra L.; Zettle, Robert D.

    2011-01-01

    The relative impact of control-, acceptance-, and information-based approaches in targeting a midlevel fear of spiders among college students was evaluated. Participants listened to a brief protocol presenting one of the three approaches before completing the Perceived-Threat Behavioral Approach Test (PT-BAT; Cochrane, Barnes-Holmes, &…

  19. Constructing Acceptable RWM Approaches: The Politics of Participation

    SciTech Connect

    Laes, E.; Bombaerts, G.

    2006-07-01

    Public participation in a complex technological issue such as the management of radioactive waste needs to be based on a simultaneous construction of scientific, ethical and socio-political foundations. Confronting this challenge is in no way straightforward. The problem is not only that the 'hard' technocrats downplay the importance of socio-political and ethical factors; also, our 'soft' ethical vocabularies (e.g. Habermasian 'discourse ethics') seem to be ill-equipped for tackling such complex questions (in terms of finding concrete solutions). On the other hand, professionals in the field, confronted with a (sometimes urgent) need for finding workable solutions, cannot wait for armchair philosophers to formulate the correct academic answers to their questions. Different public participation and communication models have been developed and tested in real-world conditions, for instance in the Belgian 'partnership approach' to the siting of a low-level waste management facility. Starting from the confrontation of theoretical outlooks and pragmatic solutions, this paper identifies a number of 'dilemmas of participation' that can only be resolved by inherently political choices. Successfully negotiating these dilemmas is of course difficult and conditional on many contextual factors, but nevertheless at the end of the paper an attempt is made to sketch the contours of three possible future scenarios (each with their own limits and possibilities). (authors)

  20. Defining Acceptable Levels for Ecological Indicators: An Approach for Considering Social Values

    NASA Astrophysics Data System (ADS)

    Smyth, Robyn L.; Watzin, Mary C.; Manning, Robert E.

    2007-03-01

    Ecological indicators can facilitate an adaptive management approach, but only if acceptable levels for those indicators have been defined so that the data collected can be interpreted. Because acceptable levels are an expression of the desired state of the ecosystem, the process of establishing acceptable levels should incorporate not just ecological understanding but also societal values. The goal of this research was to explore an approach for defining acceptable levels of ecological indicators that explicitly considers social perspectives and values. We used a set of eight indicators that were related to issues of concern in the Lake Champlain Basin. Our approach was based on normative theory. Using a stakeholder survey, we measured respondent normative evaluations of varying levels of our indicators. Aggregated social norm curves were used to determine the level at which indicator values shifted from acceptable to unacceptable conditions. For seven of the eight indicators, clear preferences were interpretable from these norm curves. For example, closures of public beaches because of bacterial contamination and days of intense algae bloom went from acceptable to unacceptable at 7-10 days in a summer season. Survey respondents also indicated that the number of fish caught from Lake Champlain that could be safely consumed each month was unacceptably low and the number of streams draining into the lake that were impaired by storm water was unacceptably high. If indicators that translate ecological conditions into social consequences are carefully selected, we believe the normative approach has considerable merit for defining acceptable levels of valued ecological system components.

  1. Analytical methodology for determination of helicopter IFR precision approach requirements. [pilot workload and acceptance level

    NASA Technical Reports Server (NTRS)

    Phatak, A. V.

    1980-01-01

    A systematic analytical approach to the determination of helicopter IFR precision approach requirements is formulated. The approach is based upon the hypothesis that pilot acceptance level or opinion rating of a given system is inversely related to the degree of pilot involvement in the control task. A nonlinear simulation of the helicopter approach to landing task incorporating appropriate models for UH-1H aircraft, the environmental disturbances and the human pilot was developed as a tool for evaluating the pilot acceptance hypothesis. The simulated pilot model is generic in nature and includes analytical representation of the human information acquisition, processing, and control strategies. Simulation analyses in the flight director mode indicate that the pilot model used is reasonable. Results of the simulation are used to identify candidate pilot workload metrics and to test the well known performance-work-load relationship. A pilot acceptance analytical methodology is formulated as a basis for further investigation, development and validation.

  2. Parental acceptability of the watchful waiting approach in pediatric acute otitis media

    PubMed Central

    Broides, Arnon; Bereza, Olga; Lavi-Givon, Noga; Fruchtman, Yariv; Gazala, Eli; Leibovitz, Eugene

    2016-01-01

    AIM: To determine parental knowledge about acute otitis media (AOM) and its antibiotic therapy, antibiotic resistance and the willingness to comply with the watchful waiting (WW) approach in primary care settings in southern Israel. METHODS: The study was conducted in 3 primary care clinics and the pediatric emergency room of Soroka University Medical Center. Questionnaires (20 questions on education background, previous AOM experience, knowledge on antimicrobial resistance and attitude vs the WW approach) were filled by 600 parents (150 at each centers) of children < 6 years of age. RESULTS: Mothers represented 69% of parents; 2% had an education of < 10 school years, 46% had high-school education and 17% had an academic degree. 69% parents reported previous experience with AOM and 56% thought that antibiotics represent the only treatment for AOM. Knowledge on bacterial resistance to antibiotics was reported by 57% of the parents; 86% parents were willing to accept/probably accept the WW approach for their children. Logistic regression analysis revealed a significant association between parental education and knowledge about bacterial resistance to antibiotics and that previous experience with AOM was significantly associated with reluctance to accept the WW approach. More parents with knowledge on bacterial resistance were willing to accept the WW approach compared with parents without such knowledge. No correlation was found between the education level and willingness to accept the WW approach. CONCLUSION: A significant correlation was found between previous parental education and experience with AOM and the knowledge about antibiotic use, bacterial resistance and acceptance of the WW approach. PMID:27170930

  3. HIV vaccine acceptability among immigrant Thai residents in Los Angeles: a mixed-method approach.

    PubMed

    Lee, Sung-Jae; Brooks, Ronald A; Newman, Peter A; Seiden, Danielle; Sangthong, Rassamee; Duan, Naihua

    2008-11-01

    This study examined HIV vaccine acceptability among immigrant Thai residents in Los Angeles, California. We combined a qualitative research method (focus groups) with an innovative market research method (conjoint analysis). Focus groups explored social issues, concerns, barriers and motivators associated with HIV vaccine acceptability. Conjoint analysis was used to assess preferences among eight hypothetical HIV vaccines with varying attribute profiles and the impact of various attributes on acceptability. Five main themes were identified in the focus groups regarding acceptance and utilization of preventive HIV vaccines: (1) vaccine characteristics, such as efficacy, physical side-effects and cost, (2) fear of a vaccine, (3) vaccine acceptability and optimism, (4) social and family responses and (5) behavioral disinhibition. Conjoint analysis revealed HIV vaccine acceptability ranging from 7.4 (SD = 19.4) to 85.2 (SD = 24.3) across eight hypothetical vaccines. The vaccine with the highest acceptability had the following attributes: 99% efficacy, no side-effects, 10 years of protection, protects against one sub-type, free, one dose and given by injection. Vaccine efficacy had the greatest impact on acceptability (51.4, p=.005), followed by side-effects (11.1, p=.005) and duration of protection (8.3, p=.005). Despite some apprehensions and concerns, Thai residents perceived an HIV vaccine as making an important contribution to society and to protecting oneself and one's family from HIV infection. Nevertheless, acceptability of a partially efficacious vaccine may be low, suggesting the need for tailored social marketing interventions that might emphasize a collectivistic rather than an individualistic focus. Assessing HIV vaccine acceptability using a mixed-method approach is feasible with Thai residents and should lend itself to HIV vaccine research with other Asian Pacific Islander populations in the US. PMID:18608068

  4. Network Bandwidth Utilization Forecast Model on High Bandwidth Network

    SciTech Connect

    Yoo, Wucherl; Sim, Alex

    2014-07-07

    With the increasing number of geographically distributed scientific collaborations and the scale of the data size growth, it has become more challenging for users to achieve the best possible network performance on a shared network. We have developed a forecast model to predict expected bandwidth utilization for high-bandwidth wide area network. The forecast model can improve the efficiency of resource utilization and scheduling data movements on high-bandwidth network to accommodate ever increasing data volume for large-scale scientific data applications. Univariate model is developed with STL and ARIMA on SNMP path utilization data. Compared with traditional approach such as Box-Jenkins methodology, our forecast model reduces computation time by 83.2percent. It also shows resilience against abrupt network usage change. The accuracy of the forecast model is within the standard deviation of the monitored measurements.

  5. An Acceptance and Mindfulness-Based Approach to Social Phobia: A Case Study

    ERIC Educational Resources Information Center

    Brady, Victoria Popick; Whitman, Sarah M.

    2012-01-01

    Over the past few years, there has been a proliferation of theoretical discussions and empirical research on the use of acceptance and mindfulness-based therapies to treat anxiety disorders. Because these treatment approaches are in their infancy, many clinicians may still be uncertain about how to apply such treatments in their work with clients.…

  6. Using Financial Information in Continuing Education. Accepted Methods and New Approaches.

    ERIC Educational Resources Information Center

    Matkin, Gary W.

    This book, which is intended as a resource/reference guide for experienced financial managers and course planners, examines accepted methods and new approaches for using financial information in continuing education. The introduction reviews theory and practice, traditional and new methods, planning and organizational management, and technology.…

  7. An improved scheduled traffic model utilizing bandwidth splitting in elastic optical networks

    NASA Astrophysics Data System (ADS)

    Vyas, Upama; Prakash, Shashi

    2016-07-01

    The surge of traffic in today's networks gave birth to elastic optical networking paradigm. In this paper, first we propose to use the scheduled traffic model (STM) in elastic optical networks (EONs) to ensure guaranteed availability of resources to demands which enter into the network with a predetermined start and end times. In optical networks, such demands are referred to as scheduled lightpath demands (SLDs). To increase the amount of bandwidth accepted in network, next we introduce a time aware routing and spectrum assignment (TA-RSA) approach. We observed that provisioning of bulky SLDs has become more challenging in EONs due to enforcement of RSA constraints. To address this challenge, we improve the proposed STM and designed three heuristics for its implementation in EONs. In this work, we collectively refer to these heuristics as bandwidth segmented RSA (BSRSA). The improved STM (iSTM) allows splitting of SLDs in bandwidth dimension by utilizing the knowledge of attributes viz. demand holding time, overlapping in time and bandwidth requested by SLDs. Our numerical results show that BSRSA consistently outperformed over TA-RSA under all distinctive experimental cases that we considered and achieved fairness in serving heterogeneous bandwidth SLDs. The impact of splitting on the number and capacity of transponders at nodes is also gauged. It is observed that ingenious splitting of demands increases the number of resources (on links and nodes) used, and their utilization, leading to an increase in bandwidth accepted in the network.

  8. Acceptance of chronic neuropathic pain in spinal cord injured persons: a qualitative approach.

    PubMed

    Henwood, Penelope; Ellis, Jacqueline; Logan, Jo; Dubouloz, Claire-Jehanne; D'Eon, Joyce

    2012-12-01

    Chronic neuropathic pain (CNP) in spinal cord injury (SCI) is a significant problem that has physical, functional, and psychosocial repercussions beyond the consequences of SCI. The notion that acceptance may be a viable alternative to suffering when resolution of pain is unattainable was explored. Studies indicate that acceptance of pain is associated with lower pain intensity, less pain-related anxiety and avoidance, less depression, less physical and psychosocial disability, more daily active time, and improved work status in patients who have other types of chronic pain. This exploratory qualitative study examined acceptance of pain in SCI individuals who have CNP. Grounded theory was used to develop a conceptual framework to describe acceptance in people with CNP and SCI. Data were obtained from in-depth interviews with seven SCI individuals. Six phases were identified, including: "comprehending the perplexity of CNP," "seeking pain resolution," "acknowledging pain permanence," "redefining core values," "learning to live with the pain," and "integrating pain." Two driving forces, "increasing independence" and "evolving pain view," were noted to move the process of acceptance forward. The findings in this study suggest that acceptance of pain appeared to be beneficial in terms of reducing suffering and facilitating a more satisfying and fulfilling life in these SCI individuals. A decreased emphasis on continued searching for a cure for CNP and movement toward a self-management approach was associated with increased pain coping for these SCI individuals. Clinical implications suggest that early intervention to facilitate effective coping and an exploration of the notion of acceptance could be beneficial. PMID:23158703

  9. Chemical Industry Bandwidth Study

    SciTech Connect

    none,

    2006-12-01

    The Chemical Bandwidth Study provides a snapshot of potentially recoverable energy losses during chemical manufacturing. The advantage of this study is the use of "exergy" analysis as a tool for pinpointing inefficiencies.

  10. Glass Industry Bandwidth Analysis

    SciTech Connect

    Rue, David M.

    2006-07-01

    This is a study on energy use and potential savings, or "bandwidth" study, for several glassmaking processes. Intended to provide a realistic estimate of the potential amount of energy that can be saved in an industrial process, the "bandwidth" refers to the difference between the amount of energy that would be consumed in a process using commercially available technology versus the minimum amount of energy needed to achieve those same results.

  11. Industrial Glass Bandwidth Analysis

    SciTech Connect

    Rue, David M.; Servaites, James; Wolf, Warren

    2007-08-01

    This is a study on energy use and potential savings, or "bandwidth" study, for several glassmaking processes. Intended to provide a realistic estimate of the potential amount of energy that can be saved in an industrial process, the "bandwidth" refers to the difference between the amount of energy that would be consumed in a process using commercially available technology versus the minimum amount of energy needed to achieve those same results.

  12. Acceptability of impregnated school uniforms for dengue control in Thailand: a mixed methods approach

    PubMed Central

    Murray, Natasha; Jansarikij, Suphachai; Olanratmanee, Phanthip; Maskhao, Pongsri; Souares, Aurélia; Wilder-Smith, Annelies; Kittayapong, Pattamaporn; Louis, Valérie R.

    2014-01-01

    Background As current dengue control strategies have been shown to be largely ineffective in reducing dengue in school-aged children, novel approaches towards dengue control need to be studied. Insecticide-impregnated school uniforms represent an innovative approach with the theoretical potential to reduce dengue infections in school children. Objectives This study took place in the context of a randomised control trial (RCT) to test the effectiveness of permethrin-impregnated school uniforms (ISUs) for dengue prevention in Chachoengsao Province, Thailand. The objective was to assess the acceptability of ISUs among parents, teachers, and principals of school children involved in the trial. Methodology Quantitative and qualitative tools were used in a mixed methods approach. Class-clustered randomised samples of school children enrolled in the RCT were selected and their parents completed 321 self-administered questionnaires. Descriptive statistics and logistic regression were used to analyse the quantitative data. Focus group discussions and individual semi-structured interviews were conducted with parents, teachers, and principals. Qualitative data analysis involved content analysis with coding and thematic development. Results The knowledge and experience of dengue was substantial. The acceptability of ISUs was high. Parents (87.3%; 95% CI 82.9–90.8) would allow their child to wear an ISU and 59.9% (95% CI 53.7–65.9) of parents would incur additional costs for an ISU over a normal uniform. This was significantly associated with the total monthly income of a household and the educational level of the respondent. Parents (62.5%; 95% CI 56.6–68.1) indicated they would be willing to recommend ISUs to other parents. Conclusions Acceptability of the novel tool of ISUs was high as defined by the lack of concern along with the willingness to pay and recommend. Considering issues of effectiveness and scalability, assessing acceptability of ISUs over time is

  13. Estimating maximum and psychophysically acceptable hand forces using a biomechanical weakest link approach.

    PubMed

    Fischer, Steven L; Dickerson, Clark R; Wells, Richard P

    2014-01-01

    Accurate estimation of occupational performance capability facilitates better job (re-) design by informing workplace parties about the potential mismatches between job demands and the capability of their labour force. However, estimating occupational performance requires consideration of multiple factors that may govern capacity. In this paper, a novel model is described that uses a stochastic algorithm to estimate how variability in underlying biomechanical constraints affects hand force capability. In addition, the model estimates psychophysically acceptable hand force capacity thresholds by applying a biomechanical weakest link approach. Model estimates were tested against experimentally determined maximal and psychophysically determined hand forces in two exertion directions in constrained postures. The model underestimated maximum hand force capacity relative to measured maximum hand force by 30% and 35% during downward pressing and horizontal pulling, respectively. These values are consistent with those observed using previous two-dimensional models. Psychophysically acceptable hand forces were also underestimated by 29% during both pressing and pulling. Since the psychophysical estimates were scaled as a percentage of the estimated maximum capacity, this suggests that the underestimation in both predictions may be corrected by improving estimates of maximum hand force. Psychophysically acceptable forces were observed to be partially governed by demands at the biomechanical weakest link. PMID:23210453

  14. Participatory approach, acceptability and transparency of waste management LCAs: Case studies of Torino and Cuneo

    SciTech Connect

    Blengini, Gian Andrea; Fantoni, Moris; Busto, Mirko; Genon, Giuseppe; Zanetti, Maria Chiara

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer Life Cycle Assessment is still not fully operational in waste management at local scale. Black-Right-Pointing-Pointer Credibility of WM LCAs is negatively affected by assumptions and lack of transparency. Black-Right-Pointing-Pointer Local technical-social-economic constraints are often not reflected by WM LCAs. Black-Right-Pointing-Pointer A participatory approach can increase acceptability and credibility of WM LCAs. Black-Right-Pointing-Pointer Results of a WM LCA can hardly ever be generalised, thus transparency is essential. - Abstract: The paper summarises the main results obtained from two extensive applications of Life Cycle Assessment (LCA) to the integrated municipal solid waste management systems of Torino and Cuneo Districts in northern Italy. Scenarios with substantial differences in terms of amount of waste, percentage of separate collection and options for the disposal of residual waste are used to discuss the credibility and acceptability of the LCA results, which are adversely affected by the large influence of methodological assumptions and the local socio-economic constraints. The use of site-specific data on full scale waste treatment facilities and the adoption of a participatory approach for the definition of the most sensible LCA assumptions are used to assist local public administrators and stakeholders showing them that LCA can be operational to waste management at local scale.

  15. Low-bandwidth authentication.

    SciTech Connect

    Donnelly, Patrick Joseph; McIver, Lauren; Gaines, Brian R.; Anderson, Erik; Collins, Michael Joseph; Thomas,Kurt Adam; McDaniel, Austin

    2007-09-01

    Remotely-fielded unattended sensor networks generally must operate at very low power--in the milliwatt or microwatt range--and thus have extremely limited communications bandwidth. Such sensors might be asleep most of the time to conserve power, waking only occasionally to transmit a few bits. RFID tags for tracking or material control have similarly tight bandwidth constraints, and emerging nanotechnology devices will be even more limited. Since transmitted data is subject to spoofing, and since sensors might be located in uncontrolled environments vulnerable to physical tampering, the high-consequence data generated by such systems must be protected by cryptographically sound authentication mechanisms; but such mechanisms are often lacking in current sensor networks. One reason for this undesirable situation is that standard authentication methods become impractical or impossible when bandwidth is severely constrained; if messages are small, a standard digital signature or HMAC will be many times larger than the message itself, yet it might be possible to spare only a few extra bits per message for security. Furthermore, the authentication tags themselves are only one part of cryptographic overhead, as key management functions (distributing, changing, and revoking keys) consume still more bandwidth. To address this problem, we have developed algorithms that provide secure authentication while adding very little communication overhead. Such techniques will make it possible to add strong cryptographic guarantees of data integrity to a much wider range of systems.

  16. Broad Bandwidth Telecommunications Systems.

    ERIC Educational Resources Information Center

    Sodolski, John

    Broad bandwidth transmission systems have been around for years. They include microwave, assorted cable systems, and recently, satellites. With the exception of some privately owned systems, broadband services have been furnished by the common carriers. Recently, a new element has been added--Cable Antenna Television (CATV) distribution systems.…

  17. Intelligent bandwidth compression

    NASA Astrophysics Data System (ADS)

    Tseng, D. Y.; Bullock, B. L.; Olin, K. E.; Kandt, R. K.; Olsen, J. D.

    1980-02-01

    The feasibility of a 1000:1 bandwidth compression ratio for image transmission has been demonstrated using image-analysis algorithms and a rule-based controller. Such a high compression ratio was achieved by first analyzing scene content using auto-cueing and feature-extraction algorithms, and then transmitting only the pertinent information consistent with mission requirements. A rule-based controller directs the flow of analysis and performs priority allocations on the extracted scene content. The reconstructed bandwidth-compressed image consists of an edge map of the scene background, with primary and secondary target windows embedded in the edge map. The bandwidth-compressed images are updated at a basic rate of 1 frame per second, with the high-priority target window updated at 7.5 frames per second. The scene-analysis algorithms used in this system together with the adaptive priority controller are described. Results of simulated 1000:1 bandwidth-compressed images are presented.

  18. Where there's smoke: Cigarette use, social acceptability, and spatial approaches to multilevel modeling.

    PubMed

    O'Connell, Heather A

    2015-09-01

    I contribute to understandings of how context is related to individual outcomes by assessing the added value of combining multilevel and spatial modeling techniques. This methodological approach leads to substantive contributions to the smoking literature, including improved clarity on the central contextual factors and the examination of one manifestation of the social acceptability hypothesis. For this analysis I use restricted-use natality data from the Vital Statistics, and county-level data from the 2005-9 ACS. Critically, the results suggest that spatial considerations are still relevant in a multilevel framework. In addition, I argue that spatial processes help explain the relationships linking racial/ethnic minority concentration to lower overall odds of smoking. PMID:26188587

  19. WHERE THERE’S SMOKE: CIGARETTE USE, SOCIAL ACCEPTABILITY, AND SPATIAL APPROACHES TO MULTILEVEL MODELING

    PubMed Central

    O’Connell, Heather A.

    2015-01-01

    I contribute to understandings of how context is related to individual outcomes by assessing the added value of combining multilevel and spatial modeling techniques. This methodological approach leads to substantive contributions to the smoking literature, including improved clarity on the central contextual factors and the examination of one manifestation of the social acceptability hypothesis. For this analysis I use restricted-use natality data from the Vital Statistics, and county-level data from the 2005–9 ACS. Critically, the results suggest that spatial considerations are still relevant in a multilevel framework. In addition, I argue that spatial processes help explain the relationships linking racial/ethnic minority concentration to lower overall odds of smoking. PMID:26188587

  20. Peer Acceptance in the School Class and Subjective Health Complaints: A Multilevel Approach

    ERIC Educational Resources Information Center

    Almquist, Ylva B.; Modin, Bitte; Augustine, Lilly

    2013-01-01

    Background: Feeling accepted by peers is important for young people's health but few studies have examined the overall degree of acceptance in school and its health consequences. The purpose of the study was to investigate whether health complaints among Swedish students can be attributed to the acceptance climate in their school class even…

  1. Generation of microwaves by mixing two optical frequencies in a nonlinear crystal: a novel approach to high-bandwidth optical mixers.

    PubMed

    Tran, N H; Kachru, R; Gallagher, T F; Watjen, J P; Bjorklund, G C

    1984-04-01

    Optical mixing of waves separated in frequency by many gigahertz can be accomplished by allowing the waves to mix in a nonlinear medium to generate microwave difference frequencies. This basis for high-bandwidth optical mixers is demonstrated by mixing optical frequencies approximately 4 GHz apart of a pulsed dye-laser beam at approximately 660 nm in a LiTaO(3) crystal to produce readily detectable microwave power at approximately 4 GHz. PMID:19721519

  2. ABB: active bandwidth broker

    NASA Astrophysics Data System (ADS)

    Wong, Kason; Law, Eddie

    2001-07-01

    In this paper, we shall discuss a novel design on the policy-based management for the Internet. This design deploys the concept of active networking. As opposed to the traditional network design, active network empowers network node with the ability to manipulate data and program code in packets, and configure the network properties according to the needs of different applications. The policy-based management can control network routers in order to realize end-to-end Quality of Service (QoS), such as differentiated and integrated services, across the Internet. For the moment, the Internet Engineering Task Force (IETF) has defined the framework of the policy-based management. It employs a simple client/server model that uses Common Open Policy Service (COPS) protocol to facilitate policy management and control. Our design of Active Bandwidth Broker (ABB) belongs to an active application. Our goals are to distribute centralized workload of the policy-based management over multiple active nodes in the active networks, introduce mobility of the bandwidth brokers, and allows load sharing to the policy-based management. This results a network-wide intelligent, highly available, and consistent QoS control that allows performance protection for voice, video and Internet business application while reducing costs for growing networks.

  3. Promoting functional foods as acceptable alternatives to doping: potential for information-based social marketing approach

    PubMed Central

    2010-01-01

    Background Substances with performance enhancing properties appear on a continuum, ranging from prohibited performance enhancing drugs (PED) through dietary supplements to functional foods (FF). Anti-doping messages designed to dissuade athletes from using PEDs have been typically based on moralising sport competition and/or employing scare campaigns with focus on the negative consequences. Campaigns offering comparable and acceptable alternatives are nonexistent, nor are athletes helped in finding these for themselves. It is timely that social marketing strategies for anti-doping prevention and intervention incorporate media messages that complement the existing approaches by promoting comparable and acceptable alternatives to doping. To facilitate this process, the aim of this study was to ascertain whether a single exposure knowledge-based information intervention led to increased knowledge and subsequently result in changes in beliefs and automatic associations regarding performance enhancements. Methods In a repeated measure design, 115 male recreational gym users were recruited and provided with a brief information pamphlet on nitrite/nitrate and erythropoietin as a comparison. Measures of knowledge, beliefs and automatic associations were taken before and after the intervention with at least 24 hours between the two assessments. The psychological tests included explicit measures of beliefs and cognitive attitudes toward FF and PED using a self-reported questionnaire and computerised assessments of automatic associations using the modified and shortened version of the Implicit Association Test. Results The information based intervention significantly increased knowledge (p < 0.001), changed explicit beliefs in specific FF (p < 0.001) and shifted the automatic association of FF with health to performance (p < 0.001). Explicitly expressed beliefs and automatic associations appear to be independent. Conclusion Evidence was found that even a single exposure to a

  4. An Integrated Approach for Preservice Teachers' Acceptance and Use of Technology: UTAUT-PST Scale

    ERIC Educational Resources Information Center

    Kabakçi-Yurdakul, Isil; Ursavas, Ömer Faruk; Becit-Isçitürk, Gökçe

    2014-01-01

    Problem Statement: In educational systems, teachers and preservice teachers are the keys to the effective use of technology in the teaching and learning processes. Predicting teachers' technology acceptance and use remains an important issue. Models and theories have been developed to explain and predict technology acceptance. The Unified Theory…

  5. Bandwidth and Noise in Spatiotemporally Modulated Mueller Matrix Polarimeters

    NASA Astrophysics Data System (ADS)

    Vaughn, Israel Jacob

    Polarimetric systems design has seen recent utilization of linear systems theory for system descriptions. Although noise optimal systems have been shown, bandwidth performance has not been addressed in depth generally and is particularly lacking for Mueller matrix (active) polarimetric systems. Bandwidth must be considered in a systematic way for remote sensing polarimetric systems design. The systematic approach facilitates both understanding of fundamental constraints and design of higher bandwidth polarimetric systems. Fundamental bandwidth constraints result in production of polarimetric "artifacts" due to channel crosstalk upon Mueller matrix reconstruction. This dissertation analyzes bandwidth trade-offs in spatio-temporal channeled Mueller matrix polarimetric systems. Bandwidth is directly related to the geometric positioning of channels in the Fourier (channel) space, however channel positioning for polarimetric systems is constrained both physically and by design parameters like domain separability. We present the physical channel constraints and the constraints imposed when the carriers are separable between space and time. Polarimetric systems are also constrained by noise performance, and there is a trade-off between noise performance and bandwidth. I develop cost functions which account for the trade-off between noise and bandwidth for spatio-temporal polarimetric systems. The cost functions allow a systems designer to jointly optimize systems with good bandwidth and noise performance. Optimization is implemented for a candidate spatio-temporal system design, and high temporal bandwidth systems resulting from the optimization are presented. Systematic errors which impact the bandwidth performance and mitigation strategies for these systematic errors are also presented. Finally, a portable imaging Mueller matrix system is built and analyzed based on the theoretical bandwidth analysis and system bandwidth optimization. Temporal bandwidth performance is

  6. Bandwidth-sharing in LHCONE, an analysis of the problem

    NASA Astrophysics Data System (ADS)

    Wildish, T.

    2015-12-01

    to inefficient use of the network. If one user cannot use their quota for some reason, that bandwidth is lost. Likewise, there is no incentive for the user to be efficient within their quota, they have nothing to gain by using less than their allocation. As with CPU farms, some sort of dynamic allocation is more likely to be useful. A promising approach for sharing bandwidth at LHCONE is the ’Progressive Second-Price auction’, where users are given a budget and are required to bid from that budget for the specific resources they want to reserve. The auction allows users to effectively determine among themselves the degree of sharing they are willing to accept based on the priorities of their traffic and their global share, as represented by their total budget. The network then implements those allocations using whatever mix of technologies is appropriate or available. This paper describes how the Progressive Second-Price auction works and how it can be applied to LHCONE. Practical questions are addressed, such as how are budgets set, what strategy should users use to manage their budget, how and how often should the auction be run, and how do we ensure that the goals of fairness and efficiency are met.

  7. Integrated approach to bandwidth reduction and mine detection in shallow water with reduced-dimension image compression and automatic target recognition algorithms

    NASA Astrophysics Data System (ADS)

    Shin, Frances B.; Kil, David H.; Dobeck, Gerald J.

    1997-07-01

    In distributed underwater signal processing for area surveillance and sanitization during regional conflicts, it is often necessary to transmit raw imagery data to a remote processing station for detection-report confirmation and more sophisticated automatic target recognition (ATR) processing. Because of he limited bandwidth available for transmission, image compression is of paramount importance. At the same time, preservation of useful information that contains essential signal attributes is crucial for effective mine detection and classification in shallow water. In this paper, we present an integrated processing strategy that combines image compression and ATR algorithms for superior detection performance while achieving maximal bandwidth reduction. Our reduced-dimension image compression algorithm comprises image-content classification for the subimage-specific transformation, principal component analysis for further dimension reduction, and vector quantization to obtain minimal information state. Next, using an integrated pattern recognition paradigm, our ATR algorithm optimally combines low-dimensional features and an appropriate classifier topology to extract maximum recognition performance from reconstructed images. Instead of assessing performance of the image compression algorithm in terms of commonly used peak signal-to-noise ratio or normalized mean-squared error criteria, we quantify our algorithm performance using a metric that reflects human and operational factors - ATR performance. Our preliminary analysis based on high-frequency sonar real data indicates that we can achieve a compression ratio of up to 57:1 with minimal sacrifice in PD and PFA. Furthermore, we discuss the concept of the classification Cramer-Rao bound in terms of data compression, sufficient statistics, and class separability to quantify the extent to which a classifier approximates the Bayes classifier.

  8. Framework for the analysis of nanotechnologies' impacts and ethical acceptability: basis of an interdisciplinary approach to assessing novel technologies.

    PubMed

    Patenaude, Johane; Legault, Georges-Auguste; Beauvais, Jacques; Bernier, Louise; Béland, Jean-Pierre; Boissy, Patrick; Chenel, Vanessa; Daniel, Charles-Étienne; Genest, Jonathan; Poirier, Marie-Sol; Tapin, Danielle

    2015-04-01

    The genetically manipulated organism (GMO) crisis demonstrated that technological development based solely on the law of the marketplace and State protection against serious risks to health and safety is no longer a warrant of ethical acceptability. In the first part of our paper, we critique the implicitly individualist social-acceptance model for State regulation of technology and recommend an interdisciplinary approach for comprehensive analysis of the impacts and ethical acceptability of technologies. In the second part, we present a framework for the analysis of impacts and acceptability, devised-with the goal of supporting the development of specific nanotechnological applications-by a team of researchers from various disciplines. At the conceptual level, this analytic framework is intended to make explicit those various operations required in preparing a judgement about the acceptability of technologies that have been implicit in the classical analysis of toxicological risk. On a practical level, we present a reflective tool that makes it possible to take into account all the dimensions involved and understand the reasons invoked in determining impacts, assessing them, and arriving at a judgement about acceptability. PMID:24728612

  9. Improved-Bandwidth Transimpedance Amplifier

    NASA Technical Reports Server (NTRS)

    Chapsky, Jacob

    2009-01-01

    The widest available operational amplifier, with the best voltage and current noise characteristics, is considered for transimpedance amplifier (TIA) applications where wide bandwidth is required to handle fast rising input signals (as for time-of-flight measurement cases). The added amplifier inside the TIA feedback loop can be configured to have slightly lower voltage gain than the bandwidth reduction factor.

  10. Estimating Bottleneck Bandwidth using TCP

    NASA Technical Reports Server (NTRS)

    Allman, Mark

    1998-01-01

    Various issues associated with estimating bottleneck bandwidth using TCP are presented in viewgraph form. Specific topics include: 1) Why TCP is wanted to estimate the bottleneck bandwidth; 2) Setting ssthresh to an appropriate value to reduce loss; 3) Possible packet-pair solutions; and 4) Preliminary results: ACTS and the Internet.

  11. An ultra-wide bandwidth-based range/GPS tight integration approach for relative positioning in vehicular ad hoc networks

    NASA Astrophysics Data System (ADS)

    Shen, Feng; Wayn Cheong, Joon; Dempster, Andrew G.

    2015-04-01

    Relative position awareness is a vital premise for the implementation of emerging intelligent transportation systems, such as collision warning. However, commercial global navigation satellite systems (GNSS) receivers do not satisfy the requirements of these applications. Fortunately, cooperative positioning (CP) techniques, through sharing the GNSS measurements between vehicles, can improve the performance of relative positioning in a vehicular ad hoc network (VANET). In this paper, while assuming there are no obstacles between vehicles, a new enhanced tightly coupled CP technique is presented by adding ultra-wide bandwidth (UWB)-based inter-vehicular range measurements. In the proposed CP method, each vehicle fuses the GPS measurements and the inter-vehicular range measurements. Based on analytical and experimental results, in the full GPS coverage environment, the new tight integration CP method outperforms the INS-aided tight CP method, tight CP method, and DGPS by 11%, 15%, and 24%, respectively; in the GPS outage scenario, the performance improvement achieves 60%, 65%, and 73%, respectively.

  12. Determinants of Social Networking Software Acceptance: A Multi-Theoretical Approach

    ERIC Educational Resources Information Center

    Shittu, Ahmed Tajudeen; Madarsha, Kamal Basha; AbduRahman, Nik Suryani Nik; Ahmad, Tunku Badariah Tunku

    2013-01-01

    Understanding reasons why students use social media has become a major preoccupation of researchers in recent time due to the rate of its adoption among the present generation of students. Some of the few study on social media phenomenon employed a single theory as a framework in order to understand the factors that influence the acceptance of it…

  13. Measuring the Moderating Effect of Gender and Age on E-Learning Acceptance in England: A Structural Equation Modeling Approach for an Extended Technology Acceptance Model

    ERIC Educational Resources Information Center

    Tarhini, Ali; Hone, Kate; Liu, Xiaohui

    2014-01-01

    The success of an e-learning intervention depends to a considerable extent on student acceptance and use of the technology. Therefore, it has become imperative for practitioners and policymakers to understand the factors affecting the user acceptance of e-learning systems in order to enhance the students' learning experience. Based on an extended…

  14. Simulator study of minimum acceptable level of longitudinal stability for a representative STOL configuration during landing approach

    NASA Technical Reports Server (NTRS)

    Grantham, W. D.; Deal, P. L.

    1974-01-01

    A fixed-base simulator study was conducted to determine the minimum acceptable level of longitudinal stability for a representative turbofan STOL (short take-off and landing) transport airplane during the landing approach. Real-time digital simulation techniques were used. The computer was programed with equations of motion for six degrees of freedom, and the aerodynamic inputs were based on measured wind-tunnel data. The primary piloting task was an instrument approach to a breakout at a 60-m (200-ft) ceiling.

  15. Ultra-broad bandwidth parametric amplification at degeneracy.

    PubMed

    Limpert, J; Aguergaray, C; Montant, S; Manek-Hönninger, I; Petit, S; Descamps, D; Cormier, E; Salin, F

    2005-09-19

    We report on a novel approach of ultra-broad bandwidth parametric amplification around degeneracy. A bandwidth of up to 400 nm centered around 800 nm is amplified in a BBO crystal by using chirped pump pulses with a bandwitdth as broad as 10 nm. A supercontinuum signal is generated in a microstructured fiber, having to first order a quadratic chirp, which is necessary to ensure temporal overlap of the interacting waves over this broad bandwidth. Furthermore, we discuss the potential of this approach for an octave-spanning parametric amplification. PMID:19498762

  16. Bandwidth characteristics of multimedia data traffic on a local area network

    NASA Technical Reports Server (NTRS)

    Chuang, Shery L.; Doubek, Sharon; Haines, Richard F.

    1993-01-01

    minimal frame rates and/or within seconds of delay, depending on the user's allocated bandwidth. Further research to identify the acceptable delay interval and its impact on human performance is required. Additional studies in network performance using various video compression algorithms and integrated multimedia techniques are needed to determine the optimal design approach for utilizing SSF's data communications system.

  17. Pathway analysis approach for determining acceptable levels of contamination of radionuclides in soil

    SciTech Connect

    Till, J.E.; Moore, R.E.

    1988-09-01

    A methodology for determining acceptable levels for decontamination of soil containing radionuclides at waste sites is described. This methodology calculates the annual radiation dose that an individual receives while living on property that has been decommissioned and decontaminated. Pathways of exposure include direct radiation from ground surfaces, ingestion of contaminated food, inhalation of resuspended radionuclides and drinking contaminated water. Results calculated using this methodology were compared with U.S. Department of Energy (DOE) guidelines for a southeastern U.S. site. There is good agreement between the two methods provided similar assumptions are used.

  18. DECOM: A pathway analysis approach for determining acceptable levels of contamination of radionuclides in soil

    SciTech Connect

    Till, J.E.; Moore, R.E.

    1986-02-28

    The purpose of this report is to describe a method for determining acceptable levels for decontamination of soil containing radionuclides at waste sites located on the Savannah River Plant. This task was achieved through development of a computer program called ''DECOM.'' The DECOM code is written in BASIC, runs on an IBM microcomputer (AT, XT, or compatible), is interactive, and calculates the annual radiation dose that an individual receives while living on property that has been decommissioned and decontaminated. User selected pathways of exposure include direct radiation from ground surface, ingestion of contaminated food, inhalation of resuspended radionuclides, and drinking contaminated water. The program requires a minimum of knowledge in radiological assessment. Although default values have been provided for most parameters, the methodology requires the user to define an acceptable effective dose equivalent that the resident can receive. Other input data required to run the code include the concentration of radionuclides in soil and some site specific parameters relating to the characteristics of the area. 37 refs., 2 figs., 4 tabs.

  19. TESTING INDOOR AIR PRODUCTS: ONE APPROACH TO DEVELOPING WIDELY ACCEPTED PROTOCOLS

    EPA Science Inventory

    The paper describes an approach to developing widely acce ted products for testing indoor air products. [NOTE: Research Triangle Institute (RTI) is a partner in the U.S. Environmental Protection Agency's (EPA's) Environmental Technology Verification (ETV) Program with responsibil...

  20. Integrated Systems-Based Approach for Reaching Acceptable End Points for Groundwater - 13629

    SciTech Connect

    Lee, M. Hope; Wellman, Dawn; Truex, Mike; Freshley, Mark D.; Sorenson, Kent S. Jr.; Wymore, Ryan

    2013-07-01

    The sheer mass and nature of contaminated materials at DOE and DoD sites, makes it impractical to completely restore these sites to pre-disposal conditions. DOE faces long-term challenges, particularly with developing monitoring and end state approaches for clean-up that are protective of the environment, technically based and documented, sustainable, and most importantly cost effective. Integrated systems-based monitoring approaches (e.g., tools for characterization and monitoring, multi-component strategies, geophysical modeling) could provide novel approaches and a framework to (a) define risk-informed endpoints and/or conditions that constitute completion of cleanup and (b) provide the understanding for implementation of advanced scientific approaches to meet cleanup goals. Multi-component strategies which combine site conceptual models, biological, chemical, and physical remediation strategies, as well as iterative review and optimization have proven successful at several DOE sites. Novel tools such as enzyme probes and quantitative PCR for DNA and RNA, and innovative modeling approaches for complex subsurface environments, have been successful at facilitating the reduced operation or shutdown of pump and treat facilities and transition of clean-up activities into monitored natural attenuation remedies. Integrating novel tools with site conceptual models and other lines of evidence to characterize, optimize, and monitor long term remedial approaches for complex contaminant plumes are critical for transitioning active remediation into cost effective, yet technically defensible endpoint strategies. (authors)

  1. Steel Industry Energy Bandwidth Study

    SciTech Connect

    none,

    2004-10-01

    ITP conducted a study on energy use and potential savings, or "bandwidth" study, in major steelmaking processes. Intended to provide a realistic estimate of the potential amount of energy that can be saved in an industrial process, the "bandwidth" refers to the difference between the amount of energy that would be consumed in a process using commercially available technology versus the minimum amount of energy needed to achieve those same results based on the 2nd law of thermodynamics. The Steel Industry Energy Bandwidth Study (PDF 133 KB) also estimates steel industry energy use in the year 2010, and uses that value as a basis for comparison against the minimum requirements. This energy savings opportunity for 2010 will aid focus on longer term R&D.

  2. A Mindfulness-Acceptance-Commitment-Based Approach to Athletic Performance Enhancement: Theoretical Considerations

    ERIC Educational Resources Information Center

    Gardner, Frank L.; Moore, Zella E.

    2004-01-01

    While traditional cognitive-behavioral skills-training-based approaches to athletic performance enhancement posit that negative thoughts and emotions must be controlled, eliminated, or replaced for athlete-clients to perform optimally, recent evidence suggests that efforts to control, eliminate, or suppress these internal states may actually have…

  3. Mining Industry Energy Bandwidth Study

    SciTech Connect

    none,

    2007-07-01

    The Industrial Technologies Program (ITP) relies on analytical studies to identify large energy reduction opportunities in energy-intensive industries and uses these results to guide its R&D portfolio. The energy bandwidth illustrates the total energy-saving opportunity that exists in the industry if the current processes are improved by implementing more energy-efficient practices and by using advanced technologies. This bandwidth analysis report was conducted to assist the ITP Mining R&D program in identifying energy-saving opportunities in coal, metals, and mineral mining. These opportunities were analyzed in key mining processes of blasting, dewatering, drilling, digging, ventilation, materials handling, crushing, grinding, and separations.

  4. 47 CFR 95.633 - Emission bandwidth.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Emission bandwidth. 95.633 Section 95.633... SERVICES Technical Regulations Technical Standards § 95.633 Emission bandwidth. (a) The authorized bandwidth (maximum permissible bandwidth of a transmission) for emission type H1D, J1D, R1D, H3E, J3E or...

  5. 47 CFR 2.202 - Bandwidths.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false Bandwidths. 2.202 Section 2.202 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Emissions § 2.202 Bandwidths. (a) Occupied bandwidth. The frequency bandwidth such that, below its lower and above its...

  6. 47 CFR 2.202 - Bandwidths.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Bandwidths. 2.202 Section 2.202 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Emissions § 2.202 Bandwidths. (a) Occupied bandwidth. The frequency bandwidth such that, below its lower and above its...

  7. 47 CFR 2.202 - Bandwidths.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Bandwidths. 2.202 Section 2.202 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Emissions § 2.202 Bandwidths. (a) Occupied bandwidth. The frequency bandwidth such that, below its lower and above its...

  8. Developing Strategies for Affordable Bandwidth.

    ERIC Educational Resources Information Center

    Educause Quarterly, 2000

    2000-01-01

    Written by Educause's Net@EDU Broadband Pricing Working Group, this article discusses what institutions of higher education can do to develop good partnerships with broadband vendors in order to negotiate affordable pricing for increased bandwidth. Describes problems with the marketplace, examples from a few universities, and points to remember…

  9. Antenna of adjustable bandwidth based on a pentagonal array

    NASA Astrophysics Data System (ADS)

    Tecpoyotl-Torres, M.; Vera-Dimas, J. G.; Cabello Ruiz, R.; García-García, O.; Escobedo-Alatorre, J.; Sanchez-Mondragon, J.; Torres-Cisneros, M.; Varona, J.; Vargas-Bernal, R.

    2011-09-01

    Antenna characteristics are chosen according to the features determined by the systems where they will be used. While some systems require a very narrow bandwidth, others may operate with a much wider bandwidth. Some techniques used for increasing the bandwidth of a given antenna have considered mechanical adjustment of the air layer thickness, with the consequent change on the effective permittivity and performance. Some other systems consider a suitable choice of feeding techniques and impedance matching network. However, approaches for reducing the bandwidth have not received the same level of attention. Narrow bandwidth antennas are of particular interest in security and surveillance systems. In this work we present a technique, based on the design of a pentagonal antenna array, which allows for adjusting the bandwidth in either direction. The array is formed by an inner patch designed at the desired operating frequency of the system and a gap coupled external ring centered at a different frequency (lower or very near the operating frequency), which determines the potential bandwidth increment or decrement. The feed point is located on the inner patch. As a proof-of-concept, this work offers a tuning range that goes from -40% of the center frequency up to +50% of the center operating frequency of the patch antenna. The single patch antenna of this work was designed and simulated at an operating frequency of 4.9 GHz on RT/Duroid 5880.

  10. Automatic High-Bandwidth Calibration and Reconstruction of Arbitrarily Sampled Parallel MRI

    PubMed Central

    Aelterman, Jan; Naeyaert, Maarten; Gutierrez, Shandra; Luong, Hiep; Goossens, Bart; Pižurica, Aleksandra; Philips, Wilfried

    2014-01-01

    Today, many MRI reconstruction techniques exist for undersampled MRI data. Regularization-based techniques inspired by compressed sensing allow for the reconstruction of undersampled data that would lead to an ill-posed reconstruction problem. Parallel imaging enables the reconstruction of MRI images from undersampled multi-coil data that leads to a well-posed reconstruction problem. Autocalibrating pMRI techniques encompass pMRI techniques where no explicit knowledge of the coil sensivities is required. A first purpose of this paper is to derive a novel autocalibration approach for pMRI that allows for the estimation and use of smooth, but high-bandwidth coil profiles instead of a compactly supported kernel. These high-bandwidth models adhere more accurately to the physics of an antenna system. The second purpose of this paper is to demonstrate the feasibility of a parameter-free reconstruction algorithm that combines autocalibrating pMRI and compressed sensing. Therefore, we present several techniques for automatic parameter estimation in MRI reconstruction. Experiments show that a higher reconstruction accuracy can be had using high-bandwidth coil models and that the automatic parameter choices yield an acceptable result. PMID:24915203

  11. A new approach to low-conductivity, environmentally acceptable thermal insulation. Final report

    SciTech Connect

    Buckley, B.; Day, J.; Ferrero-Heredia, M.; Shanklin, E.; Varadarajan, G.; Woodruff, L.

    1996-02-01

    The object of this work was to develop a low-conductivity, economical, environmentally benign insulation. Specific objectives were to develop the following: (1) a very low conductivity use as ``super insulation`` in refrigerators, and (2) a general-purpose insulation for buildings and other applications. The technical goals of this work were to minimize gas phase, solid phase, and radiative conductivity. The novel approach pursued to achieve low gas phase conductivity was to blow foam with a removable gas or vapor, encapsulate the foam panel in a pouch made with a barrier film, and introduce a very low conductivity gas as the insulating gas phase. For super insulation and general-purpose insulation, the gases of choice were xenon and krypton, respectively. To control cost, the gases were present at low pressure, and the insulating panel was encapsulated with an impermeable polymeric film. Solid-phase conductivity was minimized by using low-density, open-cell, polyurethane foam. For super insulation, radiative heat transfer was impeded by placing aluminized Mylar films between relatively transparent 70-mil foam slabs. For general-purpose insulation, it was projected to impede radiative heat transfer by achieving the same very small cell size with open-cell CO{sub 2}-blown foam as is now achieved with closed-cell CO{sub 2}-blown foam.

  12. RFI to CMS: An Approach to Regulatory Acceptance of Site Remediation Technologies

    NASA Technical Reports Server (NTRS)

    Rowland, Martin A.

    2001-01-01

    Lockheed Martin made a smooth transition from RCRA Facility Investigation (RFI) at the National Aeronautics and Space Administrations'(NASA) Michoud Assembly Facility (MA-F) to its Corrective Measures Study (CMS) phase within the RCRA Corrective Action Process. We located trichloroethylene (TCE) contamination that resulted from the manufacture of the Apollo Program Saturn V rocket and the Space Shuttle External Tank, began the cleanup, and identified appropriate technologies for final remedies. This was accomplished by establishing a close working relationship with the state environmental regulatory agency through each step of the process, and resulted in receiving approvals for each of those steps. The agency has designated Lockheed Martin's management of the TCE-contamination at the MAF site as a model for other manufacturing sites in a similar situation. In February 1984, the Louisiana Department of Environmental Quality (LDEQ) issued a compliance order to begin the clean up of groundwater contaminated with TCE. In April 1984 Lockheed Martin began operating a groundwater recovery well to capture the TCE plume. The well not only removes contaminants, but also sustains an inward groundwater hydraulic gradient so that the potential offsite migration of the TCE plume is greatly diminished. This effort was successful, and for the agency to give orders and for a regulated industry to follow them is standard procedure, but this is a passive approach to solving environmental problems. The goal of the company thereafter was to take a leadership, proactive role and guide the MAF contamination clean up to its best conclusion at minimum time and lowest cost to NASA. To accomplish this goal, we have established a positive working relationship with LDEQ, involving them interactively in the implementation of advanced remedial activities at MAF as outlined in the following paragraphs.

  13. A Flight Investigation to Determine the Lateral Oscillatory Damping Acceptable for an Airplane in the Landing Approach

    NASA Technical Reports Server (NTRS)

    McNeill, Walter E.; Vomaske, Richard F.

    1959-01-01

    An F-86E airplane, in which servo actuation of the ailerons and rudder provides artificial variation of the important lateral and directional aerodynamic stability parameters, has been flown by test pilots of the NASA, U.S. Air Force, and one aircraft manufacturer to determine satisfactory and acceptable levels of lateral oscillatory damping in the landing approach. In addition to normal operational use, particular consideration was given to the emergency condition of failure of stability-augmentation equipment. In this study, the pilots' opinions of the airplane dynamic stability and control characteristics in smooth and simulated rough air have been recorded according to a numerical rating scale. The results are presented in the form of boundaries in terms of cycles to damp to half amplitude, 1/C(sub 1/2), or time to damp to half amplitude, 1/T(1/2) and bank-to-sideslip ratio, and are discussed in relation to existing flying-qualities criteria. Though the present results, which were obtained at 170 knots indicated airspeed and 10,000-feet altitude, indicated that increased damping is required with increased bank-to-sideslip ratio (as found in previous work), consideration of the dampers-failed condition indicated a great reduction in the minimum acceptable damping. At moderate values of bank-to-sideslip ratio, effects of lateral-oscillation period on pilot-opinion variation with damping appeared to be taken into account by use of the parameter 1/T(sub 1/2).

  14. High bandwidth deflection readout for atomic force microscopes.

    PubMed

    Steininger, Juergen; Bibl, Matthias; Yoo, Han Woong; Schitter, Georg

    2015-10-01

    This contribution presents the systematic design of a high bandwidth deflection readout mechanism for atomic force microscopes. The widely used optical beam deflection method is revised by adding a focusing lens between the cantilever and the quadrant photodetector (QPD). This allows the utilization of QPDs with a small active area resulting in an increased detection bandwidth due to the reduced junction capacitance. Furthermore the additional lens can compensate a cross talk between a compensating z-movement of the cantilever and the deflection readout. Scaling effects are analyzed to get the optimal spot size for the given geometry of the QPD. The laser power is tuned to maximize the signal to noise ratio without limiting the bandwidth by local saturation effects. The systematic approach results in a measured -3 dB detection bandwidth of 64.5 MHz at a deflection noise density of 62fm/√Hz. PMID:26520960

  15. High bandwidth deflection readout for atomic force microscopes

    NASA Astrophysics Data System (ADS)

    Steininger, Juergen; Bibl, Matthias; Yoo, Han Woong; Schitter, Georg

    2015-10-01

    This contribution presents the systematic design of a high bandwidth deflection readout mechanism for atomic force microscopes. The widely used optical beam deflection method is revised by adding a focusing lens between the cantilever and the quadrant photodetector (QPD). This allows the utilization of QPDs with a small active area resulting in an increased detection bandwidth due to the reduced junction capacitance. Furthermore the additional lens can compensate a cross talk between a compensating z-movement of the cantilever and the deflection readout. Scaling effects are analyzed to get the optimal spot size for the given geometry of the QPD. The laser power is tuned to maximize the signal to noise ratio without limiting the bandwidth by local saturation effects. The systematic approach results in a measured -3 dB detection bandwidth of 64.5 MHz at a deflection noise density of 62 fm / √{ Hz } .

  16. Bandwidth broker architecture for VoIP QoS

    NASA Astrophysics Data System (ADS)

    Kim, Keith; Mouchtaris, Petros; Samtani, Sunil; Talpade, Rajesh; Wong, Larry

    2001-07-01

    We present a scalable architecture for assuring Quality of Service to VoIP applications in an Internet Service Provider's network. This architecture is based on the Differentiated Services and Bandwidth Broker models, and can also be used by other resource-sensitive applications. In this paper, we elaborate on a number of significant issues involved in the design, implementation, deployment and use of the Bandwidth Broker. The Call Agent architecture is used as the VoIP application. We describe the Bandwidth Broker prototype that is used to validate our approach. Our findings suggest that it is feasible to use the Bandwidth Broker architecture for assuring QoS, and a trade-off exists between the granularity of resource requests and call-setup delay.

  17. Mass parasite control as an approach to stimulate community acceptance of environmental sanitation.

    PubMed

    Trainer, E S

    1983-01-01

    worm density. Baseline community surveys are important for information management. 2 basic components of a parasite control program are stool examination and provision of antihelmintics. The choice of which combination of examination and treatment is best for a given program depends on the budget, parasite prevalence, and desired health education impact. Health education begins with the baseline community surveys, where the general dialogue between project and community people can first develop. Specific health education is needed to promote personal and environmental hygiene. Messages can be disseminated to the people by the use of mass media, print materials, and through discussions. These pilot projects have a snowball approach--where a limited set of activities leads to greater expansion. PMID:12312156

  18. Bilateral adrenal cysts and ectopic pancreatic tissue in Beckwith-Wiedemann syndrome: is a conservative approach acceptable?

    PubMed

    Rahmah, R; Yong, J F; Sharifa, N A; Kuhnle, U

    2004-06-01

    Beckwith-Wiedemann syndrome is a common overgrowth syndrome associated with an increased risk of neoplasias which might be explained by the nature and localization of the genetic defect. While malignant tumors are often associated with hemihypertrophy, benign tumors are also found. We report a patient with the typical features of Beckwith-Wiedemann syndrome with two histologically different abdominal tumors, bilateral cystic adrenals and ectopic pancreatic tissue present at birth. In both tumors no malignancy could be detected. Ectopic pancreatic tissue is rarely seen and has been described in Beckwith-Wiedemann syndrome only once. After extirpation of the ectopic pancreatic tissue the cystic adrenals were left in situ since macroscopically no normal adrenal tissue could be identified and separated. Regular ultrasound examinations revealed complete resolution of the cystic adrenals within 24 months. Thus it seems that a conservative approach in selected tumors associated with the Beckwith-Wiedemann syndrome might be acceptable. PMID:15270410

  19. Acceptability of Physician Directed Academic Detailing to Increase Colorectal Cancer Screening: an Application of the RESPECT Approach

    PubMed Central

    Lawson, Gwen; Basch, Corey H.; Zybert, Patricia; Wolf, Randi L.; Basch, Charles E.

    2015-01-01

    Background: In developing effective interventions to increase colorectal cancer (CRC) screening in at risk populations, a necessary first requirement is feasibility. This paper describes how the RESPECT approach to health education guided the conceptualization and implementation of physician-directed academic detailing (AD) to increase practice-wide CRC screening uptake. Methods: Physician-directed AD was one intervention component in a large educational randomized controlled trial to increase CRC screening uptake. Study participants, primarily urban minority, were aged 50 or older, insured for CRC screening with no out-of-pocket expense and out of compliance with current screening recommendations. The trial was conducted in the New York City metropolitan area. Participants identified their primary care physician; 564 individuals were recruited, representing 459 physician practices. Two-thirds of the physician practices were randomized to receive AD. The RESPECT approach, modified for AD, comprises: 1) Rapport, 2) Educate, but don’t overwhelm, 3) Start with physicians where they are, 4) Philosophical orientation based on a humanistic approach to education, 5) Engagement of the physician and his/her office staff, 6) Care and show empathy, and 7) Trust. Feasibility was assessed as rate of AD delivery. Results: The AD was delivered to 283 (92.5%) of the 306 practices assigned to receive it; 222/283 (78.4%) delivered to the doctor. Conclusion: The AD was feasible and acceptable to implement across a range of clinical settings. The RESPECT approach offers a framework for tailoring educational efforts, allowing flexibility, as opposed to strict adherence to a highly structured script or a universal approach. PMID:26634194

  20. Algorithms and Requirements for Measuring Network Bandwidth

    SciTech Connect

    Jin, Guojun

    2002-12-08

    This report unveils new algorithms for actively measuring (not estimating) available bandwidths with very low intrusion, computing cross traffic, thus estimating the physical bandwidth, provides mathematical proof that the algorithms are accurate, and addresses conditions, requirements, and limitations for new and existing algorithms for measuring network bandwidths. The paper also discusses a number of important terminologies and issues for network bandwidth measurement, and introduces a fundamental parameter -Maximum Burst Size that is critical for implementing algorithms based on multiple packets.

  1. Bandwidth Efficient Wireless Digital Modem Developed

    NASA Technical Reports Server (NTRS)

    Kifle, Muli

    1999-01-01

    NASA Lewis Research Center has developed a digital approach for broadcasting highfidelity audio (nearly compact disk (CD) quality sound) in the commercial frequencymodulated (FM) broadcast band. This digital approach provides a means of achieving high data transmission rates with low hardware complexity--including low mass, size, and power consumption. Lewis has completed the design and prototype development of a bandwidth-efficient digital modem (modulator and demodulator) that uses a spectrally efficient modulation scheme: 16-ary rectangular quadrature amplitude modulation, or 16- ary QAM. The digital implementation is based strictly on inexpensive, commercial off-theshelf digital signal processing (DSP) hardware to perform up and down conversions and pulse shaping. The digital modem transmits data at rates up to 76 kilobits per second (kbps), which is almost 3 times faster than standard 28.8-kbps telephone modems. In addition, the modem offers improved power and spectral performance, flexible operation, and low-cost implementation.

  2. Model approach to estimate the probability of accepting a lot of heterogeneously contaminated powdered food using different sampling strategies.

    PubMed

    Valero, Antonio; Pasquali, Frédérique; De Cesare, Alessandra; Manfreda, Gerardo

    2014-08-01

    Current sampling plans assume a random distribution of microorganisms in food. However, food-borne pathogens are estimated to be heterogeneously distributed in powdered foods. This spatial distribution together with very low level of contaminations raises concern of the efficiency of current sampling plans for the detection of food-borne pathogens like Cronobacter and Salmonella in powdered foods such as powdered infant formula or powdered eggs. An alternative approach based on a Poisson distribution of the contaminated part of the lot (Habraken approach) was used in order to evaluate the probability of falsely accepting a contaminated lot of powdered food when different sampling strategies were simulated considering variables such as lot size, sample size, microbial concentration in the contaminated part of the lot and proportion of contaminated lot. The simulated results suggest that a sample size of 100g or more corresponds to the lower number of samples to be tested in comparison with sample sizes of 10 or 1g. Moreover, the number of samples to be tested greatly decrease if the microbial concentration is 1CFU/g instead of 0.1CFU/g or if the proportion of contamination is 0.05 instead of 0.01. Mean contaminations higher than 1CFU/g or proportions higher than 0.05 did not impact on the number of samples. The Habraken approach represents a useful tool for risk management in order to design a fit-for-purpose sampling plan for the detection of low levels of food-borne pathogens in heterogeneously contaminated powdered food. However, it must be outlined that although effective in detecting pathogens, these sampling plans are difficult to be applied since the huge number of samples that needs to be tested. Sampling does not seem an effective measure to control pathogens in powdered food. PMID:24462218

  3. The seven Cs of the high acceptability of home-based VCT: results from a mixed methods approach in Zambia.

    PubMed

    Jürgensen, Marte; Sandøy, Ingvild F; Michelo, Charles; Fylkesnes, Knut; Mwangala, Sheila; Blystad, Astrid

    2013-11-01

    HIV testing and counselling is a critical gateway to prevention and treatment. Yet, coverage remains insufficient, few couples are tested together and gender differences in access exist. We used an embedded mixed methods approach to investigate possible explanations for the high acceptance of home-based voluntary HIV counselling and testing (HB-VCT) in a pair-matched cluster-randomized trial in Zambia. A baseline survey included 1694 individuals in 36 clusters. Adults in 18 intervention clusters were offered HB-VCT by lay counsellors. Standard testing services were available in both trial arms. After the completion of the intervention, a follow-up survey was conducted in all trial clusters. In addition, 21 in-depth interviews and one focus group discussion were conducted with home-based VCT clients in the intervention arm. Informants favoured the convenience, confidentiality and credibility of HB-VCT. Counsellors were perceived as trustworthy owing to their closeness and conduct, and the consent process was experienced as convincing. Couple testing was selected by 70% of cohabiting couples and was experienced as beneficial by both genders. Levels of first-time testing (68% vs. 29%, p < 0.0001) and re-testing (94% vs. 74%, p < 0.0001) were higher in the intervention than in the control arm. Acceptance of HIV testing and counselling is dependent on stigma, trust and gender. The confidentiality of home-based VCT was essential for overcoming stigma-related barriers, and the selection of local counsellors was important to ensure trust in the services. The high level of couple counselling within HB-VCT may contribute to closing the gender gap in HIV testing, and has benefits for both genders and potentially for prevention of HIV transmission. The study demonstrates the feasibility of achieving high test coverage with an opt-in consent approach. The embedded qualitative component confirmed the high satisfaction with HB-VCT reported in the quantitative survey and was

  4. Specification for wide channel bandwidth one-inch video tape

    NASA Technical Reports Server (NTRS)

    Perry, Jimmy L.

    1988-01-01

    Standards and controls are established for the procurement of wide channel bandwidth one inch video magnetic recording tapes for Very Long Base Interferometer (VLBI) system applications. The Magnetic Tape Certification Facility (MTCF) currently maintains three specifications for the Quality Products List (QPL) and acceptance testing of magnetic tapes. NASA-TM-79724 is used for the QPL and acceptance testing of new analog tapes; NASA-TM-80599 is used for QPL and acceptance testing of new digital tapes; and NASA-TM-100702 is used for the QPL and acceptance testing of new IBM/IBM compatible 3480 magnetic tape cartridges. This specification will be used for the QPL and acceptance testing of new wide channel bandwidth one inch video magnetic recording tapes. The one inch video tapes used by the Jet Propulsion Lab., the Deep Space Network and the Haystack Observatory will be covered by this specification. These NASA stations will use the video tapes for their VLBI system applications. The VLBI system is used for the tracking of quasars and the support of interplanetary exploration.

  5. Low bandwidth robust controllers for flight

    NASA Technical Reports Server (NTRS)

    Biezad, Daniel J.; Chou, Hwei-Lan

    1992-01-01

    During the final reporting period (Jun. - Dec. 1992), analyses of the longitudinal and lateral flying qualities were made for propulsive-only flight control (POFC) of a Boeing 720 aircraft model. Performance resulting from compensators developed using Quantitative Feedback Theory (QFT) is documented and analyzed. This report is a first draft of a thesis to be presented by graduate student Hwei-Lan Chou. The final thesis will be presented to NASA when it is completed later this year. The latest landing metrics related to bandwidth criteria and based on the Neal-Smith approach to flying qualities prediction were used in developing performance criteria for the controllers. The compensator designs were tested on the NASA simulator and exhibited adequate performance for piloted flight. There was no significant impact of QFT on performance of the propulsive-only flight controllers in either the longitudinal or lateral modes of flight. This was attributed to the physical limits of thrust available and the engine rate of response, both of whiih severely limited the available bandwidth of the closed-loop system.

  6. Issues and approaches for ensuring effective communication on acceptable daily exposure (ADE) values applied to pharmaceutical cleaning.

    PubMed

    Olson, Michael J; Faria, Ellen C; Hayes, Eileen P; Jolly, Robert A; Barle, Ester Lovsin; Molnar, Lance R; Naumann, Bruce D; Pecquet, Alison M; Shipp, Bryan K; Sussman, Robert G; Weideman, Patricia A

    2016-08-01

    This manuscript centers on communication with key stakeholders of the concepts and program goals involved in the application of health-based pharmaceutical cleaning limits. Implementation of health-based cleaning limits, as distinct from other standards such as 1/1000th of the lowest clinical dose, is a concept recently introduced into regulatory domains. While there is a great deal of technical detail in the written framework underpinning the use of Acceptable Daily Exposures (ADEs) in cleaning (for example ISPE, 2010; Sargent et al., 2013), little is available to explain how to practically create a program which meets regulatory needs while also fulfilling good manufacturing practice (GMP) and other expectations. The lack of a harmonized approach for program implementation and communication across stakeholders can ultimately foster inappropriate application of these concepts. Thus, this period in time (2014-2017) could be considered transitional with respect to influencing best practice related to establishing health-based cleaning limits. Suggestions offered in this manuscript are intended to encourage full and accurate communication regarding both scientific and administrative elements of health-based ADE values used in pharmaceutical cleaning practice. This is a large and complex effort that requires: 1) clearly explaining key terms and definitions, 2) identification of stakeholders, 3) assessment of stakeholders' subject matter knowledge, 4) formulation of key messages fit to stakeholder needs, 5) identification of effective and timely means for communication, and 6) allocation of time, energy, and motivation for initiating and carrying through with communications. PMID:27233923

  7. A single reflection approach to HCPV: Very high concentration ratio and wide acceptance angles using low cost materials

    NASA Astrophysics Data System (ADS)

    De Nardis, Davide

    2012-10-01

    The Italian engineering company Becar (Beghelli SpA group) presents its latest HCPV module currently sold under the brand name "Life Tree". The module is characterized by an efficiency of 26% that is in line with systems having higher complexity. The high efficiency and flexibility of the system are reached thanks to the single reflection scheme of the optical system. The module characterized by high acceptance angles comprises a metalized plastic primary reflector and a secondary optical element. The latter being a crucial technical feature of the Becar's system. This secondary optic element has been developed and manufactured by the German group Evonik Industries, which markets the product under the trade name SAVOSIL(TM). This technology, compared to other optics available in the market, offer high transparency in the whole solar spectrum and it is manufactured with an innovative sol-gel process that guarantees a precision in the micron range, at a fraction of the other approaches cost . Those two important features boost the light harvesting power of the Beghelli's systems. The article shows also the results of extensive in-field tests carried out to confirm reliability, performance and easy maintenance of the system.

  8. Bandwidth requirements for fine resolution squinted SAR

    SciTech Connect

    DOERRY,ARMIN W.

    2000-03-01

    The conventional rule-of-thumb for Synthetic Aperture Radar is that an RF bandwidth of c/(2{rho}{sub r}) is required to image a scene at the desired slant-range resolution {rho}{sub r}, and perhaps a little more to account for window functions and sidelobe control. This formulation is based on the notion that the total bandwidth required is the same bandwidth that is required for a single pulse. What is neglected is that efficient processing of an entire synthetic aperture of pulses will often require different frequency content for each of the different pulses that makeup a synthetic aperture. Consequently, the total RF bandwidth required of a Synthetic Aperture Radar may then be substantially wider than the bandwidth of any single pulse. The actual RF bandwidth required depends strongly on flight geometry, owing to the desire for a radar to maintain a constant projection of the Fourier space collection surface onto the {omega}{sub y} axis. Long apertures required for fine azimuth resolution, and severe squint angles with steep depression angles may require total RF bandwidths well beyond the minimum bandwidth required of any single transmitted pulse, perhaps even by a factor of two or more. Accounting for this is crucial to designing efficient versatile high-performance imaging radars. This paper addresses how a data set conducive to efficient processing might increase the total RF bandwidth, and presents examples of how a fixed RF bandwidth might then limit SAR geometries.

  9. Smart Sand—a wide bandwidth vibration energy harvesting platform

    NASA Astrophysics Data System (ADS)

    Marinkovic, Bozidar; Koser, Hur

    2009-03-01

    We propose a concept for true wide bandwidth vibration energy harvesting. Our approach exploits nonlinear stretching of fixed-fixed beams in an off-resonance mode, effectively expanding the operational frequency range well beyond the narrow bandwidth of linear resonators. Our initial prototype demonstrates operation between 160-400 Hz, without the need for frequency tuning. A simple dynamic model shows good agreement with measurements. Optimized device geometry will allow for even lower frequency operation (starting at 60 Hz) at strain levels above 1e-3 (ideal for piezoelectric transduction).

  10. An octave-bandwidth negligible-loss radiofrequency metamaterial.

    PubMed

    Lier, Erik; Werner, Douglas H; Scarborough, Clinton P; Wu, Qi; Bossard, Jeremy A

    2011-03-01

    Metamaterials provide an unprecedented ability to manipulate electromagnetic waves and are an enabling technology for new devices ranging from flat lenses that focus light beyond the diffraction limit to coatings capable of cloaking an object. Nevertheless, narrow bandwidths and high intrinsic losses arising from the resonant properties of metamaterials have raised doubts about their usefulness. New design approaches seek to turn the perceived disadvantages of dispersion into assets that enhance a device's performance. Here we employ dispersion engineering of metamaterial properties to enable specific device performance over usable bandwidths. In particular, we design metamaterials that considerably improve conventional horn antennas over greater than an octave bandwidth with negligible loss and advance the state of the art in the process. Fabrication and measurement of a metahorn confirm its broadband, low-loss performance. This example illustrates the power of clever implementation combined with dispersion engineering to bring metamaterials into their full potential for revolutionizing practical devices. PMID:21278741

  11. An octave-bandwidth negligible-loss radiofrequency metamaterial

    NASA Astrophysics Data System (ADS)

    Lier, Erik; Werner, Douglas H.; Scarborough, Clinton P.; Wu, Qi; Bossard, Jeremy A.

    2011-03-01

    Metamaterials provide an unprecedented ability to manipulate electromagnetic waves and are an enabling technology for new devices ranging from flat lenses that focus light beyond the diffraction limit to coatings capable of cloaking an object. Nevertheless, narrow bandwidths and high intrinsic losses arising from the resonant properties of metamaterials have raised doubts about their usefulness. New design approaches seek to turn the perceived disadvantages of dispersion into assets that enhance a device’s performance. Here we employ dispersion engineering of metamaterial properties to enable specific device performance over usable bandwidths. In particular, we design metamaterials that considerably improve conventional horn antennas over greater than an octave bandwidth with negligible loss and advance the state of the art in the process. Fabrication and measurement of a metahorn confirm its broadband, low-loss performance. This example illustrates the power of clever implementation combined with dispersion engineering to bring metamaterials into their full potential for revolutionizing practical devices.

  12. Rehabilitation Counseling for Athletes Prior to Retirement: A Preventative Approach Using Self-Acceptance To Enhance Performance before and after Retirement.

    ERIC Educational Resources Information Center

    Mills, Brett D.

    This paper suggests that collegiate and professional athletes preparing to retire should be provided with preretirement and postretirement rehabilitation counseling. The counseling should involve a preventative approach centered around self-acceptance, to enhance the athlete's performance before and after retirement. The development of…

  13. Optimal dynamic bandwidth allocation for complex networks

    NASA Astrophysics Data System (ADS)

    Jiang, Zhong-Yuan; Liang, Man-Gui; Li, Qian; Guo, Dong-Chao

    2013-03-01

    Traffic capacity of one network strongly depends on the link’s bandwidth allocation strategy. In previous bandwidth allocation mechanisms, once one link’s bandwidth is allocated, it will be fixed throughout the overall traffic transmission process. However, the traffic load of every link changes from time to time. In this paper, with finite total bandwidth resource of the network, we propose to dynamically allocate the total bandwidth resource in which each link’s bandwidth is proportional to the queue length of the output buffer of the link per time step. With plenty of data packets in the network, the traffic handling ability of all links of the network achieves full utilization. The theoretical analysis and the extensive simulation results on complex networks are consistent. This work is valuable for network service providers to improve network performance or to do reasonable network design efficiently.

  14. Bandwidth controller for phase-locked-loop

    NASA Technical Reports Server (NTRS)

    Brockman, Milton H. (Inventor)

    1992-01-01

    A phase locked loop utilizing digital techniques to control the closed loop bandwidth of the RF carrier phase locked loop in a receiver provides high sensitivity and a wide dynamic range for signal reception. After analog to digital conversion, a digital phase locked loop bandwidth controller provides phase error detection with automatic RF carrier closed loop tracking bandwidth control to accommodate several modes of transmission.

  15. Estimation of floods with long return period using continuous simulation within the framework of the limits of acceptability approach

    NASA Astrophysics Data System (ADS)

    Beven, K.; Blazkova, S.

    2009-04-01

    The estimation of flood frequency by continuous simulation provides an alternative method to direct statistical estimation for catchments where there are limited historical records of flood peaks. We are presenting the extended GLUE multiple limits of acceptability calibration strategy in which models are treated as hypotheses about system response, to be rejected if the predictions fall outside of the limits of acceptability. Flood frequency predictions on the Skalka catchment in the Czech Republic (672 km2, range of altitudes from 460 to 1041 m a.s.l.), are compared against summary information of rainfall characteristics, the flow duration curve, and the frequency characteristics of flood discharges and snow water equivalent. Limits of acceptability have been defined, prior to running the Monte Carlo model realisations. Since we have identified only 39 behavioural models we have relaxed the limits of acceptability using a procedure of scoring deviations relative to the limits, to identify the minimum extension across all criteria (together 114 criteria) to obtain a sample of 4192 parameter sets that were accepted as potentially useful in prediction. Long term simulations of 10000 years for retained models were used to obtain uncertain estimates of the 1000 year peak required for the assessment of dam safety at the catchment outlet. We also demonstrate the effect of different input realisations on acceptability. Taking just one of the behavioural parameter sets and generating 10,000 input sequences of the same length as the observed flood series results in a range of critical values for acceptability across a range of evaluation criteria.

  16. Multiple-bandwidth photoacoustic tomography.

    PubMed

    Ku, Geng; Wang, Xueding; Stoica, George; Wang, Lihong V

    2004-04-01

    Photoacoustic tomography, also referred to as optoacoustic tomography, employs short laser pulses to generate ultrasonic waves in biological tissues. The reconstructed images can be characterized by the convolution of the structure of samples, the laser pulse and the impulse response of the ultrasonic transducer used for detection. Although the laser-induced ultrasonic waves cover a wide spectral range, a single transducer can receive only part of the spectrum because of its limited bandwidth. To systematically analyse this problem, we constructed a photoacoustic tomographic system that uses multiple ultrasonic transducers simultaneously, each at a different central frequency. The photoacoustic images associated with the different transducers were compared and analysed. The system was tested by imaging both mouse brains and phantom samples. The vascular vessels in the brain were revealed by all of the transducers, but the image resolutions differed. The higher frequency detectors provided better image resolution while the lower frequency detectors delineated the major structural traits with a higher signal-noise ratio. PMID:15128208

  17. Acceptability of a web-based community reinforcement approach for substance use disorders with treatment-seeking American Indians/Alaska Natives.

    PubMed

    Campbell, Aimee N C; Turrigiano, Eva; Moore, Michelle; Miele, Gloria M; Rieckmann, Traci; Hu, Mei-Chen; Kropp, Frankie; Ringor-Carty, Roz; Nunes, Edward V

    2015-05-01

    Longstanding disparities in substance use disorders and treatment access exist among American Indians/Alaska Natives (AI/AN). Computerized, web-delivered interventions have potential to increase access to quality treatment and improve patient outcomes. Prior research supports the efficacy of a web-based version [therapeutic education system (TES)] of the community reinforcement approach to improve outcomes among outpatients in substance abuse treatment; however, TES has not been tested among AI/AN. The results from this mixed method acceptability study among a diverse sample of urban AI/AN (N = 40) show that TES was acceptable across seven indices (range 7.8-9.4 on 0-10 scales with 10 indicating highest acceptability). Qualitative interviews suggest adaptation specific to AI/AN culture could improve adoption. Additional efforts to adapt TES and conduct a larger effectiveness study are warranted. PMID:25022913

  18. Directing Traffic: Managing Internet Bandwidth Fairly

    ERIC Educational Resources Information Center

    Paine, Thomas A.; Griggs, Tyler J.

    2008-01-01

    Educational institutions today face budgetary restraints and scarce resources, complicating the decision of how to allot bandwidth for campus network users. Additionally, campus concerns over peer-to-peer networking (specifically outbound Internet traffic) have increased because of bandwidth and copyright issues. In this article, the authors…

  19. 47 CFR 2.202 - Bandwidths.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... quality desired Speech and music, M=4000, Bandwidth: 8000 Hz= 8 kHz 8K00A3E Sound broadcasting, single... desired Speech and music, M=4000, Bandwidth: 4000 Hz= 4 kHz 4K00R3E Sound broadcasting, single-sideband, suppressed carrier Bn=M−lowest modulation frequency Speech and music, M=4500, lowest modulation...

  20. Energy Bandwidth for Petroleum Refining Processes

    SciTech Connect

    none,

    2006-10-01

    The petroleum refining energy bandwidth report analyzes the most energy-intensive unit operations used in U.S. refineries: crude oil distillation, fluid catalytic cracking, catalytic hydrotreating, catalytic reforming, and alkylation. The "bandwidth" provides a snapshot of the energy losses that can potentially be recovered through best practices and technology R&D.

  1. 47 CFR 101.109 - Bandwidth.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Bandwidth. 101.109 Section 101.109 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.109 Bandwidth. Link to an amendment published at 76 FR 59572, Sept....

  2. 47 CFR 101.109 - Bandwidth.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Bandwidth. 101.109 Section 101.109 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.109 Bandwidth. (a) Each authorization issued pursuant to these...

  3. Bandwidth enhancement of dielectric resonator antennas

    NASA Technical Reports Server (NTRS)

    Lee, Richard Q.; Simons, Rainee N.

    1993-01-01

    An experimental investigation of bandwidth enhancement of dielectric resonator antennas (DRA) using parasitic elements is reported. Substantial bandwidth enhancement for the HE(sub 11delta) mode of the stacked geometry and for the HE(sub 13delta) mode of the coplanar collinear geometry was demonstrated. Excellent radiation patterns for the HE(sub 11delta) mode were also recorded.

  4. Being Mindful about the Assessment of Culture: A Cultural Analysis of Culturally Adapted Acceptance-Based Behavior Therapy Approaches

    ERIC Educational Resources Information Center

    La Roche, Martin; Lustig, Kara

    2013-01-01

    In this article we review a wide range of cultural adaptations of acceptance-based behavior therapies (ABBT) from a cultural perspective. Consistent with the cultural match model, we argue that psychotherapeutic cultural adaptations are more effective as the cultural characteristics of patients are matched to the cultural characteristics of the…

  5. Tunable-Bandwidth Filter System

    NASA Technical Reports Server (NTRS)

    Bailey, John W.

    2004-01-01

    A tunable-bandwidth filter system (TBFS), now undergoing development, is intended to be part of a remote sensing multispectral imaging system that will operate in the visible and near infrared spectral region (wavelengths from 400 to 900 nm). Attributes of the TBFS include rapid tunability of the pass band over a wide wavelength range and high transmission efficiency. The TBFS is based on a unique integration of two pairs of broadband Raman reflection holographic filters with two rotating spherical lenses. In experiments, a prototype of the TBFS, was shown to be capable of spectral sampling of images in the visible range over a 200 nm spectral range with a spectral resolution of 30 nm. The figure depicts the optical layout of a prototype of the TBFS as part of a laboratory multispectral imaging system for the spectral sampling of color test images in two orthogonal polarizations. Each pair of broadband Raman reflection holographic filters is mounted at an equatorial plane between two halves of a spherical lens. The two filters in each pair are characterized by steep spectral slopes (equivalently, narrow spectral edges), no ripple or side lobes in their pass bands, and a few nanometers of non-overlapping wavelength range between their pass bands. Each spherical lens and thus the filter pair within it is rotated in order to rapidly tune its pass band. The rotations of are effected by electronically controlled, programmable, high-precision rotation stages. The rotations are coordinated by electronic circuits operating under overall supervision of a personal computer in order to obtain the desired variation of the overall pass bands with time. Embedding the filters inside the spherical lenses increases the range of the hologram incidence angles, making it possible to continuously tune the pass and stop bands of the filters over a wider wavelength range. In addition, each spherical lens also serves as part of the imaging optics: The telephoto lens focuses incoming light

  6. Tunable-Bandwidth Filter System

    NASA Technical Reports Server (NTRS)

    Aye, Tin; Yu, Kevin; Dimov, Fedor; Savant, Gajendra

    2006-01-01

    A tunable-bandwidth filter system (TBFS), now undergoing development, is intended to be part of a remote-sensing multispectral imaging system that will operate in the visible and near infrared spectral region (wavelengths from 400 to 900 nm). Attributes of the TBFS include rapid tunability of the pass band over a wide wavelength range and high transmission efficiency. The TBFS is based on a unique integration of two pairs of broadband Raman reflection holographic filters with two rotating spherical lenses. In experiments, a prototype of the TBFS was shown to be capable of spectral sampling of images in the visible range over a 200-nm spectral range with a spectral resolution of .30 nm. The figure depicts the optical layout of a prototype of the TBFS as part of a laboratory multispectral imaging system for the spectral sampling of color test images in two orthogonal polarizations. Each pair of broadband Raman reflection holographic filters is mounted at an equatorial plane between two halves of a spherical lens. The two filters in each pair are characterized by steep spectral slopes (equivalently, narrow spectral edges), no ripple or side lobes in their pass bands, and a few nanometers of non-overlapping wavelength range between their pass bands. Each spherical lens and thus the filter pair within it is rotated in order to rapidly tune its pass band. The rotations of the lenses are effected by electronically controlled, programmable, high-precision rotation stages. The rotations are coordinated by electronic circuits operating under overall supervision of a personal computer in order to obtain the desired variation of the overall pass bands with time. Embedding the filters inside the spherical lenses increases the range of the hologram incidence angles, making it possible to continuously tune the pass and stop bands of the filters over a wider wavelength range. In addition, each spherical lens also serves as part of the imaging optics: The telephoto lens focuses

  7. Effective Communication and File-I/O Bandwidth Benchmarks

    SciTech Connect

    Koniges, A E; Rabenseifner, R

    2001-05-02

    We describe the design and MPI implementation of two benchmarks created to characterize the balanced system performance of high-performance clusters and supercomputers: b{_}eff, the communication-specific benchmark examines the parallel message passing performance of a system, and b{_}eff{_}io, which characterizes the effective 1/0 bandwidth. Both benchmarks have two goals: (a) to get a detailed insight into the Performance strengths and weaknesses of different parallel communication and I/O patterns, and based on this, (b) to obtain a single bandwidth number that characterizes the average performance of the system namely communication and 1/0 bandwidth. Both benchmarks use a time driven approach and loop over a variety of communication and access patterns to characterize a system in an automated fashion. Results of the two benchmarks are given for several systems including IBM SPs, Cray T3E, NEC SX-5, and Hitachi SR 8000. After a redesign of b{_}eff{_}io, I/O bandwidth results for several compute partition sizes are achieved in an appropriate time for rapid benchmarking.

  8. U.A.R.: influential factors in the acceptance of birth control and the consequential approaches to family planning.

    PubMed

    Rzepnicki, T; Diller, C

    1973-01-01

    A number of factors have retarded the acceptance of birth control methods among peasant communities in Egypt: 1) the religious world-view of the peasant discourages him from interfering with the natural process of procreation; 2) the large family is important socially and economically in peasant society for strength and security and for the distribution of labor; 3) the status of a married woman depends to a great extent on the number of children, particularly the number of sons, she bears; and 4) in the Egyptian village, the midwife discourages the use of contraception. Acceptance and utilization of birth control methods in Egypt are directly proportionate to the level of education of the individual. The better the economic status of the family, the smaller the family is likely to be. Demographically, the closer a family lives to Cairo, the more likely it is that birth control techniques are being used. Egyptian family planning programs which take into consideration the difficulties of spreading the acceptance and use of contraceptives in traditional societies are discussed. PMID:12333533

  9. A bandwidth enhancement method for microstrip antennas

    NASA Astrophysics Data System (ADS)

    Katehi, Pisti B.; Alexopoulos, Nicolaos G.; Hsia, I. Y.

    1987-01-01

    Bandwidth enhancement methods for electromagnetically coupled microstrip dipoles are discussed. It is demonstrated that if parasitic metallic strips are incorporated in the structure either co-planar and parallel to the embedded microstrip transmission line open end, or between the transmission line and the microstrip dipole, then substantial bandwidth enhancement results. Experimental verification of this model is introduced for a bandwidth definition based on the frequency range which satisfies a voltage standing-wave ratio of less than 2 criterion. The theoretical model which accounts for radiation from the microstrip dipole, the parasitics, and the transmission line is verified.

  10. A dynamic bandwidth allocation scheme for EPON

    NASA Astrophysics Data System (ADS)

    Li, Xiuyuan; Wu, Xiaojuan; Ma, Maode; Li, Wenming; Zhang, Yuanyuan

    2008-11-01

    This paper analyses current bandwidth schemes and proposes a novel dynamic bandwidth allocation scheme for EPON. According the scheme, we define four kinds of multimedia services such as Unsolicited Request Service (URS), Realtime Service (rt-S), Non-Real-time Service (nrt-S) and Best Effort (BE). Different kinds of services have different Quality of Service (QoS) requirements. Our scheme considers the diverse QoS request, e.g., delay for rt-S, throughput for nrt-S and fairness for BE. The simulation results show this novel scheme can ensure the quality of service (QoS) and improve bandwidth utilization.

  11. Sonar feature-based bandwidth compression

    NASA Astrophysics Data System (ADS)

    Saghri, John A.; Tescher, Andrew G.

    1992-07-01

    A sonar bandwidth compression (BWC) technique which, unlike conventional methods, adaptively varies the coding resolution in the compression process based on a priori information is described. This novel approach yields a robust compression system whose performance exceeds the conventional methods by factors of 2-to-1 and 1.5-to-1 for display- formatted and time series sonar data, respectively. The data is first analyzed by a feature extraction routine to determine those pixels of the image that collectively comprise intelligence-bearing signal features. The data is then split into a foreground image which contains the extracted source characteristic and a larger background image which is the remainder. Since the background image is highly textured, it suffices to code only the local statistics rather than the actual pixels themselves. This results in a substantial reduction of the bit rate required to code the background image. The feature-based compression algorithm developed for sonar imagery data is also extended to the sonar time series data via a novel approach involving an initial one-dimensional DCT transformation of the time series data before the actual compression process. The unique advantage of this approach is that the coding is done in an alternative two-dimensional image domain where, unlike the original time domain, it is possible to observe, differentiate, and prioritize essential features of data in the compression process. The feature-based BWC developed for sonar data is potentially very useful for applications involving highly textured imagery. Two such applications are synthetic aperture radar and ultrasound medical imaging.

  12. Same-Gender and Cross-Gender Peer Acceptance and Peer Rejection and Their Relation to Bullying and Helping among Preadolescents: Comparing Predictions from Gender-Homophily and Goal-Framing Approaches

    ERIC Educational Resources Information Center

    Dijkstra, Jan Kornelis; Lindenberg, Siegwart; Veenstra, Rene

    2007-01-01

    The relation between bullying and helping and same-gender and cross-gender peer acceptance and peer rejection was examined in a sample of preadolescents aged 11 and 12 years (N=1,065). The authors tested predictions from a gender-homophily approach vs. predictions from a goal-framing approach in which acceptance and rejection are seen as being…

  13. Reduced bandwidth video for remote vehicle operations

    SciTech Connect

    Noell, T.E.; DePiero, F.W.

    1993-08-01

    Oak Ridge National Laboratory staff have developed a video compression system for low-bandwidth remote operations. The objective is to provide real-time video at data rates comparable to available tactical radio links, typically 16 to 64 thousand bits per second (kbps), while maintaining sufficient quality to achieve mission objectives. The system supports both continuous lossy transmission of black and white (gray scale) video for remote driving and progressive lossless transmission of black and white images for remote automatic target acquisition. The average data rate of the resulting bit stream is 64 kbps. This system has been demonstrated to provide video of sufficient quality to allow remote driving of a High-Mobility Multipurpose Wheeled Vehicle at speeds up to 15 mph (24.1 kph) on a moguled dirt track. The nominal driving configuration provides a frame rate of 4 Hz, a compression per frame of 125:1, and a resulting latency of {approximately}1s. This paper reviews the system approach and implementation, and further describes some of our experiences when using the system to support remote driving.

  14. High bandwidth control of precision motion instrumentation

    NASA Astrophysics Data System (ADS)

    Bristow, Douglas A.; Dong, Jingyan; Alleyne, Andrew G.; Ferreira, Placid; Salapaka, Srinivas

    2008-10-01

    This article presents a high-bandwidth control design suitable for precision motion instrumentation. Iterative learning control (ILC), a feedforward technique that uses previous iterations of the desired trajectory, is used to leverage the repetition that occurs in many tasks, such as raster scanning in microscopy. Two ILC designs are presented. The first design uses the motion system dynamic model to maximize bandwidth. The second design uses a time-varying bandwidth that is particularly useful for nonsmooth trajectories such as raster scanning. Both designs are applied to a multiaxis piezoelectric-actuated flexure system and evaluated on a nonsmooth trajectory. The ILC designs demonstrate significant bandwidth and precision improvements over the feedback controller, and the ability to achieve precision motion control at frequencies higher than multiple system resonances.

  15. The minimum bandwidths of auroral kilometric radiation

    NASA Technical Reports Server (NTRS)

    Baumback, M. M.; Calvert, W.

    1987-01-01

    The bandwidths of the discrete spectral components of the auroral kilometric radiation can sometimes be as narrow as 5 Hz. Since this would imply an apparent source thickness of substantially less than the wavelength, it is inconsistent with the previous explanation for such discrete components based simply upon vertical localization of a cyclotron source. Instead, such narrow bandwidths can only be explained by radio lasing.

  16. A Hybrid OFDM-TDM Architecture with Decentralized Dynamic Bandwidth Allocation for PONs

    PubMed Central

    Cevik, Taner

    2013-01-01

    One of the major challenges of passive optical networks is to achieve a fair arbitration mechanism that will prevent possible collisions from occurring at the upstream channel when multiple users attempt to access the common fiber at the same time. Therefore, in this study we mainly focus on fair bandwidth allocation among users, and present a hybrid Orthogonal Frequency Division Multiplexed/Time Division Multiplexed architecture with a dynamic bandwidth allocation scheme that provides satisfying service qualities to the users depending on their varying bandwidth requirements. Unnecessary delays in centralized schemes occurring during bandwidth assignment stage are eliminated by utilizing a decentralized approach. Instead of sending bandwidth demands to the optical line terminal (OLT) which is the only competent authority, each optical network unit (ONU) runs the same bandwidth demand determination algorithm. ONUs inform each other via signaling channel about the status of their queues. This information is fed to the bandwidth determination algorithm which is run by each ONU in a distributed manner. Furthermore, Light Load Penalty, which is a phenomenon in optical communications, is mitigated by limiting the amount of bandwidth that an ONU can demand. PMID:24194684

  17. A hybrid OFDM-TDM architecture with decentralized dynamic bandwidth allocation for PONs.

    PubMed

    Cevik, Taner

    2013-01-01

    One of the major challenges of passive optical networks is to achieve a fair arbitration mechanism that will prevent possible collisions from occurring at the upstream channel when multiple users attempt to access the common fiber at the same time. Therefore, in this study we mainly focus on fair bandwidth allocation among users, and present a hybrid Orthogonal Frequency Division Multiplexed/Time Division Multiplexed architecture with a dynamic bandwidth allocation scheme that provides satisfying service qualities to the users depending on their varying bandwidth requirements. Unnecessary delays in centralized schemes occurring during bandwidth assignment stage are eliminated by utilizing a decentralized approach. Instead of sending bandwidth demands to the optical line terminal (OLT) which is the only competent authority, each optical network unit (ONU) runs the same bandwidth demand determination algorithm. ONUs inform each other via signaling channel about the status of their queues. This information is fed to the bandwidth determination algorithm which is run by each ONU in a distributed manner. Furthermore, Light Load Penalty, which is a phenomenon in optical communications, is mitigated by limiting the amount of bandwidth that an ONU can demand. PMID:24194684

  18. Maximizing acceptability and usefulness of an automated telephone intervention: Lessons from a developmental mixed-methods approach.

    PubMed

    Schneider, Jennifer; Waterbury, Amy; Feldstein, Adrianne; Donovan, Jerena; Vollmer, William M; Dubanoski, Joan; Clark, Shelley; Rand, Cynthia

    2011-03-01

    The objective was to describe the utility of mixed methods to inform the development of an automated telephone intervention to improve patients' compliance with asthma medication. As part of intervention development for a larger trial, we conducted 15 focus groups (n = 53) to design and develop calls, and to identify factors influencing intervention acceptability and usefulness. We piloted four call types and interviewed 64 participants to further improve call content and receptivity to the intervention. Feedback led to several changes to the intervention scripts and eventual calls, and an initial pilot led us to drop one of the calls. During the pilot, we reached 43 percent of target participants; 74 percent of those stayed on the call until it ended. This process provided key insights about automated calls, and may have broader applicability for the development of automated interventions designed to help patients manage a variety of chronic conditions. PMID:25133772

  19. Quantum gates with optimal bandwidth in noisy environments

    NASA Astrophysics Data System (ADS)

    Low, Guang Hao; Theodore, Yoder; Chuang, Isaac

    The traditional approach of open-loop quantum error correction suppresses certain systematic imperfections ɛ in quantum control to higher orders ɛ  (L) by a well-designed sequence of L imperfect quantum gates. However, this philosophy of maximal flatness leads to an ɛ-bandwidth that scales poorly with length and a residual that is easily overwhelmed by unaccounted sources of noise. We advance the paradigm of equiripple compensated gates that directly optimize for bandwidth given the limitations imposed by noise of magnitude δ, leading to dramatically improved performance. Where ɛ represent amplitude errors, we provide a formalism that generalizes both approaches and is effective at finding such gates. With it, we provide in closed-form the phase angles for an optimal family of population inversion gates with an ɛ -bandwidth of  (logδ-1/L) - a quadratic improvement over optimal maximally flat variants. We also construct optimal NOT gates and discuss extensions to other gates and error models.

  20. Bandwidth and power efficient modulation and coding development

    NASA Astrophysics Data System (ADS)

    Monte, P. A.; Hoeber, C. F.; Tanner, R. Michael

    This paper describes modulation and forward error correction concepts which can be used to increase the bandwidth efficiency of satellite communications links without sacrificing power efficiency. A spacecraft demodulator/decoder is being developed which advances the technology for the next generation of digital communication satellites. This demodulator/decoder is intended for TDMA applications requiring high total data rates composed of many low data rate users. Low TDMA overhead is obtained with a unique approach for achieving fast acquisition. High spectrum efficiency is obtained through the use of a bandwidth efficient coding system, and the design addresses high interference levels associated with spectrum reuse. The implementation of this demodulator and associated FEC decoder employs high speed digital processing in conjunction with parallel pipeline architecture which lends itself to digital LSI fabrication, giving the potential for a compact, power efficient, and highly reliable system appropriate for satellite applications.

  1. The Added-Value of Using Participatory Approaches to Assess the Acceptability of Surveillance Systems: The Case of Bovine Tuberculosis in Belgium

    PubMed Central

    Calba, Clémentine; Goutard, Flavie Luce; Vanholme, Luc; Antoine-Moussiaux, Nicolas; Hendrikx, Pascal; Saegerman, Claude

    2016-01-01

    Context and Objective Bovine tuberculosis (bTB) surveillance in Belgium is essential to maintain the officially free status and to preserve animal and public health. An evaluation of the system is thus needed to ascertain the surveillance provides a precise description of the current situation in the country. The evaluation should assess stakeholders’ perceptions and expectations about the system due to the fact that the acceptability has an influence on the levels of sensitivity and timeliness of the surveillance system. The objective of the study was to assess the acceptability of the bTB surveillance in Belgium, using participatory tools and the OASIS flash tool (‘analysis tool for surveillance systems’). Methods For the participatory process, focus group discussions and individual interviews were implemented with representatives involved with the system, both from cattle and wildlife part of the surveillance. Three main tools were used: (i) relational diagrams associated with smileys, (ii) flow diagrams associated with proportional piling, and (iii) impact diagrams associated with proportional piling. A total of six criteria were assessed, among which five were scored on a scale from -1 to +1. For the OASIS flash tool, one full day meeting with representatives from stakeholders involved with the surveillance was organised. A total of 19 criteria linked to acceptability were scored on a scale from 0 to 3. Results and Conclusion Both methods highlighted a medium acceptability of the bTB surveillance. The main elements having a negative influence were the consequences of official notification of a bTB suspect case in a farm, the low remuneration paid to private veterinarians for execution of intradermal tuberculin tests and the practical difficulties about the containment of the animals. Based on the two evaluation processes, relevant recommendations to improve the surveillance were made. Based on the comparison between the two evaluation processes, the

  2. High Bandwidth Differential Amplifier for Shock Experiments

    SciTech Connect

    Ross, P., Tran, V., Chau, R.

    2012-10-01

    We developed a high bandwidth differential amplifier for gas gun shock experiments. The circuit has a bandwidth up to 1 GHz, and is capable of measuring signals of ≤1.5 V with a common mode rejection of 250 V. Conductivity measurements of gas gun targets are measured by flowing high currents through the targets. The voltage is measured across the target using a technique similar to a four-point probe. Because of the design of the current source and load, the target voltage is approximately 250 V relative to ground. Since the expected voltage change in the target is < 1 V, the differential amplifier must have a large common mode rejection. Various amplifying designs are shown, although the increased amplification decreases bandwidth. Bench tests show that the amplifier can withstand significant common mode DC voltage and measure 10 ns, and 50 mV signals.

  3. A water framework directive (WFD) compliant determination of eologically acceptable flows in alpine rivers - a river type specific approach

    NASA Astrophysics Data System (ADS)

    Jäger, Paul; Zitek, Andreas

    2010-05-01

    Currently the EU-Water Framework Directive (WFD) represents the driving force behind the assessment for rehabilitation and conservation of aquatic resources throughout Europe. Hydropower production, often considered as "green energy", in the past has put significant pressures on river systems like fragmentation by weirs, impoundment, hydropeaking and water abstraction. Due to the limited availability of data for determining ecologically acceptable flow for rivers at water abstraction sites, a special monitoring program was conducted in the federal state of Salzburg in Austria from 2006 to 2009. Water abstraction sites at 19 hydropower plants, mostly within the trout region of the River Salzach catchment, were assessed in detail with regard to the effect of water abstraction on fish and macrozoobenthos. Based on a detailed assessment of the specific local hydro-morphological and biological situations, the validity of natural low flow criteria (Absolute Minimum Flow - AMF, the lowest daily average flow ever measured and Mean Annual Daily Low Flow - MADLF) as starting points for the determination of an ecologically acceptable flow was tested. It was assessed, if a good ecological status in accordance with the EU-WFD can be maintained at natural AMF. Additionally it was tested, if important habitat parameters describing connectivity, river type specific flow variability and river type specific habitats are maintained at this discharge. Habitat modelling was applied in some situations. Hydraulic results showed that at AMF the highest flow velocity classes were lost in most situations. When AMF was significantly undercut, flow velocities between 0,0 - 0,4 m/s became dominant, describing the loss of the river type specific flow character, leading to a loss of river type specific flow variability and habitats and increased sedimentation of fines. Furthermore limits for parameters describing connectivity for fish like maximum depth at the pessimum profile and minimum flow

  4. Passersby attracted by infants and mothers' acceptance of their approaches: A proximate factor for human cooperative breeding.

    PubMed

    Nishiyama, Kumiko; Oishi, Kouji; Saito, Atsuko

    2015-01-01

    Humans have engaged in unique cooperative breeding insofar as multiple in-group members help mothers. Two psychological-proximate factors maintain such a breeding system--various individuals' interest in infants and mothers' positive reactions toward individuals approaching their infants--which we investigated in the present study. In Study 1, we conducted field observations to examine the first factor: what types of passersby in Japan reacted to the mother and infant. This replicated studies conducted in Western countries more than 30 years ago, allowing for the examination of the influence of culture and time. The results confirmed the differences among age groups in frequency of looking at mother and infant, and predicted its universality, especially the rise in older adults. The sex difference was not significant. In Study 2, we gathered data via questionnaires and interviews using hypothetical scenarios to investigate the second factor: how mothers felt when their infants were approached by strangers. The results revealed that mothers received strangers' approaches positively. The present study showed that humans engaged in unique cooperative breeding in the Environment of Evolutionary Adaptedness (EEA), where mothers in modern society see strangers as potential helpers as part of the EEA. PMID:26093216

  5. 47 CFR 87.135 - Bandwidth of emission.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Bandwidth of emission. 87.135 Section 87.135... Technical Requirements § 87.135 Bandwidth of emission. (a) Occupied bandwidth is the width of a frequency... equal to 0.5 percent of the total mean power of a given emission. (b) The authorized bandwidth is...

  6. Coarse-Grain Bandwidth Estimation Techniques for Large-Scale Space Network

    NASA Technical Reports Server (NTRS)

    Cheung, Kar-Ming; Jennings, Esther

    2013-01-01

    In this paper, we describe a top-down analysis and simulation approach to size the bandwidths of a store-andforward network for a given network topology, a mission traffic scenario, and a set of data types with different latency requirements. We use these techniques to estimate the wide area network (WAN) bandwidths of the ground links for different architecture options of the proposed Integrated Space Communication and Navigation (SCaN) Network.

  7. Fast Faraday Cup With High Bandwidth

    DOEpatents

    Deibele, Craig E [Knoxville, TN

    2006-03-14

    A circuit card stripline Fast Faraday cup quantitatively measures the picosecond time structure of a charged particle beam. The stripline configuration maintains signal integrity, and stitching of the stripline increases the bandwidth. A calibration procedure ensures the measurement of the absolute charge and time structure of the charged particle beam.

  8. Power and bandwidth efficient modulation techniques

    NASA Astrophysics Data System (ADS)

    Le-Ngoc, T.; Feher, K.

    In this invited paper, a literature survey of power and bandwidth efficient modulation techniques is presented in historical progression from the widely known QPSK, OQPSK, and MSK to recently developed digital 4-phase modulation schemes. This historical review provides some insight into understanding the motivation, evolution and results of the development of new digital 4-phase modulation schemes applied to nonlinear channels.

  9. 47 CFR 101.109 - Bandwidth.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Bandwidth. 101.109 Section 101.109 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE... good engineering practice, except that Type B, damped-wave emission will not be authorized. (c)...

  10. 47 CFR 101.109 - Bandwidth.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Bandwidth. 101.109 Section 101.109 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE... good engineering practice, except that Type B, damped-wave emission will not be authorized. (c)...

  11. 47 CFR 101.109 - Bandwidth.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Bandwidth. 101.109 Section 101.109 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE..., consistent with efficient use of the spectrum and good engineering practice, except that Type B,...

  12. 47 CFR 2.202 - Bandwidths.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... emission I. NO MODULATING SIGNAL Continuous wave emission N0N (zero) II. AMPLITUDE MODULATION 1. Signal With Quantized or Digital Information Continuous wave telegraphy Bn=BK, K=5 for fading circuits, K=3... channels) Bn=sum of M for each sideband 2 channels, M=3000, Bandwidth: 6000 Hz=6 kHz 6K00B8E 3....

  13. Increasing the quantitative bandwidth of NMR measurements.

    PubMed

    Power, J E; Foroozandeh, M; Adams, R W; Nilsson, M; Coombes, S R; Phillips, A R; Morris, G A

    2016-02-18

    The frequency range of quantitative NMR is increased from tens to hundreds of kHz by a new pulse sequence, CHORUS. It uses chirp pulses to excite uniformly over very large bandwidths, yielding accurate integrals even for nuclei such as (19)F that have very wide spectra. PMID:26789115

  14. High bandwidth vapor density diagnostic system

    DOEpatents

    Globig, Michael A.; Story, Thomas W.

    1992-01-01

    A high bandwidth vapor density diagnostic system for measuring the density of an atomic vapor during one or more photoionization events. The system translates the measurements from a low frequency region to a high frequency, relatively noise-free region in the spectrum to provide improved signal to noise ratio.

  15. Bandwidth Enabled Flight Operations: Examining the Possibilities

    NASA Technical Reports Server (NTRS)

    Pisanich, Greg; Renema, Fritz; Clancy, Dan (Technical Monitor)

    2002-01-01

    The Bandwidth Enabled Flight Operations project is a research effort at the NASA Ames Research Center to investigate the use of satellite communications to improve aviation safety and capacity. This project is a follow on to the AeroSAPIENT Project, which demonstrated methods for transmitting high bandwidth data in various configurations. For this research, we set a goal to nominally use only 10 percent of the available bandwidth demonstrated by AeroSAPIENT or projected by near-term technology advances. This paper describes the results of our research, including available satellite bandwidth, commercial and research efforts to provide these services, and some of the limiting factors inherent with this communications medium. It also describes our investigation into the needs of the stakeholders (Airlines, Pilots, Cabin Crews, ATC, Maintenance, etc). The paper also describes our development of low-cost networked flight deck and airline operations center simulations that were used to demonstrate two application areas: Providing real time weather information to the commercial flight deck, and enhanced crew monitoring and control for airline operations centers.

  16. Bandwidth, Broadband, and Planning for Public Access

    ERIC Educational Resources Information Center

    Blowers, Helene

    2012-01-01

    Broadband and bandwidth allocation is an essential technology planning activity that libraries should address on a continual basis. There are five key factors that will impact your network's performance: 1. infrastructure, 2. network load, 3. workstation performance, 4. prioritization of services, and 5. network management. The author thinks it's…

  17. Terahertz bandwidth photonic Hilbert transformers based on synthesized planar Bragg grating fabrication.

    PubMed

    Sima, Chaotan; Gates, J C; Holmes, C; Mennea, P L; Zervas, M N; Smith, P G R

    2013-09-01

    Terahertz bandwidth photonic Hilbert transformers are proposed and experimentally demonstrated. The integrated device is fabricated via a direct UV grating writing technique in a silica-on-silicon platform. The photonic Hilbert transformer operates at bandwidths of up to 2 THz (~16 nm) in the telecom band, a 10-fold greater bandwidth than any previously reported experimental approaches. Achieving this performance requires detailed knowledge of the system transfer function of the direct UV grating writing technique; this allows improved linearity and yields terahertz bandwidth Bragg gratings with improved spectral quality. By incorporating a flat-top reflector and Hilbert grating with a waveguide coupler, an ultrawideband all-optical single-sideband filter is demonstrated. PMID:23988981

  18. Low bandwidth robust controllers for flight

    NASA Technical Reports Server (NTRS)

    Biezad, Daniel J.; Chou, Hwei-Lan

    1993-01-01

    Through throttle manipulations, engine thrust can be used for emergency flight control for multi-engine aircraft. Previous study by NASA Dryden has shown the use of throttles for emergency flight control to be very difficult. In general, manual fly-by-throttle is extremely difficult - with landing almost impossible, but control augmentation makes runway landings feasible. Flight path control using throttles-only to achieve safe emergency landing for a large jet transport airplane, Boeing 720, was investigated using Quantitative Feedback Theory (QFT). Results were compared to an augmented control developed in a previous simulation study. The control augmentation corrected the unsatisfactory open-loop characteristics by increasing system bandwidth and damping, but increasing the control bandwidth substantially proved very difficult. The augmented pitch control is robust under no or moderate turbulence. The augmented roll control is sensitive to configuration changes.

  19. Low Bandwidth Robust Controllers for Flight

    NASA Technical Reports Server (NTRS)

    Biezad, Daniel J.; Chou, Hwei-Lan

    1993-01-01

    Through throttle manipulations, engine thrust can be used for emergency flight control for multi-engine aircraft. Previous study by NASA Dryden has shown the use of throttles for emergency flight control to be very difficult. In general, manual fly-by-throttle is extremely difficult - with landing almost impossible, but control augmentation makes runway landings feasible. Flight path control using throttles-only to achieve safe emergency landing for a large jet transport airplane, Boeing 720, was investigated using Quantitative Feedback Theory (QFT). Results were compared to an augmented control developed in a previous simulation study. The control augmentation corrected the unsatisfactory open-loop characteristics by increasing system bandwidth and damping, but increasing the control bandwidth substantially proved very difficult. The augmented pitch control is robust under no or moderate turbulence. The augmented roll control is sensitive to configuration changes.

  20. High Bandwidth Differential Amplifier for Shock Experiments

    SciTech Connect

    Ross, P. W., Tran, V., Chau, R.

    2012-04-30

    We developed a high bandwidth differential amplifier for gas gun shock experiments/applications. The circuit has a bandwidth > 1 GHz, and is capable of measuring signals of ≤1.5 V with a common mode rejection of 250 V. Conductivity measurements of gas gun targets are measured by flowing high currents through the targets. The voltage is measured across the target using a technique similar to a four-point probe. Because of the design of the current source and load, the target voltage is approximately 250 V relative to ground. Since the expected voltage change in the target is < 1 V, the differential amplifier must have a large common mode rejection. High pass filters suppress internal ringing of operational amplifiers. Results of bench tests are shown.

  1. Bandwidth of the contrast sensitivity function as an index of spatial vision with application to refraction.

    PubMed

    Jiang, B C; Scialfa, C T; Tyrrell, R A; Garvey, P M; Leibowitz, H W

    1990-04-01

    The contrast sensitivity function (CSF), although containing more information than traditional measures of acuity, has found difficulty gaining clinical acceptance. The hesitancy of clinicians to adopt the CSF stems, in part, from the fact that it is not as readily interpreted as is acuity. In order to facilitate such interpretation, five indices of spatial vision which are derivable from the CSF were examined in a sample of 287 persons aged 5 to 85 years. All indices were found to be both age-sensitive and strongly related to each other, but bandwidth of the CSF was chosen as a practical index for clinical settings. In a second study, acuity and CSF bandwidth were measured under 0 to +/- 1 D optical blur. It was found that the correction providing best acuity also maximized CSF bandwidth, and that bandwidth was more sensitive to optical blur than was acuity. Results support the assertion that CSF bandwidth is a readily interpreted index of spatial vision that can be measured efficiently within the context of clinical refraction. PMID:2342788

  2. Bandwidth and SIMDUCE as simulator fidelity criteria

    NASA Technical Reports Server (NTRS)

    Key, David

    1992-01-01

    The potential application of two concepts from the new Handling Qualities Specification for Military Rotorcraft was discussed. The first concept is bandwidth, a measure of the dynamic response to control. The second is a qualitative technique developed for assessing the visual cue environment the pilot has in bad weather and at night. Simulated Day Usable Cue Environment (SIMDUCE) applies this concept to assessing the day cuing fidelity in the simulator.

  3. Bandwidth efficient coding for satellite communications

    NASA Astrophysics Data System (ADS)

    Lin, Shu; Costello, Daniel J., Jr.; Miller, Warner H.; Morakis, James C.; Poland, William B., Jr.

    1992-02-01

    An error control coding scheme was devised to achieve large coding gain and high reliability by using coded modulation with reduced decoding complexity. To achieve a 3 to 5 dB coding gain and moderate reliability, the decoding complexity is quite modest. In fact, to achieve a 3 dB coding gain, the decoding complexity is quite simple, no matter whether trellis coded modulation or block coded modulation is used. However, to achieve coding gains exceeding 5 dB, the decoding complexity increases drastically, and the implementation of the decoder becomes very expensive and unpractical. The use is proposed of coded modulation in conjunction with concatenated (or cascaded) coding. A good short bandwidth efficient modulation code is used as the inner code and relatively powerful Reed-Solomon code is used as the outer code. With properly chosen inner and outer codes, a concatenated coded modulation scheme not only can achieve large coding gains and high reliability with good bandwidth efficiency but also can be practically implemented. This combination of coded modulation and concatenated coding really offers a way of achieving the best of three worlds, reliability and coding gain, bandwidth efficiency, and decoding complexity.

  4. On the bandwidth of the plenoptic function.

    PubMed

    Do, Minh N; Marchand-Maillet, Davy; Vetterli, Martin

    2012-02-01

    The plenoptic function (POF) provides a powerful conceptual tool for describing a number of problems in image/video processing, vision, and graphics. For example, image-based rendering is shown as sampling and interpolation of the POF. In such applications, it is important to characterize the bandwidth of the POF. We study a simple but representative model of the scene where band-limited signals (e.g., texture images) are "painted" on smooth surfaces (e.g., of objects or walls). We show that, in general, the POF is not band limited unless the surfaces are flat. We then derive simple rules to estimate the essential bandwidth of the POF for this model. Our analysis reveals that, in addition to the maximum and minimum depths and the maximum frequency of painted signals, the bandwidth of the POF also depends on the maximum surface slope. With a unifying formalism based on multidimensional signal processing, we can verify several key results in POF processing, such as induced filtering in space and depth-corrected interpolation, and quantify the necessary sampling rates. PMID:21827973

  5. Bandwidth efficient coding for satellite communications

    NASA Technical Reports Server (NTRS)

    Lin, Shu; Costello, Daniel J., Jr.; Miller, Warner H.; Morakis, James C.; Poland, William B., Jr.

    1992-01-01

    An error control coding scheme was devised to achieve large coding gain and high reliability by using coded modulation with reduced decoding complexity. To achieve a 3 to 5 dB coding gain and moderate reliability, the decoding complexity is quite modest. In fact, to achieve a 3 dB coding gain, the decoding complexity is quite simple, no matter whether trellis coded modulation or block coded modulation is used. However, to achieve coding gains exceeding 5 dB, the decoding complexity increases drastically, and the implementation of the decoder becomes very expensive and unpractical. The use is proposed of coded modulation in conjunction with concatenated (or cascaded) coding. A good short bandwidth efficient modulation code is used as the inner code and relatively powerful Reed-Solomon code is used as the outer code. With properly chosen inner and outer codes, a concatenated coded modulation scheme not only can achieve large coding gains and high reliability with good bandwidth efficiency but also can be practically implemented. This combination of coded modulation and concatenated coding really offers a way of achieving the best of three worlds, reliability and coding gain, bandwidth efficiency, and decoding complexity.

  6. Effective File I/O Bandwidth Benchmark

    SciTech Connect

    Rabenseifner, R.; Koniges, A.E.

    2000-02-15

    The effective I/O bandwidth benchmark (b{_}eff{_}io) covers two goals: (1) to achieve a characteristic average number for the I/O bandwidth achievable with parallel MPI-I/O applications, and (2) to get detailed information about several access patterns and buffer lengths. The benchmark examines ''first write'', ''rewrite'' and ''read'' access, strided (individual and shared pointers) and segmented collective patterns on one file per application and non-collective access to one file per process. The number of parallel accessing processes is also varied and well-formed I/O is compared with non-well formed. On systems, meeting the rule that the total memory can be written to disk in 10 minutes, the benchmark should not need more than 15 minutes for a first pass of all patterns. The benchmark is designed analogously to the effective bandwidth benchmark for message passing (b{_}eff) that characterizes the message passing capabilities of a system in a few minutes. First results of the b{_}eff{_}io benchmark are given for IBM SP and Cray T3E systems and compared with existing benchmarks based on parallel Posix-I/O.

  7. Exploiting Sparse Dynamics For Bandwidth Reduction In Cooperative Sensing Systems

    NASA Astrophysics Data System (ADS)

    Ganapathy, Harish; Caramanis, Constantine; Ying, Lei

    2013-07-01

    Recently, there has been a significant interest in developing cooperative sensing systems for certain types of wireless applications. In such systems, a group of sensing nodes periodically collect measurements about the signals being observed in the given geographical region and transmit these measurements to a central node, which in turn processes this information to recover the signals. For example, in cognitive radio networks, the signals of interest are those generated by the primary transmitters and the sensing nodes are the secondary users. In such networks, it is critically important to be able to reliably determine the presence or absence of primary transmitters in order to avoid causing interference. The standard approach to transmit these measurements from sensor the nodes to the fusion center has been to use orthogonal channels. Such an approach quickly places a burden on the control-channel-capacity of the network that would scale linearly in the number of cooperating sensing nodes. In this paper, we show that as long as one condition is satisfied: the dynamics of the observed signals are sparse, i.e., the observed signals do not change their values very rapidly in relation to the time-scale at which the measurements are collected, we can significantly reduce the control bandwidth of the system while achieving the full (linear) bandwidth performance.

  8. Progressive raster imagery beyond a means to overcome limited bandwidth

    NASA Astrophysics Data System (ADS)

    Rosenbaum, René; Schumann, Heidrun

    2009-02-01

    Progressive refinement is a well-established approach to overcome bandwidth limitations in mobile environments. One outstanding benefit compared to relates approaches is the provision of meaningful content previews during data transfer or processing. Although highly relevant and useful, however, related literature only addresses the support of this functionality by certain communication stages or proposes systems for specific use cases. No publication is concerned with an abstraction or formalization of progression or takes advantage of its beneficial properties in other application fields. In this publication we want to give a general view to progression, its key concepts, attributes, and common data processing pipeline. Thereby, we abstract from specifics and usage scenarios in order to simplify the development of new algorithms and schemes and to derive guidelines for its general application. To show that progression is also able to solve problems beyond limited bandwidth, this contribution is also concerned with the introduction of new application areas. The novel idea of content-oriented refinement allows emphasizing important image regions by an animated tour-through-the-data. It will also be shown that progressive representations are a very effective means for device adaptation. Both applications are motivated, discussed, and illustrated by different examples.

  9. Acceptance speech.

    PubMed

    Carpenter, M

    1994-01-01

    In Bangladesh, the assistant administrator of USAID gave an acceptance speech at an awards ceremony on the occasion of the 25th anniversary of oral rehydration solution (ORS). The ceremony celebrated the key role of the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B) in the discovery of ORS. Its research activities over the last 25 years have brought ORS to every village in the world, preventing more than a million deaths each year. ORS is the most important medical advance of the 20th century. It is affordable and client-oriented, a true appropriate technology. USAID has provided more than US$ 40 million to ICDDR,B for diarrheal disease and measles research, urban and rural applied family planning and maternal and child health research, and vaccine development. ICDDR,B began as the relatively small Cholera Research Laboratory and has grown into an acclaimed international center for health, family planning, and population research. It leads the world in diarrheal disease research. ICDDR,B is the leading center for applied health research in South Asia. It trains public health specialists from around the world. The government of Bangladesh and the international donor community have actively joined in support of ICDDR,B. The government applies the results of ICDDR,B research to its programs to improve the health and well-being of Bangladeshis. ICDDR,B now also studies acute respiratory diseases and measles. Population and health comprise 1 of USAID's 4 strategic priorities, the others being economic growth, environment, and democracy, USAID promotes people's participation in these 4 areas and in the design and implementation of development projects. USAID is committed to the use and improvement of ORS and to complementary strategies that further reduce diarrhea-related deaths. Continued collaboration with a strong user perspective and integrated services will lead to sustainable development. PMID:12345470

  10. Acceptance speech.

    PubMed

    Yusuf, C K

    1994-01-01

    I am proud and honored to accept this award on behalf of the Government of Bangladesh, and the millions of Bangladeshi children saved by oral rehydration solution. The Government of Bangladesh is grateful for this recognition of its commitment to international health and population research and cost-effective health care for all. The Government of Bangladesh has already made remarkable strides forward in the health and population sector, and this was recognized in UNICEF's 1993 "State of the World's Children". The national contraceptive prevalence rate, at 40%, is higher than that of many developed countries. It is appropriate that Bangladesh, where ORS was discovered, has the largest ORS production capacity in the world. It was remarkable that after the devastating cyclone in 1991, the country was able to produce enough ORS to meet the needs and remain self-sufficient. Similarly, Bangladesh has one of the most effective, flexible and efficient control of diarrheal disease and epidemic response program in the world. Through the country, doctors have been trained in diarrheal disease management, and stores of ORS are maintained ready for any outbreak. Despite grim predictions after the 1991 cyclone and the 1993 floods, relatively few people died from diarrheal disease. This is indicative of the strength of the national program. I want to take this opportunity to acknowledge the contribution of ICDDR, B and the important role it plays in supporting the Government's efforts in the health and population sector. The partnership between the Government of Bangladesh and ICDDR, B has already borne great fruit, and I hope and believe that it will continue to do so for many years in the future. Thank you. PMID:12345479

  11. Spin-torque diode with tunable sensitivity and bandwidth by out-of-plane magnetic field

    NASA Astrophysics Data System (ADS)

    Li, X.; Zheng, C.; Zhou, Y.; Kubota, H.; Yuasa, S.; Pong, Philip W. T.

    2016-06-01

    Spin-torque diodes based on nanosized magnetic tunnel junctions are novel microwave detectors with high sensitivity and wide frequency bandwidth. While previous reports mainly focus on improving the sensitivity, the approaches to extend the bandwidth are limited. This work experimentally demonstrates that through optimizing the orientation of the external magnetic field, wide bandwidth can be achieved while maintaining high sensitivity. The mechanism of the frequency- and sensitivity-tuning is investigated through analyzing the dependence of resonant frequency and DC voltage on the magnitude and the tilt angle of hard-plane magnetic field. The frequency dependence is qualitatively explicated by Kittel's ferromagnetic resonance model. The asymmetric resonant frequency at positive and negative magnetic field is verified by the numerical simulation considering the in-plane anisotropy. The DC voltage dependence is interpreted through evaluating the misalignment angle between the magnetization of the free layer and the reference layer. The tunability of the detector performance by the magnetic field angle is evaluated through characterizing the sensitivity and bandwidth under 3D magnetic field. The frequency bandwidth up to 9.8 GHz or maximum sensitivity up to 154 mV/mW (after impedance mismatch correction) can be achieved by tuning the angle of the applied magnetic field. The results show that the bandwidth and sensitivity can be controlled and adjusted through optimizing the orientation of the magnetic field for various applications and requirements.

  12. 47 CFR 78.104 - Authorized bandwidth and emission designator.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... designator. (a) The authorized bandwidth permitted to be used by a CARS station and specified in the station... bandwidth for the station on the lesser of the occupied or necessary bandwidth where a persuasive showing is... with § 78.103(b)(1) and, additionally, will permit 99 percent of the total radiated power to be...

  13. 47 CFR 78.104 - Authorized bandwidth and emission designator.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... designator. (a) The authorized bandwidth permitted to be used by a CARS station and specified in the station... bandwidth for the station on the lesser of the occupied or necessary bandwidth where a persuasive showing is... with § 78.103(b)(1) and, additionally, will permit 99 percent of the total radiated power to be...

  14. An improved harmony search algorithm with dynamically varying bandwidth

    NASA Astrophysics Data System (ADS)

    Kalivarapu, J.; Jain, S.; Bag, S.

    2016-07-01

    The present work demonstrates a new variant of the harmony search (HS) algorithm where bandwidth (BW) is one of the deciding factors for the time complexity and the performance of the algorithm. The BW needs to have both explorative and exploitative characteristics. The ideology is to use a large BW to search in the full domain and to adjust the BW dynamically closer to the optimal solution. After trying a series of approaches, a methodology inspired by the functioning of a low-pass filter showed satisfactory results. This approach was implemented in the self-adaptive improved harmony search (SIHS) algorithm and tested on several benchmark functions. Compared to the existing HS algorithm and its variants, SIHS showed better performance on most of the test functions. Thereafter, the algorithm was applied to geometric parameter optimization of a friction stir welding tool.

  15. Optical performance monitoring for OFDM using low bandwidth coherent receivers.

    PubMed

    Chen, Simin; Anderson, Trevor; Hewitt, Don; Tran, An V; Zhu, Chen; Du, Liang B; Lowery, Arthur J; Skafidas, Efstratios

    2012-12-17

    We propose using low bandwidth coherent receivers for distributed optical performance monitoring. We demonstrate optical signal-to-noise ratio (OSNR) monitoring of both 20-Gb/s single-polarization and 40-Gb/s polarization-multiplexed coherent optical orthogonal frequency-division multiplexing (CO-OFDM) signals with a 0.8-GHz receiver using both data-aided (DA) and non-data-aided (NDA) approaches. The sampling rate of the performance monitor is much lower than the signal baud rate, so provides a cost-effective solution for distributed optical performance monitoring. The proposed method is demonstrated experimentally and through simulation. The results show that after calibration the OSNR monitoring error is less than 1 dB and the two approaches are not affected by fiber dispersion after 800-km transmission and 30-ps differential group delay (DGD). PMID:23263110

  16. Bandwidth Constrained Multi-interface Networks

    NASA Astrophysics Data System (ADS)

    D'Angelo, Gianlorenzo; di Stefano, Gabriele; Navarra, Alfredo

    In heterogeneous networks, devices can communicate by means of multiple wired or wireless interfaces. By switching among interfaces or by combining the available interfaces, each device might establish several connections. A connection is established when the devices at its endpoints share at least one active interface. Each interface is assumed to require an activation cost, and provides a communication bandwidth. In this paper, we consider the problem of activating the cheapest set of interfaces among a network G = (V,E) in order to guarantee a minimum bandwidth B of communication between two specified nodes. Nodes V represent the devices, edges E represent the connections that can be established. In practical cases, a bounded number k of different interfaces among all the devices can be considered. Despite this assumption, the problem turns out to be NP-hard even for small values of k and Δ, where Δ is the maximum degree of the network. In particular, the problem is NP-hard for any fixed k ≥ 2 and Δ ≥ 3, while it is polynomially solvable when k = 1, or Δ ≤ 2 and k = O(1). Moreover, we show that the problem is not approximable within ηlogB or Ω(loglog|V|) for any fixed k ≥ 3, Δ ≥ 3, and for a certain constant η, unless P={NP}. We then provide an approximation algorithm with ratio guarantee of b max , where b max is the maximum communication bandwidth allowed among all the available interfaces. Finally, we focus on particular cases by providing complexity results and polynomial algorithms for Δ ≤ 2.

  17. Molecular dissociation of HD^+ by broad bandwidth chirped laser pulses: a molecular bandwidth filter

    NASA Astrophysics Data System (ADS)

    Zohrabi, M.; Ablikim, U.; Carnes, K. D.; Esry, B. D.; Ben-Itzhak, I.

    2012-06-01

    We employ a coincidence 3D momentum imaging method to study the fragmentation of HD^+ following interaction with an intense, 800 nm, 25 fs Fourier transform-limited (FTL) laser pulse. The broad bandwidth of our FTL pulse prevents us from observing vibrational peaks that one would expect to see using longer FTL laser pulses ˜100 fs. However, by chirping the pulse either positively or negatively, while maintaining a fixed bandwidth, we were able to measure vibrational structure. The kinetic energy release of these vibrational peaks are shifted up or down depending on the sign of the chirp.ootnotetextV. S. Prabhudesai et al., Phys. Rev. A 81, 023401 (2010). We will address the question of why the vibrational structure is observed in spite of the broad bandwidth of the chirped laser pulses.

  18. Confocal microscopy via multimode fibers: fluorescence bandwidth

    NASA Astrophysics Data System (ADS)

    Loterie, Damien; Psaltis, Demetri; Moser, Christophe

    2016-03-01

    We recently described a method for confocal reflection imaging through fibers, as a way to increase contrast when imaging unstained biological specimens. Using a transmission matrix, focused spots can be created at the distal end of a fiber. The backscattered field coming back from the sample can be filtered using optical correlation to obtain spatial selectivity in the detection. In this proceedings article, we briefly review the working principle of this method, and we discuss how the scheme could be adapted to confocal fluorescence imaging. In particular, we show simulations of the achievable detection bandwidth when using step-index multimode fibers as imaging devices.

  19. Bandwidth reconfigurable microwave photonic filter based on stimulated Brillouin scattering

    NASA Astrophysics Data System (ADS)

    Xiao, Yongchuan; Wang, Xin; Zhang, Youdi; Dong, Wei; Zhang, Xindong; Liu, Caixia; Ruan, Shengping; Chen, Weiyou

    2015-01-01

    A bandwidth reconfigurable microwave photonic filter is proposed and numerically analyzed employing Brillouin gain spectrum narrowing and broadening. The stimulated Brillouin scattering (SBS) process is used to convert the phase modulation to intensity modulation to generate filter passband. Due to the fact that the passband is formed by mapping the Brillouin gain spectrum, bandwidth reconfiguration can be implemented by changing Brillouin gain linewidth. In this paper, both bandwidth reduction and increase are included in a single system and the details of gain spectrum narrowing and broadening are demonstrated. Theoretically, nearly 60% bandwidth reduction and hundreds times of bandwidth increase are achieved as compared to the case without gain spectrum process.

  20. Variable bandwidth broadcasting protocol for video-on-demand

    NASA Astrophysics Data System (ADS)

    Paris, Jehan-Francois; Long, Darrell D. E.

    2003-01-01

    We present the first broadcasting protocol that can alter the number of channels allocated to a given video without inconveniencing the viewer and without causing any temporary bandwidth surge. Our variable bandwidth broadcasting (VBB) protocol assigns to each video a minimum number of channels whose bandwidths are all equal to the video consumption rate. Additional channels can be assigned to the video at any time to reduce the customer waiting time or retaken to free server bandwidth. The cost of this additional flexibility is quite reasonable as the bandwidth requirements of our VBB fall between those of the fast broadcasting protocol and the new pagoda broadcasting protocol.

  1. Remote driving with reduced bandwidth communication

    NASA Technical Reports Server (NTRS)

    Depiero, Frederick W.; Noell, Timothy E.; Gee, Timothy F.

    1993-01-01

    Oak Ridge National Laboratory has developed a real-time video transmission system for low bandwidth remote operations. The system supports both continuous transmission of video for remote driving and progressive transmission of still images. Inherent in the system design is a spatiotemporal limitation to the effects of channel errors. The average data rate of the system is 64,000 bits/s, a compression of approximately 1000:1 for the black and white National Television Standard Code video. The image quality of the transmissions is maintained at a level that supports teleoperation of a high mobility multipurpose wheeled vehicle at speeds up to 15 mph on a moguled dirt track. Video compression is achieved by using Laplacian image pyramids and a combination of classical techniques. Certain subbands of the image pyramid are transmitted by using interframe differencing with a periodic refresh to aid in bandwidth reduction. Images are also foveated to concentrate image detail in a steerable region. The system supports dynamic video quality adjustments between frame rate, image detail, and foveation rate. A typical configuration for the system used during driving has a frame rate of 4 Hz, a compression per frame of 125:1, and a resulting latency of less than 1s.

  2. Tunable pulsed narrow bandwidth light source

    DOEpatents

    Powers, Peter E.; Kulp, Thomas J.

    2002-01-01

    A tunable pulsed narrow bandwidth light source and a method of operating a light source are provided. The light source includes a pump laser, first and second non-linear optical crystals, a tunable filter, and light pulse directing optics. The method includes the steps of operating the pump laser to generate a pulsed pump beam characterized by a nanosecond pulse duration and arranging the light pulse directing optics so as to (i) split the pulsed pump beam into primary and secondary pump beams; (ii) direct the primary pump beam through an input face of the first non-linear optical crystal such that a primary output beam exits from an output face of the first non-linear optical crystal; (iii) direct the primary output beam through the tunable filter to generate a sculpted seed beam; and direct the sculpted seed beam and the secondary pump beam through an input face of the second non-linear optical crystal such that a secondary output beam characterized by at least one spectral bandwidth on the order of about 0.1 cm.sup.-1 and below exits from an output face of the second non-linear optical crystal.

  3. Bandwidth Efficient Baseband Multi-Modulator

    NASA Technical Reports Server (NTRS)

    Fong, Wai; Gray, Andrew; Yeh, Pen-Shu

    2003-01-01

    The High Rate Baseband Multi-Modulator (HRBM) ASIC is being developed to provide High-speed Bandwidth Efficient Modulations to NASA missions. Bandwidth efficiencies from 2.0 bits/symbol/Hz to 2.75 bits/symbl/Hz are selectable from three CCSDS modulations: Gaussian Minimum Shift Keying (GMSK), Filter Offset Quadrature Phase Shift Keying (Filtered- OQSK) and 8-Phase Shift Keying Trellis Coded Modulation (8-PSK TCM). An FPGA version of the HRBM is developed first to verify the individual modulation designs and characterize timing and performance issues involved with digital baseband modulation synthesis. A Finite Input Response (FIR) filter is included to provided baseband pulse shaping to reduce out-of-band spectral emissions. This is filter is programmable and can be tailored to meet system requirements. The ASIC is targeted to provide up to 600 Mbps throughput and will provide serial as well as parallel input. This paper provides an overview of the technology development and current status.

  4. Coherence bandwidth loss in transionospheric radio propagation

    NASA Technical Reports Server (NTRS)

    Rino, C. L.; Gonzalez, V. H.; Hessing, A. R.

    1980-01-01

    In this report a theoretical model is developed that predicts the single-point, two-frequency coherence function for transionospheric radio waves. The theoretical model is compared to measured complex frequency correlation coefficients using data from the seven equispaced, phase-coherent UHF signals transmitted by the Wideband satellite. The theory and data are in excellent agreement. The theory is critically dependent upon the power-law index, and the frequency coherence data clearly favor the comparatively small spectral indices that have been consistently measured from the wideband satellite phase data. A model for estimating the pulse delay jitter induced by the coherence bandwidth loss is also developed and compared with the actual delay jitter observed on synthesized pulses obtained from the Wideband UFH comb. The results are in good agreement with the theory. The results presented in this report, which are based on an asymptotic theory, are compared with the more commonly used quadratic theory. The model developed and validated in this report can be used to predict the effects of coherence bandwidth loss in disturbed nuclear environments. Simple formulas for the resultant pulse delay jitter are derived that can be used in predictive codes.

  5. Broadening the interface bandwidth in simulation based training

    NASA Technical Reports Server (NTRS)

    Somers, Larry E.

    1989-01-01

    Currently most computer based simulations rely exclusively on computer generated graphics to create the simulation. When training is involved, the method almost exclusively used to display information to the learner is text displayed on the cathode ray tube. MICROEXPERT Systems is concentrating on broadening the communications bandwidth between the computer and user by employing a novel approach to video image storage combined with sound and voice output. An expert system is used to combine and control the presentation of analog video, sound, and voice output with computer based graphics and text. Researchers are currently involved in the development of several graphics based user interfaces for NASA, the U.S. Army, and the U.S. Navy. Here, the focus is on the human factors considerations, software modules, and hardware components being used to develop these interfaces.

  6. Ptychography with broad-bandwidth radiation

    SciTech Connect

    Enders, B. Dierolf, M.; Stockmar, M.; Pfeiffer, F.; Cloetens, P.; Thibault, P.

    2014-04-28

    Ptychography, a scanning Coherent Diffractive Imaging (CDI) technique, has quickly gained momentum as a robust method to deliver quantitative images of extended specimens. A current conundrum for the development of X-ray CDI is the conflict between a need for higher flux to reach higher resolutions and the requirement to strongly filter the incident beam to satisfy the tight coherence prerequisite of the technique. Latest developments in algorithmic treatment of ptychographic data indicate that the technique is more robust than initially assumed, so that some experimental limitations can be substantially relaxed. Here, we demonstrate that ptychography can be conducted in conditions that were up to now considered insufficient, using a broad-bandwidth X-ray beam and an integrating scintillator-based detector. Our work shows the wide applicability of ptychography and paves the way to high-throughput, high-flux diffractive imaging.

  7. High bandwidth magnetically isolated signal transmission circuit

    NASA Technical Reports Server (NTRS)

    Repp, John Donald (Inventor)

    2005-01-01

    Many current electronic systems incorporate expensive or sensitive electrical components. Because electrical energy is often generated or transmitted at high voltages, the power supplies to these electronic systems must be carefully designed. Power supply design must ensure that the electrical system being supplied with power is not exposed to excessive voltages or currents. In order to isolate power supplies from electrical equipment, many methods have been employed. These methods typically involve control systems or signal transfer methods. However, these methods are not always suitable because of their drawbacks. The present invention relates to transmitting information across an interface. More specifically, the present invention provides an apparatus for transmitting both AC and DC information across a high bandwidth magnetic interface with low distortion.

  8. RAID Disk Arrays for High Bandwidth Applications

    NASA Technical Reports Server (NTRS)

    Moren, Bill

    1996-01-01

    High bandwidth applications require large amounts of data transferred to/from storage devices at extremely high data rates. Further, these applications often are 'real time' in which access to the storage device must take place on the schedule of the data source, not the storage. A good example is a satellite downlink - the volume of data is quite large and the data rates quite high (dozens of MB/sec). Further, a telemetry downlink must take place while the satellite is overhead. A storage technology which is ideally suited to these types of applications is redundant arrays of independent discs (RAID). Raid storage technology, while offering differing methodologies for a variety of applications, supports the performance and redundancy required in real-time applications. Of the various RAID levels, RAID-3 is the only one which provides high data transfer rates under all operating conditions, including after a drive failure.

  9. PEP Deployment and Bandwidth Management Issues

    NASA Astrophysics Data System (ADS)

    Younghusband, Charles; Slade, Peter; Weaver, Jeff

    This paper will discuss current deployment scenarios for Performance Enhancement Proxies (PEP) technologies in broadband satellite access systems from the perspective of one PEP technology provider. Recent improvements such as DVB-S2 can provide substantial gains at the link layer. In order to achieve further efficiency gains, the satellite industry is now forced to look elsewhere - namely other layers in the data communications network stack. Satellite terminal manufacturers are now moving beyond basic TCP acceleration techniques to more comprehensive optimization techniques that incorporate advances in data compression and flexibility for more deployment scenarios. Some of the advances for PEP technology are in part due to CPU and memory technology advances, resulting in increasingly affordable access to computing power, allowing PEP manufacturers deliver substantial performance and bandwidth savings gains.

  10. Optimal filter bandwidth for pulse oximetry

    NASA Astrophysics Data System (ADS)

    Stuban, Norbert; Niwayama, Masatsugu

    2012-10-01

    Pulse oximeters contain one or more signal filtering stages between the photodiode and microcontroller. These filters are responsible for removing the noise while retaining the useful frequency components of the signal, thus improving the signal-to-noise ratio. The corner frequencies of these filters affect not only the noise level, but also the shape of the pulse signal. Narrow filter bandwidth effectively suppresses the noise; however, at the same time, it distorts the useful signal components by decreasing the harmonic content. In this paper, we investigated the influence of the filter bandwidth on the accuracy of pulse oximeters. We used a pulse oximeter tester device to produce stable, repetitive pulse waves with digitally adjustable R ratio and heart rate. We built a pulse oximeter and attached it to the tester device. The pulse oximeter digitized the current of its photodiode directly, without any analog signal conditioning. We varied the corner frequency of the low-pass filter in the pulse oximeter in the range of 0.66-15 Hz by software. For the tester device, the R ratio was set to R = 1.00, and the R ratio deviation measured by the pulse oximeter was monitored as a function of the corner frequency of the low-pass filter. The results revealed that lowering the corner frequency of the low-pass filter did not decrease the accuracy of the oxygen level measurements. The lowest possible value of the corner frequency of the low-pass filter is the fundamental frequency of the pulse signal. We concluded that the harmonics of the pulse signal do not contribute to the accuracy of pulse oximetry. The results achieved by the pulse oximeter tester were verified by human experiments, performed on five healthy subjects. The results of the human measurements confirmed that filtering out the harmonics of the pulse signal does not degrade the accuracy of pulse oximetry.

  11. Dynamic Online Bandwidth Adjustment Scheme Based on Kalai-Smorodinsky Bargaining Solution

    NASA Astrophysics Data System (ADS)

    Kim, Sungwook

    Virtual Private Network (VPN) is a cost effective method to provide integrated multimedia services. Usually heterogeneous multimedia data can be categorized into different types according to the required Quality of Service (QoS). Therefore, VPN should support the prioritization among different services. In order to support multiple types of services with different QoS requirements, efficient bandwidth management algorithms are important issues. In this paper, I employ the Kalai-Smorodinsky Bargaining Solution (KSBS) for the development of an adaptive bandwidth adjustment algorithm. In addition, to effectively manage the bandwidth in VPNs, the proposed control paradigm is realized in a dynamic online approach, which is practical for real network operations. The simulations show that the proposed scheme can significantly improve the system performances.

  12. Practical security of continuous-variable quantum key distribution with finite sampling bandwidth effects

    NASA Astrophysics Data System (ADS)

    Wang, Chao; Huang, Peng; Huang, Duan; Lin, Dakai; Zeng, Guihua

    2016-02-01

    Practical security of the continuous-variable quantum key distribution (CVQKD) system with finite sampling bandwidth of analog-to-digital converter (ADC) at the receiver's side is investigated. We find that the finite sampling bandwidth effects may decrease the lower bound of secret key rate without awareness of the legitimate communicators. This leaves security loopholes for Eve to attack the system. In addition, this effect may restrains the linear relationship of secret key bit rate with repetition rate of the system; subsequently, there is a saturation value for the secret key bit rate with the repetition rate. To resist such kind of effects, we propose a dual sampling detection approach in which two ADCs are employed so that the finite sampling bandwidth effects are removed.

  13. Compact antenna arrays with wide bandwidth and low sidelobe levels

    SciTech Connect

    Strassner, II, Bernd H.

    2014-09-09

    Highly efficient, low cost, easily manufactured SAR antenna arrays with lightweight low profiles, large instantaneous bandwidths and low SLL are disclosed. The array topology provides all necessary circuitry within the available antenna aperture space and between the layers of material that comprise the aperture. Bandwidths of 15.2 GHz to 18.2 GHz, with 30 dB SLLs azimuthally and elevationally, and radiation efficiencies above 40% may be achieved. Operation over much larger bandwidths is possible as well.

  14. Frequency Bandwidth Optimization of Left-Handed Metamaterial

    NASA Technical Reports Server (NTRS)

    Chevalier, Christine T.; Wilson, Jeffrey D.

    2004-01-01

    Recently, left-handed metamaterials (LHM s) have been demonstrated with an effective negative index of refraction and with antiparallel group and phase velocities for microwave radiation over a narrow frequency bandwidth. In order to take advantage of these characteristics for practical applications, it will be beneficial to develop LHM s with increased frequency bandwidth response and lower losses. In this paper a commercial three-dimensional electromagnetic simulation code is used to explore the effects of geometry parameter variations on the frequency bandwidth of a LHM at microwave frequencies. Utilizing an optimizing routine in the code, a geometry was generated with a bandwidth more than twice as large as the original geometry.

  15. PIC Simulation of Laser Plasma Interactions with Temporal Bandwidths

    NASA Astrophysics Data System (ADS)

    Tsung, Frank; Weaver, J.; Lehmberg, R.

    2015-11-01

    We are performing particle-in-cell simulations using the code OSIRIS to study the effects of laser plasma interactions in the presence of temperal bandwidths under conditions relevant to current and future shock ignition experiments on the NIKE laser. Our simulations show that, for sufficiently large bandwidth, the saturation level, and the distribution of hot electrons, can be effected by the addition of temporal bandwidths (which can be accomplished in experiments using smoothing techniques such as SSD or ISI). We will show that temporal bandwidth along play an important role in the control of LPI's in these lasers and discuss future directions. This work is conducted under the auspices of NRL.

  16. Mid-bandwidth loudness depression in hearing-impaired listeners.

    PubMed

    Hots, Jan; Jarzombek, Katrin; Verhey, Jesko L

    2016-05-01

    The loudness of a bandpass-filtered noise depends on its bandwidth. For bandwidths larger than a critical bandwidth, loudness increases as the bandwidth increases, an effect commonly referred to as spectral loudness summation. For bandwidths smaller than the critical bandwidth, it was shown recently for normal-hearing listeners that loudness decreases as the bandwidth increases. This study investigated if listeners with a hearing impairment of primarily cochlear origin also showed this effect. Levels at equal loudness between a 1500-Hz pure-tone reference and noise-band targets centered at 1500 Hz were measured for bandwidths in the range from 15 to 1620 Hz. The reference level was adjusted individually on the basis of the audiogram. The average level difference at equal loudness increased from 0 dB at 15 Hz up to a maximum of about 4 dB at 810 Hz. Thus, the mid-bandwidth loudness depression is also observed for hearing-impaired listeners. PMID:27250129

  17. Adaptive Data Filtering of Inertial Sensors with Variable Bandwidth

    PubMed Central

    Alam, Mushfiqul; Rohac, Jan

    2015-01-01

    MEMS (micro-electro-mechanical system)-based inertial sensors, i.e., accelerometers and angular rate sensors, are commonly used as a cost-effective solution for the purposes of navigation in a broad spectrum of terrestrial and aerospace applications. These tri-axial inertial sensors form an inertial measurement unit (IMU), which is a core unit of navigation systems. Even if MEMS sensors have an advantage in their size, cost, weight and power consumption, they suffer from bias instability, noisy output and insufficient resolution. Furthermore, the sensor's behavior can be significantly affected by strong vibration when it operates in harsh environments. All of these constitute conditions require treatment through data processing. As long as the navigation solution is primarily based on using only inertial data, this paper proposes a novel concept in adaptive data pre-processing by using a variable bandwidth filtering. This approach utilizes sinusoidal estimation to continuously adapt the filtering bandwidth of the accelerometer's data in order to reduce the effects of vibration and sensor noise before attitude estimation is processed. Low frequency vibration generally limits the conditions under which the accelerometers can be used to aid the attitude estimation process, which is primarily based on angular rate data and, thus, decreases its accuracy. In contrast, the proposed pre-processing technique enables using accelerometers as an aiding source by effective data smoothing, even when they are affected by low frequency vibration. Verification of the proposed concept is performed on simulation and real-flight data obtained on an ultra-light aircraft. The results of both types of experiments confirm the suitability of the concept for inertial data pre-processing. PMID:25648711

  18. A Wide Bandwidth Digital Recording System for Pulsar Astronomy

    NASA Astrophysics Data System (ADS)

    Jenet, F. A.; Unwin, S. C.; Prince, T. A.

    1995-12-01

    We have developed a powerful and flexible data acquisition system for pulsar astronomy, based on a 50 Mbyte/s commercial instrumentation tape recorder and a custom analog-digital VLSI digitizer chip. This system converts the problem of pulsar detection from largely hardware-oriented to mostly software-oriented. We are using the 512-node Intel Paragon XPS and Touchstone Delta supercomputers at Caltech for pulsar searching and analysis. The detection of fast pulsars requires (1) rapid time sampling, and (2) the ability to correct for dispersion (frequency-dependent time delay caused by charged particles in the interstellar medium). A conventional hardware approach involves a filterbank or correlator at the telescope, then sampling and recording the detected power. Our telescope hardware is relatively simple, performing only downconversion from RF or IF to baseband, followed by Nyquist sampling and (2-bit) digitizing the voltage signal by the custom VLSI chip, then storage on ANSI D1 videocassette. One D1-L cassette allows continuous recording of two polarizations each with 50 MHz bandwidth for 32 minutes, or 25 MHz for 64 minutes. In software we can de-disperse the pulse signals by synthesizing a filterbank with an arbitrary number of frequency channels. Coherent dedispersion can be performed on the voltage (but not power) data, allowing time resolutions down to the inverse RF bandwidth to be achieved in principle. We present first results from observations in July 1995 at the 64-m telescope at Parkes Observatory, Australia Telescope National Facility. These results on known pulsars, including faint globular cluster millisecond-period pulsars, demonstrate the capabilities of our data recording and analysis system.

  19. Adaptive data filtering of inertial sensors with variable bandwidth.

    PubMed

    Alam, Mushfiqul; Rohac, Jan

    2015-01-01

    MEMS (micro-electro-mechanical system)-based inertial sensors, i.e., accelerometers and angular rate sensors, are commonly used as a cost-effective solution for the purposes of navigation in a broad spectrum of terrestrial and aerospace applications. These tri-axial inertial sensors form an inertial measurement unit (IMU), which is a core unit of navigation systems. Even if MEMS sensors have an advantage in their size, cost, weight and power consumption, they suffer from bias instability, noisy output and insufficient resolution. Furthermore, the sensor's behavior can be significantly affected by strong vibration when it operates in harsh environments. All of these constitute conditions require treatment through data processing. As long as the navigation solution is primarily based on using only inertial data, this paper proposes a novel concept in adaptive data pre-processing by using a variable bandwidth filtering. This approach utilizes sinusoidal estimation to continuously adapt the filtering bandwidth of the accelerometer's data in order to reduce the effects of vibration and sensor noise before attitude estimation is processed. Low frequency vibration generally limits the conditions under which the accelerometers can be used to aid the attitude estimation process, which is primarily based on angular rate data and, thus, decreases its accuracy. In contrast, the proposed pre-processing technique enables using accelerometers as an aiding source by effective data smoothing, even when they are affected by low frequency vibration. Verification of the proposed concept is performed on simulation and real-flight data obtained on an ultra-light aircraft. The results of both types of experiments confirm the suitability of the concept for inertial data pre-processing. PMID:25648711

  20. Bandwidth efficient CCSDS coding standard proposals

    NASA Technical Reports Server (NTRS)

    Costello, Daniel J., Jr.; Perez, Lance C.; Wang, Fu-Quan

    1992-01-01

    The basic concatenated coding system for the space telemetry channel consists of a Reed-Solomon (RS) outer code, a symbol interleaver/deinterleaver, and a bandwidth efficient trellis inner code. A block diagram of this configuration is shown. The system may operate with or without the outer code and interleaver. In this recommendation, the outer code remains the (255,223) RS code over GF(2 exp 8) with an error correcting capability of t = 16 eight bit symbols. This code's excellent performance and the existence of fast, cost effective, decoders justify its continued use. The purpose of the interleaver/deinterleaver is to distribute burst errors out of the inner decoder over multiple codewords of the outer code. This utilizes the error correcting capability of the outer code more efficiently and reduces the probability of an RS decoder failure. Since the space telemetry channel is not considered bursty, the required interleaving depth is primarily a function of the inner decoding method. A diagram of an interleaver with depth 4 that is compatible with the (255,223) RS code is shown. Specific interleaver requirements are discussed after the inner code recommendations.

  1. Schottky Heterodyne Receivers With Full Waveguide Bandwidth

    NASA Technical Reports Server (NTRS)

    Hesler, Jeffrey; Crowe, Thomas

    2011-01-01

    Compact THz receivers with broad bandwidth and low noise have been developed for the frequency range from 100 GHz to 1 THz. These receivers meet the requirements for high-resolution spectroscopic studies of planetary atmospheres (including the Earth s) from spacecraft, as well as airborne and balloon platforms. The ongoing research is significant not only for the development of Schottky mixers, but also for the creation of a receiver system, including the LO chain. The new receivers meet the goals of high sensitivity, compact size, low total power requirement, and operation across complete waveguide bands. The exceptional performance makes these receivers ideal for the broader range of scientific and commercial applications. These include the extension of sophisticated test and measurement equipment to 1 THz and the development of low-cost imaging systems for security applications and industrial process monitoring. As a particular example, a WR-1.9SHM (400-600 GHz) has been developed (see Figure 1), with state-of-the-art noise temperature ranging from 1,000-1,800 K (DSB) over the full waveguide band. Also, a Vector Network Analyzer extender has been developed (see Figure 2) for the WR1.5 waveguide band (500 750 GHz) with 100-dB dynamic range.

  2. Bandwidth efficient CCSDS coding standard proposals

    NASA Astrophysics Data System (ADS)

    Costello, Daniel J., Jr.; Perez, Lance C.; Wang, Fu-Quan

    1992-05-01

    The basic concatenated coding system for the space telemetry channel consists of a Reed-Solomon (RS) outer code, a symbol interleaver/deinterleaver, and a bandwidth efficient trellis inner code. A block diagram of this configuration is shown. The system may operate with or without the outer code and interleaver. In this recommendation, the outer code remains the (255,223) RS code over GF(2 exp 8) with an error correcting capability of t = 16 eight bit symbols. This code's excellent performance and the existence of fast, cost effective, decoders justify its continued use. The purpose of the interleaver/deinterleaver is to distribute burst errors out of the inner decoder over multiple codewords of the outer code. This utilizes the error correcting capability of the outer code more efficiently and reduces the probability of an RS decoder failure. Since the space telemetry channel is not considered bursty, the required interleaving depth is primarily a function of the inner decoding method. A diagram of an interleaver with depth 4 that is compatible with the (255,223) RS code is shown. Specific interleaver requirements are discussed after the inner code recommendations.

  3. Remote driving with reduced bandwidth communication

    SciTech Connect

    DePiero, F.W.; Noell, T.E.; Gee, T.F.

    1992-08-06

    Oak Ridge National Laboratory has developed a real-time video transmission system for lowbandwidth remote operations. The system supports both continuous transmission of video for remote driving and progressive transmission of still images. Inherent in the system design is a spatiotemporal limitation to the effects of channel errors. The average data rate of the system is 64,000 bits/s, a compression of approximately 1000:1 for the black and white National Television Standard Code video. The image quality of the transmissions is maintained at a level that supports teleoperation of a high-mobility multipurpose wheeled vehicle at speeds up to 15 mph on a moguled dirt track. Video compression is achieved by using Laplacian image pyramids and a combination of classical techniques. Certain subbands of the image pyramid are transmitted by using interframe differencing with a periodic refresh to aid in bandwidth reduction. Images are also foveated to concentrate image detail in a steerable region. The system supports dynamic video quality adjustments between frame rate, image detail, and foveation rate. A typical configuration for the system used during driving has a frame rate of{approx}4 Hz, a compression per frame of {approx}125:1, and a resulting latency of < 1s.

  4. Pediatric deceased donor renal transplantation: An approach to decision making II. Acceptability of a deceased donor kidney for a child, a snap decision at 3 AM.

    PubMed

    Chaudhuri, Abanti; Gallo, Amy; Grimm, Paul

    2015-11-01

    Allocation of deceased donor kidneys is based on several criteria; however, the final decision to accept or reject the offered kidney is made by the potential recipient's transplant team (surgeon/nephrologist). Several considerations including assessment of the donor quality, the HLA match between the donor and the recipient, several recipient factors, the geographical location of the recipient, and the organ all affect the decision of whether or not to finally accept the organ for a particular recipient. This decision needs to be made quickly, often on the spot. Maximizing the benefit from this scarce resource raises difficult ethical issues. The philosophies of equity and utility are often competing. This article will discuss the several considerations for the pediatric nephrologist while accepting a deceased donor kidney for a particular pediatric patient. PMID:26426405

  5. Note: Expanding the bandwidth of the ultra-low current amplifier using an artificial negative capacitor.

    PubMed

    Xie, Kai; Liu, Yan; Li, XiaoPing; Guo, Lixin; Zhang, Hanlu

    2016-04-01

    The bandwidth and low noise characteristics are often contradictory in ultra-low current amplifier, because an inevitable parasitic capacitance is paralleled with the high value feedback resistor. In order to expand the amplifier's bandwidth, a novel approach was proposed by introducing an artificial negative capacitor to cancel the parasitic capacitance. The theory of the negative capacitance and the performance of the improved amplifier circuit with the negative capacitor are presented in this manuscript. The test was conducted by modifying an ultra-low current amplifier with a trans-impedance gain of 50 GΩ. The results show that the maximum bandwidth was expanded from 18.7 Hz to 3.3 kHz with more than 150 times of increase when the parasitic capacitance (∼0.17 pF) was cancelled. Meanwhile, the rise time decreased from 18.7 ms to 0.26 ms with no overshot. Any desired bandwidth or rise time within these ranges can be obtained by adjusting the ratio of cancellation of the parasitic and negative capacitance. This approach is especially suitable for the demand of rapid response to weak current, such as transient ion-beam detector, mass spectrometry analysis, and fast scanning microscope. PMID:27131718

  6. Note: Expanding the bandwidth of the ultra-low current amplifier using an artificial negative capacitor

    NASA Astrophysics Data System (ADS)

    Xie, Kai; Liu, Yan; Li, XiaoPing; Guo, Lixin; Zhang, Hanlu

    2016-04-01

    The bandwidth and low noise characteristics are often contradictory in ultra-low current amplifier, because an inevitable parasitic capacitance is paralleled with the high value feedback resistor. In order to expand the amplifier's bandwidth, a novel approach was proposed by introducing an artificial negative capacitor to cancel the parasitic capacitance. The theory of the negative capacitance and the performance of the improved amplifier circuit with the negative capacitor are presented in this manuscript. The test was conducted by modifying an ultra-low current amplifier with a trans-impedance gain of 50 GΩ. The results show that the maximum bandwidth was expanded from 18.7 Hz to 3.3 kHz with more than 150 times of increase when the parasitic capacitance (˜0.17 pF) was cancelled. Meanwhile, the rise time decreased from 18.7 ms to 0.26 ms with no overshot. Any desired bandwidth or rise time within these ranges can be obtained by adjusting the ratio of cancellation of the parasitic and negative capacitance. This approach is especially suitable for the demand of rapid response to weak current, such as transient ion-beam detector, mass spectrometry analysis, and fast scanning microscope.

  7. 47 CFR 74.535 - Emission and bandwidth.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Emission and bandwidth. 74.535 Section 74.535 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Aural Broadcast Auxiliary Stations § 74.535 Emission and bandwidth....

  8. 47 CFR 101.515 - Emissions and bandwidth.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Emissions and bandwidth. 101.515 Section 101... FIXED MICROWAVE SERVICES 24 GHz Service and Digital Electronic Message Service § 101.515 Emissions and bandwidth. Different types of emissions may be authorized if the applicant describes fully the...

  9. 47 CFR 2.1049 - Measurements required: Occupied bandwidth.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... established at the frequency of maximum response of the audio modulating circuit. (2) Single sideband....1049 Section 2.1049 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS... Certification § 2.1049 Measurements required: Occupied bandwidth. The occupied bandwidth, that is the...

  10. 47 CFR 2.1049 - Measurements required: Occupied bandwidth.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... established at the frequency of maximum response of the audio modulating circuit. (2) Single sideband....1049 Section 2.1049 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS... Certification § 2.1049 Measurements required: Occupied bandwidth. The occupied bandwidth, that is the...

  11. Continuous control of phase-locked-loop bandwidth

    NASA Technical Reports Server (NTRS)

    Motal, G. W.; Vanelli, J. C.

    1980-01-01

    Tracking loop filter with continuous bandwidth control smooths transition from wide to narrow band. Circuit was designed for Space Shuttle where bandwidth varied between 320 Hz for acquisition and 20 Hz for tracking. Field-effect transitor (FET) acts as voltage controlled variable resistance, changing time constant of filter between phase detector and voltage-controlled oscillator in phase-locked loop.

  12. 47 CFR 101.809 - Bandwidth and emission limitations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Bandwidth and emission limitations. 101.809 Section 101.809 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Local Television Transmission Service § 101.809 Bandwidth and...

  13. 47 CFR 101.809 - Bandwidth and emission limitations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Bandwidth and emission limitations. 101.809 Section 101.809 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Local Television Transmission Service § 101.809 Bandwidth and...

  14. Optimal Bandwidth Selection in Observed-Score Kernel Equating

    ERIC Educational Resources Information Center

    Häggström, Jenny; Wiberg, Marie

    2014-01-01

    The selection of bandwidth in kernel equating is important because it has a direct impact on the equated test scores. The aim of this article is to examine the use of double smoothing when selecting bandwidths in kernel equating and to compare double smoothing with the commonly used penalty method. This comparison was made using both an equivalent…

  15. 47 CFR 101.809 - Bandwidth and emission limitations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Bandwidth and emission limitations. 101.809 Section 101.809 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Local Television Transmission Service § 101.809 Bandwidth and...

  16. 47 CFR 101.809 - Bandwidth and emission limitations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Bandwidth and emission limitations. 101.809 Section 101.809 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Local Television Transmission Service § 101.809 Bandwidth and...

  17. 47 CFR 101.809 - Bandwidth and emission limitations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Bandwidth and emission limitations. 101.809 Section 101.809 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Local Television Transmission Service § 101.809 Bandwidth and...

  18. Matrix bandwidth and profile reduction. [computer programs/permutations

    NASA Technical Reports Server (NTRS)

    Crane, H. L., Jr.; Gibbs, N. E.; Poole, W. G., Jr.; Stockmeyer, P. K.

    1975-01-01

    This program, REDUCE, reduces the bandwidth and profile of sparse symmetric matrices, using row and corresponding column permutations. It is a realization of the algorithm described by the authors elsewhere. It was extensively tested and compared with several other programs and was found to be considerably faster than the others, superior for bandwidth reduction and as satisfactory as any other for profile reduction.

  19. 47 CFR 15.35 - Measurement detector functions and bandwidths.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Measurement detector functions and bandwidths. 15.35 Section 15.35 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY DEVICES General § 15.35 Measurement detector functions and bandwidths. The conducted and radiated emission limits shown in this part are based on...

  20. Clinical Considerations in Using Mindfulness- and Acceptance-Based Approaches With Diverse Populations: Addressing Challenges in Service Delivery in Diverse Community Settings

    ERIC Educational Resources Information Center

    Sobczak, LaTanya Rucker; West, Lindsey M.

    2013-01-01

    Mindfulness- and acceptance-based strategies effectively alter clients' relationships with their internal experiences, which may have been previously restricted, avoided, or even beyond clients' awareness. Even though the scientific exploration of the psychological benefits of mindfulness in the treatment literature continues to be in its infancy,…

  1. The effect of bandwidth on telerobot system performance

    NASA Technical Reports Server (NTRS)

    Uebel, Mark; Ali, Michael S.; Minis, Ioannis

    1991-01-01

    The purpose of the experiment was to determine the effect that various slave-joint bandwidths have on telerobot system performance. The telerobot system consisted of a slave arm controlled by a master. The slave incorporated an impedance loop to provide local compliance in addition to the compliance provided by the operator via force feedback. Three joint bandwidths, 0.5, 1.0, and 2.0 Hz, were used. The performance measures were the task completion time and the sums of the squared forces and moments exerted on the environment. The task consisted of peg-in-hole insertion and removal. The results of the experiment indicate a significant performance decrease at 0.5-Hz bandwidth relative to the 1- and 2-Hz bandwidths. There was no significant change in performance between the 1- and 2-Hz bandwidths.

  2. The effect of stimulus bandwidth on binaural loudness summation.

    PubMed

    Shao, Zhiyue; Mo, Fangshuo; Mao, Dongxing

    2015-09-01

    Binaural loudness summation is an important property of the human auditory system. This paper presents an experimental investigation of how binaural loudness summation varies with stimulus bandwidth. Loudness matches were obtained between dichotic stimuli, with interaural level differences (ILDs) of 2-12 dB, and diotic stimuli. The stimuli were noise bands with seven center frequencies and four bandwidths. Results showed that the loudness of dichotic stimuli increased nonlinearly with ILD, the increase being slightly less with broader bandwidths. There was a bandwidth-dependent difference between the listening tests results and the predictions of Moore and Glasberg's [(2007) J. Acoust. Soc. Am. 121, 1604-1612] loudness model. The size of the difference was, however, small. A characteristic function was derived describing how overall loudness depends on stimulus bandwidth and ILD. PMID:26428788

  3. Evaluation of the acceptability of improved supplementary foods for the treatment of moderate acute malnutrition in Burkina Faso using a mixed method approach.

    PubMed

    Iuel-Brockdorf, Ann-Sophie; Draebel, Tania Aase; Ritz, Christian; Fabiansen, Christian; Cichon, Bernardette; Brix Christensen, Vibeke; Yameogo, Charles; Oummani, Rouafi; Briend, André; Michaelsen, Kim F; Ashorn, Per; Filteau, Suzanne; Friis, Henrik

    2016-04-01

    The objective of this study was to evaluate, within the context of a randomized controlled trial of product effectiveness, the acceptability of new formulations of six corn-soy blended flours (CSB) and six lipid-based nutrient supplements (LNS) with different quantities of milk and qualities of soy for the treatment of children with moderate acute malnutrition (MAM). Our study included 1546 children aged 6-23 months and involved questionnaires after one month of supplementation home visits and interviews with a sub-sample of 20 trial participants and their caretakers, and nine focus group discussion. All 12 products were well accepted in terms of organoleptic qualities and received good ratings. However, LNS were more appreciated by caretakers and children. Additionally, an effect of soy isolate was detected on child appreciation where products with high milk content also received better ratings. CSB were not consumed as readily; 33.9% (n = 257) of children receiving CSB were reported to have leftovers compared to 17.3% (n = 134) of children receiving LNS (p=<0.001). Both CSB and LNS were referred to as foods with medicinal properties and perceived as beneficial to child health. They were both reported to have high priority in the daily feeding of the child. In conclusion, there were minimal differences in acceptability of the various CSB and LNS formulations, although CSB were less readily consumed and required smaller meal volumes. Since all products were well-accepted, decisions regarding whether the more expensive products should be used for the treatment of MAM will need to be based on their effect on child nutrition, growth and health. Future supplementary feeding programs in similar contexts could furthermore consider introducing supplementary foods as a medical treatment, as this may increase adherence and decrease sharing. PMID:26752599

  4. An Extremely Wide Bandwidth, Low Noise SIS Heterodyne Receiver Design for Millimeter and Submillimeter Observations

    NASA Technical Reports Server (NTRS)

    Zmuidzinas, J.

    2004-01-01

    Our group has designed a heterodyne submillimeter receiver that offers a very wide IF bandwidth of 12 GHz, while still maintaining a low noise temperature. The 180-300 GHz double-sideband design uses a single SI5 device excited by a full bandwidth, fixed-tuned waveguide probe on a silicon substrate. The IF output frequency (limited by the MMIC low noise IF preamplifier) is 6-18 GHz. providing an instantaneous RF bandwidth of 24 GHz (double-sideband). Intensive simulations predict that the junction will achieve a conversion loss better than 1-2 dB and a mixer noise temperature of less than 20 K across the band (twice the quantum limit). The single sideband receiver noise temperature goal is 70 K. The wide instantaneous bandwidth and low noise will result in an instrument capable of a variety of important astrophysical and environmental observations beyond the capabilities of current instruments. Lab testing of the receiver will begin this summer, and first light on the CSO should be in the Spring of 2003. At the CSO, we plan to use receiver with WASP2, a wideband spectrometer, to search for spectral lines from SCUBA sources. This approach should allow us to rapidly develop a catalog of redshifts for these objects.

  5. Phase locking and bandwidth in a gyrotron oscillator

    NASA Technical Reports Server (NTRS)

    Latham, P. E.; Granatstein, V. L.; Carmel, Y.

    1993-01-01

    For imaging radar and for satellite and space communication (e.g. NASA's deep space network), it is important that the bandwidth be as large as possible. Here we derive a formalism for computing the phase locking bandwidth that can be achieved in a gyrotron oscillator while varying the beam voltage. As an example, a second harmonic TE02/03 gyrotron is considered. For this device, the effective bandwidth can be increased by a factor of about 3 compared with the fixed voltage case by allowing the beam voltage to change together with the input locking signal.

  6. Microwave photonic bandstop filter with wide tunability and adjustable bandwidth.

    PubMed

    Li, Wei; Yang, Chengwu; Wang, Ling; Yuan, Zhilin; Liu, Jianguo; Li, Ming; Zhu, Ninghua

    2015-12-28

    A microwave photonic bandstop filter is proposed and experimentally demonstrated in this work. The filter exhibits promising performance combination of reconfigurability, frequency tunability, and bandwidth adjustment. The phase modulation on two orthogonal polarization states produces a bandpass and a lowpass MPF, respectively. The key concept of destructive interference between the bandpass and lowpass MPF enables the reconfiguration of MPF from bandpass to bandstop. By adjusting the wavelength of two orthogonally polarized optical carriers and the bandwidth of an optical bandpass filter, the bandstop filter is tunable in terms of center frequency and bandwidth. PMID:26832021

  7. Bandwidth auction for SVC streaming in dynamic multi-overlay

    NASA Astrophysics Data System (ADS)

    Xiong, Yanting; Zou, Junni; Xiong, Hongkai

    2010-07-01

    In this paper, we study the optimal bandwidth allocation for scalable video coding (SVC) streaming in multiple overlays. We model the whole bandwidth request and distribution process as a set of decentralized auction games between the competing peers. For the upstream peer, a bandwidth allocation mechanism is introduced to maximize the aggregate revenue. For the downstream peer, a dynamic bidding strategy is proposed. It achieves maximum utility and efficient resource usage by collaborating with a content-aware layer dropping/adding strategy. Also, the convergence of the proposed auction games is theoretically proved. Experimental results show that the auction strategies can adapt to dynamic join of competing peers and video layers.

  8. Finite mass enhancement across bandwidth controlled Mott transition in NiS2-xSex

    NASA Astrophysics Data System (ADS)

    Han, Garam; Kyung, W. S.; Kim, Y. K.; Cheng, C. M.; Tsuei, K. D.; Lee, K. D.; Hur, N.; Kim, H.-D.; Kim, C.

    One of the most important and still debated issues in the strongly correlated electron systems is on the metal insulator transition (MIT) mechanism. In the bandwidth controlled Mott transition (BCMT) scenario, which Mott originally proposed, MIT occurs through a mass divergence in which the effective mass of the quasi-particle (QP) diverges approaching the MIT. The interpretation is supported by dynamic mean field theory (DMFT) model calculations. However, few direct observations have been made yet due to various experimental restrictions. In this talk, I present systematic angle resolved photoemission studies on the MIT in NiS2-xSex, which is a well-known BCMT material. We observed not only the bandwidth shrinkage but also the coherent quasi-particle peak (QP) which is not of the surface origin. In addition, we experimentally showed the mass of the QP remains finite approaching the MIT. This work was supported by IBS-R009-D1.

  9. Simulations of the intermediate bandwidth fluctuations in nanostructured PV

    NASA Astrophysics Data System (ADS)

    Mebadi, Ashkan; Houshmand, Mohammad; Zandi, M. Hossein; Gorji, Nima E.

    2013-09-01

    The size dispersion and distributions of quantum dot nanoparticles (sizes from 2-5 nm) embedded in the active region of the intermediate band solar cells are important to reach the high efficiencies. An optimized size and regularity can increase the efficiency due largely to avoided non-radiative transitions which can originate from the fluctuations in the bandwidth of the intermediate layer. In this work, we propose all the energy band diagrams possible in the formation of such a cell. Five equivalent band diagrams of the cells with different size dispersions and regularity of quantum dots are considered and compared with the reported experimental profiles in the literature. Furthermore, the degree of the size fluctuation is considered by proposing a fluctuation degree for the band gap and sub-band gaps of the cell. These proposed profiles and the fluctuation theory are exploited to consider the experimental data reported in literature. The optimized size dispersion will increase the photocurrent of the cell. We believe that every quantum dot solar cell will fall into one of the proposed band diagrams. This approach gives foresight to the theoretical studies of such devices and expectation from the energy band structure and band widths since it considers the fluctuation of the band widths for the intermediate band separately.

  10. 47 CFR 74.736 - Emissions and bandwidth.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.736 Emissions and bandwidth. (a) The license of a low power TV, TV translator, or...

  11. 47 CFR 74.736 - Emissions and bandwidth.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.736 Emissions and bandwidth. (a) The license of a low power TV, TV translator, or...

  12. 47 CFR 74.736 - Emissions and bandwidth.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.736 Emissions and bandwidth. (a) The license of a low power TV, TV translator, or...

  13. 47 CFR 74.736 - Emissions and bandwidth.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.736 Emissions and bandwidth. (a) The license of a low power TV, TV translator, or...

  14. 47 CFR 74.736 - Emissions and bandwidth.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.736 Emissions and bandwidth. (a) The license of a low power TV, TV translator, or...

  15. Increase of the grating coupler bandwidth with a graphene overlay

    SciTech Connect

    Cheng, Zhenzhou; Li, Zhen; Xu, Ke; Tsang, Hon Ki

    2014-03-17

    We present theoretical and experimental results that demonstrate an increase in the grating bandwidth by placing a graphene on the chip. A focusing subwavelength grating with coupling efficiency of −4.3 dB and 1 dB bandwidth of ∼60 nm was demonstrated. After a graphene sheet was transferred onto the chip, the maximum 1 dB bandwidth was increased to ∼72 nm. Experimental results are consistent with the calculated graphene induced waveguide refractive index and dispersion changes, and the bandwidth improvement may be attributed to the reduction of grating dispersion. This study may be of interest for graphene-on-silicon photonic integrated circuit applications.

  16. Bandwidth efficient coherent lidar based on phase-diversity detection.

    PubMed

    Liao, Tongqing; Hameed, Mahmood; Hui, Rongqing

    2015-04-10

    Bandwidth efficient coherent lidar based on phase-diversity detection is reported for the first time, to the best of our knowledge, which allows the doubling of bandwidth efficiency through the simultaneous utilization of the in-phase (I) and quadrature (Q) components. By maintaining RF phase continuity between linearly frequency-chirped I and Q components through digital signal processing, the range resolution of the lidar system can be improved. PMID:25967299

  17. Improved bandwidth of microstrip antennas using parasitic elements

    NASA Astrophysics Data System (ADS)

    Wood, C.

    1980-08-01

    A method is described of doubling the bandwidth of rectangular microstrip patch antennas by locating capacitively excited m-wavelength/4 short circuit parasitic elements at their radiating edges. The antenna characteristics are explained in terms of an antiphase mode of a pair of coupled resonators, and it is shown that the bandwidth improvement is independent of the coupling capacitance. Experimental results are presented for both linearly and circularly polarized antennas which support the theoretical predictions.

  18. Optical parametric amplification with a bandwidth exceeding an octave

    SciTech Connect

    Orlov, Sergei N; Polivanov, Yurii N; Pestryakov, Efim V

    2004-05-31

    The possibility of using various schemes of broadband optical parametric amplifiers (OPAs) for amplifying a supercontinuum with the spectral bandwidth exceeding an octave is analysed. Spectral gain profiles are calculated for some specific OPAs employing promising and available nonlinear optical crystals. The realisation of OPAs with spectral bandwidths exceeding an octave in the spectral region from the near-UV to the mid-IR is demonstrated by specific examples. (nonlinear optical phenomena)

  19. Bandwidth control of wavelength-selective uncooled infrared sensors using two-dimensional plasmonic absorbers

    NASA Astrophysics Data System (ADS)

    Ogawa, Shinpei; Fujisawa, Daisuke; Kimata, Masafumi

    2016-05-01

    Although standard uncooled infrared (IR) sensors can be used to record information such as the shape, position, and average radiant intensity of objects, these devices cannot capture color (that is, wavelength) data. Achieving wavelength selectivity would pave the way for the development of advanced uncooled IR sensors capable of providing color information as well as multi-color image sensors that would have significant advantages in applications such as fire detection, gas analysis, hazardous material recognition, and biological analysis. We have previously demonstrated an uncooled IR sensor incorporating a two-dimensional plasmonic absorber (2D PLA) that exhibits wavelength selectivity over a wide range in the mid- and long-IR regions. This PLA has a 2D Au-based periodic array of dimples, in which surface plasmon modes are induced and wavelength-selective absorption occurs. However, the dependence of the absorption bandwidth on certain structural parameters has yet to be clarified. The bandwidth of such devices is a vital factor when considering the practical application of these sensors to tasks such as gas detection. In the present study, control of the bandwidth was theoretically investigated using a rigorous coupled wave analysis approach. It is demonstrated that the dimple sidewall structure has a significant impact on the bandwidth and can be used to control both narrow- and broadband absorption. Increasing the sidewall slope was found to decrease the bandwidth due to suppression of cavity-mode resonance in the depth direction of the dimples. These results will contribute to the development of high-resolution, wavelength-selective uncooled IR sensors.

  20. Malpositioned implants in the anterior maxilla: a novel restorative approach to reestablish peri-implant tissue health and acceptable esthetics. Part II: Case report and discussion.

    PubMed

    Moráguez, Osvaldo D; Vailati, Francesca; Belser, Urs C

    2015-01-01

    This two-part case presentation describes the prosthetic challenge of managing complications in a 50-year-old female patient after inadequate esthetic risk assessment, treatment planning, and implant placement in the anterior maxilla. In Part I, the clinical situation was described, and different restorative solutions were proposed to correct the extreme facial inclination of the implants, excluding major surgical procedures, namely implant removal. In Part II, different prosthetic options are discussed, and the final treatment is revealed. A noninvasive treatment protocol was applied to transform a severely compromised postsurgical situation into an esthetically acceptable result. An unconventional prosthesis design was implemented, including the use of ceramic veneers bonded to the CAD/CAM-generated screw-retained zirconia- based fixed dental prosthesis (FDP), to correct major axis-related problems and spatial discrepancies. PMID:26794049

  1. A Synthetic Bandwidth Method for High-Resolution SAR Based on PGA in the Range Dimension

    PubMed Central

    Li, Jincheng; Chen, Jie; Liu, Wei; Wang, Pengbo; Li, Chunsheng

    2015-01-01

    The synthetic bandwidth technique is an effective method to achieve ultra-high range resolution in an SAR system. There are mainly two challenges in its implementation. The first one is the estimation and compensation of system errors, such as the timing deviation and the amplitude-phase error. Due to precision limitation of the radar instrument, construction of the sub-band signals becomes much more complicated with these errors. The second challenge lies in the combination method, that is how to fit the sub-band signals together into a much wider bandwidth. In this paper, a novel synthetic bandwidth approach is presented. It considers two main errors of the multi-sub-band SAR system and compensates them by a two-order PGA (phase gradient auto-focus)-based method, named TRPGA. Furthermore, an improved cut-paste method is proposed to combine the signals in the frequency domain. It exploits the redundancy of errors and requires only a limited amount of data in the azimuth direction for error estimation. Moreover, the up-sampling operation can be avoided in the combination process. Imaging results based on both simulated and real data are presented to validate the proposed approach. PMID:26131679

  2. A Synthetic Bandwidth Method for High-Resolution SAR Based on PGA in the Range Dimension.

    PubMed

    Li, Jincheng; Chen, Jie; Liu, Wei; Wang, Pengbo; Li, Chunsheng

    2015-01-01

    The synthetic bandwidth technique is an effective method to achieve ultra-high range resolution in an SAR system. There are mainly two challenges in its implementation. The first one is the estimation and compensation of system errors, such as the timing deviation and the amplitude-phase error. Due to precision limitation of the radar instrument, construction of the sub-band signals becomes much more complicated with these errors. The second challenge lies in the combination method, that is how to fit the sub-band signals together into a much wider bandwidth. In this paper, a novel synthetic bandwidth approach is presented. It considers two main errors of the multi-sub-band SAR system and compensates them by a two-order PGA (phase gradient auto-focus)-based method, named TRPGA. Furthermore, an improved cut-paste method is proposed to combine the signals in the frequency domain. It exploits the redundancy of errors and requires only a limited amount of data in the azimuth direction for error estimation. Moreover, the up-sampling operation can be avoided in the combination process. Imaging results based on both simulated and real data are presented to validate the proposed approach. PMID:26131679

  3. Banded all-optical OFDM super-channels with low-bandwidth receivers.

    PubMed

    Song, Binhuang; Zhu, Chen; Corcoran, Bill; Zhuang, Leimeng; Lowery, Arthur James

    2016-08-01

    We propose a banded all-optical orthogonal frequency division multiplexing (AO-OFDM) transmission system based on synthesising a number of truncated sinc-shaped subcarriers for each sub-band. This approach enables sub-band by sub-band reception and therefore each receiver's electrical bandwidth can be significantly reduced compared with a conventional AO-OFDM system. As a proof-of-concept experiment, we synthesise 6 × 10-Gbaud subcarriers in both conventional and banded AO-OFDM systems. With a limited receiver electrical bandwidth, the experimental banded AO-OFDM system shows 2-dB optical signal to noise ratio (OSNR) benefit over conventional AO-OFDM at the 7%-overhead forward error correction (FEC) threshold. After transmission over 800-km of single-mode fiber, ≈3-dB improvement in Q-factor can be achieved at the optimal launch power at a cost of increasing the spectral width by 14%. PMID:27505764

  4. Soliton Solutions for High-Bandwidth Optical Pulse Storage and Retrieval

    NASA Astrophysics Data System (ADS)

    Groves, Elizabeth

    Quantum-optical information processing in material systems requires on-demand manipulation and precision control techniques. Previous implementations of optical pulse control have mostly been limited to weak, narrowband probe fields, often using a modified form of Electromagnetically Induced Transparency (EIT). We propose optical pulse control in a contrasting regime with high-bandwidth optical pulses, enabling higher clock-rates and on-demand fast pulse switching. Our novel solutions exploit the coherent interaction between short, strong pulses and resonant media (such as a cloud of ultra-cold atoms) to store, manipulate, and retrieve high-bandwidth optical pulse information. The evolution equations that model such short pulse propagation are inherently nonlinear and they govern both amplitudes and phases of the propagating field and the dielectric medium. They cannot be modeled by population rate equations or simplified with steady-state assumptions. Nonlinear evolution equations do not yield solutions easily and using them to characterize the physics at hand typically requires complementary analytical and numerical approaches. We take both approaches here, using analytical methods and our own numerical integration code. For uniform and infinitely extended media we generate novel three-pulse soliton solutions: robust, nonlinear waves with the unique property of preserving their shape under interaction (or "collision"). This important property enables one high-bandwidth soliton to push another from one location in an atomic cloud to another, predictably and nondestructively. We then also probe the practical utility of our specialized infinite-extent solutions by numerically solving the same nonlinear evolution equations for a variety of initial pulse shapes and strengths. Our numerical simulations confirm that our novel soliton solutions provide appropriate control parameters, including pulse storage locations and pulse sequencing, even in finite media under non

  5. Broad Bandwidth Laser and Nonlinear Optical Sources for OCT

    NASA Astrophysics Data System (ADS)

    Unterhuber, Angelika; Považay, Boris; Aguirre, Aaron D.; Chen, Yu; Kärtner, Franz X.; Fujimoto, James G.; Drexler, Wolfgang

    OCT achieves very high axial image resolutions independent of focusing conditions because the axial and transverse resolutions are determined independently by different physical mechanisms. This implies that axial OCT resolution can be enhanced using broad bandwidth, low coherence length light sources. The light source not only determines axial OCT resolution via its bandwidth and central emission wavelength but also determines the penetration in the sample (biological tissue), the contrast of the tomogram, and the OCT transverse resolution. A minimum output power with low amplitude noise is also necessary to enable high sensitivity and high-speed - real time - OCT imaging. Hence, it is obvious that the light source is the key technological parameter for an OCT system, and proper choice is imperative. Ultrabroad bandwidth light source technology enables ultrahigh-resolution OCT in the visible and near-infrared wavelength region. Kerr-lens mode-locked solid-state lasers can generate broad bandwidth spectra spanning up to one optical octave. Nonetheless they are restricted to the fluorescence bands of the laser crystal and have a complex architecture making them expensive and preventing widespread industrial use. Spectra far broader than one optical octave can be produced via nonlinear propagation of laser pulses having only moderate energies of a few nJ in microstructured fibers. Complex fibers with one, two, or even no zero-dispersion wavelength can be designed and fabricated to fulfill special requirements as large optical bandwidth and low noise.

  6. Raman-induced slow-light delay of THz-bandwidth pulses

    NASA Astrophysics Data System (ADS)

    Bustard, Philip J.; Heshami, Khabat; England, Duncan G.; Spanner, Michael; Sussman, Benjamin J.

    2016-04-01

    We propose and experimentally demonstrate a scheme to generate optically controlled delays based on off-resonant Raman absorption. Dispersion in a transparency window between two neighboring, optically activated Raman absorption lines is used to reduce the group velocity of broadband 765 nm pulses. We implement this approach in a potassium titanyl phosphate (KTP) waveguide at room temperature, and demonstrate Raman-induced delays of up to 140 fs for a 650-fs duration, 1.8-THz bandwidth, pulse. Our approach should be applicable to single-photon signals, offers wavelength tunability, and is a step toward processing ultrafast photons.

  7. Efficient, designable, and broad-bandwidth optical extinction via aspect-ratio-tailored silver nanodisks

    NASA Astrophysics Data System (ADS)

    Anquillare, E. L.; Miller, O. D.; Hsu, C. W.; DeLacy, B. G.; Joannopoulos, J. D.; Johnson, S. G.; Soljačić, M.

    2016-05-01

    Subwavelength resonators, ranging from single atoms to metallic nanoparticles, typically exhibit a narrow-bandwidth response to optical excitations. We computationally design and experimentally synthesize tailored distributions of silver nanodisks to extinguish light over broad and varied frequency windows. We show that metallic nanodisks are two-to-ten-times more efficient in absorbing and scattering light than common structures, and can approach fundamental limits to broadband scattering for subwavelength particles. We measure broadband extinction per volume that closely approaches theoretical predictions over three representative visible-range wavelength windows, confirming the high efficiency of nanodisks and demonstrating the collective power of computational design and experimental precision for developing new photonics technologies.

  8. Maximum bandwidth snapshot channeled imaging polarimeter with polarization gratings

    NASA Astrophysics Data System (ADS)

    LaCasse, Charles F.; Redman, Brian J.; Kudenov, Michael W.; Craven, Julia M.

    2016-05-01

    Compact snapshot imaging polarimeters have been demonstrated in literature to provide Stokes parameter estimations for spatially varying scenes using polarization gratings. However, the demonstrated system does not employ aggressive modulation frequencies to take full advantage of the bandwidth available to the focal plane array. A snapshot imaging Stokes polarimeter is described and demonstrated through results. The simulation studies the challenges of using a maximum bandwidth configuration for a snapshot polarization grating based polarimeter, such as the fringe contrast attenuation that results from higher modulation frequencies. Similar simulation results are generated and compared for a microgrid polarimeter. Microgrid polarimeters are instruments where pixelated polarizers are superimposed onto a focal plan array, and this is another type of spatially modulated polarimeter, and the most common design uses a 2x2 super pixel of polarizers which maximally uses the available bandwidth of the focal plane array.

  9. Adaptive Broadcasting Mechanism for Bandwidth Allocation in Mobile Services

    PubMed Central

    Horng, Gwo-Jiun; Wang, Chi-Hsuan; Chou, Chih-Lun

    2014-01-01

    This paper proposes a tree-based adaptive broadcasting (TAB) algorithm for data dissemination to improve data access efficiency. The proposed TAB algorithm first constructs a broadcast tree to determine the broadcast frequency of each data and splits the broadcast tree into some broadcast wood to generate the broadcast program. In addition, this paper develops an analytical model to derive the mean access latency of the generated broadcast program. In light of the derived results, both the index channel's bandwidth and the data channel's bandwidth can be optimally allocated to maximize bandwidth utilization. This paper presents experiments to help evaluate the effectiveness of the proposed strategy. From the experimental results, it can be seen that the proposed mechanism is feasible in practice. PMID:25057509

  10. Electromagnetic waves with large relative bandwidth (Invited paper)

    NASA Astrophysics Data System (ADS)

    Harmuth, H. F.

    1985-09-01

    The history of the use of sinusoidal functions and the suitability of these functions for the transmission of information are discussed, taking into account also possibilities for a use of nonsinusoidal functions. It is shown that the available technology is capable of radiating and selectively receiving nonsinusoidal waves. As a basis for an evaluation of the application possibilities for nonsinusoidal electromagnetic waves, attention is given to a concept which makes it possible to distinguish quantitatively between theoretical sinusoidal waves, practical (almost) sinusoidal waves, and nonsinusoidal waves. A suitable measure is provided by the concept of the relative bandwidth. It is pointed out that semiconductor technology has made it possible to use radio signals with large relative bandwidth or nonsinusoidal signals, instead of conventional signals with small relative bandwidth or (almost) sinusoidal signals. The practical level of this new development was reached with the ground-probing radar. Many more applications are possible.

  11. Benefits of Bandwidth Feedback in Learning a Complex Gymnastic Skill

    PubMed Central

    Sadowski, Jerzy; Mastalerz, Andrzej; Niznikowski, Tomasz

    The aim of this study was to examine the effects of two different frequencies of feedback during the process of learning a complex gymnastic skill, the round-off salto backward tucked. Thirty male acrobats participated in the study. They were randomly assigned to two groups: B - bandwidth feedback (n=15) or C - 100% feedback (n=15). Group B was provided with error information regarding the key elements of movement techniques only (bandwidth feedback). Our research demonstrates the advantage of augmented feedback information related to errors in the key elements. Information about errors in the key elements during learning a complex gymnastic skill prevents the gymnast from becoming overwhelmed, which promotes better motor control. These results provide support for the generalisation of bandwidth feedback principles to a complex task. Our research shows that the guidance hypothesis can also be tested in practical settings for a complex movement task. PMID:24146719

  12. Delivery of very high bandwidth with ATM switches and SONET

    SciTech Connect

    Gossage, S.A.

    1993-08-01

    To deliver high bandwidth, a ubiquitous inter-/intra-building cable plant consisting of single mode and multimode fiber as well as twisted pair copper is required. The selection of the ``glue`` to transport and interconnect distributed LANs with central facility resources over a pervasive cable plant is the focus of this paper. A description of the traditional problems that must be overcome to provide very high bandwidth beyond the narrow confines of a computer center is given. The applicability of Asynchronous Transfer Mode (ATM) switching (interconnection) and Synchronous Optical NETwork (SONET) (transport) for high bandwidth delivery is described using the environment and requirements of Sandia National Laboratories. Other methods for distributing high data rates are compared and contrasted. Sandia is implementing a standards based foundation utilizing a pervasive single mode fiber cable plant, SONET transport, and ATM switching to meet the goals of gigabit networking.

  13. A new bandwidth compression system of picture signals - The TAT

    NASA Astrophysics Data System (ADS)

    Tanimoto, M.; Chiba, N.; Yasui, H.; Murakami, M.

    A new bandwidth compression system of picture signals called the Time-Axis Transform (TAT) system is presented. It can be applied to the various fields of transmission and recording of picture signals such as the satellite broadcast of high-definition televison. The TAT compresses the bandwidth by reducing the number of transmitted pixels. The transmitted pixels consist of two kinds of pixels: the basic pixels and the additional pixels. The location of the former is fixed and that of the latter varies from picture to picture to minimize the interpolation error in the reconstructed picture. It compresses the bandwidth of the picture signal to one half or less, keeping high picture quality. Both the average power and the peak value of the distortion due to the interpolation error of the deleted pixels are greatly improved.

  14. Bandwidth analysis of all-optical turbo-switch

    NASA Astrophysics Data System (ADS)

    Zhou, Peng; Yang, Xuelin; Hu, Xiaonan; Hu, Weisheng

    2015-01-01

    We propose and develop a frequency-domain model to analyze the bandwidth of all-optical turbo-switch. The model has taken the spatial inhomogeneity of semiconductor optical amplifier (SOA) into consideration for the first time. The simulations based on the model show that the 3-dB bandwidth of turbo-switch could reach up to ~270 GHz when the second SOA is oversaturated. However, the overshoot will be higher, which may result in the distortion of the output signal. There is a trade-off between the bandwidth and the flatness of frequency response characteristics for turbo-switch operation. In addition, the optimum position of the delay-interferometer (DI) is investigated, showing that the level of the overshoot is relatively lower if the DI is placed between the two SOAs.

  15. Correlation and image compression for limited-bandwidth CCD.

    SciTech Connect

    Thompson, Douglas G.

    2005-07-01

    As radars move to Unmanned Aerial Vehicles with limited-bandwidth data downlinks, the amount of data stored and transmitted with each image becomes more significant. This document gives the results of a study to determine the effect of lossy compression in the image magnitude and phase on Coherent Change Detection (CCD). We examine 44 lossy compression types, plus lossless zlib compression, and test each compression method with over 600 CCD image pairs. We also derive theoretical predictions for the correlation for most of these compression schemes, which compare favorably with the experimental results. We recommend image transmission formats for limited-bandwidth programs having various requirements for CCD, including programs which cannot allow performance degradation and those which have stricter bandwidth requirements at the expense of CCD performance.

  16. Delivery of very high bandwidth with ATM switches and SONET

    SciTech Connect

    Gossage, S.A.

    1992-10-01

    The choice of technologies for the delivery of very high bandwidth throughout a facility capable of ultimately achieving gigabits per second performance, is a crucial one for any high technology facility. The components of a high bandwidth delivery system include high performance sources and sinks in the form of central facilities (major mainframes, large file storage and specialized peripherals) and powerful, full bandwidth distributed local area networks (LANs). In order to deliver bandwidth among the sources and sinks, a ubiquitous inter-/intra-building cable plant consisting of single mode and multimode fiber as well as twisted pair copper is required. The selection of the ``glue`` to transport and interconnect the LANs with the central facility over the pervasive cable plant is the focus of this paper. A design philosophy for high performance communications systems is proposed. A description of the traditional problems that must be overcome to provide very high bandwidth beyond the narrow confines of a computer center is given. The advantages of ATM switching and SONET physical transport are explored in the structured design presentation. The applicability of Asynchronous Transfer Mode (ATM) switching (interconnection) and Synchronous Optical NETwork (SONET) (transport) for high bandwidth delivery is described using the environment and requirements of Sandia National Laboratories as a context to examine the suitability of those technologies. The synergy and utility of ATM and SONET in the campus network are explored. Other methods for distributing high data rates are compared and contrasted to ATM and SONET with respect to cable plant impact, reliability/availability, maintainability, and capacity. Sandia is implementing a standards based foundation utilizing a pervasive single mode fiber cable plant, SONET transport, and ATM switching to meet the goals of gigabit networking.

  17. Ultrafast pulsed laser utilizing broad bandwidth laser glass

    DOEpatents

    Payne, Stephen A.; Hayden, Joseph S.

    1997-01-01

    An ultrafast laser uses a Nd-doped phosphate laser glass characterized by a particularly broad emission bandwidth to generate the shortest possible output pulses. The laser glass is composed primarily of P.sub.2 O.sub.5, Al.sub.2 O.sub.3 and MgO, and possesses physical and thermal properties that are compatible with standard melting and manufacturing methods. The broad bandwidth laser glass can be used in modelocked oscillators as well as in amplifier modules.

  18. TDX: A high-bandwidth crossbar-switched communication paradigm

    SciTech Connect

    Pierce, P.E.; Eilers, D.L.; Schreiber, A.L.

    1994-08-01

    Digital signal processing systems under development today require scalable and reconfigurable high bandwidth communication resources between processing elements. Shared memory architectures require the ability to transfer data from one processor node to another, as well as maintaining data coherency such as provided by the Scalable Coherent Interface (SCI). Signal processing systems that must move large amounts of data between processor nodes, are best served by a communication system that allows reconfigurable streams of data to flow at deterministic rates with minimal overhead. A Time Domain Crossbar (TDX) communication system providing scalable, programmable, high-bandwidth, streaming communication has been developed and is described in this paper.

  19. Ultrafast pulsed laser utilizing broad bandwidth laser glass

    DOEpatents

    Payne, S.A.; Hayden, J.S.

    1997-09-02

    An ultrafast laser uses a Nd-doped phosphate laser glass characterized by a particularly broad emission bandwidth to generate the shortest possible output pulses. The laser glass is composed primarily of P{sub 2}O{sub 5}, Al{sub 2}O{sub 3} and MgO, and possesses physical and thermal properties that are compatible with standard melting and manufacturing methods. The broad bandwidth laser glass can be used in modelocked oscillators as well as in amplifier modules. 7 figs.

  20. Programmable bandwidth management in software-defined EPON architecture

    NASA Astrophysics Data System (ADS)

    Li, Chengjun; Guo, Wei; Wang, Wei; Hu, Weisheng; Xia, Ming

    2016-07-01

    This paper proposes a software-defined EPON architecture which replaces the hardware-implemented DBA module with reprogrammable DBA module. The DBA module allows pluggable bandwidth allocation algorithms among multiple ONUs adaptive to traffic profiles and network states. We also introduce a bandwidth management scheme executed at the controller to manage the customized DBA algorithms for all date queues of ONUs. Our performance investigation verifies the effectiveness of this new EPON architecture, and numerical results show that software-defined EPONs can achieve less traffic delay and provide better support to service differentiation in comparison with traditional EPONs.

  1. Variable bandwidth birefringent filter for tunable femtosecond lasers

    SciTech Connect

    Naganuma, K.; Lenz, G.; Ippen, E.P. )

    1992-10-01

    A design for a birefringent filter is described, which is suitable for tunable femtosecond lasers. Using a single plate, which has a steeply diving optic axis, two-octave tunability is attained with negligible deterioration of the stopband rejection. For a specific wavelength region, it means that the filter's bandwidth can be changed by a factor of four. Another characteristic of the design is that, for the same bandwidth, the proposed plate is five times thicker than a conventional plate in which the optic axis is parallel to the surface. Thus, etalon effects can be avoided. Tuning characteristics of color center lasers utilizing the new filter are also presented. 18 refs.

  2. ATLAS ACCEPTANCE TEST

    SciTech Connect

    J.C. COCHRANE; J.V. PARKER; ET AL

    2001-06-01

    The acceptance test program for Atlas, a 23 MJ pulsed power facility for use in the Los Alamos High Energy Density Hydrodynamics program, has been completed. Completion of this program officially releases Atlas from the construction phase and readies it for experiments. Details of the acceptance test program results and of machine capabilities for experiments will be presented.

  3. Bandwidth provisioning in infrastructure-based wireless networks employing directional antennas

    SciTech Connect

    Hasiviswanthan, Shiva; Zhao, Bo; Vasudevan, Sudarshan; Yrgaonkar, Bhuvan

    2009-01-01

    Motivated by the widespread proliferation of wireless networks employing directional antennas, we study the problem of provisioning bandwidth in such networks. Given a set of subscribers and one or more access points possessing directional antennas, we formalize the problem of orienting these antennas in two fundamental settings: (1) subscriber-centric, where the objective is to fairly allocate bandwidth among the subscribers and (2) provider-centric, where the objective is to maximize the revenue generated by satisfying the bandwidth requirements of subscribers. For both the problems, we first design algorithms for a network with only one access point working under the assumption that the number of antennas does not exceed the number of noninterfering channels. Using the well-regarded lexicographic max-min fair allocation as the objective for a subscriber-centric network, we present an optimum dynamic programming algorithm. For a provider-centric network, the allocation problem turns out to be NP-hard. We present a greedy heuristic based algorithm that guarantees almost half of the optimum revenue. We later enhance both these algorithms to operate in more general networks with multiple access points and no restrictions on the relative numbers of antennas and channels. A simulation-based evaluation using OPNET demonstrates the efficacy of our approaches and provides us further in insights into these problems.

  4. Distributed Vector Estimation for Power- and Bandwidth-Constrained Wireless Sensor Networks

    NASA Astrophysics Data System (ADS)

    Sani, Alireza; Vosoughi, Azadeh

    2016-08-01

    We consider distributed estimation of a Gaussian vector with a linear observation model in an inhomogeneous wireless sensor network, where a fusion center (FC) reconstructs the unknown vector, using a linear estimator. Sensors employ uniform multi-bit quantizers and binary PSK modulation, and communicate with the FC over orthogonal power- and bandwidth-constrained wireless channels. We study transmit power and quantization rate (measured in bits per sensor) allocation schemes that minimize mean-square error (MSE). In particular, we derive two closed-form upper bounds on the MSE, in terms of the optimization parameters and propose coupled and decoupled resource allocation schemes that minimize these bounds. We show that the bounds are good approximations of the simulated MSE and the performance of the proposed schemes approaches the clairvoyant centralized estimation when total transmit power or bandwidth is very large. We study how the power and rate allocation are dependent on sensors observation qualities and channel gains, as well as total transmit power and bandwidth constraints. Our simulations corroborate our analytical results and illustrate the superior performance of the proposed algorithms.

  5. 47 CFR 74.1236 - Emission and bandwidth.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Emission and bandwidth. 74.1236 Section 74.1236 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES FM Broadcast Translator Stations and FM Broadcast Booster Stations...

  6. Numerical Models of Broad Bandwidth Nanosecond Optical Parametric Oscillators

    SciTech Connect

    Bowers, M.S.; Gehr, R.J.; Smith, A.V.

    1998-10-14

    We describe results from three new methods of numerically modeling broad-bandwidth, nanosecond OPO's in the plane-wave approximate ion. They account for differences in group velocities among the three mixing waves, and also include a qutt~ttun noise model.

  7. Bandwidth based electrical-analogue battery modeling for battery modules

    NASA Astrophysics Data System (ADS)

    Li, Jianwei; Mazzola, Michael S.; Gafford, James; Jia, Bin; Xin, Ming

    2012-11-01

    A technique for building a high fidelity electrical-analogue battery model by identifying the model parameters at the module level, as opposed to the cell level, is proposed in this paper. The battery model, which is represented by electrical circuit components, can be easily integrated into popular simulation environments for system level design and predictive analysis. A novel bandwidth based time-domain procedure is introduced for identifying the model parameters by selective assignment of the limited bandwidth of the battery model approximation according to the natural bandwidth of the system that uses the battery. The aim of this paper is to provide an accurate off-line electrical-analogue battery model for simulation of larger systems containing large-format batteries, as opposed to a detailed electrochemical model suitable for simulation of internal battery processes. The proposed procedure has been experimentally verified on a 6.8 Ah Ultralife UBBL10 Li-ion battery module which is a “microcosm” for a modern large-format battery pack. A maximum 0.25% error was observed during a performance test with arbitrary but bandwidth-limited charging and discharging intervals characteristic of a typical battery application.

  8. The Learning Computer: Low Bandwidth Tool that Bridges Digital Divide

    ERIC Educational Resources Information Center

    Johnson, Russell; Kemp, Elizabeth; Kemp, Ray; Blakey, Peter

    2007-01-01

    This article reports on a project that explores strategies for narrowing the digital divide by providing a practicable e-learning option for the millions living outside the ambit of high performance computing and communication technology. The concept is introduced of a "learning computer," a low bandwidth tool that provides a simplified,…

  9. 47 CFR 2.1049 - Measurements required: Occupied bandwidth.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Measurements required: Occupied bandwidth. 2.1049 Section 2.1049 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Equipment Authorization Procedures Certification § 2.1049 Measurements required:...

  10. 47 CFR 2.1049 - Measurements required: Occupied bandwidth.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false Measurements required: Occupied bandwidth. 2.1049 Section 2.1049 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Equipment Authorization Procedures Certification § 2.1049 Measurements required:...

  11. Bandwidth utilization maximization of scientific RF communication systems

    SciTech Connect

    Rey, D.; Ryan, W.; Ross, M.

    1997-01-01

    A method for more efficiently utilizing the frequency bandwidth allocated for data transmission is presented. Current space and range communication systems use modulation and coding schemes that transmit 0.5 to 1.0 bits per second per Hertz of radio frequency bandwidth. The goal in this LDRD project is to increase the bandwidth utilization by employing advanced digital communications techniques. This is done with little or no increase in the transmit power which is usually very limited on airborne systems. Teaming with New Mexico State University, an implementation of trellis coded modulation (TCM), a coding and modulation scheme pioneered by Ungerboeck, was developed for this application and simulated on a computer. TCM provides a means for reliably transmitting data while simultaneously increasing bandwidth efficiency. The penalty is increased receiver complexity. In particular, the trellis decoder requires high-speed, application-specific digital signal processing (DSP) chips. A system solution based on the QualComm Viterbi decoder and the Graychip DSP receiver chips is presented.

  12. 47 CFR 2.1049 - Measurements required: Occupied bandwidth.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Measurements required: Occupied bandwidth. 2.1049 Section 2.1049 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Equipment Authorization Procedures Certification § 2.1049 Measurements required:...

  13. Bandwidth compression of the digitized HDTV images for transmission via satellites

    NASA Astrophysics Data System (ADS)

    Al-Asmari, A. Kh.; Kwatra, S. C.

    1992-03-01

    This paper investigates a subband coding scheme to reduce the transmission bandwidth of the digitized HDTV images. The HDTV signals are decomposed into seven bands. Each band is then independently encoded. The based band is DPCM encoded and the high bands are encoded by using nonuniform Laplacian quantizers with a dead zone. By selecting the dead zone on the basis of energy in the high bands an acceptable image quality is achieved at an average of 45 Mbits/sec (Mbps) rate. This rate is comparable to some very hardware intensive schemes of transform compression or vector quantization proposed in the literature. The subband coding scheme used in this study is considered to be of medium complexity. The 45 Mbps rate is suitable for transmission of HDTV signals via satellites.

  14. Acceptance, values, and probability.

    PubMed

    Steel, Daniel

    2015-10-01

    This essay makes a case for regarding personal probabilities used in Bayesian analyses of confirmation as objects of acceptance and rejection. That in turn entails that personal probabilities are subject to the argument from inductive risk, which aims to show non-epistemic values can legitimately influence scientific decisions about which hypotheses to accept. In a Bayesian context, the argument from inductive risk suggests that value judgments can influence decisions about which probability models to accept for likelihoods and priors. As a consequence, if the argument from inductive risk is sound, then non-epistemic values can affect not only the level of evidence deemed necessary to accept a hypothesis but also degrees of confirmation themselves. PMID:26386533

  15. Newbery Medal Acceptance.

    ERIC Educational Resources Information Center

    Freedman, Russell

    1988-01-01

    Presents the Newbery Medal acceptance speech of Russell Freedman, writer of children's nonfiction. Discusses the place of nonfiction in the world of children's literature, the evolution of children's biographies, and the author's work on "Lincoln." (ARH)

  16. Newbery Medal Acceptance.

    ERIC Educational Resources Information Center

    Cleary, Beverly

    1984-01-01

    Reprints the text of Ms. Cleary's Newbery medal acceptance speech in which she gives personal history concerning her development as a writer and her response to the letters she receives from children. (CRH)

  17. Caldecott Medal Acceptance.

    ERIC Educational Resources Information Center

    Provensen, Alice; Provensen, Martin

    1984-01-01

    Reprints the text of the Provensens' Caldecott medal acceptance speech in which they describe their early interest in libraries and literature, the collaborative aspect of their work, and their current interest in aviation. (CRH)

  18. Long-term solution to the imagery bandwidth problem

    NASA Astrophysics Data System (ADS)

    Kent, Dennis C.

    1996-11-01

    There are numerous technological challenges in the Tactical Reconnaissance (Tac Recce) arena as the digital imagery era dawns. Foremost among them are the problems of imagery transmission bandwidth and the storage of the collected imagery. In this paper I seek to address these problems in an interrelated manner. I do not propose any new technological innovation, but rather a fundamental change in the philosophy of the collection, transmission, and storage of tactical imagery. The core of the approach requires that the area being imaged has already been imaged before (old imagery). This is reasonable given satellite, long range, UAV, and tactical imagery collection systems presently planned for, anticipated data collection rates, and how hot spots are repeatedly imaged. In addition, the Defense Airborne Reconnaissance Office (DARO) expects to be imaging tens of thousands of square kilometers each day within the next decade. When new tasking to collect imaging is received, imagery collected before by some imagery collection system must be taken with the aircraft (A/C) or person sent out to collect new imagery. As the new imagery is collected, the old and new imagery of the same area would be automatically registered. The old imagery can be pre-scaled, pre-warped, pre-rotated, etc., in order to maximize the efficiency of this process. The registered images can be spatially and spectrally thresholded in order to isolate significant deltas. Automatic target cueing (ATC)/automatic target recognition (ATR) could be used on both images for comparison to further isolate new objects of interest. Segmentation techniques could then be used to extract objects or regions of interest from the new image and only these objects or regions would be transmitted to the ground, a relay aircraft, or a satellite. Once at the ground station or long-term storage site, the new information could be inserted into the original image, thus minimizing the amount of storage space required as areas

  19. A Wide Bandwidth Model for the Electrical Impedance of Magnetic BearingS

    NASA Technical Reports Server (NTRS)

    Meeker, David C.; Maslen, Eric H.; Noh, Myounggyu D.

    1996-01-01

    Magnetic bearings are often designed using magnetic circuit theory. When these bearings are built, however, effects not included in the usual circuit theory formulation have a significant influence on bearing performance. Two significant sources of error in the circuit theory approach are the neglect of leakage and fringing effects and the neglect of eddy current effects. This work formulates an augmented circuit model in which eddy current and flux leakage and fringing effects are included. Through the use of this model, eddy current power losses and actuator bandwidth can be derived. Electrical impedance predictions from the model are found to be in good agreement with experimental data from a typical magnetic bearing.

  20. A 15 MHz bandwidth, 60 Vpp, low distortion power amplifier for driving high power piezoelectric transducers.

    PubMed

    Capineri, Lorenzo

    2014-10-01

    This paper presents the design and the realization of a linear power amplifier with large bandwidth (15 MHz) capable of driving low impedance ultrasonic transducers. The output current driving capability (up to 5 A) and low distortion makes it suitable for new research applications using high power ultrasound in the medical and industrial fields. The electronic design approach is modular so that the characteristics can be scaled according to specific applications and implementation details for the circuit layout are reported. Finally the characterization of the power amplifier module is presented. PMID:25362428

  1. Real-time monitoring in passive optical access networks using L-band ASE and varied bandwidth and reflectivity of fiber Bragg gratings

    NASA Astrophysics Data System (ADS)

    Naim, Nani Fadzlina; Bakar, A. Ashrif A.; Ab-Rahman, Mohammad Syuhaimi

    2016-05-01

    This paper presents a passive optical access network monitoring approach using an L-band amplified spontaneous emission source and varied bandwidths, reflectivity and Bragg wavelengths of fiber Bragg gratings (FBGs). In this technique, the reflection spectra of dedicated FBGs are used as the branch identifier to monitor the integrity of the distribution fiber in a point-to-multipoint network. FBGs with different bandwidths, reflectivity and Bragg wavelengths were used to monitor an increased number of optical network units within the limited bandwidth of the monitoring source. Simulations and experimental testing have been conducted to ensure the feasibility of this system. An experimental setup using four FBGs was conducted for different types of splitters. The signal processing to determine the faulty branches is presented. This system is capable of monitoring up to 32 distribution fibers using a limited monitoring source bandwidth of 10.8 nm with a power margin of 2 dB.

  2. Pulse Shaped 8-PSK Bandwidth Efficiency and Spectral Spike Elimination

    NASA Technical Reports Server (NTRS)

    Tao, Jian-Ping

    1998-01-01

    The most bandwidth-efficient communication methods are imperative to cope with the congested frequency bands. Pulse shaping methods have excellent effects on narrowing bandwidth and increasing band utilization. The position of the baseband filters for the pulse shaping is crucial. Post-modulation pulse shaping (a low pass filter is located after the modulator) can change signals from constant envelope to non-constant envelope, and non-constant envelope signals through non-linear device (a SSPA or TWT) can further spread the power spectra. Pre-modulation pulse shaping (a filter is located before the modulator) will have constant envelope. These two pulse shaping methods have different effects on narrowing the bandwidth and producing bit errors. This report studied the effect of various pre-modulation pulse shaping filters with respect to bandwidth, spectral spikes and bit error rate. A pre-modulation pulse shaped 8-ary Phase Shift Keying (8PSK) modulation was used throughout the simulations. In addition to traditional pulse shaping filters, such as Bessel, Butterworth and Square Root Raised Cosine (SRRC), other kinds of filters or pulse waveforms were also studied in the pre-modulation pulse shaping method. Simulations were conducted by using the Signal Processing Worksystem (SPW) software package on HP workstations which simulated the power spectral density of pulse shaped 8-PSK signals, end to end system performance and bit error rates (BERS) as a function of Eb/No using pulse shaping in an AWGN channel. These results are compared with the post-modulation pulse shaped 8-PSK results. The simulations indicate traditional pulse shaping filters used in pre-modulation pulse shaping may produce narrower bandwidth, but with worse BER than those in post-modulation pulse shaping. Theory and simulations show pre- modulation pulse shaping could also produce discrete line power spectra (spikes) at regular frequency intervals. These spikes may cause interference with adjacent

  3. Brewster-angled chirped mirrors for high-fidelity dispersion compensation and bandwidths exceeding one optical octave

    NASA Astrophysics Data System (ADS)

    Steinmeyer, G.

    2003-09-01

    A novel design approach for dispersion-compensating chirped mirrors with greater-than-octave bandwidth is proposed. The commonly encountered problem of dispersion ripple is overcome by impedance matching via Brewster incidence in respect to the top-layer coating material. This approach totally suppresses undesired reflections off the interface to the ambient medium without any need for complicated matching sections. It is shown that Brewster-angled chirped mirrors can deliver ultrabroadband dispersion compensation over a much wider bandwidth than conventional doublechirped mirrors and without the mechanical complexity of back-deposition approaches. Due to their relatively simple structure, the sensitivity of the dispersion of the Brewster-angled designs towards growth errors is greatly reduced. Therefore, this new generation of chirped mirrors appears ideal for compression of continuum pulses with a potential of pulse durations in the single-cycle regime.

  4. Wide bandwidth transimpedance amplifier for extremely high sensitivity continuous measurements

    NASA Astrophysics Data System (ADS)

    Ferrari, Giorgio; Sampietro, Marco

    2007-09-01

    This article presents a wide bandwidth transimpedance amplifier based on the series of an integrator and a differentiator stage, having an additional feedback loop to discharge the standing current from the device under test (DUT) to ensure an unlimited measuring time opportunity when compared to switched discharge configurations while maintaining a large signal amplification over the full bandwidth. The amplifier shows a flat response from 0.6Hzto1.4MHz, the capability to operate with leakage currents from the DUT as high as tens of nanoamperes, and rail-to-rail dynamic range for sinusoidal current signals independent of the DUT leakage current. Also available is a monitor output of the stationary current to track experimental slow drifts. The circuit is ideal for noise spectral and impedance measurements of nanodevices and biomolecules when in the presence of a physiological medium and in all cases where high sensitivity current measurements are requested such as in scanning probe microscopy systems.

  5. Optical interconnect technologies for high-bandwidth ICT systems

    NASA Astrophysics Data System (ADS)

    Chujo, Norio; Takai, Toshiaki; Mizushima, Akiko; Arimoto, Hideo; Matsuoka, Yasunobu; Yamashita, Hiroki; Matsushima, Naoki

    2016-03-01

    The bandwidth of information and communication technology (ICT) systems is increasing and is predicted to reach more than 10 Tb/s. However, an electrical interconnect cannot achieve such bandwidth because of its density limits. To solve this problem, we propose two types of high-density optical fiber wiring for backplanes and circuit boards such as interface boards and switch boards. One type uses routed ribbon fiber in a circuit board because it has the ability to be formed into complex shapes to avoid interfering with the LSI and electrical components on the board. The backplane is required to exhibit high density and flexibility, so the second type uses loose fiber. We developed a 9.6-Tb/s optical interconnect demonstration system using embedded optical modules, optical backplane, and optical connector in a network apparatus chassis. We achieved 25-Gb/s transmission between FPGAs via the optical backplane.

  6. Bandwidth efficient block codes for M-ary PSK modulation

    NASA Technical Reports Server (NTRS)

    Lin, Shu

    1987-01-01

    A class of bandwidth efficient block codes for M-ary PSK modulation is presented. A soft-decision decoding for this class of codes is devised. Some specific short codes for Quad Phase Shift Key (QPSK), 8-PSK and 16-PSK modulations are constructed. These codes have good minimum squared Euclidean distances and provide 2 to 5.8 dB coding gains over uncoded QPSK modulation without (or with little) bandwidth expansion. The complete weight distributions of these specific codes are determined. Based on these weight distributions, their error probabilities are evaluated. Some of these codes have simple trellis structures and hence can be decoded by Viterbi decoding algorithm with relatively simple implementation. Moreover, the codes are very suitable for use as inner codes for various cascaded coding schemes with Reed-Solomon codes as outer codes.

  7. Optimal modified tracking performance for MIMO systems under bandwidth constraint.

    PubMed

    Sun, Xin-Xiang; Wu, Jie; Zhan, Xi-Sheng; Han, Tao

    2016-05-01

    This paper investigates the optimal modified tracking performance of multi-input multi-output (MIMO) networked control systems (NCSs) with bandwidth and channel noise constraints. A new modified tracking performance index is proposed which prevents variations in the tracking error from leading to invalid data where there is no integrator in the plant. An expression for the optimal modified tracking performance is obtained using a method which includes co-prime factorization, partial factorization, spectral decomposition and H2 norm. The obtained results show that the optimal modified tracking performance is influenced by the non-minimum phase (NMP) zeros, unstable poles, and their directions. Furthermore, the characteristics of the input signal, the modification factor, the bandwidth and the channel noise are also shown to be closely related to the optimal modified tracking performance. Finally, the efficiency of the result is verified using some typical examples. PMID:26874745

  8. Long-pulse-width narrow-bandwidth solid state laser

    DOEpatents

    Dane, C. Brent; Hackel, Lloyd A.

    1997-01-01

    A long pulse laser system emits 500-1000 ns quasi-rectangular pulses at 527 nm with near diffraction-limited divergence and near transform-limited bandwidth. The system consists of one or more flashlamp-pumped Nd:glass zig-zag amplifiers, a very low threshold stimulated-Brillouin-scattering (SBS) phase conjugator system, and a free-running single frequency Nd:YLF master oscillator. Completely passive polarization switching provides eight amplifier gain passes. Multiple frequency output can be generated by using SBS cells having different pressures of a gaseous SBS medium or different SBS materials. This long pulse, low divergence, narrow-bandwidth, multi-frequency output laser system is ideally suited for use as an illuminator for long range speckle imaging applications. Because of its high average power and high beam quality, this system has application in any process which would benefit from a long pulse format, including material processing and medical applications.

  9. Long-pulse-width narrow-bandwidth solid state laser

    DOEpatents

    Dane, C.B.; Hackel, L.A.

    1997-11-18

    A long pulse laser system emits 500-1000 ns quasi-rectangular pulses at 527 nm with near diffraction-limited divergence and near transform-limited bandwidth. The system consists of one or more flashlamp-pumped Nd:glass zig-zag amplifiers, a very low threshold stimulated-Brillouin-scattering (SBS) phase conjugator system, and a free-running single frequency Nd:YLF master oscillator. Completely passive polarization switching provides eight amplifier gain passes. Multiple frequency output can be generated by using SBS cells having different pressures of a gaseous SBS medium or different SBS materials. This long pulse, low divergence, narrow-bandwidth, multi-frequency output laser system is ideally suited for use as an illuminator for long range speckle imaging applications. Because of its high average power and high beam quality, this system has application in any process which would benefit from a long pulse format, including material processing and medical applications. 5 figs.

  10. Exploiting material softening in hard PZTs for resonant bandwidth enhancement

    NASA Astrophysics Data System (ADS)

    Leadenham, S.; Moura, A.; Erturk, A.

    2016-04-01

    Intentionally designed nonlinearities have been employed by several research groups to enhance the frequency bandwidth of vibration energy harvesters. Another type of nonlinear resonance behavior emerges from the piezoelectric constitutive behavior for high excitation levels and is manifested in the form of softening stiffness. This material nonlinearity does not result in the jump phenomenon in soft piezoelectric ceramics, e.g. PZT-5A and PZT-5H, due to their large internal dissipation. This paper explores the potential for wideband energy harvesting using a hard (relatively high quality factor) PZT-8 bimorph by exploiting its material softening. A wide range of base excitation experiments conducted for a set of resistive electrical loads confirms the frequency bandwidth enhancement.

  11. The Optical Lightpipe as a High-Bandwidth Fusion Diagnostic

    SciTech Connect

    Moran, M J; Lerche, R A; Mant, G; Glebov, V Y; Sangster, T C; Mack, J M

    2006-07-21

    A recent series of experiments at the University of Rochester Laboratory for Laser Energetics OMEGA facility studied the feasibility of using radiation-to-light converters and high bandwidth optical signal transmission to remote recording devices as an alternate nuclear diagnostic method. A prototype system included a radiation-to-light converter, a multiple-section light pipe consisting of stainless steel tubes with polished interiors and turning mirrors, and a streak camera or photomultiplier/digitizer combination for signal recording. Several different radiation-to-light converters (scintillators, glasses, plastics, and pressurized CO{sub 2}) performed well and produced predictable optical emissions. The lightpipe transmitted high-bandwidth optical signals to the recording stations. Data were recorded with the streak camera, the photomultiplier/digitizer, and with both recorders simultaneously.

  12. Anamorphic transformation and its application to time-bandwidth compression.

    PubMed

    Asghari, Mohammad H; Jalali, Bahram

    2013-09-20

    A general method for compressing the modulation time-bandwidth product of analog signals is introduced. As one of its applications, this physics-based signal grooming, performed in the analog domain, allows a conventional digitizer to sample and digitize the analog signal with variable resolution. The net result is that frequency components that were beyond the digitizer bandwidth can now be captured and, at the same time, the total digital data size is reduced. This compression is lossless and is achieved through a feature selective reshaping of the signal's complex field, performed in the analog domain prior to sampling. Our method is inspired by operation of Fovea centralis in the human eye and by anamorphic transformation in visual arts. The proposed transform can also be performed in the digital domain as a data compression algorithm to alleviate the storage and transmission bottlenecks associated with "big data." PMID:24085172

  13. H-infinity control with bandwidth and H2 constraints

    NASA Technical Reports Server (NTRS)

    Belcastro, Christine M.; Chang, B.-C.; Zong, R.; Fischl, Robert

    1991-01-01

    A discussion is presented of practical issues associated with H-infinity controller design based on the results presented by Doyle et al. (1989). First, the optimal H-infinity controller based on these results is discussed from a practical application point of view. Then, tradeoffs between the H-infinity norm and other performance characteristics, specifically bandwidth and the H2 norm, are considered. It is shown that when the optimal H-infinity norm is relaxed by only 10-20 percent and the central controller from Doyle et al. is used, significant benefits in both the controller bandwidth and the H2 norm of the closed-loop system can be achieved.

  14. Bandwidth Study of the Microwave Reflectors with Rectangular Corrugations

    NASA Astrophysics Data System (ADS)

    Zhang, Liang; He, Wenlong; Donaldson, Craig R.; Cross, Adrian W.

    2016-09-01

    The mode-selective microwave reflector with periodic rectangular corrugations in the inner surface of a circular metallic waveguide is studied in this paper. The relations between the bandwidth and reflection coefficient for different numbers of corrugation sections were studied through a global optimization method. Two types of reflectors were investigated. One does not consider the phase response and the other does. Both types of broadband reflectors operating at W-band were machined and measured to verify the numerical simulations.

  15. Amplifier similariton laser with extra-broad bandwidth output pulse

    NASA Astrophysics Data System (ADS)

    Korobko, D. A.; Okhotnikov, O. G.; Zolotovskii, I. O.

    2016-03-01

    We propose an advanced scheme of amplifier similariton laser providing an output pulse spectrum much wider than the gain bandwidth. The upgrade is an additional dispersive element introduced into the cavity to locally increase the peak pulse power. The proposed scheme demonstrates a drastic increase in the output pulse spectrum width, reduction of the pulse duration, and an increase in the output peak pulse power after compression.

  16. Frequency doubling of fiber laser radiation of large spectral bandwidths

    NASA Astrophysics Data System (ADS)

    Nyga, Sebastian; Geiger, Jens; Jungbluth, Bernd

    2010-02-01

    In this work the reduction of conversion efficiency due to spectral bandwidth of fiber laser radiation is investigated. Subsequently, compensation optics to correct the spectral phase mismatching inside the nonlinear crystal is dimensioned and tested. For the experimental study a laboratory fiber laser setup is used consisting of a seed diode and a three stage fiber amplifier. The laser delivers an average output power of up to 100 W at 1 MHz. Even below the Raman threshold the output is far away from Fourier limit, providing a nearly Lorentzian spectral shape and a temporal pulse width of 800 ps. As the bandwidth increases nearly linearly with the pump power of the third amplifier stage, this parameter could be controlled for the experiments. All conversion experiments are conducted with a moderate load of the nonlinear crystals, i.e. intensity less than 150 MW/cm2. Without compensation of the spectral phase mismatch, a maximum conversion efficiency of 15 % is attained for a Type I configuration with a 20mm long LBO crystal. Using the compensation setup 27 W of green light are obtained from 60 W infrared light at a bandwidth of 4.7 nm. Therefore the efficiency rises to 44% at the same load.

  17. Analysis of the vibrational bandwidths of alkane-urea clathrates

    NASA Astrophysics Data System (ADS)

    Wood, Kurt A.; Snyder, Robert G.; Strauss, Herbert L.

    1989-11-01

    The only large amplitude motion possible for an n-alkane molecule in urea-inclusion compounds is libration-torsion about the long axis of the chain. We present a quantitative model that incorporates the effect of this motion on the widths of the alkane vibrational bands. This model explains the difference in the widths of the different vibrations of the alkanes and their temperature dependence. Two effects are combined: (1) a modulation of the angles between the components of the polarizability in the space and the molecule-fixed frames for Raman spectra or between the components of the dipole moment for the infrared spectra, and (2) a modulation of the frequency of the alkane vibration via anharmonic coupling terms with the libration-torsion. The first effect gives rise to a distinctly non-Lorentzian band shape, which is convoluted with the approximately Lorentzian band of the second effect to produce the final result. The libration-torsional motion is modeled as that of a Brownian harmonic oscillator. Most of the parameters that enter the calculation are obtained from data other than that involving the bandwidths themselves. The libration-torsion relaxation time of about 1 ps obtained from fitting the observed bandwidths agrees with the value obtained from recent quasielastic neutron scattering experiments. Other bandwidth mechanisms that have been proposed are evaluated and it is shown that site hopping is too slow to account for the observations.

  18. Managing high-bandwidth real-time data storage

    SciTech Connect

    Bigelow, David D.; Brandt, Scott A; Bent, John M; Chen, Hsing-Bung

    2009-09-23

    There exist certain systems which generate real-time data at high bandwidth, but do not necessarily require the long-term retention of that data in normal conditions. In some cases, the data may not actually be useful, and in others, there may be too much data to permanently retain in long-term storage whether it is useful or not. However, certain portions of the data may be identified as being vitally important from time to time, and must therefore be retained for further analysis or permanent storage without interrupting the ongoing collection of new data. We have developed a system, Mahanaxar, intended to address this problem. It provides quality of service guarantees for incoming real-time data streams and simultaneous access to already-recorded data on a best-effort basis utilizing any spare bandwidth. It has built in mechanisms for reliability and indexing, can scale upwards to meet increasing bandwidth requirements, and handles both small and large data elements equally well. We will show that a prototype version of this system provides better performance than a flat file (traditional filesystem) based version, particularly with regard to quality of service guarantees and hard real-time requirements.

  19. Neural bandwidth of veridical perception across the visual field.

    PubMed

    Wilkinson, Michael O; Anderson, Roger S; Bradley, Arthur; Thibos, Larry N

    2016-01-01

    Neural undersampling of the retinal image limits the range of spatial frequencies that can be represented veridically by the array of retinal ganglion cells conveying visual information from eye to brain. Our goal was to demarcate the neural bandwidth and local anisotropy of veridical perception, unencumbered by optical imperfections of the eye, and to test competing hypotheses that might account for the results. Using monochromatic interference fringes to stimulate the retina with high-contrast sinusoidal gratings, we measured sampling-limited visual resolution along eight meridians from 0° to 50° of eccentricity. The resulting isoacuity contour maps revealed all of the expected features of the human array of retinal ganglion cells. Contours in the radial fringe maps are elongated horizontally, revealing the functional equivalent of the anatomical visual streak, and are extended into nasal retina and superior retina, indicating higher resolution along those meridians. Contours are larger in diameter for radial gratings compared to tangential or oblique gratings, indicating local anisotropy with highest bandwidth for radially oriented gratings. Comparison of these results to anatomical predictions indicates acuity is proportional to the sampling density of retinal ganglion cells everywhere in the retina. These results support the long-standing hypothesis that "pixel density" of the discrete neural image carried by the human optic nerve limits the spatial bandwidth of veridical perception at all retinal locations. PMID:26824638

  20. High-bandwidth remote flat panel display interconnect system

    NASA Astrophysics Data System (ADS)

    Peterson, Darrel G.

    1999-08-01

    High performance electronic displays (CRT, AMLCD, TFEL, plasma, etc.) require wide bandwidth electrical drive signals to produce the desired display images. When the image generation and/or image processing circuitry is located within the same line replaceable unit (LRU) as the display media, the transmission of the display drive signals to the display media presents no unusual design problems. However, many aircraft cockpits are severely constrained for available space behind the instrument panel. This often forces the system designer to specify that only the display media and its immediate support circuitry are to be mounted in the instrument panel. A wide bandwidth interconnect system is then required to transfer image data from the display generation circuitry to the display unit. Image data transfer rates of nearly 1.5 Gbits/second may be required when displaying full motion video at a 60 Hz field rate. In addition to wide bandwidth, this interconnect system must exhibit several additional key characteristics: (1) Lossless transmission of image data; (2) High reliability and high integrity; (3) Ease of installation and field maintenance; (4) High immunity to HIRF and electrical noise; (5) Low EMI emissions; (6) Long term supportability; and (7) Low acquisition and maintenance cost. Rockwell Collins has developed an avionics grade remote display interconnect system based on the American National Standards Institute Fibre Channel standard which meets these requirements. Readily available low cost commercial off the shelf (COTS) components are utilized, and qualification tests have confirmed system performance.

  1. Effect of Ni-Zn ferrite on bandwidth and radiation efficiency of embedded antenna for mobile phone

    NASA Astrophysics Data System (ADS)

    Bae, S.; Hong, Y. K.; Lyle, A.

    2008-04-01

    Performance of inverted F meander antenna with a lossy ferrite film was investigated and compared to air-core antenna with the same design. We have fabricated ferrite film antenna using 3μm thick plated Ni0.21Zn0.45Fe2.34O4. Loss tanδμ of the plated ferrite was about 1.5 around 500MHz. It was found that bandwidth significantly increased by the use of lossy ferrite, while radiation efficiency (RE) decreased. However, the RE increases as the thickness of lossy ferrite film decreases below 10μm. The fractional bandwidth of ferrite film antenna was found to be 13.8%, which shows a 431% as compared to an air-core antenna. The center frequency (fc) for ferrite film antenna decreased from 584to534MHz of the air-core antenna. This implies 7.5% decrease in the fc, while the gain of the ferrite was not much lower than the air-core antenna. Lossy ferrite thin film has been found to be effective in broadening of bandwidth, while retaining an acceptable gain.

  2. Accept or divert?

    PubMed

    Angelucci, P A

    1999-09-01

    Stretching scarce resources is more than a managerial issue. Should you accept the patient to an understaffed ICU or divert him to another facility? The intense "medical utility" controversy focuses on a situation that critical care nurses now face every day. PMID:10614370

  3. 1984 Newbery Acceptance Speech.

    ERIC Educational Resources Information Center

    Cleary, Beverly

    1984-01-01

    This acceptance speech for an award honoring "Dear Mr. Henshaw," a book about feelings of a lonely child of divorce intended for eight-, nine-, and ten-year-olds, highlights children's letters to author. Changes in society that affect children, the inception of "Dear Mr. Henshaw," and children's reactions to books are highlighted. (EJS)

  4. Why was Relativity Accepted?

    NASA Astrophysics Data System (ADS)

    Brush, S. G.

    Historians of science have published many studies of the reception of Einstein's special and general theories of relativity. Based on a review of these studies, and my own research on the role of the light-bending prediction in the reception of general relativity, I discuss the role of three kinds of reasons for accepting relativity (1) empirical predictions and explanations; (2) social-psychological factors; and (3) aesthetic-mathematical factors. According to the historical studies, acceptance was a three-stage process. First, a few leading scientists adopted the special theory for aesthetic-mathematical reasons. In the second stage, their enthusiastic advocacy persuaded other scientists to work on the theory and apply it to problems currently of interest in atomic physics. The special theory was accepted by many German physicists by 1910 and had begun to attract some interest in other countries. In the third stage, the confirmation of Einstein's light-bending prediction attracted much public attention and forced all physicists to take the general theory of relativity seriously. In addition to light-bending, the explanation of the advance of Mercury's perihelion was considered strong evidence by theoretical physicists. The American astronomers who conducted successful tests of general relativity became defenders of the theory. There is little evidence that relativity was `socially constructed' but its initial acceptance was facilitated by the prestige and resources of its advocates.

  5. UGV acceptance testing

    NASA Astrophysics Data System (ADS)

    Kramer, Jeffrey A.; Murphy, Robin R.

    2006-05-01

    With over 100 models of unmanned vehicles now available for military and civilian safety, security or rescue applications, it is important to for agencies to establish acceptance testing. However, there appears to be no general guidelines for what constitutes a reasonable acceptance test. This paper describes i) a preliminary method for acceptance testing by a customer of the mechanical and electrical components of an unmanned ground vehicle system, ii) how it has been applied to a man-packable micro-robot, and iii) discusses the value of testing both to ensure that the customer has a workable system and to improve design. The test method automated the operation of the robot to repeatedly exercise all aspects and combinations of components on the robot for 6 hours. The acceptance testing process uncovered many failures consistent with those shown to occur in the field, showing that testing by the user does predict failures. The process also demonstrated that the testing by the manufacturer can provide important design data that can be used to identify, diagnose, and prevent long-term problems. Also, the structured testing environment showed that sensor systems can be used to predict errors and changes in performance, as well as uncovering unmodeled behavior in subsystems.

  6. Optical fiber characterization: Backscatter, time domain bandwidth, refracted from near field and interlaboratory comparisons, volume 1

    NASA Astrophysics Data System (ADS)

    Danielson, B. L.; Day, G. W.; Franzen, D. L.; Kim, E. M.; Young, M.

    1982-09-01

    Optical fiber waveguide measurements are described. Systems to determine the backscatter, bandwidth, and index profile are covered in detail. Measurement comparisons between laboratories are given for fiber attenuation, bandwidth, numerical aperture, and core diameter.

  7. Final Report on DOE Project entitled Dynamic Optimized Advanced Scheduling of Bandwidth Demands for Large-Scale Science Applications

    SciTech Connect

    Ramamurthy, Byravamurthy

    2014-05-05

    In this project, developed scheduling frameworks for dynamic bandwidth demands for large-scale science applications. In particular, we developed scheduling algorithms for dynamic bandwidth demands in this project. Apart from theoretical approaches such as Integer Linear Programming, Tabu Search and Genetic Algorithm heuristics, we have utilized practical data from ESnet OSCARS project (from our DOE lab partners) to conduct realistic simulations of our approaches. We have disseminated our work through conference paper presentations and journal papers and a book chapter. In this project we addressed the problem of scheduling of lightpaths over optical wavelength division multiplexed (WDM) networks. We published several conference papers and journal papers on this topic. We also addressed the problems of joint allocation of computing, storage and networking resources in Grid/Cloud networks and proposed energy-efficient mechanisms for operatin optical WDM networks.

  8. Significantly Improving Regional Seismic Amplitude Tomography at Higher Frequencies by Determining S -Wave Bandwidth

    DOE PAGESBeta

    Fisk, Mark D.; Pasyanos, Michael E.

    2016-05-03

    Characterizing regional seismic signals continues to be a difficult problem due to their variability. Calibration of these signals is very important to many aspects of monitoring underground nuclear explosions, including detecting seismic signals, discriminating explosions from earthquakes, and reliably estimating magnitude and yield. Amplitude tomography, which simultaneously inverts for source, propagation, and site effects, is a leading method of calibrating these signals. A major issue in amplitude tomography is the data quality of the input amplitude measurements. Pre-event and prephase signal-to-noise ratio (SNR) tests are typically used but can frequently include bad signals and exclude good signals. The deficiencies ofmore » SNR criteria, which are demonstrated here, lead to large calibration errors. To ameliorate these issues, we introduce a semi-automated approach to assess the bandwidth of a spectrum where it behaves physically. We determine the maximum frequency (denoted as Fmax) where it deviates from this behavior due to inflections at which noise or spurious signals start to bias the spectra away from the expected decay. We compare two amplitude tomography runs using the SNR and new Fmax criteria and show significant improvements to the stability and accuracy of the tomography output for frequency bands higher than 2 Hz by using our assessments of valid S-wave bandwidth. We compare Q estimates, P/S residuals, and some detailed results to explain the improvements. Lastly, for frequency bands higher than 4 Hz, needed for effective P/S discrimination of explosions from earthquakes, the new bandwidth criteria sufficiently fix the instabilities and errors so that the residuals and calibration terms are useful for application.« less

  9. Loudness of subcritical sounds as a function of bandwidth, center frequency, and level.

    PubMed

    Hots, J; Rennies, J; Verhey, J L

    2014-03-01

    Level differences at equal loudness between band-pass noise and pure tones with a frequency equal to the center frequency of the noise were measured in normal-hearing listeners using a loudness matching procedure. The center frequencies were 750, 1500, and 3000 Hz and noise bandwidths from 5 to 1620 Hz were used. The level of the reference pure tone was 30, 50, or 70 dB. For all center frequencies and reference levels, the level at equal loudness was close to 0 dB for the narrowest bandwidth, increased with bandwidth for bandwidths smaller than the critical bandwidth, and decreased for bandwidths larger than the critical bandwidth. For bandwidths considerably larger than the critical bandwidth, the level difference was negative. The maximum positive level difference was measured for a bandwidth close to the critical bandwidth. This maximum level difference decreased with increasing reference level. A similar effect was found when the level differences were derived from data of an additional categorical loudness scaling experiment. The results indicate that the decrease of loudness at equal level with increasing subcritical bandwidth is a common property of the auditory system which is not taken into account in current loudness models. PMID:24606270

  10. Two-photon fluorescence excitation spectroscopy by pulse shaping ultrabroad-bandwidth femtosecond laser pulses

    SciTech Connect

    Xu Bingwei; Coello, Yves; Lozovoy, Vadim V.; Dantus, Marcos

    2010-11-10

    A fast and automated approach to measuring two-photon fluorescence excitation (TPE) spectra of fluorophores with high resolution ({approx}2 nm ) by pulse shaping ultrabroad-bandwidth femtosecond laser pulses is demonstrated. Selective excitation in the range of 675-990 nm was achieved by imposing a series of specially designed phase and amplitude masks on the excitation pulses using a pulse shaper. The method eliminates the need for laser tuning and is, thus, suitable for non-laser-expert use. The TPE spectrum of Fluorescein was compared with independent measurements and the spectra of the pH-sensitive dye 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS) in acidic and basic environments were measured for the first time using this approach.

  11. Acceptability of human risk.

    PubMed Central

    Kasperson, R E

    1983-01-01

    This paper has three objectives: to explore the nature of the problem implicit in the term "risk acceptability," to examine the possible contributions of scientific information to risk standard-setting, and to argue that societal response is best guided by considerations of process rather than formal methods of analysis. Most technological risks are not accepted but are imposed. There is also little reason to expect consensus among individuals on their tolerance of risk. Moreover, debates about risk levels are often at base debates over the adequacy of the institutions which manage the risks. Scientific information can contribute three broad types of analyses to risk-setting deliberations: contextual analysis, equity assessment, and public preference analysis. More effective risk-setting decisions will involve attention to the process used, particularly in regard to the requirements of procedural justice and democratic responsibility. PMID:6418541

  12. A bandwidth efficient coding scheme for the Hubble Space Telescope

    NASA Astrophysics Data System (ADS)

    Pietrobon, Steven S.; Costello, Daniel J., Jr.

    1991-11-01

    As a demonstration of the performance capabilities of trellis codes using multidimensional signal sets, a Viterbi decoder was designed. The choice of code was based on two factors. The first factor was its application as a possible replacement for the coding scheme currently used on the Hubble Space Telescope (HST). The HST at present uses the rate 1/3 nu = 6 (with 2 (exp nu) = 64 states) convolutional code with Binary Phase Shift Keying (BPSK) modulation. With the modulator restricted to a 3 Msym/s, this implies a data rate of only 1 Mbit/s, since the bandwidth efficiency K = 1/3 bit/sym. This is a very bandwidth inefficient scheme, although the system has the advantage of simplicity and large coding gain. The basic requirement from NASA was for a scheme that has as large a K as possible. Since a satellite channel was being used, 8PSK modulation was selected. This allows a K of between 2 and 3 bit/sym. The next influencing factor was INTELSAT's intention of transmitting the SONET 155.52 Mbit/s standard data rate over the 72 MHz transponders on its satellites. This requires a bandwidth efficiency of around 2.5 bit/sym. A Reed-Solomon block code is used as an outer code to give very low bit error rates (BER). A 16 state rate 5/6, 2.5 bit/sym, 4D-8PSK trellis code was selected. This code has reasonable complexity and has a coding gain of 4.8 dB compared to uncoded 8PSK (2). This trellis code also has the advantage that it is 45 deg rotationally invariant. This means that the decoder needs only to synchronize to one of the two naturally mapped 8PSK signals in the signal set.

  13. A bandwidth efficient coding scheme for the Hubble Space Telescope

    NASA Technical Reports Server (NTRS)

    Pietrobon, Steven S.; Costello, Daniel J., Jr.

    1991-01-01

    As a demonstration of the performance capabilities of trellis codes using multidimensional signal sets, a Viterbi decoder was designed. The choice of code was based on two factors. The first factor was its application as a possible replacement for the coding scheme currently used on the Hubble Space Telescope (HST). The HST at present uses the rate 1/3 nu = 6 (with 2 (exp nu) = 64 states) convolutional code with Binary Phase Shift Keying (BPSK) modulation. With the modulator restricted to a 3 Msym/s, this implies a data rate of only 1 Mbit/s, since the bandwidth efficiency K = 1/3 bit/sym. This is a very bandwidth inefficient scheme, although the system has the advantage of simplicity and large coding gain. The basic requirement from NASA was for a scheme that has as large a K as possible. Since a satellite channel was being used, 8PSK modulation was selected. This allows a K of between 2 and 3 bit/sym. The next influencing factor was INTELSAT's intention of transmitting the SONET 155.52 Mbit/s standard data rate over the 72 MHz transponders on its satellites. This requires a bandwidth efficiency of around 2.5 bit/sym. A Reed-Solomon block code is used as an outer code to give very low bit error rates (BER). A 16 state rate 5/6, 2.5 bit/sym, 4D-8PSK trellis code was selected. This code has reasonable complexity and has a coding gain of 4.8 dB compared to uncoded 8PSK (2). This trellis code also has the advantage that it is 45 deg rotationally invariant. This means that the decoder needs only to synchronize to one of the two naturally mapped 8PSK signals in the signal set.

  14. Modulator-Based, High Bandwidth Optical Links for HEP Experiments

    NASA Astrophysics Data System (ADS)

    Underwood, David G.; Drake, G.; Fernando, W. S.; Stanek, R. W.

    2013-10-01

    As a concern with the reliability, bandwidth and mass of future optical links in LHC experiments, we are investigating CW lasers and light modulators as an alternative to VCSELs. These links will be particularly useful if they utilize light modulators which are very small, low power, high bandwidth, and are very radiation hard. We have constructed a test system with 3 such links, each operating at 10 Gb/s. We present the quality of these links (jitter, rise and fall time, BER) and eye mask margins (10GbE) for 3 different types of modulators: LiNbO3-based, InP-based, and Si-based. We present the results of radiation hardness measurements with up to ~1012 protons/cm2 and ~65 krad total ionizing dose (TID), confirming no single event effects (SEE) at 10 Gb/s with either of the 3 types of modulators. These optical links will be an integral part of intelligent tracking systems at various scales from coupled sensors through intra-module and off detector communication. We have used a Si-based photonic transceiver to build a complete 40 Gb/s bi-directional link (10 Gb/s in each of four fibers) for a 100m run and have characterized it to compare with standard VCSEL-based optical links. Some future developments of optical modulator-based high bandwidth optical readout systems, and applications based on both fiber and free space data links, such as local triggering and data readout and trigger-clock distribution, are also discussed.

  15. Systems for measuring response statistics of gigahertz bandwidth photomultipliers

    NASA Technical Reports Server (NTRS)

    Abshire, J. B.; Rowe, H. E.

    1977-01-01

    New systems have been developed for measuring the average impulse response, the pulse-height spectrum, the transit-time statistics as a function of signal level, and the dark-count spectrum of gigahertz bandwidth photomultipliers. Measurements showed that the 0.53 microns pulse used as an optical test source had a 30 picoseconds and less than 70 ps pulse width. Calibration data showed the system resolution to be less than 20 ps for root mean square transit-time measurements. Test data for a static crossed-field photomultiplier showed 2-photoelectron resolution and less than 30-ps time jitter over the 1- to 100-photoelectron range.

  16. Low Bandwidth Vocoding using EM Sensor and Acoustic Signal Processing

    SciTech Connect

    Ng, L C; Holzrichter, J F; Larson, P E

    2001-10-25

    Low-power EM radar-like sensors have made it possible to measure properties of the human speech production system in real-time, without acoustic interference [1]. By combining these data with the corresponding acoustic signal, we've demonstrated an almost 10-fold bandwidth reduction in speech compression, compared to a standard 2.4 kbps LPC10 protocol used in the STU-III (Secure Terminal Unit, third generation) telephone. This paper describes a potential EM sensor/acoustic based vocoder implementation.

  17. Bandwidth evaluation of dispersive transformation electromagnetics based devices

    NASA Astrophysics Data System (ADS)

    Argyropoulos, C.; Kallos, E.; Hao, Y.

    2011-06-01

    In this paper, the transient responses of some devices which are based on transformation electromagnetics are studied, such as invisible cloaks and concentrators, by using the Finite-Difference Time-Domain (FDTD) numerical technique. In particular, effects of the inherent losses as well as the coating size of the ideal cylindrical cloak on its bandwidth and cloaking performance are examined. In addition, it is demonstrated that the performance of transformation electromagnetics based devices is affected by the material parameters in the design, although they may behave nicely under monochromatic plane wave illuminations. The obtained results are of interest for the future practical implementation of these structures.

  18. Knowledge-based image bandwidth compression and enhancement

    NASA Astrophysics Data System (ADS)

    Saghri, John A.; Tescher, Andrew G.

    1987-01-01

    Techniques for incorporating a priori knowledge in the digital coding and bandwidth compression of image data are described and demonstrated. An algorithm for identifying and highlighting thin lines and point objects prior to coding is presented, and the precoding enhancement of a slightly smoothed version of the image is shown to be more effective than enhancement of the original image. Also considered are readjustment of the local distortion parameter and variable-block-size coding. The line-segment criteria employed in the classification are listed in a table, and sample images demonstrating the effectiveness of the enhancement techniques are presented.

  19. Optimizing bandwidth utilization in packet based telemetry systems

    SciTech Connect

    Kalibjian, J.R.

    1995-10-17

    A consistent theme in spacecraft telemetry system design is the desire to obtain maximum bandwidth utilization given a fixed transmission capability (usually due to cost/weight criteria). Extensions to basic packetization telemetry architectures are discussed which can facilitate a reduction in the amount of actual data telemetered, without loss of data quality. Central to the extensions are the establishment of an ``intelligent`` telemetry process, which can evaluate pending data to be telemetered, and act to compress, discard, or re-formulate data before actual transmission to ground stations.

  20. Flexible All-Digital Receiver for Bandwidth Efficient Modulations

    NASA Technical Reports Server (NTRS)

    Gray, Andrew; Srinivasan, Meera; Simon, Marvin; Yan, Tsun-Yee

    2000-01-01

    An all-digital high data rate parallel receiver architecture developed jointly by Goddard Space Flight Center and the Jet Propulsion Laboratory is presented. This receiver utilizes only a small number of high speed components along with a majority of lower speed components operating in a parallel frequency domain structure implementable in CMOS, and can currently process up to 600 Mbps with standard QPSK modulation. Performance results for this receiver for bandwidth efficient QPSK modulation schemes such as square-root raised cosine pulse shaped QPSK and Feher's patented QPSK are presented, demonstrating the flexibility of the receiver architecture.

  1. An Adaptive Memory Interface Controller for Improving Bandwidth Utilization of Hybrid and Reconfigurable Systems

    SciTech Connect

    Castellana, Vito G.; Tumeo, Antonino; Ferrandi, Fabrizio

    2014-05-30

    Emerging applications such as data mining, bioinformatics, knowledge discovery, social network analysis are irregular. They use data structures based on pointers or linked lists, such as graphs, unbalanced trees or unstructures grids, which generates unpredictable memory accesses. These data structures usually are large, but difficult to partition. These applications mostly are memory bandwidth bounded and have high synchronization intensity. However, they also have large amounts of inherent dynamic parallelism, because they potentially perform a task for each one of the element they are exploring. Several efforts are looking at accelerating these applications on hybrid architectures, which integrate general purpose processors with reconfigurable devices. Some solutions, which demonstrated significant speedups, include custom-hand tuned accelerators or even full processor architectures on the reconfigurable logic. In this paper we present an approach for the automatic synthesis of accelerators from C, targeted at irregular applications. In contrast to typical High Level Synthesis paradigms, which construct a centralized Finite State Machine, our approach generates dynamically scheduled hardware components. While parallelism exploitation in typical HLS-generated accelerators is usually bound within a single execution flow, our solution allows concurrently running multiple execution flow, thus also exploiting the coarser grain task parallelism of irregular applications. Our approach supports multiple, multi-ported and distributed memories, and atomic memory operations. Its main objective is parallelizing as many memory operations as possible, independently from their execution time, to maximize the memory bandwidth utilization. This significantly differs from current HLS flows, which usually consider a single memory port and require precise scheduling of memory operations. A key innovation of our approach is the generation of a memory interface controller, which

  2. Age and Acceptance of Euthanasia.

    ERIC Educational Resources Information Center

    Ward, Russell A.

    1980-01-01

    Study explores relationship between age (and sex and race) and acceptance of euthanasia. Women and non-Whites were less accepting because of religiosity. Among older people less acceptance was attributable to their lesser education and greater religiosity. Results suggest that quality of life in old age affects acceptability of euthanasia. (Author)

  3. Large-aperture wide-bandwidth antireflection-coated silicon lenses for millimeter wavelengths.

    PubMed

    Datta, R; Munson, C D; Niemack, M D; McMahon, J J; Britton, J; Wollack, E J; Beall, J; Devlin, M J; Fowler, J; Gallardo, P; Hubmayr, J; Irwin, K; Newburgh, L; Nibarger, J P; Page, L; Quijada, M A; Schmitt, B L; Staggs, S T; Thornton, R; Zhang, L

    2013-12-20

    The increasing scale of cryogenic detector arrays for submillimeter and millimeter wavelength astrophysics has led to the need for large aperture, high index of refraction, low loss, cryogenic refracting optics. Silicon with n=3.4, low loss, and high thermal conductivity is a nearly optimal material for these purposes but requires an antireflection (AR) coating with broad bandwidth, low loss, low reflectance, and a matched coefficient of thermal expansion. We present an AR coating for curved silicon optics comprised of subwavelength features cut into the lens surface with a custom three-axis silicon dicing saw. These features constitute a metamaterial that behaves as a simple dielectric coating. We have fabricated silicon lenses as large as 33.4 cm in diameter with micromachined layers optimized for use between 125 and 165 GHz. Our design reduces average reflections to a few tenths of a percent for angles of incidence up to 30° with low cross polarization. We describe the design, tolerance, manufacture, and measurements of these coatings and present measurements of the optical properties of silicon at millimeter wavelengths at cryogenic and room temperatures. This coating and lens fabrication approach is applicable from centimeter to submillimeter wavelengths and can be used to fabricate coatings with greater than octave bandwidth. PMID:24513939

  4. Large-Aperture Wide-Bandwidth Anti-Reflection-Coated Silicon Lenses for Millimeter Wavelengths

    NASA Technical Reports Server (NTRS)

    Datta, R.; Munson, C. D.; Niemack, M. D.; McMahon, J. J.; Britton, J.; Wollack, E. J.; Beall, J.; Devlin, M. J.; Fowler, J.; Gallardo, P.; Hubmayr, J.; Irwin, K.; Newburgh, L.; Nibarger, J. P.; Page, L.; Quijada, M. A.; Schmitt, B. L.; Staggs, S. T.; Thornton, R.; Zhang, L.

    2013-01-01

    The increasing scale of cryogenic detector arrays for sub-millimeter and millimeter wavelength astrophysics has led to the need for large aperture, high index of refraction, low loss, cryogenic refracting optics. Silicon with n = 3.4, low loss, and relatively high thermal conductivity is a nearly optimal material for these purposes, but requires an antireflection (AR) coating with broad bandwidth, low loss, low reflectance, and a matched coffecient of thermal expansion. We present an AR coating for curved silicon optics comprised of subwavelength features cut into the lens surface with a custom three axis silicon dicing saw. These features constitute a metamaterial that behaves as a simple dielectric coating. We have fabricated and coated silicon lenses as large as 33.4 cm in diameter with coatings optimized for use between 125-165 GHz. Our design reduces average reflections to a few tenths of a percent for angles of incidence up to 30 deg. with low cross-polarization. We describe the design, tolerance, manufacture, and measurements of these coatings and present measurements of the optical properties of silicon at millimeter wavelengths at cryogenic and room temperatures. This coating and lens fabrication approach is applicable from centimeter to sub-millimeter wavelengths and can be used to fabricate coatings with greater than octave bandwidth.

  5. Large-aperture Wide-bandwidth Antireflection-coated Silicon Lenses for Millimeter Wavelengths

    NASA Technical Reports Server (NTRS)

    Datta, R.; Munson, C. D.; Niemack, M. D.; McMahon, J. J.; Britton, J.; Wollack, Edward J.; Beall, J.; Devlin, M. J.; Fowler, J.; Gallardo, P.; Hubmayr, J.; Irwin, K.; Newburgh, L.; Nibarger, J. P.; Page, L.; Quijada, Manuel A.; Schmitt, B. L.; Staggs, S. T.; Thornton, R.; Zhang, L.

    2013-01-01

    The increasing scale of cryogenic detector arrays for submillimeter and millimeter wavelength astrophysics has led to the need for large aperture, high index of refraction, low loss, cryogenic refracting optics. Silicon with n 3.4, low loss, and high thermal conductivity is a nearly optimal material for these purposes but requires an antireflection (AR) coating with broad bandwidth, low loss, low reflectance, and a matched coefficient of thermal expansion. We present an AR coating for curved silicon optics comprised of subwavelength features cut into the lens surface with a custom three-axis silicon dicing saw. These features constitute a metamaterial that behaves as a simple dielectric coating.We have fabricated silicon lenses as large as 33.4 cm in diameter with micromachined layers optimized for use between 125 and 165 GHz. Our design reduces average reflections to a few tenths of a percent for angles of incidence up to 30deg with low cross polarization.We describe the design, tolerance, manufacture, and measurements of these coatings and present measurements of the optical properties of silicon at millimeter wavelengths at cryogenic and room temperatures. This coating and lens fabrication approach is applicable from centimeter to submillimeter wavelengths and can be used to fabricate coatings with greater than octave bandwidth.

  6. Extending MIL-STD-1553 bandwidth: a study of impairments, EMI, and channel capacity

    NASA Astrophysics Data System (ADS)

    Hegarty, Michael G.

    2004-09-01

    This paper explores the possibility of increasing the data rates on existing MIL-STD-1553 networks beyond its current one megabit per second rate. A combination of empirical and theoretical methods is used in predicting the capacity of a MIL-STD-1553 network. The analysis begins with an assessment of the usable bandwidth in a 1553 network followed by the development of models to predict signal-to-noise ratios based on a transmit signal level that meets the emissions limits of MIL-STD-461 and a noise level that is representative of a real 1553 system. This paper presents the theoretical capacity limits for several 1553 network configurations. The results of the analysis predict that the theoretical capacity within a legacy MIL-STD-1553 system is expected to be several hundred megabits per second. The achievable rate depends on network configuration and usable bandwidth. Methods of approaching these theoretical capacity limits is not discussed in this paper, rather, this paper provides a framework and a baseline for the analysis of higher data rates over legacy MIL-STD-1553 networks.

  7. Modeling the dynamically tuned gyroscope in support of high-bandwidth capture loop design

    NASA Astrophysics Data System (ADS)

    May, David

    1999-07-01

    The 'dynamic tuning' of a dynamically tuned gyroscope (DTG) refers to a clever gimbal configuration that balances the torques from the support flexures with dynamic spring torques created by gimbal 'flutter' while the gyro rotor spins. This configuration allows the gyro rotor to spin to a 'free' rotor in two axes. The dynamics of a free rotor are widely known and easily summarized in the right-hand rule for gyro precession and a simple second order system equation with a natural frequency, known as the nutation frequency, as a function of the angular momentum and transverse inertia. Not much more is needed for design of capture loops for the DTG, as long as the bandwidth of the capture loop does not approach the nutation frequency of the gyro. However, the complete dynamical equations of motion of the DTG include other parameters such as windage, mistuning and friction torques that must be considered when designing capture loops with higher than nominal bandwidths. These equations, which are well known and widely published, are discussed in regard to capture loop design. The application of active nutation damping in the capture loop compensation is outlined. Typically results are presented.

  8. Fast Stiffness Mapping of Cells Using High-Bandwidth Atomic Force Microscopy.

    PubMed

    Wang, Andrew; Vijayraghavan, Karthik; Solgaard, Olav; Butte, Manish J

    2016-01-26

    The cytoskeleton controls cellular morphology and mediates the mechanical interactions between a cell and its environment. Atomic force microscopy (AFM) has the unique capability to map cytoskeletal mechanics and structures with nanometer resolution. However, whole-cell cytomechanical imaging with conventional AFM techniques is limited by low imaging speed. Here, we present fast nanomechanical mapping of cells using high-bandwidth AFM (HB-AFM), where >10(6) nanoindentation measurements were acquired in ∼10 min-a task that would take weeks to finish using conventional AFM. High-bandwidth measurements enabled capture of the entire tip-sample interaction for each tap on cells, engendering a new measurement ("force phase") that exceeds the contrast of conventional tapping mode and enabling spectral visualization of >10 harmonics. The abundance of measurements allowed discovery of subtle cytomechanical features, including the stiffness of fibers of the cellular spectrin network in situ. This approach bridges HB-AFM and high-harmonic imaging and opens future opportunities for measuring the dynamic mechanical properties of living cells. PMID:26554581

  9. Wide bandwidth transimpedance amplifier for extremely high sensitivity continuous measurements.

    PubMed

    Ferrari, Giorgio; Sampietro, Marco

    2007-09-01

    This article presents a wide bandwidth transimpedance amplifier based on the series of an integrator and a differentiator stage, having an additional feedback loop to discharge the standing current from the device under test (DUT) to ensure an unlimited measuring time opportunity when compared to switched discharge configurations while maintaining a large signal amplification over the full bandwidth. The amplifier shows a flat response from 0.6 Hz to 1.4 MHz, the capability to operate with leakage currents from the DUT as high as tens of nanoamperes, and rail-to-rail dynamic range for sinusoidal current signals independent of the DUT leakage current. Also available is a monitor output of the stationary current to track experimental slow drifts. The circuit is ideal for noise spectral and impedance measurements of nanodevices and biomolecules when in the presence of a physiological medium and in all cases where high sensitivity current measurements are requested such as in scanning probe microscopy systems. PMID:17902966

  10. Improving microwave antenna gain and bandwidth with phase compensation metasurface

    NASA Astrophysics Data System (ADS)

    Chen, Ke; Yang, Zhongjie; Feng, Yijun; Zhu, Bo; Zhao, Junming; Jiang, Tian

    2015-06-01

    Metasurface, as a planar version of artificial metamaterial, provide an effective way to manipulate electromagnetic wave propagation. Here, we present a transparent metasurface for compensating the out-of-phase radiation from a microstrip patch antenna to improve its radiation gain and bandwidth. Based on the equivalence principle of Huygens' surface, we propose metasurface composed of both inductive and capacitive resonant elements which could produce high transmission with variable phase characteristics. Such metasurface mounted on a patch antenna can transform the spherical-like phase profile generated from the patch into an in-phase planar one. A prototype antenna has been fabricated and validated the squeezed radiation pattern with suppressed sidelobes as well as enhanced impedance bandwidth due to strong near-field coupling. As operating at around 5.7 GHz, the proposed antenna may have potential application in wireless communication systems especially for point-to-point data transmission. It is believed that the design methodology could also be scaled to other frequency bands such as millimeter or terahertz wave.

  11. A wide bandwidth electrostatic field sensor for lightning research

    NASA Technical Reports Server (NTRS)

    Zaepfel, Klaus P.

    1989-01-01

    Data obtained from UHF radar observation of direct-lightning strikes to the NASA F-106B aircraft have indicated that most of the 690 strikes acquired during direct-strike lightning tests were triggered by the aircraft. As an aid in understanding the triggered lightning process, a wide bandwidth electric field measuring system was designed for the F-106B by implementing a clamped-detection signal processing concept originated at the Air Force Cambridge Research Lab in 1953. The detection scheme combines the signals from complementary stator pairs clamped to zero bolts at the exact moment when each stator pair is maximally shielded by the rotor, a process that restores the dc level lost by the charge amplifier. The system was implemented with four shutter-type field mills located at strategic points on the aircraft. The bandwidth of the system was determined in the laboratory to be from dc to over 100 Hz, whereas past designs had upper limits of 10 to 100 Hz. To obtain the undisturbed electric field vector and total aircraft charge, the airborne field mill system is calibrated by using techniques involving results from ground and flight calibrations of the F-106B, laboratory tests of a metallized model, and a finite difference time-domain electromagnetic computer code.

  12. A wide bandwidth electrostatic field sensor for lightning research

    NASA Technical Reports Server (NTRS)

    Zaepfel, K. P.

    1986-01-01

    Data obtained from UHF Radar observation of direct-lightning strikes to the NASA F-106B airplane have indicated that most of the 690 strikes acquired during direct-strike lightning tests were triggered by the aircraft. As an aid in understanding the triggered lightning process, a wide bandwidth electric field measuring system was designed for the F-106B by implementing a clamped-detection signal processing concept originated at the Air Force Cambridge Research Lab in 1953. The detection scheme combines the signals from complementary stator pairs clamped to zero volts at the exact moment when each stator pair is maximally shielded by the rotor, a process that restores the dc level lost by the charge amplifier. The new system was implemented with four shutter-type field mills located at strategic points on the airplane. The bandwidth of the new system was determined in the laboratory to be from dc to over 100 Hz, whereas past designs had upper limits of 10 Hz to 100 Hz. To obtain the undisturbed electric field vector and total aircraft charge, the airborne field mill system is calibrated by using techniques involving results from ground and flight calibrations of the F-106B, laboratory tests of a metallized model, and a finite-difference time-domain electromagnetic computer code.

  13. Flexible power and bandwidth allocation in mobile satellites

    NASA Astrophysics Data System (ADS)

    Keyes, L. A.

    The introduction of L-band mobile communication services by spot beam satellites creates a payload design challenge due to uncertainty in the location and size of the new market to be served. A combination of payload technologies that allow a flexible allocation of power and bandwidth to any portion of the coverage area is described. Power flexibility is achieved by a novel combination of a low-level beam-forming network and a matrix power module which ensures equal sharing of power among individual amplifiers. This eliminates the loss of efficiency and increased mass when an amplifier associated with a beam must be over-designed to meet uncertainties in power distribution between beams. Flexibility in allocation of bandwidth to beams is achieved by intermediate frequency subdivision of the L-band service categories defined by ITU. These spectral subdivisions are assigned to beams by an IF interconnect matrix having beam ports and filter ports as inputs and outputs, respectively. Two such filter switch matrices are required, one for the inbound L-band to feeder link transponder, and one for the outbound feeder link to L-band transponder.

  14. X-ray FEL with a meV bandwidth

    NASA Astrophysics Data System (ADS)

    Saldin, E. L.; Schneidmiller, E. A.; Shvyd'ko, Yu. V.; Yurkov, M. V.

    2001-12-01

    A new design for a single pass X-ray Self-Amplified Spontaneous Emission (SASE) FEL was proposed by Feldhaus et al. (Opt. Commun. 140 (1997) 341) and named "two-stage SASE FEL". The scheme consists of two undulators and an X-ray monochromator located between them. For the Angström wavelength range the monochromator can be realized using Bragg reflections from crystals. We propose a scheme of monochromator with a bandwidth of 20 meV for the 14.4 keV X-ray SASE FEL being developed in the framework of the TESLA linear collider project. The spectral bandwidth of the radiation from the two-stage SASE FEL (20 meV) is determined by the finite duration of the electron pulse. The shot-to-shot fluctuations of energy spectral density are dramatically reduced in comparison with the 100% fluctuations in a SASE FEL. The peak and average brilliance are three orders of magnitude higher than the values which could be reached by a conventional X-ray SASE FEL.

  15. Programmable noise bandwidth reduction by means of digital averaging

    NASA Technical Reports Server (NTRS)

    Poklemba, John J. (Inventor)

    1993-01-01

    Predetection noise bandwidth reduction is effected by a pre-averager capable of digitally averaging the samples of an input data signal over two or more symbols, the averaging interval being defined by the input sampling rate divided by the output sampling rate. As the averaged sample is clocked to a suitable detector at a much slower rate than the input signal sampling rate the noise bandwidth at the input to the detector is reduced, the input to the detector having an improved signal to noise ratio as a result of the averaging process, and the rate at which such subsequent processing must operate is correspondingly reduced. The pre-averager forms a data filter having an output sampling rate of one sample per symbol of received data. More specifically, selected ones of a plurality of samples accumulated over two or more symbol intervals are output in response to clock signals at a rate of one sample per symbol interval. The pre-averager includes circuitry for weighting digitized signal samples using stored finite impulse response (FIR) filter coefficients. A method according to the present invention is also disclosed.

  16. Bandwidth characteristics for the stepped conical-zoned antenna

    NASA Astrophysics Data System (ADS)

    Wiltse, James C.

    2002-07-01

    The stepped conical zoned lens antenna has better overall efficiency than a true lens, and provides an excellent antenna pattern. It also exhibits somewhat different bandwidth characteristics than the Fresnel zone plate antenna. This paper examines the frequency behavior in detail, particularly for microwave and millimeter-wave applications. For the usual zone plate antenna employed at microwave or millimeter wavelengths, path length adjustment (i.e., phase correction) is accomplished by cutting different depths (grooves) in a dielectric plate or by using two or more dielectrics having different dielectric constants. The new design uses a tilted cut in a flat dielectric plate, which more accurately matches the shape of a true lens and produces much lower phase error. The construction is still linear (i.e. spherical or hyperboloidal curves do not have to be cut), and can be made, for example, by a milling machine with a tilted bit. For a circular zone plate, the lens is a stepped conical shape. The phase correction steps are small, usually a few degrees, which is much smaller than for the typical Fresnel zone plate. The bandwidth characteristics are calculated for specific cases.

  17. Multi-Modulator for Bandwidth-Efficient Communication

    NASA Technical Reports Server (NTRS)

    Gray, Andrew; Lee, Dennis; Lay, Norman; Cheetham, Craig; Fong, Wai; Yeh, Pen-Shu; King, Robin; Ghuman, Parminder; Hoy, Scott; Fisher, Dave

    2009-01-01

    A modulator circuit board has recently been developed to be used in conjunction with a vector modulator to generate any of a large number of modulations for bandwidth-efficient radio transmission of digital data signals at rates than can exceed 100 Mb/s. The modulations include quadrature phaseshift keying (QPSK), offset quadrature phase-shift keying (OQPSK), Gaussian minimum-shift keying (GMSK), and octonary phase-shift keying (8PSK) with square-root raised-cosine pulse shaping. The figure is a greatly simplified block diagram showing the relationship between the modulator board and the rest of the transmitter. The role of the modulator board is to encode the incoming data stream and to shape the resulting pulses, which are fed as inputs to the vector modulator. The combination of encoding and pulse shaping in a given application is chosen to maximize the bandwidth efficiency. The modulator board includes gallium arsenide serial-to-parallel converters at its input end. A complementary metal oxide/semiconductor (CMOS) field-programmable gate array (FPGA) performs the coding and modulation computations and utilizes parallel processing in doing so. The results of the parallel computation are combined and converted to pulse waveforms by use of gallium arsenide parallel-to-serial converters integrated with digital-to-analog converters. Without changing the hardware, one can configure the modulator to produce any of the designed combinations of coding and modulation by loading the appropriate bit configuration file into the FPGA.

  18. Series-fed circularly polarized microstrip antennas with broad bandwidth

    NASA Astrophysics Data System (ADS)

    Mao, Shau-Gang; Chen, Shiou-Li; Yeh, Jen-Chun; Lin, Tien-Min

    2007-08-01

    A new series-fed circularly polarized antenna (SFCPA) in microstrip configuration, which consists of a traveling-wave-type crank-line antenna (CLA) and a resonant-type square-ring slot antenna (SRSA), is developed. Unlike the conventional crank-line (CL) antenna array with an open end or a resistive load, the proposed SFCPA uses the SRSA at the termination of the CLA and thus exhibits not only a broad circularly polarized (CP) bandwidth but also a large antenna gain. The characteristics of the SFCPA, including the leaky-wave radiation and the circular polarization, are examined in terms of the dispersion diagram and the current distribution. The SFCPA with the two-cell CLA and the terminated SRSA is fabricated and measured to demonstrate the 10-dB return loss and 3-dB axial ratio (AR) bandwidths of 34.3% and 30.5%, respectively. The frequency-scanning radiation patterns with a 5-7 dBi antenna gain are also presented in the operating band.

  19. Improving microwave antenna gain and bandwidth with phase compensation metasurface

    SciTech Connect

    Chen, Ke; Yang, Zhongjie; Feng, Yijun Zhu, Bo; Zhao, Junming; Jiang, Tian

    2015-06-15

    Metasurface, as a planar version of artificial metamaterial, provide an effective way to manipulate electromagnetic wave propagation. Here, we present a transparent metasurface for compensating the out-of-phase radiation from a microstrip patch antenna to improve its radiation gain and bandwidth. Based on the equivalence principle of Huygens’ surface, we propose metasurface composed of both inductive and capacitive resonant elements which could produce high transmission with variable phase characteristics. Such metasurface mounted on a patch antenna can transform the spherical-like phase profile generated from the patch into an in-phase planar one. A prototype antenna has been fabricated and validated the squeezed radiation pattern with suppressed sidelobes as well as enhanced impedance bandwidth due to strong near-field coupling. As operating at around 5.7 GHz, the proposed antenna may have potential application in wireless communication systems especially for point-to-point data transmission. It is believed that the design methodology could also be scaled to other frequency bands such as millimeter or terahertz wave.

  20. Ionospheric Coherence Bandwidth Measurements in the Lower VHF Frequency Range

    NASA Astrophysics Data System (ADS)

    Suszcynsky, D. M.; Light, M. E.; Pigue, M. J.

    2015-12-01

    The United States Department of Energy's Radio Frequency Propagation (RFProp) experiment consists of a satellite-based radio receiver suite to study various aspects of trans-ionospheric signal propagation and detection in four frequency bands, 2 - 55 MHz, 125 - 175 MHz, 365 - 415 MHz and 820 - 1100 MHz. In this paper, we present simultaneous ionospheric coherence bandwidth and S4 scintillation index measurements in the 32 - 44 MHz frequency range collected during the ESCINT equatorial scintillation experiment. 40-MHz continuous wave (CW) and 32 - 44 MHz swept frequency signals were transmitted simultaneously to the RFProp receiver suite from the Reagan Test Site at Kwajalein Atoll in the Marshall Islands (8.7° N, 167.7° E) in three separate campaigns during the 2014 and 2015 equinoxes. Results show coherence bandwidths as small as ~ 1 kHz for strong scintillation (S4 > 0.7) and indicate a high degree of ionospheric variability and irregularity on 10-m spatial scales. Spread-Doppler clutter effects arising from preferential ray paths to the satellite due to refraction off of isolated density irregularities are also observed and are dominant at low elevation angles. The results are compared to previous measurements and available scaling laws.

  1. An exponential time 2-approximation algorithm for bandwidth

    SciTech Connect

    Kasiviswanathan, Shiva; Furer, Martin; Gaspers, Serge

    2009-01-01

    The bandwidth of a graph G on n vertices is the minimum b such that the vertices of G can be labeled from 1 to n such that the labels of every pair of adjacent vertices differ by at most b. In this paper, we present a 2-approximation algorithm for the Bandwidth problem that takes worst-case {Omicron}(1.9797{sup n}) = {Omicron}(3{sup 0.6217n}) time and uses polynomial space. This improves both the previous best 2- and 3-approximation algorithms of Cygan et al. which have an {Omicron}*(3{sup n}) and {Omicron}*(2{sup n}) worst-case time bounds, respectively. Our algorithm is based on constructing bucket decompositions of the input graph. A bucket decomposition partitions the vertex set of a graph into ordered sets (called buckets) of (almost) equal sizes such that all edges are either incident on vertices in the same bucket or on vertices in two consecutive buckets. The idea is to find the smallest bucket size for which there exists a bucket decomposition. The algorithm uses a simple divide-and-conquer strategy along with dynamic programming to achieve this improved time bound.

  2. Emergent CSCW systems: the resolution and bandwidth of workplaces.

    PubMed

    Xiao, Yan; Seagull, F Jacob

    2007-06-01

    In any collaborative work settings, people naturally develop physical tools and associated work processes that support the management of the interdependencies in information, materials, and social needs. Field studies of management of operating rooms pointed out that collaborative work is supported by an infrastructure that is composed of mostly non-computerized, physical components. The supporting infrastructure is jointly maintained and exploited, with constantly evolving patterns of usage, in response to complexity of coordination needs and the uncertain environment. To represent status and plans, users seem to invent structures based both on idiosyncratic preferences and on negotiated symbols. The fluidity and ease of restructuring workplaces to support collaborative work may be explained in part by the high resolution and bandwidth of workplaces: a large number of ways in which workers could structure their work and a high capacity to convey rich information and meanings quickly to collaborators. We argue that to support health care workers, designers of computer supported cooperative work (CSCW) systems should learn how the physical and perceptual properties of workplaces are exploited, and that CSCW systems should be designed to allow maximum freedom of restructuring and reconfiguring as part of workplaces to enhance bandwidth and resolution of representation and communication. PMID:16822715

  3. The Effect of Pulse Shaping QPSK on Bandwidth Efficiency

    NASA Technical Reports Server (NTRS)

    Purba, Josua Bisuk Mubyarto; Horan, Shelia

    1997-01-01

    This research investigates the effect of pulse shaping QPSK on bandwidth efficiency over a non-linear channel. This investigation will include software simulations and the hardware implementation. Three kinds of filters: the 5th order Butterworth filter, the 3rd order Bessel filter and the Square Root Raised Cosine filter with a roll off factor (alpha) of 0.25,0.5 and 1, have been investigated as pulse shaping filters. Two different high power amplifiers, one a Traveling Wave Tube Amplifier (TWTA) and the other a Solid State Power Amplifier (SSPA) have been investigated in the hardware implementation. A significant improvement in the bandwidth utilization (rho) for the filtered data compared to unfiltered data through the non-linear channel is shown in the results. This method promises strong performance gains in a bandlimited channel when compared to unfiltered systems. This work was conducted at NMSU in the Center for Space Telemetering, and Telecommunications Systems in the Klipsch School of Electrical and Computer Engineering Department and is supported by a grant from the National Aeronautics and Space Administration (NASA) NAG5-1491.

  4. Comparison of effects of sonar bandwidth for underwater target classification

    NASA Astrophysics Data System (ADS)

    Azimi-Sadjadi, Mahmood R.; Yao, De; Li, Donghui; Jamshidi, Arta A.; Dobeck, Gerald J.

    2000-08-01

    In this paper, two different data sets which use linear FM incident signals with different bandwidths, namely 40 KHz and 80 KHz, are used for benchmarking. The goal is to study the effects of using larger bandwidth for underwater target classification. The classification system is formed of several subsystems including preprocessing, a subband decomposition suing wavelet packets, linear predictive coding in subbands, feature selection and neural network classifier. The classification performance is demonstrated on ten noisy realizations of the data sets formed by adding synthesized reverberation effects with 12 dB signal-to- reverberation ratio. The ROC and the error location plots for these dat sets are generated. To compare the generalization and robustness of the system on these data sets, the error and classification rate statistics are generated using Monte Carlo simulations on a large set of noisy data. The results point to the fact that the wideband sonar provides better robustness property. Three-aspect fusion is also adopted which yields almost perfect classification performance. These issues will be thoroughly studied and analyzed in this paper.

  5. Modulation bandwidth of spin torque oscillators under current modulation

    NASA Astrophysics Data System (ADS)

    Quinsat, M.; Garcia-Sanchez, F.; Jenkins, A. S.; Tiberkevich, V. S.; Slavin, A. N.; Buda-Prejbeanu, L. D.; Zeltser, A.; Katine, J. A.; Dieny, B.; Cyrille, M.-C.; Ebels, U.

    2014-10-01

    For practical applications of spin torque nano-oscillators (STNO), one of the most critical characteristics is the speed at which an STNO responds to variations of external control parameters, such as current or/and field. Theory predicts that this speed is limited by the amplitude relaxation rate Γp that determines the timescale over which the amplitude fluctuations are damped out. In this study, this limit is verified experimentally by analyzing the amplitude and frequency noise spectra of the output voltage signal when modulating an STNO by a microwave current. In particular, it is shown that due to the non-isochronous nature of the STNO the amplitude relaxation rate Γp determines not only the bandwidth of an amplitude modulation, but also the bandwidth of a frequency modulation. The presented experimental technique will be important for the optimisation of the STNO characteristics for applications in telecommunications or/and data storage and is applicable even in the case when the STNO output signal is only several times higher than noise.

  6. Modulation bandwidth of spin torque oscillators under current modulation

    SciTech Connect

    Quinsat, M.; Garcia-Sanchez, F.; Jenkins, A. S.; Buda-Prejbeanu, L. D.; Dieny, B.; Ebels, U.; Tiberkevich, V. S.; Slavin, A. N.; Zeltser, A.; Katine, J. A.; Cyrille, M.-C.

    2014-10-13

    For practical applications of spin torque nano-oscillators (STNO), one of the most critical characteristics is the speed at which an STNO responds to variations of external control parameters, such as current or/and field. Theory predicts that this speed is limited by the amplitude relaxation rate Γ{sub p} that determines the timescale over which the amplitude fluctuations are damped out. In this study, this limit is verified experimentally by analyzing the amplitude and frequency noise spectra of the output voltage signal when modulating an STNO by a microwave current. In particular, it is shown that due to the non-isochronous nature of the STNO the amplitude relaxation rate Γ{sub p} determines not only the bandwidth of an amplitude modulation, but also the bandwidth of a frequency modulation. The presented experimental technique will be important for the optimisation of the STNO characteristics for applications in telecommunications or/and data storage and is applicable even in the case when the STNO output signal is only several times higher than noise.

  7. Unmanned Aircraft System Control and ATC Communications Bandwidth Requirements

    NASA Technical Reports Server (NTRS)

    Henriksen, Steve

    2008-01-01

    There are significant activities taking place to establish the procedures and requirements for safe and routine operation of unmanned aircraft systems (UAS) in the National Airspace System (NAS). Among the barriers to overcome in achieving this goal is the lack of sufficient frequency spectrum necessary for the UAS control and air traffic control (ATC) communications links. This shortcoming is compounded by the fact that the UAS control communications links will likely be required to operate in protected frequency spectrum, just as ATC communications links are, because they relate to "safety and regularity of flight." To support future International Telecommunications Union (ITU) World Radio Conference (WRC) agenda items concerning new frequency allocations for UAS communications links, and to augment the Future Communications Study (FCS) Technology Evaluation Group efforts, NASA Glenn Research Center has sponsored a task to estimate the UAS control and ATC communications bandwidth requirements for safe, reliable, and routine operation of UAS in the NAS. This report describes the process and results of that task. The study focused on long-term bandwidth requirements for UAS approximately through 2030.

  8. Not Accepted by the Family: "Being Difficult" or "Being Different"?

    ERIC Educational Resources Information Center

    Komter, Aafke; Voorpostel, Marieke; Pels, Trees

    2011-01-01

    Using data from the Netherlands Kinship Panel Study (NKPS) and combining a quantitative approach and a qualitative approach (N = 8,148 and n = 43, respectively), this study investigates the mechanisms associated with a lack of acceptance by one's family. From the total NKPS sample, 12.1% did not feel (entirely) accepted by their family. The…

  9. Using ultra narrow bandwidth to overcome traditional problems with distribution line carrier

    SciTech Connect

    Hunt, P.C.; Hunt, L.R.

    1995-12-31

    It has long been common knowledge among communication engineers that wide bandwidth signals require more energy to overcome noise than do narrow band signals. This is why, during adverse conditions Morse code radio communications can get through when voice can`t. To achieve similar range: A television transmitter (6000 kHz bandwidth) requires 200,000 watts; A music broadcast transmitter (60 kHz bandwidth) requires 2000 watts; A voice only transmitter (3 kHz bandwidth) requires 100 watts. Carry this principle to extremes: An Ultra Narrow Bandwidth (UNB) transmitter (.00001 kHz bandwidth) requires .003 watts. This paper explores the advantages of using Ultra Narrow Bandwidth (UNB) in power line carrier systems. Using an Automatic Meter Reading System as an example, the authors explore how UNB allows (or sometimes requires) a change in system architecture, which creates further advantages.

  10. Baby-Crying Acceptance

    NASA Astrophysics Data System (ADS)

    Martins, Tiago; de Magalhães, Sérgio Tenreiro

    The baby's crying is his most important mean of communication. The crying monitoring performed by devices that have been developed doesn't ensure the complete safety of the child. It is necessary to join, to these technological resources, means of communicating the results to the responsible, which would involve the digital processing of information available from crying. The survey carried out, enabled to understand the level of adoption, in the continental territory of Portugal, of a technology that will be able to do such a digital processing. It was used the TAM as the theoretical referential. The statistical analysis showed that there is a good probability of acceptance of such a system.

  11. High acceptance recoil polarimeter

    SciTech Connect

    The HARP Collaboration

    1992-12-05

    In order to detect neutrons and protons in the 50 to 600 MeV energy range and measure their polarization, an efficient, low-noise, self-calibrating device is being designed. This detector, known as the High Acceptance Recoil Polarimeter (HARP), is based on the recoil principle of proton detection from np[r arrow]n[prime]p[prime] or pp[r arrow]p[prime]p[prime] scattering (detected particles are underlined) which intrinsically yields polarization information on the incoming particle. HARP will be commissioned to carry out experiments in 1994.

  12. Paired comparisons of nonlinear frequency compression, extended bandwidth, and restricted bandwidth hearing-aid processing for children and adults with hearing loss

    PubMed Central

    Brennan, Marc A.; McCreery, Ryan; Kopun, Judy; Hoover, Brenda; Alexander, Joshua; Lewis, Dawna; Stelmachowicz, Patricia G.

    2014-01-01

    Background Preference for speech and music processed with nonlinear frequency compression and two controls (restricted and extended bandwidth hearing-aid processing) was examined in adults and children with hearing loss. Purpose Determine if stimulus type (music, sentences), age (children, adults) and degree of hearing loss influence listener preference for nonlinear frequency compression, restricted bandwidth and extended bandwidth. Research Design Within-subject, quasi-experimental study. Using a round-robin procedure, participants listened to amplified stimuli that were 1) frequency-lowered using nonlinear frequency compression, 2) low-pass filtered at 5 kHz to simulate the restricted bandwidth of conventional hearing aid processing, or 3) low-pass filtered at 11 kHz to simulate extended bandwidth amplification. The examiner and participants were blinded to the type of processing. Using a two-alternative forced-choice task, participants selected the preferred music or sentence passage. Study Sample Sixteen children (8–16 years) and 16 adults (19–65 years) with mild-to-severe sensorineural hearing loss. Intervention All subjects listened to speech and music processed using a hearing-aid simulator fit to the Desired Sensation Level algorithm v.5.0a (Scollie et al, 2005). Results Children and adults did not differ in their preferences. For speech, participants preferred extended bandwidth to both nonlinear frequency compression and restricted bandwidth. Participants also preferred nonlinear frequency compression to restricted bandwidth. Preference was not related to degree of hearing loss. For music, listeners did not show a preference. However, participants with greater hearing loss preferred nonlinear frequency compression to restricted bandwidth more than participants with less hearing loss. Conversely, participants with greater hearing loss were less likely to prefer extended bandwidth to restricted bandwidth. Conclusion Both age groups preferred access to

  13. Broad-bandwidth near-shot-noise-limited intensity noise suppression of a single-frequency fiber laser.

    PubMed

    Zhao, Qilai; Xu, Shanhui; Zhou, Kaijun; Yang, Changsheng; Li, Can; Feng, Zhouming; Peng, Mingying; Deng, Huaqiu; Yang, Zhongmin

    2016-04-01

    A significant broad-bandwidth near-shot-noise-limited intensity noise suppression of a single-frequency fiber laser is demonstrated based on a semiconductor optical amplifier (SOA) with optoelectronic feedback. By exploiting the gain saturation effect of the SOA and the intensity feedback loop, a maximum noise suppression of over 50 dB around the relaxation oscillation frequencies and a suppression bandwidth of up to 50 MHz are obtained. The relative intensity noise of -150  dB/Hz in the frequency range from 0.8 kHz to 50 MHz is achieved, which approaches the shot-noise limit. The obtained optical signal-to-noise ratio is more than 70 dB. This near-shot-noise-limited laser source shows important implications for the advanced fields of high-precision frequency stabilization, quantum key distribution, and gravitational wave detection. PMID:27192229

  14. Review of Recent Treatment Acceptability Research

    ERIC Educational Resources Information Center

    Carter, Stacy L.

    2007-01-01

    With recent increases in the use of positive approaches to treatment for individuals with developmental disabilities, it seems appropriate to review the variables that have been found to influence the acceptability of various treatments. Programmatic treatments for problematic behaviors that incorporate primarily positive (reinforcement)…

  15. Tandem photonic-crystal thin films surpassing Lambertian light-trapping limit over broad bandwidth and angular range

    SciTech Connect

    Oskooi, Ardavan Tanaka, Yoshinori; Noda, Susumu

    2014-03-03

    Random surface texturing of an optically thick film to increase the path length of scattered light rays, first proposed nearly thirty years ago, has thus far remained the most effective approach for photon absorption over the widest set of conditions. Here, using recent advances in computational electrodynamics, we describe a general strategy for the design of a silicon thin film applicable to photovoltaic cells based on a quasi-resonant approach to light trapping where two partially disordered photonic-crystal slabs, stacked vertically on top of each other, have large absorption that surpasses the Lambertian limit over a broad bandwidth and angular range.

  16. Fokker-Planck electron diffusion caused by an obliquely propagating electromagnetic wave packet of narrow bandwidth

    NASA Technical Reports Server (NTRS)

    Hizanidis, Kyriakos

    1989-01-01

    The relativistic motion of electrons in an intense electromagnetic wave packet propagating obliquely to a uniform magnetic field is analytically studied on the basis of the Fokker-Planck-Kolmogorov (FPK) approach. The wavepacket consists of circularly polarized electron-cyclotron waves. The dynamical system in question is shown to be reducible to one with three degrees of freedom. Within the framework of the Hamiltonian analysis the nonlinear diffusion tensor is derived, and it is shown that this tensor can be separated into zeroth-, first-, and second-order parts with respect to the relative bandwidth. The zeroth-order part describes diffusive acceleration along lines of constant unperturbed Hamiltonian. The second-order part, which corresponds to the longest time scale, describes diffusion across those lines. A possible transport theory is outlined on the basis of this separation of the time scales.

  17. Broad working bandwidth and "endlessly" single-mode guidance within hybrid silicon photonics.

    PubMed

    Bougot-Robin, K; Hugonin, J-P; Besbes, M; Benisty, H

    2015-08-01

    The successes of nonlinear photonics and hybrid silicon photonics with a growing variety of functional materials entail ever-enlarging bandwidths. It is best exemplified by parametric comb frequency generation. Such operation challenges the dielectric channel waveguide as the basis for guidance, because of the adverse advent of higher order modes at short wavelengths. Surprisingly, the popular mechanism of endlessly single-mode guidance [Opt. Lett.22, 961 (1997).] operating in photonic crystal fibers has not been transposed within silicon photonics yet. We outline here the strategy and potential of this approach within planar and hybrid silicon photonics, whereby in-plane and vertical confinement are shown to be amenable to near-single-mode behavior in the typical silicon band, i.e., λ=1.1  μm to ∼5  μm. PMID:26258345

  18. High Bandwidth Short Stroke Rotary Fast Tool Servo

    SciTech Connect

    Montesanti, R C; Trumper, D L

    2003-08-22

    This paper presents the design and performance of a new rotary fast tool servo (FTS) capable of developing the 40 g's tool tip acceleration required to follow a 5 micron PV sinusoidal surface at 2 kHz with a planned accuracy of 50 nm, and having a full stroke of 50 micron PV at lower frequencies. Tests with de-rated power supplies have demonstrated a closed-loop unity-gain bandwidth of 2 kHz with 20 g's tool acceleration, and we expect to achieve 40 g's with supplies providing {+-} 16 Amp to the Lorentz force actuator. The use of a fast tool servo with a diamond turning machine for producing non-axisymmetric or textured surfaces on a workpiece is well known. Our new rotary FTS was designed to specifically accommodate fabricating prescription textured surfaces on 5 mm diameter spherical target components for High Energy Density Physics experiments on the National Ignition Facility Laser (NIF).

  19. Wide-Bandwidth Capture of Wire-Scanner Signals

    SciTech Connect

    Gruchalla, Michael E.; Gilpatrick, John D.; Sedillo, James Daniel; Martinez, Derwin

    2012-05-16

    Integrated charge collected on the sense wires of wire-scanner systems utilized to determine beam profile is generally the parameter of interest. The LANSCE application requires capturing the charge information macropulse-by-macropulse with macropulse lengths as long as 700 {micro}s at a maximum macropulse rate of 120 Hz. Also, for the LANSCE application, it is required that the integration be performed in a manner that does not require integrator reset between macropulses. Due to the long macropulse which must be accommodated and the 8.33 ms minimum pulse period, a simple R-C integrator cannot be utilized since there is insufficient time between macropulses to allow the integrator to adequately recover. The application of wide analog bandwidth to provide accurate pulse-by-pulse capture of the wire signals with digital integration of the wire signals to determine captured charge at each macropulse in applications with comparatively long macropulses and high pulse repetition rates is presented.

  20. High-bandwidth continuous-flow arc furnace

    DOEpatents

    Hardt, David E.; Lee, Steven G.

    1996-01-01

    A high-bandwidth continuous-flow arc furnace for stream welding applications includes a metal mass contained in a crucible having an orifice. A power source charges an electrode for generating an arc between the electrode and the mass. The arc heats the metal mass to a molten state. A pressurized gas source propels the molten metal mass through the crucible orifice in a continuous stream. As the metal is ejected, a metal feeder replenishes the molten metal bath. A control system regulates the electrode current, shielding gas pressure, and metal source to provide a continuous flow of molten metal at the crucible orifice. Independent control over the electrode current and shield gas pressure decouples the metal flow temperature and the molten metal flow rate, improving control over resultant weld characteristics.

  1. High-bandwidth continuous-flow arc furnace

    DOEpatents

    Hardt, D.E.; Lee, S.G.

    1996-08-06

    A high-bandwidth continuous-flow arc furnace for stream welding applications includes a metal mass contained in a crucible having an orifice. A power source charges an electrode for generating an arc between the electrode and the mass. The arc heats the metal mass to a molten state. A pressurized gas source propels the molten metal mass through the crucible orifice in a continuous stream. As the metal is ejected, a metal feeder replenishes the molten metal bath. A control system regulates the electrode current, shielding gas pressure, and metal source to provide a continuous flow of molten metal at the crucible orifice. Independent control over the electrode current and shield gas pressure decouples the metal flow temperature and the molten metal flow rate, improving control over resultant weld characteristics. 4 figs.

  2. Techniques in molecular spectroscopy: from broad bandwidth to high resolution

    NASA Astrophysics Data System (ADS)

    Cossel, Kevin C.

    This thesis presents a range of different experiments all seeking to extended the capabilities of molecular spectroscopy and enable new applications. The new technique of cavity-enhanced direct frequency comb spectroscopy (CE-DFCS) provides a unique combination of broad bandwidth, high resolution, and high sensitivity that can be useful for a wide range of applications. Previous demonstrations of CE-DFCS were confined to the visible or near-infrared and operated over a limited bandwidth: for many applications it is desirable to increase the spectral coverage and to extend to the mid-infrared where strong, fundamental vibrational modes of molecules occur. There are several key requirements for CE-DFCS: a frequency comb source that provides broad bandwidth and high resolution, an optical cavity for high sensitivity, and a detection system capable of multiplex detection of the comb spectrum transmitted through the cavity. We first discuss comb sources with emphasis on the coherence properties of spectral broadening in nonlinear fiber and the development of a high-power frequency comb source in the mid-infrared based on an optical-parametric oscillator (OPO). To take advantage of this new mid-infrared comb source for spectroscopy, we also discuss the development of a rapid-scan Fourier-transform spectrometer (FTS). We then discuss the first demonstration of CE-DFCS with spectrally broadened light from a highly nonlinear fiber with the application to measurements of impurities in semiconductor manufacturing gases. We also cover our efforts towards extending CE-DFCS to the mid-infrared using the mid-infrared OPO and FTS to measure ppb levels of various gases important for breath analysis and atmospheric chemistry and highlight some future applications of this system. In addition to the study of neutral molecules, broad-bandwidth and high-resolution spectra of molecular ions are useful for astrochemistry where many of the observed molecules are ionic, for studying

  3. Development of high frequency and wide bandwidth Johnson noise thermometry

    SciTech Connect

    Crossno, Jesse; Liu, Xiaomeng; Kim, Philip; Ohki, Thomas A.; Fong, Kin Chung

    2015-01-12

    We develop a high frequency, wide bandwidth radiometer operating at room temperature, which augments the traditional technique of Johnson noise thermometry for nanoscale thermal transport studies. Employing low noise amplifiers and an analog multiplier operating at 2 GHz, auto- and cross-correlated Johnson noise measurements are performed in the temperature range of 3 to 300 K, achieving a sensitivity of 5.5 mK (110 ppm) in 1 s of integration time. This setup allows us to measure the thermal conductance of a boron nitride encapsulated monolayer graphene device over a wide temperature range. Our data show a high power law (T ∼ 4) deviation from the Wiedemann-Franz law above T ∼ 100 K.

  4. Fibre Bragg grating based accelerometer with extended bandwidth

    NASA Astrophysics Data System (ADS)

    Basumallick, Nandini; Biswas, Palas; Chakraborty, Rajib; Chakraborty, Sushanta; Dasgupta, Kamal; Bandyopadhyay, Somnath

    2016-03-01

    We have shown experimentally that the operable bandwidth of a fibre Bragg grating (FBG) based accelerometer can be extended significantly, without compromising its sensitivity, using a post-signal processing technique which involves frequency domain weighting. It has been demonstrated that using the above technique acceleration can be correctly interpreted even when the operating frequency encroaches on the region where the frequency response of the sensor is non-uniform. Two different excitation signals, which we often encounter in structural health monitoring applications, e.g. (i) a signal composed of multi-frequency components and (ii) a sinusoidal excitation with a frequency sweep, have been considered in our experiment. The results obtained have been compared with a piezo accelerometer.

  5. High bandwidth absorption spectroscopy with a dispersed supercontinuum source.

    PubMed

    Hult, Johan; Watt, Rosalynne S; Kaminski, Clemens F

    2007-09-01

    An optical gas sensor is presented, making use of a dispersed supercontinuum source, capable of acquiring broad bandwidth spectra at ultrahigh wavelength sweep and repetition rates. Wavelength sweeps from 1100 nm to 1700 nm can be performed in 800 ns at a spectral resolution of 40 pm. This is comparable to line-widths of molecular spectra at atmospheric pressure. Quantitative measurements are presented of CH(4) employing 80 nm wide sweeps over the P- Q- and R-branches of the 2nu(3) transition near 1665 nm, at rates exceeding 100 kHz. The effective acquisition rate is determined by the amount of averaging required, and the effect of this averaging on observed precision is investigated. PMID:19547496

  6. Investigation of Bandwidth-Efficient Coding and Modulation Techniques

    NASA Technical Reports Server (NTRS)

    Osborne, William P.

    1992-01-01

    The necessary technology was studied to improve the bandwidth efficiency of the space-to-ground communications network using the current capabilities of that network as a baseline. The study was aimed at making space payloads, for example the Hubble Space Telescope, more capable without the need to completely redesign the link. Particular emphasis was placed on the following concepts: (1) what the requirements are which are necessary to convert an existing standard 4-ary phase shift keying communications link to one that can support, as a minimum, 8-ary phase shift keying with error corrections applied; and (2) to determine the feasibility of using the existing equipment configurations with additional signal processing equipment to realize the higher order modulation and coding schemes.

  7. Transformation optics for antennas: why limit the bandwidth with metamaterials?

    NASA Astrophysics Data System (ADS)

    Quevedo-Teruel, Oscar; Tang, Wenxuan; Mitchell-Thomas, Rhiannon C.; Dyke, Amy; Dyke, Hazel; Zhang, Lianhong; Haq, Sajad; Hao, Yang

    2013-05-01

    In the last decade, a technique termed transformation optics has been developed for the design of novel electromagnetic devices. This method defines the exact modification of magnetic and dielectric constants required, so that the electromagnetic behaviour remains invariant after a transformation to a new coordinate system. Despite the apparently infinite possibilities that this mathematical tool introduces, one restriction has repeatedly recurred since its conception: limited frequency bands of operation. Here we circumvent this problem with the proposal of a full dielectric implementation of a transformed planar hyperbolic lens which retains the same focusing properties of an original curved lens. The redesigned lens demonstrates operation with high directivity and low side lobe levels for an ultra-wide band of frequencies, spanning over three octaves. The methodology proposed in this paper can be applied to revolutionise the design of many electromagnetic devices overcoming bandwidth limitations.

  8. Modulator based high bandwidth optical readout for HEP detectors

    NASA Astrophysics Data System (ADS)

    Drake, G.; Fernando, W. S.; Stanek, R. W.; Underwood, D. G.

    2013-02-01

    Optical links will be an integral part of future LHC experiments at various scales from coupled sensors to off-detector communication. We are investigating CW lasers and light modulators as an alternative to VCSELs. Light modulators are small, use less power, have high bandwidth, are reliable, have low bit error rates and are very rad-hard. We present the quality of the links at 10Gbps and the results of radiation hardness measurements for the modulators built based on LiNbO3, InP, and Si. Also we present results on modulator-based free space data links, steered by MEMS mirrors and optical feedback paths for the control loop.

  9. Transformation optics for antennas: why limit the bandwidth with metamaterials?

    PubMed Central

    Quevedo-Teruel, Oscar; Tang, Wenxuan; Mitchell-Thomas, Rhiannon C.; Dyke, Amy; Dyke, Hazel; Zhang, Lianhong; Haq, Sajad; Hao, Yang

    2013-01-01

    In the last decade, a technique termed transformation optics has been developed for the design of novel electromagnetic devices. This method defines the exact modification of magnetic and dielectric constants required, so that the electromagnetic behaviour remains invariant after a transformation to a new coordinate system. Despite the apparently infinite possibilities that this mathematical tool introduces, one restriction has repeatedly recurred since its conception: limited frequency bands of operation. Here we circumvent this problem with the proposal of a full dielectric implementation of a transformed planar hyperbolic lens which retains the same focusing properties of an original curved lens. The redesigned lens demonstrates operation with high directivity and low side lobe levels for an ultra-wide band of frequencies, spanning over three octaves. The methodology proposed in this paper can be applied to revolutionise the design of many electromagnetic devices overcoming bandwidth limitations. PMID:23712699

  10. High Bandwidth Optical Links for Micro-Satellite Support

    NASA Technical Reports Server (NTRS)

    Chao, Tien-Hsin (Inventor); Wilson, Keith E. (Inventor); Coste, Keith (Inventor)

    2016-01-01

    A method, systems, apparatus and device enable high bandwidth satellite communications. An onboard tracking detector, installed in a low-earth orbit satellite, detects a position of an incoming optical beam received/transmitted from a first ground station of one or more ground stations. Tracker electronics determine orientation information of the incoming optical beam based on the position. Control electronics receive the orientation information from the tracker electronics, and control a waveguide drive electronics. The waveguide drive electronics control a voltage that is provided to an electro-optic waveguide beam steering device. The electro-optic waveguide beam steering device steers an outgoing optical beam to one of the one or more ground stations based on the voltage.

  11. Sleep/doze controlled dynamic bandwidth allocation algorithms for energy-efficient passive optical networks.

    PubMed

    Dias, Maluge Pubuduni Imali; Wong, Elaine

    2013-04-22

    In this work, we present a comparative study of two just-in-time (JIT) dynamic bandwidth allocation algorithms (DBAs), designed to improve the energy-efficiency of the 10 Gbps Ethernet passive optical networks (10G-EPONs). The algorithms, termed just-in-time with varying polling cycle times (JIT) and just-in-time with fixed polling cycle times (J-FIT), are designed to achieve energy-savings when the idle time of an optical network unit (ONU) is less than the sleep-to-active transition time. This is made possible by a vertical-cavity surface-emitting laser (VCSEL) ONU that can transit into sleep or doze modes during its idle time. We evaluate the performance of the algorithms in terms of polling cycle time, power consumption, percentage of energy-savings, and average delay. The energy-efficiency of a VCSEL ONU that can transition into sleep or doze mode is compared to an always-ON distributed feedback (DFB) laser ONU. Simulation results indicate that both JIT and J-FIT DBA algorithms result in improved energy-efficiency whilst J-FIT performs better in terms of energy-savings at low network loads. The J-FIT DBA however, results in increased average delay in comparison to the JIT DBA. Nonetheless, this increase in average delay is within the acceptable range to support the quality of service (QoS) requirements of the next-generation access networks. PMID:23609699

  12. Coarse-Grain Bandwidth Estimation Scheme for Large-Scale Network

    NASA Technical Reports Server (NTRS)

    Cheung, Kar-Ming; Jennings, Esther H.; Sergui, John S.

    2013-01-01

    A large-scale network that supports a large number of users can have an aggregate data rate of hundreds of Mbps at any time. High-fidelity simulation of a large-scale network might be too complicated and memory-intensive for typical commercial-off-the-shelf (COTS) tools. Unlike a large commercial wide-area-network (WAN) that shares diverse network resources among diverse users and has a complex topology that requires routing mechanism and flow control, the ground communication links of a space network operate under the assumption of a guaranteed dedicated bandwidth allocation between specific sparse endpoints in a star-like topology. This work solved the network design problem of estimating the bandwidths of a ground network architecture option that offer different service classes to meet the latency requirements of different user data types. In this work, a top-down analysis and simulation approach was created to size the bandwidths of a store-and-forward network for a given network topology, a mission traffic scenario, and a set of data types with different latency requirements. These techniques were used to estimate the WAN bandwidths of the ground links for different architecture options of the proposed Integrated Space Communication and Navigation (SCaN) Network. A new analytical approach, called the "leveling scheme," was developed to model the store-and-forward mechanism of the network data flow. The term "leveling" refers to the spreading of data across a longer time horizon without violating the corresponding latency requirement of the data type. Two versions of the leveling scheme were developed: 1. A straightforward version that simply spreads the data of each data type across the time horizon and doesn't take into account the interactions among data types within a pass, or between data types across overlapping passes at a network node, and is inherently sub-optimal. 2. Two-state Markov leveling scheme that takes into account the second order behavior of

  13. A variable bandwidth assignment scheme for the Land Mobile Satellite experiment

    NASA Technical Reports Server (NTRS)

    Yan, T.-Y.; Li, V. O. K.

    1985-01-01

    The Mobile Satellite Experiment is a proposed experimental satellite-based communications network which provides data and voice communications to mobile terminals dispersed in geographically dispersed areas. In this paper, an analytical model is developed to calculate the performance of a Variable Bandwidth Assignment (VBA) Scheme. Under this scheme, the satellite channel bandwidth is dynamically reassigned so that a message may be transmitted in the shortest possible time. To transmit a long message, message channels will be reconfigured to have more bandwidth such that the transmission time is reduced, while to transmit a short message, the channel bandwidth will be shrunk such that the released bandwidth can be used to serve other messages. The model is illustrated with numerical examples. It is shown that a VBA scheme can achieve considerable improvement in transmission delays over a Fixed Bandwidth Assignment Scheme.

  14. Netest: A Tool to Measure the Maximum Burst Size, Available Bandwidth and Achievable Throughput

    SciTech Connect

    Jin, Guojun; Tierney, Brian

    2003-01-31

    Distinguishing available bandwidth and achievable throughput is essential for improving network applications' performance. Achievable throughput is the throughput considering a number of factors such as network protocol, host speed, network path, and TCP buffer space, where as available bandwidth only considers the network path. Without understanding this difference, trying to improve network applications' performance is like ''blind men feeling the elephant'' [4]. In this paper, we define and distinguish bandwidth and throughput, and debate which part of each is achievable and which is available. Also, we introduce and discuss a new concept - Maximum Burst Size that is crucial to the network performance and bandwidth sharing. A tool, netest, is introduced to help users to determine the available bandwidth, and provides information to achieve better throughput with fairness of sharing the available bandwidth, thus reducing misuse of the network.

  15. Dynamic Bandwidth Allocation with Effective Utilization of Polling Interval over WDM/TDM PON

    NASA Astrophysics Data System (ADS)

    Ni, Cuiping; Gan, Chaoqin; Gao, Ziyue

    2014-12-01

    WDM/TDM (wavelength-division multiplexing/time-division multiplexing) PON (passive optical network) appears to be an attractive solution for the next generation optical access networks. Dynamic bandwidth allocation (DBA) plays a crucial role in efficiently and fairly allocating the bandwidth among all users in WDM/TDM PON. In this paper, two dynamic bandwidth allocation schemes (DBA1 and DBA2) are proposed to eliminate the idle time of polling cycles (i.e. polling interval), improve bandwidth utilization and make full use of bandwidth resources. The two DBA schemes adjust the time slot of sending request information and make fair scheduling among users to achieve the effective utilization of polling interval in WDM/TDM PON. The simulation and theoretical analyses verify that the proposed schemes outperform the conventional DBA scheme. We also make comparisons between the two schemes in terms of bandwidth utilization and average packet delay to further demonstrate the effectiveness of the scheme of DBA2.

  16. Dressing the chopped-random-basis optimization: A bandwidth-limited access to the trap-free landscape

    NASA Astrophysics Data System (ADS)

    Rach, N.; Müller, M. M.; Calarco, T.; Montangero, S.

    2015-12-01

    In quantum optimal control theory the success of an optimization algorithm is highly influenced by how the figure of merit to be optimized behaves as a function of the control field, i.e., by the control landscape. Constraints on the control field introduce local minima in the landscape—false traps—which might prevent an efficient solution of the optimal control problem. Rabitz et al. [Science 303, 1998 (2004), 10.1126/science.1093649] showed that local minima occur only rarely for unconstrained optimization. Here, we extend this result to the case of bandwidth-limited control pulses showing that in this case one can eliminate the false traps arising from the constraint. Based on this theoretical understanding, we modify the chopped-random-basis (CRAB) optimal control algorithm and show that this development exploits the advantages of both (unconstrained) gradient algorithms and of truncated basis methods, allowing one to always follow the gradient of the unconstrained landscape by bandwidth-limited control functions. We study the effects of additional constraints and show that for reasonable constraints the convergence properties are still maintained. Finally, we numerically show that this approach saturates the theoretical bound on the minimal bandwidth of the control needed to optimally drive the system.

  17. Scaling Mesa Indium Phosphide DHBTs to Record Bandwidths

    NASA Astrophysics Data System (ADS)

    Lobisser, Evan

    Indium phosphide heterojunction bipolar transistors are able to achieve higher bandwidths at a given feature size than transistors in the Silicon material system for a given feature size. Indium phosphide bipolar transistors demonstrate higher breakdown voltages at a given bandwidth than both Si bipolars and field effect transistors in the InP material system. The high bandwidth of InP HBTs results from both intrinsic material parameters and bandgap engineering through epitaxial growth. The electron mobility in the InGaAs base and saturation velocity in the InP collector are both approximately three times higher than their counterparts in the SiGe material system. Resistance of the base can be made very low due to the large offset in the valence band between the InP emitter and the InGaAs base, which allows the base to be doped on the order of 1020 cm-3 with negligible reduction in emitter injection efficiency. This thesis deals with type-I, NPN dual-heterojunction bipolar transistors. The emitters are InP, and the base is InGaAs. There is a thin (˜ 10 nm) n-type InGaAs "setback" region, followed by a chirped superlattice InGaAs/InAlAs grade to the InP collector. The setback, grade, and collector are all lightly doped n-type. The emitter and collector are contacted through thin (˜ 5 nm) heavily doped n-type InGaAs layers to reduce contact resistivity. The primary focus of this work is increasing the bandwidth of InP HBTs through the proportional scaling of the device dimensions, both layer thicknesses and junction areas, as well as the reduction of the contact resistivities associated with the transistor. Essentially, all RC time constants and transit times must be reduced by a factor of two to double a transistor's bandwidth. Chapter 2 describes in detail the scaling laws and design principles for high frequency bipolar transistor design. A low-stress, blanket sputter deposited composite emitter metal process was developed. Refractory metal base contacts were

  18. Sonic boom acceptability studies

    NASA Astrophysics Data System (ADS)

    Shepherd, Kevin P.; Sullivan, Brenda M.; Leatherwood, Jack D.; McCurdy, David A.

    1992-04-01

    The determination of the magnitude of sonic boom exposure which would be acceptable to the general population requires, as a starting point, a method to assess and compare individual sonic booms. There is no consensus within the scientific and regulatory communities regarding an appropriate sonic boom assessment metric. Loudness, being a fundamental and well-understood attribute of human hearing was chosen as a means of comparing sonic booms of differing shapes and amplitudes. The figure illustrates the basic steps which yield a calculated value of loudness. Based upon the aircraft configuration and its operating conditions, the sonic boom pressure signature which reaches the ground is calculated. This pressure-time history is transformed to the frequency domain and converted into a one-third octave band spectrum. The essence of the loudness method is to account for the frequency response and integration characteristics of the auditory system. The result of the calculation procedure is a numerical description (perceived level, dB) which represents the loudness of the sonic boom waveform.

  19. Sonic boom acceptability studies

    NASA Technical Reports Server (NTRS)

    Shepherd, Kevin P.; Sullivan, Brenda M.; Leatherwood, Jack D.; Mccurdy, David A.

    1992-01-01

    The determination of the magnitude of sonic boom exposure which would be acceptable to the general population requires, as a starting point, a method to assess and compare individual sonic booms. There is no consensus within the scientific and regulatory communities regarding an appropriate sonic boom assessment metric. Loudness, being a fundamental and well-understood attribute of human hearing was chosen as a means of comparing sonic booms of differing shapes and amplitudes. The figure illustrates the basic steps which yield a calculated value of loudness. Based upon the aircraft configuration and its operating conditions, the sonic boom pressure signature which reaches the ground is calculated. This pressure-time history is transformed to the frequency domain and converted into a one-third octave band spectrum. The essence of the loudness method is to account for the frequency response and integration characteristics of the auditory system. The result of the calculation procedure is a numerical description (perceived level, dB) which represents the loudness of the sonic boom waveform.

  20. Mixed integer nonlinear programming model of wireless pricing scheme with QoS attribute of bandwidth and end-to-end delay

    NASA Astrophysics Data System (ADS)

    Irmeilyana, Puspita, Fitri Maya; Indrawati

    2016-02-01

    The pricing for wireless networks is developed by considering linearity factors, elasticity price and price factors. Mixed Integer Nonlinear Programming of wireless pricing model is proposed as the nonlinear programming problem that can be solved optimally using LINGO 13.0. The solutions are expected to give some information about the connections between the acceptance factor and the price. Previous model worked on the model that focuses on bandwidth as the QoS attribute. The models attempt to maximize the total price for a connection based on QoS parameter. The QoS attributes used will be the bandwidth and the end to end delay that affect the traffic. The maximum goal to maximum price is achieved when the provider determine the requirement for the increment or decrement of price change due to QoS change and amount of QoS value.

  1. Minimum cost maximum flow algorithm for upstream bandwidth allocation in OFDMA passive optical networks

    NASA Astrophysics Data System (ADS)

    Wu, Yating; Kuang, Bin; Wang, Tao; Zhang, Qianwu; Wang, Min

    2015-12-01

    This paper presents a minimum cost maximum flow (MCMF) based upstream bandwidth allocation algorithm, which supports differentiated QoS for orthogonal frequency division multiple access passive optical networks (OFDMA-PONs). We define a utility function as the metric to characterize the satisfaction degree of an ONU on the obtained bandwidth. The bandwidth allocation problem is then formulated as maximizing the sum of the weighted total utility functions of all ONUs. By constructing a flow network graph, we obtain the optimized bandwidth allocation using the MCMF algorithm. Simulation results show that the proposed scheme improves the performance in terms of mean packet delay, packet loss ratio and throughput.

  2. Monolithic integration of high bandwidth waveguide coupled Ge photodiode in a photonic BiCMOS process

    NASA Astrophysics Data System (ADS)

    Lischke, S.; Knoll, D.; Zimmermann, L.

    2015-03-01

    Monolithic integration of photonic functionality in the frontend-of-line (FEOL) of an advanced microelectronics technology is a key step towards future communication applications. This combines photonic components such as waveguides, couplers, modulators, and photo detectors with high-speed electronics plus shortest possible interconnects crucial for high-speed performance. Integration of photonics into CMOS FEOL is therefore in development for quite some time reaching 90nm node recently [1]. However, an alternative to CMOS is high-performance BiCMOS, offering significant advantages for integrated photonics-electronics applications with regard to cost and RF performance. We already presented results of FEOL integration of photonic components in a high-performance SiGe:C BiCMOS baseline to establish a novel, photonic BiCMOS process. Process cornerstone is a local-SOI approach which allows us to fabricate SOI-based, thus low-loss photonic components in a bulk BiCMOS environment [2]. A monolithically integrated 10Gbit/sec Silicon modulator with driver was shown here [3]. A monolithically integrated 25Gbps receiver was presented in [4], consisting of 200GHz bipolar transistors and CMOS devices, low-loss waveguides, couplers, and highspeed Ge photo diodes showing 3-dB bandwidth of 35GHz, internal responsivity of more than 0.6A/W at λ= 1.55μm, and ~ 50nA dark current at 1V. However, the BiCMOS-given thermal steps cause a significant smearing of the Germanium photo diodes doping profile, limiting the photo diode performance. Therefore, we introduced implantation of non-doping elements to overcome such limiting factors, resulting in photo diode bandwidths of more than 50GHz even under the effect of thermal steps necessary when the diodes are integrated in a high performance BiCMOS process.

  3. Spectral analysis of pair-correlation bandwidth: application to cell biology images

    PubMed Central

    Binder, Benjamin J.; Simpson, Matthew J.

    2015-01-01

    Images from cell biology experiments often indicate the presence of cell clustering, which can provide insight into the mechanisms driving the collective cell behaviour. Pair-correlation functions provide quantitative information about the presence, or absence, of clustering in a spatial distribution of cells. This is because the pair-correlation function describes the ratio of the abundance of pairs of cells, separated by a particular distance, relative to a randomly distributed reference population. Pair-correlation functions are often presented as a kernel density estimate where the frequency of pairs of objects are grouped using a particular bandwidth (or bin width), Δ>0. The choice of bandwidth has a dramatic impact: choosing Δ too large produces a pair-correlation function that contains insufficient information, whereas choosing Δ too small produces a pair-correlation signal dominated by fluctuations. Presently, there is little guidance available regarding how to make an objective choice of Δ. We present a new technique to choose Δ by analysing the power spectrum of the discrete Fourier transform of the pair-correlation function. Using synthetic simulation data, we confirm that our approach allows us to objectively choose Δ such that the appropriately binned pair-correlation function captures known features in uniform and clustered synthetic images. We also apply our technique to images from two different cell biology assays. The first assay corresponds to an approximately uniform distribution of cells, while the second assay involves a time series of images of a cell population which forms aggregates over time. The appropriately binned pair-correlation function allows us to make quantitative inferences about the average aggregate size, as well as quantifying how the average aggregate size changes with time. PMID:26064605

  4. Reduction of large set data transmission using algorithmically corrected model-based techniques for bandwidth efficiency

    NASA Astrophysics Data System (ADS)

    Khair, Joseph Daniel

    Communication requirements and demands on deployed systems are increasing daily. This increase is due to the desire for more capability, but also, due to the changing landscape of threats on remote vehicles. As such, it is important that we continue to find new and innovative ways to transmit data to and from these remote systems, consistent with this changing landscape. Specifically, this research shows that data can be transmitted to a remote system effectively and efficiently with a model-based approach using real-time updates, called Algorithmically Corrected Model-based Technique (ACMBT), resulting in substantial savings in communications overhead. To demonstrate this model-based data transmission technique, a hardware-based test fixture was designed and built. Execution and analysis software was created to perform a series of characterizations demonstrating the effectiveness of the new transmission method. The new approach was compared to a traditional transmission approach in the same environment, and the results were analyzed and presented. A Figure of Merit (FOM) was devised and presented to allow standardized comparison of traditional and proposed data transmission methodologies alongside bandwidth utilization metrics. The results of this research have successfully shown the model-based technique to be feasible. Additionally, this research has opened the trade space for future discussion and implementation of this technique.

  5. Bandwidth Efficient Modulation and Coding Techniques for NASA's Existing Ku/Ka-Band 225 MHz Wide Service

    NASA Technical Reports Server (NTRS)

    Gioannini, Bryan; Wong, Yen; Wesdock, John

    2005-01-01

    The National Aeronautics and Space Administration (NASA) has recently established the Tracking and Data Relay Satellite System (TDRSS) K-band Upgrade Project (TKUP), a project intended to enhance the TDRSS Ku-band and Ka-band Single Access Return 225 MHz (Ku/KaSAR-225) data service by adding the capability to process bandwidth efficient signal design and to replace the White Sand Complex (WSC) KSAR high data rate ground equipment and high rate switches which are nearing obsolescence. As a precursor to this project, a modulation and coding study was performed to identify signal structures which maximized the data rate through the Ku/KaSAR-225 channel, minimized the required customer EIRP and ensured acceptable hardware complexity on the customer platform. This paper presents the results and conclusions of the TKUP modulation and coding study.

  6. Increasing the orbital angular momentum bandwidth of entangled photons

    NASA Astrophysics Data System (ADS)

    Romero, Jacquiline; Giovannini, Daniele; Franke-Arnold, Sonja; Barnett, Stephen M.; Padgett, Miles J.

    2012-09-01

    The bandwidth of any communication system, classical or quantum, is limited by the number of orthogonal states in which the information can be encoded. Quantum key distribution systems available commercially rely on the two-dimensional polarisation state of photons. Quantum computation has also been largely designed on the basis of qubits. However, a photon is endowed with other degrees of freedom, such as orbital angular momentum (OAM). OAM is an attractive basis to be used for quantum information because it is discrete and theoretically infinite-dimensional. This promises a higher information capacity per photon which can lead to more complex quantum computation protocols and more security and robustness for quantum cryptography. Entanglement of OAM naturally arises from spontaneous parametric down-conversion (SPDC). However, any practical experiment utilising the innately high-dimensional entanglement of the orbital angular momentum (OAM) state space of photons is subject to the modal capacity of the detection system. Only a finite subset of this space is accessible experimentally. Given such a constraint, we show that the number of measured, entangled OAM modes in photon pairs generated by SPDC can be increased by tuning the phase-matching conditions in the SPDC process. We achieve this by tuning the orientation angle of the nonlinear crystal generating the entangled photons.

  7. High resolution, high bandwidth global shutter CMOS area scan sensors

    NASA Astrophysics Data System (ADS)

    Faramarzpour, Naser; Sonder, Matthias; Li, Binqiao

    2013-10-01

    Global shuttering, sometimes also known as electronic shuttering, enables the use of CMOS sensors in a vast range of applications. Teledyne DALSA Global shutter sensors are able to integrate light synchronously across millions of pixels with microsecond accuracy. Teledyne DALSA offers 5 transistor global shutter pixels in variety of resolutions, pitches and noise and full-well combinations. One of the recent generations of these pixels is implemented in 12 mega pixel area scan device at 6 um pitch and that images up to 70 frames per second with 58 dB dynamic range. These square pixels include microlens and optional color filters. These sensors also offer exposure control, anti-blooming and high dynamic range operation by introduction of a drain and a PPD reset gate to the pixel. The state of the art sense node design of Teledyne DALSA's 5T pixel offers exceptional shutter rejection ratio. The architecture is consistent with the requirements to use stitching to achieve very large area scan devices. Parallel or serial digital output is provided on these sensors using on-chip, column-wise analog to digital converters. Flexible ADC bit depth combined with windowing (adjustable region of interest, ROI) allows these sensors to run with variety of resolution/bandwidth combinations. The low power, state of the art LVDS I/O technology allows for overall power consumptions of less than 2W at full performance conditions.

  8. A scanning SQUID microscope with 200 MHz bandwidth

    NASA Astrophysics Data System (ADS)

    Talanov, Vladimir V.; Lettsome, Nesco M., Jr.; Borzenets, Valery; Gagliolo, Nicolas; Cawthorne, Alfred B.; Orozco, Antonio

    2014-04-01

    We developed a scanning DC SQUID microscope with novel readout electronics capable of wideband sensing of RF magnetic fields from 50 to 200 MHz and simultaneously providing closed-loop response at kHz frequencies. To overcome the 20 MHz bandwidth limitation of traditional closed-loop SQUIDs, a flux-modulated closed-loop simultaneously locks the SQUID quasi-static flux and flux-biases the SQUID for amplification of the RF flux up to Φ0/4 in amplitude. Demodulating the SQUID voltage with a double lock-in technique yields a signal representative of both the amplitude and phase of the RF flux. This provides 80 dB of a linear dynamic range with a flux noise density of 4 μΦ0 Hz-1/2 at 200 MHz for a Y Ba2Cu3O7 bi-crystal SQUID at 77 K. We describe the electronics’ performance and present images for RF magnetic field of the travelling wave in a coplanar waveguide, the standing wave in an open-circuited microstrip, and a surface mounted device antenna.

  9. Spatial frequency bandwidth used in the recognition of facial images.

    PubMed

    Näsänen, R

    1999-11-01

    The purpose of the study was to find out what spatial frequency information human observers use in the recognition of face images. Signal-to-noise ratio thresholds for the recognition of facial images were measured as a function of the centre spatial frequency of narrow-band additive spatial noise. The relative sensitivity of recognition to different spatial frequencies was derived from these results. The maximum sensitivity was found at 8-13 c/face width and the bandwidth was just under two octaves. Qualitatively similar results were obtained with stimuli in which Fourier phase was randomised within a narrow band of different centre spatial frequencies. This resulted in a considerable increase of energy threshold around 8 c/face width and less elsewhere. Further, contrast energy thresholds were measured as a function of the centre spatial frequency of band-pass filtered face images. As a function of object spatial frequency (c/face width), energy threshold first decreased and then increased. The lowest energy thresholds found around 10 c/face width were lower than the energy threshold for unfiltered images. This is what one would expect if face recognition is narrow-band, since band-pass filtered images of optimal centre spatial frequency do not contain unused contrast energy at low and high spatial frequencies. In conclusion, the results suggest that the recognition of facial images is tuned to a relatively narrow band (< 2 octaves) of mid object spatial frequencies. PMID:10748918

  10. Advanced processing for high-bandwidth sensor systems

    NASA Astrophysics Data System (ADS)

    Szymanski, John J.; Blain, Phil C.; Bloch, Jeffrey J.; Brislawn, Christopher M.; Brumby, Steven P.; Cafferty, Maureen M.; Dunham, Mark E.; Frigo, Janette R.; Gokhale, Maya; Harvey, Neal R.; Kenyon, Garrett; Kim, Won-Ha; Layne, J.; Lavenier, Dominique D.; McCabe, Kevin P.; Mitchell, Melanie; Moore, Kurt R.; Perkins, Simon J.; Porter, Reid B.; Robinson, S.; Salazar, Alfonso; Theiler, James P.; Young, Aaron C.

    2000-11-01

    Compute performance and algorithm design are key problems of image processing and scientific computing in general. For example, imaging spectrometers are capable of producing data in hundreds of spectral bands with millions of pixels. These data sets show great promise for remote sensing applications, but require new and computationally intensive processing. The goal of the Deployable Adaptive Processing Systems (DAPS) project at Los Alamos National Laboratory is to develop advanced processing hardware and algorithms for high-bandwidth sensor applications. The project has produced electronics for processing multi- and hyper-spectral sensor data, as well as LIDAR data, while employing processing elements using a variety of technologies. The project team is currently working on reconfigurable computing technology and advanced feature extraction techniques, with an emphasis on their application to image and RF signal processing. This paper presents reconfigurable computing technology and advanced feature extraction algorithm work and their application to multi- and hyperspectral image processing. Related projects on genetic algorithms as applied to image processing will be introduced, as will the collaboration between the DAPS project and the DARPA Adaptive Computing Systems program. Further details are presented in other talks during this conference and in other conferences taking place during this symposium.

  11. X-ray FEL with a meV bandwidth

    NASA Astrophysics Data System (ADS)

    Saldin, E. L.; Schneidmiller, E. A.; Shvyd'ko, Yu. V.; Yurkov, M. V.

    2001-08-01

    A new design for a single pass X-ray Self-Amplified Spontaneous Emission (SASE) FEL was proposed in [1] and named two-stage SASE FEL. The scheme consists of two undulators and an X-ray monochromator located between them. For the Angström wavelength range the monochromator could be realized using Bragg reflections from crystals. Proposed scheme of monochromator is illustrated for the 14.4 keV X-ray SASE FEL being developed in the framework of the TESLA linear collider project. The spectral bandwidth of the radiation from the two-stage SASE FEL (20 meV) is defined by the finite duration of the electron pulse. The shot-to-shot fluctuations of energy spectral density are dramatically reduced in comparison with the 100% fluctuations in a SASE FEL. The peak and average brilliance are by three orders of magnitude higher than the values which could be reached by a conventional X-ray SASE FEL.

  12. Satisfying customer bandwidth demand in IP data networks

    NASA Astrophysics Data System (ADS)

    Kogan, Yaakov; Kosal, Haluk; Maguluri, Gangaji; Ramachandran, Gomathi

    2001-07-01

    We introduce the notion of customer bandwidth fulfillment in IP data networks and provide a quantitative characterization of the fulfillment using measurements of the router uplink (link connecting a router to the backbone) utilization. The threshold for the uplink utilization is calculated for a given probability of customer fulfillment based on the normal approximation. We use three different stochastic models to prove the normal approximation for the distribution of the uplink utilization. The convergence to the Gaussian diffusion prcess is proved in the framework of the nonstationary exponential Benes buffer model. In a special case of an alternating renewal process, we show that the fulfillment can be evaluated based on measurements of the mean uplink utilization. We also prove that the distribution for the number of busy links in a large generalized Engset model is asymptotically normal that provides another justification of the normal approximation for the uplink utilization. We analyze 5-minutes measurements of the uplink utilization and show that their empirical distribution is close to normal.

  13. QoS routing via multiple paths using bandwidth reservation

    SciTech Connect

    Rao, N.S.V.; Batsell, S.G.

    1997-11-01

    The authors address the problem of computing a multipath, consisting of possibly overlapping paths, to transmit data from the source node s to the destination node d over a computer network while ensuring deterministic bounds on end-to-end delay or delivery rate. They consider two generic routing problems within the framework wherein bandwidth can be reserved, and guaranteed, once reserved, on various links of the communication network. The first problem requires that a message of finite length be transmitted from s to d within {tau} units of time. The second problem requires that a sequential message of r units be transmitted at a rate of {eta} such that maximum time difference between two units that are received out of order is no more than q. They propose a polynomial-time algorithm to the first problem based on an adaptation of the classical Ford-Fulkerson`s method. They present simulation results to illustrate the applicability of the proposed algorithm. They show the second problem to be NP-complete and propose a polynomial-time approximate solution.

  14. QoS routing via multiple paths using bandwidth reservation

    SciTech Connect

    Rao, N.S.V.; Batsell, S.G.

    1998-01-01

    The authors address the problem of computing a multipath, consisting of possibly overlapping paths, to transmit data from the source node s to the destination node d over a computer network while ensuring deterministic bounds on end-to-end delay or delivery rate.They consider two generic routing problems within the framework wherein bandwidth can be reserved, and guaranteed, once reserved, on various links of the communication network. The first problem requires that a message of finite length be transmitted from s to d within {tau} units of time. The second problem requires that a sequential message of r units be transmitted at a rate of {eta} such that maximum time difference between two units that are received out of order is no more than q. They propose a polynomial-time algorithm to the first problem based on an adaptation of the classical Ford-Fulkerson`s method. They present simulation results to illustrate the applicability of the proposed algorithm. They show the second problem to be NP-complete, and propose a polynomial-time approximately solution.

  15. Infinite bandwidth of a Mott-Hubbard insulator

    NASA Astrophysics Data System (ADS)

    Freericks, James; Cohn, Jeffrey; van Dongen, Peter; Krishnamurthy, Hulikal

    The conventional viewpoint of the strongly correlated electron metal-insulator transition is that a single band splits into two upper and lower Hubbard bands at the metal-insulator transition. Much work has investigated whether this transition is continuous or discontinuous. Here we focus on another aspect and ask the question of whether there are additional upper and lower Hubbard bands, which stretch all the way out to infinity|leading to an infinite bandwidth for the Mott insulator. While we are not yet able to provide a rigorous proof of this result, we use exact diagonalization studies on small clusters to motivate the existence of these additional bands, and we discuss some different methods that might be utilized to provide a rigorous proof of this result. Even though the extra upper and lower Hubbard bands have very low total spectral weight, those states are expected to have extremely long lifetimes, leading to a nontrivial contribution to the transport density of states for dc transport and modifying the high temperature limit for the electrical resistivity. JKF supported by the Department of Energy, Office of Basic Energy Sciences, under Grant No. DE-FG02-08ER46542, and by the McDevitt bequest at Georgetown University. HRK supported by the Indian Science Foundation.

  16. Numerical Models of Broad-Bandwidth Nanosecond Optical Parametric Oscillators

    SciTech Connect

    Bowers, M.S.; Gehr. R.J.; Smith, A.V.

    1998-10-22

    We present three new methods for modeling broad-bandwidth, nanosecond optitcal parametric oscillators in the plane-wave approximation. Each accounts for the group-velocity differences that determine the operating linewidth of unseeded optical parametric oscillators, and each allows the signal and idler waves to develop from quantum noise. The first two methods are based on split-step integration methods in which nonlinear mixing and propagation are calculated separately on alternate steps. One method relies on Fourier transforming handle propagation, wiih mixing integrated over a the fields between t and u to Az step: the other transforms between z and k= in the propagation step, with mixing integrated over At. The third method is based on expansion of the three optical fields in terms of their respective longitudinal empty cavity modes, taking into account the cavity boundary condi- tions. Equations describing the time development of the mode amplitudes are solved to yield the time dependence of the three output fields. These plane-wave models exclude diffractive effects, but can be readily extended to include them.

  17. Social value of high bandwidth networks: creative performance and education.

    PubMed

    Mansell, Robin; Foresta, Don

    2016-03-01

    This paper considers limitations of existing network technologies for distributed theatrical performance in the creative arts and for symmetrical real-time interaction in online learning environments. It examines the experience of a multidisciplinary research consortium that aimed to introduce a solution to latency and other network problems experienced by users in these sectors. The solution builds on the Multicast protocol, Access Grid, an environment supported by very high bandwidth networks. The solution is intended to offer high-quality image and sound, interaction with other network platforms, maximum user control of multipoint transmissions, and open programming tools that are flexible and modifiable for specific uses. A case study is presented drawing upon an extended period of participant observation by the authors. This provides a basis for an examination of the challenges of promoting technological innovation in a multidisciplinary project. We highlight the kinds of technical advances and cultural and organizational changes that would be required to meet demanding quality standards, the way a research consortium planned to engage in experimentation and learning, and factors making it difficult to achieve an open platform that is responsive to the needs of users in the creative arts and education sectors. PMID:26809576

  18. Antenna array bandwidth enhancement using polymeric nanocomposite substrate

    NASA Astrophysics Data System (ADS)

    Muhamad, W. A. W.; Ngah, R.; Jamlos, M. F.; Soh, P. J.; Jamlos, M. A.; Lago, H.

    2016-04-01

    A 4 × 2 array antenna is developed using a new nanocomposite polymeric magneto-dielectric substrate. The permittivity and permeability factors have been accounted in designing the proposed array antenna at the frequency of 2.6 GHz. A pure polydimethylsiloxane (P-PDMS) (ɛ r = 2.7) solution is mixed with ferrite III oxide (μ r = 1.2) to generate this new nanocomposite polymeric magneto-dielectric (NPMD) substrate. The NPMD surface is then hardened and located in between two P-PDMS layers. The 4 × 2 radiating elements are immersed to the top of P-PDMS layer, while SMA coaxial feeder is fed from underneath the ground layer. This sealing technique enabled the proposed antenna to be waterproof and flexible. This combination contributes to bandwidth enhancement of 52.65 %, size miniaturization of 176 × 156 mm2 and high gain of 10.8 dB. The measured results show a good agreement with simulations.

  19. High-Bandwidth Protein Analysis Using Solid-State Nanopores

    PubMed Central

    Larkin, Joseph; Henley, Robert Y.; Muthukumar, Murugappan; Rosenstein, Jacob K.; Wanunu, Meni

    2014-01-01

    High-bandwidth measurements of the ion current through hafnium oxide and silicon nitride nanopores allow the analysis of sub-30 kD protein molecules with unprecedented time resolution and detection efficiency. Measured capture rates suggest that at moderate transmembrane bias values, a substantial fraction of protein translocation events are detected. Our dwell-time resolution of 2.5 μs enables translocation time distributions to be fit to a first-passage time distribution derived from a 1D diffusion-drift model. The fits yield drift velocities that scale linearly with voltage, consistent with an electrophoretic process. Further, protein diffusion constants (D) are lower than the bulk diffusion constants (D0) by a factor of ∼50, and are voltage-independent in the regime tested. We reason that deviations of D from D0 are a result of confinement-driven pore/protein interactions, previously observed in porous systems. A straightforward Kramers model for this inhibited diffusion points to 9- to 12-kJ/mol interactions of the proteins with the nanopore. Reduction of μ and D are found to be material-dependent. Comparison of current-blockage levels of each protein yields volumetric information for the two proteins that is in good agreement with dynamic light scattering measurements. Finally, detection of a protein-protein complex is achieved. PMID:24507610

  20. A video transmission system for low-bandwidth remote driving

    SciTech Connect

    DePiero, F.W.; Noell, T.E. ); Gee, T.F. )

    1993-01-01

    Oak Ridge National Laboratory (ORNL) staff have developed a real-time video transmission system for low-bandwidth remote operations. The system supports both continuous transmission of video for remote driving and progressive transmission of still images. Inherent in the system design is a spatiotemporal limitation to the effects of channel errors. The average data rate of the system is 64,000 bits/s, a compression of approximately 1000:1 for the black-and-white National Television Standard Code video. The image quality of the transmissions is maintained at a level that supports the teleoperated driving of a High-Mobility Multipurpose Wheeled Vehicle at speeds of up to 15 mph on a moguled dirt tract. The system also provides video transmissions for a mission package on board the vehicle. The system supports dynamic image quality adjustments that allow the remote driver to adjust to changing scenery and viewing requirements. During driving, the system's nominal configuration had a frame rate of 4 Hz, a compression per frame of 125:1, and a resulting latency of [approx] 1s.

  1. A video transmission system for low-bandwidth remote driving

    SciTech Connect

    DePiero, F.W.; Noell, T.E.; Gee, T.F.

    1993-05-01

    Oak Ridge National Laboratory (ORNL) staff have developed a real-time video transmission system for low-bandwidth remote operations. The system supports both continuous transmission of video for remote driving and progressive transmission of still images. Inherent in the system design is a spatiotemporal limitation to the effects of channel errors. The average data rate of the system is 64,000 bits/s, a compression of approximately 1000:1 for the black-and-white National Television Standard Code video. The image quality of the transmissions is maintained at a level that supports the teleoperated driving of a High-Mobility Multipurpose Wheeled Vehicle at speeds of up to 15 mph on a moguled dirt tract. The system also provides video transmissions for a mission package on board the vehicle. The system supports dynamic image quality adjustments that allow the remote driver to adjust to changing scenery and viewing requirements. During driving, the system`s nominal configuration had a frame rate of 4 Hz, a compression per frame of 125:1, and a resulting latency of {approx} 1s.

  2. Optimizing bandwidth and dynamic range of lumped Josephson parametric amplifiers

    NASA Astrophysics Data System (ADS)

    Eddins, A.; Vijay, R.; Macklin, C.; Minev, Z.; Siddiqi, I.

    2013-03-01

    Superconducting parametric amplifiers have revolutionized the field of quantum measurement by providing high gain, ultra-low noise amplification. They have been used successfully for high-fidelity qubit state measurements, probing nano-mechanical resonators, quantum feedback, and for microwave quantum optics experiments. Though several designs exist, a simple and robust architecture is the Lumped Josephson Parametric Amplifier (LJPA). This device consists of a capacitively shunted SQUID directly coupled to a transmission line to form a low quality factor (Q) nonlinear resonator. We discuss amplifiers which can be tuned over the full 4-8 GHz band with 20-25 dB of gain and 10 - 50 MHz of signal bandwidth. However, similar to other parametric amplifiers employing a resonant circuit, the LJPA suffers from low dynamic range and has a -1 dB gain compression point of order -130 dBm. We explore new designs comprised of an array of SQUIDs to improve the dynamic range. We will present the results of numerical simulations and preliminary experiments. We will also briefly discuss improvements obtained from different biasing methods and packaging. This research was supported by the Army Research Office under a QCT grant.

  3. High bandwidth piezoresistive force probes with integrated thermal actuation

    PubMed Central

    Doll, Joseph C.; Pruitt, Beth L.

    2012-01-01

    We present high-speed force probes with on-chip actuation and sensing for the measurement of pN-scale forces at the microsecond time scale. We achieve a high resonant frequency in water (1–100 kHz) with requisite low spring constants (0.3–40 pN/nm) and low integrated force noise (1–100 pN) by targeting probe dimensions on the order of 300 nm thick, 1–2 μm wide and 30–200 μm long. Forces are measured using silicon piezoresistors while the probes are actuated thermally with an aluminum unimorph and silicon heater. The piezoresistive sensors are designed using open source numerical optimization code that incorporates constraints on operating temperature. Parylene passivation enables operation in ionic media and we demonstrate simultaneous actuation and sensing. The improved design and fabrication techniques that we describe enable a 10–20 fold improvement in force resolution or measurement bandwidth over prior piezoresistive cantilevers of comparable thickness. PMID:23175616

  4. The Application of Acceptance and Commitment Therapy to Problem Anger

    ERIC Educational Resources Information Center

    Eifert, Georg H.; Forsyth, John P.

    2011-01-01

    The goal of this paper is to familiarize clinicians with the use of Acceptance and Commitment Therapy (ACT) for problem anger by describing the application of ACT to a case of a 45-year-old man struggling with anger. ACT is an approach and set of intervention technologies that support acceptance and mindfulness processes linked with commitment and…

  5. A 15 MHz bandwidth, 60 V{sub pp}, low distortion power amplifier for driving high power piezoelectric transducers

    SciTech Connect

    Capineri, Lorenzo

    2014-10-01

    This paper presents the design and the realization of a linear power amplifier with large bandwidth (15 MHz) capable of driving low impedance ultrasonic transducers. The output current driving capability (up to 5 A) and low distortion makes it suitable for new research applications using high power ultrasound in the medical and industrial fields. The electronic design approach is modular so that the characteristics can be scaled according to specific applications and implementation details for the circuit layout are reported. Finally the characterization of the power amplifier module is presented.

  6. The Minimum bandwidth of narrowband spikes in solar flare decimetric radio waves

    NASA Astrophysics Data System (ADS)

    Messmer, Peter; Benz, Arnold O.

    2000-02-01

    The minimum and the mean bandwidth of individual narrowband spikes in two events in decimetric radio waves is determined by means of multi-resolution analysis. Spikes of a few tens of millisecond duration occur at decimetric/microwave wavelength in the particle acceleration phase of solar flares. A first method determines the dominant spike bandwidth scale based on their scalegram, the mean squared wavelet coefficient at each frequency scale. This allows to measure the scale bandwidth independently of heuristic spike selection criteria, e.g. manual selection. The major drawback is a low resolution in the bandwidth. To overcome this uncertainty, a feature detection algorithm and a criterion for spike shape in the time-frequency plane is applied to locate the spikes. In that case, the bandwidth is measured by fitting an assumed spike profile into the denoised data. The smallest FWHM bandwidth of spikes was found at 0.17% and 0.41% of the center frequency in the two events. Knowing the shortest relevant bandwidth of spikes, the slope of the Fourier power spectrum of this two events was determined and no resemblance to a Kolmogorov spectrum detected. Additionally the correlation between spike peak flux and bandwidth was examined.

  7. Bandwidth Management in Universities in Zimbabwe: Towards a Responsible User Base through Effective Policy Implementation

    ERIC Educational Resources Information Center

    Chitanana, Lockias

    2012-01-01

    This research was undertaken to investigate the issue of how to maximise or make efficient use of bandwidth. In particular, the research sought to find out about what universities in Zimbabwe are doing to manage their bandwidth. It was, therefore, appropriate to survey a sample of five universities and to catalogue their experiences. Results show…

  8. A Survey of Bandwidth Utilization: Case Study of Federal University of Technology Minna

    NASA Astrophysics Data System (ADS)

    Haq, A.; Bello Salau, H.; Aibinu, A. M.; Onwuka, E. N.

    2013-12-01

    The effective utilization of the limited scarce bandwidth resources allocated by a spectrum regulator usually the Nigerian Communications Commissions (NCC) in Nigeria universities is paramount in maximizing the usage of the expensive scarce bandwidth resources. A significant bandwidth allocation is needed in order to meet up with the challenges of the day and the task of networking, communicating and reaching the word in our universities. Therefore, bandwidth management becomes necessary and essential. This paper contributes in that direction by surveying the bandwidth utilization at Federal University of Technology Minna campus with the hope of proffering a general solution that can be adopted in Nigerian universities for effective bandwidth management. Also, factors that hindered the development of most Nigeria universities are also examined. The federal university of technology minna which is structured like all other universities in the country in terms of the bandwidth requirement was choosing as a case study for this research work. Furthermore, some policies which can be adopted in order to effectively manage the scarce bandwidth resources in Nigerian universities are also proposed.

  9. Acceptance Probability (P a) Analysis for Process Validation Lifecycle Stages.

    PubMed

    Alsmeyer, Daniel; Pazhayattil, Ajay; Chen, Shu; Munaretto, Francesco; Hye, Maksuda; Sanghvi, Pradeep

    2016-04-01

    This paper introduces an innovative statistical approach towards understanding how variation impacts the acceptance criteria of quality attributes. Because of more complex stage-wise acceptance criteria, traditional process capability measures are inadequate for general application in the pharmaceutical industry. The probability of acceptance concept provides a clear measure, derived from specific acceptance criteria for each quality attribute. In line with the 2011 FDA Guidance, this approach systematically evaluates data and scientifically establishes evidence that a process is capable of consistently delivering quality product. The probability of acceptance provides a direct and readily understandable indication of product risk. As with traditional capability indices, the acceptance probability approach assumes that underlying data distributions are normal. The computational solutions for dosage uniformity and dissolution acceptance criteria are readily applicable. For dosage uniformity, the expected AV range may be determined using the s lo and s hi values along with the worst case estimates of the mean. This approach permits a risk-based assessment of future batch performance of the critical quality attributes. The concept is also readily applicable to sterile/non sterile liquid dose products. Quality attributes such as deliverable volume and assay per spray have stage-wise acceptance that can be converted into an acceptance probability. Accepted statistical guidelines indicate processes with C pk > 1.33 as performing well within statistical control and those with C pk < 1.0 as "incapable" (1). A C pk > 1.33 is associated with a centered process that will statistically produce less than 63 defective units per million. This is equivalent to an acceptance probability of >99.99%. PMID:26024723

  10. Bandwidth skimming: a technique for cost-effective video on demand

    NASA Astrophysics Data System (ADS)

    Eager, Derek L.; Vernon, Mary K.; Zahorjan, John

    1999-12-01

    This paper proposes a new technique for on-demand delivery of streaming media. The idea is to hold in reserve, or `skim', a portion of the client reception bandwidth that is sufficiently small that display quality is not impacted significantly, and yet that is nonetheless enough to support substantial reductions in server and network bandwidth through near-optimal hierarchical client stream merging. In this paper we show that this objective is feasible, and we develop practical techniques that achieve it. The results indicate that server and network bandwidth can be reduced to on the order of the logarithm of the number of clients who are viewing the object, using a small `skim' (e.g., 15%) of client reception bandwidth. These low server and network bandwidths are achieved for every media file, while providing immediate service to each client, and without having to pre-load initial portions of the video at each client.

  11. Enhanced spectral efficiency using bandwidth switchable SAW filtering for mobile satellite communications systems

    NASA Technical Reports Server (NTRS)

    Peach, Robert; Malarky, Alastair

    1990-01-01

    Currently proposed mobile satellite communications systems require a high degree of flexibility in assignment of spectral capacity to different geographic locations. Conventionally this results in poor spectral efficiency which may be overcome by the use of bandwidth switchable filtering. Surface acoustic wave (SAW) technology makes it possible to provide banks of filters whose responses may be contiguously combined to form variable bandwidth filters with constant amplitude and phase responses across the entire band. The high selectivity possible with SAW filters, combined with the variable bandwidth capability, makes it possible to achieve spectral efficiencies over the allocated bandwidths of greater than 90 percent, while retaining full system flexibility. Bandwidth switchable SAW filtering (BSSF) achieves these gains with a negligible increase in hardware complexity.

  12. Effects of large laser bandwidth on stimulated Raman scattering instability in underdense plasma

    SciTech Connect

    Zhao, Yao; Yu, Lu-Le; Zheng, Jun; Weng, Su-Ming; Ren, Chuang; Liu, Chuan-Sheng; Sheng, Zheng-Ming E-mail: zhengming.sheng@strath.ac.uk

    2015-05-15

    The effects of laser bandwidth on stimulated Raman scattering (SRS) instability in underdense plasma are studied by particle-in-cell simulations. In the simulations, sinusoidal frequency modulation of the incident laser pulse is used. By changing the size of bandwidth, it is shown that the linear growth of SRS can be suppressed considerably, provided the laser bandwidth is much larger than the SRS linear growth rate. Simulations also show that by choosing the proper frequency modulation parameters or decreasing the linear growth rate of SRS, the inhibitory effects become more obvious. The plasma electron temperature tends to weaken the bandwidth effects especially when it is over a keV level. The laser bandwidth can only increase the time duration for linear growth but cannot diminish the instability completely.

  13. Out-of-Band 40 DB Bandwidth of EESS (Active) Spaceborne SARS

    NASA Technical Reports Server (NTRS)

    Huneycutt, Bryan L.

    2005-01-01

    This document presents a study of out of band (OOB) 40 dB bandwidth requirements of spaceborne SARs in the Earth Exploration-Satellite Service (active) and Space Research Service (active). The purpose of the document is to study the OOB 40 dB bandwidth requirements and compare the 40 dB bandwidth B-40 as measured in simulations with that calculated using the ITU-R Rec SM.1541 equations. The spectra roll-off and resulting OOB 40 dB bandwidth of the linear FM signal is affected by the time-bandwidth product and the rise/fall times. Typical values of these waveform characteristics are given for existing EESS (active) sensors.

  14. Adaptive low-bandwidth tracking of Galileo and Pioneer 10 carriers

    NASA Technical Reports Server (NTRS)

    Watola, D. A.

    1992-01-01

    In the Deep Space Network, tracking of residual carrier phase typically occurs with a fixed-bandwidth phase-locked loop using a bandwidth sufficiently wide to prevent loss of lock under worst-case conditions of signal dynamics, received signal phase noise, and receiver phase noise. Much of the time, however, such a high bandwidth is not required and may inflict unnecessarily heavy penalties on loop signal-to-noise ratios. This article describes a technique for improving tracking performance by permitting initial tracking at narrow bandwidths and gradually widening the loop as needed. The cost is a requirement for signal buffering, which is relatively inexpensive for low data rate applications. Results based on off-line processing of recorded carrier data from Galileo and Pioneer 10 are presented, and show potential 10-16 dB gains in loop SNR over worst-case fixed-bandwidth tracking.

  15. Broad-Bandwidth FPGA-Based Digital Polyphase Spectrometer

    NASA Technical Reports Server (NTRS)

    Jamot, Robert F.; Monroe, Ryan M.

    2012-01-01

    With present concern for ecological sustainability ever increasing, it is desirable to model the composition of Earth s upper atmosphere accurately with regards to certain helpful and harmful chemicals, such as greenhouse gases and ozone. The microwave limb sounder (MLS) is an instrument designed to map the global day-to-day concentrations of key atmospheric constituents continuously. One important component in MLS is the spectrometer, which processes the raw data provided by the receivers into frequency-domain information that cannot only be transmitted more efficiently, but also processed directly once received. The present-generation spectrometer is fully analog. The goal is to include a fully digital spectrometer in the next-generation sensor. In a digital spectrometer, incoming analog data must be converted into a digital format, processed through a Fourier transform, and finally accumulated to reduce the impact of input noise. While the final design will be placed on an application specific integrated circuit (ASIC), the building of these chips is prohibitively expensive. To that end, this design was constructed on a field-programmable gate array (FPGA). A family of state-of-the-art digital Fourier transform spectrometers has been developed, with a combination of high bandwidth and fine resolution. Analog signals consisting of radiation emitted by constituents in planetary atmospheres or galactic sources are downconverted and subsequently digitized by a pair of interleaved analog-to-digital converters (ADCs). This 6-Gsps (gigasample per second) digital representation of the analog signal is then processed through an FPGA-based streaming fast Fourier transform (FFT). Digital spectrometers have many advantages over previously used analog spectrometers, especially in terms of accuracy and resolution, both of which are particularly important for the type of scientific questions to be addressed with next-generation radiometers.

  16. Fixed tile rate codec for bandwidth saving in video processors

    NASA Astrophysics Data System (ADS)

    Lachine, Vladimir; Dinh, Chon-Tam Le; Le, Dinh Kha; Wong, Jeffrey

    2014-02-01

    The paper presents an image compression circuit for bandwidth saving in video display processors. This is intra frame tile based compression algorithm offering visually lossless quality for compression rates between 1.5 and 2.5. RGB and YCbCr (4:4:4, 4:2:2 and 4:2:0) video formats are supported for 8/10 bits video signals. The Band Width Compressor (BWC) consists of Lossless Compressor (LC) and Quantization Compressor (QC) that generate output bit streams for tiles of pixels. Size of output bit stream generated for a tile by the LC may be less or greater than a required size of output memory block. The QC generates bit stream that always fits output memory block of the required size. The output bit stream generated by the LC is transmitted if its size is less than the required size of the output memory block. Otherwise, the output bit stream generated by the QC is transmitted. The LC works on pixel basis. A difference between original and predicted pixel's values for each pixel of a tile is encoded as prefix and suffix. The prefix is encoded by means of variable length code, and suffix is encoded as is. The QC divides a tile of pixels on a set of blocks and quantizes pixels of each block independently of the other blocks. The number of quantization bits for all pixels of a block depends on standard deviation calculated over the block. A difference between pixel's value and average value over the block is quantized and transmitted.

  17. User Acceptance of Long-Term Evolution (LTE) Services: An Application of Extended Technology Acceptance Model

    ERIC Educational Resources Information Center

    Park, Eunil; Kim, Ki Joon

    2013-01-01

    Purpose: The aim of this paper is to propose an integrated path model in order to explore user acceptance of long-term evolution (LTE) services by examining potential causal relationships between key psychological factors and user intention to use the services. Design/methodology/approach: Online survey data collected from 1,344 users are analysed…

  18. Acceptance- versus Change-Based Pain Management: The Role of Psychological Acceptance

    ERIC Educational Resources Information Center

    Blacker, Kara J.; Herbert, James D.; Forman, Evan M.; Kounios, John

    2012-01-01

    This study compared two theoretically opposed strategies for acute pain management: an acceptance-based and a change-based approach. These two strategies were compared in a within-subjects design using the cold pressor test as an acute pain induction method. Participants completed a baseline pain tolerance assessment followed by one of the two…

  19. Accepters and Rejecters of Counseling.

    ERIC Educational Resources Information Center

    Rose, Harriett A.; Elton, Charles F.

    Personality differences between students who accept or reject proffered counseling assistance were investigated by comparing personality traits of 116 male students at the University of Kentucky who accepted or rejected letters of invitation to group counseling. Factor analysis of Omnibus Personality Inventory (OPI) scores to two groups of 60 and…

  20. Cone penetrometer acceptance test report

    SciTech Connect

    Boechler, G.N.

    1996-09-19

    This Acceptance Test Report (ATR) documents the results of acceptance test procedure WHC-SD-WM-ATR-151. Included in this report is a summary of the tests, the results and issues, the signature and sign- off ATP pages, and a summarized table of the specification vs. ATP section that satisfied the specification.

  1. Patients’ acceptance of corticotomy-assisted orthodontics

    PubMed Central

    Zawawi, Khalid H

    2015-01-01

    Objective To study patients’ acceptance of corticotomy-assisted orthodontics as a treatment option. Methods Adult patients seeking orthodontic treatment were asked to complete two sets of questionnaires; the first set included questions about age, sex, and level of education and general questions about orthodontic treatment; and the second set was related to the corticotomy-assisted orthodontics. Before answering the corticotomy questions, a brief description of the clinical procedure was explained and photographs of an actual procedure were shown. Results A total of 150 subjects were approached and 129 (86%) agreed to answer the questionnaires (72 male and 57 female patients). Of these, only 3.1% did hear about corticotomy and 7.8% selected corticotomy instead of extraction. Fear from the surgery (53.2%) was the most frequent reason for not selecting corticotomy followed by fear from pain (36.9%). The acceptance of corticotomy between males and females was similar. No relationship was found between the level of education and prior knowledge of the procedure, P=0.857. Prior knowledge about corticotomy was not a factor in selecting it as a treatment option (P=0.556) to reduce the treatment time (P=0.427). Conclusion The acceptance of corticotomy-assisted orthodontics as a treatment option was low. Fear from the surgery was the main reason for not selecting it. The acceptance of corticotomy-assisted orthodontics was not related to patient’s level of education or sex. PMID:26316719

  2. High-Density, High-Bandwidth, Multilevel Holographic Memory

    NASA Technical Reports Server (NTRS)

    Chao, Tien-Hsin

    2008-01-01

    A proposed holographic memory system would be capable of storing data at unprecedentedly high density, and its data transfer performance in both reading and writing would be characterized by exceptionally high bandwidth. The capabilities of the proposed system would greatly exceed even those of a state-of-the art memory system, based on binary holograms (in which each pixel value represents 0 or 1), that can hold .1 terabyte of data and can support a reading or writing rate as high as 1 Gb/s. The storage capacity of the state-of-theart system cannot be increased without also increasing the volume and mass of the system. However, in principle, the storage capacity could be increased greatly, without significantly increasing the volume and mass, if multilevel holograms were used instead of binary holograms. For example, a 3-bit (8-level) hologram could store 8 terabytes, or an 8-bit (256-level) hologram could store 256 terabytes, in a system having little or no more size and mass than does the state-of-the-art 1-terabyte binary holographic memory. The proposed system would utilize multilevel holograms. The system would include lasers, imaging lenses and other beam-forming optics, a block photorefractive crystal wherein the holograms would be formed, and two multilevel spatial light modulators in the form of commercially available deformable-mirror-device spatial light modulators (DMDSLMs) made for use in high speed input conversion of data up to 12 bits. For readout, the system would also include two arrays of complementary metal oxide/semiconductor (CMOS) photodetectors matching the spatial light modulators. The system would further include a reference-beam sterring device (equivalent of a scanning mirror), containing no sliding parts, that could be either a liquid-crystal phased-array device or a microscopic mirror actuated by a high-speed microelectromechanical system. Time-multiplexing and the multilevel nature of the DMDSLM would be exploited to enable writing

  3. Bandwidth optimization of femtosecond pure-rotational coherent anti-Stokes Raman scattering by pump/Stokes spectral focusing.

    DOE PAGESBeta

    Kearney, Sean Patrick

    2014-07-01

    A simple spectral focusing scheme for bandwidth optimization of gas-phase rotational coherent anti-Stokes Raman scattering (CARS) spectra is presented. The method is useful when femtosecond pump/Stokes preparation of the Raman coherence is utilized. The approach is of practical utility when working with laser pulses that are not strictly transform limited, or when windows or other sources of pulse chirp may be present in the experiment. A delay between the femtosecond preparation pulses is introduced to shift the maximum Raman preparation away from zero frequency and toward the Stokes or anti-Stokes side of the spectrum with no loss in total preparationmore » bandwidth. Shifts of 100 cm-1 or more are attainable and allow for enhanced detection of high-energy (150-300 cm-1) rotational Raman transitions at near transform-limited optimum sensitivity. A simple theoretical treatment for the case of identical pump and Stokes pulses with linear frequency chirp is presented. The approach is then demonstrated experimentally for typical levels of transform-limited laser performance obtained our laboratory with nonresonant CARS in argon and Raman-resonant spectra from a lean H2/air flat flame.« less

  4. Bandwidth optimization of femtosecond pure-rotational coherent anti-Stokes Raman scattering by pump/Stokes spectral focusing.

    SciTech Connect

    Kearney, Sean Patrick

    2014-07-01

    A simple spectral focusing scheme for bandwidth optimization of gas-phase rotational coherent anti-Stokes Raman scattering (CARS) spectra is presented. The method is useful when femtosecond pump/Stokes preparation of the Raman coherence is utilized. The approach is of practical utility when working with laser pulses that are not strictly transform limited, or when windows or other sources of pulse chirp may be present in the experiment. A delay between the femtosecond preparation pulses is introduced to shift the maximum Raman preparation away from zero frequency and toward the Stokes or anti-Stokes side of the spectrum with no loss in total preparation bandwidth. Shifts of 100 cm-1 or more are attainable and allow for enhanced detection of high-energy (150-300 cm-1) rotational Raman transitions at near transform-limited optimum sensitivity. A simple theoretical treatment for the case of identical pump and Stokes pulses with linear frequency chirp is presented. The approach is then demonstrated experimentally for typical levels of transform-limited laser performance obtained our laboratory with nonresonant CARS in argon and Raman-resonant spectra from a lean H2/air flat flame.

  5. Measuring the frequency-dependent attenuation in lossy material using large time-bandwidth product ultrasound signals

    NASA Astrophysics Data System (ADS)

    Gordon, Grant A.

    1999-06-01

    Broadband signals are commonly used in ultrasonic spectroscopy to measure the frequency dependent attenuation characteristics of lossy solid media. Compared to narrowband signals, broadband signals are preferred since they do not require tedious frequency scanning and extensive data reduction efforts. Typically these broadband signals take the form of a pulse. Although the spectral range of a pulse is wide, the spectral resolution is limited by the duration of the signal. By employing signals with large time- bandwidth-products, the overall accuracy and resolution of ultrasonic spectroscopy can be improved. Expressions for the interaction of longitudinal waves, with large time- bandwidth-product, and isotropic materials are developed. The approach is effective for evaluating material with signals optimized for a frequency resolution and range of interest, but can also be used when thin materials (approach to illustrate the improved accuracy of the new technique, detailing where diffraction correction and multiple echo effects can become significant. Measured attenuation spectra are presented for common plastic materials as well as for a castable polyurethane commonly used in ultrasonic transducer fabrication.

  6. Increased spectral bandwidths in nonlinear conversion processes by use of multicrystal designs.

    PubMed

    Brown, M

    1998-10-15

    The fourth-harmonic generation of broadband 243-nm radiation is reported. The broadband radiation is achieved by implementation of a multicrystal design to overcome spectral bandwidth limitations, and a plane-wave analysis is developed that shows increased spectral bandwidths for these designs. The fourth harmonic of a Cr:LiSAF laser operating at 972 nm is generated in beta-barium borate (BBO). The results demonstrate a spectral bandwidth at 243 nm more than five times broader than that which is expected from a single BBO crystal of equivalent length. PMID:18091854

  7. Acousto-optics bandwidth broadening in a Bragg cell based on arbitrary synthesized signal methods.

    PubMed

    Peled, Itay; Kaminsky, Ron; Kotler, Zvi

    2015-06-01

    In this work, we present the advantages of driving a multichannel acousto-optical deflector (AOD) with a digitally synthesized multifrequency RF signal. We demonstrate a significant bandwidth broadening of ∼40% by providing well-tuned phase control of the array transducers. Moreover, using a multifrequency, complex signal, we manage to suppress the harmonic deflections and return most of the spurious energy to the main beam. This method allows us to operate the AOD with more than an octave of bandwidth with negligible spurious energy going to the harmonic beams and a total bandwidth broadening of over 70%. PMID:26192666

  8. High bandwidth based on a tapped delay line equalization in visible light communications

    NASA Astrophysics Data System (ADS)

    Zhang, Minglun; Guo, Xujing; Zhu, Hetian; Wang, Chao; Bai, Xiaonan; Zhai, Xiangwen

    2015-08-01

    In the visible light communication, the white LED bandwidth severely limits the transmission rate of information. This paper presents an analog pre-equalization technology to compensate for the bandwidth of white LED. The technology not only can debug according to the actual channel changing, but also avoid the high costs of using FPGA technology. The pre-equalization technology is implemented by an analog circuit of tapped-delay-line, in the circuit we select an appropriate delay line and a digital to analog converter. In our LED visible light communication system, we can achieve a bandwidth of 150MHz which was proved theoretically in the paper.

  9. Bandwidth Study on Energy Use and Potential Energy Savings Opportunities in U.S. Petroleum Refining

    SciTech Connect

    Sabine Brueske, Caroline Kramer, Aaron Fisher

    2015-06-01

    Energy bandwidth studies of U.S. manufacturing sectors can serve as foundational references in framing the range (or bandwidth) of potential energy savings opportunities. This bandwidth study examines energy consumption and potential energy savings opportunities in U.S. petroleum refining. The study relies on multiple sources to estimate the energy used in nine individual process areas, representing 68% of sector-wide energy consumption. Energy savings opportunities for individual processes are based on technologies currently in use or under development; these potential savings are then extrapolated to estimate sector-wide energy savings opportunity.

  10. Bandwidth Study on Energy Use and Potential Energy Saving Opportunities in U.S. Chemical Manufacturing

    SciTech Connect

    Sabine Brueske, Caroline Kramer, Aaron Fisher

    2015-06-01

    Energy bandwidth studies of U.S. manufacturing sectors can serve as foundational references in framing the range (or bandwidth) of potential energy savings opportunities. This bandwidth study examines energy consumption and potential energy savings opportunities in U.S. chemical manufacturing. The study relies on multiple sources to estimate the energy used in the production of 74 individual chemicals, representing 57% of sector-wide energy consumption. Energy savings opportunities for individual chemicals and for 15 subsectors of chemicals manufacturing are based on technologies currently in use or under development; these potential savings are then extrapolated to estimate sector-wide energy savings opportunity.

  11. Improving precision in resonance ionization mass spectrometry : influence of laser bandwidth in uranium isotope ratio measurements.

    SciTech Connect

    Isselhardt, B. H.; Savina, M. R.; Knight, K. B.; Pellin, M. J.; Hutcheon, I. D.; Prussin, S. G.

    2011-03-01

    The use of broad bandwidth lasers with automated feedback control of wavelength was applied to the measurement of {sup 235}U/{sup 238}U ratios by resonance ionization mass spectrometry (RIMS) to decrease laser-induced isotopic fractionation. By broadening the bandwidth of the first laser in a three-color, three-photon ionization process from a bandwidth of 1.8 GHz to about 10 GHz, the variation in sequential relative isotope abundance measurements decreased from 10% to less than 0.5%. This procedure was demonstrated for the direct interrogation of uranium oxide targets with essentially no sample preparation.

  12. A Low Cross-Polarization Smooth-Walled Horn with Improved Bandwidth

    NASA Technical Reports Server (NTRS)

    Zeng, Lingzhen; Bennett, Charles L.; Chuss, David T.; Wollack, Edward J.

    2009-01-01

    Corrugated feed horns offer excellent beam symmetry, main beam efficiency, and cross-polar response over wide bandwidths, but can be challenging to fabricate. An easier-to-manufacture smooth-walled feed is explored that approximates these properties over a finite bandwidth. The design, optimization and measurement of a monotonically-profiled, smooth-walled scalar feedhorn with a diffraction-limited approximately 7 degrees full width at half maximum (FWHM) is presented. The feed was demonstrated to have low cross polarization (<-30 dB) across the frequency range 33-45 GHz (30% fractional bandwidth). A return loss better than -28 dB was measured across the band.

  13. Wide-bandwidth Pound-Drever-Hall locking through a single-sideband modulator.

    PubMed

    Gatti, Davide; Gotti, Riccardo; Sala, Tommaso; Coluccelli, Nicola; Belmonte, Michele; Prevedelli, Marco; Laporta, Paolo; Marangoni, Marco

    2015-11-15

    An integrated single-sideband modulator is used as the sole wide-bandwidth frequency actuator in a Pound-Drever-Hall locking loop. Thanks to the large modulation bandwidth, the device enables a locking range of ±75 MHz and a control bandwidth of 5 MHz without the need for a second feedback loop. As applied to the coupling of an extended-cavity diode laser at 1.55 μm to a high-finesse optical cavity, the in-loop frequency noise spectral density reaches a minimum of 1 mHz/Hz(1/2) at 1 kHz. PMID:26565828

  14. A Low Cross-Polarization Smooth-Walled Horn with Improved Bandwidth

    NASA Technical Reports Server (NTRS)

    Zeng, Lingzhen; Bennette, Charles L.; Chuss, David T.; Wollack, Edward J.

    2009-01-01

    Corrugated feed horns offer excellent beam symmetry, main beam efficiency, and cross-polar response over wide bandwidths, but can be challenging to fabricate. An easier-to-manufacture smooth-walled feed is explored that approximates these properties over a finite bandwidth. The design, optimization and measurement of a monotonically-profiled, smooth-walled scalar feedhorn with a diffraction-limited approx. 14deg FWHM beam is presented. The feed was demonstrated to have low cross polarization (<-30 dB) across the frequency range 33-45 GHz (30% fractional bandwidth). A power reflection below -28 dB was measured across the band.

  15. Accepted scientific research works (abstracts).

    PubMed

    2014-01-01

    These are the 39 accepted abstracts for IAYT's Symposium on Yoga Research (SYR) September 24-24, 2014 at the Kripalu Center for Yoga & Health and published in the Final Program Guide and Abstracts. PMID:25645134

  16. L-286 Acceptance Test Record

    SciTech Connect

    HARMON, B.C.

    2000-01-14

    This document provides a detailed account of how the acceptance testing was conducted for Project L-286, ''200E Area Sanitary Water Plant Effluent Stream Reduction''. The testing of the L-286 instrumentation system was conducted under the direct supervision

  17. Hybrid femtosecond/picosecond rotational coherent anti-Stokes Raman scattering at flame temperatures using a second-harmonic bandwidth-compressed probe.

    PubMed

    Kearney, Sean P; Scoglietti, Daniel J

    2013-03-15

    We demonstrate an approach for picosecond probe-beam generation that enables hybrid femtosecond/picosecond pure-rotational coherent anti-Stokes Raman scattering (CARS) measurements in flames. Sum-frequency generation of bandwidth-compressed picosecond radiation from femtosecond pumps with phase-conjugate chirps provides probe pulses with energies in excess of 1 mJ that are temporally locked to the femtosecond pump/Stokes preparation. This method overcomes previous limitations on hybrid femtosecond/picosecond rotational CARS techniques, which have relied upon less efficient bandwidth-reduction processes that have generally resulted in prohibitively low probe energy for flame measurements. We provide the details of the second-harmonic approach and demonstrate the technique in near-adiabatic hydrogen/air flames. PMID:23503231

  18. Low-bandwidth and non-compute intensive remote identification of microbes from raw sequencing reads.

    PubMed

    Gautier, Laurent; Lund, Ole

    2013-01-01

    Cheap DNA sequencing may soon become routine not only for human genomes but also for practically anything requiring the identification of living organisms from their DNA: tracking of infectious agents, control of food products, bioreactors, or environmental samples. We propose a novel general approach to the analysis of sequencing data where a reference genome does not have to be specified. Using a distributed architecture we are able to query a remote server for hints about what the reference might be, transferring a relatively small amount of data. Our system consists of a server with known reference DNA indexed, and a client with raw sequencing reads. The client sends a sample of unidentified reads, and in return receives a list of matching references. Sequences for the references can be retrieved and used for exhaustive computation on the reads, such as alignment. To demonstrate this approach we have implemented a web server, indexing tens of thousands of publicly available genomes and genomic regions from various organisms and returning lists of matching hits from query sequencing reads. We have also implemented two clients: one running in a web browser, and one as a python script. Both are able to handle a large number of sequencing reads and from portable devices (the browser-based running on a tablet), perform its task within seconds, and consume an amount of bandwidth compatible with mobile broadband networks. Such client-server approaches could develop in the future, allowing a fully automated processing of sequencing data and routine instant quality check of sequencing runs from desktop sequencers. A web access is available at http://tapir.cbs.dtu.dk. The source code for a python command-line client, a server, and supplementary data are available at http://bit.ly/1aURxkc. PMID:24391826

  19. Low-Bandwidth and Non-Compute Intensive Remote Identification of Microbes from Raw Sequencing Reads

    PubMed Central

    Gautier, Laurent; Lund, Ole

    2013-01-01

    Cheap DNA sequencing may soon become routine not only for human genomes but also for practically anything requiring the identification of living organisms from their DNA: tracking of infectious agents, control of food products, bioreactors, or environmental samples. We propose a novel general approach to the analysis of sequencing data where a reference genome does not have to be specified. Using a distributed architecture we are able to query a remote server for hints about what the reference might be, transferring a relatively small amount of data. Our system consists of a server with known reference DNA indexed, and a client with raw sequencing reads. The client sends a sample of unidentified reads, and in return receives a list of matching references. Sequences for the references can be retrieved and used for exhaustive computation on the reads, such as alignment. To demonstrate this approach we have implemented a web server, indexing tens of thousands of publicly available genomes and genomic regions from various organisms and returning lists of matching hits from query sequencing reads. We have also implemented two clients: one running in a web browser, and one as a python script. Both are able to handle a large number of sequencing reads and from portable devices (the browser-based running on a tablet), perform its task within seconds, and consume an amount of bandwidth compatible with mobile broadband networks. Such client-server approaches could develop in the future, allowing a fully automated processing of sequencing data and routine instant quality check of sequencing runs from desktop sequencers. A web access is available at http://tapir.cbs.dtu.dk. The source code for a python command-line client, a server, and supplementary data are available at http://bit.ly/1aURxkc. PMID:24391826

  20. Novel high-gain, improved-bandwidth, finned-ladder V-band Traveling-Wave Tube slow-wave circuit design

    NASA Technical Reports Server (NTRS)

    Kory, Carol L.; Wilson, Jeffrey D.

    1994-01-01

    The V-band frequency range of 59-64 GHz is a region of the millimeter-wave spectrum that has been designated for inter-satellite communications. As a first effort to develop a high-efficiency V-band Traveling-Wave Tube (TWT), variations on a ring-plane slow-wave circuit were computationally investigated to develop an alternative to the more conventional ferruled coupled-cavity circuit. The ring-plane circuit was chosen because of its high interaction impedance, large beam aperture, and excellent thermal dissipation properties. Despite these advantages, however, low bandwidth and high voltage requirements have, until now, prevented its acceptance outside the laboratory. In this paper, the three-dimensional electrodynamic simulation code MAFIA (solution of MAxwell's Equation by the Finite-Integration-Algorithm) is used to investigate methods of increasing the bandwidth and lowering the operating voltage of the ring-plane circuit. Calculations of frequency-phase dispersion, beam on-axis interaction impedance, attenuation and small-signal gain per wavelength were performed for various geometric variations and loading distributions of the ring-plane TWT slow-wave circuit. Based on the results of the variations, a circuit termed the finned-ladder TWT slow-wave circuit was designed and is compared here to the scaled prototype ring-plane and a conventional ferruled coupled-cavity TWT circuit over the V-band frequency range. The simulation results indicate that this circuit has a much higher gain, significantly wider bandwidth, and a much lower voltage requirement than the scaled ring-plane prototype circuit, while retaining its excellent thermal dissipation properties. The finned-ladder circuit has a much larger small-signal gain per wavelength than the ferruled coupled-cavity circuit, but with a moderate sacrifice in bandwidth.

  1. A heuristic to bandwidth allocation and sales limit setting for Internet service providers

    NASA Astrophysics Data System (ADS)

    You, Peng Sheng; Hsieh, Yi-Chih; Ikuta, Seizo

    2012-11-01

    When requesting on-line, many subscribers have experienced the situation in which their on-line requests are denied or their connection speeds are far below their contracted speed limits. This bad customer experience may result from the situation in which Internet service providers (ISPs) accept customers' subscriptions without setting sales limits. As subscribers are potential on-line users, controlling the number of subscribers can be considered as an approach to overcome this problem. The goal of this article is to develop decisions to maximise revenues of ISPs while guaranteeing the expected service quality for distinct service classes. The developed model was a resource constrained nonlinear integer problem, and a heuristic approach was provided to acquire a near-optimal solution. Limited numerical results showed that the proposed heuristic approach can solve this problem efficiently.

  2. Holographic display system for dynamic synthesis of 3D light fields with increased space bandwidth product.

    PubMed

    Agour, Mostafa; Falldorf, Claas; Bergmann, Ralf B

    2016-06-27

    We present a new method for the generation of a dynamic wave field with high space bandwidth product (SBP). The dynamic wave field is generated from several wave fields diffracted by a display which comprises multiple spatial light modulators (SLMs) each having a comparably low SBP. In contrast to similar approaches in stereoscopy, we describe how the independently generated wave fields can be coherently superposed. A major benefit of the scheme is that the display system may be extended to provide an even larger display. A compact experimental configuration which is composed of four phase-only SLMs to realize the coherent combination of independent wave fields is presented. Effects of important technical parameters of the display system on the wave field generated across the observation plane are investigated. These effects include, e.g., the tilt of the individual SLM and the gap between the active areas of multiple SLMs. As an example of application, holographic reconstruction of a 3D object with parallax effects is demonstrated. PMID:27410593

  3. Stochastic excitation and Hadamard correlation spectroscopy with bandwidth extension in RF FT-EPR

    PubMed Central

    Pursley, Randall H.; Kakareka, John; Salem, Ghadi; Devasahayam, Nallathamby; Subramanian, Sankaran; Tschudin, Rolf G.; Krishna, Murali C.; Pohida, Thomas J.

    2012-01-01

    The application of correlation spectroscopy employing stochastic excitation and the Hadamard transform to time-domain Fourier transform electron paramagnetic resonance (FT-EPR) spectroscopy in the radiofrequency (RF) band is described. An existing, time-domain FT-EPR spectrometer system with a Larmor frequency (Lf) of 300 MHz was used to develop this technique by incorporating a pseudo-random pulse sequence generator to output the maximum length binary sequence (MLBS, 10- and 11-bit). Software developed to control the EPR system setup, acquire the signals, and post process the data, is outlined. The software incorporates the Hadamard transform algorithm to perform the required cross-correlation of the acquired signal and the MLBS after stochastic excitation. To accommodate the EPR signals, bandwidth extension was accomplished by sampling at a rate many times faster than the RF pulse repetition rate, and subsequent digital signal processing of the data. The results of these experiments showed that there was a decrease in the total acquisition time, and an improved free induction decay (FID) signal-to-noise (S/N) ratio compared to the conventional coherent averaging approach. These techniques have the potential to reduce the RF pulse power to the levels used in continuous wave (CW) EPR while retaining the advantage of time-domain EPR methods. These methods have the potential to facilitate the progression to in vivo FT-EPR imaging of larger volumes. PMID:12762981

  4. Ultra-wide Bandwidth Inter-Chip Interconnects for Heterogeneous Millimeter-Wave and THz Circuits

    NASA Astrophysics Data System (ADS)

    Fay, Patrick; Bernstein, Gary H.; Lu, Tian; Kulick, Jason M.

    2016-09-01

    Heterogeneous chip-to-chip interconnects with low loss and ultra-wide bandwidths have been demonstrated. Coplanar waveguide-based interconnects between GaAs and Si die have been fabricated and characterized and the results compared to expectations from full-wave electromagnetic simulation. Broadband transmission characteristics were obtained, with insertion losses below 0.3 dB at 100 GHz and below 0.8 dB at frequencies up to 220 GHz demonstrated experimentally. The measured return loss exceeded 11.5 dB at all frequencies up to 220 GHz. The interconnects offer low latency, with a measured group delay of 0.69 ps. The measured results are in good agreement with full-wave simulations, indicating that the measured results do not suffer from significant impairments compared to theoretical predictions. The demonstrated interconnects offer an alternative to conventional approaches to millimeter-wave circuit and system integration, by enabling the compact realization of circuits in the microwave, millimeter-wave, sub-millimeter-wave, and THz frequency regimes in heterogeneous device technologies with very low chip-to-chip insertion loss.

  5. Adaptive two-stage Karhunen-Loeve-transform scheme for spectral decorrelation in hyperspectral bandwidth compression

    NASA Astrophysics Data System (ADS)

    Saghri, John A.

    2010-05-01

    A computationally efficient adaptive two-stage Karhunen-Loeve transform (KLT) scheme for spectral decorrelation in hyperspectral lossy bandwidth compression is presented. The component decorrelation of the JPEG 2000 (extension 2) is replaced with an adaptive two-stage KLT scheme. The data are partitioned into small subsets. The spectral correlation within each partition is removed via a first-stage KLT. The interpartition spectral correlation is removed using a second-stage KLT applied to the resulting top few sets of equilevel principal component (PC) images. Since only a fraction of each equilevel first-stage PC images are used in the second stage, the KLT transformation matrices will have smaller sizes, leading to further improvement in computational complexity and coding efficiency. The computation of the proposed approach is parametrically quantified. It is shown that reconstructed image quality, as measured via statistical and/or machine-based exploitation measures, is improved by using a smaller partition size in the first-stage KLT. A criterion based on the components of the eigenvectors of the cross-covariance matrix is established to select first-stage PC images, which are used in the second-stage KLT. The proposed scheme also reduces the overhead bits required to transmit the covariance information to the receiver in conjunction with the coding bitstream.

  6. VCSEL arrays for high-aggregate bandwidth of up to 1.34 Tbps

    NASA Astrophysics Data System (ADS)

    Grabherr, Martin; Intemann, Steffan; King, Roger; Wabra, Stefan; Jäger, Roland; Riedl, Michael

    2014-02-01

    Even though the lane speed of VCSEL based AOC and transceivers has reached 25 Gbps and beyond [1-7], parallel optics are getting even more important in order to meet the increasing demand for aggregate bandwidths in upcoming applications, among others, 100 Gigabit Ethernet, Infiniband EDR, or EOM (embedded optical modules). As 100 Gbps can be achieved by, e.g., 4 times 25 Gbps using standard QSFP form factor, different approaches are using large scale 2D VCSEL arrays operating at lower lane speeds. Early work on 2D VCSEL based transceivers has already been presented beginning of this century [8] and recent work also addressed the potential of this technology [9,10]. In 2013, Compass EOS has introduced a 1.34 Tbps core router solution [11,12,13] that incorporates 2D VCSEL arrays of 14x12 emitters designed and manufactured by Philips U-L-M Photonics. The VCSEL array is mounted face down onto a CMOS ASIC, directly on top of the analog area. The emission wavelength of 1000 nm allows for substrate side emission and thus for flip-chip mounting as well as the possibility of integrating 2D microlens arrays onto the stack of CMOS and VCSEL array. After briefly introducing the router with regard to the incorporated VCSEL technology we discuss the design and performance of the VCSEL array. Finally, the assembly solution for this most compact and dense transceiver solution is presented.

  7. BASALT 1: Extravehicular Activity Science Operations Concepts under Communication Latency and Bandwidth Constraints at Craters of the Moon, Idaho

    NASA Technical Reports Server (NTRS)

    Chappell, Steven P.; Beaton, Kara; Miller, Matthew J.; Lim, Darlene S. S.; Abercromby, Andrew F. J.

    2017-01-01

    An over-arching goal of the multi-year Biologic Analog Science Associated with Lava Terrains (BASALT) project is to iteratively develop, implement, and evaluate concepts of operations (ConOps) and supporting capabilities intended to enable and enhance human exploration of Mars. Geological and biological scientific fieldwork is being conducted during four total deployments at two high-fidelity Mars analogs, all within simulated Mars mission conditions that are based on current architectural assumptions for Mars exploration missions. Specific capabilities being evaluated include the use of mobile science platforms, extravehicular informatics, communication and navigation packages, advanced science mission planning tools, and scientifically-relevant instrument packages to achieve the project goals. This paper describes the planning, execution, and results of the first field deployment, referred to as BASALT 1, which consisted of a series of 12 simulated extravehicular activities (EVAs) on the lava terrains of Craters of the Moon, Idaho. Scientific objectives of the EVAs related to determination of how microbial communities and habitability correlate with the physical and geochemical characteristics of chemically-altered basalt environments. The concept of operations (ConOps) and capabilities deployed and tested during BASALT 1 were based on extensive data from previous NASA trade studies and analog testing, and the primary research question was whether those ConOps and capabilities would work acceptably when performing real (non-simulated) biological and geological scientific exploration under four different communication scenarios. Specifically, communication latencies of 5 and 15 minutes one-way light time (OWLT) were tested; these delays fall within the range of 4 to 22 minute OWLT delays that would be experienced during a Mars mission. Science operations were also conducted under low bandwidth conditions (0.512 Mb/s uplink, 1.54 Mb/s downlink), representing a

  8. Expanding the Bandwidth of Slow and Fast Pulse Propagation in Coupled Micro-resonators

    NASA Technical Reports Server (NTRS)

    Smith, David D.; Chang, Hongrok

    2007-01-01

    Coupled resonators exhibit coherence effects which can be exploited for the delay or advancement of pulses with minimal distortion. The bandwidth and normalized pulse delay are simultaneously enhanced by proper choice of the inter-resonator couplings.

  9. A High Performance and Low Bandwidth Multi-Standard Motion Compensation Design for HD Video Decoder

    NASA Astrophysics Data System (ADS)

    Chen, Xianmin; Liu, Peilin; Zhou, Dajiang; Zhu, Jiayi; Pan, Xingguang; Goto, Satoshi

    Motion compensation is widely used in many video coding standards. Due to its bandwidth requirement and complexity, motion compensation is one of the most challenging parts in the design of high definition video decoder. In this paper, we propose a high performance and low bandwidth motion compensation design, which supports H.264/AVC, MPEG-1/2 and Chinese AVS standards. We introduce a 2-Dimensional cache that can greatly reduce the external bandwidth requirement. Similarities among the 3 standards are also explored to reduce hardware cost. We also propose a block-pipelining strategy to conceal the long latency of external memory access. Experimental results show that our motion compensation design can reduce the bandwidth by 74% in average and it can real-time decode 1920x1088@30fps video stream at 80MHz.

  10. Stimulated Brillouin scattering gain bandwidth reduction and applications in microwave photonics and optical signal processing

    NASA Astrophysics Data System (ADS)

    Preussler, Stefan; Schneider, Thomas

    2016-03-01

    Stimulated Brillouin scattering (SBS) is one of the most dominant nonlinear effects in standard single-mode fibers and its unique spectral characteristics, especially the narrow bandwidth, enable many different applications. Most of the applications would benefit from a narrower bandwidth. Different methods for the bandwidth reduction of SBS in optical fibers are presented and discussed. A bandwidth reduction down to 17% of the natural gain can be achieved by the superposition of the gain with two losses or the utilization of a multistage system. Furthermore, applications in the field of microwave photonics and optical signal processing like high-resolution spectroscopy of communication signals, the storage of optical data packets as well as the processing of frequency combs including generation of millimeter waves and ideal sinc-shaped Nyquist pulses are presented.

  11. Tuning gain and bandwidth of traveling wave tubes using metamaterial beam-wave interaction structures

    SciTech Connect

    Lipton, Robert Polizzi, Anthony

    2014-10-14

    We employ metamaterial beam-wave interaction structures for tuning the gain and bandwidth of short traveling wave tubes. The interaction structures are made from metal rings of uniform cross section, which are periodically deployed along the length of the traveling wave tube. The aspect ratio of the ring cross sections is adjusted to control both gain and bandwidth. The frequency of operation is controlled by the filling fraction of the ring cross section with respect to the size of the period cell.

  12. Role of Bandwidth in Computation of NDVI From Landsat TM and NOAA AVHRR Bands

    NASA Astrophysics Data System (ADS)

    Gupta, R. K.; Vijayan, D.; Prasad, T. S.; Tirumaladevi, N. Ch.

    The observations for wheat, onion, potato and chickpea over the Crop Growth Cycle (CGC) in 3 nm bandwidth were converted to AVHRR and TM bands in visible/red and near-IR spectral regions. Correlation between TM and AVHRR NDVI were very high for all these crops. The additional 0.725-0.76 μm bandwidth in AVHRR as compared to TM was causing reduction in NDVI values for AVHRR when crop NDVI value was more than 0.46

  13. Comparison of steering angle and bandwidth for various phased array antenna concepts

    NASA Astrophysics Data System (ADS)

    Bonjour, Romain; Singleton, Matthew; Leuchtmann, Pascal; Leuthold, Juerg

    2016-08-01

    In this paper we compare different integratable ultra-fast tunable true-time delay concepts with respect to their performances in a phased array system. The performances of the schemes are assessed with respect to the supported range, i.e. the range within which beam steering for a given fractional bandwidth can be achieved with a gain flatness better than 3 dB. We also compare the array gain as of function of steering angle and fractional bandwidth.

  14. Using the Sirocco File System for high-bandwidth checkpoints.

    SciTech Connect

    Klundt, Ruth Ann; Curry, Matthew L.; Ward, H. Lee

    2012-02-01

    The Sirocco File System, a file system for exascale under active development, is designed to allow the storage software to maximize quality of service through increased flexibility and local decision-making. By allowing the storage system to manage a range of storage targets that have varying speeds and capacities, the system can increase the speed and surety of storage to the application. We instrument CTH to use a group of RAM-based Sirocco storage servers allocated within the job as a high-performance storage tier to accept checkpoints, allowing computation to potentially continue asynchronously of checkpoint migration to slower, more permanent storage. The result is a 10-60x speedup in constructing and moving checkpoint data from the compute nodes. This demonstration of early Sirocco functionality shows a significant benefit for a real I/O workload, checkpointing, in a real application, CTH. By running Sirocco storage servers within a job as RAM-only stores, CTH was able to store checkpoints 10-60x faster than storing to PanFS, allowing the job to continue computing sooner. While this prototype did not include automatic data migration, the checkpoint was available to be pushed or pulled to disk-based storage as needed after the compute nodes continued computing. Future developments include the ability to dynamically spawn Sirocco nodes to absorb checkpoints, expanding this mechanism to other fast tiers of storage like flash memory, and sharing of dynamic Sirocco nodes between multiple jobs as needed.

  15. Advancing a Complex Systems Approach to Personalized Learning Communities: Bandwidth, Sightlines, and Teacher Generativity

    ERIC Educational Resources Information Center

    Hamilton, Eric

    2015-01-01

    Educational technologies have advanced one of the most important visions of educational reformers, to customize formal and informal learning to individuals. The application of a complex systems framework to the design of learning ecologies suggests that each of a series of ten desirable and malleable features stimulates or propels the other ten,…

  16. Wide bandwidth chaotic signal generation in a monolithically integrated semiconductor laser via optical injection

    NASA Astrophysics Data System (ADS)

    Yin, Xue-Mei; Zhong, Zhu-Qiang; Zhao, Ling-Juan; Lu, Dan; Qiu, Hai-Ying; Xia, Guang-Qiong; Wu, Zheng-Mao

    2015-11-01

    Wide bandwidth chaotic signal generation in a three-section monolithically integrated semiconductor laser (MISL) under external optical injection is investigated experimentally. Through evaluating the effective bandwidth of chaotic signals, the influences of the optical injection on the bandwidth of chaotic signal from the MISL are analyzed. The experimental results indicate that, for the currents of the DFB section (IDFB) and the phase section (IP) are fixed at 70.00 mA and 34.00 mA, respectively, the effective bandwidth of chaos signal generated by the solitary MISL reaches its maximum value of 14.36 GHz when the current of the amplification section (IA) takes 23.22 mA. After an external optical injection is introduced into the MISL, the effective bandwidth of the generated chaotic signal can be beyond 2.5 times of the maximum value. Furthermore, the effects of the injection strength and the frequency detuning on the effective bandwidth of the generated chaotic signal are also discussed.

  17. Experimental studies of bandwidth and power production in a three-cavity, 35 GHz gyroklystron amplifier

    NASA Astrophysics Data System (ADS)

    Calame, J. P.; Garven, M.; Choi, J. J.; Nguyen, K.; Wood, F.; Blank, M.; Danly, B. G.; Levush, B.

    1999-01-01

    The operating characteristics of a three-cavity, Ka-Band gyroklystron employing a large amount of stagger-tuning are reported. Particular attention is given to examining how the frequency response (peak power, bandwidth, and overall shape) is altered by changes in operating parameters. A peak power of 225 kW at 34.90 GHz, with a 2 μs pulse length, 32% efficiency, 30.3 dB saturated gain, and a 3 dB bandwidth of 0.82% (286 MHz) was obtained with a 70.2 kV, 10.0 A beam at a magnetic field of 13.07 kG. This operating point represents a compromise between the output power and the bandwidth. The operating magnetic field was found to have a dramatic influence on the power-bandwidth tradeoff; a lower field of 12.91 kG produced 245 kW with 0.63% bandwidth, while a higher field of 13.39 kG increased the bandwidth to 0.94% at a lower power of 200 kW. The results are in excellent agreement with large signal simulations.

  18. Accounting for filter bandwidth improves the quantitative accuracy of bioluminescence tomography

    NASA Astrophysics Data System (ADS)

    Taylor, Shelley L.; Mason, Suzannah K. G.; Glinton, Sophie L.; Cobbold, Mark; Dehghani, Hamid

    2015-09-01

    Bioluminescence imaging is a noninvasive technique whereby surface weighted images of luminescent probes within animals are used to characterize cell count and function. Traditionally, data are collected over the entire emission spectrum of the source using no filters and are used to evaluate cell count/function over the entire spectrum. Alternatively, multispectral data over several wavelengths can be incorporated to perform tomographic reconstruction of source location and intensity. However, bandpass filters used for multispectral data acquisition have a specific bandwidth, which is ignored in the reconstruction. In this work, ignoring the bandwidth is shown to introduce a dependence of the recovered source intensity on the bandwidth of the filters. A method of accounting for the bandwidth of filters used during multispectral data acquisition is presented and its efficacy in increasing the quantitative accuracy of bioluminescence tomography is demonstrated through simulation and experiment. It is demonstrated that while using filters with a large bandwidth can dramatically decrease the data acquisition time, if not accounted for, errors of up to 200% in quantitative accuracy are introduced in two-dimensional planar imaging, even after normalization. For tomographic imaging, the use of this method to account for filter bandwidth dramatically improves the quantitative accuracy.

  19. On bandwidth characteristics of tuning fork micro-gyroscope with mechanically coupled sense mode.

    PubMed

    Ni, Yunfang; Li, Hongsheng; Huang, Libin; Ding, Xukai; Wang, Haipeng

    2014-01-01

    The bandwidth characteristics of a tuning fork micro-gyroscope with mechanically coupled sense mode were investigated in this paper to provide some references for mechanical bandwidth design. The concept of sense mode mechanical coupling is introduced first. Theoretical frequency response analyses were then carried out on the mechanical part of the gyroscope. Equations representing the relationships between the differential output signal and the frequency of the input angular rate were deduced in full frequency range and further simplified in low frequency range. Based on these equations, bandwidth characteristics under ideal and non-ideal conditions are discussed. Analytical results show that under ideal conditions, the bandwidth characteristics of a tuning fork micro-gyroscope are similar to those of a single mass micro-gyroscope, but under non-ideal conditions, especially when sense mass and/or stiffness are asymmetric, the bandwidth characteristics would be quite different because the in-phase mode would participate in the anti-phase vibration response. Experimental verifications were carried out on two micro-gyroscope prototypes designed in our laboratory. The deduced equations and analytical results can be used in guiding the mechanical bandwidth design of tuning fork micro-gyroscopes with mechanically coupled sense mode. PMID:25051030

  20. Design and experiment of a LQ controller used in high-bandwidth fast-steering mirror system

    NASA Astrophysics Data System (ADS)

    Xie, Mujun; Ma, Jiaguang; Fu, Chengyu

    2000-07-01

    Space-based laser communication (LASERCOM) requires precision tracking and pointing in the microradian range. However, the angular vibrations of a satellite platform may be of the magnitude of milliradian and the frequency of 100 Hz or higher. For rejection of the platform vibrations there are two ways: line-of-sight stabilization technology or a fine steering mirror (control system with high closed-loop bandwidth. The former is much more complex in structure and difficult in implement than the latter. So, the latter is always adopted in actual space optical communication engineering. This paper describes a linear quadratic (LQ) optimal controller based on modern control theory for FSM system. Compared with classical controller, the proposed LQ has several advantages: (1) the LQ controller widens the system's closed loop bandwidth; (2) the large improvement in the system dynamic performance; (3) the significant improvement of the system rejection capability on high frequencies disturbance. The FSM system with the LQ controller have been designed and tested. The results confirm the advantages of the LQ controller above and show that it is an efficient control approach for FSM system in LASERCOM.

  1. A novel ±0.8 V high-performance voltage-tunable CDTA with enhanced bandwidth

    NASA Astrophysics Data System (ADS)

    Xia, Zanming; Wang, Chunhua; Kuang, Jun; Jin, Jie

    2016-04-01

    In this article, we propose a novel high-performance complementary metal oxide semiconductor (CMOS) current differencing transconductance amplifier (CDTA) with a transconductance gain (GM) that can be linearly tuned by a voltage. By using a high-speed, low-voltage, cascaded current mirror active resistance compensation technique, the proposed CDTA circuit exhibits wide frequency bandwidths, high current tracking precisions as well as large output impedances. The linear-tunable GM of the CDTA is designed with the use of linear composite metal oxide semiconductor field-effect transistor as basic cells in the circuit. Combining these two approaches, several design concerns are studied, including: impedance characteristic, tracking errors, offset and linearity and noise. The prototype chip with a 0.25 mm2 area is fabricated in a GlobalFoundries'0.18 μm CMOS process. The simulated results and measured results with ±0.8 V DC supply voltages are presented, and show extremely wide bandwidths and wide linear tuning range. In addition, a fully differential band-pass filter for a high-speed system is also given as an example to confirm the high performance of the proposed circuit.

  2. Defining acceptable conditions in wilderness

    NASA Astrophysics Data System (ADS)

    Roggenbuck, J. W.; Williams, D. R.; Watson, A. E.

    1993-03-01

    The limits of acceptable change (LAC) planning framework recognizes that forest managers must decide what indicators of wilderness conditions best represent resource naturalness and high-quality visitor experiences and how much change from the pristine is acceptable for each indicator. Visitor opinions on the aspects of the wilderness that have great impact on their experience can provide valuable input to selection of indicators. Cohutta, Georgia; Caney Creek, Arkansas; Upland Island, Texas; and Rattlesnake, Montana, wilderness visitors have high shared agreement that littering and damage to trees in campsites, noise, and seeing wildlife are very important influences on wilderness experiences. Camping within sight or sound of other people influences experience quality more than do encounters on the trails. Visitors’ standards of acceptable conditions within wilderness vary considerably, suggesting a potential need to manage different zones within wilderness for different clientele groups and experiences. Standards across wildernesses, however, are remarkably similar.

  3. From requirements to acceptance tests

    NASA Technical Reports Server (NTRS)

    Baize, Lionel; Pasquier, Helene

    1993-01-01

    From user requirements definition to accepted software system, the software project management wants to be sure that the system will meet the requirements. For the development of a telecommunication satellites Control Centre, C.N.E.S. has used new rules to make the use of tracing matrix easier. From Requirements to Acceptance Tests, each item of a document must have an identifier. A unique matrix traces the system and allows the tracking of the consequences of a change in the requirements. A tool has been developed, to import documents into a relational data base. Each record of the data base corresponds to an item of a document, the access key is the item identifier. Tracing matrix is also processed, providing automatically links between the different documents. It enables the reading on the same screen of traced items. For example one can read simultaneously the User Requirements items, the corresponding Software Requirements items and the Acceptance Tests.

  4. Sampling Theorem in Terms of the Bandwidth and Sampling Interval

    NASA Technical Reports Server (NTRS)

    Dean, Bruce H.

    2011-01-01

    An approach has been developed for interpolating non-uniformly sampled data, with applications in signal and image reconstruction. This innovation generalizes the Whittaker-Shannon sampling theorem by emphasizing two assumptions explicitly (definition of a band-limited function and construction by periodic extension). The Whittaker- Shannon sampling theorem is thus expressed in terms of two fundamental length scales that are derived from these assumptions. The result is more general than what is usually reported, and contains the Whittaker- Shannon form as a special case corresponding to Nyquist-sampled data. The approach also shows that the preferred basis set for interpolation is found by varying the frequency component of the basis functions in an optimal way.

  5. The MAGNEX large acceptance spectrometer

    SciTech Connect

    Cavallaro, M.; Cappuzzello, F.; Cunsolo, A.; Carbone, D.; Foti, A.

    2010-03-01

    The main features of the MAGNEX large acceptance magnetic spectrometer are described. It has a quadrupole + dipole layout and a hybrid detector located at the focal plane. The aberrations due to the large angular (50 msr) and momentum (+- 13%) acceptance are reduced by an accurate hardware design and then compensated by an innovative software ray-reconstruction technique. The obtained resolution in energy, angle and mass are presented in the paper. MAGNEX has been used up to now for different experiments in nuclear physics and astrophysics confirming to be a multipurpose device.

  6. Masked threshold for noise bands masked by narrower bands of noise: Effects of masker bandwidth and center frequency.

    PubMed

    Taghipour, Armin; Moore, Brian C J; Edler, Bernd

    2016-05-01

    This paper examines how masked thresholds depend on the masker bandwidth and center frequency when the masker has a smaller bandwidth than the signal. The signal bandwidth was equal to the equivalent rectangular bandwidth of the auditory filter and the masker bandwidth was 0.1, 0.35, or 0.6 times the signal bandwidth. The masker and signal were centered at the same frequency of 257, 697, 1538, 3142, or 6930 Hz. Masked thresholds were estimated using a two-interval two-alternative forced-choice paradigm and a three-down one-up adaptive staircase method. Masked thresholds increased with increasing masker bandwidth and were lowest for medium center frequencies. PMID:27250136

  7. A new theoretical basis for the bandwidth method and optimal power ratios for the damping estimation

    NASA Astrophysics Data System (ADS)

    Yin, H. P.

    2008-11-01

    Using the well-known bandwidth formula and the half power bandwidth formula [R.E.D. Bishop, G.M.L. Gladwell, An investigation into the theory of resonance testing, Philosophical Transactions of the Royal Society of London A 255 (1963) 241-280], in particular, is the simplest way to estimate modal damping for engineers. By using the half power bandwidth formula, the damping factor is estimated to be approximately the half bandwidth at the half power points. One of the major limitations that restrict the use of this method is the coupling effect between closely spaced modes. In this paper, the dependence of the damping estimation accuracy on the selected power ratios is studied with both analytical and experimental data of frequency response functions. The results show that by selecting adequate power ratio values, the coupling effect can be minimized and the estimation accuracy can be significantly improved for closely spaced modes. A further improvement of accuracy can be obtained by applying the algorithm of mode isolation [H.P. Yin, D. Duhamel, Substraction technique and finite difference formulas for modal parameter estimation, Mechanical Systems and Signal Processing 18 (2004) 1497-1503; M.S. Allen, J.H. Ginsberg, A global, single-input-multi-output (SIMO) implementation of the algorithm of mode isolation and application to analytical and experimental data, Mechanical Systems and Signal Processing 20 (2006) 1090-1111]. Also an exact bandwidth formula in case of a single degree of freedom system is presented and the link between the exact formula and the classical approximated formula is indicated. The exact bandwidth formula provides a new theoretical basis of the bandwidth method for the damping estimation from frequency response functions.

  8. Statistical results describing the bandwidth and coherence coefficient of whistler mode waves using THEMIS waveform data

    NASA Astrophysics Data System (ADS)

    Gao, X.; Li, W.; Thorne, R. M.; Bortnik, J.; Angelopoulos, V.; Lu, Q.; Tao, X.; Wang, S.

    2014-11-01

    The bandwidths and coherence coefficients of lower band whistler mode waves are analyzed using Time History of Events and Macroscale Interactions during Substorms (THEMIS) waveform data for rising tones, falling tones, and hiss-like emissions separately. We also evaluate their dependences on the spatial location, electron density, the ratio of plasma frequency to local electron gyrofrequency (fpe/fce), and the wave amplitude. Our results show that the bandwidth normalized by the local electron gyrofrequency (fce) of rising and falling tones is very narrow (~0.01 fce), smaller than that of the hiss-like emissions (~0.025 fce). Meanwhile, the normalized bandwidth of discrete emissions gradually decreases with increasing wave amplitude, whereas that of hiss-like emissions increases slowly. The coherence coefficient of rising and falling tones is extremely large (~1), while the coherence coefficient of hiss-like emissions is smaller but is still larger than 0.5. For all categories of whistler mode waves, the normalized bandwidth increases at larger L shells. Furthermore, the normalized bandwidth is positively correlated with local fpe/fce but is inversely correlated with the electron density. Interactions between radiation belt electrons and whistler mode waves have been widely described by quasi-linear diffusion theory. Our results suggest that although quasi-linear theory is not entirely applicable for modeling electron interactions with rising and falling tones due to their narrow bandwidth and high coherence coefficient, it is suitable to treat wave-particle interactions between electrons and low-amplitude hiss-like emissions. Moreover, the correlations between the normalized bandwidth of chorus waves (especially the discrete emissions) and other parameters may provide insights for the generation mechanism of chorus waves.

  9. An impact excitation system for repeatable, high-bandwidth modal testing of miniature structures

    NASA Astrophysics Data System (ADS)

    Bediz, Bekir; Korkmaz, Emrullah; Burak Ozdoganlar, O.

    2014-06-01

    Miniature components and devices are increasingly seen in a myriad of applications. In general, the dynamic behavior of miniature devices is critical to their functionality and performance. However, modal testing of miniature structures poses many challenges. This paper presents a design and evaluation of an impact excitation system (IES) for repeatable, high-bandwidth, controlled-force modal testing of miniature structures. Furthermore, a dynamic model of the system is derived and experimentally validated to enable the identification of the system parameters that yield single-hit impacts with desired bandwidth and force magnitude. The system includes a small instrumented impact tip attached to a custom designed flexure-based body, an automated electromagnetic release mechanism, and various precision positioners. The excitation bandwidth and the impact force magnitude can be controlled by selecting the system parameters. The dynamic model of the system includes the structural dynamics of the flexure-based body, the electromagnetic force and the associated eddy-current damping, and the impact event. A validation study showed an excellent match between the model simulations and experiments in terms of impact force and bandwidth. The model is then used to create process maps that relate the system parameters to the number of hits (single vs. multiple), the impact force magnitudes and the excitation bandwidths. These process maps can be used to select system parameters or predict system response for a given set of parameters. A set of experiments is conducted to compare the performances of the IES and a (manual) miniature impact hammer. It is concluded that the IES significantly improves repeatability in terms of the impact bandwidth, location, and force magnitude, while providing a high excitation-bandwidth and excellent coherence values. The application of the IES is demonstrated through modal testing of a miniature contact-probe system.

  10. Nitrogen trailer acceptance test report

    SciTech Connect

    Kostelnik, A.J.

    1996-02-12

    This Acceptance Test Report documents compliance with the requirements of specification WHC-S-0249. The equipment was tested according to WHC-SD-WM-ATP-108 Rev.0. The equipment being tested is a portable contained nitrogen supply. The test was conducted at Norco`s facility.

  11. Helping Our Children Accept Themselves.

    ERIC Educational Resources Information Center

    Gamble, Mae

    1984-01-01

    Parents of a child with muscular dystrophy recount their reactions to learning of the diagnosis, their gradual acceptance, and their son's resistance, which was gradually lessened when he was provided with more information and treated more normally as a member of the family. (CL)

  12. Acceptability of Treatments for Plagiarism

    ERIC Educational Resources Information Center

    Carter, Stacy L.; Punyanunt-Carter, Narissra Maria

    2007-01-01

    This study focused on various treatments for addressing incidents of plagiarism by college students. College students rated the acceptability of different responses by college faculty to a case description of a college student who engaged in plagiarism. The findings revealed that students found some methods of addressing this problem behavior by…

  13. Euthanasia Acceptance: An Attitudinal Inquiry.

    ERIC Educational Resources Information Center

    Klopfer, Fredrick J.; Price, William F.

    The study presented was conducted to examine potential relationships between attitudes regarding the dying process, including acceptance of euthanasia, and other attitudinal or demographic attributes. The data of the survey was comprised of responses given by 331 respondents to a door-to-door interview. Results are discussed in terms of preferred…

  14. IWGT report on quantitative approaches to genotoxicity risk assessment II. Use of point-of-departure (PoD) metrics in defining acceptable exposure limits and assessing human risk

    EPA Science Inventory

    This is the second of two reports from the International Workshops on Genotoxicity Testing (IWGT) Working Group on Quantitative Approaches to Genetic Toxicology Risk Assessment (the QWG). The first report summarized the discussions and recommendations of the QWG related to the ne...

  15. Relaxor-PT single crystals for broad bandwidth, high power sonar projectors

    NASA Astrophysics Data System (ADS)

    Sherlock, Nevin P.

    2010-06-01

    showed twice the dynamic strain of unmodified PMNT as a function of electric field, and in many cases also showed greater maximum strain at failure (0.3% compared to 0.15% for unmodified PMNT). When QM was measured as a function of drive level, it was shown to sharply decrease under high dynamic strain. Modified single crystals with greater small signal QM values than unmodified PMNT maintain higher QM values under high drive, with Q M = 50--150 immediately prior to sample failure (Q M = 20 for base PMNT immediately prior to failure). The temperature dependence of modified PMNT single crystal electromechanical properties was also determined, and it was shown that modified crystals possess greater property stability than unmodified PMNT. While the base composition shows a limiting rhombohedral-tetragonal transition at 95 °C, modified single crystals using ternary PIN and PZT components show increased transition temperatures of 125 °C and 144 °C, respectively. The greater phase stability of the PIN ternary crystal was also examined through the coercive field, which was shown to be much greater than that of unmodified PMNT over the temperature range of interest (Ec = 5 kV/cm and 2 kV/cm, respectively, at room temperature). From the combined set of property measurements, the heat generation of each material was predicted for an arbitrary projector device. As a consequence of the lower losses, modified single crystals showed as little as 25% of the heat generation value for unmodified PMNT single crystals. Using this prediction as a performance metric, the crystals with the lowest heat generation were selected for device testing. Transducers with base PMNT and modified single crystals were designed using a finite element modeling approach. This model predicted approximately two octaves of bandwidth for the transducer geometry under investigation. A 5 dB decrease in acoustic output was observed when moving from base PMNT to highly modified crystals, but that result does not

  16. Volumetric optoacoustic imaging with multi-bandwidth deconvolution.

    PubMed

    Buehler, Andreas; Deán-Ben, X Luís; Razansky, Daniel; Ntziachristos, Vasilis

    2014-04-01

    Optoacoustic (photoacoustic) imaging based on cylindrically focused 1-D transducer arrays comes with powerful characteristics in visualizing optical contrast. Parallel reading of multiple detectors arranged around a tissue cross section enables capturing data for generating images of this plane within micro-seconds. Dedicated small animals scanners and handheld systems using 1-D cylindrically focused ultrasound transducer arrays have demonstrated real-time cross-sectional imaging and high in-plane resolution. Yet, the resolution achieved along the axis perpendicular to the focal plane, i.e., the elevation resolution, is determined by the focusing capacities of the detector and is typically lower than the in-plane resolution. Herein, we investigated whether deconvolution of the sensitivity field of the transducer could lead to tangible image improvements. We showcase the findings on experimental measurements from phantoms and animals and discuss the features and the limitations of the approach in improving resolution along the elevation dimension. PMID:24058023

  17. Frequency and bandwidth conversion of single photons in a room-temperature diamond quantum memory

    PubMed Central

    Fisher, Kent A. G.; England, Duncan G.; MacLean, Jean-Philippe W.; Bustard, Philip J.; Resch, Kevin J.; Sussman, Benjamin J.

    2016-01-01

    The spectral manipulation of photons is essential for linking components in a quantum network. Large frequency shifts are needed for conversion between optical and telecommunication frequencies, while smaller shifts are useful for frequency-multiplexing quantum systems, in the same way that wavelength division multiplexing is used in classical communications. Here we demonstrate frequency and bandwidth conversion of single photons in a room-temperature diamond quantum memory. Heralded 723.5 nm photons, with 4.1 nm bandwidth, are stored as optical phonons in the diamond via a Raman transition. Upon retrieval from the diamond memory, the spectral shape of the photons is determined by a tunable read pulse through the reverse Raman transition. We report central frequency tunability over 4.2 times the input bandwidth, and bandwidth modulation between 0.5 and 1.9 times the input bandwidth. Our results demonstrate the potential for diamond, and Raman memories in general, as an integrated platform for photon storage and spectral conversion. PMID:27045988

  18. Studies of bandwidth dependence of laser plasma instabilities driven by the Nike laser

    NASA Astrophysics Data System (ADS)

    Weaver, J.; Kehne, D.; Obenschain, S.; Serlin, V.; Schmitt, A. J.; Oh, J.; Lehmberg, R. H.; Brown, C. M.; Seely, J.; Feldman, U.

    2012-10-01

    Experiments at the Nike laser facility of the Naval Research Laboratory are exploring the influence of laser bandwidth on laser plasma instabilities (LPI) driven by a deep ultraviolet pump (248 nm) that incorporates beam smoothing by induced spatial incoherence (ISI). In early ISI studies with longer wavelength Nd:glass lasers (1054 nm and 527 nm),footnotetextObenschain, PRL 62(1989);Mostovych, PRL 62(1987);Peyser, Phys. Fluids B 3(1991). stimulated Raman scattering, stimulated Brillouin scattering, and the two plasmon decay instability were reduced when wide bandwidth ISI (δν/ν˜0.03-0.19%) pulses irradiated targets at moderate to high intensities (10^14-10^15 W/cm^2). The current studies will compare the emission signatures of LPI from planar CH targets during Nike operation at large bandwidth (δν˜1THz) to observations for narrower bandwidth operation (δν˜0.1-0.3THz). These studies will help clarify the relative importance of the short wavelength and wide bandwidth to the increased LPI intensity thresholds observed at Nike. New pulse shapes are being used to generate plasmas with larger electron density scale-lengths that are closer to conditions during pellet implosions for direct drive inertial confinement fusion.

  19. Receiver bandwidth effects on complex modulation and detection using directly modulated lasers.

    PubMed

    Yuan, Feng; Che, Di; Shieh, William

    2016-05-01

    Directly modulated lasers (DMLs) have long been employed for short- and medium-reach optical communications due to their low cost. Recently, a new modulation scheme called complex modulated DMLs has been demonstrated showing a significant optical signal to noise ratio sensitivity enhancement compared with the traditional intensity-only detection scheme. However, chirp-induced optical spectrum broadening is inevitable in complex modulated systems, which may imply a need for high-bandwidth receivers. In this Letter, we study the impact of receiver bandwidth effects on the performance of complex modulation and coherent detection systems based on DMLs. We experimentally demonstrate that such systems exhibit a reasonable tolerance for the reduced receiver bandwidth. For 10 Gbaud 4-level pulse amplitude modulation signals, the required electrical bandwidth is as low as 8.5 and 7.5 GHz for 7% and 20% forward error correction, respectively. Therefore, it is feasible to realize DML-based complex modulated systems using cost-effective receivers with narrow bandwidth. PMID:27128069

  20. Movie approximation technique for the implementation of fast bandwidth-smoothing algorithms

    NASA Astrophysics Data System (ADS)

    Feng, Wu-chi; Lam, Chi C.; Liu, Ming

    1997-12-01

    Bandwidth smoothing algorithms can effectively reduce the network resource requirements for the delivery of compressed video streams. For stored video, a large number of bandwidth smoothing algorithms have been introduced that are optimal under certain constraints but require access to all the frame size data in order to achieve their optimal properties. This constraint, however, can be both resource and computationally expensive, especially for moderately priced set-top-boxes. In this paper, we introduce a movie approximation technique for the representation of the frame sizes of a video, reducing the complexity of the bandwidth smoothing algorithms and the amount of frame data that must be transmitted prior to the start of playback. Our results show that the proposed approximation technique can accurately approximate the frame data with a small number of piece-wise linear segments without affecting the performance measures that the bandwidth soothing algorithms are attempting to achieve by more than 1%. In addition, we show that implementations of this technique can speed up execution times by 100 to 400 times, allowing the bandwidth plan calculation times to be reduced to tens of milliseconds. Evaluation using a compressed full-length motion-JPEG video is provided.

  1. Bandwidth limitation in QPSK optical coherent receiver with DAML carrier phase estimation

    NASA Astrophysics Data System (ADS)

    Chen, Jian; Feng, Tianping; Fan, Yuanwei; Ma, Zhaohui; You, Xiaodi

    2015-08-01

    We study the limitation of electrical bandwidth in QPSK optical coherent receiver with decision-aided maximum likelihood (DAML) carrier phase estimation. Before signal sampling, a low-pass rectangular filter is utilized to model the bandwidth limitation of electronic devices in the receiver. On one hand the limited bandwidth can reduce the power of additive noise, on the other hand it would distort the signal since inter-symbol interference (ISI) between adjacent symbols occurs. In this paper we discuss the effects on signal amplitude and phase caused by ISI and find original distribution of QPSK constellation points will shift due to ISI. When adjacent symbol interference, that is, the ISI effect of one previous symbol, is taken into account, the distribution changes into the form of 16-QAM, while changing as 4K+1-QAM if K previous symbols are considered. The impact on the subsequent DAML algorithm and the final bit error rate (BER) calculation due to constellation points shifts are analyzed intensively. Monte-Carlo (MC) simulation results show that 0.7 to 0.9 times symbol rate is a reasonable bandwidth range for different optical signal to noise ratios (OSNRs), and optimum bandwidth is often inside this range. Results also reveal that filter-induced ISI would degrade the BER performance of DAML receiver when OSNR is over 10 dB.

  2. Frequency and bandwidth conversion of single photons in a room-temperature diamond quantum memory.

    PubMed

    Fisher, Kent A G; England, Duncan G; MacLean, Jean-Philippe W; Bustard, Philip J; Resch, Kevin J; Sussman, Benjamin J

    2016-01-01

    The spectral manipulation of photons is essential for linking components in a quantum network. Large frequency shifts are needed for conversion between optical and telecommunication frequencies, while smaller shifts are useful for frequency-multiplexing quantum systems, in the same way that wavelength division multiplexing is used in classical communications. Here we demonstrate frequency and bandwidth conversion of single photons in a room-temperature diamond quantum memory. Heralded 723.5 nm photons, with 4.1 nm bandwidth, are stored as optical phonons in the diamond via a Raman transition. Upon retrieval from the diamond memory, the spectral shape of the photons is determined by a tunable read pulse through the reverse Raman transition. We report central frequency tunability over 4.2 times the input bandwidth, and bandwidth modulation between 0.5 and 1.9 times the input bandwidth. Our results demonstrate the potential for diamond, and Raman memories in general, as an integrated platform for photon storage and spectral conversion. PMID:27045988

  3. Frequency and bandwidth conversion of single photons in a room-temperature diamond quantum memory

    NASA Astrophysics Data System (ADS)

    Fisher, Kent A. G.; England, Duncan G.; Maclean, Jean-Philippe W.; Bustard, Philip J.; Resch, Kevin J.; Sussman, Benjamin J.

    2016-04-01

    The spectral manipulation of photons is essential for linking components in a quantum network. Large frequency shifts are needed for conversion between optical and telecommunication frequencies, while smaller shifts are useful for frequency-multiplexing quantum systems, in the same way that wavelength division multiplexing is used in classical communications. Here we demonstrate frequency and bandwidth conversion of single photons in a room-temperature diamond quantum memory. Heralded 723.5 nm photons, with 4.1 nm bandwidth, are stored as optical phonons in the diamond via a Raman transition. Upon retrieval from the diamond memory, the spectral shape of the photons is determined by a tunable read pulse through the reverse Raman transition. We report central frequency tunability over 4.2 times the input bandwidth, and bandwidth modulation between 0.5 and 1.9 times the input bandwidth. Our results demonstrate the potential for diamond, and Raman memories in general, as an integrated platform for photon storage and spectral conversion.

  4. SPDC correlated photon source filtered for narrowed bandwidth using volume Bragg grating

    NASA Astrophysics Data System (ADS)

    Slattery, Oliver; Kuo, Paulina; Kim, Yong-Su; Ma, Lijun; Tang, Xiao

    2012-10-01

    A Volume Bragg Grating (VBG) can be used to efficiently extract a narrow bandwidth, highly collimated beam from an otherwise broad spectrum beam. We use a VBG to extract a narrow bandwidth of signal spectrum from a broadband Spontaneous Parametric Down-Conversion source to optimally match the narrow detection bandwidth of our idler upconversion detector. Improved coincidence count rates and visibility can be achieved when limiting signal-spectrum detection to the narrow signal bandwidth whose photons are correlated with a narrow idler-spectrum bandwidth that has been selected by the up-conversion detector. We compare coincidence count rate and visibility for when the entire signal spectrum is detected and when the spectrum has been filtered by the VBG. We further relax the collection techniques and show that following the VBG, the coincidence count rate improves with minimal loss in visibility compared to when the entire spectrum is detected. We introduce our initial efforts at using the VBG to further narrow the signal spectrum by placing it inside a multipass cavity. Additionally, we further adapt the single photon level up-conversion spectrometer, previously developed for idler spectrum measurement, to indirectly measure the single photon level signal spectrum. We verify its capability for several different wavelength and linewidth selections.

  5. Effects of Stimulus Bandwidth on the Imitation of English Fricatives by Normal-Hearing Children

    PubMed Central

    Stelmachowicz, Patricia G.; Nishi, Kanae; Choi, Sangsook; Lewis, Dawna E.; Hoover, Brenda M.; Dierking, Darcia; Lotto, Andrew

    2008-01-01

    Purpose Recent studies from our laboratory have suggested that reduced audibility in the high frequencies (due to the bandwidth of hearing instruments) may play a role in the delays in phonological development often exhibited by children with hearing impairment. The goal of the current study was to extend previous findings on the effect of bandwidth on fricatives/affricates to more complex stimuli. Method Nine fricatives/affricates embedded in 2-syllable nonsense words were filtered at 5 and 10 kHz and presented to normal-hearing 6–7 year olds who repeated words exactly as heard. Responses were recorded for subsequent phonetic and acoustic analyses. Results Significant effects of talker gender and bandwidth were found, with better performance for the male talker and the wider bandwidth condition. In contrast to previous studies, relatively small (5%) mean bandwidth effects were observed for /s/ and /z/ spoken by the female talker. Acoustic analyses of stimuli used in the previous and the current studies failed to explain this discrepancy. Conclusions It appears likely that a combination of factors (i.e., dynamic cues, prior phonotactic knowledge, and perhaps other unidentified cues to fricative identity) may have facilitated the perception of these complex nonsense words in the current study. PMID:18664693

  6. A Wide-Bandwidth, Low-Noise SIS Receiver Design for Millimeter and Submillimeter Wavelengths

    NASA Technical Reports Server (NTRS)

    Sumner, Matthew; Blain, Andrew; Harris, Andrew; Hu, Robert; LeDuc, Henry G.; Miller, David; Rice, Frank; Weinreb, Sander; Zmuidzinas, Jonas

    2004-01-01

    In principle, millimeter and submillimeter heterodyne receivers using state-of-the-art SIS detectors are capable of extremely large instantaneous bandwidths with noise temperatures within a few Kelvin of the quantum limit. We are applying modem design tools, such as 3D electromagnetic simulators and Caltech's SuperMix SIS analysis package, to develop a new generation of waveguide SIS mixers with very broad RF and IF bandwidths. Our initial design consists of a double-sideband mixer targeted for the 180- 300 GHz band that uses a single SIS junction excited by a full bandwidth, fixed-tuned waveguide probe on a silicon substrate. The IF output band, limited by the MMIC low-noise IF preamplifier, is 6-18 GHz, providing an instantaneous RF bandwidth of 24 GHz (double-sideband). The SIS mixer conversion loss is predicted to be no more than 1-2 dB (single-sideband) with mixer noise temperatures across the band within 10 Kelvin of the quantum limit. The single-sideband receiver noise temperature goal is 70 Kelvin. The wide instantaneous bandwidth and low noise will result in an instrument capable of a variety of important astrophysical observations beyond the capabilities of current instruments. Lab testing of the receiver will begin in the summer of 2002, and a demonstration on the CSO should occur in the spring of 2003.

  7. Improvement on Diversity Gain with Filter Bandwidth Enlargement in Fractional Sampling OFDM Receiver

    NASA Astrophysics Data System (ADS)

    Shinkai, Toshiya; Nishimura, Haruki; Sanada, Yukitoshi

    A diversity scheme with Fractional Sampling (FS) in an OFDM receiver has been investigated recently. Through FS, it is possible to separate multipath components and obtain diversity gain in OFDM systems. Enlargement of the bandwidth of the total frequency response between transmit and receive baseband filters allows the FS scheme to achieve path diversity. However, the transmit filter has to be designed according to the spectrum mask of the wireless standards such as IEEE802.11a/g to avoid interference to the other communication systems and the frequency response of the composite channel including the transmit and receive filters has often been set to minimal bandwidth to eliminate adjacent channel signals. In order to achieve the maximum signal-to-noise ratio (SNR), the same filter is commonly used in the transmitter and the receiver. In this paper, the trade-off among the SNR deterioration, adjacent channel interference, and the diversity gain due to the enlargement of the bandwidth of the receive filter is investigated. Numerical results from computer simulations indicate that the BER performance with wider bandwidth in the receiver shows better performance than that with the minimal bandwidth for maximizing the SNR in certain conditions.

  8. Investigation of the bandwidth of multimode optical fibers used with 1550-nm LED and laser sources

    NASA Technical Reports Server (NTRS)

    White, Preston A., III

    1992-01-01

    Multimode optical fibers are not intended to be used with 1550-nm sources; however, it is desirable to utilize 1300/1550-nm wavelength division multiplexing (WDM) on some multimode fibers at Kennedy Space Center (KSC). No information from fiber vendors nor from the literature is available to support this use. Preliminary studies at KSC have suggested that these fibers might be usable at 1550-nm if the fibers possessed enough bandwidth when sourced by LEDs. Detailed bandwidth studies were made on 12 multimode fibers using 1300- and 1550-nm lasers and LEDs. The results showed that the modal bandwidth at 1550-nm was about 50 percent of the 1300-nm value and that the chromatic dispersion could be predicted by extrapolating the vendor's specifications for wavelengths outside the 1550-nm region. Utilizing these data, predictions of the fiber's optical bandwidth were accurately made. Problems with launch conditions and possible differential attenuation at connectors was noted at 1300-nm but was less significant at 1550-nm. It appears that the multimode fibers studied will offer adequate performance in the 1550-nm region for a number of current KSC needs. Studies of additional fibers are encouraged to gain more confidence and better understanding of the 1550-nm bandwidth of KSC's multimode optical fibers before committing to 1300/1550-nm WDM.

  9. Optimizing Bandwidth Limited Problems Using One-SidedCommunication and Overlap

    SciTech Connect

    Bell, Christian; Bonachea, Dan; Nishtala, Rajesh; Yelick, Katherine

    2005-10-14

    Partitioned Global Address Space languages like Unified Parallel C (UPC) are typically valued for their expressiveness, especially for computations with fine-grained random accesses. In this paper we show that the one-sided communication model used in these languages also has a significant performance advantage for bandwidth-limited applications. We demonstrate this benefit through communication microbenchmarks and a case-study that compares UPC and MPI implementations of the NAS Fourier Transform (FT) benchmark. Our optimizations rely on aggressively overlapping communication with computation but spreading communication events throughout the course of the local computation. This alleviates the potential communication bottleneck that occurs when the communication is packed into a single phase (e.g., the large all-to-all in a multidimensional FFT). Even though the new algorithms require more messages for the same total volume of data, the resulting overlap leads to speedups of over 1.75x and 1.9x for the two-sided and one-sided implementations, respectively, when compared to the default NAS Fortran/MPI release. Our best one-sided implementations show an average improvement of 15 percent over our best two-sided implementations. We attribute this difference to the lower software overhead of one-sided communication, which is partly fundamental to the semantic difference between one-sided and two-sided communication. Our UPC results use the Berkeley UPC compiler with the GASNet communication system, and demonstrate the portability and scalability of that language and implementation, with performance approaching 0.5TFlop/s on the FT benchmark running on 512 processors.

  10. DPAL pump system exceeding 3kW at 766nm and 30 GHz bandwidth

    NASA Astrophysics Data System (ADS)

    Koenning, Tobias; McCormick, Dan; Irwin, David; Stapleton, Dean; Guiney, Tina; Patterson, Steve

    2016-03-01

    Due to their low quantum defect, diode pumped alkali metal vapor lasers (DPALs) offer the promise of scalability to very high average power levels while maintaining excellent beam quality. Research on DPALs has progressed to ever increasing power levels across multiple gain media species over the last years, necessitating pump power in the kW range. Each material requires a specific pump wavelength: near 852nm for cesium, 780nm for rubidium, 766nm for potassium, and 670nm for lithium atoms. The shorter pump wavelength below 800nm are outside the typical wavelength range for pump diodes developed for diode pumped solid state lasers (DPSS). The biggest challenge in pumping these materials efficiently is the need for maintaining the narrow gain media absorption band of approximately 0.01nm while greatly increasing power. Typical high power diode lasers achieve spectral widths around 3nm (FWHM) in the near infrared spectrum, but optical gratings may be used internal or external to the cavity to reduce the spectral width. Recently, experimental results have shown yet narrower line widths ranging from picometers at very low power levels to sub-100 picometers for water cooled stacks around 1kW of output power. The focus of this work is the development of a fiber-based pump system for potassium DPAL. The individual tasks are the development of high power 766nm chip material, a fiber-coupled module as a building block, and a scalable system design to address power requirements from hundreds of watts to tens of kilowatts. Results for a 3kW system achieving ~30GHz bandwidth at 766nm will be shown. Approaches for power-scaling and size reduction will be discussed.

  11. Technologies for low-bandwidth high-latency unmanned ground vehicle control

    NASA Astrophysics Data System (ADS)

    Pace, Teresa; Cogan, Ken; Hunt, Lee; Restine, Paul

    2014-05-01

    Automation technology has evolved at a rapid pace in recent years; however, many real-world problems require contextual understanding, problem solving, and other forms of higher-order thinking that extends beyond the capabilities of robots for the foreseeable future. This limits the complexity of automation which can be supplied to modern unmanned ground robots (UGV) and necessitates human-in-the-loop monitoring and control for some portions of missions. In order for the human operator to make decisions and provide tasking during key portions of the mission, existing solutions first derive significant information from a potentially dense reconstruction of the scene utilizing LIDAR, video, and other onboard sensors. A dense reconstruction contains too much data for real-time transmission over a modern wireless data link, so the robot electronics must first condense the scene representation prior to transmission. The control station receives this condensed scene representations and provides visual information to the human operator; the human operator then provides tele-operation commands in real-time to the robot. This paper discusses approaches to dense scene reduction of the data required to transmit to a human-in-the loop as well as the challenges associated with them. In addition, the complex and unstructured nature of real-world environments increases the need for tele-operation. Furthermore, many environments reduce the bandwidth and increase the latency of the link. Ultimately, worsening conditions will cause the tele-operation control process to break down, rendering the robot ineffective. In a worst-case scenario, extreme conditions causing a complete loss-of-communications could result in mission failure and loss of the vehicle.

  12. Detection algorithm of big bandwidth chirp signals based on STFT

    NASA Astrophysics Data System (ADS)

    Wang, Jinzhen; Wu, Juhong; Su, Shaoying; Chen, Zengping

    2014-10-01

    Aiming at solving the problem of detecting the wideband chirp signals under low Signal-to-Noise Ratio (SNR) condition, an effective signal detection algorithm based on Short-Time-Fourier-Transform (STFT) is proposed. Considering the characteristic of dispersion of noise spectrum and concentration of chirp spectrum, STFT is performed on chirp signals with Gauss window by fixed step, and these frequencies of peak spectrum obtained from every STFT are in correspondence to the time of every stepped window. Then, the frequencies are binarized and the approach similar to mnk method in time domain is used to detect the chirp pulse signal and determine the coarse starting time and ending time. Finally, the data segments, where the former starting time and ending time locate, are subdivided into many segments evenly, on which the STFT is implemented respectively. By that, the precise starting and ending time are attained. Simulations shows that when the SNR is higher than -28dB, the detection probability is not less than 99% and false alarm probability is zero, and also good estimation accuracy of starting and ending time is acquired. The algorithm is easy to realize and surpasses FFT in computation when the width of STFT window and step length are selected properly, so the presented algorithm has good engineering value.

  13. Bandwidth reduction of high-frequency sonar imagery in shallow water using content-adaptive hybrid image coding

    NASA Astrophysics Data System (ADS)

    Shin, Frances B.; Kil, David H.

    1998-09-01

    One of the biggest challenges in distributed underwater mine warfare for area sanitization and safe power projection during regional conflicts is transmission of compressed raw imagery data to a central processing station via a limited bandwidth channel while preserving crucial target information for further detection and automatic target recognition processing. Moreover, operating in an extremely shallow water with fluctuating channels and numerous interfering sources makes it imperative that image compression algorithms effectively deal with background nonstationarity within an image as well as content variation between images. In this paper, we present a novel approach to lossy image compression that combines image- content classification, content-adaptive bit allocation, and hybrid wavelet tree-based coding for over 100:1 bandwidth reduction with little sacrifice in signal-to-noise ratio (SNR). Our algorithm comprises (1) content-adaptive coding that takes advantage of a classify-before-coding strategy to reduce data mismatch, (2) subimage transformation for energy compaction, and (3) a wavelet tree-based coding for efficient encoding of significant wavelet coefficients. Furthermore, instead of using the embedded zerotree coding with scalar quantization (SQ), we investigate the use of a hybrid coding strategy that combines SQ for high-magnitude outlier transform coefficients and classified vector quantization (CVQ) for compactly clustered coefficients. This approach helps us achieve reduced distortion error and robustness while achieving high compression ratio. Our analysis based on the high-frequency sonar real data that exhibit severe content variability and contain both mines and mine-like clutter indicates that we can achieve over 100:1 compression ratio without losing crucial signal attributes. In comparison, benchmarking of the same data set with the best still-picture compression algorithm called the set partitioning in hierarchical trees (SPIHT) reveals

  14. Local intelligent electronic device (IED) rendering templates over limited bandwidth communication link to manage remote IED

    DOEpatents

    Bradetich, Ryan; Dearien, Jason A; Grussling, Barry Jakob; Remaley, Gavin

    2013-11-05

    The present disclosure provides systems and methods for remote device management. According to various embodiments, a local intelligent electronic device (IED) may be in communication with a remote IED via a limited bandwidth communication link, such as a serial link. The limited bandwidth communication link may not support traditional remote management interfaces. According to one embodiment, a local IED may present an operator with a management interface for a remote IED by rendering locally stored templates. The local IED may render the locally stored templates using sparse data obtained from the remote IED. According to various embodiments, the management interface may be a web client interface and/or an HTML interface. The bandwidth required to present a remote management interface may be significantly reduced by rendering locally stored templates rather than requesting an entire management interface from the remote IED. According to various embodiments, an IED may comprise an encryption transceiver.

  15. Circularly polarised printed antenna with wide axial-ratio bandwidth using strip dipoles and slots

    NASA Astrophysics Data System (ADS)

    Ito, K.

    1983-10-01

    A circularly polarised series-fed printed-array antenna having a wide axial-ratio bandwidth (for an axial ratio of less than 3 dB) is realised by combining strip dipoles with slots. To form a free-space dipole, i.e. a complementary radiator to a slot, the strip dipole is constructed by modifying the strip radiator of a circularly polarised antenna. Several experiments verify that the strip dipole behaves like a free-space dipole. A design procedure of the circularly polarised printed antenna with a wide axial-ratio bandwidth is described. On the basis of the design procedure, two types of the array antenna having different strip-dipole spacings are made and measured at S-band. An axial-ratio bandwidth of about 27 percent is obtained for the three sets of the radiators, although the actual gain is less than 0 dBi because the impedance matching is neglected.

  16. Investigating the influence of chromatic aberration and optical illumination bandwidth on fundus imaging in rats

    NASA Astrophysics Data System (ADS)

    Li, Hao; Liu, Wenzhong; Zhang, Hao F.

    2015-10-01

    Rodent models are indispensable in studying various retinal diseases. Noninvasive, high-resolution retinal imaging of rodent models is highly desired for longitudinally investigating the pathogenesis and therapeutic strategies. However, due to severe aberrations, the retinal image quality in rodents can be much worse than that in humans. We numerically and experimentally investigated the influence of chromatic aberration and optical illumination bandwidth on retinal imaging. We confirmed that the rat retinal image quality decreased with increasing illumination bandwidth. We achieved the retinal image resolution of 10 μm using a 19 nm illumination bandwidth centered at 580 nm in a home-built fundus camera. Furthermore, we observed higher chromatic aberration in albino rat eyes than in pigmented rat eyes. This study provides a design guide for high-resolution fundus camera for rodents. Our method is also beneficial to dispersion compensation in multiwavelength retinal imaging applications.

  17. A reflected-wave ruby maser with K-band tuning range and large instantaneous bandwidth

    NASA Technical Reports Server (NTRS)

    Moore, C. R.; Clauss, R. C.

    1979-01-01

    A novel maser concept is outlined and a unique design described which permits wide bandwidth and waveguide tuning range by employing four stages cascaded via cryogenically cooled circulators. Theoretical considerations for gain, bandwidth, gain ripple, and noise temperature are included. Operated on a closed-cycle helium refrigerator with a superconducting persistence-mode magnet, the four-stage amplifier is tunable from 18.3 to 26.6 GHz with 30 dB of net gain and achieves 240 MHz of 3-dB bandwidth near the center of this band. The measured noise temperature is 13 + or - 2 K referred to the room-temperature input flange. Applications are foreseen utilizing cooled parametric downconverters and upconverters with this amplifier at IF to extend the low-noise performance up to millimeter frequencies and down to L-band for radio astronomy and planetary spacecraft communications.

  18. Analysis of Blocking Rate and Bandwidth Usage of Mobile IPTV Services in Wireless Cellular Networks

    PubMed Central

    Li, Mingfu

    2014-01-01

    Mobile IPTV services over wireless cellular networks become more and more popular, owing to the significant growth in access bandwidth of wireless cellular networks such as 3G/4G and WiMAX. However, the spectrum resources of wireless cellular networks is rare. How to enhance the spectral efficiency of mobile networks becomes an important issue. Unicast, broadcast, and multicast are the most important transport schemes for offering mobile IPTV services over wireless cellular networks. Therefore, bandwidth usages and blocking rates of unicast, broadcast, and multicast IPTV services were analyzed and compared in this paper. Simulations were also conducted to validate the analytical results. Numerical results demonstrate that the presented analysis is correct, and multicast scheme achieves the best bandwidth usage and blocking rate performance, relative to the other two schemes. PMID:25379521

  19. Broadband parametric amplification with impedance engineering: Beyond the gain-bandwidth product

    NASA Astrophysics Data System (ADS)

    Roy, Tanay; Kundu, Suman; Chand, Madhavi; Vadiraj, A. M.; Ranadive, A.; Nehra, N.; Patankar, Meghan P.; Aumentado, J.; Clerk, A. A.; Vijay, R.

    2015-12-01

    We present an impedance engineered Josephson parametric amplifier capable of providing bandwidth beyond the traditional gain-bandwidth product. We achieve this by introducing a positive linear slope in the imaginary component of the input impedance seen by the Josephson oscillator using a λ / 2 transformer. Our theoretical model predicts an extremely flat gain profile with a bandwidth enhancement proportional to the square root of amplitude gain. We experimentally demonstrate a nearly flat 20 dB gain over a 640 MHz band, along with a mean 1-dB compression point of -110 dBm and near quantum-limited noise. The results are in a good agreement with our theoretical model.

  20. A high-bandwidth amplitude estimation technique for dynamic mode atomic force microscopy.

    PubMed

    Karvinen, K S; Moheimani, S O R

    2014-02-01

    While often overlooked, one of the prerequisites for high-speed amplitude modulation atomic force microscopy is a high-bandwidth amplitude estimation technique. Conventional techniques, such as RMS to DC conversion and the lock-in amplifier, have proven useful, but offer limited measurement bandwidth and are not suitable for high-speed imaging. Several groups have developed techniques, but many of these are either difficult to implement or lack robustness. In this contribution, we briefly outline existing amplitude estimation methods and propose a new high-bandwidth estimation technique, inspired by techniques employed in microwave and RF circuit design, which utilizes phase cancellation to significantly improve the performance of the lock-in amplifier. We conclude with the design and implementation of a custom circuit to experimentally demonstrate the improvements and discuss its application in high-speed and multifrequency atomic force microscopy. PMID:24593371

  1. A high-bandwidth amplitude estimation technique for dynamic mode atomic force microscopy

    SciTech Connect

    Karvinen, K. S. Moheimani, S. O. R.

    2014-02-15

    While often overlooked, one of the prerequisites for high-speed amplitude modulation atomic force microscopy is a high-bandwidth amplitude estimation technique. Conventional techniques, such as RMS to DC conversion and the lock-in amplifier, have proven useful, but offer limited measurement bandwidth and are not suitable for high-speed imaging. Several groups have developed techniques, but many of these are either difficult to implement or lack robustness. In this contribution, we briefly outline existing amplitude estimation methods and propose a new high-bandwidth estimation technique, inspired by techniques employed in microwave and RF circuit design, which utilizes phase cancellation to significantly improve the performance of the lock-in amplifier. We conclude with the design and implementation of a custom circuit to experimentally demonstrate the improvements and discuss its application in high-speed and multifrequency atomic force microscopy.

  2. Silicon waveguide infrared photodiodes with >35 GHz bandwidth and phototransistors with 50 AW-1 response.

    PubMed

    Geis, M W; Spector, S J; Grein, M E; Yoon, J U; Lennon, D M; Lyszczarz, T M

    2009-03-30

    SOI CMOS compatible Si waveguide photodetectors are made responsive from 1100 to 1750 nm by Si+ implantation and annealing. Photodiodes have a bandwidth of >35 GHz, an internal quantum efficiency of 0.5 to 10 AW-1, and leakage currents of 0.5 nA to 0.5 microA. Phototransistors have an optical response of 50 AW-1 with a bandwidth of 0.2 GHz. These properties are related to carrier mobilities in the implanted Si waveguide. These detectors exhibit low optical absorption requiring lengths from <0.3 mm to 3 mm to absorb 50% of the incoming light. However, the high bandwidth, high quantum efficiency, low leakage current, and potentially high fabrication yields, make these devices very competitive when compared to other detector technologies. PMID:19333283

  3. An optimized bandwidth efficient demand assigned protocol for integrated Mobile Satellite Services

    NASA Technical Reports Server (NTRS)

    Yan, T.-Y.; Wang, C. C.

    1985-01-01

    This paper describes the design of a demand assigned protocol based on bandwidth efficiency for integrated services of a Mobile Satellite System (MSS). An MSS provides data (closed-ended) and voice (open-ended) communications services for a large number of mobile users dispersed over a wide geographical area. Each mobile requests its desired service through a designated set of channels to a network management center. Either pure or slotted ALOHA random access scheme can be used to make connection requests, while data and voice communications are demand assigned. All channels have equal bandwidth and can be adaptively used for reservation requests, data connections or voice connections to maximize the bandwidth utilization. In this paper, perfect communications channels are assumed. It has been shown that, for the case considered, using the slotted ALOHA scheme for making connection requests can save about 30 percent on the total number of channels over using the pure ALHOA scheme.

  4. Global path and bandwidth scheduling in inter-data-center IP/optical transport network

    NASA Astrophysics Data System (ADS)

    Zhao, Yang; Wang, Lei; Chen, Xue; Yang, Futao; Shi, Sheping; Wang, Huitao

    2016-07-01

    We propose a flow-oriented global path and bandwidth scheduling scheme for inter-data-center IP/optical network. To improve the throughput of network and reduce the mutual impact between flows, we allow each flow to be carried by a multi-path optical channel data unit (ODU) channel. In addition bandwidth is allocated to flows fairly according to weight. Simulation results reveal that compared to high-priority-first mechanism, the method proposed improves average bandwidth allocation ratio by about 15% and allocation fairness between flows by 30%. Furthermore, compared to pure IP network, router ports are significantly saved and network cost can be reduced by up to 40% with scheme proposed in unified controlled IP/optical network.

  5. Optimizing the bandwidth and noise performance of distributed multi-pump Raman amplifiers

    NASA Astrophysics Data System (ADS)

    Liu, Xueming; Li, Yanhe

    2004-02-01

    Based on hybrid genetic algorithm (HGA), the signal bandwidth of the distributed multi-pump Raman amplifiers is optimized, and the corresponding noise figure is obtained. The results show that: (1) the optimal signal bandwidth Δ λ decreases with the increase of the span length L, e.g., Δ λ is 79.6 nm for L=50 km and 41.5 nm for L=100 km under our simulated conditions; (2) the relationship between Δ λ and L is approximately linear; (3) the equivalent noise figure can be negative and increases with the extension of L; (4) there are one or several global maximum signal bandwidth on the determinate conditions; (5) to realize the fixed Δ λ, several candidates can be obtained by means of HGA, as has important applications on the design of distributed multi-pump Raman amplifiers in practice.

  6. Analysis of blocking rate and bandwidth usage of mobile IPTV services in wireless cellular networks.

    PubMed

    Li, Mingfu

    2014-01-01

    Mobile IPTV services over wireless cellular networks become more and more popular, owing to the significant growth in access bandwidth of wireless cellular networks such as 3G/4G and WiMAX. However, the spectrum resources of wireless cellular networks is rare. How to enhance the spectral efficiency of mobile networks becomes an important issue. Unicast, broadcast, and multicast are the most important transport schemes for offering mobile IPTV services over wireless cellular networks. Therefore, bandwidth usages and blocking rates of unicast, broadcast, and multicast IPTV services were analyzed and compared in this paper. Simulations were also conducted to validate the analytical results. Numerical results demonstrate that the presented analysis is correct, and multicast scheme achieves the best bandwidth usage and blocking rate performance, relative to the other two schemes. PMID:25379521

  7. Efficient time-slot assignment algorithms for SS/TDMA systems with variable-bandwidth beams

    NASA Astrophysics Data System (ADS)

    Chalasani, Suresh; Varma, Anujan

    1994-02-01

    In this paper, we present efficient sequential and parallel algorithms for computation of time-slot assignments in SS/TDMA (satellite-switched /time-division multiple-access) systems with variable-bandwidth beams. These algorithms are based on modeling the time-slot assignment (TSA) problem as a network-flow problem. Our sequential algorithm, in general, has a better time-complexity than a previous algorithm due to Gopal, et al. and generates fewer switching matrices. If M (N) is the number of uplink (downlink) beams, L is the length of any optimal TSA, and alpha is the maximum bandwidth of an uplink or downlink beam, our sequential algorithm takes O ((M x N)(exp 3)) min(MN alpha, L) time to compute an optimal TSA when the traffic-handling capacity of the satellite is of the same order as the total bandwidth of the links.

  8. Investigating the influence of chromatic aberration and optical illumination bandwidth on fundus imaging in rats.

    PubMed

    Li, Hao; Liu, Wenzhong; Zhang, Hao F

    2015-10-01

    Abstract. Rodent models are indispensable in studying various retinal diseases. Noninvasive, high-resolution retinal imaging of rodent models is highly desired for longitudinally investigating the pathogenesis and therapeutic strategies. However, due to severe aberrations, the retinal image quality in rodents can be much worse than that in humans. We numerically and experimentally investigated the influence of chromatic aberration and optical illumination bandwidth on retinal imaging. We confirmed that the rat retinal image quality decreased with increasing illumination bandwidth. We achieved the retinal image resolution of 10  μm using a 19 nm illumination bandwidth centered at 580 nm in a home-built fundus camera. Furthermore, we observed higher chromatic aberration in albino rat eyes than in pigmented rat eyes. This study provides a design guide for high-resolution fundus camera for rodents. Our method is also beneficial to dispersion compensation in multiwavelength retinal imaging applications. PMID:26502233

  9. Angular phase-matching bandwidths in biaxial nonlinear crystals for frequency converters

    SciTech Connect

    Grechin, Sergei G

    2010-11-13

    It is shown that the angular phase-matching bandwidths in biaxial nonlinear crystals in the general case must be calculated in the coordinate system in which the angular deviations of the crystal and the laser beam divergence are determined consistently. The angular phase-matching bandwidths in this coordinate system may considerably differ from the conventionally determined values. The optimum orientation of the coordinate system for determining the angular phase-matching bandwidths is found. It is established that, in the general case in biaxial crystals, as in uniaxial ones, phase matching is always angle-critical along one coordinate and noncritical along the other and that it is possible to realise angle-noncritical phase matching of the fourth order. (nonlinear optical phenomena)

  10. Influence of finite bandwidth on the propagation of information in fast- and slow-light media

    NASA Astrophysics Data System (ADS)

    Amano, Heisuke; Tomita, Makoto

    2016-06-01

    We examined the propagation of information encoded as nonanalytical points on temporally Gaussian-shaped optical pulses in fast- and slow-light systems. The bandwidth of the input pulses determined the sharpness of the nonanalytical points. A sharp bending nonanalytical point propagated with luminal velocity in both fast- and slow-light systems, in good agreement with relativistic causality. As the bandwidth was reduced, the bending point became broad and propagated with the relevant group velocities. This transition was, however, qualitatively different in the fast- and slow-light systems. We also examined the predictability of the future pulse shape beyond the practical nonanalytical point on the basis of the expansion. When the bandwidth was reduced below a critical value, the expansion well predicted the future pulse shape.

  11. Frequency up-converted wide bandwidth piezoelectric energy harvester using mechanical impact

    NASA Astrophysics Data System (ADS)

    Halim, Miah A.; Khym, S.; Park, J. Y.

    2013-07-01

    This paper presents an impact based frequency up-converted wide bandwidth piezoelectric energy harvester in which two high frequency piezoelectric generating beams are struck at the same time by a low frequency driving beam having horizontally extended tip mass. Change of driving beam's effective stiffness during coupled vibration after impact allows the device to broaden the -3dB bandwidth to approximately 170% and to acquire more than 61% of the maximum power generation in the vicinity (from 7 to 10.5 Hz) of the -3 dB bandwidth region as well. The efficiency of electrical power transfer is increased to approximately 85%. Each generating beam produces 377 μW peak power at 14.5 Hz under 0.6 g acceleration with corresponding power density 58.8 μW cm-3.

  12. Acceptability of reactors in space

    SciTech Connect

    Buden, D.

    1981-04-01

    Reactors are the key to our future expansion into space. However, there has been some confusion in the public as to whether they are a safe and acceptable technology for use in space. The answer to these questions is explored. The US position is that when reactors are the preferred technical choice, that they can be used safely. In fact, it dies not appear that reactors add measurably to the risk associated with the Space Transportation System.

  13. Acceptability of reactors in space

    SciTech Connect

    Buden, D.

    1981-01-01

    Reactors are the key to our future expansion into space. However, there has been some confusion in the public as to whether they are a safe and acceptable technology for use in space. The answer to these questions is explored. The US position is that when reactors are the preferred technical choice, that they can be used safely. In fact, it does not appear that reactors add measurably to the risk associated with the Space Transportation System.

  14. Reactor tank UT acceptance criteria

    SciTech Connect

    Daugherty, W.L.

    1990-01-30

    The SRS reactor tanks are constructed of type 304 stainless steel, with 0.5 inch thick walls. An ultrasonic (UT) in-service inspection program has been developed for examination of these tanks, in accordance with the ISI Plan for the Savannah River Production Reactors Process Water System (DPSTM-88-100-1). Prior to initiation of these inspections, criteria for the disposition of any indications that might be found are required. A working group has been formed to review available information on the SRS reactor tanks and develop acceptance criteria. This working group includes nationally recognized experts in the nuclear industry. The working group has met three times and produced three documents describing the proposed acceptance criteria, the technical basis for the criteria and a proposed initial sampling plan. This report transmits these three documents, which were prepared in accordance with the technical task plan and quality assurance plan for this task, task 88-001-A- 1. In addition, this report summarizes the acceptance criteria and proposed sampling plan, and provides further interpretation of the intent of these three documents where necessary.

  15. Improving the chaos bandwidth of a semiconductor laser with phase-conjugate feedback

    NASA Astrophysics Data System (ADS)

    Mercier, Émeric; Wolfersberger, Delphine; Sciamanna, Marc

    2016-04-01

    Common applications using optical chaos in a semiconductor laser include, among others, random number generation and chaos-encrypted communications. They rely on chaos of high dimension with a large bandwidth and a high entropy growth rate to achieve good results. Optical chaos from a semiconductor laser with conventional optical feedback (COF) is typically used as the primary source of chaos. Additional enhancing techniques are used to enlarge the chaos bandwidth. In this contribution, we show experimentally how using phase-conjugate feedback (PCF) can naturally produce a chaos of higher bandwidth than COF. PCF is an alternative to COF which consists of feeding the conjugate of the optical output back into the laser cavity, with a time-delay. Thanks to an oscilloscope with a fast sampling rate, and a large bandwidth, we were able to measure and observe the time-resolved frequency dynamics with a good precision. In the regime of low-frequency fluctuations (LFF), where dropouts of optical power occur randomly, we were able to compare the difference in dynamics before and after a dropout, for PCF and COF. In the range of attainable reflectivities, we measured a bandwidth increase of up to 27 % with PCF when compared to COF. Interestingly, we found that high-frequency dynamics are enabled before dropouts in PCF, where it was theoretically shown that the system jumps between destabilized self-pulsing states at harmonics of the external-cavity frequency, the so-called external-cavity modes (ECMs). This observation tends to confirm that ECMs in PCF are indeed fundamentally different than ECMs in COF, where they are simple steady-states. Finally, we believe that the enhancing techniques used with COF could also be used with PCF to obtain even wider chaotic bandwidths. These results could lead to studies about the dimension and the entropy growth rate of chaos from a laser diode with PCF.

  16. Power and Efficiency Optimized in Traveling-Wave Tubes Over a Broad Frequency Bandwidth

    NASA Technical Reports Server (NTRS)

    Wilson, Jeffrey D.

    2001-01-01

    A traveling-wave tube (TWT) is an electron beam device that is used to amplify electromagnetic communication waves at radio and microwave frequencies. TWT's are critical components in deep space probes, communication satellites, and high-power radar systems. Power conversion efficiency is of paramount importance for TWT's employed in deep space probes and communication satellites. A previous effort was very successful in increasing efficiency and power at a single frequency (ref. 1). Such an algorithm is sufficient for narrow bandwidth designs, but for optimal designs in applications that require high radiofrequency power over a wide bandwidth, such as high-density communications or high-resolution radar, the variation of the circuit response with respect to frequency must be considered. This work at the NASA Glenn Research Center is the first to develop techniques for optimizing TWT efficiency and output power over a broad frequency bandwidth (ref. 2). The techniques are based on simulated annealing, which has the advantage over conventional optimization techniques in that it enables the best possible solution to be obtained (ref. 3). Two new broadband simulated annealing algorithms were developed that optimize (1) minimum saturated power efficiency over a frequency bandwidth and (2) simultaneous bandwidth and minimum power efficiency over the frequency band with constant input power. The algorithms were incorporated into the NASA coupled-cavity TWT computer model (ref. 4) and used to design optimal phase velocity tapers using the 59- to 64-GHz Hughes 961HA coupled-cavity TWT as a baseline model. In comparison to the baseline design, the computational results of the first broad-band design algorithm show an improvement of 73.9 percent in minimum saturated efficiency (see the top graph). The second broadband design algorithm (see the bottom graph) improves minimum radiofrequency efficiency with constant input power drive by a factor of 2.7 at the high band edge (64

  17. Apparatus and method for increasing the bandwidth of a laser beam

    DOEpatents

    Chaffee, Paul H.

    1991-01-01

    A method and apparatus is disclosed that provides a laser output beam having a broad bandwidth and an intensity smooth over time. The bandwidth of the laser output can be varied easily by varying the intensity of a broadband source. The present invention includes an optical modulation apparatus comprising a narrowband laser that outputs a horizontally polarized beam (a "signal beam") and a broadband laser that outputs a vertically polarized beam (a "pump beam") whose intensity varies rapidly. The two beam are coupled into a birefringent laser material so that the respective polarizations coincide with the principal axes of the material. As the two beams travel through the material, the polarization preserving properties of the birefringent material maintain the respective polarizations of the two beam; however there is coupling between the two beams as a result of cross phase modulations, which induces a bandwidth change of the signal beam. The amount of bandwidth change is dependent upon the average intensity of the pump beam. The beams are coupled out from the birefringent material and the modulated signal beam is separated by a polarization selector. The modulated signal beam now has a wider bandwidth, and its shape remains smooth in time. This signal beam can be applied to incoherence inducing systems. The different bandwidths required by these different incoherence inducing systems can be obtained by varying the intensity of the pump beam. The United States Government has rights in this invention pursuant to Contract No. W7405-ENG-48 between the United States Department of Energy and the University of California for the operation of Lawrence Livermore National Laboratory.

  18. ECG feature extraction based on the bandwidth properties of variational mode decomposition.

    PubMed

    Mert, Ahmet

    2016-04-01

    It is a difficult process to detect abnormal heart beats, known as arrhythmia, in long-term ECG recording. Thus, computer-aided diagnosis systems have become a supportive tool for helping physicians improve the diagnostic accuracy of heartbeat detection. This paper explores the bandwidth properties of the modes obtained using variational mode decomposition (VMD) to classify arrhythmia electrocardiogram (ECG) beats. VMD is an enhanced version of the empirical mode decomposition (EMD) algorithm for analyzing non-linear and non-stationary signals. It decomposes the signal into a set of band-limited oscillations called modes. ECG signals from the MIT-BIH arrhythmia database are decomposed using VMD, and the amplitude modulation bandwidth B AM, the frequency modulation bandwidth B FM and the total bandwidth B of the modes are used as feature vectors to detect heartbeats such as normal (N), premature ventricular contraction (V), left bundle branch block (L), right bundle branch block (R), paced beat (P) and atrial premature beat (A). Bandwidth estimations based on the instantaneous frequency (IF) and amplitude (IA) spectra of the modes indicate that the proposed VMD-based features have sufficient class discrimination capability regarding ECG beats. Moreover, the extracted features using the bandwidths (B AM, B FM and B) of four modes are used to evaluate the diagnostic accuracy rates of several classifiers such as the k-nearest neighbor classifier (k-NN), the decision tree (DT), the artificial neural network (ANN), the bagged decision tree (BDT), the AdaBoost decision tree (ABDT) and random sub-spaced k-NN (RSNN) for N, R, L, V, P, and A beats. The performance of the proposed VMD-based feature extraction with a BDT classifier has accuracy rates of 99.06%, 99.00%, 99.40%, 99.51%, 98.72%, 98.71%, and 99.02% for overall, N-, R-, L-, V-, P-, and A-type ECG beats, respectively. PMID:26987295

  19. 12 CFR 7.1007 - Acceptances.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 1 2010-01-01 2010-01-01 false Acceptances. 7.1007 Section 7.1007 Banks and... § 7.1007 Acceptances. A national bank is not limited in the character of acceptances it may make in financing credit transactions. Bankers' acceptances may be used for such purpose, since the making...

  20. 12 CFR 7.1007 - Acceptances.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 1 2011-01-01 2011-01-01 false Acceptances. 7.1007 Section 7.1007 Banks and... § 7.1007 Acceptances. A national bank is not limited in the character of acceptances it may make in financing credit transactions. Bankers' acceptances may be used for such purpose, since the making...